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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 | (probably because of a bug), so this is not (yet?) a generic event polling |
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604 | interface. |
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605 | |
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606 | To work around this latter problem, the current version of libev uses |
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607 | epoll as a fallback for file deescriptor types that do not work. Epoll |
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608 | is used in, kind of, slow mode that hopefully avoids most of its design |
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609 | problems. |
548 | |
610 | |
549 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
611 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
550 | C<EVBACKEND_POLL>. |
612 | C<EVBACKEND_POLL>. |
551 | |
613 | |
552 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
614 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
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569 | kernel is more efficient (which says nothing about its actual speed, of |
631 | 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 |
632 | 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 |
633 | cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to |
572 | two event changes per incident. Support for C<fork ()> is very bad (you |
634 | two event changes per incident. Support for C<fork ()> is very bad (you |
573 | might have to leak fd's on fork, but it's more sane than epoll) and it |
635 | might have to leak fd's on fork, but it's more sane than epoll) and it |
574 | drops fds silently in similarly hard-to-detect cases |
636 | drops fds silently in similarly hard-to-detect cases. |
575 | |
637 | |
576 | This backend usually performs well under most conditions. |
638 | This backend usually performs well under most conditions. |
577 | |
639 | |
578 | While nominally embeddable in other event loops, this doesn't work |
640 | 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 |
641 | 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 |
715 | Example: Use whatever libev has to offer, but make sure that kqueue is |
654 | used if available. |
716 | used if available. |
655 | |
717 | |
656 | struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE); |
718 | struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE); |
657 | |
719 | |
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720 | Example: Similarly, on linux, you mgiht want to take advantage of the |
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721 | linux aio backend if possible, but fall back to something else if that |
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722 | isn't available. |
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723 | |
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724 | struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_LINUXAIO); |
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725 | |
658 | =item ev_loop_destroy (loop) |
726 | =item ev_loop_destroy (loop) |
659 | |
727 | |
660 | Destroys an event loop object (frees all memory and kernel state |
728 | 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 |
729 | 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 |
730 | 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> |
746 | If you need dynamically allocated loops it is better to use C<ev_loop_new> |
679 | and C<ev_loop_destroy>. |
747 | and C<ev_loop_destroy>. |
680 | |
748 | |
681 | =item ev_loop_fork (loop) |
749 | =item ev_loop_fork (loop) |
682 | |
750 | |
683 | This function sets a flag that causes subsequent C<ev_run> iterations to |
751 | This function sets a flag that causes subsequent C<ev_run> iterations |
684 | reinitialise the kernel state for backends that have one. Despite the |
752 | 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 |
753 | 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 |
754 | watchers (except inside an C<ev_prepare> callback), but it makes most |
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755 | sense after forking, in the child process. You I<must> call it (or use |
687 | child before resuming or calling C<ev_run>. |
756 | C<EVFLAG_FORKCHECK>) in the child before resuming or calling C<ev_run>. |
688 | |
757 | |
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758 | In addition, if you want to reuse a loop (via this function or |
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759 | C<EVFLAG_FORKCHECK>), you I<also> have to ignore C<SIGPIPE>. |
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760 | |
689 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
761 | 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 |
762 | 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 |
763 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
692 | during fork. |
764 | during fork. |
693 | |
765 | |
694 | On the other hand, you only need to call this function in the child |
766 | On the other hand, you only need to call this function in the child |
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764 | |
836 | |
765 | This function is rarely useful, but when some event callback runs for a |
837 | 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 |
838 | very long time without entering the event loop, updating libev's idea of |
767 | the current time is a good idea. |
839 | the current time is a good idea. |
768 | |
840 | |
769 | See also L<The special problem of time updates> in the C<ev_timer> section. |
841 | See also L</The special problem of time updates> in the C<ev_timer> section. |
770 | |
842 | |
771 | =item ev_suspend (loop) |
843 | =item ev_suspend (loop) |
772 | |
844 | |
773 | =item ev_resume (loop) |
845 | =item ev_resume (loop) |
774 | |
846 | |
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792 | without a previous call to C<ev_suspend>. |
864 | without a previous call to C<ev_suspend>. |
793 | |
865 | |
794 | Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the |
866 | Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the |
795 | event loop time (see C<ev_now_update>). |
867 | event loop time (see C<ev_now_update>). |
796 | |
868 | |
797 | =item ev_run (loop, int flags) |
869 | =item bool ev_run (loop, int flags) |
798 | |
870 | |
799 | Finally, this is it, the event handler. This function usually is called |
871 | 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 |
872 | 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 |
873 | 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 |
874 | the watcher callbacks, and then repeat the whole process indefinitely: This |
803 | is why event loops are called I<loops>. |
875 | is why event loops are called I<loops>. |
804 | |
876 | |
805 | If the flags argument is specified as C<0>, it will keep handling events |
877 | 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 |
878 | until either no event watchers are active anymore or C<ev_break> was |
807 | called. |
879 | called. |
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880 | |
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881 | The return value is false if there are no more active watchers (which |
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882 | usually means "all jobs done" or "deadlock"), and true in all other cases |
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883 | (which usually means " you should call C<ev_run> again"). |
808 | |
884 | |
809 | Please note that an explicit C<ev_break> is usually better than |
885 | 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 |
886 | relying on all watchers to be stopped when deciding when a program has |
811 | finished (especially in interactive programs), but having a program |
887 | finished (especially in interactive programs), but having a program |
812 | that automatically loops as long as it has to and no longer by virtue |
888 | 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 |
889 | of relying on its watchers stopping correctly, that is truly a thing of |
814 | beauty. |
890 | beauty. |
815 | |
891 | |
816 | This function is also I<mostly> exception-safe - you can break out of |
892 | 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++ |
893 | 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 |
894 | exception and so on. This does not decrement the C<ev_depth> value, nor |
819 | will it clear any outstanding C<EVBREAK_ONE> breaks. |
895 | will it clear any outstanding C<EVBREAK_ONE> breaks. |
820 | |
896 | |
821 | A flags value of C<EVRUN_NOWAIT> will look for new events, will handle |
897 | 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 |
898 | 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.). |
1088 | invoke the actual watchers inside another context (another thread etc.). |
1013 | |
1089 | |
1014 | If you want to reset the callback, use C<ev_invoke_pending> as new |
1090 | If you want to reset the callback, use C<ev_invoke_pending> as new |
1015 | callback. |
1091 | callback. |
1016 | |
1092 | |
1017 | =item ev_set_loop_release_cb (loop, void (*release)(EV_P), void (*acquire)(EV_P)) |
1093 | =item ev_set_loop_release_cb (loop, void (*release)(EV_P) throw (), void (*acquire)(EV_P) throw ()) |
1018 | |
1094 | |
1019 | Sometimes you want to share the same loop between multiple threads. This |
1095 | 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 |
1096 | can be done relatively simply by putting mutex_lock/unlock calls around |
1021 | each call to a libev function. |
1097 | each call to a libev function. |
1022 | |
1098 | |
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1170 | |
1246 | |
1171 | =item C<EV_PREPARE> |
1247 | =item C<EV_PREPARE> |
1172 | |
1248 | |
1173 | =item C<EV_CHECK> |
1249 | =item C<EV_CHECK> |
1174 | |
1250 | |
1175 | All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts |
1251 | 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 |
1252 | 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 |
1253 | just after C<ev_run> has gathered them, but before it queues any callbacks |
|
|
1254 | for any received events. That means C<ev_prepare> watchers are the last |
|
|
1255 | watchers invoked before the event loop sleeps or polls for new events, and |
|
|
1256 | C<ev_check> watchers will be invoked before any other watchers of the same |
|
|
1257 | or lower priority within an event loop iteration. |
|
|
1258 | |
1178 | received events. Callbacks of both watcher types can start and stop as |
1259 | 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 |
1260 | 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 |
1261 | C<ev_prepare> watcher might start an idle watcher to keep C<ev_run> from |
1181 | C<ev_run> from blocking). |
1262 | blocking). |
1182 | |
1263 | |
1183 | =item C<EV_EMBED> |
1264 | =item C<EV_EMBED> |
1184 | |
1265 | |
1185 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1266 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1186 | |
1267 | |
… | |
… | |
1309 | |
1390 | |
1310 | =item callback ev_cb (ev_TYPE *watcher) |
1391 | =item callback ev_cb (ev_TYPE *watcher) |
1311 | |
1392 | |
1312 | Returns the callback currently set on the watcher. |
1393 | Returns the callback currently set on the watcher. |
1313 | |
1394 | |
1314 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1395 | =item ev_set_cb (ev_TYPE *watcher, callback) |
1315 | |
1396 | |
1316 | Change the callback. You can change the callback at virtually any time |
1397 | Change the callback. You can change the callback at virtually any time |
1317 | (modulo threads). |
1398 | (modulo threads). |
1318 | |
1399 | |
1319 | =item ev_set_priority (ev_TYPE *watcher, int priority) |
1400 | =item ev_set_priority (ev_TYPE *watcher, int priority) |
… | |
… | |
1337 | or might not have been clamped to the valid range. |
1418 | or might not have been clamped to the valid range. |
1338 | |
1419 | |
1339 | The default priority used by watchers when no priority has been set is |
1420 | 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 :). |
1421 | always C<0>, which is supposed to not be too high and not be too low :). |
1341 | |
1422 | |
1342 | See L<WATCHER PRIORITY MODELS>, below, for a more thorough treatment of |
1423 | See L</WATCHER PRIORITY MODELS>, below, for a more thorough treatment of |
1343 | priorities. |
1424 | priorities. |
1344 | |
1425 | |
1345 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
1426 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
1346 | |
1427 | |
1347 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
1428 | 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 |
1453 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
1373 | functions that do not need a watcher. |
1454 | functions that do not need a watcher. |
1374 | |
1455 | |
1375 | =back |
1456 | =back |
1376 | |
1457 | |
1377 | See also the L<ASSOCIATING CUSTOM DATA WITH A WATCHER> and L<BUILDING YOUR |
1458 | See also the L</ASSOCIATING CUSTOM DATA WITH A WATCHER> and L</BUILDING YOUR |
1378 | OWN COMPOSITE WATCHERS> idioms. |
1459 | OWN COMPOSITE WATCHERS> idioms. |
1379 | |
1460 | |
1380 | =head2 WATCHER STATES |
1461 | =head2 WATCHER STATES |
1381 | |
1462 | |
1382 | There are various watcher states mentioned throughout this manual - |
1463 | There are various watcher states mentioned throughout this manual - |
… | |
… | |
1384 | transition between them will be described in more detail - and while these |
1465 | transition between them will be described in more detail - and while these |
1385 | rules might look complicated, they usually do "the right thing". |
1466 | rules might look complicated, they usually do "the right thing". |
1386 | |
1467 | |
1387 | =over 4 |
1468 | =over 4 |
1388 | |
1469 | |
1389 | =item initialiased |
1470 | =item initialised |
1390 | |
1471 | |
1391 | Before a watcher can be registered with the event loop it has to be |
1472 | 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 |
1473 | 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. |
1474 | C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
1394 | |
1475 | |
… | |
… | |
1592 | |
1673 | |
1593 | But really, best use non-blocking mode. |
1674 | But really, best use non-blocking mode. |
1594 | |
1675 | |
1595 | =head3 The special problem of disappearing file descriptors |
1676 | =head3 The special problem of disappearing file descriptors |
1596 | |
1677 | |
1597 | Some backends (e.g. kqueue, epoll) need to be told about closing a file |
1678 | 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, |
1679 | 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 |
1680 | 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 |
1681 | 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 |
1682 | 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 |
1683 | is registered with libev, there is no efficient way to see that this is, |
1603 | fact, a different file descriptor. |
1684 | in fact, a different file descriptor. |
1604 | |
1685 | |
1605 | To avoid having to explicitly tell libev about such cases, libev follows |
1686 | 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 |
1687 | 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 |
1688 | 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 |
1689 | 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 |
1738 | when you rarely read from a file instead of from a socket, and want to |
1658 | reuse the same code path. |
1739 | reuse the same code path. |
1659 | |
1740 | |
1660 | =head3 The special problem of fork |
1741 | =head3 The special problem of fork |
1661 | |
1742 | |
1662 | Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit |
1743 | Some backends (epoll, kqueue, probably linuxaio) do not support C<fork ()> |
1663 | useless behaviour. Libev fully supports fork, but needs to be told about |
1744 | 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. |
1745 | to be told about it in the child if you want to continue to use it in the |
|
|
1746 | child. |
1665 | |
1747 | |
1666 | To support fork in your child processes, you have to call C<ev_loop_fork |
1748 | 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 |
1749 | ()> after a fork in the child, enable C<EVFLAG_FORKCHECK>, or resort to |
1668 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
1750 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
1669 | |
1751 | |
… | |
… | |
1870 | callback (EV_P_ ev_timer *w, int revents) |
1952 | callback (EV_P_ ev_timer *w, int revents) |
1871 | { |
1953 | { |
1872 | // calculate when the timeout would happen |
1954 | // calculate when the timeout would happen |
1873 | ev_tstamp after = last_activity - ev_now (EV_A) + timeout; |
1955 | ev_tstamp after = last_activity - ev_now (EV_A) + timeout; |
1874 | |
1956 | |
1875 | // if negative, it means we the timeout already occured |
1957 | // if negative, it means we the timeout already occurred |
1876 | if (after < 0.) |
1958 | if (after < 0.) |
1877 | { |
1959 | { |
1878 | // timeout occurred, take action |
1960 | // timeout occurred, take action |
1879 | } |
1961 | } |
1880 | else |
1962 | else |
… | |
… | |
1898 | |
1980 | |
1899 | Otherwise, we now the earliest time at which the timeout would trigger, |
1981 | Otherwise, we now the earliest time at which the timeout would trigger, |
1900 | and simply start the timer with this timeout value. |
1982 | and simply start the timer with this timeout value. |
1901 | |
1983 | |
1902 | In other words, each time the callback is invoked it will check whether |
1984 | 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 |
1985 | the timeout occurred. If not, it will simply reschedule itself to check |
1904 | again at the earliest time it could time out. Rinse. Repeat. |
1986 | again at the earliest time it could time out. Rinse. Repeat. |
1905 | |
1987 | |
1906 | This scheme causes more callback invocations (about one every 60 seconds |
1988 | This scheme causes more callback invocations (about one every 60 seconds |
1907 | minus half the average time between activity), but virtually no calls to |
1989 | minus half the average time between activity), but virtually no calls to |
1908 | libev to change the timeout. |
1990 | libev to change the timeout. |
… | |
… | |
1922 | if (activity detected) |
2004 | if (activity detected) |
1923 | last_activity = ev_now (EV_A); |
2005 | last_activity = ev_now (EV_A); |
1924 | |
2006 | |
1925 | When your timeout value changes, then the timeout can be changed by simply |
2007 | 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 |
2008 | providing a new value, stopping the timer and calling the callback, which |
1927 | will agaion do the right thing (for example, time out immediately :). |
2009 | will again do the right thing (for example, time out immediately :). |
1928 | |
2010 | |
1929 | timeout = new_value; |
2011 | timeout = new_value; |
1930 | ev_timer_stop (EV_A_ &timer); |
2012 | ev_timer_stop (EV_A_ &timer); |
1931 | callback (EV_A_ &timer, 0); |
2013 | callback (EV_A_ &timer, 0); |
1932 | |
2014 | |
… | |
… | |
2015 | |
2097 | |
2016 | The relative timeouts are calculated relative to the C<ev_now ()> |
2098 | 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 |
2099 | 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 |
2100 | 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 |
2101 | 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: |
2102 | timeout on the current time, use something like the following to adjust |
|
|
2103 | for it: |
2021 | |
2104 | |
2022 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
2105 | ev_timer_set (&timer, after + (ev_time () - ev_now ()), 0.); |
2023 | |
2106 | |
2024 | If the event loop is suspended for a long time, you can also force an |
2107 | 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 |
2108 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
2026 | ()>. |
2109 | ()>, although that will push the event time of all outstanding events |
|
|
2110 | further into the future. |
2027 | |
2111 | |
2028 | =head3 The special problem of unsynchronised clocks |
2112 | =head3 The special problem of unsynchronised clocks |
2029 | |
2113 | |
2030 | Modern systems have a variety of clocks - libev itself uses the normal |
2114 | 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 |
2115 | "wall clock" clock and, if available, the monotonic clock (to avoid time |
… | |
… | |
2094 | |
2178 | |
2095 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
2179 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
2096 | |
2180 | |
2097 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
2181 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
2098 | |
2182 | |
2099 | Configure the timer to trigger after C<after> seconds. If C<repeat> |
2183 | 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 |
2184 | 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 |
2185 | automatically be stopped once the timeout is reached. If it is positive, |
2102 | configured to trigger again C<repeat> seconds later, again, and again, |
2186 | then the timer will automatically be configured to trigger again C<repeat> |
2103 | until stopped manually. |
2187 | seconds later, again, and again, until stopped manually. |
2104 | |
2188 | |
2105 | The timer itself will do a best-effort at avoiding drift, that is, if |
2189 | 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 |
2190 | 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 |
2191 | 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 |
2192 | keep up with the timer (because it takes longer than those 10 seconds to |
… | |
… | |
2127 | =item If the timer is repeating, make the C<repeat> value the new timeout |
2211 | =item If the timer is repeating, make the C<repeat> value the new timeout |
2128 | and start the timer, if necessary. |
2212 | and start the timer, if necessary. |
2129 | |
2213 | |
2130 | =back |
2214 | =back |
2131 | |
2215 | |
2132 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
2216 | This sounds a bit complicated, see L</Be smart about timeouts>, above, for a |
2133 | usage example. |
2217 | usage example. |
2134 | |
2218 | |
2135 | =item ev_tstamp ev_timer_remaining (loop, ev_timer *) |
2219 | =item ev_tstamp ev_timer_remaining (loop, ev_timer *) |
2136 | |
2220 | |
2137 | Returns the remaining time until a timer fires. If the timer is active, |
2221 | Returns the remaining time until a timer fires. If the timer is active, |
… | |
… | |
2190 | Periodic watchers are also timers of a kind, but they are very versatile |
2274 | Periodic watchers are also timers of a kind, but they are very versatile |
2191 | (and unfortunately a bit complex). |
2275 | (and unfortunately a bit complex). |
2192 | |
2276 | |
2193 | Unlike C<ev_timer>, periodic watchers are not based on real time (or |
2277 | Unlike C<ev_timer>, periodic watchers are not based on real time (or |
2194 | relative time, the physical time that passes) but on wall clock time |
2278 | relative time, the physical time that passes) but on wall clock time |
2195 | (absolute time, the thing you can read on your calender or clock). The |
2279 | (absolute time, the thing you can read on your calendar or clock). The |
2196 | difference is that wall clock time can run faster or slower than real |
2280 | difference is that wall clock time can run faster or slower than real |
2197 | time, and time jumps are not uncommon (e.g. when you adjust your |
2281 | time, and time jumps are not uncommon (e.g. when you adjust your |
2198 | wrist-watch). |
2282 | wrist-watch). |
2199 | |
2283 | |
2200 | You can tell a periodic watcher to trigger after some specific point |
2284 | You can tell a periodic watcher to trigger after some specific point |
… | |
… | |
2205 | C<ev_timer>, which would still trigger roughly 10 seconds after starting |
2289 | C<ev_timer>, which would still trigger roughly 10 seconds after starting |
2206 | it, as it uses a relative timeout). |
2290 | it, as it uses a relative timeout). |
2207 | |
2291 | |
2208 | C<ev_periodic> watchers can also be used to implement vastly more complex |
2292 | C<ev_periodic> watchers can also be used to implement vastly more complex |
2209 | timers, such as triggering an event on each "midnight, local time", or |
2293 | timers, such as triggering an event on each "midnight, local time", or |
2210 | other complicated rules. This cannot be done with C<ev_timer> watchers, as |
2294 | other complicated rules. This cannot easily be done with C<ev_timer> |
2211 | those cannot react to time jumps. |
2295 | watchers, as those cannot react to time jumps. |
2212 | |
2296 | |
2213 | As with timers, the callback is guaranteed to be invoked only when the |
2297 | As with timers, the callback is guaranteed to be invoked only when the |
2214 | point in time where it is supposed to trigger has passed. If multiple |
2298 | point in time where it is supposed to trigger has passed. If multiple |
2215 | timers become ready during the same loop iteration then the ones with |
2299 | timers become ready during the same loop iteration then the ones with |
2216 | earlier time-out values are invoked before ones with later time-out values |
2300 | earlier time-out values are invoked before ones with later time-out values |
… | |
… | |
2302 | |
2386 | |
2303 | NOTE: I<< This callback must always return a time that is higher than or |
2387 | NOTE: I<< This callback must always return a time that is higher than or |
2304 | equal to the passed C<now> value >>. |
2388 | equal to the passed C<now> value >>. |
2305 | |
2389 | |
2306 | This can be used to create very complex timers, such as a timer that |
2390 | This can be used to create very complex timers, such as a timer that |
2307 | triggers on "next midnight, local time". To do this, you would calculate the |
2391 | triggers on "next midnight, local time". To do this, you would calculate |
2308 | next midnight after C<now> and return the timestamp value for this. How |
2392 | the next midnight after C<now> and return the timestamp value for |
2309 | you do this is, again, up to you (but it is not trivial, which is the main |
2393 | this. Here is a (completely untested, no error checking) example on how to |
2310 | reason I omitted it as an example). |
2394 | do this: |
|
|
2395 | |
|
|
2396 | #include <time.h> |
|
|
2397 | |
|
|
2398 | static ev_tstamp |
|
|
2399 | my_rescheduler (ev_periodic *w, ev_tstamp now) |
|
|
2400 | { |
|
|
2401 | time_t tnow = (time_t)now; |
|
|
2402 | struct tm tm; |
|
|
2403 | localtime_r (&tnow, &tm); |
|
|
2404 | |
|
|
2405 | tm.tm_sec = tm.tm_min = tm.tm_hour = 0; // midnight current day |
|
|
2406 | ++tm.tm_mday; // midnight next day |
|
|
2407 | |
|
|
2408 | return mktime (&tm); |
|
|
2409 | } |
|
|
2410 | |
|
|
2411 | Note: this code might run into trouble on days that have more then two |
|
|
2412 | midnights (beginning and end). |
2311 | |
2413 | |
2312 | =back |
2414 | =back |
2313 | |
2415 | |
2314 | =item ev_periodic_again (loop, ev_periodic *) |
2416 | =item ev_periodic_again (loop, ev_periodic *) |
2315 | |
2417 | |
… | |
… | |
2380 | |
2482 | |
2381 | ev_periodic hourly_tick; |
2483 | ev_periodic hourly_tick; |
2382 | ev_periodic_init (&hourly_tick, clock_cb, |
2484 | ev_periodic_init (&hourly_tick, clock_cb, |
2383 | fmod (ev_now (loop), 3600.), 3600., 0); |
2485 | fmod (ev_now (loop), 3600.), 3600., 0); |
2384 | ev_periodic_start (loop, &hourly_tick); |
2486 | ev_periodic_start (loop, &hourly_tick); |
2385 | |
2487 | |
2386 | |
2488 | |
2387 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
2489 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
2388 | |
2490 | |
2389 | Signal watchers will trigger an event when the process receives a specific |
2491 | Signal watchers will trigger an event when the process receives a specific |
2390 | signal one or more times. Even though signals are very asynchronous, libev |
2492 | signal one or more times. Even though signals are very asynchronous, libev |
… | |
… | |
2400 | only within the same loop, i.e. you can watch for C<SIGINT> in your |
2502 | only within the same loop, i.e. you can watch for C<SIGINT> in your |
2401 | default loop and for C<SIGIO> in another loop, but you cannot watch for |
2503 | default loop and for C<SIGIO> in another loop, but you cannot watch for |
2402 | C<SIGINT> in both the default loop and another loop at the same time. At |
2504 | C<SIGINT> in both the default loop and another loop at the same time. At |
2403 | the moment, C<SIGCHLD> is permanently tied to the default loop. |
2505 | the moment, C<SIGCHLD> is permanently tied to the default loop. |
2404 | |
2506 | |
2405 | When the first watcher gets started will libev actually register something |
2507 | Only after the first watcher for a signal is started will libev actually |
2406 | with the kernel (thus it coexists with your own signal handlers as long as |
2508 | register something with the kernel. It thus coexists with your own signal |
2407 | you don't register any with libev for the same signal). |
2509 | handlers as long as you don't register any with libev for the same signal. |
2408 | |
2510 | |
2409 | If possible and supported, libev will install its handlers with |
2511 | If possible and supported, libev will install its handlers with |
2410 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2512 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2411 | not be unduly interrupted. If you have a problem with system calls getting |
2513 | not be unduly interrupted. If you have a problem with system calls getting |
2412 | interrupted by signals you can block all signals in an C<ev_check> watcher |
2514 | interrupted by signals you can block all signals in an C<ev_check> watcher |
… | |
… | |
2597 | |
2699 | |
2598 | =head2 C<ev_stat> - did the file attributes just change? |
2700 | =head2 C<ev_stat> - did the file attributes just change? |
2599 | |
2701 | |
2600 | This watches a file system path for attribute changes. That is, it calls |
2702 | This watches a file system path for attribute changes. That is, it calls |
2601 | C<stat> on that path in regular intervals (or when the OS says it changed) |
2703 | C<stat> on that path in regular intervals (or when the OS says it changed) |
2602 | and sees if it changed compared to the last time, invoking the callback if |
2704 | and sees if it changed compared to the last time, invoking the callback |
2603 | it did. |
2705 | if it did. Starting the watcher C<stat>'s the file, so only changes that |
|
|
2706 | happen after the watcher has been started will be reported. |
2604 | |
2707 | |
2605 | The path does not need to exist: changing from "path exists" to "path does |
2708 | The path does not need to exist: changing from "path exists" to "path does |
2606 | not exist" is a status change like any other. The condition "path does not |
2709 | not exist" is a status change like any other. The condition "path does not |
2607 | exist" (or more correctly "path cannot be stat'ed") is signified by the |
2710 | exist" (or more correctly "path cannot be stat'ed") is signified by the |
2608 | C<st_nlink> field being zero (which is otherwise always forced to be at |
2711 | C<st_nlink> field being zero (which is otherwise always forced to be at |
… | |
… | |
2838 | Apart from keeping your process non-blocking (which is a useful |
2941 | Apart from keeping your process non-blocking (which is a useful |
2839 | effect on its own sometimes), idle watchers are a good place to do |
2942 | effect on its own sometimes), idle watchers are a good place to do |
2840 | "pseudo-background processing", or delay processing stuff to after the |
2943 | "pseudo-background processing", or delay processing stuff to after the |
2841 | event loop has handled all outstanding events. |
2944 | event loop has handled all outstanding events. |
2842 | |
2945 | |
|
|
2946 | =head3 Abusing an C<ev_idle> watcher for its side-effect |
|
|
2947 | |
|
|
2948 | As long as there is at least one active idle watcher, libev will never |
|
|
2949 | sleep unnecessarily. Or in other words, it will loop as fast as possible. |
|
|
2950 | For this to work, the idle watcher doesn't need to be invoked at all - the |
|
|
2951 | lowest priority will do. |
|
|
2952 | |
|
|
2953 | This mode of operation can be useful together with an C<ev_check> watcher, |
|
|
2954 | to do something on each event loop iteration - for example to balance load |
|
|
2955 | between different connections. |
|
|
2956 | |
|
|
2957 | See L</Abusing an ev_check watcher for its side-effect> for a longer |
|
|
2958 | example. |
|
|
2959 | |
2843 | =head3 Watcher-Specific Functions and Data Members |
2960 | =head3 Watcher-Specific Functions and Data Members |
2844 | |
2961 | |
2845 | =over 4 |
2962 | =over 4 |
2846 | |
2963 | |
2847 | =item ev_idle_init (ev_idle *, callback) |
2964 | =item ev_idle_init (ev_idle *, callback) |
… | |
… | |
2858 | callback, free it. Also, use no error checking, as usual. |
2975 | callback, free it. Also, use no error checking, as usual. |
2859 | |
2976 | |
2860 | static void |
2977 | static void |
2861 | idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
2978 | idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
2862 | { |
2979 | { |
|
|
2980 | // stop the watcher |
|
|
2981 | ev_idle_stop (loop, w); |
|
|
2982 | |
|
|
2983 | // now we can free it |
2863 | free (w); |
2984 | free (w); |
|
|
2985 | |
2864 | // now do something you wanted to do when the program has |
2986 | // now do something you wanted to do when the program has |
2865 | // no longer anything immediate to do. |
2987 | // no longer anything immediate to do. |
2866 | } |
2988 | } |
2867 | |
2989 | |
2868 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
2990 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
… | |
… | |
2870 | ev_idle_start (loop, idle_watcher); |
2992 | ev_idle_start (loop, idle_watcher); |
2871 | |
2993 | |
2872 | |
2994 | |
2873 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
2995 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
2874 | |
2996 | |
2875 | Prepare and check watchers are usually (but not always) used in pairs: |
2997 | Prepare and check watchers are often (but not always) used in pairs: |
2876 | prepare watchers get invoked before the process blocks and check watchers |
2998 | prepare watchers get invoked before the process blocks and check watchers |
2877 | afterwards. |
2999 | afterwards. |
2878 | |
3000 | |
2879 | You I<must not> call C<ev_run> or similar functions that enter |
3001 | You I<must not> call C<ev_run> (or similar functions that enter the |
2880 | the current event loop from either C<ev_prepare> or C<ev_check> |
3002 | current event loop) or C<ev_loop_fork> from either C<ev_prepare> or |
2881 | watchers. Other loops than the current one are fine, however. The |
3003 | C<ev_check> watchers. Other loops than the current one are fine, |
2882 | rationale behind this is that you do not need to check for recursion in |
3004 | however. The rationale behind this is that you do not need to check |
2883 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
3005 | for recursion in those watchers, i.e. the sequence will always be |
2884 | C<ev_check> so if you have one watcher of each kind they will always be |
3006 | C<ev_prepare>, blocking, C<ev_check> so if you have one watcher of each |
2885 | called in pairs bracketing the blocking call. |
3007 | kind they will always be called in pairs bracketing the blocking call. |
2886 | |
3008 | |
2887 | Their main purpose is to integrate other event mechanisms into libev and |
3009 | Their main purpose is to integrate other event mechanisms into libev and |
2888 | their use is somewhat advanced. They could be used, for example, to track |
3010 | their use is somewhat advanced. They could be used, for example, to track |
2889 | variable changes, implement your own watchers, integrate net-snmp or a |
3011 | variable changes, implement your own watchers, integrate net-snmp or a |
2890 | coroutine library and lots more. They are also occasionally useful if |
3012 | coroutine library and lots more. They are also occasionally useful if |
… | |
… | |
2908 | with priority higher than or equal to the event loop and one coroutine |
3030 | with priority higher than or equal to the event loop and one coroutine |
2909 | of lower priority, but only once, using idle watchers to keep the event |
3031 | of lower priority, but only once, using idle watchers to keep the event |
2910 | loop from blocking if lower-priority coroutines are active, thus mapping |
3032 | loop from blocking if lower-priority coroutines are active, thus mapping |
2911 | low-priority coroutines to idle/background tasks). |
3033 | low-priority coroutines to idle/background tasks). |
2912 | |
3034 | |
2913 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
3035 | When used for this purpose, it is recommended to give C<ev_check> watchers |
2914 | priority, to ensure that they are being run before any other watchers |
3036 | highest (C<EV_MAXPRI>) priority, to ensure that they are being run before |
2915 | after the poll (this doesn't matter for C<ev_prepare> watchers). |
3037 | any other watchers after the poll (this doesn't matter for C<ev_prepare> |
|
|
3038 | watchers). |
2916 | |
3039 | |
2917 | Also, C<ev_check> watchers (and C<ev_prepare> watchers, too) should not |
3040 | Also, C<ev_check> watchers (and C<ev_prepare> watchers, too) should not |
2918 | activate ("feed") events into libev. While libev fully supports this, they |
3041 | activate ("feed") events into libev. While libev fully supports this, they |
2919 | might get executed before other C<ev_check> watchers did their job. As |
3042 | might get executed before other C<ev_check> watchers did their job. As |
2920 | C<ev_check> watchers are often used to embed other (non-libev) event |
3043 | C<ev_check> watchers are often used to embed other (non-libev) event |
2921 | loops those other event loops might be in an unusable state until their |
3044 | loops those other event loops might be in an unusable state until their |
2922 | C<ev_check> watcher ran (always remind yourself to coexist peacefully with |
3045 | C<ev_check> watcher ran (always remind yourself to coexist peacefully with |
2923 | others). |
3046 | others). |
|
|
3047 | |
|
|
3048 | =head3 Abusing an C<ev_check> watcher for its side-effect |
|
|
3049 | |
|
|
3050 | C<ev_check> (and less often also C<ev_prepare>) watchers can also be |
|
|
3051 | useful because they are called once per event loop iteration. For |
|
|
3052 | example, if you want to handle a large number of connections fairly, you |
|
|
3053 | normally only do a bit of work for each active connection, and if there |
|
|
3054 | is more work to do, you wait for the next event loop iteration, so other |
|
|
3055 | connections have a chance of making progress. |
|
|
3056 | |
|
|
3057 | Using an C<ev_check> watcher is almost enough: it will be called on the |
|
|
3058 | next event loop iteration. However, that isn't as soon as possible - |
|
|
3059 | without external events, your C<ev_check> watcher will not be invoked. |
|
|
3060 | |
|
|
3061 | This is where C<ev_idle> watchers come in handy - all you need is a |
|
|
3062 | single global idle watcher that is active as long as you have one active |
|
|
3063 | C<ev_check> watcher. The C<ev_idle> watcher makes sure the event loop |
|
|
3064 | will not sleep, and the C<ev_check> watcher makes sure a callback gets |
|
|
3065 | invoked. Neither watcher alone can do that. |
2924 | |
3066 | |
2925 | =head3 Watcher-Specific Functions and Data Members |
3067 | =head3 Watcher-Specific Functions and Data Members |
2926 | |
3068 | |
2927 | =over 4 |
3069 | =over 4 |
2928 | |
3070 | |
… | |
… | |
3129 | |
3271 | |
3130 | =over 4 |
3272 | =over 4 |
3131 | |
3273 | |
3132 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
3274 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
3133 | |
3275 | |
3134 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
3276 | =item ev_embed_set (ev_embed *, struct ev_loop *embedded_loop) |
3135 | |
3277 | |
3136 | Configures the watcher to embed the given loop, which must be |
3278 | Configures the watcher to embed the given loop, which must be |
3137 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
3279 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
3138 | invoked automatically, otherwise it is the responsibility of the callback |
3280 | invoked automatically, otherwise it is the responsibility of the callback |
3139 | to invoke it (it will continue to be called until the sweep has been done, |
3281 | to invoke it (it will continue to be called until the sweep has been done, |
… | |
… | |
3160 | used). |
3302 | used). |
3161 | |
3303 | |
3162 | struct ev_loop *loop_hi = ev_default_init (0); |
3304 | struct ev_loop *loop_hi = ev_default_init (0); |
3163 | struct ev_loop *loop_lo = 0; |
3305 | struct ev_loop *loop_lo = 0; |
3164 | ev_embed embed; |
3306 | ev_embed embed; |
3165 | |
3307 | |
3166 | // see if there is a chance of getting one that works |
3308 | // see if there is a chance of getting one that works |
3167 | // (remember that a flags value of 0 means autodetection) |
3309 | // (remember that a flags value of 0 means autodetection) |
3168 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3310 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3169 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3311 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3170 | : 0; |
3312 | : 0; |
… | |
… | |
3184 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
3326 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
3185 | |
3327 | |
3186 | struct ev_loop *loop = ev_default_init (0); |
3328 | struct ev_loop *loop = ev_default_init (0); |
3187 | struct ev_loop *loop_socket = 0; |
3329 | struct ev_loop *loop_socket = 0; |
3188 | ev_embed embed; |
3330 | ev_embed embed; |
3189 | |
3331 | |
3190 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3332 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3191 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3333 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3192 | { |
3334 | { |
3193 | ev_embed_init (&embed, 0, loop_socket); |
3335 | ev_embed_init (&embed, 0, loop_socket); |
3194 | ev_embed_start (loop, &embed); |
3336 | ev_embed_start (loop, &embed); |
… | |
… | |
3202 | |
3344 | |
3203 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
3345 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
3204 | |
3346 | |
3205 | Fork watchers are called when a C<fork ()> was detected (usually because |
3347 | Fork watchers are called when a C<fork ()> was detected (usually because |
3206 | whoever is a good citizen cared to tell libev about it by calling |
3348 | whoever is a good citizen cared to tell libev about it by calling |
3207 | C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the |
3349 | C<ev_loop_fork>). The invocation is done before the event loop blocks next |
3208 | event loop blocks next and before C<ev_check> watchers are being called, |
3350 | and before C<ev_check> watchers are being called, and only in the child |
3209 | and only in the child after the fork. If whoever good citizen calling |
3351 | after the fork. If whoever good citizen calling C<ev_default_fork> cheats |
3210 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
3352 | and calls it in the wrong process, the fork handlers will be invoked, too, |
3211 | handlers will be invoked, too, of course. |
3353 | of course. |
3212 | |
3354 | |
3213 | =head3 The special problem of life after fork - how is it possible? |
3355 | =head3 The special problem of life after fork - how is it possible? |
3214 | |
3356 | |
3215 | Most uses of C<fork()> consist of forking, then some simple calls to set |
3357 | Most uses of C<fork ()> consist of forking, then some simple calls to set |
3216 | up/change the process environment, followed by a call to C<exec()>. This |
3358 | up/change the process environment, followed by a call to C<exec()>. This |
3217 | sequence should be handled by libev without any problems. |
3359 | sequence should be handled by libev without any problems. |
3218 | |
3360 | |
3219 | This changes when the application actually wants to do event handling |
3361 | This changes when the application actually wants to do event handling |
3220 | in the child, or both parent in child, in effect "continuing" after the |
3362 | in the child, or both parent in child, in effect "continuing" after the |
… | |
… | |
3309 | it by calling C<ev_async_send>, which is thread- and signal safe. |
3451 | it by calling C<ev_async_send>, which is thread- and signal safe. |
3310 | |
3452 | |
3311 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3453 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3312 | too, are asynchronous in nature, and signals, too, will be compressed |
3454 | too, are asynchronous in nature, and signals, too, will be compressed |
3313 | (i.e. the number of callback invocations may be less than the number of |
3455 | (i.e. the number of callback invocations may be less than the number of |
3314 | C<ev_async_sent> calls). In fact, you could use signal watchers as a kind |
3456 | C<ev_async_send> calls). In fact, you could use signal watchers as a kind |
3315 | of "global async watchers" by using a watcher on an otherwise unused |
3457 | of "global async watchers" by using a watcher on an otherwise unused |
3316 | signal, and C<ev_feed_signal> to signal this watcher from another thread, |
3458 | signal, and C<ev_feed_signal> to signal this watcher from another thread, |
3317 | even without knowing which loop owns the signal. |
3459 | even without knowing which loop owns the signal. |
3318 | |
3460 | |
3319 | =head3 Queueing |
3461 | =head3 Queueing |
… | |
… | |
3458 | |
3600 | |
3459 | There are some other functions of possible interest. Described. Here. Now. |
3601 | There are some other functions of possible interest. Described. Here. Now. |
3460 | |
3602 | |
3461 | =over 4 |
3603 | =over 4 |
3462 | |
3604 | |
3463 | =item ev_once (loop, int fd, int events, ev_tstamp timeout, callback) |
3605 | =item ev_once (loop, int fd, int events, ev_tstamp timeout, callback, arg) |
3464 | |
3606 | |
3465 | This function combines a simple timer and an I/O watcher, calls your |
3607 | This function combines a simple timer and an I/O watcher, calls your |
3466 | callback on whichever event happens first and automatically stops both |
3608 | callback on whichever event happens first and automatically stops both |
3467 | watchers. This is useful if you want to wait for a single event on an fd |
3609 | watchers. This is useful if you want to wait for a single event on an fd |
3468 | or timeout without having to allocate/configure/start/stop/free one or |
3610 | or timeout without having to allocate/configure/start/stop/free one or |
… | |
… | |
3610 | already been invoked. |
3752 | already been invoked. |
3611 | |
3753 | |
3612 | A common way around all these issues is to make sure that |
3754 | A common way around all these issues is to make sure that |
3613 | C<start_new_request> I<always> returns before the callback is invoked. If |
3755 | C<start_new_request> I<always> returns before the callback is invoked. If |
3614 | C<start_new_request> immediately knows the result, it can artificially |
3756 | C<start_new_request> immediately knows the result, it can artificially |
3615 | delay invoking the callback by e.g. using a C<prepare> or C<idle> watcher |
3757 | delay invoking the callback by using a C<prepare> or C<idle> watcher for |
3616 | for example, or more sneakily, by reusing an existing (stopped) watcher |
3758 | example, or more sneakily, by reusing an existing (stopped) watcher and |
3617 | and pushing it into the pending queue: |
3759 | pushing it into the pending queue: |
3618 | |
3760 | |
3619 | ev_set_cb (watcher, callback); |
3761 | ev_set_cb (watcher, callback); |
3620 | ev_feed_event (EV_A_ watcher, 0); |
3762 | ev_feed_event (EV_A_ watcher, 0); |
3621 | |
3763 | |
3622 | This way, C<start_new_request> can safely return before the callback is |
3764 | This way, C<start_new_request> can safely return before the callback is |
… | |
… | |
3630 | |
3772 | |
3631 | This brings the problem of exiting - a callback might want to finish the |
3773 | This brings the problem of exiting - a callback might want to finish the |
3632 | main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but |
3774 | main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but |
3633 | a modal "Are you sure?" dialog is still waiting), or just the nested one |
3775 | a modal "Are you sure?" dialog is still waiting), or just the nested one |
3634 | and not the main one (e.g. user clocked "Ok" in a modal dialog), or some |
3776 | and not the main one (e.g. user clocked "Ok" in a modal dialog), or some |
3635 | other combination: In these cases, C<ev_break> will not work alone. |
3777 | other combination: In these cases, a simple C<ev_break> will not work. |
3636 | |
3778 | |
3637 | The solution is to maintain "break this loop" variable for each C<ev_run> |
3779 | The solution is to maintain "break this loop" variable for each C<ev_run> |
3638 | invocation, and use a loop around C<ev_run> until the condition is |
3780 | invocation, and use a loop around C<ev_run> until the condition is |
3639 | triggered, using C<EVRUN_ONCE>: |
3781 | triggered, using C<EVRUN_ONCE>: |
3640 | |
3782 | |
… | |
… | |
3826 | called): |
3968 | called): |
3827 | |
3969 | |
3828 | void |
3970 | void |
3829 | wait_for_event (ev_watcher *w) |
3971 | wait_for_event (ev_watcher *w) |
3830 | { |
3972 | { |
3831 | ev_cb_set (w) = current_coro; |
3973 | ev_set_cb (w, current_coro); |
3832 | switch_to (libev_coro); |
3974 | switch_to (libev_coro); |
3833 | } |
3975 | } |
3834 | |
3976 | |
3835 | That basically suspends the coroutine inside C<wait_for_event> and |
3977 | That basically suspends the coroutine inside C<wait_for_event> and |
3836 | continues the libev coroutine, which, when appropriate, switches back to |
3978 | continues the libev coroutine, which, when appropriate, switches back to |
… | |
… | |
3839 | You can do similar tricks if you have, say, threads with an event queue - |
3981 | You can do similar tricks if you have, say, threads with an event queue - |
3840 | instead of storing a coroutine, you store the queue object and instead of |
3982 | instead of storing a coroutine, you store the queue object and instead of |
3841 | switching to a coroutine, you push the watcher onto the queue and notify |
3983 | switching to a coroutine, you push the watcher onto the queue and notify |
3842 | any waiters. |
3984 | any waiters. |
3843 | |
3985 | |
3844 | To embed libev, see L<EMBEDDING>, but in short, it's easiest to create two |
3986 | To embed libev, see L</EMBEDDING>, but in short, it's easiest to create two |
3845 | files, F<my_ev.h> and F<my_ev.c> that include the respective libev files: |
3987 | files, F<my_ev.h> and F<my_ev.c> that include the respective libev files: |
3846 | |
3988 | |
3847 | // my_ev.h |
3989 | // my_ev.h |
3848 | #define EV_CB_DECLARE(type) struct my_coro *cb; |
3990 | #define EV_CB_DECLARE(type) struct my_coro *cb; |
3849 | #define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb); |
3991 | #define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb) |
3850 | #include "../libev/ev.h" |
3992 | #include "../libev/ev.h" |
3851 | |
3993 | |
3852 | // my_ev.c |
3994 | // my_ev.c |
3853 | #define EV_H "my_ev.h" |
3995 | #define EV_H "my_ev.h" |
3854 | #include "../libev/ev.c" |
3996 | #include "../libev/ev.c" |
… | |
… | |
3893 | |
4035 | |
3894 | =back |
4036 | =back |
3895 | |
4037 | |
3896 | =head1 C++ SUPPORT |
4038 | =head1 C++ SUPPORT |
3897 | |
4039 | |
|
|
4040 | =head2 C API |
|
|
4041 | |
|
|
4042 | The normal C API should work fine when used from C++: both ev.h and the |
|
|
4043 | libev sources can be compiled as C++. Therefore, code that uses the C API |
|
|
4044 | will work fine. |
|
|
4045 | |
|
|
4046 | Proper exception specifications might have to be added to callbacks passed |
|
|
4047 | to libev: exceptions may be thrown only from watcher callbacks, all other |
|
|
4048 | callbacks (allocator, syserr, loop acquire/release and periodic reschedule |
|
|
4049 | callbacks) must not throw exceptions, and might need a C<noexcept> |
|
|
4050 | specification. If you have code that needs to be compiled as both C and |
|
|
4051 | C++ you can use the C<EV_NOEXCEPT> macro for this: |
|
|
4052 | |
|
|
4053 | static void |
|
|
4054 | fatal_error (const char *msg) EV_NOEXCEPT |
|
|
4055 | { |
|
|
4056 | perror (msg); |
|
|
4057 | abort (); |
|
|
4058 | } |
|
|
4059 | |
|
|
4060 | ... |
|
|
4061 | ev_set_syserr_cb (fatal_error); |
|
|
4062 | |
|
|
4063 | The only API functions that can currently throw exceptions are C<ev_run>, |
|
|
4064 | C<ev_invoke>, C<ev_invoke_pending> and C<ev_loop_destroy> (the latter |
|
|
4065 | because it runs cleanup watchers). |
|
|
4066 | |
|
|
4067 | Throwing exceptions in watcher callbacks is only supported if libev itself |
|
|
4068 | is compiled with a C++ compiler or your C and C++ environments allow |
|
|
4069 | throwing exceptions through C libraries (most do). |
|
|
4070 | |
|
|
4071 | =head2 C++ API |
|
|
4072 | |
3898 | Libev comes with some simplistic wrapper classes for C++ that mainly allow |
4073 | Libev comes with some simplistic wrapper classes for C++ that mainly allow |
3899 | you to use some convenience methods to start/stop watchers and also change |
4074 | you to use some convenience methods to start/stop watchers and also change |
3900 | the callback model to a model using method callbacks on objects. |
4075 | the callback model to a model using method callbacks on objects. |
3901 | |
4076 | |
3902 | To use it, |
4077 | To use it, |
3903 | |
4078 | |
3904 | #include <ev++.h> |
4079 | #include <ev++.h> |
3905 | |
4080 | |
3906 | This automatically includes F<ev.h> and puts all of its definitions (many |
4081 | This automatically includes F<ev.h> and puts all of its definitions (many |
3907 | of them macros) into the global namespace. All C++ specific things are |
4082 | of them macros) into the global namespace. All C++ specific things are |
3908 | put into the C<ev> namespace. It should support all the same embedding |
4083 | put into the C<ev> namespace. It should support all the same embedding |
… | |
… | |
4011 | void operator() (ev::io &w, int revents) |
4186 | void operator() (ev::io &w, int revents) |
4012 | { |
4187 | { |
4013 | ... |
4188 | ... |
4014 | } |
4189 | } |
4015 | } |
4190 | } |
4016 | |
4191 | |
4017 | myfunctor f; |
4192 | myfunctor f; |
4018 | |
4193 | |
4019 | ev::io w; |
4194 | ev::io w; |
4020 | w.set (&f); |
4195 | w.set (&f); |
4021 | |
4196 | |
… | |
… | |
4039 | Associates a different C<struct ev_loop> with this watcher. You can only |
4214 | Associates a different C<struct ev_loop> with this watcher. You can only |
4040 | do this when the watcher is inactive (and not pending either). |
4215 | do this when the watcher is inactive (and not pending either). |
4041 | |
4216 | |
4042 | =item w->set ([arguments]) |
4217 | =item w->set ([arguments]) |
4043 | |
4218 | |
4044 | Basically the same as C<ev_TYPE_set>, with the same arguments. Either this |
4219 | Basically the same as C<ev_TYPE_set> (except for C<ev::embed> watchers>), |
4045 | method or a suitable start method must be called at least once. Unlike the |
4220 | with the same arguments. Either this method or a suitable start method |
4046 | C counterpart, an active watcher gets automatically stopped and restarted |
4221 | must be called at least once. Unlike the C counterpart, an active watcher |
4047 | when reconfiguring it with this method. |
4222 | gets automatically stopped and restarted when reconfiguring it with this |
|
|
4223 | method. |
|
|
4224 | |
|
|
4225 | For C<ev::embed> watchers this method is called C<set_embed>, to avoid |
|
|
4226 | clashing with the C<set (loop)> method. |
4048 | |
4227 | |
4049 | =item w->start () |
4228 | =item w->start () |
4050 | |
4229 | |
4051 | Starts the watcher. Note that there is no C<loop> argument, as the |
4230 | Starts the watcher. Note that there is no C<loop> argument, as the |
4052 | constructor already stores the event loop. |
4231 | constructor already stores the event loop. |
… | |
… | |
4156 | |
4335 | |
4157 | Brian Maher has written a partial interface to libev for lua (at the |
4336 | Brian Maher has written a partial interface to libev for lua (at the |
4158 | time of this writing, only C<ev_io> and C<ev_timer>), to be found at |
4337 | time of this writing, only C<ev_io> and C<ev_timer>), to be found at |
4159 | L<http://github.com/brimworks/lua-ev>. |
4338 | L<http://github.com/brimworks/lua-ev>. |
4160 | |
4339 | |
|
|
4340 | =item Javascript |
|
|
4341 | |
|
|
4342 | Node.js (L<http://nodejs.org>) uses libev as the underlying event library. |
|
|
4343 | |
|
|
4344 | =item Others |
|
|
4345 | |
|
|
4346 | There are others, and I stopped counting. |
|
|
4347 | |
4161 | =back |
4348 | =back |
4162 | |
4349 | |
4163 | |
4350 | |
4164 | =head1 MACRO MAGIC |
4351 | =head1 MACRO MAGIC |
4165 | |
4352 | |
… | |
… | |
4282 | ev_vars.h |
4469 | ev_vars.h |
4283 | ev_wrap.h |
4470 | ev_wrap.h |
4284 | |
4471 | |
4285 | ev_win32.c required on win32 platforms only |
4472 | ev_win32.c required on win32 platforms only |
4286 | |
4473 | |
4287 | ev_select.c only when select backend is enabled (which is enabled by default) |
4474 | ev_select.c only when select backend is enabled |
4288 | ev_poll.c only when poll backend is enabled (disabled by default) |
4475 | ev_poll.c only when poll backend is enabled |
4289 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
4476 | ev_epoll.c only when the epoll backend is enabled |
|
|
4477 | ev_linuxaio.c only when the linux aio backend is enabled |
4290 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
4478 | ev_kqueue.c only when the kqueue backend is enabled |
4291 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
4479 | ev_port.c only when the solaris port backend is enabled |
4292 | |
4480 | |
4293 | F<ev.c> includes the backend files directly when enabled, so you only need |
4481 | F<ev.c> includes the backend files directly when enabled, so you only need |
4294 | to compile this single file. |
4482 | to compile this single file. |
4295 | |
4483 | |
4296 | =head3 LIBEVENT COMPATIBILITY API |
4484 | =head3 LIBEVENT COMPATIBILITY API |
… | |
… | |
4464 | If programs implement their own fd to handle mapping on win32, then this |
4652 | If programs implement their own fd to handle mapping on win32, then this |
4465 | macro can be used to override the C<close> function, useful to unregister |
4653 | macro can be used to override the C<close> function, useful to unregister |
4466 | file descriptors again. Note that the replacement function has to close |
4654 | file descriptors again. Note that the replacement function has to close |
4467 | the underlying OS handle. |
4655 | the underlying OS handle. |
4468 | |
4656 | |
|
|
4657 | =item EV_USE_WSASOCKET |
|
|
4658 | |
|
|
4659 | If defined to be C<1>, libev will use C<WSASocket> to create its internal |
|
|
4660 | communication socket, which works better in some environments. Otherwise, |
|
|
4661 | the normal C<socket> function will be used, which works better in other |
|
|
4662 | environments. |
|
|
4663 | |
4469 | =item EV_USE_POLL |
4664 | =item EV_USE_POLL |
4470 | |
4665 | |
4471 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
4666 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
4472 | backend. Otherwise it will be enabled on non-win32 platforms. It |
4667 | backend. Otherwise it will be enabled on non-win32 platforms. It |
4473 | takes precedence over select. |
4668 | takes precedence over select. |
… | |
… | |
4477 | If defined to be C<1>, libev will compile in support for the Linux |
4672 | If defined to be C<1>, libev will compile in support for the Linux |
4478 | C<epoll>(7) backend. Its availability will be detected at runtime, |
4673 | C<epoll>(7) backend. Its availability will be detected at runtime, |
4479 | otherwise another method will be used as fallback. This is the preferred |
4674 | otherwise another method will be used as fallback. This is the preferred |
4480 | backend for GNU/Linux systems. If undefined, it will be enabled if the |
4675 | backend for GNU/Linux systems. If undefined, it will be enabled if the |
4481 | headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
4676 | headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
|
|
4677 | |
|
|
4678 | =item EV_USE_LINUXAIO |
|
|
4679 | |
|
|
4680 | If defined to be C<1>, libev will compile in support for the Linux |
|
|
4681 | aio backend. Due to it's currenbt limitations it has to be requested |
|
|
4682 | explicitly. If undefined, it will be enabled on linux, otherwise |
|
|
4683 | disabled. |
4482 | |
4684 | |
4483 | =item EV_USE_KQUEUE |
4685 | =item EV_USE_KQUEUE |
4484 | |
4686 | |
4485 | If defined to be C<1>, libev will compile in support for the BSD style |
4687 | If defined to be C<1>, libev will compile in support for the BSD style |
4486 | C<kqueue>(2) backend. Its actual availability will be detected at runtime, |
4688 | C<kqueue>(2) backend. Its actual availability will be detected at runtime, |
… | |
… | |
4517 | different cpus (or different cpu cores). This reduces dependencies |
4719 | different cpus (or different cpu cores). This reduces dependencies |
4518 | and makes libev faster. |
4720 | and makes libev faster. |
4519 | |
4721 | |
4520 | =item EV_NO_THREADS |
4722 | =item EV_NO_THREADS |
4521 | |
4723 | |
4522 | If defined to be C<1>, libev will assume that it will never be called |
4724 | If defined to be C<1>, libev will assume that it will never be called from |
4523 | from different threads, which is a stronger assumption than C<EV_NO_SMP>, |
4725 | different threads (that includes signal handlers), which is a stronger |
4524 | above. This reduces dependencies and makes libev faster. |
4726 | assumption than C<EV_NO_SMP>, above. This reduces dependencies and makes |
|
|
4727 | libev faster. |
4525 | |
4728 | |
4526 | =item EV_ATOMIC_T |
4729 | =item EV_ATOMIC_T |
4527 | |
4730 | |
4528 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
4731 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
4529 | access is atomic and serialised with respect to other threads or signal |
4732 | access is atomic with respect to other threads or signal contexts. No |
4530 | contexts. No such type is easily found in the C language, so you can |
4733 | such type is easily found in the C language, so you can provide your own |
4531 | provide your own type that you know is safe for your purposes. It is used |
4734 | type that you know is safe for your purposes. It is used both for signal |
4532 | both for signal handler "locking" as well as for signal and thread safety |
4735 | handler "locking" as well as for signal and thread safety in C<ev_async> |
4533 | in C<ev_async> watchers. |
4736 | watchers. |
4534 | |
4737 | |
4535 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
4738 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
4536 | (from F<signal.h>), which is usually good enough on most platforms, |
4739 | (from F<signal.h>), which is usually good enough on most platforms. |
4537 | although strictly speaking using a type that also implies a memory fence |
|
|
4538 | is required. |
|
|
4539 | |
4740 | |
4540 | =item EV_H (h) |
4741 | =item EV_H (h) |
4541 | |
4742 | |
4542 | The name of the F<ev.h> header file used to include it. The default if |
4743 | The name of the F<ev.h> header file used to include it. The default if |
4543 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
4744 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
… | |
… | |
4616 | #define EV_USE_POLL 1 |
4817 | #define EV_USE_POLL 1 |
4617 | #define EV_CHILD_ENABLE 1 |
4818 | #define EV_CHILD_ENABLE 1 |
4618 | #define EV_ASYNC_ENABLE 1 |
4819 | #define EV_ASYNC_ENABLE 1 |
4619 | |
4820 | |
4620 | The actual value is a bitset, it can be a combination of the following |
4821 | The actual value is a bitset, it can be a combination of the following |
4621 | values: |
4822 | values (by default, all of these are enabled): |
4622 | |
4823 | |
4623 | =over 4 |
4824 | =over 4 |
4624 | |
4825 | |
4625 | =item C<1> - faster/larger code |
4826 | =item C<1> - faster/larger code |
4626 | |
4827 | |
… | |
… | |
4630 | code size by roughly 30% on amd64). |
4831 | code size by roughly 30% on amd64). |
4631 | |
4832 | |
4632 | When optimising for size, use of compiler flags such as C<-Os> with |
4833 | When optimising for size, use of compiler flags such as C<-Os> with |
4633 | gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of |
4834 | gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of |
4634 | assertions. |
4835 | assertions. |
|
|
4836 | |
|
|
4837 | The default is off when C<__OPTIMIZE_SIZE__> is defined by your compiler |
|
|
4838 | (e.g. gcc with C<-Os>). |
4635 | |
4839 | |
4636 | =item C<2> - faster/larger data structures |
4840 | =item C<2> - faster/larger data structures |
4637 | |
4841 | |
4638 | Replaces the small 2-heap for timer management by a faster 4-heap, larger |
4842 | Replaces the small 2-heap for timer management by a faster 4-heap, larger |
4639 | hash table sizes and so on. This will usually further increase code size |
4843 | hash table sizes and so on. This will usually further increase code size |
4640 | and can additionally have an effect on the size of data structures at |
4844 | and can additionally have an effect on the size of data structures at |
4641 | runtime. |
4845 | runtime. |
|
|
4846 | |
|
|
4847 | The default is off when C<__OPTIMIZE_SIZE__> is defined by your compiler |
|
|
4848 | (e.g. gcc with C<-Os>). |
4642 | |
4849 | |
4643 | =item C<4> - full API configuration |
4850 | =item C<4> - full API configuration |
4644 | |
4851 | |
4645 | This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and |
4852 | This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and |
4646 | enables multiplicity (C<EV_MULTIPLICITY>=1). |
4853 | enables multiplicity (C<EV_MULTIPLICITY>=1). |
… | |
… | |
4905 | default loop and triggering an C<ev_async> watcher from the default loop |
5112 | default loop and triggering an C<ev_async> watcher from the default loop |
4906 | watcher callback into the event loop interested in the signal. |
5113 | watcher callback into the event loop interested in the signal. |
4907 | |
5114 | |
4908 | =back |
5115 | =back |
4909 | |
5116 | |
4910 | See also L<THREAD LOCKING EXAMPLE>. |
5117 | See also L</THREAD LOCKING EXAMPLE>. |
4911 | |
5118 | |
4912 | =head3 COROUTINES |
5119 | =head3 COROUTINES |
4913 | |
5120 | |
4914 | Libev is very accommodating to coroutines ("cooperative threads"): |
5121 | Libev is very accommodating to coroutines ("cooperative threads"): |
4915 | libev fully supports nesting calls to its functions from different |
5122 | libev fully supports nesting calls to its functions from different |
… | |
… | |
5184 | structure (guaranteed by POSIX but not by ISO C for example), but it also |
5391 | structure (guaranteed by POSIX but not by ISO C for example), but it also |
5185 | assumes that the same (machine) code can be used to call any watcher |
5392 | assumes that the same (machine) code can be used to call any watcher |
5186 | callback: The watcher callbacks have different type signatures, but libev |
5393 | callback: The watcher callbacks have different type signatures, but libev |
5187 | calls them using an C<ev_watcher *> internally. |
5394 | calls them using an C<ev_watcher *> internally. |
5188 | |
5395 | |
|
|
5396 | =item null pointers and integer zero are represented by 0 bytes |
|
|
5397 | |
|
|
5398 | Libev uses C<memset> to initialise structs and arrays to C<0> bytes, and |
|
|
5399 | relies on this setting pointers and integers to null. |
|
|
5400 | |
5189 | =item pointer accesses must be thread-atomic |
5401 | =item pointer accesses must be thread-atomic |
5190 | |
5402 | |
5191 | Accessing a pointer value must be atomic, it must both be readable and |
5403 | Accessing a pointer value must be atomic, it must both be readable and |
5192 | writable in one piece - this is the case on all current architectures. |
5404 | writable in one piece - this is the case on all current architectures. |
5193 | |
5405 | |
… | |
… | |
5206 | thread" or will block signals process-wide, both behaviours would |
5418 | thread" or will block signals process-wide, both behaviours would |
5207 | be compatible with libev. Interaction between C<sigprocmask> and |
5419 | be compatible with libev. Interaction between C<sigprocmask> and |
5208 | C<pthread_sigmask> could complicate things, however. |
5420 | C<pthread_sigmask> could complicate things, however. |
5209 | |
5421 | |
5210 | The most portable way to handle signals is to block signals in all threads |
5422 | The most portable way to handle signals is to block signals in all threads |
5211 | except the initial one, and run the default loop in the initial thread as |
5423 | except the initial one, and run the signal handling loop in the initial |
5212 | well. |
5424 | thread as well. |
5213 | |
5425 | |
5214 | =item C<long> must be large enough for common memory allocation sizes |
5426 | =item C<long> must be large enough for common memory allocation sizes |
5215 | |
5427 | |
5216 | To improve portability and simplify its API, libev uses C<long> internally |
5428 | To improve portability and simplify its API, libev uses C<long> internally |
5217 | instead of C<size_t> when allocating its data structures. On non-POSIX |
5429 | instead of C<size_t> when allocating its data structures. On non-POSIX |
… | |
… | |
5321 | =over 4 |
5533 | =over 4 |
5322 | |
5534 | |
5323 | =item C<EV_COMPAT3> backwards compatibility mechanism |
5535 | =item C<EV_COMPAT3> backwards compatibility mechanism |
5324 | |
5536 | |
5325 | The backward compatibility mechanism can be controlled by |
5537 | The backward compatibility mechanism can be controlled by |
5326 | C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING> |
5538 | C<EV_COMPAT3>. See L</"PREPROCESSOR SYMBOLS/MACROS"> in the L</EMBEDDING> |
5327 | section. |
5539 | section. |
5328 | |
5540 | |
5329 | =item C<ev_default_destroy> and C<ev_default_fork> have been removed |
5541 | =item C<ev_default_destroy> and C<ev_default_fork> have been removed |
5330 | |
5542 | |
5331 | These calls can be replaced easily by their C<ev_loop_xxx> counterparts: |
5543 | These calls can be replaced easily by their C<ev_loop_xxx> counterparts: |
… | |
… | |
5374 | =over 4 |
5586 | =over 4 |
5375 | |
5587 | |
5376 | =item active |
5588 | =item active |
5377 | |
5589 | |
5378 | A watcher is active as long as it has been started and not yet stopped. |
5590 | A watcher is active as long as it has been started and not yet stopped. |
5379 | See L<WATCHER STATES> for details. |
5591 | See L</WATCHER STATES> for details. |
5380 | |
5592 | |
5381 | =item application |
5593 | =item application |
5382 | |
5594 | |
5383 | In this document, an application is whatever is using libev. |
5595 | In this document, an application is whatever is using libev. |
5384 | |
5596 | |
… | |
… | |
5420 | watchers and events. |
5632 | watchers and events. |
5421 | |
5633 | |
5422 | =item pending |
5634 | =item pending |
5423 | |
5635 | |
5424 | A watcher is pending as soon as the corresponding event has been |
5636 | A watcher is pending as soon as the corresponding event has been |
5425 | detected. See L<WATCHER STATES> for details. |
5637 | detected. See L</WATCHER STATES> for details. |
5426 | |
5638 | |
5427 | =item real time |
5639 | =item real time |
5428 | |
5640 | |
5429 | The physical time that is observed. It is apparently strictly monotonic :) |
5641 | The physical time that is observed. It is apparently strictly monotonic :) |
5430 | |
5642 | |