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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 "2019-06-23" "libev-4.25" "libev - high performance full featured event loop" |
137 | .\" For nroff, turn off justification. Always turn off hyphenation; it makes |
137 | .\" For nroff, turn off justification. Always turn off hyphenation; it makes |
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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392 | .Sp |
392 | .Sp |
393 | You could override this function in high-availability programs to, say, |
393 | 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, |
394 | 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. |
395 | or even to sleep a while and retry until some memory is available. |
396 | .Sp |
396 | .Sp |
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397 | Example: The following is the \f(CW\*(C`realloc\*(C'\fR function that libev itself uses |
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398 | 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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399 | is probably a good basis for your own implementation. |
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400 | .Sp |
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401 | .Vb 5 |
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402 | \& static void * |
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403 | \& ev_realloc_emul (void *ptr, long size) EV_NOEXCEPT |
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404 | \& { |
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405 | \& if (size) |
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406 | \& return realloc (ptr, size); |
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407 | \& |
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408 | \& free (ptr); |
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409 | \& return 0; |
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410 | \& } |
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411 | .Ve |
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412 | .Sp |
397 | Example: Replace the libev allocator with one that waits a bit and then |
413 | 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). |
414 | retries. |
399 | .Sp |
415 | .Sp |
400 | .Vb 6 |
416 | .Vb 8 |
401 | \& static void * |
417 | \& static void * |
402 | \& persistent_realloc (void *ptr, size_t size) |
418 | \& persistent_realloc (void *ptr, size_t size) |
403 | \& { |
419 | \& { |
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420 | \& if (!size) |
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421 | \& { |
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422 | \& free (ptr); |
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423 | \& return 0; |
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424 | \& } |
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425 | \& |
404 | \& for (;;) |
426 | \& for (;;) |
405 | \& { |
427 | \& { |
406 | \& void *newptr = realloc (ptr, size); |
428 | \& void *newptr = realloc (ptr, size); |
407 | \& |
429 | \& |
408 | \& if (newptr) |
430 | \& if (newptr) |
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536 | make libev check for a fork in each iteration by enabling this flag. |
558 | make libev check for a fork in each iteration by enabling this flag. |
537 | .Sp |
559 | .Sp |
538 | This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop, |
560 | 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 |
561 | 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 |
562 | 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 |
563 | 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 |
564 | 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). |
565 | system also has \f(CW\*(C`pthread_atfork\*(C'\fR which is even faster). (Update: glibc |
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566 | versions 2.25 apparently removed the \f(CW\*(C`getpid\*(C'\fR optimisation again). |
544 | .Sp |
567 | .Sp |
545 | The big advantage of this flag is that you can forget about fork (and |
568 | 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 |
569 | forget about forgetting to tell libev about forking, although you still |
547 | flag. |
570 | have to ignore \f(CW\*(C`SIGPIPE\*(C'\fR) when you use this flag. |
548 | .Sp |
571 | .Sp |
549 | This flag setting cannot be overridden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR |
572 | This flag setting cannot be overridden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR |
550 | environment variable. |
573 | environment variable. |
551 | .ie n .IP """EVFLAG_NOINOTIFY""" 4 |
574 | .ie n .IP """EVFLAG_NOINOTIFY""" 4 |
552 | .el .IP "\f(CWEVFLAG_NOINOTIFY\fR" 4 |
575 | .el .IP "\f(CWEVFLAG_NOINOTIFY\fR" 4 |
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584 | .Sp |
607 | .Sp |
585 | This flag's behaviour will become the default in future versions of libev. |
608 | This flag's behaviour will become the default in future versions of libev. |
586 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
609 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
587 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
610 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
588 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
611 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
589 | This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
612 | 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, |
613 | 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 |
614 | 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 |
615 | 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. |
616 | usually the fastest backend for a low number of (low-numbered :) fds. |
594 | .Sp |
617 | .Sp |
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603 | \&\f(CW\*(C`writefds\*(C'\fR set (and to work around Microsoft Windows bugs, also onto the |
626 | \&\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). |
627 | \&\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 |
628 | .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 |
629 | .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)" |
630 | .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 |
631 | 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 |
632 | 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 |
633 | 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, |
634 | 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 |
635 | i.e. O(total_fds). See the entry for \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR, above, for |
613 | performance tips. |
636 | performance tips. |
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615 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR to \f(CW\*(C`POLLIN | POLLERR | POLLHUP\*(C'\fR, and |
638 | 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. |
639 | \&\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 |
640 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
618 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
641 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
619 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
642 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
620 | Use the linux-specific \fIepoll\fR\|(7) interface (for both pre\- and post\-2.6.9 |
643 | Use the linux-specific \fBepoll\fR\|(7) interface (for both pre\- and post\-2.6.9 |
621 | kernels). |
644 | kernels). |
622 | .Sp |
645 | .Sp |
623 | For few fds, this backend is a bit little slower than poll and select, but |
646 | 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 |
647 | 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 |
648 | O(total_fds) where total_fds is the total number of fds (or the highest |
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671 | All this means that, in practice, \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR can be as fast or |
694 | 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 |
695 | faster than epoll for maybe up to a hundred file descriptors, depending on |
673 | the usage. So sad. |
696 | the usage. So sad. |
674 | .Sp |
697 | .Sp |
675 | While nominally embeddable in other event loops, this feature is broken in |
698 | While nominally embeddable in other event loops, this feature is broken in |
676 | all kernel versions tested so far. |
699 | a lot of kernel revisions, but probably(!) works in current versions. |
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700 | .Sp |
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701 | 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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702 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
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703 | .ie n .IP """EVBACKEND_LINUXAIO"" (value 64, Linux)" 4 |
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704 | .el .IP "\f(CWEVBACKEND_LINUXAIO\fR (value 64, Linux)" 4 |
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705 | .IX Item "EVBACKEND_LINUXAIO (value 64, Linux)" |
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706 | Use the linux-specific linux aio (\fInot\fR \f(CWaio(7)\fR but \f(CWio_submit(2)\fR) event interface available in post\-4.18 kernels. |
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707 | .Sp |
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708 | If this backend works for you (as of this writing, it was very |
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709 | experimental), it is the best event interface available on linux and might |
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710 | be well worth enabling it \- if it isn't available in your kernel this will |
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711 | be detected and this backend will be skipped. |
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712 | .Sp |
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713 | This backend can batch oneshot requests and supports a user-space ring |
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714 | buffer to receive events. It also doesn't suffer from most of the design |
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715 | problems of epoll (such as not being able to remove event sources from |
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716 | the epoll set), and generally sounds too good to be true. Because, this |
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717 | being the linux kernel, of course it suffers from a whole new set of |
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718 | limitations. |
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719 | .Sp |
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720 | For one, it is not easily embeddable (but probably could be done using |
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721 | an event fd at some extra overhead). It also is subject to a system wide |
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722 | limit that can be configured in \fI/proc/sys/fs/aio\-max\-nr\fR \- each loop |
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723 | currently requires \f(CW61\fR of this number. If no aio requests are left, this |
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724 | backend will be skipped during initialisation. |
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725 | .Sp |
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726 | Most problematic in practise, however, is that not all file descriptors |
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727 | work with it. For example, in linux 5.1, tcp sockets, pipes, event fds, |
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728 | files, \fI/dev/null\fR and a few others are supported, but ttys do not work |
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729 | (probably because of a bug), so this is not (yet?) a generic event polling |
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730 | interface. |
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731 | .Sp |
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732 | To work around this latter problem, the current version of libev uses |
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733 | epoll as a fallback for file deescriptor types that do not work. Epoll |
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734 | is used in, kind of, slow mode that hopefully avoids most of its design |
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735 | problems and requires 1\-3 extra syscalls per active fd every iteration. |
677 | .Sp |
736 | .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 |
737 | 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. |
738 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
680 | .ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 |
739 | .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 |
740 | .el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 |
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785 | used if available. |
844 | used if available. |
786 | .Sp |
845 | .Sp |
787 | .Vb 1 |
846 | .Vb 1 |
788 | \& struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE); |
847 | \& struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE); |
789 | .Ve |
848 | .Ve |
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849 | .Sp |
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850 | Example: Similarly, on linux, you mgiht want to take advantage of the |
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851 | linux aio backend if possible, but fall back to something else if that |
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852 | isn't available. |
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853 | .Sp |
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854 | .Vb 1 |
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855 | \& struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_LINUXAIO); |
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856 | .Ve |
790 | .RE |
857 | .RE |
791 | .IP "ev_loop_destroy (loop)" 4 |
858 | .IP "ev_loop_destroy (loop)" 4 |
792 | .IX Item "ev_loop_destroy (loop)" |
859 | .IX Item "ev_loop_destroy (loop)" |
793 | Destroys an event loop object (frees all memory and kernel state |
860 | 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 |
861 | etc.). None of the active event watchers will be stopped in the normal |
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810 | except in the rare occasion where you really need to free its resources. |
877 | 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 |
878 | 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. |
879 | and \f(CW\*(C`ev_loop_destroy\*(C'\fR. |
813 | .IP "ev_loop_fork (loop)" 4 |
880 | .IP "ev_loop_fork (loop)" 4 |
814 | .IX Item "ev_loop_fork (loop)" |
881 | .IX Item "ev_loop_fork (loop)" |
815 | This function sets a flag that causes subsequent \f(CW\*(C`ev_run\*(C'\fR iterations to |
882 | 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 |
883 | 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 |
884 | 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 |
885 | 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. |
886 | sense after forking, in the child process. You \fImust\fR call it (or use |
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887 | \&\f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR) in the child before resuming or calling \f(CW\*(C`ev_run\*(C'\fR. |
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888 | .Sp |
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889 | In addition, if you want to reuse a loop (via this function or |
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890 | \&\f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR), you \fIalso\fR have to ignore \f(CW\*(C`SIGPIPE\*(C'\fR. |
820 | .Sp |
891 | .Sp |
821 | Again, you \fIhave\fR to call it on \fIany\fR loop that you want to re-use after |
892 | 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 |
893 | 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 |
894 | because some kernel interfaces *cough* \fIkqueue\fR *cough* do funny things |
824 | during fork. |
895 | during fork. |
… | |
… | |
1360 | bug in your program. |
1431 | bug in your program. |
1361 | .Sp |
1432 | .Sp |
1362 | Libev will usually signal a few \*(L"dummy\*(R" events together with an error, for |
1433 | 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 |
1434 | 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 |
1435 | 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 |
1436 | 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 |
1437 | programs, though, as the fd could already be closed and reused for another |
1367 | thing, so beware. |
1438 | thing, so beware. |
1368 | .SS "\s-1GENERIC WATCHER FUNCTIONS\s0" |
1439 | .SS "\s-1GENERIC WATCHER FUNCTIONS\s0" |
1369 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
1440 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
1370 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
1441 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
… | |
… | |
1721 | But really, best use non-blocking mode. |
1792 | But really, best use non-blocking mode. |
1722 | .PP |
1793 | .PP |
1723 | \fIThe special problem of disappearing file descriptors\fR |
1794 | \fIThe special problem of disappearing file descriptors\fR |
1724 | .IX Subsection "The special problem of disappearing file descriptors" |
1795 | .IX Subsection "The special problem of disappearing file descriptors" |
1725 | .PP |
1796 | .PP |
1726 | Some backends (e.g. kqueue, epoll) need to be told about closing a file |
1797 | 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, |
1798 | 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 |
1799 | 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 |
1800 | 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 |
1801 | 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 |
1802 | is registered with libev, there is no efficient way to see that this is, |
1732 | fact, a different file descriptor. |
1803 | in fact, a different file descriptor. |
1733 | .PP |
1804 | .PP |
1734 | To avoid having to explicitly tell libev about such cases, libev follows |
1805 | 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 |
1806 | 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 |
1807 | 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 |
1808 | it is assumed that the file descriptor stays the same. That means that |
… | |
… | |
1789 | reuse the same code path. |
1860 | reuse the same code path. |
1790 | .PP |
1861 | .PP |
1791 | \fIThe special problem of fork\fR |
1862 | \fIThe special problem of fork\fR |
1792 | .IX Subsection "The special problem of fork" |
1863 | .IX Subsection "The special problem of fork" |
1793 | .PP |
1864 | .PP |
1794 | Some backends (epoll, kqueue) do not support \f(CW\*(C`fork ()\*(C'\fR at all or exhibit |
1865 | Some backends (epoll, kqueue, probably linuxaio) do not support \f(CW\*(C`fork ()\*(C'\fR |
1795 | useless behaviour. Libev fully supports fork, but needs to be told about |
1866 | 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. |
1867 | to be told about it in the child if you want to continue to use it in the |
|
|
1868 | child. |
1797 | .PP |
1869 | .PP |
1798 | To support fork in your child processes, you have to call \f(CW\*(C`ev_loop_fork |
1870 | 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 |
1871 | ()\*(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. |
1872 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
1801 | .PP |
1873 | .PP |
… | |
… | |
1806 | when writing to a pipe whose other end has been closed, your program gets |
1878 | 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 |
1879 | 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. |
1880 | this is sensible behaviour, for daemons, this is usually undesirable. |
1809 | .PP |
1881 | .PP |
1810 | So when you encounter spurious, unexplained daemon exits, make sure you |
1882 | 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 |
1883 | 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). |
1884 | somewhere, as that would have given you a big clue). |
1813 | .PP |
1885 | .PP |
1814 | \fIThe special problem of \fIaccept()\fIing when you can't\fR |
1886 | \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" |
1887 | .IX Subsection "The special problem of accept()ing when you can't" |
1816 | .PP |
1888 | .PP |
1817 | Many implementations of the \s-1POSIX \s0\f(CW\*(C`accept\*(C'\fR function (for example, |
1889 | 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 |
1890 | found in post\-2004 Linux) have the peculiar behaviour of not removing a |
1819 | connection from the pending queue in all error cases. |
1891 | connection from the pending queue in all error cases. |
1820 | .PP |
1892 | .PP |
1821 | For example, larger servers often run out of file descriptors (because |
1893 | 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 |
1894 | of resource limits), causing \f(CW\*(C`accept\*(C'\fR to fail with \f(CW\*(C`ENFILE\*(C'\fR but not |
… | |
… | |
2161 | .PP |
2233 | .PP |
2162 | The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR |
2234 | 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 |
2235 | 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 |
2236 | 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 |
2237 | 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: |
2238 | timeout on the current time, use something like the following to adjust |
|
|
2239 | for it: |
2167 | .PP |
2240 | .PP |
2168 | .Vb 1 |
2241 | .Vb 1 |
2169 | \& ev_timer_set (&timer, after + ev_now () \- ev_time (), 0.); |
2242 | \& ev_timer_set (&timer, after + (ev_time () \- ev_now ()), 0.); |
2170 | .Ve |
2243 | .Ve |
2171 | .PP |
2244 | .PP |
2172 | If the event loop is suspended for a long time, you can also force an |
2245 | 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 |
2246 | update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update |
2174 | ()\*(C'\fR. |
2247 | ()\*(C'\fR, although that will push the event time of all outstanding events |
|
|
2248 | further into the future. |
2175 | .PP |
2249 | .PP |
2176 | \fIThe special problem of unsynchronised clocks\fR |
2250 | \fIThe special problem of unsynchronised clocks\fR |
2177 | .IX Subsection "The special problem of unsynchronised clocks" |
2251 | .IX Subsection "The special problem of unsynchronised clocks" |
2178 | .PP |
2252 | .PP |
2179 | Modern systems have a variety of clocks \- libev itself uses the normal |
2253 | 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)" |
2318 | .IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" |
2245 | .PD 0 |
2319 | .PD 0 |
2246 | .IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4 |
2320 | .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)" |
2321 | .IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" |
2248 | .PD |
2322 | .PD |
2249 | Configure the timer to trigger after \f(CW\*(C`after\*(C'\fR seconds. If \f(CW\*(C`repeat\*(C'\fR |
2323 | 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 |
2324 | 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 |
2325 | 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, |
2326 | then the timer will automatically be configured to trigger again \f(CW\*(C`repeat\*(C'\fR |
2253 | until stopped manually. |
2327 | seconds later, again, and again, until stopped manually. |
2254 | .Sp |
2328 | .Sp |
2255 | The timer itself will do a best-effort at avoiding drift, that is, if |
2329 | 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 |
2330 | 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 |
2331 | 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 |
2332 | 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 |
2414 | Periodic watchers are also timers of a kind, but they are very versatile |
2341 | (and unfortunately a bit complex). |
2415 | (and unfortunately a bit complex). |
2342 | .PP |
2416 | .PP |
2343 | Unlike \f(CW\*(C`ev_timer\*(C'\fR, periodic watchers are not based on real time (or |
2417 | 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 |
2418 | 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 |
2419 | (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 |
2420 | 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 |
2421 | time, and time jumps are not uncommon (e.g. when you adjust your |
2348 | wrist-watch). |
2422 | wrist-watch). |
2349 | .PP |
2423 | .PP |
2350 | You can tell a periodic watcher to trigger after some specific point |
2424 | 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 |
2429 | \&\f(CW\*(C`ev_timer\*(C'\fR, which would still trigger roughly 10 seconds after starting |
2356 | it, as it uses a relative timeout). |
2430 | it, as it uses a relative timeout). |
2357 | .PP |
2431 | .PP |
2358 | \&\f(CW\*(C`ev_periodic\*(C'\fR watchers can also be used to implement vastly more complex |
2432 | \&\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 |
2433 | 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 |
2434 | other complicated rules. This cannot easily be done with \f(CW\*(C`ev_timer\*(C'\fR |
2361 | those cannot react to time jumps. |
2435 | watchers, as those cannot react to time jumps. |
2362 | .PP |
2436 | .PP |
2363 | As with timers, the callback is guaranteed to be invoked only when the |
2437 | 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 |
2438 | 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 |
2439 | 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 |
2440 | 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 |
2501 | 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 |
2502 | ignored. Instead, each time the periodic watcher gets scheduled, the |
2429 | reschedule callback will be called with the watcher as first, and the |
2503 | reschedule callback will be called with the watcher as first, and the |
2430 | current time as second argument. |
2504 | current time as second argument. |
2431 | .Sp |
2505 | .Sp |
2432 | \&\s-1NOTE: \s0\fIThis callback \s-1MUST NOT\s0 stop or destroy any periodic watcher, ever, |
2506 | \&\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 |
2507 | or make \s-1ANY\s0 other event loop modifications whatsoever, unless explicitly |
2434 | allowed by documentation here\fR. |
2508 | allowed by documentation here\fR. |
2435 | .Sp |
2509 | .Sp |
2436 | If you need to stop it, return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop |
2510 | 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 |
2511 | 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 |
2525 | 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 |
2526 | (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 |
2527 | will usually be called just before the callback will be triggered, but |
2454 | might be called at other times, too. |
2528 | might be called at other times, too. |
2455 | .Sp |
2529 | .Sp |
2456 | \&\s-1NOTE: \s0\fIThis callback must always return a time that is higher than or |
2530 | \&\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. |
2531 | equal to the passed \f(CI\*(C`now\*(C'\fI value\fR. |
2458 | .Sp |
2532 | .Sp |
2459 | This can be used to create very complex timers, such as a timer that |
2533 | 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 |
2534 | 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 |
2535 | 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 |
2536 | this. Here is a (completely untested, no error checking) example on how to |
2463 | reason I omitted it as an example). |
2537 | do this: |
|
|
2538 | .Sp |
|
|
2539 | .Vb 1 |
|
|
2540 | \& #include <time.h> |
|
|
2541 | \& |
|
|
2542 | \& static ev_tstamp |
|
|
2543 | \& my_rescheduler (ev_periodic *w, ev_tstamp now) |
|
|
2544 | \& { |
|
|
2545 | \& time_t tnow = (time_t)now; |
|
|
2546 | \& struct tm tm; |
|
|
2547 | \& localtime_r (&tnow, &tm); |
|
|
2548 | \& |
|
|
2549 | \& tm.tm_sec = tm.tm_min = tm.tm_hour = 0; // midnight current day |
|
|
2550 | \& ++tm.tm_mday; // midnight next day |
|
|
2551 | \& |
|
|
2552 | \& return mktime (&tm); |
|
|
2553 | \& } |
|
|
2554 | .Ve |
|
|
2555 | .Sp |
|
|
2556 | Note: this code might run into trouble on days that have more then two |
|
|
2557 | midnights (beginning and end). |
2464 | .RE |
2558 | .RE |
2465 | .RS 4 |
2559 | .RS 4 |
2466 | .RE |
2560 | .RE |
2467 | .IP "ev_periodic_again (loop, ev_periodic *)" 4 |
2561 | .IP "ev_periodic_again (loop, ev_periodic *)" 4 |
2468 | .IX Item "ev_periodic_again (loop, ev_periodic *)" |
2562 | .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 |
2647 | 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 |
2648 | 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 |
2649 | \&\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. |
2650 | the moment, \f(CW\*(C`SIGCHLD\*(C'\fR is permanently tied to the default loop. |
2557 | .PP |
2651 | .PP |
2558 | When the first watcher gets started will libev actually register something |
2652 | 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 |
2653 | register something with the kernel. It thus coexists with your own signal |
2560 | you don't register any with libev for the same signal). |
2654 | handlers as long as you don't register any with libev for the same signal. |
2561 | .PP |
2655 | .PP |
2562 | If possible and supported, libev will install its handlers with |
2656 | 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 |
2657 | \&\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 |
2658 | 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 |
2659 | 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 |
2680 | 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 |
2681 | 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. |
2682 | catch fork calls done by libraries (such as the libc) as well. |
2589 | .PP |
2683 | .PP |
2590 | In current versions of libev, the signal will not be blocked indefinitely |
2684 | 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 |
2685 | 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 |
2686 | the window of opportunity for problems, it will not go away, as libev |
2593 | \&\fIhas\fR to modify the signal mask, at least temporarily. |
2687 | \&\fIhas\fR to modify the signal mask, at least temporarily. |
2594 | .PP |
2688 | .PP |
2595 | So I can't stress this enough: \fIIf you do not reset your signal mask when |
2689 | 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 |
2690 | 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!" |
3142 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
3049 | Prepare and check watchers are often (but not always) used in pairs: |
3143 | Prepare and check watchers are often (but not always) used in pairs: |
3050 | prepare watchers get invoked before the process blocks and check watchers |
3144 | prepare watchers get invoked before the process blocks and check watchers |
3051 | afterwards. |
3145 | afterwards. |
3052 | .PP |
3146 | .PP |
3053 | You \fImust not\fR call \f(CW\*(C`ev_run\*(C'\fR or similar functions that enter |
3147 | 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 |
3148 | 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 |
3149 | \&\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 |
3150 | 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, |
3151 | 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 |
3152 | \&\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. |
3153 | kind they will always be called in pairs bracketing the blocking call. |
3060 | .PP |
3154 | .PP |
3061 | Their main purpose is to integrate other event mechanisms into libev and |
3155 | 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 |
3156 | 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 |
3157 | variable changes, implement your own watchers, integrate net-snmp or a |
3064 | coroutine library and lots more. They are also occasionally useful if |
3158 | coroutine library and lots more. They are also occasionally useful if |
… | |
… | |
3358 | .PP |
3452 | .PP |
3359 | .Vb 3 |
3453 | .Vb 3 |
3360 | \& struct ev_loop *loop_hi = ev_default_init (0); |
3454 | \& struct ev_loop *loop_hi = ev_default_init (0); |
3361 | \& struct ev_loop *loop_lo = 0; |
3455 | \& struct ev_loop *loop_lo = 0; |
3362 | \& ev_embed embed; |
3456 | \& ev_embed embed; |
3363 | \& |
3457 | \& |
3364 | \& // see if there is a chance of getting one that works |
3458 | \& // see if there is a chance of getting one that works |
3365 | \& // (remember that a flags value of 0 means autodetection) |
3459 | \& // (remember that a flags value of 0 means autodetection) |
3366 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3460 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3367 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3461 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3368 | \& : 0; |
3462 | \& : 0; |
… | |
… | |
3384 | .PP |
3478 | .PP |
3385 | .Vb 3 |
3479 | .Vb 3 |
3386 | \& struct ev_loop *loop = ev_default_init (0); |
3480 | \& struct ev_loop *loop = ev_default_init (0); |
3387 | \& struct ev_loop *loop_socket = 0; |
3481 | \& struct ev_loop *loop_socket = 0; |
3388 | \& ev_embed embed; |
3482 | \& ev_embed embed; |
3389 | \& |
3483 | \& |
3390 | \& if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3484 | \& if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3391 | \& if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3485 | \& if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3392 | \& { |
3486 | \& { |
3393 | \& ev_embed_init (&embed, 0, loop_socket); |
3487 | \& ev_embed_init (&embed, 0, loop_socket); |
3394 | \& ev_embed_start (loop, &embed); |
3488 | \& ev_embed_start (loop, &embed); |
… | |
… | |
3411 | of course. |
3505 | of course. |
3412 | .PP |
3506 | .PP |
3413 | \fIThe special problem of life after fork \- how is it possible?\fR |
3507 | \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?" |
3508 | .IX Subsection "The special problem of life after fork - how is it possible?" |
3415 | .PP |
3509 | .PP |
3416 | Most uses of \f(CW\*(C`fork()\*(C'\fR consist of forking, then some simple calls to set |
3510 | 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 |
3511 | 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. |
3512 | sequence should be handled by libev without any problems. |
3419 | .PP |
3513 | .PP |
3420 | This changes when the application actually wants to do event handling |
3514 | 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 |
3515 | 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 |
3732 | is a time window between the event loop checking and resetting the async |
3639 | notification, and the callback being invoked. |
3733 | notification, and the callback being invoked. |
3640 | .SH "OTHER FUNCTIONS" |
3734 | .SH "OTHER FUNCTIONS" |
3641 | .IX Header "OTHER FUNCTIONS" |
3735 | .IX Header "OTHER FUNCTIONS" |
3642 | There are some other functions of possible interest. Described. Here. Now. |
3736 | 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 |
3737 | .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)" |
3738 | .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 |
3739 | This function combines a simple timer and an I/O watcher, calls your |
3646 | callback on whichever event happens first and automatically stops both |
3740 | 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 |
3741 | 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 |
3742 | or timeout without having to allocate/configure/start/stop/free one or |
3649 | more watchers yourself. |
3743 | more watchers yourself. |
… | |
… | |
4049 | files, \fImy_ev.h\fR and \fImy_ev.c\fR that include the respective libev files: |
4143 | files, \fImy_ev.h\fR and \fImy_ev.c\fR that include the respective libev files: |
4050 | .PP |
4144 | .PP |
4051 | .Vb 4 |
4145 | .Vb 4 |
4052 | \& // my_ev.h |
4146 | \& // my_ev.h |
4053 | \& #define EV_CB_DECLARE(type) struct my_coro *cb; |
4147 | \& #define EV_CB_DECLARE(type) struct my_coro *cb; |
4054 | \& #define EV_CB_INVOKE(watcher) switch_to ((watcher)\->cb); |
4148 | \& #define EV_CB_INVOKE(watcher) switch_to ((watcher)\->cb) |
4055 | \& #include "../libev/ev.h" |
4149 | \& #include "../libev/ev.h" |
4056 | \& |
4150 | \& |
4057 | \& // my_ev.c |
4151 | \& // my_ev.c |
4058 | \& #define EV_H "my_ev.h" |
4152 | \& #define EV_H "my_ev.h" |
4059 | \& #include "../libev/ev.c" |
4153 | \& #include "../libev/ev.c" |
… | |
… | |
4099 | The normal C \s-1API\s0 should work fine when used from \*(C+: both ev.h and the |
4193 | 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 |
4194 | libev sources can be compiled as \*(C+. Therefore, code that uses the C \s-1API\s0 |
4101 | will work fine. |
4195 | will work fine. |
4102 | .PP |
4196 | .PP |
4103 | Proper exception specifications might have to be added to callbacks passed |
4197 | Proper exception specifications might have to be added to callbacks passed |
4104 | to libev: exceptions may be thrown only from watcher callbacks, all |
4198 | to libev: exceptions may be thrown only from watcher callbacks, all other |
4105 | other callbacks (allocator, syserr, loop acquire/release and periodic |
4199 | callbacks (allocator, syserr, loop acquire/release and periodic reschedule |
4106 | reschedule callbacks) must not throw exceptions, and might need a \f(CW\*(C`throw |
4200 | 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 |
4201 | 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: |
4202 | \&\*(C+ you can use the \f(CW\*(C`EV_NOEXCEPT\*(C'\fR macro for this: |
4109 | .PP |
4203 | .PP |
4110 | .Vb 6 |
4204 | .Vb 6 |
4111 | \& static void |
4205 | \& static void |
4112 | \& fatal_error (const char *msg) EV_THROW |
4206 | \& fatal_error (const char *msg) EV_NOEXCEPT |
4113 | \& { |
4207 | \& { |
4114 | \& perror (msg); |
4208 | \& perror (msg); |
4115 | \& abort (); |
4209 | \& abort (); |
4116 | \& } |
4210 | \& } |
4117 | \& |
4211 | \& |
… | |
… | |
4245 | \& void operator() (ev::io &w, int revents) |
4339 | \& void operator() (ev::io &w, int revents) |
4246 | \& { |
4340 | \& { |
4247 | \& ... |
4341 | \& ... |
4248 | \& } |
4342 | \& } |
4249 | \& } |
4343 | \& } |
4250 | \& |
4344 | \& |
4251 | \& myfunctor f; |
4345 | \& myfunctor f; |
4252 | \& |
4346 | \& |
4253 | \& ev::io w; |
4347 | \& ev::io w; |
4254 | \& w.set (&f); |
4348 | \& w.set (&f); |
4255 | .Ve |
4349 | .Ve |
… | |
… | |
4491 | \& #include "ev.c" |
4585 | \& #include "ev.c" |
4492 | .Ve |
4586 | .Ve |
4493 | .PP |
4587 | .PP |
4494 | This will automatically include \fIev.h\fR, too, and should be done in a |
4588 | 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 |
4589 | 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 |
4590 | 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 |
4591 | done by writing a wrapper around \fIev.h\fR that you can include instead and |
4498 | where you can put other configuration options): |
4592 | where you can put other configuration options): |
4499 | .PP |
4593 | .PP |
4500 | .Vb 2 |
4594 | .Vb 2 |
4501 | \& #define EV_STANDALONE 1 |
4595 | \& #define EV_STANDALONE 1 |
… | |
… | |
4515 | \& ev_vars.h |
4609 | \& ev_vars.h |
4516 | \& ev_wrap.h |
4610 | \& ev_wrap.h |
4517 | \& |
4611 | \& |
4518 | \& ev_win32.c required on win32 platforms only |
4612 | \& ev_win32.c required on win32 platforms only |
4519 | \& |
4613 | \& |
4520 | \& ev_select.c only when select backend is enabled (which is enabled by default) |
4614 | \& ev_select.c only when select backend is enabled |
4521 | \& ev_poll.c only when poll backend is enabled (disabled by default) |
4615 | \& ev_poll.c only when poll backend is enabled |
4522 | \& ev_epoll.c only when the epoll backend is enabled (disabled by default) |
4616 | \& ev_epoll.c only when the epoll backend is enabled |
|
|
4617 | \& ev_linuxaio.c only when the linux aio backend is enabled |
4523 | \& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
4618 | \& 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) |
4619 | \& ev_port.c only when the solaris port backend is enabled |
4525 | .Ve |
4620 | .Ve |
4526 | .PP |
4621 | .PP |
4527 | \&\fIev.c\fR includes the backend files directly when enabled, so you only need |
4622 | \&\fIev.c\fR includes the backend files directly when enabled, so you only need |
4528 | to compile this single file. |
4623 | to compile this single file. |
4529 | .PP |
4624 | .PP |
… | |
… | |
4574 | values when compiling libev vs. including \fIev.h\fR, so it is permissible |
4669 | 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 |
4670 | 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 |
4671 | 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 |
4672 | users of libev and the libev code itself must be compiled with compatible |
4578 | settings. |
4673 | settings. |
4579 | .IP "\s-1EV_COMPAT3 \s0(h)" 4 |
4674 | .IP "\s-1EV_COMPAT3\s0 (h)" 4 |
4580 | .IX Item "EV_COMPAT3 (h)" |
4675 | .IX Item "EV_COMPAT3 (h)" |
4581 | Backwards compatibility is a major concern for libev. This is why this |
4676 | 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 |
4677 | release of libev comes with wrappers for the functions and symbols that |
4583 | have been renamed between libev version 3 and 4. |
4678 | have been renamed between libev version 3 and 4. |
4584 | .Sp |
4679 | .Sp |
… | |
… | |
4589 | typedef in that case. |
4684 | typedef in that case. |
4590 | .Sp |
4685 | .Sp |
4591 | In some future version, the default for \f(CW\*(C`EV_COMPAT3\*(C'\fR will become \f(CW0\fR, |
4686 | 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 |
4687 | and in some even more future version the compatibility code will be |
4593 | removed completely. |
4688 | removed completely. |
4594 | .IP "\s-1EV_STANDALONE \s0(h)" 4 |
4689 | .IP "\s-1EV_STANDALONE\s0 (h)" 4 |
4595 | .IX Item "EV_STANDALONE (h)" |
4690 | .IX Item "EV_STANDALONE (h)" |
4596 | Must always be \f(CW1\fR if you do not use autoconf configuration, which |
4691 | 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 |
4692 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
4598 | implementations for some libevent functions (such as logging, which is not |
4693 | 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 |
4694 | supported). It will also not define any of the structs usually found in |
… | |
… | |
4708 | If defined to be \f(CW1\fR, libev will compile in support for the Linux |
4803 | 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, |
4804 | \&\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 |
4805 | 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 |
4806 | 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. |
4807 | headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
|
|
4808 | .IP "\s-1EV_USE_LINUXAIO\s0" 4 |
|
|
4809 | .IX Item "EV_USE_LINUXAIO" |
|
|
4810 | If defined to be \f(CW1\fR, libev will compile in support for the Linux |
|
|
4811 | aio backend. Due to it's currenbt limitations it has to be requested |
|
|
4812 | explicitly. If undefined, it will be enabled on linux, otherwise |
|
|
4813 | disabled. |
4713 | .IP "\s-1EV_USE_KQUEUE\s0" 4 |
4814 | .IP "\s-1EV_USE_KQUEUE\s0" 4 |
4714 | .IX Item "EV_USE_KQUEUE" |
4815 | .IX Item "EV_USE_KQUEUE" |
4715 | If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style |
4816 | 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, |
4817 | \&\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 |
4818 | 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 |
4858 | handler \*(L"locking\*(R" as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR |
4758 | watchers. |
4859 | watchers. |
4759 | .Sp |
4860 | .Sp |
4760 | In the absence of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR |
4861 | 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. |
4862 | (from \fIsignal.h\fR), which is usually good enough on most platforms. |
4762 | .IP "\s-1EV_H \s0(h)" 4 |
4863 | .IP "\s-1EV_H\s0 (h)" 4 |
4763 | .IX Item "EV_H (h)" |
4864 | .IX Item "EV_H (h)" |
4764 | The name of the \fIev.h\fR header file used to include it. The default if |
4865 | 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 |
4866 | 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. |
4867 | used to virtually rename the \fIev.h\fR header file in case of conflicts. |
4767 | .IP "\s-1EV_CONFIG_H \s0(h)" 4 |
4868 | .IP "\s-1EV_CONFIG_H\s0 (h)" 4 |
4768 | .IX Item "EV_CONFIG_H (h)" |
4869 | .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 |
4870 | 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 |
4871 | \&\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. |
4872 | \&\f(CW\*(C`EV_H\*(C'\fR, above. |
4772 | .IP "\s-1EV_EVENT_H \s0(h)" 4 |
4873 | .IP "\s-1EV_EVENT_H\s0 (h)" 4 |
4773 | .IX Item "EV_EVENT_H (h)" |
4874 | .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 |
4875 | 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. |
4876 | 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 |
4877 | .IP "\s-1EV_PROTOTYPES\s0 (h)" 4 |
4777 | .IX Item "EV_PROTOTYPES (h)" |
4878 | .IX Item "EV_PROTOTYPES (h)" |
4778 | If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function |
4879 | 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 |
4880 | prototypes, but still define all the structs and other symbols. This is |
4780 | occasionally useful if you want to provide your own wrapper functions |
4881 | occasionally useful if you want to provide your own wrapper functions |
4781 | around libev functions. |
4882 | around libev functions. |
… | |
… | |
4990 | .Vb 3 |
5091 | .Vb 3 |
4991 | \& #define EV_COMMON \e |
5092 | \& #define EV_COMMON \e |
4992 | \& SV *self; /* contains this struct */ \e |
5093 | \& SV *self; /* contains this struct */ \e |
4993 | \& SV *cb_sv, *fh /* note no trailing ";" */ |
5094 | \& SV *cb_sv, *fh /* note no trailing ";" */ |
4994 | .Ve |
5095 | .Ve |
4995 | .IP "\s-1EV_CB_DECLARE \s0(type)" 4 |
5096 | .IP "\s-1EV_CB_DECLARE\s0 (type)" 4 |
4996 | .IX Item "EV_CB_DECLARE (type)" |
5097 | .IX Item "EV_CB_DECLARE (type)" |
4997 | .PD 0 |
5098 | .PD 0 |
4998 | .IP "\s-1EV_CB_INVOKE \s0(watcher, revents)" 4 |
5099 | .IP "\s-1EV_CB_INVOKE\s0 (watcher, revents)" 4 |
4999 | .IX Item "EV_CB_INVOKE (watcher, revents)" |
5100 | .IX Item "EV_CB_INVOKE (watcher, revents)" |
5000 | .IP "ev_set_cb (ev, cb)" 4 |
5101 | .IP "ev_set_cb (ev, cb)" 4 |
5001 | .IX Item "ev_set_cb (ev, cb)" |
5102 | .IX Item "ev_set_cb (ev, cb)" |
5002 | .PD |
5103 | .PD |
5003 | Can be used to change the callback member declaration in each watcher, |
5104 | Can be used to change the callback member declaration in each watcher, |
… | |
… | |
5006 | their default definitions. One possible use for overriding these is to |
5107 | 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 |
5108 | 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+. |
5109 | method calls instead of plain function calls in \*(C+. |
5009 | .SS "\s-1EXPORTED API SYMBOLS\s0" |
5110 | .SS "\s-1EXPORTED API SYMBOLS\s0" |
5010 | .IX Subsection "EXPORTED API SYMBOLS" |
5111 | .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 |
5112 | 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 |
5113 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
5013 | all public symbols, one per line: |
5114 | all public symbols, one per line: |
5014 | .PP |
5115 | .PP |
5015 | .Vb 2 |
5116 | .Vb 2 |
5016 | \& Symbols.ev for libev proper |
5117 | \& Symbols.ev for libev proper |
… | |
… | |
5248 | .PP |
5349 | .PP |
5249 | \fI\f(CI\*(C`select\*(C'\fI is buggy\fR |
5350 | \fI\f(CI\*(C`select\*(C'\fI is buggy\fR |
5250 | .IX Subsection "select is buggy" |
5351 | .IX Subsection "select is buggy" |
5251 | .PP |
5352 | .PP |
5252 | All that's left is \f(CW\*(C`select\*(C'\fR, and of course Apple found a way to fuck this |
5353 | 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 |
5354 | 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 |
5355 | descriptors you can pass in to 1024 \- your program suddenly crashes when |
5255 | you use more. |
5356 | you use more. |
5256 | .PP |
5357 | .PP |
5257 | There is an undocumented \*(L"workaround\*(R" for this \- defining |
5358 | 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 |
5359 | \&\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 |
5507 | 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 |
5508 | 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 |
5509 | assumes that the same (machine) code can be used to call any watcher |
5409 | callback: The watcher callbacks have different type signatures, but libev |
5510 | callback: The watcher callbacks have different type signatures, but libev |
5410 | calls them using an \f(CW\*(C`ev_watcher *\*(C'\fR internally. |
5511 | calls them using an \f(CW\*(C`ev_watcher *\*(C'\fR internally. |
|
|
5512 | .IP "null pointers and integer zero are represented by 0 bytes" 4 |
|
|
5513 | .IX Item "null pointers and integer zero are represented by 0 bytes" |
|
|
5514 | Libev uses \f(CW\*(C`memset\*(C'\fR to initialise structs and arrays to \f(CW0\fR bytes, and |
|
|
5515 | relies on this setting pointers and integers to null. |
5411 | .IP "pointer accesses must be thread-atomic" 4 |
5516 | .IP "pointer accesses must be thread-atomic" 4 |
5412 | .IX Item "pointer accesses must be thread-atomic" |
5517 | .IX Item "pointer accesses must be thread-atomic" |
5413 | Accessing a pointer value must be atomic, it must both be readable and |
5518 | 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. |
5519 | 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 |
5520 | .ie n .IP """sig_atomic_t volatile"" must be thread-atomic as well" 4 |