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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. |
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581 | |
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582 | If this backend works for you (as of this writing, it was very |
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583 | experimental), it is the best event interface available on linux and might |
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584 | be well worth enabling it - if it isn't available in your kernel this will |
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585 | be detected and this backend will be skipped. |
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586 | |
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587 | This backend can batch oneshot requests and supports a user-space ring |
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588 | buffer to receive events. It also doesn't suffer from most of the design |
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589 | problems of epoll (such as not being able to remove event sources from |
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590 | the epoll set), and generally sounds too good to be true. Because, this |
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591 | being the linux kernel, of course it suffers from a whole new set of |
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592 | limitations. |
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593 | |
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594 | For one, it is not easily embeddable (but probably could be done using |
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595 | an event fd at some extra overhead). It also is subject to a system wide |
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596 | limit that can be configured in F</proc/sys/fs/aio-max-nr> - each loop |
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597 | currently requires C<61> of this number. If no aio requests are left, this |
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598 | backend will be skipped during initialisation. |
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599 | |
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600 | Most problematic in practise, however, is that not all file descriptors |
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601 | work with it. For example, in linux 5.1, tcp sockets, pipes, event fds, |
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602 | files, F</dev/null> and a few others are supported, but ttys do not work |
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603 | properly (a known bug that the kernel developers don't care about, see |
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604 | L<https://lore.kernel.org/patchwork/patch/1047453/>), so this is not |
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605 | (yet?) a generic event polling interface. |
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606 | |
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607 | To work around this latter problem, the current version of libev uses |
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608 | epoll as a fallback for file deescriptor types that do not work. Epoll |
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609 | is used in, kind of, slow mode that hopefully avoids most of its design |
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610 | problems and requires 1-3 extra syscalls per active fd every iteration. |
548 | |
611 | |
549 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
612 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
550 | C<EVBACKEND_POLL>. |
613 | C<EVBACKEND_POLL>. |
551 | |
614 | |
552 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
615 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
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567 | |
630 | |
568 | It scales in the same way as the epoll backend, but the interface to the |
631 | It scales in the same way as the epoll backend, but the interface to the |
569 | kernel is more efficient (which says nothing about its actual speed, of |
632 | 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 |
633 | 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 |
634 | 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 (but |
635 | two event changes per incident. Support for C<fork ()> is very bad (you |
573 | sane, unlike epoll) and it drops fds silently in similarly hard-to-detect |
636 | might have to leak fd's on fork, but it's more sane than epoll) and it |
574 | cases |
637 | drops fds silently in similarly hard-to-detect cases. |
575 | |
638 | |
576 | This backend usually performs well under most conditions. |
639 | This backend usually performs well under most conditions. |
577 | |
640 | |
578 | While nominally embeddable in other event loops, this doesn't work |
641 | 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 |
642 | 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 |
716 | Example: Use whatever libev has to offer, but make sure that kqueue is |
654 | used if available. |
717 | used if available. |
655 | |
718 | |
656 | struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE); |
719 | struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE); |
657 | |
720 | |
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721 | Example: Similarly, on linux, you mgiht want to take advantage of the |
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722 | linux aio backend if possible, but fall back to something else if that |
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723 | isn't available. |
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724 | |
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725 | struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_LINUXAIO); |
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726 | |
658 | =item ev_loop_destroy (loop) |
727 | =item ev_loop_destroy (loop) |
659 | |
728 | |
660 | Destroys an event loop object (frees all memory and kernel state |
729 | 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 |
730 | 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 |
731 | 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> |
747 | If you need dynamically allocated loops it is better to use C<ev_loop_new> |
679 | and C<ev_loop_destroy>. |
748 | and C<ev_loop_destroy>. |
680 | |
749 | |
681 | =item ev_loop_fork (loop) |
750 | =item ev_loop_fork (loop) |
682 | |
751 | |
683 | This function sets a flag that causes subsequent C<ev_run> iterations to |
752 | This function sets a flag that causes subsequent C<ev_run> iterations |
684 | reinitialise the kernel state for backends that have one. Despite the |
753 | 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 |
754 | 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 |
755 | watchers (except inside an C<ev_prepare> callback), but it makes most |
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756 | sense after forking, in the child process. You I<must> call it (or use |
687 | child before resuming or calling C<ev_run>. |
757 | C<EVFLAG_FORKCHECK>) in the child before resuming or calling C<ev_run>. |
688 | |
758 | |
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759 | In addition, if you want to reuse a loop (via this function or |
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760 | C<EVFLAG_FORKCHECK>), you I<also> have to ignore C<SIGPIPE>. |
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761 | |
689 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
762 | 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 |
763 | 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 |
764 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
692 | during fork. |
765 | during fork. |
693 | |
766 | |
694 | On the other hand, you only need to call this function in the child |
767 | On the other hand, you only need to call this function in the child |
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764 | |
837 | |
765 | This function is rarely useful, but when some event callback runs for a |
838 | 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 |
839 | very long time without entering the event loop, updating libev's idea of |
767 | the current time is a good idea. |
840 | the current time is a good idea. |
768 | |
841 | |
769 | See also L<The special problem of time updates> in the C<ev_timer> section. |
842 | See also L</The special problem of time updates> in the C<ev_timer> section. |
770 | |
843 | |
771 | =item ev_suspend (loop) |
844 | =item ev_suspend (loop) |
772 | |
845 | |
773 | =item ev_resume (loop) |
846 | =item ev_resume (loop) |
774 | |
847 | |
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792 | without a previous call to C<ev_suspend>. |
865 | without a previous call to C<ev_suspend>. |
793 | |
866 | |
794 | Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the |
867 | Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the |
795 | event loop time (see C<ev_now_update>). |
868 | event loop time (see C<ev_now_update>). |
796 | |
869 | |
797 | =item ev_run (loop, int flags) |
870 | =item bool ev_run (loop, int flags) |
798 | |
871 | |
799 | Finally, this is it, the event handler. This function usually is called |
872 | Finally, this is it, the event handler. This function usually is called |
800 | after you have initialised all your watchers and you want to start |
873 | after you have initialised all your watchers and you want to start |
801 | handling events. It will ask the operating system for any new events, call |
874 | handling events. It will ask the operating system for any new events, call |
802 | the watcher callbacks, an then repeat the whole process indefinitely: This |
875 | the watcher callbacks, and then repeat the whole process indefinitely: This |
803 | is why event loops are called I<loops>. |
876 | is why event loops are called I<loops>. |
804 | |
877 | |
805 | If the flags argument is specified as C<0>, it will keep handling events |
878 | If the flags argument is specified as C<0>, it will keep handling events |
806 | until either no event watchers are active anymore or C<ev_break> was |
879 | until either no event watchers are active anymore or C<ev_break> was |
807 | called. |
880 | called. |
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881 | |
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882 | The return value is false if there are no more active watchers (which |
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883 | usually means "all jobs done" or "deadlock"), and true in all other cases |
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884 | (which usually means " you should call C<ev_run> again"). |
808 | |
885 | |
809 | Please note that an explicit C<ev_break> is usually better than |
886 | Please note that an explicit C<ev_break> is usually better than |
810 | relying on all watchers to be stopped when deciding when a program has |
887 | relying on all watchers to be stopped when deciding when a program has |
811 | finished (especially in interactive programs), but having a program |
888 | finished (especially in interactive programs), but having a program |
812 | that automatically loops as long as it has to and no longer by virtue |
889 | that automatically loops as long as it has to and no longer by virtue |
813 | of relying on its watchers stopping correctly, that is truly a thing of |
890 | of relying on its watchers stopping correctly, that is truly a thing of |
814 | beauty. |
891 | beauty. |
815 | |
892 | |
816 | This function is also I<mostly> exception-safe - you can break out of |
893 | This function is I<mostly> exception-safe - you can break out of a |
817 | a C<ev_run> call by calling C<longjmp> in a callback, throwing a C++ |
894 | C<ev_run> call by calling C<longjmp> in a callback, throwing a C++ |
818 | exception and so on. This does not decrement the C<ev_depth> value, nor |
895 | exception and so on. This does not decrement the C<ev_depth> value, nor |
819 | will it clear any outstanding C<EVBREAK_ONE> breaks. |
896 | will it clear any outstanding C<EVBREAK_ONE> breaks. |
820 | |
897 | |
821 | A flags value of C<EVRUN_NOWAIT> will look for new events, will handle |
898 | A flags value of C<EVRUN_NOWAIT> will look for new events, will handle |
822 | those events and any already outstanding ones, but will not wait and |
899 | those events and any already outstanding ones, but will not wait and |
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1012 | invoke the actual watchers inside another context (another thread etc.). |
1089 | invoke the actual watchers inside another context (another thread etc.). |
1013 | |
1090 | |
1014 | If you want to reset the callback, use C<ev_invoke_pending> as new |
1091 | If you want to reset the callback, use C<ev_invoke_pending> as new |
1015 | callback. |
1092 | callback. |
1016 | |
1093 | |
1017 | =item ev_set_loop_release_cb (loop, void (*release)(EV_P), void (*acquire)(EV_P)) |
1094 | =item ev_set_loop_release_cb (loop, void (*release)(EV_P) throw (), void (*acquire)(EV_P) throw ()) |
1018 | |
1095 | |
1019 | Sometimes you want to share the same loop between multiple threads. This |
1096 | Sometimes you want to share the same loop between multiple threads. This |
1020 | can be done relatively simply by putting mutex_lock/unlock calls around |
1097 | can be done relatively simply by putting mutex_lock/unlock calls around |
1021 | each call to a libev function. |
1098 | each call to a libev function. |
1022 | |
1099 | |
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… | |
1170 | |
1247 | |
1171 | =item C<EV_PREPARE> |
1248 | =item C<EV_PREPARE> |
1172 | |
1249 | |
1173 | =item C<EV_CHECK> |
1250 | =item C<EV_CHECK> |
1174 | |
1251 | |
1175 | All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts |
1252 | All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts to |
1176 | to gather new events, and all C<ev_check> watchers are invoked just after |
1253 | gather new events, and all C<ev_check> watchers are queued (not invoked) |
1177 | C<ev_run> has gathered them, but before it invokes any callbacks for any |
1254 | just after C<ev_run> has gathered them, but before it queues any callbacks |
|
|
1255 | for any received events. That means C<ev_prepare> watchers are the last |
|
|
1256 | watchers invoked before the event loop sleeps or polls for new events, and |
|
|
1257 | C<ev_check> watchers will be invoked before any other watchers of the same |
|
|
1258 | or lower priority within an event loop iteration. |
|
|
1259 | |
1178 | received events. Callbacks of both watcher types can start and stop as |
1260 | Callbacks of both watcher types can start and stop as many watchers as |
1179 | many watchers as they want, and all of them will be taken into account |
1261 | they want, and all of them will be taken into account (for example, a |
1180 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
1262 | C<ev_prepare> watcher might start an idle watcher to keep C<ev_run> from |
1181 | C<ev_run> from blocking). |
1263 | blocking). |
1182 | |
1264 | |
1183 | =item C<EV_EMBED> |
1265 | =item C<EV_EMBED> |
1184 | |
1266 | |
1185 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1267 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1186 | |
1268 | |
… | |
… | |
1309 | |
1391 | |
1310 | =item callback ev_cb (ev_TYPE *watcher) |
1392 | =item callback ev_cb (ev_TYPE *watcher) |
1311 | |
1393 | |
1312 | Returns the callback currently set on the watcher. |
1394 | Returns the callback currently set on the watcher. |
1313 | |
1395 | |
1314 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1396 | =item ev_set_cb (ev_TYPE *watcher, callback) |
1315 | |
1397 | |
1316 | Change the callback. You can change the callback at virtually any time |
1398 | Change the callback. You can change the callback at virtually any time |
1317 | (modulo threads). |
1399 | (modulo threads). |
1318 | |
1400 | |
1319 | =item ev_set_priority (ev_TYPE *watcher, int priority) |
1401 | =item ev_set_priority (ev_TYPE *watcher, int priority) |
… | |
… | |
1337 | or might not have been clamped to the valid range. |
1419 | or might not have been clamped to the valid range. |
1338 | |
1420 | |
1339 | The default priority used by watchers when no priority has been set is |
1421 | The default priority used by watchers when no priority has been set is |
1340 | always C<0>, which is supposed to not be too high and not be too low :). |
1422 | always C<0>, which is supposed to not be too high and not be too low :). |
1341 | |
1423 | |
1342 | See L<WATCHER PRIORITY MODELS>, below, for a more thorough treatment of |
1424 | See L</WATCHER PRIORITY MODELS>, below, for a more thorough treatment of |
1343 | priorities. |
1425 | priorities. |
1344 | |
1426 | |
1345 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
1427 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
1346 | |
1428 | |
1347 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
1429 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
… | |
… | |
1372 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
1454 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
1373 | functions that do not need a watcher. |
1455 | functions that do not need a watcher. |
1374 | |
1456 | |
1375 | =back |
1457 | =back |
1376 | |
1458 | |
1377 | See also the L<ASSOCIATING CUSTOM DATA WITH A WATCHER> and L<BUILDING YOUR |
1459 | See also the L</ASSOCIATING CUSTOM DATA WITH A WATCHER> and L</BUILDING YOUR |
1378 | OWN COMPOSITE WATCHERS> idioms. |
1460 | OWN COMPOSITE WATCHERS> idioms. |
1379 | |
1461 | |
1380 | =head2 WATCHER STATES |
1462 | =head2 WATCHER STATES |
1381 | |
1463 | |
1382 | There are various watcher states mentioned throughout this manual - |
1464 | There are various watcher states mentioned throughout this manual - |
… | |
… | |
1384 | transition between them will be described in more detail - and while these |
1466 | transition between them will be described in more detail - and while these |
1385 | rules might look complicated, they usually do "the right thing". |
1467 | rules might look complicated, they usually do "the right thing". |
1386 | |
1468 | |
1387 | =over 4 |
1469 | =over 4 |
1388 | |
1470 | |
1389 | =item initialiased |
1471 | =item initialised |
1390 | |
1472 | |
1391 | Before a watcher can be registered with the event loop it has to be |
1473 | Before a watcher can be registered with the event loop it has to be |
1392 | initialised. This can be done with a call to C<ev_TYPE_init>, or calls to |
1474 | initialised. This can be done with a call to C<ev_TYPE_init>, or calls to |
1393 | C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
1475 | C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
1394 | |
1476 | |
… | |
… | |
1592 | |
1674 | |
1593 | But really, best use non-blocking mode. |
1675 | But really, best use non-blocking mode. |
1594 | |
1676 | |
1595 | =head3 The special problem of disappearing file descriptors |
1677 | =head3 The special problem of disappearing file descriptors |
1596 | |
1678 | |
1597 | Some backends (e.g. kqueue, epoll) need to be told about closing a file |
1679 | Some backends (e.g. kqueue, epoll, linuxaio) need to be told about closing |
1598 | descriptor (either due to calling C<close> explicitly or any other means, |
1680 | a file descriptor (either due to calling C<close> explicitly or any other |
1599 | such as C<dup2>). The reason is that you register interest in some file |
1681 | means, such as C<dup2>). The reason is that you register interest in some |
1600 | descriptor, but when it goes away, the operating system will silently drop |
1682 | file descriptor, but when it goes away, the operating system will silently |
1601 | this interest. If another file descriptor with the same number then is |
1683 | drop this interest. If another file descriptor with the same number then |
1602 | registered with libev, there is no efficient way to see that this is, in |
1684 | is registered with libev, there is no efficient way to see that this is, |
1603 | fact, a different file descriptor. |
1685 | in fact, a different file descriptor. |
1604 | |
1686 | |
1605 | To avoid having to explicitly tell libev about such cases, libev follows |
1687 | To avoid having to explicitly tell libev about such cases, libev follows |
1606 | the following policy: Each time C<ev_io_set> is being called, libev |
1688 | the following policy: Each time C<ev_io_set> is being called, libev |
1607 | will assume that this is potentially a new file descriptor, otherwise |
1689 | will assume that this is potentially a new file descriptor, otherwise |
1608 | it is assumed that the file descriptor stays the same. That means that |
1690 | it is assumed that the file descriptor stays the same. That means that |
… | |
… | |
1657 | when you rarely read from a file instead of from a socket, and want to |
1739 | when you rarely read from a file instead of from a socket, and want to |
1658 | reuse the same code path. |
1740 | reuse the same code path. |
1659 | |
1741 | |
1660 | =head3 The special problem of fork |
1742 | =head3 The special problem of fork |
1661 | |
1743 | |
1662 | Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit |
1744 | Some backends (epoll, kqueue, probably linuxaio) do not support C<fork ()> |
1663 | useless behaviour. Libev fully supports fork, but needs to be told about |
1745 | at all or exhibit useless behaviour. Libev fully supports fork, but needs |
1664 | it in the child if you want to continue to use it in the child. |
1746 | to be told about it in the child if you want to continue to use it in the |
|
|
1747 | child. |
1665 | |
1748 | |
1666 | To support fork in your child processes, you have to call C<ev_loop_fork |
1749 | To support fork in your child processes, you have to call C<ev_loop_fork |
1667 | ()> after a fork in the child, enable C<EVFLAG_FORKCHECK>, or resort to |
1750 | ()> after a fork in the child, enable C<EVFLAG_FORKCHECK>, or resort to |
1668 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
1751 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
1669 | |
1752 | |
… | |
… | |
1870 | callback (EV_P_ ev_timer *w, int revents) |
1953 | callback (EV_P_ ev_timer *w, int revents) |
1871 | { |
1954 | { |
1872 | // calculate when the timeout would happen |
1955 | // calculate when the timeout would happen |
1873 | ev_tstamp after = last_activity - ev_now (EV_A) + timeout; |
1956 | ev_tstamp after = last_activity - ev_now (EV_A) + timeout; |
1874 | |
1957 | |
1875 | // if negative, it means we the timeout already occured |
1958 | // if negative, it means we the timeout already occurred |
1876 | if (after < 0.) |
1959 | if (after < 0.) |
1877 | { |
1960 | { |
1878 | // timeout occurred, take action |
1961 | // timeout occurred, take action |
1879 | } |
1962 | } |
1880 | else |
1963 | else |
1881 | { |
1964 | { |
1882 | // callback was invoked, but there was some recent |
1965 | // callback was invoked, but there was some recent |
1883 | // activity. simply restart the timer to time out |
1966 | // activity. simply restart the timer to time out |
1884 | // after "after" seconds, which is the earliest time |
1967 | // after "after" seconds, which is the earliest time |
1885 | // the timeout can occur. |
1968 | // the timeout can occur. |
1886 | ev_timer_set (w, after, 0.); |
1969 | ev_timer_set (w, after, 0.); |
1887 | ev_timer_start (EV_A_ w); |
1970 | ev_timer_start (EV_A_ w); |
1888 | } |
1971 | } |
… | |
… | |
1898 | |
1981 | |
1899 | Otherwise, we now the earliest time at which the timeout would trigger, |
1982 | Otherwise, we now the earliest time at which the timeout would trigger, |
1900 | and simply start the timer with this timeout value. |
1983 | and simply start the timer with this timeout value. |
1901 | |
1984 | |
1902 | In other words, each time the callback is invoked it will check whether |
1985 | In other words, each time the callback is invoked it will check whether |
1903 | the timeout cocured. If not, it will simply reschedule itself to check |
1986 | the timeout occurred. If not, it will simply reschedule itself to check |
1904 | again at the earliest time it could time out. Rinse. Repeat. |
1987 | again at the earliest time it could time out. Rinse. Repeat. |
1905 | |
1988 | |
1906 | This scheme causes more callback invocations (about one every 60 seconds |
1989 | This scheme causes more callback invocations (about one every 60 seconds |
1907 | minus half the average time between activity), but virtually no calls to |
1990 | minus half the average time between activity), but virtually no calls to |
1908 | libev to change the timeout. |
1991 | libev to change the timeout. |
… | |
… | |
1922 | if (activity detected) |
2005 | if (activity detected) |
1923 | last_activity = ev_now (EV_A); |
2006 | last_activity = ev_now (EV_A); |
1924 | |
2007 | |
1925 | When your timeout value changes, then the timeout can be changed by simply |
2008 | When your timeout value changes, then the timeout can be changed by simply |
1926 | providing a new value, stopping the timer and calling the callback, which |
2009 | providing a new value, stopping the timer and calling the callback, which |
1927 | will agaion do the right thing (for example, time out immediately :). |
2010 | will again do the right thing (for example, time out immediately :). |
1928 | |
2011 | |
1929 | timeout = new_value; |
2012 | timeout = new_value; |
1930 | ev_timer_stop (EV_A_ &timer); |
2013 | ev_timer_stop (EV_A_ &timer); |
1931 | callback (EV_A_ &timer, 0); |
2014 | callback (EV_A_ &timer, 0); |
1932 | |
2015 | |
… | |
… | |
2015 | |
2098 | |
2016 | The relative timeouts are calculated relative to the C<ev_now ()> |
2099 | The relative timeouts are calculated relative to the C<ev_now ()> |
2017 | time. This is usually the right thing as this timestamp refers to the time |
2100 | time. This is usually the right thing as this timestamp refers to the time |
2018 | of the event triggering whatever timeout you are modifying/starting. If |
2101 | of the event triggering whatever timeout you are modifying/starting. If |
2019 | you suspect event processing to be delayed and you I<need> to base the |
2102 | you suspect event processing to be delayed and you I<need> to base the |
2020 | timeout on the current time, use something like this to adjust for this: |
2103 | timeout on the current time, use something like the following to adjust |
|
|
2104 | for it: |
2021 | |
2105 | |
2022 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
2106 | ev_timer_set (&timer, after + (ev_time () - ev_now ()), 0.); |
2023 | |
2107 | |
2024 | If the event loop is suspended for a long time, you can also force an |
2108 | If the event loop is suspended for a long time, you can also force an |
2025 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
2109 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
2026 | ()>. |
2110 | ()>, although that will push the event time of all outstanding events |
|
|
2111 | further into the future. |
2027 | |
2112 | |
2028 | =head3 The special problem of unsynchronised clocks |
2113 | =head3 The special problem of unsynchronised clocks |
2029 | |
2114 | |
2030 | Modern systems have a variety of clocks - libev itself uses the normal |
2115 | Modern systems have a variety of clocks - libev itself uses the normal |
2031 | "wall clock" clock and, if available, the monotonic clock (to avoid time |
2116 | "wall clock" clock and, if available, the monotonic clock (to avoid time |
… | |
… | |
2094 | |
2179 | |
2095 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
2180 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
2096 | |
2181 | |
2097 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
2182 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
2098 | |
2183 | |
2099 | Configure the timer to trigger after C<after> seconds. If C<repeat> |
2184 | Configure the timer to trigger after C<after> seconds (fractional and |
2100 | is C<0.>, then it will automatically be stopped once the timeout is |
2185 | negative values are supported). If C<repeat> is C<0.>, then it will |
2101 | reached. If it is positive, then the timer will automatically be |
2186 | automatically be stopped once the timeout is reached. If it is positive, |
2102 | configured to trigger again C<repeat> seconds later, again, and again, |
2187 | then the timer will automatically be configured to trigger again C<repeat> |
2103 | until stopped manually. |
2188 | seconds later, again, and again, until stopped manually. |
2104 | |
2189 | |
2105 | The timer itself will do a best-effort at avoiding drift, that is, if |
2190 | The timer itself will do a best-effort at avoiding drift, that is, if |
2106 | you configure a timer to trigger every 10 seconds, then it will normally |
2191 | you configure a timer to trigger every 10 seconds, then it will normally |
2107 | trigger at exactly 10 second intervals. If, however, your program cannot |
2192 | trigger at exactly 10 second intervals. If, however, your program cannot |
2108 | keep up with the timer (because it takes longer than those 10 seconds to |
2193 | keep up with the timer (because it takes longer than those 10 seconds to |
2109 | do stuff) the timer will not fire more than once per event loop iteration. |
2194 | do stuff) the timer will not fire more than once per event loop iteration. |
2110 | |
2195 | |
2111 | =item ev_timer_again (loop, ev_timer *) |
2196 | =item ev_timer_again (loop, ev_timer *) |
2112 | |
2197 | |
2113 | This will act as if the timer timed out and restarts it again if it is |
2198 | This will act as if the timer timed out, and restarts it again if it is |
2114 | repeating. The exact semantics are: |
2199 | repeating. It basically works like calling C<ev_timer_stop>, updating the |
|
|
2200 | timeout to the C<repeat> value and calling C<ev_timer_start>. |
2115 | |
2201 | |
|
|
2202 | The exact semantics are as in the following rules, all of which will be |
|
|
2203 | applied to the watcher: |
|
|
2204 | |
|
|
2205 | =over 4 |
|
|
2206 | |
2116 | If the timer is pending, its pending status is cleared. |
2207 | =item If the timer is pending, the pending status is always cleared. |
2117 | |
2208 | |
2118 | If the timer is started but non-repeating, stop it (as if it timed out). |
2209 | =item If the timer is started but non-repeating, stop it (as if it timed |
|
|
2210 | out, without invoking it). |
2119 | |
2211 | |
2120 | If the timer is repeating, either start it if necessary (with the |
2212 | =item If the timer is repeating, make the C<repeat> value the new timeout |
2121 | C<repeat> value), or reset the running timer to the C<repeat> value. |
2213 | and start the timer, if necessary. |
2122 | |
2214 | |
|
|
2215 | =back |
|
|
2216 | |
2123 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
2217 | This sounds a bit complicated, see L</Be smart about timeouts>, above, for a |
2124 | usage example. |
2218 | usage example. |
2125 | |
2219 | |
2126 | =item ev_tstamp ev_timer_remaining (loop, ev_timer *) |
2220 | =item ev_tstamp ev_timer_remaining (loop, ev_timer *) |
2127 | |
2221 | |
2128 | Returns the remaining time until a timer fires. If the timer is active, |
2222 | Returns the remaining time until a timer fires. If the timer is active, |
… | |
… | |
2181 | Periodic watchers are also timers of a kind, but they are very versatile |
2275 | Periodic watchers are also timers of a kind, but they are very versatile |
2182 | (and unfortunately a bit complex). |
2276 | (and unfortunately a bit complex). |
2183 | |
2277 | |
2184 | Unlike C<ev_timer>, periodic watchers are not based on real time (or |
2278 | Unlike C<ev_timer>, periodic watchers are not based on real time (or |
2185 | relative time, the physical time that passes) but on wall clock time |
2279 | relative time, the physical time that passes) but on wall clock time |
2186 | (absolute time, the thing you can read on your calender or clock). The |
2280 | (absolute time, the thing you can read on your calendar or clock). The |
2187 | difference is that wall clock time can run faster or slower than real |
2281 | difference is that wall clock time can run faster or slower than real |
2188 | time, and time jumps are not uncommon (e.g. when you adjust your |
2282 | time, and time jumps are not uncommon (e.g. when you adjust your |
2189 | wrist-watch). |
2283 | wrist-watch). |
2190 | |
2284 | |
2191 | You can tell a periodic watcher to trigger after some specific point |
2285 | You can tell a periodic watcher to trigger after some specific point |
… | |
… | |
2196 | C<ev_timer>, which would still trigger roughly 10 seconds after starting |
2290 | C<ev_timer>, which would still trigger roughly 10 seconds after starting |
2197 | it, as it uses a relative timeout). |
2291 | it, as it uses a relative timeout). |
2198 | |
2292 | |
2199 | C<ev_periodic> watchers can also be used to implement vastly more complex |
2293 | C<ev_periodic> watchers can also be used to implement vastly more complex |
2200 | timers, such as triggering an event on each "midnight, local time", or |
2294 | timers, such as triggering an event on each "midnight, local time", or |
2201 | other complicated rules. This cannot be done with C<ev_timer> watchers, as |
2295 | other complicated rules. This cannot easily be done with C<ev_timer> |
2202 | those cannot react to time jumps. |
2296 | watchers, as those cannot react to time jumps. |
2203 | |
2297 | |
2204 | As with timers, the callback is guaranteed to be invoked only when the |
2298 | As with timers, the callback is guaranteed to be invoked only when the |
2205 | point in time where it is supposed to trigger has passed. If multiple |
2299 | point in time where it is supposed to trigger has passed. If multiple |
2206 | timers become ready during the same loop iteration then the ones with |
2300 | timers become ready during the same loop iteration then the ones with |
2207 | earlier time-out values are invoked before ones with later time-out values |
2301 | earlier time-out values are invoked before ones with later time-out values |
… | |
… | |
2293 | |
2387 | |
2294 | NOTE: I<< This callback must always return a time that is higher than or |
2388 | NOTE: I<< This callback must always return a time that is higher than or |
2295 | equal to the passed C<now> value >>. |
2389 | equal to the passed C<now> value >>. |
2296 | |
2390 | |
2297 | This can be used to create very complex timers, such as a timer that |
2391 | This can be used to create very complex timers, such as a timer that |
2298 | triggers on "next midnight, local time". To do this, you would calculate the |
2392 | triggers on "next midnight, local time". To do this, you would calculate |
2299 | next midnight after C<now> and return the timestamp value for this. How |
2393 | the next midnight after C<now> and return the timestamp value for |
2300 | you do this is, again, up to you (but it is not trivial, which is the main |
2394 | this. Here is a (completely untested, no error checking) example on how to |
2301 | reason I omitted it as an example). |
2395 | do this: |
|
|
2396 | |
|
|
2397 | #include <time.h> |
|
|
2398 | |
|
|
2399 | static ev_tstamp |
|
|
2400 | my_rescheduler (ev_periodic *w, ev_tstamp now) |
|
|
2401 | { |
|
|
2402 | time_t tnow = (time_t)now; |
|
|
2403 | struct tm tm; |
|
|
2404 | localtime_r (&tnow, &tm); |
|
|
2405 | |
|
|
2406 | tm.tm_sec = tm.tm_min = tm.tm_hour = 0; // midnight current day |
|
|
2407 | ++tm.tm_mday; // midnight next day |
|
|
2408 | |
|
|
2409 | return mktime (&tm); |
|
|
2410 | } |
|
|
2411 | |
|
|
2412 | Note: this code might run into trouble on days that have more then two |
|
|
2413 | midnights (beginning and end). |
2302 | |
2414 | |
2303 | =back |
2415 | =back |
2304 | |
2416 | |
2305 | =item ev_periodic_again (loop, ev_periodic *) |
2417 | =item ev_periodic_again (loop, ev_periodic *) |
2306 | |
2418 | |
… | |
… | |
2371 | |
2483 | |
2372 | ev_periodic hourly_tick; |
2484 | ev_periodic hourly_tick; |
2373 | ev_periodic_init (&hourly_tick, clock_cb, |
2485 | ev_periodic_init (&hourly_tick, clock_cb, |
2374 | fmod (ev_now (loop), 3600.), 3600., 0); |
2486 | fmod (ev_now (loop), 3600.), 3600., 0); |
2375 | ev_periodic_start (loop, &hourly_tick); |
2487 | ev_periodic_start (loop, &hourly_tick); |
2376 | |
2488 | |
2377 | |
2489 | |
2378 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
2490 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
2379 | |
2491 | |
2380 | Signal watchers will trigger an event when the process receives a specific |
2492 | Signal watchers will trigger an event when the process receives a specific |
2381 | signal one or more times. Even though signals are very asynchronous, libev |
2493 | signal one or more times. Even though signals are very asynchronous, libev |
… | |
… | |
2391 | only within the same loop, i.e. you can watch for C<SIGINT> in your |
2503 | only within the same loop, i.e. you can watch for C<SIGINT> in your |
2392 | default loop and for C<SIGIO> in another loop, but you cannot watch for |
2504 | default loop and for C<SIGIO> in another loop, but you cannot watch for |
2393 | C<SIGINT> in both the default loop and another loop at the same time. At |
2505 | C<SIGINT> in both the default loop and another loop at the same time. At |
2394 | the moment, C<SIGCHLD> is permanently tied to the default loop. |
2506 | the moment, C<SIGCHLD> is permanently tied to the default loop. |
2395 | |
2507 | |
2396 | When the first watcher gets started will libev actually register something |
2508 | Only after the first watcher for a signal is started will libev actually |
2397 | with the kernel (thus it coexists with your own signal handlers as long as |
2509 | register something with the kernel. It thus coexists with your own signal |
2398 | you don't register any with libev for the same signal). |
2510 | handlers as long as you don't register any with libev for the same signal. |
2399 | |
2511 | |
2400 | If possible and supported, libev will install its handlers with |
2512 | If possible and supported, libev will install its handlers with |
2401 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2513 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2402 | not be unduly interrupted. If you have a problem with system calls getting |
2514 | not be unduly interrupted. If you have a problem with system calls getting |
2403 | interrupted by signals you can block all signals in an C<ev_check> watcher |
2515 | interrupted by signals you can block all signals in an C<ev_check> watcher |
… | |
… | |
2588 | |
2700 | |
2589 | =head2 C<ev_stat> - did the file attributes just change? |
2701 | =head2 C<ev_stat> - did the file attributes just change? |
2590 | |
2702 | |
2591 | This watches a file system path for attribute changes. That is, it calls |
2703 | This watches a file system path for attribute changes. That is, it calls |
2592 | C<stat> on that path in regular intervals (or when the OS says it changed) |
2704 | C<stat> on that path in regular intervals (or when the OS says it changed) |
2593 | and sees if it changed compared to the last time, invoking the callback if |
2705 | and sees if it changed compared to the last time, invoking the callback |
2594 | it did. |
2706 | if it did. Starting the watcher C<stat>'s the file, so only changes that |
|
|
2707 | happen after the watcher has been started will be reported. |
2595 | |
2708 | |
2596 | The path does not need to exist: changing from "path exists" to "path does |
2709 | The path does not need to exist: changing from "path exists" to "path does |
2597 | not exist" is a status change like any other. The condition "path does not |
2710 | not exist" is a status change like any other. The condition "path does not |
2598 | exist" (or more correctly "path cannot be stat'ed") is signified by the |
2711 | exist" (or more correctly "path cannot be stat'ed") is signified by the |
2599 | C<st_nlink> field being zero (which is otherwise always forced to be at |
2712 | C<st_nlink> field being zero (which is otherwise always forced to be at |
… | |
… | |
2829 | Apart from keeping your process non-blocking (which is a useful |
2942 | Apart from keeping your process non-blocking (which is a useful |
2830 | effect on its own sometimes), idle watchers are a good place to do |
2943 | effect on its own sometimes), idle watchers are a good place to do |
2831 | "pseudo-background processing", or delay processing stuff to after the |
2944 | "pseudo-background processing", or delay processing stuff to after the |
2832 | event loop has handled all outstanding events. |
2945 | event loop has handled all outstanding events. |
2833 | |
2946 | |
|
|
2947 | =head3 Abusing an C<ev_idle> watcher for its side-effect |
|
|
2948 | |
|
|
2949 | As long as there is at least one active idle watcher, libev will never |
|
|
2950 | sleep unnecessarily. Or in other words, it will loop as fast as possible. |
|
|
2951 | For this to work, the idle watcher doesn't need to be invoked at all - the |
|
|
2952 | lowest priority will do. |
|
|
2953 | |
|
|
2954 | This mode of operation can be useful together with an C<ev_check> watcher, |
|
|
2955 | to do something on each event loop iteration - for example to balance load |
|
|
2956 | between different connections. |
|
|
2957 | |
|
|
2958 | See L</Abusing an ev_check watcher for its side-effect> for a longer |
|
|
2959 | example. |
|
|
2960 | |
2834 | =head3 Watcher-Specific Functions and Data Members |
2961 | =head3 Watcher-Specific Functions and Data Members |
2835 | |
2962 | |
2836 | =over 4 |
2963 | =over 4 |
2837 | |
2964 | |
2838 | =item ev_idle_init (ev_idle *, callback) |
2965 | =item ev_idle_init (ev_idle *, callback) |
… | |
… | |
2849 | callback, free it. Also, use no error checking, as usual. |
2976 | callback, free it. Also, use no error checking, as usual. |
2850 | |
2977 | |
2851 | static void |
2978 | static void |
2852 | idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
2979 | idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
2853 | { |
2980 | { |
|
|
2981 | // stop the watcher |
|
|
2982 | ev_idle_stop (loop, w); |
|
|
2983 | |
|
|
2984 | // now we can free it |
2854 | free (w); |
2985 | free (w); |
|
|
2986 | |
2855 | // now do something you wanted to do when the program has |
2987 | // now do something you wanted to do when the program has |
2856 | // no longer anything immediate to do. |
2988 | // no longer anything immediate to do. |
2857 | } |
2989 | } |
2858 | |
2990 | |
2859 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
2991 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
… | |
… | |
2861 | ev_idle_start (loop, idle_watcher); |
2993 | ev_idle_start (loop, idle_watcher); |
2862 | |
2994 | |
2863 | |
2995 | |
2864 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
2996 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
2865 | |
2997 | |
2866 | Prepare and check watchers are usually (but not always) used in pairs: |
2998 | Prepare and check watchers are often (but not always) used in pairs: |
2867 | prepare watchers get invoked before the process blocks and check watchers |
2999 | prepare watchers get invoked before the process blocks and check watchers |
2868 | afterwards. |
3000 | afterwards. |
2869 | |
3001 | |
2870 | You I<must not> call C<ev_run> or similar functions that enter |
3002 | You I<must not> call C<ev_run> (or similar functions that enter the |
2871 | the current event loop from either C<ev_prepare> or C<ev_check> |
3003 | current event loop) or C<ev_loop_fork> from either C<ev_prepare> or |
2872 | watchers. Other loops than the current one are fine, however. The |
3004 | C<ev_check> watchers. Other loops than the current one are fine, |
2873 | rationale behind this is that you do not need to check for recursion in |
3005 | however. The rationale behind this is that you do not need to check |
2874 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
3006 | for recursion in those watchers, i.e. the sequence will always be |
2875 | C<ev_check> so if you have one watcher of each kind they will always be |
3007 | C<ev_prepare>, blocking, C<ev_check> so if you have one watcher of each |
2876 | called in pairs bracketing the blocking call. |
3008 | kind they will always be called in pairs bracketing the blocking call. |
2877 | |
3009 | |
2878 | Their main purpose is to integrate other event mechanisms into libev and |
3010 | Their main purpose is to integrate other event mechanisms into libev and |
2879 | their use is somewhat advanced. They could be used, for example, to track |
3011 | their use is somewhat advanced. They could be used, for example, to track |
2880 | variable changes, implement your own watchers, integrate net-snmp or a |
3012 | variable changes, implement your own watchers, integrate net-snmp or a |
2881 | coroutine library and lots more. They are also occasionally useful if |
3013 | coroutine library and lots more. They are also occasionally useful if |
… | |
… | |
2899 | with priority higher than or equal to the event loop and one coroutine |
3031 | with priority higher than or equal to the event loop and one coroutine |
2900 | of lower priority, but only once, using idle watchers to keep the event |
3032 | of lower priority, but only once, using idle watchers to keep the event |
2901 | loop from blocking if lower-priority coroutines are active, thus mapping |
3033 | loop from blocking if lower-priority coroutines are active, thus mapping |
2902 | low-priority coroutines to idle/background tasks). |
3034 | low-priority coroutines to idle/background tasks). |
2903 | |
3035 | |
2904 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
3036 | When used for this purpose, it is recommended to give C<ev_check> watchers |
2905 | priority, to ensure that they are being run before any other watchers |
3037 | highest (C<EV_MAXPRI>) priority, to ensure that they are being run before |
2906 | after the poll (this doesn't matter for C<ev_prepare> watchers). |
3038 | any other watchers after the poll (this doesn't matter for C<ev_prepare> |
|
|
3039 | watchers). |
2907 | |
3040 | |
2908 | Also, C<ev_check> watchers (and C<ev_prepare> watchers, too) should not |
3041 | Also, C<ev_check> watchers (and C<ev_prepare> watchers, too) should not |
2909 | activate ("feed") events into libev. While libev fully supports this, they |
3042 | activate ("feed") events into libev. While libev fully supports this, they |
2910 | might get executed before other C<ev_check> watchers did their job. As |
3043 | might get executed before other C<ev_check> watchers did their job. As |
2911 | C<ev_check> watchers are often used to embed other (non-libev) event |
3044 | C<ev_check> watchers are often used to embed other (non-libev) event |
2912 | loops those other event loops might be in an unusable state until their |
3045 | loops those other event loops might be in an unusable state until their |
2913 | C<ev_check> watcher ran (always remind yourself to coexist peacefully with |
3046 | C<ev_check> watcher ran (always remind yourself to coexist peacefully with |
2914 | others). |
3047 | others). |
|
|
3048 | |
|
|
3049 | =head3 Abusing an C<ev_check> watcher for its side-effect |
|
|
3050 | |
|
|
3051 | C<ev_check> (and less often also C<ev_prepare>) watchers can also be |
|
|
3052 | useful because they are called once per event loop iteration. For |
|
|
3053 | example, if you want to handle a large number of connections fairly, you |
|
|
3054 | normally only do a bit of work for each active connection, and if there |
|
|
3055 | is more work to do, you wait for the next event loop iteration, so other |
|
|
3056 | connections have a chance of making progress. |
|
|
3057 | |
|
|
3058 | Using an C<ev_check> watcher is almost enough: it will be called on the |
|
|
3059 | next event loop iteration. However, that isn't as soon as possible - |
|
|
3060 | without external events, your C<ev_check> watcher will not be invoked. |
|
|
3061 | |
|
|
3062 | This is where C<ev_idle> watchers come in handy - all you need is a |
|
|
3063 | single global idle watcher that is active as long as you have one active |
|
|
3064 | C<ev_check> watcher. The C<ev_idle> watcher makes sure the event loop |
|
|
3065 | will not sleep, and the C<ev_check> watcher makes sure a callback gets |
|
|
3066 | invoked. Neither watcher alone can do that. |
2915 | |
3067 | |
2916 | =head3 Watcher-Specific Functions and Data Members |
3068 | =head3 Watcher-Specific Functions and Data Members |
2917 | |
3069 | |
2918 | =over 4 |
3070 | =over 4 |
2919 | |
3071 | |
… | |
… | |
3120 | |
3272 | |
3121 | =over 4 |
3273 | =over 4 |
3122 | |
3274 | |
3123 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
3275 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
3124 | |
3276 | |
3125 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
3277 | =item ev_embed_set (ev_embed *, struct ev_loop *embedded_loop) |
3126 | |
3278 | |
3127 | Configures the watcher to embed the given loop, which must be |
3279 | Configures the watcher to embed the given loop, which must be |
3128 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
3280 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
3129 | invoked automatically, otherwise it is the responsibility of the callback |
3281 | invoked automatically, otherwise it is the responsibility of the callback |
3130 | to invoke it (it will continue to be called until the sweep has been done, |
3282 | to invoke it (it will continue to be called until the sweep has been done, |
… | |
… | |
3151 | used). |
3303 | used). |
3152 | |
3304 | |
3153 | struct ev_loop *loop_hi = ev_default_init (0); |
3305 | struct ev_loop *loop_hi = ev_default_init (0); |
3154 | struct ev_loop *loop_lo = 0; |
3306 | struct ev_loop *loop_lo = 0; |
3155 | ev_embed embed; |
3307 | ev_embed embed; |
3156 | |
3308 | |
3157 | // see if there is a chance of getting one that works |
3309 | // see if there is a chance of getting one that works |
3158 | // (remember that a flags value of 0 means autodetection) |
3310 | // (remember that a flags value of 0 means autodetection) |
3159 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3311 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3160 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3312 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3161 | : 0; |
3313 | : 0; |
… | |
… | |
3175 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
3327 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
3176 | |
3328 | |
3177 | struct ev_loop *loop = ev_default_init (0); |
3329 | struct ev_loop *loop = ev_default_init (0); |
3178 | struct ev_loop *loop_socket = 0; |
3330 | struct ev_loop *loop_socket = 0; |
3179 | ev_embed embed; |
3331 | ev_embed embed; |
3180 | |
3332 | |
3181 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3333 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3182 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3334 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3183 | { |
3335 | { |
3184 | ev_embed_init (&embed, 0, loop_socket); |
3336 | ev_embed_init (&embed, 0, loop_socket); |
3185 | ev_embed_start (loop, &embed); |
3337 | ev_embed_start (loop, &embed); |
… | |
… | |
3193 | |
3345 | |
3194 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
3346 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
3195 | |
3347 | |
3196 | Fork watchers are called when a C<fork ()> was detected (usually because |
3348 | Fork watchers are called when a C<fork ()> was detected (usually because |
3197 | whoever is a good citizen cared to tell libev about it by calling |
3349 | whoever is a good citizen cared to tell libev about it by calling |
3198 | C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the |
3350 | C<ev_loop_fork>). The invocation is done before the event loop blocks next |
3199 | event loop blocks next and before C<ev_check> watchers are being called, |
3351 | and before C<ev_check> watchers are being called, and only in the child |
3200 | and only in the child after the fork. If whoever good citizen calling |
3352 | after the fork. If whoever good citizen calling C<ev_default_fork> cheats |
3201 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
3353 | and calls it in the wrong process, the fork handlers will be invoked, too, |
3202 | handlers will be invoked, too, of course. |
3354 | of course. |
3203 | |
3355 | |
3204 | =head3 The special problem of life after fork - how is it possible? |
3356 | =head3 The special problem of life after fork - how is it possible? |
3205 | |
3357 | |
3206 | Most uses of C<fork()> consist of forking, then some simple calls to set |
3358 | Most uses of C<fork ()> consist of forking, then some simple calls to set |
3207 | up/change the process environment, followed by a call to C<exec()>. This |
3359 | up/change the process environment, followed by a call to C<exec()>. This |
3208 | sequence should be handled by libev without any problems. |
3360 | sequence should be handled by libev without any problems. |
3209 | |
3361 | |
3210 | This changes when the application actually wants to do event handling |
3362 | This changes when the application actually wants to do event handling |
3211 | in the child, or both parent in child, in effect "continuing" after the |
3363 | in the child, or both parent in child, in effect "continuing" after the |
… | |
… | |
3300 | it by calling C<ev_async_send>, which is thread- and signal safe. |
3452 | it by calling C<ev_async_send>, which is thread- and signal safe. |
3301 | |
3453 | |
3302 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3454 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3303 | too, are asynchronous in nature, and signals, too, will be compressed |
3455 | too, are asynchronous in nature, and signals, too, will be compressed |
3304 | (i.e. the number of callback invocations may be less than the number of |
3456 | (i.e. the number of callback invocations may be less than the number of |
3305 | C<ev_async_sent> calls). In fact, you could use signal watchers as a kind |
3457 | C<ev_async_send> calls). In fact, you could use signal watchers as a kind |
3306 | of "global async watchers" by using a watcher on an otherwise unused |
3458 | of "global async watchers" by using a watcher on an otherwise unused |
3307 | signal, and C<ev_feed_signal> to signal this watcher from another thread, |
3459 | signal, and C<ev_feed_signal> to signal this watcher from another thread, |
3308 | even without knowing which loop owns the signal. |
3460 | even without knowing which loop owns the signal. |
3309 | |
3461 | |
3310 | =head3 Queueing |
3462 | =head3 Queueing |
… | |
… | |
3449 | |
3601 | |
3450 | There are some other functions of possible interest. Described. Here. Now. |
3602 | There are some other functions of possible interest. Described. Here. Now. |
3451 | |
3603 | |
3452 | =over 4 |
3604 | =over 4 |
3453 | |
3605 | |
3454 | =item ev_once (loop, int fd, int events, ev_tstamp timeout, callback) |
3606 | =item ev_once (loop, int fd, int events, ev_tstamp timeout, callback, arg) |
3455 | |
3607 | |
3456 | This function combines a simple timer and an I/O watcher, calls your |
3608 | This function combines a simple timer and an I/O watcher, calls your |
3457 | callback on whichever event happens first and automatically stops both |
3609 | callback on whichever event happens first and automatically stops both |
3458 | watchers. This is useful if you want to wait for a single event on an fd |
3610 | watchers. This is useful if you want to wait for a single event on an fd |
3459 | or timeout without having to allocate/configure/start/stop/free one or |
3611 | or timeout without having to allocate/configure/start/stop/free one or |
… | |
… | |
3601 | already been invoked. |
3753 | already been invoked. |
3602 | |
3754 | |
3603 | A common way around all these issues is to make sure that |
3755 | A common way around all these issues is to make sure that |
3604 | C<start_new_request> I<always> returns before the callback is invoked. If |
3756 | C<start_new_request> I<always> returns before the callback is invoked. If |
3605 | C<start_new_request> immediately knows the result, it can artificially |
3757 | C<start_new_request> immediately knows the result, it can artificially |
3606 | delay invoking the callback by e.g. using a C<prepare> or C<idle> watcher |
3758 | delay invoking the callback by using a C<prepare> or C<idle> watcher for |
3607 | for example, or more sneakily, by reusing an existing (stopped) watcher |
3759 | example, or more sneakily, by reusing an existing (stopped) watcher and |
3608 | and pushing it into the pending queue: |
3760 | pushing it into the pending queue: |
3609 | |
3761 | |
3610 | ev_set_cb (watcher, callback); |
3762 | ev_set_cb (watcher, callback); |
3611 | ev_feed_event (EV_A_ watcher, 0); |
3763 | ev_feed_event (EV_A_ watcher, 0); |
3612 | |
3764 | |
3613 | This way, C<start_new_request> can safely return before the callback is |
3765 | This way, C<start_new_request> can safely return before the callback is |
… | |
… | |
3621 | |
3773 | |
3622 | This brings the problem of exiting - a callback might want to finish the |
3774 | This brings the problem of exiting - a callback might want to finish the |
3623 | main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but |
3775 | main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but |
3624 | a modal "Are you sure?" dialog is still waiting), or just the nested one |
3776 | a modal "Are you sure?" dialog is still waiting), or just the nested one |
3625 | and not the main one (e.g. user clocked "Ok" in a modal dialog), or some |
3777 | and not the main one (e.g. user clocked "Ok" in a modal dialog), or some |
3626 | other combination: In these cases, C<ev_break> will not work alone. |
3778 | other combination: In these cases, a simple C<ev_break> will not work. |
3627 | |
3779 | |
3628 | The solution is to maintain "break this loop" variable for each C<ev_run> |
3780 | The solution is to maintain "break this loop" variable for each C<ev_run> |
3629 | invocation, and use a loop around C<ev_run> until the condition is |
3781 | invocation, and use a loop around C<ev_run> until the condition is |
3630 | triggered, using C<EVRUN_ONCE>: |
3782 | triggered, using C<EVRUN_ONCE>: |
3631 | |
3783 | |
… | |
… | |
3633 | int exit_main_loop = 0; |
3785 | int exit_main_loop = 0; |
3634 | |
3786 | |
3635 | while (!exit_main_loop) |
3787 | while (!exit_main_loop) |
3636 | ev_run (EV_DEFAULT_ EVRUN_ONCE); |
3788 | ev_run (EV_DEFAULT_ EVRUN_ONCE); |
3637 | |
3789 | |
3638 | // in a model watcher |
3790 | // in a modal watcher |
3639 | int exit_nested_loop = 0; |
3791 | int exit_nested_loop = 0; |
3640 | |
3792 | |
3641 | while (!exit_nested_loop) |
3793 | while (!exit_nested_loop) |
3642 | ev_run (EV_A_ EVRUN_ONCE); |
3794 | ev_run (EV_A_ EVRUN_ONCE); |
3643 | |
3795 | |
… | |
… | |
3817 | called): |
3969 | called): |
3818 | |
3970 | |
3819 | void |
3971 | void |
3820 | wait_for_event (ev_watcher *w) |
3972 | wait_for_event (ev_watcher *w) |
3821 | { |
3973 | { |
3822 | ev_cb_set (w) = current_coro; |
3974 | ev_set_cb (w, current_coro); |
3823 | switch_to (libev_coro); |
3975 | switch_to (libev_coro); |
3824 | } |
3976 | } |
3825 | |
3977 | |
3826 | That basically suspends the coroutine inside C<wait_for_event> and |
3978 | That basically suspends the coroutine inside C<wait_for_event> and |
3827 | continues the libev coroutine, which, when appropriate, switches back to |
3979 | continues the libev coroutine, which, when appropriate, switches back to |
3828 | this or any other coroutine. I am sure if you sue this your own :) |
3980 | this or any other coroutine. |
3829 | |
3981 | |
3830 | You can do similar tricks if you have, say, threads with an event queue - |
3982 | You can do similar tricks if you have, say, threads with an event queue - |
3831 | instead of storing a coroutine, you store the queue object and instead of |
3983 | instead of storing a coroutine, you store the queue object and instead of |
3832 | switching to a coroutine, you push the watcher onto the queue and notify |
3984 | switching to a coroutine, you push the watcher onto the queue and notify |
3833 | any waiters. |
3985 | any waiters. |
3834 | |
3986 | |
3835 | To embed libev, see L<EMBEDDING>, but in short, it's easiest to create two |
3987 | To embed libev, see L</EMBEDDING>, but in short, it's easiest to create two |
3836 | files, F<my_ev.h> and F<my_ev.c> that include the respective libev files: |
3988 | files, F<my_ev.h> and F<my_ev.c> that include the respective libev files: |
3837 | |
3989 | |
3838 | // my_ev.h |
3990 | // my_ev.h |
3839 | #define EV_CB_DECLARE(type) struct my_coro *cb; |
3991 | #define EV_CB_DECLARE(type) struct my_coro *cb; |
3840 | #define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb); |
3992 | #define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb) |
3841 | #include "../libev/ev.h" |
3993 | #include "../libev/ev.h" |
3842 | |
3994 | |
3843 | // my_ev.c |
3995 | // my_ev.c |
3844 | #define EV_H "my_ev.h" |
3996 | #define EV_H "my_ev.h" |
3845 | #include "../libev/ev.c" |
3997 | #include "../libev/ev.c" |
… | |
… | |
3884 | |
4036 | |
3885 | =back |
4037 | =back |
3886 | |
4038 | |
3887 | =head1 C++ SUPPORT |
4039 | =head1 C++ SUPPORT |
3888 | |
4040 | |
|
|
4041 | =head2 C API |
|
|
4042 | |
|
|
4043 | The normal C API should work fine when used from C++: both ev.h and the |
|
|
4044 | libev sources can be compiled as C++. Therefore, code that uses the C API |
|
|
4045 | will work fine. |
|
|
4046 | |
|
|
4047 | Proper exception specifications might have to be added to callbacks passed |
|
|
4048 | to libev: exceptions may be thrown only from watcher callbacks, all other |
|
|
4049 | callbacks (allocator, syserr, loop acquire/release and periodic reschedule |
|
|
4050 | callbacks) must not throw exceptions, and might need a C<noexcept> |
|
|
4051 | specification. If you have code that needs to be compiled as both C and |
|
|
4052 | C++ you can use the C<EV_NOEXCEPT> macro for this: |
|
|
4053 | |
|
|
4054 | static void |
|
|
4055 | fatal_error (const char *msg) EV_NOEXCEPT |
|
|
4056 | { |
|
|
4057 | perror (msg); |
|
|
4058 | abort (); |
|
|
4059 | } |
|
|
4060 | |
|
|
4061 | ... |
|
|
4062 | ev_set_syserr_cb (fatal_error); |
|
|
4063 | |
|
|
4064 | The only API functions that can currently throw exceptions are C<ev_run>, |
|
|
4065 | C<ev_invoke>, C<ev_invoke_pending> and C<ev_loop_destroy> (the latter |
|
|
4066 | because it runs cleanup watchers). |
|
|
4067 | |
|
|
4068 | Throwing exceptions in watcher callbacks is only supported if libev itself |
|
|
4069 | is compiled with a C++ compiler or your C and C++ environments allow |
|
|
4070 | throwing exceptions through C libraries (most do). |
|
|
4071 | |
|
|
4072 | =head2 C++ API |
|
|
4073 | |
3889 | Libev comes with some simplistic wrapper classes for C++ that mainly allow |
4074 | Libev comes with some simplistic wrapper classes for C++ that mainly allow |
3890 | you to use some convenience methods to start/stop watchers and also change |
4075 | you to use some convenience methods to start/stop watchers and also change |
3891 | the callback model to a model using method callbacks on objects. |
4076 | the callback model to a model using method callbacks on objects. |
3892 | |
4077 | |
3893 | To use it, |
4078 | To use it, |
3894 | |
4079 | |
3895 | #include <ev++.h> |
4080 | #include <ev++.h> |
3896 | |
4081 | |
3897 | This automatically includes F<ev.h> and puts all of its definitions (many |
4082 | This automatically includes F<ev.h> and puts all of its definitions (many |
3898 | of them macros) into the global namespace. All C++ specific things are |
4083 | of them macros) into the global namespace. All C++ specific things are |
3899 | put into the C<ev> namespace. It should support all the same embedding |
4084 | put into the C<ev> namespace. It should support all the same embedding |
… | |
… | |
3908 | with C<operator ()> can be used as callbacks. Other types should be easy |
4093 | with C<operator ()> can be used as callbacks. Other types should be easy |
3909 | to add as long as they only need one additional pointer for context. If |
4094 | to add as long as they only need one additional pointer for context. If |
3910 | you need support for other types of functors please contact the author |
4095 | you need support for other types of functors please contact the author |
3911 | (preferably after implementing it). |
4096 | (preferably after implementing it). |
3912 | |
4097 | |
|
|
4098 | For all this to work, your C++ compiler either has to use the same calling |
|
|
4099 | conventions as your C compiler (for static member functions), or you have |
|
|
4100 | to embed libev and compile libev itself as C++. |
|
|
4101 | |
3913 | Here is a list of things available in the C<ev> namespace: |
4102 | Here is a list of things available in the C<ev> namespace: |
3914 | |
4103 | |
3915 | =over 4 |
4104 | =over 4 |
3916 | |
4105 | |
3917 | =item C<ev::READ>, C<ev::WRITE> etc. |
4106 | =item C<ev::READ>, C<ev::WRITE> etc. |
… | |
… | |
3926 | =item C<ev::io>, C<ev::timer>, C<ev::periodic>, C<ev::idle>, C<ev::sig> etc. |
4115 | =item C<ev::io>, C<ev::timer>, C<ev::periodic>, C<ev::idle>, C<ev::sig> etc. |
3927 | |
4116 | |
3928 | For each C<ev_TYPE> watcher in F<ev.h> there is a corresponding class of |
4117 | For each C<ev_TYPE> watcher in F<ev.h> there is a corresponding class of |
3929 | the same name in the C<ev> namespace, with the exception of C<ev_signal> |
4118 | the same name in the C<ev> namespace, with the exception of C<ev_signal> |
3930 | which is called C<ev::sig> to avoid clashes with the C<signal> macro |
4119 | which is called C<ev::sig> to avoid clashes with the C<signal> macro |
3931 | defines by many implementations. |
4120 | defined by many implementations. |
3932 | |
4121 | |
3933 | All of those classes have these methods: |
4122 | All of those classes have these methods: |
3934 | |
4123 | |
3935 | =over 4 |
4124 | =over 4 |
3936 | |
4125 | |
… | |
… | |
3998 | void operator() (ev::io &w, int revents) |
4187 | void operator() (ev::io &w, int revents) |
3999 | { |
4188 | { |
4000 | ... |
4189 | ... |
4001 | } |
4190 | } |
4002 | } |
4191 | } |
4003 | |
4192 | |
4004 | myfunctor f; |
4193 | myfunctor f; |
4005 | |
4194 | |
4006 | ev::io w; |
4195 | ev::io w; |
4007 | w.set (&f); |
4196 | w.set (&f); |
4008 | |
4197 | |
… | |
… | |
4026 | Associates a different C<struct ev_loop> with this watcher. You can only |
4215 | Associates a different C<struct ev_loop> with this watcher. You can only |
4027 | do this when the watcher is inactive (and not pending either). |
4216 | do this when the watcher is inactive (and not pending either). |
4028 | |
4217 | |
4029 | =item w->set ([arguments]) |
4218 | =item w->set ([arguments]) |
4030 | |
4219 | |
4031 | Basically the same as C<ev_TYPE_set>, with the same arguments. Either this |
4220 | Basically the same as C<ev_TYPE_set> (except for C<ev::embed> watchers>), |
4032 | method or a suitable start method must be called at least once. Unlike the |
4221 | with the same arguments. Either this method or a suitable start method |
4033 | C counterpart, an active watcher gets automatically stopped and restarted |
4222 | must be called at least once. Unlike the C counterpart, an active watcher |
4034 | when reconfiguring it with this method. |
4223 | gets automatically stopped and restarted when reconfiguring it with this |
|
|
4224 | method. |
|
|
4225 | |
|
|
4226 | For C<ev::embed> watchers this method is called C<set_embed>, to avoid |
|
|
4227 | clashing with the C<set (loop)> method. |
4035 | |
4228 | |
4036 | =item w->start () |
4229 | =item w->start () |
4037 | |
4230 | |
4038 | Starts the watcher. Note that there is no C<loop> argument, as the |
4231 | Starts the watcher. Note that there is no C<loop> argument, as the |
4039 | constructor already stores the event loop. |
4232 | constructor already stores the event loop. |
… | |
… | |
4143 | |
4336 | |
4144 | Brian Maher has written a partial interface to libev for lua (at the |
4337 | Brian Maher has written a partial interface to libev for lua (at the |
4145 | time of this writing, only C<ev_io> and C<ev_timer>), to be found at |
4338 | time of this writing, only C<ev_io> and C<ev_timer>), to be found at |
4146 | L<http://github.com/brimworks/lua-ev>. |
4339 | L<http://github.com/brimworks/lua-ev>. |
4147 | |
4340 | |
|
|
4341 | =item Javascript |
|
|
4342 | |
|
|
4343 | Node.js (L<http://nodejs.org>) uses libev as the underlying event library. |
|
|
4344 | |
|
|
4345 | =item Others |
|
|
4346 | |
|
|
4347 | There are others, and I stopped counting. |
|
|
4348 | |
4148 | =back |
4349 | =back |
4149 | |
4350 | |
4150 | |
4351 | |
4151 | =head1 MACRO MAGIC |
4352 | =head1 MACRO MAGIC |
4152 | |
4353 | |
… | |
… | |
4269 | ev_vars.h |
4470 | ev_vars.h |
4270 | ev_wrap.h |
4471 | ev_wrap.h |
4271 | |
4472 | |
4272 | ev_win32.c required on win32 platforms only |
4473 | ev_win32.c required on win32 platforms only |
4273 | |
4474 | |
4274 | ev_select.c only when select backend is enabled (which is enabled by default) |
4475 | ev_select.c only when select backend is enabled |
4275 | ev_poll.c only when poll backend is enabled (disabled by default) |
4476 | ev_poll.c only when poll backend is enabled |
4276 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
4477 | ev_epoll.c only when the epoll backend is enabled |
|
|
4478 | ev_linuxaio.c only when the linux aio backend is enabled |
4277 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
4479 | ev_kqueue.c only when the kqueue backend is enabled |
4278 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
4480 | ev_port.c only when the solaris port backend is enabled |
4279 | |
4481 | |
4280 | F<ev.c> includes the backend files directly when enabled, so you only need |
4482 | F<ev.c> includes the backend files directly when enabled, so you only need |
4281 | to compile this single file. |
4483 | to compile this single file. |
4282 | |
4484 | |
4283 | =head3 LIBEVENT COMPATIBILITY API |
4485 | =head3 LIBEVENT COMPATIBILITY API |
… | |
… | |
4451 | If programs implement their own fd to handle mapping on win32, then this |
4653 | If programs implement their own fd to handle mapping on win32, then this |
4452 | macro can be used to override the C<close> function, useful to unregister |
4654 | macro can be used to override the C<close> function, useful to unregister |
4453 | file descriptors again. Note that the replacement function has to close |
4655 | file descriptors again. Note that the replacement function has to close |
4454 | the underlying OS handle. |
4656 | the underlying OS handle. |
4455 | |
4657 | |
|
|
4658 | =item EV_USE_WSASOCKET |
|
|
4659 | |
|
|
4660 | If defined to be C<1>, libev will use C<WSASocket> to create its internal |
|
|
4661 | communication socket, which works better in some environments. Otherwise, |
|
|
4662 | the normal C<socket> function will be used, which works better in other |
|
|
4663 | environments. |
|
|
4664 | |
4456 | =item EV_USE_POLL |
4665 | =item EV_USE_POLL |
4457 | |
4666 | |
4458 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
4667 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
4459 | backend. Otherwise it will be enabled on non-win32 platforms. It |
4668 | backend. Otherwise it will be enabled on non-win32 platforms. It |
4460 | takes precedence over select. |
4669 | takes precedence over select. |
… | |
… | |
4464 | If defined to be C<1>, libev will compile in support for the Linux |
4673 | If defined to be C<1>, libev will compile in support for the Linux |
4465 | C<epoll>(7) backend. Its availability will be detected at runtime, |
4674 | C<epoll>(7) backend. Its availability will be detected at runtime, |
4466 | otherwise another method will be used as fallback. This is the preferred |
4675 | otherwise another method will be used as fallback. This is the preferred |
4467 | backend for GNU/Linux systems. If undefined, it will be enabled if the |
4676 | backend for GNU/Linux systems. If undefined, it will be enabled if the |
4468 | headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
4677 | headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
|
|
4678 | |
|
|
4679 | =item EV_USE_LINUXAIO |
|
|
4680 | |
|
|
4681 | If defined to be C<1>, libev will compile in support for the Linux |
|
|
4682 | aio backend. Due to it's currenbt limitations it has to be requested |
|
|
4683 | explicitly. If undefined, it will be enabled on linux, otherwise |
|
|
4684 | disabled. |
4469 | |
4685 | |
4470 | =item EV_USE_KQUEUE |
4686 | =item EV_USE_KQUEUE |
4471 | |
4687 | |
4472 | If defined to be C<1>, libev will compile in support for the BSD style |
4688 | If defined to be C<1>, libev will compile in support for the BSD style |
4473 | C<kqueue>(2) backend. Its actual availability will be detected at runtime, |
4689 | C<kqueue>(2) backend. Its actual availability will be detected at runtime, |
… | |
… | |
4495 | If defined to be C<1>, libev will compile in support for the Linux inotify |
4711 | If defined to be C<1>, libev will compile in support for the Linux inotify |
4496 | interface to speed up C<ev_stat> watchers. Its actual availability will |
4712 | interface to speed up C<ev_stat> watchers. Its actual availability will |
4497 | be detected at runtime. If undefined, it will be enabled if the headers |
4713 | be detected at runtime. If undefined, it will be enabled if the headers |
4498 | indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
4714 | indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
4499 | |
4715 | |
|
|
4716 | =item EV_NO_SMP |
|
|
4717 | |
|
|
4718 | If defined to be C<1>, libev will assume that memory is always coherent |
|
|
4719 | between threads, that is, threads can be used, but threads never run on |
|
|
4720 | different cpus (or different cpu cores). This reduces dependencies |
|
|
4721 | and makes libev faster. |
|
|
4722 | |
|
|
4723 | =item EV_NO_THREADS |
|
|
4724 | |
|
|
4725 | If defined to be C<1>, libev will assume that it will never be called from |
|
|
4726 | different threads (that includes signal handlers), which is a stronger |
|
|
4727 | assumption than C<EV_NO_SMP>, above. This reduces dependencies and makes |
|
|
4728 | libev faster. |
|
|
4729 | |
4500 | =item EV_ATOMIC_T |
4730 | =item EV_ATOMIC_T |
4501 | |
4731 | |
4502 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
4732 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
4503 | access is atomic and serialised with respect to other threads or signal |
4733 | access is atomic with respect to other threads or signal contexts. No |
4504 | contexts. No such type is easily found in the C language, so you can |
4734 | such type is easily found in the C language, so you can provide your own |
4505 | provide your own type that you know is safe for your purposes. It is used |
4735 | type that you know is safe for your purposes. It is used both for signal |
4506 | both for signal handler "locking" as well as for signal and thread safety |
4736 | handler "locking" as well as for signal and thread safety in C<ev_async> |
4507 | in C<ev_async> watchers. |
4737 | watchers. |
4508 | |
4738 | |
4509 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
4739 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
4510 | (from F<signal.h>), which is usually good enough on most platforms, |
4740 | (from F<signal.h>), which is usually good enough on most platforms. |
4511 | although strictly speaking using a type that also implies a memory fence |
|
|
4512 | is required. |
|
|
4513 | |
4741 | |
4514 | =item EV_H (h) |
4742 | =item EV_H (h) |
4515 | |
4743 | |
4516 | The name of the F<ev.h> header file used to include it. The default if |
4744 | The name of the F<ev.h> header file used to include it. The default if |
4517 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
4745 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
… | |
… | |
4590 | #define EV_USE_POLL 1 |
4818 | #define EV_USE_POLL 1 |
4591 | #define EV_CHILD_ENABLE 1 |
4819 | #define EV_CHILD_ENABLE 1 |
4592 | #define EV_ASYNC_ENABLE 1 |
4820 | #define EV_ASYNC_ENABLE 1 |
4593 | |
4821 | |
4594 | The actual value is a bitset, it can be a combination of the following |
4822 | The actual value is a bitset, it can be a combination of the following |
4595 | values: |
4823 | values (by default, all of these are enabled): |
4596 | |
4824 | |
4597 | =over 4 |
4825 | =over 4 |
4598 | |
4826 | |
4599 | =item C<1> - faster/larger code |
4827 | =item C<1> - faster/larger code |
4600 | |
4828 | |
… | |
… | |
4604 | code size by roughly 30% on amd64). |
4832 | code size by roughly 30% on amd64). |
4605 | |
4833 | |
4606 | When optimising for size, use of compiler flags such as C<-Os> with |
4834 | When optimising for size, use of compiler flags such as C<-Os> with |
4607 | gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of |
4835 | gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of |
4608 | assertions. |
4836 | assertions. |
|
|
4837 | |
|
|
4838 | The default is off when C<__OPTIMIZE_SIZE__> is defined by your compiler |
|
|
4839 | (e.g. gcc with C<-Os>). |
4609 | |
4840 | |
4610 | =item C<2> - faster/larger data structures |
4841 | =item C<2> - faster/larger data structures |
4611 | |
4842 | |
4612 | Replaces the small 2-heap for timer management by a faster 4-heap, larger |
4843 | Replaces the small 2-heap for timer management by a faster 4-heap, larger |
4613 | hash table sizes and so on. This will usually further increase code size |
4844 | hash table sizes and so on. This will usually further increase code size |
4614 | and can additionally have an effect on the size of data structures at |
4845 | and can additionally have an effect on the size of data structures at |
4615 | runtime. |
4846 | runtime. |
|
|
4847 | |
|
|
4848 | The default is off when C<__OPTIMIZE_SIZE__> is defined by your compiler |
|
|
4849 | (e.g. gcc with C<-Os>). |
4616 | |
4850 | |
4617 | =item C<4> - full API configuration |
4851 | =item C<4> - full API configuration |
4618 | |
4852 | |
4619 | This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and |
4853 | This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and |
4620 | enables multiplicity (C<EV_MULTIPLICITY>=1). |
4854 | enables multiplicity (C<EV_MULTIPLICITY>=1). |
… | |
… | |
4662 | when you embed libev, only want to use libev functions in a single file, |
4896 | when you embed libev, only want to use libev functions in a single file, |
4663 | and do not want its identifiers to be visible. |
4897 | and do not want its identifiers to be visible. |
4664 | |
4898 | |
4665 | To use this, define C<EV_API_STATIC> and include F<ev.c> in the file that |
4899 | To use this, define C<EV_API_STATIC> and include F<ev.c> in the file that |
4666 | wants to use libev. |
4900 | wants to use libev. |
|
|
4901 | |
|
|
4902 | This option only works when libev is compiled with a C compiler, as C++ |
|
|
4903 | doesn't support the required declaration syntax. |
4667 | |
4904 | |
4668 | =item EV_AVOID_STDIO |
4905 | =item EV_AVOID_STDIO |
4669 | |
4906 | |
4670 | If this is set to C<1> at compiletime, then libev will avoid using stdio |
4907 | If this is set to C<1> at compiletime, then libev will avoid using stdio |
4671 | functions (printf, scanf, perror etc.). This will increase the code size |
4908 | functions (printf, scanf, perror etc.). This will increase the code size |
… | |
… | |
4876 | default loop and triggering an C<ev_async> watcher from the default loop |
5113 | default loop and triggering an C<ev_async> watcher from the default loop |
4877 | watcher callback into the event loop interested in the signal. |
5114 | watcher callback into the event loop interested in the signal. |
4878 | |
5115 | |
4879 | =back |
5116 | =back |
4880 | |
5117 | |
4881 | See also L<THREAD LOCKING EXAMPLE>. |
5118 | See also L</THREAD LOCKING EXAMPLE>. |
4882 | |
5119 | |
4883 | =head3 COROUTINES |
5120 | =head3 COROUTINES |
4884 | |
5121 | |
4885 | Libev is very accommodating to coroutines ("cooperative threads"): |
5122 | Libev is very accommodating to coroutines ("cooperative threads"): |
4886 | libev fully supports nesting calls to its functions from different |
5123 | libev fully supports nesting calls to its functions from different |
… | |
… | |
5155 | structure (guaranteed by POSIX but not by ISO C for example), but it also |
5392 | structure (guaranteed by POSIX but not by ISO C for example), but it also |
5156 | assumes that the same (machine) code can be used to call any watcher |
5393 | assumes that the same (machine) code can be used to call any watcher |
5157 | callback: The watcher callbacks have different type signatures, but libev |
5394 | callback: The watcher callbacks have different type signatures, but libev |
5158 | calls them using an C<ev_watcher *> internally. |
5395 | calls them using an C<ev_watcher *> internally. |
5159 | |
5396 | |
|
|
5397 | =item null pointers and integer zero are represented by 0 bytes |
|
|
5398 | |
|
|
5399 | Libev uses C<memset> to initialise structs and arrays to C<0> bytes, and |
|
|
5400 | relies on this setting pointers and integers to null. |
|
|
5401 | |
5160 | =item pointer accesses must be thread-atomic |
5402 | =item pointer accesses must be thread-atomic |
5161 | |
5403 | |
5162 | Accessing a pointer value must be atomic, it must both be readable and |
5404 | Accessing a pointer value must be atomic, it must both be readable and |
5163 | writable in one piece - this is the case on all current architectures. |
5405 | writable in one piece - this is the case on all current architectures. |
5164 | |
5406 | |
… | |
… | |
5177 | thread" or will block signals process-wide, both behaviours would |
5419 | thread" or will block signals process-wide, both behaviours would |
5178 | be compatible with libev. Interaction between C<sigprocmask> and |
5420 | be compatible with libev. Interaction between C<sigprocmask> and |
5179 | C<pthread_sigmask> could complicate things, however. |
5421 | C<pthread_sigmask> could complicate things, however. |
5180 | |
5422 | |
5181 | The most portable way to handle signals is to block signals in all threads |
5423 | The most portable way to handle signals is to block signals in all threads |
5182 | except the initial one, and run the default loop in the initial thread as |
5424 | except the initial one, and run the signal handling loop in the initial |
5183 | well. |
5425 | thread as well. |
5184 | |
5426 | |
5185 | =item C<long> must be large enough for common memory allocation sizes |
5427 | =item C<long> must be large enough for common memory allocation sizes |
5186 | |
5428 | |
5187 | To improve portability and simplify its API, libev uses C<long> internally |
5429 | To improve portability and simplify its API, libev uses C<long> internally |
5188 | instead of C<size_t> when allocating its data structures. On non-POSIX |
5430 | instead of C<size_t> when allocating its data structures. On non-POSIX |
… | |
… | |
5292 | =over 4 |
5534 | =over 4 |
5293 | |
5535 | |
5294 | =item C<EV_COMPAT3> backwards compatibility mechanism |
5536 | =item C<EV_COMPAT3> backwards compatibility mechanism |
5295 | |
5537 | |
5296 | The backward compatibility mechanism can be controlled by |
5538 | The backward compatibility mechanism can be controlled by |
5297 | C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING> |
5539 | C<EV_COMPAT3>. See L</"PREPROCESSOR SYMBOLS/MACROS"> in the L</EMBEDDING> |
5298 | section. |
5540 | section. |
5299 | |
5541 | |
5300 | =item C<ev_default_destroy> and C<ev_default_fork> have been removed |
5542 | =item C<ev_default_destroy> and C<ev_default_fork> have been removed |
5301 | |
5543 | |
5302 | These calls can be replaced easily by their C<ev_loop_xxx> counterparts: |
5544 | These calls can be replaced easily by their C<ev_loop_xxx> counterparts: |
… | |
… | |
5345 | =over 4 |
5587 | =over 4 |
5346 | |
5588 | |
5347 | =item active |
5589 | =item active |
5348 | |
5590 | |
5349 | A watcher is active as long as it has been started and not yet stopped. |
5591 | A watcher is active as long as it has been started and not yet stopped. |
5350 | See L<WATCHER STATES> for details. |
5592 | See L</WATCHER STATES> for details. |
5351 | |
5593 | |
5352 | =item application |
5594 | =item application |
5353 | |
5595 | |
5354 | In this document, an application is whatever is using libev. |
5596 | In this document, an application is whatever is using libev. |
5355 | |
5597 | |
… | |
… | |
5391 | watchers and events. |
5633 | watchers and events. |
5392 | |
5634 | |
5393 | =item pending |
5635 | =item pending |
5394 | |
5636 | |
5395 | A watcher is pending as soon as the corresponding event has been |
5637 | A watcher is pending as soon as the corresponding event has been |
5396 | detected. See L<WATCHER STATES> for details. |
5638 | detected. See L</WATCHER STATES> for details. |
5397 | |
5639 | |
5398 | =item real time |
5640 | =item real time |
5399 | |
5641 | |
5400 | The physical time that is observed. It is apparently strictly monotonic :) |
5642 | The physical time that is observed. It is apparently strictly monotonic :) |
5401 | |
5643 | |