… | |
… | |
26 | puts ("stdin ready"); |
26 | puts ("stdin ready"); |
27 | // for one-shot events, one must manually stop the watcher |
27 | // for one-shot events, one must manually stop the watcher |
28 | // with its corresponding stop function. |
28 | // with its corresponding stop function. |
29 | ev_io_stop (EV_A_ w); |
29 | ev_io_stop (EV_A_ w); |
30 | |
30 | |
31 | // this causes all nested ev_loop's to stop iterating |
31 | // this causes all nested ev_run's to stop iterating |
32 | ev_unloop (EV_A_ EVUNLOOP_ALL); |
32 | ev_break (EV_A_ EVBREAK_ALL); |
33 | } |
33 | } |
34 | |
34 | |
35 | // another callback, this time for a time-out |
35 | // another callback, this time for a time-out |
36 | static void |
36 | static void |
37 | timeout_cb (EV_P_ ev_timer *w, int revents) |
37 | timeout_cb (EV_P_ ev_timer *w, int revents) |
38 | { |
38 | { |
39 | puts ("timeout"); |
39 | puts ("timeout"); |
40 | // this causes the innermost ev_loop to stop iterating |
40 | // this causes the innermost ev_run to stop iterating |
41 | ev_unloop (EV_A_ EVUNLOOP_ONE); |
41 | ev_break (EV_A_ EVBREAK_ONE); |
42 | } |
42 | } |
43 | |
43 | |
44 | int |
44 | int |
45 | main (void) |
45 | main (void) |
46 | { |
46 | { |
… | |
… | |
56 | // simple non-repeating 5.5 second timeout |
56 | // simple non-repeating 5.5 second timeout |
57 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
57 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
58 | ev_timer_start (loop, &timeout_watcher); |
58 | ev_timer_start (loop, &timeout_watcher); |
59 | |
59 | |
60 | // now wait for events to arrive |
60 | // now wait for events to arrive |
61 | ev_loop (loop, 0); |
61 | ev_run (loop, 0); |
62 | |
62 | |
63 | // unloop was called, so exit |
63 | // unloop was called, so exit |
64 | return 0; |
64 | return 0; |
65 | } |
65 | } |
66 | |
66 | |
… | |
… | |
75 | While this document tries to be as complete as possible in documenting |
75 | While this document tries to be as complete as possible in documenting |
76 | libev, its usage and the rationale behind its design, it is not a tutorial |
76 | libev, its usage and the rationale behind its design, it is not a tutorial |
77 | on event-based programming, nor will it introduce event-based programming |
77 | on event-based programming, nor will it introduce event-based programming |
78 | with libev. |
78 | with libev. |
79 | |
79 | |
80 | Familarity with event based programming techniques in general is assumed |
80 | Familiarity with event based programming techniques in general is assumed |
81 | throughout this document. |
81 | throughout this document. |
82 | |
82 | |
83 | =head1 ABOUT LIBEV |
83 | =head1 ABOUT LIBEV |
84 | |
84 | |
85 | Libev is an event loop: you register interest in certain events (such as a |
85 | Libev is an event loop: you register interest in certain events (such as a |
… | |
… | |
98 | =head2 FEATURES |
98 | =head2 FEATURES |
99 | |
99 | |
100 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
100 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
101 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
101 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
102 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
102 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
103 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
103 | (for C<ev_stat>), Linux eventfd/signalfd (for faster and cleaner |
104 | with customised rescheduling (C<ev_periodic>), synchronous signals |
104 | inter-thread wakeup (C<ev_async>)/signal handling (C<ev_signal>)) relative |
105 | (C<ev_signal>), process status change events (C<ev_child>), and event |
105 | timers (C<ev_timer>), absolute timers with customised rescheduling |
106 | watchers dealing with the event loop mechanism itself (C<ev_idle>, |
106 | (C<ev_periodic>), synchronous signals (C<ev_signal>), process status |
107 | C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as |
107 | change events (C<ev_child>), and event watchers dealing with the event |
108 | file watchers (C<ev_stat>) and even limited support for fork events |
108 | loop mechanism itself (C<ev_idle>, C<ev_embed>, C<ev_prepare> and |
109 | (C<ev_fork>). |
109 | C<ev_check> watchers) as well as file watchers (C<ev_stat>) and even |
|
|
110 | limited support for fork events (C<ev_fork>). |
110 | |
111 | |
111 | It also is quite fast (see this |
112 | It also is quite fast (see this |
112 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
113 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
113 | for example). |
114 | for example). |
114 | |
115 | |
… | |
… | |
117 | Libev is very configurable. In this manual the default (and most common) |
118 | Libev is very configurable. In this manual the default (and most common) |
118 | configuration will be described, which supports multiple event loops. For |
119 | configuration will be described, which supports multiple event loops. For |
119 | more info about various configuration options please have a look at |
120 | more info about various configuration options please have a look at |
120 | B<EMBED> section in this manual. If libev was configured without support |
121 | B<EMBED> section in this manual. If libev was configured without support |
121 | for multiple event loops, then all functions taking an initial argument of |
122 | for multiple event loops, then all functions taking an initial argument of |
122 | name C<loop> (which is always of type C<ev_loop *>) will not have |
123 | name C<loop> (which is always of type C<struct ev_loop *>) will not have |
123 | this argument. |
124 | this argument. |
124 | |
125 | |
125 | =head2 TIME REPRESENTATION |
126 | =head2 TIME REPRESENTATION |
126 | |
127 | |
127 | Libev represents time as a single floating point number, representing |
128 | Libev represents time as a single floating point number, representing |
128 | the (fractional) number of seconds since the (POSIX) epoch (somewhere |
129 | the (fractional) number of seconds since the (POSIX) epoch (in practise |
129 | near the beginning of 1970, details are complicated, don't ask). This |
130 | somewhere near the beginning of 1970, details are complicated, don't |
130 | type is called C<ev_tstamp>, which is what you should use too. It usually |
131 | ask). This type is called C<ev_tstamp>, which is what you should use |
131 | aliases to the C<double> type in C. When you need to do any calculations |
132 | too. It usually aliases to the C<double> type in C. When you need to do |
132 | on it, you should treat it as some floating point value. Unlike the name |
133 | any calculations on it, you should treat it as some floating point value. |
|
|
134 | |
133 | component C<stamp> might indicate, it is also used for time differences |
135 | Unlike the name component C<stamp> might indicate, it is also used for |
134 | throughout libev. |
136 | time differences (e.g. delays) throughout libev. |
135 | |
137 | |
136 | =head1 ERROR HANDLING |
138 | =head1 ERROR HANDLING |
137 | |
139 | |
138 | Libev knows three classes of errors: operating system errors, usage errors |
140 | Libev knows three classes of errors: operating system errors, usage errors |
139 | and internal errors (bugs). |
141 | and internal errors (bugs). |
… | |
… | |
190 | as this indicates an incompatible change. Minor versions are usually |
192 | as this indicates an incompatible change. Minor versions are usually |
191 | compatible to older versions, so a larger minor version alone is usually |
193 | compatible to older versions, so a larger minor version alone is usually |
192 | not a problem. |
194 | not a problem. |
193 | |
195 | |
194 | Example: Make sure we haven't accidentally been linked against the wrong |
196 | Example: Make sure we haven't accidentally been linked against the wrong |
195 | version. |
197 | version (note, however, that this will not detect ABI mismatches :). |
196 | |
198 | |
197 | assert (("libev version mismatch", |
199 | assert (("libev version mismatch", |
198 | ev_version_major () == EV_VERSION_MAJOR |
200 | ev_version_major () == EV_VERSION_MAJOR |
199 | && ev_version_minor () >= EV_VERSION_MINOR)); |
201 | && ev_version_minor () >= EV_VERSION_MINOR)); |
200 | |
202 | |
… | |
… | |
290 | |
292 | |
291 | =back |
293 | =back |
292 | |
294 | |
293 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
295 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
294 | |
296 | |
295 | An event loop is described by a C<struct ev_loop *> (the C<struct> |
297 | An event loop is described by a C<struct ev_loop *> (the C<struct> is |
296 | is I<not> optional in this case, as there is also an C<ev_loop> |
298 | I<not> optional in this case unless libev 3 compatibility is disabled, as |
297 | I<function>). |
299 | libev 3 had an C<ev_loop> function colliding with the struct name). |
298 | |
300 | |
299 | The library knows two types of such loops, the I<default> loop, which |
301 | The library knows two types of such loops, the I<default> loop, which |
300 | supports signals and child events, and dynamically created loops which do |
302 | supports signals and child events, and dynamically created event loops |
301 | not. |
303 | which do not. |
302 | |
304 | |
303 | =over 4 |
305 | =over 4 |
304 | |
306 | |
305 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
307 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
306 | |
308 | |
… | |
… | |
344 | useful to try out specific backends to test their performance, or to work |
346 | useful to try out specific backends to test their performance, or to work |
345 | around bugs. |
347 | around bugs. |
346 | |
348 | |
347 | =item C<EVFLAG_FORKCHECK> |
349 | =item C<EVFLAG_FORKCHECK> |
348 | |
350 | |
349 | Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after |
351 | Instead of calling C<ev_loop_fork> manually after a fork, you can also |
350 | a fork, you can also make libev check for a fork in each iteration by |
352 | make libev check for a fork in each iteration by enabling this flag. |
351 | enabling this flag. |
|
|
352 | |
353 | |
353 | This works by calling C<getpid ()> on every iteration of the loop, |
354 | This works by calling C<getpid ()> on every iteration of the loop, |
354 | and thus this might slow down your event loop if you do a lot of loop |
355 | and thus this might slow down your event loop if you do a lot of loop |
355 | iterations and little real work, but is usually not noticeable (on my |
356 | iterations and little real work, but is usually not noticeable (on my |
356 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
357 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
… | |
… | |
362 | flag. |
363 | flag. |
363 | |
364 | |
364 | This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS> |
365 | This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS> |
365 | environment variable. |
366 | environment variable. |
366 | |
367 | |
|
|
368 | =item C<EVFLAG_NOINOTIFY> |
|
|
369 | |
|
|
370 | When this flag is specified, then libev will not attempt to use the |
|
|
371 | I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and |
|
|
372 | testing, this flag can be useful to conserve inotify file descriptors, as |
|
|
373 | otherwise each loop using C<ev_stat> watchers consumes one inotify handle. |
|
|
374 | |
|
|
375 | =item C<EVFLAG_SIGNALFD> |
|
|
376 | |
|
|
377 | When this flag is specified, then libev will attempt to use the |
|
|
378 | I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This API |
|
|
379 | delivers signals synchronously, which makes it both faster and might make |
|
|
380 | it possible to get the queued signal data. It can also simplify signal |
|
|
381 | handling with threads, as long as you properly block signals in your |
|
|
382 | threads that are not interested in handling them. |
|
|
383 | |
|
|
384 | Signalfd will not be used by default as this changes your signal mask, and |
|
|
385 | there are a lot of shoddy libraries and programs (glib's threadpool for |
|
|
386 | example) that can't properly initialise their signal masks. |
|
|
387 | |
367 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
388 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
368 | |
389 | |
369 | This is your standard select(2) backend. Not I<completely> standard, as |
390 | This is your standard select(2) backend. Not I<completely> standard, as |
370 | libev tries to roll its own fd_set with no limits on the number of fds, |
391 | libev tries to roll its own fd_set with no limits on the number of fds, |
371 | but if that fails, expect a fairly low limit on the number of fds when |
392 | but if that fails, expect a fairly low limit on the number of fds when |
… | |
… | |
394 | |
415 | |
395 | This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and |
416 | This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and |
396 | C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. |
417 | C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. |
397 | |
418 | |
398 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
419 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
|
|
420 | |
|
|
421 | Use the linux-specific epoll(7) interface (for both pre- and post-2.6.9 |
|
|
422 | kernels). |
399 | |
423 | |
400 | For few fds, this backend is a bit little slower than poll and select, |
424 | For few fds, this backend is a bit little slower than poll and select, |
401 | but it scales phenomenally better. While poll and select usually scale |
425 | but it scales phenomenally better. While poll and select usually scale |
402 | like O(total_fds) where n is the total number of fds (or the highest fd), |
426 | like O(total_fds) where n is the total number of fds (or the highest fd), |
403 | epoll scales either O(1) or O(active_fds). |
427 | epoll scales either O(1) or O(active_fds). |
… | |
… | |
415 | of course I<doesn't>, and epoll just loves to report events for totally |
439 | of course I<doesn't>, and epoll just loves to report events for totally |
416 | I<different> file descriptors (even already closed ones, so one cannot |
440 | I<different> file descriptors (even already closed ones, so one cannot |
417 | even remove them from the set) than registered in the set (especially |
441 | even remove them from the set) than registered in the set (especially |
418 | on SMP systems). Libev tries to counter these spurious notifications by |
442 | on SMP systems). Libev tries to counter these spurious notifications by |
419 | employing an additional generation counter and comparing that against the |
443 | employing an additional generation counter and comparing that against the |
420 | events to filter out spurious ones, recreating the set when required. |
444 | events to filter out spurious ones, recreating the set when required. Last |
|
|
445 | not least, it also refuses to work with some file descriptors which work |
|
|
446 | perfectly fine with C<select> (files, many character devices...). |
421 | |
447 | |
422 | While stopping, setting and starting an I/O watcher in the same iteration |
448 | While stopping, setting and starting an I/O watcher in the same iteration |
423 | will result in some caching, there is still a system call per such |
449 | will result in some caching, there is still a system call per such |
424 | incident (because the same I<file descriptor> could point to a different |
450 | incident (because the same I<file descriptor> could point to a different |
425 | I<file description> now), so its best to avoid that. Also, C<dup ()>'ed |
451 | I<file description> now), so its best to avoid that. Also, C<dup ()>'ed |
… | |
… | |
518 | |
544 | |
519 | It is definitely not recommended to use this flag. |
545 | It is definitely not recommended to use this flag. |
520 | |
546 | |
521 | =back |
547 | =back |
522 | |
548 | |
523 | If one or more of these are or'ed into the flags value, then only these |
549 | If one or more of the backend flags are or'ed into the flags value, |
524 | backends will be tried (in the reverse order as listed here). If none are |
550 | then only these backends will be tried (in the reverse order as listed |
525 | specified, all backends in C<ev_recommended_backends ()> will be tried. |
551 | here). If none are specified, all backends in C<ev_recommended_backends |
|
|
552 | ()> will be tried. |
526 | |
553 | |
527 | Example: This is the most typical usage. |
554 | Example: This is the most typical usage. |
528 | |
555 | |
529 | if (!ev_default_loop (0)) |
556 | if (!ev_default_loop (0)) |
530 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
557 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
… | |
… | |
542 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
569 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
543 | |
570 | |
544 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
571 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
545 | |
572 | |
546 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
573 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
547 | always distinct from the default loop. Unlike the default loop, it cannot |
574 | always distinct from the default loop. |
548 | handle signal and child watchers, and attempts to do so will be greeted by |
|
|
549 | undefined behaviour (or a failed assertion if assertions are enabled). |
|
|
550 | |
575 | |
551 | Note that this function I<is> thread-safe, and the recommended way to use |
576 | Note that this function I<is> thread-safe, and one common way to use |
552 | libev with threads is indeed to create one loop per thread, and using the |
577 | libev with threads is indeed to create one loop per thread, and using the |
553 | default loop in the "main" or "initial" thread. |
578 | default loop in the "main" or "initial" thread. |
554 | |
579 | |
555 | Example: Try to create a event loop that uses epoll and nothing else. |
580 | Example: Try to create a event loop that uses epoll and nothing else. |
556 | |
581 | |
… | |
… | |
558 | if (!epoller) |
583 | if (!epoller) |
559 | fatal ("no epoll found here, maybe it hides under your chair"); |
584 | fatal ("no epoll found here, maybe it hides under your chair"); |
560 | |
585 | |
561 | =item ev_default_destroy () |
586 | =item ev_default_destroy () |
562 | |
587 | |
563 | Destroys the default loop again (frees all memory and kernel state |
588 | Destroys the default loop (frees all memory and kernel state etc.). None |
564 | etc.). None of the active event watchers will be stopped in the normal |
589 | of the active event watchers will be stopped in the normal sense, so |
565 | sense, so e.g. C<ev_is_active> might still return true. It is your |
590 | e.g. C<ev_is_active> might still return true. It is your responsibility to |
566 | responsibility to either stop all watchers cleanly yourself I<before> |
591 | either stop all watchers cleanly yourself I<before> calling this function, |
567 | calling this function, or cope with the fact afterwards (which is usually |
592 | or cope with the fact afterwards (which is usually the easiest thing, you |
568 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
593 | can just ignore the watchers and/or C<free ()> them for example). |
569 | for example). |
|
|
570 | |
594 | |
571 | Note that certain global state, such as signal state (and installed signal |
595 | Note that certain global state, such as signal state (and installed signal |
572 | handlers), will not be freed by this function, and related watchers (such |
596 | handlers), will not be freed by this function, and related watchers (such |
573 | as signal and child watchers) would need to be stopped manually. |
597 | as signal and child watchers) would need to be stopped manually. |
574 | |
598 | |
575 | In general it is not advisable to call this function except in the |
599 | In general it is not advisable to call this function except in the |
576 | rare occasion where you really need to free e.g. the signal handling |
600 | rare occasion where you really need to free e.g. the signal handling |
577 | pipe fds. If you need dynamically allocated loops it is better to use |
601 | pipe fds. If you need dynamically allocated loops it is better to use |
578 | C<ev_loop_new> and C<ev_loop_destroy>). |
602 | C<ev_loop_new> and C<ev_loop_destroy>. |
579 | |
603 | |
580 | =item ev_loop_destroy (loop) |
604 | =item ev_loop_destroy (loop) |
581 | |
605 | |
582 | Like C<ev_default_destroy>, but destroys an event loop created by an |
606 | Like C<ev_default_destroy>, but destroys an event loop created by an |
583 | earlier call to C<ev_loop_new>. |
607 | earlier call to C<ev_loop_new>. |
584 | |
608 | |
585 | =item ev_default_fork () |
609 | =item ev_default_fork () |
586 | |
610 | |
587 | This function sets a flag that causes subsequent C<ev_loop> iterations |
611 | This function sets a flag that causes subsequent C<ev_run> iterations |
588 | to reinitialise the kernel state for backends that have one. Despite the |
612 | to reinitialise the kernel state for backends that have one. Despite the |
589 | name, you can call it anytime, but it makes most sense after forking, in |
613 | name, you can call it anytime, but it makes most sense after forking, in |
590 | the child process (or both child and parent, but that again makes little |
614 | the child process (or both child and parent, but that again makes little |
591 | sense). You I<must> call it in the child before using any of the libev |
615 | sense). You I<must> call it in the child before using any of the libev |
592 | functions, and it will only take effect at the next C<ev_loop> iteration. |
616 | functions, and it will only take effect at the next C<ev_run> iteration. |
|
|
617 | |
|
|
618 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
|
|
619 | a fork, I<even if you do not plan to use the loop in the parent>. This is |
|
|
620 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
|
|
621 | during fork. |
593 | |
622 | |
594 | On the other hand, you only need to call this function in the child |
623 | On the other hand, you only need to call this function in the child |
595 | process if and only if you want to use the event library in the child. If |
624 | process if and only if you want to use the event loop in the child. If |
596 | you just fork+exec, you don't have to call it at all. |
625 | you just fork+exec or create a new loop in the child, you don't have to |
|
|
626 | call it at all (in fact, C<epoll> is so badly broken that it makes a |
|
|
627 | difference, but libev will usually detect this case on its own and do a |
|
|
628 | costly reset of the backend). |
597 | |
629 | |
598 | The function itself is quite fast and it's usually not a problem to call |
630 | The function itself is quite fast and it's usually not a problem to call |
599 | it just in case after a fork. To make this easy, the function will fit in |
631 | it just in case after a fork. To make this easy, the function will fit in |
600 | quite nicely into a call to C<pthread_atfork>: |
632 | quite nicely into a call to C<pthread_atfork>: |
601 | |
633 | |
… | |
… | |
603 | |
635 | |
604 | =item ev_loop_fork (loop) |
636 | =item ev_loop_fork (loop) |
605 | |
637 | |
606 | Like C<ev_default_fork>, but acts on an event loop created by |
638 | Like C<ev_default_fork>, but acts on an event loop created by |
607 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
639 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
608 | after fork that you want to re-use in the child, and how you do this is |
640 | after fork that you want to re-use in the child, and how you keep track of |
609 | entirely your own problem. |
641 | them is entirely your own problem. |
610 | |
642 | |
611 | =item int ev_is_default_loop (loop) |
643 | =item int ev_is_default_loop (loop) |
612 | |
644 | |
613 | Returns true when the given loop is, in fact, the default loop, and false |
645 | Returns true when the given loop is, in fact, the default loop, and false |
614 | otherwise. |
646 | otherwise. |
615 | |
647 | |
616 | =item unsigned int ev_loop_count (loop) |
648 | =item unsigned int ev_iteration (loop) |
617 | |
649 | |
618 | Returns the count of loop iterations for the loop, which is identical to |
650 | Returns the current iteration count for the event loop, which is identical |
619 | the number of times libev did poll for new events. It starts at C<0> and |
651 | to the number of times libev did poll for new events. It starts at C<0> |
620 | happily wraps around with enough iterations. |
652 | and happily wraps around with enough iterations. |
621 | |
653 | |
622 | This value can sometimes be useful as a generation counter of sorts (it |
654 | This value can sometimes be useful as a generation counter of sorts (it |
623 | "ticks" the number of loop iterations), as it roughly corresponds with |
655 | "ticks" the number of loop iterations), as it roughly corresponds with |
624 | C<ev_prepare> and C<ev_check> calls. |
656 | C<ev_prepare> and C<ev_check> calls - and is incremented between the |
|
|
657 | prepare and check phases. |
|
|
658 | |
|
|
659 | =item unsigned int ev_depth (loop) |
|
|
660 | |
|
|
661 | Returns the number of times C<ev_run> was entered minus the number of |
|
|
662 | times C<ev_run> was exited, in other words, the recursion depth. |
|
|
663 | |
|
|
664 | Outside C<ev_run>, this number is zero. In a callback, this number is |
|
|
665 | C<1>, unless C<ev_run> was invoked recursively (or from another thread), |
|
|
666 | in which case it is higher. |
|
|
667 | |
|
|
668 | Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread |
|
|
669 | etc.), doesn't count as "exit" - consider this as a hint to avoid such |
|
|
670 | ungentleman-like behaviour unless it's really convenient. |
625 | |
671 | |
626 | =item unsigned int ev_backend (loop) |
672 | =item unsigned int ev_backend (loop) |
627 | |
673 | |
628 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
674 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
629 | use. |
675 | use. |
… | |
… | |
638 | |
684 | |
639 | =item ev_now_update (loop) |
685 | =item ev_now_update (loop) |
640 | |
686 | |
641 | Establishes the current time by querying the kernel, updating the time |
687 | Establishes the current time by querying the kernel, updating the time |
642 | returned by C<ev_now ()> in the progress. This is a costly operation and |
688 | returned by C<ev_now ()> in the progress. This is a costly operation and |
643 | is usually done automatically within C<ev_loop ()>. |
689 | is usually done automatically within C<ev_run ()>. |
644 | |
690 | |
645 | This function is rarely useful, but when some event callback runs for a |
691 | This function is rarely useful, but when some event callback runs for a |
646 | very long time without entering the event loop, updating libev's idea of |
692 | very long time without entering the event loop, updating libev's idea of |
647 | the current time is a good idea. |
693 | the current time is a good idea. |
648 | |
694 | |
… | |
… | |
650 | |
696 | |
651 | =item ev_suspend (loop) |
697 | =item ev_suspend (loop) |
652 | |
698 | |
653 | =item ev_resume (loop) |
699 | =item ev_resume (loop) |
654 | |
700 | |
655 | These two functions suspend and resume a loop, for use when the loop is |
701 | These two functions suspend and resume an event loop, for use when the |
656 | not used for a while and timeouts should not be processed. |
702 | loop is not used for a while and timeouts should not be processed. |
657 | |
703 | |
658 | A typical use case would be an interactive program such as a game: When |
704 | A typical use case would be an interactive program such as a game: When |
659 | the user presses C<^Z> to suspend the game and resumes it an hour later it |
705 | the user presses C<^Z> to suspend the game and resumes it an hour later it |
660 | would be best to handle timeouts as if no time had actually passed while |
706 | would be best to handle timeouts as if no time had actually passed while |
661 | the program was suspended. This can be achieved by calling C<ev_suspend> |
707 | the program was suspended. This can be achieved by calling C<ev_suspend> |
… | |
… | |
663 | C<ev_resume> directly afterwards to resume timer processing. |
709 | C<ev_resume> directly afterwards to resume timer processing. |
664 | |
710 | |
665 | Effectively, all C<ev_timer> watchers will be delayed by the time spend |
711 | Effectively, all C<ev_timer> watchers will be delayed by the time spend |
666 | between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers |
712 | between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers |
667 | will be rescheduled (that is, they will lose any events that would have |
713 | will be rescheduled (that is, they will lose any events that would have |
668 | occured while suspended). |
714 | occurred while suspended). |
669 | |
715 | |
670 | After calling C<ev_suspend> you B<must not> call I<any> function on the |
716 | After calling C<ev_suspend> you B<must not> call I<any> function on the |
671 | given loop other than C<ev_resume>, and you B<must not> call C<ev_resume> |
717 | given loop other than C<ev_resume>, and you B<must not> call C<ev_resume> |
672 | without a previous call to C<ev_suspend>. |
718 | without a previous call to C<ev_suspend>. |
673 | |
719 | |
674 | Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the |
720 | Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the |
675 | event loop time (see C<ev_now_update>). |
721 | event loop time (see C<ev_now_update>). |
676 | |
722 | |
677 | =item ev_loop (loop, int flags) |
723 | =item ev_run (loop, int flags) |
678 | |
724 | |
679 | Finally, this is it, the event handler. This function usually is called |
725 | Finally, this is it, the event handler. This function usually is called |
680 | after you initialised all your watchers and you want to start handling |
726 | after you have initialised all your watchers and you want to start |
681 | events. |
727 | handling events. It will ask the operating system for any new events, call |
|
|
728 | the watcher callbacks, an then repeat the whole process indefinitely: This |
|
|
729 | is why event loops are called I<loops>. |
682 | |
730 | |
683 | If the flags argument is specified as C<0>, it will not return until |
731 | If the flags argument is specified as C<0>, it will keep handling events |
684 | either no event watchers are active anymore or C<ev_unloop> was called. |
732 | until either no event watchers are active anymore or C<ev_break> was |
|
|
733 | called. |
685 | |
734 | |
686 | Please note that an explicit C<ev_unloop> is usually better than |
735 | Please note that an explicit C<ev_break> is usually better than |
687 | relying on all watchers to be stopped when deciding when a program has |
736 | relying on all watchers to be stopped when deciding when a program has |
688 | finished (especially in interactive programs), but having a program |
737 | finished (especially in interactive programs), but having a program |
689 | that automatically loops as long as it has to and no longer by virtue |
738 | that automatically loops as long as it has to and no longer by virtue |
690 | of relying on its watchers stopping correctly, that is truly a thing of |
739 | of relying on its watchers stopping correctly, that is truly a thing of |
691 | beauty. |
740 | beauty. |
692 | |
741 | |
693 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
742 | A flags value of C<EVRUN_NOWAIT> will look for new events, will handle |
694 | those events and any already outstanding ones, but will not block your |
743 | those events and any already outstanding ones, but will not wait and |
695 | process in case there are no events and will return after one iteration of |
744 | block your process in case there are no events and will return after one |
696 | the loop. |
745 | iteration of the loop. This is sometimes useful to poll and handle new |
|
|
746 | events while doing lengthy calculations, to keep the program responsive. |
697 | |
747 | |
698 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
748 | A flags value of C<EVRUN_ONCE> will look for new events (waiting if |
699 | necessary) and will handle those and any already outstanding ones. It |
749 | necessary) and will handle those and any already outstanding ones. It |
700 | will block your process until at least one new event arrives (which could |
750 | will block your process until at least one new event arrives (which could |
701 | be an event internal to libev itself, so there is no guarantee that a |
751 | be an event internal to libev itself, so there is no guarantee that a |
702 | user-registered callback will be called), and will return after one |
752 | user-registered callback will be called), and will return after one |
703 | iteration of the loop. |
753 | iteration of the loop. |
704 | |
754 | |
705 | This is useful if you are waiting for some external event in conjunction |
755 | This is useful if you are waiting for some external event in conjunction |
706 | with something not expressible using other libev watchers (i.e. "roll your |
756 | with something not expressible using other libev watchers (i.e. "roll your |
707 | own C<ev_loop>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is |
757 | own C<ev_run>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is |
708 | usually a better approach for this kind of thing. |
758 | usually a better approach for this kind of thing. |
709 | |
759 | |
710 | Here are the gory details of what C<ev_loop> does: |
760 | Here are the gory details of what C<ev_run> does: |
711 | |
761 | |
|
|
762 | - Increment loop depth. |
|
|
763 | - Reset the ev_break status. |
712 | - Before the first iteration, call any pending watchers. |
764 | - Before the first iteration, call any pending watchers. |
|
|
765 | LOOP: |
713 | * If EVFLAG_FORKCHECK was used, check for a fork. |
766 | - If EVFLAG_FORKCHECK was used, check for a fork. |
714 | - If a fork was detected (by any means), queue and call all fork watchers. |
767 | - If a fork was detected (by any means), queue and call all fork watchers. |
715 | - Queue and call all prepare watchers. |
768 | - Queue and call all prepare watchers. |
|
|
769 | - If ev_break was called, goto FINISH. |
716 | - If we have been forked, detach and recreate the kernel state |
770 | - If we have been forked, detach and recreate the kernel state |
717 | as to not disturb the other process. |
771 | as to not disturb the other process. |
718 | - Update the kernel state with all outstanding changes. |
772 | - Update the kernel state with all outstanding changes. |
719 | - Update the "event loop time" (ev_now ()). |
773 | - Update the "event loop time" (ev_now ()). |
720 | - Calculate for how long to sleep or block, if at all |
774 | - Calculate for how long to sleep or block, if at all |
721 | (active idle watchers, EVLOOP_NONBLOCK or not having |
775 | (active idle watchers, EVRUN_NOWAIT or not having |
722 | any active watchers at all will result in not sleeping). |
776 | any active watchers at all will result in not sleeping). |
723 | - Sleep if the I/O and timer collect interval say so. |
777 | - Sleep if the I/O and timer collect interval say so. |
|
|
778 | - Increment loop iteration counter. |
724 | - Block the process, waiting for any events. |
779 | - Block the process, waiting for any events. |
725 | - Queue all outstanding I/O (fd) events. |
780 | - Queue all outstanding I/O (fd) events. |
726 | - Update the "event loop time" (ev_now ()), and do time jump adjustments. |
781 | - Update the "event loop time" (ev_now ()), and do time jump adjustments. |
727 | - Queue all expired timers. |
782 | - Queue all expired timers. |
728 | - Queue all expired periodics. |
783 | - Queue all expired periodics. |
729 | - Unless any events are pending now, queue all idle watchers. |
784 | - Queue all idle watchers with priority higher than that of pending events. |
730 | - Queue all check watchers. |
785 | - Queue all check watchers. |
731 | - Call all queued watchers in reverse order (i.e. check watchers first). |
786 | - Call all queued watchers in reverse order (i.e. check watchers first). |
732 | Signals and child watchers are implemented as I/O watchers, and will |
787 | Signals and child watchers are implemented as I/O watchers, and will |
733 | be handled here by queueing them when their watcher gets executed. |
788 | be handled here by queueing them when their watcher gets executed. |
734 | - If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
789 | - If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT |
735 | were used, or there are no active watchers, return, otherwise |
790 | were used, or there are no active watchers, goto FINISH, otherwise |
736 | continue with step *. |
791 | continue with step LOOP. |
|
|
792 | FINISH: |
|
|
793 | - Reset the ev_break status iff it was EVBREAK_ONE. |
|
|
794 | - Decrement the loop depth. |
|
|
795 | - Return. |
737 | |
796 | |
738 | Example: Queue some jobs and then loop until no events are outstanding |
797 | Example: Queue some jobs and then loop until no events are outstanding |
739 | anymore. |
798 | anymore. |
740 | |
799 | |
741 | ... queue jobs here, make sure they register event watchers as long |
800 | ... queue jobs here, make sure they register event watchers as long |
742 | ... as they still have work to do (even an idle watcher will do..) |
801 | ... as they still have work to do (even an idle watcher will do..) |
743 | ev_loop (my_loop, 0); |
802 | ev_run (my_loop, 0); |
744 | ... jobs done or somebody called unloop. yeah! |
803 | ... jobs done or somebody called unloop. yeah! |
745 | |
804 | |
746 | =item ev_unloop (loop, how) |
805 | =item ev_break (loop, how) |
747 | |
806 | |
748 | Can be used to make a call to C<ev_loop> return early (but only after it |
807 | Can be used to make a call to C<ev_run> return early (but only after it |
749 | has processed all outstanding events). The C<how> argument must be either |
808 | has processed all outstanding events). The C<how> argument must be either |
750 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
809 | C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or |
751 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
810 | C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return. |
752 | |
811 | |
753 | This "unloop state" will be cleared when entering C<ev_loop> again. |
812 | This "unloop state" will be cleared when entering C<ev_run> again. |
754 | |
813 | |
755 | It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls. |
814 | It is safe to call C<ev_break> from outside any C<ev_run> calls. ##TODO## |
756 | |
815 | |
757 | =item ev_ref (loop) |
816 | =item ev_ref (loop) |
758 | |
817 | |
759 | =item ev_unref (loop) |
818 | =item ev_unref (loop) |
760 | |
819 | |
761 | Ref/unref can be used to add or remove a reference count on the event |
820 | Ref/unref can be used to add or remove a reference count on the event |
762 | loop: Every watcher keeps one reference, and as long as the reference |
821 | loop: Every watcher keeps one reference, and as long as the reference |
763 | count is nonzero, C<ev_loop> will not return on its own. |
822 | count is nonzero, C<ev_run> will not return on its own. |
764 | |
823 | |
765 | If you have a watcher you never unregister that should not keep C<ev_loop> |
824 | This is useful when you have a watcher that you never intend to |
766 | from returning, call ev_unref() after starting, and ev_ref() before |
825 | unregister, but that nevertheless should not keep C<ev_run> from |
|
|
826 | returning. In such a case, call C<ev_unref> after starting, and C<ev_ref> |
767 | stopping it. |
827 | before stopping it. |
768 | |
828 | |
769 | As an example, libev itself uses this for its internal signal pipe: It |
829 | As an example, libev itself uses this for its internal signal pipe: It |
770 | is not visible to the libev user and should not keep C<ev_loop> from |
830 | is not visible to the libev user and should not keep C<ev_run> from |
771 | exiting if no event watchers registered by it are active. It is also an |
831 | exiting if no event watchers registered by it are active. It is also an |
772 | excellent way to do this for generic recurring timers or from within |
832 | excellent way to do this for generic recurring timers or from within |
773 | third-party libraries. Just remember to I<unref after start> and I<ref |
833 | third-party libraries. Just remember to I<unref after start> and I<ref |
774 | before stop> (but only if the watcher wasn't active before, or was active |
834 | before stop> (but only if the watcher wasn't active before, or was active |
775 | before, respectively. Note also that libev might stop watchers itself |
835 | before, respectively. Note also that libev might stop watchers itself |
776 | (e.g. non-repeating timers) in which case you have to C<ev_ref> |
836 | (e.g. non-repeating timers) in which case you have to C<ev_ref> |
777 | in the callback). |
837 | in the callback). |
778 | |
838 | |
779 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
839 | Example: Create a signal watcher, but keep it from keeping C<ev_run> |
780 | running when nothing else is active. |
840 | running when nothing else is active. |
781 | |
841 | |
782 | ev_signal exitsig; |
842 | ev_signal exitsig; |
783 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
843 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
784 | ev_signal_start (loop, &exitsig); |
844 | ev_signal_start (loop, &exitsig); |
… | |
… | |
811 | |
871 | |
812 | By setting a higher I<io collect interval> you allow libev to spend more |
872 | By setting a higher I<io collect interval> you allow libev to spend more |
813 | time collecting I/O events, so you can handle more events per iteration, |
873 | time collecting I/O events, so you can handle more events per iteration, |
814 | at the cost of increasing latency. Timeouts (both C<ev_periodic> and |
874 | at the cost of increasing latency. Timeouts (both C<ev_periodic> and |
815 | C<ev_timer>) will be not affected. Setting this to a non-null value will |
875 | C<ev_timer>) will be not affected. Setting this to a non-null value will |
816 | introduce an additional C<ev_sleep ()> call into most loop iterations. |
876 | introduce an additional C<ev_sleep ()> call into most loop iterations. The |
|
|
877 | sleep time ensures that libev will not poll for I/O events more often then |
|
|
878 | once per this interval, on average. |
817 | |
879 | |
818 | Likewise, by setting a higher I<timeout collect interval> you allow libev |
880 | Likewise, by setting a higher I<timeout collect interval> you allow libev |
819 | to spend more time collecting timeouts, at the expense of increased |
881 | to spend more time collecting timeouts, at the expense of increased |
820 | latency/jitter/inexactness (the watcher callback will be called |
882 | latency/jitter/inexactness (the watcher callback will be called |
821 | later). C<ev_io> watchers will not be affected. Setting this to a non-null |
883 | later). C<ev_io> watchers will not be affected. Setting this to a non-null |
… | |
… | |
823 | |
885 | |
824 | Many (busy) programs can usually benefit by setting the I/O collect |
886 | Many (busy) programs can usually benefit by setting the I/O collect |
825 | interval to a value near C<0.1> or so, which is often enough for |
887 | interval to a value near C<0.1> or so, which is often enough for |
826 | interactive servers (of course not for games), likewise for timeouts. It |
888 | interactive servers (of course not for games), likewise for timeouts. It |
827 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
889 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
828 | as this approaches the timing granularity of most systems. |
890 | as this approaches the timing granularity of most systems. Note that if |
|
|
891 | you do transactions with the outside world and you can't increase the |
|
|
892 | parallelity, then this setting will limit your transaction rate (if you |
|
|
893 | need to poll once per transaction and the I/O collect interval is 0.01, |
|
|
894 | then you can't do more than 100 transactions per second). |
829 | |
895 | |
830 | Setting the I<timeout collect interval> can improve the opportunity for |
896 | Setting the I<timeout collect interval> can improve the opportunity for |
831 | saving power, as the program will "bundle" timer callback invocations that |
897 | saving power, as the program will "bundle" timer callback invocations that |
832 | are "near" in time together, by delaying some, thus reducing the number of |
898 | are "near" in time together, by delaying some, thus reducing the number of |
833 | times the process sleeps and wakes up again. Another useful technique to |
899 | times the process sleeps and wakes up again. Another useful technique to |
834 | reduce iterations/wake-ups is to use C<ev_periodic> watchers and make sure |
900 | reduce iterations/wake-ups is to use C<ev_periodic> watchers and make sure |
835 | they fire on, say, one-second boundaries only. |
901 | they fire on, say, one-second boundaries only. |
836 | |
902 | |
|
|
903 | Example: we only need 0.1s timeout granularity, and we wish not to poll |
|
|
904 | more often than 100 times per second: |
|
|
905 | |
|
|
906 | ev_set_timeout_collect_interval (EV_DEFAULT_UC_ 0.1); |
|
|
907 | ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
|
|
908 | |
|
|
909 | =item ev_invoke_pending (loop) |
|
|
910 | |
|
|
911 | This call will simply invoke all pending watchers while resetting their |
|
|
912 | pending state. Normally, C<ev_run> does this automatically when required, |
|
|
913 | but when overriding the invoke callback this call comes handy. This |
|
|
914 | function can be invoked from a watcher - this can be useful for example |
|
|
915 | when you want to do some lengthy calculation and want to pass further |
|
|
916 | event handling to another thread (you still have to make sure only one |
|
|
917 | thread executes within C<ev_invoke_pending> or C<ev_run> of course). |
|
|
918 | |
|
|
919 | =item int ev_pending_count (loop) |
|
|
920 | |
|
|
921 | Returns the number of pending watchers - zero indicates that no watchers |
|
|
922 | are pending. |
|
|
923 | |
|
|
924 | =item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P)) |
|
|
925 | |
|
|
926 | This overrides the invoke pending functionality of the loop: Instead of |
|
|
927 | invoking all pending watchers when there are any, C<ev_run> will call |
|
|
928 | this callback instead. This is useful, for example, when you want to |
|
|
929 | invoke the actual watchers inside another context (another thread etc.). |
|
|
930 | |
|
|
931 | If you want to reset the callback, use C<ev_invoke_pending> as new |
|
|
932 | callback. |
|
|
933 | |
|
|
934 | =item ev_set_loop_release_cb (loop, void (*release)(EV_P), void (*acquire)(EV_P)) |
|
|
935 | |
|
|
936 | Sometimes you want to share the same loop between multiple threads. This |
|
|
937 | can be done relatively simply by putting mutex_lock/unlock calls around |
|
|
938 | each call to a libev function. |
|
|
939 | |
|
|
940 | However, C<ev_run> can run an indefinite time, so it is not feasible |
|
|
941 | to wait for it to return. One way around this is to wake up the event |
|
|
942 | loop via C<ev_break> and C<av_async_send>, another way is to set these |
|
|
943 | I<release> and I<acquire> callbacks on the loop. |
|
|
944 | |
|
|
945 | When set, then C<release> will be called just before the thread is |
|
|
946 | suspended waiting for new events, and C<acquire> is called just |
|
|
947 | afterwards. |
|
|
948 | |
|
|
949 | Ideally, C<release> will just call your mutex_unlock function, and |
|
|
950 | C<acquire> will just call the mutex_lock function again. |
|
|
951 | |
|
|
952 | While event loop modifications are allowed between invocations of |
|
|
953 | C<release> and C<acquire> (that's their only purpose after all), no |
|
|
954 | modifications done will affect the event loop, i.e. adding watchers will |
|
|
955 | have no effect on the set of file descriptors being watched, or the time |
|
|
956 | waited. Use an C<ev_async> watcher to wake up C<ev_run> when you want it |
|
|
957 | to take note of any changes you made. |
|
|
958 | |
|
|
959 | In theory, threads executing C<ev_run> will be async-cancel safe between |
|
|
960 | invocations of C<release> and C<acquire>. |
|
|
961 | |
|
|
962 | See also the locking example in the C<THREADS> section later in this |
|
|
963 | document. |
|
|
964 | |
|
|
965 | =item ev_set_userdata (loop, void *data) |
|
|
966 | |
|
|
967 | =item ev_userdata (loop) |
|
|
968 | |
|
|
969 | Set and retrieve a single C<void *> associated with a loop. When |
|
|
970 | C<ev_set_userdata> has never been called, then C<ev_userdata> returns |
|
|
971 | C<0.> |
|
|
972 | |
|
|
973 | These two functions can be used to associate arbitrary data with a loop, |
|
|
974 | and are intended solely for the C<invoke_pending_cb>, C<release> and |
|
|
975 | C<acquire> callbacks described above, but of course can be (ab-)used for |
|
|
976 | any other purpose as well. |
|
|
977 | |
837 | =item ev_loop_verify (loop) |
978 | =item ev_verify (loop) |
838 | |
979 | |
839 | This function only does something when C<EV_VERIFY> support has been |
980 | This function only does something when C<EV_VERIFY> support has been |
840 | compiled in, which is the default for non-minimal builds. It tries to go |
981 | compiled in, which is the default for non-minimal builds. It tries to go |
841 | through all internal structures and checks them for validity. If anything |
982 | through all internal structures and checks them for validity. If anything |
842 | is found to be inconsistent, it will print an error message to standard |
983 | is found to be inconsistent, it will print an error message to standard |
… | |
… | |
853 | |
994 | |
854 | In the following description, uppercase C<TYPE> in names stands for the |
995 | In the following description, uppercase C<TYPE> in names stands for the |
855 | watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer |
996 | watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer |
856 | watchers and C<ev_io_start> for I/O watchers. |
997 | watchers and C<ev_io_start> for I/O watchers. |
857 | |
998 | |
858 | A watcher is a structure that you create and register to record your |
999 | A watcher is an opaque structure that you allocate and register to record |
859 | interest in some event. For instance, if you want to wait for STDIN to |
1000 | your interest in some event. To make a concrete example, imagine you want |
860 | become readable, you would create an C<ev_io> watcher for that: |
1001 | to wait for STDIN to become readable, you would create an C<ev_io> watcher |
|
|
1002 | for that: |
861 | |
1003 | |
862 | static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
1004 | static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
863 | { |
1005 | { |
864 | ev_io_stop (w); |
1006 | ev_io_stop (w); |
865 | ev_unloop (loop, EVUNLOOP_ALL); |
1007 | ev_break (loop, EVBREAK_ALL); |
866 | } |
1008 | } |
867 | |
1009 | |
868 | struct ev_loop *loop = ev_default_loop (0); |
1010 | struct ev_loop *loop = ev_default_loop (0); |
869 | |
1011 | |
870 | ev_io stdin_watcher; |
1012 | ev_io stdin_watcher; |
871 | |
1013 | |
872 | ev_init (&stdin_watcher, my_cb); |
1014 | ev_init (&stdin_watcher, my_cb); |
873 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
1015 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
874 | ev_io_start (loop, &stdin_watcher); |
1016 | ev_io_start (loop, &stdin_watcher); |
875 | |
1017 | |
876 | ev_loop (loop, 0); |
1018 | ev_run (loop, 0); |
877 | |
1019 | |
878 | As you can see, you are responsible for allocating the memory for your |
1020 | As you can see, you are responsible for allocating the memory for your |
879 | watcher structures (and it is I<usually> a bad idea to do this on the |
1021 | watcher structures (and it is I<usually> a bad idea to do this on the |
880 | stack). |
1022 | stack). |
881 | |
1023 | |
882 | Each watcher has an associated watcher structure (called C<struct ev_TYPE> |
1024 | Each watcher has an associated watcher structure (called C<struct ev_TYPE> |
883 | or simply C<ev_TYPE>, as typedefs are provided for all watcher structs). |
1025 | or simply C<ev_TYPE>, as typedefs are provided for all watcher structs). |
884 | |
1026 | |
885 | Each watcher structure must be initialised by a call to C<ev_init |
1027 | Each watcher structure must be initialised by a call to C<ev_init (watcher |
886 | (watcher *, callback)>, which expects a callback to be provided. This |
1028 | *, callback)>, which expects a callback to be provided. This callback is |
887 | callback gets invoked each time the event occurs (or, in the case of I/O |
1029 | invoked each time the event occurs (or, in the case of I/O watchers, each |
888 | watchers, each time the event loop detects that the file descriptor given |
1030 | time the event loop detects that the file descriptor given is readable |
889 | is readable and/or writable). |
1031 | and/or writable). |
890 | |
1032 | |
891 | Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >> |
1033 | Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >> |
892 | macro to configure it, with arguments specific to the watcher type. There |
1034 | macro to configure it, with arguments specific to the watcher type. There |
893 | is also a macro to combine initialisation and setting in one call: C<< |
1035 | is also a macro to combine initialisation and setting in one call: C<< |
894 | ev_TYPE_init (watcher *, callback, ...) >>. |
1036 | ev_TYPE_init (watcher *, callback, ...) >>. |
… | |
… | |
917 | =item C<EV_WRITE> |
1059 | =item C<EV_WRITE> |
918 | |
1060 | |
919 | The file descriptor in the C<ev_io> watcher has become readable and/or |
1061 | The file descriptor in the C<ev_io> watcher has become readable and/or |
920 | writable. |
1062 | writable. |
921 | |
1063 | |
922 | =item C<EV_TIMEOUT> |
1064 | =item C<EV_TIMER> |
923 | |
1065 | |
924 | The C<ev_timer> watcher has timed out. |
1066 | The C<ev_timer> watcher has timed out. |
925 | |
1067 | |
926 | =item C<EV_PERIODIC> |
1068 | =item C<EV_PERIODIC> |
927 | |
1069 | |
… | |
… | |
945 | |
1087 | |
946 | =item C<EV_PREPARE> |
1088 | =item C<EV_PREPARE> |
947 | |
1089 | |
948 | =item C<EV_CHECK> |
1090 | =item C<EV_CHECK> |
949 | |
1091 | |
950 | All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts |
1092 | All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts |
951 | to gather new events, and all C<ev_check> watchers are invoked just after |
1093 | to gather new events, and all C<ev_check> watchers are invoked just after |
952 | C<ev_loop> has gathered them, but before it invokes any callbacks for any |
1094 | C<ev_run> has gathered them, but before it invokes any callbacks for any |
953 | received events. Callbacks of both watcher types can start and stop as |
1095 | received events. Callbacks of both watcher types can start and stop as |
954 | many watchers as they want, and all of them will be taken into account |
1096 | many watchers as they want, and all of them will be taken into account |
955 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
1097 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
956 | C<ev_loop> from blocking). |
1098 | C<ev_run> from blocking). |
957 | |
1099 | |
958 | =item C<EV_EMBED> |
1100 | =item C<EV_EMBED> |
959 | |
1101 | |
960 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1102 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
961 | |
1103 | |
… | |
… | |
992 | programs, though, as the fd could already be closed and reused for another |
1134 | programs, though, as the fd could already be closed and reused for another |
993 | thing, so beware. |
1135 | thing, so beware. |
994 | |
1136 | |
995 | =back |
1137 | =back |
996 | |
1138 | |
|
|
1139 | =head2 WATCHER STATES |
|
|
1140 | |
|
|
1141 | There are various watcher states mentioned throughout this manual - |
|
|
1142 | active, pending and so on. In this section these states and the rules to |
|
|
1143 | transition between them will be described in more detail - and while these |
|
|
1144 | rules might look complicated, they usually do "the right thing". |
|
|
1145 | |
|
|
1146 | =over 4 |
|
|
1147 | |
|
|
1148 | =item initialiased |
|
|
1149 | |
|
|
1150 | Before a watcher can be registered with the event looop it has to be |
|
|
1151 | initialised. This can be done with a call to C<ev_TYPE_init>, or calls to |
|
|
1152 | C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
|
|
1153 | |
|
|
1154 | In this state it is simply some block of memory that is suitable for use |
|
|
1155 | in an event loop. It can be moved around, freed, reused etc. at will. |
|
|
1156 | |
|
|
1157 | =item started/running/active |
|
|
1158 | |
|
|
1159 | Once a watcher has been started with a call to C<ev_TYPE_start> it becomes |
|
|
1160 | property of the event loop, and is actively waiting for events. While in |
|
|
1161 | this state it cannot be accessed (except in a few documented ways), moved, |
|
|
1162 | freed or anything else - the only legal thing is to keep a pointer to it, |
|
|
1163 | and call libev functions on it that are documented to work on active watchers. |
|
|
1164 | |
|
|
1165 | =item pending |
|
|
1166 | |
|
|
1167 | If a watcher is active and libev determines that an event it is interested |
|
|
1168 | in has occurred (such as a timer expiring), it will become pending. It will |
|
|
1169 | stay in this pending state until either it is stopped or its callback is |
|
|
1170 | about to be invoked, so it is not normally pending inside the watcher |
|
|
1171 | callback. |
|
|
1172 | |
|
|
1173 | The watcher might or might not be active while it is pending (for example, |
|
|
1174 | an expired non-repeating timer can be pending but no longer active). If it |
|
|
1175 | is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>), |
|
|
1176 | but it is still property of the event loop at this time, so cannot be |
|
|
1177 | moved, freed or reused. And if it is active the rules described in the |
|
|
1178 | previous item still apply. |
|
|
1179 | |
|
|
1180 | It is also possible to feed an event on a watcher that is not active (e.g. |
|
|
1181 | via C<ev_feed_event>), in which case it becomes pending without being |
|
|
1182 | active. |
|
|
1183 | |
|
|
1184 | =item stopped |
|
|
1185 | |
|
|
1186 | A watcher can be stopped implicitly by libev (in which case it might still |
|
|
1187 | be pending), or explicitly by calling its C<ev_TYPE_stop> function. The |
|
|
1188 | latter will clear any pending state the watcher might be in, regardless |
|
|
1189 | of whether it was active or not, so stopping a watcher explicitly before |
|
|
1190 | freeing it is often a good idea. |
|
|
1191 | |
|
|
1192 | While stopped (and not pending) the watcher is essentially in the |
|
|
1193 | initialised state, that is it can be reused, moved, modified in any way |
|
|
1194 | you wish. |
|
|
1195 | |
|
|
1196 | =back |
|
|
1197 | |
997 | =head2 GENERIC WATCHER FUNCTIONS |
1198 | =head2 GENERIC WATCHER FUNCTIONS |
998 | |
1199 | |
999 | =over 4 |
1200 | =over 4 |
1000 | |
1201 | |
1001 | =item C<ev_init> (ev_TYPE *watcher, callback) |
1202 | =item C<ev_init> (ev_TYPE *watcher, callback) |
… | |
… | |
1017 | |
1218 | |
1018 | ev_io w; |
1219 | ev_io w; |
1019 | ev_init (&w, my_cb); |
1220 | ev_init (&w, my_cb); |
1020 | ev_io_set (&w, STDIN_FILENO, EV_READ); |
1221 | ev_io_set (&w, STDIN_FILENO, EV_READ); |
1021 | |
1222 | |
1022 | =item C<ev_TYPE_set> (ev_TYPE *, [args]) |
1223 | =item C<ev_TYPE_set> (ev_TYPE *watcher, [args]) |
1023 | |
1224 | |
1024 | This macro initialises the type-specific parts of a watcher. You need to |
1225 | This macro initialises the type-specific parts of a watcher. You need to |
1025 | call C<ev_init> at least once before you call this macro, but you can |
1226 | call C<ev_init> at least once before you call this macro, but you can |
1026 | call C<ev_TYPE_set> any number of times. You must not, however, call this |
1227 | call C<ev_TYPE_set> any number of times. You must not, however, call this |
1027 | macro on a watcher that is active (it can be pending, however, which is a |
1228 | macro on a watcher that is active (it can be pending, however, which is a |
… | |
… | |
1040 | |
1241 | |
1041 | Example: Initialise and set an C<ev_io> watcher in one step. |
1242 | Example: Initialise and set an C<ev_io> watcher in one step. |
1042 | |
1243 | |
1043 | ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1244 | ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1044 | |
1245 | |
1045 | =item C<ev_TYPE_start> (loop *, ev_TYPE *watcher) |
1246 | =item C<ev_TYPE_start> (loop, ev_TYPE *watcher) |
1046 | |
1247 | |
1047 | Starts (activates) the given watcher. Only active watchers will receive |
1248 | Starts (activates) the given watcher. Only active watchers will receive |
1048 | events. If the watcher is already active nothing will happen. |
1249 | events. If the watcher is already active nothing will happen. |
1049 | |
1250 | |
1050 | Example: Start the C<ev_io> watcher that is being abused as example in this |
1251 | Example: Start the C<ev_io> watcher that is being abused as example in this |
1051 | whole section. |
1252 | whole section. |
1052 | |
1253 | |
1053 | ev_io_start (EV_DEFAULT_UC, &w); |
1254 | ev_io_start (EV_DEFAULT_UC, &w); |
1054 | |
1255 | |
1055 | =item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher) |
1256 | =item C<ev_TYPE_stop> (loop, ev_TYPE *watcher) |
1056 | |
1257 | |
1057 | Stops the given watcher if active, and clears the pending status (whether |
1258 | Stops the given watcher if active, and clears the pending status (whether |
1058 | the watcher was active or not). |
1259 | the watcher was active or not). |
1059 | |
1260 | |
1060 | It is possible that stopped watchers are pending - for example, |
1261 | It is possible that stopped watchers are pending - for example, |
… | |
… | |
1085 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1286 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1086 | |
1287 | |
1087 | Change the callback. You can change the callback at virtually any time |
1288 | Change the callback. You can change the callback at virtually any time |
1088 | (modulo threads). |
1289 | (modulo threads). |
1089 | |
1290 | |
1090 | =item ev_set_priority (ev_TYPE *watcher, priority) |
1291 | =item ev_set_priority (ev_TYPE *watcher, int priority) |
1091 | |
1292 | |
1092 | =item int ev_priority (ev_TYPE *watcher) |
1293 | =item int ev_priority (ev_TYPE *watcher) |
1093 | |
1294 | |
1094 | Set and query the priority of the watcher. The priority is a small |
1295 | Set and query the priority of the watcher. The priority is a small |
1095 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
1296 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
… | |
… | |
1126 | returns its C<revents> bitset (as if its callback was invoked). If the |
1327 | returns its C<revents> bitset (as if its callback was invoked). If the |
1127 | watcher isn't pending it does nothing and returns C<0>. |
1328 | watcher isn't pending it does nothing and returns C<0>. |
1128 | |
1329 | |
1129 | Sometimes it can be useful to "poll" a watcher instead of waiting for its |
1330 | Sometimes it can be useful to "poll" a watcher instead of waiting for its |
1130 | callback to be invoked, which can be accomplished with this function. |
1331 | callback to be invoked, which can be accomplished with this function. |
|
|
1332 | |
|
|
1333 | =item ev_feed_event (loop, ev_TYPE *watcher, int revents) |
|
|
1334 | |
|
|
1335 | Feeds the given event set into the event loop, as if the specified event |
|
|
1336 | had happened for the specified watcher (which must be a pointer to an |
|
|
1337 | initialised but not necessarily started event watcher). Obviously you must |
|
|
1338 | not free the watcher as long as it has pending events. |
|
|
1339 | |
|
|
1340 | Stopping the watcher, letting libev invoke it, or calling |
|
|
1341 | C<ev_clear_pending> will clear the pending event, even if the watcher was |
|
|
1342 | not started in the first place. |
|
|
1343 | |
|
|
1344 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
|
|
1345 | functions that do not need a watcher. |
1131 | |
1346 | |
1132 | =back |
1347 | =back |
1133 | |
1348 | |
1134 | |
1349 | |
1135 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
1350 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
… | |
… | |
1184 | #include <stddef.h> |
1399 | #include <stddef.h> |
1185 | |
1400 | |
1186 | static void |
1401 | static void |
1187 | t1_cb (EV_P_ ev_timer *w, int revents) |
1402 | t1_cb (EV_P_ ev_timer *w, int revents) |
1188 | { |
1403 | { |
1189 | struct my_biggy big = (struct my_biggy * |
1404 | struct my_biggy big = (struct my_biggy *) |
1190 | (((char *)w) - offsetof (struct my_biggy, t1)); |
1405 | (((char *)w) - offsetof (struct my_biggy, t1)); |
1191 | } |
1406 | } |
1192 | |
1407 | |
1193 | static void |
1408 | static void |
1194 | t2_cb (EV_P_ ev_timer *w, int revents) |
1409 | t2_cb (EV_P_ ev_timer *w, int revents) |
1195 | { |
1410 | { |
1196 | struct my_biggy big = (struct my_biggy * |
1411 | struct my_biggy big = (struct my_biggy *) |
1197 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1412 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1198 | } |
1413 | } |
1199 | |
1414 | |
1200 | =head2 WATCHER PRIORITY MODELS |
1415 | =head2 WATCHER PRIORITY MODELS |
1201 | |
1416 | |
… | |
… | |
1246 | |
1461 | |
1247 | For example, to emulate how many other event libraries handle priorities, |
1462 | For example, to emulate how many other event libraries handle priorities, |
1248 | you can associate an C<ev_idle> watcher to each such watcher, and in |
1463 | you can associate an C<ev_idle> watcher to each such watcher, and in |
1249 | the normal watcher callback, you just start the idle watcher. The real |
1464 | the normal watcher callback, you just start the idle watcher. The real |
1250 | processing is done in the idle watcher callback. This causes libev to |
1465 | processing is done in the idle watcher callback. This causes libev to |
1251 | continously poll and process kernel event data for the watcher, but when |
1466 | continuously poll and process kernel event data for the watcher, but when |
1252 | the lock-out case is known to be rare (which in turn is rare :), this is |
1467 | the lock-out case is known to be rare (which in turn is rare :), this is |
1253 | workable. |
1468 | workable. |
1254 | |
1469 | |
1255 | Usually, however, the lock-out model implemented that way will perform |
1470 | Usually, however, the lock-out model implemented that way will perform |
1256 | miserably under the type of load it was designed to handle. In that case, |
1471 | miserably under the type of load it was designed to handle. In that case, |
… | |
… | |
1270 | { |
1485 | { |
1271 | // stop the I/O watcher, we received the event, but |
1486 | // stop the I/O watcher, we received the event, but |
1272 | // are not yet ready to handle it. |
1487 | // are not yet ready to handle it. |
1273 | ev_io_stop (EV_A_ w); |
1488 | ev_io_stop (EV_A_ w); |
1274 | |
1489 | |
1275 | // start the idle watcher to ahndle the actual event. |
1490 | // start the idle watcher to handle the actual event. |
1276 | // it will not be executed as long as other watchers |
1491 | // it will not be executed as long as other watchers |
1277 | // with the default priority are receiving events. |
1492 | // with the default priority are receiving events. |
1278 | ev_idle_start (EV_A_ &idle); |
1493 | ev_idle_start (EV_A_ &idle); |
1279 | } |
1494 | } |
1280 | |
1495 | |
1281 | static void |
1496 | static void |
1282 | idle-cb (EV_P_ ev_idle *w, int revents) |
1497 | idle_cb (EV_P_ ev_idle *w, int revents) |
1283 | { |
1498 | { |
1284 | // actual processing |
1499 | // actual processing |
1285 | read (STDIN_FILENO, ...); |
1500 | read (STDIN_FILENO, ...); |
1286 | |
1501 | |
1287 | // have to start the I/O watcher again, as |
1502 | // have to start the I/O watcher again, as |
… | |
… | |
1334 | |
1549 | |
1335 | If you cannot use non-blocking mode, then force the use of a |
1550 | If you cannot use non-blocking mode, then force the use of a |
1336 | known-to-be-good backend (at the time of this writing, this includes only |
1551 | known-to-be-good backend (at the time of this writing, this includes only |
1337 | C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file |
1552 | C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file |
1338 | descriptors for which non-blocking operation makes no sense (such as |
1553 | descriptors for which non-blocking operation makes no sense (such as |
1339 | files) - libev doesn't guarentee any specific behaviour in that case. |
1554 | files) - libev doesn't guarantee any specific behaviour in that case. |
1340 | |
1555 | |
1341 | Another thing you have to watch out for is that it is quite easy to |
1556 | Another thing you have to watch out for is that it is quite easy to |
1342 | receive "spurious" readiness notifications, that is your callback might |
1557 | receive "spurious" readiness notifications, that is your callback might |
1343 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1558 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1344 | because there is no data. Not only are some backends known to create a |
1559 | because there is no data. Not only are some backends known to create a |
… | |
… | |
1409 | |
1624 | |
1410 | So when you encounter spurious, unexplained daemon exits, make sure you |
1625 | So when you encounter spurious, unexplained daemon exits, make sure you |
1411 | ignore SIGPIPE (and maybe make sure you log the exit status of your daemon |
1626 | ignore SIGPIPE (and maybe make sure you log the exit status of your daemon |
1412 | somewhere, as that would have given you a big clue). |
1627 | somewhere, as that would have given you a big clue). |
1413 | |
1628 | |
|
|
1629 | =head3 The special problem of accept()ing when you can't |
|
|
1630 | |
|
|
1631 | Many implementations of the POSIX C<accept> function (for example, |
|
|
1632 | found in post-2004 Linux) have the peculiar behaviour of not removing a |
|
|
1633 | connection from the pending queue in all error cases. |
|
|
1634 | |
|
|
1635 | For example, larger servers often run out of file descriptors (because |
|
|
1636 | of resource limits), causing C<accept> to fail with C<ENFILE> but not |
|
|
1637 | rejecting the connection, leading to libev signalling readiness on |
|
|
1638 | the next iteration again (the connection still exists after all), and |
|
|
1639 | typically causing the program to loop at 100% CPU usage. |
|
|
1640 | |
|
|
1641 | Unfortunately, the set of errors that cause this issue differs between |
|
|
1642 | operating systems, there is usually little the app can do to remedy the |
|
|
1643 | situation, and no known thread-safe method of removing the connection to |
|
|
1644 | cope with overload is known (to me). |
|
|
1645 | |
|
|
1646 | One of the easiest ways to handle this situation is to just ignore it |
|
|
1647 | - when the program encounters an overload, it will just loop until the |
|
|
1648 | situation is over. While this is a form of busy waiting, no OS offers an |
|
|
1649 | event-based way to handle this situation, so it's the best one can do. |
|
|
1650 | |
|
|
1651 | A better way to handle the situation is to log any errors other than |
|
|
1652 | C<EAGAIN> and C<EWOULDBLOCK>, making sure not to flood the log with such |
|
|
1653 | messages, and continue as usual, which at least gives the user an idea of |
|
|
1654 | what could be wrong ("raise the ulimit!"). For extra points one could stop |
|
|
1655 | the C<ev_io> watcher on the listening fd "for a while", which reduces CPU |
|
|
1656 | usage. |
|
|
1657 | |
|
|
1658 | If your program is single-threaded, then you could also keep a dummy file |
|
|
1659 | descriptor for overload situations (e.g. by opening F</dev/null>), and |
|
|
1660 | when you run into C<ENFILE> or C<EMFILE>, close it, run C<accept>, |
|
|
1661 | close that fd, and create a new dummy fd. This will gracefully refuse |
|
|
1662 | clients under typical overload conditions. |
|
|
1663 | |
|
|
1664 | The last way to handle it is to simply log the error and C<exit>, as |
|
|
1665 | is often done with C<malloc> failures, but this results in an easy |
|
|
1666 | opportunity for a DoS attack. |
1414 | |
1667 | |
1415 | =head3 Watcher-Specific Functions |
1668 | =head3 Watcher-Specific Functions |
1416 | |
1669 | |
1417 | =over 4 |
1670 | =over 4 |
1418 | |
1671 | |
… | |
… | |
1450 | ... |
1703 | ... |
1451 | struct ev_loop *loop = ev_default_init (0); |
1704 | struct ev_loop *loop = ev_default_init (0); |
1452 | ev_io stdin_readable; |
1705 | ev_io stdin_readable; |
1453 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1706 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1454 | ev_io_start (loop, &stdin_readable); |
1707 | ev_io_start (loop, &stdin_readable); |
1455 | ev_loop (loop, 0); |
1708 | ev_run (loop, 0); |
1456 | |
1709 | |
1457 | |
1710 | |
1458 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1711 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1459 | |
1712 | |
1460 | Timer watchers are simple relative timers that generate an event after a |
1713 | Timer watchers are simple relative timers that generate an event after a |
… | |
… | |
1465 | year, it will still time out after (roughly) one hour. "Roughly" because |
1718 | year, it will still time out after (roughly) one hour. "Roughly" because |
1466 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1719 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1467 | monotonic clock option helps a lot here). |
1720 | monotonic clock option helps a lot here). |
1468 | |
1721 | |
1469 | The callback is guaranteed to be invoked only I<after> its timeout has |
1722 | The callback is guaranteed to be invoked only I<after> its timeout has |
1470 | passed. If multiple timers become ready during the same loop iteration |
1723 | passed (not I<at>, so on systems with very low-resolution clocks this |
1471 | then the ones with earlier time-out values are invoked before ones with |
1724 | might introduce a small delay). If multiple timers become ready during the |
1472 | later time-out values (but this is no longer true when a callback calls |
1725 | same loop iteration then the ones with earlier time-out values are invoked |
1473 | C<ev_loop> recursively). |
1726 | before ones of the same priority with later time-out values (but this is |
|
|
1727 | no longer true when a callback calls C<ev_run> recursively). |
1474 | |
1728 | |
1475 | =head3 Be smart about timeouts |
1729 | =head3 Be smart about timeouts |
1476 | |
1730 | |
1477 | Many real-world problems involve some kind of timeout, usually for error |
1731 | Many real-world problems involve some kind of timeout, usually for error |
1478 | recovery. A typical example is an HTTP request - if the other side hangs, |
1732 | recovery. A typical example is an HTTP request - if the other side hangs, |
… | |
… | |
1522 | C<after> argument to C<ev_timer_set>, and only ever use the C<repeat> |
1776 | C<after> argument to C<ev_timer_set>, and only ever use the C<repeat> |
1523 | member and C<ev_timer_again>. |
1777 | member and C<ev_timer_again>. |
1524 | |
1778 | |
1525 | At start: |
1779 | At start: |
1526 | |
1780 | |
1527 | ev_timer_init (timer, callback); |
1781 | ev_init (timer, callback); |
1528 | timer->repeat = 60.; |
1782 | timer->repeat = 60.; |
1529 | ev_timer_again (loop, timer); |
1783 | ev_timer_again (loop, timer); |
1530 | |
1784 | |
1531 | Each time there is some activity: |
1785 | Each time there is some activity: |
1532 | |
1786 | |
… | |
… | |
1564 | ev_tstamp timeout = last_activity + 60.; |
1818 | ev_tstamp timeout = last_activity + 60.; |
1565 | |
1819 | |
1566 | // if last_activity + 60. is older than now, we did time out |
1820 | // if last_activity + 60. is older than now, we did time out |
1567 | if (timeout < now) |
1821 | if (timeout < now) |
1568 | { |
1822 | { |
1569 | // timeout occured, take action |
1823 | // timeout occurred, take action |
1570 | } |
1824 | } |
1571 | else |
1825 | else |
1572 | { |
1826 | { |
1573 | // callback was invoked, but there was some activity, re-arm |
1827 | // callback was invoked, but there was some activity, re-arm |
1574 | // the watcher to fire in last_activity + 60, which is |
1828 | // the watcher to fire in last_activity + 60, which is |
… | |
… | |
1594 | |
1848 | |
1595 | To start the timer, simply initialise the watcher and set C<last_activity> |
1849 | To start the timer, simply initialise the watcher and set C<last_activity> |
1596 | to the current time (meaning we just have some activity :), then call the |
1850 | to the current time (meaning we just have some activity :), then call the |
1597 | callback, which will "do the right thing" and start the timer: |
1851 | callback, which will "do the right thing" and start the timer: |
1598 | |
1852 | |
1599 | ev_timer_init (timer, callback); |
1853 | ev_init (timer, callback); |
1600 | last_activity = ev_now (loop); |
1854 | last_activity = ev_now (loop); |
1601 | callback (loop, timer, EV_TIMEOUT); |
1855 | callback (loop, timer, EV_TIMER); |
1602 | |
1856 | |
1603 | And when there is some activity, simply store the current time in |
1857 | And when there is some activity, simply store the current time in |
1604 | C<last_activity>, no libev calls at all: |
1858 | C<last_activity>, no libev calls at all: |
1605 | |
1859 | |
1606 | last_actiivty = ev_now (loop); |
1860 | last_activity = ev_now (loop); |
1607 | |
1861 | |
1608 | This technique is slightly more complex, but in most cases where the |
1862 | This technique is slightly more complex, but in most cases where the |
1609 | time-out is unlikely to be triggered, much more efficient. |
1863 | time-out is unlikely to be triggered, much more efficient. |
1610 | |
1864 | |
1611 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
1865 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
… | |
… | |
1649 | |
1903 | |
1650 | =head3 The special problem of time updates |
1904 | =head3 The special problem of time updates |
1651 | |
1905 | |
1652 | Establishing the current time is a costly operation (it usually takes at |
1906 | Establishing the current time is a costly operation (it usually takes at |
1653 | least two system calls): EV therefore updates its idea of the current |
1907 | least two system calls): EV therefore updates its idea of the current |
1654 | time only before and after C<ev_loop> collects new events, which causes a |
1908 | time only before and after C<ev_run> collects new events, which causes a |
1655 | growing difference between C<ev_now ()> and C<ev_time ()> when handling |
1909 | growing difference between C<ev_now ()> and C<ev_time ()> when handling |
1656 | lots of events in one iteration. |
1910 | lots of events in one iteration. |
1657 | |
1911 | |
1658 | The relative timeouts are calculated relative to the C<ev_now ()> |
1912 | The relative timeouts are calculated relative to the C<ev_now ()> |
1659 | time. This is usually the right thing as this timestamp refers to the time |
1913 | time. This is usually the right thing as this timestamp refers to the time |
… | |
… | |
1665 | |
1919 | |
1666 | If the event loop is suspended for a long time, you can also force an |
1920 | If the event loop is suspended for a long time, you can also force an |
1667 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
1921 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
1668 | ()>. |
1922 | ()>. |
1669 | |
1923 | |
|
|
1924 | =head3 The special problems of suspended animation |
|
|
1925 | |
|
|
1926 | When you leave the server world it is quite customary to hit machines that |
|
|
1927 | can suspend/hibernate - what happens to the clocks during such a suspend? |
|
|
1928 | |
|
|
1929 | Some quick tests made with a Linux 2.6.28 indicate that a suspend freezes |
|
|
1930 | all processes, while the clocks (C<times>, C<CLOCK_MONOTONIC>) continue |
|
|
1931 | to run until the system is suspended, but they will not advance while the |
|
|
1932 | system is suspended. That means, on resume, it will be as if the program |
|
|
1933 | was frozen for a few seconds, but the suspend time will not be counted |
|
|
1934 | towards C<ev_timer> when a monotonic clock source is used. The real time |
|
|
1935 | clock advanced as expected, but if it is used as sole clocksource, then a |
|
|
1936 | long suspend would be detected as a time jump by libev, and timers would |
|
|
1937 | be adjusted accordingly. |
|
|
1938 | |
|
|
1939 | I would not be surprised to see different behaviour in different between |
|
|
1940 | operating systems, OS versions or even different hardware. |
|
|
1941 | |
|
|
1942 | The other form of suspend (job control, or sending a SIGSTOP) will see a |
|
|
1943 | time jump in the monotonic clocks and the realtime clock. If the program |
|
|
1944 | is suspended for a very long time, and monotonic clock sources are in use, |
|
|
1945 | then you can expect C<ev_timer>s to expire as the full suspension time |
|
|
1946 | will be counted towards the timers. When no monotonic clock source is in |
|
|
1947 | use, then libev will again assume a timejump and adjust accordingly. |
|
|
1948 | |
|
|
1949 | It might be beneficial for this latter case to call C<ev_suspend> |
|
|
1950 | and C<ev_resume> in code that handles C<SIGTSTP>, to at least get |
|
|
1951 | deterministic behaviour in this case (you can do nothing against |
|
|
1952 | C<SIGSTOP>). |
|
|
1953 | |
1670 | =head3 Watcher-Specific Functions and Data Members |
1954 | =head3 Watcher-Specific Functions and Data Members |
1671 | |
1955 | |
1672 | =over 4 |
1956 | =over 4 |
1673 | |
1957 | |
1674 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
1958 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
… | |
… | |
1700 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1984 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1701 | |
1985 | |
1702 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
1986 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
1703 | usage example. |
1987 | usage example. |
1704 | |
1988 | |
|
|
1989 | =item ev_tstamp ev_timer_remaining (loop, ev_timer *) |
|
|
1990 | |
|
|
1991 | Returns the remaining time until a timer fires. If the timer is active, |
|
|
1992 | then this time is relative to the current event loop time, otherwise it's |
|
|
1993 | the timeout value currently configured. |
|
|
1994 | |
|
|
1995 | That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns |
|
|
1996 | C<5>. When the timer is started and one second passes, C<ev_timer_remaining> |
|
|
1997 | will return C<4>. When the timer expires and is restarted, it will return |
|
|
1998 | roughly C<7> (likely slightly less as callback invocation takes some time, |
|
|
1999 | too), and so on. |
|
|
2000 | |
1705 | =item ev_tstamp repeat [read-write] |
2001 | =item ev_tstamp repeat [read-write] |
1706 | |
2002 | |
1707 | The current C<repeat> value. Will be used each time the watcher times out |
2003 | The current C<repeat> value. Will be used each time the watcher times out |
1708 | or C<ev_timer_again> is called, and determines the next timeout (if any), |
2004 | or C<ev_timer_again> is called, and determines the next timeout (if any), |
1709 | which is also when any modifications are taken into account. |
2005 | which is also when any modifications are taken into account. |
… | |
… | |
1734 | } |
2030 | } |
1735 | |
2031 | |
1736 | ev_timer mytimer; |
2032 | ev_timer mytimer; |
1737 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
2033 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1738 | ev_timer_again (&mytimer); /* start timer */ |
2034 | ev_timer_again (&mytimer); /* start timer */ |
1739 | ev_loop (loop, 0); |
2035 | ev_run (loop, 0); |
1740 | |
2036 | |
1741 | // and in some piece of code that gets executed on any "activity": |
2037 | // and in some piece of code that gets executed on any "activity": |
1742 | // reset the timeout to start ticking again at 10 seconds |
2038 | // reset the timeout to start ticking again at 10 seconds |
1743 | ev_timer_again (&mytimer); |
2039 | ev_timer_again (&mytimer); |
1744 | |
2040 | |
… | |
… | |
1770 | |
2066 | |
1771 | As with timers, the callback is guaranteed to be invoked only when the |
2067 | As with timers, the callback is guaranteed to be invoked only when the |
1772 | point in time where it is supposed to trigger has passed. If multiple |
2068 | point in time where it is supposed to trigger has passed. If multiple |
1773 | timers become ready during the same loop iteration then the ones with |
2069 | timers become ready during the same loop iteration then the ones with |
1774 | earlier time-out values are invoked before ones with later time-out values |
2070 | earlier time-out values are invoked before ones with later time-out values |
1775 | (but this is no longer true when a callback calls C<ev_loop> recursively). |
2071 | (but this is no longer true when a callback calls C<ev_run> recursively). |
1776 | |
2072 | |
1777 | =head3 Watcher-Specific Functions and Data Members |
2073 | =head3 Watcher-Specific Functions and Data Members |
1778 | |
2074 | |
1779 | =over 4 |
2075 | =over 4 |
1780 | |
2076 | |
… | |
… | |
1908 | Example: Call a callback every hour, or, more precisely, whenever the |
2204 | Example: Call a callback every hour, or, more precisely, whenever the |
1909 | system time is divisible by 3600. The callback invocation times have |
2205 | system time is divisible by 3600. The callback invocation times have |
1910 | potentially a lot of jitter, but good long-term stability. |
2206 | potentially a lot of jitter, but good long-term stability. |
1911 | |
2207 | |
1912 | static void |
2208 | static void |
1913 | clock_cb (struct ev_loop *loop, ev_io *w, int revents) |
2209 | clock_cb (struct ev_loop *loop, ev_periodic *w, int revents) |
1914 | { |
2210 | { |
1915 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
2211 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
1916 | } |
2212 | } |
1917 | |
2213 | |
1918 | ev_periodic hourly_tick; |
2214 | ev_periodic hourly_tick; |
… | |
… | |
1944 | Signal watchers will trigger an event when the process receives a specific |
2240 | Signal watchers will trigger an event when the process receives a specific |
1945 | signal one or more times. Even though signals are very asynchronous, libev |
2241 | signal one or more times. Even though signals are very asynchronous, libev |
1946 | will try it's best to deliver signals synchronously, i.e. as part of the |
2242 | will try it's best to deliver signals synchronously, i.e. as part of the |
1947 | normal event processing, like any other event. |
2243 | normal event processing, like any other event. |
1948 | |
2244 | |
1949 | If you want signals asynchronously, just use C<sigaction> as you would |
2245 | If you want signals to be delivered truly asynchronously, just use |
1950 | do without libev and forget about sharing the signal. You can even use |
2246 | C<sigaction> as you would do without libev and forget about sharing |
1951 | C<ev_async> from a signal handler to synchronously wake up an event loop. |
2247 | the signal. You can even use C<ev_async> from a signal handler to |
|
|
2248 | synchronously wake up an event loop. |
1952 | |
2249 | |
1953 | You can configure as many watchers as you like per signal. Only when the |
2250 | You can configure as many watchers as you like for the same signal, but |
|
|
2251 | only within the same loop, i.e. you can watch for C<SIGINT> in your |
|
|
2252 | default loop and for C<SIGIO> in another loop, but you cannot watch for |
|
|
2253 | C<SIGINT> in both the default loop and another loop at the same time. At |
|
|
2254 | the moment, C<SIGCHLD> is permanently tied to the default loop. |
|
|
2255 | |
1954 | first watcher gets started will libev actually register a signal handler |
2256 | When the first watcher gets started will libev actually register something |
1955 | with the kernel (thus it coexists with your own signal handlers as long as |
2257 | with the kernel (thus it coexists with your own signal handlers as long as |
1956 | you don't register any with libev for the same signal). Similarly, when |
2258 | you don't register any with libev for the same signal). |
1957 | the last signal watcher for a signal is stopped, libev will reset the |
|
|
1958 | signal handler to SIG_DFL (regardless of what it was set to before). |
|
|
1959 | |
2259 | |
1960 | If possible and supported, libev will install its handlers with |
2260 | If possible and supported, libev will install its handlers with |
1961 | C<SA_RESTART> behaviour enabled, so system calls should not be unduly |
2261 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
1962 | interrupted. If you have a problem with system calls getting interrupted by |
2262 | not be unduly interrupted. If you have a problem with system calls getting |
1963 | signals you can block all signals in an C<ev_check> watcher and unblock |
2263 | interrupted by signals you can block all signals in an C<ev_check> watcher |
1964 | them in an C<ev_prepare> watcher. |
2264 | and unblock them in an C<ev_prepare> watcher. |
|
|
2265 | |
|
|
2266 | =head3 The special problem of inheritance over fork/execve/pthread_create |
|
|
2267 | |
|
|
2268 | Both the signal mask (C<sigprocmask>) and the signal disposition |
|
|
2269 | (C<sigaction>) are unspecified after starting a signal watcher (and after |
|
|
2270 | stopping it again), that is, libev might or might not block the signal, |
|
|
2271 | and might or might not set or restore the installed signal handler. |
|
|
2272 | |
|
|
2273 | While this does not matter for the signal disposition (libev never |
|
|
2274 | sets signals to C<SIG_IGN>, so handlers will be reset to C<SIG_DFL> on |
|
|
2275 | C<execve>), this matters for the signal mask: many programs do not expect |
|
|
2276 | certain signals to be blocked. |
|
|
2277 | |
|
|
2278 | This means that before calling C<exec> (from the child) you should reset |
|
|
2279 | the signal mask to whatever "default" you expect (all clear is a good |
|
|
2280 | choice usually). |
|
|
2281 | |
|
|
2282 | The simplest way to ensure that the signal mask is reset in the child is |
|
|
2283 | to install a fork handler with C<pthread_atfork> that resets it. That will |
|
|
2284 | catch fork calls done by libraries (such as the libc) as well. |
|
|
2285 | |
|
|
2286 | In current versions of libev, the signal will not be blocked indefinitely |
|
|
2287 | unless you use the C<signalfd> API (C<EV_SIGNALFD>). While this reduces |
|
|
2288 | the window of opportunity for problems, it will not go away, as libev |
|
|
2289 | I<has> to modify the signal mask, at least temporarily. |
|
|
2290 | |
|
|
2291 | So I can't stress this enough: I<If you do not reset your signal mask when |
|
|
2292 | you expect it to be empty, you have a race condition in your code>. This |
|
|
2293 | is not a libev-specific thing, this is true for most event libraries. |
1965 | |
2294 | |
1966 | =head3 Watcher-Specific Functions and Data Members |
2295 | =head3 Watcher-Specific Functions and Data Members |
1967 | |
2296 | |
1968 | =over 4 |
2297 | =over 4 |
1969 | |
2298 | |
… | |
… | |
1985 | Example: Try to exit cleanly on SIGINT. |
2314 | Example: Try to exit cleanly on SIGINT. |
1986 | |
2315 | |
1987 | static void |
2316 | static void |
1988 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2317 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
1989 | { |
2318 | { |
1990 | ev_unloop (loop, EVUNLOOP_ALL); |
2319 | ev_break (loop, EVBREAK_ALL); |
1991 | } |
2320 | } |
1992 | |
2321 | |
1993 | ev_signal signal_watcher; |
2322 | ev_signal signal_watcher; |
1994 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2323 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1995 | ev_signal_start (loop, &signal_watcher); |
2324 | ev_signal_start (loop, &signal_watcher); |
… | |
… | |
2001 | some child status changes (most typically when a child of yours dies or |
2330 | some child status changes (most typically when a child of yours dies or |
2002 | exits). It is permissible to install a child watcher I<after> the child |
2331 | exits). It is permissible to install a child watcher I<after> the child |
2003 | has been forked (which implies it might have already exited), as long |
2332 | has been forked (which implies it might have already exited), as long |
2004 | as the event loop isn't entered (or is continued from a watcher), i.e., |
2333 | as the event loop isn't entered (or is continued from a watcher), i.e., |
2005 | forking and then immediately registering a watcher for the child is fine, |
2334 | forking and then immediately registering a watcher for the child is fine, |
2006 | but forking and registering a watcher a few event loop iterations later is |
2335 | but forking and registering a watcher a few event loop iterations later or |
2007 | not. |
2336 | in the next callback invocation is not. |
2008 | |
2337 | |
2009 | Only the default event loop is capable of handling signals, and therefore |
2338 | Only the default event loop is capable of handling signals, and therefore |
2010 | you can only register child watchers in the default event loop. |
2339 | you can only register child watchers in the default event loop. |
2011 | |
2340 | |
|
|
2341 | Due to some design glitches inside libev, child watchers will always be |
|
|
2342 | handled at maximum priority (their priority is set to C<EV_MAXPRI> by |
|
|
2343 | libev) |
|
|
2344 | |
2012 | =head3 Process Interaction |
2345 | =head3 Process Interaction |
2013 | |
2346 | |
2014 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
2347 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
2015 | initialised. This is necessary to guarantee proper behaviour even if |
2348 | initialised. This is necessary to guarantee proper behaviour even if the |
2016 | the first child watcher is started after the child exits. The occurrence |
2349 | first child watcher is started after the child exits. The occurrence |
2017 | of C<SIGCHLD> is recorded asynchronously, but child reaping is done |
2350 | of C<SIGCHLD> is recorded asynchronously, but child reaping is done |
2018 | synchronously as part of the event loop processing. Libev always reaps all |
2351 | synchronously as part of the event loop processing. Libev always reaps all |
2019 | children, even ones not watched. |
2352 | children, even ones not watched. |
2020 | |
2353 | |
2021 | =head3 Overriding the Built-In Processing |
2354 | =head3 Overriding the Built-In Processing |
… | |
… | |
2031 | =head3 Stopping the Child Watcher |
2364 | =head3 Stopping the Child Watcher |
2032 | |
2365 | |
2033 | Currently, the child watcher never gets stopped, even when the |
2366 | Currently, the child watcher never gets stopped, even when the |
2034 | child terminates, so normally one needs to stop the watcher in the |
2367 | child terminates, so normally one needs to stop the watcher in the |
2035 | callback. Future versions of libev might stop the watcher automatically |
2368 | callback. Future versions of libev might stop the watcher automatically |
2036 | when a child exit is detected. |
2369 | when a child exit is detected (calling C<ev_child_stop> twice is not a |
|
|
2370 | problem). |
2037 | |
2371 | |
2038 | =head3 Watcher-Specific Functions and Data Members |
2372 | =head3 Watcher-Specific Functions and Data Members |
2039 | |
2373 | |
2040 | =over 4 |
2374 | =over 4 |
2041 | |
2375 | |
… | |
… | |
2367 | // no longer anything immediate to do. |
2701 | // no longer anything immediate to do. |
2368 | } |
2702 | } |
2369 | |
2703 | |
2370 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
2704 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
2371 | ev_idle_init (idle_watcher, idle_cb); |
2705 | ev_idle_init (idle_watcher, idle_cb); |
2372 | ev_idle_start (loop, idle_cb); |
2706 | ev_idle_start (loop, idle_watcher); |
2373 | |
2707 | |
2374 | |
2708 | |
2375 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
2709 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
2376 | |
2710 | |
2377 | Prepare and check watchers are usually (but not always) used in pairs: |
2711 | Prepare and check watchers are usually (but not always) used in pairs: |
2378 | prepare watchers get invoked before the process blocks and check watchers |
2712 | prepare watchers get invoked before the process blocks and check watchers |
2379 | afterwards. |
2713 | afterwards. |
2380 | |
2714 | |
2381 | You I<must not> call C<ev_loop> or similar functions that enter |
2715 | You I<must not> call C<ev_run> or similar functions that enter |
2382 | the current event loop from either C<ev_prepare> or C<ev_check> |
2716 | the current event loop from either C<ev_prepare> or C<ev_check> |
2383 | watchers. Other loops than the current one are fine, however. The |
2717 | watchers. Other loops than the current one are fine, however. The |
2384 | rationale behind this is that you do not need to check for recursion in |
2718 | rationale behind this is that you do not need to check for recursion in |
2385 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
2719 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
2386 | C<ev_check> so if you have one watcher of each kind they will always be |
2720 | C<ev_check> so if you have one watcher of each kind they will always be |
… | |
… | |
2470 | struct pollfd fds [nfd]; |
2804 | struct pollfd fds [nfd]; |
2471 | // actual code will need to loop here and realloc etc. |
2805 | // actual code will need to loop here and realloc etc. |
2472 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
2806 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
2473 | |
2807 | |
2474 | /* the callback is illegal, but won't be called as we stop during check */ |
2808 | /* the callback is illegal, but won't be called as we stop during check */ |
2475 | ev_timer_init (&tw, 0, timeout * 1e-3); |
2809 | ev_timer_init (&tw, 0, timeout * 1e-3, 0.); |
2476 | ev_timer_start (loop, &tw); |
2810 | ev_timer_start (loop, &tw); |
2477 | |
2811 | |
2478 | // create one ev_io per pollfd |
2812 | // create one ev_io per pollfd |
2479 | for (int i = 0; i < nfd; ++i) |
2813 | for (int i = 0; i < nfd; ++i) |
2480 | { |
2814 | { |
… | |
… | |
2554 | |
2888 | |
2555 | if (timeout >= 0) |
2889 | if (timeout >= 0) |
2556 | // create/start timer |
2890 | // create/start timer |
2557 | |
2891 | |
2558 | // poll |
2892 | // poll |
2559 | ev_loop (EV_A_ 0); |
2893 | ev_run (EV_A_ 0); |
2560 | |
2894 | |
2561 | // stop timer again |
2895 | // stop timer again |
2562 | if (timeout >= 0) |
2896 | if (timeout >= 0) |
2563 | ev_timer_stop (EV_A_ &to); |
2897 | ev_timer_stop (EV_A_ &to); |
2564 | |
2898 | |
… | |
… | |
2642 | if you do not want that, you need to temporarily stop the embed watcher). |
2976 | if you do not want that, you need to temporarily stop the embed watcher). |
2643 | |
2977 | |
2644 | =item ev_embed_sweep (loop, ev_embed *) |
2978 | =item ev_embed_sweep (loop, ev_embed *) |
2645 | |
2979 | |
2646 | Make a single, non-blocking sweep over the embedded loop. This works |
2980 | Make a single, non-blocking sweep over the embedded loop. This works |
2647 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
2981 | similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most |
2648 | appropriate way for embedded loops. |
2982 | appropriate way for embedded loops. |
2649 | |
2983 | |
2650 | =item struct ev_loop *other [read-only] |
2984 | =item struct ev_loop *other [read-only] |
2651 | |
2985 | |
2652 | The embedded event loop. |
2986 | The embedded event loop. |
… | |
… | |
2712 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
3046 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
2713 | handlers will be invoked, too, of course. |
3047 | handlers will be invoked, too, of course. |
2714 | |
3048 | |
2715 | =head3 The special problem of life after fork - how is it possible? |
3049 | =head3 The special problem of life after fork - how is it possible? |
2716 | |
3050 | |
2717 | Most uses of C<fork()> consist of forking, then some simple calls to ste |
3051 | Most uses of C<fork()> consist of forking, then some simple calls to set |
2718 | up/change the process environment, followed by a call to C<exec()>. This |
3052 | up/change the process environment, followed by a call to C<exec()>. This |
2719 | sequence should be handled by libev without any problems. |
3053 | sequence should be handled by libev without any problems. |
2720 | |
3054 | |
2721 | This changes when the application actually wants to do event handling |
3055 | This changes when the application actually wants to do event handling |
2722 | in the child, or both parent in child, in effect "continuing" after the |
3056 | in the child, or both parent in child, in effect "continuing" after the |
… | |
… | |
2756 | believe me. |
3090 | believe me. |
2757 | |
3091 | |
2758 | =back |
3092 | =back |
2759 | |
3093 | |
2760 | |
3094 | |
2761 | =head2 C<ev_async> - how to wake up another event loop |
3095 | =head2 C<ev_async> - how to wake up an event loop |
2762 | |
3096 | |
2763 | In general, you cannot use an C<ev_loop> from multiple threads or other |
3097 | In general, you cannot use an C<ev_run> from multiple threads or other |
2764 | asynchronous sources such as signal handlers (as opposed to multiple event |
3098 | asynchronous sources such as signal handlers (as opposed to multiple event |
2765 | loops - those are of course safe to use in different threads). |
3099 | loops - those are of course safe to use in different threads). |
2766 | |
3100 | |
2767 | Sometimes, however, you need to wake up another event loop you do not |
3101 | Sometimes, however, you need to wake up an event loop you do not control, |
2768 | control, for example because it belongs to another thread. This is what |
3102 | for example because it belongs to another thread. This is what C<ev_async> |
2769 | C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you |
3103 | watchers do: as long as the C<ev_async> watcher is active, you can signal |
2770 | can signal it by calling C<ev_async_send>, which is thread- and signal |
3104 | it by calling C<ev_async_send>, which is thread- and signal safe. |
2771 | safe. |
|
|
2772 | |
3105 | |
2773 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3106 | This functionality is very similar to C<ev_signal> watchers, as signals, |
2774 | too, are asynchronous in nature, and signals, too, will be compressed |
3107 | too, are asynchronous in nature, and signals, too, will be compressed |
2775 | (i.e. the number of callback invocations may be less than the number of |
3108 | (i.e. the number of callback invocations may be less than the number of |
2776 | C<ev_async_sent> calls). |
3109 | C<ev_async_sent> calls). |
… | |
… | |
2781 | =head3 Queueing |
3114 | =head3 Queueing |
2782 | |
3115 | |
2783 | C<ev_async> does not support queueing of data in any way. The reason |
3116 | C<ev_async> does not support queueing of data in any way. The reason |
2784 | is that the author does not know of a simple (or any) algorithm for a |
3117 | is that the author does not know of a simple (or any) algorithm for a |
2785 | multiple-writer-single-reader queue that works in all cases and doesn't |
3118 | multiple-writer-single-reader queue that works in all cases and doesn't |
2786 | need elaborate support such as pthreads. |
3119 | need elaborate support such as pthreads or unportable memory access |
|
|
3120 | semantics. |
2787 | |
3121 | |
2788 | That means that if you want to queue data, you have to provide your own |
3122 | That means that if you want to queue data, you have to provide your own |
2789 | queue. But at least I can tell you how to implement locking around your |
3123 | queue. But at least I can tell you how to implement locking around your |
2790 | queue: |
3124 | queue: |
2791 | |
3125 | |
… | |
… | |
2930 | |
3264 | |
2931 | If C<timeout> is less than 0, then no timeout watcher will be |
3265 | If C<timeout> is less than 0, then no timeout watcher will be |
2932 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
3266 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
2933 | repeat = 0) will be started. C<0> is a valid timeout. |
3267 | repeat = 0) will be started. C<0> is a valid timeout. |
2934 | |
3268 | |
2935 | The callback has the type C<void (*cb)(int revents, void *arg)> and gets |
3269 | The callback has the type C<void (*cb)(int revents, void *arg)> and is |
2936 | passed an C<revents> set like normal event callbacks (a combination of |
3270 | passed an C<revents> set like normal event callbacks (a combination of |
2937 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> |
3271 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMER>) and the C<arg> |
2938 | value passed to C<ev_once>. Note that it is possible to receive I<both> |
3272 | value passed to C<ev_once>. Note that it is possible to receive I<both> |
2939 | a timeout and an io event at the same time - you probably should give io |
3273 | a timeout and an io event at the same time - you probably should give io |
2940 | events precedence. |
3274 | events precedence. |
2941 | |
3275 | |
2942 | Example: wait up to ten seconds for data to appear on STDIN_FILENO. |
3276 | Example: wait up to ten seconds for data to appear on STDIN_FILENO. |
2943 | |
3277 | |
2944 | static void stdin_ready (int revents, void *arg) |
3278 | static void stdin_ready (int revents, void *arg) |
2945 | { |
3279 | { |
2946 | if (revents & EV_READ) |
3280 | if (revents & EV_READ) |
2947 | /* stdin might have data for us, joy! */; |
3281 | /* stdin might have data for us, joy! */; |
2948 | else if (revents & EV_TIMEOUT) |
3282 | else if (revents & EV_TIMER) |
2949 | /* doh, nothing entered */; |
3283 | /* doh, nothing entered */; |
2950 | } |
3284 | } |
2951 | |
3285 | |
2952 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3286 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
2953 | |
3287 | |
2954 | =item ev_feed_event (struct ev_loop *, watcher *, int revents) |
|
|
2955 | |
|
|
2956 | Feeds the given event set into the event loop, as if the specified event |
|
|
2957 | had happened for the specified watcher (which must be a pointer to an |
|
|
2958 | initialised but not necessarily started event watcher). |
|
|
2959 | |
|
|
2960 | =item ev_feed_fd_event (struct ev_loop *, int fd, int revents) |
3288 | =item ev_feed_fd_event (loop, int fd, int revents) |
2961 | |
3289 | |
2962 | Feed an event on the given fd, as if a file descriptor backend detected |
3290 | Feed an event on the given fd, as if a file descriptor backend detected |
2963 | the given events it. |
3291 | the given events it. |
2964 | |
3292 | |
2965 | =item ev_feed_signal_event (struct ev_loop *loop, int signum) |
3293 | =item ev_feed_signal_event (loop, int signum) |
2966 | |
3294 | |
2967 | Feed an event as if the given signal occurred (C<loop> must be the default |
3295 | Feed an event as if the given signal occurred (C<loop> must be the default |
2968 | loop!). |
3296 | loop!). |
2969 | |
3297 | |
2970 | =back |
3298 | =back |
… | |
… | |
3050 | |
3378 | |
3051 | =over 4 |
3379 | =over 4 |
3052 | |
3380 | |
3053 | =item ev::TYPE::TYPE () |
3381 | =item ev::TYPE::TYPE () |
3054 | |
3382 | |
3055 | =item ev::TYPE::TYPE (struct ev_loop *) |
3383 | =item ev::TYPE::TYPE (loop) |
3056 | |
3384 | |
3057 | =item ev::TYPE::~TYPE |
3385 | =item ev::TYPE::~TYPE |
3058 | |
3386 | |
3059 | The constructor (optionally) takes an event loop to associate the watcher |
3387 | The constructor (optionally) takes an event loop to associate the watcher |
3060 | with. If it is omitted, it will use C<EV_DEFAULT>. |
3388 | with. If it is omitted, it will use C<EV_DEFAULT>. |
… | |
… | |
3093 | myclass obj; |
3421 | myclass obj; |
3094 | ev::io iow; |
3422 | ev::io iow; |
3095 | iow.set <myclass, &myclass::io_cb> (&obj); |
3423 | iow.set <myclass, &myclass::io_cb> (&obj); |
3096 | |
3424 | |
3097 | =item w->set (object *) |
3425 | =item w->set (object *) |
3098 | |
|
|
3099 | This is an B<experimental> feature that might go away in a future version. |
|
|
3100 | |
3426 | |
3101 | This is a variation of a method callback - leaving out the method to call |
3427 | This is a variation of a method callback - leaving out the method to call |
3102 | will default the method to C<operator ()>, which makes it possible to use |
3428 | will default the method to C<operator ()>, which makes it possible to use |
3103 | functor objects without having to manually specify the C<operator ()> all |
3429 | functor objects without having to manually specify the C<operator ()> all |
3104 | the time. Incidentally, you can then also leave out the template argument |
3430 | the time. Incidentally, you can then also leave out the template argument |
… | |
… | |
3137 | Example: Use a plain function as callback. |
3463 | Example: Use a plain function as callback. |
3138 | |
3464 | |
3139 | static void io_cb (ev::io &w, int revents) { } |
3465 | static void io_cb (ev::io &w, int revents) { } |
3140 | iow.set <io_cb> (); |
3466 | iow.set <io_cb> (); |
3141 | |
3467 | |
3142 | =item w->set (struct ev_loop *) |
3468 | =item w->set (loop) |
3143 | |
3469 | |
3144 | Associates a different C<struct ev_loop> with this watcher. You can only |
3470 | Associates a different C<struct ev_loop> with this watcher. You can only |
3145 | do this when the watcher is inactive (and not pending either). |
3471 | do this when the watcher is inactive (and not pending either). |
3146 | |
3472 | |
3147 | =item w->set ([arguments]) |
3473 | =item w->set ([arguments]) |
3148 | |
3474 | |
3149 | Basically the same as C<ev_TYPE_set>, with the same arguments. Must be |
3475 | Basically the same as C<ev_TYPE_set>, with the same arguments. Either this |
3150 | called at least once. Unlike the C counterpart, an active watcher gets |
3476 | method or a suitable start method must be called at least once. Unlike the |
3151 | automatically stopped and restarted when reconfiguring it with this |
3477 | C counterpart, an active watcher gets automatically stopped and restarted |
3152 | method. |
3478 | when reconfiguring it with this method. |
3153 | |
3479 | |
3154 | =item w->start () |
3480 | =item w->start () |
3155 | |
3481 | |
3156 | Starts the watcher. Note that there is no C<loop> argument, as the |
3482 | Starts the watcher. Note that there is no C<loop> argument, as the |
3157 | constructor already stores the event loop. |
3483 | constructor already stores the event loop. |
3158 | |
3484 | |
|
|
3485 | =item w->start ([arguments]) |
|
|
3486 | |
|
|
3487 | Instead of calling C<set> and C<start> methods separately, it is often |
|
|
3488 | convenient to wrap them in one call. Uses the same type of arguments as |
|
|
3489 | the configure C<set> method of the watcher. |
|
|
3490 | |
3159 | =item w->stop () |
3491 | =item w->stop () |
3160 | |
3492 | |
3161 | Stops the watcher if it is active. Again, no C<loop> argument. |
3493 | Stops the watcher if it is active. Again, no C<loop> argument. |
3162 | |
3494 | |
3163 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
3495 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
… | |
… | |
3175 | |
3507 | |
3176 | =back |
3508 | =back |
3177 | |
3509 | |
3178 | =back |
3510 | =back |
3179 | |
3511 | |
3180 | Example: Define a class with an IO and idle watcher, start one of them in |
3512 | Example: Define a class with two I/O and idle watchers, start the I/O |
3181 | the constructor. |
3513 | watchers in the constructor. |
3182 | |
3514 | |
3183 | class myclass |
3515 | class myclass |
3184 | { |
3516 | { |
3185 | ev::io io ; void io_cb (ev::io &w, int revents); |
3517 | ev::io io ; void io_cb (ev::io &w, int revents); |
|
|
3518 | ev::io2 io2 ; void io2_cb (ev::io &w, int revents); |
3186 | ev::idle idle; void idle_cb (ev::idle &w, int revents); |
3519 | ev::idle idle; void idle_cb (ev::idle &w, int revents); |
3187 | |
3520 | |
3188 | myclass (int fd) |
3521 | myclass (int fd) |
3189 | { |
3522 | { |
3190 | io .set <myclass, &myclass::io_cb > (this); |
3523 | io .set <myclass, &myclass::io_cb > (this); |
|
|
3524 | io2 .set <myclass, &myclass::io2_cb > (this); |
3191 | idle.set <myclass, &myclass::idle_cb> (this); |
3525 | idle.set <myclass, &myclass::idle_cb> (this); |
3192 | |
3526 | |
3193 | io.start (fd, ev::READ); |
3527 | io.set (fd, ev::WRITE); // configure the watcher |
|
|
3528 | io.start (); // start it whenever convenient |
|
|
3529 | |
|
|
3530 | io2.start (fd, ev::READ); // set + start in one call |
3194 | } |
3531 | } |
3195 | }; |
3532 | }; |
3196 | |
3533 | |
3197 | |
3534 | |
3198 | =head1 OTHER LANGUAGE BINDINGS |
3535 | =head1 OTHER LANGUAGE BINDINGS |
… | |
… | |
3244 | =item Ocaml |
3581 | =item Ocaml |
3245 | |
3582 | |
3246 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3583 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3247 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
3584 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
3248 | |
3585 | |
|
|
3586 | =item Lua |
|
|
3587 | |
|
|
3588 | Brian Maher has written a partial interface to libev for lua (at the |
|
|
3589 | time of this writing, only C<ev_io> and C<ev_timer>), to be found at |
|
|
3590 | L<http://github.com/brimworks/lua-ev>. |
|
|
3591 | |
3249 | =back |
3592 | =back |
3250 | |
3593 | |
3251 | |
3594 | |
3252 | =head1 MACRO MAGIC |
3595 | =head1 MACRO MAGIC |
3253 | |
3596 | |
… | |
… | |
3266 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
3609 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
3267 | C<EV_A_> is used when other arguments are following. Example: |
3610 | C<EV_A_> is used when other arguments are following. Example: |
3268 | |
3611 | |
3269 | ev_unref (EV_A); |
3612 | ev_unref (EV_A); |
3270 | ev_timer_add (EV_A_ watcher); |
3613 | ev_timer_add (EV_A_ watcher); |
3271 | ev_loop (EV_A_ 0); |
3614 | ev_run (EV_A_ 0); |
3272 | |
3615 | |
3273 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
3616 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
3274 | which is often provided by the following macro. |
3617 | which is often provided by the following macro. |
3275 | |
3618 | |
3276 | =item C<EV_P>, C<EV_P_> |
3619 | =item C<EV_P>, C<EV_P_> |
… | |
… | |
3316 | } |
3659 | } |
3317 | |
3660 | |
3318 | ev_check check; |
3661 | ev_check check; |
3319 | ev_check_init (&check, check_cb); |
3662 | ev_check_init (&check, check_cb); |
3320 | ev_check_start (EV_DEFAULT_ &check); |
3663 | ev_check_start (EV_DEFAULT_ &check); |
3321 | ev_loop (EV_DEFAULT_ 0); |
3664 | ev_run (EV_DEFAULT_ 0); |
3322 | |
3665 | |
3323 | =head1 EMBEDDING |
3666 | =head1 EMBEDDING |
3324 | |
3667 | |
3325 | Libev can (and often is) directly embedded into host |
3668 | Libev can (and often is) directly embedded into host |
3326 | applications. Examples of applications that embed it include the Deliantra |
3669 | applications. Examples of applications that embed it include the Deliantra |
… | |
… | |
3406 | libev.m4 |
3749 | libev.m4 |
3407 | |
3750 | |
3408 | =head2 PREPROCESSOR SYMBOLS/MACROS |
3751 | =head2 PREPROCESSOR SYMBOLS/MACROS |
3409 | |
3752 | |
3410 | Libev can be configured via a variety of preprocessor symbols you have to |
3753 | Libev can be configured via a variety of preprocessor symbols you have to |
3411 | define before including any of its files. The default in the absence of |
3754 | define before including (or compiling) any of its files. The default in |
3412 | autoconf is documented for every option. |
3755 | the absence of autoconf is documented for every option. |
|
|
3756 | |
|
|
3757 | Symbols marked with "(h)" do not change the ABI, and can have different |
|
|
3758 | values when compiling libev vs. including F<ev.h>, so it is permissible |
|
|
3759 | to redefine them before including F<ev.h> without breaking compatibility |
|
|
3760 | to a compiled library. All other symbols change the ABI, which means all |
|
|
3761 | users of libev and the libev code itself must be compiled with compatible |
|
|
3762 | settings. |
3413 | |
3763 | |
3414 | =over 4 |
3764 | =over 4 |
3415 | |
3765 | |
|
|
3766 | =item EV_COMPAT3 (h) |
|
|
3767 | |
|
|
3768 | Backwards compatibility is a major concern for libev. This is why this |
|
|
3769 | release of libev comes with wrappers for the functions and symbols that |
|
|
3770 | have been renamed between libev version 3 and 4. |
|
|
3771 | |
|
|
3772 | You can disable these wrappers (to test compatibility with future |
|
|
3773 | versions) by defining C<EV_COMPAT3> to C<0> when compiling your |
|
|
3774 | sources. This has the additional advantage that you can drop the C<struct> |
|
|
3775 | from C<struct ev_loop> declarations, as libev will provide an C<ev_loop> |
|
|
3776 | typedef in that case. |
|
|
3777 | |
|
|
3778 | In some future version, the default for C<EV_COMPAT3> will become C<0>, |
|
|
3779 | and in some even more future version the compatibility code will be |
|
|
3780 | removed completely. |
|
|
3781 | |
3416 | =item EV_STANDALONE |
3782 | =item EV_STANDALONE (h) |
3417 | |
3783 | |
3418 | Must always be C<1> if you do not use autoconf configuration, which |
3784 | Must always be C<1> if you do not use autoconf configuration, which |
3419 | keeps libev from including F<config.h>, and it also defines dummy |
3785 | keeps libev from including F<config.h>, and it also defines dummy |
3420 | implementations for some libevent functions (such as logging, which is not |
3786 | implementations for some libevent functions (such as logging, which is not |
3421 | supported). It will also not define any of the structs usually found in |
3787 | supported). It will also not define any of the structs usually found in |
3422 | F<event.h> that are not directly supported by the libev core alone. |
3788 | F<event.h> that are not directly supported by the libev core alone. |
3423 | |
3789 | |
3424 | In stanbdalone mode, libev will still try to automatically deduce the |
3790 | In standalone mode, libev will still try to automatically deduce the |
3425 | configuration, but has to be more conservative. |
3791 | configuration, but has to be more conservative. |
3426 | |
3792 | |
3427 | =item EV_USE_MONOTONIC |
3793 | =item EV_USE_MONOTONIC |
3428 | |
3794 | |
3429 | If defined to be C<1>, libev will try to detect the availability of the |
3795 | If defined to be C<1>, libev will try to detect the availability of the |
… | |
… | |
3494 | be used is the winsock select). This means that it will call |
3860 | be used is the winsock select). This means that it will call |
3495 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
3861 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
3496 | it is assumed that all these functions actually work on fds, even |
3862 | it is assumed that all these functions actually work on fds, even |
3497 | on win32. Should not be defined on non-win32 platforms. |
3863 | on win32. Should not be defined on non-win32 platforms. |
3498 | |
3864 | |
3499 | =item EV_FD_TO_WIN32_HANDLE |
3865 | =item EV_FD_TO_WIN32_HANDLE(fd) |
3500 | |
3866 | |
3501 | If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map |
3867 | If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map |
3502 | file descriptors to socket handles. When not defining this symbol (the |
3868 | file descriptors to socket handles. When not defining this symbol (the |
3503 | default), then libev will call C<_get_osfhandle>, which is usually |
3869 | default), then libev will call C<_get_osfhandle>, which is usually |
3504 | correct. In some cases, programs use their own file descriptor management, |
3870 | correct. In some cases, programs use their own file descriptor management, |
3505 | in which case they can provide this function to map fds to socket handles. |
3871 | in which case they can provide this function to map fds to socket handles. |
|
|
3872 | |
|
|
3873 | =item EV_WIN32_HANDLE_TO_FD(handle) |
|
|
3874 | |
|
|
3875 | If C<EV_SELECT_IS_WINSOCKET> then libev maps handles to file descriptors |
|
|
3876 | using the standard C<_open_osfhandle> function. For programs implementing |
|
|
3877 | their own fd to handle mapping, overwriting this function makes it easier |
|
|
3878 | to do so. This can be done by defining this macro to an appropriate value. |
|
|
3879 | |
|
|
3880 | =item EV_WIN32_CLOSE_FD(fd) |
|
|
3881 | |
|
|
3882 | If programs implement their own fd to handle mapping on win32, then this |
|
|
3883 | macro can be used to override the C<close> function, useful to unregister |
|
|
3884 | file descriptors again. Note that the replacement function has to close |
|
|
3885 | the underlying OS handle. |
3506 | |
3886 | |
3507 | =item EV_USE_POLL |
3887 | =item EV_USE_POLL |
3508 | |
3888 | |
3509 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
3889 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
3510 | backend. Otherwise it will be enabled on non-win32 platforms. It |
3890 | backend. Otherwise it will be enabled on non-win32 platforms. It |
… | |
… | |
3557 | as well as for signal and thread safety in C<ev_async> watchers. |
3937 | as well as for signal and thread safety in C<ev_async> watchers. |
3558 | |
3938 | |
3559 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
3939 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
3560 | (from F<signal.h>), which is usually good enough on most platforms. |
3940 | (from F<signal.h>), which is usually good enough on most platforms. |
3561 | |
3941 | |
3562 | =item EV_H |
3942 | =item EV_H (h) |
3563 | |
3943 | |
3564 | The name of the F<ev.h> header file used to include it. The default if |
3944 | The name of the F<ev.h> header file used to include it. The default if |
3565 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
3945 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
3566 | used to virtually rename the F<ev.h> header file in case of conflicts. |
3946 | used to virtually rename the F<ev.h> header file in case of conflicts. |
3567 | |
3947 | |
3568 | =item EV_CONFIG_H |
3948 | =item EV_CONFIG_H (h) |
3569 | |
3949 | |
3570 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
3950 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
3571 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
3951 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
3572 | C<EV_H>, above. |
3952 | C<EV_H>, above. |
3573 | |
3953 | |
3574 | =item EV_EVENT_H |
3954 | =item EV_EVENT_H (h) |
3575 | |
3955 | |
3576 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
3956 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
3577 | of how the F<event.h> header can be found, the default is C<"event.h">. |
3957 | of how the F<event.h> header can be found, the default is C<"event.h">. |
3578 | |
3958 | |
3579 | =item EV_PROTOTYPES |
3959 | =item EV_PROTOTYPES (h) |
3580 | |
3960 | |
3581 | If defined to be C<0>, then F<ev.h> will not define any function |
3961 | If defined to be C<0>, then F<ev.h> will not define any function |
3582 | prototypes, but still define all the structs and other symbols. This is |
3962 | prototypes, but still define all the structs and other symbols. This is |
3583 | occasionally useful if you want to provide your own wrapper functions |
3963 | occasionally useful if you want to provide your own wrapper functions |
3584 | around libev functions. |
3964 | around libev functions. |
… | |
… | |
3606 | fine. |
3986 | fine. |
3607 | |
3987 | |
3608 | If your embedding application does not need any priorities, defining these |
3988 | If your embedding application does not need any priorities, defining these |
3609 | both to C<0> will save some memory and CPU. |
3989 | both to C<0> will save some memory and CPU. |
3610 | |
3990 | |
3611 | =item EV_PERIODIC_ENABLE |
3991 | =item EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE, |
|
|
3992 | EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, |
|
|
3993 | EV_ASYNC_ENABLE, EV_CHILD_ENABLE. |
3612 | |
3994 | |
3613 | If undefined or defined to be C<1>, then periodic timers are supported. If |
3995 | If undefined or defined to be C<1> (and the platform supports it), then |
3614 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
3996 | the respective watcher type is supported. If defined to be C<0>, then it |
3615 | code. |
3997 | is not. Disabling watcher types mainly saves code size. |
3616 | |
3998 | |
3617 | =item EV_IDLE_ENABLE |
3999 | =item EV_FEATURES |
3618 | |
|
|
3619 | If undefined or defined to be C<1>, then idle watchers are supported. If |
|
|
3620 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
3621 | code. |
|
|
3622 | |
|
|
3623 | =item EV_EMBED_ENABLE |
|
|
3624 | |
|
|
3625 | If undefined or defined to be C<1>, then embed watchers are supported. If |
|
|
3626 | defined to be C<0>, then they are not. Embed watchers rely on most other |
|
|
3627 | watcher types, which therefore must not be disabled. |
|
|
3628 | |
|
|
3629 | =item EV_STAT_ENABLE |
|
|
3630 | |
|
|
3631 | If undefined or defined to be C<1>, then stat watchers are supported. If |
|
|
3632 | defined to be C<0>, then they are not. |
|
|
3633 | |
|
|
3634 | =item EV_FORK_ENABLE |
|
|
3635 | |
|
|
3636 | If undefined or defined to be C<1>, then fork watchers are supported. If |
|
|
3637 | defined to be C<0>, then they are not. |
|
|
3638 | |
|
|
3639 | =item EV_ASYNC_ENABLE |
|
|
3640 | |
|
|
3641 | If undefined or defined to be C<1>, then async watchers are supported. If |
|
|
3642 | defined to be C<0>, then they are not. |
|
|
3643 | |
|
|
3644 | =item EV_MINIMAL |
|
|
3645 | |
4000 | |
3646 | If you need to shave off some kilobytes of code at the expense of some |
4001 | If you need to shave off some kilobytes of code at the expense of some |
3647 | speed, define this symbol to C<1>. Currently this is used to override some |
4002 | speed (but with the full API), you can define this symbol to request |
3648 | inlining decisions, saves roughly 30% code size on amd64. It also selects a |
4003 | certain subsets of functionality. The default is to enable all features |
3649 | much smaller 2-heap for timer management over the default 4-heap. |
4004 | that can be enabled on the platform. |
|
|
4005 | |
|
|
4006 | A typical way to use this symbol is to define it to C<0> (or to a bitset |
|
|
4007 | with some broad features you want) and then selectively re-enable |
|
|
4008 | additional parts you want, for example if you want everything minimal, |
|
|
4009 | but multiple event loop support, async and child watchers and the poll |
|
|
4010 | backend, use this: |
|
|
4011 | |
|
|
4012 | #define EV_FEATURES 0 |
|
|
4013 | #define EV_MULTIPLICITY 1 |
|
|
4014 | #define EV_USE_POLL 1 |
|
|
4015 | #define EV_CHILD_ENABLE 1 |
|
|
4016 | #define EV_ASYNC_ENABLE 1 |
|
|
4017 | |
|
|
4018 | The actual value is a bitset, it can be a combination of the following |
|
|
4019 | values: |
|
|
4020 | |
|
|
4021 | =over 4 |
|
|
4022 | |
|
|
4023 | =item C<1> - faster/larger code |
|
|
4024 | |
|
|
4025 | Use larger code to speed up some operations. |
|
|
4026 | |
|
|
4027 | Currently this is used to override some inlining decisions (enlarging the |
|
|
4028 | code size by roughly 30% on amd64). |
|
|
4029 | |
|
|
4030 | When optimising for size, use of compiler flags such as C<-Os> with |
|
|
4031 | gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of |
|
|
4032 | assertions. |
|
|
4033 | |
|
|
4034 | =item C<2> - faster/larger data structures |
|
|
4035 | |
|
|
4036 | Replaces the small 2-heap for timer management by a faster 4-heap, larger |
|
|
4037 | hash table sizes and so on. This will usually further increase code size |
|
|
4038 | and can additionally have an effect on the size of data structures at |
|
|
4039 | runtime. |
|
|
4040 | |
|
|
4041 | =item C<4> - full API configuration |
|
|
4042 | |
|
|
4043 | This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and |
|
|
4044 | enables multiplicity (C<EV_MULTIPLICITY>=1). |
|
|
4045 | |
|
|
4046 | =item C<8> - full API |
|
|
4047 | |
|
|
4048 | This enables a lot of the "lesser used" API functions. See C<ev.h> for |
|
|
4049 | details on which parts of the API are still available without this |
|
|
4050 | feature, and do not complain if this subset changes over time. |
|
|
4051 | |
|
|
4052 | =item C<16> - enable all optional watcher types |
|
|
4053 | |
|
|
4054 | Enables all optional watcher types. If you want to selectively enable |
|
|
4055 | only some watcher types other than I/O and timers (e.g. prepare, |
|
|
4056 | embed, async, child...) you can enable them manually by defining |
|
|
4057 | C<EV_watchertype_ENABLE> to C<1> instead. |
|
|
4058 | |
|
|
4059 | =item C<32> - enable all backends |
|
|
4060 | |
|
|
4061 | This enables all backends - without this feature, you need to enable at |
|
|
4062 | least one backend manually (C<EV_USE_SELECT> is a good choice). |
|
|
4063 | |
|
|
4064 | =item C<64> - enable OS-specific "helper" APIs |
|
|
4065 | |
|
|
4066 | Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by |
|
|
4067 | default. |
|
|
4068 | |
|
|
4069 | =back |
|
|
4070 | |
|
|
4071 | Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0> |
|
|
4072 | reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb |
|
|
4073 | code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O |
|
|
4074 | watchers, timers and monotonic clock support. |
|
|
4075 | |
|
|
4076 | With an intelligent-enough linker (gcc+binutils are intelligent enough |
|
|
4077 | when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by |
|
|
4078 | your program might be left out as well - a binary starting a timer and an |
|
|
4079 | I/O watcher then might come out at only 5Kb. |
|
|
4080 | |
|
|
4081 | =item EV_AVOID_STDIO |
|
|
4082 | |
|
|
4083 | If this is set to C<1> at compiletime, then libev will avoid using stdio |
|
|
4084 | functions (printf, scanf, perror etc.). This will increase the code size |
|
|
4085 | somewhat, but if your program doesn't otherwise depend on stdio and your |
|
|
4086 | libc allows it, this avoids linking in the stdio library which is quite |
|
|
4087 | big. |
|
|
4088 | |
|
|
4089 | Note that error messages might become less precise when this option is |
|
|
4090 | enabled. |
|
|
4091 | |
|
|
4092 | =item EV_NSIG |
|
|
4093 | |
|
|
4094 | The highest supported signal number, +1 (or, the number of |
|
|
4095 | signals): Normally, libev tries to deduce the maximum number of signals |
|
|
4096 | automatically, but sometimes this fails, in which case it can be |
|
|
4097 | specified. Also, using a lower number than detected (C<32> should be |
|
|
4098 | good for about any system in existence) can save some memory, as libev |
|
|
4099 | statically allocates some 12-24 bytes per signal number. |
3650 | |
4100 | |
3651 | =item EV_PID_HASHSIZE |
4101 | =item EV_PID_HASHSIZE |
3652 | |
4102 | |
3653 | C<ev_child> watchers use a small hash table to distribute workload by |
4103 | C<ev_child> watchers use a small hash table to distribute workload by |
3654 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
4104 | pid. The default size is C<16> (or C<1> with C<EV_FEATURES> disabled), |
3655 | than enough. If you need to manage thousands of children you might want to |
4105 | usually more than enough. If you need to manage thousands of children you |
3656 | increase this value (I<must> be a power of two). |
4106 | might want to increase this value (I<must> be a power of two). |
3657 | |
4107 | |
3658 | =item EV_INOTIFY_HASHSIZE |
4108 | =item EV_INOTIFY_HASHSIZE |
3659 | |
4109 | |
3660 | C<ev_stat> watchers use a small hash table to distribute workload by |
4110 | C<ev_stat> watchers use a small hash table to distribute workload by |
3661 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
4111 | inotify watch id. The default size is C<16> (or C<1> with C<EV_FEATURES> |
3662 | usually more than enough. If you need to manage thousands of C<ev_stat> |
4112 | disabled), usually more than enough. If you need to manage thousands of |
3663 | watchers you might want to increase this value (I<must> be a power of |
4113 | C<ev_stat> watchers you might want to increase this value (I<must> be a |
3664 | two). |
4114 | power of two). |
3665 | |
4115 | |
3666 | =item EV_USE_4HEAP |
4116 | =item EV_USE_4HEAP |
3667 | |
4117 | |
3668 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4118 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3669 | timer and periodics heaps, libev uses a 4-heap when this symbol is defined |
4119 | timer and periodics heaps, libev uses a 4-heap when this symbol is defined |
3670 | to C<1>. The 4-heap uses more complicated (longer) code but has noticeably |
4120 | to C<1>. The 4-heap uses more complicated (longer) code but has noticeably |
3671 | faster performance with many (thousands) of watchers. |
4121 | faster performance with many (thousands) of watchers. |
3672 | |
4122 | |
3673 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
4123 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3674 | (disabled). |
4124 | will be C<0>. |
3675 | |
4125 | |
3676 | =item EV_HEAP_CACHE_AT |
4126 | =item EV_HEAP_CACHE_AT |
3677 | |
4127 | |
3678 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4128 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3679 | timer and periodics heaps, libev can cache the timestamp (I<at>) within |
4129 | timer and periodics heaps, libev can cache the timestamp (I<at>) within |
3680 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
4130 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
3681 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
4131 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
3682 | but avoids random read accesses on heap changes. This improves performance |
4132 | but avoids random read accesses on heap changes. This improves performance |
3683 | noticeably with many (hundreds) of watchers. |
4133 | noticeably with many (hundreds) of watchers. |
3684 | |
4134 | |
3685 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
4135 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3686 | (disabled). |
4136 | will be C<0>. |
3687 | |
4137 | |
3688 | =item EV_VERIFY |
4138 | =item EV_VERIFY |
3689 | |
4139 | |
3690 | Controls how much internal verification (see C<ev_loop_verify ()>) will |
4140 | Controls how much internal verification (see C<ev_verify ()>) will |
3691 | be done: If set to C<0>, no internal verification code will be compiled |
4141 | be done: If set to C<0>, no internal verification code will be compiled |
3692 | in. If set to C<1>, then verification code will be compiled in, but not |
4142 | in. If set to C<1>, then verification code will be compiled in, but not |
3693 | called. If set to C<2>, then the internal verification code will be |
4143 | called. If set to C<2>, then the internal verification code will be |
3694 | called once per loop, which can slow down libev. If set to C<3>, then the |
4144 | called once per loop, which can slow down libev. If set to C<3>, then the |
3695 | verification code will be called very frequently, which will slow down |
4145 | verification code will be called very frequently, which will slow down |
3696 | libev considerably. |
4146 | libev considerably. |
3697 | |
4147 | |
3698 | The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be |
4148 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3699 | C<0>. |
4149 | will be C<0>. |
3700 | |
4150 | |
3701 | =item EV_COMMON |
4151 | =item EV_COMMON |
3702 | |
4152 | |
3703 | By default, all watchers have a C<void *data> member. By redefining |
4153 | By default, all watchers have a C<void *data> member. By redefining |
3704 | this macro to a something else you can include more and other types of |
4154 | this macro to something else you can include more and other types of |
3705 | members. You have to define it each time you include one of the files, |
4155 | members. You have to define it each time you include one of the files, |
3706 | though, and it must be identical each time. |
4156 | though, and it must be identical each time. |
3707 | |
4157 | |
3708 | For example, the perl EV module uses something like this: |
4158 | For example, the perl EV module uses something like this: |
3709 | |
4159 | |
… | |
… | |
3762 | file. |
4212 | file. |
3763 | |
4213 | |
3764 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
4214 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
3765 | that everybody includes and which overrides some configure choices: |
4215 | that everybody includes and which overrides some configure choices: |
3766 | |
4216 | |
3767 | #define EV_MINIMAL 1 |
4217 | #define EV_FEATURES 8 |
3768 | #define EV_USE_POLL 0 |
4218 | #define EV_USE_SELECT 1 |
3769 | #define EV_MULTIPLICITY 0 |
|
|
3770 | #define EV_PERIODIC_ENABLE 0 |
4219 | #define EV_PREPARE_ENABLE 1 |
|
|
4220 | #define EV_IDLE_ENABLE 1 |
3771 | #define EV_STAT_ENABLE 0 |
4221 | #define EV_SIGNAL_ENABLE 1 |
3772 | #define EV_FORK_ENABLE 0 |
4222 | #define EV_CHILD_ENABLE 1 |
|
|
4223 | #define EV_USE_STDEXCEPT 0 |
3773 | #define EV_CONFIG_H <config.h> |
4224 | #define EV_CONFIG_H <config.h> |
3774 | #define EV_MINPRI 0 |
|
|
3775 | #define EV_MAXPRI 0 |
|
|
3776 | |
4225 | |
3777 | #include "ev++.h" |
4226 | #include "ev++.h" |
3778 | |
4227 | |
3779 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
4228 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
3780 | |
4229 | |
… | |
… | |
3840 | default loop and triggering an C<ev_async> watcher from the default loop |
4289 | default loop and triggering an C<ev_async> watcher from the default loop |
3841 | watcher callback into the event loop interested in the signal. |
4290 | watcher callback into the event loop interested in the signal. |
3842 | |
4291 | |
3843 | =back |
4292 | =back |
3844 | |
4293 | |
|
|
4294 | =head4 THREAD LOCKING EXAMPLE |
|
|
4295 | |
|
|
4296 | Here is a fictitious example of how to run an event loop in a different |
|
|
4297 | thread than where callbacks are being invoked and watchers are |
|
|
4298 | created/added/removed. |
|
|
4299 | |
|
|
4300 | For a real-world example, see the C<EV::Loop::Async> perl module, |
|
|
4301 | which uses exactly this technique (which is suited for many high-level |
|
|
4302 | languages). |
|
|
4303 | |
|
|
4304 | The example uses a pthread mutex to protect the loop data, a condition |
|
|
4305 | variable to wait for callback invocations, an async watcher to notify the |
|
|
4306 | event loop thread and an unspecified mechanism to wake up the main thread. |
|
|
4307 | |
|
|
4308 | First, you need to associate some data with the event loop: |
|
|
4309 | |
|
|
4310 | typedef struct { |
|
|
4311 | mutex_t lock; /* global loop lock */ |
|
|
4312 | ev_async async_w; |
|
|
4313 | thread_t tid; |
|
|
4314 | cond_t invoke_cv; |
|
|
4315 | } userdata; |
|
|
4316 | |
|
|
4317 | void prepare_loop (EV_P) |
|
|
4318 | { |
|
|
4319 | // for simplicity, we use a static userdata struct. |
|
|
4320 | static userdata u; |
|
|
4321 | |
|
|
4322 | ev_async_init (&u->async_w, async_cb); |
|
|
4323 | ev_async_start (EV_A_ &u->async_w); |
|
|
4324 | |
|
|
4325 | pthread_mutex_init (&u->lock, 0); |
|
|
4326 | pthread_cond_init (&u->invoke_cv, 0); |
|
|
4327 | |
|
|
4328 | // now associate this with the loop |
|
|
4329 | ev_set_userdata (EV_A_ u); |
|
|
4330 | ev_set_invoke_pending_cb (EV_A_ l_invoke); |
|
|
4331 | ev_set_loop_release_cb (EV_A_ l_release, l_acquire); |
|
|
4332 | |
|
|
4333 | // then create the thread running ev_loop |
|
|
4334 | pthread_create (&u->tid, 0, l_run, EV_A); |
|
|
4335 | } |
|
|
4336 | |
|
|
4337 | The callback for the C<ev_async> watcher does nothing: the watcher is used |
|
|
4338 | solely to wake up the event loop so it takes notice of any new watchers |
|
|
4339 | that might have been added: |
|
|
4340 | |
|
|
4341 | static void |
|
|
4342 | async_cb (EV_P_ ev_async *w, int revents) |
|
|
4343 | { |
|
|
4344 | // just used for the side effects |
|
|
4345 | } |
|
|
4346 | |
|
|
4347 | The C<l_release> and C<l_acquire> callbacks simply unlock/lock the mutex |
|
|
4348 | protecting the loop data, respectively. |
|
|
4349 | |
|
|
4350 | static void |
|
|
4351 | l_release (EV_P) |
|
|
4352 | { |
|
|
4353 | userdata *u = ev_userdata (EV_A); |
|
|
4354 | pthread_mutex_unlock (&u->lock); |
|
|
4355 | } |
|
|
4356 | |
|
|
4357 | static void |
|
|
4358 | l_acquire (EV_P) |
|
|
4359 | { |
|
|
4360 | userdata *u = ev_userdata (EV_A); |
|
|
4361 | pthread_mutex_lock (&u->lock); |
|
|
4362 | } |
|
|
4363 | |
|
|
4364 | The event loop thread first acquires the mutex, and then jumps straight |
|
|
4365 | into C<ev_run>: |
|
|
4366 | |
|
|
4367 | void * |
|
|
4368 | l_run (void *thr_arg) |
|
|
4369 | { |
|
|
4370 | struct ev_loop *loop = (struct ev_loop *)thr_arg; |
|
|
4371 | |
|
|
4372 | l_acquire (EV_A); |
|
|
4373 | pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
|
|
4374 | ev_run (EV_A_ 0); |
|
|
4375 | l_release (EV_A); |
|
|
4376 | |
|
|
4377 | return 0; |
|
|
4378 | } |
|
|
4379 | |
|
|
4380 | Instead of invoking all pending watchers, the C<l_invoke> callback will |
|
|
4381 | signal the main thread via some unspecified mechanism (signals? pipe |
|
|
4382 | writes? C<Async::Interrupt>?) and then waits until all pending watchers |
|
|
4383 | have been called (in a while loop because a) spurious wakeups are possible |
|
|
4384 | and b) skipping inter-thread-communication when there are no pending |
|
|
4385 | watchers is very beneficial): |
|
|
4386 | |
|
|
4387 | static void |
|
|
4388 | l_invoke (EV_P) |
|
|
4389 | { |
|
|
4390 | userdata *u = ev_userdata (EV_A); |
|
|
4391 | |
|
|
4392 | while (ev_pending_count (EV_A)) |
|
|
4393 | { |
|
|
4394 | wake_up_other_thread_in_some_magic_or_not_so_magic_way (); |
|
|
4395 | pthread_cond_wait (&u->invoke_cv, &u->lock); |
|
|
4396 | } |
|
|
4397 | } |
|
|
4398 | |
|
|
4399 | Now, whenever the main thread gets told to invoke pending watchers, it |
|
|
4400 | will grab the lock, call C<ev_invoke_pending> and then signal the loop |
|
|
4401 | thread to continue: |
|
|
4402 | |
|
|
4403 | static void |
|
|
4404 | real_invoke_pending (EV_P) |
|
|
4405 | { |
|
|
4406 | userdata *u = ev_userdata (EV_A); |
|
|
4407 | |
|
|
4408 | pthread_mutex_lock (&u->lock); |
|
|
4409 | ev_invoke_pending (EV_A); |
|
|
4410 | pthread_cond_signal (&u->invoke_cv); |
|
|
4411 | pthread_mutex_unlock (&u->lock); |
|
|
4412 | } |
|
|
4413 | |
|
|
4414 | Whenever you want to start/stop a watcher or do other modifications to an |
|
|
4415 | event loop, you will now have to lock: |
|
|
4416 | |
|
|
4417 | ev_timer timeout_watcher; |
|
|
4418 | userdata *u = ev_userdata (EV_A); |
|
|
4419 | |
|
|
4420 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
|
|
4421 | |
|
|
4422 | pthread_mutex_lock (&u->lock); |
|
|
4423 | ev_timer_start (EV_A_ &timeout_watcher); |
|
|
4424 | ev_async_send (EV_A_ &u->async_w); |
|
|
4425 | pthread_mutex_unlock (&u->lock); |
|
|
4426 | |
|
|
4427 | Note that sending the C<ev_async> watcher is required because otherwise |
|
|
4428 | an event loop currently blocking in the kernel will have no knowledge |
|
|
4429 | about the newly added timer. By waking up the loop it will pick up any new |
|
|
4430 | watchers in the next event loop iteration. |
|
|
4431 | |
3845 | =head3 COROUTINES |
4432 | =head3 COROUTINES |
3846 | |
4433 | |
3847 | Libev is very accommodating to coroutines ("cooperative threads"): |
4434 | Libev is very accommodating to coroutines ("cooperative threads"): |
3848 | libev fully supports nesting calls to its functions from different |
4435 | libev fully supports nesting calls to its functions from different |
3849 | coroutines (e.g. you can call C<ev_loop> on the same loop from two |
4436 | coroutines (e.g. you can call C<ev_run> on the same loop from two |
3850 | different coroutines, and switch freely between both coroutines running the |
4437 | different coroutines, and switch freely between both coroutines running |
3851 | loop, as long as you don't confuse yourself). The only exception is that |
4438 | the loop, as long as you don't confuse yourself). The only exception is |
3852 | you must not do this from C<ev_periodic> reschedule callbacks. |
4439 | that you must not do this from C<ev_periodic> reschedule callbacks. |
3853 | |
4440 | |
3854 | Care has been taken to ensure that libev does not keep local state inside |
4441 | Care has been taken to ensure that libev does not keep local state inside |
3855 | C<ev_loop>, and other calls do not usually allow for coroutine switches as |
4442 | C<ev_run>, and other calls do not usually allow for coroutine switches as |
3856 | they do not call any callbacks. |
4443 | they do not call any callbacks. |
3857 | |
4444 | |
3858 | =head2 COMPILER WARNINGS |
4445 | =head2 COMPILER WARNINGS |
3859 | |
4446 | |
3860 | Depending on your compiler and compiler settings, you might get no or a |
4447 | Depending on your compiler and compiler settings, you might get no or a |
… | |
… | |
3871 | maintainable. |
4458 | maintainable. |
3872 | |
4459 | |
3873 | And of course, some compiler warnings are just plain stupid, or simply |
4460 | And of course, some compiler warnings are just plain stupid, or simply |
3874 | wrong (because they don't actually warn about the condition their message |
4461 | wrong (because they don't actually warn about the condition their message |
3875 | seems to warn about). For example, certain older gcc versions had some |
4462 | seems to warn about). For example, certain older gcc versions had some |
3876 | warnings that resulted an extreme number of false positives. These have |
4463 | warnings that resulted in an extreme number of false positives. These have |
3877 | been fixed, but some people still insist on making code warn-free with |
4464 | been fixed, but some people still insist on making code warn-free with |
3878 | such buggy versions. |
4465 | such buggy versions. |
3879 | |
4466 | |
3880 | While libev is written to generate as few warnings as possible, |
4467 | While libev is written to generate as few warnings as possible, |
3881 | "warn-free" code is not a goal, and it is recommended not to build libev |
4468 | "warn-free" code is not a goal, and it is recommended not to build libev |
… | |
… | |
3917 | I suggest using suppression lists. |
4504 | I suggest using suppression lists. |
3918 | |
4505 | |
3919 | |
4506 | |
3920 | =head1 PORTABILITY NOTES |
4507 | =head1 PORTABILITY NOTES |
3921 | |
4508 | |
|
|
4509 | =head2 GNU/LINUX 32 BIT LIMITATIONS |
|
|
4510 | |
|
|
4511 | GNU/Linux is the only common platform that supports 64 bit file/large file |
|
|
4512 | interfaces but I<disables> them by default. |
|
|
4513 | |
|
|
4514 | That means that libev compiled in the default environment doesn't support |
|
|
4515 | files larger than 2GiB or so, which mainly affects C<ev_stat> watchers. |
|
|
4516 | |
|
|
4517 | Unfortunately, many programs try to work around this GNU/Linux issue |
|
|
4518 | by enabling the large file API, which makes them incompatible with the |
|
|
4519 | standard libev compiled for their system. |
|
|
4520 | |
|
|
4521 | Likewise, libev cannot enable the large file API itself as this would |
|
|
4522 | suddenly make it incompatible to the default compile time environment, |
|
|
4523 | i.e. all programs not using special compile switches. |
|
|
4524 | |
|
|
4525 | =head2 OS/X AND DARWIN BUGS |
|
|
4526 | |
|
|
4527 | The whole thing is a bug if you ask me - basically any system interface |
|
|
4528 | you touch is broken, whether it is locales, poll, kqueue or even the |
|
|
4529 | OpenGL drivers. |
|
|
4530 | |
|
|
4531 | =head3 C<kqueue> is buggy |
|
|
4532 | |
|
|
4533 | The kqueue syscall is broken in all known versions - most versions support |
|
|
4534 | only sockets, many support pipes. |
|
|
4535 | |
|
|
4536 | Libev tries to work around this by not using C<kqueue> by default on this |
|
|
4537 | rotten platform, but of course you can still ask for it when creating a |
|
|
4538 | loop - embedding a socket-only kqueue loop into a select-based one is |
|
|
4539 | probably going to work well. |
|
|
4540 | |
|
|
4541 | =head3 C<poll> is buggy |
|
|
4542 | |
|
|
4543 | Instead of fixing C<kqueue>, Apple replaced their (working) C<poll> |
|
|
4544 | implementation by something calling C<kqueue> internally around the 10.5.6 |
|
|
4545 | release, so now C<kqueue> I<and> C<poll> are broken. |
|
|
4546 | |
|
|
4547 | Libev tries to work around this by not using C<poll> by default on |
|
|
4548 | this rotten platform, but of course you can still ask for it when creating |
|
|
4549 | a loop. |
|
|
4550 | |
|
|
4551 | =head3 C<select> is buggy |
|
|
4552 | |
|
|
4553 | All that's left is C<select>, and of course Apple found a way to fuck this |
|
|
4554 | one up as well: On OS/X, C<select> actively limits the number of file |
|
|
4555 | descriptors you can pass in to 1024 - your program suddenly crashes when |
|
|
4556 | you use more. |
|
|
4557 | |
|
|
4558 | There is an undocumented "workaround" for this - defining |
|
|
4559 | C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should> |
|
|
4560 | work on OS/X. |
|
|
4561 | |
|
|
4562 | =head2 SOLARIS PROBLEMS AND WORKAROUNDS |
|
|
4563 | |
|
|
4564 | =head3 C<errno> reentrancy |
|
|
4565 | |
|
|
4566 | The default compile environment on Solaris is unfortunately so |
|
|
4567 | thread-unsafe that you can't even use components/libraries compiled |
|
|
4568 | without C<-D_REENTRANT> in a threaded program, which, of course, isn't |
|
|
4569 | defined by default. A valid, if stupid, implementation choice. |
|
|
4570 | |
|
|
4571 | If you want to use libev in threaded environments you have to make sure |
|
|
4572 | it's compiled with C<_REENTRANT> defined. |
|
|
4573 | |
|
|
4574 | =head3 Event port backend |
|
|
4575 | |
|
|
4576 | The scalable event interface for Solaris is called "event |
|
|
4577 | ports". Unfortunately, this mechanism is very buggy in all major |
|
|
4578 | releases. If you run into high CPU usage, your program freezes or you get |
|
|
4579 | a large number of spurious wakeups, make sure you have all the relevant |
|
|
4580 | and latest kernel patches applied. No, I don't know which ones, but there |
|
|
4581 | are multiple ones to apply, and afterwards, event ports actually work |
|
|
4582 | great. |
|
|
4583 | |
|
|
4584 | If you can't get it to work, you can try running the program by setting |
|
|
4585 | the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and |
|
|
4586 | C<select> backends. |
|
|
4587 | |
|
|
4588 | =head2 AIX POLL BUG |
|
|
4589 | |
|
|
4590 | AIX unfortunately has a broken C<poll.h> header. Libev works around |
|
|
4591 | this by trying to avoid the poll backend altogether (i.e. it's not even |
|
|
4592 | compiled in), which normally isn't a big problem as C<select> works fine |
|
|
4593 | with large bitsets on AIX, and AIX is dead anyway. |
|
|
4594 | |
3922 | =head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
4595 | =head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
|
|
4596 | |
|
|
4597 | =head3 General issues |
3923 | |
4598 | |
3924 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
4599 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
3925 | requires, and its I/O model is fundamentally incompatible with the POSIX |
4600 | requires, and its I/O model is fundamentally incompatible with the POSIX |
3926 | model. Libev still offers limited functionality on this platform in |
4601 | model. Libev still offers limited functionality on this platform in |
3927 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
4602 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
3928 | descriptors. This only applies when using Win32 natively, not when using |
4603 | descriptors. This only applies when using Win32 natively, not when using |
3929 | e.g. cygwin. |
4604 | e.g. cygwin. Actually, it only applies to the microsofts own compilers, |
|
|
4605 | as every compielr comes with a slightly differently broken/incompatible |
|
|
4606 | environment. |
3930 | |
4607 | |
3931 | Lifting these limitations would basically require the full |
4608 | Lifting these limitations would basically require the full |
3932 | re-implementation of the I/O system. If you are into these kinds of |
4609 | re-implementation of the I/O system. If you are into this kind of thing, |
3933 | things, then note that glib does exactly that for you in a very portable |
4610 | then note that glib does exactly that for you in a very portable way (note |
3934 | way (note also that glib is the slowest event library known to man). |
4611 | also that glib is the slowest event library known to man). |
3935 | |
4612 | |
3936 | There is no supported compilation method available on windows except |
4613 | There is no supported compilation method available on windows except |
3937 | embedding it into other applications. |
4614 | embedding it into other applications. |
|
|
4615 | |
|
|
4616 | Sensible signal handling is officially unsupported by Microsoft - libev |
|
|
4617 | tries its best, but under most conditions, signals will simply not work. |
3938 | |
4618 | |
3939 | Not a libev limitation but worth mentioning: windows apparently doesn't |
4619 | Not a libev limitation but worth mentioning: windows apparently doesn't |
3940 | accept large writes: instead of resulting in a partial write, windows will |
4620 | accept large writes: instead of resulting in a partial write, windows will |
3941 | either accept everything or return C<ENOBUFS> if the buffer is too large, |
4621 | either accept everything or return C<ENOBUFS> if the buffer is too large, |
3942 | so make sure you only write small amounts into your sockets (less than a |
4622 | so make sure you only write small amounts into your sockets (less than a |
… | |
… | |
3947 | the abysmal performance of winsockets, using a large number of sockets |
4627 | the abysmal performance of winsockets, using a large number of sockets |
3948 | is not recommended (and not reasonable). If your program needs to use |
4628 | is not recommended (and not reasonable). If your program needs to use |
3949 | more than a hundred or so sockets, then likely it needs to use a totally |
4629 | more than a hundred or so sockets, then likely it needs to use a totally |
3950 | different implementation for windows, as libev offers the POSIX readiness |
4630 | different implementation for windows, as libev offers the POSIX readiness |
3951 | notification model, which cannot be implemented efficiently on windows |
4631 | notification model, which cannot be implemented efficiently on windows |
3952 | (Microsoft monopoly games). |
4632 | (due to Microsoft monopoly games). |
3953 | |
4633 | |
3954 | A typical way to use libev under windows is to embed it (see the embedding |
4634 | A typical way to use libev under windows is to embed it (see the embedding |
3955 | section for details) and use the following F<evwrap.h> header file instead |
4635 | section for details) and use the following F<evwrap.h> header file instead |
3956 | of F<ev.h>: |
4636 | of F<ev.h>: |
3957 | |
4637 | |
… | |
… | |
3964 | you do I<not> compile the F<ev.c> or any other embedded source files!): |
4644 | you do I<not> compile the F<ev.c> or any other embedded source files!): |
3965 | |
4645 | |
3966 | #include "evwrap.h" |
4646 | #include "evwrap.h" |
3967 | #include "ev.c" |
4647 | #include "ev.c" |
3968 | |
4648 | |
3969 | =over 4 |
|
|
3970 | |
|
|
3971 | =item The winsocket select function |
4649 | =head3 The winsocket C<select> function |
3972 | |
4650 | |
3973 | The winsocket C<select> function doesn't follow POSIX in that it |
4651 | The winsocket C<select> function doesn't follow POSIX in that it |
3974 | requires socket I<handles> and not socket I<file descriptors> (it is |
4652 | requires socket I<handles> and not socket I<file descriptors> (it is |
3975 | also extremely buggy). This makes select very inefficient, and also |
4653 | also extremely buggy). This makes select very inefficient, and also |
3976 | requires a mapping from file descriptors to socket handles (the Microsoft |
4654 | requires a mapping from file descriptors to socket handles (the Microsoft |
… | |
… | |
3985 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
4663 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
3986 | |
4664 | |
3987 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
4665 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
3988 | complexity in the O(n²) range when using win32. |
4666 | complexity in the O(n²) range when using win32. |
3989 | |
4667 | |
3990 | =item Limited number of file descriptors |
4668 | =head3 Limited number of file descriptors |
3991 | |
4669 | |
3992 | Windows has numerous arbitrary (and low) limits on things. |
4670 | Windows has numerous arbitrary (and low) limits on things. |
3993 | |
4671 | |
3994 | Early versions of winsocket's select only supported waiting for a maximum |
4672 | Early versions of winsocket's select only supported waiting for a maximum |
3995 | of C<64> handles (probably owning to the fact that all windows kernels |
4673 | of C<64> handles (probably owning to the fact that all windows kernels |
3996 | can only wait for C<64> things at the same time internally; Microsoft |
4674 | can only wait for C<64> things at the same time internally; Microsoft |
3997 | recommends spawning a chain of threads and wait for 63 handles and the |
4675 | recommends spawning a chain of threads and wait for 63 handles and the |
3998 | previous thread in each. Great). |
4676 | previous thread in each. Sounds great!). |
3999 | |
4677 | |
4000 | Newer versions support more handles, but you need to define C<FD_SETSIZE> |
4678 | Newer versions support more handles, but you need to define C<FD_SETSIZE> |
4001 | to some high number (e.g. C<2048>) before compiling the winsocket select |
4679 | to some high number (e.g. C<2048>) before compiling the winsocket select |
4002 | call (which might be in libev or elsewhere, for example, perl does its own |
4680 | call (which might be in libev or elsewhere, for example, perl and many |
4003 | select emulation on windows). |
4681 | other interpreters do their own select emulation on windows). |
4004 | |
4682 | |
4005 | Another limit is the number of file descriptors in the Microsoft runtime |
4683 | Another limit is the number of file descriptors in the Microsoft runtime |
4006 | libraries, which by default is C<64> (there must be a hidden I<64> fetish |
4684 | libraries, which by default is C<64> (there must be a hidden I<64> |
4007 | or something like this inside Microsoft). You can increase this by calling |
4685 | fetish or something like this inside Microsoft). You can increase this |
4008 | C<_setmaxstdio>, which can increase this limit to C<2048> (another |
4686 | by calling C<_setmaxstdio>, which can increase this limit to C<2048> |
4009 | arbitrary limit), but is broken in many versions of the Microsoft runtime |
4687 | (another arbitrary limit), but is broken in many versions of the Microsoft |
4010 | libraries. |
|
|
4011 | |
|
|
4012 | This might get you to about C<512> or C<2048> sockets (depending on |
4688 | runtime libraries. This might get you to about C<512> or C<2048> sockets |
4013 | windows version and/or the phase of the moon). To get more, you need to |
4689 | (depending on windows version and/or the phase of the moon). To get more, |
4014 | wrap all I/O functions and provide your own fd management, but the cost of |
4690 | you need to wrap all I/O functions and provide your own fd management, but |
4015 | calling select (O(n²)) will likely make this unworkable. |
4691 | the cost of calling select (O(n²)) will likely make this unworkable. |
4016 | |
|
|
4017 | =back |
|
|
4018 | |
4692 | |
4019 | =head2 PORTABILITY REQUIREMENTS |
4693 | =head2 PORTABILITY REQUIREMENTS |
4020 | |
4694 | |
4021 | In addition to a working ISO-C implementation and of course the |
4695 | In addition to a working ISO-C implementation and of course the |
4022 | backend-specific APIs, libev relies on a few additional extensions: |
4696 | backend-specific APIs, libev relies on a few additional extensions: |
… | |
… | |
4061 | watchers. |
4735 | watchers. |
4062 | |
4736 | |
4063 | =item C<double> must hold a time value in seconds with enough accuracy |
4737 | =item C<double> must hold a time value in seconds with enough accuracy |
4064 | |
4738 | |
4065 | The type C<double> is used to represent timestamps. It is required to |
4739 | The type C<double> is used to represent timestamps. It is required to |
4066 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
4740 | have at least 51 bits of mantissa (and 9 bits of exponent), which is |
4067 | enough for at least into the year 4000. This requirement is fulfilled by |
4741 | good enough for at least into the year 4000 with millisecond accuracy |
|
|
4742 | (the design goal for libev). This requirement is overfulfilled by |
4068 | implementations implementing IEEE 754 (basically all existing ones). |
4743 | implementations using IEEE 754, which is basically all existing ones. With |
|
|
4744 | IEEE 754 doubles, you get microsecond accuracy until at least 2200. |
4069 | |
4745 | |
4070 | =back |
4746 | =back |
4071 | |
4747 | |
4072 | If you know of other additional requirements drop me a note. |
4748 | If you know of other additional requirements drop me a note. |
4073 | |
4749 | |
… | |
… | |
4141 | involves iterating over all running async watchers or all signal numbers. |
4817 | involves iterating over all running async watchers or all signal numbers. |
4142 | |
4818 | |
4143 | =back |
4819 | =back |
4144 | |
4820 | |
4145 | |
4821 | |
|
|
4822 | =head1 PORTING FROM LIBEV 3.X TO 4.X |
|
|
4823 | |
|
|
4824 | The major version 4 introduced some minor incompatible changes to the API. |
|
|
4825 | |
|
|
4826 | At the moment, the C<ev.h> header file tries to implement superficial |
|
|
4827 | compatibility, so most programs should still compile. Those might be |
|
|
4828 | removed in later versions of libev, so better update early than late. |
|
|
4829 | |
|
|
4830 | =over 4 |
|
|
4831 | |
|
|
4832 | =item function/symbol renames |
|
|
4833 | |
|
|
4834 | A number of functions and symbols have been renamed: |
|
|
4835 | |
|
|
4836 | ev_loop => ev_run |
|
|
4837 | EVLOOP_NONBLOCK => EVRUN_NOWAIT |
|
|
4838 | EVLOOP_ONESHOT => EVRUN_ONCE |
|
|
4839 | |
|
|
4840 | ev_unloop => ev_break |
|
|
4841 | EVUNLOOP_CANCEL => EVBREAK_CANCEL |
|
|
4842 | EVUNLOOP_ONE => EVBREAK_ONE |
|
|
4843 | EVUNLOOP_ALL => EVBREAK_ALL |
|
|
4844 | |
|
|
4845 | EV_TIMEOUT => EV_TIMER |
|
|
4846 | |
|
|
4847 | ev_loop_count => ev_iteration |
|
|
4848 | ev_loop_depth => ev_depth |
|
|
4849 | ev_loop_verify => ev_verify |
|
|
4850 | |
|
|
4851 | Most functions working on C<struct ev_loop> objects don't have an |
|
|
4852 | C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and |
|
|
4853 | associated constants have been renamed to not collide with the C<struct |
|
|
4854 | ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme |
|
|
4855 | as all other watcher types. Note that C<ev_loop_fork> is still called |
|
|
4856 | C<ev_loop_fork> because it would otherwise clash with the C<ev_fork> |
|
|
4857 | typedef. |
|
|
4858 | |
|
|
4859 | =item C<EV_COMPAT3> backwards compatibility mechanism |
|
|
4860 | |
|
|
4861 | The backward compatibility mechanism can be controlled by |
|
|
4862 | C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING> |
|
|
4863 | section. |
|
|
4864 | |
|
|
4865 | =item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES> |
|
|
4866 | |
|
|
4867 | The preprocessor symbol C<EV_MINIMAL> has been replaced by a different |
|
|
4868 | mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile |
|
|
4869 | and work, but the library code will of course be larger. |
|
|
4870 | |
|
|
4871 | =back |
|
|
4872 | |
|
|
4873 | |
4146 | =head1 GLOSSARY |
4874 | =head1 GLOSSARY |
4147 | |
4875 | |
4148 | =over 4 |
4876 | =over 4 |
4149 | |
4877 | |
4150 | =item active |
4878 | =item active |
… | |
… | |
4171 | A change of state of some external event, such as data now being available |
4899 | A change of state of some external event, such as data now being available |
4172 | for reading on a file descriptor, time having passed or simply not having |
4900 | for reading on a file descriptor, time having passed or simply not having |
4173 | any other events happening anymore. |
4901 | any other events happening anymore. |
4174 | |
4902 | |
4175 | In libev, events are represented as single bits (such as C<EV_READ> or |
4903 | In libev, events are represented as single bits (such as C<EV_READ> or |
4176 | C<EV_TIMEOUT>). |
4904 | C<EV_TIMER>). |
4177 | |
4905 | |
4178 | =item event library |
4906 | =item event library |
4179 | |
4907 | |
4180 | A software package implementing an event model and loop. |
4908 | A software package implementing an event model and loop. |
4181 | |
4909 | |