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126 | .IX Title "LIBEV 3" |
135 | .IX Title "LIBEV 3" |
127 | .TH LIBEV 3 "2013-02-28" "libev-4.11" "libev - high performance full featured event loop" |
136 | .TH LIBEV 3 "2019-07-07" "libev-4.27" "libev - high performance full featured event loop" |
128 | .\" For nroff, turn off justification. Always turn off hyphenation; it makes |
137 | .\" For nroff, turn off justification. Always turn off hyphenation; it makes |
129 | .\" way too many mistakes in technical documents. |
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130 | .if n .ad l |
139 | .if n .ad l |
131 | .nh |
140 | .nh |
132 | .SH "NAME" |
141 | .SH "NAME" |
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134 | .SH "SYNOPSIS" |
143 | .SH "SYNOPSIS" |
135 | .IX Header "SYNOPSIS" |
144 | .IX Header "SYNOPSIS" |
136 | .Vb 1 |
145 | .Vb 1 |
137 | \& #include <ev.h> |
146 | \& #include <ev.h> |
138 | .Ve |
147 | .Ve |
139 | .SS "\s-1EXAMPLE\s0 \s-1PROGRAM\s0" |
148 | .SS "\s-1EXAMPLE PROGRAM\s0" |
140 | .IX Subsection "EXAMPLE PROGRAM" |
149 | .IX Subsection "EXAMPLE PROGRAM" |
141 | .Vb 2 |
150 | .Vb 2 |
142 | \& // a single header file is required |
151 | \& // a single header file is required |
143 | \& #include <ev.h> |
152 | \& #include <ev.h> |
144 | \& |
153 | \& |
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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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231 | watchers\fR, which are relatively small C structures you initialise with the |
240 | watchers\fR, which are relatively small C structures you initialise with the |
232 | details of the event, and then hand it over to libev by \fIstarting\fR the |
241 | details of the event, and then hand it over to libev by \fIstarting\fR the |
233 | watcher. |
242 | watcher. |
234 | .SS "\s-1FEATURES\s0" |
243 | .SS "\s-1FEATURES\s0" |
235 | .IX Subsection "FEATURES" |
244 | .IX Subsection "FEATURES" |
236 | Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the Linux-specific \f(CW\*(C`epoll\*(C'\fR, the |
245 | Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the Linux-specific aio and \f(CW\*(C`epoll\*(C'\fR |
237 | BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port mechanisms |
246 | interfaces, the BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port |
238 | for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR interface |
247 | mechanisms for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR |
239 | (for \f(CW\*(C`ev_stat\*(C'\fR), Linux eventfd/signalfd (for faster and cleaner |
248 | interface (for \f(CW\*(C`ev_stat\*(C'\fR), Linux eventfd/signalfd (for faster and cleaner |
240 | inter-thread wakeup (\f(CW\*(C`ev_async\*(C'\fR)/signal handling (\f(CW\*(C`ev_signal\*(C'\fR)) relative |
249 | inter-thread wakeup (\f(CW\*(C`ev_async\*(C'\fR)/signal handling (\f(CW\*(C`ev_signal\*(C'\fR)) relative |
241 | timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers with customised rescheduling |
250 | timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers with customised rescheduling |
242 | (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals (\f(CW\*(C`ev_signal\*(C'\fR), process status |
251 | (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals (\f(CW\*(C`ev_signal\*(C'\fR), process status |
243 | change events (\f(CW\*(C`ev_child\*(C'\fR), and event watchers dealing with the event |
252 | change events (\f(CW\*(C`ev_child\*(C'\fR), and event watchers dealing with the event |
244 | loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR, \f(CW\*(C`ev_embed\*(C'\fR, \f(CW\*(C`ev_prepare\*(C'\fR and |
253 | loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR, \f(CW\*(C`ev_embed\*(C'\fR, \f(CW\*(C`ev_prepare\*(C'\fR and |
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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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282 | When libev detects a usage error such as a negative timer interval, then |
291 | When libev detects a usage error such as a negative timer interval, then |
283 | it will print a diagnostic message and abort (via the \f(CW\*(C`assert\*(C'\fR mechanism, |
292 | it will print a diagnostic message and abort (via the \f(CW\*(C`assert\*(C'\fR mechanism, |
284 | so \f(CW\*(C`NDEBUG\*(C'\fR will disable this checking): these are programming errors in |
293 | so \f(CW\*(C`NDEBUG\*(C'\fR will disable this checking): these are programming errors in |
285 | the libev caller and need to be fixed there. |
294 | the libev caller and need to be fixed there. |
286 | .PP |
295 | .PP |
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296 | Via the \f(CW\*(C`EV_FREQUENT\*(C'\fR macro you can compile in and/or enable extensive |
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297 | consistency checking code inside libev that can be used to check for |
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298 | internal inconsistencies, suually caused by application bugs. |
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299 | .PP |
287 | Libev also has a few internal error-checking \f(CW\*(C`assert\*(C'\fRions, and also has |
300 | Libev also has a few internal error-checking \f(CW\*(C`assert\*(C'\fRions. These do not |
288 | extensive consistency checking code. These do not trigger under normal |
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289 | circumstances, as they indicate either a bug in libev or worse. |
301 | trigger under normal circumstances, as they indicate either a bug in libev |
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302 | or worse. |
290 | .SH "GLOBAL FUNCTIONS" |
303 | .SH "GLOBAL FUNCTIONS" |
291 | .IX Header "GLOBAL FUNCTIONS" |
304 | .IX Header "GLOBAL FUNCTIONS" |
292 | These functions can be called anytime, even before initialising the |
305 | These functions can be called anytime, even before initialising the |
293 | library in any way. |
306 | library in any way. |
294 | .IP "ev_tstamp ev_time ()" 4 |
307 | .IP "ev_tstamp ev_time ()" 4 |
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383 | .Sp |
396 | .Sp |
384 | You could override this function in high-availability programs to, say, |
397 | You could override this function in high-availability programs to, say, |
385 | free some memory if it cannot allocate memory, to use a special allocator, |
398 | free some memory if it cannot allocate memory, to use a special allocator, |
386 | or even to sleep a while and retry until some memory is available. |
399 | or even to sleep a while and retry until some memory is available. |
387 | .Sp |
400 | .Sp |
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401 | Example: The following is the \f(CW\*(C`realloc\*(C'\fR function that libev itself uses |
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402 | which should work with \f(CW\*(C`realloc\*(C'\fR and \f(CW\*(C`free\*(C'\fR functions of all kinds and |
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403 | is probably a good basis for your own implementation. |
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404 | .Sp |
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405 | .Vb 5 |
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406 | \& static void * |
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407 | \& ev_realloc_emul (void *ptr, long size) EV_NOEXCEPT |
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408 | \& { |
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409 | \& if (size) |
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410 | \& return realloc (ptr, size); |
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411 | \& |
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412 | \& free (ptr); |
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413 | \& return 0; |
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414 | \& } |
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415 | .Ve |
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416 | .Sp |
388 | Example: Replace the libev allocator with one that waits a bit and then |
417 | Example: Replace the libev allocator with one that waits a bit and then |
389 | retries (example requires a standards-compliant \f(CW\*(C`realloc\*(C'\fR). |
418 | retries. |
390 | .Sp |
419 | .Sp |
391 | .Vb 6 |
420 | .Vb 8 |
392 | \& static void * |
421 | \& static void * |
393 | \& persistent_realloc (void *ptr, size_t size) |
422 | \& persistent_realloc (void *ptr, size_t size) |
394 | \& { |
423 | \& { |
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424 | \& if (!size) |
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425 | \& { |
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426 | \& free (ptr); |
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427 | \& return 0; |
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428 | \& } |
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429 | \& |
395 | \& for (;;) |
430 | \& for (;;) |
396 | \& { |
431 | \& { |
397 | \& void *newptr = realloc (ptr, size); |
432 | \& void *newptr = realloc (ptr, size); |
398 | \& |
433 | \& |
399 | \& if (newptr) |
434 | \& if (newptr) |
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514 | .IX Item "EVFLAG_NOENV" |
549 | .IX Item "EVFLAG_NOENV" |
515 | If this flag bit is or'ed into the flag value (or the program runs setuid |
550 | If this flag bit is or'ed into the flag value (or the program runs setuid |
516 | or setgid) then libev will \fInot\fR look at the environment variable |
551 | or setgid) then libev will \fInot\fR look at the environment variable |
517 | \&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will |
552 | \&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will |
518 | override the flags completely if it is found in the environment. This is |
553 | override the flags completely if it is found in the environment. This is |
519 | useful to try out specific backends to test their performance, or to work |
554 | useful to try out specific backends to test their performance, to work |
520 | around bugs. |
555 | around bugs, or to make libev threadsafe (accessing environment variables |
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556 | cannot be done in a threadsafe way, but usually it works if no other |
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557 | thread modifies them). |
521 | .ie n .IP """EVFLAG_FORKCHECK""" 4 |
558 | .ie n .IP """EVFLAG_FORKCHECK""" 4 |
522 | .el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4 |
559 | .el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4 |
523 | .IX Item "EVFLAG_FORKCHECK" |
560 | .IX Item "EVFLAG_FORKCHECK" |
524 | Instead of calling \f(CW\*(C`ev_loop_fork\*(C'\fR manually after a fork, you can also |
561 | Instead of calling \f(CW\*(C`ev_loop_fork\*(C'\fR manually after a fork, you can also |
525 | make libev check for a fork in each iteration by enabling this flag. |
562 | make libev check for a fork in each iteration by enabling this flag. |
526 | .Sp |
563 | .Sp |
527 | This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop, |
564 | This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop, |
528 | and thus this might slow down your event loop if you do a lot of loop |
565 | and thus this might slow down your event loop if you do a lot of loop |
529 | iterations and little real work, but is usually not noticeable (on my |
566 | iterations and little real work, but is usually not noticeable (on my |
530 | GNU/Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence |
567 | GNU/Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn |
531 | without a system call and thus \fIvery\fR fast, but my GNU/Linux system also has |
568 | sequence without a system call and thus \fIvery\fR fast, but my GNU/Linux |
532 | \&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster). |
569 | system also has \f(CW\*(C`pthread_atfork\*(C'\fR which is even faster). (Update: glibc |
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570 | versions 2.25 apparently removed the \f(CW\*(C`getpid\*(C'\fR optimisation again). |
533 | .Sp |
571 | .Sp |
534 | The big advantage of this flag is that you can forget about fork (and |
572 | The big advantage of this flag is that you can forget about fork (and |
535 | forget about forgetting to tell libev about forking) when you use this |
573 | forget about forgetting to tell libev about forking, although you still |
536 | flag. |
574 | have to ignore \f(CW\*(C`SIGPIPE\*(C'\fR) when you use this flag. |
537 | .Sp |
575 | .Sp |
538 | This flag setting cannot be overridden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR |
576 | This flag setting cannot be overridden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR |
539 | environment variable. |
577 | environment variable. |
540 | .ie n .IP """EVFLAG_NOINOTIFY""" 4 |
578 | .ie n .IP """EVFLAG_NOINOTIFY""" 4 |
541 | .el .IP "\f(CWEVFLAG_NOINOTIFY\fR" 4 |
579 | .el .IP "\f(CWEVFLAG_NOINOTIFY\fR" 4 |
… | |
… | |
572 | \&\f(CW\*(C`sigprocmask\*(C'\fR, whose behaviour is officially unspecified. |
610 | \&\f(CW\*(C`sigprocmask\*(C'\fR, whose behaviour is officially unspecified. |
573 | .Sp |
611 | .Sp |
574 | This flag's behaviour will become the default in future versions of libev. |
612 | This flag's behaviour will become the default in future versions of libev. |
575 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
613 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
576 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
614 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
577 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
615 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
578 | This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
616 | This is your standard \fBselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
579 | libev tries to roll its own fd_set with no limits on the number of fds, |
617 | libev tries to roll its own fd_set with no limits on the number of fds, |
580 | but if that fails, expect a fairly low limit on the number of fds when |
618 | but if that fails, expect a fairly low limit on the number of fds when |
581 | using this backend. It doesn't scale too well (O(highest_fd)), but its |
619 | using this backend. It doesn't scale too well (O(highest_fd)), but its |
582 | usually the fastest backend for a low number of (low-numbered :) fds. |
620 | usually the fastest backend for a low number of (low-numbered :) fds. |
583 | .Sp |
621 | .Sp |
… | |
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591 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR to the \f(CW\*(C`readfds\*(C'\fR set and \f(CW\*(C`EV_WRITE\*(C'\fR to the |
629 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR to the \f(CW\*(C`readfds\*(C'\fR set and \f(CW\*(C`EV_WRITE\*(C'\fR to the |
592 | \&\f(CW\*(C`writefds\*(C'\fR set (and to work around Microsoft Windows bugs, also onto the |
630 | \&\f(CW\*(C`writefds\*(C'\fR set (and to work around Microsoft Windows bugs, also onto the |
593 | \&\f(CW\*(C`exceptfds\*(C'\fR set on that platform). |
631 | \&\f(CW\*(C`exceptfds\*(C'\fR set on that platform). |
594 | .ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4 |
632 | .ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4 |
595 | .el .IP "\f(CWEVBACKEND_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4 |
633 | .el .IP "\f(CWEVBACKEND_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4 |
596 | .IX Item "EVBACKEND_POLL (value 2, poll backend, available everywhere except on windows)" |
634 | .IX Item "EVBACKEND_POLL (value 2, poll backend, available everywhere except on windows)" |
597 | And this is your standard \fIpoll\fR\|(2) backend. It's more complicated |
635 | And this is your standard \fBpoll\fR\|(2) backend. It's more complicated |
598 | than select, but handles sparse fds better and has no artificial |
636 | than select, but handles sparse fds better and has no artificial |
599 | limit on the number of fds you can use (except it will slow down |
637 | limit on the number of fds you can use (except it will slow down |
600 | considerably with a lot of inactive fds). It scales similarly to select, |
638 | considerably with a lot of inactive fds). It scales similarly to select, |
601 | i.e. O(total_fds). See the entry for \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR, above, for |
639 | i.e. O(total_fds). See the entry for \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR, above, for |
602 | performance tips. |
640 | performance tips. |
603 | .Sp |
641 | .Sp |
604 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR to \f(CW\*(C`POLLIN | POLLERR | POLLHUP\*(C'\fR, and |
642 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR to \f(CW\*(C`POLLIN | POLLERR | POLLHUP\*(C'\fR, and |
605 | \&\f(CW\*(C`EV_WRITE\*(C'\fR to \f(CW\*(C`POLLOUT | POLLERR | POLLHUP\*(C'\fR. |
643 | \&\f(CW\*(C`EV_WRITE\*(C'\fR to \f(CW\*(C`POLLOUT | POLLERR | POLLHUP\*(C'\fR. |
606 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
644 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
607 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
645 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
608 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
646 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
609 | Use the linux-specific \fIepoll\fR\|(7) interface (for both pre\- and post\-2.6.9 |
647 | Use the Linux-specific \fBepoll\fR\|(7) interface (for both pre\- and post\-2.6.9 |
610 | kernels). |
648 | kernels). |
611 | .Sp |
649 | .Sp |
612 | For few fds, this backend is a bit little slower than poll and select, but |
650 | For few fds, this backend is a bit little slower than poll and select, but |
613 | it scales phenomenally better. While poll and select usually scale like |
651 | it scales phenomenally better. While poll and select usually scale like |
614 | O(total_fds) where total_fds is the total number of fds (or the highest |
652 | O(total_fds) where total_fds is the total number of fds (or the highest |
… | |
… | |
660 | All this means that, in practice, \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR can be as fast or |
698 | All this means that, in practice, \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR can be as fast or |
661 | faster than epoll for maybe up to a hundred file descriptors, depending on |
699 | faster than epoll for maybe up to a hundred file descriptors, depending on |
662 | the usage. So sad. |
700 | the usage. So sad. |
663 | .Sp |
701 | .Sp |
664 | While nominally embeddable in other event loops, this feature is broken in |
702 | While nominally embeddable in other event loops, this feature is broken in |
665 | all kernel versions tested so far. |
703 | a lot of kernel revisions, but probably(!) works in current versions. |
|
|
704 | .Sp |
|
|
705 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
|
|
706 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
|
|
707 | .ie n .IP """EVBACKEND_LINUXAIO"" (value 64, Linux)" 4 |
|
|
708 | .el .IP "\f(CWEVBACKEND_LINUXAIO\fR (value 64, Linux)" 4 |
|
|
709 | .IX Item "EVBACKEND_LINUXAIO (value 64, Linux)" |
|
|
710 | Use the Linux-specific Linux \s-1AIO\s0 (\fInot\fR \f(CWaio(7)\fR but \f(CWio_submit(2)\fR) event interface available in post\-4.18 kernels (but libev |
|
|
711 | only tries to use it in 4.19+). |
|
|
712 | .Sp |
|
|
713 | This is another Linux train wreck of an event interface. |
|
|
714 | .Sp |
|
|
715 | If this backend works for you (as of this writing, it was very |
|
|
716 | experimental), it is the best event interface available on Linux and might |
|
|
717 | be well worth enabling it \- if it isn't available in your kernel this will |
|
|
718 | be detected and this backend will be skipped. |
|
|
719 | .Sp |
|
|
720 | This backend can batch oneshot requests and supports a user-space ring |
|
|
721 | buffer to receive events. It also doesn't suffer from most of the design |
|
|
722 | problems of epoll (such as not being able to remove event sources from |
|
|
723 | the epoll set), and generally sounds too good to be true. Because, this |
|
|
724 | being the Linux kernel, of course it suffers from a whole new set of |
|
|
725 | limitations, forcing you to fall back to epoll, inheriting all its design |
|
|
726 | issues. |
|
|
727 | .Sp |
|
|
728 | For one, it is not easily embeddable (but probably could be done using |
|
|
729 | an event fd at some extra overhead). It also is subject to a system wide |
|
|
730 | limit that can be configured in \fI/proc/sys/fs/aio\-max\-nr\fR. If no \s-1AIO\s0 |
|
|
731 | requests are left, this backend will be skipped during initialisation, and |
|
|
732 | will switch to epoll when the loop is active. |
|
|
733 | .Sp |
|
|
734 | Most problematic in practice, however, is that not all file descriptors |
|
|
735 | work with it. For example, in Linux 5.1, \s-1TCP\s0 sockets, pipes, event fds, |
|
|
736 | files, \fI/dev/null\fR and many others are supported, but ttys do not work |
|
|
737 | properly (a known bug that the kernel developers don't care about, see |
|
|
738 | <https://lore.kernel.org/patchwork/patch/1047453/>), so this is not |
|
|
739 | (yet?) a generic event polling interface. |
|
|
740 | .Sp |
|
|
741 | Overall, it seems the Linux developers just don't want it to have a |
|
|
742 | generic event handling mechanism other than \f(CW\*(C`select\*(C'\fR or \f(CW\*(C`poll\*(C'\fR. |
|
|
743 | .Sp |
|
|
744 | To work around all these problem, the current version of libev uses its |
|
|
745 | epoll backend as a fallback for file descriptor types that do not work. Or |
|
|
746 | falls back completely to epoll if the kernel acts up. |
666 | .Sp |
747 | .Sp |
667 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
748 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
668 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
749 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
669 | .ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 |
750 | .ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 |
670 | .el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 |
751 | .el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 |
671 | .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" |
752 | .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" |
672 | Kqueue deserves special mention, as at the time of this writing, it |
753 | Kqueue deserves special mention, as at the time this backend was |
673 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
754 | implemented, it was broken on all BSDs except NetBSD (usually it doesn't |
674 | with anything but sockets and pipes, except on Darwin, where of course |
755 | work reliably with anything but sockets and pipes, except on Darwin, |
675 | it's completely useless). Unlike epoll, however, whose brokenness |
756 | where of course it's completely useless). Unlike epoll, however, whose |
676 | is by design, these kqueue bugs can (and eventually will) be fixed |
757 | brokenness is by design, these kqueue bugs can be (and mostly have been) |
677 | without \s-1API\s0 changes to existing programs. For this reason it's not being |
758 | fixed without \s-1API\s0 changes to existing programs. For this reason it's not |
678 | \&\*(L"auto-detected\*(R" unless you explicitly specify it in the flags (i.e. using |
759 | being \*(L"auto-detected\*(R" on all platforms unless you explicitly specify it |
679 | \&\f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR) or libev was compiled on a known-to-be-good (\-enough) |
760 | in the flags (i.e. using \f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR) or libev was compiled on a |
680 | system like NetBSD. |
761 | known-to-be-good (\-enough) system like NetBSD. |
681 | .Sp |
762 | .Sp |
682 | You still can embed kqueue into a normal poll or select backend and use it |
763 | You still can embed kqueue into a normal poll or select backend and use it |
683 | only for sockets (after having made sure that sockets work with kqueue on |
764 | only for sockets (after having made sure that sockets work with kqueue on |
684 | the target platform). See \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
765 | the target platform). See \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
685 | .Sp |
766 | .Sp |
686 | It scales in the same way as the epoll backend, but the interface to the |
767 | It scales in the same way as the epoll backend, but the interface to the |
687 | kernel is more efficient (which says nothing about its actual speed, of |
768 | kernel is more efficient (which says nothing about its actual speed, of |
688 | course). While stopping, setting and starting an I/O watcher does never |
769 | course). While stopping, setting and starting an I/O watcher does never |
689 | cause an extra system call as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to |
770 | cause an extra system call as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to |
690 | two event changes per incident. Support for \f(CW\*(C`fork ()\*(C'\fR is very bad (you |
771 | two event changes per incident. Support for \f(CW\*(C`fork ()\*(C'\fR is very bad (you |
691 | might have to leak fd's on fork, but it's more sane than epoll) and it |
772 | might have to leak fds on fork, but it's more sane than epoll) and it |
692 | drops fds silently in similarly hard-to-detect cases. |
773 | drops fds silently in similarly hard-to-detect cases. |
693 | .Sp |
774 | .Sp |
694 | This backend usually performs well under most conditions. |
775 | This backend usually performs well under most conditions. |
695 | .Sp |
776 | .Sp |
696 | While nominally embeddable in other event loops, this doesn't work |
777 | While nominally embeddable in other event loops, this doesn't work |
697 | everywhere, so you might need to test for this. And since it is broken |
778 | everywhere, so you might need to test for this. And since it is broken |
698 | almost everywhere, you should only use it when you have a lot of sockets |
779 | almost everywhere, you should only use it when you have a lot of sockets |
699 | (for which it usually works), by embedding it into another event loop |
780 | (for which it usually works), by embedding it into another event loop |
700 | (e.g. \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR (but \f(CW\*(C`poll\*(C'\fR is of course |
781 | (e.g. \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR (but \f(CW\*(C`poll\*(C'\fR is of course |
701 | also broken on \s-1OS\s0 X)) and, did I mention it, using it only for sockets. |
782 | also broken on \s-1OS X\s0)) and, did I mention it, using it only for sockets. |
702 | .Sp |
783 | .Sp |
703 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR into an \f(CW\*(C`EVFILT_READ\*(C'\fR kevent with |
784 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR into an \f(CW\*(C`EVFILT_READ\*(C'\fR kevent with |
704 | \&\f(CW\*(C`NOTE_EOF\*(C'\fR, and \f(CW\*(C`EV_WRITE\*(C'\fR into an \f(CW\*(C`EVFILT_WRITE\*(C'\fR kevent with |
785 | \&\f(CW\*(C`NOTE_EOF\*(C'\fR, and \f(CW\*(C`EV_WRITE\*(C'\fR into an \f(CW\*(C`EVFILT_WRITE\*(C'\fR kevent with |
705 | \&\f(CW\*(C`NOTE_EOF\*(C'\fR. |
786 | \&\f(CW\*(C`NOTE_EOF\*(C'\fR. |
706 | .ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 |
787 | .ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 |
… | |
… | |
710 | implementation). According to reports, \f(CW\*(C`/dev/poll\*(C'\fR only supports sockets |
791 | implementation). According to reports, \f(CW\*(C`/dev/poll\*(C'\fR only supports sockets |
711 | and is not embeddable, which would limit the usefulness of this backend |
792 | and is not embeddable, which would limit the usefulness of this backend |
712 | immensely. |
793 | immensely. |
713 | .ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 |
794 | .ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 |
714 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
795 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
715 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
796 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
716 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
797 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
717 | it's really slow, but it still scales very well (O(active_fds)). |
798 | it's really slow, but it still scales very well (O(active_fds)). |
718 | .Sp |
799 | .Sp |
719 | While this backend scales well, it requires one system call per active |
800 | While this backend scales well, it requires one system call per active |
720 | file descriptor per loop iteration. For small and medium numbers of file |
801 | file descriptor per loop iteration. For small and medium numbers of file |
… | |
… | |
774 | used if available. |
855 | used if available. |
775 | .Sp |
856 | .Sp |
776 | .Vb 1 |
857 | .Vb 1 |
777 | \& struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE); |
858 | \& struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE); |
778 | .Ve |
859 | .Ve |
|
|
860 | .Sp |
|
|
861 | Example: Similarly, on linux, you mgiht want to take advantage of the |
|
|
862 | linux aio backend if possible, but fall back to something else if that |
|
|
863 | isn't available. |
|
|
864 | .Sp |
|
|
865 | .Vb 1 |
|
|
866 | \& struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_LINUXAIO); |
|
|
867 | .Ve |
779 | .RE |
868 | .RE |
780 | .IP "ev_loop_destroy (loop)" 4 |
869 | .IP "ev_loop_destroy (loop)" 4 |
781 | .IX Item "ev_loop_destroy (loop)" |
870 | .IX Item "ev_loop_destroy (loop)" |
782 | Destroys an event loop object (frees all memory and kernel state |
871 | Destroys an event loop object (frees all memory and kernel state |
783 | etc.). None of the active event watchers will be stopped in the normal |
872 | etc.). None of the active event watchers will be stopped in the normal |
… | |
… | |
799 | except in the rare occasion where you really need to free its resources. |
888 | except in the rare occasion where you really need to free its resources. |
800 | If you need dynamically allocated loops it is better to use \f(CW\*(C`ev_loop_new\*(C'\fR |
889 | If you need dynamically allocated loops it is better to use \f(CW\*(C`ev_loop_new\*(C'\fR |
801 | and \f(CW\*(C`ev_loop_destroy\*(C'\fR. |
890 | and \f(CW\*(C`ev_loop_destroy\*(C'\fR. |
802 | .IP "ev_loop_fork (loop)" 4 |
891 | .IP "ev_loop_fork (loop)" 4 |
803 | .IX Item "ev_loop_fork (loop)" |
892 | .IX Item "ev_loop_fork (loop)" |
804 | This function sets a flag that causes subsequent \f(CW\*(C`ev_run\*(C'\fR iterations to |
893 | This function sets a flag that causes subsequent \f(CW\*(C`ev_run\*(C'\fR iterations |
805 | reinitialise the kernel state for backends that have one. Despite the |
894 | to reinitialise the kernel state for backends that have one. Despite |
806 | name, you can call it anytime, but it makes most sense after forking, in |
895 | the name, you can call it anytime you are allowed to start or stop |
807 | the child process. You \fImust\fR call it (or use \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR) in the |
896 | watchers (except inside an \f(CW\*(C`ev_prepare\*(C'\fR callback), but it makes most |
808 | child before resuming or calling \f(CW\*(C`ev_run\*(C'\fR. |
897 | sense after forking, in the child process. You \fImust\fR call it (or use |
|
|
898 | \&\f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR) in the child before resuming or calling \f(CW\*(C`ev_run\*(C'\fR. |
809 | .Sp |
899 | .Sp |
|
|
900 | In addition, if you want to reuse a loop (via this function or |
|
|
901 | \&\f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR), you \fIalso\fR have to ignore \f(CW\*(C`SIGPIPE\*(C'\fR. |
|
|
902 | .Sp |
810 | Again, you \fIhave\fR to call it on \fIany\fR loop that you want to re-use after |
903 | Again, you \fIhave\fR to call it on \fIany\fR loop that you want to re-use after |
811 | a fork, \fIeven if you do not plan to use the loop in the parent\fR. This is |
904 | a fork, \fIeven if you do not plan to use the loop in the parent\fR. This is |
812 | because some kernel interfaces *cough* \fIkqueue\fR *cough* do funny things |
905 | because some kernel interfaces *cough* \fIkqueue\fR *cough* do funny things |
813 | during fork. |
906 | during fork. |
814 | .Sp |
907 | .Sp |
815 | On the other hand, you only need to call this function in the child |
908 | On the other hand, you only need to call this function in the child |
… | |
… | |
1349 | bug in your program. |
1442 | bug in your program. |
1350 | .Sp |
1443 | .Sp |
1351 | Libev will usually signal a few \*(L"dummy\*(R" events together with an error, for |
1444 | Libev will usually signal a few \*(L"dummy\*(R" events together with an error, for |
1352 | example it might indicate that a fd is readable or writable, and if your |
1445 | example it might indicate that a fd is readable or writable, and if your |
1353 | callbacks is well-written it can just attempt the operation and cope with |
1446 | callbacks is well-written it can just attempt the operation and cope with |
1354 | the error from \fIread()\fR or \fIwrite()\fR. This will not work in multi-threaded |
1447 | the error from \fBread()\fR or \fBwrite()\fR. This will not work in multi-threaded |
1355 | programs, though, as the fd could already be closed and reused for another |
1448 | programs, though, as the fd could already be closed and reused for another |
1356 | thing, so beware. |
1449 | thing, so beware. |
1357 | .SS "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0" |
1450 | .SS "\s-1GENERIC WATCHER FUNCTIONS\s0" |
1358 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
1451 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
1359 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
1452 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
1360 | .el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 |
1453 | .el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 |
1361 | .IX Item "ev_init (ev_TYPE *watcher, callback)" |
1454 | .IX Item "ev_init (ev_TYPE *watcher, callback)" |
1362 | This macro initialises the generic portion of a watcher. The contents |
1455 | This macro initialises the generic portion of a watcher. The contents |
… | |
… | |
1470 | or might not have been clamped to the valid range. |
1563 | or might not have been clamped to the valid range. |
1471 | .Sp |
1564 | .Sp |
1472 | The default priority used by watchers when no priority has been set is |
1565 | The default priority used by watchers when no priority has been set is |
1473 | always \f(CW0\fR, which is supposed to not be too high and not be too low :). |
1566 | always \f(CW0\fR, which is supposed to not be too high and not be too low :). |
1474 | .Sp |
1567 | .Sp |
1475 | See \*(L"\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0\*(R", below, for a more thorough treatment of |
1568 | See \*(L"\s-1WATCHER PRIORITY MODELS\*(R"\s0, below, for a more thorough treatment of |
1476 | priorities. |
1569 | priorities. |
1477 | .IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4 |
1570 | .IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4 |
1478 | .IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)" |
1571 | .IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)" |
1479 | Invoke the \f(CW\*(C`watcher\*(C'\fR with the given \f(CW\*(C`loop\*(C'\fR and \f(CW\*(C`revents\*(C'\fR. Neither |
1572 | Invoke the \f(CW\*(C`watcher\*(C'\fR with the given \f(CW\*(C`loop\*(C'\fR and \f(CW\*(C`revents\*(C'\fR. Neither |
1480 | \&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback |
1573 | \&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback |
… | |
… | |
1500 | not started in the first place. |
1593 | not started in the first place. |
1501 | .Sp |
1594 | .Sp |
1502 | See also \f(CW\*(C`ev_feed_fd_event\*(C'\fR and \f(CW\*(C`ev_feed_signal_event\*(C'\fR for related |
1595 | See also \f(CW\*(C`ev_feed_fd_event\*(C'\fR and \f(CW\*(C`ev_feed_signal_event\*(C'\fR for related |
1503 | functions that do not need a watcher. |
1596 | functions that do not need a watcher. |
1504 | .PP |
1597 | .PP |
1505 | See also the \*(L"\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0\*(R" and \*(L"\s-1BUILDING\s0 \s-1YOUR\s0 |
1598 | See also the \*(L"\s-1ASSOCIATING CUSTOM DATA WITH A WATCHER\*(R"\s0 and \*(L"\s-1BUILDING YOUR |
1506 | \&\s-1OWN\s0 \s-1COMPOSITE\s0 \s-1WATCHERS\s0\*(R" idioms. |
1599 | OWN COMPOSITE WATCHERS\*(R"\s0 idioms. |
1507 | .SS "\s-1WATCHER\s0 \s-1STATES\s0" |
1600 | .SS "\s-1WATCHER STATES\s0" |
1508 | .IX Subsection "WATCHER STATES" |
1601 | .IX Subsection "WATCHER STATES" |
1509 | There are various watcher states mentioned throughout this manual \- |
1602 | There are various watcher states mentioned throughout this manual \- |
1510 | active, pending and so on. In this section these states and the rules to |
1603 | active, pending and so on. In this section these states and the rules to |
1511 | transition between them will be described in more detail \- and while these |
1604 | transition between them will be described in more detail \- and while these |
1512 | rules might look complicated, they usually do \*(L"the right thing\*(R". |
1605 | rules might look complicated, they usually do \*(L"the right thing\*(R". |
… | |
… | |
1555 | .Sp |
1648 | .Sp |
1556 | While stopped (and not pending) the watcher is essentially in the |
1649 | While stopped (and not pending) the watcher is essentially in the |
1557 | initialised state, that is, it can be reused, moved, modified in any way |
1650 | initialised state, that is, it can be reused, moved, modified in any way |
1558 | you wish (but when you trash the memory block, you need to \f(CW\*(C`ev_TYPE_init\*(C'\fR |
1651 | you wish (but when you trash the memory block, you need to \f(CW\*(C`ev_TYPE_init\*(C'\fR |
1559 | it again). |
1652 | it again). |
1560 | .SS "\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0" |
1653 | .SS "\s-1WATCHER PRIORITY MODELS\s0" |
1561 | .IX Subsection "WATCHER PRIORITY MODELS" |
1654 | .IX Subsection "WATCHER PRIORITY MODELS" |
1562 | Many event loops support \fIwatcher priorities\fR, which are usually small |
1655 | Many event loops support \fIwatcher priorities\fR, which are usually small |
1563 | integers that influence the ordering of event callback invocation |
1656 | integers that influence the ordering of event callback invocation |
1564 | between watchers in some way, all else being equal. |
1657 | between watchers in some way, all else being equal. |
1565 | .PP |
1658 | .PP |
… | |
… | |
1710 | But really, best use non-blocking mode. |
1803 | But really, best use non-blocking mode. |
1711 | .PP |
1804 | .PP |
1712 | \fIThe special problem of disappearing file descriptors\fR |
1805 | \fIThe special problem of disappearing file descriptors\fR |
1713 | .IX Subsection "The special problem of disappearing file descriptors" |
1806 | .IX Subsection "The special problem of disappearing file descriptors" |
1714 | .PP |
1807 | .PP |
1715 | Some backends (e.g. kqueue, epoll) need to be told about closing a file |
1808 | Some backends (e.g. kqueue, epoll, linuxaio) need to be told about closing |
1716 | descriptor (either due to calling \f(CW\*(C`close\*(C'\fR explicitly or any other means, |
1809 | a file descriptor (either due to calling \f(CW\*(C`close\*(C'\fR explicitly or any other |
1717 | such as \f(CW\*(C`dup2\*(C'\fR). The reason is that you register interest in some file |
1810 | means, such as \f(CW\*(C`dup2\*(C'\fR). The reason is that you register interest in some |
1718 | descriptor, but when it goes away, the operating system will silently drop |
1811 | file descriptor, but when it goes away, the operating system will silently |
1719 | this interest. If another file descriptor with the same number then is |
1812 | drop this interest. If another file descriptor with the same number then |
1720 | registered with libev, there is no efficient way to see that this is, in |
1813 | is registered with libev, there is no efficient way to see that this is, |
1721 | fact, a different file descriptor. |
1814 | in fact, a different file descriptor. |
1722 | .PP |
1815 | .PP |
1723 | To avoid having to explicitly tell libev about such cases, libev follows |
1816 | To avoid having to explicitly tell libev about such cases, libev follows |
1724 | the following policy: Each time \f(CW\*(C`ev_io_set\*(C'\fR is being called, libev |
1817 | the following policy: Each time \f(CW\*(C`ev_io_set\*(C'\fR is being called, libev |
1725 | will assume that this is potentially a new file descriptor, otherwise |
1818 | will assume that this is potentially a new file descriptor, otherwise |
1726 | it is assumed that the file descriptor stays the same. That means that |
1819 | it is assumed that the file descriptor stays the same. That means that |
… | |
… | |
1763 | wish to read \- you would first have to request some data. |
1856 | wish to read \- you would first have to request some data. |
1764 | .PP |
1857 | .PP |
1765 | Since files are typically not-so-well supported by advanced notification |
1858 | Since files are typically not-so-well supported by advanced notification |
1766 | mechanism, libev tries hard to emulate \s-1POSIX\s0 behaviour with respect |
1859 | mechanism, libev tries hard to emulate \s-1POSIX\s0 behaviour with respect |
1767 | to files, even though you should not use it. The reason for this is |
1860 | to files, even though you should not use it. The reason for this is |
1768 | convenience: sometimes you want to watch \s-1STDIN\s0 or \s-1STDOUT\s0, which is |
1861 | convenience: sometimes you want to watch \s-1STDIN\s0 or \s-1STDOUT,\s0 which is |
1769 | usually a tty, often a pipe, but also sometimes files or special devices |
1862 | usually a tty, often a pipe, but also sometimes files or special devices |
1770 | (for example, \f(CW\*(C`epoll\*(C'\fR on Linux works with \fI/dev/random\fR but not with |
1863 | (for example, \f(CW\*(C`epoll\*(C'\fR on Linux works with \fI/dev/random\fR but not with |
1771 | \&\fI/dev/urandom\fR), and even though the file might better be served with |
1864 | \&\fI/dev/urandom\fR), and even though the file might better be served with |
1772 | asynchronous I/O instead of with non-blocking I/O, it is still useful when |
1865 | asynchronous I/O instead of with non-blocking I/O, it is still useful when |
1773 | it \*(L"just works\*(R" instead of freezing. |
1866 | it \*(L"just works\*(R" instead of freezing. |
1774 | .PP |
1867 | .PP |
1775 | So avoid file descriptors pointing to files when you know it (e.g. use |
1868 | So avoid file descriptors pointing to files when you know it (e.g. use |
1776 | libeio), but use them when it is convenient, e.g. for \s-1STDIN/STDOUT\s0, or |
1869 | libeio), but use them when it is convenient, e.g. for \s-1STDIN/STDOUT,\s0 or |
1777 | when you rarely read from a file instead of from a socket, and want to |
1870 | when you rarely read from a file instead of from a socket, and want to |
1778 | reuse the same code path. |
1871 | reuse the same code path. |
1779 | .PP |
1872 | .PP |
1780 | \fIThe special problem of fork\fR |
1873 | \fIThe special problem of fork\fR |
1781 | .IX Subsection "The special problem of fork" |
1874 | .IX Subsection "The special problem of fork" |
1782 | .PP |
1875 | .PP |
1783 | Some backends (epoll, kqueue) do not support \f(CW\*(C`fork ()\*(C'\fR at all or exhibit |
1876 | Some backends (epoll, kqueue, linuxaio, iouring) do not support \f(CW\*(C`fork ()\*(C'\fR |
1784 | useless behaviour. Libev fully supports fork, but needs to be told about |
1877 | at all or exhibit useless behaviour. Libev fully supports fork, but needs |
1785 | it in the child if you want to continue to use it in the child. |
1878 | to be told about it in the child if you want to continue to use it in the |
|
|
1879 | child. |
1786 | .PP |
1880 | .PP |
1787 | To support fork in your child processes, you have to call \f(CW\*(C`ev_loop_fork |
1881 | To support fork in your child processes, you have to call \f(CW\*(C`ev_loop_fork |
1788 | ()\*(C'\fR after a fork in the child, enable \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR, or resort to |
1882 | ()\*(C'\fR after a fork in the child, enable \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR, or resort to |
1789 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
1883 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
1790 | .PP |
1884 | .PP |
1791 | \fIThe special problem of \s-1SIGPIPE\s0\fR |
1885 | \fIThe special problem of \s-1SIGPIPE\s0\fR |
1792 | .IX Subsection "The special problem of SIGPIPE" |
1886 | .IX Subsection "The special problem of SIGPIPE" |
1793 | .PP |
1887 | .PP |
1794 | While not really specific to libev, it is easy to forget about \f(CW\*(C`SIGPIPE\*(C'\fR: |
1888 | While not really specific to libev, it is easy to forget about \f(CW\*(C`SIGPIPE\*(C'\fR: |
1795 | when writing to a pipe whose other end has been closed, your program gets |
1889 | when writing to a pipe whose other end has been closed, your program gets |
1796 | sent a \s-1SIGPIPE\s0, which, by default, aborts your program. For most programs |
1890 | sent a \s-1SIGPIPE,\s0 which, by default, aborts your program. For most programs |
1797 | this is sensible behaviour, for daemons, this is usually undesirable. |
1891 | this is sensible behaviour, for daemons, this is usually undesirable. |
1798 | .PP |
1892 | .PP |
1799 | So when you encounter spurious, unexplained daemon exits, make sure you |
1893 | So when you encounter spurious, unexplained daemon exits, make sure you |
1800 | ignore \s-1SIGPIPE\s0 (and maybe make sure you log the exit status of your daemon |
1894 | ignore \s-1SIGPIPE\s0 (and maybe make sure you log the exit status of your daemon |
1801 | somewhere, as that would have given you a big clue). |
1895 | somewhere, as that would have given you a big clue). |
1802 | .PP |
1896 | .PP |
1803 | \fIThe special problem of \fIaccept()\fIing when you can't\fR |
1897 | \fIThe special problem of \f(BIaccept()\fIing when you can't\fR |
1804 | .IX Subsection "The special problem of accept()ing when you can't" |
1898 | .IX Subsection "The special problem of accept()ing when you can't" |
1805 | .PP |
1899 | .PP |
1806 | Many implementations of the \s-1POSIX\s0 \f(CW\*(C`accept\*(C'\fR function (for example, |
1900 | Many implementations of the \s-1POSIX\s0 \f(CW\*(C`accept\*(C'\fR function (for example, |
1807 | found in post\-2004 Linux) have the peculiar behaviour of not removing a |
1901 | found in post\-2004 Linux) have the peculiar behaviour of not removing a |
1808 | connection from the pending queue in all error cases. |
1902 | connection from the pending queue in all error cases. |
… | |
… | |
2150 | .PP |
2244 | .PP |
2151 | The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR |
2245 | The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR |
2152 | time. This is usually the right thing as this timestamp refers to the time |
2246 | time. This is usually the right thing as this timestamp refers to the time |
2153 | of the event triggering whatever timeout you are modifying/starting. If |
2247 | of the event triggering whatever timeout you are modifying/starting. If |
2154 | you suspect event processing to be delayed and you \fIneed\fR to base the |
2248 | you suspect event processing to be delayed and you \fIneed\fR to base the |
2155 | timeout on the current time, use something like this to adjust for this: |
2249 | timeout on the current time, use something like the following to adjust |
|
|
2250 | for it: |
2156 | .PP |
2251 | .PP |
2157 | .Vb 1 |
2252 | .Vb 1 |
2158 | \& ev_timer_set (&timer, after + ev_now () \- ev_time (), 0.); |
2253 | \& ev_timer_set (&timer, after + (ev_time () \- ev_now ()), 0.); |
2159 | .Ve |
2254 | .Ve |
2160 | .PP |
2255 | .PP |
2161 | If the event loop is suspended for a long time, you can also force an |
2256 | If the event loop is suspended for a long time, you can also force an |
2162 | update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update |
2257 | update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update |
2163 | ()\*(C'\fR. |
2258 | ()\*(C'\fR, although that will push the event time of all outstanding events |
|
|
2259 | further into the future. |
2164 | .PP |
2260 | .PP |
2165 | \fIThe special problem of unsynchronised clocks\fR |
2261 | \fIThe special problem of unsynchronised clocks\fR |
2166 | .IX Subsection "The special problem of unsynchronised clocks" |
2262 | .IX Subsection "The special problem of unsynchronised clocks" |
2167 | .PP |
2263 | .PP |
2168 | Modern systems have a variety of clocks \- libev itself uses the normal |
2264 | Modern systems have a variety of clocks \- libev itself uses the normal |
… | |
… | |
2233 | .IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" |
2329 | .IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" |
2234 | .PD 0 |
2330 | .PD 0 |
2235 | .IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4 |
2331 | .IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4 |
2236 | .IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" |
2332 | .IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" |
2237 | .PD |
2333 | .PD |
2238 | Configure the timer to trigger after \f(CW\*(C`after\*(C'\fR seconds. If \f(CW\*(C`repeat\*(C'\fR |
2334 | Configure the timer to trigger after \f(CW\*(C`after\*(C'\fR seconds (fractional and |
2239 | is \f(CW0.\fR, then it will automatically be stopped once the timeout is |
2335 | negative values are supported). If \f(CW\*(C`repeat\*(C'\fR is \f(CW0.\fR, then it will |
2240 | reached. If it is positive, then the timer will automatically be |
2336 | automatically be stopped once the timeout is reached. If it is positive, |
2241 | configured to trigger again \f(CW\*(C`repeat\*(C'\fR seconds later, again, and again, |
2337 | then the timer will automatically be configured to trigger again \f(CW\*(C`repeat\*(C'\fR |
2242 | until stopped manually. |
2338 | seconds later, again, and again, until stopped manually. |
2243 | .Sp |
2339 | .Sp |
2244 | The timer itself will do a best-effort at avoiding drift, that is, if |
2340 | The timer itself will do a best-effort at avoiding drift, that is, if |
2245 | you configure a timer to trigger every 10 seconds, then it will normally |
2341 | you configure a timer to trigger every 10 seconds, then it will normally |
2246 | trigger at exactly 10 second intervals. If, however, your program cannot |
2342 | trigger at exactly 10 second intervals. If, however, your program cannot |
2247 | keep up with the timer (because it takes longer than those 10 seconds to |
2343 | keep up with the timer (because it takes longer than those 10 seconds to |
… | |
… | |
2329 | Periodic watchers are also timers of a kind, but they are very versatile |
2425 | Periodic watchers are also timers of a kind, but they are very versatile |
2330 | (and unfortunately a bit complex). |
2426 | (and unfortunately a bit complex). |
2331 | .PP |
2427 | .PP |
2332 | Unlike \f(CW\*(C`ev_timer\*(C'\fR, periodic watchers are not based on real time (or |
2428 | Unlike \f(CW\*(C`ev_timer\*(C'\fR, periodic watchers are not based on real time (or |
2333 | relative time, the physical time that passes) but on wall clock time |
2429 | relative time, the physical time that passes) but on wall clock time |
2334 | (absolute time, the thing you can read on your calender or clock). The |
2430 | (absolute time, the thing you can read on your calendar or clock). The |
2335 | difference is that wall clock time can run faster or slower than real |
2431 | difference is that wall clock time can run faster or slower than real |
2336 | time, and time jumps are not uncommon (e.g. when you adjust your |
2432 | time, and time jumps are not uncommon (e.g. when you adjust your |
2337 | wrist-watch). |
2433 | wrist-watch). |
2338 | .PP |
2434 | .PP |
2339 | You can tell a periodic watcher to trigger after some specific point |
2435 | You can tell a periodic watcher to trigger after some specific point |
… | |
… | |
2344 | \&\f(CW\*(C`ev_timer\*(C'\fR, which would still trigger roughly 10 seconds after starting |
2440 | \&\f(CW\*(C`ev_timer\*(C'\fR, which would still trigger roughly 10 seconds after starting |
2345 | it, as it uses a relative timeout). |
2441 | it, as it uses a relative timeout). |
2346 | .PP |
2442 | .PP |
2347 | \&\f(CW\*(C`ev_periodic\*(C'\fR watchers can also be used to implement vastly more complex |
2443 | \&\f(CW\*(C`ev_periodic\*(C'\fR watchers can also be used to implement vastly more complex |
2348 | timers, such as triggering an event on each \*(L"midnight, local time\*(R", or |
2444 | timers, such as triggering an event on each \*(L"midnight, local time\*(R", or |
2349 | other complicated rules. This cannot be done with \f(CW\*(C`ev_timer\*(C'\fR watchers, as |
2445 | other complicated rules. This cannot easily be done with \f(CW\*(C`ev_timer\*(C'\fR |
2350 | those cannot react to time jumps. |
2446 | watchers, as those cannot react to time jumps. |
2351 | .PP |
2447 | .PP |
2352 | As with timers, the callback is guaranteed to be invoked only when the |
2448 | As with timers, the callback is guaranteed to be invoked only when the |
2353 | point in time where it is supposed to trigger has passed. If multiple |
2449 | point in time where it is supposed to trigger has passed. If multiple |
2354 | timers become ready during the same loop iteration then the ones with |
2450 | timers become ready during the same loop iteration then the ones with |
2355 | earlier time-out values are invoked before ones with later time-out values |
2451 | earlier time-out values are invoked before ones with later time-out values |
… | |
… | |
2416 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`offset\*(C'\fR are both being |
2512 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`offset\*(C'\fR are both being |
2417 | ignored. Instead, each time the periodic watcher gets scheduled, the |
2513 | ignored. Instead, each time the periodic watcher gets scheduled, the |
2418 | reschedule callback will be called with the watcher as first, and the |
2514 | reschedule callback will be called with the watcher as first, and the |
2419 | current time as second argument. |
2515 | current time as second argument. |
2420 | .Sp |
2516 | .Sp |
2421 | \&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, ever, |
2517 | \&\s-1NOTE:\s0 \fIThis callback \s-1MUST NOT\s0 stop or destroy any periodic watcher, ever, |
2422 | or make \s-1ANY\s0 other event loop modifications whatsoever, unless explicitly |
2518 | or make \s-1ANY\s0 other event loop modifications whatsoever, unless explicitly |
2423 | allowed by documentation here\fR. |
2519 | allowed by documentation here\fR. |
2424 | .Sp |
2520 | .Sp |
2425 | If you need to stop it, return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop |
2521 | If you need to stop it, return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop |
2426 | it afterwards (e.g. by starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is the |
2522 | it afterwards (e.g. by starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is the |
… | |
… | |
2444 | .Sp |
2540 | .Sp |
2445 | \&\s-1NOTE:\s0 \fIThis callback must always return a time that is higher than or |
2541 | \&\s-1NOTE:\s0 \fIThis callback must always return a time that is higher than or |
2446 | equal to the passed \f(CI\*(C`now\*(C'\fI value\fR. |
2542 | equal to the passed \f(CI\*(C`now\*(C'\fI value\fR. |
2447 | .Sp |
2543 | .Sp |
2448 | This can be used to create very complex timers, such as a timer that |
2544 | This can be used to create very complex timers, such as a timer that |
2449 | triggers on \*(L"next midnight, local time\*(R". To do this, you would calculate the |
2545 | triggers on \*(L"next midnight, local time\*(R". To do this, you would calculate |
2450 | next midnight after \f(CW\*(C`now\*(C'\fR and return the timestamp value for this. How |
2546 | the next midnight after \f(CW\*(C`now\*(C'\fR and return the timestamp value for |
2451 | you do this is, again, up to you (but it is not trivial, which is the main |
2547 | this. Here is a (completely untested, no error checking) example on how to |
2452 | reason I omitted it as an example). |
2548 | do this: |
|
|
2549 | .Sp |
|
|
2550 | .Vb 1 |
|
|
2551 | \& #include <time.h> |
|
|
2552 | \& |
|
|
2553 | \& static ev_tstamp |
|
|
2554 | \& my_rescheduler (ev_periodic *w, ev_tstamp now) |
|
|
2555 | \& { |
|
|
2556 | \& time_t tnow = (time_t)now; |
|
|
2557 | \& struct tm tm; |
|
|
2558 | \& localtime_r (&tnow, &tm); |
|
|
2559 | \& |
|
|
2560 | \& tm.tm_sec = tm.tm_min = tm.tm_hour = 0; // midnight current day |
|
|
2561 | \& ++tm.tm_mday; // midnight next day |
|
|
2562 | \& |
|
|
2563 | \& return mktime (&tm); |
|
|
2564 | \& } |
|
|
2565 | .Ve |
|
|
2566 | .Sp |
|
|
2567 | Note: this code might run into trouble on days that have more then two |
|
|
2568 | midnights (beginning and end). |
2453 | .RE |
2569 | .RE |
2454 | .RS 4 |
2570 | .RS 4 |
2455 | .RE |
2571 | .RE |
2456 | .IP "ev_periodic_again (loop, ev_periodic *)" 4 |
2572 | .IP "ev_periodic_again (loop, ev_periodic *)" 4 |
2457 | .IX Item "ev_periodic_again (loop, ev_periodic *)" |
2573 | .IX Item "ev_periodic_again (loop, ev_periodic *)" |
… | |
… | |
2542 | only within the same loop, i.e. you can watch for \f(CW\*(C`SIGINT\*(C'\fR in your |
2658 | only within the same loop, i.e. you can watch for \f(CW\*(C`SIGINT\*(C'\fR in your |
2543 | default loop and for \f(CW\*(C`SIGIO\*(C'\fR in another loop, but you cannot watch for |
2659 | default loop and for \f(CW\*(C`SIGIO\*(C'\fR in another loop, but you cannot watch for |
2544 | \&\f(CW\*(C`SIGINT\*(C'\fR in both the default loop and another loop at the same time. At |
2660 | \&\f(CW\*(C`SIGINT\*(C'\fR in both the default loop and another loop at the same time. At |
2545 | the moment, \f(CW\*(C`SIGCHLD\*(C'\fR is permanently tied to the default loop. |
2661 | the moment, \f(CW\*(C`SIGCHLD\*(C'\fR is permanently tied to the default loop. |
2546 | .PP |
2662 | .PP |
2547 | When the first watcher gets started will libev actually register something |
2663 | Only after the first watcher for a signal is started will libev actually |
2548 | with the kernel (thus it coexists with your own signal handlers as long as |
2664 | register something with the kernel. It thus coexists with your own signal |
2549 | you don't register any with libev for the same signal). |
2665 | handlers as long as you don't register any with libev for the same signal. |
2550 | .PP |
2666 | .PP |
2551 | If possible and supported, libev will install its handlers with |
2667 | If possible and supported, libev will install its handlers with |
2552 | \&\f(CW\*(C`SA_RESTART\*(C'\fR (or equivalent) behaviour enabled, so system calls should |
2668 | \&\f(CW\*(C`SA_RESTART\*(C'\fR (or equivalent) behaviour enabled, so system calls should |
2553 | not be unduly interrupted. If you have a problem with system calls getting |
2669 | not be unduly interrupted. If you have a problem with system calls getting |
2554 | interrupted by signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher |
2670 | interrupted by signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher |
… | |
… | |
2615 | The signal the watcher watches out for. |
2731 | The signal the watcher watches out for. |
2616 | .PP |
2732 | .PP |
2617 | \fIExamples\fR |
2733 | \fIExamples\fR |
2618 | .IX Subsection "Examples" |
2734 | .IX Subsection "Examples" |
2619 | .PP |
2735 | .PP |
2620 | Example: Try to exit cleanly on \s-1SIGINT\s0. |
2736 | Example: Try to exit cleanly on \s-1SIGINT.\s0 |
2621 | .PP |
2737 | .PP |
2622 | .Vb 5 |
2738 | .Vb 5 |
2623 | \& static void |
2739 | \& static void |
2624 | \& sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2740 | \& sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2625 | \& { |
2741 | \& { |
… | |
… | |
2782 | compilation environment, which means that on systems with large file |
2898 | compilation environment, which means that on systems with large file |
2783 | support disabled by default, you get the 32 bit version of the stat |
2899 | support disabled by default, you get the 32 bit version of the stat |
2784 | structure. When using the library from programs that change the \s-1ABI\s0 to |
2900 | structure. When using the library from programs that change the \s-1ABI\s0 to |
2785 | use 64 bit file offsets the programs will fail. In that case you have to |
2901 | use 64 bit file offsets the programs will fail. In that case you have to |
2786 | compile libev with the same flags to get binary compatibility. This is |
2902 | compile libev with the same flags to get binary compatibility. This is |
2787 | obviously the case with any flags that change the \s-1ABI\s0, but the problem is |
2903 | obviously the case with any flags that change the \s-1ABI,\s0 but the problem is |
2788 | most noticeably displayed with ev_stat and large file support. |
2904 | most noticeably displayed with ev_stat and large file support. |
2789 | .PP |
2905 | .PP |
2790 | The solution for this is to lobby your distribution maker to make large |
2906 | The solution for this is to lobby your distribution maker to make large |
2791 | file interfaces available by default (as e.g. FreeBSD does) and not |
2907 | file interfaces available by default (as e.g. FreeBSD does) and not |
2792 | optional. Libev cannot simply switch on large file support because it has |
2908 | optional. Libev cannot simply switch on large file support because it has |
… | |
… | |
3037 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
3153 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
3038 | Prepare and check watchers are often (but not always) used in pairs: |
3154 | Prepare and check watchers are often (but not always) used in pairs: |
3039 | prepare watchers get invoked before the process blocks and check watchers |
3155 | prepare watchers get invoked before the process blocks and check watchers |
3040 | afterwards. |
3156 | afterwards. |
3041 | .PP |
3157 | .PP |
3042 | You \fImust not\fR call \f(CW\*(C`ev_run\*(C'\fR or similar functions that enter |
3158 | You \fImust not\fR call \f(CW\*(C`ev_run\*(C'\fR (or similar functions that enter the |
3043 | the current event loop from either \f(CW\*(C`ev_prepare\*(C'\fR or \f(CW\*(C`ev_check\*(C'\fR |
3159 | current event loop) or \f(CW\*(C`ev_loop_fork\*(C'\fR from either \f(CW\*(C`ev_prepare\*(C'\fR or |
3044 | watchers. Other loops than the current one are fine, however. The |
3160 | \&\f(CW\*(C`ev_check\*(C'\fR watchers. Other loops than the current one are fine, |
3045 | rationale behind this is that you do not need to check for recursion in |
3161 | however. The rationale behind this is that you do not need to check |
3046 | those watchers, i.e. the sequence will always be \f(CW\*(C`ev_prepare\*(C'\fR, blocking, |
3162 | for recursion in those watchers, i.e. the sequence will always be |
3047 | \&\f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each kind they will always be |
3163 | \&\f(CW\*(C`ev_prepare\*(C'\fR, blocking, \f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each |
3048 | called in pairs bracketing the blocking call. |
3164 | kind they will always be called in pairs bracketing the blocking call. |
3049 | .PP |
3165 | .PP |
3050 | Their main purpose is to integrate other event mechanisms into libev and |
3166 | Their main purpose is to integrate other event mechanisms into libev and |
3051 | their use is somewhat advanced. They could be used, for example, to track |
3167 | their use is somewhat advanced. They could be used, for example, to track |
3052 | variable changes, implement your own watchers, integrate net-snmp or a |
3168 | variable changes, implement your own watchers, integrate net-snmp or a |
3053 | coroutine library and lots more. They are also occasionally useful if |
3169 | coroutine library and lots more. They are also occasionally useful if |
… | |
… | |
3223 | .Ve |
3339 | .Ve |
3224 | .PP |
3340 | .PP |
3225 | Method 4: Do not use a prepare or check watcher because the module you |
3341 | Method 4: Do not use a prepare or check watcher because the module you |
3226 | want to embed is not flexible enough to support it. Instead, you can |
3342 | want to embed is not flexible enough to support it. Instead, you can |
3227 | override their poll function. The drawback with this solution is that the |
3343 | override their poll function. The drawback with this solution is that the |
3228 | main loop is now no longer controllable by \s-1EV\s0. The \f(CW\*(C`Glib::EV\*(C'\fR module uses |
3344 | main loop is now no longer controllable by \s-1EV.\s0 The \f(CW\*(C`Glib::EV\*(C'\fR module uses |
3229 | this approach, effectively embedding \s-1EV\s0 as a client into the horrible |
3345 | this approach, effectively embedding \s-1EV\s0 as a client into the horrible |
3230 | libglib event loop. |
3346 | libglib event loop. |
3231 | .PP |
3347 | .PP |
3232 | .Vb 4 |
3348 | .Vb 4 |
3233 | \& static gint |
3349 | \& static gint |
… | |
… | |
3347 | .PP |
3463 | .PP |
3348 | .Vb 3 |
3464 | .Vb 3 |
3349 | \& struct ev_loop *loop_hi = ev_default_init (0); |
3465 | \& struct ev_loop *loop_hi = ev_default_init (0); |
3350 | \& struct ev_loop *loop_lo = 0; |
3466 | \& struct ev_loop *loop_lo = 0; |
3351 | \& ev_embed embed; |
3467 | \& ev_embed embed; |
3352 | \& |
3468 | \& |
3353 | \& // see if there is a chance of getting one that works |
3469 | \& // see if there is a chance of getting one that works |
3354 | \& // (remember that a flags value of 0 means autodetection) |
3470 | \& // (remember that a flags value of 0 means autodetection) |
3355 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3471 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3356 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3472 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3357 | \& : 0; |
3473 | \& : 0; |
… | |
… | |
3373 | .PP |
3489 | .PP |
3374 | .Vb 3 |
3490 | .Vb 3 |
3375 | \& struct ev_loop *loop = ev_default_init (0); |
3491 | \& struct ev_loop *loop = ev_default_init (0); |
3376 | \& struct ev_loop *loop_socket = 0; |
3492 | \& struct ev_loop *loop_socket = 0; |
3377 | \& ev_embed embed; |
3493 | \& ev_embed embed; |
3378 | \& |
3494 | \& |
3379 | \& if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3495 | \& if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3380 | \& if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3496 | \& if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3381 | \& { |
3497 | \& { |
3382 | \& ev_embed_init (&embed, 0, loop_socket); |
3498 | \& ev_embed_init (&embed, 0, loop_socket); |
3383 | \& ev_embed_start (loop, &embed); |
3499 | \& ev_embed_start (loop, &embed); |
… | |
… | |
3400 | of course. |
3516 | of course. |
3401 | .PP |
3517 | .PP |
3402 | \fIThe special problem of life after fork \- how is it possible?\fR |
3518 | \fIThe special problem of life after fork \- how is it possible?\fR |
3403 | .IX Subsection "The special problem of life after fork - how is it possible?" |
3519 | .IX Subsection "The special problem of life after fork - how is it possible?" |
3404 | .PP |
3520 | .PP |
3405 | Most uses of \f(CW\*(C`fork()\*(C'\fR consist of forking, then some simple calls to set |
3521 | Most uses of \f(CW\*(C`fork ()\*(C'\fR consist of forking, then some simple calls to set |
3406 | up/change the process environment, followed by a call to \f(CW\*(C`exec()\*(C'\fR. This |
3522 | up/change the process environment, followed by a call to \f(CW\*(C`exec()\*(C'\fR. This |
3407 | sequence should be handled by libev without any problems. |
3523 | sequence should be handled by libev without any problems. |
3408 | .PP |
3524 | .PP |
3409 | This changes when the application actually wants to do event handling |
3525 | This changes when the application actually wants to do event handling |
3410 | in the child, or both parent in child, in effect \*(L"continuing\*(R" after the |
3526 | in the child, or both parent in child, in effect \*(L"continuing\*(R" after the |
… | |
… | |
3627 | is a time window between the event loop checking and resetting the async |
3743 | is a time window between the event loop checking and resetting the async |
3628 | notification, and the callback being invoked. |
3744 | notification, and the callback being invoked. |
3629 | .SH "OTHER FUNCTIONS" |
3745 | .SH "OTHER FUNCTIONS" |
3630 | .IX Header "OTHER FUNCTIONS" |
3746 | .IX Header "OTHER FUNCTIONS" |
3631 | There are some other functions of possible interest. Described. Here. Now. |
3747 | There are some other functions of possible interest. Described. Here. Now. |
3632 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 |
3748 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback, arg)" 4 |
3633 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" |
3749 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback, arg)" |
3634 | This function combines a simple timer and an I/O watcher, calls your |
3750 | This function combines a simple timer and an I/O watcher, calls your |
3635 | callback on whichever event happens first and automatically stops both |
3751 | callback on whichever event happens first and automatically stops both |
3636 | watchers. This is useful if you want to wait for a single event on an fd |
3752 | watchers. This is useful if you want to wait for a single event on an fd |
3637 | or timeout without having to allocate/configure/start/stop/free one or |
3753 | or timeout without having to allocate/configure/start/stop/free one or |
3638 | more watchers yourself. |
3754 | more watchers yourself. |
… | |
… | |
3650 | \&\f(CW\*(C`EV_ERROR\*(C'\fR, \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or \f(CW\*(C`EV_TIMER\*(C'\fR) and the \f(CW\*(C`arg\*(C'\fR |
3766 | \&\f(CW\*(C`EV_ERROR\*(C'\fR, \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or \f(CW\*(C`EV_TIMER\*(C'\fR) and the \f(CW\*(C`arg\*(C'\fR |
3651 | value passed to \f(CW\*(C`ev_once\*(C'\fR. Note that it is possible to receive \fIboth\fR |
3767 | value passed to \f(CW\*(C`ev_once\*(C'\fR. Note that it is possible to receive \fIboth\fR |
3652 | a timeout and an io event at the same time \- you probably should give io |
3768 | a timeout and an io event at the same time \- you probably should give io |
3653 | events precedence. |
3769 | events precedence. |
3654 | .Sp |
3770 | .Sp |
3655 | Example: wait up to ten seconds for data to appear on \s-1STDIN_FILENO\s0. |
3771 | Example: wait up to ten seconds for data to appear on \s-1STDIN_FILENO.\s0 |
3656 | .Sp |
3772 | .Sp |
3657 | .Vb 7 |
3773 | .Vb 7 |
3658 | \& static void stdin_ready (int revents, void *arg) |
3774 | \& static void stdin_ready (int revents, void *arg) |
3659 | \& { |
3775 | \& { |
3660 | \& if (revents & EV_READ) |
3776 | \& if (revents & EV_READ) |
… | |
… | |
3676 | .SH "COMMON OR USEFUL IDIOMS (OR BOTH)" |
3792 | .SH "COMMON OR USEFUL IDIOMS (OR BOTH)" |
3677 | .IX Header "COMMON OR USEFUL IDIOMS (OR BOTH)" |
3793 | .IX Header "COMMON OR USEFUL IDIOMS (OR BOTH)" |
3678 | This section explains some common idioms that are not immediately |
3794 | This section explains some common idioms that are not immediately |
3679 | obvious. Note that examples are sprinkled over the whole manual, and this |
3795 | obvious. Note that examples are sprinkled over the whole manual, and this |
3680 | section only contains stuff that wouldn't fit anywhere else. |
3796 | section only contains stuff that wouldn't fit anywhere else. |
3681 | .SS "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" |
3797 | .SS "\s-1ASSOCIATING CUSTOM DATA WITH A WATCHER\s0" |
3682 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
3798 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
3683 | Each watcher has, by default, a \f(CW\*(C`void *data\*(C'\fR member that you can read |
3799 | Each watcher has, by default, a \f(CW\*(C`void *data\*(C'\fR member that you can read |
3684 | or modify at any time: libev will completely ignore it. This can be used |
3800 | or modify at any time: libev will completely ignore it. This can be used |
3685 | to associate arbitrary data with your watcher. If you need more data and |
3801 | to associate arbitrary data with your watcher. If you need more data and |
3686 | don't want to allocate memory separately and store a pointer to it in that |
3802 | don't want to allocate memory separately and store a pointer to it in that |
… | |
… | |
3712 | \& } |
3828 | \& } |
3713 | .Ve |
3829 | .Ve |
3714 | .PP |
3830 | .PP |
3715 | More interesting and less C\-conformant ways of casting your callback |
3831 | More interesting and less C\-conformant ways of casting your callback |
3716 | function type instead have been omitted. |
3832 | function type instead have been omitted. |
3717 | .SS "\s-1BUILDING\s0 \s-1YOUR\s0 \s-1OWN\s0 \s-1COMPOSITE\s0 \s-1WATCHERS\s0" |
3833 | .SS "\s-1BUILDING YOUR OWN COMPOSITE WATCHERS\s0" |
3718 | .IX Subsection "BUILDING YOUR OWN COMPOSITE WATCHERS" |
3834 | .IX Subsection "BUILDING YOUR OWN COMPOSITE WATCHERS" |
3719 | Another common scenario is to use some data structure with multiple |
3835 | Another common scenario is to use some data structure with multiple |
3720 | embedded watchers, in effect creating your own watcher that combines |
3836 | embedded watchers, in effect creating your own watcher that combines |
3721 | multiple libev event sources into one \*(L"super-watcher\*(R": |
3837 | multiple libev event sources into one \*(L"super-watcher\*(R": |
3722 | .PP |
3838 | .PP |
… | |
… | |
3750 | \& { |
3866 | \& { |
3751 | \& struct my_biggy big = (struct my_biggy *) |
3867 | \& struct my_biggy big = (struct my_biggy *) |
3752 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
3868 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
3753 | \& } |
3869 | \& } |
3754 | .Ve |
3870 | .Ve |
3755 | .SS "\s-1AVOIDING\s0 \s-1FINISHING\s0 \s-1BEFORE\s0 \s-1RETURNING\s0" |
3871 | .SS "\s-1AVOIDING FINISHING BEFORE RETURNING\s0" |
3756 | .IX Subsection "AVOIDING FINISHING BEFORE RETURNING" |
3872 | .IX Subsection "AVOIDING FINISHING BEFORE RETURNING" |
3757 | Often you have structures like this in event-based programs: |
3873 | Often you have structures like this in event-based programs: |
3758 | .PP |
3874 | .PP |
3759 | .Vb 4 |
3875 | .Vb 4 |
3760 | \& callback () |
3876 | \& callback () |
… | |
… | |
3793 | \& ev_feed_event (EV_A_ watcher, 0); |
3909 | \& ev_feed_event (EV_A_ watcher, 0); |
3794 | .Ve |
3910 | .Ve |
3795 | .PP |
3911 | .PP |
3796 | This way, \f(CW\*(C`start_new_request\*(C'\fR can safely return before the callback is |
3912 | This way, \f(CW\*(C`start_new_request\*(C'\fR can safely return before the callback is |
3797 | invoked, while not delaying callback invocation too much. |
3913 | invoked, while not delaying callback invocation too much. |
3798 | .SS "\s-1MODEL/NESTED\s0 \s-1EVENT\s0 \s-1LOOP\s0 \s-1INVOCATIONS\s0 \s-1AND\s0 \s-1EXIT\s0 \s-1CONDITIONS\s0" |
3914 | .SS "\s-1MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS\s0" |
3799 | .IX Subsection "MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS" |
3915 | .IX Subsection "MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS" |
3800 | Often (especially in \s-1GUI\s0 toolkits) there are places where you have |
3916 | Often (especially in \s-1GUI\s0 toolkits) there are places where you have |
3801 | \&\fImodal\fR interaction, which is most easily implemented by recursively |
3917 | \&\fImodal\fR interaction, which is most easily implemented by recursively |
3802 | invoking \f(CW\*(C`ev_run\*(C'\fR. |
3918 | invoking \f(CW\*(C`ev_run\*(C'\fR. |
3803 | .PP |
3919 | .PP |
… | |
… | |
3835 | \& exit_main_loop = 1; |
3951 | \& exit_main_loop = 1; |
3836 | \& |
3952 | \& |
3837 | \& // exit both |
3953 | \& // exit both |
3838 | \& exit_main_loop = exit_nested_loop = 1; |
3954 | \& exit_main_loop = exit_nested_loop = 1; |
3839 | .Ve |
3955 | .Ve |
3840 | .SS "\s-1THREAD\s0 \s-1LOCKING\s0 \s-1EXAMPLE\s0" |
3956 | .SS "\s-1THREAD LOCKING EXAMPLE\s0" |
3841 | .IX Subsection "THREAD LOCKING EXAMPLE" |
3957 | .IX Subsection "THREAD LOCKING EXAMPLE" |
3842 | Here is a fictitious example of how to run an event loop in a different |
3958 | Here is a fictitious example of how to run an event loop in a different |
3843 | thread from where callbacks are being invoked and watchers are |
3959 | thread from where callbacks are being invoked and watchers are |
3844 | created/added/removed. |
3960 | created/added/removed. |
3845 | .PP |
3961 | .PP |
… | |
… | |
3986 | .PP |
4102 | .PP |
3987 | Note that sending the \f(CW\*(C`ev_async\*(C'\fR watcher is required because otherwise |
4103 | Note that sending the \f(CW\*(C`ev_async\*(C'\fR watcher is required because otherwise |
3988 | an event loop currently blocking in the kernel will have no knowledge |
4104 | an event loop currently blocking in the kernel will have no knowledge |
3989 | about the newly added timer. By waking up the loop it will pick up any new |
4105 | about the newly added timer. By waking up the loop it will pick up any new |
3990 | watchers in the next event loop iteration. |
4106 | watchers in the next event loop iteration. |
3991 | .SS "\s-1THREADS\s0, \s-1COROUTINES\s0, \s-1CONTINUATIONS\s0, \s-1QUEUES\s0... \s-1INSTEAD\s0 \s-1OF\s0 \s-1CALLBACKS\s0" |
4107 | .SS "\s-1THREADS, COROUTINES, CONTINUATIONS, QUEUES... INSTEAD OF CALLBACKS\s0" |
3992 | .IX Subsection "THREADS, COROUTINES, CONTINUATIONS, QUEUES... INSTEAD OF CALLBACKS" |
4108 | .IX Subsection "THREADS, COROUTINES, CONTINUATIONS, QUEUES... INSTEAD OF CALLBACKS" |
3993 | While the overhead of a callback that e.g. schedules a thread is small, it |
4109 | While the overhead of a callback that e.g. schedules a thread is small, it |
3994 | is still an overhead. If you embed libev, and your main usage is with some |
4110 | is still an overhead. If you embed libev, and your main usage is with some |
3995 | kind of threads or coroutines, you might want to customise libev so that |
4111 | kind of threads or coroutines, you might want to customise libev so that |
3996 | doesn't need callbacks anymore. |
4112 | doesn't need callbacks anymore. |
… | |
… | |
4032 | You can do similar tricks if you have, say, threads with an event queue \- |
4148 | You can do similar tricks if you have, say, threads with an event queue \- |
4033 | instead of storing a coroutine, you store the queue object and instead of |
4149 | instead of storing a coroutine, you store the queue object and instead of |
4034 | switching to a coroutine, you push the watcher onto the queue and notify |
4150 | switching to a coroutine, you push the watcher onto the queue and notify |
4035 | any waiters. |
4151 | any waiters. |
4036 | .PP |
4152 | .PP |
4037 | To embed libev, see \*(L"\s-1EMBEDDING\s0\*(R", but in short, it's easiest to create two |
4153 | To embed libev, see \*(L"\s-1EMBEDDING\*(R"\s0, but in short, it's easiest to create two |
4038 | files, \fImy_ev.h\fR and \fImy_ev.c\fR that include the respective libev files: |
4154 | files, \fImy_ev.h\fR and \fImy_ev.c\fR that include the respective libev files: |
4039 | .PP |
4155 | .PP |
4040 | .Vb 4 |
4156 | .Vb 4 |
4041 | \& // my_ev.h |
4157 | \& // my_ev.h |
4042 | \& #define EV_CB_DECLARE(type) struct my_coro *cb; |
4158 | \& #define EV_CB_DECLARE(type) struct my_coro *cb; |
4043 | \& #define EV_CB_INVOKE(watcher) switch_to ((watcher)\->cb); |
4159 | \& #define EV_CB_INVOKE(watcher) switch_to ((watcher)\->cb) |
4044 | \& #include "../libev/ev.h" |
4160 | \& #include "../libev/ev.h" |
4045 | \& |
4161 | \& |
4046 | \& // my_ev.c |
4162 | \& // my_ev.c |
4047 | \& #define EV_H "my_ev.h" |
4163 | \& #define EV_H "my_ev.h" |
4048 | \& #include "../libev/ev.c" |
4164 | \& #include "../libev/ev.c" |
… | |
… | |
4088 | The normal C \s-1API\s0 should work fine when used from \*(C+: both ev.h and the |
4204 | The normal C \s-1API\s0 should work fine when used from \*(C+: both ev.h and the |
4089 | libev sources can be compiled as \*(C+. Therefore, code that uses the C \s-1API\s0 |
4205 | libev sources can be compiled as \*(C+. Therefore, code that uses the C \s-1API\s0 |
4090 | will work fine. |
4206 | will work fine. |
4091 | .PP |
4207 | .PP |
4092 | Proper exception specifications might have to be added to callbacks passed |
4208 | Proper exception specifications might have to be added to callbacks passed |
4093 | to libev: exceptions may be thrown only from watcher callbacks, all |
4209 | to libev: exceptions may be thrown only from watcher callbacks, all other |
4094 | other callbacks (allocator, syserr, loop acquire/release and periodic |
4210 | callbacks (allocator, syserr, loop acquire/release and periodic reschedule |
4095 | reschedule callbacks) must not throw exceptions, and might need a \f(CW\*(C`throw |
4211 | callbacks) must not throw exceptions, and might need a \f(CW\*(C`noexcept\*(C'\fR |
4096 | ()\*(C'\fR specification. If you have code that needs to be compiled as both C |
4212 | specification. If you have code that needs to be compiled as both C and |
4097 | and \*(C+ you can use the \f(CW\*(C`EV_THROW\*(C'\fR macro for this: |
4213 | \&\*(C+ you can use the \f(CW\*(C`EV_NOEXCEPT\*(C'\fR macro for this: |
4098 | .PP |
4214 | .PP |
4099 | .Vb 6 |
4215 | .Vb 6 |
4100 | \& static void |
4216 | \& static void |
4101 | \& fatal_error (const char *msg) EV_THROW |
4217 | \& fatal_error (const char *msg) EV_NOEXCEPT |
4102 | \& { |
4218 | \& { |
4103 | \& perror (msg); |
4219 | \& perror (msg); |
4104 | \& abort (); |
4220 | \& abort (); |
4105 | \& } |
4221 | \& } |
4106 | \& |
4222 | \& |
… | |
… | |
4234 | \& void operator() (ev::io &w, int revents) |
4350 | \& void operator() (ev::io &w, int revents) |
4235 | \& { |
4351 | \& { |
4236 | \& ... |
4352 | \& ... |
4237 | \& } |
4353 | \& } |
4238 | \& } |
4354 | \& } |
4239 | \& |
4355 | \& |
4240 | \& myfunctor f; |
4356 | \& myfunctor f; |
4241 | \& |
4357 | \& |
4242 | \& ev::io w; |
4358 | \& ev::io w; |
4243 | \& w.set (&f); |
4359 | \& w.set (&f); |
4244 | .Ve |
4360 | .Ve |
… | |
… | |
4337 | there are additional modules that implement libev-compatible interfaces |
4453 | there are additional modules that implement libev-compatible interfaces |
4338 | to \f(CW\*(C`libadns\*(C'\fR (\f(CW\*(C`EV::ADNS\*(C'\fR, but \f(CW\*(C`AnyEvent::DNS\*(C'\fR is preferred nowadays), |
4454 | to \f(CW\*(C`libadns\*(C'\fR (\f(CW\*(C`EV::ADNS\*(C'\fR, but \f(CW\*(C`AnyEvent::DNS\*(C'\fR is preferred nowadays), |
4339 | \&\f(CW\*(C`Net::SNMP\*(C'\fR (\f(CW\*(C`Net::SNMP::EV\*(C'\fR) and the \f(CW\*(C`libglib\*(C'\fR event core (\f(CW\*(C`Glib::EV\*(C'\fR |
4455 | \&\f(CW\*(C`Net::SNMP\*(C'\fR (\f(CW\*(C`Net::SNMP::EV\*(C'\fR) and the \f(CW\*(C`libglib\*(C'\fR event core (\f(CW\*(C`Glib::EV\*(C'\fR |
4340 | and \f(CW\*(C`EV::Glib\*(C'\fR). |
4456 | and \f(CW\*(C`EV::Glib\*(C'\fR). |
4341 | .Sp |
4457 | .Sp |
4342 | It can be found and installed via \s-1CPAN\s0, its homepage is at |
4458 | It can be found and installed via \s-1CPAN,\s0 its homepage is at |
4343 | <http://software.schmorp.de/pkg/EV>. |
4459 | <http://software.schmorp.de/pkg/EV>. |
4344 | .IP "Python" 4 |
4460 | .IP "Python" 4 |
4345 | .IX Item "Python" |
4461 | .IX Item "Python" |
4346 | Python bindings can be found at <http://code.google.com/p/pyev/>. It |
4462 | Python bindings can be found at <http://code.google.com/p/pyev/>. It |
4347 | seems to be quite complete and well-documented. |
4463 | seems to be quite complete and well-documented. |
… | |
… | |
4355 | Roger Pack reports that using the link order \f(CW\*(C`\-lws2_32 \-lmsvcrt\-ruby\-190\*(C'\fR |
4471 | Roger Pack reports that using the link order \f(CW\*(C`\-lws2_32 \-lmsvcrt\-ruby\-190\*(C'\fR |
4356 | makes rev work even on mingw. |
4472 | makes rev work even on mingw. |
4357 | .IP "Haskell" 4 |
4473 | .IP "Haskell" 4 |
4358 | .IX Item "Haskell" |
4474 | .IX Item "Haskell" |
4359 | A haskell binding to libev is available at |
4475 | A haskell binding to libev is available at |
4360 | http://hackage.haskell.org/cgi\-bin/hackage\-scripts/package/hlibev <http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hlibev>. |
4476 | <http://hackage.haskell.org/cgi\-bin/hackage\-scripts/package/hlibev>. |
4361 | .IP "D" 4 |
4477 | .IP "D" 4 |
4362 | .IX Item "D" |
4478 | .IX Item "D" |
4363 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
4479 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
4364 | be found at <http://www.llucax.com.ar/proj/ev.d/index.html>. |
4480 | be found at <http://www.llucax.com.ar/proj/ev.d/index.html>. |
4365 | .IP "Ocaml" 4 |
4481 | .IP "Ocaml" 4 |
4366 | .IX Item "Ocaml" |
4482 | .IX Item "Ocaml" |
4367 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
4483 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
4368 | http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/ <http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
4484 | <http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/>. |
4369 | .IP "Lua" 4 |
4485 | .IP "Lua" 4 |
4370 | .IX Item "Lua" |
4486 | .IX Item "Lua" |
4371 | Brian Maher has written a partial interface to libev for lua (at the |
4487 | Brian Maher has written a partial interface to libev for lua (at the |
4372 | time of this writing, only \f(CW\*(C`ev_io\*(C'\fR and \f(CW\*(C`ev_timer\*(C'\fR), to be found at |
4488 | time of this writing, only \f(CW\*(C`ev_io\*(C'\fR and \f(CW\*(C`ev_timer\*(C'\fR), to be found at |
4373 | http://github.com/brimworks/lua\-ev <http://github.com/brimworks/lua-ev>. |
4489 | <http://github.com/brimworks/lua\-ev>. |
4374 | .IP "Javascript" 4 |
4490 | .IP "Javascript" 4 |
4375 | .IX Item "Javascript" |
4491 | .IX Item "Javascript" |
4376 | Node.js (<http://nodejs.org>) uses libev as the underlying event library. |
4492 | Node.js (<http://nodejs.org>) uses libev as the underlying event library. |
4377 | .IP "Others" 4 |
4493 | .IP "Others" 4 |
4378 | .IX Item "Others" |
4494 | .IX Item "Others" |
… | |
… | |
4467 | .SS "\s-1FILESETS\s0" |
4583 | .SS "\s-1FILESETS\s0" |
4468 | .IX Subsection "FILESETS" |
4584 | .IX Subsection "FILESETS" |
4469 | Depending on what features you need you need to include one or more sets of files |
4585 | Depending on what features you need you need to include one or more sets of files |
4470 | in your application. |
4586 | in your application. |
4471 | .PP |
4587 | .PP |
4472 | \fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR |
4588 | \fI\s-1CORE EVENT LOOP\s0\fR |
4473 | .IX Subsection "CORE EVENT LOOP" |
4589 | .IX Subsection "CORE EVENT LOOP" |
4474 | .PP |
4590 | .PP |
4475 | To include only the libev core (all the \f(CW\*(C`ev_*\*(C'\fR functions), with manual |
4591 | To include only the libev core (all the \f(CW\*(C`ev_*\*(C'\fR functions), with manual |
4476 | configuration (no autoconf): |
4592 | configuration (no autoconf): |
4477 | .PP |
4593 | .PP |
… | |
… | |
4504 | \& ev_vars.h |
4620 | \& ev_vars.h |
4505 | \& ev_wrap.h |
4621 | \& ev_wrap.h |
4506 | \& |
4622 | \& |
4507 | \& ev_win32.c required on win32 platforms only |
4623 | \& ev_win32.c required on win32 platforms only |
4508 | \& |
4624 | \& |
4509 | \& ev_select.c only when select backend is enabled (which is enabled by default) |
4625 | \& ev_select.c only when select backend is enabled |
4510 | \& ev_poll.c only when poll backend is enabled (disabled by default) |
4626 | \& ev_poll.c only when poll backend is enabled |
4511 | \& ev_epoll.c only when the epoll backend is enabled (disabled by default) |
4627 | \& ev_epoll.c only when the epoll backend is enabled |
|
|
4628 | \& ev_linuxaio.c only when the linux aio backend is enabled |
|
|
4629 | \& ev_iouring.c only when the linux io_uring backend is enabled |
4512 | \& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
4630 | \& ev_kqueue.c only when the kqueue backend is enabled |
4513 | \& ev_port.c only when the solaris port backend is enabled (disabled by default) |
4631 | \& ev_port.c only when the solaris port backend is enabled |
4514 | .Ve |
4632 | .Ve |
4515 | .PP |
4633 | .PP |
4516 | \&\fIev.c\fR includes the backend files directly when enabled, so you only need |
4634 | \&\fIev.c\fR includes the backend files directly when enabled, so you only need |
4517 | to compile this single file. |
4635 | to compile this single file. |
4518 | .PP |
4636 | .PP |
4519 | \fI\s-1LIBEVENT\s0 \s-1COMPATIBILITY\s0 \s-1API\s0\fR |
4637 | \fI\s-1LIBEVENT COMPATIBILITY API\s0\fR |
4520 | .IX Subsection "LIBEVENT COMPATIBILITY API" |
4638 | .IX Subsection "LIBEVENT COMPATIBILITY API" |
4521 | .PP |
4639 | .PP |
4522 | To include the libevent compatibility \s-1API\s0, also include: |
4640 | To include the libevent compatibility \s-1API,\s0 also include: |
4523 | .PP |
4641 | .PP |
4524 | .Vb 1 |
4642 | .Vb 1 |
4525 | \& #include "event.c" |
4643 | \& #include "event.c" |
4526 | .Ve |
4644 | .Ve |
4527 | .PP |
4645 | .PP |
… | |
… | |
4529 | .PP |
4647 | .PP |
4530 | .Vb 1 |
4648 | .Vb 1 |
4531 | \& #include "event.h" |
4649 | \& #include "event.h" |
4532 | .Ve |
4650 | .Ve |
4533 | .PP |
4651 | .PP |
4534 | in the files that want to use the libevent \s-1API\s0. This also includes \fIev.h\fR. |
4652 | in the files that want to use the libevent \s-1API.\s0 This also includes \fIev.h\fR. |
4535 | .PP |
4653 | .PP |
4536 | You need the following additional files for this: |
4654 | You need the following additional files for this: |
4537 | .PP |
4655 | .PP |
4538 | .Vb 2 |
4656 | .Vb 2 |
4539 | \& event.h |
4657 | \& event.h |
4540 | \& event.c |
4658 | \& event.c |
4541 | .Ve |
4659 | .Ve |
4542 | .PP |
4660 | .PP |
4543 | \fI\s-1AUTOCONF\s0 \s-1SUPPORT\s0\fR |
4661 | \fI\s-1AUTOCONF SUPPORT\s0\fR |
4544 | .IX Subsection "AUTOCONF SUPPORT" |
4662 | .IX Subsection "AUTOCONF SUPPORT" |
4545 | .PP |
4663 | .PP |
4546 | Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your configuration in |
4664 | Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your configuration in |
4547 | whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your |
4665 | whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your |
4548 | \&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then |
4666 | \&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then |
… | |
… | |
4551 | For this of course you need the m4 file: |
4669 | For this of course you need the m4 file: |
4552 | .PP |
4670 | .PP |
4553 | .Vb 1 |
4671 | .Vb 1 |
4554 | \& libev.m4 |
4672 | \& libev.m4 |
4555 | .Ve |
4673 | .Ve |
4556 | .SS "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" |
4674 | .SS "\s-1PREPROCESSOR SYMBOLS/MACROS\s0" |
4557 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
4675 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
4558 | Libev can be configured via a variety of preprocessor symbols you have to |
4676 | Libev can be configured via a variety of preprocessor symbols you have to |
4559 | define before including (or compiling) any of its files. The default in |
4677 | define before including (or compiling) any of its files. The default in |
4560 | the absence of autoconf is documented for every option. |
4678 | the absence of autoconf is documented for every option. |
4561 | .PP |
4679 | .PP |
4562 | Symbols marked with \*(L"(h)\*(R" do not change the \s-1ABI\s0, and can have different |
4680 | Symbols marked with \*(L"(h)\*(R" do not change the \s-1ABI,\s0 and can have different |
4563 | values when compiling libev vs. including \fIev.h\fR, so it is permissible |
4681 | values when compiling libev vs. including \fIev.h\fR, so it is permissible |
4564 | to redefine them before including \fIev.h\fR without breaking compatibility |
4682 | to redefine them before including \fIev.h\fR without breaking compatibility |
4565 | to a compiled library. All other symbols change the \s-1ABI\s0, which means all |
4683 | to a compiled library. All other symbols change the \s-1ABI,\s0 which means all |
4566 | users of libev and the libev code itself must be compiled with compatible |
4684 | users of libev and the libev code itself must be compiled with compatible |
4567 | settings. |
4685 | settings. |
4568 | .IP "\s-1EV_COMPAT3\s0 (h)" 4 |
4686 | .IP "\s-1EV_COMPAT3\s0 (h)" 4 |
4569 | .IX Item "EV_COMPAT3 (h)" |
4687 | .IX Item "EV_COMPAT3 (h)" |
4570 | Backwards compatibility is a major concern for libev. This is why this |
4688 | Backwards compatibility is a major concern for libev. This is why this |
… | |
… | |
4697 | If defined to be \f(CW1\fR, libev will compile in support for the Linux |
4815 | If defined to be \f(CW1\fR, libev will compile in support for the Linux |
4698 | \&\f(CW\*(C`epoll\*(C'\fR(7) backend. Its availability will be detected at runtime, |
4816 | \&\f(CW\*(C`epoll\*(C'\fR(7) backend. Its availability will be detected at runtime, |
4699 | otherwise another method will be used as fallback. This is the preferred |
4817 | otherwise another method will be used as fallback. This is the preferred |
4700 | backend for GNU/Linux systems. If undefined, it will be enabled if the |
4818 | backend for GNU/Linux systems. If undefined, it will be enabled if the |
4701 | headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
4819 | headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
|
|
4820 | .IP "\s-1EV_USE_LINUXAIO\s0" 4 |
|
|
4821 | .IX Item "EV_USE_LINUXAIO" |
|
|
4822 | If defined to be \f(CW1\fR, libev will compile in support for the Linux aio |
|
|
4823 | backend (\f(CW\*(C`EV_USE_EPOLL\*(C'\fR must also be enabled). If undefined, it will be |
|
|
4824 | enabled on linux, otherwise disabled. |
|
|
4825 | .IP "\s-1EV_USE_IOURING\s0" 4 |
|
|
4826 | .IX Item "EV_USE_IOURING" |
|
|
4827 | If defined to be \f(CW1\fR, libev will compile in support for the Linux |
|
|
4828 | io_uring backend (\f(CW\*(C`EV_USE_EPOLL\*(C'\fR must also be enabled). Due to it's |
|
|
4829 | current limitations it has to be requested explicitly. If undefined, it |
|
|
4830 | will be enabled on linux, otherwise disabled. |
4702 | .IP "\s-1EV_USE_KQUEUE\s0" 4 |
4831 | .IP "\s-1EV_USE_KQUEUE\s0" 4 |
4703 | .IX Item "EV_USE_KQUEUE" |
4832 | .IX Item "EV_USE_KQUEUE" |
4704 | If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style |
4833 | If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style |
4705 | \&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime, |
4834 | \&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime, |
4706 | otherwise another method will be used as fallback. This is the preferred |
4835 | otherwise another method will be used as fallback. This is the preferred |
… | |
… | |
4794 | all the priorities, so having many of them (hundreds) uses a lot of space |
4923 | all the priorities, so having many of them (hundreds) uses a lot of space |
4795 | and time, so using the defaults of five priorities (\-2 .. +2) is usually |
4924 | and time, so using the defaults of five priorities (\-2 .. +2) is usually |
4796 | fine. |
4925 | fine. |
4797 | .Sp |
4926 | .Sp |
4798 | If your embedding application does not need any priorities, defining these |
4927 | If your embedding application does not need any priorities, defining these |
4799 | both to \f(CW0\fR will save some memory and \s-1CPU\s0. |
4928 | both to \f(CW0\fR will save some memory and \s-1CPU.\s0 |
4800 | .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 |
4929 | .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 |
4801 | .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." |
4930 | .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." |
4802 | If undefined or defined to be \f(CW1\fR (and the platform supports it), then |
4931 | If undefined or defined to be \f(CW1\fR (and the platform supports it), then |
4803 | the respective watcher type is supported. If defined to be \f(CW0\fR, then it |
4932 | the respective watcher type is supported. If defined to be \f(CW0\fR, then it |
4804 | is not. Disabling watcher types mainly saves code size. |
4933 | is not. Disabling watcher types mainly saves code size. |
4805 | .IP "\s-1EV_FEATURES\s0" 4 |
4934 | .IP "\s-1EV_FEATURES\s0" 4 |
… | |
… | |
4963 | called. If set to \f(CW2\fR, then the internal verification code will be |
5092 | called. If set to \f(CW2\fR, then the internal verification code will be |
4964 | called once per loop, which can slow down libev. If set to \f(CW3\fR, then the |
5093 | called once per loop, which can slow down libev. If set to \f(CW3\fR, then the |
4965 | verification code will be called very frequently, which will slow down |
5094 | verification code will be called very frequently, which will slow down |
4966 | libev considerably. |
5095 | libev considerably. |
4967 | .Sp |
5096 | .Sp |
|
|
5097 | Verification errors are reported via C's \f(CW\*(C`assert\*(C'\fR mechanism, so if you |
|
|
5098 | disable that (e.g. by defining \f(CW\*(C`NDEBUG\*(C'\fR) then no errors will be reported. |
|
|
5099 | .Sp |
4968 | The default is \f(CW1\fR, unless \f(CW\*(C`EV_FEATURES\*(C'\fR overrides it, in which case it |
5100 | The default is \f(CW1\fR, unless \f(CW\*(C`EV_FEATURES\*(C'\fR overrides it, in which case it |
4969 | will be \f(CW0\fR. |
5101 | will be \f(CW0\fR. |
4970 | .IP "\s-1EV_COMMON\s0" 4 |
5102 | .IP "\s-1EV_COMMON\s0" 4 |
4971 | .IX Item "EV_COMMON" |
5103 | .IX Item "EV_COMMON" |
4972 | By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining |
5104 | By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining |
… | |
… | |
4993 | and the way callbacks are invoked and set. Must expand to a struct member |
5125 | and the way callbacks are invoked and set. Must expand to a struct member |
4994 | definition and a statement, respectively. See the \fIev.h\fR header file for |
5126 | definition and a statement, respectively. See the \fIev.h\fR header file for |
4995 | their default definitions. One possible use for overriding these is to |
5127 | their default definitions. One possible use for overriding these is to |
4996 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
5128 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
4997 | method calls instead of plain function calls in \*(C+. |
5129 | method calls instead of plain function calls in \*(C+. |
4998 | .SS "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0" |
5130 | .SS "\s-1EXPORTED API SYMBOLS\s0" |
4999 | .IX Subsection "EXPORTED API SYMBOLS" |
5131 | .IX Subsection "EXPORTED API SYMBOLS" |
5000 | If you need to re-export the \s-1API\s0 (e.g. via a \s-1DLL\s0) and you need a list of |
5132 | If you need to re-export the \s-1API\s0 (e.g. via a \s-1DLL\s0) and you need a list of |
5001 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
5133 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
5002 | all public symbols, one per line: |
5134 | all public symbols, one per line: |
5003 | .PP |
5135 | .PP |
… | |
… | |
5057 | \& #include "ev_cpp.h" |
5189 | \& #include "ev_cpp.h" |
5058 | \& #include "ev.c" |
5190 | \& #include "ev.c" |
5059 | .Ve |
5191 | .Ve |
5060 | .SH "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT" |
5192 | .SH "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT" |
5061 | .IX Header "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT" |
5193 | .IX Header "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT" |
5062 | .SS "\s-1THREADS\s0 \s-1AND\s0 \s-1COROUTINES\s0" |
5194 | .SS "\s-1THREADS AND COROUTINES\s0" |
5063 | .IX Subsection "THREADS AND COROUTINES" |
5195 | .IX Subsection "THREADS AND COROUTINES" |
5064 | \fI\s-1THREADS\s0\fR |
5196 | \fI\s-1THREADS\s0\fR |
5065 | .IX Subsection "THREADS" |
5197 | .IX Subsection "THREADS" |
5066 | .PP |
5198 | .PP |
5067 | All libev functions are reentrant and thread-safe unless explicitly |
5199 | All libev functions are reentrant and thread-safe unless explicitly |
… | |
… | |
5113 | An example use would be to communicate signals or other events that only |
5245 | An example use would be to communicate signals or other events that only |
5114 | work in the default loop by registering the signal watcher with the |
5246 | work in the default loop by registering the signal watcher with the |
5115 | default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop |
5247 | default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop |
5116 | watcher callback into the event loop interested in the signal. |
5248 | watcher callback into the event loop interested in the signal. |
5117 | .PP |
5249 | .PP |
5118 | See also \*(L"\s-1THREAD\s0 \s-1LOCKING\s0 \s-1EXAMPLE\s0\*(R". |
5250 | See also \*(L"\s-1THREAD LOCKING EXAMPLE\*(R"\s0. |
5119 | .PP |
5251 | .PP |
5120 | \fI\s-1COROUTINES\s0\fR |
5252 | \fI\s-1COROUTINES\s0\fR |
5121 | .IX Subsection "COROUTINES" |
5253 | .IX Subsection "COROUTINES" |
5122 | .PP |
5254 | .PP |
5123 | Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"): |
5255 | Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"): |
… | |
… | |
5128 | that you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. |
5260 | that you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. |
5129 | .PP |
5261 | .PP |
5130 | Care has been taken to ensure that libev does not keep local state inside |
5262 | Care has been taken to ensure that libev does not keep local state inside |
5131 | \&\f(CW\*(C`ev_run\*(C'\fR, and other calls do not usually allow for coroutine switches as |
5263 | \&\f(CW\*(C`ev_run\*(C'\fR, and other calls do not usually allow for coroutine switches as |
5132 | they do not call any callbacks. |
5264 | they do not call any callbacks. |
5133 | .SS "\s-1COMPILER\s0 \s-1WARNINGS\s0" |
5265 | .SS "\s-1COMPILER WARNINGS\s0" |
5134 | .IX Subsection "COMPILER WARNINGS" |
5266 | .IX Subsection "COMPILER WARNINGS" |
5135 | Depending on your compiler and compiler settings, you might get no or a |
5267 | Depending on your compiler and compiler settings, you might get no or a |
5136 | lot of warnings when compiling libev code. Some people are apparently |
5268 | lot of warnings when compiling libev code. Some people are apparently |
5137 | scared by this. |
5269 | scared by this. |
5138 | .PP |
5270 | .PP |
… | |
… | |
5190 | .PP |
5322 | .PP |
5191 | If you need, for some reason, empty reports from valgrind for your project |
5323 | If you need, for some reason, empty reports from valgrind for your project |
5192 | I suggest using suppression lists. |
5324 | I suggest using suppression lists. |
5193 | .SH "PORTABILITY NOTES" |
5325 | .SH "PORTABILITY NOTES" |
5194 | .IX Header "PORTABILITY NOTES" |
5326 | .IX Header "PORTABILITY NOTES" |
5195 | .SS "\s-1GNU/LINUX\s0 32 \s-1BIT\s0 \s-1LIMITATIONS\s0" |
5327 | .SS "\s-1GNU/LINUX 32 BIT LIMITATIONS\s0" |
5196 | .IX Subsection "GNU/LINUX 32 BIT LIMITATIONS" |
5328 | .IX Subsection "GNU/LINUX 32 BIT LIMITATIONS" |
5197 | GNU/Linux is the only common platform that supports 64 bit file/large file |
5329 | GNU/Linux is the only common platform that supports 64 bit file/large file |
5198 | interfaces but \fIdisables\fR them by default. |
5330 | interfaces but \fIdisables\fR them by default. |
5199 | .PP |
5331 | .PP |
5200 | That means that libev compiled in the default environment doesn't support |
5332 | That means that libev compiled in the default environment doesn't support |
5201 | files larger than 2GiB or so, which mainly affects \f(CW\*(C`ev_stat\*(C'\fR watchers. |
5333 | files larger than 2GiB or so, which mainly affects \f(CW\*(C`ev_stat\*(C'\fR watchers. |
5202 | .PP |
5334 | .PP |
5203 | Unfortunately, many programs try to work around this GNU/Linux issue |
5335 | Unfortunately, many programs try to work around this GNU/Linux issue |
5204 | by enabling the large file \s-1API\s0, which makes them incompatible with the |
5336 | by enabling the large file \s-1API,\s0 which makes them incompatible with the |
5205 | standard libev compiled for their system. |
5337 | standard libev compiled for their system. |
5206 | .PP |
5338 | .PP |
5207 | Likewise, libev cannot enable the large file \s-1API\s0 itself as this would |
5339 | Likewise, libev cannot enable the large file \s-1API\s0 itself as this would |
5208 | suddenly make it incompatible to the default compile time environment, |
5340 | suddenly make it incompatible to the default compile time environment, |
5209 | i.e. all programs not using special compile switches. |
5341 | i.e. all programs not using special compile switches. |
5210 | .SS "\s-1OS/X\s0 \s-1AND\s0 \s-1DARWIN\s0 \s-1BUGS\s0" |
5342 | .SS "\s-1OS/X AND DARWIN BUGS\s0" |
5211 | .IX Subsection "OS/X AND DARWIN BUGS" |
5343 | .IX Subsection "OS/X AND DARWIN BUGS" |
5212 | The whole thing is a bug if you ask me \- basically any system interface |
5344 | The whole thing is a bug if you ask me \- basically any system interface |
5213 | you touch is broken, whether it is locales, poll, kqueue or even the |
5345 | you touch is broken, whether it is locales, poll, kqueue or even the |
5214 | OpenGL drivers. |
5346 | OpenGL drivers. |
5215 | .PP |
5347 | .PP |
… | |
… | |
5237 | .PP |
5369 | .PP |
5238 | \fI\f(CI\*(C`select\*(C'\fI is buggy\fR |
5370 | \fI\f(CI\*(C`select\*(C'\fI is buggy\fR |
5239 | .IX Subsection "select is buggy" |
5371 | .IX Subsection "select is buggy" |
5240 | .PP |
5372 | .PP |
5241 | All that's left is \f(CW\*(C`select\*(C'\fR, and of course Apple found a way to fuck this |
5373 | All that's left is \f(CW\*(C`select\*(C'\fR, and of course Apple found a way to fuck this |
5242 | one up as well: On \s-1OS/X\s0, \f(CW\*(C`select\*(C'\fR actively limits the number of file |
5374 | one up as well: On \s-1OS/X,\s0 \f(CW\*(C`select\*(C'\fR actively limits the number of file |
5243 | descriptors you can pass in to 1024 \- your program suddenly crashes when |
5375 | descriptors you can pass in to 1024 \- your program suddenly crashes when |
5244 | you use more. |
5376 | you use more. |
5245 | .PP |
5377 | .PP |
5246 | There is an undocumented \*(L"workaround\*(R" for this \- defining |
5378 | There is an undocumented \*(L"workaround\*(R" for this \- defining |
5247 | \&\f(CW\*(C`_DARWIN_UNLIMITED_SELECT\*(C'\fR, which libev tries to use, so select \fIshould\fR |
5379 | \&\f(CW\*(C`_DARWIN_UNLIMITED_SELECT\*(C'\fR, which libev tries to use, so select \fIshould\fR |
5248 | work on \s-1OS/X\s0. |
5380 | work on \s-1OS/X.\s0 |
5249 | .SS "\s-1SOLARIS\s0 \s-1PROBLEMS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" |
5381 | .SS "\s-1SOLARIS PROBLEMS AND WORKAROUNDS\s0" |
5250 | .IX Subsection "SOLARIS PROBLEMS AND WORKAROUNDS" |
5382 | .IX Subsection "SOLARIS PROBLEMS AND WORKAROUNDS" |
5251 | \fI\f(CI\*(C`errno\*(C'\fI reentrancy\fR |
5383 | \fI\f(CI\*(C`errno\*(C'\fI reentrancy\fR |
5252 | .IX Subsection "errno reentrancy" |
5384 | .IX Subsection "errno reentrancy" |
5253 | .PP |
5385 | .PP |
5254 | The default compile environment on Solaris is unfortunately so |
5386 | The default compile environment on Solaris is unfortunately so |
… | |
… | |
5271 | great. |
5403 | great. |
5272 | .PP |
5404 | .PP |
5273 | If you can't get it to work, you can try running the program by setting |
5405 | If you can't get it to work, you can try running the program by setting |
5274 | the environment variable \f(CW\*(C`LIBEV_FLAGS=3\*(C'\fR to only allow \f(CW\*(C`poll\*(C'\fR and |
5406 | the environment variable \f(CW\*(C`LIBEV_FLAGS=3\*(C'\fR to only allow \f(CW\*(C`poll\*(C'\fR and |
5275 | \&\f(CW\*(C`select\*(C'\fR backends. |
5407 | \&\f(CW\*(C`select\*(C'\fR backends. |
5276 | .SS "\s-1AIX\s0 \s-1POLL\s0 \s-1BUG\s0" |
5408 | .SS "\s-1AIX POLL BUG\s0" |
5277 | .IX Subsection "AIX POLL BUG" |
5409 | .IX Subsection "AIX POLL BUG" |
5278 | \&\s-1AIX\s0 unfortunately has a broken \f(CW\*(C`poll.h\*(C'\fR header. Libev works around |
5410 | \&\s-1AIX\s0 unfortunately has a broken \f(CW\*(C`poll.h\*(C'\fR header. Libev works around |
5279 | this by trying to avoid the poll backend altogether (i.e. it's not even |
5411 | this by trying to avoid the poll backend altogether (i.e. it's not even |
5280 | compiled in), which normally isn't a big problem as \f(CW\*(C`select\*(C'\fR works fine |
5412 | compiled in), which normally isn't a big problem as \f(CW\*(C`select\*(C'\fR works fine |
5281 | with large bitsets on \s-1AIX\s0, and \s-1AIX\s0 is dead anyway. |
5413 | with large bitsets on \s-1AIX,\s0 and \s-1AIX\s0 is dead anyway. |
5282 | .SS "\s-1WIN32\s0 \s-1PLATFORM\s0 \s-1LIMITATIONS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" |
5414 | .SS "\s-1WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS\s0" |
5283 | .IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS" |
5415 | .IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS" |
5284 | \fIGeneral issues\fR |
5416 | \fIGeneral issues\fR |
5285 | .IX Subsection "General issues" |
5417 | .IX Subsection "General issues" |
5286 | .PP |
5418 | .PP |
5287 | Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev |
5419 | Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev |
… | |
… | |
5356 | \& #define EV_USE_SELECT 1 |
5488 | \& #define EV_USE_SELECT 1 |
5357 | \& #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
5489 | \& #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
5358 | .Ve |
5490 | .Ve |
5359 | .PP |
5491 | .PP |
5360 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
5492 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
5361 | complexity in the O(nA\*^X) range when using win32. |
5493 | complexity in the O(nX) range when using win32. |
5362 | .PP |
5494 | .PP |
5363 | \fILimited number of file descriptors\fR |
5495 | \fILimited number of file descriptors\fR |
5364 | .IX Subsection "Limited number of file descriptors" |
5496 | .IX Subsection "Limited number of file descriptors" |
5365 | .PP |
5497 | .PP |
5366 | Windows has numerous arbitrary (and low) limits on things. |
5498 | Windows has numerous arbitrary (and low) limits on things. |
… | |
… | |
5382 | by calling \f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR |
5514 | by calling \f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR |
5383 | (another arbitrary limit), but is broken in many versions of the Microsoft |
5515 | (another arbitrary limit), but is broken in many versions of the Microsoft |
5384 | runtime libraries. This might get you to about \f(CW512\fR or \f(CW2048\fR sockets |
5516 | runtime libraries. This might get you to about \f(CW512\fR or \f(CW2048\fR sockets |
5385 | (depending on windows version and/or the phase of the moon). To get more, |
5517 | (depending on windows version and/or the phase of the moon). To get more, |
5386 | you need to wrap all I/O functions and provide your own fd management, but |
5518 | you need to wrap all I/O functions and provide your own fd management, but |
5387 | the cost of calling select (O(nA\*^X)) will likely make this unworkable. |
5519 | the cost of calling select (O(nX)) will likely make this unworkable. |
5388 | .SS "\s-1PORTABILITY\s0 \s-1REQUIREMENTS\s0" |
5520 | .SS "\s-1PORTABILITY REQUIREMENTS\s0" |
5389 | .IX Subsection "PORTABILITY REQUIREMENTS" |
5521 | .IX Subsection "PORTABILITY REQUIREMENTS" |
5390 | In addition to a working ISO-C implementation and of course the |
5522 | In addition to a working ISO-C implementation and of course the |
5391 | backend-specific APIs, libev relies on a few additional extensions: |
5523 | backend-specific APIs, libev relies on a few additional extensions: |
5392 | .ie n .IP """void (*)(ev_watcher_type *, int revents)"" must have compatible calling conventions regardless of ""ev_watcher_type *""." 4 |
5524 | .ie n .IP """void (*)(ev_watcher_type *, int revents)"" must have compatible calling conventions regardless of ""ev_watcher_type *""." 4 |
5393 | .el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4 |
5525 | .el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4 |
5394 | .IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *." |
5526 | .IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *." |
5395 | Libev assumes not only that all watcher pointers have the same internal |
5527 | Libev assumes not only that all watcher pointers have the same internal |
5396 | structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO\s0 C for example), but it also |
5528 | structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO C\s0 for example), but it also |
5397 | assumes that the same (machine) code can be used to call any watcher |
5529 | assumes that the same (machine) code can be used to call any watcher |
5398 | callback: The watcher callbacks have different type signatures, but libev |
5530 | callback: The watcher callbacks have different type signatures, but libev |
5399 | calls them using an \f(CW\*(C`ev_watcher *\*(C'\fR internally. |
5531 | calls them using an \f(CW\*(C`ev_watcher *\*(C'\fR internally. |
|
|
5532 | .IP "null pointers and integer zero are represented by 0 bytes" 4 |
|
|
5533 | .IX Item "null pointers and integer zero are represented by 0 bytes" |
|
|
5534 | Libev uses \f(CW\*(C`memset\*(C'\fR to initialise structs and arrays to \f(CW0\fR bytes, and |
|
|
5535 | relies on this setting pointers and integers to null. |
5400 | .IP "pointer accesses must be thread-atomic" 4 |
5536 | .IP "pointer accesses must be thread-atomic" 4 |
5401 | .IX Item "pointer accesses must be thread-atomic" |
5537 | .IX Item "pointer accesses must be thread-atomic" |
5402 | Accessing a pointer value must be atomic, it must both be readable and |
5538 | Accessing a pointer value must be atomic, it must both be readable and |
5403 | writable in one piece \- this is the case on all current architectures. |
5539 | writable in one piece \- this is the case on all current architectures. |
5404 | .ie n .IP """sig_atomic_t volatile"" must be thread-atomic as well" 4 |
5540 | .ie n .IP """sig_atomic_t volatile"" must be thread-atomic as well" 4 |
… | |
… | |
5422 | except the initial one, and run the signal handling loop in the initial |
5558 | except the initial one, and run the signal handling loop in the initial |
5423 | thread as well. |
5559 | thread as well. |
5424 | .ie n .IP """long"" must be large enough for common memory allocation sizes" 4 |
5560 | .ie n .IP """long"" must be large enough for common memory allocation sizes" 4 |
5425 | .el .IP "\f(CWlong\fR must be large enough for common memory allocation sizes" 4 |
5561 | .el .IP "\f(CWlong\fR must be large enough for common memory allocation sizes" 4 |
5426 | .IX Item "long must be large enough for common memory allocation sizes" |
5562 | .IX Item "long must be large enough for common memory allocation sizes" |
5427 | To improve portability and simplify its \s-1API\s0, libev uses \f(CW\*(C`long\*(C'\fR internally |
5563 | To improve portability and simplify its \s-1API,\s0 libev uses \f(CW\*(C`long\*(C'\fR internally |
5428 | instead of \f(CW\*(C`size_t\*(C'\fR when allocating its data structures. On non-POSIX |
5564 | instead of \f(CW\*(C`size_t\*(C'\fR when allocating its data structures. On non-POSIX |
5429 | systems (Microsoft...) this might be unexpectedly low, but is still at |
5565 | systems (Microsoft...) this might be unexpectedly low, but is still at |
5430 | least 31 bits everywhere, which is enough for hundreds of millions of |
5566 | least 31 bits everywhere, which is enough for hundreds of millions of |
5431 | watchers. |
5567 | watchers. |
5432 | .ie n .IP """double"" must hold a time value in seconds with enough accuracy" 4 |
5568 | .ie n .IP """double"" must hold a time value in seconds with enough accuracy" 4 |
… | |
… | |
5434 | .IX Item "double must hold a time value in seconds with enough accuracy" |
5570 | .IX Item "double must hold a time value in seconds with enough accuracy" |
5435 | The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to |
5571 | The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to |
5436 | have at least 51 bits of mantissa (and 9 bits of exponent), which is |
5572 | have at least 51 bits of mantissa (and 9 bits of exponent), which is |
5437 | good enough for at least into the year 4000 with millisecond accuracy |
5573 | good enough for at least into the year 4000 with millisecond accuracy |
5438 | (the design goal for libev). This requirement is overfulfilled by |
5574 | (the design goal for libev). This requirement is overfulfilled by |
5439 | implementations using \s-1IEEE\s0 754, which is basically all existing ones. |
5575 | implementations using \s-1IEEE 754,\s0 which is basically all existing ones. |
5440 | .Sp |
5576 | .Sp |
5441 | With \s-1IEEE\s0 754 doubles, you get microsecond accuracy until at least the |
5577 | With \s-1IEEE 754\s0 doubles, you get microsecond accuracy until at least the |
5442 | year 2255 (and millisecond accuracy till the year 287396 \- by then, libev |
5578 | year 2255 (and millisecond accuracy till the year 287396 \- by then, libev |
5443 | is either obsolete or somebody patched it to use \f(CW\*(C`long double\*(C'\fR or |
5579 | is either obsolete or somebody patched it to use \f(CW\*(C`long double\*(C'\fR or |
5444 | something like that, just kidding). |
5580 | something like that, just kidding). |
5445 | .PP |
5581 | .PP |
5446 | If you know of other additional requirements drop me a note. |
5582 | If you know of other additional requirements drop me a note. |
… | |
… | |
5508 | calls in the current loop iteration and the loop is currently |
5644 | calls in the current loop iteration and the loop is currently |
5509 | blocked. Checking for async and signal events involves iterating over all |
5645 | blocked. Checking for async and signal events involves iterating over all |
5510 | running async watchers or all signal numbers. |
5646 | running async watchers or all signal numbers. |
5511 | .SH "PORTING FROM LIBEV 3.X TO 4.X" |
5647 | .SH "PORTING FROM LIBEV 3.X TO 4.X" |
5512 | .IX Header "PORTING FROM LIBEV 3.X TO 4.X" |
5648 | .IX Header "PORTING FROM LIBEV 3.X TO 4.X" |
5513 | The major version 4 introduced some incompatible changes to the \s-1API\s0. |
5649 | The major version 4 introduced some incompatible changes to the \s-1API.\s0 |
5514 | .PP |
5650 | .PP |
5515 | At the moment, the \f(CW\*(C`ev.h\*(C'\fR header file provides compatibility definitions |
5651 | At the moment, the \f(CW\*(C`ev.h\*(C'\fR header file provides compatibility definitions |
5516 | for all changes, so most programs should still compile. The compatibility |
5652 | for all changes, so most programs should still compile. The compatibility |
5517 | layer might be removed in later versions of libev, so better update to the |
5653 | layer might be removed in later versions of libev, so better update to the |
5518 | new \s-1API\s0 early than late. |
5654 | new \s-1API\s0 early than late. |
5519 | .ie n .IP """EV_COMPAT3"" backwards compatibility mechanism" 4 |
5655 | .ie n .IP """EV_COMPAT3"" backwards compatibility mechanism" 4 |
5520 | .el .IP "\f(CWEV_COMPAT3\fR backwards compatibility mechanism" 4 |
5656 | .el .IP "\f(CWEV_COMPAT3\fR backwards compatibility mechanism" 4 |
5521 | .IX Item "EV_COMPAT3 backwards compatibility mechanism" |
5657 | .IX Item "EV_COMPAT3 backwards compatibility mechanism" |
5522 | The backward compatibility mechanism can be controlled by |
5658 | The backward compatibility mechanism can be controlled by |
5523 | \&\f(CW\*(C`EV_COMPAT3\*(C'\fR. See \*(L"\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0\*(R" in the \*(L"\s-1EMBEDDING\s0\*(R" |
5659 | \&\f(CW\*(C`EV_COMPAT3\*(C'\fR. See \*(L"\s-1PREPROCESSOR SYMBOLS/MACROS\*(R"\s0 in the \*(L"\s-1EMBEDDING\*(R"\s0 |
5524 | section. |
5660 | section. |
5525 | .ie n .IP """ev_default_destroy"" and ""ev_default_fork"" have been removed" 4 |
5661 | .ie n .IP """ev_default_destroy"" and ""ev_default_fork"" have been removed" 4 |
5526 | .el .IP "\f(CWev_default_destroy\fR and \f(CWev_default_fork\fR have been removed" 4 |
5662 | .el .IP "\f(CWev_default_destroy\fR and \f(CWev_default_fork\fR have been removed" 4 |
5527 | .IX Item "ev_default_destroy and ev_default_fork have been removed" |
5663 | .IX Item "ev_default_destroy and ev_default_fork have been removed" |
5528 | These calls can be replaced easily by their \f(CW\*(C`ev_loop_xxx\*(C'\fR counterparts: |
5664 | These calls can be replaced easily by their \f(CW\*(C`ev_loop_xxx\*(C'\fR counterparts: |
… | |
… | |
5568 | .SH "GLOSSARY" |
5704 | .SH "GLOSSARY" |
5569 | .IX Header "GLOSSARY" |
5705 | .IX Header "GLOSSARY" |
5570 | .IP "active" 4 |
5706 | .IP "active" 4 |
5571 | .IX Item "active" |
5707 | .IX Item "active" |
5572 | A watcher is active as long as it has been started and not yet stopped. |
5708 | A watcher is active as long as it has been started and not yet stopped. |
5573 | See \*(L"\s-1WATCHER\s0 \s-1STATES\s0\*(R" for details. |
5709 | See \*(L"\s-1WATCHER STATES\*(R"\s0 for details. |
5574 | .IP "application" 4 |
5710 | .IP "application" 4 |
5575 | .IX Item "application" |
5711 | .IX Item "application" |
5576 | In this document, an application is whatever is using libev. |
5712 | In this document, an application is whatever is using libev. |
5577 | .IP "backend" 4 |
5713 | .IP "backend" 4 |
5578 | .IX Item "backend" |
5714 | .IX Item "backend" |
… | |
… | |
5605 | The model used to describe how an event loop handles and processes |
5741 | The model used to describe how an event loop handles and processes |
5606 | watchers and events. |
5742 | watchers and events. |
5607 | .IP "pending" 4 |
5743 | .IP "pending" 4 |
5608 | .IX Item "pending" |
5744 | .IX Item "pending" |
5609 | A watcher is pending as soon as the corresponding event has been |
5745 | A watcher is pending as soon as the corresponding event has been |
5610 | detected. See \*(L"\s-1WATCHER\s0 \s-1STATES\s0\*(R" for details. |
5746 | detected. See \*(L"\s-1WATCHER STATES\*(R"\s0 for details. |
5611 | .IP "real time" 4 |
5747 | .IP "real time" 4 |
5612 | .IX Item "real time" |
5748 | .IX Item "real time" |
5613 | The physical time that is observed. It is apparently strictly monotonic :) |
5749 | The physical time that is observed. It is apparently strictly monotonic :) |
5614 | .IP "wall-clock time" 4 |
5750 | .IP "wall-clock time" 4 |
5615 | .IX Item "wall-clock time" |
5751 | .IX Item "wall-clock time" |