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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 "2008-10-30" "libev-3.48" "libev - high performance 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" |
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144 | .Vb 1 |
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145 | \& #include <ev.h> |
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146 | .Ve |
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147 | .Sh "\s-1EXAMPLE\s0 \s-1PROGRAM\s0" |
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148 | .IX Subsection "EXAMPLE PROGRAM" |
137 | .Vb 2 |
149 | .Vb 2 |
138 | \& /* this is the only header you need */ |
150 | \& // a single header file is required |
139 | \& #include <ev.h> |
151 | \& #include <ev.h> |
140 | .Ve |
152 | \& |
141 | .PP |
153 | \& // every watcher type has its own typedef\*(Aqd struct |
142 | .Vb 3 |
154 | \& // with the name ev_TYPE |
143 | \& /* what follows is a fully working example program */ |
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144 | \& ev_io stdin_watcher; |
155 | \& ev_io stdin_watcher; |
145 | \& ev_timer timeout_watcher; |
156 | \& ev_timer timeout_watcher; |
146 | .Ve |
157 | \& |
147 | .PP |
158 | \& // all watcher callbacks have a similar signature |
148 | .Vb 8 |
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149 | \& /* called when data readable on stdin */ |
159 | \& // this callback is called when data is readable on stdin |
150 | \& static void |
160 | \& static void |
151 | \& stdin_cb (EV_P_ struct ev_io *w, int revents) |
161 | \& stdin_cb (EV_P_ ev_io *w, int revents) |
152 | \& { |
162 | \& { |
153 | \& /* puts ("stdin ready"); */ |
163 | \& puts ("stdin ready"); |
154 | \& ev_io_stop (EV_A_ w); /* just a syntax example */ |
164 | \& // for one\-shot events, one must manually stop the watcher |
155 | \& 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); |
156 | \& } |
170 | \& } |
157 | .Ve |
171 | \& |
158 | .PP |
172 | \& // another callback, this time for a time\-out |
159 | .Vb 6 |
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160 | \& static void |
173 | \& static void |
161 | \& timeout_cb (EV_P_ struct ev_timer *w, int revents) |
174 | \& timeout_cb (EV_P_ ev_timer *w, int revents) |
162 | \& { |
175 | \& { |
163 | \& /* puts ("timeout"); */ |
176 | \& puts ("timeout"); |
164 | \& 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); |
165 | \& } |
179 | \& } |
166 | .Ve |
180 | \& |
167 | .PP |
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168 | .Vb 4 |
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169 | \& int |
181 | \& int |
170 | \& main (void) |
182 | \& main (void) |
171 | \& { |
183 | \& { |
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184 | \& // use the default event loop unless you have special needs |
172 | \& struct ev_loop *loop = ev_default_loop (0); |
185 | \& ev_loop *loop = ev_default_loop (0); |
173 | .Ve |
186 | \& |
174 | .PP |
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175 | .Vb 3 |
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176 | \& /* 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 |
177 | \& 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); |
178 | \& ev_io_start (loop, &stdin_watcher); |
190 | \& ev_io_start (loop, &stdin_watcher); |
179 | .Ve |
191 | \& |
180 | .PP |
192 | \& // initialise a timer watcher, then start it |
181 | .Vb 3 |
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182 | \& /* simple non-repeating 5.5 second timeout */ |
193 | \& // simple non\-repeating 5.5 second timeout |
183 | \& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
194 | \& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
184 | \& ev_timer_start (loop, &timeout_watcher); |
195 | \& ev_timer_start (loop, &timeout_watcher); |
185 | .Ve |
196 | \& |
186 | .PP |
197 | \& // now wait for events to arrive |
187 | .Vb 2 |
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188 | \& /* loop till timeout or data ready */ |
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189 | \& ev_loop (loop, 0); |
198 | \& ev_loop (loop, 0); |
190 | .Ve |
199 | \& |
191 | .PP |
200 | \& // unloop was called, so exit |
192 | .Vb 2 |
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193 | \& return 0; |
201 | \& return 0; |
194 | \& } |
202 | \& } |
195 | .Ve |
203 | .Ve |
196 | .SH "DESCRIPTION" |
204 | .SH "DESCRIPTION" |
197 | .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 |
198 | 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 |
199 | 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 |
200 | these event sources and provide your program with events. |
212 | these event sources and provide your program with events. |
201 | .PP |
213 | .PP |
202 | 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 |
203 | (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 |
204 | communicate events via a callback mechanism. |
216 | communicate events via a callback mechanism. |
205 | .PP |
217 | .PP |
206 | You register interest in certain events by registering so-called \fIevent |
218 | You register interest in certain events by registering so-called \fIevent |
207 | 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 |
208 | 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 |
209 | watcher. |
221 | watcher. |
210 | .SH "FEATURES" |
222 | .Sh "\s-1FEATURES\s0" |
211 | .IX Header "FEATURES" |
223 | .IX Subsection "FEATURES" |
212 | Libev supports select, poll, the linux-specific epoll and the bsd-specific |
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 |
213 | kqueue mechanisms for file descriptor events, relative timers, absolute |
225 | BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port mechanisms |
214 | timers with customised rescheduling, signal events, process status change |
226 | for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR interface |
215 | events (related to \s-1SIGCHLD\s0), and event watchers dealing with the event |
227 | (for \f(CW\*(C`ev_stat\*(C'\fR), relative timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers |
216 | loop mechanism itself (idle, prepare and check watchers). It also is quite |
228 | with customised rescheduling (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals |
217 | fast (see this benchmark comparing |
229 | (\f(CW\*(C`ev_signal\*(C'\fR), process status change events (\f(CW\*(C`ev_child\*(C'\fR), and event |
218 | it to libevent for example). |
230 | watchers dealing with the event loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR, |
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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 |
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232 | file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even limited support for fork events |
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233 | (\f(CW\*(C`ev_fork\*(C'\fR). |
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234 | .PP |
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235 | It also is quite fast (see this |
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236 | benchmark comparing it to libevent |
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237 | for example). |
219 | .SH "CONVENTIONS" |
238 | .Sh "\s-1CONVENTIONS\s0" |
220 | .IX Header "CONVENTIONS" |
239 | .IX Subsection "CONVENTIONS" |
221 | Libev is very configurable. In this manual the default configuration |
240 | Libev is very configurable. In this manual the default (and most common) |
222 | will be described, which supports multiple event loops. For more info |
241 | configuration will be described, which supports multiple event loops. For |
223 | about various configuration options please have a look at the file |
242 | more info about various configuration options please have a look at |
224 | \&\fI\s-1README\s0.embed\fR in the libev distribution. If libev was configured without |
243 | \&\fB\s-1EMBED\s0\fR section in this manual. If libev was configured without support |
225 | support for multiple event loops, then all functions taking an initial |
244 | for multiple event loops, then all functions taking an initial argument of |
226 | argument of name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) |
245 | name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`ev_loop *\*(C'\fR) will not have |
227 | will not have this argument. |
246 | this argument. |
228 | .SH "TIME REPRESENTATION" |
247 | .Sh "\s-1TIME\s0 \s-1REPRESENTATION\s0" |
229 | .IX Header "TIME REPRESENTATION" |
248 | .IX Subsection "TIME REPRESENTATION" |
230 | Libev represents time as a single floating point number, representing the |
249 | Libev represents time as a single floating point number, representing the |
231 | (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 |
232 | 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 |
233 | 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 |
234 | 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 |
235 | it, you should treat it as such. |
254 | it, you should treat it as some floating point 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 system call 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. |
236 | .SH "GLOBAL FUNCTIONS" |
276 | .SH "GLOBAL FUNCTIONS" |
237 | .IX Header "GLOBAL FUNCTIONS" |
277 | .IX Header "GLOBAL FUNCTIONS" |
238 | These functions can be called anytime, even before initialising the |
278 | These functions can be called anytime, even before initialising the |
239 | library in any way. |
279 | library in any way. |
240 | .IP "ev_tstamp ev_time ()" 4 |
280 | .IP "ev_tstamp ev_time ()" 4 |
241 | .IX Item "ev_tstamp ev_time ()" |
281 | .IX Item "ev_tstamp ev_time ()" |
242 | 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 |
243 | \&\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 |
244 | 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 sub-second-resolution \f(CW\*(C`sleep ()\*(C'\fR. |
245 | .IP "int ev_version_major ()" 4 |
290 | .IP "int ev_version_major ()" 4 |
246 | .IX Item "int ev_version_major ()" |
291 | .IX Item "int ev_version_major ()" |
247 | .PD 0 |
292 | .PD 0 |
248 | .IP "int ev_version_minor ()" 4 |
293 | .IP "int ev_version_minor ()" 4 |
249 | .IX Item "int ev_version_minor ()" |
294 | .IX Item "int ev_version_minor ()" |
250 | .PD |
295 | .PD |
251 | 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 |
252 | 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 |
253 | \&\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 |
254 | 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 |
255 | version of the library your program was compiled against. |
300 | version of the library your program was compiled against. |
256 | .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 |
257 | 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, |
258 | as this indicates an incompatible change. Minor versions are usually |
306 | as this indicates an incompatible change. Minor versions are usually |
259 | 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 |
260 | not a problem. |
308 | not a problem. |
261 | .Sp |
309 | .Sp |
262 | 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 |
263 | version: |
311 | version. |
264 | .Sp |
312 | .Sp |
265 | .Vb 3 |
313 | .Vb 3 |
266 | \& assert (("libev version mismatch", |
314 | \& assert (("libev version mismatch", |
267 | \& ev_version_major () == EV_VERSION_MAJOR |
315 | \& ev_version_major () == EV_VERSION_MAJOR |
268 | \& && ev_version_minor () >= EV_VERSION_MINOR)); |
316 | \& && ev_version_minor () >= EV_VERSION_MINOR)); |
269 | .Ve |
317 | .Ve |
270 | .IP "unsigned int ev_supported_backends ()" 4 |
318 | .IP "unsigned int ev_supported_backends ()" 4 |
271 | .IX Item "unsigned int ev_supported_backends ()" |
319 | .IX Item "unsigned int ev_supported_backends ()" |
272 | Return the set of all backends (i.e. their corresponding \f(CW\*(C`EV_BACKEND_*\*(C'\fR |
320 | Return the set of all backends (i.e. their corresponding \f(CW\*(C`EV_BACKEND_*\*(C'\fR |
273 | value) compiled into this binary of libev (independent of their |
321 | value) compiled into this binary of libev (independent of their |
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276 | .Sp |
324 | .Sp |
277 | Example: make sure we have the epoll method, because yeah this is cool and |
325 | Example: make sure we have the epoll method, because yeah this is cool and |
278 | a must have and can we have a torrent of it please!!!11 |
326 | a must have and can we have a torrent of it please!!!11 |
279 | .Sp |
327 | .Sp |
280 | .Vb 2 |
328 | .Vb 2 |
281 | \& assert (("sorry, no epoll, no sex", |
329 | \& assert (("sorry, no epoll, no sex", |
282 | \& ev_supported_backends () & EVBACKEND_EPOLL)); |
330 | \& ev_supported_backends () & EVBACKEND_EPOLL)); |
283 | .Ve |
331 | .Ve |
284 | .IP "unsigned int ev_recommended_backends ()" 4 |
332 | .IP "unsigned int ev_recommended_backends ()" 4 |
285 | .IX Item "unsigned int ev_recommended_backends ()" |
333 | .IX Item "unsigned int ev_recommended_backends ()" |
286 | Return the set of all backends compiled into this binary of libev and also |
334 | Return the set of all backends compiled into this binary of libev and also |
287 | recommended for this platform. This set is often smaller than the one |
335 | recommended for this platform. This set is often smaller than the one |
288 | returned by \f(CW\*(C`ev_supported_backends\*(C'\fR, as for example kqueue is broken on |
336 | returned by \f(CW\*(C`ev_supported_backends\*(C'\fR, as for example kqueue is broken on |
289 | most BSDs and will not be autodetected unless you explicitly request it |
337 | most BSDs and will not be auto-detected unless you explicitly request it |
290 | (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 |
291 | libev will probe for if you specify no backends explicitly. |
339 | libev will probe for if you specify no backends explicitly. |
292 | .IP "unsigned int ev_embeddable_backends ()" 4 |
340 | .IP "unsigned int ev_embeddable_backends ()" 4 |
293 | .IX Item "unsigned int ev_embeddable_backends ()" |
341 | .IX Item "unsigned int ev_embeddable_backends ()" |
294 | 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 |
295 | is the theoretical, all\-platform, value. To find which backends |
343 | is the theoretical, all-platform, value. To find which backends |
296 | 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 |
297 | \&\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 |
298 | recommended ones. |
346 | recommended ones. |
299 | .Sp |
347 | .Sp |
300 | 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. |
301 | .IP "ev_set_allocator (void *(*cb)(void *ptr, size_t size))" 4 |
349 | .IP "ev_set_allocator (void *(*cb)(void *ptr, long size)) [\s-1NOT\s0 \s-1REENTRANT\s0]" 4 |
302 | .IX Item "ev_set_allocator (void *(*cb)(void *ptr, size_t size))" |
350 | .IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT]" |
303 | Sets the allocation function to use (the prototype and semantics are |
351 | Sets the allocation function to use (the prototype is similar \- the |
304 | 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 |
305 | 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 |
306 | 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 |
307 | action. The default is your system realloc function. |
355 | or take some potentially destructive action. |
|
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356 | .Sp |
|
|
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. |
308 | .Sp |
360 | .Sp |
309 | You could override this function in high-availability programs to, say, |
361 | You could override this function in high-availability programs to, say, |
310 | 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, |
311 | 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. |
312 | .Sp |
364 | .Sp |
313 | 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 |
314 | retries: better than mine). |
366 | retries (example requires a standards-compliant \f(CW\*(C`realloc\*(C'\fR). |
315 | .Sp |
367 | .Sp |
316 | .Vb 6 |
368 | .Vb 6 |
317 | \& static void * |
369 | \& static void * |
318 | \& persistent_realloc (void *ptr, size_t size) |
370 | \& persistent_realloc (void *ptr, size_t size) |
319 | \& { |
371 | \& { |
320 | \& for (;;) |
372 | \& for (;;) |
321 | \& { |
373 | \& { |
322 | \& void *newptr = realloc (ptr, size); |
374 | \& void *newptr = realloc (ptr, size); |
323 | .Ve |
375 | \& |
324 | .Sp |
|
|
325 | .Vb 2 |
|
|
326 | \& if (newptr) |
376 | \& if (newptr) |
327 | \& return newptr; |
377 | \& return newptr; |
328 | .Ve |
378 | \& |
329 | .Sp |
|
|
330 | .Vb 3 |
|
|
331 | \& sleep (60); |
379 | \& sleep (60); |
332 | \& } |
380 | \& } |
333 | \& } |
381 | \& } |
334 | .Ve |
382 | \& |
335 | .Sp |
|
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336 | .Vb 2 |
|
|
337 | \& ... |
383 | \& ... |
338 | \& ev_set_allocator (persistent_realloc); |
384 | \& ev_set_allocator (persistent_realloc); |
339 | .Ve |
385 | .Ve |
340 | .IP "ev_set_syserr_cb (void (*cb)(const char *msg));" 4 |
386 | .IP "ev_set_syserr_cb (void (*cb)(const char *msg)); [\s-1NOT\s0 \s-1REENTRANT\s0]" 4 |
341 | .IX Item "ev_set_syserr_cb (void (*cb)(const char *msg));" |
387 | .IX Item "ev_set_syserr_cb (void (*cb)(const char *msg)); [NOT REENTRANT]" |
342 | Set the callback function to call on a retryable syscall error (such |
388 | Set the callback function to call on a retryable system call error (such |
343 | as failed select, poll, epoll_wait). The message is a printable string |
389 | as failed select, poll, epoll_wait). The message is a printable string |
344 | indicating the system call or subsystem causing the problem. If this |
390 | indicating the system call or subsystem causing the problem. If this |
345 | callback is set, then libev will expect it to remedy the sitution, no |
391 | callback is set, then libev will expect it to remedy the situation, no |
346 | matter what, when it returns. That is, libev will generally retry the |
392 | matter what, when it returns. That is, libev will generally retry the |
347 | requested operation, or, if the condition doesn't go away, do bad stuff |
393 | requested operation, or, if the condition doesn't go away, do bad stuff |
348 | (such as abort). |
394 | (such as abort). |
349 | .Sp |
395 | .Sp |
350 | Example: do the same thing as libev does internally: |
396 | Example: This is basically the same thing that libev does internally, too. |
351 | .Sp |
397 | .Sp |
352 | .Vb 6 |
398 | .Vb 6 |
353 | \& static void |
399 | \& static void |
354 | \& fatal_error (const char *msg) |
400 | \& fatal_error (const char *msg) |
355 | \& { |
401 | \& { |
356 | \& perror (msg); |
402 | \& perror (msg); |
357 | \& abort (); |
403 | \& abort (); |
358 | \& } |
404 | \& } |
359 | .Ve |
405 | \& |
360 | .Sp |
|
|
361 | .Vb 2 |
|
|
362 | \& ... |
406 | \& ... |
363 | \& ev_set_syserr_cb (fatal_error); |
407 | \& ev_set_syserr_cb (fatal_error); |
364 | .Ve |
408 | .Ve |
365 | .SH "FUNCTIONS CONTROLLING THE EVENT LOOP" |
409 | .SH "FUNCTIONS CONTROLLING THE EVENT LOOP" |
366 | .IX Header "FUNCTIONS CONTROLLING THE EVENT LOOP" |
410 | .IX Header "FUNCTIONS CONTROLLING THE EVENT LOOP" |
367 | 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 \f(CW\*(C`struct\*(C'\fR |
368 | types of such loops, the \fIdefault\fR loop, which supports signals and child |
412 | is \fInot\fR optional in this case, as there is also an \f(CW\*(C`ev_loop\*(C'\fR |
369 | events, and dynamically created loops which do not. |
413 | \&\fIfunction\fR). |
370 | .PP |
414 | .PP |
371 | If you use threads, a common model is to run the default event loop |
415 | The library knows two types of such loops, the \fIdefault\fR loop, which |
372 | in your main thread (or in a separate thread) and for each thread you |
416 | supports signals and child events, and dynamically created loops which do |
373 | create, you also create another event loop. Libev itself does no locking |
417 | not. |
374 | whatsoever, so if you mix calls to the same event loop in different |
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375 | threads, make sure you lock (this is usually a bad idea, though, even if |
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376 | done correctly, because it's hideous and inefficient). |
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377 | .IP "struct ev_loop *ev_default_loop (unsigned int flags)" 4 |
418 | .IP "struct ev_loop *ev_default_loop (unsigned int flags)" 4 |
378 | .IX Item "struct ev_loop *ev_default_loop (unsigned int flags)" |
419 | .IX Item "struct ev_loop *ev_default_loop (unsigned int flags)" |
379 | This will initialise the default event loop if it hasn't been initialised |
420 | This will initialise the default event loop if it hasn't been initialised |
380 | yet and return it. If the default loop could not be initialised, returns |
421 | yet and return it. If the default loop could not be initialised, returns |
381 | false. If it already was initialised it simply returns it (and ignores the |
422 | false. If it already was initialised it simply returns it (and ignores the |
382 | flags. If that is troubling you, check \f(CW\*(C`ev_backend ()\*(C'\fR afterwards). |
423 | flags. If that is troubling you, check \f(CW\*(C`ev_backend ()\*(C'\fR afterwards). |
383 | .Sp |
424 | .Sp |
384 | If you don't know what event loop to use, use the one returned from this |
425 | If you don't know what event loop to use, use the one returned from this |
385 | function. |
426 | function. |
|
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427 | .Sp |
|
|
428 | Note that this function is \fInot\fR thread-safe, so if you want to use it |
|
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429 | from multiple threads, you have to lock (note also that this is unlikely, |
|
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430 | as loops cannot be shared easily between threads anyway). |
|
|
431 | .Sp |
|
|
432 | The default loop is the only loop that can handle \f(CW\*(C`ev_signal\*(C'\fR and |
|
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433 | \&\f(CW\*(C`ev_child\*(C'\fR watchers, and to do this, it always registers a handler |
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434 | for \f(CW\*(C`SIGCHLD\*(C'\fR. If this is a problem for your application you can either |
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435 | create a dynamic loop with \f(CW\*(C`ev_loop_new\*(C'\fR that doesn't do that, or you |
|
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436 | can simply overwrite the \f(CW\*(C`SIGCHLD\*(C'\fR signal handler \fIafter\fR calling |
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437 | \&\f(CW\*(C`ev_default_init\*(C'\fR. |
386 | .Sp |
438 | .Sp |
387 | The flags argument can be used to specify special behaviour or specific |
439 | The flags argument can be used to specify special behaviour or specific |
388 | backends to use, and is usually specified as \f(CW0\fR (or \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). |
440 | backends to use, and is usually specified as \f(CW0\fR (or \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). |
389 | .Sp |
441 | .Sp |
390 | The following flags are supported: |
442 | The following flags are supported: |
… | |
… | |
395 | The default flags value. Use this if you have no clue (it's the right |
447 | The default flags value. Use this if you have no clue (it's the right |
396 | thing, believe me). |
448 | thing, believe me). |
397 | .ie n .IP """EVFLAG_NOENV""" 4 |
449 | .ie n .IP """EVFLAG_NOENV""" 4 |
398 | .el .IP "\f(CWEVFLAG_NOENV\fR" 4 |
450 | .el .IP "\f(CWEVFLAG_NOENV\fR" 4 |
399 | .IX Item "EVFLAG_NOENV" |
451 | .IX Item "EVFLAG_NOENV" |
400 | If this flag bit is ored into the flag value (or the program runs setuid |
452 | If this flag bit is or'ed into the flag value (or the program runs setuid |
401 | or setgid) then libev will \fInot\fR look at the environment variable |
453 | or setgid) then libev will \fInot\fR look at the environment variable |
402 | \&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will |
454 | \&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will |
403 | override the flags completely if it is found in the environment. This is |
455 | override the flags completely if it is found in the environment. This is |
404 | useful to try out specific backends to test their performance, or to work |
456 | useful to try out specific backends to test their performance, or to work |
405 | around bugs. |
457 | around bugs. |
|
|
458 | .ie n .IP """EVFLAG_FORKCHECK""" 4 |
|
|
459 | .el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4 |
|
|
460 | .IX Item "EVFLAG_FORKCHECK" |
|
|
461 | 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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462 | a fork, you can also make libev check for a fork in each iteration by |
|
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463 | enabling this flag. |
|
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464 | .Sp |
|
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465 | This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop, |
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466 | and thus this might slow down your event loop if you do a lot of loop |
|
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467 | iterations and little real work, but is usually not noticeable (on my |
|
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468 | GNU/Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence |
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469 | without a system call and thus \fIvery\fR fast, but my GNU/Linux system also has |
|
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470 | \&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster). |
|
|
471 | .Sp |
|
|
472 | The big advantage of this flag is that you can forget about fork (and |
|
|
473 | forget about forgetting to tell libev about forking) when you use this |
|
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474 | flag. |
|
|
475 | .Sp |
|
|
476 | This flag setting cannot be overridden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR |
|
|
477 | environment variable. |
406 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
478 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
407 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
479 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
408 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
480 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
409 | This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
481 | This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
410 | libev tries to roll its own fd_set with no limits on the number of fds, |
482 | libev tries to roll its own fd_set with no limits on the number of fds, |
411 | but if that fails, expect a fairly low limit on the number of fds when |
483 | but if that fails, expect a fairly low limit on the number of fds when |
412 | using this backend. It doesn't scale too well (O(highest_fd)), but its usually |
484 | using this backend. It doesn't scale too well (O(highest_fd)), but its |
413 | the fastest backend for a low number of fds. |
485 | usually the fastest backend for a low number of (low-numbered :) fds. |
|
|
486 | .Sp |
|
|
487 | To get good performance out of this backend you need a high amount of |
|
|
488 | parallelism (most of the file descriptors should be busy). If you are |
|
|
489 | writing a server, you should \f(CW\*(C`accept ()\*(C'\fR in a loop to accept as many |
|
|
490 | connections as possible during one iteration. You might also want to have |
|
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491 | a look at \f(CW\*(C`ev_set_io_collect_interval ()\*(C'\fR to increase the amount of |
|
|
492 | readiness notifications you get per iteration. |
|
|
493 | .Sp |
|
|
494 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR to the \f(CW\*(C`readfds\*(C'\fR set and \f(CW\*(C`EV_WRITE\*(C'\fR to the |
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495 | \&\f(CW\*(C`writefds\*(C'\fR set (and to work around Microsoft Windows bugs, also onto the |
|
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496 | \&\f(CW\*(C`exceptfds\*(C'\fR set on that platform). |
414 | .ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4 |
497 | .ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4 |
415 | .el .IP "\f(CWEVBACKEND_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4 |
498 | .el .IP "\f(CWEVBACKEND_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4 |
416 | .IX Item "EVBACKEND_POLL (value 2, poll backend, available everywhere except on windows)" |
499 | .IX Item "EVBACKEND_POLL (value 2, poll backend, available everywhere except on windows)" |
417 | And this is your standard \fIpoll\fR\|(2) backend. It's more complicated than |
500 | And this is your standard \fIpoll\fR\|(2) backend. It's more complicated |
418 | select, but handles sparse fds better and has no artificial limit on the |
501 | than select, but handles sparse fds better and has no artificial |
419 | number of fds you can use (except it will slow down considerably with a |
502 | limit on the number of fds you can use (except it will slow down |
420 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds). |
503 | considerably with a lot of inactive fds). It scales similarly to select, |
|
|
504 | i.e. O(total_fds). See the entry for \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR, above, for |
|
|
505 | performance tips. |
|
|
506 | .Sp |
|
|
507 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR to \f(CW\*(C`POLLIN | POLLERR | POLLHUP\*(C'\fR, and |
|
|
508 | \&\f(CW\*(C`EV_WRITE\*(C'\fR to \f(CW\*(C`POLLOUT | POLLERR | POLLHUP\*(C'\fR. |
421 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
509 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
422 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
510 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
423 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
511 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
424 | For few fds, this backend is a bit little slower than poll and select, |
512 | For few fds, this backend is a bit little slower than poll and select, |
425 | but it scales phenomenally better. While poll and select usually scale like |
513 | but it scales phenomenally better. While poll and select usually scale |
426 | O(total_fds) where n is the total number of fds (or the highest fd), epoll scales |
514 | like O(total_fds) where n is the total number of fds (or the highest fd), |
427 | either O(1) or O(active_fds). |
515 | epoll scales either O(1) or O(active_fds). |
428 | .Sp |
516 | .Sp |
|
|
517 | The epoll mechanism deserves honorable mention as the most misdesigned |
|
|
518 | of the more advanced event mechanisms: mere annoyances include silently |
|
|
519 | dropping file descriptors, requiring a system call per change per file |
|
|
520 | descriptor (and unnecessary guessing of parameters), problems with dup and |
|
|
521 | so on. The biggest issue is fork races, however \- if a program forks then |
|
|
522 | \&\fIboth\fR parent and child process have to recreate the epoll set, which can |
|
|
523 | take considerable time (one syscall per file descriptor) and is of course |
|
|
524 | hard to detect. |
|
|
525 | .Sp |
|
|
526 | Epoll is also notoriously buggy \- embedding epoll fds \fIshould\fR work, but |
|
|
527 | of course \fIdoesn't\fR, and epoll just loves to report events for totally |
|
|
528 | \&\fIdifferent\fR file descriptors (even already closed ones, so one cannot |
|
|
529 | even remove them from the set) than registered in the set (especially |
|
|
530 | on \s-1SMP\s0 systems). Libev tries to counter these spurious notifications by |
|
|
531 | employing an additional generation counter and comparing that against the |
|
|
532 | events to filter out spurious ones, recreating the set when required. |
|
|
533 | .Sp |
429 | While stopping and starting an I/O watcher in the same iteration will |
534 | While stopping, setting and starting an I/O watcher in the same iteration |
430 | result in some caching, there is still a syscall per such incident |
535 | will result in some caching, there is still a system call per such |
431 | (because the fd could point to a different file description now), so its |
536 | incident (because the same \fIfile descriptor\fR could point to a different |
432 | best to avoid that. Also, \fIdup()\fRed file descriptors might not work very |
537 | \&\fIfile description\fR now), so its best to avoid that. Also, \f(CW\*(C`dup ()\*(C'\fR'ed |
433 | well if you register events for both fds. |
538 | file descriptors might not work very well if you register events for both |
|
|
539 | file descriptors. |
434 | .Sp |
540 | .Sp |
435 | Please note that epoll sometimes generates spurious notifications, so you |
541 | Best performance from this backend is achieved by not unregistering all |
436 | need to use non-blocking I/O or other means to avoid blocking when no data |
542 | watchers for a file descriptor until it has been closed, if possible, |
437 | (or space) is available. |
543 | i.e. keep at least one watcher active per fd at all times. Stopping and |
|
|
544 | starting a watcher (without re-setting it) also usually doesn't cause |
|
|
545 | extra overhead. A fork can both result in spurious notifications as well |
|
|
546 | as in libev having to destroy and recreate the epoll object, which can |
|
|
547 | take considerable time and thus should be avoided. |
|
|
548 | .Sp |
|
|
549 | While nominally embeddable in other event loops, this feature is broken in |
|
|
550 | all kernel versions tested so far. |
|
|
551 | .Sp |
|
|
552 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
|
|
553 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
438 | .ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 |
554 | .ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 |
439 | .el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 |
555 | .el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 |
440 | .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" |
556 | .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" |
441 | Kqueue deserves special mention, as at the time of this writing, it |
557 | Kqueue deserves special mention, as at the time of this writing, it |
442 | was broken on all BSDs except NetBSD (usually it doesn't work with |
558 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
443 | anything but sockets and pipes, except on Darwin, where of course its |
559 | with anything but sockets and pipes, except on Darwin, where of course |
444 | completely useless). For this reason its not being \*(L"autodetected\*(R" |
560 | it's completely useless). Unlike epoll, however, whose brokenness |
|
|
561 | is by design, these kqueue bugs can (and eventually will) be fixed |
|
|
562 | without \s-1API\s0 changes to existing programs. For this reason it's not being |
445 | unless you explicitly specify it explicitly in the flags (i.e. using |
563 | \&\*(L"auto-detected\*(R" unless you explicitly specify it in the flags (i.e. using |
446 | \&\f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR). |
564 | \&\f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR) or libev was compiled on a known-to-be-good (\-enough) |
|
|
565 | system like NetBSD. |
|
|
566 | .Sp |
|
|
567 | You still can embed kqueue into a normal poll or select backend and use it |
|
|
568 | only for sockets (after having made sure that sockets work with kqueue on |
|
|
569 | the target platform). See \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
447 | .Sp |
570 | .Sp |
448 | It scales in the same way as the epoll backend, but the interface to the |
571 | It scales in the same way as the epoll backend, but the interface to the |
449 | kernel is more efficient (which says nothing about its actual speed, of |
572 | kernel is more efficient (which says nothing about its actual speed, of |
450 | course). While starting and stopping an I/O watcher does not cause an |
573 | course). While stopping, setting and starting an I/O watcher does never |
451 | extra syscall as with epoll, it still adds up to four event changes per |
574 | cause an extra system call as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to |
452 | incident, so its best to avoid that. |
575 | two event changes per incident. Support for \f(CW\*(C`fork ()\*(C'\fR is very bad (but |
|
|
576 | sane, unlike epoll) and it drops fds silently in similarly hard-to-detect |
|
|
577 | cases |
|
|
578 | .Sp |
|
|
579 | This backend usually performs well under most conditions. |
|
|
580 | .Sp |
|
|
581 | While nominally embeddable in other event loops, this doesn't work |
|
|
582 | everywhere, so you might need to test for this. And since it is broken |
|
|
583 | almost everywhere, you should only use it when you have a lot of sockets |
|
|
584 | (for which it usually works), by embedding it into another event loop |
|
|
585 | (e.g. \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR) and, did I mention it, |
|
|
586 | using it only for sockets. |
|
|
587 | .Sp |
|
|
588 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR into an \f(CW\*(C`EVFILT_READ\*(C'\fR kevent with |
|
|
589 | \&\f(CW\*(C`NOTE_EOF\*(C'\fR, and \f(CW\*(C`EV_WRITE\*(C'\fR into an \f(CW\*(C`EVFILT_WRITE\*(C'\fR kevent with |
|
|
590 | \&\f(CW\*(C`NOTE_EOF\*(C'\fR. |
453 | .ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 |
591 | .ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 |
454 | .el .IP "\f(CWEVBACKEND_DEVPOLL\fR (value 16, Solaris 8)" 4 |
592 | .el .IP "\f(CWEVBACKEND_DEVPOLL\fR (value 16, Solaris 8)" 4 |
455 | .IX Item "EVBACKEND_DEVPOLL (value 16, Solaris 8)" |
593 | .IX Item "EVBACKEND_DEVPOLL (value 16, Solaris 8)" |
456 | This is not implemented yet (and might never be). |
594 | This is not implemented yet (and might never be, unless you send me an |
|
|
595 | implementation). According to reports, \f(CW\*(C`/dev/poll\*(C'\fR only supports sockets |
|
|
596 | and is not embeddable, which would limit the usefulness of this backend |
|
|
597 | immensely. |
457 | .ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 |
598 | .ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 |
458 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
599 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
459 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
600 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
460 | This uses the Solaris 10 port mechanism. As with everything on Solaris, |
601 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
461 | it's really slow, but it still scales very well (O(active_fds)). |
602 | it's really slow, but it still scales very well (O(active_fds)). |
462 | .Sp |
603 | .Sp |
463 | Please note that solaris ports can result in a lot of spurious |
604 | Please note that Solaris event ports can deliver a lot of spurious |
464 | notifications, so you need to use non-blocking I/O or other means to avoid |
605 | notifications, so you need to use non-blocking I/O or other means to avoid |
465 | blocking when no data (or space) is available. |
606 | blocking when no data (or space) is available. |
|
|
607 | .Sp |
|
|
608 | While this backend scales well, it requires one system call per active |
|
|
609 | file descriptor per loop iteration. For small and medium numbers of file |
|
|
610 | descriptors a \*(L"slow\*(R" \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR backend |
|
|
611 | might perform better. |
|
|
612 | .Sp |
|
|
613 | On the positive side, with the exception of the spurious readiness |
|
|
614 | notifications, this backend actually performed fully to specification |
|
|
615 | in all tests and is fully embeddable, which is a rare feat among the |
|
|
616 | OS-specific backends (I vastly prefer correctness over speed hacks). |
|
|
617 | .Sp |
|
|
618 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
|
|
619 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
466 | .ie n .IP """EVBACKEND_ALL""" 4 |
620 | .ie n .IP """EVBACKEND_ALL""" 4 |
467 | .el .IP "\f(CWEVBACKEND_ALL\fR" 4 |
621 | .el .IP "\f(CWEVBACKEND_ALL\fR" 4 |
468 | .IX Item "EVBACKEND_ALL" |
622 | .IX Item "EVBACKEND_ALL" |
469 | Try all backends (even potentially broken ones that wouldn't be tried |
623 | Try all backends (even potentially broken ones that wouldn't be tried |
470 | with \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). Since this is a mask, you can do stuff such as |
624 | with \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). Since this is a mask, you can do stuff such as |
471 | \&\f(CW\*(C`EVBACKEND_ALL & ~EVBACKEND_KQUEUE\*(C'\fR. |
625 | \&\f(CW\*(C`EVBACKEND_ALL & ~EVBACKEND_KQUEUE\*(C'\fR. |
|
|
626 | .Sp |
|
|
627 | It is definitely not recommended to use this flag. |
472 | .RE |
628 | .RE |
473 | .RS 4 |
629 | .RS 4 |
474 | .Sp |
630 | .Sp |
475 | If one or more of these are ored into the flags value, then only these |
631 | If one or more of these are or'ed into the flags value, then only these |
476 | backends will be tried (in the reverse order as given here). If none are |
632 | backends will be tried (in the reverse order as listed here). If none are |
477 | specified, most compiled-in backend will be tried, usually in reverse |
633 | specified, all backends in \f(CW\*(C`ev_recommended_backends ()\*(C'\fR will be tried. |
478 | order of their flag values :) |
|
|
479 | .Sp |
634 | .Sp |
480 | The most typical usage is like this: |
635 | Example: This is the most typical usage. |
481 | .Sp |
636 | .Sp |
482 | .Vb 2 |
637 | .Vb 2 |
483 | \& if (!ev_default_loop (0)) |
638 | \& if (!ev_default_loop (0)) |
484 | \& fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
639 | \& fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
485 | .Ve |
640 | .Ve |
486 | .Sp |
641 | .Sp |
487 | Restrict libev to the select and poll backends, and do not allow |
642 | Example: Restrict libev to the select and poll backends, and do not allow |
488 | environment settings to be taken into account: |
643 | environment settings to be taken into account: |
489 | .Sp |
644 | .Sp |
490 | .Vb 1 |
645 | .Vb 1 |
491 | \& ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
646 | \& ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
492 | .Ve |
647 | .Ve |
493 | .Sp |
648 | .Sp |
494 | Use whatever libev has to offer, but make sure that kqueue is used if |
649 | Example: Use whatever libev has to offer, but make sure that kqueue is |
495 | available (warning, breaks stuff, best use only with your own private |
650 | used if available (warning, breaks stuff, best use only with your own |
496 | event loop and only if you know the \s-1OS\s0 supports your types of fds): |
651 | private event loop and only if you know the \s-1OS\s0 supports your types of |
|
|
652 | fds): |
497 | .Sp |
653 | .Sp |
498 | .Vb 1 |
654 | .Vb 1 |
499 | \& ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
655 | \& ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
500 | .Ve |
656 | .Ve |
501 | .RE |
657 | .RE |
502 | .IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4 |
658 | .IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4 |
503 | .IX Item "struct ev_loop *ev_loop_new (unsigned int flags)" |
659 | .IX Item "struct ev_loop *ev_loop_new (unsigned int flags)" |
504 | Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is |
660 | Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is |
505 | always distinct from the default loop. Unlike the default loop, it cannot |
661 | always distinct from the default loop. Unlike the default loop, it cannot |
506 | handle signal and child watchers, and attempts to do so will be greeted by |
662 | handle signal and child watchers, and attempts to do so will be greeted by |
507 | undefined behaviour (or a failed assertion if assertions are enabled). |
663 | undefined behaviour (or a failed assertion if assertions are enabled). |
508 | .Sp |
664 | .Sp |
|
|
665 | Note that this function \fIis\fR thread-safe, and the recommended way to use |
|
|
666 | libev with threads is indeed to create one loop per thread, and using the |
|
|
667 | default loop in the \*(L"main\*(R" or \*(L"initial\*(R" thread. |
|
|
668 | .Sp |
509 | Example: try to create a event loop that uses epoll and nothing else. |
669 | Example: Try to create a event loop that uses epoll and nothing else. |
510 | .Sp |
670 | .Sp |
511 | .Vb 3 |
671 | .Vb 3 |
512 | \& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
672 | \& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
513 | \& if (!epoller) |
673 | \& if (!epoller) |
514 | \& fatal ("no epoll found here, maybe it hides under your chair"); |
674 | \& fatal ("no epoll found here, maybe it hides under your chair"); |
515 | .Ve |
675 | .Ve |
516 | .IP "ev_default_destroy ()" 4 |
676 | .IP "ev_default_destroy ()" 4 |
517 | .IX Item "ev_default_destroy ()" |
677 | .IX Item "ev_default_destroy ()" |
518 | Destroys the default loop again (frees all memory and kernel state |
678 | Destroys the default loop again (frees all memory and kernel state |
519 | etc.). None of the active event watchers will be stopped in the normal |
679 | etc.). None of the active event watchers will be stopped in the normal |
520 | sense, so e.g. \f(CW\*(C`ev_is_active\*(C'\fR might still return true. It is your |
680 | sense, so e.g. \f(CW\*(C`ev_is_active\*(C'\fR might still return true. It is your |
521 | responsibility to either stop all watchers cleanly yoursef \fIbefore\fR |
681 | responsibility to either stop all watchers cleanly yourself \fIbefore\fR |
522 | calling this function, or cope with the fact afterwards (which is usually |
682 | calling this function, or cope with the fact afterwards (which is usually |
523 | the easiest thing, youc na just ignore the watchers and/or \f(CW\*(C`free ()\*(C'\fR them |
683 | the easiest thing, you can just ignore the watchers and/or \f(CW\*(C`free ()\*(C'\fR them |
524 | for example). |
684 | for example). |
|
|
685 | .Sp |
|
|
686 | Note that certain global state, such as signal state (and installed signal |
|
|
687 | handlers), will not be freed by this function, and related watchers (such |
|
|
688 | as signal and child watchers) would need to be stopped manually. |
|
|
689 | .Sp |
|
|
690 | In general it is not advisable to call this function except in the |
|
|
691 | rare occasion where you really need to free e.g. the signal handling |
|
|
692 | pipe fds. If you need dynamically allocated loops it is better to use |
|
|
693 | \&\f(CW\*(C`ev_loop_new\*(C'\fR and \f(CW\*(C`ev_loop_destroy\*(C'\fR). |
525 | .IP "ev_loop_destroy (loop)" 4 |
694 | .IP "ev_loop_destroy (loop)" 4 |
526 | .IX Item "ev_loop_destroy (loop)" |
695 | .IX Item "ev_loop_destroy (loop)" |
527 | Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an |
696 | Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an |
528 | earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR. |
697 | earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR. |
529 | .IP "ev_default_fork ()" 4 |
698 | .IP "ev_default_fork ()" 4 |
530 | .IX Item "ev_default_fork ()" |
699 | .IX Item "ev_default_fork ()" |
|
|
700 | This function sets a flag that causes subsequent \f(CW\*(C`ev_loop\*(C'\fR iterations |
531 | This function reinitialises the kernel state for backends that have |
701 | to reinitialise the kernel state for backends that have one. Despite the |
532 | one. Despite the name, you can call it anytime, but it makes most sense |
702 | name, you can call it anytime, but it makes most sense after forking, in |
533 | after forking, in either the parent or child process (or both, but that |
703 | the child process (or both child and parent, but that again makes little |
534 | again makes little sense). |
704 | sense). You \fImust\fR call it in the child before using any of the libev |
|
|
705 | functions, and it will only take effect at the next \f(CW\*(C`ev_loop\*(C'\fR iteration. |
535 | .Sp |
706 | .Sp |
536 | You \fImust\fR call this function in the child process after forking if and |
707 | On the other hand, you only need to call this function in the child |
537 | only if you want to use the event library in both processes. If you just |
708 | process if and only if you want to use the event library in the child. If |
538 | fork+exec, you don't have to call it. |
709 | you just fork+exec, you don't have to call it at all. |
539 | .Sp |
710 | .Sp |
540 | The function itself is quite fast and it's usually not a problem to call |
711 | The function itself is quite fast and it's usually not a problem to call |
541 | it just in case after a fork. To make this easy, the function will fit in |
712 | it just in case after a fork. To make this easy, the function will fit in |
542 | quite nicely into a call to \f(CW\*(C`pthread_atfork\*(C'\fR: |
713 | quite nicely into a call to \f(CW\*(C`pthread_atfork\*(C'\fR: |
543 | .Sp |
714 | .Sp |
544 | .Vb 1 |
715 | .Vb 1 |
545 | \& pthread_atfork (0, 0, ev_default_fork); |
716 | \& pthread_atfork (0, 0, ev_default_fork); |
546 | .Ve |
717 | .Ve |
547 | .Sp |
|
|
548 | At the moment, \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and \f(CW\*(C`EVBACKEND_POLL\*(C'\fR are safe to use |
|
|
549 | without calling this function, so if you force one of those backends you |
|
|
550 | do not need to care. |
|
|
551 | .IP "ev_loop_fork (loop)" 4 |
718 | .IP "ev_loop_fork (loop)" 4 |
552 | .IX Item "ev_loop_fork (loop)" |
719 | .IX Item "ev_loop_fork (loop)" |
553 | Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by |
720 | Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by |
554 | \&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop |
721 | \&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop |
555 | after fork, and how you do this is entirely your own problem. |
722 | after fork that you want to re-use in the child, and how you do this is |
|
|
723 | entirely your own problem. |
|
|
724 | .IP "int ev_is_default_loop (loop)" 4 |
|
|
725 | .IX Item "int ev_is_default_loop (loop)" |
|
|
726 | Returns true when the given loop is, in fact, the default loop, and false |
|
|
727 | otherwise. |
|
|
728 | .IP "unsigned int ev_loop_count (loop)" 4 |
|
|
729 | .IX Item "unsigned int ev_loop_count (loop)" |
|
|
730 | Returns the count of loop iterations for the loop, which is identical to |
|
|
731 | the number of times libev did poll for new events. It starts at \f(CW0\fR and |
|
|
732 | happily wraps around with enough iterations. |
|
|
733 | .Sp |
|
|
734 | This value can sometimes be useful as a generation counter of sorts (it |
|
|
735 | \&\*(L"ticks\*(R" the number of loop iterations), as it roughly corresponds with |
|
|
736 | \&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls. |
556 | .IP "unsigned int ev_backend (loop)" 4 |
737 | .IP "unsigned int ev_backend (loop)" 4 |
557 | .IX Item "unsigned int ev_backend (loop)" |
738 | .IX Item "unsigned int ev_backend (loop)" |
558 | Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in |
739 | Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in |
559 | use. |
740 | use. |
560 | .IP "ev_tstamp ev_now (loop)" 4 |
741 | .IP "ev_tstamp ev_now (loop)" 4 |
561 | .IX Item "ev_tstamp ev_now (loop)" |
742 | .IX Item "ev_tstamp ev_now (loop)" |
562 | Returns the current \*(L"event loop time\*(R", which is the time the event loop |
743 | Returns the current \*(L"event loop time\*(R", which is the time the event loop |
563 | received events and started processing them. This timestamp does not |
744 | received events and started processing them. This timestamp does not |
564 | change as long as callbacks are being processed, and this is also the base |
745 | change as long as callbacks are being processed, and this is also the base |
565 | time used for relative timers. You can treat it as the timestamp of the |
746 | time used for relative timers. You can treat it as the timestamp of the |
566 | event occuring (or more correctly, libev finding out about it). |
747 | event occurring (or more correctly, libev finding out about it). |
|
|
748 | .IP "ev_now_update (loop)" 4 |
|
|
749 | .IX Item "ev_now_update (loop)" |
|
|
750 | Establishes the current time by querying the kernel, updating the time |
|
|
751 | returned by \f(CW\*(C`ev_now ()\*(C'\fR in the progress. This is a costly operation and |
|
|
752 | is usually done automatically within \f(CW\*(C`ev_loop ()\*(C'\fR. |
|
|
753 | .Sp |
|
|
754 | This function is rarely useful, but when some event callback runs for a |
|
|
755 | very long time without entering the event loop, updating libev's idea of |
|
|
756 | the current time is a good idea. |
|
|
757 | .Sp |
|
|
758 | See also \*(L"The special problem of time updates\*(R" in the \f(CW\*(C`ev_timer\*(C'\fR section. |
567 | .IP "ev_loop (loop, int flags)" 4 |
759 | .IP "ev_loop (loop, int flags)" 4 |
568 | .IX Item "ev_loop (loop, int flags)" |
760 | .IX Item "ev_loop (loop, int flags)" |
569 | Finally, this is it, the event handler. This function usually is called |
761 | Finally, this is it, the event handler. This function usually is called |
570 | after you initialised all your watchers and you want to start handling |
762 | after you initialised all your watchers and you want to start handling |
571 | events. |
763 | events. |
… | |
… | |
573 | If the flags argument is specified as \f(CW0\fR, it will not return until |
765 | If the flags argument is specified as \f(CW0\fR, it will not return until |
574 | either no event watchers are active anymore or \f(CW\*(C`ev_unloop\*(C'\fR was called. |
766 | either no event watchers are active anymore or \f(CW\*(C`ev_unloop\*(C'\fR was called. |
575 | .Sp |
767 | .Sp |
576 | Please note that an explicit \f(CW\*(C`ev_unloop\*(C'\fR is usually better than |
768 | Please note that an explicit \f(CW\*(C`ev_unloop\*(C'\fR is usually better than |
577 | relying on all watchers to be stopped when deciding when a program has |
769 | relying on all watchers to be stopped when deciding when a program has |
578 | finished (especially in interactive programs), but having a program that |
770 | finished (especially in interactive programs), but having a program |
579 | automatically loops as long as it has to and no longer by virtue of |
771 | that automatically loops as long as it has to and no longer by virtue |
580 | relying on its watchers stopping correctly is a thing of beauty. |
772 | of relying on its watchers stopping correctly, that is truly a thing of |
|
|
773 | beauty. |
581 | .Sp |
774 | .Sp |
582 | A flags value of \f(CW\*(C`EVLOOP_NONBLOCK\*(C'\fR will look for new events, will handle |
775 | A flags value of \f(CW\*(C`EVLOOP_NONBLOCK\*(C'\fR will look for new events, will handle |
583 | those events and any outstanding ones, but will not block your process in |
776 | those events and any already outstanding ones, but will not block your |
584 | case there are no events and will return after one iteration of the loop. |
777 | process in case there are no events and will return after one iteration of |
|
|
778 | the loop. |
585 | .Sp |
779 | .Sp |
586 | A flags value of \f(CW\*(C`EVLOOP_ONESHOT\*(C'\fR will look for new events (waiting if |
780 | A flags value of \f(CW\*(C`EVLOOP_ONESHOT\*(C'\fR will look for new events (waiting if |
587 | neccessary) and will handle those and any outstanding ones. It will block |
781 | necessary) and will handle those and any already outstanding ones. It |
588 | your process until at least one new event arrives, and will return after |
782 | will block your process until at least one new event arrives (which could |
589 | one iteration of the loop. This is useful if you are waiting for some |
783 | be an event internal to libev itself, so there is no guarantee that a |
590 | external event in conjunction with something not expressible using other |
784 | user-registered callback will be called), and will return after one |
|
|
785 | iteration of the loop. |
|
|
786 | .Sp |
|
|
787 | This is useful if you are waiting for some external event in conjunction |
|
|
788 | with something not expressible using other libev watchers (i.e. "roll your |
591 | libev watchers. However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is |
789 | own \f(CW\*(C`ev_loop\*(C'\fR"). However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is |
592 | usually a better approach for this kind of thing. |
790 | usually a better approach for this kind of thing. |
593 | .Sp |
791 | .Sp |
594 | Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does: |
792 | Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does: |
595 | .Sp |
793 | .Sp |
596 | .Vb 18 |
794 | .Vb 10 |
597 | \& * If there are no active watchers (reference count is zero), return. |
795 | \& \- Before the first iteration, call any pending watchers. |
598 | \& - Queue prepare watchers and then call all outstanding watchers. |
796 | \& * If EVFLAG_FORKCHECK was used, check for a fork. |
|
|
797 | \& \- If a fork was detected (by any means), queue and call all fork watchers. |
|
|
798 | \& \- Queue and call all prepare watchers. |
599 | \& - If we have been forked, recreate the kernel state. |
799 | \& \- If we have been forked, detach and recreate the kernel state |
|
|
800 | \& as to not disturb the other process. |
600 | \& - Update the kernel state with all outstanding changes. |
801 | \& \- Update the kernel state with all outstanding changes. |
601 | \& - Update the "event loop time". |
802 | \& \- Update the "event loop time" (ev_now ()). |
602 | \& - Calculate for how long to block. |
803 | \& \- Calculate for how long to sleep or block, if at all |
|
|
804 | \& (active idle watchers, EVLOOP_NONBLOCK or not having |
|
|
805 | \& any active watchers at all will result in not sleeping). |
|
|
806 | \& \- Sleep if the I/O and timer collect interval say so. |
603 | \& - Block the process, waiting for any events. |
807 | \& \- Block the process, waiting for any events. |
604 | \& - Queue all outstanding I/O (fd) events. |
808 | \& \- Queue all outstanding I/O (fd) events. |
605 | \& - Update the "event loop time" and do time jump handling. |
809 | \& \- Update the "event loop time" (ev_now ()), and do time jump adjustments. |
606 | \& - Queue all outstanding timers. |
810 | \& \- Queue all expired timers. |
607 | \& - Queue all outstanding periodics. |
811 | \& \- Queue all expired periodics. |
608 | \& - If no events are pending now, queue all idle watchers. |
812 | \& \- Unless any events are pending now, queue all idle watchers. |
609 | \& - Queue all check watchers. |
813 | \& \- Queue all check watchers. |
610 | \& - Call all queued watchers in reverse order (i.e. check watchers first). |
814 | \& \- Call all queued watchers in reverse order (i.e. check watchers first). |
611 | \& Signals and child watchers are implemented as I/O watchers, and will |
815 | \& Signals and child watchers are implemented as I/O watchers, and will |
612 | \& be handled here by queueing them when their watcher gets executed. |
816 | \& be handled here by queueing them when their watcher gets executed. |
613 | \& - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
817 | \& \- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
614 | \& were used, return, otherwise continue with step *. |
818 | \& were used, or there are no active watchers, return, otherwise |
|
|
819 | \& continue with step *. |
615 | .Ve |
820 | .Ve |
616 | .Sp |
821 | .Sp |
617 | Example: queue some jobs and then loop until no events are outsanding |
822 | Example: Queue some jobs and then loop until no events are outstanding |
618 | anymore. |
823 | anymore. |
619 | .Sp |
824 | .Sp |
620 | .Vb 4 |
825 | .Vb 4 |
621 | \& ... queue jobs here, make sure they register event watchers as long |
826 | \& ... queue jobs here, make sure they register event watchers as long |
622 | \& ... as they still have work to do (even an idle watcher will do..) |
827 | \& ... as they still have work to do (even an idle watcher will do..) |
623 | \& ev_loop (my_loop, 0); |
828 | \& ev_loop (my_loop, 0); |
624 | \& ... jobs done. yeah! |
829 | \& ... jobs done or somebody called unloop. yeah! |
625 | .Ve |
830 | .Ve |
626 | .IP "ev_unloop (loop, how)" 4 |
831 | .IP "ev_unloop (loop, how)" 4 |
627 | .IX Item "ev_unloop (loop, how)" |
832 | .IX Item "ev_unloop (loop, how)" |
628 | Can be used to make a call to \f(CW\*(C`ev_loop\*(C'\fR return early (but only after it |
833 | Can be used to make a call to \f(CW\*(C`ev_loop\*(C'\fR return early (but only after it |
629 | has processed all outstanding events). The \f(CW\*(C`how\*(C'\fR argument must be either |
834 | has processed all outstanding events). The \f(CW\*(C`how\*(C'\fR argument must be either |
630 | \&\f(CW\*(C`EVUNLOOP_ONE\*(C'\fR, which will make the innermost \f(CW\*(C`ev_loop\*(C'\fR call return, or |
835 | \&\f(CW\*(C`EVUNLOOP_ONE\*(C'\fR, which will make the innermost \f(CW\*(C`ev_loop\*(C'\fR call return, or |
631 | \&\f(CW\*(C`EVUNLOOP_ALL\*(C'\fR, which will make all nested \f(CW\*(C`ev_loop\*(C'\fR calls return. |
836 | \&\f(CW\*(C`EVUNLOOP_ALL\*(C'\fR, which will make all nested \f(CW\*(C`ev_loop\*(C'\fR calls return. |
|
|
837 | .Sp |
|
|
838 | This \*(L"unloop state\*(R" will be cleared when entering \f(CW\*(C`ev_loop\*(C'\fR again. |
|
|
839 | .Sp |
|
|
840 | It is safe to call \f(CW\*(C`ev_unloop\*(C'\fR from otuside any \f(CW\*(C`ev_loop\*(C'\fR calls. |
632 | .IP "ev_ref (loop)" 4 |
841 | .IP "ev_ref (loop)" 4 |
633 | .IX Item "ev_ref (loop)" |
842 | .IX Item "ev_ref (loop)" |
634 | .PD 0 |
843 | .PD 0 |
635 | .IP "ev_unref (loop)" 4 |
844 | .IP "ev_unref (loop)" 4 |
636 | .IX Item "ev_unref (loop)" |
845 | .IX Item "ev_unref (loop)" |
637 | .PD |
846 | .PD |
638 | Ref/unref can be used to add or remove a reference count on the event |
847 | Ref/unref can be used to add or remove a reference count on the event |
639 | loop: Every watcher keeps one reference, and as long as the reference |
848 | loop: Every watcher keeps one reference, and as long as the reference |
640 | count is nonzero, \f(CW\*(C`ev_loop\*(C'\fR will not return on its own. If you have |
849 | count is nonzero, \f(CW\*(C`ev_loop\*(C'\fR will not return on its own. |
|
|
850 | .Sp |
641 | a watcher you never unregister that should not keep \f(CW\*(C`ev_loop\*(C'\fR from |
851 | If you have a watcher you never unregister that should not keep \f(CW\*(C`ev_loop\*(C'\fR |
642 | returning, \fIev_unref()\fR after starting, and \fIev_ref()\fR before stopping it. For |
852 | from returning, call \fIev_unref()\fR after starting, and \fIev_ref()\fR before |
|
|
853 | stopping it. |
|
|
854 | .Sp |
643 | example, libev itself uses this for its internal signal pipe: It is not |
855 | As an example, libev itself uses this for its internal signal pipe: It is |
644 | visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from exiting if |
856 | not visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from exiting |
645 | no event watchers registered by it are active. It is also an excellent |
857 | if no event watchers registered by it are active. It is also an excellent |
646 | way to do this for generic recurring timers or from within third-party |
858 | way to do this for generic recurring timers or from within third-party |
647 | libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR. |
859 | libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR |
|
|
860 | (but only if the watcher wasn't active before, or was active before, |
|
|
861 | respectively). |
648 | .Sp |
862 | .Sp |
649 | Example: create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR |
863 | Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR |
650 | running when nothing else is active. |
864 | running when nothing else is active. |
651 | .Sp |
865 | .Sp |
652 | .Vb 4 |
866 | .Vb 4 |
653 | \& struct dv_signal exitsig; |
867 | \& ev_signal exitsig; |
654 | \& ev_signal_init (&exitsig, sig_cb, SIGINT); |
868 | \& ev_signal_init (&exitsig, sig_cb, SIGINT); |
655 | \& ev_signal_start (myloop, &exitsig); |
869 | \& ev_signal_start (loop, &exitsig); |
656 | \& evf_unref (myloop); |
870 | \& evf_unref (loop); |
657 | .Ve |
871 | .Ve |
658 | .Sp |
872 | .Sp |
659 | Example: for some weird reason, unregister the above signal handler again. |
873 | Example: For some weird reason, unregister the above signal handler again. |
660 | .Sp |
874 | .Sp |
661 | .Vb 2 |
875 | .Vb 2 |
662 | \& ev_ref (myloop); |
876 | \& ev_ref (loop); |
663 | \& ev_signal_stop (myloop, &exitsig); |
877 | \& ev_signal_stop (loop, &exitsig); |
664 | .Ve |
878 | .Ve |
|
|
879 | .IP "ev_set_io_collect_interval (loop, ev_tstamp interval)" 4 |
|
|
880 | .IX Item "ev_set_io_collect_interval (loop, ev_tstamp interval)" |
|
|
881 | .PD 0 |
|
|
882 | .IP "ev_set_timeout_collect_interval (loop, ev_tstamp interval)" 4 |
|
|
883 | .IX Item "ev_set_timeout_collect_interval (loop, ev_tstamp interval)" |
|
|
884 | .PD |
|
|
885 | These advanced functions influence the time that libev will spend waiting |
|
|
886 | for events. Both time intervals are by default \f(CW0\fR, meaning that libev |
|
|
887 | will try to invoke timer/periodic callbacks and I/O callbacks with minimum |
|
|
888 | latency. |
|
|
889 | .Sp |
|
|
890 | Setting these to a higher value (the \f(CW\*(C`interval\*(C'\fR \fImust\fR be >= \f(CW0\fR) |
|
|
891 | allows libev to delay invocation of I/O and timer/periodic callbacks |
|
|
892 | to increase efficiency of loop iterations (or to increase power-saving |
|
|
893 | opportunities). |
|
|
894 | .Sp |
|
|
895 | The idea is that sometimes your program runs just fast enough to handle |
|
|
896 | one (or very few) event(s) per loop iteration. While this makes the |
|
|
897 | program responsive, it also wastes a lot of \s-1CPU\s0 time to poll for new |
|
|
898 | events, especially with backends like \f(CW\*(C`select ()\*(C'\fR which have a high |
|
|
899 | overhead for the actual polling but can deliver many events at once. |
|
|
900 | .Sp |
|
|
901 | By setting a higher \fIio collect interval\fR you allow libev to spend more |
|
|
902 | time collecting I/O events, so you can handle more events per iteration, |
|
|
903 | at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and |
|
|
904 | \&\f(CW\*(C`ev_timer\*(C'\fR) will be not affected. Setting this to a non-null value will |
|
|
905 | introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations. |
|
|
906 | .Sp |
|
|
907 | Likewise, by setting a higher \fItimeout collect interval\fR you allow libev |
|
|
908 | to spend more time collecting timeouts, at the expense of increased |
|
|
909 | latency/jitter/inexactness (the watcher callback will be called |
|
|
910 | later). \f(CW\*(C`ev_io\*(C'\fR watchers will not be affected. Setting this to a non-null |
|
|
911 | value will not introduce any overhead in libev. |
|
|
912 | .Sp |
|
|
913 | Many (busy) programs can usually benefit by setting the I/O collect |
|
|
914 | interval to a value near \f(CW0.1\fR or so, which is often enough for |
|
|
915 | interactive servers (of course not for games), likewise for timeouts. It |
|
|
916 | usually doesn't make much sense to set it to a lower value than \f(CW0.01\fR, |
|
|
917 | as this approaches the timing granularity of most systems. |
|
|
918 | .Sp |
|
|
919 | Setting the \fItimeout collect interval\fR can improve the opportunity for |
|
|
920 | saving power, as the program will \*(L"bundle\*(R" timer callback invocations that |
|
|
921 | are \*(L"near\*(R" in time together, by delaying some, thus reducing the number of |
|
|
922 | times the process sleeps and wakes up again. Another useful technique to |
|
|
923 | reduce iterations/wake\-ups is to use \f(CW\*(C`ev_periodic\*(C'\fR watchers and make sure |
|
|
924 | they fire on, say, one-second boundaries only. |
|
|
925 | .IP "ev_loop_verify (loop)" 4 |
|
|
926 | .IX Item "ev_loop_verify (loop)" |
|
|
927 | This function only does something when \f(CW\*(C`EV_VERIFY\*(C'\fR support has been |
|
|
928 | compiled in, which is the default for non-minimal builds. It tries to go |
|
|
929 | through all internal structures and checks them for validity. If anything |
|
|
930 | is found to be inconsistent, it will print an error message to standard |
|
|
931 | error and call \f(CW\*(C`abort ()\*(C'\fR. |
|
|
932 | .Sp |
|
|
933 | This can be used to catch bugs inside libev itself: under normal |
|
|
934 | circumstances, this function will never abort as of course libev keeps its |
|
|
935 | data structures consistent. |
665 | .SH "ANATOMY OF A WATCHER" |
936 | .SH "ANATOMY OF A WATCHER" |
666 | .IX Header "ANATOMY OF A WATCHER" |
937 | .IX Header "ANATOMY OF A WATCHER" |
|
|
938 | In the following description, uppercase \f(CW\*(C`TYPE\*(C'\fR in names stands for the |
|
|
939 | watcher type, e.g. \f(CW\*(C`ev_TYPE_start\*(C'\fR can mean \f(CW\*(C`ev_timer_start\*(C'\fR for timer |
|
|
940 | watchers and \f(CW\*(C`ev_io_start\*(C'\fR for I/O watchers. |
|
|
941 | .PP |
667 | A watcher is a structure that you create and register to record your |
942 | A watcher is a structure that you create and register to record your |
668 | interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to |
943 | interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to |
669 | become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher for that: |
944 | become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher for that: |
670 | .PP |
945 | .PP |
671 | .Vb 5 |
946 | .Vb 5 |
672 | \& static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
947 | \& static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
673 | \& { |
948 | \& { |
674 | \& ev_io_stop (w); |
949 | \& ev_io_stop (w); |
675 | \& ev_unloop (loop, EVUNLOOP_ALL); |
950 | \& ev_unloop (loop, EVUNLOOP_ALL); |
676 | \& } |
951 | \& } |
677 | .Ve |
952 | \& |
678 | .PP |
|
|
679 | .Vb 6 |
|
|
680 | \& struct ev_loop *loop = ev_default_loop (0); |
953 | \& struct ev_loop *loop = ev_default_loop (0); |
|
|
954 | \& |
681 | \& struct ev_io stdin_watcher; |
955 | \& ev_io stdin_watcher; |
|
|
956 | \& |
682 | \& ev_init (&stdin_watcher, my_cb); |
957 | \& ev_init (&stdin_watcher, my_cb); |
683 | \& ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
958 | \& ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
684 | \& ev_io_start (loop, &stdin_watcher); |
959 | \& ev_io_start (loop, &stdin_watcher); |
|
|
960 | \& |
685 | \& ev_loop (loop, 0); |
961 | \& ev_loop (loop, 0); |
686 | .Ve |
962 | .Ve |
687 | .PP |
963 | .PP |
688 | As you can see, you are responsible for allocating the memory for your |
964 | As you can see, you are responsible for allocating the memory for your |
689 | watcher structures (and it is usually a bad idea to do this on the stack, |
965 | watcher structures (and it is \fIusually\fR a bad idea to do this on the |
690 | although this can sometimes be quite valid). |
966 | stack). |
|
|
967 | .PP |
|
|
968 | Each watcher has an associated watcher structure (called \f(CW\*(C`struct ev_TYPE\*(C'\fR |
|
|
969 | or simply \f(CW\*(C`ev_TYPE\*(C'\fR, as typedefs are provided for all watcher structs). |
691 | .PP |
970 | .PP |
692 | Each watcher structure must be initialised by a call to \f(CW\*(C`ev_init |
971 | Each watcher structure must be initialised by a call to \f(CW\*(C`ev_init |
693 | (watcher *, callback)\*(C'\fR, which expects a callback to be provided. This |
972 | (watcher *, callback)\*(C'\fR, which expects a callback to be provided. This |
694 | callback gets invoked each time the event occurs (or, in the case of io |
973 | callback gets invoked each time the event occurs (or, in the case of I/O |
695 | watchers, each time the event loop detects that the file descriptor given |
974 | watchers, each time the event loop detects that the file descriptor given |
696 | is readable and/or writable). |
975 | is readable and/or writable). |
697 | .PP |
976 | .PP |
698 | Each watcher type has its own \f(CW\*(C`ev_<type>_set (watcher *, ...)\*(C'\fR macro |
977 | Each watcher type further has its own \f(CW\*(C`ev_TYPE_set (watcher *, ...)\*(C'\fR |
699 | with arguments specific to this watcher type. There is also a macro |
978 | macro to configure it, with arguments specific to the watcher type. There |
700 | to combine initialisation and setting in one call: \f(CW\*(C`ev_<type>_init |
979 | is also a macro to combine initialisation and setting in one call: \f(CW\*(C`ev_TYPE_init (watcher *, callback, ...)\*(C'\fR. |
701 | (watcher *, callback, ...)\*(C'\fR. |
|
|
702 | .PP |
980 | .PP |
703 | To make the watcher actually watch out for events, you have to start it |
981 | To make the watcher actually watch out for events, you have to start it |
704 | with a watcher-specific start function (\f(CW\*(C`ev_<type>_start (loop, watcher |
982 | with a watcher-specific start function (\f(CW\*(C`ev_TYPE_start (loop, watcher |
705 | *)\*(C'\fR), and you can stop watching for events at any time by calling the |
983 | *)\*(C'\fR), and you can stop watching for events at any time by calling the |
706 | corresponding stop function (\f(CW\*(C`ev_<type>_stop (loop, watcher *)\*(C'\fR. |
984 | corresponding stop function (\f(CW\*(C`ev_TYPE_stop (loop, watcher *)\*(C'\fR. |
707 | .PP |
985 | .PP |
708 | As long as your watcher is active (has been started but not stopped) you |
986 | As long as your watcher is active (has been started but not stopped) you |
709 | must not touch the values stored in it. Most specifically you must never |
987 | must not touch the values stored in it. Most specifically you must never |
710 | reinitialise it or call its \f(CW\*(C`set\*(C'\fR macro. |
988 | reinitialise it or call its \f(CW\*(C`ev_TYPE_set\*(C'\fR macro. |
711 | .PP |
989 | .PP |
712 | Each and every callback receives the event loop pointer as first, the |
990 | Each and every callback receives the event loop pointer as first, the |
713 | registered watcher structure as second, and a bitset of received events as |
991 | registered watcher structure as second, and a bitset of received events as |
714 | third argument. |
992 | third argument. |
715 | .PP |
993 | .PP |
… | |
… | |
772 | .ie n .IP """EV_FORK""" 4 |
1050 | .ie n .IP """EV_FORK""" 4 |
773 | .el .IP "\f(CWEV_FORK\fR" 4 |
1051 | .el .IP "\f(CWEV_FORK\fR" 4 |
774 | .IX Item "EV_FORK" |
1052 | .IX Item "EV_FORK" |
775 | The event loop has been resumed in the child process after fork (see |
1053 | The event loop has been resumed in the child process after fork (see |
776 | \&\f(CW\*(C`ev_fork\*(C'\fR). |
1054 | \&\f(CW\*(C`ev_fork\*(C'\fR). |
|
|
1055 | .ie n .IP """EV_ASYNC""" 4 |
|
|
1056 | .el .IP "\f(CWEV_ASYNC\fR" 4 |
|
|
1057 | .IX Item "EV_ASYNC" |
|
|
1058 | The given async watcher has been asynchronously notified (see \f(CW\*(C`ev_async\*(C'\fR). |
777 | .ie n .IP """EV_ERROR""" 4 |
1059 | .ie n .IP """EV_ERROR""" 4 |
778 | .el .IP "\f(CWEV_ERROR\fR" 4 |
1060 | .el .IP "\f(CWEV_ERROR\fR" 4 |
779 | .IX Item "EV_ERROR" |
1061 | .IX Item "EV_ERROR" |
780 | An unspecified error has occured, the watcher has been stopped. This might |
1062 | An unspecified error has occurred, the watcher has been stopped. This might |
781 | happen because the watcher could not be properly started because libev |
1063 | happen because the watcher could not be properly started because libev |
782 | ran out of memory, a file descriptor was found to be closed or any other |
1064 | ran out of memory, a file descriptor was found to be closed or any other |
|
|
1065 | problem. Libev considers these application bugs. |
|
|
1066 | .Sp |
783 | problem. You best act on it by reporting the problem and somehow coping |
1067 | You best act on it by reporting the problem and somehow coping with the |
784 | with the watcher being stopped. |
1068 | watcher being stopped. Note that well-written programs should not receive |
|
|
1069 | an error ever, so when your watcher receives it, this usually indicates a |
|
|
1070 | bug in your program. |
785 | .Sp |
1071 | .Sp |
786 | Libev will usually signal a few \*(L"dummy\*(R" events together with an error, |
1072 | Libev will usually signal a few \*(L"dummy\*(R" events together with an error, for |
787 | for example it might indicate that a fd is readable or writable, and if |
1073 | example it might indicate that a fd is readable or writable, and if your |
788 | your callbacks is well-written it can just attempt the operation and cope |
1074 | callbacks is well-written it can just attempt the operation and cope with |
789 | with the error from \fIread()\fR or \fIwrite()\fR. This will not work in multithreaded |
1075 | the error from \fIread()\fR or \fIwrite()\fR. This will not work in multi-threaded |
790 | programs, though, so beware. |
1076 | programs, though, as the fd could already be closed and reused for another |
|
|
1077 | thing, so beware. |
791 | .Sh "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0" |
1078 | .Sh "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0" |
792 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
1079 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
793 | In the following description, \f(CW\*(C`TYPE\*(C'\fR stands for the watcher type, |
|
|
794 | e.g. \f(CW\*(C`timer\*(C'\fR for \f(CW\*(C`ev_timer\*(C'\fR watchers and \f(CW\*(C`io\*(C'\fR for \f(CW\*(C`ev_io\*(C'\fR watchers. |
|
|
795 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
1080 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
796 | .el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 |
1081 | .el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 |
797 | .IX Item "ev_init (ev_TYPE *watcher, callback)" |
1082 | .IX Item "ev_init (ev_TYPE *watcher, callback)" |
798 | This macro initialises the generic portion of a watcher. The contents |
1083 | This macro initialises the generic portion of a watcher. The contents |
799 | of the watcher object can be arbitrary (so \f(CW\*(C`malloc\*(C'\fR will do). Only |
1084 | of the watcher object can be arbitrary (so \f(CW\*(C`malloc\*(C'\fR will do). Only |
… | |
… | |
803 | which rolls both calls into one. |
1088 | which rolls both calls into one. |
804 | .Sp |
1089 | .Sp |
805 | You can reinitialise a watcher at any time as long as it has been stopped |
1090 | You can reinitialise a watcher at any time as long as it has been stopped |
806 | (or never started) and there are no pending events outstanding. |
1091 | (or never started) and there are no pending events outstanding. |
807 | .Sp |
1092 | .Sp |
808 | The callback is always of type \f(CW\*(C`void (*)(ev_loop *loop, ev_TYPE *watcher, |
1093 | The callback is always of type \f(CW\*(C`void (*)(struct ev_loop *loop, ev_TYPE *watcher, |
809 | int revents)\*(C'\fR. |
1094 | int revents)\*(C'\fR. |
|
|
1095 | .Sp |
|
|
1096 | Example: Initialise an \f(CW\*(C`ev_io\*(C'\fR watcher in two steps. |
|
|
1097 | .Sp |
|
|
1098 | .Vb 3 |
|
|
1099 | \& ev_io w; |
|
|
1100 | \& ev_init (&w, my_cb); |
|
|
1101 | \& ev_io_set (&w, STDIN_FILENO, EV_READ); |
|
|
1102 | .Ve |
810 | .ie n .IP """ev_TYPE_set"" (ev_TYPE *, [args])" 4 |
1103 | .ie n .IP """ev_TYPE_set"" (ev_TYPE *, [args])" 4 |
811 | .el .IP "\f(CWev_TYPE_set\fR (ev_TYPE *, [args])" 4 |
1104 | .el .IP "\f(CWev_TYPE_set\fR (ev_TYPE *, [args])" 4 |
812 | .IX Item "ev_TYPE_set (ev_TYPE *, [args])" |
1105 | .IX Item "ev_TYPE_set (ev_TYPE *, [args])" |
813 | This macro initialises the type-specific parts of a watcher. You need to |
1106 | This macro initialises the type-specific parts of a watcher. You need to |
814 | call \f(CW\*(C`ev_init\*(C'\fR at least once before you call this macro, but you can |
1107 | call \f(CW\*(C`ev_init\*(C'\fR at least once before you call this macro, but you can |
… | |
… | |
816 | macro on a watcher that is active (it can be pending, however, which is a |
1109 | macro on a watcher that is active (it can be pending, however, which is a |
817 | difference to the \f(CW\*(C`ev_init\*(C'\fR macro). |
1110 | difference to the \f(CW\*(C`ev_init\*(C'\fR macro). |
818 | .Sp |
1111 | .Sp |
819 | Although some watcher types do not have type-specific arguments |
1112 | Although some watcher types do not have type-specific arguments |
820 | (e.g. \f(CW\*(C`ev_prepare\*(C'\fR) you still need to call its \f(CW\*(C`set\*(C'\fR macro. |
1113 | (e.g. \f(CW\*(C`ev_prepare\*(C'\fR) you still need to call its \f(CW\*(C`set\*(C'\fR macro. |
|
|
1114 | .Sp |
|
|
1115 | See \f(CW\*(C`ev_init\*(C'\fR, above, for an example. |
821 | .ie n .IP """ev_TYPE_init"" (ev_TYPE *watcher, callback, [args])" 4 |
1116 | .ie n .IP """ev_TYPE_init"" (ev_TYPE *watcher, callback, [args])" 4 |
822 | .el .IP "\f(CWev_TYPE_init\fR (ev_TYPE *watcher, callback, [args])" 4 |
1117 | .el .IP "\f(CWev_TYPE_init\fR (ev_TYPE *watcher, callback, [args])" 4 |
823 | .IX Item "ev_TYPE_init (ev_TYPE *watcher, callback, [args])" |
1118 | .IX Item "ev_TYPE_init (ev_TYPE *watcher, callback, [args])" |
824 | This convinience macro rolls both \f(CW\*(C`ev_init\*(C'\fR and \f(CW\*(C`ev_TYPE_set\*(C'\fR macro |
1119 | This convenience macro rolls both \f(CW\*(C`ev_init\*(C'\fR and \f(CW\*(C`ev_TYPE_set\*(C'\fR macro |
825 | calls into a single call. This is the most convinient method to initialise |
1120 | calls into a single call. This is the most convenient method to initialise |
826 | a watcher. The same limitations apply, of course. |
1121 | a watcher. The same limitations apply, of course. |
|
|
1122 | .Sp |
|
|
1123 | Example: Initialise and set an \f(CW\*(C`ev_io\*(C'\fR watcher in one step. |
|
|
1124 | .Sp |
|
|
1125 | .Vb 1 |
|
|
1126 | \& ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
|
|
1127 | .Ve |
827 | .ie n .IP """ev_TYPE_start"" (loop *, ev_TYPE *watcher)" 4 |
1128 | .ie n .IP """ev_TYPE_start"" (loop *, ev_TYPE *watcher)" 4 |
828 | .el .IP "\f(CWev_TYPE_start\fR (loop *, ev_TYPE *watcher)" 4 |
1129 | .el .IP "\f(CWev_TYPE_start\fR (loop *, ev_TYPE *watcher)" 4 |
829 | .IX Item "ev_TYPE_start (loop *, ev_TYPE *watcher)" |
1130 | .IX Item "ev_TYPE_start (loop *, ev_TYPE *watcher)" |
830 | Starts (activates) the given watcher. Only active watchers will receive |
1131 | Starts (activates) the given watcher. Only active watchers will receive |
831 | events. If the watcher is already active nothing will happen. |
1132 | events. If the watcher is already active nothing will happen. |
|
|
1133 | .Sp |
|
|
1134 | Example: Start the \f(CW\*(C`ev_io\*(C'\fR watcher that is being abused as example in this |
|
|
1135 | whole section. |
|
|
1136 | .Sp |
|
|
1137 | .Vb 1 |
|
|
1138 | \& ev_io_start (EV_DEFAULT_UC, &w); |
|
|
1139 | .Ve |
832 | .ie n .IP """ev_TYPE_stop"" (loop *, ev_TYPE *watcher)" 4 |
1140 | .ie n .IP """ev_TYPE_stop"" (loop *, ev_TYPE *watcher)" 4 |
833 | .el .IP "\f(CWev_TYPE_stop\fR (loop *, ev_TYPE *watcher)" 4 |
1141 | .el .IP "\f(CWev_TYPE_stop\fR (loop *, ev_TYPE *watcher)" 4 |
834 | .IX Item "ev_TYPE_stop (loop *, ev_TYPE *watcher)" |
1142 | .IX Item "ev_TYPE_stop (loop *, ev_TYPE *watcher)" |
835 | Stops the given watcher again (if active) and clears the pending |
1143 | Stops the given watcher if active, and clears the pending status (whether |
|
|
1144 | the watcher was active or not). |
|
|
1145 | .Sp |
836 | status. It is possible that stopped watchers are pending (for example, |
1146 | It is possible that stopped watchers are pending \- for example, |
837 | non-repeating timers are being stopped when they become pending), but |
1147 | non-repeating timers are being stopped when they become pending \- but |
838 | \&\f(CW\*(C`ev_TYPE_stop\*(C'\fR ensures that the watcher is neither active nor pending. If |
1148 | calling \f(CW\*(C`ev_TYPE_stop\*(C'\fR ensures that the watcher is neither active nor |
839 | you want to free or reuse the memory used by the watcher it is therefore a |
1149 | pending. If you want to free or reuse the memory used by the watcher it is |
840 | good idea to always call its \f(CW\*(C`ev_TYPE_stop\*(C'\fR function. |
1150 | therefore a good idea to always call its \f(CW\*(C`ev_TYPE_stop\*(C'\fR function. |
841 | .IP "bool ev_is_active (ev_TYPE *watcher)" 4 |
1151 | .IP "bool ev_is_active (ev_TYPE *watcher)" 4 |
842 | .IX Item "bool ev_is_active (ev_TYPE *watcher)" |
1152 | .IX Item "bool ev_is_active (ev_TYPE *watcher)" |
843 | Returns a true value iff the watcher is active (i.e. it has been started |
1153 | Returns a true value iff the watcher is active (i.e. it has been started |
844 | and not yet been stopped). As long as a watcher is active you must not modify |
1154 | and not yet been stopped). As long as a watcher is active you must not modify |
845 | it. |
1155 | it. |
846 | .IP "bool ev_is_pending (ev_TYPE *watcher)" 4 |
1156 | .IP "bool ev_is_pending (ev_TYPE *watcher)" 4 |
847 | .IX Item "bool ev_is_pending (ev_TYPE *watcher)" |
1157 | .IX Item "bool ev_is_pending (ev_TYPE *watcher)" |
848 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
1158 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
849 | events but its callback has not yet been invoked). As long as a watcher |
1159 | events but its callback has not yet been invoked). As long as a watcher |
850 | is pending (but not active) you must not call an init function on it (but |
1160 | is pending (but not active) you must not call an init function on it (but |
851 | \&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe) and you must make sure the watcher is available to |
1161 | \&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe), you must not change its priority, and you must |
852 | libev (e.g. you cnanot \f(CW\*(C`free ()\*(C'\fR it). |
1162 | make sure the watcher is available to libev (e.g. you cannot \f(CW\*(C`free ()\*(C'\fR |
|
|
1163 | it). |
853 | .IP "callback = ev_cb (ev_TYPE *watcher)" 4 |
1164 | .IP "callback ev_cb (ev_TYPE *watcher)" 4 |
854 | .IX Item "callback = ev_cb (ev_TYPE *watcher)" |
1165 | .IX Item "callback ev_cb (ev_TYPE *watcher)" |
855 | Returns the callback currently set on the watcher. |
1166 | Returns the callback currently set on the watcher. |
856 | .IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 |
1167 | .IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 |
857 | .IX Item "ev_cb_set (ev_TYPE *watcher, callback)" |
1168 | .IX Item "ev_cb_set (ev_TYPE *watcher, callback)" |
858 | Change the callback. You can change the callback at virtually any time |
1169 | Change the callback. You can change the callback at virtually any time |
859 | (modulo threads). |
1170 | (modulo threads). |
|
|
1171 | .IP "ev_set_priority (ev_TYPE *watcher, priority)" 4 |
|
|
1172 | .IX Item "ev_set_priority (ev_TYPE *watcher, priority)" |
|
|
1173 | .PD 0 |
|
|
1174 | .IP "int ev_priority (ev_TYPE *watcher)" 4 |
|
|
1175 | .IX Item "int ev_priority (ev_TYPE *watcher)" |
|
|
1176 | .PD |
|
|
1177 | Set and query the priority of the watcher. The priority is a small |
|
|
1178 | integer between \f(CW\*(C`EV_MAXPRI\*(C'\fR (default: \f(CW2\fR) and \f(CW\*(C`EV_MINPRI\*(C'\fR |
|
|
1179 | (default: \f(CW\*(C`\-2\*(C'\fR). Pending watchers with higher priority will be invoked |
|
|
1180 | before watchers with lower priority, but priority will not keep watchers |
|
|
1181 | from being executed (except for \f(CW\*(C`ev_idle\*(C'\fR watchers). |
|
|
1182 | .Sp |
|
|
1183 | This means that priorities are \fIonly\fR used for ordering callback |
|
|
1184 | invocation after new events have been received. This is useful, for |
|
|
1185 | example, to reduce latency after idling, or more often, to bind two |
|
|
1186 | watchers on the same event and make sure one is called first. |
|
|
1187 | .Sp |
|
|
1188 | If you need to suppress invocation when higher priority events are pending |
|
|
1189 | you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality. |
|
|
1190 | .Sp |
|
|
1191 | You \fImust not\fR change the priority of a watcher as long as it is active or |
|
|
1192 | pending. |
|
|
1193 | .Sp |
|
|
1194 | The default priority used by watchers when no priority has been set is |
|
|
1195 | always \f(CW0\fR, which is supposed to not be too high and not be too low :). |
|
|
1196 | .Sp |
|
|
1197 | Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is |
|
|
1198 | fine, as long as you do not mind that the priority value you query might |
|
|
1199 | or might not have been clamped to the valid range. |
|
|
1200 | .IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4 |
|
|
1201 | .IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)" |
|
|
1202 | 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 |
|
|
1203 | \&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback |
|
|
1204 | can deal with that fact, as both are simply passed through to the |
|
|
1205 | callback. |
|
|
1206 | .IP "int ev_clear_pending (loop, ev_TYPE *watcher)" 4 |
|
|
1207 | .IX Item "int ev_clear_pending (loop, ev_TYPE *watcher)" |
|
|
1208 | If the watcher is pending, this function clears its pending status and |
|
|
1209 | returns its \f(CW\*(C`revents\*(C'\fR bitset (as if its callback was invoked). If the |
|
|
1210 | watcher isn't pending it does nothing and returns \f(CW0\fR. |
|
|
1211 | .Sp |
|
|
1212 | Sometimes it can be useful to \*(L"poll\*(R" a watcher instead of waiting for its |
|
|
1213 | callback to be invoked, which can be accomplished with this function. |
860 | .Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" |
1214 | .Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" |
861 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
1215 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
862 | Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change |
1216 | Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change |
863 | and read at any time, libev will completely ignore it. This can be used |
1217 | and read at any time: libev will completely ignore it. This can be used |
864 | to associate arbitrary data with your watcher. If you need more data and |
1218 | to associate arbitrary data with your watcher. If you need more data and |
865 | don't want to allocate memory and store a pointer to it in that data |
1219 | don't want to allocate memory and store a pointer to it in that data |
866 | member, you can also \*(L"subclass\*(R" the watcher type and provide your own |
1220 | member, you can also \*(L"subclass\*(R" the watcher type and provide your own |
867 | data: |
1221 | data: |
868 | .PP |
1222 | .PP |
869 | .Vb 7 |
1223 | .Vb 7 |
870 | \& struct my_io |
1224 | \& struct my_io |
871 | \& { |
1225 | \& { |
872 | \& struct ev_io io; |
1226 | \& ev_io io; |
873 | \& int otherfd; |
1227 | \& int otherfd; |
874 | \& void *somedata; |
1228 | \& void *somedata; |
875 | \& struct whatever *mostinteresting; |
1229 | \& struct whatever *mostinteresting; |
876 | \& } |
1230 | \& }; |
|
|
1231 | \& |
|
|
1232 | \& ... |
|
|
1233 | \& struct my_io w; |
|
|
1234 | \& ev_io_init (&w.io, my_cb, fd, EV_READ); |
877 | .Ve |
1235 | .Ve |
878 | .PP |
1236 | .PP |
879 | And since your callback will be called with a pointer to the watcher, you |
1237 | And since your callback will be called with a pointer to the watcher, you |
880 | can cast it back to your own type: |
1238 | can cast it back to your own type: |
881 | .PP |
1239 | .PP |
882 | .Vb 5 |
1240 | .Vb 5 |
883 | \& static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents) |
1241 | \& static void my_cb (struct ev_loop *loop, ev_io *w_, int revents) |
884 | \& { |
1242 | \& { |
885 | \& struct my_io *w = (struct my_io *)w_; |
1243 | \& struct my_io *w = (struct my_io *)w_; |
886 | \& ... |
1244 | \& ... |
887 | \& } |
1245 | \& } |
888 | .Ve |
1246 | .Ve |
889 | .PP |
1247 | .PP |
890 | More interesting and less C\-conformant ways of catsing your callback type |
1248 | More interesting and less C\-conformant ways of casting your callback type |
891 | have been omitted.... |
1249 | instead have been omitted. |
|
|
1250 | .PP |
|
|
1251 | Another common scenario is to use some data structure with multiple |
|
|
1252 | embedded watchers: |
|
|
1253 | .PP |
|
|
1254 | .Vb 6 |
|
|
1255 | \& struct my_biggy |
|
|
1256 | \& { |
|
|
1257 | \& int some_data; |
|
|
1258 | \& ev_timer t1; |
|
|
1259 | \& ev_timer t2; |
|
|
1260 | \& } |
|
|
1261 | .Ve |
|
|
1262 | .PP |
|
|
1263 | In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more |
|
|
1264 | complicated: Either you store the address of your \f(CW\*(C`my_biggy\*(C'\fR struct |
|
|
1265 | in the \f(CW\*(C`data\*(C'\fR member of the watcher (for woozies), or you need to use |
|
|
1266 | some pointer arithmetic using \f(CW\*(C`offsetof\*(C'\fR inside your watchers (for real |
|
|
1267 | programmers): |
|
|
1268 | .PP |
|
|
1269 | .Vb 1 |
|
|
1270 | \& #include <stddef.h> |
|
|
1271 | \& |
|
|
1272 | \& static void |
|
|
1273 | \& t1_cb (EV_P_ ev_timer *w, int revents) |
|
|
1274 | \& { |
|
|
1275 | \& struct my_biggy big = (struct my_biggy * |
|
|
1276 | \& (((char *)w) \- offsetof (struct my_biggy, t1)); |
|
|
1277 | \& } |
|
|
1278 | \& |
|
|
1279 | \& static void |
|
|
1280 | \& t2_cb (EV_P_ ev_timer *w, int revents) |
|
|
1281 | \& { |
|
|
1282 | \& struct my_biggy big = (struct my_biggy * |
|
|
1283 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
|
|
1284 | \& } |
|
|
1285 | .Ve |
892 | .SH "WATCHER TYPES" |
1286 | .SH "WATCHER TYPES" |
893 | .IX Header "WATCHER TYPES" |
1287 | .IX Header "WATCHER TYPES" |
894 | This section describes each watcher in detail, but will not repeat |
1288 | This section describes each watcher in detail, but will not repeat |
895 | information given in the last section. Any initialisation/set macros, |
1289 | information given in the last section. Any initialisation/set macros, |
896 | functions and members specific to the watcher type are explained. |
1290 | functions and members specific to the watcher type are explained. |
… | |
… | |
917 | In general you can register as many read and/or write event watchers per |
1311 | In general you can register as many read and/or write event watchers per |
918 | fd as you want (as long as you don't confuse yourself). Setting all file |
1312 | fd as you want (as long as you don't confuse yourself). Setting all file |
919 | descriptors to non-blocking mode is also usually a good idea (but not |
1313 | descriptors to non-blocking mode is also usually a good idea (but not |
920 | required if you know what you are doing). |
1314 | required if you know what you are doing). |
921 | .PP |
1315 | .PP |
922 | You have to be careful with dup'ed file descriptors, though. Some backends |
1316 | If you cannot use non-blocking mode, then force the use of a |
923 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
1317 | known-to-be-good backend (at the time of this writing, this includes only |
924 | descriptors correctly if you register interest in two or more fds pointing |
1318 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and \f(CW\*(C`EVBACKEND_POLL\*(C'\fR). |
925 | to the same underlying file/socket/etc. description (that is, they share |
|
|
926 | the same underlying \*(L"file open\*(R"). |
|
|
927 | .PP |
|
|
928 | If you must do this, then force the use of a known-to-be-good backend |
|
|
929 | (at the time of this writing, this includes only \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and |
|
|
930 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR). |
|
|
931 | .PP |
1319 | .PP |
932 | Another thing you have to watch out for is that it is quite easy to |
1320 | Another thing you have to watch out for is that it is quite easy to |
933 | receive \*(L"spurious\*(R" readyness notifications, that is your callback might |
1321 | receive \*(L"spurious\*(R" readiness notifications, that is your callback might |
934 | be called with \f(CW\*(C`EV_READ\*(C'\fR but a subsequent \f(CW\*(C`read\*(C'\fR(2) will actually block |
1322 | be called with \f(CW\*(C`EV_READ\*(C'\fR but a subsequent \f(CW\*(C`read\*(C'\fR(2) will actually block |
935 | because there is no data. Not only are some backends known to create a |
1323 | because there is no data. Not only are some backends known to create a |
936 | lot of those (for example solaris ports), it is very easy to get into |
1324 | lot of those (for example Solaris ports), it is very easy to get into |
937 | this situation even with a relatively standard program structure. Thus |
1325 | this situation even with a relatively standard program structure. Thus |
938 | it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning |
1326 | it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning |
939 | \&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives. |
1327 | \&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives. |
940 | .PP |
1328 | .PP |
941 | If you cannot run the fd in non-blocking mode (for example you should not |
1329 | If you cannot run the fd in non-blocking mode (for example you should |
942 | play around with an Xlib connection), then you have to seperately re-test |
1330 | not play around with an Xlib connection), then you have to separately |
943 | wether a file descriptor is really ready with a known-to-be good interface |
1331 | re-test whether a file descriptor is really ready with a known-to-be good |
944 | such as poll (fortunately in our Xlib example, Xlib already does this on |
1332 | interface such as poll (fortunately in our Xlib example, Xlib already |
945 | its own, so its quite safe to use). |
1333 | does this on its own, so its quite safe to use). Some people additionally |
|
|
1334 | use \f(CW\*(C`SIGALRM\*(C'\fR and an interval timer, just to be sure you won't block |
|
|
1335 | indefinitely. |
|
|
1336 | .PP |
|
|
1337 | But really, best use non-blocking mode. |
|
|
1338 | .PP |
|
|
1339 | \fIThe special problem of disappearing file descriptors\fR |
|
|
1340 | .IX Subsection "The special problem of disappearing file descriptors" |
|
|
1341 | .PP |
|
|
1342 | Some backends (e.g. kqueue, epoll) need to be told about closing a file |
|
|
1343 | descriptor (either due to calling \f(CW\*(C`close\*(C'\fR explicitly or any other means, |
|
|
1344 | such as \f(CW\*(C`dup2\*(C'\fR). The reason is that you register interest in some file |
|
|
1345 | descriptor, but when it goes away, the operating system will silently drop |
|
|
1346 | this interest. If another file descriptor with the same number then is |
|
|
1347 | registered with libev, there is no efficient way to see that this is, in |
|
|
1348 | fact, a different file descriptor. |
|
|
1349 | .PP |
|
|
1350 | To avoid having to explicitly tell libev about such cases, libev follows |
|
|
1351 | the following policy: Each time \f(CW\*(C`ev_io_set\*(C'\fR is being called, libev |
|
|
1352 | will assume that this is potentially a new file descriptor, otherwise |
|
|
1353 | it is assumed that the file descriptor stays the same. That means that |
|
|
1354 | 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 |
|
|
1355 | descriptor even if the file descriptor number itself did not change. |
|
|
1356 | .PP |
|
|
1357 | This is how one would do it normally anyway, the important point is that |
|
|
1358 | the libev application should not optimise around libev but should leave |
|
|
1359 | optimisations to libev. |
|
|
1360 | .PP |
|
|
1361 | \fIThe special problem of dup'ed file descriptors\fR |
|
|
1362 | .IX Subsection "The special problem of dup'ed file descriptors" |
|
|
1363 | .PP |
|
|
1364 | Some backends (e.g. epoll), cannot register events for file descriptors, |
|
|
1365 | but only events for the underlying file descriptions. That means when you |
|
|
1366 | have \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors or weirder constellations, and register |
|
|
1367 | events for them, only one file descriptor might actually receive events. |
|
|
1368 | .PP |
|
|
1369 | There is no workaround possible except not registering events |
|
|
1370 | for potentially \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors, or to resort to |
|
|
1371 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
|
|
1372 | .PP |
|
|
1373 | \fIThe special problem of fork\fR |
|
|
1374 | .IX Subsection "The special problem of fork" |
|
|
1375 | .PP |
|
|
1376 | Some backends (epoll, kqueue) do not support \f(CW\*(C`fork ()\*(C'\fR at all or exhibit |
|
|
1377 | useless behaviour. Libev fully supports fork, but needs to be told about |
|
|
1378 | it in the child. |
|
|
1379 | .PP |
|
|
1380 | To support fork in your programs, you either have to call |
|
|
1381 | \&\f(CW\*(C`ev_default_fork ()\*(C'\fR or \f(CW\*(C`ev_loop_fork ()\*(C'\fR after a fork in the child, |
|
|
1382 | enable \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR, or resort to \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or |
|
|
1383 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
|
|
1384 | .PP |
|
|
1385 | \fIThe special problem of \s-1SIGPIPE\s0\fR |
|
|
1386 | .IX Subsection "The special problem of SIGPIPE" |
|
|
1387 | .PP |
|
|
1388 | While not really specific to libev, it is easy to forget about \f(CW\*(C`SIGPIPE\*(C'\fR: |
|
|
1389 | when writing to a pipe whose other end has been closed, your program gets |
|
|
1390 | sent a \s-1SIGPIPE\s0, which, by default, aborts your program. For most programs |
|
|
1391 | this is sensible behaviour, for daemons, this is usually undesirable. |
|
|
1392 | .PP |
|
|
1393 | So when you encounter spurious, unexplained daemon exits, make sure you |
|
|
1394 | ignore \s-1SIGPIPE\s0 (and maybe make sure you log the exit status of your daemon |
|
|
1395 | somewhere, as that would have given you a big clue). |
|
|
1396 | .PP |
|
|
1397 | \fIWatcher-Specific Functions\fR |
|
|
1398 | .IX Subsection "Watcher-Specific Functions" |
946 | .IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 |
1399 | .IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 |
947 | .IX Item "ev_io_init (ev_io *, callback, int fd, int events)" |
1400 | .IX Item "ev_io_init (ev_io *, callback, int fd, int events)" |
948 | .PD 0 |
1401 | .PD 0 |
949 | .IP "ev_io_set (ev_io *, int fd, int events)" 4 |
1402 | .IP "ev_io_set (ev_io *, int fd, int events)" 4 |
950 | .IX Item "ev_io_set (ev_io *, int fd, int events)" |
1403 | .IX Item "ev_io_set (ev_io *, int fd, int events)" |
951 | .PD |
1404 | .PD |
952 | Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The \f(CW\*(C`fd\*(C'\fR is the file descriptor to |
1405 | Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The \f(CW\*(C`fd\*(C'\fR is the file descriptor to |
953 | rceeive events for and events is either \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or |
1406 | receive events for and \f(CW\*(C`events\*(C'\fR is either \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or |
954 | \&\f(CW\*(C`EV_READ | EV_WRITE\*(C'\fR to receive the given events. |
1407 | \&\f(CW\*(C`EV_READ | EV_WRITE\*(C'\fR, to express the desire to receive the given events. |
955 | .IP "int fd [read\-only]" 4 |
1408 | .IP "int fd [read\-only]" 4 |
956 | .IX Item "int fd [read-only]" |
1409 | .IX Item "int fd [read-only]" |
957 | The file descriptor being watched. |
1410 | The file descriptor being watched. |
958 | .IP "int events [read\-only]" 4 |
1411 | .IP "int events [read\-only]" 4 |
959 | .IX Item "int events [read-only]" |
1412 | .IX Item "int events [read-only]" |
960 | The events being watched. |
1413 | The events being watched. |
961 | .PP |
1414 | .PP |
|
|
1415 | \fIExamples\fR |
|
|
1416 | .IX Subsection "Examples" |
|
|
1417 | .PP |
962 | Example: call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well |
1418 | Example: Call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well |
963 | readable, but only once. Since it is likely line\-buffered, you could |
1419 | readable, but only once. Since it is likely line-buffered, you could |
964 | attempt to read a whole line in the callback: |
1420 | attempt to read a whole line in the callback. |
965 | .PP |
1421 | .PP |
966 | .Vb 6 |
1422 | .Vb 6 |
967 | \& static void |
1423 | \& static void |
968 | \& stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1424 | \& stdin_readable_cb (struct ev_loop *loop, ev_io *w, int revents) |
969 | \& { |
1425 | \& { |
970 | \& ev_io_stop (loop, w); |
1426 | \& ev_io_stop (loop, w); |
971 | \& .. read from stdin here (or from w->fd) and haqndle any I/O errors |
1427 | \& .. read from stdin here (or from w\->fd) and handle any I/O errors |
972 | \& } |
1428 | \& } |
973 | .Ve |
1429 | \& |
974 | .PP |
|
|
975 | .Vb 6 |
|
|
976 | \& ... |
1430 | \& ... |
977 | \& struct ev_loop *loop = ev_default_init (0); |
1431 | \& struct ev_loop *loop = ev_default_init (0); |
978 | \& struct ev_io stdin_readable; |
1432 | \& ev_io stdin_readable; |
979 | \& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1433 | \& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
980 | \& ev_io_start (loop, &stdin_readable); |
1434 | \& ev_io_start (loop, &stdin_readable); |
981 | \& ev_loop (loop, 0); |
1435 | \& ev_loop (loop, 0); |
982 | .Ve |
1436 | .Ve |
983 | .ie n .Sh """ev_timer"" \- relative and optionally repeating timeouts" |
1437 | .ie n .Sh """ev_timer"" \- relative and optionally repeating timeouts" |
984 | .el .Sh "\f(CWev_timer\fP \- relative and optionally repeating timeouts" |
1438 | .el .Sh "\f(CWev_timer\fP \- relative and optionally repeating timeouts" |
985 | .IX Subsection "ev_timer - relative and optionally repeating timeouts" |
1439 | .IX Subsection "ev_timer - relative and optionally repeating timeouts" |
986 | Timer watchers are simple relative timers that generate an event after a |
1440 | Timer watchers are simple relative timers that generate an event after a |
987 | given time, and optionally repeating in regular intervals after that. |
1441 | given time, and optionally repeating in regular intervals after that. |
988 | .PP |
1442 | .PP |
989 | The timers are based on real time, that is, if you register an event that |
1443 | The timers are based on real time, that is, if you register an event that |
990 | times out after an hour and you reset your system clock to last years |
1444 | times out after an hour and you reset your system clock to January last |
991 | time, it will still time out after (roughly) and hour. \*(L"Roughly\*(R" because |
1445 | year, it will still time out after (roughly) one hour. \*(L"Roughly\*(R" because |
992 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1446 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
993 | monotonic clock option helps a lot here). |
1447 | monotonic clock option helps a lot here). |
|
|
1448 | .PP |
|
|
1449 | The callback is guaranteed to be invoked only \fIafter\fR its timeout has |
|
|
1450 | passed, but if multiple timers become ready during the same loop iteration |
|
|
1451 | then order of execution is undefined. |
|
|
1452 | .PP |
|
|
1453 | \fIBe smart about timeouts\fR |
|
|
1454 | .IX Subsection "Be smart about timeouts" |
|
|
1455 | .PP |
|
|
1456 | Many real-world problems involve some kind of timeout, usually for error |
|
|
1457 | recovery. A typical example is an \s-1HTTP\s0 request \- if the other side hangs, |
|
|
1458 | you want to raise some error after a while. |
|
|
1459 | .PP |
|
|
1460 | What follows are some ways to handle this problem, from obvious and |
|
|
1461 | inefficient to smart and efficient. |
|
|
1462 | .PP |
|
|
1463 | In the following, a 60 second activity timeout is assumed \- a timeout that |
|
|
1464 | gets reset to 60 seconds each time there is activity (e.g. each time some |
|
|
1465 | data or other life sign was received). |
|
|
1466 | .IP "1. Use a timer and stop, reinitialise and start it on activity." 4 |
|
|
1467 | .IX Item "1. Use a timer and stop, reinitialise and start it on activity." |
|
|
1468 | This is the most obvious, but not the most simple way: In the beginning, |
|
|
1469 | start the watcher: |
|
|
1470 | .Sp |
|
|
1471 | .Vb 2 |
|
|
1472 | \& ev_timer_init (timer, callback, 60., 0.); |
|
|
1473 | \& ev_timer_start (loop, timer); |
|
|
1474 | .Ve |
|
|
1475 | .Sp |
|
|
1476 | Then, each time there is some activity, \f(CW\*(C`ev_timer_stop\*(C'\fR it, initialise it |
|
|
1477 | and start it again: |
|
|
1478 | .Sp |
|
|
1479 | .Vb 3 |
|
|
1480 | \& ev_timer_stop (loop, timer); |
|
|
1481 | \& ev_timer_set (timer, 60., 0.); |
|
|
1482 | \& ev_timer_start (loop, timer); |
|
|
1483 | .Ve |
|
|
1484 | .Sp |
|
|
1485 | This is relatively simple to implement, but means that each time there is |
|
|
1486 | some activity, libev will first have to remove the timer from its internal |
|
|
1487 | data structure and then add it again. Libev tries to be fast, but it's |
|
|
1488 | still not a constant-time operation. |
|
|
1489 | .ie n .IP "2. Use a timer and re-start it with ""ev_timer_again"" inactivity." 4 |
|
|
1490 | .el .IP "2. Use a timer and re-start it with \f(CWev_timer_again\fR inactivity." 4 |
|
|
1491 | .IX Item "2. Use a timer and re-start it with ev_timer_again inactivity." |
|
|
1492 | This is the easiest way, and involves using \f(CW\*(C`ev_timer_again\*(C'\fR instead of |
|
|
1493 | \&\f(CW\*(C`ev_timer_start\*(C'\fR. |
|
|
1494 | .Sp |
|
|
1495 | To implement this, configure an \f(CW\*(C`ev_timer\*(C'\fR with a \f(CW\*(C`repeat\*(C'\fR value |
|
|
1496 | of \f(CW60\fR and then call \f(CW\*(C`ev_timer_again\*(C'\fR at start and each time you |
|
|
1497 | successfully read or write some data. If you go into an idle state where |
|
|
1498 | you do not expect data to travel on the socket, you can \f(CW\*(C`ev_timer_stop\*(C'\fR |
|
|
1499 | the timer, and \f(CW\*(C`ev_timer_again\*(C'\fR will automatically restart it if need be. |
|
|
1500 | .Sp |
|
|
1501 | That means you can ignore both the \f(CW\*(C`ev_timer_start\*(C'\fR function and the |
|
|
1502 | \&\f(CW\*(C`after\*(C'\fR argument to \f(CW\*(C`ev_timer_set\*(C'\fR, and only ever use the \f(CW\*(C`repeat\*(C'\fR |
|
|
1503 | member and \f(CW\*(C`ev_timer_again\*(C'\fR. |
|
|
1504 | .Sp |
|
|
1505 | At start: |
|
|
1506 | .Sp |
|
|
1507 | .Vb 3 |
|
|
1508 | \& ev_timer_init (timer, callback); |
|
|
1509 | \& timer\->repeat = 60.; |
|
|
1510 | \& ev_timer_again (loop, timer); |
|
|
1511 | .Ve |
|
|
1512 | .Sp |
|
|
1513 | Each time there is some activity: |
|
|
1514 | .Sp |
|
|
1515 | .Vb 1 |
|
|
1516 | \& ev_timer_again (loop, timer); |
|
|
1517 | .Ve |
|
|
1518 | .Sp |
|
|
1519 | It is even possible to change the time-out on the fly, regardless of |
|
|
1520 | whether the watcher is active or not: |
|
|
1521 | .Sp |
|
|
1522 | .Vb 2 |
|
|
1523 | \& timer\->repeat = 30.; |
|
|
1524 | \& ev_timer_again (loop, timer); |
|
|
1525 | .Ve |
|
|
1526 | .Sp |
|
|
1527 | This is slightly more efficient then stopping/starting the timer each time |
|
|
1528 | you want to modify its timeout value, as libev does not have to completely |
|
|
1529 | remove and re-insert the timer from/into its internal data structure. |
|
|
1530 | .Sp |
|
|
1531 | It is, however, even simpler than the \*(L"obvious\*(R" way to do it. |
|
|
1532 | .IP "3. Let the timer time out, but then re-arm it as required." 4 |
|
|
1533 | .IX Item "3. Let the timer time out, but then re-arm it as required." |
|
|
1534 | This method is more tricky, but usually most efficient: Most timeouts are |
|
|
1535 | relatively long compared to the intervals between other activity \- in |
|
|
1536 | our example, within 60 seconds, there are usually many I/O events with |
|
|
1537 | associated activity resets. |
|
|
1538 | .Sp |
|
|
1539 | In this case, it would be more efficient to leave the \f(CW\*(C`ev_timer\*(C'\fR alone, |
|
|
1540 | but remember the time of last activity, and check for a real timeout only |
|
|
1541 | within the callback: |
|
|
1542 | .Sp |
|
|
1543 | .Vb 1 |
|
|
1544 | \& ev_tstamp last_activity; // time of last activity |
|
|
1545 | \& |
|
|
1546 | \& static void |
|
|
1547 | \& callback (EV_P_ ev_timer *w, int revents) |
|
|
1548 | \& { |
|
|
1549 | \& ev_tstamp now = ev_now (EV_A); |
|
|
1550 | \& ev_tstamp timeout = last_activity + 60.; |
|
|
1551 | \& |
|
|
1552 | \& // if last_activity + 60. is older than now, we did time out |
|
|
1553 | \& if (timeout < now) |
|
|
1554 | \& { |
|
|
1555 | \& // timeout occured, take action |
|
|
1556 | \& } |
|
|
1557 | \& else |
|
|
1558 | \& { |
|
|
1559 | \& // callback was invoked, but there was some activity, re\-arm |
|
|
1560 | \& // the watcher to fire in last_activity + 60, which is |
|
|
1561 | \& // guaranteed to be in the future, so "again" is positive: |
|
|
1562 | \& w\->again = timeout \- now; |
|
|
1563 | \& ev_timer_again (EV_A_ w); |
|
|
1564 | \& } |
|
|
1565 | \& } |
|
|
1566 | .Ve |
|
|
1567 | .Sp |
|
|
1568 | To summarise the callback: first calculate the real timeout (defined |
|
|
1569 | as \*(L"60 seconds after the last activity\*(R"), then check if that time has |
|
|
1570 | been reached, which means something \fIdid\fR, in fact, time out. Otherwise |
|
|
1571 | the callback was invoked too early (\f(CW\*(C`timeout\*(C'\fR is in the future), so |
|
|
1572 | re-schedule the timer to fire at that future time, to see if maybe we have |
|
|
1573 | a timeout then. |
|
|
1574 | .Sp |
|
|
1575 | Note how \f(CW\*(C`ev_timer_again\*(C'\fR is used, taking advantage of the |
|
|
1576 | \&\f(CW\*(C`ev_timer_again\*(C'\fR optimisation when the timer is already running. |
|
|
1577 | .Sp |
|
|
1578 | This scheme causes more callback invocations (about one every 60 seconds |
|
|
1579 | minus half the average time between activity), but virtually no calls to |
|
|
1580 | libev to change the timeout. |
|
|
1581 | .Sp |
|
|
1582 | To start the timer, simply initialise the watcher and set \f(CW\*(C`last_activity\*(C'\fR |
|
|
1583 | to the current time (meaning we just have some activity :), then call the |
|
|
1584 | callback, which will \*(L"do the right thing\*(R" and start the timer: |
|
|
1585 | .Sp |
|
|
1586 | .Vb 3 |
|
|
1587 | \& ev_timer_init (timer, callback); |
|
|
1588 | \& last_activity = ev_now (loop); |
|
|
1589 | \& callback (loop, timer, EV_TIMEOUT); |
|
|
1590 | .Ve |
|
|
1591 | .Sp |
|
|
1592 | And when there is some activity, simply store the current time in |
|
|
1593 | \&\f(CW\*(C`last_activity\*(C'\fR, no libev calls at all: |
|
|
1594 | .Sp |
|
|
1595 | .Vb 1 |
|
|
1596 | \& last_actiivty = ev_now (loop); |
|
|
1597 | .Ve |
|
|
1598 | .Sp |
|
|
1599 | This technique is slightly more complex, but in most cases where the |
|
|
1600 | time-out is unlikely to be triggered, much more efficient. |
|
|
1601 | .Sp |
|
|
1602 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
|
|
1603 | callback :) \- just change the timeout and invoke the callback, which will |
|
|
1604 | fix things for you. |
|
|
1605 | .IP "4. Wee, just use a double-linked list for your timeouts." 4 |
|
|
1606 | .IX Item "4. Wee, just use a double-linked list for your timeouts." |
|
|
1607 | If there is not one request, but many thousands (millions...), all |
|
|
1608 | employing some kind of timeout with the same timeout value, then one can |
|
|
1609 | do even better: |
|
|
1610 | .Sp |
|
|
1611 | When starting the timeout, calculate the timeout value and put the timeout |
|
|
1612 | at the \fIend\fR of the list. |
|
|
1613 | .Sp |
|
|
1614 | Then use an \f(CW\*(C`ev_timer\*(C'\fR to fire when the timeout at the \fIbeginning\fR of |
|
|
1615 | the list is expected to fire (for example, using the technique #3). |
|
|
1616 | .Sp |
|
|
1617 | When there is some activity, remove the timer from the list, recalculate |
|
|
1618 | the timeout, append it to the end of the list again, and make sure to |
|
|
1619 | update the \f(CW\*(C`ev_timer\*(C'\fR if it was taken from the beginning of the list. |
|
|
1620 | .Sp |
|
|
1621 | This way, one can manage an unlimited number of timeouts in O(1) time for |
|
|
1622 | starting, stopping and updating the timers, at the expense of a major |
|
|
1623 | complication, and having to use a constant timeout. The constant timeout |
|
|
1624 | ensures that the list stays sorted. |
|
|
1625 | .PP |
|
|
1626 | So which method the best? |
|
|
1627 | .PP |
|
|
1628 | Method #2 is a simple no-brain-required solution that is adequate in most |
|
|
1629 | situations. Method #3 requires a bit more thinking, but handles many cases |
|
|
1630 | better, and isn't very complicated either. In most case, choosing either |
|
|
1631 | one is fine, with #3 being better in typical situations. |
|
|
1632 | .PP |
|
|
1633 | Method #1 is almost always a bad idea, and buys you nothing. Method #4 is |
|
|
1634 | rather complicated, but extremely efficient, something that really pays |
|
|
1635 | off after the first million or so of active timers, i.e. it's usually |
|
|
1636 | overkill :) |
|
|
1637 | .PP |
|
|
1638 | \fIThe special problem of time updates\fR |
|
|
1639 | .IX Subsection "The special problem of time updates" |
|
|
1640 | .PP |
|
|
1641 | Establishing the current time is a costly operation (it usually takes at |
|
|
1642 | least two system calls): \s-1EV\s0 therefore updates its idea of the current |
|
|
1643 | time only before and after \f(CW\*(C`ev_loop\*(C'\fR collects new events, which causes a |
|
|
1644 | growing difference between \f(CW\*(C`ev_now ()\*(C'\fR and \f(CW\*(C`ev_time ()\*(C'\fR when handling |
|
|
1645 | lots of events in one iteration. |
994 | .PP |
1646 | .PP |
995 | The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR |
1647 | The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR |
996 | time. This is usually the right thing as this timestamp refers to the time |
1648 | time. This is usually the right thing as this timestamp refers to the time |
997 | of the event triggering whatever timeout you are modifying/starting. If |
1649 | of the event triggering whatever timeout you are modifying/starting. If |
998 | you suspect event processing to be delayed and you \fIneed\fR to base the timeout |
1650 | you suspect event processing to be delayed and you \fIneed\fR to base the |
999 | on the current time, use something like this to adjust for this: |
1651 | timeout on the current time, use something like this to adjust for this: |
1000 | .PP |
1652 | .PP |
1001 | .Vb 1 |
1653 | .Vb 1 |
1002 | \& ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
1654 | \& ev_timer_set (&timer, after + ev_now () \- ev_time (), 0.); |
1003 | .Ve |
1655 | .Ve |
1004 | .PP |
1656 | .PP |
1005 | The callback is guarenteed to be invoked only when its timeout has passed, |
1657 | If the event loop is suspended for a long time, you can also force an |
1006 | but if multiple timers become ready during the same loop iteration then |
1658 | update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update |
1007 | order of execution is undefined. |
1659 | ()\*(C'\fR. |
|
|
1660 | .PP |
|
|
1661 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
1662 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1008 | .IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4 |
1663 | .IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4 |
1009 | .IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" |
1664 | .IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" |
1010 | .PD 0 |
1665 | .PD 0 |
1011 | .IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4 |
1666 | .IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4 |
1012 | .IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" |
1667 | .IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" |
1013 | .PD |
1668 | .PD |
1014 | Configure the timer to trigger after \f(CW\*(C`after\*(C'\fR seconds. If \f(CW\*(C`repeat\*(C'\fR is |
1669 | Configure the timer to trigger after \f(CW\*(C`after\*(C'\fR seconds. If \f(CW\*(C`repeat\*(C'\fR |
1015 | \&\f(CW0.\fR, then it will automatically be stopped. If it is positive, then the |
1670 | is \f(CW0.\fR, then it will automatically be stopped once the timeout is |
1016 | timer will automatically be configured to trigger again \f(CW\*(C`repeat\*(C'\fR seconds |
1671 | reached. If it is positive, then the timer will automatically be |
1017 | later, again, and again, until stopped manually. |
1672 | configured to trigger again \f(CW\*(C`repeat\*(C'\fR seconds later, again, and again, |
|
|
1673 | until stopped manually. |
1018 | .Sp |
1674 | .Sp |
1019 | The timer itself will do a best-effort at avoiding drift, that is, if you |
1675 | The timer itself will do a best-effort at avoiding drift, that is, if |
1020 | configure a timer to trigger every 10 seconds, then it will trigger at |
1676 | you configure a timer to trigger every 10 seconds, then it will normally |
1021 | exactly 10 second intervals. If, however, your program cannot keep up with |
1677 | trigger at exactly 10 second intervals. If, however, your program cannot |
1022 | the timer (because it takes longer than those 10 seconds to do stuff) the |
1678 | keep up with the timer (because it takes longer than those 10 seconds to |
1023 | timer will not fire more than once per event loop iteration. |
1679 | do stuff) the timer will not fire more than once per event loop iteration. |
1024 | .IP "ev_timer_again (loop)" 4 |
1680 | .IP "ev_timer_again (loop, ev_timer *)" 4 |
1025 | .IX Item "ev_timer_again (loop)" |
1681 | .IX Item "ev_timer_again (loop, ev_timer *)" |
1026 | This will act as if the timer timed out and restart it again if it is |
1682 | This will act as if the timer timed out and restart it again if it is |
1027 | repeating. The exact semantics are: |
1683 | repeating. The exact semantics are: |
1028 | .Sp |
1684 | .Sp |
|
|
1685 | If the timer is pending, its pending status is cleared. |
|
|
1686 | .Sp |
1029 | If the timer is started but nonrepeating, stop it. |
1687 | If the timer is started but non-repeating, stop it (as if it timed out). |
1030 | .Sp |
1688 | .Sp |
1031 | If the timer is repeating, either start it if necessary (with the repeat |
1689 | If the timer is repeating, either start it if necessary (with the |
1032 | value), or reset the running timer to the repeat value. |
1690 | \&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value. |
1033 | .Sp |
1691 | .Sp |
1034 | This sounds a bit complicated, but here is a useful and typical |
1692 | This sounds a bit complicated, see \*(L"Be smart about timeouts\*(R", above, for a |
1035 | example: Imagine you have a tcp connection and you want a so-called |
1693 | usage example. |
1036 | idle timeout, that is, you want to be called when there have been, |
|
|
1037 | say, 60 seconds of inactivity on the socket. The easiest way to do |
|
|
1038 | 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 |
|
|
1039 | \&\f(CW\*(C`ev_timer_again\*(C'\fR each time you successfully read or write some data. If |
|
|
1040 | you go into an idle state where you do not expect data to travel on the |
|
|
1041 | socket, you can stop the timer, and again will automatically restart it if |
|
|
1042 | need be. |
|
|
1043 | .Sp |
|
|
1044 | You can also ignore the \f(CW\*(C`after\*(C'\fR value and \f(CW\*(C`ev_timer_start\*(C'\fR altogether |
|
|
1045 | and only ever use the \f(CW\*(C`repeat\*(C'\fR value: |
|
|
1046 | .Sp |
|
|
1047 | .Vb 8 |
|
|
1048 | \& ev_timer_init (timer, callback, 0., 5.); |
|
|
1049 | \& ev_timer_again (loop, timer); |
|
|
1050 | \& ... |
|
|
1051 | \& timer->again = 17.; |
|
|
1052 | \& ev_timer_again (loop, timer); |
|
|
1053 | \& ... |
|
|
1054 | \& timer->again = 10.; |
|
|
1055 | \& ev_timer_again (loop, timer); |
|
|
1056 | .Ve |
|
|
1057 | .Sp |
|
|
1058 | This is more efficient then stopping/starting the timer eahc time you want |
|
|
1059 | to modify its timeout value. |
|
|
1060 | .IP "ev_tstamp repeat [read\-write]" 4 |
1694 | .IP "ev_tstamp repeat [read\-write]" 4 |
1061 | .IX Item "ev_tstamp repeat [read-write]" |
1695 | .IX Item "ev_tstamp repeat [read-write]" |
1062 | The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out |
1696 | The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out |
1063 | or \f(CW\*(C`ev_timer_again\*(C'\fR is called and determines the next timeout (if any), |
1697 | or \f(CW\*(C`ev_timer_again\*(C'\fR is called, and determines the next timeout (if any), |
1064 | which is also when any modifications are taken into account. |
1698 | which is also when any modifications are taken into account. |
1065 | .PP |
1699 | .PP |
|
|
1700 | \fIExamples\fR |
|
|
1701 | .IX Subsection "Examples" |
|
|
1702 | .PP |
1066 | Example: create a timer that fires after 60 seconds. |
1703 | Example: Create a timer that fires after 60 seconds. |
1067 | .PP |
1704 | .PP |
1068 | .Vb 5 |
1705 | .Vb 5 |
1069 | \& static void |
1706 | \& static void |
1070 | \& one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1707 | \& one_minute_cb (struct ev_loop *loop, ev_timer *w, int revents) |
1071 | \& { |
1708 | \& { |
1072 | \& .. one minute over, w is actually stopped right here |
1709 | \& .. one minute over, w is actually stopped right here |
1073 | \& } |
1710 | \& } |
1074 | .Ve |
1711 | \& |
1075 | .PP |
|
|
1076 | .Vb 3 |
|
|
1077 | \& struct ev_timer mytimer; |
1712 | \& ev_timer mytimer; |
1078 | \& ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
1713 | \& ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
1079 | \& ev_timer_start (loop, &mytimer); |
1714 | \& ev_timer_start (loop, &mytimer); |
1080 | .Ve |
1715 | .Ve |
1081 | .PP |
1716 | .PP |
1082 | Example: create a timeout timer that times out after 10 seconds of |
1717 | Example: Create a timeout timer that times out after 10 seconds of |
1083 | inactivity. |
1718 | inactivity. |
1084 | .PP |
1719 | .PP |
1085 | .Vb 5 |
1720 | .Vb 5 |
1086 | \& static void |
1721 | \& static void |
1087 | \& timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1722 | \& timeout_cb (struct ev_loop *loop, ev_timer *w, int revents) |
1088 | \& { |
1723 | \& { |
1089 | \& .. ten seconds without any activity |
1724 | \& .. ten seconds without any activity |
1090 | \& } |
1725 | \& } |
1091 | .Ve |
1726 | \& |
1092 | .PP |
|
|
1093 | .Vb 4 |
|
|
1094 | \& struct ev_timer mytimer; |
1727 | \& ev_timer mytimer; |
1095 | \& ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1728 | \& ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1096 | \& ev_timer_again (&mytimer); /* start timer */ |
1729 | \& ev_timer_again (&mytimer); /* start timer */ |
1097 | \& ev_loop (loop, 0); |
1730 | \& ev_loop (loop, 0); |
1098 | .Ve |
1731 | \& |
1099 | .PP |
|
|
1100 | .Vb 3 |
|
|
1101 | \& // and in some piece of code that gets executed on any "activity": |
1732 | \& // and in some piece of code that gets executed on any "activity": |
1102 | \& // reset the timeout to start ticking again at 10 seconds |
1733 | \& // reset the timeout to start ticking again at 10 seconds |
1103 | \& ev_timer_again (&mytimer); |
1734 | \& ev_timer_again (&mytimer); |
1104 | .Ve |
1735 | .Ve |
1105 | .ie n .Sh """ev_periodic"" \- to cron or not to cron?" |
1736 | .ie n .Sh """ev_periodic"" \- to cron or not to cron?" |
1106 | .el .Sh "\f(CWev_periodic\fP \- to cron or not to cron?" |
1737 | .el .Sh "\f(CWev_periodic\fP \- to cron or not to cron?" |
1107 | .IX Subsection "ev_periodic - to cron or not to cron?" |
1738 | .IX Subsection "ev_periodic - to cron or not to cron?" |
1108 | Periodic watchers are also timers of a kind, but they are very versatile |
1739 | Periodic watchers are also timers of a kind, but they are very versatile |
1109 | (and unfortunately a bit complex). |
1740 | (and unfortunately a bit complex). |
1110 | .PP |
1741 | .PP |
1111 | Unlike \f(CW\*(C`ev_timer\*(C'\fR's, they are not based on real time (or relative time) |
1742 | Unlike \f(CW\*(C`ev_timer\*(C'\fR's, they are not based on real time (or relative time) |
1112 | but on wallclock time (absolute time). You can tell a periodic watcher |
1743 | but on wall clock time (absolute time). You can tell a periodic watcher |
1113 | to trigger \*(L"at\*(R" some specific point in time. For example, if you tell a |
1744 | to trigger after some specific point in time. For example, if you tell a |
1114 | periodic watcher to trigger in 10 seconds (by specifiying e.g. \f(CW\*(C`ev_now () |
1745 | periodic watcher to trigger in 10 seconds (by specifying e.g. \f(CW\*(C`ev_now () |
1115 | + 10.\*(C'\fR) and then reset your system clock to the last year, then it will |
1746 | + 10.\*(C'\fR, that is, an absolute time not a delay) and then reset your system |
|
|
1747 | clock to January of the previous year, then it will take more than year |
1116 | take a year to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would trigger |
1748 | to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would still trigger |
1117 | roughly 10 seconds later and of course not if you reset your system time |
1749 | roughly 10 seconds later as it uses a relative timeout). |
1118 | again). |
|
|
1119 | .PP |
1750 | .PP |
1120 | They can also be used to implement vastly more complex timers, such as |
1751 | \&\f(CW\*(C`ev_periodic\*(C'\fRs can also be used to implement vastly more complex timers, |
1121 | triggering an event on eahc midnight, local time. |
1752 | such as triggering an event on each \*(L"midnight, local time\*(R", or other |
|
|
1753 | complicated rules. |
1122 | .PP |
1754 | .PP |
1123 | As with timers, the callback is guarenteed to be invoked only when the |
1755 | As with timers, the callback is guaranteed to be invoked only when the |
1124 | time (\f(CW\*(C`at\*(C'\fR) has been passed, but if multiple periodic timers become ready |
1756 | time (\f(CW\*(C`at\*(C'\fR) has passed, but if multiple periodic timers become ready |
1125 | during the same loop iteration then order of execution is undefined. |
1757 | during the same loop iteration, then order of execution is undefined. |
|
|
1758 | .PP |
|
|
1759 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
1760 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1126 | .IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4 |
1761 | .IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4 |
1127 | .IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" |
1762 | .IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" |
1128 | .PD 0 |
1763 | .PD 0 |
1129 | .IP "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 4 |
1764 | .IP "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 4 |
1130 | .IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" |
1765 | .IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" |
1131 | .PD |
1766 | .PD |
1132 | Lots of arguments, lets sort it out... There are basically three modes of |
1767 | Lots of arguments, lets sort it out... There are basically three modes of |
1133 | operation, and we will explain them from simplest to complex: |
1768 | operation, and we will explain them from simplest to most complex: |
1134 | .RS 4 |
1769 | .RS 4 |
|
|
1770 | .IP "\(bu" 4 |
1135 | .IP "* absolute timer (interval = reschedule_cb = 0)" 4 |
1771 | absolute timer (at = time, interval = reschedule_cb = 0) |
1136 | .IX Item "absolute timer (interval = reschedule_cb = 0)" |
1772 | .Sp |
1137 | In this configuration the watcher triggers an event at the wallclock time |
1773 | In this configuration the watcher triggers an event after the wall clock |
1138 | \&\f(CW\*(C`at\*(C'\fR and doesn't repeat. It will not adjust when a time jump occurs, |
1774 | time \f(CW\*(C`at\*(C'\fR has passed. It will not repeat and will not adjust when a time |
1139 | that is, if it is to be run at January 1st 2011 then it will run when the |
1775 | jump occurs, that is, if it is to be run at January 1st 2011 then it will |
1140 | system time reaches or surpasses this time. |
1776 | only run when the system clock reaches or surpasses this time. |
|
|
1777 | .IP "\(bu" 4 |
1141 | .IP "* non-repeating interval timer (interval > 0, reschedule_cb = 0)" 4 |
1778 | repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
1142 | .IX Item "non-repeating interval timer (interval > 0, reschedule_cb = 0)" |
1779 | .Sp |
1143 | In this mode the watcher will always be scheduled to time out at the next |
1780 | In this mode the watcher will always be scheduled to time out at the next |
1144 | \&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N) and then repeat, regardless |
1781 | \&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N, which can also be negative) |
1145 | of any time jumps. |
1782 | and then repeat, regardless of any time jumps. |
1146 | .Sp |
1783 | .Sp |
1147 | This can be used to create timers that do not drift with respect to system |
1784 | This can be used to create timers that do not drift with respect to the |
1148 | time: |
1785 | system clock, for example, here is a \f(CW\*(C`ev_periodic\*(C'\fR that triggers each |
|
|
1786 | hour, on the hour: |
1149 | .Sp |
1787 | .Sp |
1150 | .Vb 1 |
1788 | .Vb 1 |
1151 | \& ev_periodic_set (&periodic, 0., 3600., 0); |
1789 | \& ev_periodic_set (&periodic, 0., 3600., 0); |
1152 | .Ve |
1790 | .Ve |
1153 | .Sp |
1791 | .Sp |
1154 | This doesn't mean there will always be 3600 seconds in between triggers, |
1792 | This doesn't mean there will always be 3600 seconds in between triggers, |
1155 | but only that the the callback will be called when the system time shows a |
1793 | but only that the callback will be called when the system time shows a |
1156 | full hour (\s-1UTC\s0), or more correctly, when the system time is evenly divisible |
1794 | full hour (\s-1UTC\s0), or more correctly, when the system time is evenly divisible |
1157 | by 3600. |
1795 | by 3600. |
1158 | .Sp |
1796 | .Sp |
1159 | Another way to think about it (for the mathematically inclined) is that |
1797 | Another way to think about it (for the mathematically inclined) is that |
1160 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
1798 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
1161 | time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps. |
1799 | time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps. |
1162 | .IP "* manual reschedule mode (reschedule_cb = callback)" 4 |
1800 | .Sp |
1163 | .IX Item "manual reschedule mode (reschedule_cb = callback)" |
1801 | For numerical stability it is preferable that the \f(CW\*(C`at\*(C'\fR value is near |
|
|
1802 | \&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for |
|
|
1803 | this value, and in fact is often specified as zero. |
|
|
1804 | .Sp |
|
|
1805 | Note also that there is an upper limit to how often a timer can fire (\s-1CPU\s0 |
|
|
1806 | speed for example), so if \f(CW\*(C`interval\*(C'\fR is very small then timing stability |
|
|
1807 | will of course deteriorate. Libev itself tries to be exact to be about one |
|
|
1808 | millisecond (if the \s-1OS\s0 supports it and the machine is fast enough). |
|
|
1809 | .IP "\(bu" 4 |
|
|
1810 | manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
|
|
1811 | .Sp |
1164 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being |
1812 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being |
1165 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1813 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1166 | reschedule callback will be called with the watcher as first, and the |
1814 | reschedule callback will be called with the watcher as first, and the |
1167 | current time as second argument. |
1815 | current time as second argument. |
1168 | .Sp |
1816 | .Sp |
1169 | \&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, |
1817 | \&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, |
1170 | ever, or make any event loop modifications\fR. If you need to stop it, |
1818 | ever, or make \s-1ANY\s0 event loop modifications whatsoever\fR. |
1171 | return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop it afterwards (e.g. by |
|
|
1172 | starting a prepare watcher). |
|
|
1173 | .Sp |
1819 | .Sp |
|
|
1820 | If you need to stop it, return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop |
|
|
1821 | it afterwards (e.g. by starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is the |
|
|
1822 | only event loop modification you are allowed to do). |
|
|
1823 | .Sp |
1174 | Its prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1824 | The callback prototype is \f(CW\*(C`ev_tstamp (*reschedule_cb)(ev_periodic |
1175 | ev_tstamp now)\*(C'\fR, e.g.: |
1825 | *w, ev_tstamp now)\*(C'\fR, e.g.: |
1176 | .Sp |
1826 | .Sp |
1177 | .Vb 4 |
1827 | .Vb 5 |
|
|
1828 | \& static ev_tstamp |
1178 | \& static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
1829 | \& my_rescheduler (ev_periodic *w, ev_tstamp now) |
1179 | \& { |
1830 | \& { |
1180 | \& return now + 60.; |
1831 | \& return now + 60.; |
1181 | \& } |
1832 | \& } |
1182 | .Ve |
1833 | .Ve |
1183 | .Sp |
1834 | .Sp |
1184 | It must return the next time to trigger, based on the passed time value |
1835 | It must return the next time to trigger, based on the passed time value |
1185 | (that is, the lowest time value larger than to the second argument). It |
1836 | (that is, the lowest time value larger than to the second argument). It |
1186 | will usually be called just before the callback will be triggered, but |
1837 | will usually be called just before the callback will be triggered, but |
1187 | might be called at other times, too. |
1838 | might be called at other times, too. |
1188 | .Sp |
1839 | .Sp |
1189 | \&\s-1NOTE:\s0 \fIThis callback must always return a time that is later than the |
1840 | \&\s-1NOTE:\s0 \fIThis callback must always return a time that is higher than or |
1190 | 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. |
1841 | equal to the passed \f(CI\*(C`now\*(C'\fI value\fR. |
1191 | .Sp |
1842 | .Sp |
1192 | This can be used to create very complex timers, such as a timer that |
1843 | This can be used to create very complex timers, such as a timer that |
1193 | triggers on each midnight, local time. To do this, you would calculate the |
1844 | triggers on \*(L"next midnight, local time\*(R". To do this, you would calculate the |
1194 | next midnight after \f(CW\*(C`now\*(C'\fR and return the timestamp value for this. How |
1845 | next midnight after \f(CW\*(C`now\*(C'\fR and return the timestamp value for this. How |
1195 | you do this is, again, up to you (but it is not trivial, which is the main |
1846 | you do this is, again, up to you (but it is not trivial, which is the main |
1196 | reason I omitted it as an example). |
1847 | reason I omitted it as an example). |
1197 | .RE |
1848 | .RE |
1198 | .RS 4 |
1849 | .RS 4 |
… | |
… | |
1201 | .IX Item "ev_periodic_again (loop, ev_periodic *)" |
1852 | .IX Item "ev_periodic_again (loop, ev_periodic *)" |
1202 | Simply stops and restarts the periodic watcher again. This is only useful |
1853 | Simply stops and restarts the periodic watcher again. This is only useful |
1203 | when you changed some parameters or the reschedule callback would return |
1854 | when you changed some parameters or the reschedule callback would return |
1204 | a different time than the last time it was called (e.g. in a crond like |
1855 | a different time than the last time it was called (e.g. in a crond like |
1205 | program when the crontabs have changed). |
1856 | program when the crontabs have changed). |
|
|
1857 | .IP "ev_tstamp ev_periodic_at (ev_periodic *)" 4 |
|
|
1858 | .IX Item "ev_tstamp ev_periodic_at (ev_periodic *)" |
|
|
1859 | When active, returns the absolute time that the watcher is supposed to |
|
|
1860 | trigger next. |
|
|
1861 | .IP "ev_tstamp offset [read\-write]" 4 |
|
|
1862 | .IX Item "ev_tstamp offset [read-write]" |
|
|
1863 | When repeating, this contains the offset value, otherwise this is the |
|
|
1864 | absolute point in time (the \f(CW\*(C`at\*(C'\fR value passed to \f(CW\*(C`ev_periodic_set\*(C'\fR). |
|
|
1865 | .Sp |
|
|
1866 | Can be modified any time, but changes only take effect when the periodic |
|
|
1867 | timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. |
1206 | .IP "ev_tstamp interval [read\-write]" 4 |
1868 | .IP "ev_tstamp interval [read\-write]" 4 |
1207 | .IX Item "ev_tstamp interval [read-write]" |
1869 | .IX Item "ev_tstamp interval [read-write]" |
1208 | The current interval value. Can be modified any time, but changes only |
1870 | The current interval value. Can be modified any time, but changes only |
1209 | take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being |
1871 | take effect when the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being |
1210 | called. |
1872 | called. |
1211 | .IP "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read\-write]" 4 |
1873 | .IP "ev_tstamp (*reschedule_cb)(ev_periodic *w, ev_tstamp now) [read\-write]" 4 |
1212 | .IX Item "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]" |
1874 | .IX Item "ev_tstamp (*reschedule_cb)(ev_periodic *w, ev_tstamp now) [read-write]" |
1213 | The current reschedule callback, or \f(CW0\fR, if this functionality is |
1875 | The current reschedule callback, or \f(CW0\fR, if this functionality is |
1214 | switched off. Can be changed any time, but changes only take effect when |
1876 | switched off. Can be changed any time, but changes only take effect when |
1215 | the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. |
1877 | the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. |
1216 | .PP |
1878 | .PP |
|
|
1879 | \fIExamples\fR |
|
|
1880 | .IX Subsection "Examples" |
|
|
1881 | .PP |
1217 | Example: call a callback every hour, or, more precisely, whenever the |
1882 | Example: Call a callback every hour, or, more precisely, whenever the |
1218 | system clock is divisible by 3600. The callback invocation times have |
1883 | system time is divisible by 3600. The callback invocation times have |
1219 | potentially a lot of jittering, but good long-term stability. |
1884 | potentially a lot of jitter, but good long-term stability. |
1220 | .PP |
1885 | .PP |
1221 | .Vb 5 |
1886 | .Vb 5 |
1222 | \& static void |
1887 | \& static void |
1223 | \& clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1888 | \& clock_cb (struct ev_loop *loop, ev_io *w, int revents) |
1224 | \& { |
1889 | \& { |
1225 | \& ... its now a full hour (UTC, or TAI or whatever your clock follows) |
1890 | \& ... its now a full hour (UTC, or TAI or whatever your clock follows) |
1226 | \& } |
1891 | \& } |
1227 | .Ve |
1892 | \& |
1228 | .PP |
|
|
1229 | .Vb 3 |
|
|
1230 | \& struct ev_periodic hourly_tick; |
1893 | \& ev_periodic hourly_tick; |
1231 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1894 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1232 | \& ev_periodic_start (loop, &hourly_tick); |
1895 | \& ev_periodic_start (loop, &hourly_tick); |
1233 | .Ve |
1896 | .Ve |
1234 | .PP |
1897 | .PP |
1235 | Example: the same as above, but use a reschedule callback to do it: |
1898 | Example: The same as above, but use a reschedule callback to do it: |
1236 | .PP |
1899 | .PP |
1237 | .Vb 1 |
1900 | .Vb 1 |
1238 | \& #include <math.h> |
1901 | \& #include <math.h> |
1239 | .Ve |
1902 | \& |
1240 | .PP |
|
|
1241 | .Vb 5 |
|
|
1242 | \& static ev_tstamp |
1903 | \& static ev_tstamp |
1243 | \& my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
1904 | \& my_scheduler_cb (ev_periodic *w, ev_tstamp now) |
1244 | \& { |
1905 | \& { |
1245 | \& return fmod (now, 3600.) + 3600.; |
1906 | \& return now + (3600. \- fmod (now, 3600.)); |
1246 | \& } |
1907 | \& } |
1247 | .Ve |
1908 | \& |
1248 | .PP |
|
|
1249 | .Vb 1 |
|
|
1250 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1909 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1251 | .Ve |
1910 | .Ve |
1252 | .PP |
1911 | .PP |
1253 | Example: call a callback every hour, starting now: |
1912 | Example: Call a callback every hour, starting now: |
1254 | .PP |
1913 | .PP |
1255 | .Vb 4 |
1914 | .Vb 4 |
1256 | \& struct ev_periodic hourly_tick; |
1915 | \& ev_periodic hourly_tick; |
1257 | \& ev_periodic_init (&hourly_tick, clock_cb, |
1916 | \& ev_periodic_init (&hourly_tick, clock_cb, |
1258 | \& fmod (ev_now (loop), 3600.), 3600., 0); |
1917 | \& fmod (ev_now (loop), 3600.), 3600., 0); |
1259 | \& ev_periodic_start (loop, &hourly_tick); |
1918 | \& ev_periodic_start (loop, &hourly_tick); |
1260 | .Ve |
1919 | .Ve |
1261 | .ie n .Sh """ev_signal"" \- signal me when a signal gets signalled!" |
1920 | .ie n .Sh """ev_signal"" \- signal me when a signal gets signalled!" |
1262 | .el .Sh "\f(CWev_signal\fP \- signal me when a signal gets signalled!" |
1921 | .el .Sh "\f(CWev_signal\fP \- signal me when a signal gets signalled!" |
1263 | .IX Subsection "ev_signal - signal me when a signal gets signalled!" |
1922 | .IX Subsection "ev_signal - signal me when a signal gets signalled!" |
1264 | Signal watchers will trigger an event when the process receives a specific |
1923 | Signal watchers will trigger an event when the process receives a specific |
1265 | signal one or more times. Even though signals are very asynchronous, libev |
1924 | signal one or more times. Even though signals are very asynchronous, libev |
1266 | will try it's best to deliver signals synchronously, i.e. as part of the |
1925 | will try it's best to deliver signals synchronously, i.e. as part of the |
1267 | normal event processing, like any other event. |
1926 | normal event processing, like any other event. |
1268 | .PP |
1927 | .PP |
|
|
1928 | If you want signals asynchronously, just use \f(CW\*(C`sigaction\*(C'\fR as you would |
|
|
1929 | do without libev and forget about sharing the signal. You can even use |
|
|
1930 | \&\f(CW\*(C`ev_async\*(C'\fR from a signal handler to synchronously wake up an event loop. |
|
|
1931 | .PP |
1269 | You can configure as many watchers as you like per signal. Only when the |
1932 | You can configure as many watchers as you like per signal. Only when the |
1270 | first watcher gets started will libev actually register a signal watcher |
1933 | first watcher gets started will libev actually register a signal handler |
1271 | with the kernel (thus it coexists with your own signal handlers as long |
1934 | with the kernel (thus it coexists with your own signal handlers as long as |
1272 | as you don't register any with libev). Similarly, when the last signal |
1935 | you don't register any with libev for the same signal). Similarly, when |
1273 | watcher for a signal is stopped libev will reset the signal handler to |
1936 | the last signal watcher for a signal is stopped, libev will reset the |
1274 | \&\s-1SIG_DFL\s0 (regardless of what it was set to before). |
1937 | signal handler to \s-1SIG_DFL\s0 (regardless of what it was set to before). |
|
|
1938 | .PP |
|
|
1939 | If possible and supported, libev will install its handlers with |
|
|
1940 | \&\f(CW\*(C`SA_RESTART\*(C'\fR behaviour enabled, so system calls should not be unduly |
|
|
1941 | interrupted. If you have a problem with system calls getting interrupted by |
|
|
1942 | signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher and unblock |
|
|
1943 | them in an \f(CW\*(C`ev_prepare\*(C'\fR watcher. |
|
|
1944 | .PP |
|
|
1945 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
1946 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1275 | .IP "ev_signal_init (ev_signal *, callback, int signum)" 4 |
1947 | .IP "ev_signal_init (ev_signal *, callback, int signum)" 4 |
1276 | .IX Item "ev_signal_init (ev_signal *, callback, int signum)" |
1948 | .IX Item "ev_signal_init (ev_signal *, callback, int signum)" |
1277 | .PD 0 |
1949 | .PD 0 |
1278 | .IP "ev_signal_set (ev_signal *, int signum)" 4 |
1950 | .IP "ev_signal_set (ev_signal *, int signum)" 4 |
1279 | .IX Item "ev_signal_set (ev_signal *, int signum)" |
1951 | .IX Item "ev_signal_set (ev_signal *, int signum)" |
… | |
… | |
1281 | Configures the watcher to trigger on the given signal number (usually one |
1953 | Configures the watcher to trigger on the given signal number (usually one |
1282 | of the \f(CW\*(C`SIGxxx\*(C'\fR constants). |
1954 | of the \f(CW\*(C`SIGxxx\*(C'\fR constants). |
1283 | .IP "int signum [read\-only]" 4 |
1955 | .IP "int signum [read\-only]" 4 |
1284 | .IX Item "int signum [read-only]" |
1956 | .IX Item "int signum [read-only]" |
1285 | The signal the watcher watches out for. |
1957 | The signal the watcher watches out for. |
|
|
1958 | .PP |
|
|
1959 | \fIExamples\fR |
|
|
1960 | .IX Subsection "Examples" |
|
|
1961 | .PP |
|
|
1962 | Example: Try to exit cleanly on \s-1SIGINT\s0. |
|
|
1963 | .PP |
|
|
1964 | .Vb 5 |
|
|
1965 | \& static void |
|
|
1966 | \& sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
|
|
1967 | \& { |
|
|
1968 | \& ev_unloop (loop, EVUNLOOP_ALL); |
|
|
1969 | \& } |
|
|
1970 | \& |
|
|
1971 | \& ev_signal signal_watcher; |
|
|
1972 | \& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
|
|
1973 | \& ev_signal_start (loop, &signal_watcher); |
|
|
1974 | .Ve |
1286 | .ie n .Sh """ev_child"" \- watch out for process status changes" |
1975 | .ie n .Sh """ev_child"" \- watch out for process status changes" |
1287 | .el .Sh "\f(CWev_child\fP \- watch out for process status changes" |
1976 | .el .Sh "\f(CWev_child\fP \- watch out for process status changes" |
1288 | .IX Subsection "ev_child - watch out for process status changes" |
1977 | .IX Subsection "ev_child - watch out for process status changes" |
1289 | Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to |
1978 | Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to |
1290 | some child status changes (most typically when a child of yours dies). |
1979 | some child status changes (most typically when a child of yours dies or |
|
|
1980 | exits). It is permissible to install a child watcher \fIafter\fR the child |
|
|
1981 | has been forked (which implies it might have already exited), as long |
|
|
1982 | as the event loop isn't entered (or is continued from a watcher), i.e., |
|
|
1983 | forking and then immediately registering a watcher for the child is fine, |
|
|
1984 | but forking and registering a watcher a few event loop iterations later is |
|
|
1985 | not. |
|
|
1986 | .PP |
|
|
1987 | Only the default event loop is capable of handling signals, and therefore |
|
|
1988 | you can only register child watchers in the default event loop. |
|
|
1989 | .PP |
|
|
1990 | \fIProcess Interaction\fR |
|
|
1991 | .IX Subsection "Process Interaction" |
|
|
1992 | .PP |
|
|
1993 | Libev grabs \f(CW\*(C`SIGCHLD\*(C'\fR as soon as the default event loop is |
|
|
1994 | initialised. This is necessary to guarantee proper behaviour even if |
|
|
1995 | the first child watcher is started after the child exits. The occurrence |
|
|
1996 | of \f(CW\*(C`SIGCHLD\*(C'\fR is recorded asynchronously, but child reaping is done |
|
|
1997 | synchronously as part of the event loop processing. Libev always reaps all |
|
|
1998 | children, even ones not watched. |
|
|
1999 | .PP |
|
|
2000 | \fIOverriding the Built-In Processing\fR |
|
|
2001 | .IX Subsection "Overriding the Built-In Processing" |
|
|
2002 | .PP |
|
|
2003 | Libev offers no special support for overriding the built-in child |
|
|
2004 | processing, but if your application collides with libev's default child |
|
|
2005 | handler, you can override it easily by installing your own handler for |
|
|
2006 | \&\f(CW\*(C`SIGCHLD\*(C'\fR after initialising the default loop, and making sure the |
|
|
2007 | default loop never gets destroyed. You are encouraged, however, to use an |
|
|
2008 | event-based approach to child reaping and thus use libev's support for |
|
|
2009 | that, so other libev users can use \f(CW\*(C`ev_child\*(C'\fR watchers freely. |
|
|
2010 | .PP |
|
|
2011 | \fIStopping the Child Watcher\fR |
|
|
2012 | .IX Subsection "Stopping the Child Watcher" |
|
|
2013 | .PP |
|
|
2014 | Currently, the child watcher never gets stopped, even when the |
|
|
2015 | child terminates, so normally one needs to stop the watcher in the |
|
|
2016 | callback. Future versions of libev might stop the watcher automatically |
|
|
2017 | when a child exit is detected. |
|
|
2018 | .PP |
|
|
2019 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
2020 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1291 | .IP "ev_child_init (ev_child *, callback, int pid)" 4 |
2021 | .IP "ev_child_init (ev_child *, callback, int pid, int trace)" 4 |
1292 | .IX Item "ev_child_init (ev_child *, callback, int pid)" |
2022 | .IX Item "ev_child_init (ev_child *, callback, int pid, int trace)" |
1293 | .PD 0 |
2023 | .PD 0 |
1294 | .IP "ev_child_set (ev_child *, int pid)" 4 |
2024 | .IP "ev_child_set (ev_child *, int pid, int trace)" 4 |
1295 | .IX Item "ev_child_set (ev_child *, int pid)" |
2025 | .IX Item "ev_child_set (ev_child *, int pid, int trace)" |
1296 | .PD |
2026 | .PD |
1297 | Configures the watcher to wait for status changes of process \f(CW\*(C`pid\*(C'\fR (or |
2027 | Configures the watcher to wait for status changes of process \f(CW\*(C`pid\*(C'\fR (or |
1298 | \&\fIany\fR process if \f(CW\*(C`pid\*(C'\fR is specified as \f(CW0\fR). The callback can look |
2028 | \&\fIany\fR process if \f(CW\*(C`pid\*(C'\fR is specified as \f(CW0\fR). The callback can look |
1299 | at the \f(CW\*(C`rstatus\*(C'\fR member of the \f(CW\*(C`ev_child\*(C'\fR watcher structure to see |
2029 | at the \f(CW\*(C`rstatus\*(C'\fR member of the \f(CW\*(C`ev_child\*(C'\fR watcher structure to see |
1300 | the status word (use the macros from \f(CW\*(C`sys/wait.h\*(C'\fR and see your systems |
2030 | the status word (use the macros from \f(CW\*(C`sys/wait.h\*(C'\fR and see your systems |
1301 | \&\f(CW\*(C`waitpid\*(C'\fR documentation). The \f(CW\*(C`rpid\*(C'\fR member contains the pid of the |
2031 | \&\f(CW\*(C`waitpid\*(C'\fR documentation). The \f(CW\*(C`rpid\*(C'\fR member contains the pid of the |
1302 | process causing the status change. |
2032 | process causing the status change. \f(CW\*(C`trace\*(C'\fR must be either \f(CW0\fR (only |
|
|
2033 | activate the watcher when the process terminates) or \f(CW1\fR (additionally |
|
|
2034 | activate the watcher when the process is stopped or continued). |
1303 | .IP "int pid [read\-only]" 4 |
2035 | .IP "int pid [read\-only]" 4 |
1304 | .IX Item "int pid [read-only]" |
2036 | .IX Item "int pid [read-only]" |
1305 | The process id this watcher watches out for, or \f(CW0\fR, meaning any process id. |
2037 | The process id this watcher watches out for, or \f(CW0\fR, meaning any process id. |
1306 | .IP "int rpid [read\-write]" 4 |
2038 | .IP "int rpid [read\-write]" 4 |
1307 | .IX Item "int rpid [read-write]" |
2039 | .IX Item "int rpid [read-write]" |
… | |
… | |
1309 | .IP "int rstatus [read\-write]" 4 |
2041 | .IP "int rstatus [read\-write]" 4 |
1310 | .IX Item "int rstatus [read-write]" |
2042 | .IX Item "int rstatus [read-write]" |
1311 | The process exit/trace status caused by \f(CW\*(C`rpid\*(C'\fR (see your systems |
2043 | The process exit/trace status caused by \f(CW\*(C`rpid\*(C'\fR (see your systems |
1312 | \&\f(CW\*(C`waitpid\*(C'\fR and \f(CW\*(C`sys/wait.h\*(C'\fR documentation for details). |
2044 | \&\f(CW\*(C`waitpid\*(C'\fR and \f(CW\*(C`sys/wait.h\*(C'\fR documentation for details). |
1313 | .PP |
2045 | .PP |
1314 | Example: try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0. |
2046 | \fIExamples\fR |
|
|
2047 | .IX Subsection "Examples" |
1315 | .PP |
2048 | .PP |
|
|
2049 | Example: \f(CW\*(C`fork()\*(C'\fR a new process and install a child handler to wait for |
|
|
2050 | its completion. |
|
|
2051 | .PP |
1316 | .Vb 5 |
2052 | .Vb 1 |
|
|
2053 | \& ev_child cw; |
|
|
2054 | \& |
1317 | \& static void |
2055 | \& static void |
1318 | \& sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
2056 | \& child_cb (EV_P_ ev_child *w, int revents) |
1319 | \& { |
2057 | \& { |
1320 | \& ev_unloop (loop, EVUNLOOP_ALL); |
2058 | \& ev_child_stop (EV_A_ w); |
|
|
2059 | \& printf ("process %d exited with status %x\en", w\->rpid, w\->rstatus); |
1321 | \& } |
2060 | \& } |
1322 | .Ve |
2061 | \& |
1323 | .PP |
2062 | \& pid_t pid = fork (); |
1324 | .Vb 3 |
2063 | \& |
1325 | \& struct ev_signal signal_watcher; |
2064 | \& if (pid < 0) |
1326 | \& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2065 | \& // error |
1327 | \& ev_signal_start (loop, &sigint_cb); |
2066 | \& else if (pid == 0) |
|
|
2067 | \& { |
|
|
2068 | \& // the forked child executes here |
|
|
2069 | \& exit (1); |
|
|
2070 | \& } |
|
|
2071 | \& else |
|
|
2072 | \& { |
|
|
2073 | \& ev_child_init (&cw, child_cb, pid, 0); |
|
|
2074 | \& ev_child_start (EV_DEFAULT_ &cw); |
|
|
2075 | \& } |
1328 | .Ve |
2076 | .Ve |
1329 | .ie n .Sh """ev_stat"" \- did the file attributes just change?" |
2077 | .ie n .Sh """ev_stat"" \- did the file attributes just change?" |
1330 | .el .Sh "\f(CWev_stat\fP \- did the file attributes just change?" |
2078 | .el .Sh "\f(CWev_stat\fP \- did the file attributes just change?" |
1331 | .IX Subsection "ev_stat - did the file attributes just change?" |
2079 | .IX Subsection "ev_stat - did the file attributes just change?" |
1332 | This watches a filesystem path for attribute changes. That is, it calls |
2080 | This watches a file system path for attribute changes. That is, it calls |
1333 | \&\f(CW\*(C`stat\*(C'\fR regularly (or when the \s-1OS\s0 says it changed) and sees if it changed |
2081 | \&\f(CW\*(C`stat\*(C'\fR on that path in regular intervals (or when the \s-1OS\s0 says it changed) |
1334 | compared to the last time, invoking the callback if it did. |
2082 | and sees if it changed compared to the last time, invoking the callback if |
|
|
2083 | it did. |
1335 | .PP |
2084 | .PP |
1336 | The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does |
2085 | The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does |
1337 | not exist\*(R" is a status change like any other. The condition \*(L"path does |
2086 | not exist\*(R" is a status change like any other. The condition \*(L"path does |
1338 | not exist\*(R" is signified by the \f(CW\*(C`st_nlink\*(C'\fR field being zero (which is |
2087 | not exist\*(R" is signified by the \f(CW\*(C`st_nlink\*(C'\fR field being zero (which is |
1339 | otherwise always forced to be at least one) and all the other fields of |
2088 | otherwise always forced to be at least one) and all the other fields of |
1340 | the stat buffer having unspecified contents. |
2089 | the stat buffer having unspecified contents. |
1341 | .PP |
2090 | .PP |
1342 | Since there is no standard to do this, the portable implementation simply |
2091 | The path \fImust not\fR end in a slash or contain special components such as |
1343 | calls \f(CW\*(C`stat (2)\*(C'\fR regulalry on the path to see if it changed somehow. You |
2092 | \&\f(CW\*(C`.\*(C'\fR or \f(CW\*(C`..\*(C'\fR. The path \fIshould\fR be absolute: If it is relative and |
1344 | can specify a recommended polling interval for this case. If you specify |
2093 | your working directory changes, then the behaviour is undefined. |
1345 | a polling interval of \f(CW0\fR (highly recommended!) then a \fIsuitable, |
2094 | .PP |
1346 | unspecified default\fR value will be used (which you can expect to be around |
2095 | Since there is no portable change notification interface available, the |
1347 | five seconds, although this might change dynamically). Libev will also |
2096 | portable implementation simply calls \f(CWstat(2)\fR regularly on the path |
1348 | impose a minimum interval which is currently around \f(CW0.1\fR, but thats |
2097 | to see if it changed somehow. You can specify a recommended polling |
1349 | usually overkill. |
2098 | interval for this case. If you specify a polling interval of \f(CW0\fR (highly |
|
|
2099 | recommended!) then a \fIsuitable, unspecified default\fR value will be used |
|
|
2100 | (which you can expect to be around five seconds, although this might |
|
|
2101 | change dynamically). Libev will also impose a minimum interval which is |
|
|
2102 | currently around \f(CW0.1\fR, but that's usually overkill. |
1350 | .PP |
2103 | .PP |
1351 | This watcher type is not meant for massive numbers of stat watchers, |
2104 | This watcher type is not meant for massive numbers of stat watchers, |
1352 | as even with OS-supported change notifications, this can be |
2105 | as even with OS-supported change notifications, this can be |
1353 | resource\-intensive. |
2106 | resource-intensive. |
1354 | .PP |
2107 | .PP |
1355 | At the time of this writing, no specific \s-1OS\s0 backends are implemented, but |
2108 | At the time of this writing, the only OS-specific interface implemented |
1356 | if demand increases, at least a kqueue and inotify backend will be added. |
2109 | is the Linux inotify interface (implementing kqueue support is left as |
|
|
2110 | an exercise for the reader. Note, however, that the author sees no way |
|
|
2111 | of implementing \f(CW\*(C`ev_stat\*(C'\fR semantics with kqueue). |
|
|
2112 | .PP |
|
|
2113 | \fI\s-1ABI\s0 Issues (Largefile Support)\fR |
|
|
2114 | .IX Subsection "ABI Issues (Largefile Support)" |
|
|
2115 | .PP |
|
|
2116 | Libev by default (unless the user overrides this) uses the default |
|
|
2117 | compilation environment, which means that on systems with large file |
|
|
2118 | support disabled by default, you get the 32 bit version of the stat |
|
|
2119 | structure. When using the library from programs that change the \s-1ABI\s0 to |
|
|
2120 | use 64 bit file offsets the programs will fail. In that case you have to |
|
|
2121 | compile libev with the same flags to get binary compatibility. This is |
|
|
2122 | obviously the case with any flags that change the \s-1ABI\s0, but the problem is |
|
|
2123 | most noticeably displayed with ev_stat and large file support. |
|
|
2124 | .PP |
|
|
2125 | The solution for this is to lobby your distribution maker to make large |
|
|
2126 | file interfaces available by default (as e.g. FreeBSD does) and not |
|
|
2127 | optional. Libev cannot simply switch on large file support because it has |
|
|
2128 | to exchange stat structures with application programs compiled using the |
|
|
2129 | default compilation environment. |
|
|
2130 | .PP |
|
|
2131 | \fIInotify and Kqueue\fR |
|
|
2132 | .IX Subsection "Inotify and Kqueue" |
|
|
2133 | .PP |
|
|
2134 | When \f(CW\*(C`inotify (7)\*(C'\fR support has been compiled into libev (generally |
|
|
2135 | only available with Linux 2.6.25 or above due to bugs in earlier |
|
|
2136 | implementations) and present at runtime, it will be used to speed up |
|
|
2137 | change detection where possible. The inotify descriptor will be created |
|
|
2138 | lazily when the first \f(CW\*(C`ev_stat\*(C'\fR watcher is being started. |
|
|
2139 | .PP |
|
|
2140 | Inotify presence does not change the semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers |
|
|
2141 | except that changes might be detected earlier, and in some cases, to avoid |
|
|
2142 | making regular \f(CW\*(C`stat\*(C'\fR calls. Even in the presence of inotify support |
|
|
2143 | there are many cases where libev has to resort to regular \f(CW\*(C`stat\*(C'\fR polling, |
|
|
2144 | but as long as the path exists, libev usually gets away without polling. |
|
|
2145 | .PP |
|
|
2146 | There is no support for kqueue, as apparently it cannot be used to |
|
|
2147 | implement this functionality, due to the requirement of having a file |
|
|
2148 | descriptor open on the object at all times, and detecting renames, unlinks |
|
|
2149 | etc. is difficult. |
|
|
2150 | .PP |
|
|
2151 | \fIThe special problem of stat time resolution\fR |
|
|
2152 | .IX Subsection "The special problem of stat time resolution" |
|
|
2153 | .PP |
|
|
2154 | The \f(CW\*(C`stat ()\*(C'\fR system call only supports full-second resolution portably, |
|
|
2155 | and even on systems where the resolution is higher, most file systems |
|
|
2156 | still only support whole seconds. |
|
|
2157 | .PP |
|
|
2158 | That means that, if the time is the only thing that changes, you can |
|
|
2159 | easily miss updates: on the first update, \f(CW\*(C`ev_stat\*(C'\fR detects a change and |
|
|
2160 | calls your callback, which does something. When there is another update |
|
|
2161 | within the same second, \f(CW\*(C`ev_stat\*(C'\fR will be unable to detect unless the |
|
|
2162 | stat data does change in other ways (e.g. file size). |
|
|
2163 | .PP |
|
|
2164 | The solution to this is to delay acting on a change for slightly more |
|
|
2165 | than a second (or till slightly after the next full second boundary), using |
|
|
2166 | a roughly one-second-delay \f(CW\*(C`ev_timer\*(C'\fR (e.g. \f(CW\*(C`ev_timer_set (w, 0., 1.02); |
|
|
2167 | ev_timer_again (loop, w)\*(C'\fR). |
|
|
2168 | .PP |
|
|
2169 | The \f(CW.02\fR offset is added to work around small timing inconsistencies |
|
|
2170 | of some operating systems (where the second counter of the current time |
|
|
2171 | might be be delayed. One such system is the Linux kernel, where a call to |
|
|
2172 | \&\f(CW\*(C`gettimeofday\*(C'\fR might return a timestamp with a full second later than |
|
|
2173 | a subsequent \f(CW\*(C`time\*(C'\fR call \- if the equivalent of \f(CW\*(C`time ()\*(C'\fR is used to |
|
|
2174 | update file times then there will be a small window where the kernel uses |
|
|
2175 | the previous second to update file times but libev might already execute |
|
|
2176 | the timer callback). |
|
|
2177 | .PP |
|
|
2178 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
2179 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1357 | .IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4 |
2180 | .IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4 |
1358 | .IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" |
2181 | .IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" |
1359 | .PD 0 |
2182 | .PD 0 |
1360 | .IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4 |
2183 | .IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4 |
1361 | .IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" |
2184 | .IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" |
… | |
… | |
1364 | \&\f(CW\*(C`path\*(C'\fR. The \f(CW\*(C`interval\*(C'\fR is a hint on how quickly a change is expected to |
2187 | \&\f(CW\*(C`path\*(C'\fR. The \f(CW\*(C`interval\*(C'\fR is a hint on how quickly a change is expected to |
1365 | be detected and should normally be specified as \f(CW0\fR to let libev choose |
2188 | be detected and should normally be specified as \f(CW0\fR to let libev choose |
1366 | a suitable value. The memory pointed to by \f(CW\*(C`path\*(C'\fR must point to the same |
2189 | a suitable value. The memory pointed to by \f(CW\*(C`path\*(C'\fR must point to the same |
1367 | path for as long as the watcher is active. |
2190 | path for as long as the watcher is active. |
1368 | .Sp |
2191 | .Sp |
1369 | The callback will be receive \f(CW\*(C`EV_STAT\*(C'\fR when a change was detected, |
2192 | The callback will receive an \f(CW\*(C`EV_STAT\*(C'\fR event when a change was detected, |
1370 | relative to the attributes at the time the watcher was started (or the |
2193 | relative to the attributes at the time the watcher was started (or the |
1371 | last change was detected). |
2194 | last change was detected). |
1372 | .IP "ev_stat_stat (ev_stat *)" 4 |
2195 | .IP "ev_stat_stat (loop, ev_stat *)" 4 |
1373 | .IX Item "ev_stat_stat (ev_stat *)" |
2196 | .IX Item "ev_stat_stat (loop, ev_stat *)" |
1374 | Updates the stat buffer immediately with new values. If you change the |
2197 | Updates the stat buffer immediately with new values. If you change the |
1375 | watched path in your callback, you could call this fucntion to avoid |
2198 | watched path in your callback, you could call this function to avoid |
1376 | detecting this change (while introducing a race condition). Can also be |
2199 | detecting this change (while introducing a race condition if you are not |
1377 | useful simply to find out the new values. |
2200 | the only one changing the path). Can also be useful simply to find out the |
|
|
2201 | new values. |
1378 | .IP "ev_statdata attr [read\-only]" 4 |
2202 | .IP "ev_statdata attr [read\-only]" 4 |
1379 | .IX Item "ev_statdata attr [read-only]" |
2203 | .IX Item "ev_statdata attr [read-only]" |
1380 | The most-recently detected attributes of the file. Although the type is of |
2204 | The most-recently detected attributes of the file. Although the type is |
1381 | \&\f(CW\*(C`ev_statdata\*(C'\fR, this is usually the (or one of the) \f(CW\*(C`struct stat\*(C'\fR types |
2205 | \&\f(CW\*(C`ev_statdata\*(C'\fR, this is usually the (or one of the) \f(CW\*(C`struct stat\*(C'\fR types |
|
|
2206 | suitable for your system, but you can only rely on the POSIX-standardised |
1382 | suitable for your system. If the \f(CW\*(C`st_nlink\*(C'\fR member is \f(CW0\fR, then there |
2207 | members to be present. If the \f(CW\*(C`st_nlink\*(C'\fR member is \f(CW0\fR, then there was |
1383 | was some error while \f(CW\*(C`stat\*(C'\fRing the file. |
2208 | some error while \f(CW\*(C`stat\*(C'\fRing the file. |
1384 | .IP "ev_statdata prev [read\-only]" 4 |
2209 | .IP "ev_statdata prev [read\-only]" 4 |
1385 | .IX Item "ev_statdata prev [read-only]" |
2210 | .IX Item "ev_statdata prev [read-only]" |
1386 | The previous attributes of the file. The callback gets invoked whenever |
2211 | The previous attributes of the file. The callback gets invoked whenever |
1387 | \&\f(CW\*(C`prev\*(C'\fR != \f(CW\*(C`attr\*(C'\fR. |
2212 | \&\f(CW\*(C`prev\*(C'\fR != \f(CW\*(C`attr\*(C'\fR, or, more precisely, one or more of these members |
|
|
2213 | 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, |
|
|
2214 | \&\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. |
1388 | .IP "ev_tstamp interval [read\-only]" 4 |
2215 | .IP "ev_tstamp interval [read\-only]" 4 |
1389 | .IX Item "ev_tstamp interval [read-only]" |
2216 | .IX Item "ev_tstamp interval [read-only]" |
1390 | The specified interval. |
2217 | The specified interval. |
1391 | .IP "const char *path [read\-only]" 4 |
2218 | .IP "const char *path [read\-only]" 4 |
1392 | .IX Item "const char *path [read-only]" |
2219 | .IX Item "const char *path [read-only]" |
1393 | The filesystem path that is being watched. |
2220 | The file system path that is being watched. |
|
|
2221 | .PP |
|
|
2222 | \fIExamples\fR |
|
|
2223 | .IX Subsection "Examples" |
1394 | .PP |
2224 | .PP |
1395 | Example: Watch \f(CW\*(C`/etc/passwd\*(C'\fR for attribute changes. |
2225 | Example: Watch \f(CW\*(C`/etc/passwd\*(C'\fR for attribute changes. |
1396 | .PP |
2226 | .PP |
1397 | .Vb 15 |
2227 | .Vb 10 |
1398 | \& static void |
2228 | \& static void |
1399 | \& passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
2229 | \& passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
1400 | \& { |
2230 | \& { |
1401 | \& /* /etc/passwd changed in some way */ |
2231 | \& /* /etc/passwd changed in some way */ |
1402 | \& if (w->attr.st_nlink) |
2232 | \& if (w\->attr.st_nlink) |
1403 | \& { |
2233 | \& { |
1404 | \& printf ("passwd current size %ld\en", (long)w->attr.st_size); |
2234 | \& printf ("passwd current size %ld\en", (long)w\->attr.st_size); |
1405 | \& printf ("passwd current atime %ld\en", (long)w->attr.st_mtime); |
2235 | \& printf ("passwd current atime %ld\en", (long)w\->attr.st_mtime); |
1406 | \& printf ("passwd current mtime %ld\en", (long)w->attr.st_mtime); |
2236 | \& printf ("passwd current mtime %ld\en", (long)w\->attr.st_mtime); |
1407 | \& } |
2237 | \& } |
1408 | \& else |
2238 | \& else |
1409 | \& /* you shalt not abuse printf for puts */ |
2239 | \& /* you shalt not abuse printf for puts */ |
1410 | \& puts ("wow, /etc/passwd is not there, expect problems. " |
2240 | \& puts ("wow, /etc/passwd is not there, expect problems. " |
1411 | \& "if this is windows, they already arrived\en"); |
2241 | \& "if this is windows, they already arrived\en"); |
1412 | \& } |
2242 | \& } |
|
|
2243 | \& |
|
|
2244 | \& ... |
|
|
2245 | \& ev_stat passwd; |
|
|
2246 | \& |
|
|
2247 | \& ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.); |
|
|
2248 | \& ev_stat_start (loop, &passwd); |
1413 | .Ve |
2249 | .Ve |
|
|
2250 | .PP |
|
|
2251 | Example: Like above, but additionally use a one-second delay so we do not |
|
|
2252 | miss updates (however, frequent updates will delay processing, too, so |
|
|
2253 | one might do the work both on \f(CW\*(C`ev_stat\*(C'\fR callback invocation \fIand\fR on |
|
|
2254 | \&\f(CW\*(C`ev_timer\*(C'\fR callback invocation). |
1414 | .PP |
2255 | .PP |
1415 | .Vb 2 |
2256 | .Vb 2 |
|
|
2257 | \& static ev_stat passwd; |
|
|
2258 | \& static ev_timer timer; |
|
|
2259 | \& |
|
|
2260 | \& static void |
|
|
2261 | \& timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
2262 | \& { |
|
|
2263 | \& ev_timer_stop (EV_A_ w); |
|
|
2264 | \& |
|
|
2265 | \& /* now it\*(Aqs one second after the most recent passwd change */ |
|
|
2266 | \& } |
|
|
2267 | \& |
|
|
2268 | \& static void |
|
|
2269 | \& stat_cb (EV_P_ ev_stat *w, int revents) |
|
|
2270 | \& { |
|
|
2271 | \& /* reset the one\-second timer */ |
|
|
2272 | \& ev_timer_again (EV_A_ &timer); |
|
|
2273 | \& } |
|
|
2274 | \& |
1416 | \& ... |
2275 | \& ... |
1417 | \& ev_stat passwd; |
|
|
1418 | .Ve |
|
|
1419 | .PP |
|
|
1420 | .Vb 2 |
|
|
1421 | \& ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
2276 | \& ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
1422 | \& ev_stat_start (loop, &passwd); |
2277 | \& ev_stat_start (loop, &passwd); |
|
|
2278 | \& ev_timer_init (&timer, timer_cb, 0., 1.02); |
1423 | .Ve |
2279 | .Ve |
1424 | .ie n .Sh """ev_idle"" \- when you've got nothing better to do..." |
2280 | .ie n .Sh """ev_idle"" \- when you've got nothing better to do..." |
1425 | .el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..." |
2281 | .el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..." |
1426 | .IX Subsection "ev_idle - when you've got nothing better to do..." |
2282 | .IX Subsection "ev_idle - when you've got nothing better to do..." |
1427 | Idle watchers trigger events when there are no other events are pending |
2283 | Idle watchers trigger events when no other events of the same or higher |
1428 | (prepare, check and other idle watchers do not count). That is, as long |
2284 | priority are pending (prepare, check and other idle watchers do not count |
1429 | as your process is busy handling sockets or timeouts (or even signals, |
2285 | as receiving \*(L"events\*(R"). |
1430 | imagine) it will not be triggered. But when your process is idle all idle |
2286 | .PP |
1431 | watchers are being called again and again, once per event loop iteration \- |
2287 | That is, as long as your process is busy handling sockets or timeouts |
|
|
2288 | (or even signals, imagine) of the same or higher priority it will not be |
|
|
2289 | triggered. But when your process is idle (or only lower-priority watchers |
|
|
2290 | are pending), the idle watchers are being called once per event loop |
1432 | until stopped, that is, or your process receives more events and becomes |
2291 | iteration \- until stopped, that is, or your process receives more events |
1433 | busy. |
2292 | and becomes busy again with higher priority stuff. |
1434 | .PP |
2293 | .PP |
1435 | The most noteworthy effect is that as long as any idle watchers are |
2294 | The most noteworthy effect is that as long as any idle watchers are |
1436 | active, the process will not block when waiting for new events. |
2295 | active, the process will not block when waiting for new events. |
1437 | .PP |
2296 | .PP |
1438 | Apart from keeping your process non-blocking (which is a useful |
2297 | Apart from keeping your process non-blocking (which is a useful |
1439 | effect on its own sometimes), idle watchers are a good place to do |
2298 | effect on its own sometimes), idle watchers are a good place to do |
1440 | \&\*(L"pseudo\-background processing\*(R", or delay processing stuff to after the |
2299 | \&\*(L"pseudo-background processing\*(R", or delay processing stuff to after the |
1441 | event loop has handled all outstanding events. |
2300 | event loop has handled all outstanding events. |
|
|
2301 | .PP |
|
|
2302 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
2303 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1442 | .IP "ev_idle_init (ev_signal *, callback)" 4 |
2304 | .IP "ev_idle_init (ev_signal *, callback)" 4 |
1443 | .IX Item "ev_idle_init (ev_signal *, callback)" |
2305 | .IX Item "ev_idle_init (ev_signal *, callback)" |
1444 | Initialises and configures the idle watcher \- it has no parameters of any |
2306 | Initialises and configures the idle watcher \- it has no parameters of any |
1445 | kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, |
2307 | kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, |
1446 | believe me. |
2308 | believe me. |
1447 | .PP |
2309 | .PP |
|
|
2310 | \fIExamples\fR |
|
|
2311 | .IX Subsection "Examples" |
|
|
2312 | .PP |
1448 | Example: dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR, start it, and in the |
2313 | Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the |
1449 | callback, free it. Alos, use no error checking, as usual. |
2314 | callback, free it. Also, use no error checking, as usual. |
1450 | .PP |
2315 | .PP |
1451 | .Vb 7 |
2316 | .Vb 7 |
1452 | \& static void |
2317 | \& static void |
1453 | \& idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
2318 | \& idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
1454 | \& { |
2319 | \& { |
1455 | \& free (w); |
2320 | \& free (w); |
1456 | \& // now do something you wanted to do when the program has |
2321 | \& // now do something you wanted to do when the program has |
1457 | \& // no longer asnything immediate to do. |
2322 | \& // no longer anything immediate to do. |
1458 | \& } |
2323 | \& } |
1459 | .Ve |
2324 | \& |
1460 | .PP |
|
|
1461 | .Vb 3 |
|
|
1462 | \& struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
2325 | \& ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
1463 | \& ev_idle_init (idle_watcher, idle_cb); |
2326 | \& ev_idle_init (idle_watcher, idle_cb); |
1464 | \& ev_idle_start (loop, idle_cb); |
2327 | \& ev_idle_start (loop, idle_cb); |
1465 | .Ve |
2328 | .Ve |
1466 | .ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop!" |
2329 | .ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop!" |
1467 | .el .Sh "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!" |
2330 | .el .Sh "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!" |
1468 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
2331 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
1469 | Prepare and check watchers are usually (but not always) used in tandem: |
2332 | Prepare and check watchers are usually (but not always) used in pairs: |
1470 | prepare watchers get invoked before the process blocks and check watchers |
2333 | prepare watchers get invoked before the process blocks and check watchers |
1471 | afterwards. |
2334 | afterwards. |
1472 | .PP |
2335 | .PP |
1473 | You \fImust not\fR call \f(CW\*(C`ev_loop\*(C'\fR or similar functions that enter |
2336 | You \fImust not\fR call \f(CW\*(C`ev_loop\*(C'\fR or similar functions that enter |
1474 | the current event loop from either \f(CW\*(C`ev_prepare\*(C'\fR or \f(CW\*(C`ev_check\*(C'\fR |
2337 | the current event loop from either \f(CW\*(C`ev_prepare\*(C'\fR or \f(CW\*(C`ev_check\*(C'\fR |
… | |
… | |
1477 | those watchers, i.e. the sequence will always be \f(CW\*(C`ev_prepare\*(C'\fR, blocking, |
2340 | those watchers, i.e. the sequence will always be \f(CW\*(C`ev_prepare\*(C'\fR, blocking, |
1478 | \&\f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each kind they will always be |
2341 | \&\f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each kind they will always be |
1479 | called in pairs bracketing the blocking call. |
2342 | called in pairs bracketing the blocking call. |
1480 | .PP |
2343 | .PP |
1481 | Their main purpose is to integrate other event mechanisms into libev and |
2344 | Their main purpose is to integrate other event mechanisms into libev and |
1482 | their use is somewhat advanced. This could be used, for example, to track |
2345 | their use is somewhat advanced. They could be used, for example, to track |
1483 | variable changes, implement your own watchers, integrate net-snmp or a |
2346 | variable changes, implement your own watchers, integrate net-snmp or a |
1484 | coroutine library and lots more. They are also occasionally useful if |
2347 | coroutine library and lots more. They are also occasionally useful if |
1485 | you cache some data and want to flush it before blocking (for example, |
2348 | you cache some data and want to flush it before blocking (for example, |
1486 | in X programs you might want to do an \f(CW\*(C`XFlush ()\*(C'\fR in an \f(CW\*(C`ev_prepare\*(C'\fR |
2349 | in X programs you might want to do an \f(CW\*(C`XFlush ()\*(C'\fR in an \f(CW\*(C`ev_prepare\*(C'\fR |
1487 | watcher). |
2350 | watcher). |
1488 | .PP |
2351 | .PP |
1489 | This is done by examining in each prepare call which file descriptors need |
2352 | This is done by examining in each prepare call which file descriptors |
1490 | to be watched by the other library, registering \f(CW\*(C`ev_io\*(C'\fR watchers for |
2353 | need to be watched by the other library, registering \f(CW\*(C`ev_io\*(C'\fR watchers |
1491 | them and starting an \f(CW\*(C`ev_timer\*(C'\fR watcher for any timeouts (many libraries |
2354 | for them and starting an \f(CW\*(C`ev_timer\*(C'\fR watcher for any timeouts (many |
1492 | provide just this functionality). Then, in the check watcher you check for |
2355 | libraries provide exactly this functionality). Then, in the check watcher, |
1493 | any events that occured (by checking the pending status of all watchers |
2356 | you check for any events that occurred (by checking the pending status |
1494 | and stopping them) and call back into the library. The I/O and timer |
2357 | of all watchers and stopping them) and call back into the library. The |
1495 | callbacks will never actually be called (but must be valid nevertheless, |
2358 | I/O and timer callbacks will never actually be called (but must be valid |
1496 | because you never know, you know?). |
2359 | nevertheless, because you never know, you know?). |
1497 | .PP |
2360 | .PP |
1498 | As another example, the Perl Coro module uses these hooks to integrate |
2361 | As another example, the Perl Coro module uses these hooks to integrate |
1499 | coroutines into libev programs, by yielding to other active coroutines |
2362 | coroutines into libev programs, by yielding to other active coroutines |
1500 | during each prepare and only letting the process block if no coroutines |
2363 | during each prepare and only letting the process block if no coroutines |
1501 | are ready to run (it's actually more complicated: it only runs coroutines |
2364 | are ready to run (it's actually more complicated: it only runs coroutines |
1502 | with priority higher than or equal to the event loop and one coroutine |
2365 | with priority higher than or equal to the event loop and one coroutine |
1503 | of lower priority, but only once, using idle watchers to keep the event |
2366 | of lower priority, but only once, using idle watchers to keep the event |
1504 | loop from blocking if lower-priority coroutines are active, thus mapping |
2367 | loop from blocking if lower-priority coroutines are active, thus mapping |
1505 | low-priority coroutines to idle/background tasks). |
2368 | low-priority coroutines to idle/background tasks). |
|
|
2369 | .PP |
|
|
2370 | It is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR) |
|
|
2371 | priority, to ensure that they are being run before any other watchers |
|
|
2372 | after the poll (this doesn't matter for \f(CW\*(C`ev_prepare\*(C'\fR watchers). |
|
|
2373 | .PP |
|
|
2374 | Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers, too) should not |
|
|
2375 | activate (\*(L"feed\*(R") events into libev. While libev fully supports this, they |
|
|
2376 | might get executed before other \f(CW\*(C`ev_check\*(C'\fR watchers did their job. As |
|
|
2377 | \&\f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other (non-libev) event |
|
|
2378 | loops those other event loops might be in an unusable state until their |
|
|
2379 | \&\f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to coexist peacefully with |
|
|
2380 | others). |
|
|
2381 | .PP |
|
|
2382 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
2383 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1506 | .IP "ev_prepare_init (ev_prepare *, callback)" 4 |
2384 | .IP "ev_prepare_init (ev_prepare *, callback)" 4 |
1507 | .IX Item "ev_prepare_init (ev_prepare *, callback)" |
2385 | .IX Item "ev_prepare_init (ev_prepare *, callback)" |
1508 | .PD 0 |
2386 | .PD 0 |
1509 | .IP "ev_check_init (ev_check *, callback)" 4 |
2387 | .IP "ev_check_init (ev_check *, callback)" 4 |
1510 | .IX Item "ev_check_init (ev_check *, callback)" |
2388 | .IX Item "ev_check_init (ev_check *, callback)" |
1511 | .PD |
2389 | .PD |
1512 | Initialises and configures the prepare or check watcher \- they have no |
2390 | Initialises and configures the prepare or check watcher \- they have no |
1513 | parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR |
2391 | parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR |
1514 | macros, but using them is utterly, utterly and completely pointless. |
2392 | macros, but using them is utterly, utterly, utterly and completely |
|
|
2393 | pointless. |
1515 | .PP |
2394 | .PP |
1516 | Example: To include a library such as adns, you would add \s-1IO\s0 watchers |
2395 | \fIExamples\fR |
1517 | and a timeout watcher in a prepare handler, as required by libadns, and |
2396 | .IX Subsection "Examples" |
|
|
2397 | .PP |
|
|
2398 | There are a number of principal ways to embed other event loops or modules |
|
|
2399 | into libev. Here are some ideas on how to include libadns into libev |
|
|
2400 | (there is a Perl module named \f(CW\*(C`EV::ADNS\*(C'\fR that does this, which you could |
|
|
2401 | use as a working example. Another Perl module named \f(CW\*(C`EV::Glib\*(C'\fR embeds a |
|
|
2402 | Glib main context into libev, and finally, \f(CW\*(C`Glib::EV\*(C'\fR embeds \s-1EV\s0 into the |
|
|
2403 | Glib event loop). |
|
|
2404 | .PP |
|
|
2405 | Method 1: Add \s-1IO\s0 watchers and a timeout watcher in a prepare handler, |
1518 | in a check watcher, destroy them and call into libadns. What follows is |
2406 | and in a check watcher, destroy them and call into libadns. What follows |
1519 | pseudo-code only of course: |
2407 | is pseudo-code only of course. This requires you to either use a low |
|
|
2408 | priority for the check watcher or use \f(CW\*(C`ev_clear_pending\*(C'\fR explicitly, as |
|
|
2409 | the callbacks for the IO/timeout watchers might not have been called yet. |
1520 | .PP |
2410 | .PP |
1521 | .Vb 2 |
2411 | .Vb 2 |
1522 | \& static ev_io iow [nfd]; |
2412 | \& static ev_io iow [nfd]; |
1523 | \& static ev_timer tw; |
2413 | \& static ev_timer tw; |
1524 | .Ve |
2414 | \& |
1525 | .PP |
|
|
1526 | .Vb 9 |
|
|
1527 | \& static void |
2415 | \& static void |
1528 | \& io_cb (ev_loop *loop, ev_io *w, int revents) |
2416 | \& io_cb (struct ev_loop *loop, ev_io *w, int revents) |
1529 | \& { |
2417 | \& { |
1530 | \& // set the relevant poll flags |
|
|
1531 | \& // could also call adns_processreadable etc. here |
|
|
1532 | \& struct pollfd *fd = (struct pollfd *)w->data; |
|
|
1533 | \& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1534 | \& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1535 | \& } |
2418 | \& } |
1536 | .Ve |
2419 | \& |
1537 | .PP |
|
|
1538 | .Vb 7 |
|
|
1539 | \& // create io watchers for each fd and a timer before blocking |
2420 | \& // create io watchers for each fd and a timer before blocking |
1540 | \& static void |
2421 | \& static void |
1541 | \& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
2422 | \& adns_prepare_cb (struct ev_loop *loop, ev_prepare *w, int revents) |
1542 | \& { |
2423 | \& { |
1543 | \& int timeout = 3600000;truct pollfd fds [nfd]; |
2424 | \& int timeout = 3600000; |
|
|
2425 | \& struct pollfd fds [nfd]; |
1544 | \& // actual code will need to loop here and realloc etc. |
2426 | \& // actual code will need to loop here and realloc etc. |
1545 | \& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
2427 | \& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1546 | .Ve |
2428 | \& |
1547 | .PP |
|
|
1548 | .Vb 3 |
|
|
1549 | \& /* the callback is illegal, but won't be called as we stop during check */ |
2429 | \& /* the callback is illegal, but won\*(Aqt be called as we stop during check */ |
1550 | \& ev_timer_init (&tw, 0, timeout * 1e-3); |
2430 | \& ev_timer_init (&tw, 0, timeout * 1e\-3); |
1551 | \& ev_timer_start (loop, &tw); |
2431 | \& ev_timer_start (loop, &tw); |
1552 | .Ve |
2432 | \& |
1553 | .PP |
|
|
1554 | .Vb 6 |
|
|
1555 | \& // create on ev_io per pollfd |
2433 | \& // create one ev_io per pollfd |
1556 | \& for (int i = 0; i < nfd; ++i) |
2434 | \& for (int i = 0; i < nfd; ++i) |
1557 | \& { |
2435 | \& { |
1558 | \& ev_io_init (iow + i, io_cb, fds [i].fd, |
2436 | \& ev_io_init (iow + i, io_cb, fds [i].fd, |
1559 | \& ((fds [i].events & POLLIN ? EV_READ : 0) |
2437 | \& ((fds [i].events & POLLIN ? EV_READ : 0) |
1560 | \& | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
2438 | \& | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
|
|
2439 | \& |
|
|
2440 | \& fds [i].revents = 0; |
|
|
2441 | \& ev_io_start (loop, iow + i); |
|
|
2442 | \& } |
|
|
2443 | \& } |
|
|
2444 | \& |
|
|
2445 | \& // stop all watchers after blocking |
|
|
2446 | \& static void |
|
|
2447 | \& adns_check_cb (struct ev_loop *loop, ev_check *w, int revents) |
|
|
2448 | \& { |
|
|
2449 | \& ev_timer_stop (loop, &tw); |
|
|
2450 | \& |
|
|
2451 | \& for (int i = 0; i < nfd; ++i) |
|
|
2452 | \& { |
|
|
2453 | \& // set the relevant poll flags |
|
|
2454 | \& // could also call adns_processreadable etc. here |
|
|
2455 | \& struct pollfd *fd = fds + i; |
|
|
2456 | \& int revents = ev_clear_pending (iow + i); |
|
|
2457 | \& if (revents & EV_READ ) fd\->revents |= fd\->events & POLLIN; |
|
|
2458 | \& if (revents & EV_WRITE) fd\->revents |= fd\->events & POLLOUT; |
|
|
2459 | \& |
|
|
2460 | \& // now stop the watcher |
|
|
2461 | \& ev_io_stop (loop, iow + i); |
|
|
2462 | \& } |
|
|
2463 | \& |
|
|
2464 | \& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
2465 | \& } |
1561 | .Ve |
2466 | .Ve |
|
|
2467 | .PP |
|
|
2468 | Method 2: This would be just like method 1, but you run \f(CW\*(C`adns_afterpoll\*(C'\fR |
|
|
2469 | in the prepare watcher and would dispose of the check watcher. |
|
|
2470 | .PP |
|
|
2471 | Method 3: If the module to be embedded supports explicit event |
|
|
2472 | notification (libadns does), you can also make use of the actual watcher |
|
|
2473 | callbacks, and only destroy/create the watchers in the prepare watcher. |
1562 | .PP |
2474 | .PP |
1563 | .Vb 5 |
2475 | .Vb 5 |
1564 | \& fds [i].revents = 0; |
|
|
1565 | \& iow [i].data = fds + i; |
|
|
1566 | \& ev_io_start (loop, iow + i); |
|
|
1567 | \& } |
|
|
1568 | \& } |
|
|
1569 | .Ve |
|
|
1570 | .PP |
|
|
1571 | .Vb 5 |
|
|
1572 | \& // stop all watchers after blocking |
|
|
1573 | \& static void |
2476 | \& static void |
1574 | \& adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
2477 | \& timer_cb (EV_P_ ev_timer *w, int revents) |
1575 | \& { |
2478 | \& { |
1576 | \& ev_timer_stop (loop, &tw); |
2479 | \& adns_state ads = (adns_state)w\->data; |
1577 | .Ve |
2480 | \& update_now (EV_A); |
1578 | .PP |
2481 | \& |
1579 | .Vb 2 |
2482 | \& adns_processtimeouts (ads, &tv_now); |
1580 | \& for (int i = 0; i < nfd; ++i) |
|
|
1581 | \& ev_io_stop (loop, iow + i); |
|
|
1582 | .Ve |
|
|
1583 | .PP |
|
|
1584 | .Vb 2 |
|
|
1585 | \& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
1586 | \& } |
2483 | \& } |
|
|
2484 | \& |
|
|
2485 | \& static void |
|
|
2486 | \& io_cb (EV_P_ ev_io *w, int revents) |
|
|
2487 | \& { |
|
|
2488 | \& adns_state ads = (adns_state)w\->data; |
|
|
2489 | \& update_now (EV_A); |
|
|
2490 | \& |
|
|
2491 | \& if (revents & EV_READ ) adns_processreadable (ads, w\->fd, &tv_now); |
|
|
2492 | \& if (revents & EV_WRITE) adns_processwriteable (ads, w\->fd, &tv_now); |
|
|
2493 | \& } |
|
|
2494 | \& |
|
|
2495 | \& // do not ever call adns_afterpoll |
|
|
2496 | .Ve |
|
|
2497 | .PP |
|
|
2498 | Method 4: Do not use a prepare or check watcher because the module you |
|
|
2499 | want to embed is not flexible enough to support it. Instead, you can |
|
|
2500 | override their poll function. The drawback with this solution is that the |
|
|
2501 | main loop is now no longer controllable by \s-1EV\s0. The \f(CW\*(C`Glib::EV\*(C'\fR module uses |
|
|
2502 | this approach, effectively embedding \s-1EV\s0 as a client into the horrible |
|
|
2503 | libglib event loop. |
|
|
2504 | .PP |
|
|
2505 | .Vb 4 |
|
|
2506 | \& static gint |
|
|
2507 | \& event_poll_func (GPollFD *fds, guint nfds, gint timeout) |
|
|
2508 | \& { |
|
|
2509 | \& int got_events = 0; |
|
|
2510 | \& |
|
|
2511 | \& for (n = 0; n < nfds; ++n) |
|
|
2512 | \& // create/start io watcher that sets the relevant bits in fds[n] and increment got_events |
|
|
2513 | \& |
|
|
2514 | \& if (timeout >= 0) |
|
|
2515 | \& // create/start timer |
|
|
2516 | \& |
|
|
2517 | \& // poll |
|
|
2518 | \& ev_loop (EV_A_ 0); |
|
|
2519 | \& |
|
|
2520 | \& // stop timer again |
|
|
2521 | \& if (timeout >= 0) |
|
|
2522 | \& ev_timer_stop (EV_A_ &to); |
|
|
2523 | \& |
|
|
2524 | \& // stop io watchers again \- their callbacks should have set |
|
|
2525 | \& for (n = 0; n < nfds; ++n) |
|
|
2526 | \& ev_io_stop (EV_A_ iow [n]); |
|
|
2527 | \& |
|
|
2528 | \& return got_events; |
|
|
2529 | \& } |
1587 | .Ve |
2530 | .Ve |
1588 | .ie n .Sh """ev_embed"" \- when one backend isn't enough..." |
2531 | .ie n .Sh """ev_embed"" \- when one backend isn't enough..." |
1589 | .el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..." |
2532 | .el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..." |
1590 | .IX Subsection "ev_embed - when one backend isn't enough..." |
2533 | .IX Subsection "ev_embed - when one backend isn't enough..." |
1591 | This is a rather advanced watcher type that lets you embed one event loop |
2534 | This is a rather advanced watcher type that lets you embed one event loop |
… | |
… | |
1597 | prioritise I/O. |
2540 | prioritise I/O. |
1598 | .PP |
2541 | .PP |
1599 | As an example for a bug workaround, the kqueue backend might only support |
2542 | As an example for a bug workaround, the kqueue backend might only support |
1600 | sockets on some platform, so it is unusable as generic backend, but you |
2543 | sockets on some platform, so it is unusable as generic backend, but you |
1601 | still want to make use of it because you have many sockets and it scales |
2544 | still want to make use of it because you have many sockets and it scales |
1602 | so nicely. In this case, you would create a kqueue-based loop and embed it |
2545 | so nicely. In this case, you would create a kqueue-based loop and embed |
1603 | into your default loop (which might use e.g. poll). Overall operation will |
2546 | it into your default loop (which might use e.g. poll). Overall operation |
1604 | be a bit slower because first libev has to poll and then call kevent, but |
2547 | will be a bit slower because first libev has to call \f(CW\*(C`poll\*(C'\fR and then |
1605 | at least you can use both at what they are best. |
2548 | \&\f(CW\*(C`kevent\*(C'\fR, but at least you can use both mechanisms for what they are |
|
|
2549 | best: \f(CW\*(C`kqueue\*(C'\fR for scalable sockets and \f(CW\*(C`poll\*(C'\fR if you want it to work :) |
1606 | .PP |
2550 | .PP |
1607 | As for prioritising I/O: rarely you have the case where some fds have |
2551 | As for prioritising I/O: under rare circumstances you have the case where |
1608 | to be watched and handled very quickly (with low latency), and even |
2552 | some fds have to be watched and handled very quickly (with low latency), |
1609 | priorities and idle watchers might have too much overhead. In this case |
2553 | and even priorities and idle watchers might have too much overhead. In |
1610 | you would put all the high priority stuff in one loop and all the rest in |
2554 | this case you would put all the high priority stuff in one loop and all |
1611 | a second one, and embed the second one in the first. |
2555 | the rest in a second one, and embed the second one in the first. |
1612 | .PP |
2556 | .PP |
1613 | As long as the watcher is active, the callback will be invoked every time |
2557 | As long as the watcher is active, the callback will be invoked every time |
1614 | there might be events pending in the embedded loop. The callback must then |
2558 | there might be events pending in the embedded loop. The callback must then |
1615 | call \f(CW\*(C`ev_embed_sweep (mainloop, watcher)\*(C'\fR to make a single sweep and invoke |
2559 | call \f(CW\*(C`ev_embed_sweep (mainloop, watcher)\*(C'\fR to make a single sweep and invoke |
1616 | their callbacks (you could also start an idle watcher to give the embedded |
2560 | their callbacks (you could also start an idle watcher to give the embedded |
… | |
… | |
1624 | interested in that. |
2568 | interested in that. |
1625 | .PP |
2569 | .PP |
1626 | Also, there have not currently been made special provisions for forking: |
2570 | Also, there have not currently been made special provisions for forking: |
1627 | when you fork, you not only have to call \f(CW\*(C`ev_loop_fork\*(C'\fR on both loops, |
2571 | when you fork, you not only have to call \f(CW\*(C`ev_loop_fork\*(C'\fR on both loops, |
1628 | but you will also have to stop and restart any \f(CW\*(C`ev_embed\*(C'\fR watchers |
2572 | but you will also have to stop and restart any \f(CW\*(C`ev_embed\*(C'\fR watchers |
1629 | yourself. |
2573 | yourself \- but you can use a fork watcher to handle this automatically, |
|
|
2574 | and future versions of libev might do just that. |
1630 | .PP |
2575 | .PP |
1631 | Unfortunately, not all backends are embeddable, only the ones returned by |
2576 | Unfortunately, not all backends are embeddable: only the ones returned by |
1632 | \&\f(CW\*(C`ev_embeddable_backends\*(C'\fR are, which, unfortunately, does not include any |
2577 | \&\f(CW\*(C`ev_embeddable_backends\*(C'\fR are, which, unfortunately, does not include any |
1633 | portable one. |
2578 | portable one. |
1634 | .PP |
2579 | .PP |
1635 | So when you want to use this feature you will always have to be prepared |
2580 | So when you want to use this feature you will always have to be prepared |
1636 | that you cannot get an embeddable loop. The recommended way to get around |
2581 | that you cannot get an embeddable loop. The recommended way to get around |
1637 | this is to have a separate variables for your embeddable loop, try to |
2582 | this is to have a separate variables for your embeddable loop, try to |
1638 | create it, and if that fails, use the normal loop for everything: |
2583 | create it, and if that fails, use the normal loop for everything. |
1639 | .PP |
2584 | .PP |
1640 | .Vb 3 |
2585 | \fI\f(CI\*(C`ev_embed\*(C'\fI and fork\fR |
1641 | \& struct ev_loop *loop_hi = ev_default_init (0); |
2586 | .IX Subsection "ev_embed and fork" |
1642 | \& struct ev_loop *loop_lo = 0; |
|
|
1643 | \& struct ev_embed embed; |
|
|
1644 | .Ve |
|
|
1645 | .PP |
2587 | .PP |
1646 | .Vb 5 |
2588 | While the \f(CW\*(C`ev_embed\*(C'\fR watcher is running, forks in the embedding loop will |
1647 | \& // see if there is a chance of getting one that works |
2589 | automatically be applied to the embedded loop as well, so no special |
1648 | \& // (remember that a flags value of 0 means autodetection) |
2590 | fork handling is required in that case. When the watcher is not running, |
1649 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
2591 | however, it is still the task of the libev user to call \f(CW\*(C`ev_loop_fork ()\*(C'\fR |
1650 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
2592 | as applicable. |
1651 | \& : 0; |
|
|
1652 | .Ve |
|
|
1653 | .PP |
2593 | .PP |
1654 | .Vb 8 |
2594 | \fIWatcher-Specific Functions and Data Members\fR |
1655 | \& // if we got one, then embed it, otherwise default to loop_hi |
2595 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1656 | \& if (loop_lo) |
|
|
1657 | \& { |
|
|
1658 | \& ev_embed_init (&embed, 0, loop_lo); |
|
|
1659 | \& ev_embed_start (loop_hi, &embed); |
|
|
1660 | \& } |
|
|
1661 | \& else |
|
|
1662 | \& loop_lo = loop_hi; |
|
|
1663 | .Ve |
|
|
1664 | .IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
2596 | .IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
1665 | .IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" |
2597 | .IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" |
1666 | .PD 0 |
2598 | .PD 0 |
1667 | .IP "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
2599 | .IP "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
1668 | .IX Item "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" |
2600 | .IX Item "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" |
1669 | .PD |
2601 | .PD |
1670 | Configures the watcher to embed the given loop, which must be |
2602 | Configures the watcher to embed the given loop, which must be |
1671 | embeddable. If the callback is \f(CW0\fR, then \f(CW\*(C`ev_embed_sweep\*(C'\fR will be |
2603 | embeddable. If the callback is \f(CW0\fR, then \f(CW\*(C`ev_embed_sweep\*(C'\fR will be |
1672 | invoked automatically, otherwise it is the responsibility of the callback |
2604 | invoked automatically, otherwise it is the responsibility of the callback |
1673 | to invoke it (it will continue to be called until the sweep has been done, |
2605 | to invoke it (it will continue to be called until the sweep has been done, |
1674 | if you do not want thta, you need to temporarily stop the embed watcher). |
2606 | if you do not want that, you need to temporarily stop the embed watcher). |
1675 | .IP "ev_embed_sweep (loop, ev_embed *)" 4 |
2607 | .IP "ev_embed_sweep (loop, ev_embed *)" 4 |
1676 | .IX Item "ev_embed_sweep (loop, ev_embed *)" |
2608 | .IX Item "ev_embed_sweep (loop, ev_embed *)" |
1677 | Make a single, non-blocking sweep over the embedded loop. This works |
2609 | Make a single, non-blocking sweep over the embedded loop. This works |
1678 | similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most |
2610 | similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most |
1679 | apropriate way for embedded loops. |
2611 | appropriate way for embedded loops. |
1680 | .IP "struct ev_loop *loop [read\-only]" 4 |
2612 | .IP "struct ev_loop *other [read\-only]" 4 |
1681 | .IX Item "struct ev_loop *loop [read-only]" |
2613 | .IX Item "struct ev_loop *other [read-only]" |
1682 | The embedded event loop. |
2614 | The embedded event loop. |
|
|
2615 | .PP |
|
|
2616 | \fIExamples\fR |
|
|
2617 | .IX Subsection "Examples" |
|
|
2618 | .PP |
|
|
2619 | Example: Try to get an embeddable event loop and embed it into the default |
|
|
2620 | event loop. If that is not possible, use the default loop. The default |
|
|
2621 | loop is stored in \f(CW\*(C`loop_hi\*(C'\fR, while the embeddable loop is stored in |
|
|
2622 | \&\f(CW\*(C`loop_lo\*(C'\fR (which is \f(CW\*(C`loop_hi\*(C'\fR in the case no embeddable loop can be |
|
|
2623 | used). |
|
|
2624 | .PP |
|
|
2625 | .Vb 3 |
|
|
2626 | \& struct ev_loop *loop_hi = ev_default_init (0); |
|
|
2627 | \& struct ev_loop *loop_lo = 0; |
|
|
2628 | \& ev_embed embed; |
|
|
2629 | \& |
|
|
2630 | \& // see if there is a chance of getting one that works |
|
|
2631 | \& // (remember that a flags value of 0 means autodetection) |
|
|
2632 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
|
|
2633 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
|
|
2634 | \& : 0; |
|
|
2635 | \& |
|
|
2636 | \& // if we got one, then embed it, otherwise default to loop_hi |
|
|
2637 | \& if (loop_lo) |
|
|
2638 | \& { |
|
|
2639 | \& ev_embed_init (&embed, 0, loop_lo); |
|
|
2640 | \& ev_embed_start (loop_hi, &embed); |
|
|
2641 | \& } |
|
|
2642 | \& else |
|
|
2643 | \& loop_lo = loop_hi; |
|
|
2644 | .Ve |
|
|
2645 | .PP |
|
|
2646 | Example: Check if kqueue is available but not recommended and create |
|
|
2647 | a kqueue backend for use with sockets (which usually work with any |
|
|
2648 | kqueue implementation). Store the kqueue/socket\-only event loop in |
|
|
2649 | \&\f(CW\*(C`loop_socket\*(C'\fR. (One might optionally use \f(CW\*(C`EVFLAG_NOENV\*(C'\fR, too). |
|
|
2650 | .PP |
|
|
2651 | .Vb 3 |
|
|
2652 | \& struct ev_loop *loop = ev_default_init (0); |
|
|
2653 | \& struct ev_loop *loop_socket = 0; |
|
|
2654 | \& ev_embed embed; |
|
|
2655 | \& |
|
|
2656 | \& if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
|
|
2657 | \& if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
|
|
2658 | \& { |
|
|
2659 | \& ev_embed_init (&embed, 0, loop_socket); |
|
|
2660 | \& ev_embed_start (loop, &embed); |
|
|
2661 | \& } |
|
|
2662 | \& |
|
|
2663 | \& if (!loop_socket) |
|
|
2664 | \& loop_socket = loop; |
|
|
2665 | \& |
|
|
2666 | \& // now use loop_socket for all sockets, and loop for everything else |
|
|
2667 | .Ve |
1683 | .ie n .Sh """ev_fork"" \- the audacity to resume the event loop after a fork" |
2668 | .ie n .Sh """ev_fork"" \- the audacity to resume the event loop after a fork" |
1684 | .el .Sh "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
2669 | .el .Sh "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
1685 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
2670 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
1686 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
2671 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
1687 | whoever is a good citizen cared to tell libev about it by calling |
2672 | whoever is a good citizen cared to tell libev about it by calling |
1688 | \&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the |
2673 | \&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the |
1689 | event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, |
2674 | event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, |
1690 | and only in the child after the fork. If whoever good citizen calling |
2675 | and only in the child after the fork. If whoever good citizen calling |
1691 | \&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork |
2676 | \&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork |
1692 | handlers will be invoked, too, of course. |
2677 | handlers will be invoked, too, of course. |
|
|
2678 | .PP |
|
|
2679 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
2680 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1693 | .IP "ev_fork_init (ev_signal *, callback)" 4 |
2681 | .IP "ev_fork_init (ev_signal *, callback)" 4 |
1694 | .IX Item "ev_fork_init (ev_signal *, callback)" |
2682 | .IX Item "ev_fork_init (ev_signal *, callback)" |
1695 | Initialises and configures the fork watcher \- it has no parameters of any |
2683 | Initialises and configures the fork watcher \- it has no parameters of any |
1696 | kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless, |
2684 | kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless, |
1697 | believe me. |
2685 | believe me. |
|
|
2686 | .ie n .Sh """ev_async"" \- how to wake up another event loop" |
|
|
2687 | .el .Sh "\f(CWev_async\fP \- how to wake up another event loop" |
|
|
2688 | .IX Subsection "ev_async - how to wake up another event loop" |
|
|
2689 | In general, you cannot use an \f(CW\*(C`ev_loop\*(C'\fR from multiple threads or other |
|
|
2690 | asynchronous sources such as signal handlers (as opposed to multiple event |
|
|
2691 | loops \- those are of course safe to use in different threads). |
|
|
2692 | .PP |
|
|
2693 | Sometimes, however, you need to wake up another event loop you do not |
|
|
2694 | control, for example because it belongs to another thread. This is what |
|
|
2695 | \&\f(CW\*(C`ev_async\*(C'\fR watchers do: as long as the \f(CW\*(C`ev_async\*(C'\fR watcher is active, you |
|
|
2696 | can signal it by calling \f(CW\*(C`ev_async_send\*(C'\fR, which is thread\- and signal |
|
|
2697 | safe. |
|
|
2698 | .PP |
|
|
2699 | This functionality is very similar to \f(CW\*(C`ev_signal\*(C'\fR watchers, as signals, |
|
|
2700 | too, are asynchronous in nature, and signals, too, will be compressed |
|
|
2701 | (i.e. the number of callback invocations may be less than the number of |
|
|
2702 | \&\f(CW\*(C`ev_async_sent\*(C'\fR calls). |
|
|
2703 | .PP |
|
|
2704 | Unlike \f(CW\*(C`ev_signal\*(C'\fR watchers, \f(CW\*(C`ev_async\*(C'\fR works with any event loop, not |
|
|
2705 | just the default loop. |
|
|
2706 | .PP |
|
|
2707 | \fIQueueing\fR |
|
|
2708 | .IX Subsection "Queueing" |
|
|
2709 | .PP |
|
|
2710 | \&\f(CW\*(C`ev_async\*(C'\fR does not support queueing of data in any way. The reason |
|
|
2711 | is that the author does not know of a simple (or any) algorithm for a |
|
|
2712 | multiple-writer-single-reader queue that works in all cases and doesn't |
|
|
2713 | need elaborate support such as pthreads. |
|
|
2714 | .PP |
|
|
2715 | That means that if you want to queue data, you have to provide your own |
|
|
2716 | queue. But at least I can tell you how to implement locking around your |
|
|
2717 | queue: |
|
|
2718 | .IP "queueing from a signal handler context" 4 |
|
|
2719 | .IX Item "queueing from a signal handler context" |
|
|
2720 | To implement race-free queueing, you simply add to the queue in the signal |
|
|
2721 | handler but you block the signal handler in the watcher callback. Here is |
|
|
2722 | an example that does that for some fictitious \s-1SIGUSR1\s0 handler: |
|
|
2723 | .Sp |
|
|
2724 | .Vb 1 |
|
|
2725 | \& static ev_async mysig; |
|
|
2726 | \& |
|
|
2727 | \& static void |
|
|
2728 | \& sigusr1_handler (void) |
|
|
2729 | \& { |
|
|
2730 | \& sometype data; |
|
|
2731 | \& |
|
|
2732 | \& // no locking etc. |
|
|
2733 | \& queue_put (data); |
|
|
2734 | \& ev_async_send (EV_DEFAULT_ &mysig); |
|
|
2735 | \& } |
|
|
2736 | \& |
|
|
2737 | \& static void |
|
|
2738 | \& mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
2739 | \& { |
|
|
2740 | \& sometype data; |
|
|
2741 | \& sigset_t block, prev; |
|
|
2742 | \& |
|
|
2743 | \& sigemptyset (&block); |
|
|
2744 | \& sigaddset (&block, SIGUSR1); |
|
|
2745 | \& sigprocmask (SIG_BLOCK, &block, &prev); |
|
|
2746 | \& |
|
|
2747 | \& while (queue_get (&data)) |
|
|
2748 | \& process (data); |
|
|
2749 | \& |
|
|
2750 | \& if (sigismember (&prev, SIGUSR1) |
|
|
2751 | \& sigprocmask (SIG_UNBLOCK, &block, 0); |
|
|
2752 | \& } |
|
|
2753 | .Ve |
|
|
2754 | .Sp |
|
|
2755 | (Note: pthreads in theory requires you to use \f(CW\*(C`pthread_setmask\*(C'\fR |
|
|
2756 | instead of \f(CW\*(C`sigprocmask\*(C'\fR when you use threads, but libev doesn't do it |
|
|
2757 | either...). |
|
|
2758 | .IP "queueing from a thread context" 4 |
|
|
2759 | .IX Item "queueing from a thread context" |
|
|
2760 | The strategy for threads is different, as you cannot (easily) block |
|
|
2761 | threads but you can easily preempt them, so to queue safely you need to |
|
|
2762 | employ a traditional mutex lock, such as in this pthread example: |
|
|
2763 | .Sp |
|
|
2764 | .Vb 2 |
|
|
2765 | \& static ev_async mysig; |
|
|
2766 | \& static pthread_mutex_t mymutex = PTHREAD_MUTEX_INITIALIZER; |
|
|
2767 | \& |
|
|
2768 | \& static void |
|
|
2769 | \& otherthread (void) |
|
|
2770 | \& { |
|
|
2771 | \& // only need to lock the actual queueing operation |
|
|
2772 | \& pthread_mutex_lock (&mymutex); |
|
|
2773 | \& queue_put (data); |
|
|
2774 | \& pthread_mutex_unlock (&mymutex); |
|
|
2775 | \& |
|
|
2776 | \& ev_async_send (EV_DEFAULT_ &mysig); |
|
|
2777 | \& } |
|
|
2778 | \& |
|
|
2779 | \& static void |
|
|
2780 | \& mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
2781 | \& { |
|
|
2782 | \& pthread_mutex_lock (&mymutex); |
|
|
2783 | \& |
|
|
2784 | \& while (queue_get (&data)) |
|
|
2785 | \& process (data); |
|
|
2786 | \& |
|
|
2787 | \& pthread_mutex_unlock (&mymutex); |
|
|
2788 | \& } |
|
|
2789 | .Ve |
|
|
2790 | .PP |
|
|
2791 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
2792 | .IX Subsection "Watcher-Specific Functions and Data Members" |
|
|
2793 | .IP "ev_async_init (ev_async *, callback)" 4 |
|
|
2794 | .IX Item "ev_async_init (ev_async *, callback)" |
|
|
2795 | Initialises and configures the async watcher \- it has no parameters of any |
|
|
2796 | kind. There is a \f(CW\*(C`ev_async_set\*(C'\fR macro, but using it is utterly pointless, |
|
|
2797 | trust me. |
|
|
2798 | .IP "ev_async_send (loop, ev_async *)" 4 |
|
|
2799 | .IX Item "ev_async_send (loop, ev_async *)" |
|
|
2800 | Sends/signals/activates the given \f(CW\*(C`ev_async\*(C'\fR watcher, that is, feeds |
|
|
2801 | an \f(CW\*(C`EV_ASYNC\*(C'\fR event on the watcher into the event loop. Unlike |
|
|
2802 | \&\f(CW\*(C`ev_feed_event\*(C'\fR, this call is safe to do from other threads, signal or |
|
|
2803 | similar contexts (see the discussion of \f(CW\*(C`EV_ATOMIC_T\*(C'\fR in the embedding |
|
|
2804 | section below on what exactly this means). |
|
|
2805 | .Sp |
|
|
2806 | This call incurs the overhead of a system call only once per loop iteration, |
|
|
2807 | so while the overhead might be noticeable, it doesn't apply to repeated |
|
|
2808 | calls to \f(CW\*(C`ev_async_send\*(C'\fR. |
|
|
2809 | .IP "bool = ev_async_pending (ev_async *)" 4 |
|
|
2810 | .IX Item "bool = ev_async_pending (ev_async *)" |
|
|
2811 | Returns a non-zero value when \f(CW\*(C`ev_async_send\*(C'\fR has been called on the |
|
|
2812 | watcher but the event has not yet been processed (or even noted) by the |
|
|
2813 | event loop. |
|
|
2814 | .Sp |
|
|
2815 | \&\f(CW\*(C`ev_async_send\*(C'\fR sets a flag in the watcher and wakes up the loop. When |
|
|
2816 | the loop iterates next and checks for the watcher to have become active, |
|
|
2817 | it will reset the flag again. \f(CW\*(C`ev_async_pending\*(C'\fR can be used to very |
|
|
2818 | quickly check whether invoking the loop might be a good idea. |
|
|
2819 | .Sp |
|
|
2820 | Not that this does \fInot\fR check whether the watcher itself is pending, only |
|
|
2821 | whether it has been requested to make this watcher pending. |
1698 | .SH "OTHER FUNCTIONS" |
2822 | .SH "OTHER FUNCTIONS" |
1699 | .IX Header "OTHER FUNCTIONS" |
2823 | .IX Header "OTHER FUNCTIONS" |
1700 | There are some other functions of possible interest. Described. Here. Now. |
2824 | There are some other functions of possible interest. Described. Here. Now. |
1701 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 |
2825 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 |
1702 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" |
2826 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" |
1703 | This function combines a simple timer and an I/O watcher, calls your |
2827 | This function combines a simple timer and an I/O watcher, calls your |
1704 | callback on whichever event happens first and automatically stop both |
2828 | callback on whichever event happens first and automatically stops both |
1705 | watchers. This is useful if you want to wait for a single event on an fd |
2829 | watchers. This is useful if you want to wait for a single event on an fd |
1706 | or timeout without having to allocate/configure/start/stop/free one or |
2830 | or timeout without having to allocate/configure/start/stop/free one or |
1707 | more watchers yourself. |
2831 | more watchers yourself. |
1708 | .Sp |
2832 | .Sp |
1709 | If \f(CW\*(C`fd\*(C'\fR is less than 0, then no I/O watcher will be started and events |
2833 | If \f(CW\*(C`fd\*(C'\fR is less than 0, then no I/O watcher will be started and the |
1710 | is being ignored. Otherwise, an \f(CW\*(C`ev_io\*(C'\fR watcher for the given \f(CW\*(C`fd\*(C'\fR and |
2834 | \&\f(CW\*(C`events\*(C'\fR argument is being ignored. Otherwise, an \f(CW\*(C`ev_io\*(C'\fR watcher for |
1711 | \&\f(CW\*(C`events\*(C'\fR set will be craeted and started. |
2835 | the given \f(CW\*(C`fd\*(C'\fR and \f(CW\*(C`events\*(C'\fR set will be created and started. |
1712 | .Sp |
2836 | .Sp |
1713 | If \f(CW\*(C`timeout\*(C'\fR is less than 0, then no timeout watcher will be |
2837 | If \f(CW\*(C`timeout\*(C'\fR is less than 0, then no timeout watcher will be |
1714 | started. Otherwise an \f(CW\*(C`ev_timer\*(C'\fR watcher with after = \f(CW\*(C`timeout\*(C'\fR (and |
2838 | started. Otherwise an \f(CW\*(C`ev_timer\*(C'\fR watcher with after = \f(CW\*(C`timeout\*(C'\fR (and |
1715 | repeat = 0) will be started. While \f(CW0\fR is a valid timeout, it is of |
2839 | repeat = 0) will be started. \f(CW0\fR is a valid timeout. |
1716 | dubious value. |
|
|
1717 | .Sp |
2840 | .Sp |
1718 | The callback has the type \f(CW\*(C`void (*cb)(int revents, void *arg)\*(C'\fR and gets |
2841 | The callback has the type \f(CW\*(C`void (*cb)(int revents, void *arg)\*(C'\fR and gets |
1719 | passed an \f(CW\*(C`revents\*(C'\fR set like normal event callbacks (a combination of |
2842 | passed an \f(CW\*(C`revents\*(C'\fR set like normal event callbacks (a combination of |
1720 | \&\f(CW\*(C`EV_ERROR\*(C'\fR, \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or \f(CW\*(C`EV_TIMEOUT\*(C'\fR) and the \f(CW\*(C`arg\*(C'\fR |
2843 | \&\f(CW\*(C`EV_ERROR\*(C'\fR, \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or \f(CW\*(C`EV_TIMEOUT\*(C'\fR) and the \f(CW\*(C`arg\*(C'\fR |
1721 | value passed to \f(CW\*(C`ev_once\*(C'\fR: |
2844 | value passed to \f(CW\*(C`ev_once\*(C'\fR. Note that it is possible to receive \fIboth\fR |
|
|
2845 | a timeout and an io event at the same time \- you probably should give io |
|
|
2846 | events precedence. |
|
|
2847 | .Sp |
|
|
2848 | Example: wait up to ten seconds for data to appear on \s-1STDIN_FILENO\s0. |
1722 | .Sp |
2849 | .Sp |
1723 | .Vb 7 |
2850 | .Vb 7 |
1724 | \& static void stdin_ready (int revents, void *arg) |
2851 | \& static void stdin_ready (int revents, void *arg) |
1725 | \& { |
2852 | \& { |
1726 | \& if (revents & EV_TIMEOUT) |
|
|
1727 | \& /* doh, nothing entered */; |
|
|
1728 | \& else if (revents & EV_READ) |
2853 | \& if (revents & EV_READ) |
1729 | \& /* stdin might have data for us, joy! */; |
2854 | \& /* stdin might have data for us, joy! */; |
|
|
2855 | \& else if (revents & EV_TIMEOUT) |
|
|
2856 | \& /* doh, nothing entered */; |
1730 | \& } |
2857 | \& } |
1731 | .Ve |
2858 | \& |
1732 | .Sp |
|
|
1733 | .Vb 1 |
|
|
1734 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
2859 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
1735 | .Ve |
2860 | .Ve |
1736 | .IP "ev_feed_event (ev_loop *, watcher *, int revents)" 4 |
2861 | .IP "ev_feed_event (struct ev_loop *, watcher *, int revents)" 4 |
1737 | .IX Item "ev_feed_event (ev_loop *, watcher *, int revents)" |
2862 | .IX Item "ev_feed_event (struct ev_loop *, watcher *, int revents)" |
1738 | Feeds the given event set into the event loop, as if the specified event |
2863 | Feeds the given event set into the event loop, as if the specified event |
1739 | had happened for the specified watcher (which must be a pointer to an |
2864 | had happened for the specified watcher (which must be a pointer to an |
1740 | initialised but not necessarily started event watcher). |
2865 | initialised but not necessarily started event watcher). |
1741 | .IP "ev_feed_fd_event (ev_loop *, int fd, int revents)" 4 |
2866 | .IP "ev_feed_fd_event (struct ev_loop *, int fd, int revents)" 4 |
1742 | .IX Item "ev_feed_fd_event (ev_loop *, int fd, int revents)" |
2867 | .IX Item "ev_feed_fd_event (struct ev_loop *, int fd, int revents)" |
1743 | Feed an event on the given fd, as if a file descriptor backend detected |
2868 | Feed an event on the given fd, as if a file descriptor backend detected |
1744 | the given events it. |
2869 | the given events it. |
1745 | .IP "ev_feed_signal_event (ev_loop *loop, int signum)" 4 |
2870 | .IP "ev_feed_signal_event (struct ev_loop *loop, int signum)" 4 |
1746 | .IX Item "ev_feed_signal_event (ev_loop *loop, int signum)" |
2871 | .IX Item "ev_feed_signal_event (struct ev_loop *loop, int signum)" |
1747 | Feed an event as if the given signal occured (\f(CW\*(C`loop\*(C'\fR must be the default |
2872 | Feed an event as if the given signal occurred (\f(CW\*(C`loop\*(C'\fR must be the default |
1748 | loop!). |
2873 | loop!). |
1749 | .SH "LIBEVENT EMULATION" |
2874 | .SH "LIBEVENT EMULATION" |
1750 | .IX Header "LIBEVENT EMULATION" |
2875 | .IX Header "LIBEVENT EMULATION" |
1751 | Libev offers a compatibility emulation layer for libevent. It cannot |
2876 | Libev offers a compatibility emulation layer for libevent. It cannot |
1752 | emulate the internals of libevent, so here are some usage hints: |
2877 | emulate the internals of libevent, so here are some usage hints: |
|
|
2878 | .IP "\(bu" 4 |
1753 | .IP "* Use it by including <event.h>, as usual." 4 |
2879 | Use it by including <event.h>, as usual. |
1754 | .IX Item "Use it by including <event.h>, as usual." |
2880 | .IP "\(bu" 4 |
1755 | .PD 0 |
2881 | The following members are fully supported: ev_base, ev_callback, |
1756 | .IP "* The following members are fully supported: ev_base, ev_callback, ev_arg, ev_fd, ev_res, ev_events." 4 |
2882 | ev_arg, ev_fd, ev_res, ev_events. |
1757 | .IX Item "The following members are fully supported: ev_base, ev_callback, ev_arg, ev_fd, ev_res, ev_events." |
2883 | .IP "\(bu" 4 |
1758 | .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 |
2884 | Avoid using ev_flags and the EVLIST_*\-macros, while it is |
1759 | .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)." |
2885 | maintained by libev, it does not work exactly the same way as in libevent (consider |
1760 | .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 |
2886 | it a private \s-1API\s0). |
1761 | .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." |
2887 | .IP "\(bu" 4 |
|
|
2888 | Priorities are not currently supported. Initialising priorities |
|
|
2889 | will fail and all watchers will have the same priority, even though there |
|
|
2890 | is an ev_pri field. |
|
|
2891 | .IP "\(bu" 4 |
|
|
2892 | In libevent, the last base created gets the signals, in libev, the |
|
|
2893 | first base created (== the default loop) gets the signals. |
|
|
2894 | .IP "\(bu" 4 |
1762 | .IP "* Other members are not supported." 4 |
2895 | Other members are not supported. |
1763 | .IX Item "Other members are not supported." |
2896 | .IP "\(bu" 4 |
1764 | .IP "* The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need to use the libev header file and library." 4 |
2897 | The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need |
1765 | .IX Item "The libev emulation is not ABI compatible to libevent, you need to use the libev header file and library." |
2898 | to use the libev header file and library. |
1766 | .PD |
|
|
1767 | .SH "\*(C+ SUPPORT" |
2899 | .SH "\*(C+ SUPPORT" |
1768 | .IX Header " SUPPORT" |
2900 | .IX Header " SUPPORT" |
1769 | Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow |
2901 | Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow |
1770 | you to use some convinience methods to start/stop watchers and also change |
2902 | you to use some convenience methods to start/stop watchers and also change |
1771 | the callback model to a model using method callbacks on objects. |
2903 | the callback model to a model using method callbacks on objects. |
1772 | .PP |
2904 | .PP |
1773 | To use it, |
2905 | To use it, |
1774 | .PP |
2906 | .PP |
1775 | .Vb 1 |
2907 | .Vb 1 |
1776 | \& #include <ev++.h> |
2908 | \& #include <ev++.h> |
1777 | .Ve |
2909 | .Ve |
1778 | .PP |
2910 | .PP |
1779 | (it is not installed by default). This automatically includes \fIev.h\fR |
2911 | This automatically includes \fIev.h\fR and puts all of its definitions (many |
1780 | and puts all of its definitions (many of them macros) into the global |
2912 | of them macros) into the global namespace. All \*(C+ specific things are |
1781 | namespace. All \*(C+ specific things are put into the \f(CW\*(C`ev\*(C'\fR namespace. |
2913 | put into the \f(CW\*(C`ev\*(C'\fR namespace. It should support all the same embedding |
|
|
2914 | options as \fIev.h\fR, most notably \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. |
1782 | .PP |
2915 | .PP |
1783 | It should support all the same embedding options as \fIev.h\fR, most notably |
2916 | Care has been taken to keep the overhead low. The only data member the \*(C+ |
1784 | \&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. |
2917 | classes add (compared to plain C\-style watchers) is the event loop pointer |
|
|
2918 | that the watcher is associated with (or no additional members at all if |
|
|
2919 | you disable \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR when embedding libev). |
|
|
2920 | .PP |
|
|
2921 | Currently, functions, and static and non-static member functions can be |
|
|
2922 | used as callbacks. Other types should be easy to add as long as they only |
|
|
2923 | need one additional pointer for context. If you need support for other |
|
|
2924 | types of functors please contact the author (preferably after implementing |
|
|
2925 | it). |
1785 | .PP |
2926 | .PP |
1786 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
2927 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
1787 | .ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4 |
2928 | .ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4 |
1788 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
2929 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
1789 | .IX Item "ev::READ, ev::WRITE etc." |
2930 | .IX Item "ev::READ, ev::WRITE etc." |
… | |
… | |
1801 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
2942 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
1802 | defines by many implementations. |
2943 | defines by many implementations. |
1803 | .Sp |
2944 | .Sp |
1804 | All of those classes have these methods: |
2945 | All of those classes have these methods: |
1805 | .RS 4 |
2946 | .RS 4 |
1806 | .IP "ev::TYPE::TYPE (object *, object::method *)" 4 |
2947 | .IP "ev::TYPE::TYPE ()" 4 |
1807 | .IX Item "ev::TYPE::TYPE (object *, object::method *)" |
2948 | .IX Item "ev::TYPE::TYPE ()" |
1808 | .PD 0 |
2949 | .PD 0 |
1809 | .IP "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" 4 |
2950 | .IP "ev::TYPE::TYPE (struct ev_loop *)" 4 |
1810 | .IX Item "ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)" |
2951 | .IX Item "ev::TYPE::TYPE (struct ev_loop *)" |
1811 | .IP "ev::TYPE::~TYPE" 4 |
2952 | .IP "ev::TYPE::~TYPE" 4 |
1812 | .IX Item "ev::TYPE::~TYPE" |
2953 | .IX Item "ev::TYPE::~TYPE" |
1813 | .PD |
2954 | .PD |
1814 | The constructor takes a pointer to an object and a method pointer to |
2955 | The constructor (optionally) takes an event loop to associate the watcher |
1815 | the event handler callback to call in this class. The constructor calls |
2956 | with. If it is omitted, it will use \f(CW\*(C`EV_DEFAULT\*(C'\fR. |
1816 | \&\f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the \f(CW\*(C`set\*(C'\fR method |
2957 | .Sp |
1817 | before starting it. If you do not specify a loop then the constructor |
2958 | The constructor calls \f(CW\*(C`ev_init\*(C'\fR for you, which means you have to call the |
1818 | automatically associates the default loop with this watcher. |
2959 | \&\f(CW\*(C`set\*(C'\fR method before starting it. |
|
|
2960 | .Sp |
|
|
2961 | It will not set a callback, however: You have to call the templated \f(CW\*(C`set\*(C'\fR |
|
|
2962 | method to set a callback before you can start the watcher. |
|
|
2963 | .Sp |
|
|
2964 | (The reason why you have to use a method is a limitation in \*(C+ which does |
|
|
2965 | not allow explicit template arguments for constructors). |
1819 | .Sp |
2966 | .Sp |
1820 | The destructor automatically stops the watcher if it is active. |
2967 | The destructor automatically stops the watcher if it is active. |
|
|
2968 | .IP "w\->set<class, &class::method> (object *)" 4 |
|
|
2969 | .IX Item "w->set<class, &class::method> (object *)" |
|
|
2970 | This method sets the callback method to call. The method has to have a |
|
|
2971 | signature of \f(CW\*(C`void (*)(ev_TYPE &, int)\*(C'\fR, it receives the watcher as |
|
|
2972 | first argument and the \f(CW\*(C`revents\*(C'\fR as second. The object must be given as |
|
|
2973 | parameter and is stored in the \f(CW\*(C`data\*(C'\fR member of the watcher. |
|
|
2974 | .Sp |
|
|
2975 | This method synthesizes efficient thunking code to call your method from |
|
|
2976 | the C callback that libev requires. If your compiler can inline your |
|
|
2977 | callback (i.e. it is visible to it at the place of the \f(CW\*(C`set\*(C'\fR call and |
|
|
2978 | your compiler is good :), then the method will be fully inlined into the |
|
|
2979 | thunking function, making it as fast as a direct C callback. |
|
|
2980 | .Sp |
|
|
2981 | Example: simple class declaration and watcher initialisation |
|
|
2982 | .Sp |
|
|
2983 | .Vb 4 |
|
|
2984 | \& struct myclass |
|
|
2985 | \& { |
|
|
2986 | \& void io_cb (ev::io &w, int revents) { } |
|
|
2987 | \& } |
|
|
2988 | \& |
|
|
2989 | \& myclass obj; |
|
|
2990 | \& ev::io iow; |
|
|
2991 | \& iow.set <myclass, &myclass::io_cb> (&obj); |
|
|
2992 | .Ve |
|
|
2993 | .IP "w\->set<function> (void *data = 0)" 4 |
|
|
2994 | .IX Item "w->set<function> (void *data = 0)" |
|
|
2995 | Also sets a callback, but uses a static method or plain function as |
|
|
2996 | callback. The optional \f(CW\*(C`data\*(C'\fR argument will be stored in the watcher's |
|
|
2997 | \&\f(CW\*(C`data\*(C'\fR member and is free for you to use. |
|
|
2998 | .Sp |
|
|
2999 | The prototype of the \f(CW\*(C`function\*(C'\fR must be \f(CW\*(C`void (*)(ev::TYPE &w, int)\*(C'\fR. |
|
|
3000 | .Sp |
|
|
3001 | See the method\-\f(CW\*(C`set\*(C'\fR above for more details. |
|
|
3002 | .Sp |
|
|
3003 | Example: Use a plain function as callback. |
|
|
3004 | .Sp |
|
|
3005 | .Vb 2 |
|
|
3006 | \& static void io_cb (ev::io &w, int revents) { } |
|
|
3007 | \& iow.set <io_cb> (); |
|
|
3008 | .Ve |
1821 | .IP "w\->set (struct ev_loop *)" 4 |
3009 | .IP "w\->set (struct ev_loop *)" 4 |
1822 | .IX Item "w->set (struct ev_loop *)" |
3010 | .IX Item "w->set (struct ev_loop *)" |
1823 | Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only |
3011 | Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only |
1824 | do this when the watcher is inactive (and not pending either). |
3012 | do this when the watcher is inactive (and not pending either). |
1825 | .IP "w\->set ([args])" 4 |
3013 | .IP "w\->set ([arguments])" 4 |
1826 | .IX Item "w->set ([args])" |
3014 | .IX Item "w->set ([arguments])" |
1827 | Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same args. Must be |
3015 | Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same arguments. Must be |
1828 | called at least once. Unlike the C counterpart, an active watcher gets |
3016 | called at least once. Unlike the C counterpart, an active watcher gets |
1829 | automatically stopped and restarted. |
3017 | automatically stopped and restarted when reconfiguring it with this |
|
|
3018 | method. |
1830 | .IP "w\->start ()" 4 |
3019 | .IP "w\->start ()" 4 |
1831 | .IX Item "w->start ()" |
3020 | .IX Item "w->start ()" |
1832 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument as the |
3021 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the |
1833 | constructor already takes the loop. |
3022 | constructor already stores the event loop. |
1834 | .IP "w\->stop ()" 4 |
3023 | .IP "w\->stop ()" 4 |
1835 | .IX Item "w->stop ()" |
3024 | .IX Item "w->stop ()" |
1836 | Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. |
3025 | Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. |
1837 | .ie n .IP "w\->again () ""ev::timer""\fR, \f(CW""ev::periodic"" only" 4 |
3026 | .ie n .IP "w\->again () (""ev::timer""\fR, \f(CW""ev::periodic"" only)" 4 |
1838 | .el .IP "w\->again () \f(CWev::timer\fR, \f(CWev::periodic\fR only" 4 |
3027 | .el .IP "w\->again () (\f(CWev::timer\fR, \f(CWev::periodic\fR only)" 4 |
1839 | .IX Item "w->again () ev::timer, ev::periodic only" |
3028 | .IX Item "w->again () (ev::timer, ev::periodic only)" |
1840 | For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding |
3029 | For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding |
1841 | \&\f(CW\*(C`ev_TYPE_again\*(C'\fR function. |
3030 | \&\f(CW\*(C`ev_TYPE_again\*(C'\fR function. |
1842 | .ie n .IP "w\->sweep () ""ev::embed"" only" 4 |
3031 | .ie n .IP "w\->sweep () (""ev::embed"" only)" 4 |
1843 | .el .IP "w\->sweep () \f(CWev::embed\fR only" 4 |
3032 | .el .IP "w\->sweep () (\f(CWev::embed\fR only)" 4 |
1844 | .IX Item "w->sweep () ev::embed only" |
3033 | .IX Item "w->sweep () (ev::embed only)" |
1845 | Invokes \f(CW\*(C`ev_embed_sweep\*(C'\fR. |
3034 | Invokes \f(CW\*(C`ev_embed_sweep\*(C'\fR. |
1846 | .ie n .IP "w\->update () ""ev::stat"" only" 4 |
3035 | .ie n .IP "w\->update () (""ev::stat"" only)" 4 |
1847 | .el .IP "w\->update () \f(CWev::stat\fR only" 4 |
3036 | .el .IP "w\->update () (\f(CWev::stat\fR only)" 4 |
1848 | .IX Item "w->update () ev::stat only" |
3037 | .IX Item "w->update () (ev::stat only)" |
1849 | Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR. |
3038 | Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR. |
1850 | .RE |
3039 | .RE |
1851 | .RS 4 |
3040 | .RS 4 |
1852 | .RE |
3041 | .RE |
1853 | .PP |
3042 | .PP |
1854 | Example: Define a class with an \s-1IO\s0 and idle watcher, start one of them in |
3043 | Example: Define a class with an \s-1IO\s0 and idle watcher, start one of them in |
1855 | the constructor. |
3044 | the constructor. |
1856 | .PP |
3045 | .PP |
1857 | .Vb 4 |
3046 | .Vb 4 |
1858 | \& class myclass |
3047 | \& class myclass |
1859 | \& { |
3048 | \& { |
1860 | \& ev_io io; void io_cb (ev::io &w, int revents); |
3049 | \& ev::io io ; void io_cb (ev::io &w, int revents); |
1861 | \& ev_idle idle void idle_cb (ev::idle &w, int revents); |
3050 | \& ev::idle idle; void idle_cb (ev::idle &w, int revents); |
1862 | .Ve |
3051 | \& |
1863 | .PP |
|
|
1864 | .Vb 2 |
|
|
1865 | \& myclass (); |
3052 | \& myclass (int fd) |
1866 | \& } |
|
|
1867 | .Ve |
|
|
1868 | .PP |
|
|
1869 | .Vb 6 |
|
|
1870 | \& myclass::myclass (int fd) |
|
|
1871 | \& : io (this, &myclass::io_cb), |
|
|
1872 | \& idle (this, &myclass::idle_cb) |
|
|
1873 | \& { |
3053 | \& { |
|
|
3054 | \& io .set <myclass, &myclass::io_cb > (this); |
|
|
3055 | \& idle.set <myclass, &myclass::idle_cb> (this); |
|
|
3056 | \& |
1874 | \& io.start (fd, ev::READ); |
3057 | \& io.start (fd, ev::READ); |
|
|
3058 | \& } |
1875 | \& } |
3059 | \& }; |
1876 | .Ve |
3060 | .Ve |
|
|
3061 | .SH "OTHER LANGUAGE BINDINGS" |
|
|
3062 | .IX Header "OTHER LANGUAGE BINDINGS" |
|
|
3063 | Libev does not offer other language bindings itself, but bindings for a |
|
|
3064 | number of languages exist in the form of third-party packages. If you know |
|
|
3065 | any interesting language binding in addition to the ones listed here, drop |
|
|
3066 | me a note. |
|
|
3067 | .IP "Perl" 4 |
|
|
3068 | .IX Item "Perl" |
|
|
3069 | The \s-1EV\s0 module implements the full libev \s-1API\s0 and is actually used to test |
|
|
3070 | libev. \s-1EV\s0 is developed together with libev. Apart from the \s-1EV\s0 core module, |
|
|
3071 | there are additional modules that implement libev-compatible interfaces |
|
|
3072 | to \f(CW\*(C`libadns\*(C'\fR (\f(CW\*(C`EV::ADNS\*(C'\fR, but \f(CW\*(C`AnyEvent::DNS\*(C'\fR is preferred nowadays), |
|
|
3073 | \&\f(CW\*(C`Net::SNMP\*(C'\fR (\f(CW\*(C`Net::SNMP::EV\*(C'\fR) and the \f(CW\*(C`libglib\*(C'\fR event core (\f(CW\*(C`Glib::EV\*(C'\fR |
|
|
3074 | and \f(CW\*(C`EV::Glib\*(C'\fR). |
|
|
3075 | .Sp |
|
|
3076 | It can be found and installed via \s-1CPAN\s0, its homepage is at |
|
|
3077 | <http://software.schmorp.de/pkg/EV>. |
|
|
3078 | .IP "Python" 4 |
|
|
3079 | .IX Item "Python" |
|
|
3080 | Python bindings can be found at <http://code.google.com/p/pyev/>. It |
|
|
3081 | seems to be quite complete and well-documented. Note, however, that the |
|
|
3082 | patch they require for libev is outright dangerous as it breaks the \s-1ABI\s0 |
|
|
3083 | for everybody else, and therefore, should never be applied in an installed |
|
|
3084 | libev (if python requires an incompatible \s-1ABI\s0 then it needs to embed |
|
|
3085 | libev). |
|
|
3086 | .IP "Ruby" 4 |
|
|
3087 | .IX Item "Ruby" |
|
|
3088 | Tony Arcieri has written a ruby extension that offers access to a subset |
|
|
3089 | of the libev \s-1API\s0 and adds file handle abstractions, asynchronous \s-1DNS\s0 and |
|
|
3090 | more on top of it. It can be found via gem servers. Its homepage is at |
|
|
3091 | <http://rev.rubyforge.org/>. |
|
|
3092 | .IP "D" 4 |
|
|
3093 | .IX Item "D" |
|
|
3094 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
|
|
3095 | be found at <http://proj.llucax.com.ar/wiki/evd>. |
|
|
3096 | .IP "Ocaml" 4 |
|
|
3097 | .IX Item "Ocaml" |
|
|
3098 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
|
|
3099 | <http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/>. |
1877 | .SH "MACRO MAGIC" |
3100 | .SH "MACRO MAGIC" |
1878 | .IX Header "MACRO MAGIC" |
3101 | .IX Header "MACRO MAGIC" |
1879 | Libev can be compiled with a variety of options, the most fundemantal is |
3102 | Libev can be compiled with a variety of options, the most fundamental |
1880 | \&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines wether (most) functions and |
3103 | of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) |
1881 | callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
3104 | functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
1882 | .PP |
3105 | .PP |
1883 | To make it easier to write programs that cope with either variant, the |
3106 | To make it easier to write programs that cope with either variant, the |
1884 | following macros are defined: |
3107 | following macros are defined: |
1885 | .ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4 |
3108 | .ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4 |
1886 | .el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4 |
3109 | .el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4 |
… | |
… | |
1888 | This provides the loop \fIargument\fR for functions, if one is required (\*(L"ev |
3111 | This provides the loop \fIargument\fR for functions, if one is required (\*(L"ev |
1889 | loop argument\*(R"). The \f(CW\*(C`EV_A\*(C'\fR form is used when this is the sole argument, |
3112 | loop argument\*(R"). The \f(CW\*(C`EV_A\*(C'\fR form is used when this is the sole argument, |
1890 | \&\f(CW\*(C`EV_A_\*(C'\fR is used when other arguments are following. Example: |
3113 | \&\f(CW\*(C`EV_A_\*(C'\fR is used when other arguments are following. Example: |
1891 | .Sp |
3114 | .Sp |
1892 | .Vb 3 |
3115 | .Vb 3 |
1893 | \& ev_unref (EV_A); |
3116 | \& ev_unref (EV_A); |
1894 | \& ev_timer_add (EV_A_ watcher); |
3117 | \& ev_timer_add (EV_A_ watcher); |
1895 | \& ev_loop (EV_A_ 0); |
3118 | \& ev_loop (EV_A_ 0); |
1896 | .Ve |
3119 | .Ve |
1897 | .Sp |
3120 | .Sp |
1898 | It assumes the variable \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR is in scope, |
3121 | It assumes the variable \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR is in scope, |
1899 | which is often provided by the following macro. |
3122 | which is often provided by the following macro. |
1900 | .ie n .IP """EV_P""\fR, \f(CW""EV_P_""" 4 |
3123 | .ie n .IP """EV_P""\fR, \f(CW""EV_P_""" 4 |
… | |
… | |
1903 | This provides the loop \fIparameter\fR for functions, if one is required (\*(L"ev |
3126 | This provides the loop \fIparameter\fR for functions, if one is required (\*(L"ev |
1904 | loop parameter\*(R"). The \f(CW\*(C`EV_P\*(C'\fR form is used when this is the sole parameter, |
3127 | loop parameter\*(R"). The \f(CW\*(C`EV_P\*(C'\fR form is used when this is the sole parameter, |
1905 | \&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example: |
3128 | \&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example: |
1906 | .Sp |
3129 | .Sp |
1907 | .Vb 2 |
3130 | .Vb 2 |
1908 | \& // this is how ev_unref is being declared |
3131 | \& // this is how ev_unref is being declared |
1909 | \& static void ev_unref (EV_P); |
3132 | \& static void ev_unref (EV_P); |
1910 | .Ve |
3133 | \& |
1911 | .Sp |
|
|
1912 | .Vb 2 |
|
|
1913 | \& // this is how you can declare your typical callback |
3134 | \& // this is how you can declare your typical callback |
1914 | \& static void cb (EV_P_ ev_timer *w, int revents) |
3135 | \& static void cb (EV_P_ ev_timer *w, int revents) |
1915 | .Ve |
3136 | .Ve |
1916 | .Sp |
3137 | .Sp |
1917 | It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite |
3138 | It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite |
1918 | suitable for use with \f(CW\*(C`EV_A\*(C'\fR. |
3139 | suitable for use with \f(CW\*(C`EV_A\*(C'\fR. |
1919 | .ie n .IP """EV_DEFAULT""\fR, \f(CW""EV_DEFAULT_""" 4 |
3140 | .ie n .IP """EV_DEFAULT""\fR, \f(CW""EV_DEFAULT_""" 4 |
1920 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
3141 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
1921 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
3142 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
1922 | Similar to the other two macros, this gives you the value of the default |
3143 | Similar to the other two macros, this gives you the value of the default |
1923 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). |
3144 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). |
|
|
3145 | .ie n .IP """EV_DEFAULT_UC""\fR, \f(CW""EV_DEFAULT_UC_""" 4 |
|
|
3146 | .el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4 |
|
|
3147 | .IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_" |
|
|
3148 | Usage identical to \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR, but requires that the |
|
|
3149 | default loop has been initialised (\f(CW\*(C`UC\*(C'\fR == unchecked). Their behaviour |
|
|
3150 | is undefined when the default loop has not been initialised by a previous |
|
|
3151 | 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. |
|
|
3152 | .Sp |
|
|
3153 | It is often prudent to use \f(CW\*(C`EV_DEFAULT\*(C'\fR when initialising the first |
|
|
3154 | watcher in a function but use \f(CW\*(C`EV_DEFAULT_UC\*(C'\fR afterwards. |
1924 | .PP |
3155 | .PP |
1925 | Example: Declare and initialise a check watcher, working regardless of |
3156 | Example: Declare and initialise a check watcher, utilising the above |
1926 | wether multiple loops are supported or not. |
3157 | macros so it will work regardless of whether multiple loops are supported |
|
|
3158 | or not. |
1927 | .PP |
3159 | .PP |
1928 | .Vb 5 |
3160 | .Vb 5 |
1929 | \& static void |
3161 | \& static void |
1930 | \& check_cb (EV_P_ ev_timer *w, int revents) |
3162 | \& check_cb (EV_P_ ev_timer *w, int revents) |
1931 | \& { |
3163 | \& { |
1932 | \& ev_check_stop (EV_A_ w); |
3164 | \& ev_check_stop (EV_A_ w); |
1933 | \& } |
3165 | \& } |
1934 | .Ve |
3166 | \& |
1935 | .PP |
|
|
1936 | .Vb 4 |
|
|
1937 | \& ev_check check; |
3167 | \& ev_check check; |
1938 | \& ev_check_init (&check, check_cb); |
3168 | \& ev_check_init (&check, check_cb); |
1939 | \& ev_check_start (EV_DEFAULT_ &check); |
3169 | \& ev_check_start (EV_DEFAULT_ &check); |
1940 | \& ev_loop (EV_DEFAULT_ 0); |
3170 | \& ev_loop (EV_DEFAULT_ 0); |
1941 | .Ve |
3171 | .Ve |
1942 | .SH "EMBEDDING" |
3172 | .SH "EMBEDDING" |
1943 | .IX Header "EMBEDDING" |
3173 | .IX Header "EMBEDDING" |
1944 | Libev can (and often is) directly embedded into host |
3174 | Libev can (and often is) directly embedded into host |
1945 | applications. Examples of applications that embed it include the Deliantra |
3175 | applications. Examples of applications that embed it include the Deliantra |
1946 | Game Server, the \s-1EV\s0 perl module, the \s-1GNU\s0 Virtual Private Ethernet (gvpe) |
3176 | Game Server, the \s-1EV\s0 perl module, the \s-1GNU\s0 Virtual Private Ethernet (gvpe) |
1947 | and rxvt\-unicode. |
3177 | and rxvt-unicode. |
1948 | .PP |
3178 | .PP |
1949 | The goal is to enable you to just copy the neecssary files into your |
3179 | The goal is to enable you to just copy the necessary files into your |
1950 | source directory without having to change even a single line in them, so |
3180 | source directory without having to change even a single line in them, so |
1951 | you can easily upgrade by simply copying (or having a checked-out copy of |
3181 | you can easily upgrade by simply copying (or having a checked-out copy of |
1952 | libev somewhere in your source tree). |
3182 | libev somewhere in your source tree). |
1953 | .Sh "\s-1FILESETS\s0" |
3183 | .Sh "\s-1FILESETS\s0" |
1954 | .IX Subsection "FILESETS" |
3184 | .IX Subsection "FILESETS" |
1955 | Depending on what features you need you need to include one or more sets of files |
3185 | Depending on what features you need you need to include one or more sets of files |
1956 | in your app. |
3186 | in your application. |
1957 | .PP |
3187 | .PP |
1958 | \fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR |
3188 | \fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR |
1959 | .IX Subsection "CORE EVENT LOOP" |
3189 | .IX Subsection "CORE EVENT LOOP" |
1960 | .PP |
3190 | .PP |
1961 | To include only the libev core (all the \f(CW\*(C`ev_*\*(C'\fR functions), with manual |
3191 | To include only the libev core (all the \f(CW\*(C`ev_*\*(C'\fR functions), with manual |
1962 | configuration (no autoconf): |
3192 | configuration (no autoconf): |
1963 | .PP |
3193 | .PP |
1964 | .Vb 2 |
3194 | .Vb 2 |
1965 | \& #define EV_STANDALONE 1 |
3195 | \& #define EV_STANDALONE 1 |
1966 | \& #include "ev.c" |
3196 | \& #include "ev.c" |
1967 | .Ve |
3197 | .Ve |
1968 | .PP |
3198 | .PP |
1969 | This will automatically include \fIev.h\fR, too, and should be done in a |
3199 | This will automatically include \fIev.h\fR, too, and should be done in a |
1970 | single C source file only to provide the function implementations. To use |
3200 | single C source file only to provide the function implementations. To use |
1971 | it, do the same for \fIev.h\fR in all files wishing to use this \s-1API\s0 (best |
3201 | it, do the same for \fIev.h\fR in all files wishing to use this \s-1API\s0 (best |
1972 | done by writing a wrapper around \fIev.h\fR that you can include instead and |
3202 | done by writing a wrapper around \fIev.h\fR that you can include instead and |
1973 | where you can put other configuration options): |
3203 | where you can put other configuration options): |
1974 | .PP |
3204 | .PP |
1975 | .Vb 2 |
3205 | .Vb 2 |
1976 | \& #define EV_STANDALONE 1 |
3206 | \& #define EV_STANDALONE 1 |
1977 | \& #include "ev.h" |
3207 | \& #include "ev.h" |
1978 | .Ve |
3208 | .Ve |
1979 | .PP |
3209 | .PP |
1980 | Both header files and implementation files can be compiled with a \*(C+ |
3210 | Both header files and implementation files can be compiled with a \*(C+ |
1981 | compiler (at least, thats a stated goal, and breakage will be treated |
3211 | compiler (at least, that's a stated goal, and breakage will be treated |
1982 | as a bug). |
3212 | as a bug). |
1983 | .PP |
3213 | .PP |
1984 | You need the following files in your source tree, or in a directory |
3214 | You need the following files in your source tree, or in a directory |
1985 | in your include path (e.g. in libev/ when using \-Ilibev): |
3215 | in your include path (e.g. in libev/ when using \-Ilibev): |
1986 | .PP |
3216 | .PP |
1987 | .Vb 4 |
3217 | .Vb 4 |
1988 | \& ev.h |
3218 | \& ev.h |
1989 | \& ev.c |
3219 | \& ev.c |
1990 | \& ev_vars.h |
3220 | \& ev_vars.h |
1991 | \& ev_wrap.h |
3221 | \& ev_wrap.h |
1992 | .Ve |
3222 | \& |
1993 | .PP |
|
|
1994 | .Vb 1 |
|
|
1995 | \& ev_win32.c required on win32 platforms only |
3223 | \& ev_win32.c required on win32 platforms only |
1996 | .Ve |
3224 | \& |
1997 | .PP |
|
|
1998 | .Vb 5 |
|
|
1999 | \& ev_select.c only when select backend is enabled (which is by default) |
3225 | \& ev_select.c only when select backend is enabled (which is enabled by default) |
2000 | \& ev_poll.c only when poll backend is enabled (disabled by default) |
3226 | \& ev_poll.c only when poll backend is enabled (disabled by default) |
2001 | \& ev_epoll.c only when the epoll backend is enabled (disabled by default) |
3227 | \& ev_epoll.c only when the epoll backend is enabled (disabled by default) |
2002 | \& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
3228 | \& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
2003 | \& ev_port.c only when the solaris port backend is enabled (disabled by default) |
3229 | \& ev_port.c only when the solaris port backend is enabled (disabled by default) |
2004 | .Ve |
3230 | .Ve |
2005 | .PP |
3231 | .PP |
2006 | \&\fIev.c\fR includes the backend files directly when enabled, so you only need |
3232 | \&\fIev.c\fR includes the backend files directly when enabled, so you only need |
2007 | to compile this single file. |
3233 | to compile this single file. |
2008 | .PP |
3234 | .PP |
… | |
… | |
2010 | .IX Subsection "LIBEVENT COMPATIBILITY API" |
3236 | .IX Subsection "LIBEVENT COMPATIBILITY API" |
2011 | .PP |
3237 | .PP |
2012 | To include the libevent compatibility \s-1API\s0, also include: |
3238 | To include the libevent compatibility \s-1API\s0, also include: |
2013 | .PP |
3239 | .PP |
2014 | .Vb 1 |
3240 | .Vb 1 |
2015 | \& #include "event.c" |
3241 | \& #include "event.c" |
2016 | .Ve |
3242 | .Ve |
2017 | .PP |
3243 | .PP |
2018 | in the file including \fIev.c\fR, and: |
3244 | in the file including \fIev.c\fR, and: |
2019 | .PP |
3245 | .PP |
2020 | .Vb 1 |
3246 | .Vb 1 |
2021 | \& #include "event.h" |
3247 | \& #include "event.h" |
2022 | .Ve |
3248 | .Ve |
2023 | .PP |
3249 | .PP |
2024 | in the files that want to use the libevent \s-1API\s0. This also includes \fIev.h\fR. |
3250 | in the files that want to use the libevent \s-1API\s0. This also includes \fIev.h\fR. |
2025 | .PP |
3251 | .PP |
2026 | You need the following additional files for this: |
3252 | You need the following additional files for this: |
2027 | .PP |
3253 | .PP |
2028 | .Vb 2 |
3254 | .Vb 2 |
2029 | \& event.h |
3255 | \& event.h |
2030 | \& event.c |
3256 | \& event.c |
2031 | .Ve |
3257 | .Ve |
2032 | .PP |
3258 | .PP |
2033 | \fI\s-1AUTOCONF\s0 \s-1SUPPORT\s0\fR |
3259 | \fI\s-1AUTOCONF\s0 \s-1SUPPORT\s0\fR |
2034 | .IX Subsection "AUTOCONF SUPPORT" |
3260 | .IX Subsection "AUTOCONF SUPPORT" |
2035 | .PP |
3261 | .PP |
2036 | Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your config in |
3262 | Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your configuration in |
2037 | whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your |
3263 | whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your |
2038 | \&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then |
3264 | \&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then |
2039 | include \fIconfig.h\fR and configure itself accordingly. |
3265 | include \fIconfig.h\fR and configure itself accordingly. |
2040 | .PP |
3266 | .PP |
2041 | For this of course you need the m4 file: |
3267 | For this of course you need the m4 file: |
2042 | .PP |
3268 | .PP |
2043 | .Vb 1 |
3269 | .Vb 1 |
2044 | \& libev.m4 |
3270 | \& libev.m4 |
2045 | .Ve |
3271 | .Ve |
2046 | .Sh "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" |
3272 | .Sh "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" |
2047 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
3273 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
2048 | Libev can be configured via a variety of preprocessor symbols you have to define |
3274 | Libev can be configured via a variety of preprocessor symbols you have to |
2049 | before including any of its files. The default is not to build for multiplicity |
3275 | define before including any of its files. The default in the absence of |
2050 | and only include the select backend. |
3276 | autoconf is documented for every option. |
2051 | .IP "\s-1EV_STANDALONE\s0" 4 |
3277 | .IP "\s-1EV_STANDALONE\s0" 4 |
2052 | .IX Item "EV_STANDALONE" |
3278 | .IX Item "EV_STANDALONE" |
2053 | Must always be \f(CW1\fR if you do not use autoconf configuration, which |
3279 | Must always be \f(CW1\fR if you do not use autoconf configuration, which |
2054 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
3280 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
2055 | implementations for some libevent functions (such as logging, which is not |
3281 | implementations for some libevent functions (such as logging, which is not |
2056 | supported). It will also not define any of the structs usually found in |
3282 | supported). It will also not define any of the structs usually found in |
2057 | \&\fIevent.h\fR that are not directly supported by the libev core alone. |
3283 | \&\fIevent.h\fR that are not directly supported by the libev core alone. |
2058 | .IP "\s-1EV_USE_MONOTONIC\s0" 4 |
3284 | .IP "\s-1EV_USE_MONOTONIC\s0" 4 |
2059 | .IX Item "EV_USE_MONOTONIC" |
3285 | .IX Item "EV_USE_MONOTONIC" |
2060 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
3286 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
2061 | monotonic clock option at both compiletime and runtime. Otherwise no use |
3287 | monotonic clock option at both compile time and runtime. Otherwise no use |
2062 | of the monotonic clock option will be attempted. If you enable this, you |
3288 | of the monotonic clock option will be attempted. If you enable this, you |
2063 | usually have to link against librt or something similar. Enabling it when |
3289 | usually have to link against librt or something similar. Enabling it when |
2064 | the functionality isn't available is safe, though, althoguh you have |
3290 | the functionality isn't available is safe, though, although you have |
2065 | to make sure you link against any libraries where the \f(CW\*(C`clock_gettime\*(C'\fR |
3291 | to make sure you link against any libraries where the \f(CW\*(C`clock_gettime\*(C'\fR |
2066 | function is hiding in (often \fI\-lrt\fR). |
3292 | function is hiding in (often \fI\-lrt\fR). |
2067 | .IP "\s-1EV_USE_REALTIME\s0" 4 |
3293 | .IP "\s-1EV_USE_REALTIME\s0" 4 |
2068 | .IX Item "EV_USE_REALTIME" |
3294 | .IX Item "EV_USE_REALTIME" |
2069 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
3295 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
2070 | realtime clock option at compiletime (and assume its availability at |
3296 | real-time clock option at compile time (and assume its availability at |
2071 | runtime if successful). Otherwise no use of the realtime clock option will |
3297 | runtime if successful). Otherwise no use of the real-time clock option will |
2072 | be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR by \f(CW\*(C`clock_get |
3298 | be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR by \f(CW\*(C`clock_get |
2073 | (CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect correctness. See tzhe note about libraries |
3299 | (CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect correctness. See the |
2074 | in the description of \f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though. |
3300 | note about libraries in the description of \f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though. |
|
|
3301 | .IP "\s-1EV_USE_NANOSLEEP\s0" 4 |
|
|
3302 | .IX Item "EV_USE_NANOSLEEP" |
|
|
3303 | If defined to be \f(CW1\fR, libev will assume that \f(CW\*(C`nanosleep ()\*(C'\fR is available |
|
|
3304 | and will use it for delays. Otherwise it will use \f(CW\*(C`select ()\*(C'\fR. |
|
|
3305 | .IP "\s-1EV_USE_EVENTFD\s0" 4 |
|
|
3306 | .IX Item "EV_USE_EVENTFD" |
|
|
3307 | If defined to be \f(CW1\fR, then libev will assume that \f(CW\*(C`eventfd ()\*(C'\fR is |
|
|
3308 | available and will probe for kernel support at runtime. This will improve |
|
|
3309 | \&\f(CW\*(C`ev_signal\*(C'\fR and \f(CW\*(C`ev_async\*(C'\fR performance and reduce resource consumption. |
|
|
3310 | If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc |
|
|
3311 | 2.7 or newer, otherwise disabled. |
2075 | .IP "\s-1EV_USE_SELECT\s0" 4 |
3312 | .IP "\s-1EV_USE_SELECT\s0" 4 |
2076 | .IX Item "EV_USE_SELECT" |
3313 | .IX Item "EV_USE_SELECT" |
2077 | If undefined or defined to be \f(CW1\fR, libev will compile in support for the |
3314 | If undefined or defined to be \f(CW1\fR, libev will compile in support for the |
2078 | \&\f(CW\*(C`select\*(C'\fR(2) backend. No attempt at autodetection will be done: if no |
3315 | \&\f(CW\*(C`select\*(C'\fR(2) backend. No attempt at auto-detection will be done: if no |
2079 | other method takes over, select will be it. Otherwise the select backend |
3316 | other method takes over, select will be it. Otherwise the select backend |
2080 | will not be compiled in. |
3317 | will not be compiled in. |
2081 | .IP "\s-1EV_SELECT_USE_FD_SET\s0" 4 |
3318 | .IP "\s-1EV_SELECT_USE_FD_SET\s0" 4 |
2082 | .IX Item "EV_SELECT_USE_FD_SET" |
3319 | .IX Item "EV_SELECT_USE_FD_SET" |
2083 | If defined to \f(CW1\fR, then the select backend will use the system \f(CW\*(C`fd_set\*(C'\fR |
3320 | If defined to \f(CW1\fR, then the select backend will use the system \f(CW\*(C`fd_set\*(C'\fR |
2084 | structure. This is useful if libev doesn't compile due to a missing |
3321 | structure. This is useful if libev doesn't compile due to a missing |
2085 | \&\f(CW\*(C`NFDBITS\*(C'\fR or \f(CW\*(C`fd_mask\*(C'\fR definition or it misguesses the bitset layout on |
3322 | \&\f(CW\*(C`NFDBITS\*(C'\fR or \f(CW\*(C`fd_mask\*(C'\fR definition or it mis-guesses the bitset layout on |
2086 | exotic systems. This usually limits the range of file descriptors to some |
3323 | exotic systems. This usually limits the range of file descriptors to some |
2087 | low limit such as 1024 or might have other limitations (winsocket only |
3324 | low limit such as 1024 or might have other limitations (winsocket only |
2088 | allows 64 sockets). The \f(CW\*(C`FD_SETSIZE\*(C'\fR macro, set before compilation, might |
3325 | allows 64 sockets). The \f(CW\*(C`FD_SETSIZE\*(C'\fR macro, set before compilation, might |
2089 | influence the size of the \f(CW\*(C`fd_set\*(C'\fR used. |
3326 | influence the size of the \f(CW\*(C`fd_set\*(C'\fR used. |
2090 | .IP "\s-1EV_SELECT_IS_WINSOCKET\s0" 4 |
3327 | .IP "\s-1EV_SELECT_IS_WINSOCKET\s0" 4 |
… | |
… | |
2094 | wants osf handles on win32 (this is the case when the select to |
3331 | wants osf handles on win32 (this is the case when the select to |
2095 | be used is the winsock select). This means that it will call |
3332 | be used is the winsock select). This means that it will call |
2096 | \&\f(CW\*(C`_get_osfhandle\*(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise, |
3333 | \&\f(CW\*(C`_get_osfhandle\*(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise, |
2097 | it is assumed that all these functions actually work on fds, even |
3334 | it is assumed that all these functions actually work on fds, even |
2098 | on win32. Should not be defined on non\-win32 platforms. |
3335 | on win32. Should not be defined on non\-win32 platforms. |
|
|
3336 | .IP "\s-1EV_FD_TO_WIN32_HANDLE\s0" 4 |
|
|
3337 | .IX Item "EV_FD_TO_WIN32_HANDLE" |
|
|
3338 | If \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR is enabled, then libev needs a way to map |
|
|
3339 | file descriptors to socket handles. When not defining this symbol (the |
|
|
3340 | default), then libev will call \f(CW\*(C`_get_osfhandle\*(C'\fR, which is usually |
|
|
3341 | correct. In some cases, programs use their own file descriptor management, |
|
|
3342 | in which case they can provide this function to map fds to socket handles. |
2099 | .IP "\s-1EV_USE_POLL\s0" 4 |
3343 | .IP "\s-1EV_USE_POLL\s0" 4 |
2100 | .IX Item "EV_USE_POLL" |
3344 | .IX Item "EV_USE_POLL" |
2101 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
3345 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
2102 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
3346 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
2103 | takes precedence over select. |
3347 | takes precedence over select. |
2104 | .IP "\s-1EV_USE_EPOLL\s0" 4 |
3348 | .IP "\s-1EV_USE_EPOLL\s0" 4 |
2105 | .IX Item "EV_USE_EPOLL" |
3349 | .IX Item "EV_USE_EPOLL" |
2106 | If defined to be \f(CW1\fR, libev will compile in support for the Linux |
3350 | If defined to be \f(CW1\fR, libev will compile in support for the Linux |
2107 | \&\f(CW\*(C`epoll\*(C'\fR(7) backend. Its availability will be detected at runtime, |
3351 | \&\f(CW\*(C`epoll\*(C'\fR(7) backend. Its availability will be detected at runtime, |
2108 | otherwise another method will be used as fallback. This is the |
3352 | otherwise another method will be used as fallback. This is the preferred |
2109 | preferred backend for GNU/Linux systems. |
3353 | backend for GNU/Linux systems. If undefined, it will be enabled if the |
|
|
3354 | headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
2110 | .IP "\s-1EV_USE_KQUEUE\s0" 4 |
3355 | .IP "\s-1EV_USE_KQUEUE\s0" 4 |
2111 | .IX Item "EV_USE_KQUEUE" |
3356 | .IX Item "EV_USE_KQUEUE" |
2112 | If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style |
3357 | If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style |
2113 | \&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime, |
3358 | \&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime, |
2114 | otherwise another method will be used as fallback. This is the preferred |
3359 | otherwise another method will be used as fallback. This is the preferred |
… | |
… | |
2124 | 10 port style backend. Its availability will be detected at runtime, |
3369 | 10 port style backend. Its availability will be detected at runtime, |
2125 | otherwise another method will be used as fallback. This is the preferred |
3370 | otherwise another method will be used as fallback. This is the preferred |
2126 | backend for Solaris 10 systems. |
3371 | backend for Solaris 10 systems. |
2127 | .IP "\s-1EV_USE_DEVPOLL\s0" 4 |
3372 | .IP "\s-1EV_USE_DEVPOLL\s0" 4 |
2128 | .IX Item "EV_USE_DEVPOLL" |
3373 | .IX Item "EV_USE_DEVPOLL" |
2129 | reserved for future expansion, works like the \s-1USE\s0 symbols above. |
3374 | Reserved for future expansion, works like the \s-1USE\s0 symbols above. |
|
|
3375 | .IP "\s-1EV_USE_INOTIFY\s0" 4 |
|
|
3376 | .IX Item "EV_USE_INOTIFY" |
|
|
3377 | If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify |
|
|
3378 | interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will |
|
|
3379 | be detected at runtime. If undefined, it will be enabled if the headers |
|
|
3380 | indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
|
|
3381 | .IP "\s-1EV_ATOMIC_T\s0" 4 |
|
|
3382 | .IX Item "EV_ATOMIC_T" |
|
|
3383 | Libev requires an integer type (suitable for storing \f(CW0\fR or \f(CW1\fR) whose |
|
|
3384 | access is atomic with respect to other threads or signal contexts. No such |
|
|
3385 | type is easily found in the C language, so you can provide your own type |
|
|
3386 | that you know is safe for your purposes. It is used both for signal handler \*(L"locking\*(R" |
|
|
3387 | as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR watchers. |
|
|
3388 | .Sp |
|
|
3389 | In the absence of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR |
|
|
3390 | (from \fIsignal.h\fR), which is usually good enough on most platforms. |
2130 | .IP "\s-1EV_H\s0" 4 |
3391 | .IP "\s-1EV_H\s0" 4 |
2131 | .IX Item "EV_H" |
3392 | .IX Item "EV_H" |
2132 | The name of the \fIev.h\fR header file used to include it. The default if |
3393 | The name of the \fIev.h\fR header file used to include it. The default if |
2133 | undefined is \f(CW\*(C`<ev.h>\*(C'\fR in \fIevent.h\fR and \f(CW"ev.h"\fR in \fIev.c\fR. This |
3394 | undefined is \f(CW"ev.h"\fR in \fIevent.h\fR, \fIev.c\fR and \fIev++.h\fR. This can be |
2134 | can be used to virtually rename the \fIev.h\fR header file in case of conflicts. |
3395 | used to virtually rename the \fIev.h\fR header file in case of conflicts. |
2135 | .IP "\s-1EV_CONFIG_H\s0" 4 |
3396 | .IP "\s-1EV_CONFIG_H\s0" 4 |
2136 | .IX Item "EV_CONFIG_H" |
3397 | .IX Item "EV_CONFIG_H" |
2137 | If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override |
3398 | If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override |
2138 | \&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to |
3399 | \&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to |
2139 | \&\f(CW\*(C`EV_H\*(C'\fR, above. |
3400 | \&\f(CW\*(C`EV_H\*(C'\fR, above. |
2140 | .IP "\s-1EV_EVENT_H\s0" 4 |
3401 | .IP "\s-1EV_EVENT_H\s0" 4 |
2141 | .IX Item "EV_EVENT_H" |
3402 | .IX Item "EV_EVENT_H" |
2142 | Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea |
3403 | Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea |
2143 | of how the \fIevent.h\fR header can be found. |
3404 | of how the \fIevent.h\fR header can be found, the default is \f(CW"event.h"\fR. |
2144 | .IP "\s-1EV_PROTOTYPES\s0" 4 |
3405 | .IP "\s-1EV_PROTOTYPES\s0" 4 |
2145 | .IX Item "EV_PROTOTYPES" |
3406 | .IX Item "EV_PROTOTYPES" |
2146 | If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function |
3407 | If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function |
2147 | prototypes, but still define all the structs and other symbols. This is |
3408 | prototypes, but still define all the structs and other symbols. This is |
2148 | occasionally useful if you want to provide your own wrapper functions |
3409 | occasionally useful if you want to provide your own wrapper functions |
… | |
… | |
2152 | If undefined or defined to \f(CW1\fR, then all event-loop-specific functions |
3413 | If undefined or defined to \f(CW1\fR, then all event-loop-specific functions |
2153 | will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create |
3414 | will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create |
2154 | additional independent event loops. Otherwise there will be no support |
3415 | additional independent event loops. Otherwise there will be no support |
2155 | for multiple event loops and there is no first event loop pointer |
3416 | for multiple event loops and there is no first event loop pointer |
2156 | argument. Instead, all functions act on the single default loop. |
3417 | argument. Instead, all functions act on the single default loop. |
|
|
3418 | .IP "\s-1EV_MINPRI\s0" 4 |
|
|
3419 | .IX Item "EV_MINPRI" |
|
|
3420 | .PD 0 |
|
|
3421 | .IP "\s-1EV_MAXPRI\s0" 4 |
|
|
3422 | .IX Item "EV_MAXPRI" |
|
|
3423 | .PD |
|
|
3424 | The range of allowed priorities. \f(CW\*(C`EV_MINPRI\*(C'\fR must be smaller or equal to |
|
|
3425 | \&\f(CW\*(C`EV_MAXPRI\*(C'\fR, but otherwise there are no non-obvious limitations. You can |
|
|
3426 | provide for more priorities by overriding those symbols (usually defined |
|
|
3427 | to be \f(CW\*(C`\-2\*(C'\fR and \f(CW2\fR, respectively). |
|
|
3428 | .Sp |
|
|
3429 | When doing priority-based operations, libev usually has to linearly search |
|
|
3430 | all the priorities, so having many of them (hundreds) uses a lot of space |
|
|
3431 | and time, so using the defaults of five priorities (\-2 .. +2) is usually |
|
|
3432 | fine. |
|
|
3433 | .Sp |
|
|
3434 | If your embedding application does not need any priorities, defining these |
|
|
3435 | both to \f(CW0\fR will save some memory and \s-1CPU\s0. |
2157 | .IP "\s-1EV_PERIODIC_ENABLE\s0" 4 |
3436 | .IP "\s-1EV_PERIODIC_ENABLE\s0" 4 |
2158 | .IX Item "EV_PERIODIC_ENABLE" |
3437 | .IX Item "EV_PERIODIC_ENABLE" |
2159 | If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If |
3438 | If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If |
2160 | defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of |
3439 | defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of |
2161 | code. |
3440 | code. |
|
|
3441 | .IP "\s-1EV_IDLE_ENABLE\s0" 4 |
|
|
3442 | .IX Item "EV_IDLE_ENABLE" |
|
|
3443 | If undefined or defined to be \f(CW1\fR, then idle watchers are supported. If |
|
|
3444 | defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of |
|
|
3445 | code. |
2162 | .IP "\s-1EV_EMBED_ENABLE\s0" 4 |
3446 | .IP "\s-1EV_EMBED_ENABLE\s0" 4 |
2163 | .IX Item "EV_EMBED_ENABLE" |
3447 | .IX Item "EV_EMBED_ENABLE" |
2164 | If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If |
3448 | If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If |
2165 | defined to be \f(CW0\fR, then they are not. |
3449 | defined to be \f(CW0\fR, then they are not. Embed watchers rely on most other |
|
|
3450 | watcher types, which therefore must not be disabled. |
2166 | .IP "\s-1EV_STAT_ENABLE\s0" 4 |
3451 | .IP "\s-1EV_STAT_ENABLE\s0" 4 |
2167 | .IX Item "EV_STAT_ENABLE" |
3452 | .IX Item "EV_STAT_ENABLE" |
2168 | If undefined or defined to be \f(CW1\fR, then stat watchers are supported. If |
3453 | If undefined or defined to be \f(CW1\fR, then stat watchers are supported. If |
2169 | defined to be \f(CW0\fR, then they are not. |
3454 | defined to be \f(CW0\fR, then they are not. |
2170 | .IP "\s-1EV_FORK_ENABLE\s0" 4 |
3455 | .IP "\s-1EV_FORK_ENABLE\s0" 4 |
2171 | .IX Item "EV_FORK_ENABLE" |
3456 | .IX Item "EV_FORK_ENABLE" |
2172 | If undefined or defined to be \f(CW1\fR, then fork watchers are supported. If |
3457 | If undefined or defined to be \f(CW1\fR, then fork watchers are supported. If |
2173 | defined to be \f(CW0\fR, then they are not. |
3458 | defined to be \f(CW0\fR, then they are not. |
|
|
3459 | .IP "\s-1EV_ASYNC_ENABLE\s0" 4 |
|
|
3460 | .IX Item "EV_ASYNC_ENABLE" |
|
|
3461 | If undefined or defined to be \f(CW1\fR, then async watchers are supported. If |
|
|
3462 | defined to be \f(CW0\fR, then they are not. |
2174 | .IP "\s-1EV_MINIMAL\s0" 4 |
3463 | .IP "\s-1EV_MINIMAL\s0" 4 |
2175 | .IX Item "EV_MINIMAL" |
3464 | .IX Item "EV_MINIMAL" |
2176 | If you need to shave off some kilobytes of code at the expense of some |
3465 | If you need to shave off some kilobytes of code at the expense of some |
2177 | speed, define this symbol to \f(CW1\fR. Currently only used for gcc to override |
3466 | speed, define this symbol to \f(CW1\fR. Currently this is used to override some |
2178 | some inlining decisions, saves roughly 30% codesize of amd64. |
3467 | inlining decisions, saves roughly 30% code size on amd64. It also selects a |
|
|
3468 | much smaller 2\-heap for timer management over the default 4\-heap. |
2179 | .IP "\s-1EV_PID_HASHSIZE\s0" 4 |
3469 | .IP "\s-1EV_PID_HASHSIZE\s0" 4 |
2180 | .IX Item "EV_PID_HASHSIZE" |
3470 | .IX Item "EV_PID_HASHSIZE" |
2181 | \&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by |
3471 | \&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by |
2182 | pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more |
3472 | pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more |
2183 | than enough. If you need to manage thousands of children you might want to |
3473 | than enough. If you need to manage thousands of children you might want to |
2184 | increase this value. |
3474 | increase this value (\fImust\fR be a power of two). |
|
|
3475 | .IP "\s-1EV_INOTIFY_HASHSIZE\s0" 4 |
|
|
3476 | .IX Item "EV_INOTIFY_HASHSIZE" |
|
|
3477 | \&\f(CW\*(C`ev_stat\*(C'\fR watchers use a small hash table to distribute workload by |
|
|
3478 | inotify watch id. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), |
|
|
3479 | usually more than enough. If you need to manage thousands of \f(CW\*(C`ev_stat\*(C'\fR |
|
|
3480 | watchers you might want to increase this value (\fImust\fR be a power of |
|
|
3481 | two). |
|
|
3482 | .IP "\s-1EV_USE_4HEAP\s0" 4 |
|
|
3483 | .IX Item "EV_USE_4HEAP" |
|
|
3484 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
|
|
3485 | timer and periodics heaps, libev uses a 4\-heap when this symbol is defined |
|
|
3486 | to \f(CW1\fR. The 4\-heap uses more complicated (longer) code but has noticeably |
|
|
3487 | faster performance with many (thousands) of watchers. |
|
|
3488 | .Sp |
|
|
3489 | The default is \f(CW1\fR unless \f(CW\*(C`EV_MINIMAL\*(C'\fR is set in which case it is \f(CW0\fR |
|
|
3490 | (disabled). |
|
|
3491 | .IP "\s-1EV_HEAP_CACHE_AT\s0" 4 |
|
|
3492 | .IX Item "EV_HEAP_CACHE_AT" |
|
|
3493 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
|
|
3494 | timer and periodics heaps, libev can cache the timestamp (\fIat\fR) within |
|
|
3495 | the heap structure (selected by defining \f(CW\*(C`EV_HEAP_CACHE_AT\*(C'\fR to \f(CW1\fR), |
|
|
3496 | which uses 8\-12 bytes more per watcher and a few hundred bytes more code, |
|
|
3497 | but avoids random read accesses on heap changes. This improves performance |
|
|
3498 | noticeably with many (hundreds) of watchers. |
|
|
3499 | .Sp |
|
|
3500 | The default is \f(CW1\fR unless \f(CW\*(C`EV_MINIMAL\*(C'\fR is set in which case it is \f(CW0\fR |
|
|
3501 | (disabled). |
|
|
3502 | .IP "\s-1EV_VERIFY\s0" 4 |
|
|
3503 | .IX Item "EV_VERIFY" |
|
|
3504 | Controls how much internal verification (see \f(CW\*(C`ev_loop_verify ()\*(C'\fR) will |
|
|
3505 | be done: If set to \f(CW0\fR, no internal verification code will be compiled |
|
|
3506 | in. If set to \f(CW1\fR, then verification code will be compiled in, but not |
|
|
3507 | called. If set to \f(CW2\fR, then the internal verification code will be |
|
|
3508 | called once per loop, which can slow down libev. If set to \f(CW3\fR, then the |
|
|
3509 | verification code will be called very frequently, which will slow down |
|
|
3510 | libev considerably. |
|
|
3511 | .Sp |
|
|
3512 | The default is \f(CW1\fR, unless \f(CW\*(C`EV_MINIMAL\*(C'\fR is set, in which case it will be |
|
|
3513 | \&\f(CW0\fR. |
2185 | .IP "\s-1EV_COMMON\s0" 4 |
3514 | .IP "\s-1EV_COMMON\s0" 4 |
2186 | .IX Item "EV_COMMON" |
3515 | .IX Item "EV_COMMON" |
2187 | By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining |
3516 | By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining |
2188 | this macro to a something else you can include more and other types of |
3517 | this macro to a something else you can include more and other types of |
2189 | members. You have to define it each time you include one of the files, |
3518 | members. You have to define it each time you include one of the files, |
2190 | though, and it must be identical each time. |
3519 | though, and it must be identical each time. |
2191 | .Sp |
3520 | .Sp |
2192 | For example, the perl \s-1EV\s0 module uses something like this: |
3521 | For example, the perl \s-1EV\s0 module uses something like this: |
2193 | .Sp |
3522 | .Sp |
2194 | .Vb 3 |
3523 | .Vb 3 |
2195 | \& #define EV_COMMON \e |
3524 | \& #define EV_COMMON \e |
2196 | \& SV *self; /* contains this struct */ \e |
3525 | \& SV *self; /* contains this struct */ \e |
2197 | \& SV *cb_sv, *fh /* note no trailing ";" */ |
3526 | \& SV *cb_sv, *fh /* note no trailing ";" */ |
2198 | .Ve |
3527 | .Ve |
2199 | .IP "\s-1EV_CB_DECLARE\s0 (type)" 4 |
3528 | .IP "\s-1EV_CB_DECLARE\s0 (type)" 4 |
2200 | .IX Item "EV_CB_DECLARE (type)" |
3529 | .IX Item "EV_CB_DECLARE (type)" |
2201 | .PD 0 |
3530 | .PD 0 |
2202 | .IP "\s-1EV_CB_INVOKE\s0 (watcher, revents)" 4 |
3531 | .IP "\s-1EV_CB_INVOKE\s0 (watcher, revents)" 4 |
… | |
… | |
2204 | .IP "ev_set_cb (ev, cb)" 4 |
3533 | .IP "ev_set_cb (ev, cb)" 4 |
2205 | .IX Item "ev_set_cb (ev, cb)" |
3534 | .IX Item "ev_set_cb (ev, cb)" |
2206 | .PD |
3535 | .PD |
2207 | Can be used to change the callback member declaration in each watcher, |
3536 | Can be used to change the callback member declaration in each watcher, |
2208 | and the way callbacks are invoked and set. Must expand to a struct member |
3537 | and the way callbacks are invoked and set. Must expand to a struct member |
2209 | definition and a statement, respectively. See the \fIev.v\fR header file for |
3538 | definition and a statement, respectively. See the \fIev.h\fR header file for |
2210 | their default definitions. One possible use for overriding these is to |
3539 | their default definitions. One possible use for overriding these is to |
2211 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
3540 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
2212 | method calls instead of plain function calls in \*(C+. |
3541 | method calls instead of plain function calls in \*(C+. |
|
|
3542 | .Sh "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0" |
|
|
3543 | .IX Subsection "EXPORTED API SYMBOLS" |
|
|
3544 | If you need to re-export the \s-1API\s0 (e.g. via a \s-1DLL\s0) and you need a list of |
|
|
3545 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
|
|
3546 | all public symbols, one per line: |
|
|
3547 | .PP |
|
|
3548 | .Vb 2 |
|
|
3549 | \& Symbols.ev for libev proper |
|
|
3550 | \& Symbols.event for the libevent emulation |
|
|
3551 | .Ve |
|
|
3552 | .PP |
|
|
3553 | This can also be used to rename all public symbols to avoid clashes with |
|
|
3554 | multiple versions of libev linked together (which is obviously bad in |
|
|
3555 | itself, but sometimes it is inconvenient to avoid this). |
|
|
3556 | .PP |
|
|
3557 | A sed command like this will create wrapper \f(CW\*(C`#define\*(C'\fR's that you need to |
|
|
3558 | include before including \fIev.h\fR: |
|
|
3559 | .PP |
|
|
3560 | .Vb 1 |
|
|
3561 | \& <Symbols.ev sed \-e "s/.*/#define & myprefix_&/" >wrap.h |
|
|
3562 | .Ve |
|
|
3563 | .PP |
|
|
3564 | This would create a file \fIwrap.h\fR which essentially looks like this: |
|
|
3565 | .PP |
|
|
3566 | .Vb 4 |
|
|
3567 | \& #define ev_backend myprefix_ev_backend |
|
|
3568 | \& #define ev_check_start myprefix_ev_check_start |
|
|
3569 | \& #define ev_check_stop myprefix_ev_check_stop |
|
|
3570 | \& ... |
|
|
3571 | .Ve |
2213 | .Sh "\s-1EXAMPLES\s0" |
3572 | .Sh "\s-1EXAMPLES\s0" |
2214 | .IX Subsection "EXAMPLES" |
3573 | .IX Subsection "EXAMPLES" |
2215 | For a real-world example of a program the includes libev |
3574 | For a real-world example of a program the includes libev |
2216 | verbatim, you can have a look at the \s-1EV\s0 perl module |
3575 | verbatim, you can have a look at the \s-1EV\s0 perl module |
2217 | (<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
3576 | (<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
2218 | the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public |
3577 | the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public |
2219 | interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file |
3578 | interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file |
2220 | will be compiled. It is pretty complex because it provides its own header |
3579 | will be compiled. It is pretty complex because it provides its own header |
2221 | file. |
3580 | file. |
2222 | .Sp |
3581 | .PP |
2223 | The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file |
3582 | The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file |
2224 | that everybody includes and which overrides some autoconf choices: |
3583 | that everybody includes and which overrides some configure choices: |
2225 | .Sp |
3584 | .PP |
2226 | .Vb 4 |
3585 | .Vb 9 |
|
|
3586 | \& #define EV_MINIMAL 1 |
2227 | \& #define EV_USE_POLL 0 |
3587 | \& #define EV_USE_POLL 0 |
2228 | \& #define EV_MULTIPLICITY 0 |
3588 | \& #define EV_MULTIPLICITY 0 |
2229 | \& #define EV_PERIODICS 0 |
3589 | \& #define EV_PERIODIC_ENABLE 0 |
|
|
3590 | \& #define EV_STAT_ENABLE 0 |
|
|
3591 | \& #define EV_FORK_ENABLE 0 |
2230 | \& #define EV_CONFIG_H <config.h> |
3592 | \& #define EV_CONFIG_H <config.h> |
2231 | .Ve |
3593 | \& #define EV_MINPRI 0 |
2232 | .Sp |
3594 | \& #define EV_MAXPRI 0 |
2233 | .Vb 1 |
3595 | \& |
2234 | \& #include "ev++.h" |
3596 | \& #include "ev++.h" |
2235 | .Ve |
3597 | .Ve |
2236 | .Sp |
3598 | .PP |
2237 | And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled: |
3599 | And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled: |
2238 | .Sp |
3600 | .PP |
2239 | .Vb 2 |
3601 | .Vb 2 |
2240 | \& #include "ev_cpp.h" |
3602 | \& #include "ev_cpp.h" |
2241 | \& #include "ev.c" |
3603 | \& #include "ev.c" |
2242 | .Ve |
3604 | .Ve |
|
|
3605 | .SH "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES" |
|
|
3606 | .IX Header "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES" |
|
|
3607 | .Sh "\s-1THREADS\s0 \s-1AND\s0 \s-1COROUTINES\s0" |
|
|
3608 | .IX Subsection "THREADS AND COROUTINES" |
|
|
3609 | \fI\s-1THREADS\s0\fR |
|
|
3610 | .IX Subsection "THREADS" |
|
|
3611 | .PP |
|
|
3612 | All libev functions are reentrant and thread-safe unless explicitly |
|
|
3613 | documented otherwise, but libev implements no locking itself. This means |
|
|
3614 | that you can use as many loops as you want in parallel, as long as there |
|
|
3615 | are no concurrent calls into any libev function with the same loop |
|
|
3616 | parameter (\f(CW\*(C`ev_default_*\*(C'\fR calls have an implicit default loop parameter, |
|
|
3617 | of course): libev guarantees that different event loops share no data |
|
|
3618 | structures that need any locking. |
|
|
3619 | .PP |
|
|
3620 | Or to put it differently: calls with different loop parameters can be done |
|
|
3621 | concurrently from multiple threads, calls with the same loop parameter |
|
|
3622 | must be done serially (but can be done from different threads, as long as |
|
|
3623 | only one thread ever is inside a call at any point in time, e.g. by using |
|
|
3624 | a mutex per loop). |
|
|
3625 | .PP |
|
|
3626 | Specifically to support threads (and signal handlers), libev implements |
|
|
3627 | so-called \f(CW\*(C`ev_async\*(C'\fR watchers, which allow some limited form of |
|
|
3628 | concurrency on the same event loop, namely waking it up \*(L"from the |
|
|
3629 | outside\*(R". |
|
|
3630 | .PP |
|
|
3631 | If you want to know which design (one loop, locking, or multiple loops |
|
|
3632 | without or something else still) is best for your problem, then I cannot |
|
|
3633 | help you, but here is some generic advice: |
|
|
3634 | .IP "\(bu" 4 |
|
|
3635 | most applications have a main thread: use the default libev loop |
|
|
3636 | in that thread, or create a separate thread running only the default loop. |
|
|
3637 | .Sp |
|
|
3638 | This helps integrating other libraries or software modules that use libev |
|
|
3639 | themselves and don't care/know about threading. |
|
|
3640 | .IP "\(bu" 4 |
|
|
3641 | one loop per thread is usually a good model. |
|
|
3642 | .Sp |
|
|
3643 | Doing this is almost never wrong, sometimes a better-performance model |
|
|
3644 | exists, but it is always a good start. |
|
|
3645 | .IP "\(bu" 4 |
|
|
3646 | other models exist, such as the leader/follower pattern, where one |
|
|
3647 | loop is handed through multiple threads in a kind of round-robin fashion. |
|
|
3648 | .Sp |
|
|
3649 | Choosing a model is hard \- look around, learn, know that usually you can do |
|
|
3650 | better than you currently do :\-) |
|
|
3651 | .IP "\(bu" 4 |
|
|
3652 | often you need to talk to some other thread which blocks in the |
|
|
3653 | event loop. |
|
|
3654 | .Sp |
|
|
3655 | \&\f(CW\*(C`ev_async\*(C'\fR watchers can be used to wake them up from other threads safely |
|
|
3656 | (or from signal contexts...). |
|
|
3657 | .Sp |
|
|
3658 | An example use would be to communicate signals or other events that only |
|
|
3659 | work in the default loop by registering the signal watcher with the |
|
|
3660 | default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop |
|
|
3661 | watcher callback into the event loop interested in the signal. |
|
|
3662 | .PP |
|
|
3663 | \fI\s-1COROUTINES\s0\fR |
|
|
3664 | .IX Subsection "COROUTINES" |
|
|
3665 | .PP |
|
|
3666 | Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"): |
|
|
3667 | libev fully supports nesting calls to its functions from different |
|
|
3668 | coroutines (e.g. you can call \f(CW\*(C`ev_loop\*(C'\fR on the same loop from two |
|
|
3669 | different coroutines, and switch freely between both coroutines running the |
|
|
3670 | loop, as long as you don't confuse yourself). The only exception is that |
|
|
3671 | you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. |
|
|
3672 | .PP |
|
|
3673 | Care has been taken to ensure that libev does not keep local state inside |
|
|
3674 | \&\f(CW\*(C`ev_loop\*(C'\fR, and other calls do not usually allow for coroutine switches as |
|
|
3675 | they do not call any callbacks. |
|
|
3676 | .Sh "\s-1COMPILER\s0 \s-1WARNINGS\s0" |
|
|
3677 | .IX Subsection "COMPILER WARNINGS" |
|
|
3678 | Depending on your compiler and compiler settings, you might get no or a |
|
|
3679 | lot of warnings when compiling libev code. Some people are apparently |
|
|
3680 | scared by this. |
|
|
3681 | .PP |
|
|
3682 | However, these are unavoidable for many reasons. For one, each compiler |
|
|
3683 | has different warnings, and each user has different tastes regarding |
|
|
3684 | warning options. \*(L"Warn-free\*(R" code therefore cannot be a goal except when |
|
|
3685 | targeting a specific compiler and compiler-version. |
|
|
3686 | .PP |
|
|
3687 | Another reason is that some compiler warnings require elaborate |
|
|
3688 | workarounds, or other changes to the code that make it less clear and less |
|
|
3689 | maintainable. |
|
|
3690 | .PP |
|
|
3691 | And of course, some compiler warnings are just plain stupid, or simply |
|
|
3692 | wrong (because they don't actually warn about the condition their message |
|
|
3693 | seems to warn about). For example, certain older gcc versions had some |
|
|
3694 | warnings that resulted an extreme number of false positives. These have |
|
|
3695 | been fixed, but some people still insist on making code warn-free with |
|
|
3696 | such buggy versions. |
|
|
3697 | .PP |
|
|
3698 | While libev is written to generate as few warnings as possible, |
|
|
3699 | \&\*(L"warn-free\*(R" code is not a goal, and it is recommended not to build libev |
|
|
3700 | with any compiler warnings enabled unless you are prepared to cope with |
|
|
3701 | them (e.g. by ignoring them). Remember that warnings are just that: |
|
|
3702 | warnings, not errors, or proof of bugs. |
|
|
3703 | .Sh "\s-1VALGRIND\s0" |
|
|
3704 | .IX Subsection "VALGRIND" |
|
|
3705 | Valgrind has a special section here because it is a popular tool that is |
|
|
3706 | highly useful. Unfortunately, valgrind reports are very hard to interpret. |
|
|
3707 | .PP |
|
|
3708 | If you think you found a bug (memory leak, uninitialised data access etc.) |
|
|
3709 | in libev, then check twice: If valgrind reports something like: |
|
|
3710 | .PP |
|
|
3711 | .Vb 3 |
|
|
3712 | \& ==2274== definitely lost: 0 bytes in 0 blocks. |
|
|
3713 | \& ==2274== possibly lost: 0 bytes in 0 blocks. |
|
|
3714 | \& ==2274== still reachable: 256 bytes in 1 blocks. |
|
|
3715 | .Ve |
|
|
3716 | .PP |
|
|
3717 | Then there is no memory leak, just as memory accounted to global variables |
|
|
3718 | is not a memleak \- the memory is still being referenced, and didn't leak. |
|
|
3719 | .PP |
|
|
3720 | Similarly, under some circumstances, valgrind might report kernel bugs |
|
|
3721 | as if it were a bug in libev (e.g. in realloc or in the poll backend, |
|
|
3722 | although an acceptable workaround has been found here), or it might be |
|
|
3723 | confused. |
|
|
3724 | .PP |
|
|
3725 | Keep in mind that valgrind is a very good tool, but only a tool. Don't |
|
|
3726 | make it into some kind of religion. |
|
|
3727 | .PP |
|
|
3728 | If you are unsure about something, feel free to contact the mailing list |
|
|
3729 | with the full valgrind report and an explanation on why you think this |
|
|
3730 | is a bug in libev (best check the archives, too :). However, don't be |
|
|
3731 | annoyed when you get a brisk \*(L"this is no bug\*(R" answer and take the chance |
|
|
3732 | of learning how to interpret valgrind properly. |
|
|
3733 | .PP |
|
|
3734 | If you need, for some reason, empty reports from valgrind for your project |
|
|
3735 | I suggest using suppression lists. |
|
|
3736 | .SH "PORTABILITY NOTES" |
|
|
3737 | .IX Header "PORTABILITY NOTES" |
|
|
3738 | .Sh "\s-1WIN32\s0 \s-1PLATFORM\s0 \s-1LIMITATIONS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" |
|
|
3739 | .IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS" |
|
|
3740 | Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev |
|
|
3741 | requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 |
|
|
3742 | model. Libev still offers limited functionality on this platform in |
|
|
3743 | the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket |
|
|
3744 | descriptors. This only applies when using Win32 natively, not when using |
|
|
3745 | e.g. cygwin. |
|
|
3746 | .PP |
|
|
3747 | Lifting these limitations would basically require the full |
|
|
3748 | re-implementation of the I/O system. If you are into these kinds of |
|
|
3749 | things, then note that glib does exactly that for you in a very portable |
|
|
3750 | way (note also that glib is the slowest event library known to man). |
|
|
3751 | .PP |
|
|
3752 | There is no supported compilation method available on windows except |
|
|
3753 | embedding it into other applications. |
|
|
3754 | .PP |
|
|
3755 | Not a libev limitation but worth mentioning: windows apparently doesn't |
|
|
3756 | accept large writes: instead of resulting in a partial write, windows will |
|
|
3757 | either accept everything or return \f(CW\*(C`ENOBUFS\*(C'\fR if the buffer is too large, |
|
|
3758 | so make sure you only write small amounts into your sockets (less than a |
|
|
3759 | megabyte seems safe, but this apparently depends on the amount of memory |
|
|
3760 | available). |
|
|
3761 | .PP |
|
|
3762 | Due to the many, low, and arbitrary limits on the win32 platform and |
|
|
3763 | the abysmal performance of winsockets, using a large number of sockets |
|
|
3764 | is not recommended (and not reasonable). If your program needs to use |
|
|
3765 | more than a hundred or so sockets, then likely it needs to use a totally |
|
|
3766 | different implementation for windows, as libev offers the \s-1POSIX\s0 readiness |
|
|
3767 | notification model, which cannot be implemented efficiently on windows |
|
|
3768 | (Microsoft monopoly games). |
|
|
3769 | .PP |
|
|
3770 | A typical way to use libev under windows is to embed it (see the embedding |
|
|
3771 | section for details) and use the following \fIevwrap.h\fR header file instead |
|
|
3772 | of \fIev.h\fR: |
|
|
3773 | .PP |
|
|
3774 | .Vb 2 |
|
|
3775 | \& #define EV_STANDALONE /* keeps ev from requiring config.h */ |
|
|
3776 | \& #define EV_SELECT_IS_WINSOCKET 1 /* configure libev for windows select */ |
|
|
3777 | \& |
|
|
3778 | \& #include "ev.h" |
|
|
3779 | .Ve |
|
|
3780 | .PP |
|
|
3781 | And compile the following \fIevwrap.c\fR file into your project (make sure |
|
|
3782 | you do \fInot\fR compile the \fIev.c\fR or any other embedded source files!): |
|
|
3783 | .PP |
|
|
3784 | .Vb 2 |
|
|
3785 | \& #include "evwrap.h" |
|
|
3786 | \& #include "ev.c" |
|
|
3787 | .Ve |
|
|
3788 | .IP "The winsocket select function" 4 |
|
|
3789 | .IX Item "The winsocket select function" |
|
|
3790 | The winsocket \f(CW\*(C`select\*(C'\fR function doesn't follow \s-1POSIX\s0 in that it |
|
|
3791 | requires socket \fIhandles\fR and not socket \fIfile descriptors\fR (it is |
|
|
3792 | also extremely buggy). This makes select very inefficient, and also |
|
|
3793 | requires a mapping from file descriptors to socket handles (the Microsoft |
|
|
3794 | C runtime provides the function \f(CW\*(C`_open_osfhandle\*(C'\fR for this). See the |
|
|
3795 | discussion of the \f(CW\*(C`EV_SELECT_USE_FD_SET\*(C'\fR, \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR and |
|
|
3796 | \&\f(CW\*(C`EV_FD_TO_WIN32_HANDLE\*(C'\fR preprocessor symbols for more info. |
|
|
3797 | .Sp |
|
|
3798 | The configuration for a \*(L"naked\*(R" win32 using the Microsoft runtime |
|
|
3799 | libraries and raw winsocket select is: |
|
|
3800 | .Sp |
|
|
3801 | .Vb 2 |
|
|
3802 | \& #define EV_USE_SELECT 1 |
|
|
3803 | \& #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
|
|
3804 | .Ve |
|
|
3805 | .Sp |
|
|
3806 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
|
|
3807 | complexity in the O(nA\*^X) range when using win32. |
|
|
3808 | .IP "Limited number of file descriptors" 4 |
|
|
3809 | .IX Item "Limited number of file descriptors" |
|
|
3810 | Windows has numerous arbitrary (and low) limits on things. |
|
|
3811 | .Sp |
|
|
3812 | Early versions of winsocket's select only supported waiting for a maximum |
|
|
3813 | of \f(CW64\fR handles (probably owning to the fact that all windows kernels |
|
|
3814 | can only wait for \f(CW64\fR things at the same time internally; Microsoft |
|
|
3815 | recommends spawning a chain of threads and wait for 63 handles and the |
|
|
3816 | previous thread in each. Great). |
|
|
3817 | .Sp |
|
|
3818 | Newer versions support more handles, but you need to define \f(CW\*(C`FD_SETSIZE\*(C'\fR |
|
|
3819 | to some high number (e.g. \f(CW2048\fR) before compiling the winsocket select |
|
|
3820 | call (which might be in libev or elsewhere, for example, perl does its own |
|
|
3821 | select emulation on windows). |
|
|
3822 | .Sp |
|
|
3823 | Another limit is the number of file descriptors in the Microsoft runtime |
|
|
3824 | libraries, which by default is \f(CW64\fR (there must be a hidden \fI64\fR fetish |
|
|
3825 | or something like this inside Microsoft). You can increase this by calling |
|
|
3826 | \&\f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR (another |
|
|
3827 | arbitrary limit), but is broken in many versions of the Microsoft runtime |
|
|
3828 | libraries. |
|
|
3829 | .Sp |
|
|
3830 | This might get you to about \f(CW512\fR or \f(CW2048\fR sockets (depending on |
|
|
3831 | windows version and/or the phase of the moon). To get more, you need to |
|
|
3832 | wrap all I/O functions and provide your own fd management, but the cost of |
|
|
3833 | calling select (O(nA\*^X)) will likely make this unworkable. |
|
|
3834 | .Sh "\s-1PORTABILITY\s0 \s-1REQUIREMENTS\s0" |
|
|
3835 | .IX Subsection "PORTABILITY REQUIREMENTS" |
|
|
3836 | In addition to a working ISO-C implementation and of course the |
|
|
3837 | backend-specific APIs, libev relies on a few additional extensions: |
|
|
3838 | .ie n .IP """void (*)(ev_watcher_type *, int revents)""\fR must have compatible calling conventions regardless of \f(CW""ev_watcher_type *""." 4 |
|
|
3839 | .el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4 |
|
|
3840 | .IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *." |
|
|
3841 | Libev assumes not only that all watcher pointers have the same internal |
|
|
3842 | structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO\s0 C for example), but it also |
|
|
3843 | assumes that the same (machine) code can be used to call any watcher |
|
|
3844 | callback: The watcher callbacks have different type signatures, but libev |
|
|
3845 | calls them using an \f(CW\*(C`ev_watcher *\*(C'\fR internally. |
|
|
3846 | .ie n .IP """sig_atomic_t volatile"" must be thread-atomic as well" 4 |
|
|
3847 | .el .IP "\f(CWsig_atomic_t volatile\fR must be thread-atomic as well" 4 |
|
|
3848 | .IX Item "sig_atomic_t volatile must be thread-atomic as well" |
|
|
3849 | The type \f(CW\*(C`sig_atomic_t volatile\*(C'\fR (or whatever is defined as |
|
|
3850 | \&\f(CW\*(C`EV_ATOMIC_T\*(C'\fR) must be atomic with respect to accesses from different |
|
|
3851 | threads. This is not part of the specification for \f(CW\*(C`sig_atomic_t\*(C'\fR, but is |
|
|
3852 | believed to be sufficiently portable. |
|
|
3853 | .ie n .IP """sigprocmask"" must work in a threaded environment" 4 |
|
|
3854 | .el .IP "\f(CWsigprocmask\fR must work in a threaded environment" 4 |
|
|
3855 | .IX Item "sigprocmask must work in a threaded environment" |
|
|
3856 | Libev uses \f(CW\*(C`sigprocmask\*(C'\fR to temporarily block signals. This is not |
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3857 | allowed in a threaded program (\f(CW\*(C`pthread_sigmask\*(C'\fR has to be used). Typical |
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3858 | pthread implementations will either allow \f(CW\*(C`sigprocmask\*(C'\fR in the \*(L"main |
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3859 | thread\*(R" or will block signals process-wide, both behaviours would |
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3860 | be compatible with libev. Interaction between \f(CW\*(C`sigprocmask\*(C'\fR and |
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3861 | \&\f(CW\*(C`pthread_sigmask\*(C'\fR could complicate things, however. |
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3862 | .Sp |
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3863 | The most portable way to handle signals is to block signals in all threads |
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3864 | except the initial one, and run the default loop in the initial thread as |
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3865 | well. |
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3866 | .ie n .IP """long"" must be large enough for common memory allocation sizes" 4 |
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3867 | .el .IP "\f(CWlong\fR must be large enough for common memory allocation sizes" 4 |
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3868 | .IX Item "long must be large enough for common memory allocation sizes" |
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3869 | To improve portability and simplify its \s-1API\s0, libev uses \f(CW\*(C`long\*(C'\fR internally |
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3870 | instead of \f(CW\*(C`size_t\*(C'\fR when allocating its data structures. On non-POSIX |
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3871 | systems (Microsoft...) this might be unexpectedly low, but is still at |
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3872 | least 31 bits everywhere, which is enough for hundreds of millions of |
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3873 | watchers. |
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3874 | .ie n .IP """double"" must hold a time value in seconds with enough accuracy" 4 |
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3875 | .el .IP "\f(CWdouble\fR must hold a time value in seconds with enough accuracy" 4 |
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3876 | .IX Item "double must hold a time value in seconds with enough accuracy" |
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3877 | The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to |
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3878 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
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3879 | enough for at least into the year 4000. This requirement is fulfilled by |
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3880 | implementations implementing \s-1IEEE\s0 754 (basically all existing ones). |
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3881 | .PP |
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3882 | If you know of other additional requirements drop me a note. |
2243 | .SH "COMPLEXITIES" |
3883 | .SH "ALGORITHMIC COMPLEXITIES" |
2244 | .IX Header "COMPLEXITIES" |
3884 | .IX Header "ALGORITHMIC COMPLEXITIES" |
2245 | In this section the complexities of (many of) the algorithms used inside |
3885 | In this section the complexities of (many of) the algorithms used inside |
2246 | libev will be explained. For complexity discussions about backends see the |
3886 | libev will be documented. For complexity discussions about backends see |
2247 | documentation for \f(CW\*(C`ev_default_init\*(C'\fR. |
3887 | the documentation for \f(CW\*(C`ev_default_init\*(C'\fR. |
2248 | .RS 4 |
3888 | .PP |
|
|
3889 | All of the following are about amortised time: If an array needs to be |
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|
3890 | extended, libev needs to realloc and move the whole array, but this |
|
|
3891 | happens asymptotically rarer with higher number of elements, so O(1) might |
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|
3892 | mean that libev does a lengthy realloc operation in rare cases, but on |
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|
3893 | average it is much faster and asymptotically approaches constant time. |
2249 | .IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4 |
3894 | .IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4 |
2250 | .IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" |
3895 | .IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" |
|
|
3896 | This means that, when you have a watcher that triggers in one hour and |
|
|
3897 | there are 100 watchers that would trigger before that, then inserting will |
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|
3898 | have to skip roughly seven (\f(CW\*(C`ld 100\*(C'\fR) of these watchers. |
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|
3899 | .IP "Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers)" 4 |
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3900 | .IX Item "Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers)" |
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|
3901 | That means that changing a timer costs less than removing/adding them, |
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|
3902 | as only the relative motion in the event queue has to be paid for. |
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|
3903 | .IP "Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1)" 4 |
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3904 | .IX Item "Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1)" |
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|
3905 | These just add the watcher into an array or at the head of a list. |
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|
3906 | .IP "Stopping check/prepare/idle/fork/async watchers: O(1)" 4 |
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3907 | .IX Item "Stopping check/prepare/idle/fork/async watchers: O(1)" |
2251 | .PD 0 |
3908 | .PD 0 |
2252 | .IP "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 4 |
|
|
2253 | .IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" |
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|
2254 | .IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4 |
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2255 | .IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)" |
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|
2256 | .IP "Stopping check/prepare/idle watchers: O(1)" 4 |
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2257 | .IX Item "Stopping check/prepare/idle watchers: O(1)" |
|
|
2258 | .IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))" 4 |
3909 | .IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4 |
2259 | .IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))" |
3910 | .IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))" |
|
|
3911 | .PD |
|
|
3912 | These watchers are stored in lists, so they need to be walked to find the |
|
|
3913 | correct watcher to remove. The lists are usually short (you don't usually |
|
|
3914 | have many watchers waiting for the same fd or signal: one is typical, two |
|
|
3915 | is rare). |
2260 | .IP "Finding the next timer per loop iteration: O(1)" 4 |
3916 | .IP "Finding the next timer in each loop iteration: O(1)" 4 |
2261 | .IX Item "Finding the next timer per loop iteration: O(1)" |
3917 | .IX Item "Finding the next timer in each loop iteration: O(1)" |
|
|
3918 | By virtue of using a binary or 4\-heap, the next timer is always found at a |
|
|
3919 | fixed position in the storage array. |
2262 | .IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4 |
3920 | .IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4 |
2263 | .IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" |
3921 | .IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" |
2264 | .IP "Activating one watcher: O(1)" 4 |
3922 | A change means an I/O watcher gets started or stopped, which requires |
2265 | .IX Item "Activating one watcher: O(1)" |
3923 | libev to recalculate its status (and possibly tell the kernel, depending |
2266 | .RE |
3924 | on backend and whether \f(CW\*(C`ev_io_set\*(C'\fR was used). |
2267 | .RS 4 |
3925 | .IP "Activating one watcher (putting it into the pending state): O(1)" 4 |
|
|
3926 | .IX Item "Activating one watcher (putting it into the pending state): O(1)" |
|
|
3927 | .PD 0 |
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|
3928 | .IP "Priority handling: O(number_of_priorities)" 4 |
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|
3929 | .IX Item "Priority handling: O(number_of_priorities)" |
2268 | .PD |
3930 | .PD |
|
|
3931 | Priorities are implemented by allocating some space for each |
|
|
3932 | priority. When doing priority-based operations, libev usually has to |
|
|
3933 | linearly search all the priorities, but starting/stopping and activating |
|
|
3934 | watchers becomes O(1) with respect to priority handling. |
|
|
3935 | .IP "Sending an ev_async: O(1)" 4 |
|
|
3936 | .IX Item "Sending an ev_async: O(1)" |
|
|
3937 | .PD 0 |
|
|
3938 | .IP "Processing ev_async_send: O(number_of_async_watchers)" 4 |
|
|
3939 | .IX Item "Processing ev_async_send: O(number_of_async_watchers)" |
|
|
3940 | .IP "Processing signals: O(max_signal_number)" 4 |
|
|
3941 | .IX Item "Processing signals: O(max_signal_number)" |
|
|
3942 | .PD |
|
|
3943 | Sending involves a system call \fIiff\fR there were no other \f(CW\*(C`ev_async_send\*(C'\fR |
|
|
3944 | calls in the current loop iteration. Checking for async and signal events |
|
|
3945 | involves iterating over all running async watchers or all signal numbers. |
2269 | .SH "AUTHOR" |
3946 | .SH "AUTHOR" |
2270 | .IX Header "AUTHOR" |
3947 | .IX Header "AUTHOR" |
2271 | Marc Lehmann <libev@schmorp.de>. |
3948 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |