… | |
… | |
241 | the current system, you would need to look at C<ev_embeddable_backends () |
241 | the current system, you would need to look at C<ev_embeddable_backends () |
242 | & ev_supported_backends ()>, likewise for recommended ones. |
242 | & ev_supported_backends ()>, likewise for recommended ones. |
243 | |
243 | |
244 | See the description of C<ev_embed> watchers for more info. |
244 | See the description of C<ev_embed> watchers for more info. |
245 | |
245 | |
246 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT] |
246 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
247 | |
247 | |
248 | Sets the allocation function to use (the prototype is similar - the |
248 | Sets the allocation function to use (the prototype is similar - the |
249 | semantics are identical to the C<realloc> C89/SuS/POSIX function). It is |
249 | semantics are identical to the C<realloc> C89/SuS/POSIX function). It is |
250 | used to allocate and free memory (no surprises here). If it returns zero |
250 | used to allocate and free memory (no surprises here). If it returns zero |
251 | when memory needs to be allocated (C<size != 0>), the library might abort |
251 | when memory needs to be allocated (C<size != 0>), the library might abort |
… | |
… | |
277 | } |
277 | } |
278 | |
278 | |
279 | ... |
279 | ... |
280 | ev_set_allocator (persistent_realloc); |
280 | ev_set_allocator (persistent_realloc); |
281 | |
281 | |
282 | =item ev_set_syserr_cb (void (*cb)(const char *msg)); [NOT REENTRANT] |
282 | =item ev_set_syserr_cb (void (*cb)(const char *msg)) |
283 | |
283 | |
284 | Set the callback function to call on a retryable system call error (such |
284 | Set the callback function to call on a retryable system call error (such |
285 | as failed select, poll, epoll_wait). The message is a printable string |
285 | as failed select, poll, epoll_wait). The message is a printable string |
286 | indicating the system call or subsystem causing the problem. If this |
286 | indicating the system call or subsystem causing the problem. If this |
287 | callback is set, then libev will expect it to remedy the situation, no |
287 | callback is set, then libev will expect it to remedy the situation, no |
… | |
… | |
299 | } |
299 | } |
300 | |
300 | |
301 | ... |
301 | ... |
302 | ev_set_syserr_cb (fatal_error); |
302 | ev_set_syserr_cb (fatal_error); |
303 | |
303 | |
|
|
304 | =item ev_feed_signal (int signum) |
|
|
305 | |
|
|
306 | This function can be used to "simulate" a signal receive. It is completely |
|
|
307 | safe to call this function at any time, from any context, including signal |
|
|
308 | handlers or random threads. |
|
|
309 | |
|
|
310 | It's main use is to customise signal handling in your process, especially |
|
|
311 | in the presence of threads. For example, you could block signals |
|
|
312 | by default in all threads (and specifying C<EVFLAG_NOSIGMASK> when |
|
|
313 | creating any loops), and in one thread, use C<sigwait> or any other |
|
|
314 | mechanism to wait for signals, then "deliver" them to libev by calling |
|
|
315 | C<ev_feed_signal>. |
|
|
316 | |
304 | =back |
317 | =back |
305 | |
318 | |
306 | =head1 FUNCTIONS CONTROLLING EVENT LOOPS |
319 | =head1 FUNCTIONS CONTROLLING EVENT LOOPS |
307 | |
320 | |
308 | An event loop is described by a C<struct ev_loop *> (the C<struct> is |
321 | An event loop is described by a C<struct ev_loop *> (the C<struct> is |
… | |
… | |
355 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
368 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
356 | |
369 | |
357 | This will create and initialise a new event loop object. If the loop |
370 | This will create and initialise a new event loop object. If the loop |
358 | could not be initialised, returns false. |
371 | could not be initialised, returns false. |
359 | |
372 | |
360 | Note that this function I<is> thread-safe, and one common way to use |
373 | This function is thread-safe, and one common way to use libev with |
361 | libev with threads is indeed to create one loop per thread, and using the |
374 | threads is indeed to create one loop per thread, and using the default |
362 | default loop in the "main" or "initial" thread. |
375 | loop in the "main" or "initial" thread. |
363 | |
376 | |
364 | The flags argument can be used to specify special behaviour or specific |
377 | The flags argument can be used to specify special behaviour or specific |
365 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
378 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
366 | |
379 | |
367 | The following flags are supported: |
380 | The following flags are supported: |
… | |
… | |
402 | environment variable. |
415 | environment variable. |
403 | |
416 | |
404 | =item C<EVFLAG_NOINOTIFY> |
417 | =item C<EVFLAG_NOINOTIFY> |
405 | |
418 | |
406 | When this flag is specified, then libev will not attempt to use the |
419 | When this flag is specified, then libev will not attempt to use the |
407 | I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and |
420 | I<inotify> API for its C<ev_stat> watchers. Apart from debugging and |
408 | testing, this flag can be useful to conserve inotify file descriptors, as |
421 | testing, this flag can be useful to conserve inotify file descriptors, as |
409 | otherwise each loop using C<ev_stat> watchers consumes one inotify handle. |
422 | otherwise each loop using C<ev_stat> watchers consumes one inotify handle. |
410 | |
423 | |
411 | =item C<EVFLAG_SIGNALFD> |
424 | =item C<EVFLAG_SIGNALFD> |
412 | |
425 | |
413 | When this flag is specified, then libev will attempt to use the |
426 | When this flag is specified, then libev will attempt to use the |
414 | I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This API |
427 | I<signalfd> API for its C<ev_signal> (and C<ev_child>) watchers. This API |
415 | delivers signals synchronously, which makes it both faster and might make |
428 | delivers signals synchronously, which makes it both faster and might make |
416 | it possible to get the queued signal data. It can also simplify signal |
429 | it possible to get the queued signal data. It can also simplify signal |
417 | handling with threads, as long as you properly block signals in your |
430 | handling with threads, as long as you properly block signals in your |
418 | threads that are not interested in handling them. |
431 | threads that are not interested in handling them. |
419 | |
432 | |
420 | Signalfd will not be used by default as this changes your signal mask, and |
433 | Signalfd will not be used by default as this changes your signal mask, and |
421 | there are a lot of shoddy libraries and programs (glib's threadpool for |
434 | there are a lot of shoddy libraries and programs (glib's threadpool for |
422 | example) that can't properly initialise their signal masks. |
435 | example) that can't properly initialise their signal masks. |
|
|
436 | |
|
|
437 | =item C<EVFLAG_NOSIGMASK> |
|
|
438 | |
|
|
439 | When this flag is specified, then libev will avoid to modify the signal |
|
|
440 | mask. Specifically, this means you ahve to make sure signals are unblocked |
|
|
441 | when you want to receive them. |
|
|
442 | |
|
|
443 | This behaviour is useful when you want to do your own signal handling, or |
|
|
444 | want to handle signals only in specific threads and want to avoid libev |
|
|
445 | unblocking the signals. |
|
|
446 | |
|
|
447 | This flag's behaviour will become the default in future versions of libev. |
423 | |
448 | |
424 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
449 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
425 | |
450 | |
426 | This is your standard select(2) backend. Not I<completely> standard, as |
451 | This is your standard select(2) backend. Not I<completely> standard, as |
427 | libev tries to roll its own fd_set with no limits on the number of fds, |
452 | libev tries to roll its own fd_set with no limits on the number of fds, |
… | |
… | |
463 | epoll scales either O(1) or O(active_fds). |
488 | epoll scales either O(1) or O(active_fds). |
464 | |
489 | |
465 | The epoll mechanism deserves honorable mention as the most misdesigned |
490 | The epoll mechanism deserves honorable mention as the most misdesigned |
466 | of the more advanced event mechanisms: mere annoyances include silently |
491 | of the more advanced event mechanisms: mere annoyances include silently |
467 | dropping file descriptors, requiring a system call per change per file |
492 | dropping file descriptors, requiring a system call per change per file |
468 | descriptor (and unnecessary guessing of parameters), problems with dup and |
493 | descriptor (and unnecessary guessing of parameters), problems with dup, |
|
|
494 | returning before the timeout value, resulting in additional iterations |
|
|
495 | (and only giving 5ms accuracy while select on the same platform gives |
469 | so on. The biggest issue is fork races, however - if a program forks then |
496 | 0.1ms) and so on. The biggest issue is fork races, however - if a program |
470 | I<both> parent and child process have to recreate the epoll set, which can |
497 | forks then I<both> parent and child process have to recreate the epoll |
471 | take considerable time (one syscall per file descriptor) and is of course |
498 | set, which can take considerable time (one syscall per file descriptor) |
472 | hard to detect. |
499 | and is of course hard to detect. |
473 | |
500 | |
474 | Epoll is also notoriously buggy - embedding epoll fds I<should> work, but |
501 | Epoll is also notoriously buggy - embedding epoll fds I<should> work, but |
475 | of course I<doesn't>, and epoll just loves to report events for totally |
502 | of course I<doesn't>, and epoll just loves to report events for totally |
476 | I<different> file descriptors (even already closed ones, so one cannot |
503 | I<different> file descriptors (even already closed ones, so one cannot |
477 | even remove them from the set) than registered in the set (especially |
504 | even remove them from the set) than registered in the set (especially |
… | |
… | |
479 | employing an additional generation counter and comparing that against the |
506 | employing an additional generation counter and comparing that against the |
480 | events to filter out spurious ones, recreating the set when required. Last |
507 | events to filter out spurious ones, recreating the set when required. Last |
481 | not least, it also refuses to work with some file descriptors which work |
508 | not least, it also refuses to work with some file descriptors which work |
482 | perfectly fine with C<select> (files, many character devices...). |
509 | perfectly fine with C<select> (files, many character devices...). |
483 | |
510 | |
|
|
511 | Epoll is truly the train wreck analog among event poll mechanisms. |
|
|
512 | |
484 | While stopping, setting and starting an I/O watcher in the same iteration |
513 | While stopping, setting and starting an I/O watcher in the same iteration |
485 | will result in some caching, there is still a system call per such |
514 | will result in some caching, there is still a system call per such |
486 | incident (because the same I<file descriptor> could point to a different |
515 | incident (because the same I<file descriptor> could point to a different |
487 | I<file description> now), so its best to avoid that. Also, C<dup ()>'ed |
516 | I<file description> now), so its best to avoid that. Also, C<dup ()>'ed |
488 | file descriptors might not work very well if you register events for both |
517 | file descriptors might not work very well if you register events for both |
… | |
… | |
576 | |
605 | |
577 | Try all backends (even potentially broken ones that wouldn't be tried |
606 | Try all backends (even potentially broken ones that wouldn't be tried |
578 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
607 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
579 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
608 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
580 | |
609 | |
581 | It is definitely not recommended to use this flag. |
610 | It is definitely not recommended to use this flag, use whatever |
|
|
611 | C<ev_recommended_backends ()> returns, or simply do not specify a backend |
|
|
612 | at all. |
|
|
613 | |
|
|
614 | =item C<EVBACKEND_MASK> |
|
|
615 | |
|
|
616 | Not a backend at all, but a mask to select all backend bits from a |
|
|
617 | C<flags> value, in case you want to mask out any backends from a flags |
|
|
618 | value (e.g. when modifying the C<LIBEV_FLAGS> environment variable). |
582 | |
619 | |
583 | =back |
620 | =back |
584 | |
621 | |
585 | If one or more of the backend flags are or'ed into the flags value, |
622 | If one or more of the backend flags are or'ed into the flags value, |
586 | then only these backends will be tried (in the reverse order as listed |
623 | then only these backends will be tried (in the reverse order as listed |
… | |
… | |
615 | This function is normally used on loop objects allocated by |
652 | This function is normally used on loop objects allocated by |
616 | C<ev_loop_new>, but it can also be used on the default loop returned by |
653 | C<ev_loop_new>, but it can also be used on the default loop returned by |
617 | C<ev_default_loop>, in which case it is not thread-safe. |
654 | C<ev_default_loop>, in which case it is not thread-safe. |
618 | |
655 | |
619 | Note that it is not advisable to call this function on the default loop |
656 | Note that it is not advisable to call this function on the default loop |
620 | except in the rare occasion where you really need to free it's resources. |
657 | except in the rare occasion where you really need to free its resources. |
621 | If you need dynamically allocated loops it is better to use C<ev_loop_new> |
658 | If you need dynamically allocated loops it is better to use C<ev_loop_new> |
622 | and C<ev_loop_destroy>. |
659 | and C<ev_loop_destroy>. |
623 | |
660 | |
624 | =item ev_loop_fork (loop) |
661 | =item ev_loop_fork (loop) |
625 | |
662 | |
… | |
… | |
673 | prepare and check phases. |
710 | prepare and check phases. |
674 | |
711 | |
675 | =item unsigned int ev_depth (loop) |
712 | =item unsigned int ev_depth (loop) |
676 | |
713 | |
677 | Returns the number of times C<ev_run> was entered minus the number of |
714 | Returns the number of times C<ev_run> was entered minus the number of |
678 | times C<ev_run> was exited, in other words, the recursion depth. |
715 | times C<ev_run> was exited normally, in other words, the recursion depth. |
679 | |
716 | |
680 | Outside C<ev_run>, this number is zero. In a callback, this number is |
717 | Outside C<ev_run>, this number is zero. In a callback, this number is |
681 | C<1>, unless C<ev_run> was invoked recursively (or from another thread), |
718 | C<1>, unless C<ev_run> was invoked recursively (or from another thread), |
682 | in which case it is higher. |
719 | in which case it is higher. |
683 | |
720 | |
684 | Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread |
721 | Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread, |
685 | etc.), doesn't count as "exit" - consider this as a hint to avoid such |
722 | throwing an exception etc.), doesn't count as "exit" - consider this |
686 | ungentleman-like behaviour unless it's really convenient. |
723 | as a hint to avoid such ungentleman-like behaviour unless it's really |
|
|
724 | convenient, in which case it is fully supported. |
687 | |
725 | |
688 | =item unsigned int ev_backend (loop) |
726 | =item unsigned int ev_backend (loop) |
689 | |
727 | |
690 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
728 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
691 | use. |
729 | use. |
… | |
… | |
752 | relying on all watchers to be stopped when deciding when a program has |
790 | relying on all watchers to be stopped when deciding when a program has |
753 | finished (especially in interactive programs), but having a program |
791 | finished (especially in interactive programs), but having a program |
754 | that automatically loops as long as it has to and no longer by virtue |
792 | that automatically loops as long as it has to and no longer by virtue |
755 | of relying on its watchers stopping correctly, that is truly a thing of |
793 | of relying on its watchers stopping correctly, that is truly a thing of |
756 | beauty. |
794 | beauty. |
|
|
795 | |
|
|
796 | This function is also I<mostly> exception-safe - you can break out of |
|
|
797 | a C<ev_run> call by calling C<longjmp> in a callback, throwing a C++ |
|
|
798 | exception and so on. This does not decrement the C<ev_depth> value, nor |
|
|
799 | will it clear any outstanding C<EVBREAK_ONE> breaks. |
757 | |
800 | |
758 | A flags value of C<EVRUN_NOWAIT> will look for new events, will handle |
801 | A flags value of C<EVRUN_NOWAIT> will look for new events, will handle |
759 | those events and any already outstanding ones, but will not wait and |
802 | those events and any already outstanding ones, but will not wait and |
760 | block your process in case there are no events and will return after one |
803 | block your process in case there are no events and will return after one |
761 | iteration of the loop. This is sometimes useful to poll and handle new |
804 | iteration of the loop. This is sometimes useful to poll and handle new |
… | |
… | |
823 | Can be used to make a call to C<ev_run> return early (but only after it |
866 | Can be used to make a call to C<ev_run> return early (but only after it |
824 | has processed all outstanding events). The C<how> argument must be either |
867 | has processed all outstanding events). The C<how> argument must be either |
825 | C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or |
868 | C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or |
826 | C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return. |
869 | C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return. |
827 | |
870 | |
828 | This "break state" will be cleared when entering C<ev_run> again. |
871 | This "break state" will be cleared on the next call to C<ev_run>. |
829 | |
872 | |
830 | It is safe to call C<ev_break> from outside any C<ev_run> calls, too. |
873 | It is safe to call C<ev_break> from outside any C<ev_run> calls, too, in |
|
|
874 | which case it will have no effect. |
831 | |
875 | |
832 | =item ev_ref (loop) |
876 | =item ev_ref (loop) |
833 | |
877 | |
834 | =item ev_unref (loop) |
878 | =item ev_unref (loop) |
835 | |
879 | |
… | |
… | |
856 | running when nothing else is active. |
900 | running when nothing else is active. |
857 | |
901 | |
858 | ev_signal exitsig; |
902 | ev_signal exitsig; |
859 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
903 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
860 | ev_signal_start (loop, &exitsig); |
904 | ev_signal_start (loop, &exitsig); |
861 | evf_unref (loop); |
905 | ev_unref (loop); |
862 | |
906 | |
863 | Example: For some weird reason, unregister the above signal handler again. |
907 | Example: For some weird reason, unregister the above signal handler again. |
864 | |
908 | |
865 | ev_ref (loop); |
909 | ev_ref (loop); |
866 | ev_signal_stop (loop, &exitsig); |
910 | ev_signal_stop (loop, &exitsig); |
… | |
… | |
978 | See also the locking example in the C<THREADS> section later in this |
1022 | See also the locking example in the C<THREADS> section later in this |
979 | document. |
1023 | document. |
980 | |
1024 | |
981 | =item ev_set_userdata (loop, void *data) |
1025 | =item ev_set_userdata (loop, void *data) |
982 | |
1026 | |
983 | =item ev_userdata (loop) |
1027 | =item void *ev_userdata (loop) |
984 | |
1028 | |
985 | Set and retrieve a single C<void *> associated with a loop. When |
1029 | Set and retrieve a single C<void *> associated with a loop. When |
986 | C<ev_set_userdata> has never been called, then C<ev_userdata> returns |
1030 | C<ev_set_userdata> has never been called, then C<ev_userdata> returns |
987 | C<0.> |
1031 | C<0>. |
988 | |
1032 | |
989 | These two functions can be used to associate arbitrary data with a loop, |
1033 | These two functions can be used to associate arbitrary data with a loop, |
990 | and are intended solely for the C<invoke_pending_cb>, C<release> and |
1034 | and are intended solely for the C<invoke_pending_cb>, C<release> and |
991 | C<acquire> callbacks described above, but of course can be (ab-)used for |
1035 | C<acquire> callbacks described above, but of course can be (ab-)used for |
992 | any other purpose as well. |
1036 | any other purpose as well. |
… | |
… | |
2256 | |
2300 | |
2257 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
2301 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
2258 | |
2302 | |
2259 | Signal watchers will trigger an event when the process receives a specific |
2303 | Signal watchers will trigger an event when the process receives a specific |
2260 | signal one or more times. Even though signals are very asynchronous, libev |
2304 | signal one or more times. Even though signals are very asynchronous, libev |
2261 | will try it's best to deliver signals synchronously, i.e. as part of the |
2305 | will try its best to deliver signals synchronously, i.e. as part of the |
2262 | normal event processing, like any other event. |
2306 | normal event processing, like any other event. |
2263 | |
2307 | |
2264 | If you want signals to be delivered truly asynchronously, just use |
2308 | If you want signals to be delivered truly asynchronously, just use |
2265 | C<sigaction> as you would do without libev and forget about sharing |
2309 | C<sigaction> as you would do without libev and forget about sharing |
2266 | the signal. You can even use C<ev_async> from a signal handler to |
2310 | the signal. You can even use C<ev_async> from a signal handler to |
… | |
… | |
2308 | I<has> to modify the signal mask, at least temporarily. |
2352 | I<has> to modify the signal mask, at least temporarily. |
2309 | |
2353 | |
2310 | So I can't stress this enough: I<If you do not reset your signal mask when |
2354 | So I can't stress this enough: I<If you do not reset your signal mask when |
2311 | you expect it to be empty, you have a race condition in your code>. This |
2355 | you expect it to be empty, you have a race condition in your code>. This |
2312 | is not a libev-specific thing, this is true for most event libraries. |
2356 | is not a libev-specific thing, this is true for most event libraries. |
|
|
2357 | |
|
|
2358 | =head3 The special problem of threads signal handling |
|
|
2359 | |
|
|
2360 | POSIX threads has problematic signal handling semantics, specifically, |
|
|
2361 | a lot of functionality (sigfd, sigwait etc.) only really works if all |
|
|
2362 | threads in a process block signals, which is hard to achieve. |
|
|
2363 | |
|
|
2364 | When you want to use sigwait (or mix libev signal handling with your own |
|
|
2365 | for the same signals), you can tackle this problem by globally blocking |
|
|
2366 | all signals before creating any threads (or creating them with a fully set |
|
|
2367 | sigprocmask) and also specifying the C<EVFLAG_NOSIGMASK> when creating |
|
|
2368 | loops. Then designate one thread as "signal receiver thread" which handles |
|
|
2369 | these signals. You can pass on any signals that libev might be interested |
|
|
2370 | in by calling C<ev_feed_signal>. |
2313 | |
2371 | |
2314 | =head3 Watcher-Specific Functions and Data Members |
2372 | =head3 Watcher-Specific Functions and Data Members |
2315 | |
2373 | |
2316 | =over 4 |
2374 | =over 4 |
2317 | |
2375 | |
… | |
… | |
3164 | it by calling C<ev_async_send>, which is thread- and signal safe. |
3222 | it by calling C<ev_async_send>, which is thread- and signal safe. |
3165 | |
3223 | |
3166 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3224 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3167 | too, are asynchronous in nature, and signals, too, will be compressed |
3225 | too, are asynchronous in nature, and signals, too, will be compressed |
3168 | (i.e. the number of callback invocations may be less than the number of |
3226 | (i.e. the number of callback invocations may be less than the number of |
3169 | C<ev_async_sent> calls). |
3227 | C<ev_async_sent> calls). In fact, you could use signal watchers as a kind |
|
|
3228 | of "global async watchers" by using a watcher on an otherwise unused |
|
|
3229 | signal, and C<ev_feed_signal> to signal this watcher from another thread, |
|
|
3230 | even without knowing which loop owns the signal. |
3170 | |
3231 | |
3171 | Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not |
3232 | Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not |
3172 | just the default loop. |
3233 | just the default loop. |
3173 | |
3234 | |
3174 | =head3 Queueing |
3235 | =head3 Queueing |
… | |
… | |
3350 | Feed an event on the given fd, as if a file descriptor backend detected |
3411 | Feed an event on the given fd, as if a file descriptor backend detected |
3351 | the given events it. |
3412 | the given events it. |
3352 | |
3413 | |
3353 | =item ev_feed_signal_event (loop, int signum) |
3414 | =item ev_feed_signal_event (loop, int signum) |
3354 | |
3415 | |
3355 | Feed an event as if the given signal occurred (C<loop> must be the default |
3416 | Feed an event as if the given signal occurred. See also C<ev_feed_signal>, |
3356 | loop!). |
3417 | which is async-safe. |
|
|
3418 | |
|
|
3419 | =back |
|
|
3420 | |
|
|
3421 | |
|
|
3422 | =head1 COMMON OR USEFUL IDIOMS (OR BOTH) |
|
|
3423 | |
|
|
3424 | This section explains some common idioms that are not immediately |
|
|
3425 | obvious. Note that examples are sprinkled over the whole manual, and this |
|
|
3426 | section only contains stuff that wouldn't fit anywhere else. |
|
|
3427 | |
|
|
3428 | =over 4 |
|
|
3429 | |
|
|
3430 | =item Model/nested event loop invocations and exit conditions. |
|
|
3431 | |
|
|
3432 | Often (especially in GUI toolkits) there are places where you have |
|
|
3433 | I<modal> interaction, which is most easily implemented by recursively |
|
|
3434 | invoking C<ev_run>. |
|
|
3435 | |
|
|
3436 | This brings the problem of exiting - a callback might want to finish the |
|
|
3437 | main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but |
|
|
3438 | a modal "Are you sure?" dialog is still waiting), or just the nested one |
|
|
3439 | and not the main one (e.g. user clocked "Ok" in a modal dialog), or some |
|
|
3440 | other combination: In these cases, C<ev_break> will not work alone. |
|
|
3441 | |
|
|
3442 | The solution is to maintain "break this loop" variable for each C<ev_run> |
|
|
3443 | invocation, and use a loop around C<ev_run> until the condition is |
|
|
3444 | triggered, using C<EVRUN_ONCE>: |
|
|
3445 | |
|
|
3446 | // main loop |
|
|
3447 | int exit_main_loop = 0; |
|
|
3448 | |
|
|
3449 | while (!exit_main_loop) |
|
|
3450 | ev_run (EV_DEFAULT_ EVRUN_ONCE); |
|
|
3451 | |
|
|
3452 | // in a model watcher |
|
|
3453 | int exit_nested_loop = 0; |
|
|
3454 | |
|
|
3455 | while (!exit_nested_loop) |
|
|
3456 | ev_run (EV_A_ EVRUN_ONCE); |
|
|
3457 | |
|
|
3458 | To exit from any of these loops, just set the corresponding exit variable: |
|
|
3459 | |
|
|
3460 | // exit modal loop |
|
|
3461 | exit_nested_loop = 1; |
|
|
3462 | |
|
|
3463 | // exit main program, after modal loop is finished |
|
|
3464 | exit_main_loop = 1; |
|
|
3465 | |
|
|
3466 | // exit both |
|
|
3467 | exit_main_loop = exit_nested_loop = 1; |
3357 | |
3468 | |
3358 | =back |
3469 | =back |
3359 | |
3470 | |
3360 | |
3471 | |
3361 | =head1 LIBEVENT EMULATION |
3472 | =head1 LIBEVENT EMULATION |
3362 | |
3473 | |
3363 | Libev offers a compatibility emulation layer for libevent. It cannot |
3474 | Libev offers a compatibility emulation layer for libevent. It cannot |
3364 | emulate the internals of libevent, so here are some usage hints: |
3475 | emulate the internals of libevent, so here are some usage hints: |
3365 | |
3476 | |
3366 | =over 4 |
3477 | =over 4 |
|
|
3478 | |
|
|
3479 | =item * Only the libevent-1.4.1-beta API is being emulated. |
|
|
3480 | |
|
|
3481 | This was the newest libevent version available when libev was implemented, |
|
|
3482 | and is still mostly unchanged in 2010. |
3367 | |
3483 | |
3368 | =item * Use it by including <event.h>, as usual. |
3484 | =item * Use it by including <event.h>, as usual. |
3369 | |
3485 | |
3370 | =item * The following members are fully supported: ev_base, ev_callback, |
3486 | =item * The following members are fully supported: ev_base, ev_callback, |
3371 | ev_arg, ev_fd, ev_res, ev_events. |
3487 | ev_arg, ev_fd, ev_res, ev_events. |
… | |
… | |
3377 | =item * Priorities are not currently supported. Initialising priorities |
3493 | =item * Priorities are not currently supported. Initialising priorities |
3378 | will fail and all watchers will have the same priority, even though there |
3494 | will fail and all watchers will have the same priority, even though there |
3379 | is an ev_pri field. |
3495 | is an ev_pri field. |
3380 | |
3496 | |
3381 | =item * In libevent, the last base created gets the signals, in libev, the |
3497 | =item * In libevent, the last base created gets the signals, in libev, the |
3382 | first base created (== the default loop) gets the signals. |
3498 | base that registered the signal gets the signals. |
3383 | |
3499 | |
3384 | =item * Other members are not supported. |
3500 | =item * Other members are not supported. |
3385 | |
3501 | |
3386 | =item * The libev emulation is I<not> ABI compatible to libevent, you need |
3502 | =item * The libev emulation is I<not> ABI compatible to libevent, you need |
3387 | to use the libev header file and library. |
3503 | to use the libev header file and library. |
… | |
… | |
3406 | Care has been taken to keep the overhead low. The only data member the C++ |
3522 | Care has been taken to keep the overhead low. The only data member the C++ |
3407 | classes add (compared to plain C-style watchers) is the event loop pointer |
3523 | classes add (compared to plain C-style watchers) is the event loop pointer |
3408 | that the watcher is associated with (or no additional members at all if |
3524 | that the watcher is associated with (or no additional members at all if |
3409 | you disable C<EV_MULTIPLICITY> when embedding libev). |
3525 | you disable C<EV_MULTIPLICITY> when embedding libev). |
3410 | |
3526 | |
3411 | Currently, functions, and static and non-static member functions can be |
3527 | Currently, functions, static and non-static member functions and classes |
3412 | used as callbacks. Other types should be easy to add as long as they only |
3528 | with C<operator ()> can be used as callbacks. Other types should be easy |
3413 | need one additional pointer for context. If you need support for other |
3529 | to add as long as they only need one additional pointer for context. If |
3414 | types of functors please contact the author (preferably after implementing |
3530 | you need support for other types of functors please contact the author |
3415 | it). |
3531 | (preferably after implementing it). |
3416 | |
3532 | |
3417 | Here is a list of things available in the C<ev> namespace: |
3533 | Here is a list of things available in the C<ev> namespace: |
3418 | |
3534 | |
3419 | =over 4 |
3535 | =over 4 |
3420 | |
3536 | |