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135 | .IX Title "LIBEV 3" |
135 | .IX Title "LIBEV 3" |
136 | .TH LIBEV 3 "2014-09-05" "libev-4.15" "libev - high performance full featured event loop" |
136 | .TH LIBEV 3 "2020-01-22" "libev-4.31" "libev - high performance full featured event loop" |
137 | .\" For nroff, turn off justification. Always turn off hyphenation; it makes |
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138 | .\" way too many mistakes in technical documents. |
138 | .\" way too many mistakes in technical documents. |
139 | .if n .ad l |
139 | .if n .ad l |
140 | .nh |
140 | .nh |
141 | .SH "NAME" |
141 | .SH "NAME" |
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240 | 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 |
241 | 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 |
242 | watcher. |
242 | watcher. |
243 | .SS "\s-1FEATURES\s0" |
243 | .SS "\s-1FEATURES\s0" |
244 | .IX Subsection "FEATURES" |
244 | .IX Subsection "FEATURES" |
245 | 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 |
246 | 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 |
247 | 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 |
248 | (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 |
249 | 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 |
250 | 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 |
251 | (\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 |
252 | 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 |
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 |
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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291 | 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 |
292 | 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, |
293 | 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 |
294 | the libev caller and need to be fixed there. |
294 | the libev caller and need to be fixed there. |
295 | .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 |
296 | 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 |
297 | extensive consistency checking code. These do not trigger under normal |
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298 | 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. |
299 | .SH "GLOBAL FUNCTIONS" |
303 | .SH "GLOBAL FUNCTIONS" |
300 | .IX Header "GLOBAL FUNCTIONS" |
304 | .IX Header "GLOBAL FUNCTIONS" |
301 | These functions can be called anytime, even before initialising the |
305 | These functions can be called anytime, even before initialising the |
302 | library in any way. |
306 | library in any way. |
303 | .IP "ev_tstamp ev_time ()" 4 |
307 | .IP "ev_tstamp ev_time ()" 4 |
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392 | .Sp |
396 | .Sp |
393 | You could override this function in high-availability programs to, say, |
397 | You could override this function in high-availability programs to, say, |
394 | 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, |
395 | 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. |
396 | .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 |
397 | 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 |
398 | retries (example requires a standards-compliant \f(CW\*(C`realloc\*(C'\fR). |
418 | retries. |
399 | .Sp |
419 | .Sp |
400 | .Vb 6 |
420 | .Vb 8 |
401 | \& static void * |
421 | \& static void * |
402 | \& persistent_realloc (void *ptr, size_t size) |
422 | \& persistent_realloc (void *ptr, size_t size) |
403 | \& { |
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 | \& |
404 | \& for (;;) |
430 | \& for (;;) |
405 | \& { |
431 | \& { |
406 | \& void *newptr = realloc (ptr, size); |
432 | \& void *newptr = realloc (ptr, size); |
407 | \& |
433 | \& |
408 | \& if (newptr) |
434 | \& if (newptr) |
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536 | 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. |
537 | .Sp |
563 | .Sp |
538 | 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, |
539 | 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 |
540 | 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 |
541 | 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 |
542 | 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 |
543 | \&\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). |
544 | .Sp |
571 | .Sp |
545 | 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 |
546 | forget about forgetting to tell libev about forking) when you use this |
573 | forget about forgetting to tell libev about forking, although you still |
547 | flag. |
574 | have to ignore \f(CW\*(C`SIGPIPE\*(C'\fR) when you use this flag. |
548 | .Sp |
575 | .Sp |
549 | 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 |
550 | environment variable. |
577 | environment variable. |
551 | .ie n .IP """EVFLAG_NOINOTIFY""" 4 |
578 | .ie n .IP """EVFLAG_NOINOTIFY""" 4 |
552 | .el .IP "\f(CWEVFLAG_NOINOTIFY\fR" 4 |
579 | .el .IP "\f(CWEVFLAG_NOINOTIFY\fR" 4 |
… | |
… | |
579 | 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 |
580 | unblocking the signals. |
607 | unblocking the signals. |
581 | .Sp |
608 | .Sp |
582 | 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 |
583 | \&\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. |
584 | .Sp |
618 | .Sp |
585 | 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. |
586 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
622 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
587 | .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 |
588 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
624 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
589 | 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 |
590 | 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, |
591 | 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 |
592 | 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 |
593 | 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. |
594 | .Sp |
630 | .Sp |
… | |
… | |
603 | \&\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 |
604 | \&\f(CW\*(C`exceptfds\*(C'\fR set on that platform). |
640 | \&\f(CW\*(C`exceptfds\*(C'\fR set on that platform). |
605 | .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 |
606 | .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 |
607 | .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)" |
608 | 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 |
609 | than select, but handles sparse fds better and has no artificial |
645 | than select, but handles sparse fds better and has no artificial |
610 | 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 |
611 | 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, |
612 | 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 |
613 | performance tips. |
649 | performance tips. |
… | |
… | |
615 | 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 |
616 | \&\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. |
617 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
653 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
618 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
654 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
619 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
655 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
620 | 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 |
621 | kernels). |
657 | kernels). |
622 | .Sp |
658 | .Sp |
623 | 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 |
624 | it scales phenomenally better. While poll and select usually scale like |
660 | it scales phenomenally better. While poll and select usually scale like |
625 | 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 |
… | |
… | |
671 | 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 |
672 | 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 |
673 | the usage. So sad. |
709 | the usage. So sad. |
674 | .Sp |
710 | .Sp |
675 | 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 |
676 | all kernel versions tested so far. |
712 | a lot of kernel revisions, but probably(!) works in current versions. |
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713 | .Sp |
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714 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
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715 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
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716 | .ie n .IP """EVBACKEND_LINUXAIO"" (value 64, Linux)" 4 |
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717 | .el .IP "\f(CWEVBACKEND_LINUXAIO\fR (value 64, Linux)" 4 |
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718 | .IX Item "EVBACKEND_LINUXAIO (value 64, Linux)" |
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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 |
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720 | only tries to use it in 4.19+). |
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721 | .Sp |
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722 | This is another Linux train wreck of an event interface. |
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723 | .Sp |
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724 | If this backend works for you (as of this writing, it was very |
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725 | experimental), it is the best event interface available on Linux and might |
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726 | be well worth enabling it \- if it isn't available in your kernel this will |
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727 | be detected and this backend will be skipped. |
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728 | .Sp |
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729 | This backend can batch oneshot requests and supports a user-space ring |
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730 | buffer to receive events. It also doesn't suffer from most of the design |
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731 | problems of epoll (such as not being able to remove event sources from |
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732 | the epoll set), and generally sounds too good to be true. Because, this |
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733 | being the Linux kernel, of course it suffers from a whole new set of |
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734 | limitations, forcing you to fall back to epoll, inheriting all its design |
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735 | issues. |
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736 | .Sp |
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737 | For one, it is not easily embeddable (but probably could be done using |
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738 | an event fd at some extra overhead). It also is subject to a system wide |
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739 | limit that can be configured in \fI/proc/sys/fs/aio\-max\-nr\fR. If no \s-1AIO\s0 |
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740 | requests are left, this backend will be skipped during initialisation, and |
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741 | will switch to epoll when the loop is active. |
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742 | .Sp |
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743 | Most problematic in practice, however, is that not all file descriptors |
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744 | work with it. For example, in Linux 5.1, \s-1TCP\s0 sockets, pipes, event fds, |
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745 | files, \fI/dev/null\fR and many others are supported, but ttys do not work |
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746 | properly (a known bug that the kernel developers don't care about, see |
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747 | <https://lore.kernel.org/patchwork/patch/1047453/>), so this is not |
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748 | (yet?) a generic event polling interface. |
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749 | .Sp |
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750 | Overall, it seems the Linux developers just don't want it to have a |
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751 | generic event handling mechanism other than \f(CW\*(C`select\*(C'\fR or \f(CW\*(C`poll\*(C'\fR. |
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752 | .Sp |
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753 | To work around all these problem, the current version of libev uses its |
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754 | epoll backend as a fallback for file descriptor types that do not work. Or |
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755 | falls back completely to epoll if the kernel acts up. |
677 | .Sp |
756 | .Sp |
678 | 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 |
679 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
758 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
680 | .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 |
681 | .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 |
682 | .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" |
761 | .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" |
683 | Kqueue deserves special mention, as at the time of this writing, it |
762 | Kqueue deserves special mention, as at the time this backend was |
684 | 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 |
685 | with anything but sockets and pipes, except on Darwin, where of course |
764 | work reliably with anything but sockets and pipes, except on Darwin, |
686 | it's completely useless). Unlike epoll, however, whose brokenness |
765 | where of course it's completely useless). Unlike epoll, however, whose |
687 | 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) |
688 | 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 |
689 | \&\*(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 |
690 | \&\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 |
691 | system like NetBSD. |
770 | known-to-be-good (\-enough) system like NetBSD. |
692 | .Sp |
771 | .Sp |
693 | 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 |
694 | 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 |
695 | 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. |
696 | .Sp |
775 | .Sp |
697 | 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 |
698 | 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 |
699 | 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 |
700 | 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 |
701 | 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 |
702 | 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 |
703 | drops fds silently in similarly hard-to-detect cases. |
782 | drops fds silently in similarly hard-to-detect cases. |
704 | .Sp |
783 | .Sp |
705 | This backend usually performs well under most conditions. |
784 | This backend usually performs well under most conditions. |
706 | .Sp |
785 | .Sp |
707 | While nominally embeddable in other event loops, this doesn't work |
786 | While nominally embeddable in other event loops, this doesn't work |
… | |
… | |
785 | used if available. |
864 | used if available. |
786 | .Sp |
865 | .Sp |
787 | .Vb 1 |
866 | .Vb 1 |
788 | \& 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); |
789 | .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 |
790 | .RE |
877 | .RE |
791 | .IP "ev_loop_destroy (loop)" 4 |
878 | .IP "ev_loop_destroy (loop)" 4 |
792 | .IX Item "ev_loop_destroy (loop)" |
879 | .IX Item "ev_loop_destroy (loop)" |
793 | Destroys an event loop object (frees all memory and kernel state |
880 | Destroys an event loop object (frees all memory and kernel state |
794 | 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 |
… | |
… | |
816 | to reinitialise the kernel state for backends that have one. Despite |
903 | to reinitialise the kernel state for backends that have one. Despite |
817 | the name, you can call it anytime you are allowed to start or stop |
904 | the name, you can call it anytime you are allowed to start or stop |
818 | watchers (except inside an \f(CW\*(C`ev_prepare\*(C'\fR callback), but it makes most |
905 | watchers (except inside an \f(CW\*(C`ev_prepare\*(C'\fR callback), but it makes most |
819 | sense after forking, in the child process. You \fImust\fR call it (or use |
906 | sense after forking, in the child process. You \fImust\fR call it (or use |
820 | \&\f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR) in the child before resuming or calling \f(CW\*(C`ev_run\*(C'\fR. |
907 | \&\f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR) in the child before resuming or calling \f(CW\*(C`ev_run\*(C'\fR. |
|
|
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. |
821 | .Sp |
911 | .Sp |
822 | 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 |
823 | 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 |
824 | because some kernel interfaces *cough* \fIkqueue\fR *cough* do funny things |
914 | because some kernel interfaces *cough* \fIkqueue\fR *cough* do funny things |
825 | during fork. |
915 | during fork. |
… | |
… | |
1361 | bug in your program. |
1451 | bug in your program. |
1362 | .Sp |
1452 | .Sp |
1363 | 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 |
1364 | 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 |
1365 | 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 |
1366 | 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 |
1367 | 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 |
1368 | thing, so beware. |
1458 | thing, so beware. |
1369 | .SS "\s-1GENERIC WATCHER FUNCTIONS\s0" |
1459 | .SS "\s-1GENERIC WATCHER FUNCTIONS\s0" |
1370 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
1460 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
1371 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
1461 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
… | |
… | |
1573 | .IX Subsection "WATCHER PRIORITY MODELS" |
1663 | .IX Subsection "WATCHER PRIORITY MODELS" |
1574 | Many event loops support \fIwatcher priorities\fR, which are usually small |
1664 | Many event loops support \fIwatcher priorities\fR, which are usually small |
1575 | integers that influence the ordering of event callback invocation |
1665 | integers that influence the ordering of event callback invocation |
1576 | between watchers in some way, all else being equal. |
1666 | between watchers in some way, all else being equal. |
1577 | .PP |
1667 | .PP |
1578 | 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 |
1579 | description for the more technical details such as the actual priority |
1669 | description for the more technical details such as the actual priority |
1580 | range. |
1670 | range. |
1581 | .PP |
1671 | .PP |
1582 | 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 |
1583 | by event loops: |
1673 | by event loops: |
… | |
… | |
1677 | .IX Header "WATCHER TYPES" |
1767 | .IX Header "WATCHER TYPES" |
1678 | This section describes each watcher in detail, but will not repeat |
1768 | This section describes each watcher in detail, but will not repeat |
1679 | information given in the last section. Any initialisation/set macros, |
1769 | information given in the last section. Any initialisation/set macros, |
1680 | functions and members specific to the watcher type are explained. |
1770 | functions and members specific to the watcher type are explained. |
1681 | .PP |
1771 | .PP |
1682 | 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 |
1683 | 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 |
1684 | 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 |
1685 | 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 |
1686 | 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 |
1687 | 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 |
1688 | 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 |
1689 | 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. |
1690 | .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?" |
1691 | .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?" |
1692 | .IX Subsection "ev_io - is this file descriptor readable or writable?" |
1785 | .IX Subsection "ev_io - is this file descriptor readable or writable?" |
1693 | 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 |
1694 | 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 |
… | |
… | |
1722 | But really, best use non-blocking mode. |
1815 | But really, best use non-blocking mode. |
1723 | .PP |
1816 | .PP |
1724 | \fIThe special problem of disappearing file descriptors\fR |
1817 | \fIThe special problem of disappearing file descriptors\fR |
1725 | .IX Subsection "The special problem of disappearing file descriptors" |
1818 | .IX Subsection "The special problem of disappearing file descriptors" |
1726 | .PP |
1819 | .PP |
1727 | 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 |
1728 | 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 |
1729 | 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 |
1730 | 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 |
1731 | 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 |
1732 | 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, |
1733 | fact, a different file descriptor. |
1826 | in fact, a different file descriptor. |
1734 | .PP |
1827 | .PP |
1735 | 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 |
1736 | 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 |
1737 | will assume that this is potentially a new file descriptor, otherwise |
1830 | will assume that this is potentially a new file descriptor, otherwise |
1738 | 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 |
… | |
… | |
1790 | reuse the same code path. |
1883 | reuse the same code path. |
1791 | .PP |
1884 | .PP |
1792 | \fIThe special problem of fork\fR |
1885 | \fIThe special problem of fork\fR |
1793 | .IX Subsection "The special problem of fork" |
1886 | .IX Subsection "The special problem of fork" |
1794 | .PP |
1887 | .PP |
1795 | 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 |
1796 | 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 |
1797 | 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. |
1798 | .PP |
1892 | .PP |
1799 | 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 |
1800 | ()\*(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 |
1801 | \&\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. |
1802 | .PP |
1896 | .PP |
… | |
… | |
1807 | 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 |
1808 | 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 |
1809 | this is sensible behaviour, for daemons, this is usually undesirable. |
1903 | this is sensible behaviour, for daemons, this is usually undesirable. |
1810 | .PP |
1904 | .PP |
1811 | So when you encounter spurious, unexplained daemon exits, make sure you |
1905 | So when you encounter spurious, unexplained daemon exits, make sure you |
1812 | 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 |
1813 | somewhere, as that would have given you a big clue). |
1907 | somewhere, as that would have given you a big clue). |
1814 | .PP |
1908 | .PP |
1815 | \fIThe special problem of \fIaccept()\fIing when you can't\fR |
1909 | \fIThe special problem of \f(BIaccept()\fIing when you can't\fR |
1816 | .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" |
1817 | .PP |
1911 | .PP |
1818 | 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, |
1819 | 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 |
1820 | connection from the pending queue in all error cases. |
1914 | connection from the pending queue in all error cases. |
1821 | .PP |
1915 | .PP |
1822 | For example, larger servers often run out of file descriptors (because |
1916 | For example, larger servers often run out of file descriptors (because |
1823 | of resource limits), causing \f(CW\*(C`accept\*(C'\fR to fail with \f(CW\*(C`ENFILE\*(C'\fR but not |
1917 | of resource limits), causing \f(CW\*(C`accept\*(C'\fR to fail with \f(CW\*(C`ENFILE\*(C'\fR but not |
… | |
… | |
1861 | .IX Item "ev_io_set (ev_io *, int fd, int events)" |
1955 | .IX Item "ev_io_set (ev_io *, int fd, int events)" |
1862 | .PD |
1956 | .PD |
1863 | 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 |
1864 | 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 |
1865 | \&\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. |
1866 | .IP "int fd [read\-only]" 4 |
1966 | .IP "int fd [no\-modify]" 4 |
1867 | .IX Item "int fd [read-only]" |
1967 | .IX Item "int fd [no-modify]" |
1868 | 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. |
1869 | .IP "int events [read\-only]" 4 |
1971 | .IP "int events [no\-modify]" 4 |
1870 | .IX Item "int events [read-only]" |
1972 | .IX Item "int events [no-modify]" |
1871 | 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. |
1872 | .PP |
1979 | .PP |
1873 | \fIExamples\fR |
1980 | \fIExamples\fR |
1874 | .IX Subsection "Examples" |
1981 | .IX Subsection "Examples" |
1875 | .PP |
1982 | .PP |
1876 | 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 |
… | |
… | |
2247 | .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)" |
2248 | .PD 0 |
2355 | .PD 0 |
2249 | .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 |
2250 | .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)" |
2251 | .PD |
2358 | .PD |
2252 | 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 |
2253 | 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 |
2254 | reached. If it is positive, then the timer will automatically be |
2361 | automatically be stopped once the timeout is reached. If it is positive, |
2255 | 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 |
2256 | until stopped manually. |
2363 | seconds later, again, and again, until stopped manually. |
2257 | .Sp |
2364 | .Sp |
2258 | 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 |
2259 | 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 |
2260 | trigger at exactly 10 second intervals. If, however, your program cannot |
2367 | trigger at exactly 10 second intervals. If, however, your program cannot |
2261 | 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 |
… | |
… | |
2343 | 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 |
2344 | (and unfortunately a bit complex). |
2451 | (and unfortunately a bit complex). |
2345 | .PP |
2452 | .PP |
2346 | 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 |
2347 | 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 |
2348 | (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 |
2349 | 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 |
2350 | 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 |
2351 | wrist-watch). |
2458 | wrist-watch). |
2352 | .PP |
2459 | .PP |
2353 | 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 |
… | |
… | |
2358 | \&\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 |
2359 | it, as it uses a relative timeout). |
2466 | it, as it uses a relative timeout). |
2360 | .PP |
2467 | .PP |
2361 | \&\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 |
2362 | 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 |
2363 | 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 |
2364 | those cannot react to time jumps. |
2471 | watchers, as those cannot react to time jumps. |
2365 | .PP |
2472 | .PP |
2366 | 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 |
2367 | 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 |
2368 | 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 |
2369 | 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 |
… | |
… | |
2430 | 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 |
2431 | ignored. Instead, each time the periodic watcher gets scheduled, the |
2538 | ignored. Instead, each time the periodic watcher gets scheduled, the |
2432 | 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 |
2433 | current time as second argument. |
2540 | current time as second argument. |
2434 | .Sp |
2541 | .Sp |
2435 | \&\s-1NOTE: \s0\fIThis callback \s-1MUST NOT\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, |
2436 | 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 |
2437 | allowed by documentation here\fR. |
2544 | allowed by documentation here\fR. |
2438 | .Sp |
2545 | .Sp |
2439 | 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 |
2440 | 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 |
… | |
… | |
2454 | It must return the next time to trigger, based on the passed time value |
2561 | It must return the next time to trigger, based on the passed time value |
2455 | (that is, the lowest time value larger than to the second argument). It |
2562 | (that is, the lowest time value larger than to the second argument). It |
2456 | will usually be called just before the callback will be triggered, but |
2563 | will usually be called just before the callback will be triggered, but |
2457 | might be called at other times, too. |
2564 | might be called at other times, too. |
2458 | .Sp |
2565 | .Sp |
2459 | \&\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 |
2460 | 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. |
2461 | .Sp |
2568 | .Sp |
2462 | 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 |
2463 | 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 |
2464 | 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 |
2465 | 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 |
2466 | 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). |
2467 | .RE |
2594 | .RE |
2468 | .RS 4 |
2595 | .RS 4 |
2469 | .RE |
2596 | .RE |
2470 | .IP "ev_periodic_again (loop, ev_periodic *)" 4 |
2597 | .IP "ev_periodic_again (loop, ev_periodic *)" 4 |
2471 | .IX Item "ev_periodic_again (loop, ev_periodic *)" |
2598 | .IX Item "ev_periodic_again (loop, ev_periodic *)" |
… | |
… | |
2589 | The simplest way to ensure that the signal mask is reset in the child is |
2716 | The simplest way to ensure that the signal mask is reset in the child is |
2590 | to install a fork handler with \f(CW\*(C`pthread_atfork\*(C'\fR that resets it. That will |
2717 | to install a fork handler with \f(CW\*(C`pthread_atfork\*(C'\fR that resets it. That will |
2591 | catch fork calls done by libraries (such as the libc) as well. |
2718 | catch fork calls done by libraries (such as the libc) as well. |
2592 | .PP |
2719 | .PP |
2593 | In current versions of libev, the signal will not be blocked indefinitely |
2720 | In current versions of libev, the signal will not be blocked indefinitely |
2594 | unless you use the \f(CW\*(C`signalfd\*(C'\fR \s-1API \s0(\f(CW\*(C`EV_SIGNALFD\*(C'\fR). While this reduces |
2721 | unless you use the \f(CW\*(C`signalfd\*(C'\fR \s-1API\s0 (\f(CW\*(C`EV_SIGNALFD\*(C'\fR). While this reduces |
2595 | the window of opportunity for problems, it will not go away, as libev |
2722 | the window of opportunity for problems, it will not go away, as libev |
2596 | \&\fIhas\fR to modify the signal mask, at least temporarily. |
2723 | \&\fIhas\fR to modify the signal mask, at least temporarily. |
2597 | .PP |
2724 | .PP |
2598 | So I can't stress this enough: \fIIf you do not reset your signal mask when |
2725 | So I can't stress this enough: \fIIf you do not reset your signal mask when |
2599 | you expect it to be empty, you have a race condition in your code\fR. This |
2726 | you expect it to be empty, you have a race condition in your code\fR. This |
… | |
… | |
3641 | 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 |
3642 | notification, and the callback being invoked. |
3769 | notification, and the callback being invoked. |
3643 | .SH "OTHER FUNCTIONS" |
3770 | .SH "OTHER FUNCTIONS" |
3644 | .IX Header "OTHER FUNCTIONS" |
3771 | .IX Header "OTHER FUNCTIONS" |
3645 | There are some other functions of possible interest. Described. Here. Now. |
3772 | There are some other functions of possible interest. Described. Here. Now. |
3646 | .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 |
3647 | .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)" |
3648 | 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 |
3649 | callback on whichever event happens first and automatically stops both |
3776 | callback on whichever event happens first and automatically stops both |
3650 | 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 |
3651 | 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 |
3652 | more watchers yourself. |
3779 | more watchers yourself. |
… | |
… | |
4052 | 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: |
4053 | .PP |
4180 | .PP |
4054 | .Vb 4 |
4181 | .Vb 4 |
4055 | \& // my_ev.h |
4182 | \& // my_ev.h |
4056 | \& #define EV_CB_DECLARE(type) struct my_coro *cb; |
4183 | \& #define EV_CB_DECLARE(type) struct my_coro *cb; |
4057 | \& #define EV_CB_INVOKE(watcher) switch_to ((watcher)\->cb); |
4184 | \& #define EV_CB_INVOKE(watcher) switch_to ((watcher)\->cb) |
4058 | \& #include "../libev/ev.h" |
4185 | \& #include "../libev/ev.h" |
4059 | \& |
4186 | \& |
4060 | \& // my_ev.c |
4187 | \& // my_ev.c |
4061 | \& #define EV_H "my_ev.h" |
4188 | \& #define EV_H "my_ev.h" |
4062 | \& #include "../libev/ev.c" |
4189 | \& #include "../libev/ev.c" |
… | |
… | |
4102 | 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 |
4103 | 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 |
4104 | will work fine. |
4231 | will work fine. |
4105 | .PP |
4232 | .PP |
4106 | Proper exception specifications might have to be added to callbacks passed |
4233 | Proper exception specifications might have to be added to callbacks passed |
4107 | to libev: exceptions may be thrown only from watcher callbacks, all |
4234 | to libev: exceptions may be thrown only from watcher callbacks, all other |
4108 | other callbacks (allocator, syserr, loop acquire/release and periodic |
4235 | callbacks (allocator, syserr, loop acquire/release and periodic reschedule |
4109 | 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 |
4110 | ()\*(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 |
4111 | 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: |
4112 | .PP |
4239 | .PP |
4113 | .Vb 6 |
4240 | .Vb 6 |
4114 | \& static void |
4241 | \& static void |
4115 | \& fatal_error (const char *msg) EV_THROW |
4242 | \& fatal_error (const char *msg) EV_NOEXCEPT |
4116 | \& { |
4243 | \& { |
4117 | \& perror (msg); |
4244 | \& perror (msg); |
4118 | \& abort (); |
4245 | \& abort (); |
4119 | \& } |
4246 | \& } |
4120 | \& |
4247 | \& |
… | |
… | |
4494 | \& #include "ev.c" |
4621 | \& #include "ev.c" |
4495 | .Ve |
4622 | .Ve |
4496 | .PP |
4623 | .PP |
4497 | This will automatically include \fIev.h\fR, too, and should be done in a |
4624 | This will automatically include \fIev.h\fR, too, and should be done in a |
4498 | single C source file only to provide the function implementations. To use |
4625 | single C source file only to provide the function implementations. To use |
4499 | it, do the same for \fIev.h\fR in all files wishing to use this \s-1API \s0(best |
4626 | it, do the same for \fIev.h\fR in all files wishing to use this \s-1API\s0 (best |
4500 | done by writing a wrapper around \fIev.h\fR that you can include instead and |
4627 | done by writing a wrapper around \fIev.h\fR that you can include instead and |
4501 | where you can put other configuration options): |
4628 | where you can put other configuration options): |
4502 | .PP |
4629 | .PP |
4503 | .Vb 2 |
4630 | .Vb 2 |
4504 | \& #define EV_STANDALONE 1 |
4631 | \& #define EV_STANDALONE 1 |
… | |
… | |
4518 | \& ev_vars.h |
4645 | \& ev_vars.h |
4519 | \& ev_wrap.h |
4646 | \& ev_wrap.h |
4520 | \& |
4647 | \& |
4521 | \& ev_win32.c required on win32 platforms only |
4648 | \& ev_win32.c required on win32 platforms only |
4522 | \& |
4649 | \& |
4523 | \& ev_select.c only when select backend is enabled (which is enabled by default) |
4650 | \& ev_select.c only when select backend is enabled |
4524 | \& ev_poll.c only when poll backend is enabled (disabled by default) |
4651 | \& ev_poll.c only when poll backend is enabled |
4525 | \& 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 |
4526 | \& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
4655 | \& ev_kqueue.c only when the kqueue backend is enabled |
4527 | \& 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 |
4528 | .Ve |
4657 | .Ve |
4529 | .PP |
4658 | .PP |
4530 | \&\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 |
4531 | to compile this single file. |
4660 | to compile this single file. |
4532 | .PP |
4661 | .PP |
… | |
… | |
4577 | 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 |
4578 | to redefine them before including \fIev.h\fR without breaking compatibility |
4707 | to redefine them before including \fIev.h\fR without breaking compatibility |
4579 | 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 |
4580 | 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 |
4581 | settings. |
4710 | settings. |
4582 | .IP "\s-1EV_COMPAT3 \s0(h)" 4 |
4711 | .IP "\s-1EV_COMPAT3\s0 (h)" 4 |
4583 | .IX Item "EV_COMPAT3 (h)" |
4712 | .IX Item "EV_COMPAT3 (h)" |
4584 | 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 |
4585 | release of libev comes with wrappers for the functions and symbols that |
4714 | release of libev comes with wrappers for the functions and symbols that |
4586 | have been renamed between libev version 3 and 4. |
4715 | have been renamed between libev version 3 and 4. |
4587 | .Sp |
4716 | .Sp |
… | |
… | |
4592 | typedef in that case. |
4721 | typedef in that case. |
4593 | .Sp |
4722 | .Sp |
4594 | In some future version, the default for \f(CW\*(C`EV_COMPAT3\*(C'\fR will become \f(CW0\fR, |
4723 | In some future version, the default for \f(CW\*(C`EV_COMPAT3\*(C'\fR will become \f(CW0\fR, |
4595 | and in some even more future version the compatibility code will be |
4724 | and in some even more future version the compatibility code will be |
4596 | removed completely. |
4725 | removed completely. |
4597 | .IP "\s-1EV_STANDALONE \s0(h)" 4 |
4726 | .IP "\s-1EV_STANDALONE\s0 (h)" 4 |
4598 | .IX Item "EV_STANDALONE (h)" |
4727 | .IX Item "EV_STANDALONE (h)" |
4599 | Must always be \f(CW1\fR if you do not use autoconf configuration, which |
4728 | Must always be \f(CW1\fR if you do not use autoconf configuration, which |
4600 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
4729 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
4601 | implementations for some libevent functions (such as logging, which is not |
4730 | implementations for some libevent functions (such as logging, which is not |
4602 | supported). It will also not define any of the structs usually found in |
4731 | supported). It will also not define any of the structs usually found in |
… | |
… | |
4643 | 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). |
4644 | .IP "\s-1EV_USE_NANOSLEEP\s0" 4 |
4773 | .IP "\s-1EV_USE_NANOSLEEP\s0" 4 |
4645 | .IX Item "EV_USE_NANOSLEEP" |
4774 | .IX Item "EV_USE_NANOSLEEP" |
4646 | 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 |
4647 | 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. |
4648 | .IP "\s-1EV_USE_EVENTFD\s0" 4 |
4798 | .IP "\s-1EV_USE_EVENTFD\s0" 4 |
4649 | .IX Item "EV_USE_EVENTFD" |
4799 | .IX Item "EV_USE_EVENTFD" |
4650 | 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 |
4651 | 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 |
4652 | \&\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. |
… | |
… | |
4711 | 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 |
4712 | \&\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, |
4713 | 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 |
4714 | 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 |
4715 | 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. |
4716 | .IP "\s-1EV_USE_KQUEUE\s0" 4 |
4877 | .IP "\s-1EV_USE_KQUEUE\s0" 4 |
4717 | .IX Item "EV_USE_KQUEUE" |
4878 | .IX Item "EV_USE_KQUEUE" |
4718 | 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 |
4719 | \&\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, |
4720 | 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 |
… | |
… | |
4760 | handler \*(L"locking\*(R" as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR |
4921 | handler \*(L"locking\*(R" as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR |
4761 | watchers. |
4922 | watchers. |
4762 | .Sp |
4923 | .Sp |
4763 | In the absence of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR |
4924 | In the absence of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR |
4764 | (from \fIsignal.h\fR), which is usually good enough on most platforms. |
4925 | (from \fIsignal.h\fR), which is usually good enough on most platforms. |
4765 | .IP "\s-1EV_H \s0(h)" 4 |
4926 | .IP "\s-1EV_H\s0 (h)" 4 |
4766 | .IX Item "EV_H (h)" |
4927 | .IX Item "EV_H (h)" |
4767 | The name of the \fIev.h\fR header file used to include it. The default if |
4928 | The name of the \fIev.h\fR header file used to include it. The default if |
4768 | undefined is \f(CW"ev.h"\fR in \fIevent.h\fR, \fIev.c\fR and \fIev++.h\fR. This can be |
4929 | undefined is \f(CW"ev.h"\fR in \fIevent.h\fR, \fIev.c\fR and \fIev++.h\fR. This can be |
4769 | used to virtually rename the \fIev.h\fR header file in case of conflicts. |
4930 | used to virtually rename the \fIev.h\fR header file in case of conflicts. |
4770 | .IP "\s-1EV_CONFIG_H \s0(h)" 4 |
4931 | .IP "\s-1EV_CONFIG_H\s0 (h)" 4 |
4771 | .IX Item "EV_CONFIG_H (h)" |
4932 | .IX Item "EV_CONFIG_H (h)" |
4772 | If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override |
4933 | If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override |
4773 | \&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to |
4934 | \&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to |
4774 | \&\f(CW\*(C`EV_H\*(C'\fR, above. |
4935 | \&\f(CW\*(C`EV_H\*(C'\fR, above. |
4775 | .IP "\s-1EV_EVENT_H \s0(h)" 4 |
4936 | .IP "\s-1EV_EVENT_H\s0 (h)" 4 |
4776 | .IX Item "EV_EVENT_H (h)" |
4937 | .IX Item "EV_EVENT_H (h)" |
4777 | Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea |
4938 | Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea |
4778 | of how the \fIevent.h\fR header can be found, the default is \f(CW"event.h"\fR. |
4939 | of how the \fIevent.h\fR header can be found, the default is \f(CW"event.h"\fR. |
4779 | .IP "\s-1EV_PROTOTYPES \s0(h)" 4 |
4940 | .IP "\s-1EV_PROTOTYPES\s0 (h)" 4 |
4780 | .IX Item "EV_PROTOTYPES (h)" |
4941 | .IX Item "EV_PROTOTYPES (h)" |
4781 | If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function |
4942 | If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function |
4782 | prototypes, but still define all the structs and other symbols. This is |
4943 | prototypes, but still define all the structs and other symbols. This is |
4783 | occasionally useful if you want to provide your own wrapper functions |
4944 | occasionally useful if you want to provide your own wrapper functions |
4784 | around libev functions. |
4945 | around libev functions. |
… | |
… | |
4977 | 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 |
4978 | 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 |
4979 | verification code will be called very frequently, which will slow down |
5140 | verification code will be called very frequently, which will slow down |
4980 | libev considerably. |
5141 | libev considerably. |
4981 | .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 |
4982 | 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 |
4983 | will be \f(CW0\fR. |
5147 | will be \f(CW0\fR. |
4984 | .IP "\s-1EV_COMMON\s0" 4 |
5148 | .IP "\s-1EV_COMMON\s0" 4 |
4985 | .IX Item "EV_COMMON" |
5149 | .IX Item "EV_COMMON" |
4986 | 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 |
… | |
… | |
4993 | .Vb 3 |
5157 | .Vb 3 |
4994 | \& #define EV_COMMON \e |
5158 | \& #define EV_COMMON \e |
4995 | \& SV *self; /* contains this struct */ \e |
5159 | \& SV *self; /* contains this struct */ \e |
4996 | \& SV *cb_sv, *fh /* note no trailing ";" */ |
5160 | \& SV *cb_sv, *fh /* note no trailing ";" */ |
4997 | .Ve |
5161 | .Ve |
4998 | .IP "\s-1EV_CB_DECLARE \s0(type)" 4 |
5162 | .IP "\s-1EV_CB_DECLARE\s0 (type)" 4 |
4999 | .IX Item "EV_CB_DECLARE (type)" |
5163 | .IX Item "EV_CB_DECLARE (type)" |
5000 | .PD 0 |
5164 | .PD 0 |
5001 | .IP "\s-1EV_CB_INVOKE \s0(watcher, revents)" 4 |
5165 | .IP "\s-1EV_CB_INVOKE\s0 (watcher, revents)" 4 |
5002 | .IX Item "EV_CB_INVOKE (watcher, revents)" |
5166 | .IX Item "EV_CB_INVOKE (watcher, revents)" |
5003 | .IP "ev_set_cb (ev, cb)" 4 |
5167 | .IP "ev_set_cb (ev, cb)" 4 |
5004 | .IX Item "ev_set_cb (ev, cb)" |
5168 | .IX Item "ev_set_cb (ev, cb)" |
5005 | .PD |
5169 | .PD |
5006 | Can be used to change the callback member declaration in each watcher, |
5170 | Can be used to change the callback member declaration in each watcher, |
… | |
… | |
5009 | their default definitions. One possible use for overriding these is to |
5173 | their default definitions. One possible use for overriding these is to |
5010 | 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 |
5011 | method calls instead of plain function calls in \*(C+. |
5175 | method calls instead of plain function calls in \*(C+. |
5012 | .SS "\s-1EXPORTED API SYMBOLS\s0" |
5176 | .SS "\s-1EXPORTED API SYMBOLS\s0" |
5013 | .IX Subsection "EXPORTED API SYMBOLS" |
5177 | .IX Subsection "EXPORTED API SYMBOLS" |
5014 | 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 |
5015 | 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 |
5016 | all public symbols, one per line: |
5180 | all public symbols, one per line: |
5017 | .PP |
5181 | .PP |
5018 | .Vb 2 |
5182 | .Vb 2 |
5019 | \& Symbols.ev for libev proper |
5183 | \& Symbols.ev for libev proper |
… | |
… | |
5251 | .PP |
5415 | .PP |
5252 | \fI\f(CI\*(C`select\*(C'\fI is buggy\fR |
5416 | \fI\f(CI\*(C`select\*(C'\fI is buggy\fR |
5253 | .IX Subsection "select is buggy" |
5417 | .IX Subsection "select is buggy" |
5254 | .PP |
5418 | .PP |
5255 | 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 |
5256 | 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 |
5257 | 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 |
5258 | you use more. |
5422 | you use more. |
5259 | .PP |
5423 | .PP |
5260 | There is an undocumented \*(L"workaround\*(R" for this \- defining |
5424 | There is an undocumented \*(L"workaround\*(R" for this \- defining |
5261 | \&\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 |
… | |
… | |
5409 | 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 |
5410 | structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO C\s0 for example), but it also |
5574 | structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO C\s0 for example), but it also |
5411 | 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 |
5412 | callback: The watcher callbacks have different type signatures, but libev |
5576 | callback: The watcher callbacks have different type signatures, but libev |
5413 | 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. |
5414 | .IP "pointer accesses must be thread-atomic" 4 |
5582 | .IP "pointer accesses must be thread-atomic" 4 |
5415 | .IX Item "pointer accesses must be thread-atomic" |
5583 | .IX Item "pointer accesses must be thread-atomic" |
5416 | 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 |
5417 | 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. |
5418 | .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 |