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1 | =encoding utf-8 |
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2 | |
1 | =head1 NAME |
3 | =head1 NAME |
2 | |
4 | |
3 | libev - a high performance full-featured event loop written in C |
5 | libev - a high performance full-featured event loop written in C |
4 | |
6 | |
5 | =head1 SYNOPSIS |
7 | =head1 SYNOPSIS |
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103 | details of the event, and then hand it over to libev by I<starting> the |
105 | details of the event, and then hand it over to libev by I<starting> the |
104 | watcher. |
106 | watcher. |
105 | |
107 | |
106 | =head2 FEATURES |
108 | =head2 FEATURES |
107 | |
109 | |
108 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
110 | Libev supports C<select>, C<poll>, the Linux-specific aio and C<epoll> |
109 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
111 | interfaces, the BSD-specific C<kqueue> and the Solaris-specific event port |
110 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
112 | mechanisms for file descriptor events (C<ev_io>), the Linux C<inotify> |
111 | (for C<ev_stat>), Linux eventfd/signalfd (for faster and cleaner |
113 | interface (for C<ev_stat>), Linux eventfd/signalfd (for faster and cleaner |
112 | inter-thread wakeup (C<ev_async>)/signal handling (C<ev_signal>)) relative |
114 | inter-thread wakeup (C<ev_async>)/signal handling (C<ev_signal>)) relative |
113 | timers (C<ev_timer>), absolute timers with customised rescheduling |
115 | timers (C<ev_timer>), absolute timers with customised rescheduling |
114 | (C<ev_periodic>), synchronous signals (C<ev_signal>), process status |
116 | (C<ev_periodic>), synchronous signals (C<ev_signal>), process status |
115 | change events (C<ev_child>), and event watchers dealing with the event |
117 | change events (C<ev_child>), and event watchers dealing with the event |
116 | loop mechanism itself (C<ev_idle>, C<ev_embed>, C<ev_prepare> and |
118 | loop mechanism itself (C<ev_idle>, C<ev_embed>, C<ev_prepare> and |
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263 | |
265 | |
264 | You could override this function in high-availability programs to, say, |
266 | You could override this function in high-availability programs to, say, |
265 | free some memory if it cannot allocate memory, to use a special allocator, |
267 | free some memory if it cannot allocate memory, to use a special allocator, |
266 | or even to sleep a while and retry until some memory is available. |
268 | or even to sleep a while and retry until some memory is available. |
267 | |
269 | |
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270 | Example: The following is the C<realloc> function that libev itself uses |
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271 | which should work with C<realloc> and C<free> functions of all kinds and |
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272 | is probably a good basis for your own implementation. |
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273 | |
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274 | static void * |
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275 | ev_realloc_emul (void *ptr, long size) EV_NOEXCEPT |
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276 | { |
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277 | if (size) |
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278 | return realloc (ptr, size); |
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279 | |
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280 | free (ptr); |
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281 | return 0; |
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282 | } |
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283 | |
268 | Example: Replace the libev allocator with one that waits a bit and then |
284 | Example: Replace the libev allocator with one that waits a bit and then |
269 | retries (example requires a standards-compliant C<realloc>). |
285 | retries. |
270 | |
286 | |
271 | static void * |
287 | static void * |
272 | persistent_realloc (void *ptr, size_t size) |
288 | persistent_realloc (void *ptr, size_t size) |
273 | { |
289 | { |
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290 | if (!size) |
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291 | { |
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292 | free (ptr); |
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293 | return 0; |
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294 | } |
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295 | |
274 | for (;;) |
296 | for (;;) |
275 | { |
297 | { |
276 | void *newptr = realloc (ptr, size); |
298 | void *newptr = realloc (ptr, size); |
277 | |
299 | |
278 | if (newptr) |
300 | if (newptr) |
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396 | |
418 | |
397 | If this flag bit is or'ed into the flag value (or the program runs setuid |
419 | If this flag bit is or'ed into the flag value (or the program runs setuid |
398 | or setgid) then libev will I<not> look at the environment variable |
420 | or setgid) then libev will I<not> look at the environment variable |
399 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
421 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
400 | override the flags completely if it is found in the environment. This is |
422 | override the flags completely if it is found in the environment. This is |
401 | useful to try out specific backends to test their performance, or to work |
423 | useful to try out specific backends to test their performance, to work |
402 | around bugs. |
424 | around bugs, or to make libev threadsafe (accessing environment variables |
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425 | cannot be done in a threadsafe way, but usually it works if no other |
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426 | thread modifies them). |
403 | |
427 | |
404 | =item C<EVFLAG_FORKCHECK> |
428 | =item C<EVFLAG_FORKCHECK> |
405 | |
429 | |
406 | Instead of calling C<ev_loop_fork> manually after a fork, you can also |
430 | Instead of calling C<ev_loop_fork> manually after a fork, you can also |
407 | make libev check for a fork in each iteration by enabling this flag. |
431 | make libev check for a fork in each iteration by enabling this flag. |
408 | |
432 | |
409 | This works by calling C<getpid ()> on every iteration of the loop, |
433 | This works by calling C<getpid ()> on every iteration of the loop, |
410 | and thus this might slow down your event loop if you do a lot of loop |
434 | and thus this might slow down your event loop if you do a lot of loop |
411 | iterations and little real work, but is usually not noticeable (on my |
435 | iterations and little real work, but is usually not noticeable (on my |
412 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
436 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn |
413 | without a system call and thus I<very> fast, but my GNU/Linux system also has |
437 | sequence without a system call and thus I<very> fast, but my GNU/Linux |
414 | C<pthread_atfork> which is even faster). |
438 | system also has C<pthread_atfork> which is even faster). (Update: glibc |
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439 | versions 2.25 apparently removed the C<getpid> optimisation again). |
415 | |
440 | |
416 | The big advantage of this flag is that you can forget about fork (and |
441 | The big advantage of this flag is that you can forget about fork (and |
417 | forget about forgetting to tell libev about forking) when you use this |
442 | forget about forgetting to tell libev about forking, although you still |
418 | flag. |
443 | have to ignore C<SIGPIPE>) when you use this flag. |
419 | |
444 | |
420 | This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS> |
445 | This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS> |
421 | environment variable. |
446 | environment variable. |
422 | |
447 | |
423 | =item C<EVFLAG_NOINOTIFY> |
448 | =item C<EVFLAG_NOINOTIFY> |
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542 | All this means that, in practice, C<EVBACKEND_SELECT> can be as fast or |
567 | All this means that, in practice, C<EVBACKEND_SELECT> can be as fast or |
543 | faster than epoll for maybe up to a hundred file descriptors, depending on |
568 | faster than epoll for maybe up to a hundred file descriptors, depending on |
544 | the usage. So sad. |
569 | the usage. So sad. |
545 | |
570 | |
546 | While nominally embeddable in other event loops, this feature is broken in |
571 | While nominally embeddable in other event loops, this feature is broken in |
547 | all kernel versions tested so far. |
572 | a lot of kernel revisions, but probably(!) works in current versions. |
548 | |
573 | |
549 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
574 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
550 | C<EVBACKEND_POLL>. |
575 | C<EVBACKEND_POLL>. |
551 | |
576 | |
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577 | =item C<EVBACKEND_LINUXAIO> (value 64, Linux) |
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578 | |
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579 | Use the linux-specific linux aio (I<not> C<< aio(7) >> but C<< |
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580 | io_submit(2) >>) event interface available in post-4.18 kernels (but libev |
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581 | only tries to use it in 4.19+). |
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582 | |
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583 | This is another linux trainwreck of an event interface. |
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584 | |
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585 | If this backend works for you (as of this writing, it was very |
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586 | experimental), it is the best event interface available on linux and might |
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587 | be well worth enabling it - if it isn't available in your kernel this will |
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588 | be detected and this backend will be skipped. |
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589 | |
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590 | This backend can batch oneshot requests and supports a user-space ring |
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591 | buffer to receive events. It also doesn't suffer from most of the design |
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592 | problems of epoll (such as not being able to remove event sources from |
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593 | the epoll set), and generally sounds too good to be true. Because, this |
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594 | being the linux kernel, of course it suffers from a whole new set of |
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595 | limitations, forcing you to fall back to epoll, inheriting all its design |
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596 | issues. |
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597 | |
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598 | For one, it is not easily embeddable (but probably could be done using |
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599 | an event fd at some extra overhead). It also is subject to a system wide |
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600 | limit that can be configured in F</proc/sys/fs/aio-max-nr>. If no aio |
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601 | requests are left, this backend will be skipped during initialisation, and |
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602 | will switch to epoll when the loop is active. |
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603 | |
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604 | Most problematic in practice, however, is that not all file descriptors |
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605 | work with it. For example, in linux 5.1, tcp sockets, pipes, event fds, |
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606 | files, F</dev/null> and a few others are supported, but ttys do not work |
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607 | properly (a known bug that the kernel developers don't care about, see |
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608 | L<https://lore.kernel.org/patchwork/patch/1047453/>), so this is not |
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609 | (yet?) a generic event polling interface. |
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610 | |
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611 | Overall, it seems the linux developers just don't want it to have a |
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612 | generic event handling mechanism other than C<select> or C<poll>. |
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613 | |
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614 | To work around all these problem, the current version of libev uses its |
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615 | epoll backend as a fallback for file descriptor types that do not work. Or |
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616 | falls back completely to epoll if the kernel acts up. |
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617 | |
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618 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
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619 | C<EVBACKEND_POLL>. |
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620 | |
552 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
621 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
553 | |
622 | |
554 | Kqueue deserves special mention, as at the time of this writing, it |
623 | Kqueue deserves special mention, as at the time this backend was |
555 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
624 | implemented, it was broken on all BSDs except NetBSD (usually it doesn't |
556 | with anything but sockets and pipes, except on Darwin, where of course |
625 | work reliably with anything but sockets and pipes, except on Darwin, |
557 | it's completely useless). Unlike epoll, however, whose brokenness |
626 | where of course it's completely useless). Unlike epoll, however, whose |
558 | is by design, these kqueue bugs can (and eventually will) be fixed |
627 | brokenness is by design, these kqueue bugs can be (and mostly have been) |
559 | without API changes to existing programs. For this reason it's not being |
628 | fixed without API changes to existing programs. For this reason it's not |
560 | "auto-detected" unless you explicitly specify it in the flags (i.e. using |
629 | being "auto-detected" on all platforms unless you explicitly specify it |
561 | C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough) |
630 | in the flags (i.e. using C<EVBACKEND_KQUEUE>) or libev was compiled on a |
562 | system like NetBSD. |
631 | known-to-be-good (-enough) system like NetBSD. |
563 | |
632 | |
564 | You still can embed kqueue into a normal poll or select backend and use it |
633 | You still can embed kqueue into a normal poll or select backend and use it |
565 | only for sockets (after having made sure that sockets work with kqueue on |
634 | only for sockets (after having made sure that sockets work with kqueue on |
566 | the target platform). See C<ev_embed> watchers for more info. |
635 | the target platform). See C<ev_embed> watchers for more info. |
567 | |
636 | |
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569 | kernel is more efficient (which says nothing about its actual speed, of |
638 | kernel is more efficient (which says nothing about its actual speed, of |
570 | course). While stopping, setting and starting an I/O watcher does never |
639 | course). While stopping, setting and starting an I/O watcher does never |
571 | cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to |
640 | cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to |
572 | two event changes per incident. Support for C<fork ()> is very bad (you |
641 | two event changes per incident. Support for C<fork ()> is very bad (you |
573 | might have to leak fd's on fork, but it's more sane than epoll) and it |
642 | might have to leak fd's on fork, but it's more sane than epoll) and it |
574 | drops fds silently in similarly hard-to-detect cases |
643 | drops fds silently in similarly hard-to-detect cases. |
575 | |
644 | |
576 | This backend usually performs well under most conditions. |
645 | This backend usually performs well under most conditions. |
577 | |
646 | |
578 | While nominally embeddable in other event loops, this doesn't work |
647 | While nominally embeddable in other event loops, this doesn't work |
579 | everywhere, so you might need to test for this. And since it is broken |
648 | everywhere, so you might need to test for this. And since it is broken |
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653 | Example: Use whatever libev has to offer, but make sure that kqueue is |
722 | Example: Use whatever libev has to offer, but make sure that kqueue is |
654 | used if available. |
723 | used if available. |
655 | |
724 | |
656 | struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE); |
725 | struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE); |
657 | |
726 | |
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727 | Example: Similarly, on linux, you mgiht want to take advantage of the |
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728 | linux aio backend if possible, but fall back to something else if that |
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729 | isn't available. |
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730 | |
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731 | struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_LINUXAIO); |
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732 | |
658 | =item ev_loop_destroy (loop) |
733 | =item ev_loop_destroy (loop) |
659 | |
734 | |
660 | Destroys an event loop object (frees all memory and kernel state |
735 | Destroys an event loop object (frees all memory and kernel state |
661 | etc.). None of the active event watchers will be stopped in the normal |
736 | etc.). None of the active event watchers will be stopped in the normal |
662 | sense, so e.g. C<ev_is_active> might still return true. It is your |
737 | sense, so e.g. C<ev_is_active> might still return true. It is your |
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678 | If you need dynamically allocated loops it is better to use C<ev_loop_new> |
753 | If you need dynamically allocated loops it is better to use C<ev_loop_new> |
679 | and C<ev_loop_destroy>. |
754 | and C<ev_loop_destroy>. |
680 | |
755 | |
681 | =item ev_loop_fork (loop) |
756 | =item ev_loop_fork (loop) |
682 | |
757 | |
683 | This function sets a flag that causes subsequent C<ev_run> iterations to |
758 | This function sets a flag that causes subsequent C<ev_run> iterations |
684 | reinitialise the kernel state for backends that have one. Despite the |
759 | to reinitialise the kernel state for backends that have one. Despite |
685 | name, you can call it anytime, but it makes most sense after forking, in |
760 | the name, you can call it anytime you are allowed to start or stop |
686 | the child process. You I<must> call it (or use C<EVFLAG_FORKCHECK>) in the |
761 | watchers (except inside an C<ev_prepare> callback), but it makes most |
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762 | sense after forking, in the child process. You I<must> call it (or use |
687 | child before resuming or calling C<ev_run>. |
763 | C<EVFLAG_FORKCHECK>) in the child before resuming or calling C<ev_run>. |
688 | |
764 | |
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765 | In addition, if you want to reuse a loop (via this function or |
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766 | C<EVFLAG_FORKCHECK>), you I<also> have to ignore C<SIGPIPE>. |
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767 | |
689 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
768 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
690 | a fork, I<even if you do not plan to use the loop in the parent>. This is |
769 | a fork, I<even if you do not plan to use the loop in the parent>. This is |
691 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
770 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
692 | during fork. |
771 | during fork. |
693 | |
772 | |
694 | On the other hand, you only need to call this function in the child |
773 | On the other hand, you only need to call this function in the child |
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1393 | transition between them will be described in more detail - and while these |
1472 | transition between them will be described in more detail - and while these |
1394 | rules might look complicated, they usually do "the right thing". |
1473 | rules might look complicated, they usually do "the right thing". |
1395 | |
1474 | |
1396 | =over 4 |
1475 | =over 4 |
1397 | |
1476 | |
1398 | =item initialiased |
1477 | =item initialised |
1399 | |
1478 | |
1400 | Before a watcher can be registered with the event loop it has to be |
1479 | Before a watcher can be registered with the event loop it has to be |
1401 | initialised. This can be done with a call to C<ev_TYPE_init>, or calls to |
1480 | initialised. This can be done with a call to C<ev_TYPE_init>, or calls to |
1402 | C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
1481 | C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
1403 | |
1482 | |
… | |
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1601 | |
1680 | |
1602 | But really, best use non-blocking mode. |
1681 | But really, best use non-blocking mode. |
1603 | |
1682 | |
1604 | =head3 The special problem of disappearing file descriptors |
1683 | =head3 The special problem of disappearing file descriptors |
1605 | |
1684 | |
1606 | Some backends (e.g. kqueue, epoll) need to be told about closing a file |
1685 | Some backends (e.g. kqueue, epoll, linuxaio) need to be told about closing |
1607 | descriptor (either due to calling C<close> explicitly or any other means, |
1686 | a file descriptor (either due to calling C<close> explicitly or any other |
1608 | such as C<dup2>). The reason is that you register interest in some file |
1687 | means, such as C<dup2>). The reason is that you register interest in some |
1609 | descriptor, but when it goes away, the operating system will silently drop |
1688 | file descriptor, but when it goes away, the operating system will silently |
1610 | this interest. If another file descriptor with the same number then is |
1689 | drop this interest. If another file descriptor with the same number then |
1611 | registered with libev, there is no efficient way to see that this is, in |
1690 | is registered with libev, there is no efficient way to see that this is, |
1612 | fact, a different file descriptor. |
1691 | in fact, a different file descriptor. |
1613 | |
1692 | |
1614 | To avoid having to explicitly tell libev about such cases, libev follows |
1693 | To avoid having to explicitly tell libev about such cases, libev follows |
1615 | the following policy: Each time C<ev_io_set> is being called, libev |
1694 | the following policy: Each time C<ev_io_set> is being called, libev |
1616 | will assume that this is potentially a new file descriptor, otherwise |
1695 | will assume that this is potentially a new file descriptor, otherwise |
1617 | it is assumed that the file descriptor stays the same. That means that |
1696 | it is assumed that the file descriptor stays the same. That means that |
… | |
… | |
1666 | when you rarely read from a file instead of from a socket, and want to |
1745 | when you rarely read from a file instead of from a socket, and want to |
1667 | reuse the same code path. |
1746 | reuse the same code path. |
1668 | |
1747 | |
1669 | =head3 The special problem of fork |
1748 | =head3 The special problem of fork |
1670 | |
1749 | |
1671 | Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit |
1750 | Some backends (epoll, kqueue, probably linuxaio) do not support C<fork ()> |
1672 | useless behaviour. Libev fully supports fork, but needs to be told about |
1751 | at all or exhibit useless behaviour. Libev fully supports fork, but needs |
1673 | it in the child if you want to continue to use it in the child. |
1752 | to be told about it in the child if you want to continue to use it in the |
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1753 | child. |
1674 | |
1754 | |
1675 | To support fork in your child processes, you have to call C<ev_loop_fork |
1755 | To support fork in your child processes, you have to call C<ev_loop_fork |
1676 | ()> after a fork in the child, enable C<EVFLAG_FORKCHECK>, or resort to |
1756 | ()> after a fork in the child, enable C<EVFLAG_FORKCHECK>, or resort to |
1677 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
1757 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
1678 | |
1758 | |
… | |
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2024 | |
2104 | |
2025 | The relative timeouts are calculated relative to the C<ev_now ()> |
2105 | The relative timeouts are calculated relative to the C<ev_now ()> |
2026 | time. This is usually the right thing as this timestamp refers to the time |
2106 | time. This is usually the right thing as this timestamp refers to the time |
2027 | of the event triggering whatever timeout you are modifying/starting. If |
2107 | of the event triggering whatever timeout you are modifying/starting. If |
2028 | you suspect event processing to be delayed and you I<need> to base the |
2108 | you suspect event processing to be delayed and you I<need> to base the |
2029 | timeout on the current time, use something like this to adjust for this: |
2109 | timeout on the current time, use something like the following to adjust |
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2110 | for it: |
2030 | |
2111 | |
2031 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
2112 | ev_timer_set (&timer, after + (ev_time () - ev_now ()), 0.); |
2032 | |
2113 | |
2033 | If the event loop is suspended for a long time, you can also force an |
2114 | If the event loop is suspended for a long time, you can also force an |
2034 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
2115 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
2035 | ()>. |
2116 | ()>, although that will push the event time of all outstanding events |
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2117 | further into the future. |
2036 | |
2118 | |
2037 | =head3 The special problem of unsynchronised clocks |
2119 | =head3 The special problem of unsynchronised clocks |
2038 | |
2120 | |
2039 | Modern systems have a variety of clocks - libev itself uses the normal |
2121 | Modern systems have a variety of clocks - libev itself uses the normal |
2040 | "wall clock" clock and, if available, the monotonic clock (to avoid time |
2122 | "wall clock" clock and, if available, the monotonic clock (to avoid time |
… | |
… | |
2103 | |
2185 | |
2104 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
2186 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
2105 | |
2187 | |
2106 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
2188 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
2107 | |
2189 | |
2108 | Configure the timer to trigger after C<after> seconds. If C<repeat> |
2190 | Configure the timer to trigger after C<after> seconds (fractional and |
2109 | is C<0.>, then it will automatically be stopped once the timeout is |
2191 | negative values are supported). If C<repeat> is C<0.>, then it will |
2110 | reached. If it is positive, then the timer will automatically be |
2192 | automatically be stopped once the timeout is reached. If it is positive, |
2111 | configured to trigger again C<repeat> seconds later, again, and again, |
2193 | then the timer will automatically be configured to trigger again C<repeat> |
2112 | until stopped manually. |
2194 | seconds later, again, and again, until stopped manually. |
2113 | |
2195 | |
2114 | The timer itself will do a best-effort at avoiding drift, that is, if |
2196 | The timer itself will do a best-effort at avoiding drift, that is, if |
2115 | you configure a timer to trigger every 10 seconds, then it will normally |
2197 | you configure a timer to trigger every 10 seconds, then it will normally |
2116 | trigger at exactly 10 second intervals. If, however, your program cannot |
2198 | trigger at exactly 10 second intervals. If, however, your program cannot |
2117 | keep up with the timer (because it takes longer than those 10 seconds to |
2199 | keep up with the timer (because it takes longer than those 10 seconds to |
… | |
… | |
2199 | Periodic watchers are also timers of a kind, but they are very versatile |
2281 | Periodic watchers are also timers of a kind, but they are very versatile |
2200 | (and unfortunately a bit complex). |
2282 | (and unfortunately a bit complex). |
2201 | |
2283 | |
2202 | Unlike C<ev_timer>, periodic watchers are not based on real time (or |
2284 | Unlike C<ev_timer>, periodic watchers are not based on real time (or |
2203 | relative time, the physical time that passes) but on wall clock time |
2285 | relative time, the physical time that passes) but on wall clock time |
2204 | (absolute time, the thing you can read on your calender or clock). The |
2286 | (absolute time, the thing you can read on your calendar or clock). The |
2205 | difference is that wall clock time can run faster or slower than real |
2287 | difference is that wall clock time can run faster or slower than real |
2206 | time, and time jumps are not uncommon (e.g. when you adjust your |
2288 | time, and time jumps are not uncommon (e.g. when you adjust your |
2207 | wrist-watch). |
2289 | wrist-watch). |
2208 | |
2290 | |
2209 | You can tell a periodic watcher to trigger after some specific point |
2291 | You can tell a periodic watcher to trigger after some specific point |
… | |
… | |
2214 | C<ev_timer>, which would still trigger roughly 10 seconds after starting |
2296 | C<ev_timer>, which would still trigger roughly 10 seconds after starting |
2215 | it, as it uses a relative timeout). |
2297 | it, as it uses a relative timeout). |
2216 | |
2298 | |
2217 | C<ev_periodic> watchers can also be used to implement vastly more complex |
2299 | C<ev_periodic> watchers can also be used to implement vastly more complex |
2218 | timers, such as triggering an event on each "midnight, local time", or |
2300 | timers, such as triggering an event on each "midnight, local time", or |
2219 | other complicated rules. This cannot be done with C<ev_timer> watchers, as |
2301 | other complicated rules. This cannot easily be done with C<ev_timer> |
2220 | those cannot react to time jumps. |
2302 | watchers, as those cannot react to time jumps. |
2221 | |
2303 | |
2222 | As with timers, the callback is guaranteed to be invoked only when the |
2304 | As with timers, the callback is guaranteed to be invoked only when the |
2223 | point in time where it is supposed to trigger has passed. If multiple |
2305 | point in time where it is supposed to trigger has passed. If multiple |
2224 | timers become ready during the same loop iteration then the ones with |
2306 | timers become ready during the same loop iteration then the ones with |
2225 | earlier time-out values are invoked before ones with later time-out values |
2307 | earlier time-out values are invoked before ones with later time-out values |
… | |
… | |
2311 | |
2393 | |
2312 | NOTE: I<< This callback must always return a time that is higher than or |
2394 | NOTE: I<< This callback must always return a time that is higher than or |
2313 | equal to the passed C<now> value >>. |
2395 | equal to the passed C<now> value >>. |
2314 | |
2396 | |
2315 | This can be used to create very complex timers, such as a timer that |
2397 | This can be used to create very complex timers, such as a timer that |
2316 | triggers on "next midnight, local time". To do this, you would calculate the |
2398 | triggers on "next midnight, local time". To do this, you would calculate |
2317 | next midnight after C<now> and return the timestamp value for this. How |
2399 | the next midnight after C<now> and return the timestamp value for |
2318 | you do this is, again, up to you (but it is not trivial, which is the main |
2400 | this. Here is a (completely untested, no error checking) example on how to |
2319 | reason I omitted it as an example). |
2401 | do this: |
|
|
2402 | |
|
|
2403 | #include <time.h> |
|
|
2404 | |
|
|
2405 | static ev_tstamp |
|
|
2406 | my_rescheduler (ev_periodic *w, ev_tstamp now) |
|
|
2407 | { |
|
|
2408 | time_t tnow = (time_t)now; |
|
|
2409 | struct tm tm; |
|
|
2410 | localtime_r (&tnow, &tm); |
|
|
2411 | |
|
|
2412 | tm.tm_sec = tm.tm_min = tm.tm_hour = 0; // midnight current day |
|
|
2413 | ++tm.tm_mday; // midnight next day |
|
|
2414 | |
|
|
2415 | return mktime (&tm); |
|
|
2416 | } |
|
|
2417 | |
|
|
2418 | Note: this code might run into trouble on days that have more then two |
|
|
2419 | midnights (beginning and end). |
2320 | |
2420 | |
2321 | =back |
2421 | =back |
2322 | |
2422 | |
2323 | =item ev_periodic_again (loop, ev_periodic *) |
2423 | =item ev_periodic_again (loop, ev_periodic *) |
2324 | |
2424 | |
… | |
… | |
2389 | |
2489 | |
2390 | ev_periodic hourly_tick; |
2490 | ev_periodic hourly_tick; |
2391 | ev_periodic_init (&hourly_tick, clock_cb, |
2491 | ev_periodic_init (&hourly_tick, clock_cb, |
2392 | fmod (ev_now (loop), 3600.), 3600., 0); |
2492 | fmod (ev_now (loop), 3600.), 3600., 0); |
2393 | ev_periodic_start (loop, &hourly_tick); |
2493 | ev_periodic_start (loop, &hourly_tick); |
2394 | |
2494 | |
2395 | |
2495 | |
2396 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
2496 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
2397 | |
2497 | |
2398 | Signal watchers will trigger an event when the process receives a specific |
2498 | Signal watchers will trigger an event when the process receives a specific |
2399 | signal one or more times. Even though signals are very asynchronous, libev |
2499 | signal one or more times. Even though signals are very asynchronous, libev |
… | |
… | |
2409 | only within the same loop, i.e. you can watch for C<SIGINT> in your |
2509 | only within the same loop, i.e. you can watch for C<SIGINT> in your |
2410 | default loop and for C<SIGIO> in another loop, but you cannot watch for |
2510 | default loop and for C<SIGIO> in another loop, but you cannot watch for |
2411 | C<SIGINT> in both the default loop and another loop at the same time. At |
2511 | C<SIGINT> in both the default loop and another loop at the same time. At |
2412 | the moment, C<SIGCHLD> is permanently tied to the default loop. |
2512 | the moment, C<SIGCHLD> is permanently tied to the default loop. |
2413 | |
2513 | |
2414 | When the first watcher gets started will libev actually register something |
2514 | Only after the first watcher for a signal is started will libev actually |
2415 | with the kernel (thus it coexists with your own signal handlers as long as |
2515 | register something with the kernel. It thus coexists with your own signal |
2416 | you don't register any with libev for the same signal). |
2516 | handlers as long as you don't register any with libev for the same signal. |
2417 | |
2517 | |
2418 | If possible and supported, libev will install its handlers with |
2518 | If possible and supported, libev will install its handlers with |
2419 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2519 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2420 | not be unduly interrupted. If you have a problem with system calls getting |
2520 | not be unduly interrupted. If you have a problem with system calls getting |
2421 | interrupted by signals you can block all signals in an C<ev_check> watcher |
2521 | interrupted by signals you can block all signals in an C<ev_check> watcher |
… | |
… | |
2606 | |
2706 | |
2607 | =head2 C<ev_stat> - did the file attributes just change? |
2707 | =head2 C<ev_stat> - did the file attributes just change? |
2608 | |
2708 | |
2609 | This watches a file system path for attribute changes. That is, it calls |
2709 | This watches a file system path for attribute changes. That is, it calls |
2610 | C<stat> on that path in regular intervals (or when the OS says it changed) |
2710 | C<stat> on that path in regular intervals (or when the OS says it changed) |
2611 | and sees if it changed compared to the last time, invoking the callback if |
2711 | and sees if it changed compared to the last time, invoking the callback |
2612 | it did. |
2712 | if it did. Starting the watcher C<stat>'s the file, so only changes that |
|
|
2713 | happen after the watcher has been started will be reported. |
2613 | |
2714 | |
2614 | The path does not need to exist: changing from "path exists" to "path does |
2715 | The path does not need to exist: changing from "path exists" to "path does |
2615 | not exist" is a status change like any other. The condition "path does not |
2716 | not exist" is a status change like any other. The condition "path does not |
2616 | exist" (or more correctly "path cannot be stat'ed") is signified by the |
2717 | exist" (or more correctly "path cannot be stat'ed") is signified by the |
2617 | C<st_nlink> field being zero (which is otherwise always forced to be at |
2718 | C<st_nlink> field being zero (which is otherwise always forced to be at |
… | |
… | |
2902 | |
3003 | |
2903 | Prepare and check watchers are often (but not always) used in pairs: |
3004 | Prepare and check watchers are often (but not always) used in pairs: |
2904 | prepare watchers get invoked before the process blocks and check watchers |
3005 | prepare watchers get invoked before the process blocks and check watchers |
2905 | afterwards. |
3006 | afterwards. |
2906 | |
3007 | |
2907 | You I<must not> call C<ev_run> or similar functions that enter |
3008 | You I<must not> call C<ev_run> (or similar functions that enter the |
2908 | the current event loop from either C<ev_prepare> or C<ev_check> |
3009 | current event loop) or C<ev_loop_fork> from either C<ev_prepare> or |
2909 | watchers. Other loops than the current one are fine, however. The |
3010 | C<ev_check> watchers. Other loops than the current one are fine, |
2910 | rationale behind this is that you do not need to check for recursion in |
3011 | however. The rationale behind this is that you do not need to check |
2911 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
3012 | for recursion in those watchers, i.e. the sequence will always be |
2912 | C<ev_check> so if you have one watcher of each kind they will always be |
3013 | C<ev_prepare>, blocking, C<ev_check> so if you have one watcher of each |
2913 | called in pairs bracketing the blocking call. |
3014 | kind they will always be called in pairs bracketing the blocking call. |
2914 | |
3015 | |
2915 | Their main purpose is to integrate other event mechanisms into libev and |
3016 | Their main purpose is to integrate other event mechanisms into libev and |
2916 | their use is somewhat advanced. They could be used, for example, to track |
3017 | their use is somewhat advanced. They could be used, for example, to track |
2917 | variable changes, implement your own watchers, integrate net-snmp or a |
3018 | variable changes, implement your own watchers, integrate net-snmp or a |
2918 | coroutine library and lots more. They are also occasionally useful if |
3019 | coroutine library and lots more. They are also occasionally useful if |
… | |
… | |
2962 | |
3063 | |
2963 | Using an C<ev_check> watcher is almost enough: it will be called on the |
3064 | Using an C<ev_check> watcher is almost enough: it will be called on the |
2964 | next event loop iteration. However, that isn't as soon as possible - |
3065 | next event loop iteration. However, that isn't as soon as possible - |
2965 | without external events, your C<ev_check> watcher will not be invoked. |
3066 | without external events, your C<ev_check> watcher will not be invoked. |
2966 | |
3067 | |
2967 | |
|
|
2968 | This is where C<ev_idle> watchers come in handy - all you need is a |
3068 | This is where C<ev_idle> watchers come in handy - all you need is a |
2969 | single global idle watcher that is active as long as you have one active |
3069 | single global idle watcher that is active as long as you have one active |
2970 | C<ev_check> watcher. The C<ev_idle> watcher makes sure the event loop |
3070 | C<ev_check> watcher. The C<ev_idle> watcher makes sure the event loop |
2971 | will not sleep, and the C<ev_check> watcher makes sure a callback gets |
3071 | will not sleep, and the C<ev_check> watcher makes sure a callback gets |
2972 | invoked. Neither watcher alone can do that. |
3072 | invoked. Neither watcher alone can do that. |
… | |
… | |
3178 | |
3278 | |
3179 | =over 4 |
3279 | =over 4 |
3180 | |
3280 | |
3181 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
3281 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
3182 | |
3282 | |
3183 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
3283 | =item ev_embed_set (ev_embed *, struct ev_loop *embedded_loop) |
3184 | |
3284 | |
3185 | Configures the watcher to embed the given loop, which must be |
3285 | Configures the watcher to embed the given loop, which must be |
3186 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
3286 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
3187 | invoked automatically, otherwise it is the responsibility of the callback |
3287 | invoked automatically, otherwise it is the responsibility of the callback |
3188 | to invoke it (it will continue to be called until the sweep has been done, |
3288 | to invoke it (it will continue to be called until the sweep has been done, |
… | |
… | |
3209 | used). |
3309 | used). |
3210 | |
3310 | |
3211 | struct ev_loop *loop_hi = ev_default_init (0); |
3311 | struct ev_loop *loop_hi = ev_default_init (0); |
3212 | struct ev_loop *loop_lo = 0; |
3312 | struct ev_loop *loop_lo = 0; |
3213 | ev_embed embed; |
3313 | ev_embed embed; |
3214 | |
3314 | |
3215 | // see if there is a chance of getting one that works |
3315 | // see if there is a chance of getting one that works |
3216 | // (remember that a flags value of 0 means autodetection) |
3316 | // (remember that a flags value of 0 means autodetection) |
3217 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3317 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3218 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3318 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3219 | : 0; |
3319 | : 0; |
… | |
… | |
3233 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
3333 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
3234 | |
3334 | |
3235 | struct ev_loop *loop = ev_default_init (0); |
3335 | struct ev_loop *loop = ev_default_init (0); |
3236 | struct ev_loop *loop_socket = 0; |
3336 | struct ev_loop *loop_socket = 0; |
3237 | ev_embed embed; |
3337 | ev_embed embed; |
3238 | |
3338 | |
3239 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3339 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3240 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3340 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3241 | { |
3341 | { |
3242 | ev_embed_init (&embed, 0, loop_socket); |
3342 | ev_embed_init (&embed, 0, loop_socket); |
3243 | ev_embed_start (loop, &embed); |
3343 | ev_embed_start (loop, &embed); |
… | |
… | |
3251 | |
3351 | |
3252 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
3352 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
3253 | |
3353 | |
3254 | Fork watchers are called when a C<fork ()> was detected (usually because |
3354 | Fork watchers are called when a C<fork ()> was detected (usually because |
3255 | whoever is a good citizen cared to tell libev about it by calling |
3355 | whoever is a good citizen cared to tell libev about it by calling |
3256 | C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the |
3356 | C<ev_loop_fork>). The invocation is done before the event loop blocks next |
3257 | event loop blocks next and before C<ev_check> watchers are being called, |
3357 | and before C<ev_check> watchers are being called, and only in the child |
3258 | and only in the child after the fork. If whoever good citizen calling |
3358 | after the fork. If whoever good citizen calling C<ev_default_fork> cheats |
3259 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
3359 | and calls it in the wrong process, the fork handlers will be invoked, too, |
3260 | handlers will be invoked, too, of course. |
3360 | of course. |
3261 | |
3361 | |
3262 | =head3 The special problem of life after fork - how is it possible? |
3362 | =head3 The special problem of life after fork - how is it possible? |
3263 | |
3363 | |
3264 | Most uses of C<fork()> consist of forking, then some simple calls to set |
3364 | Most uses of C<fork ()> consist of forking, then some simple calls to set |
3265 | up/change the process environment, followed by a call to C<exec()>. This |
3365 | up/change the process environment, followed by a call to C<exec()>. This |
3266 | sequence should be handled by libev without any problems. |
3366 | sequence should be handled by libev without any problems. |
3267 | |
3367 | |
3268 | This changes when the application actually wants to do event handling |
3368 | This changes when the application actually wants to do event handling |
3269 | in the child, or both parent in child, in effect "continuing" after the |
3369 | in the child, or both parent in child, in effect "continuing" after the |
… | |
… | |
3507 | |
3607 | |
3508 | There are some other functions of possible interest. Described. Here. Now. |
3608 | There are some other functions of possible interest. Described. Here. Now. |
3509 | |
3609 | |
3510 | =over 4 |
3610 | =over 4 |
3511 | |
3611 | |
3512 | =item ev_once (loop, int fd, int events, ev_tstamp timeout, callback) |
3612 | =item ev_once (loop, int fd, int events, ev_tstamp timeout, callback, arg) |
3513 | |
3613 | |
3514 | This function combines a simple timer and an I/O watcher, calls your |
3614 | This function combines a simple timer and an I/O watcher, calls your |
3515 | callback on whichever event happens first and automatically stops both |
3615 | callback on whichever event happens first and automatically stops both |
3516 | watchers. This is useful if you want to wait for a single event on an fd |
3616 | watchers. This is useful if you want to wait for a single event on an fd |
3517 | or timeout without having to allocate/configure/start/stop/free one or |
3617 | or timeout without having to allocate/configure/start/stop/free one or |
… | |
… | |
3659 | already been invoked. |
3759 | already been invoked. |
3660 | |
3760 | |
3661 | A common way around all these issues is to make sure that |
3761 | A common way around all these issues is to make sure that |
3662 | C<start_new_request> I<always> returns before the callback is invoked. If |
3762 | C<start_new_request> I<always> returns before the callback is invoked. If |
3663 | C<start_new_request> immediately knows the result, it can artificially |
3763 | C<start_new_request> immediately knows the result, it can artificially |
3664 | delay invoking the callback by e.g. using a C<prepare> or C<idle> watcher |
3764 | delay invoking the callback by using a C<prepare> or C<idle> watcher for |
3665 | for example, or more sneakily, by reusing an existing (stopped) watcher |
3765 | example, or more sneakily, by reusing an existing (stopped) watcher and |
3666 | and pushing it into the pending queue: |
3766 | pushing it into the pending queue: |
3667 | |
3767 | |
3668 | ev_set_cb (watcher, callback); |
3768 | ev_set_cb (watcher, callback); |
3669 | ev_feed_event (EV_A_ watcher, 0); |
3769 | ev_feed_event (EV_A_ watcher, 0); |
3670 | |
3770 | |
3671 | This way, C<start_new_request> can safely return before the callback is |
3771 | This way, C<start_new_request> can safely return before the callback is |
… | |
… | |
3679 | |
3779 | |
3680 | This brings the problem of exiting - a callback might want to finish the |
3780 | This brings the problem of exiting - a callback might want to finish the |
3681 | main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but |
3781 | main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but |
3682 | a modal "Are you sure?" dialog is still waiting), or just the nested one |
3782 | a modal "Are you sure?" dialog is still waiting), or just the nested one |
3683 | and not the main one (e.g. user clocked "Ok" in a modal dialog), or some |
3783 | and not the main one (e.g. user clocked "Ok" in a modal dialog), or some |
3684 | other combination: In these cases, C<ev_break> will not work alone. |
3784 | other combination: In these cases, a simple C<ev_break> will not work. |
3685 | |
3785 | |
3686 | The solution is to maintain "break this loop" variable for each C<ev_run> |
3786 | The solution is to maintain "break this loop" variable for each C<ev_run> |
3687 | invocation, and use a loop around C<ev_run> until the condition is |
3787 | invocation, and use a loop around C<ev_run> until the condition is |
3688 | triggered, using C<EVRUN_ONCE>: |
3788 | triggered, using C<EVRUN_ONCE>: |
3689 | |
3789 | |
… | |
… | |
3893 | To embed libev, see L</EMBEDDING>, but in short, it's easiest to create two |
3993 | To embed libev, see L</EMBEDDING>, but in short, it's easiest to create two |
3894 | files, F<my_ev.h> and F<my_ev.c> that include the respective libev files: |
3994 | files, F<my_ev.h> and F<my_ev.c> that include the respective libev files: |
3895 | |
3995 | |
3896 | // my_ev.h |
3996 | // my_ev.h |
3897 | #define EV_CB_DECLARE(type) struct my_coro *cb; |
3997 | #define EV_CB_DECLARE(type) struct my_coro *cb; |
3898 | #define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb); |
3998 | #define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb) |
3899 | #include "../libev/ev.h" |
3999 | #include "../libev/ev.h" |
3900 | |
4000 | |
3901 | // my_ev.c |
4001 | // my_ev.c |
3902 | #define EV_H "my_ev.h" |
4002 | #define EV_H "my_ev.h" |
3903 | #include "../libev/ev.c" |
4003 | #include "../libev/ev.c" |
… | |
… | |
3949 | The normal C API should work fine when used from C++: both ev.h and the |
4049 | The normal C API should work fine when used from C++: both ev.h and the |
3950 | libev sources can be compiled as C++. Therefore, code that uses the C API |
4050 | libev sources can be compiled as C++. Therefore, code that uses the C API |
3951 | will work fine. |
4051 | will work fine. |
3952 | |
4052 | |
3953 | Proper exception specifications might have to be added to callbacks passed |
4053 | Proper exception specifications might have to be added to callbacks passed |
3954 | to libev: exceptions may be thrown only from watcher callbacks, all |
4054 | to libev: exceptions may be thrown only from watcher callbacks, all other |
3955 | other callbacks (allocator, syserr, loop acquire/release and periodioc |
4055 | callbacks (allocator, syserr, loop acquire/release and periodic reschedule |
3956 | reschedule callbacks) must not throw exceptions, and might need a C<throw |
4056 | callbacks) must not throw exceptions, and might need a C<noexcept> |
3957 | ()> specification. If you have code that needs to be compiled as both C |
4057 | specification. If you have code that needs to be compiled as both C and |
3958 | and C++ you can use the C<EV_THROW> macro for this: |
4058 | C++ you can use the C<EV_NOEXCEPT> macro for this: |
3959 | |
4059 | |
3960 | static void |
4060 | static void |
3961 | fatal_error (const char *msg) EV_THROW |
4061 | fatal_error (const char *msg) EV_NOEXCEPT |
3962 | { |
4062 | { |
3963 | perror (msg); |
4063 | perror (msg); |
3964 | abort (); |
4064 | abort (); |
3965 | } |
4065 | } |
3966 | |
4066 | |
… | |
… | |
3980 | Libev comes with some simplistic wrapper classes for C++ that mainly allow |
4080 | Libev comes with some simplistic wrapper classes for C++ that mainly allow |
3981 | you to use some convenience methods to start/stop watchers and also change |
4081 | you to use some convenience methods to start/stop watchers and also change |
3982 | the callback model to a model using method callbacks on objects. |
4082 | the callback model to a model using method callbacks on objects. |
3983 | |
4083 | |
3984 | To use it, |
4084 | To use it, |
3985 | |
4085 | |
3986 | #include <ev++.h> |
4086 | #include <ev++.h> |
3987 | |
4087 | |
3988 | This automatically includes F<ev.h> and puts all of its definitions (many |
4088 | This automatically includes F<ev.h> and puts all of its definitions (many |
3989 | of them macros) into the global namespace. All C++ specific things are |
4089 | of them macros) into the global namespace. All C++ specific things are |
3990 | put into the C<ev> namespace. It should support all the same embedding |
4090 | put into the C<ev> namespace. It should support all the same embedding |
… | |
… | |
4093 | void operator() (ev::io &w, int revents) |
4193 | void operator() (ev::io &w, int revents) |
4094 | { |
4194 | { |
4095 | ... |
4195 | ... |
4096 | } |
4196 | } |
4097 | } |
4197 | } |
4098 | |
4198 | |
4099 | myfunctor f; |
4199 | myfunctor f; |
4100 | |
4200 | |
4101 | ev::io w; |
4201 | ev::io w; |
4102 | w.set (&f); |
4202 | w.set (&f); |
4103 | |
4203 | |
… | |
… | |
4121 | Associates a different C<struct ev_loop> with this watcher. You can only |
4221 | Associates a different C<struct ev_loop> with this watcher. You can only |
4122 | do this when the watcher is inactive (and not pending either). |
4222 | do this when the watcher is inactive (and not pending either). |
4123 | |
4223 | |
4124 | =item w->set ([arguments]) |
4224 | =item w->set ([arguments]) |
4125 | |
4225 | |
4126 | Basically the same as C<ev_TYPE_set>, with the same arguments. Either this |
4226 | Basically the same as C<ev_TYPE_set> (except for C<ev::embed> watchers>), |
4127 | method or a suitable start method must be called at least once. Unlike the |
4227 | with the same arguments. Either this method or a suitable start method |
4128 | C counterpart, an active watcher gets automatically stopped and restarted |
4228 | must be called at least once. Unlike the C counterpart, an active watcher |
4129 | when reconfiguring it with this method. |
4229 | gets automatically stopped and restarted when reconfiguring it with this |
|
|
4230 | method. |
|
|
4231 | |
|
|
4232 | For C<ev::embed> watchers this method is called C<set_embed>, to avoid |
|
|
4233 | clashing with the C<set (loop)> method. |
4130 | |
4234 | |
4131 | =item w->start () |
4235 | =item w->start () |
4132 | |
4236 | |
4133 | Starts the watcher. Note that there is no C<loop> argument, as the |
4237 | Starts the watcher. Note that there is no C<loop> argument, as the |
4134 | constructor already stores the event loop. |
4238 | constructor already stores the event loop. |
… | |
… | |
4238 | |
4342 | |
4239 | Brian Maher has written a partial interface to libev for lua (at the |
4343 | Brian Maher has written a partial interface to libev for lua (at the |
4240 | time of this writing, only C<ev_io> and C<ev_timer>), to be found at |
4344 | time of this writing, only C<ev_io> and C<ev_timer>), to be found at |
4241 | L<http://github.com/brimworks/lua-ev>. |
4345 | L<http://github.com/brimworks/lua-ev>. |
4242 | |
4346 | |
|
|
4347 | =item Javascript |
|
|
4348 | |
|
|
4349 | Node.js (L<http://nodejs.org>) uses libev as the underlying event library. |
|
|
4350 | |
|
|
4351 | =item Others |
|
|
4352 | |
|
|
4353 | There are others, and I stopped counting. |
|
|
4354 | |
4243 | =back |
4355 | =back |
4244 | |
4356 | |
4245 | |
4357 | |
4246 | =head1 MACRO MAGIC |
4358 | =head1 MACRO MAGIC |
4247 | |
4359 | |
… | |
… | |
4364 | ev_vars.h |
4476 | ev_vars.h |
4365 | ev_wrap.h |
4477 | ev_wrap.h |
4366 | |
4478 | |
4367 | ev_win32.c required on win32 platforms only |
4479 | ev_win32.c required on win32 platforms only |
4368 | |
4480 | |
4369 | ev_select.c only when select backend is enabled (which is enabled by default) |
4481 | ev_select.c only when select backend is enabled |
4370 | ev_poll.c only when poll backend is enabled (disabled by default) |
4482 | ev_poll.c only when poll backend is enabled |
4371 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
4483 | ev_epoll.c only when the epoll backend is enabled |
|
|
4484 | ev_linuxaio.c only when the linux aio backend is enabled |
4372 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
4485 | ev_kqueue.c only when the kqueue backend is enabled |
4373 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
4486 | ev_port.c only when the solaris port backend is enabled |
4374 | |
4487 | |
4375 | F<ev.c> includes the backend files directly when enabled, so you only need |
4488 | F<ev.c> includes the backend files directly when enabled, so you only need |
4376 | to compile this single file. |
4489 | to compile this single file. |
4377 | |
4490 | |
4378 | =head3 LIBEVENT COMPATIBILITY API |
4491 | =head3 LIBEVENT COMPATIBILITY API |
… | |
… | |
4546 | If programs implement their own fd to handle mapping on win32, then this |
4659 | If programs implement their own fd to handle mapping on win32, then this |
4547 | macro can be used to override the C<close> function, useful to unregister |
4660 | macro can be used to override the C<close> function, useful to unregister |
4548 | file descriptors again. Note that the replacement function has to close |
4661 | file descriptors again. Note that the replacement function has to close |
4549 | the underlying OS handle. |
4662 | the underlying OS handle. |
4550 | |
4663 | |
|
|
4664 | =item EV_USE_WSASOCKET |
|
|
4665 | |
|
|
4666 | If defined to be C<1>, libev will use C<WSASocket> to create its internal |
|
|
4667 | communication socket, which works better in some environments. Otherwise, |
|
|
4668 | the normal C<socket> function will be used, which works better in other |
|
|
4669 | environments. |
|
|
4670 | |
4551 | =item EV_USE_POLL |
4671 | =item EV_USE_POLL |
4552 | |
4672 | |
4553 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
4673 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
4554 | backend. Otherwise it will be enabled on non-win32 platforms. It |
4674 | backend. Otherwise it will be enabled on non-win32 platforms. It |
4555 | takes precedence over select. |
4675 | takes precedence over select. |
… | |
… | |
4559 | If defined to be C<1>, libev will compile in support for the Linux |
4679 | If defined to be C<1>, libev will compile in support for the Linux |
4560 | C<epoll>(7) backend. Its availability will be detected at runtime, |
4680 | C<epoll>(7) backend. Its availability will be detected at runtime, |
4561 | otherwise another method will be used as fallback. This is the preferred |
4681 | otherwise another method will be used as fallback. This is the preferred |
4562 | backend for GNU/Linux systems. If undefined, it will be enabled if the |
4682 | backend for GNU/Linux systems. If undefined, it will be enabled if the |
4563 | headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
4683 | headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
|
|
4684 | |
|
|
4685 | =item EV_USE_LINUXAIO |
|
|
4686 | |
|
|
4687 | If defined to be C<1>, libev will compile in support for the Linux |
|
|
4688 | aio backend. Due to it's currenbt limitations it has to be requested |
|
|
4689 | explicitly. If undefined, it will be enabled on linux, otherwise |
|
|
4690 | disabled. |
4564 | |
4691 | |
4565 | =item EV_USE_KQUEUE |
4692 | =item EV_USE_KQUEUE |
4566 | |
4693 | |
4567 | If defined to be C<1>, libev will compile in support for the BSD style |
4694 | If defined to be C<1>, libev will compile in support for the BSD style |
4568 | C<kqueue>(2) backend. Its actual availability will be detected at runtime, |
4695 | C<kqueue>(2) backend. Its actual availability will be detected at runtime, |
… | |
… | |
4599 | different cpus (or different cpu cores). This reduces dependencies |
4726 | different cpus (or different cpu cores). This reduces dependencies |
4600 | and makes libev faster. |
4727 | and makes libev faster. |
4601 | |
4728 | |
4602 | =item EV_NO_THREADS |
4729 | =item EV_NO_THREADS |
4603 | |
4730 | |
4604 | If defined to be C<1>, libev will assume that it will never be called |
4731 | If defined to be C<1>, libev will assume that it will never be called from |
4605 | from different threads, which is a stronger assumption than C<EV_NO_SMP>, |
4732 | different threads (that includes signal handlers), which is a stronger |
4606 | above. This reduces dependencies and makes libev faster. |
4733 | assumption than C<EV_NO_SMP>, above. This reduces dependencies and makes |
|
|
4734 | libev faster. |
4607 | |
4735 | |
4608 | =item EV_ATOMIC_T |
4736 | =item EV_ATOMIC_T |
4609 | |
4737 | |
4610 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
4738 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
4611 | access is atomic and serialised with respect to other threads or signal |
4739 | access is atomic with respect to other threads or signal contexts. No |
4612 | contexts. No such type is easily found in the C language, so you can |
4740 | such type is easily found in the C language, so you can provide your own |
4613 | provide your own type that you know is safe for your purposes. It is used |
4741 | type that you know is safe for your purposes. It is used both for signal |
4614 | both for signal handler "locking" as well as for signal and thread safety |
4742 | handler "locking" as well as for signal and thread safety in C<ev_async> |
4615 | in C<ev_async> watchers. |
4743 | watchers. |
4616 | |
4744 | |
4617 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
4745 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
4618 | (from F<signal.h>), which is usually good enough on most platforms, |
4746 | (from F<signal.h>), which is usually good enough on most platforms. |
4619 | although strictly speaking using a type that also implies a memory fence |
|
|
4620 | is required. |
|
|
4621 | |
4747 | |
4622 | =item EV_H (h) |
4748 | =item EV_H (h) |
4623 | |
4749 | |
4624 | The name of the F<ev.h> header file used to include it. The default if |
4750 | The name of the F<ev.h> header file used to include it. The default if |
4625 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
4751 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
… | |
… | |
5272 | structure (guaranteed by POSIX but not by ISO C for example), but it also |
5398 | structure (guaranteed by POSIX but not by ISO C for example), but it also |
5273 | assumes that the same (machine) code can be used to call any watcher |
5399 | assumes that the same (machine) code can be used to call any watcher |
5274 | callback: The watcher callbacks have different type signatures, but libev |
5400 | callback: The watcher callbacks have different type signatures, but libev |
5275 | calls them using an C<ev_watcher *> internally. |
5401 | calls them using an C<ev_watcher *> internally. |
5276 | |
5402 | |
|
|
5403 | =item null pointers and integer zero are represented by 0 bytes |
|
|
5404 | |
|
|
5405 | Libev uses C<memset> to initialise structs and arrays to C<0> bytes, and |
|
|
5406 | relies on this setting pointers and integers to null. |
|
|
5407 | |
5277 | =item pointer accesses must be thread-atomic |
5408 | =item pointer accesses must be thread-atomic |
5278 | |
5409 | |
5279 | Accessing a pointer value must be atomic, it must both be readable and |
5410 | Accessing a pointer value must be atomic, it must both be readable and |
5280 | writable in one piece - this is the case on all current architectures. |
5411 | writable in one piece - this is the case on all current architectures. |
5281 | |
5412 | |
… | |
… | |
5294 | thread" or will block signals process-wide, both behaviours would |
5425 | thread" or will block signals process-wide, both behaviours would |
5295 | be compatible with libev. Interaction between C<sigprocmask> and |
5426 | be compatible with libev. Interaction between C<sigprocmask> and |
5296 | C<pthread_sigmask> could complicate things, however. |
5427 | C<pthread_sigmask> could complicate things, however. |
5297 | |
5428 | |
5298 | The most portable way to handle signals is to block signals in all threads |
5429 | The most portable way to handle signals is to block signals in all threads |
5299 | except the initial one, and run the default loop in the initial thread as |
5430 | except the initial one, and run the signal handling loop in the initial |
5300 | well. |
5431 | thread as well. |
5301 | |
5432 | |
5302 | =item C<long> must be large enough for common memory allocation sizes |
5433 | =item C<long> must be large enough for common memory allocation sizes |
5303 | |
5434 | |
5304 | To improve portability and simplify its API, libev uses C<long> internally |
5435 | To improve portability and simplify its API, libev uses C<long> internally |
5305 | instead of C<size_t> when allocating its data structures. On non-POSIX |
5436 | instead of C<size_t> when allocating its data structures. On non-POSIX |
… | |
… | |
5409 | =over 4 |
5540 | =over 4 |
5410 | |
5541 | |
5411 | =item C<EV_COMPAT3> backwards compatibility mechanism |
5542 | =item C<EV_COMPAT3> backwards compatibility mechanism |
5412 | |
5543 | |
5413 | The backward compatibility mechanism can be controlled by |
5544 | The backward compatibility mechanism can be controlled by |
5414 | C<EV_COMPAT3>. See L</PREPROCESSOR SYMBOLS/MACROS> in the L</EMBEDDING> |
5545 | C<EV_COMPAT3>. See L</"PREPROCESSOR SYMBOLS/MACROS"> in the L</EMBEDDING> |
5415 | section. |
5546 | section. |
5416 | |
5547 | |
5417 | =item C<ev_default_destroy> and C<ev_default_fork> have been removed |
5548 | =item C<ev_default_destroy> and C<ev_default_fork> have been removed |
5418 | |
5549 | |
5419 | These calls can be replaced easily by their C<ev_loop_xxx> counterparts: |
5550 | These calls can be replaced easily by their C<ev_loop_xxx> counterparts: |