… | |
… | |
299 | |
299 | |
300 | As long as your watcher is active (has been started but not stopped) you |
300 | 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 |
301 | must not touch the values stored in it. Most specifically you must never |
302 | reinitialise it or call its set method. |
302 | reinitialise it or call its set method. |
303 | |
303 | |
304 | You cna check whether an event is active by calling the C<ev_is_active |
304 | 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 |
305 | (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 |
306 | callback for it has not been called yet) you can use the C<ev_is_pending |
307 | (watcher *)> macro. |
307 | (watcher *)> macro. |
308 | |
308 | |
309 | Each and every callback receives the event loop pointer as first, the |
309 | 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 |
310 | registered watcher structure as second, and a bitset of received events as |
311 | third argument. |
311 | third argument. |
312 | |
312 | |
313 | The rceeived events usually include a single bit per event type received |
313 | 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 |
314 | (you can receive multiple events at the same time). The possible bit masks |
315 | are: |
315 | are: |
316 | |
316 | |
317 | =over 4 |
317 | =over 4 |
318 | |
318 | |
… | |
… | |
372 | =back |
372 | =back |
373 | |
373 | |
374 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
374 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
375 | |
375 | |
376 | Each watcher has, by default, a member C<void *data> that you can change |
376 | 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 |
377 | 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 |
378 | 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 |
379 | 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 |
380 | member, you can also "subclass" the watcher type and provide your own |
381 | data: |
381 | data: |
382 | |
382 | |
… | |
… | |
404 | =head1 WATCHER TYPES |
404 | =head1 WATCHER TYPES |
405 | |
405 | |
406 | This section describes each watcher in detail, but will not repeat |
406 | This section describes each watcher in detail, but will not repeat |
407 | information given in the last section. |
407 | information given in the last section. |
408 | |
408 | |
409 | =head2 C<ev_io> - is my file descriptor readable or writable |
409 | =head2 C<ev_io> - is this file descriptor readable or writable |
410 | |
410 | |
411 | I/O watchers check whether a file descriptor is readable or writable |
411 | I/O watchers check whether a file descriptor is readable or writable |
412 | in each iteration of the event loop (This behaviour is called |
412 | in each iteration of the event loop (This behaviour is called |
413 | level-triggering because you keep receiving events as long as the |
413 | 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 |
414 | 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). |
415 | act on the event and neither want to receive future events). |
416 | |
416 | |
417 | In general you can register as many read and/or write event watchers oer |
417 | 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 |
418 | 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 |
419 | 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 |
495 | 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. |
496 | the timer, and again will automatically restart it if need be. |
497 | |
497 | |
498 | =back |
498 | =back |
499 | |
499 | |
500 | =head2 C<ev_periodic> - to cron or not to cron it |
500 | =head2 C<ev_periodic> - to cron or not to cron |
501 | |
501 | |
502 | Periodic watchers are also timers of a kind, but they are very versatile |
502 | Periodic watchers are also timers of a kind, but they are very versatile |
503 | (and unfortunately a bit complex). |
503 | (and unfortunately a bit complex). |
504 | |
504 | |
505 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
505 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
… | |
… | |
544 | |
544 | |
545 | ev_periodic_set (&periodic, 0., 3600., 0); |
545 | ev_periodic_set (&periodic, 0., 3600., 0); |
546 | |
546 | |
547 | This doesn't mean there will always be 3600 seconds in between triggers, |
547 | This doesn't mean there will always be 3600 seconds in between triggers, |
548 | but only that the the callback will be called when the system time shows a |
548 | but only that the the callback will be called when the system time shows a |
549 | full hour (UTC), or more correct, when the system time is evenly divisible |
549 | full hour (UTC), or more correctly, when the system time is evenly divisible |
550 | by 3600. |
550 | by 3600. |
551 | |
551 | |
552 | Another way to think about it (for the mathematically inclined) is that |
552 | Another way to think about it (for the mathematically inclined) is that |
553 | C<ev_periodic> will try to run the callback in this mode at the next possible |
553 | C<ev_periodic> will try to run the callback in this mode at the next possible |
554 | time where C<time = at (mod interval)>, regardless of any time jumps. |
554 | time where C<time = at (mod interval)>, regardless of any time jumps. |
… | |
… | |
559 | ignored. Instead, each time the periodic watcher gets scheduled, the |
559 | ignored. Instead, each time the periodic watcher gets scheduled, the |
560 | reschedule callback will be called with the watcher as first, and the |
560 | reschedule callback will be called with the watcher as first, and the |
561 | current time as second argument. |
561 | current time as second argument. |
562 | |
562 | |
563 | NOTE: I<This callback MUST NOT stop or destroy the periodic or any other |
563 | NOTE: I<This callback MUST NOT stop or destroy the periodic or any other |
564 | periodic watcher, ever, or make any event loop modificstions>. If you need |
564 | periodic watcher, ever, or make any event loop modifications>. If you need |
565 | to stop it, return 1e30 (or so, fudge fudge) and stop it afterwards. |
565 | to stop it, return C<now + 1e30> (or so, fudge fudge) and stop it afterwards. |
566 | |
566 | |
|
|
567 | Also, I<< this callback must always return a time that is later than the |
|
|
568 | passed C<now> value >>. Not even C<now> itself will be ok. |
|
|
569 | |
567 | Its prototype is c<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
570 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
568 | ev_tstamp now)>, e.g.: |
571 | ev_tstamp now)>, e.g.: |
569 | |
572 | |
570 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
573 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
571 | { |
574 | { |
572 | return now + 60.; |
575 | return now + 60.; |
… | |
… | |
598 | Signal watchers will trigger an event when the process receives a specific |
601 | Signal watchers will trigger an event when the process receives a specific |
599 | signal one or more times. Even though signals are very asynchronous, libev |
602 | signal one or more times. Even though signals are very asynchronous, libev |
600 | will try it's best to deliver signals synchronously, i.e. as part of the |
603 | will try it's best to deliver signals synchronously, i.e. as part of the |
601 | normal event processing, like any other event. |
604 | normal event processing, like any other event. |
602 | |
605 | |
603 | You cna configure as many watchers as you like per signal. Only when the |
606 | You can configure as many watchers as you like per signal. Only when the |
604 | first watcher gets started will libev actually register a signal watcher |
607 | first watcher gets started will libev actually register a signal watcher |
605 | with the kernel (thus it coexists with your own signal handlers as long |
608 | with the kernel (thus it coexists with your own signal handlers as long |
606 | as you don't register any with libev). Similarly, when the last signal |
609 | as you don't register any with libev). Similarly, when the last signal |
607 | watcher for a signal is stopped libev will reset the signal handler to |
610 | watcher for a signal is stopped libev will reset the signal handler to |
608 | SIG_DFL (regardless of what it was set to before). |
611 | SIG_DFL (regardless of what it was set to before). |
… | |
… | |
630 | =item ev_child_set (ev_child *, int pid) |
633 | =item ev_child_set (ev_child *, int pid) |
631 | |
634 | |
632 | Configures the watcher to wait for status changes of process C<pid> (or |
635 | Configures the watcher to wait for status changes of process C<pid> (or |
633 | I<any> process if C<pid> is specified as C<0>). The callback can look |
636 | I<any> process if C<pid> is specified as C<0>). The callback can look |
634 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
637 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
635 | the status word (use the macros from C<sys/wait.h>). The C<rpid> member |
638 | the status word (use the macros from C<sys/wait.h> and see your systems |
636 | contains the pid of the process causing the status change. |
639 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
|
|
640 | process causing the status change. |
637 | |
641 | |
638 | =back |
642 | =back |
639 | |
643 | |
640 | =head2 C<ev_idle> - when you've got nothing better to do |
644 | =head2 C<ev_idle> - when you've got nothing better to do |
641 | |
645 | |
642 | Idle watchers trigger events when there are no other I/O or timer (or |
646 | Idle watchers trigger events when there are no other events are pending |
643 | periodic) events pending. That is, as long as your process is busy |
647 | (prepare, check and other idle watchers do not count). That is, as long |
644 | handling sockets or timeouts it will not be called. But when your process |
648 | as your process is busy handling sockets or timeouts (or even signals, |
645 | is idle all idle watchers are being called again and again - until |
649 | imagine) it will not be triggered. But when your process is idle all idle |
|
|
650 | watchers are being called again and again, once per event loop iteration - |
646 | stopped, that is, or your process receives more events. |
651 | until stopped, that is, or your process receives more events and becomes |
|
|
652 | busy. |
647 | |
653 | |
648 | The most noteworthy effect is that as long as any idle watchers are |
654 | The most noteworthy effect is that as long as any idle watchers are |
649 | active, the process will not block when waiting for new events. |
655 | active, the process will not block when waiting for new events. |
650 | |
656 | |
651 | Apart from keeping your process non-blocking (which is a useful |
657 | Apart from keeping your process non-blocking (which is a useful |
… | |
… | |
661 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
667 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
662 | believe me. |
668 | believe me. |
663 | |
669 | |
664 | =back |
670 | =back |
665 | |
671 | |
666 | =head2 prepare and check - your hooks into the event loop |
672 | =head2 C<ev_prepare> and C<ev_check> - your hooks into the event loop |
667 | |
673 | |
668 | Prepare and check watchers usually (but not always) are used in |
674 | Prepare and check watchers are usually (but not always) used in tandem: |
669 | tandom. Prepare watchers get invoked before the process blocks and check |
675 | Prepare watchers get invoked before the process blocks and check watchers |
670 | watchers afterwards. |
676 | afterwards. |
671 | |
677 | |
672 | Their main purpose is to integrate other event mechanisms into libev. This |
678 | Their main purpose is to integrate other event mechanisms into libev. This |
673 | could be used, for example, to track variable changes, implement your own |
679 | could be used, for example, to track variable changes, implement your own |
674 | watchers, integrate net-snmp or a coroutine library and lots more. |
680 | watchers, integrate net-snmp or a coroutine library and lots more. |
675 | |
681 | |
676 | This is done by examining in each prepare call which file descriptors need |
682 | This is done by examining in each prepare call which file descriptors need |
677 | to be watched by the other library, registering C<ev_io> watchers for them |
683 | to be watched by the other library, registering C<ev_io> watchers for |
678 | and starting an C<ev_timer> watcher for any timeouts (many libraries provide |
684 | them and starting an C<ev_timer> watcher for any timeouts (many libraries |
679 | just this functionality). Then, in the check watcher you check for any |
685 | provide just this functionality). Then, in the check watcher you check for |
680 | events that occured (by making your callbacks set soem flags for example) |
686 | any events that occured (by checking the pending status of all watchers |
681 | and call back into the library. |
687 | and stopping them) and call back into the library. The I/O and timer |
|
|
688 | callbacks will never actually be called (but must be valid neverthelles, |
|
|
689 | because you never know, you know?). |
682 | |
690 | |
683 | As another example, the perl Coro module uses these hooks to integrate |
691 | As another example, the Perl Coro module uses these hooks to integrate |
684 | coroutines into libev programs, by yielding to other active coroutines |
692 | coroutines into libev programs, by yielding to other active coroutines |
685 | during each prepare and only letting the process block if no coroutines |
693 | during each prepare and only letting the process block if no coroutines |
686 | are ready to run. |
694 | are ready to run (its actually more complicated, it only runs coroutines |
|
|
695 | with priority higher than the event loop and one lower priority once, |
|
|
696 | using idle watchers to keep the event loop from blocking if lower-priority |
|
|
697 | coroutines exist, thus mapping low-priority coroutines to idle/background |
|
|
698 | tasks). |
687 | |
699 | |
688 | =over 4 |
700 | =over 4 |
689 | |
701 | |
690 | =item ev_prepare_init (ev_prepare *, callback) |
702 | =item ev_prepare_init (ev_prepare *, callback) |
691 | |
703 | |
692 | =item ev_check_init (ev_check *, callback) |
704 | =item ev_check_init (ev_check *, callback) |
693 | |
705 | |
694 | Initialises and configures the prepare or check watcher - they have no |
706 | Initialises and configures the prepare or check watcher - they have no |
695 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
707 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
696 | macros, but using them is utterly, utterly pointless. |
708 | macros, but using them is utterly, utterly and completely pointless. |
697 | |
709 | |
698 | =back |
710 | =back |
699 | |
711 | |
700 | =head1 OTHER FUNCTIONS |
712 | =head1 OTHER FUNCTIONS |
701 | |
713 | |
702 | There are some other fucntions of possible interest. Described. Here. Now. |
714 | There are some other functions of possible interest. Described. Here. Now. |
703 | |
715 | |
704 | =over 4 |
716 | =over 4 |
705 | |
717 | |
706 | =item ev_once (loop, int fd, int events, ev_tstamp timeout, callback) |
718 | =item ev_once (loop, int fd, int events, ev_tstamp timeout, callback) |
707 | |
719 | |
… | |
… | |
709 | callback on whichever event happens first and automatically stop both |
721 | callback on whichever event happens first and automatically stop both |
710 | watchers. This is useful if you want to wait for a single event on an fd |
722 | watchers. This is useful if you want to wait for a single event on an fd |
711 | or timeout without havign to allocate/configure/start/stop/free one or |
723 | or timeout without havign to allocate/configure/start/stop/free one or |
712 | more watchers yourself. |
724 | more watchers yourself. |
713 | |
725 | |
714 | If C<fd> is less than 0, then no I/O watcher will be started and events is |
726 | If C<fd> is less than 0, then no I/O watcher will be started and events |
715 | ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and C<events> set |
727 | is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and |
716 | will be craeted and started. |
728 | C<events> set will be craeted and started. |
717 | |
729 | |
718 | If C<timeout> is less than 0, then no timeout watcher will be |
730 | If C<timeout> is less than 0, then no timeout watcher will be |
719 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and repeat |
731 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
720 | = 0) will be started. |
732 | repeat = 0) will be started. While C<0> is a valid timeout, it is of |
|
|
733 | dubious value. |
721 | |
734 | |
722 | The callback has the type C<void (*cb)(int revents, void *arg)> and |
735 | The callback has the type C<void (*cb)(int revents, void *arg)> and gets |
723 | gets passed an events set (normally a combination of C<EV_ERROR>, C<EV_READ>, |
736 | passed an events set like normal event callbacks (with a combination of |
724 | C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> value passed to C<ev_once>: |
737 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> |
|
|
738 | value passed to C<ev_once>: |
725 | |
739 | |
726 | static void stdin_ready (int revents, void *arg) |
740 | static void stdin_ready (int revents, void *arg) |
727 | { |
741 | { |
728 | if (revents & EV_TIMEOUT) |
742 | if (revents & EV_TIMEOUT) |
729 | /* doh, nothing entered */ |
743 | /* doh, nothing entered */; |
730 | else if (revents & EV_READ) |
744 | else if (revents & EV_READ) |
731 | /* stdin might have data for us, joy! */ |
745 | /* stdin might have data for us, joy! */; |
732 | } |
746 | } |
733 | |
747 | |
734 | ev_once (STDIN_FILENO, EV_READm 10., stdin_ready, 0); |
748 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
735 | |
749 | |
736 | =item ev_feed_event (loop, watcher, int events) |
750 | =item ev_feed_event (loop, watcher, int events) |
737 | |
751 | |
738 | Feeds the given event set into the event loop, as if the specified event |
752 | Feeds the given event set into the event loop, as if the specified event |
739 | has happened for the specified watcher (which must be a pointer to an |
753 | had happened for the specified watcher (which must be a pointer to an |
740 | initialised but not necessarily active event watcher). |
754 | initialised but not necessarily started event watcher). |
741 | |
755 | |
742 | =item ev_feed_fd_event (loop, int fd, int revents) |
756 | =item ev_feed_fd_event (loop, int fd, int revents) |
743 | |
757 | |
744 | Feed an event on the given fd, as if a file descriptor backend detected it. |
758 | Feed an event on the given fd, as if a file descriptor backend detected |
|
|
759 | the given events it. |
745 | |
760 | |
746 | =item ev_feed_signal_event (loop, int signum) |
761 | =item ev_feed_signal_event (loop, int signum) |
747 | |
762 | |
748 | Feed an event as if the given signal occured (loop must be the default loop!). |
763 | Feed an event as if the given signal occured (loop must be the default loop!). |
749 | |
764 | |