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124 | .\" ======================================================================== |
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126 | .IX Title "LIBEV 3" |
135 | .IX Title "LIBEV 3" |
127 | .TH LIBEV 3 "2012-11-13" "libev-4.11" "libev - high performance full featured event loop" |
136 | .TH LIBEV 3 "2020-01-22" "libev-4.31" "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 |
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568 | want to handle signals only in specific threads and want to avoid libev |
606 | want to handle signals only in specific threads and want to avoid libev |
569 | unblocking the signals. |
607 | unblocking the signals. |
570 | .Sp |
608 | .Sp |
571 | It's also required by \s-1POSIX\s0 in a threaded program, as libev calls |
609 | It's also required by \s-1POSIX\s0 in a threaded program, as libev calls |
572 | \&\f(CW\*(C`sigprocmask\*(C'\fR, whose behaviour is officially unspecified. |
610 | \&\f(CW\*(C`sigprocmask\*(C'\fR, whose behaviour is officially unspecified. |
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611 | .ie n .IP """EVFLAG_NOTIMERFD""" 4 |
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612 | .el .IP "\f(CWEVFLAG_NOTIMERFD\fR" 4 |
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613 | .IX Item "EVFLAG_NOTIMERFD" |
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614 | When this flag is specified, the libev will avoid using a \f(CW\*(C`timerfd\*(C'\fR to |
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615 | detect time jumps. It will still be able to detect time jumps, but takes |
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616 | longer and has a lower accuracy in doing so, but saves a file descriptor |
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617 | per loop. |
573 | .Sp |
618 | .Sp |
574 | This flag's behaviour will become the default in future versions of libev. |
619 | The current implementation only tries to use a \f(CW\*(C`timerfd\*(C'\fR when the first |
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620 | \&\f(CW\*(C`ev_periodic\*(C'\fR watcher is started and falls back on other methods if it |
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621 | cannot be created, but this behaviour might change in the future. |
575 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
622 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
576 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
623 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
577 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
624 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
578 | This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
625 | 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, |
626 | 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 |
627 | 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 |
628 | 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. |
629 | usually the fastest backend for a low number of (low-numbered :) fds. |
583 | .Sp |
630 | .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 |
638 | 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 |
639 | \&\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). |
640 | \&\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 |
641 | .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 |
642 | .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)" |
643 | .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 |
644 | 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 |
645 | 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 |
646 | 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, |
647 | 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 |
648 | i.e. O(total_fds). See the entry for \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR, above, for |
602 | performance tips. |
649 | performance tips. |
603 | .Sp |
650 | .Sp |
604 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR to \f(CW\*(C`POLLIN | POLLERR | POLLHUP\*(C'\fR, and |
651 | 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. |
652 | \&\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 |
653 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
607 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
654 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
608 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
655 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
609 | Use the linux-specific \fIepoll\fR\|(7) interface (for both pre\- and post\-2.6.9 |
656 | Use the Linux-specific \fBepoll\fR\|(7) interface (for both pre\- and post\-2.6.9 |
610 | kernels). |
657 | kernels). |
611 | .Sp |
658 | .Sp |
612 | For few fds, this backend is a bit little slower than poll and select, but |
659 | 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 |
660 | 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 |
661 | 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 |
707 | 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 |
708 | faster than epoll for maybe up to a hundred file descriptors, depending on |
662 | the usage. So sad. |
709 | the usage. So sad. |
663 | .Sp |
710 | .Sp |
664 | While nominally embeddable in other event loops, this feature is broken in |
711 | While nominally embeddable in other event loops, this feature is broken in |
665 | all kernel versions tested so far. |
712 | a lot of kernel revisions, but probably(!) works in current versions. |
|
|
713 | .Sp |
|
|
714 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
|
|
715 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
|
|
716 | .ie n .IP """EVBACKEND_LINUXAIO"" (value 64, Linux)" 4 |
|
|
717 | .el .IP "\f(CWEVBACKEND_LINUXAIO\fR (value 64, Linux)" 4 |
|
|
718 | .IX Item "EVBACKEND_LINUXAIO (value 64, Linux)" |
|
|
719 | 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 |
|
|
720 | only tries to use it in 4.19+). |
|
|
721 | .Sp |
|
|
722 | This is another Linux train wreck of an event interface. |
|
|
723 | .Sp |
|
|
724 | If this backend works for you (as of this writing, it was very |
|
|
725 | experimental), it is the best event interface available on Linux and might |
|
|
726 | be well worth enabling it \- if it isn't available in your kernel this will |
|
|
727 | be detected and this backend will be skipped. |
|
|
728 | .Sp |
|
|
729 | This backend can batch oneshot requests and supports a user-space ring |
|
|
730 | buffer to receive events. It also doesn't suffer from most of the design |
|
|
731 | problems of epoll (such as not being able to remove event sources from |
|
|
732 | the epoll set), and generally sounds too good to be true. Because, this |
|
|
733 | being the Linux kernel, of course it suffers from a whole new set of |
|
|
734 | limitations, forcing you to fall back to epoll, inheriting all its design |
|
|
735 | issues. |
|
|
736 | .Sp |
|
|
737 | For one, it is not easily embeddable (but probably could be done using |
|
|
738 | an event fd at some extra overhead). It also is subject to a system wide |
|
|
739 | limit that can be configured in \fI/proc/sys/fs/aio\-max\-nr\fR. If no \s-1AIO\s0 |
|
|
740 | requests are left, this backend will be skipped during initialisation, and |
|
|
741 | will switch to epoll when the loop is active. |
|
|
742 | .Sp |
|
|
743 | Most problematic in practice, however, is that not all file descriptors |
|
|
744 | work with it. For example, in Linux 5.1, \s-1TCP\s0 sockets, pipes, event fds, |
|
|
745 | files, \fI/dev/null\fR and many others are supported, but ttys do not work |
|
|
746 | properly (a known bug that the kernel developers don't care about, see |
|
|
747 | <https://lore.kernel.org/patchwork/patch/1047453/>), so this is not |
|
|
748 | (yet?) a generic event polling interface. |
|
|
749 | .Sp |
|
|
750 | Overall, it seems the Linux developers just don't want it to have a |
|
|
751 | generic event handling mechanism other than \f(CW\*(C`select\*(C'\fR or \f(CW\*(C`poll\*(C'\fR. |
|
|
752 | .Sp |
|
|
753 | To work around all these problem, the current version of libev uses its |
|
|
754 | epoll backend as a fallback for file descriptor types that do not work. Or |
|
|
755 | falls back completely to epoll if the kernel acts up. |
666 | .Sp |
756 | .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 |
757 | 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. |
758 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
669 | .ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 |
759 | .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 |
760 | .el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 |
671 | .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" |
761 | .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" |
672 | Kqueue deserves special mention, as at the time of this writing, it |
762 | 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 |
763 | 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 |
764 | work reliably with anything but sockets and pipes, except on Darwin, |
675 | it's completely useless). Unlike epoll, however, whose brokenness |
765 | where of course it's completely useless). Unlike epoll, however, whose |
676 | is by design, these kqueue bugs can (and eventually will) be fixed |
766 | 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 |
767 | 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 |
768 | 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) |
769 | in the flags (i.e. using \f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR) or libev was compiled on a |
680 | system like NetBSD. |
770 | known-to-be-good (\-enough) system like NetBSD. |
681 | .Sp |
771 | .Sp |
682 | You still can embed kqueue into a normal poll or select backend and use it |
772 | 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 |
773 | 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. |
774 | the target platform). See \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
685 | .Sp |
775 | .Sp |
686 | It scales in the same way as the epoll backend, but the interface to the |
776 | 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 |
777 | 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 |
778 | 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 |
779 | 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 |
780 | 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 |
781 | 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 |
782 | drops fds silently in similarly hard-to-detect cases. |
693 | .Sp |
783 | .Sp |
694 | This backend usually performs well under most conditions. |
784 | This backend usually performs well under most conditions. |
695 | .Sp |
785 | .Sp |
696 | While nominally embeddable in other event loops, this doesn't work |
786 | 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 |
787 | 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 |
788 | 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 |
789 | (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 |
790 | (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. |
791 | also broken on \s-1OS X\s0)) and, did I mention it, using it only for sockets. |
702 | .Sp |
792 | .Sp |
703 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR into an \f(CW\*(C`EVFILT_READ\*(C'\fR kevent with |
793 | 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 |
794 | \&\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. |
795 | \&\f(CW\*(C`NOTE_EOF\*(C'\fR. |
706 | .ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 |
796 | .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 |
800 | 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 |
801 | and is not embeddable, which would limit the usefulness of this backend |
712 | immensely. |
802 | immensely. |
713 | .ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 |
803 | .ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 |
714 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
804 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
715 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
805 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
716 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
806 | 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)). |
807 | it's really slow, but it still scales very well (O(active_fds)). |
718 | .Sp |
808 | .Sp |
719 | While this backend scales well, it requires one system call per active |
809 | 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 |
810 | file descriptor per loop iteration. For small and medium numbers of file |
… | |
… | |
774 | used if available. |
864 | used if available. |
775 | .Sp |
865 | .Sp |
776 | .Vb 1 |
866 | .Vb 1 |
777 | \& struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE); |
867 | \& struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE); |
778 | .Ve |
868 | .Ve |
|
|
869 | .Sp |
|
|
870 | Example: Similarly, on linux, you mgiht want to take advantage of the |
|
|
871 | linux aio backend if possible, but fall back to something else if that |
|
|
872 | isn't available. |
|
|
873 | .Sp |
|
|
874 | .Vb 1 |
|
|
875 | \& struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_LINUXAIO); |
|
|
876 | .Ve |
779 | .RE |
877 | .RE |
780 | .IP "ev_loop_destroy (loop)" 4 |
878 | .IP "ev_loop_destroy (loop)" 4 |
781 | .IX Item "ev_loop_destroy (loop)" |
879 | .IX Item "ev_loop_destroy (loop)" |
782 | Destroys an event loop object (frees all memory and kernel state |
880 | 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 |
881 | 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. |
897 | 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 |
898 | 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. |
899 | and \f(CW\*(C`ev_loop_destroy\*(C'\fR. |
802 | .IP "ev_loop_fork (loop)" 4 |
900 | .IP "ev_loop_fork (loop)" 4 |
803 | .IX Item "ev_loop_fork (loop)" |
901 | .IX Item "ev_loop_fork (loop)" |
804 | This function sets a flag that causes subsequent \f(CW\*(C`ev_run\*(C'\fR iterations to |
902 | 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 |
903 | 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 |
904 | 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 |
905 | 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. |
906 | sense after forking, in the child process. You \fImust\fR call it (or use |
|
|
907 | \&\f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR) in the child before resuming or calling \f(CW\*(C`ev_run\*(C'\fR. |
809 | .Sp |
908 | .Sp |
|
|
909 | In addition, if you want to reuse a loop (via this function or |
|
|
910 | \&\f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR), you \fIalso\fR have to ignore \f(CW\*(C`SIGPIPE\*(C'\fR. |
|
|
911 | .Sp |
810 | Again, you \fIhave\fR to call it on \fIany\fR loop that you want to re-use after |
912 | 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 |
913 | 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 |
914 | because some kernel interfaces *cough* \fIkqueue\fR *cough* do funny things |
813 | during fork. |
915 | during fork. |
814 | .Sp |
916 | .Sp |
815 | On the other hand, you only need to call this function in the child |
917 | On the other hand, you only need to call this function in the child |
… | |
… | |
1349 | bug in your program. |
1451 | bug in your program. |
1350 | .Sp |
1452 | .Sp |
1351 | Libev will usually signal a few \*(L"dummy\*(R" events together with an error, for |
1453 | 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 |
1454 | 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 |
1455 | 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 |
1456 | 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 |
1457 | programs, though, as the fd could already be closed and reused for another |
1356 | thing, so beware. |
1458 | thing, so beware. |
1357 | .SS "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0" |
1459 | .SS "\s-1GENERIC WATCHER FUNCTIONS\s0" |
1358 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
1460 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
1359 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
1461 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
1360 | .el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 |
1462 | .el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 |
1361 | .IX Item "ev_init (ev_TYPE *watcher, callback)" |
1463 | .IX Item "ev_init (ev_TYPE *watcher, callback)" |
1362 | This macro initialises the generic portion of a watcher. The contents |
1464 | This macro initialises the generic portion of a watcher. The contents |
… | |
… | |
1470 | or might not have been clamped to the valid range. |
1572 | or might not have been clamped to the valid range. |
1471 | .Sp |
1573 | .Sp |
1472 | The default priority used by watchers when no priority has been set is |
1574 | 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 :). |
1575 | always \f(CW0\fR, which is supposed to not be too high and not be too low :). |
1474 | .Sp |
1576 | .Sp |
1475 | See \*(L"\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0\*(R", below, for a more thorough treatment of |
1577 | See \*(L"\s-1WATCHER PRIORITY MODELS\*(R"\s0, below, for a more thorough treatment of |
1476 | priorities. |
1578 | priorities. |
1477 | .IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4 |
1579 | .IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4 |
1478 | .IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)" |
1580 | .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 |
1581 | 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 |
1582 | \&\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. |
1602 | not started in the first place. |
1501 | .Sp |
1603 | .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 |
1604 | 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. |
1605 | functions that do not need a watcher. |
1504 | .PP |
1606 | .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 |
1607 | 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. |
1608 | OWN COMPOSITE WATCHERS\*(R"\s0 idioms. |
1507 | .SS "\s-1WATCHER\s0 \s-1STATES\s0" |
1609 | .SS "\s-1WATCHER STATES\s0" |
1508 | .IX Subsection "WATCHER STATES" |
1610 | .IX Subsection "WATCHER STATES" |
1509 | There are various watcher states mentioned throughout this manual \- |
1611 | There are various watcher states mentioned throughout this manual \- |
1510 | active, pending and so on. In this section these states and the rules to |
1612 | 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 |
1613 | 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". |
1614 | rules might look complicated, they usually do \*(L"the right thing\*(R". |
1513 | .IP "initialiased" 4 |
1615 | .IP "initialised" 4 |
1514 | .IX Item "initialiased" |
1616 | .IX Item "initialised" |
1515 | Before a watcher can be registered with the event loop it has to be |
1617 | Before a watcher can be registered with the event loop it has to be |
1516 | initialised. This can be done with a call to \f(CW\*(C`ev_TYPE_init\*(C'\fR, or calls to |
1618 | initialised. This can be done with a call to \f(CW\*(C`ev_TYPE_init\*(C'\fR, or calls to |
1517 | \&\f(CW\*(C`ev_init\*(C'\fR followed by the watcher-specific \f(CW\*(C`ev_TYPE_set\*(C'\fR function. |
1619 | \&\f(CW\*(C`ev_init\*(C'\fR followed by the watcher-specific \f(CW\*(C`ev_TYPE_set\*(C'\fR function. |
1518 | .Sp |
1620 | .Sp |
1519 | In this state it is simply some block of memory that is suitable for |
1621 | In this state it is simply some block of memory that is suitable for |
… | |
… | |
1555 | .Sp |
1657 | .Sp |
1556 | While stopped (and not pending) the watcher is essentially in the |
1658 | 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 |
1659 | 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 |
1660 | you wish (but when you trash the memory block, you need to \f(CW\*(C`ev_TYPE_init\*(C'\fR |
1559 | it again). |
1661 | it again). |
1560 | .SS "\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0" |
1662 | .SS "\s-1WATCHER PRIORITY MODELS\s0" |
1561 | .IX Subsection "WATCHER PRIORITY MODELS" |
1663 | .IX Subsection "WATCHER PRIORITY MODELS" |
1562 | Many event loops support \fIwatcher priorities\fR, which are usually small |
1664 | Many event loops support \fIwatcher priorities\fR, which are usually small |
1563 | integers that influence the ordering of event callback invocation |
1665 | integers that influence the ordering of event callback invocation |
1564 | between watchers in some way, all else being equal. |
1666 | between watchers in some way, all else being equal. |
1565 | .PP |
1667 | .PP |
1566 | In libev, Watcher priorities can be set using \f(CW\*(C`ev_set_priority\*(C'\fR. See its |
1668 | In libev, watcher priorities can be set using \f(CW\*(C`ev_set_priority\*(C'\fR. See its |
1567 | description for the more technical details such as the actual priority |
1669 | description for the more technical details such as the actual priority |
1568 | range. |
1670 | range. |
1569 | .PP |
1671 | .PP |
1570 | There are two common ways how these these priorities are being interpreted |
1672 | There are two common ways how these these priorities are being interpreted |
1571 | by event loops: |
1673 | by event loops: |
… | |
… | |
1665 | .IX Header "WATCHER TYPES" |
1767 | .IX Header "WATCHER TYPES" |
1666 | This section describes each watcher in detail, but will not repeat |
1768 | This section describes each watcher in detail, but will not repeat |
1667 | information given in the last section. Any initialisation/set macros, |
1769 | information given in the last section. Any initialisation/set macros, |
1668 | functions and members specific to the watcher type are explained. |
1770 | functions and members specific to the watcher type are explained. |
1669 | .PP |
1771 | .PP |
1670 | Members are additionally marked with either \fI[read\-only]\fR, meaning that, |
1772 | Most members are additionally marked with either \fI[read\-only]\fR, meaning |
1671 | while the watcher is active, you can look at the member and expect some |
1773 | that, while the watcher is active, you can look at the member and expect |
1672 | sensible content, but you must not modify it (you can modify it while the |
1774 | some sensible content, but you must not modify it (you can modify it while |
1673 | watcher is stopped to your hearts content), or \fI[read\-write]\fR, which |
1775 | the watcher is stopped to your hearts content), or \fI[read\-write]\fR, which |
1674 | means you can expect it to have some sensible content while the watcher |
1776 | means you can expect it to have some sensible content while the watcher |
1675 | is active, but you can also modify it. Modifying it may not do something |
1777 | is active, but you can also modify it. Modifying it may not do something |
1676 | sensible or take immediate effect (or do anything at all), but libev will |
1778 | sensible or take immediate effect (or do anything at all), but libev will |
1677 | not crash or malfunction in any way. |
1779 | not crash or malfunction in any way. |
|
|
1780 | .PP |
|
|
1781 | In any case, the documentation for each member will explain what the |
|
|
1782 | effects are, and if there are any additional access restrictions. |
1678 | .ie n .SS """ev_io"" \- is this file descriptor readable or writable?" |
1783 | .ie n .SS """ev_io"" \- is this file descriptor readable or writable?" |
1679 | .el .SS "\f(CWev_io\fP \- is this file descriptor readable or writable?" |
1784 | .el .SS "\f(CWev_io\fP \- is this file descriptor readable or writable?" |
1680 | .IX Subsection "ev_io - is this file descriptor readable or writable?" |
1785 | .IX Subsection "ev_io - is this file descriptor readable or writable?" |
1681 | I/O watchers check whether a file descriptor is readable or writable |
1786 | I/O watchers check whether a file descriptor is readable or writable |
1682 | in each iteration of the event loop, or, more precisely, when reading |
1787 | in each iteration of the event loop, or, more precisely, when reading |
… | |
… | |
1710 | But really, best use non-blocking mode. |
1815 | But really, best use non-blocking mode. |
1711 | .PP |
1816 | .PP |
1712 | \fIThe special problem of disappearing file descriptors\fR |
1817 | \fIThe special problem of disappearing file descriptors\fR |
1713 | .IX Subsection "The special problem of disappearing file descriptors" |
1818 | .IX Subsection "The special problem of disappearing file descriptors" |
1714 | .PP |
1819 | .PP |
1715 | Some backends (e.g. kqueue, epoll) need to be told about closing a file |
1820 | 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, |
1821 | 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 |
1822 | 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 |
1823 | 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 |
1824 | 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 |
1825 | is registered with libev, there is no efficient way to see that this is, |
1721 | fact, a different file descriptor. |
1826 | in fact, a different file descriptor. |
1722 | .PP |
1827 | .PP |
1723 | To avoid having to explicitly tell libev about such cases, libev follows |
1828 | 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 |
1829 | 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 |
1830 | 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 |
1831 | 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. |
1868 | wish to read \- you would first have to request some data. |
1764 | .PP |
1869 | .PP |
1765 | Since files are typically not-so-well supported by advanced notification |
1870 | Since files are typically not-so-well supported by advanced notification |
1766 | mechanism, libev tries hard to emulate \s-1POSIX\s0 behaviour with respect |
1871 | 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 |
1872 | 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 |
1873 | 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 |
1874 | 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 |
1875 | (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 |
1876 | \&\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 |
1877 | asynchronous I/O instead of with non-blocking I/O, it is still useful when |
1773 | it \*(L"just works\*(R" instead of freezing. |
1878 | it \*(L"just works\*(R" instead of freezing. |
1774 | .PP |
1879 | .PP |
1775 | So avoid file descriptors pointing to files when you know it (e.g. use |
1880 | 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 |
1881 | 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 |
1882 | when you rarely read from a file instead of from a socket, and want to |
1778 | reuse the same code path. |
1883 | reuse the same code path. |
1779 | .PP |
1884 | .PP |
1780 | \fIThe special problem of fork\fR |
1885 | \fIThe special problem of fork\fR |
1781 | .IX Subsection "The special problem of fork" |
1886 | .IX Subsection "The special problem of fork" |
1782 | .PP |
1887 | .PP |
1783 | Some backends (epoll, kqueue) do not support \f(CW\*(C`fork ()\*(C'\fR at all or exhibit |
1888 | 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 |
1889 | 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. |
1890 | to be told about it in the child if you want to continue to use it in the |
|
|
1891 | child. |
1786 | .PP |
1892 | .PP |
1787 | To support fork in your child processes, you have to call \f(CW\*(C`ev_loop_fork |
1893 | 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 |
1894 | ()\*(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. |
1895 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
1790 | .PP |
1896 | .PP |
1791 | \fIThe special problem of \s-1SIGPIPE\s0\fR |
1897 | \fIThe special problem of \s-1SIGPIPE\s0\fR |
1792 | .IX Subsection "The special problem of SIGPIPE" |
1898 | .IX Subsection "The special problem of SIGPIPE" |
1793 | .PP |
1899 | .PP |
1794 | While not really specific to libev, it is easy to forget about \f(CW\*(C`SIGPIPE\*(C'\fR: |
1900 | 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 |
1901 | 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 |
1902 | 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. |
1903 | this is sensible behaviour, for daemons, this is usually undesirable. |
1798 | .PP |
1904 | .PP |
1799 | So when you encounter spurious, unexplained daemon exits, make sure you |
1905 | 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 |
1906 | 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). |
1907 | somewhere, as that would have given you a big clue). |
1802 | .PP |
1908 | .PP |
1803 | \fIThe special problem of \fIaccept()\fIing when you can't\fR |
1909 | \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" |
1910 | .IX Subsection "The special problem of accept()ing when you can't" |
1805 | .PP |
1911 | .PP |
1806 | Many implementations of the \s-1POSIX\s0 \f(CW\*(C`accept\*(C'\fR function (for example, |
1912 | 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 |
1913 | found in post\-2004 Linux) have the peculiar behaviour of not removing a |
1808 | connection from the pending queue in all error cases. |
1914 | connection from the pending queue in all error cases. |
… | |
… | |
1849 | .IX Item "ev_io_set (ev_io *, int fd, int events)" |
1955 | .IX Item "ev_io_set (ev_io *, int fd, int events)" |
1850 | .PD |
1956 | .PD |
1851 | Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The \f(CW\*(C`fd\*(C'\fR is the file descriptor to |
1957 | Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The \f(CW\*(C`fd\*(C'\fR is the file descriptor to |
1852 | receive events for and \f(CW\*(C`events\*(C'\fR is either \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or |
1958 | receive events for and \f(CW\*(C`events\*(C'\fR is either \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or |
1853 | \&\f(CW\*(C`EV_READ | EV_WRITE\*(C'\fR, to express the desire to receive the given events. |
1959 | \&\f(CW\*(C`EV_READ | EV_WRITE\*(C'\fR, to express the desire to receive the given events. |
|
|
1960 | .IP "ev_io_modify (ev_io *, int events)" 4 |
|
|
1961 | .IX Item "ev_io_modify (ev_io *, int events)" |
|
|
1962 | Similar to \f(CW\*(C`ev_io_set\*(C'\fR, but only changes the event mask. Using this might |
|
|
1963 | be faster with some backends, as libev can assume that the \f(CW\*(C`fd\*(C'\fR still |
|
|
1964 | refers to the same underlying file description, something it cannot do |
|
|
1965 | when using \f(CW\*(C`ev_io_set\*(C'\fR. |
1854 | .IP "int fd [read\-only]" 4 |
1966 | .IP "int fd [no\-modify]" 4 |
1855 | .IX Item "int fd [read-only]" |
1967 | .IX Item "int fd [no-modify]" |
1856 | The file descriptor being watched. |
1968 | The file descriptor being watched. While it can be read at any time, you |
|
|
1969 | must not modify this member even when the watcher is stopped \- always use |
|
|
1970 | \&\f(CW\*(C`ev_io_set\*(C'\fR for that. |
1857 | .IP "int events [read\-only]" 4 |
1971 | .IP "int events [no\-modify]" 4 |
1858 | .IX Item "int events [read-only]" |
1972 | .IX Item "int events [no-modify]" |
1859 | The events being watched. |
1973 | The set of events being watched, among other flags. This field is a |
|
|
1974 | bit set \- to test for \f(CW\*(C`EV_READ\*(C'\fR, use \f(CW\*(C`w\->events & EV_READ\*(C'\fR, and |
|
|
1975 | similarly for \f(CW\*(C`EV_WRITE\*(C'\fR. |
|
|
1976 | .Sp |
|
|
1977 | As with \f(CW\*(C`fd\*(C'\fR, you must not modify this member even when the watcher is |
|
|
1978 | stopped, always use \f(CW\*(C`ev_io_set\*(C'\fR or \f(CW\*(C`ev_io_modify\*(C'\fR for that. |
1860 | .PP |
1979 | .PP |
1861 | \fIExamples\fR |
1980 | \fIExamples\fR |
1862 | .IX Subsection "Examples" |
1981 | .IX Subsection "Examples" |
1863 | .PP |
1982 | .PP |
1864 | Example: Call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well |
1983 | Example: Call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well |
… | |
… | |
2150 | .PP |
2269 | .PP |
2151 | The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR |
2270 | 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 |
2271 | 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 |
2272 | 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 |
2273 | 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: |
2274 | timeout on the current time, use something like the following to adjust |
|
|
2275 | for it: |
2156 | .PP |
2276 | .PP |
2157 | .Vb 1 |
2277 | .Vb 1 |
2158 | \& ev_timer_set (&timer, after + ev_now () \- ev_time (), 0.); |
2278 | \& ev_timer_set (&timer, after + (ev_time () \- ev_now ()), 0.); |
2159 | .Ve |
2279 | .Ve |
2160 | .PP |
2280 | .PP |
2161 | If the event loop is suspended for a long time, you can also force an |
2281 | 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 |
2282 | update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update |
2163 | ()\*(C'\fR. |
2283 | ()\*(C'\fR, although that will push the event time of all outstanding events |
|
|
2284 | further into the future. |
2164 | .PP |
2285 | .PP |
2165 | \fIThe special problem of unsynchronised clocks\fR |
2286 | \fIThe special problem of unsynchronised clocks\fR |
2166 | .IX Subsection "The special problem of unsynchronised clocks" |
2287 | .IX Subsection "The special problem of unsynchronised clocks" |
2167 | .PP |
2288 | .PP |
2168 | Modern systems have a variety of clocks \- libev itself uses the normal |
2289 | 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)" |
2354 | .IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" |
2234 | .PD 0 |
2355 | .PD 0 |
2235 | .IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4 |
2356 | .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)" |
2357 | .IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" |
2237 | .PD |
2358 | .PD |
2238 | Configure the timer to trigger after \f(CW\*(C`after\*(C'\fR seconds. If \f(CW\*(C`repeat\*(C'\fR |
2359 | 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 |
2360 | 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 |
2361 | 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, |
2362 | then the timer will automatically be configured to trigger again \f(CW\*(C`repeat\*(C'\fR |
2242 | until stopped manually. |
2363 | seconds later, again, and again, until stopped manually. |
2243 | .Sp |
2364 | .Sp |
2244 | The timer itself will do a best-effort at avoiding drift, that is, if |
2365 | 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 |
2366 | 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 |
2367 | 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 |
2368 | 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 |
2450 | Periodic watchers are also timers of a kind, but they are very versatile |
2330 | (and unfortunately a bit complex). |
2451 | (and unfortunately a bit complex). |
2331 | .PP |
2452 | .PP |
2332 | Unlike \f(CW\*(C`ev_timer\*(C'\fR, periodic watchers are not based on real time (or |
2453 | 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 |
2454 | 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 |
2455 | (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 |
2456 | 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 |
2457 | time, and time jumps are not uncommon (e.g. when you adjust your |
2337 | wrist-watch). |
2458 | wrist-watch). |
2338 | .PP |
2459 | .PP |
2339 | You can tell a periodic watcher to trigger after some specific point |
2460 | 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 |
2465 | \&\f(CW\*(C`ev_timer\*(C'\fR, which would still trigger roughly 10 seconds after starting |
2345 | it, as it uses a relative timeout). |
2466 | it, as it uses a relative timeout). |
2346 | .PP |
2467 | .PP |
2347 | \&\f(CW\*(C`ev_periodic\*(C'\fR watchers can also be used to implement vastly more complex |
2468 | \&\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 |
2469 | 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 |
2470 | other complicated rules. This cannot easily be done with \f(CW\*(C`ev_timer\*(C'\fR |
2350 | those cannot react to time jumps. |
2471 | watchers, as those cannot react to time jumps. |
2351 | .PP |
2472 | .PP |
2352 | As with timers, the callback is guaranteed to be invoked only when the |
2473 | 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 |
2474 | 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 |
2475 | 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 |
2476 | 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 |
2537 | 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 |
2538 | ignored. Instead, each time the periodic watcher gets scheduled, the |
2418 | reschedule callback will be called with the watcher as first, and the |
2539 | reschedule callback will be called with the watcher as first, and the |
2419 | current time as second argument. |
2540 | current time as second argument. |
2420 | .Sp |
2541 | .Sp |
2421 | \&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, ever, |
2542 | \&\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 |
2543 | or make \s-1ANY\s0 other event loop modifications whatsoever, unless explicitly |
2423 | allowed by documentation here\fR. |
2544 | allowed by documentation here\fR. |
2424 | .Sp |
2545 | .Sp |
2425 | If you need to stop it, return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop |
2546 | 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 |
2547 | it afterwards (e.g. by starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is the |
… | |
… | |
2444 | .Sp |
2565 | .Sp |
2445 | \&\s-1NOTE:\s0 \fIThis callback must always return a time that is higher than or |
2566 | \&\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. |
2567 | equal to the passed \f(CI\*(C`now\*(C'\fI value\fR. |
2447 | .Sp |
2568 | .Sp |
2448 | This can be used to create very complex timers, such as a timer that |
2569 | 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 |
2570 | 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 |
2571 | 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 |
2572 | this. Here is a (completely untested, no error checking) example on how to |
2452 | reason I omitted it as an example). |
2573 | do this: |
|
|
2574 | .Sp |
|
|
2575 | .Vb 1 |
|
|
2576 | \& #include <time.h> |
|
|
2577 | \& |
|
|
2578 | \& static ev_tstamp |
|
|
2579 | \& my_rescheduler (ev_periodic *w, ev_tstamp now) |
|
|
2580 | \& { |
|
|
2581 | \& time_t tnow = (time_t)now; |
|
|
2582 | \& struct tm tm; |
|
|
2583 | \& localtime_r (&tnow, &tm); |
|
|
2584 | \& |
|
|
2585 | \& tm.tm_sec = tm.tm_min = tm.tm_hour = 0; // midnight current day |
|
|
2586 | \& ++tm.tm_mday; // midnight next day |
|
|
2587 | \& |
|
|
2588 | \& return mktime (&tm); |
|
|
2589 | \& } |
|
|
2590 | .Ve |
|
|
2591 | .Sp |
|
|
2592 | Note: this code might run into trouble on days that have more then two |
|
|
2593 | midnights (beginning and end). |
2453 | .RE |
2594 | .RE |
2454 | .RS 4 |
2595 | .RS 4 |
2455 | .RE |
2596 | .RE |
2456 | .IP "ev_periodic_again (loop, ev_periodic *)" 4 |
2597 | .IP "ev_periodic_again (loop, ev_periodic *)" 4 |
2457 | .IX Item "ev_periodic_again (loop, ev_periodic *)" |
2598 | .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 |
2683 | 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 |
2684 | 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 |
2685 | \&\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. |
2686 | the moment, \f(CW\*(C`SIGCHLD\*(C'\fR is permanently tied to the default loop. |
2546 | .PP |
2687 | .PP |
2547 | When the first watcher gets started will libev actually register something |
2688 | 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 |
2689 | register something with the kernel. It thus coexists with your own signal |
2549 | you don't register any with libev for the same signal). |
2690 | handlers as long as you don't register any with libev for the same signal. |
2550 | .PP |
2691 | .PP |
2551 | If possible and supported, libev will install its handlers with |
2692 | 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 |
2693 | \&\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 |
2694 | 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 |
2695 | 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. |
2756 | The signal the watcher watches out for. |
2616 | .PP |
2757 | .PP |
2617 | \fIExamples\fR |
2758 | \fIExamples\fR |
2618 | .IX Subsection "Examples" |
2759 | .IX Subsection "Examples" |
2619 | .PP |
2760 | .PP |
2620 | Example: Try to exit cleanly on \s-1SIGINT\s0. |
2761 | Example: Try to exit cleanly on \s-1SIGINT.\s0 |
2621 | .PP |
2762 | .PP |
2622 | .Vb 5 |
2763 | .Vb 5 |
2623 | \& static void |
2764 | \& static void |
2624 | \& sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2765 | \& sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2625 | \& { |
2766 | \& { |
… | |
… | |
2740 | .ie n .SS """ev_stat"" \- did the file attributes just change?" |
2881 | .ie n .SS """ev_stat"" \- did the file attributes just change?" |
2741 | .el .SS "\f(CWev_stat\fP \- did the file attributes just change?" |
2882 | .el .SS "\f(CWev_stat\fP \- did the file attributes just change?" |
2742 | .IX Subsection "ev_stat - did the file attributes just change?" |
2883 | .IX Subsection "ev_stat - did the file attributes just change?" |
2743 | This watches a file system path for attribute changes. That is, it calls |
2884 | This watches a file system path for attribute changes. That is, it calls |
2744 | \&\f(CW\*(C`stat\*(C'\fR on that path in regular intervals (or when the \s-1OS\s0 says it changed) |
2885 | \&\f(CW\*(C`stat\*(C'\fR on that path in regular intervals (or when the \s-1OS\s0 says it changed) |
2745 | and sees if it changed compared to the last time, invoking the callback if |
2886 | and sees if it changed compared to the last time, invoking the callback |
2746 | it did. |
2887 | if it did. Starting the watcher \f(CW\*(C`stat\*(C'\fR's the file, so only changes that |
|
|
2888 | happen after the watcher has been started will be reported. |
2747 | .PP |
2889 | .PP |
2748 | The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does |
2890 | The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does |
2749 | not exist\*(R" is a status change like any other. The condition \*(L"path does not |
2891 | not exist\*(R" is a status change like any other. The condition \*(L"path does not |
2750 | exist\*(R" (or more correctly \*(L"path cannot be stat'ed\*(R") is signified by the |
2892 | exist\*(R" (or more correctly \*(L"path cannot be stat'ed\*(R") is signified by the |
2751 | \&\f(CW\*(C`st_nlink\*(C'\fR field being zero (which is otherwise always forced to be at |
2893 | \&\f(CW\*(C`st_nlink\*(C'\fR field being zero (which is otherwise always forced to be at |
… | |
… | |
2781 | compilation environment, which means that on systems with large file |
2923 | compilation environment, which means that on systems with large file |
2782 | support disabled by default, you get the 32 bit version of the stat |
2924 | support disabled by default, you get the 32 bit version of the stat |
2783 | structure. When using the library from programs that change the \s-1ABI\s0 to |
2925 | structure. When using the library from programs that change the \s-1ABI\s0 to |
2784 | use 64 bit file offsets the programs will fail. In that case you have to |
2926 | use 64 bit file offsets the programs will fail. In that case you have to |
2785 | compile libev with the same flags to get binary compatibility. This is |
2927 | compile libev with the same flags to get binary compatibility. This is |
2786 | obviously the case with any flags that change the \s-1ABI\s0, but the problem is |
2928 | obviously the case with any flags that change the \s-1ABI,\s0 but the problem is |
2787 | most noticeably displayed with ev_stat and large file support. |
2929 | most noticeably displayed with ev_stat and large file support. |
2788 | .PP |
2930 | .PP |
2789 | The solution for this is to lobby your distribution maker to make large |
2931 | The solution for this is to lobby your distribution maker to make large |
2790 | file interfaces available by default (as e.g. FreeBSD does) and not |
2932 | file interfaces available by default (as e.g. FreeBSD does) and not |
2791 | optional. Libev cannot simply switch on large file support because it has |
2933 | optional. Libev cannot simply switch on large file support because it has |
… | |
… | |
3036 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
3178 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
3037 | Prepare and check watchers are often (but not always) used in pairs: |
3179 | Prepare and check watchers are often (but not always) used in pairs: |
3038 | prepare watchers get invoked before the process blocks and check watchers |
3180 | prepare watchers get invoked before the process blocks and check watchers |
3039 | afterwards. |
3181 | afterwards. |
3040 | .PP |
3182 | .PP |
3041 | You \fImust not\fR call \f(CW\*(C`ev_run\*(C'\fR or similar functions that enter |
3183 | You \fImust not\fR call \f(CW\*(C`ev_run\*(C'\fR (or similar functions that enter the |
3042 | the current event loop from either \f(CW\*(C`ev_prepare\*(C'\fR or \f(CW\*(C`ev_check\*(C'\fR |
3184 | current event loop) or \f(CW\*(C`ev_loop_fork\*(C'\fR from either \f(CW\*(C`ev_prepare\*(C'\fR or |
3043 | watchers. Other loops than the current one are fine, however. The |
3185 | \&\f(CW\*(C`ev_check\*(C'\fR watchers. Other loops than the current one are fine, |
3044 | rationale behind this is that you do not need to check for recursion in |
3186 | however. The rationale behind this is that you do not need to check |
3045 | those watchers, i.e. the sequence will always be \f(CW\*(C`ev_prepare\*(C'\fR, blocking, |
3187 | for recursion in those watchers, i.e. the sequence will always be |
3046 | \&\f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each kind they will always be |
3188 | \&\f(CW\*(C`ev_prepare\*(C'\fR, blocking, \f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each |
3047 | called in pairs bracketing the blocking call. |
3189 | kind they will always be called in pairs bracketing the blocking call. |
3048 | .PP |
3190 | .PP |
3049 | Their main purpose is to integrate other event mechanisms into libev and |
3191 | Their main purpose is to integrate other event mechanisms into libev and |
3050 | their use is somewhat advanced. They could be used, for example, to track |
3192 | their use is somewhat advanced. They could be used, for example, to track |
3051 | variable changes, implement your own watchers, integrate net-snmp or a |
3193 | variable changes, implement your own watchers, integrate net-snmp or a |
3052 | coroutine library and lots more. They are also occasionally useful if |
3194 | coroutine library and lots more. They are also occasionally useful if |
… | |
… | |
3222 | .Ve |
3364 | .Ve |
3223 | .PP |
3365 | .PP |
3224 | Method 4: Do not use a prepare or check watcher because the module you |
3366 | Method 4: Do not use a prepare or check watcher because the module you |
3225 | want to embed is not flexible enough to support it. Instead, you can |
3367 | want to embed is not flexible enough to support it. Instead, you can |
3226 | override their poll function. The drawback with this solution is that the |
3368 | override their poll function. The drawback with this solution is that the |
3227 | main loop is now no longer controllable by \s-1EV\s0. The \f(CW\*(C`Glib::EV\*(C'\fR module uses |
3369 | main loop is now no longer controllable by \s-1EV.\s0 The \f(CW\*(C`Glib::EV\*(C'\fR module uses |
3228 | this approach, effectively embedding \s-1EV\s0 as a client into the horrible |
3370 | this approach, effectively embedding \s-1EV\s0 as a client into the horrible |
3229 | libglib event loop. |
3371 | libglib event loop. |
3230 | .PP |
3372 | .PP |
3231 | .Vb 4 |
3373 | .Vb 4 |
3232 | \& static gint |
3374 | \& static gint |
… | |
… | |
3316 | \fIWatcher-Specific Functions and Data Members\fR |
3458 | \fIWatcher-Specific Functions and Data Members\fR |
3317 | .IX Subsection "Watcher-Specific Functions and Data Members" |
3459 | .IX Subsection "Watcher-Specific Functions and Data Members" |
3318 | .IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
3460 | .IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
3319 | .IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" |
3461 | .IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" |
3320 | .PD 0 |
3462 | .PD 0 |
3321 | .IP "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
3463 | .IP "ev_embed_set (ev_embed *, struct ev_loop *embedded_loop)" 4 |
3322 | .IX Item "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" |
3464 | .IX Item "ev_embed_set (ev_embed *, struct ev_loop *embedded_loop)" |
3323 | .PD |
3465 | .PD |
3324 | Configures the watcher to embed the given loop, which must be |
3466 | Configures the watcher to embed the given loop, which must be |
3325 | embeddable. If the callback is \f(CW0\fR, then \f(CW\*(C`ev_embed_sweep\*(C'\fR will be |
3467 | embeddable. If the callback is \f(CW0\fR, then \f(CW\*(C`ev_embed_sweep\*(C'\fR will be |
3326 | invoked automatically, otherwise it is the responsibility of the callback |
3468 | invoked automatically, otherwise it is the responsibility of the callback |
3327 | to invoke it (it will continue to be called until the sweep has been done, |
3469 | to invoke it (it will continue to be called until the sweep has been done, |
… | |
… | |
3346 | .PP |
3488 | .PP |
3347 | .Vb 3 |
3489 | .Vb 3 |
3348 | \& struct ev_loop *loop_hi = ev_default_init (0); |
3490 | \& struct ev_loop *loop_hi = ev_default_init (0); |
3349 | \& struct ev_loop *loop_lo = 0; |
3491 | \& struct ev_loop *loop_lo = 0; |
3350 | \& ev_embed embed; |
3492 | \& ev_embed embed; |
3351 | \& |
3493 | \& |
3352 | \& // see if there is a chance of getting one that works |
3494 | \& // see if there is a chance of getting one that works |
3353 | \& // (remember that a flags value of 0 means autodetection) |
3495 | \& // (remember that a flags value of 0 means autodetection) |
3354 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3496 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3355 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3497 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3356 | \& : 0; |
3498 | \& : 0; |
… | |
… | |
3372 | .PP |
3514 | .PP |
3373 | .Vb 3 |
3515 | .Vb 3 |
3374 | \& struct ev_loop *loop = ev_default_init (0); |
3516 | \& struct ev_loop *loop = ev_default_init (0); |
3375 | \& struct ev_loop *loop_socket = 0; |
3517 | \& struct ev_loop *loop_socket = 0; |
3376 | \& ev_embed embed; |
3518 | \& ev_embed embed; |
3377 | \& |
3519 | \& |
3378 | \& if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3520 | \& if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3379 | \& if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3521 | \& if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3380 | \& { |
3522 | \& { |
3381 | \& ev_embed_init (&embed, 0, loop_socket); |
3523 | \& ev_embed_init (&embed, 0, loop_socket); |
3382 | \& ev_embed_start (loop, &embed); |
3524 | \& ev_embed_start (loop, &embed); |
… | |
… | |
3399 | of course. |
3541 | of course. |
3400 | .PP |
3542 | .PP |
3401 | \fIThe special problem of life after fork \- how is it possible?\fR |
3543 | \fIThe special problem of life after fork \- how is it possible?\fR |
3402 | .IX Subsection "The special problem of life after fork - how is it possible?" |
3544 | .IX Subsection "The special problem of life after fork - how is it possible?" |
3403 | .PP |
3545 | .PP |
3404 | Most uses of \f(CW\*(C`fork()\*(C'\fR consist of forking, then some simple calls to set |
3546 | Most uses of \f(CW\*(C`fork ()\*(C'\fR consist of forking, then some simple calls to set |
3405 | up/change the process environment, followed by a call to \f(CW\*(C`exec()\*(C'\fR. This |
3547 | up/change the process environment, followed by a call to \f(CW\*(C`exec()\*(C'\fR. This |
3406 | sequence should be handled by libev without any problems. |
3548 | sequence should be handled by libev without any problems. |
3407 | .PP |
3549 | .PP |
3408 | This changes when the application actually wants to do event handling |
3550 | This changes when the application actually wants to do event handling |
3409 | in the child, or both parent in child, in effect \*(L"continuing\*(R" after the |
3551 | in the child, or both parent in child, in effect \*(L"continuing\*(R" after the |
… | |
… | |
3626 | is a time window between the event loop checking and resetting the async |
3768 | is a time window between the event loop checking and resetting the async |
3627 | notification, and the callback being invoked. |
3769 | notification, and the callback being invoked. |
3628 | .SH "OTHER FUNCTIONS" |
3770 | .SH "OTHER FUNCTIONS" |
3629 | .IX Header "OTHER FUNCTIONS" |
3771 | .IX Header "OTHER FUNCTIONS" |
3630 | There are some other functions of possible interest. Described. Here. Now. |
3772 | There are some other functions of possible interest. Described. Here. Now. |
3631 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 |
3773 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback, arg)" 4 |
3632 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" |
3774 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback, arg)" |
3633 | This function combines a simple timer and an I/O watcher, calls your |
3775 | This function combines a simple timer and an I/O watcher, calls your |
3634 | callback on whichever event happens first and automatically stops both |
3776 | callback on whichever event happens first and automatically stops both |
3635 | watchers. This is useful if you want to wait for a single event on an fd |
3777 | watchers. This is useful if you want to wait for a single event on an fd |
3636 | or timeout without having to allocate/configure/start/stop/free one or |
3778 | or timeout without having to allocate/configure/start/stop/free one or |
3637 | more watchers yourself. |
3779 | more watchers yourself. |
… | |
… | |
3649 | \&\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 |
3791 | \&\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 |
3650 | value passed to \f(CW\*(C`ev_once\*(C'\fR. Note that it is possible to receive \fIboth\fR |
3792 | value passed to \f(CW\*(C`ev_once\*(C'\fR. Note that it is possible to receive \fIboth\fR |
3651 | a timeout and an io event at the same time \- you probably should give io |
3793 | a timeout and an io event at the same time \- you probably should give io |
3652 | events precedence. |
3794 | events precedence. |
3653 | .Sp |
3795 | .Sp |
3654 | Example: wait up to ten seconds for data to appear on \s-1STDIN_FILENO\s0. |
3796 | Example: wait up to ten seconds for data to appear on \s-1STDIN_FILENO.\s0 |
3655 | .Sp |
3797 | .Sp |
3656 | .Vb 7 |
3798 | .Vb 7 |
3657 | \& static void stdin_ready (int revents, void *arg) |
3799 | \& static void stdin_ready (int revents, void *arg) |
3658 | \& { |
3800 | \& { |
3659 | \& if (revents & EV_READ) |
3801 | \& if (revents & EV_READ) |
… | |
… | |
3675 | .SH "COMMON OR USEFUL IDIOMS (OR BOTH)" |
3817 | .SH "COMMON OR USEFUL IDIOMS (OR BOTH)" |
3676 | .IX Header "COMMON OR USEFUL IDIOMS (OR BOTH)" |
3818 | .IX Header "COMMON OR USEFUL IDIOMS (OR BOTH)" |
3677 | This section explains some common idioms that are not immediately |
3819 | This section explains some common idioms that are not immediately |
3678 | obvious. Note that examples are sprinkled over the whole manual, and this |
3820 | obvious. Note that examples are sprinkled over the whole manual, and this |
3679 | section only contains stuff that wouldn't fit anywhere else. |
3821 | section only contains stuff that wouldn't fit anywhere else. |
3680 | .SS "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" |
3822 | .SS "\s-1ASSOCIATING CUSTOM DATA WITH A WATCHER\s0" |
3681 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
3823 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
3682 | Each watcher has, by default, a \f(CW\*(C`void *data\*(C'\fR member that you can read |
3824 | Each watcher has, by default, a \f(CW\*(C`void *data\*(C'\fR member that you can read |
3683 | or modify at any time: libev will completely ignore it. This can be used |
3825 | or modify at any time: libev will completely ignore it. This can be used |
3684 | to associate arbitrary data with your watcher. If you need more data and |
3826 | to associate arbitrary data with your watcher. If you need more data and |
3685 | don't want to allocate memory separately and store a pointer to it in that |
3827 | don't want to allocate memory separately and store a pointer to it in that |
… | |
… | |
3711 | \& } |
3853 | \& } |
3712 | .Ve |
3854 | .Ve |
3713 | .PP |
3855 | .PP |
3714 | More interesting and less C\-conformant ways of casting your callback |
3856 | More interesting and less C\-conformant ways of casting your callback |
3715 | function type instead have been omitted. |
3857 | function type instead have been omitted. |
3716 | .SS "\s-1BUILDING\s0 \s-1YOUR\s0 \s-1OWN\s0 \s-1COMPOSITE\s0 \s-1WATCHERS\s0" |
3858 | .SS "\s-1BUILDING YOUR OWN COMPOSITE WATCHERS\s0" |
3717 | .IX Subsection "BUILDING YOUR OWN COMPOSITE WATCHERS" |
3859 | .IX Subsection "BUILDING YOUR OWN COMPOSITE WATCHERS" |
3718 | Another common scenario is to use some data structure with multiple |
3860 | Another common scenario is to use some data structure with multiple |
3719 | embedded watchers, in effect creating your own watcher that combines |
3861 | embedded watchers, in effect creating your own watcher that combines |
3720 | multiple libev event sources into one \*(L"super-watcher\*(R": |
3862 | multiple libev event sources into one \*(L"super-watcher\*(R": |
3721 | .PP |
3863 | .PP |
… | |
… | |
3749 | \& { |
3891 | \& { |
3750 | \& struct my_biggy big = (struct my_biggy *) |
3892 | \& struct my_biggy big = (struct my_biggy *) |
3751 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
3893 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
3752 | \& } |
3894 | \& } |
3753 | .Ve |
3895 | .Ve |
3754 | .SS "\s-1AVOIDING\s0 \s-1FINISHING\s0 \s-1BEFORE\s0 \s-1RETURNING\s0" |
3896 | .SS "\s-1AVOIDING FINISHING BEFORE RETURNING\s0" |
3755 | .IX Subsection "AVOIDING FINISHING BEFORE RETURNING" |
3897 | .IX Subsection "AVOIDING FINISHING BEFORE RETURNING" |
3756 | Often you have structures like this in event-based programs: |
3898 | Often you have structures like this in event-based programs: |
3757 | .PP |
3899 | .PP |
3758 | .Vb 4 |
3900 | .Vb 4 |
3759 | \& callback () |
3901 | \& callback () |
… | |
… | |
3781 | already been invoked. |
3923 | already been invoked. |
3782 | .PP |
3924 | .PP |
3783 | A common way around all these issues is to make sure that |
3925 | A common way around all these issues is to make sure that |
3784 | \&\f(CW\*(C`start_new_request\*(C'\fR \fIalways\fR returns before the callback is invoked. If |
3926 | \&\f(CW\*(C`start_new_request\*(C'\fR \fIalways\fR returns before the callback is invoked. If |
3785 | \&\f(CW\*(C`start_new_request\*(C'\fR immediately knows the result, it can artificially |
3927 | \&\f(CW\*(C`start_new_request\*(C'\fR immediately knows the result, it can artificially |
3786 | delay invoking the callback by e.g. using a \f(CW\*(C`prepare\*(C'\fR or \f(CW\*(C`idle\*(C'\fR watcher |
3928 | delay invoking the callback by using a \f(CW\*(C`prepare\*(C'\fR or \f(CW\*(C`idle\*(C'\fR watcher for |
3787 | for example, or more sneakily, by reusing an existing (stopped) watcher |
3929 | example, or more sneakily, by reusing an existing (stopped) watcher and |
3788 | and pushing it into the pending queue: |
3930 | pushing it into the pending queue: |
3789 | .PP |
3931 | .PP |
3790 | .Vb 2 |
3932 | .Vb 2 |
3791 | \& ev_set_cb (watcher, callback); |
3933 | \& ev_set_cb (watcher, callback); |
3792 | \& ev_feed_event (EV_A_ watcher, 0); |
3934 | \& ev_feed_event (EV_A_ watcher, 0); |
3793 | .Ve |
3935 | .Ve |
3794 | .PP |
3936 | .PP |
3795 | This way, \f(CW\*(C`start_new_request\*(C'\fR can safely return before the callback is |
3937 | This way, \f(CW\*(C`start_new_request\*(C'\fR can safely return before the callback is |
3796 | invoked, while not delaying callback invocation too much. |
3938 | invoked, while not delaying callback invocation too much. |
3797 | .SS "\s-1MODEL/NESTED\s0 \s-1EVENT\s0 \s-1LOOP\s0 \s-1INVOCATIONS\s0 \s-1AND\s0 \s-1EXIT\s0 \s-1CONDITIONS\s0" |
3939 | .SS "\s-1MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS\s0" |
3798 | .IX Subsection "MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS" |
3940 | .IX Subsection "MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS" |
3799 | Often (especially in \s-1GUI\s0 toolkits) there are places where you have |
3941 | Often (especially in \s-1GUI\s0 toolkits) there are places where you have |
3800 | \&\fImodal\fR interaction, which is most easily implemented by recursively |
3942 | \&\fImodal\fR interaction, which is most easily implemented by recursively |
3801 | invoking \f(CW\*(C`ev_run\*(C'\fR. |
3943 | invoking \f(CW\*(C`ev_run\*(C'\fR. |
3802 | .PP |
3944 | .PP |
3803 | This brings the problem of exiting \- a callback might want to finish the |
3945 | This brings the problem of exiting \- a callback might want to finish the |
3804 | main \f(CW\*(C`ev_run\*(C'\fR call, but not the nested one (e.g. user clicked \*(L"Quit\*(R", but |
3946 | main \f(CW\*(C`ev_run\*(C'\fR call, but not the nested one (e.g. user clicked \*(L"Quit\*(R", but |
3805 | a modal \*(L"Are you sure?\*(R" dialog is still waiting), or just the nested one |
3947 | a modal \*(L"Are you sure?\*(R" dialog is still waiting), or just the nested one |
3806 | and not the main one (e.g. user clocked \*(L"Ok\*(R" in a modal dialog), or some |
3948 | and not the main one (e.g. user clocked \*(L"Ok\*(R" in a modal dialog), or some |
3807 | other combination: In these cases, \f(CW\*(C`ev_break\*(C'\fR will not work alone. |
3949 | other combination: In these cases, a simple \f(CW\*(C`ev_break\*(C'\fR will not work. |
3808 | .PP |
3950 | .PP |
3809 | The solution is to maintain \*(L"break this loop\*(R" variable for each \f(CW\*(C`ev_run\*(C'\fR |
3951 | The solution is to maintain \*(L"break this loop\*(R" variable for each \f(CW\*(C`ev_run\*(C'\fR |
3810 | invocation, and use a loop around \f(CW\*(C`ev_run\*(C'\fR until the condition is |
3952 | invocation, and use a loop around \f(CW\*(C`ev_run\*(C'\fR until the condition is |
3811 | triggered, using \f(CW\*(C`EVRUN_ONCE\*(C'\fR: |
3953 | triggered, using \f(CW\*(C`EVRUN_ONCE\*(C'\fR: |
3812 | .PP |
3954 | .PP |
… | |
… | |
3834 | \& exit_main_loop = 1; |
3976 | \& exit_main_loop = 1; |
3835 | \& |
3977 | \& |
3836 | \& // exit both |
3978 | \& // exit both |
3837 | \& exit_main_loop = exit_nested_loop = 1; |
3979 | \& exit_main_loop = exit_nested_loop = 1; |
3838 | .Ve |
3980 | .Ve |
3839 | .SS "\s-1THREAD\s0 \s-1LOCKING\s0 \s-1EXAMPLE\s0" |
3981 | .SS "\s-1THREAD LOCKING EXAMPLE\s0" |
3840 | .IX Subsection "THREAD LOCKING EXAMPLE" |
3982 | .IX Subsection "THREAD LOCKING EXAMPLE" |
3841 | Here is a fictitious example of how to run an event loop in a different |
3983 | Here is a fictitious example of how to run an event loop in a different |
3842 | thread from where callbacks are being invoked and watchers are |
3984 | thread from where callbacks are being invoked and watchers are |
3843 | created/added/removed. |
3985 | created/added/removed. |
3844 | .PP |
3986 | .PP |
… | |
… | |
3985 | .PP |
4127 | .PP |
3986 | Note that sending the \f(CW\*(C`ev_async\*(C'\fR watcher is required because otherwise |
4128 | Note that sending the \f(CW\*(C`ev_async\*(C'\fR watcher is required because otherwise |
3987 | an event loop currently blocking in the kernel will have no knowledge |
4129 | an event loop currently blocking in the kernel will have no knowledge |
3988 | about the newly added timer. By waking up the loop it will pick up any new |
4130 | about the newly added timer. By waking up the loop it will pick up any new |
3989 | watchers in the next event loop iteration. |
4131 | watchers in the next event loop iteration. |
3990 | .SS "\s-1THREADS\s0, \s-1COROUTINES\s0, \s-1CONTINUATIONS\s0, \s-1QUEUES\s0... \s-1INSTEAD\s0 \s-1OF\s0 \s-1CALLBACKS\s0" |
4132 | .SS "\s-1THREADS, COROUTINES, CONTINUATIONS, QUEUES... INSTEAD OF CALLBACKS\s0" |
3991 | .IX Subsection "THREADS, COROUTINES, CONTINUATIONS, QUEUES... INSTEAD OF CALLBACKS" |
4133 | .IX Subsection "THREADS, COROUTINES, CONTINUATIONS, QUEUES... INSTEAD OF CALLBACKS" |
3992 | While the overhead of a callback that e.g. schedules a thread is small, it |
4134 | While the overhead of a callback that e.g. schedules a thread is small, it |
3993 | is still an overhead. If you embed libev, and your main usage is with some |
4135 | is still an overhead. If you embed libev, and your main usage is with some |
3994 | kind of threads or coroutines, you might want to customise libev so that |
4136 | kind of threads or coroutines, you might want to customise libev so that |
3995 | doesn't need callbacks anymore. |
4137 | doesn't need callbacks anymore. |
… | |
… | |
4031 | You can do similar tricks if you have, say, threads with an event queue \- |
4173 | You can do similar tricks if you have, say, threads with an event queue \- |
4032 | instead of storing a coroutine, you store the queue object and instead of |
4174 | instead of storing a coroutine, you store the queue object and instead of |
4033 | switching to a coroutine, you push the watcher onto the queue and notify |
4175 | switching to a coroutine, you push the watcher onto the queue and notify |
4034 | any waiters. |
4176 | any waiters. |
4035 | .PP |
4177 | .PP |
4036 | To embed libev, see \*(L"\s-1EMBEDDING\s0\*(R", but in short, it's easiest to create two |
4178 | To embed libev, see \*(L"\s-1EMBEDDING\*(R"\s0, but in short, it's easiest to create two |
4037 | files, \fImy_ev.h\fR and \fImy_ev.c\fR that include the respective libev files: |
4179 | files, \fImy_ev.h\fR and \fImy_ev.c\fR that include the respective libev files: |
4038 | .PP |
4180 | .PP |
4039 | .Vb 4 |
4181 | .Vb 4 |
4040 | \& // my_ev.h |
4182 | \& // my_ev.h |
4041 | \& #define EV_CB_DECLARE(type) struct my_coro *cb; |
4183 | \& #define EV_CB_DECLARE(type) struct my_coro *cb; |
4042 | \& #define EV_CB_INVOKE(watcher) switch_to ((watcher)\->cb); |
4184 | \& #define EV_CB_INVOKE(watcher) switch_to ((watcher)\->cb) |
4043 | \& #include "../libev/ev.h" |
4185 | \& #include "../libev/ev.h" |
4044 | \& |
4186 | \& |
4045 | \& // my_ev.c |
4187 | \& // my_ev.c |
4046 | \& #define EV_H "my_ev.h" |
4188 | \& #define EV_H "my_ev.h" |
4047 | \& #include "../libev/ev.c" |
4189 | \& #include "../libev/ev.c" |
… | |
… | |
4087 | The normal C \s-1API\s0 should work fine when used from \*(C+: both ev.h and the |
4229 | The normal C \s-1API\s0 should work fine when used from \*(C+: both ev.h and the |
4088 | libev sources can be compiled as \*(C+. Therefore, code that uses the C \s-1API\s0 |
4230 | libev sources can be compiled as \*(C+. Therefore, code that uses the C \s-1API\s0 |
4089 | will work fine. |
4231 | will work fine. |
4090 | .PP |
4232 | .PP |
4091 | Proper exception specifications might have to be added to callbacks passed |
4233 | Proper exception specifications might have to be added to callbacks passed |
4092 | to libev: exceptions may be thrown only from watcher callbacks, all |
4234 | to libev: exceptions may be thrown only from watcher callbacks, all other |
4093 | other callbacks (allocator, syserr, loop acquire/release and periodic |
4235 | callbacks (allocator, syserr, loop acquire/release and periodic reschedule |
4094 | reschedule callbacks) must not throw exceptions, and might need a \f(CW\*(C`throw |
4236 | callbacks) must not throw exceptions, and might need a \f(CW\*(C`noexcept\*(C'\fR |
4095 | ()\*(C'\fR specification. If you have code that needs to be compiled as both C |
4237 | specification. If you have code that needs to be compiled as both C and |
4096 | and \*(C+ you can use the \f(CW\*(C`EV_THROW\*(C'\fR macro for this: |
4238 | \&\*(C+ you can use the \f(CW\*(C`EV_NOEXCEPT\*(C'\fR macro for this: |
4097 | .PP |
4239 | .PP |
4098 | .Vb 6 |
4240 | .Vb 6 |
4099 | \& static void |
4241 | \& static void |
4100 | \& fatal_error (const char *msg) EV_THROW |
4242 | \& fatal_error (const char *msg) EV_NOEXCEPT |
4101 | \& { |
4243 | \& { |
4102 | \& perror (msg); |
4244 | \& perror (msg); |
4103 | \& abort (); |
4245 | \& abort (); |
4104 | \& } |
4246 | \& } |
4105 | \& |
4247 | \& |
… | |
… | |
4233 | \& void operator() (ev::io &w, int revents) |
4375 | \& void operator() (ev::io &w, int revents) |
4234 | \& { |
4376 | \& { |
4235 | \& ... |
4377 | \& ... |
4236 | \& } |
4378 | \& } |
4237 | \& } |
4379 | \& } |
4238 | \& |
4380 | \& |
4239 | \& myfunctor f; |
4381 | \& myfunctor f; |
4240 | \& |
4382 | \& |
4241 | \& ev::io w; |
4383 | \& ev::io w; |
4242 | \& w.set (&f); |
4384 | \& w.set (&f); |
4243 | .Ve |
4385 | .Ve |
… | |
… | |
4336 | there are additional modules that implement libev-compatible interfaces |
4478 | there are additional modules that implement libev-compatible interfaces |
4337 | 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), |
4479 | 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), |
4338 | \&\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 |
4480 | \&\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 |
4339 | and \f(CW\*(C`EV::Glib\*(C'\fR). |
4481 | and \f(CW\*(C`EV::Glib\*(C'\fR). |
4340 | .Sp |
4482 | .Sp |
4341 | It can be found and installed via \s-1CPAN\s0, its homepage is at |
4483 | It can be found and installed via \s-1CPAN,\s0 its homepage is at |
4342 | <http://software.schmorp.de/pkg/EV>. |
4484 | <http://software.schmorp.de/pkg/EV>. |
4343 | .IP "Python" 4 |
4485 | .IP "Python" 4 |
4344 | .IX Item "Python" |
4486 | .IX Item "Python" |
4345 | Python bindings can be found at <http://code.google.com/p/pyev/>. It |
4487 | Python bindings can be found at <http://code.google.com/p/pyev/>. It |
4346 | seems to be quite complete and well-documented. |
4488 | seems to be quite complete and well-documented. |
… | |
… | |
4354 | Roger Pack reports that using the link order \f(CW\*(C`\-lws2_32 \-lmsvcrt\-ruby\-190\*(C'\fR |
4496 | Roger Pack reports that using the link order \f(CW\*(C`\-lws2_32 \-lmsvcrt\-ruby\-190\*(C'\fR |
4355 | makes rev work even on mingw. |
4497 | makes rev work even on mingw. |
4356 | .IP "Haskell" 4 |
4498 | .IP "Haskell" 4 |
4357 | .IX Item "Haskell" |
4499 | .IX Item "Haskell" |
4358 | A haskell binding to libev is available at |
4500 | A haskell binding to libev is available at |
4359 | http://hackage.haskell.org/cgi\-bin/hackage\-scripts/package/hlibev <http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hlibev>. |
4501 | <http://hackage.haskell.org/cgi\-bin/hackage\-scripts/package/hlibev>. |
4360 | .IP "D" 4 |
4502 | .IP "D" 4 |
4361 | .IX Item "D" |
4503 | .IX Item "D" |
4362 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
4504 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
4363 | be found at <http://www.llucax.com.ar/proj/ev.d/index.html>. |
4505 | be found at <http://www.llucax.com.ar/proj/ev.d/index.html>. |
4364 | .IP "Ocaml" 4 |
4506 | .IP "Ocaml" 4 |
4365 | .IX Item "Ocaml" |
4507 | .IX Item "Ocaml" |
4366 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
4508 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
4367 | http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/ <http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
4509 | <http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/>. |
4368 | .IP "Lua" 4 |
4510 | .IP "Lua" 4 |
4369 | .IX Item "Lua" |
4511 | .IX Item "Lua" |
4370 | Brian Maher has written a partial interface to libev for lua (at the |
4512 | Brian Maher has written a partial interface to libev for lua (at the |
4371 | time of this writing, only \f(CW\*(C`ev_io\*(C'\fR and \f(CW\*(C`ev_timer\*(C'\fR), to be found at |
4513 | time of this writing, only \f(CW\*(C`ev_io\*(C'\fR and \f(CW\*(C`ev_timer\*(C'\fR), to be found at |
4372 | http://github.com/brimworks/lua\-ev <http://github.com/brimworks/lua-ev>. |
4514 | <http://github.com/brimworks/lua\-ev>. |
4373 | .IP "Javascript" 4 |
4515 | .IP "Javascript" 4 |
4374 | .IX Item "Javascript" |
4516 | .IX Item "Javascript" |
4375 | Node.js (<http://nodejs.org>) uses libev as the underlying event library. |
4517 | Node.js (<http://nodejs.org>) uses libev as the underlying event library. |
4376 | .IP "Others" 4 |
4518 | .IP "Others" 4 |
4377 | .IX Item "Others" |
4519 | .IX Item "Others" |
… | |
… | |
4466 | .SS "\s-1FILESETS\s0" |
4608 | .SS "\s-1FILESETS\s0" |
4467 | .IX Subsection "FILESETS" |
4609 | .IX Subsection "FILESETS" |
4468 | Depending on what features you need you need to include one or more sets of files |
4610 | Depending on what features you need you need to include one or more sets of files |
4469 | in your application. |
4611 | in your application. |
4470 | .PP |
4612 | .PP |
4471 | \fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR |
4613 | \fI\s-1CORE EVENT LOOP\s0\fR |
4472 | .IX Subsection "CORE EVENT LOOP" |
4614 | .IX Subsection "CORE EVENT LOOP" |
4473 | .PP |
4615 | .PP |
4474 | To include only the libev core (all the \f(CW\*(C`ev_*\*(C'\fR functions), with manual |
4616 | To include only the libev core (all the \f(CW\*(C`ev_*\*(C'\fR functions), with manual |
4475 | configuration (no autoconf): |
4617 | configuration (no autoconf): |
4476 | .PP |
4618 | .PP |
… | |
… | |
4503 | \& ev_vars.h |
4645 | \& ev_vars.h |
4504 | \& ev_wrap.h |
4646 | \& ev_wrap.h |
4505 | \& |
4647 | \& |
4506 | \& ev_win32.c required on win32 platforms only |
4648 | \& ev_win32.c required on win32 platforms only |
4507 | \& |
4649 | \& |
4508 | \& ev_select.c only when select backend is enabled (which is enabled by default) |
4650 | \& ev_select.c only when select backend is enabled |
4509 | \& ev_poll.c only when poll backend is enabled (disabled by default) |
4651 | \& ev_poll.c only when poll backend is enabled |
4510 | \& ev_epoll.c only when the epoll backend is enabled (disabled by default) |
4652 | \& ev_epoll.c only when the epoll backend is enabled |
|
|
4653 | \& ev_linuxaio.c only when the linux aio backend is enabled |
|
|
4654 | \& ev_iouring.c only when the linux io_uring backend is enabled |
4511 | \& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
4655 | \& ev_kqueue.c only when the kqueue backend is enabled |
4512 | \& ev_port.c only when the solaris port backend is enabled (disabled by default) |
4656 | \& ev_port.c only when the solaris port backend is enabled |
4513 | .Ve |
4657 | .Ve |
4514 | .PP |
4658 | .PP |
4515 | \&\fIev.c\fR includes the backend files directly when enabled, so you only need |
4659 | \&\fIev.c\fR includes the backend files directly when enabled, so you only need |
4516 | to compile this single file. |
4660 | to compile this single file. |
4517 | .PP |
4661 | .PP |
4518 | \fI\s-1LIBEVENT\s0 \s-1COMPATIBILITY\s0 \s-1API\s0\fR |
4662 | \fI\s-1LIBEVENT COMPATIBILITY API\s0\fR |
4519 | .IX Subsection "LIBEVENT COMPATIBILITY API" |
4663 | .IX Subsection "LIBEVENT COMPATIBILITY API" |
4520 | .PP |
4664 | .PP |
4521 | To include the libevent compatibility \s-1API\s0, also include: |
4665 | To include the libevent compatibility \s-1API,\s0 also include: |
4522 | .PP |
4666 | .PP |
4523 | .Vb 1 |
4667 | .Vb 1 |
4524 | \& #include "event.c" |
4668 | \& #include "event.c" |
4525 | .Ve |
4669 | .Ve |
4526 | .PP |
4670 | .PP |
… | |
… | |
4528 | .PP |
4672 | .PP |
4529 | .Vb 1 |
4673 | .Vb 1 |
4530 | \& #include "event.h" |
4674 | \& #include "event.h" |
4531 | .Ve |
4675 | .Ve |
4532 | .PP |
4676 | .PP |
4533 | in the files that want to use the libevent \s-1API\s0. This also includes \fIev.h\fR. |
4677 | in the files that want to use the libevent \s-1API.\s0 This also includes \fIev.h\fR. |
4534 | .PP |
4678 | .PP |
4535 | You need the following additional files for this: |
4679 | You need the following additional files for this: |
4536 | .PP |
4680 | .PP |
4537 | .Vb 2 |
4681 | .Vb 2 |
4538 | \& event.h |
4682 | \& event.h |
4539 | \& event.c |
4683 | \& event.c |
4540 | .Ve |
4684 | .Ve |
4541 | .PP |
4685 | .PP |
4542 | \fI\s-1AUTOCONF\s0 \s-1SUPPORT\s0\fR |
4686 | \fI\s-1AUTOCONF SUPPORT\s0\fR |
4543 | .IX Subsection "AUTOCONF SUPPORT" |
4687 | .IX Subsection "AUTOCONF SUPPORT" |
4544 | .PP |
4688 | .PP |
4545 | Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your configuration in |
4689 | Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your configuration in |
4546 | whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your |
4690 | whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your |
4547 | \&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then |
4691 | \&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then |
… | |
… | |
4550 | For this of course you need the m4 file: |
4694 | For this of course you need the m4 file: |
4551 | .PP |
4695 | .PP |
4552 | .Vb 1 |
4696 | .Vb 1 |
4553 | \& libev.m4 |
4697 | \& libev.m4 |
4554 | .Ve |
4698 | .Ve |
4555 | .SS "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" |
4699 | .SS "\s-1PREPROCESSOR SYMBOLS/MACROS\s0" |
4556 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
4700 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
4557 | Libev can be configured via a variety of preprocessor symbols you have to |
4701 | Libev can be configured via a variety of preprocessor symbols you have to |
4558 | define before including (or compiling) any of its files. The default in |
4702 | define before including (or compiling) any of its files. The default in |
4559 | the absence of autoconf is documented for every option. |
4703 | the absence of autoconf is documented for every option. |
4560 | .PP |
4704 | .PP |
4561 | Symbols marked with \*(L"(h)\*(R" do not change the \s-1ABI\s0, and can have different |
4705 | Symbols marked with \*(L"(h)\*(R" do not change the \s-1ABI,\s0 and can have different |
4562 | values when compiling libev vs. including \fIev.h\fR, so it is permissible |
4706 | values when compiling libev vs. including \fIev.h\fR, so it is permissible |
4563 | to redefine them before including \fIev.h\fR without breaking compatibility |
4707 | to redefine them before including \fIev.h\fR without breaking compatibility |
4564 | to a compiled library. All other symbols change the \s-1ABI\s0, which means all |
4708 | to a compiled library. All other symbols change the \s-1ABI,\s0 which means all |
4565 | users of libev and the libev code itself must be compiled with compatible |
4709 | users of libev and the libev code itself must be compiled with compatible |
4566 | settings. |
4710 | settings. |
4567 | .IP "\s-1EV_COMPAT3\s0 (h)" 4 |
4711 | .IP "\s-1EV_COMPAT3\s0 (h)" 4 |
4568 | .IX Item "EV_COMPAT3 (h)" |
4712 | .IX Item "EV_COMPAT3 (h)" |
4569 | Backwards compatibility is a major concern for libev. This is why this |
4713 | Backwards compatibility is a major concern for libev. This is why this |
… | |
… | |
4628 | higher, as it simplifies linking (no need for \f(CW\*(C`\-lrt\*(C'\fR). |
4772 | higher, as it simplifies linking (no need for \f(CW\*(C`\-lrt\*(C'\fR). |
4629 | .IP "\s-1EV_USE_NANOSLEEP\s0" 4 |
4773 | .IP "\s-1EV_USE_NANOSLEEP\s0" 4 |
4630 | .IX Item "EV_USE_NANOSLEEP" |
4774 | .IX Item "EV_USE_NANOSLEEP" |
4631 | If defined to be \f(CW1\fR, libev will assume that \f(CW\*(C`nanosleep ()\*(C'\fR is available |
4775 | If defined to be \f(CW1\fR, libev will assume that \f(CW\*(C`nanosleep ()\*(C'\fR is available |
4632 | and will use it for delays. Otherwise it will use \f(CW\*(C`select ()\*(C'\fR. |
4776 | and will use it for delays. Otherwise it will use \f(CW\*(C`select ()\*(C'\fR. |
|
|
4777 | .IP "\s-1EV_USE_EVENTFD\s0" 4 |
|
|
4778 | .IX Item "EV_USE_EVENTFD" |
|
|
4779 | If defined to be \f(CW1\fR, then libev will assume that \f(CW\*(C`eventfd ()\*(C'\fR is |
|
|
4780 | available and will probe for kernel support at runtime. This will improve |
|
|
4781 | \&\f(CW\*(C`ev_signal\*(C'\fR and \f(CW\*(C`ev_async\*(C'\fR performance and reduce resource consumption. |
|
|
4782 | If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc |
|
|
4783 | 2.7 or newer, otherwise disabled. |
|
|
4784 | .IP "\s-1EV_USE_SIGNALFD\s0" 4 |
|
|
4785 | .IX Item "EV_USE_SIGNALFD" |
|
|
4786 | If defined to be \f(CW1\fR, then libev will assume that \f(CW\*(C`signalfd ()\*(C'\fR is |
|
|
4787 | available and will probe for kernel support at runtime. This enables |
|
|
4788 | the use of \s-1EVFLAG_SIGNALFD\s0 for faster and simpler signal handling. If |
|
|
4789 | undefined, it will be enabled if the headers indicate GNU/Linux + Glibc |
|
|
4790 | 2.7 or newer, otherwise disabled. |
|
|
4791 | .IP "\s-1EV_USE_TIMERFD\s0" 4 |
|
|
4792 | .IX Item "EV_USE_TIMERFD" |
|
|
4793 | If defined to be \f(CW1\fR, then libev will assume that \f(CW\*(C`timerfd ()\*(C'\fR is |
|
|
4794 | available and will probe for kernel support at runtime. This allows |
|
|
4795 | libev to detect time jumps accurately. If undefined, it will be enabled |
|
|
4796 | if the headers indicate GNU/Linux + Glibc 2.8 or newer and define |
|
|
4797 | \&\f(CW\*(C`TFD_TIMER_CANCEL_ON_SET\*(C'\fR, otherwise disabled. |
4633 | .IP "\s-1EV_USE_EVENTFD\s0" 4 |
4798 | .IP "\s-1EV_USE_EVENTFD\s0" 4 |
4634 | .IX Item "EV_USE_EVENTFD" |
4799 | .IX Item "EV_USE_EVENTFD" |
4635 | If defined to be \f(CW1\fR, then libev will assume that \f(CW\*(C`eventfd ()\*(C'\fR is |
4800 | If defined to be \f(CW1\fR, then libev will assume that \f(CW\*(C`eventfd ()\*(C'\fR is |
4636 | available and will probe for kernel support at runtime. This will improve |
4801 | available and will probe for kernel support at runtime. This will improve |
4637 | \&\f(CW\*(C`ev_signal\*(C'\fR and \f(CW\*(C`ev_async\*(C'\fR performance and reduce resource consumption. |
4802 | \&\f(CW\*(C`ev_signal\*(C'\fR and \f(CW\*(C`ev_async\*(C'\fR performance and reduce resource consumption. |
… | |
… | |
4696 | If defined to be \f(CW1\fR, libev will compile in support for the Linux |
4861 | If defined to be \f(CW1\fR, libev will compile in support for the Linux |
4697 | \&\f(CW\*(C`epoll\*(C'\fR(7) backend. Its availability will be detected at runtime, |
4862 | \&\f(CW\*(C`epoll\*(C'\fR(7) backend. Its availability will be detected at runtime, |
4698 | otherwise another method will be used as fallback. This is the preferred |
4863 | otherwise another method will be used as fallback. This is the preferred |
4699 | backend for GNU/Linux systems. If undefined, it will be enabled if the |
4864 | backend for GNU/Linux systems. If undefined, it will be enabled if the |
4700 | headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
4865 | headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
|
|
4866 | .IP "\s-1EV_USE_LINUXAIO\s0" 4 |
|
|
4867 | .IX Item "EV_USE_LINUXAIO" |
|
|
4868 | If defined to be \f(CW1\fR, libev will compile in support for the Linux aio |
|
|
4869 | backend (\f(CW\*(C`EV_USE_EPOLL\*(C'\fR must also be enabled). If undefined, it will be |
|
|
4870 | enabled on linux, otherwise disabled. |
|
|
4871 | .IP "\s-1EV_USE_IOURING\s0" 4 |
|
|
4872 | .IX Item "EV_USE_IOURING" |
|
|
4873 | If defined to be \f(CW1\fR, libev will compile in support for the Linux |
|
|
4874 | io_uring backend (\f(CW\*(C`EV_USE_EPOLL\*(C'\fR must also be enabled). Due to it's |
|
|
4875 | current limitations it has to be requested explicitly. If undefined, it |
|
|
4876 | will be enabled on linux, otherwise disabled. |
4701 | .IP "\s-1EV_USE_KQUEUE\s0" 4 |
4877 | .IP "\s-1EV_USE_KQUEUE\s0" 4 |
4702 | .IX Item "EV_USE_KQUEUE" |
4878 | .IX Item "EV_USE_KQUEUE" |
4703 | If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style |
4879 | If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style |
4704 | \&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime, |
4880 | \&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime, |
4705 | otherwise another method will be used as fallback. This is the preferred |
4881 | otherwise another method will be used as fallback. This is the preferred |
… | |
… | |
4730 | between threads, that is, threads can be used, but threads never run on |
4906 | between threads, that is, threads can be used, but threads never run on |
4731 | different cpus (or different cpu cores). This reduces dependencies |
4907 | different cpus (or different cpu cores). This reduces dependencies |
4732 | and makes libev faster. |
4908 | and makes libev faster. |
4733 | .IP "\s-1EV_NO_THREADS\s0" 4 |
4909 | .IP "\s-1EV_NO_THREADS\s0" 4 |
4734 | .IX Item "EV_NO_THREADS" |
4910 | .IX Item "EV_NO_THREADS" |
4735 | If defined to be \f(CW1\fR, libev will assume that it will never be called |
4911 | If defined to be \f(CW1\fR, libev will assume that it will never be called from |
4736 | from different threads, which is a stronger assumption than \f(CW\*(C`EV_NO_SMP\*(C'\fR, |
4912 | different threads (that includes signal handlers), which is a stronger |
4737 | above. This reduces dependencies and makes libev faster. |
4913 | assumption than \f(CW\*(C`EV_NO_SMP\*(C'\fR, above. This reduces dependencies and makes |
|
|
4914 | libev faster. |
4738 | .IP "\s-1EV_ATOMIC_T\s0" 4 |
4915 | .IP "\s-1EV_ATOMIC_T\s0" 4 |
4739 | .IX Item "EV_ATOMIC_T" |
4916 | .IX Item "EV_ATOMIC_T" |
4740 | Libev requires an integer type (suitable for storing \f(CW0\fR or \f(CW1\fR) whose |
4917 | Libev requires an integer type (suitable for storing \f(CW0\fR or \f(CW1\fR) whose |
4741 | access is atomic with respect to other threads or signal contexts. No |
4918 | access is atomic with respect to other threads or signal contexts. No |
4742 | such type is easily found in the C language, so you can provide your own |
4919 | such type is easily found in the C language, so you can provide your own |
… | |
… | |
4792 | all the priorities, so having many of them (hundreds) uses a lot of space |
4969 | all the priorities, so having many of them (hundreds) uses a lot of space |
4793 | and time, so using the defaults of five priorities (\-2 .. +2) is usually |
4970 | and time, so using the defaults of five priorities (\-2 .. +2) is usually |
4794 | fine. |
4971 | fine. |
4795 | .Sp |
4972 | .Sp |
4796 | If your embedding application does not need any priorities, defining these |
4973 | If your embedding application does not need any priorities, defining these |
4797 | both to \f(CW0\fR will save some memory and \s-1CPU\s0. |
4974 | both to \f(CW0\fR will save some memory and \s-1CPU.\s0 |
4798 | .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 |
4975 | .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 |
4799 | .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." |
4976 | .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." |
4800 | If undefined or defined to be \f(CW1\fR (and the platform supports it), then |
4977 | If undefined or defined to be \f(CW1\fR (and the platform supports it), then |
4801 | the respective watcher type is supported. If defined to be \f(CW0\fR, then it |
4978 | the respective watcher type is supported. If defined to be \f(CW0\fR, then it |
4802 | is not. Disabling watcher types mainly saves code size. |
4979 | is not. Disabling watcher types mainly saves code size. |
4803 | .IP "\s-1EV_FEATURES\s0" 4 |
4980 | .IP "\s-1EV_FEATURES\s0" 4 |
… | |
… | |
4961 | called. If set to \f(CW2\fR, then the internal verification code will be |
5138 | called. If set to \f(CW2\fR, then the internal verification code will be |
4962 | called once per loop, which can slow down libev. If set to \f(CW3\fR, then the |
5139 | called once per loop, which can slow down libev. If set to \f(CW3\fR, then the |
4963 | verification code will be called very frequently, which will slow down |
5140 | verification code will be called very frequently, which will slow down |
4964 | libev considerably. |
5141 | libev considerably. |
4965 | .Sp |
5142 | .Sp |
|
|
5143 | Verification errors are reported via C's \f(CW\*(C`assert\*(C'\fR mechanism, so if you |
|
|
5144 | disable that (e.g. by defining \f(CW\*(C`NDEBUG\*(C'\fR) then no errors will be reported. |
|
|
5145 | .Sp |
4966 | The default is \f(CW1\fR, unless \f(CW\*(C`EV_FEATURES\*(C'\fR overrides it, in which case it |
5146 | The default is \f(CW1\fR, unless \f(CW\*(C`EV_FEATURES\*(C'\fR overrides it, in which case it |
4967 | will be \f(CW0\fR. |
5147 | will be \f(CW0\fR. |
4968 | .IP "\s-1EV_COMMON\s0" 4 |
5148 | .IP "\s-1EV_COMMON\s0" 4 |
4969 | .IX Item "EV_COMMON" |
5149 | .IX Item "EV_COMMON" |
4970 | By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining |
5150 | By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining |
… | |
… | |
4991 | and the way callbacks are invoked and set. Must expand to a struct member |
5171 | and the way callbacks are invoked and set. Must expand to a struct member |
4992 | definition and a statement, respectively. See the \fIev.h\fR header file for |
5172 | definition and a statement, respectively. See the \fIev.h\fR header file for |
4993 | their default definitions. One possible use for overriding these is to |
5173 | their default definitions. One possible use for overriding these is to |
4994 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
5174 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
4995 | method calls instead of plain function calls in \*(C+. |
5175 | method calls instead of plain function calls in \*(C+. |
4996 | .SS "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0" |
5176 | .SS "\s-1EXPORTED API SYMBOLS\s0" |
4997 | .IX Subsection "EXPORTED API SYMBOLS" |
5177 | .IX Subsection "EXPORTED API SYMBOLS" |
4998 | If you need to re-export the \s-1API\s0 (e.g. via a \s-1DLL\s0) and you need a list of |
5178 | If you need to re-export the \s-1API\s0 (e.g. via a \s-1DLL\s0) and you need a list of |
4999 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
5179 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
5000 | all public symbols, one per line: |
5180 | all public symbols, one per line: |
5001 | .PP |
5181 | .PP |
… | |
… | |
5055 | \& #include "ev_cpp.h" |
5235 | \& #include "ev_cpp.h" |
5056 | \& #include "ev.c" |
5236 | \& #include "ev.c" |
5057 | .Ve |
5237 | .Ve |
5058 | .SH "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT" |
5238 | .SH "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT" |
5059 | .IX Header "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT" |
5239 | .IX Header "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT" |
5060 | .SS "\s-1THREADS\s0 \s-1AND\s0 \s-1COROUTINES\s0" |
5240 | .SS "\s-1THREADS AND COROUTINES\s0" |
5061 | .IX Subsection "THREADS AND COROUTINES" |
5241 | .IX Subsection "THREADS AND COROUTINES" |
5062 | \fI\s-1THREADS\s0\fR |
5242 | \fI\s-1THREADS\s0\fR |
5063 | .IX Subsection "THREADS" |
5243 | .IX Subsection "THREADS" |
5064 | .PP |
5244 | .PP |
5065 | All libev functions are reentrant and thread-safe unless explicitly |
5245 | All libev functions are reentrant and thread-safe unless explicitly |
… | |
… | |
5111 | An example use would be to communicate signals or other events that only |
5291 | An example use would be to communicate signals or other events that only |
5112 | work in the default loop by registering the signal watcher with the |
5292 | work in the default loop by registering the signal watcher with the |
5113 | default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop |
5293 | default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop |
5114 | watcher callback into the event loop interested in the signal. |
5294 | watcher callback into the event loop interested in the signal. |
5115 | .PP |
5295 | .PP |
5116 | See also \*(L"\s-1THREAD\s0 \s-1LOCKING\s0 \s-1EXAMPLE\s0\*(R". |
5296 | See also \*(L"\s-1THREAD LOCKING EXAMPLE\*(R"\s0. |
5117 | .PP |
5297 | .PP |
5118 | \fI\s-1COROUTINES\s0\fR |
5298 | \fI\s-1COROUTINES\s0\fR |
5119 | .IX Subsection "COROUTINES" |
5299 | .IX Subsection "COROUTINES" |
5120 | .PP |
5300 | .PP |
5121 | Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"): |
5301 | Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"): |
… | |
… | |
5126 | that you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. |
5306 | that you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. |
5127 | .PP |
5307 | .PP |
5128 | Care has been taken to ensure that libev does not keep local state inside |
5308 | Care has been taken to ensure that libev does not keep local state inside |
5129 | \&\f(CW\*(C`ev_run\*(C'\fR, and other calls do not usually allow for coroutine switches as |
5309 | \&\f(CW\*(C`ev_run\*(C'\fR, and other calls do not usually allow for coroutine switches as |
5130 | they do not call any callbacks. |
5310 | they do not call any callbacks. |
5131 | .SS "\s-1COMPILER\s0 \s-1WARNINGS\s0" |
5311 | .SS "\s-1COMPILER WARNINGS\s0" |
5132 | .IX Subsection "COMPILER WARNINGS" |
5312 | .IX Subsection "COMPILER WARNINGS" |
5133 | Depending on your compiler and compiler settings, you might get no or a |
5313 | Depending on your compiler and compiler settings, you might get no or a |
5134 | lot of warnings when compiling libev code. Some people are apparently |
5314 | lot of warnings when compiling libev code. Some people are apparently |
5135 | scared by this. |
5315 | scared by this. |
5136 | .PP |
5316 | .PP |
… | |
… | |
5188 | .PP |
5368 | .PP |
5189 | If you need, for some reason, empty reports from valgrind for your project |
5369 | If you need, for some reason, empty reports from valgrind for your project |
5190 | I suggest using suppression lists. |
5370 | I suggest using suppression lists. |
5191 | .SH "PORTABILITY NOTES" |
5371 | .SH "PORTABILITY NOTES" |
5192 | .IX Header "PORTABILITY NOTES" |
5372 | .IX Header "PORTABILITY NOTES" |
5193 | .SS "\s-1GNU/LINUX\s0 32 \s-1BIT\s0 \s-1LIMITATIONS\s0" |
5373 | .SS "\s-1GNU/LINUX 32 BIT LIMITATIONS\s0" |
5194 | .IX Subsection "GNU/LINUX 32 BIT LIMITATIONS" |
5374 | .IX Subsection "GNU/LINUX 32 BIT LIMITATIONS" |
5195 | GNU/Linux is the only common platform that supports 64 bit file/large file |
5375 | GNU/Linux is the only common platform that supports 64 bit file/large file |
5196 | interfaces but \fIdisables\fR them by default. |
5376 | interfaces but \fIdisables\fR them by default. |
5197 | .PP |
5377 | .PP |
5198 | That means that libev compiled in the default environment doesn't support |
5378 | That means that libev compiled in the default environment doesn't support |
5199 | files larger than 2GiB or so, which mainly affects \f(CW\*(C`ev_stat\*(C'\fR watchers. |
5379 | files larger than 2GiB or so, which mainly affects \f(CW\*(C`ev_stat\*(C'\fR watchers. |
5200 | .PP |
5380 | .PP |
5201 | Unfortunately, many programs try to work around this GNU/Linux issue |
5381 | Unfortunately, many programs try to work around this GNU/Linux issue |
5202 | by enabling the large file \s-1API\s0, which makes them incompatible with the |
5382 | by enabling the large file \s-1API,\s0 which makes them incompatible with the |
5203 | standard libev compiled for their system. |
5383 | standard libev compiled for their system. |
5204 | .PP |
5384 | .PP |
5205 | Likewise, libev cannot enable the large file \s-1API\s0 itself as this would |
5385 | Likewise, libev cannot enable the large file \s-1API\s0 itself as this would |
5206 | suddenly make it incompatible to the default compile time environment, |
5386 | suddenly make it incompatible to the default compile time environment, |
5207 | i.e. all programs not using special compile switches. |
5387 | i.e. all programs not using special compile switches. |
5208 | .SS "\s-1OS/X\s0 \s-1AND\s0 \s-1DARWIN\s0 \s-1BUGS\s0" |
5388 | .SS "\s-1OS/X AND DARWIN BUGS\s0" |
5209 | .IX Subsection "OS/X AND DARWIN BUGS" |
5389 | .IX Subsection "OS/X AND DARWIN BUGS" |
5210 | The whole thing is a bug if you ask me \- basically any system interface |
5390 | The whole thing is a bug if you ask me \- basically any system interface |
5211 | you touch is broken, whether it is locales, poll, kqueue or even the |
5391 | you touch is broken, whether it is locales, poll, kqueue or even the |
5212 | OpenGL drivers. |
5392 | OpenGL drivers. |
5213 | .PP |
5393 | .PP |
… | |
… | |
5235 | .PP |
5415 | .PP |
5236 | \fI\f(CI\*(C`select\*(C'\fI is buggy\fR |
5416 | \fI\f(CI\*(C`select\*(C'\fI is buggy\fR |
5237 | .IX Subsection "select is buggy" |
5417 | .IX Subsection "select is buggy" |
5238 | .PP |
5418 | .PP |
5239 | All that's left is \f(CW\*(C`select\*(C'\fR, and of course Apple found a way to fuck this |
5419 | All that's left is \f(CW\*(C`select\*(C'\fR, and of course Apple found a way to fuck this |
5240 | one up as well: On \s-1OS/X\s0, \f(CW\*(C`select\*(C'\fR actively limits the number of file |
5420 | one up as well: On \s-1OS/X,\s0 \f(CW\*(C`select\*(C'\fR actively limits the number of file |
5241 | descriptors you can pass in to 1024 \- your program suddenly crashes when |
5421 | descriptors you can pass in to 1024 \- your program suddenly crashes when |
5242 | you use more. |
5422 | you use more. |
5243 | .PP |
5423 | .PP |
5244 | There is an undocumented \*(L"workaround\*(R" for this \- defining |
5424 | There is an undocumented \*(L"workaround\*(R" for this \- defining |
5245 | \&\f(CW\*(C`_DARWIN_UNLIMITED_SELECT\*(C'\fR, which libev tries to use, so select \fIshould\fR |
5425 | \&\f(CW\*(C`_DARWIN_UNLIMITED_SELECT\*(C'\fR, which libev tries to use, so select \fIshould\fR |
5246 | work on \s-1OS/X\s0. |
5426 | work on \s-1OS/X.\s0 |
5247 | .SS "\s-1SOLARIS\s0 \s-1PROBLEMS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" |
5427 | .SS "\s-1SOLARIS PROBLEMS AND WORKAROUNDS\s0" |
5248 | .IX Subsection "SOLARIS PROBLEMS AND WORKAROUNDS" |
5428 | .IX Subsection "SOLARIS PROBLEMS AND WORKAROUNDS" |
5249 | \fI\f(CI\*(C`errno\*(C'\fI reentrancy\fR |
5429 | \fI\f(CI\*(C`errno\*(C'\fI reentrancy\fR |
5250 | .IX Subsection "errno reentrancy" |
5430 | .IX Subsection "errno reentrancy" |
5251 | .PP |
5431 | .PP |
5252 | The default compile environment on Solaris is unfortunately so |
5432 | The default compile environment on Solaris is unfortunately so |
… | |
… | |
5269 | great. |
5449 | great. |
5270 | .PP |
5450 | .PP |
5271 | If you can't get it to work, you can try running the program by setting |
5451 | If you can't get it to work, you can try running the program by setting |
5272 | the environment variable \f(CW\*(C`LIBEV_FLAGS=3\*(C'\fR to only allow \f(CW\*(C`poll\*(C'\fR and |
5452 | the environment variable \f(CW\*(C`LIBEV_FLAGS=3\*(C'\fR to only allow \f(CW\*(C`poll\*(C'\fR and |
5273 | \&\f(CW\*(C`select\*(C'\fR backends. |
5453 | \&\f(CW\*(C`select\*(C'\fR backends. |
5274 | .SS "\s-1AIX\s0 \s-1POLL\s0 \s-1BUG\s0" |
5454 | .SS "\s-1AIX POLL BUG\s0" |
5275 | .IX Subsection "AIX POLL BUG" |
5455 | .IX Subsection "AIX POLL BUG" |
5276 | \&\s-1AIX\s0 unfortunately has a broken \f(CW\*(C`poll.h\*(C'\fR header. Libev works around |
5456 | \&\s-1AIX\s0 unfortunately has a broken \f(CW\*(C`poll.h\*(C'\fR header. Libev works around |
5277 | this by trying to avoid the poll backend altogether (i.e. it's not even |
5457 | this by trying to avoid the poll backend altogether (i.e. it's not even |
5278 | compiled in), which normally isn't a big problem as \f(CW\*(C`select\*(C'\fR works fine |
5458 | compiled in), which normally isn't a big problem as \f(CW\*(C`select\*(C'\fR works fine |
5279 | with large bitsets on \s-1AIX\s0, and \s-1AIX\s0 is dead anyway. |
5459 | with large bitsets on \s-1AIX,\s0 and \s-1AIX\s0 is dead anyway. |
5280 | .SS "\s-1WIN32\s0 \s-1PLATFORM\s0 \s-1LIMITATIONS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" |
5460 | .SS "\s-1WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS\s0" |
5281 | .IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS" |
5461 | .IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS" |
5282 | \fIGeneral issues\fR |
5462 | \fIGeneral issues\fR |
5283 | .IX Subsection "General issues" |
5463 | .IX Subsection "General issues" |
5284 | .PP |
5464 | .PP |
5285 | Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev |
5465 | Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev |
… | |
… | |
5354 | \& #define EV_USE_SELECT 1 |
5534 | \& #define EV_USE_SELECT 1 |
5355 | \& #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
5535 | \& #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
5356 | .Ve |
5536 | .Ve |
5357 | .PP |
5537 | .PP |
5358 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
5538 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
5359 | complexity in the O(nA\*^X) range when using win32. |
5539 | complexity in the O(nX) range when using win32. |
5360 | .PP |
5540 | .PP |
5361 | \fILimited number of file descriptors\fR |
5541 | \fILimited number of file descriptors\fR |
5362 | .IX Subsection "Limited number of file descriptors" |
5542 | .IX Subsection "Limited number of file descriptors" |
5363 | .PP |
5543 | .PP |
5364 | Windows has numerous arbitrary (and low) limits on things. |
5544 | Windows has numerous arbitrary (and low) limits on things. |
… | |
… | |
5380 | by calling \f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR |
5560 | by calling \f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR |
5381 | (another arbitrary limit), but is broken in many versions of the Microsoft |
5561 | (another arbitrary limit), but is broken in many versions of the Microsoft |
5382 | runtime libraries. This might get you to about \f(CW512\fR or \f(CW2048\fR sockets |
5562 | runtime libraries. This might get you to about \f(CW512\fR or \f(CW2048\fR sockets |
5383 | (depending on windows version and/or the phase of the moon). To get more, |
5563 | (depending on windows version and/or the phase of the moon). To get more, |
5384 | you need to wrap all I/O functions and provide your own fd management, but |
5564 | you need to wrap all I/O functions and provide your own fd management, but |
5385 | the cost of calling select (O(nA\*^X)) will likely make this unworkable. |
5565 | the cost of calling select (O(nX)) will likely make this unworkable. |
5386 | .SS "\s-1PORTABILITY\s0 \s-1REQUIREMENTS\s0" |
5566 | .SS "\s-1PORTABILITY REQUIREMENTS\s0" |
5387 | .IX Subsection "PORTABILITY REQUIREMENTS" |
5567 | .IX Subsection "PORTABILITY REQUIREMENTS" |
5388 | In addition to a working ISO-C implementation and of course the |
5568 | In addition to a working ISO-C implementation and of course the |
5389 | backend-specific APIs, libev relies on a few additional extensions: |
5569 | backend-specific APIs, libev relies on a few additional extensions: |
5390 | .ie n .IP """void (*)(ev_watcher_type *, int revents)"" must have compatible calling conventions regardless of ""ev_watcher_type *""." 4 |
5570 | .ie n .IP """void (*)(ev_watcher_type *, int revents)"" must have compatible calling conventions regardless of ""ev_watcher_type *""." 4 |
5391 | .el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4 |
5571 | .el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4 |
5392 | .IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *." |
5572 | .IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *." |
5393 | Libev assumes not only that all watcher pointers have the same internal |
5573 | Libev assumes not only that all watcher pointers have the same internal |
5394 | structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO\s0 C for example), but it also |
5574 | structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO C\s0 for example), but it also |
5395 | assumes that the same (machine) code can be used to call any watcher |
5575 | assumes that the same (machine) code can be used to call any watcher |
5396 | callback: The watcher callbacks have different type signatures, but libev |
5576 | callback: The watcher callbacks have different type signatures, but libev |
5397 | calls them using an \f(CW\*(C`ev_watcher *\*(C'\fR internally. |
5577 | calls them using an \f(CW\*(C`ev_watcher *\*(C'\fR internally. |
|
|
5578 | .IP "null pointers and integer zero are represented by 0 bytes" 4 |
|
|
5579 | .IX Item "null pointers and integer zero are represented by 0 bytes" |
|
|
5580 | Libev uses \f(CW\*(C`memset\*(C'\fR to initialise structs and arrays to \f(CW0\fR bytes, and |
|
|
5581 | relies on this setting pointers and integers to null. |
5398 | .IP "pointer accesses must be thread-atomic" 4 |
5582 | .IP "pointer accesses must be thread-atomic" 4 |
5399 | .IX Item "pointer accesses must be thread-atomic" |
5583 | .IX Item "pointer accesses must be thread-atomic" |
5400 | Accessing a pointer value must be atomic, it must both be readable and |
5584 | Accessing a pointer value must be atomic, it must both be readable and |
5401 | writable in one piece \- this is the case on all current architectures. |
5585 | writable in one piece \- this is the case on all current architectures. |
5402 | .ie n .IP """sig_atomic_t volatile"" must be thread-atomic as well" 4 |
5586 | .ie n .IP """sig_atomic_t volatile"" must be thread-atomic as well" 4 |
… | |
… | |
5420 | except the initial one, and run the signal handling loop in the initial |
5604 | except the initial one, and run the signal handling loop in the initial |
5421 | thread as well. |
5605 | thread as well. |
5422 | .ie n .IP """long"" must be large enough for common memory allocation sizes" 4 |
5606 | .ie n .IP """long"" must be large enough for common memory allocation sizes" 4 |
5423 | .el .IP "\f(CWlong\fR must be large enough for common memory allocation sizes" 4 |
5607 | .el .IP "\f(CWlong\fR must be large enough for common memory allocation sizes" 4 |
5424 | .IX Item "long must be large enough for common memory allocation sizes" |
5608 | .IX Item "long must be large enough for common memory allocation sizes" |
5425 | To improve portability and simplify its \s-1API\s0, libev uses \f(CW\*(C`long\*(C'\fR internally |
5609 | To improve portability and simplify its \s-1API,\s0 libev uses \f(CW\*(C`long\*(C'\fR internally |
5426 | instead of \f(CW\*(C`size_t\*(C'\fR when allocating its data structures. On non-POSIX |
5610 | instead of \f(CW\*(C`size_t\*(C'\fR when allocating its data structures. On non-POSIX |
5427 | systems (Microsoft...) this might be unexpectedly low, but is still at |
5611 | systems (Microsoft...) this might be unexpectedly low, but is still at |
5428 | least 31 bits everywhere, which is enough for hundreds of millions of |
5612 | least 31 bits everywhere, which is enough for hundreds of millions of |
5429 | watchers. |
5613 | watchers. |
5430 | .ie n .IP """double"" must hold a time value in seconds with enough accuracy" 4 |
5614 | .ie n .IP """double"" must hold a time value in seconds with enough accuracy" 4 |
… | |
… | |
5432 | .IX Item "double must hold a time value in seconds with enough accuracy" |
5616 | .IX Item "double must hold a time value in seconds with enough accuracy" |
5433 | The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to |
5617 | The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to |
5434 | have at least 51 bits of mantissa (and 9 bits of exponent), which is |
5618 | have at least 51 bits of mantissa (and 9 bits of exponent), which is |
5435 | good enough for at least into the year 4000 with millisecond accuracy |
5619 | good enough for at least into the year 4000 with millisecond accuracy |
5436 | (the design goal for libev). This requirement is overfulfilled by |
5620 | (the design goal for libev). This requirement is overfulfilled by |
5437 | implementations using \s-1IEEE\s0 754, which is basically all existing ones. |
5621 | implementations using \s-1IEEE 754,\s0 which is basically all existing ones. |
5438 | .Sp |
5622 | .Sp |
5439 | With \s-1IEEE\s0 754 doubles, you get microsecond accuracy until at least the |
5623 | With \s-1IEEE 754\s0 doubles, you get microsecond accuracy until at least the |
5440 | year 2255 (and millisecond accuracy till the year 287396 \- by then, libev |
5624 | year 2255 (and millisecond accuracy till the year 287396 \- by then, libev |
5441 | is either obsolete or somebody patched it to use \f(CW\*(C`long double\*(C'\fR or |
5625 | is either obsolete or somebody patched it to use \f(CW\*(C`long double\*(C'\fR or |
5442 | something like that, just kidding). |
5626 | something like that, just kidding). |
5443 | .PP |
5627 | .PP |
5444 | If you know of other additional requirements drop me a note. |
5628 | If you know of other additional requirements drop me a note. |
… | |
… | |
5506 | calls in the current loop iteration and the loop is currently |
5690 | calls in the current loop iteration and the loop is currently |
5507 | blocked. Checking for async and signal events involves iterating over all |
5691 | blocked. Checking for async and signal events involves iterating over all |
5508 | running async watchers or all signal numbers. |
5692 | running async watchers or all signal numbers. |
5509 | .SH "PORTING FROM LIBEV 3.X TO 4.X" |
5693 | .SH "PORTING FROM LIBEV 3.X TO 4.X" |
5510 | .IX Header "PORTING FROM LIBEV 3.X TO 4.X" |
5694 | .IX Header "PORTING FROM LIBEV 3.X TO 4.X" |
5511 | The major version 4 introduced some incompatible changes to the \s-1API\s0. |
5695 | The major version 4 introduced some incompatible changes to the \s-1API.\s0 |
5512 | .PP |
5696 | .PP |
5513 | At the moment, the \f(CW\*(C`ev.h\*(C'\fR header file provides compatibility definitions |
5697 | At the moment, the \f(CW\*(C`ev.h\*(C'\fR header file provides compatibility definitions |
5514 | for all changes, so most programs should still compile. The compatibility |
5698 | for all changes, so most programs should still compile. The compatibility |
5515 | layer might be removed in later versions of libev, so better update to the |
5699 | layer might be removed in later versions of libev, so better update to the |
5516 | new \s-1API\s0 early than late. |
5700 | new \s-1API\s0 early than late. |
5517 | .ie n .IP """EV_COMPAT3"" backwards compatibility mechanism" 4 |
5701 | .ie n .IP """EV_COMPAT3"" backwards compatibility mechanism" 4 |
5518 | .el .IP "\f(CWEV_COMPAT3\fR backwards compatibility mechanism" 4 |
5702 | .el .IP "\f(CWEV_COMPAT3\fR backwards compatibility mechanism" 4 |
5519 | .IX Item "EV_COMPAT3 backwards compatibility mechanism" |
5703 | .IX Item "EV_COMPAT3 backwards compatibility mechanism" |
5520 | The backward compatibility mechanism can be controlled by |
5704 | The backward compatibility mechanism can be controlled by |
5521 | \&\f(CW\*(C`EV_COMPAT3\*(C'\fR. See \*(L"\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0\*(R" in the \*(L"\s-1EMBEDDING\s0\*(R" |
5705 | \&\f(CW\*(C`EV_COMPAT3\*(C'\fR. See \*(L"\s-1PREPROCESSOR SYMBOLS/MACROS\*(R"\s0 in the \*(L"\s-1EMBEDDING\*(R"\s0 |
5522 | section. |
5706 | section. |
5523 | .ie n .IP """ev_default_destroy"" and ""ev_default_fork"" have been removed" 4 |
5707 | .ie n .IP """ev_default_destroy"" and ""ev_default_fork"" have been removed" 4 |
5524 | .el .IP "\f(CWev_default_destroy\fR and \f(CWev_default_fork\fR have been removed" 4 |
5708 | .el .IP "\f(CWev_default_destroy\fR and \f(CWev_default_fork\fR have been removed" 4 |
5525 | .IX Item "ev_default_destroy and ev_default_fork have been removed" |
5709 | .IX Item "ev_default_destroy and ev_default_fork have been removed" |
5526 | These calls can be replaced easily by their \f(CW\*(C`ev_loop_xxx\*(C'\fR counterparts: |
5710 | These calls can be replaced easily by their \f(CW\*(C`ev_loop_xxx\*(C'\fR counterparts: |
… | |
… | |
5566 | .SH "GLOSSARY" |
5750 | .SH "GLOSSARY" |
5567 | .IX Header "GLOSSARY" |
5751 | .IX Header "GLOSSARY" |
5568 | .IP "active" 4 |
5752 | .IP "active" 4 |
5569 | .IX Item "active" |
5753 | .IX Item "active" |
5570 | A watcher is active as long as it has been started and not yet stopped. |
5754 | A watcher is active as long as it has been started and not yet stopped. |
5571 | See \*(L"\s-1WATCHER\s0 \s-1STATES\s0\*(R" for details. |
5755 | See \*(L"\s-1WATCHER STATES\*(R"\s0 for details. |
5572 | .IP "application" 4 |
5756 | .IP "application" 4 |
5573 | .IX Item "application" |
5757 | .IX Item "application" |
5574 | In this document, an application is whatever is using libev. |
5758 | In this document, an application is whatever is using libev. |
5575 | .IP "backend" 4 |
5759 | .IP "backend" 4 |
5576 | .IX Item "backend" |
5760 | .IX Item "backend" |
… | |
… | |
5603 | The model used to describe how an event loop handles and processes |
5787 | The model used to describe how an event loop handles and processes |
5604 | watchers and events. |
5788 | watchers and events. |
5605 | .IP "pending" 4 |
5789 | .IP "pending" 4 |
5606 | .IX Item "pending" |
5790 | .IX Item "pending" |
5607 | A watcher is pending as soon as the corresponding event has been |
5791 | A watcher is pending as soon as the corresponding event has been |
5608 | detected. See \*(L"\s-1WATCHER\s0 \s-1STATES\s0\*(R" for details. |
5792 | detected. See \*(L"\s-1WATCHER STATES\*(R"\s0 for details. |
5609 | .IP "real time" 4 |
5793 | .IP "real time" 4 |
5610 | .IX Item "real time" |
5794 | .IX Item "real time" |
5611 | The physical time that is observed. It is apparently strictly monotonic :) |
5795 | The physical time that is observed. It is apparently strictly monotonic :) |
5612 | .IP "wall-clock time" 4 |
5796 | .IP "wall-clock time" 4 |
5613 | .IX Item "wall-clock time" |
5797 | .IX Item "wall-clock time" |