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124 | .\" ======================================================================== |
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134 | .\" |
126 | .IX Title "LIBEV 3" |
135 | .IX Title "LIBEV 3" |
127 | .TH LIBEV 3 "2011-01-11" "libev-4.03" "libev - high performance full featured event loop" |
136 | .TH LIBEV 3 "2019-06-25" "libev-4.25" "libev - high performance full featured event loop" |
128 | .\" For nroff, turn off justification. Always turn off hyphenation; it makes |
137 | .\" For nroff, turn off justification. Always turn off hyphenation; it makes |
129 | .\" way too many mistakes in technical documents. |
138 | .\" way too many mistakes in technical documents. |
130 | .if n .ad l |
139 | .if n .ad l |
131 | .nh |
140 | .nh |
132 | .SH "NAME" |
141 | .SH "NAME" |
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134 | .SH "SYNOPSIS" |
143 | .SH "SYNOPSIS" |
135 | .IX Header "SYNOPSIS" |
144 | .IX Header "SYNOPSIS" |
136 | .Vb 1 |
145 | .Vb 1 |
137 | \& #include <ev.h> |
146 | \& #include <ev.h> |
138 | .Ve |
147 | .Ve |
139 | .SS "\s-1EXAMPLE\s0 \s-1PROGRAM\s0" |
148 | .SS "\s-1EXAMPLE PROGRAM\s0" |
140 | .IX Subsection "EXAMPLE PROGRAM" |
149 | .IX Subsection "EXAMPLE PROGRAM" |
141 | .Vb 2 |
150 | .Vb 2 |
142 | \& // a single header file is required |
151 | \& // a single header file is required |
143 | \& #include <ev.h> |
152 | \& #include <ev.h> |
144 | \& |
153 | \& |
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189 | \& ev_timer_start (loop, &timeout_watcher); |
198 | \& ev_timer_start (loop, &timeout_watcher); |
190 | \& |
199 | \& |
191 | \& // now wait for events to arrive |
200 | \& // now wait for events to arrive |
192 | \& ev_run (loop, 0); |
201 | \& ev_run (loop, 0); |
193 | \& |
202 | \& |
194 | \& // unloop was called, so exit |
203 | \& // break was called, so exit |
195 | \& return 0; |
204 | \& return 0; |
196 | \& } |
205 | \& } |
197 | .Ve |
206 | .Ve |
198 | .SH "ABOUT THIS DOCUMENT" |
207 | .SH "ABOUT THIS DOCUMENT" |
199 | .IX Header "ABOUT THIS DOCUMENT" |
208 | .IX Header "ABOUT THIS DOCUMENT" |
… | |
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212 | throughout this document. |
221 | throughout this document. |
213 | .SH "WHAT TO READ WHEN IN A HURRY" |
222 | .SH "WHAT TO READ WHEN IN A HURRY" |
214 | .IX Header "WHAT TO READ WHEN IN A HURRY" |
223 | .IX Header "WHAT TO READ WHEN IN A HURRY" |
215 | This manual tries to be very detailed, but unfortunately, this also makes |
224 | This manual tries to be very detailed, but unfortunately, this also makes |
216 | it very long. If you just want to know the basics of libev, I suggest |
225 | it very long. If you just want to know the basics of libev, I suggest |
217 | reading \*(L"\s-1ANATOMY\s0 \s-1OF\s0 A \s-1WATCHER\s0\*(R", then the \*(L"\s-1EXAMPLE\s0 \s-1PROGRAM\s0\*(R" above and |
226 | reading \*(L"\s-1ANATOMY OF A WATCHER\*(R"\s0, then the \*(L"\s-1EXAMPLE PROGRAM\*(R"\s0 above and |
218 | look up the missing functions in \*(L"\s-1GLOBAL\s0 \s-1FUNCTIONS\s0\*(R" and the \f(CW\*(C`ev_io\*(C'\fR and |
227 | look up the missing functions in \*(L"\s-1GLOBAL FUNCTIONS\*(R"\s0 and the \f(CW\*(C`ev_io\*(C'\fR and |
219 | \&\f(CW\*(C`ev_timer\*(C'\fR sections in \*(L"\s-1WATCHER\s0 \s-1TYPES\s0\*(R". |
228 | \&\f(CW\*(C`ev_timer\*(C'\fR sections in \*(L"\s-1WATCHER TYPES\*(R"\s0. |
220 | .SH "ABOUT LIBEV" |
229 | .SH "ABOUT LIBEV" |
221 | .IX Header "ABOUT LIBEV" |
230 | .IX Header "ABOUT LIBEV" |
222 | Libev is an event loop: you register interest in certain events (such as a |
231 | Libev is an event loop: you register interest in certain events (such as a |
223 | file descriptor being readable or a timeout occurring), and it will manage |
232 | file descriptor being readable or a timeout occurring), and it will manage |
224 | these event sources and provide your program with events. |
233 | these event sources and provide your program with events. |
… | |
… | |
231 | watchers\fR, which are relatively small C structures you initialise with the |
240 | watchers\fR, which are relatively small C structures you initialise with the |
232 | details of the event, and then hand it over to libev by \fIstarting\fR the |
241 | details of the event, and then hand it over to libev by \fIstarting\fR the |
233 | watcher. |
242 | watcher. |
234 | .SS "\s-1FEATURES\s0" |
243 | .SS "\s-1FEATURES\s0" |
235 | .IX Subsection "FEATURES" |
244 | .IX Subsection "FEATURES" |
236 | Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the Linux-specific \f(CW\*(C`epoll\*(C'\fR, the |
245 | Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the Linux-specific aio and \f(CW\*(C`epoll\*(C'\fR |
237 | BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port mechanisms |
246 | interfaces, the BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port |
238 | for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR interface |
247 | mechanisms for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR |
239 | (for \f(CW\*(C`ev_stat\*(C'\fR), Linux eventfd/signalfd (for faster and cleaner |
248 | interface (for \f(CW\*(C`ev_stat\*(C'\fR), Linux eventfd/signalfd (for faster and cleaner |
240 | inter-thread wakeup (\f(CW\*(C`ev_async\*(C'\fR)/signal handling (\f(CW\*(C`ev_signal\*(C'\fR)) relative |
249 | inter-thread wakeup (\f(CW\*(C`ev_async\*(C'\fR)/signal handling (\f(CW\*(C`ev_signal\*(C'\fR)) relative |
241 | timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers with customised rescheduling |
250 | timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers with customised rescheduling |
242 | (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals (\f(CW\*(C`ev_signal\*(C'\fR), process status |
251 | (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals (\f(CW\*(C`ev_signal\*(C'\fR), process status |
243 | change events (\f(CW\*(C`ev_child\*(C'\fR), and event watchers dealing with the event |
252 | change events (\f(CW\*(C`ev_child\*(C'\fR), and event watchers dealing with the event |
244 | loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR, \f(CW\*(C`ev_embed\*(C'\fR, \f(CW\*(C`ev_prepare\*(C'\fR and |
253 | loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR, \f(CW\*(C`ev_embed\*(C'\fR, \f(CW\*(C`ev_prepare\*(C'\fR and |
245 | \&\f(CW\*(C`ev_check\*(C'\fR watchers) as well as file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even |
254 | \&\f(CW\*(C`ev_check\*(C'\fR watchers) as well as file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even |
246 | limited support for fork events (\f(CW\*(C`ev_fork\*(C'\fR). |
255 | limited support for fork events (\f(CW\*(C`ev_fork\*(C'\fR). |
247 | .PP |
256 | .PP |
248 | It also is quite fast (see this |
257 | It also is quite fast (see this |
249 | <benchmark> comparing it to libevent |
258 | benchmark <http://libev.schmorp.de/bench.html> comparing it to libevent |
250 | for example). |
259 | for example). |
251 | .SS "\s-1CONVENTIONS\s0" |
260 | .SS "\s-1CONVENTIONS\s0" |
252 | .IX Subsection "CONVENTIONS" |
261 | .IX Subsection "CONVENTIONS" |
253 | Libev is very configurable. In this manual the default (and most common) |
262 | Libev is very configurable. In this manual the default (and most common) |
254 | configuration will be described, which supports multiple event loops. For |
263 | configuration will be described, which supports multiple event loops. For |
255 | more info about various configuration options please have a look at |
264 | more info about various configuration options please have a look at |
256 | \&\fB\s-1EMBED\s0\fR section in this manual. If libev was configured without support |
265 | \&\fB\s-1EMBED\s0\fR section in this manual. If libev was configured without support |
257 | for multiple event loops, then all functions taking an initial argument of |
266 | for multiple event loops, then all functions taking an initial argument of |
258 | name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) will not have |
267 | name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) will not have |
259 | this argument. |
268 | this argument. |
260 | .SS "\s-1TIME\s0 \s-1REPRESENTATION\s0" |
269 | .SS "\s-1TIME REPRESENTATION\s0" |
261 | .IX Subsection "TIME REPRESENTATION" |
270 | .IX Subsection "TIME REPRESENTATION" |
262 | Libev represents time as a single floating point number, representing |
271 | Libev represents time as a single floating point number, representing |
263 | the (fractional) number of seconds since the (\s-1POSIX\s0) epoch (in practice |
272 | the (fractional) number of seconds since the (\s-1POSIX\s0) epoch (in practice |
264 | somewhere near the beginning of 1970, details are complicated, don't |
273 | somewhere near the beginning of 1970, details are complicated, don't |
265 | ask). This type is called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use |
274 | ask). This type is called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use |
… | |
… | |
282 | When libev detects a usage error such as a negative timer interval, then |
291 | When libev detects a usage error such as a negative timer interval, then |
283 | it will print a diagnostic message and abort (via the \f(CW\*(C`assert\*(C'\fR mechanism, |
292 | it will print a diagnostic message and abort (via the \f(CW\*(C`assert\*(C'\fR mechanism, |
284 | so \f(CW\*(C`NDEBUG\*(C'\fR will disable this checking): these are programming errors in |
293 | so \f(CW\*(C`NDEBUG\*(C'\fR will disable this checking): these are programming errors in |
285 | the libev caller and need to be fixed there. |
294 | the libev caller and need to be fixed there. |
286 | .PP |
295 | .PP |
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296 | Via the \f(CW\*(C`EV_FREQUENT\*(C'\fR macro you can compile in and/or enable extensive |
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297 | consistency checking code inside libev that can be used to check for |
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298 | internal inconsistencies, suually caused by application bugs. |
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299 | .PP |
287 | Libev also has a few internal error-checking \f(CW\*(C`assert\*(C'\fRions, and also has |
300 | Libev also has a few internal error-checking \f(CW\*(C`assert\*(C'\fRions. These do not |
288 | extensive consistency checking code. These do not trigger under normal |
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289 | circumstances, as they indicate either a bug in libev or worse. |
301 | trigger under normal circumstances, as they indicate either a bug in libev |
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302 | or worse. |
290 | .SH "GLOBAL FUNCTIONS" |
303 | .SH "GLOBAL FUNCTIONS" |
291 | .IX Header "GLOBAL FUNCTIONS" |
304 | .IX Header "GLOBAL FUNCTIONS" |
292 | These functions can be called anytime, even before initialising the |
305 | These functions can be called anytime, even before initialising the |
293 | library in any way. |
306 | library in any way. |
294 | .IP "ev_tstamp ev_time ()" 4 |
307 | .IP "ev_tstamp ev_time ()" 4 |
295 | .IX Item "ev_tstamp ev_time ()" |
308 | .IX Item "ev_tstamp ev_time ()" |
296 | Returns the current time as libev would use it. Please note that the |
309 | Returns the current time as libev would use it. Please note that the |
297 | \&\f(CW\*(C`ev_now\*(C'\fR function is usually faster and also often returns the timestamp |
310 | \&\f(CW\*(C`ev_now\*(C'\fR function is usually faster and also often returns the timestamp |
298 | you actually want to know. Also interesting is the combination of |
311 | you actually want to know. Also interesting is the combination of |
299 | \&\f(CW\*(C`ev_update_now\*(C'\fR and \f(CW\*(C`ev_now\*(C'\fR. |
312 | \&\f(CW\*(C`ev_now_update\*(C'\fR and \f(CW\*(C`ev_now\*(C'\fR. |
300 | .IP "ev_sleep (ev_tstamp interval)" 4 |
313 | .IP "ev_sleep (ev_tstamp interval)" 4 |
301 | .IX Item "ev_sleep (ev_tstamp interval)" |
314 | .IX Item "ev_sleep (ev_tstamp interval)" |
302 | Sleep for the given interval: The current thread will be blocked until |
315 | Sleep for the given interval: The current thread will be blocked |
303 | either it is interrupted or the given time interval has passed. Basically |
316 | until either it is interrupted or the given time interval has |
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317 | passed (approximately \- it might return a bit earlier even if not |
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318 | interrupted). Returns immediately if \f(CW\*(C`interval <= 0\*(C'\fR. |
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319 | .Sp |
304 | this is a sub-second-resolution \f(CW\*(C`sleep ()\*(C'\fR. |
320 | Basically this is a sub-second-resolution \f(CW\*(C`sleep ()\*(C'\fR. |
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321 | .Sp |
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322 | The range of the \f(CW\*(C`interval\*(C'\fR is limited \- libev only guarantees to work |
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323 | with sleep times of up to one day (\f(CW\*(C`interval <= 86400\*(C'\fR). |
305 | .IP "int ev_version_major ()" 4 |
324 | .IP "int ev_version_major ()" 4 |
306 | .IX Item "int ev_version_major ()" |
325 | .IX Item "int ev_version_major ()" |
307 | .PD 0 |
326 | .PD 0 |
308 | .IP "int ev_version_minor ()" 4 |
327 | .IP "int ev_version_minor ()" 4 |
309 | .IX Item "int ev_version_minor ()" |
328 | .IX Item "int ev_version_minor ()" |
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361 | current system. To find which embeddable backends might be supported on |
380 | current system. To find which embeddable backends might be supported on |
362 | the current system, you would need to look at \f(CW\*(C`ev_embeddable_backends () |
381 | the current system, you would need to look at \f(CW\*(C`ev_embeddable_backends () |
363 | & ev_supported_backends ()\*(C'\fR, likewise for recommended ones. |
382 | & ev_supported_backends ()\*(C'\fR, likewise for recommended ones. |
364 | .Sp |
383 | .Sp |
365 | See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
384 | See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
366 | .IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4 |
385 | .IP "ev_set_allocator (void *(*cb)(void *ptr, long size) throw ())" 4 |
367 | .IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))" |
386 | .IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size) throw ())" |
368 | Sets the allocation function to use (the prototype is similar \- the |
387 | Sets the allocation function to use (the prototype is similar \- the |
369 | semantics are identical to the \f(CW\*(C`realloc\*(C'\fR C89/SuS/POSIX function). It is |
388 | semantics are identical to the \f(CW\*(C`realloc\*(C'\fR C89/SuS/POSIX function). It is |
370 | used to allocate and free memory (no surprises here). If it returns zero |
389 | used to allocate and free memory (no surprises here). If it returns zero |
371 | when memory needs to be allocated (\f(CW\*(C`size != 0\*(C'\fR), the library might abort |
390 | when memory needs to be allocated (\f(CW\*(C`size != 0\*(C'\fR), the library might abort |
372 | or take some potentially destructive action. |
391 | or take some potentially destructive action. |
… | |
… | |
377 | .Sp |
396 | .Sp |
378 | You could override this function in high-availability programs to, say, |
397 | You could override this function in high-availability programs to, say, |
379 | free some memory if it cannot allocate memory, to use a special allocator, |
398 | free some memory if it cannot allocate memory, to use a special allocator, |
380 | or even to sleep a while and retry until some memory is available. |
399 | or even to sleep a while and retry until some memory is available. |
381 | .Sp |
400 | .Sp |
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401 | Example: The following is the \f(CW\*(C`realloc\*(C'\fR function that libev itself uses |
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402 | which should work with \f(CW\*(C`realloc\*(C'\fR and \f(CW\*(C`free\*(C'\fR functions of all kinds and |
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403 | is probably a good basis for your own implementation. |
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404 | .Sp |
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405 | .Vb 5 |
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406 | \& static void * |
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407 | \& ev_realloc_emul (void *ptr, long size) EV_NOEXCEPT |
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408 | \& { |
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409 | \& if (size) |
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410 | \& return realloc (ptr, size); |
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411 | \& |
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412 | \& free (ptr); |
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413 | \& return 0; |
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414 | \& } |
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415 | .Ve |
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416 | .Sp |
382 | Example: Replace the libev allocator with one that waits a bit and then |
417 | Example: Replace the libev allocator with one that waits a bit and then |
383 | retries (example requires a standards-compliant \f(CW\*(C`realloc\*(C'\fR). |
418 | retries. |
384 | .Sp |
419 | .Sp |
385 | .Vb 6 |
420 | .Vb 8 |
386 | \& static void * |
421 | \& static void * |
387 | \& persistent_realloc (void *ptr, size_t size) |
422 | \& persistent_realloc (void *ptr, size_t size) |
388 | \& { |
423 | \& { |
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424 | \& if (!size) |
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425 | \& { |
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426 | \& free (ptr); |
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427 | \& return 0; |
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428 | \& } |
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429 | \& |
389 | \& for (;;) |
430 | \& for (;;) |
390 | \& { |
431 | \& { |
391 | \& void *newptr = realloc (ptr, size); |
432 | \& void *newptr = realloc (ptr, size); |
392 | \& |
433 | \& |
393 | \& if (newptr) |
434 | \& if (newptr) |
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398 | \& } |
439 | \& } |
399 | \& |
440 | \& |
400 | \& ... |
441 | \& ... |
401 | \& ev_set_allocator (persistent_realloc); |
442 | \& ev_set_allocator (persistent_realloc); |
402 | .Ve |
443 | .Ve |
403 | .IP "ev_set_syserr_cb (void (*cb)(const char *msg))" 4 |
444 | .IP "ev_set_syserr_cb (void (*cb)(const char *msg) throw ())" 4 |
404 | .IX Item "ev_set_syserr_cb (void (*cb)(const char *msg))" |
445 | .IX Item "ev_set_syserr_cb (void (*cb)(const char *msg) throw ())" |
405 | Set the callback function to call on a retryable system call error (such |
446 | Set the callback function to call on a retryable system call error (such |
406 | as failed select, poll, epoll_wait). The message is a printable string |
447 | as failed select, poll, epoll_wait). The message is a printable string |
407 | indicating the system call or subsystem causing the problem. If this |
448 | indicating the system call or subsystem causing the problem. If this |
408 | callback is set, then libev will expect it to remedy the situation, no |
449 | callback is set, then libev will expect it to remedy the situation, no |
409 | matter what, when it returns. That is, libev will generally retry the |
450 | matter what, when it returns. That is, libev will generally retry the |
… | |
… | |
508 | .IX Item "EVFLAG_NOENV" |
549 | .IX Item "EVFLAG_NOENV" |
509 | If this flag bit is or'ed into the flag value (or the program runs setuid |
550 | If this flag bit is or'ed into the flag value (or the program runs setuid |
510 | or setgid) then libev will \fInot\fR look at the environment variable |
551 | or setgid) then libev will \fInot\fR look at the environment variable |
511 | \&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will |
552 | \&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will |
512 | override the flags completely if it is found in the environment. This is |
553 | override the flags completely if it is found in the environment. This is |
513 | useful to try out specific backends to test their performance, or to work |
554 | useful to try out specific backends to test their performance, to work |
514 | around bugs. |
555 | around bugs, or to make libev threadsafe (accessing environment variables |
|
|
556 | cannot be done in a threadsafe way, but usually it works if no other |
|
|
557 | thread modifies them). |
515 | .ie n .IP """EVFLAG_FORKCHECK""" 4 |
558 | .ie n .IP """EVFLAG_FORKCHECK""" 4 |
516 | .el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4 |
559 | .el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4 |
517 | .IX Item "EVFLAG_FORKCHECK" |
560 | .IX Item "EVFLAG_FORKCHECK" |
518 | Instead of calling \f(CW\*(C`ev_loop_fork\*(C'\fR manually after a fork, you can also |
561 | Instead of calling \f(CW\*(C`ev_loop_fork\*(C'\fR manually after a fork, you can also |
519 | make libev check for a fork in each iteration by enabling this flag. |
562 | make libev check for a fork in each iteration by enabling this flag. |
520 | .Sp |
563 | .Sp |
521 | This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop, |
564 | This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop, |
522 | and thus this might slow down your event loop if you do a lot of loop |
565 | and thus this might slow down your event loop if you do a lot of loop |
523 | iterations and little real work, but is usually not noticeable (on my |
566 | iterations and little real work, but is usually not noticeable (on my |
524 | GNU/Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence |
567 | GNU/Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn |
525 | without a system call and thus \fIvery\fR fast, but my GNU/Linux system also has |
568 | sequence without a system call and thus \fIvery\fR fast, but my GNU/Linux |
526 | \&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster). |
569 | system also has \f(CW\*(C`pthread_atfork\*(C'\fR which is even faster). (Update: glibc |
|
|
570 | versions 2.25 apparently removed the \f(CW\*(C`getpid\*(C'\fR optimisation again). |
527 | .Sp |
571 | .Sp |
528 | The big advantage of this flag is that you can forget about fork (and |
572 | The big advantage of this flag is that you can forget about fork (and |
529 | forget about forgetting to tell libev about forking) when you use this |
573 | forget about forgetting to tell libev about forking, although you still |
530 | flag. |
574 | have to ignore \f(CW\*(C`SIGPIPE\*(C'\fR) when you use this flag. |
531 | .Sp |
575 | .Sp |
532 | This flag setting cannot be overridden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR |
576 | This flag setting cannot be overridden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR |
533 | environment variable. |
577 | environment variable. |
534 | .ie n .IP """EVFLAG_NOINOTIFY""" 4 |
578 | .ie n .IP """EVFLAG_NOINOTIFY""" 4 |
535 | .el .IP "\f(CWEVFLAG_NOINOTIFY\fR" 4 |
579 | .el .IP "\f(CWEVFLAG_NOINOTIFY\fR" 4 |
… | |
… | |
553 | example) that can't properly initialise their signal masks. |
597 | example) that can't properly initialise their signal masks. |
554 | .ie n .IP """EVFLAG_NOSIGMASK""" 4 |
598 | .ie n .IP """EVFLAG_NOSIGMASK""" 4 |
555 | .el .IP "\f(CWEVFLAG_NOSIGMASK\fR" 4 |
599 | .el .IP "\f(CWEVFLAG_NOSIGMASK\fR" 4 |
556 | .IX Item "EVFLAG_NOSIGMASK" |
600 | .IX Item "EVFLAG_NOSIGMASK" |
557 | When this flag is specified, then libev will avoid to modify the signal |
601 | When this flag is specified, then libev will avoid to modify the signal |
558 | mask. Specifically, this means you ahve to make sure signals are unblocked |
602 | mask. Specifically, this means you have to make sure signals are unblocked |
559 | when you want to receive them. |
603 | when you want to receive them. |
560 | .Sp |
604 | .Sp |
561 | This behaviour is useful when you want to do your own signal handling, or |
605 | This behaviour is useful when you want to do your own signal handling, or |
562 | want to handle signals only in specific threads and want to avoid libev |
606 | want to handle signals only in specific threads and want to avoid libev |
563 | unblocking the signals. |
607 | unblocking the signals. |
564 | .Sp |
608 | .Sp |
|
|
609 | It's also required by \s-1POSIX\s0 in a threaded program, as libev calls |
|
|
610 | \&\f(CW\*(C`sigprocmask\*(C'\fR, whose behaviour is officially unspecified. |
|
|
611 | .Sp |
565 | This flag's behaviour will become the default in future versions of libev. |
612 | This flag's behaviour will become the default in future versions of libev. |
566 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
613 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
567 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
614 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
568 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
615 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
569 | This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
616 | This is your standard \fBselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
570 | libev tries to roll its own fd_set with no limits on the number of fds, |
617 | libev tries to roll its own fd_set with no limits on the number of fds, |
571 | but if that fails, expect a fairly low limit on the number of fds when |
618 | but if that fails, expect a fairly low limit on the number of fds when |
572 | using this backend. It doesn't scale too well (O(highest_fd)), but its |
619 | using this backend. It doesn't scale too well (O(highest_fd)), but its |
573 | usually the fastest backend for a low number of (low-numbered :) fds. |
620 | usually the fastest backend for a low number of (low-numbered :) fds. |
574 | .Sp |
621 | .Sp |
… | |
… | |
582 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR to the \f(CW\*(C`readfds\*(C'\fR set and \f(CW\*(C`EV_WRITE\*(C'\fR to the |
629 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR to the \f(CW\*(C`readfds\*(C'\fR set and \f(CW\*(C`EV_WRITE\*(C'\fR to the |
583 | \&\f(CW\*(C`writefds\*(C'\fR set (and to work around Microsoft Windows bugs, also onto the |
630 | \&\f(CW\*(C`writefds\*(C'\fR set (and to work around Microsoft Windows bugs, also onto the |
584 | \&\f(CW\*(C`exceptfds\*(C'\fR set on that platform). |
631 | \&\f(CW\*(C`exceptfds\*(C'\fR set on that platform). |
585 | .ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4 |
632 | .ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4 |
586 | .el .IP "\f(CWEVBACKEND_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4 |
633 | .el .IP "\f(CWEVBACKEND_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4 |
587 | .IX Item "EVBACKEND_POLL (value 2, poll backend, available everywhere except on windows)" |
634 | .IX Item "EVBACKEND_POLL (value 2, poll backend, available everywhere except on windows)" |
588 | And this is your standard \fIpoll\fR\|(2) backend. It's more complicated |
635 | And this is your standard \fBpoll\fR\|(2) backend. It's more complicated |
589 | than select, but handles sparse fds better and has no artificial |
636 | than select, but handles sparse fds better and has no artificial |
590 | limit on the number of fds you can use (except it will slow down |
637 | limit on the number of fds you can use (except it will slow down |
591 | considerably with a lot of inactive fds). It scales similarly to select, |
638 | considerably with a lot of inactive fds). It scales similarly to select, |
592 | i.e. O(total_fds). See the entry for \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR, above, for |
639 | i.e. O(total_fds). See the entry for \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR, above, for |
593 | performance tips. |
640 | performance tips. |
594 | .Sp |
641 | .Sp |
595 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR to \f(CW\*(C`POLLIN | POLLERR | POLLHUP\*(C'\fR, and |
642 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR to \f(CW\*(C`POLLIN | POLLERR | POLLHUP\*(C'\fR, and |
596 | \&\f(CW\*(C`EV_WRITE\*(C'\fR to \f(CW\*(C`POLLOUT | POLLERR | POLLHUP\*(C'\fR. |
643 | \&\f(CW\*(C`EV_WRITE\*(C'\fR to \f(CW\*(C`POLLOUT | POLLERR | POLLHUP\*(C'\fR. |
597 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
644 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
598 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
645 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
599 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
646 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
600 | Use the linux-specific \fIepoll\fR\|(7) interface (for both pre\- and post\-2.6.9 |
647 | Use the Linux-specific \fBepoll\fR\|(7) interface (for both pre\- and post\-2.6.9 |
601 | kernels). |
648 | kernels). |
602 | .Sp |
649 | .Sp |
603 | For few fds, this backend is a bit little slower than poll and select, |
650 | For few fds, this backend is a bit little slower than poll and select, but |
604 | but it scales phenomenally better. While poll and select usually scale |
651 | it scales phenomenally better. While poll and select usually scale like |
605 | like O(total_fds) where n is the total number of fds (or the highest fd), |
652 | O(total_fds) where total_fds is the total number of fds (or the highest |
606 | epoll scales either O(1) or O(active_fds). |
653 | fd), epoll scales either O(1) or O(active_fds). |
607 | .Sp |
654 | .Sp |
608 | The epoll mechanism deserves honorable mention as the most misdesigned |
655 | The epoll mechanism deserves honorable mention as the most misdesigned |
609 | of the more advanced event mechanisms: mere annoyances include silently |
656 | of the more advanced event mechanisms: mere annoyances include silently |
610 | dropping file descriptors, requiring a system call per change per file |
657 | dropping file descriptors, requiring a system call per change per file |
611 | descriptor (and unnecessary guessing of parameters), problems with dup, |
658 | descriptor (and unnecessary guessing of parameters), problems with dup, |
… | |
… | |
614 | 0.1ms) and so on. The biggest issue is fork races, however \- if a program |
661 | 0.1ms) and so on. The biggest issue is fork races, however \- if a program |
615 | forks then \fIboth\fR parent and child process have to recreate the epoll |
662 | forks then \fIboth\fR parent and child process have to recreate the epoll |
616 | set, which can take considerable time (one syscall per file descriptor) |
663 | set, which can take considerable time (one syscall per file descriptor) |
617 | and is of course hard to detect. |
664 | and is of course hard to detect. |
618 | .Sp |
665 | .Sp |
619 | Epoll is also notoriously buggy \- embedding epoll fds \fIshould\fR work, but |
666 | Epoll is also notoriously buggy \- embedding epoll fds \fIshould\fR work, |
620 | of course \fIdoesn't\fR, and epoll just loves to report events for totally |
667 | but of course \fIdoesn't\fR, and epoll just loves to report events for |
621 | \&\fIdifferent\fR file descriptors (even already closed ones, so one cannot |
668 | totally \fIdifferent\fR file descriptors (even already closed ones, so |
622 | even remove them from the set) than registered in the set (especially |
669 | one cannot even remove them from the set) than registered in the set |
623 | on \s-1SMP\s0 systems). Libev tries to counter these spurious notifications by |
670 | (especially on \s-1SMP\s0 systems). Libev tries to counter these spurious |
624 | employing an additional generation counter and comparing that against the |
671 | notifications by employing an additional generation counter and comparing |
625 | events to filter out spurious ones, recreating the set when required. Last |
672 | that against the events to filter out spurious ones, recreating the set |
|
|
673 | when required. Epoll also erroneously rounds down timeouts, but gives you |
|
|
674 | no way to know when and by how much, so sometimes you have to busy-wait |
|
|
675 | because epoll returns immediately despite a nonzero timeout. And last |
626 | not least, it also refuses to work with some file descriptors which work |
676 | not least, it also refuses to work with some file descriptors which work |
627 | perfectly fine with \f(CW\*(C`select\*(C'\fR (files, many character devices...). |
677 | perfectly fine with \f(CW\*(C`select\*(C'\fR (files, many character devices...). |
628 | .Sp |
678 | .Sp |
629 | Epoll is truly the train wreck analog among event poll mechanisms, |
679 | Epoll is truly the train wreck among event poll mechanisms, a frankenpoll, |
630 | a frankenpoll, cobbled together in a hurry, no thought to design or |
680 | cobbled together in a hurry, no thought to design or interaction with |
631 | interaction with others. |
681 | others. Oh, the pain, will it ever stop... |
632 | .Sp |
682 | .Sp |
633 | While stopping, setting and starting an I/O watcher in the same iteration |
683 | While stopping, setting and starting an I/O watcher in the same iteration |
634 | will result in some caching, there is still a system call per such |
684 | will result in some caching, there is still a system call per such |
635 | incident (because the same \fIfile descriptor\fR could point to a different |
685 | incident (because the same \fIfile descriptor\fR could point to a different |
636 | \&\fIfile description\fR now), so its best to avoid that. Also, \f(CW\*(C`dup ()\*(C'\fR'ed |
686 | \&\fIfile description\fR now), so its best to avoid that. Also, \f(CW\*(C`dup ()\*(C'\fR'ed |
… | |
… | |
648 | All this means that, in practice, \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR can be as fast or |
698 | All this means that, in practice, \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR can be as fast or |
649 | faster than epoll for maybe up to a hundred file descriptors, depending on |
699 | faster than epoll for maybe up to a hundred file descriptors, depending on |
650 | the usage. So sad. |
700 | the usage. So sad. |
651 | .Sp |
701 | .Sp |
652 | While nominally embeddable in other event loops, this feature is broken in |
702 | While nominally embeddable in other event loops, this feature is broken in |
653 | all kernel versions tested so far. |
703 | a lot of kernel revisions, but probably(!) works in current versions. |
|
|
704 | .Sp |
|
|
705 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
|
|
706 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
|
|
707 | .ie n .IP """EVBACKEND_LINUXAIO"" (value 64, Linux)" 4 |
|
|
708 | .el .IP "\f(CWEVBACKEND_LINUXAIO\fR (value 64, Linux)" 4 |
|
|
709 | .IX Item "EVBACKEND_LINUXAIO (value 64, Linux)" |
|
|
710 | Use the Linux-specific Linux \s-1AIO\s0 (\fInot\fR \f(CWaio(7)\fR but \f(CWio_submit(2)\fR) event interface available in post\-4.18 kernels (but libev |
|
|
711 | only tries to use it in 4.19+). |
|
|
712 | .Sp |
|
|
713 | This is another Linux train wreck of an event interface. |
|
|
714 | .Sp |
|
|
715 | If this backend works for you (as of this writing, it was very |
|
|
716 | experimental), it is the best event interface available on Linux and might |
|
|
717 | be well worth enabling it \- if it isn't available in your kernel this will |
|
|
718 | be detected and this backend will be skipped. |
|
|
719 | .Sp |
|
|
720 | This backend can batch oneshot requests and supports a user-space ring |
|
|
721 | buffer to receive events. It also doesn't suffer from most of the design |
|
|
722 | problems of epoll (such as not being able to remove event sources from |
|
|
723 | the epoll set), and generally sounds too good to be true. Because, this |
|
|
724 | being the Linux kernel, of course it suffers from a whole new set of |
|
|
725 | limitations, forcing you to fall back to epoll, inheriting all its design |
|
|
726 | issues. |
|
|
727 | .Sp |
|
|
728 | For one, it is not easily embeddable (but probably could be done using |
|
|
729 | an event fd at some extra overhead). It also is subject to a system wide |
|
|
730 | limit that can be configured in \fI/proc/sys/fs/aio\-max\-nr\fR. If no \s-1AIO\s0 |
|
|
731 | requests are left, this backend will be skipped during initialisation, and |
|
|
732 | will switch to epoll when the loop is active. |
|
|
733 | .Sp |
|
|
734 | Most problematic in practice, however, is that not all file descriptors |
|
|
735 | work with it. For example, in Linux 5.1, \s-1TCP\s0 sockets, pipes, event fds, |
|
|
736 | files, \fI/dev/null\fR and many others are supported, but ttys do not work |
|
|
737 | properly (a known bug that the kernel developers don't care about, see |
|
|
738 | <https://lore.kernel.org/patchwork/patch/1047453/>), so this is not |
|
|
739 | (yet?) a generic event polling interface. |
|
|
740 | .Sp |
|
|
741 | Overall, it seems the Linux developers just don't want it to have a |
|
|
742 | generic event handling mechanism other than \f(CW\*(C`select\*(C'\fR or \f(CW\*(C`poll\*(C'\fR. |
|
|
743 | .Sp |
|
|
744 | To work around all these problem, the current version of libev uses its |
|
|
745 | epoll backend as a fallback for file descriptor types that do not work. Or |
|
|
746 | falls back completely to epoll if the kernel acts up. |
654 | .Sp |
747 | .Sp |
655 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
748 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
656 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
749 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
657 | .ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 |
750 | .ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 |
658 | .el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 |
751 | .el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 |
659 | .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" |
752 | .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" |
660 | Kqueue deserves special mention, as at the time of this writing, it |
753 | Kqueue deserves special mention, as at the time this backend was |
661 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
754 | implemented, it was broken on all BSDs except NetBSD (usually it doesn't |
662 | with anything but sockets and pipes, except on Darwin, where of course |
755 | work reliably with anything but sockets and pipes, except on Darwin, |
663 | it's completely useless). Unlike epoll, however, whose brokenness |
756 | where of course it's completely useless). Unlike epoll, however, whose |
664 | is by design, these kqueue bugs can (and eventually will) be fixed |
757 | brokenness is by design, these kqueue bugs can be (and mostly have been) |
665 | without \s-1API\s0 changes to existing programs. For this reason it's not being |
758 | fixed without \s-1API\s0 changes to existing programs. For this reason it's not |
666 | \&\*(L"auto-detected\*(R" unless you explicitly specify it in the flags (i.e. using |
759 | being \*(L"auto-detected\*(R" on all platforms unless you explicitly specify it |
667 | \&\f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR) or libev was compiled on a known-to-be-good (\-enough) |
760 | in the flags (i.e. using \f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR) or libev was compiled on a |
668 | system like NetBSD. |
761 | known-to-be-good (\-enough) system like NetBSD. |
669 | .Sp |
762 | .Sp |
670 | You still can embed kqueue into a normal poll or select backend and use it |
763 | You still can embed kqueue into a normal poll or select backend and use it |
671 | only for sockets (after having made sure that sockets work with kqueue on |
764 | only for sockets (after having made sure that sockets work with kqueue on |
672 | the target platform). See \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
765 | the target platform). See \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
673 | .Sp |
766 | .Sp |
674 | It scales in the same way as the epoll backend, but the interface to the |
767 | It scales in the same way as the epoll backend, but the interface to the |
675 | kernel is more efficient (which says nothing about its actual speed, of |
768 | kernel is more efficient (which says nothing about its actual speed, of |
676 | course). While stopping, setting and starting an I/O watcher does never |
769 | course). While stopping, setting and starting an I/O watcher does never |
677 | cause an extra system call as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to |
770 | cause an extra system call as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to |
678 | two event changes per incident. Support for \f(CW\*(C`fork ()\*(C'\fR is very bad (but |
771 | two event changes per incident. Support for \f(CW\*(C`fork ()\*(C'\fR is very bad (you |
679 | sane, unlike epoll) and it drops fds silently in similarly hard-to-detect |
772 | might have to leak fds on fork, but it's more sane than epoll) and it |
680 | cases |
773 | drops fds silently in similarly hard-to-detect cases. |
681 | .Sp |
774 | .Sp |
682 | This backend usually performs well under most conditions. |
775 | This backend usually performs well under most conditions. |
683 | .Sp |
776 | .Sp |
684 | While nominally embeddable in other event loops, this doesn't work |
777 | While nominally embeddable in other event loops, this doesn't work |
685 | everywhere, so you might need to test for this. And since it is broken |
778 | everywhere, so you might need to test for this. And since it is broken |
686 | almost everywhere, you should only use it when you have a lot of sockets |
779 | almost everywhere, you should only use it when you have a lot of sockets |
687 | (for which it usually works), by embedding it into another event loop |
780 | (for which it usually works), by embedding it into another event loop |
688 | (e.g. \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR (but \f(CW\*(C`poll\*(C'\fR is of course |
781 | (e.g. \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR (but \f(CW\*(C`poll\*(C'\fR is of course |
689 | also broken on \s-1OS\s0 X)) and, did I mention it, using it only for sockets. |
782 | also broken on \s-1OS X\s0)) and, did I mention it, using it only for sockets. |
690 | .Sp |
783 | .Sp |
691 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR into an \f(CW\*(C`EVFILT_READ\*(C'\fR kevent with |
784 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR into an \f(CW\*(C`EVFILT_READ\*(C'\fR kevent with |
692 | \&\f(CW\*(C`NOTE_EOF\*(C'\fR, and \f(CW\*(C`EV_WRITE\*(C'\fR into an \f(CW\*(C`EVFILT_WRITE\*(C'\fR kevent with |
785 | \&\f(CW\*(C`NOTE_EOF\*(C'\fR, and \f(CW\*(C`EV_WRITE\*(C'\fR into an \f(CW\*(C`EVFILT_WRITE\*(C'\fR kevent with |
693 | \&\f(CW\*(C`NOTE_EOF\*(C'\fR. |
786 | \&\f(CW\*(C`NOTE_EOF\*(C'\fR. |
694 | .ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 |
787 | .ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 |
… | |
… | |
698 | implementation). According to reports, \f(CW\*(C`/dev/poll\*(C'\fR only supports sockets |
791 | implementation). According to reports, \f(CW\*(C`/dev/poll\*(C'\fR only supports sockets |
699 | and is not embeddable, which would limit the usefulness of this backend |
792 | and is not embeddable, which would limit the usefulness of this backend |
700 | immensely. |
793 | immensely. |
701 | .ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 |
794 | .ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 |
702 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
795 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
703 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
796 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
704 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
797 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
705 | it's really slow, but it still scales very well (O(active_fds)). |
798 | it's really slow, but it still scales very well (O(active_fds)). |
706 | .Sp |
799 | .Sp |
707 | While this backend scales well, it requires one system call per active |
800 | While this backend scales well, it requires one system call per active |
708 | file descriptor per loop iteration. For small and medium numbers of file |
801 | file descriptor per loop iteration. For small and medium numbers of file |
… | |
… | |
714 | among the OS-specific backends (I vastly prefer correctness over speed |
807 | among the OS-specific backends (I vastly prefer correctness over speed |
715 | hacks). |
808 | hacks). |
716 | .Sp |
809 | .Sp |
717 | On the negative side, the interface is \fIbizarre\fR \- so bizarre that |
810 | On the negative side, the interface is \fIbizarre\fR \- so bizarre that |
718 | even sun itself gets it wrong in their code examples: The event polling |
811 | even sun itself gets it wrong in their code examples: The event polling |
719 | function sometimes returning events to the caller even though an error |
812 | function sometimes returns events to the caller even though an error |
720 | occurred, but with no indication whether it has done so or not (yes, it's |
813 | occurred, but with no indication whether it has done so or not (yes, it's |
721 | even documented that way) \- deadly for edge-triggered interfaces where |
814 | even documented that way) \- deadly for edge-triggered interfaces where you |
722 | you absolutely have to know whether an event occurred or not because you |
815 | absolutely have to know whether an event occurred or not because you have |
723 | have to re-arm the watcher. |
816 | to re-arm the watcher. |
724 | .Sp |
817 | .Sp |
725 | Fortunately libev seems to be able to work around these idiocies. |
818 | Fortunately libev seems to be able to work around these idiocies. |
726 | .Sp |
819 | .Sp |
727 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
820 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
728 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
821 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
… | |
… | |
762 | used if available. |
855 | used if available. |
763 | .Sp |
856 | .Sp |
764 | .Vb 1 |
857 | .Vb 1 |
765 | \& struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE); |
858 | \& struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE); |
766 | .Ve |
859 | .Ve |
|
|
860 | .Sp |
|
|
861 | Example: Similarly, on linux, you mgiht want to take advantage of the |
|
|
862 | linux aio backend if possible, but fall back to something else if that |
|
|
863 | isn't available. |
|
|
864 | .Sp |
|
|
865 | .Vb 1 |
|
|
866 | \& struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_LINUXAIO); |
|
|
867 | .Ve |
767 | .RE |
868 | .RE |
768 | .IP "ev_loop_destroy (loop)" 4 |
869 | .IP "ev_loop_destroy (loop)" 4 |
769 | .IX Item "ev_loop_destroy (loop)" |
870 | .IX Item "ev_loop_destroy (loop)" |
770 | Destroys an event loop object (frees all memory and kernel state |
871 | Destroys an event loop object (frees all memory and kernel state |
771 | etc.). None of the active event watchers will be stopped in the normal |
872 | etc.). None of the active event watchers will be stopped in the normal |
… | |
… | |
787 | except in the rare occasion where you really need to free its resources. |
888 | except in the rare occasion where you really need to free its resources. |
788 | If you need dynamically allocated loops it is better to use \f(CW\*(C`ev_loop_new\*(C'\fR |
889 | If you need dynamically allocated loops it is better to use \f(CW\*(C`ev_loop_new\*(C'\fR |
789 | and \f(CW\*(C`ev_loop_destroy\*(C'\fR. |
890 | and \f(CW\*(C`ev_loop_destroy\*(C'\fR. |
790 | .IP "ev_loop_fork (loop)" 4 |
891 | .IP "ev_loop_fork (loop)" 4 |
791 | .IX Item "ev_loop_fork (loop)" |
892 | .IX Item "ev_loop_fork (loop)" |
792 | This function sets a flag that causes subsequent \f(CW\*(C`ev_run\*(C'\fR iterations to |
893 | This function sets a flag that causes subsequent \f(CW\*(C`ev_run\*(C'\fR iterations |
793 | reinitialise the kernel state for backends that have one. Despite the |
894 | to reinitialise the kernel state for backends that have one. Despite |
794 | name, you can call it anytime, but it makes most sense after forking, in |
895 | the name, you can call it anytime you are allowed to start or stop |
795 | the child process. You \fImust\fR call it (or use \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR) in the |
896 | watchers (except inside an \f(CW\*(C`ev_prepare\*(C'\fR callback), but it makes most |
796 | child before resuming or calling \f(CW\*(C`ev_run\*(C'\fR. |
897 | sense after forking, in the child process. You \fImust\fR call it (or use |
|
|
898 | \&\f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR) in the child before resuming or calling \f(CW\*(C`ev_run\*(C'\fR. |
797 | .Sp |
899 | .Sp |
|
|
900 | In addition, if you want to reuse a loop (via this function or |
|
|
901 | \&\f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR), you \fIalso\fR have to ignore \f(CW\*(C`SIGPIPE\*(C'\fR. |
|
|
902 | .Sp |
798 | Again, you \fIhave\fR to call it on \fIany\fR loop that you want to re-use after |
903 | Again, you \fIhave\fR to call it on \fIany\fR loop that you want to re-use after |
799 | a fork, \fIeven if you do not plan to use the loop in the parent\fR. This is |
904 | a fork, \fIeven if you do not plan to use the loop in the parent\fR. This is |
800 | because some kernel interfaces *cough* \fIkqueue\fR *cough* do funny things |
905 | because some kernel interfaces *cough* \fIkqueue\fR *cough* do funny things |
801 | during fork. |
906 | during fork. |
802 | .Sp |
907 | .Sp |
803 | On the other hand, you only need to call this function in the child |
908 | On the other hand, you only need to call this function in the child |
… | |
… | |
897 | given loop other than \f(CW\*(C`ev_resume\*(C'\fR, and you \fBmust not\fR call \f(CW\*(C`ev_resume\*(C'\fR |
1002 | given loop other than \f(CW\*(C`ev_resume\*(C'\fR, and you \fBmust not\fR call \f(CW\*(C`ev_resume\*(C'\fR |
898 | without a previous call to \f(CW\*(C`ev_suspend\*(C'\fR. |
1003 | without a previous call to \f(CW\*(C`ev_suspend\*(C'\fR. |
899 | .Sp |
1004 | .Sp |
900 | Calling \f(CW\*(C`ev_suspend\*(C'\fR/\f(CW\*(C`ev_resume\*(C'\fR has the side effect of updating the |
1005 | Calling \f(CW\*(C`ev_suspend\*(C'\fR/\f(CW\*(C`ev_resume\*(C'\fR has the side effect of updating the |
901 | event loop time (see \f(CW\*(C`ev_now_update\*(C'\fR). |
1006 | event loop time (see \f(CW\*(C`ev_now_update\*(C'\fR). |
902 | .IP "ev_run (loop, int flags)" 4 |
1007 | .IP "bool ev_run (loop, int flags)" 4 |
903 | .IX Item "ev_run (loop, int flags)" |
1008 | .IX Item "bool ev_run (loop, int flags)" |
904 | Finally, this is it, the event handler. This function usually is called |
1009 | Finally, this is it, the event handler. This function usually is called |
905 | after you have initialised all your watchers and you want to start |
1010 | after you have initialised all your watchers and you want to start |
906 | handling events. It will ask the operating system for any new events, call |
1011 | handling events. It will ask the operating system for any new events, call |
907 | the watcher callbacks, an then repeat the whole process indefinitely: This |
1012 | the watcher callbacks, and then repeat the whole process indefinitely: This |
908 | is why event loops are called \fIloops\fR. |
1013 | is why event loops are called \fIloops\fR. |
909 | .Sp |
1014 | .Sp |
910 | If the flags argument is specified as \f(CW0\fR, it will keep handling events |
1015 | If the flags argument is specified as \f(CW0\fR, it will keep handling events |
911 | until either no event watchers are active anymore or \f(CW\*(C`ev_break\*(C'\fR was |
1016 | until either no event watchers are active anymore or \f(CW\*(C`ev_break\*(C'\fR was |
912 | called. |
1017 | called. |
|
|
1018 | .Sp |
|
|
1019 | The return value is false if there are no more active watchers (which |
|
|
1020 | usually means \*(L"all jobs done\*(R" or \*(L"deadlock\*(R"), and true in all other cases |
|
|
1021 | (which usually means " you should call \f(CW\*(C`ev_run\*(C'\fR again"). |
913 | .Sp |
1022 | .Sp |
914 | Please note that an explicit \f(CW\*(C`ev_break\*(C'\fR is usually better than |
1023 | Please note that an explicit \f(CW\*(C`ev_break\*(C'\fR is usually better than |
915 | relying on all watchers to be stopped when deciding when a program has |
1024 | relying on all watchers to be stopped when deciding when a program has |
916 | finished (especially in interactive programs), but having a program |
1025 | finished (especially in interactive programs), but having a program |
917 | that automatically loops as long as it has to and no longer by virtue |
1026 | that automatically loops as long as it has to and no longer by virtue |
918 | of relying on its watchers stopping correctly, that is truly a thing of |
1027 | of relying on its watchers stopping correctly, that is truly a thing of |
919 | beauty. |
1028 | beauty. |
920 | .Sp |
1029 | .Sp |
921 | This function is also \fImostly\fR exception-safe \- you can break out of |
1030 | This function is \fImostly\fR exception-safe \- you can break out of a |
922 | a \f(CW\*(C`ev_run\*(C'\fR call by calling \f(CW\*(C`longjmp\*(C'\fR in a callback, throwing a \*(C+ |
1031 | \&\f(CW\*(C`ev_run\*(C'\fR call by calling \f(CW\*(C`longjmp\*(C'\fR in a callback, throwing a \*(C+ |
923 | exception and so on. This does not decrement the \f(CW\*(C`ev_depth\*(C'\fR value, nor |
1032 | exception and so on. This does not decrement the \f(CW\*(C`ev_depth\*(C'\fR value, nor |
924 | will it clear any outstanding \f(CW\*(C`EVBREAK_ONE\*(C'\fR breaks. |
1033 | will it clear any outstanding \f(CW\*(C`EVBREAK_ONE\*(C'\fR breaks. |
925 | .Sp |
1034 | .Sp |
926 | A flags value of \f(CW\*(C`EVRUN_NOWAIT\*(C'\fR will look for new events, will handle |
1035 | A flags value of \f(CW\*(C`EVRUN_NOWAIT\*(C'\fR will look for new events, will handle |
927 | those events and any already outstanding ones, but will not wait and |
1036 | those events and any already outstanding ones, but will not wait and |
… | |
… | |
939 | This is useful if you are waiting for some external event in conjunction |
1048 | This is useful if you are waiting for some external event in conjunction |
940 | with something not expressible using other libev watchers (i.e. "roll your |
1049 | with something not expressible using other libev watchers (i.e. "roll your |
941 | own \f(CW\*(C`ev_run\*(C'\fR"). However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is |
1050 | own \f(CW\*(C`ev_run\*(C'\fR"). However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is |
942 | usually a better approach for this kind of thing. |
1051 | usually a better approach for this kind of thing. |
943 | .Sp |
1052 | .Sp |
944 | Here are the gory details of what \f(CW\*(C`ev_run\*(C'\fR does: |
1053 | Here are the gory details of what \f(CW\*(C`ev_run\*(C'\fR does (this is for your |
|
|
1054 | understanding, not a guarantee that things will work exactly like this in |
|
|
1055 | future versions): |
945 | .Sp |
1056 | .Sp |
946 | .Vb 10 |
1057 | .Vb 10 |
947 | \& \- Increment loop depth. |
1058 | \& \- Increment loop depth. |
948 | \& \- Reset the ev_break status. |
1059 | \& \- Reset the ev_break status. |
949 | \& \- Before the first iteration, call any pending watchers. |
1060 | \& \- Before the first iteration, call any pending watchers. |
… | |
… | |
985 | .Sp |
1096 | .Sp |
986 | .Vb 4 |
1097 | .Vb 4 |
987 | \& ... queue jobs here, make sure they register event watchers as long |
1098 | \& ... queue jobs here, make sure they register event watchers as long |
988 | \& ... as they still have work to do (even an idle watcher will do..) |
1099 | \& ... as they still have work to do (even an idle watcher will do..) |
989 | \& ev_run (my_loop, 0); |
1100 | \& ev_run (my_loop, 0); |
990 | \& ... jobs done or somebody called unloop. yeah! |
1101 | \& ... jobs done or somebody called break. yeah! |
991 | .Ve |
1102 | .Ve |
992 | .IP "ev_break (loop, how)" 4 |
1103 | .IP "ev_break (loop, how)" 4 |
993 | .IX Item "ev_break (loop, how)" |
1104 | .IX Item "ev_break (loop, how)" |
994 | Can be used to make a call to \f(CW\*(C`ev_run\*(C'\fR return early (but only after it |
1105 | Can be used to make a call to \f(CW\*(C`ev_run\*(C'\fR return early (but only after it |
995 | has processed all outstanding events). The \f(CW\*(C`how\*(C'\fR argument must be either |
1106 | has processed all outstanding events). The \f(CW\*(C`how\*(C'\fR argument must be either |
… | |
… | |
1064 | overhead for the actual polling but can deliver many events at once. |
1175 | overhead for the actual polling but can deliver many events at once. |
1065 | .Sp |
1176 | .Sp |
1066 | By setting a higher \fIio collect interval\fR you allow libev to spend more |
1177 | By setting a higher \fIio collect interval\fR you allow libev to spend more |
1067 | time collecting I/O events, so you can handle more events per iteration, |
1178 | time collecting I/O events, so you can handle more events per iteration, |
1068 | at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and |
1179 | at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and |
1069 | \&\f(CW\*(C`ev_timer\*(C'\fR) will be not affected. Setting this to a non-null value will |
1180 | \&\f(CW\*(C`ev_timer\*(C'\fR) will not be affected. Setting this to a non-null value will |
1070 | introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations. The |
1181 | introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations. The |
1071 | sleep time ensures that libev will not poll for I/O events more often then |
1182 | sleep time ensures that libev will not poll for I/O events more often then |
1072 | once per this interval, on average. |
1183 | once per this interval, on average (as long as the host time resolution is |
|
|
1184 | good enough). |
1073 | .Sp |
1185 | .Sp |
1074 | Likewise, by setting a higher \fItimeout collect interval\fR you allow libev |
1186 | Likewise, by setting a higher \fItimeout collect interval\fR you allow libev |
1075 | to spend more time collecting timeouts, at the expense of increased |
1187 | to spend more time collecting timeouts, at the expense of increased |
1076 | latency/jitter/inexactness (the watcher callback will be called |
1188 | latency/jitter/inexactness (the watcher callback will be called |
1077 | later). \f(CW\*(C`ev_io\*(C'\fR watchers will not be affected. Setting this to a non-null |
1189 | later). \f(CW\*(C`ev_io\*(C'\fR watchers will not be affected. Setting this to a non-null |
… | |
… | |
1121 | this callback instead. This is useful, for example, when you want to |
1233 | this callback instead. This is useful, for example, when you want to |
1122 | invoke the actual watchers inside another context (another thread etc.). |
1234 | invoke the actual watchers inside another context (another thread etc.). |
1123 | .Sp |
1235 | .Sp |
1124 | If you want to reset the callback, use \f(CW\*(C`ev_invoke_pending\*(C'\fR as new |
1236 | If you want to reset the callback, use \f(CW\*(C`ev_invoke_pending\*(C'\fR as new |
1125 | callback. |
1237 | callback. |
1126 | .IP "ev_set_loop_release_cb (loop, void (*release)(\s-1EV_P\s0), void (*acquire)(\s-1EV_P\s0))" 4 |
1238 | .IP "ev_set_loop_release_cb (loop, void (*release)(\s-1EV_P\s0) throw (), void (*acquire)(\s-1EV_P\s0) throw ())" 4 |
1127 | .IX Item "ev_set_loop_release_cb (loop, void (*release)(EV_P), void (*acquire)(EV_P))" |
1239 | .IX Item "ev_set_loop_release_cb (loop, void (*release)(EV_P) throw (), void (*acquire)(EV_P) throw ())" |
1128 | Sometimes you want to share the same loop between multiple threads. This |
1240 | Sometimes you want to share the same loop between multiple threads. This |
1129 | can be done relatively simply by putting mutex_lock/unlock calls around |
1241 | can be done relatively simply by putting mutex_lock/unlock calls around |
1130 | each call to a libev function. |
1242 | each call to a libev function. |
1131 | .Sp |
1243 | .Sp |
1132 | However, \f(CW\*(C`ev_run\*(C'\fR can run an indefinite time, so it is not feasible |
1244 | However, \f(CW\*(C`ev_run\*(C'\fR can run an indefinite time, so it is not feasible |
1133 | to wait for it to return. One way around this is to wake up the event |
1245 | to wait for it to return. One way around this is to wake up the event |
1134 | loop via \f(CW\*(C`ev_break\*(C'\fR and \f(CW\*(C`av_async_send\*(C'\fR, another way is to set these |
1246 | loop via \f(CW\*(C`ev_break\*(C'\fR and \f(CW\*(C`ev_async_send\*(C'\fR, another way is to set these |
1135 | \&\fIrelease\fR and \fIacquire\fR callbacks on the loop. |
1247 | \&\fIrelease\fR and \fIacquire\fR callbacks on the loop. |
1136 | .Sp |
1248 | .Sp |
1137 | When set, then \f(CW\*(C`release\*(C'\fR will be called just before the thread is |
1249 | When set, then \f(CW\*(C`release\*(C'\fR will be called just before the thread is |
1138 | suspended waiting for new events, and \f(CW\*(C`acquire\*(C'\fR is called just |
1250 | suspended waiting for new events, and \f(CW\*(C`acquire\*(C'\fR is called just |
1139 | afterwards. |
1251 | afterwards. |
… | |
… | |
1280 | .PD 0 |
1392 | .PD 0 |
1281 | .ie n .IP """EV_CHECK""" 4 |
1393 | .ie n .IP """EV_CHECK""" 4 |
1282 | .el .IP "\f(CWEV_CHECK\fR" 4 |
1394 | .el .IP "\f(CWEV_CHECK\fR" 4 |
1283 | .IX Item "EV_CHECK" |
1395 | .IX Item "EV_CHECK" |
1284 | .PD |
1396 | .PD |
1285 | All \f(CW\*(C`ev_prepare\*(C'\fR watchers are invoked just \fIbefore\fR \f(CW\*(C`ev_run\*(C'\fR starts |
1397 | All \f(CW\*(C`ev_prepare\*(C'\fR watchers are invoked just \fIbefore\fR \f(CW\*(C`ev_run\*(C'\fR starts to |
1286 | to gather new events, and all \f(CW\*(C`ev_check\*(C'\fR watchers are invoked just after |
1398 | gather new events, and all \f(CW\*(C`ev_check\*(C'\fR watchers are queued (not invoked) |
1287 | \&\f(CW\*(C`ev_run\*(C'\fR has gathered them, but before it invokes any callbacks for any |
1399 | just after \f(CW\*(C`ev_run\*(C'\fR has gathered them, but before it queues any callbacks |
|
|
1400 | for any received events. That means \f(CW\*(C`ev_prepare\*(C'\fR watchers are the last |
|
|
1401 | watchers invoked before the event loop sleeps or polls for new events, and |
|
|
1402 | \&\f(CW\*(C`ev_check\*(C'\fR watchers will be invoked before any other watchers of the same |
|
|
1403 | or lower priority within an event loop iteration. |
|
|
1404 | .Sp |
1288 | received events. Callbacks of both watcher types can start and stop as |
1405 | Callbacks of both watcher types can start and stop as many watchers as |
1289 | many watchers as they want, and all of them will be taken into account |
1406 | they want, and all of them will be taken into account (for example, a |
1290 | (for example, a \f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep |
1407 | \&\f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep \f(CW\*(C`ev_run\*(C'\fR from |
1291 | \&\f(CW\*(C`ev_run\*(C'\fR from blocking). |
1408 | blocking). |
1292 | .ie n .IP """EV_EMBED""" 4 |
1409 | .ie n .IP """EV_EMBED""" 4 |
1293 | .el .IP "\f(CWEV_EMBED\fR" 4 |
1410 | .el .IP "\f(CWEV_EMBED\fR" 4 |
1294 | .IX Item "EV_EMBED" |
1411 | .IX Item "EV_EMBED" |
1295 | The embedded event loop specified in the \f(CW\*(C`ev_embed\*(C'\fR watcher needs attention. |
1412 | The embedded event loop specified in the \f(CW\*(C`ev_embed\*(C'\fR watcher needs attention. |
1296 | .ie n .IP """EV_FORK""" 4 |
1413 | .ie n .IP """EV_FORK""" 4 |
… | |
… | |
1325 | bug in your program. |
1442 | bug in your program. |
1326 | .Sp |
1443 | .Sp |
1327 | Libev will usually signal a few \*(L"dummy\*(R" events together with an error, for |
1444 | Libev will usually signal a few \*(L"dummy\*(R" events together with an error, for |
1328 | example it might indicate that a fd is readable or writable, and if your |
1445 | example it might indicate that a fd is readable or writable, and if your |
1329 | callbacks is well-written it can just attempt the operation and cope with |
1446 | callbacks is well-written it can just attempt the operation and cope with |
1330 | the error from \fIread()\fR or \fIwrite()\fR. This will not work in multi-threaded |
1447 | the error from \fBread()\fR or \fBwrite()\fR. This will not work in multi-threaded |
1331 | programs, though, as the fd could already be closed and reused for another |
1448 | programs, though, as the fd could already be closed and reused for another |
1332 | thing, so beware. |
1449 | thing, so beware. |
1333 | .SS "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0" |
1450 | .SS "\s-1GENERIC WATCHER FUNCTIONS\s0" |
1334 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
1451 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
1335 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
1452 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
1336 | .el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 |
1453 | .el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 |
1337 | .IX Item "ev_init (ev_TYPE *watcher, callback)" |
1454 | .IX Item "ev_init (ev_TYPE *watcher, callback)" |
1338 | This macro initialises the generic portion of a watcher. The contents |
1455 | This macro initialises the generic portion of a watcher. The contents |
… | |
… | |
1417 | make sure the watcher is available to libev (e.g. you cannot \f(CW\*(C`free ()\*(C'\fR |
1534 | make sure the watcher is available to libev (e.g. you cannot \f(CW\*(C`free ()\*(C'\fR |
1418 | it). |
1535 | it). |
1419 | .IP "callback ev_cb (ev_TYPE *watcher)" 4 |
1536 | .IP "callback ev_cb (ev_TYPE *watcher)" 4 |
1420 | .IX Item "callback ev_cb (ev_TYPE *watcher)" |
1537 | .IX Item "callback ev_cb (ev_TYPE *watcher)" |
1421 | Returns the callback currently set on the watcher. |
1538 | Returns the callback currently set on the watcher. |
1422 | .IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 |
1539 | .IP "ev_set_cb (ev_TYPE *watcher, callback)" 4 |
1423 | .IX Item "ev_cb_set (ev_TYPE *watcher, callback)" |
1540 | .IX Item "ev_set_cb (ev_TYPE *watcher, callback)" |
1424 | Change the callback. You can change the callback at virtually any time |
1541 | Change the callback. You can change the callback at virtually any time |
1425 | (modulo threads). |
1542 | (modulo threads). |
1426 | .IP "ev_set_priority (ev_TYPE *watcher, int priority)" 4 |
1543 | .IP "ev_set_priority (ev_TYPE *watcher, int priority)" 4 |
1427 | .IX Item "ev_set_priority (ev_TYPE *watcher, int priority)" |
1544 | .IX Item "ev_set_priority (ev_TYPE *watcher, int priority)" |
1428 | .PD 0 |
1545 | .PD 0 |
… | |
… | |
1446 | or might not have been clamped to the valid range. |
1563 | or might not have been clamped to the valid range. |
1447 | .Sp |
1564 | .Sp |
1448 | The default priority used by watchers when no priority has been set is |
1565 | The default priority used by watchers when no priority has been set is |
1449 | always \f(CW0\fR, which is supposed to not be too high and not be too low :). |
1566 | always \f(CW0\fR, which is supposed to not be too high and not be too low :). |
1450 | .Sp |
1567 | .Sp |
1451 | See \*(L"\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0\*(R", below, for a more thorough treatment of |
1568 | See \*(L"\s-1WATCHER PRIORITY MODELS\*(R"\s0, below, for a more thorough treatment of |
1452 | priorities. |
1569 | priorities. |
1453 | .IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4 |
1570 | .IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4 |
1454 | .IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)" |
1571 | .IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)" |
1455 | Invoke the \f(CW\*(C`watcher\*(C'\fR with the given \f(CW\*(C`loop\*(C'\fR and \f(CW\*(C`revents\*(C'\fR. Neither |
1572 | Invoke the \f(CW\*(C`watcher\*(C'\fR with the given \f(CW\*(C`loop\*(C'\fR and \f(CW\*(C`revents\*(C'\fR. Neither |
1456 | \&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback |
1573 | \&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback |
… | |
… | |
1476 | not started in the first place. |
1593 | not started in the first place. |
1477 | .Sp |
1594 | .Sp |
1478 | See also \f(CW\*(C`ev_feed_fd_event\*(C'\fR and \f(CW\*(C`ev_feed_signal_event\*(C'\fR for related |
1595 | See also \f(CW\*(C`ev_feed_fd_event\*(C'\fR and \f(CW\*(C`ev_feed_signal_event\*(C'\fR for related |
1479 | functions that do not need a watcher. |
1596 | functions that do not need a watcher. |
1480 | .PP |
1597 | .PP |
1481 | See also the \*(L"\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0\*(R" and \*(L"\s-1BUILDING\s0 \s-1YOUR\s0 |
1598 | See also the \*(L"\s-1ASSOCIATING CUSTOM DATA WITH A WATCHER\*(R"\s0 and \*(L"\s-1BUILDING YOUR |
1482 | \&\s-1OWN\s0 \s-1COMPOSITE\s0 \s-1WATCHERS\s0\*(R" idioms. |
1599 | OWN COMPOSITE WATCHERS\*(R"\s0 idioms. |
1483 | .SS "\s-1WATCHER\s0 \s-1STATES\s0" |
1600 | .SS "\s-1WATCHER STATES\s0" |
1484 | .IX Subsection "WATCHER STATES" |
1601 | .IX Subsection "WATCHER STATES" |
1485 | There are various watcher states mentioned throughout this manual \- |
1602 | There are various watcher states mentioned throughout this manual \- |
1486 | active, pending and so on. In this section these states and the rules to |
1603 | active, pending and so on. In this section these states and the rules to |
1487 | transition between them will be described in more detail \- and while these |
1604 | transition between them will be described in more detail \- and while these |
1488 | rules might look complicated, they usually do \*(L"the right thing\*(R". |
1605 | rules might look complicated, they usually do \*(L"the right thing\*(R". |
1489 | .IP "initialiased" 4 |
1606 | .IP "initialised" 4 |
1490 | .IX Item "initialiased" |
1607 | .IX Item "initialised" |
1491 | Before a watcher can be registered with the event looop it has to be |
1608 | Before a watcher can be registered with the event loop it has to be |
1492 | initialised. This can be done with a call to \f(CW\*(C`ev_TYPE_init\*(C'\fR, or calls to |
1609 | initialised. This can be done with a call to \f(CW\*(C`ev_TYPE_init\*(C'\fR, or calls to |
1493 | \&\f(CW\*(C`ev_init\*(C'\fR followed by the watcher-specific \f(CW\*(C`ev_TYPE_set\*(C'\fR function. |
1610 | \&\f(CW\*(C`ev_init\*(C'\fR followed by the watcher-specific \f(CW\*(C`ev_TYPE_set\*(C'\fR function. |
1494 | .Sp |
1611 | .Sp |
1495 | In this state it is simply some block of memory that is suitable for use |
1612 | In this state it is simply some block of memory that is suitable for |
1496 | in an event loop. It can be moved around, freed, reused etc. at will. |
1613 | use in an event loop. It can be moved around, freed, reused etc. at |
|
|
1614 | will \- as long as you either keep the memory contents intact, or call |
|
|
1615 | \&\f(CW\*(C`ev_TYPE_init\*(C'\fR again. |
1497 | .IP "started/running/active" 4 |
1616 | .IP "started/running/active" 4 |
1498 | .IX Item "started/running/active" |
1617 | .IX Item "started/running/active" |
1499 | Once a watcher has been started with a call to \f(CW\*(C`ev_TYPE_start\*(C'\fR it becomes |
1618 | Once a watcher has been started with a call to \f(CW\*(C`ev_TYPE_start\*(C'\fR it becomes |
1500 | property of the event loop, and is actively waiting for events. While in |
1619 | property of the event loop, and is actively waiting for events. While in |
1501 | this state it cannot be accessed (except in a few documented ways), moved, |
1620 | this state it cannot be accessed (except in a few documented ways), moved, |
… | |
… | |
1526 | latter will clear any pending state the watcher might be in, regardless |
1645 | latter will clear any pending state the watcher might be in, regardless |
1527 | of whether it was active or not, so stopping a watcher explicitly before |
1646 | of whether it was active or not, so stopping a watcher explicitly before |
1528 | freeing it is often a good idea. |
1647 | freeing it is often a good idea. |
1529 | .Sp |
1648 | .Sp |
1530 | While stopped (and not pending) the watcher is essentially in the |
1649 | While stopped (and not pending) the watcher is essentially in the |
1531 | initialised state, that is it can be reused, moved, modified in any way |
1650 | initialised state, that is, it can be reused, moved, modified in any way |
1532 | you wish. |
1651 | you wish (but when you trash the memory block, you need to \f(CW\*(C`ev_TYPE_init\*(C'\fR |
|
|
1652 | it again). |
1533 | .SS "\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0" |
1653 | .SS "\s-1WATCHER PRIORITY MODELS\s0" |
1534 | .IX Subsection "WATCHER PRIORITY MODELS" |
1654 | .IX Subsection "WATCHER PRIORITY MODELS" |
1535 | Many event loops support \fIwatcher priorities\fR, which are usually small |
1655 | Many event loops support \fIwatcher priorities\fR, which are usually small |
1536 | integers that influence the ordering of event callback invocation |
1656 | integers that influence the ordering of event callback invocation |
1537 | between watchers in some way, all else being equal. |
1657 | between watchers in some way, all else being equal. |
1538 | .PP |
1658 | .PP |
… | |
… | |
1683 | But really, best use non-blocking mode. |
1803 | But really, best use non-blocking mode. |
1684 | .PP |
1804 | .PP |
1685 | \fIThe special problem of disappearing file descriptors\fR |
1805 | \fIThe special problem of disappearing file descriptors\fR |
1686 | .IX Subsection "The special problem of disappearing file descriptors" |
1806 | .IX Subsection "The special problem of disappearing file descriptors" |
1687 | .PP |
1807 | .PP |
1688 | Some backends (e.g. kqueue, epoll) need to be told about closing a file |
1808 | Some backends (e.g. kqueue, epoll, linuxaio) need to be told about closing |
1689 | descriptor (either due to calling \f(CW\*(C`close\*(C'\fR explicitly or any other means, |
1809 | a file descriptor (either due to calling \f(CW\*(C`close\*(C'\fR explicitly or any other |
1690 | such as \f(CW\*(C`dup2\*(C'\fR). The reason is that you register interest in some file |
1810 | means, such as \f(CW\*(C`dup2\*(C'\fR). The reason is that you register interest in some |
1691 | descriptor, but when it goes away, the operating system will silently drop |
1811 | file descriptor, but when it goes away, the operating system will silently |
1692 | this interest. If another file descriptor with the same number then is |
1812 | drop this interest. If another file descriptor with the same number then |
1693 | registered with libev, there is no efficient way to see that this is, in |
1813 | is registered with libev, there is no efficient way to see that this is, |
1694 | fact, a different file descriptor. |
1814 | in fact, a different file descriptor. |
1695 | .PP |
1815 | .PP |
1696 | To avoid having to explicitly tell libev about such cases, libev follows |
1816 | To avoid having to explicitly tell libev about such cases, libev follows |
1697 | the following policy: Each time \f(CW\*(C`ev_io_set\*(C'\fR is being called, libev |
1817 | the following policy: Each time \f(CW\*(C`ev_io_set\*(C'\fR is being called, libev |
1698 | will assume that this is potentially a new file descriptor, otherwise |
1818 | will assume that this is potentially a new file descriptor, otherwise |
1699 | it is assumed that the file descriptor stays the same. That means that |
1819 | it is assumed that the file descriptor stays the same. That means that |
… | |
… | |
1736 | wish to read \- you would first have to request some data. |
1856 | wish to read \- you would first have to request some data. |
1737 | .PP |
1857 | .PP |
1738 | Since files are typically not-so-well supported by advanced notification |
1858 | Since files are typically not-so-well supported by advanced notification |
1739 | mechanism, libev tries hard to emulate \s-1POSIX\s0 behaviour with respect |
1859 | mechanism, libev tries hard to emulate \s-1POSIX\s0 behaviour with respect |
1740 | to files, even though you should not use it. The reason for this is |
1860 | to files, even though you should not use it. The reason for this is |
1741 | convenience: sometimes you want to watch \s-1STDIN\s0 or \s-1STDOUT\s0, which is |
1861 | convenience: sometimes you want to watch \s-1STDIN\s0 or \s-1STDOUT,\s0 which is |
1742 | usually a tty, often a pipe, but also sometimes files or special devices |
1862 | usually a tty, often a pipe, but also sometimes files or special devices |
1743 | (for example, \f(CW\*(C`epoll\*(C'\fR on Linux works with \fI/dev/random\fR but not with |
1863 | (for example, \f(CW\*(C`epoll\*(C'\fR on Linux works with \fI/dev/random\fR but not with |
1744 | \&\fI/dev/urandom\fR), and even though the file might better be served with |
1864 | \&\fI/dev/urandom\fR), and even though the file might better be served with |
1745 | asynchronous I/O instead of with non-blocking I/O, it is still useful when |
1865 | asynchronous I/O instead of with non-blocking I/O, it is still useful when |
1746 | it \*(L"just works\*(R" instead of freezing. |
1866 | it \*(L"just works\*(R" instead of freezing. |
1747 | .PP |
1867 | .PP |
1748 | So avoid file descriptors pointing to files when you know it (e.g. use |
1868 | So avoid file descriptors pointing to files when you know it (e.g. use |
1749 | libeio), but use them when it is convenient, e.g. for \s-1STDIN/STDOUT\s0, or |
1869 | libeio), but use them when it is convenient, e.g. for \s-1STDIN/STDOUT,\s0 or |
1750 | when you rarely read from a file instead of from a socket, and want to |
1870 | when you rarely read from a file instead of from a socket, and want to |
1751 | reuse the same code path. |
1871 | reuse the same code path. |
1752 | .PP |
1872 | .PP |
1753 | \fIThe special problem of fork\fR |
1873 | \fIThe special problem of fork\fR |
1754 | .IX Subsection "The special problem of fork" |
1874 | .IX Subsection "The special problem of fork" |
1755 | .PP |
1875 | .PP |
1756 | Some backends (epoll, kqueue) do not support \f(CW\*(C`fork ()\*(C'\fR at all or exhibit |
1876 | Some backends (epoll, kqueue, probably linuxaio) do not support \f(CW\*(C`fork ()\*(C'\fR |
1757 | useless behaviour. Libev fully supports fork, but needs to be told about |
1877 | at all or exhibit useless behaviour. Libev fully supports fork, but needs |
1758 | it in the child if you want to continue to use it in the child. |
1878 | to be told about it in the child if you want to continue to use it in the |
|
|
1879 | child. |
1759 | .PP |
1880 | .PP |
1760 | To support fork in your child processes, you have to call \f(CW\*(C`ev_loop_fork |
1881 | To support fork in your child processes, you have to call \f(CW\*(C`ev_loop_fork |
1761 | ()\*(C'\fR after a fork in the child, enable \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR, or resort to |
1882 | ()\*(C'\fR after a fork in the child, enable \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR, or resort to |
1762 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
1883 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
1763 | .PP |
1884 | .PP |
1764 | \fIThe special problem of \s-1SIGPIPE\s0\fR |
1885 | \fIThe special problem of \s-1SIGPIPE\s0\fR |
1765 | .IX Subsection "The special problem of SIGPIPE" |
1886 | .IX Subsection "The special problem of SIGPIPE" |
1766 | .PP |
1887 | .PP |
1767 | While not really specific to libev, it is easy to forget about \f(CW\*(C`SIGPIPE\*(C'\fR: |
1888 | While not really specific to libev, it is easy to forget about \f(CW\*(C`SIGPIPE\*(C'\fR: |
1768 | when writing to a pipe whose other end has been closed, your program gets |
1889 | when writing to a pipe whose other end has been closed, your program gets |
1769 | sent a \s-1SIGPIPE\s0, which, by default, aborts your program. For most programs |
1890 | sent a \s-1SIGPIPE,\s0 which, by default, aborts your program. For most programs |
1770 | this is sensible behaviour, for daemons, this is usually undesirable. |
1891 | this is sensible behaviour, for daemons, this is usually undesirable. |
1771 | .PP |
1892 | .PP |
1772 | So when you encounter spurious, unexplained daemon exits, make sure you |
1893 | So when you encounter spurious, unexplained daemon exits, make sure you |
1773 | ignore \s-1SIGPIPE\s0 (and maybe make sure you log the exit status of your daemon |
1894 | ignore \s-1SIGPIPE\s0 (and maybe make sure you log the exit status of your daemon |
1774 | somewhere, as that would have given you a big clue). |
1895 | somewhere, as that would have given you a big clue). |
1775 | .PP |
1896 | .PP |
1776 | \fIThe special problem of \fIaccept()\fIing when you can't\fR |
1897 | \fIThe special problem of \f(BIaccept()\fIing when you can't\fR |
1777 | .IX Subsection "The special problem of accept()ing when you can't" |
1898 | .IX Subsection "The special problem of accept()ing when you can't" |
1778 | .PP |
1899 | .PP |
1779 | Many implementations of the \s-1POSIX\s0 \f(CW\*(C`accept\*(C'\fR function (for example, |
1900 | Many implementations of the \s-1POSIX\s0 \f(CW\*(C`accept\*(C'\fR function (for example, |
1780 | found in post\-2004 Linux) have the peculiar behaviour of not removing a |
1901 | found in post\-2004 Linux) have the peculiar behaviour of not removing a |
1781 | connection from the pending queue in all error cases. |
1902 | connection from the pending queue in all error cases. |
… | |
… | |
1865 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1986 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1866 | monotonic clock option helps a lot here). |
1987 | monotonic clock option helps a lot here). |
1867 | .PP |
1988 | .PP |
1868 | The callback is guaranteed to be invoked only \fIafter\fR its timeout has |
1989 | The callback is guaranteed to be invoked only \fIafter\fR its timeout has |
1869 | passed (not \fIat\fR, so on systems with very low-resolution clocks this |
1990 | passed (not \fIat\fR, so on systems with very low-resolution clocks this |
1870 | might introduce a small delay). If multiple timers become ready during the |
1991 | might introduce a small delay, see \*(L"the special problem of being too |
|
|
1992 | early\*(R", below). If multiple timers become ready during the same loop |
1871 | same loop iteration then the ones with earlier time-out values are invoked |
1993 | iteration then the ones with earlier time-out values are invoked before |
1872 | before ones of the same priority with later time-out values (but this is |
1994 | ones of the same priority with later time-out values (but this is no |
1873 | no longer true when a callback calls \f(CW\*(C`ev_run\*(C'\fR recursively). |
1995 | longer true when a callback calls \f(CW\*(C`ev_run\*(C'\fR recursively). |
1874 | .PP |
1996 | .PP |
1875 | \fIBe smart about timeouts\fR |
1997 | \fIBe smart about timeouts\fR |
1876 | .IX Subsection "Be smart about timeouts" |
1998 | .IX Subsection "Be smart about timeouts" |
1877 | .PP |
1999 | .PP |
1878 | Many real-world problems involve some kind of timeout, usually for error |
2000 | Many real-world problems involve some kind of timeout, usually for error |
… | |
… | |
1960 | .Sp |
2082 | .Sp |
1961 | In this case, it would be more efficient to leave the \f(CW\*(C`ev_timer\*(C'\fR alone, |
2083 | In this case, it would be more efficient to leave the \f(CW\*(C`ev_timer\*(C'\fR alone, |
1962 | but remember the time of last activity, and check for a real timeout only |
2084 | but remember the time of last activity, and check for a real timeout only |
1963 | within the callback: |
2085 | within the callback: |
1964 | .Sp |
2086 | .Sp |
1965 | .Vb 1 |
2087 | .Vb 3 |
|
|
2088 | \& ev_tstamp timeout = 60.; |
1966 | \& ev_tstamp last_activity; // time of last activity |
2089 | \& ev_tstamp last_activity; // time of last activity |
|
|
2090 | \& ev_timer timer; |
1967 | \& |
2091 | \& |
1968 | \& static void |
2092 | \& static void |
1969 | \& callback (EV_P_ ev_timer *w, int revents) |
2093 | \& callback (EV_P_ ev_timer *w, int revents) |
1970 | \& { |
2094 | \& { |
1971 | \& ev_tstamp now = ev_now (EV_A); |
2095 | \& // calculate when the timeout would happen |
1972 | \& ev_tstamp timeout = last_activity + 60.; |
2096 | \& ev_tstamp after = last_activity \- ev_now (EV_A) + timeout; |
1973 | \& |
2097 | \& |
1974 | \& // if last_activity + 60. is older than now, we did time out |
2098 | \& // if negative, it means we the timeout already occurred |
1975 | \& if (timeout < now) |
2099 | \& if (after < 0.) |
1976 | \& { |
2100 | \& { |
1977 | \& // timeout occurred, take action |
2101 | \& // timeout occurred, take action |
1978 | \& } |
2102 | \& } |
1979 | \& else |
2103 | \& else |
1980 | \& { |
2104 | \& { |
1981 | \& // callback was invoked, but there was some activity, re\-arm |
2105 | \& // callback was invoked, but there was some recent |
1982 | \& // the watcher to fire in last_activity + 60, which is |
2106 | \& // activity. simply restart the timer to time out |
1983 | \& // guaranteed to be in the future, so "again" is positive: |
2107 | \& // after "after" seconds, which is the earliest time |
1984 | \& w\->repeat = timeout \- now; |
2108 | \& // the timeout can occur. |
|
|
2109 | \& ev_timer_set (w, after, 0.); |
1985 | \& ev_timer_again (EV_A_ w); |
2110 | \& ev_timer_start (EV_A_ w); |
1986 | \& } |
2111 | \& } |
1987 | \& } |
2112 | \& } |
1988 | .Ve |
2113 | .Ve |
1989 | .Sp |
2114 | .Sp |
1990 | To summarise the callback: first calculate the real timeout (defined |
2115 | To summarise the callback: first calculate in how many seconds the |
1991 | as \*(L"60 seconds after the last activity\*(R"), then check if that time has |
2116 | timeout will occur (by calculating the absolute time when it would occur, |
1992 | been reached, which means something \fIdid\fR, in fact, time out. Otherwise |
2117 | \&\f(CW\*(C`last_activity + timeout\*(C'\fR, and subtracting the current time, \f(CW\*(C`ev_now |
1993 | the callback was invoked too early (\f(CW\*(C`timeout\*(C'\fR is in the future), so |
2118 | (EV_A)\*(C'\fR from that). |
1994 | re-schedule the timer to fire at that future time, to see if maybe we have |
|
|
1995 | a timeout then. |
|
|
1996 | .Sp |
2119 | .Sp |
1997 | Note how \f(CW\*(C`ev_timer_again\*(C'\fR is used, taking advantage of the |
2120 | If this value is negative, then we are already past the timeout, i.e. we |
1998 | \&\f(CW\*(C`ev_timer_again\*(C'\fR optimisation when the timer is already running. |
2121 | timed out, and need to do whatever is needed in this case. |
|
|
2122 | .Sp |
|
|
2123 | Otherwise, we now the earliest time at which the timeout would trigger, |
|
|
2124 | and simply start the timer with this timeout value. |
|
|
2125 | .Sp |
|
|
2126 | In other words, each time the callback is invoked it will check whether |
|
|
2127 | the timeout occurred. If not, it will simply reschedule itself to check |
|
|
2128 | again at the earliest time it could time out. Rinse. Repeat. |
1999 | .Sp |
2129 | .Sp |
2000 | This scheme causes more callback invocations (about one every 60 seconds |
2130 | This scheme causes more callback invocations (about one every 60 seconds |
2001 | minus half the average time between activity), but virtually no calls to |
2131 | minus half the average time between activity), but virtually no calls to |
2002 | libev to change the timeout. |
2132 | libev to change the timeout. |
2003 | .Sp |
2133 | .Sp |
2004 | To start the timer, simply initialise the watcher and set \f(CW\*(C`last_activity\*(C'\fR |
2134 | To start the machinery, simply initialise the watcher and set |
2005 | to the current time (meaning we just have some activity :), then call the |
2135 | \&\f(CW\*(C`last_activity\*(C'\fR to the current time (meaning there was some activity just |
2006 | callback, which will \*(L"do the right thing\*(R" and start the timer: |
2136 | now), then call the callback, which will \*(L"do the right thing\*(R" and start |
|
|
2137 | the timer: |
2007 | .Sp |
2138 | .Sp |
2008 | .Vb 3 |
2139 | .Vb 3 |
|
|
2140 | \& last_activity = ev_now (EV_A); |
2009 | \& ev_init (timer, callback); |
2141 | \& ev_init (&timer, callback); |
2010 | \& last_activity = ev_now (loop); |
2142 | \& callback (EV_A_ &timer, 0); |
2011 | \& callback (loop, timer, EV_TIMER); |
|
|
2012 | .Ve |
2143 | .Ve |
2013 | .Sp |
2144 | .Sp |
2014 | And when there is some activity, simply store the current time in |
2145 | When there is some activity, simply store the current time in |
2015 | \&\f(CW\*(C`last_activity\*(C'\fR, no libev calls at all: |
2146 | \&\f(CW\*(C`last_activity\*(C'\fR, no libev calls at all: |
2016 | .Sp |
2147 | .Sp |
2017 | .Vb 1 |
2148 | .Vb 2 |
|
|
2149 | \& if (activity detected) |
2018 | \& last_activity = ev_now (loop); |
2150 | \& last_activity = ev_now (EV_A); |
|
|
2151 | .Ve |
|
|
2152 | .Sp |
|
|
2153 | When your timeout value changes, then the timeout can be changed by simply |
|
|
2154 | providing a new value, stopping the timer and calling the callback, which |
|
|
2155 | will again do the right thing (for example, time out immediately :). |
|
|
2156 | .Sp |
|
|
2157 | .Vb 3 |
|
|
2158 | \& timeout = new_value; |
|
|
2159 | \& ev_timer_stop (EV_A_ &timer); |
|
|
2160 | \& callback (EV_A_ &timer, 0); |
2019 | .Ve |
2161 | .Ve |
2020 | .Sp |
2162 | .Sp |
2021 | This technique is slightly more complex, but in most cases where the |
2163 | This technique is slightly more complex, but in most cases where the |
2022 | time-out is unlikely to be triggered, much more efficient. |
2164 | time-out is unlikely to be triggered, much more efficient. |
2023 | .Sp |
|
|
2024 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
|
|
2025 | callback :) \- just change the timeout and invoke the callback, which will |
|
|
2026 | fix things for you. |
|
|
2027 | .IP "4. Wee, just use a double-linked list for your timeouts." 4 |
2165 | .IP "4. Wee, just use a double-linked list for your timeouts." 4 |
2028 | .IX Item "4. Wee, just use a double-linked list for your timeouts." |
2166 | .IX Item "4. Wee, just use a double-linked list for your timeouts." |
2029 | If there is not one request, but many thousands (millions...), all |
2167 | If there is not one request, but many thousands (millions...), all |
2030 | employing some kind of timeout with the same timeout value, then one can |
2168 | employing some kind of timeout with the same timeout value, then one can |
2031 | do even better: |
2169 | do even better: |
… | |
… | |
2055 | Method #1 is almost always a bad idea, and buys you nothing. Method #4 is |
2193 | Method #1 is almost always a bad idea, and buys you nothing. Method #4 is |
2056 | rather complicated, but extremely efficient, something that really pays |
2194 | rather complicated, but extremely efficient, something that really pays |
2057 | off after the first million or so of active timers, i.e. it's usually |
2195 | off after the first million or so of active timers, i.e. it's usually |
2058 | overkill :) |
2196 | overkill :) |
2059 | .PP |
2197 | .PP |
|
|
2198 | \fIThe special problem of being too early\fR |
|
|
2199 | .IX Subsection "The special problem of being too early" |
|
|
2200 | .PP |
|
|
2201 | If you ask a timer to call your callback after three seconds, then |
|
|
2202 | you expect it to be invoked after three seconds \- but of course, this |
|
|
2203 | cannot be guaranteed to infinite precision. Less obviously, it cannot be |
|
|
2204 | guaranteed to any precision by libev \- imagine somebody suspending the |
|
|
2205 | process with a \s-1STOP\s0 signal for a few hours for example. |
|
|
2206 | .PP |
|
|
2207 | So, libev tries to invoke your callback as soon as possible \fIafter\fR the |
|
|
2208 | delay has occurred, but cannot guarantee this. |
|
|
2209 | .PP |
|
|
2210 | A less obvious failure mode is calling your callback too early: many event |
|
|
2211 | loops compare timestamps with a \*(L"elapsed delay >= requested delay\*(R", but |
|
|
2212 | this can cause your callback to be invoked much earlier than you would |
|
|
2213 | expect. |
|
|
2214 | .PP |
|
|
2215 | To see why, imagine a system with a clock that only offers full second |
|
|
2216 | resolution (think windows if you can't come up with a broken enough \s-1OS\s0 |
|
|
2217 | yourself). If you schedule a one-second timer at the time 500.9, then the |
|
|
2218 | event loop will schedule your timeout to elapse at a system time of 500 |
|
|
2219 | (500.9 truncated to the resolution) + 1, or 501. |
|
|
2220 | .PP |
|
|
2221 | If an event library looks at the timeout 0.1s later, it will see \*(L"501 >= |
|
|
2222 | 501\*(R" and invoke the callback 0.1s after it was started, even though a |
|
|
2223 | one-second delay was requested \- this is being \*(L"too early\*(R", despite best |
|
|
2224 | intentions. |
|
|
2225 | .PP |
|
|
2226 | This is the reason why libev will never invoke the callback if the elapsed |
|
|
2227 | delay equals the requested delay, but only when the elapsed delay is |
|
|
2228 | larger than the requested delay. In the example above, libev would only invoke |
|
|
2229 | the callback at system time 502, or 1.1s after the timer was started. |
|
|
2230 | .PP |
|
|
2231 | So, while libev cannot guarantee that your callback will be invoked |
|
|
2232 | exactly when requested, it \fIcan\fR and \fIdoes\fR guarantee that the requested |
|
|
2233 | delay has actually elapsed, or in other words, it always errs on the \*(L"too |
|
|
2234 | late\*(R" side of things. |
|
|
2235 | .PP |
2060 | \fIThe special problem of time updates\fR |
2236 | \fIThe special problem of time updates\fR |
2061 | .IX Subsection "The special problem of time updates" |
2237 | .IX Subsection "The special problem of time updates" |
2062 | .PP |
2238 | .PP |
2063 | Establishing the current time is a costly operation (it usually takes at |
2239 | Establishing the current time is a costly operation (it usually takes |
2064 | least two system calls): \s-1EV\s0 therefore updates its idea of the current |
2240 | at least one system call): \s-1EV\s0 therefore updates its idea of the current |
2065 | time only before and after \f(CW\*(C`ev_run\*(C'\fR collects new events, which causes a |
2241 | time only before and after \f(CW\*(C`ev_run\*(C'\fR collects new events, which causes a |
2066 | growing difference between \f(CW\*(C`ev_now ()\*(C'\fR and \f(CW\*(C`ev_time ()\*(C'\fR when handling |
2242 | growing difference between \f(CW\*(C`ev_now ()\*(C'\fR and \f(CW\*(C`ev_time ()\*(C'\fR when handling |
2067 | lots of events in one iteration. |
2243 | lots of events in one iteration. |
2068 | .PP |
2244 | .PP |
2069 | The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR |
2245 | The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR |
2070 | time. This is usually the right thing as this timestamp refers to the time |
2246 | time. This is usually the right thing as this timestamp refers to the time |
2071 | of the event triggering whatever timeout you are modifying/starting. If |
2247 | of the event triggering whatever timeout you are modifying/starting. If |
2072 | you suspect event processing to be delayed and you \fIneed\fR to base the |
2248 | you suspect event processing to be delayed and you \fIneed\fR to base the |
2073 | timeout on the current time, use something like this to adjust for this: |
2249 | timeout on the current time, use something like the following to adjust |
|
|
2250 | for it: |
2074 | .PP |
2251 | .PP |
2075 | .Vb 1 |
2252 | .Vb 1 |
2076 | \& ev_timer_set (&timer, after + ev_now () \- ev_time (), 0.); |
2253 | \& ev_timer_set (&timer, after + (ev_time () \- ev_now ()), 0.); |
2077 | .Ve |
2254 | .Ve |
2078 | .PP |
2255 | .PP |
2079 | If the event loop is suspended for a long time, you can also force an |
2256 | If the event loop is suspended for a long time, you can also force an |
2080 | update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update |
2257 | update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update |
2081 | ()\*(C'\fR. |
2258 | ()\*(C'\fR, although that will push the event time of all outstanding events |
|
|
2259 | further into the future. |
|
|
2260 | .PP |
|
|
2261 | \fIThe special problem of unsynchronised clocks\fR |
|
|
2262 | .IX Subsection "The special problem of unsynchronised clocks" |
|
|
2263 | .PP |
|
|
2264 | Modern systems have a variety of clocks \- libev itself uses the normal |
|
|
2265 | \&\*(L"wall clock\*(R" clock and, if available, the monotonic clock (to avoid time |
|
|
2266 | jumps). |
|
|
2267 | .PP |
|
|
2268 | Neither of these clocks is synchronised with each other or any other clock |
|
|
2269 | on the system, so \f(CW\*(C`ev_time ()\*(C'\fR might return a considerably different time |
|
|
2270 | than \f(CW\*(C`gettimeofday ()\*(C'\fR or \f(CW\*(C`time ()\*(C'\fR. On a GNU/Linux system, for example, |
|
|
2271 | a call to \f(CW\*(C`gettimeofday\*(C'\fR might return a second count that is one higher |
|
|
2272 | than a directly following call to \f(CW\*(C`time\*(C'\fR. |
|
|
2273 | .PP |
|
|
2274 | The moral of this is to only compare libev-related timestamps with |
|
|
2275 | \&\f(CW\*(C`ev_time ()\*(C'\fR and \f(CW\*(C`ev_now ()\*(C'\fR, at least if you want better precision than |
|
|
2276 | a second or so. |
|
|
2277 | .PP |
|
|
2278 | One more problem arises due to this lack of synchronisation: if libev uses |
|
|
2279 | the system monotonic clock and you compare timestamps from \f(CW\*(C`ev_time\*(C'\fR |
|
|
2280 | or \f(CW\*(C`ev_now\*(C'\fR from when you started your timer and when your callback is |
|
|
2281 | invoked, you will find that sometimes the callback is a bit \*(L"early\*(R". |
|
|
2282 | .PP |
|
|
2283 | This is because \f(CW\*(C`ev_timer\*(C'\fRs work in real time, not wall clock time, so |
|
|
2284 | libev makes sure your callback is not invoked before the delay happened, |
|
|
2285 | \&\fImeasured according to the real time\fR, not the system clock. |
|
|
2286 | .PP |
|
|
2287 | If your timeouts are based on a physical timescale (e.g. \*(L"time out this |
|
|
2288 | connection after 100 seconds\*(R") then this shouldn't bother you as it is |
|
|
2289 | exactly the right behaviour. |
|
|
2290 | .PP |
|
|
2291 | If you want to compare wall clock/system timestamps to your timers, then |
|
|
2292 | you need to use \f(CW\*(C`ev_periodic\*(C'\fRs, as these are based on the wall clock |
|
|
2293 | time, where your comparisons will always generate correct results. |
2082 | .PP |
2294 | .PP |
2083 | \fIThe special problems of suspended animation\fR |
2295 | \fIThe special problems of suspended animation\fR |
2084 | .IX Subsection "The special problems of suspended animation" |
2296 | .IX Subsection "The special problems of suspended animation" |
2085 | .PP |
2297 | .PP |
2086 | When you leave the server world it is quite customary to hit machines that |
2298 | When you leave the server world it is quite customary to hit machines that |
… | |
… | |
2117 | .IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" |
2329 | .IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" |
2118 | .PD 0 |
2330 | .PD 0 |
2119 | .IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4 |
2331 | .IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4 |
2120 | .IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" |
2332 | .IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" |
2121 | .PD |
2333 | .PD |
2122 | Configure the timer to trigger after \f(CW\*(C`after\*(C'\fR seconds. If \f(CW\*(C`repeat\*(C'\fR |
2334 | Configure the timer to trigger after \f(CW\*(C`after\*(C'\fR seconds (fractional and |
2123 | is \f(CW0.\fR, then it will automatically be stopped once the timeout is |
2335 | negative values are supported). If \f(CW\*(C`repeat\*(C'\fR is \f(CW0.\fR, then it will |
2124 | reached. If it is positive, then the timer will automatically be |
2336 | automatically be stopped once the timeout is reached. If it is positive, |
2125 | configured to trigger again \f(CW\*(C`repeat\*(C'\fR seconds later, again, and again, |
2337 | then the timer will automatically be configured to trigger again \f(CW\*(C`repeat\*(C'\fR |
2126 | until stopped manually. |
2338 | seconds later, again, and again, until stopped manually. |
2127 | .Sp |
2339 | .Sp |
2128 | The timer itself will do a best-effort at avoiding drift, that is, if |
2340 | The timer itself will do a best-effort at avoiding drift, that is, if |
2129 | you configure a timer to trigger every 10 seconds, then it will normally |
2341 | you configure a timer to trigger every 10 seconds, then it will normally |
2130 | trigger at exactly 10 second intervals. If, however, your program cannot |
2342 | trigger at exactly 10 second intervals. If, however, your program cannot |
2131 | keep up with the timer (because it takes longer than those 10 seconds to |
2343 | keep up with the timer (because it takes longer than those 10 seconds to |
2132 | do stuff) the timer will not fire more than once per event loop iteration. |
2344 | do stuff) the timer will not fire more than once per event loop iteration. |
2133 | .IP "ev_timer_again (loop, ev_timer *)" 4 |
2345 | .IP "ev_timer_again (loop, ev_timer *)" 4 |
2134 | .IX Item "ev_timer_again (loop, ev_timer *)" |
2346 | .IX Item "ev_timer_again (loop, ev_timer *)" |
2135 | This will act as if the timer timed out and restart it again if it is |
2347 | This will act as if the timer timed out, and restarts it again if it is |
2136 | repeating. The exact semantics are: |
2348 | repeating. It basically works like calling \f(CW\*(C`ev_timer_stop\*(C'\fR, updating the |
|
|
2349 | timeout to the \f(CW\*(C`repeat\*(C'\fR value and calling \f(CW\*(C`ev_timer_start\*(C'\fR. |
2137 | .Sp |
2350 | .Sp |
|
|
2351 | The exact semantics are as in the following rules, all of which will be |
|
|
2352 | applied to the watcher: |
|
|
2353 | .RS 4 |
2138 | If the timer is pending, its pending status is cleared. |
2354 | .IP "If the timer is pending, the pending status is always cleared." 4 |
2139 | .Sp |
2355 | .IX Item "If the timer is pending, the pending status is always cleared." |
|
|
2356 | .PD 0 |
2140 | If the timer is started but non-repeating, stop it (as if it timed out). |
2357 | .IP "If the timer is started but non-repeating, stop it (as if it timed out, without invoking it)." 4 |
2141 | .Sp |
2358 | .IX Item "If the timer is started but non-repeating, stop it (as if it timed out, without invoking it)." |
2142 | If the timer is repeating, either start it if necessary (with the |
2359 | .ie n .IP "If the timer is repeating, make the ""repeat"" value the new timeout and start the timer, if necessary." 4 |
2143 | \&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value. |
2360 | .el .IP "If the timer is repeating, make the \f(CWrepeat\fR value the new timeout and start the timer, if necessary." 4 |
|
|
2361 | .IX Item "If the timer is repeating, make the repeat value the new timeout and start the timer, if necessary." |
|
|
2362 | .RE |
|
|
2363 | .RS 4 |
|
|
2364 | .PD |
2144 | .Sp |
2365 | .Sp |
2145 | This sounds a bit complicated, see \*(L"Be smart about timeouts\*(R", above, for a |
2366 | This sounds a bit complicated, see \*(L"Be smart about timeouts\*(R", above, for a |
2146 | usage example. |
2367 | usage example. |
|
|
2368 | .RE |
2147 | .IP "ev_tstamp ev_timer_remaining (loop, ev_timer *)" 4 |
2369 | .IP "ev_tstamp ev_timer_remaining (loop, ev_timer *)" 4 |
2148 | .IX Item "ev_tstamp ev_timer_remaining (loop, ev_timer *)" |
2370 | .IX Item "ev_tstamp ev_timer_remaining (loop, ev_timer *)" |
2149 | Returns the remaining time until a timer fires. If the timer is active, |
2371 | Returns the remaining time until a timer fires. If the timer is active, |
2150 | then this time is relative to the current event loop time, otherwise it's |
2372 | then this time is relative to the current event loop time, otherwise it's |
2151 | the timeout value currently configured. |
2373 | the timeout value currently configured. |
… | |
… | |
2203 | Periodic watchers are also timers of a kind, but they are very versatile |
2425 | Periodic watchers are also timers of a kind, but they are very versatile |
2204 | (and unfortunately a bit complex). |
2426 | (and unfortunately a bit complex). |
2205 | .PP |
2427 | .PP |
2206 | Unlike \f(CW\*(C`ev_timer\*(C'\fR, periodic watchers are not based on real time (or |
2428 | Unlike \f(CW\*(C`ev_timer\*(C'\fR, periodic watchers are not based on real time (or |
2207 | relative time, the physical time that passes) but on wall clock time |
2429 | relative time, the physical time that passes) but on wall clock time |
2208 | (absolute time, the thing you can read on your calender or clock). The |
2430 | (absolute time, the thing you can read on your calendar or clock). The |
2209 | difference is that wall clock time can run faster or slower than real |
2431 | difference is that wall clock time can run faster or slower than real |
2210 | time, and time jumps are not uncommon (e.g. when you adjust your |
2432 | time, and time jumps are not uncommon (e.g. when you adjust your |
2211 | wrist-watch). |
2433 | wrist-watch). |
2212 | .PP |
2434 | .PP |
2213 | You can tell a periodic watcher to trigger after some specific point |
2435 | You can tell a periodic watcher to trigger after some specific point |
… | |
… | |
2218 | \&\f(CW\*(C`ev_timer\*(C'\fR, which would still trigger roughly 10 seconds after starting |
2440 | \&\f(CW\*(C`ev_timer\*(C'\fR, which would still trigger roughly 10 seconds after starting |
2219 | it, as it uses a relative timeout). |
2441 | it, as it uses a relative timeout). |
2220 | .PP |
2442 | .PP |
2221 | \&\f(CW\*(C`ev_periodic\*(C'\fR watchers can also be used to implement vastly more complex |
2443 | \&\f(CW\*(C`ev_periodic\*(C'\fR watchers can also be used to implement vastly more complex |
2222 | timers, such as triggering an event on each \*(L"midnight, local time\*(R", or |
2444 | timers, such as triggering an event on each \*(L"midnight, local time\*(R", or |
2223 | other complicated rules. This cannot be done with \f(CW\*(C`ev_timer\*(C'\fR watchers, as |
2445 | other complicated rules. This cannot easily be done with \f(CW\*(C`ev_timer\*(C'\fR |
2224 | those cannot react to time jumps. |
2446 | watchers, as those cannot react to time jumps. |
2225 | .PP |
2447 | .PP |
2226 | As with timers, the callback is guaranteed to be invoked only when the |
2448 | As with timers, the callback is guaranteed to be invoked only when the |
2227 | point in time where it is supposed to trigger has passed. If multiple |
2449 | point in time where it is supposed to trigger has passed. If multiple |
2228 | timers become ready during the same loop iteration then the ones with |
2450 | timers become ready during the same loop iteration then the ones with |
2229 | earlier time-out values are invoked before ones with later time-out values |
2451 | earlier time-out values are invoked before ones with later time-out values |
… | |
… | |
2271 | .Sp |
2493 | .Sp |
2272 | Another way to think about it (for the mathematically inclined) is that |
2494 | Another way to think about it (for the mathematically inclined) is that |
2273 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
2495 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
2274 | time where \f(CW\*(C`time = offset (mod interval)\*(C'\fR, regardless of any time jumps. |
2496 | time where \f(CW\*(C`time = offset (mod interval)\*(C'\fR, regardless of any time jumps. |
2275 | .Sp |
2497 | .Sp |
2276 | For numerical stability it is preferable that the \f(CW\*(C`offset\*(C'\fR value is near |
2498 | The \f(CW\*(C`interval\*(C'\fR \fI\s-1MUST\s0\fR be positive, and for numerical stability, the |
2277 | \&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for |
2499 | interval value should be higher than \f(CW\*(C`1/8192\*(C'\fR (which is around 100 |
2278 | this value, and in fact is often specified as zero. |
2500 | microseconds) and \f(CW\*(C`offset\*(C'\fR should be higher than \f(CW0\fR and should have |
|
|
2501 | at most a similar magnitude as the current time (say, within a factor of |
|
|
2502 | ten). Typical values for offset are, in fact, \f(CW0\fR or something between |
|
|
2503 | \&\f(CW0\fR and \f(CW\*(C`interval\*(C'\fR, which is also the recommended range. |
2279 | .Sp |
2504 | .Sp |
2280 | Note also that there is an upper limit to how often a timer can fire (\s-1CPU\s0 |
2505 | Note also that there is an upper limit to how often a timer can fire (\s-1CPU\s0 |
2281 | speed for example), so if \f(CW\*(C`interval\*(C'\fR is very small then timing stability |
2506 | speed for example), so if \f(CW\*(C`interval\*(C'\fR is very small then timing stability |
2282 | will of course deteriorate. Libev itself tries to be exact to be about one |
2507 | will of course deteriorate. Libev itself tries to be exact to be about one |
2283 | millisecond (if the \s-1OS\s0 supports it and the machine is fast enough). |
2508 | millisecond (if the \s-1OS\s0 supports it and the machine is fast enough). |
… | |
… | |
2287 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`offset\*(C'\fR are both being |
2512 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`offset\*(C'\fR are both being |
2288 | ignored. Instead, each time the periodic watcher gets scheduled, the |
2513 | ignored. Instead, each time the periodic watcher gets scheduled, the |
2289 | reschedule callback will be called with the watcher as first, and the |
2514 | reschedule callback will be called with the watcher as first, and the |
2290 | current time as second argument. |
2515 | current time as second argument. |
2291 | .Sp |
2516 | .Sp |
2292 | \&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, ever, |
2517 | \&\s-1NOTE:\s0 \fIThis callback \s-1MUST NOT\s0 stop or destroy any periodic watcher, ever, |
2293 | or make \s-1ANY\s0 other event loop modifications whatsoever, unless explicitly |
2518 | or make \s-1ANY\s0 other event loop modifications whatsoever, unless explicitly |
2294 | allowed by documentation here\fR. |
2519 | allowed by documentation here\fR. |
2295 | .Sp |
2520 | .Sp |
2296 | If you need to stop it, return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop |
2521 | If you need to stop it, return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop |
2297 | it afterwards (e.g. by starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is the |
2522 | it afterwards (e.g. by starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is the |
… | |
… | |
2315 | .Sp |
2540 | .Sp |
2316 | \&\s-1NOTE:\s0 \fIThis callback must always return a time that is higher than or |
2541 | \&\s-1NOTE:\s0 \fIThis callback must always return a time that is higher than or |
2317 | equal to the passed \f(CI\*(C`now\*(C'\fI value\fR. |
2542 | equal to the passed \f(CI\*(C`now\*(C'\fI value\fR. |
2318 | .Sp |
2543 | .Sp |
2319 | This can be used to create very complex timers, such as a timer that |
2544 | This can be used to create very complex timers, such as a timer that |
2320 | triggers on \*(L"next midnight, local time\*(R". To do this, you would calculate the |
2545 | triggers on \*(L"next midnight, local time\*(R". To do this, you would calculate |
2321 | next midnight after \f(CW\*(C`now\*(C'\fR and return the timestamp value for this. How |
2546 | the next midnight after \f(CW\*(C`now\*(C'\fR and return the timestamp value for |
2322 | you do this is, again, up to you (but it is not trivial, which is the main |
2547 | this. Here is a (completely untested, no error checking) example on how to |
2323 | reason I omitted it as an example). |
2548 | do this: |
|
|
2549 | .Sp |
|
|
2550 | .Vb 1 |
|
|
2551 | \& #include <time.h> |
|
|
2552 | \& |
|
|
2553 | \& static ev_tstamp |
|
|
2554 | \& my_rescheduler (ev_periodic *w, ev_tstamp now) |
|
|
2555 | \& { |
|
|
2556 | \& time_t tnow = (time_t)now; |
|
|
2557 | \& struct tm tm; |
|
|
2558 | \& localtime_r (&tnow, &tm); |
|
|
2559 | \& |
|
|
2560 | \& tm.tm_sec = tm.tm_min = tm.tm_hour = 0; // midnight current day |
|
|
2561 | \& ++tm.tm_mday; // midnight next day |
|
|
2562 | \& |
|
|
2563 | \& return mktime (&tm); |
|
|
2564 | \& } |
|
|
2565 | .Ve |
|
|
2566 | .Sp |
|
|
2567 | Note: this code might run into trouble on days that have more then two |
|
|
2568 | midnights (beginning and end). |
2324 | .RE |
2569 | .RE |
2325 | .RS 4 |
2570 | .RS 4 |
2326 | .RE |
2571 | .RE |
2327 | .IP "ev_periodic_again (loop, ev_periodic *)" 4 |
2572 | .IP "ev_periodic_again (loop, ev_periodic *)" 4 |
2328 | .IX Item "ev_periodic_again (loop, ev_periodic *)" |
2573 | .IX Item "ev_periodic_again (loop, ev_periodic *)" |
… | |
… | |
2413 | only within the same loop, i.e. you can watch for \f(CW\*(C`SIGINT\*(C'\fR in your |
2658 | only within the same loop, i.e. you can watch for \f(CW\*(C`SIGINT\*(C'\fR in your |
2414 | default loop and for \f(CW\*(C`SIGIO\*(C'\fR in another loop, but you cannot watch for |
2659 | default loop and for \f(CW\*(C`SIGIO\*(C'\fR in another loop, but you cannot watch for |
2415 | \&\f(CW\*(C`SIGINT\*(C'\fR in both the default loop and another loop at the same time. At |
2660 | \&\f(CW\*(C`SIGINT\*(C'\fR in both the default loop and another loop at the same time. At |
2416 | the moment, \f(CW\*(C`SIGCHLD\*(C'\fR is permanently tied to the default loop. |
2661 | the moment, \f(CW\*(C`SIGCHLD\*(C'\fR is permanently tied to the default loop. |
2417 | .PP |
2662 | .PP |
2418 | When the first watcher gets started will libev actually register something |
2663 | Only after the first watcher for a signal is started will libev actually |
2419 | with the kernel (thus it coexists with your own signal handlers as long as |
2664 | register something with the kernel. It thus coexists with your own signal |
2420 | you don't register any with libev for the same signal). |
2665 | handlers as long as you don't register any with libev for the same signal. |
2421 | .PP |
2666 | .PP |
2422 | If possible and supported, libev will install its handlers with |
2667 | If possible and supported, libev will install its handlers with |
2423 | \&\f(CW\*(C`SA_RESTART\*(C'\fR (or equivalent) behaviour enabled, so system calls should |
2668 | \&\f(CW\*(C`SA_RESTART\*(C'\fR (or equivalent) behaviour enabled, so system calls should |
2424 | not be unduly interrupted. If you have a problem with system calls getting |
2669 | not be unduly interrupted. If you have a problem with system calls getting |
2425 | interrupted by signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher |
2670 | interrupted by signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher |
… | |
… | |
2429 | .IX Subsection "The special problem of inheritance over fork/execve/pthread_create" |
2674 | .IX Subsection "The special problem of inheritance over fork/execve/pthread_create" |
2430 | .PP |
2675 | .PP |
2431 | Both the signal mask (\f(CW\*(C`sigprocmask\*(C'\fR) and the signal disposition |
2676 | Both the signal mask (\f(CW\*(C`sigprocmask\*(C'\fR) and the signal disposition |
2432 | (\f(CW\*(C`sigaction\*(C'\fR) are unspecified after starting a signal watcher (and after |
2677 | (\f(CW\*(C`sigaction\*(C'\fR) are unspecified after starting a signal watcher (and after |
2433 | stopping it again), that is, libev might or might not block the signal, |
2678 | stopping it again), that is, libev might or might not block the signal, |
2434 | and might or might not set or restore the installed signal handler. |
2679 | and might or might not set or restore the installed signal handler (but |
|
|
2680 | see \f(CW\*(C`EVFLAG_NOSIGMASK\*(C'\fR). |
2435 | .PP |
2681 | .PP |
2436 | While this does not matter for the signal disposition (libev never |
2682 | While this does not matter for the signal disposition (libev never |
2437 | sets signals to \f(CW\*(C`SIG_IGN\*(C'\fR, so handlers will be reset to \f(CW\*(C`SIG_DFL\*(C'\fR on |
2683 | sets signals to \f(CW\*(C`SIG_IGN\*(C'\fR, so handlers will be reset to \f(CW\*(C`SIG_DFL\*(C'\fR on |
2438 | \&\f(CW\*(C`execve\*(C'\fR), this matters for the signal mask: many programs do not expect |
2684 | \&\f(CW\*(C`execve\*(C'\fR), this matters for the signal mask: many programs do not expect |
2439 | certain signals to be blocked. |
2685 | certain signals to be blocked. |
… | |
… | |
2485 | The signal the watcher watches out for. |
2731 | The signal the watcher watches out for. |
2486 | .PP |
2732 | .PP |
2487 | \fIExamples\fR |
2733 | \fIExamples\fR |
2488 | .IX Subsection "Examples" |
2734 | .IX Subsection "Examples" |
2489 | .PP |
2735 | .PP |
2490 | Example: Try to exit cleanly on \s-1SIGINT\s0. |
2736 | Example: Try to exit cleanly on \s-1SIGINT.\s0 |
2491 | .PP |
2737 | .PP |
2492 | .Vb 5 |
2738 | .Vb 5 |
2493 | \& static void |
2739 | \& static void |
2494 | \& sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2740 | \& sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2495 | \& { |
2741 | \& { |
… | |
… | |
2610 | .ie n .SS """ev_stat"" \- did the file attributes just change?" |
2856 | .ie n .SS """ev_stat"" \- did the file attributes just change?" |
2611 | .el .SS "\f(CWev_stat\fP \- did the file attributes just change?" |
2857 | .el .SS "\f(CWev_stat\fP \- did the file attributes just change?" |
2612 | .IX Subsection "ev_stat - did the file attributes just change?" |
2858 | .IX Subsection "ev_stat - did the file attributes just change?" |
2613 | This watches a file system path for attribute changes. That is, it calls |
2859 | This watches a file system path for attribute changes. That is, it calls |
2614 | \&\f(CW\*(C`stat\*(C'\fR on that path in regular intervals (or when the \s-1OS\s0 says it changed) |
2860 | \&\f(CW\*(C`stat\*(C'\fR on that path in regular intervals (or when the \s-1OS\s0 says it changed) |
2615 | and sees if it changed compared to the last time, invoking the callback if |
2861 | and sees if it changed compared to the last time, invoking the callback |
2616 | it did. |
2862 | if it did. Starting the watcher \f(CW\*(C`stat\*(C'\fR's the file, so only changes that |
|
|
2863 | happen after the watcher has been started will be reported. |
2617 | .PP |
2864 | .PP |
2618 | The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does |
2865 | The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does |
2619 | not exist\*(R" is a status change like any other. The condition \*(L"path does not |
2866 | not exist\*(R" is a status change like any other. The condition \*(L"path does not |
2620 | exist\*(R" (or more correctly \*(L"path cannot be stat'ed\*(R") is signified by the |
2867 | exist\*(R" (or more correctly \*(L"path cannot be stat'ed\*(R") is signified by the |
2621 | \&\f(CW\*(C`st_nlink\*(C'\fR field being zero (which is otherwise always forced to be at |
2868 | \&\f(CW\*(C`st_nlink\*(C'\fR field being zero (which is otherwise always forced to be at |
… | |
… | |
2651 | compilation environment, which means that on systems with large file |
2898 | compilation environment, which means that on systems with large file |
2652 | support disabled by default, you get the 32 bit version of the stat |
2899 | support disabled by default, you get the 32 bit version of the stat |
2653 | structure. When using the library from programs that change the \s-1ABI\s0 to |
2900 | structure. When using the library from programs that change the \s-1ABI\s0 to |
2654 | use 64 bit file offsets the programs will fail. In that case you have to |
2901 | use 64 bit file offsets the programs will fail. In that case you have to |
2655 | compile libev with the same flags to get binary compatibility. This is |
2902 | compile libev with the same flags to get binary compatibility. This is |
2656 | obviously the case with any flags that change the \s-1ABI\s0, but the problem is |
2903 | obviously the case with any flags that change the \s-1ABI,\s0 but the problem is |
2657 | most noticeably displayed with ev_stat and large file support. |
2904 | most noticeably displayed with ev_stat and large file support. |
2658 | .PP |
2905 | .PP |
2659 | The solution for this is to lobby your distribution maker to make large |
2906 | The solution for this is to lobby your distribution maker to make large |
2660 | file interfaces available by default (as e.g. FreeBSD does) and not |
2907 | file interfaces available by default (as e.g. FreeBSD does) and not |
2661 | optional. Libev cannot simply switch on large file support because it has |
2908 | optional. Libev cannot simply switch on large file support because it has |
… | |
… | |
2852 | Apart from keeping your process non-blocking (which is a useful |
3099 | Apart from keeping your process non-blocking (which is a useful |
2853 | effect on its own sometimes), idle watchers are a good place to do |
3100 | effect on its own sometimes), idle watchers are a good place to do |
2854 | \&\*(L"pseudo-background processing\*(R", or delay processing stuff to after the |
3101 | \&\*(L"pseudo-background processing\*(R", or delay processing stuff to after the |
2855 | event loop has handled all outstanding events. |
3102 | event loop has handled all outstanding events. |
2856 | .PP |
3103 | .PP |
|
|
3104 | \fIAbusing an \f(CI\*(C`ev_idle\*(C'\fI watcher for its side-effect\fR |
|
|
3105 | .IX Subsection "Abusing an ev_idle watcher for its side-effect" |
|
|
3106 | .PP |
|
|
3107 | As long as there is at least one active idle watcher, libev will never |
|
|
3108 | sleep unnecessarily. Or in other words, it will loop as fast as possible. |
|
|
3109 | For this to work, the idle watcher doesn't need to be invoked at all \- the |
|
|
3110 | lowest priority will do. |
|
|
3111 | .PP |
|
|
3112 | This mode of operation can be useful together with an \f(CW\*(C`ev_check\*(C'\fR watcher, |
|
|
3113 | to do something on each event loop iteration \- for example to balance load |
|
|
3114 | between different connections. |
|
|
3115 | .PP |
|
|
3116 | See \*(L"Abusing an ev_check watcher for its side-effect\*(R" for a longer |
|
|
3117 | example. |
|
|
3118 | .PP |
2857 | \fIWatcher-Specific Functions and Data Members\fR |
3119 | \fIWatcher-Specific Functions and Data Members\fR |
2858 | .IX Subsection "Watcher-Specific Functions and Data Members" |
3120 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2859 | .IP "ev_idle_init (ev_idle *, callback)" 4 |
3121 | .IP "ev_idle_init (ev_idle *, callback)" 4 |
2860 | .IX Item "ev_idle_init (ev_idle *, callback)" |
3122 | .IX Item "ev_idle_init (ev_idle *, callback)" |
2861 | Initialises and configures the idle watcher \- it has no parameters of any |
3123 | Initialises and configures the idle watcher \- it has no parameters of any |
… | |
… | |
2866 | .IX Subsection "Examples" |
3128 | .IX Subsection "Examples" |
2867 | .PP |
3129 | .PP |
2868 | Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the |
3130 | Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the |
2869 | callback, free it. Also, use no error checking, as usual. |
3131 | callback, free it. Also, use no error checking, as usual. |
2870 | .PP |
3132 | .PP |
2871 | .Vb 7 |
3133 | .Vb 5 |
2872 | \& static void |
3134 | \& static void |
2873 | \& idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
3135 | \& idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
2874 | \& { |
3136 | \& { |
|
|
3137 | \& // stop the watcher |
|
|
3138 | \& ev_idle_stop (loop, w); |
|
|
3139 | \& |
|
|
3140 | \& // now we can free it |
2875 | \& free (w); |
3141 | \& free (w); |
|
|
3142 | \& |
2876 | \& // now do something you wanted to do when the program has |
3143 | \& // now do something you wanted to do when the program has |
2877 | \& // no longer anything immediate to do. |
3144 | \& // no longer anything immediate to do. |
2878 | \& } |
3145 | \& } |
2879 | \& |
3146 | \& |
2880 | \& ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
3147 | \& ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
… | |
… | |
2882 | \& ev_idle_start (loop, idle_watcher); |
3149 | \& ev_idle_start (loop, idle_watcher); |
2883 | .Ve |
3150 | .Ve |
2884 | .ie n .SS """ev_prepare"" and ""ev_check"" \- customise your event loop!" |
3151 | .ie n .SS """ev_prepare"" and ""ev_check"" \- customise your event loop!" |
2885 | .el .SS "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!" |
3152 | .el .SS "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!" |
2886 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
3153 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
2887 | Prepare and check watchers are usually (but not always) used in pairs: |
3154 | Prepare and check watchers are often (but not always) used in pairs: |
2888 | prepare watchers get invoked before the process blocks and check watchers |
3155 | prepare watchers get invoked before the process blocks and check watchers |
2889 | afterwards. |
3156 | afterwards. |
2890 | .PP |
3157 | .PP |
2891 | You \fImust not\fR call \f(CW\*(C`ev_run\*(C'\fR or similar functions that enter |
3158 | You \fImust not\fR call \f(CW\*(C`ev_run\*(C'\fR (or similar functions that enter the |
2892 | the current event loop from either \f(CW\*(C`ev_prepare\*(C'\fR or \f(CW\*(C`ev_check\*(C'\fR |
3159 | current event loop) or \f(CW\*(C`ev_loop_fork\*(C'\fR from either \f(CW\*(C`ev_prepare\*(C'\fR or |
2893 | watchers. Other loops than the current one are fine, however. The |
3160 | \&\f(CW\*(C`ev_check\*(C'\fR watchers. Other loops than the current one are fine, |
2894 | rationale behind this is that you do not need to check for recursion in |
3161 | however. The rationale behind this is that you do not need to check |
2895 | those watchers, i.e. the sequence will always be \f(CW\*(C`ev_prepare\*(C'\fR, blocking, |
3162 | for recursion in those watchers, i.e. the sequence will always be |
2896 | \&\f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each kind they will always be |
3163 | \&\f(CW\*(C`ev_prepare\*(C'\fR, blocking, \f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each |
2897 | called in pairs bracketing the blocking call. |
3164 | kind they will always be called in pairs bracketing the blocking call. |
2898 | .PP |
3165 | .PP |
2899 | Their main purpose is to integrate other event mechanisms into libev and |
3166 | Their main purpose is to integrate other event mechanisms into libev and |
2900 | their use is somewhat advanced. They could be used, for example, to track |
3167 | their use is somewhat advanced. They could be used, for example, to track |
2901 | variable changes, implement your own watchers, integrate net-snmp or a |
3168 | variable changes, implement your own watchers, integrate net-snmp or a |
2902 | coroutine library and lots more. They are also occasionally useful if |
3169 | coroutine library and lots more. They are also occasionally useful if |
… | |
… | |
2920 | with priority higher than or equal to the event loop and one coroutine |
3187 | with priority higher than or equal to the event loop and one coroutine |
2921 | of lower priority, but only once, using idle watchers to keep the event |
3188 | of lower priority, but only once, using idle watchers to keep the event |
2922 | loop from blocking if lower-priority coroutines are active, thus mapping |
3189 | loop from blocking if lower-priority coroutines are active, thus mapping |
2923 | low-priority coroutines to idle/background tasks). |
3190 | low-priority coroutines to idle/background tasks). |
2924 | .PP |
3191 | .PP |
2925 | It is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR) |
3192 | When used for this purpose, it is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers |
2926 | priority, to ensure that they are being run before any other watchers |
3193 | highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR) priority, to ensure that they are being run before |
2927 | after the poll (this doesn't matter for \f(CW\*(C`ev_prepare\*(C'\fR watchers). |
3194 | any other watchers after the poll (this doesn't matter for \f(CW\*(C`ev_prepare\*(C'\fR |
|
|
3195 | watchers). |
2928 | .PP |
3196 | .PP |
2929 | Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers, too) should not |
3197 | Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers, too) should not |
2930 | activate (\*(L"feed\*(R") events into libev. While libev fully supports this, they |
3198 | activate (\*(L"feed\*(R") events into libev. While libev fully supports this, they |
2931 | might get executed before other \f(CW\*(C`ev_check\*(C'\fR watchers did their job. As |
3199 | might get executed before other \f(CW\*(C`ev_check\*(C'\fR watchers did their job. As |
2932 | \&\f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other (non-libev) event |
3200 | \&\f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other (non-libev) event |
2933 | loops those other event loops might be in an unusable state until their |
3201 | loops those other event loops might be in an unusable state until their |
2934 | \&\f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to coexist peacefully with |
3202 | \&\f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to coexist peacefully with |
2935 | others). |
3203 | others). |
|
|
3204 | .PP |
|
|
3205 | \fIAbusing an \f(CI\*(C`ev_check\*(C'\fI watcher for its side-effect\fR |
|
|
3206 | .IX Subsection "Abusing an ev_check watcher for its side-effect" |
|
|
3207 | .PP |
|
|
3208 | \&\f(CW\*(C`ev_check\*(C'\fR (and less often also \f(CW\*(C`ev_prepare\*(C'\fR) watchers can also be |
|
|
3209 | useful because they are called once per event loop iteration. For |
|
|
3210 | example, if you want to handle a large number of connections fairly, you |
|
|
3211 | normally only do a bit of work for each active connection, and if there |
|
|
3212 | is more work to do, you wait for the next event loop iteration, so other |
|
|
3213 | connections have a chance of making progress. |
|
|
3214 | .PP |
|
|
3215 | Using an \f(CW\*(C`ev_check\*(C'\fR watcher is almost enough: it will be called on the |
|
|
3216 | next event loop iteration. However, that isn't as soon as possible \- |
|
|
3217 | without external events, your \f(CW\*(C`ev_check\*(C'\fR watcher will not be invoked. |
|
|
3218 | .PP |
|
|
3219 | This is where \f(CW\*(C`ev_idle\*(C'\fR watchers come in handy \- all you need is a |
|
|
3220 | single global idle watcher that is active as long as you have one active |
|
|
3221 | \&\f(CW\*(C`ev_check\*(C'\fR watcher. The \f(CW\*(C`ev_idle\*(C'\fR watcher makes sure the event loop |
|
|
3222 | will not sleep, and the \f(CW\*(C`ev_check\*(C'\fR watcher makes sure a callback gets |
|
|
3223 | invoked. Neither watcher alone can do that. |
2936 | .PP |
3224 | .PP |
2937 | \fIWatcher-Specific Functions and Data Members\fR |
3225 | \fIWatcher-Specific Functions and Data Members\fR |
2938 | .IX Subsection "Watcher-Specific Functions and Data Members" |
3226 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2939 | .IP "ev_prepare_init (ev_prepare *, callback)" 4 |
3227 | .IP "ev_prepare_init (ev_prepare *, callback)" 4 |
2940 | .IX Item "ev_prepare_init (ev_prepare *, callback)" |
3228 | .IX Item "ev_prepare_init (ev_prepare *, callback)" |
… | |
… | |
3051 | .Ve |
3339 | .Ve |
3052 | .PP |
3340 | .PP |
3053 | Method 4: Do not use a prepare or check watcher because the module you |
3341 | Method 4: Do not use a prepare or check watcher because the module you |
3054 | want to embed is not flexible enough to support it. Instead, you can |
3342 | want to embed is not flexible enough to support it. Instead, you can |
3055 | override their poll function. The drawback with this solution is that the |
3343 | override their poll function. The drawback with this solution is that the |
3056 | main loop is now no longer controllable by \s-1EV\s0. The \f(CW\*(C`Glib::EV\*(C'\fR module uses |
3344 | main loop is now no longer controllable by \s-1EV.\s0 The \f(CW\*(C`Glib::EV\*(C'\fR module uses |
3057 | this approach, effectively embedding \s-1EV\s0 as a client into the horrible |
3345 | this approach, effectively embedding \s-1EV\s0 as a client into the horrible |
3058 | libglib event loop. |
3346 | libglib event loop. |
3059 | .PP |
3347 | .PP |
3060 | .Vb 4 |
3348 | .Vb 4 |
3061 | \& static gint |
3349 | \& static gint |
… | |
… | |
3145 | \fIWatcher-Specific Functions and Data Members\fR |
3433 | \fIWatcher-Specific Functions and Data Members\fR |
3146 | .IX Subsection "Watcher-Specific Functions and Data Members" |
3434 | .IX Subsection "Watcher-Specific Functions and Data Members" |
3147 | .IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
3435 | .IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
3148 | .IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" |
3436 | .IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" |
3149 | .PD 0 |
3437 | .PD 0 |
3150 | .IP "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
3438 | .IP "ev_embed_set (ev_embed *, struct ev_loop *embedded_loop)" 4 |
3151 | .IX Item "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" |
3439 | .IX Item "ev_embed_set (ev_embed *, struct ev_loop *embedded_loop)" |
3152 | .PD |
3440 | .PD |
3153 | Configures the watcher to embed the given loop, which must be |
3441 | Configures the watcher to embed the given loop, which must be |
3154 | embeddable. If the callback is \f(CW0\fR, then \f(CW\*(C`ev_embed_sweep\*(C'\fR will be |
3442 | embeddable. If the callback is \f(CW0\fR, then \f(CW\*(C`ev_embed_sweep\*(C'\fR will be |
3155 | invoked automatically, otherwise it is the responsibility of the callback |
3443 | invoked automatically, otherwise it is the responsibility of the callback |
3156 | to invoke it (it will continue to be called until the sweep has been done, |
3444 | to invoke it (it will continue to be called until the sweep has been done, |
… | |
… | |
3175 | .PP |
3463 | .PP |
3176 | .Vb 3 |
3464 | .Vb 3 |
3177 | \& struct ev_loop *loop_hi = ev_default_init (0); |
3465 | \& struct ev_loop *loop_hi = ev_default_init (0); |
3178 | \& struct ev_loop *loop_lo = 0; |
3466 | \& struct ev_loop *loop_lo = 0; |
3179 | \& ev_embed embed; |
3467 | \& ev_embed embed; |
3180 | \& |
3468 | \& |
3181 | \& // see if there is a chance of getting one that works |
3469 | \& // see if there is a chance of getting one that works |
3182 | \& // (remember that a flags value of 0 means autodetection) |
3470 | \& // (remember that a flags value of 0 means autodetection) |
3183 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3471 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3184 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3472 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3185 | \& : 0; |
3473 | \& : 0; |
… | |
… | |
3201 | .PP |
3489 | .PP |
3202 | .Vb 3 |
3490 | .Vb 3 |
3203 | \& struct ev_loop *loop = ev_default_init (0); |
3491 | \& struct ev_loop *loop = ev_default_init (0); |
3204 | \& struct ev_loop *loop_socket = 0; |
3492 | \& struct ev_loop *loop_socket = 0; |
3205 | \& ev_embed embed; |
3493 | \& ev_embed embed; |
3206 | \& |
3494 | \& |
3207 | \& if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3495 | \& if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3208 | \& if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3496 | \& if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3209 | \& { |
3497 | \& { |
3210 | \& ev_embed_init (&embed, 0, loop_socket); |
3498 | \& ev_embed_init (&embed, 0, loop_socket); |
3211 | \& ev_embed_start (loop, &embed); |
3499 | \& ev_embed_start (loop, &embed); |
… | |
… | |
3219 | .ie n .SS """ev_fork"" \- the audacity to resume the event loop after a fork" |
3507 | .ie n .SS """ev_fork"" \- the audacity to resume the event loop after a fork" |
3220 | .el .SS "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
3508 | .el .SS "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
3221 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
3509 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
3222 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
3510 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
3223 | whoever is a good citizen cared to tell libev about it by calling |
3511 | whoever is a good citizen cared to tell libev about it by calling |
3224 | \&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the |
3512 | \&\f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the event loop blocks next |
3225 | event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, |
3513 | and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, and only in the child |
3226 | and only in the child after the fork. If whoever good citizen calling |
3514 | after the fork. If whoever good citizen calling \f(CW\*(C`ev_default_fork\*(C'\fR cheats |
3227 | \&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork |
3515 | and calls it in the wrong process, the fork handlers will be invoked, too, |
3228 | handlers will be invoked, too, of course. |
3516 | of course. |
3229 | .PP |
3517 | .PP |
3230 | \fIThe special problem of life after fork \- how is it possible?\fR |
3518 | \fIThe special problem of life after fork \- how is it possible?\fR |
3231 | .IX Subsection "The special problem of life after fork - how is it possible?" |
3519 | .IX Subsection "The special problem of life after fork - how is it possible?" |
3232 | .PP |
3520 | .PP |
3233 | Most uses of \f(CW\*(C`fork()\*(C'\fR consist of forking, then some simple calls to set |
3521 | Most uses of \f(CW\*(C`fork ()\*(C'\fR consist of forking, then some simple calls to set |
3234 | up/change the process environment, followed by a call to \f(CW\*(C`exec()\*(C'\fR. This |
3522 | up/change the process environment, followed by a call to \f(CW\*(C`exec()\*(C'\fR. This |
3235 | sequence should be handled by libev without any problems. |
3523 | sequence should be handled by libev without any problems. |
3236 | .PP |
3524 | .PP |
3237 | This changes when the application actually wants to do event handling |
3525 | This changes when the application actually wants to do event handling |
3238 | in the child, or both parent in child, in effect \*(L"continuing\*(R" after the |
3526 | in the child, or both parent in child, in effect \*(L"continuing\*(R" after the |
… | |
… | |
3307 | \& atexit (program_exits); |
3595 | \& atexit (program_exits); |
3308 | .Ve |
3596 | .Ve |
3309 | .ie n .SS """ev_async"" \- how to wake up an event loop" |
3597 | .ie n .SS """ev_async"" \- how to wake up an event loop" |
3310 | .el .SS "\f(CWev_async\fP \- how to wake up an event loop" |
3598 | .el .SS "\f(CWev_async\fP \- how to wake up an event loop" |
3311 | .IX Subsection "ev_async - how to wake up an event loop" |
3599 | .IX Subsection "ev_async - how to wake up an event loop" |
3312 | In general, you cannot use an \f(CW\*(C`ev_run\*(C'\fR from multiple threads or other |
3600 | In general, you cannot use an \f(CW\*(C`ev_loop\*(C'\fR from multiple threads or other |
3313 | asynchronous sources such as signal handlers (as opposed to multiple event |
3601 | asynchronous sources such as signal handlers (as opposed to multiple event |
3314 | loops \- those are of course safe to use in different threads). |
3602 | loops \- those are of course safe to use in different threads). |
3315 | .PP |
3603 | .PP |
3316 | Sometimes, however, you need to wake up an event loop you do not control, |
3604 | Sometimes, however, you need to wake up an event loop you do not control, |
3317 | for example because it belongs to another thread. This is what \f(CW\*(C`ev_async\*(C'\fR |
3605 | for example because it belongs to another thread. This is what \f(CW\*(C`ev_async\*(C'\fR |
… | |
… | |
3319 | it by calling \f(CW\*(C`ev_async_send\*(C'\fR, which is thread\- and signal safe. |
3607 | it by calling \f(CW\*(C`ev_async_send\*(C'\fR, which is thread\- and signal safe. |
3320 | .PP |
3608 | .PP |
3321 | This functionality is very similar to \f(CW\*(C`ev_signal\*(C'\fR watchers, as signals, |
3609 | This functionality is very similar to \f(CW\*(C`ev_signal\*(C'\fR watchers, as signals, |
3322 | too, are asynchronous in nature, and signals, too, will be compressed |
3610 | too, are asynchronous in nature, and signals, too, will be compressed |
3323 | (i.e. the number of callback invocations may be less than the number of |
3611 | (i.e. the number of callback invocations may be less than the number of |
3324 | \&\f(CW\*(C`ev_async_sent\*(C'\fR calls). In fact, you could use signal watchers as a kind |
3612 | \&\f(CW\*(C`ev_async_send\*(C'\fR calls). In fact, you could use signal watchers as a kind |
3325 | of \*(L"global async watchers\*(R" by using a watcher on an otherwise unused |
3613 | of \*(L"global async watchers\*(R" by using a watcher on an otherwise unused |
3326 | signal, and \f(CW\*(C`ev_feed_signal\*(C'\fR to signal this watcher from another thread, |
3614 | signal, and \f(CW\*(C`ev_feed_signal\*(C'\fR to signal this watcher from another thread, |
3327 | even without knowing which loop owns the signal. |
3615 | even without knowing which loop owns the signal. |
3328 | .PP |
|
|
3329 | Unlike \f(CW\*(C`ev_signal\*(C'\fR watchers, \f(CW\*(C`ev_async\*(C'\fR works with any event loop, not |
|
|
3330 | just the default loop. |
|
|
3331 | .PP |
3616 | .PP |
3332 | \fIQueueing\fR |
3617 | \fIQueueing\fR |
3333 | .IX Subsection "Queueing" |
3618 | .IX Subsection "Queueing" |
3334 | .PP |
3619 | .PP |
3335 | \&\f(CW\*(C`ev_async\*(C'\fR does not support queueing of data in any way. The reason |
3620 | \&\f(CW\*(C`ev_async\*(C'\fR does not support queueing of data in any way. The reason |
… | |
… | |
3422 | kind. There is a \f(CW\*(C`ev_async_set\*(C'\fR macro, but using it is utterly pointless, |
3707 | kind. There is a \f(CW\*(C`ev_async_set\*(C'\fR macro, but using it is utterly pointless, |
3423 | trust me. |
3708 | trust me. |
3424 | .IP "ev_async_send (loop, ev_async *)" 4 |
3709 | .IP "ev_async_send (loop, ev_async *)" 4 |
3425 | .IX Item "ev_async_send (loop, ev_async *)" |
3710 | .IX Item "ev_async_send (loop, ev_async *)" |
3426 | Sends/signals/activates the given \f(CW\*(C`ev_async\*(C'\fR watcher, that is, feeds |
3711 | Sends/signals/activates the given \f(CW\*(C`ev_async\*(C'\fR watcher, that is, feeds |
3427 | an \f(CW\*(C`EV_ASYNC\*(C'\fR event on the watcher into the event loop. Unlike |
3712 | an \f(CW\*(C`EV_ASYNC\*(C'\fR event on the watcher into the event loop, and instantly |
|
|
3713 | returns. |
|
|
3714 | .Sp |
3428 | \&\f(CW\*(C`ev_feed_event\*(C'\fR, this call is safe to do from other threads, signal or |
3715 | Unlike \f(CW\*(C`ev_feed_event\*(C'\fR, this call is safe to do from other threads, |
3429 | similar contexts (see the discussion of \f(CW\*(C`EV_ATOMIC_T\*(C'\fR in the embedding |
3716 | signal or similar contexts (see the discussion of \f(CW\*(C`EV_ATOMIC_T\*(C'\fR in the |
3430 | section below on what exactly this means). |
3717 | embedding section below on what exactly this means). |
3431 | .Sp |
3718 | .Sp |
3432 | Note that, as with other watchers in libev, multiple events might get |
3719 | Note that, as with other watchers in libev, multiple events might get |
3433 | compressed into a single callback invocation (another way to look at this |
3720 | compressed into a single callback invocation (another way to look at |
3434 | is that \f(CW\*(C`ev_async\*(C'\fR watchers are level-triggered, set on \f(CW\*(C`ev_async_send\*(C'\fR, |
3721 | this is that \f(CW\*(C`ev_async\*(C'\fR watchers are level-triggered: they are set on |
3435 | reset when the event loop detects that). |
3722 | \&\f(CW\*(C`ev_async_send\*(C'\fR, reset when the event loop detects that). |
3436 | .Sp |
3723 | .Sp |
3437 | This call incurs the overhead of a system call only once per event loop |
3724 | This call incurs the overhead of at most one extra system call per event |
3438 | iteration, so while the overhead might be noticeable, it doesn't apply to |
3725 | loop iteration, if the event loop is blocked, and no syscall at all if |
3439 | repeated calls to \f(CW\*(C`ev_async_send\*(C'\fR for the same event loop. |
3726 | the event loop (or your program) is processing events. That means that |
|
|
3727 | repeated calls are basically free (there is no need to avoid calls for |
|
|
3728 | performance reasons) and that the overhead becomes smaller (typically |
|
|
3729 | zero) under load. |
3440 | .IP "bool = ev_async_pending (ev_async *)" 4 |
3730 | .IP "bool = ev_async_pending (ev_async *)" 4 |
3441 | .IX Item "bool = ev_async_pending (ev_async *)" |
3731 | .IX Item "bool = ev_async_pending (ev_async *)" |
3442 | Returns a non-zero value when \f(CW\*(C`ev_async_send\*(C'\fR has been called on the |
3732 | Returns a non-zero value when \f(CW\*(C`ev_async_send\*(C'\fR has been called on the |
3443 | watcher but the event has not yet been processed (or even noted) by the |
3733 | watcher but the event has not yet been processed (or even noted) by the |
3444 | event loop. |
3734 | event loop. |
… | |
… | |
3453 | is a time window between the event loop checking and resetting the async |
3743 | is a time window between the event loop checking and resetting the async |
3454 | notification, and the callback being invoked. |
3744 | notification, and the callback being invoked. |
3455 | .SH "OTHER FUNCTIONS" |
3745 | .SH "OTHER FUNCTIONS" |
3456 | .IX Header "OTHER FUNCTIONS" |
3746 | .IX Header "OTHER FUNCTIONS" |
3457 | There are some other functions of possible interest. Described. Here. Now. |
3747 | There are some other functions of possible interest. Described. Here. Now. |
3458 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 |
3748 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback, arg)" 4 |
3459 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" |
3749 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback, arg)" |
3460 | This function combines a simple timer and an I/O watcher, calls your |
3750 | This function combines a simple timer and an I/O watcher, calls your |
3461 | callback on whichever event happens first and automatically stops both |
3751 | callback on whichever event happens first and automatically stops both |
3462 | watchers. This is useful if you want to wait for a single event on an fd |
3752 | watchers. This is useful if you want to wait for a single event on an fd |
3463 | or timeout without having to allocate/configure/start/stop/free one or |
3753 | or timeout without having to allocate/configure/start/stop/free one or |
3464 | more watchers yourself. |
3754 | more watchers yourself. |
… | |
… | |
3476 | \&\f(CW\*(C`EV_ERROR\*(C'\fR, \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or \f(CW\*(C`EV_TIMER\*(C'\fR) and the \f(CW\*(C`arg\*(C'\fR |
3766 | \&\f(CW\*(C`EV_ERROR\*(C'\fR, \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or \f(CW\*(C`EV_TIMER\*(C'\fR) and the \f(CW\*(C`arg\*(C'\fR |
3477 | value passed to \f(CW\*(C`ev_once\*(C'\fR. Note that it is possible to receive \fIboth\fR |
3767 | value passed to \f(CW\*(C`ev_once\*(C'\fR. Note that it is possible to receive \fIboth\fR |
3478 | a timeout and an io event at the same time \- you probably should give io |
3768 | a timeout and an io event at the same time \- you probably should give io |
3479 | events precedence. |
3769 | events precedence. |
3480 | .Sp |
3770 | .Sp |
3481 | Example: wait up to ten seconds for data to appear on \s-1STDIN_FILENO\s0. |
3771 | Example: wait up to ten seconds for data to appear on \s-1STDIN_FILENO.\s0 |
3482 | .Sp |
3772 | .Sp |
3483 | .Vb 7 |
3773 | .Vb 7 |
3484 | \& static void stdin_ready (int revents, void *arg) |
3774 | \& static void stdin_ready (int revents, void *arg) |
3485 | \& { |
3775 | \& { |
3486 | \& if (revents & EV_READ) |
3776 | \& if (revents & EV_READ) |
… | |
… | |
3492 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3782 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3493 | .Ve |
3783 | .Ve |
3494 | .IP "ev_feed_fd_event (loop, int fd, int revents)" 4 |
3784 | .IP "ev_feed_fd_event (loop, int fd, int revents)" 4 |
3495 | .IX Item "ev_feed_fd_event (loop, int fd, int revents)" |
3785 | .IX Item "ev_feed_fd_event (loop, int fd, int revents)" |
3496 | Feed an event on the given fd, as if a file descriptor backend detected |
3786 | Feed an event on the given fd, as if a file descriptor backend detected |
3497 | the given events it. |
3787 | the given events. |
3498 | .IP "ev_feed_signal_event (loop, int signum)" 4 |
3788 | .IP "ev_feed_signal_event (loop, int signum)" 4 |
3499 | .IX Item "ev_feed_signal_event (loop, int signum)" |
3789 | .IX Item "ev_feed_signal_event (loop, int signum)" |
3500 | Feed an event as if the given signal occurred. See also \f(CW\*(C`ev_feed_signal\*(C'\fR, |
3790 | Feed an event as if the given signal occurred. See also \f(CW\*(C`ev_feed_signal\*(C'\fR, |
3501 | which is async-safe. |
3791 | which is async-safe. |
3502 | .SH "COMMON OR USEFUL IDIOMS (OR BOTH)" |
3792 | .SH "COMMON OR USEFUL IDIOMS (OR BOTH)" |
3503 | .IX Header "COMMON OR USEFUL IDIOMS (OR BOTH)" |
3793 | .IX Header "COMMON OR USEFUL IDIOMS (OR BOTH)" |
3504 | This section explains some common idioms that are not immediately |
3794 | This section explains some common idioms that are not immediately |
3505 | obvious. Note that examples are sprinkled over the whole manual, and this |
3795 | obvious. Note that examples are sprinkled over the whole manual, and this |
3506 | section only contains stuff that wouldn't fit anywhere else. |
3796 | section only contains stuff that wouldn't fit anywhere else. |
3507 | .SS "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" |
3797 | .SS "\s-1ASSOCIATING CUSTOM DATA WITH A WATCHER\s0" |
3508 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
3798 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
3509 | Each watcher has, by default, a \f(CW\*(C`void *data\*(C'\fR member that you can read |
3799 | Each watcher has, by default, a \f(CW\*(C`void *data\*(C'\fR member that you can read |
3510 | or modify at any time: libev will completely ignore it. This can be used |
3800 | or modify at any time: libev will completely ignore it. This can be used |
3511 | to associate arbitrary data with your watcher. If you need more data and |
3801 | to associate arbitrary data with your watcher. If you need more data and |
3512 | don't want to allocate memory separately and store a pointer to it in that |
3802 | don't want to allocate memory separately and store a pointer to it in that |
… | |
… | |
3538 | \& } |
3828 | \& } |
3539 | .Ve |
3829 | .Ve |
3540 | .PP |
3830 | .PP |
3541 | More interesting and less C\-conformant ways of casting your callback |
3831 | More interesting and less C\-conformant ways of casting your callback |
3542 | function type instead have been omitted. |
3832 | function type instead have been omitted. |
3543 | .SS "\s-1BUILDING\s0 \s-1YOUR\s0 \s-1OWN\s0 \s-1COMPOSITE\s0 \s-1WATCHERS\s0" |
3833 | .SS "\s-1BUILDING YOUR OWN COMPOSITE WATCHERS\s0" |
3544 | .IX Subsection "BUILDING YOUR OWN COMPOSITE WATCHERS" |
3834 | .IX Subsection "BUILDING YOUR OWN COMPOSITE WATCHERS" |
3545 | Another common scenario is to use some data structure with multiple |
3835 | Another common scenario is to use some data structure with multiple |
3546 | embedded watchers, in effect creating your own watcher that combines |
3836 | embedded watchers, in effect creating your own watcher that combines |
3547 | multiple libev event sources into one \*(L"super-watcher\*(R": |
3837 | multiple libev event sources into one \*(L"super-watcher\*(R": |
3548 | .PP |
3838 | .PP |
… | |
… | |
3576 | \& { |
3866 | \& { |
3577 | \& struct my_biggy big = (struct my_biggy *) |
3867 | \& struct my_biggy big = (struct my_biggy *) |
3578 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
3868 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
3579 | \& } |
3869 | \& } |
3580 | .Ve |
3870 | .Ve |
3581 | .SS "\s-1MODEL/NESTED\s0 \s-1EVENT\s0 \s-1LOOP\s0 \s-1INVOCATIONS\s0 \s-1AND\s0 \s-1EXIT\s0 \s-1CONDITIONS\s0" |
3871 | .SS "\s-1AVOIDING FINISHING BEFORE RETURNING\s0" |
|
|
3872 | .IX Subsection "AVOIDING FINISHING BEFORE RETURNING" |
|
|
3873 | Often you have structures like this in event-based programs: |
|
|
3874 | .PP |
|
|
3875 | .Vb 4 |
|
|
3876 | \& callback () |
|
|
3877 | \& { |
|
|
3878 | \& free (request); |
|
|
3879 | \& } |
|
|
3880 | \& |
|
|
3881 | \& request = start_new_request (..., callback); |
|
|
3882 | .Ve |
|
|
3883 | .PP |
|
|
3884 | The intent is to start some \*(L"lengthy\*(R" operation. The \f(CW\*(C`request\*(C'\fR could be |
|
|
3885 | used to cancel the operation, or do other things with it. |
|
|
3886 | .PP |
|
|
3887 | It's not uncommon to have code paths in \f(CW\*(C`start_new_request\*(C'\fR that |
|
|
3888 | immediately invoke the callback, for example, to report errors. Or you add |
|
|
3889 | some caching layer that finds that it can skip the lengthy aspects of the |
|
|
3890 | operation and simply invoke the callback with the result. |
|
|
3891 | .PP |
|
|
3892 | The problem here is that this will happen \fIbefore\fR \f(CW\*(C`start_new_request\*(C'\fR |
|
|
3893 | has returned, so \f(CW\*(C`request\*(C'\fR is not set. |
|
|
3894 | .PP |
|
|
3895 | Even if you pass the request by some safer means to the callback, you |
|
|
3896 | might want to do something to the request after starting it, such as |
|
|
3897 | canceling it, which probably isn't working so well when the callback has |
|
|
3898 | already been invoked. |
|
|
3899 | .PP |
|
|
3900 | A common way around all these issues is to make sure that |
|
|
3901 | \&\f(CW\*(C`start_new_request\*(C'\fR \fIalways\fR returns before the callback is invoked. If |
|
|
3902 | \&\f(CW\*(C`start_new_request\*(C'\fR immediately knows the result, it can artificially |
|
|
3903 | delay invoking the callback by using a \f(CW\*(C`prepare\*(C'\fR or \f(CW\*(C`idle\*(C'\fR watcher for |
|
|
3904 | example, or more sneakily, by reusing an existing (stopped) watcher and |
|
|
3905 | pushing it into the pending queue: |
|
|
3906 | .PP |
|
|
3907 | .Vb 2 |
|
|
3908 | \& ev_set_cb (watcher, callback); |
|
|
3909 | \& ev_feed_event (EV_A_ watcher, 0); |
|
|
3910 | .Ve |
|
|
3911 | .PP |
|
|
3912 | This way, \f(CW\*(C`start_new_request\*(C'\fR can safely return before the callback is |
|
|
3913 | invoked, while not delaying callback invocation too much. |
|
|
3914 | .SS "\s-1MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS\s0" |
3582 | .IX Subsection "MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS" |
3915 | .IX Subsection "MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS" |
3583 | Often (especially in \s-1GUI\s0 toolkits) there are places where you have |
3916 | Often (especially in \s-1GUI\s0 toolkits) there are places where you have |
3584 | \&\fImodal\fR interaction, which is most easily implemented by recursively |
3917 | \&\fImodal\fR interaction, which is most easily implemented by recursively |
3585 | invoking \f(CW\*(C`ev_run\*(C'\fR. |
3918 | invoking \f(CW\*(C`ev_run\*(C'\fR. |
3586 | .PP |
3919 | .PP |
3587 | This brings the problem of exiting \- a callback might want to finish the |
3920 | This brings the problem of exiting \- a callback might want to finish the |
3588 | main \f(CW\*(C`ev_run\*(C'\fR call, but not the nested one (e.g. user clicked \*(L"Quit\*(R", but |
3921 | main \f(CW\*(C`ev_run\*(C'\fR call, but not the nested one (e.g. user clicked \*(L"Quit\*(R", but |
3589 | a modal \*(L"Are you sure?\*(R" dialog is still waiting), or just the nested one |
3922 | a modal \*(L"Are you sure?\*(R" dialog is still waiting), or just the nested one |
3590 | and not the main one (e.g. user clocked \*(L"Ok\*(R" in a modal dialog), or some |
3923 | and not the main one (e.g. user clocked \*(L"Ok\*(R" in a modal dialog), or some |
3591 | other combination: In these cases, \f(CW\*(C`ev_break\*(C'\fR will not work alone. |
3924 | other combination: In these cases, a simple \f(CW\*(C`ev_break\*(C'\fR will not work. |
3592 | .PP |
3925 | .PP |
3593 | The solution is to maintain \*(L"break this loop\*(R" variable for each \f(CW\*(C`ev_run\*(C'\fR |
3926 | The solution is to maintain \*(L"break this loop\*(R" variable for each \f(CW\*(C`ev_run\*(C'\fR |
3594 | invocation, and use a loop around \f(CW\*(C`ev_run\*(C'\fR until the condition is |
3927 | invocation, and use a loop around \f(CW\*(C`ev_run\*(C'\fR until the condition is |
3595 | triggered, using \f(CW\*(C`EVRUN_ONCE\*(C'\fR: |
3928 | triggered, using \f(CW\*(C`EVRUN_ONCE\*(C'\fR: |
3596 | .PP |
3929 | .PP |
… | |
… | |
3599 | \& int exit_main_loop = 0; |
3932 | \& int exit_main_loop = 0; |
3600 | \& |
3933 | \& |
3601 | \& while (!exit_main_loop) |
3934 | \& while (!exit_main_loop) |
3602 | \& ev_run (EV_DEFAULT_ EVRUN_ONCE); |
3935 | \& ev_run (EV_DEFAULT_ EVRUN_ONCE); |
3603 | \& |
3936 | \& |
3604 | \& // in a model watcher |
3937 | \& // in a modal watcher |
3605 | \& int exit_nested_loop = 0; |
3938 | \& int exit_nested_loop = 0; |
3606 | \& |
3939 | \& |
3607 | \& while (!exit_nested_loop) |
3940 | \& while (!exit_nested_loop) |
3608 | \& ev_run (EV_A_ EVRUN_ONCE); |
3941 | \& ev_run (EV_A_ EVRUN_ONCE); |
3609 | .Ve |
3942 | .Ve |
… | |
… | |
3618 | \& exit_main_loop = 1; |
3951 | \& exit_main_loop = 1; |
3619 | \& |
3952 | \& |
3620 | \& // exit both |
3953 | \& // exit both |
3621 | \& exit_main_loop = exit_nested_loop = 1; |
3954 | \& exit_main_loop = exit_nested_loop = 1; |
3622 | .Ve |
3955 | .Ve |
3623 | .SS "\s-1THREAD\s0 \s-1LOCKING\s0 \s-1EXAMPLE\s0" |
3956 | .SS "\s-1THREAD LOCKING EXAMPLE\s0" |
3624 | .IX Subsection "THREAD LOCKING EXAMPLE" |
3957 | .IX Subsection "THREAD LOCKING EXAMPLE" |
3625 | Here is a fictitious example of how to run an event loop in a different |
3958 | Here is a fictitious example of how to run an event loop in a different |
3626 | thread from where callbacks are being invoked and watchers are |
3959 | thread from where callbacks are being invoked and watchers are |
3627 | created/added/removed. |
3960 | created/added/removed. |
3628 | .PP |
3961 | .PP |
… | |
… | |
3658 | \& // now associate this with the loop |
3991 | \& // now associate this with the loop |
3659 | \& ev_set_userdata (EV_A_ u); |
3992 | \& ev_set_userdata (EV_A_ u); |
3660 | \& ev_set_invoke_pending_cb (EV_A_ l_invoke); |
3993 | \& ev_set_invoke_pending_cb (EV_A_ l_invoke); |
3661 | \& ev_set_loop_release_cb (EV_A_ l_release, l_acquire); |
3994 | \& ev_set_loop_release_cb (EV_A_ l_release, l_acquire); |
3662 | \& |
3995 | \& |
3663 | \& // then create the thread running ev_loop |
3996 | \& // then create the thread running ev_run |
3664 | \& pthread_create (&u\->tid, 0, l_run, EV_A); |
3997 | \& pthread_create (&u\->tid, 0, l_run, EV_A); |
3665 | \& } |
3998 | \& } |
3666 | .Ve |
3999 | .Ve |
3667 | .PP |
4000 | .PP |
3668 | The callback for the \f(CW\*(C`ev_async\*(C'\fR watcher does nothing: the watcher is used |
4001 | The callback for the \f(CW\*(C`ev_async\*(C'\fR watcher does nothing: the watcher is used |
… | |
… | |
3769 | .PP |
4102 | .PP |
3770 | Note that sending the \f(CW\*(C`ev_async\*(C'\fR watcher is required because otherwise |
4103 | Note that sending the \f(CW\*(C`ev_async\*(C'\fR watcher is required because otherwise |
3771 | an event loop currently blocking in the kernel will have no knowledge |
4104 | an event loop currently blocking in the kernel will have no knowledge |
3772 | about the newly added timer. By waking up the loop it will pick up any new |
4105 | about the newly added timer. By waking up the loop it will pick up any new |
3773 | watchers in the next event loop iteration. |
4106 | watchers in the next event loop iteration. |
3774 | .SS "\s-1THREADS\s0, \s-1COROUTINES\s0, \s-1CONTINUATIONS\s0, \s-1QUEUES\s0... \s-1INSTEAD\s0 \s-1OF\s0 \s-1CALLBACKS\s0" |
4107 | .SS "\s-1THREADS, COROUTINES, CONTINUATIONS, QUEUES... INSTEAD OF CALLBACKS\s0" |
3775 | .IX Subsection "THREADS, COROUTINES, CONTINUATIONS, QUEUES... INSTEAD OF CALLBACKS" |
4108 | .IX Subsection "THREADS, COROUTINES, CONTINUATIONS, QUEUES... INSTEAD OF CALLBACKS" |
3776 | While the overhead of a callback that e.g. schedules a thread is small, it |
4109 | While the overhead of a callback that e.g. schedules a thread is small, it |
3777 | is still an overhead. If you embed libev, and your main usage is with some |
4110 | is still an overhead. If you embed libev, and your main usage is with some |
3778 | kind of threads or coroutines, you might want to customise libev so that |
4111 | kind of threads or coroutines, you might want to customise libev so that |
3779 | doesn't need callbacks anymore. |
4112 | doesn't need callbacks anymore. |
… | |
… | |
3801 | .PP |
4134 | .PP |
3802 | .Vb 6 |
4135 | .Vb 6 |
3803 | \& void |
4136 | \& void |
3804 | \& wait_for_event (ev_watcher *w) |
4137 | \& wait_for_event (ev_watcher *w) |
3805 | \& { |
4138 | \& { |
3806 | \& ev_cb_set (w) = current_coro; |
4139 | \& ev_set_cb (w, current_coro); |
3807 | \& switch_to (libev_coro); |
4140 | \& switch_to (libev_coro); |
3808 | \& } |
4141 | \& } |
3809 | .Ve |
4142 | .Ve |
3810 | .PP |
4143 | .PP |
3811 | That basically suspends the coroutine inside \f(CW\*(C`wait_for_event\*(C'\fR and |
4144 | That basically suspends the coroutine inside \f(CW\*(C`wait_for_event\*(C'\fR and |
3812 | continues the libev coroutine, which, when appropriate, switches back to |
4145 | continues the libev coroutine, which, when appropriate, switches back to |
3813 | this or any other coroutine. I am sure if you sue this your own :) |
4146 | this or any other coroutine. |
3814 | .PP |
4147 | .PP |
3815 | You can do similar tricks if you have, say, threads with an event queue \- |
4148 | You can do similar tricks if you have, say, threads with an event queue \- |
3816 | instead of storing a coroutine, you store the queue object and instead of |
4149 | instead of storing a coroutine, you store the queue object and instead of |
3817 | switching to a coroutine, you push the watcher onto the queue and notify |
4150 | switching to a coroutine, you push the watcher onto the queue and notify |
3818 | any waiters. |
4151 | any waiters. |
3819 | .PP |
4152 | .PP |
3820 | To embed libev, see \s-1EMBEDDING\s0, but in short, it's easiest to create two |
4153 | To embed libev, see \*(L"\s-1EMBEDDING\*(R"\s0, but in short, it's easiest to create two |
3821 | files, \fImy_ev.h\fR and \fImy_ev.c\fR that include the respective libev files: |
4154 | files, \fImy_ev.h\fR and \fImy_ev.c\fR that include the respective libev files: |
3822 | .PP |
4155 | .PP |
3823 | .Vb 4 |
4156 | .Vb 4 |
3824 | \& // my_ev.h |
4157 | \& // my_ev.h |
3825 | \& #define EV_CB_DECLARE(type) struct my_coro *cb; |
4158 | \& #define EV_CB_DECLARE(type) struct my_coro *cb; |
3826 | \& #define EV_CB_INVOKE(watcher) switch_to ((watcher)\->cb); |
4159 | \& #define EV_CB_INVOKE(watcher) switch_to ((watcher)\->cb) |
3827 | \& #include "../libev/ev.h" |
4160 | \& #include "../libev/ev.h" |
3828 | \& |
4161 | \& |
3829 | \& // my_ev.c |
4162 | \& // my_ev.c |
3830 | \& #define EV_H "my_ev.h" |
4163 | \& #define EV_H "my_ev.h" |
3831 | \& #include "../libev/ev.c" |
4164 | \& #include "../libev/ev.c" |
… | |
… | |
3864 | .IP "\(bu" 4 |
4197 | .IP "\(bu" 4 |
3865 | The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need |
4198 | The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need |
3866 | to use the libev header file and library. |
4199 | to use the libev header file and library. |
3867 | .SH "\*(C+ SUPPORT" |
4200 | .SH "\*(C+ SUPPORT" |
3868 | .IX Header " SUPPORT" |
4201 | .IX Header " SUPPORT" |
|
|
4202 | .SS "C \s-1API\s0" |
|
|
4203 | .IX Subsection "C API" |
|
|
4204 | The normal C \s-1API\s0 should work fine when used from \*(C+: both ev.h and the |
|
|
4205 | libev sources can be compiled as \*(C+. Therefore, code that uses the C \s-1API\s0 |
|
|
4206 | will work fine. |
|
|
4207 | .PP |
|
|
4208 | Proper exception specifications might have to be added to callbacks passed |
|
|
4209 | to libev: exceptions may be thrown only from watcher callbacks, all other |
|
|
4210 | callbacks (allocator, syserr, loop acquire/release and periodic reschedule |
|
|
4211 | callbacks) must not throw exceptions, and might need a \f(CW\*(C`noexcept\*(C'\fR |
|
|
4212 | specification. If you have code that needs to be compiled as both C and |
|
|
4213 | \&\*(C+ you can use the \f(CW\*(C`EV_NOEXCEPT\*(C'\fR macro for this: |
|
|
4214 | .PP |
|
|
4215 | .Vb 6 |
|
|
4216 | \& static void |
|
|
4217 | \& fatal_error (const char *msg) EV_NOEXCEPT |
|
|
4218 | \& { |
|
|
4219 | \& perror (msg); |
|
|
4220 | \& abort (); |
|
|
4221 | \& } |
|
|
4222 | \& |
|
|
4223 | \& ... |
|
|
4224 | \& ev_set_syserr_cb (fatal_error); |
|
|
4225 | .Ve |
|
|
4226 | .PP |
|
|
4227 | The only \s-1API\s0 functions that can currently throw exceptions are \f(CW\*(C`ev_run\*(C'\fR, |
|
|
4228 | \&\f(CW\*(C`ev_invoke\*(C'\fR, \f(CW\*(C`ev_invoke_pending\*(C'\fR and \f(CW\*(C`ev_loop_destroy\*(C'\fR (the latter |
|
|
4229 | because it runs cleanup watchers). |
|
|
4230 | .PP |
|
|
4231 | Throwing exceptions in watcher callbacks is only supported if libev itself |
|
|
4232 | is compiled with a \*(C+ compiler or your C and \*(C+ environments allow |
|
|
4233 | throwing exceptions through C libraries (most do). |
|
|
4234 | .SS "\*(C+ \s-1API\s0" |
|
|
4235 | .IX Subsection " API" |
3869 | Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow |
4236 | Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow |
3870 | you to use some convenience methods to start/stop watchers and also change |
4237 | you to use some convenience methods to start/stop watchers and also change |
3871 | the callback model to a model using method callbacks on objects. |
4238 | the callback model to a model using method callbacks on objects. |
3872 | .PP |
4239 | .PP |
3873 | To use it, |
4240 | To use it, |
… | |
… | |
3889 | Currently, functions, static and non-static member functions and classes |
4256 | Currently, functions, static and non-static member functions and classes |
3890 | with \f(CW\*(C`operator ()\*(C'\fR can be used as callbacks. Other types should be easy |
4257 | with \f(CW\*(C`operator ()\*(C'\fR can be used as callbacks. Other types should be easy |
3891 | to add as long as they only need one additional pointer for context. If |
4258 | to add as long as they only need one additional pointer for context. If |
3892 | you need support for other types of functors please contact the author |
4259 | you need support for other types of functors please contact the author |
3893 | (preferably after implementing it). |
4260 | (preferably after implementing it). |
|
|
4261 | .PP |
|
|
4262 | For all this to work, your \*(C+ compiler either has to use the same calling |
|
|
4263 | conventions as your C compiler (for static member functions), or you have |
|
|
4264 | to embed libev and compile libev itself as \*(C+. |
3894 | .PP |
4265 | .PP |
3895 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
4266 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
3896 | .ie n .IP """ev::READ"", ""ev::WRITE"" etc." 4 |
4267 | .ie n .IP """ev::READ"", ""ev::WRITE"" etc." 4 |
3897 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
4268 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
3898 | .IX Item "ev::READ, ev::WRITE etc." |
4269 | .IX Item "ev::READ, ev::WRITE etc." |
… | |
… | |
3906 | .el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4 |
4277 | .el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4 |
3907 | .IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc." |
4278 | .IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc." |
3908 | For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of |
4279 | For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of |
3909 | the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR |
4280 | the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR |
3910 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
4281 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
3911 | defines by many implementations. |
4282 | defined by many implementations. |
3912 | .Sp |
4283 | .Sp |
3913 | All of those classes have these methods: |
4284 | All of those classes have these methods: |
3914 | .RS 4 |
4285 | .RS 4 |
3915 | .IP "ev::TYPE::TYPE ()" 4 |
4286 | .IP "ev::TYPE::TYPE ()" 4 |
3916 | .IX Item "ev::TYPE::TYPE ()" |
4287 | .IX Item "ev::TYPE::TYPE ()" |
… | |
… | |
3979 | \& void operator() (ev::io &w, int revents) |
4350 | \& void operator() (ev::io &w, int revents) |
3980 | \& { |
4351 | \& { |
3981 | \& ... |
4352 | \& ... |
3982 | \& } |
4353 | \& } |
3983 | \& } |
4354 | \& } |
3984 | \& |
4355 | \& |
3985 | \& myfunctor f; |
4356 | \& myfunctor f; |
3986 | \& |
4357 | \& |
3987 | \& ev::io w; |
4358 | \& ev::io w; |
3988 | \& w.set (&f); |
4359 | \& w.set (&f); |
3989 | .Ve |
4360 | .Ve |
… | |
… | |
4007 | .IX Item "w->set (loop)" |
4378 | .IX Item "w->set (loop)" |
4008 | Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only |
4379 | Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only |
4009 | do this when the watcher is inactive (and not pending either). |
4380 | do this when the watcher is inactive (and not pending either). |
4010 | .IP "w\->set ([arguments])" 4 |
4381 | .IP "w\->set ([arguments])" 4 |
4011 | .IX Item "w->set ([arguments])" |
4382 | .IX Item "w->set ([arguments])" |
4012 | Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same arguments. Either this |
4383 | Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR (except for \f(CW\*(C`ev::embed\*(C'\fR watchers>), |
4013 | method or a suitable start method must be called at least once. Unlike the |
4384 | with the same arguments. Either this method or a suitable start method |
4014 | C counterpart, an active watcher gets automatically stopped and restarted |
4385 | must be called at least once. Unlike the C counterpart, an active watcher |
4015 | when reconfiguring it with this method. |
4386 | gets automatically stopped and restarted when reconfiguring it with this |
|
|
4387 | method. |
|
|
4388 | .Sp |
|
|
4389 | For \f(CW\*(C`ev::embed\*(C'\fR watchers this method is called \f(CW\*(C`set_embed\*(C'\fR, to avoid |
|
|
4390 | clashing with the \f(CW\*(C`set (loop)\*(C'\fR method. |
4016 | .IP "w\->start ()" 4 |
4391 | .IP "w\->start ()" 4 |
4017 | .IX Item "w->start ()" |
4392 | .IX Item "w->start ()" |
4018 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the |
4393 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the |
4019 | constructor already stores the event loop. |
4394 | constructor already stores the event loop. |
4020 | .IP "w\->start ([arguments])" 4 |
4395 | .IP "w\->start ([arguments])" 4 |
… | |
… | |
4047 | .PP |
4422 | .PP |
4048 | .Vb 5 |
4423 | .Vb 5 |
4049 | \& class myclass |
4424 | \& class myclass |
4050 | \& { |
4425 | \& { |
4051 | \& ev::io io ; void io_cb (ev::io &w, int revents); |
4426 | \& ev::io io ; void io_cb (ev::io &w, int revents); |
4052 | \& ev::io2 io2 ; void io2_cb (ev::io &w, int revents); |
4427 | \& ev::io io2 ; void io2_cb (ev::io &w, int revents); |
4053 | \& ev::idle idle; void idle_cb (ev::idle &w, int revents); |
4428 | \& ev::idle idle; void idle_cb (ev::idle &w, int revents); |
4054 | \& |
4429 | \& |
4055 | \& myclass (int fd) |
4430 | \& myclass (int fd) |
4056 | \& { |
4431 | \& { |
4057 | \& io .set <myclass, &myclass::io_cb > (this); |
4432 | \& io .set <myclass, &myclass::io_cb > (this); |
… | |
… | |
4078 | there are additional modules that implement libev-compatible interfaces |
4453 | there are additional modules that implement libev-compatible interfaces |
4079 | to \f(CW\*(C`libadns\*(C'\fR (\f(CW\*(C`EV::ADNS\*(C'\fR, but \f(CW\*(C`AnyEvent::DNS\*(C'\fR is preferred nowadays), |
4454 | to \f(CW\*(C`libadns\*(C'\fR (\f(CW\*(C`EV::ADNS\*(C'\fR, but \f(CW\*(C`AnyEvent::DNS\*(C'\fR is preferred nowadays), |
4080 | \&\f(CW\*(C`Net::SNMP\*(C'\fR (\f(CW\*(C`Net::SNMP::EV\*(C'\fR) and the \f(CW\*(C`libglib\*(C'\fR event core (\f(CW\*(C`Glib::EV\*(C'\fR |
4455 | \&\f(CW\*(C`Net::SNMP\*(C'\fR (\f(CW\*(C`Net::SNMP::EV\*(C'\fR) and the \f(CW\*(C`libglib\*(C'\fR event core (\f(CW\*(C`Glib::EV\*(C'\fR |
4081 | and \f(CW\*(C`EV::Glib\*(C'\fR). |
4456 | and \f(CW\*(C`EV::Glib\*(C'\fR). |
4082 | .Sp |
4457 | .Sp |
4083 | It can be found and installed via \s-1CPAN\s0, its homepage is at |
4458 | It can be found and installed via \s-1CPAN,\s0 its homepage is at |
4084 | <http://software.schmorp.de/pkg/EV>. |
4459 | <http://software.schmorp.de/pkg/EV>. |
4085 | .IP "Python" 4 |
4460 | .IP "Python" 4 |
4086 | .IX Item "Python" |
4461 | .IX Item "Python" |
4087 | Python bindings can be found at <http://code.google.com/p/pyev/>. It |
4462 | Python bindings can be found at <http://code.google.com/p/pyev/>. It |
4088 | seems to be quite complete and well-documented. |
4463 | seems to be quite complete and well-documented. |
… | |
… | |
4100 | A haskell binding to libev is available at |
4475 | A haskell binding to libev is available at |
4101 | <http://hackage.haskell.org/cgi\-bin/hackage\-scripts/package/hlibev>. |
4476 | <http://hackage.haskell.org/cgi\-bin/hackage\-scripts/package/hlibev>. |
4102 | .IP "D" 4 |
4477 | .IP "D" 4 |
4103 | .IX Item "D" |
4478 | .IX Item "D" |
4104 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
4479 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
4105 | be found at <http://proj.llucax.com.ar/wiki/evd>. |
4480 | be found at <http://www.llucax.com.ar/proj/ev.d/index.html>. |
4106 | .IP "Ocaml" 4 |
4481 | .IP "Ocaml" 4 |
4107 | .IX Item "Ocaml" |
4482 | .IX Item "Ocaml" |
4108 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
4483 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
4109 | <http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/>. |
4484 | <http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/>. |
4110 | .IP "Lua" 4 |
4485 | .IP "Lua" 4 |
4111 | .IX Item "Lua" |
4486 | .IX Item "Lua" |
4112 | Brian Maher has written a partial interface to libev for lua (at the |
4487 | Brian Maher has written a partial interface to libev for lua (at the |
4113 | time of this writing, only \f(CW\*(C`ev_io\*(C'\fR and \f(CW\*(C`ev_timer\*(C'\fR), to be found at |
4488 | time of this writing, only \f(CW\*(C`ev_io\*(C'\fR and \f(CW\*(C`ev_timer\*(C'\fR), to be found at |
4114 | <http://github.com/brimworks/lua\-ev>. |
4489 | <http://github.com/brimworks/lua\-ev>. |
|
|
4490 | .IP "Javascript" 4 |
|
|
4491 | .IX Item "Javascript" |
|
|
4492 | Node.js (<http://nodejs.org>) uses libev as the underlying event library. |
|
|
4493 | .IP "Others" 4 |
|
|
4494 | .IX Item "Others" |
|
|
4495 | There are others, and I stopped counting. |
4115 | .SH "MACRO MAGIC" |
4496 | .SH "MACRO MAGIC" |
4116 | .IX Header "MACRO MAGIC" |
4497 | .IX Header "MACRO MAGIC" |
4117 | Libev can be compiled with a variety of options, the most fundamental |
4498 | Libev can be compiled with a variety of options, the most fundamental |
4118 | of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) |
4499 | of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) |
4119 | functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
4500 | functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
… | |
… | |
4154 | suitable for use with \f(CW\*(C`EV_A\*(C'\fR. |
4535 | suitable for use with \f(CW\*(C`EV_A\*(C'\fR. |
4155 | .ie n .IP """EV_DEFAULT"", ""EV_DEFAULT_""" 4 |
4536 | .ie n .IP """EV_DEFAULT"", ""EV_DEFAULT_""" 4 |
4156 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
4537 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
4157 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
4538 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
4158 | Similar to the other two macros, this gives you the value of the default |
4539 | Similar to the other two macros, this gives you the value of the default |
4159 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). |
4540 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). The default loop |
|
|
4541 | will be initialised if it isn't already initialised. |
|
|
4542 | .Sp |
|
|
4543 | For non-multiplicity builds, these macros do nothing, so you always have |
|
|
4544 | to initialise the loop somewhere. |
4160 | .ie n .IP """EV_DEFAULT_UC"", ""EV_DEFAULT_UC_""" 4 |
4545 | .ie n .IP """EV_DEFAULT_UC"", ""EV_DEFAULT_UC_""" 4 |
4161 | .el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4 |
4546 | .el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4 |
4162 | .IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_" |
4547 | .IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_" |
4163 | Usage identical to \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR, but requires that the |
4548 | Usage identical to \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR, but requires that the |
4164 | default loop has been initialised (\f(CW\*(C`UC\*(C'\fR == unchecked). Their behaviour |
4549 | default loop has been initialised (\f(CW\*(C`UC\*(C'\fR == unchecked). Their behaviour |
… | |
… | |
4198 | .SS "\s-1FILESETS\s0" |
4583 | .SS "\s-1FILESETS\s0" |
4199 | .IX Subsection "FILESETS" |
4584 | .IX Subsection "FILESETS" |
4200 | Depending on what features you need you need to include one or more sets of files |
4585 | Depending on what features you need you need to include one or more sets of files |
4201 | in your application. |
4586 | in your application. |
4202 | .PP |
4587 | .PP |
4203 | \fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR |
4588 | \fI\s-1CORE EVENT LOOP\s0\fR |
4204 | .IX Subsection "CORE EVENT LOOP" |
4589 | .IX Subsection "CORE EVENT LOOP" |
4205 | .PP |
4590 | .PP |
4206 | To include only the libev core (all the \f(CW\*(C`ev_*\*(C'\fR functions), with manual |
4591 | To include only the libev core (all the \f(CW\*(C`ev_*\*(C'\fR functions), with manual |
4207 | configuration (no autoconf): |
4592 | configuration (no autoconf): |
4208 | .PP |
4593 | .PP |
… | |
… | |
4235 | \& ev_vars.h |
4620 | \& ev_vars.h |
4236 | \& ev_wrap.h |
4621 | \& ev_wrap.h |
4237 | \& |
4622 | \& |
4238 | \& ev_win32.c required on win32 platforms only |
4623 | \& ev_win32.c required on win32 platforms only |
4239 | \& |
4624 | \& |
4240 | \& ev_select.c only when select backend is enabled (which is enabled by default) |
4625 | \& ev_select.c only when select backend is enabled |
4241 | \& ev_poll.c only when poll backend is enabled (disabled by default) |
4626 | \& ev_poll.c only when poll backend is enabled |
4242 | \& ev_epoll.c only when the epoll backend is enabled (disabled by default) |
4627 | \& ev_epoll.c only when the epoll backend is enabled |
|
|
4628 | \& ev_linuxaio.c only when the linux aio backend is enabled |
4243 | \& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
4629 | \& ev_kqueue.c only when the kqueue backend is enabled |
4244 | \& ev_port.c only when the solaris port backend is enabled (disabled by default) |
4630 | \& ev_port.c only when the solaris port backend is enabled |
4245 | .Ve |
4631 | .Ve |
4246 | .PP |
4632 | .PP |
4247 | \&\fIev.c\fR includes the backend files directly when enabled, so you only need |
4633 | \&\fIev.c\fR includes the backend files directly when enabled, so you only need |
4248 | to compile this single file. |
4634 | to compile this single file. |
4249 | .PP |
4635 | .PP |
4250 | \fI\s-1LIBEVENT\s0 \s-1COMPATIBILITY\s0 \s-1API\s0\fR |
4636 | \fI\s-1LIBEVENT COMPATIBILITY API\s0\fR |
4251 | .IX Subsection "LIBEVENT COMPATIBILITY API" |
4637 | .IX Subsection "LIBEVENT COMPATIBILITY API" |
4252 | .PP |
4638 | .PP |
4253 | To include the libevent compatibility \s-1API\s0, also include: |
4639 | To include the libevent compatibility \s-1API,\s0 also include: |
4254 | .PP |
4640 | .PP |
4255 | .Vb 1 |
4641 | .Vb 1 |
4256 | \& #include "event.c" |
4642 | \& #include "event.c" |
4257 | .Ve |
4643 | .Ve |
4258 | .PP |
4644 | .PP |
… | |
… | |
4260 | .PP |
4646 | .PP |
4261 | .Vb 1 |
4647 | .Vb 1 |
4262 | \& #include "event.h" |
4648 | \& #include "event.h" |
4263 | .Ve |
4649 | .Ve |
4264 | .PP |
4650 | .PP |
4265 | in the files that want to use the libevent \s-1API\s0. This also includes \fIev.h\fR. |
4651 | in the files that want to use the libevent \s-1API.\s0 This also includes \fIev.h\fR. |
4266 | .PP |
4652 | .PP |
4267 | You need the following additional files for this: |
4653 | You need the following additional files for this: |
4268 | .PP |
4654 | .PP |
4269 | .Vb 2 |
4655 | .Vb 2 |
4270 | \& event.h |
4656 | \& event.h |
4271 | \& event.c |
4657 | \& event.c |
4272 | .Ve |
4658 | .Ve |
4273 | .PP |
4659 | .PP |
4274 | \fI\s-1AUTOCONF\s0 \s-1SUPPORT\s0\fR |
4660 | \fI\s-1AUTOCONF SUPPORT\s0\fR |
4275 | .IX Subsection "AUTOCONF SUPPORT" |
4661 | .IX Subsection "AUTOCONF SUPPORT" |
4276 | .PP |
4662 | .PP |
4277 | Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your configuration in |
4663 | Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your configuration in |
4278 | whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your |
4664 | whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your |
4279 | \&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then |
4665 | \&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then |
… | |
… | |
4282 | For this of course you need the m4 file: |
4668 | For this of course you need the m4 file: |
4283 | .PP |
4669 | .PP |
4284 | .Vb 1 |
4670 | .Vb 1 |
4285 | \& libev.m4 |
4671 | \& libev.m4 |
4286 | .Ve |
4672 | .Ve |
4287 | .SS "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" |
4673 | .SS "\s-1PREPROCESSOR SYMBOLS/MACROS\s0" |
4288 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
4674 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
4289 | Libev can be configured via a variety of preprocessor symbols you have to |
4675 | Libev can be configured via a variety of preprocessor symbols you have to |
4290 | define before including (or compiling) any of its files. The default in |
4676 | define before including (or compiling) any of its files. The default in |
4291 | the absence of autoconf is documented for every option. |
4677 | the absence of autoconf is documented for every option. |
4292 | .PP |
4678 | .PP |
4293 | Symbols marked with \*(L"(h)\*(R" do not change the \s-1ABI\s0, and can have different |
4679 | Symbols marked with \*(L"(h)\*(R" do not change the \s-1ABI,\s0 and can have different |
4294 | values when compiling libev vs. including \fIev.h\fR, so it is permissible |
4680 | values when compiling libev vs. including \fIev.h\fR, so it is permissible |
4295 | to redefine them before including \fIev.h\fR without breaking compatibility |
4681 | to redefine them before including \fIev.h\fR without breaking compatibility |
4296 | to a compiled library. All other symbols change the \s-1ABI\s0, which means all |
4682 | to a compiled library. All other symbols change the \s-1ABI,\s0 which means all |
4297 | users of libev and the libev code itself must be compiled with compatible |
4683 | users of libev and the libev code itself must be compiled with compatible |
4298 | settings. |
4684 | settings. |
4299 | .IP "\s-1EV_COMPAT3\s0 (h)" 4 |
4685 | .IP "\s-1EV_COMPAT3\s0 (h)" 4 |
4300 | .IX Item "EV_COMPAT3 (h)" |
4686 | .IX Item "EV_COMPAT3 (h)" |
4301 | Backwards compatibility is a major concern for libev. This is why this |
4687 | Backwards compatibility is a major concern for libev. This is why this |
… | |
… | |
4319 | supported). It will also not define any of the structs usually found in |
4705 | supported). It will also not define any of the structs usually found in |
4320 | \&\fIevent.h\fR that are not directly supported by the libev core alone. |
4706 | \&\fIevent.h\fR that are not directly supported by the libev core alone. |
4321 | .Sp |
4707 | .Sp |
4322 | In standalone mode, libev will still try to automatically deduce the |
4708 | In standalone mode, libev will still try to automatically deduce the |
4323 | configuration, but has to be more conservative. |
4709 | configuration, but has to be more conservative. |
|
|
4710 | .IP "\s-1EV_USE_FLOOR\s0" 4 |
|
|
4711 | .IX Item "EV_USE_FLOOR" |
|
|
4712 | If defined to be \f(CW1\fR, libev will use the \f(CW\*(C`floor ()\*(C'\fR function for its |
|
|
4713 | periodic reschedule calculations, otherwise libev will fall back on a |
|
|
4714 | portable (slower) implementation. If you enable this, you usually have to |
|
|
4715 | link against libm or something equivalent. Enabling this when the \f(CW\*(C`floor\*(C'\fR |
|
|
4716 | function is not available will fail, so the safe default is to not enable |
|
|
4717 | this. |
4324 | .IP "\s-1EV_USE_MONOTONIC\s0" 4 |
4718 | .IP "\s-1EV_USE_MONOTONIC\s0" 4 |
4325 | .IX Item "EV_USE_MONOTONIC" |
4719 | .IX Item "EV_USE_MONOTONIC" |
4326 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
4720 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
4327 | monotonic clock option at both compile time and runtime. Otherwise no |
4721 | monotonic clock option at both compile time and runtime. Otherwise no |
4328 | use of the monotonic clock option will be attempted. If you enable this, |
4722 | use of the monotonic clock option will be attempted. If you enable this, |
… | |
… | |
4402 | .IX Item "EV_WIN32_CLOSE_FD(fd)" |
4796 | .IX Item "EV_WIN32_CLOSE_FD(fd)" |
4403 | If programs implement their own fd to handle mapping on win32, then this |
4797 | If programs implement their own fd to handle mapping on win32, then this |
4404 | macro can be used to override the \f(CW\*(C`close\*(C'\fR function, useful to unregister |
4798 | macro can be used to override the \f(CW\*(C`close\*(C'\fR function, useful to unregister |
4405 | file descriptors again. Note that the replacement function has to close |
4799 | file descriptors again. Note that the replacement function has to close |
4406 | the underlying \s-1OS\s0 handle. |
4800 | the underlying \s-1OS\s0 handle. |
|
|
4801 | .IP "\s-1EV_USE_WSASOCKET\s0" 4 |
|
|
4802 | .IX Item "EV_USE_WSASOCKET" |
|
|
4803 | If defined to be \f(CW1\fR, libev will use \f(CW\*(C`WSASocket\*(C'\fR to create its internal |
|
|
4804 | communication socket, which works better in some environments. Otherwise, |
|
|
4805 | the normal \f(CW\*(C`socket\*(C'\fR function will be used, which works better in other |
|
|
4806 | environments. |
4407 | .IP "\s-1EV_USE_POLL\s0" 4 |
4807 | .IP "\s-1EV_USE_POLL\s0" 4 |
4408 | .IX Item "EV_USE_POLL" |
4808 | .IX Item "EV_USE_POLL" |
4409 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
4809 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
4410 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
4810 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
4411 | takes precedence over select. |
4811 | takes precedence over select. |
… | |
… | |
4414 | If defined to be \f(CW1\fR, libev will compile in support for the Linux |
4814 | If defined to be \f(CW1\fR, libev will compile in support for the Linux |
4415 | \&\f(CW\*(C`epoll\*(C'\fR(7) backend. Its availability will be detected at runtime, |
4815 | \&\f(CW\*(C`epoll\*(C'\fR(7) backend. Its availability will be detected at runtime, |
4416 | otherwise another method will be used as fallback. This is the preferred |
4816 | otherwise another method will be used as fallback. This is the preferred |
4417 | backend for GNU/Linux systems. If undefined, it will be enabled if the |
4817 | backend for GNU/Linux systems. If undefined, it will be enabled if the |
4418 | headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
4818 | headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
|
|
4819 | .IP "\s-1EV_USE_LINUXAIO\s0" 4 |
|
|
4820 | .IX Item "EV_USE_LINUXAIO" |
|
|
4821 | If defined to be \f(CW1\fR, libev will compile in support for the Linux |
|
|
4822 | aio backend. Due to it's currenbt limitations it has to be requested |
|
|
4823 | explicitly. If undefined, it will be enabled on linux, otherwise |
|
|
4824 | disabled. |
4419 | .IP "\s-1EV_USE_KQUEUE\s0" 4 |
4825 | .IP "\s-1EV_USE_KQUEUE\s0" 4 |
4420 | .IX Item "EV_USE_KQUEUE" |
4826 | .IX Item "EV_USE_KQUEUE" |
4421 | If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style |
4827 | If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style |
4422 | \&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime, |
4828 | \&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime, |
4423 | otherwise another method will be used as fallback. This is the preferred |
4829 | otherwise another method will be used as fallback. This is the preferred |
… | |
… | |
4440 | .IX Item "EV_USE_INOTIFY" |
4846 | .IX Item "EV_USE_INOTIFY" |
4441 | If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify |
4847 | If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify |
4442 | interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will |
4848 | interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will |
4443 | be detected at runtime. If undefined, it will be enabled if the headers |
4849 | be detected at runtime. If undefined, it will be enabled if the headers |
4444 | indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
4850 | indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
|
|
4851 | .IP "\s-1EV_NO_SMP\s0" 4 |
|
|
4852 | .IX Item "EV_NO_SMP" |
|
|
4853 | If defined to be \f(CW1\fR, libev will assume that memory is always coherent |
|
|
4854 | between threads, that is, threads can be used, but threads never run on |
|
|
4855 | different cpus (or different cpu cores). This reduces dependencies |
|
|
4856 | and makes libev faster. |
|
|
4857 | .IP "\s-1EV_NO_THREADS\s0" 4 |
|
|
4858 | .IX Item "EV_NO_THREADS" |
|
|
4859 | If defined to be \f(CW1\fR, libev will assume that it will never be called from |
|
|
4860 | different threads (that includes signal handlers), which is a stronger |
|
|
4861 | assumption than \f(CW\*(C`EV_NO_SMP\*(C'\fR, above. This reduces dependencies and makes |
|
|
4862 | libev faster. |
4445 | .IP "\s-1EV_ATOMIC_T\s0" 4 |
4863 | .IP "\s-1EV_ATOMIC_T\s0" 4 |
4446 | .IX Item "EV_ATOMIC_T" |
4864 | .IX Item "EV_ATOMIC_T" |
4447 | Libev requires an integer type (suitable for storing \f(CW0\fR or \f(CW1\fR) whose |
4865 | Libev requires an integer type (suitable for storing \f(CW0\fR or \f(CW1\fR) whose |
4448 | access is atomic with respect to other threads or signal contexts. No such |
4866 | access is atomic with respect to other threads or signal contexts. No |
4449 | type is easily found in the C language, so you can provide your own type |
4867 | such type is easily found in the C language, so you can provide your own |
4450 | that you know is safe for your purposes. It is used both for signal handler \*(L"locking\*(R" |
4868 | type that you know is safe for your purposes. It is used both for signal |
4451 | as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR watchers. |
4869 | handler \*(L"locking\*(R" as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR |
|
|
4870 | watchers. |
4452 | .Sp |
4871 | .Sp |
4453 | In the absence of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR |
4872 | In the absence of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR |
4454 | (from \fIsignal.h\fR), which is usually good enough on most platforms. |
4873 | (from \fIsignal.h\fR), which is usually good enough on most platforms. |
4455 | .IP "\s-1EV_H\s0 (h)" 4 |
4874 | .IP "\s-1EV_H\s0 (h)" 4 |
4456 | .IX Item "EV_H (h)" |
4875 | .IX Item "EV_H (h)" |
… | |
… | |
4477 | If undefined or defined to \f(CW1\fR, then all event-loop-specific functions |
4896 | If undefined or defined to \f(CW1\fR, then all event-loop-specific functions |
4478 | will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create |
4897 | will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create |
4479 | additional independent event loops. Otherwise there will be no support |
4898 | additional independent event loops. Otherwise there will be no support |
4480 | for multiple event loops and there is no first event loop pointer |
4899 | for multiple event loops and there is no first event loop pointer |
4481 | argument. Instead, all functions act on the single default loop. |
4900 | argument. Instead, all functions act on the single default loop. |
|
|
4901 | .Sp |
|
|
4902 | Note that \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR will no longer provide a |
|
|
4903 | default loop when multiplicity is switched off \- you always have to |
|
|
4904 | initialise the loop manually in this case. |
4482 | .IP "\s-1EV_MINPRI\s0" 4 |
4905 | .IP "\s-1EV_MINPRI\s0" 4 |
4483 | .IX Item "EV_MINPRI" |
4906 | .IX Item "EV_MINPRI" |
4484 | .PD 0 |
4907 | .PD 0 |
4485 | .IP "\s-1EV_MAXPRI\s0" 4 |
4908 | .IP "\s-1EV_MAXPRI\s0" 4 |
4486 | .IX Item "EV_MAXPRI" |
4909 | .IX Item "EV_MAXPRI" |
… | |
… | |
4494 | all the priorities, so having many of them (hundreds) uses a lot of space |
4917 | all the priorities, so having many of them (hundreds) uses a lot of space |
4495 | and time, so using the defaults of five priorities (\-2 .. +2) is usually |
4918 | and time, so using the defaults of five priorities (\-2 .. +2) is usually |
4496 | fine. |
4919 | fine. |
4497 | .Sp |
4920 | .Sp |
4498 | If your embedding application does not need any priorities, defining these |
4921 | If your embedding application does not need any priorities, defining these |
4499 | both to \f(CW0\fR will save some memory and \s-1CPU\s0. |
4922 | both to \f(CW0\fR will save some memory and \s-1CPU.\s0 |
4500 | .IP "\s-1EV_PERIODIC_ENABLE\s0, \s-1EV_IDLE_ENABLE\s0, \s-1EV_EMBED_ENABLE\s0, \s-1EV_STAT_ENABLE\s0, \s-1EV_PREPARE_ENABLE\s0, \s-1EV_CHECK_ENABLE\s0, \s-1EV_FORK_ENABLE\s0, \s-1EV_SIGNAL_ENABLE\s0, \s-1EV_ASYNC_ENABLE\s0, \s-1EV_CHILD_ENABLE\s0." 4 |
4923 | .IP "\s-1EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE, EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, EV_ASYNC_ENABLE, EV_CHILD_ENABLE.\s0" 4 |
4501 | .IX Item "EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE, EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, EV_ASYNC_ENABLE, EV_CHILD_ENABLE." |
4924 | .IX Item "EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE, EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, EV_ASYNC_ENABLE, EV_CHILD_ENABLE." |
4502 | If undefined or defined to be \f(CW1\fR (and the platform supports it), then |
4925 | If undefined or defined to be \f(CW1\fR (and the platform supports it), then |
4503 | the respective watcher type is supported. If defined to be \f(CW0\fR, then it |
4926 | the respective watcher type is supported. If defined to be \f(CW0\fR, then it |
4504 | is not. Disabling watcher types mainly saves code size. |
4927 | is not. Disabling watcher types mainly saves code size. |
4505 | .IP "\s-1EV_FEATURES\s0" 4 |
4928 | .IP "\s-1EV_FEATURES\s0" 4 |
… | |
… | |
4522 | \& #define EV_CHILD_ENABLE 1 |
4945 | \& #define EV_CHILD_ENABLE 1 |
4523 | \& #define EV_ASYNC_ENABLE 1 |
4946 | \& #define EV_ASYNC_ENABLE 1 |
4524 | .Ve |
4947 | .Ve |
4525 | .Sp |
4948 | .Sp |
4526 | The actual value is a bitset, it can be a combination of the following |
4949 | The actual value is a bitset, it can be a combination of the following |
4527 | values: |
4950 | values (by default, all of these are enabled): |
4528 | .RS 4 |
4951 | .RS 4 |
4529 | .ie n .IP "1 \- faster/larger code" 4 |
4952 | .ie n .IP "1 \- faster/larger code" 4 |
4530 | .el .IP "\f(CW1\fR \- faster/larger code" 4 |
4953 | .el .IP "\f(CW1\fR \- faster/larger code" 4 |
4531 | .IX Item "1 - faster/larger code" |
4954 | .IX Item "1 - faster/larger code" |
4532 | Use larger code to speed up some operations. |
4955 | Use larger code to speed up some operations. |
… | |
… | |
4535 | code size by roughly 30% on amd64). |
4958 | code size by roughly 30% on amd64). |
4536 | .Sp |
4959 | .Sp |
4537 | When optimising for size, use of compiler flags such as \f(CW\*(C`\-Os\*(C'\fR with |
4960 | When optimising for size, use of compiler flags such as \f(CW\*(C`\-Os\*(C'\fR with |
4538 | gcc is recommended, as well as \f(CW\*(C`\-DNDEBUG\*(C'\fR, as libev contains a number of |
4961 | gcc is recommended, as well as \f(CW\*(C`\-DNDEBUG\*(C'\fR, as libev contains a number of |
4539 | assertions. |
4962 | assertions. |
|
|
4963 | .Sp |
|
|
4964 | The default is off when \f(CW\*(C`_\|_OPTIMIZE_SIZE_\|_\*(C'\fR is defined by your compiler |
|
|
4965 | (e.g. gcc with \f(CW\*(C`\-Os\*(C'\fR). |
4540 | .ie n .IP "2 \- faster/larger data structures" 4 |
4966 | .ie n .IP "2 \- faster/larger data structures" 4 |
4541 | .el .IP "\f(CW2\fR \- faster/larger data structures" 4 |
4967 | .el .IP "\f(CW2\fR \- faster/larger data structures" 4 |
4542 | .IX Item "2 - faster/larger data structures" |
4968 | .IX Item "2 - faster/larger data structures" |
4543 | Replaces the small 2\-heap for timer management by a faster 4\-heap, larger |
4969 | Replaces the small 2\-heap for timer management by a faster 4\-heap, larger |
4544 | hash table sizes and so on. This will usually further increase code size |
4970 | hash table sizes and so on. This will usually further increase code size |
4545 | and can additionally have an effect on the size of data structures at |
4971 | and can additionally have an effect on the size of data structures at |
4546 | runtime. |
4972 | runtime. |
|
|
4973 | .Sp |
|
|
4974 | The default is off when \f(CW\*(C`_\|_OPTIMIZE_SIZE_\|_\*(C'\fR is defined by your compiler |
|
|
4975 | (e.g. gcc with \f(CW\*(C`\-Os\*(C'\fR). |
4547 | .ie n .IP "4 \- full \s-1API\s0 configuration" 4 |
4976 | .ie n .IP "4 \- full \s-1API\s0 configuration" 4 |
4548 | .el .IP "\f(CW4\fR \- full \s-1API\s0 configuration" 4 |
4977 | .el .IP "\f(CW4\fR \- full \s-1API\s0 configuration" 4 |
4549 | .IX Item "4 - full API configuration" |
4978 | .IX Item "4 - full API configuration" |
4550 | This enables priorities (sets \f(CW\*(C`EV_MAXPRI\*(C'\fR=2 and \f(CW\*(C`EV_MINPRI\*(C'\fR=\-2), and |
4979 | This enables priorities (sets \f(CW\*(C`EV_MAXPRI\*(C'\fR=2 and \f(CW\*(C`EV_MINPRI\*(C'\fR=\-2), and |
4551 | enables multiplicity (\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR=1). |
4980 | enables multiplicity (\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR=1). |
… | |
… | |
4583 | With an intelligent-enough linker (gcc+binutils are intelligent enough |
5012 | With an intelligent-enough linker (gcc+binutils are intelligent enough |
4584 | when you use \f(CW\*(C`\-Wl,\-\-gc\-sections \-ffunction\-sections\*(C'\fR) functions unused by |
5013 | when you use \f(CW\*(C`\-Wl,\-\-gc\-sections \-ffunction\-sections\*(C'\fR) functions unused by |
4585 | your program might be left out as well \- a binary starting a timer and an |
5014 | your program might be left out as well \- a binary starting a timer and an |
4586 | I/O watcher then might come out at only 5Kb. |
5015 | I/O watcher then might come out at only 5Kb. |
4587 | .RE |
5016 | .RE |
|
|
5017 | .IP "\s-1EV_API_STATIC\s0" 4 |
|
|
5018 | .IX Item "EV_API_STATIC" |
|
|
5019 | If this symbol is defined (by default it is not), then all identifiers |
|
|
5020 | will have static linkage. This means that libev will not export any |
|
|
5021 | identifiers, and you cannot link against libev anymore. This can be useful |
|
|
5022 | when you embed libev, only want to use libev functions in a single file, |
|
|
5023 | and do not want its identifiers to be visible. |
|
|
5024 | .Sp |
|
|
5025 | To use this, define \f(CW\*(C`EV_API_STATIC\*(C'\fR and include \fIev.c\fR in the file that |
|
|
5026 | wants to use libev. |
|
|
5027 | .Sp |
|
|
5028 | This option only works when libev is compiled with a C compiler, as \*(C+ |
|
|
5029 | doesn't support the required declaration syntax. |
4588 | .IP "\s-1EV_AVOID_STDIO\s0" 4 |
5030 | .IP "\s-1EV_AVOID_STDIO\s0" 4 |
4589 | .IX Item "EV_AVOID_STDIO" |
5031 | .IX Item "EV_AVOID_STDIO" |
4590 | If this is set to \f(CW1\fR at compiletime, then libev will avoid using stdio |
5032 | If this is set to \f(CW1\fR at compiletime, then libev will avoid using stdio |
4591 | functions (printf, scanf, perror etc.). This will increase the code size |
5033 | functions (printf, scanf, perror etc.). This will increase the code size |
4592 | somewhat, but if your program doesn't otherwise depend on stdio and your |
5034 | somewhat, but if your program doesn't otherwise depend on stdio and your |
… | |
… | |
4644 | called. If set to \f(CW2\fR, then the internal verification code will be |
5086 | called. If set to \f(CW2\fR, then the internal verification code will be |
4645 | called once per loop, which can slow down libev. If set to \f(CW3\fR, then the |
5087 | called once per loop, which can slow down libev. If set to \f(CW3\fR, then the |
4646 | verification code will be called very frequently, which will slow down |
5088 | verification code will be called very frequently, which will slow down |
4647 | libev considerably. |
5089 | libev considerably. |
4648 | .Sp |
5090 | .Sp |
|
|
5091 | Verification errors are reported via C's \f(CW\*(C`assert\*(C'\fR mechanism, so if you |
|
|
5092 | disable that (e.g. by defining \f(CW\*(C`NDEBUG\*(C'\fR) then no errors will be reported. |
|
|
5093 | .Sp |
4649 | The default is \f(CW1\fR, unless \f(CW\*(C`EV_FEATURES\*(C'\fR overrides it, in which case it |
5094 | The default is \f(CW1\fR, unless \f(CW\*(C`EV_FEATURES\*(C'\fR overrides it, in which case it |
4650 | will be \f(CW0\fR. |
5095 | will be \f(CW0\fR. |
4651 | .IP "\s-1EV_COMMON\s0" 4 |
5096 | .IP "\s-1EV_COMMON\s0" 4 |
4652 | .IX Item "EV_COMMON" |
5097 | .IX Item "EV_COMMON" |
4653 | By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining |
5098 | By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining |
… | |
… | |
4674 | and the way callbacks are invoked and set. Must expand to a struct member |
5119 | and the way callbacks are invoked and set. Must expand to a struct member |
4675 | definition and a statement, respectively. See the \fIev.h\fR header file for |
5120 | definition and a statement, respectively. See the \fIev.h\fR header file for |
4676 | their default definitions. One possible use for overriding these is to |
5121 | their default definitions. One possible use for overriding these is to |
4677 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
5122 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
4678 | method calls instead of plain function calls in \*(C+. |
5123 | method calls instead of plain function calls in \*(C+. |
4679 | .SS "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0" |
5124 | .SS "\s-1EXPORTED API SYMBOLS\s0" |
4680 | .IX Subsection "EXPORTED API SYMBOLS" |
5125 | .IX Subsection "EXPORTED API SYMBOLS" |
4681 | If you need to re-export the \s-1API\s0 (e.g. via a \s-1DLL\s0) and you need a list of |
5126 | If you need to re-export the \s-1API\s0 (e.g. via a \s-1DLL\s0) and you need a list of |
4682 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
5127 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
4683 | all public symbols, one per line: |
5128 | all public symbols, one per line: |
4684 | .PP |
5129 | .PP |
… | |
… | |
4738 | \& #include "ev_cpp.h" |
5183 | \& #include "ev_cpp.h" |
4739 | \& #include "ev.c" |
5184 | \& #include "ev.c" |
4740 | .Ve |
5185 | .Ve |
4741 | .SH "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT" |
5186 | .SH "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT" |
4742 | .IX Header "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT" |
5187 | .IX Header "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT" |
4743 | .SS "\s-1THREADS\s0 \s-1AND\s0 \s-1COROUTINES\s0" |
5188 | .SS "\s-1THREADS AND COROUTINES\s0" |
4744 | .IX Subsection "THREADS AND COROUTINES" |
5189 | .IX Subsection "THREADS AND COROUTINES" |
4745 | \fI\s-1THREADS\s0\fR |
5190 | \fI\s-1THREADS\s0\fR |
4746 | .IX Subsection "THREADS" |
5191 | .IX Subsection "THREADS" |
4747 | .PP |
5192 | .PP |
4748 | All libev functions are reentrant and thread-safe unless explicitly |
5193 | All libev functions are reentrant and thread-safe unless explicitly |
… | |
… | |
4794 | An example use would be to communicate signals or other events that only |
5239 | An example use would be to communicate signals or other events that only |
4795 | work in the default loop by registering the signal watcher with the |
5240 | work in the default loop by registering the signal watcher with the |
4796 | default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop |
5241 | default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop |
4797 | watcher callback into the event loop interested in the signal. |
5242 | watcher callback into the event loop interested in the signal. |
4798 | .PP |
5243 | .PP |
4799 | See also \*(L"\s-1THREAD\s0 \s-1LOCKING\s0 \s-1EXAMPLE\s0\*(R". |
5244 | See also \*(L"\s-1THREAD LOCKING EXAMPLE\*(R"\s0. |
4800 | .PP |
5245 | .PP |
4801 | \fI\s-1COROUTINES\s0\fR |
5246 | \fI\s-1COROUTINES\s0\fR |
4802 | .IX Subsection "COROUTINES" |
5247 | .IX Subsection "COROUTINES" |
4803 | .PP |
5248 | .PP |
4804 | Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"): |
5249 | Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"): |
… | |
… | |
4809 | that you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. |
5254 | that you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. |
4810 | .PP |
5255 | .PP |
4811 | Care has been taken to ensure that libev does not keep local state inside |
5256 | Care has been taken to ensure that libev does not keep local state inside |
4812 | \&\f(CW\*(C`ev_run\*(C'\fR, and other calls do not usually allow for coroutine switches as |
5257 | \&\f(CW\*(C`ev_run\*(C'\fR, and other calls do not usually allow for coroutine switches as |
4813 | they do not call any callbacks. |
5258 | they do not call any callbacks. |
4814 | .SS "\s-1COMPILER\s0 \s-1WARNINGS\s0" |
5259 | .SS "\s-1COMPILER WARNINGS\s0" |
4815 | .IX Subsection "COMPILER WARNINGS" |
5260 | .IX Subsection "COMPILER WARNINGS" |
4816 | Depending on your compiler and compiler settings, you might get no or a |
5261 | Depending on your compiler and compiler settings, you might get no or a |
4817 | lot of warnings when compiling libev code. Some people are apparently |
5262 | lot of warnings when compiling libev code. Some people are apparently |
4818 | scared by this. |
5263 | scared by this. |
4819 | .PP |
5264 | .PP |
… | |
… | |
4871 | .PP |
5316 | .PP |
4872 | If you need, for some reason, empty reports from valgrind for your project |
5317 | If you need, for some reason, empty reports from valgrind for your project |
4873 | I suggest using suppression lists. |
5318 | I suggest using suppression lists. |
4874 | .SH "PORTABILITY NOTES" |
5319 | .SH "PORTABILITY NOTES" |
4875 | .IX Header "PORTABILITY NOTES" |
5320 | .IX Header "PORTABILITY NOTES" |
4876 | .SS "\s-1GNU/LINUX\s0 32 \s-1BIT\s0 \s-1LIMITATIONS\s0" |
5321 | .SS "\s-1GNU/LINUX 32 BIT LIMITATIONS\s0" |
4877 | .IX Subsection "GNU/LINUX 32 BIT LIMITATIONS" |
5322 | .IX Subsection "GNU/LINUX 32 BIT LIMITATIONS" |
4878 | GNU/Linux is the only common platform that supports 64 bit file/large file |
5323 | GNU/Linux is the only common platform that supports 64 bit file/large file |
4879 | interfaces but \fIdisables\fR them by default. |
5324 | interfaces but \fIdisables\fR them by default. |
4880 | .PP |
5325 | .PP |
4881 | That means that libev compiled in the default environment doesn't support |
5326 | That means that libev compiled in the default environment doesn't support |
4882 | files larger than 2GiB or so, which mainly affects \f(CW\*(C`ev_stat\*(C'\fR watchers. |
5327 | files larger than 2GiB or so, which mainly affects \f(CW\*(C`ev_stat\*(C'\fR watchers. |
4883 | .PP |
5328 | .PP |
4884 | Unfortunately, many programs try to work around this GNU/Linux issue |
5329 | Unfortunately, many programs try to work around this GNU/Linux issue |
4885 | by enabling the large file \s-1API\s0, which makes them incompatible with the |
5330 | by enabling the large file \s-1API,\s0 which makes them incompatible with the |
4886 | standard libev compiled for their system. |
5331 | standard libev compiled for their system. |
4887 | .PP |
5332 | .PP |
4888 | Likewise, libev cannot enable the large file \s-1API\s0 itself as this would |
5333 | Likewise, libev cannot enable the large file \s-1API\s0 itself as this would |
4889 | suddenly make it incompatible to the default compile time environment, |
5334 | suddenly make it incompatible to the default compile time environment, |
4890 | i.e. all programs not using special compile switches. |
5335 | i.e. all programs not using special compile switches. |
4891 | .SS "\s-1OS/X\s0 \s-1AND\s0 \s-1DARWIN\s0 \s-1BUGS\s0" |
5336 | .SS "\s-1OS/X AND DARWIN BUGS\s0" |
4892 | .IX Subsection "OS/X AND DARWIN BUGS" |
5337 | .IX Subsection "OS/X AND DARWIN BUGS" |
4893 | The whole thing is a bug if you ask me \- basically any system interface |
5338 | The whole thing is a bug if you ask me \- basically any system interface |
4894 | you touch is broken, whether it is locales, poll, kqueue or even the |
5339 | you touch is broken, whether it is locales, poll, kqueue or even the |
4895 | OpenGL drivers. |
5340 | OpenGL drivers. |
4896 | .PP |
5341 | .PP |
… | |
… | |
4918 | .PP |
5363 | .PP |
4919 | \fI\f(CI\*(C`select\*(C'\fI is buggy\fR |
5364 | \fI\f(CI\*(C`select\*(C'\fI is buggy\fR |
4920 | .IX Subsection "select is buggy" |
5365 | .IX Subsection "select is buggy" |
4921 | .PP |
5366 | .PP |
4922 | All that's left is \f(CW\*(C`select\*(C'\fR, and of course Apple found a way to fuck this |
5367 | All that's left is \f(CW\*(C`select\*(C'\fR, and of course Apple found a way to fuck this |
4923 | one up as well: On \s-1OS/X\s0, \f(CW\*(C`select\*(C'\fR actively limits the number of file |
5368 | one up as well: On \s-1OS/X,\s0 \f(CW\*(C`select\*(C'\fR actively limits the number of file |
4924 | descriptors you can pass in to 1024 \- your program suddenly crashes when |
5369 | descriptors you can pass in to 1024 \- your program suddenly crashes when |
4925 | you use more. |
5370 | you use more. |
4926 | .PP |
5371 | .PP |
4927 | There is an undocumented \*(L"workaround\*(R" for this \- defining |
5372 | There is an undocumented \*(L"workaround\*(R" for this \- defining |
4928 | \&\f(CW\*(C`_DARWIN_UNLIMITED_SELECT\*(C'\fR, which libev tries to use, so select \fIshould\fR |
5373 | \&\f(CW\*(C`_DARWIN_UNLIMITED_SELECT\*(C'\fR, which libev tries to use, so select \fIshould\fR |
4929 | work on \s-1OS/X\s0. |
5374 | work on \s-1OS/X.\s0 |
4930 | .SS "\s-1SOLARIS\s0 \s-1PROBLEMS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" |
5375 | .SS "\s-1SOLARIS PROBLEMS AND WORKAROUNDS\s0" |
4931 | .IX Subsection "SOLARIS PROBLEMS AND WORKAROUNDS" |
5376 | .IX Subsection "SOLARIS PROBLEMS AND WORKAROUNDS" |
4932 | \fI\f(CI\*(C`errno\*(C'\fI reentrancy\fR |
5377 | \fI\f(CI\*(C`errno\*(C'\fI reentrancy\fR |
4933 | .IX Subsection "errno reentrancy" |
5378 | .IX Subsection "errno reentrancy" |
4934 | .PP |
5379 | .PP |
4935 | The default compile environment on Solaris is unfortunately so |
5380 | The default compile environment on Solaris is unfortunately so |
… | |
… | |
4952 | great. |
5397 | great. |
4953 | .PP |
5398 | .PP |
4954 | If you can't get it to work, you can try running the program by setting |
5399 | If you can't get it to work, you can try running the program by setting |
4955 | the environment variable \f(CW\*(C`LIBEV_FLAGS=3\*(C'\fR to only allow \f(CW\*(C`poll\*(C'\fR and |
5400 | the environment variable \f(CW\*(C`LIBEV_FLAGS=3\*(C'\fR to only allow \f(CW\*(C`poll\*(C'\fR and |
4956 | \&\f(CW\*(C`select\*(C'\fR backends. |
5401 | \&\f(CW\*(C`select\*(C'\fR backends. |
4957 | .SS "\s-1AIX\s0 \s-1POLL\s0 \s-1BUG\s0" |
5402 | .SS "\s-1AIX POLL BUG\s0" |
4958 | .IX Subsection "AIX POLL BUG" |
5403 | .IX Subsection "AIX POLL BUG" |
4959 | \&\s-1AIX\s0 unfortunately has a broken \f(CW\*(C`poll.h\*(C'\fR header. Libev works around |
5404 | \&\s-1AIX\s0 unfortunately has a broken \f(CW\*(C`poll.h\*(C'\fR header. Libev works around |
4960 | this by trying to avoid the poll backend altogether (i.e. it's not even |
5405 | this by trying to avoid the poll backend altogether (i.e. it's not even |
4961 | compiled in), which normally isn't a big problem as \f(CW\*(C`select\*(C'\fR works fine |
5406 | compiled in), which normally isn't a big problem as \f(CW\*(C`select\*(C'\fR works fine |
4962 | with large bitsets on \s-1AIX\s0, and \s-1AIX\s0 is dead anyway. |
5407 | with large bitsets on \s-1AIX,\s0 and \s-1AIX\s0 is dead anyway. |
4963 | .SS "\s-1WIN32\s0 \s-1PLATFORM\s0 \s-1LIMITATIONS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" |
5408 | .SS "\s-1WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS\s0" |
4964 | .IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS" |
5409 | .IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS" |
4965 | \fIGeneral issues\fR |
5410 | \fIGeneral issues\fR |
4966 | .IX Subsection "General issues" |
5411 | .IX Subsection "General issues" |
4967 | .PP |
5412 | .PP |
4968 | Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev |
5413 | Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev |
4969 | requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 |
5414 | requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 |
4970 | model. Libev still offers limited functionality on this platform in |
5415 | model. Libev still offers limited functionality on this platform in |
4971 | the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket |
5416 | the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket |
4972 | descriptors. This only applies when using Win32 natively, not when using |
5417 | descriptors. This only applies when using Win32 natively, not when using |
4973 | e.g. cygwin. Actually, it only applies to the microsofts own compilers, |
5418 | e.g. cygwin. Actually, it only applies to the microsofts own compilers, |
4974 | as every compielr comes with a slightly differently broken/incompatible |
5419 | as every compiler comes with a slightly differently broken/incompatible |
4975 | environment. |
5420 | environment. |
4976 | .PP |
5421 | .PP |
4977 | Lifting these limitations would basically require the full |
5422 | Lifting these limitations would basically require the full |
4978 | re-implementation of the I/O system. If you are into this kind of thing, |
5423 | re-implementation of the I/O system. If you are into this kind of thing, |
4979 | then note that glib does exactly that for you in a very portable way (note |
5424 | then note that glib does exactly that for you in a very portable way (note |
… | |
… | |
5037 | \& #define EV_USE_SELECT 1 |
5482 | \& #define EV_USE_SELECT 1 |
5038 | \& #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
5483 | \& #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
5039 | .Ve |
5484 | .Ve |
5040 | .PP |
5485 | .PP |
5041 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
5486 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
5042 | complexity in the O(nA\*^X) range when using win32. |
5487 | complexity in the O(nX) range when using win32. |
5043 | .PP |
5488 | .PP |
5044 | \fILimited number of file descriptors\fR |
5489 | \fILimited number of file descriptors\fR |
5045 | .IX Subsection "Limited number of file descriptors" |
5490 | .IX Subsection "Limited number of file descriptors" |
5046 | .PP |
5491 | .PP |
5047 | Windows has numerous arbitrary (and low) limits on things. |
5492 | Windows has numerous arbitrary (and low) limits on things. |
… | |
… | |
5063 | by calling \f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR |
5508 | by calling \f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR |
5064 | (another arbitrary limit), but is broken in many versions of the Microsoft |
5509 | (another arbitrary limit), but is broken in many versions of the Microsoft |
5065 | runtime libraries. This might get you to about \f(CW512\fR or \f(CW2048\fR sockets |
5510 | runtime libraries. This might get you to about \f(CW512\fR or \f(CW2048\fR sockets |
5066 | (depending on windows version and/or the phase of the moon). To get more, |
5511 | (depending on windows version and/or the phase of the moon). To get more, |
5067 | you need to wrap all I/O functions and provide your own fd management, but |
5512 | you need to wrap all I/O functions and provide your own fd management, but |
5068 | the cost of calling select (O(nA\*^X)) will likely make this unworkable. |
5513 | the cost of calling select (O(nX)) will likely make this unworkable. |
5069 | .SS "\s-1PORTABILITY\s0 \s-1REQUIREMENTS\s0" |
5514 | .SS "\s-1PORTABILITY REQUIREMENTS\s0" |
5070 | .IX Subsection "PORTABILITY REQUIREMENTS" |
5515 | .IX Subsection "PORTABILITY REQUIREMENTS" |
5071 | In addition to a working ISO-C implementation and of course the |
5516 | In addition to a working ISO-C implementation and of course the |
5072 | backend-specific APIs, libev relies on a few additional extensions: |
5517 | backend-specific APIs, libev relies on a few additional extensions: |
5073 | .ie n .IP """void (*)(ev_watcher_type *, int revents)"" must have compatible calling conventions regardless of ""ev_watcher_type *""." 4 |
5518 | .ie n .IP """void (*)(ev_watcher_type *, int revents)"" must have compatible calling conventions regardless of ""ev_watcher_type *""." 4 |
5074 | .el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4 |
5519 | .el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4 |
5075 | .IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *." |
5520 | .IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *." |
5076 | Libev assumes not only that all watcher pointers have the same internal |
5521 | Libev assumes not only that all watcher pointers have the same internal |
5077 | structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO\s0 C for example), but it also |
5522 | structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO C\s0 for example), but it also |
5078 | assumes that the same (machine) code can be used to call any watcher |
5523 | assumes that the same (machine) code can be used to call any watcher |
5079 | callback: The watcher callbacks have different type signatures, but libev |
5524 | callback: The watcher callbacks have different type signatures, but libev |
5080 | calls them using an \f(CW\*(C`ev_watcher *\*(C'\fR internally. |
5525 | calls them using an \f(CW\*(C`ev_watcher *\*(C'\fR internally. |
|
|
5526 | .IP "null pointers and integer zero are represented by 0 bytes" 4 |
|
|
5527 | .IX Item "null pointers and integer zero are represented by 0 bytes" |
|
|
5528 | Libev uses \f(CW\*(C`memset\*(C'\fR to initialise structs and arrays to \f(CW0\fR bytes, and |
|
|
5529 | relies on this setting pointers and integers to null. |
5081 | .IP "pointer accesses must be thread-atomic" 4 |
5530 | .IP "pointer accesses must be thread-atomic" 4 |
5082 | .IX Item "pointer accesses must be thread-atomic" |
5531 | .IX Item "pointer accesses must be thread-atomic" |
5083 | Accessing a pointer value must be atomic, it must both be readable and |
5532 | Accessing a pointer value must be atomic, it must both be readable and |
5084 | writable in one piece \- this is the case on all current architectures. |
5533 | writable in one piece \- this is the case on all current architectures. |
5085 | .ie n .IP """sig_atomic_t volatile"" must be thread-atomic as well" 4 |
5534 | .ie n .IP """sig_atomic_t volatile"" must be thread-atomic as well" 4 |
… | |
… | |
5098 | thread\*(R" or will block signals process-wide, both behaviours would |
5547 | thread\*(R" or will block signals process-wide, both behaviours would |
5099 | be compatible with libev. Interaction between \f(CW\*(C`sigprocmask\*(C'\fR and |
5548 | be compatible with libev. Interaction between \f(CW\*(C`sigprocmask\*(C'\fR and |
5100 | \&\f(CW\*(C`pthread_sigmask\*(C'\fR could complicate things, however. |
5549 | \&\f(CW\*(C`pthread_sigmask\*(C'\fR could complicate things, however. |
5101 | .Sp |
5550 | .Sp |
5102 | The most portable way to handle signals is to block signals in all threads |
5551 | The most portable way to handle signals is to block signals in all threads |
5103 | except the initial one, and run the default loop in the initial thread as |
5552 | except the initial one, and run the signal handling loop in the initial |
5104 | well. |
5553 | thread as well. |
5105 | .ie n .IP """long"" must be large enough for common memory allocation sizes" 4 |
5554 | .ie n .IP """long"" must be large enough for common memory allocation sizes" 4 |
5106 | .el .IP "\f(CWlong\fR must be large enough for common memory allocation sizes" 4 |
5555 | .el .IP "\f(CWlong\fR must be large enough for common memory allocation sizes" 4 |
5107 | .IX Item "long must be large enough for common memory allocation sizes" |
5556 | .IX Item "long must be large enough for common memory allocation sizes" |
5108 | To improve portability and simplify its \s-1API\s0, libev uses \f(CW\*(C`long\*(C'\fR internally |
5557 | To improve portability and simplify its \s-1API,\s0 libev uses \f(CW\*(C`long\*(C'\fR internally |
5109 | instead of \f(CW\*(C`size_t\*(C'\fR when allocating its data structures. On non-POSIX |
5558 | instead of \f(CW\*(C`size_t\*(C'\fR when allocating its data structures. On non-POSIX |
5110 | systems (Microsoft...) this might be unexpectedly low, but is still at |
5559 | systems (Microsoft...) this might be unexpectedly low, but is still at |
5111 | least 31 bits everywhere, which is enough for hundreds of millions of |
5560 | least 31 bits everywhere, which is enough for hundreds of millions of |
5112 | watchers. |
5561 | watchers. |
5113 | .ie n .IP """double"" must hold a time value in seconds with enough accuracy" 4 |
5562 | .ie n .IP """double"" must hold a time value in seconds with enough accuracy" 4 |
… | |
… | |
5115 | .IX Item "double must hold a time value in seconds with enough accuracy" |
5564 | .IX Item "double must hold a time value in seconds with enough accuracy" |
5116 | The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to |
5565 | The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to |
5117 | have at least 51 bits of mantissa (and 9 bits of exponent), which is |
5566 | have at least 51 bits of mantissa (and 9 bits of exponent), which is |
5118 | good enough for at least into the year 4000 with millisecond accuracy |
5567 | good enough for at least into the year 4000 with millisecond accuracy |
5119 | (the design goal for libev). This requirement is overfulfilled by |
5568 | (the design goal for libev). This requirement is overfulfilled by |
5120 | implementations using \s-1IEEE\s0 754, which is basically all existing ones. With |
5569 | implementations using \s-1IEEE 754,\s0 which is basically all existing ones. |
|
|
5570 | .Sp |
5121 | \&\s-1IEEE\s0 754 doubles, you get microsecond accuracy until at least 2200. |
5571 | With \s-1IEEE 754\s0 doubles, you get microsecond accuracy until at least the |
|
|
5572 | year 2255 (and millisecond accuracy till the year 287396 \- by then, libev |
|
|
5573 | is either obsolete or somebody patched it to use \f(CW\*(C`long double\*(C'\fR or |
|
|
5574 | something like that, just kidding). |
5122 | .PP |
5575 | .PP |
5123 | If you know of other additional requirements drop me a note. |
5576 | If you know of other additional requirements drop me a note. |
5124 | .SH "ALGORITHMIC COMPLEXITIES" |
5577 | .SH "ALGORITHMIC COMPLEXITIES" |
5125 | .IX Header "ALGORITHMIC COMPLEXITIES" |
5578 | .IX Header "ALGORITHMIC COMPLEXITIES" |
5126 | In this section the complexities of (many of) the algorithms used inside |
5579 | In this section the complexities of (many of) the algorithms used inside |
… | |
… | |
5180 | .IX Item "Processing ev_async_send: O(number_of_async_watchers)" |
5633 | .IX Item "Processing ev_async_send: O(number_of_async_watchers)" |
5181 | .IP "Processing signals: O(max_signal_number)" 4 |
5634 | .IP "Processing signals: O(max_signal_number)" 4 |
5182 | .IX Item "Processing signals: O(max_signal_number)" |
5635 | .IX Item "Processing signals: O(max_signal_number)" |
5183 | .PD |
5636 | .PD |
5184 | Sending involves a system call \fIiff\fR there were no other \f(CW\*(C`ev_async_send\*(C'\fR |
5637 | Sending involves a system call \fIiff\fR there were no other \f(CW\*(C`ev_async_send\*(C'\fR |
5185 | calls in the current loop iteration. Checking for async and signal events |
5638 | calls in the current loop iteration and the loop is currently |
|
|
5639 | blocked. Checking for async and signal events involves iterating over all |
5186 | involves iterating over all running async watchers or all signal numbers. |
5640 | running async watchers or all signal numbers. |
5187 | .SH "PORTING FROM LIBEV 3.X TO 4.X" |
5641 | .SH "PORTING FROM LIBEV 3.X TO 4.X" |
5188 | .IX Header "PORTING FROM LIBEV 3.X TO 4.X" |
5642 | .IX Header "PORTING FROM LIBEV 3.X TO 4.X" |
5189 | The major version 4 introduced some incompatible changes to the \s-1API\s0. |
5643 | The major version 4 introduced some incompatible changes to the \s-1API.\s0 |
5190 | .PP |
5644 | .PP |
5191 | At the moment, the \f(CW\*(C`ev.h\*(C'\fR header file provides compatibility definitions |
5645 | At the moment, the \f(CW\*(C`ev.h\*(C'\fR header file provides compatibility definitions |
5192 | for all changes, so most programs should still compile. The compatibility |
5646 | for all changes, so most programs should still compile. The compatibility |
5193 | layer might be removed in later versions of libev, so better update to the |
5647 | layer might be removed in later versions of libev, so better update to the |
5194 | new \s-1API\s0 early than late. |
5648 | new \s-1API\s0 early than late. |
5195 | .ie n .IP """EV_COMPAT3"" backwards compatibility mechanism" 4 |
5649 | .ie n .IP """EV_COMPAT3"" backwards compatibility mechanism" 4 |
5196 | .el .IP "\f(CWEV_COMPAT3\fR backwards compatibility mechanism" 4 |
5650 | .el .IP "\f(CWEV_COMPAT3\fR backwards compatibility mechanism" 4 |
5197 | .IX Item "EV_COMPAT3 backwards compatibility mechanism" |
5651 | .IX Item "EV_COMPAT3 backwards compatibility mechanism" |
5198 | The backward compatibility mechanism can be controlled by |
5652 | The backward compatibility mechanism can be controlled by |
5199 | \&\f(CW\*(C`EV_COMPAT3\*(C'\fR. See \*(L"\s-1MACROS\s0\*(R" in \s-1PREPROCESSOR\s0 \s-1SYMBOLS\s0 in the \s-1EMBEDDING\s0 |
5653 | \&\f(CW\*(C`EV_COMPAT3\*(C'\fR. See \*(L"\s-1PREPROCESSOR SYMBOLS/MACROS\*(R"\s0 in the \*(L"\s-1EMBEDDING\*(R"\s0 |
5200 | section. |
5654 | section. |
5201 | .ie n .IP """ev_default_destroy"" and ""ev_default_fork"" have been removed" 4 |
5655 | .ie n .IP """ev_default_destroy"" and ""ev_default_fork"" have been removed" 4 |
5202 | .el .IP "\f(CWev_default_destroy\fR and \f(CWev_default_fork\fR have been removed" 4 |
5656 | .el .IP "\f(CWev_default_destroy\fR and \f(CWev_default_fork\fR have been removed" 4 |
5203 | .IX Item "ev_default_destroy and ev_default_fork have been removed" |
5657 | .IX Item "ev_default_destroy and ev_default_fork have been removed" |
5204 | These calls can be replaced easily by their \f(CW\*(C`ev_loop_xxx\*(C'\fR counterparts: |
5658 | These calls can be replaced easily by their \f(CW\*(C`ev_loop_xxx\*(C'\fR counterparts: |
… | |
… | |
5244 | .SH "GLOSSARY" |
5698 | .SH "GLOSSARY" |
5245 | .IX Header "GLOSSARY" |
5699 | .IX Header "GLOSSARY" |
5246 | .IP "active" 4 |
5700 | .IP "active" 4 |
5247 | .IX Item "active" |
5701 | .IX Item "active" |
5248 | A watcher is active as long as it has been started and not yet stopped. |
5702 | A watcher is active as long as it has been started and not yet stopped. |
5249 | See \*(L"\s-1WATCHER\s0 \s-1STATES\s0\*(R" for details. |
5703 | See \*(L"\s-1WATCHER STATES\*(R"\s0 for details. |
5250 | .IP "application" 4 |
5704 | .IP "application" 4 |
5251 | .IX Item "application" |
5705 | .IX Item "application" |
5252 | In this document, an application is whatever is using libev. |
5706 | In this document, an application is whatever is using libev. |
5253 | .IP "backend" 4 |
5707 | .IP "backend" 4 |
5254 | .IX Item "backend" |
5708 | .IX Item "backend" |
… | |
… | |
5281 | The model used to describe how an event loop handles and processes |
5735 | The model used to describe how an event loop handles and processes |
5282 | watchers and events. |
5736 | watchers and events. |
5283 | .IP "pending" 4 |
5737 | .IP "pending" 4 |
5284 | .IX Item "pending" |
5738 | .IX Item "pending" |
5285 | A watcher is pending as soon as the corresponding event has been |
5739 | A watcher is pending as soon as the corresponding event has been |
5286 | detected. See \*(L"\s-1WATCHER\s0 \s-1STATES\s0\*(R" for details. |
5740 | detected. See \*(L"\s-1WATCHER STATES\*(R"\s0 for details. |
5287 | .IP "real time" 4 |
5741 | .IP "real time" 4 |
5288 | .IX Item "real time" |
5742 | .IX Item "real time" |
5289 | The physical time that is observed. It is apparently strictly monotonic :) |
5743 | The physical time that is observed. It is apparently strictly monotonic :) |
5290 | .IP "wall-clock time" 4 |
5744 | .IP "wall-clock time" 4 |
5291 | .IX Item "wall-clock time" |
5745 | .IX Item "wall-clock time" |
5292 | The time and date as shown on clocks. Unlike real time, it can actually |
5746 | The time and date as shown on clocks. Unlike real time, it can actually |
5293 | be wrong and jump forwards and backwards, e.g. when the you adjust your |
5747 | be wrong and jump forwards and backwards, e.g. when you adjust your |
5294 | clock. |
5748 | clock. |
5295 | .IP "watcher" 4 |
5749 | .IP "watcher" 4 |
5296 | .IX Item "watcher" |
5750 | .IX Item "watcher" |
5297 | A data structure that describes interest in certain events. Watchers need |
5751 | A data structure that describes interest in certain events. Watchers need |
5298 | to be started (attached to an event loop) before they can receive events. |
5752 | to be started (attached to an event loop) before they can receive events. |
5299 | .SH "AUTHOR" |
5753 | .SH "AUTHOR" |
5300 | .IX Header "AUTHOR" |
5754 | .IX Header "AUTHOR" |
5301 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael |
5755 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael |
5302 | Magnusson and Emanuele Giaquinta. |
5756 | Magnusson and Emanuele Giaquinta, and minor corrections by many others. |