… | |
… | |
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 | |
… | |
… | |
292 | |
292 | |
293 | =back |
293 | =back |
294 | |
294 | |
295 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
295 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
296 | |
296 | |
297 | 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 |
298 | 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 |
299 | I<function>). |
299 | libev 3 had an C<ev_loop> function colliding with the struct name). |
300 | |
300 | |
301 | 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 |
302 | supports signals and child events, and dynamically created loops which do |
302 | supports signals and child events, and dynamically created event loops |
303 | not. |
303 | which do not. |
304 | |
304 | |
305 | =over 4 |
305 | =over 4 |
306 | |
306 | |
307 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
307 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
308 | |
308 | |
… | |
… | |
439 | 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 |
440 | I<different> file descriptors (even already closed ones, so one cannot |
440 | I<different> file descriptors (even already closed ones, so one cannot |
441 | 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 |
442 | on SMP systems). Libev tries to counter these spurious notifications by |
442 | on SMP systems). Libev tries to counter these spurious notifications by |
443 | employing an additional generation counter and comparing that against the |
443 | employing an additional generation counter and comparing that against the |
444 | 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...). |
445 | |
447 | |
446 | 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 |
447 | 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 |
448 | 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 |
449 | 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 |
… | |
… | |
604 | 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 |
605 | earlier call to C<ev_loop_new>. |
607 | earlier call to C<ev_loop_new>. |
606 | |
608 | |
607 | =item ev_default_fork () |
609 | =item ev_default_fork () |
608 | |
610 | |
609 | 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 |
610 | 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 |
611 | 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 |
612 | 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 |
613 | 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 |
614 | 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. |
615 | |
617 | |
616 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
618 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
617 | a fork, I<even if you do not plan to use the loop in the parent>. This is |
619 | a fork, I<even if you do not plan to use the loop in the parent>. This is |
618 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
620 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
619 | during fork. |
621 | during fork. |
620 | |
622 | |
621 | 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 |
622 | process if and only if you want to use the event loop in the child. If you |
624 | process if and only if you want to use the event loop in the child. If |
623 | just fork+exec or create a new loop in the child, you don't have to call |
625 | you just fork+exec or create a new loop in the child, you don't have to |
624 | it at all. |
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). |
625 | |
629 | |
626 | 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 |
627 | 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 |
628 | quite nicely into a call to C<pthread_atfork>: |
632 | quite nicely into a call to C<pthread_atfork>: |
629 | |
633 | |
… | |
… | |
641 | 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 |
642 | otherwise. |
646 | otherwise. |
643 | |
647 | |
644 | =item unsigned int ev_iteration (loop) |
648 | =item unsigned int ev_iteration (loop) |
645 | |
649 | |
646 | Returns the current iteration count for the loop, which is identical to |
650 | Returns the current iteration count for the event loop, which is identical |
647 | 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> |
648 | happily wraps around with enough iterations. |
652 | and happily wraps around with enough iterations. |
649 | |
653 | |
650 | 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 |
651 | "ticks" the number of loop iterations), as it roughly corresponds with |
655 | "ticks" the number of loop iterations), as it roughly corresponds with |
652 | C<ev_prepare> and C<ev_check> calls - and is incremented between the |
656 | C<ev_prepare> and C<ev_check> calls - and is incremented between the |
653 | prepare and check phases. |
657 | prepare and check phases. |
654 | |
658 | |
655 | =item unsigned int ev_depth (loop) |
659 | =item unsigned int ev_depth (loop) |
656 | |
660 | |
657 | Returns the number of times C<ev_loop> was entered minus the number of |
661 | Returns the number of times C<ev_run> was entered minus the number of |
658 | times C<ev_loop> was exited, in other words, the recursion depth. |
662 | times C<ev_run> was exited, in other words, the recursion depth. |
659 | |
663 | |
660 | Outside C<ev_loop>, this number is zero. In a callback, this number is |
664 | Outside C<ev_run>, this number is zero. In a callback, this number is |
661 | C<1>, unless C<ev_loop> was invoked recursively (or from another thread), |
665 | C<1>, unless C<ev_run> was invoked recursively (or from another thread), |
662 | in which case it is higher. |
666 | in which case it is higher. |
663 | |
667 | |
664 | Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread |
668 | Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread |
665 | etc.), doesn't count as "exit" - consider this as a hint to avoid such |
669 | etc.), doesn't count as "exit" - consider this as a hint to avoid such |
666 | ungentleman behaviour unless it's really convenient. |
670 | ungentleman-like behaviour unless it's really convenient. |
667 | |
671 | |
668 | =item unsigned int ev_backend (loop) |
672 | =item unsigned int ev_backend (loop) |
669 | |
673 | |
670 | 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 |
671 | use. |
675 | use. |
… | |
… | |
680 | |
684 | |
681 | =item ev_now_update (loop) |
685 | =item ev_now_update (loop) |
682 | |
686 | |
683 | Establishes the current time by querying the kernel, updating the time |
687 | Establishes the current time by querying the kernel, updating the time |
684 | 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 |
685 | is usually done automatically within C<ev_loop ()>. |
689 | is usually done automatically within C<ev_run ()>. |
686 | |
690 | |
687 | 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 |
688 | 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 |
689 | the current time is a good idea. |
693 | the current time is a good idea. |
690 | |
694 | |
… | |
… | |
692 | |
696 | |
693 | =item ev_suspend (loop) |
697 | =item ev_suspend (loop) |
694 | |
698 | |
695 | =item ev_resume (loop) |
699 | =item ev_resume (loop) |
696 | |
700 | |
697 | 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 |
698 | 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. |
699 | |
703 | |
700 | 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 |
701 | 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 |
702 | 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 |
703 | 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> |
… | |
… | |
714 | without a previous call to C<ev_suspend>. |
718 | without a previous call to C<ev_suspend>. |
715 | |
719 | |
716 | 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 |
717 | event loop time (see C<ev_now_update>). |
721 | event loop time (see C<ev_now_update>). |
718 | |
722 | |
719 | =item ev_loop (loop, int flags) |
723 | =item ev_run (loop, int flags) |
720 | |
724 | |
721 | 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 |
722 | after you have initialised all your watchers and you want to start |
726 | after you have initialised all your watchers and you want to start |
723 | handling 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>. |
724 | |
730 | |
725 | 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 |
726 | 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. |
727 | |
734 | |
728 | 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 |
729 | 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 |
730 | finished (especially in interactive programs), but having a program |
737 | finished (especially in interactive programs), but having a program |
731 | 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 |
732 | 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 |
733 | beauty. |
740 | beauty. |
734 | |
741 | |
735 | 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 |
736 | 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 |
737 | 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 |
738 | 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. |
739 | |
747 | |
740 | 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 |
741 | necessary) and will handle those and any already outstanding ones. It |
749 | necessary) and will handle those and any already outstanding ones. It |
742 | 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 |
743 | 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 |
744 | user-registered callback will be called), and will return after one |
752 | user-registered callback will be called), and will return after one |
745 | iteration of the loop. |
753 | iteration of the loop. |
746 | |
754 | |
747 | 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 |
748 | 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 |
749 | 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 |
750 | usually a better approach for this kind of thing. |
758 | usually a better approach for this kind of thing. |
751 | |
759 | |
752 | Here are the gory details of what C<ev_loop> does: |
760 | Here are the gory details of what C<ev_run> does: |
753 | |
761 | |
|
|
762 | - Increment loop depth. |
|
|
763 | - Reset the ev_break status. |
754 | - Before the first iteration, call any pending watchers. |
764 | - Before the first iteration, call any pending watchers. |
|
|
765 | LOOP: |
755 | * If EVFLAG_FORKCHECK was used, check for a fork. |
766 | - If EVFLAG_FORKCHECK was used, check for a fork. |
756 | - 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. |
757 | - Queue and call all prepare watchers. |
768 | - Queue and call all prepare watchers. |
|
|
769 | - If ev_break was called, goto FINISH. |
758 | - If we have been forked, detach and recreate the kernel state |
770 | - If we have been forked, detach and recreate the kernel state |
759 | as to not disturb the other process. |
771 | as to not disturb the other process. |
760 | - Update the kernel state with all outstanding changes. |
772 | - Update the kernel state with all outstanding changes. |
761 | - Update the "event loop time" (ev_now ()). |
773 | - Update the "event loop time" (ev_now ()). |
762 | - Calculate for how long to sleep or block, if at all |
774 | - Calculate for how long to sleep or block, if at all |
763 | (active idle watchers, EVLOOP_NONBLOCK or not having |
775 | (active idle watchers, EVRUN_NOWAIT or not having |
764 | any active watchers at all will result in not sleeping). |
776 | any active watchers at all will result in not sleeping). |
765 | - 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. |
766 | - Block the process, waiting for any events. |
779 | - Block the process, waiting for any events. |
767 | - Queue all outstanding I/O (fd) events. |
780 | - Queue all outstanding I/O (fd) events. |
768 | - 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. |
769 | - Queue all expired timers. |
782 | - Queue all expired timers. |
770 | - Queue all expired periodics. |
783 | - Queue all expired periodics. |
771 | - Unless any events are pending now, queue all idle watchers. |
784 | - Queue all idle watchers with priority higher than that of pending events. |
772 | - Queue all check watchers. |
785 | - Queue all check watchers. |
773 | - 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). |
774 | 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 |
775 | be handled here by queueing them when their watcher gets executed. |
788 | be handled here by queueing them when their watcher gets executed. |
776 | - 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 |
777 | were used, or there are no active watchers, return, otherwise |
790 | were used, or there are no active watchers, goto FINISH, otherwise |
778 | 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. |
779 | |
796 | |
780 | 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 |
781 | anymore. |
798 | anymore. |
782 | |
799 | |
783 | ... queue jobs here, make sure they register event watchers as long |
800 | ... queue jobs here, make sure they register event watchers as long |
784 | ... 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..) |
785 | ev_loop (my_loop, 0); |
802 | ev_run (my_loop, 0); |
786 | ... jobs done or somebody called unloop. yeah! |
803 | ... jobs done or somebody called unloop. yeah! |
787 | |
804 | |
788 | =item ev_unloop (loop, how) |
805 | =item ev_break (loop, how) |
789 | |
806 | |
790 | 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 |
791 | 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 |
792 | 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 |
793 | 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. |
794 | |
811 | |
795 | 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. |
796 | |
813 | |
797 | It is safe to call C<ev_unloop> from outside any C<ev_loop> calls. |
814 | It is safe to call C<ev_break> from outside any C<ev_run> calls. ##TODO## |
798 | |
815 | |
799 | =item ev_ref (loop) |
816 | =item ev_ref (loop) |
800 | |
817 | |
801 | =item ev_unref (loop) |
818 | =item ev_unref (loop) |
802 | |
819 | |
803 | 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 |
804 | 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 |
805 | 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. |
806 | |
823 | |
807 | This is useful when you have a watcher that you never intend to |
824 | This is useful when you have a watcher that you never intend to |
808 | unregister, but that nevertheless should not keep C<ev_loop> from |
825 | unregister, but that nevertheless should not keep C<ev_run> from |
809 | returning. In such a case, call C<ev_unref> after starting, and C<ev_ref> |
826 | returning. In such a case, call C<ev_unref> after starting, and C<ev_ref> |
810 | before stopping it. |
827 | before stopping it. |
811 | |
828 | |
812 | 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 |
813 | 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 |
814 | 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 |
815 | 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 |
816 | 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 |
817 | 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 |
818 | before, respectively. Note also that libev might stop watchers itself |
835 | before, respectively. Note also that libev might stop watchers itself |
819 | (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> |
820 | in the callback). |
837 | in the callback). |
821 | |
838 | |
822 | 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> |
823 | running when nothing else is active. |
840 | running when nothing else is active. |
824 | |
841 | |
825 | ev_signal exitsig; |
842 | ev_signal exitsig; |
826 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
843 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
827 | ev_signal_start (loop, &exitsig); |
844 | ev_signal_start (loop, &exitsig); |
… | |
… | |
890 | ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
907 | ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
891 | |
908 | |
892 | =item ev_invoke_pending (loop) |
909 | =item ev_invoke_pending (loop) |
893 | |
910 | |
894 | This call will simply invoke all pending watchers while resetting their |
911 | This call will simply invoke all pending watchers while resetting their |
895 | pending state. Normally, C<ev_loop> does this automatically when required, |
912 | pending state. Normally, C<ev_run> does this automatically when required, |
896 | but when overriding the invoke callback this call comes handy. |
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). |
897 | |
918 | |
898 | =item int ev_pending_count (loop) |
919 | =item int ev_pending_count (loop) |
899 | |
920 | |
900 | Returns the number of pending watchers - zero indicates that no watchers |
921 | Returns the number of pending watchers - zero indicates that no watchers |
901 | are pending. |
922 | are pending. |
902 | |
923 | |
903 | =item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P)) |
924 | =item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P)) |
904 | |
925 | |
905 | This overrides the invoke pending functionality of the loop: Instead of |
926 | This overrides the invoke pending functionality of the loop: Instead of |
906 | invoking all pending watchers when there are any, C<ev_loop> will call |
927 | invoking all pending watchers when there are any, C<ev_run> will call |
907 | this callback instead. This is useful, for example, when you want to |
928 | this callback instead. This is useful, for example, when you want to |
908 | invoke the actual watchers inside another context (another thread etc.). |
929 | invoke the actual watchers inside another context (another thread etc.). |
909 | |
930 | |
910 | If you want to reset the callback, use C<ev_invoke_pending> as new |
931 | If you want to reset the callback, use C<ev_invoke_pending> as new |
911 | callback. |
932 | callback. |
… | |
… | |
914 | |
935 | |
915 | Sometimes you want to share the same loop between multiple threads. This |
936 | Sometimes you want to share the same loop between multiple threads. This |
916 | can be done relatively simply by putting mutex_lock/unlock calls around |
937 | can be done relatively simply by putting mutex_lock/unlock calls around |
917 | each call to a libev function. |
938 | each call to a libev function. |
918 | |
939 | |
919 | However, C<ev_loop> can run an indefinite time, so it is not feasible to |
940 | However, C<ev_run> can run an indefinite time, so it is not feasible |
920 | wait for it to return. One way around this is to wake up the loop via |
941 | to wait for it to return. One way around this is to wake up the event |
921 | C<ev_unloop> and C<av_async_send>, another way is to set these I<release> |
942 | loop via C<ev_break> and C<av_async_send>, another way is to set these |
922 | and I<acquire> callbacks on the loop. |
943 | I<release> and I<acquire> callbacks on the loop. |
923 | |
944 | |
924 | When set, then C<release> will be called just before the thread is |
945 | When set, then C<release> will be called just before the thread is |
925 | suspended waiting for new events, and C<acquire> is called just |
946 | suspended waiting for new events, and C<acquire> is called just |
926 | afterwards. |
947 | afterwards. |
927 | |
948 | |
… | |
… | |
930 | |
951 | |
931 | While event loop modifications are allowed between invocations of |
952 | While event loop modifications are allowed between invocations of |
932 | C<release> and C<acquire> (that's their only purpose after all), no |
953 | C<release> and C<acquire> (that's their only purpose after all), no |
933 | modifications done will affect the event loop, i.e. adding watchers will |
954 | modifications done will affect the event loop, i.e. adding watchers will |
934 | have no effect on the set of file descriptors being watched, or the time |
955 | have no effect on the set of file descriptors being watched, or the time |
935 | waited. Use an C<ev_async> watcher to wake up C<ev_loop> when you want it |
956 | waited. Use an C<ev_async> watcher to wake up C<ev_run> when you want it |
936 | to take note of any changes you made. |
957 | to take note of any changes you made. |
937 | |
958 | |
938 | In theory, threads executing C<ev_loop> will be async-cancel safe between |
959 | In theory, threads executing C<ev_run> will be async-cancel safe between |
939 | invocations of C<release> and C<acquire>. |
960 | invocations of C<release> and C<acquire>. |
940 | |
961 | |
941 | See also the locking example in the C<THREADS> section later in this |
962 | See also the locking example in the C<THREADS> section later in this |
942 | document. |
963 | document. |
943 | |
964 | |
… | |
… | |
952 | These two functions can be used to associate arbitrary data with a loop, |
973 | These two functions can be used to associate arbitrary data with a loop, |
953 | and are intended solely for the C<invoke_pending_cb>, C<release> and |
974 | and are intended solely for the C<invoke_pending_cb>, C<release> and |
954 | C<acquire> callbacks described above, but of course can be (ab-)used for |
975 | C<acquire> callbacks described above, but of course can be (ab-)used for |
955 | any other purpose as well. |
976 | any other purpose as well. |
956 | |
977 | |
957 | =item ev_loop_verify (loop) |
978 | =item ev_verify (loop) |
958 | |
979 | |
959 | 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 |
960 | 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 |
961 | through all internal structures and checks them for validity. If anything |
982 | through all internal structures and checks them for validity. If anything |
962 | 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 |
… | |
… | |
973 | |
994 | |
974 | 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 |
975 | 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 |
976 | watchers and C<ev_io_start> for I/O watchers. |
997 | watchers and C<ev_io_start> for I/O watchers. |
977 | |
998 | |
978 | 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 |
979 | 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 |
980 | 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: |
981 | |
1003 | |
982 | 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) |
983 | { |
1005 | { |
984 | ev_io_stop (w); |
1006 | ev_io_stop (w); |
985 | ev_unloop (loop, EVUNLOOP_ALL); |
1007 | ev_break (loop, EVBREAK_ALL); |
986 | } |
1008 | } |
987 | |
1009 | |
988 | struct ev_loop *loop = ev_default_loop (0); |
1010 | struct ev_loop *loop = ev_default_loop (0); |
989 | |
1011 | |
990 | ev_io stdin_watcher; |
1012 | ev_io stdin_watcher; |
991 | |
1013 | |
992 | ev_init (&stdin_watcher, my_cb); |
1014 | ev_init (&stdin_watcher, my_cb); |
993 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
1015 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
994 | ev_io_start (loop, &stdin_watcher); |
1016 | ev_io_start (loop, &stdin_watcher); |
995 | |
1017 | |
996 | ev_loop (loop, 0); |
1018 | ev_run (loop, 0); |
997 | |
1019 | |
998 | 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 |
999 | 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 |
1000 | stack). |
1022 | stack). |
1001 | |
1023 | |
1002 | 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> |
1003 | 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). |
1004 | |
1026 | |
1005 | 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 |
1006 | (watcher *, callback)>, which expects a callback to be provided. This |
1028 | *, callback)>, which expects a callback to be provided. This callback is |
1007 | 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 |
1008 | 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 |
1009 | is readable and/or writable). |
1031 | and/or writable). |
1010 | |
1032 | |
1011 | 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 *, ...) >> |
1012 | 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 |
1013 | 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<< |
1014 | ev_TYPE_init (watcher *, callback, ...) >>. |
1036 | ev_TYPE_init (watcher *, callback, ...) >>. |
… | |
… | |
1065 | |
1087 | |
1066 | =item C<EV_PREPARE> |
1088 | =item C<EV_PREPARE> |
1067 | |
1089 | |
1068 | =item C<EV_CHECK> |
1090 | =item C<EV_CHECK> |
1069 | |
1091 | |
1070 | 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 |
1071 | 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 |
1072 | 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 |
1073 | 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 |
1074 | 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 |
1075 | (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 |
1076 | C<ev_loop> from blocking). |
1098 | C<ev_run> from blocking). |
1077 | |
1099 | |
1078 | =item C<EV_EMBED> |
1100 | =item C<EV_EMBED> |
1079 | |
1101 | |
1080 | 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. |
1081 | |
1103 | |
… | |
… | |
1109 | example it might indicate that a fd is readable or writable, and if your |
1131 | example it might indicate that a fd is readable or writable, and if your |
1110 | callbacks is well-written it can just attempt the operation and cope with |
1132 | callbacks is well-written it can just attempt the operation and cope with |
1111 | the error from read() or write(). This will not work in multi-threaded |
1133 | the error from read() or write(). This will not work in multi-threaded |
1112 | 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 |
1113 | thing, so beware. |
1135 | thing, so beware. |
|
|
1136 | |
|
|
1137 | =back |
|
|
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. |
1114 | |
1195 | |
1115 | =back |
1196 | =back |
1116 | |
1197 | |
1117 | =head2 GENERIC WATCHER FUNCTIONS |
1198 | =head2 GENERIC WATCHER FUNCTIONS |
1118 | |
1199 | |
… | |
… | |
1622 | ... |
1703 | ... |
1623 | struct ev_loop *loop = ev_default_init (0); |
1704 | struct ev_loop *loop = ev_default_init (0); |
1624 | ev_io stdin_readable; |
1705 | ev_io stdin_readable; |
1625 | 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); |
1626 | ev_io_start (loop, &stdin_readable); |
1707 | ev_io_start (loop, &stdin_readable); |
1627 | ev_loop (loop, 0); |
1708 | ev_run (loop, 0); |
1628 | |
1709 | |
1629 | |
1710 | |
1630 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1711 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1631 | |
1712 | |
1632 | 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 |
… | |
… | |
1641 | 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 |
1642 | passed (not I<at>, so on systems with very low-resolution clocks this |
1723 | passed (not I<at>, so on systems with very low-resolution clocks this |
1643 | might introduce a small delay). If multiple timers become ready during the |
1724 | might introduce a small delay). If multiple timers become ready during the |
1644 | same loop iteration then the ones with earlier time-out values are invoked |
1725 | same loop iteration then the ones with earlier time-out values are invoked |
1645 | before ones of the same priority with later time-out values (but this is |
1726 | before ones of the same priority with later time-out values (but this is |
1646 | no longer true when a callback calls C<ev_loop> recursively). |
1727 | no longer true when a callback calls C<ev_run> recursively). |
1647 | |
1728 | |
1648 | =head3 Be smart about timeouts |
1729 | =head3 Be smart about timeouts |
1649 | |
1730 | |
1650 | 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 |
1651 | 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, |
… | |
… | |
1822 | |
1903 | |
1823 | =head3 The special problem of time updates |
1904 | =head3 The special problem of time updates |
1824 | |
1905 | |
1825 | 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 |
1826 | 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 |
1827 | 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 |
1828 | 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 |
1829 | lots of events in one iteration. |
1910 | lots of events in one iteration. |
1830 | |
1911 | |
1831 | The relative timeouts are calculated relative to the C<ev_now ()> |
1912 | The relative timeouts are calculated relative to the C<ev_now ()> |
1832 | 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 |
… | |
… | |
1949 | } |
2030 | } |
1950 | |
2031 | |
1951 | ev_timer mytimer; |
2032 | ev_timer mytimer; |
1952 | 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 */ |
1953 | ev_timer_again (&mytimer); /* start timer */ |
2034 | ev_timer_again (&mytimer); /* start timer */ |
1954 | ev_loop (loop, 0); |
2035 | ev_run (loop, 0); |
1955 | |
2036 | |
1956 | // 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": |
1957 | // reset the timeout to start ticking again at 10 seconds |
2038 | // reset the timeout to start ticking again at 10 seconds |
1958 | ev_timer_again (&mytimer); |
2039 | ev_timer_again (&mytimer); |
1959 | |
2040 | |
… | |
… | |
1985 | |
2066 | |
1986 | 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 |
1987 | 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 |
1988 | 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 |
1989 | 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 |
1990 | (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). |
1991 | |
2072 | |
1992 | =head3 Watcher-Specific Functions and Data Members |
2073 | =head3 Watcher-Specific Functions and Data Members |
1993 | |
2074 | |
1994 | =over 4 |
2075 | =over 4 |
1995 | |
2076 | |
… | |
… | |
2233 | Example: Try to exit cleanly on SIGINT. |
2314 | Example: Try to exit cleanly on SIGINT. |
2234 | |
2315 | |
2235 | static void |
2316 | static void |
2236 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2317 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2237 | { |
2318 | { |
2238 | ev_unloop (loop, EVUNLOOP_ALL); |
2319 | ev_break (loop, EVBREAK_ALL); |
2239 | } |
2320 | } |
2240 | |
2321 | |
2241 | ev_signal signal_watcher; |
2322 | ev_signal signal_watcher; |
2242 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2323 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2243 | ev_signal_start (loop, &signal_watcher); |
2324 | ev_signal_start (loop, &signal_watcher); |
… | |
… | |
2629 | |
2710 | |
2630 | 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: |
2631 | prepare watchers get invoked before the process blocks and check watchers |
2712 | prepare watchers get invoked before the process blocks and check watchers |
2632 | afterwards. |
2713 | afterwards. |
2633 | |
2714 | |
2634 | 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 |
2635 | 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> |
2636 | watchers. Other loops than the current one are fine, however. The |
2717 | watchers. Other loops than the current one are fine, however. The |
2637 | 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 |
2638 | 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, |
2639 | 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 |
… | |
… | |
2807 | |
2888 | |
2808 | if (timeout >= 0) |
2889 | if (timeout >= 0) |
2809 | // create/start timer |
2890 | // create/start timer |
2810 | |
2891 | |
2811 | // poll |
2892 | // poll |
2812 | ev_loop (EV_A_ 0); |
2893 | ev_run (EV_A_ 0); |
2813 | |
2894 | |
2814 | // stop timer again |
2895 | // stop timer again |
2815 | if (timeout >= 0) |
2896 | if (timeout >= 0) |
2816 | ev_timer_stop (EV_A_ &to); |
2897 | ev_timer_stop (EV_A_ &to); |
2817 | |
2898 | |
… | |
… | |
2895 | 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). |
2896 | |
2977 | |
2897 | =item ev_embed_sweep (loop, ev_embed *) |
2978 | =item ev_embed_sweep (loop, ev_embed *) |
2898 | |
2979 | |
2899 | 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 |
2900 | 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 |
2901 | appropriate way for embedded loops. |
2982 | appropriate way for embedded loops. |
2902 | |
2983 | |
2903 | =item struct ev_loop *other [read-only] |
2984 | =item struct ev_loop *other [read-only] |
2904 | |
2985 | |
2905 | The embedded event loop. |
2986 | The embedded event loop. |
… | |
… | |
3011 | =back |
3092 | =back |
3012 | |
3093 | |
3013 | |
3094 | |
3014 | =head2 C<ev_async> - how to wake up an event loop |
3095 | =head2 C<ev_async> - how to wake up an event loop |
3015 | |
3096 | |
3016 | 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 |
3017 | asynchronous sources such as signal handlers (as opposed to multiple event |
3098 | asynchronous sources such as signal handlers (as opposed to multiple event |
3018 | loops - those are of course safe to use in different threads). |
3099 | loops - those are of course safe to use in different threads). |
3019 | |
3100 | |
3020 | Sometimes, however, you need to wake up an event loop you do not control, |
3101 | Sometimes, however, you need to wake up an event loop you do not control, |
3021 | for example because it belongs to another thread. This is what C<ev_async> |
3102 | for example because it belongs to another thread. This is what C<ev_async> |
… | |
… | |
3389 | 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 |
3390 | do this when the watcher is inactive (and not pending either). |
3471 | do this when the watcher is inactive (and not pending either). |
3391 | |
3472 | |
3392 | =item w->set ([arguments]) |
3473 | =item w->set ([arguments]) |
3393 | |
3474 | |
3394 | 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 |
3395 | 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 |
3396 | automatically stopped and restarted when reconfiguring it with this |
3477 | C counterpart, an active watcher gets automatically stopped and restarted |
3397 | method. |
3478 | when reconfiguring it with this method. |
3398 | |
3479 | |
3399 | =item w->start () |
3480 | =item w->start () |
3400 | |
3481 | |
3401 | 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 |
3402 | constructor already stores the event loop. |
3483 | constructor already stores the event loop. |
3403 | |
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 | |
3404 | =item w->stop () |
3491 | =item w->stop () |
3405 | |
3492 | |
3406 | 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. |
3407 | |
3494 | |
3408 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
3495 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
… | |
… | |
3420 | |
3507 | |
3421 | =back |
3508 | =back |
3422 | |
3509 | |
3423 | =back |
3510 | =back |
3424 | |
3511 | |
3425 | 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 |
3426 | the constructor. |
3513 | watchers in the constructor. |
3427 | |
3514 | |
3428 | class myclass |
3515 | class myclass |
3429 | { |
3516 | { |
3430 | 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); |
3431 | ev::idle idle; void idle_cb (ev::idle &w, int revents); |
3519 | ev::idle idle; void idle_cb (ev::idle &w, int revents); |
3432 | |
3520 | |
3433 | myclass (int fd) |
3521 | myclass (int fd) |
3434 | { |
3522 | { |
3435 | io .set <myclass, &myclass::io_cb > (this); |
3523 | io .set <myclass, &myclass::io_cb > (this); |
|
|
3524 | io2 .set <myclass, &myclass::io2_cb > (this); |
3436 | idle.set <myclass, &myclass::idle_cb> (this); |
3525 | idle.set <myclass, &myclass::idle_cb> (this); |
3437 | |
3526 | |
3438 | 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 |
3439 | } |
3531 | } |
3440 | }; |
3532 | }; |
3441 | |
3533 | |
3442 | |
3534 | |
3443 | =head1 OTHER LANGUAGE BINDINGS |
3535 | =head1 OTHER LANGUAGE BINDINGS |
… | |
… | |
3517 | 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, |
3518 | C<EV_A_> is used when other arguments are following. Example: |
3610 | C<EV_A_> is used when other arguments are following. Example: |
3519 | |
3611 | |
3520 | ev_unref (EV_A); |
3612 | ev_unref (EV_A); |
3521 | ev_timer_add (EV_A_ watcher); |
3613 | ev_timer_add (EV_A_ watcher); |
3522 | ev_loop (EV_A_ 0); |
3614 | ev_run (EV_A_ 0); |
3523 | |
3615 | |
3524 | 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, |
3525 | which is often provided by the following macro. |
3617 | which is often provided by the following macro. |
3526 | |
3618 | |
3527 | =item C<EV_P>, C<EV_P_> |
3619 | =item C<EV_P>, C<EV_P_> |
… | |
… | |
3567 | } |
3659 | } |
3568 | |
3660 | |
3569 | ev_check check; |
3661 | ev_check check; |
3570 | ev_check_init (&check, check_cb); |
3662 | ev_check_init (&check, check_cb); |
3571 | ev_check_start (EV_DEFAULT_ &check); |
3663 | ev_check_start (EV_DEFAULT_ &check); |
3572 | ev_loop (EV_DEFAULT_ 0); |
3664 | ev_run (EV_DEFAULT_ 0); |
3573 | |
3665 | |
3574 | =head1 EMBEDDING |
3666 | =head1 EMBEDDING |
3575 | |
3667 | |
3576 | Libev can (and often is) directly embedded into host |
3668 | Libev can (and often is) directly embedded into host |
3577 | applications. Examples of applications that embed it include the Deliantra |
3669 | applications. Examples of applications that embed it include the Deliantra |
… | |
… | |
3668 | to a compiled library. All other symbols change the ABI, which means all |
3760 | to a compiled library. All other symbols change the ABI, which means all |
3669 | users of libev and the libev code itself must be compiled with compatible |
3761 | users of libev and the libev code itself must be compiled with compatible |
3670 | settings. |
3762 | settings. |
3671 | |
3763 | |
3672 | =over 4 |
3764 | =over 4 |
|
|
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. |
3673 | |
3781 | |
3674 | =item EV_STANDALONE (h) |
3782 | =item EV_STANDALONE (h) |
3675 | |
3783 | |
3676 | 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 |
3677 | 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 |
… | |
… | |
4027 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
4135 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
4028 | will be C<0>. |
4136 | will be C<0>. |
4029 | |
4137 | |
4030 | =item EV_VERIFY |
4138 | =item EV_VERIFY |
4031 | |
4139 | |
4032 | Controls how much internal verification (see C<ev_loop_verify ()>) will |
4140 | Controls how much internal verification (see C<ev_verify ()>) will |
4033 | 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 |
4034 | 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 |
4035 | 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 |
4036 | 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 |
4037 | verification code will be called very frequently, which will slow down |
4145 | verification code will be called very frequently, which will slow down |
… | |
… | |
4252 | userdata *u = ev_userdata (EV_A); |
4360 | userdata *u = ev_userdata (EV_A); |
4253 | pthread_mutex_lock (&u->lock); |
4361 | pthread_mutex_lock (&u->lock); |
4254 | } |
4362 | } |
4255 | |
4363 | |
4256 | The event loop thread first acquires the mutex, and then jumps straight |
4364 | The event loop thread first acquires the mutex, and then jumps straight |
4257 | into C<ev_loop>: |
4365 | into C<ev_run>: |
4258 | |
4366 | |
4259 | void * |
4367 | void * |
4260 | l_run (void *thr_arg) |
4368 | l_run (void *thr_arg) |
4261 | { |
4369 | { |
4262 | struct ev_loop *loop = (struct ev_loop *)thr_arg; |
4370 | struct ev_loop *loop = (struct ev_loop *)thr_arg; |
4263 | |
4371 | |
4264 | l_acquire (EV_A); |
4372 | l_acquire (EV_A); |
4265 | pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
4373 | pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
4266 | ev_loop (EV_A_ 0); |
4374 | ev_run (EV_A_ 0); |
4267 | l_release (EV_A); |
4375 | l_release (EV_A); |
4268 | |
4376 | |
4269 | return 0; |
4377 | return 0; |
4270 | } |
4378 | } |
4271 | |
4379 | |
… | |
… | |
4323 | |
4431 | |
4324 | =head3 COROUTINES |
4432 | =head3 COROUTINES |
4325 | |
4433 | |
4326 | Libev is very accommodating to coroutines ("cooperative threads"): |
4434 | Libev is very accommodating to coroutines ("cooperative threads"): |
4327 | libev fully supports nesting calls to its functions from different |
4435 | libev fully supports nesting calls to its functions from different |
4328 | 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 |
4329 | different coroutines, and switch freely between both coroutines running |
4437 | different coroutines, and switch freely between both coroutines running |
4330 | the loop, as long as you don't confuse yourself). The only exception is |
4438 | the loop, as long as you don't confuse yourself). The only exception is |
4331 | that you must not do this from C<ev_periodic> reschedule callbacks. |
4439 | that you must not do this from C<ev_periodic> reschedule callbacks. |
4332 | |
4440 | |
4333 | 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 |
4334 | 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 |
4335 | they do not call any callbacks. |
4443 | they do not call any callbacks. |
4336 | |
4444 | |
4337 | =head2 COMPILER WARNINGS |
4445 | =head2 COMPILER WARNINGS |
4338 | |
4446 | |
4339 | 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 |
… | |
… | |
4423 | =head3 C<kqueue> is buggy |
4531 | =head3 C<kqueue> is buggy |
4424 | |
4532 | |
4425 | The kqueue syscall is broken in all known versions - most versions support |
4533 | The kqueue syscall is broken in all known versions - most versions support |
4426 | only sockets, many support pipes. |
4534 | only sockets, many support pipes. |
4427 | |
4535 | |
|
|
4536 | Libev tries to work around this by not using C<kqueue> by default on |
|
|
4537 | this rotten platform, but of course you can still ask for it when creating |
|
|
4538 | a loop. |
|
|
4539 | |
4428 | =head3 C<poll> is buggy |
4540 | =head3 C<poll> is buggy |
4429 | |
4541 | |
4430 | Instead of fixing C<kqueue>, Apple replaced their (working) C<poll> |
4542 | Instead of fixing C<kqueue>, Apple replaced their (working) C<poll> |
4431 | implementation by something calling C<kqueue> internally around the 10.5.6 |
4543 | implementation by something calling C<kqueue> internally around the 10.5.6 |
4432 | release, so now C<kqueue> I<and> C<poll> are broken. |
4544 | release, so now C<kqueue> I<and> C<poll> are broken. |
4433 | |
4545 | |
4434 | Libev tries to work around this by neither using C<kqueue> nor C<poll> by |
4546 | Libev tries to work around this by not using C<poll> by default on |
4435 | default on this rotten platform, but of course you cna still ask for them |
4547 | this rotten platform, but of course you can still ask for it when creating |
4436 | when creating a loop. |
4548 | a loop. |
4437 | |
4549 | |
4438 | =head3 C<select> is buggy |
4550 | =head3 C<select> is buggy |
4439 | |
4551 | |
4440 | All that's left is C<select>, and of course Apple found a way to fuck this |
4552 | All that's left is C<select>, and of course Apple found a way to fuck this |
4441 | one up as well: On OS/X, C<select> actively limits the number of file |
4553 | one up as well: On OS/X, C<select> actively limits the number of file |
4442 | descriptors you can pass in to 1024 - your program suddenyl crashes when |
4554 | descriptors you can pass in to 1024 - your program suddenly crashes when |
4443 | you use more. |
4555 | you use more. |
4444 | |
4556 | |
4445 | There is an undocumented "workaround" for this - defining |
4557 | There is an undocumented "workaround" for this - defining |
4446 | C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should> |
4558 | C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should> |
4447 | work on OS/X. |
4559 | work on OS/X. |
… | |
… | |
4464 | this mechanism is very buggy. If you run into high CPU usage, your program |
4576 | this mechanism is very buggy. If you run into high CPU usage, your program |
4465 | freezes or you get a large number of spurious wakeups, make sure you have |
4577 | freezes or you get a large number of spurious wakeups, make sure you have |
4466 | all the relevant and latest kernel patches applied. No, I don't know which |
4578 | all the relevant and latest kernel patches applied. No, I don't know which |
4467 | ones, but there are multiple ones. |
4579 | ones, but there are multiple ones. |
4468 | |
4580 | |
4469 | If you can't get it to work, you can try running the program with |
4581 | If you can't get it to work, you can try running the program by setting |
4470 | C<LIBEV_FLAGS=3> to only allow C<poll> and C<select> backends. |
4582 | the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and |
|
|
4583 | C<select> backends. |
4471 | |
4584 | |
4472 | =head2 AIX POLL BUG |
4585 | =head2 AIX POLL BUG |
4473 | |
4586 | |
4474 | AIX unfortunately has a broken C<poll.h> header. Libev works around |
4587 | AIX unfortunately has a broken C<poll.h> header. Libev works around |
4475 | this by trying to avoid the poll backend altogether (i.e. it's not even |
4588 | this by trying to avoid the poll backend altogether (i.e. it's not even |
… | |
… | |
4619 | watchers. |
4732 | watchers. |
4620 | |
4733 | |
4621 | =item C<double> must hold a time value in seconds with enough accuracy |
4734 | =item C<double> must hold a time value in seconds with enough accuracy |
4622 | |
4735 | |
4623 | The type C<double> is used to represent timestamps. It is required to |
4736 | The type C<double> is used to represent timestamps. It is required to |
4624 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
4737 | have at least 51 bits of mantissa (and 9 bits of exponent), which is |
4625 | enough for at least into the year 4000. This requirement is fulfilled by |
4738 | good enough for at least into the year 4000 with millisecond accuracy |
|
|
4739 | (the design goal for libev). This requirement is overfulfilled by |
4626 | implementations implementing IEEE 754, which is basically all existing |
4740 | implementations using IEEE 754, which is basically all existing ones. With |
4627 | ones. With IEEE 754 doubles, you get microsecond accuracy until at least |
4741 | IEEE 754 doubles, you get microsecond accuracy until at least 2200. |
4628 | 2200. |
|
|
4629 | |
4742 | |
4630 | =back |
4743 | =back |
4631 | |
4744 | |
4632 | If you know of other additional requirements drop me a note. |
4745 | If you know of other additional requirements drop me a note. |
4633 | |
4746 | |
… | |
… | |
4711 | compatibility, so most programs should still compile. Those might be |
4824 | compatibility, so most programs should still compile. Those might be |
4712 | removed in later versions of libev, so better update early than late. |
4825 | removed in later versions of libev, so better update early than late. |
4713 | |
4826 | |
4714 | =over 4 |
4827 | =over 4 |
4715 | |
4828 | |
4716 | =item C<ev_loop_count> renamed to C<ev_iteration> |
4829 | =item function/symbol renames |
4717 | |
4830 | |
4718 | =item C<ev_loop_depth> renamed to C<ev_depth> |
4831 | A number of functions and symbols have been renamed: |
4719 | |
4832 | |
4720 | =item C<ev_loop_verify> renamed to C<ev_verify> |
4833 | ev_loop => ev_run |
|
|
4834 | EVLOOP_NONBLOCK => EVRUN_NOWAIT |
|
|
4835 | EVLOOP_ONESHOT => EVRUN_ONCE |
|
|
4836 | |
|
|
4837 | ev_unloop => ev_break |
|
|
4838 | EVUNLOOP_CANCEL => EVBREAK_CANCEL |
|
|
4839 | EVUNLOOP_ONE => EVBREAK_ONE |
|
|
4840 | EVUNLOOP_ALL => EVBREAK_ALL |
|
|
4841 | |
|
|
4842 | EV_TIMEOUT => EV_TIMER |
|
|
4843 | |
|
|
4844 | ev_loop_count => ev_iteration |
|
|
4845 | ev_loop_depth => ev_depth |
|
|
4846 | ev_loop_verify => ev_verify |
4721 | |
4847 | |
4722 | Most functions working on C<struct ev_loop> objects don't have an |
4848 | Most functions working on C<struct ev_loop> objects don't have an |
4723 | C<ev_loop_> prefix, so it was removed. Note that C<ev_loop_fork> is |
4849 | C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and |
|
|
4850 | associated constants have been renamed to not collide with the C<struct |
|
|
4851 | ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme |
|
|
4852 | as all other watcher types. Note that C<ev_loop_fork> is still called |
4724 | still called C<ev_loop_fork> because it would otherwise clash with the |
4853 | C<ev_loop_fork> because it would otherwise clash with the C<ev_fork> |
4725 | C<ev_fork> typedef. |
4854 | typedef. |
4726 | |
4855 | |
4727 | =item C<EV_TIMEOUT> renamed to C<EV_TIMER> in C<revents> |
4856 | =item C<EV_COMPAT3> backwards compatibility mechanism |
4728 | |
4857 | |
4729 | This is a simple rename - all other watcher types use their name |
4858 | The backward compatibility mechanism can be controlled by |
4730 | as revents flag, and now C<ev_timer> does, too. |
4859 | C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING> |
4731 | |
4860 | section. |
4732 | Both C<EV_TIMER> and C<EV_TIMEOUT> symbols were present in 3.x versions |
|
|
4733 | and continue to be present for the foreseeable future, so this is mostly a |
|
|
4734 | documentation change. |
|
|
4735 | |
4861 | |
4736 | =item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES> |
4862 | =item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES> |
4737 | |
4863 | |
4738 | The preprocessor symbol C<EV_MINIMAL> has been replaced by a different |
4864 | The preprocessor symbol C<EV_MINIMAL> has been replaced by a different |
4739 | mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile |
4865 | mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile |