… | |
… | |
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. |
|
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309 | |
|
|
310 | It's main use is to customise signal handling in your process, especially |
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311 | in the presence of threads. For example, you could block signals |
|
|
312 | by default in all threads (and specifying C<EVFLAG_NOSIGMASK> when |
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|
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 |
… | |
… | |
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> |
|
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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. |
|
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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, |
… | |
… | |
580 | |
605 | |
581 | 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 |
582 | 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 |
583 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
608 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
584 | |
609 | |
585 | 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). |
586 | |
619 | |
587 | =back |
620 | =back |
588 | |
621 | |
589 | 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, |
590 | 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 |
… | |
… | |
2320 | |
2353 | |
2321 | 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 |
2322 | 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 |
2323 | 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. |
2324 | |
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>. |
|
|
2371 | |
2325 | =head3 Watcher-Specific Functions and Data Members |
2372 | =head3 Watcher-Specific Functions and Data Members |
2326 | |
2373 | |
2327 | =over 4 |
2374 | =over 4 |
2328 | |
2375 | |
2329 | =item ev_signal_init (ev_signal *, callback, int signum) |
2376 | =item ev_signal_init (ev_signal *, callback, int signum) |
… | |
… | |
3175 | 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. |
3176 | |
3223 | |
3177 | 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, |
3178 | too, are asynchronous in nature, and signals, too, will be compressed |
3225 | too, are asynchronous in nature, and signals, too, will be compressed |
3179 | (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 |
3180 | 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. |
3181 | |
3231 | |
3182 | 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 |
3183 | just the default loop. |
3233 | just the default loop. |
3184 | |
3234 | |
3185 | =head3 Queueing |
3235 | =head3 Queueing |
… | |
… | |
3361 | 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 |
3362 | the given events it. |
3412 | the given events it. |
3363 | |
3413 | |
3364 | =item ev_feed_signal_event (loop, int signum) |
3414 | =item ev_feed_signal_event (loop, int signum) |
3365 | |
3415 | |
3366 | 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>, |
3367 | loop!). |
3417 | which is async-safe. |
3368 | |
3418 | |
3369 | =back |
3419 | =back |
3370 | |
3420 | |
3371 | |
3421 | |
3372 | =head1 COMMON OR USEFUL IDIOMS (OR BOTH) |
3422 | =head1 COMMON OR USEFUL IDIOMS (OR BOTH) |