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129 | .\" ======================================================================== |
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133 | .\" |
131 | .IX Title "EV 1" |
134 | .IX Title "EV 1" |
132 | .TH EV 1 "2007-12-21" "perl v5.8.8" "User Contributed Perl Documentation" |
135 | .TH EV 1 "2008-04-02" "perl v5.10.0" "User Contributed Perl Documentation" |
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136 | .\" For nroff, turn off justification. Always turn off hyphenation; it makes |
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137 | .\" way too many mistakes in technical documents. |
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138 | .if n .ad l |
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139 | .nh |
133 | .SH "NAME" |
140 | .SH "NAME" |
134 | libev \- a high performance full\-featured event loop written in C |
141 | libev \- a high performance full\-featured event loop written in C |
135 | .SH "SYNOPSIS" |
142 | .SH "SYNOPSIS" |
136 | .IX Header "SYNOPSIS" |
143 | .IX Header "SYNOPSIS" |
137 | .Vb 1 |
144 | .Vb 1 |
138 | \& #include <ev.h> |
145 | \& #include <ev.h> |
139 | .Ve |
146 | .Ve |
140 | .SH "EXAMPLE PROGRAM" |
147 | .Sh "\s-1EXAMPLE\s0 \s-1PROGRAM\s0" |
141 | .IX Header "EXAMPLE PROGRAM" |
148 | .IX Subsection "EXAMPLE PROGRAM" |
142 | .Vb 1 |
149 | .Vb 2 |
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150 | \& // a single header file is required |
143 | \& #include <ev.h> |
151 | \& #include <ev.h> |
144 | .Ve |
152 | \& |
145 | .PP |
153 | \& // every watcher type has its own typedef\*(Aqd struct |
146 | .Vb 2 |
154 | \& // with the name ev_<type> |
147 | \& ev_io stdin_watcher; |
155 | \& ev_io stdin_watcher; |
148 | \& ev_timer timeout_watcher; |
156 | \& ev_timer timeout_watcher; |
149 | .Ve |
157 | \& |
150 | .PP |
158 | \& // all watcher callbacks have a similar signature |
151 | .Vb 8 |
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152 | \& /* called when data readable on stdin */ |
159 | \& // this callback is called when data is readable on stdin |
153 | \& static void |
160 | \& static void |
154 | \& stdin_cb (EV_P_ struct ev_io *w, int revents) |
161 | \& stdin_cb (EV_P_ struct ev_io *w, int revents) |
155 | \& { |
162 | \& { |
156 | \& /* puts ("stdin ready"); */ |
163 | \& puts ("stdin ready"); |
157 | \& ev_io_stop (EV_A_ w); /* just a syntax example */ |
164 | \& // for one\-shot events, one must manually stop the watcher |
158 | \& ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */ |
165 | \& // with its corresponding stop function. |
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166 | \& ev_io_stop (EV_A_ w); |
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167 | \& |
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168 | \& // this causes all nested ev_loop\*(Aqs to stop iterating |
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169 | \& ev_unloop (EV_A_ EVUNLOOP_ALL); |
159 | \& } |
170 | \& } |
160 | .Ve |
171 | \& |
161 | .PP |
172 | \& // another callback, this time for a time\-out |
162 | .Vb 6 |
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163 | \& static void |
173 | \& static void |
164 | \& timeout_cb (EV_P_ struct ev_timer *w, int revents) |
174 | \& timeout_cb (EV_P_ struct ev_timer *w, int revents) |
165 | \& { |
175 | \& { |
166 | \& /* puts ("timeout"); */ |
176 | \& puts ("timeout"); |
167 | \& ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */ |
177 | \& // this causes the innermost ev_loop to stop iterating |
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178 | \& ev_unloop (EV_A_ EVUNLOOP_ONE); |
168 | \& } |
179 | \& } |
169 | .Ve |
180 | \& |
170 | .PP |
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171 | .Vb 4 |
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172 | \& int |
181 | \& int |
173 | \& main (void) |
182 | \& main (void) |
174 | \& { |
183 | \& { |
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184 | \& // use the default event loop unless you have special needs |
175 | \& struct ev_loop *loop = ev_default_loop (0); |
185 | \& struct ev_loop *loop = ev_default_loop (0); |
176 | .Ve |
186 | \& |
177 | .PP |
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178 | .Vb 3 |
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179 | \& /* initialise an io watcher, then start it */ |
187 | \& // initialise an io watcher, then start it |
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188 | \& // this one will watch for stdin to become readable |
180 | \& ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
189 | \& ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
181 | \& ev_io_start (loop, &stdin_watcher); |
190 | \& ev_io_start (loop, &stdin_watcher); |
182 | .Ve |
191 | \& |
183 | .PP |
192 | \& // initialise a timer watcher, then start it |
184 | .Vb 3 |
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185 | \& /* simple non-repeating 5.5 second timeout */ |
193 | \& // simple non\-repeating 5.5 second timeout |
186 | \& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
194 | \& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
187 | \& ev_timer_start (loop, &timeout_watcher); |
195 | \& ev_timer_start (loop, &timeout_watcher); |
188 | .Ve |
196 | \& |
189 | .PP |
197 | \& // now wait for events to arrive |
190 | .Vb 2 |
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191 | \& /* loop till timeout or data ready */ |
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192 | \& ev_loop (loop, 0); |
198 | \& ev_loop (loop, 0); |
193 | .Ve |
199 | \& |
194 | .PP |
200 | \& // unloop was called, so exit |
195 | .Vb 2 |
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196 | \& return 0; |
201 | \& return 0; |
197 | \& } |
202 | \& } |
198 | .Ve |
203 | .Ve |
199 | .SH "DESCRIPTION" |
204 | .SH "DESCRIPTION" |
200 | .IX Header "DESCRIPTION" |
205 | .IX Header "DESCRIPTION" |
201 | The newest version of this document is also available as a html-formatted |
206 | The newest version of this document is also available as an html-formatted |
202 | web page you might find easier to navigate when reading it for the first |
207 | web page you might find easier to navigate when reading it for the first |
203 | time: <http://cvs.schmorp.de/libev/ev.html>. |
208 | time: <http://cvs.schmorp.de/libev/ev.html>. |
204 | .PP |
209 | .PP |
205 | 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 |
206 | file descriptor being readable or a timeout occurring), and it will manage |
211 | file descriptor being readable or a timeout occurring), and it will manage |
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212 | .PP |
217 | .PP |
213 | You register interest in certain events by registering so-called \fIevent |
218 | You register interest in certain events by registering so-called \fIevent |
214 | 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 |
215 | 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 |
216 | watcher. |
221 | watcher. |
217 | .SH "FEATURES" |
222 | .Sh "\s-1FEATURES\s0" |
218 | .IX Header "FEATURES" |
223 | .IX Subsection "FEATURES" |
219 | Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the Linux-specific \f(CW\*(C`epoll\*(C'\fR, the |
224 | Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the Linux-specific \f(CW\*(C`epoll\*(C'\fR, the |
220 | BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port mechanisms |
225 | BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port mechanisms |
221 | for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR interface |
226 | for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR interface |
222 | (for \f(CW\*(C`ev_stat\*(C'\fR), relative timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers |
227 | (for \f(CW\*(C`ev_stat\*(C'\fR), relative timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers |
223 | with customised rescheduling (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals |
228 | with customised rescheduling (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals |
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228 | (\f(CW\*(C`ev_fork\*(C'\fR). |
233 | (\f(CW\*(C`ev_fork\*(C'\fR). |
229 | .PP |
234 | .PP |
230 | It also is quite fast (see this |
235 | It also is quite fast (see this |
231 | benchmark comparing it to libevent |
236 | benchmark comparing it to libevent |
232 | for example). |
237 | for example). |
233 | .SH "CONVENTIONS" |
238 | .Sh "\s-1CONVENTIONS\s0" |
234 | .IX Header "CONVENTIONS" |
239 | .IX Subsection "CONVENTIONS" |
235 | Libev is very configurable. In this manual the default configuration will |
240 | Libev is very configurable. In this manual the default (and most common) |
236 | be described, which supports multiple event loops. For more info about |
241 | configuration will be described, which supports multiple event loops. For |
237 | various configuration options please have a look at \fB\s-1EMBED\s0\fR section in |
242 | more info about various configuration options please have a look at |
238 | this manual. If libev was configured without support for multiple event |
243 | \&\fB\s-1EMBED\s0\fR section in this manual. If libev was configured without support |
239 | loops, then all functions taking an initial argument of name \f(CW\*(C`loop\*(C'\fR |
244 | for multiple event loops, then all functions taking an initial argument of |
240 | (which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) will not have this argument. |
245 | name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) will not have |
241 | .SH "TIME REPRESENTATION" |
246 | this argument. |
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247 | .Sh "\s-1TIME\s0 \s-1REPRESENTATION\s0" |
242 | .IX Header "TIME REPRESENTATION" |
248 | .IX Subsection "TIME REPRESENTATION" |
243 | Libev represents time as a single floating point number, representing the |
249 | Libev represents time as a single floating point number, representing the |
244 | (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 |
245 | 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 |
246 | 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 |
247 | 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 |
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255 | .IP "ev_tstamp ev_time ()" 4 |
261 | .IP "ev_tstamp ev_time ()" 4 |
256 | .IX Item "ev_tstamp ev_time ()" |
262 | .IX Item "ev_tstamp ev_time ()" |
257 | Returns the current time as libev would use it. Please note that the |
263 | Returns the current time as libev would use it. Please note that the |
258 | \&\f(CW\*(C`ev_now\*(C'\fR function is usually faster and also often returns the timestamp |
264 | \&\f(CW\*(C`ev_now\*(C'\fR function is usually faster and also often returns the timestamp |
259 | you actually want to know. |
265 | you actually want to know. |
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266 | .IP "ev_sleep (ev_tstamp interval)" 4 |
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267 | .IX Item "ev_sleep (ev_tstamp interval)" |
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268 | Sleep for the given interval: The current thread will be blocked until |
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269 | either it is interrupted or the given time interval has passed. Basically |
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270 | this is a subsecond-resolution \f(CW\*(C`sleep ()\*(C'\fR. |
260 | .IP "int ev_version_major ()" 4 |
271 | .IP "int ev_version_major ()" 4 |
261 | .IX Item "int ev_version_major ()" |
272 | .IX Item "int ev_version_major ()" |
262 | .PD 0 |
273 | .PD 0 |
263 | .IP "int ev_version_minor ()" 4 |
274 | .IP "int ev_version_minor ()" 4 |
264 | .IX Item "int ev_version_minor ()" |
275 | .IX Item "int ev_version_minor ()" |
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308 | (assuming you know what you are doing). This is the set of backends that |
319 | (assuming you know what you are doing). This is the set of backends that |
309 | libev will probe for if you specify no backends explicitly. |
320 | libev will probe for if you specify no backends explicitly. |
310 | .IP "unsigned int ev_embeddable_backends ()" 4 |
321 | .IP "unsigned int ev_embeddable_backends ()" 4 |
311 | .IX Item "unsigned int ev_embeddable_backends ()" |
322 | .IX Item "unsigned int ev_embeddable_backends ()" |
312 | Returns the set of backends that are embeddable in other event loops. This |
323 | Returns the set of backends that are embeddable in other event loops. This |
313 | is the theoretical, all\-platform, value. To find which backends |
324 | is the theoretical, all-platform, value. To find which backends |
314 | might be supported on the current system, you would need to look at |
325 | might be supported on the current system, you would need to look at |
315 | \&\f(CW\*(C`ev_embeddable_backends () & ev_supported_backends ()\*(C'\fR, likewise for |
326 | \&\f(CW\*(C`ev_embeddable_backends () & ev_supported_backends ()\*(C'\fR, likewise for |
316 | recommended ones. |
327 | recommended ones. |
317 | .Sp |
328 | .Sp |
318 | See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
329 | See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
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337 | \& persistent_realloc (void *ptr, size_t size) |
348 | \& persistent_realloc (void *ptr, size_t size) |
338 | \& { |
349 | \& { |
339 | \& for (;;) |
350 | \& for (;;) |
340 | \& { |
351 | \& { |
341 | \& void *newptr = realloc (ptr, size); |
352 | \& void *newptr = realloc (ptr, size); |
342 | .Ve |
353 | \& |
343 | .Sp |
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344 | .Vb 2 |
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345 | \& if (newptr) |
354 | \& if (newptr) |
346 | \& return newptr; |
355 | \& return newptr; |
347 | .Ve |
356 | \& |
348 | .Sp |
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349 | .Vb 3 |
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350 | \& sleep (60); |
357 | \& sleep (60); |
351 | \& } |
358 | \& } |
352 | \& } |
359 | \& } |
353 | .Ve |
360 | \& |
354 | .Sp |
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355 | .Vb 2 |
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356 | \& ... |
361 | \& ... |
357 | \& ev_set_allocator (persistent_realloc); |
362 | \& ev_set_allocator (persistent_realloc); |
358 | .Ve |
363 | .Ve |
359 | .IP "ev_set_syserr_cb (void (*cb)(const char *msg));" 4 |
364 | .IP "ev_set_syserr_cb (void (*cb)(const char *msg));" 4 |
360 | .IX Item "ev_set_syserr_cb (void (*cb)(const char *msg));" |
365 | .IX Item "ev_set_syserr_cb (void (*cb)(const char *msg));" |
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373 | \& fatal_error (const char *msg) |
378 | \& fatal_error (const char *msg) |
374 | \& { |
379 | \& { |
375 | \& perror (msg); |
380 | \& perror (msg); |
376 | \& abort (); |
381 | \& abort (); |
377 | \& } |
382 | \& } |
378 | .Ve |
383 | \& |
379 | .Sp |
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380 | .Vb 2 |
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381 | \& ... |
384 | \& ... |
382 | \& ev_set_syserr_cb (fatal_error); |
385 | \& ev_set_syserr_cb (fatal_error); |
383 | .Ve |
386 | .Ve |
384 | .SH "FUNCTIONS CONTROLLING THE EVENT LOOP" |
387 | .SH "FUNCTIONS CONTROLLING THE EVENT LOOP" |
385 | .IX Header "FUNCTIONS CONTROLLING THE EVENT LOOP" |
388 | .IX Header "FUNCTIONS CONTROLLING THE EVENT LOOP" |
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400 | false. If it already was initialised it simply returns it (and ignores the |
403 | false. If it already was initialised it simply returns it (and ignores the |
401 | flags. If that is troubling you, check \f(CW\*(C`ev_backend ()\*(C'\fR afterwards). |
404 | flags. If that is troubling you, check \f(CW\*(C`ev_backend ()\*(C'\fR afterwards). |
402 | .Sp |
405 | .Sp |
403 | If you don't know what event loop to use, use the one returned from this |
406 | If you don't know what event loop to use, use the one returned from this |
404 | function. |
407 | function. |
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408 | .Sp |
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409 | Note that this function is \fInot\fR thread-safe, so if you want to use it |
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410 | from multiple threads, you have to lock (note also that this is unlikely, |
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411 | as loops cannot bes hared easily between threads anyway). |
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412 | .Sp |
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413 | The default loop is the only loop that can handle \f(CW\*(C`ev_signal\*(C'\fR and |
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414 | \&\f(CW\*(C`ev_child\*(C'\fR watchers, and to do this, it always registers a handler |
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415 | for \f(CW\*(C`SIGCHLD\*(C'\fR. If this is a problem for your app you can either |
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416 | create a dynamic loop with \f(CW\*(C`ev_loop_new\*(C'\fR that doesn't do that, or you |
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417 | can simply overwrite the \f(CW\*(C`SIGCHLD\*(C'\fR signal handler \fIafter\fR calling |
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418 | \&\f(CW\*(C`ev_default_init\*(C'\fR. |
405 | .Sp |
419 | .Sp |
406 | The flags argument can be used to specify special behaviour or specific |
420 | The flags argument can be used to specify special behaviour or specific |
407 | backends to use, and is usually specified as \f(CW0\fR (or \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). |
421 | backends to use, and is usually specified as \f(CW0\fR (or \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). |
408 | .Sp |
422 | .Sp |
409 | The following flags are supported: |
423 | The following flags are supported: |
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430 | enabling this flag. |
444 | enabling this flag. |
431 | .Sp |
445 | .Sp |
432 | This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop, |
446 | This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop, |
433 | and thus this might slow down your event loop if you do a lot of loop |
447 | and thus this might slow down your event loop if you do a lot of loop |
434 | iterations and little real work, but is usually not noticeable (on my |
448 | iterations and little real work, but is usually not noticeable (on my |
435 | Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence |
449 | GNU/Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence |
436 | without a syscall and thus \fIvery\fR fast, but my Linux system also has |
450 | without a syscall and thus \fIvery\fR fast, but my GNU/Linux system also has |
437 | \&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster). |
451 | \&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster). |
438 | .Sp |
452 | .Sp |
439 | The big advantage of this flag is that you can forget about fork (and |
453 | The big advantage of this flag is that you can forget about fork (and |
440 | forget about forgetting to tell libev about forking) when you use this |
454 | forget about forgetting to tell libev about forking) when you use this |
441 | flag. |
455 | flag. |
… | |
… | |
446 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
460 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
447 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
461 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
448 | This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
462 | This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
449 | libev tries to roll its own fd_set with no limits on the number of fds, |
463 | libev tries to roll its own fd_set with no limits on the number of fds, |
450 | but if that fails, expect a fairly low limit on the number of fds when |
464 | but if that fails, expect a fairly low limit on the number of fds when |
451 | using this backend. It doesn't scale too well (O(highest_fd)), but its usually |
465 | using this backend. It doesn't scale too well (O(highest_fd)), but its |
452 | the fastest backend for a low number of fds. |
466 | usually the fastest backend for a low number of (low-numbered :) fds. |
|
|
467 | .Sp |
|
|
468 | To get good performance out of this backend you need a high amount of |
|
|
469 | parallelity (most of the file descriptors should be busy). If you are |
|
|
470 | writing a server, you should \f(CW\*(C`accept ()\*(C'\fR in a loop to accept as many |
|
|
471 | connections as possible during one iteration. You might also want to have |
|
|
472 | a look at \f(CW\*(C`ev_set_io_collect_interval ()\*(C'\fR to increase the amount of |
|
|
473 | readyness notifications you get per iteration. |
453 | .ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4 |
474 | .ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4 |
454 | .el .IP "\f(CWEVBACKEND_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4 |
475 | .el .IP "\f(CWEVBACKEND_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4 |
455 | .IX Item "EVBACKEND_POLL (value 2, poll backend, available everywhere except on windows)" |
476 | .IX Item "EVBACKEND_POLL (value 2, poll backend, available everywhere except on windows)" |
456 | And this is your standard \fIpoll\fR\|(2) backend. It's more complicated than |
477 | And this is your standard \fIpoll\fR\|(2) backend. It's more complicated |
457 | select, but handles sparse fds better and has no artificial limit on the |
478 | than select, but handles sparse fds better and has no artificial |
458 | number of fds you can use (except it will slow down considerably with a |
479 | limit on the number of fds you can use (except it will slow down |
459 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds). |
480 | considerably with a lot of inactive fds). It scales similarly to select, |
|
|
481 | i.e. O(total_fds). See the entry for \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR, above, for |
|
|
482 | performance tips. |
460 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
483 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
461 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
484 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
462 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
485 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
463 | For few fds, this backend is a bit little slower than poll and select, |
486 | For few fds, this backend is a bit little slower than poll and select, |
464 | but it scales phenomenally better. While poll and select usually scale |
487 | but it scales phenomenally better. While poll and select usually scale |
465 | like O(total_fds) where n is the total number of fds (or the highest fd), |
488 | like O(total_fds) where n is the total number of fds (or the highest fd), |
466 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
489 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
467 | of shortcomings, such as silently dropping events in some hard-to-detect |
490 | of shortcomings, such as silently dropping events in some hard-to-detect |
468 | cases and rewuiring a syscall per fd change, no fork support and bad |
491 | cases and rewiring a syscall per fd change, no fork support and bad |
469 | support for dup: |
492 | support for dup. |
470 | .Sp |
493 | .Sp |
471 | While stopping, setting and starting an I/O watcher in the same iteration |
494 | While stopping, setting and starting an I/O watcher in the same iteration |
472 | will result in some caching, there is still a syscall per such incident |
495 | will result in some caching, there is still a syscall per such incident |
473 | (because the fd could point to a different file description now), so its |
496 | (because the fd could point to a different file description now), so its |
474 | best to avoid that. Also, \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors might not work |
497 | best to avoid that. Also, \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors might not work |
475 | very well if you register events for both fds. |
498 | very well if you register events for both fds. |
476 | .Sp |
499 | .Sp |
477 | Please note that epoll sometimes generates spurious notifications, so you |
500 | Please note that epoll sometimes generates spurious notifications, so you |
478 | need to use non-blocking I/O or other means to avoid blocking when no data |
501 | need to use non-blocking I/O or other means to avoid blocking when no data |
479 | (or space) is available. |
502 | (or space) is available. |
|
|
503 | .Sp |
|
|
504 | Best performance from this backend is achieved by not unregistering all |
|
|
505 | watchers for a file descriptor until it has been closed, if possible, i.e. |
|
|
506 | keep at least one watcher active per fd at all times. |
|
|
507 | .Sp |
|
|
508 | While nominally embeddeble in other event loops, this feature is broken in |
|
|
509 | all kernel versions tested so far. |
480 | .ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 |
510 | .ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 |
481 | .el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 |
511 | .el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 |
482 | .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" |
512 | .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" |
483 | Kqueue deserves special mention, as at the time of this writing, it |
513 | Kqueue deserves special mention, as at the time of this writing, it |
484 | was broken on \fIall\fR BSDs (usually it doesn't work with anything but |
514 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
485 | sockets and pipes, except on Darwin, where of course it's completely |
515 | with anything but sockets and pipes, except on Darwin, where of course |
486 | useless. On NetBSD, it seems to work for all the \s-1FD\s0 types I tested, so it |
|
|
487 | is used by default there). For this reason it's not being \*(L"autodetected\*(R" |
516 | it's completely useless). For this reason it's not being \*(L"autodetected\*(R" |
488 | unless you explicitly specify it explicitly in the flags (i.e. using |
517 | unless you explicitly specify it explicitly in the flags (i.e. using |
489 | \&\f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR) or libev was compiled on a known-to-be-good (\-enough) |
518 | \&\f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR) or libev was compiled on a known-to-be-good (\-enough) |
490 | system like NetBSD. |
519 | system like NetBSD. |
491 | .Sp |
520 | .Sp |
|
|
521 | You still can embed kqueue into a normal poll or select backend and use it |
|
|
522 | only for sockets (after having made sure that sockets work with kqueue on |
|
|
523 | the target platform). See \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
|
|
524 | .Sp |
492 | It scales in the same way as the epoll backend, but the interface to the |
525 | It scales in the same way as the epoll backend, but the interface to the |
493 | kernel is more efficient (which says nothing about its actual speed, |
526 | kernel is more efficient (which says nothing about its actual speed, of |
494 | of course). While stopping, setting and starting an I/O watcher does |
527 | course). While stopping, setting and starting an I/O watcher does never |
495 | never cause an extra syscall as with epoll, it still adds up to two event |
528 | cause an extra syscall as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to |
496 | changes per incident, support for \f(CW\*(C`fork ()\*(C'\fR is very bad and it drops fds |
529 | two event changes per incident, support for \f(CW\*(C`fork ()\*(C'\fR is very bad and it |
497 | silently in similarly hard-to-detetc cases. |
530 | drops fds silently in similarly hard-to-detect cases. |
|
|
531 | .Sp |
|
|
532 | This backend usually performs well under most conditions. |
|
|
533 | .Sp |
|
|
534 | While nominally embeddable in other event loops, this doesn't work |
|
|
535 | everywhere, so you might need to test for this. And since it is broken |
|
|
536 | almost everywhere, you should only use it when you have a lot of sockets |
|
|
537 | (for which it usually works), by embedding it into another event loop |
|
|
538 | (e.g. \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR) and using it only for |
|
|
539 | sockets. |
498 | .ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 |
540 | .ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 |
499 | .el .IP "\f(CWEVBACKEND_DEVPOLL\fR (value 16, Solaris 8)" 4 |
541 | .el .IP "\f(CWEVBACKEND_DEVPOLL\fR (value 16, Solaris 8)" 4 |
500 | .IX Item "EVBACKEND_DEVPOLL (value 16, Solaris 8)" |
542 | .IX Item "EVBACKEND_DEVPOLL (value 16, Solaris 8)" |
501 | This is not implemented yet (and might never be). |
543 | This is not implemented yet (and might never be, unless you send me an |
|
|
544 | implementation). According to reports, \f(CW\*(C`/dev/poll\*(C'\fR only supports sockets |
|
|
545 | and is not embeddable, which would limit the usefulness of this backend |
|
|
546 | immensely. |
502 | .ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 |
547 | .ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 |
503 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
548 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
504 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
549 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
505 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
550 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
506 | it's really slow, but it still scales very well (O(active_fds)). |
551 | it's really slow, but it still scales very well (O(active_fds)). |
507 | .Sp |
552 | .Sp |
508 | Please note that solaris event ports can deliver a lot of spurious |
553 | Please note that solaris event ports can deliver a lot of spurious |
509 | notifications, so you need to use non-blocking I/O or other means to avoid |
554 | notifications, so you need to use non-blocking I/O or other means to avoid |
510 | blocking when no data (or space) is available. |
555 | blocking when no data (or space) is available. |
|
|
556 | .Sp |
|
|
557 | While this backend scales well, it requires one system call per active |
|
|
558 | file descriptor per loop iteration. For small and medium numbers of file |
|
|
559 | descriptors a \*(L"slow\*(R" \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR backend |
|
|
560 | might perform better. |
|
|
561 | .Sp |
|
|
562 | On the positive side, ignoring the spurious readyness notifications, this |
|
|
563 | backend actually performed to specification in all tests and is fully |
|
|
564 | embeddable, which is a rare feat among the OS-specific backends. |
511 | .ie n .IP """EVBACKEND_ALL""" 4 |
565 | .ie n .IP """EVBACKEND_ALL""" 4 |
512 | .el .IP "\f(CWEVBACKEND_ALL\fR" 4 |
566 | .el .IP "\f(CWEVBACKEND_ALL\fR" 4 |
513 | .IX Item "EVBACKEND_ALL" |
567 | .IX Item "EVBACKEND_ALL" |
514 | Try all backends (even potentially broken ones that wouldn't be tried |
568 | Try all backends (even potentially broken ones that wouldn't be tried |
515 | with \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). Since this is a mask, you can do stuff such as |
569 | with \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). Since this is a mask, you can do stuff such as |
516 | \&\f(CW\*(C`EVBACKEND_ALL & ~EVBACKEND_KQUEUE\*(C'\fR. |
570 | \&\f(CW\*(C`EVBACKEND_ALL & ~EVBACKEND_KQUEUE\*(C'\fR. |
|
|
571 | .Sp |
|
|
572 | It is definitely not recommended to use this flag. |
517 | .RE |
573 | .RE |
518 | .RS 4 |
574 | .RS 4 |
519 | .Sp |
575 | .Sp |
520 | If one or more of these are ored into the flags value, then only these |
576 | If one or more of these are ored into the flags value, then only these |
521 | backends will be tried (in the reverse order as given here). If none are |
577 | backends will be tried (in the reverse order as listed here). If none are |
522 | specified, most compiled-in backend will be tried, usually in reverse |
578 | specified, all backends in \f(CW\*(C`ev_recommended_backends ()\*(C'\fR will be tried. |
523 | order of their flag values :) |
|
|
524 | .Sp |
579 | .Sp |
525 | The most typical usage is like this: |
580 | The most typical usage is like this: |
526 | .Sp |
581 | .Sp |
527 | .Vb 2 |
582 | .Vb 2 |
528 | \& if (!ev_default_loop (0)) |
583 | \& if (!ev_default_loop (0)) |
… | |
… | |
548 | .IX Item "struct ev_loop *ev_loop_new (unsigned int flags)" |
603 | .IX Item "struct ev_loop *ev_loop_new (unsigned int flags)" |
549 | Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is |
604 | Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is |
550 | always distinct from the default loop. Unlike the default loop, it cannot |
605 | always distinct from the default loop. Unlike the default loop, it cannot |
551 | handle signal and child watchers, and attempts to do so will be greeted by |
606 | handle signal and child watchers, and attempts to do so will be greeted by |
552 | undefined behaviour (or a failed assertion if assertions are enabled). |
607 | undefined behaviour (or a failed assertion if assertions are enabled). |
|
|
608 | .Sp |
|
|
609 | Note that this function \fIis\fR thread-safe, and the recommended way to use |
|
|
610 | libev with threads is indeed to create one loop per thread, and using the |
|
|
611 | default loop in the \*(L"main\*(R" or \*(L"initial\*(R" thread. |
553 | .Sp |
612 | .Sp |
554 | Example: Try to create a event loop that uses epoll and nothing else. |
613 | Example: Try to create a event loop that uses epoll and nothing else. |
555 | .Sp |
614 | .Sp |
556 | .Vb 3 |
615 | .Vb 3 |
557 | \& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
616 | \& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
… | |
… | |
580 | .IX Item "ev_loop_destroy (loop)" |
639 | .IX Item "ev_loop_destroy (loop)" |
581 | Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an |
640 | Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an |
582 | earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR. |
641 | earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR. |
583 | .IP "ev_default_fork ()" 4 |
642 | .IP "ev_default_fork ()" 4 |
584 | .IX Item "ev_default_fork ()" |
643 | .IX Item "ev_default_fork ()" |
|
|
644 | This function sets a flag that causes subsequent \f(CW\*(C`ev_loop\*(C'\fR iterations |
585 | This function reinitialises the kernel state for backends that have |
645 | to reinitialise the kernel state for backends that have one. Despite the |
586 | one. Despite the name, you can call it anytime, but it makes most sense |
646 | name, you can call it anytime, but it makes most sense after forking, in |
587 | after forking, in either the parent or child process (or both, but that |
647 | the child process (or both child and parent, but that again makes little |
588 | again makes little sense). |
648 | sense). You \fImust\fR call it in the child before using any of the libev |
|
|
649 | functions, and it will only take effect at the next \f(CW\*(C`ev_loop\*(C'\fR iteration. |
589 | .Sp |
650 | .Sp |
590 | You \fImust\fR call this function in the child process after forking if and |
651 | On the other hand, you only need to call this function in the child |
591 | only if you want to use the event library in both processes. If you just |
652 | process if and only if you want to use the event library in the child. If |
592 | fork+exec, you don't have to call it. |
653 | you just fork+exec, you don't have to call it at all. |
593 | .Sp |
654 | .Sp |
594 | The function itself is quite fast and it's usually not a problem to call |
655 | The function itself is quite fast and it's usually not a problem to call |
595 | it just in case after a fork. To make this easy, the function will fit in |
656 | it just in case after a fork. To make this easy, the function will fit in |
596 | quite nicely into a call to \f(CW\*(C`pthread_atfork\*(C'\fR: |
657 | quite nicely into a call to \f(CW\*(C`pthread_atfork\*(C'\fR: |
597 | .Sp |
658 | .Sp |
598 | .Vb 1 |
659 | .Vb 1 |
599 | \& pthread_atfork (0, 0, ev_default_fork); |
660 | \& pthread_atfork (0, 0, ev_default_fork); |
600 | .Ve |
661 | .Ve |
601 | .Sp |
|
|
602 | At the moment, \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and \f(CW\*(C`EVBACKEND_POLL\*(C'\fR are safe to use |
|
|
603 | without calling this function, so if you force one of those backends you |
|
|
604 | do not need to care. |
|
|
605 | .IP "ev_loop_fork (loop)" 4 |
662 | .IP "ev_loop_fork (loop)" 4 |
606 | .IX Item "ev_loop_fork (loop)" |
663 | .IX Item "ev_loop_fork (loop)" |
607 | Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by |
664 | Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by |
608 | \&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop |
665 | \&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop |
609 | after fork, and how you do this is entirely your own problem. |
666 | after fork, and how you do this is entirely your own problem. |
|
|
667 | .IP "int ev_is_default_loop (loop)" 4 |
|
|
668 | .IX Item "int ev_is_default_loop (loop)" |
|
|
669 | Returns true when the given loop actually is the default loop, false otherwise. |
610 | .IP "unsigned int ev_loop_count (loop)" 4 |
670 | .IP "unsigned int ev_loop_count (loop)" 4 |
611 | .IX Item "unsigned int ev_loop_count (loop)" |
671 | .IX Item "unsigned int ev_loop_count (loop)" |
612 | Returns the count of loop iterations for the loop, which is identical to |
672 | Returns the count of loop iterations for the loop, which is identical to |
613 | the number of times libev did poll for new events. It starts at \f(CW0\fR and |
673 | the number of times libev did poll for new events. It starts at \f(CW0\fR and |
614 | happily wraps around with enough iterations. |
674 | happily wraps around with enough iterations. |
… | |
… | |
654 | libev watchers. However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is |
714 | libev watchers. However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is |
655 | usually a better approach for this kind of thing. |
715 | usually a better approach for this kind of thing. |
656 | .Sp |
716 | .Sp |
657 | Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does: |
717 | Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does: |
658 | .Sp |
718 | .Sp |
659 | .Vb 19 |
719 | .Vb 10 |
660 | \& - Before the first iteration, call any pending watchers. |
720 | \& \- Before the first iteration, call any pending watchers. |
661 | \& * If there are no active watchers (reference count is zero), return. |
721 | \& * If EVFLAG_FORKCHECK was used, check for a fork. |
662 | \& - Queue all prepare watchers and then call all outstanding watchers. |
722 | \& \- If a fork was detected, queue and call all fork watchers. |
|
|
723 | \& \- Queue and call all prepare watchers. |
663 | \& - If we have been forked, recreate the kernel state. |
724 | \& \- If we have been forked, recreate the kernel state. |
664 | \& - Update the kernel state with all outstanding changes. |
725 | \& \- Update the kernel state with all outstanding changes. |
665 | \& - Update the "event loop time". |
726 | \& \- Update the "event loop time". |
666 | \& - Calculate for how long to block. |
727 | \& \- Calculate for how long to sleep or block, if at all |
|
|
728 | \& (active idle watchers, EVLOOP_NONBLOCK or not having |
|
|
729 | \& any active watchers at all will result in not sleeping). |
|
|
730 | \& \- Sleep if the I/O and timer collect interval say so. |
667 | \& - Block the process, waiting for any events. |
731 | \& \- Block the process, waiting for any events. |
668 | \& - Queue all outstanding I/O (fd) events. |
732 | \& \- Queue all outstanding I/O (fd) events. |
669 | \& - Update the "event loop time" and do time jump handling. |
733 | \& \- Update the "event loop time" and do time jump handling. |
670 | \& - Queue all outstanding timers. |
734 | \& \- Queue all outstanding timers. |
671 | \& - Queue all outstanding periodics. |
735 | \& \- Queue all outstanding periodics. |
672 | \& - If no events are pending now, queue all idle watchers. |
736 | \& \- If no events are pending now, queue all idle watchers. |
673 | \& - Queue all check watchers. |
737 | \& \- Queue all check watchers. |
674 | \& - Call all queued watchers in reverse order (i.e. check watchers first). |
738 | \& \- Call all queued watchers in reverse order (i.e. check watchers first). |
675 | \& Signals and child watchers are implemented as I/O watchers, and will |
739 | \& Signals and child watchers are implemented as I/O watchers, and will |
676 | \& be handled here by queueing them when their watcher gets executed. |
740 | \& be handled here by queueing them when their watcher gets executed. |
677 | \& - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
741 | \& \- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
678 | \& were used, return, otherwise continue with step *. |
742 | \& were used, or there are no active watchers, return, otherwise |
|
|
743 | \& continue with step *. |
679 | .Ve |
744 | .Ve |
680 | .Sp |
745 | .Sp |
681 | Example: Queue some jobs and then loop until no events are outsanding |
746 | Example: Queue some jobs and then loop until no events are outstanding |
682 | anymore. |
747 | anymore. |
683 | .Sp |
748 | .Sp |
684 | .Vb 4 |
749 | .Vb 4 |
685 | \& ... queue jobs here, make sure they register event watchers as long |
750 | \& ... queue jobs here, make sure they register event watchers as long |
686 | \& ... as they still have work to do (even an idle watcher will do..) |
751 | \& ... as they still have work to do (even an idle watcher will do..) |
… | |
… | |
691 | .IX Item "ev_unloop (loop, how)" |
756 | .IX Item "ev_unloop (loop, how)" |
692 | Can be used to make a call to \f(CW\*(C`ev_loop\*(C'\fR return early (but only after it |
757 | Can be used to make a call to \f(CW\*(C`ev_loop\*(C'\fR return early (but only after it |
693 | has processed all outstanding events). The \f(CW\*(C`how\*(C'\fR argument must be either |
758 | has processed all outstanding events). The \f(CW\*(C`how\*(C'\fR argument must be either |
694 | \&\f(CW\*(C`EVUNLOOP_ONE\*(C'\fR, which will make the innermost \f(CW\*(C`ev_loop\*(C'\fR call return, or |
759 | \&\f(CW\*(C`EVUNLOOP_ONE\*(C'\fR, which will make the innermost \f(CW\*(C`ev_loop\*(C'\fR call return, or |
695 | \&\f(CW\*(C`EVUNLOOP_ALL\*(C'\fR, which will make all nested \f(CW\*(C`ev_loop\*(C'\fR calls return. |
760 | \&\f(CW\*(C`EVUNLOOP_ALL\*(C'\fR, which will make all nested \f(CW\*(C`ev_loop\*(C'\fR calls return. |
|
|
761 | .Sp |
|
|
762 | This \*(L"unloop state\*(R" will be cleared when entering \f(CW\*(C`ev_loop\*(C'\fR again. |
696 | .IP "ev_ref (loop)" 4 |
763 | .IP "ev_ref (loop)" 4 |
697 | .IX Item "ev_ref (loop)" |
764 | .IX Item "ev_ref (loop)" |
698 | .PD 0 |
765 | .PD 0 |
699 | .IP "ev_unref (loop)" 4 |
766 | .IP "ev_unref (loop)" 4 |
700 | .IX Item "ev_unref (loop)" |
767 | .IX Item "ev_unref (loop)" |
… | |
… | |
706 | returning, \fIev_unref()\fR after starting, and \fIev_ref()\fR before stopping it. For |
773 | returning, \fIev_unref()\fR after starting, and \fIev_ref()\fR before stopping it. For |
707 | example, libev itself uses this for its internal signal pipe: It is not |
774 | example, libev itself uses this for its internal signal pipe: It is not |
708 | visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from exiting if |
775 | visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from exiting if |
709 | no event watchers registered by it are active. It is also an excellent |
776 | no event watchers registered by it are active. It is also an excellent |
710 | way to do this for generic recurring timers or from within third-party |
777 | way to do this for generic recurring timers or from within third-party |
711 | libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR. |
778 | libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR |
|
|
779 | (but only if the watcher wasn't active before, or was active before, |
|
|
780 | respectively). |
712 | .Sp |
781 | .Sp |
713 | Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR |
782 | Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR |
714 | running when nothing else is active. |
783 | running when nothing else is active. |
715 | .Sp |
784 | .Sp |
716 | .Vb 4 |
785 | .Vb 4 |
… | |
… | |
724 | .Sp |
793 | .Sp |
725 | .Vb 2 |
794 | .Vb 2 |
726 | \& ev_ref (loop); |
795 | \& ev_ref (loop); |
727 | \& ev_signal_stop (loop, &exitsig); |
796 | \& ev_signal_stop (loop, &exitsig); |
728 | .Ve |
797 | .Ve |
|
|
798 | .IP "ev_set_io_collect_interval (loop, ev_tstamp interval)" 4 |
|
|
799 | .IX Item "ev_set_io_collect_interval (loop, ev_tstamp interval)" |
|
|
800 | .PD 0 |
|
|
801 | .IP "ev_set_timeout_collect_interval (loop, ev_tstamp interval)" 4 |
|
|
802 | .IX Item "ev_set_timeout_collect_interval (loop, ev_tstamp interval)" |
|
|
803 | .PD |
|
|
804 | These advanced functions influence the time that libev will spend waiting |
|
|
805 | for events. Both are by default \f(CW0\fR, meaning that libev will try to |
|
|
806 | invoke timer/periodic callbacks and I/O callbacks with minimum latency. |
|
|
807 | .Sp |
|
|
808 | Setting these to a higher value (the \f(CW\*(C`interval\*(C'\fR \fImust\fR be >= \f(CW0\fR) |
|
|
809 | allows libev to delay invocation of I/O and timer/periodic callbacks to |
|
|
810 | increase efficiency of loop iterations. |
|
|
811 | .Sp |
|
|
812 | The background is that sometimes your program runs just fast enough to |
|
|
813 | handle one (or very few) event(s) per loop iteration. While this makes |
|
|
814 | the program responsive, it also wastes a lot of \s-1CPU\s0 time to poll for new |
|
|
815 | events, especially with backends like \f(CW\*(C`select ()\*(C'\fR which have a high |
|
|
816 | overhead for the actual polling but can deliver many events at once. |
|
|
817 | .Sp |
|
|
818 | By setting a higher \fIio collect interval\fR you allow libev to spend more |
|
|
819 | time collecting I/O events, so you can handle more events per iteration, |
|
|
820 | at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and |
|
|
821 | \&\f(CW\*(C`ev_timer\*(C'\fR) will be not affected. Setting this to a non-null value will |
|
|
822 | introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations. |
|
|
823 | .Sp |
|
|
824 | Likewise, by setting a higher \fItimeout collect interval\fR you allow libev |
|
|
825 | to spend more time collecting timeouts, at the expense of increased |
|
|
826 | latency (the watcher callback will be called later). \f(CW\*(C`ev_io\*(C'\fR watchers |
|
|
827 | will not be affected. Setting this to a non-null value will not introduce |
|
|
828 | any overhead in libev. |
|
|
829 | .Sp |
|
|
830 | Many (busy) programs can usually benefit by setting the io collect |
|
|
831 | interval to a value near \f(CW0.1\fR or so, which is often enough for |
|
|
832 | interactive servers (of course not for games), likewise for timeouts. It |
|
|
833 | usually doesn't make much sense to set it to a lower value than \f(CW0.01\fR, |
|
|
834 | as this approsaches the timing granularity of most systems. |
729 | .SH "ANATOMY OF A WATCHER" |
835 | .SH "ANATOMY OF A WATCHER" |
730 | .IX Header "ANATOMY OF A WATCHER" |
836 | .IX Header "ANATOMY OF A WATCHER" |
731 | A watcher is a structure that you create and register to record your |
837 | A watcher is a structure that you create and register to record your |
732 | interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to |
838 | interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to |
733 | become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher for that: |
839 | become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher for that: |
… | |
… | |
736 | \& static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
842 | \& static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
737 | \& { |
843 | \& { |
738 | \& ev_io_stop (w); |
844 | \& ev_io_stop (w); |
739 | \& ev_unloop (loop, EVUNLOOP_ALL); |
845 | \& ev_unloop (loop, EVUNLOOP_ALL); |
740 | \& } |
846 | \& } |
741 | .Ve |
847 | \& |
742 | .PP |
|
|
743 | .Vb 6 |
|
|
744 | \& struct ev_loop *loop = ev_default_loop (0); |
848 | \& struct ev_loop *loop = ev_default_loop (0); |
745 | \& struct ev_io stdin_watcher; |
849 | \& struct ev_io stdin_watcher; |
746 | \& ev_init (&stdin_watcher, my_cb); |
850 | \& ev_init (&stdin_watcher, my_cb); |
747 | \& ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
851 | \& ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
748 | \& ev_io_start (loop, &stdin_watcher); |
852 | \& ev_io_start (loop, &stdin_watcher); |
… | |
… | |
836 | .ie n .IP """EV_FORK""" 4 |
940 | .ie n .IP """EV_FORK""" 4 |
837 | .el .IP "\f(CWEV_FORK\fR" 4 |
941 | .el .IP "\f(CWEV_FORK\fR" 4 |
838 | .IX Item "EV_FORK" |
942 | .IX Item "EV_FORK" |
839 | The event loop has been resumed in the child process after fork (see |
943 | The event loop has been resumed in the child process after fork (see |
840 | \&\f(CW\*(C`ev_fork\*(C'\fR). |
944 | \&\f(CW\*(C`ev_fork\*(C'\fR). |
|
|
945 | .ie n .IP """EV_ASYNC""" 4 |
|
|
946 | .el .IP "\f(CWEV_ASYNC\fR" 4 |
|
|
947 | .IX Item "EV_ASYNC" |
|
|
948 | The given async watcher has been asynchronously notified (see \f(CW\*(C`ev_async\*(C'\fR). |
841 | .ie n .IP """EV_ERROR""" 4 |
949 | .ie n .IP """EV_ERROR""" 4 |
842 | .el .IP "\f(CWEV_ERROR\fR" 4 |
950 | .el .IP "\f(CWEV_ERROR\fR" 4 |
843 | .IX Item "EV_ERROR" |
951 | .IX Item "EV_ERROR" |
844 | An unspecified error has occured, the watcher has been stopped. This might |
952 | An unspecified error has occured, the watcher has been stopped. This might |
845 | happen because the watcher could not be properly started because libev |
953 | happen because the watcher could not be properly started because libev |
… | |
… | |
1009 | In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more complicated, |
1117 | In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more complicated, |
1010 | you need to use \f(CW\*(C`offsetof\*(C'\fR: |
1118 | you need to use \f(CW\*(C`offsetof\*(C'\fR: |
1011 | .PP |
1119 | .PP |
1012 | .Vb 1 |
1120 | .Vb 1 |
1013 | \& #include <stddef.h> |
1121 | \& #include <stddef.h> |
1014 | .Ve |
1122 | \& |
1015 | .PP |
|
|
1016 | .Vb 6 |
|
|
1017 | \& static void |
1123 | \& static void |
1018 | \& t1_cb (EV_P_ struct ev_timer *w, int revents) |
1124 | \& t1_cb (EV_P_ struct ev_timer *w, int revents) |
1019 | \& { |
1125 | \& { |
1020 | \& struct my_biggy big = (struct my_biggy * |
1126 | \& struct my_biggy big = (struct my_biggy * |
1021 | \& (((char *)w) - offsetof (struct my_biggy, t1)); |
1127 | \& (((char *)w) \- offsetof (struct my_biggy, t1)); |
1022 | \& } |
1128 | \& } |
1023 | .Ve |
1129 | \& |
1024 | .PP |
|
|
1025 | .Vb 6 |
|
|
1026 | \& static void |
1130 | \& static void |
1027 | \& t2_cb (EV_P_ struct ev_timer *w, int revents) |
1131 | \& t2_cb (EV_P_ struct ev_timer *w, int revents) |
1028 | \& { |
1132 | \& { |
1029 | \& struct my_biggy big = (struct my_biggy * |
1133 | \& struct my_biggy big = (struct my_biggy * |
1030 | \& (((char *)w) - offsetof (struct my_biggy, t2)); |
1134 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
1031 | \& } |
1135 | \& } |
1032 | .Ve |
1136 | .Ve |
1033 | .SH "WATCHER TYPES" |
1137 | .SH "WATCHER TYPES" |
1034 | .IX Header "WATCHER TYPES" |
1138 | .IX Header "WATCHER TYPES" |
1035 | This section describes each watcher in detail, but will not repeat |
1139 | This section describes each watcher in detail, but will not repeat |
… | |
… | |
1058 | In general you can register as many read and/or write event watchers per |
1162 | In general you can register as many read and/or write event watchers per |
1059 | fd as you want (as long as you don't confuse yourself). Setting all file |
1163 | fd as you want (as long as you don't confuse yourself). Setting all file |
1060 | descriptors to non-blocking mode is also usually a good idea (but not |
1164 | descriptors to non-blocking mode is also usually a good idea (but not |
1061 | required if you know what you are doing). |
1165 | required if you know what you are doing). |
1062 | .PP |
1166 | .PP |
1063 | You have to be careful with dup'ed file descriptors, though. Some backends |
|
|
1064 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
|
|
1065 | descriptors correctly if you register interest in two or more fds pointing |
|
|
1066 | to the same underlying file/socket/etc. description (that is, they share |
|
|
1067 | the same underlying \*(L"file open\*(R"). |
|
|
1068 | .PP |
|
|
1069 | If you must do this, then force the use of a known-to-be-good backend |
1167 | If you must do this, then force the use of a known-to-be-good backend |
1070 | (at the time of this writing, this includes only \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and |
1168 | (at the time of this writing, this includes only \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and |
1071 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR). |
1169 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR). |
1072 | .PP |
1170 | .PP |
1073 | Another thing you have to watch out for is that it is quite easy to |
1171 | Another thing you have to watch out for is that it is quite easy to |
… | |
… | |
1109 | .PP |
1207 | .PP |
1110 | \fIThe special problem of dup'ed file descriptors\fR |
1208 | \fIThe special problem of dup'ed file descriptors\fR |
1111 | .IX Subsection "The special problem of dup'ed file descriptors" |
1209 | .IX Subsection "The special problem of dup'ed file descriptors" |
1112 | .PP |
1210 | .PP |
1113 | Some backends (e.g. epoll), cannot register events for file descriptors, |
1211 | Some backends (e.g. epoll), cannot register events for file descriptors, |
1114 | but only events for the underlying file descriptions. That menas when you |
1212 | but only events for the underlying file descriptions. That means when you |
1115 | have \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors and register events for them, only one |
1213 | have \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors or weirder constellations, and register |
1116 | file descriptor might actually receive events. |
1214 | events for them, only one file descriptor might actually receive events. |
1117 | .PP |
1215 | .PP |
1118 | There is no workaorund possible except not registering events |
1216 | There is no workaround possible except not registering events |
1119 | for potentially \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors or to resort to |
1217 | for potentially \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors, or to resort to |
1120 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
1218 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
1121 | .PP |
1219 | .PP |
1122 | \fIThe special problem of fork\fR |
1220 | \fIThe special problem of fork\fR |
1123 | .IX Subsection "The special problem of fork" |
1221 | .IX Subsection "The special problem of fork" |
1124 | .PP |
1222 | .PP |
… | |
… | |
1128 | .PP |
1226 | .PP |
1129 | To support fork in your programs, you either have to call |
1227 | To support fork in your programs, you either have to call |
1130 | \&\f(CW\*(C`ev_default_fork ()\*(C'\fR or \f(CW\*(C`ev_loop_fork ()\*(C'\fR after a fork in the child, |
1228 | \&\f(CW\*(C`ev_default_fork ()\*(C'\fR or \f(CW\*(C`ev_loop_fork ()\*(C'\fR after a fork in the child, |
1131 | enable \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR, or resort to \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or |
1229 | enable \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR, or resort to \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or |
1132 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
1230 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
|
|
1231 | .PP |
|
|
1232 | \fIThe special problem of \s-1SIGPIPE\s0\fR |
|
|
1233 | .IX Subsection "The special problem of SIGPIPE" |
|
|
1234 | .PP |
|
|
1235 | While not really specific to libev, it is easy to forget about \s-1SIGPIPE:\s0 |
|
|
1236 | when reading from a pipe whose other end has been closed, your program |
|
|
1237 | gets send a \s-1SIGPIPE\s0, which, by default, aborts your program. For most |
|
|
1238 | programs this is sensible behaviour, for daemons, this is usually |
|
|
1239 | undesirable. |
|
|
1240 | .PP |
|
|
1241 | So when you encounter spurious, unexplained daemon exits, make sure you |
|
|
1242 | ignore \s-1SIGPIPE\s0 (and maybe make sure you log the exit status of your daemon |
|
|
1243 | somewhere, as that would have given you a big clue). |
1133 | .PP |
1244 | .PP |
1134 | \fIWatcher-Specific Functions\fR |
1245 | \fIWatcher-Specific Functions\fR |
1135 | .IX Subsection "Watcher-Specific Functions" |
1246 | .IX Subsection "Watcher-Specific Functions" |
1136 | .IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 |
1247 | .IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 |
1137 | .IX Item "ev_io_init (ev_io *, callback, int fd, int events)" |
1248 | .IX Item "ev_io_init (ev_io *, callback, int fd, int events)" |
… | |
… | |
1147 | The file descriptor being watched. |
1258 | The file descriptor being watched. |
1148 | .IP "int events [read\-only]" 4 |
1259 | .IP "int events [read\-only]" 4 |
1149 | .IX Item "int events [read-only]" |
1260 | .IX Item "int events [read-only]" |
1150 | The events being watched. |
1261 | The events being watched. |
1151 | .PP |
1262 | .PP |
|
|
1263 | \fIExamples\fR |
|
|
1264 | .IX Subsection "Examples" |
|
|
1265 | .PP |
1152 | Example: Call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well |
1266 | Example: Call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well |
1153 | readable, but only once. Since it is likely line\-buffered, you could |
1267 | readable, but only once. Since it is likely line-buffered, you could |
1154 | attempt to read a whole line in the callback. |
1268 | attempt to read a whole line in the callback. |
1155 | .PP |
1269 | .PP |
1156 | .Vb 6 |
1270 | .Vb 6 |
1157 | \& static void |
1271 | \& static void |
1158 | \& stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1272 | \& stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1159 | \& { |
1273 | \& { |
1160 | \& ev_io_stop (loop, w); |
1274 | \& ev_io_stop (loop, w); |
1161 | \& .. read from stdin here (or from w->fd) and haqndle any I/O errors |
1275 | \& .. read from stdin here (or from w\->fd) and haqndle any I/O errors |
1162 | \& } |
1276 | \& } |
1163 | .Ve |
1277 | \& |
1164 | .PP |
|
|
1165 | .Vb 6 |
|
|
1166 | \& ... |
1278 | \& ... |
1167 | \& struct ev_loop *loop = ev_default_init (0); |
1279 | \& struct ev_loop *loop = ev_default_init (0); |
1168 | \& struct ev_io stdin_readable; |
1280 | \& struct ev_io stdin_readable; |
1169 | \& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1281 | \& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1170 | \& ev_io_start (loop, &stdin_readable); |
1282 | \& ev_io_start (loop, &stdin_readable); |
… | |
… | |
1187 | of the event triggering whatever timeout you are modifying/starting. If |
1299 | of the event triggering whatever timeout you are modifying/starting. If |
1188 | you suspect event processing to be delayed and you \fIneed\fR to base the timeout |
1300 | you suspect event processing to be delayed and you \fIneed\fR to base the timeout |
1189 | on the current time, use something like this to adjust for this: |
1301 | on the current time, use something like this to adjust for this: |
1190 | .PP |
1302 | .PP |
1191 | .Vb 1 |
1303 | .Vb 1 |
1192 | \& ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
1304 | \& ev_timer_set (&timer, after + ev_now () \- ev_time (), 0.); |
1193 | .Ve |
1305 | .Ve |
1194 | .PP |
1306 | .PP |
1195 | The callback is guarenteed to be invoked only when its timeout has passed, |
1307 | The callback is guarenteed to be invoked only when its timeout has passed, |
1196 | but if multiple timers become ready during the same loop iteration then |
1308 | but if multiple timers become ready during the same loop iteration then |
1197 | order of execution is undefined. |
1309 | order of execution is undefined. |
… | |
… | |
1212 | The timer itself will do a best-effort at avoiding drift, that is, if you |
1324 | The timer itself will do a best-effort at avoiding drift, that is, if you |
1213 | configure a timer to trigger every 10 seconds, then it will trigger at |
1325 | configure a timer to trigger every 10 seconds, then it will trigger at |
1214 | exactly 10 second intervals. If, however, your program cannot keep up with |
1326 | exactly 10 second intervals. If, however, your program cannot keep up with |
1215 | the timer (because it takes longer than those 10 seconds to do stuff) the |
1327 | the timer (because it takes longer than those 10 seconds to do stuff) the |
1216 | timer will not fire more than once per event loop iteration. |
1328 | timer will not fire more than once per event loop iteration. |
1217 | .IP "ev_timer_again (loop)" 4 |
1329 | .IP "ev_timer_again (loop, ev_timer *)" 4 |
1218 | .IX Item "ev_timer_again (loop)" |
1330 | .IX Item "ev_timer_again (loop, ev_timer *)" |
1219 | This will act as if the timer timed out and restart it again if it is |
1331 | This will act as if the timer timed out and restart it again if it is |
1220 | repeating. The exact semantics are: |
1332 | repeating. The exact semantics are: |
1221 | .Sp |
1333 | .Sp |
1222 | If the timer is pending, its pending status is cleared. |
1334 | If the timer is pending, its pending status is cleared. |
1223 | .Sp |
1335 | .Sp |
… | |
… | |
1241 | .Sp |
1353 | .Sp |
1242 | .Vb 8 |
1354 | .Vb 8 |
1243 | \& ev_timer_init (timer, callback, 0., 5.); |
1355 | \& ev_timer_init (timer, callback, 0., 5.); |
1244 | \& ev_timer_again (loop, timer); |
1356 | \& ev_timer_again (loop, timer); |
1245 | \& ... |
1357 | \& ... |
1246 | \& timer->again = 17.; |
1358 | \& timer\->again = 17.; |
1247 | \& ev_timer_again (loop, timer); |
1359 | \& ev_timer_again (loop, timer); |
1248 | \& ... |
1360 | \& ... |
1249 | \& timer->again = 10.; |
1361 | \& timer\->again = 10.; |
1250 | \& ev_timer_again (loop, timer); |
1362 | \& ev_timer_again (loop, timer); |
1251 | .Ve |
1363 | .Ve |
1252 | .Sp |
1364 | .Sp |
1253 | This is more slightly efficient then stopping/starting the timer each time |
1365 | This is more slightly efficient then stopping/starting the timer each time |
1254 | you want to modify its timeout value. |
1366 | you want to modify its timeout value. |
… | |
… | |
1256 | .IX Item "ev_tstamp repeat [read-write]" |
1368 | .IX Item "ev_tstamp repeat [read-write]" |
1257 | The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out |
1369 | The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out |
1258 | or \f(CW\*(C`ev_timer_again\*(C'\fR is called and determines the next timeout (if any), |
1370 | or \f(CW\*(C`ev_timer_again\*(C'\fR is called and determines the next timeout (if any), |
1259 | which is also when any modifications are taken into account. |
1371 | which is also when any modifications are taken into account. |
1260 | .PP |
1372 | .PP |
|
|
1373 | \fIExamples\fR |
|
|
1374 | .IX Subsection "Examples" |
|
|
1375 | .PP |
1261 | Example: Create a timer that fires after 60 seconds. |
1376 | Example: Create a timer that fires after 60 seconds. |
1262 | .PP |
1377 | .PP |
1263 | .Vb 5 |
1378 | .Vb 5 |
1264 | \& static void |
1379 | \& static void |
1265 | \& one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1380 | \& one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1266 | \& { |
1381 | \& { |
1267 | \& .. one minute over, w is actually stopped right here |
1382 | \& .. one minute over, w is actually stopped right here |
1268 | \& } |
1383 | \& } |
1269 | .Ve |
1384 | \& |
1270 | .PP |
|
|
1271 | .Vb 3 |
|
|
1272 | \& struct ev_timer mytimer; |
1385 | \& struct ev_timer mytimer; |
1273 | \& ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
1386 | \& ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
1274 | \& ev_timer_start (loop, &mytimer); |
1387 | \& ev_timer_start (loop, &mytimer); |
1275 | .Ve |
1388 | .Ve |
1276 | .PP |
1389 | .PP |
… | |
… | |
1281 | \& static void |
1394 | \& static void |
1282 | \& timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1395 | \& timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1283 | \& { |
1396 | \& { |
1284 | \& .. ten seconds without any activity |
1397 | \& .. ten seconds without any activity |
1285 | \& } |
1398 | \& } |
1286 | .Ve |
1399 | \& |
1287 | .PP |
|
|
1288 | .Vb 4 |
|
|
1289 | \& struct ev_timer mytimer; |
1400 | \& struct ev_timer mytimer; |
1290 | \& ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1401 | \& ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1291 | \& ev_timer_again (&mytimer); /* start timer */ |
1402 | \& ev_timer_again (&mytimer); /* start timer */ |
1292 | \& ev_loop (loop, 0); |
1403 | \& ev_loop (loop, 0); |
1293 | .Ve |
1404 | \& |
1294 | .PP |
|
|
1295 | .Vb 3 |
|
|
1296 | \& // and in some piece of code that gets executed on any "activity": |
1405 | \& // and in some piece of code that gets executed on any "activity": |
1297 | \& // reset the timeout to start ticking again at 10 seconds |
1406 | \& // reset the timeout to start ticking again at 10 seconds |
1298 | \& ev_timer_again (&mytimer); |
1407 | \& ev_timer_again (&mytimer); |
1299 | .Ve |
1408 | .Ve |
1300 | .ie n .Sh """ev_periodic"" \- to cron or not to cron?" |
1409 | .ie n .Sh """ev_periodic"" \- to cron or not to cron?" |
… | |
… | |
1328 | .IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" |
1437 | .IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" |
1329 | .PD |
1438 | .PD |
1330 | Lots of arguments, lets sort it out... There are basically three modes of |
1439 | Lots of arguments, lets sort it out... There are basically three modes of |
1331 | operation, and we will explain them from simplest to complex: |
1440 | operation, and we will explain them from simplest to complex: |
1332 | .RS 4 |
1441 | .RS 4 |
|
|
1442 | .IP "\(bu" 4 |
1333 | .IP "* absolute timer (at = time, interval = reschedule_cb = 0)" 4 |
1443 | absolute timer (at = time, interval = reschedule_cb = 0) |
1334 | .IX Item "absolute timer (at = time, interval = reschedule_cb = 0)" |
1444 | .Sp |
1335 | In this configuration the watcher triggers an event at the wallclock time |
1445 | In this configuration the watcher triggers an event at the wallclock time |
1336 | \&\f(CW\*(C`at\*(C'\fR and doesn't repeat. It will not adjust when a time jump occurs, |
1446 | \&\f(CW\*(C`at\*(C'\fR and doesn't repeat. It will not adjust when a time jump occurs, |
1337 | that is, if it is to be run at January 1st 2011 then it will run when the |
1447 | that is, if it is to be run at January 1st 2011 then it will run when the |
1338 | system time reaches or surpasses this time. |
1448 | system time reaches or surpasses this time. |
|
|
1449 | .IP "\(bu" 4 |
1339 | .IP "* non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)" 4 |
1450 | repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
1340 | .IX Item "non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)" |
1451 | .Sp |
1341 | In this mode the watcher will always be scheduled to time out at the next |
1452 | In this mode the watcher will always be scheduled to time out at the next |
1342 | \&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N, which can also be negative) |
1453 | \&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N, which can also be negative) |
1343 | and then repeat, regardless of any time jumps. |
1454 | and then repeat, regardless of any time jumps. |
1344 | .Sp |
1455 | .Sp |
1345 | This can be used to create timers that do not drift with respect to system |
1456 | This can be used to create timers that do not drift with respect to system |
… | |
… | |
1359 | time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps. |
1470 | time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps. |
1360 | .Sp |
1471 | .Sp |
1361 | For numerical stability it is preferable that the \f(CW\*(C`at\*(C'\fR value is near |
1472 | For numerical stability it is preferable that the \f(CW\*(C`at\*(C'\fR value is near |
1362 | \&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for |
1473 | \&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for |
1363 | this value. |
1474 | this value. |
|
|
1475 | .IP "\(bu" 4 |
1364 | .IP "* manual reschedule mode (at and interval ignored, reschedule_cb = callback)" 4 |
1476 | manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
1365 | .IX Item "manual reschedule mode (at and interval ignored, reschedule_cb = callback)" |
1477 | .Sp |
1366 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being |
1478 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being |
1367 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1479 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1368 | reschedule callback will be called with the watcher as first, and the |
1480 | reschedule callback will be called with the watcher as first, and the |
1369 | current time as second argument. |
1481 | current time as second argument. |
1370 | .Sp |
1482 | .Sp |
… | |
… | |
1425 | .IP "ev_tstamp at [read\-only]" 4 |
1537 | .IP "ev_tstamp at [read\-only]" 4 |
1426 | .IX Item "ev_tstamp at [read-only]" |
1538 | .IX Item "ev_tstamp at [read-only]" |
1427 | When active, contains the absolute time that the watcher is supposed to |
1539 | When active, contains the absolute time that the watcher is supposed to |
1428 | trigger next. |
1540 | trigger next. |
1429 | .PP |
1541 | .PP |
|
|
1542 | \fIExamples\fR |
|
|
1543 | .IX Subsection "Examples" |
|
|
1544 | .PP |
1430 | Example: Call a callback every hour, or, more precisely, whenever the |
1545 | Example: Call a callback every hour, or, more precisely, whenever the |
1431 | system clock is divisible by 3600. The callback invocation times have |
1546 | system clock is divisible by 3600. The callback invocation times have |
1432 | potentially a lot of jittering, but good long-term stability. |
1547 | potentially a lot of jittering, but good long-term stability. |
1433 | .PP |
1548 | .PP |
1434 | .Vb 5 |
1549 | .Vb 5 |
1435 | \& static void |
1550 | \& static void |
1436 | \& clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1551 | \& clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1437 | \& { |
1552 | \& { |
1438 | \& ... its now a full hour (UTC, or TAI or whatever your clock follows) |
1553 | \& ... its now a full hour (UTC, or TAI or whatever your clock follows) |
1439 | \& } |
1554 | \& } |
1440 | .Ve |
1555 | \& |
1441 | .PP |
|
|
1442 | .Vb 3 |
|
|
1443 | \& struct ev_periodic hourly_tick; |
1556 | \& struct ev_periodic hourly_tick; |
1444 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1557 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1445 | \& ev_periodic_start (loop, &hourly_tick); |
1558 | \& ev_periodic_start (loop, &hourly_tick); |
1446 | .Ve |
1559 | .Ve |
1447 | .PP |
1560 | .PP |
1448 | Example: The same as above, but use a reschedule callback to do it: |
1561 | Example: The same as above, but use a reschedule callback to do it: |
1449 | .PP |
1562 | .PP |
1450 | .Vb 1 |
1563 | .Vb 1 |
1451 | \& #include <math.h> |
1564 | \& #include <math.h> |
1452 | .Ve |
1565 | \& |
1453 | .PP |
|
|
1454 | .Vb 5 |
|
|
1455 | \& static ev_tstamp |
1566 | \& static ev_tstamp |
1456 | \& my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
1567 | \& my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
1457 | \& { |
1568 | \& { |
1458 | \& return fmod (now, 3600.) + 3600.; |
1569 | \& return fmod (now, 3600.) + 3600.; |
1459 | \& } |
1570 | \& } |
1460 | .Ve |
1571 | \& |
1461 | .PP |
|
|
1462 | .Vb 1 |
|
|
1463 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1572 | \& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1464 | .Ve |
1573 | .Ve |
1465 | .PP |
1574 | .PP |
1466 | Example: Call a callback every hour, starting now: |
1575 | Example: Call a callback every hour, starting now: |
1467 | .PP |
1576 | .PP |
… | |
… | |
1483 | first watcher gets started will libev actually register a signal watcher |
1592 | first watcher gets started will libev actually register a signal watcher |
1484 | with the kernel (thus it coexists with your own signal handlers as long |
1593 | with the kernel (thus it coexists with your own signal handlers as long |
1485 | as you don't register any with libev). Similarly, when the last signal |
1594 | as you don't register any with libev). Similarly, when the last signal |
1486 | watcher for a signal is stopped libev will reset the signal handler to |
1595 | watcher for a signal is stopped libev will reset the signal handler to |
1487 | \&\s-1SIG_DFL\s0 (regardless of what it was set to before). |
1596 | \&\s-1SIG_DFL\s0 (regardless of what it was set to before). |
|
|
1597 | .PP |
|
|
1598 | If possible and supported, libev will install its handlers with |
|
|
1599 | \&\f(CW\*(C`SA_RESTART\*(C'\fR behaviour enabled, so syscalls should not be unduly |
|
|
1600 | interrupted. If you have a problem with syscalls getting interrupted by |
|
|
1601 | signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher and unblock |
|
|
1602 | them in an \f(CW\*(C`ev_prepare\*(C'\fR watcher. |
1488 | .PP |
1603 | .PP |
1489 | \fIWatcher-Specific Functions and Data Members\fR |
1604 | \fIWatcher-Specific Functions and Data Members\fR |
1490 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1605 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1491 | .IP "ev_signal_init (ev_signal *, callback, int signum)" 4 |
1606 | .IP "ev_signal_init (ev_signal *, callback, int signum)" 4 |
1492 | .IX Item "ev_signal_init (ev_signal *, callback, int signum)" |
1607 | .IX Item "ev_signal_init (ev_signal *, callback, int signum)" |
… | |
… | |
1497 | Configures the watcher to trigger on the given signal number (usually one |
1612 | Configures the watcher to trigger on the given signal number (usually one |
1498 | of the \f(CW\*(C`SIGxxx\*(C'\fR constants). |
1613 | of the \f(CW\*(C`SIGxxx\*(C'\fR constants). |
1499 | .IP "int signum [read\-only]" 4 |
1614 | .IP "int signum [read\-only]" 4 |
1500 | .IX Item "int signum [read-only]" |
1615 | .IX Item "int signum [read-only]" |
1501 | The signal the watcher watches out for. |
1616 | The signal the watcher watches out for. |
|
|
1617 | .PP |
|
|
1618 | \fIExamples\fR |
|
|
1619 | .IX Subsection "Examples" |
|
|
1620 | .PP |
|
|
1621 | Example: Try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0. |
|
|
1622 | .PP |
|
|
1623 | .Vb 5 |
|
|
1624 | \& static void |
|
|
1625 | \& sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
|
|
1626 | \& { |
|
|
1627 | \& ev_unloop (loop, EVUNLOOP_ALL); |
|
|
1628 | \& } |
|
|
1629 | \& |
|
|
1630 | \& struct ev_signal signal_watcher; |
|
|
1631 | \& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
|
|
1632 | \& ev_signal_start (loop, &sigint_cb); |
|
|
1633 | .Ve |
1502 | .ie n .Sh """ev_child"" \- watch out for process status changes" |
1634 | .ie n .Sh """ev_child"" \- watch out for process status changes" |
1503 | .el .Sh "\f(CWev_child\fP \- watch out for process status changes" |
1635 | .el .Sh "\f(CWev_child\fP \- watch out for process status changes" |
1504 | .IX Subsection "ev_child - watch out for process status changes" |
1636 | .IX Subsection "ev_child - watch out for process status changes" |
1505 | Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to |
1637 | Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to |
1506 | some child status changes (most typically when a child of yours dies). |
1638 | some child status changes (most typically when a child of yours dies). It |
|
|
1639 | is permissible to install a child watcher \fIafter\fR the child has been |
|
|
1640 | forked (which implies it might have already exited), as long as the event |
|
|
1641 | loop isn't entered (or is continued from a watcher). |
|
|
1642 | .PP |
|
|
1643 | Only the default event loop is capable of handling signals, and therefore |
|
|
1644 | you can only rgeister child watchers in the default event loop. |
|
|
1645 | .PP |
|
|
1646 | \fIProcess Interaction\fR |
|
|
1647 | .IX Subsection "Process Interaction" |
|
|
1648 | .PP |
|
|
1649 | Libev grabs \f(CW\*(C`SIGCHLD\*(C'\fR as soon as the default event loop is |
|
|
1650 | initialised. This is necessary to guarantee proper behaviour even if |
|
|
1651 | the first child watcher is started after the child exits. The occurance |
|
|
1652 | of \f(CW\*(C`SIGCHLD\*(C'\fR is recorded asynchronously, but child reaping is done |
|
|
1653 | synchronously as part of the event loop processing. Libev always reaps all |
|
|
1654 | children, even ones not watched. |
|
|
1655 | .PP |
|
|
1656 | \fIOverriding the Built-In Processing\fR |
|
|
1657 | .IX Subsection "Overriding the Built-In Processing" |
|
|
1658 | .PP |
|
|
1659 | Libev offers no special support for overriding the built-in child |
|
|
1660 | processing, but if your application collides with libev's default child |
|
|
1661 | handler, you can override it easily by installing your own handler for |
|
|
1662 | \&\f(CW\*(C`SIGCHLD\*(C'\fR after initialising the default loop, and making sure the |
|
|
1663 | default loop never gets destroyed. You are encouraged, however, to use an |
|
|
1664 | event-based approach to child reaping and thus use libev's support for |
|
|
1665 | that, so other libev users can use \f(CW\*(C`ev_child\*(C'\fR watchers freely. |
1507 | .PP |
1666 | .PP |
1508 | \fIWatcher-Specific Functions and Data Members\fR |
1667 | \fIWatcher-Specific Functions and Data Members\fR |
1509 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1668 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1510 | .IP "ev_child_init (ev_child *, callback, int pid)" 4 |
1669 | .IP "ev_child_init (ev_child *, callback, int pid, int trace)" 4 |
1511 | .IX Item "ev_child_init (ev_child *, callback, int pid)" |
1670 | .IX Item "ev_child_init (ev_child *, callback, int pid, int trace)" |
1512 | .PD 0 |
1671 | .PD 0 |
1513 | .IP "ev_child_set (ev_child *, int pid)" 4 |
1672 | .IP "ev_child_set (ev_child *, int pid, int trace)" 4 |
1514 | .IX Item "ev_child_set (ev_child *, int pid)" |
1673 | .IX Item "ev_child_set (ev_child *, int pid, int trace)" |
1515 | .PD |
1674 | .PD |
1516 | Configures the watcher to wait for status changes of process \f(CW\*(C`pid\*(C'\fR (or |
1675 | Configures the watcher to wait for status changes of process \f(CW\*(C`pid\*(C'\fR (or |
1517 | \&\fIany\fR process if \f(CW\*(C`pid\*(C'\fR is specified as \f(CW0\fR). The callback can look |
1676 | \&\fIany\fR process if \f(CW\*(C`pid\*(C'\fR is specified as \f(CW0\fR). The callback can look |
1518 | at the \f(CW\*(C`rstatus\*(C'\fR member of the \f(CW\*(C`ev_child\*(C'\fR watcher structure to see |
1677 | at the \f(CW\*(C`rstatus\*(C'\fR member of the \f(CW\*(C`ev_child\*(C'\fR watcher structure to see |
1519 | the status word (use the macros from \f(CW\*(C`sys/wait.h\*(C'\fR and see your systems |
1678 | the status word (use the macros from \f(CW\*(C`sys/wait.h\*(C'\fR and see your systems |
1520 | \&\f(CW\*(C`waitpid\*(C'\fR documentation). The \f(CW\*(C`rpid\*(C'\fR member contains the pid of the |
1679 | \&\f(CW\*(C`waitpid\*(C'\fR documentation). The \f(CW\*(C`rpid\*(C'\fR member contains the pid of the |
1521 | process causing the status change. |
1680 | process causing the status change. \f(CW\*(C`trace\*(C'\fR must be either \f(CW0\fR (only |
|
|
1681 | activate the watcher when the process terminates) or \f(CW1\fR (additionally |
|
|
1682 | activate the watcher when the process is stopped or continued). |
1522 | .IP "int pid [read\-only]" 4 |
1683 | .IP "int pid [read\-only]" 4 |
1523 | .IX Item "int pid [read-only]" |
1684 | .IX Item "int pid [read-only]" |
1524 | The process id this watcher watches out for, or \f(CW0\fR, meaning any process id. |
1685 | The process id this watcher watches out for, or \f(CW0\fR, meaning any process id. |
1525 | .IP "int rpid [read\-write]" 4 |
1686 | .IP "int rpid [read\-write]" 4 |
1526 | .IX Item "int rpid [read-write]" |
1687 | .IX Item "int rpid [read-write]" |
… | |
… | |
1528 | .IP "int rstatus [read\-write]" 4 |
1689 | .IP "int rstatus [read\-write]" 4 |
1529 | .IX Item "int rstatus [read-write]" |
1690 | .IX Item "int rstatus [read-write]" |
1530 | The process exit/trace status caused by \f(CW\*(C`rpid\*(C'\fR (see your systems |
1691 | The process exit/trace status caused by \f(CW\*(C`rpid\*(C'\fR (see your systems |
1531 | \&\f(CW\*(C`waitpid\*(C'\fR and \f(CW\*(C`sys/wait.h\*(C'\fR documentation for details). |
1692 | \&\f(CW\*(C`waitpid\*(C'\fR and \f(CW\*(C`sys/wait.h\*(C'\fR documentation for details). |
1532 | .PP |
1693 | .PP |
1533 | Example: Try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0. |
1694 | \fIExamples\fR |
|
|
1695 | .IX Subsection "Examples" |
1534 | .PP |
1696 | .PP |
|
|
1697 | Example: \f(CW\*(C`fork()\*(C'\fR a new process and install a child handler to wait for |
|
|
1698 | its completion. |
|
|
1699 | .PP |
1535 | .Vb 5 |
1700 | .Vb 1 |
|
|
1701 | \& ev_child cw; |
|
|
1702 | \& |
1536 | \& static void |
1703 | \& static void |
1537 | \& sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1704 | \& child_cb (EV_P_ struct ev_child *w, int revents) |
1538 | \& { |
1705 | \& { |
1539 | \& ev_unloop (loop, EVUNLOOP_ALL); |
1706 | \& ev_child_stop (EV_A_ w); |
|
|
1707 | \& printf ("process %d exited with status %x\en", w\->rpid, w\->rstatus); |
1540 | \& } |
1708 | \& } |
1541 | .Ve |
1709 | \& |
1542 | .PP |
1710 | \& pid_t pid = fork (); |
1543 | .Vb 3 |
1711 | \& |
1544 | \& struct ev_signal signal_watcher; |
1712 | \& if (pid < 0) |
1545 | \& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1713 | \& // error |
1546 | \& ev_signal_start (loop, &sigint_cb); |
1714 | \& else if (pid == 0) |
|
|
1715 | \& { |
|
|
1716 | \& // the forked child executes here |
|
|
1717 | \& exit (1); |
|
|
1718 | \& } |
|
|
1719 | \& else |
|
|
1720 | \& { |
|
|
1721 | \& ev_child_init (&cw, child_cb, pid, 0); |
|
|
1722 | \& ev_child_start (EV_DEFAULT_ &cw); |
|
|
1723 | \& } |
1547 | .Ve |
1724 | .Ve |
1548 | .ie n .Sh """ev_stat"" \- did the file attributes just change?" |
1725 | .ie n .Sh """ev_stat"" \- did the file attributes just change?" |
1549 | .el .Sh "\f(CWev_stat\fP \- did the file attributes just change?" |
1726 | .el .Sh "\f(CWev_stat\fP \- did the file attributes just change?" |
1550 | .IX Subsection "ev_stat - did the file attributes just change?" |
1727 | .IX Subsection "ev_stat - did the file attributes just change?" |
1551 | This watches a filesystem path for attribute changes. That is, it calls |
1728 | This watches a filesystem path for attribute changes. That is, it calls |
… | |
… | |
1570 | impose a minimum interval which is currently around \f(CW0.1\fR, but thats |
1747 | impose a minimum interval which is currently around \f(CW0.1\fR, but thats |
1571 | usually overkill. |
1748 | usually overkill. |
1572 | .PP |
1749 | .PP |
1573 | This watcher type is not meant for massive numbers of stat watchers, |
1750 | This watcher type is not meant for massive numbers of stat watchers, |
1574 | as even with OS-supported change notifications, this can be |
1751 | as even with OS-supported change notifications, this can be |
1575 | resource\-intensive. |
1752 | resource-intensive. |
1576 | .PP |
1753 | .PP |
1577 | At the time of this writing, only the Linux inotify interface is |
1754 | At the time of this writing, only the Linux inotify interface is |
1578 | implemented (implementing kqueue support is left as an exercise for the |
1755 | implemented (implementing kqueue support is left as an exercise for the |
1579 | reader). Inotify will be used to give hints only and should not change the |
1756 | reader). Inotify will be used to give hints only and should not change the |
1580 | semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers, which means that libev sometimes needs |
1757 | semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers, which means that libev sometimes needs |
1581 | to fall back to regular polling again even with inotify, but changes are |
1758 | to fall back to regular polling again even with inotify, but changes are |
1582 | usually detected immediately, and if the file exists there will be no |
1759 | usually detected immediately, and if the file exists there will be no |
1583 | polling. |
1760 | polling. |
|
|
1761 | .PP |
|
|
1762 | \fI\s-1ABI\s0 Issues (Largefile Support)\fR |
|
|
1763 | .IX Subsection "ABI Issues (Largefile Support)" |
|
|
1764 | .PP |
|
|
1765 | Libev by default (unless the user overrides this) uses the default |
|
|
1766 | compilation environment, which means that on systems with optionally |
|
|
1767 | disabled large file support, you get the 32 bit version of the stat |
|
|
1768 | structure. When using the library from programs that change the \s-1ABI\s0 to |
|
|
1769 | use 64 bit file offsets the programs will fail. In that case you have to |
|
|
1770 | compile libev with the same flags to get binary compatibility. This is |
|
|
1771 | obviously the case with any flags that change the \s-1ABI\s0, but the problem is |
|
|
1772 | most noticably with ev_stat and largefile support. |
|
|
1773 | .PP |
|
|
1774 | \fIInotify\fR |
|
|
1775 | .IX Subsection "Inotify" |
|
|
1776 | .PP |
|
|
1777 | When \f(CW\*(C`inotify (7)\*(C'\fR support has been compiled into libev (generally only |
|
|
1778 | available on Linux) and present at runtime, it will be used to speed up |
|
|
1779 | change detection where possible. The inotify descriptor will be created lazily |
|
|
1780 | when the first \f(CW\*(C`ev_stat\*(C'\fR watcher is being started. |
|
|
1781 | .PP |
|
|
1782 | Inotify presense does not change the semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers |
|
|
1783 | except that changes might be detected earlier, and in some cases, to avoid |
|
|
1784 | making regular \f(CW\*(C`stat\*(C'\fR calls. Even in the presense of inotify support |
|
|
1785 | there are many cases where libev has to resort to regular \f(CW\*(C`stat\*(C'\fR polling. |
|
|
1786 | .PP |
|
|
1787 | (There is no support for kqueue, as apparently it cannot be used to |
|
|
1788 | implement this functionality, due to the requirement of having a file |
|
|
1789 | descriptor open on the object at all times). |
|
|
1790 | .PP |
|
|
1791 | \fIThe special problem of stat time resolution\fR |
|
|
1792 | .IX Subsection "The special problem of stat time resolution" |
|
|
1793 | .PP |
|
|
1794 | The \f(CW\*(C`stat ()\*(C'\fR syscall only supports full-second resolution portably, and |
|
|
1795 | even on systems where the resolution is higher, many filesystems still |
|
|
1796 | only support whole seconds. |
|
|
1797 | .PP |
|
|
1798 | That means that, if the time is the only thing that changes, you might |
|
|
1799 | miss updates: on the first update, \f(CW\*(C`ev_stat\*(C'\fR detects a change and calls |
|
|
1800 | your callback, which does something. When there is another update within |
|
|
1801 | the same second, \f(CW\*(C`ev_stat\*(C'\fR will be unable to detect it. |
|
|
1802 | .PP |
|
|
1803 | The solution to this is to delay acting on a change for a second (or till |
|
|
1804 | the next second boundary), using a roughly one-second delay \f(CW\*(C`ev_timer\*(C'\fR |
|
|
1805 | (\f(CW\*(C`ev_timer_set (w, 0., 1.01); ev_timer_again (loop, w)\*(C'\fR). The \f(CW.01\fR |
|
|
1806 | is added to work around small timing inconsistencies of some operating |
|
|
1807 | systems. |
1584 | .PP |
1808 | .PP |
1585 | \fIWatcher-Specific Functions and Data Members\fR |
1809 | \fIWatcher-Specific Functions and Data Members\fR |
1586 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1810 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1587 | .IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4 |
1811 | .IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4 |
1588 | .IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" |
1812 | .IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" |
… | |
… | |
1597 | path for as long as the watcher is active. |
1821 | path for as long as the watcher is active. |
1598 | .Sp |
1822 | .Sp |
1599 | The callback will be receive \f(CW\*(C`EV_STAT\*(C'\fR when a change was detected, |
1823 | The callback will be receive \f(CW\*(C`EV_STAT\*(C'\fR when a change was detected, |
1600 | relative to the attributes at the time the watcher was started (or the |
1824 | relative to the attributes at the time the watcher was started (or the |
1601 | last change was detected). |
1825 | last change was detected). |
1602 | .IP "ev_stat_stat (ev_stat *)" 4 |
1826 | .IP "ev_stat_stat (loop, ev_stat *)" 4 |
1603 | .IX Item "ev_stat_stat (ev_stat *)" |
1827 | .IX Item "ev_stat_stat (loop, ev_stat *)" |
1604 | Updates the stat buffer immediately with new values. If you change the |
1828 | Updates the stat buffer immediately with new values. If you change the |
1605 | watched path in your callback, you could call this fucntion to avoid |
1829 | watched path in your callback, you could call this fucntion to avoid |
1606 | detecting this change (while introducing a race condition). Can also be |
1830 | detecting this change (while introducing a race condition). Can also be |
1607 | useful simply to find out the new values. |
1831 | useful simply to find out the new values. |
1608 | .IP "ev_statdata attr [read\-only]" 4 |
1832 | .IP "ev_statdata attr [read\-only]" 4 |
… | |
… | |
1620 | The specified interval. |
1844 | The specified interval. |
1621 | .IP "const char *path [read\-only]" 4 |
1845 | .IP "const char *path [read\-only]" 4 |
1622 | .IX Item "const char *path [read-only]" |
1846 | .IX Item "const char *path [read-only]" |
1623 | The filesystem path that is being watched. |
1847 | The filesystem path that is being watched. |
1624 | .PP |
1848 | .PP |
|
|
1849 | \fIExamples\fR |
|
|
1850 | .IX Subsection "Examples" |
|
|
1851 | .PP |
1625 | Example: Watch \f(CW\*(C`/etc/passwd\*(C'\fR for attribute changes. |
1852 | Example: Watch \f(CW\*(C`/etc/passwd\*(C'\fR for attribute changes. |
1626 | .PP |
1853 | .PP |
1627 | .Vb 15 |
1854 | .Vb 10 |
1628 | \& static void |
1855 | \& static void |
1629 | \& passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
1856 | \& passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
1630 | \& { |
1857 | \& { |
1631 | \& /* /etc/passwd changed in some way */ |
1858 | \& /* /etc/passwd changed in some way */ |
1632 | \& if (w->attr.st_nlink) |
1859 | \& if (w\->attr.st_nlink) |
1633 | \& { |
1860 | \& { |
1634 | \& printf ("passwd current size %ld\en", (long)w->attr.st_size); |
1861 | \& printf ("passwd current size %ld\en", (long)w\->attr.st_size); |
1635 | \& printf ("passwd current atime %ld\en", (long)w->attr.st_mtime); |
1862 | \& printf ("passwd current atime %ld\en", (long)w\->attr.st_mtime); |
1636 | \& printf ("passwd current mtime %ld\en", (long)w->attr.st_mtime); |
1863 | \& printf ("passwd current mtime %ld\en", (long)w\->attr.st_mtime); |
1637 | \& } |
1864 | \& } |
1638 | \& else |
1865 | \& else |
1639 | \& /* you shalt not abuse printf for puts */ |
1866 | \& /* you shalt not abuse printf for puts */ |
1640 | \& puts ("wow, /etc/passwd is not there, expect problems. " |
1867 | \& puts ("wow, /etc/passwd is not there, expect problems. " |
1641 | \& "if this is windows, they already arrived\en"); |
1868 | \& "if this is windows, they already arrived\en"); |
1642 | \& } |
1869 | \& } |
1643 | .Ve |
1870 | \& |
1644 | .PP |
|
|
1645 | .Vb 2 |
|
|
1646 | \& ... |
1871 | \& ... |
1647 | \& ev_stat passwd; |
1872 | \& ev_stat passwd; |
|
|
1873 | \& |
|
|
1874 | \& ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.); |
|
|
1875 | \& ev_stat_start (loop, &passwd); |
1648 | .Ve |
1876 | .Ve |
|
|
1877 | .PP |
|
|
1878 | Example: Like above, but additionally use a one-second delay so we do not |
|
|
1879 | miss updates (however, frequent updates will delay processing, too, so |
|
|
1880 | one might do the work both on \f(CW\*(C`ev_stat\*(C'\fR callback invocation \fIand\fR on |
|
|
1881 | \&\f(CW\*(C`ev_timer\*(C'\fR callback invocation). |
1649 | .PP |
1882 | .PP |
1650 | .Vb 2 |
1883 | .Vb 2 |
|
|
1884 | \& static ev_stat passwd; |
|
|
1885 | \& static ev_timer timer; |
|
|
1886 | \& |
|
|
1887 | \& static void |
|
|
1888 | \& timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1889 | \& { |
|
|
1890 | \& ev_timer_stop (EV_A_ w); |
|
|
1891 | \& |
|
|
1892 | \& /* now it\*(Aqs one second after the most recent passwd change */ |
|
|
1893 | \& } |
|
|
1894 | \& |
|
|
1895 | \& static void |
|
|
1896 | \& stat_cb (EV_P_ ev_stat *w, int revents) |
|
|
1897 | \& { |
|
|
1898 | \& /* reset the one\-second timer */ |
|
|
1899 | \& ev_timer_again (EV_A_ &timer); |
|
|
1900 | \& } |
|
|
1901 | \& |
|
|
1902 | \& ... |
1651 | \& ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
1903 | \& ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
1652 | \& ev_stat_start (loop, &passwd); |
1904 | \& ev_stat_start (loop, &passwd); |
|
|
1905 | \& ev_timer_init (&timer, timer_cb, 0., 1.01); |
1653 | .Ve |
1906 | .Ve |
1654 | .ie n .Sh """ev_idle"" \- when you've got nothing better to do..." |
1907 | .ie n .Sh """ev_idle"" \- when you've got nothing better to do..." |
1655 | .el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..." |
1908 | .el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..." |
1656 | .IX Subsection "ev_idle - when you've got nothing better to do..." |
1909 | .IX Subsection "ev_idle - when you've got nothing better to do..." |
1657 | Idle watchers trigger events when no other events of the same or higher |
1910 | Idle watchers trigger events when no other events of the same or higher |
… | |
… | |
1668 | The most noteworthy effect is that as long as any idle watchers are |
1921 | The most noteworthy effect is that as long as any idle watchers are |
1669 | active, the process will not block when waiting for new events. |
1922 | active, the process will not block when waiting for new events. |
1670 | .PP |
1923 | .PP |
1671 | Apart from keeping your process non-blocking (which is a useful |
1924 | Apart from keeping your process non-blocking (which is a useful |
1672 | effect on its own sometimes), idle watchers are a good place to do |
1925 | effect on its own sometimes), idle watchers are a good place to do |
1673 | \&\*(L"pseudo\-background processing\*(R", or delay processing stuff to after the |
1926 | \&\*(L"pseudo-background processing\*(R", or delay processing stuff to after the |
1674 | event loop has handled all outstanding events. |
1927 | event loop has handled all outstanding events. |
1675 | .PP |
1928 | .PP |
1676 | \fIWatcher-Specific Functions and Data Members\fR |
1929 | \fIWatcher-Specific Functions and Data Members\fR |
1677 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1930 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1678 | .IP "ev_idle_init (ev_signal *, callback)" 4 |
1931 | .IP "ev_idle_init (ev_signal *, callback)" 4 |
1679 | .IX Item "ev_idle_init (ev_signal *, callback)" |
1932 | .IX Item "ev_idle_init (ev_signal *, callback)" |
1680 | Initialises and configures the idle watcher \- it has no parameters of any |
1933 | Initialises and configures the idle watcher \- it has no parameters of any |
1681 | kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, |
1934 | kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, |
1682 | believe me. |
1935 | believe me. |
1683 | .PP |
1936 | .PP |
|
|
1937 | \fIExamples\fR |
|
|
1938 | .IX Subsection "Examples" |
|
|
1939 | .PP |
1684 | Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the |
1940 | Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the |
1685 | callback, free it. Also, use no error checking, as usual. |
1941 | callback, free it. Also, use no error checking, as usual. |
1686 | .PP |
1942 | .PP |
1687 | .Vb 7 |
1943 | .Vb 7 |
1688 | \& static void |
1944 | \& static void |
1689 | \& idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1945 | \& idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1690 | \& { |
1946 | \& { |
1691 | \& free (w); |
1947 | \& free (w); |
1692 | \& // now do something you wanted to do when the program has |
1948 | \& // now do something you wanted to do when the program has |
1693 | \& // no longer asnything immediate to do. |
1949 | \& // no longer anything immediate to do. |
1694 | \& } |
1950 | \& } |
1695 | .Ve |
1951 | \& |
1696 | .PP |
|
|
1697 | .Vb 3 |
|
|
1698 | \& struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1952 | \& struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1699 | \& ev_idle_init (idle_watcher, idle_cb); |
1953 | \& ev_idle_init (idle_watcher, idle_cb); |
1700 | \& ev_idle_start (loop, idle_cb); |
1954 | \& ev_idle_start (loop, idle_cb); |
1701 | .Ve |
1955 | .Ve |
1702 | .ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop!" |
1956 | .ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop!" |
… | |
… | |
1742 | .PP |
1996 | .PP |
1743 | It is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR) |
1997 | It is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR) |
1744 | priority, to ensure that they are being run before any other watchers |
1998 | priority, to ensure that they are being run before any other watchers |
1745 | after the poll. Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers, |
1999 | after the poll. Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers, |
1746 | too) should not activate (\*(L"feed\*(R") events into libev. While libev fully |
2000 | too) should not activate (\*(L"feed\*(R") events into libev. While libev fully |
1747 | supports this, they will be called before other \f(CW\*(C`ev_check\*(C'\fR watchers did |
2001 | supports this, they will be called before other \f(CW\*(C`ev_check\*(C'\fR watchers |
1748 | their job. As \f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other event |
2002 | did their job. As \f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other |
1749 | loops those other event loops might be in an unusable state until their |
2003 | (non-libev) event loops those other event loops might be in an unusable |
1750 | \&\f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to coexist peacefully with |
2004 | state until their \f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to |
1751 | others). |
2005 | coexist peacefully with others). |
1752 | .PP |
2006 | .PP |
1753 | \fIWatcher-Specific Functions and Data Members\fR |
2007 | \fIWatcher-Specific Functions and Data Members\fR |
1754 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2008 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1755 | .IP "ev_prepare_init (ev_prepare *, callback)" 4 |
2009 | .IP "ev_prepare_init (ev_prepare *, callback)" 4 |
1756 | .IX Item "ev_prepare_init (ev_prepare *, callback)" |
2010 | .IX Item "ev_prepare_init (ev_prepare *, callback)" |
… | |
… | |
1760 | .PD |
2014 | .PD |
1761 | Initialises and configures the prepare or check watcher \- they have no |
2015 | Initialises and configures the prepare or check watcher \- they have no |
1762 | parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR |
2016 | parameters of any kind. There are \f(CW\*(C`ev_prepare_set\*(C'\fR and \f(CW\*(C`ev_check_set\*(C'\fR |
1763 | macros, but using them is utterly, utterly and completely pointless. |
2017 | macros, but using them is utterly, utterly and completely pointless. |
1764 | .PP |
2018 | .PP |
|
|
2019 | \fIExamples\fR |
|
|
2020 | .IX Subsection "Examples" |
|
|
2021 | .PP |
1765 | There are a number of principal ways to embed other event loops or modules |
2022 | There are a number of principal ways to embed other event loops or modules |
1766 | into libev. Here are some ideas on how to include libadns into libev |
2023 | into libev. Here are some ideas on how to include libadns into libev |
1767 | (there is a Perl module named \f(CW\*(C`EV::ADNS\*(C'\fR that does this, which you could |
2024 | (there is a Perl module named \f(CW\*(C`EV::ADNS\*(C'\fR that does this, which you could |
1768 | use for an actually working example. Another Perl module named \f(CW\*(C`EV::Glib\*(C'\fR |
2025 | use for an actually working example. Another Perl module named \f(CW\*(C`EV::Glib\*(C'\fR |
1769 | embeds a Glib main context into libev, and finally, \f(CW\*(C`Glib::EV\*(C'\fR embeds \s-1EV\s0 |
2026 | embeds a Glib main context into libev, and finally, \f(CW\*(C`Glib::EV\*(C'\fR embeds \s-1EV\s0 |
… | |
… | |
1776 | the callbacks for the IO/timeout watchers might not have been called yet. |
2033 | the callbacks for the IO/timeout watchers might not have been called yet. |
1777 | .PP |
2034 | .PP |
1778 | .Vb 2 |
2035 | .Vb 2 |
1779 | \& static ev_io iow [nfd]; |
2036 | \& static ev_io iow [nfd]; |
1780 | \& static ev_timer tw; |
2037 | \& static ev_timer tw; |
1781 | .Ve |
2038 | \& |
1782 | .PP |
|
|
1783 | .Vb 4 |
|
|
1784 | \& static void |
2039 | \& static void |
1785 | \& io_cb (ev_loop *loop, ev_io *w, int revents) |
2040 | \& io_cb (ev_loop *loop, ev_io *w, int revents) |
1786 | \& { |
2041 | \& { |
1787 | \& } |
2042 | \& } |
1788 | .Ve |
2043 | \& |
1789 | .PP |
|
|
1790 | .Vb 8 |
|
|
1791 | \& // create io watchers for each fd and a timer before blocking |
2044 | \& // create io watchers for each fd and a timer before blocking |
1792 | \& static void |
2045 | \& static void |
1793 | \& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
2046 | \& adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1794 | \& { |
2047 | \& { |
1795 | \& int timeout = 3600000; |
2048 | \& int timeout = 3600000; |
1796 | \& struct pollfd fds [nfd]; |
2049 | \& struct pollfd fds [nfd]; |
1797 | \& // actual code will need to loop here and realloc etc. |
2050 | \& // actual code will need to loop here and realloc etc. |
1798 | \& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
2051 | \& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1799 | .Ve |
2052 | \& |
1800 | .PP |
|
|
1801 | .Vb 3 |
|
|
1802 | \& /* the callback is illegal, but won't be called as we stop during check */ |
2053 | \& /* the callback is illegal, but won\*(Aqt be called as we stop during check */ |
1803 | \& ev_timer_init (&tw, 0, timeout * 1e-3); |
2054 | \& ev_timer_init (&tw, 0, timeout * 1e\-3); |
1804 | \& ev_timer_start (loop, &tw); |
2055 | \& ev_timer_start (loop, &tw); |
1805 | .Ve |
2056 | \& |
1806 | .PP |
|
|
1807 | .Vb 6 |
|
|
1808 | \& // create one ev_io per pollfd |
2057 | \& // create one ev_io per pollfd |
1809 | \& for (int i = 0; i < nfd; ++i) |
2058 | \& for (int i = 0; i < nfd; ++i) |
1810 | \& { |
2059 | \& { |
1811 | \& ev_io_init (iow + i, io_cb, fds [i].fd, |
2060 | \& ev_io_init (iow + i, io_cb, fds [i].fd, |
1812 | \& ((fds [i].events & POLLIN ? EV_READ : 0) |
2061 | \& ((fds [i].events & POLLIN ? EV_READ : 0) |
1813 | \& | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
2062 | \& | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1814 | .Ve |
2063 | \& |
1815 | .PP |
|
|
1816 | .Vb 4 |
|
|
1817 | \& fds [i].revents = 0; |
2064 | \& fds [i].revents = 0; |
1818 | \& ev_io_start (loop, iow + i); |
2065 | \& ev_io_start (loop, iow + i); |
1819 | \& } |
2066 | \& } |
1820 | \& } |
2067 | \& } |
1821 | .Ve |
2068 | \& |
1822 | .PP |
|
|
1823 | .Vb 5 |
|
|
1824 | \& // stop all watchers after blocking |
2069 | \& // stop all watchers after blocking |
1825 | \& static void |
2070 | \& static void |
1826 | \& adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
2071 | \& adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1827 | \& { |
2072 | \& { |
1828 | \& ev_timer_stop (loop, &tw); |
2073 | \& ev_timer_stop (loop, &tw); |
1829 | .Ve |
2074 | \& |
1830 | .PP |
|
|
1831 | .Vb 8 |
|
|
1832 | \& for (int i = 0; i < nfd; ++i) |
2075 | \& for (int i = 0; i < nfd; ++i) |
1833 | \& { |
2076 | \& { |
1834 | \& // set the relevant poll flags |
2077 | \& // set the relevant poll flags |
1835 | \& // could also call adns_processreadable etc. here |
2078 | \& // could also call adns_processreadable etc. here |
1836 | \& struct pollfd *fd = fds + i; |
2079 | \& struct pollfd *fd = fds + i; |
1837 | \& int revents = ev_clear_pending (iow + i); |
2080 | \& int revents = ev_clear_pending (iow + i); |
1838 | \& if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
2081 | \& if (revents & EV_READ ) fd\->revents |= fd\->events & POLLIN; |
1839 | \& if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
2082 | \& if (revents & EV_WRITE) fd\->revents |= fd\->events & POLLOUT; |
1840 | .Ve |
2083 | \& |
1841 | .PP |
|
|
1842 | .Vb 3 |
|
|
1843 | \& // now stop the watcher |
2084 | \& // now stop the watcher |
1844 | \& ev_io_stop (loop, iow + i); |
2085 | \& ev_io_stop (loop, iow + i); |
1845 | \& } |
2086 | \& } |
1846 | .Ve |
2087 | \& |
1847 | .PP |
|
|
1848 | .Vb 2 |
|
|
1849 | \& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
2088 | \& adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
1850 | \& } |
2089 | \& } |
1851 | .Ve |
2090 | .Ve |
1852 | .PP |
2091 | .PP |
1853 | Method 2: This would be just like method 1, but you run \f(CW\*(C`adns_afterpoll\*(C'\fR |
2092 | Method 2: This would be just like method 1, but you run \f(CW\*(C`adns_afterpoll\*(C'\fR |
… | |
… | |
1859 | .PP |
2098 | .PP |
1860 | .Vb 5 |
2099 | .Vb 5 |
1861 | \& static void |
2100 | \& static void |
1862 | \& timer_cb (EV_P_ ev_timer *w, int revents) |
2101 | \& timer_cb (EV_P_ ev_timer *w, int revents) |
1863 | \& { |
2102 | \& { |
1864 | \& adns_state ads = (adns_state)w->data; |
2103 | \& adns_state ads = (adns_state)w\->data; |
1865 | \& update_now (EV_A); |
2104 | \& update_now (EV_A); |
1866 | .Ve |
2105 | \& |
1867 | .PP |
|
|
1868 | .Vb 2 |
|
|
1869 | \& adns_processtimeouts (ads, &tv_now); |
2106 | \& adns_processtimeouts (ads, &tv_now); |
1870 | \& } |
2107 | \& } |
1871 | .Ve |
2108 | \& |
1872 | .PP |
|
|
1873 | .Vb 5 |
|
|
1874 | \& static void |
2109 | \& static void |
1875 | \& io_cb (EV_P_ ev_io *w, int revents) |
2110 | \& io_cb (EV_P_ ev_io *w, int revents) |
1876 | \& { |
2111 | \& { |
1877 | \& adns_state ads = (adns_state)w->data; |
2112 | \& adns_state ads = (adns_state)w\->data; |
1878 | \& update_now (EV_A); |
2113 | \& update_now (EV_A); |
1879 | .Ve |
2114 | \& |
1880 | .PP |
|
|
1881 | .Vb 3 |
|
|
1882 | \& if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now); |
2115 | \& if (revents & EV_READ ) adns_processreadable (ads, w\->fd, &tv_now); |
1883 | \& if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now); |
2116 | \& if (revents & EV_WRITE) adns_processwriteable (ads, w\->fd, &tv_now); |
1884 | \& } |
2117 | \& } |
1885 | .Ve |
2118 | \& |
1886 | .PP |
|
|
1887 | .Vb 1 |
|
|
1888 | \& // do not ever call adns_afterpoll |
2119 | \& // do not ever call adns_afterpoll |
1889 | .Ve |
2120 | .Ve |
1890 | .PP |
2121 | .PP |
1891 | Method 4: Do not use a prepare or check watcher because the module you |
2122 | Method 4: Do not use a prepare or check watcher because the module you |
1892 | want to embed is too inflexible to support it. Instead, youc na override |
2123 | want to embed is too inflexible to support it. Instead, youc na override |
… | |
… | |
1897 | .Vb 4 |
2128 | .Vb 4 |
1898 | \& static gint |
2129 | \& static gint |
1899 | \& event_poll_func (GPollFD *fds, guint nfds, gint timeout) |
2130 | \& event_poll_func (GPollFD *fds, guint nfds, gint timeout) |
1900 | \& { |
2131 | \& { |
1901 | \& int got_events = 0; |
2132 | \& int got_events = 0; |
1902 | .Ve |
2133 | \& |
1903 | .PP |
|
|
1904 | .Vb 2 |
|
|
1905 | \& for (n = 0; n < nfds; ++n) |
2134 | \& for (n = 0; n < nfds; ++n) |
1906 | \& // create/start io watcher that sets the relevant bits in fds[n] and increment got_events |
2135 | \& // create/start io watcher that sets the relevant bits in fds[n] and increment got_events |
1907 | .Ve |
2136 | \& |
1908 | .PP |
|
|
1909 | .Vb 2 |
|
|
1910 | \& if (timeout >= 0) |
2137 | \& if (timeout >= 0) |
1911 | \& // create/start timer |
2138 | \& // create/start timer |
1912 | .Ve |
2139 | \& |
1913 | .PP |
|
|
1914 | .Vb 2 |
|
|
1915 | \& // poll |
2140 | \& // poll |
1916 | \& ev_loop (EV_A_ 0); |
2141 | \& ev_loop (EV_A_ 0); |
1917 | .Ve |
2142 | \& |
1918 | .PP |
|
|
1919 | .Vb 3 |
|
|
1920 | \& // stop timer again |
2143 | \& // stop timer again |
1921 | \& if (timeout >= 0) |
2144 | \& if (timeout >= 0) |
1922 | \& ev_timer_stop (EV_A_ &to); |
2145 | \& ev_timer_stop (EV_A_ &to); |
1923 | .Ve |
2146 | \& |
1924 | .PP |
|
|
1925 | .Vb 3 |
|
|
1926 | \& // stop io watchers again - their callbacks should have set |
2147 | \& // stop io watchers again \- their callbacks should have set |
1927 | \& for (n = 0; n < nfds; ++n) |
2148 | \& for (n = 0; n < nfds; ++n) |
1928 | \& ev_io_stop (EV_A_ iow [n]); |
2149 | \& ev_io_stop (EV_A_ iow [n]); |
1929 | .Ve |
2150 | \& |
1930 | .PP |
|
|
1931 | .Vb 2 |
|
|
1932 | \& return got_events; |
2151 | \& return got_events; |
1933 | \& } |
2152 | \& } |
1934 | .Ve |
2153 | .Ve |
1935 | .ie n .Sh """ev_embed"" \- when one backend isn't enough..." |
2154 | .ie n .Sh """ev_embed"" \- when one backend isn't enough..." |
1936 | .el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..." |
2155 | .el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..." |
1937 | .IX Subsection "ev_embed - when one backend isn't enough..." |
2156 | .IX Subsection "ev_embed - when one backend isn't enough..." |
1938 | This is a rather advanced watcher type that lets you embed one event loop |
2157 | This is a rather advanced watcher type that lets you embed one event loop |
1939 | into another (currently only \f(CW\*(C`ev_io\*(C'\fR events are supported in the embedded |
2158 | into another (currently only \f(CW\*(C`ev_io\*(C'\fR events are supported in the embedded |
1940 | loop, other types of watchers might be handled in a delayed or incorrect |
2159 | loop, other types of watchers might be handled in a delayed or incorrect |
1941 | fashion and must not be used). (See portability notes, below). |
2160 | fashion and must not be used). |
1942 | .PP |
2161 | .PP |
1943 | There are primarily two reasons you would want that: work around bugs and |
2162 | There are primarily two reasons you would want that: work around bugs and |
1944 | prioritise I/O. |
2163 | prioritise I/O. |
1945 | .PP |
2164 | .PP |
1946 | As an example for a bug workaround, the kqueue backend might only support |
2165 | As an example for a bug workaround, the kqueue backend might only support |
… | |
… | |
1980 | portable one. |
2199 | portable one. |
1981 | .PP |
2200 | .PP |
1982 | So when you want to use this feature you will always have to be prepared |
2201 | So when you want to use this feature you will always have to be prepared |
1983 | that you cannot get an embeddable loop. The recommended way to get around |
2202 | that you cannot get an embeddable loop. The recommended way to get around |
1984 | this is to have a separate variables for your embeddable loop, try to |
2203 | this is to have a separate variables for your embeddable loop, try to |
1985 | create it, and if that fails, use the normal loop for everything: |
2204 | create it, and if that fails, use the normal loop for everything. |
1986 | .PP |
|
|
1987 | .Vb 3 |
|
|
1988 | \& struct ev_loop *loop_hi = ev_default_init (0); |
|
|
1989 | \& struct ev_loop *loop_lo = 0; |
|
|
1990 | \& struct ev_embed embed; |
|
|
1991 | .Ve |
|
|
1992 | .PP |
|
|
1993 | .Vb 5 |
|
|
1994 | \& // see if there is a chance of getting one that works |
|
|
1995 | \& // (remember that a flags value of 0 means autodetection) |
|
|
1996 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
|
|
1997 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
|
|
1998 | \& : 0; |
|
|
1999 | .Ve |
|
|
2000 | .PP |
|
|
2001 | .Vb 8 |
|
|
2002 | \& // if we got one, then embed it, otherwise default to loop_hi |
|
|
2003 | \& if (loop_lo) |
|
|
2004 | \& { |
|
|
2005 | \& ev_embed_init (&embed, 0, loop_lo); |
|
|
2006 | \& ev_embed_start (loop_hi, &embed); |
|
|
2007 | \& } |
|
|
2008 | \& else |
|
|
2009 | \& loop_lo = loop_hi; |
|
|
2010 | .Ve |
|
|
2011 | .Sh "Portability notes" |
|
|
2012 | .IX Subsection "Portability notes" |
|
|
2013 | Kqueue is nominally embeddable, but this is broken on all BSDs that I |
|
|
2014 | tried, in various ways. Usually the embedded event loop will simply never |
|
|
2015 | receive events, sometimes it will only trigger a few times, sometimes in a |
|
|
2016 | loop. Epoll is also nominally embeddable, but many Linux kernel versions |
|
|
2017 | will always eport the epoll fd as ready, even when no events are pending. |
|
|
2018 | .PP |
|
|
2019 | While libev allows embedding these backends (they are contained in |
|
|
2020 | \&\f(CW\*(C`ev_embeddable_backends ()\*(C'\fR), take extreme care that it will actually |
|
|
2021 | work. |
|
|
2022 | .PP |
|
|
2023 | When in doubt, create a dynamic event loop forced to use sockets (this |
|
|
2024 | usually works) and possibly another thread and a pipe or so to report to |
|
|
2025 | your main event loop. |
|
|
2026 | .PP |
2205 | .PP |
2027 | \fIWatcher-Specific Functions and Data Members\fR |
2206 | \fIWatcher-Specific Functions and Data Members\fR |
2028 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2207 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2029 | .IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
2208 | .IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
2030 | .IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" |
2209 | .IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" |
… | |
… | |
2043 | similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most |
2222 | similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most |
2044 | apropriate way for embedded loops. |
2223 | apropriate way for embedded loops. |
2045 | .IP "struct ev_loop *other [read\-only]" 4 |
2224 | .IP "struct ev_loop *other [read\-only]" 4 |
2046 | .IX Item "struct ev_loop *other [read-only]" |
2225 | .IX Item "struct ev_loop *other [read-only]" |
2047 | The embedded event loop. |
2226 | The embedded event loop. |
|
|
2227 | .PP |
|
|
2228 | \fIExamples\fR |
|
|
2229 | .IX Subsection "Examples" |
|
|
2230 | .PP |
|
|
2231 | Example: Try to get an embeddable event loop and embed it into the default |
|
|
2232 | event loop. If that is not possible, use the default loop. The default |
|
|
2233 | loop is stored in \f(CW\*(C`loop_hi\*(C'\fR, while the mebeddable loop is stored in |
|
|
2234 | \&\f(CW\*(C`loop_lo\*(C'\fR (which is \f(CW\*(C`loop_hi\*(C'\fR in the acse no embeddable loop can be |
|
|
2235 | used). |
|
|
2236 | .PP |
|
|
2237 | .Vb 3 |
|
|
2238 | \& struct ev_loop *loop_hi = ev_default_init (0); |
|
|
2239 | \& struct ev_loop *loop_lo = 0; |
|
|
2240 | \& struct ev_embed embed; |
|
|
2241 | \& |
|
|
2242 | \& // see if there is a chance of getting one that works |
|
|
2243 | \& // (remember that a flags value of 0 means autodetection) |
|
|
2244 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
|
|
2245 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
|
|
2246 | \& : 0; |
|
|
2247 | \& |
|
|
2248 | \& // if we got one, then embed it, otherwise default to loop_hi |
|
|
2249 | \& if (loop_lo) |
|
|
2250 | \& { |
|
|
2251 | \& ev_embed_init (&embed, 0, loop_lo); |
|
|
2252 | \& ev_embed_start (loop_hi, &embed); |
|
|
2253 | \& } |
|
|
2254 | \& else |
|
|
2255 | \& loop_lo = loop_hi; |
|
|
2256 | .Ve |
|
|
2257 | .PP |
|
|
2258 | Example: Check if kqueue is available but not recommended and create |
|
|
2259 | a kqueue backend for use with sockets (which usually work with any |
|
|
2260 | kqueue implementation). Store the kqueue/socket\-only event loop in |
|
|
2261 | \&\f(CW\*(C`loop_socket\*(C'\fR. (One might optionally use \f(CW\*(C`EVFLAG_NOENV\*(C'\fR, too). |
|
|
2262 | .PP |
|
|
2263 | .Vb 3 |
|
|
2264 | \& struct ev_loop *loop = ev_default_init (0); |
|
|
2265 | \& struct ev_loop *loop_socket = 0; |
|
|
2266 | \& struct ev_embed embed; |
|
|
2267 | \& |
|
|
2268 | \& if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
|
|
2269 | \& if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
|
|
2270 | \& { |
|
|
2271 | \& ev_embed_init (&embed, 0, loop_socket); |
|
|
2272 | \& ev_embed_start (loop, &embed); |
|
|
2273 | \& } |
|
|
2274 | \& |
|
|
2275 | \& if (!loop_socket) |
|
|
2276 | \& loop_socket = loop; |
|
|
2277 | \& |
|
|
2278 | \& // now use loop_socket for all sockets, and loop for everything else |
|
|
2279 | .Ve |
2048 | .ie n .Sh """ev_fork"" \- the audacity to resume the event loop after a fork" |
2280 | .ie n .Sh """ev_fork"" \- the audacity to resume the event loop after a fork" |
2049 | .el .Sh "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
2281 | .el .Sh "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
2050 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
2282 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
2051 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
2283 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
2052 | whoever is a good citizen cared to tell libev about it by calling |
2284 | whoever is a good citizen cared to tell libev about it by calling |
… | |
… | |
2061 | .IP "ev_fork_init (ev_signal *, callback)" 4 |
2293 | .IP "ev_fork_init (ev_signal *, callback)" 4 |
2062 | .IX Item "ev_fork_init (ev_signal *, callback)" |
2294 | .IX Item "ev_fork_init (ev_signal *, callback)" |
2063 | Initialises and configures the fork watcher \- it has no parameters of any |
2295 | Initialises and configures the fork watcher \- it has no parameters of any |
2064 | kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless, |
2296 | kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless, |
2065 | believe me. |
2297 | believe me. |
|
|
2298 | .ie n .Sh """ev_async"" \- how to wake up another event loop" |
|
|
2299 | .el .Sh "\f(CWev_async\fP \- how to wake up another event loop" |
|
|
2300 | .IX Subsection "ev_async - how to wake up another event loop" |
|
|
2301 | In general, you cannot use an \f(CW\*(C`ev_loop\*(C'\fR from multiple threads or other |
|
|
2302 | asynchronous sources such as signal handlers (as opposed to multiple event |
|
|
2303 | loops \- those are of course safe to use in different threads). |
|
|
2304 | .PP |
|
|
2305 | Sometimes, however, you need to wake up another event loop you do not |
|
|
2306 | control, for example because it belongs to another thread. This is what |
|
|
2307 | \&\f(CW\*(C`ev_async\*(C'\fR watchers do: as long as the \f(CW\*(C`ev_async\*(C'\fR watcher is active, you |
|
|
2308 | can signal it by calling \f(CW\*(C`ev_async_send\*(C'\fR, which is thread\- and signal |
|
|
2309 | safe. |
|
|
2310 | .PP |
|
|
2311 | This functionality is very similar to \f(CW\*(C`ev_signal\*(C'\fR watchers, as signals, |
|
|
2312 | too, are asynchronous in nature, and signals, too, will be compressed |
|
|
2313 | (i.e. the number of callback invocations may be less than the number of |
|
|
2314 | \&\f(CW\*(C`ev_async_sent\*(C'\fR calls). |
|
|
2315 | .PP |
|
|
2316 | Unlike \f(CW\*(C`ev_signal\*(C'\fR watchers, \f(CW\*(C`ev_async\*(C'\fR works with any event loop, not |
|
|
2317 | just the default loop. |
|
|
2318 | .PP |
|
|
2319 | \fIQueueing\fR |
|
|
2320 | .IX Subsection "Queueing" |
|
|
2321 | .PP |
|
|
2322 | \&\f(CW\*(C`ev_async\*(C'\fR does not support queueing of data in any way. The reason |
|
|
2323 | is that the author does not know of a simple (or any) algorithm for a |
|
|
2324 | multiple-writer-single-reader queue that works in all cases and doesn't |
|
|
2325 | need elaborate support such as pthreads. |
|
|
2326 | .PP |
|
|
2327 | That means that if you want to queue data, you have to provide your own |
|
|
2328 | queue. But at least I can tell you would implement locking around your |
|
|
2329 | queue: |
|
|
2330 | .IP "queueing from a signal handler context" 4 |
|
|
2331 | .IX Item "queueing from a signal handler context" |
|
|
2332 | To implement race-free queueing, you simply add to the queue in the signal |
|
|
2333 | handler but you block the signal handler in the watcher callback. Here is an example that does that for |
|
|
2334 | some fictitiuous \s-1SIGUSR1\s0 handler: |
|
|
2335 | .Sp |
|
|
2336 | .Vb 1 |
|
|
2337 | \& static ev_async mysig; |
|
|
2338 | \& |
|
|
2339 | \& static void |
|
|
2340 | \& sigusr1_handler (void) |
|
|
2341 | \& { |
|
|
2342 | \& sometype data; |
|
|
2343 | \& |
|
|
2344 | \& // no locking etc. |
|
|
2345 | \& queue_put (data); |
|
|
2346 | \& ev_async_send (EV_DEFAULT_ &mysig); |
|
|
2347 | \& } |
|
|
2348 | \& |
|
|
2349 | \& static void |
|
|
2350 | \& mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
2351 | \& { |
|
|
2352 | \& sometype data; |
|
|
2353 | \& sigset_t block, prev; |
|
|
2354 | \& |
|
|
2355 | \& sigemptyset (&block); |
|
|
2356 | \& sigaddset (&block, SIGUSR1); |
|
|
2357 | \& sigprocmask (SIG_BLOCK, &block, &prev); |
|
|
2358 | \& |
|
|
2359 | \& while (queue_get (&data)) |
|
|
2360 | \& process (data); |
|
|
2361 | \& |
|
|
2362 | \& if (sigismember (&prev, SIGUSR1) |
|
|
2363 | \& sigprocmask (SIG_UNBLOCK, &block, 0); |
|
|
2364 | \& } |
|
|
2365 | .Ve |
|
|
2366 | .Sp |
|
|
2367 | (Note: pthreads in theory requires you to use \f(CW\*(C`pthread_setmask\*(C'\fR |
|
|
2368 | instead of \f(CW\*(C`sigprocmask\*(C'\fR when you use threads, but libev doesn't do it |
|
|
2369 | either...). |
|
|
2370 | .IP "queueing from a thread context" 4 |
|
|
2371 | .IX Item "queueing from a thread context" |
|
|
2372 | The strategy for threads is different, as you cannot (easily) block |
|
|
2373 | threads but you can easily preempt them, so to queue safely you need to |
|
|
2374 | employ a traditional mutex lock, such as in this pthread example: |
|
|
2375 | .Sp |
|
|
2376 | .Vb 2 |
|
|
2377 | \& static ev_async mysig; |
|
|
2378 | \& static pthread_mutex_t mymutex = PTHREAD_MUTEX_INITIALIZER; |
|
|
2379 | \& |
|
|
2380 | \& static void |
|
|
2381 | \& otherthread (void) |
|
|
2382 | \& { |
|
|
2383 | \& // only need to lock the actual queueing operation |
|
|
2384 | \& pthread_mutex_lock (&mymutex); |
|
|
2385 | \& queue_put (data); |
|
|
2386 | \& pthread_mutex_unlock (&mymutex); |
|
|
2387 | \& |
|
|
2388 | \& ev_async_send (EV_DEFAULT_ &mysig); |
|
|
2389 | \& } |
|
|
2390 | \& |
|
|
2391 | \& static void |
|
|
2392 | \& mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
2393 | \& { |
|
|
2394 | \& pthread_mutex_lock (&mymutex); |
|
|
2395 | \& |
|
|
2396 | \& while (queue_get (&data)) |
|
|
2397 | \& process (data); |
|
|
2398 | \& |
|
|
2399 | \& pthread_mutex_unlock (&mymutex); |
|
|
2400 | \& } |
|
|
2401 | .Ve |
|
|
2402 | .PP |
|
|
2403 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
2404 | .IX Subsection "Watcher-Specific Functions and Data Members" |
|
|
2405 | .IP "ev_async_init (ev_async *, callback)" 4 |
|
|
2406 | .IX Item "ev_async_init (ev_async *, callback)" |
|
|
2407 | Initialises and configures the async watcher \- it has no parameters of any |
|
|
2408 | kind. There is a \f(CW\*(C`ev_asynd_set\*(C'\fR macro, but using it is utterly pointless, |
|
|
2409 | believe me. |
|
|
2410 | .IP "ev_async_send (loop, ev_async *)" 4 |
|
|
2411 | .IX Item "ev_async_send (loop, ev_async *)" |
|
|
2412 | Sends/signals/activates the given \f(CW\*(C`ev_async\*(C'\fR watcher, that is, feeds |
|
|
2413 | an \f(CW\*(C`EV_ASYNC\*(C'\fR event on the watcher into the event loop. Unlike |
|
|
2414 | \&\f(CW\*(C`ev_feed_event\*(C'\fR, this call is safe to do in other threads, signal or |
|
|
2415 | similar contexts (see the dicusssion of \f(CW\*(C`EV_ATOMIC_T\*(C'\fR in the embedding |
|
|
2416 | section below on what exactly this means). |
|
|
2417 | .Sp |
|
|
2418 | This call incurs the overhead of a syscall only once per loop iteration, |
|
|
2419 | so while the overhead might be noticable, it doesn't apply to repeated |
|
|
2420 | calls to \f(CW\*(C`ev_async_send\*(C'\fR. |
|
|
2421 | .IP "bool = ev_async_pending (ev_async *)" 4 |
|
|
2422 | .IX Item "bool = ev_async_pending (ev_async *)" |
|
|
2423 | Returns a non-zero value when \f(CW\*(C`ev_async_send\*(C'\fR has been called on the |
|
|
2424 | watcher but the event has not yet been processed (or even noted) by the |
|
|
2425 | event loop. |
|
|
2426 | .Sp |
|
|
2427 | \&\f(CW\*(C`ev_async_send\*(C'\fR sets a flag in the watcher and wakes up the loop. When |
|
|
2428 | the loop iterates next and checks for the watcher to have become active, |
|
|
2429 | it will reset the flag again. \f(CW\*(C`ev_async_pending\*(C'\fR can be used to very |
|
|
2430 | quickly check wether invoking the loop might be a good idea. |
|
|
2431 | .Sp |
|
|
2432 | Not that this does \fInot\fR check wether the watcher itself is pending, only |
|
|
2433 | wether it has been requested to make this watcher pending. |
2066 | .SH "OTHER FUNCTIONS" |
2434 | .SH "OTHER FUNCTIONS" |
2067 | .IX Header "OTHER FUNCTIONS" |
2435 | .IX Header "OTHER FUNCTIONS" |
2068 | There are some other functions of possible interest. Described. Here. Now. |
2436 | There are some other functions of possible interest. Described. Here. Now. |
2069 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 |
2437 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 |
2070 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" |
2438 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" |
… | |
… | |
2094 | \& if (revents & EV_TIMEOUT) |
2462 | \& if (revents & EV_TIMEOUT) |
2095 | \& /* doh, nothing entered */; |
2463 | \& /* doh, nothing entered */; |
2096 | \& else if (revents & EV_READ) |
2464 | \& else if (revents & EV_READ) |
2097 | \& /* stdin might have data for us, joy! */; |
2465 | \& /* stdin might have data for us, joy! */; |
2098 | \& } |
2466 | \& } |
2099 | .Ve |
2467 | \& |
2100 | .Sp |
|
|
2101 | .Vb 1 |
|
|
2102 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
2468 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
2103 | .Ve |
2469 | .Ve |
2104 | .IP "ev_feed_event (ev_loop *, watcher *, int revents)" 4 |
2470 | .IP "ev_feed_event (ev_loop *, watcher *, int revents)" 4 |
2105 | .IX Item "ev_feed_event (ev_loop *, watcher *, int revents)" |
2471 | .IX Item "ev_feed_event (ev_loop *, watcher *, int revents)" |
2106 | Feeds the given event set into the event loop, as if the specified event |
2472 | Feeds the given event set into the event loop, as if the specified event |
… | |
… | |
2116 | loop!). |
2482 | loop!). |
2117 | .SH "LIBEVENT EMULATION" |
2483 | .SH "LIBEVENT EMULATION" |
2118 | .IX Header "LIBEVENT EMULATION" |
2484 | .IX Header "LIBEVENT EMULATION" |
2119 | Libev offers a compatibility emulation layer for libevent. It cannot |
2485 | Libev offers a compatibility emulation layer for libevent. It cannot |
2120 | emulate the internals of libevent, so here are some usage hints: |
2486 | emulate the internals of libevent, so here are some usage hints: |
|
|
2487 | .IP "\(bu" 4 |
2121 | .IP "* Use it by including <event.h>, as usual." 4 |
2488 | Use it by including <event.h>, as usual. |
2122 | .IX Item "Use it by including <event.h>, as usual." |
2489 | .IP "\(bu" 4 |
2123 | .PD 0 |
2490 | The following members are fully supported: ev_base, ev_callback, |
2124 | .IP "* The following members are fully supported: ev_base, ev_callback, ev_arg, ev_fd, ev_res, ev_events." 4 |
2491 | ev_arg, ev_fd, ev_res, ev_events. |
2125 | .IX Item "The following members are fully supported: ev_base, ev_callback, ev_arg, ev_fd, ev_res, ev_events." |
2492 | .IP "\(bu" 4 |
2126 | .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 |
2493 | Avoid using ev_flags and the EVLIST_*\-macros, while it is |
2127 | .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)." |
2494 | maintained by libev, it does not work exactly the same way as in libevent (consider |
2128 | .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 |
2495 | it a private \s-1API\s0). |
2129 | .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." |
2496 | .IP "\(bu" 4 |
|
|
2497 | Priorities are not currently supported. Initialising priorities |
|
|
2498 | will fail and all watchers will have the same priority, even though there |
|
|
2499 | is an ev_pri field. |
|
|
2500 | .IP "\(bu" 4 |
2130 | .IP "* Other members are not supported." 4 |
2501 | Other members are not supported. |
2131 | .IX Item "Other members are not supported." |
2502 | .IP "\(bu" 4 |
2132 | .IP "* The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need to use the libev header file and library." 4 |
2503 | The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need |
2133 | .IX Item "The libev emulation is not ABI compatible to libevent, you need to use the libev header file and library." |
2504 | to use the libev header file and library. |
2134 | .PD |
|
|
2135 | .SH "\*(C+ SUPPORT" |
2505 | .SH "\*(C+ SUPPORT" |
2136 | .IX Header " SUPPORT" |
2506 | .IX Header " SUPPORT" |
2137 | Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow |
2507 | Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow |
2138 | you to use some convinience methods to start/stop watchers and also change |
2508 | you to use some convinience methods to start/stop watchers and also change |
2139 | the callback model to a model using method callbacks on objects. |
2509 | the callback model to a model using method callbacks on objects. |
… | |
… | |
2219 | .Vb 4 |
2589 | .Vb 4 |
2220 | \& struct myclass |
2590 | \& struct myclass |
2221 | \& { |
2591 | \& { |
2222 | \& void io_cb (ev::io &w, int revents) { } |
2592 | \& void io_cb (ev::io &w, int revents) { } |
2223 | \& } |
2593 | \& } |
2224 | .Ve |
2594 | \& |
2225 | .Sp |
|
|
2226 | .Vb 3 |
|
|
2227 | \& myclass obj; |
2595 | \& myclass obj; |
2228 | \& ev::io iow; |
2596 | \& ev::io iow; |
2229 | \& iow.set <myclass, &myclass::io_cb> (&obj); |
2597 | \& iow.set <myclass, &myclass::io_cb> (&obj); |
2230 | .Ve |
2598 | .Ve |
2231 | .IP "w\->set<function> (void *data = 0)" 4 |
2599 | .IP "w\->set<function> (void *data = 0)" 4 |
… | |
… | |
2282 | the constructor. |
2650 | the constructor. |
2283 | .PP |
2651 | .PP |
2284 | .Vb 4 |
2652 | .Vb 4 |
2285 | \& class myclass |
2653 | \& class myclass |
2286 | \& { |
2654 | \& { |
2287 | \& ev_io io; void io_cb (ev::io &w, int revents); |
2655 | \& ev::io io; void io_cb (ev::io &w, int revents); |
2288 | \& ev_idle idle void idle_cb (ev::idle &w, int revents); |
2656 | \& ev:idle idle void idle_cb (ev::idle &w, int revents); |
2289 | .Ve |
2657 | \& |
2290 | .PP |
|
|
2291 | .Vb 2 |
|
|
2292 | \& myclass (); |
2658 | \& myclass (int fd) |
2293 | \& } |
|
|
2294 | .Ve |
|
|
2295 | .PP |
|
|
2296 | .Vb 4 |
|
|
2297 | \& myclass::myclass (int fd) |
|
|
2298 | \& { |
2659 | \& { |
2299 | \& io .set <myclass, &myclass::io_cb > (this); |
2660 | \& io .set <myclass, &myclass::io_cb > (this); |
2300 | \& idle.set <myclass, &myclass::idle_cb> (this); |
2661 | \& idle.set <myclass, &myclass::idle_cb> (this); |
2301 | .Ve |
2662 | \& |
2302 | .PP |
|
|
2303 | .Vb 2 |
|
|
2304 | \& io.start (fd, ev::READ); |
2663 | \& io.start (fd, ev::READ); |
|
|
2664 | \& } |
2305 | \& } |
2665 | \& }; |
2306 | .Ve |
2666 | .Ve |
|
|
2667 | .SH "OTHER LANGUAGE BINDINGS" |
|
|
2668 | .IX Header "OTHER LANGUAGE BINDINGS" |
|
|
2669 | Libev does not offer other language bindings itself, but bindings for a |
|
|
2670 | numbe rof languages exist in the form of third-party packages. If you know |
|
|
2671 | any interesting language binding in addition to the ones listed here, drop |
|
|
2672 | me a note. |
|
|
2673 | .IP "Perl" 4 |
|
|
2674 | .IX Item "Perl" |
|
|
2675 | The \s-1EV\s0 module implements the full libev \s-1API\s0 and is actually used to test |
|
|
2676 | libev. \s-1EV\s0 is developed together with libev. Apart from the \s-1EV\s0 core module, |
|
|
2677 | there are additional modules that implement libev-compatible interfaces |
|
|
2678 | to \f(CW\*(C`libadns\*(C'\fR (\f(CW\*(C`EV::ADNS\*(C'\fR), \f(CW\*(C`Net::SNMP\*(C'\fR (\f(CW\*(C`Net::SNMP::EV\*(C'\fR) and the |
|
|
2679 | \&\f(CW\*(C`libglib\*(C'\fR event core (\f(CW\*(C`Glib::EV\*(C'\fR and \f(CW\*(C`EV::Glib\*(C'\fR). |
|
|
2680 | .Sp |
|
|
2681 | It can be found and installed via \s-1CPAN\s0, its homepage is found at |
|
|
2682 | <http://software.schmorp.de/pkg/EV>. |
|
|
2683 | .IP "Ruby" 4 |
|
|
2684 | .IX Item "Ruby" |
|
|
2685 | Tony Arcieri has written a ruby extension that offers access to a subset |
|
|
2686 | of the libev \s-1API\s0 and adds filehandle abstractions, asynchronous \s-1DNS\s0 and |
|
|
2687 | more on top of it. It can be found via gem servers. Its homepage is at |
|
|
2688 | <http://rev.rubyforge.org/>. |
|
|
2689 | .IP "D" 4 |
|
|
2690 | .IX Item "D" |
|
|
2691 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
|
|
2692 | be found at <http://git.llucax.com.ar/?p=software/ev.d.git;a=summary>. |
2307 | .SH "MACRO MAGIC" |
2693 | .SH "MACRO MAGIC" |
2308 | .IX Header "MACRO MAGIC" |
2694 | .IX Header "MACRO MAGIC" |
2309 | Libev can be compiled with a variety of options, the most fundamantal |
2695 | Libev can be compiled with a variety of options, the most fundamantal |
2310 | of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) |
2696 | of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) |
2311 | functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
2697 | functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
… | |
… | |
2335 | \&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example: |
2721 | \&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example: |
2336 | .Sp |
2722 | .Sp |
2337 | .Vb 2 |
2723 | .Vb 2 |
2338 | \& // this is how ev_unref is being declared |
2724 | \& // this is how ev_unref is being declared |
2339 | \& static void ev_unref (EV_P); |
2725 | \& static void ev_unref (EV_P); |
2340 | .Ve |
2726 | \& |
2341 | .Sp |
|
|
2342 | .Vb 2 |
|
|
2343 | \& // this is how you can declare your typical callback |
2727 | \& // this is how you can declare your typical callback |
2344 | \& static void cb (EV_P_ ev_timer *w, int revents) |
2728 | \& static void cb (EV_P_ ev_timer *w, int revents) |
2345 | .Ve |
2729 | .Ve |
2346 | .Sp |
2730 | .Sp |
2347 | It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite |
2731 | It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite |
… | |
… | |
2360 | \& static void |
2744 | \& static void |
2361 | \& check_cb (EV_P_ ev_timer *w, int revents) |
2745 | \& check_cb (EV_P_ ev_timer *w, int revents) |
2362 | \& { |
2746 | \& { |
2363 | \& ev_check_stop (EV_A_ w); |
2747 | \& ev_check_stop (EV_A_ w); |
2364 | \& } |
2748 | \& } |
2365 | .Ve |
2749 | \& |
2366 | .PP |
|
|
2367 | .Vb 4 |
|
|
2368 | \& ev_check check; |
2750 | \& ev_check check; |
2369 | \& ev_check_init (&check, check_cb); |
2751 | \& ev_check_init (&check, check_cb); |
2370 | \& ev_check_start (EV_DEFAULT_ &check); |
2752 | \& ev_check_start (EV_DEFAULT_ &check); |
2371 | \& ev_loop (EV_DEFAULT_ 0); |
2753 | \& ev_loop (EV_DEFAULT_ 0); |
2372 | .Ve |
2754 | .Ve |
2373 | .SH "EMBEDDING" |
2755 | .SH "EMBEDDING" |
2374 | .IX Header "EMBEDDING" |
2756 | .IX Header "EMBEDDING" |
2375 | Libev can (and often is) directly embedded into host |
2757 | Libev can (and often is) directly embedded into host |
2376 | applications. Examples of applications that embed it include the Deliantra |
2758 | applications. Examples of applications that embed it include the Deliantra |
2377 | Game Server, the \s-1EV\s0 perl module, the \s-1GNU\s0 Virtual Private Ethernet (gvpe) |
2759 | Game Server, the \s-1EV\s0 perl module, the \s-1GNU\s0 Virtual Private Ethernet (gvpe) |
2378 | and rxvt\-unicode. |
2760 | and rxvt-unicode. |
2379 | .PP |
2761 | .PP |
2380 | The goal is to enable you to just copy the necessary files into your |
2762 | The goal is to enable you to just copy the necessary files into your |
2381 | source directory without having to change even a single line in them, so |
2763 | source directory without having to change even a single line in them, so |
2382 | you can easily upgrade by simply copying (or having a checked-out copy of |
2764 | you can easily upgrade by simply copying (or having a checked-out copy of |
2383 | libev somewhere in your source tree). |
2765 | libev somewhere in your source tree). |
… | |
… | |
2418 | .Vb 4 |
2800 | .Vb 4 |
2419 | \& ev.h |
2801 | \& ev.h |
2420 | \& ev.c |
2802 | \& ev.c |
2421 | \& ev_vars.h |
2803 | \& ev_vars.h |
2422 | \& ev_wrap.h |
2804 | \& ev_wrap.h |
2423 | .Ve |
2805 | \& |
2424 | .PP |
|
|
2425 | .Vb 1 |
|
|
2426 | \& ev_win32.c required on win32 platforms only |
2806 | \& ev_win32.c required on win32 platforms only |
2427 | .Ve |
2807 | \& |
2428 | .PP |
|
|
2429 | .Vb 5 |
|
|
2430 | \& ev_select.c only when select backend is enabled (which is enabled by default) |
2808 | \& ev_select.c only when select backend is enabled (which is enabled by default) |
2431 | \& ev_poll.c only when poll backend is enabled (disabled by default) |
2809 | \& ev_poll.c only when poll backend is enabled (disabled by default) |
2432 | \& ev_epoll.c only when the epoll backend is enabled (disabled by default) |
2810 | \& ev_epoll.c only when the epoll backend is enabled (disabled by default) |
2433 | \& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
2811 | \& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
2434 | \& ev_port.c only when the solaris port backend is enabled (disabled by default) |
2812 | \& ev_port.c only when the solaris port backend is enabled (disabled by default) |
… | |
… | |
2501 | realtime clock option at compiletime (and assume its availability at |
2879 | realtime clock option at compiletime (and assume its availability at |
2502 | runtime if successful). Otherwise no use of the realtime clock option will |
2880 | runtime if successful). Otherwise no use of the realtime clock option will |
2503 | be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR by \f(CW\*(C`clock_get |
2881 | be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR by \f(CW\*(C`clock_get |
2504 | (CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect correctness. See the |
2882 | (CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect correctness. See the |
2505 | note about libraries in the description of \f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though. |
2883 | note about libraries in the description of \f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though. |
|
|
2884 | .IP "\s-1EV_USE_NANOSLEEP\s0" 4 |
|
|
2885 | .IX Item "EV_USE_NANOSLEEP" |
|
|
2886 | If defined to be \f(CW1\fR, libev will assume that \f(CW\*(C`nanosleep ()\*(C'\fR is available |
|
|
2887 | and will use it for delays. Otherwise it will use \f(CW\*(C`select ()\*(C'\fR. |
2506 | .IP "\s-1EV_USE_SELECT\s0" 4 |
2888 | .IP "\s-1EV_USE_SELECT\s0" 4 |
2507 | .IX Item "EV_USE_SELECT" |
2889 | .IX Item "EV_USE_SELECT" |
2508 | If undefined or defined to be \f(CW1\fR, libev will compile in support for the |
2890 | If undefined or defined to be \f(CW1\fR, libev will compile in support for the |
2509 | \&\f(CW\*(C`select\*(C'\fR(2) backend. No attempt at autodetection will be done: if no |
2891 | \&\f(CW\*(C`select\*(C'\fR(2) backend. No attempt at autodetection will be done: if no |
2510 | other method takes over, select will be it. Otherwise the select backend |
2892 | other method takes over, select will be it. Otherwise the select backend |
… | |
… | |
2525 | wants osf handles on win32 (this is the case when the select to |
2907 | wants osf handles on win32 (this is the case when the select to |
2526 | be used is the winsock select). This means that it will call |
2908 | be used is the winsock select). This means that it will call |
2527 | \&\f(CW\*(C`_get_osfhandle\*(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise, |
2909 | \&\f(CW\*(C`_get_osfhandle\*(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise, |
2528 | it is assumed that all these functions actually work on fds, even |
2910 | it is assumed that all these functions actually work on fds, even |
2529 | on win32. Should not be defined on non\-win32 platforms. |
2911 | on win32. Should not be defined on non\-win32 platforms. |
|
|
2912 | .IP "\s-1EV_FD_TO_WIN32_HANDLE\s0" 4 |
|
|
2913 | .IX Item "EV_FD_TO_WIN32_HANDLE" |
|
|
2914 | If \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR is enabled, then libev needs a way to map |
|
|
2915 | file descriptors to socket handles. When not defining this symbol (the |
|
|
2916 | default), then libev will call \f(CW\*(C`_get_osfhandle\*(C'\fR, which is usually |
|
|
2917 | correct. In some cases, programs use their own file descriptor management, |
|
|
2918 | in which case they can provide this function to map fds to socket handles. |
2530 | .IP "\s-1EV_USE_POLL\s0" 4 |
2919 | .IP "\s-1EV_USE_POLL\s0" 4 |
2531 | .IX Item "EV_USE_POLL" |
2920 | .IX Item "EV_USE_POLL" |
2532 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
2921 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
2533 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
2922 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
2534 | takes precedence over select. |
2923 | takes precedence over select. |
… | |
… | |
2561 | .IP "\s-1EV_USE_INOTIFY\s0" 4 |
2950 | .IP "\s-1EV_USE_INOTIFY\s0" 4 |
2562 | .IX Item "EV_USE_INOTIFY" |
2951 | .IX Item "EV_USE_INOTIFY" |
2563 | If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify |
2952 | If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify |
2564 | interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will |
2953 | interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will |
2565 | be detected at runtime. |
2954 | be detected at runtime. |
|
|
2955 | .IP "\s-1EV_ATOMIC_T\s0" 4 |
|
|
2956 | .IX Item "EV_ATOMIC_T" |
|
|
2957 | Libev requires an integer type (suitable for storing \f(CW0\fR or \f(CW1\fR) whose |
|
|
2958 | access is atomic with respect to other threads or signal contexts. No such |
|
|
2959 | type is easily found in the C language, so you can provide your own type |
|
|
2960 | that you know is safe for your purposes. It is used both for signal handler \*(L"locking\*(R" |
|
|
2961 | as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR watchers. |
|
|
2962 | .Sp |
|
|
2963 | In the absense of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR |
|
|
2964 | (from \fIsignal.h\fR), which is usually good enough on most platforms. |
2566 | .IP "\s-1EV_H\s0" 4 |
2965 | .IP "\s-1EV_H\s0" 4 |
2567 | .IX Item "EV_H" |
2966 | .IX Item "EV_H" |
2568 | The name of the \fIev.h\fR header file used to include it. The default if |
2967 | The name of the \fIev.h\fR header file used to include it. The default if |
2569 | undefined is \f(CW\*(C`<ev.h>\*(C'\fR in \fIevent.h\fR and \f(CW"ev.h"\fR in \fIev.c\fR. This |
2968 | undefined is \f(CW"ev.h"\fR in \fIevent.h\fR, \fIev.c\fR and \fIev++.h\fR. This can be |
2570 | can be used to virtually rename the \fIev.h\fR header file in case of conflicts. |
2969 | used to virtually rename the \fIev.h\fR header file in case of conflicts. |
2571 | .IP "\s-1EV_CONFIG_H\s0" 4 |
2970 | .IP "\s-1EV_CONFIG_H\s0" 4 |
2572 | .IX Item "EV_CONFIG_H" |
2971 | .IX Item "EV_CONFIG_H" |
2573 | If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override |
2972 | If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override |
2574 | \&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to |
2973 | \&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to |
2575 | \&\f(CW\*(C`EV_H\*(C'\fR, above. |
2974 | \&\f(CW\*(C`EV_H\*(C'\fR, above. |
2576 | .IP "\s-1EV_EVENT_H\s0" 4 |
2975 | .IP "\s-1EV_EVENT_H\s0" 4 |
2577 | .IX Item "EV_EVENT_H" |
2976 | .IX Item "EV_EVENT_H" |
2578 | Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea |
2977 | Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea |
2579 | of how the \fIevent.h\fR header can be found. |
2978 | of how the \fIevent.h\fR header can be found, the default is \f(CW"event.h"\fR. |
2580 | .IP "\s-1EV_PROTOTYPES\s0" 4 |
2979 | .IP "\s-1EV_PROTOTYPES\s0" 4 |
2581 | .IX Item "EV_PROTOTYPES" |
2980 | .IX Item "EV_PROTOTYPES" |
2582 | If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function |
2981 | If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function |
2583 | prototypes, but still define all the structs and other symbols. This is |
2982 | prototypes, but still define all the structs and other symbols. This is |
2584 | occasionally useful if you want to provide your own wrapper functions |
2983 | occasionally useful if you want to provide your own wrapper functions |
… | |
… | |
2628 | defined to be \f(CW0\fR, then they are not. |
3027 | defined to be \f(CW0\fR, then they are not. |
2629 | .IP "\s-1EV_FORK_ENABLE\s0" 4 |
3028 | .IP "\s-1EV_FORK_ENABLE\s0" 4 |
2630 | .IX Item "EV_FORK_ENABLE" |
3029 | .IX Item "EV_FORK_ENABLE" |
2631 | If undefined or defined to be \f(CW1\fR, then fork watchers are supported. If |
3030 | If undefined or defined to be \f(CW1\fR, then fork watchers are supported. If |
2632 | defined to be \f(CW0\fR, then they are not. |
3031 | defined to be \f(CW0\fR, then they are not. |
|
|
3032 | .IP "\s-1EV_ASYNC_ENABLE\s0" 4 |
|
|
3033 | .IX Item "EV_ASYNC_ENABLE" |
|
|
3034 | If undefined or defined to be \f(CW1\fR, then async watchers are supported. If |
|
|
3035 | defined to be \f(CW0\fR, then they are not. |
2633 | .IP "\s-1EV_MINIMAL\s0" 4 |
3036 | .IP "\s-1EV_MINIMAL\s0" 4 |
2634 | .IX Item "EV_MINIMAL" |
3037 | .IX Item "EV_MINIMAL" |
2635 | If you need to shave off some kilobytes of code at the expense of some |
3038 | If you need to shave off some kilobytes of code at the expense of some |
2636 | speed, define this symbol to \f(CW1\fR. Currently only used for gcc to override |
3039 | speed, define this symbol to \f(CW1\fR. Currently only used for gcc to override |
2637 | some inlining decisions, saves roughly 30% codesize of amd64. |
3040 | some inlining decisions, saves roughly 30% codesize of amd64. |
… | |
… | |
2641 | pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more |
3044 | pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more |
2642 | than enough. If you need to manage thousands of children you might want to |
3045 | than enough. If you need to manage thousands of children you might want to |
2643 | increase this value (\fImust\fR be a power of two). |
3046 | increase this value (\fImust\fR be a power of two). |
2644 | .IP "\s-1EV_INOTIFY_HASHSIZE\s0" 4 |
3047 | .IP "\s-1EV_INOTIFY_HASHSIZE\s0" 4 |
2645 | .IX Item "EV_INOTIFY_HASHSIZE" |
3048 | .IX Item "EV_INOTIFY_HASHSIZE" |
2646 | \&\f(CW\*(C`ev_staz\*(C'\fR watchers use a small hash table to distribute workload by |
3049 | \&\f(CW\*(C`ev_stat\*(C'\fR watchers use a small hash table to distribute workload by |
2647 | inotify watch id. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), |
3050 | inotify watch id. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), |
2648 | usually more than enough. If you need to manage thousands of \f(CW\*(C`ev_stat\*(C'\fR |
3051 | usually more than enough. If you need to manage thousands of \f(CW\*(C`ev_stat\*(C'\fR |
2649 | watchers you might want to increase this value (\fImust\fR be a power of |
3052 | watchers you might want to increase this value (\fImust\fR be a power of |
2650 | two). |
3053 | two). |
2651 | .IP "\s-1EV_COMMON\s0" 4 |
3054 | .IP "\s-1EV_COMMON\s0" 4 |
… | |
… | |
2679 | .Sh "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0" |
3082 | .Sh "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0" |
2680 | .IX Subsection "EXPORTED API SYMBOLS" |
3083 | .IX Subsection "EXPORTED API SYMBOLS" |
2681 | If you need to re-export the \s-1API\s0 (e.g. via a dll) and you need a list of |
3084 | If you need to re-export the \s-1API\s0 (e.g. via a dll) and you need a list of |
2682 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
3085 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
2683 | all public symbols, one per line: |
3086 | all public symbols, one per line: |
2684 | .Sp |
3087 | .PP |
2685 | .Vb 2 |
3088 | .Vb 2 |
2686 | \& Symbols.ev for libev proper |
3089 | \& Symbols.ev for libev proper |
2687 | \& Symbols.event for the libevent emulation |
3090 | \& Symbols.event for the libevent emulation |
2688 | .Ve |
3091 | .Ve |
2689 | .Sp |
3092 | .PP |
2690 | This can also be used to rename all public symbols to avoid clashes with |
3093 | This can also be used to rename all public symbols to avoid clashes with |
2691 | multiple versions of libev linked together (which is obviously bad in |
3094 | multiple versions of libev linked together (which is obviously bad in |
2692 | itself, but sometimes it is inconvinient to avoid this). |
3095 | itself, but sometimes it is inconvinient to avoid this). |
2693 | .Sp |
3096 | .PP |
2694 | A sed command like this will create wrapper \f(CW\*(C`#define\*(C'\fR's that you need to |
3097 | A sed command like this will create wrapper \f(CW\*(C`#define\*(C'\fR's that you need to |
2695 | include before including \fIev.h\fR: |
3098 | include before including \fIev.h\fR: |
2696 | .Sp |
3099 | .PP |
2697 | .Vb 1 |
3100 | .Vb 1 |
2698 | \& <Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h |
3101 | \& <Symbols.ev sed \-e "s/.*/#define & myprefix_&/" >wrap.h |
2699 | .Ve |
3102 | .Ve |
2700 | .Sp |
3103 | .PP |
2701 | This would create a file \fIwrap.h\fR which essentially looks like this: |
3104 | This would create a file \fIwrap.h\fR which essentially looks like this: |
2702 | .Sp |
3105 | .PP |
2703 | .Vb 4 |
3106 | .Vb 4 |
2704 | \& #define ev_backend myprefix_ev_backend |
3107 | \& #define ev_backend myprefix_ev_backend |
2705 | \& #define ev_check_start myprefix_ev_check_start |
3108 | \& #define ev_check_start myprefix_ev_check_start |
2706 | \& #define ev_check_stop myprefix_ev_check_stop |
3109 | \& #define ev_check_stop myprefix_ev_check_stop |
2707 | \& ... |
3110 | \& ... |
… | |
… | |
2713 | (<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
3116 | (<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
2714 | the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public |
3117 | the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public |
2715 | interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file |
3118 | interface) and \fI\s-1EV\s0.xs\fR (implementation) files. Only the \fI\s-1EV\s0.xs\fR file |
2716 | will be compiled. It is pretty complex because it provides its own header |
3119 | will be compiled. It is pretty complex because it provides its own header |
2717 | file. |
3120 | file. |
2718 | .Sp |
3121 | .PP |
2719 | The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file |
3122 | The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file |
2720 | that everybody includes and which overrides some configure choices: |
3123 | that everybody includes and which overrides some configure choices: |
2721 | .Sp |
3124 | .PP |
2722 | .Vb 9 |
3125 | .Vb 9 |
2723 | \& #define EV_MINIMAL 1 |
3126 | \& #define EV_MINIMAL 1 |
2724 | \& #define EV_USE_POLL 0 |
3127 | \& #define EV_USE_POLL 0 |
2725 | \& #define EV_MULTIPLICITY 0 |
3128 | \& #define EV_MULTIPLICITY 0 |
2726 | \& #define EV_PERIODIC_ENABLE 0 |
3129 | \& #define EV_PERIODIC_ENABLE 0 |
2727 | \& #define EV_STAT_ENABLE 0 |
3130 | \& #define EV_STAT_ENABLE 0 |
2728 | \& #define EV_FORK_ENABLE 0 |
3131 | \& #define EV_FORK_ENABLE 0 |
2729 | \& #define EV_CONFIG_H <config.h> |
3132 | \& #define EV_CONFIG_H <config.h> |
2730 | \& #define EV_MINPRI 0 |
3133 | \& #define EV_MINPRI 0 |
2731 | \& #define EV_MAXPRI 0 |
3134 | \& #define EV_MAXPRI 0 |
2732 | .Ve |
3135 | \& |
2733 | .Sp |
|
|
2734 | .Vb 1 |
|
|
2735 | \& #include "ev++.h" |
3136 | \& #include "ev++.h" |
2736 | .Ve |
3137 | .Ve |
2737 | .Sp |
3138 | .PP |
2738 | And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled: |
3139 | And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled: |
2739 | .Sp |
3140 | .PP |
2740 | .Vb 2 |
3141 | .Vb 2 |
2741 | \& #include "ev_cpp.h" |
3142 | \& #include "ev_cpp.h" |
2742 | \& #include "ev.c" |
3143 | \& #include "ev.c" |
2743 | .Ve |
3144 | .Ve |
2744 | .SH "COMPLEXITIES" |
3145 | .SH "COMPLEXITIES" |
2745 | .IX Header "COMPLEXITIES" |
3146 | .IX Header "COMPLEXITIES" |
2746 | In this section the complexities of (many of) the algorithms used inside |
3147 | In this section the complexities of (many of) the algorithms used inside |
2747 | libev will be explained. For complexity discussions about backends see the |
3148 | libev will be explained. For complexity discussions about backends see the |
2748 | documentation for \f(CW\*(C`ev_default_init\*(C'\fR. |
3149 | documentation for \f(CW\*(C`ev_default_init\*(C'\fR. |
2749 | .Sp |
3150 | .PP |
2750 | All of the following are about amortised time: If an array needs to be |
3151 | All of the following are about amortised time: If an array needs to be |
2751 | extended, libev needs to realloc and move the whole array, but this |
3152 | extended, libev needs to realloc and move the whole array, but this |
2752 | happens asymptotically never with higher number of elements, so O(1) might |
3153 | happens asymptotically never with higher number of elements, so O(1) might |
2753 | mean it might do a lengthy realloc operation in rare cases, but on average |
3154 | mean it might do a lengthy realloc operation in rare cases, but on average |
2754 | it is much faster and asymptotically approaches constant time. |
3155 | it is much faster and asymptotically approaches constant time. |
2755 | .RS 4 |
|
|
2756 | .IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4 |
3156 | .IP "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" 4 |
2757 | .IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" |
3157 | .IX Item "Starting and stopping timer/periodic watchers: O(log skipped_other_timers)" |
2758 | This means that, when you have a watcher that triggers in one hour and |
3158 | This means that, when you have a watcher that triggers in one hour and |
2759 | there are 100 watchers that would trigger before that then inserting will |
3159 | there are 100 watchers that would trigger before that then inserting will |
2760 | have to skip those 100 watchers. |
3160 | have to skip roughly seven (\f(CW\*(C`ld 100\*(C'\fR) of these watchers. |
2761 | .IP "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 4 |
3161 | .IP "Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers)" 4 |
2762 | .IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" |
3162 | .IX Item "Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers)" |
2763 | That means that for changing a timer costs less than removing/adding them |
3163 | That means that changing a timer costs less than removing/adding them |
2764 | as only the relative motion in the event queue has to be paid for. |
3164 | as only the relative motion in the event queue has to be paid for. |
2765 | .IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4 |
3165 | .IP "Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1)" 4 |
2766 | .IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)" |
3166 | .IX Item "Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1)" |
2767 | These just add the watcher into an array or at the head of a list. |
3167 | These just add the watcher into an array or at the head of a list. |
|
|
3168 | .IP "Stopping check/prepare/idle/fork/async watchers: O(1)" 4 |
2768 | =item Stopping check/prepare/idle watchers: O(1) |
3169 | .IX Item "Stopping check/prepare/idle/fork/async watchers: O(1)" |
|
|
3170 | .PD 0 |
2769 | .IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4 |
3171 | .IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4 |
2770 | .IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))" |
3172 | .IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))" |
|
|
3173 | .PD |
2771 | These watchers are stored in lists then need to be walked to find the |
3174 | These watchers are stored in lists then need to be walked to find the |
2772 | correct watcher to remove. The lists are usually short (you don't usually |
3175 | correct watcher to remove. The lists are usually short (you don't usually |
2773 | have many watchers waiting for the same fd or signal). |
3176 | have many watchers waiting for the same fd or signal). |
2774 | .IP "Finding the next timer per loop iteration: O(1)" 4 |
3177 | .IP "Finding the next timer in each loop iteration: O(1)" 4 |
2775 | .IX Item "Finding the next timer per loop iteration: O(1)" |
3178 | .IX Item "Finding the next timer in each loop iteration: O(1)" |
2776 | .PD 0 |
3179 | By virtue of using a binary heap, the next timer is always found at the |
|
|
3180 | beginning of the storage array. |
2777 | .IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4 |
3181 | .IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4 |
2778 | .IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" |
3182 | .IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" |
2779 | .PD |
|
|
2780 | A change means an I/O watcher gets started or stopped, which requires |
3183 | A change means an I/O watcher gets started or stopped, which requires |
2781 | libev to recalculate its status (and possibly tell the kernel). |
3184 | libev to recalculate its status (and possibly tell the kernel, depending |
2782 | .IP "Activating one watcher: O(1)" 4 |
3185 | on backend and wether \f(CW\*(C`ev_io_set\*(C'\fR was used). |
2783 | .IX Item "Activating one watcher: O(1)" |
3186 | .IP "Activating one watcher (putting it into the pending state): O(1)" 4 |
|
|
3187 | .IX Item "Activating one watcher (putting it into the pending state): O(1)" |
2784 | .PD 0 |
3188 | .PD 0 |
2785 | .IP "Priority handling: O(number_of_priorities)" 4 |
3189 | .IP "Priority handling: O(number_of_priorities)" 4 |
2786 | .IX Item "Priority handling: O(number_of_priorities)" |
3190 | .IX Item "Priority handling: O(number_of_priorities)" |
2787 | .PD |
3191 | .PD |
2788 | Priorities are implemented by allocating some space for each |
3192 | Priorities are implemented by allocating some space for each |
2789 | priority. When doing priority-based operations, libev usually has to |
3193 | priority. When doing priority-based operations, libev usually has to |
2790 | linearly search all the priorities. |
3194 | linearly search all the priorities, but starting/stopping and activating |
2791 | .RE |
3195 | watchers becomes O(1) w.r.t. priority handling. |
2792 | .RS 4 |
3196 | .IP "Sending an ev_async: O(1)" 4 |
|
|
3197 | .IX Item "Sending an ev_async: O(1)" |
|
|
3198 | .PD 0 |
|
|
3199 | .IP "Processing ev_async_send: O(number_of_async_watchers)" 4 |
|
|
3200 | .IX Item "Processing ev_async_send: O(number_of_async_watchers)" |
|
|
3201 | .IP "Processing signals: O(max_signal_number)" 4 |
|
|
3202 | .IX Item "Processing signals: O(max_signal_number)" |
|
|
3203 | .PD |
|
|
3204 | Sending involves a syscall \fIiff\fR there were no other \f(CW\*(C`ev_async_send\*(C'\fR |
|
|
3205 | calls in the current loop iteration. Checking for async and signal events |
|
|
3206 | involves iterating over all running async watchers or all signal numbers. |
|
|
3207 | .SH "Win32 platform limitations and workarounds" |
|
|
3208 | .IX Header "Win32 platform limitations and workarounds" |
|
|
3209 | Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev |
|
|
3210 | requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 |
|
|
3211 | model. Libev still offers limited functionality on this platform in |
|
|
3212 | the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket |
|
|
3213 | descriptors. This only applies when using Win32 natively, not when using |
|
|
3214 | e.g. cygwin. |
|
|
3215 | .PP |
|
|
3216 | There is no supported compilation method available on windows except |
|
|
3217 | embedding it into other applications. |
|
|
3218 | .PP |
|
|
3219 | Due to the many, low, and arbitrary limits on the win32 platform and the |
|
|
3220 | abysmal performance of winsockets, using a large number of sockets is not |
|
|
3221 | recommended (and not reasonable). If your program needs to use more than |
|
|
3222 | a hundred or so sockets, then likely it needs to use a totally different |
|
|
3223 | implementation for windows, as libev offers the \s-1POSIX\s0 model, which cannot |
|
|
3224 | be implemented efficiently on windows (microsoft monopoly games). |
|
|
3225 | .IP "The winsocket select function" 4 |
|
|
3226 | .IX Item "The winsocket select function" |
|
|
3227 | The winsocket \f(CW\*(C`select\*(C'\fR function doesn't follow \s-1POSIX\s0 in that it requires |
|
|
3228 | socket \fIhandles\fR and not socket \fIfile descriptors\fR. This makes select |
|
|
3229 | very inefficient, and also requires a mapping from file descriptors |
|
|
3230 | to socket handles. See the discussion of the \f(CW\*(C`EV_SELECT_USE_FD_SET\*(C'\fR, |
|
|
3231 | \&\f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR and \f(CW\*(C`EV_FD_TO_WIN32_HANDLE\*(C'\fR preprocessor |
|
|
3232 | symbols for more info. |
|
|
3233 | .Sp |
|
|
3234 | The configuration for a \*(L"naked\*(R" win32 using the microsoft runtime |
|
|
3235 | libraries and raw winsocket select is: |
|
|
3236 | .Sp |
|
|
3237 | .Vb 2 |
|
|
3238 | \& #define EV_USE_SELECT 1 |
|
|
3239 | \& #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
|
|
3240 | .Ve |
|
|
3241 | .Sp |
|
|
3242 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
|
|
3243 | complexity in the O(nA\*^X) range when using win32. |
|
|
3244 | .IP "Limited number of file descriptors" 4 |
|
|
3245 | .IX Item "Limited number of file descriptors" |
|
|
3246 | Windows has numerous arbitrary (and low) limits on things. Early versions |
|
|
3247 | of winsocket's select only supported waiting for a max. of \f(CW64\fR handles |
|
|
3248 | (probably owning to the fact that all windows kernels can only wait for |
|
|
3249 | \&\f(CW64\fR things at the same time internally; microsoft recommends spawning a |
|
|
3250 | chain of threads and wait for 63 handles and the previous thread in each). |
|
|
3251 | .Sp |
|
|
3252 | Newer versions support more handles, but you need to define \f(CW\*(C`FD_SETSIZE\*(C'\fR |
|
|
3253 | to some high number (e.g. \f(CW2048\fR) before compiling the winsocket select |
|
|
3254 | call (which might be in libev or elsewhere, for example, perl does its own |
|
|
3255 | select emulation on windows). |
|
|
3256 | .Sp |
|
|
3257 | Another limit is the number of file descriptors in the microsoft runtime |
|
|
3258 | libraries, which by default is \f(CW64\fR (there must be a hidden \fI64\fR fetish |
|
|
3259 | or something like this inside microsoft). You can increase this by calling |
|
|
3260 | \&\f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR (another |
|
|
3261 | arbitrary limit), but is broken in many versions of the microsoft runtime |
|
|
3262 | libraries. |
|
|
3263 | .Sp |
|
|
3264 | This might get you to about \f(CW512\fR or \f(CW2048\fR sockets (depending on |
|
|
3265 | windows version and/or the phase of the moon). To get more, you need to |
|
|
3266 | wrap all I/O functions and provide your own fd management, but the cost of |
|
|
3267 | calling select (O(nA\*^X)) will likely make this unworkable. |
2793 | .SH "AUTHOR" |
3268 | .SH "AUTHOR" |
2794 | .IX Header "AUTHOR" |
3269 | .IX Header "AUTHOR" |
2795 | Marc Lehmann <libev@schmorp.de>. |
3270 | Marc Lehmann <libev@schmorp.de>. |
|
|
3271 | .SH "POD ERRORS" |
|
|
3272 | .IX Header "POD ERRORS" |
|
|
3273 | Hey! \fBThe above document had some coding errors, which are explained below:\fR |
|
|
3274 | .IP "Around line 2996:" 4 |
|
|
3275 | .IX Item "Around line 2996:" |
|
|
3276 | You forgot a '=back' before '=head2' |