… | |
… | |
39 | F<README.embed> in the libev distribution. If libev was configured without |
39 | F<README.embed> in the libev distribution. If libev was configured without |
40 | support for multiple event loops, then all functions taking an initial |
40 | support for multiple event loops, then all functions taking an initial |
41 | argument of name C<loop> (which is always of type C<struct ev_loop *>) |
41 | argument of name C<loop> (which is always of type C<struct ev_loop *>) |
42 | will not have this argument. |
42 | will not have this argument. |
43 | |
43 | |
44 | =head1 TIME AND OTHER GLOBAL FUNCTIONS |
44 | =head1 TIME REPRESENTATION |
45 | |
45 | |
46 | Libev represents time as a single floating point number, representing the |
46 | Libev represents time as a single floating point number, representing the |
47 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
47 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
48 | the beginning of 1970, details are complicated, don't ask). This type is |
48 | the beginning of 1970, details are complicated, don't ask). This type is |
49 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
49 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
50 | to the double type in C. |
50 | to the double type in C. |
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51 | |
|
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52 | =head1 GLOBAL FUNCTIONS |
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53 | |
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54 | These functions can be called anytime, even before initialising the |
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55 | library in any way. |
51 | |
56 | |
52 | =over 4 |
57 | =over 4 |
53 | |
58 | |
54 | =item ev_tstamp ev_time () |
59 | =item ev_tstamp ev_time () |
55 | |
60 | |
… | |
… | |
99 | An event loop is described by a C<struct ev_loop *>. The library knows two |
104 | An event loop is described by a C<struct ev_loop *>. The library knows two |
100 | types of such loops, the I<default> loop, which supports signals and child |
105 | types of such loops, the I<default> loop, which supports signals and child |
101 | events, and dynamically created loops which do not. |
106 | events, and dynamically created loops which do not. |
102 | |
107 | |
103 | If you use threads, a common model is to run the default event loop |
108 | If you use threads, a common model is to run the default event loop |
104 | in your main thread (or in a separate thrad) and for each thread you |
109 | in your main thread (or in a separate thread) and for each thread you |
105 | create, you also create another event loop. Libev itself does no locking |
110 | create, you also create another event loop. Libev itself does no locking |
106 | whatsoever, so if you mix calls to the same event loop in different |
111 | whatsoever, so if you mix calls to the same event loop in different |
107 | threads, make sure you lock (this is usually a bad idea, though, even if |
112 | threads, make sure you lock (this is usually a bad idea, though, even if |
108 | done correctly, because it's hideous and inefficient). |
113 | done correctly, because it's hideous and inefficient). |
109 | |
114 | |
… | |
… | |
299 | |
304 | |
300 | As long as your watcher is active (has been started but not stopped) you |
305 | As long as your watcher is active (has been started but not stopped) you |
301 | must not touch the values stored in it. Most specifically you must never |
306 | must not touch the values stored in it. Most specifically you must never |
302 | reinitialise it or call its set method. |
307 | reinitialise it or call its set method. |
303 | |
308 | |
304 | You cna check whether an event is active by calling the C<ev_is_active |
309 | You can check whether an event is active by calling the C<ev_is_active |
305 | (watcher *)> macro. To see whether an event is outstanding (but the |
310 | (watcher *)> macro. To see whether an event is outstanding (but the |
306 | callback for it has not been called yet) you cna use the C<ev_is_pending |
311 | callback for it has not been called yet) you can use the C<ev_is_pending |
307 | (watcher *)> macro. |
312 | (watcher *)> macro. |
308 | |
313 | |
309 | Each and every callback receives the event loop pointer as first, the |
314 | Each and every callback receives the event loop pointer as first, the |
310 | registered watcher structure as second, and a bitset of received events as |
315 | registered watcher structure as second, and a bitset of received events as |
311 | third argument. |
316 | third argument. |
312 | |
317 | |
313 | The rceeived events usually include a single bit per event type received |
318 | The received events usually include a single bit per event type received |
314 | (you can receive multiple events at the same time). The possible bit masks |
319 | (you can receive multiple events at the same time). The possible bit masks |
315 | are: |
320 | are: |
316 | |
321 | |
317 | =over 4 |
322 | =over 4 |
318 | |
323 | |
… | |
… | |
372 | =back |
377 | =back |
373 | |
378 | |
374 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
379 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
375 | |
380 | |
376 | Each watcher has, by default, a member C<void *data> that you can change |
381 | Each watcher has, by default, a member C<void *data> that you can change |
377 | and read at any time, libev will completely ignore it. This cna be used |
382 | and read at any time, libev will completely ignore it. This can be used |
378 | to associate arbitrary data with your watcher. If you need more data and |
383 | to associate arbitrary data with your watcher. If you need more data and |
379 | don't want to allocate memory and store a pointer to it in that data |
384 | don't want to allocate memory and store a pointer to it in that data |
380 | member, you can also "subclass" the watcher type and provide your own |
385 | member, you can also "subclass" the watcher type and provide your own |
381 | data: |
386 | data: |
382 | |
387 | |
… | |
… | |
409 | =head2 C<ev_io> - is this file descriptor readable or writable |
414 | =head2 C<ev_io> - is this file descriptor readable or writable |
410 | |
415 | |
411 | I/O watchers check whether a file descriptor is readable or writable |
416 | I/O watchers check whether a file descriptor is readable or writable |
412 | in each iteration of the event loop (This behaviour is called |
417 | in each iteration of the event loop (This behaviour is called |
413 | level-triggering because you keep receiving events as long as the |
418 | level-triggering because you keep receiving events as long as the |
414 | condition persists. Remember you cna stop the watcher if you don't want to |
419 | condition persists. Remember you can stop the watcher if you don't want to |
415 | act on the event and neither want to receive future events). |
420 | act on the event and neither want to receive future events). |
416 | |
421 | |
417 | In general you can register as many read and/or write event watchers oer |
422 | In general you can register as many read and/or write event watchers oer |
418 | fd as you want (as long as you don't confuse yourself). Setting all file |
423 | fd as you want (as long as you don't confuse yourself). Setting all file |
419 | descriptors to non-blocking mode is also usually a good idea (but not |
424 | descriptors to non-blocking mode is also usually a good idea (but not |
… | |
… | |
495 | state where you do not expect data to travel on the socket, you can stop |
500 | state where you do not expect data to travel on the socket, you can stop |
496 | the timer, and again will automatically restart it if need be. |
501 | the timer, and again will automatically restart it if need be. |
497 | |
502 | |
498 | =back |
503 | =back |
499 | |
504 | |
500 | =head2 C<ev_periodic> - to cron or not to cron it |
505 | =head2 C<ev_periodic> - to cron or not to cron |
501 | |
506 | |
502 | Periodic watchers are also timers of a kind, but they are very versatile |
507 | Periodic watchers are also timers of a kind, but they are very versatile |
503 | (and unfortunately a bit complex). |
508 | (and unfortunately a bit complex). |
504 | |
509 | |
505 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
510 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
… | |
… | |
558 | In this mode the values for C<interval> and C<at> are both being |
563 | In this mode the values for C<interval> and C<at> are both being |
559 | ignored. Instead, each time the periodic watcher gets scheduled, the |
564 | ignored. Instead, each time the periodic watcher gets scheduled, the |
560 | reschedule callback will be called with the watcher as first, and the |
565 | reschedule callback will be called with the watcher as first, and the |
561 | current time as second argument. |
566 | current time as second argument. |
562 | |
567 | |
563 | NOTE: I<This callback MUST NOT stop or destroy the periodic or any other |
568 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
564 | periodic watcher, ever, or make any event loop modifications>. If you need |
569 | ever, or make any event loop modifications>. If you need to stop it, |
565 | to stop it, return C<now + 1e30> (or so, fudge fudge) and stop it afterwards. |
570 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
566 | |
571 | starting a prepare watcher). |
567 | Also, I<< this callback must always return a time that is later than the |
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568 | passed C<now> value >>. Not even C<now> itself will be ok. |
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569 | |
572 | |
570 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
573 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
571 | ev_tstamp now)>, e.g.: |
574 | ev_tstamp now)>, e.g.: |
572 | |
575 | |
573 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
576 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
… | |
… | |
578 | It must return the next time to trigger, based on the passed time value |
581 | It must return the next time to trigger, based on the passed time value |
579 | (that is, the lowest time value larger than to the second argument). It |
582 | (that is, the lowest time value larger than to the second argument). It |
580 | will usually be called just before the callback will be triggered, but |
583 | will usually be called just before the callback will be triggered, but |
581 | might be called at other times, too. |
584 | might be called at other times, too. |
582 | |
585 | |
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586 | NOTE: I<< This callback must always return a time that is later than the |
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587 | passed C<now> value >>. Not even C<now> itself will do, it I<must> be larger. |
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588 | |
583 | This can be used to create very complex timers, such as a timer that |
589 | This can be used to create very complex timers, such as a timer that |
584 | triggers on each midnight, local time. To do this, you would calculate the |
590 | triggers on each midnight, local time. To do this, you would calculate the |
585 | next midnight after C<now> and return the timestamp value for this. How you do this |
591 | next midnight after C<now> and return the timestamp value for this. How |
586 | is, again, up to you (but it is not trivial). |
592 | you do this is, again, up to you (but it is not trivial, which is the main |
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593 | reason I omitted it as an example). |
587 | |
594 | |
588 | =back |
595 | =back |
589 | |
596 | |
590 | =item ev_periodic_again (loop, ev_periodic *) |
597 | =item ev_periodic_again (loop, ev_periodic *) |
591 | |
598 | |
… | |
… | |
601 | Signal watchers will trigger an event when the process receives a specific |
608 | Signal watchers will trigger an event when the process receives a specific |
602 | signal one or more times. Even though signals are very asynchronous, libev |
609 | signal one or more times. Even though signals are very asynchronous, libev |
603 | will try it's best to deliver signals synchronously, i.e. as part of the |
610 | will try it's best to deliver signals synchronously, i.e. as part of the |
604 | normal event processing, like any other event. |
611 | normal event processing, like any other event. |
605 | |
612 | |
606 | You cna configure as many watchers as you like per signal. Only when the |
613 | You can configure as many watchers as you like per signal. Only when the |
607 | first watcher gets started will libev actually register a signal watcher |
614 | first watcher gets started will libev actually register a signal watcher |
608 | with the kernel (thus it coexists with your own signal handlers as long |
615 | with the kernel (thus it coexists with your own signal handlers as long |
609 | as you don't register any with libev). Similarly, when the last signal |
616 | as you don't register any with libev). Similarly, when the last signal |
610 | watcher for a signal is stopped libev will reset the signal handler to |
617 | watcher for a signal is stopped libev will reset the signal handler to |
611 | SIG_DFL (regardless of what it was set to before). |
618 | SIG_DFL (regardless of what it was set to before). |
… | |
… | |
633 | =item ev_child_set (ev_child *, int pid) |
640 | =item ev_child_set (ev_child *, int pid) |
634 | |
641 | |
635 | Configures the watcher to wait for status changes of process C<pid> (or |
642 | Configures the watcher to wait for status changes of process C<pid> (or |
636 | I<any> process if C<pid> is specified as C<0>). The callback can look |
643 | I<any> process if C<pid> is specified as C<0>). The callback can look |
637 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
644 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
638 | the status word (use the macros from C<sys/wait.h>). The C<rpid> member |
645 | the status word (use the macros from C<sys/wait.h> and see your systems |
639 | contains the pid of the process causing the status change. |
646 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
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|
647 | process causing the status change. |
640 | |
648 | |
641 | =back |
649 | =back |
642 | |
650 | |
643 | =head2 C<ev_idle> - when you've got nothing better to do |
651 | =head2 C<ev_idle> - when you've got nothing better to do |
644 | |
652 | |
645 | Idle watchers trigger events when there are no other I/O or timer (or |
653 | Idle watchers trigger events when there are no other events are pending |
646 | periodic) events pending. That is, as long as your process is busy |
654 | (prepare, check and other idle watchers do not count). That is, as long |
647 | handling sockets or timeouts it will not be called. But when your process |
655 | as your process is busy handling sockets or timeouts (or even signals, |
648 | is idle all idle watchers are being called again and again - until |
656 | imagine) it will not be triggered. But when your process is idle all idle |
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657 | watchers are being called again and again, once per event loop iteration - |
649 | stopped, that is, or your process receives more events. |
658 | until stopped, that is, or your process receives more events and becomes |
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659 | busy. |
650 | |
660 | |
651 | The most noteworthy effect is that as long as any idle watchers are |
661 | The most noteworthy effect is that as long as any idle watchers are |
652 | active, the process will not block when waiting for new events. |
662 | active, the process will not block when waiting for new events. |
653 | |
663 | |
654 | Apart from keeping your process non-blocking (which is a useful |
664 | Apart from keeping your process non-blocking (which is a useful |
… | |
… | |
664 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
674 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
665 | believe me. |
675 | believe me. |
666 | |
676 | |
667 | =back |
677 | =back |
668 | |
678 | |
669 | =head2 prepare and check - your hooks into the event loop |
679 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop |
670 | |
680 | |
671 | Prepare and check watchers usually (but not always) are used in |
681 | Prepare and check watchers are usually (but not always) used in tandem: |
672 | tandom. Prepare watchers get invoked before the process blocks and check |
682 | Prepare watchers get invoked before the process blocks and check watchers |
673 | watchers afterwards. |
683 | afterwards. |
674 | |
684 | |
675 | Their main purpose is to integrate other event mechanisms into libev. This |
685 | Their main purpose is to integrate other event mechanisms into libev. This |
676 | could be used, for example, to track variable changes, implement your own |
686 | could be used, for example, to track variable changes, implement your own |
677 | watchers, integrate net-snmp or a coroutine library and lots more. |
687 | watchers, integrate net-snmp or a coroutine library and lots more. |
678 | |
688 | |
679 | This is done by examining in each prepare call which file descriptors need |
689 | This is done by examining in each prepare call which file descriptors need |
680 | to be watched by the other library, registering C<ev_io> watchers for them |
690 | to be watched by the other library, registering C<ev_io> watchers for |
681 | and starting an C<ev_timer> watcher for any timeouts (many libraries provide |
691 | them and starting an C<ev_timer> watcher for any timeouts (many libraries |
682 | just this functionality). Then, in the check watcher you check for any |
692 | provide just this functionality). Then, in the check watcher you check for |
683 | events that occured (by making your callbacks set soem flags for example) |
693 | any events that occured (by checking the pending status of all watchers |
684 | and call back into the library. |
694 | and stopping them) and call back into the library. The I/O and timer |
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|
695 | callbacks will never actually be called (but must be valid neverthelles, |
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|
696 | because you never know, you know?). |
685 | |
697 | |
686 | As another example, the perl Coro module uses these hooks to integrate |
698 | As another example, the Perl Coro module uses these hooks to integrate |
687 | coroutines into libev programs, by yielding to other active coroutines |
699 | coroutines into libev programs, by yielding to other active coroutines |
688 | during each prepare and only letting the process block if no coroutines |
700 | during each prepare and only letting the process block if no coroutines |
689 | are ready to run. |
701 | are ready to run (its actually more complicated, it only runs coroutines |
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|
702 | with priority higher than the event loop and one lower priority once, |
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|
703 | using idle watchers to keep the event loop from blocking if lower-priority |
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704 | coroutines exist, thus mapping low-priority coroutines to idle/background |
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705 | tasks). |
690 | |
706 | |
691 | =over 4 |
707 | =over 4 |
692 | |
708 | |
693 | =item ev_prepare_init (ev_prepare *, callback) |
709 | =item ev_prepare_init (ev_prepare *, callback) |
694 | |
710 | |
695 | =item ev_check_init (ev_check *, callback) |
711 | =item ev_check_init (ev_check *, callback) |
696 | |
712 | |
697 | Initialises and configures the prepare or check watcher - they have no |
713 | Initialises and configures the prepare or check watcher - they have no |
698 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
714 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
699 | macros, but using them is utterly, utterly pointless. |
715 | macros, but using them is utterly, utterly and completely pointless. |
700 | |
716 | |
701 | =back |
717 | =back |
702 | |
718 | |
703 | =head1 OTHER FUNCTIONS |
719 | =head1 OTHER FUNCTIONS |
704 | |
720 | |
705 | There are some other fucntions of possible interest. Described. Here. Now. |
721 | There are some other functions of possible interest. Described. Here. Now. |
706 | |
722 | |
707 | =over 4 |
723 | =over 4 |
708 | |
724 | |
709 | =item ev_once (loop, int fd, int events, ev_tstamp timeout, callback) |
725 | =item ev_once (loop, int fd, int events, ev_tstamp timeout, callback) |
710 | |
726 | |
… | |
… | |
712 | callback on whichever event happens first and automatically stop both |
728 | callback on whichever event happens first and automatically stop both |
713 | watchers. This is useful if you want to wait for a single event on an fd |
729 | watchers. This is useful if you want to wait for a single event on an fd |
714 | or timeout without havign to allocate/configure/start/stop/free one or |
730 | or timeout without havign to allocate/configure/start/stop/free one or |
715 | more watchers yourself. |
731 | more watchers yourself. |
716 | |
732 | |
717 | If C<fd> is less than 0, then no I/O watcher will be started and events is |
733 | If C<fd> is less than 0, then no I/O watcher will be started and events |
718 | ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and C<events> set |
734 | is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and |
719 | will be craeted and started. |
735 | C<events> set will be craeted and started. |
720 | |
736 | |
721 | If C<timeout> is less than 0, then no timeout watcher will be |
737 | If C<timeout> is less than 0, then no timeout watcher will be |
722 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and repeat |
738 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
723 | = 0) will be started. |
739 | repeat = 0) will be started. While C<0> is a valid timeout, it is of |
|
|
740 | dubious value. |
724 | |
741 | |
725 | The callback has the type C<void (*cb)(int revents, void *arg)> and |
742 | The callback has the type C<void (*cb)(int revents, void *arg)> and gets |
726 | gets passed an events set (normally a combination of C<EV_ERROR>, C<EV_READ>, |
743 | passed an events set like normal event callbacks (with a combination of |
727 | C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> value passed to C<ev_once>: |
744 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> |
|
|
745 | value passed to C<ev_once>: |
728 | |
746 | |
729 | static void stdin_ready (int revents, void *arg) |
747 | static void stdin_ready (int revents, void *arg) |
730 | { |
748 | { |
731 | if (revents & EV_TIMEOUT) |
749 | if (revents & EV_TIMEOUT) |
732 | /* doh, nothing entered */ |
750 | /* doh, nothing entered */; |
733 | else if (revents & EV_READ) |
751 | else if (revents & EV_READ) |
734 | /* stdin might have data for us, joy! */ |
752 | /* stdin might have data for us, joy! */; |
735 | } |
753 | } |
736 | |
754 | |
737 | ev_once (STDIN_FILENO, EV_READm 10., stdin_ready, 0); |
755 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
738 | |
756 | |
739 | =item ev_feed_event (loop, watcher, int events) |
757 | =item ev_feed_event (loop, watcher, int events) |
740 | |
758 | |
741 | Feeds the given event set into the event loop, as if the specified event |
759 | Feeds the given event set into the event loop, as if the specified event |
742 | has happened for the specified watcher (which must be a pointer to an |
760 | had happened for the specified watcher (which must be a pointer to an |
743 | initialised but not necessarily active event watcher). |
761 | initialised but not necessarily started event watcher). |
744 | |
762 | |
745 | =item ev_feed_fd_event (loop, int fd, int revents) |
763 | =item ev_feed_fd_event (loop, int fd, int revents) |
746 | |
764 | |
747 | Feed an event on the given fd, as if a file descriptor backend detected it. |
765 | Feed an event on the given fd, as if a file descriptor backend detected |
|
|
766 | the given events it. |
748 | |
767 | |
749 | =item ev_feed_signal_event (loop, int signum) |
768 | =item ev_feed_signal_event (loop, int signum) |
750 | |
769 | |
751 | Feed an event as if the given signal occured (loop must be the default loop!). |
770 | Feed an event as if the given signal occured (loop must be the default loop!). |
752 | |
771 | |