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131 | .IX Title ""<STANDARD INPUT>" 1" |
134 | .IX Title "LIBEV 3" |
132 | .TH "<STANDARD INPUT>" 1 "2007-11-27" "perl v5.8.8" "User Contributed Perl Documentation" |
135 | .TH LIBEV 3 "2008-05-22" "libev-3.41" "libev - high perfromance full featured event loop" |
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137 | .\" way too many mistakes in technical documents. |
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138 | .if n .ad l |
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139 | .nh |
133 | .SH "NAME" |
140 | .SH "NAME" |
134 | libev \- a high performance full\-featured event loop written in C |
141 | libev \- a high performance full\-featured event loop written in C |
135 | .SH "SYNOPSIS" |
142 | .SH "SYNOPSIS" |
136 | .IX Header "SYNOPSIS" |
143 | .IX Header "SYNOPSIS" |
137 | .Vb 1 |
144 | .Vb 1 |
138 | \& #include <ev.h> |
145 | \& #include <ev.h> |
139 | .Ve |
146 | .Ve |
140 | .SH "EXAMPLE PROGRAM" |
147 | .Sh "\s-1EXAMPLE\s0 \s-1PROGRAM\s0" |
141 | .IX Header "EXAMPLE PROGRAM" |
148 | .IX Subsection "EXAMPLE PROGRAM" |
142 | .Vb 1 |
149 | .Vb 2 |
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150 | \& // a single header file is required |
143 | \& #include <ev.h> |
151 | \& #include <ev.h> |
144 | .Ve |
152 | \& |
145 | .PP |
153 | \& // every watcher type has its own typedef\*(Aqd struct |
146 | .Vb 2 |
154 | \& // with the name ev_<type> |
147 | \& ev_io stdin_watcher; |
155 | \& ev_io stdin_watcher; |
148 | \& ev_timer timeout_watcher; |
156 | \& ev_timer timeout_watcher; |
149 | .Ve |
157 | \& |
150 | .PP |
158 | \& // all watcher callbacks have a similar signature |
151 | .Vb 8 |
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152 | \& /* called when data readable on stdin */ |
159 | \& // this callback is called when data is readable on stdin |
153 | \& static void |
160 | \& static void |
154 | \& stdin_cb (EV_P_ struct ev_io *w, int revents) |
161 | \& stdin_cb (EV_P_ struct ev_io *w, int revents) |
155 | \& { |
162 | \& { |
156 | \& /* puts ("stdin ready"); */ |
163 | \& puts ("stdin ready"); |
157 | \& ev_io_stop (EV_A_ w); /* just a syntax example */ |
164 | \& // for one\-shot events, one must manually stop the watcher |
158 | \& ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */ |
165 | \& // with its corresponding stop function. |
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166 | \& ev_io_stop (EV_A_ w); |
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167 | \& |
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168 | \& // this causes all nested ev_loop\*(Aqs to stop iterating |
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169 | \& ev_unloop (EV_A_ EVUNLOOP_ALL); |
159 | \& } |
170 | \& } |
160 | .Ve |
171 | \& |
161 | .PP |
172 | \& // another callback, this time for a time\-out |
162 | .Vb 6 |
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163 | \& static void |
173 | \& static void |
164 | \& timeout_cb (EV_P_ struct ev_timer *w, int revents) |
174 | \& timeout_cb (EV_P_ struct ev_timer *w, int revents) |
165 | \& { |
175 | \& { |
166 | \& /* puts ("timeout"); */ |
176 | \& puts ("timeout"); |
167 | \& ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */ |
177 | \& // this causes the innermost ev_loop to stop iterating |
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178 | \& ev_unloop (EV_A_ EVUNLOOP_ONE); |
168 | \& } |
179 | \& } |
169 | .Ve |
180 | \& |
170 | .PP |
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171 | .Vb 4 |
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172 | \& int |
181 | \& int |
173 | \& main (void) |
182 | \& main (void) |
174 | \& { |
183 | \& { |
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184 | \& // use the default event loop unless you have special needs |
175 | \& struct ev_loop *loop = ev_default_loop (0); |
185 | \& struct ev_loop *loop = ev_default_loop (0); |
176 | .Ve |
186 | \& |
177 | .PP |
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178 | .Vb 3 |
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179 | \& /* initialise an io watcher, then start it */ |
187 | \& // initialise an io watcher, then start it |
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188 | \& // this one will watch for stdin to become readable |
180 | \& ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
189 | \& ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
181 | \& ev_io_start (loop, &stdin_watcher); |
190 | \& ev_io_start (loop, &stdin_watcher); |
182 | .Ve |
191 | \& |
183 | .PP |
192 | \& // initialise a timer watcher, then start it |
184 | .Vb 3 |
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185 | \& /* simple non-repeating 5.5 second timeout */ |
193 | \& // simple non\-repeating 5.5 second timeout |
186 | \& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
194 | \& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
187 | \& ev_timer_start (loop, &timeout_watcher); |
195 | \& ev_timer_start (loop, &timeout_watcher); |
188 | .Ve |
196 | \& |
189 | .PP |
197 | \& // 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); |
198 | \& ev_loop (loop, 0); |
193 | .Ve |
199 | \& |
194 | .PP |
200 | \& // unloop was called, so exit |
195 | .Vb 2 |
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196 | \& return 0; |
201 | \& return 0; |
197 | \& } |
202 | \& } |
198 | .Ve |
203 | .Ve |
199 | .SH "DESCRIPTION" |
204 | .SH "DESCRIPTION" |
200 | .IX Header "DESCRIPTION" |
205 | .IX Header "DESCRIPTION" |
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206 | The newest version of this document is also available as an html-formatted |
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207 | web page you might find easier to navigate when reading it for the first |
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208 | time: <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>. |
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209 | .PP |
201 | Libev is an event loop: you register interest in certain events (such as a |
210 | 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 |
211 | file descriptor being readable or a timeout occurring), and it will manage |
203 | these event sources and provide your program with events. |
212 | these event sources and provide your program with events. |
204 | .PP |
213 | .PP |
205 | To do this, it must take more or less complete control over your process |
214 | 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 |
215 | (or thread) by executing the \fIevent loop\fR handler, and will then |
207 | communicate events via a callback mechanism. |
216 | communicate events via a callback mechanism. |
208 | .PP |
217 | .PP |
209 | You register interest in certain events by registering so-called \fIevent |
218 | You register interest in certain events by registering so-called \fIevent |
210 | watchers\fR, which are relatively small C structures you initialise with the |
219 | 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 |
220 | details of the event, and then hand it over to libev by \fIstarting\fR the |
212 | watcher. |
221 | watcher. |
213 | .SH "FEATURES" |
222 | .Sh "\s-1FEATURES\s0" |
214 | .IX Header "FEATURES" |
223 | .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 |
224 | 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 |
225 | 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), relative timers (\f(CW\*(C`ev_timer\*(C'\fR), |
226 | for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR interface |
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227 | (for \f(CW\*(C`ev_stat\*(C'\fR), relative timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers |
218 | absolute timers with customised rescheduling (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous |
228 | with customised rescheduling (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals |
219 | signals (\f(CW\*(C`ev_signal\*(C'\fR), process status change events (\f(CW\*(C`ev_child\*(C'\fR), and |
229 | (\f(CW\*(C`ev_signal\*(C'\fR), process status change events (\f(CW\*(C`ev_child\*(C'\fR), and event |
220 | event watchers dealing with the event loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR, |
230 | watchers dealing with the event loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR, |
221 | \&\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 |
231 | \&\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 |
222 | file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even limited support for fork events |
232 | file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even limited support for fork events |
223 | (\f(CW\*(C`ev_fork\*(C'\fR). |
233 | (\f(CW\*(C`ev_fork\*(C'\fR). |
224 | .PP |
234 | .PP |
225 | It also is quite fast (see this |
235 | It also is quite fast (see this |
226 | benchmark comparing it to libevent |
236 | benchmark comparing it to libevent |
227 | for example). |
237 | for example). |
228 | .SH "CONVENTIONS" |
238 | .Sh "\s-1CONVENTIONS\s0" |
229 | .IX Header "CONVENTIONS" |
239 | .IX Subsection "CONVENTIONS" |
230 | Libev is very configurable. In this manual the default configuration will |
240 | Libev is very configurable. In this manual the default (and most common) |
231 | be described, which supports multiple event loops. For more info about |
241 | configuration will be described, which supports multiple event loops. For |
232 | various configuration options please have a look at \fB\s-1EMBED\s0\fR section in |
242 | more info about various configuration options please have a look at |
233 | this manual. If libev was configured without support for multiple event |
243 | \&\fB\s-1EMBED\s0\fR section in this manual. If libev was configured without support |
234 | loops, then all functions taking an initial argument of name \f(CW\*(C`loop\*(C'\fR |
244 | for multiple event loops, then all functions taking an initial argument of |
235 | (which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) will not have this argument. |
245 | name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) will not have |
236 | .SH "TIME REPRESENTATION" |
246 | this argument. |
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247 | .Sh "\s-1TIME\s0 \s-1REPRESENTATION\s0" |
237 | .IX Header "TIME REPRESENTATION" |
248 | .IX Subsection "TIME REPRESENTATION" |
238 | Libev represents time as a single floating point number, representing the |
249 | Libev represents time as a single floating point number, representing the |
239 | (fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere near |
250 | (fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere near |
240 | the beginning of 1970, details are complicated, don't ask). This type is |
251 | the beginning of 1970, details are complicated, don't ask). This type is |
241 | called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually aliases |
252 | called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually aliases |
242 | to the \f(CW\*(C`double\*(C'\fR type in C, and when you need to do any calculations on |
253 | to the \f(CW\*(C`double\*(C'\fR type in C, and when you need to do any calculations on |
243 | it, you should treat it as such. |
254 | it, you should treat it as some floatingpoint value. Unlike the name |
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255 | component \f(CW\*(C`stamp\*(C'\fR might indicate, it is also used for time differences |
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256 | throughout libev. |
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257 | .SH "ERROR HANDLING" |
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258 | .IX Header "ERROR HANDLING" |
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259 | Libev knows three classes of errors: operating system errors, usage errors |
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260 | and internal errors (bugs). |
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261 | .PP |
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262 | When libev catches an operating system error it cannot handle (for example |
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263 | a syscall indicating a condition libev cannot fix), it calls the callback |
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264 | set via \f(CW\*(C`ev_set_syserr_cb\*(C'\fR, which is supposed to fix the problem or |
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265 | abort. The default is to print a diagnostic message and to call \f(CW\*(C`abort |
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266 | ()\*(C'\fR. |
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267 | .PP |
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268 | When libev detects a usage error such as a negative timer interval, then |
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269 | it will print a diagnostic message and abort (via the \f(CW\*(C`assert\*(C'\fR mechanism, |
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270 | so \f(CW\*(C`NDEBUG\*(C'\fR will disable this checking): these are programming errors in |
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271 | the libev caller and need to be fixed there. |
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272 | .PP |
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273 | Libev also has a few internal error-checking \f(CW\*(C`assert\*(C'\fRions, and also has |
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274 | extensive consistency checking code. These do not trigger under normal |
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275 | circumstances, as they indicate either a bug in libev or worse. |
244 | .SH "GLOBAL FUNCTIONS" |
276 | .SH "GLOBAL FUNCTIONS" |
245 | .IX Header "GLOBAL FUNCTIONS" |
277 | .IX Header "GLOBAL FUNCTIONS" |
246 | These functions can be called anytime, even before initialising the |
278 | These functions can be called anytime, even before initialising the |
247 | library in any way. |
279 | library in any way. |
248 | .IP "ev_tstamp ev_time ()" 4 |
280 | .IP "ev_tstamp ev_time ()" 4 |
249 | .IX Item "ev_tstamp ev_time ()" |
281 | .IX Item "ev_tstamp ev_time ()" |
250 | Returns the current time as libev would use it. Please note that the |
282 | Returns the current time as libev would use it. Please note that the |
251 | \&\f(CW\*(C`ev_now\*(C'\fR function is usually faster and also often returns the timestamp |
283 | \&\f(CW\*(C`ev_now\*(C'\fR function is usually faster and also often returns the timestamp |
252 | you actually want to know. |
284 | you actually want to know. |
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285 | .IP "ev_sleep (ev_tstamp interval)" 4 |
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286 | .IX Item "ev_sleep (ev_tstamp interval)" |
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287 | Sleep for the given interval: The current thread will be blocked until |
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288 | either it is interrupted or the given time interval has passed. Basically |
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289 | this is a subsecond-resolution \f(CW\*(C`sleep ()\*(C'\fR. |
253 | .IP "int ev_version_major ()" 4 |
290 | .IP "int ev_version_major ()" 4 |
254 | .IX Item "int ev_version_major ()" |
291 | .IX Item "int ev_version_major ()" |
255 | .PD 0 |
292 | .PD 0 |
256 | .IP "int ev_version_minor ()" 4 |
293 | .IP "int ev_version_minor ()" 4 |
257 | .IX Item "int ev_version_minor ()" |
294 | .IX Item "int ev_version_minor ()" |
258 | .PD |
295 | .PD |
259 | You can find out the major and minor version numbers of the library |
296 | You can find out the major and minor \s-1ABI\s0 version numbers of the library |
260 | you linked against by calling the functions \f(CW\*(C`ev_version_major\*(C'\fR and |
297 | you linked against by calling the functions \f(CW\*(C`ev_version_major\*(C'\fR and |
261 | \&\f(CW\*(C`ev_version_minor\*(C'\fR. If you want, you can compare against the global |
298 | \&\f(CW\*(C`ev_version_minor\*(C'\fR. If you want, you can compare against the global |
262 | symbols \f(CW\*(C`EV_VERSION_MAJOR\*(C'\fR and \f(CW\*(C`EV_VERSION_MINOR\*(C'\fR, which specify the |
299 | symbols \f(CW\*(C`EV_VERSION_MAJOR\*(C'\fR and \f(CW\*(C`EV_VERSION_MINOR\*(C'\fR, which specify the |
263 | version of the library your program was compiled against. |
300 | version of the library your program was compiled against. |
264 | .Sp |
301 | .Sp |
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302 | These version numbers refer to the \s-1ABI\s0 version of the library, not the |
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303 | release version. |
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304 | .Sp |
265 | Usually, it's a good idea to terminate if the major versions mismatch, |
305 | Usually, it's a good idea to terminate if the major versions mismatch, |
266 | as this indicates an incompatible change. Minor versions are usually |
306 | as this indicates an incompatible change. Minor versions are usually |
267 | compatible to older versions, so a larger minor version alone is usually |
307 | compatible to older versions, so a larger minor version alone is usually |
268 | not a problem. |
308 | not a problem. |
269 | .Sp |
309 | .Sp |
270 | Example: Make sure we haven't accidentally been linked against the wrong |
310 | Example: Make sure we haven't accidentally been linked against the wrong |
271 | version. |
311 | version. |
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298 | (assuming you know what you are doing). This is the set of backends that |
338 | (assuming you know what you are doing). This is the set of backends that |
299 | libev will probe for if you specify no backends explicitly. |
339 | libev will probe for if you specify no backends explicitly. |
300 | .IP "unsigned int ev_embeddable_backends ()" 4 |
340 | .IP "unsigned int ev_embeddable_backends ()" 4 |
301 | .IX Item "unsigned int ev_embeddable_backends ()" |
341 | .IX Item "unsigned int ev_embeddable_backends ()" |
302 | Returns the set of backends that are embeddable in other event loops. This |
342 | Returns the set of backends that are embeddable in other event loops. This |
303 | is the theoretical, all\-platform, value. To find which backends |
343 | is the theoretical, all-platform, value. To find which backends |
304 | might be supported on the current system, you would need to look at |
344 | might be supported on the current system, you would need to look at |
305 | \&\f(CW\*(C`ev_embeddable_backends () & ev_supported_backends ()\*(C'\fR, likewise for |
345 | \&\f(CW\*(C`ev_embeddable_backends () & ev_supported_backends ()\*(C'\fR, likewise for |
306 | recommended ones. |
346 | recommended ones. |
307 | .Sp |
347 | .Sp |
308 | See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
348 | See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
309 | .IP "ev_set_allocator (void *(*cb)(void *ptr, size_t size))" 4 |
349 | .IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4 |
310 | .IX Item "ev_set_allocator (void *(*cb)(void *ptr, size_t size))" |
350 | .IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))" |
311 | Sets the allocation function to use (the prototype and semantics are |
351 | Sets the allocation function to use (the prototype is similar \- the |
312 | identical to the realloc C function). It is used to allocate and free |
352 | semantics are identical to the \f(CW\*(C`realloc\*(C'\fR C89/SuS/POSIX function). It is |
313 | memory (no surprises here). If it returns zero when memory needs to be |
353 | used to allocate and free memory (no surprises here). If it returns zero |
314 | allocated, the library might abort or take some potentially destructive |
354 | when memory needs to be allocated (\f(CW\*(C`size != 0\*(C'\fR), the library might abort |
315 | action. The default is your system realloc function. |
355 | or take some potentially destructive action. |
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356 | .Sp |
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357 | Since some systems (at least OpenBSD and Darwin) fail to implement |
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358 | correct \f(CW\*(C`realloc\*(C'\fR semantics, libev will use a wrapper around the system |
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359 | \&\f(CW\*(C`realloc\*(C'\fR and \f(CW\*(C`free\*(C'\fR functions by default. |
316 | .Sp |
360 | .Sp |
317 | You could override this function in high-availability programs to, say, |
361 | You could override this function in high-availability programs to, say, |
318 | free some memory if it cannot allocate memory, to use a special allocator, |
362 | free some memory if it cannot allocate memory, to use a special allocator, |
319 | or even to sleep a while and retry until some memory is available. |
363 | or even to sleep a while and retry until some memory is available. |
320 | .Sp |
364 | .Sp |
321 | Example: Replace the libev allocator with one that waits a bit and then |
365 | Example: Replace the libev allocator with one that waits a bit and then |
322 | retries). |
366 | retries (example requires a standards-compliant \f(CW\*(C`realloc\*(C'\fR). |
323 | .Sp |
367 | .Sp |
324 | .Vb 6 |
368 | .Vb 6 |
325 | \& static void * |
369 | \& static void * |
326 | \& persistent_realloc (void *ptr, size_t size) |
370 | \& persistent_realloc (void *ptr, size_t size) |
327 | \& { |
371 | \& { |
328 | \& for (;;) |
372 | \& for (;;) |
329 | \& { |
373 | \& { |
330 | \& void *newptr = realloc (ptr, size); |
374 | \& void *newptr = realloc (ptr, size); |
331 | .Ve |
375 | \& |
332 | .Sp |
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333 | .Vb 2 |
|
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334 | \& if (newptr) |
376 | \& if (newptr) |
335 | \& return newptr; |
377 | \& return newptr; |
336 | .Ve |
378 | \& |
337 | .Sp |
|
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338 | .Vb 3 |
|
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339 | \& sleep (60); |
379 | \& sleep (60); |
340 | \& } |
380 | \& } |
341 | \& } |
381 | \& } |
342 | .Ve |
382 | \& |
343 | .Sp |
|
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344 | .Vb 2 |
|
|
345 | \& ... |
383 | \& ... |
346 | \& ev_set_allocator (persistent_realloc); |
384 | \& ev_set_allocator (persistent_realloc); |
347 | .Ve |
385 | .Ve |
348 | .IP "ev_set_syserr_cb (void (*cb)(const char *msg));" 4 |
386 | .IP "ev_set_syserr_cb (void (*cb)(const char *msg));" 4 |
349 | .IX Item "ev_set_syserr_cb (void (*cb)(const char *msg));" |
387 | .IX Item "ev_set_syserr_cb (void (*cb)(const char *msg));" |
… | |
… | |
362 | \& fatal_error (const char *msg) |
400 | \& fatal_error (const char *msg) |
363 | \& { |
401 | \& { |
364 | \& perror (msg); |
402 | \& perror (msg); |
365 | \& abort (); |
403 | \& abort (); |
366 | \& } |
404 | \& } |
367 | .Ve |
405 | \& |
368 | .Sp |
|
|
369 | .Vb 2 |
|
|
370 | \& ... |
406 | \& ... |
371 | \& ev_set_syserr_cb (fatal_error); |
407 | \& ev_set_syserr_cb (fatal_error); |
372 | .Ve |
408 | .Ve |
373 | .SH "FUNCTIONS CONTROLLING THE EVENT LOOP" |
409 | .SH "FUNCTIONS CONTROLLING THE EVENT LOOP" |
374 | .IX Header "FUNCTIONS CONTROLLING THE EVENT LOOP" |
410 | .IX Header "FUNCTIONS CONTROLLING THE EVENT LOOP" |
375 | An event loop is described by a \f(CW\*(C`struct ev_loop *\*(C'\fR. The library knows two |
411 | An event loop is described by a \f(CW\*(C`struct ev_loop *\*(C'\fR. The library knows two |
376 | types of such loops, the \fIdefault\fR loop, which supports signals and child |
412 | types of such loops, the \fIdefault\fR loop, which supports signals and child |
377 | events, and dynamically created loops which do not. |
413 | events, and dynamically created loops which do not. |
378 | .PP |
|
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379 | If you use threads, a common model is to run the default event loop |
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380 | in your main thread (or in a separate thread) and for each thread you |
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381 | create, you also create another event loop. Libev itself does no locking |
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382 | whatsoever, so if you mix calls to the same event loop in different |
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383 | threads, make sure you lock (this is usually a bad idea, though, even if |
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384 | done correctly, because it's hideous and inefficient). |
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385 | .IP "struct ev_loop *ev_default_loop (unsigned int flags)" 4 |
414 | .IP "struct ev_loop *ev_default_loop (unsigned int flags)" 4 |
386 | .IX Item "struct ev_loop *ev_default_loop (unsigned int flags)" |
415 | .IX Item "struct ev_loop *ev_default_loop (unsigned int flags)" |
387 | This will initialise the default event loop if it hasn't been initialised |
416 | This will initialise the default event loop if it hasn't been initialised |
388 | yet and return it. If the default loop could not be initialised, returns |
417 | yet and return it. If the default loop could not be initialised, returns |
389 | false. If it already was initialised it simply returns it (and ignores the |
418 | false. If it already was initialised it simply returns it (and ignores the |
390 | flags. If that is troubling you, check \f(CW\*(C`ev_backend ()\*(C'\fR afterwards). |
419 | flags. If that is troubling you, check \f(CW\*(C`ev_backend ()\*(C'\fR afterwards). |
391 | .Sp |
420 | .Sp |
392 | If you don't know what event loop to use, use the one returned from this |
421 | If you don't know what event loop to use, use the one returned from this |
393 | function. |
422 | function. |
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423 | .Sp |
|
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424 | Note that this function is \fInot\fR thread-safe, so if you want to use it |
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425 | from multiple threads, you have to lock (note also that this is unlikely, |
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426 | as loops cannot bes hared easily between threads anyway). |
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427 | .Sp |
|
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428 | The default loop is the only loop that can handle \f(CW\*(C`ev_signal\*(C'\fR and |
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429 | \&\f(CW\*(C`ev_child\*(C'\fR watchers, and to do this, it always registers a handler |
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430 | for \f(CW\*(C`SIGCHLD\*(C'\fR. If this is a problem for your app you can either |
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431 | create a dynamic loop with \f(CW\*(C`ev_loop_new\*(C'\fR that doesn't do that, or you |
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432 | can simply overwrite the \f(CW\*(C`SIGCHLD\*(C'\fR signal handler \fIafter\fR calling |
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433 | \&\f(CW\*(C`ev_default_init\*(C'\fR. |
394 | .Sp |
434 | .Sp |
395 | The flags argument can be used to specify special behaviour or specific |
435 | The flags argument can be used to specify special behaviour or specific |
396 | backends to use, and is usually specified as \f(CW0\fR (or \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). |
436 | backends to use, and is usually specified as \f(CW0\fR (or \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). |
397 | .Sp |
437 | .Sp |
398 | The following flags are supported: |
438 | The following flags are supported: |
… | |
… | |
409 | or setgid) then libev will \fInot\fR look at the environment variable |
449 | or setgid) then libev will \fInot\fR look at the environment variable |
410 | \&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will |
450 | \&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will |
411 | override the flags completely if it is found in the environment. This is |
451 | override the flags completely if it is found in the environment. This is |
412 | useful to try out specific backends to test their performance, or to work |
452 | useful to try out specific backends to test their performance, or to work |
413 | around bugs. |
453 | around bugs. |
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454 | .ie n .IP """EVFLAG_FORKCHECK""" 4 |
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455 | .el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4 |
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456 | .IX Item "EVFLAG_FORKCHECK" |
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457 | Instead of calling \f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR manually after |
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458 | a fork, you can also make libev check for a fork in each iteration by |
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459 | enabling this flag. |
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460 | .Sp |
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461 | This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop, |
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462 | and thus this might slow down your event loop if you do a lot of loop |
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463 | iterations and little real work, but is usually not noticeable (on my |
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464 | GNU/Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence |
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465 | without a syscall and thus \fIvery\fR fast, but my GNU/Linux system also has |
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466 | \&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster). |
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467 | .Sp |
|
|
468 | The big advantage of this flag is that you can forget about fork (and |
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469 | forget about forgetting to tell libev about forking) when you use this |
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470 | flag. |
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471 | .Sp |
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472 | This flag setting cannot be overriden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR |
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|
473 | environment variable. |
414 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
474 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
415 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
475 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
416 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
476 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
417 | This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
477 | This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
418 | libev tries to roll its own fd_set with no limits on the number of fds, |
478 | libev tries to roll its own fd_set with no limits on the number of fds, |
419 | but if that fails, expect a fairly low limit on the number of fds when |
479 | but if that fails, expect a fairly low limit on the number of fds when |
420 | using this backend. It doesn't scale too well (O(highest_fd)), but its usually |
480 | using this backend. It doesn't scale too well (O(highest_fd)), but its |
421 | the fastest backend for a low number of fds. |
481 | usually the fastest backend for a low number of (low-numbered :) fds. |
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482 | .Sp |
|
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483 | To get good performance out of this backend you need a high amount of |
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484 | parallelity (most of the file descriptors should be busy). If you are |
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485 | writing a server, you should \f(CW\*(C`accept ()\*(C'\fR in a loop to accept as many |
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486 | connections as possible during one iteration. You might also want to have |
|
|
487 | a look at \f(CW\*(C`ev_set_io_collect_interval ()\*(C'\fR to increase the amount of |
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|
488 | readiness notifications you get per iteration. |
422 | .ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4 |
489 | .ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4 |
423 | .el .IP "\f(CWEVBACKEND_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4 |
490 | .el .IP "\f(CWEVBACKEND_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4 |
424 | .IX Item "EVBACKEND_POLL (value 2, poll backend, available everywhere except on windows)" |
491 | .IX Item "EVBACKEND_POLL (value 2, poll backend, available everywhere except on windows)" |
425 | And this is your standard \fIpoll\fR\|(2) backend. It's more complicated than |
492 | And this is your standard \fIpoll\fR\|(2) backend. It's more complicated |
426 | select, but handles sparse fds better and has no artificial limit on the |
493 | than select, but handles sparse fds better and has no artificial |
427 | number of fds you can use (except it will slow down considerably with a |
494 | limit on the number of fds you can use (except it will slow down |
428 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds). |
495 | considerably with a lot of inactive fds). It scales similarly to select, |
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496 | i.e. O(total_fds). See the entry for \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR, above, for |
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497 | performance tips. |
429 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
498 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
430 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
499 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
431 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
500 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
432 | For few fds, this backend is a bit little slower than poll and select, |
501 | For few fds, this backend is a bit little slower than poll and select, |
433 | but it scales phenomenally better. While poll and select usually scale like |
502 | but it scales phenomenally better. While poll and select usually scale |
434 | O(total_fds) where n is the total number of fds (or the highest fd), epoll scales |
503 | like O(total_fds) where n is the total number of fds (or the highest fd), |
435 | either O(1) or O(active_fds). |
504 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
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505 | of shortcomings, such as silently dropping events in some hard-to-detect |
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506 | cases and requiring a syscall per fd change, no fork support and bad |
|
|
507 | support for dup. |
436 | .Sp |
508 | .Sp |
437 | While stopping and starting an I/O watcher in the same iteration will |
509 | While stopping, setting and starting an I/O watcher in the same iteration |
438 | result in some caching, there is still a syscall per such incident |
510 | will result in some caching, there is still a syscall per such incident |
439 | (because the fd could point to a different file description now), so its |
511 | (because the fd could point to a different file description now), so its |
440 | best to avoid that. Also, \fIdup()\fRed file descriptors might not work very |
512 | best to avoid that. Also, \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors might not work |
441 | well if you register events for both fds. |
513 | very well if you register events for both fds. |
442 | .Sp |
514 | .Sp |
443 | Please note that epoll sometimes generates spurious notifications, so you |
515 | Please note that epoll sometimes generates spurious notifications, so you |
444 | need to use non-blocking I/O or other means to avoid blocking when no data |
516 | need to use non-blocking I/O or other means to avoid blocking when no data |
445 | (or space) is available. |
517 | (or space) is available. |
|
|
518 | .Sp |
|
|
519 | Best performance from this backend is achieved by not unregistering all |
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520 | watchers for a file descriptor until it has been closed, if possible, i.e. |
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521 | keep at least one watcher active per fd at all times. |
|
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522 | .Sp |
|
|
523 | While nominally embeddeble in other event loops, this feature is broken in |
|
|
524 | all kernel versions tested so far. |
446 | .ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 |
525 | .ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 |
447 | .el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 |
526 | .el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 |
448 | .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" |
527 | .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" |
449 | Kqueue deserves special mention, as at the time of this writing, it |
528 | Kqueue deserves special mention, as at the time of this writing, it |
450 | was broken on all BSDs except NetBSD (usually it doesn't work with |
529 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
451 | anything but sockets and pipes, except on Darwin, where of course its |
530 | with anything but sockets and pipes, except on Darwin, where of course |
452 | completely useless). For this reason its not being \*(L"autodetected\*(R" |
531 | it's completely useless). For this reason it's not being \*(L"autodetected\*(R" |
453 | unless you explicitly specify it explicitly in the flags (i.e. using |
532 | unless you explicitly specify it explicitly in the flags (i.e. using |
454 | \&\f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR). |
533 | \&\f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR) or libev was compiled on a known-to-be-good (\-enough) |
|
|
534 | system like NetBSD. |
|
|
535 | .Sp |
|
|
536 | You still can embed kqueue into a normal poll or select backend and use it |
|
|
537 | only for sockets (after having made sure that sockets work with kqueue on |
|
|
538 | the target platform). See \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
455 | .Sp |
539 | .Sp |
456 | It scales in the same way as the epoll backend, but the interface to the |
540 | It scales in the same way as the epoll backend, but the interface to the |
457 | kernel is more efficient (which says nothing about its actual speed, of |
541 | kernel is more efficient (which says nothing about its actual speed, of |
458 | course). While starting and stopping an I/O watcher does not cause an |
542 | course). While stopping, setting and starting an I/O watcher does never |
459 | extra syscall as with epoll, it still adds up to four event changes per |
543 | cause an extra syscall as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to |
460 | incident, so its best to avoid that. |
544 | two event changes per incident, support for \f(CW\*(C`fork ()\*(C'\fR is very bad and it |
|
|
545 | drops fds silently in similarly hard-to-detect cases. |
|
|
546 | .Sp |
|
|
547 | This backend usually performs well under most conditions. |
|
|
548 | .Sp |
|
|
549 | While nominally embeddable in other event loops, this doesn't work |
|
|
550 | everywhere, so you might need to test for this. And since it is broken |
|
|
551 | almost everywhere, you should only use it when you have a lot of sockets |
|
|
552 | (for which it usually works), by embedding it into another event loop |
|
|
553 | (e.g. \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR) and using it only for |
|
|
554 | sockets. |
461 | .ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 |
555 | .ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 |
462 | .el .IP "\f(CWEVBACKEND_DEVPOLL\fR (value 16, Solaris 8)" 4 |
556 | .el .IP "\f(CWEVBACKEND_DEVPOLL\fR (value 16, Solaris 8)" 4 |
463 | .IX Item "EVBACKEND_DEVPOLL (value 16, Solaris 8)" |
557 | .IX Item "EVBACKEND_DEVPOLL (value 16, Solaris 8)" |
464 | This is not implemented yet (and might never be). |
558 | This is not implemented yet (and might never be, unless you send me an |
|
|
559 | implementation). According to reports, \f(CW\*(C`/dev/poll\*(C'\fR only supports sockets |
|
|
560 | and is not embeddable, which would limit the usefulness of this backend |
|
|
561 | immensely. |
465 | .ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 |
562 | .ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 |
466 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
563 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
467 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
564 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
468 | This uses the Solaris 10 port mechanism. As with everything on Solaris, |
565 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
469 | it's really slow, but it still scales very well (O(active_fds)). |
566 | it's really slow, but it still scales very well (O(active_fds)). |
470 | .Sp |
567 | .Sp |
471 | Please note that solaris ports can result in a lot of spurious |
568 | Please note that solaris event ports can deliver a lot of spurious |
472 | notifications, so you need to use non-blocking I/O or other means to avoid |
569 | notifications, so you need to use non-blocking I/O or other means to avoid |
473 | blocking when no data (or space) is available. |
570 | blocking when no data (or space) is available. |
|
|
571 | .Sp |
|
|
572 | While this backend scales well, it requires one system call per active |
|
|
573 | file descriptor per loop iteration. For small and medium numbers of file |
|
|
574 | descriptors a \*(L"slow\*(R" \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR backend |
|
|
575 | might perform better. |
|
|
576 | .Sp |
|
|
577 | On the positive side, ignoring the spurious readiness notifications, this |
|
|
578 | backend actually performed to specification in all tests and is fully |
|
|
579 | embeddable, which is a rare feat among the OS-specific backends. |
474 | .ie n .IP """EVBACKEND_ALL""" 4 |
580 | .ie n .IP """EVBACKEND_ALL""" 4 |
475 | .el .IP "\f(CWEVBACKEND_ALL\fR" 4 |
581 | .el .IP "\f(CWEVBACKEND_ALL\fR" 4 |
476 | .IX Item "EVBACKEND_ALL" |
582 | .IX Item "EVBACKEND_ALL" |
477 | Try all backends (even potentially broken ones that wouldn't be tried |
583 | Try all backends (even potentially broken ones that wouldn't be tried |
478 | with \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). Since this is a mask, you can do stuff such as |
584 | with \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). Since this is a mask, you can do stuff such as |
479 | \&\f(CW\*(C`EVBACKEND_ALL & ~EVBACKEND_KQUEUE\*(C'\fR. |
585 | \&\f(CW\*(C`EVBACKEND_ALL & ~EVBACKEND_KQUEUE\*(C'\fR. |
|
|
586 | .Sp |
|
|
587 | It is definitely not recommended to use this flag. |
480 | .RE |
588 | .RE |
481 | .RS 4 |
589 | .RS 4 |
482 | .Sp |
590 | .Sp |
483 | If one or more of these are ored into the flags value, then only these |
591 | If one or more of these are ored into the flags value, then only these |
484 | backends will be tried (in the reverse order as given here). If none are |
592 | backends will be tried (in the reverse order as listed here). If none are |
485 | specified, most compiled-in backend will be tried, usually in reverse |
593 | specified, all backends in \f(CW\*(C`ev_recommended_backends ()\*(C'\fR will be tried. |
486 | order of their flag values :) |
|
|
487 | .Sp |
594 | .Sp |
488 | The most typical usage is like this: |
595 | The most typical usage is like this: |
489 | .Sp |
596 | .Sp |
490 | .Vb 2 |
597 | .Vb 2 |
491 | \& if (!ev_default_loop (0)) |
598 | \& if (!ev_default_loop (0)) |
… | |
… | |
512 | Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is |
619 | Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is |
513 | always distinct from the default loop. Unlike the default loop, it cannot |
620 | always distinct from the default loop. Unlike the default loop, it cannot |
514 | handle signal and child watchers, and attempts to do so will be greeted by |
621 | handle signal and child watchers, and attempts to do so will be greeted by |
515 | undefined behaviour (or a failed assertion if assertions are enabled). |
622 | undefined behaviour (or a failed assertion if assertions are enabled). |
516 | .Sp |
623 | .Sp |
|
|
624 | Note that this function \fIis\fR thread-safe, and the recommended way to use |
|
|
625 | libev with threads is indeed to create one loop per thread, and using the |
|
|
626 | default loop in the \*(L"main\*(R" or \*(L"initial\*(R" thread. |
|
|
627 | .Sp |
517 | Example: Try to create a event loop that uses epoll and nothing else. |
628 | Example: Try to create a event loop that uses epoll and nothing else. |
518 | .Sp |
629 | .Sp |
519 | .Vb 3 |
630 | .Vb 3 |
520 | \& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
631 | \& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
521 | \& if (!epoller) |
632 | \& if (!epoller) |
… | |
… | |
526 | Destroys the default loop again (frees all memory and kernel state |
637 | Destroys the default loop again (frees all memory and kernel state |
527 | etc.). None of the active event watchers will be stopped in the normal |
638 | etc.). None of the active event watchers will be stopped in the normal |
528 | sense, so e.g. \f(CW\*(C`ev_is_active\*(C'\fR might still return true. It is your |
639 | sense, so e.g. \f(CW\*(C`ev_is_active\*(C'\fR might still return true. It is your |
529 | responsibility to either stop all watchers cleanly yoursef \fIbefore\fR |
640 | responsibility to either stop all watchers cleanly yoursef \fIbefore\fR |
530 | calling this function, or cope with the fact afterwards (which is usually |
641 | calling this function, or cope with the fact afterwards (which is usually |
531 | the easiest thing, youc na just ignore the watchers and/or \f(CW\*(C`free ()\*(C'\fR them |
642 | the easiest thing, you can just ignore the watchers and/or \f(CW\*(C`free ()\*(C'\fR them |
532 | for example). |
643 | for example). |
|
|
644 | .Sp |
|
|
645 | Note that certain global state, such as signal state, will not be freed by |
|
|
646 | this function, and related watchers (such as signal and child watchers) |
|
|
647 | would need to be stopped manually. |
|
|
648 | .Sp |
|
|
649 | In general it is not advisable to call this function except in the |
|
|
650 | rare occasion where you really need to free e.g. the signal handling |
|
|
651 | pipe fds. If you need dynamically allocated loops it is better to use |
|
|
652 | \&\f(CW\*(C`ev_loop_new\*(C'\fR and \f(CW\*(C`ev_loop_destroy\*(C'\fR). |
533 | .IP "ev_loop_destroy (loop)" 4 |
653 | .IP "ev_loop_destroy (loop)" 4 |
534 | .IX Item "ev_loop_destroy (loop)" |
654 | .IX Item "ev_loop_destroy (loop)" |
535 | Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an |
655 | Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an |
536 | earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR. |
656 | earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR. |
537 | .IP "ev_default_fork ()" 4 |
657 | .IP "ev_default_fork ()" 4 |
538 | .IX Item "ev_default_fork ()" |
658 | .IX Item "ev_default_fork ()" |
|
|
659 | This function sets a flag that causes subsequent \f(CW\*(C`ev_loop\*(C'\fR iterations |
539 | This function reinitialises the kernel state for backends that have |
660 | to reinitialise the kernel state for backends that have one. Despite the |
540 | one. Despite the name, you can call it anytime, but it makes most sense |
661 | name, you can call it anytime, but it makes most sense after forking, in |
541 | after forking, in either the parent or child process (or both, but that |
662 | the child process (or both child and parent, but that again makes little |
542 | again makes little sense). |
663 | sense). You \fImust\fR call it in the child before using any of the libev |
|
|
664 | functions, and it will only take effect at the next \f(CW\*(C`ev_loop\*(C'\fR iteration. |
543 | .Sp |
665 | .Sp |
544 | You \fImust\fR call this function in the child process after forking if and |
666 | On the other hand, you only need to call this function in the child |
545 | only if you want to use the event library in both processes. If you just |
667 | process if and only if you want to use the event library in the child. If |
546 | fork+exec, you don't have to call it. |
668 | you just fork+exec, you don't have to call it at all. |
547 | .Sp |
669 | .Sp |
548 | The function itself is quite fast and it's usually not a problem to call |
670 | The function itself is quite fast and it's usually not a problem to call |
549 | it just in case after a fork. To make this easy, the function will fit in |
671 | it just in case after a fork. To make this easy, the function will fit in |
550 | quite nicely into a call to \f(CW\*(C`pthread_atfork\*(C'\fR: |
672 | quite nicely into a call to \f(CW\*(C`pthread_atfork\*(C'\fR: |
551 | .Sp |
673 | .Sp |
552 | .Vb 1 |
674 | .Vb 1 |
553 | \& pthread_atfork (0, 0, ev_default_fork); |
675 | \& pthread_atfork (0, 0, ev_default_fork); |
554 | .Ve |
676 | .Ve |
555 | .Sp |
|
|
556 | At the moment, \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and \f(CW\*(C`EVBACKEND_POLL\*(C'\fR are safe to use |
|
|
557 | without calling this function, so if you force one of those backends you |
|
|
558 | do not need to care. |
|
|
559 | .IP "ev_loop_fork (loop)" 4 |
677 | .IP "ev_loop_fork (loop)" 4 |
560 | .IX Item "ev_loop_fork (loop)" |
678 | .IX Item "ev_loop_fork (loop)" |
561 | Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by |
679 | Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by |
562 | \&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop |
680 | \&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop |
563 | after fork, and how you do this is entirely your own problem. |
681 | after fork, and how you do this is entirely your own problem. |
|
|
682 | .IP "int ev_is_default_loop (loop)" 4 |
|
|
683 | .IX Item "int ev_is_default_loop (loop)" |
|
|
684 | Returns true when the given loop actually is the default loop, false otherwise. |
|
|
685 | .IP "unsigned int ev_loop_count (loop)" 4 |
|
|
686 | .IX Item "unsigned int ev_loop_count (loop)" |
|
|
687 | Returns the count of loop iterations for the loop, which is identical to |
|
|
688 | the number of times libev did poll for new events. It starts at \f(CW0\fR and |
|
|
689 | happily wraps around with enough iterations. |
|
|
690 | .Sp |
|
|
691 | This value can sometimes be useful as a generation counter of sorts (it |
|
|
692 | \&\*(L"ticks\*(R" the number of loop iterations), as it roughly corresponds with |
|
|
693 | \&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls. |
564 | .IP "unsigned int ev_backend (loop)" 4 |
694 | .IP "unsigned int ev_backend (loop)" 4 |
565 | .IX Item "unsigned int ev_backend (loop)" |
695 | .IX Item "unsigned int ev_backend (loop)" |
566 | Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in |
696 | Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in |
567 | use. |
697 | use. |
568 | .IP "ev_tstamp ev_now (loop)" 4 |
698 | .IP "ev_tstamp ev_now (loop)" 4 |
569 | .IX Item "ev_tstamp ev_now (loop)" |
699 | .IX Item "ev_tstamp ev_now (loop)" |
570 | Returns the current \*(L"event loop time\*(R", which is the time the event loop |
700 | Returns the current \*(L"event loop time\*(R", which is the time the event loop |
571 | received events and started processing them. This timestamp does not |
701 | received events and started processing them. This timestamp does not |
572 | change as long as callbacks are being processed, and this is also the base |
702 | change as long as callbacks are being processed, and this is also the base |
573 | time used for relative timers. You can treat it as the timestamp of the |
703 | time used for relative timers. You can treat it as the timestamp of the |
574 | event occuring (or more correctly, libev finding out about it). |
704 | event occurring (or more correctly, libev finding out about it). |
575 | .IP "ev_loop (loop, int flags)" 4 |
705 | .IP "ev_loop (loop, int flags)" 4 |
576 | .IX Item "ev_loop (loop, int flags)" |
706 | .IX Item "ev_loop (loop, int flags)" |
577 | Finally, this is it, the event handler. This function usually is called |
707 | Finally, this is it, the event handler. This function usually is called |
578 | after you initialised all your watchers and you want to start handling |
708 | after you initialised all your watchers and you want to start handling |
579 | events. |
709 | events. |
… | |
… | |
599 | libev watchers. However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is |
729 | libev watchers. However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is |
600 | usually a better approach for this kind of thing. |
730 | usually a better approach for this kind of thing. |
601 | .Sp |
731 | .Sp |
602 | Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does: |
732 | Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does: |
603 | .Sp |
733 | .Sp |
604 | .Vb 18 |
734 | .Vb 10 |
605 | \& * If there are no active watchers (reference count is zero), return. |
735 | \& \- Before the first iteration, call any pending watchers. |
606 | \& - Queue prepare watchers and then call all outstanding watchers. |
736 | \& * If EVFLAG_FORKCHECK was used, check for a fork. |
|
|
737 | \& \- If a fork was detected, queue and call all fork watchers. |
|
|
738 | \& \- Queue and call all prepare watchers. |
607 | \& - If we have been forked, recreate the kernel state. |
739 | \& \- If we have been forked, recreate the kernel state. |
608 | \& - Update the kernel state with all outstanding changes. |
740 | \& \- Update the kernel state with all outstanding changes. |
609 | \& - Update the "event loop time". |
741 | \& \- Update the "event loop time". |
610 | \& - Calculate for how long to block. |
742 | \& \- Calculate for how long to sleep or block, if at all |
|
|
743 | \& (active idle watchers, EVLOOP_NONBLOCK or not having |
|
|
744 | \& any active watchers at all will result in not sleeping). |
|
|
745 | \& \- Sleep if the I/O and timer collect interval say so. |
611 | \& - Block the process, waiting for any events. |
746 | \& \- Block the process, waiting for any events. |
612 | \& - Queue all outstanding I/O (fd) events. |
747 | \& \- Queue all outstanding I/O (fd) events. |
613 | \& - Update the "event loop time" and do time jump handling. |
748 | \& \- Update the "event loop time" and do time jump handling. |
614 | \& - Queue all outstanding timers. |
749 | \& \- Queue all outstanding timers. |
615 | \& - Queue all outstanding periodics. |
750 | \& \- Queue all outstanding periodics. |
616 | \& - If no events are pending now, queue all idle watchers. |
751 | \& \- If no events are pending now, queue all idle watchers. |
617 | \& - Queue all check watchers. |
752 | \& \- Queue all check watchers. |
618 | \& - Call all queued watchers in reverse order (i.e. check watchers first). |
753 | \& \- Call all queued watchers in reverse order (i.e. check watchers first). |
619 | \& Signals and child watchers are implemented as I/O watchers, and will |
754 | \& Signals and child watchers are implemented as I/O watchers, and will |
620 | \& be handled here by queueing them when their watcher gets executed. |
755 | \& be handled here by queueing them when their watcher gets executed. |
621 | \& - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
756 | \& \- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
622 | \& were used, return, otherwise continue with step *. |
757 | \& were used, or there are no active watchers, return, otherwise |
|
|
758 | \& continue with step *. |
623 | .Ve |
759 | .Ve |
624 | .Sp |
760 | .Sp |
625 | Example: Queue some jobs and then loop until no events are outsanding |
761 | Example: Queue some jobs and then loop until no events are outstanding |
626 | anymore. |
762 | anymore. |
627 | .Sp |
763 | .Sp |
628 | .Vb 4 |
764 | .Vb 4 |
629 | \& ... queue jobs here, make sure they register event watchers as long |
765 | \& ... queue jobs here, make sure they register event watchers as long |
630 | \& ... as they still have work to do (even an idle watcher will do..) |
766 | \& ... as they still have work to do (even an idle watcher will do..) |
… | |
… | |
635 | .IX Item "ev_unloop (loop, how)" |
771 | .IX Item "ev_unloop (loop, how)" |
636 | Can be used to make a call to \f(CW\*(C`ev_loop\*(C'\fR return early (but only after it |
772 | Can be used to make a call to \f(CW\*(C`ev_loop\*(C'\fR return early (but only after it |
637 | has processed all outstanding events). The \f(CW\*(C`how\*(C'\fR argument must be either |
773 | has processed all outstanding events). The \f(CW\*(C`how\*(C'\fR argument must be either |
638 | \&\f(CW\*(C`EVUNLOOP_ONE\*(C'\fR, which will make the innermost \f(CW\*(C`ev_loop\*(C'\fR call return, or |
774 | \&\f(CW\*(C`EVUNLOOP_ONE\*(C'\fR, which will make the innermost \f(CW\*(C`ev_loop\*(C'\fR call return, or |
639 | \&\f(CW\*(C`EVUNLOOP_ALL\*(C'\fR, which will make all nested \f(CW\*(C`ev_loop\*(C'\fR calls return. |
775 | \&\f(CW\*(C`EVUNLOOP_ALL\*(C'\fR, which will make all nested \f(CW\*(C`ev_loop\*(C'\fR calls return. |
|
|
776 | .Sp |
|
|
777 | This \*(L"unloop state\*(R" will be cleared when entering \f(CW\*(C`ev_loop\*(C'\fR again. |
640 | .IP "ev_ref (loop)" 4 |
778 | .IP "ev_ref (loop)" 4 |
641 | .IX Item "ev_ref (loop)" |
779 | .IX Item "ev_ref (loop)" |
642 | .PD 0 |
780 | .PD 0 |
643 | .IP "ev_unref (loop)" 4 |
781 | .IP "ev_unref (loop)" 4 |
644 | .IX Item "ev_unref (loop)" |
782 | .IX Item "ev_unref (loop)" |
… | |
… | |
650 | returning, \fIev_unref()\fR after starting, and \fIev_ref()\fR before stopping it. For |
788 | returning, \fIev_unref()\fR after starting, and \fIev_ref()\fR before stopping it. For |
651 | example, libev itself uses this for its internal signal pipe: It is not |
789 | example, libev itself uses this for its internal signal pipe: It is not |
652 | visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from exiting if |
790 | visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from exiting if |
653 | no event watchers registered by it are active. It is also an excellent |
791 | no event watchers registered by it are active. It is also an excellent |
654 | way to do this for generic recurring timers or from within third-party |
792 | way to do this for generic recurring timers or from within third-party |
655 | libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR. |
793 | libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR |
|
|
794 | (but only if the watcher wasn't active before, or was active before, |
|
|
795 | respectively). |
656 | .Sp |
796 | .Sp |
657 | Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR |
797 | Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR |
658 | running when nothing else is active. |
798 | running when nothing else is active. |
659 | .Sp |
799 | .Sp |
660 | .Vb 4 |
800 | .Vb 4 |
… | |
… | |
668 | .Sp |
808 | .Sp |
669 | .Vb 2 |
809 | .Vb 2 |
670 | \& ev_ref (loop); |
810 | \& ev_ref (loop); |
671 | \& ev_signal_stop (loop, &exitsig); |
811 | \& ev_signal_stop (loop, &exitsig); |
672 | .Ve |
812 | .Ve |
|
|
813 | .IP "ev_set_io_collect_interval (loop, ev_tstamp interval)" 4 |
|
|
814 | .IX Item "ev_set_io_collect_interval (loop, ev_tstamp interval)" |
|
|
815 | .PD 0 |
|
|
816 | .IP "ev_set_timeout_collect_interval (loop, ev_tstamp interval)" 4 |
|
|
817 | .IX Item "ev_set_timeout_collect_interval (loop, ev_tstamp interval)" |
|
|
818 | .PD |
|
|
819 | These advanced functions influence the time that libev will spend waiting |
|
|
820 | for events. Both are by default \f(CW0\fR, meaning that libev will try to |
|
|
821 | invoke timer/periodic callbacks and I/O callbacks with minimum latency. |
|
|
822 | .Sp |
|
|
823 | Setting these to a higher value (the \f(CW\*(C`interval\*(C'\fR \fImust\fR be >= \f(CW0\fR) |
|
|
824 | allows libev to delay invocation of I/O and timer/periodic callbacks to |
|
|
825 | increase efficiency of loop iterations. |
|
|
826 | .Sp |
|
|
827 | The background is that sometimes your program runs just fast enough to |
|
|
828 | handle one (or very few) event(s) per loop iteration. While this makes |
|
|
829 | the program responsive, it also wastes a lot of \s-1CPU\s0 time to poll for new |
|
|
830 | events, especially with backends like \f(CW\*(C`select ()\*(C'\fR which have a high |
|
|
831 | overhead for the actual polling but can deliver many events at once. |
|
|
832 | .Sp |
|
|
833 | By setting a higher \fIio collect interval\fR you allow libev to spend more |
|
|
834 | time collecting I/O events, so you can handle more events per iteration, |
|
|
835 | at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and |
|
|
836 | \&\f(CW\*(C`ev_timer\*(C'\fR) will be not affected. Setting this to a non-null value will |
|
|
837 | introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations. |
|
|
838 | .Sp |
|
|
839 | Likewise, by setting a higher \fItimeout collect interval\fR you allow libev |
|
|
840 | to spend more time collecting timeouts, at the expense of increased |
|
|
841 | latency (the watcher callback will be called later). \f(CW\*(C`ev_io\*(C'\fR watchers |
|
|
842 | will not be affected. Setting this to a non-null value will not introduce |
|
|
843 | any overhead in libev. |
|
|
844 | .Sp |
|
|
845 | Many (busy) programs can usually benefit by setting the io collect |
|
|
846 | interval to a value near \f(CW0.1\fR or so, which is often enough for |
|
|
847 | interactive servers (of course not for games), likewise for timeouts. It |
|
|
848 | usually doesn't make much sense to set it to a lower value than \f(CW0.01\fR, |
|
|
849 | as this approsaches the timing granularity of most systems. |
|
|
850 | .IP "ev_loop_verify (loop)" 4 |
|
|
851 | .IX Item "ev_loop_verify (loop)" |
|
|
852 | This function only does something when \f(CW\*(C`EV_VERIFY\*(C'\fR support has been |
|
|
853 | compiled in. It tries to go through all internal structures and checks |
|
|
854 | them for validity. If anything is found to be inconsistent, it will print |
|
|
855 | an error message to standard error and call \f(CW\*(C`abort ()\*(C'\fR. |
|
|
856 | .Sp |
|
|
857 | This can be used to catch bugs inside libev itself: under normal |
|
|
858 | circumstances, this function will never abort as of course libev keeps its |
|
|
859 | data structures consistent. |
673 | .SH "ANATOMY OF A WATCHER" |
860 | .SH "ANATOMY OF A WATCHER" |
674 | .IX Header "ANATOMY OF A WATCHER" |
861 | .IX Header "ANATOMY OF A WATCHER" |
675 | A watcher is a structure that you create and register to record your |
862 | A watcher is a structure that you create and register to record your |
676 | interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to |
863 | interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to |
677 | become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher for that: |
864 | become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher for that: |
… | |
… | |
680 | \& static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
867 | \& static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
681 | \& { |
868 | \& { |
682 | \& ev_io_stop (w); |
869 | \& ev_io_stop (w); |
683 | \& ev_unloop (loop, EVUNLOOP_ALL); |
870 | \& ev_unloop (loop, EVUNLOOP_ALL); |
684 | \& } |
871 | \& } |
685 | .Ve |
872 | \& |
686 | .PP |
|
|
687 | .Vb 6 |
|
|
688 | \& struct ev_loop *loop = ev_default_loop (0); |
873 | \& struct ev_loop *loop = ev_default_loop (0); |
689 | \& struct ev_io stdin_watcher; |
874 | \& struct ev_io stdin_watcher; |
690 | \& ev_init (&stdin_watcher, my_cb); |
875 | \& ev_init (&stdin_watcher, my_cb); |
691 | \& ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
876 | \& ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
692 | \& ev_io_start (loop, &stdin_watcher); |
877 | \& ev_io_start (loop, &stdin_watcher); |
… | |
… | |
780 | .ie n .IP """EV_FORK""" 4 |
965 | .ie n .IP """EV_FORK""" 4 |
781 | .el .IP "\f(CWEV_FORK\fR" 4 |
966 | .el .IP "\f(CWEV_FORK\fR" 4 |
782 | .IX Item "EV_FORK" |
967 | .IX Item "EV_FORK" |
783 | The event loop has been resumed in the child process after fork (see |
968 | The event loop has been resumed in the child process after fork (see |
784 | \&\f(CW\*(C`ev_fork\*(C'\fR). |
969 | \&\f(CW\*(C`ev_fork\*(C'\fR). |
|
|
970 | .ie n .IP """EV_ASYNC""" 4 |
|
|
971 | .el .IP "\f(CWEV_ASYNC\fR" 4 |
|
|
972 | .IX Item "EV_ASYNC" |
|
|
973 | The given async watcher has been asynchronously notified (see \f(CW\*(C`ev_async\*(C'\fR). |
785 | .ie n .IP """EV_ERROR""" 4 |
974 | .ie n .IP """EV_ERROR""" 4 |
786 | .el .IP "\f(CWEV_ERROR\fR" 4 |
975 | .el .IP "\f(CWEV_ERROR\fR" 4 |
787 | .IX Item "EV_ERROR" |
976 | .IX Item "EV_ERROR" |
788 | An unspecified error has occured, the watcher has been stopped. This might |
977 | An unspecified error has occured, the watcher has been stopped. This might |
789 | happen because the watcher could not be properly started because libev |
978 | happen because the watcher could not be properly started because libev |
… | |
… | |
854 | .IP "bool ev_is_pending (ev_TYPE *watcher)" 4 |
1043 | .IP "bool ev_is_pending (ev_TYPE *watcher)" 4 |
855 | .IX Item "bool ev_is_pending (ev_TYPE *watcher)" |
1044 | .IX Item "bool ev_is_pending (ev_TYPE *watcher)" |
856 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
1045 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
857 | events but its callback has not yet been invoked). As long as a watcher |
1046 | events but its callback has not yet been invoked). As long as a watcher |
858 | is pending (but not active) you must not call an init function on it (but |
1047 | is pending (but not active) you must not call an init function on it (but |
859 | \&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe) and you must make sure the watcher is available to |
1048 | \&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe), you must not change its priority, and you must |
860 | libev (e.g. you cnanot \f(CW\*(C`free ()\*(C'\fR it). |
1049 | make sure the watcher is available to libev (e.g. you cannot \f(CW\*(C`free ()\*(C'\fR |
|
|
1050 | it). |
861 | .IP "callback ev_cb (ev_TYPE *watcher)" 4 |
1051 | .IP "callback ev_cb (ev_TYPE *watcher)" 4 |
862 | .IX Item "callback ev_cb (ev_TYPE *watcher)" |
1052 | .IX Item "callback ev_cb (ev_TYPE *watcher)" |
863 | Returns the callback currently set on the watcher. |
1053 | Returns the callback currently set on the watcher. |
864 | .IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 |
1054 | .IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 |
865 | .IX Item "ev_cb_set (ev_TYPE *watcher, callback)" |
1055 | .IX Item "ev_cb_set (ev_TYPE *watcher, callback)" |
866 | Change the callback. You can change the callback at virtually any time |
1056 | Change the callback. You can change the callback at virtually any time |
867 | (modulo threads). |
1057 | (modulo threads). |
|
|
1058 | .IP "ev_set_priority (ev_TYPE *watcher, priority)" 4 |
|
|
1059 | .IX Item "ev_set_priority (ev_TYPE *watcher, priority)" |
|
|
1060 | .PD 0 |
|
|
1061 | .IP "int ev_priority (ev_TYPE *watcher)" 4 |
|
|
1062 | .IX Item "int ev_priority (ev_TYPE *watcher)" |
|
|
1063 | .PD |
|
|
1064 | Set and query the priority of the watcher. The priority is a small |
|
|
1065 | integer between \f(CW\*(C`EV_MAXPRI\*(C'\fR (default: \f(CW2\fR) and \f(CW\*(C`EV_MINPRI\*(C'\fR |
|
|
1066 | (default: \f(CW\*(C`\-2\*(C'\fR). Pending watchers with higher priority will be invoked |
|
|
1067 | before watchers with lower priority, but priority will not keep watchers |
|
|
1068 | from being executed (except for \f(CW\*(C`ev_idle\*(C'\fR watchers). |
|
|
1069 | .Sp |
|
|
1070 | This means that priorities are \fIonly\fR used for ordering callback |
|
|
1071 | invocation after new events have been received. This is useful, for |
|
|
1072 | example, to reduce latency after idling, or more often, to bind two |
|
|
1073 | watchers on the same event and make sure one is called first. |
|
|
1074 | .Sp |
|
|
1075 | If you need to suppress invocation when higher priority events are pending |
|
|
1076 | you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality. |
|
|
1077 | .Sp |
|
|
1078 | You \fImust not\fR change the priority of a watcher as long as it is active or |
|
|
1079 | pending. |
|
|
1080 | .Sp |
|
|
1081 | The default priority used by watchers when no priority has been set is |
|
|
1082 | always \f(CW0\fR, which is supposed to not be too high and not be too low :). |
|
|
1083 | .Sp |
|
|
1084 | Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is |
|
|
1085 | fine, as long as you do not mind that the priority value you query might |
|
|
1086 | or might not have been adjusted to be within valid range. |
|
|
1087 | .IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4 |
|
|
1088 | .IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)" |
|
|
1089 | 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 |
|
|
1090 | \&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback |
|
|
1091 | can deal with that fact. |
|
|
1092 | .IP "int ev_clear_pending (loop, ev_TYPE *watcher)" 4 |
|
|
1093 | .IX Item "int ev_clear_pending (loop, ev_TYPE *watcher)" |
|
|
1094 | If the watcher is pending, this function returns clears its pending status |
|
|
1095 | and returns its \f(CW\*(C`revents\*(C'\fR bitset (as if its callback was invoked). If the |
|
|
1096 | watcher isn't pending it does nothing and returns \f(CW0\fR. |
868 | .Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" |
1097 | .Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" |
869 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
1098 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
870 | Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change |
1099 | Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change |
871 | and read at any time, libev will completely ignore it. This can be used |
1100 | and read at any time, libev will completely ignore it. This can be used |
872 | to associate arbitrary data with your watcher. If you need more data and |
1101 | to associate arbitrary data with your watcher. If you need more data and |
… | |
… | |
913 | In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more complicated, |
1142 | In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more complicated, |
914 | you need to use \f(CW\*(C`offsetof\*(C'\fR: |
1143 | you need to use \f(CW\*(C`offsetof\*(C'\fR: |
915 | .PP |
1144 | .PP |
916 | .Vb 1 |
1145 | .Vb 1 |
917 | \& #include <stddef.h> |
1146 | \& #include <stddef.h> |
918 | .Ve |
1147 | \& |
919 | .PP |
|
|
920 | .Vb 6 |
|
|
921 | \& static void |
1148 | \& static void |
922 | \& t1_cb (EV_P_ struct ev_timer *w, int revents) |
1149 | \& t1_cb (EV_P_ struct ev_timer *w, int revents) |
923 | \& { |
1150 | \& { |
924 | \& struct my_biggy big = (struct my_biggy * |
1151 | \& struct my_biggy big = (struct my_biggy * |
925 | \& (((char *)w) - offsetof (struct my_biggy, t1)); |
1152 | \& (((char *)w) \- offsetof (struct my_biggy, t1)); |
926 | \& } |
1153 | \& } |
927 | .Ve |
1154 | \& |
928 | .PP |
|
|
929 | .Vb 6 |
|
|
930 | \& static void |
1155 | \& static void |
931 | \& t2_cb (EV_P_ struct ev_timer *w, int revents) |
1156 | \& t2_cb (EV_P_ struct ev_timer *w, int revents) |
932 | \& { |
1157 | \& { |
933 | \& struct my_biggy big = (struct my_biggy * |
1158 | \& struct my_biggy big = (struct my_biggy * |
934 | \& (((char *)w) - offsetof (struct my_biggy, t2)); |
1159 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
935 | \& } |
1160 | \& } |
936 | .Ve |
1161 | .Ve |
937 | .SH "WATCHER TYPES" |
1162 | .SH "WATCHER TYPES" |
938 | .IX Header "WATCHER TYPES" |
1163 | .IX Header "WATCHER TYPES" |
939 | This section describes each watcher in detail, but will not repeat |
1164 | This section describes each watcher in detail, but will not repeat |
… | |
… | |
962 | In general you can register as many read and/or write event watchers per |
1187 | In general you can register as many read and/or write event watchers per |
963 | fd as you want (as long as you don't confuse yourself). Setting all file |
1188 | fd as you want (as long as you don't confuse yourself). Setting all file |
964 | descriptors to non-blocking mode is also usually a good idea (but not |
1189 | descriptors to non-blocking mode is also usually a good idea (but not |
965 | required if you know what you are doing). |
1190 | required if you know what you are doing). |
966 | .PP |
1191 | .PP |
967 | You have to be careful with dup'ed file descriptors, though. Some backends |
|
|
968 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
|
|
969 | descriptors correctly if you register interest in two or more fds pointing |
|
|
970 | to the same underlying file/socket/etc. description (that is, they share |
|
|
971 | the same underlying \*(L"file open\*(R"). |
|
|
972 | .PP |
|
|
973 | If you must do this, then force the use of a known-to-be-good backend |
1192 | If you must do this, then force the use of a known-to-be-good backend |
974 | (at the time of this writing, this includes only \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and |
1193 | (at the time of this writing, this includes only \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and |
975 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR). |
1194 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR). |
976 | .PP |
1195 | .PP |
977 | Another thing you have to watch out for is that it is quite easy to |
1196 | Another thing you have to watch out for is that it is quite easy to |
978 | receive \*(L"spurious\*(R" readyness notifications, that is your callback might |
1197 | receive \*(L"spurious\*(R" readiness notifications, that is your callback might |
979 | be called with \f(CW\*(C`EV_READ\*(C'\fR but a subsequent \f(CW\*(C`read\*(C'\fR(2) will actually block |
1198 | be called with \f(CW\*(C`EV_READ\*(C'\fR but a subsequent \f(CW\*(C`read\*(C'\fR(2) will actually block |
980 | because there is no data. Not only are some backends known to create a |
1199 | because there is no data. Not only are some backends known to create a |
981 | lot of those (for example solaris ports), it is very easy to get into |
1200 | lot of those (for example solaris ports), it is very easy to get into |
982 | this situation even with a relatively standard program structure. Thus |
1201 | this situation even with a relatively standard program structure. Thus |
983 | it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning |
1202 | it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning |
984 | \&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives. |
1203 | \&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives. |
985 | .PP |
1204 | .PP |
986 | If you cannot run the fd in non-blocking mode (for example you should not |
1205 | If you cannot run the fd in non-blocking mode (for example you should not |
987 | play around with an Xlib connection), then you have to seperately re-test |
1206 | play around with an Xlib connection), then you have to seperately re-test |
988 | wether a file descriptor is really ready with a known-to-be good interface |
1207 | whether a file descriptor is really ready with a known-to-be good interface |
989 | such as poll (fortunately in our Xlib example, Xlib already does this on |
1208 | such as poll (fortunately in our Xlib example, Xlib already does this on |
990 | its own, so its quite safe to use). |
1209 | its own, so its quite safe to use). |
|
|
1210 | .PP |
|
|
1211 | \fIThe special problem of disappearing file descriptors\fR |
|
|
1212 | .IX Subsection "The special problem of disappearing file descriptors" |
|
|
1213 | .PP |
|
|
1214 | Some backends (e.g. kqueue, epoll) need to be told about closing a file |
|
|
1215 | descriptor (either by calling \f(CW\*(C`close\*(C'\fR explicitly or by any other means, |
|
|
1216 | such as \f(CW\*(C`dup\*(C'\fR). The reason is that you register interest in some file |
|
|
1217 | descriptor, but when it goes away, the operating system will silently drop |
|
|
1218 | this interest. If another file descriptor with the same number then is |
|
|
1219 | registered with libev, there is no efficient way to see that this is, in |
|
|
1220 | fact, a different file descriptor. |
|
|
1221 | .PP |
|
|
1222 | To avoid having to explicitly tell libev about such cases, libev follows |
|
|
1223 | the following policy: Each time \f(CW\*(C`ev_io_set\*(C'\fR is being called, libev |
|
|
1224 | will assume that this is potentially a new file descriptor, otherwise |
|
|
1225 | it is assumed that the file descriptor stays the same. That means that |
|
|
1226 | 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 |
|
|
1227 | descriptor even if the file descriptor number itself did not change. |
|
|
1228 | .PP |
|
|
1229 | This is how one would do it normally anyway, the important point is that |
|
|
1230 | the libev application should not optimise around libev but should leave |
|
|
1231 | optimisations to libev. |
|
|
1232 | .PP |
|
|
1233 | \fIThe special problem of dup'ed file descriptors\fR |
|
|
1234 | .IX Subsection "The special problem of dup'ed file descriptors" |
|
|
1235 | .PP |
|
|
1236 | Some backends (e.g. epoll), cannot register events for file descriptors, |
|
|
1237 | but only events for the underlying file descriptions. That means when you |
|
|
1238 | have \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors or weirder constellations, and register |
|
|
1239 | events for them, only one file descriptor might actually receive events. |
|
|
1240 | .PP |
|
|
1241 | There is no workaround possible except not registering events |
|
|
1242 | for potentially \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors, or to resort to |
|
|
1243 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
|
|
1244 | .PP |
|
|
1245 | \fIThe special problem of fork\fR |
|
|
1246 | .IX Subsection "The special problem of fork" |
|
|
1247 | .PP |
|
|
1248 | Some backends (epoll, kqueue) do not support \f(CW\*(C`fork ()\*(C'\fR at all or exhibit |
|
|
1249 | useless behaviour. Libev fully supports fork, but needs to be told about |
|
|
1250 | it in the child. |
|
|
1251 | .PP |
|
|
1252 | To support fork in your programs, you either have to call |
|
|
1253 | \&\f(CW\*(C`ev_default_fork ()\*(C'\fR or \f(CW\*(C`ev_loop_fork ()\*(C'\fR after a fork in the child, |
|
|
1254 | enable \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR, or resort to \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or |
|
|
1255 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
|
|
1256 | .PP |
|
|
1257 | \fIThe special problem of \s-1SIGPIPE\s0\fR |
|
|
1258 | .IX Subsection "The special problem of SIGPIPE" |
|
|
1259 | .PP |
|
|
1260 | While not really specific to libev, it is easy to forget about \s-1SIGPIPE:\s0 |
|
|
1261 | when reading from a pipe whose other end has been closed, your program |
|
|
1262 | gets send a \s-1SIGPIPE\s0, which, by default, aborts your program. For most |
|
|
1263 | programs this is sensible behaviour, for daemons, this is usually |
|
|
1264 | undesirable. |
|
|
1265 | .PP |
|
|
1266 | So when you encounter spurious, unexplained daemon exits, make sure you |
|
|
1267 | ignore \s-1SIGPIPE\s0 (and maybe make sure you log the exit status of your daemon |
|
|
1268 | somewhere, as that would have given you a big clue). |
|
|
1269 | .PP |
|
|
1270 | \fIWatcher-Specific Functions\fR |
|
|
1271 | .IX Subsection "Watcher-Specific Functions" |
991 | .IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 |
1272 | .IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 |
992 | .IX Item "ev_io_init (ev_io *, callback, int fd, int events)" |
1273 | .IX Item "ev_io_init (ev_io *, callback, int fd, int events)" |
993 | .PD 0 |
1274 | .PD 0 |
994 | .IP "ev_io_set (ev_io *, int fd, int events)" 4 |
1275 | .IP "ev_io_set (ev_io *, int fd, int events)" 4 |
995 | .IX Item "ev_io_set (ev_io *, int fd, int events)" |
1276 | .IX Item "ev_io_set (ev_io *, int fd, int events)" |
… | |
… | |
1002 | The file descriptor being watched. |
1283 | The file descriptor being watched. |
1003 | .IP "int events [read\-only]" 4 |
1284 | .IP "int events [read\-only]" 4 |
1004 | .IX Item "int events [read-only]" |
1285 | .IX Item "int events [read-only]" |
1005 | The events being watched. |
1286 | The events being watched. |
1006 | .PP |
1287 | .PP |
|
|
1288 | \fIExamples\fR |
|
|
1289 | .IX Subsection "Examples" |
|
|
1290 | .PP |
1007 | Example: Call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well |
1291 | Example: Call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well |
1008 | readable, but only once. Since it is likely line\-buffered, you could |
1292 | readable, but only once. Since it is likely line-buffered, you could |
1009 | attempt to read a whole line in the callback. |
1293 | attempt to read a whole line in the callback. |
1010 | .PP |
1294 | .PP |
1011 | .Vb 6 |
1295 | .Vb 6 |
1012 | \& static void |
1296 | \& static void |
1013 | \& stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1297 | \& stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1014 | \& { |
1298 | \& { |
1015 | \& ev_io_stop (loop, w); |
1299 | \& ev_io_stop (loop, w); |
1016 | \& .. read from stdin here (or from w->fd) and haqndle any I/O errors |
1300 | \& .. read from stdin here (or from w\->fd) and haqndle any I/O errors |
1017 | \& } |
1301 | \& } |
1018 | .Ve |
1302 | \& |
1019 | .PP |
|
|
1020 | .Vb 6 |
|
|
1021 | \& ... |
1303 | \& ... |
1022 | \& struct ev_loop *loop = ev_default_init (0); |
1304 | \& struct ev_loop *loop = ev_default_init (0); |
1023 | \& struct ev_io stdin_readable; |
1305 | \& struct ev_io stdin_readable; |
1024 | \& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1306 | \& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1025 | \& ev_io_start (loop, &stdin_readable); |
1307 | \& ev_io_start (loop, &stdin_readable); |
… | |
… | |
1030 | .IX Subsection "ev_timer - relative and optionally repeating timeouts" |
1312 | .IX Subsection "ev_timer - relative and optionally repeating timeouts" |
1031 | Timer watchers are simple relative timers that generate an event after a |
1313 | Timer watchers are simple relative timers that generate an event after a |
1032 | given time, and optionally repeating in regular intervals after that. |
1314 | given time, and optionally repeating in regular intervals after that. |
1033 | .PP |
1315 | .PP |
1034 | The timers are based on real time, that is, if you register an event that |
1316 | The timers are based on real time, that is, if you register an event that |
1035 | times out after an hour and you reset your system clock to last years |
1317 | times out after an hour and you reset your system clock to january last |
1036 | time, it will still time out after (roughly) and hour. \*(L"Roughly\*(R" because |
1318 | year, it will still time out after (roughly) and hour. \*(L"Roughly\*(R" because |
1037 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1319 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1038 | monotonic clock option helps a lot here). |
1320 | monotonic clock option helps a lot here). |
1039 | .PP |
1321 | .PP |
1040 | The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR |
1322 | The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR |
1041 | time. This is usually the right thing as this timestamp refers to the time |
1323 | time. This is usually the right thing as this timestamp refers to the time |
1042 | of the event triggering whatever timeout you are modifying/starting. If |
1324 | of the event triggering whatever timeout you are modifying/starting. If |
1043 | you suspect event processing to be delayed and you \fIneed\fR to base the timeout |
1325 | you suspect event processing to be delayed and you \fIneed\fR to base the timeout |
1044 | on the current time, use something like this to adjust for this: |
1326 | on the current time, use something like this to adjust for this: |
1045 | .PP |
1327 | .PP |
1046 | .Vb 1 |
1328 | .Vb 1 |
1047 | \& ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
1329 | \& ev_timer_set (&timer, after + ev_now () \- ev_time (), 0.); |
1048 | .Ve |
1330 | .Ve |
1049 | .PP |
1331 | .PP |
1050 | The callback is guarenteed to be invoked only when its timeout has passed, |
1332 | The callback is guarenteed to be invoked only after its timeout has passed, |
1051 | but if multiple timers become ready during the same loop iteration then |
1333 | but if multiple timers become ready during the same loop iteration then |
1052 | order of execution is undefined. |
1334 | order of execution is undefined. |
|
|
1335 | .PP |
|
|
1336 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
1337 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1053 | .IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4 |
1338 | .IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4 |
1054 | .IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" |
1339 | .IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" |
1055 | .PD 0 |
1340 | .PD 0 |
1056 | .IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4 |
1341 | .IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4 |
1057 | .IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" |
1342 | .IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" |
1058 | .PD |
1343 | .PD |
1059 | Configure the timer to trigger after \f(CW\*(C`after\*(C'\fR seconds. If \f(CW\*(C`repeat\*(C'\fR is |
1344 | Configure the timer to trigger after \f(CW\*(C`after\*(C'\fR seconds. If \f(CW\*(C`repeat\*(C'\fR |
1060 | \&\f(CW0.\fR, then it will automatically be stopped. If it is positive, then the |
1345 | is \f(CW0.\fR, then it will automatically be stopped once the timeout is |
1061 | timer will automatically be configured to trigger again \f(CW\*(C`repeat\*(C'\fR seconds |
1346 | reached. If it is positive, then the timer will automatically be |
1062 | later, again, and again, until stopped manually. |
1347 | configured to trigger again \f(CW\*(C`repeat\*(C'\fR seconds later, again, and again, |
|
|
1348 | until stopped manually. |
1063 | .Sp |
1349 | .Sp |
1064 | The timer itself will do a best-effort at avoiding drift, that is, if you |
1350 | The timer itself will do a best-effort at avoiding drift, that is, if |
1065 | configure a timer to trigger every 10 seconds, then it will trigger at |
1351 | you configure a timer to trigger every 10 seconds, then it will normally |
1066 | exactly 10 second intervals. If, however, your program cannot keep up with |
1352 | trigger at exactly 10 second intervals. If, however, your program cannot |
1067 | the timer (because it takes longer than those 10 seconds to do stuff) the |
1353 | keep up with the timer (because it takes longer than those 10 seconds to |
1068 | timer will not fire more than once per event loop iteration. |
1354 | do stuff) the timer will not fire more than once per event loop iteration. |
1069 | .IP "ev_timer_again (loop)" 4 |
1355 | .IP "ev_timer_again (loop, ev_timer *)" 4 |
1070 | .IX Item "ev_timer_again (loop)" |
1356 | .IX Item "ev_timer_again (loop, ev_timer *)" |
1071 | This will act as if the timer timed out and restart it again if it is |
1357 | This will act as if the timer timed out and restart it again if it is |
1072 | repeating. The exact semantics are: |
1358 | repeating. The exact semantics are: |
1073 | .Sp |
1359 | .Sp |
|
|
1360 | If the timer is pending, its pending status is cleared. |
|
|
1361 | .Sp |
1074 | If the timer is started but nonrepeating, stop it. |
1362 | If the timer is started but nonrepeating, stop it (as if it timed out). |
1075 | .Sp |
1363 | .Sp |
1076 | If the timer is repeating, either start it if necessary (with the repeat |
1364 | If the timer is repeating, either start it if necessary (with the |
1077 | value), or reset the running timer to the repeat value. |
1365 | \&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value. |
1078 | .Sp |
1366 | .Sp |
1079 | This sounds a bit complicated, but here is a useful and typical |
1367 | This sounds a bit complicated, but here is a useful and typical |
1080 | example: Imagine you have a tcp connection and you want a so-called |
1368 | example: Imagine you have a tcp connection and you want a so-called idle |
1081 | idle timeout, that is, you want to be called when there have been, |
1369 | timeout, that is, you want to be called when there have been, say, 60 |
1082 | say, 60 seconds of inactivity on the socket. The easiest way to do |
1370 | seconds of inactivity on the socket. The easiest way to do this is to |
1083 | this is to configure an \f(CW\*(C`ev_timer\*(C'\fR with \f(CW\*(C`after\*(C'\fR=\f(CW\*(C`repeat\*(C'\fR=\f(CW60\fR and calling |
1371 | 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 |
1084 | \&\f(CW\*(C`ev_timer_again\*(C'\fR each time you successfully read or write some data. If |
1372 | \&\f(CW\*(C`ev_timer_again\*(C'\fR each time you successfully read or write some data. If |
1085 | you go into an idle state where you do not expect data to travel on the |
1373 | you go into an idle state where you do not expect data to travel on the |
1086 | socket, you can stop the timer, and again will automatically restart it if |
1374 | socket, you can \f(CW\*(C`ev_timer_stop\*(C'\fR the timer, and \f(CW\*(C`ev_timer_again\*(C'\fR will |
1087 | need be. |
1375 | automatically restart it if need be. |
1088 | .Sp |
1376 | .Sp |
1089 | You can also ignore the \f(CW\*(C`after\*(C'\fR value and \f(CW\*(C`ev_timer_start\*(C'\fR altogether |
1377 | That means you can ignore the \f(CW\*(C`after\*(C'\fR value and \f(CW\*(C`ev_timer_start\*(C'\fR |
1090 | and only ever use the \f(CW\*(C`repeat\*(C'\fR value: |
1378 | altogether and only ever use the \f(CW\*(C`repeat\*(C'\fR value and \f(CW\*(C`ev_timer_again\*(C'\fR: |
1091 | .Sp |
1379 | .Sp |
1092 | .Vb 8 |
1380 | .Vb 8 |
1093 | \& ev_timer_init (timer, callback, 0., 5.); |
1381 | \& ev_timer_init (timer, callback, 0., 5.); |
1094 | \& ev_timer_again (loop, timer); |
1382 | \& ev_timer_again (loop, timer); |
1095 | \& ... |
1383 | \& ... |
1096 | \& timer->again = 17.; |
1384 | \& timer\->again = 17.; |
1097 | \& ev_timer_again (loop, timer); |
1385 | \& ev_timer_again (loop, timer); |
1098 | \& ... |
1386 | \& ... |
1099 | \& timer->again = 10.; |
1387 | \& timer\->again = 10.; |
1100 | \& ev_timer_again (loop, timer); |
1388 | \& ev_timer_again (loop, timer); |
1101 | .Ve |
1389 | .Ve |
1102 | .Sp |
1390 | .Sp |
1103 | This is more efficient then stopping/starting the timer eahc time you want |
1391 | This is more slightly efficient then stopping/starting the timer each time |
1104 | to modify its timeout value. |
1392 | you want to modify its timeout value. |
1105 | .IP "ev_tstamp repeat [read\-write]" 4 |
1393 | .IP "ev_tstamp repeat [read\-write]" 4 |
1106 | .IX Item "ev_tstamp repeat [read-write]" |
1394 | .IX Item "ev_tstamp repeat [read-write]" |
1107 | The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out |
1395 | The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out |
1108 | or \f(CW\*(C`ev_timer_again\*(C'\fR is called and determines the next timeout (if any), |
1396 | or \f(CW\*(C`ev_timer_again\*(C'\fR is called and determines the next timeout (if any), |
1109 | which is also when any modifications are taken into account. |
1397 | which is also when any modifications are taken into account. |
|
|
1398 | .PP |
|
|
1399 | \fIExamples\fR |
|
|
1400 | .IX Subsection "Examples" |
1110 | .PP |
1401 | .PP |
1111 | Example: Create a timer that fires after 60 seconds. |
1402 | Example: Create a timer that fires after 60 seconds. |
1112 | .PP |
1403 | .PP |
1113 | .Vb 5 |
1404 | .Vb 5 |
1114 | \& static void |
1405 | \& static void |
1115 | \& one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1406 | \& one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1116 | \& { |
1407 | \& { |
1117 | \& .. one minute over, w is actually stopped right here |
1408 | \& .. one minute over, w is actually stopped right here |
1118 | \& } |
1409 | \& } |
1119 | .Ve |
1410 | \& |
1120 | .PP |
|
|
1121 | .Vb 3 |
|
|
1122 | \& struct ev_timer mytimer; |
1411 | \& struct ev_timer mytimer; |
1123 | \& ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
1412 | \& ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
1124 | \& ev_timer_start (loop, &mytimer); |
1413 | \& ev_timer_start (loop, &mytimer); |
1125 | .Ve |
1414 | .Ve |
1126 | .PP |
1415 | .PP |
… | |
… | |
1131 | \& static void |
1420 | \& static void |
1132 | \& timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1421 | \& timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1133 | \& { |
1422 | \& { |
1134 | \& .. ten seconds without any activity |
1423 | \& .. ten seconds without any activity |
1135 | \& } |
1424 | \& } |
1136 | .Ve |
1425 | \& |
1137 | .PP |
|
|
1138 | .Vb 4 |
|
|
1139 | \& struct ev_timer mytimer; |
1426 | \& struct ev_timer mytimer; |
1140 | \& ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1427 | \& ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1141 | \& ev_timer_again (&mytimer); /* start timer */ |
1428 | \& ev_timer_again (&mytimer); /* start timer */ |
1142 | \& ev_loop (loop, 0); |
1429 | \& ev_loop (loop, 0); |
1143 | .Ve |
1430 | \& |
1144 | .PP |
|
|
1145 | .Vb 3 |
|
|
1146 | \& // and in some piece of code that gets executed on any "activity": |
1431 | \& // and in some piece of code that gets executed on any "activity": |
1147 | \& // reset the timeout to start ticking again at 10 seconds |
1432 | \& // reset the timeout to start ticking again at 10 seconds |
1148 | \& ev_timer_again (&mytimer); |
1433 | \& ev_timer_again (&mytimer); |
1149 | .Ve |
1434 | .Ve |
1150 | .ie n .Sh """ev_periodic"" \- to cron or not to cron?" |
1435 | .ie n .Sh """ev_periodic"" \- to cron or not to cron?" |
… | |
… | |
1153 | Periodic watchers are also timers of a kind, but they are very versatile |
1438 | Periodic watchers are also timers of a kind, but they are very versatile |
1154 | (and unfortunately a bit complex). |
1439 | (and unfortunately a bit complex). |
1155 | .PP |
1440 | .PP |
1156 | Unlike \f(CW\*(C`ev_timer\*(C'\fR's, they are not based on real time (or relative time) |
1441 | Unlike \f(CW\*(C`ev_timer\*(C'\fR's, they are not based on real time (or relative time) |
1157 | but on wallclock time (absolute time). You can tell a periodic watcher |
1442 | but on wallclock time (absolute time). You can tell a periodic watcher |
1158 | to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a |
1443 | to trigger after some specific point in time. For example, if you tell a |
1159 | periodic watcher to trigger in 10 seconds (by specifiying e.g. \f(CW\*(C`ev_now () |
1444 | periodic watcher to trigger in 10 seconds (by specifiying e.g. \f(CW\*(C`ev_now () |
1160 | + 10.\*(C'\fR) and then reset your system clock to the last year, then it will |
1445 | + 10.\*(C'\fR, that is, an absolute time not a delay) and then reset your system |
|
|
1446 | clock to january of the previous year, then it will take more than year |
1161 | take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger |
1447 | to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would still trigger |
1162 | roughly 10 seconds later and of course not if you reset your system time |
1448 | roughly 10 seconds later as it uses a relative timeout). |
1163 | again). |
|
|
1164 | .PP |
1449 | .PP |
1165 | They can also be used to implement vastly more complex timers, such as |
1450 | \&\f(CW\*(C`ev_periodic\*(C'\fRs can also be used to implement vastly more complex timers, |
1166 | triggering an event on eahc midnight, local time. |
1451 | such as triggering an event on each \*(L"midnight, local time\*(R", or other |
|
|
1452 | complicated, rules. |
1167 | .PP |
1453 | .PP |
1168 | As with timers, the callback is guarenteed to be invoked only when the |
1454 | As with timers, the callback is guarenteed to be invoked only when the |
1169 | time (\f(CW\*(C`at\*(C'\fR) has been passed, but if multiple periodic timers become ready |
1455 | time (\f(CW\*(C`at\*(C'\fR) has passed, but if multiple periodic timers become ready |
1170 | during the same loop iteration then order of execution is undefined. |
1456 | during the same loop iteration then order of execution is undefined. |
|
|
1457 | .PP |
|
|
1458 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
1459 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1171 | .IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4 |
1460 | .IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4 |
1172 | .IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" |
1461 | .IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" |
1173 | .PD 0 |
1462 | .PD 0 |
1174 | .IP "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 4 |
1463 | .IP "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 4 |
1175 | .IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" |
1464 | .IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" |
1176 | .PD |
1465 | .PD |
1177 | Lots of arguments, lets sort it out... There are basically three modes of |
1466 | Lots of arguments, lets sort it out... There are basically three modes of |
1178 | operation, and we will explain them from simplest to complex: |
1467 | operation, and we will explain them from simplest to complex: |
1179 | .RS 4 |
1468 | .RS 4 |
|
|
1469 | .IP "\(bu" 4 |
1180 | .IP "* absolute timer (interval = reschedule_cb = 0)" 4 |
1470 | absolute timer (at = time, interval = reschedule_cb = 0) |
1181 | .IX Item "absolute timer (interval = reschedule_cb = 0)" |
1471 | .Sp |
1182 | In this configuration the watcher triggers an event at the wallclock time |
1472 | In this configuration the watcher triggers an event after the wallclock |
1183 | \&\f(CW\*(C`at\*(C'\fR and doesn't repeat. It will not adjust when a time jump occurs, |
1473 | time \f(CW\*(C`at\*(C'\fR has passed and doesn't repeat. It will not adjust when a time |
1184 | that is, if it is to be run at January 1st 2011 then it will run when the |
1474 | jump occurs, that is, if it is to be run at January 1st 2011 then it will |
1185 | system time reaches or surpasses this time. |
1475 | run when the system time reaches or surpasses this time. |
|
|
1476 | .IP "\(bu" 4 |
1186 | .IP "* non-repeating interval timer (interval > 0, reschedule_cb = 0)" 4 |
1477 | repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
1187 | .IX Item "non-repeating interval timer (interval > 0, reschedule_cb = 0)" |
1478 | .Sp |
1188 | In this mode the watcher will always be scheduled to time out at the next |
1479 | In this mode the watcher will always be scheduled to time out at the next |
1189 | \&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N) and then repeat, regardless |
1480 | \&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N, which can also be negative) |
1190 | of any time jumps. |
1481 | and then repeat, regardless of any time jumps. |
1191 | .Sp |
1482 | .Sp |
1192 | This can be used to create timers that do not drift with respect to system |
1483 | This can be used to create timers that do not drift with respect to system |
1193 | time: |
1484 | time, for example, here is a \f(CW\*(C`ev_periodic\*(C'\fR that triggers each hour, on |
|
|
1485 | the hour: |
1194 | .Sp |
1486 | .Sp |
1195 | .Vb 1 |
1487 | .Vb 1 |
1196 | \& ev_periodic_set (&periodic, 0., 3600., 0); |
1488 | \& ev_periodic_set (&periodic, 0., 3600., 0); |
1197 | .Ve |
1489 | .Ve |
1198 | .Sp |
1490 | .Sp |
… | |
… | |
1202 | by 3600. |
1494 | by 3600. |
1203 | .Sp |
1495 | .Sp |
1204 | Another way to think about it (for the mathematically inclined) is that |
1496 | Another way to think about it (for the mathematically inclined) is that |
1205 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
1497 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
1206 | time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps. |
1498 | time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps. |
1207 | .IP "* manual reschedule mode (reschedule_cb = callback)" 4 |
1499 | .Sp |
1208 | .IX Item "manual reschedule mode (reschedule_cb = callback)" |
1500 | For numerical stability it is preferable that the \f(CW\*(C`at\*(C'\fR value is near |
|
|
1501 | \&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for |
|
|
1502 | this value, and in fact is often specified as zero. |
|
|
1503 | .Sp |
|
|
1504 | Note also that there is an upper limit to how often a timer can fire (cpu |
|
|
1505 | speed for example), so if \f(CW\*(C`interval\*(C'\fR is very small then timing stability |
|
|
1506 | will of course detoriate. Libev itself tries to be exact to be about one |
|
|
1507 | millisecond (if the \s-1OS\s0 supports it and the machine is fast enough). |
|
|
1508 | .IP "\(bu" 4 |
|
|
1509 | manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
|
|
1510 | .Sp |
1209 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being |
1511 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being |
1210 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1512 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1211 | reschedule callback will be called with the watcher as first, and the |
1513 | reschedule callback will be called with the watcher as first, and the |
1212 | current time as second argument. |
1514 | current time as second argument. |
1213 | .Sp |
1515 | .Sp |
1214 | \&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, |
1516 | \&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, |
1215 | ever, or make any event loop modifications\fR. If you need to stop it, |
1517 | ever, or make \s-1ANY\s0 event loop modifications whatsoever\fR. |
1216 | return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop it afterwards (e.g. by |
|
|
1217 | starting a prepare watcher). |
|
|
1218 | .Sp |
1518 | .Sp |
|
|
1519 | If you need to stop it, return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop |
|
|
1520 | it afterwards (e.g. by starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is the |
|
|
1521 | only event loop modification you are allowed to do). |
|
|
1522 | .Sp |
1219 | Its prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1523 | The callback prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(struct ev_periodic |
1220 | ev_tstamp now)\*(C'\fR, e.g.: |
1524 | *w, ev_tstamp now)\*(C'\fR, e.g.: |
1221 | .Sp |
1525 | .Sp |
1222 | .Vb 4 |
1526 | .Vb 4 |
1223 | \& static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
1527 | \& static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
1224 | \& { |
1528 | \& { |
1225 | \& return now + 60.; |
1529 | \& return now + 60.; |
… | |
… | |
1229 | It must return the next time to trigger, based on the passed time value |
1533 | It must return the next time to trigger, based on the passed time value |
1230 | (that is, the lowest time value larger than to the second argument). It |
1534 | (that is, the lowest time value larger than to the second argument). It |
1231 | will usually be called just before the callback will be triggered, but |
1535 | will usually be called just before the callback will be triggered, but |
1232 | might be called at other times, too. |
1536 | might be called at other times, too. |
1233 | .Sp |
1537 | .Sp |
1234 | \&\s-1NOTE:\s0 \fIThis callback must always return a time that is later than the |
1538 | \&\s-1NOTE:\s0 \fIThis callback must always return a time that is higher than or |
1235 | 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. |
1539 | equal to the passed \f(CI\*(C`now\*(C'\fI value\fR. |
1236 | .Sp |
1540 | .Sp |
1237 | This can be used to create very complex timers, such as a timer that |
1541 | This can be used to create very complex timers, such as a timer that |
1238 | triggers on each midnight, local time. To do this, you would calculate the |
1542 | triggers on \*(L"next midnight, local time\*(R". To do this, you would calculate the |
1239 | next midnight after \f(CW\*(C`now\*(C'\fR and return the timestamp value for this. How |
1543 | next midnight after \f(CW\*(C`now\*(C'\fR and return the timestamp value for this. How |
1240 | you do this is, again, up to you (but it is not trivial, which is the main |
1544 | you do this is, again, up to you (but it is not trivial, which is the main |
1241 | reason I omitted it as an example). |
1545 | reason I omitted it as an example). |
1242 | .RE |
1546 | .RE |
1243 | .RS 4 |
1547 | .RS 4 |
… | |
… | |
1246 | .IX Item "ev_periodic_again (loop, ev_periodic *)" |
1550 | .IX Item "ev_periodic_again (loop, ev_periodic *)" |
1247 | Simply stops and restarts the periodic watcher again. This is only useful |
1551 | Simply stops and restarts the periodic watcher again. This is only useful |
1248 | when you changed some parameters or the reschedule callback would return |
1552 | when you changed some parameters or the reschedule callback would return |
1249 | a different time than the last time it was called (e.g. in a crond like |
1553 | a different time than the last time it was called (e.g. in a crond like |
1250 | program when the crontabs have changed). |
1554 | program when the crontabs have changed). |
|
|
1555 | .IP "ev_tstamp ev_periodic_at (ev_periodic *)" 4 |
|
|
1556 | .IX Item "ev_tstamp ev_periodic_at (ev_periodic *)" |
|
|
1557 | When active, returns the absolute time that the watcher is supposed to |
|
|
1558 | trigger next. |
|
|
1559 | .IP "ev_tstamp offset [read\-write]" 4 |
|
|
1560 | .IX Item "ev_tstamp offset [read-write]" |
|
|
1561 | When repeating, this contains the offset value, otherwise this is the |
|
|
1562 | absolute point in time (the \f(CW\*(C`at\*(C'\fR value passed to \f(CW\*(C`ev_periodic_set\*(C'\fR). |
|
|
1563 | .Sp |
|
|
1564 | Can be modified any time, but changes only take effect when the periodic |
|
|
1565 | timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. |
1251 | .IP "ev_tstamp interval [read\-write]" 4 |
1566 | .IP "ev_tstamp interval [read\-write]" 4 |
1252 | .IX Item "ev_tstamp interval [read-write]" |
1567 | .IX Item "ev_tstamp interval [read-write]" |
1253 | The current interval value. Can be modified any time, but changes only |
1568 | The current interval value. Can be modified any time, but changes only |
1254 | take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being |
1569 | take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being |
1255 | called. |
1570 | called. |
… | |
… | |
1257 | .IX Item "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]" |
1572 | .IX Item "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]" |
1258 | The current reschedule callback, or \f(CW0\fR, if this functionality is |
1573 | The current reschedule callback, or \f(CW0\fR, if this functionality is |
1259 | switched off. Can be changed any time, but changes only take effect when |
1574 | switched off. Can be changed any time, but changes only take effect when |
1260 | the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. |
1575 | the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. |
1261 | .PP |
1576 | .PP |
|
|
1577 | \fIExamples\fR |
|
|
1578 | .IX Subsection "Examples" |
|
|
1579 | .PP |
1262 | Example: Call a callback every hour, or, more precisely, whenever the |
1580 | Example: Call a callback every hour, or, more precisely, whenever the |
1263 | system clock is divisible by 3600. The callback invocation times have |
1581 | system clock is divisible by 3600. The callback invocation times have |
1264 | potentially a lot of jittering, but good long-term stability. |
1582 | potentially a lot of jittering, but good long-term stability. |
1265 | .PP |
1583 | .PP |
1266 | .Vb 5 |
1584 | .Vb 5 |
1267 | \& static void |
1585 | \& static void |
1268 | \& clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1586 | \& clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1269 | \& { |
1587 | \& { |
1270 | \& ... its now a full hour (UTC, or TAI or whatever your clock follows) |
1588 | \& ... its now a full hour (UTC, or TAI or whatever your clock follows) |
1271 | \& } |
1589 | \& } |
1272 | .Ve |
1590 | \& |
1273 | .PP |
|
|
1274 | .Vb 3 |
|
|
1275 | \& struct ev_periodic hourly_tick; |
1591 | \& struct ev_periodic hourly_tick; |
1276 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1592 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1277 | \& ev_periodic_start (loop, &hourly_tick); |
1593 | \& ev_periodic_start (loop, &hourly_tick); |
1278 | .Ve |
1594 | .Ve |
1279 | .PP |
1595 | .PP |
1280 | Example: The same as above, but use a reschedule callback to do it: |
1596 | Example: The same as above, but use a reschedule callback to do it: |
1281 | .PP |
1597 | .PP |
1282 | .Vb 1 |
1598 | .Vb 1 |
1283 | \& #include <math.h> |
1599 | \& #include <math.h> |
1284 | .Ve |
1600 | \& |
1285 | .PP |
|
|
1286 | .Vb 5 |
|
|
1287 | \& static ev_tstamp |
1601 | \& static ev_tstamp |
1288 | \& my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
1602 | \& my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
1289 | \& { |
1603 | \& { |
1290 | \& return fmod (now, 3600.) + 3600.; |
1604 | \& return fmod (now, 3600.) + 3600.; |
1291 | \& } |
1605 | \& } |
1292 | .Ve |
1606 | \& |
1293 | .PP |
|
|
1294 | .Vb 1 |
|
|
1295 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1607 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1296 | .Ve |
1608 | .Ve |
1297 | .PP |
1609 | .PP |
1298 | Example: Call a callback every hour, starting now: |
1610 | Example: Call a callback every hour, starting now: |
1299 | .PP |
1611 | .PP |
… | |
… | |
1315 | first watcher gets started will libev actually register a signal watcher |
1627 | first watcher gets started will libev actually register a signal watcher |
1316 | with the kernel (thus it coexists with your own signal handlers as long |
1628 | with the kernel (thus it coexists with your own signal handlers as long |
1317 | as you don't register any with libev). Similarly, when the last signal |
1629 | as you don't register any with libev). Similarly, when the last signal |
1318 | watcher for a signal is stopped libev will reset the signal handler to |
1630 | watcher for a signal is stopped libev will reset the signal handler to |
1319 | \&\s-1SIG_DFL\s0 (regardless of what it was set to before). |
1631 | \&\s-1SIG_DFL\s0 (regardless of what it was set to before). |
|
|
1632 | .PP |
|
|
1633 | If possible and supported, libev will install its handlers with |
|
|
1634 | \&\f(CW\*(C`SA_RESTART\*(C'\fR behaviour enabled, so syscalls should not be unduly |
|
|
1635 | interrupted. If you have a problem with syscalls getting interrupted by |
|
|
1636 | signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher and unblock |
|
|
1637 | them in an \f(CW\*(C`ev_prepare\*(C'\fR watcher. |
|
|
1638 | .PP |
|
|
1639 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
1640 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1320 | .IP "ev_signal_init (ev_signal *, callback, int signum)" 4 |
1641 | .IP "ev_signal_init (ev_signal *, callback, int signum)" 4 |
1321 | .IX Item "ev_signal_init (ev_signal *, callback, int signum)" |
1642 | .IX Item "ev_signal_init (ev_signal *, callback, int signum)" |
1322 | .PD 0 |
1643 | .PD 0 |
1323 | .IP "ev_signal_set (ev_signal *, int signum)" 4 |
1644 | .IP "ev_signal_set (ev_signal *, int signum)" 4 |
1324 | .IX Item "ev_signal_set (ev_signal *, int signum)" |
1645 | .IX Item "ev_signal_set (ev_signal *, int signum)" |
… | |
… | |
1326 | Configures the watcher to trigger on the given signal number (usually one |
1647 | Configures the watcher to trigger on the given signal number (usually one |
1327 | of the \f(CW\*(C`SIGxxx\*(C'\fR constants). |
1648 | of the \f(CW\*(C`SIGxxx\*(C'\fR constants). |
1328 | .IP "int signum [read\-only]" 4 |
1649 | .IP "int signum [read\-only]" 4 |
1329 | .IX Item "int signum [read-only]" |
1650 | .IX Item "int signum [read-only]" |
1330 | The signal the watcher watches out for. |
1651 | The signal the watcher watches out for. |
|
|
1652 | .PP |
|
|
1653 | \fIExamples\fR |
|
|
1654 | .IX Subsection "Examples" |
|
|
1655 | .PP |
|
|
1656 | Example: Try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0. |
|
|
1657 | .PP |
|
|
1658 | .Vb 5 |
|
|
1659 | \& static void |
|
|
1660 | \& sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
|
|
1661 | \& { |
|
|
1662 | \& ev_unloop (loop, EVUNLOOP_ALL); |
|
|
1663 | \& } |
|
|
1664 | \& |
|
|
1665 | \& struct ev_signal signal_watcher; |
|
|
1666 | \& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
|
|
1667 | \& ev_signal_start (loop, &sigint_cb); |
|
|
1668 | .Ve |
1331 | .ie n .Sh """ev_child"" \- watch out for process status changes" |
1669 | .ie n .Sh """ev_child"" \- watch out for process status changes" |
1332 | .el .Sh "\f(CWev_child\fP \- watch out for process status changes" |
1670 | .el .Sh "\f(CWev_child\fP \- watch out for process status changes" |
1333 | .IX Subsection "ev_child - watch out for process status changes" |
1671 | .IX Subsection "ev_child - watch out for process status changes" |
1334 | Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to |
1672 | Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to |
1335 | some child status changes (most typically when a child of yours dies). |
1673 | some child status changes (most typically when a child of yours dies). It |
|
|
1674 | is permissible to install a child watcher \fIafter\fR the child has been |
|
|
1675 | forked (which implies it might have already exited), as long as the event |
|
|
1676 | loop isn't entered (or is continued from a watcher). |
|
|
1677 | .PP |
|
|
1678 | Only the default event loop is capable of handling signals, and therefore |
|
|
1679 | you can only rgeister child watchers in the default event loop. |
|
|
1680 | .PP |
|
|
1681 | \fIProcess Interaction\fR |
|
|
1682 | .IX Subsection "Process Interaction" |
|
|
1683 | .PP |
|
|
1684 | Libev grabs \f(CW\*(C`SIGCHLD\*(C'\fR as soon as the default event loop is |
|
|
1685 | initialised. This is necessary to guarantee proper behaviour even if |
|
|
1686 | the first child watcher is started after the child exits. The occurance |
|
|
1687 | of \f(CW\*(C`SIGCHLD\*(C'\fR is recorded asynchronously, but child reaping is done |
|
|
1688 | synchronously as part of the event loop processing. Libev always reaps all |
|
|
1689 | children, even ones not watched. |
|
|
1690 | .PP |
|
|
1691 | \fIOverriding the Built-In Processing\fR |
|
|
1692 | .IX Subsection "Overriding the Built-In Processing" |
|
|
1693 | .PP |
|
|
1694 | Libev offers no special support for overriding the built-in child |
|
|
1695 | processing, but if your application collides with libev's default child |
|
|
1696 | handler, you can override it easily by installing your own handler for |
|
|
1697 | \&\f(CW\*(C`SIGCHLD\*(C'\fR after initialising the default loop, and making sure the |
|
|
1698 | default loop never gets destroyed. You are encouraged, however, to use an |
|
|
1699 | event-based approach to child reaping and thus use libev's support for |
|
|
1700 | that, so other libev users can use \f(CW\*(C`ev_child\*(C'\fR watchers freely. |
|
|
1701 | .PP |
|
|
1702 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
1703 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1336 | .IP "ev_child_init (ev_child *, callback, int pid)" 4 |
1704 | .IP "ev_child_init (ev_child *, callback, int pid, int trace)" 4 |
1337 | .IX Item "ev_child_init (ev_child *, callback, int pid)" |
1705 | .IX Item "ev_child_init (ev_child *, callback, int pid, int trace)" |
1338 | .PD 0 |
1706 | .PD 0 |
1339 | .IP "ev_child_set (ev_child *, int pid)" 4 |
1707 | .IP "ev_child_set (ev_child *, int pid, int trace)" 4 |
1340 | .IX Item "ev_child_set (ev_child *, int pid)" |
1708 | .IX Item "ev_child_set (ev_child *, int pid, int trace)" |
1341 | .PD |
1709 | .PD |
1342 | Configures the watcher to wait for status changes of process \f(CW\*(C`pid\*(C'\fR (or |
1710 | Configures the watcher to wait for status changes of process \f(CW\*(C`pid\*(C'\fR (or |
1343 | \&\fIany\fR process if \f(CW\*(C`pid\*(C'\fR is specified as \f(CW0\fR). The callback can look |
1711 | \&\fIany\fR process if \f(CW\*(C`pid\*(C'\fR is specified as \f(CW0\fR). The callback can look |
1344 | at the \f(CW\*(C`rstatus\*(C'\fR member of the \f(CW\*(C`ev_child\*(C'\fR watcher structure to see |
1712 | at the \f(CW\*(C`rstatus\*(C'\fR member of the \f(CW\*(C`ev_child\*(C'\fR watcher structure to see |
1345 | the status word (use the macros from \f(CW\*(C`sys/wait.h\*(C'\fR and see your systems |
1713 | the status word (use the macros from \f(CW\*(C`sys/wait.h\*(C'\fR and see your systems |
1346 | \&\f(CW\*(C`waitpid\*(C'\fR documentation). The \f(CW\*(C`rpid\*(C'\fR member contains the pid of the |
1714 | \&\f(CW\*(C`waitpid\*(C'\fR documentation). The \f(CW\*(C`rpid\*(C'\fR member contains the pid of the |
1347 | process causing the status change. |
1715 | process causing the status change. \f(CW\*(C`trace\*(C'\fR must be either \f(CW0\fR (only |
|
|
1716 | activate the watcher when the process terminates) or \f(CW1\fR (additionally |
|
|
1717 | activate the watcher when the process is stopped or continued). |
1348 | .IP "int pid [read\-only]" 4 |
1718 | .IP "int pid [read\-only]" 4 |
1349 | .IX Item "int pid [read-only]" |
1719 | .IX Item "int pid [read-only]" |
1350 | The process id this watcher watches out for, or \f(CW0\fR, meaning any process id. |
1720 | The process id this watcher watches out for, or \f(CW0\fR, meaning any process id. |
1351 | .IP "int rpid [read\-write]" 4 |
1721 | .IP "int rpid [read\-write]" 4 |
1352 | .IX Item "int rpid [read-write]" |
1722 | .IX Item "int rpid [read-write]" |
… | |
… | |
1354 | .IP "int rstatus [read\-write]" 4 |
1724 | .IP "int rstatus [read\-write]" 4 |
1355 | .IX Item "int rstatus [read-write]" |
1725 | .IX Item "int rstatus [read-write]" |
1356 | The process exit/trace status caused by \f(CW\*(C`rpid\*(C'\fR (see your systems |
1726 | The process exit/trace status caused by \f(CW\*(C`rpid\*(C'\fR (see your systems |
1357 | \&\f(CW\*(C`waitpid\*(C'\fR and \f(CW\*(C`sys/wait.h\*(C'\fR documentation for details). |
1727 | \&\f(CW\*(C`waitpid\*(C'\fR and \f(CW\*(C`sys/wait.h\*(C'\fR documentation for details). |
1358 | .PP |
1728 | .PP |
1359 | Example: Try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0. |
1729 | \fIExamples\fR |
|
|
1730 | .IX Subsection "Examples" |
1360 | .PP |
1731 | .PP |
|
|
1732 | Example: \f(CW\*(C`fork()\*(C'\fR a new process and install a child handler to wait for |
|
|
1733 | its completion. |
|
|
1734 | .PP |
1361 | .Vb 5 |
1735 | .Vb 1 |
|
|
1736 | \& ev_child cw; |
|
|
1737 | \& |
1362 | \& static void |
1738 | \& static void |
1363 | \& sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1739 | \& child_cb (EV_P_ struct ev_child *w, int revents) |
1364 | \& { |
1740 | \& { |
1365 | \& ev_unloop (loop, EVUNLOOP_ALL); |
1741 | \& ev_child_stop (EV_A_ w); |
|
|
1742 | \& printf ("process %d exited with status %x\en", w\->rpid, w\->rstatus); |
1366 | \& } |
1743 | \& } |
1367 | .Ve |
1744 | \& |
1368 | .PP |
1745 | \& pid_t pid = fork (); |
1369 | .Vb 3 |
1746 | \& |
1370 | \& struct ev_signal signal_watcher; |
1747 | \& if (pid < 0) |
1371 | \& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1748 | \& // error |
1372 | \& ev_signal_start (loop, &sigint_cb); |
1749 | \& else if (pid == 0) |
|
|
1750 | \& { |
|
|
1751 | \& // the forked child executes here |
|
|
1752 | \& exit (1); |
|
|
1753 | \& } |
|
|
1754 | \& else |
|
|
1755 | \& { |
|
|
1756 | \& ev_child_init (&cw, child_cb, pid, 0); |
|
|
1757 | \& ev_child_start (EV_DEFAULT_ &cw); |
|
|
1758 | \& } |
1373 | .Ve |
1759 | .Ve |
1374 | .ie n .Sh """ev_stat"" \- did the file attributes just change?" |
1760 | .ie n .Sh """ev_stat"" \- did the file attributes just change?" |
1375 | .el .Sh "\f(CWev_stat\fP \- did the file attributes just change?" |
1761 | .el .Sh "\f(CWev_stat\fP \- did the file attributes just change?" |
1376 | .IX Subsection "ev_stat - did the file attributes just change?" |
1762 | .IX Subsection "ev_stat - did the file attributes just change?" |
1377 | This watches a filesystem path for attribute changes. That is, it calls |
1763 | This watches a filesystem path for attribute changes. That is, it calls |
… | |
… | |
1382 | not exist\*(R" is a status change like any other. The condition \*(L"path does |
1768 | not exist\*(R" is a status change like any other. The condition \*(L"path does |
1383 | not exist\*(R" is signified by the \f(CW\*(C`st_nlink\*(C'\fR field being zero (which is |
1769 | not exist\*(R" is signified by the \f(CW\*(C`st_nlink\*(C'\fR field being zero (which is |
1384 | otherwise always forced to be at least one) and all the other fields of |
1770 | otherwise always forced to be at least one) and all the other fields of |
1385 | the stat buffer having unspecified contents. |
1771 | the stat buffer having unspecified contents. |
1386 | .PP |
1772 | .PP |
|
|
1773 | The path \fIshould\fR be absolute and \fImust not\fR end in a slash. If it is |
|
|
1774 | relative and your working directory changes, the behaviour is undefined. |
|
|
1775 | .PP |
1387 | Since there is no standard to do this, the portable implementation simply |
1776 | Since there is no standard to do this, the portable implementation simply |
1388 | calls \f(CW\*(C`stat (2)\*(C'\fR regulalry on the path to see if it changed somehow. You |
1777 | calls \f(CW\*(C`stat (2)\*(C'\fR regularly on the path to see if it changed somehow. You |
1389 | can specify a recommended polling interval for this case. If you specify |
1778 | can specify a recommended polling interval for this case. If you specify |
1390 | a polling interval of \f(CW0\fR (highly recommended!) then a \fIsuitable, |
1779 | a polling interval of \f(CW0\fR (highly recommended!) then a \fIsuitable, |
1391 | unspecified default\fR value will be used (which you can expect to be around |
1780 | unspecified default\fR value will be used (which you can expect to be around |
1392 | five seconds, although this might change dynamically). Libev will also |
1781 | five seconds, although this might change dynamically). Libev will also |
1393 | impose a minimum interval which is currently around \f(CW0.1\fR, but thats |
1782 | impose a minimum interval which is currently around \f(CW0.1\fR, but thats |
1394 | usually overkill. |
1783 | usually overkill. |
1395 | .PP |
1784 | .PP |
1396 | This watcher type is not meant for massive numbers of stat watchers, |
1785 | This watcher type is not meant for massive numbers of stat watchers, |
1397 | as even with OS-supported change notifications, this can be |
1786 | as even with OS-supported change notifications, this can be |
1398 | resource\-intensive. |
1787 | resource-intensive. |
1399 | .PP |
1788 | .PP |
1400 | At the time of this writing, no specific \s-1OS\s0 backends are implemented, but |
1789 | At the time of this writing, only the Linux inotify interface is |
1401 | if demand increases, at least a kqueue and inotify backend will be added. |
1790 | implemented (implementing kqueue support is left as an exercise for the |
|
|
1791 | reader, note, however, that the author sees no way of implementing ev_stat |
|
|
1792 | semantics with kqueue). Inotify will be used to give hints only and should |
|
|
1793 | not change the semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers, which means that libev |
|
|
1794 | sometimes needs to fall back to regular polling again even with inotify, |
|
|
1795 | but changes are usually detected immediately, and if the file exists there |
|
|
1796 | will be no polling. |
|
|
1797 | .PP |
|
|
1798 | \fI\s-1ABI\s0 Issues (Largefile Support)\fR |
|
|
1799 | .IX Subsection "ABI Issues (Largefile Support)" |
|
|
1800 | .PP |
|
|
1801 | Libev by default (unless the user overrides this) uses the default |
|
|
1802 | compilation environment, which means that on systems with optionally |
|
|
1803 | disabled large file support, you get the 32 bit version of the stat |
|
|
1804 | structure. When using the library from programs that change the \s-1ABI\s0 to |
|
|
1805 | use 64 bit file offsets the programs will fail. In that case you have to |
|
|
1806 | compile libev with the same flags to get binary compatibility. This is |
|
|
1807 | obviously the case with any flags that change the \s-1ABI\s0, but the problem is |
|
|
1808 | most noticably with ev_stat and largefile support. |
|
|
1809 | .PP |
|
|
1810 | \fIInotify\fR |
|
|
1811 | .IX Subsection "Inotify" |
|
|
1812 | .PP |
|
|
1813 | When \f(CW\*(C`inotify (7)\*(C'\fR support has been compiled into libev (generally only |
|
|
1814 | available on Linux) and present at runtime, it will be used to speed up |
|
|
1815 | change detection where possible. The inotify descriptor will be created lazily |
|
|
1816 | when the first \f(CW\*(C`ev_stat\*(C'\fR watcher is being started. |
|
|
1817 | .PP |
|
|
1818 | Inotify presence does not change the semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers |
|
|
1819 | except that changes might be detected earlier, and in some cases, to avoid |
|
|
1820 | making regular \f(CW\*(C`stat\*(C'\fR calls. Even in the presence of inotify support |
|
|
1821 | there are many cases where libev has to resort to regular \f(CW\*(C`stat\*(C'\fR polling. |
|
|
1822 | .PP |
|
|
1823 | (There is no support for kqueue, as apparently it cannot be used to |
|
|
1824 | implement this functionality, due to the requirement of having a file |
|
|
1825 | descriptor open on the object at all times). |
|
|
1826 | .PP |
|
|
1827 | \fIThe special problem of stat time resolution\fR |
|
|
1828 | .IX Subsection "The special problem of stat time resolution" |
|
|
1829 | .PP |
|
|
1830 | The \f(CW\*(C`stat ()\*(C'\fR syscall only supports full-second resolution portably, and |
|
|
1831 | even on systems where the resolution is higher, many filesystems still |
|
|
1832 | only support whole seconds. |
|
|
1833 | .PP |
|
|
1834 | That means that, if the time is the only thing that changes, you can |
|
|
1835 | easily miss updates: on the first update, \f(CW\*(C`ev_stat\*(C'\fR detects a change and |
|
|
1836 | calls your callback, which does something. When there is another update |
|
|
1837 | within the same second, \f(CW\*(C`ev_stat\*(C'\fR will be unable to detect it as the stat |
|
|
1838 | data does not change. |
|
|
1839 | .PP |
|
|
1840 | The solution to this is to delay acting on a change for slightly more |
|
|
1841 | than a second (or till slightly after the next full second boundary), using |
|
|
1842 | a roughly one-second-delay \f(CW\*(C`ev_timer\*(C'\fR (e.g. \f(CW\*(C`ev_timer_set (w, 0., 1.02); |
|
|
1843 | ev_timer_again (loop, w)\*(C'\fR). |
|
|
1844 | .PP |
|
|
1845 | The \f(CW.02\fR offset is added to work around small timing inconsistencies |
|
|
1846 | of some operating systems (where the second counter of the current time |
|
|
1847 | might be be delayed. One such system is the Linux kernel, where a call to |
|
|
1848 | \&\f(CW\*(C`gettimeofday\*(C'\fR might return a timestamp with a full second later than |
|
|
1849 | a subsequent \f(CW\*(C`time\*(C'\fR call \- if the equivalent of \f(CW\*(C`time ()\*(C'\fR is used to |
|
|
1850 | update file times then there will be a small window where the kernel uses |
|
|
1851 | the previous second to update file times but libev might already execute |
|
|
1852 | the timer callback). |
|
|
1853 | .PP |
|
|
1854 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
1855 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1402 | .IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4 |
1856 | .IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4 |
1403 | .IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" |
1857 | .IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" |
1404 | .PD 0 |
1858 | .PD 0 |
1405 | .IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4 |
1859 | .IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4 |
1406 | .IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" |
1860 | .IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" |
… | |
… | |
1409 | \&\f(CW\*(C`path\*(C'\fR. The \f(CW\*(C`interval\*(C'\fR is a hint on how quickly a change is expected to |
1863 | \&\f(CW\*(C`path\*(C'\fR. The \f(CW\*(C`interval\*(C'\fR is a hint on how quickly a change is expected to |
1410 | be detected and should normally be specified as \f(CW0\fR to let libev choose |
1864 | be detected and should normally be specified as \f(CW0\fR to let libev choose |
1411 | a suitable value. The memory pointed to by \f(CW\*(C`path\*(C'\fR must point to the same |
1865 | a suitable value. The memory pointed to by \f(CW\*(C`path\*(C'\fR must point to the same |
1412 | path for as long as the watcher is active. |
1866 | path for as long as the watcher is active. |
1413 | .Sp |
1867 | .Sp |
1414 | The callback will be receive \f(CW\*(C`EV_STAT\*(C'\fR when a change was detected, |
1868 | The callback will receive \f(CW\*(C`EV_STAT\*(C'\fR when a change was detected, relative |
1415 | relative to the attributes at the time the watcher was started (or the |
1869 | to the attributes at the time the watcher was started (or the last change |
1416 | last change was detected). |
1870 | was detected). |
1417 | .IP "ev_stat_stat (ev_stat *)" 4 |
1871 | .IP "ev_stat_stat (loop, ev_stat *)" 4 |
1418 | .IX Item "ev_stat_stat (ev_stat *)" |
1872 | .IX Item "ev_stat_stat (loop, ev_stat *)" |
1419 | Updates the stat buffer immediately with new values. If you change the |
1873 | Updates the stat buffer immediately with new values. If you change the |
1420 | watched path in your callback, you could call this fucntion to avoid |
1874 | watched path in your callback, you could call this function to avoid |
1421 | detecting this change (while introducing a race condition). Can also be |
1875 | detecting this change (while introducing a race condition if you are not |
1422 | useful simply to find out the new values. |
1876 | the only one changing the path). Can also be useful simply to find out the |
|
|
1877 | new values. |
1423 | .IP "ev_statdata attr [read\-only]" 4 |
1878 | .IP "ev_statdata attr [read\-only]" 4 |
1424 | .IX Item "ev_statdata attr [read-only]" |
1879 | .IX Item "ev_statdata attr [read-only]" |
1425 | The most-recently detected attributes of the file. Although the type is of |
1880 | The most-recently detected attributes of the file. Although the type is |
1426 | \&\f(CW\*(C`ev_statdata\*(C'\fR, this is usually the (or one of the) \f(CW\*(C`struct stat\*(C'\fR types |
1881 | \&\f(CW\*(C`ev_statdata\*(C'\fR, this is usually the (or one of the) \f(CW\*(C`struct stat\*(C'\fR types |
|
|
1882 | suitable for your system, but you can only rely on the POSIX-standardised |
1427 | suitable for your system. If the \f(CW\*(C`st_nlink\*(C'\fR member is \f(CW0\fR, then there |
1883 | members to be present. If the \f(CW\*(C`st_nlink\*(C'\fR member is \f(CW0\fR, then there was |
1428 | was some error while \f(CW\*(C`stat\*(C'\fRing the file. |
1884 | some error while \f(CW\*(C`stat\*(C'\fRing the file. |
1429 | .IP "ev_statdata prev [read\-only]" 4 |
1885 | .IP "ev_statdata prev [read\-only]" 4 |
1430 | .IX Item "ev_statdata prev [read-only]" |
1886 | .IX Item "ev_statdata prev [read-only]" |
1431 | The previous attributes of the file. The callback gets invoked whenever |
1887 | The previous attributes of the file. The callback gets invoked whenever |
1432 | \&\f(CW\*(C`prev\*(C'\fR != \f(CW\*(C`attr\*(C'\fR. |
1888 | \&\f(CW\*(C`prev\*(C'\fR != \f(CW\*(C`attr\*(C'\fR, or, more precisely, one or more of these members |
|
|
1889 | 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, |
|
|
1890 | \&\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. |
1433 | .IP "ev_tstamp interval [read\-only]" 4 |
1891 | .IP "ev_tstamp interval [read\-only]" 4 |
1434 | .IX Item "ev_tstamp interval [read-only]" |
1892 | .IX Item "ev_tstamp interval [read-only]" |
1435 | The specified interval. |
1893 | The specified interval. |
1436 | .IP "const char *path [read\-only]" 4 |
1894 | .IP "const char *path [read\-only]" 4 |
1437 | .IX Item "const char *path [read-only]" |
1895 | .IX Item "const char *path [read-only]" |
1438 | The filesystem path that is being watched. |
1896 | The filesystem path that is being watched. |
1439 | .PP |
1897 | .PP |
|
|
1898 | \fIExamples\fR |
|
|
1899 | .IX Subsection "Examples" |
|
|
1900 | .PP |
1440 | Example: Watch \f(CW\*(C`/etc/passwd\*(C'\fR for attribute changes. |
1901 | Example: Watch \f(CW\*(C`/etc/passwd\*(C'\fR for attribute changes. |
1441 | .PP |
1902 | .PP |
1442 | .Vb 15 |
1903 | .Vb 10 |
1443 | \& static void |
1904 | \& static void |
1444 | \& passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
1905 | \& passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
1445 | \& { |
1906 | \& { |
1446 | \& /* /etc/passwd changed in some way */ |
1907 | \& /* /etc/passwd changed in some way */ |
1447 | \& if (w->attr.st_nlink) |
1908 | \& if (w\->attr.st_nlink) |
1448 | \& { |
1909 | \& { |
1449 | \& printf ("passwd current size %ld\en", (long)w->attr.st_size); |
1910 | \& printf ("passwd current size %ld\en", (long)w\->attr.st_size); |
1450 | \& printf ("passwd current atime %ld\en", (long)w->attr.st_mtime); |
1911 | \& printf ("passwd current atime %ld\en", (long)w\->attr.st_mtime); |
1451 | \& printf ("passwd current mtime %ld\en", (long)w->attr.st_mtime); |
1912 | \& printf ("passwd current mtime %ld\en", (long)w\->attr.st_mtime); |
1452 | \& } |
1913 | \& } |
1453 | \& else |
1914 | \& else |
1454 | \& /* you shalt not abuse printf for puts */ |
1915 | \& /* you shalt not abuse printf for puts */ |
1455 | \& puts ("wow, /etc/passwd is not there, expect problems. " |
1916 | \& puts ("wow, /etc/passwd is not there, expect problems. " |
1456 | \& "if this is windows, they already arrived\en"); |
1917 | \& "if this is windows, they already arrived\en"); |
1457 | \& } |
1918 | \& } |
1458 | .Ve |
1919 | \& |
1459 | .PP |
|
|
1460 | .Vb 2 |
|
|
1461 | \& ... |
1920 | \& ... |
1462 | \& ev_stat passwd; |
1921 | \& ev_stat passwd; |
|
|
1922 | \& |
|
|
1923 | \& ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.); |
|
|
1924 | \& ev_stat_start (loop, &passwd); |
1463 | .Ve |
1925 | .Ve |
|
|
1926 | .PP |
|
|
1927 | Example: Like above, but additionally use a one-second delay so we do not |
|
|
1928 | miss updates (however, frequent updates will delay processing, too, so |
|
|
1929 | one might do the work both on \f(CW\*(C`ev_stat\*(C'\fR callback invocation \fIand\fR on |
|
|
1930 | \&\f(CW\*(C`ev_timer\*(C'\fR callback invocation). |
1464 | .PP |
1931 | .PP |
1465 | .Vb 2 |
1932 | .Vb 2 |
|
|
1933 | \& static ev_stat passwd; |
|
|
1934 | \& static ev_timer timer; |
|
|
1935 | \& |
|
|
1936 | \& static void |
|
|
1937 | \& timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1938 | \& { |
|
|
1939 | \& ev_timer_stop (EV_A_ w); |
|
|
1940 | \& |
|
|
1941 | \& /* now it\*(Aqs one second after the most recent passwd change */ |
|
|
1942 | \& } |
|
|
1943 | \& |
|
|
1944 | \& static void |
|
|
1945 | \& stat_cb (EV_P_ ev_stat *w, int revents) |
|
|
1946 | \& { |
|
|
1947 | \& /* reset the one\-second timer */ |
|
|
1948 | \& ev_timer_again (EV_A_ &timer); |
|
|
1949 | \& } |
|
|
1950 | \& |
|
|
1951 | \& ... |
1466 | \& ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
1952 | \& ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
1467 | \& ev_stat_start (loop, &passwd); |
1953 | \& ev_stat_start (loop, &passwd); |
|
|
1954 | \& ev_timer_init (&timer, timer_cb, 0., 1.02); |
1468 | .Ve |
1955 | .Ve |
1469 | .ie n .Sh """ev_idle"" \- when you've got nothing better to do..." |
1956 | .ie n .Sh """ev_idle"" \- when you've got nothing better to do..." |
1470 | .el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..." |
1957 | .el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..." |
1471 | .IX Subsection "ev_idle - when you've got nothing better to do..." |
1958 | .IX Subsection "ev_idle - when you've got nothing better to do..." |
1472 | Idle watchers trigger events when there are no other events are pending |
1959 | Idle watchers trigger events when no other events of the same or higher |
1473 | (prepare, check and other idle watchers do not count). That is, as long |
1960 | priority are pending (prepare, check and other idle watchers do not |
1474 | as your process is busy handling sockets or timeouts (or even signals, |
1961 | count). |
1475 | imagine) it will not be triggered. But when your process is idle all idle |
1962 | .PP |
1476 | watchers are being called again and again, once per event loop iteration \- |
1963 | That is, as long as your process is busy handling sockets or timeouts |
|
|
1964 | (or even signals, imagine) of the same or higher priority it will not be |
|
|
1965 | triggered. But when your process is idle (or only lower-priority watchers |
|
|
1966 | are pending), the idle watchers are being called once per event loop |
1477 | until stopped, that is, or your process receives more events and becomes |
1967 | iteration \- until stopped, that is, or your process receives more events |
1478 | busy. |
1968 | and becomes busy again with higher priority stuff. |
1479 | .PP |
1969 | .PP |
1480 | The most noteworthy effect is that as long as any idle watchers are |
1970 | The most noteworthy effect is that as long as any idle watchers are |
1481 | active, the process will not block when waiting for new events. |
1971 | active, the process will not block when waiting for new events. |
1482 | .PP |
1972 | .PP |
1483 | Apart from keeping your process non-blocking (which is a useful |
1973 | Apart from keeping your process non-blocking (which is a useful |
1484 | effect on its own sometimes), idle watchers are a good place to do |
1974 | effect on its own sometimes), idle watchers are a good place to do |
1485 | \&\*(L"pseudo\-background processing\*(R", or delay processing stuff to after the |
1975 | \&\*(L"pseudo-background processing\*(R", or delay processing stuff to after the |
1486 | event loop has handled all outstanding events. |
1976 | event loop has handled all outstanding events. |
|
|
1977 | .PP |
|
|
1978 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
1979 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1487 | .IP "ev_idle_init (ev_signal *, callback)" 4 |
1980 | .IP "ev_idle_init (ev_signal *, callback)" 4 |
1488 | .IX Item "ev_idle_init (ev_signal *, callback)" |
1981 | .IX Item "ev_idle_init (ev_signal *, callback)" |
1489 | Initialises and configures the idle watcher \- it has no parameters of any |
1982 | Initialises and configures the idle watcher \- it has no parameters of any |
1490 | kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, |
1983 | kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, |
1491 | believe me. |
1984 | believe me. |
|
|
1985 | .PP |
|
|
1986 | \fIExamples\fR |
|
|
1987 | .IX Subsection "Examples" |
1492 | .PP |
1988 | .PP |
1493 | Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the |
1989 | Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the |
1494 | callback, free it. Also, use no error checking, as usual. |
1990 | callback, free it. Also, use no error checking, as usual. |
1495 | .PP |
1991 | .PP |
1496 | .Vb 7 |
1992 | .Vb 7 |
1497 | \& static void |
1993 | \& static void |
1498 | \& idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1994 | \& idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1499 | \& { |
1995 | \& { |
1500 | \& free (w); |
1996 | \& free (w); |
1501 | \& // now do something you wanted to do when the program has |
1997 | \& // now do something you wanted to do when the program has |
1502 | \& // no longer asnything immediate to do. |
1998 | \& // no longer anything immediate to do. |
1503 | \& } |
1999 | \& } |
1504 | .Ve |
2000 | \& |
1505 | .PP |
|
|
1506 | .Vb 3 |
|
|
1507 | \& struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
2001 | \& struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1508 | \& ev_idle_init (idle_watcher, idle_cb); |
2002 | \& ev_idle_init (idle_watcher, idle_cb); |
1509 | \& ev_idle_start (loop, idle_cb); |
2003 | \& ev_idle_start (loop, idle_cb); |
1510 | .Ve |
2004 | .Ve |
1511 | .ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop!" |
2005 | .ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop!" |
… | |
… | |
1546 | are ready to run (it's actually more complicated: it only runs coroutines |
2040 | are ready to run (it's actually more complicated: it only runs coroutines |
1547 | with priority higher than or equal to the event loop and one coroutine |
2041 | with priority higher than or equal to the event loop and one coroutine |
1548 | of lower priority, but only once, using idle watchers to keep the event |
2042 | of lower priority, but only once, using idle watchers to keep the event |
1549 | loop from blocking if lower-priority coroutines are active, thus mapping |
2043 | loop from blocking if lower-priority coroutines are active, thus mapping |
1550 | low-priority coroutines to idle/background tasks). |
2044 | low-priority coroutines to idle/background tasks). |
|
|
2045 | .PP |
|
|
2046 | It is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR) |
|
|
2047 | priority, to ensure that they are being run before any other watchers |
|
|
2048 | after the poll. Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers, |
|
|
2049 | too) should not activate (\*(L"feed\*(R") events into libev. While libev fully |
|
|
2050 | supports this, they might get executed before other \f(CW\*(C`ev_check\*(C'\fR watchers |
|
|
2051 | did their job. As \f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other |
|
|
2052 | (non-libev) event loops those other event loops might be in an unusable |
|
|
2053 | state until their \f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to |
|
|
2054 | coexist peacefully with others). |
|
|
2055 | .PP |
|
|
2056 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
2057 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1551 | .IP "ev_prepare_init (ev_prepare *, callback)" 4 |
2058 | .IP "ev_prepare_init (ev_prepare *, callback)" 4 |
1552 | .IX Item "ev_prepare_init (ev_prepare *, callback)" |
2059 | .IX Item "ev_prepare_init (ev_prepare *, callback)" |
1553 | .PD 0 |
2060 | .PD 0 |
1554 | .IP "ev_check_init (ev_check *, callback)" 4 |
2061 | .IP "ev_check_init (ev_check *, callback)" 4 |
1555 | .IX Item "ev_check_init (ev_check *, callback)" |
2062 | .IX Item "ev_check_init (ev_check *, callback)" |
1556 | .PD |
2063 | .PD |
1557 | Initialises and configures the prepare or check watcher \- they have no |
2064 | Initialises and configures the prepare or check watcher \- they have no |
1558 | parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR |
2065 | parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR |
1559 | macros, but using them is utterly, utterly and completely pointless. |
2066 | macros, but using them is utterly, utterly and completely pointless. |
1560 | .PP |
2067 | .PP |
1561 | Example: To include a library such as adns, you would add \s-1IO\s0 watchers |
2068 | \fIExamples\fR |
1562 | and a timeout watcher in a prepare handler, as required by libadns, and |
2069 | .IX Subsection "Examples" |
|
|
2070 | .PP |
|
|
2071 | There are a number of principal ways to embed other event loops or modules |
|
|
2072 | into libev. Here are some ideas on how to include libadns into libev |
|
|
2073 | (there is a Perl module named \f(CW\*(C`EV::ADNS\*(C'\fR that does this, which you could |
|
|
2074 | use as a working example. Another Perl module named \f(CW\*(C`EV::Glib\*(C'\fR embeds a |
|
|
2075 | Glib main context into libev, and finally, \f(CW\*(C`Glib::EV\*(C'\fR embeds \s-1EV\s0 into the |
|
|
2076 | Glib event loop). |
|
|
2077 | .PP |
|
|
2078 | Method 1: Add \s-1IO\s0 watchers and a timeout watcher in a prepare handler, |
1563 | in a check watcher, destroy them and call into libadns. What follows is |
2079 | and in a check watcher, destroy them and call into libadns. What follows |
1564 | pseudo-code only of course: |
2080 | is pseudo-code only of course. This requires you to either use a low |
|
|
2081 | priority for the check watcher or use \f(CW\*(C`ev_clear_pending\*(C'\fR explicitly, as |
|
|
2082 | the callbacks for the IO/timeout watchers might not have been called yet. |
1565 | .PP |
2083 | .PP |
1566 | .Vb 2 |
2084 | .Vb 2 |
1567 | \& static ev_io iow [nfd]; |
2085 | \& static ev_io iow [nfd]; |
1568 | \& static ev_timer tw; |
2086 | \& static ev_timer tw; |
1569 | .Ve |
2087 | \& |
1570 | .PP |
|
|
1571 | .Vb 9 |
|
|
1572 | \& static void |
2088 | \& static void |
1573 | \& io_cb (ev_loop *loop, ev_io *w, int revents) |
2089 | \& io_cb (ev_loop *loop, ev_io *w, int revents) |
1574 | \& { |
2090 | \& { |
1575 | \& // set the relevant poll flags |
|
|
1576 | \& // could also call adns_processreadable etc. here |
|
|
1577 | \& struct pollfd *fd = (struct pollfd *)w->data; |
|
|
1578 | \& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1579 | \& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1580 | \& } |
2091 | \& } |
1581 | .Ve |
2092 | \& |
1582 | .PP |
|
|
1583 | .Vb 7 |
|
|
1584 | \& // create io watchers for each fd and a timer before blocking |
2093 | \& // create io watchers for each fd and a timer before blocking |
1585 | \& static void |
2094 | \& static void |
1586 | \& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
2095 | \& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1587 | \& { |
2096 | \& { |
1588 | \& int timeout = 3600000;truct pollfd fds [nfd]; |
2097 | \& int timeout = 3600000; |
|
|
2098 | \& struct pollfd fds [nfd]; |
1589 | \& // actual code will need to loop here and realloc etc. |
2099 | \& // actual code will need to loop here and realloc etc. |
1590 | \& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
2100 | \& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1591 | .Ve |
2101 | \& |
1592 | .PP |
|
|
1593 | .Vb 3 |
|
|
1594 | \& /* the callback is illegal, but won't be called as we stop during check */ |
2102 | \& /* the callback is illegal, but won\*(Aqt be called as we stop during check */ |
1595 | \& ev_timer_init (&tw, 0, timeout * 1e-3); |
2103 | \& ev_timer_init (&tw, 0, timeout * 1e\-3); |
1596 | \& ev_timer_start (loop, &tw); |
2104 | \& ev_timer_start (loop, &tw); |
1597 | .Ve |
2105 | \& |
1598 | .PP |
|
|
1599 | .Vb 6 |
|
|
1600 | \& // create on ev_io per pollfd |
2106 | \& // create one ev_io per pollfd |
1601 | \& for (int i = 0; i < nfd; ++i) |
2107 | \& for (int i = 0; i < nfd; ++i) |
1602 | \& { |
2108 | \& { |
1603 | \& ev_io_init (iow + i, io_cb, fds [i].fd, |
2109 | \& ev_io_init (iow + i, io_cb, fds [i].fd, |
1604 | \& ((fds [i].events & POLLIN ? EV_READ : 0) |
2110 | \& ((fds [i].events & POLLIN ? EV_READ : 0) |
1605 | \& | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
2111 | \& | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1606 | .Ve |
2112 | \& |
1607 | .PP |
|
|
1608 | .Vb 5 |
|
|
1609 | \& fds [i].revents = 0; |
2113 | \& fds [i].revents = 0; |
1610 | \& iow [i].data = fds + i; |
|
|
1611 | \& ev_io_start (loop, iow + i); |
2114 | \& ev_io_start (loop, iow + i); |
1612 | \& } |
2115 | \& } |
1613 | \& } |
2116 | \& } |
1614 | .Ve |
2117 | \& |
1615 | .PP |
|
|
1616 | .Vb 5 |
|
|
1617 | \& // stop all watchers after blocking |
2118 | \& // stop all watchers after blocking |
1618 | \& static void |
2119 | \& static void |
1619 | \& adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
2120 | \& adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1620 | \& { |
2121 | \& { |
1621 | \& ev_timer_stop (loop, &tw); |
2122 | \& ev_timer_stop (loop, &tw); |
1622 | .Ve |
2123 | \& |
1623 | .PP |
|
|
1624 | .Vb 2 |
|
|
1625 | \& for (int i = 0; i < nfd; ++i) |
2124 | \& for (int i = 0; i < nfd; ++i) |
|
|
2125 | \& { |
|
|
2126 | \& // set the relevant poll flags |
|
|
2127 | \& // could also call adns_processreadable etc. here |
|
|
2128 | \& struct pollfd *fd = fds + i; |
|
|
2129 | \& int revents = ev_clear_pending (iow + i); |
|
|
2130 | \& if (revents & EV_READ ) fd\->revents |= fd\->events & POLLIN; |
|
|
2131 | \& if (revents & EV_WRITE) fd\->revents |= fd\->events & POLLOUT; |
|
|
2132 | \& |
|
|
2133 | \& // now stop the watcher |
1626 | \& ev_io_stop (loop, iow + i); |
2134 | \& ev_io_stop (loop, iow + i); |
1627 | .Ve |
2135 | \& } |
1628 | .PP |
2136 | \& |
1629 | .Vb 2 |
|
|
1630 | \& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
2137 | \& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
2138 | \& } |
|
|
2139 | .Ve |
|
|
2140 | .PP |
|
|
2141 | Method 2: This would be just like method 1, but you run \f(CW\*(C`adns_afterpoll\*(C'\fR |
|
|
2142 | in the prepare watcher and would dispose of the check watcher. |
|
|
2143 | .PP |
|
|
2144 | Method 3: If the module to be embedded supports explicit event |
|
|
2145 | notification (adns does), you can also make use of the actual watcher |
|
|
2146 | callbacks, and only destroy/create the watchers in the prepare watcher. |
|
|
2147 | .PP |
|
|
2148 | .Vb 5 |
|
|
2149 | \& static void |
|
|
2150 | \& timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
2151 | \& { |
|
|
2152 | \& adns_state ads = (adns_state)w\->data; |
|
|
2153 | \& update_now (EV_A); |
|
|
2154 | \& |
|
|
2155 | \& adns_processtimeouts (ads, &tv_now); |
|
|
2156 | \& } |
|
|
2157 | \& |
|
|
2158 | \& static void |
|
|
2159 | \& io_cb (EV_P_ ev_io *w, int revents) |
|
|
2160 | \& { |
|
|
2161 | \& adns_state ads = (adns_state)w\->data; |
|
|
2162 | \& update_now (EV_A); |
|
|
2163 | \& |
|
|
2164 | \& if (revents & EV_READ ) adns_processreadable (ads, w\->fd, &tv_now); |
|
|
2165 | \& if (revents & EV_WRITE) adns_processwriteable (ads, w\->fd, &tv_now); |
|
|
2166 | \& } |
|
|
2167 | \& |
|
|
2168 | \& // do not ever call adns_afterpoll |
|
|
2169 | .Ve |
|
|
2170 | .PP |
|
|
2171 | Method 4: Do not use a prepare or check watcher because the module you |
|
|
2172 | want to embed is too inflexible to support it. Instead, youc na override |
|
|
2173 | their poll function. The drawback with this solution is that the main |
|
|
2174 | loop is now no longer controllable by \s-1EV\s0. The \f(CW\*(C`Glib::EV\*(C'\fR module does |
|
|
2175 | this. |
|
|
2176 | .PP |
|
|
2177 | .Vb 4 |
|
|
2178 | \& static gint |
|
|
2179 | \& event_poll_func (GPollFD *fds, guint nfds, gint timeout) |
|
|
2180 | \& { |
|
|
2181 | \& int got_events = 0; |
|
|
2182 | \& |
|
|
2183 | \& for (n = 0; n < nfds; ++n) |
|
|
2184 | \& // create/start io watcher that sets the relevant bits in fds[n] and increment got_events |
|
|
2185 | \& |
|
|
2186 | \& if (timeout >= 0) |
|
|
2187 | \& // create/start timer |
|
|
2188 | \& |
|
|
2189 | \& // poll |
|
|
2190 | \& ev_loop (EV_A_ 0); |
|
|
2191 | \& |
|
|
2192 | \& // stop timer again |
|
|
2193 | \& if (timeout >= 0) |
|
|
2194 | \& ev_timer_stop (EV_A_ &to); |
|
|
2195 | \& |
|
|
2196 | \& // stop io watchers again \- their callbacks should have set |
|
|
2197 | \& for (n = 0; n < nfds; ++n) |
|
|
2198 | \& ev_io_stop (EV_A_ iow [n]); |
|
|
2199 | \& |
|
|
2200 | \& return got_events; |
1631 | \& } |
2201 | \& } |
1632 | .Ve |
2202 | .Ve |
1633 | .ie n .Sh """ev_embed"" \- when one backend isn't enough..." |
2203 | .ie n .Sh """ev_embed"" \- when one backend isn't enough..." |
1634 | .el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..." |
2204 | .el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..." |
1635 | .IX Subsection "ev_embed - when one backend isn't enough..." |
2205 | .IX Subsection "ev_embed - when one backend isn't enough..." |
… | |
… | |
1678 | portable one. |
2248 | portable one. |
1679 | .PP |
2249 | .PP |
1680 | So when you want to use this feature you will always have to be prepared |
2250 | So when you want to use this feature you will always have to be prepared |
1681 | that you cannot get an embeddable loop. The recommended way to get around |
2251 | that you cannot get an embeddable loop. The recommended way to get around |
1682 | this is to have a separate variables for your embeddable loop, try to |
2252 | this is to have a separate variables for your embeddable loop, try to |
1683 | create it, and if that fails, use the normal loop for everything: |
2253 | create it, and if that fails, use the normal loop for everything. |
1684 | .PP |
2254 | .PP |
1685 | .Vb 3 |
2255 | \fIWatcher-Specific Functions and Data Members\fR |
1686 | \& struct ev_loop *loop_hi = ev_default_init (0); |
2256 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1687 | \& struct ev_loop *loop_lo = 0; |
|
|
1688 | \& struct ev_embed embed; |
|
|
1689 | .Ve |
|
|
1690 | .PP |
|
|
1691 | .Vb 5 |
|
|
1692 | \& // see if there is a chance of getting one that works |
|
|
1693 | \& // (remember that a flags value of 0 means autodetection) |
|
|
1694 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
|
|
1695 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
|
|
1696 | \& : 0; |
|
|
1697 | .Ve |
|
|
1698 | .PP |
|
|
1699 | .Vb 8 |
|
|
1700 | \& // if we got one, then embed it, otherwise default to loop_hi |
|
|
1701 | \& if (loop_lo) |
|
|
1702 | \& { |
|
|
1703 | \& ev_embed_init (&embed, 0, loop_lo); |
|
|
1704 | \& ev_embed_start (loop_hi, &embed); |
|
|
1705 | \& } |
|
|
1706 | \& else |
|
|
1707 | \& loop_lo = loop_hi; |
|
|
1708 | .Ve |
|
|
1709 | .IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
2257 | .IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
1710 | .IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" |
2258 | .IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" |
1711 | .PD 0 |
2259 | .PD 0 |
1712 | .IP "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
2260 | .IP "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
1713 | .IX Item "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" |
2261 | .IX Item "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" |
… | |
… | |
1720 | .IP "ev_embed_sweep (loop, ev_embed *)" 4 |
2268 | .IP "ev_embed_sweep (loop, ev_embed *)" 4 |
1721 | .IX Item "ev_embed_sweep (loop, ev_embed *)" |
2269 | .IX Item "ev_embed_sweep (loop, ev_embed *)" |
1722 | Make a single, non-blocking sweep over the embedded loop. This works |
2270 | Make a single, non-blocking sweep over the embedded loop. This works |
1723 | similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most |
2271 | similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most |
1724 | apropriate way for embedded loops. |
2272 | apropriate way for embedded loops. |
1725 | .IP "struct ev_loop *loop [read\-only]" 4 |
2273 | .IP "struct ev_loop *other [read\-only]" 4 |
1726 | .IX Item "struct ev_loop *loop [read-only]" |
2274 | .IX Item "struct ev_loop *other [read-only]" |
1727 | The embedded event loop. |
2275 | The embedded event loop. |
|
|
2276 | .PP |
|
|
2277 | \fIExamples\fR |
|
|
2278 | .IX Subsection "Examples" |
|
|
2279 | .PP |
|
|
2280 | Example: Try to get an embeddable event loop and embed it into the default |
|
|
2281 | event loop. If that is not possible, use the default loop. The default |
|
|
2282 | loop is stored in \f(CW\*(C`loop_hi\*(C'\fR, while the mebeddable loop is stored in |
|
|
2283 | \&\f(CW\*(C`loop_lo\*(C'\fR (which is \f(CW\*(C`loop_hi\*(C'\fR in the acse no embeddable loop can be |
|
|
2284 | used). |
|
|
2285 | .PP |
|
|
2286 | .Vb 3 |
|
|
2287 | \& struct ev_loop *loop_hi = ev_default_init (0); |
|
|
2288 | \& struct ev_loop *loop_lo = 0; |
|
|
2289 | \& struct ev_embed embed; |
|
|
2290 | \& |
|
|
2291 | \& // see if there is a chance of getting one that works |
|
|
2292 | \& // (remember that a flags value of 0 means autodetection) |
|
|
2293 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
|
|
2294 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
|
|
2295 | \& : 0; |
|
|
2296 | \& |
|
|
2297 | \& // if we got one, then embed it, otherwise default to loop_hi |
|
|
2298 | \& if (loop_lo) |
|
|
2299 | \& { |
|
|
2300 | \& ev_embed_init (&embed, 0, loop_lo); |
|
|
2301 | \& ev_embed_start (loop_hi, &embed); |
|
|
2302 | \& } |
|
|
2303 | \& else |
|
|
2304 | \& loop_lo = loop_hi; |
|
|
2305 | .Ve |
|
|
2306 | .PP |
|
|
2307 | Example: Check if kqueue is available but not recommended and create |
|
|
2308 | a kqueue backend for use with sockets (which usually work with any |
|
|
2309 | kqueue implementation). Store the kqueue/socket\-only event loop in |
|
|
2310 | \&\f(CW\*(C`loop_socket\*(C'\fR. (One might optionally use \f(CW\*(C`EVFLAG_NOENV\*(C'\fR, too). |
|
|
2311 | .PP |
|
|
2312 | .Vb 3 |
|
|
2313 | \& struct ev_loop *loop = ev_default_init (0); |
|
|
2314 | \& struct ev_loop *loop_socket = 0; |
|
|
2315 | \& struct ev_embed embed; |
|
|
2316 | \& |
|
|
2317 | \& if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
|
|
2318 | \& if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
|
|
2319 | \& { |
|
|
2320 | \& ev_embed_init (&embed, 0, loop_socket); |
|
|
2321 | \& ev_embed_start (loop, &embed); |
|
|
2322 | \& } |
|
|
2323 | \& |
|
|
2324 | \& if (!loop_socket) |
|
|
2325 | \& loop_socket = loop; |
|
|
2326 | \& |
|
|
2327 | \& // now use loop_socket for all sockets, and loop for everything else |
|
|
2328 | .Ve |
1728 | .ie n .Sh """ev_fork"" \- the audacity to resume the event loop after a fork" |
2329 | .ie n .Sh """ev_fork"" \- the audacity to resume the event loop after a fork" |
1729 | .el .Sh "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
2330 | .el .Sh "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
1730 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
2331 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
1731 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
2332 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
1732 | whoever is a good citizen cared to tell libev about it by calling |
2333 | whoever is a good citizen cared to tell libev about it by calling |
1733 | \&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the |
2334 | \&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the |
1734 | event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, |
2335 | event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, |
1735 | and only in the child after the fork. If whoever good citizen calling |
2336 | and only in the child after the fork. If whoever good citizen calling |
1736 | \&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork |
2337 | \&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork |
1737 | handlers will be invoked, too, of course. |
2338 | handlers will be invoked, too, of course. |
|
|
2339 | .PP |
|
|
2340 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
2341 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1738 | .IP "ev_fork_init (ev_signal *, callback)" 4 |
2342 | .IP "ev_fork_init (ev_signal *, callback)" 4 |
1739 | .IX Item "ev_fork_init (ev_signal *, callback)" |
2343 | .IX Item "ev_fork_init (ev_signal *, callback)" |
1740 | Initialises and configures the fork watcher \- it has no parameters of any |
2344 | Initialises and configures the fork watcher \- it has no parameters of any |
1741 | kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless, |
2345 | kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless, |
1742 | believe me. |
2346 | believe me. |
|
|
2347 | .ie n .Sh """ev_async"" \- how to wake up another event loop" |
|
|
2348 | .el .Sh "\f(CWev_async\fP \- how to wake up another event loop" |
|
|
2349 | .IX Subsection "ev_async - how to wake up another event loop" |
|
|
2350 | In general, you cannot use an \f(CW\*(C`ev_loop\*(C'\fR from multiple threads or other |
|
|
2351 | asynchronous sources such as signal handlers (as opposed to multiple event |
|
|
2352 | loops \- those are of course safe to use in different threads). |
|
|
2353 | .PP |
|
|
2354 | Sometimes, however, you need to wake up another event loop you do not |
|
|
2355 | control, for example because it belongs to another thread. This is what |
|
|
2356 | \&\f(CW\*(C`ev_async\*(C'\fR watchers do: as long as the \f(CW\*(C`ev_async\*(C'\fR watcher is active, you |
|
|
2357 | can signal it by calling \f(CW\*(C`ev_async_send\*(C'\fR, which is thread\- and signal |
|
|
2358 | safe. |
|
|
2359 | .PP |
|
|
2360 | This functionality is very similar to \f(CW\*(C`ev_signal\*(C'\fR watchers, as signals, |
|
|
2361 | too, are asynchronous in nature, and signals, too, will be compressed |
|
|
2362 | (i.e. the number of callback invocations may be less than the number of |
|
|
2363 | \&\f(CW\*(C`ev_async_sent\*(C'\fR calls). |
|
|
2364 | .PP |
|
|
2365 | Unlike \f(CW\*(C`ev_signal\*(C'\fR watchers, \f(CW\*(C`ev_async\*(C'\fR works with any event loop, not |
|
|
2366 | just the default loop. |
|
|
2367 | .PP |
|
|
2368 | \fIQueueing\fR |
|
|
2369 | .IX Subsection "Queueing" |
|
|
2370 | .PP |
|
|
2371 | \&\f(CW\*(C`ev_async\*(C'\fR does not support queueing of data in any way. The reason |
|
|
2372 | is that the author does not know of a simple (or any) algorithm for a |
|
|
2373 | multiple-writer-single-reader queue that works in all cases and doesn't |
|
|
2374 | need elaborate support such as pthreads. |
|
|
2375 | .PP |
|
|
2376 | That means that if you want to queue data, you have to provide your own |
|
|
2377 | queue. But at least I can tell you would implement locking around your |
|
|
2378 | queue: |
|
|
2379 | .IP "queueing from a signal handler context" 4 |
|
|
2380 | .IX Item "queueing from a signal handler context" |
|
|
2381 | To implement race-free queueing, you simply add to the queue in the signal |
|
|
2382 | handler but you block the signal handler in the watcher callback. Here is an example that does that for |
|
|
2383 | some fictitiuous \s-1SIGUSR1\s0 handler: |
|
|
2384 | .Sp |
|
|
2385 | .Vb 1 |
|
|
2386 | \& static ev_async mysig; |
|
|
2387 | \& |
|
|
2388 | \& static void |
|
|
2389 | \& sigusr1_handler (void) |
|
|
2390 | \& { |
|
|
2391 | \& sometype data; |
|
|
2392 | \& |
|
|
2393 | \& // no locking etc. |
|
|
2394 | \& queue_put (data); |
|
|
2395 | \& ev_async_send (EV_DEFAULT_ &mysig); |
|
|
2396 | \& } |
|
|
2397 | \& |
|
|
2398 | \& static void |
|
|
2399 | \& mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
2400 | \& { |
|
|
2401 | \& sometype data; |
|
|
2402 | \& sigset_t block, prev; |
|
|
2403 | \& |
|
|
2404 | \& sigemptyset (&block); |
|
|
2405 | \& sigaddset (&block, SIGUSR1); |
|
|
2406 | \& sigprocmask (SIG_BLOCK, &block, &prev); |
|
|
2407 | \& |
|
|
2408 | \& while (queue_get (&data)) |
|
|
2409 | \& process (data); |
|
|
2410 | \& |
|
|
2411 | \& if (sigismember (&prev, SIGUSR1) |
|
|
2412 | \& sigprocmask (SIG_UNBLOCK, &block, 0); |
|
|
2413 | \& } |
|
|
2414 | .Ve |
|
|
2415 | .Sp |
|
|
2416 | (Note: pthreads in theory requires you to use \f(CW\*(C`pthread_setmask\*(C'\fR |
|
|
2417 | instead of \f(CW\*(C`sigprocmask\*(C'\fR when you use threads, but libev doesn't do it |
|
|
2418 | either...). |
|
|
2419 | .IP "queueing from a thread context" 4 |
|
|
2420 | .IX Item "queueing from a thread context" |
|
|
2421 | The strategy for threads is different, as you cannot (easily) block |
|
|
2422 | threads but you can easily preempt them, so to queue safely you need to |
|
|
2423 | employ a traditional mutex lock, such as in this pthread example: |
|
|
2424 | .Sp |
|
|
2425 | .Vb 2 |
|
|
2426 | \& static ev_async mysig; |
|
|
2427 | \& static pthread_mutex_t mymutex = PTHREAD_MUTEX_INITIALIZER; |
|
|
2428 | \& |
|
|
2429 | \& static void |
|
|
2430 | \& otherthread (void) |
|
|
2431 | \& { |
|
|
2432 | \& // only need to lock the actual queueing operation |
|
|
2433 | \& pthread_mutex_lock (&mymutex); |
|
|
2434 | \& queue_put (data); |
|
|
2435 | \& pthread_mutex_unlock (&mymutex); |
|
|
2436 | \& |
|
|
2437 | \& ev_async_send (EV_DEFAULT_ &mysig); |
|
|
2438 | \& } |
|
|
2439 | \& |
|
|
2440 | \& static void |
|
|
2441 | \& mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
2442 | \& { |
|
|
2443 | \& pthread_mutex_lock (&mymutex); |
|
|
2444 | \& |
|
|
2445 | \& while (queue_get (&data)) |
|
|
2446 | \& process (data); |
|
|
2447 | \& |
|
|
2448 | \& pthread_mutex_unlock (&mymutex); |
|
|
2449 | \& } |
|
|
2450 | .Ve |
|
|
2451 | .PP |
|
|
2452 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
2453 | .IX Subsection "Watcher-Specific Functions and Data Members" |
|
|
2454 | .IP "ev_async_init (ev_async *, callback)" 4 |
|
|
2455 | .IX Item "ev_async_init (ev_async *, callback)" |
|
|
2456 | Initialises and configures the async watcher \- it has no parameters of any |
|
|
2457 | kind. There is a \f(CW\*(C`ev_asynd_set\*(C'\fR macro, but using it is utterly pointless, |
|
|
2458 | believe me. |
|
|
2459 | .IP "ev_async_send (loop, ev_async *)" 4 |
|
|
2460 | .IX Item "ev_async_send (loop, ev_async *)" |
|
|
2461 | Sends/signals/activates the given \f(CW\*(C`ev_async\*(C'\fR watcher, that is, feeds |
|
|
2462 | an \f(CW\*(C`EV_ASYNC\*(C'\fR event on the watcher into the event loop. Unlike |
|
|
2463 | \&\f(CW\*(C`ev_feed_event\*(C'\fR, this call is safe to do in other threads, signal or |
|
|
2464 | similar contexts (see the dicusssion of \f(CW\*(C`EV_ATOMIC_T\*(C'\fR in the embedding |
|
|
2465 | section below on what exactly this means). |
|
|
2466 | .Sp |
|
|
2467 | This call incurs the overhead of a syscall only once per loop iteration, |
|
|
2468 | so while the overhead might be noticable, it doesn't apply to repeated |
|
|
2469 | calls to \f(CW\*(C`ev_async_send\*(C'\fR. |
|
|
2470 | .IP "bool = ev_async_pending (ev_async *)" 4 |
|
|
2471 | .IX Item "bool = ev_async_pending (ev_async *)" |
|
|
2472 | Returns a non-zero value when \f(CW\*(C`ev_async_send\*(C'\fR has been called on the |
|
|
2473 | watcher but the event has not yet been processed (or even noted) by the |
|
|
2474 | event loop. |
|
|
2475 | .Sp |
|
|
2476 | \&\f(CW\*(C`ev_async_send\*(C'\fR sets a flag in the watcher and wakes up the loop. When |
|
|
2477 | the loop iterates next and checks for the watcher to have become active, |
|
|
2478 | it will reset the flag again. \f(CW\*(C`ev_async_pending\*(C'\fR can be used to very |
|
|
2479 | quickly check wether invoking the loop might be a good idea. |
|
|
2480 | .Sp |
|
|
2481 | Not that this does \fInot\fR check wether the watcher itself is pending, only |
|
|
2482 | wether it has been requested to make this watcher pending. |
1743 | .SH "OTHER FUNCTIONS" |
2483 | .SH "OTHER FUNCTIONS" |
1744 | .IX Header "OTHER FUNCTIONS" |
2484 | .IX Header "OTHER FUNCTIONS" |
1745 | There are some other functions of possible interest. Described. Here. Now. |
2485 | There are some other functions of possible interest. Described. Here. Now. |
1746 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 |
2486 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 |
1747 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" |
2487 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" |
… | |
… | |
1771 | \& if (revents & EV_TIMEOUT) |
2511 | \& if (revents & EV_TIMEOUT) |
1772 | \& /* doh, nothing entered */; |
2512 | \& /* doh, nothing entered */; |
1773 | \& else if (revents & EV_READ) |
2513 | \& else if (revents & EV_READ) |
1774 | \& /* stdin might have data for us, joy! */; |
2514 | \& /* stdin might have data for us, joy! */; |
1775 | \& } |
2515 | \& } |
1776 | .Ve |
2516 | \& |
1777 | .Sp |
|
|
1778 | .Vb 1 |
|
|
1779 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
2517 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
1780 | .Ve |
2518 | .Ve |
1781 | .IP "ev_feed_event (ev_loop *, watcher *, int revents)" 4 |
2519 | .IP "ev_feed_event (ev_loop *, watcher *, int revents)" 4 |
1782 | .IX Item "ev_feed_event (ev_loop *, watcher *, int revents)" |
2520 | .IX Item "ev_feed_event (ev_loop *, watcher *, int revents)" |
1783 | Feeds the given event set into the event loop, as if the specified event |
2521 | Feeds the given event set into the event loop, as if the specified event |
… | |
… | |
1793 | loop!). |
2531 | loop!). |
1794 | .SH "LIBEVENT EMULATION" |
2532 | .SH "LIBEVENT EMULATION" |
1795 | .IX Header "LIBEVENT EMULATION" |
2533 | .IX Header "LIBEVENT EMULATION" |
1796 | Libev offers a compatibility emulation layer for libevent. It cannot |
2534 | Libev offers a compatibility emulation layer for libevent. It cannot |
1797 | emulate the internals of libevent, so here are some usage hints: |
2535 | emulate the internals of libevent, so here are some usage hints: |
|
|
2536 | .IP "\(bu" 4 |
1798 | .IP "* Use it by including <event.h>, as usual." 4 |
2537 | Use it by including <event.h>, as usual. |
1799 | .IX Item "Use it by including <event.h>, as usual." |
2538 | .IP "\(bu" 4 |
1800 | .PD 0 |
2539 | The following members are fully supported: ev_base, ev_callback, |
1801 | .IP "* The following members are fully supported: ev_base, ev_callback, ev_arg, ev_fd, ev_res, ev_events." 4 |
2540 | ev_arg, ev_fd, ev_res, ev_events. |
1802 | .IX Item "The following members are fully supported: ev_base, ev_callback, ev_arg, ev_fd, ev_res, ev_events." |
2541 | .IP "\(bu" 4 |
1803 | .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 |
2542 | Avoid using ev_flags and the EVLIST_*\-macros, while it is |
1804 | .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)." |
2543 | maintained by libev, it does not work exactly the same way as in libevent (consider |
1805 | .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 |
2544 | it a private \s-1API\s0). |
1806 | .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." |
2545 | .IP "\(bu" 4 |
|
|
2546 | Priorities are not currently supported. Initialising priorities |
|
|
2547 | will fail and all watchers will have the same priority, even though there |
|
|
2548 | is an ev_pri field. |
|
|
2549 | .IP "\(bu" 4 |
|
|
2550 | In libevent, the last base created gets the signals, in libev, the |
|
|
2551 | first base created (== the default loop) gets the signals. |
|
|
2552 | .IP "\(bu" 4 |
1807 | .IP "* Other members are not supported." 4 |
2553 | Other members are not supported. |
1808 | .IX Item "Other members are not supported." |
2554 | .IP "\(bu" 4 |
1809 | .IP "* The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need to use the libev header file and library." 4 |
2555 | The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need |
1810 | .IX Item "The libev emulation is not ABI compatible to libevent, you need to use the libev header file and library." |
2556 | to use the libev header file and library. |
1811 | .PD |
|
|
1812 | .SH "\*(C+ SUPPORT" |
2557 | .SH "\*(C+ SUPPORT" |
1813 | .IX Header " SUPPORT" |
2558 | .IX Header " SUPPORT" |
1814 | Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow |
2559 | Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow |
1815 | you to use some convinience methods to start/stop watchers and also change |
2560 | you to use some convinience methods to start/stop watchers and also change |
1816 | the callback model to a model using method callbacks on objects. |
2561 | the callback model to a model using method callbacks on objects. |
… | |
… | |
1819 | .PP |
2564 | .PP |
1820 | .Vb 1 |
2565 | .Vb 1 |
1821 | \& #include <ev++.h> |
2566 | \& #include <ev++.h> |
1822 | .Ve |
2567 | .Ve |
1823 | .PP |
2568 | .PP |
1824 | (it is not installed by default). This automatically includes \fIev.h\fR |
2569 | This automatically includes \fIev.h\fR and puts all of its definitions (many |
1825 | and puts all of its definitions (many of them macros) into the global |
2570 | of them macros) into the global namespace. All \*(C+ specific things are |
1826 | namespace. All \*(C+ specific things are put into the \f(CW\*(C`ev\*(C'\fR namespace. |
2571 | put into the \f(CW\*(C`ev\*(C'\fR namespace. It should support all the same embedding |
|
|
2572 | options as \fIev.h\fR, most notably \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. |
1827 | .PP |
2573 | .PP |
1828 | It should support all the same embedding options as \fIev.h\fR, most notably |
2574 | Care has been taken to keep the overhead low. The only data member the \*(C+ |
1829 | \&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. |
2575 | classes add (compared to plain C\-style watchers) is the event loop pointer |
|
|
2576 | that the watcher is associated with (or no additional members at all if |
|
|
2577 | you disable \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR when embedding libev). |
|
|
2578 | .PP |
|
|
2579 | Currently, functions, and static and non-static member functions can be |
|
|
2580 | used as callbacks. Other types should be easy to add as long as they only |
|
|
2581 | need one additional pointer for context. If you need support for other |
|
|
2582 | types of functors please contact the author (preferably after implementing |
|
|
2583 | it). |
1830 | .PP |
2584 | .PP |
1831 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
2585 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
1832 | .ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4 |
2586 | .ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4 |
1833 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
2587 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
1834 | .IX Item "ev::READ, ev::WRITE etc." |
2588 | .IX Item "ev::READ, ev::WRITE etc." |
… | |
… | |
1846 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
2600 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
1847 | defines by many implementations. |
2601 | defines by many implementations. |
1848 | .Sp |
2602 | .Sp |
1849 | All of those classes have these methods: |
2603 | All of those classes have these methods: |
1850 | .RS 4 |
2604 | .RS 4 |
1851 | .IP "ev::TYPE::TYPE (object *, object::method *)" 4 |
2605 | .IP "ev::TYPE::TYPE ()" 4 |
1852 | .IX Item "ev::TYPE::TYPE (object *, object::method *)" |
2606 | .IX Item "ev::TYPE::TYPE ()" |
1853 | .PD 0 |
2607 | .PD 0 |
1854 | .IP "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" 4 |
2608 | .IP "ev::TYPE::TYPE (struct ev_loop *)" 4 |
1855 | .IX Item "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" |
2609 | .IX Item "ev::TYPE::TYPE (struct ev_loop *)" |
1856 | .IP "ev::TYPE::~TYPE" 4 |
2610 | .IP "ev::TYPE::~TYPE" 4 |
1857 | .IX Item "ev::TYPE::~TYPE" |
2611 | .IX Item "ev::TYPE::~TYPE" |
1858 | .PD |
2612 | .PD |
1859 | The constructor takes a pointer to an object and a method pointer to |
2613 | The constructor (optionally) takes an event loop to associate the watcher |
1860 | the event handler callback to call in this class. The constructor calls |
2614 | with. If it is omitted, it will use \f(CW\*(C`EV_DEFAULT\*(C'\fR. |
1861 | \&\f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the \f(CW\*(C`set\*(C'\fR method |
2615 | .Sp |
1862 | before starting it. If you do not specify a loop then the constructor |
2616 | The constructor calls \f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the |
1863 | automatically associates the default loop with this watcher. |
2617 | \&\f(CW\*(C`set\*(C'\fR method before starting it. |
|
|
2618 | .Sp |
|
|
2619 | It will not set a callback, however: You have to call the templated \f(CW\*(C`set\*(C'\fR |
|
|
2620 | method to set a callback before you can start the watcher. |
|
|
2621 | .Sp |
|
|
2622 | (The reason why you have to use a method is a limitation in \*(C+ which does |
|
|
2623 | not allow explicit template arguments for constructors). |
1864 | .Sp |
2624 | .Sp |
1865 | The destructor automatically stops the watcher if it is active. |
2625 | The destructor automatically stops the watcher if it is active. |
|
|
2626 | .IP "w\->set<class, &class::method> (object *)" 4 |
|
|
2627 | .IX Item "w->set<class, &class::method> (object *)" |
|
|
2628 | This method sets the callback method to call. The method has to have a |
|
|
2629 | signature of \f(CW\*(C`void (*)(ev_TYPE &, int)\*(C'\fR, it receives the watcher as |
|
|
2630 | first argument and the \f(CW\*(C`revents\*(C'\fR as second. The object must be given as |
|
|
2631 | parameter and is stored in the \f(CW\*(C`data\*(C'\fR member of the watcher. |
|
|
2632 | .Sp |
|
|
2633 | This method synthesizes efficient thunking code to call your method from |
|
|
2634 | the C callback that libev requires. If your compiler can inline your |
|
|
2635 | callback (i.e. it is visible to it at the place of the \f(CW\*(C`set\*(C'\fR call and |
|
|
2636 | your compiler is good :), then the method will be fully inlined into the |
|
|
2637 | thunking function, making it as fast as a direct C callback. |
|
|
2638 | .Sp |
|
|
2639 | Example: simple class declaration and watcher initialisation |
|
|
2640 | .Sp |
|
|
2641 | .Vb 4 |
|
|
2642 | \& struct myclass |
|
|
2643 | \& { |
|
|
2644 | \& void io_cb (ev::io &w, int revents) { } |
|
|
2645 | \& } |
|
|
2646 | \& |
|
|
2647 | \& myclass obj; |
|
|
2648 | \& ev::io iow; |
|
|
2649 | \& iow.set <myclass, &myclass::io_cb> (&obj); |
|
|
2650 | .Ve |
|
|
2651 | .IP "w\->set<function> (void *data = 0)" 4 |
|
|
2652 | .IX Item "w->set<function> (void *data = 0)" |
|
|
2653 | Also sets a callback, but uses a static method or plain function as |
|
|
2654 | callback. The optional \f(CW\*(C`data\*(C'\fR argument will be stored in the watcher's |
|
|
2655 | \&\f(CW\*(C`data\*(C'\fR member and is free for you to use. |
|
|
2656 | .Sp |
|
|
2657 | The prototype of the \f(CW\*(C`function\*(C'\fR must be \f(CW\*(C`void (*)(ev::TYPE &w, int)\*(C'\fR. |
|
|
2658 | .Sp |
|
|
2659 | See the method\-\f(CW\*(C`set\*(C'\fR above for more details. |
|
|
2660 | .Sp |
|
|
2661 | Example: |
|
|
2662 | .Sp |
|
|
2663 | .Vb 2 |
|
|
2664 | \& static void io_cb (ev::io &w, int revents) { } |
|
|
2665 | \& iow.set <io_cb> (); |
|
|
2666 | .Ve |
1866 | .IP "w\->set (struct ev_loop *)" 4 |
2667 | .IP "w\->set (struct ev_loop *)" 4 |
1867 | .IX Item "w->set (struct ev_loop *)" |
2668 | .IX Item "w->set (struct ev_loop *)" |
1868 | Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only |
2669 | Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only |
1869 | do this when the watcher is inactive (and not pending either). |
2670 | do this when the watcher is inactive (and not pending either). |
1870 | .IP "w\->set ([args])" 4 |
2671 | .IP "w\->set ([args])" 4 |
1871 | .IX Item "w->set ([args])" |
2672 | .IX Item "w->set ([args])" |
1872 | Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be |
2673 | Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be |
1873 | called at least once. Unlike the C counterpart, an active watcher gets |
2674 | called at least once. Unlike the C counterpart, an active watcher gets |
1874 | automatically stopped and restarted. |
2675 | automatically stopped and restarted when reconfiguring it with this |
|
|
2676 | method. |
1875 | .IP "w\->start ()" 4 |
2677 | .IP "w\->start ()" 4 |
1876 | .IX Item "w->start ()" |
2678 | .IX Item "w->start ()" |
1877 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument as the |
2679 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the |
1878 | constructor already takes the loop. |
2680 | constructor already stores the event loop. |
1879 | .IP "w\->stop ()" 4 |
2681 | .IP "w\->stop ()" 4 |
1880 | .IX Item "w->stop ()" |
2682 | .IX Item "w->stop ()" |
1881 | Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. |
2683 | Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. |
1882 | .ie n .IP "w\->again () ""ev::timer""\fR, \f(CW""ev::periodic"" only" 4 |
2684 | .ie n .IP "w\->again () (""ev::timer""\fR, \f(CW""ev::periodic"" only)" 4 |
1883 | .el .IP "w\->again () \f(CWev::timer\fR, \f(CWev::periodic\fR only" 4 |
2685 | .el .IP "w\->again () (\f(CWev::timer\fR, \f(CWev::periodic\fR only)" 4 |
1884 | .IX Item "w->again () ev::timer, ev::periodic only" |
2686 | .IX Item "w->again () (ev::timer, ev::periodic only)" |
1885 | For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding |
2687 | For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding |
1886 | \&\f(CW\*(C`ev_TYPE_again\*(C'\fR function. |
2688 | \&\f(CW\*(C`ev_TYPE_again\*(C'\fR function. |
1887 | .ie n .IP "w\->sweep () ""ev::embed"" only" 4 |
2689 | .ie n .IP "w\->sweep () (""ev::embed"" only)" 4 |
1888 | .el .IP "w\->sweep () \f(CWev::embed\fR only" 4 |
2690 | .el .IP "w\->sweep () (\f(CWev::embed\fR only)" 4 |
1889 | .IX Item "w->sweep () ev::embed only" |
2691 | .IX Item "w->sweep () (ev::embed only)" |
1890 | Invokes \f(CW\*(C`ev_embed_sweep\*(C'\fR. |
2692 | Invokes \f(CW\*(C`ev_embed_sweep\*(C'\fR. |
1891 | .ie n .IP "w\->update () ""ev::stat"" only" 4 |
2693 | .ie n .IP "w\->update () (""ev::stat"" only)" 4 |
1892 | .el .IP "w\->update () \f(CWev::stat\fR only" 4 |
2694 | .el .IP "w\->update () (\f(CWev::stat\fR only)" 4 |
1893 | .IX Item "w->update () ev::stat only" |
2695 | .IX Item "w->update () (ev::stat only)" |
1894 | Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR. |
2696 | Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR. |
1895 | .RE |
2697 | .RE |
1896 | .RS 4 |
2698 | .RS 4 |
1897 | .RE |
2699 | .RE |
1898 | .PP |
2700 | .PP |
… | |
… | |
1900 | the constructor. |
2702 | the constructor. |
1901 | .PP |
2703 | .PP |
1902 | .Vb 4 |
2704 | .Vb 4 |
1903 | \& class myclass |
2705 | \& class myclass |
1904 | \& { |
2706 | \& { |
1905 | \& ev_io io; void io_cb (ev::io &w, int revents); |
2707 | \& ev::io io; void io_cb (ev::io &w, int revents); |
1906 | \& ev_idle idle void idle_cb (ev::idle &w, int revents); |
2708 | \& ev:idle idle void idle_cb (ev::idle &w, int revents); |
1907 | .Ve |
2709 | \& |
1908 | .PP |
|
|
1909 | .Vb 2 |
|
|
1910 | \& myclass (); |
2710 | \& myclass (int fd) |
1911 | \& } |
|
|
1912 | .Ve |
|
|
1913 | .PP |
|
|
1914 | .Vb 6 |
|
|
1915 | \& myclass::myclass (int fd) |
|
|
1916 | \& : io (this, &myclass::io_cb), |
|
|
1917 | \& idle (this, &myclass::idle_cb) |
|
|
1918 | \& { |
2711 | \& { |
|
|
2712 | \& io .set <myclass, &myclass::io_cb > (this); |
|
|
2713 | \& idle.set <myclass, &myclass::idle_cb> (this); |
|
|
2714 | \& |
1919 | \& io.start (fd, ev::READ); |
2715 | \& io.start (fd, ev::READ); |
|
|
2716 | \& } |
1920 | \& } |
2717 | \& }; |
1921 | .Ve |
2718 | .Ve |
|
|
2719 | .SH "OTHER LANGUAGE BINDINGS" |
|
|
2720 | .IX Header "OTHER LANGUAGE BINDINGS" |
|
|
2721 | Libev does not offer other language bindings itself, but bindings for a |
|
|
2722 | numbe rof languages exist in the form of third-party packages. If you know |
|
|
2723 | any interesting language binding in addition to the ones listed here, drop |
|
|
2724 | me a note. |
|
|
2725 | .IP "Perl" 4 |
|
|
2726 | .IX Item "Perl" |
|
|
2727 | The \s-1EV\s0 module implements the full libev \s-1API\s0 and is actually used to test |
|
|
2728 | libev. \s-1EV\s0 is developed together with libev. Apart from the \s-1EV\s0 core module, |
|
|
2729 | there are additional modules that implement libev-compatible interfaces |
|
|
2730 | to \f(CW\*(C`libadns\*(C'\fR (\f(CW\*(C`EV::ADNS\*(C'\fR), \f(CW\*(C`Net::SNMP\*(C'\fR (\f(CW\*(C`Net::SNMP::EV\*(C'\fR) and the |
|
|
2731 | \&\f(CW\*(C`libglib\*(C'\fR event core (\f(CW\*(C`Glib::EV\*(C'\fR and \f(CW\*(C`EV::Glib\*(C'\fR). |
|
|
2732 | .Sp |
|
|
2733 | It can be found and installed via \s-1CPAN\s0, its homepage is found at |
|
|
2734 | <http://software.schmorp.de/pkg/EV>. |
|
|
2735 | .IP "Ruby" 4 |
|
|
2736 | .IX Item "Ruby" |
|
|
2737 | Tony Arcieri has written a ruby extension that offers access to a subset |
|
|
2738 | of the libev \s-1API\s0 and adds filehandle abstractions, asynchronous \s-1DNS\s0 and |
|
|
2739 | more on top of it. It can be found via gem servers. Its homepage is at |
|
|
2740 | <http://rev.rubyforge.org/>. |
|
|
2741 | .IP "D" 4 |
|
|
2742 | .IX Item "D" |
|
|
2743 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
|
|
2744 | be found at <http://git.llucax.com.ar/?p=software/ev.d.git;a=summary>. |
1922 | .SH "MACRO MAGIC" |
2745 | .SH "MACRO MAGIC" |
1923 | .IX Header "MACRO MAGIC" |
2746 | .IX Header "MACRO MAGIC" |
1924 | Libev can be compiled with a variety of options, the most fundemantal is |
2747 | Libev can be compiled with a variety of options, the most fundamantal |
1925 | \&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines wether (most) functions and |
2748 | of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) |
1926 | callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
2749 | functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
1927 | .PP |
2750 | .PP |
1928 | To make it easier to write programs that cope with either variant, the |
2751 | To make it easier to write programs that cope with either variant, the |
1929 | following macros are defined: |
2752 | following macros are defined: |
1930 | .ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4 |
2753 | .ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4 |
1931 | .el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4 |
2754 | .el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4 |
… | |
… | |
1950 | \&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example: |
2773 | \&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example: |
1951 | .Sp |
2774 | .Sp |
1952 | .Vb 2 |
2775 | .Vb 2 |
1953 | \& // this is how ev_unref is being declared |
2776 | \& // this is how ev_unref is being declared |
1954 | \& static void ev_unref (EV_P); |
2777 | \& static void ev_unref (EV_P); |
1955 | .Ve |
2778 | \& |
1956 | .Sp |
|
|
1957 | .Vb 2 |
|
|
1958 | \& // this is how you can declare your typical callback |
2779 | \& // this is how you can declare your typical callback |
1959 | \& static void cb (EV_P_ ev_timer *w, int revents) |
2780 | \& static void cb (EV_P_ ev_timer *w, int revents) |
1960 | .Ve |
2781 | .Ve |
1961 | .Sp |
2782 | .Sp |
1962 | It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite |
2783 | It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite |
… | |
… | |
1964 | .ie n .IP """EV_DEFAULT""\fR, \f(CW""EV_DEFAULT_""" 4 |
2785 | .ie n .IP """EV_DEFAULT""\fR, \f(CW""EV_DEFAULT_""" 4 |
1965 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
2786 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
1966 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
2787 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
1967 | Similar to the other two macros, this gives you the value of the default |
2788 | Similar to the other two macros, this gives you the value of the default |
1968 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). |
2789 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). |
|
|
2790 | .ie n .IP """EV_DEFAULT_UC""\fR, \f(CW""EV_DEFAULT_UC_""" 4 |
|
|
2791 | .el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4 |
|
|
2792 | .IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_" |
|
|
2793 | Usage identical to \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR, but requires that the |
|
|
2794 | default loop has been initialised (\f(CW\*(C`UC\*(C'\fR == unchecked). Their behaviour |
|
|
2795 | is undefined when the default loop has not been initialised by a previous |
|
|
2796 | 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. |
|
|
2797 | .Sp |
|
|
2798 | It is often prudent to use \f(CW\*(C`EV_DEFAULT\*(C'\fR when initialising the first |
|
|
2799 | watcher in a function but use \f(CW\*(C`EV_DEFAULT_UC\*(C'\fR afterwards. |
1969 | .PP |
2800 | .PP |
1970 | Example: Declare and initialise a check watcher, working regardless of |
2801 | Example: Declare and initialise a check watcher, utilising the above |
1971 | wether multiple loops are supported or not. |
2802 | macros so it will work regardless of whether multiple loops are supported |
|
|
2803 | or not. |
1972 | .PP |
2804 | .PP |
1973 | .Vb 5 |
2805 | .Vb 5 |
1974 | \& static void |
2806 | \& static void |
1975 | \& check_cb (EV_P_ ev_timer *w, int revents) |
2807 | \& check_cb (EV_P_ ev_timer *w, int revents) |
1976 | \& { |
2808 | \& { |
1977 | \& ev_check_stop (EV_A_ w); |
2809 | \& ev_check_stop (EV_A_ w); |
1978 | \& } |
2810 | \& } |
1979 | .Ve |
2811 | \& |
1980 | .PP |
|
|
1981 | .Vb 4 |
|
|
1982 | \& ev_check check; |
2812 | \& ev_check check; |
1983 | \& ev_check_init (&check, check_cb); |
2813 | \& ev_check_init (&check, check_cb); |
1984 | \& ev_check_start (EV_DEFAULT_ &check); |
2814 | \& ev_check_start (EV_DEFAULT_ &check); |
1985 | \& ev_loop (EV_DEFAULT_ 0); |
2815 | \& ev_loop (EV_DEFAULT_ 0); |
1986 | .Ve |
2816 | .Ve |
1987 | .SH "EMBEDDING" |
2817 | .SH "EMBEDDING" |
1988 | .IX Header "EMBEDDING" |
2818 | .IX Header "EMBEDDING" |
1989 | Libev can (and often is) directly embedded into host |
2819 | Libev can (and often is) directly embedded into host |
1990 | applications. Examples of applications that embed it include the Deliantra |
2820 | applications. Examples of applications that embed it include the Deliantra |
1991 | Game Server, the \s-1EV\s0 perl module, the \s-1GNU\s0 Virtual Private Ethernet (gvpe) |
2821 | Game Server, the \s-1EV\s0 perl module, the \s-1GNU\s0 Virtual Private Ethernet (gvpe) |
1992 | and rxvt\-unicode. |
2822 | and rxvt-unicode. |
1993 | .PP |
2823 | .PP |
1994 | The goal is to enable you to just copy the neecssary files into your |
2824 | The goal is to enable you to just copy the necessary files into your |
1995 | source directory without having to change even a single line in them, so |
2825 | source directory without having to change even a single line in them, so |
1996 | you can easily upgrade by simply copying (or having a checked-out copy of |
2826 | you can easily upgrade by simply copying (or having a checked-out copy of |
1997 | libev somewhere in your source tree). |
2827 | libev somewhere in your source tree). |
1998 | .Sh "\s-1FILESETS\s0" |
2828 | .Sh "\s-1FILESETS\s0" |
1999 | .IX Subsection "FILESETS" |
2829 | .IX Subsection "FILESETS" |
… | |
… | |
2032 | .Vb 4 |
2862 | .Vb 4 |
2033 | \& ev.h |
2863 | \& ev.h |
2034 | \& ev.c |
2864 | \& ev.c |
2035 | \& ev_vars.h |
2865 | \& ev_vars.h |
2036 | \& ev_wrap.h |
2866 | \& ev_wrap.h |
2037 | .Ve |
2867 | \& |
2038 | .PP |
|
|
2039 | .Vb 1 |
|
|
2040 | \& ev_win32.c required on win32 platforms only |
2868 | \& ev_win32.c required on win32 platforms only |
2041 | .Ve |
2869 | \& |
2042 | .PP |
|
|
2043 | .Vb 5 |
|
|
2044 | \& ev_select.c only when select backend is enabled (which is by default) |
2870 | \& ev_select.c only when select backend is enabled (which is enabled by default) |
2045 | \& ev_poll.c only when poll backend is enabled (disabled by default) |
2871 | \& ev_poll.c only when poll backend is enabled (disabled by default) |
2046 | \& ev_epoll.c only when the epoll backend is enabled (disabled by default) |
2872 | \& ev_epoll.c only when the epoll backend is enabled (disabled by default) |
2047 | \& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
2873 | \& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
2048 | \& ev_port.c only when the solaris port backend is enabled (disabled by default) |
2874 | \& ev_port.c only when the solaris port backend is enabled (disabled by default) |
2049 | .Ve |
2875 | .Ve |
… | |
… | |
2088 | .Vb 1 |
2914 | .Vb 1 |
2089 | \& libev.m4 |
2915 | \& libev.m4 |
2090 | .Ve |
2916 | .Ve |
2091 | .Sh "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" |
2917 | .Sh "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" |
2092 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
2918 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
2093 | Libev can be configured via a variety of preprocessor symbols you have to define |
2919 | Libev can be configured via a variety of preprocessor symbols you have to |
2094 | before including any of its files. The default is not to build for multiplicity |
2920 | define before including any of its files. The default in the absense of |
2095 | and only include the select backend. |
2921 | autoconf is noted for every option. |
2096 | .IP "\s-1EV_STANDALONE\s0" 4 |
2922 | .IP "\s-1EV_STANDALONE\s0" 4 |
2097 | .IX Item "EV_STANDALONE" |
2923 | .IX Item "EV_STANDALONE" |
2098 | Must always be \f(CW1\fR if you do not use autoconf configuration, which |
2924 | Must always be \f(CW1\fR if you do not use autoconf configuration, which |
2099 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
2925 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
2100 | implementations for some libevent functions (such as logging, which is not |
2926 | implementations for some libevent functions (such as logging, which is not |
… | |
… | |
2104 | .IX Item "EV_USE_MONOTONIC" |
2930 | .IX Item "EV_USE_MONOTONIC" |
2105 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
2931 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
2106 | monotonic clock option at both compiletime and runtime. Otherwise no use |
2932 | monotonic clock option at both compiletime and runtime. Otherwise no use |
2107 | of the monotonic clock option will be attempted. If you enable this, you |
2933 | of the monotonic clock option will be attempted. If you enable this, you |
2108 | usually have to link against librt or something similar. Enabling it when |
2934 | usually have to link against librt or something similar. Enabling it when |
2109 | the functionality isn't available is safe, though, althoguh you have |
2935 | the functionality isn't available is safe, though, although you have |
2110 | to make sure you link against any libraries where the \f(CW\*(C`clock_gettime\*(C'\fR |
2936 | to make sure you link against any libraries where the \f(CW\*(C`clock_gettime\*(C'\fR |
2111 | function is hiding in (often \fI\-lrt\fR). |
2937 | function is hiding in (often \fI\-lrt\fR). |
2112 | .IP "\s-1EV_USE_REALTIME\s0" 4 |
2938 | .IP "\s-1EV_USE_REALTIME\s0" 4 |
2113 | .IX Item "EV_USE_REALTIME" |
2939 | .IX Item "EV_USE_REALTIME" |
2114 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
2940 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
2115 | realtime clock option at compiletime (and assume its availability at |
2941 | realtime clock option at compiletime (and assume its availability at |
2116 | runtime if successful). Otherwise no use of the realtime clock option will |
2942 | runtime if successful). Otherwise no use of the realtime clock option will |
2117 | be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR by \f(CW\*(C`clock_get |
2943 | be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR by \f(CW\*(C`clock_get |
2118 | (CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect correctness. See tzhe note about libraries |
2944 | (CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect correctness. See the |
2119 | in the description of \f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though. |
2945 | note about libraries in the description of \f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though. |
|
|
2946 | .IP "\s-1EV_USE_NANOSLEEP\s0" 4 |
|
|
2947 | .IX Item "EV_USE_NANOSLEEP" |
|
|
2948 | If defined to be \f(CW1\fR, libev will assume that \f(CW\*(C`nanosleep ()\*(C'\fR is available |
|
|
2949 | and will use it for delays. Otherwise it will use \f(CW\*(C`select ()\*(C'\fR. |
|
|
2950 | .IP "\s-1EV_USE_EVENTFD\s0" 4 |
|
|
2951 | .IX Item "EV_USE_EVENTFD" |
|
|
2952 | If defined to be \f(CW1\fR, then libev will assume that \f(CW\*(C`eventfd ()\*(C'\fR is |
|
|
2953 | available and will probe for kernel support at runtime. This will improve |
|
|
2954 | \&\f(CW\*(C`ev_signal\*(C'\fR and \f(CW\*(C`ev_async\*(C'\fR performance and reduce resource consumption. |
|
|
2955 | If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc |
|
|
2956 | 2.7 or newer, otherwise disabled. |
2120 | .IP "\s-1EV_USE_SELECT\s0" 4 |
2957 | .IP "\s-1EV_USE_SELECT\s0" 4 |
2121 | .IX Item "EV_USE_SELECT" |
2958 | .IX Item "EV_USE_SELECT" |
2122 | If undefined or defined to be \f(CW1\fR, libev will compile in support for the |
2959 | If undefined or defined to be \f(CW1\fR, libev will compile in support for the |
2123 | \&\f(CW\*(C`select\*(C'\fR(2) backend. No attempt at autodetection will be done: if no |
2960 | \&\f(CW\*(C`select\*(C'\fR(2) backend. No attempt at autodetection will be done: if no |
2124 | other method takes over, select will be it. Otherwise the select backend |
2961 | other method takes over, select will be it. Otherwise the select backend |
… | |
… | |
2139 | wants osf handles on win32 (this is the case when the select to |
2976 | wants osf handles on win32 (this is the case when the select to |
2140 | be used is the winsock select). This means that it will call |
2977 | be used is the winsock select). This means that it will call |
2141 | \&\f(CW\*(C`_get_osfhandle\*(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise, |
2978 | \&\f(CW\*(C`_get_osfhandle\*(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise, |
2142 | it is assumed that all these functions actually work on fds, even |
2979 | it is assumed that all these functions actually work on fds, even |
2143 | on win32. Should not be defined on non\-win32 platforms. |
2980 | on win32. Should not be defined on non\-win32 platforms. |
|
|
2981 | .IP "\s-1EV_FD_TO_WIN32_HANDLE\s0" 4 |
|
|
2982 | .IX Item "EV_FD_TO_WIN32_HANDLE" |
|
|
2983 | If \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR is enabled, then libev needs a way to map |
|
|
2984 | file descriptors to socket handles. When not defining this symbol (the |
|
|
2985 | default), then libev will call \f(CW\*(C`_get_osfhandle\*(C'\fR, which is usually |
|
|
2986 | correct. In some cases, programs use their own file descriptor management, |
|
|
2987 | in which case they can provide this function to map fds to socket handles. |
2144 | .IP "\s-1EV_USE_POLL\s0" 4 |
2988 | .IP "\s-1EV_USE_POLL\s0" 4 |
2145 | .IX Item "EV_USE_POLL" |
2989 | .IX Item "EV_USE_POLL" |
2146 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
2990 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
2147 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
2991 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
2148 | takes precedence over select. |
2992 | takes precedence over select. |
2149 | .IP "\s-1EV_USE_EPOLL\s0" 4 |
2993 | .IP "\s-1EV_USE_EPOLL\s0" 4 |
2150 | .IX Item "EV_USE_EPOLL" |
2994 | .IX Item "EV_USE_EPOLL" |
2151 | If defined to be \f(CW1\fR, libev will compile in support for the Linux |
2995 | If defined to be \f(CW1\fR, libev will compile in support for the Linux |
2152 | \&\f(CW\*(C`epoll\*(C'\fR(7) backend. Its availability will be detected at runtime, |
2996 | \&\f(CW\*(C`epoll\*(C'\fR(7) backend. Its availability will be detected at runtime, |
2153 | otherwise another method will be used as fallback. This is the |
2997 | otherwise another method will be used as fallback. This is the preferred |
2154 | preferred backend for GNU/Linux systems. |
2998 | backend for GNU/Linux systems. If undefined, it will be enabled if the |
|
|
2999 | headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
2155 | .IP "\s-1EV_USE_KQUEUE\s0" 4 |
3000 | .IP "\s-1EV_USE_KQUEUE\s0" 4 |
2156 | .IX Item "EV_USE_KQUEUE" |
3001 | .IX Item "EV_USE_KQUEUE" |
2157 | If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style |
3002 | If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style |
2158 | \&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime, |
3003 | \&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime, |
2159 | otherwise another method will be used as fallback. This is the preferred |
3004 | otherwise another method will be used as fallback. This is the preferred |
… | |
… | |
2170 | otherwise another method will be used as fallback. This is the preferred |
3015 | otherwise another method will be used as fallback. This is the preferred |
2171 | backend for Solaris 10 systems. |
3016 | backend for Solaris 10 systems. |
2172 | .IP "\s-1EV_USE_DEVPOLL\s0" 4 |
3017 | .IP "\s-1EV_USE_DEVPOLL\s0" 4 |
2173 | .IX Item "EV_USE_DEVPOLL" |
3018 | .IX Item "EV_USE_DEVPOLL" |
2174 | reserved for future expansion, works like the \s-1USE\s0 symbols above. |
3019 | reserved for future expansion, works like the \s-1USE\s0 symbols above. |
|
|
3020 | .IP "\s-1EV_USE_INOTIFY\s0" 4 |
|
|
3021 | .IX Item "EV_USE_INOTIFY" |
|
|
3022 | If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify |
|
|
3023 | interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will |
|
|
3024 | be detected at runtime. If undefined, it will be enabled if the headers |
|
|
3025 | indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
|
|
3026 | .IP "\s-1EV_ATOMIC_T\s0" 4 |
|
|
3027 | .IX Item "EV_ATOMIC_T" |
|
|
3028 | Libev requires an integer type (suitable for storing \f(CW0\fR or \f(CW1\fR) whose |
|
|
3029 | access is atomic with respect to other threads or signal contexts. No such |
|
|
3030 | type is easily found in the C language, so you can provide your own type |
|
|
3031 | that you know is safe for your purposes. It is used both for signal handler \*(L"locking\*(R" |
|
|
3032 | as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR watchers. |
|
|
3033 | .Sp |
|
|
3034 | In the absense of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR |
|
|
3035 | (from \fIsignal.h\fR), which is usually good enough on most platforms. |
2175 | .IP "\s-1EV_H\s0" 4 |
3036 | .IP "\s-1EV_H\s0" 4 |
2176 | .IX Item "EV_H" |
3037 | .IX Item "EV_H" |
2177 | The name of the \fIev.h\fR header file used to include it. The default if |
3038 | The name of the \fIev.h\fR header file used to include it. The default if |
2178 | undefined is \f(CW\*(C`<ev.h>\*(C'\fR in \fIevent.h\fR and \f(CW"ev.h"\fR in \fIev.c\fR. This |
3039 | undefined is \f(CW"ev.h"\fR in \fIevent.h\fR, \fIev.c\fR and \fIev++.h\fR. This can be |
2179 | can be used to virtually rename the \fIev.h\fR header file in case of conflicts. |
3040 | used to virtually rename the \fIev.h\fR header file in case of conflicts. |
2180 | .IP "\s-1EV_CONFIG_H\s0" 4 |
3041 | .IP "\s-1EV_CONFIG_H\s0" 4 |
2181 | .IX Item "EV_CONFIG_H" |
3042 | .IX Item "EV_CONFIG_H" |
2182 | If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override |
3043 | If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override |
2183 | \&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to |
3044 | \&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to |
2184 | \&\f(CW\*(C`EV_H\*(C'\fR, above. |
3045 | \&\f(CW\*(C`EV_H\*(C'\fR, above. |
2185 | .IP "\s-1EV_EVENT_H\s0" 4 |
3046 | .IP "\s-1EV_EVENT_H\s0" 4 |
2186 | .IX Item "EV_EVENT_H" |
3047 | .IX Item "EV_EVENT_H" |
2187 | Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea |
3048 | Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea |
2188 | of how the \fIevent.h\fR header can be found. |
3049 | of how the \fIevent.h\fR header can be found, the default is \f(CW"event.h"\fR. |
2189 | .IP "\s-1EV_PROTOTYPES\s0" 4 |
3050 | .IP "\s-1EV_PROTOTYPES\s0" 4 |
2190 | .IX Item "EV_PROTOTYPES" |
3051 | .IX Item "EV_PROTOTYPES" |
2191 | If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function |
3052 | If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function |
2192 | prototypes, but still define all the structs and other symbols. This is |
3053 | prototypes, but still define all the structs and other symbols. This is |
2193 | occasionally useful if you want to provide your own wrapper functions |
3054 | occasionally useful if you want to provide your own wrapper functions |
… | |
… | |
2197 | If undefined or defined to \f(CW1\fR, then all event-loop-specific functions |
3058 | If undefined or defined to \f(CW1\fR, then all event-loop-specific functions |
2198 | will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create |
3059 | will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create |
2199 | additional independent event loops. Otherwise there will be no support |
3060 | additional independent event loops. Otherwise there will be no support |
2200 | for multiple event loops and there is no first event loop pointer |
3061 | for multiple event loops and there is no first event loop pointer |
2201 | argument. Instead, all functions act on the single default loop. |
3062 | argument. Instead, all functions act on the single default loop. |
|
|
3063 | .IP "\s-1EV_MINPRI\s0" 4 |
|
|
3064 | .IX Item "EV_MINPRI" |
|
|
3065 | .PD 0 |
|
|
3066 | .IP "\s-1EV_MAXPRI\s0" 4 |
|
|
3067 | .IX Item "EV_MAXPRI" |
|
|
3068 | .PD |
|
|
3069 | The range of allowed priorities. \f(CW\*(C`EV_MINPRI\*(C'\fR must be smaller or equal to |
|
|
3070 | \&\f(CW\*(C`EV_MAXPRI\*(C'\fR, but otherwise there are no non-obvious limitations. You can |
|
|
3071 | provide for more priorities by overriding those symbols (usually defined |
|
|
3072 | to be \f(CW\*(C`\-2\*(C'\fR and \f(CW2\fR, respectively). |
|
|
3073 | .Sp |
|
|
3074 | When doing priority-based operations, libev usually has to linearly search |
|
|
3075 | all the priorities, so having many of them (hundreds) uses a lot of space |
|
|
3076 | and time, so using the defaults of five priorities (\-2 .. +2) is usually |
|
|
3077 | fine. |
|
|
3078 | .Sp |
|
|
3079 | If your embedding app does not need any priorities, defining these both to |
|
|
3080 | \&\f(CW0\fR will save some memory and cpu. |
2202 | .IP "\s-1EV_PERIODIC_ENABLE\s0" 4 |
3081 | .IP "\s-1EV_PERIODIC_ENABLE\s0" 4 |
2203 | .IX Item "EV_PERIODIC_ENABLE" |
3082 | .IX Item "EV_PERIODIC_ENABLE" |
2204 | If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If |
3083 | If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If |
|
|
3084 | defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of |
|
|
3085 | code. |
|
|
3086 | .IP "\s-1EV_IDLE_ENABLE\s0" 4 |
|
|
3087 | .IX Item "EV_IDLE_ENABLE" |
|
|
3088 | If undefined or defined to be \f(CW1\fR, then idle watchers are supported. If |
2205 | defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of |
3089 | defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of |
2206 | code. |
3090 | code. |
2207 | .IP "\s-1EV_EMBED_ENABLE\s0" 4 |
3091 | .IP "\s-1EV_EMBED_ENABLE\s0" 4 |
2208 | .IX Item "EV_EMBED_ENABLE" |
3092 | .IX Item "EV_EMBED_ENABLE" |
2209 | If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If |
3093 | If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If |
… | |
… | |
2214 | defined to be \f(CW0\fR, then they are not. |
3098 | defined to be \f(CW0\fR, then they are not. |
2215 | .IP "\s-1EV_FORK_ENABLE\s0" 4 |
3099 | .IP "\s-1EV_FORK_ENABLE\s0" 4 |
2216 | .IX Item "EV_FORK_ENABLE" |
3100 | .IX Item "EV_FORK_ENABLE" |
2217 | If undefined or defined to be \f(CW1\fR, then fork watchers are supported. If |
3101 | If undefined or defined to be \f(CW1\fR, then fork watchers are supported. If |
2218 | defined to be \f(CW0\fR, then they are not. |
3102 | defined to be \f(CW0\fR, then they are not. |
|
|
3103 | .IP "\s-1EV_ASYNC_ENABLE\s0" 4 |
|
|
3104 | .IX Item "EV_ASYNC_ENABLE" |
|
|
3105 | If undefined or defined to be \f(CW1\fR, then async watchers are supported. If |
|
|
3106 | defined to be \f(CW0\fR, then they are not. |
2219 | .IP "\s-1EV_MINIMAL\s0" 4 |
3107 | .IP "\s-1EV_MINIMAL\s0" 4 |
2220 | .IX Item "EV_MINIMAL" |
3108 | .IX Item "EV_MINIMAL" |
2221 | If you need to shave off some kilobytes of code at the expense of some |
3109 | If you need to shave off some kilobytes of code at the expense of some |
2222 | speed, define this symbol to \f(CW1\fR. Currently only used for gcc to override |
3110 | speed, define this symbol to \f(CW1\fR. Currently this is used to override some |
2223 | some inlining decisions, saves roughly 30% codesize of amd64. |
3111 | inlining decisions, saves roughly 30% codesize of amd64. It also selects a |
|
|
3112 | much smaller 2\-heap for timer management over the default 4\-heap. |
2224 | .IP "\s-1EV_PID_HASHSIZE\s0" 4 |
3113 | .IP "\s-1EV_PID_HASHSIZE\s0" 4 |
2225 | .IX Item "EV_PID_HASHSIZE" |
3114 | .IX Item "EV_PID_HASHSIZE" |
2226 | \&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by |
3115 | \&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by |
2227 | pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more |
3116 | pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more |
2228 | than enough. If you need to manage thousands of children you might want to |
3117 | than enough. If you need to manage thousands of children you might want to |
2229 | increase this value. |
3118 | increase this value (\fImust\fR be a power of two). |
|
|
3119 | .IP "\s-1EV_INOTIFY_HASHSIZE\s0" 4 |
|
|
3120 | .IX Item "EV_INOTIFY_HASHSIZE" |
|
|
3121 | \&\f(CW\*(C`ev_stat\*(C'\fR watchers use a small hash table to distribute workload by |
|
|
3122 | inotify watch id. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), |
|
|
3123 | usually more than enough. If you need to manage thousands of \f(CW\*(C`ev_stat\*(C'\fR |
|
|
3124 | watchers you might want to increase this value (\fImust\fR be a power of |
|
|
3125 | two). |
|
|
3126 | .IP "\s-1EV_USE_4HEAP\s0" 4 |
|
|
3127 | .IX Item "EV_USE_4HEAP" |
|
|
3128 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
|
|
3129 | timer and periodics heap, libev uses a 4\-heap when this symbol is defined |
|
|
3130 | to \f(CW1\fR. The 4\-heap uses more complicated (longer) code but has |
|
|
3131 | noticably faster performance with many (thousands) of watchers. |
|
|
3132 | .Sp |
|
|
3133 | The default is \f(CW1\fR unless \f(CW\*(C`EV_MINIMAL\*(C'\fR is set in which case it is \f(CW0\fR |
|
|
3134 | (disabled). |
|
|
3135 | .IP "\s-1EV_HEAP_CACHE_AT\s0" 4 |
|
|
3136 | .IX Item "EV_HEAP_CACHE_AT" |
|
|
3137 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
|
|
3138 | timer and periodics heap, libev can cache the timestamp (\fIat\fR) within |
|
|
3139 | the heap structure (selected by defining \f(CW\*(C`EV_HEAP_CACHE_AT\*(C'\fR to \f(CW1\fR), |
|
|
3140 | which uses 8\-12 bytes more per watcher and a few hundred bytes more code, |
|
|
3141 | but avoids random read accesses on heap changes. This improves performance |
|
|
3142 | noticably with with many (hundreds) of watchers. |
|
|
3143 | .Sp |
|
|
3144 | The default is \f(CW1\fR unless \f(CW\*(C`EV_MINIMAL\*(C'\fR is set in which case it is \f(CW0\fR |
|
|
3145 | (disabled). |
|
|
3146 | .IP "\s-1EV_VERIFY\s0" 4 |
|
|
3147 | .IX Item "EV_VERIFY" |
|
|
3148 | Controls how much internal verification (see \f(CW\*(C`ev_loop_verify ()\*(C'\fR) will |
|
|
3149 | be done: If set to \f(CW0\fR, no internal verification code will be compiled |
|
|
3150 | in. If set to \f(CW1\fR, then verification code will be compiled in, but not |
|
|
3151 | called. If set to \f(CW2\fR, then the internal verification code will be |
|
|
3152 | called once per loop, which can slow down libev. If set to \f(CW3\fR, then the |
|
|
3153 | verification code will be called very frequently, which will slow down |
|
|
3154 | libev considerably. |
|
|
3155 | .Sp |
|
|
3156 | The default is \f(CW1\fR, unless \f(CW\*(C`EV_MINIMAL\*(C'\fR is set, in which case it will be |
|
|
3157 | \&\f(CW0.\fR |
2230 | .IP "\s-1EV_COMMON\s0" 4 |
3158 | .IP "\s-1EV_COMMON\s0" 4 |
2231 | .IX Item "EV_COMMON" |
3159 | .IX Item "EV_COMMON" |
2232 | By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining |
3160 | By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining |
2233 | this macro to a something else you can include more and other types of |
3161 | this macro to a something else you can include more and other types of |
2234 | members. You have to define it each time you include one of the files, |
3162 | members. You have to define it each time you include one of the files, |
… | |
… | |
2249 | .IP "ev_set_cb (ev, cb)" 4 |
3177 | .IP "ev_set_cb (ev, cb)" 4 |
2250 | .IX Item "ev_set_cb (ev, cb)" |
3178 | .IX Item "ev_set_cb (ev, cb)" |
2251 | .PD |
3179 | .PD |
2252 | Can be used to change the callback member declaration in each watcher, |
3180 | Can be used to change the callback member declaration in each watcher, |
2253 | and the way callbacks are invoked and set. Must expand to a struct member |
3181 | and the way callbacks are invoked and set. Must expand to a struct member |
2254 | definition and a statement, respectively. See the \fIev.v\fR header file for |
3182 | definition and a statement, respectively. See the \fIev.h\fR header file for |
2255 | their default definitions. One possible use for overriding these is to |
3183 | their default definitions. One possible use for overriding these is to |
2256 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
3184 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
2257 | method calls instead of plain function calls in \*(C+. |
3185 | method calls instead of plain function calls in \*(C+. |
|
|
3186 | .Sh "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0" |
|
|
3187 | .IX Subsection "EXPORTED API SYMBOLS" |
|
|
3188 | If you need to re-export the \s-1API\s0 (e.g. via a dll) and you need a list of |
|
|
3189 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
|
|
3190 | all public symbols, one per line: |
|
|
3191 | .PP |
|
|
3192 | .Vb 2 |
|
|
3193 | \& Symbols.ev for libev proper |
|
|
3194 | \& Symbols.event for the libevent emulation |
|
|
3195 | .Ve |
|
|
3196 | .PP |
|
|
3197 | This can also be used to rename all public symbols to avoid clashes with |
|
|
3198 | multiple versions of libev linked together (which is obviously bad in |
|
|
3199 | itself, but sometimes it is inconvinient to avoid this). |
|
|
3200 | .PP |
|
|
3201 | A sed command like this will create wrapper \f(CW\*(C`#define\*(C'\fR's that you need to |
|
|
3202 | include before including \fIev.h\fR: |
|
|
3203 | .PP |
|
|
3204 | .Vb 1 |
|
|
3205 | \& <Symbols.ev sed \-e "s/.*/#define & myprefix_&/" >wrap.h |
|
|
3206 | .Ve |
|
|
3207 | .PP |
|
|
3208 | This would create a file \fIwrap.h\fR which essentially looks like this: |
|
|
3209 | .PP |
|
|
3210 | .Vb 4 |
|
|
3211 | \& #define ev_backend myprefix_ev_backend |
|
|
3212 | \& #define ev_check_start myprefix_ev_check_start |
|
|
3213 | \& #define ev_check_stop myprefix_ev_check_stop |
|
|
3214 | \& ... |
|
|
3215 | .Ve |
2258 | .Sh "\s-1EXAMPLES\s0" |
3216 | .Sh "\s-1EXAMPLES\s0" |
2259 | .IX Subsection "EXAMPLES" |
3217 | .IX Subsection "EXAMPLES" |
2260 | For a real-world example of a program the includes libev |
3218 | For a real-world example of a program the includes libev |
2261 | verbatim, you can have a look at the \s-1EV\s0 perl module |
3219 | verbatim, you can have a look at the \s-1EV\s0 perl module |
2262 | (<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
3220 | (<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
2263 | the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public |
3221 | the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public |
2264 | interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file |
3222 | interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file |
2265 | will be compiled. It is pretty complex because it provides its own header |
3223 | will be compiled. It is pretty complex because it provides its own header |
2266 | file. |
3224 | file. |
2267 | .Sp |
3225 | .PP |
2268 | The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file |
3226 | The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file |
2269 | that everybody includes and which overrides some autoconf choices: |
3227 | that everybody includes and which overrides some configure choices: |
2270 | .Sp |
3228 | .PP |
2271 | .Vb 4 |
3229 | .Vb 9 |
|
|
3230 | \& #define EV_MINIMAL 1 |
2272 | \& #define EV_USE_POLL 0 |
3231 | \& #define EV_USE_POLL 0 |
2273 | \& #define EV_MULTIPLICITY 0 |
3232 | \& #define EV_MULTIPLICITY 0 |
2274 | \& #define EV_PERIODICS 0 |
3233 | \& #define EV_PERIODIC_ENABLE 0 |
|
|
3234 | \& #define EV_STAT_ENABLE 0 |
|
|
3235 | \& #define EV_FORK_ENABLE 0 |
2275 | \& #define EV_CONFIG_H <config.h> |
3236 | \& #define EV_CONFIG_H <config.h> |
2276 | .Ve |
3237 | \& #define EV_MINPRI 0 |
2277 | .Sp |
3238 | \& #define EV_MAXPRI 0 |
2278 | .Vb 1 |
3239 | \& |
2279 | \& #include "ev++.h" |
3240 | \& #include "ev++.h" |
2280 | .Ve |
3241 | .Ve |
2281 | .Sp |
3242 | .PP |
2282 | And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled: |
3243 | And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled: |
2283 | .Sp |
3244 | .PP |
2284 | .Vb 2 |
3245 | .Vb 2 |
2285 | \& #include "ev_cpp.h" |
3246 | \& #include "ev_cpp.h" |
2286 | \& #include "ev.c" |
3247 | \& #include "ev.c" |
2287 | .Ve |
3248 | .Ve |
|
|
3249 | .SH "THREADS AND COROUTINES" |
|
|
3250 | .IX Header "THREADS AND COROUTINES" |
|
|
3251 | .Sh "\s-1THREADS\s0" |
|
|
3252 | .IX Subsection "THREADS" |
|
|
3253 | Libev itself is completely threadsafe, but it uses no locking. This |
|
|
3254 | means that you can use as many loops as you want in parallel, as long as |
|
|
3255 | only one thread ever calls into one libev function with the same loop |
|
|
3256 | parameter. |
|
|
3257 | .PP |
|
|
3258 | Or put differently: calls with different loop parameters can be done in |
|
|
3259 | parallel from multiple threads, calls with the same loop parameter must be |
|
|
3260 | done serially (but can be done from different threads, as long as only one |
|
|
3261 | thread ever is inside a call at any point in time, e.g. by using a mutex |
|
|
3262 | per loop). |
|
|
3263 | .PP |
|
|
3264 | If you want to know which design is best for your problem, then I cannot |
|
|
3265 | help you but by giving some generic advice: |
|
|
3266 | .IP "\(bu" 4 |
|
|
3267 | most applications have a main thread: use the default libev loop |
|
|
3268 | in that thread, or create a seperate thread running only the default loop. |
|
|
3269 | .Sp |
|
|
3270 | This helps integrating other libraries or software modules that use libev |
|
|
3271 | themselves and don't care/know about threading. |
|
|
3272 | .IP "\(bu" 4 |
|
|
3273 | one loop per thread is usually a good model. |
|
|
3274 | .Sp |
|
|
3275 | Doing this is almost never wrong, sometimes a better-performance model |
|
|
3276 | exists, but it is always a good start. |
|
|
3277 | .IP "\(bu" 4 |
|
|
3278 | other models exist, such as the leader/follower pattern, where one |
|
|
3279 | loop is handed through multiple threads in a kind of round-robbin fashion. |
|
|
3280 | .Sp |
|
|
3281 | Chosing a model is hard \- look around, learn, know that usually you cna do |
|
|
3282 | better than you currently do :\-) |
|
|
3283 | .IP "\(bu" 4 |
|
|
3284 | often you need to talk to some other thread which blocks in the |
|
|
3285 | event loop \- \f(CW\*(C`ev_async\*(C'\fR watchers can be used to wake them up from other |
|
|
3286 | threads safely (or from signal contexts...). |
|
|
3287 | .Sh "\s-1COROUTINES\s0" |
|
|
3288 | .IX Subsection "COROUTINES" |
|
|
3289 | Libev is much more accomodating to coroutines (\*(L"cooperative threads\*(R"): |
|
|
3290 | libev fully supports nesting calls to it's functions from different |
|
|
3291 | coroutines (e.g. you can call \f(CW\*(C`ev_loop\*(C'\fR on the same loop from two |
|
|
3292 | different coroutines and switch freely between both coroutines running the |
|
|
3293 | loop, as long as you don't confuse yourself). The only exception is that |
|
|
3294 | you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. |
|
|
3295 | .PP |
|
|
3296 | Care has been invested into making sure that libev does not keep local |
|
|
3297 | state inside \f(CW\*(C`ev_loop\*(C'\fR, and other calls do not usually allow coroutine |
|
|
3298 | switches. |
2288 | .SH "COMPLEXITIES" |
3299 | .SH "COMPLEXITIES" |
2289 | .IX Header "COMPLEXITIES" |
3300 | .IX Header "COMPLEXITIES" |
2290 | In this section the complexities of (many of) the algorithms used inside |
3301 | In this section the complexities of (many of) the algorithms used inside |
2291 | libev will be explained. For complexity discussions about backends see the |
3302 | libev will be explained. For complexity discussions about backends see the |
2292 | documentation for \f(CW\*(C`ev_default_init\*(C'\fR. |
3303 | documentation for \f(CW\*(C`ev_default_init\*(C'\fR. |
2293 | .RS 4 |
3304 | .PP |
|
|
3305 | All of the following are about amortised time: If an array needs to be |
|
|
3306 | extended, libev needs to realloc and move the whole array, but this |
|
|
3307 | happens asymptotically never with higher number of elements, so O(1) might |
|
|
3308 | mean it might do a lengthy realloc operation in rare cases, but on average |
|
|
3309 | it is much faster and asymptotically approaches constant time. |
2294 | .IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4 |
3310 | .IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4 |
2295 | .IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" |
3311 | .IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" |
|
|
3312 | This means that, when you have a watcher that triggers in one hour and |
|
|
3313 | there are 100 watchers that would trigger before that then inserting will |
|
|
3314 | have to skip roughly seven (\f(CW\*(C`ld 100\*(C'\fR) of these watchers. |
|
|
3315 | .IP "Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers)" 4 |
|
|
3316 | .IX Item "Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers)" |
|
|
3317 | That means that changing a timer costs less than removing/adding them |
|
|
3318 | as only the relative motion in the event queue has to be paid for. |
|
|
3319 | .IP "Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1)" 4 |
|
|
3320 | .IX Item "Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1)" |
|
|
3321 | These just add the watcher into an array or at the head of a list. |
|
|
3322 | .IP "Stopping check/prepare/idle/fork/async watchers: O(1)" 4 |
|
|
3323 | .IX Item "Stopping check/prepare/idle/fork/async watchers: O(1)" |
2296 | .PD 0 |
3324 | .PD 0 |
2297 | .IP "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 4 |
|
|
2298 | .IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" |
|
|
2299 | .IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4 |
|
|
2300 | .IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)" |
|
|
2301 | .IP "Stopping check/prepare/idle watchers: O(1)" 4 |
|
|
2302 | .IX Item "Stopping check/prepare/idle watchers: O(1)" |
|
|
2303 | .IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))" 4 |
3325 | .IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4 |
2304 | .IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))" |
3326 | .IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))" |
|
|
3327 | .PD |
|
|
3328 | These watchers are stored in lists then need to be walked to find the |
|
|
3329 | correct watcher to remove. The lists are usually short (you don't usually |
|
|
3330 | have many watchers waiting for the same fd or signal). |
2305 | .IP "Finding the next timer per loop iteration: O(1)" 4 |
3331 | .IP "Finding the next timer in each loop iteration: O(1)" 4 |
2306 | .IX Item "Finding the next timer per loop iteration: O(1)" |
3332 | .IX Item "Finding the next timer in each loop iteration: O(1)" |
|
|
3333 | By virtue of using a binary or 4\-heap, the next timer is always found at a |
|
|
3334 | fixed position in the storage array. |
2307 | .IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4 |
3335 | .IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4 |
2308 | .IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" |
3336 | .IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" |
2309 | .IP "Activating one watcher: O(1)" 4 |
3337 | A change means an I/O watcher gets started or stopped, which requires |
2310 | .IX Item "Activating one watcher: O(1)" |
3338 | libev to recalculate its status (and possibly tell the kernel, depending |
2311 | .RE |
3339 | on backend and wether \f(CW\*(C`ev_io_set\*(C'\fR was used). |
2312 | .RS 4 |
3340 | .IP "Activating one watcher (putting it into the pending state): O(1)" 4 |
|
|
3341 | .IX Item "Activating one watcher (putting it into the pending state): O(1)" |
|
|
3342 | .PD 0 |
|
|
3343 | .IP "Priority handling: O(number_of_priorities)" 4 |
|
|
3344 | .IX Item "Priority handling: O(number_of_priorities)" |
2313 | .PD |
3345 | .PD |
|
|
3346 | Priorities are implemented by allocating some space for each |
|
|
3347 | priority. When doing priority-based operations, libev usually has to |
|
|
3348 | linearly search all the priorities, but starting/stopping and activating |
|
|
3349 | watchers becomes O(1) w.r.t. priority handling. |
|
|
3350 | .IP "Sending an ev_async: O(1)" 4 |
|
|
3351 | .IX Item "Sending an ev_async: O(1)" |
|
|
3352 | .PD 0 |
|
|
3353 | .IP "Processing ev_async_send: O(number_of_async_watchers)" 4 |
|
|
3354 | .IX Item "Processing ev_async_send: O(number_of_async_watchers)" |
|
|
3355 | .IP "Processing signals: O(max_signal_number)" 4 |
|
|
3356 | .IX Item "Processing signals: O(max_signal_number)" |
|
|
3357 | .PD |
|
|
3358 | Sending involves a syscall \fIiff\fR there were no other \f(CW\*(C`ev_async_send\*(C'\fR |
|
|
3359 | calls in the current loop iteration. Checking for async and signal events |
|
|
3360 | involves iterating over all running async watchers or all signal numbers. |
|
|
3361 | .SH "Win32 platform limitations and workarounds" |
|
|
3362 | .IX Header "Win32 platform limitations and workarounds" |
|
|
3363 | Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev |
|
|
3364 | requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 |
|
|
3365 | model. Libev still offers limited functionality on this platform in |
|
|
3366 | the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket |
|
|
3367 | descriptors. This only applies when using Win32 natively, not when using |
|
|
3368 | e.g. cygwin. |
|
|
3369 | .PP |
|
|
3370 | Lifting these limitations would basically require the full |
|
|
3371 | re-implementation of the I/O system. If you are into these kinds of |
|
|
3372 | things, then note that glib does exactly that for you in a very portable |
|
|
3373 | way (note also that glib is the slowest event library known to man). |
|
|
3374 | .PP |
|
|
3375 | There is no supported compilation method available on windows except |
|
|
3376 | embedding it into other applications. |
|
|
3377 | .PP |
|
|
3378 | Due to the many, low, and arbitrary limits on the win32 platform and |
|
|
3379 | the abysmal performance of winsockets, using a large number of sockets |
|
|
3380 | is not recommended (and not reasonable). If your program needs to use |
|
|
3381 | more than a hundred or so sockets, then likely it needs to use a totally |
|
|
3382 | different implementation for windows, as libev offers the \s-1POSIX\s0 readiness |
|
|
3383 | notification model, which cannot be implemented efficiently on windows |
|
|
3384 | (microsoft monopoly games). |
|
|
3385 | .IP "The winsocket select function" 4 |
|
|
3386 | .IX Item "The winsocket select function" |
|
|
3387 | The winsocket \f(CW\*(C`select\*(C'\fR function doesn't follow \s-1POSIX\s0 in that it |
|
|
3388 | requires socket \fIhandles\fR and not socket \fIfile descriptors\fR (it is |
|
|
3389 | also extremely buggy). This makes select very inefficient, and also |
|
|
3390 | requires a mapping from file descriptors to socket handles. See the |
|
|
3391 | discussion of the \f(CW\*(C`EV_SELECT_USE_FD_SET\*(C'\fR, \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR and |
|
|
3392 | \&\f(CW\*(C`EV_FD_TO_WIN32_HANDLE\*(C'\fR preprocessor symbols for more info. |
|
|
3393 | .Sp |
|
|
3394 | The configuration for a \*(L"naked\*(R" win32 using the microsoft runtime |
|
|
3395 | libraries and raw winsocket select is: |
|
|
3396 | .Sp |
|
|
3397 | .Vb 2 |
|
|
3398 | \& #define EV_USE_SELECT 1 |
|
|
3399 | \& #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
|
|
3400 | .Ve |
|
|
3401 | .Sp |
|
|
3402 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
|
|
3403 | complexity in the O(nA\*^X) range when using win32. |
|
|
3404 | .IP "Limited number of file descriptors" 4 |
|
|
3405 | .IX Item "Limited number of file descriptors" |
|
|
3406 | Windows has numerous arbitrary (and low) limits on things. |
|
|
3407 | .Sp |
|
|
3408 | Early versions of winsocket's select only supported waiting for a maximum |
|
|
3409 | of \f(CW64\fR handles (probably owning to the fact that all windows kernels |
|
|
3410 | can only wait for \f(CW64\fR things at the same time internally; microsoft |
|
|
3411 | recommends spawning a chain of threads and wait for 63 handles and the |
|
|
3412 | previous thread in each. Great). |
|
|
3413 | .Sp |
|
|
3414 | Newer versions support more handles, but you need to define \f(CW\*(C`FD_SETSIZE\*(C'\fR |
|
|
3415 | to some high number (e.g. \f(CW2048\fR) before compiling the winsocket select |
|
|
3416 | call (which might be in libev or elsewhere, for example, perl does its own |
|
|
3417 | select emulation on windows). |
|
|
3418 | .Sp |
|
|
3419 | Another limit is the number of file descriptors in the microsoft runtime |
|
|
3420 | libraries, which by default is \f(CW64\fR (there must be a hidden \fI64\fR fetish |
|
|
3421 | or something like this inside microsoft). You can increase this by calling |
|
|
3422 | \&\f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR (another |
|
|
3423 | arbitrary limit), but is broken in many versions of the microsoft runtime |
|
|
3424 | libraries. |
|
|
3425 | .Sp |
|
|
3426 | This might get you to about \f(CW512\fR or \f(CW2048\fR sockets (depending on |
|
|
3427 | windows version and/or the phase of the moon). To get more, you need to |
|
|
3428 | wrap all I/O functions and provide your own fd management, but the cost of |
|
|
3429 | calling select (O(nA\*^X)) will likely make this unworkable. |
|
|
3430 | .SH "PORTABILITY REQUIREMENTS" |
|
|
3431 | .IX Header "PORTABILITY REQUIREMENTS" |
|
|
3432 | In addition to a working ISO-C implementation, libev relies on a few |
|
|
3433 | additional extensions: |
|
|
3434 | .ie n .IP """sig_atomic_t volatile"" must be thread-atomic as well" 4 |
|
|
3435 | .el .IP "\f(CWsig_atomic_t volatile\fR must be thread-atomic as well" 4 |
|
|
3436 | .IX Item "sig_atomic_t volatile must be thread-atomic as well" |
|
|
3437 | The type \f(CW\*(C`sig_atomic_t volatile\*(C'\fR (or whatever is defined as |
|
|
3438 | \&\f(CW\*(C`EV_ATOMIC_T\*(C'\fR) must be atomic w.r.t. accesses from different |
|
|
3439 | threads. This is not part of the specification for \f(CW\*(C`sig_atomic_t\*(C'\fR, but is |
|
|
3440 | believed to be sufficiently portable. |
|
|
3441 | .ie n .IP """sigprocmask"" must work in a threaded environment" 4 |
|
|
3442 | .el .IP "\f(CWsigprocmask\fR must work in a threaded environment" 4 |
|
|
3443 | .IX Item "sigprocmask must work in a threaded environment" |
|
|
3444 | Libev uses \f(CW\*(C`sigprocmask\*(C'\fR to temporarily block signals. This is not |
|
|
3445 | allowed in a threaded program (\f(CW\*(C`pthread_sigmask\*(C'\fR has to be used). Typical |
|
|
3446 | pthread implementations will either allow \f(CW\*(C`sigprocmask\*(C'\fR in the \*(L"main |
|
|
3447 | thread\*(R" or will block signals process-wide, both behaviours would |
|
|
3448 | be compatible with libev. Interaction between \f(CW\*(C`sigprocmask\*(C'\fR and |
|
|
3449 | \&\f(CW\*(C`pthread_sigmask\*(C'\fR could complicate things, however. |
|
|
3450 | .Sp |
|
|
3451 | The most portable way to handle signals is to block signals in all threads |
|
|
3452 | except the initial one, and run the default loop in the initial thread as |
|
|
3453 | well. |
|
|
3454 | .ie n .IP """long"" must be large enough for common memory allocation sizes" 4 |
|
|
3455 | .el .IP "\f(CWlong\fR must be large enough for common memory allocation sizes" 4 |
|
|
3456 | .IX Item "long must be large enough for common memory allocation sizes" |
|
|
3457 | To improve portability and simplify using libev, libev uses \f(CW\*(C`long\*(C'\fR |
|
|
3458 | internally instead of \f(CW\*(C`size_t\*(C'\fR when allocating its data structures. On |
|
|
3459 | non-POSIX systems (Microsoft...) this might be unexpectedly low, but |
|
|
3460 | is still at least 31 bits everywhere, which is enough for hundreds of |
|
|
3461 | millions of watchers. |
|
|
3462 | .ie n .IP """double"" must hold a time value in seconds with enough accuracy" 4 |
|
|
3463 | .el .IP "\f(CWdouble\fR must hold a time value in seconds with enough accuracy" 4 |
|
|
3464 | .IX Item "double must hold a time value in seconds with enough accuracy" |
|
|
3465 | The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to |
|
|
3466 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
|
|
3467 | enough for at least into the year 4000. This requirement is fulfilled by |
|
|
3468 | implementations implementing \s-1IEEE\s0 754 (basically all existing ones). |
|
|
3469 | .PP |
|
|
3470 | If you know of other additional requirements drop me a note. |
|
|
3471 | .SH "COMPILER WARNINGS" |
|
|
3472 | .IX Header "COMPILER WARNINGS" |
|
|
3473 | Depending on your compiler and compiler settings, you might get no or a |
|
|
3474 | lot of warnings when compiling libev code. Some people are apparently |
|
|
3475 | scared by this. |
|
|
3476 | .PP |
|
|
3477 | However, these are unavoidable for many reasons. For one, each compiler |
|
|
3478 | has different warnings, and each user has different tastes regarding |
|
|
3479 | warning options. \*(L"Warn-free\*(R" code therefore cannot be a goal except when |
|
|
3480 | targetting a specific compiler and compiler-version. |
|
|
3481 | .PP |
|
|
3482 | Another reason is that some compiler warnings require elaborate |
|
|
3483 | workarounds, or other changes to the code that make it less clear and less |
|
|
3484 | maintainable. |
|
|
3485 | .PP |
|
|
3486 | And of course, some compiler warnings are just plain stupid, or simply |
|
|
3487 | wrong (because they don't actually warn about the cindition their message |
|
|
3488 | seems to warn about). |
|
|
3489 | .PP |
|
|
3490 | While libev is written to generate as few warnings as possible, |
|
|
3491 | \&\*(L"warn-free\*(R" code is not a goal, and it is recommended not to build libev |
|
|
3492 | with any compiler warnings enabled unless you are prepared to cope with |
|
|
3493 | them (e.g. by ignoring them). Remember that warnings are just that: |
|
|
3494 | warnings, not errors, or proof of bugs. |
|
|
3495 | .SH "VALGRIND" |
|
|
3496 | .IX Header "VALGRIND" |
|
|
3497 | Valgrind has a special section here because it is a popular tool that is |
|
|
3498 | highly useful, but valgrind reports are very hard to interpret. |
|
|
3499 | .PP |
|
|
3500 | If you think you found a bug (memory leak, uninitialised data access etc.) |
|
|
3501 | in libev, then check twice: If valgrind reports something like: |
|
|
3502 | .PP |
|
|
3503 | .Vb 3 |
|
|
3504 | \& ==2274== definitely lost: 0 bytes in 0 blocks. |
|
|
3505 | \& ==2274== possibly lost: 0 bytes in 0 blocks. |
|
|
3506 | \& ==2274== still reachable: 256 bytes in 1 blocks. |
|
|
3507 | .Ve |
|
|
3508 | .PP |
|
|
3509 | then there is no memory leak. Similarly, under some circumstances, |
|
|
3510 | valgrind might report kernel bugs as if it were a bug in libev, or it |
|
|
3511 | might be confused (it is a very good tool, but only a tool). |
|
|
3512 | .PP |
|
|
3513 | If you are unsure about something, feel free to contact the mailing list |
|
|
3514 | with the full valgrind report and an explanation on why you think this is |
|
|
3515 | a bug in libev. However, don't be annoyed when you get a brisk \*(L"this is |
|
|
3516 | no bug\*(R" answer and take the chance of learning how to interpret valgrind |
|
|
3517 | properly. |
|
|
3518 | .PP |
|
|
3519 | If you need, for some reason, empty reports from valgrind for your project |
|
|
3520 | I suggest using suppression lists. |
2314 | .SH "AUTHOR" |
3521 | .SH "AUTHOR" |
2315 | .IX Header "AUTHOR" |
3522 | .IX Header "AUTHOR" |
2316 | Marc Lehmann <libev@schmorp.de>. |
3523 | Marc Lehmann <libev@schmorp.de>. |
|
|
3524 | .SH "POD ERRORS" |
|
|
3525 | .IX Header "POD ERRORS" |
|
|
3526 | Hey! \fBThe above document had some coding errors, which are explained below:\fR |
|
|
3527 | .IP "Around line 3107:" 4 |
|
|
3528 | .IX Item "Around line 3107:" |
|
|
3529 | You forgot a '=back' before '=head2' |