… | |
… | |
56 | |
56 | |
57 | =over 4 |
57 | =over 4 |
58 | |
58 | |
59 | =item ev_tstamp ev_time () |
59 | =item ev_tstamp ev_time () |
60 | |
60 | |
61 | Returns the current time as libev would use it. |
61 | Returns the current time as libev would use it. Please note that the |
|
|
62 | C<ev_now> function is usually faster and also often returns the timestamp |
|
|
63 | you actually want to know. |
62 | |
64 | |
63 | =item int ev_version_major () |
65 | =item int ev_version_major () |
64 | |
66 | |
65 | =item int ev_version_minor () |
67 | =item int ev_version_minor () |
66 | |
68 | |
… | |
… | |
237 | |
239 | |
238 | This flags value could be used to implement alternative looping |
240 | This flags value could be used to implement alternative looping |
239 | constructs, but the C<prepare> and C<check> watchers provide a better and |
241 | constructs, but the C<prepare> and C<check> watchers provide a better and |
240 | more generic mechanism. |
242 | more generic mechanism. |
241 | |
243 | |
|
|
244 | Here are the gory details of what ev_loop does: |
|
|
245 | |
|
|
246 | 1. If there are no active watchers (reference count is zero), return. |
|
|
247 | 2. Queue and immediately call all prepare watchers. |
|
|
248 | 3. If we have been forked, recreate the kernel state. |
|
|
249 | 4. Update the kernel state with all outstanding changes. |
|
|
250 | 5. Update the "event loop time". |
|
|
251 | 6. Calculate for how long to block. |
|
|
252 | 7. Block the process, waiting for events. |
|
|
253 | 8. Update the "event loop time" and do time jump handling. |
|
|
254 | 9. Queue all outstanding timers. |
|
|
255 | 10. Queue all outstanding periodics. |
|
|
256 | 11. If no events are pending now, queue all idle watchers. |
|
|
257 | 12. Queue all check watchers. |
|
|
258 | 13. Call all queued watchers in reverse order (i.e. check watchers first). |
|
|
259 | 14. If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
|
|
260 | was used, return, otherwise continue with step #1. |
|
|
261 | |
242 | =item ev_unloop (loop, how) |
262 | =item ev_unloop (loop, how) |
243 | |
263 | |
244 | Can be used to make a call to C<ev_loop> return early (but only after it |
264 | Can be used to make a call to C<ev_loop> return early (but only after it |
245 | has processed all outstanding events). The C<how> argument must be either |
265 | has processed all outstanding events). The C<how> argument must be either |
246 | C<EVUNLOOP_ONCE>, which will make the innermost C<ev_loop> call return, or |
266 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
247 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
267 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
248 | |
268 | |
249 | =item ev_ref (loop) |
269 | =item ev_ref (loop) |
250 | |
270 | |
251 | =item ev_unref (loop) |
271 | =item ev_unref (loop) |
… | |
… | |
417 | in each iteration of the event loop (This behaviour is called |
437 | in each iteration of the event loop (This behaviour is called |
418 | level-triggering because you keep receiving events as long as the |
438 | level-triggering because you keep receiving events as long as the |
419 | condition persists. Remember you can stop the watcher if you don't want to |
439 | condition persists. Remember you can stop the watcher if you don't want to |
420 | act on the event and neither want to receive future events). |
440 | act on the event and neither want to receive future events). |
421 | |
441 | |
422 | In general you can register as many read and/or write event watchers oer |
442 | In general you can register as many read and/or write event watchers per |
423 | fd as you want (as long as you don't confuse yourself). Setting all file |
443 | fd as you want (as long as you don't confuse yourself). Setting all file |
424 | descriptors to non-blocking mode is also usually a good idea (but not |
444 | descriptors to non-blocking mode is also usually a good idea (but not |
425 | required if you know what you are doing). |
445 | required if you know what you are doing). |
426 | |
446 | |
427 | You have to be careful with dup'ed file descriptors, though. Some backends |
447 | You have to be careful with dup'ed file descriptors, though. Some backends |
428 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
448 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
429 | descriptors correctly if you register interest in two or more fds pointing |
449 | descriptors correctly if you register interest in two or more fds pointing |
430 | to the same file/socket etc. description. |
450 | to the same underlying file/socket etc. description (that is, they share |
|
|
451 | the same underlying "file open"). |
431 | |
452 | |
432 | If you must do this, then force the use of a known-to-be-good backend |
453 | If you must do this, then force the use of a known-to-be-good backend |
433 | (at the time of this writing, this includes only EVMETHOD_SELECT and |
454 | (at the time of this writing, this includes only EVMETHOD_SELECT and |
434 | EVMETHOD_POLL). |
455 | EVMETHOD_POLL). |
435 | |
456 | |
… | |
… | |
449 | |
470 | |
450 | Timer watchers are simple relative timers that generate an event after a |
471 | Timer watchers are simple relative timers that generate an event after a |
451 | given time, and optionally repeating in regular intervals after that. |
472 | given time, and optionally repeating in regular intervals after that. |
452 | |
473 | |
453 | The timers are based on real time, that is, if you register an event that |
474 | The timers are based on real time, that is, if you register an event that |
454 | times out after an hour and youreset your system clock to last years |
475 | times out after an hour and you reset your system clock to last years |
455 | time, it will still time out after (roughly) and hour. "Roughly" because |
476 | time, it will still time out after (roughly) and hour. "Roughly" because |
456 | detecting time jumps is hard, and soem inaccuracies are unavoidable (the |
477 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
457 | monotonic clock option helps a lot here). |
478 | monotonic clock option helps a lot here). |
458 | |
479 | |
459 | The relative timeouts are calculated relative to the C<ev_now ()> |
480 | The relative timeouts are calculated relative to the C<ev_now ()> |
460 | time. This is usually the right thing as this timestamp refers to the time |
481 | time. This is usually the right thing as this timestamp refers to the time |
461 | of the event triggering whatever timeout you are modifying/starting. If |
482 | of the event triggering whatever timeout you are modifying/starting. If |
462 | you suspect event processing to be delayed and you *need* to base the timeout |
483 | you suspect event processing to be delayed and you I<need> to base the timeout |
463 | ion the current time, use something like this to adjust for this: |
484 | on the current time, use something like this to adjust for this: |
464 | |
485 | |
465 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
486 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
|
|
487 | |
|
|
488 | The callback is guarenteed to be invoked only when its timeout has passed, |
|
|
489 | but if multiple timers become ready during the same loop iteration then |
|
|
490 | order of execution is undefined. |
466 | |
491 | |
467 | =over 4 |
492 | =over 4 |
468 | |
493 | |
469 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
494 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
470 | |
495 | |
… | |
… | |
476 | later, again, and again, until stopped manually. |
501 | later, again, and again, until stopped manually. |
477 | |
502 | |
478 | The timer itself will do a best-effort at avoiding drift, that is, if you |
503 | The timer itself will do a best-effort at avoiding drift, that is, if you |
479 | configure a timer to trigger every 10 seconds, then it will trigger at |
504 | configure a timer to trigger every 10 seconds, then it will trigger at |
480 | exactly 10 second intervals. If, however, your program cannot keep up with |
505 | exactly 10 second intervals. If, however, your program cannot keep up with |
481 | the timer (ecause it takes longer than those 10 seconds to do stuff) the |
506 | the timer (because it takes longer than those 10 seconds to do stuff) the |
482 | timer will not fire more than once per event loop iteration. |
507 | timer will not fire more than once per event loop iteration. |
483 | |
508 | |
484 | =item ev_timer_again (loop) |
509 | =item ev_timer_again (loop) |
485 | |
510 | |
486 | This will act as if the timer timed out and restart it again if it is |
511 | This will act as if the timer timed out and restart it again if it is |
… | |
… | |
517 | again). |
542 | again). |
518 | |
543 | |
519 | They can also be used to implement vastly more complex timers, such as |
544 | They can also be used to implement vastly more complex timers, such as |
520 | triggering an event on eahc midnight, local time. |
545 | triggering an event on eahc midnight, local time. |
521 | |
546 | |
|
|
547 | As with timers, the callback is guarenteed to be invoked only when the |
|
|
548 | time (C<at>) has been passed, but if multiple periodic timers become ready |
|
|
549 | during the same loop iteration then order of execution is undefined. |
|
|
550 | |
522 | =over 4 |
551 | =over 4 |
523 | |
552 | |
524 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
553 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
525 | |
554 | |
526 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
555 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
527 | |
556 | |
528 | Lots of arguments, lets sort it out... There are basically three modes of |
557 | Lots of arguments, lets sort it out... There are basically three modes of |
529 | operation, and we will explain them from simplest to complex: |
558 | operation, and we will explain them from simplest to complex: |
530 | |
|
|
531 | |
559 | |
532 | =over 4 |
560 | =over 4 |
533 | |
561 | |
534 | =item * absolute timer (interval = reschedule_cb = 0) |
562 | =item * absolute timer (interval = reschedule_cb = 0) |
535 | |
563 | |
… | |
… | |
677 | =back |
705 | =back |
678 | |
706 | |
679 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop |
707 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop |
680 | |
708 | |
681 | Prepare and check watchers are usually (but not always) used in tandem: |
709 | Prepare and check watchers are usually (but not always) used in tandem: |
682 | Prepare watchers get invoked before the process blocks and check watchers |
710 | prepare watchers get invoked before the process blocks and check watchers |
683 | afterwards. |
711 | afterwards. |
684 | |
712 | |
685 | Their main purpose is to integrate other event mechanisms into libev. This |
713 | Their main purpose is to integrate other event mechanisms into libev. This |
686 | could be used, for example, to track variable changes, implement your own |
714 | could be used, for example, to track variable changes, implement your own |
687 | watchers, integrate net-snmp or a coroutine library and lots more. |
715 | watchers, integrate net-snmp or a coroutine library and lots more. |
… | |
… | |
690 | to be watched by the other library, registering C<ev_io> watchers for |
718 | to be watched by the other library, registering C<ev_io> watchers for |
691 | them and starting an C<ev_timer> watcher for any timeouts (many libraries |
719 | them and starting an C<ev_timer> watcher for any timeouts (many libraries |
692 | provide just this functionality). Then, in the check watcher you check for |
720 | provide just this functionality). Then, in the check watcher you check for |
693 | any events that occured (by checking the pending status of all watchers |
721 | any events that occured (by checking the pending status of all watchers |
694 | and stopping them) and call back into the library. The I/O and timer |
722 | and stopping them) and call back into the library. The I/O and timer |
695 | callbacks will never actually be called (but must be valid neverthelles, |
723 | callbacks will never actually be called (but must be valid nevertheless, |
696 | because you never know, you know?). |
724 | because you never know, you know?). |
697 | |
725 | |
698 | As another example, the Perl Coro module uses these hooks to integrate |
726 | As another example, the Perl Coro module uses these hooks to integrate |
699 | coroutines into libev programs, by yielding to other active coroutines |
727 | coroutines into libev programs, by yielding to other active coroutines |
700 | during each prepare and only letting the process block if no coroutines |
728 | during each prepare and only letting the process block if no coroutines |
701 | are ready to run (its actually more complicated, it only runs coroutines |
729 | are ready to run (it's actually more complicated: it only runs coroutines |
702 | with priority higher than the event loop and one lower priority once, |
730 | with priority higher than or equal to the event loop and one coroutine |
703 | using idle watchers to keep the event loop from blocking if lower-priority |
731 | of lower priority, but only once, using idle watchers to keep the event |
704 | coroutines exist, thus mapping low-priority coroutines to idle/background |
732 | loop from blocking if lower-priority coroutines are active, thus mapping |
705 | tasks). |
733 | low-priority coroutines to idle/background tasks). |
706 | |
734 | |
707 | =over 4 |
735 | =over 4 |
708 | |
736 | |
709 | =item ev_prepare_init (ev_prepare *, callback) |
737 | =item ev_prepare_init (ev_prepare *, callback) |
710 | |
738 | |
… | |
… | |
725 | =item ev_once (loop, int fd, int events, ev_tstamp timeout, callback) |
753 | =item ev_once (loop, int fd, int events, ev_tstamp timeout, callback) |
726 | |
754 | |
727 | This function combines a simple timer and an I/O watcher, calls your |
755 | This function combines a simple timer and an I/O watcher, calls your |
728 | callback on whichever event happens first and automatically stop both |
756 | callback on whichever event happens first and automatically stop both |
729 | watchers. This is useful if you want to wait for a single event on an fd |
757 | watchers. This is useful if you want to wait for a single event on an fd |
730 | or timeout without havign to allocate/configure/start/stop/free one or |
758 | or timeout without having to allocate/configure/start/stop/free one or |
731 | more watchers yourself. |
759 | more watchers yourself. |
732 | |
760 | |
733 | If C<fd> is less than 0, then no I/O watcher will be started and events |
761 | If C<fd> is less than 0, then no I/O watcher will be started and events |
734 | is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and |
762 | is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and |
735 | C<events> set will be craeted and started. |
763 | C<events> set will be craeted and started. |
… | |
… | |
738 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
766 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
739 | repeat = 0) will be started. While C<0> is a valid timeout, it is of |
767 | repeat = 0) will be started. While C<0> is a valid timeout, it is of |
740 | dubious value. |
768 | dubious value. |
741 | |
769 | |
742 | The callback has the type C<void (*cb)(int revents, void *arg)> and gets |
770 | The callback has the type C<void (*cb)(int revents, void *arg)> and gets |
743 | passed an events set like normal event callbacks (with a combination of |
771 | passed an C<revents> set like normal event callbacks (a combination of |
744 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> |
772 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> |
745 | value passed to C<ev_once>: |
773 | value passed to C<ev_once>: |
746 | |
774 | |
747 | static void stdin_ready (int revents, void *arg) |
775 | static void stdin_ready (int revents, void *arg) |
748 | { |
776 | { |
… | |
… | |
769 | |
797 | |
770 | Feed an event as if the given signal occured (loop must be the default loop!). |
798 | Feed an event as if the given signal occured (loop must be the default loop!). |
771 | |
799 | |
772 | =back |
800 | =back |
773 | |
801 | |
|
|
802 | =head1 LIBEVENT EMULATION |
|
|
803 | |
|
|
804 | Libev offers a compatibility emulation layer for libevent. It cannot |
|
|
805 | emulate the internals of libevent, so here are some usage hints: |
|
|
806 | |
|
|
807 | =over 4 |
|
|
808 | |
|
|
809 | =item * Use it by including <event.h>, as usual. |
|
|
810 | |
|
|
811 | =item * The following members are fully supported: ev_base, ev_callback, |
|
|
812 | ev_arg, ev_fd, ev_res, ev_events. |
|
|
813 | |
|
|
814 | =item * Avoid using ev_flags and the EVLIST_*-macros, while it is |
|
|
815 | maintained by libev, it does not work exactly the same way as in libevent (consider |
|
|
816 | it a private API). |
|
|
817 | |
|
|
818 | =item * Priorities are not currently supported. Initialising priorities |
|
|
819 | will fail and all watchers will have the same priority, even though there |
|
|
820 | is an ev_pri field. |
|
|
821 | |
|
|
822 | =item * Other members are not supported. |
|
|
823 | |
|
|
824 | =item * The libev emulation is I<not> ABI compatible to libevent, you need |
|
|
825 | to use the libev header file and library. |
|
|
826 | |
|
|
827 | =back |
|
|
828 | |
|
|
829 | =head1 C++ SUPPORT |
|
|
830 | |
|
|
831 | TBD. |
|
|
832 | |
774 | =head1 AUTHOR |
833 | =head1 AUTHOR |
775 | |
834 | |
776 | Marc Lehmann <libev@schmorp.de>. |
835 | Marc Lehmann <libev@schmorp.de>. |
777 | |
836 | |