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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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82 | |
84 | |
83 | =head1 WHAT TO READ WHEN IN A HURRY |
85 | =head1 WHAT TO READ WHEN IN A HURRY |
84 | |
86 | |
85 | This manual tries to be very detailed, but unfortunately, this also makes |
87 | This manual tries to be very detailed, but unfortunately, this also makes |
86 | it very long. If you just want to know the basics of libev, I suggest |
88 | it very long. If you just want to know the basics of libev, I suggest |
87 | reading L<ANATOMY OF A WATCHER>, then the L<EXAMPLE PROGRAM> above and |
89 | reading L</ANATOMY OF A WATCHER>, then the L</EXAMPLE PROGRAM> above and |
88 | look up the missing functions in L<GLOBAL FUNCTIONS> and the C<ev_io> and |
90 | look up the missing functions in L</GLOBAL FUNCTIONS> and the C<ev_io> and |
89 | C<ev_timer> sections in L<WATCHER TYPES>. |
91 | C<ev_timer> sections in L</WATCHER TYPES>. |
90 | |
92 | |
91 | =head1 ABOUT LIBEV |
93 | =head1 ABOUT LIBEV |
92 | |
94 | |
93 | Libev is an event loop: you register interest in certain events (such as a |
95 | Libev is an event loop: you register interest in certain events (such as a |
94 | file descriptor being readable or a timeout occurring), and it will manage |
96 | file descriptor being readable or a timeout occurring), and it will manage |
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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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247 | the current system, you would need to look at C<ev_embeddable_backends () |
249 | the current system, you would need to look at C<ev_embeddable_backends () |
248 | & ev_supported_backends ()>, likewise for recommended ones. |
250 | & ev_supported_backends ()>, likewise for recommended ones. |
249 | |
251 | |
250 | See the description of C<ev_embed> watchers for more info. |
252 | See the description of C<ev_embed> watchers for more info. |
251 | |
253 | |
252 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
254 | =item ev_set_allocator (void *(*cb)(void *ptr, long size) throw ()) |
253 | |
255 | |
254 | Sets the allocation function to use (the prototype is similar - the |
256 | Sets the allocation function to use (the prototype is similar - the |
255 | semantics are identical to the C<realloc> C89/SuS/POSIX function). It is |
257 | semantics are identical to the C<realloc> C89/SuS/POSIX function). It is |
256 | used to allocate and free memory (no surprises here). If it returns zero |
258 | used to allocate and free memory (no surprises here). If it returns zero |
257 | when memory needs to be allocated (C<size != 0>), the library might abort |
259 | when memory needs to be allocated (C<size != 0>), the library might abort |
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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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283 | } |
305 | } |
284 | |
306 | |
285 | ... |
307 | ... |
286 | ev_set_allocator (persistent_realloc); |
308 | ev_set_allocator (persistent_realloc); |
287 | |
309 | |
288 | =item ev_set_syserr_cb (void (*cb)(const char *msg)) |
310 | =item ev_set_syserr_cb (void (*cb)(const char *msg) throw ()) |
289 | |
311 | |
290 | Set the callback function to call on a retryable system call error (such |
312 | Set the callback function to call on a retryable system call error (such |
291 | as failed select, poll, epoll_wait). The message is a printable string |
313 | as failed select, poll, epoll_wait). The message is a printable string |
292 | indicating the system call or subsystem causing the problem. If this |
314 | indicating the system call or subsystem causing the problem. If this |
293 | callback is set, then libev will expect it to remedy the situation, no |
315 | callback is set, then libev will expect it to remedy the situation, no |
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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. |
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573 | |
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574 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
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575 | C<EVBACKEND_POLL>. |
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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. |
548 | |
617 | |
549 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
618 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
550 | C<EVBACKEND_POLL>. |
619 | C<EVBACKEND_POLL>. |
551 | |
620 | |
552 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
621 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
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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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764 | |
843 | |
765 | This function is rarely useful, but when some event callback runs for a |
844 | This function is rarely useful, but when some event callback runs for a |
766 | very long time without entering the event loop, updating libev's idea of |
845 | very long time without entering the event loop, updating libev's idea of |
767 | the current time is a good idea. |
846 | the current time is a good idea. |
768 | |
847 | |
769 | See also L<The special problem of time updates> in the C<ev_timer> section. |
848 | See also L</The special problem of time updates> in the C<ev_timer> section. |
770 | |
849 | |
771 | =item ev_suspend (loop) |
850 | =item ev_suspend (loop) |
772 | |
851 | |
773 | =item ev_resume (loop) |
852 | =item ev_resume (loop) |
774 | |
853 | |
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1016 | invoke the actual watchers inside another context (another thread etc.). |
1095 | invoke the actual watchers inside another context (another thread etc.). |
1017 | |
1096 | |
1018 | If you want to reset the callback, use C<ev_invoke_pending> as new |
1097 | If you want to reset the callback, use C<ev_invoke_pending> as new |
1019 | callback. |
1098 | callback. |
1020 | |
1099 | |
1021 | =item ev_set_loop_release_cb (loop, void (*release)(EV_P), void (*acquire)(EV_P)) |
1100 | =item ev_set_loop_release_cb (loop, void (*release)(EV_P) throw (), void (*acquire)(EV_P) throw ()) |
1022 | |
1101 | |
1023 | Sometimes you want to share the same loop between multiple threads. This |
1102 | Sometimes you want to share the same loop between multiple threads. This |
1024 | can be done relatively simply by putting mutex_lock/unlock calls around |
1103 | can be done relatively simply by putting mutex_lock/unlock calls around |
1025 | each call to a libev function. |
1104 | each call to a libev function. |
1026 | |
1105 | |
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1174 | |
1253 | |
1175 | =item C<EV_PREPARE> |
1254 | =item C<EV_PREPARE> |
1176 | |
1255 | |
1177 | =item C<EV_CHECK> |
1256 | =item C<EV_CHECK> |
1178 | |
1257 | |
1179 | All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts |
1258 | All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts to |
1180 | to gather new events, and all C<ev_check> watchers are invoked just after |
1259 | gather new events, and all C<ev_check> watchers are queued (not invoked) |
1181 | C<ev_run> has gathered them, but before it invokes any callbacks for any |
1260 | just after C<ev_run> has gathered them, but before it queues any callbacks |
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1261 | for any received events. That means C<ev_prepare> watchers are the last |
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1262 | watchers invoked before the event loop sleeps or polls for new events, and |
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1263 | C<ev_check> watchers will be invoked before any other watchers of the same |
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1264 | or lower priority within an event loop iteration. |
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1265 | |
1182 | received events. Callbacks of both watcher types can start and stop as |
1266 | Callbacks of both watcher types can start and stop as many watchers as |
1183 | many watchers as they want, and all of them will be taken into account |
1267 | they want, and all of them will be taken into account (for example, a |
1184 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
1268 | C<ev_prepare> watcher might start an idle watcher to keep C<ev_run> from |
1185 | C<ev_run> from blocking). |
1269 | blocking). |
1186 | |
1270 | |
1187 | =item C<EV_EMBED> |
1271 | =item C<EV_EMBED> |
1188 | |
1272 | |
1189 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1273 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1190 | |
1274 | |
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1313 | |
1397 | |
1314 | =item callback ev_cb (ev_TYPE *watcher) |
1398 | =item callback ev_cb (ev_TYPE *watcher) |
1315 | |
1399 | |
1316 | Returns the callback currently set on the watcher. |
1400 | Returns the callback currently set on the watcher. |
1317 | |
1401 | |
1318 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1402 | =item ev_set_cb (ev_TYPE *watcher, callback) |
1319 | |
1403 | |
1320 | Change the callback. You can change the callback at virtually any time |
1404 | Change the callback. You can change the callback at virtually any time |
1321 | (modulo threads). |
1405 | (modulo threads). |
1322 | |
1406 | |
1323 | =item ev_set_priority (ev_TYPE *watcher, int priority) |
1407 | =item ev_set_priority (ev_TYPE *watcher, int priority) |
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1341 | or might not have been clamped to the valid range. |
1425 | or might not have been clamped to the valid range. |
1342 | |
1426 | |
1343 | The default priority used by watchers when no priority has been set is |
1427 | The default priority used by watchers when no priority has been set is |
1344 | always C<0>, which is supposed to not be too high and not be too low :). |
1428 | always C<0>, which is supposed to not be too high and not be too low :). |
1345 | |
1429 | |
1346 | See L<WATCHER PRIORITY MODELS>, below, for a more thorough treatment of |
1430 | See L</WATCHER PRIORITY MODELS>, below, for a more thorough treatment of |
1347 | priorities. |
1431 | priorities. |
1348 | |
1432 | |
1349 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
1433 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
1350 | |
1434 | |
1351 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
1435 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
… | |
… | |
1376 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
1460 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
1377 | functions that do not need a watcher. |
1461 | functions that do not need a watcher. |
1378 | |
1462 | |
1379 | =back |
1463 | =back |
1380 | |
1464 | |
1381 | See also the L<ASSOCIATING CUSTOM DATA WITH A WATCHER> and L<BUILDING YOUR |
1465 | See also the L</ASSOCIATING CUSTOM DATA WITH A WATCHER> and L</BUILDING YOUR |
1382 | OWN COMPOSITE WATCHERS> idioms. |
1466 | OWN COMPOSITE WATCHERS> idioms. |
1383 | |
1467 | |
1384 | =head2 WATCHER STATES |
1468 | =head2 WATCHER STATES |
1385 | |
1469 | |
1386 | There are various watcher states mentioned throughout this manual - |
1470 | There are various watcher states mentioned throughout this manual - |
… | |
… | |
1388 | 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 |
1389 | rules might look complicated, they usually do "the right thing". |
1473 | rules might look complicated, they usually do "the right thing". |
1390 | |
1474 | |
1391 | =over 4 |
1475 | =over 4 |
1392 | |
1476 | |
1393 | =item initialiased |
1477 | =item initialised |
1394 | |
1478 | |
1395 | 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 |
1396 | 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 |
1397 | 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. |
1398 | |
1482 | |
… | |
… | |
1596 | |
1680 | |
1597 | But really, best use non-blocking mode. |
1681 | But really, best use non-blocking mode. |
1598 | |
1682 | |
1599 | =head3 The special problem of disappearing file descriptors |
1683 | =head3 The special problem of disappearing file descriptors |
1600 | |
1684 | |
1601 | 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 |
1602 | 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 |
1603 | 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 |
1604 | 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 |
1605 | 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 |
1606 | 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, |
1607 | fact, a different file descriptor. |
1691 | in fact, a different file descriptor. |
1608 | |
1692 | |
1609 | 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 |
1610 | 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 |
1611 | will assume that this is potentially a new file descriptor, otherwise |
1695 | will assume that this is potentially a new file descriptor, otherwise |
1612 | 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 |
… | |
… | |
1661 | 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 |
1662 | reuse the same code path. |
1746 | reuse the same code path. |
1663 | |
1747 | |
1664 | =head3 The special problem of fork |
1748 | =head3 The special problem of fork |
1665 | |
1749 | |
1666 | 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 ()> |
1667 | 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 |
1668 | 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 |
|
|
1753 | child. |
1669 | |
1754 | |
1670 | 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 |
1671 | ()> 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 |
1672 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
1757 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
1673 | |
1758 | |
… | |
… | |
1874 | callback (EV_P_ ev_timer *w, int revents) |
1959 | callback (EV_P_ ev_timer *w, int revents) |
1875 | { |
1960 | { |
1876 | // calculate when the timeout would happen |
1961 | // calculate when the timeout would happen |
1877 | ev_tstamp after = last_activity - ev_now (EV_A) + timeout; |
1962 | ev_tstamp after = last_activity - ev_now (EV_A) + timeout; |
1878 | |
1963 | |
1879 | // if negative, it means we the timeout already occured |
1964 | // if negative, it means we the timeout already occurred |
1880 | if (after < 0.) |
1965 | if (after < 0.) |
1881 | { |
1966 | { |
1882 | // timeout occurred, take action |
1967 | // timeout occurred, take action |
1883 | } |
1968 | } |
1884 | else |
1969 | else |
… | |
… | |
1902 | |
1987 | |
1903 | Otherwise, we now the earliest time at which the timeout would trigger, |
1988 | Otherwise, we now the earliest time at which the timeout would trigger, |
1904 | and simply start the timer with this timeout value. |
1989 | and simply start the timer with this timeout value. |
1905 | |
1990 | |
1906 | In other words, each time the callback is invoked it will check whether |
1991 | In other words, each time the callback is invoked it will check whether |
1907 | the timeout cocured. If not, it will simply reschedule itself to check |
1992 | the timeout occurred. If not, it will simply reschedule itself to check |
1908 | again at the earliest time it could time out. Rinse. Repeat. |
1993 | again at the earliest time it could time out. Rinse. Repeat. |
1909 | |
1994 | |
1910 | This scheme causes more callback invocations (about one every 60 seconds |
1995 | This scheme causes more callback invocations (about one every 60 seconds |
1911 | minus half the average time between activity), but virtually no calls to |
1996 | minus half the average time between activity), but virtually no calls to |
1912 | libev to change the timeout. |
1997 | libev to change the timeout. |
… | |
… | |
1926 | if (activity detected) |
2011 | if (activity detected) |
1927 | last_activity = ev_now (EV_A); |
2012 | last_activity = ev_now (EV_A); |
1928 | |
2013 | |
1929 | When your timeout value changes, then the timeout can be changed by simply |
2014 | When your timeout value changes, then the timeout can be changed by simply |
1930 | providing a new value, stopping the timer and calling the callback, which |
2015 | providing a new value, stopping the timer and calling the callback, which |
1931 | will agaion do the right thing (for example, time out immediately :). |
2016 | will again do the right thing (for example, time out immediately :). |
1932 | |
2017 | |
1933 | timeout = new_value; |
2018 | timeout = new_value; |
1934 | ev_timer_stop (EV_A_ &timer); |
2019 | ev_timer_stop (EV_A_ &timer); |
1935 | callback (EV_A_ &timer, 0); |
2020 | callback (EV_A_ &timer, 0); |
1936 | |
2021 | |
… | |
… | |
2019 | |
2104 | |
2020 | The relative timeouts are calculated relative to the C<ev_now ()> |
2105 | The relative timeouts are calculated relative to the C<ev_now ()> |
2021 | 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 |
2022 | of the event triggering whatever timeout you are modifying/starting. If |
2107 | of the event triggering whatever timeout you are modifying/starting. If |
2023 | 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 |
2024 | 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 |
|
|
2110 | for it: |
2025 | |
2111 | |
2026 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
2112 | ev_timer_set (&timer, after + (ev_time () - ev_now ()), 0.); |
2027 | |
2113 | |
2028 | 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 |
2029 | 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 |
2030 | ()>. |
2116 | ()>, although that will push the event time of all outstanding events |
|
|
2117 | further into the future. |
2031 | |
2118 | |
2032 | =head3 The special problem of unsynchronised clocks |
2119 | =head3 The special problem of unsynchronised clocks |
2033 | |
2120 | |
2034 | 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 |
2035 | "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 |
… | |
… | |
2098 | |
2185 | |
2099 | =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) |
2100 | |
2187 | |
2101 | =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) |
2102 | |
2189 | |
2103 | Configure the timer to trigger after C<after> seconds. If C<repeat> |
2190 | Configure the timer to trigger after C<after> seconds (fractional and |
2104 | 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 |
2105 | reached. If it is positive, then the timer will automatically be |
2192 | automatically be stopped once the timeout is reached. If it is positive, |
2106 | configured to trigger again C<repeat> seconds later, again, and again, |
2193 | then the timer will automatically be configured to trigger again C<repeat> |
2107 | until stopped manually. |
2194 | seconds later, again, and again, until stopped manually. |
2108 | |
2195 | |
2109 | 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 |
2110 | 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 |
2111 | trigger at exactly 10 second intervals. If, however, your program cannot |
2198 | trigger at exactly 10 second intervals. If, however, your program cannot |
2112 | 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 |
… | |
… | |
2131 | =item If the timer is repeating, make the C<repeat> value the new timeout |
2218 | =item If the timer is repeating, make the C<repeat> value the new timeout |
2132 | and start the timer, if necessary. |
2219 | and start the timer, if necessary. |
2133 | |
2220 | |
2134 | =back |
2221 | =back |
2135 | |
2222 | |
2136 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
2223 | This sounds a bit complicated, see L</Be smart about timeouts>, above, for a |
2137 | usage example. |
2224 | usage example. |
2138 | |
2225 | |
2139 | =item ev_tstamp ev_timer_remaining (loop, ev_timer *) |
2226 | =item ev_tstamp ev_timer_remaining (loop, ev_timer *) |
2140 | |
2227 | |
2141 | Returns the remaining time until a timer fires. If the timer is active, |
2228 | Returns the remaining time until a timer fires. If the timer is active, |
… | |
… | |
2194 | 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 |
2195 | (and unfortunately a bit complex). |
2282 | (and unfortunately a bit complex). |
2196 | |
2283 | |
2197 | 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 |
2198 | 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 |
2199 | (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 |
2200 | 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 |
2201 | 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 |
2202 | wrist-watch). |
2289 | wrist-watch). |
2203 | |
2290 | |
2204 | 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 |
… | |
… | |
2209 | 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 |
2210 | it, as it uses a relative timeout). |
2297 | it, as it uses a relative timeout). |
2211 | |
2298 | |
2212 | 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 |
2213 | 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 |
2214 | 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> |
2215 | those cannot react to time jumps. |
2302 | watchers, as those cannot react to time jumps. |
2216 | |
2303 | |
2217 | 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 |
2218 | 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 |
2219 | 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 |
2220 | 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 |
… | |
… | |
2306 | |
2393 | |
2307 | 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 |
2308 | equal to the passed C<now> value >>. |
2395 | equal to the passed C<now> value >>. |
2309 | |
2396 | |
2310 | 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 |
2311 | 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 |
2312 | 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 |
2313 | 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 |
2314 | 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). |
2315 | |
2420 | |
2316 | =back |
2421 | =back |
2317 | |
2422 | |
2318 | =item ev_periodic_again (loop, ev_periodic *) |
2423 | =item ev_periodic_again (loop, ev_periodic *) |
2319 | |
2424 | |
… | |
… | |
2384 | |
2489 | |
2385 | ev_periodic hourly_tick; |
2490 | ev_periodic hourly_tick; |
2386 | ev_periodic_init (&hourly_tick, clock_cb, |
2491 | ev_periodic_init (&hourly_tick, clock_cb, |
2387 | fmod (ev_now (loop), 3600.), 3600., 0); |
2492 | fmod (ev_now (loop), 3600.), 3600., 0); |
2388 | ev_periodic_start (loop, &hourly_tick); |
2493 | ev_periodic_start (loop, &hourly_tick); |
2389 | |
2494 | |
2390 | |
2495 | |
2391 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
2496 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
2392 | |
2497 | |
2393 | 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 |
2394 | 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 |
… | |
… | |
2404 | 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 |
2405 | 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 |
2406 | 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 |
2407 | the moment, C<SIGCHLD> is permanently tied to the default loop. |
2512 | the moment, C<SIGCHLD> is permanently tied to the default loop. |
2408 | |
2513 | |
2409 | 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 |
2410 | 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 |
2411 | 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. |
2412 | |
2517 | |
2413 | If possible and supported, libev will install its handlers with |
2518 | If possible and supported, libev will install its handlers with |
2414 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2519 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2415 | 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 |
2416 | 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 |
… | |
… | |
2601 | |
2706 | |
2602 | =head2 C<ev_stat> - did the file attributes just change? |
2707 | =head2 C<ev_stat> - did the file attributes just change? |
2603 | |
2708 | |
2604 | 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 |
2605 | 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) |
2606 | 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 |
2607 | 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. |
2608 | |
2714 | |
2609 | 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 |
2610 | 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 |
2611 | 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 |
2612 | 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 |
… | |
… | |
2842 | Apart from keeping your process non-blocking (which is a useful |
2948 | Apart from keeping your process non-blocking (which is a useful |
2843 | effect on its own sometimes), idle watchers are a good place to do |
2949 | effect on its own sometimes), idle watchers are a good place to do |
2844 | "pseudo-background processing", or delay processing stuff to after the |
2950 | "pseudo-background processing", or delay processing stuff to after the |
2845 | event loop has handled all outstanding events. |
2951 | event loop has handled all outstanding events. |
2846 | |
2952 | |
|
|
2953 | =head3 Abusing an C<ev_idle> watcher for its side-effect |
|
|
2954 | |
|
|
2955 | As long as there is at least one active idle watcher, libev will never |
|
|
2956 | sleep unnecessarily. Or in other words, it will loop as fast as possible. |
|
|
2957 | For this to work, the idle watcher doesn't need to be invoked at all - the |
|
|
2958 | lowest priority will do. |
|
|
2959 | |
|
|
2960 | This mode of operation can be useful together with an C<ev_check> watcher, |
|
|
2961 | to do something on each event loop iteration - for example to balance load |
|
|
2962 | between different connections. |
|
|
2963 | |
|
|
2964 | See L</Abusing an ev_check watcher for its side-effect> for a longer |
|
|
2965 | example. |
|
|
2966 | |
2847 | =head3 Watcher-Specific Functions and Data Members |
2967 | =head3 Watcher-Specific Functions and Data Members |
2848 | |
2968 | |
2849 | =over 4 |
2969 | =over 4 |
2850 | |
2970 | |
2851 | =item ev_idle_init (ev_idle *, callback) |
2971 | =item ev_idle_init (ev_idle *, callback) |
… | |
… | |
2862 | callback, free it. Also, use no error checking, as usual. |
2982 | callback, free it. Also, use no error checking, as usual. |
2863 | |
2983 | |
2864 | static void |
2984 | static void |
2865 | idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
2985 | idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
2866 | { |
2986 | { |
|
|
2987 | // stop the watcher |
|
|
2988 | ev_idle_stop (loop, w); |
|
|
2989 | |
|
|
2990 | // now we can free it |
2867 | free (w); |
2991 | free (w); |
|
|
2992 | |
2868 | // now do something you wanted to do when the program has |
2993 | // now do something you wanted to do when the program has |
2869 | // no longer anything immediate to do. |
2994 | // no longer anything immediate to do. |
2870 | } |
2995 | } |
2871 | |
2996 | |
2872 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
2997 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
… | |
… | |
2874 | ev_idle_start (loop, idle_watcher); |
2999 | ev_idle_start (loop, idle_watcher); |
2875 | |
3000 | |
2876 | |
3001 | |
2877 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
3002 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
2878 | |
3003 | |
2879 | Prepare and check watchers are usually (but not always) used in pairs: |
3004 | Prepare and check watchers are often (but not always) used in pairs: |
2880 | prepare watchers get invoked before the process blocks and check watchers |
3005 | prepare watchers get invoked before the process blocks and check watchers |
2881 | afterwards. |
3006 | afterwards. |
2882 | |
3007 | |
2883 | 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 |
2884 | 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 |
2885 | watchers. Other loops than the current one are fine, however. The |
3010 | C<ev_check> watchers. Other loops than the current one are fine, |
2886 | 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 |
2887 | 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 |
2888 | 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 |
2889 | called in pairs bracketing the blocking call. |
3014 | kind they will always be called in pairs bracketing the blocking call. |
2890 | |
3015 | |
2891 | 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 |
2892 | 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 |
2893 | variable changes, implement your own watchers, integrate net-snmp or a |
3018 | variable changes, implement your own watchers, integrate net-snmp or a |
2894 | coroutine library and lots more. They are also occasionally useful if |
3019 | coroutine library and lots more. They are also occasionally useful if |
… | |
… | |
2912 | with priority higher than or equal to the event loop and one coroutine |
3037 | with priority higher than or equal to the event loop and one coroutine |
2913 | of lower priority, but only once, using idle watchers to keep the event |
3038 | of lower priority, but only once, using idle watchers to keep the event |
2914 | loop from blocking if lower-priority coroutines are active, thus mapping |
3039 | loop from blocking if lower-priority coroutines are active, thus mapping |
2915 | low-priority coroutines to idle/background tasks). |
3040 | low-priority coroutines to idle/background tasks). |
2916 | |
3041 | |
2917 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
3042 | When used for this purpose, it is recommended to give C<ev_check> watchers |
2918 | priority, to ensure that they are being run before any other watchers |
3043 | highest (C<EV_MAXPRI>) priority, to ensure that they are being run before |
2919 | after the poll (this doesn't matter for C<ev_prepare> watchers). |
3044 | any other watchers after the poll (this doesn't matter for C<ev_prepare> |
|
|
3045 | watchers). |
2920 | |
3046 | |
2921 | Also, C<ev_check> watchers (and C<ev_prepare> watchers, too) should not |
3047 | Also, C<ev_check> watchers (and C<ev_prepare> watchers, too) should not |
2922 | activate ("feed") events into libev. While libev fully supports this, they |
3048 | activate ("feed") events into libev. While libev fully supports this, they |
2923 | might get executed before other C<ev_check> watchers did their job. As |
3049 | might get executed before other C<ev_check> watchers did their job. As |
2924 | C<ev_check> watchers are often used to embed other (non-libev) event |
3050 | C<ev_check> watchers are often used to embed other (non-libev) event |
2925 | loops those other event loops might be in an unusable state until their |
3051 | loops those other event loops might be in an unusable state until their |
2926 | C<ev_check> watcher ran (always remind yourself to coexist peacefully with |
3052 | C<ev_check> watcher ran (always remind yourself to coexist peacefully with |
2927 | others). |
3053 | others). |
|
|
3054 | |
|
|
3055 | =head3 Abusing an C<ev_check> watcher for its side-effect |
|
|
3056 | |
|
|
3057 | C<ev_check> (and less often also C<ev_prepare>) watchers can also be |
|
|
3058 | useful because they are called once per event loop iteration. For |
|
|
3059 | example, if you want to handle a large number of connections fairly, you |
|
|
3060 | normally only do a bit of work for each active connection, and if there |
|
|
3061 | is more work to do, you wait for the next event loop iteration, so other |
|
|
3062 | connections have a chance of making progress. |
|
|
3063 | |
|
|
3064 | Using an C<ev_check> watcher is almost enough: it will be called on the |
|
|
3065 | next event loop iteration. However, that isn't as soon as possible - |
|
|
3066 | without external events, your C<ev_check> watcher will not be invoked. |
|
|
3067 | |
|
|
3068 | This is where C<ev_idle> watchers come in handy - all you need is a |
|
|
3069 | single global idle watcher that is active as long as you have one active |
|
|
3070 | C<ev_check> watcher. The C<ev_idle> watcher makes sure the event loop |
|
|
3071 | will not sleep, and the C<ev_check> watcher makes sure a callback gets |
|
|
3072 | invoked. Neither watcher alone can do that. |
2928 | |
3073 | |
2929 | =head3 Watcher-Specific Functions and Data Members |
3074 | =head3 Watcher-Specific Functions and Data Members |
2930 | |
3075 | |
2931 | =over 4 |
3076 | =over 4 |
2932 | |
3077 | |
… | |
… | |
3133 | |
3278 | |
3134 | =over 4 |
3279 | =over 4 |
3135 | |
3280 | |
3136 | =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) |
3137 | |
3282 | |
3138 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
3283 | =item ev_embed_set (ev_embed *, struct ev_loop *embedded_loop) |
3139 | |
3284 | |
3140 | Configures the watcher to embed the given loop, which must be |
3285 | Configures the watcher to embed the given loop, which must be |
3141 | 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 |
3142 | invoked automatically, otherwise it is the responsibility of the callback |
3287 | invoked automatically, otherwise it is the responsibility of the callback |
3143 | 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, |
… | |
… | |
3164 | used). |
3309 | used). |
3165 | |
3310 | |
3166 | struct ev_loop *loop_hi = ev_default_init (0); |
3311 | struct ev_loop *loop_hi = ev_default_init (0); |
3167 | struct ev_loop *loop_lo = 0; |
3312 | struct ev_loop *loop_lo = 0; |
3168 | ev_embed embed; |
3313 | ev_embed embed; |
3169 | |
3314 | |
3170 | // see if there is a chance of getting one that works |
3315 | // see if there is a chance of getting one that works |
3171 | // (remember that a flags value of 0 means autodetection) |
3316 | // (remember that a flags value of 0 means autodetection) |
3172 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3317 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3173 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3318 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3174 | : 0; |
3319 | : 0; |
… | |
… | |
3188 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
3333 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
3189 | |
3334 | |
3190 | struct ev_loop *loop = ev_default_init (0); |
3335 | struct ev_loop *loop = ev_default_init (0); |
3191 | struct ev_loop *loop_socket = 0; |
3336 | struct ev_loop *loop_socket = 0; |
3192 | ev_embed embed; |
3337 | ev_embed embed; |
3193 | |
3338 | |
3194 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3339 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3195 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3340 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3196 | { |
3341 | { |
3197 | ev_embed_init (&embed, 0, loop_socket); |
3342 | ev_embed_init (&embed, 0, loop_socket); |
3198 | ev_embed_start (loop, &embed); |
3343 | ev_embed_start (loop, &embed); |
… | |
… | |
3206 | |
3351 | |
3207 | =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 |
3208 | |
3353 | |
3209 | 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 |
3210 | 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 |
3211 | 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 |
3212 | 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 |
3213 | 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 |
3214 | 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, |
3215 | handlers will be invoked, too, of course. |
3360 | of course. |
3216 | |
3361 | |
3217 | =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? |
3218 | |
3363 | |
3219 | 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 |
3220 | 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 |
3221 | sequence should be handled by libev without any problems. |
3366 | sequence should be handled by libev without any problems. |
3222 | |
3367 | |
3223 | This changes when the application actually wants to do event handling |
3368 | This changes when the application actually wants to do event handling |
3224 | 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 |
… | |
… | |
3313 | it by calling C<ev_async_send>, which is thread- and signal safe. |
3458 | it by calling C<ev_async_send>, which is thread- and signal safe. |
3314 | |
3459 | |
3315 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3460 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3316 | too, are asynchronous in nature, and signals, too, will be compressed |
3461 | too, are asynchronous in nature, and signals, too, will be compressed |
3317 | (i.e. the number of callback invocations may be less than the number of |
3462 | (i.e. the number of callback invocations may be less than the number of |
3318 | C<ev_async_sent> calls). In fact, you could use signal watchers as a kind |
3463 | C<ev_async_send> calls). In fact, you could use signal watchers as a kind |
3319 | of "global async watchers" by using a watcher on an otherwise unused |
3464 | of "global async watchers" by using a watcher on an otherwise unused |
3320 | signal, and C<ev_feed_signal> to signal this watcher from another thread, |
3465 | signal, and C<ev_feed_signal> to signal this watcher from another thread, |
3321 | even without knowing which loop owns the signal. |
3466 | even without knowing which loop owns the signal. |
3322 | |
3467 | |
3323 | =head3 Queueing |
3468 | =head3 Queueing |
… | |
… | |
3462 | |
3607 | |
3463 | There are some other functions of possible interest. Described. Here. Now. |
3608 | There are some other functions of possible interest. Described. Here. Now. |
3464 | |
3609 | |
3465 | =over 4 |
3610 | =over 4 |
3466 | |
3611 | |
3467 | =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) |
3468 | |
3613 | |
3469 | 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 |
3470 | callback on whichever event happens first and automatically stops both |
3615 | callback on whichever event happens first and automatically stops both |
3471 | 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 |
3472 | 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 |
… | |
… | |
3614 | already been invoked. |
3759 | already been invoked. |
3615 | |
3760 | |
3616 | 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 |
3617 | 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 |
3618 | C<start_new_request> immediately knows the result, it can artificially |
3763 | C<start_new_request> immediately knows the result, it can artificially |
3619 | 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 |
3620 | for example, or more sneakily, by reusing an existing (stopped) watcher |
3765 | example, or more sneakily, by reusing an existing (stopped) watcher and |
3621 | and pushing it into the pending queue: |
3766 | pushing it into the pending queue: |
3622 | |
3767 | |
3623 | ev_set_cb (watcher, callback); |
3768 | ev_set_cb (watcher, callback); |
3624 | ev_feed_event (EV_A_ watcher, 0); |
3769 | ev_feed_event (EV_A_ watcher, 0); |
3625 | |
3770 | |
3626 | 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 |
… | |
… | |
3634 | |
3779 | |
3635 | 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 |
3636 | 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 |
3637 | 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 |
3638 | 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 |
3639 | 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. |
3640 | |
3785 | |
3641 | 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> |
3642 | 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 |
3643 | triggered, using C<EVRUN_ONCE>: |
3788 | triggered, using C<EVRUN_ONCE>: |
3644 | |
3789 | |
… | |
… | |
3830 | called): |
3975 | called): |
3831 | |
3976 | |
3832 | void |
3977 | void |
3833 | wait_for_event (ev_watcher *w) |
3978 | wait_for_event (ev_watcher *w) |
3834 | { |
3979 | { |
3835 | ev_cb_set (w) = current_coro; |
3980 | ev_set_cb (w, current_coro); |
3836 | switch_to (libev_coro); |
3981 | switch_to (libev_coro); |
3837 | } |
3982 | } |
3838 | |
3983 | |
3839 | That basically suspends the coroutine inside C<wait_for_event> and |
3984 | That basically suspends the coroutine inside C<wait_for_event> and |
3840 | continues the libev coroutine, which, when appropriate, switches back to |
3985 | continues the libev coroutine, which, when appropriate, switches back to |
… | |
… | |
3843 | You can do similar tricks if you have, say, threads with an event queue - |
3988 | You can do similar tricks if you have, say, threads with an event queue - |
3844 | instead of storing a coroutine, you store the queue object and instead of |
3989 | instead of storing a coroutine, you store the queue object and instead of |
3845 | switching to a coroutine, you push the watcher onto the queue and notify |
3990 | switching to a coroutine, you push the watcher onto the queue and notify |
3846 | any waiters. |
3991 | any waiters. |
3847 | |
3992 | |
3848 | 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 |
3849 | 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: |
3850 | |
3995 | |
3851 | // my_ev.h |
3996 | // my_ev.h |
3852 | #define EV_CB_DECLARE(type) struct my_coro *cb; |
3997 | #define EV_CB_DECLARE(type) struct my_coro *cb; |
3853 | #define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb); |
3998 | #define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb) |
3854 | #include "../libev/ev.h" |
3999 | #include "../libev/ev.h" |
3855 | |
4000 | |
3856 | // my_ev.c |
4001 | // my_ev.c |
3857 | #define EV_H "my_ev.h" |
4002 | #define EV_H "my_ev.h" |
3858 | #include "../libev/ev.c" |
4003 | #include "../libev/ev.c" |
… | |
… | |
3897 | |
4042 | |
3898 | =back |
4043 | =back |
3899 | |
4044 | |
3900 | =head1 C++ SUPPORT |
4045 | =head1 C++ SUPPORT |
3901 | |
4046 | |
|
|
4047 | =head2 C API |
|
|
4048 | |
|
|
4049 | The normal C API should work fine when used from C++: both ev.h and the |
|
|
4050 | libev sources can be compiled as C++. Therefore, code that uses the C API |
|
|
4051 | will work fine. |
|
|
4052 | |
|
|
4053 | Proper exception specifications might have to be added to callbacks passed |
|
|
4054 | to libev: exceptions may be thrown only from watcher callbacks, all other |
|
|
4055 | callbacks (allocator, syserr, loop acquire/release and periodic reschedule |
|
|
4056 | callbacks) must not throw exceptions, and might need a C<noexcept> |
|
|
4057 | specification. If you have code that needs to be compiled as both C and |
|
|
4058 | C++ you can use the C<EV_NOEXCEPT> macro for this: |
|
|
4059 | |
|
|
4060 | static void |
|
|
4061 | fatal_error (const char *msg) EV_NOEXCEPT |
|
|
4062 | { |
|
|
4063 | perror (msg); |
|
|
4064 | abort (); |
|
|
4065 | } |
|
|
4066 | |
|
|
4067 | ... |
|
|
4068 | ev_set_syserr_cb (fatal_error); |
|
|
4069 | |
|
|
4070 | The only API functions that can currently throw exceptions are C<ev_run>, |
|
|
4071 | C<ev_invoke>, C<ev_invoke_pending> and C<ev_loop_destroy> (the latter |
|
|
4072 | because it runs cleanup watchers). |
|
|
4073 | |
|
|
4074 | Throwing exceptions in watcher callbacks is only supported if libev itself |
|
|
4075 | is compiled with a C++ compiler or your C and C++ environments allow |
|
|
4076 | throwing exceptions through C libraries (most do). |
|
|
4077 | |
|
|
4078 | =head2 C++ API |
|
|
4079 | |
3902 | 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 |
3903 | 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 |
3904 | the callback model to a model using method callbacks on objects. |
4082 | the callback model to a model using method callbacks on objects. |
3905 | |
4083 | |
3906 | To use it, |
4084 | To use it, |
3907 | |
4085 | |
3908 | #include <ev++.h> |
4086 | #include <ev++.h> |
3909 | |
4087 | |
3910 | 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 |
3911 | 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 |
3912 | 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 |
… | |
… | |
4015 | void operator() (ev::io &w, int revents) |
4193 | void operator() (ev::io &w, int revents) |
4016 | { |
4194 | { |
4017 | ... |
4195 | ... |
4018 | } |
4196 | } |
4019 | } |
4197 | } |
4020 | |
4198 | |
4021 | myfunctor f; |
4199 | myfunctor f; |
4022 | |
4200 | |
4023 | ev::io w; |
4201 | ev::io w; |
4024 | w.set (&f); |
4202 | w.set (&f); |
4025 | |
4203 | |
… | |
… | |
4043 | 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 |
4044 | do this when the watcher is inactive (and not pending either). |
4222 | do this when the watcher is inactive (and not pending either). |
4045 | |
4223 | |
4046 | =item w->set ([arguments]) |
4224 | =item w->set ([arguments]) |
4047 | |
4225 | |
4048 | 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>), |
4049 | 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 |
4050 | C counterpart, an active watcher gets automatically stopped and restarted |
4228 | must be called at least once. Unlike the C counterpart, an active watcher |
4051 | 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. |
4052 | |
4234 | |
4053 | =item w->start () |
4235 | =item w->start () |
4054 | |
4236 | |
4055 | 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 |
4056 | constructor already stores the event loop. |
4238 | constructor already stores the event loop. |
… | |
… | |
4160 | |
4342 | |
4161 | 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 |
4162 | 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 |
4163 | L<http://github.com/brimworks/lua-ev>. |
4345 | L<http://github.com/brimworks/lua-ev>. |
4164 | |
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 | |
4165 | =back |
4355 | =back |
4166 | |
4356 | |
4167 | |
4357 | |
4168 | =head1 MACRO MAGIC |
4358 | =head1 MACRO MAGIC |
4169 | |
4359 | |
… | |
… | |
4286 | ev_vars.h |
4476 | ev_vars.h |
4287 | ev_wrap.h |
4477 | ev_wrap.h |
4288 | |
4478 | |
4289 | ev_win32.c required on win32 platforms only |
4479 | ev_win32.c required on win32 platforms only |
4290 | |
4480 | |
4291 | ev_select.c only when select backend is enabled (which is enabled by default) |
4481 | ev_select.c only when select backend is enabled |
4292 | ev_poll.c only when poll backend is enabled (disabled by default) |
4482 | ev_poll.c only when poll backend is enabled |
4293 | 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 |
4294 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
4485 | ev_kqueue.c only when the kqueue backend is enabled |
4295 | 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 |
4296 | |
4487 | |
4297 | 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 |
4298 | to compile this single file. |
4489 | to compile this single file. |
4299 | |
4490 | |
4300 | =head3 LIBEVENT COMPATIBILITY API |
4491 | =head3 LIBEVENT COMPATIBILITY API |
… | |
… | |
4468 | 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 |
4469 | 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 |
4470 | file descriptors again. Note that the replacement function has to close |
4661 | file descriptors again. Note that the replacement function has to close |
4471 | the underlying OS handle. |
4662 | the underlying OS handle. |
4472 | |
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 | |
4473 | =item EV_USE_POLL |
4671 | =item EV_USE_POLL |
4474 | |
4672 | |
4475 | 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) |
4476 | backend. Otherwise it will be enabled on non-win32 platforms. It |
4674 | backend. Otherwise it will be enabled on non-win32 platforms. It |
4477 | takes precedence over select. |
4675 | takes precedence over select. |
… | |
… | |
4481 | 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 |
4482 | C<epoll>(7) backend. Its availability will be detected at runtime, |
4680 | C<epoll>(7) backend. Its availability will be detected at runtime, |
4483 | 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 |
4484 | 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 |
4485 | 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. |
4486 | |
4691 | |
4487 | =item EV_USE_KQUEUE |
4692 | =item EV_USE_KQUEUE |
4488 | |
4693 | |
4489 | 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 |
4490 | 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, |
… | |
… | |
4521 | different cpus (or different cpu cores). This reduces dependencies |
4726 | different cpus (or different cpu cores). This reduces dependencies |
4522 | and makes libev faster. |
4727 | and makes libev faster. |
4523 | |
4728 | |
4524 | =item EV_NO_THREADS |
4729 | =item EV_NO_THREADS |
4525 | |
4730 | |
4526 | 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 |
4527 | from different threads, which is a stronger assumption than C<EV_NO_SMP>, |
4732 | different threads (that includes signal handlers), which is a stronger |
4528 | above. This reduces dependencies and makes libev faster. |
4733 | assumption than C<EV_NO_SMP>, above. This reduces dependencies and makes |
|
|
4734 | libev faster. |
4529 | |
4735 | |
4530 | =item EV_ATOMIC_T |
4736 | =item EV_ATOMIC_T |
4531 | |
4737 | |
4532 | 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 |
4533 | 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 |
4534 | 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 |
4535 | 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 |
4536 | 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> |
4537 | in C<ev_async> watchers. |
4743 | watchers. |
4538 | |
4744 | |
4539 | 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> |
4540 | (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. |
4541 | although strictly speaking using a type that also implies a memory fence |
|
|
4542 | is required. |
|
|
4543 | |
4747 | |
4544 | =item EV_H (h) |
4748 | =item EV_H (h) |
4545 | |
4749 | |
4546 | 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 |
4547 | 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 |
… | |
… | |
4915 | default loop and triggering an C<ev_async> watcher from the default loop |
5119 | default loop and triggering an C<ev_async> watcher from the default loop |
4916 | watcher callback into the event loop interested in the signal. |
5120 | watcher callback into the event loop interested in the signal. |
4917 | |
5121 | |
4918 | =back |
5122 | =back |
4919 | |
5123 | |
4920 | See also L<THREAD LOCKING EXAMPLE>. |
5124 | See also L</THREAD LOCKING EXAMPLE>. |
4921 | |
5125 | |
4922 | =head3 COROUTINES |
5126 | =head3 COROUTINES |
4923 | |
5127 | |
4924 | Libev is very accommodating to coroutines ("cooperative threads"): |
5128 | Libev is very accommodating to coroutines ("cooperative threads"): |
4925 | libev fully supports nesting calls to its functions from different |
5129 | libev fully supports nesting calls to its functions from different |
… | |
… | |
5194 | 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 |
5195 | 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 |
5196 | callback: The watcher callbacks have different type signatures, but libev |
5400 | callback: The watcher callbacks have different type signatures, but libev |
5197 | calls them using an C<ev_watcher *> internally. |
5401 | calls them using an C<ev_watcher *> internally. |
5198 | |
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 | |
5199 | =item pointer accesses must be thread-atomic |
5408 | =item pointer accesses must be thread-atomic |
5200 | |
5409 | |
5201 | 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 |
5202 | 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. |
5203 | |
5412 | |
… | |
… | |
5216 | thread" or will block signals process-wide, both behaviours would |
5425 | thread" or will block signals process-wide, both behaviours would |
5217 | be compatible with libev. Interaction between C<sigprocmask> and |
5426 | be compatible with libev. Interaction between C<sigprocmask> and |
5218 | C<pthread_sigmask> could complicate things, however. |
5427 | C<pthread_sigmask> could complicate things, however. |
5219 | |
5428 | |
5220 | 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 |
5221 | 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 |
5222 | well. |
5431 | thread as well. |
5223 | |
5432 | |
5224 | =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 |
5225 | |
5434 | |
5226 | 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 |
5227 | 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 |
… | |
… | |
5331 | =over 4 |
5540 | =over 4 |
5332 | |
5541 | |
5333 | =item C<EV_COMPAT3> backwards compatibility mechanism |
5542 | =item C<EV_COMPAT3> backwards compatibility mechanism |
5334 | |
5543 | |
5335 | The backward compatibility mechanism can be controlled by |
5544 | The backward compatibility mechanism can be controlled by |
5336 | 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> |
5337 | section. |
5546 | section. |
5338 | |
5547 | |
5339 | =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 |
5340 | |
5549 | |
5341 | 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: |
… | |
… | |
5384 | =over 4 |
5593 | =over 4 |
5385 | |
5594 | |
5386 | =item active |
5595 | =item active |
5387 | |
5596 | |
5388 | A watcher is active as long as it has been started and not yet stopped. |
5597 | A watcher is active as long as it has been started and not yet stopped. |
5389 | See L<WATCHER STATES> for details. |
5598 | See L</WATCHER STATES> for details. |
5390 | |
5599 | |
5391 | =item application |
5600 | =item application |
5392 | |
5601 | |
5393 | In this document, an application is whatever is using libev. |
5602 | In this document, an application is whatever is using libev. |
5394 | |
5603 | |
… | |
… | |
5430 | watchers and events. |
5639 | watchers and events. |
5431 | |
5640 | |
5432 | =item pending |
5641 | =item pending |
5433 | |
5642 | |
5434 | A watcher is pending as soon as the corresponding event has been |
5643 | A watcher is pending as soon as the corresponding event has been |
5435 | detected. See L<WATCHER STATES> for details. |
5644 | detected. See L</WATCHER STATES> for details. |
5436 | |
5645 | |
5437 | =item real time |
5646 | =item real time |
5438 | |
5647 | |
5439 | The physical time that is observed. It is apparently strictly monotonic :) |
5648 | The physical time that is observed. It is apparently strictly monotonic :) |
5440 | |
5649 | |