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131 | .IX Title ""<STANDARD INPUT>" 1" |
126 | .IX Title "LIBEV 3" |
132 | .TH "<STANDARD INPUT>" 1 "2007-11-29" "perl v5.8.8" "User Contributed Perl Documentation" |
127 | .TH LIBEV 3 "2009-07-15" "libev-3.7" "libev - high performance full featured event loop" |
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130 | .if n .ad l |
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131 | .nh |
133 | .SH "NAME" |
132 | .SH "NAME" |
134 | libev \- a high performance full\-featured event loop written in C |
133 | libev \- a high performance full\-featured event loop written in C |
135 | .SH "SYNOPSIS" |
134 | .SH "SYNOPSIS" |
136 | .IX Header "SYNOPSIS" |
135 | .IX Header "SYNOPSIS" |
137 | .Vb 1 |
136 | .Vb 1 |
138 | \& #include <ev.h> |
137 | \& #include <ev.h> |
139 | .Ve |
138 | .Ve |
140 | .SH "EXAMPLE PROGRAM" |
139 | .SS "\s-1EXAMPLE\s0 \s-1PROGRAM\s0" |
141 | .IX Header "EXAMPLE PROGRAM" |
140 | .IX Subsection "EXAMPLE PROGRAM" |
142 | .Vb 1 |
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143 | \& #include <ev.h> |
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144 | .Ve |
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145 | .PP |
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146 | .Vb 2 |
141 | .Vb 2 |
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142 | \& // a single header file is required |
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143 | \& #include <ev.h> |
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144 | \& |
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145 | \& #include <stdio.h> // for puts |
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146 | \& |
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147 | \& // every watcher type has its own typedef\*(Aqd struct |
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148 | \& // with the name ev_TYPE |
147 | \& ev_io stdin_watcher; |
149 | \& ev_io stdin_watcher; |
148 | \& ev_timer timeout_watcher; |
150 | \& ev_timer timeout_watcher; |
149 | .Ve |
151 | \& |
150 | .PP |
152 | \& // all watcher callbacks have a similar signature |
151 | .Vb 8 |
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152 | \& /* called when data readable on stdin */ |
153 | \& // this callback is called when data is readable on stdin |
153 | \& static void |
154 | \& static void |
154 | \& stdin_cb (EV_P_ struct ev_io *w, int revents) |
155 | \& stdin_cb (EV_P_ ev_io *w, int revents) |
155 | \& { |
156 | \& { |
156 | \& /* puts ("stdin ready"); */ |
157 | \& puts ("stdin ready"); |
157 | \& ev_io_stop (EV_A_ w); /* just a syntax example */ |
158 | \& // for one\-shot events, one must manually stop the watcher |
158 | \& ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */ |
159 | \& // with its corresponding stop function. |
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160 | \& ev_io_stop (EV_A_ w); |
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161 | \& |
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162 | \& // this causes all nested ev_loop\*(Aqs to stop iterating |
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163 | \& ev_unloop (EV_A_ EVUNLOOP_ALL); |
159 | \& } |
164 | \& } |
160 | .Ve |
165 | \& |
161 | .PP |
166 | \& // another callback, this time for a time\-out |
162 | .Vb 6 |
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163 | \& static void |
167 | \& static void |
164 | \& timeout_cb (EV_P_ struct ev_timer *w, int revents) |
168 | \& timeout_cb (EV_P_ ev_timer *w, int revents) |
165 | \& { |
169 | \& { |
166 | \& /* puts ("timeout"); */ |
170 | \& puts ("timeout"); |
167 | \& ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */ |
171 | \& // this causes the innermost ev_loop to stop iterating |
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172 | \& ev_unloop (EV_A_ EVUNLOOP_ONE); |
168 | \& } |
173 | \& } |
169 | .Ve |
174 | \& |
170 | .PP |
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171 | .Vb 4 |
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172 | \& int |
175 | \& int |
173 | \& main (void) |
176 | \& main (void) |
174 | \& { |
177 | \& { |
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178 | \& // use the default event loop unless you have special needs |
175 | \& struct ev_loop *loop = ev_default_loop (0); |
179 | \& struct ev_loop *loop = ev_default_loop (0); |
176 | .Ve |
180 | \& |
177 | .PP |
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178 | .Vb 3 |
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179 | \& /* initialise an io watcher, then start it */ |
181 | \& // initialise an io watcher, then start it |
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182 | \& // this one will watch for stdin to become readable |
180 | \& ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
183 | \& ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
181 | \& ev_io_start (loop, &stdin_watcher); |
184 | \& ev_io_start (loop, &stdin_watcher); |
182 | .Ve |
185 | \& |
183 | .PP |
186 | \& // initialise a timer watcher, then start it |
184 | .Vb 3 |
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185 | \& /* simple non-repeating 5.5 second timeout */ |
187 | \& // simple non\-repeating 5.5 second timeout |
186 | \& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
188 | \& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
187 | \& ev_timer_start (loop, &timeout_watcher); |
189 | \& ev_timer_start (loop, &timeout_watcher); |
188 | .Ve |
190 | \& |
189 | .PP |
191 | \& // now wait for events to arrive |
190 | .Vb 2 |
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191 | \& /* loop till timeout or data ready */ |
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192 | \& ev_loop (loop, 0); |
192 | \& ev_loop (loop, 0); |
193 | .Ve |
193 | \& |
194 | .PP |
194 | \& // unloop was called, so exit |
195 | .Vb 2 |
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196 | \& return 0; |
195 | \& return 0; |
197 | \& } |
196 | \& } |
198 | .Ve |
197 | .Ve |
199 | .SH "DESCRIPTION" |
198 | .SH "ABOUT THIS DOCUMENT" |
200 | .IX Header "DESCRIPTION" |
199 | .IX Header "ABOUT THIS DOCUMENT" |
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200 | This document documents the libev software package. |
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201 | .PP |
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202 | The newest version of this document is also available as an html-formatted |
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203 | web page you might find easier to navigate when reading it for the first |
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204 | time: <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>. |
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205 | .PP |
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206 | While this document tries to be as complete as possible in documenting |
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207 | libev, its usage and the rationale behind its design, it is not a tutorial |
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208 | on event-based programming, nor will it introduce event-based programming |
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209 | with libev. |
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210 | .PP |
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211 | Familarity with event based programming techniques in general is assumed |
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212 | throughout this document. |
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213 | .SH "ABOUT LIBEV" |
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214 | .IX Header "ABOUT LIBEV" |
201 | Libev is an event loop: you register interest in certain events (such as a |
215 | Libev is an event loop: you register interest in certain events (such as a |
202 | file descriptor being readable or a timeout occuring), and it will manage |
216 | file descriptor being readable or a timeout occurring), and it will manage |
203 | these event sources and provide your program with events. |
217 | these event sources and provide your program with events. |
204 | .PP |
218 | .PP |
205 | To do this, it must take more or less complete control over your process |
219 | To do this, it must take more or less complete control over your process |
206 | (or thread) by executing the \fIevent loop\fR handler, and will then |
220 | (or thread) by executing the \fIevent loop\fR handler, and will then |
207 | communicate events via a callback mechanism. |
221 | communicate events via a callback mechanism. |
208 | .PP |
222 | .PP |
209 | You register interest in certain events by registering so-called \fIevent |
223 | You register interest in certain events by registering so-called \fIevent |
210 | watchers\fR, which are relatively small C structures you initialise with the |
224 | watchers\fR, which are relatively small C structures you initialise with the |
211 | details of the event, and then hand it over to libev by \fIstarting\fR the |
225 | details of the event, and then hand it over to libev by \fIstarting\fR the |
212 | watcher. |
226 | watcher. |
213 | .SH "FEATURES" |
227 | .SS "\s-1FEATURES\s0" |
214 | .IX Header "FEATURES" |
228 | .IX Subsection "FEATURES" |
215 | Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the Linux-specific \f(CW\*(C`epoll\*(C'\fR, the |
229 | Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the Linux-specific \f(CW\*(C`epoll\*(C'\fR, the |
216 | BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port mechanisms |
230 | BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port mechanisms |
217 | for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR interface |
231 | for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR interface |
218 | (for \f(CW\*(C`ev_stat\*(C'\fR), relative timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers |
232 | (for \f(CW\*(C`ev_stat\*(C'\fR), relative timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers |
219 | with customised rescheduling (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals |
233 | with customised rescheduling (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals |
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222 | \&\f(CW\*(C`ev_embed\*(C'\fR, \f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR watchers) as well as |
236 | \&\f(CW\*(C`ev_embed\*(C'\fR, \f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR watchers) as well as |
223 | file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even limited support for fork events |
237 | file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even limited support for fork events |
224 | (\f(CW\*(C`ev_fork\*(C'\fR). |
238 | (\f(CW\*(C`ev_fork\*(C'\fR). |
225 | .PP |
239 | .PP |
226 | It also is quite fast (see this |
240 | It also is quite fast (see this |
227 | benchmark comparing it to libevent |
241 | <benchmark> comparing it to libevent |
228 | for example). |
242 | for example). |
229 | .SH "CONVENTIONS" |
243 | .SS "\s-1CONVENTIONS\s0" |
230 | .IX Header "CONVENTIONS" |
244 | .IX Subsection "CONVENTIONS" |
231 | Libev is very configurable. In this manual the default configuration will |
245 | Libev is very configurable. In this manual the default (and most common) |
232 | be described, which supports multiple event loops. For more info about |
246 | configuration will be described, which supports multiple event loops. For |
233 | various configuration options please have a look at \fB\s-1EMBED\s0\fR section in |
247 | more info about various configuration options please have a look at |
234 | this manual. If libev was configured without support for multiple event |
248 | \&\fB\s-1EMBED\s0\fR section in this manual. If libev was configured without support |
235 | loops, then all functions taking an initial argument of name \f(CW\*(C`loop\*(C'\fR |
249 | for multiple event loops, then all functions taking an initial argument of |
236 | (which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) will not have this argument. |
250 | name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`ev_loop *\*(C'\fR) will not have |
237 | .SH "TIME REPRESENTATION" |
251 | this argument. |
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252 | .SS "\s-1TIME\s0 \s-1REPRESENTATION\s0" |
238 | .IX Header "TIME REPRESENTATION" |
253 | .IX Subsection "TIME REPRESENTATION" |
239 | Libev represents time as a single floating point number, representing the |
254 | Libev represents time as a single floating point number, representing |
240 | (fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere near |
255 | the (fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere |
241 | the beginning of 1970, details are complicated, don't ask). This type is |
256 | near the beginning of 1970, details are complicated, don't ask). This |
242 | called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually aliases |
257 | type is called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually |
243 | to the \f(CW\*(C`double\*(C'\fR type in C, and when you need to do any calculations on |
258 | aliases to the \f(CW\*(C`double\*(C'\fR type in C. When you need to do any calculations |
244 | it, you should treat it as such. |
259 | on it, you should treat it as some floating point value. Unlike the name |
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260 | component \f(CW\*(C`stamp\*(C'\fR might indicate, it is also used for time differences |
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261 | throughout libev. |
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262 | .SH "ERROR HANDLING" |
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263 | .IX Header "ERROR HANDLING" |
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264 | Libev knows three classes of errors: operating system errors, usage errors |
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265 | and internal errors (bugs). |
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266 | .PP |
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267 | When libev catches an operating system error it cannot handle (for example |
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268 | a system call indicating a condition libev cannot fix), it calls the callback |
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269 | set via \f(CW\*(C`ev_set_syserr_cb\*(C'\fR, which is supposed to fix the problem or |
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270 | abort. The default is to print a diagnostic message and to call \f(CW\*(C`abort |
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271 | ()\*(C'\fR. |
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272 | .PP |
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273 | When libev detects a usage error such as a negative timer interval, then |
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274 | it will print a diagnostic message and abort (via the \f(CW\*(C`assert\*(C'\fR mechanism, |
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275 | so \f(CW\*(C`NDEBUG\*(C'\fR will disable this checking): these are programming errors in |
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276 | the libev caller and need to be fixed there. |
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277 | .PP |
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278 | Libev also has a few internal error-checking \f(CW\*(C`assert\*(C'\fRions, and also has |
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279 | extensive consistency checking code. These do not trigger under normal |
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280 | circumstances, as they indicate either a bug in libev or worse. |
245 | .SH "GLOBAL FUNCTIONS" |
281 | .SH "GLOBAL FUNCTIONS" |
246 | .IX Header "GLOBAL FUNCTIONS" |
282 | .IX Header "GLOBAL FUNCTIONS" |
247 | These functions can be called anytime, even before initialising the |
283 | These functions can be called anytime, even before initialising the |
248 | library in any way. |
284 | library in any way. |
249 | .IP "ev_tstamp ev_time ()" 4 |
285 | .IP "ev_tstamp ev_time ()" 4 |
250 | .IX Item "ev_tstamp ev_time ()" |
286 | .IX Item "ev_tstamp ev_time ()" |
251 | Returns the current time as libev would use it. Please note that the |
287 | Returns the current time as libev would use it. Please note that the |
252 | \&\f(CW\*(C`ev_now\*(C'\fR function is usually faster and also often returns the timestamp |
288 | \&\f(CW\*(C`ev_now\*(C'\fR function is usually faster and also often returns the timestamp |
253 | you actually want to know. |
289 | you actually want to know. |
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290 | .IP "ev_sleep (ev_tstamp interval)" 4 |
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291 | .IX Item "ev_sleep (ev_tstamp interval)" |
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292 | Sleep for the given interval: The current thread will be blocked until |
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293 | either it is interrupted or the given time interval has passed. Basically |
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294 | this is a sub-second-resolution \f(CW\*(C`sleep ()\*(C'\fR. |
254 | .IP "int ev_version_major ()" 4 |
295 | .IP "int ev_version_major ()" 4 |
255 | .IX Item "int ev_version_major ()" |
296 | .IX Item "int ev_version_major ()" |
256 | .PD 0 |
297 | .PD 0 |
257 | .IP "int ev_version_minor ()" 4 |
298 | .IP "int ev_version_minor ()" 4 |
258 | .IX Item "int ev_version_minor ()" |
299 | .IX Item "int ev_version_minor ()" |
259 | .PD |
300 | .PD |
260 | You can find out the major and minor version numbers of the library |
301 | You can find out the major and minor \s-1ABI\s0 version numbers of the library |
261 | you linked against by calling the functions \f(CW\*(C`ev_version_major\*(C'\fR and |
302 | you linked against by calling the functions \f(CW\*(C`ev_version_major\*(C'\fR and |
262 | \&\f(CW\*(C`ev_version_minor\*(C'\fR. If you want, you can compare against the global |
303 | \&\f(CW\*(C`ev_version_minor\*(C'\fR. If you want, you can compare against the global |
263 | symbols \f(CW\*(C`EV_VERSION_MAJOR\*(C'\fR and \f(CW\*(C`EV_VERSION_MINOR\*(C'\fR, which specify the |
304 | symbols \f(CW\*(C`EV_VERSION_MAJOR\*(C'\fR and \f(CW\*(C`EV_VERSION_MINOR\*(C'\fR, which specify the |
264 | version of the library your program was compiled against. |
305 | version of the library your program was compiled against. |
265 | .Sp |
306 | .Sp |
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307 | These version numbers refer to the \s-1ABI\s0 version of the library, not the |
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308 | release version. |
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309 | .Sp |
266 | Usually, it's a good idea to terminate if the major versions mismatch, |
310 | Usually, it's a good idea to terminate if the major versions mismatch, |
267 | as this indicates an incompatible change. Minor versions are usually |
311 | as this indicates an incompatible change. Minor versions are usually |
268 | compatible to older versions, so a larger minor version alone is usually |
312 | compatible to older versions, so a larger minor version alone is usually |
269 | not a problem. |
313 | not a problem. |
270 | .Sp |
314 | .Sp |
271 | Example: Make sure we haven't accidentally been linked against the wrong |
315 | Example: Make sure we haven't accidentally been linked against the wrong |
272 | version. |
316 | version. |
273 | .Sp |
317 | .Sp |
274 | .Vb 3 |
318 | .Vb 3 |
275 | \& assert (("libev version mismatch", |
319 | \& assert (("libev version mismatch", |
276 | \& ev_version_major () == EV_VERSION_MAJOR |
320 | \& ev_version_major () == EV_VERSION_MAJOR |
277 | \& && ev_version_minor () >= EV_VERSION_MINOR)); |
321 | \& && ev_version_minor () >= EV_VERSION_MINOR)); |
278 | .Ve |
322 | .Ve |
279 | .IP "unsigned int ev_supported_backends ()" 4 |
323 | .IP "unsigned int ev_supported_backends ()" 4 |
280 | .IX Item "unsigned int ev_supported_backends ()" |
324 | .IX Item "unsigned int ev_supported_backends ()" |
281 | Return the set of all backends (i.e. their corresponding \f(CW\*(C`EV_BACKEND_*\*(C'\fR |
325 | Return the set of all backends (i.e. their corresponding \f(CW\*(C`EV_BACKEND_*\*(C'\fR |
282 | value) compiled into this binary of libev (independent of their |
326 | value) compiled into this binary of libev (independent of their |
… | |
… | |
285 | .Sp |
329 | .Sp |
286 | Example: make sure we have the epoll method, because yeah this is cool and |
330 | Example: make sure we have the epoll method, because yeah this is cool and |
287 | a must have and can we have a torrent of it please!!!11 |
331 | a must have and can we have a torrent of it please!!!11 |
288 | .Sp |
332 | .Sp |
289 | .Vb 2 |
333 | .Vb 2 |
290 | \& assert (("sorry, no epoll, no sex", |
334 | \& assert (("sorry, no epoll, no sex", |
291 | \& ev_supported_backends () & EVBACKEND_EPOLL)); |
335 | \& ev_supported_backends () & EVBACKEND_EPOLL)); |
292 | .Ve |
336 | .Ve |
293 | .IP "unsigned int ev_recommended_backends ()" 4 |
337 | .IP "unsigned int ev_recommended_backends ()" 4 |
294 | .IX Item "unsigned int ev_recommended_backends ()" |
338 | .IX Item "unsigned int ev_recommended_backends ()" |
295 | Return the set of all backends compiled into this binary of libev and also |
339 | Return the set of all backends compiled into this binary of libev and also |
296 | recommended for this platform. This set is often smaller than the one |
340 | recommended for this platform. This set is often smaller than the one |
297 | returned by \f(CW\*(C`ev_supported_backends\*(C'\fR, as for example kqueue is broken on |
341 | returned by \f(CW\*(C`ev_supported_backends\*(C'\fR, as for example kqueue is broken on |
298 | most BSDs and will not be autodetected unless you explicitly request it |
342 | most BSDs and will not be auto-detected unless you explicitly request it |
299 | (assuming you know what you are doing). This is the set of backends that |
343 | (assuming you know what you are doing). This is the set of backends that |
300 | libev will probe for if you specify no backends explicitly. |
344 | libev will probe for if you specify no backends explicitly. |
301 | .IP "unsigned int ev_embeddable_backends ()" 4 |
345 | .IP "unsigned int ev_embeddable_backends ()" 4 |
302 | .IX Item "unsigned int ev_embeddable_backends ()" |
346 | .IX Item "unsigned int ev_embeddable_backends ()" |
303 | Returns the set of backends that are embeddable in other event loops. This |
347 | Returns the set of backends that are embeddable in other event loops. This |
304 | is the theoretical, all\-platform, value. To find which backends |
348 | is the theoretical, all-platform, value. To find which backends |
305 | might be supported on the current system, you would need to look at |
349 | might be supported on the current system, you would need to look at |
306 | \&\f(CW\*(C`ev_embeddable_backends () & ev_supported_backends ()\*(C'\fR, likewise for |
350 | \&\f(CW\*(C`ev_embeddable_backends () & ev_supported_backends ()\*(C'\fR, likewise for |
307 | recommended ones. |
351 | recommended ones. |
308 | .Sp |
352 | .Sp |
309 | See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
353 | See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
310 | .IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4 |
354 | .IP "ev_set_allocator (void *(*cb)(void *ptr, long size)) [\s-1NOT\s0 \s-1REENTRANT\s0]" 4 |
311 | .IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))" |
355 | .IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT]" |
312 | Sets the allocation function to use (the prototype is similar \- the |
356 | Sets the allocation function to use (the prototype is similar \- the |
313 | semantics is identical \- to the realloc C function). It is used to |
357 | semantics are identical to the \f(CW\*(C`realloc\*(C'\fR C89/SuS/POSIX function). It is |
314 | allocate and free memory (no surprises here). If it returns zero when |
358 | used to allocate and free memory (no surprises here). If it returns zero |
315 | memory needs to be allocated, the library might abort or take some |
359 | when memory needs to be allocated (\f(CW\*(C`size != 0\*(C'\fR), the library might abort |
316 | potentially destructive action. The default is your system realloc |
360 | or take some potentially destructive action. |
317 | function. |
361 | .Sp |
|
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362 | Since some systems (at least OpenBSD and Darwin) fail to implement |
|
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363 | correct \f(CW\*(C`realloc\*(C'\fR semantics, libev will use a wrapper around the system |
|
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364 | \&\f(CW\*(C`realloc\*(C'\fR and \f(CW\*(C`free\*(C'\fR functions by default. |
318 | .Sp |
365 | .Sp |
319 | You could override this function in high-availability programs to, say, |
366 | You could override this function in high-availability programs to, say, |
320 | free some memory if it cannot allocate memory, to use a special allocator, |
367 | free some memory if it cannot allocate memory, to use a special allocator, |
321 | or even to sleep a while and retry until some memory is available. |
368 | or even to sleep a while and retry until some memory is available. |
322 | .Sp |
369 | .Sp |
323 | Example: Replace the libev allocator with one that waits a bit and then |
370 | Example: Replace the libev allocator with one that waits a bit and then |
324 | retries). |
371 | retries (example requires a standards-compliant \f(CW\*(C`realloc\*(C'\fR). |
325 | .Sp |
372 | .Sp |
326 | .Vb 6 |
373 | .Vb 6 |
327 | \& static void * |
374 | \& static void * |
328 | \& persistent_realloc (void *ptr, size_t size) |
375 | \& persistent_realloc (void *ptr, size_t size) |
329 | \& { |
376 | \& { |
330 | \& for (;;) |
377 | \& for (;;) |
331 | \& { |
378 | \& { |
332 | \& void *newptr = realloc (ptr, size); |
379 | \& void *newptr = realloc (ptr, size); |
333 | .Ve |
380 | \& |
334 | .Sp |
|
|
335 | .Vb 2 |
|
|
336 | \& if (newptr) |
381 | \& if (newptr) |
337 | \& return newptr; |
382 | \& return newptr; |
338 | .Ve |
383 | \& |
339 | .Sp |
|
|
340 | .Vb 3 |
|
|
341 | \& sleep (60); |
384 | \& sleep (60); |
342 | \& } |
385 | \& } |
343 | \& } |
386 | \& } |
344 | .Ve |
387 | \& |
345 | .Sp |
|
|
346 | .Vb 2 |
|
|
347 | \& ... |
388 | \& ... |
348 | \& ev_set_allocator (persistent_realloc); |
389 | \& ev_set_allocator (persistent_realloc); |
349 | .Ve |
390 | .Ve |
350 | .IP "ev_set_syserr_cb (void (*cb)(const char *msg));" 4 |
391 | .IP "ev_set_syserr_cb (void (*cb)(const char *msg)); [\s-1NOT\s0 \s-1REENTRANT\s0]" 4 |
351 | .IX Item "ev_set_syserr_cb (void (*cb)(const char *msg));" |
392 | .IX Item "ev_set_syserr_cb (void (*cb)(const char *msg)); [NOT REENTRANT]" |
352 | Set the callback function to call on a retryable syscall error (such |
393 | Set the callback function to call on a retryable system call error (such |
353 | as failed select, poll, epoll_wait). The message is a printable string |
394 | as failed select, poll, epoll_wait). The message is a printable string |
354 | indicating the system call or subsystem causing the problem. If this |
395 | indicating the system call or subsystem causing the problem. If this |
355 | callback is set, then libev will expect it to remedy the sitution, no |
396 | callback is set, then libev will expect it to remedy the situation, no |
356 | matter what, when it returns. That is, libev will generally retry the |
397 | matter what, when it returns. That is, libev will generally retry the |
357 | requested operation, or, if the condition doesn't go away, do bad stuff |
398 | requested operation, or, if the condition doesn't go away, do bad stuff |
358 | (such as abort). |
399 | (such as abort). |
359 | .Sp |
400 | .Sp |
360 | Example: This is basically the same thing that libev does internally, too. |
401 | Example: This is basically the same thing that libev does internally, too. |
… | |
… | |
364 | \& fatal_error (const char *msg) |
405 | \& fatal_error (const char *msg) |
365 | \& { |
406 | \& { |
366 | \& perror (msg); |
407 | \& perror (msg); |
367 | \& abort (); |
408 | \& abort (); |
368 | \& } |
409 | \& } |
369 | .Ve |
410 | \& |
370 | .Sp |
|
|
371 | .Vb 2 |
|
|
372 | \& ... |
411 | \& ... |
373 | \& ev_set_syserr_cb (fatal_error); |
412 | \& ev_set_syserr_cb (fatal_error); |
374 | .Ve |
413 | .Ve |
375 | .SH "FUNCTIONS CONTROLLING THE EVENT LOOP" |
414 | .SH "FUNCTIONS CONTROLLING THE EVENT LOOP" |
376 | .IX Header "FUNCTIONS CONTROLLING THE EVENT LOOP" |
415 | .IX Header "FUNCTIONS CONTROLLING THE EVENT LOOP" |
377 | An event loop is described by a \f(CW\*(C`struct ev_loop *\*(C'\fR. The library knows two |
416 | An event loop is described by a \f(CW\*(C`struct ev_loop *\*(C'\fR (the \f(CW\*(C`struct\*(C'\fR |
378 | types of such loops, the \fIdefault\fR loop, which supports signals and child |
417 | is \fInot\fR optional in this case, as there is also an \f(CW\*(C`ev_loop\*(C'\fR |
379 | events, and dynamically created loops which do not. |
418 | \&\fIfunction\fR). |
380 | .PP |
419 | .PP |
381 | If you use threads, a common model is to run the default event loop |
420 | The library knows two types of such loops, the \fIdefault\fR loop, which |
382 | in your main thread (or in a separate thread) and for each thread you |
421 | supports signals and child events, and dynamically created loops which do |
383 | create, you also create another event loop. Libev itself does no locking |
422 | not. |
384 | whatsoever, so if you mix calls to the same event loop in different |
|
|
385 | threads, make sure you lock (this is usually a bad idea, though, even if |
|
|
386 | done correctly, because it's hideous and inefficient). |
|
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387 | .IP "struct ev_loop *ev_default_loop (unsigned int flags)" 4 |
423 | .IP "struct ev_loop *ev_default_loop (unsigned int flags)" 4 |
388 | .IX Item "struct ev_loop *ev_default_loop (unsigned int flags)" |
424 | .IX Item "struct ev_loop *ev_default_loop (unsigned int flags)" |
389 | This will initialise the default event loop if it hasn't been initialised |
425 | This will initialise the default event loop if it hasn't been initialised |
390 | yet and return it. If the default loop could not be initialised, returns |
426 | yet and return it. If the default loop could not be initialised, returns |
391 | false. If it already was initialised it simply returns it (and ignores the |
427 | false. If it already was initialised it simply returns it (and ignores the |
392 | flags. If that is troubling you, check \f(CW\*(C`ev_backend ()\*(C'\fR afterwards). |
428 | flags. If that is troubling you, check \f(CW\*(C`ev_backend ()\*(C'\fR afterwards). |
393 | .Sp |
429 | .Sp |
394 | If you don't know what event loop to use, use the one returned from this |
430 | If you don't know what event loop to use, use the one returned from this |
395 | function. |
431 | function. |
|
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432 | .Sp |
|
|
433 | Note that this function is \fInot\fR thread-safe, so if you want to use it |
|
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434 | from multiple threads, you have to lock (note also that this is unlikely, |
|
|
435 | as loops cannot be shared easily between threads anyway). |
|
|
436 | .Sp |
|
|
437 | The default loop is the only loop that can handle \f(CW\*(C`ev_signal\*(C'\fR and |
|
|
438 | \&\f(CW\*(C`ev_child\*(C'\fR watchers, and to do this, it always registers a handler |
|
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439 | for \f(CW\*(C`SIGCHLD\*(C'\fR. If this is a problem for your application you can either |
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440 | create a dynamic loop with \f(CW\*(C`ev_loop_new\*(C'\fR that doesn't do that, or you |
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441 | can simply overwrite the \f(CW\*(C`SIGCHLD\*(C'\fR signal handler \fIafter\fR calling |
|
|
442 | \&\f(CW\*(C`ev_default_init\*(C'\fR. |
396 | .Sp |
443 | .Sp |
397 | The flags argument can be used to specify special behaviour or specific |
444 | The flags argument can be used to specify special behaviour or specific |
398 | backends to use, and is usually specified as \f(CW0\fR (or \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). |
445 | backends to use, and is usually specified as \f(CW0\fR (or \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). |
399 | .Sp |
446 | .Sp |
400 | The following flags are supported: |
447 | The following flags are supported: |
… | |
… | |
405 | The default flags value. Use this if you have no clue (it's the right |
452 | The default flags value. Use this if you have no clue (it's the right |
406 | thing, believe me). |
453 | thing, believe me). |
407 | .ie n .IP """EVFLAG_NOENV""" 4 |
454 | .ie n .IP """EVFLAG_NOENV""" 4 |
408 | .el .IP "\f(CWEVFLAG_NOENV\fR" 4 |
455 | .el .IP "\f(CWEVFLAG_NOENV\fR" 4 |
409 | .IX Item "EVFLAG_NOENV" |
456 | .IX Item "EVFLAG_NOENV" |
410 | If this flag bit is ored into the flag value (or the program runs setuid |
457 | If this flag bit is or'ed into the flag value (or the program runs setuid |
411 | or setgid) then libev will \fInot\fR look at the environment variable |
458 | or setgid) then libev will \fInot\fR look at the environment variable |
412 | \&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will |
459 | \&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will |
413 | override the flags completely if it is found in the environment. This is |
460 | override the flags completely if it is found in the environment. This is |
414 | useful to try out specific backends to test their performance, or to work |
461 | useful to try out specific backends to test their performance, or to work |
415 | around bugs. |
462 | around bugs. |
… | |
… | |
420 | a fork, you can also make libev check for a fork in each iteration by |
467 | a fork, you can also make libev check for a fork in each iteration by |
421 | enabling this flag. |
468 | enabling this flag. |
422 | .Sp |
469 | .Sp |
423 | This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop, |
470 | This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop, |
424 | and thus this might slow down your event loop if you do a lot of loop |
471 | and thus this might slow down your event loop if you do a lot of loop |
425 | iterations and little real work, but is usually not noticable (on my |
472 | iterations and little real work, but is usually not noticeable (on my |
426 | Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence |
473 | GNU/Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence |
427 | without a syscall and thus \fIvery\fR fast, but my Linux system also has |
474 | without a system call and thus \fIvery\fR fast, but my GNU/Linux system also has |
428 | \&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster). |
475 | \&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster). |
429 | .Sp |
476 | .Sp |
430 | The big advantage of this flag is that you can forget about fork (and |
477 | The big advantage of this flag is that you can forget about fork (and |
431 | forget about forgetting to tell libev about forking) when you use this |
478 | forget about forgetting to tell libev about forking) when you use this |
432 | flag. |
479 | flag. |
433 | .Sp |
480 | .Sp |
434 | This flag setting cannot be overriden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR |
481 | This flag setting cannot be overridden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR |
435 | environment variable. |
482 | environment variable. |
436 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
483 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
437 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
484 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
438 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
485 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
439 | This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
486 | This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
440 | libev tries to roll its own fd_set with no limits on the number of fds, |
487 | libev tries to roll its own fd_set with no limits on the number of fds, |
441 | but if that fails, expect a fairly low limit on the number of fds when |
488 | but if that fails, expect a fairly low limit on the number of fds when |
442 | using this backend. It doesn't scale too well (O(highest_fd)), but its usually |
489 | using this backend. It doesn't scale too well (O(highest_fd)), but its |
443 | the fastest backend for a low number of fds. |
490 | usually the fastest backend for a low number of (low-numbered :) fds. |
|
|
491 | .Sp |
|
|
492 | To get good performance out of this backend you need a high amount of |
|
|
493 | parallelism (most of the file descriptors should be busy). If you are |
|
|
494 | writing a server, you should \f(CW\*(C`accept ()\*(C'\fR in a loop to accept as many |
|
|
495 | connections as possible during one iteration. You might also want to have |
|
|
496 | a look at \f(CW\*(C`ev_set_io_collect_interval ()\*(C'\fR to increase the amount of |
|
|
497 | readiness notifications you get per iteration. |
|
|
498 | .Sp |
|
|
499 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR to the \f(CW\*(C`readfds\*(C'\fR set and \f(CW\*(C`EV_WRITE\*(C'\fR to the |
|
|
500 | \&\f(CW\*(C`writefds\*(C'\fR set (and to work around Microsoft Windows bugs, also onto the |
|
|
501 | \&\f(CW\*(C`exceptfds\*(C'\fR set on that platform). |
444 | .ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4 |
502 | .ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4 |
445 | .el .IP "\f(CWEVBACKEND_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4 |
503 | .el .IP "\f(CWEVBACKEND_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4 |
446 | .IX Item "EVBACKEND_POLL (value 2, poll backend, available everywhere except on windows)" |
504 | .IX Item "EVBACKEND_POLL (value 2, poll backend, available everywhere except on windows)" |
447 | And this is your standard \fIpoll\fR\|(2) backend. It's more complicated than |
505 | And this is your standard \fIpoll\fR\|(2) backend. It's more complicated |
448 | select, but handles sparse fds better and has no artificial limit on the |
506 | than select, but handles sparse fds better and has no artificial |
449 | number of fds you can use (except it will slow down considerably with a |
507 | limit on the number of fds you can use (except it will slow down |
450 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds). |
508 | considerably with a lot of inactive fds). It scales similarly to select, |
|
|
509 | i.e. O(total_fds). See the entry for \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR, above, for |
|
|
510 | performance tips. |
|
|
511 | .Sp |
|
|
512 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR to \f(CW\*(C`POLLIN | POLLERR | POLLHUP\*(C'\fR, and |
|
|
513 | \&\f(CW\*(C`EV_WRITE\*(C'\fR to \f(CW\*(C`POLLOUT | POLLERR | POLLHUP\*(C'\fR. |
451 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
514 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
452 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
515 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
453 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
516 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
454 | For few fds, this backend is a bit little slower than poll and select, |
517 | For few fds, this backend is a bit little slower than poll and select, |
455 | but it scales phenomenally better. While poll and select usually scale like |
518 | but it scales phenomenally better. While poll and select usually scale |
456 | O(total_fds) where n is the total number of fds (or the highest fd), epoll scales |
519 | like O(total_fds) where n is the total number of fds (or the highest fd), |
457 | either O(1) or O(active_fds). |
520 | epoll scales either O(1) or O(active_fds). |
458 | .Sp |
521 | .Sp |
|
|
522 | The epoll mechanism deserves honorable mention as the most misdesigned |
|
|
523 | of the more advanced event mechanisms: mere annoyances include silently |
|
|
524 | dropping file descriptors, requiring a system call per change per file |
|
|
525 | descriptor (and unnecessary guessing of parameters), problems with dup and |
|
|
526 | so on. The biggest issue is fork races, however \- if a program forks then |
|
|
527 | \&\fIboth\fR parent and child process have to recreate the epoll set, which can |
|
|
528 | take considerable time (one syscall per file descriptor) and is of course |
|
|
529 | hard to detect. |
|
|
530 | .Sp |
|
|
531 | Epoll is also notoriously buggy \- embedding epoll fds \fIshould\fR work, but |
|
|
532 | of course \fIdoesn't\fR, and epoll just loves to report events for totally |
|
|
533 | \&\fIdifferent\fR file descriptors (even already closed ones, so one cannot |
|
|
534 | even remove them from the set) than registered in the set (especially |
|
|
535 | on \s-1SMP\s0 systems). Libev tries to counter these spurious notifications by |
|
|
536 | employing an additional generation counter and comparing that against the |
|
|
537 | events to filter out spurious ones, recreating the set when required. |
|
|
538 | .Sp |
459 | While stopping and starting an I/O watcher in the same iteration will |
539 | While stopping, setting and starting an I/O watcher in the same iteration |
460 | result in some caching, there is still a syscall per such incident |
540 | will result in some caching, there is still a system call per such |
461 | (because the fd could point to a different file description now), so its |
541 | incident (because the same \fIfile descriptor\fR could point to a different |
462 | best to avoid that. Also, \fIdup()\fRed file descriptors might not work very |
542 | \&\fIfile description\fR now), so its best to avoid that. Also, \f(CW\*(C`dup ()\*(C'\fR'ed |
463 | well if you register events for both fds. |
543 | file descriptors might not work very well if you register events for both |
|
|
544 | file descriptors. |
464 | .Sp |
545 | .Sp |
465 | Please note that epoll sometimes generates spurious notifications, so you |
546 | Best performance from this backend is achieved by not unregistering all |
466 | need to use non-blocking I/O or other means to avoid blocking when no data |
547 | watchers for a file descriptor until it has been closed, if possible, |
467 | (or space) is available. |
548 | i.e. keep at least one watcher active per fd at all times. Stopping and |
|
|
549 | starting a watcher (without re-setting it) also usually doesn't cause |
|
|
550 | extra overhead. A fork can both result in spurious notifications as well |
|
|
551 | as in libev having to destroy and recreate the epoll object, which can |
|
|
552 | take considerable time and thus should be avoided. |
|
|
553 | .Sp |
|
|
554 | All this means that, in practice, \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR can be as fast or |
|
|
555 | faster than epoll for maybe up to a hundred file descriptors, depending on |
|
|
556 | the usage. So sad. |
|
|
557 | .Sp |
|
|
558 | While nominally embeddable in other event loops, this feature is broken in |
|
|
559 | all kernel versions tested so far. |
|
|
560 | .Sp |
|
|
561 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
|
|
562 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
468 | .ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 |
563 | .ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 |
469 | .el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 |
564 | .el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 |
470 | .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" |
565 | .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" |
471 | Kqueue deserves special mention, as at the time of this writing, it |
566 | Kqueue deserves special mention, as at the time of this writing, it |
472 | was broken on all BSDs except NetBSD (usually it doesn't work with |
567 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
473 | anything but sockets and pipes, except on Darwin, where of course its |
568 | with anything but sockets and pipes, except on Darwin, where of course |
474 | completely useless). For this reason its not being \*(L"autodetected\*(R" |
569 | it's completely useless). Unlike epoll, however, whose brokenness |
|
|
570 | is by design, these kqueue bugs can (and eventually will) be fixed |
|
|
571 | without \s-1API\s0 changes to existing programs. For this reason it's not being |
475 | unless you explicitly specify it explicitly in the flags (i.e. using |
572 | \&\*(L"auto-detected\*(R" unless you explicitly specify it in the flags (i.e. using |
476 | \&\f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR). |
573 | \&\f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR) or libev was compiled on a known-to-be-good (\-enough) |
|
|
574 | system like NetBSD. |
|
|
575 | .Sp |
|
|
576 | You still can embed kqueue into a normal poll or select backend and use it |
|
|
577 | only for sockets (after having made sure that sockets work with kqueue on |
|
|
578 | the target platform). See \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
477 | .Sp |
579 | .Sp |
478 | It scales in the same way as the epoll backend, but the interface to the |
580 | It scales in the same way as the epoll backend, but the interface to the |
479 | kernel is more efficient (which says nothing about its actual speed, of |
581 | kernel is more efficient (which says nothing about its actual speed, of |
480 | course). While starting and stopping an I/O watcher does not cause an |
582 | course). While stopping, setting and starting an I/O watcher does never |
481 | extra syscall as with epoll, it still adds up to four event changes per |
583 | cause an extra system call as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to |
482 | incident, so its best to avoid that. |
584 | two event changes per incident. Support for \f(CW\*(C`fork ()\*(C'\fR is very bad (but |
|
|
585 | sane, unlike epoll) and it drops fds silently in similarly hard-to-detect |
|
|
586 | cases |
|
|
587 | .Sp |
|
|
588 | This backend usually performs well under most conditions. |
|
|
589 | .Sp |
|
|
590 | While nominally embeddable in other event loops, this doesn't work |
|
|
591 | everywhere, so you might need to test for this. And since it is broken |
|
|
592 | almost everywhere, you should only use it when you have a lot of sockets |
|
|
593 | (for which it usually works), by embedding it into another event loop |
|
|
594 | (e.g. \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR (but \f(CW\*(C`poll\*(C'\fR is of course |
|
|
595 | also broken on \s-1OS\s0 X)) and, did I mention it, using it only for sockets. |
|
|
596 | .Sp |
|
|
597 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR into an \f(CW\*(C`EVFILT_READ\*(C'\fR kevent with |
|
|
598 | \&\f(CW\*(C`NOTE_EOF\*(C'\fR, and \f(CW\*(C`EV_WRITE\*(C'\fR into an \f(CW\*(C`EVFILT_WRITE\*(C'\fR kevent with |
|
|
599 | \&\f(CW\*(C`NOTE_EOF\*(C'\fR. |
483 | .ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 |
600 | .ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 |
484 | .el .IP "\f(CWEVBACKEND_DEVPOLL\fR (value 16, Solaris 8)" 4 |
601 | .el .IP "\f(CWEVBACKEND_DEVPOLL\fR (value 16, Solaris 8)" 4 |
485 | .IX Item "EVBACKEND_DEVPOLL (value 16, Solaris 8)" |
602 | .IX Item "EVBACKEND_DEVPOLL (value 16, Solaris 8)" |
486 | This is not implemented yet (and might never be). |
603 | This is not implemented yet (and might never be, unless you send me an |
|
|
604 | implementation). According to reports, \f(CW\*(C`/dev/poll\*(C'\fR only supports sockets |
|
|
605 | and is not embeddable, which would limit the usefulness of this backend |
|
|
606 | immensely. |
487 | .ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 |
607 | .ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 |
488 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
608 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
489 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
609 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
490 | This uses the Solaris 10 port mechanism. As with everything on Solaris, |
610 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
491 | it's really slow, but it still scales very well (O(active_fds)). |
611 | it's really slow, but it still scales very well (O(active_fds)). |
492 | .Sp |
612 | .Sp |
493 | Please note that solaris ports can result in a lot of spurious |
613 | Please note that Solaris event ports can deliver a lot of spurious |
494 | notifications, so you need to use non-blocking I/O or other means to avoid |
614 | notifications, so you need to use non-blocking I/O or other means to avoid |
495 | blocking when no data (or space) is available. |
615 | blocking when no data (or space) is available. |
|
|
616 | .Sp |
|
|
617 | While this backend scales well, it requires one system call per active |
|
|
618 | file descriptor per loop iteration. For small and medium numbers of file |
|
|
619 | descriptors a \*(L"slow\*(R" \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR backend |
|
|
620 | might perform better. |
|
|
621 | .Sp |
|
|
622 | On the positive side, with the exception of the spurious readiness |
|
|
623 | notifications, this backend actually performed fully to specification |
|
|
624 | in all tests and is fully embeddable, which is a rare feat among the |
|
|
625 | OS-specific backends (I vastly prefer correctness over speed hacks). |
|
|
626 | .Sp |
|
|
627 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
|
|
628 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
496 | .ie n .IP """EVBACKEND_ALL""" 4 |
629 | .ie n .IP """EVBACKEND_ALL""" 4 |
497 | .el .IP "\f(CWEVBACKEND_ALL\fR" 4 |
630 | .el .IP "\f(CWEVBACKEND_ALL\fR" 4 |
498 | .IX Item "EVBACKEND_ALL" |
631 | .IX Item "EVBACKEND_ALL" |
499 | Try all backends (even potentially broken ones that wouldn't be tried |
632 | Try all backends (even potentially broken ones that wouldn't be tried |
500 | with \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). Since this is a mask, you can do stuff such as |
633 | with \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). Since this is a mask, you can do stuff such as |
501 | \&\f(CW\*(C`EVBACKEND_ALL & ~EVBACKEND_KQUEUE\*(C'\fR. |
634 | \&\f(CW\*(C`EVBACKEND_ALL & ~EVBACKEND_KQUEUE\*(C'\fR. |
|
|
635 | .Sp |
|
|
636 | It is definitely not recommended to use this flag. |
502 | .RE |
637 | .RE |
503 | .RS 4 |
638 | .RS 4 |
504 | .Sp |
639 | .Sp |
505 | If one or more of these are ored into the flags value, then only these |
640 | If one or more of these are or'ed into the flags value, then only these |
506 | backends will be tried (in the reverse order as given here). If none are |
641 | backends will be tried (in the reverse order as listed here). If none are |
507 | specified, most compiled-in backend will be tried, usually in reverse |
642 | specified, all backends in \f(CW\*(C`ev_recommended_backends ()\*(C'\fR will be tried. |
508 | order of their flag values :) |
|
|
509 | .Sp |
643 | .Sp |
510 | The most typical usage is like this: |
644 | Example: This is the most typical usage. |
511 | .Sp |
645 | .Sp |
512 | .Vb 2 |
646 | .Vb 2 |
513 | \& if (!ev_default_loop (0)) |
647 | \& if (!ev_default_loop (0)) |
514 | \& fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
648 | \& fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
515 | .Ve |
649 | .Ve |
516 | .Sp |
650 | .Sp |
517 | Restrict libev to the select and poll backends, and do not allow |
651 | Example: Restrict libev to the select and poll backends, and do not allow |
518 | environment settings to be taken into account: |
652 | environment settings to be taken into account: |
519 | .Sp |
653 | .Sp |
520 | .Vb 1 |
654 | .Vb 1 |
521 | \& ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
655 | \& ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
522 | .Ve |
656 | .Ve |
523 | .Sp |
657 | .Sp |
524 | Use whatever libev has to offer, but make sure that kqueue is used if |
658 | Example: Use whatever libev has to offer, but make sure that kqueue is |
525 | available (warning, breaks stuff, best use only with your own private |
659 | used if available (warning, breaks stuff, best use only with your own |
526 | event loop and only if you know the \s-1OS\s0 supports your types of fds): |
660 | private event loop and only if you know the \s-1OS\s0 supports your types of |
|
|
661 | fds): |
527 | .Sp |
662 | .Sp |
528 | .Vb 1 |
663 | .Vb 1 |
529 | \& ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
664 | \& ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
530 | .Ve |
665 | .Ve |
531 | .RE |
666 | .RE |
532 | .IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4 |
667 | .IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4 |
533 | .IX Item "struct ev_loop *ev_loop_new (unsigned int flags)" |
668 | .IX Item "struct ev_loop *ev_loop_new (unsigned int flags)" |
534 | Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is |
669 | Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is |
535 | always distinct from the default loop. Unlike the default loop, it cannot |
670 | always distinct from the default loop. Unlike the default loop, it cannot |
536 | handle signal and child watchers, and attempts to do so will be greeted by |
671 | handle signal and child watchers, and attempts to do so will be greeted by |
537 | undefined behaviour (or a failed assertion if assertions are enabled). |
672 | undefined behaviour (or a failed assertion if assertions are enabled). |
538 | .Sp |
673 | .Sp |
|
|
674 | Note that this function \fIis\fR thread-safe, and the recommended way to use |
|
|
675 | libev with threads is indeed to create one loop per thread, and using the |
|
|
676 | default loop in the \*(L"main\*(R" or \*(L"initial\*(R" thread. |
|
|
677 | .Sp |
539 | Example: Try to create a event loop that uses epoll and nothing else. |
678 | Example: Try to create a event loop that uses epoll and nothing else. |
540 | .Sp |
679 | .Sp |
541 | .Vb 3 |
680 | .Vb 3 |
542 | \& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
681 | \& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
543 | \& if (!epoller) |
682 | \& if (!epoller) |
544 | \& fatal ("no epoll found here, maybe it hides under your chair"); |
683 | \& fatal ("no epoll found here, maybe it hides under your chair"); |
545 | .Ve |
684 | .Ve |
546 | .IP "ev_default_destroy ()" 4 |
685 | .IP "ev_default_destroy ()" 4 |
547 | .IX Item "ev_default_destroy ()" |
686 | .IX Item "ev_default_destroy ()" |
548 | Destroys the default loop again (frees all memory and kernel state |
687 | Destroys the default loop again (frees all memory and kernel state |
549 | etc.). None of the active event watchers will be stopped in the normal |
688 | etc.). None of the active event watchers will be stopped in the normal |
550 | sense, so e.g. \f(CW\*(C`ev_is_active\*(C'\fR might still return true. It is your |
689 | sense, so e.g. \f(CW\*(C`ev_is_active\*(C'\fR might still return true. It is your |
551 | responsibility to either stop all watchers cleanly yoursef \fIbefore\fR |
690 | responsibility to either stop all watchers cleanly yourself \fIbefore\fR |
552 | calling this function, or cope with the fact afterwards (which is usually |
691 | calling this function, or cope with the fact afterwards (which is usually |
553 | the easiest thing, youc na just ignore the watchers and/or \f(CW\*(C`free ()\*(C'\fR them |
692 | the easiest thing, you can just ignore the watchers and/or \f(CW\*(C`free ()\*(C'\fR them |
554 | for example). |
693 | for example). |
|
|
694 | .Sp |
|
|
695 | Note that certain global state, such as signal state (and installed signal |
|
|
696 | handlers), will not be freed by this function, and related watchers (such |
|
|
697 | as signal and child watchers) would need to be stopped manually. |
|
|
698 | .Sp |
|
|
699 | In general it is not advisable to call this function except in the |
|
|
700 | rare occasion where you really need to free e.g. the signal handling |
|
|
701 | pipe fds. If you need dynamically allocated loops it is better to use |
|
|
702 | \&\f(CW\*(C`ev_loop_new\*(C'\fR and \f(CW\*(C`ev_loop_destroy\*(C'\fR). |
555 | .IP "ev_loop_destroy (loop)" 4 |
703 | .IP "ev_loop_destroy (loop)" 4 |
556 | .IX Item "ev_loop_destroy (loop)" |
704 | .IX Item "ev_loop_destroy (loop)" |
557 | Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an |
705 | Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an |
558 | earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR. |
706 | earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR. |
559 | .IP "ev_default_fork ()" 4 |
707 | .IP "ev_default_fork ()" 4 |
560 | .IX Item "ev_default_fork ()" |
708 | .IX Item "ev_default_fork ()" |
|
|
709 | This function sets a flag that causes subsequent \f(CW\*(C`ev_loop\*(C'\fR iterations |
561 | This function reinitialises the kernel state for backends that have |
710 | to reinitialise the kernel state for backends that have one. Despite the |
562 | one. Despite the name, you can call it anytime, but it makes most sense |
711 | name, you can call it anytime, but it makes most sense after forking, in |
563 | after forking, in either the parent or child process (or both, but that |
712 | the child process (or both child and parent, but that again makes little |
564 | again makes little sense). |
713 | sense). You \fImust\fR call it in the child before using any of the libev |
|
|
714 | functions, and it will only take effect at the next \f(CW\*(C`ev_loop\*(C'\fR iteration. |
565 | .Sp |
715 | .Sp |
566 | You \fImust\fR call this function in the child process after forking if and |
716 | On the other hand, you only need to call this function in the child |
567 | only if you want to use the event library in both processes. If you just |
717 | process if and only if you want to use the event library in the child. If |
568 | fork+exec, you don't have to call it. |
718 | you just fork+exec, you don't have to call it at all. |
569 | .Sp |
719 | .Sp |
570 | The function itself is quite fast and it's usually not a problem to call |
720 | The function itself is quite fast and it's usually not a problem to call |
571 | it just in case after a fork. To make this easy, the function will fit in |
721 | it just in case after a fork. To make this easy, the function will fit in |
572 | quite nicely into a call to \f(CW\*(C`pthread_atfork\*(C'\fR: |
722 | quite nicely into a call to \f(CW\*(C`pthread_atfork\*(C'\fR: |
573 | .Sp |
723 | .Sp |
574 | .Vb 1 |
724 | .Vb 1 |
575 | \& pthread_atfork (0, 0, ev_default_fork); |
725 | \& pthread_atfork (0, 0, ev_default_fork); |
576 | .Ve |
726 | .Ve |
577 | .Sp |
|
|
578 | At the moment, \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and \f(CW\*(C`EVBACKEND_POLL\*(C'\fR are safe to use |
|
|
579 | without calling this function, so if you force one of those backends you |
|
|
580 | do not need to care. |
|
|
581 | .IP "ev_loop_fork (loop)" 4 |
727 | .IP "ev_loop_fork (loop)" 4 |
582 | .IX Item "ev_loop_fork (loop)" |
728 | .IX Item "ev_loop_fork (loop)" |
583 | Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by |
729 | Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by |
584 | \&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop |
730 | \&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop |
585 | after fork, and how you do this is entirely your own problem. |
731 | after fork that you want to re-use in the child, and how you do this is |
|
|
732 | entirely your own problem. |
|
|
733 | .IP "int ev_is_default_loop (loop)" 4 |
|
|
734 | .IX Item "int ev_is_default_loop (loop)" |
|
|
735 | Returns true when the given loop is, in fact, the default loop, and false |
|
|
736 | otherwise. |
|
|
737 | .IP "unsigned int ev_loop_count (loop)" 4 |
|
|
738 | .IX Item "unsigned int ev_loop_count (loop)" |
|
|
739 | Returns the count of loop iterations for the loop, which is identical to |
|
|
740 | the number of times libev did poll for new events. It starts at \f(CW0\fR and |
|
|
741 | happily wraps around with enough iterations. |
|
|
742 | .Sp |
|
|
743 | This value can sometimes be useful as a generation counter of sorts (it |
|
|
744 | \&\*(L"ticks\*(R" the number of loop iterations), as it roughly corresponds with |
|
|
745 | \&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls. |
|
|
746 | .IP "unsigned int ev_loop_depth (loop)" 4 |
|
|
747 | .IX Item "unsigned int ev_loop_depth (loop)" |
|
|
748 | Returns the number of times \f(CW\*(C`ev_loop\*(C'\fR was entered minus the number of |
|
|
749 | times \f(CW\*(C`ev_loop\*(C'\fR was exited, in other words, the recursion depth. |
|
|
750 | .Sp |
|
|
751 | Outside \f(CW\*(C`ev_loop\*(C'\fR, this number is zero. In a callback, this number is |
|
|
752 | \&\f(CW1\fR, unless \f(CW\*(C`ev_loop\*(C'\fR was invoked recursively (or from another thread), |
|
|
753 | in which case it is higher. |
|
|
754 | .Sp |
|
|
755 | Leaving \f(CW\*(C`ev_loop\*(C'\fR abnormally (setjmp/longjmp, cancelling the thread |
|
|
756 | etc.), doesn't count as exit. |
586 | .IP "unsigned int ev_backend (loop)" 4 |
757 | .IP "unsigned int ev_backend (loop)" 4 |
587 | .IX Item "unsigned int ev_backend (loop)" |
758 | .IX Item "unsigned int ev_backend (loop)" |
588 | Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in |
759 | Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in |
589 | use. |
760 | use. |
590 | .IP "ev_tstamp ev_now (loop)" 4 |
761 | .IP "ev_tstamp ev_now (loop)" 4 |
591 | .IX Item "ev_tstamp ev_now (loop)" |
762 | .IX Item "ev_tstamp ev_now (loop)" |
592 | Returns the current \*(L"event loop time\*(R", which is the time the event loop |
763 | Returns the current \*(L"event loop time\*(R", which is the time the event loop |
593 | received events and started processing them. This timestamp does not |
764 | received events and started processing them. This timestamp does not |
594 | change as long as callbacks are being processed, and this is also the base |
765 | change as long as callbacks are being processed, and this is also the base |
595 | time used for relative timers. You can treat it as the timestamp of the |
766 | time used for relative timers. You can treat it as the timestamp of the |
596 | event occuring (or more correctly, libev finding out about it). |
767 | event occurring (or more correctly, libev finding out about it). |
|
|
768 | .IP "ev_now_update (loop)" 4 |
|
|
769 | .IX Item "ev_now_update (loop)" |
|
|
770 | Establishes the current time by querying the kernel, updating the time |
|
|
771 | returned by \f(CW\*(C`ev_now ()\*(C'\fR in the progress. This is a costly operation and |
|
|
772 | is usually done automatically within \f(CW\*(C`ev_loop ()\*(C'\fR. |
|
|
773 | .Sp |
|
|
774 | This function is rarely useful, but when some event callback runs for a |
|
|
775 | very long time without entering the event loop, updating libev's idea of |
|
|
776 | the current time is a good idea. |
|
|
777 | .Sp |
|
|
778 | See also \*(L"The special problem of time updates\*(R" in the \f(CW\*(C`ev_timer\*(C'\fR section. |
|
|
779 | .IP "ev_suspend (loop)" 4 |
|
|
780 | .IX Item "ev_suspend (loop)" |
|
|
781 | .PD 0 |
|
|
782 | .IP "ev_resume (loop)" 4 |
|
|
783 | .IX Item "ev_resume (loop)" |
|
|
784 | .PD |
|
|
785 | These two functions suspend and resume a loop, for use when the loop is |
|
|
786 | not used for a while and timeouts should not be processed. |
|
|
787 | .Sp |
|
|
788 | A typical use case would be an interactive program such as a game: When |
|
|
789 | the user presses \f(CW\*(C`^Z\*(C'\fR to suspend the game and resumes it an hour later it |
|
|
790 | would be best to handle timeouts as if no time had actually passed while |
|
|
791 | the program was suspended. This can be achieved by calling \f(CW\*(C`ev_suspend\*(C'\fR |
|
|
792 | in your \f(CW\*(C`SIGTSTP\*(C'\fR handler, sending yourself a \f(CW\*(C`SIGSTOP\*(C'\fR and calling |
|
|
793 | \&\f(CW\*(C`ev_resume\*(C'\fR directly afterwards to resume timer processing. |
|
|
794 | .Sp |
|
|
795 | Effectively, all \f(CW\*(C`ev_timer\*(C'\fR watchers will be delayed by the time spend |
|
|
796 | between \f(CW\*(C`ev_suspend\*(C'\fR and \f(CW\*(C`ev_resume\*(C'\fR, and all \f(CW\*(C`ev_periodic\*(C'\fR watchers |
|
|
797 | will be rescheduled (that is, they will lose any events that would have |
|
|
798 | occured while suspended). |
|
|
799 | .Sp |
|
|
800 | After calling \f(CW\*(C`ev_suspend\*(C'\fR you \fBmust not\fR call \fIany\fR function on the |
|
|
801 | given loop other than \f(CW\*(C`ev_resume\*(C'\fR, and you \fBmust not\fR call \f(CW\*(C`ev_resume\*(C'\fR |
|
|
802 | without a previous call to \f(CW\*(C`ev_suspend\*(C'\fR. |
|
|
803 | .Sp |
|
|
804 | Calling \f(CW\*(C`ev_suspend\*(C'\fR/\f(CW\*(C`ev_resume\*(C'\fR has the side effect of updating the |
|
|
805 | event loop time (see \f(CW\*(C`ev_now_update\*(C'\fR). |
597 | .IP "ev_loop (loop, int flags)" 4 |
806 | .IP "ev_loop (loop, int flags)" 4 |
598 | .IX Item "ev_loop (loop, int flags)" |
807 | .IX Item "ev_loop (loop, int flags)" |
599 | Finally, this is it, the event handler. This function usually is called |
808 | Finally, this is it, the event handler. This function usually is called |
600 | after you initialised all your watchers and you want to start handling |
809 | after you initialised all your watchers and you want to start handling |
601 | events. |
810 | events. |
… | |
… | |
603 | If the flags argument is specified as \f(CW0\fR, it will not return until |
812 | If the flags argument is specified as \f(CW0\fR, it will not return until |
604 | either no event watchers are active anymore or \f(CW\*(C`ev_unloop\*(C'\fR was called. |
813 | either no event watchers are active anymore or \f(CW\*(C`ev_unloop\*(C'\fR was called. |
605 | .Sp |
814 | .Sp |
606 | Please note that an explicit \f(CW\*(C`ev_unloop\*(C'\fR is usually better than |
815 | Please note that an explicit \f(CW\*(C`ev_unloop\*(C'\fR is usually better than |
607 | relying on all watchers to be stopped when deciding when a program has |
816 | relying on all watchers to be stopped when deciding when a program has |
608 | finished (especially in interactive programs), but having a program that |
817 | finished (especially in interactive programs), but having a program |
609 | automatically loops as long as it has to and no longer by virtue of |
818 | that automatically loops as long as it has to and no longer by virtue |
610 | relying on its watchers stopping correctly is a thing of beauty. |
819 | of relying on its watchers stopping correctly, that is truly a thing of |
|
|
820 | beauty. |
611 | .Sp |
821 | .Sp |
612 | A flags value of \f(CW\*(C`EVLOOP_NONBLOCK\*(C'\fR will look for new events, will handle |
822 | A flags value of \f(CW\*(C`EVLOOP_NONBLOCK\*(C'\fR will look for new events, will handle |
613 | those events and any outstanding ones, but will not block your process in |
823 | those events and any already outstanding ones, but will not block your |
614 | case there are no events and will return after one iteration of the loop. |
824 | process in case there are no events and will return after one iteration of |
|
|
825 | the loop. |
615 | .Sp |
826 | .Sp |
616 | A flags value of \f(CW\*(C`EVLOOP_ONESHOT\*(C'\fR will look for new events (waiting if |
827 | A flags value of \f(CW\*(C`EVLOOP_ONESHOT\*(C'\fR will look for new events (waiting if |
617 | neccessary) and will handle those and any outstanding ones. It will block |
828 | necessary) and will handle those and any already outstanding ones. It |
618 | your process until at least one new event arrives, and will return after |
829 | will block your process until at least one new event arrives (which could |
619 | one iteration of the loop. This is useful if you are waiting for some |
830 | be an event internal to libev itself, so there is no guarantee that a |
620 | external event in conjunction with something not expressible using other |
831 | user-registered callback will be called), and will return after one |
|
|
832 | iteration of the loop. |
|
|
833 | .Sp |
|
|
834 | This is useful if you are waiting for some external event in conjunction |
|
|
835 | with something not expressible using other libev watchers (i.e. "roll your |
621 | libev watchers. However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is |
836 | own \f(CW\*(C`ev_loop\*(C'\fR"). However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is |
622 | usually a better approach for this kind of thing. |
837 | usually a better approach for this kind of thing. |
623 | .Sp |
838 | .Sp |
624 | Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does: |
839 | Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does: |
625 | .Sp |
840 | .Sp |
626 | .Vb 18 |
841 | .Vb 10 |
627 | \& * If there are no active watchers (reference count is zero), return. |
842 | \& \- Before the first iteration, call any pending watchers. |
628 | \& - Queue prepare watchers and then call all outstanding watchers. |
843 | \& * If EVFLAG_FORKCHECK was used, check for a fork. |
|
|
844 | \& \- If a fork was detected (by any means), queue and call all fork watchers. |
|
|
845 | \& \- Queue and call all prepare watchers. |
629 | \& - If we have been forked, recreate the kernel state. |
846 | \& \- If we have been forked, detach and recreate the kernel state |
|
|
847 | \& as to not disturb the other process. |
630 | \& - Update the kernel state with all outstanding changes. |
848 | \& \- Update the kernel state with all outstanding changes. |
631 | \& - Update the "event loop time". |
849 | \& \- Update the "event loop time" (ev_now ()). |
632 | \& - Calculate for how long to block. |
850 | \& \- Calculate for how long to sleep or block, if at all |
|
|
851 | \& (active idle watchers, EVLOOP_NONBLOCK or not having |
|
|
852 | \& any active watchers at all will result in not sleeping). |
|
|
853 | \& \- Sleep if the I/O and timer collect interval say so. |
633 | \& - Block the process, waiting for any events. |
854 | \& \- Block the process, waiting for any events. |
634 | \& - Queue all outstanding I/O (fd) events. |
855 | \& \- Queue all outstanding I/O (fd) events. |
635 | \& - Update the "event loop time" and do time jump handling. |
856 | \& \- Update the "event loop time" (ev_now ()), and do time jump adjustments. |
636 | \& - Queue all outstanding timers. |
857 | \& \- Queue all expired timers. |
637 | \& - Queue all outstanding periodics. |
858 | \& \- Queue all expired periodics. |
638 | \& - If no events are pending now, queue all idle watchers. |
859 | \& \- Unless any events are pending now, queue all idle watchers. |
639 | \& - Queue all check watchers. |
860 | \& \- Queue all check watchers. |
640 | \& - Call all queued watchers in reverse order (i.e. check watchers first). |
861 | \& \- Call all queued watchers in reverse order (i.e. check watchers first). |
641 | \& Signals and child watchers are implemented as I/O watchers, and will |
862 | \& Signals and child watchers are implemented as I/O watchers, and will |
642 | \& be handled here by queueing them when their watcher gets executed. |
863 | \& be handled here by queueing them when their watcher gets executed. |
643 | \& - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
864 | \& \- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
644 | \& were used, return, otherwise continue with step *. |
865 | \& were used, or there are no active watchers, return, otherwise |
|
|
866 | \& continue with step *. |
645 | .Ve |
867 | .Ve |
646 | .Sp |
868 | .Sp |
647 | Example: Queue some jobs and then loop until no events are outsanding |
869 | Example: Queue some jobs and then loop until no events are outstanding |
648 | anymore. |
870 | anymore. |
649 | .Sp |
871 | .Sp |
650 | .Vb 4 |
872 | .Vb 4 |
651 | \& ... queue jobs here, make sure they register event watchers as long |
873 | \& ... queue jobs here, make sure they register event watchers as long |
652 | \& ... as they still have work to do (even an idle watcher will do..) |
874 | \& ... as they still have work to do (even an idle watcher will do..) |
653 | \& ev_loop (my_loop, 0); |
875 | \& ev_loop (my_loop, 0); |
654 | \& ... jobs done. yeah! |
876 | \& ... jobs done or somebody called unloop. yeah! |
655 | .Ve |
877 | .Ve |
656 | .IP "ev_unloop (loop, how)" 4 |
878 | .IP "ev_unloop (loop, how)" 4 |
657 | .IX Item "ev_unloop (loop, how)" |
879 | .IX Item "ev_unloop (loop, how)" |
658 | Can be used to make a call to \f(CW\*(C`ev_loop\*(C'\fR return early (but only after it |
880 | Can be used to make a call to \f(CW\*(C`ev_loop\*(C'\fR return early (but only after it |
659 | has processed all outstanding events). The \f(CW\*(C`how\*(C'\fR argument must be either |
881 | has processed all outstanding events). The \f(CW\*(C`how\*(C'\fR argument must be either |
660 | \&\f(CW\*(C`EVUNLOOP_ONE\*(C'\fR, which will make the innermost \f(CW\*(C`ev_loop\*(C'\fR call return, or |
882 | \&\f(CW\*(C`EVUNLOOP_ONE\*(C'\fR, which will make the innermost \f(CW\*(C`ev_loop\*(C'\fR call return, or |
661 | \&\f(CW\*(C`EVUNLOOP_ALL\*(C'\fR, which will make all nested \f(CW\*(C`ev_loop\*(C'\fR calls return. |
883 | \&\f(CW\*(C`EVUNLOOP_ALL\*(C'\fR, which will make all nested \f(CW\*(C`ev_loop\*(C'\fR calls return. |
|
|
884 | .Sp |
|
|
885 | This \*(L"unloop state\*(R" will be cleared when entering \f(CW\*(C`ev_loop\*(C'\fR again. |
|
|
886 | .Sp |
|
|
887 | It is safe to call \f(CW\*(C`ev_unloop\*(C'\fR from otuside any \f(CW\*(C`ev_loop\*(C'\fR calls. |
662 | .IP "ev_ref (loop)" 4 |
888 | .IP "ev_ref (loop)" 4 |
663 | .IX Item "ev_ref (loop)" |
889 | .IX Item "ev_ref (loop)" |
664 | .PD 0 |
890 | .PD 0 |
665 | .IP "ev_unref (loop)" 4 |
891 | .IP "ev_unref (loop)" 4 |
666 | .IX Item "ev_unref (loop)" |
892 | .IX Item "ev_unref (loop)" |
667 | .PD |
893 | .PD |
668 | Ref/unref can be used to add or remove a reference count on the event |
894 | Ref/unref can be used to add or remove a reference count on the event |
669 | loop: Every watcher keeps one reference, and as long as the reference |
895 | loop: Every watcher keeps one reference, and as long as the reference |
670 | count is nonzero, \f(CW\*(C`ev_loop\*(C'\fR will not return on its own. If you have |
896 | count is nonzero, \f(CW\*(C`ev_loop\*(C'\fR will not return on its own. |
|
|
897 | .Sp |
671 | a watcher you never unregister that should not keep \f(CW\*(C`ev_loop\*(C'\fR from |
898 | If you have a watcher you never unregister that should not keep \f(CW\*(C`ev_loop\*(C'\fR |
672 | returning, \fIev_unref()\fR after starting, and \fIev_ref()\fR before stopping it. For |
899 | from returning, call \fIev_unref()\fR after starting, and \fIev_ref()\fR before |
|
|
900 | stopping it. |
|
|
901 | .Sp |
673 | example, libev itself uses this for its internal signal pipe: It is not |
902 | As an example, libev itself uses this for its internal signal pipe: It |
674 | visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from exiting if |
903 | is not visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from |
675 | no event watchers registered by it are active. It is also an excellent |
904 | exiting if no event watchers registered by it are active. It is also an |
676 | way to do this for generic recurring timers or from within third-party |
905 | excellent way to do this for generic recurring timers or from within |
677 | libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR. |
906 | third-party libraries. Just remember to \fIunref after start\fR and \fIref |
|
|
907 | before stop\fR (but only if the watcher wasn't active before, or was active |
|
|
908 | before, respectively. Note also that libev might stop watchers itself |
|
|
909 | (e.g. non-repeating timers) in which case you have to \f(CW\*(C`ev_ref\*(C'\fR |
|
|
910 | in the callback). |
678 | .Sp |
911 | .Sp |
679 | Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR |
912 | Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR |
680 | running when nothing else is active. |
913 | running when nothing else is active. |
681 | .Sp |
914 | .Sp |
682 | .Vb 4 |
915 | .Vb 4 |
683 | \& struct ev_signal exitsig; |
916 | \& ev_signal exitsig; |
684 | \& ev_signal_init (&exitsig, sig_cb, SIGINT); |
917 | \& ev_signal_init (&exitsig, sig_cb, SIGINT); |
685 | \& ev_signal_start (loop, &exitsig); |
918 | \& ev_signal_start (loop, &exitsig); |
686 | \& evf_unref (loop); |
919 | \& evf_unref (loop); |
687 | .Ve |
920 | .Ve |
688 | .Sp |
921 | .Sp |
689 | Example: For some weird reason, unregister the above signal handler again. |
922 | Example: For some weird reason, unregister the above signal handler again. |
690 | .Sp |
923 | .Sp |
691 | .Vb 2 |
924 | .Vb 2 |
692 | \& ev_ref (loop); |
925 | \& ev_ref (loop); |
693 | \& ev_signal_stop (loop, &exitsig); |
926 | \& ev_signal_stop (loop, &exitsig); |
694 | .Ve |
927 | .Ve |
|
|
928 | .IP "ev_set_io_collect_interval (loop, ev_tstamp interval)" 4 |
|
|
929 | .IX Item "ev_set_io_collect_interval (loop, ev_tstamp interval)" |
|
|
930 | .PD 0 |
|
|
931 | .IP "ev_set_timeout_collect_interval (loop, ev_tstamp interval)" 4 |
|
|
932 | .IX Item "ev_set_timeout_collect_interval (loop, ev_tstamp interval)" |
|
|
933 | .PD |
|
|
934 | These advanced functions influence the time that libev will spend waiting |
|
|
935 | for events. Both time intervals are by default \f(CW0\fR, meaning that libev |
|
|
936 | will try to invoke timer/periodic callbacks and I/O callbacks with minimum |
|
|
937 | latency. |
|
|
938 | .Sp |
|
|
939 | Setting these to a higher value (the \f(CW\*(C`interval\*(C'\fR \fImust\fR be >= \f(CW0\fR) |
|
|
940 | allows libev to delay invocation of I/O and timer/periodic callbacks |
|
|
941 | to increase efficiency of loop iterations (or to increase power-saving |
|
|
942 | opportunities). |
|
|
943 | .Sp |
|
|
944 | The idea is that sometimes your program runs just fast enough to handle |
|
|
945 | one (or very few) event(s) per loop iteration. While this makes the |
|
|
946 | program responsive, it also wastes a lot of \s-1CPU\s0 time to poll for new |
|
|
947 | events, especially with backends like \f(CW\*(C`select ()\*(C'\fR which have a high |
|
|
948 | overhead for the actual polling but can deliver many events at once. |
|
|
949 | .Sp |
|
|
950 | By setting a higher \fIio collect interval\fR you allow libev to spend more |
|
|
951 | time collecting I/O events, so you can handle more events per iteration, |
|
|
952 | at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and |
|
|
953 | \&\f(CW\*(C`ev_timer\*(C'\fR) will be not affected. Setting this to a non-null value will |
|
|
954 | introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations. The |
|
|
955 | sleep time ensures that libev will not poll for I/O events more often then |
|
|
956 | once per this interval, on average. |
|
|
957 | .Sp |
|
|
958 | Likewise, by setting a higher \fItimeout collect interval\fR you allow libev |
|
|
959 | to spend more time collecting timeouts, at the expense of increased |
|
|
960 | latency/jitter/inexactness (the watcher callback will be called |
|
|
961 | later). \f(CW\*(C`ev_io\*(C'\fR watchers will not be affected. Setting this to a non-null |
|
|
962 | value will not introduce any overhead in libev. |
|
|
963 | .Sp |
|
|
964 | Many (busy) programs can usually benefit by setting the I/O collect |
|
|
965 | interval to a value near \f(CW0.1\fR or so, which is often enough for |
|
|
966 | interactive servers (of course not for games), likewise for timeouts. It |
|
|
967 | usually doesn't make much sense to set it to a lower value than \f(CW0.01\fR, |
|
|
968 | as this approaches the timing granularity of most systems. Note that if |
|
|
969 | you do transactions with the outside world and you can't increase the |
|
|
970 | parallelity, then this setting will limit your transaction rate (if you |
|
|
971 | need to poll once per transaction and the I/O collect interval is 0.01, |
|
|
972 | then you can't do more than 100 transations per second). |
|
|
973 | .Sp |
|
|
974 | Setting the \fItimeout collect interval\fR can improve the opportunity for |
|
|
975 | saving power, as the program will \*(L"bundle\*(R" timer callback invocations that |
|
|
976 | are \*(L"near\*(R" in time together, by delaying some, thus reducing the number of |
|
|
977 | times the process sleeps and wakes up again. Another useful technique to |
|
|
978 | reduce iterations/wake\-ups is to use \f(CW\*(C`ev_periodic\*(C'\fR watchers and make sure |
|
|
979 | they fire on, say, one-second boundaries only. |
|
|
980 | .Sp |
|
|
981 | Example: we only need 0.1s timeout granularity, and we wish not to poll |
|
|
982 | more often than 100 times per second: |
|
|
983 | .Sp |
|
|
984 | .Vb 2 |
|
|
985 | \& ev_set_timeout_collect_interval (EV_DEFAULT_UC_ 0.1); |
|
|
986 | \& ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
|
|
987 | .Ve |
|
|
988 | .IP "ev_invoke_pending (loop)" 4 |
|
|
989 | .IX Item "ev_invoke_pending (loop)" |
|
|
990 | This call will simply invoke all pending watchers while resetting their |
|
|
991 | pending state. Normally, \f(CW\*(C`ev_loop\*(C'\fR does this automatically when required, |
|
|
992 | but when overriding the invoke callback this call comes handy. |
|
|
993 | .IP "int ev_pending_count (loop)" 4 |
|
|
994 | .IX Item "int ev_pending_count (loop)" |
|
|
995 | Returns the number of pending watchers \- zero indicates that no watchers |
|
|
996 | are pending. |
|
|
997 | .IP "ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(\s-1EV_P\s0))" 4 |
|
|
998 | .IX Item "ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))" |
|
|
999 | This overrides the invoke pending functionality of the loop: Instead of |
|
|
1000 | invoking all pending watchers when there are any, \f(CW\*(C`ev_loop\*(C'\fR will call |
|
|
1001 | this callback instead. This is useful, for example, when you want to |
|
|
1002 | invoke the actual watchers inside another context (another thread etc.). |
|
|
1003 | .Sp |
|
|
1004 | If you want to reset the callback, use \f(CW\*(C`ev_invoke_pending\*(C'\fR as new |
|
|
1005 | callback. |
|
|
1006 | .IP "ev_set_loop_release_cb (loop, void (*release)(\s-1EV_P\s0), void (*acquire)(\s-1EV_P\s0))" 4 |
|
|
1007 | .IX Item "ev_set_loop_release_cb (loop, void (*release)(EV_P), void (*acquire)(EV_P))" |
|
|
1008 | Sometimes you want to share the same loop between multiple threads. This |
|
|
1009 | can be done relatively simply by putting mutex_lock/unlock calls around |
|
|
1010 | each call to a libev function. |
|
|
1011 | .Sp |
|
|
1012 | However, \f(CW\*(C`ev_loop\*(C'\fR can run an indefinite time, so it is not feasible to |
|
|
1013 | wait for it to return. One way around this is to wake up the loop via |
|
|
1014 | \&\f(CW\*(C`ev_unloop\*(C'\fR and \f(CW\*(C`av_async_send\*(C'\fR, another way is to set these \fIrelease\fR |
|
|
1015 | and \fIacquire\fR callbacks on the loop. |
|
|
1016 | .Sp |
|
|
1017 | When set, then \f(CW\*(C`release\*(C'\fR will be called just before the thread is |
|
|
1018 | suspended waiting for new events, and \f(CW\*(C`acquire\*(C'\fR is called just |
|
|
1019 | afterwards. |
|
|
1020 | .Sp |
|
|
1021 | Ideally, \f(CW\*(C`release\*(C'\fR will just call your mutex_unlock function, and |
|
|
1022 | \&\f(CW\*(C`acquire\*(C'\fR will just call the mutex_lock function again. |
|
|
1023 | .Sp |
|
|
1024 | While event loop modifications are allowed between invocations of |
|
|
1025 | \&\f(CW\*(C`release\*(C'\fR and \f(CW\*(C`acquire\*(C'\fR (that's their only purpose after all), no |
|
|
1026 | modifications done will affect the event loop, i.e. adding watchers will |
|
|
1027 | have no effect on the set of file descriptors being watched, or the time |
|
|
1028 | waited. USe an \f(CW\*(C`ev_async\*(C'\fR watcher to wake up \f(CW\*(C`ev_loop\*(C'\fR when you want it |
|
|
1029 | to take note of any changes you made. |
|
|
1030 | .Sp |
|
|
1031 | In theory, threads executing \f(CW\*(C`ev_loop\*(C'\fR will be async-cancel safe between |
|
|
1032 | invocations of \f(CW\*(C`release\*(C'\fR and \f(CW\*(C`acquire\*(C'\fR. |
|
|
1033 | .Sp |
|
|
1034 | See also the locking example in the \f(CW\*(C`THREADS\*(C'\fR section later in this |
|
|
1035 | document. |
|
|
1036 | .IP "ev_set_userdata (loop, void *data)" 4 |
|
|
1037 | .IX Item "ev_set_userdata (loop, void *data)" |
|
|
1038 | .PD 0 |
|
|
1039 | .IP "ev_userdata (loop)" 4 |
|
|
1040 | .IX Item "ev_userdata (loop)" |
|
|
1041 | .PD |
|
|
1042 | Set and retrieve a single \f(CW\*(C`void *\*(C'\fR associated with a loop. When |
|
|
1043 | \&\f(CW\*(C`ev_set_userdata\*(C'\fR has never been called, then \f(CW\*(C`ev_userdata\*(C'\fR returns |
|
|
1044 | \&\f(CW0.\fR |
|
|
1045 | .Sp |
|
|
1046 | These two functions can be used to associate arbitrary data with a loop, |
|
|
1047 | and are intended solely for the \f(CW\*(C`invoke_pending_cb\*(C'\fR, \f(CW\*(C`release\*(C'\fR and |
|
|
1048 | \&\f(CW\*(C`acquire\*(C'\fR callbacks described above, but of course can be (ab\-)used for |
|
|
1049 | any other purpose as well. |
|
|
1050 | .IP "ev_loop_verify (loop)" 4 |
|
|
1051 | .IX Item "ev_loop_verify (loop)" |
|
|
1052 | This function only does something when \f(CW\*(C`EV_VERIFY\*(C'\fR support has been |
|
|
1053 | compiled in, which is the default for non-minimal builds. It tries to go |
|
|
1054 | through all internal structures and checks them for validity. If anything |
|
|
1055 | is found to be inconsistent, it will print an error message to standard |
|
|
1056 | error and call \f(CW\*(C`abort ()\*(C'\fR. |
|
|
1057 | .Sp |
|
|
1058 | This can be used to catch bugs inside libev itself: under normal |
|
|
1059 | circumstances, this function will never abort as of course libev keeps its |
|
|
1060 | data structures consistent. |
695 | .SH "ANATOMY OF A WATCHER" |
1061 | .SH "ANATOMY OF A WATCHER" |
696 | .IX Header "ANATOMY OF A WATCHER" |
1062 | .IX Header "ANATOMY OF A WATCHER" |
|
|
1063 | In the following description, uppercase \f(CW\*(C`TYPE\*(C'\fR in names stands for the |
|
|
1064 | watcher type, e.g. \f(CW\*(C`ev_TYPE_start\*(C'\fR can mean \f(CW\*(C`ev_timer_start\*(C'\fR for timer |
|
|
1065 | watchers and \f(CW\*(C`ev_io_start\*(C'\fR for I/O watchers. |
|
|
1066 | .PP |
697 | A watcher is a structure that you create and register to record your |
1067 | A watcher is a structure that you create and register to record your |
698 | interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to |
1068 | interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to |
699 | become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher for that: |
1069 | become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher for that: |
700 | .PP |
1070 | .PP |
701 | .Vb 5 |
1071 | .Vb 5 |
702 | \& static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1072 | \& static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
703 | \& { |
1073 | \& { |
704 | \& ev_io_stop (w); |
1074 | \& ev_io_stop (w); |
705 | \& ev_unloop (loop, EVUNLOOP_ALL); |
1075 | \& ev_unloop (loop, EVUNLOOP_ALL); |
706 | \& } |
1076 | \& } |
707 | .Ve |
1077 | \& |
708 | .PP |
|
|
709 | .Vb 6 |
|
|
710 | \& struct ev_loop *loop = ev_default_loop (0); |
1078 | \& struct ev_loop *loop = ev_default_loop (0); |
|
|
1079 | \& |
711 | \& struct ev_io stdin_watcher; |
1080 | \& ev_io stdin_watcher; |
|
|
1081 | \& |
712 | \& ev_init (&stdin_watcher, my_cb); |
1082 | \& ev_init (&stdin_watcher, my_cb); |
713 | \& ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
1083 | \& ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
714 | \& ev_io_start (loop, &stdin_watcher); |
1084 | \& ev_io_start (loop, &stdin_watcher); |
|
|
1085 | \& |
715 | \& ev_loop (loop, 0); |
1086 | \& ev_loop (loop, 0); |
716 | .Ve |
1087 | .Ve |
717 | .PP |
1088 | .PP |
718 | As you can see, you are responsible for allocating the memory for your |
1089 | As you can see, you are responsible for allocating the memory for your |
719 | watcher structures (and it is usually a bad idea to do this on the stack, |
1090 | watcher structures (and it is \fIusually\fR a bad idea to do this on the |
720 | although this can sometimes be quite valid). |
1091 | stack). |
|
|
1092 | .PP |
|
|
1093 | Each watcher has an associated watcher structure (called \f(CW\*(C`struct ev_TYPE\*(C'\fR |
|
|
1094 | or simply \f(CW\*(C`ev_TYPE\*(C'\fR, as typedefs are provided for all watcher structs). |
721 | .PP |
1095 | .PP |
722 | Each watcher structure must be initialised by a call to \f(CW\*(C`ev_init |
1096 | Each watcher structure must be initialised by a call to \f(CW\*(C`ev_init |
723 | (watcher *, callback)\*(C'\fR, which expects a callback to be provided. This |
1097 | (watcher *, callback)\*(C'\fR, which expects a callback to be provided. This |
724 | callback gets invoked each time the event occurs (or, in the case of io |
1098 | callback gets invoked each time the event occurs (or, in the case of I/O |
725 | watchers, each time the event loop detects that the file descriptor given |
1099 | watchers, each time the event loop detects that the file descriptor given |
726 | is readable and/or writable). |
1100 | is readable and/or writable). |
727 | .PP |
1101 | .PP |
728 | Each watcher type has its own \f(CW\*(C`ev_<type>_set (watcher *, ...)\*(C'\fR macro |
1102 | Each watcher type further has its own \f(CW\*(C`ev_TYPE_set (watcher *, ...)\*(C'\fR |
729 | with arguments specific to this watcher type. There is also a macro |
1103 | macro to configure it, with arguments specific to the watcher type. There |
730 | to combine initialisation and setting in one call: \f(CW\*(C`ev_<type>_init |
1104 | is also a macro to combine initialisation and setting in one call: \f(CW\*(C`ev_TYPE_init (watcher *, callback, ...)\*(C'\fR. |
731 | (watcher *, callback, ...)\*(C'\fR. |
|
|
732 | .PP |
1105 | .PP |
733 | To make the watcher actually watch out for events, you have to start it |
1106 | To make the watcher actually watch out for events, you have to start it |
734 | with a watcher-specific start function (\f(CW\*(C`ev_<type>_start (loop, watcher |
1107 | with a watcher-specific start function (\f(CW\*(C`ev_TYPE_start (loop, watcher |
735 | *)\*(C'\fR), and you can stop watching for events at any time by calling the |
1108 | *)\*(C'\fR), and you can stop watching for events at any time by calling the |
736 | corresponding stop function (\f(CW\*(C`ev_<type>_stop (loop, watcher *)\*(C'\fR. |
1109 | corresponding stop function (\f(CW\*(C`ev_TYPE_stop (loop, watcher *)\*(C'\fR. |
737 | .PP |
1110 | .PP |
738 | As long as your watcher is active (has been started but not stopped) you |
1111 | As long as your watcher is active (has been started but not stopped) you |
739 | must not touch the values stored in it. Most specifically you must never |
1112 | must not touch the values stored in it. Most specifically you must never |
740 | reinitialise it or call its \f(CW\*(C`set\*(C'\fR macro. |
1113 | reinitialise it or call its \f(CW\*(C`ev_TYPE_set\*(C'\fR macro. |
741 | .PP |
1114 | .PP |
742 | Each and every callback receives the event loop pointer as first, the |
1115 | Each and every callback receives the event loop pointer as first, the |
743 | registered watcher structure as second, and a bitset of received events as |
1116 | registered watcher structure as second, and a bitset of received events as |
744 | third argument. |
1117 | third argument. |
745 | .PP |
1118 | .PP |
… | |
… | |
802 | .ie n .IP """EV_FORK""" 4 |
1175 | .ie n .IP """EV_FORK""" 4 |
803 | .el .IP "\f(CWEV_FORK\fR" 4 |
1176 | .el .IP "\f(CWEV_FORK\fR" 4 |
804 | .IX Item "EV_FORK" |
1177 | .IX Item "EV_FORK" |
805 | The event loop has been resumed in the child process after fork (see |
1178 | The event loop has been resumed in the child process after fork (see |
806 | \&\f(CW\*(C`ev_fork\*(C'\fR). |
1179 | \&\f(CW\*(C`ev_fork\*(C'\fR). |
|
|
1180 | .ie n .IP """EV_ASYNC""" 4 |
|
|
1181 | .el .IP "\f(CWEV_ASYNC\fR" 4 |
|
|
1182 | .IX Item "EV_ASYNC" |
|
|
1183 | The given async watcher has been asynchronously notified (see \f(CW\*(C`ev_async\*(C'\fR). |
|
|
1184 | .ie n .IP """EV_CUSTOM""" 4 |
|
|
1185 | .el .IP "\f(CWEV_CUSTOM\fR" 4 |
|
|
1186 | .IX Item "EV_CUSTOM" |
|
|
1187 | Not ever sent (or otherwise used) by libev itself, but can be freely used |
|
|
1188 | by libev users to signal watchers (e.g. via \f(CW\*(C`ev_feed_event\*(C'\fR). |
807 | .ie n .IP """EV_ERROR""" 4 |
1189 | .ie n .IP """EV_ERROR""" 4 |
808 | .el .IP "\f(CWEV_ERROR\fR" 4 |
1190 | .el .IP "\f(CWEV_ERROR\fR" 4 |
809 | .IX Item "EV_ERROR" |
1191 | .IX Item "EV_ERROR" |
810 | An unspecified error has occured, the watcher has been stopped. This might |
1192 | An unspecified error has occurred, the watcher has been stopped. This might |
811 | happen because the watcher could not be properly started because libev |
1193 | happen because the watcher could not be properly started because libev |
812 | ran out of memory, a file descriptor was found to be closed or any other |
1194 | ran out of memory, a file descriptor was found to be closed or any other |
|
|
1195 | problem. Libev considers these application bugs. |
|
|
1196 | .Sp |
813 | problem. You best act on it by reporting the problem and somehow coping |
1197 | You best act on it by reporting the problem and somehow coping with the |
814 | with the watcher being stopped. |
1198 | watcher being stopped. Note that well-written programs should not receive |
|
|
1199 | an error ever, so when your watcher receives it, this usually indicates a |
|
|
1200 | bug in your program. |
815 | .Sp |
1201 | .Sp |
816 | Libev will usually signal a few \*(L"dummy\*(R" events together with an error, |
1202 | Libev will usually signal a few \*(L"dummy\*(R" events together with an error, for |
817 | for example it might indicate that a fd is readable or writable, and if |
1203 | example it might indicate that a fd is readable or writable, and if your |
818 | your callbacks is well-written it can just attempt the operation and cope |
1204 | callbacks is well-written it can just attempt the operation and cope with |
819 | with the error from \fIread()\fR or \fIwrite()\fR. This will not work in multithreaded |
1205 | the error from \fIread()\fR or \fIwrite()\fR. This will not work in multi-threaded |
820 | programs, though, so beware. |
1206 | programs, though, as the fd could already be closed and reused for another |
|
|
1207 | thing, so beware. |
821 | .Sh "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0" |
1208 | .SS "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0" |
822 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
1209 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
823 | In the following description, \f(CW\*(C`TYPE\*(C'\fR stands for the watcher type, |
|
|
824 | e.g. \f(CW\*(C`timer\*(C'\fR for \f(CW\*(C`ev_timer\*(C'\fR watchers and \f(CW\*(C`io\*(C'\fR for \f(CW\*(C`ev_io\*(C'\fR watchers. |
|
|
825 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
1210 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
826 | .el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 |
1211 | .el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 |
827 | .IX Item "ev_init (ev_TYPE *watcher, callback)" |
1212 | .IX Item "ev_init (ev_TYPE *watcher, callback)" |
828 | This macro initialises the generic portion of a watcher. The contents |
1213 | This macro initialises the generic portion of a watcher. The contents |
829 | of the watcher object can be arbitrary (so \f(CW\*(C`malloc\*(C'\fR will do). Only |
1214 | of the watcher object can be arbitrary (so \f(CW\*(C`malloc\*(C'\fR will do). Only |
… | |
… | |
833 | which rolls both calls into one. |
1218 | which rolls both calls into one. |
834 | .Sp |
1219 | .Sp |
835 | You can reinitialise a watcher at any time as long as it has been stopped |
1220 | You can reinitialise a watcher at any time as long as it has been stopped |
836 | (or never started) and there are no pending events outstanding. |
1221 | (or never started) and there are no pending events outstanding. |
837 | .Sp |
1222 | .Sp |
838 | The callback is always of type \f(CW\*(C`void (*)(ev_loop *loop, ev_TYPE *watcher, |
1223 | The callback is always of type \f(CW\*(C`void (*)(struct ev_loop *loop, ev_TYPE *watcher, |
839 | int revents)\*(C'\fR. |
1224 | int revents)\*(C'\fR. |
|
|
1225 | .Sp |
|
|
1226 | Example: Initialise an \f(CW\*(C`ev_io\*(C'\fR watcher in two steps. |
|
|
1227 | .Sp |
|
|
1228 | .Vb 3 |
|
|
1229 | \& ev_io w; |
|
|
1230 | \& ev_init (&w, my_cb); |
|
|
1231 | \& ev_io_set (&w, STDIN_FILENO, EV_READ); |
|
|
1232 | .Ve |
840 | .ie n .IP """ev_TYPE_set"" (ev_TYPE *, [args])" 4 |
1233 | .ie n .IP """ev_TYPE_set"" (ev_TYPE *, [args])" 4 |
841 | .el .IP "\f(CWev_TYPE_set\fR (ev_TYPE *, [args])" 4 |
1234 | .el .IP "\f(CWev_TYPE_set\fR (ev_TYPE *, [args])" 4 |
842 | .IX Item "ev_TYPE_set (ev_TYPE *, [args])" |
1235 | .IX Item "ev_TYPE_set (ev_TYPE *, [args])" |
843 | This macro initialises the type-specific parts of a watcher. You need to |
1236 | This macro initialises the type-specific parts of a watcher. You need to |
844 | call \f(CW\*(C`ev_init\*(C'\fR at least once before you call this macro, but you can |
1237 | call \f(CW\*(C`ev_init\*(C'\fR at least once before you call this macro, but you can |
… | |
… | |
846 | macro on a watcher that is active (it can be pending, however, which is a |
1239 | macro on a watcher that is active (it can be pending, however, which is a |
847 | difference to the \f(CW\*(C`ev_init\*(C'\fR macro). |
1240 | difference to the \f(CW\*(C`ev_init\*(C'\fR macro). |
848 | .Sp |
1241 | .Sp |
849 | Although some watcher types do not have type-specific arguments |
1242 | Although some watcher types do not have type-specific arguments |
850 | (e.g. \f(CW\*(C`ev_prepare\*(C'\fR) you still need to call its \f(CW\*(C`set\*(C'\fR macro. |
1243 | (e.g. \f(CW\*(C`ev_prepare\*(C'\fR) you still need to call its \f(CW\*(C`set\*(C'\fR macro. |
|
|
1244 | .Sp |
|
|
1245 | See \f(CW\*(C`ev_init\*(C'\fR, above, for an example. |
851 | .ie n .IP """ev_TYPE_init"" (ev_TYPE *watcher, callback, [args])" 4 |
1246 | .ie n .IP """ev_TYPE_init"" (ev_TYPE *watcher, callback, [args])" 4 |
852 | .el .IP "\f(CWev_TYPE_init\fR (ev_TYPE *watcher, callback, [args])" 4 |
1247 | .el .IP "\f(CWev_TYPE_init\fR (ev_TYPE *watcher, callback, [args])" 4 |
853 | .IX Item "ev_TYPE_init (ev_TYPE *watcher, callback, [args])" |
1248 | .IX Item "ev_TYPE_init (ev_TYPE *watcher, callback, [args])" |
854 | This convinience macro rolls both \f(CW\*(C`ev_init\*(C'\fR and \f(CW\*(C`ev_TYPE_set\*(C'\fR macro |
1249 | This convenience macro rolls both \f(CW\*(C`ev_init\*(C'\fR and \f(CW\*(C`ev_TYPE_set\*(C'\fR macro |
855 | calls into a single call. This is the most convinient method to initialise |
1250 | calls into a single call. This is the most convenient method to initialise |
856 | a watcher. The same limitations apply, of course. |
1251 | a watcher. The same limitations apply, of course. |
|
|
1252 | .Sp |
|
|
1253 | Example: Initialise and set an \f(CW\*(C`ev_io\*(C'\fR watcher in one step. |
|
|
1254 | .Sp |
|
|
1255 | .Vb 1 |
|
|
1256 | \& ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
|
|
1257 | .Ve |
857 | .ie n .IP """ev_TYPE_start"" (loop *, ev_TYPE *watcher)" 4 |
1258 | .ie n .IP """ev_TYPE_start"" (loop *, ev_TYPE *watcher)" 4 |
858 | .el .IP "\f(CWev_TYPE_start\fR (loop *, ev_TYPE *watcher)" 4 |
1259 | .el .IP "\f(CWev_TYPE_start\fR (loop *, ev_TYPE *watcher)" 4 |
859 | .IX Item "ev_TYPE_start (loop *, ev_TYPE *watcher)" |
1260 | .IX Item "ev_TYPE_start (loop *, ev_TYPE *watcher)" |
860 | Starts (activates) the given watcher. Only active watchers will receive |
1261 | Starts (activates) the given watcher. Only active watchers will receive |
861 | events. If the watcher is already active nothing will happen. |
1262 | events. If the watcher is already active nothing will happen. |
|
|
1263 | .Sp |
|
|
1264 | Example: Start the \f(CW\*(C`ev_io\*(C'\fR watcher that is being abused as example in this |
|
|
1265 | whole section. |
|
|
1266 | .Sp |
|
|
1267 | .Vb 1 |
|
|
1268 | \& ev_io_start (EV_DEFAULT_UC, &w); |
|
|
1269 | .Ve |
862 | .ie n .IP """ev_TYPE_stop"" (loop *, ev_TYPE *watcher)" 4 |
1270 | .ie n .IP """ev_TYPE_stop"" (loop *, ev_TYPE *watcher)" 4 |
863 | .el .IP "\f(CWev_TYPE_stop\fR (loop *, ev_TYPE *watcher)" 4 |
1271 | .el .IP "\f(CWev_TYPE_stop\fR (loop *, ev_TYPE *watcher)" 4 |
864 | .IX Item "ev_TYPE_stop (loop *, ev_TYPE *watcher)" |
1272 | .IX Item "ev_TYPE_stop (loop *, ev_TYPE *watcher)" |
865 | Stops the given watcher again (if active) and clears the pending |
1273 | Stops the given watcher if active, and clears the pending status (whether |
|
|
1274 | the watcher was active or not). |
|
|
1275 | .Sp |
866 | status. It is possible that stopped watchers are pending (for example, |
1276 | It is possible that stopped watchers are pending \- for example, |
867 | non-repeating timers are being stopped when they become pending), but |
1277 | non-repeating timers are being stopped when they become pending \- but |
868 | \&\f(CW\*(C`ev_TYPE_stop\*(C'\fR ensures that the watcher is neither active nor pending. If |
1278 | calling \f(CW\*(C`ev_TYPE_stop\*(C'\fR ensures that the watcher is neither active nor |
869 | you want to free or reuse the memory used by the watcher it is therefore a |
1279 | pending. If you want to free or reuse the memory used by the watcher it is |
870 | good idea to always call its \f(CW\*(C`ev_TYPE_stop\*(C'\fR function. |
1280 | therefore a good idea to always call its \f(CW\*(C`ev_TYPE_stop\*(C'\fR function. |
871 | .IP "bool ev_is_active (ev_TYPE *watcher)" 4 |
1281 | .IP "bool ev_is_active (ev_TYPE *watcher)" 4 |
872 | .IX Item "bool ev_is_active (ev_TYPE *watcher)" |
1282 | .IX Item "bool ev_is_active (ev_TYPE *watcher)" |
873 | Returns a true value iff the watcher is active (i.e. it has been started |
1283 | Returns a true value iff the watcher is active (i.e. it has been started |
874 | and not yet been stopped). As long as a watcher is active you must not modify |
1284 | and not yet been stopped). As long as a watcher is active you must not modify |
875 | it. |
1285 | it. |
876 | .IP "bool ev_is_pending (ev_TYPE *watcher)" 4 |
1286 | .IP "bool ev_is_pending (ev_TYPE *watcher)" 4 |
877 | .IX Item "bool ev_is_pending (ev_TYPE *watcher)" |
1287 | .IX Item "bool ev_is_pending (ev_TYPE *watcher)" |
878 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
1288 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
879 | events but its callback has not yet been invoked). As long as a watcher |
1289 | events but its callback has not yet been invoked). As long as a watcher |
880 | is pending (but not active) you must not call an init function on it (but |
1290 | is pending (but not active) you must not call an init function on it (but |
881 | \&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe) and you must make sure the watcher is available to |
1291 | \&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe), you must not change its priority, and you must |
882 | libev (e.g. you cnanot \f(CW\*(C`free ()\*(C'\fR it). |
1292 | make sure the watcher is available to libev (e.g. you cannot \f(CW\*(C`free ()\*(C'\fR |
|
|
1293 | it). |
883 | .IP "callback ev_cb (ev_TYPE *watcher)" 4 |
1294 | .IP "callback ev_cb (ev_TYPE *watcher)" 4 |
884 | .IX Item "callback ev_cb (ev_TYPE *watcher)" |
1295 | .IX Item "callback ev_cb (ev_TYPE *watcher)" |
885 | Returns the callback currently set on the watcher. |
1296 | Returns the callback currently set on the watcher. |
886 | .IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 |
1297 | .IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 |
887 | .IX Item "ev_cb_set (ev_TYPE *watcher, callback)" |
1298 | .IX Item "ev_cb_set (ev_TYPE *watcher, callback)" |
888 | Change the callback. You can change the callback at virtually any time |
1299 | Change the callback. You can change the callback at virtually any time |
889 | (modulo threads). |
1300 | (modulo threads). |
|
|
1301 | .IP "ev_set_priority (ev_TYPE *watcher, priority)" 4 |
|
|
1302 | .IX Item "ev_set_priority (ev_TYPE *watcher, priority)" |
|
|
1303 | .PD 0 |
|
|
1304 | .IP "int ev_priority (ev_TYPE *watcher)" 4 |
|
|
1305 | .IX Item "int ev_priority (ev_TYPE *watcher)" |
|
|
1306 | .PD |
|
|
1307 | Set and query the priority of the watcher. The priority is a small |
|
|
1308 | integer between \f(CW\*(C`EV_MAXPRI\*(C'\fR (default: \f(CW2\fR) and \f(CW\*(C`EV_MINPRI\*(C'\fR |
|
|
1309 | (default: \f(CW\*(C`\-2\*(C'\fR). Pending watchers with higher priority will be invoked |
|
|
1310 | before watchers with lower priority, but priority will not keep watchers |
|
|
1311 | from being executed (except for \f(CW\*(C`ev_idle\*(C'\fR watchers). |
|
|
1312 | .Sp |
|
|
1313 | If you need to suppress invocation when higher priority events are pending |
|
|
1314 | you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality. |
|
|
1315 | .Sp |
|
|
1316 | You \fImust not\fR change the priority of a watcher as long as it is active or |
|
|
1317 | pending. |
|
|
1318 | .Sp |
|
|
1319 | Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is |
|
|
1320 | fine, as long as you do not mind that the priority value you query might |
|
|
1321 | or might not have been clamped to the valid range. |
|
|
1322 | .Sp |
|
|
1323 | The default priority used by watchers when no priority has been set is |
|
|
1324 | always \f(CW0\fR, which is supposed to not be too high and not be too low :). |
|
|
1325 | .Sp |
|
|
1326 | See \*(L"\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0\*(R", below, for a more thorough treatment of |
|
|
1327 | priorities. |
|
|
1328 | .IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4 |
|
|
1329 | .IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)" |
|
|
1330 | Invoke the \f(CW\*(C`watcher\*(C'\fR with the given \f(CW\*(C`loop\*(C'\fR and \f(CW\*(C`revents\*(C'\fR. Neither |
|
|
1331 | \&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback |
|
|
1332 | can deal with that fact, as both are simply passed through to the |
|
|
1333 | callback. |
|
|
1334 | .IP "int ev_clear_pending (loop, ev_TYPE *watcher)" 4 |
|
|
1335 | .IX Item "int ev_clear_pending (loop, ev_TYPE *watcher)" |
|
|
1336 | If the watcher is pending, this function clears its pending status and |
|
|
1337 | returns its \f(CW\*(C`revents\*(C'\fR bitset (as if its callback was invoked). If the |
|
|
1338 | watcher isn't pending it does nothing and returns \f(CW0\fR. |
|
|
1339 | .Sp |
|
|
1340 | Sometimes it can be useful to \*(L"poll\*(R" a watcher instead of waiting for its |
|
|
1341 | callback to be invoked, which can be accomplished with this function. |
890 | .Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" |
1342 | .SS "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" |
891 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
1343 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
892 | Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change |
1344 | Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change |
893 | and read at any time, libev will completely ignore it. This can be used |
1345 | and read at any time: libev will completely ignore it. This can be used |
894 | to associate arbitrary data with your watcher. If you need more data and |
1346 | to associate arbitrary data with your watcher. If you need more data and |
895 | don't want to allocate memory and store a pointer to it in that data |
1347 | don't want to allocate memory and store a pointer to it in that data |
896 | member, you can also \*(L"subclass\*(R" the watcher type and provide your own |
1348 | member, you can also \*(L"subclass\*(R" the watcher type and provide your own |
897 | data: |
1349 | data: |
898 | .PP |
1350 | .PP |
899 | .Vb 7 |
1351 | .Vb 7 |
900 | \& struct my_io |
1352 | \& struct my_io |
901 | \& { |
1353 | \& { |
902 | \& struct ev_io io; |
1354 | \& ev_io io; |
903 | \& int otherfd; |
1355 | \& int otherfd; |
904 | \& void *somedata; |
1356 | \& void *somedata; |
905 | \& struct whatever *mostinteresting; |
1357 | \& struct whatever *mostinteresting; |
906 | \& } |
1358 | \& }; |
|
|
1359 | \& |
|
|
1360 | \& ... |
|
|
1361 | \& struct my_io w; |
|
|
1362 | \& ev_io_init (&w.io, my_cb, fd, EV_READ); |
907 | .Ve |
1363 | .Ve |
908 | .PP |
1364 | .PP |
909 | And since your callback will be called with a pointer to the watcher, you |
1365 | And since your callback will be called with a pointer to the watcher, you |
910 | can cast it back to your own type: |
1366 | can cast it back to your own type: |
911 | .PP |
1367 | .PP |
912 | .Vb 5 |
1368 | .Vb 5 |
913 | \& static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents) |
1369 | \& static void my_cb (struct ev_loop *loop, ev_io *w_, int revents) |
914 | \& { |
1370 | \& { |
915 | \& struct my_io *w = (struct my_io *)w_; |
1371 | \& struct my_io *w = (struct my_io *)w_; |
916 | \& ... |
1372 | \& ... |
917 | \& } |
1373 | \& } |
918 | .Ve |
1374 | .Ve |
919 | .PP |
1375 | .PP |
920 | More interesting and less C\-conformant ways of casting your callback type |
1376 | More interesting and less C\-conformant ways of casting your callback type |
921 | instead have been omitted. |
1377 | instead have been omitted. |
922 | .PP |
1378 | .PP |
923 | Another common scenario is having some data structure with multiple |
1379 | Another common scenario is to use some data structure with multiple |
924 | watchers: |
1380 | embedded watchers: |
925 | .PP |
1381 | .PP |
926 | .Vb 6 |
1382 | .Vb 6 |
927 | \& struct my_biggy |
1383 | \& struct my_biggy |
928 | \& { |
1384 | \& { |
929 | \& int some_data; |
1385 | \& int some_data; |
930 | \& ev_timer t1; |
1386 | \& ev_timer t1; |
931 | \& ev_timer t2; |
1387 | \& ev_timer t2; |
932 | \& } |
1388 | \& } |
933 | .Ve |
1389 | .Ve |
934 | .PP |
1390 | .PP |
935 | In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more complicated, |
1391 | In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more |
936 | you need to use \f(CW\*(C`offsetof\*(C'\fR: |
1392 | complicated: Either you store the address of your \f(CW\*(C`my_biggy\*(C'\fR struct |
|
|
1393 | in the \f(CW\*(C`data\*(C'\fR member of the watcher (for woozies), or you need to use |
|
|
1394 | some pointer arithmetic using \f(CW\*(C`offsetof\*(C'\fR inside your watchers (for real |
|
|
1395 | programmers): |
937 | .PP |
1396 | .PP |
938 | .Vb 1 |
1397 | .Vb 1 |
939 | \& #include <stddef.h> |
1398 | \& #include <stddef.h> |
940 | .Ve |
1399 | \& |
941 | .PP |
|
|
942 | .Vb 6 |
|
|
943 | \& static void |
1400 | \& static void |
944 | \& t1_cb (EV_P_ struct ev_timer *w, int revents) |
1401 | \& t1_cb (EV_P_ ev_timer *w, int revents) |
945 | \& { |
1402 | \& { |
946 | \& struct my_biggy big = (struct my_biggy * |
1403 | \& struct my_biggy big = (struct my_biggy *) |
947 | \& (((char *)w) - offsetof (struct my_biggy, t1)); |
1404 | \& (((char *)w) \- offsetof (struct my_biggy, t1)); |
948 | \& } |
1405 | \& } |
949 | .Ve |
1406 | \& |
950 | .PP |
|
|
951 | .Vb 6 |
|
|
952 | \& static void |
1407 | \& static void |
953 | \& t2_cb (EV_P_ struct ev_timer *w, int revents) |
1408 | \& t2_cb (EV_P_ ev_timer *w, int revents) |
954 | \& { |
1409 | \& { |
955 | \& struct my_biggy big = (struct my_biggy * |
1410 | \& struct my_biggy big = (struct my_biggy *) |
956 | \& (((char *)w) - offsetof (struct my_biggy, t2)); |
1411 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
957 | \& } |
1412 | \& } |
958 | .Ve |
1413 | .Ve |
|
|
1414 | .SS "\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0" |
|
|
1415 | .IX Subsection "WATCHER PRIORITY MODELS" |
|
|
1416 | Many event loops support \fIwatcher priorities\fR, which are usually small |
|
|
1417 | integers that influence the ordering of event callback invocation |
|
|
1418 | between watchers in some way, all else being equal. |
|
|
1419 | .PP |
|
|
1420 | In libev, Watcher priorities can be set using \f(CW\*(C`ev_set_priority\*(C'\fR. See its |
|
|
1421 | description for the more technical details such as the actual priority |
|
|
1422 | range. |
|
|
1423 | .PP |
|
|
1424 | There are two common ways how these these priorities are being interpreted |
|
|
1425 | by event loops: |
|
|
1426 | .PP |
|
|
1427 | In the more common lock-out model, higher priorities \*(L"lock out\*(R" invocation |
|
|
1428 | of lower priority watchers, which means as long as higher priority |
|
|
1429 | watchers receive events, lower priority watchers are not being invoked. |
|
|
1430 | .PP |
|
|
1431 | The less common only-for-ordering model uses priorities solely to order |
|
|
1432 | callback invocation within a single event loop iteration: Higher priority |
|
|
1433 | watchers are invoked before lower priority ones, but they all get invoked |
|
|
1434 | before polling for new events. |
|
|
1435 | .PP |
|
|
1436 | Libev uses the second (only-for-ordering) model for all its watchers |
|
|
1437 | except for idle watchers (which use the lock-out model). |
|
|
1438 | .PP |
|
|
1439 | The rationale behind this is that implementing the lock-out model for |
|
|
1440 | watchers is not well supported by most kernel interfaces, and most event |
|
|
1441 | libraries will just poll for the same events again and again as long as |
|
|
1442 | their callbacks have not been executed, which is very inefficient in the |
|
|
1443 | common case of one high-priority watcher locking out a mass of lower |
|
|
1444 | priority ones. |
|
|
1445 | .PP |
|
|
1446 | Static (ordering) priorities are most useful when you have two or more |
|
|
1447 | watchers handling the same resource: a typical usage example is having an |
|
|
1448 | \&\f(CW\*(C`ev_io\*(C'\fR watcher to receive data, and an associated \f(CW\*(C`ev_timer\*(C'\fR to handle |
|
|
1449 | timeouts. Under load, data might be received while the program handles |
|
|
1450 | other jobs, but since timers normally get invoked first, the timeout |
|
|
1451 | handler will be executed before checking for data. In that case, giving |
|
|
1452 | the timer a lower priority than the I/O watcher ensures that I/O will be |
|
|
1453 | handled first even under adverse conditions (which is usually, but not |
|
|
1454 | always, what you want). |
|
|
1455 | .PP |
|
|
1456 | Since idle watchers use the \*(L"lock-out\*(R" model, meaning that idle watchers |
|
|
1457 | will only be executed when no same or higher priority watchers have |
|
|
1458 | received events, they can be used to implement the \*(L"lock-out\*(R" model when |
|
|
1459 | required. |
|
|
1460 | .PP |
|
|
1461 | For example, to emulate how many other event libraries handle priorities, |
|
|
1462 | you can associate an \f(CW\*(C`ev_idle\*(C'\fR watcher to each such watcher, and in |
|
|
1463 | the normal watcher callback, you just start the idle watcher. The real |
|
|
1464 | processing is done in the idle watcher callback. This causes libev to |
|
|
1465 | continously poll and process kernel event data for the watcher, but when |
|
|
1466 | the lock-out case is known to be rare (which in turn is rare :), this is |
|
|
1467 | workable. |
|
|
1468 | .PP |
|
|
1469 | Usually, however, the lock-out model implemented that way will perform |
|
|
1470 | miserably under the type of load it was designed to handle. In that case, |
|
|
1471 | it might be preferable to stop the real watcher before starting the |
|
|
1472 | idle watcher, so the kernel will not have to process the event in case |
|
|
1473 | the actual processing will be delayed for considerable time. |
|
|
1474 | .PP |
|
|
1475 | Here is an example of an I/O watcher that should run at a strictly lower |
|
|
1476 | priority than the default, and which should only process data when no |
|
|
1477 | other events are pending: |
|
|
1478 | .PP |
|
|
1479 | .Vb 2 |
|
|
1480 | \& ev_idle idle; // actual processing watcher |
|
|
1481 | \& ev_io io; // actual event watcher |
|
|
1482 | \& |
|
|
1483 | \& static void |
|
|
1484 | \& io_cb (EV_P_ ev_io *w, int revents) |
|
|
1485 | \& { |
|
|
1486 | \& // stop the I/O watcher, we received the event, but |
|
|
1487 | \& // are not yet ready to handle it. |
|
|
1488 | \& ev_io_stop (EV_A_ w); |
|
|
1489 | \& |
|
|
1490 | \& // start the idle watcher to ahndle the actual event. |
|
|
1491 | \& // it will not be executed as long as other watchers |
|
|
1492 | \& // with the default priority are receiving events. |
|
|
1493 | \& ev_idle_start (EV_A_ &idle); |
|
|
1494 | \& } |
|
|
1495 | \& |
|
|
1496 | \& static void |
|
|
1497 | \& idle_cb (EV_P_ ev_idle *w, int revents) |
|
|
1498 | \& { |
|
|
1499 | \& // actual processing |
|
|
1500 | \& read (STDIN_FILENO, ...); |
|
|
1501 | \& |
|
|
1502 | \& // have to start the I/O watcher again, as |
|
|
1503 | \& // we have handled the event |
|
|
1504 | \& ev_io_start (EV_P_ &io); |
|
|
1505 | \& } |
|
|
1506 | \& |
|
|
1507 | \& // initialisation |
|
|
1508 | \& ev_idle_init (&idle, idle_cb); |
|
|
1509 | \& ev_io_init (&io, io_cb, STDIN_FILENO, EV_READ); |
|
|
1510 | \& ev_io_start (EV_DEFAULT_ &io); |
|
|
1511 | .Ve |
|
|
1512 | .PP |
|
|
1513 | In the \*(L"real\*(R" world, it might also be beneficial to start a timer, so that |
|
|
1514 | low-priority connections can not be locked out forever under load. This |
|
|
1515 | enables your program to keep a lower latency for important connections |
|
|
1516 | during short periods of high load, while not completely locking out less |
|
|
1517 | important ones. |
959 | .SH "WATCHER TYPES" |
1518 | .SH "WATCHER TYPES" |
960 | .IX Header "WATCHER TYPES" |
1519 | .IX Header "WATCHER TYPES" |
961 | This section describes each watcher in detail, but will not repeat |
1520 | This section describes each watcher in detail, but will not repeat |
962 | information given in the last section. Any initialisation/set macros, |
1521 | information given in the last section. Any initialisation/set macros, |
963 | functions and members specific to the watcher type are explained. |
1522 | functions and members specific to the watcher type are explained. |
… | |
… | |
968 | watcher is stopped to your hearts content), or \fI[read\-write]\fR, which |
1527 | watcher is stopped to your hearts content), or \fI[read\-write]\fR, which |
969 | means you can expect it to have some sensible content while the watcher |
1528 | means you can expect it to have some sensible content while the watcher |
970 | is active, but you can also modify it. Modifying it may not do something |
1529 | is active, but you can also modify it. Modifying it may not do something |
971 | sensible or take immediate effect (or do anything at all), but libev will |
1530 | sensible or take immediate effect (or do anything at all), but libev will |
972 | not crash or malfunction in any way. |
1531 | not crash or malfunction in any way. |
973 | .ie n .Sh """ev_io"" \- is this file descriptor readable or writable?" |
1532 | .ie n .SS """ev_io"" \- is this file descriptor readable or writable?" |
974 | .el .Sh "\f(CWev_io\fP \- is this file descriptor readable or writable?" |
1533 | .el .SS "\f(CWev_io\fP \- is this file descriptor readable or writable?" |
975 | .IX Subsection "ev_io - is this file descriptor readable or writable?" |
1534 | .IX Subsection "ev_io - is this file descriptor readable or writable?" |
976 | I/O watchers check whether a file descriptor is readable or writable |
1535 | I/O watchers check whether a file descriptor is readable or writable |
977 | in each iteration of the event loop, or, more precisely, when reading |
1536 | in each iteration of the event loop, or, more precisely, when reading |
978 | would not block the process and writing would at least be able to write |
1537 | would not block the process and writing would at least be able to write |
979 | some data. This behaviour is called level-triggering because you keep |
1538 | some data. This behaviour is called level-triggering because you keep |
… | |
… | |
984 | In general you can register as many read and/or write event watchers per |
1543 | In general you can register as many read and/or write event watchers per |
985 | fd as you want (as long as you don't confuse yourself). Setting all file |
1544 | fd as you want (as long as you don't confuse yourself). Setting all file |
986 | descriptors to non-blocking mode is also usually a good idea (but not |
1545 | descriptors to non-blocking mode is also usually a good idea (but not |
987 | required if you know what you are doing). |
1546 | required if you know what you are doing). |
988 | .PP |
1547 | .PP |
989 | You have to be careful with dup'ed file descriptors, though. Some backends |
1548 | If you cannot use non-blocking mode, then force the use of a |
990 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
1549 | known-to-be-good backend (at the time of this writing, this includes only |
991 | descriptors correctly if you register interest in two or more fds pointing |
1550 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and \f(CW\*(C`EVBACKEND_POLL\*(C'\fR). The same applies to file |
992 | to the same underlying file/socket/etc. description (that is, they share |
1551 | descriptors for which non-blocking operation makes no sense (such as |
993 | the same underlying \*(L"file open\*(R"). |
1552 | files) \- libev doesn't guarentee any specific behaviour in that case. |
994 | .PP |
|
|
995 | If you must do this, then force the use of a known-to-be-good backend |
|
|
996 | (at the time of this writing, this includes only \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and |
|
|
997 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR). |
|
|
998 | .PP |
1553 | .PP |
999 | Another thing you have to watch out for is that it is quite easy to |
1554 | Another thing you have to watch out for is that it is quite easy to |
1000 | receive \*(L"spurious\*(R" readyness notifications, that is your callback might |
1555 | receive \*(L"spurious\*(R" readiness notifications, that is your callback might |
1001 | be called with \f(CW\*(C`EV_READ\*(C'\fR but a subsequent \f(CW\*(C`read\*(C'\fR(2) will actually block |
1556 | be called with \f(CW\*(C`EV_READ\*(C'\fR but a subsequent \f(CW\*(C`read\*(C'\fR(2) will actually block |
1002 | because there is no data. Not only are some backends known to create a |
1557 | because there is no data. Not only are some backends known to create a |
1003 | lot of those (for example solaris ports), it is very easy to get into |
1558 | lot of those (for example Solaris ports), it is very easy to get into |
1004 | this situation even with a relatively standard program structure. Thus |
1559 | this situation even with a relatively standard program structure. Thus |
1005 | it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning |
1560 | it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning |
1006 | \&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives. |
1561 | \&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives. |
1007 | .PP |
1562 | .PP |
1008 | If you cannot run the fd in non-blocking mode (for example you should not |
1563 | If you cannot run the fd in non-blocking mode (for example you should |
1009 | play around with an Xlib connection), then you have to seperately re-test |
1564 | not play around with an Xlib connection), then you have to separately |
1010 | wether a file descriptor is really ready with a known-to-be good interface |
1565 | re-test whether a file descriptor is really ready with a known-to-be good |
1011 | such as poll (fortunately in our Xlib example, Xlib already does this on |
1566 | interface such as poll (fortunately in our Xlib example, Xlib already |
1012 | its own, so its quite safe to use). |
1567 | does this on its own, so its quite safe to use). Some people additionally |
|
|
1568 | use \f(CW\*(C`SIGALRM\*(C'\fR and an interval timer, just to be sure you won't block |
|
|
1569 | indefinitely. |
|
|
1570 | .PP |
|
|
1571 | But really, best use non-blocking mode. |
|
|
1572 | .PP |
|
|
1573 | \fIThe special problem of disappearing file descriptors\fR |
|
|
1574 | .IX Subsection "The special problem of disappearing file descriptors" |
|
|
1575 | .PP |
|
|
1576 | Some backends (e.g. kqueue, epoll) need to be told about closing a file |
|
|
1577 | descriptor (either due to calling \f(CW\*(C`close\*(C'\fR explicitly or any other means, |
|
|
1578 | such as \f(CW\*(C`dup2\*(C'\fR). The reason is that you register interest in some file |
|
|
1579 | descriptor, but when it goes away, the operating system will silently drop |
|
|
1580 | this interest. If another file descriptor with the same number then is |
|
|
1581 | registered with libev, there is no efficient way to see that this is, in |
|
|
1582 | fact, a different file descriptor. |
|
|
1583 | .PP |
|
|
1584 | To avoid having to explicitly tell libev about such cases, libev follows |
|
|
1585 | the following policy: Each time \f(CW\*(C`ev_io_set\*(C'\fR is being called, libev |
|
|
1586 | will assume that this is potentially a new file descriptor, otherwise |
|
|
1587 | it is assumed that the file descriptor stays the same. That means that |
|
|
1588 | you \fIhave\fR to call \f(CW\*(C`ev_io_set\*(C'\fR (or \f(CW\*(C`ev_io_init\*(C'\fR) when you change the |
|
|
1589 | descriptor even if the file descriptor number itself did not change. |
|
|
1590 | .PP |
|
|
1591 | This is how one would do it normally anyway, the important point is that |
|
|
1592 | the libev application should not optimise around libev but should leave |
|
|
1593 | optimisations to libev. |
|
|
1594 | .PP |
|
|
1595 | \fIThe special problem of dup'ed file descriptors\fR |
|
|
1596 | .IX Subsection "The special problem of dup'ed file descriptors" |
|
|
1597 | .PP |
|
|
1598 | Some backends (e.g. epoll), cannot register events for file descriptors, |
|
|
1599 | but only events for the underlying file descriptions. That means when you |
|
|
1600 | have \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors or weirder constellations, and register |
|
|
1601 | events for them, only one file descriptor might actually receive events. |
|
|
1602 | .PP |
|
|
1603 | There is no workaround possible except not registering events |
|
|
1604 | for potentially \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors, or to resort to |
|
|
1605 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
|
|
1606 | .PP |
|
|
1607 | \fIThe special problem of fork\fR |
|
|
1608 | .IX Subsection "The special problem of fork" |
|
|
1609 | .PP |
|
|
1610 | Some backends (epoll, kqueue) do not support \f(CW\*(C`fork ()\*(C'\fR at all or exhibit |
|
|
1611 | useless behaviour. Libev fully supports fork, but needs to be told about |
|
|
1612 | it in the child. |
|
|
1613 | .PP |
|
|
1614 | To support fork in your programs, you either have to call |
|
|
1615 | \&\f(CW\*(C`ev_default_fork ()\*(C'\fR or \f(CW\*(C`ev_loop_fork ()\*(C'\fR after a fork in the child, |
|
|
1616 | enable \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR, or resort to \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or |
|
|
1617 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
|
|
1618 | .PP |
|
|
1619 | \fIThe special problem of \s-1SIGPIPE\s0\fR |
|
|
1620 | .IX Subsection "The special problem of SIGPIPE" |
|
|
1621 | .PP |
|
|
1622 | While not really specific to libev, it is easy to forget about \f(CW\*(C`SIGPIPE\*(C'\fR: |
|
|
1623 | when writing to a pipe whose other end has been closed, your program gets |
|
|
1624 | sent a \s-1SIGPIPE\s0, which, by default, aborts your program. For most programs |
|
|
1625 | this is sensible behaviour, for daemons, this is usually undesirable. |
|
|
1626 | .PP |
|
|
1627 | So when you encounter spurious, unexplained daemon exits, make sure you |
|
|
1628 | ignore \s-1SIGPIPE\s0 (and maybe make sure you log the exit status of your daemon |
|
|
1629 | somewhere, as that would have given you a big clue). |
|
|
1630 | .PP |
|
|
1631 | \fIWatcher-Specific Functions\fR |
|
|
1632 | .IX Subsection "Watcher-Specific Functions" |
1013 | .IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 |
1633 | .IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 |
1014 | .IX Item "ev_io_init (ev_io *, callback, int fd, int events)" |
1634 | .IX Item "ev_io_init (ev_io *, callback, int fd, int events)" |
1015 | .PD 0 |
1635 | .PD 0 |
1016 | .IP "ev_io_set (ev_io *, int fd, int events)" 4 |
1636 | .IP "ev_io_set (ev_io *, int fd, int events)" 4 |
1017 | .IX Item "ev_io_set (ev_io *, int fd, int events)" |
1637 | .IX Item "ev_io_set (ev_io *, int fd, int events)" |
1018 | .PD |
1638 | .PD |
1019 | Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The \f(CW\*(C`fd\*(C'\fR is the file descriptor to |
1639 | Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The \f(CW\*(C`fd\*(C'\fR is the file descriptor to |
1020 | rceeive events for and events is either \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or |
1640 | receive events for and \f(CW\*(C`events\*(C'\fR is either \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or |
1021 | \&\f(CW\*(C`EV_READ | EV_WRITE\*(C'\fR to receive the given events. |
1641 | \&\f(CW\*(C`EV_READ | EV_WRITE\*(C'\fR, to express the desire to receive the given events. |
1022 | .IP "int fd [read\-only]" 4 |
1642 | .IP "int fd [read\-only]" 4 |
1023 | .IX Item "int fd [read-only]" |
1643 | .IX Item "int fd [read-only]" |
1024 | The file descriptor being watched. |
1644 | The file descriptor being watched. |
1025 | .IP "int events [read\-only]" 4 |
1645 | .IP "int events [read\-only]" 4 |
1026 | .IX Item "int events [read-only]" |
1646 | .IX Item "int events [read-only]" |
1027 | The events being watched. |
1647 | The events being watched. |
1028 | .PP |
1648 | .PP |
|
|
1649 | \fIExamples\fR |
|
|
1650 | .IX Subsection "Examples" |
|
|
1651 | .PP |
1029 | Example: Call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well |
1652 | Example: Call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well |
1030 | readable, but only once. Since it is likely line\-buffered, you could |
1653 | readable, but only once. Since it is likely line-buffered, you could |
1031 | attempt to read a whole line in the callback. |
1654 | attempt to read a whole line in the callback. |
1032 | .PP |
1655 | .PP |
1033 | .Vb 6 |
1656 | .Vb 6 |
1034 | \& static void |
1657 | \& static void |
1035 | \& stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1658 | \& stdin_readable_cb (struct ev_loop *loop, ev_io *w, int revents) |
1036 | \& { |
1659 | \& { |
1037 | \& ev_io_stop (loop, w); |
1660 | \& ev_io_stop (loop, w); |
1038 | \& .. read from stdin here (or from w->fd) and haqndle any I/O errors |
1661 | \& .. read from stdin here (or from w\->fd) and handle any I/O errors |
1039 | \& } |
1662 | \& } |
1040 | .Ve |
1663 | \& |
1041 | .PP |
|
|
1042 | .Vb 6 |
|
|
1043 | \& ... |
1664 | \& ... |
1044 | \& struct ev_loop *loop = ev_default_init (0); |
1665 | \& struct ev_loop *loop = ev_default_init (0); |
1045 | \& struct ev_io stdin_readable; |
1666 | \& ev_io stdin_readable; |
1046 | \& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1667 | \& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1047 | \& ev_io_start (loop, &stdin_readable); |
1668 | \& ev_io_start (loop, &stdin_readable); |
1048 | \& ev_loop (loop, 0); |
1669 | \& ev_loop (loop, 0); |
1049 | .Ve |
1670 | .Ve |
1050 | .ie n .Sh """ev_timer"" \- relative and optionally repeating timeouts" |
1671 | .ie n .SS """ev_timer"" \- relative and optionally repeating timeouts" |
1051 | .el .Sh "\f(CWev_timer\fP \- relative and optionally repeating timeouts" |
1672 | .el .SS "\f(CWev_timer\fP \- relative and optionally repeating timeouts" |
1052 | .IX Subsection "ev_timer - relative and optionally repeating timeouts" |
1673 | .IX Subsection "ev_timer - relative and optionally repeating timeouts" |
1053 | Timer watchers are simple relative timers that generate an event after a |
1674 | Timer watchers are simple relative timers that generate an event after a |
1054 | given time, and optionally repeating in regular intervals after that. |
1675 | given time, and optionally repeating in regular intervals after that. |
1055 | .PP |
1676 | .PP |
1056 | The timers are based on real time, that is, if you register an event that |
1677 | The timers are based on real time, that is, if you register an event that |
1057 | times out after an hour and you reset your system clock to last years |
1678 | times out after an hour and you reset your system clock to January last |
1058 | time, it will still time out after (roughly) and hour. \*(L"Roughly\*(R" because |
1679 | year, it will still time out after (roughly) one hour. \*(L"Roughly\*(R" because |
1059 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1680 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1060 | monotonic clock option helps a lot here). |
1681 | monotonic clock option helps a lot here). |
|
|
1682 | .PP |
|
|
1683 | The callback is guaranteed to be invoked only \fIafter\fR its timeout has |
|
|
1684 | passed (not \fIat\fR, so on systems with very low-resolution clocks this |
|
|
1685 | might introduce a small delay). If multiple timers become ready during the |
|
|
1686 | same loop iteration then the ones with earlier time-out values are invoked |
|
|
1687 | before ones of the same priority with later time-out values (but this is |
|
|
1688 | no longer true when a callback calls \f(CW\*(C`ev_loop\*(C'\fR recursively). |
|
|
1689 | .PP |
|
|
1690 | \fIBe smart about timeouts\fR |
|
|
1691 | .IX Subsection "Be smart about timeouts" |
|
|
1692 | .PP |
|
|
1693 | Many real-world problems involve some kind of timeout, usually for error |
|
|
1694 | recovery. A typical example is an \s-1HTTP\s0 request \- if the other side hangs, |
|
|
1695 | you want to raise some error after a while. |
|
|
1696 | .PP |
|
|
1697 | What follows are some ways to handle this problem, from obvious and |
|
|
1698 | inefficient to smart and efficient. |
|
|
1699 | .PP |
|
|
1700 | In the following, a 60 second activity timeout is assumed \- a timeout that |
|
|
1701 | gets reset to 60 seconds each time there is activity (e.g. each time some |
|
|
1702 | data or other life sign was received). |
|
|
1703 | .IP "1. Use a timer and stop, reinitialise and start it on activity." 4 |
|
|
1704 | .IX Item "1. Use a timer and stop, reinitialise and start it on activity." |
|
|
1705 | This is the most obvious, but not the most simple way: In the beginning, |
|
|
1706 | start the watcher: |
|
|
1707 | .Sp |
|
|
1708 | .Vb 2 |
|
|
1709 | \& ev_timer_init (timer, callback, 60., 0.); |
|
|
1710 | \& ev_timer_start (loop, timer); |
|
|
1711 | .Ve |
|
|
1712 | .Sp |
|
|
1713 | Then, each time there is some activity, \f(CW\*(C`ev_timer_stop\*(C'\fR it, initialise it |
|
|
1714 | and start it again: |
|
|
1715 | .Sp |
|
|
1716 | .Vb 3 |
|
|
1717 | \& ev_timer_stop (loop, timer); |
|
|
1718 | \& ev_timer_set (timer, 60., 0.); |
|
|
1719 | \& ev_timer_start (loop, timer); |
|
|
1720 | .Ve |
|
|
1721 | .Sp |
|
|
1722 | This is relatively simple to implement, but means that each time there is |
|
|
1723 | some activity, libev will first have to remove the timer from its internal |
|
|
1724 | data structure and then add it again. Libev tries to be fast, but it's |
|
|
1725 | still not a constant-time operation. |
|
|
1726 | .ie n .IP "2. Use a timer and re-start it with ""ev_timer_again"" inactivity." 4 |
|
|
1727 | .el .IP "2. Use a timer and re-start it with \f(CWev_timer_again\fR inactivity." 4 |
|
|
1728 | .IX Item "2. Use a timer and re-start it with ev_timer_again inactivity." |
|
|
1729 | This is the easiest way, and involves using \f(CW\*(C`ev_timer_again\*(C'\fR instead of |
|
|
1730 | \&\f(CW\*(C`ev_timer_start\*(C'\fR. |
|
|
1731 | .Sp |
|
|
1732 | To implement this, configure an \f(CW\*(C`ev_timer\*(C'\fR with a \f(CW\*(C`repeat\*(C'\fR value |
|
|
1733 | of \f(CW60\fR and then call \f(CW\*(C`ev_timer_again\*(C'\fR at start and each time you |
|
|
1734 | successfully read or write some data. If you go into an idle state where |
|
|
1735 | you do not expect data to travel on the socket, you can \f(CW\*(C`ev_timer_stop\*(C'\fR |
|
|
1736 | the timer, and \f(CW\*(C`ev_timer_again\*(C'\fR will automatically restart it if need be. |
|
|
1737 | .Sp |
|
|
1738 | That means you can ignore both the \f(CW\*(C`ev_timer_start\*(C'\fR function and the |
|
|
1739 | \&\f(CW\*(C`after\*(C'\fR argument to \f(CW\*(C`ev_timer_set\*(C'\fR, and only ever use the \f(CW\*(C`repeat\*(C'\fR |
|
|
1740 | member and \f(CW\*(C`ev_timer_again\*(C'\fR. |
|
|
1741 | .Sp |
|
|
1742 | At start: |
|
|
1743 | .Sp |
|
|
1744 | .Vb 3 |
|
|
1745 | \& ev_init (timer, callback); |
|
|
1746 | \& timer\->repeat = 60.; |
|
|
1747 | \& ev_timer_again (loop, timer); |
|
|
1748 | .Ve |
|
|
1749 | .Sp |
|
|
1750 | Each time there is some activity: |
|
|
1751 | .Sp |
|
|
1752 | .Vb 1 |
|
|
1753 | \& ev_timer_again (loop, timer); |
|
|
1754 | .Ve |
|
|
1755 | .Sp |
|
|
1756 | It is even possible to change the time-out on the fly, regardless of |
|
|
1757 | whether the watcher is active or not: |
|
|
1758 | .Sp |
|
|
1759 | .Vb 2 |
|
|
1760 | \& timer\->repeat = 30.; |
|
|
1761 | \& ev_timer_again (loop, timer); |
|
|
1762 | .Ve |
|
|
1763 | .Sp |
|
|
1764 | This is slightly more efficient then stopping/starting the timer each time |
|
|
1765 | you want to modify its timeout value, as libev does not have to completely |
|
|
1766 | remove and re-insert the timer from/into its internal data structure. |
|
|
1767 | .Sp |
|
|
1768 | It is, however, even simpler than the \*(L"obvious\*(R" way to do it. |
|
|
1769 | .IP "3. Let the timer time out, but then re-arm it as required." 4 |
|
|
1770 | .IX Item "3. Let the timer time out, but then re-arm it as required." |
|
|
1771 | This method is more tricky, but usually most efficient: Most timeouts are |
|
|
1772 | relatively long compared to the intervals between other activity \- in |
|
|
1773 | our example, within 60 seconds, there are usually many I/O events with |
|
|
1774 | associated activity resets. |
|
|
1775 | .Sp |
|
|
1776 | In this case, it would be more efficient to leave the \f(CW\*(C`ev_timer\*(C'\fR alone, |
|
|
1777 | but remember the time of last activity, and check for a real timeout only |
|
|
1778 | within the callback: |
|
|
1779 | .Sp |
|
|
1780 | .Vb 1 |
|
|
1781 | \& ev_tstamp last_activity; // time of last activity |
|
|
1782 | \& |
|
|
1783 | \& static void |
|
|
1784 | \& callback (EV_P_ ev_timer *w, int revents) |
|
|
1785 | \& { |
|
|
1786 | \& ev_tstamp now = ev_now (EV_A); |
|
|
1787 | \& ev_tstamp timeout = last_activity + 60.; |
|
|
1788 | \& |
|
|
1789 | \& // if last_activity + 60. is older than now, we did time out |
|
|
1790 | \& if (timeout < now) |
|
|
1791 | \& { |
|
|
1792 | \& // timeout occured, take action |
|
|
1793 | \& } |
|
|
1794 | \& else |
|
|
1795 | \& { |
|
|
1796 | \& // callback was invoked, but there was some activity, re\-arm |
|
|
1797 | \& // the watcher to fire in last_activity + 60, which is |
|
|
1798 | \& // guaranteed to be in the future, so "again" is positive: |
|
|
1799 | \& w\->repeat = timeout \- now; |
|
|
1800 | \& ev_timer_again (EV_A_ w); |
|
|
1801 | \& } |
|
|
1802 | \& } |
|
|
1803 | .Ve |
|
|
1804 | .Sp |
|
|
1805 | To summarise the callback: first calculate the real timeout (defined |
|
|
1806 | as \*(L"60 seconds after the last activity\*(R"), then check if that time has |
|
|
1807 | been reached, which means something \fIdid\fR, in fact, time out. Otherwise |
|
|
1808 | the callback was invoked too early (\f(CW\*(C`timeout\*(C'\fR is in the future), so |
|
|
1809 | re-schedule the timer to fire at that future time, to see if maybe we have |
|
|
1810 | a timeout then. |
|
|
1811 | .Sp |
|
|
1812 | Note how \f(CW\*(C`ev_timer_again\*(C'\fR is used, taking advantage of the |
|
|
1813 | \&\f(CW\*(C`ev_timer_again\*(C'\fR optimisation when the timer is already running. |
|
|
1814 | .Sp |
|
|
1815 | This scheme causes more callback invocations (about one every 60 seconds |
|
|
1816 | minus half the average time between activity), but virtually no calls to |
|
|
1817 | libev to change the timeout. |
|
|
1818 | .Sp |
|
|
1819 | To start the timer, simply initialise the watcher and set \f(CW\*(C`last_activity\*(C'\fR |
|
|
1820 | to the current time (meaning we just have some activity :), then call the |
|
|
1821 | callback, which will \*(L"do the right thing\*(R" and start the timer: |
|
|
1822 | .Sp |
|
|
1823 | .Vb 3 |
|
|
1824 | \& ev_init (timer, callback); |
|
|
1825 | \& last_activity = ev_now (loop); |
|
|
1826 | \& callback (loop, timer, EV_TIMEOUT); |
|
|
1827 | .Ve |
|
|
1828 | .Sp |
|
|
1829 | And when there is some activity, simply store the current time in |
|
|
1830 | \&\f(CW\*(C`last_activity\*(C'\fR, no libev calls at all: |
|
|
1831 | .Sp |
|
|
1832 | .Vb 1 |
|
|
1833 | \& last_actiivty = ev_now (loop); |
|
|
1834 | .Ve |
|
|
1835 | .Sp |
|
|
1836 | This technique is slightly more complex, but in most cases where the |
|
|
1837 | time-out is unlikely to be triggered, much more efficient. |
|
|
1838 | .Sp |
|
|
1839 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
|
|
1840 | callback :) \- just change the timeout and invoke the callback, which will |
|
|
1841 | fix things for you. |
|
|
1842 | .IP "4. Wee, just use a double-linked list for your timeouts." 4 |
|
|
1843 | .IX Item "4. Wee, just use a double-linked list for your timeouts." |
|
|
1844 | If there is not one request, but many thousands (millions...), all |
|
|
1845 | employing some kind of timeout with the same timeout value, then one can |
|
|
1846 | do even better: |
|
|
1847 | .Sp |
|
|
1848 | When starting the timeout, calculate the timeout value and put the timeout |
|
|
1849 | at the \fIend\fR of the list. |
|
|
1850 | .Sp |
|
|
1851 | Then use an \f(CW\*(C`ev_timer\*(C'\fR to fire when the timeout at the \fIbeginning\fR of |
|
|
1852 | the list is expected to fire (for example, using the technique #3). |
|
|
1853 | .Sp |
|
|
1854 | When there is some activity, remove the timer from the list, recalculate |
|
|
1855 | the timeout, append it to the end of the list again, and make sure to |
|
|
1856 | update the \f(CW\*(C`ev_timer\*(C'\fR if it was taken from the beginning of the list. |
|
|
1857 | .Sp |
|
|
1858 | This way, one can manage an unlimited number of timeouts in O(1) time for |
|
|
1859 | starting, stopping and updating the timers, at the expense of a major |
|
|
1860 | complication, and having to use a constant timeout. The constant timeout |
|
|
1861 | ensures that the list stays sorted. |
|
|
1862 | .PP |
|
|
1863 | So which method the best? |
|
|
1864 | .PP |
|
|
1865 | Method #2 is a simple no-brain-required solution that is adequate in most |
|
|
1866 | situations. Method #3 requires a bit more thinking, but handles many cases |
|
|
1867 | better, and isn't very complicated either. In most case, choosing either |
|
|
1868 | one is fine, with #3 being better in typical situations. |
|
|
1869 | .PP |
|
|
1870 | Method #1 is almost always a bad idea, and buys you nothing. Method #4 is |
|
|
1871 | rather complicated, but extremely efficient, something that really pays |
|
|
1872 | off after the first million or so of active timers, i.e. it's usually |
|
|
1873 | overkill :) |
|
|
1874 | .PP |
|
|
1875 | \fIThe special problem of time updates\fR |
|
|
1876 | .IX Subsection "The special problem of time updates" |
|
|
1877 | .PP |
|
|
1878 | Establishing the current time is a costly operation (it usually takes at |
|
|
1879 | least two system calls): \s-1EV\s0 therefore updates its idea of the current |
|
|
1880 | time only before and after \f(CW\*(C`ev_loop\*(C'\fR collects new events, which causes a |
|
|
1881 | growing difference between \f(CW\*(C`ev_now ()\*(C'\fR and \f(CW\*(C`ev_time ()\*(C'\fR when handling |
|
|
1882 | lots of events in one iteration. |
1061 | .PP |
1883 | .PP |
1062 | The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR |
1884 | The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR |
1063 | time. This is usually the right thing as this timestamp refers to the time |
1885 | time. This is usually the right thing as this timestamp refers to the time |
1064 | of the event triggering whatever timeout you are modifying/starting. If |
1886 | of the event triggering whatever timeout you are modifying/starting. If |
1065 | you suspect event processing to be delayed and you \fIneed\fR to base the timeout |
1887 | you suspect event processing to be delayed and you \fIneed\fR to base the |
1066 | on the current time, use something like this to adjust for this: |
1888 | timeout on the current time, use something like this to adjust for this: |
1067 | .PP |
1889 | .PP |
1068 | .Vb 1 |
1890 | .Vb 1 |
1069 | \& ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
1891 | \& ev_timer_set (&timer, after + ev_now () \- ev_time (), 0.); |
1070 | .Ve |
1892 | .Ve |
1071 | .PP |
1893 | .PP |
1072 | The callback is guarenteed to be invoked only when its timeout has passed, |
1894 | If the event loop is suspended for a long time, you can also force an |
1073 | but if multiple timers become ready during the same loop iteration then |
1895 | update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update |
1074 | order of execution is undefined. |
1896 | ()\*(C'\fR. |
|
|
1897 | .PP |
|
|
1898 | \fIThe special problems of suspended animation\fR |
|
|
1899 | .IX Subsection "The special problems of suspended animation" |
|
|
1900 | .PP |
|
|
1901 | When you leave the server world it is quite customary to hit machines that |
|
|
1902 | can suspend/hibernate \- what happens to the clocks during such a suspend? |
|
|
1903 | .PP |
|
|
1904 | Some quick tests made with a Linux 2.6.28 indicate that a suspend freezes |
|
|
1905 | all processes, while the clocks (\f(CW\*(C`times\*(C'\fR, \f(CW\*(C`CLOCK_MONOTONIC\*(C'\fR) continue |
|
|
1906 | to run until the system is suspended, but they will not advance while the |
|
|
1907 | system is suspended. That means, on resume, it will be as if the program |
|
|
1908 | was frozen for a few seconds, but the suspend time will not be counted |
|
|
1909 | towards \f(CW\*(C`ev_timer\*(C'\fR when a monotonic clock source is used. The real time |
|
|
1910 | clock advanced as expected, but if it is used as sole clocksource, then a |
|
|
1911 | long suspend would be detected as a time jump by libev, and timers would |
|
|
1912 | be adjusted accordingly. |
|
|
1913 | .PP |
|
|
1914 | I would not be surprised to see different behaviour in different between |
|
|
1915 | operating systems, \s-1OS\s0 versions or even different hardware. |
|
|
1916 | .PP |
|
|
1917 | The other form of suspend (job control, or sending a \s-1SIGSTOP\s0) will see a |
|
|
1918 | time jump in the monotonic clocks and the realtime clock. If the program |
|
|
1919 | is suspended for a very long time, and monotonic clock sources are in use, |
|
|
1920 | then you can expect \f(CW\*(C`ev_timer\*(C'\fRs to expire as the full suspension time |
|
|
1921 | will be counted towards the timers. When no monotonic clock source is in |
|
|
1922 | use, then libev will again assume a timejump and adjust accordingly. |
|
|
1923 | .PP |
|
|
1924 | It might be beneficial for this latter case to call \f(CW\*(C`ev_suspend\*(C'\fR |
|
|
1925 | and \f(CW\*(C`ev_resume\*(C'\fR in code that handles \f(CW\*(C`SIGTSTP\*(C'\fR, to at least get |
|
|
1926 | deterministic behaviour in this case (you can do nothing against |
|
|
1927 | \&\f(CW\*(C`SIGSTOP\*(C'\fR). |
|
|
1928 | .PP |
|
|
1929 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
1930 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1075 | .IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4 |
1931 | .IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4 |
1076 | .IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" |
1932 | .IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" |
1077 | .PD 0 |
1933 | .PD 0 |
1078 | .IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4 |
1934 | .IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4 |
1079 | .IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" |
1935 | .IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" |
1080 | .PD |
1936 | .PD |
1081 | Configure the timer to trigger after \f(CW\*(C`after\*(C'\fR seconds. If \f(CW\*(C`repeat\*(C'\fR is |
1937 | Configure the timer to trigger after \f(CW\*(C`after\*(C'\fR seconds. If \f(CW\*(C`repeat\*(C'\fR |
1082 | \&\f(CW0.\fR, then it will automatically be stopped. If it is positive, then the |
1938 | is \f(CW0.\fR, then it will automatically be stopped once the timeout is |
1083 | timer will automatically be configured to trigger again \f(CW\*(C`repeat\*(C'\fR seconds |
1939 | reached. If it is positive, then the timer will automatically be |
1084 | later, again, and again, until stopped manually. |
1940 | configured to trigger again \f(CW\*(C`repeat\*(C'\fR seconds later, again, and again, |
|
|
1941 | until stopped manually. |
1085 | .Sp |
1942 | .Sp |
1086 | The timer itself will do a best-effort at avoiding drift, that is, if you |
1943 | The timer itself will do a best-effort at avoiding drift, that is, if |
1087 | configure a timer to trigger every 10 seconds, then it will trigger at |
1944 | you configure a timer to trigger every 10 seconds, then it will normally |
1088 | exactly 10 second intervals. If, however, your program cannot keep up with |
1945 | trigger at exactly 10 second intervals. If, however, your program cannot |
1089 | the timer (because it takes longer than those 10 seconds to do stuff) the |
1946 | keep up with the timer (because it takes longer than those 10 seconds to |
1090 | timer will not fire more than once per event loop iteration. |
1947 | do stuff) the timer will not fire more than once per event loop iteration. |
1091 | .IP "ev_timer_again (loop)" 4 |
1948 | .IP "ev_timer_again (loop, ev_timer *)" 4 |
1092 | .IX Item "ev_timer_again (loop)" |
1949 | .IX Item "ev_timer_again (loop, ev_timer *)" |
1093 | This will act as if the timer timed out and restart it again if it is |
1950 | This will act as if the timer timed out and restart it again if it is |
1094 | repeating. The exact semantics are: |
1951 | repeating. The exact semantics are: |
1095 | .Sp |
1952 | .Sp |
1096 | If the timer is pending, its pending status is cleared. |
1953 | If the timer is pending, its pending status is cleared. |
1097 | .Sp |
1954 | .Sp |
1098 | If the timer is started but nonrepeating, stop it (as if it timed out). |
1955 | If the timer is started but non-repeating, stop it (as if it timed out). |
1099 | .Sp |
1956 | .Sp |
1100 | If the timer is repeating, either start it if necessary (with the |
1957 | If the timer is repeating, either start it if necessary (with the |
1101 | \&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value. |
1958 | \&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value. |
1102 | .Sp |
1959 | .Sp |
1103 | This sounds a bit complicated, but here is a useful and typical |
1960 | This sounds a bit complicated, see \*(L"Be smart about timeouts\*(R", above, for a |
1104 | example: Imagine you have a tcp connection and you want a so-called idle |
1961 | usage example. |
1105 | timeout, that is, you want to be called when there have been, say, 60 |
1962 | .IP "ev_timer_remaining (loop, ev_timer *)" 4 |
1106 | seconds of inactivity on the socket. The easiest way to do this is to |
1963 | .IX Item "ev_timer_remaining (loop, ev_timer *)" |
1107 | configure an \f(CW\*(C`ev_timer\*(C'\fR with a \f(CW\*(C`repeat\*(C'\fR value of \f(CW60\fR and then call |
1964 | Returns the remaining time until a timer fires. If the timer is active, |
1108 | \&\f(CW\*(C`ev_timer_again\*(C'\fR each time you successfully read or write some data. If |
1965 | then this time is relative to the current event loop time, otherwise it's |
1109 | you go into an idle state where you do not expect data to travel on the |
1966 | the timeout value currently configured. |
1110 | socket, you can \f(CW\*(C`ev_timer_stop\*(C'\fR the timer, and \f(CW\*(C`ev_timer_again\*(C'\fR will |
|
|
1111 | automatically restart it if need be. |
|
|
1112 | .Sp |
1967 | .Sp |
1113 | That means you can ignore the \f(CW\*(C`after\*(C'\fR value and \f(CW\*(C`ev_timer_start\*(C'\fR |
1968 | That is, after an \f(CW\*(C`ev_timer_set (w, 5, 7)\*(C'\fR, \f(CW\*(C`ev_timer_remaining\*(C'\fR returns |
1114 | altogether and only ever use the \f(CW\*(C`repeat\*(C'\fR value and \f(CW\*(C`ev_timer_again\*(C'\fR: |
1969 | \&\f(CW5\fR. When the timer is started and one second passes, \f(CW\*(C`ev_timer_remain\*(C'\fR |
1115 | .Sp |
1970 | will return \f(CW4\fR. When the timer expires and is restarted, it will return |
1116 | .Vb 8 |
1971 | roughly \f(CW7\fR (likely slightly less as callback invocation takes some time, |
1117 | \& ev_timer_init (timer, callback, 0., 5.); |
1972 | too), and so on. |
1118 | \& ev_timer_again (loop, timer); |
|
|
1119 | \& ... |
|
|
1120 | \& timer->again = 17.; |
|
|
1121 | \& ev_timer_again (loop, timer); |
|
|
1122 | \& ... |
|
|
1123 | \& timer->again = 10.; |
|
|
1124 | \& ev_timer_again (loop, timer); |
|
|
1125 | .Ve |
|
|
1126 | .Sp |
|
|
1127 | This is more slightly efficient then stopping/starting the timer each time |
|
|
1128 | you want to modify its timeout value. |
|
|
1129 | .IP "ev_tstamp repeat [read\-write]" 4 |
1973 | .IP "ev_tstamp repeat [read\-write]" 4 |
1130 | .IX Item "ev_tstamp repeat [read-write]" |
1974 | .IX Item "ev_tstamp repeat [read-write]" |
1131 | The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out |
1975 | The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out |
1132 | or \f(CW\*(C`ev_timer_again\*(C'\fR is called and determines the next timeout (if any), |
1976 | or \f(CW\*(C`ev_timer_again\*(C'\fR is called, and determines the next timeout (if any), |
1133 | which is also when any modifications are taken into account. |
1977 | which is also when any modifications are taken into account. |
1134 | .PP |
1978 | .PP |
|
|
1979 | \fIExamples\fR |
|
|
1980 | .IX Subsection "Examples" |
|
|
1981 | .PP |
1135 | Example: Create a timer that fires after 60 seconds. |
1982 | Example: Create a timer that fires after 60 seconds. |
1136 | .PP |
1983 | .PP |
1137 | .Vb 5 |
1984 | .Vb 5 |
1138 | \& static void |
1985 | \& static void |
1139 | \& one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1986 | \& one_minute_cb (struct ev_loop *loop, ev_timer *w, int revents) |
1140 | \& { |
1987 | \& { |
1141 | \& .. one minute over, w is actually stopped right here |
1988 | \& .. one minute over, w is actually stopped right here |
1142 | \& } |
1989 | \& } |
1143 | .Ve |
1990 | \& |
1144 | .PP |
|
|
1145 | .Vb 3 |
|
|
1146 | \& struct ev_timer mytimer; |
1991 | \& ev_timer mytimer; |
1147 | \& ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
1992 | \& ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
1148 | \& ev_timer_start (loop, &mytimer); |
1993 | \& ev_timer_start (loop, &mytimer); |
1149 | .Ve |
1994 | .Ve |
1150 | .PP |
1995 | .PP |
1151 | Example: Create a timeout timer that times out after 10 seconds of |
1996 | Example: Create a timeout timer that times out after 10 seconds of |
1152 | inactivity. |
1997 | inactivity. |
1153 | .PP |
1998 | .PP |
1154 | .Vb 5 |
1999 | .Vb 5 |
1155 | \& static void |
2000 | \& static void |
1156 | \& timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
2001 | \& timeout_cb (struct ev_loop *loop, ev_timer *w, int revents) |
1157 | \& { |
2002 | \& { |
1158 | \& .. ten seconds without any activity |
2003 | \& .. ten seconds without any activity |
1159 | \& } |
2004 | \& } |
1160 | .Ve |
2005 | \& |
1161 | .PP |
|
|
1162 | .Vb 4 |
|
|
1163 | \& struct ev_timer mytimer; |
2006 | \& ev_timer mytimer; |
1164 | \& ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
2007 | \& ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1165 | \& ev_timer_again (&mytimer); /* start timer */ |
2008 | \& ev_timer_again (&mytimer); /* start timer */ |
1166 | \& ev_loop (loop, 0); |
2009 | \& ev_loop (loop, 0); |
1167 | .Ve |
2010 | \& |
1168 | .PP |
|
|
1169 | .Vb 3 |
|
|
1170 | \& // and in some piece of code that gets executed on any "activity": |
2011 | \& // and in some piece of code that gets executed on any "activity": |
1171 | \& // reset the timeout to start ticking again at 10 seconds |
2012 | \& // reset the timeout to start ticking again at 10 seconds |
1172 | \& ev_timer_again (&mytimer); |
2013 | \& ev_timer_again (&mytimer); |
1173 | .Ve |
2014 | .Ve |
1174 | .ie n .Sh """ev_periodic"" \- to cron or not to cron?" |
2015 | .ie n .SS """ev_periodic"" \- to cron or not to cron?" |
1175 | .el .Sh "\f(CWev_periodic\fP \- to cron or not to cron?" |
2016 | .el .SS "\f(CWev_periodic\fP \- to cron or not to cron?" |
1176 | .IX Subsection "ev_periodic - to cron or not to cron?" |
2017 | .IX Subsection "ev_periodic - to cron or not to cron?" |
1177 | Periodic watchers are also timers of a kind, but they are very versatile |
2018 | Periodic watchers are also timers of a kind, but they are very versatile |
1178 | (and unfortunately a bit complex). |
2019 | (and unfortunately a bit complex). |
1179 | .PP |
2020 | .PP |
1180 | Unlike \f(CW\*(C`ev_timer\*(C'\fR's, they are not based on real time (or relative time) |
2021 | Unlike \f(CW\*(C`ev_timer\*(C'\fR, periodic watchers are not based on real time (or |
1181 | but on wallclock time (absolute time). You can tell a periodic watcher |
2022 | relative time, the physical time that passes) but on wall clock time |
1182 | to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a |
2023 | (absolute time, the thing you can read on your calender or clock). The |
1183 | periodic watcher to trigger in 10 seconds (by specifiying e.g. \f(CW\*(C`ev_now () |
2024 | difference is that wall clock time can run faster or slower than real |
1184 | + 10.\*(C'\fR) and then reset your system clock to the last year, then it will |
2025 | time, and time jumps are not uncommon (e.g. when you adjust your |
1185 | take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger |
2026 | wrist-watch). |
1186 | roughly 10 seconds later and of course not if you reset your system time |
|
|
1187 | again). |
|
|
1188 | .PP |
2027 | .PP |
1189 | They can also be used to implement vastly more complex timers, such as |
2028 | You can tell a periodic watcher to trigger after some specific point |
1190 | triggering an event on eahc midnight, local time. |
2029 | in time: for example, if you tell a periodic watcher to trigger \*(L"in 10 |
|
|
2030 | seconds\*(R" (by specifying e.g. \f(CW\*(C`ev_now () + 10.\*(C'\fR, that is, an absolute time |
|
|
2031 | not a delay) and then reset your system clock to January of the previous |
|
|
2032 | year, then it will take a year or more to trigger the event (unlike an |
|
|
2033 | \&\f(CW\*(C`ev_timer\*(C'\fR, which would still trigger roughly 10 seconds after starting |
|
|
2034 | it, as it uses a relative timeout). |
1191 | .PP |
2035 | .PP |
|
|
2036 | \&\f(CW\*(C`ev_periodic\*(C'\fR watchers can also be used to implement vastly more complex |
|
|
2037 | timers, such as triggering an event on each \*(L"midnight, local time\*(R", or |
|
|
2038 | other complicated rules. This cannot be done with \f(CW\*(C`ev_timer\*(C'\fR watchers, as |
|
|
2039 | those cannot react to time jumps. |
|
|
2040 | .PP |
1192 | As with timers, the callback is guarenteed to be invoked only when the |
2041 | As with timers, the callback is guaranteed to be invoked only when the |
1193 | time (\f(CW\*(C`at\*(C'\fR) has been passed, but if multiple periodic timers become ready |
2042 | point in time where it is supposed to trigger has passed. If multiple |
1194 | during the same loop iteration then order of execution is undefined. |
2043 | timers become ready during the same loop iteration then the ones with |
|
|
2044 | earlier time-out values are invoked before ones with later time-out values |
|
|
2045 | (but this is no longer true when a callback calls \f(CW\*(C`ev_loop\*(C'\fR recursively). |
|
|
2046 | .PP |
|
|
2047 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
2048 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1195 | .IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4 |
2049 | .IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp offset, ev_tstamp interval, reschedule_cb)" 4 |
1196 | .IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" |
2050 | .IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp offset, ev_tstamp interval, reschedule_cb)" |
1197 | .PD 0 |
2051 | .PD 0 |
1198 | .IP "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 4 |
2052 | .IP "ev_periodic_set (ev_periodic *, ev_tstamp offset, ev_tstamp interval, reschedule_cb)" 4 |
1199 | .IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" |
2053 | .IX Item "ev_periodic_set (ev_periodic *, ev_tstamp offset, ev_tstamp interval, reschedule_cb)" |
1200 | .PD |
2054 | .PD |
1201 | Lots of arguments, lets sort it out... There are basically three modes of |
2055 | Lots of arguments, let's sort it out... There are basically three modes of |
1202 | operation, and we will explain them from simplest to complex: |
2056 | operation, and we will explain them from simplest to most complex: |
1203 | .RS 4 |
2057 | .RS 4 |
1204 | .IP "* absolute timer (interval = reschedule_cb = 0)" 4 |
2058 | .IP "\(bu" 4 |
1205 | .IX Item "absolute timer (interval = reschedule_cb = 0)" |
2059 | absolute timer (offset = absolute time, interval = 0, reschedule_cb = 0) |
|
|
2060 | .Sp |
1206 | In this configuration the watcher triggers an event at the wallclock time |
2061 | In this configuration the watcher triggers an event after the wall clock |
1207 | \&\f(CW\*(C`at\*(C'\fR and doesn't repeat. It will not adjust when a time jump occurs, |
2062 | time \f(CW\*(C`offset\*(C'\fR has passed. It will not repeat and will not adjust when a |
1208 | that is, if it is to be run at January 1st 2011 then it will run when the |
2063 | time jump occurs, that is, if it is to be run at January 1st 2011 then it |
1209 | system time reaches or surpasses this time. |
2064 | will be stopped and invoked when the system clock reaches or surpasses |
1210 | .IP "* non-repeating interval timer (interval > 0, reschedule_cb = 0)" 4 |
2065 | this point in time. |
1211 | .IX Item "non-repeating interval timer (interval > 0, reschedule_cb = 0)" |
2066 | .IP "\(bu" 4 |
|
|
2067 | repeating interval timer (offset = offset within interval, interval > 0, reschedule_cb = 0) |
|
|
2068 | .Sp |
1212 | In this mode the watcher will always be scheduled to time out at the next |
2069 | In this mode the watcher will always be scheduled to time out at the next |
1213 | \&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N) and then repeat, regardless |
2070 | \&\f(CW\*(C`offset + N * interval\*(C'\fR time (for some integer N, which can also be |
1214 | of any time jumps. |
2071 | negative) and then repeat, regardless of any time jumps. The \f(CW\*(C`offset\*(C'\fR |
|
|
2072 | argument is merely an offset into the \f(CW\*(C`interval\*(C'\fR periods. |
1215 | .Sp |
2073 | .Sp |
1216 | This can be used to create timers that do not drift with respect to system |
2074 | This can be used to create timers that do not drift with respect to the |
1217 | time: |
2075 | system clock, for example, here is an \f(CW\*(C`ev_periodic\*(C'\fR that triggers each |
|
|
2076 | hour, on the hour (with respect to \s-1UTC\s0): |
1218 | .Sp |
2077 | .Sp |
1219 | .Vb 1 |
2078 | .Vb 1 |
1220 | \& ev_periodic_set (&periodic, 0., 3600., 0); |
2079 | \& ev_periodic_set (&periodic, 0., 3600., 0); |
1221 | .Ve |
2080 | .Ve |
1222 | .Sp |
2081 | .Sp |
1223 | This doesn't mean there will always be 3600 seconds in between triggers, |
2082 | This doesn't mean there will always be 3600 seconds in between triggers, |
1224 | but only that the the callback will be called when the system time shows a |
2083 | but only that the callback will be called when the system time shows a |
1225 | full hour (\s-1UTC\s0), or more correctly, when the system time is evenly divisible |
2084 | full hour (\s-1UTC\s0), or more correctly, when the system time is evenly divisible |
1226 | by 3600. |
2085 | by 3600. |
1227 | .Sp |
2086 | .Sp |
1228 | Another way to think about it (for the mathematically inclined) is that |
2087 | Another way to think about it (for the mathematically inclined) is that |
1229 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
2088 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
1230 | time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps. |
2089 | time where \f(CW\*(C`time = offset (mod interval)\*(C'\fR, regardless of any time jumps. |
1231 | .IP "* manual reschedule mode (reschedule_cb = callback)" 4 |
2090 | .Sp |
1232 | .IX Item "manual reschedule mode (reschedule_cb = callback)" |
2091 | For numerical stability it is preferable that the \f(CW\*(C`offset\*(C'\fR value is near |
|
|
2092 | \&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for |
|
|
2093 | this value, and in fact is often specified as zero. |
|
|
2094 | .Sp |
|
|
2095 | Note also that there is an upper limit to how often a timer can fire (\s-1CPU\s0 |
|
|
2096 | speed for example), so if \f(CW\*(C`interval\*(C'\fR is very small then timing stability |
|
|
2097 | will of course deteriorate. Libev itself tries to be exact to be about one |
|
|
2098 | millisecond (if the \s-1OS\s0 supports it and the machine is fast enough). |
|
|
2099 | .IP "\(bu" 4 |
|
|
2100 | manual reschedule mode (offset ignored, interval ignored, reschedule_cb = callback) |
|
|
2101 | .Sp |
1233 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being |
2102 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`offset\*(C'\fR are both being |
1234 | ignored. Instead, each time the periodic watcher gets scheduled, the |
2103 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1235 | reschedule callback will be called with the watcher as first, and the |
2104 | reschedule callback will be called with the watcher as first, and the |
1236 | current time as second argument. |
2105 | current time as second argument. |
1237 | .Sp |
2106 | .Sp |
1238 | \&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, |
2107 | \&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, ever, |
1239 | ever, or make any event loop modifications\fR. If you need to stop it, |
2108 | or make \s-1ANY\s0 other event loop modifications whatsoever, unless explicitly |
1240 | return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop it afterwards (e.g. by |
2109 | allowed by documentation here\fR. |
1241 | starting a prepare watcher). |
|
|
1242 | .Sp |
2110 | .Sp |
|
|
2111 | If you need to stop it, return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop |
|
|
2112 | it afterwards (e.g. by starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is the |
|
|
2113 | only event loop modification you are allowed to do). |
|
|
2114 | .Sp |
1243 | Its prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
2115 | The callback prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(ev_periodic |
1244 | ev_tstamp now)\*(C'\fR, e.g.: |
2116 | *w, ev_tstamp now)\*(C'\fR, e.g.: |
1245 | .Sp |
2117 | .Sp |
1246 | .Vb 4 |
2118 | .Vb 5 |
|
|
2119 | \& static ev_tstamp |
1247 | \& static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
2120 | \& my_rescheduler (ev_periodic *w, ev_tstamp now) |
1248 | \& { |
2121 | \& { |
1249 | \& return now + 60.; |
2122 | \& return now + 60.; |
1250 | \& } |
2123 | \& } |
1251 | .Ve |
2124 | .Ve |
1252 | .Sp |
2125 | .Sp |
1253 | It must return the next time to trigger, based on the passed time value |
2126 | It must return the next time to trigger, based on the passed time value |
1254 | (that is, the lowest time value larger than to the second argument). It |
2127 | (that is, the lowest time value larger than to the second argument). It |
1255 | will usually be called just before the callback will be triggered, but |
2128 | will usually be called just before the callback will be triggered, but |
1256 | might be called at other times, too. |
2129 | might be called at other times, too. |
1257 | .Sp |
2130 | .Sp |
1258 | \&\s-1NOTE:\s0 \fIThis callback must always return a time that is later than the |
2131 | \&\s-1NOTE:\s0 \fIThis callback must always return a time that is higher than or |
1259 | passed \f(CI\*(C`now\*(C'\fI value\fR. Not even \f(CW\*(C`now\*(C'\fR itself will do, it \fImust\fR be larger. |
2132 | equal to the passed \f(CI\*(C`now\*(C'\fI value\fR. |
1260 | .Sp |
2133 | .Sp |
1261 | This can be used to create very complex timers, such as a timer that |
2134 | This can be used to create very complex timers, such as a timer that |
1262 | triggers on each midnight, local time. To do this, you would calculate the |
2135 | triggers on \*(L"next midnight, local time\*(R". To do this, you would calculate the |
1263 | next midnight after \f(CW\*(C`now\*(C'\fR and return the timestamp value for this. How |
2136 | next midnight after \f(CW\*(C`now\*(C'\fR and return the timestamp value for this. How |
1264 | you do this is, again, up to you (but it is not trivial, which is the main |
2137 | you do this is, again, up to you (but it is not trivial, which is the main |
1265 | reason I omitted it as an example). |
2138 | reason I omitted it as an example). |
1266 | .RE |
2139 | .RE |
1267 | .RS 4 |
2140 | .RS 4 |
… | |
… | |
1270 | .IX Item "ev_periodic_again (loop, ev_periodic *)" |
2143 | .IX Item "ev_periodic_again (loop, ev_periodic *)" |
1271 | Simply stops and restarts the periodic watcher again. This is only useful |
2144 | Simply stops and restarts the periodic watcher again. This is only useful |
1272 | when you changed some parameters or the reschedule callback would return |
2145 | when you changed some parameters or the reschedule callback would return |
1273 | a different time than the last time it was called (e.g. in a crond like |
2146 | a different time than the last time it was called (e.g. in a crond like |
1274 | program when the crontabs have changed). |
2147 | program when the crontabs have changed). |
|
|
2148 | .IP "ev_tstamp ev_periodic_at (ev_periodic *)" 4 |
|
|
2149 | .IX Item "ev_tstamp ev_periodic_at (ev_periodic *)" |
|
|
2150 | When active, returns the absolute time that the watcher is supposed |
|
|
2151 | to trigger next. This is not the same as the \f(CW\*(C`offset\*(C'\fR argument to |
|
|
2152 | \&\f(CW\*(C`ev_periodic_set\*(C'\fR, but indeed works even in interval and manual |
|
|
2153 | rescheduling modes. |
|
|
2154 | .IP "ev_tstamp offset [read\-write]" 4 |
|
|
2155 | .IX Item "ev_tstamp offset [read-write]" |
|
|
2156 | When repeating, this contains the offset value, otherwise this is the |
|
|
2157 | absolute point in time (the \f(CW\*(C`offset\*(C'\fR value passed to \f(CW\*(C`ev_periodic_set\*(C'\fR, |
|
|
2158 | although libev might modify this value for better numerical stability). |
|
|
2159 | .Sp |
|
|
2160 | Can be modified any time, but changes only take effect when the periodic |
|
|
2161 | timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. |
1275 | .IP "ev_tstamp interval [read\-write]" 4 |
2162 | .IP "ev_tstamp interval [read\-write]" 4 |
1276 | .IX Item "ev_tstamp interval [read-write]" |
2163 | .IX Item "ev_tstamp interval [read-write]" |
1277 | The current interval value. Can be modified any time, but changes only |
2164 | The current interval value. Can be modified any time, but changes only |
1278 | take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being |
2165 | take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being |
1279 | called. |
2166 | called. |
1280 | .IP "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read\-write]" 4 |
2167 | .IP "ev_tstamp (*reschedule_cb)(ev_periodic *w, ev_tstamp now) [read\-write]" 4 |
1281 | .IX Item "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]" |
2168 | .IX Item "ev_tstamp (*reschedule_cb)(ev_periodic *w, ev_tstamp now) [read-write]" |
1282 | The current reschedule callback, or \f(CW0\fR, if this functionality is |
2169 | The current reschedule callback, or \f(CW0\fR, if this functionality is |
1283 | switched off. Can be changed any time, but changes only take effect when |
2170 | switched off. Can be changed any time, but changes only take effect when |
1284 | the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. |
2171 | the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. |
1285 | .PP |
2172 | .PP |
|
|
2173 | \fIExamples\fR |
|
|
2174 | .IX Subsection "Examples" |
|
|
2175 | .PP |
1286 | Example: Call a callback every hour, or, more precisely, whenever the |
2176 | Example: Call a callback every hour, or, more precisely, whenever the |
1287 | system clock is divisible by 3600. The callback invocation times have |
2177 | system time is divisible by 3600. The callback invocation times have |
1288 | potentially a lot of jittering, but good long-term stability. |
2178 | potentially a lot of jitter, but good long-term stability. |
1289 | .PP |
2179 | .PP |
1290 | .Vb 5 |
2180 | .Vb 5 |
1291 | \& static void |
2181 | \& static void |
1292 | \& clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
2182 | \& clock_cb (struct ev_loop *loop, ev_io *w, int revents) |
1293 | \& { |
2183 | \& { |
1294 | \& ... its now a full hour (UTC, or TAI or whatever your clock follows) |
2184 | \& ... its now a full hour (UTC, or TAI or whatever your clock follows) |
1295 | \& } |
2185 | \& } |
1296 | .Ve |
2186 | \& |
1297 | .PP |
|
|
1298 | .Vb 3 |
|
|
1299 | \& struct ev_periodic hourly_tick; |
2187 | \& ev_periodic hourly_tick; |
1300 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
2188 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1301 | \& ev_periodic_start (loop, &hourly_tick); |
2189 | \& ev_periodic_start (loop, &hourly_tick); |
1302 | .Ve |
2190 | .Ve |
1303 | .PP |
2191 | .PP |
1304 | Example: The same as above, but use a reschedule callback to do it: |
2192 | Example: The same as above, but use a reschedule callback to do it: |
1305 | .PP |
2193 | .PP |
1306 | .Vb 1 |
2194 | .Vb 1 |
1307 | \& #include <math.h> |
2195 | \& #include <math.h> |
1308 | .Ve |
2196 | \& |
1309 | .PP |
|
|
1310 | .Vb 5 |
|
|
1311 | \& static ev_tstamp |
2197 | \& static ev_tstamp |
1312 | \& my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
2198 | \& my_scheduler_cb (ev_periodic *w, ev_tstamp now) |
1313 | \& { |
2199 | \& { |
1314 | \& return fmod (now, 3600.) + 3600.; |
2200 | \& return now + (3600. \- fmod (now, 3600.)); |
1315 | \& } |
2201 | \& } |
1316 | .Ve |
2202 | \& |
1317 | .PP |
|
|
1318 | .Vb 1 |
|
|
1319 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
2203 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1320 | .Ve |
2204 | .Ve |
1321 | .PP |
2205 | .PP |
1322 | Example: Call a callback every hour, starting now: |
2206 | Example: Call a callback every hour, starting now: |
1323 | .PP |
2207 | .PP |
1324 | .Vb 4 |
2208 | .Vb 4 |
1325 | \& struct ev_periodic hourly_tick; |
2209 | \& ev_periodic hourly_tick; |
1326 | \& ev_periodic_init (&hourly_tick, clock_cb, |
2210 | \& ev_periodic_init (&hourly_tick, clock_cb, |
1327 | \& fmod (ev_now (loop), 3600.), 3600., 0); |
2211 | \& fmod (ev_now (loop), 3600.), 3600., 0); |
1328 | \& ev_periodic_start (loop, &hourly_tick); |
2212 | \& ev_periodic_start (loop, &hourly_tick); |
1329 | .Ve |
2213 | .Ve |
1330 | .ie n .Sh """ev_signal"" \- signal me when a signal gets signalled!" |
2214 | .ie n .SS """ev_signal"" \- signal me when a signal gets signalled!" |
1331 | .el .Sh "\f(CWev_signal\fP \- signal me when a signal gets signalled!" |
2215 | .el .SS "\f(CWev_signal\fP \- signal me when a signal gets signalled!" |
1332 | .IX Subsection "ev_signal - signal me when a signal gets signalled!" |
2216 | .IX Subsection "ev_signal - signal me when a signal gets signalled!" |
1333 | Signal watchers will trigger an event when the process receives a specific |
2217 | Signal watchers will trigger an event when the process receives a specific |
1334 | signal one or more times. Even though signals are very asynchronous, libev |
2218 | signal one or more times. Even though signals are very asynchronous, libev |
1335 | will try it's best to deliver signals synchronously, i.e. as part of the |
2219 | will try it's best to deliver signals synchronously, i.e. as part of the |
1336 | normal event processing, like any other event. |
2220 | normal event processing, like any other event. |
1337 | .PP |
2221 | .PP |
|
|
2222 | If you want signals asynchronously, just use \f(CW\*(C`sigaction\*(C'\fR as you would |
|
|
2223 | do without libev and forget about sharing the signal. You can even use |
|
|
2224 | \&\f(CW\*(C`ev_async\*(C'\fR from a signal handler to synchronously wake up an event loop. |
|
|
2225 | .PP |
1338 | You can configure as many watchers as you like per signal. Only when the |
2226 | You can configure as many watchers as you like per signal. Only when the |
1339 | first watcher gets started will libev actually register a signal watcher |
2227 | first watcher gets started will libev actually register a signal handler |
1340 | with the kernel (thus it coexists with your own signal handlers as long |
2228 | with the kernel (thus it coexists with your own signal handlers as long as |
1341 | as you don't register any with libev). Similarly, when the last signal |
2229 | you don't register any with libev for the same signal). Similarly, when |
1342 | watcher for a signal is stopped libev will reset the signal handler to |
2230 | the last signal watcher for a signal is stopped, libev will reset the |
1343 | \&\s-1SIG_DFL\s0 (regardless of what it was set to before). |
2231 | signal handler to \s-1SIG_DFL\s0 (regardless of what it was set to before). |
|
|
2232 | .PP |
|
|
2233 | If possible and supported, libev will install its handlers with |
|
|
2234 | \&\f(CW\*(C`SA_RESTART\*(C'\fR behaviour enabled, so system calls should not be unduly |
|
|
2235 | interrupted. If you have a problem with system calls getting interrupted by |
|
|
2236 | signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher and unblock |
|
|
2237 | them in an \f(CW\*(C`ev_prepare\*(C'\fR watcher. |
|
|
2238 | .PP |
|
|
2239 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
2240 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1344 | .IP "ev_signal_init (ev_signal *, callback, int signum)" 4 |
2241 | .IP "ev_signal_init (ev_signal *, callback, int signum)" 4 |
1345 | .IX Item "ev_signal_init (ev_signal *, callback, int signum)" |
2242 | .IX Item "ev_signal_init (ev_signal *, callback, int signum)" |
1346 | .PD 0 |
2243 | .PD 0 |
1347 | .IP "ev_signal_set (ev_signal *, int signum)" 4 |
2244 | .IP "ev_signal_set (ev_signal *, int signum)" 4 |
1348 | .IX Item "ev_signal_set (ev_signal *, int signum)" |
2245 | .IX Item "ev_signal_set (ev_signal *, int signum)" |
… | |
… | |
1350 | Configures the watcher to trigger on the given signal number (usually one |
2247 | Configures the watcher to trigger on the given signal number (usually one |
1351 | of the \f(CW\*(C`SIGxxx\*(C'\fR constants). |
2248 | of the \f(CW\*(C`SIGxxx\*(C'\fR constants). |
1352 | .IP "int signum [read\-only]" 4 |
2249 | .IP "int signum [read\-only]" 4 |
1353 | .IX Item "int signum [read-only]" |
2250 | .IX Item "int signum [read-only]" |
1354 | The signal the watcher watches out for. |
2251 | The signal the watcher watches out for. |
|
|
2252 | .PP |
|
|
2253 | \fIExamples\fR |
|
|
2254 | .IX Subsection "Examples" |
|
|
2255 | .PP |
|
|
2256 | Example: Try to exit cleanly on \s-1SIGINT\s0. |
|
|
2257 | .PP |
|
|
2258 | .Vb 5 |
|
|
2259 | \& static void |
|
|
2260 | \& sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
|
|
2261 | \& { |
|
|
2262 | \& ev_unloop (loop, EVUNLOOP_ALL); |
|
|
2263 | \& } |
|
|
2264 | \& |
|
|
2265 | \& ev_signal signal_watcher; |
|
|
2266 | \& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
|
|
2267 | \& ev_signal_start (loop, &signal_watcher); |
|
|
2268 | .Ve |
1355 | .ie n .Sh """ev_child"" \- watch out for process status changes" |
2269 | .ie n .SS """ev_child"" \- watch out for process status changes" |
1356 | .el .Sh "\f(CWev_child\fP \- watch out for process status changes" |
2270 | .el .SS "\f(CWev_child\fP \- watch out for process status changes" |
1357 | .IX Subsection "ev_child - watch out for process status changes" |
2271 | .IX Subsection "ev_child - watch out for process status changes" |
1358 | Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to |
2272 | Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to |
1359 | some child status changes (most typically when a child of yours dies). |
2273 | some child status changes (most typically when a child of yours dies or |
|
|
2274 | exits). It is permissible to install a child watcher \fIafter\fR the child |
|
|
2275 | has been forked (which implies it might have already exited), as long |
|
|
2276 | as the event loop isn't entered (or is continued from a watcher), i.e., |
|
|
2277 | forking and then immediately registering a watcher for the child is fine, |
|
|
2278 | but forking and registering a watcher a few event loop iterations later or |
|
|
2279 | in the next callback invocation is not. |
|
|
2280 | .PP |
|
|
2281 | Only the default event loop is capable of handling signals, and therefore |
|
|
2282 | you can only register child watchers in the default event loop. |
|
|
2283 | .PP |
|
|
2284 | Due to some design glitches inside libev, child watchers will always be |
|
|
2285 | handled at maximum priority (their priority is set to \f(CW\*(C`EV_MAXPRI\*(C'\fR by |
|
|
2286 | libev) |
|
|
2287 | .PP |
|
|
2288 | \fIProcess Interaction\fR |
|
|
2289 | .IX Subsection "Process Interaction" |
|
|
2290 | .PP |
|
|
2291 | Libev grabs \f(CW\*(C`SIGCHLD\*(C'\fR as soon as the default event loop is |
|
|
2292 | initialised. This is necessary to guarantee proper behaviour even if |
|
|
2293 | the first child watcher is started after the child exits. The occurrence |
|
|
2294 | of \f(CW\*(C`SIGCHLD\*(C'\fR is recorded asynchronously, but child reaping is done |
|
|
2295 | synchronously as part of the event loop processing. Libev always reaps all |
|
|
2296 | children, even ones not watched. |
|
|
2297 | .PP |
|
|
2298 | \fIOverriding the Built-In Processing\fR |
|
|
2299 | .IX Subsection "Overriding the Built-In Processing" |
|
|
2300 | .PP |
|
|
2301 | Libev offers no special support for overriding the built-in child |
|
|
2302 | processing, but if your application collides with libev's default child |
|
|
2303 | handler, you can override it easily by installing your own handler for |
|
|
2304 | \&\f(CW\*(C`SIGCHLD\*(C'\fR after initialising the default loop, and making sure the |
|
|
2305 | default loop never gets destroyed. You are encouraged, however, to use an |
|
|
2306 | event-based approach to child reaping and thus use libev's support for |
|
|
2307 | that, so other libev users can use \f(CW\*(C`ev_child\*(C'\fR watchers freely. |
|
|
2308 | .PP |
|
|
2309 | \fIStopping the Child Watcher\fR |
|
|
2310 | .IX Subsection "Stopping the Child Watcher" |
|
|
2311 | .PP |
|
|
2312 | Currently, the child watcher never gets stopped, even when the |
|
|
2313 | child terminates, so normally one needs to stop the watcher in the |
|
|
2314 | callback. Future versions of libev might stop the watcher automatically |
|
|
2315 | when a child exit is detected. |
|
|
2316 | .PP |
|
|
2317 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
2318 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1360 | .IP "ev_child_init (ev_child *, callback, int pid)" 4 |
2319 | .IP "ev_child_init (ev_child *, callback, int pid, int trace)" 4 |
1361 | .IX Item "ev_child_init (ev_child *, callback, int pid)" |
2320 | .IX Item "ev_child_init (ev_child *, callback, int pid, int trace)" |
1362 | .PD 0 |
2321 | .PD 0 |
1363 | .IP "ev_child_set (ev_child *, int pid)" 4 |
2322 | .IP "ev_child_set (ev_child *, int pid, int trace)" 4 |
1364 | .IX Item "ev_child_set (ev_child *, int pid)" |
2323 | .IX Item "ev_child_set (ev_child *, int pid, int trace)" |
1365 | .PD |
2324 | .PD |
1366 | Configures the watcher to wait for status changes of process \f(CW\*(C`pid\*(C'\fR (or |
2325 | Configures the watcher to wait for status changes of process \f(CW\*(C`pid\*(C'\fR (or |
1367 | \&\fIany\fR process if \f(CW\*(C`pid\*(C'\fR is specified as \f(CW0\fR). The callback can look |
2326 | \&\fIany\fR process if \f(CW\*(C`pid\*(C'\fR is specified as \f(CW0\fR). The callback can look |
1368 | at the \f(CW\*(C`rstatus\*(C'\fR member of the \f(CW\*(C`ev_child\*(C'\fR watcher structure to see |
2327 | at the \f(CW\*(C`rstatus\*(C'\fR member of the \f(CW\*(C`ev_child\*(C'\fR watcher structure to see |
1369 | the status word (use the macros from \f(CW\*(C`sys/wait.h\*(C'\fR and see your systems |
2328 | the status word (use the macros from \f(CW\*(C`sys/wait.h\*(C'\fR and see your systems |
1370 | \&\f(CW\*(C`waitpid\*(C'\fR documentation). The \f(CW\*(C`rpid\*(C'\fR member contains the pid of the |
2329 | \&\f(CW\*(C`waitpid\*(C'\fR documentation). The \f(CW\*(C`rpid\*(C'\fR member contains the pid of the |
1371 | process causing the status change. |
2330 | process causing the status change. \f(CW\*(C`trace\*(C'\fR must be either \f(CW0\fR (only |
|
|
2331 | activate the watcher when the process terminates) or \f(CW1\fR (additionally |
|
|
2332 | activate the watcher when the process is stopped or continued). |
1372 | .IP "int pid [read\-only]" 4 |
2333 | .IP "int pid [read\-only]" 4 |
1373 | .IX Item "int pid [read-only]" |
2334 | .IX Item "int pid [read-only]" |
1374 | The process id this watcher watches out for, or \f(CW0\fR, meaning any process id. |
2335 | The process id this watcher watches out for, or \f(CW0\fR, meaning any process id. |
1375 | .IP "int rpid [read\-write]" 4 |
2336 | .IP "int rpid [read\-write]" 4 |
1376 | .IX Item "int rpid [read-write]" |
2337 | .IX Item "int rpid [read-write]" |
… | |
… | |
1378 | .IP "int rstatus [read\-write]" 4 |
2339 | .IP "int rstatus [read\-write]" 4 |
1379 | .IX Item "int rstatus [read-write]" |
2340 | .IX Item "int rstatus [read-write]" |
1380 | The process exit/trace status caused by \f(CW\*(C`rpid\*(C'\fR (see your systems |
2341 | The process exit/trace status caused by \f(CW\*(C`rpid\*(C'\fR (see your systems |
1381 | \&\f(CW\*(C`waitpid\*(C'\fR and \f(CW\*(C`sys/wait.h\*(C'\fR documentation for details). |
2342 | \&\f(CW\*(C`waitpid\*(C'\fR and \f(CW\*(C`sys/wait.h\*(C'\fR documentation for details). |
1382 | .PP |
2343 | .PP |
1383 | Example: Try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0. |
2344 | \fIExamples\fR |
|
|
2345 | .IX Subsection "Examples" |
1384 | .PP |
2346 | .PP |
|
|
2347 | Example: \f(CW\*(C`fork()\*(C'\fR a new process and install a child handler to wait for |
|
|
2348 | its completion. |
|
|
2349 | .PP |
1385 | .Vb 5 |
2350 | .Vb 1 |
|
|
2351 | \& ev_child cw; |
|
|
2352 | \& |
1386 | \& static void |
2353 | \& static void |
1387 | \& sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
2354 | \& child_cb (EV_P_ ev_child *w, int revents) |
1388 | \& { |
2355 | \& { |
1389 | \& ev_unloop (loop, EVUNLOOP_ALL); |
2356 | \& ev_child_stop (EV_A_ w); |
|
|
2357 | \& printf ("process %d exited with status %x\en", w\->rpid, w\->rstatus); |
1390 | \& } |
2358 | \& } |
|
|
2359 | \& |
|
|
2360 | \& pid_t pid = fork (); |
|
|
2361 | \& |
|
|
2362 | \& if (pid < 0) |
|
|
2363 | \& // error |
|
|
2364 | \& else if (pid == 0) |
|
|
2365 | \& { |
|
|
2366 | \& // the forked child executes here |
|
|
2367 | \& exit (1); |
|
|
2368 | \& } |
|
|
2369 | \& else |
|
|
2370 | \& { |
|
|
2371 | \& ev_child_init (&cw, child_cb, pid, 0); |
|
|
2372 | \& ev_child_start (EV_DEFAULT_ &cw); |
|
|
2373 | \& } |
1391 | .Ve |
2374 | .Ve |
1392 | .PP |
|
|
1393 | .Vb 3 |
|
|
1394 | \& struct ev_signal signal_watcher; |
|
|
1395 | \& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
|
|
1396 | \& ev_signal_start (loop, &sigint_cb); |
|
|
1397 | .Ve |
|
|
1398 | .ie n .Sh """ev_stat"" \- did the file attributes just change?" |
2375 | .ie n .SS """ev_stat"" \- did the file attributes just change?" |
1399 | .el .Sh "\f(CWev_stat\fP \- did the file attributes just change?" |
2376 | .el .SS "\f(CWev_stat\fP \- did the file attributes just change?" |
1400 | .IX Subsection "ev_stat - did the file attributes just change?" |
2377 | .IX Subsection "ev_stat - did the file attributes just change?" |
1401 | This watches a filesystem path for attribute changes. That is, it calls |
2378 | This watches a file system path for attribute changes. That is, it calls |
1402 | \&\f(CW\*(C`stat\*(C'\fR regularly (or when the \s-1OS\s0 says it changed) and sees if it changed |
2379 | \&\f(CW\*(C`stat\*(C'\fR on that path in regular intervals (or when the \s-1OS\s0 says it changed) |
1403 | compared to the last time, invoking the callback if it did. |
2380 | and sees if it changed compared to the last time, invoking the callback if |
|
|
2381 | it did. |
1404 | .PP |
2382 | .PP |
1405 | The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does |
2383 | The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does |
1406 | not exist\*(R" is a status change like any other. The condition \*(L"path does |
2384 | not exist\*(R" is a status change like any other. The condition \*(L"path does not |
1407 | not exist\*(R" is signified by the \f(CW\*(C`st_nlink\*(C'\fR field being zero (which is |
2385 | exist\*(R" (or more correctly \*(L"path cannot be stat'ed\*(R") is signified by the |
1408 | otherwise always forced to be at least one) and all the other fields of |
2386 | \&\f(CW\*(C`st_nlink\*(C'\fR field being zero (which is otherwise always forced to be at |
1409 | the stat buffer having unspecified contents. |
2387 | least one) and all the other fields of the stat buffer having unspecified |
|
|
2388 | contents. |
1410 | .PP |
2389 | .PP |
1411 | The path \fIshould\fR be absolute and \fImust not\fR end in a slash. If it is |
2390 | The path \fImust not\fR end in a slash or contain special components such as |
|
|
2391 | \&\f(CW\*(C`.\*(C'\fR or \f(CW\*(C`..\*(C'\fR. The path \fIshould\fR be absolute: If it is relative and |
1412 | relative and your working directory changes, the behaviour is undefined. |
2392 | your working directory changes, then the behaviour is undefined. |
1413 | .PP |
2393 | .PP |
1414 | Since there is no standard to do this, the portable implementation simply |
2394 | Since there is no portable change notification interface available, the |
1415 | calls \f(CW\*(C`stat (2)\*(C'\fR regularly on the path to see if it changed somehow. You |
2395 | portable implementation simply calls \f(CWstat(2)\fR regularly on the path |
1416 | can specify a recommended polling interval for this case. If you specify |
2396 | to see if it changed somehow. You can specify a recommended polling |
1417 | a polling interval of \f(CW0\fR (highly recommended!) then a \fIsuitable, |
2397 | interval for this case. If you specify a polling interval of \f(CW0\fR (highly |
1418 | unspecified default\fR value will be used (which you can expect to be around |
2398 | recommended!) then a \fIsuitable, unspecified default\fR value will be used |
1419 | five seconds, although this might change dynamically). Libev will also |
2399 | (which you can expect to be around five seconds, although this might |
1420 | impose a minimum interval which is currently around \f(CW0.1\fR, but thats |
2400 | change dynamically). Libev will also impose a minimum interval which is |
1421 | usually overkill. |
2401 | currently around \f(CW0.1\fR, but that's usually overkill. |
1422 | .PP |
2402 | .PP |
1423 | This watcher type is not meant for massive numbers of stat watchers, |
2403 | This watcher type is not meant for massive numbers of stat watchers, |
1424 | as even with OS-supported change notifications, this can be |
2404 | as even with OS-supported change notifications, this can be |
1425 | resource\-intensive. |
2405 | resource-intensive. |
1426 | .PP |
2406 | .PP |
1427 | At the time of this writing, only the Linux inotify interface is |
2407 | At the time of this writing, the only OS-specific interface implemented |
1428 | implemented (implementing kqueue support is left as an exercise for the |
2408 | is the Linux inotify interface (implementing kqueue support is left as an |
1429 | reader). Inotify will be used to give hints only and should not change the |
2409 | exercise for the reader. Note, however, that the author sees no way of |
1430 | semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers, which means that libev sometimes needs |
2410 | implementing \f(CW\*(C`ev_stat\*(C'\fR semantics with kqueue, except as a hint). |
1431 | to fall back to regular polling again even with inotify, but changes are |
2411 | .PP |
1432 | usually detected immediately, and if the file exists there will be no |
2412 | \fI\s-1ABI\s0 Issues (Largefile Support)\fR |
1433 | polling. |
2413 | .IX Subsection "ABI Issues (Largefile Support)" |
|
|
2414 | .PP |
|
|
2415 | Libev by default (unless the user overrides this) uses the default |
|
|
2416 | compilation environment, which means that on systems with large file |
|
|
2417 | support disabled by default, you get the 32 bit version of the stat |
|
|
2418 | structure. When using the library from programs that change the \s-1ABI\s0 to |
|
|
2419 | use 64 bit file offsets the programs will fail. In that case you have to |
|
|
2420 | compile libev with the same flags to get binary compatibility. This is |
|
|
2421 | obviously the case with any flags that change the \s-1ABI\s0, but the problem is |
|
|
2422 | most noticeably displayed with ev_stat and large file support. |
|
|
2423 | .PP |
|
|
2424 | The solution for this is to lobby your distribution maker to make large |
|
|
2425 | file interfaces available by default (as e.g. FreeBSD does) and not |
|
|
2426 | optional. Libev cannot simply switch on large file support because it has |
|
|
2427 | to exchange stat structures with application programs compiled using the |
|
|
2428 | default compilation environment. |
|
|
2429 | .PP |
|
|
2430 | \fIInotify and Kqueue\fR |
|
|
2431 | .IX Subsection "Inotify and Kqueue" |
|
|
2432 | .PP |
|
|
2433 | When \f(CW\*(C`inotify (7)\*(C'\fR support has been compiled into libev and present at |
|
|
2434 | runtime, it will be used to speed up change detection where possible. The |
|
|
2435 | inotify descriptor will be created lazily when the first \f(CW\*(C`ev_stat\*(C'\fR |
|
|
2436 | watcher is being started. |
|
|
2437 | .PP |
|
|
2438 | Inotify presence does not change the semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers |
|
|
2439 | except that changes might be detected earlier, and in some cases, to avoid |
|
|
2440 | making regular \f(CW\*(C`stat\*(C'\fR calls. Even in the presence of inotify support |
|
|
2441 | there are many cases where libev has to resort to regular \f(CW\*(C`stat\*(C'\fR polling, |
|
|
2442 | but as long as kernel 2.6.25 or newer is used (2.6.24 and older have too |
|
|
2443 | many bugs), the path exists (i.e. stat succeeds), and the path resides on |
|
|
2444 | a local filesystem (libev currently assumes only ext2/3, jfs, reiserfs and |
|
|
2445 | xfs are fully working) libev usually gets away without polling. |
|
|
2446 | .PP |
|
|
2447 | There is no support for kqueue, as apparently it cannot be used to |
|
|
2448 | implement this functionality, due to the requirement of having a file |
|
|
2449 | descriptor open on the object at all times, and detecting renames, unlinks |
|
|
2450 | etc. is difficult. |
|
|
2451 | .PP |
|
|
2452 | \fI\f(CI\*(C`stat ()\*(C'\fI is a synchronous operation\fR |
|
|
2453 | .IX Subsection "stat () is a synchronous operation" |
|
|
2454 | .PP |
|
|
2455 | Libev doesn't normally do any kind of I/O itself, and so is not blocking |
|
|
2456 | the process. The exception are \f(CW\*(C`ev_stat\*(C'\fR watchers \- those call \f(CW\*(C`stat |
|
|
2457 | ()\*(C'\fR, which is a synchronous operation. |
|
|
2458 | .PP |
|
|
2459 | For local paths, this usually doesn't matter: unless the system is very |
|
|
2460 | busy or the intervals between stat's are large, a stat call will be fast, |
|
|
2461 | as the path data is usually in memory already (except when starting the |
|
|
2462 | watcher). |
|
|
2463 | .PP |
|
|
2464 | For networked file systems, calling \f(CW\*(C`stat ()\*(C'\fR can block an indefinite |
|
|
2465 | time due to network issues, and even under good conditions, a stat call |
|
|
2466 | often takes multiple milliseconds. |
|
|
2467 | .PP |
|
|
2468 | Therefore, it is best to avoid using \f(CW\*(C`ev_stat\*(C'\fR watchers on networked |
|
|
2469 | paths, although this is fully supported by libev. |
|
|
2470 | .PP |
|
|
2471 | \fIThe special problem of stat time resolution\fR |
|
|
2472 | .IX Subsection "The special problem of stat time resolution" |
|
|
2473 | .PP |
|
|
2474 | The \f(CW\*(C`stat ()\*(C'\fR system call only supports full-second resolution portably, |
|
|
2475 | and even on systems where the resolution is higher, most file systems |
|
|
2476 | still only support whole seconds. |
|
|
2477 | .PP |
|
|
2478 | That means that, if the time is the only thing that changes, you can |
|
|
2479 | easily miss updates: on the first update, \f(CW\*(C`ev_stat\*(C'\fR detects a change and |
|
|
2480 | calls your callback, which does something. When there is another update |
|
|
2481 | within the same second, \f(CW\*(C`ev_stat\*(C'\fR will be unable to detect unless the |
|
|
2482 | stat data does change in other ways (e.g. file size). |
|
|
2483 | .PP |
|
|
2484 | The solution to this is to delay acting on a change for slightly more |
|
|
2485 | than a second (or till slightly after the next full second boundary), using |
|
|
2486 | a roughly one-second-delay \f(CW\*(C`ev_timer\*(C'\fR (e.g. \f(CW\*(C`ev_timer_set (w, 0., 1.02); |
|
|
2487 | ev_timer_again (loop, w)\*(C'\fR). |
|
|
2488 | .PP |
|
|
2489 | The \f(CW.02\fR offset is added to work around small timing inconsistencies |
|
|
2490 | of some operating systems (where the second counter of the current time |
|
|
2491 | might be be delayed. One such system is the Linux kernel, where a call to |
|
|
2492 | \&\f(CW\*(C`gettimeofday\*(C'\fR might return a timestamp with a full second later than |
|
|
2493 | a subsequent \f(CW\*(C`time\*(C'\fR call \- if the equivalent of \f(CW\*(C`time ()\*(C'\fR is used to |
|
|
2494 | update file times then there will be a small window where the kernel uses |
|
|
2495 | the previous second to update file times but libev might already execute |
|
|
2496 | the timer callback). |
|
|
2497 | .PP |
|
|
2498 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
2499 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1434 | .IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4 |
2500 | .IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4 |
1435 | .IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" |
2501 | .IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" |
1436 | .PD 0 |
2502 | .PD 0 |
1437 | .IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4 |
2503 | .IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4 |
1438 | .IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" |
2504 | .IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" |
… | |
… | |
1441 | \&\f(CW\*(C`path\*(C'\fR. The \f(CW\*(C`interval\*(C'\fR is a hint on how quickly a change is expected to |
2507 | \&\f(CW\*(C`path\*(C'\fR. The \f(CW\*(C`interval\*(C'\fR is a hint on how quickly a change is expected to |
1442 | be detected and should normally be specified as \f(CW0\fR to let libev choose |
2508 | be detected and should normally be specified as \f(CW0\fR to let libev choose |
1443 | a suitable value. The memory pointed to by \f(CW\*(C`path\*(C'\fR must point to the same |
2509 | a suitable value. The memory pointed to by \f(CW\*(C`path\*(C'\fR must point to the same |
1444 | path for as long as the watcher is active. |
2510 | path for as long as the watcher is active. |
1445 | .Sp |
2511 | .Sp |
1446 | The callback will be receive \f(CW\*(C`EV_STAT\*(C'\fR when a change was detected, |
2512 | The callback will receive an \f(CW\*(C`EV_STAT\*(C'\fR event when a change was detected, |
1447 | relative to the attributes at the time the watcher was started (or the |
2513 | relative to the attributes at the time the watcher was started (or the |
1448 | last change was detected). |
2514 | last change was detected). |
1449 | .IP "ev_stat_stat (ev_stat *)" 4 |
2515 | .IP "ev_stat_stat (loop, ev_stat *)" 4 |
1450 | .IX Item "ev_stat_stat (ev_stat *)" |
2516 | .IX Item "ev_stat_stat (loop, ev_stat *)" |
1451 | Updates the stat buffer immediately with new values. If you change the |
2517 | Updates the stat buffer immediately with new values. If you change the |
1452 | watched path in your callback, you could call this fucntion to avoid |
2518 | watched path in your callback, you could call this function to avoid |
1453 | detecting this change (while introducing a race condition). Can also be |
2519 | detecting this change (while introducing a race condition if you are not |
1454 | useful simply to find out the new values. |
2520 | the only one changing the path). Can also be useful simply to find out the |
|
|
2521 | new values. |
1455 | .IP "ev_statdata attr [read\-only]" 4 |
2522 | .IP "ev_statdata attr [read\-only]" 4 |
1456 | .IX Item "ev_statdata attr [read-only]" |
2523 | .IX Item "ev_statdata attr [read-only]" |
1457 | The most-recently detected attributes of the file. Although the type is of |
2524 | The most-recently detected attributes of the file. Although the type is |
1458 | \&\f(CW\*(C`ev_statdata\*(C'\fR, this is usually the (or one of the) \f(CW\*(C`struct stat\*(C'\fR types |
2525 | \&\f(CW\*(C`ev_statdata\*(C'\fR, this is usually the (or one of the) \f(CW\*(C`struct stat\*(C'\fR types |
|
|
2526 | suitable for your system, but you can only rely on the POSIX-standardised |
1459 | suitable for your system. If the \f(CW\*(C`st_nlink\*(C'\fR member is \f(CW0\fR, then there |
2527 | members to be present. If the \f(CW\*(C`st_nlink\*(C'\fR member is \f(CW0\fR, then there was |
1460 | was some error while \f(CW\*(C`stat\*(C'\fRing the file. |
2528 | some error while \f(CW\*(C`stat\*(C'\fRing the file. |
1461 | .IP "ev_statdata prev [read\-only]" 4 |
2529 | .IP "ev_statdata prev [read\-only]" 4 |
1462 | .IX Item "ev_statdata prev [read-only]" |
2530 | .IX Item "ev_statdata prev [read-only]" |
1463 | The previous attributes of the file. The callback gets invoked whenever |
2531 | The previous attributes of the file. The callback gets invoked whenever |
1464 | \&\f(CW\*(C`prev\*(C'\fR != \f(CW\*(C`attr\*(C'\fR. |
2532 | \&\f(CW\*(C`prev\*(C'\fR != \f(CW\*(C`attr\*(C'\fR, or, more precisely, one or more of these members |
|
|
2533 | differ: \f(CW\*(C`st_dev\*(C'\fR, \f(CW\*(C`st_ino\*(C'\fR, \f(CW\*(C`st_mode\*(C'\fR, \f(CW\*(C`st_nlink\*(C'\fR, \f(CW\*(C`st_uid\*(C'\fR, |
|
|
2534 | \&\f(CW\*(C`st_gid\*(C'\fR, \f(CW\*(C`st_rdev\*(C'\fR, \f(CW\*(C`st_size\*(C'\fR, \f(CW\*(C`st_atime\*(C'\fR, \f(CW\*(C`st_mtime\*(C'\fR, \f(CW\*(C`st_ctime\*(C'\fR. |
1465 | .IP "ev_tstamp interval [read\-only]" 4 |
2535 | .IP "ev_tstamp interval [read\-only]" 4 |
1466 | .IX Item "ev_tstamp interval [read-only]" |
2536 | .IX Item "ev_tstamp interval [read-only]" |
1467 | The specified interval. |
2537 | The specified interval. |
1468 | .IP "const char *path [read\-only]" 4 |
2538 | .IP "const char *path [read\-only]" 4 |
1469 | .IX Item "const char *path [read-only]" |
2539 | .IX Item "const char *path [read-only]" |
1470 | The filesystem path that is being watched. |
2540 | The file system path that is being watched. |
|
|
2541 | .PP |
|
|
2542 | \fIExamples\fR |
|
|
2543 | .IX Subsection "Examples" |
1471 | .PP |
2544 | .PP |
1472 | Example: Watch \f(CW\*(C`/etc/passwd\*(C'\fR for attribute changes. |
2545 | Example: Watch \f(CW\*(C`/etc/passwd\*(C'\fR for attribute changes. |
1473 | .PP |
2546 | .PP |
1474 | .Vb 15 |
2547 | .Vb 10 |
1475 | \& static void |
2548 | \& static void |
1476 | \& passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
2549 | \& passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
1477 | \& { |
2550 | \& { |
1478 | \& /* /etc/passwd changed in some way */ |
2551 | \& /* /etc/passwd changed in some way */ |
1479 | \& if (w->attr.st_nlink) |
2552 | \& if (w\->attr.st_nlink) |
1480 | \& { |
2553 | \& { |
1481 | \& printf ("passwd current size %ld\en", (long)w->attr.st_size); |
2554 | \& printf ("passwd current size %ld\en", (long)w\->attr.st_size); |
1482 | \& printf ("passwd current atime %ld\en", (long)w->attr.st_mtime); |
2555 | \& printf ("passwd current atime %ld\en", (long)w\->attr.st_mtime); |
1483 | \& printf ("passwd current mtime %ld\en", (long)w->attr.st_mtime); |
2556 | \& printf ("passwd current mtime %ld\en", (long)w\->attr.st_mtime); |
1484 | \& } |
2557 | \& } |
1485 | \& else |
2558 | \& else |
1486 | \& /* you shalt not abuse printf for puts */ |
2559 | \& /* you shalt not abuse printf for puts */ |
1487 | \& puts ("wow, /etc/passwd is not there, expect problems. " |
2560 | \& puts ("wow, /etc/passwd is not there, expect problems. " |
1488 | \& "if this is windows, they already arrived\en"); |
2561 | \& "if this is windows, they already arrived\en"); |
1489 | \& } |
2562 | \& } |
|
|
2563 | \& |
|
|
2564 | \& ... |
|
|
2565 | \& ev_stat passwd; |
|
|
2566 | \& |
|
|
2567 | \& ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.); |
|
|
2568 | \& ev_stat_start (loop, &passwd); |
1490 | .Ve |
2569 | .Ve |
|
|
2570 | .PP |
|
|
2571 | Example: Like above, but additionally use a one-second delay so we do not |
|
|
2572 | miss updates (however, frequent updates will delay processing, too, so |
|
|
2573 | one might do the work both on \f(CW\*(C`ev_stat\*(C'\fR callback invocation \fIand\fR on |
|
|
2574 | \&\f(CW\*(C`ev_timer\*(C'\fR callback invocation). |
1491 | .PP |
2575 | .PP |
1492 | .Vb 2 |
2576 | .Vb 2 |
|
|
2577 | \& static ev_stat passwd; |
|
|
2578 | \& static ev_timer timer; |
|
|
2579 | \& |
|
|
2580 | \& static void |
|
|
2581 | \& timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
2582 | \& { |
|
|
2583 | \& ev_timer_stop (EV_A_ w); |
|
|
2584 | \& |
|
|
2585 | \& /* now it\*(Aqs one second after the most recent passwd change */ |
|
|
2586 | \& } |
|
|
2587 | \& |
|
|
2588 | \& static void |
|
|
2589 | \& stat_cb (EV_P_ ev_stat *w, int revents) |
|
|
2590 | \& { |
|
|
2591 | \& /* reset the one\-second timer */ |
|
|
2592 | \& ev_timer_again (EV_A_ &timer); |
|
|
2593 | \& } |
|
|
2594 | \& |
1493 | \& ... |
2595 | \& ... |
1494 | \& ev_stat passwd; |
|
|
1495 | .Ve |
|
|
1496 | .PP |
|
|
1497 | .Vb 2 |
|
|
1498 | \& ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
2596 | \& ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
1499 | \& ev_stat_start (loop, &passwd); |
2597 | \& ev_stat_start (loop, &passwd); |
|
|
2598 | \& ev_timer_init (&timer, timer_cb, 0., 1.02); |
1500 | .Ve |
2599 | .Ve |
1501 | .ie n .Sh """ev_idle"" \- when you've got nothing better to do..." |
2600 | .ie n .SS """ev_idle"" \- when you've got nothing better to do..." |
1502 | .el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..." |
2601 | .el .SS "\f(CWev_idle\fP \- when you've got nothing better to do..." |
1503 | .IX Subsection "ev_idle - when you've got nothing better to do..." |
2602 | .IX Subsection "ev_idle - when you've got nothing better to do..." |
1504 | Idle watchers trigger events when there are no other events are pending |
2603 | Idle watchers trigger events when no other events of the same or higher |
1505 | (prepare, check and other idle watchers do not count). That is, as long |
2604 | priority are pending (prepare, check and other idle watchers do not count |
1506 | as your process is busy handling sockets or timeouts (or even signals, |
2605 | as receiving \*(L"events\*(R"). |
1507 | imagine) it will not be triggered. But when your process is idle all idle |
2606 | .PP |
1508 | watchers are being called again and again, once per event loop iteration \- |
2607 | That is, as long as your process is busy handling sockets or timeouts |
|
|
2608 | (or even signals, imagine) of the same or higher priority it will not be |
|
|
2609 | triggered. But when your process is idle (or only lower-priority watchers |
|
|
2610 | are pending), the idle watchers are being called once per event loop |
1509 | until stopped, that is, or your process receives more events and becomes |
2611 | iteration \- until stopped, that is, or your process receives more events |
1510 | busy. |
2612 | and becomes busy again with higher priority stuff. |
1511 | .PP |
2613 | .PP |
1512 | The most noteworthy effect is that as long as any idle watchers are |
2614 | The most noteworthy effect is that as long as any idle watchers are |
1513 | active, the process will not block when waiting for new events. |
2615 | active, the process will not block when waiting for new events. |
1514 | .PP |
2616 | .PP |
1515 | Apart from keeping your process non-blocking (which is a useful |
2617 | Apart from keeping your process non-blocking (which is a useful |
1516 | effect on its own sometimes), idle watchers are a good place to do |
2618 | effect on its own sometimes), idle watchers are a good place to do |
1517 | \&\*(L"pseudo\-background processing\*(R", or delay processing stuff to after the |
2619 | \&\*(L"pseudo-background processing\*(R", or delay processing stuff to after the |
1518 | event loop has handled all outstanding events. |
2620 | event loop has handled all outstanding events. |
|
|
2621 | .PP |
|
|
2622 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
2623 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1519 | .IP "ev_idle_init (ev_signal *, callback)" 4 |
2624 | .IP "ev_idle_init (ev_idle *, callback)" 4 |
1520 | .IX Item "ev_idle_init (ev_signal *, callback)" |
2625 | .IX Item "ev_idle_init (ev_idle *, callback)" |
1521 | Initialises and configures the idle watcher \- it has no parameters of any |
2626 | Initialises and configures the idle watcher \- it has no parameters of any |
1522 | kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, |
2627 | kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, |
1523 | believe me. |
2628 | believe me. |
1524 | .PP |
2629 | .PP |
|
|
2630 | \fIExamples\fR |
|
|
2631 | .IX Subsection "Examples" |
|
|
2632 | .PP |
1525 | Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the |
2633 | Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the |
1526 | callback, free it. Also, use no error checking, as usual. |
2634 | callback, free it. Also, use no error checking, as usual. |
1527 | .PP |
2635 | .PP |
1528 | .Vb 7 |
2636 | .Vb 7 |
1529 | \& static void |
2637 | \& static void |
1530 | \& idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
2638 | \& idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
1531 | \& { |
2639 | \& { |
1532 | \& free (w); |
2640 | \& free (w); |
1533 | \& // now do something you wanted to do when the program has |
2641 | \& // now do something you wanted to do when the program has |
1534 | \& // no longer asnything immediate to do. |
2642 | \& // no longer anything immediate to do. |
1535 | \& } |
2643 | \& } |
1536 | .Ve |
2644 | \& |
1537 | .PP |
|
|
1538 | .Vb 3 |
|
|
1539 | \& struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
2645 | \& ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
1540 | \& ev_idle_init (idle_watcher, idle_cb); |
2646 | \& ev_idle_init (idle_watcher, idle_cb); |
1541 | \& ev_idle_start (loop, idle_cb); |
2647 | \& ev_idle_start (loop, idle_watcher); |
1542 | .Ve |
2648 | .Ve |
1543 | .ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop!" |
2649 | .ie n .SS """ev_prepare"" and ""ev_check"" \- customise your event loop!" |
1544 | .el .Sh "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!" |
2650 | .el .SS "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!" |
1545 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
2651 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
1546 | Prepare and check watchers are usually (but not always) used in tandem: |
2652 | Prepare and check watchers are usually (but not always) used in pairs: |
1547 | prepare watchers get invoked before the process blocks and check watchers |
2653 | prepare watchers get invoked before the process blocks and check watchers |
1548 | afterwards. |
2654 | afterwards. |
1549 | .PP |
2655 | .PP |
1550 | You \fImust not\fR call \f(CW\*(C`ev_loop\*(C'\fR or similar functions that enter |
2656 | You \fImust not\fR call \f(CW\*(C`ev_loop\*(C'\fR or similar functions that enter |
1551 | the current event loop from either \f(CW\*(C`ev_prepare\*(C'\fR or \f(CW\*(C`ev_check\*(C'\fR |
2657 | the current event loop from either \f(CW\*(C`ev_prepare\*(C'\fR or \f(CW\*(C`ev_check\*(C'\fR |
… | |
… | |
1554 | those watchers, i.e. the sequence will always be \f(CW\*(C`ev_prepare\*(C'\fR, blocking, |
2660 | those watchers, i.e. the sequence will always be \f(CW\*(C`ev_prepare\*(C'\fR, blocking, |
1555 | \&\f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each kind they will always be |
2661 | \&\f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each kind they will always be |
1556 | called in pairs bracketing the blocking call. |
2662 | called in pairs bracketing the blocking call. |
1557 | .PP |
2663 | .PP |
1558 | Their main purpose is to integrate other event mechanisms into libev and |
2664 | Their main purpose is to integrate other event mechanisms into libev and |
1559 | their use is somewhat advanced. This could be used, for example, to track |
2665 | their use is somewhat advanced. They could be used, for example, to track |
1560 | variable changes, implement your own watchers, integrate net-snmp or a |
2666 | variable changes, implement your own watchers, integrate net-snmp or a |
1561 | coroutine library and lots more. They are also occasionally useful if |
2667 | coroutine library and lots more. They are also occasionally useful if |
1562 | you cache some data and want to flush it before blocking (for example, |
2668 | you cache some data and want to flush it before blocking (for example, |
1563 | in X programs you might want to do an \f(CW\*(C`XFlush ()\*(C'\fR in an \f(CW\*(C`ev_prepare\*(C'\fR |
2669 | in X programs you might want to do an \f(CW\*(C`XFlush ()\*(C'\fR in an \f(CW\*(C`ev_prepare\*(C'\fR |
1564 | watcher). |
2670 | watcher). |
1565 | .PP |
2671 | .PP |
1566 | This is done by examining in each prepare call which file descriptors need |
2672 | This is done by examining in each prepare call which file descriptors |
1567 | to be watched by the other library, registering \f(CW\*(C`ev_io\*(C'\fR watchers for |
2673 | need to be watched by the other library, registering \f(CW\*(C`ev_io\*(C'\fR watchers |
1568 | them and starting an \f(CW\*(C`ev_timer\*(C'\fR watcher for any timeouts (many libraries |
2674 | for them and starting an \f(CW\*(C`ev_timer\*(C'\fR watcher for any timeouts (many |
1569 | provide just this functionality). Then, in the check watcher you check for |
2675 | libraries provide exactly this functionality). Then, in the check watcher, |
1570 | any events that occured (by checking the pending status of all watchers |
2676 | you check for any events that occurred (by checking the pending status |
1571 | and stopping them) and call back into the library. The I/O and timer |
2677 | of all watchers and stopping them) and call back into the library. The |
1572 | callbacks will never actually be called (but must be valid nevertheless, |
2678 | I/O and timer callbacks will never actually be called (but must be valid |
1573 | because you never know, you know?). |
2679 | nevertheless, because you never know, you know?). |
1574 | .PP |
2680 | .PP |
1575 | As another example, the Perl Coro module uses these hooks to integrate |
2681 | As another example, the Perl Coro module uses these hooks to integrate |
1576 | coroutines into libev programs, by yielding to other active coroutines |
2682 | coroutines into libev programs, by yielding to other active coroutines |
1577 | during each prepare and only letting the process block if no coroutines |
2683 | during each prepare and only letting the process block if no coroutines |
1578 | are ready to run (it's actually more complicated: it only runs coroutines |
2684 | are ready to run (it's actually more complicated: it only runs coroutines |
1579 | with priority higher than or equal to the event loop and one coroutine |
2685 | with priority higher than or equal to the event loop and one coroutine |
1580 | of lower priority, but only once, using idle watchers to keep the event |
2686 | of lower priority, but only once, using idle watchers to keep the event |
1581 | loop from blocking if lower-priority coroutines are active, thus mapping |
2687 | loop from blocking if lower-priority coroutines are active, thus mapping |
1582 | low-priority coroutines to idle/background tasks). |
2688 | low-priority coroutines to idle/background tasks). |
|
|
2689 | .PP |
|
|
2690 | It is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR) |
|
|
2691 | priority, to ensure that they are being run before any other watchers |
|
|
2692 | after the poll (this doesn't matter for \f(CW\*(C`ev_prepare\*(C'\fR watchers). |
|
|
2693 | .PP |
|
|
2694 | Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers, too) should not |
|
|
2695 | activate (\*(L"feed\*(R") events into libev. While libev fully supports this, they |
|
|
2696 | might get executed before other \f(CW\*(C`ev_check\*(C'\fR watchers did their job. As |
|
|
2697 | \&\f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other (non-libev) event |
|
|
2698 | loops those other event loops might be in an unusable state until their |
|
|
2699 | \&\f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to coexist peacefully with |
|
|
2700 | others). |
|
|
2701 | .PP |
|
|
2702 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
2703 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1583 | .IP "ev_prepare_init (ev_prepare *, callback)" 4 |
2704 | .IP "ev_prepare_init (ev_prepare *, callback)" 4 |
1584 | .IX Item "ev_prepare_init (ev_prepare *, callback)" |
2705 | .IX Item "ev_prepare_init (ev_prepare *, callback)" |
1585 | .PD 0 |
2706 | .PD 0 |
1586 | .IP "ev_check_init (ev_check *, callback)" 4 |
2707 | .IP "ev_check_init (ev_check *, callback)" 4 |
1587 | .IX Item "ev_check_init (ev_check *, callback)" |
2708 | .IX Item "ev_check_init (ev_check *, callback)" |
1588 | .PD |
2709 | .PD |
1589 | Initialises and configures the prepare or check watcher \- they have no |
2710 | Initialises and configures the prepare or check watcher \- they have no |
1590 | parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR |
2711 | parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR |
1591 | macros, but using them is utterly, utterly and completely pointless. |
2712 | macros, but using them is utterly, utterly, utterly and completely |
|
|
2713 | pointless. |
1592 | .PP |
2714 | .PP |
1593 | Example: To include a library such as adns, you would add \s-1IO\s0 watchers |
2715 | \fIExamples\fR |
1594 | and a timeout watcher in a prepare handler, as required by libadns, and |
2716 | .IX Subsection "Examples" |
|
|
2717 | .PP |
|
|
2718 | There are a number of principal ways to embed other event loops or modules |
|
|
2719 | into libev. Here are some ideas on how to include libadns into libev |
|
|
2720 | (there is a Perl module named \f(CW\*(C`EV::ADNS\*(C'\fR that does this, which you could |
|
|
2721 | use as a working example. Another Perl module named \f(CW\*(C`EV::Glib\*(C'\fR embeds a |
|
|
2722 | Glib main context into libev, and finally, \f(CW\*(C`Glib::EV\*(C'\fR embeds \s-1EV\s0 into the |
|
|
2723 | Glib event loop). |
|
|
2724 | .PP |
|
|
2725 | Method 1: Add \s-1IO\s0 watchers and a timeout watcher in a prepare handler, |
1595 | in a check watcher, destroy them and call into libadns. What follows is |
2726 | and in a check watcher, destroy them and call into libadns. What follows |
1596 | pseudo-code only of course: |
2727 | is pseudo-code only of course. This requires you to either use a low |
|
|
2728 | priority for the check watcher or use \f(CW\*(C`ev_clear_pending\*(C'\fR explicitly, as |
|
|
2729 | the callbacks for the IO/timeout watchers might not have been called yet. |
1597 | .PP |
2730 | .PP |
1598 | .Vb 2 |
2731 | .Vb 2 |
1599 | \& static ev_io iow [nfd]; |
2732 | \& static ev_io iow [nfd]; |
1600 | \& static ev_timer tw; |
2733 | \& static ev_timer tw; |
1601 | .Ve |
2734 | \& |
1602 | .PP |
|
|
1603 | .Vb 9 |
|
|
1604 | \& static void |
2735 | \& static void |
1605 | \& io_cb (ev_loop *loop, ev_io *w, int revents) |
2736 | \& io_cb (struct ev_loop *loop, ev_io *w, int revents) |
1606 | \& { |
2737 | \& { |
1607 | \& // set the relevant poll flags |
|
|
1608 | \& // could also call adns_processreadable etc. here |
|
|
1609 | \& struct pollfd *fd = (struct pollfd *)w->data; |
|
|
1610 | \& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1611 | \& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1612 | \& } |
2738 | \& } |
1613 | .Ve |
2739 | \& |
1614 | .PP |
|
|
1615 | .Vb 7 |
|
|
1616 | \& // create io watchers for each fd and a timer before blocking |
2740 | \& // create io watchers for each fd and a timer before blocking |
1617 | \& static void |
2741 | \& static void |
1618 | \& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
2742 | \& adns_prepare_cb (struct ev_loop *loop, ev_prepare *w, int revents) |
1619 | \& { |
2743 | \& { |
1620 | \& int timeout = 3600000;truct pollfd fds [nfd]; |
2744 | \& int timeout = 3600000; |
|
|
2745 | \& struct pollfd fds [nfd]; |
1621 | \& // actual code will need to loop here and realloc etc. |
2746 | \& // actual code will need to loop here and realloc etc. |
1622 | \& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
2747 | \& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1623 | .Ve |
2748 | \& |
1624 | .PP |
|
|
1625 | .Vb 3 |
|
|
1626 | \& /* the callback is illegal, but won't be called as we stop during check */ |
2749 | \& /* the callback is illegal, but won\*(Aqt be called as we stop during check */ |
1627 | \& ev_timer_init (&tw, 0, timeout * 1e-3); |
2750 | \& ev_timer_init (&tw, 0, timeout * 1e\-3, 0.); |
1628 | \& ev_timer_start (loop, &tw); |
2751 | \& ev_timer_start (loop, &tw); |
1629 | .Ve |
2752 | \& |
1630 | .PP |
|
|
1631 | .Vb 6 |
|
|
1632 | \& // create on ev_io per pollfd |
2753 | \& // create one ev_io per pollfd |
1633 | \& for (int i = 0; i < nfd; ++i) |
2754 | \& for (int i = 0; i < nfd; ++i) |
1634 | \& { |
2755 | \& { |
1635 | \& ev_io_init (iow + i, io_cb, fds [i].fd, |
2756 | \& ev_io_init (iow + i, io_cb, fds [i].fd, |
1636 | \& ((fds [i].events & POLLIN ? EV_READ : 0) |
2757 | \& ((fds [i].events & POLLIN ? EV_READ : 0) |
1637 | \& | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
2758 | \& | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
|
|
2759 | \& |
|
|
2760 | \& fds [i].revents = 0; |
|
|
2761 | \& ev_io_start (loop, iow + i); |
|
|
2762 | \& } |
|
|
2763 | \& } |
|
|
2764 | \& |
|
|
2765 | \& // stop all watchers after blocking |
|
|
2766 | \& static void |
|
|
2767 | \& adns_check_cb (struct ev_loop *loop, ev_check *w, int revents) |
|
|
2768 | \& { |
|
|
2769 | \& ev_timer_stop (loop, &tw); |
|
|
2770 | \& |
|
|
2771 | \& for (int i = 0; i < nfd; ++i) |
|
|
2772 | \& { |
|
|
2773 | \& // set the relevant poll flags |
|
|
2774 | \& // could also call adns_processreadable etc. here |
|
|
2775 | \& struct pollfd *fd = fds + i; |
|
|
2776 | \& int revents = ev_clear_pending (iow + i); |
|
|
2777 | \& if (revents & EV_READ ) fd\->revents |= fd\->events & POLLIN; |
|
|
2778 | \& if (revents & EV_WRITE) fd\->revents |= fd\->events & POLLOUT; |
|
|
2779 | \& |
|
|
2780 | \& // now stop the watcher |
|
|
2781 | \& ev_io_stop (loop, iow + i); |
|
|
2782 | \& } |
|
|
2783 | \& |
|
|
2784 | \& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
2785 | \& } |
1638 | .Ve |
2786 | .Ve |
|
|
2787 | .PP |
|
|
2788 | Method 2: This would be just like method 1, but you run \f(CW\*(C`adns_afterpoll\*(C'\fR |
|
|
2789 | in the prepare watcher and would dispose of the check watcher. |
|
|
2790 | .PP |
|
|
2791 | Method 3: If the module to be embedded supports explicit event |
|
|
2792 | notification (libadns does), you can also make use of the actual watcher |
|
|
2793 | callbacks, and only destroy/create the watchers in the prepare watcher. |
1639 | .PP |
2794 | .PP |
1640 | .Vb 5 |
2795 | .Vb 5 |
1641 | \& fds [i].revents = 0; |
|
|
1642 | \& iow [i].data = fds + i; |
|
|
1643 | \& ev_io_start (loop, iow + i); |
|
|
1644 | \& } |
|
|
1645 | \& } |
|
|
1646 | .Ve |
|
|
1647 | .PP |
|
|
1648 | .Vb 5 |
|
|
1649 | \& // stop all watchers after blocking |
|
|
1650 | \& static void |
2796 | \& static void |
1651 | \& adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
2797 | \& timer_cb (EV_P_ ev_timer *w, int revents) |
1652 | \& { |
2798 | \& { |
1653 | \& ev_timer_stop (loop, &tw); |
2799 | \& adns_state ads = (adns_state)w\->data; |
1654 | .Ve |
2800 | \& update_now (EV_A); |
1655 | .PP |
2801 | \& |
1656 | .Vb 2 |
2802 | \& adns_processtimeouts (ads, &tv_now); |
1657 | \& for (int i = 0; i < nfd; ++i) |
|
|
1658 | \& ev_io_stop (loop, iow + i); |
|
|
1659 | .Ve |
|
|
1660 | .PP |
|
|
1661 | .Vb 2 |
|
|
1662 | \& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
1663 | \& } |
2803 | \& } |
|
|
2804 | \& |
|
|
2805 | \& static void |
|
|
2806 | \& io_cb (EV_P_ ev_io *w, int revents) |
|
|
2807 | \& { |
|
|
2808 | \& adns_state ads = (adns_state)w\->data; |
|
|
2809 | \& update_now (EV_A); |
|
|
2810 | \& |
|
|
2811 | \& if (revents & EV_READ ) adns_processreadable (ads, w\->fd, &tv_now); |
|
|
2812 | \& if (revents & EV_WRITE) adns_processwriteable (ads, w\->fd, &tv_now); |
|
|
2813 | \& } |
|
|
2814 | \& |
|
|
2815 | \& // do not ever call adns_afterpoll |
1664 | .Ve |
2816 | .Ve |
|
|
2817 | .PP |
|
|
2818 | Method 4: Do not use a prepare or check watcher because the module you |
|
|
2819 | want to embed is not flexible enough to support it. Instead, you can |
|
|
2820 | override their poll function. The drawback with this solution is that the |
|
|
2821 | main loop is now no longer controllable by \s-1EV\s0. The \f(CW\*(C`Glib::EV\*(C'\fR module uses |
|
|
2822 | this approach, effectively embedding \s-1EV\s0 as a client into the horrible |
|
|
2823 | libglib event loop. |
|
|
2824 | .PP |
|
|
2825 | .Vb 4 |
|
|
2826 | \& static gint |
|
|
2827 | \& event_poll_func (GPollFD *fds, guint nfds, gint timeout) |
|
|
2828 | \& { |
|
|
2829 | \& int got_events = 0; |
|
|
2830 | \& |
|
|
2831 | \& for (n = 0; n < nfds; ++n) |
|
|
2832 | \& // create/start io watcher that sets the relevant bits in fds[n] and increment got_events |
|
|
2833 | \& |
|
|
2834 | \& if (timeout >= 0) |
|
|
2835 | \& // create/start timer |
|
|
2836 | \& |
|
|
2837 | \& // poll |
|
|
2838 | \& ev_loop (EV_A_ 0); |
|
|
2839 | \& |
|
|
2840 | \& // stop timer again |
|
|
2841 | \& if (timeout >= 0) |
|
|
2842 | \& ev_timer_stop (EV_A_ &to); |
|
|
2843 | \& |
|
|
2844 | \& // stop io watchers again \- their callbacks should have set |
|
|
2845 | \& for (n = 0; n < nfds; ++n) |
|
|
2846 | \& ev_io_stop (EV_A_ iow [n]); |
|
|
2847 | \& |
|
|
2848 | \& return got_events; |
|
|
2849 | \& } |
|
|
2850 | .Ve |
1665 | .ie n .Sh """ev_embed"" \- when one backend isn't enough..." |
2851 | .ie n .SS """ev_embed"" \- when one backend isn't enough..." |
1666 | .el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..." |
2852 | .el .SS "\f(CWev_embed\fP \- when one backend isn't enough..." |
1667 | .IX Subsection "ev_embed - when one backend isn't enough..." |
2853 | .IX Subsection "ev_embed - when one backend isn't enough..." |
1668 | This is a rather advanced watcher type that lets you embed one event loop |
2854 | This is a rather advanced watcher type that lets you embed one event loop |
1669 | into another (currently only \f(CW\*(C`ev_io\*(C'\fR events are supported in the embedded |
2855 | into another (currently only \f(CW\*(C`ev_io\*(C'\fR events are supported in the embedded |
1670 | loop, other types of watchers might be handled in a delayed or incorrect |
2856 | loop, other types of watchers might be handled in a delayed or incorrect |
1671 | fashion and must not be used). |
2857 | fashion and must not be used). |
… | |
… | |
1674 | prioritise I/O. |
2860 | prioritise I/O. |
1675 | .PP |
2861 | .PP |
1676 | As an example for a bug workaround, the kqueue backend might only support |
2862 | As an example for a bug workaround, the kqueue backend might only support |
1677 | sockets on some platform, so it is unusable as generic backend, but you |
2863 | sockets on some platform, so it is unusable as generic backend, but you |
1678 | still want to make use of it because you have many sockets and it scales |
2864 | still want to make use of it because you have many sockets and it scales |
1679 | so nicely. In this case, you would create a kqueue-based loop and embed it |
2865 | so nicely. In this case, you would create a kqueue-based loop and embed |
1680 | into your default loop (which might use e.g. poll). Overall operation will |
2866 | it into your default loop (which might use e.g. poll). Overall operation |
1681 | be a bit slower because first libev has to poll and then call kevent, but |
2867 | will be a bit slower because first libev has to call \f(CW\*(C`poll\*(C'\fR and then |
1682 | at least you can use both at what they are best. |
2868 | \&\f(CW\*(C`kevent\*(C'\fR, but at least you can use both mechanisms for what they are |
|
|
2869 | best: \f(CW\*(C`kqueue\*(C'\fR for scalable sockets and \f(CW\*(C`poll\*(C'\fR if you want it to work :) |
1683 | .PP |
2870 | .PP |
1684 | As for prioritising I/O: rarely you have the case where some fds have |
2871 | As for prioritising I/O: under rare circumstances you have the case where |
1685 | to be watched and handled very quickly (with low latency), and even |
2872 | some fds have to be watched and handled very quickly (with low latency), |
1686 | priorities and idle watchers might have too much overhead. In this case |
2873 | and even priorities and idle watchers might have too much overhead. In |
1687 | you would put all the high priority stuff in one loop and all the rest in |
2874 | this case you would put all the high priority stuff in one loop and all |
1688 | a second one, and embed the second one in the first. |
2875 | the rest in a second one, and embed the second one in the first. |
1689 | .PP |
2876 | .PP |
1690 | As long as the watcher is active, the callback will be invoked every time |
2877 | As long as the watcher is active, the callback will be invoked every |
1691 | there might be events pending in the embedded loop. The callback must then |
2878 | time there might be events pending in the embedded loop. The callback |
1692 | call \f(CW\*(C`ev_embed_sweep (mainloop, watcher)\*(C'\fR to make a single sweep and invoke |
2879 | must then call \f(CW\*(C`ev_embed_sweep (mainloop, watcher)\*(C'\fR to make a single |
1693 | their callbacks (you could also start an idle watcher to give the embedded |
2880 | sweep and invoke their callbacks (the callback doesn't need to invoke the |
1694 | loop strictly lower priority for example). You can also set the callback |
2881 | \&\f(CW\*(C`ev_embed_sweep\*(C'\fR function directly, it could also start an idle watcher |
1695 | to \f(CW0\fR, in which case the embed watcher will automatically execute the |
2882 | to give the embedded loop strictly lower priority for example). |
1696 | embedded loop sweep. |
|
|
1697 | .PP |
2883 | .PP |
1698 | As long as the watcher is started it will automatically handle events. The |
2884 | You can also set the callback to \f(CW0\fR, in which case the embed watcher |
1699 | callback will be invoked whenever some events have been handled. You can |
2885 | will automatically execute the embedded loop sweep whenever necessary. |
1700 | set the callback to \f(CW0\fR to avoid having to specify one if you are not |
|
|
1701 | interested in that. |
|
|
1702 | .PP |
2886 | .PP |
1703 | Also, there have not currently been made special provisions for forking: |
2887 | Fork detection will be handled transparently while the \f(CW\*(C`ev_embed\*(C'\fR watcher |
1704 | when you fork, you not only have to call \f(CW\*(C`ev_loop_fork\*(C'\fR on both loops, |
2888 | is active, i.e., the embedded loop will automatically be forked when the |
1705 | but you will also have to stop and restart any \f(CW\*(C`ev_embed\*(C'\fR watchers |
2889 | embedding loop forks. In other cases, the user is responsible for calling |
1706 | yourself. |
2890 | \&\f(CW\*(C`ev_loop_fork\*(C'\fR on the embedded loop. |
1707 | .PP |
2891 | .PP |
1708 | Unfortunately, not all backends are embeddable, only the ones returned by |
2892 | Unfortunately, not all backends are embeddable: only the ones returned by |
1709 | \&\f(CW\*(C`ev_embeddable_backends\*(C'\fR are, which, unfortunately, does not include any |
2893 | \&\f(CW\*(C`ev_embeddable_backends\*(C'\fR are, which, unfortunately, does not include any |
1710 | portable one. |
2894 | portable one. |
1711 | .PP |
2895 | .PP |
1712 | So when you want to use this feature you will always have to be prepared |
2896 | So when you want to use this feature you will always have to be prepared |
1713 | that you cannot get an embeddable loop. The recommended way to get around |
2897 | that you cannot get an embeddable loop. The recommended way to get around |
1714 | this is to have a separate variables for your embeddable loop, try to |
2898 | this is to have a separate variables for your embeddable loop, try to |
1715 | create it, and if that fails, use the normal loop for everything: |
2899 | create it, and if that fails, use the normal loop for everything. |
1716 | .PP |
2900 | .PP |
1717 | .Vb 3 |
2901 | \fI\f(CI\*(C`ev_embed\*(C'\fI and fork\fR |
1718 | \& struct ev_loop *loop_hi = ev_default_init (0); |
2902 | .IX Subsection "ev_embed and fork" |
1719 | \& struct ev_loop *loop_lo = 0; |
|
|
1720 | \& struct ev_embed embed; |
|
|
1721 | .Ve |
|
|
1722 | .PP |
2903 | .PP |
1723 | .Vb 5 |
2904 | While the \f(CW\*(C`ev_embed\*(C'\fR watcher is running, forks in the embedding loop will |
1724 | \& // see if there is a chance of getting one that works |
2905 | automatically be applied to the embedded loop as well, so no special |
1725 | \& // (remember that a flags value of 0 means autodetection) |
2906 | fork handling is required in that case. When the watcher is not running, |
1726 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
2907 | however, it is still the task of the libev user to call \f(CW\*(C`ev_loop_fork ()\*(C'\fR |
1727 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
2908 | as applicable. |
1728 | \& : 0; |
|
|
1729 | .Ve |
|
|
1730 | .PP |
2909 | .PP |
1731 | .Vb 8 |
2910 | \fIWatcher-Specific Functions and Data Members\fR |
1732 | \& // if we got one, then embed it, otherwise default to loop_hi |
2911 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1733 | \& if (loop_lo) |
|
|
1734 | \& { |
|
|
1735 | \& ev_embed_init (&embed, 0, loop_lo); |
|
|
1736 | \& ev_embed_start (loop_hi, &embed); |
|
|
1737 | \& } |
|
|
1738 | \& else |
|
|
1739 | \& loop_lo = loop_hi; |
|
|
1740 | .Ve |
|
|
1741 | .IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
2912 | .IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
1742 | .IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" |
2913 | .IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" |
1743 | .PD 0 |
2914 | .PD 0 |
1744 | .IP "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
2915 | .IP "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
1745 | .IX Item "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" |
2916 | .IX Item "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" |
1746 | .PD |
2917 | .PD |
1747 | Configures the watcher to embed the given loop, which must be |
2918 | Configures the watcher to embed the given loop, which must be |
1748 | embeddable. If the callback is \f(CW0\fR, then \f(CW\*(C`ev_embed_sweep\*(C'\fR will be |
2919 | embeddable. If the callback is \f(CW0\fR, then \f(CW\*(C`ev_embed_sweep\*(C'\fR will be |
1749 | invoked automatically, otherwise it is the responsibility of the callback |
2920 | invoked automatically, otherwise it is the responsibility of the callback |
1750 | to invoke it (it will continue to be called until the sweep has been done, |
2921 | to invoke it (it will continue to be called until the sweep has been done, |
1751 | if you do not want thta, you need to temporarily stop the embed watcher). |
2922 | if you do not want that, you need to temporarily stop the embed watcher). |
1752 | .IP "ev_embed_sweep (loop, ev_embed *)" 4 |
2923 | .IP "ev_embed_sweep (loop, ev_embed *)" 4 |
1753 | .IX Item "ev_embed_sweep (loop, ev_embed *)" |
2924 | .IX Item "ev_embed_sweep (loop, ev_embed *)" |
1754 | Make a single, non-blocking sweep over the embedded loop. This works |
2925 | Make a single, non-blocking sweep over the embedded loop. This works |
1755 | similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most |
2926 | similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most |
1756 | apropriate way for embedded loops. |
2927 | appropriate way for embedded loops. |
1757 | .IP "struct ev_loop *loop [read\-only]" 4 |
2928 | .IP "struct ev_loop *other [read\-only]" 4 |
1758 | .IX Item "struct ev_loop *loop [read-only]" |
2929 | .IX Item "struct ev_loop *other [read-only]" |
1759 | The embedded event loop. |
2930 | The embedded event loop. |
|
|
2931 | .PP |
|
|
2932 | \fIExamples\fR |
|
|
2933 | .IX Subsection "Examples" |
|
|
2934 | .PP |
|
|
2935 | Example: Try to get an embeddable event loop and embed it into the default |
|
|
2936 | event loop. If that is not possible, use the default loop. The default |
|
|
2937 | loop is stored in \f(CW\*(C`loop_hi\*(C'\fR, while the embeddable loop is stored in |
|
|
2938 | \&\f(CW\*(C`loop_lo\*(C'\fR (which is \f(CW\*(C`loop_hi\*(C'\fR in the case no embeddable loop can be |
|
|
2939 | used). |
|
|
2940 | .PP |
|
|
2941 | .Vb 3 |
|
|
2942 | \& struct ev_loop *loop_hi = ev_default_init (0); |
|
|
2943 | \& struct ev_loop *loop_lo = 0; |
|
|
2944 | \& ev_embed embed; |
|
|
2945 | \& |
|
|
2946 | \& // see if there is a chance of getting one that works |
|
|
2947 | \& // (remember that a flags value of 0 means autodetection) |
|
|
2948 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
|
|
2949 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
|
|
2950 | \& : 0; |
|
|
2951 | \& |
|
|
2952 | \& // if we got one, then embed it, otherwise default to loop_hi |
|
|
2953 | \& if (loop_lo) |
|
|
2954 | \& { |
|
|
2955 | \& ev_embed_init (&embed, 0, loop_lo); |
|
|
2956 | \& ev_embed_start (loop_hi, &embed); |
|
|
2957 | \& } |
|
|
2958 | \& else |
|
|
2959 | \& loop_lo = loop_hi; |
|
|
2960 | .Ve |
|
|
2961 | .PP |
|
|
2962 | Example: Check if kqueue is available but not recommended and create |
|
|
2963 | a kqueue backend for use with sockets (which usually work with any |
|
|
2964 | kqueue implementation). Store the kqueue/socket\-only event loop in |
|
|
2965 | \&\f(CW\*(C`loop_socket\*(C'\fR. (One might optionally use \f(CW\*(C`EVFLAG_NOENV\*(C'\fR, too). |
|
|
2966 | .PP |
|
|
2967 | .Vb 3 |
|
|
2968 | \& struct ev_loop *loop = ev_default_init (0); |
|
|
2969 | \& struct ev_loop *loop_socket = 0; |
|
|
2970 | \& ev_embed embed; |
|
|
2971 | \& |
|
|
2972 | \& if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
|
|
2973 | \& if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
|
|
2974 | \& { |
|
|
2975 | \& ev_embed_init (&embed, 0, loop_socket); |
|
|
2976 | \& ev_embed_start (loop, &embed); |
|
|
2977 | \& } |
|
|
2978 | \& |
|
|
2979 | \& if (!loop_socket) |
|
|
2980 | \& loop_socket = loop; |
|
|
2981 | \& |
|
|
2982 | \& // now use loop_socket for all sockets, and loop for everything else |
|
|
2983 | .Ve |
1760 | .ie n .Sh """ev_fork"" \- the audacity to resume the event loop after a fork" |
2984 | .ie n .SS """ev_fork"" \- the audacity to resume the event loop after a fork" |
1761 | .el .Sh "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
2985 | .el .SS "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
1762 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
2986 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
1763 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
2987 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
1764 | whoever is a good citizen cared to tell libev about it by calling |
2988 | whoever is a good citizen cared to tell libev about it by calling |
1765 | \&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the |
2989 | \&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the |
1766 | event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, |
2990 | event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, |
1767 | and only in the child after the fork. If whoever good citizen calling |
2991 | and only in the child after the fork. If whoever good citizen calling |
1768 | \&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork |
2992 | \&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork |
1769 | handlers will be invoked, too, of course. |
2993 | handlers will be invoked, too, of course. |
|
|
2994 | .PP |
|
|
2995 | \fIThe special problem of life after fork \- how is it possible?\fR |
|
|
2996 | .IX Subsection "The special problem of life after fork - how is it possible?" |
|
|
2997 | .PP |
|
|
2998 | Most uses of \f(CW\*(C`fork()\*(C'\fR consist of forking, then some simple calls to ste |
|
|
2999 | up/change the process environment, followed by a call to \f(CW\*(C`exec()\*(C'\fR. This |
|
|
3000 | sequence should be handled by libev without any problems. |
|
|
3001 | .PP |
|
|
3002 | This changes when the application actually wants to do event handling |
|
|
3003 | in the child, or both parent in child, in effect \*(L"continuing\*(R" after the |
|
|
3004 | fork. |
|
|
3005 | .PP |
|
|
3006 | The default mode of operation (for libev, with application help to detect |
|
|
3007 | forks) is to duplicate all the state in the child, as would be expected |
|
|
3008 | when \fIeither\fR the parent \fIor\fR the child process continues. |
|
|
3009 | .PP |
|
|
3010 | When both processes want to continue using libev, then this is usually the |
|
|
3011 | wrong result. In that case, usually one process (typically the parent) is |
|
|
3012 | supposed to continue with all watchers in place as before, while the other |
|
|
3013 | process typically wants to start fresh, i.e. without any active watchers. |
|
|
3014 | .PP |
|
|
3015 | The cleanest and most efficient way to achieve that with libev is to |
|
|
3016 | simply create a new event loop, which of course will be \*(L"empty\*(R", and |
|
|
3017 | use that for new watchers. This has the advantage of not touching more |
|
|
3018 | memory than necessary, and thus avoiding the copy-on-write, and the |
|
|
3019 | disadvantage of having to use multiple event loops (which do not support |
|
|
3020 | signal watchers). |
|
|
3021 | .PP |
|
|
3022 | When this is not possible, or you want to use the default loop for |
|
|
3023 | other reasons, then in the process that wants to start \*(L"fresh\*(R", call |
|
|
3024 | \&\f(CW\*(C`ev_default_destroy ()\*(C'\fR followed by \f(CW\*(C`ev_default_loop (...)\*(C'\fR. Destroying |
|
|
3025 | the default loop will \*(L"orphan\*(R" (not stop) all registered watchers, so you |
|
|
3026 | have to be careful not to execute code that modifies those watchers. Note |
|
|
3027 | also that in that case, you have to re-register any signal watchers. |
|
|
3028 | .PP |
|
|
3029 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
3030 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1770 | .IP "ev_fork_init (ev_signal *, callback)" 4 |
3031 | .IP "ev_fork_init (ev_signal *, callback)" 4 |
1771 | .IX Item "ev_fork_init (ev_signal *, callback)" |
3032 | .IX Item "ev_fork_init (ev_signal *, callback)" |
1772 | Initialises and configures the fork watcher \- it has no parameters of any |
3033 | Initialises and configures the fork watcher \- it has no parameters of any |
1773 | kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless, |
3034 | kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless, |
1774 | believe me. |
3035 | believe me. |
|
|
3036 | .ie n .SS """ev_async"" \- how to wake up another event loop" |
|
|
3037 | .el .SS "\f(CWev_async\fP \- how to wake up another event loop" |
|
|
3038 | .IX Subsection "ev_async - how to wake up another event loop" |
|
|
3039 | In general, you cannot use an \f(CW\*(C`ev_loop\*(C'\fR from multiple threads or other |
|
|
3040 | asynchronous sources such as signal handlers (as opposed to multiple event |
|
|
3041 | loops \- those are of course safe to use in different threads). |
|
|
3042 | .PP |
|
|
3043 | Sometimes, however, you need to wake up another event loop you do not |
|
|
3044 | control, for example because it belongs to another thread. This is what |
|
|
3045 | \&\f(CW\*(C`ev_async\*(C'\fR watchers do: as long as the \f(CW\*(C`ev_async\*(C'\fR watcher is active, you |
|
|
3046 | can signal it by calling \f(CW\*(C`ev_async_send\*(C'\fR, which is thread\- and signal |
|
|
3047 | safe. |
|
|
3048 | .PP |
|
|
3049 | This functionality is very similar to \f(CW\*(C`ev_signal\*(C'\fR watchers, as signals, |
|
|
3050 | too, are asynchronous in nature, and signals, too, will be compressed |
|
|
3051 | (i.e. the number of callback invocations may be less than the number of |
|
|
3052 | \&\f(CW\*(C`ev_async_sent\*(C'\fR calls). |
|
|
3053 | .PP |
|
|
3054 | Unlike \f(CW\*(C`ev_signal\*(C'\fR watchers, \f(CW\*(C`ev_async\*(C'\fR works with any event loop, not |
|
|
3055 | just the default loop. |
|
|
3056 | .PP |
|
|
3057 | \fIQueueing\fR |
|
|
3058 | .IX Subsection "Queueing" |
|
|
3059 | .PP |
|
|
3060 | \&\f(CW\*(C`ev_async\*(C'\fR does not support queueing of data in any way. The reason |
|
|
3061 | is that the author does not know of a simple (or any) algorithm for a |
|
|
3062 | multiple-writer-single-reader queue that works in all cases and doesn't |
|
|
3063 | need elaborate support such as pthreads. |
|
|
3064 | .PP |
|
|
3065 | That means that if you want to queue data, you have to provide your own |
|
|
3066 | queue. But at least I can tell you how to implement locking around your |
|
|
3067 | queue: |
|
|
3068 | .IP "queueing from a signal handler context" 4 |
|
|
3069 | .IX Item "queueing from a signal handler context" |
|
|
3070 | To implement race-free queueing, you simply add to the queue in the signal |
|
|
3071 | handler but you block the signal handler in the watcher callback. Here is |
|
|
3072 | an example that does that for some fictitious \s-1SIGUSR1\s0 handler: |
|
|
3073 | .Sp |
|
|
3074 | .Vb 1 |
|
|
3075 | \& static ev_async mysig; |
|
|
3076 | \& |
|
|
3077 | \& static void |
|
|
3078 | \& sigusr1_handler (void) |
|
|
3079 | \& { |
|
|
3080 | \& sometype data; |
|
|
3081 | \& |
|
|
3082 | \& // no locking etc. |
|
|
3083 | \& queue_put (data); |
|
|
3084 | \& ev_async_send (EV_DEFAULT_ &mysig); |
|
|
3085 | \& } |
|
|
3086 | \& |
|
|
3087 | \& static void |
|
|
3088 | \& mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
3089 | \& { |
|
|
3090 | \& sometype data; |
|
|
3091 | \& sigset_t block, prev; |
|
|
3092 | \& |
|
|
3093 | \& sigemptyset (&block); |
|
|
3094 | \& sigaddset (&block, SIGUSR1); |
|
|
3095 | \& sigprocmask (SIG_BLOCK, &block, &prev); |
|
|
3096 | \& |
|
|
3097 | \& while (queue_get (&data)) |
|
|
3098 | \& process (data); |
|
|
3099 | \& |
|
|
3100 | \& if (sigismember (&prev, SIGUSR1) |
|
|
3101 | \& sigprocmask (SIG_UNBLOCK, &block, 0); |
|
|
3102 | \& } |
|
|
3103 | .Ve |
|
|
3104 | .Sp |
|
|
3105 | (Note: pthreads in theory requires you to use \f(CW\*(C`pthread_setmask\*(C'\fR |
|
|
3106 | instead of \f(CW\*(C`sigprocmask\*(C'\fR when you use threads, but libev doesn't do it |
|
|
3107 | either...). |
|
|
3108 | .IP "queueing from a thread context" 4 |
|
|
3109 | .IX Item "queueing from a thread context" |
|
|
3110 | The strategy for threads is different, as you cannot (easily) block |
|
|
3111 | threads but you can easily preempt them, so to queue safely you need to |
|
|
3112 | employ a traditional mutex lock, such as in this pthread example: |
|
|
3113 | .Sp |
|
|
3114 | .Vb 2 |
|
|
3115 | \& static ev_async mysig; |
|
|
3116 | \& static pthread_mutex_t mymutex = PTHREAD_MUTEX_INITIALIZER; |
|
|
3117 | \& |
|
|
3118 | \& static void |
|
|
3119 | \& otherthread (void) |
|
|
3120 | \& { |
|
|
3121 | \& // only need to lock the actual queueing operation |
|
|
3122 | \& pthread_mutex_lock (&mymutex); |
|
|
3123 | \& queue_put (data); |
|
|
3124 | \& pthread_mutex_unlock (&mymutex); |
|
|
3125 | \& |
|
|
3126 | \& ev_async_send (EV_DEFAULT_ &mysig); |
|
|
3127 | \& } |
|
|
3128 | \& |
|
|
3129 | \& static void |
|
|
3130 | \& mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
3131 | \& { |
|
|
3132 | \& pthread_mutex_lock (&mymutex); |
|
|
3133 | \& |
|
|
3134 | \& while (queue_get (&data)) |
|
|
3135 | \& process (data); |
|
|
3136 | \& |
|
|
3137 | \& pthread_mutex_unlock (&mymutex); |
|
|
3138 | \& } |
|
|
3139 | .Ve |
|
|
3140 | .PP |
|
|
3141 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
3142 | .IX Subsection "Watcher-Specific Functions and Data Members" |
|
|
3143 | .IP "ev_async_init (ev_async *, callback)" 4 |
|
|
3144 | .IX Item "ev_async_init (ev_async *, callback)" |
|
|
3145 | Initialises and configures the async watcher \- it has no parameters of any |
|
|
3146 | kind. There is a \f(CW\*(C`ev_async_set\*(C'\fR macro, but using it is utterly pointless, |
|
|
3147 | trust me. |
|
|
3148 | .IP "ev_async_send (loop, ev_async *)" 4 |
|
|
3149 | .IX Item "ev_async_send (loop, ev_async *)" |
|
|
3150 | Sends/signals/activates the given \f(CW\*(C`ev_async\*(C'\fR watcher, that is, feeds |
|
|
3151 | an \f(CW\*(C`EV_ASYNC\*(C'\fR event on the watcher into the event loop. Unlike |
|
|
3152 | \&\f(CW\*(C`ev_feed_event\*(C'\fR, this call is safe to do from other threads, signal or |
|
|
3153 | similar contexts (see the discussion of \f(CW\*(C`EV_ATOMIC_T\*(C'\fR in the embedding |
|
|
3154 | section below on what exactly this means). |
|
|
3155 | .Sp |
|
|
3156 | Note that, as with other watchers in libev, multiple events might get |
|
|
3157 | compressed into a single callback invocation (another way to look at this |
|
|
3158 | is that \f(CW\*(C`ev_async\*(C'\fR watchers are level-triggered, set on \f(CW\*(C`ev_async_send\*(C'\fR, |
|
|
3159 | reset when the event loop detects that). |
|
|
3160 | .Sp |
|
|
3161 | This call incurs the overhead of a system call only once per event loop |
|
|
3162 | iteration, so while the overhead might be noticeable, it doesn't apply to |
|
|
3163 | repeated calls to \f(CW\*(C`ev_async_send\*(C'\fR for the same event loop. |
|
|
3164 | .IP "bool = ev_async_pending (ev_async *)" 4 |
|
|
3165 | .IX Item "bool = ev_async_pending (ev_async *)" |
|
|
3166 | Returns a non-zero value when \f(CW\*(C`ev_async_send\*(C'\fR has been called on the |
|
|
3167 | watcher but the event has not yet been processed (or even noted) by the |
|
|
3168 | event loop. |
|
|
3169 | .Sp |
|
|
3170 | \&\f(CW\*(C`ev_async_send\*(C'\fR sets a flag in the watcher and wakes up the loop. When |
|
|
3171 | the loop iterates next and checks for the watcher to have become active, |
|
|
3172 | it will reset the flag again. \f(CW\*(C`ev_async_pending\*(C'\fR can be used to very |
|
|
3173 | quickly check whether invoking the loop might be a good idea. |
|
|
3174 | .Sp |
|
|
3175 | Not that this does \fInot\fR check whether the watcher itself is pending, |
|
|
3176 | only whether it has been requested to make this watcher pending: there |
|
|
3177 | is a time window between the event loop checking and resetting the async |
|
|
3178 | notification, and the callback being invoked. |
1775 | .SH "OTHER FUNCTIONS" |
3179 | .SH "OTHER FUNCTIONS" |
1776 | .IX Header "OTHER FUNCTIONS" |
3180 | .IX Header "OTHER FUNCTIONS" |
1777 | There are some other functions of possible interest. Described. Here. Now. |
3181 | There are some other functions of possible interest. Described. Here. Now. |
1778 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 |
3182 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 |
1779 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" |
3183 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" |
1780 | This function combines a simple timer and an I/O watcher, calls your |
3184 | This function combines a simple timer and an I/O watcher, calls your |
1781 | callback on whichever event happens first and automatically stop both |
3185 | callback on whichever event happens first and automatically stops both |
1782 | watchers. This is useful if you want to wait for a single event on an fd |
3186 | watchers. This is useful if you want to wait for a single event on an fd |
1783 | or timeout without having to allocate/configure/start/stop/free one or |
3187 | or timeout without having to allocate/configure/start/stop/free one or |
1784 | more watchers yourself. |
3188 | more watchers yourself. |
1785 | .Sp |
3189 | .Sp |
1786 | If \f(CW\*(C`fd\*(C'\fR is less than 0, then no I/O watcher will be started and events |
3190 | If \f(CW\*(C`fd\*(C'\fR is less than 0, then no I/O watcher will be started and the |
1787 | is being ignored. Otherwise, an \f(CW\*(C`ev_io\*(C'\fR watcher for the given \f(CW\*(C`fd\*(C'\fR and |
3191 | \&\f(CW\*(C`events\*(C'\fR argument is being ignored. Otherwise, an \f(CW\*(C`ev_io\*(C'\fR watcher for |
1788 | \&\f(CW\*(C`events\*(C'\fR set will be craeted and started. |
3192 | the given \f(CW\*(C`fd\*(C'\fR and \f(CW\*(C`events\*(C'\fR set will be created and started. |
1789 | .Sp |
3193 | .Sp |
1790 | If \f(CW\*(C`timeout\*(C'\fR is less than 0, then no timeout watcher will be |
3194 | If \f(CW\*(C`timeout\*(C'\fR is less than 0, then no timeout watcher will be |
1791 | started. Otherwise an \f(CW\*(C`ev_timer\*(C'\fR watcher with after = \f(CW\*(C`timeout\*(C'\fR (and |
3195 | started. Otherwise an \f(CW\*(C`ev_timer\*(C'\fR watcher with after = \f(CW\*(C`timeout\*(C'\fR (and |
1792 | repeat = 0) will be started. While \f(CW0\fR is a valid timeout, it is of |
3196 | repeat = 0) will be started. \f(CW0\fR is a valid timeout. |
1793 | dubious value. |
|
|
1794 | .Sp |
3197 | .Sp |
1795 | The callback has the type \f(CW\*(C`void (*cb)(int revents, void *arg)\*(C'\fR and gets |
3198 | The callback has the type \f(CW\*(C`void (*cb)(int revents, void *arg)\*(C'\fR and gets |
1796 | passed an \f(CW\*(C`revents\*(C'\fR set like normal event callbacks (a combination of |
3199 | passed an \f(CW\*(C`revents\*(C'\fR set like normal event callbacks (a combination of |
1797 | \&\f(CW\*(C`EV_ERROR\*(C'\fR, \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or \f(CW\*(C`EV_TIMEOUT\*(C'\fR) and the \f(CW\*(C`arg\*(C'\fR |
3200 | \&\f(CW\*(C`EV_ERROR\*(C'\fR, \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or \f(CW\*(C`EV_TIMEOUT\*(C'\fR) and the \f(CW\*(C`arg\*(C'\fR |
1798 | value passed to \f(CW\*(C`ev_once\*(C'\fR: |
3201 | value passed to \f(CW\*(C`ev_once\*(C'\fR. Note that it is possible to receive \fIboth\fR |
|
|
3202 | a timeout and an io event at the same time \- you probably should give io |
|
|
3203 | events precedence. |
|
|
3204 | .Sp |
|
|
3205 | Example: wait up to ten seconds for data to appear on \s-1STDIN_FILENO\s0. |
1799 | .Sp |
3206 | .Sp |
1800 | .Vb 7 |
3207 | .Vb 7 |
1801 | \& static void stdin_ready (int revents, void *arg) |
3208 | \& static void stdin_ready (int revents, void *arg) |
1802 | \& { |
3209 | \& { |
1803 | \& if (revents & EV_TIMEOUT) |
|
|
1804 | \& /* doh, nothing entered */; |
|
|
1805 | \& else if (revents & EV_READ) |
3210 | \& if (revents & EV_READ) |
1806 | \& /* stdin might have data for us, joy! */; |
3211 | \& /* stdin might have data for us, joy! */; |
|
|
3212 | \& else if (revents & EV_TIMEOUT) |
|
|
3213 | \& /* doh, nothing entered */; |
1807 | \& } |
3214 | \& } |
1808 | .Ve |
3215 | \& |
1809 | .Sp |
|
|
1810 | .Vb 1 |
|
|
1811 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3216 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
1812 | .Ve |
3217 | .Ve |
1813 | .IP "ev_feed_event (ev_loop *, watcher *, int revents)" 4 |
3218 | .IP "ev_feed_event (struct ev_loop *, watcher *, int revents)" 4 |
1814 | .IX Item "ev_feed_event (ev_loop *, watcher *, int revents)" |
3219 | .IX Item "ev_feed_event (struct ev_loop *, watcher *, int revents)" |
1815 | Feeds the given event set into the event loop, as if the specified event |
3220 | Feeds the given event set into the event loop, as if the specified event |
1816 | had happened for the specified watcher (which must be a pointer to an |
3221 | had happened for the specified watcher (which must be a pointer to an |
1817 | initialised but not necessarily started event watcher). |
3222 | initialised but not necessarily started event watcher). |
1818 | .IP "ev_feed_fd_event (ev_loop *, int fd, int revents)" 4 |
3223 | .IP "ev_feed_fd_event (struct ev_loop *, int fd, int revents)" 4 |
1819 | .IX Item "ev_feed_fd_event (ev_loop *, int fd, int revents)" |
3224 | .IX Item "ev_feed_fd_event (struct ev_loop *, int fd, int revents)" |
1820 | Feed an event on the given fd, as if a file descriptor backend detected |
3225 | Feed an event on the given fd, as if a file descriptor backend detected |
1821 | the given events it. |
3226 | the given events it. |
1822 | .IP "ev_feed_signal_event (ev_loop *loop, int signum)" 4 |
3227 | .IP "ev_feed_signal_event (struct ev_loop *loop, int signum)" 4 |
1823 | .IX Item "ev_feed_signal_event (ev_loop *loop, int signum)" |
3228 | .IX Item "ev_feed_signal_event (struct ev_loop *loop, int signum)" |
1824 | Feed an event as if the given signal occured (\f(CW\*(C`loop\*(C'\fR must be the default |
3229 | Feed an event as if the given signal occurred (\f(CW\*(C`loop\*(C'\fR must be the default |
1825 | loop!). |
3230 | loop!). |
1826 | .SH "LIBEVENT EMULATION" |
3231 | .SH "LIBEVENT EMULATION" |
1827 | .IX Header "LIBEVENT EMULATION" |
3232 | .IX Header "LIBEVENT EMULATION" |
1828 | Libev offers a compatibility emulation layer for libevent. It cannot |
3233 | Libev offers a compatibility emulation layer for libevent. It cannot |
1829 | emulate the internals of libevent, so here are some usage hints: |
3234 | emulate the internals of libevent, so here are some usage hints: |
|
|
3235 | .IP "\(bu" 4 |
1830 | .IP "* Use it by including <event.h>, as usual." 4 |
3236 | Use it by including <event.h>, as usual. |
1831 | .IX Item "Use it by including <event.h>, as usual." |
3237 | .IP "\(bu" 4 |
1832 | .PD 0 |
3238 | The following members are fully supported: ev_base, ev_callback, |
1833 | .IP "* The following members are fully supported: ev_base, ev_callback, ev_arg, ev_fd, ev_res, ev_events." 4 |
3239 | ev_arg, ev_fd, ev_res, ev_events. |
1834 | .IX Item "The following members are fully supported: ev_base, ev_callback, ev_arg, ev_fd, ev_res, ev_events." |
3240 | .IP "\(bu" 4 |
1835 | .IP "* Avoid using ev_flags and the EVLIST_*\-macros, while it is maintained by libev, it does not work exactly the same way as in libevent (consider it a private \s-1API\s0)." 4 |
3241 | Avoid using ev_flags and the EVLIST_*\-macros, while it is |
1836 | .IX Item "Avoid using ev_flags and the EVLIST_*-macros, while it is maintained by libev, it does not work exactly the same way as in libevent (consider it a private API)." |
3242 | maintained by libev, it does not work exactly the same way as in libevent (consider |
1837 | .IP "* Priorities are not currently supported. Initialising priorities will fail and all watchers will have the same priority, even though there is an ev_pri field." 4 |
3243 | it a private \s-1API\s0). |
1838 | .IX Item "Priorities are not currently supported. Initialising priorities will fail and all watchers will have the same priority, even though there is an ev_pri field." |
3244 | .IP "\(bu" 4 |
|
|
3245 | Priorities are not currently supported. Initialising priorities |
|
|
3246 | will fail and all watchers will have the same priority, even though there |
|
|
3247 | is an ev_pri field. |
|
|
3248 | .IP "\(bu" 4 |
|
|
3249 | In libevent, the last base created gets the signals, in libev, the |
|
|
3250 | first base created (== the default loop) gets the signals. |
|
|
3251 | .IP "\(bu" 4 |
1839 | .IP "* Other members are not supported." 4 |
3252 | Other members are not supported. |
1840 | .IX Item "Other members are not supported." |
3253 | .IP "\(bu" 4 |
1841 | .IP "* The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need to use the libev header file and library." 4 |
3254 | The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need |
1842 | .IX Item "The libev emulation is not ABI compatible to libevent, you need to use the libev header file and library." |
3255 | to use the libev header file and library. |
1843 | .PD |
|
|
1844 | .SH "\*(C+ SUPPORT" |
3256 | .SH "\*(C+ SUPPORT" |
1845 | .IX Header " SUPPORT" |
3257 | .IX Header " SUPPORT" |
1846 | Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow |
3258 | Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow |
1847 | you to use some convinience methods to start/stop watchers and also change |
3259 | you to use some convenience methods to start/stop watchers and also change |
1848 | the callback model to a model using method callbacks on objects. |
3260 | the callback model to a model using method callbacks on objects. |
1849 | .PP |
3261 | .PP |
1850 | To use it, |
3262 | To use it, |
1851 | .PP |
3263 | .PP |
1852 | .Vb 1 |
3264 | .Vb 1 |
1853 | \& #include <ev++.h> |
3265 | \& #include <ev++.h> |
1854 | .Ve |
3266 | .Ve |
1855 | .PP |
3267 | .PP |
1856 | (it is not installed by default). This automatically includes \fIev.h\fR |
3268 | This automatically includes \fIev.h\fR and puts all of its definitions (many |
1857 | and puts all of its definitions (many of them macros) into the global |
3269 | of them macros) into the global namespace. All \*(C+ specific things are |
1858 | namespace. All \*(C+ specific things are put into the \f(CW\*(C`ev\*(C'\fR namespace. |
3270 | put into the \f(CW\*(C`ev\*(C'\fR namespace. It should support all the same embedding |
|
|
3271 | options as \fIev.h\fR, most notably \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. |
1859 | .PP |
3272 | .PP |
1860 | It should support all the same embedding options as \fIev.h\fR, most notably |
3273 | Care has been taken to keep the overhead low. The only data member the \*(C+ |
1861 | \&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. |
3274 | classes add (compared to plain C\-style watchers) is the event loop pointer |
|
|
3275 | that the watcher is associated with (or no additional members at all if |
|
|
3276 | you disable \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR when embedding libev). |
|
|
3277 | .PP |
|
|
3278 | Currently, functions, and static and non-static member functions can be |
|
|
3279 | used as callbacks. Other types should be easy to add as long as they only |
|
|
3280 | need one additional pointer for context. If you need support for other |
|
|
3281 | types of functors please contact the author (preferably after implementing |
|
|
3282 | it). |
1862 | .PP |
3283 | .PP |
1863 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
3284 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
1864 | .ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4 |
3285 | .ie n .IP """ev::READ"", ""ev::WRITE"" etc." 4 |
1865 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
3286 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
1866 | .IX Item "ev::READ, ev::WRITE etc." |
3287 | .IX Item "ev::READ, ev::WRITE etc." |
1867 | These are just enum values with the same values as the \f(CW\*(C`EV_READ\*(C'\fR etc. |
3288 | These are just enum values with the same values as the \f(CW\*(C`EV_READ\*(C'\fR etc. |
1868 | macros from \fIev.h\fR. |
3289 | macros from \fIev.h\fR. |
1869 | .ie n .IP """ev::tstamp""\fR, \f(CW""ev::now""" 4 |
3290 | .ie n .IP """ev::tstamp"", ""ev::now""" 4 |
1870 | .el .IP "\f(CWev::tstamp\fR, \f(CWev::now\fR" 4 |
3291 | .el .IP "\f(CWev::tstamp\fR, \f(CWev::now\fR" 4 |
1871 | .IX Item "ev::tstamp, ev::now" |
3292 | .IX Item "ev::tstamp, ev::now" |
1872 | Aliases to the same types/functions as with the \f(CW\*(C`ev_\*(C'\fR prefix. |
3293 | Aliases to the same types/functions as with the \f(CW\*(C`ev_\*(C'\fR prefix. |
1873 | .ie n .IP """ev::io""\fR, \f(CW""ev::timer""\fR, \f(CW""ev::periodic""\fR, \f(CW""ev::idle""\fR, \f(CW""ev::sig"" etc." 4 |
3294 | .ie n .IP """ev::io"", ""ev::timer"", ""ev::periodic"", ""ev::idle"", ""ev::sig"" etc." 4 |
1874 | .el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4 |
3295 | .el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4 |
1875 | .IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc." |
3296 | .IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc." |
1876 | For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of |
3297 | For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of |
1877 | the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR |
3298 | the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR |
1878 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
3299 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
1879 | defines by many implementations. |
3300 | defines by many implementations. |
1880 | .Sp |
3301 | .Sp |
1881 | All of those classes have these methods: |
3302 | All of those classes have these methods: |
1882 | .RS 4 |
3303 | .RS 4 |
1883 | .IP "ev::TYPE::TYPE (object *, object::method *)" 4 |
3304 | .IP "ev::TYPE::TYPE ()" 4 |
1884 | .IX Item "ev::TYPE::TYPE (object *, object::method *)" |
3305 | .IX Item "ev::TYPE::TYPE ()" |
1885 | .PD 0 |
3306 | .PD 0 |
1886 | .IP "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" 4 |
3307 | .IP "ev::TYPE::TYPE (struct ev_loop *)" 4 |
1887 | .IX Item "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" |
3308 | .IX Item "ev::TYPE::TYPE (struct ev_loop *)" |
1888 | .IP "ev::TYPE::~TYPE" 4 |
3309 | .IP "ev::TYPE::~TYPE" 4 |
1889 | .IX Item "ev::TYPE::~TYPE" |
3310 | .IX Item "ev::TYPE::~TYPE" |
1890 | .PD |
3311 | .PD |
1891 | The constructor takes a pointer to an object and a method pointer to |
3312 | The constructor (optionally) takes an event loop to associate the watcher |
1892 | the event handler callback to call in this class. The constructor calls |
3313 | with. If it is omitted, it will use \f(CW\*(C`EV_DEFAULT\*(C'\fR. |
1893 | \&\f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the \f(CW\*(C`set\*(C'\fR method |
3314 | .Sp |
1894 | before starting it. If you do not specify a loop then the constructor |
3315 | The constructor calls \f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the |
1895 | automatically associates the default loop with this watcher. |
3316 | \&\f(CW\*(C`set\*(C'\fR method before starting it. |
|
|
3317 | .Sp |
|
|
3318 | It will not set a callback, however: You have to call the templated \f(CW\*(C`set\*(C'\fR |
|
|
3319 | method to set a callback before you can start the watcher. |
|
|
3320 | .Sp |
|
|
3321 | (The reason why you have to use a method is a limitation in \*(C+ which does |
|
|
3322 | not allow explicit template arguments for constructors). |
1896 | .Sp |
3323 | .Sp |
1897 | The destructor automatically stops the watcher if it is active. |
3324 | The destructor automatically stops the watcher if it is active. |
|
|
3325 | .IP "w\->set<class, &class::method> (object *)" 4 |
|
|
3326 | .IX Item "w->set<class, &class::method> (object *)" |
|
|
3327 | This method sets the callback method to call. The method has to have a |
|
|
3328 | signature of \f(CW\*(C`void (*)(ev_TYPE &, int)\*(C'\fR, it receives the watcher as |
|
|
3329 | first argument and the \f(CW\*(C`revents\*(C'\fR as second. The object must be given as |
|
|
3330 | parameter and is stored in the \f(CW\*(C`data\*(C'\fR member of the watcher. |
|
|
3331 | .Sp |
|
|
3332 | This method synthesizes efficient thunking code to call your method from |
|
|
3333 | the C callback that libev requires. If your compiler can inline your |
|
|
3334 | callback (i.e. it is visible to it at the place of the \f(CW\*(C`set\*(C'\fR call and |
|
|
3335 | your compiler is good :), then the method will be fully inlined into the |
|
|
3336 | thunking function, making it as fast as a direct C callback. |
|
|
3337 | .Sp |
|
|
3338 | Example: simple class declaration and watcher initialisation |
|
|
3339 | .Sp |
|
|
3340 | .Vb 4 |
|
|
3341 | \& struct myclass |
|
|
3342 | \& { |
|
|
3343 | \& void io_cb (ev::io &w, int revents) { } |
|
|
3344 | \& } |
|
|
3345 | \& |
|
|
3346 | \& myclass obj; |
|
|
3347 | \& ev::io iow; |
|
|
3348 | \& iow.set <myclass, &myclass::io_cb> (&obj); |
|
|
3349 | .Ve |
|
|
3350 | .IP "w\->set (object *)" 4 |
|
|
3351 | .IX Item "w->set (object *)" |
|
|
3352 | This is an \fBexperimental\fR feature that might go away in a future version. |
|
|
3353 | .Sp |
|
|
3354 | This is a variation of a method callback \- leaving out the method to call |
|
|
3355 | will default the method to \f(CW\*(C`operator ()\*(C'\fR, which makes it possible to use |
|
|
3356 | functor objects without having to manually specify the \f(CW\*(C`operator ()\*(C'\fR all |
|
|
3357 | the time. Incidentally, you can then also leave out the template argument |
|
|
3358 | list. |
|
|
3359 | .Sp |
|
|
3360 | The \f(CW\*(C`operator ()\*(C'\fR method prototype must be \f(CW\*(C`void operator ()(watcher &w, |
|
|
3361 | int revents)\*(C'\fR. |
|
|
3362 | .Sp |
|
|
3363 | See the method\-\f(CW\*(C`set\*(C'\fR above for more details. |
|
|
3364 | .Sp |
|
|
3365 | Example: use a functor object as callback. |
|
|
3366 | .Sp |
|
|
3367 | .Vb 7 |
|
|
3368 | \& struct myfunctor |
|
|
3369 | \& { |
|
|
3370 | \& void operator() (ev::io &w, int revents) |
|
|
3371 | \& { |
|
|
3372 | \& ... |
|
|
3373 | \& } |
|
|
3374 | \& } |
|
|
3375 | \& |
|
|
3376 | \& myfunctor f; |
|
|
3377 | \& |
|
|
3378 | \& ev::io w; |
|
|
3379 | \& w.set (&f); |
|
|
3380 | .Ve |
|
|
3381 | .IP "w\->set<function> (void *data = 0)" 4 |
|
|
3382 | .IX Item "w->set<function> (void *data = 0)" |
|
|
3383 | Also sets a callback, but uses a static method or plain function as |
|
|
3384 | callback. The optional \f(CW\*(C`data\*(C'\fR argument will be stored in the watcher's |
|
|
3385 | \&\f(CW\*(C`data\*(C'\fR member and is free for you to use. |
|
|
3386 | .Sp |
|
|
3387 | The prototype of the \f(CW\*(C`function\*(C'\fR must be \f(CW\*(C`void (*)(ev::TYPE &w, int)\*(C'\fR. |
|
|
3388 | .Sp |
|
|
3389 | See the method\-\f(CW\*(C`set\*(C'\fR above for more details. |
|
|
3390 | .Sp |
|
|
3391 | Example: Use a plain function as callback. |
|
|
3392 | .Sp |
|
|
3393 | .Vb 2 |
|
|
3394 | \& static void io_cb (ev::io &w, int revents) { } |
|
|
3395 | \& iow.set <io_cb> (); |
|
|
3396 | .Ve |
1898 | .IP "w\->set (struct ev_loop *)" 4 |
3397 | .IP "w\->set (struct ev_loop *)" 4 |
1899 | .IX Item "w->set (struct ev_loop *)" |
3398 | .IX Item "w->set (struct ev_loop *)" |
1900 | Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only |
3399 | Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only |
1901 | do this when the watcher is inactive (and not pending either). |
3400 | do this when the watcher is inactive (and not pending either). |
1902 | .IP "w\->set ([args])" 4 |
3401 | .IP "w\->set ([arguments])" 4 |
1903 | .IX Item "w->set ([args])" |
3402 | .IX Item "w->set ([arguments])" |
1904 | Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be |
3403 | Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same arguments. Must be |
1905 | called at least once. Unlike the C counterpart, an active watcher gets |
3404 | called at least once. Unlike the C counterpart, an active watcher gets |
1906 | automatically stopped and restarted. |
3405 | automatically stopped and restarted when reconfiguring it with this |
|
|
3406 | method. |
1907 | .IP "w\->start ()" 4 |
3407 | .IP "w\->start ()" 4 |
1908 | .IX Item "w->start ()" |
3408 | .IX Item "w->start ()" |
1909 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument as the |
3409 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the |
1910 | constructor already takes the loop. |
3410 | constructor already stores the event loop. |
1911 | .IP "w\->stop ()" 4 |
3411 | .IP "w\->stop ()" 4 |
1912 | .IX Item "w->stop ()" |
3412 | .IX Item "w->stop ()" |
1913 | Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. |
3413 | Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. |
1914 | .ie n .IP "w\->again () ""ev::timer""\fR, \f(CW""ev::periodic"" only" 4 |
3414 | .ie n .IP "w\->again () (""ev::timer"", ""ev::periodic"" only)" 4 |
1915 | .el .IP "w\->again () \f(CWev::timer\fR, \f(CWev::periodic\fR only" 4 |
3415 | .el .IP "w\->again () (\f(CWev::timer\fR, \f(CWev::periodic\fR only)" 4 |
1916 | .IX Item "w->again () ev::timer, ev::periodic only" |
3416 | .IX Item "w->again () (ev::timer, ev::periodic only)" |
1917 | For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding |
3417 | For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding |
1918 | \&\f(CW\*(C`ev_TYPE_again\*(C'\fR function. |
3418 | \&\f(CW\*(C`ev_TYPE_again\*(C'\fR function. |
1919 | .ie n .IP "w\->sweep () ""ev::embed"" only" 4 |
3419 | .ie n .IP "w\->sweep () (""ev::embed"" only)" 4 |
1920 | .el .IP "w\->sweep () \f(CWev::embed\fR only" 4 |
3420 | .el .IP "w\->sweep () (\f(CWev::embed\fR only)" 4 |
1921 | .IX Item "w->sweep () ev::embed only" |
3421 | .IX Item "w->sweep () (ev::embed only)" |
1922 | Invokes \f(CW\*(C`ev_embed_sweep\*(C'\fR. |
3422 | Invokes \f(CW\*(C`ev_embed_sweep\*(C'\fR. |
1923 | .ie n .IP "w\->update () ""ev::stat"" only" 4 |
3423 | .ie n .IP "w\->update () (""ev::stat"" only)" 4 |
1924 | .el .IP "w\->update () \f(CWev::stat\fR only" 4 |
3424 | .el .IP "w\->update () (\f(CWev::stat\fR only)" 4 |
1925 | .IX Item "w->update () ev::stat only" |
3425 | .IX Item "w->update () (ev::stat only)" |
1926 | Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR. |
3426 | Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR. |
1927 | .RE |
3427 | .RE |
1928 | .RS 4 |
3428 | .RS 4 |
1929 | .RE |
3429 | .RE |
1930 | .PP |
3430 | .PP |
1931 | Example: Define a class with an \s-1IO\s0 and idle watcher, start one of them in |
3431 | Example: Define a class with an \s-1IO\s0 and idle watcher, start one of them in |
1932 | the constructor. |
3432 | the constructor. |
1933 | .PP |
3433 | .PP |
1934 | .Vb 4 |
3434 | .Vb 4 |
1935 | \& class myclass |
3435 | \& class myclass |
1936 | \& { |
3436 | \& { |
1937 | \& ev_io io; void io_cb (ev::io &w, int revents); |
3437 | \& ev::io io ; void io_cb (ev::io &w, int revents); |
1938 | \& ev_idle idle void idle_cb (ev::idle &w, int revents); |
3438 | \& ev::idle idle; void idle_cb (ev::idle &w, int revents); |
1939 | .Ve |
3439 | \& |
1940 | .PP |
|
|
1941 | .Vb 2 |
|
|
1942 | \& myclass (); |
3440 | \& myclass (int fd) |
1943 | \& } |
|
|
1944 | .Ve |
|
|
1945 | .PP |
|
|
1946 | .Vb 6 |
|
|
1947 | \& myclass::myclass (int fd) |
|
|
1948 | \& : io (this, &myclass::io_cb), |
|
|
1949 | \& idle (this, &myclass::idle_cb) |
|
|
1950 | \& { |
3441 | \& { |
|
|
3442 | \& io .set <myclass, &myclass::io_cb > (this); |
|
|
3443 | \& idle.set <myclass, &myclass::idle_cb> (this); |
|
|
3444 | \& |
1951 | \& io.start (fd, ev::READ); |
3445 | \& io.start (fd, ev::READ); |
|
|
3446 | \& } |
1952 | \& } |
3447 | \& }; |
1953 | .Ve |
3448 | .Ve |
|
|
3449 | .SH "OTHER LANGUAGE BINDINGS" |
|
|
3450 | .IX Header "OTHER LANGUAGE BINDINGS" |
|
|
3451 | Libev does not offer other language bindings itself, but bindings for a |
|
|
3452 | number of languages exist in the form of third-party packages. If you know |
|
|
3453 | any interesting language binding in addition to the ones listed here, drop |
|
|
3454 | me a note. |
|
|
3455 | .IP "Perl" 4 |
|
|
3456 | .IX Item "Perl" |
|
|
3457 | The \s-1EV\s0 module implements the full libev \s-1API\s0 and is actually used to test |
|
|
3458 | libev. \s-1EV\s0 is developed together with libev. Apart from the \s-1EV\s0 core module, |
|
|
3459 | there are additional modules that implement libev-compatible interfaces |
|
|
3460 | to \f(CW\*(C`libadns\*(C'\fR (\f(CW\*(C`EV::ADNS\*(C'\fR, but \f(CW\*(C`AnyEvent::DNS\*(C'\fR is preferred nowadays), |
|
|
3461 | \&\f(CW\*(C`Net::SNMP\*(C'\fR (\f(CW\*(C`Net::SNMP::EV\*(C'\fR) and the \f(CW\*(C`libglib\*(C'\fR event core (\f(CW\*(C`Glib::EV\*(C'\fR |
|
|
3462 | and \f(CW\*(C`EV::Glib\*(C'\fR). |
|
|
3463 | .Sp |
|
|
3464 | It can be found and installed via \s-1CPAN\s0, its homepage is at |
|
|
3465 | <http://software.schmorp.de/pkg/EV>. |
|
|
3466 | .IP "Python" 4 |
|
|
3467 | .IX Item "Python" |
|
|
3468 | Python bindings can be found at <http://code.google.com/p/pyev/>. It |
|
|
3469 | seems to be quite complete and well-documented. |
|
|
3470 | .IP "Ruby" 4 |
|
|
3471 | .IX Item "Ruby" |
|
|
3472 | Tony Arcieri has written a ruby extension that offers access to a subset |
|
|
3473 | of the libev \s-1API\s0 and adds file handle abstractions, asynchronous \s-1DNS\s0 and |
|
|
3474 | more on top of it. It can be found via gem servers. Its homepage is at |
|
|
3475 | <http://rev.rubyforge.org/>. |
|
|
3476 | .Sp |
|
|
3477 | Roger Pack reports that using the link order \f(CW\*(C`\-lws2_32 \-lmsvcrt\-ruby\-190\*(C'\fR |
|
|
3478 | makes rev work even on mingw. |
|
|
3479 | .IP "Haskell" 4 |
|
|
3480 | .IX Item "Haskell" |
|
|
3481 | A haskell binding to libev is available at |
|
|
3482 | <http://hackage.haskell.org/cgi\-bin/hackage\-scripts/package/hlibev>. |
|
|
3483 | .IP "D" 4 |
|
|
3484 | .IX Item "D" |
|
|
3485 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
|
|
3486 | be found at <http://proj.llucax.com.ar/wiki/evd>. |
|
|
3487 | .IP "Ocaml" 4 |
|
|
3488 | .IX Item "Ocaml" |
|
|
3489 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
|
|
3490 | <http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/>. |
1954 | .SH "MACRO MAGIC" |
3491 | .SH "MACRO MAGIC" |
1955 | .IX Header "MACRO MAGIC" |
3492 | .IX Header "MACRO MAGIC" |
1956 | Libev can be compiled with a variety of options, the most fundemantal is |
3493 | Libev can be compiled with a variety of options, the most fundamental |
1957 | \&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines wether (most) functions and |
3494 | of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) |
1958 | callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
3495 | functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
1959 | .PP |
3496 | .PP |
1960 | To make it easier to write programs that cope with either variant, the |
3497 | To make it easier to write programs that cope with either variant, the |
1961 | following macros are defined: |
3498 | following macros are defined: |
1962 | .ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4 |
3499 | .ie n .IP """EV_A"", ""EV_A_""" 4 |
1963 | .el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4 |
3500 | .el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4 |
1964 | .IX Item "EV_A, EV_A_" |
3501 | .IX Item "EV_A, EV_A_" |
1965 | This provides the loop \fIargument\fR for functions, if one is required (\*(L"ev |
3502 | This provides the loop \fIargument\fR for functions, if one is required (\*(L"ev |
1966 | loop argument\*(R"). The \f(CW\*(C`EV_A\*(C'\fR form is used when this is the sole argument, |
3503 | loop argument\*(R"). The \f(CW\*(C`EV_A\*(C'\fR form is used when this is the sole argument, |
1967 | \&\f(CW\*(C`EV_A_\*(C'\fR is used when other arguments are following. Example: |
3504 | \&\f(CW\*(C`EV_A_\*(C'\fR is used when other arguments are following. Example: |
1968 | .Sp |
3505 | .Sp |
1969 | .Vb 3 |
3506 | .Vb 3 |
1970 | \& ev_unref (EV_A); |
3507 | \& ev_unref (EV_A); |
1971 | \& ev_timer_add (EV_A_ watcher); |
3508 | \& ev_timer_add (EV_A_ watcher); |
1972 | \& ev_loop (EV_A_ 0); |
3509 | \& ev_loop (EV_A_ 0); |
1973 | .Ve |
3510 | .Ve |
1974 | .Sp |
3511 | .Sp |
1975 | It assumes the variable \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR is in scope, |
3512 | It assumes the variable \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR is in scope, |
1976 | which is often provided by the following macro. |
3513 | which is often provided by the following macro. |
1977 | .ie n .IP """EV_P""\fR, \f(CW""EV_P_""" 4 |
3514 | .ie n .IP """EV_P"", ""EV_P_""" 4 |
1978 | .el .IP "\f(CWEV_P\fR, \f(CWEV_P_\fR" 4 |
3515 | .el .IP "\f(CWEV_P\fR, \f(CWEV_P_\fR" 4 |
1979 | .IX Item "EV_P, EV_P_" |
3516 | .IX Item "EV_P, EV_P_" |
1980 | This provides the loop \fIparameter\fR for functions, if one is required (\*(L"ev |
3517 | This provides the loop \fIparameter\fR for functions, if one is required (\*(L"ev |
1981 | loop parameter\*(R"). The \f(CW\*(C`EV_P\*(C'\fR form is used when this is the sole parameter, |
3518 | loop parameter\*(R"). The \f(CW\*(C`EV_P\*(C'\fR form is used when this is the sole parameter, |
1982 | \&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example: |
3519 | \&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example: |
1983 | .Sp |
3520 | .Sp |
1984 | .Vb 2 |
3521 | .Vb 2 |
1985 | \& // this is how ev_unref is being declared |
3522 | \& // this is how ev_unref is being declared |
1986 | \& static void ev_unref (EV_P); |
3523 | \& static void ev_unref (EV_P); |
1987 | .Ve |
3524 | \& |
1988 | .Sp |
|
|
1989 | .Vb 2 |
|
|
1990 | \& // this is how you can declare your typical callback |
3525 | \& // this is how you can declare your typical callback |
1991 | \& static void cb (EV_P_ ev_timer *w, int revents) |
3526 | \& static void cb (EV_P_ ev_timer *w, int revents) |
1992 | .Ve |
3527 | .Ve |
1993 | .Sp |
3528 | .Sp |
1994 | It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite |
3529 | It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite |
1995 | suitable for use with \f(CW\*(C`EV_A\*(C'\fR. |
3530 | suitable for use with \f(CW\*(C`EV_A\*(C'\fR. |
1996 | .ie n .IP """EV_DEFAULT""\fR, \f(CW""EV_DEFAULT_""" 4 |
3531 | .ie n .IP """EV_DEFAULT"", ""EV_DEFAULT_""" 4 |
1997 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
3532 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
1998 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
3533 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
1999 | Similar to the other two macros, this gives you the value of the default |
3534 | Similar to the other two macros, this gives you the value of the default |
2000 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). |
3535 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). |
|
|
3536 | .ie n .IP """EV_DEFAULT_UC"", ""EV_DEFAULT_UC_""" 4 |
|
|
3537 | .el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4 |
|
|
3538 | .IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_" |
|
|
3539 | Usage identical to \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR, but requires that the |
|
|
3540 | default loop has been initialised (\f(CW\*(C`UC\*(C'\fR == unchecked). Their behaviour |
|
|
3541 | is undefined when the default loop has not been initialised by a previous |
|
|
3542 | execution of \f(CW\*(C`EV_DEFAULT\*(C'\fR, \f(CW\*(C`EV_DEFAULT_\*(C'\fR or \f(CW\*(C`ev_default_init (...)\*(C'\fR. |
|
|
3543 | .Sp |
|
|
3544 | It is often prudent to use \f(CW\*(C`EV_DEFAULT\*(C'\fR when initialising the first |
|
|
3545 | watcher in a function but use \f(CW\*(C`EV_DEFAULT_UC\*(C'\fR afterwards. |
2001 | .PP |
3546 | .PP |
2002 | Example: Declare and initialise a check watcher, utilising the above |
3547 | Example: Declare and initialise a check watcher, utilising the above |
2003 | macros so it will work regardless of wether multiple loops are supported |
3548 | macros so it will work regardless of whether multiple loops are supported |
2004 | or not. |
3549 | or not. |
2005 | .PP |
3550 | .PP |
2006 | .Vb 5 |
3551 | .Vb 5 |
2007 | \& static void |
3552 | \& static void |
2008 | \& check_cb (EV_P_ ev_timer *w, int revents) |
3553 | \& check_cb (EV_P_ ev_timer *w, int revents) |
2009 | \& { |
3554 | \& { |
2010 | \& ev_check_stop (EV_A_ w); |
3555 | \& ev_check_stop (EV_A_ w); |
2011 | \& } |
3556 | \& } |
2012 | .Ve |
3557 | \& |
2013 | .PP |
|
|
2014 | .Vb 4 |
|
|
2015 | \& ev_check check; |
3558 | \& ev_check check; |
2016 | \& ev_check_init (&check, check_cb); |
3559 | \& ev_check_init (&check, check_cb); |
2017 | \& ev_check_start (EV_DEFAULT_ &check); |
3560 | \& ev_check_start (EV_DEFAULT_ &check); |
2018 | \& ev_loop (EV_DEFAULT_ 0); |
3561 | \& ev_loop (EV_DEFAULT_ 0); |
2019 | .Ve |
3562 | .Ve |
2020 | .SH "EMBEDDING" |
3563 | .SH "EMBEDDING" |
2021 | .IX Header "EMBEDDING" |
3564 | .IX Header "EMBEDDING" |
2022 | Libev can (and often is) directly embedded into host |
3565 | Libev can (and often is) directly embedded into host |
2023 | applications. Examples of applications that embed it include the Deliantra |
3566 | applications. Examples of applications that embed it include the Deliantra |
2024 | Game Server, the \s-1EV\s0 perl module, the \s-1GNU\s0 Virtual Private Ethernet (gvpe) |
3567 | Game Server, the \s-1EV\s0 perl module, the \s-1GNU\s0 Virtual Private Ethernet (gvpe) |
2025 | and rxvt\-unicode. |
3568 | and rxvt-unicode. |
2026 | .PP |
3569 | .PP |
2027 | The goal is to enable you to just copy the neecssary files into your |
3570 | The goal is to enable you to just copy the necessary files into your |
2028 | source directory without having to change even a single line in them, so |
3571 | source directory without having to change even a single line in them, so |
2029 | you can easily upgrade by simply copying (or having a checked-out copy of |
3572 | you can easily upgrade by simply copying (or having a checked-out copy of |
2030 | libev somewhere in your source tree). |
3573 | libev somewhere in your source tree). |
2031 | .Sh "\s-1FILESETS\s0" |
3574 | .SS "\s-1FILESETS\s0" |
2032 | .IX Subsection "FILESETS" |
3575 | .IX Subsection "FILESETS" |
2033 | Depending on what features you need you need to include one or more sets of files |
3576 | Depending on what features you need you need to include one or more sets of files |
2034 | in your app. |
3577 | in your application. |
2035 | .PP |
3578 | .PP |
2036 | \fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR |
3579 | \fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR |
2037 | .IX Subsection "CORE EVENT LOOP" |
3580 | .IX Subsection "CORE EVENT LOOP" |
2038 | .PP |
3581 | .PP |
2039 | To include only the libev core (all the \f(CW\*(C`ev_*\*(C'\fR functions), with manual |
3582 | To include only the libev core (all the \f(CW\*(C`ev_*\*(C'\fR functions), with manual |
2040 | configuration (no autoconf): |
3583 | configuration (no autoconf): |
2041 | .PP |
3584 | .PP |
2042 | .Vb 2 |
3585 | .Vb 2 |
2043 | \& #define EV_STANDALONE 1 |
3586 | \& #define EV_STANDALONE 1 |
2044 | \& #include "ev.c" |
3587 | \& #include "ev.c" |
2045 | .Ve |
3588 | .Ve |
2046 | .PP |
3589 | .PP |
2047 | This will automatically include \fIev.h\fR, too, and should be done in a |
3590 | This will automatically include \fIev.h\fR, too, and should be done in a |
2048 | single C source file only to provide the function implementations. To use |
3591 | single C source file only to provide the function implementations. To use |
2049 | it, do the same for \fIev.h\fR in all files wishing to use this \s-1API\s0 (best |
3592 | it, do the same for \fIev.h\fR in all files wishing to use this \s-1API\s0 (best |
2050 | done by writing a wrapper around \fIev.h\fR that you can include instead and |
3593 | done by writing a wrapper around \fIev.h\fR that you can include instead and |
2051 | where you can put other configuration options): |
3594 | where you can put other configuration options): |
2052 | .PP |
3595 | .PP |
2053 | .Vb 2 |
3596 | .Vb 2 |
2054 | \& #define EV_STANDALONE 1 |
3597 | \& #define EV_STANDALONE 1 |
2055 | \& #include "ev.h" |
3598 | \& #include "ev.h" |
2056 | .Ve |
3599 | .Ve |
2057 | .PP |
3600 | .PP |
2058 | Both header files and implementation files can be compiled with a \*(C+ |
3601 | Both header files and implementation files can be compiled with a \*(C+ |
2059 | compiler (at least, thats a stated goal, and breakage will be treated |
3602 | compiler (at least, that's a stated goal, and breakage will be treated |
2060 | as a bug). |
3603 | as a bug). |
2061 | .PP |
3604 | .PP |
2062 | You need the following files in your source tree, or in a directory |
3605 | You need the following files in your source tree, or in a directory |
2063 | in your include path (e.g. in libev/ when using \-Ilibev): |
3606 | in your include path (e.g. in libev/ when using \-Ilibev): |
2064 | .PP |
3607 | .PP |
2065 | .Vb 4 |
3608 | .Vb 4 |
2066 | \& ev.h |
3609 | \& ev.h |
2067 | \& ev.c |
3610 | \& ev.c |
2068 | \& ev_vars.h |
3611 | \& ev_vars.h |
2069 | \& ev_wrap.h |
3612 | \& ev_wrap.h |
2070 | .Ve |
3613 | \& |
2071 | .PP |
|
|
2072 | .Vb 1 |
|
|
2073 | \& ev_win32.c required on win32 platforms only |
3614 | \& ev_win32.c required on win32 platforms only |
2074 | .Ve |
3615 | \& |
2075 | .PP |
|
|
2076 | .Vb 5 |
|
|
2077 | \& ev_select.c only when select backend is enabled (which is enabled by default) |
3616 | \& ev_select.c only when select backend is enabled (which is enabled by default) |
2078 | \& ev_poll.c only when poll backend is enabled (disabled by default) |
3617 | \& ev_poll.c only when poll backend is enabled (disabled by default) |
2079 | \& ev_epoll.c only when the epoll backend is enabled (disabled by default) |
3618 | \& ev_epoll.c only when the epoll backend is enabled (disabled by default) |
2080 | \& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
3619 | \& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
2081 | \& ev_port.c only when the solaris port backend is enabled (disabled by default) |
3620 | \& ev_port.c only when the solaris port backend is enabled (disabled by default) |
2082 | .Ve |
3621 | .Ve |
2083 | .PP |
3622 | .PP |
2084 | \&\fIev.c\fR includes the backend files directly when enabled, so you only need |
3623 | \&\fIev.c\fR includes the backend files directly when enabled, so you only need |
2085 | to compile this single file. |
3624 | to compile this single file. |
2086 | .PP |
3625 | .PP |
… | |
… | |
2088 | .IX Subsection "LIBEVENT COMPATIBILITY API" |
3627 | .IX Subsection "LIBEVENT COMPATIBILITY API" |
2089 | .PP |
3628 | .PP |
2090 | To include the libevent compatibility \s-1API\s0, also include: |
3629 | To include the libevent compatibility \s-1API\s0, also include: |
2091 | .PP |
3630 | .PP |
2092 | .Vb 1 |
3631 | .Vb 1 |
2093 | \& #include "event.c" |
3632 | \& #include "event.c" |
2094 | .Ve |
3633 | .Ve |
2095 | .PP |
3634 | .PP |
2096 | in the file including \fIev.c\fR, and: |
3635 | in the file including \fIev.c\fR, and: |
2097 | .PP |
3636 | .PP |
2098 | .Vb 1 |
3637 | .Vb 1 |
2099 | \& #include "event.h" |
3638 | \& #include "event.h" |
2100 | .Ve |
3639 | .Ve |
2101 | .PP |
3640 | .PP |
2102 | in the files that want to use the libevent \s-1API\s0. This also includes \fIev.h\fR. |
3641 | in the files that want to use the libevent \s-1API\s0. This also includes \fIev.h\fR. |
2103 | .PP |
3642 | .PP |
2104 | You need the following additional files for this: |
3643 | You need the following additional files for this: |
2105 | .PP |
3644 | .PP |
2106 | .Vb 2 |
3645 | .Vb 2 |
2107 | \& event.h |
3646 | \& event.h |
2108 | \& event.c |
3647 | \& event.c |
2109 | .Ve |
3648 | .Ve |
2110 | .PP |
3649 | .PP |
2111 | \fI\s-1AUTOCONF\s0 \s-1SUPPORT\s0\fR |
3650 | \fI\s-1AUTOCONF\s0 \s-1SUPPORT\s0\fR |
2112 | .IX Subsection "AUTOCONF SUPPORT" |
3651 | .IX Subsection "AUTOCONF SUPPORT" |
2113 | .PP |
3652 | .PP |
2114 | Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your config in |
3653 | Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your configuration in |
2115 | whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your |
3654 | whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your |
2116 | \&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then |
3655 | \&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then |
2117 | include \fIconfig.h\fR and configure itself accordingly. |
3656 | include \fIconfig.h\fR and configure itself accordingly. |
2118 | .PP |
3657 | .PP |
2119 | For this of course you need the m4 file: |
3658 | For this of course you need the m4 file: |
2120 | .PP |
3659 | .PP |
2121 | .Vb 1 |
3660 | .Vb 1 |
2122 | \& libev.m4 |
3661 | \& libev.m4 |
2123 | .Ve |
3662 | .Ve |
2124 | .Sh "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" |
3663 | .SS "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" |
2125 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
3664 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
2126 | Libev can be configured via a variety of preprocessor symbols you have to define |
3665 | Libev can be configured via a variety of preprocessor symbols you have to |
2127 | before including any of its files. The default is not to build for multiplicity |
3666 | define before including any of its files. The default in the absence of |
2128 | and only include the select backend. |
3667 | autoconf is documented for every option. |
2129 | .IP "\s-1EV_STANDALONE\s0" 4 |
3668 | .IP "\s-1EV_STANDALONE\s0" 4 |
2130 | .IX Item "EV_STANDALONE" |
3669 | .IX Item "EV_STANDALONE" |
2131 | Must always be \f(CW1\fR if you do not use autoconf configuration, which |
3670 | Must always be \f(CW1\fR if you do not use autoconf configuration, which |
2132 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
3671 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
2133 | implementations for some libevent functions (such as logging, which is not |
3672 | implementations for some libevent functions (such as logging, which is not |
2134 | supported). It will also not define any of the structs usually found in |
3673 | supported). It will also not define any of the structs usually found in |
2135 | \&\fIevent.h\fR that are not directly supported by the libev core alone. |
3674 | \&\fIevent.h\fR that are not directly supported by the libev core alone. |
|
|
3675 | .Sp |
|
|
3676 | In stanbdalone mode, libev will still try to automatically deduce the |
|
|
3677 | configuration, but has to be more conservative. |
2136 | .IP "\s-1EV_USE_MONOTONIC\s0" 4 |
3678 | .IP "\s-1EV_USE_MONOTONIC\s0" 4 |
2137 | .IX Item "EV_USE_MONOTONIC" |
3679 | .IX Item "EV_USE_MONOTONIC" |
2138 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
3680 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
2139 | monotonic clock option at both compiletime and runtime. Otherwise no use |
3681 | monotonic clock option at both compile time and runtime. Otherwise no |
2140 | of the monotonic clock option will be attempted. If you enable this, you |
3682 | use of the monotonic clock option will be attempted. If you enable this, |
2141 | usually have to link against librt or something similar. Enabling it when |
3683 | you usually have to link against librt or something similar. Enabling it |
2142 | the functionality isn't available is safe, though, althoguh you have |
3684 | when the functionality isn't available is safe, though, although you have |
2143 | to make sure you link against any libraries where the \f(CW\*(C`clock_gettime\*(C'\fR |
3685 | to make sure you link against any libraries where the \f(CW\*(C`clock_gettime\*(C'\fR |
2144 | function is hiding in (often \fI\-lrt\fR). |
3686 | function is hiding in (often \fI\-lrt\fR). See also \f(CW\*(C`EV_USE_CLOCK_SYSCALL\*(C'\fR. |
2145 | .IP "\s-1EV_USE_REALTIME\s0" 4 |
3687 | .IP "\s-1EV_USE_REALTIME\s0" 4 |
2146 | .IX Item "EV_USE_REALTIME" |
3688 | .IX Item "EV_USE_REALTIME" |
2147 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
3689 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
2148 | realtime clock option at compiletime (and assume its availability at |
3690 | real-time clock option at compile time (and assume its availability |
2149 | runtime if successful). Otherwise no use of the realtime clock option will |
3691 | at runtime if successful). Otherwise no use of the real-time clock |
2150 | be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR by \f(CW\*(C`clock_get |
3692 | option will be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR |
2151 | (CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect correctness. See tzhe note about libraries |
3693 | by \f(CW\*(C`clock_get (CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect |
2152 | in the description of \f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though. |
3694 | correctness. See the note about libraries in the description of |
|
|
3695 | \&\f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though. Defaults to the opposite value of |
|
|
3696 | \&\f(CW\*(C`EV_USE_CLOCK_SYSCALL\*(C'\fR. |
|
|
3697 | .IP "\s-1EV_USE_CLOCK_SYSCALL\s0" 4 |
|
|
3698 | .IX Item "EV_USE_CLOCK_SYSCALL" |
|
|
3699 | If defined to be \f(CW1\fR, libev will try to use a direct syscall instead |
|
|
3700 | of calling the system-provided \f(CW\*(C`clock_gettime\*(C'\fR function. This option |
|
|
3701 | exists because on GNU/Linux, \f(CW\*(C`clock_gettime\*(C'\fR is in \f(CW\*(C`librt\*(C'\fR, but \f(CW\*(C`librt\*(C'\fR |
|
|
3702 | unconditionally pulls in \f(CW\*(C`libpthread\*(C'\fR, slowing down single-threaded |
|
|
3703 | programs needlessly. Using a direct syscall is slightly slower (in |
|
|
3704 | theory), because no optimised vdso implementation can be used, but avoids |
|
|
3705 | the pthread dependency. Defaults to \f(CW1\fR on GNU/Linux with glibc 2.x or |
|
|
3706 | higher, as it simplifies linking (no need for \f(CW\*(C`\-lrt\*(C'\fR). |
|
|
3707 | .IP "\s-1EV_USE_NANOSLEEP\s0" 4 |
|
|
3708 | .IX Item "EV_USE_NANOSLEEP" |
|
|
3709 | If defined to be \f(CW1\fR, libev will assume that \f(CW\*(C`nanosleep ()\*(C'\fR is available |
|
|
3710 | and will use it for delays. Otherwise it will use \f(CW\*(C`select ()\*(C'\fR. |
|
|
3711 | .IP "\s-1EV_USE_EVENTFD\s0" 4 |
|
|
3712 | .IX Item "EV_USE_EVENTFD" |
|
|
3713 | If defined to be \f(CW1\fR, then libev will assume that \f(CW\*(C`eventfd ()\*(C'\fR is |
|
|
3714 | available and will probe for kernel support at runtime. This will improve |
|
|
3715 | \&\f(CW\*(C`ev_signal\*(C'\fR and \f(CW\*(C`ev_async\*(C'\fR performance and reduce resource consumption. |
|
|
3716 | If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc |
|
|
3717 | 2.7 or newer, otherwise disabled. |
2153 | .IP "\s-1EV_USE_SELECT\s0" 4 |
3718 | .IP "\s-1EV_USE_SELECT\s0" 4 |
2154 | .IX Item "EV_USE_SELECT" |
3719 | .IX Item "EV_USE_SELECT" |
2155 | If undefined or defined to be \f(CW1\fR, libev will compile in support for the |
3720 | If undefined or defined to be \f(CW1\fR, libev will compile in support for the |
2156 | \&\f(CW\*(C`select\*(C'\fR(2) backend. No attempt at autodetection will be done: if no |
3721 | \&\f(CW\*(C`select\*(C'\fR(2) backend. No attempt at auto-detection will be done: if no |
2157 | other method takes over, select will be it. Otherwise the select backend |
3722 | other method takes over, select will be it. Otherwise the select backend |
2158 | will not be compiled in. |
3723 | will not be compiled in. |
2159 | .IP "\s-1EV_SELECT_USE_FD_SET\s0" 4 |
3724 | .IP "\s-1EV_SELECT_USE_FD_SET\s0" 4 |
2160 | .IX Item "EV_SELECT_USE_FD_SET" |
3725 | .IX Item "EV_SELECT_USE_FD_SET" |
2161 | If defined to \f(CW1\fR, then the select backend will use the system \f(CW\*(C`fd_set\*(C'\fR |
3726 | If defined to \f(CW1\fR, then the select backend will use the system \f(CW\*(C`fd_set\*(C'\fR |
2162 | structure. This is useful if libev doesn't compile due to a missing |
3727 | structure. This is useful if libev doesn't compile due to a missing |
2163 | \&\f(CW\*(C`NFDBITS\*(C'\fR or \f(CW\*(C`fd_mask\*(C'\fR definition or it misguesses the bitset layout on |
3728 | \&\f(CW\*(C`NFDBITS\*(C'\fR or \f(CW\*(C`fd_mask\*(C'\fR definition or it mis-guesses the bitset layout |
2164 | exotic systems. This usually limits the range of file descriptors to some |
3729 | on exotic systems. This usually limits the range of file descriptors to |
2165 | low limit such as 1024 or might have other limitations (winsocket only |
3730 | some low limit such as 1024 or might have other limitations (winsocket |
2166 | allows 64 sockets). The \f(CW\*(C`FD_SETSIZE\*(C'\fR macro, set before compilation, might |
3731 | only allows 64 sockets). The \f(CW\*(C`FD_SETSIZE\*(C'\fR macro, set before compilation, |
2167 | influence the size of the \f(CW\*(C`fd_set\*(C'\fR used. |
3732 | configures the maximum size of the \f(CW\*(C`fd_set\*(C'\fR. |
2168 | .IP "\s-1EV_SELECT_IS_WINSOCKET\s0" 4 |
3733 | .IP "\s-1EV_SELECT_IS_WINSOCKET\s0" 4 |
2169 | .IX Item "EV_SELECT_IS_WINSOCKET" |
3734 | .IX Item "EV_SELECT_IS_WINSOCKET" |
2170 | When defined to \f(CW1\fR, the select backend will assume that |
3735 | When defined to \f(CW1\fR, the select backend will assume that |
2171 | select/socket/connect etc. don't understand file descriptors but |
3736 | select/socket/connect etc. don't understand file descriptors but |
2172 | wants osf handles on win32 (this is the case when the select to |
3737 | wants osf handles on win32 (this is the case when the select to |
2173 | be used is the winsock select). This means that it will call |
3738 | be used is the winsock select). This means that it will call |
2174 | \&\f(CW\*(C`_get_osfhandle\*(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise, |
3739 | \&\f(CW\*(C`_get_osfhandle\*(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise, |
2175 | it is assumed that all these functions actually work on fds, even |
3740 | it is assumed that all these functions actually work on fds, even |
2176 | on win32. Should not be defined on non\-win32 platforms. |
3741 | on win32. Should not be defined on non\-win32 platforms. |
|
|
3742 | .IP "\s-1EV_FD_TO_WIN32_HANDLE\s0" 4 |
|
|
3743 | .IX Item "EV_FD_TO_WIN32_HANDLE" |
|
|
3744 | If \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR is enabled, then libev needs a way to map |
|
|
3745 | file descriptors to socket handles. When not defining this symbol (the |
|
|
3746 | default), then libev will call \f(CW\*(C`_get_osfhandle\*(C'\fR, which is usually |
|
|
3747 | correct. In some cases, programs use their own file descriptor management, |
|
|
3748 | in which case they can provide this function to map fds to socket handles. |
2177 | .IP "\s-1EV_USE_POLL\s0" 4 |
3749 | .IP "\s-1EV_USE_POLL\s0" 4 |
2178 | .IX Item "EV_USE_POLL" |
3750 | .IX Item "EV_USE_POLL" |
2179 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
3751 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
2180 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
3752 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
2181 | takes precedence over select. |
3753 | takes precedence over select. |
2182 | .IP "\s-1EV_USE_EPOLL\s0" 4 |
3754 | .IP "\s-1EV_USE_EPOLL\s0" 4 |
2183 | .IX Item "EV_USE_EPOLL" |
3755 | .IX Item "EV_USE_EPOLL" |
2184 | If defined to be \f(CW1\fR, libev will compile in support for the Linux |
3756 | If defined to be \f(CW1\fR, libev will compile in support for the Linux |
2185 | \&\f(CW\*(C`epoll\*(C'\fR(7) backend. Its availability will be detected at runtime, |
3757 | \&\f(CW\*(C`epoll\*(C'\fR(7) backend. Its availability will be detected at runtime, |
2186 | otherwise another method will be used as fallback. This is the |
3758 | otherwise another method will be used as fallback. This is the preferred |
2187 | preferred backend for GNU/Linux systems. |
3759 | backend for GNU/Linux systems. If undefined, it will be enabled if the |
|
|
3760 | headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
2188 | .IP "\s-1EV_USE_KQUEUE\s0" 4 |
3761 | .IP "\s-1EV_USE_KQUEUE\s0" 4 |
2189 | .IX Item "EV_USE_KQUEUE" |
3762 | .IX Item "EV_USE_KQUEUE" |
2190 | If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style |
3763 | If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style |
2191 | \&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime, |
3764 | \&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime, |
2192 | otherwise another method will be used as fallback. This is the preferred |
3765 | otherwise another method will be used as fallback. This is the preferred |
… | |
… | |
2202 | 10 port style backend. Its availability will be detected at runtime, |
3775 | 10 port style backend. Its availability will be detected at runtime, |
2203 | otherwise another method will be used as fallback. This is the preferred |
3776 | otherwise another method will be used as fallback. This is the preferred |
2204 | backend for Solaris 10 systems. |
3777 | backend for Solaris 10 systems. |
2205 | .IP "\s-1EV_USE_DEVPOLL\s0" 4 |
3778 | .IP "\s-1EV_USE_DEVPOLL\s0" 4 |
2206 | .IX Item "EV_USE_DEVPOLL" |
3779 | .IX Item "EV_USE_DEVPOLL" |
2207 | reserved for future expansion, works like the \s-1USE\s0 symbols above. |
3780 | Reserved for future expansion, works like the \s-1USE\s0 symbols above. |
2208 | .IP "\s-1EV_USE_INOTIFY\s0" 4 |
3781 | .IP "\s-1EV_USE_INOTIFY\s0" 4 |
2209 | .IX Item "EV_USE_INOTIFY" |
3782 | .IX Item "EV_USE_INOTIFY" |
2210 | If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify |
3783 | If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify |
2211 | interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will |
3784 | interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will |
2212 | be detected at runtime. |
3785 | be detected at runtime. If undefined, it will be enabled if the headers |
|
|
3786 | indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
|
|
3787 | .IP "\s-1EV_ATOMIC_T\s0" 4 |
|
|
3788 | .IX Item "EV_ATOMIC_T" |
|
|
3789 | Libev requires an integer type (suitable for storing \f(CW0\fR or \f(CW1\fR) whose |
|
|
3790 | access is atomic with respect to other threads or signal contexts. No such |
|
|
3791 | type is easily found in the C language, so you can provide your own type |
|
|
3792 | that you know is safe for your purposes. It is used both for signal handler \*(L"locking\*(R" |
|
|
3793 | as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR watchers. |
|
|
3794 | .Sp |
|
|
3795 | In the absence of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR |
|
|
3796 | (from \fIsignal.h\fR), which is usually good enough on most platforms. |
2213 | .IP "\s-1EV_H\s0" 4 |
3797 | .IP "\s-1EV_H\s0" 4 |
2214 | .IX Item "EV_H" |
3798 | .IX Item "EV_H" |
2215 | The name of the \fIev.h\fR header file used to include it. The default if |
3799 | The name of the \fIev.h\fR header file used to include it. The default if |
2216 | undefined is \f(CW\*(C`<ev.h>\*(C'\fR in \fIevent.h\fR and \f(CW"ev.h"\fR in \fIev.c\fR. This |
3800 | undefined is \f(CW"ev.h"\fR in \fIevent.h\fR, \fIev.c\fR and \fIev++.h\fR. This can be |
2217 | can be used to virtually rename the \fIev.h\fR header file in case of conflicts. |
3801 | used to virtually rename the \fIev.h\fR header file in case of conflicts. |
2218 | .IP "\s-1EV_CONFIG_H\s0" 4 |
3802 | .IP "\s-1EV_CONFIG_H\s0" 4 |
2219 | .IX Item "EV_CONFIG_H" |
3803 | .IX Item "EV_CONFIG_H" |
2220 | If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override |
3804 | If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override |
2221 | \&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to |
3805 | \&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to |
2222 | \&\f(CW\*(C`EV_H\*(C'\fR, above. |
3806 | \&\f(CW\*(C`EV_H\*(C'\fR, above. |
2223 | .IP "\s-1EV_EVENT_H\s0" 4 |
3807 | .IP "\s-1EV_EVENT_H\s0" 4 |
2224 | .IX Item "EV_EVENT_H" |
3808 | .IX Item "EV_EVENT_H" |
2225 | Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea |
3809 | Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea |
2226 | of how the \fIevent.h\fR header can be found. |
3810 | of how the \fIevent.h\fR header can be found, the default is \f(CW"event.h"\fR. |
2227 | .IP "\s-1EV_PROTOTYPES\s0" 4 |
3811 | .IP "\s-1EV_PROTOTYPES\s0" 4 |
2228 | .IX Item "EV_PROTOTYPES" |
3812 | .IX Item "EV_PROTOTYPES" |
2229 | If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function |
3813 | If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function |
2230 | prototypes, but still define all the structs and other symbols. This is |
3814 | prototypes, but still define all the structs and other symbols. This is |
2231 | occasionally useful if you want to provide your own wrapper functions |
3815 | occasionally useful if you want to provide your own wrapper functions |
… | |
… | |
2235 | If undefined or defined to \f(CW1\fR, then all event-loop-specific functions |
3819 | If undefined or defined to \f(CW1\fR, then all event-loop-specific functions |
2236 | will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create |
3820 | will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create |
2237 | additional independent event loops. Otherwise there will be no support |
3821 | additional independent event loops. Otherwise there will be no support |
2238 | for multiple event loops and there is no first event loop pointer |
3822 | for multiple event loops and there is no first event loop pointer |
2239 | argument. Instead, all functions act on the single default loop. |
3823 | argument. Instead, all functions act on the single default loop. |
|
|
3824 | .IP "\s-1EV_MINPRI\s0" 4 |
|
|
3825 | .IX Item "EV_MINPRI" |
|
|
3826 | .PD 0 |
|
|
3827 | .IP "\s-1EV_MAXPRI\s0" 4 |
|
|
3828 | .IX Item "EV_MAXPRI" |
|
|
3829 | .PD |
|
|
3830 | The range of allowed priorities. \f(CW\*(C`EV_MINPRI\*(C'\fR must be smaller or equal to |
|
|
3831 | \&\f(CW\*(C`EV_MAXPRI\*(C'\fR, but otherwise there are no non-obvious limitations. You can |
|
|
3832 | provide for more priorities by overriding those symbols (usually defined |
|
|
3833 | to be \f(CW\*(C`\-2\*(C'\fR and \f(CW2\fR, respectively). |
|
|
3834 | .Sp |
|
|
3835 | When doing priority-based operations, libev usually has to linearly search |
|
|
3836 | all the priorities, so having many of them (hundreds) uses a lot of space |
|
|
3837 | and time, so using the defaults of five priorities (\-2 .. +2) is usually |
|
|
3838 | fine. |
|
|
3839 | .Sp |
|
|
3840 | If your embedding application does not need any priorities, defining these |
|
|
3841 | both to \f(CW0\fR will save some memory and \s-1CPU\s0. |
2240 | .IP "\s-1EV_PERIODIC_ENABLE\s0" 4 |
3842 | .IP "\s-1EV_PERIODIC_ENABLE\s0" 4 |
2241 | .IX Item "EV_PERIODIC_ENABLE" |
3843 | .IX Item "EV_PERIODIC_ENABLE" |
2242 | If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If |
3844 | If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If |
2243 | defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of |
3845 | defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of |
2244 | code. |
3846 | code. |
|
|
3847 | .IP "\s-1EV_IDLE_ENABLE\s0" 4 |
|
|
3848 | .IX Item "EV_IDLE_ENABLE" |
|
|
3849 | If undefined or defined to be \f(CW1\fR, then idle watchers are supported. If |
|
|
3850 | defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of |
|
|
3851 | code. |
2245 | .IP "\s-1EV_EMBED_ENABLE\s0" 4 |
3852 | .IP "\s-1EV_EMBED_ENABLE\s0" 4 |
2246 | .IX Item "EV_EMBED_ENABLE" |
3853 | .IX Item "EV_EMBED_ENABLE" |
2247 | If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If |
3854 | If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If |
2248 | defined to be \f(CW0\fR, then they are not. |
3855 | defined to be \f(CW0\fR, then they are not. Embed watchers rely on most other |
|
|
3856 | watcher types, which therefore must not be disabled. |
2249 | .IP "\s-1EV_STAT_ENABLE\s0" 4 |
3857 | .IP "\s-1EV_STAT_ENABLE\s0" 4 |
2250 | .IX Item "EV_STAT_ENABLE" |
3858 | .IX Item "EV_STAT_ENABLE" |
2251 | If undefined or defined to be \f(CW1\fR, then stat watchers are supported. If |
3859 | If undefined or defined to be \f(CW1\fR, then stat watchers are supported. If |
2252 | defined to be \f(CW0\fR, then they are not. |
3860 | defined to be \f(CW0\fR, then they are not. |
2253 | .IP "\s-1EV_FORK_ENABLE\s0" 4 |
3861 | .IP "\s-1EV_FORK_ENABLE\s0" 4 |
2254 | .IX Item "EV_FORK_ENABLE" |
3862 | .IX Item "EV_FORK_ENABLE" |
2255 | If undefined or defined to be \f(CW1\fR, then fork watchers are supported. If |
3863 | If undefined or defined to be \f(CW1\fR, then fork watchers are supported. If |
2256 | defined to be \f(CW0\fR, then they are not. |
3864 | defined to be \f(CW0\fR, then they are not. |
|
|
3865 | .IP "\s-1EV_ASYNC_ENABLE\s0" 4 |
|
|
3866 | .IX Item "EV_ASYNC_ENABLE" |
|
|
3867 | If undefined or defined to be \f(CW1\fR, then async watchers are supported. If |
|
|
3868 | defined to be \f(CW0\fR, then they are not. |
2257 | .IP "\s-1EV_MINIMAL\s0" 4 |
3869 | .IP "\s-1EV_MINIMAL\s0" 4 |
2258 | .IX Item "EV_MINIMAL" |
3870 | .IX Item "EV_MINIMAL" |
2259 | If you need to shave off some kilobytes of code at the expense of some |
3871 | If you need to shave off some kilobytes of code at the expense of some |
2260 | speed, define this symbol to \f(CW1\fR. Currently only used for gcc to override |
3872 | speed (but with the full \s-1API\s0), define this symbol to \f(CW1\fR. Currently this |
2261 | some inlining decisions, saves roughly 30% codesize of amd64. |
3873 | is used to override some inlining decisions, saves roughly 30% code size |
|
|
3874 | on amd64. It also selects a much smaller 2\-heap for timer management over |
|
|
3875 | the default 4\-heap. |
|
|
3876 | .Sp |
|
|
3877 | You can save even more by disabling watcher types you do not need |
|
|
3878 | and setting \f(CW\*(C`EV_MAXPRI\*(C'\fR == \f(CW\*(C`EV_MINPRI\*(C'\fR. Also, disabling \f(CW\*(C`assert\*(C'\fR |
|
|
3879 | (\f(CW\*(C`\-DNDEBUG\*(C'\fR) will usually reduce code size a lot. |
|
|
3880 | .Sp |
|
|
3881 | Defining \f(CW\*(C`EV_MINIMAL\*(C'\fR to \f(CW2\fR will additionally reduce the core \s-1API\s0 to |
|
|
3882 | provide a bare-bones event library. See \f(CW\*(C`ev.h\*(C'\fR for details on what parts |
|
|
3883 | of the \s-1API\s0 are still available, and do not complain if this subset changes |
|
|
3884 | over time. |
2262 | .IP "\s-1EV_PID_HASHSIZE\s0" 4 |
3885 | .IP "\s-1EV_PID_HASHSIZE\s0" 4 |
2263 | .IX Item "EV_PID_HASHSIZE" |
3886 | .IX Item "EV_PID_HASHSIZE" |
2264 | \&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by |
3887 | \&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by |
2265 | pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more |
3888 | pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more |
2266 | than enough. If you need to manage thousands of children you might want to |
3889 | than enough. If you need to manage thousands of children you might want to |
2267 | increase this value (\fImust\fR be a power of two). |
3890 | increase this value (\fImust\fR be a power of two). |
2268 | .IP "\s-1EV_INOTIFY_HASHSIZE\s0" 4 |
3891 | .IP "\s-1EV_INOTIFY_HASHSIZE\s0" 4 |
2269 | .IX Item "EV_INOTIFY_HASHSIZE" |
3892 | .IX Item "EV_INOTIFY_HASHSIZE" |
2270 | \&\f(CW\*(C`ev_staz\*(C'\fR watchers use a small hash table to distribute workload by |
3893 | \&\f(CW\*(C`ev_stat\*(C'\fR watchers use a small hash table to distribute workload by |
2271 | inotify watch id. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), |
3894 | inotify watch id. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), |
2272 | usually more than enough. If you need to manage thousands of \f(CW\*(C`ev_stat\*(C'\fR |
3895 | usually more than enough. If you need to manage thousands of \f(CW\*(C`ev_stat\*(C'\fR |
2273 | watchers you might want to increase this value (\fImust\fR be a power of |
3896 | watchers you might want to increase this value (\fImust\fR be a power of |
2274 | two). |
3897 | two). |
|
|
3898 | .IP "\s-1EV_USE_4HEAP\s0" 4 |
|
|
3899 | .IX Item "EV_USE_4HEAP" |
|
|
3900 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
|
|
3901 | timer and periodics heaps, libev uses a 4\-heap when this symbol is defined |
|
|
3902 | to \f(CW1\fR. The 4\-heap uses more complicated (longer) code but has noticeably |
|
|
3903 | faster performance with many (thousands) of watchers. |
|
|
3904 | .Sp |
|
|
3905 | The default is \f(CW1\fR unless \f(CW\*(C`EV_MINIMAL\*(C'\fR is set in which case it is \f(CW0\fR |
|
|
3906 | (disabled). |
|
|
3907 | .IP "\s-1EV_HEAP_CACHE_AT\s0" 4 |
|
|
3908 | .IX Item "EV_HEAP_CACHE_AT" |
|
|
3909 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
|
|
3910 | timer and periodics heaps, libev can cache the timestamp (\fIat\fR) within |
|
|
3911 | the heap structure (selected by defining \f(CW\*(C`EV_HEAP_CACHE_AT\*(C'\fR to \f(CW1\fR), |
|
|
3912 | which uses 8\-12 bytes more per watcher and a few hundred bytes more code, |
|
|
3913 | but avoids random read accesses on heap changes. This improves performance |
|
|
3914 | noticeably with many (hundreds) of watchers. |
|
|
3915 | .Sp |
|
|
3916 | The default is \f(CW1\fR unless \f(CW\*(C`EV_MINIMAL\*(C'\fR is set in which case it is \f(CW0\fR |
|
|
3917 | (disabled). |
|
|
3918 | .IP "\s-1EV_VERIFY\s0" 4 |
|
|
3919 | .IX Item "EV_VERIFY" |
|
|
3920 | Controls how much internal verification (see \f(CW\*(C`ev_loop_verify ()\*(C'\fR) will |
|
|
3921 | be done: If set to \f(CW0\fR, no internal verification code will be compiled |
|
|
3922 | in. If set to \f(CW1\fR, then verification code will be compiled in, but not |
|
|
3923 | called. If set to \f(CW2\fR, then the internal verification code will be |
|
|
3924 | called once per loop, which can slow down libev. If set to \f(CW3\fR, then the |
|
|
3925 | verification code will be called very frequently, which will slow down |
|
|
3926 | libev considerably. |
|
|
3927 | .Sp |
|
|
3928 | The default is \f(CW1\fR, unless \f(CW\*(C`EV_MINIMAL\*(C'\fR is set, in which case it will be |
|
|
3929 | \&\f(CW0\fR. |
2275 | .IP "\s-1EV_COMMON\s0" 4 |
3930 | .IP "\s-1EV_COMMON\s0" 4 |
2276 | .IX Item "EV_COMMON" |
3931 | .IX Item "EV_COMMON" |
2277 | By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining |
3932 | By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining |
2278 | this macro to a something else you can include more and other types of |
3933 | this macro to a something else you can include more and other types of |
2279 | members. You have to define it each time you include one of the files, |
3934 | members. You have to define it each time you include one of the files, |
2280 | though, and it must be identical each time. |
3935 | though, and it must be identical each time. |
2281 | .Sp |
3936 | .Sp |
2282 | For example, the perl \s-1EV\s0 module uses something like this: |
3937 | For example, the perl \s-1EV\s0 module uses something like this: |
2283 | .Sp |
3938 | .Sp |
2284 | .Vb 3 |
3939 | .Vb 3 |
2285 | \& #define EV_COMMON \e |
3940 | \& #define EV_COMMON \e |
2286 | \& SV *self; /* contains this struct */ \e |
3941 | \& SV *self; /* contains this struct */ \e |
2287 | \& SV *cb_sv, *fh /* note no trailing ";" */ |
3942 | \& SV *cb_sv, *fh /* note no trailing ";" */ |
2288 | .Ve |
3943 | .Ve |
2289 | .IP "\s-1EV_CB_DECLARE\s0 (type)" 4 |
3944 | .IP "\s-1EV_CB_DECLARE\s0 (type)" 4 |
2290 | .IX Item "EV_CB_DECLARE (type)" |
3945 | .IX Item "EV_CB_DECLARE (type)" |
2291 | .PD 0 |
3946 | .PD 0 |
2292 | .IP "\s-1EV_CB_INVOKE\s0 (watcher, revents)" 4 |
3947 | .IP "\s-1EV_CB_INVOKE\s0 (watcher, revents)" 4 |
… | |
… | |
2294 | .IP "ev_set_cb (ev, cb)" 4 |
3949 | .IP "ev_set_cb (ev, cb)" 4 |
2295 | .IX Item "ev_set_cb (ev, cb)" |
3950 | .IX Item "ev_set_cb (ev, cb)" |
2296 | .PD |
3951 | .PD |
2297 | Can be used to change the callback member declaration in each watcher, |
3952 | Can be used to change the callback member declaration in each watcher, |
2298 | and the way callbacks are invoked and set. Must expand to a struct member |
3953 | and the way callbacks are invoked and set. Must expand to a struct member |
2299 | definition and a statement, respectively. See the \fIev.v\fR header file for |
3954 | definition and a statement, respectively. See the \fIev.h\fR header file for |
2300 | their default definitions. One possible use for overriding these is to |
3955 | their default definitions. One possible use for overriding these is to |
2301 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
3956 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
2302 | method calls instead of plain function calls in \*(C+. |
3957 | method calls instead of plain function calls in \*(C+. |
|
|
3958 | .SS "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0" |
|
|
3959 | .IX Subsection "EXPORTED API SYMBOLS" |
|
|
3960 | If you need to re-export the \s-1API\s0 (e.g. via a \s-1DLL\s0) and you need a list of |
|
|
3961 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
|
|
3962 | all public symbols, one per line: |
|
|
3963 | .PP |
|
|
3964 | .Vb 2 |
|
|
3965 | \& Symbols.ev for libev proper |
|
|
3966 | \& Symbols.event for the libevent emulation |
|
|
3967 | .Ve |
|
|
3968 | .PP |
|
|
3969 | This can also be used to rename all public symbols to avoid clashes with |
|
|
3970 | multiple versions of libev linked together (which is obviously bad in |
|
|
3971 | itself, but sometimes it is inconvenient to avoid this). |
|
|
3972 | .PP |
|
|
3973 | A sed command like this will create wrapper \f(CW\*(C`#define\*(C'\fR's that you need to |
|
|
3974 | include before including \fIev.h\fR: |
|
|
3975 | .PP |
|
|
3976 | .Vb 1 |
|
|
3977 | \& <Symbols.ev sed \-e "s/.*/#define & myprefix_&/" >wrap.h |
|
|
3978 | .Ve |
|
|
3979 | .PP |
|
|
3980 | This would create a file \fIwrap.h\fR which essentially looks like this: |
|
|
3981 | .PP |
|
|
3982 | .Vb 4 |
|
|
3983 | \& #define ev_backend myprefix_ev_backend |
|
|
3984 | \& #define ev_check_start myprefix_ev_check_start |
|
|
3985 | \& #define ev_check_stop myprefix_ev_check_stop |
|
|
3986 | \& ... |
|
|
3987 | .Ve |
2303 | .Sh "\s-1EXAMPLES\s0" |
3988 | .SS "\s-1EXAMPLES\s0" |
2304 | .IX Subsection "EXAMPLES" |
3989 | .IX Subsection "EXAMPLES" |
2305 | For a real-world example of a program the includes libev |
3990 | For a real-world example of a program the includes libev |
2306 | verbatim, you can have a look at the \s-1EV\s0 perl module |
3991 | verbatim, you can have a look at the \s-1EV\s0 perl module |
2307 | (<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
3992 | (<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
2308 | the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public |
3993 | the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public |
2309 | interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file |
3994 | interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file |
2310 | will be compiled. It is pretty complex because it provides its own header |
3995 | will be compiled. It is pretty complex because it provides its own header |
2311 | file. |
3996 | file. |
2312 | .Sp |
3997 | .PP |
2313 | The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file |
3998 | The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file |
2314 | that everybody includes and which overrides some configure choices: |
3999 | that everybody includes and which overrides some configure choices: |
2315 | .Sp |
4000 | .PP |
2316 | .Vb 9 |
4001 | .Vb 9 |
2317 | \& #define EV_MINIMAL 1 |
4002 | \& #define EV_MINIMAL 1 |
2318 | \& #define EV_USE_POLL 0 |
4003 | \& #define EV_USE_POLL 0 |
2319 | \& #define EV_MULTIPLICITY 0 |
4004 | \& #define EV_MULTIPLICITY 0 |
2320 | \& #define EV_PERIODIC_ENABLE 0 |
4005 | \& #define EV_PERIODIC_ENABLE 0 |
2321 | \& #define EV_STAT_ENABLE 0 |
4006 | \& #define EV_STAT_ENABLE 0 |
2322 | \& #define EV_FORK_ENABLE 0 |
4007 | \& #define EV_FORK_ENABLE 0 |
2323 | \& #define EV_CONFIG_H <config.h> |
4008 | \& #define EV_CONFIG_H <config.h> |
2324 | \& #define EV_MINPRI 0 |
4009 | \& #define EV_MINPRI 0 |
2325 | \& #define EV_MAXPRI 0 |
4010 | \& #define EV_MAXPRI 0 |
2326 | .Ve |
4011 | \& |
2327 | .Sp |
|
|
2328 | .Vb 1 |
|
|
2329 | \& #include "ev++.h" |
4012 | \& #include "ev++.h" |
2330 | .Ve |
4013 | .Ve |
2331 | .Sp |
4014 | .PP |
2332 | And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled: |
4015 | And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled: |
2333 | .Sp |
4016 | .PP |
2334 | .Vb 2 |
4017 | .Vb 2 |
2335 | \& #include "ev_cpp.h" |
4018 | \& #include "ev_cpp.h" |
2336 | \& #include "ev.c" |
4019 | \& #include "ev.c" |
2337 | .Ve |
4020 | .Ve |
|
|
4021 | .SH "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES" |
|
|
4022 | .IX Header "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES" |
|
|
4023 | .SS "\s-1THREADS\s0 \s-1AND\s0 \s-1COROUTINES\s0" |
|
|
4024 | .IX Subsection "THREADS AND COROUTINES" |
|
|
4025 | \fI\s-1THREADS\s0\fR |
|
|
4026 | .IX Subsection "THREADS" |
|
|
4027 | .PP |
|
|
4028 | All libev functions are reentrant and thread-safe unless explicitly |
|
|
4029 | documented otherwise, but libev implements no locking itself. This means |
|
|
4030 | that you can use as many loops as you want in parallel, as long as there |
|
|
4031 | are no concurrent calls into any libev function with the same loop |
|
|
4032 | parameter (\f(CW\*(C`ev_default_*\*(C'\fR calls have an implicit default loop parameter, |
|
|
4033 | of course): libev guarantees that different event loops share no data |
|
|
4034 | structures that need any locking. |
|
|
4035 | .PP |
|
|
4036 | Or to put it differently: calls with different loop parameters can be done |
|
|
4037 | concurrently from multiple threads, calls with the same loop parameter |
|
|
4038 | must be done serially (but can be done from different threads, as long as |
|
|
4039 | only one thread ever is inside a call at any point in time, e.g. by using |
|
|
4040 | a mutex per loop). |
|
|
4041 | .PP |
|
|
4042 | Specifically to support threads (and signal handlers), libev implements |
|
|
4043 | so-called \f(CW\*(C`ev_async\*(C'\fR watchers, which allow some limited form of |
|
|
4044 | concurrency on the same event loop, namely waking it up \*(L"from the |
|
|
4045 | outside\*(R". |
|
|
4046 | .PP |
|
|
4047 | If you want to know which design (one loop, locking, or multiple loops |
|
|
4048 | without or something else still) is best for your problem, then I cannot |
|
|
4049 | help you, but here is some generic advice: |
|
|
4050 | .IP "\(bu" 4 |
|
|
4051 | most applications have a main thread: use the default libev loop |
|
|
4052 | in that thread, or create a separate thread running only the default loop. |
|
|
4053 | .Sp |
|
|
4054 | This helps integrating other libraries or software modules that use libev |
|
|
4055 | themselves and don't care/know about threading. |
|
|
4056 | .IP "\(bu" 4 |
|
|
4057 | one loop per thread is usually a good model. |
|
|
4058 | .Sp |
|
|
4059 | Doing this is almost never wrong, sometimes a better-performance model |
|
|
4060 | exists, but it is always a good start. |
|
|
4061 | .IP "\(bu" 4 |
|
|
4062 | other models exist, such as the leader/follower pattern, where one |
|
|
4063 | loop is handed through multiple threads in a kind of round-robin fashion. |
|
|
4064 | .Sp |
|
|
4065 | Choosing a model is hard \- look around, learn, know that usually you can do |
|
|
4066 | better than you currently do :\-) |
|
|
4067 | .IP "\(bu" 4 |
|
|
4068 | often you need to talk to some other thread which blocks in the |
|
|
4069 | event loop. |
|
|
4070 | .Sp |
|
|
4071 | \&\f(CW\*(C`ev_async\*(C'\fR watchers can be used to wake them up from other threads safely |
|
|
4072 | (or from signal contexts...). |
|
|
4073 | .Sp |
|
|
4074 | An example use would be to communicate signals or other events that only |
|
|
4075 | work in the default loop by registering the signal watcher with the |
|
|
4076 | default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop |
|
|
4077 | watcher callback into the event loop interested in the signal. |
|
|
4078 | .PP |
|
|
4079 | \s-1THREAD\s0 \s-1LOCKING\s0 \s-1EXAMPLE\s0 |
|
|
4080 | .IX Subsection "THREAD LOCKING EXAMPLE" |
|
|
4081 | .PP |
|
|
4082 | Here is a fictitious example of how to run an event loop in a different |
|
|
4083 | thread than where callbacks are being invoked and watchers are |
|
|
4084 | created/added/removed. |
|
|
4085 | .PP |
|
|
4086 | For a real-world example, see the \f(CW\*(C`EV::Loop::Async\*(C'\fR perl module, |
|
|
4087 | which uses exactly this technique (which is suited for many high-level |
|
|
4088 | languages). |
|
|
4089 | .PP |
|
|
4090 | The example uses a pthread mutex to protect the loop data, a condition |
|
|
4091 | variable to wait for callback invocations, an async watcher to notify the |
|
|
4092 | event loop thread and an unspecified mechanism to wake up the main thread. |
|
|
4093 | .PP |
|
|
4094 | First, you need to associate some data with the event loop: |
|
|
4095 | .PP |
|
|
4096 | .Vb 6 |
|
|
4097 | \& typedef struct { |
|
|
4098 | \& mutex_t lock; /* global loop lock */ |
|
|
4099 | \& ev_async async_w; |
|
|
4100 | \& thread_t tid; |
|
|
4101 | \& cond_t invoke_cv; |
|
|
4102 | \& } userdata; |
|
|
4103 | \& |
|
|
4104 | \& void prepare_loop (EV_P) |
|
|
4105 | \& { |
|
|
4106 | \& // for simplicity, we use a static userdata struct. |
|
|
4107 | \& static userdata u; |
|
|
4108 | \& |
|
|
4109 | \& ev_async_init (&u\->async_w, async_cb); |
|
|
4110 | \& ev_async_start (EV_A_ &u\->async_w); |
|
|
4111 | \& |
|
|
4112 | \& pthread_mutex_init (&u\->lock, 0); |
|
|
4113 | \& pthread_cond_init (&u\->invoke_cv, 0); |
|
|
4114 | \& |
|
|
4115 | \& // now associate this with the loop |
|
|
4116 | \& ev_set_userdata (EV_A_ u); |
|
|
4117 | \& ev_set_invoke_pending_cb (EV_A_ l_invoke); |
|
|
4118 | \& ev_set_loop_release_cb (EV_A_ l_release, l_acquire); |
|
|
4119 | \& |
|
|
4120 | \& // then create the thread running ev_loop |
|
|
4121 | \& pthread_create (&u\->tid, 0, l_run, EV_A); |
|
|
4122 | \& } |
|
|
4123 | .Ve |
|
|
4124 | .PP |
|
|
4125 | The callback for the \f(CW\*(C`ev_async\*(C'\fR watcher does nothing: the watcher is used |
|
|
4126 | solely to wake up the event loop so it takes notice of any new watchers |
|
|
4127 | that might have been added: |
|
|
4128 | .PP |
|
|
4129 | .Vb 5 |
|
|
4130 | \& static void |
|
|
4131 | \& async_cb (EV_P_ ev_async *w, int revents) |
|
|
4132 | \& { |
|
|
4133 | \& // just used for the side effects |
|
|
4134 | \& } |
|
|
4135 | .Ve |
|
|
4136 | .PP |
|
|
4137 | The \f(CW\*(C`l_release\*(C'\fR and \f(CW\*(C`l_acquire\*(C'\fR callbacks simply unlock/lock the mutex |
|
|
4138 | protecting the loop data, respectively. |
|
|
4139 | .PP |
|
|
4140 | .Vb 6 |
|
|
4141 | \& static void |
|
|
4142 | \& l_release (EV_P) |
|
|
4143 | \& { |
|
|
4144 | \& userdata *u = ev_userdata (EV_A); |
|
|
4145 | \& pthread_mutex_unlock (&u\->lock); |
|
|
4146 | \& } |
|
|
4147 | \& |
|
|
4148 | \& static void |
|
|
4149 | \& l_acquire (EV_P) |
|
|
4150 | \& { |
|
|
4151 | \& userdata *u = ev_userdata (EV_A); |
|
|
4152 | \& pthread_mutex_lock (&u\->lock); |
|
|
4153 | \& } |
|
|
4154 | .Ve |
|
|
4155 | .PP |
|
|
4156 | The event loop thread first acquires the mutex, and then jumps straight |
|
|
4157 | into \f(CW\*(C`ev_loop\*(C'\fR: |
|
|
4158 | .PP |
|
|
4159 | .Vb 4 |
|
|
4160 | \& void * |
|
|
4161 | \& l_run (void *thr_arg) |
|
|
4162 | \& { |
|
|
4163 | \& struct ev_loop *loop = (struct ev_loop *)thr_arg; |
|
|
4164 | \& |
|
|
4165 | \& l_acquire (EV_A); |
|
|
4166 | \& pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
|
|
4167 | \& ev_loop (EV_A_ 0); |
|
|
4168 | \& l_release (EV_A); |
|
|
4169 | \& |
|
|
4170 | \& return 0; |
|
|
4171 | \& } |
|
|
4172 | .Ve |
|
|
4173 | .PP |
|
|
4174 | Instead of invoking all pending watchers, the \f(CW\*(C`l_invoke\*(C'\fR callback will |
|
|
4175 | signal the main thread via some unspecified mechanism (signals? pipe |
|
|
4176 | writes? \f(CW\*(C`Async::Interrupt\*(C'\fR?) and then waits until all pending watchers |
|
|
4177 | have been called (in a while loop because a) spurious wakeups are possible |
|
|
4178 | and b) skipping inter-thread-communication when there are no pending |
|
|
4179 | watchers is very beneficial): |
|
|
4180 | .PP |
|
|
4181 | .Vb 4 |
|
|
4182 | \& static void |
|
|
4183 | \& l_invoke (EV_P) |
|
|
4184 | \& { |
|
|
4185 | \& userdata *u = ev_userdata (EV_A); |
|
|
4186 | \& |
|
|
4187 | \& while (ev_pending_count (EV_A)) |
|
|
4188 | \& { |
|
|
4189 | \& wake_up_other_thread_in_some_magic_or_not_so_magic_way (); |
|
|
4190 | \& pthread_cond_wait (&u\->invoke_cv, &u\->lock); |
|
|
4191 | \& } |
|
|
4192 | \& } |
|
|
4193 | .Ve |
|
|
4194 | .PP |
|
|
4195 | Now, whenever the main thread gets told to invoke pending watchers, it |
|
|
4196 | will grab the lock, call \f(CW\*(C`ev_invoke_pending\*(C'\fR and then signal the loop |
|
|
4197 | thread to continue: |
|
|
4198 | .PP |
|
|
4199 | .Vb 4 |
|
|
4200 | \& static void |
|
|
4201 | \& real_invoke_pending (EV_P) |
|
|
4202 | \& { |
|
|
4203 | \& userdata *u = ev_userdata (EV_A); |
|
|
4204 | \& |
|
|
4205 | \& pthread_mutex_lock (&u\->lock); |
|
|
4206 | \& ev_invoke_pending (EV_A); |
|
|
4207 | \& pthread_cond_signal (&u\->invoke_cv); |
|
|
4208 | \& pthread_mutex_unlock (&u\->lock); |
|
|
4209 | \& } |
|
|
4210 | .Ve |
|
|
4211 | .PP |
|
|
4212 | Whenever you want to start/stop a watcher or do other modifications to an |
|
|
4213 | event loop, you will now have to lock: |
|
|
4214 | .PP |
|
|
4215 | .Vb 2 |
|
|
4216 | \& ev_timer timeout_watcher; |
|
|
4217 | \& userdata *u = ev_userdata (EV_A); |
|
|
4218 | \& |
|
|
4219 | \& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
|
|
4220 | \& |
|
|
4221 | \& pthread_mutex_lock (&u\->lock); |
|
|
4222 | \& ev_timer_start (EV_A_ &timeout_watcher); |
|
|
4223 | \& ev_async_send (EV_A_ &u\->async_w); |
|
|
4224 | \& pthread_mutex_unlock (&u\->lock); |
|
|
4225 | .Ve |
|
|
4226 | .PP |
|
|
4227 | Note that sending the \f(CW\*(C`ev_async\*(C'\fR watcher is required because otherwise |
|
|
4228 | an event loop currently blocking in the kernel will have no knowledge |
|
|
4229 | about the newly added timer. By waking up the loop it will pick up any new |
|
|
4230 | watchers in the next event loop iteration. |
|
|
4231 | .PP |
|
|
4232 | \fI\s-1COROUTINES\s0\fR |
|
|
4233 | .IX Subsection "COROUTINES" |
|
|
4234 | .PP |
|
|
4235 | Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"): |
|
|
4236 | libev fully supports nesting calls to its functions from different |
|
|
4237 | coroutines (e.g. you can call \f(CW\*(C`ev_loop\*(C'\fR on the same loop from two |
|
|
4238 | different coroutines, and switch freely between both coroutines running |
|
|
4239 | the loop, as long as you don't confuse yourself). The only exception is |
|
|
4240 | that you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. |
|
|
4241 | .PP |
|
|
4242 | Care has been taken to ensure that libev does not keep local state inside |
|
|
4243 | \&\f(CW\*(C`ev_loop\*(C'\fR, and other calls do not usually allow for coroutine switches as |
|
|
4244 | they do not call any callbacks. |
|
|
4245 | .SS "\s-1COMPILER\s0 \s-1WARNINGS\s0" |
|
|
4246 | .IX Subsection "COMPILER WARNINGS" |
|
|
4247 | Depending on your compiler and compiler settings, you might get no or a |
|
|
4248 | lot of warnings when compiling libev code. Some people are apparently |
|
|
4249 | scared by this. |
|
|
4250 | .PP |
|
|
4251 | However, these are unavoidable for many reasons. For one, each compiler |
|
|
4252 | has different warnings, and each user has different tastes regarding |
|
|
4253 | warning options. \*(L"Warn-free\*(R" code therefore cannot be a goal except when |
|
|
4254 | targeting a specific compiler and compiler-version. |
|
|
4255 | .PP |
|
|
4256 | Another reason is that some compiler warnings require elaborate |
|
|
4257 | workarounds, or other changes to the code that make it less clear and less |
|
|
4258 | maintainable. |
|
|
4259 | .PP |
|
|
4260 | And of course, some compiler warnings are just plain stupid, or simply |
|
|
4261 | wrong (because they don't actually warn about the condition their message |
|
|
4262 | seems to warn about). For example, certain older gcc versions had some |
|
|
4263 | warnings that resulted an extreme number of false positives. These have |
|
|
4264 | been fixed, but some people still insist on making code warn-free with |
|
|
4265 | such buggy versions. |
|
|
4266 | .PP |
|
|
4267 | While libev is written to generate as few warnings as possible, |
|
|
4268 | \&\*(L"warn-free\*(R" code is not a goal, and it is recommended not to build libev |
|
|
4269 | with any compiler warnings enabled unless you are prepared to cope with |
|
|
4270 | them (e.g. by ignoring them). Remember that warnings are just that: |
|
|
4271 | warnings, not errors, or proof of bugs. |
|
|
4272 | .SS "\s-1VALGRIND\s0" |
|
|
4273 | .IX Subsection "VALGRIND" |
|
|
4274 | Valgrind has a special section here because it is a popular tool that is |
|
|
4275 | highly useful. Unfortunately, valgrind reports are very hard to interpret. |
|
|
4276 | .PP |
|
|
4277 | If you think you found a bug (memory leak, uninitialised data access etc.) |
|
|
4278 | in libev, then check twice: If valgrind reports something like: |
|
|
4279 | .PP |
|
|
4280 | .Vb 3 |
|
|
4281 | \& ==2274== definitely lost: 0 bytes in 0 blocks. |
|
|
4282 | \& ==2274== possibly lost: 0 bytes in 0 blocks. |
|
|
4283 | \& ==2274== still reachable: 256 bytes in 1 blocks. |
|
|
4284 | .Ve |
|
|
4285 | .PP |
|
|
4286 | Then there is no memory leak, just as memory accounted to global variables |
|
|
4287 | is not a memleak \- the memory is still being referenced, and didn't leak. |
|
|
4288 | .PP |
|
|
4289 | Similarly, under some circumstances, valgrind might report kernel bugs |
|
|
4290 | as if it were a bug in libev (e.g. in realloc or in the poll backend, |
|
|
4291 | although an acceptable workaround has been found here), or it might be |
|
|
4292 | confused. |
|
|
4293 | .PP |
|
|
4294 | Keep in mind that valgrind is a very good tool, but only a tool. Don't |
|
|
4295 | make it into some kind of religion. |
|
|
4296 | .PP |
|
|
4297 | If you are unsure about something, feel free to contact the mailing list |
|
|
4298 | with the full valgrind report and an explanation on why you think this |
|
|
4299 | is a bug in libev (best check the archives, too :). However, don't be |
|
|
4300 | annoyed when you get a brisk \*(L"this is no bug\*(R" answer and take the chance |
|
|
4301 | of learning how to interpret valgrind properly. |
|
|
4302 | .PP |
|
|
4303 | If you need, for some reason, empty reports from valgrind for your project |
|
|
4304 | I suggest using suppression lists. |
|
|
4305 | .SH "PORTABILITY NOTES" |
|
|
4306 | .IX Header "PORTABILITY NOTES" |
|
|
4307 | .SS "\s-1WIN32\s0 \s-1PLATFORM\s0 \s-1LIMITATIONS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" |
|
|
4308 | .IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS" |
|
|
4309 | Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev |
|
|
4310 | requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 |
|
|
4311 | model. Libev still offers limited functionality on this platform in |
|
|
4312 | the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket |
|
|
4313 | descriptors. This only applies when using Win32 natively, not when using |
|
|
4314 | e.g. cygwin. |
|
|
4315 | .PP |
|
|
4316 | Lifting these limitations would basically require the full |
|
|
4317 | re-implementation of the I/O system. If you are into these kinds of |
|
|
4318 | things, then note that glib does exactly that for you in a very portable |
|
|
4319 | way (note also that glib is the slowest event library known to man). |
|
|
4320 | .PP |
|
|
4321 | There is no supported compilation method available on windows except |
|
|
4322 | embedding it into other applications. |
|
|
4323 | .PP |
|
|
4324 | Sensible signal handling is officially unsupported by Microsoft \- libev |
|
|
4325 | tries its best, but under most conditions, signals will simply not work. |
|
|
4326 | .PP |
|
|
4327 | Not a libev limitation but worth mentioning: windows apparently doesn't |
|
|
4328 | accept large writes: instead of resulting in a partial write, windows will |
|
|
4329 | either accept everything or return \f(CW\*(C`ENOBUFS\*(C'\fR if the buffer is too large, |
|
|
4330 | so make sure you only write small amounts into your sockets (less than a |
|
|
4331 | megabyte seems safe, but this apparently depends on the amount of memory |
|
|
4332 | available). |
|
|
4333 | .PP |
|
|
4334 | Due to the many, low, and arbitrary limits on the win32 platform and |
|
|
4335 | the abysmal performance of winsockets, using a large number of sockets |
|
|
4336 | is not recommended (and not reasonable). If your program needs to use |
|
|
4337 | more than a hundred or so sockets, then likely it needs to use a totally |
|
|
4338 | different implementation for windows, as libev offers the \s-1POSIX\s0 readiness |
|
|
4339 | notification model, which cannot be implemented efficiently on windows |
|
|
4340 | (due to Microsoft monopoly games). |
|
|
4341 | .PP |
|
|
4342 | A typical way to use libev under windows is to embed it (see the embedding |
|
|
4343 | section for details) and use the following \fIevwrap.h\fR header file instead |
|
|
4344 | of \fIev.h\fR: |
|
|
4345 | .PP |
|
|
4346 | .Vb 2 |
|
|
4347 | \& #define EV_STANDALONE /* keeps ev from requiring config.h */ |
|
|
4348 | \& #define EV_SELECT_IS_WINSOCKET 1 /* configure libev for windows select */ |
|
|
4349 | \& |
|
|
4350 | \& #include "ev.h" |
|
|
4351 | .Ve |
|
|
4352 | .PP |
|
|
4353 | And compile the following \fIevwrap.c\fR file into your project (make sure |
|
|
4354 | you do \fInot\fR compile the \fIev.c\fR or any other embedded source files!): |
|
|
4355 | .PP |
|
|
4356 | .Vb 2 |
|
|
4357 | \& #include "evwrap.h" |
|
|
4358 | \& #include "ev.c" |
|
|
4359 | .Ve |
|
|
4360 | .IP "The winsocket select function" 4 |
|
|
4361 | .IX Item "The winsocket select function" |
|
|
4362 | The winsocket \f(CW\*(C`select\*(C'\fR function doesn't follow \s-1POSIX\s0 in that it |
|
|
4363 | requires socket \fIhandles\fR and not socket \fIfile descriptors\fR (it is |
|
|
4364 | also extremely buggy). This makes select very inefficient, and also |
|
|
4365 | requires a mapping from file descriptors to socket handles (the Microsoft |
|
|
4366 | C runtime provides the function \f(CW\*(C`_open_osfhandle\*(C'\fR for this). See the |
|
|
4367 | discussion of the \f(CW\*(C`EV_SELECT_USE_FD_SET\*(C'\fR, \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR and |
|
|
4368 | \&\f(CW\*(C`EV_FD_TO_WIN32_HANDLE\*(C'\fR preprocessor symbols for more info. |
|
|
4369 | .Sp |
|
|
4370 | The configuration for a \*(L"naked\*(R" win32 using the Microsoft runtime |
|
|
4371 | libraries and raw winsocket select is: |
|
|
4372 | .Sp |
|
|
4373 | .Vb 2 |
|
|
4374 | \& #define EV_USE_SELECT 1 |
|
|
4375 | \& #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
|
|
4376 | .Ve |
|
|
4377 | .Sp |
|
|
4378 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
|
|
4379 | complexity in the O(nA\*^X) range when using win32. |
|
|
4380 | .IP "Limited number of file descriptors" 4 |
|
|
4381 | .IX Item "Limited number of file descriptors" |
|
|
4382 | Windows has numerous arbitrary (and low) limits on things. |
|
|
4383 | .Sp |
|
|
4384 | Early versions of winsocket's select only supported waiting for a maximum |
|
|
4385 | of \f(CW64\fR handles (probably owning to the fact that all windows kernels |
|
|
4386 | can only wait for \f(CW64\fR things at the same time internally; Microsoft |
|
|
4387 | recommends spawning a chain of threads and wait for 63 handles and the |
|
|
4388 | previous thread in each. Sounds great!). |
|
|
4389 | .Sp |
|
|
4390 | Newer versions support more handles, but you need to define \f(CW\*(C`FD_SETSIZE\*(C'\fR |
|
|
4391 | to some high number (e.g. \f(CW2048\fR) before compiling the winsocket select |
|
|
4392 | call (which might be in libev or elsewhere, for example, perl and many |
|
|
4393 | other interpreters do their own select emulation on windows). |
|
|
4394 | .Sp |
|
|
4395 | Another limit is the number of file descriptors in the Microsoft runtime |
|
|
4396 | libraries, which by default is \f(CW64\fR (there must be a hidden \fI64\fR |
|
|
4397 | fetish or something like this inside Microsoft). You can increase this |
|
|
4398 | by calling \f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR |
|
|
4399 | (another arbitrary limit), but is broken in many versions of the Microsoft |
|
|
4400 | runtime libraries. This might get you to about \f(CW512\fR or \f(CW2048\fR sockets |
|
|
4401 | (depending on windows version and/or the phase of the moon). To get more, |
|
|
4402 | you need to wrap all I/O functions and provide your own fd management, but |
|
|
4403 | the cost of calling select (O(nA\*^X)) will likely make this unworkable. |
|
|
4404 | .SS "\s-1PORTABILITY\s0 \s-1REQUIREMENTS\s0" |
|
|
4405 | .IX Subsection "PORTABILITY REQUIREMENTS" |
|
|
4406 | In addition to a working ISO-C implementation and of course the |
|
|
4407 | backend-specific APIs, libev relies on a few additional extensions: |
|
|
4408 | .ie n .IP """void (*)(ev_watcher_type *, int revents)"" must have compatible calling conventions regardless of ""ev_watcher_type *""." 4 |
|
|
4409 | .el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4 |
|
|
4410 | .IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *." |
|
|
4411 | Libev assumes not only that all watcher pointers have the same internal |
|
|
4412 | structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO\s0 C for example), but it also |
|
|
4413 | assumes that the same (machine) code can be used to call any watcher |
|
|
4414 | callback: The watcher callbacks have different type signatures, but libev |
|
|
4415 | calls them using an \f(CW\*(C`ev_watcher *\*(C'\fR internally. |
|
|
4416 | .ie n .IP """sig_atomic_t volatile"" must be thread-atomic as well" 4 |
|
|
4417 | .el .IP "\f(CWsig_atomic_t volatile\fR must be thread-atomic as well" 4 |
|
|
4418 | .IX Item "sig_atomic_t volatile must be thread-atomic as well" |
|
|
4419 | The type \f(CW\*(C`sig_atomic_t volatile\*(C'\fR (or whatever is defined as |
|
|
4420 | \&\f(CW\*(C`EV_ATOMIC_T\*(C'\fR) must be atomic with respect to accesses from different |
|
|
4421 | threads. This is not part of the specification for \f(CW\*(C`sig_atomic_t\*(C'\fR, but is |
|
|
4422 | believed to be sufficiently portable. |
|
|
4423 | .ie n .IP """sigprocmask"" must work in a threaded environment" 4 |
|
|
4424 | .el .IP "\f(CWsigprocmask\fR must work in a threaded environment" 4 |
|
|
4425 | .IX Item "sigprocmask must work in a threaded environment" |
|
|
4426 | Libev uses \f(CW\*(C`sigprocmask\*(C'\fR to temporarily block signals. This is not |
|
|
4427 | allowed in a threaded program (\f(CW\*(C`pthread_sigmask\*(C'\fR has to be used). Typical |
|
|
4428 | pthread implementations will either allow \f(CW\*(C`sigprocmask\*(C'\fR in the \*(L"main |
|
|
4429 | thread\*(R" or will block signals process-wide, both behaviours would |
|
|
4430 | be compatible with libev. Interaction between \f(CW\*(C`sigprocmask\*(C'\fR and |
|
|
4431 | \&\f(CW\*(C`pthread_sigmask\*(C'\fR could complicate things, however. |
|
|
4432 | .Sp |
|
|
4433 | The most portable way to handle signals is to block signals in all threads |
|
|
4434 | except the initial one, and run the default loop in the initial thread as |
|
|
4435 | well. |
|
|
4436 | .ie n .IP """long"" must be large enough for common memory allocation sizes" 4 |
|
|
4437 | .el .IP "\f(CWlong\fR must be large enough for common memory allocation sizes" 4 |
|
|
4438 | .IX Item "long must be large enough for common memory allocation sizes" |
|
|
4439 | To improve portability and simplify its \s-1API\s0, libev uses \f(CW\*(C`long\*(C'\fR internally |
|
|
4440 | instead of \f(CW\*(C`size_t\*(C'\fR when allocating its data structures. On non-POSIX |
|
|
4441 | systems (Microsoft...) this might be unexpectedly low, but is still at |
|
|
4442 | least 31 bits everywhere, which is enough for hundreds of millions of |
|
|
4443 | watchers. |
|
|
4444 | .ie n .IP """double"" must hold a time value in seconds with enough accuracy" 4 |
|
|
4445 | .el .IP "\f(CWdouble\fR must hold a time value in seconds with enough accuracy" 4 |
|
|
4446 | .IX Item "double must hold a time value in seconds with enough accuracy" |
|
|
4447 | The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to |
|
|
4448 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
|
|
4449 | enough for at least into the year 4000. This requirement is fulfilled by |
|
|
4450 | implementations implementing \s-1IEEE\s0 754, which is basically all existing |
|
|
4451 | ones. With \s-1IEEE\s0 754 doubles, you get microsecond accuracy until at least |
|
|
4452 | 2200. |
|
|
4453 | .PP |
|
|
4454 | If you know of other additional requirements drop me a note. |
2338 | .SH "COMPLEXITIES" |
4455 | .SH "ALGORITHMIC COMPLEXITIES" |
2339 | .IX Header "COMPLEXITIES" |
4456 | .IX Header "ALGORITHMIC COMPLEXITIES" |
2340 | In this section the complexities of (many of) the algorithms used inside |
4457 | In this section the complexities of (many of) the algorithms used inside |
2341 | libev will be explained. For complexity discussions about backends see the |
4458 | libev will be documented. For complexity discussions about backends see |
2342 | documentation for \f(CW\*(C`ev_default_init\*(C'\fR. |
4459 | the documentation for \f(CW\*(C`ev_default_init\*(C'\fR. |
2343 | .RS 4 |
4460 | .PP |
|
|
4461 | All of the following are about amortised time: If an array needs to be |
|
|
4462 | extended, libev needs to realloc and move the whole array, but this |
|
|
4463 | happens asymptotically rarer with higher number of elements, so O(1) might |
|
|
4464 | mean that libev does a lengthy realloc operation in rare cases, but on |
|
|
4465 | average it is much faster and asymptotically approaches constant time. |
2344 | .IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4 |
4466 | .IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4 |
2345 | .IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" |
4467 | .IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" |
|
|
4468 | This means that, when you have a watcher that triggers in one hour and |
|
|
4469 | there are 100 watchers that would trigger before that, then inserting will |
|
|
4470 | have to skip roughly seven (\f(CW\*(C`ld 100\*(C'\fR) of these watchers. |
|
|
4471 | .IP "Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers)" 4 |
|
|
4472 | .IX Item "Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers)" |
|
|
4473 | That means that changing a timer costs less than removing/adding them, |
|
|
4474 | as only the relative motion in the event queue has to be paid for. |
|
|
4475 | .IP "Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1)" 4 |
|
|
4476 | .IX Item "Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1)" |
|
|
4477 | These just add the watcher into an array or at the head of a list. |
|
|
4478 | .IP "Stopping check/prepare/idle/fork/async watchers: O(1)" 4 |
|
|
4479 | .IX Item "Stopping check/prepare/idle/fork/async watchers: O(1)" |
2346 | .PD 0 |
4480 | .PD 0 |
2347 | .IP "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 4 |
|
|
2348 | .IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" |
|
|
2349 | .IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4 |
|
|
2350 | .IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)" |
|
|
2351 | .IP "Stopping check/prepare/idle watchers: O(1)" 4 |
|
|
2352 | .IX Item "Stopping check/prepare/idle watchers: O(1)" |
|
|
2353 | .IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4 |
4481 | .IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4 |
2354 | .IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))" |
4482 | .IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))" |
|
|
4483 | .PD |
|
|
4484 | These watchers are stored in lists, so they need to be walked to find the |
|
|
4485 | correct watcher to remove. The lists are usually short (you don't usually |
|
|
4486 | have many watchers waiting for the same fd or signal: one is typical, two |
|
|
4487 | is rare). |
2355 | .IP "Finding the next timer per loop iteration: O(1)" 4 |
4488 | .IP "Finding the next timer in each loop iteration: O(1)" 4 |
2356 | .IX Item "Finding the next timer per loop iteration: O(1)" |
4489 | .IX Item "Finding the next timer in each loop iteration: O(1)" |
|
|
4490 | By virtue of using a binary or 4\-heap, the next timer is always found at a |
|
|
4491 | fixed position in the storage array. |
2357 | .IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4 |
4492 | .IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4 |
2358 | .IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" |
4493 | .IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" |
2359 | .IP "Activating one watcher: O(1)" 4 |
4494 | A change means an I/O watcher gets started or stopped, which requires |
2360 | .IX Item "Activating one watcher: O(1)" |
4495 | libev to recalculate its status (and possibly tell the kernel, depending |
2361 | .RE |
4496 | on backend and whether \f(CW\*(C`ev_io_set\*(C'\fR was used). |
2362 | .RS 4 |
4497 | .IP "Activating one watcher (putting it into the pending state): O(1)" 4 |
|
|
4498 | .IX Item "Activating one watcher (putting it into the pending state): O(1)" |
|
|
4499 | .PD 0 |
|
|
4500 | .IP "Priority handling: O(number_of_priorities)" 4 |
|
|
4501 | .IX Item "Priority handling: O(number_of_priorities)" |
2363 | .PD |
4502 | .PD |
|
|
4503 | Priorities are implemented by allocating some space for each |
|
|
4504 | priority. When doing priority-based operations, libev usually has to |
|
|
4505 | linearly search all the priorities, but starting/stopping and activating |
|
|
4506 | watchers becomes O(1) with respect to priority handling. |
|
|
4507 | .IP "Sending an ev_async: O(1)" 4 |
|
|
4508 | .IX Item "Sending an ev_async: O(1)" |
|
|
4509 | .PD 0 |
|
|
4510 | .IP "Processing ev_async_send: O(number_of_async_watchers)" 4 |
|
|
4511 | .IX Item "Processing ev_async_send: O(number_of_async_watchers)" |
|
|
4512 | .IP "Processing signals: O(max_signal_number)" 4 |
|
|
4513 | .IX Item "Processing signals: O(max_signal_number)" |
|
|
4514 | .PD |
|
|
4515 | Sending involves a system call \fIiff\fR there were no other \f(CW\*(C`ev_async_send\*(C'\fR |
|
|
4516 | calls in the current loop iteration. Checking for async and signal events |
|
|
4517 | involves iterating over all running async watchers or all signal numbers. |
|
|
4518 | .SH "GLOSSARY" |
|
|
4519 | .IX Header "GLOSSARY" |
|
|
4520 | .IP "active" 4 |
|
|
4521 | .IX Item "active" |
|
|
4522 | A watcher is active as long as it has been started (has been attached to |
|
|
4523 | an event loop) but not yet stopped (disassociated from the event loop). |
|
|
4524 | .IP "application" 4 |
|
|
4525 | .IX Item "application" |
|
|
4526 | In this document, an application is whatever is using libev. |
|
|
4527 | .IP "callback" 4 |
|
|
4528 | .IX Item "callback" |
|
|
4529 | The address of a function that is called when some event has been |
|
|
4530 | detected. Callbacks are being passed the event loop, the watcher that |
|
|
4531 | received the event, and the actual event bitset. |
|
|
4532 | .IP "callback invocation" 4 |
|
|
4533 | .IX Item "callback invocation" |
|
|
4534 | The act of calling the callback associated with a watcher. |
|
|
4535 | .IP "event" 4 |
|
|
4536 | .IX Item "event" |
|
|
4537 | A change of state of some external event, such as data now being available |
|
|
4538 | for reading on a file descriptor, time having passed or simply not having |
|
|
4539 | any other events happening anymore. |
|
|
4540 | .Sp |
|
|
4541 | In libev, events are represented as single bits (such as \f(CW\*(C`EV_READ\*(C'\fR or |
|
|
4542 | \&\f(CW\*(C`EV_TIMEOUT\*(C'\fR). |
|
|
4543 | .IP "event library" 4 |
|
|
4544 | .IX Item "event library" |
|
|
4545 | A software package implementing an event model and loop. |
|
|
4546 | .IP "event loop" 4 |
|
|
4547 | .IX Item "event loop" |
|
|
4548 | An entity that handles and processes external events and converts them |
|
|
4549 | into callback invocations. |
|
|
4550 | .IP "event model" 4 |
|
|
4551 | .IX Item "event model" |
|
|
4552 | The model used to describe how an event loop handles and processes |
|
|
4553 | watchers and events. |
|
|
4554 | .IP "pending" 4 |
|
|
4555 | .IX Item "pending" |
|
|
4556 | A watcher is pending as soon as the corresponding event has been detected, |
|
|
4557 | and stops being pending as soon as the watcher will be invoked or its |
|
|
4558 | pending status is explicitly cleared by the application. |
|
|
4559 | .Sp |
|
|
4560 | A watcher can be pending, but not active. Stopping a watcher also clears |
|
|
4561 | its pending status. |
|
|
4562 | .IP "real time" 4 |
|
|
4563 | .IX Item "real time" |
|
|
4564 | The physical time that is observed. It is apparently strictly monotonic :) |
|
|
4565 | .IP "wall-clock time" 4 |
|
|
4566 | .IX Item "wall-clock time" |
|
|
4567 | The time and date as shown on clocks. Unlike real time, it can actually |
|
|
4568 | be wrong and jump forwards and backwards, e.g. when the you adjust your |
|
|
4569 | clock. |
|
|
4570 | .IP "watcher" 4 |
|
|
4571 | .IX Item "watcher" |
|
|
4572 | A data structure that describes interest in certain events. Watchers need |
|
|
4573 | to be started (attached to an event loop) before they can receive events. |
|
|
4574 | .IP "watcher invocation" 4 |
|
|
4575 | .IX Item "watcher invocation" |
|
|
4576 | The act of calling the callback associated with a watcher. |
2364 | .SH "AUTHOR" |
4577 | .SH "AUTHOR" |
2365 | .IX Header "AUTHOR" |
4578 | .IX Header "AUTHOR" |
2366 | Marc Lehmann <libev@schmorp.de>. |
4579 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |