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135 | .IX Title "LIBEV 3" |
135 | .IX Title "LIBEV 3" |
136 | .TH LIBEV 3 "2013-10-29" "libev-4.15" "libev - high performance full featured event loop" |
136 | .TH LIBEV 3 "2023-05-15" "libev-4.33" "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 |
… | |
… | |
722 | 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 |
723 | immensely. |
802 | immensely. |
724 | .ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 |
803 | .ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 |
725 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
804 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
726 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
805 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
727 | 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 |
728 | it's really slow, but it still scales very well (O(active_fds)). |
807 | Solaris, it's really slow, but it still scales very well (O(active_fds)). |
729 | .Sp |
808 | .Sp |
730 | 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 |
731 | 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 |
732 | descriptors a \*(L"slow\*(R" \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR backend |
811 | descriptors a \*(L"slow\*(R" \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR backend |
733 | might perform better. |
812 | might perform better. |
… | |
… | |
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 |
… | |
… | |
810 | 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. |
811 | 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 |
812 | and \f(CW\*(C`ev_loop_destroy\*(C'\fR. |
899 | and \f(CW\*(C`ev_loop_destroy\*(C'\fR. |
813 | .IP "ev_loop_fork (loop)" 4 |
900 | .IP "ev_loop_fork (loop)" 4 |
814 | .IX Item "ev_loop_fork (loop)" |
901 | .IX Item "ev_loop_fork (loop)" |
815 | 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 |
816 | reinitialise the kernel state for backends that have one. Despite the |
903 | to reinitialise the kernel state for backends that have one. Despite |
817 | 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 |
818 | 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 |
819 | 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. |
|
|
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. |
820 | .Sp |
911 | .Sp |
821 | 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 |
822 | 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 |
823 | because some kernel interfaces *cough* \fIkqueue\fR *cough* do funny things |
914 | because some kernel interfaces *cough* \fIkqueue\fR *cough* do funny things |
824 | during fork. |
915 | during fork. |
… | |
… | |
996 | \& \- Queue all expired timers. |
1087 | \& \- Queue all expired timers. |
997 | \& \- Queue all expired periodics. |
1088 | \& \- Queue all expired periodics. |
998 | \& \- Queue all idle watchers with priority higher than that of pending events. |
1089 | \& \- Queue all idle watchers with priority higher than that of pending events. |
999 | \& \- Queue all check watchers. |
1090 | \& \- Queue all check watchers. |
1000 | \& \- Call all queued watchers in reverse order (i.e. check watchers first). |
1091 | \& \- Call all queued watchers in reverse order (i.e. check watchers first). |
1001 | \& Signals and child watchers are implemented as I/O watchers, and will |
1092 | \& Signals, async and child watchers are implemented as I/O watchers, and |
1002 | \& be handled here by queueing them when their watcher gets executed. |
1093 | \& will be handled here by queueing them when their watcher gets executed. |
1003 | \& \- If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT |
1094 | \& \- If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT |
1004 | \& were used, or there are no active watchers, goto FINISH, otherwise |
1095 | \& were used, or there are no active watchers, goto FINISH, otherwise |
1005 | \& continue with step LOOP. |
1096 | \& continue with step LOOP. |
1006 | \& FINISH: |
1097 | \& FINISH: |
1007 | \& \- Reset the ev_break status iff it was EVBREAK_ONE. |
1098 | \& \- Reset the ev_break status iff it was EVBREAK_ONE. |
… | |
… | |
1258 | with a watcher-specific start function (\f(CW\*(C`ev_TYPE_start (loop, watcher |
1349 | with a watcher-specific start function (\f(CW\*(C`ev_TYPE_start (loop, watcher |
1259 | *)\*(C'\fR), and you can stop watching for events at any time by calling the |
1350 | *)\*(C'\fR), and you can stop watching for events at any time by calling the |
1260 | corresponding stop function (\f(CW\*(C`ev_TYPE_stop (loop, watcher *)\*(C'\fR. |
1351 | corresponding stop function (\f(CW\*(C`ev_TYPE_stop (loop, watcher *)\*(C'\fR. |
1261 | .PP |
1352 | .PP |
1262 | As long as your watcher is active (has been started but not stopped) you |
1353 | As long as your watcher is active (has been started but not stopped) you |
1263 | must not touch the values stored in it. Most specifically you must never |
1354 | must not touch the values stored in it except when explicitly documented |
1264 | reinitialise it or call its \f(CW\*(C`ev_TYPE_set\*(C'\fR macro. |
1355 | otherwise. Most specifically you must never reinitialise it or call its |
|
|
1356 | \&\f(CW\*(C`ev_TYPE_set\*(C'\fR macro. |
1265 | .PP |
1357 | .PP |
1266 | Each and every callback receives the event loop pointer as first, the |
1358 | Each and every callback receives the event loop pointer as first, the |
1267 | registered watcher structure as second, and a bitset of received events as |
1359 | registered watcher structure as second, and a bitset of received events as |
1268 | third argument. |
1360 | third argument. |
1269 | .PP |
1361 | .PP |
… | |
… | |
1360 | bug in your program. |
1452 | bug in your program. |
1361 | .Sp |
1453 | .Sp |
1362 | Libev will usually signal a few \*(L"dummy\*(R" events together with an error, for |
1454 | Libev will usually signal a few \*(L"dummy\*(R" events together with an error, for |
1363 | example it might indicate that a fd is readable or writable, and if your |
1455 | example it might indicate that a fd is readable or writable, and if your |
1364 | callbacks is well-written it can just attempt the operation and cope with |
1456 | callbacks is well-written it can just attempt the operation and cope with |
1365 | the error from \fIread()\fR or \fIwrite()\fR. This will not work in multi-threaded |
1457 | the error from \fBread()\fR or \fBwrite()\fR. This will not work in multi-threaded |
1366 | programs, though, as the fd could already be closed and reused for another |
1458 | programs, though, as the fd could already be closed and reused for another |
1367 | thing, so beware. |
1459 | thing, so beware. |
1368 | .SS "\s-1GENERIC WATCHER FUNCTIONS\s0" |
1460 | .SS "\s-1GENERIC WATCHER FUNCTIONS\s0" |
1369 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
1461 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
1370 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
1462 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
… | |
… | |
1440 | therefore a good idea to always call its \f(CW\*(C`ev_TYPE_stop\*(C'\fR function. |
1532 | therefore a good idea to always call its \f(CW\*(C`ev_TYPE_stop\*(C'\fR function. |
1441 | .IP "bool ev_is_active (ev_TYPE *watcher)" 4 |
1533 | .IP "bool ev_is_active (ev_TYPE *watcher)" 4 |
1442 | .IX Item "bool ev_is_active (ev_TYPE *watcher)" |
1534 | .IX Item "bool ev_is_active (ev_TYPE *watcher)" |
1443 | Returns a true value iff the watcher is active (i.e. it has been started |
1535 | Returns a true value iff the watcher is active (i.e. it has been started |
1444 | and not yet been stopped). As long as a watcher is active you must not modify |
1536 | and not yet been stopped). As long as a watcher is active you must not modify |
1445 | it. |
1537 | it unless documented otherwise. |
|
|
1538 | .Sp |
|
|
1539 | Obviously, it is safe to call this on an active watcher, or actually any |
|
|
1540 | watcher that is initialised. |
1446 | .IP "bool ev_is_pending (ev_TYPE *watcher)" 4 |
1541 | .IP "bool ev_is_pending (ev_TYPE *watcher)" 4 |
1447 | .IX Item "bool ev_is_pending (ev_TYPE *watcher)" |
1542 | .IX Item "bool ev_is_pending (ev_TYPE *watcher)" |
1448 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
1543 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
1449 | events but its callback has not yet been invoked). As long as a watcher |
1544 | events but its callback has not yet been invoked). As long as a watcher |
1450 | is pending (but not active) you must not call an init function on it (but |
1545 | is pending (but not active) you must not call an init function on it (but |
1451 | \&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe), you must not change its priority, and you must |
1546 | \&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe), you must not change its priority, and you must |
1452 | make sure the watcher is available to libev (e.g. you cannot \f(CW\*(C`free ()\*(C'\fR |
1547 | make sure the watcher is available to libev (e.g. you cannot \f(CW\*(C`free ()\*(C'\fR |
1453 | it). |
1548 | it). |
|
|
1549 | .Sp |
|
|
1550 | It is safe to call this on any watcher in any state as long as it is |
|
|
1551 | initialised. |
1454 | .IP "callback ev_cb (ev_TYPE *watcher)" 4 |
1552 | .IP "callback ev_cb (ev_TYPE *watcher)" 4 |
1455 | .IX Item "callback ev_cb (ev_TYPE *watcher)" |
1553 | .IX Item "callback ev_cb (ev_TYPE *watcher)" |
1456 | Returns the callback currently set on the watcher. |
1554 | Returns the callback currently set on the watcher. |
1457 | .IP "ev_set_cb (ev_TYPE *watcher, callback)" 4 |
1555 | .IP "ev_set_cb (ev_TYPE *watcher, callback)" 4 |
1458 | .IX Item "ev_set_cb (ev_TYPE *watcher, callback)" |
1556 | .IX Item "ev_set_cb (ev_TYPE *watcher, callback)" |
… | |
… | |
1471 | from being executed (except for \f(CW\*(C`ev_idle\*(C'\fR watchers). |
1569 | from being executed (except for \f(CW\*(C`ev_idle\*(C'\fR watchers). |
1472 | .Sp |
1570 | .Sp |
1473 | If you need to suppress invocation when higher priority events are pending |
1571 | If you need to suppress invocation when higher priority events are pending |
1474 | you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality. |
1572 | you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality. |
1475 | .Sp |
1573 | .Sp |
1476 | You \fImust not\fR change the priority of a watcher as long as it is active or |
1574 | You \fImust not\fR change the priority of a watcher as long as it is active |
1477 | pending. |
1575 | or pending. Reading the priority with \f(CW\*(C`ev_priority\*(C'\fR is fine in any state. |
1478 | .Sp |
1576 | .Sp |
1479 | Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is |
1577 | Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is |
1480 | fine, as long as you do not mind that the priority value you query might |
1578 | fine, as long as you do not mind that the priority value you query might |
1481 | or might not have been clamped to the valid range. |
1579 | or might not have been clamped to the valid range. |
1482 | .Sp |
1580 | .Sp |
… | |
… | |
1501 | callback to be invoked, which can be accomplished with this function. |
1599 | callback to be invoked, which can be accomplished with this function. |
1502 | .IP "ev_feed_event (loop, ev_TYPE *watcher, int revents)" 4 |
1600 | .IP "ev_feed_event (loop, ev_TYPE *watcher, int revents)" 4 |
1503 | .IX Item "ev_feed_event (loop, ev_TYPE *watcher, int revents)" |
1601 | .IX Item "ev_feed_event (loop, ev_TYPE *watcher, int revents)" |
1504 | Feeds the given event set into the event loop, as if the specified event |
1602 | Feeds the given event set into the event loop, as if the specified event |
1505 | had happened for the specified watcher (which must be a pointer to an |
1603 | had happened for the specified watcher (which must be a pointer to an |
1506 | initialised but not necessarily started event watcher). Obviously you must |
1604 | initialised but not necessarily started event watcher, though it can be |
1507 | not free the watcher as long as it has pending events. |
1605 | active). Obviously you must not free the watcher as long as it has pending |
|
|
1606 | events. |
1508 | .Sp |
1607 | .Sp |
1509 | Stopping the watcher, letting libev invoke it, or calling |
1608 | Stopping the watcher, letting libev invoke it, or calling |
1510 | \&\f(CW\*(C`ev_clear_pending\*(C'\fR will clear the pending event, even if the watcher was |
1609 | \&\f(CW\*(C`ev_clear_pending\*(C'\fR will clear the pending event, even if the watcher was |
1511 | not started in the first place. |
1610 | not started in the first place. |
1512 | .Sp |
1611 | .Sp |
… | |
… | |
1533 | \&\f(CW\*(C`ev_TYPE_init\*(C'\fR again. |
1632 | \&\f(CW\*(C`ev_TYPE_init\*(C'\fR again. |
1534 | .IP "started/running/active" 4 |
1633 | .IP "started/running/active" 4 |
1535 | .IX Item "started/running/active" |
1634 | .IX Item "started/running/active" |
1536 | Once a watcher has been started with a call to \f(CW\*(C`ev_TYPE_start\*(C'\fR it becomes |
1635 | Once a watcher has been started with a call to \f(CW\*(C`ev_TYPE_start\*(C'\fR it becomes |
1537 | property of the event loop, and is actively waiting for events. While in |
1636 | property of the event loop, and is actively waiting for events. While in |
1538 | this state it cannot be accessed (except in a few documented ways), moved, |
1637 | this state it cannot be accessed (except in a few documented ways, such as |
1539 | freed or anything else \- the only legal thing is to keep a pointer to it, |
1638 | stoping it), moved, freed or anything else \- the only legal thing is to |
1540 | and call libev functions on it that are documented to work on active watchers. |
1639 | keep a pointer to it, and call libev functions on it that are documented |
|
|
1640 | to work on active watchers. |
|
|
1641 | .Sp |
|
|
1642 | As a rule of thumb, before accessing a member or calling any function on |
|
|
1643 | a watcher, it should be stopped (or freshly initialised). If that is not |
|
|
1644 | convenient, you can check the documentation for that function or member to |
|
|
1645 | see if it is safe to use on an active watcher. |
1541 | .IP "pending" 4 |
1646 | .IP "pending" 4 |
1542 | .IX Item "pending" |
1647 | .IX Item "pending" |
1543 | If a watcher is active and libev determines that an event it is interested |
1648 | If a watcher is active and libev determines that an event it is interested |
1544 | in has occurred (such as a timer expiring), it will become pending. It will |
1649 | in has occurred (such as a timer expiring), it will become pending. It |
1545 | stay in this pending state until either it is stopped or its callback is |
1650 | will stay in this pending state until either it is explicitly stopped or |
1546 | about to be invoked, so it is not normally pending inside the watcher |
1651 | its callback is about to be invoked, so it is not normally pending inside |
1547 | callback. |
1652 | the watcher callback. |
1548 | .Sp |
1653 | .Sp |
1549 | The watcher might or might not be active while it is pending (for example, |
1654 | Generally, the watcher might or might not be active while it is pending |
1550 | an expired non-repeating timer can be pending but no longer active). If it |
1655 | (for example, an expired non-repeating timer can be pending but no longer |
1551 | is stopped, it can be freely accessed (e.g. by calling \f(CW\*(C`ev_TYPE_set\*(C'\fR), |
1656 | active). If it is pending but not active, it can be freely accessed (e.g. |
1552 | but it is still property of the event loop at this time, so cannot be |
1657 | by calling \f(CW\*(C`ev_TYPE_set\*(C'\fR), but it is still property of the event loop at |
1553 | moved, freed or reused. And if it is active the rules described in the |
1658 | this time, so cannot be moved, freed or reused. And if it is active the |
1554 | previous item still apply. |
1659 | rules described in the previous item still apply. |
|
|
1660 | .Sp |
|
|
1661 | Explicitly stopping a watcher will also clear the pending state |
|
|
1662 | unconditionally, so it is safe to stop a watcher and then free it. |
1555 | .Sp |
1663 | .Sp |
1556 | It is also possible to feed an event on a watcher that is not active (e.g. |
1664 | It is also possible to feed an event on a watcher that is not active (e.g. |
1557 | via \f(CW\*(C`ev_feed_event\*(C'\fR), in which case it becomes pending without being |
1665 | via \f(CW\*(C`ev_feed_event\*(C'\fR), in which case it becomes pending without being |
1558 | active. |
1666 | active. |
1559 | .IP "stopped" 4 |
1667 | .IP "stopped" 4 |
… | |
… | |
1572 | .IX Subsection "WATCHER PRIORITY MODELS" |
1680 | .IX Subsection "WATCHER PRIORITY MODELS" |
1573 | Many event loops support \fIwatcher priorities\fR, which are usually small |
1681 | Many event loops support \fIwatcher priorities\fR, which are usually small |
1574 | integers that influence the ordering of event callback invocation |
1682 | integers that influence the ordering of event callback invocation |
1575 | between watchers in some way, all else being equal. |
1683 | between watchers in some way, all else being equal. |
1576 | .PP |
1684 | .PP |
1577 | In libev, Watcher priorities can be set using \f(CW\*(C`ev_set_priority\*(C'\fR. See its |
1685 | In libev, watcher priorities can be set using \f(CW\*(C`ev_set_priority\*(C'\fR. See its |
1578 | description for the more technical details such as the actual priority |
1686 | description for the more technical details such as the actual priority |
1579 | range. |
1687 | range. |
1580 | .PP |
1688 | .PP |
1581 | There are two common ways how these these priorities are being interpreted |
1689 | There are two common ways how these these priorities are being interpreted |
1582 | by event loops: |
1690 | by event loops: |
… | |
… | |
1676 | .IX Header "WATCHER TYPES" |
1784 | .IX Header "WATCHER TYPES" |
1677 | This section describes each watcher in detail, but will not repeat |
1785 | This section describes each watcher in detail, but will not repeat |
1678 | information given in the last section. Any initialisation/set macros, |
1786 | information given in the last section. Any initialisation/set macros, |
1679 | functions and members specific to the watcher type are explained. |
1787 | functions and members specific to the watcher type are explained. |
1680 | .PP |
1788 | .PP |
1681 | Members are additionally marked with either \fI[read\-only]\fR, meaning that, |
1789 | Most members are additionally marked with either \fI[read\-only]\fR, meaning |
1682 | while the watcher is active, you can look at the member and expect some |
1790 | that, while the watcher is active, you can look at the member and expect |
1683 | sensible content, but you must not modify it (you can modify it while the |
1791 | some sensible content, but you must not modify it (you can modify it while |
1684 | watcher is stopped to your hearts content), or \fI[read\-write]\fR, which |
1792 | the watcher is stopped to your hearts content), or \fI[read\-write]\fR, which |
1685 | means you can expect it to have some sensible content while the watcher |
1793 | means you can expect it to have some sensible content while the watcher is |
1686 | is active, but you can also modify it. Modifying it may not do something |
1794 | active, but you can also modify it (within the same thread as the event |
|
|
1795 | loop, i.e. without creating data races). Modifying it may not do something |
1687 | sensible or take immediate effect (or do anything at all), but libev will |
1796 | sensible or take immediate effect (or do anything at all), but libev will |
1688 | not crash or malfunction in any way. |
1797 | not crash or malfunction in any way. |
|
|
1798 | .PP |
|
|
1799 | In any case, the documentation for each member will explain what the |
|
|
1800 | effects are, and if there are any additional access restrictions. |
1689 | .ie n .SS """ev_io"" \- is this file descriptor readable or writable?" |
1801 | .ie n .SS """ev_io"" \- is this file descriptor readable or writable?" |
1690 | .el .SS "\f(CWev_io\fP \- is this file descriptor readable or writable?" |
1802 | .el .SS "\f(CWev_io\fP \- is this file descriptor readable or writable?" |
1691 | .IX Subsection "ev_io - is this file descriptor readable or writable?" |
1803 | .IX Subsection "ev_io - is this file descriptor readable or writable?" |
1692 | I/O watchers check whether a file descriptor is readable or writable |
1804 | I/O watchers check whether a file descriptor is readable or writable |
1693 | in each iteration of the event loop, or, more precisely, when reading |
1805 | in each iteration of the event loop, or, more precisely, when reading |
… | |
… | |
1721 | But really, best use non-blocking mode. |
1833 | But really, best use non-blocking mode. |
1722 | .PP |
1834 | .PP |
1723 | \fIThe special problem of disappearing file descriptors\fR |
1835 | \fIThe special problem of disappearing file descriptors\fR |
1724 | .IX Subsection "The special problem of disappearing file descriptors" |
1836 | .IX Subsection "The special problem of disappearing file descriptors" |
1725 | .PP |
1837 | .PP |
1726 | Some backends (e.g. kqueue, epoll) need to be told about closing a file |
1838 | Some backends (e.g. kqueue, epoll, linuxaio) need to be told about closing |
1727 | descriptor (either due to calling \f(CW\*(C`close\*(C'\fR explicitly or any other means, |
1839 | a file descriptor (either due to calling \f(CW\*(C`close\*(C'\fR explicitly or any other |
1728 | such as \f(CW\*(C`dup2\*(C'\fR). The reason is that you register interest in some file |
1840 | means, such as \f(CW\*(C`dup2\*(C'\fR). The reason is that you register interest in some |
1729 | descriptor, but when it goes away, the operating system will silently drop |
1841 | file descriptor, but when it goes away, the operating system will silently |
1730 | this interest. If another file descriptor with the same number then is |
1842 | drop this interest. If another file descriptor with the same number then |
1731 | registered with libev, there is no efficient way to see that this is, in |
1843 | is registered with libev, there is no efficient way to see that this is, |
1732 | fact, a different file descriptor. |
1844 | in fact, a different file descriptor. |
1733 | .PP |
1845 | .PP |
1734 | To avoid having to explicitly tell libev about such cases, libev follows |
1846 | To avoid having to explicitly tell libev about such cases, libev follows |
1735 | the following policy: Each time \f(CW\*(C`ev_io_set\*(C'\fR is being called, libev |
1847 | the following policy: Each time \f(CW\*(C`ev_io_set\*(C'\fR is being called, libev |
1736 | will assume that this is potentially a new file descriptor, otherwise |
1848 | will assume that this is potentially a new file descriptor, otherwise |
1737 | it is assumed that the file descriptor stays the same. That means that |
1849 | it is assumed that the file descriptor stays the same. That means that |
… | |
… | |
1789 | reuse the same code path. |
1901 | reuse the same code path. |
1790 | .PP |
1902 | .PP |
1791 | \fIThe special problem of fork\fR |
1903 | \fIThe special problem of fork\fR |
1792 | .IX Subsection "The special problem of fork" |
1904 | .IX Subsection "The special problem of fork" |
1793 | .PP |
1905 | .PP |
1794 | Some backends (epoll, kqueue) do not support \f(CW\*(C`fork ()\*(C'\fR at all or exhibit |
1906 | Some backends (epoll, kqueue, linuxaio, iouring) do not support \f(CW\*(C`fork ()\*(C'\fR |
1795 | useless behaviour. Libev fully supports fork, but needs to be told about |
1907 | at all or exhibit useless behaviour. Libev fully supports fork, but needs |
1796 | it in the child if you want to continue to use it in the child. |
1908 | to be told about it in the child if you want to continue to use it in the |
|
|
1909 | child. |
1797 | .PP |
1910 | .PP |
1798 | To support fork in your child processes, you have to call \f(CW\*(C`ev_loop_fork |
1911 | To support fork in your child processes, you have to call \f(CW\*(C`ev_loop_fork |
1799 | ()\*(C'\fR after a fork in the child, enable \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR, or resort to |
1912 | ()\*(C'\fR after a fork in the child, enable \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR, or resort to |
1800 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
1913 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
1801 | .PP |
1914 | .PP |
… | |
… | |
1806 | when writing to a pipe whose other end has been closed, your program gets |
1919 | when writing to a pipe whose other end has been closed, your program gets |
1807 | sent a \s-1SIGPIPE,\s0 which, by default, aborts your program. For most programs |
1920 | sent a \s-1SIGPIPE,\s0 which, by default, aborts your program. For most programs |
1808 | this is sensible behaviour, for daemons, this is usually undesirable. |
1921 | this is sensible behaviour, for daemons, this is usually undesirable. |
1809 | .PP |
1922 | .PP |
1810 | So when you encounter spurious, unexplained daemon exits, make sure you |
1923 | So when you encounter spurious, unexplained daemon exits, make sure you |
1811 | ignore \s-1SIGPIPE \s0(and maybe make sure you log the exit status of your daemon |
1924 | ignore \s-1SIGPIPE\s0 (and maybe make sure you log the exit status of your daemon |
1812 | somewhere, as that would have given you a big clue). |
1925 | somewhere, as that would have given you a big clue). |
1813 | .PP |
1926 | .PP |
1814 | \fIThe special problem of \fIaccept()\fIing when you can't\fR |
1927 | \fIThe special problem of \f(BIaccept()\fIing when you can't\fR |
1815 | .IX Subsection "The special problem of accept()ing when you can't" |
1928 | .IX Subsection "The special problem of accept()ing when you can't" |
1816 | .PP |
1929 | .PP |
1817 | Many implementations of the \s-1POSIX \s0\f(CW\*(C`accept\*(C'\fR function (for example, |
1930 | Many implementations of the \s-1POSIX\s0 \f(CW\*(C`accept\*(C'\fR function (for example, |
1818 | found in post\-2004 Linux) have the peculiar behaviour of not removing a |
1931 | found in post\-2004 Linux) have the peculiar behaviour of not removing a |
1819 | connection from the pending queue in all error cases. |
1932 | connection from the pending queue in all error cases. |
1820 | .PP |
1933 | .PP |
1821 | For example, larger servers often run out of file descriptors (because |
1934 | For example, larger servers often run out of file descriptors (because |
1822 | of resource limits), causing \f(CW\*(C`accept\*(C'\fR to fail with \f(CW\*(C`ENFILE\*(C'\fR but not |
1935 | of resource limits), causing \f(CW\*(C`accept\*(C'\fR to fail with \f(CW\*(C`ENFILE\*(C'\fR but not |
… | |
… | |
1858 | .PD 0 |
1971 | .PD 0 |
1859 | .IP "ev_io_set (ev_io *, int fd, int events)" 4 |
1972 | .IP "ev_io_set (ev_io *, int fd, int events)" 4 |
1860 | .IX Item "ev_io_set (ev_io *, int fd, int events)" |
1973 | .IX Item "ev_io_set (ev_io *, int fd, int events)" |
1861 | .PD |
1974 | .PD |
1862 | Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The \f(CW\*(C`fd\*(C'\fR is the file descriptor to |
1975 | Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The \f(CW\*(C`fd\*(C'\fR is the file descriptor to |
1863 | 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 |
1976 | 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, both |
1864 | \&\f(CW\*(C`EV_READ | EV_WRITE\*(C'\fR, to express the desire to receive the given events. |
1977 | \&\f(CW\*(C`EV_READ | EV_WRITE\*(C'\fR or \f(CW0\fR, to express the desire to receive the given |
|
|
1978 | events. |
|
|
1979 | .Sp |
|
|
1980 | Note that setting the \f(CW\*(C`events\*(C'\fR to \f(CW0\fR and starting the watcher is |
|
|
1981 | supported, but not specially optimized \- if your program sometimes happens |
|
|
1982 | to generate this combination this is fine, but if it is easy to avoid |
|
|
1983 | starting an io watcher watching for no events you should do so. |
|
|
1984 | .IP "ev_io_modify (ev_io *, int events)" 4 |
|
|
1985 | .IX Item "ev_io_modify (ev_io *, int events)" |
|
|
1986 | Similar to \f(CW\*(C`ev_io_set\*(C'\fR, but only changes the requested events. Using this |
|
|
1987 | might be faster with some backends, as libev can assume that the \f(CW\*(C`fd\*(C'\fR |
|
|
1988 | still refers to the same underlying file description, something it cannot |
|
|
1989 | do when using \f(CW\*(C`ev_io_set\*(C'\fR. |
1865 | .IP "int fd [read\-only]" 4 |
1990 | .IP "int fd [no\-modify]" 4 |
1866 | .IX Item "int fd [read-only]" |
1991 | .IX Item "int fd [no-modify]" |
1867 | The file descriptor being watched. |
1992 | The file descriptor being watched. While it can be read at any time, you |
|
|
1993 | must not modify this member even when the watcher is stopped \- always use |
|
|
1994 | \&\f(CW\*(C`ev_io_set\*(C'\fR for that. |
1868 | .IP "int events [read\-only]" 4 |
1995 | .IP "int events [no\-modify]" 4 |
1869 | .IX Item "int events [read-only]" |
1996 | .IX Item "int events [no-modify]" |
1870 | The events being watched. |
1997 | The set of events the fd is being watched for, among other flags. Remember |
|
|
1998 | that this is a bit set \- to test for \f(CW\*(C`EV_READ\*(C'\fR, use \f(CW\*(C`w\->events & |
|
|
1999 | EV_READ\*(C'\fR, and similarly for \f(CW\*(C`EV_WRITE\*(C'\fR. |
|
|
2000 | .Sp |
|
|
2001 | As with \f(CW\*(C`fd\*(C'\fR, you must not modify this member even when the watcher is |
|
|
2002 | stopped, always use \f(CW\*(C`ev_io_set\*(C'\fR or \f(CW\*(C`ev_io_modify\*(C'\fR for that. |
1871 | .PP |
2003 | .PP |
1872 | \fIExamples\fR |
2004 | \fIExamples\fR |
1873 | .IX Subsection "Examples" |
2005 | .IX Subsection "Examples" |
1874 | .PP |
2006 | .PP |
1875 | Example: Call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well |
2007 | Example: Call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well |
… | |
… | |
2161 | .PP |
2293 | .PP |
2162 | The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR |
2294 | The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR |
2163 | time. This is usually the right thing as this timestamp refers to the time |
2295 | time. This is usually the right thing as this timestamp refers to the time |
2164 | of the event triggering whatever timeout you are modifying/starting. If |
2296 | of the event triggering whatever timeout you are modifying/starting. If |
2165 | you suspect event processing to be delayed and you \fIneed\fR to base the |
2297 | you suspect event processing to be delayed and you \fIneed\fR to base the |
2166 | timeout on the current time, use something like this to adjust for this: |
2298 | timeout on the current time, use something like the following to adjust |
|
|
2299 | for it: |
2167 | .PP |
2300 | .PP |
2168 | .Vb 1 |
2301 | .Vb 1 |
2169 | \& ev_timer_set (&timer, after + ev_now () \- ev_time (), 0.); |
2302 | \& ev_timer_set (&timer, after + (ev_time () \- ev_now ()), 0.); |
2170 | .Ve |
2303 | .Ve |
2171 | .PP |
2304 | .PP |
2172 | If the event loop is suspended for a long time, you can also force an |
2305 | If the event loop is suspended for a long time, you can also force an |
2173 | update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update |
2306 | update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update |
2174 | ()\*(C'\fR. |
2307 | ()\*(C'\fR, although that will push the event time of all outstanding events |
|
|
2308 | further into the future. |
2175 | .PP |
2309 | .PP |
2176 | \fIThe special problem of unsynchronised clocks\fR |
2310 | \fIThe special problem of unsynchronised clocks\fR |
2177 | .IX Subsection "The special problem of unsynchronised clocks" |
2311 | .IX Subsection "The special problem of unsynchronised clocks" |
2178 | .PP |
2312 | .PP |
2179 | Modern systems have a variety of clocks \- libev itself uses the normal |
2313 | Modern systems have a variety of clocks \- libev itself uses the normal |
… | |
… | |
2244 | .IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" |
2378 | .IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" |
2245 | .PD 0 |
2379 | .PD 0 |
2246 | .IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4 |
2380 | .IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4 |
2247 | .IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" |
2381 | .IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" |
2248 | .PD |
2382 | .PD |
2249 | Configure the timer to trigger after \f(CW\*(C`after\*(C'\fR seconds. If \f(CW\*(C`repeat\*(C'\fR |
2383 | Configure the timer to trigger after \f(CW\*(C`after\*(C'\fR seconds (fractional and |
2250 | is \f(CW0.\fR, then it will automatically be stopped once the timeout is |
2384 | negative values are supported). If \f(CW\*(C`repeat\*(C'\fR is \f(CW0.\fR, then it will |
2251 | reached. If it is positive, then the timer will automatically be |
2385 | automatically be stopped once the timeout is reached. If it is positive, |
2252 | configured to trigger again \f(CW\*(C`repeat\*(C'\fR seconds later, again, and again, |
2386 | then the timer will automatically be configured to trigger again \f(CW\*(C`repeat\*(C'\fR |
2253 | until stopped manually. |
2387 | seconds later, again, and again, until stopped manually. |
2254 | .Sp |
2388 | .Sp |
2255 | The timer itself will do a best-effort at avoiding drift, that is, if |
2389 | The timer itself will do a best-effort at avoiding drift, that is, if |
2256 | you configure a timer to trigger every 10 seconds, then it will normally |
2390 | you configure a timer to trigger every 10 seconds, then it will normally |
2257 | trigger at exactly 10 second intervals. If, however, your program cannot |
2391 | trigger at exactly 10 second intervals. If, however, your program cannot |
2258 | keep up with the timer (because it takes longer than those 10 seconds to |
2392 | keep up with the timer (because it takes longer than those 10 seconds to |
… | |
… | |
2340 | Periodic watchers are also timers of a kind, but they are very versatile |
2474 | Periodic watchers are also timers of a kind, but they are very versatile |
2341 | (and unfortunately a bit complex). |
2475 | (and unfortunately a bit complex). |
2342 | .PP |
2476 | .PP |
2343 | Unlike \f(CW\*(C`ev_timer\*(C'\fR, periodic watchers are not based on real time (or |
2477 | Unlike \f(CW\*(C`ev_timer\*(C'\fR, periodic watchers are not based on real time (or |
2344 | relative time, the physical time that passes) but on wall clock time |
2478 | relative time, the physical time that passes) but on wall clock time |
2345 | (absolute time, the thing you can read on your calender or clock). The |
2479 | (absolute time, the thing you can read on your calendar or clock). The |
2346 | difference is that wall clock time can run faster or slower than real |
2480 | difference is that wall clock time can run faster or slower than real |
2347 | time, and time jumps are not uncommon (e.g. when you adjust your |
2481 | time, and time jumps are not uncommon (e.g. when you adjust your |
2348 | wrist-watch). |
2482 | wrist-watch). |
2349 | .PP |
2483 | .PP |
2350 | You can tell a periodic watcher to trigger after some specific point |
2484 | You can tell a periodic watcher to trigger after some specific point |
… | |
… | |
2355 | \&\f(CW\*(C`ev_timer\*(C'\fR, which would still trigger roughly 10 seconds after starting |
2489 | \&\f(CW\*(C`ev_timer\*(C'\fR, which would still trigger roughly 10 seconds after starting |
2356 | it, as it uses a relative timeout). |
2490 | it, as it uses a relative timeout). |
2357 | .PP |
2491 | .PP |
2358 | \&\f(CW\*(C`ev_periodic\*(C'\fR watchers can also be used to implement vastly more complex |
2492 | \&\f(CW\*(C`ev_periodic\*(C'\fR watchers can also be used to implement vastly more complex |
2359 | timers, such as triggering an event on each \*(L"midnight, local time\*(R", or |
2493 | timers, such as triggering an event on each \*(L"midnight, local time\*(R", or |
2360 | other complicated rules. This cannot be done with \f(CW\*(C`ev_timer\*(C'\fR watchers, as |
2494 | other complicated rules. This cannot easily be done with \f(CW\*(C`ev_timer\*(C'\fR |
2361 | those cannot react to time jumps. |
2495 | watchers, as those cannot react to time jumps. |
2362 | .PP |
2496 | .PP |
2363 | As with timers, the callback is guaranteed to be invoked only when the |
2497 | As with timers, the callback is guaranteed to be invoked only when the |
2364 | point in time where it is supposed to trigger has passed. If multiple |
2498 | point in time where it is supposed to trigger has passed. If multiple |
2365 | timers become ready during the same loop iteration then the ones with |
2499 | timers become ready during the same loop iteration then the ones with |
2366 | earlier time-out values are invoked before ones with later time-out values |
2500 | earlier time-out values are invoked before ones with later time-out values |
… | |
… | |
2427 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`offset\*(C'\fR are both being |
2561 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`offset\*(C'\fR are both being |
2428 | ignored. Instead, each time the periodic watcher gets scheduled, the |
2562 | ignored. Instead, each time the periodic watcher gets scheduled, the |
2429 | reschedule callback will be called with the watcher as first, and the |
2563 | reschedule callback will be called with the watcher as first, and the |
2430 | current time as second argument. |
2564 | current time as second argument. |
2431 | .Sp |
2565 | .Sp |
2432 | \&\s-1NOTE: \s0\fIThis callback \s-1MUST NOT\s0 stop or destroy any periodic watcher, ever, |
2566 | \&\s-1NOTE:\s0 \fIThis callback \s-1MUST NOT\s0 stop or destroy any periodic watcher, ever, |
2433 | or make \s-1ANY\s0 other event loop modifications whatsoever, unless explicitly |
2567 | or make \s-1ANY\s0 other event loop modifications whatsoever, unless explicitly |
2434 | allowed by documentation here\fR. |
2568 | allowed by documentation here\fR. |
2435 | .Sp |
2569 | .Sp |
2436 | If you need to stop it, return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop |
2570 | If you need to stop it, return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop |
2437 | it afterwards (e.g. by starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is the |
2571 | it afterwards (e.g. by starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is the |
… | |
… | |
2451 | It must return the next time to trigger, based on the passed time value |
2585 | It must return the next time to trigger, based on the passed time value |
2452 | (that is, the lowest time value larger than to the second argument). It |
2586 | (that is, the lowest time value larger than to the second argument). It |
2453 | will usually be called just before the callback will be triggered, but |
2587 | will usually be called just before the callback will be triggered, but |
2454 | might be called at other times, too. |
2588 | might be called at other times, too. |
2455 | .Sp |
2589 | .Sp |
2456 | \&\s-1NOTE: \s0\fIThis callback must always return a time that is higher than or |
2590 | \&\s-1NOTE:\s0 \fIThis callback must always return a time that is higher than or |
2457 | equal to the passed \f(CI\*(C`now\*(C'\fI value\fR. |
2591 | equal to the passed \f(CI\*(C`now\*(C'\fI value\fR. |
2458 | .Sp |
2592 | .Sp |
2459 | This can be used to create very complex timers, such as a timer that |
2593 | This can be used to create very complex timers, such as a timer that |
2460 | triggers on \*(L"next midnight, local time\*(R". To do this, you would calculate the |
2594 | triggers on \*(L"next midnight, local time\*(R". To do this, you would calculate |
2461 | next midnight after \f(CW\*(C`now\*(C'\fR and return the timestamp value for this. How |
2595 | the next midnight after \f(CW\*(C`now\*(C'\fR and return the timestamp value for |
2462 | you do this is, again, up to you (but it is not trivial, which is the main |
2596 | this. Here is a (completely untested, no error checking) example on how to |
2463 | reason I omitted it as an example). |
2597 | do this: |
|
|
2598 | .Sp |
|
|
2599 | .Vb 1 |
|
|
2600 | \& #include <time.h> |
|
|
2601 | \& |
|
|
2602 | \& static ev_tstamp |
|
|
2603 | \& my_rescheduler (ev_periodic *w, ev_tstamp now) |
|
|
2604 | \& { |
|
|
2605 | \& time_t tnow = (time_t)now; |
|
|
2606 | \& struct tm tm; |
|
|
2607 | \& localtime_r (&tnow, &tm); |
|
|
2608 | \& |
|
|
2609 | \& tm.tm_sec = tm.tm_min = tm.tm_hour = 0; // midnight current day |
|
|
2610 | \& ++tm.tm_mday; // midnight next day |
|
|
2611 | \& |
|
|
2612 | \& return mktime (&tm); |
|
|
2613 | \& } |
|
|
2614 | .Ve |
|
|
2615 | .Sp |
|
|
2616 | Note: this code might run into trouble on days that have more then two |
|
|
2617 | midnights (beginning and end). |
2464 | .RE |
2618 | .RE |
2465 | .RS 4 |
2619 | .RS 4 |
2466 | .RE |
2620 | .RE |
2467 | .IP "ev_periodic_again (loop, ev_periodic *)" 4 |
2621 | .IP "ev_periodic_again (loop, ev_periodic *)" 4 |
2468 | .IX Item "ev_periodic_again (loop, ev_periodic *)" |
2622 | .IX Item "ev_periodic_again (loop, ev_periodic *)" |
… | |
… | |
2553 | only within the same loop, i.e. you can watch for \f(CW\*(C`SIGINT\*(C'\fR in your |
2707 | only within the same loop, i.e. you can watch for \f(CW\*(C`SIGINT\*(C'\fR in your |
2554 | default loop and for \f(CW\*(C`SIGIO\*(C'\fR in another loop, but you cannot watch for |
2708 | default loop and for \f(CW\*(C`SIGIO\*(C'\fR in another loop, but you cannot watch for |
2555 | \&\f(CW\*(C`SIGINT\*(C'\fR in both the default loop and another loop at the same time. At |
2709 | \&\f(CW\*(C`SIGINT\*(C'\fR in both the default loop and another loop at the same time. At |
2556 | the moment, \f(CW\*(C`SIGCHLD\*(C'\fR is permanently tied to the default loop. |
2710 | the moment, \f(CW\*(C`SIGCHLD\*(C'\fR is permanently tied to the default loop. |
2557 | .PP |
2711 | .PP |
2558 | When the first watcher gets started will libev actually register something |
2712 | Only after the first watcher for a signal is started will libev actually |
2559 | with the kernel (thus it coexists with your own signal handlers as long as |
2713 | register something with the kernel. It thus coexists with your own signal |
2560 | you don't register any with libev for the same signal). |
2714 | handlers as long as you don't register any with libev for the same signal. |
2561 | .PP |
2715 | .PP |
2562 | If possible and supported, libev will install its handlers with |
2716 | If possible and supported, libev will install its handlers with |
2563 | \&\f(CW\*(C`SA_RESTART\*(C'\fR (or equivalent) behaviour enabled, so system calls should |
2717 | \&\f(CW\*(C`SA_RESTART\*(C'\fR (or equivalent) behaviour enabled, so system calls should |
2564 | not be unduly interrupted. If you have a problem with system calls getting |
2718 | not be unduly interrupted. If you have a problem with system calls getting |
2565 | interrupted by signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher |
2719 | interrupted by signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher |
… | |
… | |
2586 | The simplest way to ensure that the signal mask is reset in the child is |
2740 | The simplest way to ensure that the signal mask is reset in the child is |
2587 | to install a fork handler with \f(CW\*(C`pthread_atfork\*(C'\fR that resets it. That will |
2741 | to install a fork handler with \f(CW\*(C`pthread_atfork\*(C'\fR that resets it. That will |
2588 | catch fork calls done by libraries (such as the libc) as well. |
2742 | catch fork calls done by libraries (such as the libc) as well. |
2589 | .PP |
2743 | .PP |
2590 | In current versions of libev, the signal will not be blocked indefinitely |
2744 | In current versions of libev, the signal will not be blocked indefinitely |
2591 | unless you use the \f(CW\*(C`signalfd\*(C'\fR \s-1API \s0(\f(CW\*(C`EV_SIGNALFD\*(C'\fR). While this reduces |
2745 | unless you use the \f(CW\*(C`signalfd\*(C'\fR \s-1API\s0 (\f(CW\*(C`EV_SIGNALFD\*(C'\fR). While this reduces |
2592 | the window of opportunity for problems, it will not go away, as libev |
2746 | the window of opportunity for problems, it will not go away, as libev |
2593 | \&\fIhas\fR to modify the signal mask, at least temporarily. |
2747 | \&\fIhas\fR to modify the signal mask, at least temporarily. |
2594 | .PP |
2748 | .PP |
2595 | So I can't stress this enough: \fIIf you do not reset your signal mask when |
2749 | So I can't stress this enough: \fIIf you do not reset your signal mask when |
2596 | you expect it to be empty, you have a race condition in your code\fR. This |
2750 | you expect it to be empty, you have a race condition in your code\fR. This |
… | |
… | |
3048 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
3202 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
3049 | Prepare and check watchers are often (but not always) used in pairs: |
3203 | Prepare and check watchers are often (but not always) used in pairs: |
3050 | prepare watchers get invoked before the process blocks and check watchers |
3204 | prepare watchers get invoked before the process blocks and check watchers |
3051 | afterwards. |
3205 | afterwards. |
3052 | .PP |
3206 | .PP |
3053 | You \fImust not\fR call \f(CW\*(C`ev_run\*(C'\fR or similar functions that enter |
3207 | You \fImust not\fR call \f(CW\*(C`ev_run\*(C'\fR (or similar functions that enter the |
3054 | the current event loop from either \f(CW\*(C`ev_prepare\*(C'\fR or \f(CW\*(C`ev_check\*(C'\fR |
3208 | current event loop) or \f(CW\*(C`ev_loop_fork\*(C'\fR from either \f(CW\*(C`ev_prepare\*(C'\fR or |
3055 | watchers. Other loops than the current one are fine, however. The |
3209 | \&\f(CW\*(C`ev_check\*(C'\fR watchers. Other loops than the current one are fine, |
3056 | rationale behind this is that you do not need to check for recursion in |
3210 | however. The rationale behind this is that you do not need to check |
3057 | those watchers, i.e. the sequence will always be \f(CW\*(C`ev_prepare\*(C'\fR, blocking, |
3211 | for recursion in those watchers, i.e. the sequence will always be |
3058 | \&\f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each kind they will always be |
3212 | \&\f(CW\*(C`ev_prepare\*(C'\fR, blocking, \f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each |
3059 | called in pairs bracketing the blocking call. |
3213 | kind they will always be called in pairs bracketing the blocking call. |
3060 | .PP |
3214 | .PP |
3061 | Their main purpose is to integrate other event mechanisms into libev and |
3215 | Their main purpose is to integrate other event mechanisms into libev and |
3062 | their use is somewhat advanced. They could be used, for example, to track |
3216 | their use is somewhat advanced. They could be used, for example, to track |
3063 | variable changes, implement your own watchers, integrate net-snmp or a |
3217 | variable changes, implement your own watchers, integrate net-snmp or a |
3064 | coroutine library and lots more. They are also occasionally useful if |
3218 | coroutine library and lots more. They are also occasionally useful if |
… | |
… | |
3358 | .PP |
3512 | .PP |
3359 | .Vb 3 |
3513 | .Vb 3 |
3360 | \& struct ev_loop *loop_hi = ev_default_init (0); |
3514 | \& struct ev_loop *loop_hi = ev_default_init (0); |
3361 | \& struct ev_loop *loop_lo = 0; |
3515 | \& struct ev_loop *loop_lo = 0; |
3362 | \& ev_embed embed; |
3516 | \& ev_embed embed; |
3363 | \& |
3517 | \& |
3364 | \& // see if there is a chance of getting one that works |
3518 | \& // see if there is a chance of getting one that works |
3365 | \& // (remember that a flags value of 0 means autodetection) |
3519 | \& // (remember that a flags value of 0 means autodetection) |
3366 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3520 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3367 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3521 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3368 | \& : 0; |
3522 | \& : 0; |
… | |
… | |
3384 | .PP |
3538 | .PP |
3385 | .Vb 3 |
3539 | .Vb 3 |
3386 | \& struct ev_loop *loop = ev_default_init (0); |
3540 | \& struct ev_loop *loop = ev_default_init (0); |
3387 | \& struct ev_loop *loop_socket = 0; |
3541 | \& struct ev_loop *loop_socket = 0; |
3388 | \& ev_embed embed; |
3542 | \& ev_embed embed; |
3389 | \& |
3543 | \& |
3390 | \& if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3544 | \& if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3391 | \& if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3545 | \& if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3392 | \& { |
3546 | \& { |
3393 | \& ev_embed_init (&embed, 0, loop_socket); |
3547 | \& ev_embed_init (&embed, 0, loop_socket); |
3394 | \& ev_embed_start (loop, &embed); |
3548 | \& ev_embed_start (loop, &embed); |
… | |
… | |
3411 | of course. |
3565 | of course. |
3412 | .PP |
3566 | .PP |
3413 | \fIThe special problem of life after fork \- how is it possible?\fR |
3567 | \fIThe special problem of life after fork \- how is it possible?\fR |
3414 | .IX Subsection "The special problem of life after fork - how is it possible?" |
3568 | .IX Subsection "The special problem of life after fork - how is it possible?" |
3415 | .PP |
3569 | .PP |
3416 | Most uses of \f(CW\*(C`fork()\*(C'\fR consist of forking, then some simple calls to set |
3570 | Most uses of \f(CW\*(C`fork ()\*(C'\fR consist of forking, then some simple calls to set |
3417 | up/change the process environment, followed by a call to \f(CW\*(C`exec()\*(C'\fR. This |
3571 | up/change the process environment, followed by a call to \f(CW\*(C`exec()\*(C'\fR. This |
3418 | sequence should be handled by libev without any problems. |
3572 | sequence should be handled by libev without any problems. |
3419 | .PP |
3573 | .PP |
3420 | This changes when the application actually wants to do event handling |
3574 | This changes when the application actually wants to do event handling |
3421 | in the child, or both parent in child, in effect \*(L"continuing\*(R" after the |
3575 | in the child, or both parent in child, in effect \*(L"continuing\*(R" after the |
… | |
… | |
3638 | is a time window between the event loop checking and resetting the async |
3792 | is a time window between the event loop checking and resetting the async |
3639 | notification, and the callback being invoked. |
3793 | notification, and the callback being invoked. |
3640 | .SH "OTHER FUNCTIONS" |
3794 | .SH "OTHER FUNCTIONS" |
3641 | .IX Header "OTHER FUNCTIONS" |
3795 | .IX Header "OTHER FUNCTIONS" |
3642 | There are some other functions of possible interest. Described. Here. Now. |
3796 | There are some other functions of possible interest. Described. Here. Now. |
3643 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 |
3797 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback, arg)" 4 |
3644 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" |
3798 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback, arg)" |
3645 | This function combines a simple timer and an I/O watcher, calls your |
3799 | This function combines a simple timer and an I/O watcher, calls your |
3646 | callback on whichever event happens first and automatically stops both |
3800 | callback on whichever event happens first and automatically stops both |
3647 | watchers. This is useful if you want to wait for a single event on an fd |
3801 | watchers. This is useful if you want to wait for a single event on an fd |
3648 | or timeout without having to allocate/configure/start/stop/free one or |
3802 | or timeout without having to allocate/configure/start/stop/free one or |
3649 | more watchers yourself. |
3803 | more watchers yourself. |
… | |
… | |
3864 | .PP |
4018 | .PP |
3865 | First, you need to associate some data with the event loop: |
4019 | First, you need to associate some data with the event loop: |
3866 | .PP |
4020 | .PP |
3867 | .Vb 6 |
4021 | .Vb 6 |
3868 | \& typedef struct { |
4022 | \& typedef struct { |
3869 | \& mutex_t lock; /* global loop lock */ |
4023 | \& pthread_mutex_t lock; /* global loop lock */ |
|
|
4024 | \& pthread_t tid; |
|
|
4025 | \& pthread_cond_t invoke_cv; |
3870 | \& ev_async async_w; |
4026 | \& ev_async async_w; |
3871 | \& thread_t tid; |
|
|
3872 | \& cond_t invoke_cv; |
|
|
3873 | \& } userdata; |
4027 | \& } userdata; |
3874 | \& |
4028 | \& |
3875 | \& void prepare_loop (EV_P) |
4029 | \& void prepare_loop (EV_P) |
3876 | \& { |
4030 | \& { |
3877 | \& // for simplicity, we use a static userdata struct. |
4031 | \& // for simplicity, we use a static userdata struct. |
3878 | \& static userdata u; |
4032 | \& static userdata u; |
3879 | \& |
4033 | \& |
3880 | \& ev_async_init (&u\->async_w, async_cb); |
4034 | \& ev_async_init (&u.async_w, async_cb); |
3881 | \& ev_async_start (EV_A_ &u\->async_w); |
4035 | \& ev_async_start (EV_A_ &u.async_w); |
3882 | \& |
4036 | \& |
3883 | \& pthread_mutex_init (&u\->lock, 0); |
4037 | \& pthread_mutex_init (&u.lock, 0); |
3884 | \& pthread_cond_init (&u\->invoke_cv, 0); |
4038 | \& pthread_cond_init (&u.invoke_cv, 0); |
3885 | \& |
4039 | \& |
3886 | \& // now associate this with the loop |
4040 | \& // now associate this with the loop |
3887 | \& ev_set_userdata (EV_A_ u); |
4041 | \& ev_set_userdata (EV_A_ &u); |
3888 | \& ev_set_invoke_pending_cb (EV_A_ l_invoke); |
4042 | \& ev_set_invoke_pending_cb (EV_A_ l_invoke); |
3889 | \& ev_set_loop_release_cb (EV_A_ l_release, l_acquire); |
4043 | \& ev_set_loop_release_cb (EV_A_ l_release, l_acquire); |
3890 | \& |
4044 | \& |
3891 | \& // then create the thread running ev_run |
4045 | \& // then create the thread running ev_run |
3892 | \& pthread_create (&u\->tid, 0, l_run, EV_A); |
4046 | \& pthread_create (&u.tid, 0, l_run, EV_A); |
3893 | \& } |
4047 | \& } |
3894 | .Ve |
4048 | .Ve |
3895 | .PP |
4049 | .PP |
3896 | The callback for the \f(CW\*(C`ev_async\*(C'\fR watcher does nothing: the watcher is used |
4050 | The callback for the \f(CW\*(C`ev_async\*(C'\fR watcher does nothing: the watcher is used |
3897 | solely to wake up the event loop so it takes notice of any new watchers |
4051 | solely to wake up the event loop so it takes notice of any new watchers |
… | |
… | |
4049 | files, \fImy_ev.h\fR and \fImy_ev.c\fR that include the respective libev files: |
4203 | files, \fImy_ev.h\fR and \fImy_ev.c\fR that include the respective libev files: |
4050 | .PP |
4204 | .PP |
4051 | .Vb 4 |
4205 | .Vb 4 |
4052 | \& // my_ev.h |
4206 | \& // my_ev.h |
4053 | \& #define EV_CB_DECLARE(type) struct my_coro *cb; |
4207 | \& #define EV_CB_DECLARE(type) struct my_coro *cb; |
4054 | \& #define EV_CB_INVOKE(watcher) switch_to ((watcher)\->cb); |
4208 | \& #define EV_CB_INVOKE(watcher) switch_to ((watcher)\->cb) |
4055 | \& #include "../libev/ev.h" |
4209 | \& #include "../libev/ev.h" |
4056 | \& |
4210 | \& |
4057 | \& // my_ev.c |
4211 | \& // my_ev.c |
4058 | \& #define EV_H "my_ev.h" |
4212 | \& #define EV_H "my_ev.h" |
4059 | \& #include "../libev/ev.c" |
4213 | \& #include "../libev/ev.c" |
… | |
… | |
4099 | The normal C \s-1API\s0 should work fine when used from \*(C+: both ev.h and the |
4253 | The normal C \s-1API\s0 should work fine when used from \*(C+: both ev.h and the |
4100 | libev sources can be compiled as \*(C+. Therefore, code that uses the C \s-1API\s0 |
4254 | libev sources can be compiled as \*(C+. Therefore, code that uses the C \s-1API\s0 |
4101 | will work fine. |
4255 | will work fine. |
4102 | .PP |
4256 | .PP |
4103 | Proper exception specifications might have to be added to callbacks passed |
4257 | Proper exception specifications might have to be added to callbacks passed |
4104 | to libev: exceptions may be thrown only from watcher callbacks, all |
4258 | to libev: exceptions may be thrown only from watcher callbacks, all other |
4105 | other callbacks (allocator, syserr, loop acquire/release and periodic |
4259 | callbacks (allocator, syserr, loop acquire/release and periodic reschedule |
4106 | reschedule callbacks) must not throw exceptions, and might need a \f(CW\*(C`throw |
4260 | callbacks) must not throw exceptions, and might need a \f(CW\*(C`noexcept\*(C'\fR |
4107 | ()\*(C'\fR specification. If you have code that needs to be compiled as both C |
4261 | specification. If you have code that needs to be compiled as both C and |
4108 | and \*(C+ you can use the \f(CW\*(C`EV_THROW\*(C'\fR macro for this: |
4262 | \&\*(C+ you can use the \f(CW\*(C`EV_NOEXCEPT\*(C'\fR macro for this: |
4109 | .PP |
4263 | .PP |
4110 | .Vb 6 |
4264 | .Vb 6 |
4111 | \& static void |
4265 | \& static void |
4112 | \& fatal_error (const char *msg) EV_THROW |
4266 | \& fatal_error (const char *msg) EV_NOEXCEPT |
4113 | \& { |
4267 | \& { |
4114 | \& perror (msg); |
4268 | \& perror (msg); |
4115 | \& abort (); |
4269 | \& abort (); |
4116 | \& } |
4270 | \& } |
4117 | \& |
4271 | \& |
… | |
… | |
4245 | \& void operator() (ev::io &w, int revents) |
4399 | \& void operator() (ev::io &w, int revents) |
4246 | \& { |
4400 | \& { |
4247 | \& ... |
4401 | \& ... |
4248 | \& } |
4402 | \& } |
4249 | \& } |
4403 | \& } |
4250 | \& |
4404 | \& |
4251 | \& myfunctor f; |
4405 | \& myfunctor f; |
4252 | \& |
4406 | \& |
4253 | \& ev::io w; |
4407 | \& ev::io w; |
4254 | \& w.set (&f); |
4408 | \& w.set (&f); |
4255 | .Ve |
4409 | .Ve |
… | |
… | |
4281 | gets automatically stopped and restarted when reconfiguring it with this |
4435 | gets automatically stopped and restarted when reconfiguring it with this |
4282 | method. |
4436 | method. |
4283 | .Sp |
4437 | .Sp |
4284 | For \f(CW\*(C`ev::embed\*(C'\fR watchers this method is called \f(CW\*(C`set_embed\*(C'\fR, to avoid |
4438 | For \f(CW\*(C`ev::embed\*(C'\fR watchers this method is called \f(CW\*(C`set_embed\*(C'\fR, to avoid |
4285 | clashing with the \f(CW\*(C`set (loop)\*(C'\fR method. |
4439 | clashing with the \f(CW\*(C`set (loop)\*(C'\fR method. |
|
|
4440 | .Sp |
|
|
4441 | For \f(CW\*(C`ev::io\*(C'\fR watchers there is an additional \f(CW\*(C`set\*(C'\fR method that acepts a |
|
|
4442 | new event mask only, and internally calls \f(CW\*(C`ev_io_modify\*(C'\fR. |
4286 | .IP "w\->start ()" 4 |
4443 | .IP "w\->start ()" 4 |
4287 | .IX Item "w->start ()" |
4444 | .IX Item "w->start ()" |
4288 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the |
4445 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the |
4289 | constructor already stores the event loop. |
4446 | constructor already stores the event loop. |
4290 | .IP "w\->start ([arguments])" 4 |
4447 | .IP "w\->start ([arguments])" 4 |
… | |
… | |
4491 | \& #include "ev.c" |
4648 | \& #include "ev.c" |
4492 | .Ve |
4649 | .Ve |
4493 | .PP |
4650 | .PP |
4494 | This will automatically include \fIev.h\fR, too, and should be done in a |
4651 | This will automatically include \fIev.h\fR, too, and should be done in a |
4495 | single C source file only to provide the function implementations. To use |
4652 | single C source file only to provide the function implementations. To use |
4496 | it, do the same for \fIev.h\fR in all files wishing to use this \s-1API \s0(best |
4653 | it, do the same for \fIev.h\fR in all files wishing to use this \s-1API\s0 (best |
4497 | done by writing a wrapper around \fIev.h\fR that you can include instead and |
4654 | done by writing a wrapper around \fIev.h\fR that you can include instead and |
4498 | where you can put other configuration options): |
4655 | where you can put other configuration options): |
4499 | .PP |
4656 | .PP |
4500 | .Vb 2 |
4657 | .Vb 2 |
4501 | \& #define EV_STANDALONE 1 |
4658 | \& #define EV_STANDALONE 1 |
… | |
… | |
4515 | \& ev_vars.h |
4672 | \& ev_vars.h |
4516 | \& ev_wrap.h |
4673 | \& ev_wrap.h |
4517 | \& |
4674 | \& |
4518 | \& ev_win32.c required on win32 platforms only |
4675 | \& ev_win32.c required on win32 platforms only |
4519 | \& |
4676 | \& |
4520 | \& ev_select.c only when select backend is enabled (which is enabled by default) |
4677 | \& ev_select.c only when select backend is enabled |
4521 | \& ev_poll.c only when poll backend is enabled (disabled by default) |
4678 | \& ev_poll.c only when poll backend is enabled |
4522 | \& ev_epoll.c only when the epoll backend is enabled (disabled by default) |
4679 | \& ev_epoll.c only when the epoll backend is enabled |
|
|
4680 | \& ev_linuxaio.c only when the linux aio backend is enabled |
|
|
4681 | \& ev_iouring.c only when the linux io_uring backend is enabled |
4523 | \& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
4682 | \& ev_kqueue.c only when the kqueue backend is enabled |
4524 | \& ev_port.c only when the solaris port backend is enabled (disabled by default) |
4683 | \& ev_port.c only when the solaris port backend is enabled |
4525 | .Ve |
4684 | .Ve |
4526 | .PP |
4685 | .PP |
4527 | \&\fIev.c\fR includes the backend files directly when enabled, so you only need |
4686 | \&\fIev.c\fR includes the backend files directly when enabled, so you only need |
4528 | to compile this single file. |
4687 | to compile this single file. |
4529 | .PP |
4688 | .PP |
… | |
… | |
4574 | values when compiling libev vs. including \fIev.h\fR, so it is permissible |
4733 | values when compiling libev vs. including \fIev.h\fR, so it is permissible |
4575 | to redefine them before including \fIev.h\fR without breaking compatibility |
4734 | to redefine them before including \fIev.h\fR without breaking compatibility |
4576 | to a compiled library. All other symbols change the \s-1ABI,\s0 which means all |
4735 | to a compiled library. All other symbols change the \s-1ABI,\s0 which means all |
4577 | users of libev and the libev code itself must be compiled with compatible |
4736 | users of libev and the libev code itself must be compiled with compatible |
4578 | settings. |
4737 | settings. |
4579 | .IP "\s-1EV_COMPAT3 \s0(h)" 4 |
4738 | .IP "\s-1EV_COMPAT3\s0 (h)" 4 |
4580 | .IX Item "EV_COMPAT3 (h)" |
4739 | .IX Item "EV_COMPAT3 (h)" |
4581 | Backwards compatibility is a major concern for libev. This is why this |
4740 | Backwards compatibility is a major concern for libev. This is why this |
4582 | release of libev comes with wrappers for the functions and symbols that |
4741 | release of libev comes with wrappers for the functions and symbols that |
4583 | have been renamed between libev version 3 and 4. |
4742 | have been renamed between libev version 3 and 4. |
4584 | .Sp |
4743 | .Sp |
… | |
… | |
4589 | typedef in that case. |
4748 | typedef in that case. |
4590 | .Sp |
4749 | .Sp |
4591 | In some future version, the default for \f(CW\*(C`EV_COMPAT3\*(C'\fR will become \f(CW0\fR, |
4750 | In some future version, the default for \f(CW\*(C`EV_COMPAT3\*(C'\fR will become \f(CW0\fR, |
4592 | and in some even more future version the compatibility code will be |
4751 | and in some even more future version the compatibility code will be |
4593 | removed completely. |
4752 | removed completely. |
4594 | .IP "\s-1EV_STANDALONE \s0(h)" 4 |
4753 | .IP "\s-1EV_STANDALONE\s0 (h)" 4 |
4595 | .IX Item "EV_STANDALONE (h)" |
4754 | .IX Item "EV_STANDALONE (h)" |
4596 | Must always be \f(CW1\fR if you do not use autoconf configuration, which |
4755 | Must always be \f(CW1\fR if you do not use autoconf configuration, which |
4597 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
4756 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
4598 | implementations for some libevent functions (such as logging, which is not |
4757 | implementations for some libevent functions (such as logging, which is not |
4599 | supported). It will also not define any of the structs usually found in |
4758 | supported). It will also not define any of the structs usually found in |
… | |
… | |
4640 | higher, as it simplifies linking (no need for \f(CW\*(C`\-lrt\*(C'\fR). |
4799 | higher, as it simplifies linking (no need for \f(CW\*(C`\-lrt\*(C'\fR). |
4641 | .IP "\s-1EV_USE_NANOSLEEP\s0" 4 |
4800 | .IP "\s-1EV_USE_NANOSLEEP\s0" 4 |
4642 | .IX Item "EV_USE_NANOSLEEP" |
4801 | .IX Item "EV_USE_NANOSLEEP" |
4643 | If defined to be \f(CW1\fR, libev will assume that \f(CW\*(C`nanosleep ()\*(C'\fR is available |
4802 | If defined to be \f(CW1\fR, libev will assume that \f(CW\*(C`nanosleep ()\*(C'\fR is available |
4644 | and will use it for delays. Otherwise it will use \f(CW\*(C`select ()\*(C'\fR. |
4803 | and will use it for delays. Otherwise it will use \f(CW\*(C`select ()\*(C'\fR. |
|
|
4804 | .IP "\s-1EV_USE_EVENTFD\s0" 4 |
|
|
4805 | .IX Item "EV_USE_EVENTFD" |
|
|
4806 | If defined to be \f(CW1\fR, then libev will assume that \f(CW\*(C`eventfd ()\*(C'\fR is |
|
|
4807 | available and will probe for kernel support at runtime. This will improve |
|
|
4808 | \&\f(CW\*(C`ev_signal\*(C'\fR and \f(CW\*(C`ev_async\*(C'\fR performance and reduce resource consumption. |
|
|
4809 | If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc |
|
|
4810 | 2.7 or newer, otherwise disabled. |
|
|
4811 | .IP "\s-1EV_USE_SIGNALFD\s0" 4 |
|
|
4812 | .IX Item "EV_USE_SIGNALFD" |
|
|
4813 | If defined to be \f(CW1\fR, then libev will assume that \f(CW\*(C`signalfd ()\*(C'\fR is |
|
|
4814 | available and will probe for kernel support at runtime. This enables |
|
|
4815 | the use of \s-1EVFLAG_SIGNALFD\s0 for faster and simpler signal handling. If |
|
|
4816 | undefined, it will be enabled if the headers indicate GNU/Linux + Glibc |
|
|
4817 | 2.7 or newer, otherwise disabled. |
|
|
4818 | .IP "\s-1EV_USE_TIMERFD\s0" 4 |
|
|
4819 | .IX Item "EV_USE_TIMERFD" |
|
|
4820 | If defined to be \f(CW1\fR, then libev will assume that \f(CW\*(C`timerfd ()\*(C'\fR is |
|
|
4821 | available and will probe for kernel support at runtime. This allows |
|
|
4822 | libev to detect time jumps accurately. If undefined, it will be enabled |
|
|
4823 | if the headers indicate GNU/Linux + Glibc 2.8 or newer and define |
|
|
4824 | \&\f(CW\*(C`TFD_TIMER_CANCEL_ON_SET\*(C'\fR, otherwise disabled. |
4645 | .IP "\s-1EV_USE_EVENTFD\s0" 4 |
4825 | .IP "\s-1EV_USE_EVENTFD\s0" 4 |
4646 | .IX Item "EV_USE_EVENTFD" |
4826 | .IX Item "EV_USE_EVENTFD" |
4647 | If defined to be \f(CW1\fR, then libev will assume that \f(CW\*(C`eventfd ()\*(C'\fR is |
4827 | If defined to be \f(CW1\fR, then libev will assume that \f(CW\*(C`eventfd ()\*(C'\fR is |
4648 | available and will probe for kernel support at runtime. This will improve |
4828 | available and will probe for kernel support at runtime. This will improve |
4649 | \&\f(CW\*(C`ev_signal\*(C'\fR and \f(CW\*(C`ev_async\*(C'\fR performance and reduce resource consumption. |
4829 | \&\f(CW\*(C`ev_signal\*(C'\fR and \f(CW\*(C`ev_async\*(C'\fR performance and reduce resource consumption. |
… | |
… | |
4708 | If defined to be \f(CW1\fR, libev will compile in support for the Linux |
4888 | If defined to be \f(CW1\fR, libev will compile in support for the Linux |
4709 | \&\f(CW\*(C`epoll\*(C'\fR(7) backend. Its availability will be detected at runtime, |
4889 | \&\f(CW\*(C`epoll\*(C'\fR(7) backend. Its availability will be detected at runtime, |
4710 | otherwise another method will be used as fallback. This is the preferred |
4890 | otherwise another method will be used as fallback. This is the preferred |
4711 | backend for GNU/Linux systems. If undefined, it will be enabled if the |
4891 | backend for GNU/Linux systems. If undefined, it will be enabled if the |
4712 | headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
4892 | headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
|
|
4893 | .IP "\s-1EV_USE_LINUXAIO\s0" 4 |
|
|
4894 | .IX Item "EV_USE_LINUXAIO" |
|
|
4895 | If defined to be \f(CW1\fR, libev will compile in support for the Linux aio |
|
|
4896 | backend (\f(CW\*(C`EV_USE_EPOLL\*(C'\fR must also be enabled). If undefined, it will be |
|
|
4897 | enabled on linux, otherwise disabled. |
|
|
4898 | .IP "\s-1EV_USE_IOURING\s0" 4 |
|
|
4899 | .IX Item "EV_USE_IOURING" |
|
|
4900 | If defined to be \f(CW1\fR, libev will compile in support for the Linux |
|
|
4901 | io_uring backend (\f(CW\*(C`EV_USE_EPOLL\*(C'\fR must also be enabled). Due to it's |
|
|
4902 | current limitations it has to be requested explicitly. If undefined, it |
|
|
4903 | will be enabled on linux, otherwise disabled. |
4713 | .IP "\s-1EV_USE_KQUEUE\s0" 4 |
4904 | .IP "\s-1EV_USE_KQUEUE\s0" 4 |
4714 | .IX Item "EV_USE_KQUEUE" |
4905 | .IX Item "EV_USE_KQUEUE" |
4715 | If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style |
4906 | If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style |
4716 | \&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime, |
4907 | \&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime, |
4717 | otherwise another method will be used as fallback. This is the preferred |
4908 | otherwise another method will be used as fallback. This is the preferred |
… | |
… | |
4757 | handler \*(L"locking\*(R" as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR |
4948 | handler \*(L"locking\*(R" as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR |
4758 | watchers. |
4949 | watchers. |
4759 | .Sp |
4950 | .Sp |
4760 | In the absence of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR |
4951 | In the absence of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR |
4761 | (from \fIsignal.h\fR), which is usually good enough on most platforms. |
4952 | (from \fIsignal.h\fR), which is usually good enough on most platforms. |
4762 | .IP "\s-1EV_H \s0(h)" 4 |
4953 | .IP "\s-1EV_H\s0 (h)" 4 |
4763 | .IX Item "EV_H (h)" |
4954 | .IX Item "EV_H (h)" |
4764 | The name of the \fIev.h\fR header file used to include it. The default if |
4955 | The name of the \fIev.h\fR header file used to include it. The default if |
4765 | undefined is \f(CW"ev.h"\fR in \fIevent.h\fR, \fIev.c\fR and \fIev++.h\fR. This can be |
4956 | undefined is \f(CW"ev.h"\fR in \fIevent.h\fR, \fIev.c\fR and \fIev++.h\fR. This can be |
4766 | used to virtually rename the \fIev.h\fR header file in case of conflicts. |
4957 | used to virtually rename the \fIev.h\fR header file in case of conflicts. |
4767 | .IP "\s-1EV_CONFIG_H \s0(h)" 4 |
4958 | .IP "\s-1EV_CONFIG_H\s0 (h)" 4 |
4768 | .IX Item "EV_CONFIG_H (h)" |
4959 | .IX Item "EV_CONFIG_H (h)" |
4769 | If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override |
4960 | If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override |
4770 | \&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to |
4961 | \&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to |
4771 | \&\f(CW\*(C`EV_H\*(C'\fR, above. |
4962 | \&\f(CW\*(C`EV_H\*(C'\fR, above. |
4772 | .IP "\s-1EV_EVENT_H \s0(h)" 4 |
4963 | .IP "\s-1EV_EVENT_H\s0 (h)" 4 |
4773 | .IX Item "EV_EVENT_H (h)" |
4964 | .IX Item "EV_EVENT_H (h)" |
4774 | Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea |
4965 | Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea |
4775 | of how the \fIevent.h\fR header can be found, the default is \f(CW"event.h"\fR. |
4966 | of how the \fIevent.h\fR header can be found, the default is \f(CW"event.h"\fR. |
4776 | .IP "\s-1EV_PROTOTYPES \s0(h)" 4 |
4967 | .IP "\s-1EV_PROTOTYPES\s0 (h)" 4 |
4777 | .IX Item "EV_PROTOTYPES (h)" |
4968 | .IX Item "EV_PROTOTYPES (h)" |
4778 | If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function |
4969 | If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function |
4779 | prototypes, but still define all the structs and other symbols. This is |
4970 | prototypes, but still define all the structs and other symbols. This is |
4780 | occasionally useful if you want to provide your own wrapper functions |
4971 | occasionally useful if you want to provide your own wrapper functions |
4781 | around libev functions. |
4972 | around libev functions. |
… | |
… | |
4974 | called. If set to \f(CW2\fR, then the internal verification code will be |
5165 | called. If set to \f(CW2\fR, then the internal verification code will be |
4975 | called once per loop, which can slow down libev. If set to \f(CW3\fR, then the |
5166 | called once per loop, which can slow down libev. If set to \f(CW3\fR, then the |
4976 | verification code will be called very frequently, which will slow down |
5167 | verification code will be called very frequently, which will slow down |
4977 | libev considerably. |
5168 | libev considerably. |
4978 | .Sp |
5169 | .Sp |
|
|
5170 | Verification errors are reported via C's \f(CW\*(C`assert\*(C'\fR mechanism, so if you |
|
|
5171 | disable that (e.g. by defining \f(CW\*(C`NDEBUG\*(C'\fR) then no errors will be reported. |
|
|
5172 | .Sp |
4979 | The default is \f(CW1\fR, unless \f(CW\*(C`EV_FEATURES\*(C'\fR overrides it, in which case it |
5173 | The default is \f(CW1\fR, unless \f(CW\*(C`EV_FEATURES\*(C'\fR overrides it, in which case it |
4980 | will be \f(CW0\fR. |
5174 | will be \f(CW0\fR. |
4981 | .IP "\s-1EV_COMMON\s0" 4 |
5175 | .IP "\s-1EV_COMMON\s0" 4 |
4982 | .IX Item "EV_COMMON" |
5176 | .IX Item "EV_COMMON" |
4983 | By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining |
5177 | By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining |
… | |
… | |
4990 | .Vb 3 |
5184 | .Vb 3 |
4991 | \& #define EV_COMMON \e |
5185 | \& #define EV_COMMON \e |
4992 | \& SV *self; /* contains this struct */ \e |
5186 | \& SV *self; /* contains this struct */ \e |
4993 | \& SV *cb_sv, *fh /* note no trailing ";" */ |
5187 | \& SV *cb_sv, *fh /* note no trailing ";" */ |
4994 | .Ve |
5188 | .Ve |
4995 | .IP "\s-1EV_CB_DECLARE \s0(type)" 4 |
5189 | .IP "\s-1EV_CB_DECLARE\s0 (type)" 4 |
4996 | .IX Item "EV_CB_DECLARE (type)" |
5190 | .IX Item "EV_CB_DECLARE (type)" |
4997 | .PD 0 |
5191 | .PD 0 |
4998 | .IP "\s-1EV_CB_INVOKE \s0(watcher, revents)" 4 |
5192 | .IP "\s-1EV_CB_INVOKE\s0 (watcher, revents)" 4 |
4999 | .IX Item "EV_CB_INVOKE (watcher, revents)" |
5193 | .IX Item "EV_CB_INVOKE (watcher, revents)" |
5000 | .IP "ev_set_cb (ev, cb)" 4 |
5194 | .IP "ev_set_cb (ev, cb)" 4 |
5001 | .IX Item "ev_set_cb (ev, cb)" |
5195 | .IX Item "ev_set_cb (ev, cb)" |
5002 | .PD |
5196 | .PD |
5003 | Can be used to change the callback member declaration in each watcher, |
5197 | Can be used to change the callback member declaration in each watcher, |
… | |
… | |
5006 | their default definitions. One possible use for overriding these is to |
5200 | their default definitions. One possible use for overriding these is to |
5007 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
5201 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
5008 | method calls instead of plain function calls in \*(C+. |
5202 | method calls instead of plain function calls in \*(C+. |
5009 | .SS "\s-1EXPORTED API SYMBOLS\s0" |
5203 | .SS "\s-1EXPORTED API SYMBOLS\s0" |
5010 | .IX Subsection "EXPORTED API SYMBOLS" |
5204 | .IX Subsection "EXPORTED API SYMBOLS" |
5011 | If you need to re-export the \s-1API \s0(e.g. via a \s-1DLL\s0) and you need a list of |
5205 | If you need to re-export the \s-1API\s0 (e.g. via a \s-1DLL\s0) and you need a list of |
5012 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
5206 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
5013 | all public symbols, one per line: |
5207 | all public symbols, one per line: |
5014 | .PP |
5208 | .PP |
5015 | .Vb 2 |
5209 | .Vb 2 |
5016 | \& Symbols.ev for libev proper |
5210 | \& Symbols.ev for libev proper |
… | |
… | |
5248 | .PP |
5442 | .PP |
5249 | \fI\f(CI\*(C`select\*(C'\fI is buggy\fR |
5443 | \fI\f(CI\*(C`select\*(C'\fI is buggy\fR |
5250 | .IX Subsection "select is buggy" |
5444 | .IX Subsection "select is buggy" |
5251 | .PP |
5445 | .PP |
5252 | All that's left is \f(CW\*(C`select\*(C'\fR, and of course Apple found a way to fuck this |
5446 | All that's left is \f(CW\*(C`select\*(C'\fR, and of course Apple found a way to fuck this |
5253 | one up as well: On \s-1OS/X, \s0\f(CW\*(C`select\*(C'\fR actively limits the number of file |
5447 | one up as well: On \s-1OS/X,\s0 \f(CW\*(C`select\*(C'\fR actively limits the number of file |
5254 | descriptors you can pass in to 1024 \- your program suddenly crashes when |
5448 | descriptors you can pass in to 1024 \- your program suddenly crashes when |
5255 | you use more. |
5449 | you use more. |
5256 | .PP |
5450 | .PP |
5257 | There is an undocumented \*(L"workaround\*(R" for this \- defining |
5451 | There is an undocumented \*(L"workaround\*(R" for this \- defining |
5258 | \&\f(CW\*(C`_DARWIN_UNLIMITED_SELECT\*(C'\fR, which libev tries to use, so select \fIshould\fR |
5452 | \&\f(CW\*(C`_DARWIN_UNLIMITED_SELECT\*(C'\fR, which libev tries to use, so select \fIshould\fR |
… | |
… | |
5406 | Libev assumes not only that all watcher pointers have the same internal |
5600 | Libev assumes not only that all watcher pointers have the same internal |
5407 | structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO C\s0 for example), but it also |
5601 | structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO C\s0 for example), but it also |
5408 | assumes that the same (machine) code can be used to call any watcher |
5602 | assumes that the same (machine) code can be used to call any watcher |
5409 | callback: The watcher callbacks have different type signatures, but libev |
5603 | callback: The watcher callbacks have different type signatures, but libev |
5410 | calls them using an \f(CW\*(C`ev_watcher *\*(C'\fR internally. |
5604 | calls them using an \f(CW\*(C`ev_watcher *\*(C'\fR internally. |
|
|
5605 | .IP "null pointers and integer zero are represented by 0 bytes" 4 |
|
|
5606 | .IX Item "null pointers and integer zero are represented by 0 bytes" |
|
|
5607 | Libev uses \f(CW\*(C`memset\*(C'\fR to initialise structs and arrays to \f(CW0\fR bytes, and |
|
|
5608 | relies on this setting pointers and integers to null. |
5411 | .IP "pointer accesses must be thread-atomic" 4 |
5609 | .IP "pointer accesses must be thread-atomic" 4 |
5412 | .IX Item "pointer accesses must be thread-atomic" |
5610 | .IX Item "pointer accesses must be thread-atomic" |
5413 | Accessing a pointer value must be atomic, it must both be readable and |
5611 | Accessing a pointer value must be atomic, it must both be readable and |
5414 | writable in one piece \- this is the case on all current architectures. |
5612 | writable in one piece \- this is the case on all current architectures. |
5415 | .ie n .IP """sig_atomic_t volatile"" must be thread-atomic as well" 4 |
5613 | .ie n .IP """sig_atomic_t volatile"" must be thread-atomic as well" 4 |