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126 | .IX Title "LIBEV 3" |
135 | .IX Title "LIBEV 3" |
127 | .TH LIBEV 3 "2011-02-16" "libev-4.04" "libev - high performance full featured event loop" |
136 | .TH LIBEV 3 "2018-12-21" "libev-4.25" "libev - high performance full featured event loop" |
128 | .\" For nroff, turn off justification. Always turn off hyphenation; it makes |
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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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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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508 | .IX Item "EVFLAG_NOENV" |
523 | .IX Item "EVFLAG_NOENV" |
509 | 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 |
510 | 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 |
511 | \&\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 |
512 | 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 |
513 | 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 |
514 | 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). |
515 | .ie n .IP """EVFLAG_FORKCHECK""" 4 |
532 | .ie n .IP """EVFLAG_FORKCHECK""" 4 |
516 | .el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4 |
533 | .el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4 |
517 | .IX Item "EVFLAG_FORKCHECK" |
534 | .IX Item "EVFLAG_FORKCHECK" |
518 | 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 |
519 | 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. |
520 | .Sp |
537 | .Sp |
521 | 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, |
522 | 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 |
523 | 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 |
524 | 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 |
525 | 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 |
526 | \&\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). |
527 | .Sp |
545 | .Sp |
528 | 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 |
529 | forget about forgetting to tell libev about forking) when you use this |
547 | forget about forgetting to tell libev about forking, although you still |
530 | flag. |
548 | have to ignore \f(CW\*(C`SIGPIPE\*(C'\fR) when you use this flag. |
531 | .Sp |
549 | .Sp |
532 | 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 |
533 | environment variable. |
551 | environment variable. |
534 | .ie n .IP """EVFLAG_NOINOTIFY""" 4 |
552 | .ie n .IP """EVFLAG_NOINOTIFY""" 4 |
535 | .el .IP "\f(CWEVFLAG_NOINOTIFY\fR" 4 |
553 | .el .IP "\f(CWEVFLAG_NOINOTIFY\fR" 4 |
… | |
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553 | example) that can't properly initialise their signal masks. |
571 | example) that can't properly initialise their signal masks. |
554 | .ie n .IP """EVFLAG_NOSIGMASK""" 4 |
572 | .ie n .IP """EVFLAG_NOSIGMASK""" 4 |
555 | .el .IP "\f(CWEVFLAG_NOSIGMASK\fR" 4 |
573 | .el .IP "\f(CWEVFLAG_NOSIGMASK\fR" 4 |
556 | .IX Item "EVFLAG_NOSIGMASK" |
574 | .IX Item "EVFLAG_NOSIGMASK" |
557 | When this flag is specified, then libev will avoid to modify the signal |
575 | When this flag is specified, then libev will avoid to modify the signal |
558 | mask. Specifically, this means you ahve to make sure signals are unblocked |
576 | mask. Specifically, this means you have to make sure signals are unblocked |
559 | when you want to receive them. |
577 | when you want to receive them. |
560 | .Sp |
578 | .Sp |
561 | This behaviour is useful when you want to do your own signal handling, or |
579 | This behaviour is useful when you want to do your own signal handling, or |
562 | want to handle signals only in specific threads and want to avoid libev |
580 | want to handle signals only in specific threads and want to avoid libev |
563 | unblocking the signals. |
581 | unblocking the signals. |
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566 | \&\f(CW\*(C`sigprocmask\*(C'\fR, whose behaviour is officially unspecified. |
584 | \&\f(CW\*(C`sigprocmask\*(C'\fR, whose behaviour is officially unspecified. |
567 | .Sp |
585 | .Sp |
568 | This flag's behaviour will become the default in future versions of libev. |
586 | This flag's behaviour will become the default in future versions of libev. |
569 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
587 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
570 | .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 |
571 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
589 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
572 | 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 |
573 | 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, |
574 | 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 |
575 | 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 |
576 | 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. |
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585 | 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 |
586 | \&\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 |
587 | \&\f(CW\*(C`exceptfds\*(C'\fR set on that platform). |
605 | \&\f(CW\*(C`exceptfds\*(C'\fR set on that platform). |
588 | .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 |
589 | .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 |
590 | .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)" |
591 | 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 |
592 | than select, but handles sparse fds better and has no artificial |
610 | than select, but handles sparse fds better and has no artificial |
593 | 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 |
594 | 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, |
595 | 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 |
… | |
… | |
597 | .Sp |
615 | .Sp |
598 | 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 |
599 | \&\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. |
600 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
618 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
601 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
619 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
602 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
620 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
603 | 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 |
604 | kernels). |
622 | kernels). |
605 | .Sp |
623 | .Sp |
606 | 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 |
607 | but it scales phenomenally better. While poll and select usually scale |
625 | it scales phenomenally better. While poll and select usually scale like |
608 | 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 |
609 | epoll scales either O(1) or O(active_fds). |
627 | fd), epoll scales either O(1) or O(active_fds). |
610 | .Sp |
628 | .Sp |
611 | The epoll mechanism deserves honorable mention as the most misdesigned |
629 | The epoll mechanism deserves honorable mention as the most misdesigned |
612 | of the more advanced event mechanisms: mere annoyances include silently |
630 | of the more advanced event mechanisms: mere annoyances include silently |
613 | dropping file descriptors, requiring a system call per change per file |
631 | dropping file descriptors, requiring a system call per change per file |
614 | descriptor (and unnecessary guessing of parameters), problems with dup, |
632 | descriptor (and unnecessary guessing of parameters), problems with dup, |
… | |
… | |
617 | 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 |
618 | 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 |
619 | set, which can take considerable time (one syscall per file descriptor) |
637 | set, which can take considerable time (one syscall per file descriptor) |
620 | and is of course hard to detect. |
638 | and is of course hard to detect. |
621 | .Sp |
639 | .Sp |
622 | Epoll is also notoriously buggy \- embedding epoll fds \fIshould\fR work, but |
640 | Epoll is also notoriously buggy \- embedding epoll fds \fIshould\fR work, |
623 | 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 |
624 | \&\fIdifferent\fR file descriptors (even already closed ones, so one cannot |
642 | totally \fIdifferent\fR file descriptors (even already closed ones, so |
625 | 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 |
626 | 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 |
627 | employing an additional generation counter and comparing that against the |
645 | notifications by employing an additional generation counter and comparing |
628 | 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 |
629 | 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 |
630 | 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...). |
631 | .Sp |
652 | .Sp |
632 | Epoll is truly the train wreck analog among event poll mechanisms, |
653 | Epoll is truly the train wreck among event poll mechanisms, a frankenpoll, |
633 | a frankenpoll, cobbled together in a hurry, no thought to design or |
654 | cobbled together in a hurry, no thought to design or interaction with |
634 | interaction with others. |
655 | others. Oh, the pain, will it ever stop... |
635 | .Sp |
656 | .Sp |
636 | 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 |
637 | 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 |
638 | 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 |
639 | \&\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 |
… | |
… | |
657 | .Sp |
678 | .Sp |
658 | 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 |
659 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
680 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
660 | .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 |
661 | .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 |
662 | .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" |
683 | .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" |
663 | 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 |
664 | 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 |
665 | 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 |
666 | it's completely useless). Unlike epoll, however, whose brokenness |
687 | it's completely useless). Unlike epoll, however, whose brokenness |
667 | 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 |
… | |
… | |
676 | .Sp |
697 | .Sp |
677 | 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 |
678 | 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 |
679 | 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 |
680 | 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 |
681 | 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 |
682 | 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 |
683 | cases |
704 | drops fds silently in similarly hard-to-detect cases. |
684 | .Sp |
705 | .Sp |
685 | This backend usually performs well under most conditions. |
706 | This backend usually performs well under most conditions. |
686 | .Sp |
707 | .Sp |
687 | While nominally embeddable in other event loops, this doesn't work |
708 | While nominally embeddable in other event loops, this doesn't work |
688 | 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 |
689 | 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 |
690 | (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 |
691 | (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 |
692 | 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. |
693 | .Sp |
714 | .Sp |
694 | 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 |
695 | \&\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 |
696 | \&\f(CW\*(C`NOTE_EOF\*(C'\fR. |
717 | \&\f(CW\*(C`NOTE_EOF\*(C'\fR. |
697 | .ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 |
718 | .ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 |
… | |
… | |
701 | 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 |
702 | 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 |
703 | immensely. |
724 | immensely. |
704 | .ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 |
725 | .ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 |
705 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
726 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
706 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
727 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
707 | 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, |
708 | 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)). |
709 | .Sp |
730 | .Sp |
710 | 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 |
711 | 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 |
… | |
… | |
717 | among the OS-specific backends (I vastly prefer correctness over speed |
738 | among the OS-specific backends (I vastly prefer correctness over speed |
718 | hacks). |
739 | hacks). |
719 | .Sp |
740 | .Sp |
720 | On the negative side, the interface is \fIbizarre\fR \- so bizarre that |
741 | On the negative side, the interface is \fIbizarre\fR \- so bizarre that |
721 | even sun itself gets it wrong in their code examples: The event polling |
742 | even sun itself gets it wrong in their code examples: The event polling |
722 | function sometimes returning events to the caller even though an error |
743 | function sometimes returns events to the caller even though an error |
723 | occurred, but with no indication whether it has done so or not (yes, it's |
744 | occurred, but with no indication whether it has done so or not (yes, it's |
724 | even documented that way) \- deadly for edge-triggered interfaces where |
745 | even documented that way) \- deadly for edge-triggered interfaces where you |
725 | you absolutely have to know whether an event occurred or not because you |
746 | absolutely have to know whether an event occurred or not because you have |
726 | have to re-arm the watcher. |
747 | to re-arm the watcher. |
727 | .Sp |
748 | .Sp |
728 | Fortunately libev seems to be able to work around these idiocies. |
749 | Fortunately libev seems to be able to work around these idiocies. |
729 | .Sp |
750 | .Sp |
730 | 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 |
731 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
752 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
… | |
… | |
790 | 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. |
791 | 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 |
792 | and \f(CW\*(C`ev_loop_destroy\*(C'\fR. |
813 | and \f(CW\*(C`ev_loop_destroy\*(C'\fR. |
793 | .IP "ev_loop_fork (loop)" 4 |
814 | .IP "ev_loop_fork (loop)" 4 |
794 | .IX Item "ev_loop_fork (loop)" |
815 | .IX Item "ev_loop_fork (loop)" |
795 | 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 |
796 | reinitialise the kernel state for backends that have one. Despite the |
817 | to reinitialise the kernel state for backends that have one. Despite |
797 | 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 |
798 | 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 |
799 | 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. |
800 | .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 |
801 | 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 |
802 | 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 |
803 | because some kernel interfaces *cough* \fIkqueue\fR *cough* do funny things |
828 | because some kernel interfaces *cough* \fIkqueue\fR *cough* do funny things |
804 | during fork. |
829 | during fork. |
805 | .Sp |
830 | .Sp |
806 | 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 |
… | |
… | |
900 | 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 |
901 | 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. |
902 | .Sp |
927 | .Sp |
903 | 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 |
904 | 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). |
905 | .IP "ev_run (loop, int flags)" 4 |
930 | .IP "bool ev_run (loop, int flags)" 4 |
906 | .IX Item "ev_run (loop, int flags)" |
931 | .IX Item "bool ev_run (loop, int flags)" |
907 | 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 |
908 | 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 |
909 | 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 |
910 | the watcher callbacks, an then repeat the whole process indefinitely: This |
935 | the watcher callbacks, and then repeat the whole process indefinitely: This |
911 | is why event loops are called \fIloops\fR. |
936 | is why event loops are called \fIloops\fR. |
912 | .Sp |
937 | .Sp |
913 | 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 |
914 | 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 |
915 | 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"). |
916 | .Sp |
945 | .Sp |
917 | 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 |
918 | 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 |
919 | finished (especially in interactive programs), but having a program |
948 | finished (especially in interactive programs), but having a program |
920 | 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 |
921 | 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 |
922 | beauty. |
951 | beauty. |
923 | .Sp |
952 | .Sp |
924 | This function is also \fImostly\fR exception-safe \- you can break out of |
953 | This function is \fImostly\fR exception-safe \- you can break out of a |
925 | a \f(CW\*(C`ev_run\*(C'\fR call by calling \f(CW\*(C`longjmp\*(C'\fR in a callback, throwing a \*(C+ |
954 | \&\f(CW\*(C`ev_run\*(C'\fR call by calling \f(CW\*(C`longjmp\*(C'\fR in a callback, throwing a \*(C+ |
926 | exception and so on. This does not decrement the \f(CW\*(C`ev_depth\*(C'\fR value, nor |
955 | exception and so on. This does not decrement the \f(CW\*(C`ev_depth\*(C'\fR value, nor |
927 | will it clear any outstanding \f(CW\*(C`EVBREAK_ONE\*(C'\fR breaks. |
956 | will it clear any outstanding \f(CW\*(C`EVBREAK_ONE\*(C'\fR breaks. |
928 | .Sp |
957 | .Sp |
929 | 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 |
930 | 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 |
… | |
… | |
942 | 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 |
943 | 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 |
944 | 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 |
945 | usually a better approach for this kind of thing. |
974 | usually a better approach for this kind of thing. |
946 | .Sp |
975 | .Sp |
947 | 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): |
948 | .Sp |
979 | .Sp |
949 | .Vb 10 |
980 | .Vb 10 |
950 | \& \- Increment loop depth. |
981 | \& \- Increment loop depth. |
951 | \& \- Reset the ev_break status. |
982 | \& \- Reset the ev_break status. |
952 | \& \- Before the first iteration, call any pending watchers. |
983 | \& \- Before the first iteration, call any pending watchers. |
… | |
… | |
1067 | 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. |
1068 | .Sp |
1099 | .Sp |
1069 | 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 |
1070 | 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, |
1071 | 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 |
1072 | \&\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 |
1073 | 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 |
1074 | 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 |
1075 | once per this interval, on average. |
1106 | once per this interval, on average (as long as the host time resolution is |
|
|
1107 | good enough). |
1076 | .Sp |
1108 | .Sp |
1077 | 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 |
1078 | to spend more time collecting timeouts, at the expense of increased |
1110 | to spend more time collecting timeouts, at the expense of increased |
1079 | latency/jitter/inexactness (the watcher callback will be called |
1111 | latency/jitter/inexactness (the watcher callback will be called |
1080 | 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 |
… | |
… | |
1124 | 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 |
1125 | invoke the actual watchers inside another context (another thread etc.). |
1157 | invoke the actual watchers inside another context (another thread etc.). |
1126 | .Sp |
1158 | .Sp |
1127 | 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 |
1128 | callback. |
1160 | callback. |
1129 | .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 |
1130 | .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 ())" |
1131 | 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 |
1132 | 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 |
1133 | each call to a libev function. |
1165 | each call to a libev function. |
1134 | .Sp |
1166 | .Sp |
1135 | 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 |
1136 | 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 |
1137 | 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 |
1138 | \&\fIrelease\fR and \fIacquire\fR callbacks on the loop. |
1170 | \&\fIrelease\fR and \fIacquire\fR callbacks on the loop. |
1139 | .Sp |
1171 | .Sp |
1140 | 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 |
1141 | 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 |
1142 | afterwards. |
1174 | afterwards. |
… | |
… | |
1283 | .PD 0 |
1315 | .PD 0 |
1284 | .ie n .IP """EV_CHECK""" 4 |
1316 | .ie n .IP """EV_CHECK""" 4 |
1285 | .el .IP "\f(CWEV_CHECK\fR" 4 |
1317 | .el .IP "\f(CWEV_CHECK\fR" 4 |
1286 | .IX Item "EV_CHECK" |
1318 | .IX Item "EV_CHECK" |
1287 | .PD |
1319 | .PD |
1288 | 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 |
1289 | 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) |
1290 | \&\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 |
1291 | 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 |
1292 | 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 |
1293 | (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 |
1294 | \&\f(CW\*(C`ev_run\*(C'\fR from blocking). |
1331 | blocking). |
1295 | .ie n .IP """EV_EMBED""" 4 |
1332 | .ie n .IP """EV_EMBED""" 4 |
1296 | .el .IP "\f(CWEV_EMBED\fR" 4 |
1333 | .el .IP "\f(CWEV_EMBED\fR" 4 |
1297 | .IX Item "EV_EMBED" |
1334 | .IX Item "EV_EMBED" |
1298 | 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. |
1299 | .ie n .IP """EV_FORK""" 4 |
1336 | .ie n .IP """EV_FORK""" 4 |
… | |
… | |
1331 | 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 |
1332 | 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 |
1333 | 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 |
1334 | 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 |
1335 | thing, so beware. |
1372 | thing, so beware. |
1336 | .SS "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0" |
1373 | .SS "\s-1GENERIC WATCHER FUNCTIONS\s0" |
1337 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
1374 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
1338 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
1375 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
1339 | .el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 |
1376 | .el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 |
1340 | .IX Item "ev_init (ev_TYPE *watcher, callback)" |
1377 | .IX Item "ev_init (ev_TYPE *watcher, callback)" |
1341 | This macro initialises the generic portion of a watcher. The contents |
1378 | This macro initialises the generic portion of a watcher. The contents |
… | |
… | |
1420 | 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 |
1421 | it). |
1458 | it). |
1422 | .IP "callback ev_cb (ev_TYPE *watcher)" 4 |
1459 | .IP "callback ev_cb (ev_TYPE *watcher)" 4 |
1423 | .IX Item "callback ev_cb (ev_TYPE *watcher)" |
1460 | .IX Item "callback ev_cb (ev_TYPE *watcher)" |
1424 | Returns the callback currently set on the watcher. |
1461 | Returns the callback currently set on the watcher. |
1425 | .IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 |
1462 | .IP "ev_set_cb (ev_TYPE *watcher, callback)" 4 |
1426 | .IX Item "ev_cb_set (ev_TYPE *watcher, callback)" |
1463 | .IX Item "ev_set_cb (ev_TYPE *watcher, callback)" |
1427 | 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 |
1428 | (modulo threads). |
1465 | (modulo threads). |
1429 | .IP "ev_set_priority (ev_TYPE *watcher, int priority)" 4 |
1466 | .IP "ev_set_priority (ev_TYPE *watcher, int priority)" 4 |
1430 | .IX Item "ev_set_priority (ev_TYPE *watcher, int priority)" |
1467 | .IX Item "ev_set_priority (ev_TYPE *watcher, int priority)" |
1431 | .PD 0 |
1468 | .PD 0 |
… | |
… | |
1449 | or might not have been clamped to the valid range. |
1486 | or might not have been clamped to the valid range. |
1450 | .Sp |
1487 | .Sp |
1451 | 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 |
1452 | 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 :). |
1453 | .Sp |
1490 | .Sp |
1454 | 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 |
1455 | priorities. |
1492 | priorities. |
1456 | .IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4 |
1493 | .IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4 |
1457 | .IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)" |
1494 | .IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)" |
1458 | 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 |
1459 | \&\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 |
… | |
… | |
1479 | not started in the first place. |
1516 | not started in the first place. |
1480 | .Sp |
1517 | .Sp |
1481 | 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 |
1482 | functions that do not need a watcher. |
1519 | functions that do not need a watcher. |
1483 | .PP |
1520 | .PP |
1484 | See also the \*(L"\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0\*(R" and \*(L"\s-1BUILDING\s0 \s-1YOUR\s0 |
1521 | See also the \*(L"\s-1ASSOCIATING CUSTOM DATA WITH A WATCHER\*(R"\s0 and \*(L"\s-1BUILDING YOUR |
1485 | \&\s-1OWN\s0 \s-1COMPOSITE\s0 \s-1WATCHERS\s0\*(R" idioms. |
1522 | OWN COMPOSITE WATCHERS\*(R"\s0 idioms. |
1486 | .SS "\s-1WATCHER\s0 \s-1STATES\s0" |
1523 | .SS "\s-1WATCHER STATES\s0" |
1487 | .IX Subsection "WATCHER STATES" |
1524 | .IX Subsection "WATCHER STATES" |
1488 | There are various watcher states mentioned throughout this manual \- |
1525 | There are various watcher states mentioned throughout this manual \- |
1489 | 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 |
1490 | 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 |
1491 | 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". |
1492 | .IP "initialiased" 4 |
1529 | .IP "initialised" 4 |
1493 | .IX Item "initialiased" |
1530 | .IX Item "initialised" |
1494 | 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 |
1495 | 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 |
1496 | \&\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. |
1497 | .Sp |
1534 | .Sp |
1498 | In this state it is simply some block of memory that is suitable for |
1535 | In this state it is simply some block of memory that is suitable for |
1499 | use in an event loop. It can be moved around, freed, reused etc. at |
1536 | use in an event loop. It can be moved around, freed, reused etc. at |
… | |
… | |
1534 | .Sp |
1571 | .Sp |
1535 | While stopped (and not pending) the watcher is essentially in the |
1572 | While stopped (and not pending) the watcher is essentially in the |
1536 | 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 |
1537 | you wish (but when you trash the memory block, you need to \f(CW\*(C`ev_TYPE_init\*(C'\fR |
1574 | you wish (but when you trash the memory block, you need to \f(CW\*(C`ev_TYPE_init\*(C'\fR |
1538 | it again). |
1575 | it again). |
1539 | .SS "\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0" |
1576 | .SS "\s-1WATCHER PRIORITY MODELS\s0" |
1540 | .IX Subsection "WATCHER PRIORITY MODELS" |
1577 | .IX Subsection "WATCHER PRIORITY MODELS" |
1541 | Many event loops support \fIwatcher priorities\fR, which are usually small |
1578 | Many event loops support \fIwatcher priorities\fR, which are usually small |
1542 | integers that influence the ordering of event callback invocation |
1579 | integers that influence the ordering of event callback invocation |
1543 | between watchers in some way, all else being equal. |
1580 | between watchers in some way, all else being equal. |
1544 | .PP |
1581 | .PP |
… | |
… | |
1742 | wish to read \- you would first have to request some data. |
1779 | wish to read \- you would first have to request some data. |
1743 | .PP |
1780 | .PP |
1744 | Since files are typically not-so-well supported by advanced notification |
1781 | Since files are typically not-so-well supported by advanced notification |
1745 | mechanism, libev tries hard to emulate \s-1POSIX\s0 behaviour with respect |
1782 | mechanism, libev tries hard to emulate \s-1POSIX\s0 behaviour with respect |
1746 | to files, even though you should not use it. The reason for this is |
1783 | to files, even though you should not use it. The reason for this is |
1747 | convenience: sometimes you want to watch \s-1STDIN\s0 or \s-1STDOUT\s0, which is |
1784 | convenience: sometimes you want to watch \s-1STDIN\s0 or \s-1STDOUT,\s0 which is |
1748 | usually a tty, often a pipe, but also sometimes files or special devices |
1785 | usually a tty, often a pipe, but also sometimes files or special devices |
1749 | (for example, \f(CW\*(C`epoll\*(C'\fR on Linux works with \fI/dev/random\fR but not with |
1786 | (for example, \f(CW\*(C`epoll\*(C'\fR on Linux works with \fI/dev/random\fR but not with |
1750 | \&\fI/dev/urandom\fR), and even though the file might better be served with |
1787 | \&\fI/dev/urandom\fR), and even though the file might better be served with |
1751 | asynchronous I/O instead of with non-blocking I/O, it is still useful when |
1788 | asynchronous I/O instead of with non-blocking I/O, it is still useful when |
1752 | it \*(L"just works\*(R" instead of freezing. |
1789 | it \*(L"just works\*(R" instead of freezing. |
1753 | .PP |
1790 | .PP |
1754 | So avoid file descriptors pointing to files when you know it (e.g. use |
1791 | So avoid file descriptors pointing to files when you know it (e.g. use |
1755 | libeio), but use them when it is convenient, e.g. for \s-1STDIN/STDOUT\s0, or |
1792 | libeio), but use them when it is convenient, e.g. for \s-1STDIN/STDOUT,\s0 or |
1756 | when you rarely read from a file instead of from a socket, and want to |
1793 | when you rarely read from a file instead of from a socket, and want to |
1757 | reuse the same code path. |
1794 | reuse the same code path. |
1758 | .PP |
1795 | .PP |
1759 | \fIThe special problem of fork\fR |
1796 | \fIThe special problem of fork\fR |
1760 | .IX Subsection "The special problem of fork" |
1797 | .IX Subsection "The special problem of fork" |
… | |
… | |
1770 | \fIThe special problem of \s-1SIGPIPE\s0\fR |
1807 | \fIThe special problem of \s-1SIGPIPE\s0\fR |
1771 | .IX Subsection "The special problem of SIGPIPE" |
1808 | .IX Subsection "The special problem of SIGPIPE" |
1772 | .PP |
1809 | .PP |
1773 | 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: |
1774 | 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 |
1775 | 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 |
1776 | this is sensible behaviour, for daemons, this is usually undesirable. |
1813 | this is sensible behaviour, for daemons, this is usually undesirable. |
1777 | .PP |
1814 | .PP |
1778 | So when you encounter spurious, unexplained daemon exits, make sure you |
1815 | So when you encounter spurious, unexplained daemon exits, make sure you |
1779 | 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 |
1780 | somewhere, as that would have given you a big clue). |
1817 | somewhere, as that would have given you a big clue). |
1781 | .PP |
1818 | .PP |
1782 | \fIThe special problem of \fIaccept()\fIing when you can't\fR |
1819 | \fIThe special problem of \fIaccept()\fIing when you can't\fR |
1783 | .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" |
1784 | .PP |
1821 | .PP |
1785 | 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, |
1786 | 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 |
1787 | connection from the pending queue in all error cases. |
1824 | connection from the pending queue in all error cases. |
1788 | .PP |
1825 | .PP |
1789 | For example, larger servers often run out of file descriptors (because |
1826 | For example, larger servers often run out of file descriptors (because |
1790 | 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 |
… | |
… | |
1871 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1908 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1872 | monotonic clock option helps a lot here). |
1909 | monotonic clock option helps a lot here). |
1873 | .PP |
1910 | .PP |
1874 | 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 |
1875 | 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 |
1876 | 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 |
1877 | 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 |
1878 | 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 |
1879 | 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). |
1880 | .PP |
1918 | .PP |
1881 | \fIBe smart about timeouts\fR |
1919 | \fIBe smart about timeouts\fR |
1882 | .IX Subsection "Be smart about timeouts" |
1920 | .IX Subsection "Be smart about timeouts" |
1883 | .PP |
1921 | .PP |
1884 | 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 |
… | |
… | |
1966 | .Sp |
2004 | .Sp |
1967 | 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, |
1968 | 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 |
1969 | within the callback: |
2007 | within the callback: |
1970 | .Sp |
2008 | .Sp |
1971 | .Vb 1 |
2009 | .Vb 3 |
|
|
2010 | \& ev_tstamp timeout = 60.; |
1972 | \& ev_tstamp last_activity; // time of last activity |
2011 | \& ev_tstamp last_activity; // time of last activity |
|
|
2012 | \& ev_timer timer; |
1973 | \& |
2013 | \& |
1974 | \& static void |
2014 | \& static void |
1975 | \& callback (EV_P_ ev_timer *w, int revents) |
2015 | \& callback (EV_P_ ev_timer *w, int revents) |
1976 | \& { |
2016 | \& { |
1977 | \& ev_tstamp now = ev_now (EV_A); |
2017 | \& // calculate when the timeout would happen |
1978 | \& ev_tstamp timeout = last_activity + 60.; |
2018 | \& ev_tstamp after = last_activity \- ev_now (EV_A) + timeout; |
1979 | \& |
2019 | \& |
1980 | \& // if last_activity + 60. is older than now, we did time out |
2020 | \& // if negative, it means we the timeout already occurred |
1981 | \& if (timeout < now) |
2021 | \& if (after < 0.) |
1982 | \& { |
2022 | \& { |
1983 | \& // timeout occurred, take action |
2023 | \& // timeout occurred, take action |
1984 | \& } |
2024 | \& } |
1985 | \& else |
2025 | \& else |
1986 | \& { |
2026 | \& { |
1987 | \& // callback was invoked, but there was some activity, re\-arm |
2027 | \& // callback was invoked, but there was some recent |
1988 | \& // the watcher to fire in last_activity + 60, which is |
2028 | \& // activity. simply restart the timer to time out |
1989 | \& // guaranteed to be in the future, so "again" is positive: |
2029 | \& // after "after" seconds, which is the earliest time |
1990 | \& w\->repeat = timeout \- now; |
2030 | \& // the timeout can occur. |
|
|
2031 | \& ev_timer_set (w, after, 0.); |
1991 | \& ev_timer_again (EV_A_ w); |
2032 | \& ev_timer_start (EV_A_ w); |
1992 | \& } |
2033 | \& } |
1993 | \& } |
2034 | \& } |
1994 | .Ve |
2035 | .Ve |
1995 | .Sp |
2036 | .Sp |
1996 | To summarise the callback: first calculate the real timeout (defined |
2037 | To summarise the callback: first calculate in how many seconds the |
1997 | 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, |
1998 | 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 |
1999 | the callback was invoked too early (\f(CW\*(C`timeout\*(C'\fR is in the future), so |
2040 | (EV_A)\*(C'\fR from that). |
2000 | re-schedule the timer to fire at that future time, to see if maybe we have |
|
|
2001 | a timeout then. |
|
|
2002 | .Sp |
2041 | .Sp |
2003 | 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 |
2004 | \&\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. |
2005 | .Sp |
2051 | .Sp |
2006 | This scheme causes more callback invocations (about one every 60 seconds |
2052 | This scheme causes more callback invocations (about one every 60 seconds |
2007 | 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 |
2008 | libev to change the timeout. |
2054 | libev to change the timeout. |
2009 | .Sp |
2055 | .Sp |
2010 | 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 |
2011 | 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 |
2012 | 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: |
2013 | .Sp |
2060 | .Sp |
2014 | .Vb 3 |
2061 | .Vb 3 |
|
|
2062 | \& last_activity = ev_now (EV_A); |
2015 | \& ev_init (timer, callback); |
2063 | \& ev_init (&timer, callback); |
2016 | \& last_activity = ev_now (loop); |
2064 | \& callback (EV_A_ &timer, 0); |
2017 | \& callback (loop, timer, EV_TIMER); |
|
|
2018 | .Ve |
2065 | .Ve |
2019 | .Sp |
2066 | .Sp |
2020 | And when there is some activity, simply store the current time in |
2067 | When there is some activity, simply store the current time in |
2021 | \&\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: |
2022 | .Sp |
2069 | .Sp |
2023 | .Vb 1 |
2070 | .Vb 2 |
|
|
2071 | \& if (activity detected) |
2024 | \& 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); |
2025 | .Ve |
2083 | .Ve |
2026 | .Sp |
2084 | .Sp |
2027 | 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 |
2028 | time-out is unlikely to be triggered, much more efficient. |
2086 | time-out is unlikely to be triggered, much more efficient. |
2029 | .Sp |
|
|
2030 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
|
|
2031 | callback :) \- just change the timeout and invoke the callback, which will |
|
|
2032 | fix things for you. |
|
|
2033 | .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 |
2034 | .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." |
2035 | If there is not one request, but many thousands (millions...), all |
2089 | If there is not one request, but many thousands (millions...), all |
2036 | 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 |
2037 | do even better: |
2091 | do even better: |
… | |
… | |
2061 | 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 |
2062 | rather complicated, but extremely efficient, something that really pays |
2116 | rather complicated, but extremely efficient, something that really pays |
2063 | 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 |
2064 | overkill :) |
2118 | overkill :) |
2065 | .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 |
2066 | \fIThe special problem of time updates\fR |
2158 | \fIThe special problem of time updates\fR |
2067 | .IX Subsection "The special problem of time updates" |
2159 | .IX Subsection "The special problem of time updates" |
2068 | .PP |
2160 | .PP |
2069 | Establishing the current time is a costly operation (it usually takes at |
2161 | Establishing the current time is a costly operation (it usually takes |
2070 | 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 |
2071 | 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 |
2072 | 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 |
2073 | lots of events in one iteration. |
2165 | lots of events in one iteration. |
2074 | .PP |
2166 | .PP |
2075 | 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 |
2076 | 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 |
2077 | of the event triggering whatever timeout you are modifying/starting. If |
2169 | of the event triggering whatever timeout you are modifying/starting. If |
2078 | 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 |
2079 | 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: |
2080 | .PP |
2173 | .PP |
2081 | .Vb 1 |
2174 | .Vb 1 |
2082 | \& ev_timer_set (&timer, after + ev_now () \- ev_time (), 0.); |
2175 | \& ev_timer_set (&timer, after + (ev_time () \- ev_now ()), 0.); |
2083 | .Ve |
2176 | .Ve |
2084 | .PP |
2177 | .PP |
2085 | 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 |
2086 | 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 |
2087 | ()\*(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. |
2088 | .PP |
2216 | .PP |
2089 | \fIThe special problems of suspended animation\fR |
2217 | \fIThe special problems of suspended animation\fR |
2090 | .IX Subsection "The special problems of suspended animation" |
2218 | .IX Subsection "The special problems of suspended animation" |
2091 | .PP |
2219 | .PP |
2092 | 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 |
… | |
… | |
2123 | .IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" |
2251 | .IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" |
2124 | .PD 0 |
2252 | .PD 0 |
2125 | .IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4 |
2253 | .IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4 |
2126 | .IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" |
2254 | .IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" |
2127 | .PD |
2255 | .PD |
2128 | Configure the timer to trigger after \f(CW\*(C`after\*(C'\fR seconds. If \f(CW\*(C`repeat\*(C'\fR |
2256 | Configure the timer to trigger after \f(CW\*(C`after\*(C'\fR seconds (fractional and |
2129 | is \f(CW0.\fR, then it will automatically be stopped once the timeout is |
2257 | negative values are supported). If \f(CW\*(C`repeat\*(C'\fR is \f(CW0.\fR, then it will |
2130 | reached. If it is positive, then the timer will automatically be |
2258 | automatically be stopped once the timeout is reached. If it is positive, |
2131 | configured to trigger again \f(CW\*(C`repeat\*(C'\fR seconds later, again, and again, |
2259 | then the timer will automatically be configured to trigger again \f(CW\*(C`repeat\*(C'\fR |
2132 | until stopped manually. |
2260 | seconds later, again, and again, until stopped manually. |
2133 | .Sp |
2261 | .Sp |
2134 | The timer itself will do a best-effort at avoiding drift, that is, if |
2262 | The timer itself will do a best-effort at avoiding drift, that is, if |
2135 | you configure a timer to trigger every 10 seconds, then it will normally |
2263 | you configure a timer to trigger every 10 seconds, then it will normally |
2136 | trigger at exactly 10 second intervals. If, however, your program cannot |
2264 | trigger at exactly 10 second intervals. If, however, your program cannot |
2137 | 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 |
2138 | 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. |
2139 | .IP "ev_timer_again (loop, ev_timer *)" 4 |
2267 | .IP "ev_timer_again (loop, ev_timer *)" 4 |
2140 | .IX Item "ev_timer_again (loop, ev_timer *)" |
2268 | .IX Item "ev_timer_again (loop, ev_timer *)" |
2141 | 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 |
2142 | 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. |
2143 | .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 |
2144 | If the timer is pending, its pending status is cleared. |
2276 | .IP "If the timer is pending, the pending status is always cleared." 4 |
2145 | .Sp |
2277 | .IX Item "If the timer is pending, the pending status is always cleared." |
|
|
2278 | .PD 0 |
2146 | 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 |
2147 | .Sp |
2280 | .IX Item "If the timer is started but non-repeating, stop it (as if it timed out, without invoking it)." |
2148 | 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 |
2149 | \&\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 |
2150 | .Sp |
2287 | .Sp |
2151 | 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 |
2152 | usage example. |
2289 | usage example. |
|
|
2290 | .RE |
2153 | .IP "ev_tstamp ev_timer_remaining (loop, ev_timer *)" 4 |
2291 | .IP "ev_tstamp ev_timer_remaining (loop, ev_timer *)" 4 |
2154 | .IX Item "ev_tstamp ev_timer_remaining (loop, ev_timer *)" |
2292 | .IX Item "ev_tstamp ev_timer_remaining (loop, ev_timer *)" |
2155 | 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, |
2156 | 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 |
2157 | the timeout value currently configured. |
2295 | the timeout value currently configured. |
… | |
… | |
2209 | 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 |
2210 | (and unfortunately a bit complex). |
2348 | (and unfortunately a bit complex). |
2211 | .PP |
2349 | .PP |
2212 | 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 |
2213 | 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 |
2214 | (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 |
2215 | 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 |
2216 | 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 |
2217 | wrist-watch). |
2355 | wrist-watch). |
2218 | .PP |
2356 | .PP |
2219 | 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 |
… | |
… | |
2224 | \&\f(CW\*(C`ev_timer\*(C'\fR, which would still trigger roughly 10 seconds after starting |
2362 | \&\f(CW\*(C`ev_timer\*(C'\fR, which would still trigger roughly 10 seconds after starting |
2225 | it, as it uses a relative timeout). |
2363 | it, as it uses a relative timeout). |
2226 | .PP |
2364 | .PP |
2227 | \&\f(CW\*(C`ev_periodic\*(C'\fR watchers can also be used to implement vastly more complex |
2365 | \&\f(CW\*(C`ev_periodic\*(C'\fR watchers can also be used to implement vastly more complex |
2228 | timers, such as triggering an event on each \*(L"midnight, local time\*(R", or |
2366 | timers, such as triggering an event on each \*(L"midnight, local time\*(R", or |
2229 | other complicated rules. This cannot be done with \f(CW\*(C`ev_timer\*(C'\fR watchers, as |
2367 | other complicated rules. This cannot easily be done with \f(CW\*(C`ev_timer\*(C'\fR |
2230 | those cannot react to time jumps. |
2368 | watchers, as those cannot react to time jumps. |
2231 | .PP |
2369 | .PP |
2232 | As with timers, the callback is guaranteed to be invoked only when the |
2370 | As with timers, the callback is guaranteed to be invoked only when the |
2233 | point in time where it is supposed to trigger has passed. If multiple |
2371 | point in time where it is supposed to trigger has passed. If multiple |
2234 | timers become ready during the same loop iteration then the ones with |
2372 | timers become ready during the same loop iteration then the ones with |
2235 | earlier time-out values are invoked before ones with later time-out values |
2373 | earlier time-out values are invoked before ones with later time-out values |
… | |
… | |
2277 | .Sp |
2415 | .Sp |
2278 | 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 |
2279 | \&\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 |
2280 | 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. |
2281 | .Sp |
2419 | .Sp |
2282 | 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 |
2283 | \&\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 |
2284 | 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. |
2285 | .Sp |
2426 | .Sp |
2286 | 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 |
2287 | 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 |
2288 | 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 |
2289 | 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). |
… | |
… | |
2293 | 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 |
2294 | ignored. Instead, each time the periodic watcher gets scheduled, the |
2435 | ignored. Instead, each time the periodic watcher gets scheduled, the |
2295 | 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 |
2296 | current time as second argument. |
2437 | current time as second argument. |
2297 | .Sp |
2438 | .Sp |
2298 | \&\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, |
2299 | 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 |
2300 | allowed by documentation here\fR. |
2441 | allowed by documentation here\fR. |
2301 | .Sp |
2442 | .Sp |
2302 | 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 |
2303 | 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 |
… | |
… | |
2317 | 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 |
2318 | (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 |
2319 | 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 |
2320 | might be called at other times, too. |
2461 | might be called at other times, too. |
2321 | .Sp |
2462 | .Sp |
2322 | \&\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 |
2323 | 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. |
2324 | .Sp |
2465 | .Sp |
2325 | 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 |
2326 | 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 |
2327 | next midnight after \f(CW\*(C`now\*(C'\fR and return the timestamp value for this. How |
2468 | the next midnight after \f(CW\*(C`now\*(C'\fR and return the timestamp value for |
2328 | you do this is, again, up to you (but it is not trivial, which is the main |
2469 | this. Here is a (completely untested, no error checking) example on how to |
2329 | reason I omitted it as an example). |
2470 | do this: |
|
|
2471 | .Sp |
|
|
2472 | .Vb 1 |
|
|
2473 | \& #include <time.h> |
|
|
2474 | \& |
|
|
2475 | \& static ev_tstamp |
|
|
2476 | \& my_rescheduler (ev_periodic *w, ev_tstamp now) |
|
|
2477 | \& { |
|
|
2478 | \& time_t tnow = (time_t)now; |
|
|
2479 | \& struct tm tm; |
|
|
2480 | \& localtime_r (&tnow, &tm); |
|
|
2481 | \& |
|
|
2482 | \& tm.tm_sec = tm.tm_min = tm.tm_hour = 0; // midnight current day |
|
|
2483 | \& ++tm.tm_mday; // midnight next day |
|
|
2484 | \& |
|
|
2485 | \& return mktime (&tm); |
|
|
2486 | \& } |
|
|
2487 | .Ve |
|
|
2488 | .Sp |
|
|
2489 | Note: this code might run into trouble on days that have more then two |
|
|
2490 | midnights (beginning and end). |
2330 | .RE |
2491 | .RE |
2331 | .RS 4 |
2492 | .RS 4 |
2332 | .RE |
2493 | .RE |
2333 | .IP "ev_periodic_again (loop, ev_periodic *)" 4 |
2494 | .IP "ev_periodic_again (loop, ev_periodic *)" 4 |
2334 | .IX Item "ev_periodic_again (loop, ev_periodic *)" |
2495 | .IX Item "ev_periodic_again (loop, ev_periodic *)" |
… | |
… | |
2419 | only within the same loop, i.e. you can watch for \f(CW\*(C`SIGINT\*(C'\fR in your |
2580 | only within the same loop, i.e. you can watch for \f(CW\*(C`SIGINT\*(C'\fR in your |
2420 | default loop and for \f(CW\*(C`SIGIO\*(C'\fR in another loop, but you cannot watch for |
2581 | default loop and for \f(CW\*(C`SIGIO\*(C'\fR in another loop, but you cannot watch for |
2421 | \&\f(CW\*(C`SIGINT\*(C'\fR in both the default loop and another loop at the same time. At |
2582 | \&\f(CW\*(C`SIGINT\*(C'\fR in both the default loop and another loop at the same time. At |
2422 | the moment, \f(CW\*(C`SIGCHLD\*(C'\fR is permanently tied to the default loop. |
2583 | the moment, \f(CW\*(C`SIGCHLD\*(C'\fR is permanently tied to the default loop. |
2423 | .PP |
2584 | .PP |
2424 | When the first watcher gets started will libev actually register something |
2585 | Only after the first watcher for a signal is started will libev actually |
2425 | with the kernel (thus it coexists with your own signal handlers as long as |
2586 | register something with the kernel. It thus coexists with your own signal |
2426 | you don't register any with libev for the same signal). |
2587 | handlers as long as you don't register any with libev for the same signal. |
2427 | .PP |
2588 | .PP |
2428 | If possible and supported, libev will install its handlers with |
2589 | If possible and supported, libev will install its handlers with |
2429 | \&\f(CW\*(C`SA_RESTART\*(C'\fR (or equivalent) behaviour enabled, so system calls should |
2590 | \&\f(CW\*(C`SA_RESTART\*(C'\fR (or equivalent) behaviour enabled, so system calls should |
2430 | not be unduly interrupted. If you have a problem with system calls getting |
2591 | not be unduly interrupted. If you have a problem with system calls getting |
2431 | interrupted by signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher |
2592 | interrupted by signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher |
… | |
… | |
2452 | The simplest way to ensure that the signal mask is reset in the child is |
2613 | The simplest way to ensure that the signal mask is reset in the child is |
2453 | to install a fork handler with \f(CW\*(C`pthread_atfork\*(C'\fR that resets it. That will |
2614 | to install a fork handler with \f(CW\*(C`pthread_atfork\*(C'\fR that resets it. That will |
2454 | catch fork calls done by libraries (such as the libc) as well. |
2615 | catch fork calls done by libraries (such as the libc) as well. |
2455 | .PP |
2616 | .PP |
2456 | In current versions of libev, the signal will not be blocked indefinitely |
2617 | In current versions of libev, the signal will not be blocked indefinitely |
2457 | unless you use the \f(CW\*(C`signalfd\*(C'\fR \s-1API\s0 (\f(CW\*(C`EV_SIGNALFD\*(C'\fR). While this reduces |
2618 | unless you use the \f(CW\*(C`signalfd\*(C'\fR \s-1API \s0(\f(CW\*(C`EV_SIGNALFD\*(C'\fR). While this reduces |
2458 | the window of opportunity for problems, it will not go away, as libev |
2619 | the window of opportunity for problems, it will not go away, as libev |
2459 | \&\fIhas\fR to modify the signal mask, at least temporarily. |
2620 | \&\fIhas\fR to modify the signal mask, at least temporarily. |
2460 | .PP |
2621 | .PP |
2461 | So I can't stress this enough: \fIIf you do not reset your signal mask when |
2622 | So I can't stress this enough: \fIIf you do not reset your signal mask when |
2462 | you expect it to be empty, you have a race condition in your code\fR. This |
2623 | you expect it to be empty, you have a race condition in your code\fR. This |
… | |
… | |
2492 | The signal the watcher watches out for. |
2653 | The signal the watcher watches out for. |
2493 | .PP |
2654 | .PP |
2494 | \fIExamples\fR |
2655 | \fIExamples\fR |
2495 | .IX Subsection "Examples" |
2656 | .IX Subsection "Examples" |
2496 | .PP |
2657 | .PP |
2497 | Example: Try to exit cleanly on \s-1SIGINT\s0. |
2658 | Example: Try to exit cleanly on \s-1SIGINT.\s0 |
2498 | .PP |
2659 | .PP |
2499 | .Vb 5 |
2660 | .Vb 5 |
2500 | \& static void |
2661 | \& static void |
2501 | \& sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2662 | \& sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2502 | \& { |
2663 | \& { |
… | |
… | |
2617 | .ie n .SS """ev_stat"" \- did the file attributes just change?" |
2778 | .ie n .SS """ev_stat"" \- did the file attributes just change?" |
2618 | .el .SS "\f(CWev_stat\fP \- did the file attributes just change?" |
2779 | .el .SS "\f(CWev_stat\fP \- did the file attributes just change?" |
2619 | .IX Subsection "ev_stat - did the file attributes just change?" |
2780 | .IX Subsection "ev_stat - did the file attributes just change?" |
2620 | This watches a file system path for attribute changes. That is, it calls |
2781 | This watches a file system path for attribute changes. That is, it calls |
2621 | \&\f(CW\*(C`stat\*(C'\fR on that path in regular intervals (or when the \s-1OS\s0 says it changed) |
2782 | \&\f(CW\*(C`stat\*(C'\fR on that path in regular intervals (or when the \s-1OS\s0 says it changed) |
2622 | and sees if it changed compared to the last time, invoking the callback if |
2783 | and sees if it changed compared to the last time, invoking the callback |
2623 | it did. |
2784 | if it did. Starting the watcher \f(CW\*(C`stat\*(C'\fR's the file, so only changes that |
|
|
2785 | happen after the watcher has been started will be reported. |
2624 | .PP |
2786 | .PP |
2625 | The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does |
2787 | The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does |
2626 | not exist\*(R" is a status change like any other. The condition \*(L"path does not |
2788 | not exist\*(R" is a status change like any other. The condition \*(L"path does not |
2627 | exist\*(R" (or more correctly \*(L"path cannot be stat'ed\*(R") is signified by the |
2789 | exist\*(R" (or more correctly \*(L"path cannot be stat'ed\*(R") is signified by the |
2628 | \&\f(CW\*(C`st_nlink\*(C'\fR field being zero (which is otherwise always forced to be at |
2790 | \&\f(CW\*(C`st_nlink\*(C'\fR field being zero (which is otherwise always forced to be at |
… | |
… | |
2658 | compilation environment, which means that on systems with large file |
2820 | compilation environment, which means that on systems with large file |
2659 | support disabled by default, you get the 32 bit version of the stat |
2821 | support disabled by default, you get the 32 bit version of the stat |
2660 | structure. When using the library from programs that change the \s-1ABI\s0 to |
2822 | structure. When using the library from programs that change the \s-1ABI\s0 to |
2661 | use 64 bit file offsets the programs will fail. In that case you have to |
2823 | use 64 bit file offsets the programs will fail. In that case you have to |
2662 | compile libev with the same flags to get binary compatibility. This is |
2824 | compile libev with the same flags to get binary compatibility. This is |
2663 | obviously the case with any flags that change the \s-1ABI\s0, but the problem is |
2825 | obviously the case with any flags that change the \s-1ABI,\s0 but the problem is |
2664 | most noticeably displayed with ev_stat and large file support. |
2826 | most noticeably displayed with ev_stat and large file support. |
2665 | .PP |
2827 | .PP |
2666 | The solution for this is to lobby your distribution maker to make large |
2828 | The solution for this is to lobby your distribution maker to make large |
2667 | file interfaces available by default (as e.g. FreeBSD does) and not |
2829 | file interfaces available by default (as e.g. FreeBSD does) and not |
2668 | optional. Libev cannot simply switch on large file support because it has |
2830 | optional. Libev cannot simply switch on large file support because it has |
… | |
… | |
2859 | Apart from keeping your process non-blocking (which is a useful |
3021 | Apart from keeping your process non-blocking (which is a useful |
2860 | effect on its own sometimes), idle watchers are a good place to do |
3022 | effect on its own sometimes), idle watchers are a good place to do |
2861 | \&\*(L"pseudo-background processing\*(R", or delay processing stuff to after the |
3023 | \&\*(L"pseudo-background processing\*(R", or delay processing stuff to after the |
2862 | event loop has handled all outstanding events. |
3024 | event loop has handled all outstanding events. |
2863 | .PP |
3025 | .PP |
|
|
3026 | \fIAbusing an \f(CI\*(C`ev_idle\*(C'\fI watcher for its side-effect\fR |
|
|
3027 | .IX Subsection "Abusing an ev_idle watcher for its side-effect" |
|
|
3028 | .PP |
|
|
3029 | As long as there is at least one active idle watcher, libev will never |
|
|
3030 | sleep unnecessarily. Or in other words, it will loop as fast as possible. |
|
|
3031 | For this to work, the idle watcher doesn't need to be invoked at all \- the |
|
|
3032 | lowest priority will do. |
|
|
3033 | .PP |
|
|
3034 | This mode of operation can be useful together with an \f(CW\*(C`ev_check\*(C'\fR watcher, |
|
|
3035 | to do something on each event loop iteration \- for example to balance load |
|
|
3036 | between different connections. |
|
|
3037 | .PP |
|
|
3038 | See \*(L"Abusing an ev_check watcher for its side-effect\*(R" for a longer |
|
|
3039 | example. |
|
|
3040 | .PP |
2864 | \fIWatcher-Specific Functions and Data Members\fR |
3041 | \fIWatcher-Specific Functions and Data Members\fR |
2865 | .IX Subsection "Watcher-Specific Functions and Data Members" |
3042 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2866 | .IP "ev_idle_init (ev_idle *, callback)" 4 |
3043 | .IP "ev_idle_init (ev_idle *, callback)" 4 |
2867 | .IX Item "ev_idle_init (ev_idle *, callback)" |
3044 | .IX Item "ev_idle_init (ev_idle *, callback)" |
2868 | Initialises and configures the idle watcher \- it has no parameters of any |
3045 | Initialises and configures the idle watcher \- it has no parameters of any |
… | |
… | |
2873 | .IX Subsection "Examples" |
3050 | .IX Subsection "Examples" |
2874 | .PP |
3051 | .PP |
2875 | Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the |
3052 | Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the |
2876 | callback, free it. Also, use no error checking, as usual. |
3053 | callback, free it. Also, use no error checking, as usual. |
2877 | .PP |
3054 | .PP |
2878 | .Vb 7 |
3055 | .Vb 5 |
2879 | \& static void |
3056 | \& static void |
2880 | \& idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
3057 | \& idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
2881 | \& { |
3058 | \& { |
|
|
3059 | \& // stop the watcher |
|
|
3060 | \& ev_idle_stop (loop, w); |
|
|
3061 | \& |
|
|
3062 | \& // now we can free it |
2882 | \& free (w); |
3063 | \& free (w); |
|
|
3064 | \& |
2883 | \& // now do something you wanted to do when the program has |
3065 | \& // now do something you wanted to do when the program has |
2884 | \& // no longer anything immediate to do. |
3066 | \& // no longer anything immediate to do. |
2885 | \& } |
3067 | \& } |
2886 | \& |
3068 | \& |
2887 | \& ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
3069 | \& ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
… | |
… | |
2889 | \& ev_idle_start (loop, idle_watcher); |
3071 | \& ev_idle_start (loop, idle_watcher); |
2890 | .Ve |
3072 | .Ve |
2891 | .ie n .SS """ev_prepare"" and ""ev_check"" \- customise your event loop!" |
3073 | .ie n .SS """ev_prepare"" and ""ev_check"" \- customise your event loop!" |
2892 | .el .SS "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!" |
3074 | .el .SS "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!" |
2893 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
3075 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
2894 | Prepare and check watchers are usually (but not always) used in pairs: |
3076 | Prepare and check watchers are often (but not always) used in pairs: |
2895 | prepare watchers get invoked before the process blocks and check watchers |
3077 | prepare watchers get invoked before the process blocks and check watchers |
2896 | afterwards. |
3078 | afterwards. |
2897 | .PP |
3079 | .PP |
2898 | You \fImust not\fR call \f(CW\*(C`ev_run\*(C'\fR or similar functions that enter |
3080 | You \fImust not\fR call \f(CW\*(C`ev_run\*(C'\fR (or similar functions that enter the |
2899 | the current event loop from either \f(CW\*(C`ev_prepare\*(C'\fR or \f(CW\*(C`ev_check\*(C'\fR |
3081 | current event loop) or \f(CW\*(C`ev_loop_fork\*(C'\fR from either \f(CW\*(C`ev_prepare\*(C'\fR or |
2900 | watchers. Other loops than the current one are fine, however. The |
3082 | \&\f(CW\*(C`ev_check\*(C'\fR watchers. Other loops than the current one are fine, |
2901 | rationale behind this is that you do not need to check for recursion in |
3083 | however. The rationale behind this is that you do not need to check |
2902 | those watchers, i.e. the sequence will always be \f(CW\*(C`ev_prepare\*(C'\fR, blocking, |
3084 | for recursion in those watchers, i.e. the sequence will always be |
2903 | \&\f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each kind they will always be |
3085 | \&\f(CW\*(C`ev_prepare\*(C'\fR, blocking, \f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each |
2904 | called in pairs bracketing the blocking call. |
3086 | kind they will always be called in pairs bracketing the blocking call. |
2905 | .PP |
3087 | .PP |
2906 | Their main purpose is to integrate other event mechanisms into libev and |
3088 | Their main purpose is to integrate other event mechanisms into libev and |
2907 | their use is somewhat advanced. They could be used, for example, to track |
3089 | their use is somewhat advanced. They could be used, for example, to track |
2908 | variable changes, implement your own watchers, integrate net-snmp or a |
3090 | variable changes, implement your own watchers, integrate net-snmp or a |
2909 | coroutine library and lots more. They are also occasionally useful if |
3091 | coroutine library and lots more. They are also occasionally useful if |
… | |
… | |
2927 | with priority higher than or equal to the event loop and one coroutine |
3109 | with priority higher than or equal to the event loop and one coroutine |
2928 | of lower priority, but only once, using idle watchers to keep the event |
3110 | of lower priority, but only once, using idle watchers to keep the event |
2929 | loop from blocking if lower-priority coroutines are active, thus mapping |
3111 | loop from blocking if lower-priority coroutines are active, thus mapping |
2930 | low-priority coroutines to idle/background tasks). |
3112 | low-priority coroutines to idle/background tasks). |
2931 | .PP |
3113 | .PP |
2932 | It is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR) |
3114 | When used for this purpose, it is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers |
2933 | priority, to ensure that they are being run before any other watchers |
3115 | highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR) priority, to ensure that they are being run before |
2934 | after the poll (this doesn't matter for \f(CW\*(C`ev_prepare\*(C'\fR watchers). |
3116 | any other watchers after the poll (this doesn't matter for \f(CW\*(C`ev_prepare\*(C'\fR |
|
|
3117 | watchers). |
2935 | .PP |
3118 | .PP |
2936 | Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers, too) should not |
3119 | Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers, too) should not |
2937 | activate (\*(L"feed\*(R") events into libev. While libev fully supports this, they |
3120 | activate (\*(L"feed\*(R") events into libev. While libev fully supports this, they |
2938 | might get executed before other \f(CW\*(C`ev_check\*(C'\fR watchers did their job. As |
3121 | might get executed before other \f(CW\*(C`ev_check\*(C'\fR watchers did their job. As |
2939 | \&\f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other (non-libev) event |
3122 | \&\f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other (non-libev) event |
2940 | loops those other event loops might be in an unusable state until their |
3123 | loops those other event loops might be in an unusable state until their |
2941 | \&\f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to coexist peacefully with |
3124 | \&\f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to coexist peacefully with |
2942 | others). |
3125 | others). |
|
|
3126 | .PP |
|
|
3127 | \fIAbusing an \f(CI\*(C`ev_check\*(C'\fI watcher for its side-effect\fR |
|
|
3128 | .IX Subsection "Abusing an ev_check watcher for its side-effect" |
|
|
3129 | .PP |
|
|
3130 | \&\f(CW\*(C`ev_check\*(C'\fR (and less often also \f(CW\*(C`ev_prepare\*(C'\fR) watchers can also be |
|
|
3131 | useful because they are called once per event loop iteration. For |
|
|
3132 | example, if you want to handle a large number of connections fairly, you |
|
|
3133 | normally only do a bit of work for each active connection, and if there |
|
|
3134 | is more work to do, you wait for the next event loop iteration, so other |
|
|
3135 | connections have a chance of making progress. |
|
|
3136 | .PP |
|
|
3137 | Using an \f(CW\*(C`ev_check\*(C'\fR watcher is almost enough: it will be called on the |
|
|
3138 | next event loop iteration. However, that isn't as soon as possible \- |
|
|
3139 | without external events, your \f(CW\*(C`ev_check\*(C'\fR watcher will not be invoked. |
|
|
3140 | .PP |
|
|
3141 | This is where \f(CW\*(C`ev_idle\*(C'\fR watchers come in handy \- all you need is a |
|
|
3142 | single global idle watcher that is active as long as you have one active |
|
|
3143 | \&\f(CW\*(C`ev_check\*(C'\fR watcher. The \f(CW\*(C`ev_idle\*(C'\fR watcher makes sure the event loop |
|
|
3144 | will not sleep, and the \f(CW\*(C`ev_check\*(C'\fR watcher makes sure a callback gets |
|
|
3145 | invoked. Neither watcher alone can do that. |
2943 | .PP |
3146 | .PP |
2944 | \fIWatcher-Specific Functions and Data Members\fR |
3147 | \fIWatcher-Specific Functions and Data Members\fR |
2945 | .IX Subsection "Watcher-Specific Functions and Data Members" |
3148 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2946 | .IP "ev_prepare_init (ev_prepare *, callback)" 4 |
3149 | .IP "ev_prepare_init (ev_prepare *, callback)" 4 |
2947 | .IX Item "ev_prepare_init (ev_prepare *, callback)" |
3150 | .IX Item "ev_prepare_init (ev_prepare *, callback)" |
… | |
… | |
3058 | .Ve |
3261 | .Ve |
3059 | .PP |
3262 | .PP |
3060 | Method 4: Do not use a prepare or check watcher because the module you |
3263 | Method 4: Do not use a prepare or check watcher because the module you |
3061 | want to embed is not flexible enough to support it. Instead, you can |
3264 | want to embed is not flexible enough to support it. Instead, you can |
3062 | override their poll function. The drawback with this solution is that the |
3265 | override their poll function. The drawback with this solution is that the |
3063 | main loop is now no longer controllable by \s-1EV\s0. The \f(CW\*(C`Glib::EV\*(C'\fR module uses |
3266 | main loop is now no longer controllable by \s-1EV.\s0 The \f(CW\*(C`Glib::EV\*(C'\fR module uses |
3064 | this approach, effectively embedding \s-1EV\s0 as a client into the horrible |
3267 | this approach, effectively embedding \s-1EV\s0 as a client into the horrible |
3065 | libglib event loop. |
3268 | libglib event loop. |
3066 | .PP |
3269 | .PP |
3067 | .Vb 4 |
3270 | .Vb 4 |
3068 | \& static gint |
3271 | \& static gint |
… | |
… | |
3152 | \fIWatcher-Specific Functions and Data Members\fR |
3355 | \fIWatcher-Specific Functions and Data Members\fR |
3153 | .IX Subsection "Watcher-Specific Functions and Data Members" |
3356 | .IX Subsection "Watcher-Specific Functions and Data Members" |
3154 | .IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
3357 | .IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
3155 | .IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" |
3358 | .IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" |
3156 | .PD 0 |
3359 | .PD 0 |
3157 | .IP "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
3360 | .IP "ev_embed_set (ev_embed *, struct ev_loop *embedded_loop)" 4 |
3158 | .IX Item "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" |
3361 | .IX Item "ev_embed_set (ev_embed *, struct ev_loop *embedded_loop)" |
3159 | .PD |
3362 | .PD |
3160 | Configures the watcher to embed the given loop, which must be |
3363 | Configures the watcher to embed the given loop, which must be |
3161 | embeddable. If the callback is \f(CW0\fR, then \f(CW\*(C`ev_embed_sweep\*(C'\fR will be |
3364 | embeddable. If the callback is \f(CW0\fR, then \f(CW\*(C`ev_embed_sweep\*(C'\fR will be |
3162 | invoked automatically, otherwise it is the responsibility of the callback |
3365 | invoked automatically, otherwise it is the responsibility of the callback |
3163 | to invoke it (it will continue to be called until the sweep has been done, |
3366 | to invoke it (it will continue to be called until the sweep has been done, |
… | |
… | |
3182 | .PP |
3385 | .PP |
3183 | .Vb 3 |
3386 | .Vb 3 |
3184 | \& struct ev_loop *loop_hi = ev_default_init (0); |
3387 | \& struct ev_loop *loop_hi = ev_default_init (0); |
3185 | \& struct ev_loop *loop_lo = 0; |
3388 | \& struct ev_loop *loop_lo = 0; |
3186 | \& ev_embed embed; |
3389 | \& ev_embed embed; |
3187 | \& |
3390 | \& |
3188 | \& // see if there is a chance of getting one that works |
3391 | \& // see if there is a chance of getting one that works |
3189 | \& // (remember that a flags value of 0 means autodetection) |
3392 | \& // (remember that a flags value of 0 means autodetection) |
3190 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3393 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3191 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3394 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3192 | \& : 0; |
3395 | \& : 0; |
… | |
… | |
3208 | .PP |
3411 | .PP |
3209 | .Vb 3 |
3412 | .Vb 3 |
3210 | \& struct ev_loop *loop = ev_default_init (0); |
3413 | \& struct ev_loop *loop = ev_default_init (0); |
3211 | \& struct ev_loop *loop_socket = 0; |
3414 | \& struct ev_loop *loop_socket = 0; |
3212 | \& ev_embed embed; |
3415 | \& ev_embed embed; |
3213 | \& |
3416 | \& |
3214 | \& if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3417 | \& if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3215 | \& if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3418 | \& if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3216 | \& { |
3419 | \& { |
3217 | \& ev_embed_init (&embed, 0, loop_socket); |
3420 | \& ev_embed_init (&embed, 0, loop_socket); |
3218 | \& ev_embed_start (loop, &embed); |
3421 | \& ev_embed_start (loop, &embed); |
… | |
… | |
3226 | .ie n .SS """ev_fork"" \- the audacity to resume the event loop after a fork" |
3429 | .ie n .SS """ev_fork"" \- the audacity to resume the event loop after a fork" |
3227 | .el .SS "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
3430 | .el .SS "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
3228 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
3431 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
3229 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
3432 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
3230 | whoever is a good citizen cared to tell libev about it by calling |
3433 | whoever is a good citizen cared to tell libev about it by calling |
3231 | \&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the |
3434 | \&\f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the event loop blocks next |
3232 | event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, |
3435 | and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, and only in the child |
3233 | and only in the child after the fork. If whoever good citizen calling |
3436 | after the fork. If whoever good citizen calling \f(CW\*(C`ev_default_fork\*(C'\fR cheats |
3234 | \&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork |
3437 | and calls it in the wrong process, the fork handlers will be invoked, too, |
3235 | handlers will be invoked, too, of course. |
3438 | of course. |
3236 | .PP |
3439 | .PP |
3237 | \fIThe special problem of life after fork \- how is it possible?\fR |
3440 | \fIThe special problem of life after fork \- how is it possible?\fR |
3238 | .IX Subsection "The special problem of life after fork - how is it possible?" |
3441 | .IX Subsection "The special problem of life after fork - how is it possible?" |
3239 | .PP |
3442 | .PP |
3240 | Most uses of \f(CW\*(C`fork()\*(C'\fR consist of forking, then some simple calls to set |
3443 | Most uses of \f(CW\*(C`fork ()\*(C'\fR consist of forking, then some simple calls to set |
3241 | up/change the process environment, followed by a call to \f(CW\*(C`exec()\*(C'\fR. This |
3444 | up/change the process environment, followed by a call to \f(CW\*(C`exec()\*(C'\fR. This |
3242 | sequence should be handled by libev without any problems. |
3445 | sequence should be handled by libev without any problems. |
3243 | .PP |
3446 | .PP |
3244 | This changes when the application actually wants to do event handling |
3447 | This changes when the application actually wants to do event handling |
3245 | in the child, or both parent in child, in effect \*(L"continuing\*(R" after the |
3448 | in the child, or both parent in child, in effect \*(L"continuing\*(R" after the |
… | |
… | |
3326 | it by calling \f(CW\*(C`ev_async_send\*(C'\fR, which is thread\- and signal safe. |
3529 | it by calling \f(CW\*(C`ev_async_send\*(C'\fR, which is thread\- and signal safe. |
3327 | .PP |
3530 | .PP |
3328 | This functionality is very similar to \f(CW\*(C`ev_signal\*(C'\fR watchers, as signals, |
3531 | This functionality is very similar to \f(CW\*(C`ev_signal\*(C'\fR watchers, as signals, |
3329 | too, are asynchronous in nature, and signals, too, will be compressed |
3532 | too, are asynchronous in nature, and signals, too, will be compressed |
3330 | (i.e. the number of callback invocations may be less than the number of |
3533 | (i.e. the number of callback invocations may be less than the number of |
3331 | \&\f(CW\*(C`ev_async_sent\*(C'\fR calls). In fact, you could use signal watchers as a kind |
3534 | \&\f(CW\*(C`ev_async_send\*(C'\fR calls). In fact, you could use signal watchers as a kind |
3332 | of \*(L"global async watchers\*(R" by using a watcher on an otherwise unused |
3535 | of \*(L"global async watchers\*(R" by using a watcher on an otherwise unused |
3333 | signal, and \f(CW\*(C`ev_feed_signal\*(C'\fR to signal this watcher from another thread, |
3536 | signal, and \f(CW\*(C`ev_feed_signal\*(C'\fR to signal this watcher from another thread, |
3334 | even without knowing which loop owns the signal. |
3537 | even without knowing which loop owns the signal. |
3335 | .PP |
|
|
3336 | Unlike \f(CW\*(C`ev_signal\*(C'\fR watchers, \f(CW\*(C`ev_async\*(C'\fR works with any event loop, not |
|
|
3337 | just the default loop. |
|
|
3338 | .PP |
3538 | .PP |
3339 | \fIQueueing\fR |
3539 | \fIQueueing\fR |
3340 | .IX Subsection "Queueing" |
3540 | .IX Subsection "Queueing" |
3341 | .PP |
3541 | .PP |
3342 | \&\f(CW\*(C`ev_async\*(C'\fR does not support queueing of data in any way. The reason |
3542 | \&\f(CW\*(C`ev_async\*(C'\fR does not support queueing of data in any way. The reason |
… | |
… | |
3437 | Unlike \f(CW\*(C`ev_feed_event\*(C'\fR, this call is safe to do from other threads, |
3637 | Unlike \f(CW\*(C`ev_feed_event\*(C'\fR, this call is safe to do from other threads, |
3438 | signal or similar contexts (see the discussion of \f(CW\*(C`EV_ATOMIC_T\*(C'\fR in the |
3638 | signal or similar contexts (see the discussion of \f(CW\*(C`EV_ATOMIC_T\*(C'\fR in the |
3439 | embedding section below on what exactly this means). |
3639 | embedding section below on what exactly this means). |
3440 | .Sp |
3640 | .Sp |
3441 | Note that, as with other watchers in libev, multiple events might get |
3641 | Note that, as with other watchers in libev, multiple events might get |
3442 | compressed into a single callback invocation (another way to look at this |
3642 | compressed into a single callback invocation (another way to look at |
3443 | is that \f(CW\*(C`ev_async\*(C'\fR watchers are level-triggered, set on \f(CW\*(C`ev_async_send\*(C'\fR, |
3643 | this is that \f(CW\*(C`ev_async\*(C'\fR watchers are level-triggered: they are set on |
3444 | reset when the event loop detects that). |
3644 | \&\f(CW\*(C`ev_async_send\*(C'\fR, reset when the event loop detects that). |
3445 | .Sp |
3645 | .Sp |
3446 | This call incurs the overhead of a system call only once per event loop |
3646 | This call incurs the overhead of at most one extra system call per event |
3447 | iteration, so while the overhead might be noticeable, it doesn't apply to |
3647 | loop iteration, if the event loop is blocked, and no syscall at all if |
3448 | repeated calls to \f(CW\*(C`ev_async_send\*(C'\fR for the same event loop. |
3648 | the event loop (or your program) is processing events. That means that |
|
|
3649 | repeated calls are basically free (there is no need to avoid calls for |
|
|
3650 | performance reasons) and that the overhead becomes smaller (typically |
|
|
3651 | zero) under load. |
3449 | .IP "bool = ev_async_pending (ev_async *)" 4 |
3652 | .IP "bool = ev_async_pending (ev_async *)" 4 |
3450 | .IX Item "bool = ev_async_pending (ev_async *)" |
3653 | .IX Item "bool = ev_async_pending (ev_async *)" |
3451 | Returns a non-zero value when \f(CW\*(C`ev_async_send\*(C'\fR has been called on the |
3654 | Returns a non-zero value when \f(CW\*(C`ev_async_send\*(C'\fR has been called on the |
3452 | watcher but the event has not yet been processed (or even noted) by the |
3655 | watcher but the event has not yet been processed (or even noted) by the |
3453 | event loop. |
3656 | event loop. |
… | |
… | |
3462 | is a time window between the event loop checking and resetting the async |
3665 | is a time window between the event loop checking and resetting the async |
3463 | notification, and the callback being invoked. |
3666 | notification, and the callback being invoked. |
3464 | .SH "OTHER FUNCTIONS" |
3667 | .SH "OTHER FUNCTIONS" |
3465 | .IX Header "OTHER FUNCTIONS" |
3668 | .IX Header "OTHER FUNCTIONS" |
3466 | There are some other functions of possible interest. Described. Here. Now. |
3669 | There are some other functions of possible interest. Described. Here. Now. |
3467 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 |
3670 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback, arg)" 4 |
3468 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" |
3671 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback, arg)" |
3469 | This function combines a simple timer and an I/O watcher, calls your |
3672 | This function combines a simple timer and an I/O watcher, calls your |
3470 | callback on whichever event happens first and automatically stops both |
3673 | callback on whichever event happens first and automatically stops both |
3471 | watchers. This is useful if you want to wait for a single event on an fd |
3674 | watchers. This is useful if you want to wait for a single event on an fd |
3472 | or timeout without having to allocate/configure/start/stop/free one or |
3675 | or timeout without having to allocate/configure/start/stop/free one or |
3473 | more watchers yourself. |
3676 | more watchers yourself. |
… | |
… | |
3485 | \&\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 |
3688 | \&\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 |
3486 | value passed to \f(CW\*(C`ev_once\*(C'\fR. Note that it is possible to receive \fIboth\fR |
3689 | value passed to \f(CW\*(C`ev_once\*(C'\fR. Note that it is possible to receive \fIboth\fR |
3487 | a timeout and an io event at the same time \- you probably should give io |
3690 | a timeout and an io event at the same time \- you probably should give io |
3488 | events precedence. |
3691 | events precedence. |
3489 | .Sp |
3692 | .Sp |
3490 | Example: wait up to ten seconds for data to appear on \s-1STDIN_FILENO\s0. |
3693 | Example: wait up to ten seconds for data to appear on \s-1STDIN_FILENO.\s0 |
3491 | .Sp |
3694 | .Sp |
3492 | .Vb 7 |
3695 | .Vb 7 |
3493 | \& static void stdin_ready (int revents, void *arg) |
3696 | \& static void stdin_ready (int revents, void *arg) |
3494 | \& { |
3697 | \& { |
3495 | \& if (revents & EV_READ) |
3698 | \& if (revents & EV_READ) |
… | |
… | |
3501 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3704 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3502 | .Ve |
3705 | .Ve |
3503 | .IP "ev_feed_fd_event (loop, int fd, int revents)" 4 |
3706 | .IP "ev_feed_fd_event (loop, int fd, int revents)" 4 |
3504 | .IX Item "ev_feed_fd_event (loop, int fd, int revents)" |
3707 | .IX Item "ev_feed_fd_event (loop, int fd, int revents)" |
3505 | Feed an event on the given fd, as if a file descriptor backend detected |
3708 | Feed an event on the given fd, as if a file descriptor backend detected |
3506 | the given events it. |
3709 | the given events. |
3507 | .IP "ev_feed_signal_event (loop, int signum)" 4 |
3710 | .IP "ev_feed_signal_event (loop, int signum)" 4 |
3508 | .IX Item "ev_feed_signal_event (loop, int signum)" |
3711 | .IX Item "ev_feed_signal_event (loop, int signum)" |
3509 | Feed an event as if the given signal occurred. See also \f(CW\*(C`ev_feed_signal\*(C'\fR, |
3712 | Feed an event as if the given signal occurred. See also \f(CW\*(C`ev_feed_signal\*(C'\fR, |
3510 | which is async-safe. |
3713 | which is async-safe. |
3511 | .SH "COMMON OR USEFUL IDIOMS (OR BOTH)" |
3714 | .SH "COMMON OR USEFUL IDIOMS (OR BOTH)" |
3512 | .IX Header "COMMON OR USEFUL IDIOMS (OR BOTH)" |
3715 | .IX Header "COMMON OR USEFUL IDIOMS (OR BOTH)" |
3513 | This section explains some common idioms that are not immediately |
3716 | This section explains some common idioms that are not immediately |
3514 | obvious. Note that examples are sprinkled over the whole manual, and this |
3717 | obvious. Note that examples are sprinkled over the whole manual, and this |
3515 | section only contains stuff that wouldn't fit anywhere else. |
3718 | section only contains stuff that wouldn't fit anywhere else. |
3516 | .SS "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" |
3719 | .SS "\s-1ASSOCIATING CUSTOM DATA WITH A WATCHER\s0" |
3517 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
3720 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
3518 | Each watcher has, by default, a \f(CW\*(C`void *data\*(C'\fR member that you can read |
3721 | Each watcher has, by default, a \f(CW\*(C`void *data\*(C'\fR member that you can read |
3519 | or modify at any time: libev will completely ignore it. This can be used |
3722 | or modify at any time: libev will completely ignore it. This can be used |
3520 | to associate arbitrary data with your watcher. If you need more data and |
3723 | to associate arbitrary data with your watcher. If you need more data and |
3521 | don't want to allocate memory separately and store a pointer to it in that |
3724 | don't want to allocate memory separately and store a pointer to it in that |
… | |
… | |
3547 | \& } |
3750 | \& } |
3548 | .Ve |
3751 | .Ve |
3549 | .PP |
3752 | .PP |
3550 | More interesting and less C\-conformant ways of casting your callback |
3753 | More interesting and less C\-conformant ways of casting your callback |
3551 | function type instead have been omitted. |
3754 | function type instead have been omitted. |
3552 | .SS "\s-1BUILDING\s0 \s-1YOUR\s0 \s-1OWN\s0 \s-1COMPOSITE\s0 \s-1WATCHERS\s0" |
3755 | .SS "\s-1BUILDING YOUR OWN COMPOSITE WATCHERS\s0" |
3553 | .IX Subsection "BUILDING YOUR OWN COMPOSITE WATCHERS" |
3756 | .IX Subsection "BUILDING YOUR OWN COMPOSITE WATCHERS" |
3554 | Another common scenario is to use some data structure with multiple |
3757 | Another common scenario is to use some data structure with multiple |
3555 | embedded watchers, in effect creating your own watcher that combines |
3758 | embedded watchers, in effect creating your own watcher that combines |
3556 | multiple libev event sources into one \*(L"super-watcher\*(R": |
3759 | multiple libev event sources into one \*(L"super-watcher\*(R": |
3557 | .PP |
3760 | .PP |
… | |
… | |
3585 | \& { |
3788 | \& { |
3586 | \& struct my_biggy big = (struct my_biggy *) |
3789 | \& struct my_biggy big = (struct my_biggy *) |
3587 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
3790 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
3588 | \& } |
3791 | \& } |
3589 | .Ve |
3792 | .Ve |
3590 | .SS "\s-1MODEL/NESTED\s0 \s-1EVENT\s0 \s-1LOOP\s0 \s-1INVOCATIONS\s0 \s-1AND\s0 \s-1EXIT\s0 \s-1CONDITIONS\s0" |
3793 | .SS "\s-1AVOIDING FINISHING BEFORE RETURNING\s0" |
|
|
3794 | .IX Subsection "AVOIDING FINISHING BEFORE RETURNING" |
|
|
3795 | Often you have structures like this in event-based programs: |
|
|
3796 | .PP |
|
|
3797 | .Vb 4 |
|
|
3798 | \& callback () |
|
|
3799 | \& { |
|
|
3800 | \& free (request); |
|
|
3801 | \& } |
|
|
3802 | \& |
|
|
3803 | \& request = start_new_request (..., callback); |
|
|
3804 | .Ve |
|
|
3805 | .PP |
|
|
3806 | The intent is to start some \*(L"lengthy\*(R" operation. The \f(CW\*(C`request\*(C'\fR could be |
|
|
3807 | used to cancel the operation, or do other things with it. |
|
|
3808 | .PP |
|
|
3809 | It's not uncommon to have code paths in \f(CW\*(C`start_new_request\*(C'\fR that |
|
|
3810 | immediately invoke the callback, for example, to report errors. Or you add |
|
|
3811 | some caching layer that finds that it can skip the lengthy aspects of the |
|
|
3812 | operation and simply invoke the callback with the result. |
|
|
3813 | .PP |
|
|
3814 | The problem here is that this will happen \fIbefore\fR \f(CW\*(C`start_new_request\*(C'\fR |
|
|
3815 | has returned, so \f(CW\*(C`request\*(C'\fR is not set. |
|
|
3816 | .PP |
|
|
3817 | Even if you pass the request by some safer means to the callback, you |
|
|
3818 | might want to do something to the request after starting it, such as |
|
|
3819 | canceling it, which probably isn't working so well when the callback has |
|
|
3820 | already been invoked. |
|
|
3821 | .PP |
|
|
3822 | A common way around all these issues is to make sure that |
|
|
3823 | \&\f(CW\*(C`start_new_request\*(C'\fR \fIalways\fR returns before the callback is invoked. If |
|
|
3824 | \&\f(CW\*(C`start_new_request\*(C'\fR immediately knows the result, it can artificially |
|
|
3825 | delay invoking the callback by using a \f(CW\*(C`prepare\*(C'\fR or \f(CW\*(C`idle\*(C'\fR watcher for |
|
|
3826 | example, or more sneakily, by reusing an existing (stopped) watcher and |
|
|
3827 | pushing it into the pending queue: |
|
|
3828 | .PP |
|
|
3829 | .Vb 2 |
|
|
3830 | \& ev_set_cb (watcher, callback); |
|
|
3831 | \& ev_feed_event (EV_A_ watcher, 0); |
|
|
3832 | .Ve |
|
|
3833 | .PP |
|
|
3834 | This way, \f(CW\*(C`start_new_request\*(C'\fR can safely return before the callback is |
|
|
3835 | invoked, while not delaying callback invocation too much. |
|
|
3836 | .SS "\s-1MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS\s0" |
3591 | .IX Subsection "MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS" |
3837 | .IX Subsection "MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS" |
3592 | Often (especially in \s-1GUI\s0 toolkits) there are places where you have |
3838 | Often (especially in \s-1GUI\s0 toolkits) there are places where you have |
3593 | \&\fImodal\fR interaction, which is most easily implemented by recursively |
3839 | \&\fImodal\fR interaction, which is most easily implemented by recursively |
3594 | invoking \f(CW\*(C`ev_run\*(C'\fR. |
3840 | invoking \f(CW\*(C`ev_run\*(C'\fR. |
3595 | .PP |
3841 | .PP |
3596 | This brings the problem of exiting \- a callback might want to finish the |
3842 | This brings the problem of exiting \- a callback might want to finish the |
3597 | main \f(CW\*(C`ev_run\*(C'\fR call, but not the nested one (e.g. user clicked \*(L"Quit\*(R", but |
3843 | main \f(CW\*(C`ev_run\*(C'\fR call, but not the nested one (e.g. user clicked \*(L"Quit\*(R", but |
3598 | a modal \*(L"Are you sure?\*(R" dialog is still waiting), or just the nested one |
3844 | a modal \*(L"Are you sure?\*(R" dialog is still waiting), or just the nested one |
3599 | and not the main one (e.g. user clocked \*(L"Ok\*(R" in a modal dialog), or some |
3845 | and not the main one (e.g. user clocked \*(L"Ok\*(R" in a modal dialog), or some |
3600 | other combination: In these cases, \f(CW\*(C`ev_break\*(C'\fR will not work alone. |
3846 | other combination: In these cases, a simple \f(CW\*(C`ev_break\*(C'\fR will not work. |
3601 | .PP |
3847 | .PP |
3602 | The solution is to maintain \*(L"break this loop\*(R" variable for each \f(CW\*(C`ev_run\*(C'\fR |
3848 | The solution is to maintain \*(L"break this loop\*(R" variable for each \f(CW\*(C`ev_run\*(C'\fR |
3603 | invocation, and use a loop around \f(CW\*(C`ev_run\*(C'\fR until the condition is |
3849 | invocation, and use a loop around \f(CW\*(C`ev_run\*(C'\fR until the condition is |
3604 | triggered, using \f(CW\*(C`EVRUN_ONCE\*(C'\fR: |
3850 | triggered, using \f(CW\*(C`EVRUN_ONCE\*(C'\fR: |
3605 | .PP |
3851 | .PP |
… | |
… | |
3608 | \& int exit_main_loop = 0; |
3854 | \& int exit_main_loop = 0; |
3609 | \& |
3855 | \& |
3610 | \& while (!exit_main_loop) |
3856 | \& while (!exit_main_loop) |
3611 | \& ev_run (EV_DEFAULT_ EVRUN_ONCE); |
3857 | \& ev_run (EV_DEFAULT_ EVRUN_ONCE); |
3612 | \& |
3858 | \& |
3613 | \& // in a model watcher |
3859 | \& // in a modal watcher |
3614 | \& int exit_nested_loop = 0; |
3860 | \& int exit_nested_loop = 0; |
3615 | \& |
3861 | \& |
3616 | \& while (!exit_nested_loop) |
3862 | \& while (!exit_nested_loop) |
3617 | \& ev_run (EV_A_ EVRUN_ONCE); |
3863 | \& ev_run (EV_A_ EVRUN_ONCE); |
3618 | .Ve |
3864 | .Ve |
… | |
… | |
3627 | \& exit_main_loop = 1; |
3873 | \& exit_main_loop = 1; |
3628 | \& |
3874 | \& |
3629 | \& // exit both |
3875 | \& // exit both |
3630 | \& exit_main_loop = exit_nested_loop = 1; |
3876 | \& exit_main_loop = exit_nested_loop = 1; |
3631 | .Ve |
3877 | .Ve |
3632 | .SS "\s-1THREAD\s0 \s-1LOCKING\s0 \s-1EXAMPLE\s0" |
3878 | .SS "\s-1THREAD LOCKING EXAMPLE\s0" |
3633 | .IX Subsection "THREAD LOCKING EXAMPLE" |
3879 | .IX Subsection "THREAD LOCKING EXAMPLE" |
3634 | Here is a fictitious example of how to run an event loop in a different |
3880 | Here is a fictitious example of how to run an event loop in a different |
3635 | thread from where callbacks are being invoked and watchers are |
3881 | thread from where callbacks are being invoked and watchers are |
3636 | created/added/removed. |
3882 | created/added/removed. |
3637 | .PP |
3883 | .PP |
… | |
… | |
3778 | .PP |
4024 | .PP |
3779 | Note that sending the \f(CW\*(C`ev_async\*(C'\fR watcher is required because otherwise |
4025 | Note that sending the \f(CW\*(C`ev_async\*(C'\fR watcher is required because otherwise |
3780 | an event loop currently blocking in the kernel will have no knowledge |
4026 | an event loop currently blocking in the kernel will have no knowledge |
3781 | about the newly added timer. By waking up the loop it will pick up any new |
4027 | about the newly added timer. By waking up the loop it will pick up any new |
3782 | watchers in the next event loop iteration. |
4028 | watchers in the next event loop iteration. |
3783 | .SS "\s-1THREADS\s0, \s-1COROUTINES\s0, \s-1CONTINUATIONS\s0, \s-1QUEUES\s0... \s-1INSTEAD\s0 \s-1OF\s0 \s-1CALLBACKS\s0" |
4029 | .SS "\s-1THREADS, COROUTINES, CONTINUATIONS, QUEUES... INSTEAD OF CALLBACKS\s0" |
3784 | .IX Subsection "THREADS, COROUTINES, CONTINUATIONS, QUEUES... INSTEAD OF CALLBACKS" |
4030 | .IX Subsection "THREADS, COROUTINES, CONTINUATIONS, QUEUES... INSTEAD OF CALLBACKS" |
3785 | While the overhead of a callback that e.g. schedules a thread is small, it |
4031 | While the overhead of a callback that e.g. schedules a thread is small, it |
3786 | is still an overhead. If you embed libev, and your main usage is with some |
4032 | is still an overhead. If you embed libev, and your main usage is with some |
3787 | kind of threads or coroutines, you might want to customise libev so that |
4033 | kind of threads or coroutines, you might want to customise libev so that |
3788 | doesn't need callbacks anymore. |
4034 | doesn't need callbacks anymore. |
… | |
… | |
3810 | .PP |
4056 | .PP |
3811 | .Vb 6 |
4057 | .Vb 6 |
3812 | \& void |
4058 | \& void |
3813 | \& wait_for_event (ev_watcher *w) |
4059 | \& wait_for_event (ev_watcher *w) |
3814 | \& { |
4060 | \& { |
3815 | \& ev_cb_set (w) = current_coro; |
4061 | \& ev_set_cb (w, current_coro); |
3816 | \& switch_to (libev_coro); |
4062 | \& switch_to (libev_coro); |
3817 | \& } |
4063 | \& } |
3818 | .Ve |
4064 | .Ve |
3819 | .PP |
4065 | .PP |
3820 | That basically suspends the coroutine inside \f(CW\*(C`wait_for_event\*(C'\fR and |
4066 | That basically suspends the coroutine inside \f(CW\*(C`wait_for_event\*(C'\fR and |
3821 | continues the libev coroutine, which, when appropriate, switches back to |
4067 | continues the libev coroutine, which, when appropriate, switches back to |
3822 | this or any other coroutine. I am sure if you sue this your own :) |
4068 | this or any other coroutine. |
3823 | .PP |
4069 | .PP |
3824 | You can do similar tricks if you have, say, threads with an event queue \- |
4070 | You can do similar tricks if you have, say, threads with an event queue \- |
3825 | instead of storing a coroutine, you store the queue object and instead of |
4071 | instead of storing a coroutine, you store the queue object and instead of |
3826 | switching to a coroutine, you push the watcher onto the queue and notify |
4072 | switching to a coroutine, you push the watcher onto the queue and notify |
3827 | any waiters. |
4073 | any waiters. |
3828 | .PP |
4074 | .PP |
3829 | To embed libev, see \s-1EMBEDDING\s0, but in short, it's easiest to create two |
4075 | To embed libev, see \*(L"\s-1EMBEDDING\*(R"\s0, but in short, it's easiest to create two |
3830 | files, \fImy_ev.h\fR and \fImy_ev.c\fR that include the respective libev files: |
4076 | files, \fImy_ev.h\fR and \fImy_ev.c\fR that include the respective libev files: |
3831 | .PP |
4077 | .PP |
3832 | .Vb 4 |
4078 | .Vb 4 |
3833 | \& // my_ev.h |
4079 | \& // my_ev.h |
3834 | \& #define EV_CB_DECLARE(type) struct my_coro *cb; |
4080 | \& #define EV_CB_DECLARE(type) struct my_coro *cb; |
3835 | \& #define EV_CB_INVOKE(watcher) switch_to ((watcher)\->cb); |
4081 | \& #define EV_CB_INVOKE(watcher) switch_to ((watcher)\->cb) |
3836 | \& #include "../libev/ev.h" |
4082 | \& #include "../libev/ev.h" |
3837 | \& |
4083 | \& |
3838 | \& // my_ev.c |
4084 | \& // my_ev.c |
3839 | \& #define EV_H "my_ev.h" |
4085 | \& #define EV_H "my_ev.h" |
3840 | \& #include "../libev/ev.c" |
4086 | \& #include "../libev/ev.c" |
… | |
… | |
3873 | .IP "\(bu" 4 |
4119 | .IP "\(bu" 4 |
3874 | The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need |
4120 | The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need |
3875 | to use the libev header file and library. |
4121 | to use the libev header file and library. |
3876 | .SH "\*(C+ SUPPORT" |
4122 | .SH "\*(C+ SUPPORT" |
3877 | .IX Header " SUPPORT" |
4123 | .IX Header " SUPPORT" |
|
|
4124 | .SS "C \s-1API\s0" |
|
|
4125 | .IX Subsection "C API" |
|
|
4126 | The normal C \s-1API\s0 should work fine when used from \*(C+: both ev.h and the |
|
|
4127 | libev sources can be compiled as \*(C+. Therefore, code that uses the C \s-1API\s0 |
|
|
4128 | will work fine. |
|
|
4129 | .PP |
|
|
4130 | Proper exception specifications might have to be added to callbacks passed |
|
|
4131 | to libev: exceptions may be thrown only from watcher callbacks, all other |
|
|
4132 | callbacks (allocator, syserr, loop acquire/release and periodic reschedule |
|
|
4133 | callbacks) must not throw exceptions, and might need a \f(CW\*(C`noexcept\*(C'\fR |
|
|
4134 | specification. If you have code that needs to be compiled as both C and |
|
|
4135 | \&\*(C+ you can use the \f(CW\*(C`EV_NOEXCEPT\*(C'\fR macro for this: |
|
|
4136 | .PP |
|
|
4137 | .Vb 6 |
|
|
4138 | \& static void |
|
|
4139 | \& fatal_error (const char *msg) EV_NOEXCEPT |
|
|
4140 | \& { |
|
|
4141 | \& perror (msg); |
|
|
4142 | \& abort (); |
|
|
4143 | \& } |
|
|
4144 | \& |
|
|
4145 | \& ... |
|
|
4146 | \& ev_set_syserr_cb (fatal_error); |
|
|
4147 | .Ve |
|
|
4148 | .PP |
|
|
4149 | The only \s-1API\s0 functions that can currently throw exceptions are \f(CW\*(C`ev_run\*(C'\fR, |
|
|
4150 | \&\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 |
|
|
4151 | because it runs cleanup watchers). |
|
|
4152 | .PP |
|
|
4153 | Throwing exceptions in watcher callbacks is only supported if libev itself |
|
|
4154 | is compiled with a \*(C+ compiler or your C and \*(C+ environments allow |
|
|
4155 | throwing exceptions through C libraries (most do). |
|
|
4156 | .SS "\*(C+ \s-1API\s0" |
|
|
4157 | .IX Subsection " API" |
3878 | Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow |
4158 | Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow |
3879 | you to use some convenience methods to start/stop watchers and also change |
4159 | you to use some convenience methods to start/stop watchers and also change |
3880 | the callback model to a model using method callbacks on objects. |
4160 | the callback model to a model using method callbacks on objects. |
3881 | .PP |
4161 | .PP |
3882 | To use it, |
4162 | To use it, |
… | |
… | |
3898 | Currently, functions, static and non-static member functions and classes |
4178 | Currently, functions, static and non-static member functions and classes |
3899 | with \f(CW\*(C`operator ()\*(C'\fR can be used as callbacks. Other types should be easy |
4179 | with \f(CW\*(C`operator ()\*(C'\fR can be used as callbacks. Other types should be easy |
3900 | to add as long as they only need one additional pointer for context. If |
4180 | to add as long as they only need one additional pointer for context. If |
3901 | you need support for other types of functors please contact the author |
4181 | you need support for other types of functors please contact the author |
3902 | (preferably after implementing it). |
4182 | (preferably after implementing it). |
|
|
4183 | .PP |
|
|
4184 | For all this to work, your \*(C+ compiler either has to use the same calling |
|
|
4185 | conventions as your C compiler (for static member functions), or you have |
|
|
4186 | to embed libev and compile libev itself as \*(C+. |
3903 | .PP |
4187 | .PP |
3904 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
4188 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
3905 | .ie n .IP """ev::READ"", ""ev::WRITE"" etc." 4 |
4189 | .ie n .IP """ev::READ"", ""ev::WRITE"" etc." 4 |
3906 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
4190 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
3907 | .IX Item "ev::READ, ev::WRITE etc." |
4191 | .IX Item "ev::READ, ev::WRITE etc." |
… | |
… | |
3915 | .el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4 |
4199 | .el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4 |
3916 | .IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc." |
4200 | .IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc." |
3917 | For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of |
4201 | For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of |
3918 | the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR |
4202 | the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR |
3919 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
4203 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
3920 | defines by many implementations. |
4204 | defined by many implementations. |
3921 | .Sp |
4205 | .Sp |
3922 | All of those classes have these methods: |
4206 | All of those classes have these methods: |
3923 | .RS 4 |
4207 | .RS 4 |
3924 | .IP "ev::TYPE::TYPE ()" 4 |
4208 | .IP "ev::TYPE::TYPE ()" 4 |
3925 | .IX Item "ev::TYPE::TYPE ()" |
4209 | .IX Item "ev::TYPE::TYPE ()" |
… | |
… | |
3988 | \& void operator() (ev::io &w, int revents) |
4272 | \& void operator() (ev::io &w, int revents) |
3989 | \& { |
4273 | \& { |
3990 | \& ... |
4274 | \& ... |
3991 | \& } |
4275 | \& } |
3992 | \& } |
4276 | \& } |
3993 | \& |
4277 | \& |
3994 | \& myfunctor f; |
4278 | \& myfunctor f; |
3995 | \& |
4279 | \& |
3996 | \& ev::io w; |
4280 | \& ev::io w; |
3997 | \& w.set (&f); |
4281 | \& w.set (&f); |
3998 | .Ve |
4282 | .Ve |
… | |
… | |
4016 | .IX Item "w->set (loop)" |
4300 | .IX Item "w->set (loop)" |
4017 | Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only |
4301 | Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only |
4018 | do this when the watcher is inactive (and not pending either). |
4302 | do this when the watcher is inactive (and not pending either). |
4019 | .IP "w\->set ([arguments])" 4 |
4303 | .IP "w\->set ([arguments])" 4 |
4020 | .IX Item "w->set ([arguments])" |
4304 | .IX Item "w->set ([arguments])" |
4021 | Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same arguments. Either this |
4305 | Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR (except for \f(CW\*(C`ev::embed\*(C'\fR watchers>), |
4022 | method or a suitable start method must be called at least once. Unlike the |
4306 | with the same arguments. Either this method or a suitable start method |
4023 | C counterpart, an active watcher gets automatically stopped and restarted |
4307 | must be called at least once. Unlike the C counterpart, an active watcher |
4024 | when reconfiguring it with this method. |
4308 | gets automatically stopped and restarted when reconfiguring it with this |
|
|
4309 | method. |
|
|
4310 | .Sp |
|
|
4311 | For \f(CW\*(C`ev::embed\*(C'\fR watchers this method is called \f(CW\*(C`set_embed\*(C'\fR, to avoid |
|
|
4312 | clashing with the \f(CW\*(C`set (loop)\*(C'\fR method. |
4025 | .IP "w\->start ()" 4 |
4313 | .IP "w\->start ()" 4 |
4026 | .IX Item "w->start ()" |
4314 | .IX Item "w->start ()" |
4027 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the |
4315 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the |
4028 | constructor already stores the event loop. |
4316 | constructor already stores the event loop. |
4029 | .IP "w\->start ([arguments])" 4 |
4317 | .IP "w\->start ([arguments])" 4 |
… | |
… | |
4056 | .PP |
4344 | .PP |
4057 | .Vb 5 |
4345 | .Vb 5 |
4058 | \& class myclass |
4346 | \& class myclass |
4059 | \& { |
4347 | \& { |
4060 | \& ev::io io ; void io_cb (ev::io &w, int revents); |
4348 | \& ev::io io ; void io_cb (ev::io &w, int revents); |
4061 | \& ev::io2 io2 ; void io2_cb (ev::io &w, int revents); |
4349 | \& ev::io io2 ; void io2_cb (ev::io &w, int revents); |
4062 | \& ev::idle idle; void idle_cb (ev::idle &w, int revents); |
4350 | \& ev::idle idle; void idle_cb (ev::idle &w, int revents); |
4063 | \& |
4351 | \& |
4064 | \& myclass (int fd) |
4352 | \& myclass (int fd) |
4065 | \& { |
4353 | \& { |
4066 | \& io .set <myclass, &myclass::io_cb > (this); |
4354 | \& io .set <myclass, &myclass::io_cb > (this); |
… | |
… | |
4087 | there are additional modules that implement libev-compatible interfaces |
4375 | there are additional modules that implement libev-compatible interfaces |
4088 | 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), |
4376 | 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), |
4089 | \&\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 |
4377 | \&\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 |
4090 | and \f(CW\*(C`EV::Glib\*(C'\fR). |
4378 | and \f(CW\*(C`EV::Glib\*(C'\fR). |
4091 | .Sp |
4379 | .Sp |
4092 | It can be found and installed via \s-1CPAN\s0, its homepage is at |
4380 | It can be found and installed via \s-1CPAN,\s0 its homepage is at |
4093 | <http://software.schmorp.de/pkg/EV>. |
4381 | <http://software.schmorp.de/pkg/EV>. |
4094 | .IP "Python" 4 |
4382 | .IP "Python" 4 |
4095 | .IX Item "Python" |
4383 | .IX Item "Python" |
4096 | Python bindings can be found at <http://code.google.com/p/pyev/>. It |
4384 | Python bindings can be found at <http://code.google.com/p/pyev/>. It |
4097 | seems to be quite complete and well-documented. |
4385 | seems to be quite complete and well-documented. |
… | |
… | |
4109 | A haskell binding to libev is available at |
4397 | A haskell binding to libev is available at |
4110 | <http://hackage.haskell.org/cgi\-bin/hackage\-scripts/package/hlibev>. |
4398 | <http://hackage.haskell.org/cgi\-bin/hackage\-scripts/package/hlibev>. |
4111 | .IP "D" 4 |
4399 | .IP "D" 4 |
4112 | .IX Item "D" |
4400 | .IX Item "D" |
4113 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
4401 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
4114 | be found at <http://proj.llucax.com.ar/wiki/evd>. |
4402 | be found at <http://www.llucax.com.ar/proj/ev.d/index.html>. |
4115 | .IP "Ocaml" 4 |
4403 | .IP "Ocaml" 4 |
4116 | .IX Item "Ocaml" |
4404 | .IX Item "Ocaml" |
4117 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
4405 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
4118 | <http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/>. |
4406 | <http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/>. |
4119 | .IP "Lua" 4 |
4407 | .IP "Lua" 4 |
4120 | .IX Item "Lua" |
4408 | .IX Item "Lua" |
4121 | Brian Maher has written a partial interface to libev for lua (at the |
4409 | Brian Maher has written a partial interface to libev for lua (at the |
4122 | time of this writing, only \f(CW\*(C`ev_io\*(C'\fR and \f(CW\*(C`ev_timer\*(C'\fR), to be found at |
4410 | time of this writing, only \f(CW\*(C`ev_io\*(C'\fR and \f(CW\*(C`ev_timer\*(C'\fR), to be found at |
4123 | <http://github.com/brimworks/lua\-ev>. |
4411 | <http://github.com/brimworks/lua\-ev>. |
|
|
4412 | .IP "Javascript" 4 |
|
|
4413 | .IX Item "Javascript" |
|
|
4414 | Node.js (<http://nodejs.org>) uses libev as the underlying event library. |
|
|
4415 | .IP "Others" 4 |
|
|
4416 | .IX Item "Others" |
|
|
4417 | There are others, and I stopped counting. |
4124 | .SH "MACRO MAGIC" |
4418 | .SH "MACRO MAGIC" |
4125 | .IX Header "MACRO MAGIC" |
4419 | .IX Header "MACRO MAGIC" |
4126 | Libev can be compiled with a variety of options, the most fundamental |
4420 | Libev can be compiled with a variety of options, the most fundamental |
4127 | of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) |
4421 | of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) |
4128 | functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
4422 | functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
… | |
… | |
4163 | suitable for use with \f(CW\*(C`EV_A\*(C'\fR. |
4457 | suitable for use with \f(CW\*(C`EV_A\*(C'\fR. |
4164 | .ie n .IP """EV_DEFAULT"", ""EV_DEFAULT_""" 4 |
4458 | .ie n .IP """EV_DEFAULT"", ""EV_DEFAULT_""" 4 |
4165 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
4459 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
4166 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
4460 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
4167 | Similar to the other two macros, this gives you the value of the default |
4461 | Similar to the other two macros, this gives you the value of the default |
4168 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). |
4462 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). The default loop |
|
|
4463 | will be initialised if it isn't already initialised. |
|
|
4464 | .Sp |
|
|
4465 | For non-multiplicity builds, these macros do nothing, so you always have |
|
|
4466 | to initialise the loop somewhere. |
4169 | .ie n .IP """EV_DEFAULT_UC"", ""EV_DEFAULT_UC_""" 4 |
4467 | .ie n .IP """EV_DEFAULT_UC"", ""EV_DEFAULT_UC_""" 4 |
4170 | .el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4 |
4468 | .el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4 |
4171 | .IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_" |
4469 | .IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_" |
4172 | Usage identical to \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR, but requires that the |
4470 | Usage identical to \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR, but requires that the |
4173 | default loop has been initialised (\f(CW\*(C`UC\*(C'\fR == unchecked). Their behaviour |
4471 | default loop has been initialised (\f(CW\*(C`UC\*(C'\fR == unchecked). Their behaviour |
… | |
… | |
4207 | .SS "\s-1FILESETS\s0" |
4505 | .SS "\s-1FILESETS\s0" |
4208 | .IX Subsection "FILESETS" |
4506 | .IX Subsection "FILESETS" |
4209 | Depending on what features you need you need to include one or more sets of files |
4507 | Depending on what features you need you need to include one or more sets of files |
4210 | in your application. |
4508 | in your application. |
4211 | .PP |
4509 | .PP |
4212 | \fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR |
4510 | \fI\s-1CORE EVENT LOOP\s0\fR |
4213 | .IX Subsection "CORE EVENT LOOP" |
4511 | .IX Subsection "CORE EVENT LOOP" |
4214 | .PP |
4512 | .PP |
4215 | To include only the libev core (all the \f(CW\*(C`ev_*\*(C'\fR functions), with manual |
4513 | To include only the libev core (all the \f(CW\*(C`ev_*\*(C'\fR functions), with manual |
4216 | configuration (no autoconf): |
4514 | configuration (no autoconf): |
4217 | .PP |
4515 | .PP |
… | |
… | |
4220 | \& #include "ev.c" |
4518 | \& #include "ev.c" |
4221 | .Ve |
4519 | .Ve |
4222 | .PP |
4520 | .PP |
4223 | This will automatically include \fIev.h\fR, too, and should be done in a |
4521 | This will automatically include \fIev.h\fR, too, and should be done in a |
4224 | single C source file only to provide the function implementations. To use |
4522 | single C source file only to provide the function implementations. To use |
4225 | it, do the same for \fIev.h\fR in all files wishing to use this \s-1API\s0 (best |
4523 | it, do the same for \fIev.h\fR in all files wishing to use this \s-1API \s0(best |
4226 | done by writing a wrapper around \fIev.h\fR that you can include instead and |
4524 | done by writing a wrapper around \fIev.h\fR that you can include instead and |
4227 | where you can put other configuration options): |
4525 | where you can put other configuration options): |
4228 | .PP |
4526 | .PP |
4229 | .Vb 2 |
4527 | .Vb 2 |
4230 | \& #define EV_STANDALONE 1 |
4528 | \& #define EV_STANDALONE 1 |
… | |
… | |
4244 | \& ev_vars.h |
4542 | \& ev_vars.h |
4245 | \& ev_wrap.h |
4543 | \& ev_wrap.h |
4246 | \& |
4544 | \& |
4247 | \& ev_win32.c required on win32 platforms only |
4545 | \& ev_win32.c required on win32 platforms only |
4248 | \& |
4546 | \& |
4249 | \& ev_select.c only when select backend is enabled (which is enabled by default) |
4547 | \& ev_select.c only when select backend is enabled |
4250 | \& ev_poll.c only when poll backend is enabled (disabled by default) |
4548 | \& ev_poll.c only when poll backend is enabled |
4251 | \& ev_epoll.c only when the epoll backend is enabled (disabled by default) |
4549 | \& ev_epoll.c only when the epoll backend is enabled |
4252 | \& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
4550 | \& ev_kqueue.c only when the kqueue backend is enabled |
4253 | \& ev_port.c only when the solaris port backend is enabled (disabled by default) |
4551 | \& ev_port.c only when the solaris port backend is enabled |
4254 | .Ve |
4552 | .Ve |
4255 | .PP |
4553 | .PP |
4256 | \&\fIev.c\fR includes the backend files directly when enabled, so you only need |
4554 | \&\fIev.c\fR includes the backend files directly when enabled, so you only need |
4257 | to compile this single file. |
4555 | to compile this single file. |
4258 | .PP |
4556 | .PP |
4259 | \fI\s-1LIBEVENT\s0 \s-1COMPATIBILITY\s0 \s-1API\s0\fR |
4557 | \fI\s-1LIBEVENT COMPATIBILITY API\s0\fR |
4260 | .IX Subsection "LIBEVENT COMPATIBILITY API" |
4558 | .IX Subsection "LIBEVENT COMPATIBILITY API" |
4261 | .PP |
4559 | .PP |
4262 | To include the libevent compatibility \s-1API\s0, also include: |
4560 | To include the libevent compatibility \s-1API,\s0 also include: |
4263 | .PP |
4561 | .PP |
4264 | .Vb 1 |
4562 | .Vb 1 |
4265 | \& #include "event.c" |
4563 | \& #include "event.c" |
4266 | .Ve |
4564 | .Ve |
4267 | .PP |
4565 | .PP |
… | |
… | |
4269 | .PP |
4567 | .PP |
4270 | .Vb 1 |
4568 | .Vb 1 |
4271 | \& #include "event.h" |
4569 | \& #include "event.h" |
4272 | .Ve |
4570 | .Ve |
4273 | .PP |
4571 | .PP |
4274 | in the files that want to use the libevent \s-1API\s0. This also includes \fIev.h\fR. |
4572 | in the files that want to use the libevent \s-1API.\s0 This also includes \fIev.h\fR. |
4275 | .PP |
4573 | .PP |
4276 | You need the following additional files for this: |
4574 | You need the following additional files for this: |
4277 | .PP |
4575 | .PP |
4278 | .Vb 2 |
4576 | .Vb 2 |
4279 | \& event.h |
4577 | \& event.h |
4280 | \& event.c |
4578 | \& event.c |
4281 | .Ve |
4579 | .Ve |
4282 | .PP |
4580 | .PP |
4283 | \fI\s-1AUTOCONF\s0 \s-1SUPPORT\s0\fR |
4581 | \fI\s-1AUTOCONF SUPPORT\s0\fR |
4284 | .IX Subsection "AUTOCONF SUPPORT" |
4582 | .IX Subsection "AUTOCONF SUPPORT" |
4285 | .PP |
4583 | .PP |
4286 | Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your configuration in |
4584 | Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your configuration in |
4287 | whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your |
4585 | whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your |
4288 | \&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then |
4586 | \&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then |
… | |
… | |
4291 | For this of course you need the m4 file: |
4589 | For this of course you need the m4 file: |
4292 | .PP |
4590 | .PP |
4293 | .Vb 1 |
4591 | .Vb 1 |
4294 | \& libev.m4 |
4592 | \& libev.m4 |
4295 | .Ve |
4593 | .Ve |
4296 | .SS "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" |
4594 | .SS "\s-1PREPROCESSOR SYMBOLS/MACROS\s0" |
4297 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
4595 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
4298 | Libev can be configured via a variety of preprocessor symbols you have to |
4596 | Libev can be configured via a variety of preprocessor symbols you have to |
4299 | define before including (or compiling) any of its files. The default in |
4597 | define before including (or compiling) any of its files. The default in |
4300 | the absence of autoconf is documented for every option. |
4598 | the absence of autoconf is documented for every option. |
4301 | .PP |
4599 | .PP |
4302 | Symbols marked with \*(L"(h)\*(R" do not change the \s-1ABI\s0, and can have different |
4600 | Symbols marked with \*(L"(h)\*(R" do not change the \s-1ABI,\s0 and can have different |
4303 | values when compiling libev vs. including \fIev.h\fR, so it is permissible |
4601 | values when compiling libev vs. including \fIev.h\fR, so it is permissible |
4304 | to redefine them before including \fIev.h\fR without breaking compatibility |
4602 | to redefine them before including \fIev.h\fR without breaking compatibility |
4305 | to a compiled library. All other symbols change the \s-1ABI\s0, which means all |
4603 | to a compiled library. All other symbols change the \s-1ABI,\s0 which means all |
4306 | users of libev and the libev code itself must be compiled with compatible |
4604 | users of libev and the libev code itself must be compiled with compatible |
4307 | settings. |
4605 | settings. |
4308 | .IP "\s-1EV_COMPAT3\s0 (h)" 4 |
4606 | .IP "\s-1EV_COMPAT3 \s0(h)" 4 |
4309 | .IX Item "EV_COMPAT3 (h)" |
4607 | .IX Item "EV_COMPAT3 (h)" |
4310 | Backwards compatibility is a major concern for libev. This is why this |
4608 | Backwards compatibility is a major concern for libev. This is why this |
4311 | release of libev comes with wrappers for the functions and symbols that |
4609 | release of libev comes with wrappers for the functions and symbols that |
4312 | have been renamed between libev version 3 and 4. |
4610 | have been renamed between libev version 3 and 4. |
4313 | .Sp |
4611 | .Sp |
… | |
… | |
4318 | typedef in that case. |
4616 | typedef in that case. |
4319 | .Sp |
4617 | .Sp |
4320 | In some future version, the default for \f(CW\*(C`EV_COMPAT3\*(C'\fR will become \f(CW0\fR, |
4618 | In some future version, the default for \f(CW\*(C`EV_COMPAT3\*(C'\fR will become \f(CW0\fR, |
4321 | and in some even more future version the compatibility code will be |
4619 | and in some even more future version the compatibility code will be |
4322 | removed completely. |
4620 | removed completely. |
4323 | .IP "\s-1EV_STANDALONE\s0 (h)" 4 |
4621 | .IP "\s-1EV_STANDALONE \s0(h)" 4 |
4324 | .IX Item "EV_STANDALONE (h)" |
4622 | .IX Item "EV_STANDALONE (h)" |
4325 | Must always be \f(CW1\fR if you do not use autoconf configuration, which |
4623 | Must always be \f(CW1\fR if you do not use autoconf configuration, which |
4326 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
4624 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
4327 | implementations for some libevent functions (such as logging, which is not |
4625 | implementations for some libevent functions (such as logging, which is not |
4328 | supported). It will also not define any of the structs usually found in |
4626 | supported). It will also not define any of the structs usually found in |
4329 | \&\fIevent.h\fR that are not directly supported by the libev core alone. |
4627 | \&\fIevent.h\fR that are not directly supported by the libev core alone. |
4330 | .Sp |
4628 | .Sp |
4331 | In standalone mode, libev will still try to automatically deduce the |
4629 | In standalone mode, libev will still try to automatically deduce the |
4332 | configuration, but has to be more conservative. |
4630 | configuration, but has to be more conservative. |
|
|
4631 | .IP "\s-1EV_USE_FLOOR\s0" 4 |
|
|
4632 | .IX Item "EV_USE_FLOOR" |
|
|
4633 | If defined to be \f(CW1\fR, libev will use the \f(CW\*(C`floor ()\*(C'\fR function for its |
|
|
4634 | periodic reschedule calculations, otherwise libev will fall back on a |
|
|
4635 | portable (slower) implementation. If you enable this, you usually have to |
|
|
4636 | link against libm or something equivalent. Enabling this when the \f(CW\*(C`floor\*(C'\fR |
|
|
4637 | function is not available will fail, so the safe default is to not enable |
|
|
4638 | this. |
4333 | .IP "\s-1EV_USE_MONOTONIC\s0" 4 |
4639 | .IP "\s-1EV_USE_MONOTONIC\s0" 4 |
4334 | .IX Item "EV_USE_MONOTONIC" |
4640 | .IX Item "EV_USE_MONOTONIC" |
4335 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
4641 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
4336 | monotonic clock option at both compile time and runtime. Otherwise no |
4642 | monotonic clock option at both compile time and runtime. Otherwise no |
4337 | use of the monotonic clock option will be attempted. If you enable this, |
4643 | use of the monotonic clock option will be attempted. If you enable this, |
… | |
… | |
4411 | .IX Item "EV_WIN32_CLOSE_FD(fd)" |
4717 | .IX Item "EV_WIN32_CLOSE_FD(fd)" |
4412 | If programs implement their own fd to handle mapping on win32, then this |
4718 | If programs implement their own fd to handle mapping on win32, then this |
4413 | macro can be used to override the \f(CW\*(C`close\*(C'\fR function, useful to unregister |
4719 | macro can be used to override the \f(CW\*(C`close\*(C'\fR function, useful to unregister |
4414 | file descriptors again. Note that the replacement function has to close |
4720 | file descriptors again. Note that the replacement function has to close |
4415 | the underlying \s-1OS\s0 handle. |
4721 | the underlying \s-1OS\s0 handle. |
|
|
4722 | .IP "\s-1EV_USE_WSASOCKET\s0" 4 |
|
|
4723 | .IX Item "EV_USE_WSASOCKET" |
|
|
4724 | If defined to be \f(CW1\fR, libev will use \f(CW\*(C`WSASocket\*(C'\fR to create its internal |
|
|
4725 | communication socket, which works better in some environments. Otherwise, |
|
|
4726 | the normal \f(CW\*(C`socket\*(C'\fR function will be used, which works better in other |
|
|
4727 | environments. |
4416 | .IP "\s-1EV_USE_POLL\s0" 4 |
4728 | .IP "\s-1EV_USE_POLL\s0" 4 |
4417 | .IX Item "EV_USE_POLL" |
4729 | .IX Item "EV_USE_POLL" |
4418 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
4730 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
4419 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
4731 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
4420 | takes precedence over select. |
4732 | takes precedence over select. |
… | |
… | |
4449 | .IX Item "EV_USE_INOTIFY" |
4761 | .IX Item "EV_USE_INOTIFY" |
4450 | If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify |
4762 | If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify |
4451 | interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will |
4763 | interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will |
4452 | be detected at runtime. If undefined, it will be enabled if the headers |
4764 | be detected at runtime. If undefined, it will be enabled if the headers |
4453 | indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
4765 | indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
|
|
4766 | .IP "\s-1EV_NO_SMP\s0" 4 |
|
|
4767 | .IX Item "EV_NO_SMP" |
|
|
4768 | If defined to be \f(CW1\fR, libev will assume that memory is always coherent |
|
|
4769 | between threads, that is, threads can be used, but threads never run on |
|
|
4770 | different cpus (or different cpu cores). This reduces dependencies |
|
|
4771 | and makes libev faster. |
|
|
4772 | .IP "\s-1EV_NO_THREADS\s0" 4 |
|
|
4773 | .IX Item "EV_NO_THREADS" |
|
|
4774 | If defined to be \f(CW1\fR, libev will assume that it will never be called from |
|
|
4775 | different threads (that includes signal handlers), which is a stronger |
|
|
4776 | assumption than \f(CW\*(C`EV_NO_SMP\*(C'\fR, above. This reduces dependencies and makes |
|
|
4777 | libev faster. |
4454 | .IP "\s-1EV_ATOMIC_T\s0" 4 |
4778 | .IP "\s-1EV_ATOMIC_T\s0" 4 |
4455 | .IX Item "EV_ATOMIC_T" |
4779 | .IX Item "EV_ATOMIC_T" |
4456 | Libev requires an integer type (suitable for storing \f(CW0\fR or \f(CW1\fR) whose |
4780 | Libev requires an integer type (suitable for storing \f(CW0\fR or \f(CW1\fR) whose |
4457 | access is atomic with respect to other threads or signal contexts. No such |
4781 | access is atomic with respect to other threads or signal contexts. No |
4458 | type is easily found in the C language, so you can provide your own type |
4782 | such type is easily found in the C language, so you can provide your own |
4459 | that you know is safe for your purposes. It is used both for signal handler \*(L"locking\*(R" |
4783 | type that you know is safe for your purposes. It is used both for signal |
4460 | as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR watchers. |
4784 | handler \*(L"locking\*(R" as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR |
|
|
4785 | watchers. |
4461 | .Sp |
4786 | .Sp |
4462 | In the absence of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR |
4787 | In the absence of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR |
4463 | (from \fIsignal.h\fR), which is usually good enough on most platforms. |
4788 | (from \fIsignal.h\fR), which is usually good enough on most platforms. |
4464 | .IP "\s-1EV_H\s0 (h)" 4 |
4789 | .IP "\s-1EV_H \s0(h)" 4 |
4465 | .IX Item "EV_H (h)" |
4790 | .IX Item "EV_H (h)" |
4466 | The name of the \fIev.h\fR header file used to include it. The default if |
4791 | The name of the \fIev.h\fR header file used to include it. The default if |
4467 | undefined is \f(CW"ev.h"\fR in \fIevent.h\fR, \fIev.c\fR and \fIev++.h\fR. This can be |
4792 | undefined is \f(CW"ev.h"\fR in \fIevent.h\fR, \fIev.c\fR and \fIev++.h\fR. This can be |
4468 | used to virtually rename the \fIev.h\fR header file in case of conflicts. |
4793 | used to virtually rename the \fIev.h\fR header file in case of conflicts. |
4469 | .IP "\s-1EV_CONFIG_H\s0 (h)" 4 |
4794 | .IP "\s-1EV_CONFIG_H \s0(h)" 4 |
4470 | .IX Item "EV_CONFIG_H (h)" |
4795 | .IX Item "EV_CONFIG_H (h)" |
4471 | If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override |
4796 | If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override |
4472 | \&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to |
4797 | \&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to |
4473 | \&\f(CW\*(C`EV_H\*(C'\fR, above. |
4798 | \&\f(CW\*(C`EV_H\*(C'\fR, above. |
4474 | .IP "\s-1EV_EVENT_H\s0 (h)" 4 |
4799 | .IP "\s-1EV_EVENT_H \s0(h)" 4 |
4475 | .IX Item "EV_EVENT_H (h)" |
4800 | .IX Item "EV_EVENT_H (h)" |
4476 | Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea |
4801 | Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea |
4477 | of how the \fIevent.h\fR header can be found, the default is \f(CW"event.h"\fR. |
4802 | of how the \fIevent.h\fR header can be found, the default is \f(CW"event.h"\fR. |
4478 | .IP "\s-1EV_PROTOTYPES\s0 (h)" 4 |
4803 | .IP "\s-1EV_PROTOTYPES \s0(h)" 4 |
4479 | .IX Item "EV_PROTOTYPES (h)" |
4804 | .IX Item "EV_PROTOTYPES (h)" |
4480 | If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function |
4805 | If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function |
4481 | prototypes, but still define all the structs and other symbols. This is |
4806 | prototypes, but still define all the structs and other symbols. This is |
4482 | occasionally useful if you want to provide your own wrapper functions |
4807 | occasionally useful if you want to provide your own wrapper functions |
4483 | around libev functions. |
4808 | around libev functions. |
… | |
… | |
4486 | If undefined or defined to \f(CW1\fR, then all event-loop-specific functions |
4811 | If undefined or defined to \f(CW1\fR, then all event-loop-specific functions |
4487 | will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create |
4812 | will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create |
4488 | additional independent event loops. Otherwise there will be no support |
4813 | additional independent event loops. Otherwise there will be no support |
4489 | for multiple event loops and there is no first event loop pointer |
4814 | for multiple event loops and there is no first event loop pointer |
4490 | argument. Instead, all functions act on the single default loop. |
4815 | argument. Instead, all functions act on the single default loop. |
|
|
4816 | .Sp |
|
|
4817 | Note that \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR will no longer provide a |
|
|
4818 | default loop when multiplicity is switched off \- you always have to |
|
|
4819 | initialise the loop manually in this case. |
4491 | .IP "\s-1EV_MINPRI\s0" 4 |
4820 | .IP "\s-1EV_MINPRI\s0" 4 |
4492 | .IX Item "EV_MINPRI" |
4821 | .IX Item "EV_MINPRI" |
4493 | .PD 0 |
4822 | .PD 0 |
4494 | .IP "\s-1EV_MAXPRI\s0" 4 |
4823 | .IP "\s-1EV_MAXPRI\s0" 4 |
4495 | .IX Item "EV_MAXPRI" |
4824 | .IX Item "EV_MAXPRI" |
… | |
… | |
4503 | all the priorities, so having many of them (hundreds) uses a lot of space |
4832 | all the priorities, so having many of them (hundreds) uses a lot of space |
4504 | and time, so using the defaults of five priorities (\-2 .. +2) is usually |
4833 | and time, so using the defaults of five priorities (\-2 .. +2) is usually |
4505 | fine. |
4834 | fine. |
4506 | .Sp |
4835 | .Sp |
4507 | If your embedding application does not need any priorities, defining these |
4836 | If your embedding application does not need any priorities, defining these |
4508 | both to \f(CW0\fR will save some memory and \s-1CPU\s0. |
4837 | both to \f(CW0\fR will save some memory and \s-1CPU.\s0 |
4509 | .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 |
4838 | .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 |
4510 | .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." |
4839 | .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." |
4511 | If undefined or defined to be \f(CW1\fR (and the platform supports it), then |
4840 | If undefined or defined to be \f(CW1\fR (and the platform supports it), then |
4512 | the respective watcher type is supported. If defined to be \f(CW0\fR, then it |
4841 | the respective watcher type is supported. If defined to be \f(CW0\fR, then it |
4513 | is not. Disabling watcher types mainly saves code size. |
4842 | is not. Disabling watcher types mainly saves code size. |
4514 | .IP "\s-1EV_FEATURES\s0" 4 |
4843 | .IP "\s-1EV_FEATURES\s0" 4 |
… | |
… | |
4531 | \& #define EV_CHILD_ENABLE 1 |
4860 | \& #define EV_CHILD_ENABLE 1 |
4532 | \& #define EV_ASYNC_ENABLE 1 |
4861 | \& #define EV_ASYNC_ENABLE 1 |
4533 | .Ve |
4862 | .Ve |
4534 | .Sp |
4863 | .Sp |
4535 | The actual value is a bitset, it can be a combination of the following |
4864 | The actual value is a bitset, it can be a combination of the following |
4536 | values: |
4865 | values (by default, all of these are enabled): |
4537 | .RS 4 |
4866 | .RS 4 |
4538 | .ie n .IP "1 \- faster/larger code" 4 |
4867 | .ie n .IP "1 \- faster/larger code" 4 |
4539 | .el .IP "\f(CW1\fR \- faster/larger code" 4 |
4868 | .el .IP "\f(CW1\fR \- faster/larger code" 4 |
4540 | .IX Item "1 - faster/larger code" |
4869 | .IX Item "1 - faster/larger code" |
4541 | Use larger code to speed up some operations. |
4870 | Use larger code to speed up some operations. |
… | |
… | |
4544 | code size by roughly 30% on amd64). |
4873 | code size by roughly 30% on amd64). |
4545 | .Sp |
4874 | .Sp |
4546 | When optimising for size, use of compiler flags such as \f(CW\*(C`\-Os\*(C'\fR with |
4875 | When optimising for size, use of compiler flags such as \f(CW\*(C`\-Os\*(C'\fR with |
4547 | gcc is recommended, as well as \f(CW\*(C`\-DNDEBUG\*(C'\fR, as libev contains a number of |
4876 | gcc is recommended, as well as \f(CW\*(C`\-DNDEBUG\*(C'\fR, as libev contains a number of |
4548 | assertions. |
4877 | assertions. |
|
|
4878 | .Sp |
|
|
4879 | The default is off when \f(CW\*(C`_\|_OPTIMIZE_SIZE_\|_\*(C'\fR is defined by your compiler |
|
|
4880 | (e.g. gcc with \f(CW\*(C`\-Os\*(C'\fR). |
4549 | .ie n .IP "2 \- faster/larger data structures" 4 |
4881 | .ie n .IP "2 \- faster/larger data structures" 4 |
4550 | .el .IP "\f(CW2\fR \- faster/larger data structures" 4 |
4882 | .el .IP "\f(CW2\fR \- faster/larger data structures" 4 |
4551 | .IX Item "2 - faster/larger data structures" |
4883 | .IX Item "2 - faster/larger data structures" |
4552 | Replaces the small 2\-heap for timer management by a faster 4\-heap, larger |
4884 | Replaces the small 2\-heap for timer management by a faster 4\-heap, larger |
4553 | hash table sizes and so on. This will usually further increase code size |
4885 | hash table sizes and so on. This will usually further increase code size |
4554 | and can additionally have an effect on the size of data structures at |
4886 | and can additionally have an effect on the size of data structures at |
4555 | runtime. |
4887 | runtime. |
|
|
4888 | .Sp |
|
|
4889 | The default is off when \f(CW\*(C`_\|_OPTIMIZE_SIZE_\|_\*(C'\fR is defined by your compiler |
|
|
4890 | (e.g. gcc with \f(CW\*(C`\-Os\*(C'\fR). |
4556 | .ie n .IP "4 \- full \s-1API\s0 configuration" 4 |
4891 | .ie n .IP "4 \- full \s-1API\s0 configuration" 4 |
4557 | .el .IP "\f(CW4\fR \- full \s-1API\s0 configuration" 4 |
4892 | .el .IP "\f(CW4\fR \- full \s-1API\s0 configuration" 4 |
4558 | .IX Item "4 - full API configuration" |
4893 | .IX Item "4 - full API configuration" |
4559 | This enables priorities (sets \f(CW\*(C`EV_MAXPRI\*(C'\fR=2 and \f(CW\*(C`EV_MINPRI\*(C'\fR=\-2), and |
4894 | This enables priorities (sets \f(CW\*(C`EV_MAXPRI\*(C'\fR=2 and \f(CW\*(C`EV_MINPRI\*(C'\fR=\-2), and |
4560 | enables multiplicity (\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR=1). |
4895 | enables multiplicity (\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR=1). |
… | |
… | |
4592 | With an intelligent-enough linker (gcc+binutils are intelligent enough |
4927 | With an intelligent-enough linker (gcc+binutils are intelligent enough |
4593 | when you use \f(CW\*(C`\-Wl,\-\-gc\-sections \-ffunction\-sections\*(C'\fR) functions unused by |
4928 | when you use \f(CW\*(C`\-Wl,\-\-gc\-sections \-ffunction\-sections\*(C'\fR) functions unused by |
4594 | your program might be left out as well \- a binary starting a timer and an |
4929 | your program might be left out as well \- a binary starting a timer and an |
4595 | I/O watcher then might come out at only 5Kb. |
4930 | I/O watcher then might come out at only 5Kb. |
4596 | .RE |
4931 | .RE |
|
|
4932 | .IP "\s-1EV_API_STATIC\s0" 4 |
|
|
4933 | .IX Item "EV_API_STATIC" |
|
|
4934 | If this symbol is defined (by default it is not), then all identifiers |
|
|
4935 | will have static linkage. This means that libev will not export any |
|
|
4936 | identifiers, and you cannot link against libev anymore. This can be useful |
|
|
4937 | when you embed libev, only want to use libev functions in a single file, |
|
|
4938 | and do not want its identifiers to be visible. |
|
|
4939 | .Sp |
|
|
4940 | To use this, define \f(CW\*(C`EV_API_STATIC\*(C'\fR and include \fIev.c\fR in the file that |
|
|
4941 | wants to use libev. |
|
|
4942 | .Sp |
|
|
4943 | This option only works when libev is compiled with a C compiler, as \*(C+ |
|
|
4944 | doesn't support the required declaration syntax. |
4597 | .IP "\s-1EV_AVOID_STDIO\s0" 4 |
4945 | .IP "\s-1EV_AVOID_STDIO\s0" 4 |
4598 | .IX Item "EV_AVOID_STDIO" |
4946 | .IX Item "EV_AVOID_STDIO" |
4599 | If this is set to \f(CW1\fR at compiletime, then libev will avoid using stdio |
4947 | If this is set to \f(CW1\fR at compiletime, then libev will avoid using stdio |
4600 | functions (printf, scanf, perror etc.). This will increase the code size |
4948 | functions (printf, scanf, perror etc.). This will increase the code size |
4601 | somewhat, but if your program doesn't otherwise depend on stdio and your |
4949 | somewhat, but if your program doesn't otherwise depend on stdio and your |
… | |
… | |
4669 | .Vb 3 |
5017 | .Vb 3 |
4670 | \& #define EV_COMMON \e |
5018 | \& #define EV_COMMON \e |
4671 | \& SV *self; /* contains this struct */ \e |
5019 | \& SV *self; /* contains this struct */ \e |
4672 | \& SV *cb_sv, *fh /* note no trailing ";" */ |
5020 | \& SV *cb_sv, *fh /* note no trailing ";" */ |
4673 | .Ve |
5021 | .Ve |
4674 | .IP "\s-1EV_CB_DECLARE\s0 (type)" 4 |
5022 | .IP "\s-1EV_CB_DECLARE \s0(type)" 4 |
4675 | .IX Item "EV_CB_DECLARE (type)" |
5023 | .IX Item "EV_CB_DECLARE (type)" |
4676 | .PD 0 |
5024 | .PD 0 |
4677 | .IP "\s-1EV_CB_INVOKE\s0 (watcher, revents)" 4 |
5025 | .IP "\s-1EV_CB_INVOKE \s0(watcher, revents)" 4 |
4678 | .IX Item "EV_CB_INVOKE (watcher, revents)" |
5026 | .IX Item "EV_CB_INVOKE (watcher, revents)" |
4679 | .IP "ev_set_cb (ev, cb)" 4 |
5027 | .IP "ev_set_cb (ev, cb)" 4 |
4680 | .IX Item "ev_set_cb (ev, cb)" |
5028 | .IX Item "ev_set_cb (ev, cb)" |
4681 | .PD |
5029 | .PD |
4682 | Can be used to change the callback member declaration in each watcher, |
5030 | Can be used to change the callback member declaration in each watcher, |
4683 | and the way callbacks are invoked and set. Must expand to a struct member |
5031 | and the way callbacks are invoked and set. Must expand to a struct member |
4684 | definition and a statement, respectively. See the \fIev.h\fR header file for |
5032 | definition and a statement, respectively. See the \fIev.h\fR header file for |
4685 | their default definitions. One possible use for overriding these is to |
5033 | their default definitions. One possible use for overriding these is to |
4686 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
5034 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
4687 | method calls instead of plain function calls in \*(C+. |
5035 | method calls instead of plain function calls in \*(C+. |
4688 | .SS "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0" |
5036 | .SS "\s-1EXPORTED API SYMBOLS\s0" |
4689 | .IX Subsection "EXPORTED API SYMBOLS" |
5037 | .IX Subsection "EXPORTED API SYMBOLS" |
4690 | If you need to re-export the \s-1API\s0 (e.g. via a \s-1DLL\s0) and you need a list of |
5038 | If you need to re-export the \s-1API \s0(e.g. via a \s-1DLL\s0) and you need a list of |
4691 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
5039 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
4692 | all public symbols, one per line: |
5040 | all public symbols, one per line: |
4693 | .PP |
5041 | .PP |
4694 | .Vb 2 |
5042 | .Vb 2 |
4695 | \& Symbols.ev for libev proper |
5043 | \& Symbols.ev for libev proper |
… | |
… | |
4747 | \& #include "ev_cpp.h" |
5095 | \& #include "ev_cpp.h" |
4748 | \& #include "ev.c" |
5096 | \& #include "ev.c" |
4749 | .Ve |
5097 | .Ve |
4750 | .SH "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT" |
5098 | .SH "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT" |
4751 | .IX Header "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT" |
5099 | .IX Header "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT" |
4752 | .SS "\s-1THREADS\s0 \s-1AND\s0 \s-1COROUTINES\s0" |
5100 | .SS "\s-1THREADS AND COROUTINES\s0" |
4753 | .IX Subsection "THREADS AND COROUTINES" |
5101 | .IX Subsection "THREADS AND COROUTINES" |
4754 | \fI\s-1THREADS\s0\fR |
5102 | \fI\s-1THREADS\s0\fR |
4755 | .IX Subsection "THREADS" |
5103 | .IX Subsection "THREADS" |
4756 | .PP |
5104 | .PP |
4757 | All libev functions are reentrant and thread-safe unless explicitly |
5105 | All libev functions are reentrant and thread-safe unless explicitly |
… | |
… | |
4803 | An example use would be to communicate signals or other events that only |
5151 | An example use would be to communicate signals or other events that only |
4804 | work in the default loop by registering the signal watcher with the |
5152 | work in the default loop by registering the signal watcher with the |
4805 | default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop |
5153 | default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop |
4806 | watcher callback into the event loop interested in the signal. |
5154 | watcher callback into the event loop interested in the signal. |
4807 | .PP |
5155 | .PP |
4808 | See also \*(L"\s-1THREAD\s0 \s-1LOCKING\s0 \s-1EXAMPLE\s0\*(R". |
5156 | See also \*(L"\s-1THREAD LOCKING EXAMPLE\*(R"\s0. |
4809 | .PP |
5157 | .PP |
4810 | \fI\s-1COROUTINES\s0\fR |
5158 | \fI\s-1COROUTINES\s0\fR |
4811 | .IX Subsection "COROUTINES" |
5159 | .IX Subsection "COROUTINES" |
4812 | .PP |
5160 | .PP |
4813 | Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"): |
5161 | Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"): |
… | |
… | |
4818 | that you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. |
5166 | that you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. |
4819 | .PP |
5167 | .PP |
4820 | Care has been taken to ensure that libev does not keep local state inside |
5168 | Care has been taken to ensure that libev does not keep local state inside |
4821 | \&\f(CW\*(C`ev_run\*(C'\fR, and other calls do not usually allow for coroutine switches as |
5169 | \&\f(CW\*(C`ev_run\*(C'\fR, and other calls do not usually allow for coroutine switches as |
4822 | they do not call any callbacks. |
5170 | they do not call any callbacks. |
4823 | .SS "\s-1COMPILER\s0 \s-1WARNINGS\s0" |
5171 | .SS "\s-1COMPILER WARNINGS\s0" |
4824 | .IX Subsection "COMPILER WARNINGS" |
5172 | .IX Subsection "COMPILER WARNINGS" |
4825 | Depending on your compiler and compiler settings, you might get no or a |
5173 | Depending on your compiler and compiler settings, you might get no or a |
4826 | lot of warnings when compiling libev code. Some people are apparently |
5174 | lot of warnings when compiling libev code. Some people are apparently |
4827 | scared by this. |
5175 | scared by this. |
4828 | .PP |
5176 | .PP |
… | |
… | |
4880 | .PP |
5228 | .PP |
4881 | If you need, for some reason, empty reports from valgrind for your project |
5229 | If you need, for some reason, empty reports from valgrind for your project |
4882 | I suggest using suppression lists. |
5230 | I suggest using suppression lists. |
4883 | .SH "PORTABILITY NOTES" |
5231 | .SH "PORTABILITY NOTES" |
4884 | .IX Header "PORTABILITY NOTES" |
5232 | .IX Header "PORTABILITY NOTES" |
4885 | .SS "\s-1GNU/LINUX\s0 32 \s-1BIT\s0 \s-1LIMITATIONS\s0" |
5233 | .SS "\s-1GNU/LINUX 32 BIT LIMITATIONS\s0" |
4886 | .IX Subsection "GNU/LINUX 32 BIT LIMITATIONS" |
5234 | .IX Subsection "GNU/LINUX 32 BIT LIMITATIONS" |
4887 | GNU/Linux is the only common platform that supports 64 bit file/large file |
5235 | GNU/Linux is the only common platform that supports 64 bit file/large file |
4888 | interfaces but \fIdisables\fR them by default. |
5236 | interfaces but \fIdisables\fR them by default. |
4889 | .PP |
5237 | .PP |
4890 | That means that libev compiled in the default environment doesn't support |
5238 | That means that libev compiled in the default environment doesn't support |
4891 | files larger than 2GiB or so, which mainly affects \f(CW\*(C`ev_stat\*(C'\fR watchers. |
5239 | files larger than 2GiB or so, which mainly affects \f(CW\*(C`ev_stat\*(C'\fR watchers. |
4892 | .PP |
5240 | .PP |
4893 | Unfortunately, many programs try to work around this GNU/Linux issue |
5241 | Unfortunately, many programs try to work around this GNU/Linux issue |
4894 | by enabling the large file \s-1API\s0, which makes them incompatible with the |
5242 | by enabling the large file \s-1API,\s0 which makes them incompatible with the |
4895 | standard libev compiled for their system. |
5243 | standard libev compiled for their system. |
4896 | .PP |
5244 | .PP |
4897 | Likewise, libev cannot enable the large file \s-1API\s0 itself as this would |
5245 | Likewise, libev cannot enable the large file \s-1API\s0 itself as this would |
4898 | suddenly make it incompatible to the default compile time environment, |
5246 | suddenly make it incompatible to the default compile time environment, |
4899 | i.e. all programs not using special compile switches. |
5247 | i.e. all programs not using special compile switches. |
4900 | .SS "\s-1OS/X\s0 \s-1AND\s0 \s-1DARWIN\s0 \s-1BUGS\s0" |
5248 | .SS "\s-1OS/X AND DARWIN BUGS\s0" |
4901 | .IX Subsection "OS/X AND DARWIN BUGS" |
5249 | .IX Subsection "OS/X AND DARWIN BUGS" |
4902 | The whole thing is a bug if you ask me \- basically any system interface |
5250 | The whole thing is a bug if you ask me \- basically any system interface |
4903 | you touch is broken, whether it is locales, poll, kqueue or even the |
5251 | you touch is broken, whether it is locales, poll, kqueue or even the |
4904 | OpenGL drivers. |
5252 | OpenGL drivers. |
4905 | .PP |
5253 | .PP |
… | |
… | |
4927 | .PP |
5275 | .PP |
4928 | \fI\f(CI\*(C`select\*(C'\fI is buggy\fR |
5276 | \fI\f(CI\*(C`select\*(C'\fI is buggy\fR |
4929 | .IX Subsection "select is buggy" |
5277 | .IX Subsection "select is buggy" |
4930 | .PP |
5278 | .PP |
4931 | All that's left is \f(CW\*(C`select\*(C'\fR, and of course Apple found a way to fuck this |
5279 | All that's left is \f(CW\*(C`select\*(C'\fR, and of course Apple found a way to fuck this |
4932 | one up as well: On \s-1OS/X\s0, \f(CW\*(C`select\*(C'\fR actively limits the number of file |
5280 | one up as well: On \s-1OS/X, \s0\f(CW\*(C`select\*(C'\fR actively limits the number of file |
4933 | descriptors you can pass in to 1024 \- your program suddenly crashes when |
5281 | descriptors you can pass in to 1024 \- your program suddenly crashes when |
4934 | you use more. |
5282 | you use more. |
4935 | .PP |
5283 | .PP |
4936 | There is an undocumented \*(L"workaround\*(R" for this \- defining |
5284 | There is an undocumented \*(L"workaround\*(R" for this \- defining |
4937 | \&\f(CW\*(C`_DARWIN_UNLIMITED_SELECT\*(C'\fR, which libev tries to use, so select \fIshould\fR |
5285 | \&\f(CW\*(C`_DARWIN_UNLIMITED_SELECT\*(C'\fR, which libev tries to use, so select \fIshould\fR |
4938 | work on \s-1OS/X\s0. |
5286 | work on \s-1OS/X.\s0 |
4939 | .SS "\s-1SOLARIS\s0 \s-1PROBLEMS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" |
5287 | .SS "\s-1SOLARIS PROBLEMS AND WORKAROUNDS\s0" |
4940 | .IX Subsection "SOLARIS PROBLEMS AND WORKAROUNDS" |
5288 | .IX Subsection "SOLARIS PROBLEMS AND WORKAROUNDS" |
4941 | \fI\f(CI\*(C`errno\*(C'\fI reentrancy\fR |
5289 | \fI\f(CI\*(C`errno\*(C'\fI reentrancy\fR |
4942 | .IX Subsection "errno reentrancy" |
5290 | .IX Subsection "errno reentrancy" |
4943 | .PP |
5291 | .PP |
4944 | The default compile environment on Solaris is unfortunately so |
5292 | The default compile environment on Solaris is unfortunately so |
… | |
… | |
4961 | great. |
5309 | great. |
4962 | .PP |
5310 | .PP |
4963 | If you can't get it to work, you can try running the program by setting |
5311 | If you can't get it to work, you can try running the program by setting |
4964 | the environment variable \f(CW\*(C`LIBEV_FLAGS=3\*(C'\fR to only allow \f(CW\*(C`poll\*(C'\fR and |
5312 | the environment variable \f(CW\*(C`LIBEV_FLAGS=3\*(C'\fR to only allow \f(CW\*(C`poll\*(C'\fR and |
4965 | \&\f(CW\*(C`select\*(C'\fR backends. |
5313 | \&\f(CW\*(C`select\*(C'\fR backends. |
4966 | .SS "\s-1AIX\s0 \s-1POLL\s0 \s-1BUG\s0" |
5314 | .SS "\s-1AIX POLL BUG\s0" |
4967 | .IX Subsection "AIX POLL BUG" |
5315 | .IX Subsection "AIX POLL BUG" |
4968 | \&\s-1AIX\s0 unfortunately has a broken \f(CW\*(C`poll.h\*(C'\fR header. Libev works around |
5316 | \&\s-1AIX\s0 unfortunately has a broken \f(CW\*(C`poll.h\*(C'\fR header. Libev works around |
4969 | this by trying to avoid the poll backend altogether (i.e. it's not even |
5317 | this by trying to avoid the poll backend altogether (i.e. it's not even |
4970 | compiled in), which normally isn't a big problem as \f(CW\*(C`select\*(C'\fR works fine |
5318 | compiled in), which normally isn't a big problem as \f(CW\*(C`select\*(C'\fR works fine |
4971 | with large bitsets on \s-1AIX\s0, and \s-1AIX\s0 is dead anyway. |
5319 | with large bitsets on \s-1AIX,\s0 and \s-1AIX\s0 is dead anyway. |
4972 | .SS "\s-1WIN32\s0 \s-1PLATFORM\s0 \s-1LIMITATIONS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" |
5320 | .SS "\s-1WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS\s0" |
4973 | .IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS" |
5321 | .IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS" |
4974 | \fIGeneral issues\fR |
5322 | \fIGeneral issues\fR |
4975 | .IX Subsection "General issues" |
5323 | .IX Subsection "General issues" |
4976 | .PP |
5324 | .PP |
4977 | Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev |
5325 | Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev |
4978 | requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 |
5326 | requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 |
4979 | model. Libev still offers limited functionality on this platform in |
5327 | model. Libev still offers limited functionality on this platform in |
4980 | the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket |
5328 | the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket |
4981 | descriptors. This only applies when using Win32 natively, not when using |
5329 | descriptors. This only applies when using Win32 natively, not when using |
4982 | e.g. cygwin. Actually, it only applies to the microsofts own compilers, |
5330 | e.g. cygwin. Actually, it only applies to the microsofts own compilers, |
4983 | as every compielr comes with a slightly differently broken/incompatible |
5331 | as every compiler comes with a slightly differently broken/incompatible |
4984 | environment. |
5332 | environment. |
4985 | .PP |
5333 | .PP |
4986 | Lifting these limitations would basically require the full |
5334 | Lifting these limitations would basically require the full |
4987 | re-implementation of the I/O system. If you are into this kind of thing, |
5335 | re-implementation of the I/O system. If you are into this kind of thing, |
4988 | then note that glib does exactly that for you in a very portable way (note |
5336 | then note that glib does exactly that for you in a very portable way (note |
… | |
… | |
5046 | \& #define EV_USE_SELECT 1 |
5394 | \& #define EV_USE_SELECT 1 |
5047 | \& #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
5395 | \& #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
5048 | .Ve |
5396 | .Ve |
5049 | .PP |
5397 | .PP |
5050 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
5398 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
5051 | complexity in the O(nA\*^X) range when using win32. |
5399 | complexity in the O(nX) range when using win32. |
5052 | .PP |
5400 | .PP |
5053 | \fILimited number of file descriptors\fR |
5401 | \fILimited number of file descriptors\fR |
5054 | .IX Subsection "Limited number of file descriptors" |
5402 | .IX Subsection "Limited number of file descriptors" |
5055 | .PP |
5403 | .PP |
5056 | Windows has numerous arbitrary (and low) limits on things. |
5404 | Windows has numerous arbitrary (and low) limits on things. |
… | |
… | |
5072 | by calling \f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR |
5420 | by calling \f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR |
5073 | (another arbitrary limit), but is broken in many versions of the Microsoft |
5421 | (another arbitrary limit), but is broken in many versions of the Microsoft |
5074 | runtime libraries. This might get you to about \f(CW512\fR or \f(CW2048\fR sockets |
5422 | runtime libraries. This might get you to about \f(CW512\fR or \f(CW2048\fR sockets |
5075 | (depending on windows version and/or the phase of the moon). To get more, |
5423 | (depending on windows version and/or the phase of the moon). To get more, |
5076 | you need to wrap all I/O functions and provide your own fd management, but |
5424 | you need to wrap all I/O functions and provide your own fd management, but |
5077 | the cost of calling select (O(nA\*^X)) will likely make this unworkable. |
5425 | the cost of calling select (O(nX)) will likely make this unworkable. |
5078 | .SS "\s-1PORTABILITY\s0 \s-1REQUIREMENTS\s0" |
5426 | .SS "\s-1PORTABILITY REQUIREMENTS\s0" |
5079 | .IX Subsection "PORTABILITY REQUIREMENTS" |
5427 | .IX Subsection "PORTABILITY REQUIREMENTS" |
5080 | In addition to a working ISO-C implementation and of course the |
5428 | In addition to a working ISO-C implementation and of course the |
5081 | backend-specific APIs, libev relies on a few additional extensions: |
5429 | backend-specific APIs, libev relies on a few additional extensions: |
5082 | .ie n .IP """void (*)(ev_watcher_type *, int revents)"" must have compatible calling conventions regardless of ""ev_watcher_type *""." 4 |
5430 | .ie n .IP """void (*)(ev_watcher_type *, int revents)"" must have compatible calling conventions regardless of ""ev_watcher_type *""." 4 |
5083 | .el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4 |
5431 | .el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4 |
5084 | .IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *." |
5432 | .IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *." |
5085 | Libev assumes not only that all watcher pointers have the same internal |
5433 | Libev assumes not only that all watcher pointers have the same internal |
5086 | structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO\s0 C for example), but it also |
5434 | structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO C\s0 for example), but it also |
5087 | assumes that the same (machine) code can be used to call any watcher |
5435 | assumes that the same (machine) code can be used to call any watcher |
5088 | callback: The watcher callbacks have different type signatures, but libev |
5436 | callback: The watcher callbacks have different type signatures, but libev |
5089 | calls them using an \f(CW\*(C`ev_watcher *\*(C'\fR internally. |
5437 | calls them using an \f(CW\*(C`ev_watcher *\*(C'\fR internally. |
|
|
5438 | .IP "null pointers and integer zero are represented by 0 bytes" 4 |
|
|
5439 | .IX Item "null pointers and integer zero are represented by 0 bytes" |
|
|
5440 | Libev uses \f(CW\*(C`memset\*(C'\fR to initialise structs and arrays to \f(CW0\fR bytes, and |
|
|
5441 | relies on this setting pointers and integers to null. |
5090 | .IP "pointer accesses must be thread-atomic" 4 |
5442 | .IP "pointer accesses must be thread-atomic" 4 |
5091 | .IX Item "pointer accesses must be thread-atomic" |
5443 | .IX Item "pointer accesses must be thread-atomic" |
5092 | Accessing a pointer value must be atomic, it must both be readable and |
5444 | Accessing a pointer value must be atomic, it must both be readable and |
5093 | writable in one piece \- this is the case on all current architectures. |
5445 | writable in one piece \- this is the case on all current architectures. |
5094 | .ie n .IP """sig_atomic_t volatile"" must be thread-atomic as well" 4 |
5446 | .ie n .IP """sig_atomic_t volatile"" must be thread-atomic as well" 4 |
… | |
… | |
5107 | thread\*(R" or will block signals process-wide, both behaviours would |
5459 | thread\*(R" or will block signals process-wide, both behaviours would |
5108 | be compatible with libev. Interaction between \f(CW\*(C`sigprocmask\*(C'\fR and |
5460 | be compatible with libev. Interaction between \f(CW\*(C`sigprocmask\*(C'\fR and |
5109 | \&\f(CW\*(C`pthread_sigmask\*(C'\fR could complicate things, however. |
5461 | \&\f(CW\*(C`pthread_sigmask\*(C'\fR could complicate things, however. |
5110 | .Sp |
5462 | .Sp |
5111 | The most portable way to handle signals is to block signals in all threads |
5463 | The most portable way to handle signals is to block signals in all threads |
5112 | except the initial one, and run the default loop in the initial thread as |
5464 | except the initial one, and run the signal handling loop in the initial |
5113 | well. |
5465 | thread as well. |
5114 | .ie n .IP """long"" must be large enough for common memory allocation sizes" 4 |
5466 | .ie n .IP """long"" must be large enough for common memory allocation sizes" 4 |
5115 | .el .IP "\f(CWlong\fR must be large enough for common memory allocation sizes" 4 |
5467 | .el .IP "\f(CWlong\fR must be large enough for common memory allocation sizes" 4 |
5116 | .IX Item "long must be large enough for common memory allocation sizes" |
5468 | .IX Item "long must be large enough for common memory allocation sizes" |
5117 | To improve portability and simplify its \s-1API\s0, libev uses \f(CW\*(C`long\*(C'\fR internally |
5469 | To improve portability and simplify its \s-1API,\s0 libev uses \f(CW\*(C`long\*(C'\fR internally |
5118 | instead of \f(CW\*(C`size_t\*(C'\fR when allocating its data structures. On non-POSIX |
5470 | instead of \f(CW\*(C`size_t\*(C'\fR when allocating its data structures. On non-POSIX |
5119 | systems (Microsoft...) this might be unexpectedly low, but is still at |
5471 | systems (Microsoft...) this might be unexpectedly low, but is still at |
5120 | least 31 bits everywhere, which is enough for hundreds of millions of |
5472 | least 31 bits everywhere, which is enough for hundreds of millions of |
5121 | watchers. |
5473 | watchers. |
5122 | .ie n .IP """double"" must hold a time value in seconds with enough accuracy" 4 |
5474 | .ie n .IP """double"" must hold a time value in seconds with enough accuracy" 4 |
… | |
… | |
5124 | .IX Item "double must hold a time value in seconds with enough accuracy" |
5476 | .IX Item "double must hold a time value in seconds with enough accuracy" |
5125 | The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to |
5477 | The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to |
5126 | have at least 51 bits of mantissa (and 9 bits of exponent), which is |
5478 | have at least 51 bits of mantissa (and 9 bits of exponent), which is |
5127 | good enough for at least into the year 4000 with millisecond accuracy |
5479 | good enough for at least into the year 4000 with millisecond accuracy |
5128 | (the design goal for libev). This requirement is overfulfilled by |
5480 | (the design goal for libev). This requirement is overfulfilled by |
5129 | implementations using \s-1IEEE\s0 754, which is basically all existing ones. With |
5481 | implementations using \s-1IEEE 754,\s0 which is basically all existing ones. |
|
|
5482 | .Sp |
5130 | \&\s-1IEEE\s0 754 doubles, you get microsecond accuracy until at least 2200. |
5483 | With \s-1IEEE 754\s0 doubles, you get microsecond accuracy until at least the |
|
|
5484 | year 2255 (and millisecond accuracy till the year 287396 \- by then, libev |
|
|
5485 | is either obsolete or somebody patched it to use \f(CW\*(C`long double\*(C'\fR or |
|
|
5486 | something like that, just kidding). |
5131 | .PP |
5487 | .PP |
5132 | If you know of other additional requirements drop me a note. |
5488 | If you know of other additional requirements drop me a note. |
5133 | .SH "ALGORITHMIC COMPLEXITIES" |
5489 | .SH "ALGORITHMIC COMPLEXITIES" |
5134 | .IX Header "ALGORITHMIC COMPLEXITIES" |
5490 | .IX Header "ALGORITHMIC COMPLEXITIES" |
5135 | In this section the complexities of (many of) the algorithms used inside |
5491 | In this section the complexities of (many of) the algorithms used inside |
… | |
… | |
5189 | .IX Item "Processing ev_async_send: O(number_of_async_watchers)" |
5545 | .IX Item "Processing ev_async_send: O(number_of_async_watchers)" |
5190 | .IP "Processing signals: O(max_signal_number)" 4 |
5546 | .IP "Processing signals: O(max_signal_number)" 4 |
5191 | .IX Item "Processing signals: O(max_signal_number)" |
5547 | .IX Item "Processing signals: O(max_signal_number)" |
5192 | .PD |
5548 | .PD |
5193 | Sending involves a system call \fIiff\fR there were no other \f(CW\*(C`ev_async_send\*(C'\fR |
5549 | Sending involves a system call \fIiff\fR there were no other \f(CW\*(C`ev_async_send\*(C'\fR |
5194 | calls in the current loop iteration. Checking for async and signal events |
5550 | calls in the current loop iteration and the loop is currently |
|
|
5551 | blocked. Checking for async and signal events involves iterating over all |
5195 | involves iterating over all running async watchers or all signal numbers. |
5552 | running async watchers or all signal numbers. |
5196 | .SH "PORTING FROM LIBEV 3.X TO 4.X" |
5553 | .SH "PORTING FROM LIBEV 3.X TO 4.X" |
5197 | .IX Header "PORTING FROM LIBEV 3.X TO 4.X" |
5554 | .IX Header "PORTING FROM LIBEV 3.X TO 4.X" |
5198 | The major version 4 introduced some incompatible changes to the \s-1API\s0. |
5555 | The major version 4 introduced some incompatible changes to the \s-1API.\s0 |
5199 | .PP |
5556 | .PP |
5200 | At the moment, the \f(CW\*(C`ev.h\*(C'\fR header file provides compatibility definitions |
5557 | At the moment, the \f(CW\*(C`ev.h\*(C'\fR header file provides compatibility definitions |
5201 | for all changes, so most programs should still compile. The compatibility |
5558 | for all changes, so most programs should still compile. The compatibility |
5202 | layer might be removed in later versions of libev, so better update to the |
5559 | layer might be removed in later versions of libev, so better update to the |
5203 | new \s-1API\s0 early than late. |
5560 | new \s-1API\s0 early than late. |
5204 | .ie n .IP """EV_COMPAT3"" backwards compatibility mechanism" 4 |
5561 | .ie n .IP """EV_COMPAT3"" backwards compatibility mechanism" 4 |
5205 | .el .IP "\f(CWEV_COMPAT3\fR backwards compatibility mechanism" 4 |
5562 | .el .IP "\f(CWEV_COMPAT3\fR backwards compatibility mechanism" 4 |
5206 | .IX Item "EV_COMPAT3 backwards compatibility mechanism" |
5563 | .IX Item "EV_COMPAT3 backwards compatibility mechanism" |
5207 | The backward compatibility mechanism can be controlled by |
5564 | The backward compatibility mechanism can be controlled by |
5208 | \&\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 |
5565 | \&\f(CW\*(C`EV_COMPAT3\*(C'\fR. See \*(L"\s-1PREPROCESSOR SYMBOLS/MACROS\*(R"\s0 in the \*(L"\s-1EMBEDDING\*(R"\s0 |
5209 | section. |
5566 | section. |
5210 | .ie n .IP """ev_default_destroy"" and ""ev_default_fork"" have been removed" 4 |
5567 | .ie n .IP """ev_default_destroy"" and ""ev_default_fork"" have been removed" 4 |
5211 | .el .IP "\f(CWev_default_destroy\fR and \f(CWev_default_fork\fR have been removed" 4 |
5568 | .el .IP "\f(CWev_default_destroy\fR and \f(CWev_default_fork\fR have been removed" 4 |
5212 | .IX Item "ev_default_destroy and ev_default_fork have been removed" |
5569 | .IX Item "ev_default_destroy and ev_default_fork have been removed" |
5213 | These calls can be replaced easily by their \f(CW\*(C`ev_loop_xxx\*(C'\fR counterparts: |
5570 | These calls can be replaced easily by their \f(CW\*(C`ev_loop_xxx\*(C'\fR counterparts: |
… | |
… | |
5253 | .SH "GLOSSARY" |
5610 | .SH "GLOSSARY" |
5254 | .IX Header "GLOSSARY" |
5611 | .IX Header "GLOSSARY" |
5255 | .IP "active" 4 |
5612 | .IP "active" 4 |
5256 | .IX Item "active" |
5613 | .IX Item "active" |
5257 | A watcher is active as long as it has been started and not yet stopped. |
5614 | A watcher is active as long as it has been started and not yet stopped. |
5258 | See \*(L"\s-1WATCHER\s0 \s-1STATES\s0\*(R" for details. |
5615 | See \*(L"\s-1WATCHER STATES\*(R"\s0 for details. |
5259 | .IP "application" 4 |
5616 | .IP "application" 4 |
5260 | .IX Item "application" |
5617 | .IX Item "application" |
5261 | In this document, an application is whatever is using libev. |
5618 | In this document, an application is whatever is using libev. |
5262 | .IP "backend" 4 |
5619 | .IP "backend" 4 |
5263 | .IX Item "backend" |
5620 | .IX Item "backend" |
… | |
… | |
5290 | The model used to describe how an event loop handles and processes |
5647 | The model used to describe how an event loop handles and processes |
5291 | watchers and events. |
5648 | watchers and events. |
5292 | .IP "pending" 4 |
5649 | .IP "pending" 4 |
5293 | .IX Item "pending" |
5650 | .IX Item "pending" |
5294 | A watcher is pending as soon as the corresponding event has been |
5651 | A watcher is pending as soon as the corresponding event has been |
5295 | detected. See \*(L"\s-1WATCHER\s0 \s-1STATES\s0\*(R" for details. |
5652 | detected. See \*(L"\s-1WATCHER STATES\*(R"\s0 for details. |
5296 | .IP "real time" 4 |
5653 | .IP "real time" 4 |
5297 | .IX Item "real time" |
5654 | .IX Item "real time" |
5298 | The physical time that is observed. It is apparently strictly monotonic :) |
5655 | The physical time that is observed. It is apparently strictly monotonic :) |
5299 | .IP "wall-clock time" 4 |
5656 | .IP "wall-clock time" 4 |
5300 | .IX Item "wall-clock time" |
5657 | .IX Item "wall-clock time" |