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124 | .\" ======================================================================== |
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134 | .\" |
126 | .IX Title "LIBEV 3" |
135 | .IX Title "LIBEV 3" |
127 | .TH LIBEV 3 "2010-11-03" "libev-4.01" "libev - high performance full featured event loop" |
136 | .TH LIBEV 3 "2017-11-14" "libev-4.24" "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. |
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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. |
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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 |
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294 | .IP "ev_tstamp ev_time ()" 4 |
303 | .IP "ev_tstamp ev_time ()" 4 |
295 | .IX Item "ev_tstamp ev_time ()" |
304 | .IX Item "ev_tstamp ev_time ()" |
296 | Returns the current time as libev would use it. Please note that the |
305 | 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 |
306 | \&\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 |
307 | 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. |
308 | \&\f(CW\*(C`ev_now_update\*(C'\fR and \f(CW\*(C`ev_now\*(C'\fR. |
300 | .IP "ev_sleep (ev_tstamp interval)" 4 |
309 | .IP "ev_sleep (ev_tstamp interval)" 4 |
301 | .IX Item "ev_sleep (ev_tstamp interval)" |
310 | .IX Item "ev_sleep (ev_tstamp interval)" |
302 | Sleep for the given interval: The current thread will be blocked until |
311 | Sleep for the given interval: The current thread will be blocked |
303 | either it is interrupted or the given time interval has passed. Basically |
312 | until either it is interrupted or the given time interval has |
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313 | passed (approximately \- it might return a bit earlier even if not |
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314 | interrupted). Returns immediately if \f(CW\*(C`interval <= 0\*(C'\fR. |
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315 | .Sp |
304 | this is a sub-second-resolution \f(CW\*(C`sleep ()\*(C'\fR. |
316 | Basically this is a sub-second-resolution \f(CW\*(C`sleep ()\*(C'\fR. |
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317 | .Sp |
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318 | The range of the \f(CW\*(C`interval\*(C'\fR is limited \- libev only guarantees to work |
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319 | with sleep times of up to one day (\f(CW\*(C`interval <= 86400\*(C'\fR). |
305 | .IP "int ev_version_major ()" 4 |
320 | .IP "int ev_version_major ()" 4 |
306 | .IX Item "int ev_version_major ()" |
321 | .IX Item "int ev_version_major ()" |
307 | .PD 0 |
322 | .PD 0 |
308 | .IP "int ev_version_minor ()" 4 |
323 | .IP "int ev_version_minor ()" 4 |
309 | .IX Item "int ev_version_minor ()" |
324 | .IX Item "int ev_version_minor ()" |
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361 | current system. To find which embeddable backends might be supported on |
376 | 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 () |
377 | 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. |
378 | & ev_supported_backends ()\*(C'\fR, likewise for recommended ones. |
364 | .Sp |
379 | .Sp |
365 | See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
380 | 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 |
381 | .IP "ev_set_allocator (void *(*cb)(void *ptr, long size) throw ())" 4 |
367 | .IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))" |
382 | .IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size) throw ())" |
368 | Sets the allocation function to use (the prototype is similar \- the |
383 | 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 |
384 | 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 |
385 | 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 |
386 | when memory needs to be allocated (\f(CW\*(C`size != 0\*(C'\fR), the library might abort |
372 | or take some potentially destructive action. |
387 | or take some potentially destructive action. |
… | |
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398 | \& } |
413 | \& } |
399 | \& |
414 | \& |
400 | \& ... |
415 | \& ... |
401 | \& ev_set_allocator (persistent_realloc); |
416 | \& ev_set_allocator (persistent_realloc); |
402 | .Ve |
417 | .Ve |
403 | .IP "ev_set_syserr_cb (void (*cb)(const char *msg))" 4 |
418 | .IP "ev_set_syserr_cb (void (*cb)(const char *msg) throw ())" 4 |
404 | .IX Item "ev_set_syserr_cb (void (*cb)(const char *msg))" |
419 | .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 |
420 | 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 |
421 | as failed select, poll, epoll_wait). The message is a printable string |
407 | indicating the system call or subsystem causing the problem. If this |
422 | 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 |
423 | 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 |
424 | matter what, when it returns. That is, libev will generally retry the |
… | |
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421 | \& } |
436 | \& } |
422 | \& |
437 | \& |
423 | \& ... |
438 | \& ... |
424 | \& ev_set_syserr_cb (fatal_error); |
439 | \& ev_set_syserr_cb (fatal_error); |
425 | .Ve |
440 | .Ve |
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441 | .IP "ev_feed_signal (int signum)" 4 |
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442 | .IX Item "ev_feed_signal (int signum)" |
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443 | This function can be used to \*(L"simulate\*(R" a signal receive. It is completely |
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444 | safe to call this function at any time, from any context, including signal |
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445 | handlers or random threads. |
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446 | .Sp |
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447 | Its main use is to customise signal handling in your process, especially |
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448 | in the presence of threads. For example, you could block signals |
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449 | by default in all threads (and specifying \f(CW\*(C`EVFLAG_NOSIGMASK\*(C'\fR when |
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450 | creating any loops), and in one thread, use \f(CW\*(C`sigwait\*(C'\fR or any other |
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451 | mechanism to wait for signals, then \*(L"deliver\*(R" them to libev by calling |
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452 | \&\f(CW\*(C`ev_feed_signal\*(C'\fR. |
426 | .SH "FUNCTIONS CONTROLLING EVENT LOOPS" |
453 | .SH "FUNCTIONS CONTROLLING EVENT LOOPS" |
427 | .IX Header "FUNCTIONS CONTROLLING EVENT LOOPS" |
454 | .IX Header "FUNCTIONS CONTROLLING EVENT LOOPS" |
428 | An event loop is described by a \f(CW\*(C`struct ev_loop *\*(C'\fR (the \f(CW\*(C`struct\*(C'\fR is |
455 | An event loop is described by a \f(CW\*(C`struct ev_loop *\*(C'\fR (the \f(CW\*(C`struct\*(C'\fR is |
429 | \&\fInot\fR optional in this case unless libev 3 compatibility is disabled, as |
456 | \&\fInot\fR optional in this case unless libev 3 compatibility is disabled, as |
430 | libev 3 had an \f(CW\*(C`ev_loop\*(C'\fR function colliding with the struct name). |
457 | libev 3 had an \f(CW\*(C`ev_loop\*(C'\fR function colliding with the struct name). |
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475 | .IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4 |
502 | .IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4 |
476 | .IX Item "struct ev_loop *ev_loop_new (unsigned int flags)" |
503 | .IX Item "struct ev_loop *ev_loop_new (unsigned int flags)" |
477 | This will create and initialise a new event loop object. If the loop |
504 | This will create and initialise a new event loop object. If the loop |
478 | could not be initialised, returns false. |
505 | could not be initialised, returns false. |
479 | .Sp |
506 | .Sp |
480 | Note that this function \fIis\fR thread-safe, and one common way to use |
507 | This function is thread-safe, and one common way to use libev with |
481 | libev with threads is indeed to create one loop per thread, and using the |
508 | threads is indeed to create one loop per thread, and using the default |
482 | default loop in the \*(L"main\*(R" or \*(L"initial\*(R" thread. |
509 | loop in the \*(L"main\*(R" or \*(L"initial\*(R" thread. |
483 | .Sp |
510 | .Sp |
484 | The flags argument can be used to specify special behaviour or specific |
511 | The flags argument can be used to specify special behaviour or specific |
485 | backends to use, and is usually specified as \f(CW0\fR (or \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). |
512 | backends to use, and is usually specified as \f(CW0\fR (or \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). |
486 | .Sp |
513 | .Sp |
487 | The following flags are supported: |
514 | The following flags are supported: |
… | |
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496 | .IX Item "EVFLAG_NOENV" |
523 | .IX Item "EVFLAG_NOENV" |
497 | If this flag bit is or'ed into the flag value (or the program runs setuid |
524 | If this flag bit is or'ed into the flag value (or the program runs setuid |
498 | or setgid) then libev will \fInot\fR look at the environment variable |
525 | or setgid) then libev will \fInot\fR look at the environment variable |
499 | \&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will |
526 | \&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will |
500 | override the flags completely if it is found in the environment. This is |
527 | override the flags completely if it is found in the environment. This is |
501 | useful to try out specific backends to test their performance, or to work |
528 | useful to try out specific backends to test their performance, to work |
502 | around bugs. |
529 | around bugs, or to make libev threadsafe (accessing environment variables |
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530 | cannot be done in a threadsafe way, but usually it works if no other |
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531 | thread modifies them). |
503 | .ie n .IP """EVFLAG_FORKCHECK""" 4 |
532 | .ie n .IP """EVFLAG_FORKCHECK""" 4 |
504 | .el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4 |
533 | .el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4 |
505 | .IX Item "EVFLAG_FORKCHECK" |
534 | .IX Item "EVFLAG_FORKCHECK" |
506 | Instead of calling \f(CW\*(C`ev_loop_fork\*(C'\fR manually after a fork, you can also |
535 | Instead of calling \f(CW\*(C`ev_loop_fork\*(C'\fR manually after a fork, you can also |
507 | make libev check for a fork in each iteration by enabling this flag. |
536 | make libev check for a fork in each iteration by enabling this flag. |
508 | .Sp |
537 | .Sp |
509 | This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop, |
538 | This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop, |
510 | and thus this might slow down your event loop if you do a lot of loop |
539 | and thus this might slow down your event loop if you do a lot of loop |
511 | iterations and little real work, but is usually not noticeable (on my |
540 | iterations and little real work, but is usually not noticeable (on my |
512 | GNU/Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence |
541 | GNU/Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn |
513 | without a system call and thus \fIvery\fR fast, but my GNU/Linux system also has |
542 | sequence without a system call and thus \fIvery\fR fast, but my GNU/Linux |
514 | \&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster). |
543 | system also has \f(CW\*(C`pthread_atfork\*(C'\fR which is even faster). (Update: glibc |
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544 | versions 2.25 apparently removed the \f(CW\*(C`getpid\*(C'\fR optimisation again). |
515 | .Sp |
545 | .Sp |
516 | The big advantage of this flag is that you can forget about fork (and |
546 | The big advantage of this flag is that you can forget about fork (and |
517 | forget about forgetting to tell libev about forking) when you use this |
547 | forget about forgetting to tell libev about forking, although you still |
518 | flag. |
548 | have to ignore \f(CW\*(C`SIGPIPE\*(C'\fR) when you use this flag. |
519 | .Sp |
549 | .Sp |
520 | This flag setting cannot be overridden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR |
550 | This flag setting cannot be overridden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR |
521 | environment variable. |
551 | environment variable. |
522 | .ie n .IP """EVFLAG_NOINOTIFY""" 4 |
552 | .ie n .IP """EVFLAG_NOINOTIFY""" 4 |
523 | .el .IP "\f(CWEVFLAG_NOINOTIFY\fR" 4 |
553 | .el .IP "\f(CWEVFLAG_NOINOTIFY\fR" 4 |
… | |
… | |
537 | threads that are not interested in handling them. |
567 | threads that are not interested in handling them. |
538 | .Sp |
568 | .Sp |
539 | Signalfd will not be used by default as this changes your signal mask, and |
569 | Signalfd will not be used by default as this changes your signal mask, and |
540 | there are a lot of shoddy libraries and programs (glib's threadpool for |
570 | there are a lot of shoddy libraries and programs (glib's threadpool for |
541 | example) that can't properly initialise their signal masks. |
571 | example) that can't properly initialise their signal masks. |
|
|
572 | .ie n .IP """EVFLAG_NOSIGMASK""" 4 |
|
|
573 | .el .IP "\f(CWEVFLAG_NOSIGMASK\fR" 4 |
|
|
574 | .IX Item "EVFLAG_NOSIGMASK" |
|
|
575 | When this flag is specified, then libev will avoid to modify the signal |
|
|
576 | mask. Specifically, this means you have to make sure signals are unblocked |
|
|
577 | when you want to receive them. |
|
|
578 | .Sp |
|
|
579 | This behaviour is useful when you want to do your own signal handling, or |
|
|
580 | want to handle signals only in specific threads and want to avoid libev |
|
|
581 | unblocking the signals. |
|
|
582 | .Sp |
|
|
583 | It's also required by \s-1POSIX\s0 in a threaded program, as libev calls |
|
|
584 | \&\f(CW\*(C`sigprocmask\*(C'\fR, whose behaviour is officially unspecified. |
|
|
585 | .Sp |
|
|
586 | This flag's behaviour will become the default in future versions of libev. |
542 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
587 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
543 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
588 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
544 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
589 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
545 | This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
590 | This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
546 | libev tries to roll its own fd_set with no limits on the number of fds, |
591 | libev tries to roll its own fd_set with no limits on the number of fds, |
547 | but if that fails, expect a fairly low limit on the number of fds when |
592 | but if that fails, expect a fairly low limit on the number of fds when |
548 | using this backend. It doesn't scale too well (O(highest_fd)), but its |
593 | using this backend. It doesn't scale too well (O(highest_fd)), but its |
549 | usually the fastest backend for a low number of (low-numbered :) fds. |
594 | usually the fastest backend for a low number of (low-numbered :) fds. |
… | |
… | |
558 | 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 |
603 | 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 |
559 | \&\f(CW\*(C`writefds\*(C'\fR set (and to work around Microsoft Windows bugs, also onto the |
604 | \&\f(CW\*(C`writefds\*(C'\fR set (and to work around Microsoft Windows bugs, also onto the |
560 | \&\f(CW\*(C`exceptfds\*(C'\fR set on that platform). |
605 | \&\f(CW\*(C`exceptfds\*(C'\fR set on that platform). |
561 | .ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4 |
606 | .ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4 |
562 | .el .IP "\f(CWEVBACKEND_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4 |
607 | .el .IP "\f(CWEVBACKEND_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4 |
563 | .IX Item "EVBACKEND_POLL (value 2, poll backend, available everywhere except on windows)" |
608 | .IX Item "EVBACKEND_POLL (value 2, poll backend, available everywhere except on windows)" |
564 | And this is your standard \fIpoll\fR\|(2) backend. It's more complicated |
609 | And this is your standard \fIpoll\fR\|(2) backend. It's more complicated |
565 | than select, but handles sparse fds better and has no artificial |
610 | than select, but handles sparse fds better and has no artificial |
566 | limit on the number of fds you can use (except it will slow down |
611 | limit on the number of fds you can use (except it will slow down |
567 | considerably with a lot of inactive fds). It scales similarly to select, |
612 | considerably with a lot of inactive fds). It scales similarly to select, |
568 | i.e. O(total_fds). See the entry for \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR, above, for |
613 | i.e. O(total_fds). See the entry for \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR, above, for |
… | |
… | |
570 | .Sp |
615 | .Sp |
571 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR to \f(CW\*(C`POLLIN | POLLERR | POLLHUP\*(C'\fR, and |
616 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR to \f(CW\*(C`POLLIN | POLLERR | POLLHUP\*(C'\fR, and |
572 | \&\f(CW\*(C`EV_WRITE\*(C'\fR to \f(CW\*(C`POLLOUT | POLLERR | POLLHUP\*(C'\fR. |
617 | \&\f(CW\*(C`EV_WRITE\*(C'\fR to \f(CW\*(C`POLLOUT | POLLERR | POLLHUP\*(C'\fR. |
573 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
618 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
574 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
619 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
575 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
620 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
576 | Use the linux-specific \fIepoll\fR\|(7) interface (for both pre\- and post\-2.6.9 |
621 | Use the linux-specific \fIepoll\fR\|(7) interface (for both pre\- and post\-2.6.9 |
577 | kernels). |
622 | kernels). |
578 | .Sp |
623 | .Sp |
579 | For few fds, this backend is a bit little slower than poll and select, |
624 | For few fds, this backend is a bit little slower than poll and select, but |
580 | but it scales phenomenally better. While poll and select usually scale |
625 | it scales phenomenally better. While poll and select usually scale like |
581 | like O(total_fds) where n is the total number of fds (or the highest fd), |
626 | O(total_fds) where total_fds is the total number of fds (or the highest |
582 | epoll scales either O(1) or O(active_fds). |
627 | fd), epoll scales either O(1) or O(active_fds). |
583 | .Sp |
628 | .Sp |
584 | The epoll mechanism deserves honorable mention as the most misdesigned |
629 | The epoll mechanism deserves honorable mention as the most misdesigned |
585 | of the more advanced event mechanisms: mere annoyances include silently |
630 | of the more advanced event mechanisms: mere annoyances include silently |
586 | dropping file descriptors, requiring a system call per change per file |
631 | dropping file descriptors, requiring a system call per change per file |
587 | descriptor (and unnecessary guessing of parameters), problems with dup, |
632 | descriptor (and unnecessary guessing of parameters), problems with dup, |
… | |
… | |
590 | 0.1ms) and so on. The biggest issue is fork races, however \- if a program |
635 | 0.1ms) and so on. The biggest issue is fork races, however \- if a program |
591 | forks then \fIboth\fR parent and child process have to recreate the epoll |
636 | forks then \fIboth\fR parent and child process have to recreate the epoll |
592 | set, which can take considerable time (one syscall per file descriptor) |
637 | set, which can take considerable time (one syscall per file descriptor) |
593 | and is of course hard to detect. |
638 | and is of course hard to detect. |
594 | .Sp |
639 | .Sp |
595 | Epoll is also notoriously buggy \- embedding epoll fds \fIshould\fR work, but |
640 | Epoll is also notoriously buggy \- embedding epoll fds \fIshould\fR work, |
596 | of course \fIdoesn't\fR, and epoll just loves to report events for totally |
641 | but of course \fIdoesn't\fR, and epoll just loves to report events for |
597 | \&\fIdifferent\fR file descriptors (even already closed ones, so one cannot |
642 | totally \fIdifferent\fR file descriptors (even already closed ones, so |
598 | even remove them from the set) than registered in the set (especially |
643 | one cannot even remove them from the set) than registered in the set |
599 | on \s-1SMP\s0 systems). Libev tries to counter these spurious notifications by |
644 | (especially on \s-1SMP\s0 systems). Libev tries to counter these spurious |
600 | employing an additional generation counter and comparing that against the |
645 | notifications by employing an additional generation counter and comparing |
601 | events to filter out spurious ones, recreating the set when required. Last |
646 | that against the events to filter out spurious ones, recreating the set |
|
|
647 | when required. Epoll also erroneously rounds down timeouts, but gives you |
|
|
648 | no way to know when and by how much, so sometimes you have to busy-wait |
|
|
649 | because epoll returns immediately despite a nonzero timeout. And last |
602 | not least, it also refuses to work with some file descriptors which work |
650 | not least, it also refuses to work with some file descriptors which work |
603 | perfectly fine with \f(CW\*(C`select\*(C'\fR (files, many character devices...). |
651 | perfectly fine with \f(CW\*(C`select\*(C'\fR (files, many character devices...). |
604 | .Sp |
652 | .Sp |
605 | Epoll is truly the train wreck analog among event poll mechanisms. |
653 | Epoll is truly the train wreck among event poll mechanisms, a frankenpoll, |
|
|
654 | cobbled together in a hurry, no thought to design or interaction with |
|
|
655 | others. Oh, the pain, will it ever stop... |
606 | .Sp |
656 | .Sp |
607 | While stopping, setting and starting an I/O watcher in the same iteration |
657 | While stopping, setting and starting an I/O watcher in the same iteration |
608 | will result in some caching, there is still a system call per such |
658 | will result in some caching, there is still a system call per such |
609 | incident (because the same \fIfile descriptor\fR could point to a different |
659 | incident (because the same \fIfile descriptor\fR could point to a different |
610 | \&\fIfile description\fR now), so its best to avoid that. Also, \f(CW\*(C`dup ()\*(C'\fR'ed |
660 | \&\fIfile description\fR now), so its best to avoid that. Also, \f(CW\*(C`dup ()\*(C'\fR'ed |
… | |
… | |
628 | .Sp |
678 | .Sp |
629 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
679 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
630 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
680 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
631 | .ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 |
681 | .ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 |
632 | .el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 |
682 | .el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 |
633 | .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" |
683 | .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" |
634 | Kqueue deserves special mention, as at the time of this writing, it |
684 | Kqueue deserves special mention, as at the time of this writing, it |
635 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
685 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
636 | with anything but sockets and pipes, except on Darwin, where of course |
686 | with anything but sockets and pipes, except on Darwin, where of course |
637 | it's completely useless). Unlike epoll, however, whose brokenness |
687 | it's completely useless). Unlike epoll, however, whose brokenness |
638 | is by design, these kqueue bugs can (and eventually will) be fixed |
688 | is by design, these kqueue bugs can (and eventually will) be fixed |
… | |
… | |
647 | .Sp |
697 | .Sp |
648 | It scales in the same way as the epoll backend, but the interface to the |
698 | It scales in the same way as the epoll backend, but the interface to the |
649 | kernel is more efficient (which says nothing about its actual speed, of |
699 | kernel is more efficient (which says nothing about its actual speed, of |
650 | course). While stopping, setting and starting an I/O watcher does never |
700 | course). While stopping, setting and starting an I/O watcher does never |
651 | cause an extra system call as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to |
701 | cause an extra system call as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to |
652 | two event changes per incident. Support for \f(CW\*(C`fork ()\*(C'\fR is very bad (but |
702 | two event changes per incident. Support for \f(CW\*(C`fork ()\*(C'\fR is very bad (you |
653 | sane, unlike epoll) and it drops fds silently in similarly hard-to-detect |
703 | might have to leak fd's on fork, but it's more sane than epoll) and it |
654 | cases |
704 | drops fds silently in similarly hard-to-detect cases. |
655 | .Sp |
705 | .Sp |
656 | This backend usually performs well under most conditions. |
706 | This backend usually performs well under most conditions. |
657 | .Sp |
707 | .Sp |
658 | While nominally embeddable in other event loops, this doesn't work |
708 | While nominally embeddable in other event loops, this doesn't work |
659 | everywhere, so you might need to test for this. And since it is broken |
709 | everywhere, so you might need to test for this. And since it is broken |
660 | almost everywhere, you should only use it when you have a lot of sockets |
710 | almost everywhere, you should only use it when you have a lot of sockets |
661 | (for which it usually works), by embedding it into another event loop |
711 | (for which it usually works), by embedding it into another event loop |
662 | (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 |
712 | (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 |
663 | also broken on \s-1OS\s0 X)) and, did I mention it, using it only for sockets. |
713 | also broken on \s-1OS X\s0)) and, did I mention it, using it only for sockets. |
664 | .Sp |
714 | .Sp |
665 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR into an \f(CW\*(C`EVFILT_READ\*(C'\fR kevent with |
715 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR into an \f(CW\*(C`EVFILT_READ\*(C'\fR kevent with |
666 | \&\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 |
716 | \&\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 |
667 | \&\f(CW\*(C`NOTE_EOF\*(C'\fR. |
717 | \&\f(CW\*(C`NOTE_EOF\*(C'\fR. |
668 | .ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 |
718 | .ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 |
… | |
… | |
672 | implementation). According to reports, \f(CW\*(C`/dev/poll\*(C'\fR only supports sockets |
722 | implementation). According to reports, \f(CW\*(C`/dev/poll\*(C'\fR only supports sockets |
673 | and is not embeddable, which would limit the usefulness of this backend |
723 | and is not embeddable, which would limit the usefulness of this backend |
674 | immensely. |
724 | immensely. |
675 | .ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 |
725 | .ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 |
676 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
726 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
677 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
727 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
678 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
728 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
679 | it's really slow, but it still scales very well (O(active_fds)). |
729 | it's really slow, but it still scales very well (O(active_fds)). |
680 | .Sp |
|
|
681 | Please note that Solaris event ports can deliver a lot of spurious |
|
|
682 | notifications, so you need to use non-blocking I/O or other means to avoid |
|
|
683 | blocking when no data (or space) is available. |
|
|
684 | .Sp |
730 | .Sp |
685 | While this backend scales well, it requires one system call per active |
731 | While this backend scales well, it requires one system call per active |
686 | file descriptor per loop iteration. For small and medium numbers of file |
732 | file descriptor per loop iteration. For small and medium numbers of file |
687 | descriptors a \*(L"slow\*(R" \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR backend |
733 | descriptors a \*(L"slow\*(R" \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR backend |
688 | might perform better. |
734 | might perform better. |
689 | .Sp |
735 | .Sp |
690 | On the positive side, with the exception of the spurious readiness |
736 | On the positive side, this backend actually performed fully to |
691 | notifications, this backend actually performed fully to specification |
|
|
692 | in all tests and is fully embeddable, which is a rare feat among the |
737 | specification in all tests and is fully embeddable, which is a rare feat |
693 | OS-specific backends (I vastly prefer correctness over speed hacks). |
738 | among the OS-specific backends (I vastly prefer correctness over speed |
|
|
739 | hacks). |
|
|
740 | .Sp |
|
|
741 | On the negative side, the interface is \fIbizarre\fR \- so bizarre that |
|
|
742 | even sun itself gets it wrong in their code examples: The event polling |
|
|
743 | function sometimes returns events to the caller even though an error |
|
|
744 | occurred, but with no indication whether it has done so or not (yes, it's |
|
|
745 | even documented that way) \- deadly for edge-triggered interfaces where you |
|
|
746 | absolutely have to know whether an event occurred or not because you have |
|
|
747 | to re-arm the watcher. |
|
|
748 | .Sp |
|
|
749 | Fortunately libev seems to be able to work around these idiocies. |
694 | .Sp |
750 | .Sp |
695 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
751 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
696 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
752 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
697 | .ie n .IP """EVBACKEND_ALL""" 4 |
753 | .ie n .IP """EVBACKEND_ALL""" 4 |
698 | .el .IP "\f(CWEVBACKEND_ALL\fR" 4 |
754 | .el .IP "\f(CWEVBACKEND_ALL\fR" 4 |
699 | .IX Item "EVBACKEND_ALL" |
755 | .IX Item "EVBACKEND_ALL" |
700 | Try all backends (even potentially broken ones that wouldn't be tried |
756 | Try all backends (even potentially broken ones that wouldn't be tried |
701 | with \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). Since this is a mask, you can do stuff such as |
757 | with \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). Since this is a mask, you can do stuff such as |
702 | \&\f(CW\*(C`EVBACKEND_ALL & ~EVBACKEND_KQUEUE\*(C'\fR. |
758 | \&\f(CW\*(C`EVBACKEND_ALL & ~EVBACKEND_KQUEUE\*(C'\fR. |
703 | .Sp |
759 | .Sp |
704 | It is definitely not recommended to use this flag. |
760 | It is definitely not recommended to use this flag, use whatever |
|
|
761 | \&\f(CW\*(C`ev_recommended_backends ()\*(C'\fR returns, or simply do not specify a backend |
|
|
762 | at all. |
|
|
763 | .ie n .IP """EVBACKEND_MASK""" 4 |
|
|
764 | .el .IP "\f(CWEVBACKEND_MASK\fR" 4 |
|
|
765 | .IX Item "EVBACKEND_MASK" |
|
|
766 | Not a backend at all, but a mask to select all backend bits from a |
|
|
767 | \&\f(CW\*(C`flags\*(C'\fR value, in case you want to mask out any backends from a flags |
|
|
768 | value (e.g. when modifying the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR environment variable). |
705 | .RE |
769 | .RE |
706 | .RS 4 |
770 | .RS 4 |
707 | .Sp |
771 | .Sp |
708 | If one or more of the backend flags are or'ed into the flags value, |
772 | If one or more of the backend flags are or'ed into the flags value, |
709 | then only these backends will be tried (in the reverse order as listed |
773 | then only these backends will be tried (in the reverse order as listed |
… | |
… | |
747 | except in the rare occasion where you really need to free its resources. |
811 | except in the rare occasion where you really need to free its resources. |
748 | If you need dynamically allocated loops it is better to use \f(CW\*(C`ev_loop_new\*(C'\fR |
812 | If you need dynamically allocated loops it is better to use \f(CW\*(C`ev_loop_new\*(C'\fR |
749 | and \f(CW\*(C`ev_loop_destroy\*(C'\fR. |
813 | and \f(CW\*(C`ev_loop_destroy\*(C'\fR. |
750 | .IP "ev_loop_fork (loop)" 4 |
814 | .IP "ev_loop_fork (loop)" 4 |
751 | .IX Item "ev_loop_fork (loop)" |
815 | .IX Item "ev_loop_fork (loop)" |
752 | This function sets a flag that causes subsequent \f(CW\*(C`ev_run\*(C'\fR iterations to |
816 | This function sets a flag that causes subsequent \f(CW\*(C`ev_run\*(C'\fR iterations |
753 | reinitialise the kernel state for backends that have one. Despite the |
817 | to reinitialise the kernel state for backends that have one. Despite |
754 | name, you can call it anytime, but it makes most sense after forking, in |
818 | the name, you can call it anytime you are allowed to start or stop |
755 | the child process. You \fImust\fR call it (or use \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR) in the |
819 | watchers (except inside an \f(CW\*(C`ev_prepare\*(C'\fR callback), but it makes most |
756 | child before resuming or calling \f(CW\*(C`ev_run\*(C'\fR. |
820 | sense after forking, in the child process. You \fImust\fR call it (or use |
|
|
821 | \&\f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR) in the child before resuming or calling \f(CW\*(C`ev_run\*(C'\fR. |
757 | .Sp |
822 | .Sp |
|
|
823 | In addition, if you want to reuse a loop (via this function or |
|
|
824 | \&\f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR), you \fIalso\fR have to ignore \f(CW\*(C`SIGPIPE\*(C'\fR. |
|
|
825 | .Sp |
758 | Again, you \fIhave\fR to call it on \fIany\fR loop that you want to re-use after |
826 | Again, you \fIhave\fR to call it on \fIany\fR loop that you want to re-use after |
759 | a fork, \fIeven if you do not plan to use the loop in the parent\fR. This is |
827 | a fork, \fIeven if you do not plan to use the loop in the parent\fR. This is |
760 | because some kernel interfaces *cough* \fIkqueue\fR *cough* do funny things |
828 | because some kernel interfaces *cough* \fIkqueue\fR *cough* do funny things |
761 | during fork. |
829 | during fork. |
762 | .Sp |
830 | .Sp |
763 | On the other hand, you only need to call this function in the child |
831 | On the other hand, you only need to call this function in the child |
… | |
… | |
798 | \&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls \- and is incremented between the |
866 | \&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls \- and is incremented between the |
799 | prepare and check phases. |
867 | prepare and check phases. |
800 | .IP "unsigned int ev_depth (loop)" 4 |
868 | .IP "unsigned int ev_depth (loop)" 4 |
801 | .IX Item "unsigned int ev_depth (loop)" |
869 | .IX Item "unsigned int ev_depth (loop)" |
802 | Returns the number of times \f(CW\*(C`ev_run\*(C'\fR was entered minus the number of |
870 | Returns the number of times \f(CW\*(C`ev_run\*(C'\fR was entered minus the number of |
803 | times \f(CW\*(C`ev_run\*(C'\fR was exited, in other words, the recursion depth. |
871 | times \f(CW\*(C`ev_run\*(C'\fR was exited normally, in other words, the recursion depth. |
804 | .Sp |
872 | .Sp |
805 | Outside \f(CW\*(C`ev_run\*(C'\fR, this number is zero. In a callback, this number is |
873 | Outside \f(CW\*(C`ev_run\*(C'\fR, this number is zero. In a callback, this number is |
806 | \&\f(CW1\fR, unless \f(CW\*(C`ev_run\*(C'\fR was invoked recursively (or from another thread), |
874 | \&\f(CW1\fR, unless \f(CW\*(C`ev_run\*(C'\fR was invoked recursively (or from another thread), |
807 | in which case it is higher. |
875 | in which case it is higher. |
808 | .Sp |
876 | .Sp |
809 | Leaving \f(CW\*(C`ev_run\*(C'\fR abnormally (setjmp/longjmp, cancelling the thread |
877 | Leaving \f(CW\*(C`ev_run\*(C'\fR abnormally (setjmp/longjmp, cancelling the thread, |
810 | etc.), doesn't count as \*(L"exit\*(R" \- consider this as a hint to avoid such |
878 | throwing an exception etc.), doesn't count as \*(L"exit\*(R" \- consider this |
811 | ungentleman-like behaviour unless it's really convenient. |
879 | as a hint to avoid such ungentleman-like behaviour unless it's really |
|
|
880 | convenient, in which case it is fully supported. |
812 | .IP "unsigned int ev_backend (loop)" 4 |
881 | .IP "unsigned int ev_backend (loop)" 4 |
813 | .IX Item "unsigned int ev_backend (loop)" |
882 | .IX Item "unsigned int ev_backend (loop)" |
814 | Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in |
883 | Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in |
815 | use. |
884 | use. |
816 | .IP "ev_tstamp ev_now (loop)" 4 |
885 | .IP "ev_tstamp ev_now (loop)" 4 |
… | |
… | |
856 | given loop other than \f(CW\*(C`ev_resume\*(C'\fR, and you \fBmust not\fR call \f(CW\*(C`ev_resume\*(C'\fR |
925 | given loop other than \f(CW\*(C`ev_resume\*(C'\fR, and you \fBmust not\fR call \f(CW\*(C`ev_resume\*(C'\fR |
857 | without a previous call to \f(CW\*(C`ev_suspend\*(C'\fR. |
926 | without a previous call to \f(CW\*(C`ev_suspend\*(C'\fR. |
858 | .Sp |
927 | .Sp |
859 | Calling \f(CW\*(C`ev_suspend\*(C'\fR/\f(CW\*(C`ev_resume\*(C'\fR has the side effect of updating the |
928 | Calling \f(CW\*(C`ev_suspend\*(C'\fR/\f(CW\*(C`ev_resume\*(C'\fR has the side effect of updating the |
860 | event loop time (see \f(CW\*(C`ev_now_update\*(C'\fR). |
929 | event loop time (see \f(CW\*(C`ev_now_update\*(C'\fR). |
861 | .IP "ev_run (loop, int flags)" 4 |
930 | .IP "bool ev_run (loop, int flags)" 4 |
862 | .IX Item "ev_run (loop, int flags)" |
931 | .IX Item "bool ev_run (loop, int flags)" |
863 | Finally, this is it, the event handler. This function usually is called |
932 | Finally, this is it, the event handler. This function usually is called |
864 | after you have initialised all your watchers and you want to start |
933 | after you have initialised all your watchers and you want to start |
865 | handling events. It will ask the operating system for any new events, call |
934 | handling events. It will ask the operating system for any new events, call |
866 | the watcher callbacks, an then repeat the whole process indefinitely: This |
935 | the watcher callbacks, and then repeat the whole process indefinitely: This |
867 | is why event loops are called \fIloops\fR. |
936 | is why event loops are called \fIloops\fR. |
868 | .Sp |
937 | .Sp |
869 | If the flags argument is specified as \f(CW0\fR, it will keep handling events |
938 | If the flags argument is specified as \f(CW0\fR, it will keep handling events |
870 | until either no event watchers are active anymore or \f(CW\*(C`ev_break\*(C'\fR was |
939 | until either no event watchers are active anymore or \f(CW\*(C`ev_break\*(C'\fR was |
871 | called. |
940 | called. |
|
|
941 | .Sp |
|
|
942 | The return value is false if there are no more active watchers (which |
|
|
943 | usually means \*(L"all jobs done\*(R" or \*(L"deadlock\*(R"), and true in all other cases |
|
|
944 | (which usually means " you should call \f(CW\*(C`ev_run\*(C'\fR again"). |
872 | .Sp |
945 | .Sp |
873 | Please note that an explicit \f(CW\*(C`ev_break\*(C'\fR is usually better than |
946 | Please note that an explicit \f(CW\*(C`ev_break\*(C'\fR is usually better than |
874 | relying on all watchers to be stopped when deciding when a program has |
947 | relying on all watchers to be stopped when deciding when a program has |
875 | finished (especially in interactive programs), but having a program |
948 | finished (especially in interactive programs), but having a program |
876 | that automatically loops as long as it has to and no longer by virtue |
949 | that automatically loops as long as it has to and no longer by virtue |
877 | of relying on its watchers stopping correctly, that is truly a thing of |
950 | of relying on its watchers stopping correctly, that is truly a thing of |
878 | beauty. |
951 | beauty. |
879 | .Sp |
952 | .Sp |
|
|
953 | This function is \fImostly\fR exception-safe \- you can break out of a |
|
|
954 | \&\f(CW\*(C`ev_run\*(C'\fR call by calling \f(CW\*(C`longjmp\*(C'\fR in a callback, throwing a \*(C+ |
|
|
955 | exception and so on. This does not decrement the \f(CW\*(C`ev_depth\*(C'\fR value, nor |
|
|
956 | will it clear any outstanding \f(CW\*(C`EVBREAK_ONE\*(C'\fR breaks. |
|
|
957 | .Sp |
880 | A flags value of \f(CW\*(C`EVRUN_NOWAIT\*(C'\fR will look for new events, will handle |
958 | A flags value of \f(CW\*(C`EVRUN_NOWAIT\*(C'\fR will look for new events, will handle |
881 | those events and any already outstanding ones, but will not wait and |
959 | those events and any already outstanding ones, but will not wait and |
882 | block your process in case there are no events and will return after one |
960 | block your process in case there are no events and will return after one |
883 | iteration of the loop. This is sometimes useful to poll and handle new |
961 | iteration of the loop. This is sometimes useful to poll and handle new |
884 | events while doing lengthy calculations, to keep the program responsive. |
962 | events while doing lengthy calculations, to keep the program responsive. |
… | |
… | |
893 | This is useful if you are waiting for some external event in conjunction |
971 | This is useful if you are waiting for some external event in conjunction |
894 | with something not expressible using other libev watchers (i.e. "roll your |
972 | with something not expressible using other libev watchers (i.e. "roll your |
895 | 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 |
973 | 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 |
896 | usually a better approach for this kind of thing. |
974 | usually a better approach for this kind of thing. |
897 | .Sp |
975 | .Sp |
898 | Here are the gory details of what \f(CW\*(C`ev_run\*(C'\fR does: |
976 | Here are the gory details of what \f(CW\*(C`ev_run\*(C'\fR does (this is for your |
|
|
977 | understanding, not a guarantee that things will work exactly like this in |
|
|
978 | future versions): |
899 | .Sp |
979 | .Sp |
900 | .Vb 10 |
980 | .Vb 10 |
901 | \& \- Increment loop depth. |
981 | \& \- Increment loop depth. |
902 | \& \- Reset the ev_break status. |
982 | \& \- Reset the ev_break status. |
903 | \& \- Before the first iteration, call any pending watchers. |
983 | \& \- Before the first iteration, call any pending watchers. |
… | |
… | |
939 | .Sp |
1019 | .Sp |
940 | .Vb 4 |
1020 | .Vb 4 |
941 | \& ... queue jobs here, make sure they register event watchers as long |
1021 | \& ... queue jobs here, make sure they register event watchers as long |
942 | \& ... as they still have work to do (even an idle watcher will do..) |
1022 | \& ... as they still have work to do (even an idle watcher will do..) |
943 | \& ev_run (my_loop, 0); |
1023 | \& ev_run (my_loop, 0); |
944 | \& ... jobs done or somebody called unloop. yeah! |
1024 | \& ... jobs done or somebody called break. yeah! |
945 | .Ve |
1025 | .Ve |
946 | .IP "ev_break (loop, how)" 4 |
1026 | .IP "ev_break (loop, how)" 4 |
947 | .IX Item "ev_break (loop, how)" |
1027 | .IX Item "ev_break (loop, how)" |
948 | Can be used to make a call to \f(CW\*(C`ev_run\*(C'\fR return early (but only after it |
1028 | Can be used to make a call to \f(CW\*(C`ev_run\*(C'\fR return early (but only after it |
949 | has processed all outstanding events). The \f(CW\*(C`how\*(C'\fR argument must be either |
1029 | has processed all outstanding events). The \f(CW\*(C`how\*(C'\fR argument must be either |
950 | \&\f(CW\*(C`EVBREAK_ONE\*(C'\fR, which will make the innermost \f(CW\*(C`ev_run\*(C'\fR call return, or |
1030 | \&\f(CW\*(C`EVBREAK_ONE\*(C'\fR, which will make the innermost \f(CW\*(C`ev_run\*(C'\fR call return, or |
951 | \&\f(CW\*(C`EVBREAK_ALL\*(C'\fR, which will make all nested \f(CW\*(C`ev_run\*(C'\fR calls return. |
1031 | \&\f(CW\*(C`EVBREAK_ALL\*(C'\fR, which will make all nested \f(CW\*(C`ev_run\*(C'\fR calls return. |
952 | .Sp |
1032 | .Sp |
953 | This \*(L"break state\*(R" will be cleared when entering \f(CW\*(C`ev_run\*(C'\fR again. |
1033 | This \*(L"break state\*(R" will be cleared on the next call to \f(CW\*(C`ev_run\*(C'\fR. |
954 | .Sp |
1034 | .Sp |
955 | It is safe to call \f(CW\*(C`ev_break\*(C'\fR from outside any \f(CW\*(C`ev_run\*(C'\fR calls, too. |
1035 | It is safe to call \f(CW\*(C`ev_break\*(C'\fR from outside any \f(CW\*(C`ev_run\*(C'\fR calls, too, in |
|
|
1036 | which case it will have no effect. |
956 | .IP "ev_ref (loop)" 4 |
1037 | .IP "ev_ref (loop)" 4 |
957 | .IX Item "ev_ref (loop)" |
1038 | .IX Item "ev_ref (loop)" |
958 | .PD 0 |
1039 | .PD 0 |
959 | .IP "ev_unref (loop)" 4 |
1040 | .IP "ev_unref (loop)" 4 |
960 | .IX Item "ev_unref (loop)" |
1041 | .IX Item "ev_unref (loop)" |
… | |
… | |
983 | .Sp |
1064 | .Sp |
984 | .Vb 4 |
1065 | .Vb 4 |
985 | \& ev_signal exitsig; |
1066 | \& ev_signal exitsig; |
986 | \& ev_signal_init (&exitsig, sig_cb, SIGINT); |
1067 | \& ev_signal_init (&exitsig, sig_cb, SIGINT); |
987 | \& ev_signal_start (loop, &exitsig); |
1068 | \& ev_signal_start (loop, &exitsig); |
988 | \& evf_unref (loop); |
1069 | \& ev_unref (loop); |
989 | .Ve |
1070 | .Ve |
990 | .Sp |
1071 | .Sp |
991 | Example: For some weird reason, unregister the above signal handler again. |
1072 | Example: For some weird reason, unregister the above signal handler again. |
992 | .Sp |
1073 | .Sp |
993 | .Vb 2 |
1074 | .Vb 2 |
… | |
… | |
1017 | overhead for the actual polling but can deliver many events at once. |
1098 | overhead for the actual polling but can deliver many events at once. |
1018 | .Sp |
1099 | .Sp |
1019 | By setting a higher \fIio collect interval\fR you allow libev to spend more |
1100 | By setting a higher \fIio collect interval\fR you allow libev to spend more |
1020 | time collecting I/O events, so you can handle more events per iteration, |
1101 | time collecting I/O events, so you can handle more events per iteration, |
1021 | at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and |
1102 | at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and |
1022 | \&\f(CW\*(C`ev_timer\*(C'\fR) will be not affected. Setting this to a non-null value will |
1103 | \&\f(CW\*(C`ev_timer\*(C'\fR) will not be affected. Setting this to a non-null value will |
1023 | introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations. The |
1104 | introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations. The |
1024 | sleep time ensures that libev will not poll for I/O events more often then |
1105 | sleep time ensures that libev will not poll for I/O events more often then |
1025 | once per this interval, on average. |
1106 | once per this interval, on average (as long as the host time resolution is |
|
|
1107 | good enough). |
1026 | .Sp |
1108 | .Sp |
1027 | Likewise, by setting a higher \fItimeout collect interval\fR you allow libev |
1109 | Likewise, by setting a higher \fItimeout collect interval\fR you allow libev |
1028 | to spend more time collecting timeouts, at the expense of increased |
1110 | to spend more time collecting timeouts, at the expense of increased |
1029 | latency/jitter/inexactness (the watcher callback will be called |
1111 | latency/jitter/inexactness (the watcher callback will be called |
1030 | later). \f(CW\*(C`ev_io\*(C'\fR watchers will not be affected. Setting this to a non-null |
1112 | later). \f(CW\*(C`ev_io\*(C'\fR watchers will not be affected. Setting this to a non-null |
… | |
… | |
1074 | this callback instead. This is useful, for example, when you want to |
1156 | this callback instead. This is useful, for example, when you want to |
1075 | invoke the actual watchers inside another context (another thread etc.). |
1157 | invoke the actual watchers inside another context (another thread etc.). |
1076 | .Sp |
1158 | .Sp |
1077 | If you want to reset the callback, use \f(CW\*(C`ev_invoke_pending\*(C'\fR as new |
1159 | If you want to reset the callback, use \f(CW\*(C`ev_invoke_pending\*(C'\fR as new |
1078 | callback. |
1160 | callback. |
1079 | .IP "ev_set_loop_release_cb (loop, void (*release)(\s-1EV_P\s0), void (*acquire)(\s-1EV_P\s0))" 4 |
1161 | .IP "ev_set_loop_release_cb (loop, void (*release)(\s-1EV_P\s0) throw (), void (*acquire)(\s-1EV_P\s0) throw ())" 4 |
1080 | .IX Item "ev_set_loop_release_cb (loop, void (*release)(EV_P), void (*acquire)(EV_P))" |
1162 | .IX Item "ev_set_loop_release_cb (loop, void (*release)(EV_P) throw (), void (*acquire)(EV_P) throw ())" |
1081 | Sometimes you want to share the same loop between multiple threads. This |
1163 | Sometimes you want to share the same loop between multiple threads. This |
1082 | can be done relatively simply by putting mutex_lock/unlock calls around |
1164 | can be done relatively simply by putting mutex_lock/unlock calls around |
1083 | each call to a libev function. |
1165 | each call to a libev function. |
1084 | .Sp |
1166 | .Sp |
1085 | However, \f(CW\*(C`ev_run\*(C'\fR can run an indefinite time, so it is not feasible |
1167 | However, \f(CW\*(C`ev_run\*(C'\fR can run an indefinite time, so it is not feasible |
1086 | to wait for it to return. One way around this is to wake up the event |
1168 | to wait for it to return. One way around this is to wake up the event |
1087 | loop via \f(CW\*(C`ev_break\*(C'\fR and \f(CW\*(C`av_async_send\*(C'\fR, another way is to set these |
1169 | loop via \f(CW\*(C`ev_break\*(C'\fR and \f(CW\*(C`ev_async_send\*(C'\fR, another way is to set these |
1088 | \&\fIrelease\fR and \fIacquire\fR callbacks on the loop. |
1170 | \&\fIrelease\fR and \fIacquire\fR callbacks on the loop. |
1089 | .Sp |
1171 | .Sp |
1090 | When set, then \f(CW\*(C`release\*(C'\fR will be called just before the thread is |
1172 | When set, then \f(CW\*(C`release\*(C'\fR will be called just before the thread is |
1091 | suspended waiting for new events, and \f(CW\*(C`acquire\*(C'\fR is called just |
1173 | suspended waiting for new events, and \f(CW\*(C`acquire\*(C'\fR is called just |
1092 | afterwards. |
1174 | afterwards. |
… | |
… | |
1107 | See also the locking example in the \f(CW\*(C`THREADS\*(C'\fR section later in this |
1189 | See also the locking example in the \f(CW\*(C`THREADS\*(C'\fR section later in this |
1108 | document. |
1190 | document. |
1109 | .IP "ev_set_userdata (loop, void *data)" 4 |
1191 | .IP "ev_set_userdata (loop, void *data)" 4 |
1110 | .IX Item "ev_set_userdata (loop, void *data)" |
1192 | .IX Item "ev_set_userdata (loop, void *data)" |
1111 | .PD 0 |
1193 | .PD 0 |
1112 | .IP "ev_userdata (loop)" 4 |
1194 | .IP "void *ev_userdata (loop)" 4 |
1113 | .IX Item "ev_userdata (loop)" |
1195 | .IX Item "void *ev_userdata (loop)" |
1114 | .PD |
1196 | .PD |
1115 | Set and retrieve a single \f(CW\*(C`void *\*(C'\fR associated with a loop. When |
1197 | Set and retrieve a single \f(CW\*(C`void *\*(C'\fR associated with a loop. When |
1116 | \&\f(CW\*(C`ev_set_userdata\*(C'\fR has never been called, then \f(CW\*(C`ev_userdata\*(C'\fR returns |
1198 | \&\f(CW\*(C`ev_set_userdata\*(C'\fR has never been called, then \f(CW\*(C`ev_userdata\*(C'\fR returns |
1117 | \&\f(CW0.\fR |
1199 | \&\f(CW0\fR. |
1118 | .Sp |
1200 | .Sp |
1119 | These two functions can be used to associate arbitrary data with a loop, |
1201 | These two functions can be used to associate arbitrary data with a loop, |
1120 | and are intended solely for the \f(CW\*(C`invoke_pending_cb\*(C'\fR, \f(CW\*(C`release\*(C'\fR and |
1202 | and are intended solely for the \f(CW\*(C`invoke_pending_cb\*(C'\fR, \f(CW\*(C`release\*(C'\fR and |
1121 | \&\f(CW\*(C`acquire\*(C'\fR callbacks described above, but of course can be (ab\-)used for |
1203 | \&\f(CW\*(C`acquire\*(C'\fR callbacks described above, but of course can be (ab\-)used for |
1122 | any other purpose as well. |
1204 | any other purpose as well. |
… | |
… | |
1233 | .PD 0 |
1315 | .PD 0 |
1234 | .ie n .IP """EV_CHECK""" 4 |
1316 | .ie n .IP """EV_CHECK""" 4 |
1235 | .el .IP "\f(CWEV_CHECK\fR" 4 |
1317 | .el .IP "\f(CWEV_CHECK\fR" 4 |
1236 | .IX Item "EV_CHECK" |
1318 | .IX Item "EV_CHECK" |
1237 | .PD |
1319 | .PD |
1238 | All \f(CW\*(C`ev_prepare\*(C'\fR watchers are invoked just \fIbefore\fR \f(CW\*(C`ev_run\*(C'\fR starts |
1320 | All \f(CW\*(C`ev_prepare\*(C'\fR watchers are invoked just \fIbefore\fR \f(CW\*(C`ev_run\*(C'\fR starts to |
1239 | to gather new events, and all \f(CW\*(C`ev_check\*(C'\fR watchers are invoked just after |
1321 | gather new events, and all \f(CW\*(C`ev_check\*(C'\fR watchers are queued (not invoked) |
1240 | \&\f(CW\*(C`ev_run\*(C'\fR has gathered them, but before it invokes any callbacks for any |
1322 | just after \f(CW\*(C`ev_run\*(C'\fR has gathered them, but before it queues any callbacks |
|
|
1323 | for any received events. That means \f(CW\*(C`ev_prepare\*(C'\fR watchers are the last |
|
|
1324 | watchers invoked before the event loop sleeps or polls for new events, and |
|
|
1325 | \&\f(CW\*(C`ev_check\*(C'\fR watchers will be invoked before any other watchers of the same |
|
|
1326 | or lower priority within an event loop iteration. |
|
|
1327 | .Sp |
1241 | received events. Callbacks of both watcher types can start and stop as |
1328 | Callbacks of both watcher types can start and stop as many watchers as |
1242 | many watchers as they want, and all of them will be taken into account |
1329 | they want, and all of them will be taken into account (for example, a |
1243 | (for example, a \f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep |
1330 | \&\f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep \f(CW\*(C`ev_run\*(C'\fR from |
1244 | \&\f(CW\*(C`ev_run\*(C'\fR from blocking). |
1331 | blocking). |
1245 | .ie n .IP """EV_EMBED""" 4 |
1332 | .ie n .IP """EV_EMBED""" 4 |
1246 | .el .IP "\f(CWEV_EMBED\fR" 4 |
1333 | .el .IP "\f(CWEV_EMBED\fR" 4 |
1247 | .IX Item "EV_EMBED" |
1334 | .IX Item "EV_EMBED" |
1248 | The embedded event loop specified in the \f(CW\*(C`ev_embed\*(C'\fR watcher needs attention. |
1335 | The embedded event loop specified in the \f(CW\*(C`ev_embed\*(C'\fR watcher needs attention. |
1249 | .ie n .IP """EV_FORK""" 4 |
1336 | .ie n .IP """EV_FORK""" 4 |
… | |
… | |
1281 | example it might indicate that a fd is readable or writable, and if your |
1368 | example it might indicate that a fd is readable or writable, and if your |
1282 | callbacks is well-written it can just attempt the operation and cope with |
1369 | callbacks is well-written it can just attempt the operation and cope with |
1283 | the error from \fIread()\fR or \fIwrite()\fR. This will not work in multi-threaded |
1370 | the error from \fIread()\fR or \fIwrite()\fR. This will not work in multi-threaded |
1284 | programs, though, as the fd could already be closed and reused for another |
1371 | programs, though, as the fd could already be closed and reused for another |
1285 | thing, so beware. |
1372 | thing, so beware. |
1286 | .SS "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0" |
1373 | .SS "\s-1GENERIC WATCHER FUNCTIONS\s0" |
1287 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
1374 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
1288 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
1375 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
1289 | .el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 |
1376 | .el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 |
1290 | .IX Item "ev_init (ev_TYPE *watcher, callback)" |
1377 | .IX Item "ev_init (ev_TYPE *watcher, callback)" |
1291 | This macro initialises the generic portion of a watcher. The contents |
1378 | This macro initialises the generic portion of a watcher. The contents |
… | |
… | |
1370 | make sure the watcher is available to libev (e.g. you cannot \f(CW\*(C`free ()\*(C'\fR |
1457 | make sure the watcher is available to libev (e.g. you cannot \f(CW\*(C`free ()\*(C'\fR |
1371 | it). |
1458 | it). |
1372 | .IP "callback ev_cb (ev_TYPE *watcher)" 4 |
1459 | .IP "callback ev_cb (ev_TYPE *watcher)" 4 |
1373 | .IX Item "callback ev_cb (ev_TYPE *watcher)" |
1460 | .IX Item "callback ev_cb (ev_TYPE *watcher)" |
1374 | Returns the callback currently set on the watcher. |
1461 | Returns the callback currently set on the watcher. |
1375 | .IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 |
1462 | .IP "ev_set_cb (ev_TYPE *watcher, callback)" 4 |
1376 | .IX Item "ev_cb_set (ev_TYPE *watcher, callback)" |
1463 | .IX Item "ev_set_cb (ev_TYPE *watcher, callback)" |
1377 | Change the callback. You can change the callback at virtually any time |
1464 | Change the callback. You can change the callback at virtually any time |
1378 | (modulo threads). |
1465 | (modulo threads). |
1379 | .IP "ev_set_priority (ev_TYPE *watcher, int priority)" 4 |
1466 | .IP "ev_set_priority (ev_TYPE *watcher, int priority)" 4 |
1380 | .IX Item "ev_set_priority (ev_TYPE *watcher, int priority)" |
1467 | .IX Item "ev_set_priority (ev_TYPE *watcher, int priority)" |
1381 | .PD 0 |
1468 | .PD 0 |
… | |
… | |
1399 | or might not have been clamped to the valid range. |
1486 | or might not have been clamped to the valid range. |
1400 | .Sp |
1487 | .Sp |
1401 | The default priority used by watchers when no priority has been set is |
1488 | The default priority used by watchers when no priority has been set is |
1402 | always \f(CW0\fR, which is supposed to not be too high and not be too low :). |
1489 | always \f(CW0\fR, which is supposed to not be too high and not be too low :). |
1403 | .Sp |
1490 | .Sp |
1404 | See \*(L"\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0\*(R", below, for a more thorough treatment of |
1491 | See \*(L"\s-1WATCHER PRIORITY MODELS\*(R"\s0, below, for a more thorough treatment of |
1405 | priorities. |
1492 | priorities. |
1406 | .IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4 |
1493 | .IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4 |
1407 | .IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)" |
1494 | .IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)" |
1408 | 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 |
1495 | 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 |
1409 | \&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback |
1496 | \&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback |
… | |
… | |
1428 | \&\f(CW\*(C`ev_clear_pending\*(C'\fR will clear the pending event, even if the watcher was |
1515 | \&\f(CW\*(C`ev_clear_pending\*(C'\fR will clear the pending event, even if the watcher was |
1429 | not started in the first place. |
1516 | not started in the first place. |
1430 | .Sp |
1517 | .Sp |
1431 | See also \f(CW\*(C`ev_feed_fd_event\*(C'\fR and \f(CW\*(C`ev_feed_signal_event\*(C'\fR for related |
1518 | See also \f(CW\*(C`ev_feed_fd_event\*(C'\fR and \f(CW\*(C`ev_feed_signal_event\*(C'\fR for related |
1432 | functions that do not need a watcher. |
1519 | functions that do not need a watcher. |
1433 | .SS "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" |
|
|
1434 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
|
|
1435 | Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change |
|
|
1436 | and read at any time: libev will completely ignore it. This can be used |
|
|
1437 | to associate arbitrary data with your watcher. If you need more data and |
|
|
1438 | don't want to allocate memory and store a pointer to it in that data |
|
|
1439 | member, you can also \*(L"subclass\*(R" the watcher type and provide your own |
|
|
1440 | data: |
|
|
1441 | .PP |
1520 | .PP |
1442 | .Vb 7 |
1521 | See also the \*(L"\s-1ASSOCIATING CUSTOM DATA WITH A WATCHER\*(R"\s0 and \*(L"\s-1BUILDING YOUR |
1443 | \& struct my_io |
1522 | OWN COMPOSITE WATCHERS\*(R"\s0 idioms. |
1444 | \& { |
|
|
1445 | \& ev_io io; |
|
|
1446 | \& int otherfd; |
|
|
1447 | \& void *somedata; |
|
|
1448 | \& struct whatever *mostinteresting; |
|
|
1449 | \& }; |
|
|
1450 | \& |
|
|
1451 | \& ... |
|
|
1452 | \& struct my_io w; |
|
|
1453 | \& ev_io_init (&w.io, my_cb, fd, EV_READ); |
|
|
1454 | .Ve |
|
|
1455 | .PP |
|
|
1456 | And since your callback will be called with a pointer to the watcher, you |
|
|
1457 | can cast it back to your own type: |
|
|
1458 | .PP |
|
|
1459 | .Vb 5 |
|
|
1460 | \& static void my_cb (struct ev_loop *loop, ev_io *w_, int revents) |
|
|
1461 | \& { |
|
|
1462 | \& struct my_io *w = (struct my_io *)w_; |
|
|
1463 | \& ... |
|
|
1464 | \& } |
|
|
1465 | .Ve |
|
|
1466 | .PP |
|
|
1467 | More interesting and less C\-conformant ways of casting your callback type |
|
|
1468 | instead have been omitted. |
|
|
1469 | .PP |
|
|
1470 | Another common scenario is to use some data structure with multiple |
|
|
1471 | embedded watchers: |
|
|
1472 | .PP |
|
|
1473 | .Vb 6 |
|
|
1474 | \& struct my_biggy |
|
|
1475 | \& { |
|
|
1476 | \& int some_data; |
|
|
1477 | \& ev_timer t1; |
|
|
1478 | \& ev_timer t2; |
|
|
1479 | \& } |
|
|
1480 | .Ve |
|
|
1481 | .PP |
|
|
1482 | In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more |
|
|
1483 | complicated: Either you store the address of your \f(CW\*(C`my_biggy\*(C'\fR struct |
|
|
1484 | in the \f(CW\*(C`data\*(C'\fR member of the watcher (for woozies), or you need to use |
|
|
1485 | some pointer arithmetic using \f(CW\*(C`offsetof\*(C'\fR inside your watchers (for real |
|
|
1486 | programmers): |
|
|
1487 | .PP |
|
|
1488 | .Vb 1 |
|
|
1489 | \& #include <stddef.h> |
|
|
1490 | \& |
|
|
1491 | \& static void |
|
|
1492 | \& t1_cb (EV_P_ ev_timer *w, int revents) |
|
|
1493 | \& { |
|
|
1494 | \& struct my_biggy big = (struct my_biggy *) |
|
|
1495 | \& (((char *)w) \- offsetof (struct my_biggy, t1)); |
|
|
1496 | \& } |
|
|
1497 | \& |
|
|
1498 | \& static void |
|
|
1499 | \& t2_cb (EV_P_ ev_timer *w, int revents) |
|
|
1500 | \& { |
|
|
1501 | \& struct my_biggy big = (struct my_biggy *) |
|
|
1502 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
|
|
1503 | \& } |
|
|
1504 | .Ve |
|
|
1505 | .SS "\s-1WATCHER\s0 \s-1STATES\s0" |
1523 | .SS "\s-1WATCHER STATES\s0" |
1506 | .IX Subsection "WATCHER STATES" |
1524 | .IX Subsection "WATCHER STATES" |
1507 | There are various watcher states mentioned throughout this manual \- |
1525 | There are various watcher states mentioned throughout this manual \- |
1508 | active, pending and so on. In this section these states and the rules to |
1526 | active, pending and so on. In this section these states and the rules to |
1509 | transition between them will be described in more detail \- and while these |
1527 | transition between them will be described in more detail \- and while these |
1510 | rules might look complicated, they usually do \*(L"the right thing\*(R". |
1528 | rules might look complicated, they usually do \*(L"the right thing\*(R". |
1511 | .IP "initialiased" 4 |
1529 | .IP "initialised" 4 |
1512 | .IX Item "initialiased" |
1530 | .IX Item "initialised" |
1513 | Before a watcher can be registered with the event looop it has to be |
1531 | Before a watcher can be registered with the event loop it has to be |
1514 | initialised. This can be done with a call to \f(CW\*(C`ev_TYPE_init\*(C'\fR, or calls to |
1532 | initialised. This can be done with a call to \f(CW\*(C`ev_TYPE_init\*(C'\fR, or calls to |
1515 | \&\f(CW\*(C`ev_init\*(C'\fR followed by the watcher-specific \f(CW\*(C`ev_TYPE_set\*(C'\fR function. |
1533 | \&\f(CW\*(C`ev_init\*(C'\fR followed by the watcher-specific \f(CW\*(C`ev_TYPE_set\*(C'\fR function. |
1516 | .Sp |
1534 | .Sp |
1517 | In this state it is simply some block of memory that is suitable for use |
1535 | In this state it is simply some block of memory that is suitable for |
1518 | in an event loop. It can be moved around, freed, reused etc. at will. |
1536 | use in an event loop. It can be moved around, freed, reused etc. at |
|
|
1537 | will \- as long as you either keep the memory contents intact, or call |
|
|
1538 | \&\f(CW\*(C`ev_TYPE_init\*(C'\fR again. |
1519 | .IP "started/running/active" 4 |
1539 | .IP "started/running/active" 4 |
1520 | .IX Item "started/running/active" |
1540 | .IX Item "started/running/active" |
1521 | Once a watcher has been started with a call to \f(CW\*(C`ev_TYPE_start\*(C'\fR it becomes |
1541 | Once a watcher has been started with a call to \f(CW\*(C`ev_TYPE_start\*(C'\fR it becomes |
1522 | property of the event loop, and is actively waiting for events. While in |
1542 | property of the event loop, and is actively waiting for events. While in |
1523 | this state it cannot be accessed (except in a few documented ways), moved, |
1543 | this state it cannot be accessed (except in a few documented ways), moved, |
… | |
… | |
1548 | latter will clear any pending state the watcher might be in, regardless |
1568 | latter will clear any pending state the watcher might be in, regardless |
1549 | of whether it was active or not, so stopping a watcher explicitly before |
1569 | of whether it was active or not, so stopping a watcher explicitly before |
1550 | freeing it is often a good idea. |
1570 | freeing it is often a good idea. |
1551 | .Sp |
1571 | .Sp |
1552 | While stopped (and not pending) the watcher is essentially in the |
1572 | While stopped (and not pending) the watcher is essentially in the |
1553 | initialised state, that is it can be reused, moved, modified in any way |
1573 | initialised state, that is, it can be reused, moved, modified in any way |
1554 | you wish. |
1574 | you wish (but when you trash the memory block, you need to \f(CW\*(C`ev_TYPE_init\*(C'\fR |
|
|
1575 | it again). |
1555 | .SS "\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0" |
1576 | .SS "\s-1WATCHER PRIORITY MODELS\s0" |
1556 | .IX Subsection "WATCHER PRIORITY MODELS" |
1577 | .IX Subsection "WATCHER PRIORITY MODELS" |
1557 | Many event loops support \fIwatcher priorities\fR, which are usually small |
1578 | Many event loops support \fIwatcher priorities\fR, which are usually small |
1558 | integers that influence the ordering of event callback invocation |
1579 | integers that influence the ordering of event callback invocation |
1559 | between watchers in some way, all else being equal. |
1580 | between watchers in some way, all else being equal. |
1560 | .PP |
1581 | .PP |
… | |
… | |
1684 | In general you can register as many read and/or write event watchers per |
1705 | In general you can register as many read and/or write event watchers per |
1685 | fd as you want (as long as you don't confuse yourself). Setting all file |
1706 | fd as you want (as long as you don't confuse yourself). Setting all file |
1686 | descriptors to non-blocking mode is also usually a good idea (but not |
1707 | descriptors to non-blocking mode is also usually a good idea (but not |
1687 | required if you know what you are doing). |
1708 | required if you know what you are doing). |
1688 | .PP |
1709 | .PP |
1689 | If you cannot use non-blocking mode, then force the use of a |
|
|
1690 | known-to-be-good backend (at the time of this writing, this includes only |
|
|
1691 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and \f(CW\*(C`EVBACKEND_POLL\*(C'\fR). The same applies to file |
|
|
1692 | descriptors for which non-blocking operation makes no sense (such as |
|
|
1693 | files) \- libev doesn't guarantee any specific behaviour in that case. |
|
|
1694 | .PP |
|
|
1695 | Another thing you have to watch out for is that it is quite easy to |
1710 | Another thing you have to watch out for is that it is quite easy to |
1696 | receive \*(L"spurious\*(R" readiness notifications, that is your callback might |
1711 | receive \*(L"spurious\*(R" readiness notifications, that is, your callback might |
1697 | be called with \f(CW\*(C`EV_READ\*(C'\fR but a subsequent \f(CW\*(C`read\*(C'\fR(2) will actually block |
1712 | be called with \f(CW\*(C`EV_READ\*(C'\fR but a subsequent \f(CW\*(C`read\*(C'\fR(2) will actually block |
1698 | because there is no data. Not only are some backends known to create a |
1713 | because there is no data. It is very easy to get into this situation even |
1699 | lot of those (for example Solaris ports), it is very easy to get into |
1714 | with a relatively standard program structure. Thus it is best to always |
1700 | this situation even with a relatively standard program structure. Thus |
1715 | use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning \f(CW\*(C`EAGAIN\*(C'\fR is far |
1701 | it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning |
|
|
1702 | \&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives. |
1716 | preferable to a program hanging until some data arrives. |
1703 | .PP |
1717 | .PP |
1704 | If you cannot run the fd in non-blocking mode (for example you should |
1718 | If you cannot run the fd in non-blocking mode (for example you should |
1705 | not play around with an Xlib connection), then you have to separately |
1719 | not play around with an Xlib connection), then you have to separately |
1706 | re-test whether a file descriptor is really ready with a known-to-be good |
1720 | re-test whether a file descriptor is really ready with a known-to-be good |
1707 | interface such as poll (fortunately in our Xlib example, Xlib already |
1721 | interface such as poll (fortunately in the case of Xlib, it already does |
1708 | does this on its own, so its quite safe to use). Some people additionally |
1722 | this on its own, so its quite safe to use). Some people additionally |
1709 | use \f(CW\*(C`SIGALRM\*(C'\fR and an interval timer, just to be sure you won't block |
1723 | use \f(CW\*(C`SIGALRM\*(C'\fR and an interval timer, just to be sure you won't block |
1710 | indefinitely. |
1724 | indefinitely. |
1711 | .PP |
1725 | .PP |
1712 | But really, best use non-blocking mode. |
1726 | But really, best use non-blocking mode. |
1713 | .PP |
1727 | .PP |
… | |
… | |
1743 | .PP |
1757 | .PP |
1744 | There is no workaround possible except not registering events |
1758 | There is no workaround possible except not registering events |
1745 | for potentially \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors, or to resort to |
1759 | for potentially \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors, or to resort to |
1746 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
1760 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
1747 | .PP |
1761 | .PP |
|
|
1762 | \fIThe special problem of files\fR |
|
|
1763 | .IX Subsection "The special problem of files" |
|
|
1764 | .PP |
|
|
1765 | Many people try to use \f(CW\*(C`select\*(C'\fR (or libev) on file descriptors |
|
|
1766 | representing files, and expect it to become ready when their program |
|
|
1767 | doesn't block on disk accesses (which can take a long time on their own). |
|
|
1768 | .PP |
|
|
1769 | However, this cannot ever work in the \*(L"expected\*(R" way \- you get a readiness |
|
|
1770 | notification as soon as the kernel knows whether and how much data is |
|
|
1771 | there, and in the case of open files, that's always the case, so you |
|
|
1772 | always get a readiness notification instantly, and your read (or possibly |
|
|
1773 | write) will still block on the disk I/O. |
|
|
1774 | .PP |
|
|
1775 | Another way to view it is that in the case of sockets, pipes, character |
|
|
1776 | devices and so on, there is another party (the sender) that delivers data |
|
|
1777 | on its own, but in the case of files, there is no such thing: the disk |
|
|
1778 | will not send data on its own, simply because it doesn't know what you |
|
|
1779 | wish to read \- you would first have to request some data. |
|
|
1780 | .PP |
|
|
1781 | Since files are typically not-so-well supported by advanced notification |
|
|
1782 | mechanism, libev tries hard to emulate \s-1POSIX\s0 behaviour with respect |
|
|
1783 | to files, even though you should not use it. The reason for this is |
|
|
1784 | convenience: sometimes you want to watch \s-1STDIN\s0 or \s-1STDOUT,\s0 which is |
|
|
1785 | usually a tty, often a pipe, but also sometimes files or special devices |
|
|
1786 | (for example, \f(CW\*(C`epoll\*(C'\fR on Linux works with \fI/dev/random\fR but not with |
|
|
1787 | \&\fI/dev/urandom\fR), and even though the file might better be served with |
|
|
1788 | asynchronous I/O instead of with non-blocking I/O, it is still useful when |
|
|
1789 | it \*(L"just works\*(R" instead of freezing. |
|
|
1790 | .PP |
|
|
1791 | So avoid file descriptors pointing to files when you know it (e.g. use |
|
|
1792 | libeio), but use them when it is convenient, e.g. for \s-1STDIN/STDOUT,\s0 or |
|
|
1793 | when you rarely read from a file instead of from a socket, and want to |
|
|
1794 | reuse the same code path. |
|
|
1795 | .PP |
1748 | \fIThe special problem of fork\fR |
1796 | \fIThe special problem of fork\fR |
1749 | .IX Subsection "The special problem of fork" |
1797 | .IX Subsection "The special problem of fork" |
1750 | .PP |
1798 | .PP |
1751 | Some backends (epoll, kqueue) do not support \f(CW\*(C`fork ()\*(C'\fR at all or exhibit |
1799 | Some backends (epoll, kqueue) do not support \f(CW\*(C`fork ()\*(C'\fR at all or exhibit |
1752 | useless behaviour. Libev fully supports fork, but needs to be told about |
1800 | useless behaviour. Libev fully supports fork, but needs to be told about |
1753 | it in the child. |
1801 | it in the child if you want to continue to use it in the child. |
1754 | .PP |
1802 | .PP |
1755 | To support fork in your programs, you either have to call |
1803 | To support fork in your child processes, you have to call \f(CW\*(C`ev_loop_fork |
1756 | \&\f(CW\*(C`ev_default_fork ()\*(C'\fR or \f(CW\*(C`ev_loop_fork ()\*(C'\fR after a fork in the child, |
1804 | ()\*(C'\fR after a fork in the child, enable \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR, or resort to |
1757 | enable \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR, or resort to \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or |
1805 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
1758 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
|
|
1759 | .PP |
1806 | .PP |
1760 | \fIThe special problem of \s-1SIGPIPE\s0\fR |
1807 | \fIThe special problem of \s-1SIGPIPE\s0\fR |
1761 | .IX Subsection "The special problem of SIGPIPE" |
1808 | .IX Subsection "The special problem of SIGPIPE" |
1762 | .PP |
1809 | .PP |
1763 | While not really specific to libev, it is easy to forget about \f(CW\*(C`SIGPIPE\*(C'\fR: |
1810 | While not really specific to libev, it is easy to forget about \f(CW\*(C`SIGPIPE\*(C'\fR: |
1764 | when writing to a pipe whose other end has been closed, your program gets |
1811 | when writing to a pipe whose other end has been closed, your program gets |
1765 | sent a \s-1SIGPIPE\s0, which, by default, aborts your program. For most programs |
1812 | sent a \s-1SIGPIPE,\s0 which, by default, aborts your program. For most programs |
1766 | this is sensible behaviour, for daemons, this is usually undesirable. |
1813 | this is sensible behaviour, for daemons, this is usually undesirable. |
1767 | .PP |
1814 | .PP |
1768 | So when you encounter spurious, unexplained daemon exits, make sure you |
1815 | So when you encounter spurious, unexplained daemon exits, make sure you |
1769 | ignore \s-1SIGPIPE\s0 (and maybe make sure you log the exit status of your daemon |
1816 | ignore \s-1SIGPIPE \s0(and maybe make sure you log the exit status of your daemon |
1770 | somewhere, as that would have given you a big clue). |
1817 | somewhere, as that would have given you a big clue). |
1771 | .PP |
1818 | .PP |
1772 | \fIThe special problem of \fIaccept()\fIing when you can't\fR |
1819 | \fIThe special problem of \fIaccept()\fIing when you can't\fR |
1773 | .IX Subsection "The special problem of accept()ing when you can't" |
1820 | .IX Subsection "The special problem of accept()ing when you can't" |
1774 | .PP |
1821 | .PP |
1775 | Many implementations of the \s-1POSIX\s0 \f(CW\*(C`accept\*(C'\fR function (for example, |
1822 | Many implementations of the \s-1POSIX \s0\f(CW\*(C`accept\*(C'\fR function (for example, |
1776 | found in post\-2004 Linux) have the peculiar behaviour of not removing a |
1823 | found in post\-2004 Linux) have the peculiar behaviour of not removing a |
1777 | connection from the pending queue in all error cases. |
1824 | connection from the pending queue in all error cases. |
1778 | .PP |
1825 | .PP |
1779 | For example, larger servers often run out of file descriptors (because |
1826 | For example, larger servers often run out of file descriptors (because |
1780 | of resource limits), causing \f(CW\*(C`accept\*(C'\fR to fail with \f(CW\*(C`ENFILE\*(C'\fR but not |
1827 | of resource limits), causing \f(CW\*(C`accept\*(C'\fR to fail with \f(CW\*(C`ENFILE\*(C'\fR but not |
… | |
… | |
1861 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1908 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1862 | monotonic clock option helps a lot here). |
1909 | monotonic clock option helps a lot here). |
1863 | .PP |
1910 | .PP |
1864 | The callback is guaranteed to be invoked only \fIafter\fR its timeout has |
1911 | The callback is guaranteed to be invoked only \fIafter\fR its timeout has |
1865 | passed (not \fIat\fR, so on systems with very low-resolution clocks this |
1912 | passed (not \fIat\fR, so on systems with very low-resolution clocks this |
1866 | might introduce a small delay). If multiple timers become ready during the |
1913 | might introduce a small delay, see \*(L"the special problem of being too |
|
|
1914 | early\*(R", below). If multiple timers become ready during the same loop |
1867 | same loop iteration then the ones with earlier time-out values are invoked |
1915 | iteration then the ones with earlier time-out values are invoked before |
1868 | before ones of the same priority with later time-out values (but this is |
1916 | ones of the same priority with later time-out values (but this is no |
1869 | no longer true when a callback calls \f(CW\*(C`ev_run\*(C'\fR recursively). |
1917 | longer true when a callback calls \f(CW\*(C`ev_run\*(C'\fR recursively). |
1870 | .PP |
1918 | .PP |
1871 | \fIBe smart about timeouts\fR |
1919 | \fIBe smart about timeouts\fR |
1872 | .IX Subsection "Be smart about timeouts" |
1920 | .IX Subsection "Be smart about timeouts" |
1873 | .PP |
1921 | .PP |
1874 | Many real-world problems involve some kind of timeout, usually for error |
1922 | Many real-world problems involve some kind of timeout, usually for error |
… | |
… | |
1956 | .Sp |
2004 | .Sp |
1957 | In this case, it would be more efficient to leave the \f(CW\*(C`ev_timer\*(C'\fR alone, |
2005 | In this case, it would be more efficient to leave the \f(CW\*(C`ev_timer\*(C'\fR alone, |
1958 | but remember the time of last activity, and check for a real timeout only |
2006 | but remember the time of last activity, and check for a real timeout only |
1959 | within the callback: |
2007 | within the callback: |
1960 | .Sp |
2008 | .Sp |
1961 | .Vb 1 |
2009 | .Vb 3 |
|
|
2010 | \& ev_tstamp timeout = 60.; |
1962 | \& ev_tstamp last_activity; // time of last activity |
2011 | \& ev_tstamp last_activity; // time of last activity |
|
|
2012 | \& ev_timer timer; |
1963 | \& |
2013 | \& |
1964 | \& static void |
2014 | \& static void |
1965 | \& callback (EV_P_ ev_timer *w, int revents) |
2015 | \& callback (EV_P_ ev_timer *w, int revents) |
1966 | \& { |
2016 | \& { |
1967 | \& ev_tstamp now = ev_now (EV_A); |
2017 | \& // calculate when the timeout would happen |
1968 | \& ev_tstamp timeout = last_activity + 60.; |
2018 | \& ev_tstamp after = last_activity \- ev_now (EV_A) + timeout; |
1969 | \& |
2019 | \& |
1970 | \& // if last_activity + 60. is older than now, we did time out |
2020 | \& // if negative, it means we the timeout already occurred |
1971 | \& if (timeout < now) |
2021 | \& if (after < 0.) |
1972 | \& { |
2022 | \& { |
1973 | \& // timeout occurred, take action |
2023 | \& // timeout occurred, take action |
1974 | \& } |
2024 | \& } |
1975 | \& else |
2025 | \& else |
1976 | \& { |
2026 | \& { |
1977 | \& // callback was invoked, but there was some activity, re\-arm |
2027 | \& // callback was invoked, but there was some recent |
1978 | \& // the watcher to fire in last_activity + 60, which is |
2028 | \& // activity. simply restart the timer to time out |
1979 | \& // guaranteed to be in the future, so "again" is positive: |
2029 | \& // after "after" seconds, which is the earliest time |
1980 | \& w\->repeat = timeout \- now; |
2030 | \& // the timeout can occur. |
|
|
2031 | \& ev_timer_set (w, after, 0.); |
1981 | \& ev_timer_again (EV_A_ w); |
2032 | \& ev_timer_start (EV_A_ w); |
1982 | \& } |
2033 | \& } |
1983 | \& } |
2034 | \& } |
1984 | .Ve |
2035 | .Ve |
1985 | .Sp |
2036 | .Sp |
1986 | To summarise the callback: first calculate the real timeout (defined |
2037 | To summarise the callback: first calculate in how many seconds the |
1987 | as \*(L"60 seconds after the last activity\*(R"), then check if that time has |
2038 | timeout will occur (by calculating the absolute time when it would occur, |
1988 | been reached, which means something \fIdid\fR, in fact, time out. Otherwise |
2039 | \&\f(CW\*(C`last_activity + timeout\*(C'\fR, and subtracting the current time, \f(CW\*(C`ev_now |
1989 | the callback was invoked too early (\f(CW\*(C`timeout\*(C'\fR is in the future), so |
2040 | (EV_A)\*(C'\fR from that). |
1990 | re-schedule the timer to fire at that future time, to see if maybe we have |
|
|
1991 | a timeout then. |
|
|
1992 | .Sp |
2041 | .Sp |
1993 | Note how \f(CW\*(C`ev_timer_again\*(C'\fR is used, taking advantage of the |
2042 | If this value is negative, then we are already past the timeout, i.e. we |
1994 | \&\f(CW\*(C`ev_timer_again\*(C'\fR optimisation when the timer is already running. |
2043 | timed out, and need to do whatever is needed in this case. |
|
|
2044 | .Sp |
|
|
2045 | Otherwise, we now the earliest time at which the timeout would trigger, |
|
|
2046 | and simply start the timer with this timeout value. |
|
|
2047 | .Sp |
|
|
2048 | In other words, each time the callback is invoked it will check whether |
|
|
2049 | the timeout occurred. If not, it will simply reschedule itself to check |
|
|
2050 | again at the earliest time it could time out. Rinse. Repeat. |
1995 | .Sp |
2051 | .Sp |
1996 | This scheme causes more callback invocations (about one every 60 seconds |
2052 | This scheme causes more callback invocations (about one every 60 seconds |
1997 | minus half the average time between activity), but virtually no calls to |
2053 | minus half the average time between activity), but virtually no calls to |
1998 | libev to change the timeout. |
2054 | libev to change the timeout. |
1999 | .Sp |
2055 | .Sp |
2000 | To start the timer, simply initialise the watcher and set \f(CW\*(C`last_activity\*(C'\fR |
2056 | To start the machinery, simply initialise the watcher and set |
2001 | to the current time (meaning we just have some activity :), then call the |
2057 | \&\f(CW\*(C`last_activity\*(C'\fR to the current time (meaning there was some activity just |
2002 | callback, which will \*(L"do the right thing\*(R" and start the timer: |
2058 | now), then call the callback, which will \*(L"do the right thing\*(R" and start |
|
|
2059 | the timer: |
2003 | .Sp |
2060 | .Sp |
2004 | .Vb 3 |
2061 | .Vb 3 |
|
|
2062 | \& last_activity = ev_now (EV_A); |
2005 | \& ev_init (timer, callback); |
2063 | \& ev_init (&timer, callback); |
2006 | \& last_activity = ev_now (loop); |
2064 | \& callback (EV_A_ &timer, 0); |
2007 | \& callback (loop, timer, EV_TIMER); |
|
|
2008 | .Ve |
2065 | .Ve |
2009 | .Sp |
2066 | .Sp |
2010 | And when there is some activity, simply store the current time in |
2067 | When there is some activity, simply store the current time in |
2011 | \&\f(CW\*(C`last_activity\*(C'\fR, no libev calls at all: |
2068 | \&\f(CW\*(C`last_activity\*(C'\fR, no libev calls at all: |
2012 | .Sp |
2069 | .Sp |
2013 | .Vb 1 |
2070 | .Vb 2 |
|
|
2071 | \& if (activity detected) |
2014 | \& last_activity = ev_now (loop); |
2072 | \& last_activity = ev_now (EV_A); |
|
|
2073 | .Ve |
|
|
2074 | .Sp |
|
|
2075 | When your timeout value changes, then the timeout can be changed by simply |
|
|
2076 | providing a new value, stopping the timer and calling the callback, which |
|
|
2077 | will again do the right thing (for example, time out immediately :). |
|
|
2078 | .Sp |
|
|
2079 | .Vb 3 |
|
|
2080 | \& timeout = new_value; |
|
|
2081 | \& ev_timer_stop (EV_A_ &timer); |
|
|
2082 | \& callback (EV_A_ &timer, 0); |
2015 | .Ve |
2083 | .Ve |
2016 | .Sp |
2084 | .Sp |
2017 | This technique is slightly more complex, but in most cases where the |
2085 | This technique is slightly more complex, but in most cases where the |
2018 | time-out is unlikely to be triggered, much more efficient. |
2086 | time-out is unlikely to be triggered, much more efficient. |
2019 | .Sp |
|
|
2020 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
|
|
2021 | callback :) \- just change the timeout and invoke the callback, which will |
|
|
2022 | fix things for you. |
|
|
2023 | .IP "4. Wee, just use a double-linked list for your timeouts." 4 |
2087 | .IP "4. Wee, just use a double-linked list for your timeouts." 4 |
2024 | .IX Item "4. Wee, just use a double-linked list for your timeouts." |
2088 | .IX Item "4. Wee, just use a double-linked list for your timeouts." |
2025 | If there is not one request, but many thousands (millions...), all |
2089 | If there is not one request, but many thousands (millions...), all |
2026 | employing some kind of timeout with the same timeout value, then one can |
2090 | employing some kind of timeout with the same timeout value, then one can |
2027 | do even better: |
2091 | do even better: |
… | |
… | |
2051 | Method #1 is almost always a bad idea, and buys you nothing. Method #4 is |
2115 | Method #1 is almost always a bad idea, and buys you nothing. Method #4 is |
2052 | rather complicated, but extremely efficient, something that really pays |
2116 | rather complicated, but extremely efficient, something that really pays |
2053 | off after the first million or so of active timers, i.e. it's usually |
2117 | off after the first million or so of active timers, i.e. it's usually |
2054 | overkill :) |
2118 | overkill :) |
2055 | .PP |
2119 | .PP |
|
|
2120 | \fIThe special problem of being too early\fR |
|
|
2121 | .IX Subsection "The special problem of being too early" |
|
|
2122 | .PP |
|
|
2123 | If you ask a timer to call your callback after three seconds, then |
|
|
2124 | you expect it to be invoked after three seconds \- but of course, this |
|
|
2125 | cannot be guaranteed to infinite precision. Less obviously, it cannot be |
|
|
2126 | guaranteed to any precision by libev \- imagine somebody suspending the |
|
|
2127 | process with a \s-1STOP\s0 signal for a few hours for example. |
|
|
2128 | .PP |
|
|
2129 | So, libev tries to invoke your callback as soon as possible \fIafter\fR the |
|
|
2130 | delay has occurred, but cannot guarantee this. |
|
|
2131 | .PP |
|
|
2132 | A less obvious failure mode is calling your callback too early: many event |
|
|
2133 | loops compare timestamps with a \*(L"elapsed delay >= requested delay\*(R", but |
|
|
2134 | this can cause your callback to be invoked much earlier than you would |
|
|
2135 | expect. |
|
|
2136 | .PP |
|
|
2137 | To see why, imagine a system with a clock that only offers full second |
|
|
2138 | resolution (think windows if you can't come up with a broken enough \s-1OS\s0 |
|
|
2139 | yourself). If you schedule a one-second timer at the time 500.9, then the |
|
|
2140 | event loop will schedule your timeout to elapse at a system time of 500 |
|
|
2141 | (500.9 truncated to the resolution) + 1, or 501. |
|
|
2142 | .PP |
|
|
2143 | If an event library looks at the timeout 0.1s later, it will see \*(L"501 >= |
|
|
2144 | 501\*(R" and invoke the callback 0.1s after it was started, even though a |
|
|
2145 | one-second delay was requested \- this is being \*(L"too early\*(R", despite best |
|
|
2146 | intentions. |
|
|
2147 | .PP |
|
|
2148 | This is the reason why libev will never invoke the callback if the elapsed |
|
|
2149 | delay equals the requested delay, but only when the elapsed delay is |
|
|
2150 | larger than the requested delay. In the example above, libev would only invoke |
|
|
2151 | the callback at system time 502, or 1.1s after the timer was started. |
|
|
2152 | .PP |
|
|
2153 | So, while libev cannot guarantee that your callback will be invoked |
|
|
2154 | exactly when requested, it \fIcan\fR and \fIdoes\fR guarantee that the requested |
|
|
2155 | delay has actually elapsed, or in other words, it always errs on the \*(L"too |
|
|
2156 | late\*(R" side of things. |
|
|
2157 | .PP |
2056 | \fIThe special problem of time updates\fR |
2158 | \fIThe special problem of time updates\fR |
2057 | .IX Subsection "The special problem of time updates" |
2159 | .IX Subsection "The special problem of time updates" |
2058 | .PP |
2160 | .PP |
2059 | Establishing the current time is a costly operation (it usually takes at |
2161 | Establishing the current time is a costly operation (it usually takes |
2060 | least two system calls): \s-1EV\s0 therefore updates its idea of the current |
2162 | at least one system call): \s-1EV\s0 therefore updates its idea of the current |
2061 | time only before and after \f(CW\*(C`ev_run\*(C'\fR collects new events, which causes a |
2163 | time only before and after \f(CW\*(C`ev_run\*(C'\fR collects new events, which causes a |
2062 | growing difference between \f(CW\*(C`ev_now ()\*(C'\fR and \f(CW\*(C`ev_time ()\*(C'\fR when handling |
2164 | growing difference between \f(CW\*(C`ev_now ()\*(C'\fR and \f(CW\*(C`ev_time ()\*(C'\fR when handling |
2063 | lots of events in one iteration. |
2165 | lots of events in one iteration. |
2064 | .PP |
2166 | .PP |
2065 | The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR |
2167 | The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR |
2066 | time. This is usually the right thing as this timestamp refers to the time |
2168 | time. This is usually the right thing as this timestamp refers to the time |
2067 | of the event triggering whatever timeout you are modifying/starting. If |
2169 | of the event triggering whatever timeout you are modifying/starting. If |
2068 | you suspect event processing to be delayed and you \fIneed\fR to base the |
2170 | you suspect event processing to be delayed and you \fIneed\fR to base the |
2069 | timeout on the current time, use something like this to adjust for this: |
2171 | timeout on the current time, use something like the following to adjust |
|
|
2172 | for it: |
2070 | .PP |
2173 | .PP |
2071 | .Vb 1 |
2174 | .Vb 1 |
2072 | \& ev_timer_set (&timer, after + ev_now () \- ev_time (), 0.); |
2175 | \& ev_timer_set (&timer, after + (ev_time () \- ev_now ()), 0.); |
2073 | .Ve |
2176 | .Ve |
2074 | .PP |
2177 | .PP |
2075 | If the event loop is suspended for a long time, you can also force an |
2178 | If the event loop is suspended for a long time, you can also force an |
2076 | update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update |
2179 | update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update |
2077 | ()\*(C'\fR. |
2180 | ()\*(C'\fR, although that will push the event time of all outstanding events |
|
|
2181 | further into the future. |
|
|
2182 | .PP |
|
|
2183 | \fIThe special problem of unsynchronised clocks\fR |
|
|
2184 | .IX Subsection "The special problem of unsynchronised clocks" |
|
|
2185 | .PP |
|
|
2186 | Modern systems have a variety of clocks \- libev itself uses the normal |
|
|
2187 | \&\*(L"wall clock\*(R" clock and, if available, the monotonic clock (to avoid time |
|
|
2188 | jumps). |
|
|
2189 | .PP |
|
|
2190 | Neither of these clocks is synchronised with each other or any other clock |
|
|
2191 | on the system, so \f(CW\*(C`ev_time ()\*(C'\fR might return a considerably different time |
|
|
2192 | than \f(CW\*(C`gettimeofday ()\*(C'\fR or \f(CW\*(C`time ()\*(C'\fR. On a GNU/Linux system, for example, |
|
|
2193 | a call to \f(CW\*(C`gettimeofday\*(C'\fR might return a second count that is one higher |
|
|
2194 | than a directly following call to \f(CW\*(C`time\*(C'\fR. |
|
|
2195 | .PP |
|
|
2196 | The moral of this is to only compare libev-related timestamps with |
|
|
2197 | \&\f(CW\*(C`ev_time ()\*(C'\fR and \f(CW\*(C`ev_now ()\*(C'\fR, at least if you want better precision than |
|
|
2198 | a second or so. |
|
|
2199 | .PP |
|
|
2200 | One more problem arises due to this lack of synchronisation: if libev uses |
|
|
2201 | the system monotonic clock and you compare timestamps from \f(CW\*(C`ev_time\*(C'\fR |
|
|
2202 | or \f(CW\*(C`ev_now\*(C'\fR from when you started your timer and when your callback is |
|
|
2203 | invoked, you will find that sometimes the callback is a bit \*(L"early\*(R". |
|
|
2204 | .PP |
|
|
2205 | This is because \f(CW\*(C`ev_timer\*(C'\fRs work in real time, not wall clock time, so |
|
|
2206 | libev makes sure your callback is not invoked before the delay happened, |
|
|
2207 | \&\fImeasured according to the real time\fR, not the system clock. |
|
|
2208 | .PP |
|
|
2209 | If your timeouts are based on a physical timescale (e.g. \*(L"time out this |
|
|
2210 | connection after 100 seconds\*(R") then this shouldn't bother you as it is |
|
|
2211 | exactly the right behaviour. |
|
|
2212 | .PP |
|
|
2213 | If you want to compare wall clock/system timestamps to your timers, then |
|
|
2214 | you need to use \f(CW\*(C`ev_periodic\*(C'\fRs, as these are based on the wall clock |
|
|
2215 | time, where your comparisons will always generate correct results. |
2078 | .PP |
2216 | .PP |
2079 | \fIThe special problems of suspended animation\fR |
2217 | \fIThe special problems of suspended animation\fR |
2080 | .IX Subsection "The special problems of suspended animation" |
2218 | .IX Subsection "The special problems of suspended animation" |
2081 | .PP |
2219 | .PP |
2082 | When you leave the server world it is quite customary to hit machines that |
2220 | When you leave the server world it is quite customary to hit machines that |
… | |
… | |
2126 | trigger at exactly 10 second intervals. If, however, your program cannot |
2264 | trigger at exactly 10 second intervals. If, however, your program cannot |
2127 | keep up with the timer (because it takes longer than those 10 seconds to |
2265 | keep up with the timer (because it takes longer than those 10 seconds to |
2128 | do stuff) the timer will not fire more than once per event loop iteration. |
2266 | do stuff) the timer will not fire more than once per event loop iteration. |
2129 | .IP "ev_timer_again (loop, ev_timer *)" 4 |
2267 | .IP "ev_timer_again (loop, ev_timer *)" 4 |
2130 | .IX Item "ev_timer_again (loop, ev_timer *)" |
2268 | .IX Item "ev_timer_again (loop, ev_timer *)" |
2131 | This will act as if the timer timed out and restart it again if it is |
2269 | This will act as if the timer timed out, and restarts it again if it is |
2132 | repeating. The exact semantics are: |
2270 | repeating. It basically works like calling \f(CW\*(C`ev_timer_stop\*(C'\fR, updating the |
|
|
2271 | timeout to the \f(CW\*(C`repeat\*(C'\fR value and calling \f(CW\*(C`ev_timer_start\*(C'\fR. |
2133 | .Sp |
2272 | .Sp |
|
|
2273 | The exact semantics are as in the following rules, all of which will be |
|
|
2274 | applied to the watcher: |
|
|
2275 | .RS 4 |
2134 | If the timer is pending, its pending status is cleared. |
2276 | .IP "If the timer is pending, the pending status is always cleared." 4 |
2135 | .Sp |
2277 | .IX Item "If the timer is pending, the pending status is always cleared." |
|
|
2278 | .PD 0 |
2136 | If the timer is started but non-repeating, stop it (as if it timed out). |
2279 | .IP "If the timer is started but non-repeating, stop it (as if it timed out, without invoking it)." 4 |
2137 | .Sp |
2280 | .IX Item "If the timer is started but non-repeating, stop it (as if it timed out, without invoking it)." |
2138 | If the timer is repeating, either start it if necessary (with the |
2281 | .ie n .IP "If the timer is repeating, make the ""repeat"" value the new timeout and start the timer, if necessary." 4 |
2139 | \&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value. |
2282 | .el .IP "If the timer is repeating, make the \f(CWrepeat\fR value the new timeout and start the timer, if necessary." 4 |
|
|
2283 | .IX Item "If the timer is repeating, make the repeat value the new timeout and start the timer, if necessary." |
|
|
2284 | .RE |
|
|
2285 | .RS 4 |
|
|
2286 | .PD |
2140 | .Sp |
2287 | .Sp |
2141 | This sounds a bit complicated, see \*(L"Be smart about timeouts\*(R", above, for a |
2288 | This sounds a bit complicated, see \*(L"Be smart about timeouts\*(R", above, for a |
2142 | usage example. |
2289 | usage example. |
|
|
2290 | .RE |
2143 | .IP "ev_tstamp ev_timer_remaining (loop, ev_timer *)" 4 |
2291 | .IP "ev_tstamp ev_timer_remaining (loop, ev_timer *)" 4 |
2144 | .IX Item "ev_tstamp ev_timer_remaining (loop, ev_timer *)" |
2292 | .IX Item "ev_tstamp ev_timer_remaining (loop, ev_timer *)" |
2145 | Returns the remaining time until a timer fires. If the timer is active, |
2293 | Returns the remaining time until a timer fires. If the timer is active, |
2146 | then this time is relative to the current event loop time, otherwise it's |
2294 | then this time is relative to the current event loop time, otherwise it's |
2147 | the timeout value currently configured. |
2295 | the timeout value currently configured. |
… | |
… | |
2199 | Periodic watchers are also timers of a kind, but they are very versatile |
2347 | Periodic watchers are also timers of a kind, but they are very versatile |
2200 | (and unfortunately a bit complex). |
2348 | (and unfortunately a bit complex). |
2201 | .PP |
2349 | .PP |
2202 | Unlike \f(CW\*(C`ev_timer\*(C'\fR, periodic watchers are not based on real time (or |
2350 | Unlike \f(CW\*(C`ev_timer\*(C'\fR, periodic watchers are not based on real time (or |
2203 | relative time, the physical time that passes) but on wall clock time |
2351 | relative time, the physical time that passes) but on wall clock time |
2204 | (absolute time, the thing you can read on your calender or clock). The |
2352 | (absolute time, the thing you can read on your calendar or clock). The |
2205 | difference is that wall clock time can run faster or slower than real |
2353 | difference is that wall clock time can run faster or slower than real |
2206 | time, and time jumps are not uncommon (e.g. when you adjust your |
2354 | time, and time jumps are not uncommon (e.g. when you adjust your |
2207 | wrist-watch). |
2355 | wrist-watch). |
2208 | .PP |
2356 | .PP |
2209 | You can tell a periodic watcher to trigger after some specific point |
2357 | You can tell a periodic watcher to trigger after some specific point |
… | |
… | |
2267 | .Sp |
2415 | .Sp |
2268 | Another way to think about it (for the mathematically inclined) is that |
2416 | Another way to think about it (for the mathematically inclined) is that |
2269 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
2417 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
2270 | time where \f(CW\*(C`time = offset (mod interval)\*(C'\fR, regardless of any time jumps. |
2418 | time where \f(CW\*(C`time = offset (mod interval)\*(C'\fR, regardless of any time jumps. |
2271 | .Sp |
2419 | .Sp |
2272 | For numerical stability it is preferable that the \f(CW\*(C`offset\*(C'\fR value is near |
2420 | The \f(CW\*(C`interval\*(C'\fR \fI\s-1MUST\s0\fR be positive, and for numerical stability, the |
2273 | \&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for |
2421 | interval value should be higher than \f(CW\*(C`1/8192\*(C'\fR (which is around 100 |
2274 | this value, and in fact is often specified as zero. |
2422 | microseconds) and \f(CW\*(C`offset\*(C'\fR should be higher than \f(CW0\fR and should have |
|
|
2423 | at most a similar magnitude as the current time (say, within a factor of |
|
|
2424 | ten). Typical values for offset are, in fact, \f(CW0\fR or something between |
|
|
2425 | \&\f(CW0\fR and \f(CW\*(C`interval\*(C'\fR, which is also the recommended range. |
2275 | .Sp |
2426 | .Sp |
2276 | Note also that there is an upper limit to how often a timer can fire (\s-1CPU\s0 |
2427 | Note also that there is an upper limit to how often a timer can fire (\s-1CPU\s0 |
2277 | speed for example), so if \f(CW\*(C`interval\*(C'\fR is very small then timing stability |
2428 | speed for example), so if \f(CW\*(C`interval\*(C'\fR is very small then timing stability |
2278 | will of course deteriorate. Libev itself tries to be exact to be about one |
2429 | will of course deteriorate. Libev itself tries to be exact to be about one |
2279 | millisecond (if the \s-1OS\s0 supports it and the machine is fast enough). |
2430 | millisecond (if the \s-1OS\s0 supports it and the machine is fast enough). |
… | |
… | |
2283 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`offset\*(C'\fR are both being |
2434 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`offset\*(C'\fR are both being |
2284 | ignored. Instead, each time the periodic watcher gets scheduled, the |
2435 | ignored. Instead, each time the periodic watcher gets scheduled, the |
2285 | reschedule callback will be called with the watcher as first, and the |
2436 | reschedule callback will be called with the watcher as first, and the |
2286 | current time as second argument. |
2437 | current time as second argument. |
2287 | .Sp |
2438 | .Sp |
2288 | \&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, ever, |
2439 | \&\s-1NOTE: \s0\fIThis callback \s-1MUST NOT\s0 stop or destroy any periodic watcher, ever, |
2289 | or make \s-1ANY\s0 other event loop modifications whatsoever, unless explicitly |
2440 | or make \s-1ANY\s0 other event loop modifications whatsoever, unless explicitly |
2290 | allowed by documentation here\fR. |
2441 | allowed by documentation here\fR. |
2291 | .Sp |
2442 | .Sp |
2292 | If you need to stop it, return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop |
2443 | If you need to stop it, return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop |
2293 | it afterwards (e.g. by starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is the |
2444 | it afterwards (e.g. by starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is the |
… | |
… | |
2307 | It must return the next time to trigger, based on the passed time value |
2458 | It must return the next time to trigger, based on the passed time value |
2308 | (that is, the lowest time value larger than to the second argument). It |
2459 | (that is, the lowest time value larger than to the second argument). It |
2309 | will usually be called just before the callback will be triggered, but |
2460 | will usually be called just before the callback will be triggered, but |
2310 | might be called at other times, too. |
2461 | might be called at other times, too. |
2311 | .Sp |
2462 | .Sp |
2312 | \&\s-1NOTE:\s0 \fIThis callback must always return a time that is higher than or |
2463 | \&\s-1NOTE: \s0\fIThis callback must always return a time that is higher than or |
2313 | equal to the passed \f(CI\*(C`now\*(C'\fI value\fR. |
2464 | equal to the passed \f(CI\*(C`now\*(C'\fI value\fR. |
2314 | .Sp |
2465 | .Sp |
2315 | This can be used to create very complex timers, such as a timer that |
2466 | This can be used to create very complex timers, such as a timer that |
2316 | triggers on \*(L"next midnight, local time\*(R". To do this, you would calculate the |
2467 | triggers on \*(L"next midnight, local time\*(R". To do this, you would calculate the |
2317 | next midnight after \f(CW\*(C`now\*(C'\fR and return the timestamp value for this. How |
2468 | next midnight after \f(CW\*(C`now\*(C'\fR and return the timestamp value for this. How |
… | |
… | |
2409 | only within the same loop, i.e. you can watch for \f(CW\*(C`SIGINT\*(C'\fR in your |
2560 | only within the same loop, i.e. you can watch for \f(CW\*(C`SIGINT\*(C'\fR in your |
2410 | default loop and for \f(CW\*(C`SIGIO\*(C'\fR in another loop, but you cannot watch for |
2561 | default loop and for \f(CW\*(C`SIGIO\*(C'\fR in another loop, but you cannot watch for |
2411 | \&\f(CW\*(C`SIGINT\*(C'\fR in both the default loop and another loop at the same time. At |
2562 | \&\f(CW\*(C`SIGINT\*(C'\fR in both the default loop and another loop at the same time. At |
2412 | the moment, \f(CW\*(C`SIGCHLD\*(C'\fR is permanently tied to the default loop. |
2563 | the moment, \f(CW\*(C`SIGCHLD\*(C'\fR is permanently tied to the default loop. |
2413 | .PP |
2564 | .PP |
2414 | When the first watcher gets started will libev actually register something |
2565 | Only after the first watcher for a signal is started will libev actually |
2415 | with the kernel (thus it coexists with your own signal handlers as long as |
2566 | register something with the kernel. It thus coexists with your own signal |
2416 | you don't register any with libev for the same signal). |
2567 | handlers as long as you don't register any with libev for the same signal. |
2417 | .PP |
2568 | .PP |
2418 | If possible and supported, libev will install its handlers with |
2569 | If possible and supported, libev will install its handlers with |
2419 | \&\f(CW\*(C`SA_RESTART\*(C'\fR (or equivalent) behaviour enabled, so system calls should |
2570 | \&\f(CW\*(C`SA_RESTART\*(C'\fR (or equivalent) behaviour enabled, so system calls should |
2420 | not be unduly interrupted. If you have a problem with system calls getting |
2571 | not be unduly interrupted. If you have a problem with system calls getting |
2421 | interrupted by signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher |
2572 | interrupted by signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher |
… | |
… | |
2425 | .IX Subsection "The special problem of inheritance over fork/execve/pthread_create" |
2576 | .IX Subsection "The special problem of inheritance over fork/execve/pthread_create" |
2426 | .PP |
2577 | .PP |
2427 | Both the signal mask (\f(CW\*(C`sigprocmask\*(C'\fR) and the signal disposition |
2578 | Both the signal mask (\f(CW\*(C`sigprocmask\*(C'\fR) and the signal disposition |
2428 | (\f(CW\*(C`sigaction\*(C'\fR) are unspecified after starting a signal watcher (and after |
2579 | (\f(CW\*(C`sigaction\*(C'\fR) are unspecified after starting a signal watcher (and after |
2429 | stopping it again), that is, libev might or might not block the signal, |
2580 | stopping it again), that is, libev might or might not block the signal, |
2430 | and might or might not set or restore the installed signal handler. |
2581 | and might or might not set or restore the installed signal handler (but |
|
|
2582 | see \f(CW\*(C`EVFLAG_NOSIGMASK\*(C'\fR). |
2431 | .PP |
2583 | .PP |
2432 | While this does not matter for the signal disposition (libev never |
2584 | While this does not matter for the signal disposition (libev never |
2433 | sets signals to \f(CW\*(C`SIG_IGN\*(C'\fR, so handlers will be reset to \f(CW\*(C`SIG_DFL\*(C'\fR on |
2585 | sets signals to \f(CW\*(C`SIG_IGN\*(C'\fR, so handlers will be reset to \f(CW\*(C`SIG_DFL\*(C'\fR on |
2434 | \&\f(CW\*(C`execve\*(C'\fR), this matters for the signal mask: many programs do not expect |
2586 | \&\f(CW\*(C`execve\*(C'\fR), this matters for the signal mask: many programs do not expect |
2435 | certain signals to be blocked. |
2587 | certain signals to be blocked. |
… | |
… | |
2441 | The simplest way to ensure that the signal mask is reset in the child is |
2593 | The simplest way to ensure that the signal mask is reset in the child is |
2442 | to install a fork handler with \f(CW\*(C`pthread_atfork\*(C'\fR that resets it. That will |
2594 | to install a fork handler with \f(CW\*(C`pthread_atfork\*(C'\fR that resets it. That will |
2443 | catch fork calls done by libraries (such as the libc) as well. |
2595 | catch fork calls done by libraries (such as the libc) as well. |
2444 | .PP |
2596 | .PP |
2445 | In current versions of libev, the signal will not be blocked indefinitely |
2597 | In current versions of libev, the signal will not be blocked indefinitely |
2446 | unless you use the \f(CW\*(C`signalfd\*(C'\fR \s-1API\s0 (\f(CW\*(C`EV_SIGNALFD\*(C'\fR). While this reduces |
2598 | unless you use the \f(CW\*(C`signalfd\*(C'\fR \s-1API \s0(\f(CW\*(C`EV_SIGNALFD\*(C'\fR). While this reduces |
2447 | the window of opportunity for problems, it will not go away, as libev |
2599 | the window of opportunity for problems, it will not go away, as libev |
2448 | \&\fIhas\fR to modify the signal mask, at least temporarily. |
2600 | \&\fIhas\fR to modify the signal mask, at least temporarily. |
2449 | .PP |
2601 | .PP |
2450 | So I can't stress this enough: \fIIf you do not reset your signal mask when |
2602 | So I can't stress this enough: \fIIf you do not reset your signal mask when |
2451 | you expect it to be empty, you have a race condition in your code\fR. This |
2603 | you expect it to be empty, you have a race condition in your code\fR. This |
2452 | is not a libev-specific thing, this is true for most event libraries. |
2604 | is not a libev-specific thing, this is true for most event libraries. |
|
|
2605 | .PP |
|
|
2606 | \fIThe special problem of threads signal handling\fR |
|
|
2607 | .IX Subsection "The special problem of threads signal handling" |
|
|
2608 | .PP |
|
|
2609 | \&\s-1POSIX\s0 threads has problematic signal handling semantics, specifically, |
|
|
2610 | a lot of functionality (sigfd, sigwait etc.) only really works if all |
|
|
2611 | threads in a process block signals, which is hard to achieve. |
|
|
2612 | .PP |
|
|
2613 | When you want to use sigwait (or mix libev signal handling with your own |
|
|
2614 | for the same signals), you can tackle this problem by globally blocking |
|
|
2615 | all signals before creating any threads (or creating them with a fully set |
|
|
2616 | sigprocmask) and also specifying the \f(CW\*(C`EVFLAG_NOSIGMASK\*(C'\fR when creating |
|
|
2617 | loops. Then designate one thread as \*(L"signal receiver thread\*(R" which handles |
|
|
2618 | these signals. You can pass on any signals that libev might be interested |
|
|
2619 | in by calling \f(CW\*(C`ev_feed_signal\*(C'\fR. |
2453 | .PP |
2620 | .PP |
2454 | \fIWatcher-Specific Functions and Data Members\fR |
2621 | \fIWatcher-Specific Functions and Data Members\fR |
2455 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2622 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2456 | .IP "ev_signal_init (ev_signal *, callback, int signum)" 4 |
2623 | .IP "ev_signal_init (ev_signal *, callback, int signum)" 4 |
2457 | .IX Item "ev_signal_init (ev_signal *, callback, int signum)" |
2624 | .IX Item "ev_signal_init (ev_signal *, callback, int signum)" |
… | |
… | |
2466 | The signal the watcher watches out for. |
2633 | The signal the watcher watches out for. |
2467 | .PP |
2634 | .PP |
2468 | \fIExamples\fR |
2635 | \fIExamples\fR |
2469 | .IX Subsection "Examples" |
2636 | .IX Subsection "Examples" |
2470 | .PP |
2637 | .PP |
2471 | Example: Try to exit cleanly on \s-1SIGINT\s0. |
2638 | Example: Try to exit cleanly on \s-1SIGINT.\s0 |
2472 | .PP |
2639 | .PP |
2473 | .Vb 5 |
2640 | .Vb 5 |
2474 | \& static void |
2641 | \& static void |
2475 | \& sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2642 | \& sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2476 | \& { |
2643 | \& { |
… | |
… | |
2591 | .ie n .SS """ev_stat"" \- did the file attributes just change?" |
2758 | .ie n .SS """ev_stat"" \- did the file attributes just change?" |
2592 | .el .SS "\f(CWev_stat\fP \- did the file attributes just change?" |
2759 | .el .SS "\f(CWev_stat\fP \- did the file attributes just change?" |
2593 | .IX Subsection "ev_stat - did the file attributes just change?" |
2760 | .IX Subsection "ev_stat - did the file attributes just change?" |
2594 | This watches a file system path for attribute changes. That is, it calls |
2761 | This watches a file system path for attribute changes. That is, it calls |
2595 | \&\f(CW\*(C`stat\*(C'\fR on that path in regular intervals (or when the \s-1OS\s0 says it changed) |
2762 | \&\f(CW\*(C`stat\*(C'\fR on that path in regular intervals (or when the \s-1OS\s0 says it changed) |
2596 | and sees if it changed compared to the last time, invoking the callback if |
2763 | and sees if it changed compared to the last time, invoking the callback |
2597 | it did. |
2764 | if it did. Starting the watcher \f(CW\*(C`stat\*(C'\fR's the file, so only changes that |
|
|
2765 | happen after the watcher has been started will be reported. |
2598 | .PP |
2766 | .PP |
2599 | The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does |
2767 | The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does |
2600 | not exist\*(R" is a status change like any other. The condition \*(L"path does not |
2768 | not exist\*(R" is a status change like any other. The condition \*(L"path does not |
2601 | exist\*(R" (or more correctly \*(L"path cannot be stat'ed\*(R") is signified by the |
2769 | exist\*(R" (or more correctly \*(L"path cannot be stat'ed\*(R") is signified by the |
2602 | \&\f(CW\*(C`st_nlink\*(C'\fR field being zero (which is otherwise always forced to be at |
2770 | \&\f(CW\*(C`st_nlink\*(C'\fR field being zero (which is otherwise always forced to be at |
… | |
… | |
2632 | compilation environment, which means that on systems with large file |
2800 | compilation environment, which means that on systems with large file |
2633 | support disabled by default, you get the 32 bit version of the stat |
2801 | support disabled by default, you get the 32 bit version of the stat |
2634 | structure. When using the library from programs that change the \s-1ABI\s0 to |
2802 | structure. When using the library from programs that change the \s-1ABI\s0 to |
2635 | use 64 bit file offsets the programs will fail. In that case you have to |
2803 | use 64 bit file offsets the programs will fail. In that case you have to |
2636 | compile libev with the same flags to get binary compatibility. This is |
2804 | compile libev with the same flags to get binary compatibility. This is |
2637 | obviously the case with any flags that change the \s-1ABI\s0, but the problem is |
2805 | obviously the case with any flags that change the \s-1ABI,\s0 but the problem is |
2638 | most noticeably displayed with ev_stat and large file support. |
2806 | most noticeably displayed with ev_stat and large file support. |
2639 | .PP |
2807 | .PP |
2640 | The solution for this is to lobby your distribution maker to make large |
2808 | The solution for this is to lobby your distribution maker to make large |
2641 | file interfaces available by default (as e.g. FreeBSD does) and not |
2809 | file interfaces available by default (as e.g. FreeBSD does) and not |
2642 | optional. Libev cannot simply switch on large file support because it has |
2810 | optional. Libev cannot simply switch on large file support because it has |
… | |
… | |
2833 | Apart from keeping your process non-blocking (which is a useful |
3001 | Apart from keeping your process non-blocking (which is a useful |
2834 | effect on its own sometimes), idle watchers are a good place to do |
3002 | effect on its own sometimes), idle watchers are a good place to do |
2835 | \&\*(L"pseudo-background processing\*(R", or delay processing stuff to after the |
3003 | \&\*(L"pseudo-background processing\*(R", or delay processing stuff to after the |
2836 | event loop has handled all outstanding events. |
3004 | event loop has handled all outstanding events. |
2837 | .PP |
3005 | .PP |
|
|
3006 | \fIAbusing an \f(CI\*(C`ev_idle\*(C'\fI watcher for its side-effect\fR |
|
|
3007 | .IX Subsection "Abusing an ev_idle watcher for its side-effect" |
|
|
3008 | .PP |
|
|
3009 | As long as there is at least one active idle watcher, libev will never |
|
|
3010 | sleep unnecessarily. Or in other words, it will loop as fast as possible. |
|
|
3011 | For this to work, the idle watcher doesn't need to be invoked at all \- the |
|
|
3012 | lowest priority will do. |
|
|
3013 | .PP |
|
|
3014 | This mode of operation can be useful together with an \f(CW\*(C`ev_check\*(C'\fR watcher, |
|
|
3015 | to do something on each event loop iteration \- for example to balance load |
|
|
3016 | between different connections. |
|
|
3017 | .PP |
|
|
3018 | See \*(L"Abusing an ev_check watcher for its side-effect\*(R" for a longer |
|
|
3019 | example. |
|
|
3020 | .PP |
2838 | \fIWatcher-Specific Functions and Data Members\fR |
3021 | \fIWatcher-Specific Functions and Data Members\fR |
2839 | .IX Subsection "Watcher-Specific Functions and Data Members" |
3022 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2840 | .IP "ev_idle_init (ev_idle *, callback)" 4 |
3023 | .IP "ev_idle_init (ev_idle *, callback)" 4 |
2841 | .IX Item "ev_idle_init (ev_idle *, callback)" |
3024 | .IX Item "ev_idle_init (ev_idle *, callback)" |
2842 | Initialises and configures the idle watcher \- it has no parameters of any |
3025 | Initialises and configures the idle watcher \- it has no parameters of any |
… | |
… | |
2847 | .IX Subsection "Examples" |
3030 | .IX Subsection "Examples" |
2848 | .PP |
3031 | .PP |
2849 | Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the |
3032 | Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the |
2850 | callback, free it. Also, use no error checking, as usual. |
3033 | callback, free it. Also, use no error checking, as usual. |
2851 | .PP |
3034 | .PP |
2852 | .Vb 7 |
3035 | .Vb 5 |
2853 | \& static void |
3036 | \& static void |
2854 | \& idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
3037 | \& idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
2855 | \& { |
3038 | \& { |
|
|
3039 | \& // stop the watcher |
|
|
3040 | \& ev_idle_stop (loop, w); |
|
|
3041 | \& |
|
|
3042 | \& // now we can free it |
2856 | \& free (w); |
3043 | \& free (w); |
|
|
3044 | \& |
2857 | \& // now do something you wanted to do when the program has |
3045 | \& // now do something you wanted to do when the program has |
2858 | \& // no longer anything immediate to do. |
3046 | \& // no longer anything immediate to do. |
2859 | \& } |
3047 | \& } |
2860 | \& |
3048 | \& |
2861 | \& ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
3049 | \& ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
… | |
… | |
2863 | \& ev_idle_start (loop, idle_watcher); |
3051 | \& ev_idle_start (loop, idle_watcher); |
2864 | .Ve |
3052 | .Ve |
2865 | .ie n .SS """ev_prepare"" and ""ev_check"" \- customise your event loop!" |
3053 | .ie n .SS """ev_prepare"" and ""ev_check"" \- customise your event loop!" |
2866 | .el .SS "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!" |
3054 | .el .SS "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!" |
2867 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
3055 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
2868 | Prepare and check watchers are usually (but not always) used in pairs: |
3056 | Prepare and check watchers are often (but not always) used in pairs: |
2869 | prepare watchers get invoked before the process blocks and check watchers |
3057 | prepare watchers get invoked before the process blocks and check watchers |
2870 | afterwards. |
3058 | afterwards. |
2871 | .PP |
3059 | .PP |
2872 | You \fImust not\fR call \f(CW\*(C`ev_run\*(C'\fR or similar functions that enter |
3060 | You \fImust not\fR call \f(CW\*(C`ev_run\*(C'\fR (or similar functions that enter the |
2873 | the current event loop from either \f(CW\*(C`ev_prepare\*(C'\fR or \f(CW\*(C`ev_check\*(C'\fR |
3061 | current event loop) or \f(CW\*(C`ev_loop_fork\*(C'\fR from either \f(CW\*(C`ev_prepare\*(C'\fR or |
2874 | watchers. Other loops than the current one are fine, however. The |
3062 | \&\f(CW\*(C`ev_check\*(C'\fR watchers. Other loops than the current one are fine, |
2875 | rationale behind this is that you do not need to check for recursion in |
3063 | however. The rationale behind this is that you do not need to check |
2876 | those watchers, i.e. the sequence will always be \f(CW\*(C`ev_prepare\*(C'\fR, blocking, |
3064 | for recursion in those watchers, i.e. the sequence will always be |
2877 | \&\f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each kind they will always be |
3065 | \&\f(CW\*(C`ev_prepare\*(C'\fR, blocking, \f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each |
2878 | called in pairs bracketing the blocking call. |
3066 | kind they will always be called in pairs bracketing the blocking call. |
2879 | .PP |
3067 | .PP |
2880 | Their main purpose is to integrate other event mechanisms into libev and |
3068 | Their main purpose is to integrate other event mechanisms into libev and |
2881 | their use is somewhat advanced. They could be used, for example, to track |
3069 | their use is somewhat advanced. They could be used, for example, to track |
2882 | variable changes, implement your own watchers, integrate net-snmp or a |
3070 | variable changes, implement your own watchers, integrate net-snmp or a |
2883 | coroutine library and lots more. They are also occasionally useful if |
3071 | coroutine library and lots more. They are also occasionally useful if |
… | |
… | |
2901 | with priority higher than or equal to the event loop and one coroutine |
3089 | with priority higher than or equal to the event loop and one coroutine |
2902 | of lower priority, but only once, using idle watchers to keep the event |
3090 | of lower priority, but only once, using idle watchers to keep the event |
2903 | loop from blocking if lower-priority coroutines are active, thus mapping |
3091 | loop from blocking if lower-priority coroutines are active, thus mapping |
2904 | low-priority coroutines to idle/background tasks). |
3092 | low-priority coroutines to idle/background tasks). |
2905 | .PP |
3093 | .PP |
2906 | It is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR) |
3094 | When used for this purpose, it is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers |
2907 | priority, to ensure that they are being run before any other watchers |
3095 | highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR) priority, to ensure that they are being run before |
2908 | after the poll (this doesn't matter for \f(CW\*(C`ev_prepare\*(C'\fR watchers). |
3096 | any other watchers after the poll (this doesn't matter for \f(CW\*(C`ev_prepare\*(C'\fR |
|
|
3097 | watchers). |
2909 | .PP |
3098 | .PP |
2910 | Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers, too) should not |
3099 | Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers, too) should not |
2911 | activate (\*(L"feed\*(R") events into libev. While libev fully supports this, they |
3100 | activate (\*(L"feed\*(R") events into libev. While libev fully supports this, they |
2912 | might get executed before other \f(CW\*(C`ev_check\*(C'\fR watchers did their job. As |
3101 | might get executed before other \f(CW\*(C`ev_check\*(C'\fR watchers did their job. As |
2913 | \&\f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other (non-libev) event |
3102 | \&\f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other (non-libev) event |
2914 | loops those other event loops might be in an unusable state until their |
3103 | loops those other event loops might be in an unusable state until their |
2915 | \&\f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to coexist peacefully with |
3104 | \&\f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to coexist peacefully with |
2916 | others). |
3105 | others). |
|
|
3106 | .PP |
|
|
3107 | \fIAbusing an \f(CI\*(C`ev_check\*(C'\fI watcher for its side-effect\fR |
|
|
3108 | .IX Subsection "Abusing an ev_check watcher for its side-effect" |
|
|
3109 | .PP |
|
|
3110 | \&\f(CW\*(C`ev_check\*(C'\fR (and less often also \f(CW\*(C`ev_prepare\*(C'\fR) watchers can also be |
|
|
3111 | useful because they are called once per event loop iteration. For |
|
|
3112 | example, if you want to handle a large number of connections fairly, you |
|
|
3113 | normally only do a bit of work for each active connection, and if there |
|
|
3114 | is more work to do, you wait for the next event loop iteration, so other |
|
|
3115 | connections have a chance of making progress. |
|
|
3116 | .PP |
|
|
3117 | Using an \f(CW\*(C`ev_check\*(C'\fR watcher is almost enough: it will be called on the |
|
|
3118 | next event loop iteration. However, that isn't as soon as possible \- |
|
|
3119 | without external events, your \f(CW\*(C`ev_check\*(C'\fR watcher will not be invoked. |
|
|
3120 | .PP |
|
|
3121 | This is where \f(CW\*(C`ev_idle\*(C'\fR watchers come in handy \- all you need is a |
|
|
3122 | single global idle watcher that is active as long as you have one active |
|
|
3123 | \&\f(CW\*(C`ev_check\*(C'\fR watcher. The \f(CW\*(C`ev_idle\*(C'\fR watcher makes sure the event loop |
|
|
3124 | will not sleep, and the \f(CW\*(C`ev_check\*(C'\fR watcher makes sure a callback gets |
|
|
3125 | invoked. Neither watcher alone can do that. |
2917 | .PP |
3126 | .PP |
2918 | \fIWatcher-Specific Functions and Data Members\fR |
3127 | \fIWatcher-Specific Functions and Data Members\fR |
2919 | .IX Subsection "Watcher-Specific Functions and Data Members" |
3128 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2920 | .IP "ev_prepare_init (ev_prepare *, callback)" 4 |
3129 | .IP "ev_prepare_init (ev_prepare *, callback)" 4 |
2921 | .IX Item "ev_prepare_init (ev_prepare *, callback)" |
3130 | .IX Item "ev_prepare_init (ev_prepare *, callback)" |
… | |
… | |
3032 | .Ve |
3241 | .Ve |
3033 | .PP |
3242 | .PP |
3034 | Method 4: Do not use a prepare or check watcher because the module you |
3243 | Method 4: Do not use a prepare or check watcher because the module you |
3035 | want to embed is not flexible enough to support it. Instead, you can |
3244 | want to embed is not flexible enough to support it. Instead, you can |
3036 | override their poll function. The drawback with this solution is that the |
3245 | override their poll function. The drawback with this solution is that the |
3037 | main loop is now no longer controllable by \s-1EV\s0. The \f(CW\*(C`Glib::EV\*(C'\fR module uses |
3246 | main loop is now no longer controllable by \s-1EV.\s0 The \f(CW\*(C`Glib::EV\*(C'\fR module uses |
3038 | this approach, effectively embedding \s-1EV\s0 as a client into the horrible |
3247 | this approach, effectively embedding \s-1EV\s0 as a client into the horrible |
3039 | libglib event loop. |
3248 | libglib event loop. |
3040 | .PP |
3249 | .PP |
3041 | .Vb 4 |
3250 | .Vb 4 |
3042 | \& static gint |
3251 | \& static gint |
… | |
… | |
3126 | \fIWatcher-Specific Functions and Data Members\fR |
3335 | \fIWatcher-Specific Functions and Data Members\fR |
3127 | .IX Subsection "Watcher-Specific Functions and Data Members" |
3336 | .IX Subsection "Watcher-Specific Functions and Data Members" |
3128 | .IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
3337 | .IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
3129 | .IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" |
3338 | .IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" |
3130 | .PD 0 |
3339 | .PD 0 |
3131 | .IP "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
3340 | .IP "ev_embed_set (ev_embed *, struct ev_loop *embedded_loop)" 4 |
3132 | .IX Item "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" |
3341 | .IX Item "ev_embed_set (ev_embed *, struct ev_loop *embedded_loop)" |
3133 | .PD |
3342 | .PD |
3134 | Configures the watcher to embed the given loop, which must be |
3343 | Configures the watcher to embed the given loop, which must be |
3135 | embeddable. If the callback is \f(CW0\fR, then \f(CW\*(C`ev_embed_sweep\*(C'\fR will be |
3344 | embeddable. If the callback is \f(CW0\fR, then \f(CW\*(C`ev_embed_sweep\*(C'\fR will be |
3136 | invoked automatically, otherwise it is the responsibility of the callback |
3345 | invoked automatically, otherwise it is the responsibility of the callback |
3137 | to invoke it (it will continue to be called until the sweep has been done, |
3346 | to invoke it (it will continue to be called until the sweep has been done, |
… | |
… | |
3156 | .PP |
3365 | .PP |
3157 | .Vb 3 |
3366 | .Vb 3 |
3158 | \& struct ev_loop *loop_hi = ev_default_init (0); |
3367 | \& struct ev_loop *loop_hi = ev_default_init (0); |
3159 | \& struct ev_loop *loop_lo = 0; |
3368 | \& struct ev_loop *loop_lo = 0; |
3160 | \& ev_embed embed; |
3369 | \& ev_embed embed; |
3161 | \& |
3370 | \& |
3162 | \& // see if there is a chance of getting one that works |
3371 | \& // see if there is a chance of getting one that works |
3163 | \& // (remember that a flags value of 0 means autodetection) |
3372 | \& // (remember that a flags value of 0 means autodetection) |
3164 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3373 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3165 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3374 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3166 | \& : 0; |
3375 | \& : 0; |
… | |
… | |
3182 | .PP |
3391 | .PP |
3183 | .Vb 3 |
3392 | .Vb 3 |
3184 | \& struct ev_loop *loop = ev_default_init (0); |
3393 | \& struct ev_loop *loop = ev_default_init (0); |
3185 | \& struct ev_loop *loop_socket = 0; |
3394 | \& struct ev_loop *loop_socket = 0; |
3186 | \& ev_embed embed; |
3395 | \& ev_embed embed; |
3187 | \& |
3396 | \& |
3188 | \& if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3397 | \& if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3189 | \& if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3398 | \& if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3190 | \& { |
3399 | \& { |
3191 | \& ev_embed_init (&embed, 0, loop_socket); |
3400 | \& ev_embed_init (&embed, 0, loop_socket); |
3192 | \& ev_embed_start (loop, &embed); |
3401 | \& ev_embed_start (loop, &embed); |
… | |
… | |
3200 | .ie n .SS """ev_fork"" \- the audacity to resume the event loop after a fork" |
3409 | .ie n .SS """ev_fork"" \- the audacity to resume the event loop after a fork" |
3201 | .el .SS "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
3410 | .el .SS "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
3202 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
3411 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
3203 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
3412 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
3204 | whoever is a good citizen cared to tell libev about it by calling |
3413 | whoever is a good citizen cared to tell libev about it by calling |
3205 | \&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the |
3414 | \&\f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the event loop blocks next |
3206 | event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, |
3415 | and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, and only in the child |
3207 | and only in the child after the fork. If whoever good citizen calling |
3416 | after the fork. If whoever good citizen calling \f(CW\*(C`ev_default_fork\*(C'\fR cheats |
3208 | \&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork |
3417 | and calls it in the wrong process, the fork handlers will be invoked, too, |
3209 | handlers will be invoked, too, of course. |
3418 | of course. |
3210 | .PP |
3419 | .PP |
3211 | \fIThe special problem of life after fork \- how is it possible?\fR |
3420 | \fIThe special problem of life after fork \- how is it possible?\fR |
3212 | .IX Subsection "The special problem of life after fork - how is it possible?" |
3421 | .IX Subsection "The special problem of life after fork - how is it possible?" |
3213 | .PP |
3422 | .PP |
3214 | Most uses of \f(CW\*(C`fork()\*(C'\fR consist of forking, then some simple calls to set |
3423 | Most uses of \f(CW\*(C`fork ()\*(C'\fR consist of forking, then some simple calls to set |
3215 | up/change the process environment, followed by a call to \f(CW\*(C`exec()\*(C'\fR. This |
3424 | up/change the process environment, followed by a call to \f(CW\*(C`exec()\*(C'\fR. This |
3216 | sequence should be handled by libev without any problems. |
3425 | sequence should be handled by libev without any problems. |
3217 | .PP |
3426 | .PP |
3218 | This changes when the application actually wants to do event handling |
3427 | This changes when the application actually wants to do event handling |
3219 | in the child, or both parent in child, in effect \*(L"continuing\*(R" after the |
3428 | in the child, or both parent in child, in effect \*(L"continuing\*(R" after the |
… | |
… | |
3288 | \& atexit (program_exits); |
3497 | \& atexit (program_exits); |
3289 | .Ve |
3498 | .Ve |
3290 | .ie n .SS """ev_async"" \- how to wake up an event loop" |
3499 | .ie n .SS """ev_async"" \- how to wake up an event loop" |
3291 | .el .SS "\f(CWev_async\fP \- how to wake up an event loop" |
3500 | .el .SS "\f(CWev_async\fP \- how to wake up an event loop" |
3292 | .IX Subsection "ev_async - how to wake up an event loop" |
3501 | .IX Subsection "ev_async - how to wake up an event loop" |
3293 | In general, you cannot use an \f(CW\*(C`ev_run\*(C'\fR from multiple threads or other |
3502 | In general, you cannot use an \f(CW\*(C`ev_loop\*(C'\fR from multiple threads or other |
3294 | asynchronous sources such as signal handlers (as opposed to multiple event |
3503 | asynchronous sources such as signal handlers (as opposed to multiple event |
3295 | loops \- those are of course safe to use in different threads). |
3504 | loops \- those are of course safe to use in different threads). |
3296 | .PP |
3505 | .PP |
3297 | Sometimes, however, you need to wake up an event loop you do not control, |
3506 | Sometimes, however, you need to wake up an event loop you do not control, |
3298 | for example because it belongs to another thread. This is what \f(CW\*(C`ev_async\*(C'\fR |
3507 | for example because it belongs to another thread. This is what \f(CW\*(C`ev_async\*(C'\fR |
… | |
… | |
3300 | it by calling \f(CW\*(C`ev_async_send\*(C'\fR, which is thread\- and signal safe. |
3509 | it by calling \f(CW\*(C`ev_async_send\*(C'\fR, which is thread\- and signal safe. |
3301 | .PP |
3510 | .PP |
3302 | This functionality is very similar to \f(CW\*(C`ev_signal\*(C'\fR watchers, as signals, |
3511 | This functionality is very similar to \f(CW\*(C`ev_signal\*(C'\fR watchers, as signals, |
3303 | too, are asynchronous in nature, and signals, too, will be compressed |
3512 | too, are asynchronous in nature, and signals, too, will be compressed |
3304 | (i.e. the number of callback invocations may be less than the number of |
3513 | (i.e. the number of callback invocations may be less than the number of |
3305 | \&\f(CW\*(C`ev_async_sent\*(C'\fR calls). |
3514 | \&\f(CW\*(C`ev_async_send\*(C'\fR calls). In fact, you could use signal watchers as a kind |
3306 | .PP |
3515 | of \*(L"global async watchers\*(R" by using a watcher on an otherwise unused |
3307 | Unlike \f(CW\*(C`ev_signal\*(C'\fR watchers, \f(CW\*(C`ev_async\*(C'\fR works with any event loop, not |
3516 | signal, and \f(CW\*(C`ev_feed_signal\*(C'\fR to signal this watcher from another thread, |
3308 | just the default loop. |
3517 | even without knowing which loop owns the signal. |
3309 | .PP |
3518 | .PP |
3310 | \fIQueueing\fR |
3519 | \fIQueueing\fR |
3311 | .IX Subsection "Queueing" |
3520 | .IX Subsection "Queueing" |
3312 | .PP |
3521 | .PP |
3313 | \&\f(CW\*(C`ev_async\*(C'\fR does not support queueing of data in any way. The reason |
3522 | \&\f(CW\*(C`ev_async\*(C'\fR does not support queueing of data in any way. The reason |
… | |
… | |
3400 | kind. There is a \f(CW\*(C`ev_async_set\*(C'\fR macro, but using it is utterly pointless, |
3609 | kind. There is a \f(CW\*(C`ev_async_set\*(C'\fR macro, but using it is utterly pointless, |
3401 | trust me. |
3610 | trust me. |
3402 | .IP "ev_async_send (loop, ev_async *)" 4 |
3611 | .IP "ev_async_send (loop, ev_async *)" 4 |
3403 | .IX Item "ev_async_send (loop, ev_async *)" |
3612 | .IX Item "ev_async_send (loop, ev_async *)" |
3404 | Sends/signals/activates the given \f(CW\*(C`ev_async\*(C'\fR watcher, that is, feeds |
3613 | Sends/signals/activates the given \f(CW\*(C`ev_async\*(C'\fR watcher, that is, feeds |
3405 | an \f(CW\*(C`EV_ASYNC\*(C'\fR event on the watcher into the event loop. Unlike |
3614 | an \f(CW\*(C`EV_ASYNC\*(C'\fR event on the watcher into the event loop, and instantly |
|
|
3615 | returns. |
|
|
3616 | .Sp |
3406 | \&\f(CW\*(C`ev_feed_event\*(C'\fR, this call is safe to do from other threads, signal or |
3617 | Unlike \f(CW\*(C`ev_feed_event\*(C'\fR, this call is safe to do from other threads, |
3407 | similar contexts (see the discussion of \f(CW\*(C`EV_ATOMIC_T\*(C'\fR in the embedding |
3618 | signal or similar contexts (see the discussion of \f(CW\*(C`EV_ATOMIC_T\*(C'\fR in the |
3408 | section below on what exactly this means). |
3619 | embedding section below on what exactly this means). |
3409 | .Sp |
3620 | .Sp |
3410 | Note that, as with other watchers in libev, multiple events might get |
3621 | Note that, as with other watchers in libev, multiple events might get |
3411 | compressed into a single callback invocation (another way to look at this |
3622 | compressed into a single callback invocation (another way to look at |
3412 | is that \f(CW\*(C`ev_async\*(C'\fR watchers are level-triggered, set on \f(CW\*(C`ev_async_send\*(C'\fR, |
3623 | this is that \f(CW\*(C`ev_async\*(C'\fR watchers are level-triggered: they are set on |
3413 | reset when the event loop detects that). |
3624 | \&\f(CW\*(C`ev_async_send\*(C'\fR, reset when the event loop detects that). |
3414 | .Sp |
3625 | .Sp |
3415 | This call incurs the overhead of a system call only once per event loop |
3626 | This call incurs the overhead of at most one extra system call per event |
3416 | iteration, so while the overhead might be noticeable, it doesn't apply to |
3627 | loop iteration, if the event loop is blocked, and no syscall at all if |
3417 | repeated calls to \f(CW\*(C`ev_async_send\*(C'\fR for the same event loop. |
3628 | the event loop (or your program) is processing events. That means that |
|
|
3629 | repeated calls are basically free (there is no need to avoid calls for |
|
|
3630 | performance reasons) and that the overhead becomes smaller (typically |
|
|
3631 | zero) under load. |
3418 | .IP "bool = ev_async_pending (ev_async *)" 4 |
3632 | .IP "bool = ev_async_pending (ev_async *)" 4 |
3419 | .IX Item "bool = ev_async_pending (ev_async *)" |
3633 | .IX Item "bool = ev_async_pending (ev_async *)" |
3420 | Returns a non-zero value when \f(CW\*(C`ev_async_send\*(C'\fR has been called on the |
3634 | Returns a non-zero value when \f(CW\*(C`ev_async_send\*(C'\fR has been called on the |
3421 | watcher but the event has not yet been processed (or even noted) by the |
3635 | watcher but the event has not yet been processed (or even noted) by the |
3422 | event loop. |
3636 | event loop. |
… | |
… | |
3454 | \&\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 |
3668 | \&\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 |
3455 | value passed to \f(CW\*(C`ev_once\*(C'\fR. Note that it is possible to receive \fIboth\fR |
3669 | value passed to \f(CW\*(C`ev_once\*(C'\fR. Note that it is possible to receive \fIboth\fR |
3456 | a timeout and an io event at the same time \- you probably should give io |
3670 | a timeout and an io event at the same time \- you probably should give io |
3457 | events precedence. |
3671 | events precedence. |
3458 | .Sp |
3672 | .Sp |
3459 | Example: wait up to ten seconds for data to appear on \s-1STDIN_FILENO\s0. |
3673 | Example: wait up to ten seconds for data to appear on \s-1STDIN_FILENO.\s0 |
3460 | .Sp |
3674 | .Sp |
3461 | .Vb 7 |
3675 | .Vb 7 |
3462 | \& static void stdin_ready (int revents, void *arg) |
3676 | \& static void stdin_ready (int revents, void *arg) |
3463 | \& { |
3677 | \& { |
3464 | \& if (revents & EV_READ) |
3678 | \& if (revents & EV_READ) |
… | |
… | |
3470 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3684 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3471 | .Ve |
3685 | .Ve |
3472 | .IP "ev_feed_fd_event (loop, int fd, int revents)" 4 |
3686 | .IP "ev_feed_fd_event (loop, int fd, int revents)" 4 |
3473 | .IX Item "ev_feed_fd_event (loop, int fd, int revents)" |
3687 | .IX Item "ev_feed_fd_event (loop, int fd, int revents)" |
3474 | Feed an event on the given fd, as if a file descriptor backend detected |
3688 | Feed an event on the given fd, as if a file descriptor backend detected |
3475 | the given events it. |
3689 | the given events. |
3476 | .IP "ev_feed_signal_event (loop, int signum)" 4 |
3690 | .IP "ev_feed_signal_event (loop, int signum)" 4 |
3477 | .IX Item "ev_feed_signal_event (loop, int signum)" |
3691 | .IX Item "ev_feed_signal_event (loop, int signum)" |
3478 | Feed an event as if the given signal occurred (\f(CW\*(C`loop\*(C'\fR must be the default |
3692 | Feed an event as if the given signal occurred. See also \f(CW\*(C`ev_feed_signal\*(C'\fR, |
3479 | loop!). |
3693 | which is async-safe. |
|
|
3694 | .SH "COMMON OR USEFUL IDIOMS (OR BOTH)" |
|
|
3695 | .IX Header "COMMON OR USEFUL IDIOMS (OR BOTH)" |
|
|
3696 | This section explains some common idioms that are not immediately |
|
|
3697 | obvious. Note that examples are sprinkled over the whole manual, and this |
|
|
3698 | section only contains stuff that wouldn't fit anywhere else. |
|
|
3699 | .SS "\s-1ASSOCIATING CUSTOM DATA WITH A WATCHER\s0" |
|
|
3700 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
|
|
3701 | Each watcher has, by default, a \f(CW\*(C`void *data\*(C'\fR member that you can read |
|
|
3702 | or modify at any time: libev will completely ignore it. This can be used |
|
|
3703 | to associate arbitrary data with your watcher. If you need more data and |
|
|
3704 | don't want to allocate memory separately and store a pointer to it in that |
|
|
3705 | data member, you can also \*(L"subclass\*(R" the watcher type and provide your own |
|
|
3706 | data: |
|
|
3707 | .PP |
|
|
3708 | .Vb 7 |
|
|
3709 | \& struct my_io |
|
|
3710 | \& { |
|
|
3711 | \& ev_io io; |
|
|
3712 | \& int otherfd; |
|
|
3713 | \& void *somedata; |
|
|
3714 | \& struct whatever *mostinteresting; |
|
|
3715 | \& }; |
|
|
3716 | \& |
|
|
3717 | \& ... |
|
|
3718 | \& struct my_io w; |
|
|
3719 | \& ev_io_init (&w.io, my_cb, fd, EV_READ); |
|
|
3720 | .Ve |
|
|
3721 | .PP |
|
|
3722 | And since your callback will be called with a pointer to the watcher, you |
|
|
3723 | can cast it back to your own type: |
|
|
3724 | .PP |
|
|
3725 | .Vb 5 |
|
|
3726 | \& static void my_cb (struct ev_loop *loop, ev_io *w_, int revents) |
|
|
3727 | \& { |
|
|
3728 | \& struct my_io *w = (struct my_io *)w_; |
|
|
3729 | \& ... |
|
|
3730 | \& } |
|
|
3731 | .Ve |
|
|
3732 | .PP |
|
|
3733 | More interesting and less C\-conformant ways of casting your callback |
|
|
3734 | function type instead have been omitted. |
|
|
3735 | .SS "\s-1BUILDING YOUR OWN COMPOSITE WATCHERS\s0" |
|
|
3736 | .IX Subsection "BUILDING YOUR OWN COMPOSITE WATCHERS" |
|
|
3737 | Another common scenario is to use some data structure with multiple |
|
|
3738 | embedded watchers, in effect creating your own watcher that combines |
|
|
3739 | multiple libev event sources into one \*(L"super-watcher\*(R": |
|
|
3740 | .PP |
|
|
3741 | .Vb 6 |
|
|
3742 | \& struct my_biggy |
|
|
3743 | \& { |
|
|
3744 | \& int some_data; |
|
|
3745 | \& ev_timer t1; |
|
|
3746 | \& ev_timer t2; |
|
|
3747 | \& } |
|
|
3748 | .Ve |
|
|
3749 | .PP |
|
|
3750 | In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more |
|
|
3751 | complicated: Either you store the address of your \f(CW\*(C`my_biggy\*(C'\fR struct in |
|
|
3752 | the \f(CW\*(C`data\*(C'\fR member of the watcher (for woozies or \*(C+ coders), or you need |
|
|
3753 | to use some pointer arithmetic using \f(CW\*(C`offsetof\*(C'\fR inside your watchers (for |
|
|
3754 | real programmers): |
|
|
3755 | .PP |
|
|
3756 | .Vb 1 |
|
|
3757 | \& #include <stddef.h> |
|
|
3758 | \& |
|
|
3759 | \& static void |
|
|
3760 | \& t1_cb (EV_P_ ev_timer *w, int revents) |
|
|
3761 | \& { |
|
|
3762 | \& struct my_biggy big = (struct my_biggy *) |
|
|
3763 | \& (((char *)w) \- offsetof (struct my_biggy, t1)); |
|
|
3764 | \& } |
|
|
3765 | \& |
|
|
3766 | \& static void |
|
|
3767 | \& t2_cb (EV_P_ ev_timer *w, int revents) |
|
|
3768 | \& { |
|
|
3769 | \& struct my_biggy big = (struct my_biggy *) |
|
|
3770 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
|
|
3771 | \& } |
|
|
3772 | .Ve |
|
|
3773 | .SS "\s-1AVOIDING FINISHING BEFORE RETURNING\s0" |
|
|
3774 | .IX Subsection "AVOIDING FINISHING BEFORE RETURNING" |
|
|
3775 | Often you have structures like this in event-based programs: |
|
|
3776 | .PP |
|
|
3777 | .Vb 4 |
|
|
3778 | \& callback () |
|
|
3779 | \& { |
|
|
3780 | \& free (request); |
|
|
3781 | \& } |
|
|
3782 | \& |
|
|
3783 | \& request = start_new_request (..., callback); |
|
|
3784 | .Ve |
|
|
3785 | .PP |
|
|
3786 | The intent is to start some \*(L"lengthy\*(R" operation. The \f(CW\*(C`request\*(C'\fR could be |
|
|
3787 | used to cancel the operation, or do other things with it. |
|
|
3788 | .PP |
|
|
3789 | It's not uncommon to have code paths in \f(CW\*(C`start_new_request\*(C'\fR that |
|
|
3790 | immediately invoke the callback, for example, to report errors. Or you add |
|
|
3791 | some caching layer that finds that it can skip the lengthy aspects of the |
|
|
3792 | operation and simply invoke the callback with the result. |
|
|
3793 | .PP |
|
|
3794 | The problem here is that this will happen \fIbefore\fR \f(CW\*(C`start_new_request\*(C'\fR |
|
|
3795 | has returned, so \f(CW\*(C`request\*(C'\fR is not set. |
|
|
3796 | .PP |
|
|
3797 | Even if you pass the request by some safer means to the callback, you |
|
|
3798 | might want to do something to the request after starting it, such as |
|
|
3799 | canceling it, which probably isn't working so well when the callback has |
|
|
3800 | already been invoked. |
|
|
3801 | .PP |
|
|
3802 | A common way around all these issues is to make sure that |
|
|
3803 | \&\f(CW\*(C`start_new_request\*(C'\fR \fIalways\fR returns before the callback is invoked. If |
|
|
3804 | \&\f(CW\*(C`start_new_request\*(C'\fR immediately knows the result, it can artificially |
|
|
3805 | delay invoking the callback by using a \f(CW\*(C`prepare\*(C'\fR or \f(CW\*(C`idle\*(C'\fR watcher for |
|
|
3806 | example, or more sneakily, by reusing an existing (stopped) watcher and |
|
|
3807 | pushing it into the pending queue: |
|
|
3808 | .PP |
|
|
3809 | .Vb 2 |
|
|
3810 | \& ev_set_cb (watcher, callback); |
|
|
3811 | \& ev_feed_event (EV_A_ watcher, 0); |
|
|
3812 | .Ve |
|
|
3813 | .PP |
|
|
3814 | This way, \f(CW\*(C`start_new_request\*(C'\fR can safely return before the callback is |
|
|
3815 | invoked, while not delaying callback invocation too much. |
|
|
3816 | .SS "\s-1MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS\s0" |
|
|
3817 | .IX Subsection "MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS" |
|
|
3818 | Often (especially in \s-1GUI\s0 toolkits) there are places where you have |
|
|
3819 | \&\fImodal\fR interaction, which is most easily implemented by recursively |
|
|
3820 | invoking \f(CW\*(C`ev_run\*(C'\fR. |
|
|
3821 | .PP |
|
|
3822 | This brings the problem of exiting \- a callback might want to finish the |
|
|
3823 | main \f(CW\*(C`ev_run\*(C'\fR call, but not the nested one (e.g. user clicked \*(L"Quit\*(R", but |
|
|
3824 | a modal \*(L"Are you sure?\*(R" dialog is still waiting), or just the nested one |
|
|
3825 | and not the main one (e.g. user clocked \*(L"Ok\*(R" in a modal dialog), or some |
|
|
3826 | other combination: In these cases, a simple \f(CW\*(C`ev_break\*(C'\fR will not work. |
|
|
3827 | .PP |
|
|
3828 | The solution is to maintain \*(L"break this loop\*(R" variable for each \f(CW\*(C`ev_run\*(C'\fR |
|
|
3829 | invocation, and use a loop around \f(CW\*(C`ev_run\*(C'\fR until the condition is |
|
|
3830 | triggered, using \f(CW\*(C`EVRUN_ONCE\*(C'\fR: |
|
|
3831 | .PP |
|
|
3832 | .Vb 2 |
|
|
3833 | \& // main loop |
|
|
3834 | \& int exit_main_loop = 0; |
|
|
3835 | \& |
|
|
3836 | \& while (!exit_main_loop) |
|
|
3837 | \& ev_run (EV_DEFAULT_ EVRUN_ONCE); |
|
|
3838 | \& |
|
|
3839 | \& // in a modal watcher |
|
|
3840 | \& int exit_nested_loop = 0; |
|
|
3841 | \& |
|
|
3842 | \& while (!exit_nested_loop) |
|
|
3843 | \& ev_run (EV_A_ EVRUN_ONCE); |
|
|
3844 | .Ve |
|
|
3845 | .PP |
|
|
3846 | To exit from any of these loops, just set the corresponding exit variable: |
|
|
3847 | .PP |
|
|
3848 | .Vb 2 |
|
|
3849 | \& // exit modal loop |
|
|
3850 | \& exit_nested_loop = 1; |
|
|
3851 | \& |
|
|
3852 | \& // exit main program, after modal loop is finished |
|
|
3853 | \& exit_main_loop = 1; |
|
|
3854 | \& |
|
|
3855 | \& // exit both |
|
|
3856 | \& exit_main_loop = exit_nested_loop = 1; |
|
|
3857 | .Ve |
|
|
3858 | .SS "\s-1THREAD LOCKING EXAMPLE\s0" |
|
|
3859 | .IX Subsection "THREAD LOCKING EXAMPLE" |
|
|
3860 | Here is a fictitious example of how to run an event loop in a different |
|
|
3861 | thread from where callbacks are being invoked and watchers are |
|
|
3862 | created/added/removed. |
|
|
3863 | .PP |
|
|
3864 | For a real-world example, see the \f(CW\*(C`EV::Loop::Async\*(C'\fR perl module, |
|
|
3865 | which uses exactly this technique (which is suited for many high-level |
|
|
3866 | languages). |
|
|
3867 | .PP |
|
|
3868 | The example uses a pthread mutex to protect the loop data, a condition |
|
|
3869 | variable to wait for callback invocations, an async watcher to notify the |
|
|
3870 | event loop thread and an unspecified mechanism to wake up the main thread. |
|
|
3871 | .PP |
|
|
3872 | First, you need to associate some data with the event loop: |
|
|
3873 | .PP |
|
|
3874 | .Vb 6 |
|
|
3875 | \& typedef struct { |
|
|
3876 | \& mutex_t lock; /* global loop lock */ |
|
|
3877 | \& ev_async async_w; |
|
|
3878 | \& thread_t tid; |
|
|
3879 | \& cond_t invoke_cv; |
|
|
3880 | \& } userdata; |
|
|
3881 | \& |
|
|
3882 | \& void prepare_loop (EV_P) |
|
|
3883 | \& { |
|
|
3884 | \& // for simplicity, we use a static userdata struct. |
|
|
3885 | \& static userdata u; |
|
|
3886 | \& |
|
|
3887 | \& ev_async_init (&u\->async_w, async_cb); |
|
|
3888 | \& ev_async_start (EV_A_ &u\->async_w); |
|
|
3889 | \& |
|
|
3890 | \& pthread_mutex_init (&u\->lock, 0); |
|
|
3891 | \& pthread_cond_init (&u\->invoke_cv, 0); |
|
|
3892 | \& |
|
|
3893 | \& // now associate this with the loop |
|
|
3894 | \& ev_set_userdata (EV_A_ u); |
|
|
3895 | \& ev_set_invoke_pending_cb (EV_A_ l_invoke); |
|
|
3896 | \& ev_set_loop_release_cb (EV_A_ l_release, l_acquire); |
|
|
3897 | \& |
|
|
3898 | \& // then create the thread running ev_run |
|
|
3899 | \& pthread_create (&u\->tid, 0, l_run, EV_A); |
|
|
3900 | \& } |
|
|
3901 | .Ve |
|
|
3902 | .PP |
|
|
3903 | The callback for the \f(CW\*(C`ev_async\*(C'\fR watcher does nothing: the watcher is used |
|
|
3904 | solely to wake up the event loop so it takes notice of any new watchers |
|
|
3905 | that might have been added: |
|
|
3906 | .PP |
|
|
3907 | .Vb 5 |
|
|
3908 | \& static void |
|
|
3909 | \& async_cb (EV_P_ ev_async *w, int revents) |
|
|
3910 | \& { |
|
|
3911 | \& // just used for the side effects |
|
|
3912 | \& } |
|
|
3913 | .Ve |
|
|
3914 | .PP |
|
|
3915 | The \f(CW\*(C`l_release\*(C'\fR and \f(CW\*(C`l_acquire\*(C'\fR callbacks simply unlock/lock the mutex |
|
|
3916 | protecting the loop data, respectively. |
|
|
3917 | .PP |
|
|
3918 | .Vb 6 |
|
|
3919 | \& static void |
|
|
3920 | \& l_release (EV_P) |
|
|
3921 | \& { |
|
|
3922 | \& userdata *u = ev_userdata (EV_A); |
|
|
3923 | \& pthread_mutex_unlock (&u\->lock); |
|
|
3924 | \& } |
|
|
3925 | \& |
|
|
3926 | \& static void |
|
|
3927 | \& l_acquire (EV_P) |
|
|
3928 | \& { |
|
|
3929 | \& userdata *u = ev_userdata (EV_A); |
|
|
3930 | \& pthread_mutex_lock (&u\->lock); |
|
|
3931 | \& } |
|
|
3932 | .Ve |
|
|
3933 | .PP |
|
|
3934 | The event loop thread first acquires the mutex, and then jumps straight |
|
|
3935 | into \f(CW\*(C`ev_run\*(C'\fR: |
|
|
3936 | .PP |
|
|
3937 | .Vb 4 |
|
|
3938 | \& void * |
|
|
3939 | \& l_run (void *thr_arg) |
|
|
3940 | \& { |
|
|
3941 | \& struct ev_loop *loop = (struct ev_loop *)thr_arg; |
|
|
3942 | \& |
|
|
3943 | \& l_acquire (EV_A); |
|
|
3944 | \& pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
|
|
3945 | \& ev_run (EV_A_ 0); |
|
|
3946 | \& l_release (EV_A); |
|
|
3947 | \& |
|
|
3948 | \& return 0; |
|
|
3949 | \& } |
|
|
3950 | .Ve |
|
|
3951 | .PP |
|
|
3952 | Instead of invoking all pending watchers, the \f(CW\*(C`l_invoke\*(C'\fR callback will |
|
|
3953 | signal the main thread via some unspecified mechanism (signals? pipe |
|
|
3954 | writes? \f(CW\*(C`Async::Interrupt\*(C'\fR?) and then waits until all pending watchers |
|
|
3955 | have been called (in a while loop because a) spurious wakeups are possible |
|
|
3956 | and b) skipping inter-thread-communication when there are no pending |
|
|
3957 | watchers is very beneficial): |
|
|
3958 | .PP |
|
|
3959 | .Vb 4 |
|
|
3960 | \& static void |
|
|
3961 | \& l_invoke (EV_P) |
|
|
3962 | \& { |
|
|
3963 | \& userdata *u = ev_userdata (EV_A); |
|
|
3964 | \& |
|
|
3965 | \& while (ev_pending_count (EV_A)) |
|
|
3966 | \& { |
|
|
3967 | \& wake_up_other_thread_in_some_magic_or_not_so_magic_way (); |
|
|
3968 | \& pthread_cond_wait (&u\->invoke_cv, &u\->lock); |
|
|
3969 | \& } |
|
|
3970 | \& } |
|
|
3971 | .Ve |
|
|
3972 | .PP |
|
|
3973 | Now, whenever the main thread gets told to invoke pending watchers, it |
|
|
3974 | will grab the lock, call \f(CW\*(C`ev_invoke_pending\*(C'\fR and then signal the loop |
|
|
3975 | thread to continue: |
|
|
3976 | .PP |
|
|
3977 | .Vb 4 |
|
|
3978 | \& static void |
|
|
3979 | \& real_invoke_pending (EV_P) |
|
|
3980 | \& { |
|
|
3981 | \& userdata *u = ev_userdata (EV_A); |
|
|
3982 | \& |
|
|
3983 | \& pthread_mutex_lock (&u\->lock); |
|
|
3984 | \& ev_invoke_pending (EV_A); |
|
|
3985 | \& pthread_cond_signal (&u\->invoke_cv); |
|
|
3986 | \& pthread_mutex_unlock (&u\->lock); |
|
|
3987 | \& } |
|
|
3988 | .Ve |
|
|
3989 | .PP |
|
|
3990 | Whenever you want to start/stop a watcher or do other modifications to an |
|
|
3991 | event loop, you will now have to lock: |
|
|
3992 | .PP |
|
|
3993 | .Vb 2 |
|
|
3994 | \& ev_timer timeout_watcher; |
|
|
3995 | \& userdata *u = ev_userdata (EV_A); |
|
|
3996 | \& |
|
|
3997 | \& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
|
|
3998 | \& |
|
|
3999 | \& pthread_mutex_lock (&u\->lock); |
|
|
4000 | \& ev_timer_start (EV_A_ &timeout_watcher); |
|
|
4001 | \& ev_async_send (EV_A_ &u\->async_w); |
|
|
4002 | \& pthread_mutex_unlock (&u\->lock); |
|
|
4003 | .Ve |
|
|
4004 | .PP |
|
|
4005 | Note that sending the \f(CW\*(C`ev_async\*(C'\fR watcher is required because otherwise |
|
|
4006 | an event loop currently blocking in the kernel will have no knowledge |
|
|
4007 | about the newly added timer. By waking up the loop it will pick up any new |
|
|
4008 | watchers in the next event loop iteration. |
|
|
4009 | .SS "\s-1THREADS, COROUTINES, CONTINUATIONS, QUEUES... INSTEAD OF CALLBACKS\s0" |
|
|
4010 | .IX Subsection "THREADS, COROUTINES, CONTINUATIONS, QUEUES... INSTEAD OF CALLBACKS" |
|
|
4011 | While the overhead of a callback that e.g. schedules a thread is small, it |
|
|
4012 | is still an overhead. If you embed libev, and your main usage is with some |
|
|
4013 | kind of threads or coroutines, you might want to customise libev so that |
|
|
4014 | doesn't need callbacks anymore. |
|
|
4015 | .PP |
|
|
4016 | Imagine you have coroutines that you can switch to using a function |
|
|
4017 | \&\f(CW\*(C`switch_to (coro)\*(C'\fR, that libev runs in a coroutine called \f(CW\*(C`libev_coro\*(C'\fR |
|
|
4018 | and that due to some magic, the currently active coroutine is stored in a |
|
|
4019 | global called \f(CW\*(C`current_coro\*(C'\fR. Then you can build your own \*(L"wait for libev |
|
|
4020 | event\*(R" primitive by changing \f(CW\*(C`EV_CB_DECLARE\*(C'\fR and \f(CW\*(C`EV_CB_INVOKE\*(C'\fR (note |
|
|
4021 | the differing \f(CW\*(C`;\*(C'\fR conventions): |
|
|
4022 | .PP |
|
|
4023 | .Vb 2 |
|
|
4024 | \& #define EV_CB_DECLARE(type) struct my_coro *cb; |
|
|
4025 | \& #define EV_CB_INVOKE(watcher) switch_to ((watcher)\->cb) |
|
|
4026 | .Ve |
|
|
4027 | .PP |
|
|
4028 | That means instead of having a C callback function, you store the |
|
|
4029 | coroutine to switch to in each watcher, and instead of having libev call |
|
|
4030 | your callback, you instead have it switch to that coroutine. |
|
|
4031 | .PP |
|
|
4032 | A coroutine might now wait for an event with a function called |
|
|
4033 | \&\f(CW\*(C`wait_for_event\*(C'\fR. (the watcher needs to be started, as always, but it doesn't |
|
|
4034 | matter when, or whether the watcher is active or not when this function is |
|
|
4035 | called): |
|
|
4036 | .PP |
|
|
4037 | .Vb 6 |
|
|
4038 | \& void |
|
|
4039 | \& wait_for_event (ev_watcher *w) |
|
|
4040 | \& { |
|
|
4041 | \& ev_set_cb (w, current_coro); |
|
|
4042 | \& switch_to (libev_coro); |
|
|
4043 | \& } |
|
|
4044 | .Ve |
|
|
4045 | .PP |
|
|
4046 | That basically suspends the coroutine inside \f(CW\*(C`wait_for_event\*(C'\fR and |
|
|
4047 | continues the libev coroutine, which, when appropriate, switches back to |
|
|
4048 | this or any other coroutine. |
|
|
4049 | .PP |
|
|
4050 | You can do similar tricks if you have, say, threads with an event queue \- |
|
|
4051 | instead of storing a coroutine, you store the queue object and instead of |
|
|
4052 | switching to a coroutine, you push the watcher onto the queue and notify |
|
|
4053 | any waiters. |
|
|
4054 | .PP |
|
|
4055 | To embed libev, see \*(L"\s-1EMBEDDING\*(R"\s0, but in short, it's easiest to create two |
|
|
4056 | files, \fImy_ev.h\fR and \fImy_ev.c\fR that include the respective libev files: |
|
|
4057 | .PP |
|
|
4058 | .Vb 4 |
|
|
4059 | \& // my_ev.h |
|
|
4060 | \& #define EV_CB_DECLARE(type) struct my_coro *cb; |
|
|
4061 | \& #define EV_CB_INVOKE(watcher) switch_to ((watcher)\->cb) |
|
|
4062 | \& #include "../libev/ev.h" |
|
|
4063 | \& |
|
|
4064 | \& // my_ev.c |
|
|
4065 | \& #define EV_H "my_ev.h" |
|
|
4066 | \& #include "../libev/ev.c" |
|
|
4067 | .Ve |
|
|
4068 | .PP |
|
|
4069 | And then use \fImy_ev.h\fR when you would normally use \fIev.h\fR, and compile |
|
|
4070 | \&\fImy_ev.c\fR into your project. When properly specifying include paths, you |
|
|
4071 | can even use \fIev.h\fR as header file name directly. |
3480 | .SH "LIBEVENT EMULATION" |
4072 | .SH "LIBEVENT EMULATION" |
3481 | .IX Header "LIBEVENT EMULATION" |
4073 | .IX Header "LIBEVENT EMULATION" |
3482 | Libev offers a compatibility emulation layer for libevent. It cannot |
4074 | Libev offers a compatibility emulation layer for libevent. It cannot |
3483 | emulate the internals of libevent, so here are some usage hints: |
4075 | emulate the internals of libevent, so here are some usage hints: |
|
|
4076 | .IP "\(bu" 4 |
|
|
4077 | Only the libevent\-1.4.1\-beta \s-1API\s0 is being emulated. |
|
|
4078 | .Sp |
|
|
4079 | This was the newest libevent version available when libev was implemented, |
|
|
4080 | and is still mostly unchanged in 2010. |
3484 | .IP "\(bu" 4 |
4081 | .IP "\(bu" 4 |
3485 | Use it by including <event.h>, as usual. |
4082 | Use it by including <event.h>, as usual. |
3486 | .IP "\(bu" 4 |
4083 | .IP "\(bu" 4 |
3487 | The following members are fully supported: ev_base, ev_callback, |
4084 | The following members are fully supported: ev_base, ev_callback, |
3488 | ev_arg, ev_fd, ev_res, ev_events. |
4085 | ev_arg, ev_fd, ev_res, ev_events. |
… | |
… | |
3494 | Priorities are not currently supported. Initialising priorities |
4091 | Priorities are not currently supported. Initialising priorities |
3495 | will fail and all watchers will have the same priority, even though there |
4092 | will fail and all watchers will have the same priority, even though there |
3496 | is an ev_pri field. |
4093 | is an ev_pri field. |
3497 | .IP "\(bu" 4 |
4094 | .IP "\(bu" 4 |
3498 | In libevent, the last base created gets the signals, in libev, the |
4095 | In libevent, the last base created gets the signals, in libev, the |
3499 | first base created (== the default loop) gets the signals. |
4096 | base that registered the signal gets the signals. |
3500 | .IP "\(bu" 4 |
4097 | .IP "\(bu" 4 |
3501 | Other members are not supported. |
4098 | Other members are not supported. |
3502 | .IP "\(bu" 4 |
4099 | .IP "\(bu" 4 |
3503 | The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need |
4100 | The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need |
3504 | to use the libev header file and library. |
4101 | to use the libev header file and library. |
3505 | .SH "\*(C+ SUPPORT" |
4102 | .SH "\*(C+ SUPPORT" |
3506 | .IX Header " SUPPORT" |
4103 | .IX Header " SUPPORT" |
|
|
4104 | .SS "C \s-1API\s0" |
|
|
4105 | .IX Subsection "C API" |
|
|
4106 | The normal C \s-1API\s0 should work fine when used from \*(C+: both ev.h and the |
|
|
4107 | libev sources can be compiled as \*(C+. Therefore, code that uses the C \s-1API\s0 |
|
|
4108 | will work fine. |
|
|
4109 | .PP |
|
|
4110 | Proper exception specifications might have to be added to callbacks passed |
|
|
4111 | to libev: exceptions may be thrown only from watcher callbacks, all |
|
|
4112 | other callbacks (allocator, syserr, loop acquire/release and periodic |
|
|
4113 | reschedule callbacks) must not throw exceptions, and might need a \f(CW\*(C`throw |
|
|
4114 | ()\*(C'\fR specification. If you have code that needs to be compiled as both C |
|
|
4115 | and \*(C+ you can use the \f(CW\*(C`EV_THROW\*(C'\fR macro for this: |
|
|
4116 | .PP |
|
|
4117 | .Vb 6 |
|
|
4118 | \& static void |
|
|
4119 | \& fatal_error (const char *msg) EV_THROW |
|
|
4120 | \& { |
|
|
4121 | \& perror (msg); |
|
|
4122 | \& abort (); |
|
|
4123 | \& } |
|
|
4124 | \& |
|
|
4125 | \& ... |
|
|
4126 | \& ev_set_syserr_cb (fatal_error); |
|
|
4127 | .Ve |
|
|
4128 | .PP |
|
|
4129 | The only \s-1API\s0 functions that can currently throw exceptions are \f(CW\*(C`ev_run\*(C'\fR, |
|
|
4130 | \&\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 |
|
|
4131 | because it runs cleanup watchers). |
|
|
4132 | .PP |
|
|
4133 | Throwing exceptions in watcher callbacks is only supported if libev itself |
|
|
4134 | is compiled with a \*(C+ compiler or your C and \*(C+ environments allow |
|
|
4135 | throwing exceptions through C libraries (most do). |
|
|
4136 | .SS "\*(C+ \s-1API\s0" |
|
|
4137 | .IX Subsection " API" |
3507 | Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow |
4138 | Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow |
3508 | you to use some convenience methods to start/stop watchers and also change |
4139 | you to use some convenience methods to start/stop watchers and also change |
3509 | the callback model to a model using method callbacks on objects. |
4140 | the callback model to a model using method callbacks on objects. |
3510 | .PP |
4141 | .PP |
3511 | To use it, |
4142 | To use it, |
… | |
… | |
3522 | Care has been taken to keep the overhead low. The only data member the \*(C+ |
4153 | Care has been taken to keep the overhead low. The only data member the \*(C+ |
3523 | classes add (compared to plain C\-style watchers) is the event loop pointer |
4154 | classes add (compared to plain C\-style watchers) is the event loop pointer |
3524 | that the watcher is associated with (or no additional members at all if |
4155 | that the watcher is associated with (or no additional members at all if |
3525 | you disable \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR when embedding libev). |
4156 | you disable \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR when embedding libev). |
3526 | .PP |
4157 | .PP |
3527 | Currently, functions, and static and non-static member functions can be |
4158 | Currently, functions, static and non-static member functions and classes |
3528 | used as callbacks. Other types should be easy to add as long as they only |
4159 | with \f(CW\*(C`operator ()\*(C'\fR can be used as callbacks. Other types should be easy |
3529 | need one additional pointer for context. If you need support for other |
4160 | to add as long as they only need one additional pointer for context. If |
3530 | types of functors please contact the author (preferably after implementing |
4161 | you need support for other types of functors please contact the author |
3531 | it). |
4162 | (preferably after implementing it). |
|
|
4163 | .PP |
|
|
4164 | For all this to work, your \*(C+ compiler either has to use the same calling |
|
|
4165 | conventions as your C compiler (for static member functions), or you have |
|
|
4166 | to embed libev and compile libev itself as \*(C+. |
3532 | .PP |
4167 | .PP |
3533 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
4168 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
3534 | .ie n .IP """ev::READ"", ""ev::WRITE"" etc." 4 |
4169 | .ie n .IP """ev::READ"", ""ev::WRITE"" etc." 4 |
3535 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
4170 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
3536 | .IX Item "ev::READ, ev::WRITE etc." |
4171 | .IX Item "ev::READ, ev::WRITE etc." |
… | |
… | |
3544 | .el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4 |
4179 | .el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4 |
3545 | .IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc." |
4180 | .IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc." |
3546 | For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of |
4181 | For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of |
3547 | the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR |
4182 | the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR |
3548 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
4183 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
3549 | defines by many implementations. |
4184 | defined by many implementations. |
3550 | .Sp |
4185 | .Sp |
3551 | All of those classes have these methods: |
4186 | All of those classes have these methods: |
3552 | .RS 4 |
4187 | .RS 4 |
3553 | .IP "ev::TYPE::TYPE ()" 4 |
4188 | .IP "ev::TYPE::TYPE ()" 4 |
3554 | .IX Item "ev::TYPE::TYPE ()" |
4189 | .IX Item "ev::TYPE::TYPE ()" |
… | |
… | |
3617 | \& void operator() (ev::io &w, int revents) |
4252 | \& void operator() (ev::io &w, int revents) |
3618 | \& { |
4253 | \& { |
3619 | \& ... |
4254 | \& ... |
3620 | \& } |
4255 | \& } |
3621 | \& } |
4256 | \& } |
3622 | \& |
4257 | \& |
3623 | \& myfunctor f; |
4258 | \& myfunctor f; |
3624 | \& |
4259 | \& |
3625 | \& ev::io w; |
4260 | \& ev::io w; |
3626 | \& w.set (&f); |
4261 | \& w.set (&f); |
3627 | .Ve |
4262 | .Ve |
… | |
… | |
3645 | .IX Item "w->set (loop)" |
4280 | .IX Item "w->set (loop)" |
3646 | Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only |
4281 | Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only |
3647 | do this when the watcher is inactive (and not pending either). |
4282 | do this when the watcher is inactive (and not pending either). |
3648 | .IP "w\->set ([arguments])" 4 |
4283 | .IP "w\->set ([arguments])" 4 |
3649 | .IX Item "w->set ([arguments])" |
4284 | .IX Item "w->set ([arguments])" |
3650 | Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same arguments. Either this |
4285 | Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR (except for \f(CW\*(C`ev::embed\*(C'\fR watchers>), |
3651 | method or a suitable start method must be called at least once. Unlike the |
4286 | with the same arguments. Either this method or a suitable start method |
3652 | C counterpart, an active watcher gets automatically stopped and restarted |
4287 | must be called at least once. Unlike the C counterpart, an active watcher |
3653 | when reconfiguring it with this method. |
4288 | gets automatically stopped and restarted when reconfiguring it with this |
|
|
4289 | method. |
|
|
4290 | .Sp |
|
|
4291 | For \f(CW\*(C`ev::embed\*(C'\fR watchers this method is called \f(CW\*(C`set_embed\*(C'\fR, to avoid |
|
|
4292 | clashing with the \f(CW\*(C`set (loop)\*(C'\fR method. |
3654 | .IP "w\->start ()" 4 |
4293 | .IP "w\->start ()" 4 |
3655 | .IX Item "w->start ()" |
4294 | .IX Item "w->start ()" |
3656 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the |
4295 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the |
3657 | constructor already stores the event loop. |
4296 | constructor already stores the event loop. |
3658 | .IP "w\->start ([arguments])" 4 |
4297 | .IP "w\->start ([arguments])" 4 |
… | |
… | |
3685 | .PP |
4324 | .PP |
3686 | .Vb 5 |
4325 | .Vb 5 |
3687 | \& class myclass |
4326 | \& class myclass |
3688 | \& { |
4327 | \& { |
3689 | \& ev::io io ; void io_cb (ev::io &w, int revents); |
4328 | \& ev::io io ; void io_cb (ev::io &w, int revents); |
3690 | \& ev::io2 io2 ; void io2_cb (ev::io &w, int revents); |
4329 | \& ev::io io2 ; void io2_cb (ev::io &w, int revents); |
3691 | \& ev::idle idle; void idle_cb (ev::idle &w, int revents); |
4330 | \& ev::idle idle; void idle_cb (ev::idle &w, int revents); |
3692 | \& |
4331 | \& |
3693 | \& myclass (int fd) |
4332 | \& myclass (int fd) |
3694 | \& { |
4333 | \& { |
3695 | \& io .set <myclass, &myclass::io_cb > (this); |
4334 | \& io .set <myclass, &myclass::io_cb > (this); |
… | |
… | |
3716 | there are additional modules that implement libev-compatible interfaces |
4355 | there are additional modules that implement libev-compatible interfaces |
3717 | 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), |
4356 | 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), |
3718 | \&\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 |
4357 | \&\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 |
3719 | and \f(CW\*(C`EV::Glib\*(C'\fR). |
4358 | and \f(CW\*(C`EV::Glib\*(C'\fR). |
3720 | .Sp |
4359 | .Sp |
3721 | It can be found and installed via \s-1CPAN\s0, its homepage is at |
4360 | It can be found and installed via \s-1CPAN,\s0 its homepage is at |
3722 | <http://software.schmorp.de/pkg/EV>. |
4361 | <http://software.schmorp.de/pkg/EV>. |
3723 | .IP "Python" 4 |
4362 | .IP "Python" 4 |
3724 | .IX Item "Python" |
4363 | .IX Item "Python" |
3725 | Python bindings can be found at <http://code.google.com/p/pyev/>. It |
4364 | Python bindings can be found at <http://code.google.com/p/pyev/>. It |
3726 | seems to be quite complete and well-documented. |
4365 | seems to be quite complete and well-documented. |
… | |
… | |
3738 | A haskell binding to libev is available at |
4377 | A haskell binding to libev is available at |
3739 | <http://hackage.haskell.org/cgi\-bin/hackage\-scripts/package/hlibev>. |
4378 | <http://hackage.haskell.org/cgi\-bin/hackage\-scripts/package/hlibev>. |
3740 | .IP "D" 4 |
4379 | .IP "D" 4 |
3741 | .IX Item "D" |
4380 | .IX Item "D" |
3742 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
4381 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
3743 | be found at <http://proj.llucax.com.ar/wiki/evd>. |
4382 | be found at <http://www.llucax.com.ar/proj/ev.d/index.html>. |
3744 | .IP "Ocaml" 4 |
4383 | .IP "Ocaml" 4 |
3745 | .IX Item "Ocaml" |
4384 | .IX Item "Ocaml" |
3746 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
4385 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3747 | <http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/>. |
4386 | <http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/>. |
3748 | .IP "Lua" 4 |
4387 | .IP "Lua" 4 |
3749 | .IX Item "Lua" |
4388 | .IX Item "Lua" |
3750 | Brian Maher has written a partial interface to libev for lua (at the |
4389 | Brian Maher has written a partial interface to libev for lua (at the |
3751 | time of this writing, only \f(CW\*(C`ev_io\*(C'\fR and \f(CW\*(C`ev_timer\*(C'\fR), to be found at |
4390 | time of this writing, only \f(CW\*(C`ev_io\*(C'\fR and \f(CW\*(C`ev_timer\*(C'\fR), to be found at |
3752 | <http://github.com/brimworks/lua\-ev>. |
4391 | <http://github.com/brimworks/lua\-ev>. |
|
|
4392 | .IP "Javascript" 4 |
|
|
4393 | .IX Item "Javascript" |
|
|
4394 | Node.js (<http://nodejs.org>) uses libev as the underlying event library. |
|
|
4395 | .IP "Others" 4 |
|
|
4396 | .IX Item "Others" |
|
|
4397 | There are others, and I stopped counting. |
3753 | .SH "MACRO MAGIC" |
4398 | .SH "MACRO MAGIC" |
3754 | .IX Header "MACRO MAGIC" |
4399 | .IX Header "MACRO MAGIC" |
3755 | Libev can be compiled with a variety of options, the most fundamental |
4400 | Libev can be compiled with a variety of options, the most fundamental |
3756 | of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) |
4401 | of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) |
3757 | functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
4402 | functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
… | |
… | |
3792 | suitable for use with \f(CW\*(C`EV_A\*(C'\fR. |
4437 | suitable for use with \f(CW\*(C`EV_A\*(C'\fR. |
3793 | .ie n .IP """EV_DEFAULT"", ""EV_DEFAULT_""" 4 |
4438 | .ie n .IP """EV_DEFAULT"", ""EV_DEFAULT_""" 4 |
3794 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
4439 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
3795 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
4440 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
3796 | Similar to the other two macros, this gives you the value of the default |
4441 | Similar to the other two macros, this gives you the value of the default |
3797 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). |
4442 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). The default loop |
|
|
4443 | will be initialised if it isn't already initialised. |
|
|
4444 | .Sp |
|
|
4445 | For non-multiplicity builds, these macros do nothing, so you always have |
|
|
4446 | to initialise the loop somewhere. |
3798 | .ie n .IP """EV_DEFAULT_UC"", ""EV_DEFAULT_UC_""" 4 |
4447 | .ie n .IP """EV_DEFAULT_UC"", ""EV_DEFAULT_UC_""" 4 |
3799 | .el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4 |
4448 | .el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4 |
3800 | .IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_" |
4449 | .IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_" |
3801 | Usage identical to \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR, but requires that the |
4450 | Usage identical to \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR, but requires that the |
3802 | default loop has been initialised (\f(CW\*(C`UC\*(C'\fR == unchecked). Their behaviour |
4451 | default loop has been initialised (\f(CW\*(C`UC\*(C'\fR == unchecked). Their behaviour |
… | |
… | |
3836 | .SS "\s-1FILESETS\s0" |
4485 | .SS "\s-1FILESETS\s0" |
3837 | .IX Subsection "FILESETS" |
4486 | .IX Subsection "FILESETS" |
3838 | Depending on what features you need you need to include one or more sets of files |
4487 | Depending on what features you need you need to include one or more sets of files |
3839 | in your application. |
4488 | in your application. |
3840 | .PP |
4489 | .PP |
3841 | \fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR |
4490 | \fI\s-1CORE EVENT LOOP\s0\fR |
3842 | .IX Subsection "CORE EVENT LOOP" |
4491 | .IX Subsection "CORE EVENT LOOP" |
3843 | .PP |
4492 | .PP |
3844 | To include only the libev core (all the \f(CW\*(C`ev_*\*(C'\fR functions), with manual |
4493 | To include only the libev core (all the \f(CW\*(C`ev_*\*(C'\fR functions), with manual |
3845 | configuration (no autoconf): |
4494 | configuration (no autoconf): |
3846 | .PP |
4495 | .PP |
… | |
… | |
3849 | \& #include "ev.c" |
4498 | \& #include "ev.c" |
3850 | .Ve |
4499 | .Ve |
3851 | .PP |
4500 | .PP |
3852 | This will automatically include \fIev.h\fR, too, and should be done in a |
4501 | This will automatically include \fIev.h\fR, too, and should be done in a |
3853 | single C source file only to provide the function implementations. To use |
4502 | single C source file only to provide the function implementations. To use |
3854 | it, do the same for \fIev.h\fR in all files wishing to use this \s-1API\s0 (best |
4503 | it, do the same for \fIev.h\fR in all files wishing to use this \s-1API \s0(best |
3855 | done by writing a wrapper around \fIev.h\fR that you can include instead and |
4504 | done by writing a wrapper around \fIev.h\fR that you can include instead and |
3856 | where you can put other configuration options): |
4505 | where you can put other configuration options): |
3857 | .PP |
4506 | .PP |
3858 | .Vb 2 |
4507 | .Vb 2 |
3859 | \& #define EV_STANDALONE 1 |
4508 | \& #define EV_STANDALONE 1 |
… | |
… | |
3873 | \& ev_vars.h |
4522 | \& ev_vars.h |
3874 | \& ev_wrap.h |
4523 | \& ev_wrap.h |
3875 | \& |
4524 | \& |
3876 | \& ev_win32.c required on win32 platforms only |
4525 | \& ev_win32.c required on win32 platforms only |
3877 | \& |
4526 | \& |
3878 | \& ev_select.c only when select backend is enabled (which is enabled by default) |
4527 | \& ev_select.c only when select backend is enabled |
3879 | \& ev_poll.c only when poll backend is enabled (disabled by default) |
4528 | \& ev_poll.c only when poll backend is enabled |
3880 | \& ev_epoll.c only when the epoll backend is enabled (disabled by default) |
4529 | \& ev_epoll.c only when the epoll backend is enabled |
3881 | \& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
4530 | \& ev_kqueue.c only when the kqueue backend is enabled |
3882 | \& ev_port.c only when the solaris port backend is enabled (disabled by default) |
4531 | \& ev_port.c only when the solaris port backend is enabled |
3883 | .Ve |
4532 | .Ve |
3884 | .PP |
4533 | .PP |
3885 | \&\fIev.c\fR includes the backend files directly when enabled, so you only need |
4534 | \&\fIev.c\fR includes the backend files directly when enabled, so you only need |
3886 | to compile this single file. |
4535 | to compile this single file. |
3887 | .PP |
4536 | .PP |
3888 | \fI\s-1LIBEVENT\s0 \s-1COMPATIBILITY\s0 \s-1API\s0\fR |
4537 | \fI\s-1LIBEVENT COMPATIBILITY API\s0\fR |
3889 | .IX Subsection "LIBEVENT COMPATIBILITY API" |
4538 | .IX Subsection "LIBEVENT COMPATIBILITY API" |
3890 | .PP |
4539 | .PP |
3891 | To include the libevent compatibility \s-1API\s0, also include: |
4540 | To include the libevent compatibility \s-1API,\s0 also include: |
3892 | .PP |
4541 | .PP |
3893 | .Vb 1 |
4542 | .Vb 1 |
3894 | \& #include "event.c" |
4543 | \& #include "event.c" |
3895 | .Ve |
4544 | .Ve |
3896 | .PP |
4545 | .PP |
… | |
… | |
3898 | .PP |
4547 | .PP |
3899 | .Vb 1 |
4548 | .Vb 1 |
3900 | \& #include "event.h" |
4549 | \& #include "event.h" |
3901 | .Ve |
4550 | .Ve |
3902 | .PP |
4551 | .PP |
3903 | in the files that want to use the libevent \s-1API\s0. This also includes \fIev.h\fR. |
4552 | in the files that want to use the libevent \s-1API.\s0 This also includes \fIev.h\fR. |
3904 | .PP |
4553 | .PP |
3905 | You need the following additional files for this: |
4554 | You need the following additional files for this: |
3906 | .PP |
4555 | .PP |
3907 | .Vb 2 |
4556 | .Vb 2 |
3908 | \& event.h |
4557 | \& event.h |
3909 | \& event.c |
4558 | \& event.c |
3910 | .Ve |
4559 | .Ve |
3911 | .PP |
4560 | .PP |
3912 | \fI\s-1AUTOCONF\s0 \s-1SUPPORT\s0\fR |
4561 | \fI\s-1AUTOCONF SUPPORT\s0\fR |
3913 | .IX Subsection "AUTOCONF SUPPORT" |
4562 | .IX Subsection "AUTOCONF SUPPORT" |
3914 | .PP |
4563 | .PP |
3915 | Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your configuration in |
4564 | Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your configuration in |
3916 | whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your |
4565 | whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your |
3917 | \&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then |
4566 | \&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then |
… | |
… | |
3920 | For this of course you need the m4 file: |
4569 | For this of course you need the m4 file: |
3921 | .PP |
4570 | .PP |
3922 | .Vb 1 |
4571 | .Vb 1 |
3923 | \& libev.m4 |
4572 | \& libev.m4 |
3924 | .Ve |
4573 | .Ve |
3925 | .SS "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" |
4574 | .SS "\s-1PREPROCESSOR SYMBOLS/MACROS\s0" |
3926 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
4575 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
3927 | Libev can be configured via a variety of preprocessor symbols you have to |
4576 | Libev can be configured via a variety of preprocessor symbols you have to |
3928 | define before including (or compiling) any of its files. The default in |
4577 | define before including (or compiling) any of its files. The default in |
3929 | the absence of autoconf is documented for every option. |
4578 | the absence of autoconf is documented for every option. |
3930 | .PP |
4579 | .PP |
3931 | Symbols marked with \*(L"(h)\*(R" do not change the \s-1ABI\s0, and can have different |
4580 | Symbols marked with \*(L"(h)\*(R" do not change the \s-1ABI,\s0 and can have different |
3932 | values when compiling libev vs. including \fIev.h\fR, so it is permissible |
4581 | values when compiling libev vs. including \fIev.h\fR, so it is permissible |
3933 | to redefine them before including \fIev.h\fR without breaking compatibility |
4582 | to redefine them before including \fIev.h\fR without breaking compatibility |
3934 | to a compiled library. All other symbols change the \s-1ABI\s0, which means all |
4583 | to a compiled library. All other symbols change the \s-1ABI,\s0 which means all |
3935 | users of libev and the libev code itself must be compiled with compatible |
4584 | users of libev and the libev code itself must be compiled with compatible |
3936 | settings. |
4585 | settings. |
3937 | .IP "\s-1EV_COMPAT3\s0 (h)" 4 |
4586 | .IP "\s-1EV_COMPAT3 \s0(h)" 4 |
3938 | .IX Item "EV_COMPAT3 (h)" |
4587 | .IX Item "EV_COMPAT3 (h)" |
3939 | Backwards compatibility is a major concern for libev. This is why this |
4588 | Backwards compatibility is a major concern for libev. This is why this |
3940 | release of libev comes with wrappers for the functions and symbols that |
4589 | release of libev comes with wrappers for the functions and symbols that |
3941 | have been renamed between libev version 3 and 4. |
4590 | have been renamed between libev version 3 and 4. |
3942 | .Sp |
4591 | .Sp |
… | |
… | |
3947 | typedef in that case. |
4596 | typedef in that case. |
3948 | .Sp |
4597 | .Sp |
3949 | In some future version, the default for \f(CW\*(C`EV_COMPAT3\*(C'\fR will become \f(CW0\fR, |
4598 | In some future version, the default for \f(CW\*(C`EV_COMPAT3\*(C'\fR will become \f(CW0\fR, |
3950 | and in some even more future version the compatibility code will be |
4599 | and in some even more future version the compatibility code will be |
3951 | removed completely. |
4600 | removed completely. |
3952 | .IP "\s-1EV_STANDALONE\s0 (h)" 4 |
4601 | .IP "\s-1EV_STANDALONE \s0(h)" 4 |
3953 | .IX Item "EV_STANDALONE (h)" |
4602 | .IX Item "EV_STANDALONE (h)" |
3954 | Must always be \f(CW1\fR if you do not use autoconf configuration, which |
4603 | Must always be \f(CW1\fR if you do not use autoconf configuration, which |
3955 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
4604 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
3956 | implementations for some libevent functions (such as logging, which is not |
4605 | implementations for some libevent functions (such as logging, which is not |
3957 | supported). It will also not define any of the structs usually found in |
4606 | supported). It will also not define any of the structs usually found in |
3958 | \&\fIevent.h\fR that are not directly supported by the libev core alone. |
4607 | \&\fIevent.h\fR that are not directly supported by the libev core alone. |
3959 | .Sp |
4608 | .Sp |
3960 | In standalone mode, libev will still try to automatically deduce the |
4609 | In standalone mode, libev will still try to automatically deduce the |
3961 | configuration, but has to be more conservative. |
4610 | configuration, but has to be more conservative. |
|
|
4611 | .IP "\s-1EV_USE_FLOOR\s0" 4 |
|
|
4612 | .IX Item "EV_USE_FLOOR" |
|
|
4613 | If defined to be \f(CW1\fR, libev will use the \f(CW\*(C`floor ()\*(C'\fR function for its |
|
|
4614 | periodic reschedule calculations, otherwise libev will fall back on a |
|
|
4615 | portable (slower) implementation. If you enable this, you usually have to |
|
|
4616 | link against libm or something equivalent. Enabling this when the \f(CW\*(C`floor\*(C'\fR |
|
|
4617 | function is not available will fail, so the safe default is to not enable |
|
|
4618 | this. |
3962 | .IP "\s-1EV_USE_MONOTONIC\s0" 4 |
4619 | .IP "\s-1EV_USE_MONOTONIC\s0" 4 |
3963 | .IX Item "EV_USE_MONOTONIC" |
4620 | .IX Item "EV_USE_MONOTONIC" |
3964 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
4621 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
3965 | monotonic clock option at both compile time and runtime. Otherwise no |
4622 | monotonic clock option at both compile time and runtime. Otherwise no |
3966 | use of the monotonic clock option will be attempted. If you enable this, |
4623 | use of the monotonic clock option will be attempted. If you enable this, |
… | |
… | |
4040 | .IX Item "EV_WIN32_CLOSE_FD(fd)" |
4697 | .IX Item "EV_WIN32_CLOSE_FD(fd)" |
4041 | If programs implement their own fd to handle mapping on win32, then this |
4698 | If programs implement their own fd to handle mapping on win32, then this |
4042 | macro can be used to override the \f(CW\*(C`close\*(C'\fR function, useful to unregister |
4699 | macro can be used to override the \f(CW\*(C`close\*(C'\fR function, useful to unregister |
4043 | file descriptors again. Note that the replacement function has to close |
4700 | file descriptors again. Note that the replacement function has to close |
4044 | the underlying \s-1OS\s0 handle. |
4701 | the underlying \s-1OS\s0 handle. |
|
|
4702 | .IP "\s-1EV_USE_WSASOCKET\s0" 4 |
|
|
4703 | .IX Item "EV_USE_WSASOCKET" |
|
|
4704 | If defined to be \f(CW1\fR, libev will use \f(CW\*(C`WSASocket\*(C'\fR to create its internal |
|
|
4705 | communication socket, which works better in some environments. Otherwise, |
|
|
4706 | the normal \f(CW\*(C`socket\*(C'\fR function will be used, which works better in other |
|
|
4707 | environments. |
4045 | .IP "\s-1EV_USE_POLL\s0" 4 |
4708 | .IP "\s-1EV_USE_POLL\s0" 4 |
4046 | .IX Item "EV_USE_POLL" |
4709 | .IX Item "EV_USE_POLL" |
4047 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
4710 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
4048 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
4711 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
4049 | takes precedence over select. |
4712 | takes precedence over select. |
… | |
… | |
4078 | .IX Item "EV_USE_INOTIFY" |
4741 | .IX Item "EV_USE_INOTIFY" |
4079 | If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify |
4742 | If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify |
4080 | interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will |
4743 | interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will |
4081 | be detected at runtime. If undefined, it will be enabled if the headers |
4744 | be detected at runtime. If undefined, it will be enabled if the headers |
4082 | indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
4745 | indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
|
|
4746 | .IP "\s-1EV_NO_SMP\s0" 4 |
|
|
4747 | .IX Item "EV_NO_SMP" |
|
|
4748 | If defined to be \f(CW1\fR, libev will assume that memory is always coherent |
|
|
4749 | between threads, that is, threads can be used, but threads never run on |
|
|
4750 | different cpus (or different cpu cores). This reduces dependencies |
|
|
4751 | and makes libev faster. |
|
|
4752 | .IP "\s-1EV_NO_THREADS\s0" 4 |
|
|
4753 | .IX Item "EV_NO_THREADS" |
|
|
4754 | If defined to be \f(CW1\fR, libev will assume that it will never be called from |
|
|
4755 | different threads (that includes signal handlers), which is a stronger |
|
|
4756 | assumption than \f(CW\*(C`EV_NO_SMP\*(C'\fR, above. This reduces dependencies and makes |
|
|
4757 | libev faster. |
4083 | .IP "\s-1EV_ATOMIC_T\s0" 4 |
4758 | .IP "\s-1EV_ATOMIC_T\s0" 4 |
4084 | .IX Item "EV_ATOMIC_T" |
4759 | .IX Item "EV_ATOMIC_T" |
4085 | Libev requires an integer type (suitable for storing \f(CW0\fR or \f(CW1\fR) whose |
4760 | Libev requires an integer type (suitable for storing \f(CW0\fR or \f(CW1\fR) whose |
4086 | access is atomic with respect to other threads or signal contexts. No such |
4761 | access is atomic with respect to other threads or signal contexts. No |
4087 | type is easily found in the C language, so you can provide your own type |
4762 | such type is easily found in the C language, so you can provide your own |
4088 | that you know is safe for your purposes. It is used both for signal handler \*(L"locking\*(R" |
4763 | type that you know is safe for your purposes. It is used both for signal |
4089 | as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR watchers. |
4764 | handler \*(L"locking\*(R" as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR |
|
|
4765 | watchers. |
4090 | .Sp |
4766 | .Sp |
4091 | In the absence of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR |
4767 | In the absence of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR |
4092 | (from \fIsignal.h\fR), which is usually good enough on most platforms. |
4768 | (from \fIsignal.h\fR), which is usually good enough on most platforms. |
4093 | .IP "\s-1EV_H\s0 (h)" 4 |
4769 | .IP "\s-1EV_H \s0(h)" 4 |
4094 | .IX Item "EV_H (h)" |
4770 | .IX Item "EV_H (h)" |
4095 | The name of the \fIev.h\fR header file used to include it. The default if |
4771 | The name of the \fIev.h\fR header file used to include it. The default if |
4096 | undefined is \f(CW"ev.h"\fR in \fIevent.h\fR, \fIev.c\fR and \fIev++.h\fR. This can be |
4772 | undefined is \f(CW"ev.h"\fR in \fIevent.h\fR, \fIev.c\fR and \fIev++.h\fR. This can be |
4097 | used to virtually rename the \fIev.h\fR header file in case of conflicts. |
4773 | used to virtually rename the \fIev.h\fR header file in case of conflicts. |
4098 | .IP "\s-1EV_CONFIG_H\s0 (h)" 4 |
4774 | .IP "\s-1EV_CONFIG_H \s0(h)" 4 |
4099 | .IX Item "EV_CONFIG_H (h)" |
4775 | .IX Item "EV_CONFIG_H (h)" |
4100 | If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override |
4776 | If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override |
4101 | \&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to |
4777 | \&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to |
4102 | \&\f(CW\*(C`EV_H\*(C'\fR, above. |
4778 | \&\f(CW\*(C`EV_H\*(C'\fR, above. |
4103 | .IP "\s-1EV_EVENT_H\s0 (h)" 4 |
4779 | .IP "\s-1EV_EVENT_H \s0(h)" 4 |
4104 | .IX Item "EV_EVENT_H (h)" |
4780 | .IX Item "EV_EVENT_H (h)" |
4105 | Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea |
4781 | Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea |
4106 | of how the \fIevent.h\fR header can be found, the default is \f(CW"event.h"\fR. |
4782 | of how the \fIevent.h\fR header can be found, the default is \f(CW"event.h"\fR. |
4107 | .IP "\s-1EV_PROTOTYPES\s0 (h)" 4 |
4783 | .IP "\s-1EV_PROTOTYPES \s0(h)" 4 |
4108 | .IX Item "EV_PROTOTYPES (h)" |
4784 | .IX Item "EV_PROTOTYPES (h)" |
4109 | If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function |
4785 | If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function |
4110 | prototypes, but still define all the structs and other symbols. This is |
4786 | prototypes, but still define all the structs and other symbols. This is |
4111 | occasionally useful if you want to provide your own wrapper functions |
4787 | occasionally useful if you want to provide your own wrapper functions |
4112 | around libev functions. |
4788 | around libev functions. |
… | |
… | |
4115 | If undefined or defined to \f(CW1\fR, then all event-loop-specific functions |
4791 | If undefined or defined to \f(CW1\fR, then all event-loop-specific functions |
4116 | will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create |
4792 | will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create |
4117 | additional independent event loops. Otherwise there will be no support |
4793 | additional independent event loops. Otherwise there will be no support |
4118 | for multiple event loops and there is no first event loop pointer |
4794 | for multiple event loops and there is no first event loop pointer |
4119 | argument. Instead, all functions act on the single default loop. |
4795 | argument. Instead, all functions act on the single default loop. |
|
|
4796 | .Sp |
|
|
4797 | Note that \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR will no longer provide a |
|
|
4798 | default loop when multiplicity is switched off \- you always have to |
|
|
4799 | initialise the loop manually in this case. |
4120 | .IP "\s-1EV_MINPRI\s0" 4 |
4800 | .IP "\s-1EV_MINPRI\s0" 4 |
4121 | .IX Item "EV_MINPRI" |
4801 | .IX Item "EV_MINPRI" |
4122 | .PD 0 |
4802 | .PD 0 |
4123 | .IP "\s-1EV_MAXPRI\s0" 4 |
4803 | .IP "\s-1EV_MAXPRI\s0" 4 |
4124 | .IX Item "EV_MAXPRI" |
4804 | .IX Item "EV_MAXPRI" |
… | |
… | |
4132 | all the priorities, so having many of them (hundreds) uses a lot of space |
4812 | all the priorities, so having many of them (hundreds) uses a lot of space |
4133 | and time, so using the defaults of five priorities (\-2 .. +2) is usually |
4813 | and time, so using the defaults of five priorities (\-2 .. +2) is usually |
4134 | fine. |
4814 | fine. |
4135 | .Sp |
4815 | .Sp |
4136 | If your embedding application does not need any priorities, defining these |
4816 | If your embedding application does not need any priorities, defining these |
4137 | both to \f(CW0\fR will save some memory and \s-1CPU\s0. |
4817 | both to \f(CW0\fR will save some memory and \s-1CPU.\s0 |
4138 | .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 |
4818 | .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 |
4139 | .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." |
4819 | .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." |
4140 | If undefined or defined to be \f(CW1\fR (and the platform supports it), then |
4820 | If undefined or defined to be \f(CW1\fR (and the platform supports it), then |
4141 | the respective watcher type is supported. If defined to be \f(CW0\fR, then it |
4821 | the respective watcher type is supported. If defined to be \f(CW0\fR, then it |
4142 | is not. Disabling watcher types mainly saves code size. |
4822 | is not. Disabling watcher types mainly saves code size. |
4143 | .IP "\s-1EV_FEATURES\s0" 4 |
4823 | .IP "\s-1EV_FEATURES\s0" 4 |
… | |
… | |
4160 | \& #define EV_CHILD_ENABLE 1 |
4840 | \& #define EV_CHILD_ENABLE 1 |
4161 | \& #define EV_ASYNC_ENABLE 1 |
4841 | \& #define EV_ASYNC_ENABLE 1 |
4162 | .Ve |
4842 | .Ve |
4163 | .Sp |
4843 | .Sp |
4164 | The actual value is a bitset, it can be a combination of the following |
4844 | The actual value is a bitset, it can be a combination of the following |
4165 | values: |
4845 | values (by default, all of these are enabled): |
4166 | .RS 4 |
4846 | .RS 4 |
4167 | .ie n .IP "1 \- faster/larger code" 4 |
4847 | .ie n .IP "1 \- faster/larger code" 4 |
4168 | .el .IP "\f(CW1\fR \- faster/larger code" 4 |
4848 | .el .IP "\f(CW1\fR \- faster/larger code" 4 |
4169 | .IX Item "1 - faster/larger code" |
4849 | .IX Item "1 - faster/larger code" |
4170 | Use larger code to speed up some operations. |
4850 | Use larger code to speed up some operations. |
… | |
… | |
4173 | code size by roughly 30% on amd64). |
4853 | code size by roughly 30% on amd64). |
4174 | .Sp |
4854 | .Sp |
4175 | When optimising for size, use of compiler flags such as \f(CW\*(C`\-Os\*(C'\fR with |
4855 | When optimising for size, use of compiler flags such as \f(CW\*(C`\-Os\*(C'\fR with |
4176 | gcc is recommended, as well as \f(CW\*(C`\-DNDEBUG\*(C'\fR, as libev contains a number of |
4856 | gcc is recommended, as well as \f(CW\*(C`\-DNDEBUG\*(C'\fR, as libev contains a number of |
4177 | assertions. |
4857 | assertions. |
|
|
4858 | .Sp |
|
|
4859 | The default is off when \f(CW\*(C`_\|_OPTIMIZE_SIZE_\|_\*(C'\fR is defined by your compiler |
|
|
4860 | (e.g. gcc with \f(CW\*(C`\-Os\*(C'\fR). |
4178 | .ie n .IP "2 \- faster/larger data structures" 4 |
4861 | .ie n .IP "2 \- faster/larger data structures" 4 |
4179 | .el .IP "\f(CW2\fR \- faster/larger data structures" 4 |
4862 | .el .IP "\f(CW2\fR \- faster/larger data structures" 4 |
4180 | .IX Item "2 - faster/larger data structures" |
4863 | .IX Item "2 - faster/larger data structures" |
4181 | Replaces the small 2\-heap for timer management by a faster 4\-heap, larger |
4864 | Replaces the small 2\-heap for timer management by a faster 4\-heap, larger |
4182 | hash table sizes and so on. This will usually further increase code size |
4865 | hash table sizes and so on. This will usually further increase code size |
4183 | and can additionally have an effect on the size of data structures at |
4866 | and can additionally have an effect on the size of data structures at |
4184 | runtime. |
4867 | runtime. |
|
|
4868 | .Sp |
|
|
4869 | The default is off when \f(CW\*(C`_\|_OPTIMIZE_SIZE_\|_\*(C'\fR is defined by your compiler |
|
|
4870 | (e.g. gcc with \f(CW\*(C`\-Os\*(C'\fR). |
4185 | .ie n .IP "4 \- full \s-1API\s0 configuration" 4 |
4871 | .ie n .IP "4 \- full \s-1API\s0 configuration" 4 |
4186 | .el .IP "\f(CW4\fR \- full \s-1API\s0 configuration" 4 |
4872 | .el .IP "\f(CW4\fR \- full \s-1API\s0 configuration" 4 |
4187 | .IX Item "4 - full API configuration" |
4873 | .IX Item "4 - full API configuration" |
4188 | This enables priorities (sets \f(CW\*(C`EV_MAXPRI\*(C'\fR=2 and \f(CW\*(C`EV_MINPRI\*(C'\fR=\-2), and |
4874 | This enables priorities (sets \f(CW\*(C`EV_MAXPRI\*(C'\fR=2 and \f(CW\*(C`EV_MINPRI\*(C'\fR=\-2), and |
4189 | enables multiplicity (\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR=1). |
4875 | enables multiplicity (\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR=1). |
… | |
… | |
4221 | With an intelligent-enough linker (gcc+binutils are intelligent enough |
4907 | With an intelligent-enough linker (gcc+binutils are intelligent enough |
4222 | when you use \f(CW\*(C`\-Wl,\-\-gc\-sections \-ffunction\-sections\*(C'\fR) functions unused by |
4908 | when you use \f(CW\*(C`\-Wl,\-\-gc\-sections \-ffunction\-sections\*(C'\fR) functions unused by |
4223 | your program might be left out as well \- a binary starting a timer and an |
4909 | your program might be left out as well \- a binary starting a timer and an |
4224 | I/O watcher then might come out at only 5Kb. |
4910 | I/O watcher then might come out at only 5Kb. |
4225 | .RE |
4911 | .RE |
|
|
4912 | .IP "\s-1EV_API_STATIC\s0" 4 |
|
|
4913 | .IX Item "EV_API_STATIC" |
|
|
4914 | If this symbol is defined (by default it is not), then all identifiers |
|
|
4915 | will have static linkage. This means that libev will not export any |
|
|
4916 | identifiers, and you cannot link against libev anymore. This can be useful |
|
|
4917 | when you embed libev, only want to use libev functions in a single file, |
|
|
4918 | and do not want its identifiers to be visible. |
|
|
4919 | .Sp |
|
|
4920 | To use this, define \f(CW\*(C`EV_API_STATIC\*(C'\fR and include \fIev.c\fR in the file that |
|
|
4921 | wants to use libev. |
|
|
4922 | .Sp |
|
|
4923 | This option only works when libev is compiled with a C compiler, as \*(C+ |
|
|
4924 | doesn't support the required declaration syntax. |
4226 | .IP "\s-1EV_AVOID_STDIO\s0" 4 |
4925 | .IP "\s-1EV_AVOID_STDIO\s0" 4 |
4227 | .IX Item "EV_AVOID_STDIO" |
4926 | .IX Item "EV_AVOID_STDIO" |
4228 | If this is set to \f(CW1\fR at compiletime, then libev will avoid using stdio |
4927 | If this is set to \f(CW1\fR at compiletime, then libev will avoid using stdio |
4229 | functions (printf, scanf, perror etc.). This will increase the code size |
4928 | functions (printf, scanf, perror etc.). This will increase the code size |
4230 | somewhat, but if your program doesn't otherwise depend on stdio and your |
4929 | somewhat, but if your program doesn't otherwise depend on stdio and your |
… | |
… | |
4298 | .Vb 3 |
4997 | .Vb 3 |
4299 | \& #define EV_COMMON \e |
4998 | \& #define EV_COMMON \e |
4300 | \& SV *self; /* contains this struct */ \e |
4999 | \& SV *self; /* contains this struct */ \e |
4301 | \& SV *cb_sv, *fh /* note no trailing ";" */ |
5000 | \& SV *cb_sv, *fh /* note no trailing ";" */ |
4302 | .Ve |
5001 | .Ve |
4303 | .IP "\s-1EV_CB_DECLARE\s0 (type)" 4 |
5002 | .IP "\s-1EV_CB_DECLARE \s0(type)" 4 |
4304 | .IX Item "EV_CB_DECLARE (type)" |
5003 | .IX Item "EV_CB_DECLARE (type)" |
4305 | .PD 0 |
5004 | .PD 0 |
4306 | .IP "\s-1EV_CB_INVOKE\s0 (watcher, revents)" 4 |
5005 | .IP "\s-1EV_CB_INVOKE \s0(watcher, revents)" 4 |
4307 | .IX Item "EV_CB_INVOKE (watcher, revents)" |
5006 | .IX Item "EV_CB_INVOKE (watcher, revents)" |
4308 | .IP "ev_set_cb (ev, cb)" 4 |
5007 | .IP "ev_set_cb (ev, cb)" 4 |
4309 | .IX Item "ev_set_cb (ev, cb)" |
5008 | .IX Item "ev_set_cb (ev, cb)" |
4310 | .PD |
5009 | .PD |
4311 | Can be used to change the callback member declaration in each watcher, |
5010 | Can be used to change the callback member declaration in each watcher, |
4312 | and the way callbacks are invoked and set. Must expand to a struct member |
5011 | and the way callbacks are invoked and set. Must expand to a struct member |
4313 | definition and a statement, respectively. See the \fIev.h\fR header file for |
5012 | definition and a statement, respectively. See the \fIev.h\fR header file for |
4314 | their default definitions. One possible use for overriding these is to |
5013 | their default definitions. One possible use for overriding these is to |
4315 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
5014 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
4316 | method calls instead of plain function calls in \*(C+. |
5015 | method calls instead of plain function calls in \*(C+. |
4317 | .SS "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0" |
5016 | .SS "\s-1EXPORTED API SYMBOLS\s0" |
4318 | .IX Subsection "EXPORTED API SYMBOLS" |
5017 | .IX Subsection "EXPORTED API SYMBOLS" |
4319 | If you need to re-export the \s-1API\s0 (e.g. via a \s-1DLL\s0) and you need a list of |
5018 | If you need to re-export the \s-1API \s0(e.g. via a \s-1DLL\s0) and you need a list of |
4320 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
5019 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
4321 | all public symbols, one per line: |
5020 | all public symbols, one per line: |
4322 | .PP |
5021 | .PP |
4323 | .Vb 2 |
5022 | .Vb 2 |
4324 | \& Symbols.ev for libev proper |
5023 | \& Symbols.ev for libev proper |
… | |
… | |
4374 | .PP |
5073 | .PP |
4375 | .Vb 2 |
5074 | .Vb 2 |
4376 | \& #include "ev_cpp.h" |
5075 | \& #include "ev_cpp.h" |
4377 | \& #include "ev.c" |
5076 | \& #include "ev.c" |
4378 | .Ve |
5077 | .Ve |
4379 | .SH "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES" |
5078 | .SH "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT" |
4380 | .IX Header "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES" |
5079 | .IX Header "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT" |
4381 | .SS "\s-1THREADS\s0 \s-1AND\s0 \s-1COROUTINES\s0" |
5080 | .SS "\s-1THREADS AND COROUTINES\s0" |
4382 | .IX Subsection "THREADS AND COROUTINES" |
5081 | .IX Subsection "THREADS AND COROUTINES" |
4383 | \fI\s-1THREADS\s0\fR |
5082 | \fI\s-1THREADS\s0\fR |
4384 | .IX Subsection "THREADS" |
5083 | .IX Subsection "THREADS" |
4385 | .PP |
5084 | .PP |
4386 | All libev functions are reentrant and thread-safe unless explicitly |
5085 | All libev functions are reentrant and thread-safe unless explicitly |
… | |
… | |
4432 | An example use would be to communicate signals or other events that only |
5131 | An example use would be to communicate signals or other events that only |
4433 | work in the default loop by registering the signal watcher with the |
5132 | work in the default loop by registering the signal watcher with the |
4434 | default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop |
5133 | default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop |
4435 | watcher callback into the event loop interested in the signal. |
5134 | watcher callback into the event loop interested in the signal. |
4436 | .PP |
5135 | .PP |
4437 | \s-1THREAD\s0 \s-1LOCKING\s0 \s-1EXAMPLE\s0 |
5136 | See also \*(L"\s-1THREAD LOCKING EXAMPLE\*(R"\s0. |
4438 | .IX Subsection "THREAD LOCKING EXAMPLE" |
|
|
4439 | .PP |
|
|
4440 | Here is a fictitious example of how to run an event loop in a different |
|
|
4441 | thread than where callbacks are being invoked and watchers are |
|
|
4442 | created/added/removed. |
|
|
4443 | .PP |
|
|
4444 | For a real-world example, see the \f(CW\*(C`EV::Loop::Async\*(C'\fR perl module, |
|
|
4445 | which uses exactly this technique (which is suited for many high-level |
|
|
4446 | languages). |
|
|
4447 | .PP |
|
|
4448 | The example uses a pthread mutex to protect the loop data, a condition |
|
|
4449 | variable to wait for callback invocations, an async watcher to notify the |
|
|
4450 | event loop thread and an unspecified mechanism to wake up the main thread. |
|
|
4451 | .PP |
|
|
4452 | First, you need to associate some data with the event loop: |
|
|
4453 | .PP |
|
|
4454 | .Vb 6 |
|
|
4455 | \& typedef struct { |
|
|
4456 | \& mutex_t lock; /* global loop lock */ |
|
|
4457 | \& ev_async async_w; |
|
|
4458 | \& thread_t tid; |
|
|
4459 | \& cond_t invoke_cv; |
|
|
4460 | \& } userdata; |
|
|
4461 | \& |
|
|
4462 | \& void prepare_loop (EV_P) |
|
|
4463 | \& { |
|
|
4464 | \& // for simplicity, we use a static userdata struct. |
|
|
4465 | \& static userdata u; |
|
|
4466 | \& |
|
|
4467 | \& ev_async_init (&u\->async_w, async_cb); |
|
|
4468 | \& ev_async_start (EV_A_ &u\->async_w); |
|
|
4469 | \& |
|
|
4470 | \& pthread_mutex_init (&u\->lock, 0); |
|
|
4471 | \& pthread_cond_init (&u\->invoke_cv, 0); |
|
|
4472 | \& |
|
|
4473 | \& // now associate this with the loop |
|
|
4474 | \& ev_set_userdata (EV_A_ u); |
|
|
4475 | \& ev_set_invoke_pending_cb (EV_A_ l_invoke); |
|
|
4476 | \& ev_set_loop_release_cb (EV_A_ l_release, l_acquire); |
|
|
4477 | \& |
|
|
4478 | \& // then create the thread running ev_loop |
|
|
4479 | \& pthread_create (&u\->tid, 0, l_run, EV_A); |
|
|
4480 | \& } |
|
|
4481 | .Ve |
|
|
4482 | .PP |
|
|
4483 | The callback for the \f(CW\*(C`ev_async\*(C'\fR watcher does nothing: the watcher is used |
|
|
4484 | solely to wake up the event loop so it takes notice of any new watchers |
|
|
4485 | that might have been added: |
|
|
4486 | .PP |
|
|
4487 | .Vb 5 |
|
|
4488 | \& static void |
|
|
4489 | \& async_cb (EV_P_ ev_async *w, int revents) |
|
|
4490 | \& { |
|
|
4491 | \& // just used for the side effects |
|
|
4492 | \& } |
|
|
4493 | .Ve |
|
|
4494 | .PP |
|
|
4495 | The \f(CW\*(C`l_release\*(C'\fR and \f(CW\*(C`l_acquire\*(C'\fR callbacks simply unlock/lock the mutex |
|
|
4496 | protecting the loop data, respectively. |
|
|
4497 | .PP |
|
|
4498 | .Vb 6 |
|
|
4499 | \& static void |
|
|
4500 | \& l_release (EV_P) |
|
|
4501 | \& { |
|
|
4502 | \& userdata *u = ev_userdata (EV_A); |
|
|
4503 | \& pthread_mutex_unlock (&u\->lock); |
|
|
4504 | \& } |
|
|
4505 | \& |
|
|
4506 | \& static void |
|
|
4507 | \& l_acquire (EV_P) |
|
|
4508 | \& { |
|
|
4509 | \& userdata *u = ev_userdata (EV_A); |
|
|
4510 | \& pthread_mutex_lock (&u\->lock); |
|
|
4511 | \& } |
|
|
4512 | .Ve |
|
|
4513 | .PP |
|
|
4514 | The event loop thread first acquires the mutex, and then jumps straight |
|
|
4515 | into \f(CW\*(C`ev_run\*(C'\fR: |
|
|
4516 | .PP |
|
|
4517 | .Vb 4 |
|
|
4518 | \& void * |
|
|
4519 | \& l_run (void *thr_arg) |
|
|
4520 | \& { |
|
|
4521 | \& struct ev_loop *loop = (struct ev_loop *)thr_arg; |
|
|
4522 | \& |
|
|
4523 | \& l_acquire (EV_A); |
|
|
4524 | \& pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
|
|
4525 | \& ev_run (EV_A_ 0); |
|
|
4526 | \& l_release (EV_A); |
|
|
4527 | \& |
|
|
4528 | \& return 0; |
|
|
4529 | \& } |
|
|
4530 | .Ve |
|
|
4531 | .PP |
|
|
4532 | Instead of invoking all pending watchers, the \f(CW\*(C`l_invoke\*(C'\fR callback will |
|
|
4533 | signal the main thread via some unspecified mechanism (signals? pipe |
|
|
4534 | writes? \f(CW\*(C`Async::Interrupt\*(C'\fR?) and then waits until all pending watchers |
|
|
4535 | have been called (in a while loop because a) spurious wakeups are possible |
|
|
4536 | and b) skipping inter-thread-communication when there are no pending |
|
|
4537 | watchers is very beneficial): |
|
|
4538 | .PP |
|
|
4539 | .Vb 4 |
|
|
4540 | \& static void |
|
|
4541 | \& l_invoke (EV_P) |
|
|
4542 | \& { |
|
|
4543 | \& userdata *u = ev_userdata (EV_A); |
|
|
4544 | \& |
|
|
4545 | \& while (ev_pending_count (EV_A)) |
|
|
4546 | \& { |
|
|
4547 | \& wake_up_other_thread_in_some_magic_or_not_so_magic_way (); |
|
|
4548 | \& pthread_cond_wait (&u\->invoke_cv, &u\->lock); |
|
|
4549 | \& } |
|
|
4550 | \& } |
|
|
4551 | .Ve |
|
|
4552 | .PP |
|
|
4553 | Now, whenever the main thread gets told to invoke pending watchers, it |
|
|
4554 | will grab the lock, call \f(CW\*(C`ev_invoke_pending\*(C'\fR and then signal the loop |
|
|
4555 | thread to continue: |
|
|
4556 | .PP |
|
|
4557 | .Vb 4 |
|
|
4558 | \& static void |
|
|
4559 | \& real_invoke_pending (EV_P) |
|
|
4560 | \& { |
|
|
4561 | \& userdata *u = ev_userdata (EV_A); |
|
|
4562 | \& |
|
|
4563 | \& pthread_mutex_lock (&u\->lock); |
|
|
4564 | \& ev_invoke_pending (EV_A); |
|
|
4565 | \& pthread_cond_signal (&u\->invoke_cv); |
|
|
4566 | \& pthread_mutex_unlock (&u\->lock); |
|
|
4567 | \& } |
|
|
4568 | .Ve |
|
|
4569 | .PP |
|
|
4570 | Whenever you want to start/stop a watcher or do other modifications to an |
|
|
4571 | event loop, you will now have to lock: |
|
|
4572 | .PP |
|
|
4573 | .Vb 2 |
|
|
4574 | \& ev_timer timeout_watcher; |
|
|
4575 | \& userdata *u = ev_userdata (EV_A); |
|
|
4576 | \& |
|
|
4577 | \& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
|
|
4578 | \& |
|
|
4579 | \& pthread_mutex_lock (&u\->lock); |
|
|
4580 | \& ev_timer_start (EV_A_ &timeout_watcher); |
|
|
4581 | \& ev_async_send (EV_A_ &u\->async_w); |
|
|
4582 | \& pthread_mutex_unlock (&u\->lock); |
|
|
4583 | .Ve |
|
|
4584 | .PP |
|
|
4585 | Note that sending the \f(CW\*(C`ev_async\*(C'\fR watcher is required because otherwise |
|
|
4586 | an event loop currently blocking in the kernel will have no knowledge |
|
|
4587 | about the newly added timer. By waking up the loop it will pick up any new |
|
|
4588 | watchers in the next event loop iteration. |
|
|
4589 | .PP |
5137 | .PP |
4590 | \fI\s-1COROUTINES\s0\fR |
5138 | \fI\s-1COROUTINES\s0\fR |
4591 | .IX Subsection "COROUTINES" |
5139 | .IX Subsection "COROUTINES" |
4592 | .PP |
5140 | .PP |
4593 | Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"): |
5141 | Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"): |
… | |
… | |
4598 | that you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. |
5146 | that you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. |
4599 | .PP |
5147 | .PP |
4600 | Care has been taken to ensure that libev does not keep local state inside |
5148 | Care has been taken to ensure that libev does not keep local state inside |
4601 | \&\f(CW\*(C`ev_run\*(C'\fR, and other calls do not usually allow for coroutine switches as |
5149 | \&\f(CW\*(C`ev_run\*(C'\fR, and other calls do not usually allow for coroutine switches as |
4602 | they do not call any callbacks. |
5150 | they do not call any callbacks. |
4603 | .SS "\s-1COMPILER\s0 \s-1WARNINGS\s0" |
5151 | .SS "\s-1COMPILER WARNINGS\s0" |
4604 | .IX Subsection "COMPILER WARNINGS" |
5152 | .IX Subsection "COMPILER WARNINGS" |
4605 | Depending on your compiler and compiler settings, you might get no or a |
5153 | Depending on your compiler and compiler settings, you might get no or a |
4606 | lot of warnings when compiling libev code. Some people are apparently |
5154 | lot of warnings when compiling libev code. Some people are apparently |
4607 | scared by this. |
5155 | scared by this. |
4608 | .PP |
5156 | .PP |
… | |
… | |
4660 | .PP |
5208 | .PP |
4661 | If you need, for some reason, empty reports from valgrind for your project |
5209 | If you need, for some reason, empty reports from valgrind for your project |
4662 | I suggest using suppression lists. |
5210 | I suggest using suppression lists. |
4663 | .SH "PORTABILITY NOTES" |
5211 | .SH "PORTABILITY NOTES" |
4664 | .IX Header "PORTABILITY NOTES" |
5212 | .IX Header "PORTABILITY NOTES" |
4665 | .SS "\s-1GNU/LINUX\s0 32 \s-1BIT\s0 \s-1LIMITATIONS\s0" |
5213 | .SS "\s-1GNU/LINUX 32 BIT LIMITATIONS\s0" |
4666 | .IX Subsection "GNU/LINUX 32 BIT LIMITATIONS" |
5214 | .IX Subsection "GNU/LINUX 32 BIT LIMITATIONS" |
4667 | GNU/Linux is the only common platform that supports 64 bit file/large file |
5215 | GNU/Linux is the only common platform that supports 64 bit file/large file |
4668 | interfaces but \fIdisables\fR them by default. |
5216 | interfaces but \fIdisables\fR them by default. |
4669 | .PP |
5217 | .PP |
4670 | That means that libev compiled in the default environment doesn't support |
5218 | That means that libev compiled in the default environment doesn't support |
4671 | files larger than 2GiB or so, which mainly affects \f(CW\*(C`ev_stat\*(C'\fR watchers. |
5219 | files larger than 2GiB or so, which mainly affects \f(CW\*(C`ev_stat\*(C'\fR watchers. |
4672 | .PP |
5220 | .PP |
4673 | Unfortunately, many programs try to work around this GNU/Linux issue |
5221 | Unfortunately, many programs try to work around this GNU/Linux issue |
4674 | by enabling the large file \s-1API\s0, which makes them incompatible with the |
5222 | by enabling the large file \s-1API,\s0 which makes them incompatible with the |
4675 | standard libev compiled for their system. |
5223 | standard libev compiled for their system. |
4676 | .PP |
5224 | .PP |
4677 | Likewise, libev cannot enable the large file \s-1API\s0 itself as this would |
5225 | Likewise, libev cannot enable the large file \s-1API\s0 itself as this would |
4678 | suddenly make it incompatible to the default compile time environment, |
5226 | suddenly make it incompatible to the default compile time environment, |
4679 | i.e. all programs not using special compile switches. |
5227 | i.e. all programs not using special compile switches. |
4680 | .SS "\s-1OS/X\s0 \s-1AND\s0 \s-1DARWIN\s0 \s-1BUGS\s0" |
5228 | .SS "\s-1OS/X AND DARWIN BUGS\s0" |
4681 | .IX Subsection "OS/X AND DARWIN BUGS" |
5229 | .IX Subsection "OS/X AND DARWIN BUGS" |
4682 | The whole thing is a bug if you ask me \- basically any system interface |
5230 | The whole thing is a bug if you ask me \- basically any system interface |
4683 | you touch is broken, whether it is locales, poll, kqueue or even the |
5231 | you touch is broken, whether it is locales, poll, kqueue or even the |
4684 | OpenGL drivers. |
5232 | OpenGL drivers. |
4685 | .PP |
5233 | .PP |
… | |
… | |
4707 | .PP |
5255 | .PP |
4708 | \fI\f(CI\*(C`select\*(C'\fI is buggy\fR |
5256 | \fI\f(CI\*(C`select\*(C'\fI is buggy\fR |
4709 | .IX Subsection "select is buggy" |
5257 | .IX Subsection "select is buggy" |
4710 | .PP |
5258 | .PP |
4711 | All that's left is \f(CW\*(C`select\*(C'\fR, and of course Apple found a way to fuck this |
5259 | All that's left is \f(CW\*(C`select\*(C'\fR, and of course Apple found a way to fuck this |
4712 | one up as well: On \s-1OS/X\s0, \f(CW\*(C`select\*(C'\fR actively limits the number of file |
5260 | one up as well: On \s-1OS/X, \s0\f(CW\*(C`select\*(C'\fR actively limits the number of file |
4713 | descriptors you can pass in to 1024 \- your program suddenly crashes when |
5261 | descriptors you can pass in to 1024 \- your program suddenly crashes when |
4714 | you use more. |
5262 | you use more. |
4715 | .PP |
5263 | .PP |
4716 | There is an undocumented \*(L"workaround\*(R" for this \- defining |
5264 | There is an undocumented \*(L"workaround\*(R" for this \- defining |
4717 | \&\f(CW\*(C`_DARWIN_UNLIMITED_SELECT\*(C'\fR, which libev tries to use, so select \fIshould\fR |
5265 | \&\f(CW\*(C`_DARWIN_UNLIMITED_SELECT\*(C'\fR, which libev tries to use, so select \fIshould\fR |
4718 | work on \s-1OS/X\s0. |
5266 | work on \s-1OS/X.\s0 |
4719 | .SS "\s-1SOLARIS\s0 \s-1PROBLEMS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" |
5267 | .SS "\s-1SOLARIS PROBLEMS AND WORKAROUNDS\s0" |
4720 | .IX Subsection "SOLARIS PROBLEMS AND WORKAROUNDS" |
5268 | .IX Subsection "SOLARIS PROBLEMS AND WORKAROUNDS" |
4721 | \fI\f(CI\*(C`errno\*(C'\fI reentrancy\fR |
5269 | \fI\f(CI\*(C`errno\*(C'\fI reentrancy\fR |
4722 | .IX Subsection "errno reentrancy" |
5270 | .IX Subsection "errno reentrancy" |
4723 | .PP |
5271 | .PP |
4724 | The default compile environment on Solaris is unfortunately so |
5272 | The default compile environment on Solaris is unfortunately so |
… | |
… | |
4741 | great. |
5289 | great. |
4742 | .PP |
5290 | .PP |
4743 | If you can't get it to work, you can try running the program by setting |
5291 | If you can't get it to work, you can try running the program by setting |
4744 | the environment variable \f(CW\*(C`LIBEV_FLAGS=3\*(C'\fR to only allow \f(CW\*(C`poll\*(C'\fR and |
5292 | the environment variable \f(CW\*(C`LIBEV_FLAGS=3\*(C'\fR to only allow \f(CW\*(C`poll\*(C'\fR and |
4745 | \&\f(CW\*(C`select\*(C'\fR backends. |
5293 | \&\f(CW\*(C`select\*(C'\fR backends. |
4746 | .SS "\s-1AIX\s0 \s-1POLL\s0 \s-1BUG\s0" |
5294 | .SS "\s-1AIX POLL BUG\s0" |
4747 | .IX Subsection "AIX POLL BUG" |
5295 | .IX Subsection "AIX POLL BUG" |
4748 | \&\s-1AIX\s0 unfortunately has a broken \f(CW\*(C`poll.h\*(C'\fR header. Libev works around |
5296 | \&\s-1AIX\s0 unfortunately has a broken \f(CW\*(C`poll.h\*(C'\fR header. Libev works around |
4749 | this by trying to avoid the poll backend altogether (i.e. it's not even |
5297 | this by trying to avoid the poll backend altogether (i.e. it's not even |
4750 | compiled in), which normally isn't a big problem as \f(CW\*(C`select\*(C'\fR works fine |
5298 | compiled in), which normally isn't a big problem as \f(CW\*(C`select\*(C'\fR works fine |
4751 | with large bitsets on \s-1AIX\s0, and \s-1AIX\s0 is dead anyway. |
5299 | with large bitsets on \s-1AIX,\s0 and \s-1AIX\s0 is dead anyway. |
4752 | .SS "\s-1WIN32\s0 \s-1PLATFORM\s0 \s-1LIMITATIONS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" |
5300 | .SS "\s-1WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS\s0" |
4753 | .IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS" |
5301 | .IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS" |
4754 | \fIGeneral issues\fR |
5302 | \fIGeneral issues\fR |
4755 | .IX Subsection "General issues" |
5303 | .IX Subsection "General issues" |
4756 | .PP |
5304 | .PP |
4757 | Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev |
5305 | Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev |
4758 | requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 |
5306 | requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 |
4759 | model. Libev still offers limited functionality on this platform in |
5307 | model. Libev still offers limited functionality on this platform in |
4760 | the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket |
5308 | the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket |
4761 | descriptors. This only applies when using Win32 natively, not when using |
5309 | descriptors. This only applies when using Win32 natively, not when using |
4762 | e.g. cygwin. Actually, it only applies to the microsofts own compilers, |
5310 | e.g. cygwin. Actually, it only applies to the microsofts own compilers, |
4763 | as every compielr comes with a slightly differently broken/incompatible |
5311 | as every compiler comes with a slightly differently broken/incompatible |
4764 | environment. |
5312 | environment. |
4765 | .PP |
5313 | .PP |
4766 | Lifting these limitations would basically require the full |
5314 | Lifting these limitations would basically require the full |
4767 | re-implementation of the I/O system. If you are into this kind of thing, |
5315 | re-implementation of the I/O system. If you are into this kind of thing, |
4768 | then note that glib does exactly that for you in a very portable way (note |
5316 | then note that glib does exactly that for you in a very portable way (note |
… | |
… | |
4826 | \& #define EV_USE_SELECT 1 |
5374 | \& #define EV_USE_SELECT 1 |
4827 | \& #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
5375 | \& #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
4828 | .Ve |
5376 | .Ve |
4829 | .PP |
5377 | .PP |
4830 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
5378 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
4831 | complexity in the O(nA\*^X) range when using win32. |
5379 | complexity in the O(nX) range when using win32. |
4832 | .PP |
5380 | .PP |
4833 | \fILimited number of file descriptors\fR |
5381 | \fILimited number of file descriptors\fR |
4834 | .IX Subsection "Limited number of file descriptors" |
5382 | .IX Subsection "Limited number of file descriptors" |
4835 | .PP |
5383 | .PP |
4836 | Windows has numerous arbitrary (and low) limits on things. |
5384 | Windows has numerous arbitrary (and low) limits on things. |
… | |
… | |
4852 | by calling \f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR |
5400 | by calling \f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR |
4853 | (another arbitrary limit), but is broken in many versions of the Microsoft |
5401 | (another arbitrary limit), but is broken in many versions of the Microsoft |
4854 | runtime libraries. This might get you to about \f(CW512\fR or \f(CW2048\fR sockets |
5402 | runtime libraries. This might get you to about \f(CW512\fR or \f(CW2048\fR sockets |
4855 | (depending on windows version and/or the phase of the moon). To get more, |
5403 | (depending on windows version and/or the phase of the moon). To get more, |
4856 | you need to wrap all I/O functions and provide your own fd management, but |
5404 | you need to wrap all I/O functions and provide your own fd management, but |
4857 | the cost of calling select (O(nA\*^X)) will likely make this unworkable. |
5405 | the cost of calling select (O(nX)) will likely make this unworkable. |
4858 | .SS "\s-1PORTABILITY\s0 \s-1REQUIREMENTS\s0" |
5406 | .SS "\s-1PORTABILITY REQUIREMENTS\s0" |
4859 | .IX Subsection "PORTABILITY REQUIREMENTS" |
5407 | .IX Subsection "PORTABILITY REQUIREMENTS" |
4860 | In addition to a working ISO-C implementation and of course the |
5408 | In addition to a working ISO-C implementation and of course the |
4861 | backend-specific APIs, libev relies on a few additional extensions: |
5409 | backend-specific APIs, libev relies on a few additional extensions: |
4862 | .ie n .IP """void (*)(ev_watcher_type *, int revents)"" must have compatible calling conventions regardless of ""ev_watcher_type *""." 4 |
5410 | .ie n .IP """void (*)(ev_watcher_type *, int revents)"" must have compatible calling conventions regardless of ""ev_watcher_type *""." 4 |
4863 | .el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4 |
5411 | .el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4 |
4864 | .IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *." |
5412 | .IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *." |
4865 | Libev assumes not only that all watcher pointers have the same internal |
5413 | Libev assumes not only that all watcher pointers have the same internal |
4866 | structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO\s0 C for example), but it also |
5414 | structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO C\s0 for example), but it also |
4867 | assumes that the same (machine) code can be used to call any watcher |
5415 | assumes that the same (machine) code can be used to call any watcher |
4868 | callback: The watcher callbacks have different type signatures, but libev |
5416 | callback: The watcher callbacks have different type signatures, but libev |
4869 | calls them using an \f(CW\*(C`ev_watcher *\*(C'\fR internally. |
5417 | calls them using an \f(CW\*(C`ev_watcher *\*(C'\fR internally. |
|
|
5418 | .IP "null pointers and integer zero are represented by 0 bytes" 4 |
|
|
5419 | .IX Item "null pointers and integer zero are represented by 0 bytes" |
|
|
5420 | Libev uses \f(CW\*(C`memset\*(C'\fR to initialise structs and arrays to \f(CW0\fR bytes, and |
|
|
5421 | relies on this setting pointers and integers to null. |
4870 | .IP "pointer accesses must be thread-atomic" 4 |
5422 | .IP "pointer accesses must be thread-atomic" 4 |
4871 | .IX Item "pointer accesses must be thread-atomic" |
5423 | .IX Item "pointer accesses must be thread-atomic" |
4872 | Accessing a pointer value must be atomic, it must both be readable and |
5424 | Accessing a pointer value must be atomic, it must both be readable and |
4873 | writable in one piece \- this is the case on all current architectures. |
5425 | writable in one piece \- this is the case on all current architectures. |
4874 | .ie n .IP """sig_atomic_t volatile"" must be thread-atomic as well" 4 |
5426 | .ie n .IP """sig_atomic_t volatile"" must be thread-atomic as well" 4 |
… | |
… | |
4887 | thread\*(R" or will block signals process-wide, both behaviours would |
5439 | thread\*(R" or will block signals process-wide, both behaviours would |
4888 | be compatible with libev. Interaction between \f(CW\*(C`sigprocmask\*(C'\fR and |
5440 | be compatible with libev. Interaction between \f(CW\*(C`sigprocmask\*(C'\fR and |
4889 | \&\f(CW\*(C`pthread_sigmask\*(C'\fR could complicate things, however. |
5441 | \&\f(CW\*(C`pthread_sigmask\*(C'\fR could complicate things, however. |
4890 | .Sp |
5442 | .Sp |
4891 | The most portable way to handle signals is to block signals in all threads |
5443 | The most portable way to handle signals is to block signals in all threads |
4892 | except the initial one, and run the default loop in the initial thread as |
5444 | except the initial one, and run the signal handling loop in the initial |
4893 | well. |
5445 | thread as well. |
4894 | .ie n .IP """long"" must be large enough for common memory allocation sizes" 4 |
5446 | .ie n .IP """long"" must be large enough for common memory allocation sizes" 4 |
4895 | .el .IP "\f(CWlong\fR must be large enough for common memory allocation sizes" 4 |
5447 | .el .IP "\f(CWlong\fR must be large enough for common memory allocation sizes" 4 |
4896 | .IX Item "long must be large enough for common memory allocation sizes" |
5448 | .IX Item "long must be large enough for common memory allocation sizes" |
4897 | To improve portability and simplify its \s-1API\s0, libev uses \f(CW\*(C`long\*(C'\fR internally |
5449 | To improve portability and simplify its \s-1API,\s0 libev uses \f(CW\*(C`long\*(C'\fR internally |
4898 | instead of \f(CW\*(C`size_t\*(C'\fR when allocating its data structures. On non-POSIX |
5450 | instead of \f(CW\*(C`size_t\*(C'\fR when allocating its data structures. On non-POSIX |
4899 | systems (Microsoft...) this might be unexpectedly low, but is still at |
5451 | systems (Microsoft...) this might be unexpectedly low, but is still at |
4900 | least 31 bits everywhere, which is enough for hundreds of millions of |
5452 | least 31 bits everywhere, which is enough for hundreds of millions of |
4901 | watchers. |
5453 | watchers. |
4902 | .ie n .IP """double"" must hold a time value in seconds with enough accuracy" 4 |
5454 | .ie n .IP """double"" must hold a time value in seconds with enough accuracy" 4 |
… | |
… | |
4904 | .IX Item "double must hold a time value in seconds with enough accuracy" |
5456 | .IX Item "double must hold a time value in seconds with enough accuracy" |
4905 | The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to |
5457 | The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to |
4906 | have at least 51 bits of mantissa (and 9 bits of exponent), which is |
5458 | have at least 51 bits of mantissa (and 9 bits of exponent), which is |
4907 | good enough for at least into the year 4000 with millisecond accuracy |
5459 | good enough for at least into the year 4000 with millisecond accuracy |
4908 | (the design goal for libev). This requirement is overfulfilled by |
5460 | (the design goal for libev). This requirement is overfulfilled by |
4909 | implementations using \s-1IEEE\s0 754, which is basically all existing ones. With |
5461 | implementations using \s-1IEEE 754,\s0 which is basically all existing ones. |
|
|
5462 | .Sp |
4910 | \&\s-1IEEE\s0 754 doubles, you get microsecond accuracy until at least 2200. |
5463 | With \s-1IEEE 754\s0 doubles, you get microsecond accuracy until at least the |
|
|
5464 | year 2255 (and millisecond accuracy till the year 287396 \- by then, libev |
|
|
5465 | is either obsolete or somebody patched it to use \f(CW\*(C`long double\*(C'\fR or |
|
|
5466 | something like that, just kidding). |
4911 | .PP |
5467 | .PP |
4912 | If you know of other additional requirements drop me a note. |
5468 | If you know of other additional requirements drop me a note. |
4913 | .SH "ALGORITHMIC COMPLEXITIES" |
5469 | .SH "ALGORITHMIC COMPLEXITIES" |
4914 | .IX Header "ALGORITHMIC COMPLEXITIES" |
5470 | .IX Header "ALGORITHMIC COMPLEXITIES" |
4915 | In this section the complexities of (many of) the algorithms used inside |
5471 | In this section the complexities of (many of) the algorithms used inside |
… | |
… | |
4969 | .IX Item "Processing ev_async_send: O(number_of_async_watchers)" |
5525 | .IX Item "Processing ev_async_send: O(number_of_async_watchers)" |
4970 | .IP "Processing signals: O(max_signal_number)" 4 |
5526 | .IP "Processing signals: O(max_signal_number)" 4 |
4971 | .IX Item "Processing signals: O(max_signal_number)" |
5527 | .IX Item "Processing signals: O(max_signal_number)" |
4972 | .PD |
5528 | .PD |
4973 | Sending involves a system call \fIiff\fR there were no other \f(CW\*(C`ev_async_send\*(C'\fR |
5529 | Sending involves a system call \fIiff\fR there were no other \f(CW\*(C`ev_async_send\*(C'\fR |
4974 | calls in the current loop iteration. Checking for async and signal events |
5530 | calls in the current loop iteration and the loop is currently |
|
|
5531 | blocked. Checking for async and signal events involves iterating over all |
4975 | involves iterating over all running async watchers or all signal numbers. |
5532 | running async watchers or all signal numbers. |
4976 | .SH "PORTING FROM LIBEV 3.X TO 4.X" |
5533 | .SH "PORTING FROM LIBEV 3.X TO 4.X" |
4977 | .IX Header "PORTING FROM LIBEV 3.X TO 4.X" |
5534 | .IX Header "PORTING FROM LIBEV 3.X TO 4.X" |
4978 | The major version 4 introduced some incompatible changes to the \s-1API\s0. |
5535 | The major version 4 introduced some incompatible changes to the \s-1API.\s0 |
4979 | .PP |
5536 | .PP |
4980 | At the moment, the \f(CW\*(C`ev.h\*(C'\fR header file provides compatibility definitions |
5537 | At the moment, the \f(CW\*(C`ev.h\*(C'\fR header file provides compatibility definitions |
4981 | for all changes, so most programs should still compile. The compatibility |
5538 | for all changes, so most programs should still compile. The compatibility |
4982 | layer might be removed in later versions of libev, so better update to the |
5539 | layer might be removed in later versions of libev, so better update to the |
4983 | new \s-1API\s0 early than late. |
5540 | new \s-1API\s0 early than late. |
4984 | .ie n .IP """EV_COMPAT3"" backwards compatibility mechanism" 4 |
5541 | .ie n .IP """EV_COMPAT3"" backwards compatibility mechanism" 4 |
4985 | .el .IP "\f(CWEV_COMPAT3\fR backwards compatibility mechanism" 4 |
5542 | .el .IP "\f(CWEV_COMPAT3\fR backwards compatibility mechanism" 4 |
4986 | .IX Item "EV_COMPAT3 backwards compatibility mechanism" |
5543 | .IX Item "EV_COMPAT3 backwards compatibility mechanism" |
4987 | The backward compatibility mechanism can be controlled by |
5544 | The backward compatibility mechanism can be controlled by |
4988 | \&\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 |
5545 | \&\f(CW\*(C`EV_COMPAT3\*(C'\fR. See \*(L"\s-1PREPROCESSOR SYMBOLS/MACROS\*(R"\s0 in the \*(L"\s-1EMBEDDING\*(R"\s0 |
4989 | section. |
5546 | section. |
4990 | .ie n .IP """ev_default_destroy"" and ""ev_default_fork"" have been removed" 4 |
5547 | .ie n .IP """ev_default_destroy"" and ""ev_default_fork"" have been removed" 4 |
4991 | .el .IP "\f(CWev_default_destroy\fR and \f(CWev_default_fork\fR have been removed" 4 |
5548 | .el .IP "\f(CWev_default_destroy\fR and \f(CWev_default_fork\fR have been removed" 4 |
4992 | .IX Item "ev_default_destroy and ev_default_fork have been removed" |
5549 | .IX Item "ev_default_destroy and ev_default_fork have been removed" |
4993 | These calls can be replaced easily by their \f(CW\*(C`ev_loop_xxx\*(C'\fR counterparts: |
5550 | These calls can be replaced easily by their \f(CW\*(C`ev_loop_xxx\*(C'\fR counterparts: |
… | |
… | |
5033 | .SH "GLOSSARY" |
5590 | .SH "GLOSSARY" |
5034 | .IX Header "GLOSSARY" |
5591 | .IX Header "GLOSSARY" |
5035 | .IP "active" 4 |
5592 | .IP "active" 4 |
5036 | .IX Item "active" |
5593 | .IX Item "active" |
5037 | A watcher is active as long as it has been started and not yet stopped. |
5594 | A watcher is active as long as it has been started and not yet stopped. |
5038 | See \*(L"\s-1WATCHER\s0 \s-1STATES\s0\*(R" for details. |
5595 | See \*(L"\s-1WATCHER STATES\*(R"\s0 for details. |
5039 | .IP "application" 4 |
5596 | .IP "application" 4 |
5040 | .IX Item "application" |
5597 | .IX Item "application" |
5041 | In this document, an application is whatever is using libev. |
5598 | In this document, an application is whatever is using libev. |
5042 | .IP "backend" 4 |
5599 | .IP "backend" 4 |
5043 | .IX Item "backend" |
5600 | .IX Item "backend" |
… | |
… | |
5070 | The model used to describe how an event loop handles and processes |
5627 | The model used to describe how an event loop handles and processes |
5071 | watchers and events. |
5628 | watchers and events. |
5072 | .IP "pending" 4 |
5629 | .IP "pending" 4 |
5073 | .IX Item "pending" |
5630 | .IX Item "pending" |
5074 | A watcher is pending as soon as the corresponding event has been |
5631 | A watcher is pending as soon as the corresponding event has been |
5075 | detected. See \*(L"\s-1WATCHER\s0 \s-1STATES\s0\*(R" for details. |
5632 | detected. See \*(L"\s-1WATCHER STATES\*(R"\s0 for details. |
5076 | .IP "real time" 4 |
5633 | .IP "real time" 4 |
5077 | .IX Item "real time" |
5634 | .IX Item "real time" |
5078 | The physical time that is observed. It is apparently strictly monotonic :) |
5635 | The physical time that is observed. It is apparently strictly monotonic :) |
5079 | .IP "wall-clock time" 4 |
5636 | .IP "wall-clock time" 4 |
5080 | .IX Item "wall-clock time" |
5637 | .IX Item "wall-clock time" |
5081 | The time and date as shown on clocks. Unlike real time, it can actually |
5638 | The time and date as shown on clocks. Unlike real time, it can actually |
5082 | be wrong and jump forwards and backwards, e.g. when the you adjust your |
5639 | be wrong and jump forwards and backwards, e.g. when you adjust your |
5083 | clock. |
5640 | clock. |
5084 | .IP "watcher" 4 |
5641 | .IP "watcher" 4 |
5085 | .IX Item "watcher" |
5642 | .IX Item "watcher" |
5086 | A data structure that describes interest in certain events. Watchers need |
5643 | A data structure that describes interest in certain events. Watchers need |
5087 | to be started (attached to an event loop) before they can receive events. |
5644 | to be started (attached to an event loop) before they can receive events. |
5088 | .SH "AUTHOR" |
5645 | .SH "AUTHOR" |
5089 | .IX Header "AUTHOR" |
5646 | .IX Header "AUTHOR" |
5090 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael |
5647 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael |
5091 | Magnusson and Emanuele Giaquinta. |
5648 | Magnusson and Emanuele Giaquinta, and minor corrections by many others. |