… | |
… | |
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 | Its 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: |
… | |
… | |
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, |
… | |
… | |
557 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
582 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
558 | |
583 | |
559 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
584 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
560 | it's really slow, but it still scales very well (O(active_fds)). |
585 | it's really slow, but it still scales very well (O(active_fds)). |
561 | |
586 | |
562 | Please note that Solaris event ports can deliver a lot of spurious |
|
|
563 | notifications, so you need to use non-blocking I/O or other means to avoid |
|
|
564 | blocking when no data (or space) is available. |
|
|
565 | |
|
|
566 | While this backend scales well, it requires one system call per active |
587 | While this backend scales well, it requires one system call per active |
567 | file descriptor per loop iteration. For small and medium numbers of file |
588 | file descriptor per loop iteration. For small and medium numbers of file |
568 | descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend |
589 | descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend |
569 | might perform better. |
590 | might perform better. |
570 | |
591 | |
571 | On the positive side, with the exception of the spurious readiness |
592 | On the positive side, this backend actually performed fully to |
572 | notifications, this backend actually performed fully to specification |
|
|
573 | in all tests and is fully embeddable, which is a rare feat among the |
593 | specification in all tests and is fully embeddable, which is a rare feat |
574 | OS-specific backends (I vastly prefer correctness over speed hacks). |
594 | among the OS-specific backends (I vastly prefer correctness over speed |
|
|
595 | hacks). |
|
|
596 | |
|
|
597 | On the negative side, the interface is I<bizarre> - so bizarre that |
|
|
598 | even sun itself gets it wrong in their code examples: The event polling |
|
|
599 | function sometimes returning events to the caller even though an error |
|
|
600 | occured, but with no indication whether it has done so or not (yes, it's |
|
|
601 | even documented that way) - deadly for edge-triggered interfaces where |
|
|
602 | you absolutely have to know whether an event occured or not because you |
|
|
603 | have to re-arm the watcher. |
|
|
604 | |
|
|
605 | Fortunately libev seems to be able to work around these idiocies. |
575 | |
606 | |
576 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
607 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
577 | C<EVBACKEND_POLL>. |
608 | C<EVBACKEND_POLL>. |
578 | |
609 | |
579 | =item C<EVBACKEND_ALL> |
610 | =item C<EVBACKEND_ALL> |
580 | |
611 | |
581 | Try all backends (even potentially broken ones that wouldn't be tried |
612 | Try all backends (even potentially broken ones that wouldn't be tried |
582 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
613 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
583 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
614 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
584 | |
615 | |
585 | It is definitely not recommended to use this flag. |
616 | It is definitely not recommended to use this flag, use whatever |
|
|
617 | C<ev_recommended_backends ()> returns, or simply do not specify a backend |
|
|
618 | at all. |
|
|
619 | |
|
|
620 | =item C<EVBACKEND_MASK> |
|
|
621 | |
|
|
622 | Not a backend at all, but a mask to select all backend bits from a |
|
|
623 | C<flags> value, in case you want to mask out any backends from a flags |
|
|
624 | value (e.g. when modifying the C<LIBEV_FLAGS> environment variable). |
586 | |
625 | |
587 | =back |
626 | =back |
588 | |
627 | |
589 | If one or more of the backend flags are or'ed into the flags value, |
628 | If one or more of the backend flags are or'ed into the flags value, |
590 | then only these backends will be tried (in the reverse order as listed |
629 | then only these backends will be tried (in the reverse order as listed |
… | |
… | |
677 | prepare and check phases. |
716 | prepare and check phases. |
678 | |
717 | |
679 | =item unsigned int ev_depth (loop) |
718 | =item unsigned int ev_depth (loop) |
680 | |
719 | |
681 | Returns the number of times C<ev_run> was entered minus the number of |
720 | Returns the number of times C<ev_run> was entered minus the number of |
682 | times C<ev_run> was exited, in other words, the recursion depth. |
721 | times C<ev_run> was exited normally, in other words, the recursion depth. |
683 | |
722 | |
684 | Outside C<ev_run>, this number is zero. In a callback, this number is |
723 | Outside C<ev_run>, this number is zero. In a callback, this number is |
685 | C<1>, unless C<ev_run> was invoked recursively (or from another thread), |
724 | C<1>, unless C<ev_run> was invoked recursively (or from another thread), |
686 | in which case it is higher. |
725 | in which case it is higher. |
687 | |
726 | |
688 | Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread |
727 | Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread, |
689 | etc.), doesn't count as "exit" - consider this as a hint to avoid such |
728 | throwing an exception etc.), doesn't count as "exit" - consider this |
690 | ungentleman-like behaviour unless it's really convenient. |
729 | as a hint to avoid such ungentleman-like behaviour unless it's really |
|
|
730 | convenient, in which case it is fully supported. |
691 | |
731 | |
692 | =item unsigned int ev_backend (loop) |
732 | =item unsigned int ev_backend (loop) |
693 | |
733 | |
694 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
734 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
695 | use. |
735 | use. |
… | |
… | |
756 | relying on all watchers to be stopped when deciding when a program has |
796 | relying on all watchers to be stopped when deciding when a program has |
757 | finished (especially in interactive programs), but having a program |
797 | finished (especially in interactive programs), but having a program |
758 | that automatically loops as long as it has to and no longer by virtue |
798 | that automatically loops as long as it has to and no longer by virtue |
759 | of relying on its watchers stopping correctly, that is truly a thing of |
799 | of relying on its watchers stopping correctly, that is truly a thing of |
760 | beauty. |
800 | beauty. |
|
|
801 | |
|
|
802 | This function is also I<mostly> exception-safe - you can break out of |
|
|
803 | a C<ev_run> call by calling C<longjmp> in a callback, throwing a C++ |
|
|
804 | exception and so on. This does not decrement the C<ev_depth> value, nor |
|
|
805 | will it clear any outstanding C<EVBREAK_ONE> breaks. |
761 | |
806 | |
762 | A flags value of C<EVRUN_NOWAIT> will look for new events, will handle |
807 | A flags value of C<EVRUN_NOWAIT> will look for new events, will handle |
763 | those events and any already outstanding ones, but will not wait and |
808 | those events and any already outstanding ones, but will not wait and |
764 | block your process in case there are no events and will return after one |
809 | block your process in case there are no events and will return after one |
765 | iteration of the loop. This is sometimes useful to poll and handle new |
810 | iteration of the loop. This is sometimes useful to poll and handle new |
… | |
… | |
827 | Can be used to make a call to C<ev_run> return early (but only after it |
872 | Can be used to make a call to C<ev_run> return early (but only after it |
828 | has processed all outstanding events). The C<how> argument must be either |
873 | has processed all outstanding events). The C<how> argument must be either |
829 | C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or |
874 | C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or |
830 | C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return. |
875 | C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return. |
831 | |
876 | |
832 | This "break state" will be cleared when entering C<ev_run> again. |
877 | This "break state" will be cleared on the next call to C<ev_run>. |
833 | |
878 | |
834 | It is safe to call C<ev_break> from outside any C<ev_run> calls, too. |
879 | It is safe to call C<ev_break> from outside any C<ev_run> calls, too, in |
|
|
880 | which case it will have no effect. |
835 | |
881 | |
836 | =item ev_ref (loop) |
882 | =item ev_ref (loop) |
837 | |
883 | |
838 | =item ev_unref (loop) |
884 | =item ev_unref (loop) |
839 | |
885 | |
… | |
… | |
860 | running when nothing else is active. |
906 | running when nothing else is active. |
861 | |
907 | |
862 | ev_signal exitsig; |
908 | ev_signal exitsig; |
863 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
909 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
864 | ev_signal_start (loop, &exitsig); |
910 | ev_signal_start (loop, &exitsig); |
865 | evf_unref (loop); |
911 | ev_unref (loop); |
866 | |
912 | |
867 | Example: For some weird reason, unregister the above signal handler again. |
913 | Example: For some weird reason, unregister the above signal handler again. |
868 | |
914 | |
869 | ev_ref (loop); |
915 | ev_ref (loop); |
870 | ev_signal_stop (loop, &exitsig); |
916 | ev_signal_stop (loop, &exitsig); |
… | |
… | |
982 | See also the locking example in the C<THREADS> section later in this |
1028 | See also the locking example in the C<THREADS> section later in this |
983 | document. |
1029 | document. |
984 | |
1030 | |
985 | =item ev_set_userdata (loop, void *data) |
1031 | =item ev_set_userdata (loop, void *data) |
986 | |
1032 | |
987 | =item ev_userdata (loop) |
1033 | =item void *ev_userdata (loop) |
988 | |
1034 | |
989 | Set and retrieve a single C<void *> associated with a loop. When |
1035 | Set and retrieve a single C<void *> associated with a loop. When |
990 | C<ev_set_userdata> has never been called, then C<ev_userdata> returns |
1036 | C<ev_set_userdata> has never been called, then C<ev_userdata> returns |
991 | C<0>. |
1037 | C<0>. |
992 | |
1038 | |
… | |
… | |
2312 | I<has> to modify the signal mask, at least temporarily. |
2358 | I<has> to modify the signal mask, at least temporarily. |
2313 | |
2359 | |
2314 | So I can't stress this enough: I<If you do not reset your signal mask when |
2360 | So I can't stress this enough: I<If you do not reset your signal mask when |
2315 | you expect it to be empty, you have a race condition in your code>. This |
2361 | you expect it to be empty, you have a race condition in your code>. This |
2316 | is not a libev-specific thing, this is true for most event libraries. |
2362 | is not a libev-specific thing, this is true for most event libraries. |
|
|
2363 | |
|
|
2364 | =head3 The special problem of threads signal handling |
|
|
2365 | |
|
|
2366 | POSIX threads has problematic signal handling semantics, specifically, |
|
|
2367 | a lot of functionality (sigfd, sigwait etc.) only really works if all |
|
|
2368 | threads in a process block signals, which is hard to achieve. |
|
|
2369 | |
|
|
2370 | When you want to use sigwait (or mix libev signal handling with your own |
|
|
2371 | for the same signals), you can tackle this problem by globally blocking |
|
|
2372 | all signals before creating any threads (or creating them with a fully set |
|
|
2373 | sigprocmask) and also specifying the C<EVFLAG_NOSIGMASK> when creating |
|
|
2374 | loops. Then designate one thread as "signal receiver thread" which handles |
|
|
2375 | these signals. You can pass on any signals that libev might be interested |
|
|
2376 | in by calling C<ev_feed_signal>. |
2317 | |
2377 | |
2318 | =head3 Watcher-Specific Functions and Data Members |
2378 | =head3 Watcher-Specific Functions and Data Members |
2319 | |
2379 | |
2320 | =over 4 |
2380 | =over 4 |
2321 | |
2381 | |
… | |
… | |
3168 | it by calling C<ev_async_send>, which is thread- and signal safe. |
3228 | it by calling C<ev_async_send>, which is thread- and signal safe. |
3169 | |
3229 | |
3170 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3230 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3171 | too, are asynchronous in nature, and signals, too, will be compressed |
3231 | too, are asynchronous in nature, and signals, too, will be compressed |
3172 | (i.e. the number of callback invocations may be less than the number of |
3232 | (i.e. the number of callback invocations may be less than the number of |
3173 | C<ev_async_sent> calls). |
3233 | C<ev_async_sent> calls). In fact, you could use signal watchers as a kind |
|
|
3234 | of "global async watchers" by using a watcher on an otherwise unused |
|
|
3235 | signal, and C<ev_feed_signal> to signal this watcher from another thread, |
|
|
3236 | even without knowing which loop owns the signal. |
3174 | |
3237 | |
3175 | Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not |
3238 | Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not |
3176 | just the default loop. |
3239 | just the default loop. |
3177 | |
3240 | |
3178 | =head3 Queueing |
3241 | =head3 Queueing |
… | |
… | |
3354 | Feed an event on the given fd, as if a file descriptor backend detected |
3417 | Feed an event on the given fd, as if a file descriptor backend detected |
3355 | the given events it. |
3418 | the given events it. |
3356 | |
3419 | |
3357 | =item ev_feed_signal_event (loop, int signum) |
3420 | =item ev_feed_signal_event (loop, int signum) |
3358 | |
3421 | |
3359 | Feed an event as if the given signal occurred (C<loop> must be the default |
3422 | Feed an event as if the given signal occurred. See also C<ev_feed_signal>, |
3360 | loop!). |
3423 | which is async-safe. |
|
|
3424 | |
|
|
3425 | =back |
|
|
3426 | |
|
|
3427 | |
|
|
3428 | =head1 COMMON OR USEFUL IDIOMS (OR BOTH) |
|
|
3429 | |
|
|
3430 | This section explains some common idioms that are not immediately |
|
|
3431 | obvious. Note that examples are sprinkled over the whole manual, and this |
|
|
3432 | section only contains stuff that wouldn't fit anywhere else. |
|
|
3433 | |
|
|
3434 | =over 4 |
|
|
3435 | |
|
|
3436 | =item Model/nested event loop invocations and exit conditions. |
|
|
3437 | |
|
|
3438 | Often (especially in GUI toolkits) there are places where you have |
|
|
3439 | I<modal> interaction, which is most easily implemented by recursively |
|
|
3440 | invoking C<ev_run>. |
|
|
3441 | |
|
|
3442 | This brings the problem of exiting - a callback might want to finish the |
|
|
3443 | main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but |
|
|
3444 | a modal "Are you sure?" dialog is still waiting), or just the nested one |
|
|
3445 | and not the main one (e.g. user clocked "Ok" in a modal dialog), or some |
|
|
3446 | other combination: In these cases, C<ev_break> will not work alone. |
|
|
3447 | |
|
|
3448 | The solution is to maintain "break this loop" variable for each C<ev_run> |
|
|
3449 | invocation, and use a loop around C<ev_run> until the condition is |
|
|
3450 | triggered, using C<EVRUN_ONCE>: |
|
|
3451 | |
|
|
3452 | // main loop |
|
|
3453 | int exit_main_loop = 0; |
|
|
3454 | |
|
|
3455 | while (!exit_main_loop) |
|
|
3456 | ev_run (EV_DEFAULT_ EVRUN_ONCE); |
|
|
3457 | |
|
|
3458 | // in a model watcher |
|
|
3459 | int exit_nested_loop = 0; |
|
|
3460 | |
|
|
3461 | while (!exit_nested_loop) |
|
|
3462 | ev_run (EV_A_ EVRUN_ONCE); |
|
|
3463 | |
|
|
3464 | To exit from any of these loops, just set the corresponding exit variable: |
|
|
3465 | |
|
|
3466 | // exit modal loop |
|
|
3467 | exit_nested_loop = 1; |
|
|
3468 | |
|
|
3469 | // exit main program, after modal loop is finished |
|
|
3470 | exit_main_loop = 1; |
|
|
3471 | |
|
|
3472 | // exit both |
|
|
3473 | exit_main_loop = exit_nested_loop = 1; |
3361 | |
3474 | |
3362 | =back |
3475 | =back |
3363 | |
3476 | |
3364 | |
3477 | |
3365 | =head1 LIBEVENT EMULATION |
3478 | =head1 LIBEVENT EMULATION |
3366 | |
3479 | |
3367 | Libev offers a compatibility emulation layer for libevent. It cannot |
3480 | Libev offers a compatibility emulation layer for libevent. It cannot |
3368 | emulate the internals of libevent, so here are some usage hints: |
3481 | emulate the internals of libevent, so here are some usage hints: |
3369 | |
3482 | |
3370 | =over 4 |
3483 | =over 4 |
|
|
3484 | |
|
|
3485 | =item * Only the libevent-1.4.1-beta API is being emulated. |
|
|
3486 | |
|
|
3487 | This was the newest libevent version available when libev was implemented, |
|
|
3488 | and is still mostly unchanged in 2010. |
3371 | |
3489 | |
3372 | =item * Use it by including <event.h>, as usual. |
3490 | =item * Use it by including <event.h>, as usual. |
3373 | |
3491 | |
3374 | =item * The following members are fully supported: ev_base, ev_callback, |
3492 | =item * The following members are fully supported: ev_base, ev_callback, |
3375 | ev_arg, ev_fd, ev_res, ev_events. |
3493 | ev_arg, ev_fd, ev_res, ev_events. |
… | |
… | |
3410 | Care has been taken to keep the overhead low. The only data member the C++ |
3528 | Care has been taken to keep the overhead low. The only data member the C++ |
3411 | classes add (compared to plain C-style watchers) is the event loop pointer |
3529 | classes add (compared to plain C-style watchers) is the event loop pointer |
3412 | that the watcher is associated with (or no additional members at all if |
3530 | that the watcher is associated with (or no additional members at all if |
3413 | you disable C<EV_MULTIPLICITY> when embedding libev). |
3531 | you disable C<EV_MULTIPLICITY> when embedding libev). |
3414 | |
3532 | |
3415 | Currently, functions, and static and non-static member functions can be |
3533 | Currently, functions, static and non-static member functions and classes |
3416 | used as callbacks. Other types should be easy to add as long as they only |
3534 | with C<operator ()> can be used as callbacks. Other types should be easy |
3417 | need one additional pointer for context. If you need support for other |
3535 | to add as long as they only need one additional pointer for context. If |
3418 | types of functors please contact the author (preferably after implementing |
3536 | you need support for other types of functors please contact the author |
3419 | it). |
3537 | (preferably after implementing it). |
3420 | |
3538 | |
3421 | Here is a list of things available in the C<ev> namespace: |
3539 | Here is a list of things available in the C<ev> namespace: |
3422 | |
3540 | |
3423 | =over 4 |
3541 | =over 4 |
3424 | |
3542 | |