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Revision 1.297 by root, Tue Jun 29 11:49:02 2010 UTC vs.
Revision 1.310 by root, Thu Oct 21 12:32:47 2010 UTC

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
75While this document tries to be as complete as possible in documenting 75While this document tries to be as complete as possible in documenting
76libev, its usage and the rationale behind its design, it is not a tutorial 76libev, its usage and the rationale behind its design, it is not a tutorial
77on event-based programming, nor will it introduce event-based programming 77on event-based programming, nor will it introduce event-based programming
78with libev. 78with libev.
79 79
80Familarity with event based programming techniques in general is assumed 80Familiarity with event based programming techniques in general is assumed
81throughout this document. 81throughout this document.
82 82
83=head1 ABOUT LIBEV 83=head1 ABOUT LIBEV
84 84
85Libev is an event loop: you register interest in certain events (such as a 85Libev is an event loop: you register interest in certain events (such as a
292 292
293=back 293=back
294 294
295=head1 FUNCTIONS CONTROLLING THE EVENT LOOP 295=head1 FUNCTIONS CONTROLLING THE EVENT LOOP
296 296
297An event loop is described by a C<struct ev_loop *> (the C<struct> 297An event loop is described by a C<struct ev_loop *> (the C<struct> is
298is I<not> optional in this case, as there is also an C<ev_loop> 298I<not> optional in case unless libev 3 compatibility is disabled, as libev
299I<function>). 2993 had an C<ev_loop> function colliding with the struct name).
300 300
301The library knows two types of such loops, the I<default> loop, which 301The library knows two types of such loops, the I<default> loop, which
302supports signals and child events, and dynamically created loops which do 302supports signals and child events, and dynamically created event loops
303not. 303which 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
439of course I<doesn't>, and epoll just loves to report events for totally 439of course I<doesn't>, and epoll just loves to report events for totally
440I<different> file descriptors (even already closed ones, so one cannot 440I<different> file descriptors (even already closed ones, so one cannot
441even remove them from the set) than registered in the set (especially 441even remove them from the set) than registered in the set (especially
442on SMP systems). Libev tries to counter these spurious notifications by 442on SMP systems). Libev tries to counter these spurious notifications by
443employing an additional generation counter and comparing that against the 443employing an additional generation counter and comparing that against the
444events to filter out spurious ones, recreating the set when required. 444events to filter out spurious ones, recreating the set when required. Last
445not least, it also refuses to work with some file descriptors which work
446perfectly fine with C<select> (files, many character devices...).
445 447
446While stopping, setting and starting an I/O watcher in the same iteration 448While stopping, setting and starting an I/O watcher in the same iteration
447will result in some caching, there is still a system call per such 449will result in some caching, there is still a system call per such
448incident (because the same I<file descriptor> could point to a different 450incident (because the same I<file descriptor> could point to a different
449I<file description> now), so its best to avoid that. Also, C<dup ()>'ed 451I<file description> now), so its best to avoid that. Also, C<dup ()>'ed
604Like C<ev_default_destroy>, but destroys an event loop created by an 606Like C<ev_default_destroy>, but destroys an event loop created by an
605earlier call to C<ev_loop_new>. 607earlier call to C<ev_loop_new>.
606 608
607=item ev_default_fork () 609=item ev_default_fork ()
608 610
609This function sets a flag that causes subsequent C<ev_loop> iterations 611This function sets a flag that causes subsequent C<ev_run> iterations
610to reinitialise the kernel state for backends that have one. Despite the 612to reinitialise the kernel state for backends that have one. Despite the
611name, you can call it anytime, but it makes most sense after forking, in 613name, you can call it anytime, but it makes most sense after forking, in
612the child process (or both child and parent, but that again makes little 614the child process (or both child and parent, but that again makes little
613sense). You I<must> call it in the child before using any of the libev 615sense). You I<must> call it in the child before using any of the libev
614functions, and it will only take effect at the next C<ev_loop> iteration. 616functions, and it will only take effect at the next C<ev_run> iteration.
615 617
616Again, you I<have> to call it on I<any> loop that you want to re-use after 618Again, you I<have> to call it on I<any> loop that you want to re-use after
617a fork, I<even if you do not plan to use the loop in the parent>. This is 619a fork, I<even if you do not plan to use the loop in the parent>. This is
618because some kernel interfaces *cough* I<kqueue> *cough* do funny things 620because some kernel interfaces *cough* I<kqueue> *cough* do funny things
619during fork. 621during fork.
620 622
621On the other hand, you only need to call this function in the child 623On the other hand, you only need to call this function in the child
622process if and only if you want to use the event loop in the child. If you 624process if and only if you want to use the event loop in the child. If
623just fork+exec or create a new loop in the child, you don't have to call 625you just fork+exec or create a new loop in the child, you don't have to
624it at all. 626call it at all (in fact, C<epoll> is so badly broken that it makes a
627difference, but libev will usually detect this case on its own and do a
628costly reset of the backend).
625 629
626The function itself is quite fast and it's usually not a problem to call 630The function itself is quite fast and it's usually not a problem to call
627it just in case after a fork. To make this easy, the function will fit in 631it just in case after a fork. To make this easy, the function will fit in
628quite nicely into a call to C<pthread_atfork>: 632quite nicely into a call to C<pthread_atfork>:
629 633
641Returns true when the given loop is, in fact, the default loop, and false 645Returns true when the given loop is, in fact, the default loop, and false
642otherwise. 646otherwise.
643 647
644=item unsigned int ev_iteration (loop) 648=item unsigned int ev_iteration (loop)
645 649
646Returns the current iteration count for the loop, which is identical to 650Returns the current iteration count for the event loop, which is identical
647the number of times libev did poll for new events. It starts at C<0> and 651to the number of times libev did poll for new events. It starts at C<0>
648happily wraps around with enough iterations. 652and happily wraps around with enough iterations.
649 653
650This value can sometimes be useful as a generation counter of sorts (it 654This 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
652C<ev_prepare> and C<ev_check> calls - and is incremented between the 656C<ev_prepare> and C<ev_check> calls - and is incremented between the
653prepare and check phases. 657prepare and check phases.
654 658
655=item unsigned int ev_depth (loop) 659=item unsigned int ev_depth (loop)
656 660
657Returns the number of times C<ev_loop> was entered minus the number of 661Returns the number of times C<ev_run> was entered minus the number of
658times C<ev_loop> was exited, in other words, the recursion depth. 662times C<ev_run> was exited, in other words, the recursion depth.
659 663
660Outside C<ev_loop>, this number is zero. In a callback, this number is 664Outside C<ev_run>, this number is zero. In a callback, this number is
661C<1>, unless C<ev_loop> was invoked recursively (or from another thread), 665C<1>, unless C<ev_run> was invoked recursively (or from another thread),
662in which case it is higher. 666in which case it is higher.
663 667
664Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread 668Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread
665etc.), doesn't count as "exit" - consider this as a hint to avoid such 669etc.), doesn't count as "exit" - consider this as a hint to avoid such
666ungentleman behaviour unless it's really convenient. 670ungentleman-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
670Returns one of the C<EVBACKEND_*> flags indicating the event backend in 674Returns one of the C<EVBACKEND_*> flags indicating the event backend in
671use. 675use.
680 684
681=item ev_now_update (loop) 685=item ev_now_update (loop)
682 686
683Establishes the current time by querying the kernel, updating the time 687Establishes the current time by querying the kernel, updating the time
684returned by C<ev_now ()> in the progress. This is a costly operation and 688returned by C<ev_now ()> in the progress. This is a costly operation and
685is usually done automatically within C<ev_loop ()>. 689is usually done automatically within C<ev_run ()>.
686 690
687This function is rarely useful, but when some event callback runs for a 691This function is rarely useful, but when some event callback runs for a
688very long time without entering the event loop, updating libev's idea of 692very long time without entering the event loop, updating libev's idea of
689the current time is a good idea. 693the 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
697These two functions suspend and resume a loop, for use when the loop is 701These two functions suspend and resume an event loop, for use when the
698not used for a while and timeouts should not be processed. 702loop is not used for a while and timeouts should not be processed.
699 703
700A typical use case would be an interactive program such as a game: When 704A typical use case would be an interactive program such as a game: When
701the user presses C<^Z> to suspend the game and resumes it an hour later it 705the user presses C<^Z> to suspend the game and resumes it an hour later it
702would be best to handle timeouts as if no time had actually passed while 706would be best to handle timeouts as if no time had actually passed while
703the program was suspended. This can be achieved by calling C<ev_suspend> 707the program was suspended. This can be achieved by calling C<ev_suspend>
705C<ev_resume> directly afterwards to resume timer processing. 709C<ev_resume> directly afterwards to resume timer processing.
706 710
707Effectively, all C<ev_timer> watchers will be delayed by the time spend 711Effectively, all C<ev_timer> watchers will be delayed by the time spend
708between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers 712between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers
709will be rescheduled (that is, they will lose any events that would have 713will be rescheduled (that is, they will lose any events that would have
710occured while suspended). 714occurred while suspended).
711 715
712After calling C<ev_suspend> you B<must not> call I<any> function on the 716After calling C<ev_suspend> you B<must not> call I<any> function on the
713given loop other than C<ev_resume>, and you B<must not> call C<ev_resume> 717given loop other than C<ev_resume>, and you B<must not> call C<ev_resume>
714without a previous call to C<ev_suspend>. 718without a previous call to C<ev_suspend>.
715 719
716Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the 720Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the
717event loop time (see C<ev_now_update>). 721event 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
721Finally, this is it, the event handler. This function usually is called 725Finally, this is it, the event handler. This function usually is called
722after you have initialised all your watchers and you want to start 726after you have initialised all your watchers and you want to start
723handling events. 727handling events. It will ask the operating system for any new events, call
728the watcher callbacks, an then repeat the whole process indefinitely: This
729is why event loops are called I<loops>.
724 730
725If the flags argument is specified as C<0>, it will not return until 731If the flags argument is specified as C<0>, it will keep handling events
726either no event watchers are active anymore or C<ev_unloop> was called. 732until either no event watchers are active anymore or C<ev_break> was
733called.
727 734
728Please note that an explicit C<ev_unloop> is usually better than 735Please note that an explicit C<ev_break> is usually better than
729relying on all watchers to be stopped when deciding when a program has 736relying on all watchers to be stopped when deciding when a program has
730finished (especially in interactive programs), but having a program 737finished (especially in interactive programs), but having a program
731that automatically loops as long as it has to and no longer by virtue 738that automatically loops as long as it has to and no longer by virtue
732of relying on its watchers stopping correctly, that is truly a thing of 739of relying on its watchers stopping correctly, that is truly a thing of
733beauty. 740beauty.
734 741
735A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle 742A flags value of C<EVRUN_NOWAIT> will look for new events, will handle
736those events and any already outstanding ones, but will not block your 743those events and any already outstanding ones, but will not wait and
737process in case there are no events and will return after one iteration of 744block your process in case there are no events and will return after one
738the loop. 745iteration of the loop. This is sometimes useful to poll and handle new
746events while doing lengthy calculations, to keep the program responsive.
739 747
740A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if 748A flags value of C<EVRUN_ONCE> will look for new events (waiting if
741necessary) and will handle those and any already outstanding ones. It 749necessary) and will handle those and any already outstanding ones. It
742will block your process until at least one new event arrives (which could 750will block your process until at least one new event arrives (which could
743be an event internal to libev itself, so there is no guarantee that a 751be an event internal to libev itself, so there is no guarantee that a
744user-registered callback will be called), and will return after one 752user-registered callback will be called), and will return after one
745iteration of the loop. 753iteration of the loop.
746 754
747This is useful if you are waiting for some external event in conjunction 755This is useful if you are waiting for some external event in conjunction
748with something not expressible using other libev watchers (i.e. "roll your 756with something not expressible using other libev watchers (i.e. "roll your
749own C<ev_loop>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is 757own C<ev_run>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is
750usually a better approach for this kind of thing. 758usually a better approach for this kind of thing.
751 759
752Here are the gory details of what C<ev_loop> does: 760Here 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
780Example: Queue some jobs and then loop until no events are outstanding 797Example: Queue some jobs and then loop until no events are outstanding
781anymore. 798anymore.
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
790Can be used to make a call to C<ev_loop> return early (but only after it 807Can be used to make a call to C<ev_run> return early (but only after it
791has processed all outstanding events). The C<how> argument must be either 808has processed all outstanding events). The C<how> argument must be either
792C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or 809C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or
793C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. 810C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return.
794 811
795This "unloop state" will be cleared when entering C<ev_loop> again. 812This "unloop state" will be cleared when entering C<ev_run> again.
796 813
797It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls. 814It 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
803Ref/unref can be used to add or remove a reference count on the event 820Ref/unref can be used to add or remove a reference count on the event
804loop: Every watcher keeps one reference, and as long as the reference 821loop: Every watcher keeps one reference, and as long as the reference
805count is nonzero, C<ev_loop> will not return on its own. 822count is nonzero, C<ev_run> will not return on its own.
806 823
807This is useful when you have a watcher that you never intend to 824This is useful when you have a watcher that you never intend to
808unregister, but that nevertheless should not keep C<ev_loop> from 825unregister, but that nevertheless should not keep C<ev_run> from
809returning. In such a case, call C<ev_unref> after starting, and C<ev_ref> 826returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>
810before stopping it. 827before stopping it.
811 828
812As an example, libev itself uses this for its internal signal pipe: It 829As an example, libev itself uses this for its internal signal pipe: It
813is not visible to the libev user and should not keep C<ev_loop> from 830is not visible to the libev user and should not keep C<ev_run> from
814exiting if no event watchers registered by it are active. It is also an 831exiting if no event watchers registered by it are active. It is also an
815excellent way to do this for generic recurring timers or from within 832excellent way to do this for generic recurring timers or from within
816third-party libraries. Just remember to I<unref after start> and I<ref 833third-party libraries. Just remember to I<unref after start> and I<ref
817before stop> (but only if the watcher wasn't active before, or was active 834before stop> (but only if the watcher wasn't active before, or was active
818before, respectively. Note also that libev might stop watchers itself 835before, 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>
820in the callback). 837in the callback).
821 838
822Example: Create a signal watcher, but keep it from keeping C<ev_loop> 839Example: Create a signal watcher, but keep it from keeping C<ev_run>
823running when nothing else is active. 840running 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);
872usually doesn't make much sense to set it to a lower value than C<0.01>, 889usually doesn't make much sense to set it to a lower value than C<0.01>,
873as this approaches the timing granularity of most systems. Note that if 890as this approaches the timing granularity of most systems. Note that if
874you do transactions with the outside world and you can't increase the 891you do transactions with the outside world and you can't increase the
875parallelity, then this setting will limit your transaction rate (if you 892parallelity, then this setting will limit your transaction rate (if you
876need to poll once per transaction and the I/O collect interval is 0.01, 893need to poll once per transaction and the I/O collect interval is 0.01,
877then you can't do more than 100 transations per second). 894then you can't do more than 100 transactions per second).
878 895
879Setting the I<timeout collect interval> can improve the opportunity for 896Setting the I<timeout collect interval> can improve the opportunity for
880saving power, as the program will "bundle" timer callback invocations that 897saving power, as the program will "bundle" timer callback invocations that
881are "near" in time together, by delaying some, thus reducing the number of 898are "near" in time together, by delaying some, thus reducing the number of
882times the process sleeps and wakes up again. Another useful technique to 899times the process sleeps and wakes up again. Another useful technique to
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
894This call will simply invoke all pending watchers while resetting their 911This call will simply invoke all pending watchers while resetting their
895pending state. Normally, C<ev_loop> does this automatically when required, 912pending state. Normally, C<ev_run> does this automatically when required,
896but when overriding the invoke callback this call comes handy. 913but when overriding the invoke callback this call comes handy.
897 914
898=item int ev_pending_count (loop) 915=item int ev_pending_count (loop)
899 916
900Returns the number of pending watchers - zero indicates that no watchers 917Returns the number of pending watchers - zero indicates that no watchers
901are pending. 918are pending.
902 919
903=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P)) 920=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))
904 921
905This overrides the invoke pending functionality of the loop: Instead of 922This overrides the invoke pending functionality of the loop: Instead of
906invoking all pending watchers when there are any, C<ev_loop> will call 923invoking all pending watchers when there are any, C<ev_run> will call
907this callback instead. This is useful, for example, when you want to 924this callback instead. This is useful, for example, when you want to
908invoke the actual watchers inside another context (another thread etc.). 925invoke the actual watchers inside another context (another thread etc.).
909 926
910If you want to reset the callback, use C<ev_invoke_pending> as new 927If you want to reset the callback, use C<ev_invoke_pending> as new
911callback. 928callback.
914 931
915Sometimes you want to share the same loop between multiple threads. This 932Sometimes you want to share the same loop between multiple threads. This
916can be done relatively simply by putting mutex_lock/unlock calls around 933can be done relatively simply by putting mutex_lock/unlock calls around
917each call to a libev function. 934each call to a libev function.
918 935
919However, C<ev_loop> can run an indefinite time, so it is not feasible to 936However, C<ev_run> can run an indefinite time, so it is not feasible
920wait for it to return. One way around this is to wake up the loop via 937to wait for it to return. One way around this is to wake up the event
921C<ev_unloop> and C<av_async_send>, another way is to set these I<release> 938loop via C<ev_break> and C<av_async_send>, another way is to set these
922and I<acquire> callbacks on the loop. 939I<release> and I<acquire> callbacks on the loop.
923 940
924When set, then C<release> will be called just before the thread is 941When set, then C<release> will be called just before the thread is
925suspended waiting for new events, and C<acquire> is called just 942suspended waiting for new events, and C<acquire> is called just
926afterwards. 943afterwards.
927 944
930 947
931While event loop modifications are allowed between invocations of 948While event loop modifications are allowed between invocations of
932C<release> and C<acquire> (that's their only purpose after all), no 949C<release> and C<acquire> (that's their only purpose after all), no
933modifications done will affect the event loop, i.e. adding watchers will 950modifications done will affect the event loop, i.e. adding watchers will
934have no effect on the set of file descriptors being watched, or the time 951have no effect on the set of file descriptors being watched, or the time
935waited. Use an C<ev_async> watcher to wake up C<ev_loop> when you want it 952waited. Use an C<ev_async> watcher to wake up C<ev_run> when you want it
936to take note of any changes you made. 953to take note of any changes you made.
937 954
938In theory, threads executing C<ev_loop> will be async-cancel safe between 955In theory, threads executing C<ev_run> will be async-cancel safe between
939invocations of C<release> and C<acquire>. 956invocations of C<release> and C<acquire>.
940 957
941See also the locking example in the C<THREADS> section later in this 958See also the locking example in the C<THREADS> section later in this
942document. 959document.
943 960
952These two functions can be used to associate arbitrary data with a loop, 969These two functions can be used to associate arbitrary data with a loop,
953and are intended solely for the C<invoke_pending_cb>, C<release> and 970and are intended solely for the C<invoke_pending_cb>, C<release> and
954C<acquire> callbacks described above, but of course can be (ab-)used for 971C<acquire> callbacks described above, but of course can be (ab-)used for
955any other purpose as well. 972any other purpose as well.
956 973
957=item ev_loop_verify (loop) 974=item ev_verify (loop)
958 975
959This function only does something when C<EV_VERIFY> support has been 976This function only does something when C<EV_VERIFY> support has been
960compiled in, which is the default for non-minimal builds. It tries to go 977compiled in, which is the default for non-minimal builds. It tries to go
961through all internal structures and checks them for validity. If anything 978through all internal structures and checks them for validity. If anything
962is found to be inconsistent, it will print an error message to standard 979is found to be inconsistent, it will print an error message to standard
980become readable, you would create an C<ev_io> watcher for that: 997become readable, you would create an C<ev_io> watcher for that:
981 998
982 static void my_cb (struct ev_loop *loop, ev_io *w, int revents) 999 static void my_cb (struct ev_loop *loop, ev_io *w, int revents)
983 { 1000 {
984 ev_io_stop (w); 1001 ev_io_stop (w);
985 ev_unloop (loop, EVUNLOOP_ALL); 1002 ev_break (loop, EVBREAK_ALL);
986 } 1003 }
987 1004
988 struct ev_loop *loop = ev_default_loop (0); 1005 struct ev_loop *loop = ev_default_loop (0);
989 1006
990 ev_io stdin_watcher; 1007 ev_io stdin_watcher;
991 1008
992 ev_init (&stdin_watcher, my_cb); 1009 ev_init (&stdin_watcher, my_cb);
993 ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); 1010 ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
994 ev_io_start (loop, &stdin_watcher); 1011 ev_io_start (loop, &stdin_watcher);
995 1012
996 ev_loop (loop, 0); 1013 ev_run (loop, 0);
997 1014
998As you can see, you are responsible for allocating the memory for your 1015As you can see, you are responsible for allocating the memory for your
999watcher structures (and it is I<usually> a bad idea to do this on the 1016watcher structures (and it is I<usually> a bad idea to do this on the
1000stack). 1017stack).
1001 1018
1065 1082
1066=item C<EV_PREPARE> 1083=item C<EV_PREPARE>
1067 1084
1068=item C<EV_CHECK> 1085=item C<EV_CHECK>
1069 1086
1070All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts 1087All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts
1071to gather new events, and all C<ev_check> watchers are invoked just after 1088to gather new events, and all C<ev_check> watchers are invoked just after
1072C<ev_loop> has gathered them, but before it invokes any callbacks for any 1089C<ev_run> has gathered them, but before it invokes any callbacks for any
1073received events. Callbacks of both watcher types can start and stop as 1090received events. Callbacks of both watcher types can start and stop as
1074many watchers as they want, and all of them will be taken into account 1091many 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 1092(for example, a C<ev_prepare> watcher might start an idle watcher to keep
1076C<ev_loop> from blocking). 1093C<ev_run> from blocking).
1077 1094
1078=item C<EV_EMBED> 1095=item C<EV_EMBED>
1079 1096
1080The embedded event loop specified in the C<ev_embed> watcher needs attention. 1097The embedded event loop specified in the C<ev_embed> watcher needs attention.
1081 1098
1380 1397
1381For example, to emulate how many other event libraries handle priorities, 1398For example, to emulate how many other event libraries handle priorities,
1382you can associate an C<ev_idle> watcher to each such watcher, and in 1399you can associate an C<ev_idle> watcher to each such watcher, and in
1383the normal watcher callback, you just start the idle watcher. The real 1400the normal watcher callback, you just start the idle watcher. The real
1384processing is done in the idle watcher callback. This causes libev to 1401processing is done in the idle watcher callback. This causes libev to
1385continously poll and process kernel event data for the watcher, but when 1402continuously poll and process kernel event data for the watcher, but when
1386the lock-out case is known to be rare (which in turn is rare :), this is 1403the lock-out case is known to be rare (which in turn is rare :), this is
1387workable. 1404workable.
1388 1405
1389Usually, however, the lock-out model implemented that way will perform 1406Usually, however, the lock-out model implemented that way will perform
1390miserably under the type of load it was designed to handle. In that case, 1407miserably under the type of load it was designed to handle. In that case,
1468 1485
1469If you cannot use non-blocking mode, then force the use of a 1486If you cannot use non-blocking mode, then force the use of a
1470known-to-be-good backend (at the time of this writing, this includes only 1487known-to-be-good backend (at the time of this writing, this includes only
1471C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file 1488C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file
1472descriptors for which non-blocking operation makes no sense (such as 1489descriptors for which non-blocking operation makes no sense (such as
1473files) - libev doesn't guarentee any specific behaviour in that case. 1490files) - libev doesn't guarantee any specific behaviour in that case.
1474 1491
1475Another thing you have to watch out for is that it is quite easy to 1492Another thing you have to watch out for is that it is quite easy to
1476receive "spurious" readiness notifications, that is your callback might 1493receive "spurious" readiness notifications, that is your callback might
1477be called with C<EV_READ> but a subsequent C<read>(2) will actually block 1494be called with C<EV_READ> but a subsequent C<read>(2) will actually block
1478because there is no data. Not only are some backends known to create a 1495because there is no data. Not only are some backends known to create a
1622 ... 1639 ...
1623 struct ev_loop *loop = ev_default_init (0); 1640 struct ev_loop *loop = ev_default_init (0);
1624 ev_io stdin_readable; 1641 ev_io stdin_readable;
1625 ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); 1642 ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1626 ev_io_start (loop, &stdin_readable); 1643 ev_io_start (loop, &stdin_readable);
1627 ev_loop (loop, 0); 1644 ev_run (loop, 0);
1628 1645
1629 1646
1630=head2 C<ev_timer> - relative and optionally repeating timeouts 1647=head2 C<ev_timer> - relative and optionally repeating timeouts
1631 1648
1632Timer watchers are simple relative timers that generate an event after a 1649Timer watchers are simple relative timers that generate an event after a
1641The callback is guaranteed to be invoked only I<after> its timeout has 1658The callback is guaranteed to be invoked only I<after> its timeout has
1642passed (not I<at>, so on systems with very low-resolution clocks this 1659passed (not I<at>, so on systems with very low-resolution clocks this
1643might introduce a small delay). If multiple timers become ready during the 1660might introduce a small delay). If multiple timers become ready during the
1644same loop iteration then the ones with earlier time-out values are invoked 1661same loop iteration then the ones with earlier time-out values are invoked
1645before ones of the same priority with later time-out values (but this is 1662before ones of the same priority with later time-out values (but this is
1646no longer true when a callback calls C<ev_loop> recursively). 1663no longer true when a callback calls C<ev_run> recursively).
1647 1664
1648=head3 Be smart about timeouts 1665=head3 Be smart about timeouts
1649 1666
1650Many real-world problems involve some kind of timeout, usually for error 1667Many real-world problems involve some kind of timeout, usually for error
1651recovery. A typical example is an HTTP request - if the other side hangs, 1668recovery. A typical example is an HTTP request - if the other side hangs,
1737 ev_tstamp timeout = last_activity + 60.; 1754 ev_tstamp timeout = last_activity + 60.;
1738 1755
1739 // if last_activity + 60. is older than now, we did time out 1756 // if last_activity + 60. is older than now, we did time out
1740 if (timeout < now) 1757 if (timeout < now)
1741 { 1758 {
1742 // timeout occured, take action 1759 // timeout occurred, take action
1743 } 1760 }
1744 else 1761 else
1745 { 1762 {
1746 // callback was invoked, but there was some activity, re-arm 1763 // callback was invoked, but there was some activity, re-arm
1747 // the watcher to fire in last_activity + 60, which is 1764 // the watcher to fire in last_activity + 60, which is
1822 1839
1823=head3 The special problem of time updates 1840=head3 The special problem of time updates
1824 1841
1825Establishing the current time is a costly operation (it usually takes at 1842Establishing the current time is a costly operation (it usually takes at
1826least two system calls): EV therefore updates its idea of the current 1843least two system calls): EV therefore updates its idea of the current
1827time only before and after C<ev_loop> collects new events, which causes a 1844time only before and after C<ev_run> collects new events, which causes a
1828growing difference between C<ev_now ()> and C<ev_time ()> when handling 1845growing difference between C<ev_now ()> and C<ev_time ()> when handling
1829lots of events in one iteration. 1846lots of events in one iteration.
1830 1847
1831The relative timeouts are calculated relative to the C<ev_now ()> 1848The relative timeouts are calculated relative to the C<ev_now ()>
1832time. This is usually the right thing as this timestamp refers to the time 1849time. This is usually the right thing as this timestamp refers to the time
1949 } 1966 }
1950 1967
1951 ev_timer mytimer; 1968 ev_timer mytimer;
1952 ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ 1969 ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1953 ev_timer_again (&mytimer); /* start timer */ 1970 ev_timer_again (&mytimer); /* start timer */
1954 ev_loop (loop, 0); 1971 ev_run (loop, 0);
1955 1972
1956 // and in some piece of code that gets executed on any "activity": 1973 // and in some piece of code that gets executed on any "activity":
1957 // reset the timeout to start ticking again at 10 seconds 1974 // reset the timeout to start ticking again at 10 seconds
1958 ev_timer_again (&mytimer); 1975 ev_timer_again (&mytimer);
1959 1976
1985 2002
1986As with timers, the callback is guaranteed to be invoked only when the 2003As with timers, the callback is guaranteed to be invoked only when the
1987point in time where it is supposed to trigger has passed. If multiple 2004point in time where it is supposed to trigger has passed. If multiple
1988timers become ready during the same loop iteration then the ones with 2005timers become ready during the same loop iteration then the ones with
1989earlier time-out values are invoked before ones with later time-out values 2006earlier 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). 2007(but this is no longer true when a callback calls C<ev_run> recursively).
1991 2008
1992=head3 Watcher-Specific Functions and Data Members 2009=head3 Watcher-Specific Functions and Data Members
1993 2010
1994=over 4 2011=over 4
1995 2012
2123Example: Call a callback every hour, or, more precisely, whenever the 2140Example: Call a callback every hour, or, more precisely, whenever the
2124system time is divisible by 3600. The callback invocation times have 2141system time is divisible by 3600. The callback invocation times have
2125potentially a lot of jitter, but good long-term stability. 2142potentially a lot of jitter, but good long-term stability.
2126 2143
2127 static void 2144 static void
2128 clock_cb (struct ev_loop *loop, ev_io *w, int revents) 2145 clock_cb (struct ev_loop *loop, ev_periodic *w, int revents)
2129 { 2146 {
2130 ... its now a full hour (UTC, or TAI or whatever your clock follows) 2147 ... its now a full hour (UTC, or TAI or whatever your clock follows)
2131 } 2148 }
2132 2149
2133 ev_periodic hourly_tick; 2150 ev_periodic hourly_tick;
2233Example: Try to exit cleanly on SIGINT. 2250Example: Try to exit cleanly on SIGINT.
2234 2251
2235 static void 2252 static void
2236 sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) 2253 sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)
2237 { 2254 {
2238 ev_unloop (loop, EVUNLOOP_ALL); 2255 ev_break (loop, EVBREAK_ALL);
2239 } 2256 }
2240 2257
2241 ev_signal signal_watcher; 2258 ev_signal signal_watcher;
2242 ev_signal_init (&signal_watcher, sigint_cb, SIGINT); 2259 ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
2243 ev_signal_start (loop, &signal_watcher); 2260 ev_signal_start (loop, &signal_watcher);
2629 2646
2630Prepare and check watchers are usually (but not always) used in pairs: 2647Prepare and check watchers are usually (but not always) used in pairs:
2631prepare watchers get invoked before the process blocks and check watchers 2648prepare watchers get invoked before the process blocks and check watchers
2632afterwards. 2649afterwards.
2633 2650
2634You I<must not> call C<ev_loop> or similar functions that enter 2651You I<must not> call C<ev_run> or similar functions that enter
2635the current event loop from either C<ev_prepare> or C<ev_check> 2652the current event loop from either C<ev_prepare> or C<ev_check>
2636watchers. Other loops than the current one are fine, however. The 2653watchers. Other loops than the current one are fine, however. The
2637rationale behind this is that you do not need to check for recursion in 2654rationale behind this is that you do not need to check for recursion in
2638those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, 2655those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,
2639C<ev_check> so if you have one watcher of each kind they will always be 2656C<ev_check> so if you have one watcher of each kind they will always be
2807 2824
2808 if (timeout >= 0) 2825 if (timeout >= 0)
2809 // create/start timer 2826 // create/start timer
2810 2827
2811 // poll 2828 // poll
2812 ev_loop (EV_A_ 0); 2829 ev_run (EV_A_ 0);
2813 2830
2814 // stop timer again 2831 // stop timer again
2815 if (timeout >= 0) 2832 if (timeout >= 0)
2816 ev_timer_stop (EV_A_ &to); 2833 ev_timer_stop (EV_A_ &to);
2817 2834
2895if you do not want that, you need to temporarily stop the embed watcher). 2912if you do not want that, you need to temporarily stop the embed watcher).
2896 2913
2897=item ev_embed_sweep (loop, ev_embed *) 2914=item ev_embed_sweep (loop, ev_embed *)
2898 2915
2899Make a single, non-blocking sweep over the embedded loop. This works 2916Make a single, non-blocking sweep over the embedded loop. This works
2900similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most 2917similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most
2901appropriate way for embedded loops. 2918appropriate way for embedded loops.
2902 2919
2903=item struct ev_loop *other [read-only] 2920=item struct ev_loop *other [read-only]
2904 2921
2905The embedded event loop. 2922The embedded event loop.
2965C<ev_default_fork> cheats and calls it in the wrong process, the fork 2982C<ev_default_fork> cheats and calls it in the wrong process, the fork
2966handlers will be invoked, too, of course. 2983handlers will be invoked, too, of course.
2967 2984
2968=head3 The special problem of life after fork - how is it possible? 2985=head3 The special problem of life after fork - how is it possible?
2969 2986
2970Most uses of C<fork()> consist of forking, then some simple calls to ste 2987Most uses of C<fork()> consist of forking, then some simple calls to set
2971up/change the process environment, followed by a call to C<exec()>. This 2988up/change the process environment, followed by a call to C<exec()>. This
2972sequence should be handled by libev without any problems. 2989sequence should be handled by libev without any problems.
2973 2990
2974This changes when the application actually wants to do event handling 2991This changes when the application actually wants to do event handling
2975in the child, or both parent in child, in effect "continuing" after the 2992in the child, or both parent in child, in effect "continuing" after the
3009believe me. 3026believe me.
3010 3027
3011=back 3028=back
3012 3029
3013 3030
3014=head2 C<ev_async> - how to wake up another event loop 3031=head2 C<ev_async> - how to wake up an event loop
3015 3032
3016In general, you cannot use an C<ev_loop> from multiple threads or other 3033In general, you cannot use an C<ev_run> from multiple threads or other
3017asynchronous sources such as signal handlers (as opposed to multiple event 3034asynchronous sources such as signal handlers (as opposed to multiple event
3018loops - those are of course safe to use in different threads). 3035loops - those are of course safe to use in different threads).
3019 3036
3020Sometimes, however, you need to wake up another event loop you do not 3037Sometimes, however, you need to wake up an event loop you do not control,
3021control, for example because it belongs to another thread. This is what 3038for example because it belongs to another thread. This is what C<ev_async>
3022C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you 3039watchers do: as long as the C<ev_async> watcher is active, you can signal
3023can signal it by calling C<ev_async_send>, which is thread- and signal 3040it by calling C<ev_async_send>, which is thread- and signal safe.
3024safe.
3025 3041
3026This functionality is very similar to C<ev_signal> watchers, as signals, 3042This functionality is very similar to C<ev_signal> watchers, as signals,
3027too, are asynchronous in nature, and signals, too, will be compressed 3043too, are asynchronous in nature, and signals, too, will be compressed
3028(i.e. the number of callback invocations may be less than the number of 3044(i.e. the number of callback invocations may be less than the number of
3029C<ev_async_sent> calls). 3045C<ev_async_sent> calls).
3390Associates a different C<struct ev_loop> with this watcher. You can only 3406Associates a different C<struct ev_loop> with this watcher. You can only
3391do this when the watcher is inactive (and not pending either). 3407do this when the watcher is inactive (and not pending either).
3392 3408
3393=item w->set ([arguments]) 3409=item w->set ([arguments])
3394 3410
3395Basically the same as C<ev_TYPE_set>, with the same arguments. Must be 3411Basically the same as C<ev_TYPE_set>, with the same arguments. Either this
3396called at least once. Unlike the C counterpart, an active watcher gets 3412method or a suitable start method must be called at least once. Unlike the
3397automatically stopped and restarted when reconfiguring it with this 3413C counterpart, an active watcher gets automatically stopped and restarted
3398method. 3414when reconfiguring it with this method.
3399 3415
3400=item w->start () 3416=item w->start ()
3401 3417
3402Starts the watcher. Note that there is no C<loop> argument, as the 3418Starts the watcher. Note that there is no C<loop> argument, as the
3403constructor already stores the event loop. 3419constructor already stores the event loop.
3404 3420
3421=item w->start ([arguments])
3422
3423Instead of calling C<set> and C<start> methods separately, it is often
3424convenient to wrap them in one call. Uses the same type of arguments as
3425the configure C<set> method of the watcher.
3426
3405=item w->stop () 3427=item w->stop ()
3406 3428
3407Stops the watcher if it is active. Again, no C<loop> argument. 3429Stops the watcher if it is active. Again, no C<loop> argument.
3408 3430
3409=item w->again () (C<ev::timer>, C<ev::periodic> only) 3431=item w->again () (C<ev::timer>, C<ev::periodic> only)
3421 3443
3422=back 3444=back
3423 3445
3424=back 3446=back
3425 3447
3426Example: Define a class with an IO and idle watcher, start one of them in 3448Example: Define a class with two I/O and idle watchers, start the I/O
3427the constructor. 3449watchers in the constructor.
3428 3450
3429 class myclass 3451 class myclass
3430 { 3452 {
3431 ev::io io ; void io_cb (ev::io &w, int revents); 3453 ev::io io ; void io_cb (ev::io &w, int revents);
3454 ev::io2 io2 ; void io2_cb (ev::io &w, int revents);
3432 ev::idle idle; void idle_cb (ev::idle &w, int revents); 3455 ev::idle idle; void idle_cb (ev::idle &w, int revents);
3433 3456
3434 myclass (int fd) 3457 myclass (int fd)
3435 { 3458 {
3436 io .set <myclass, &myclass::io_cb > (this); 3459 io .set <myclass, &myclass::io_cb > (this);
3460 io2 .set <myclass, &myclass::io2_cb > (this);
3437 idle.set <myclass, &myclass::idle_cb> (this); 3461 idle.set <myclass, &myclass::idle_cb> (this);
3438 3462
3439 io.start (fd, ev::READ); 3463 io.set (fd, ev::WRITE); // configure the watcher
3464 io.start (); // start it whenever convenient
3465
3466 io2.start (fd, ev::READ); // set + start in one call
3440 } 3467 }
3441 }; 3468 };
3442 3469
3443 3470
3444=head1 OTHER LANGUAGE BINDINGS 3471=head1 OTHER LANGUAGE BINDINGS
3518loop argument"). The C<EV_A> form is used when this is the sole argument, 3545loop argument"). The C<EV_A> form is used when this is the sole argument,
3519C<EV_A_> is used when other arguments are following. Example: 3546C<EV_A_> is used when other arguments are following. Example:
3520 3547
3521 ev_unref (EV_A); 3548 ev_unref (EV_A);
3522 ev_timer_add (EV_A_ watcher); 3549 ev_timer_add (EV_A_ watcher);
3523 ev_loop (EV_A_ 0); 3550 ev_run (EV_A_ 0);
3524 3551
3525It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, 3552It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
3526which is often provided by the following macro. 3553which is often provided by the following macro.
3527 3554
3528=item C<EV_P>, C<EV_P_> 3555=item C<EV_P>, C<EV_P_>
3568 } 3595 }
3569 3596
3570 ev_check check; 3597 ev_check check;
3571 ev_check_init (&check, check_cb); 3598 ev_check_init (&check, check_cb);
3572 ev_check_start (EV_DEFAULT_ &check); 3599 ev_check_start (EV_DEFAULT_ &check);
3573 ev_loop (EV_DEFAULT_ 0); 3600 ev_run (EV_DEFAULT_ 0);
3574 3601
3575=head1 EMBEDDING 3602=head1 EMBEDDING
3576 3603
3577Libev can (and often is) directly embedded into host 3604Libev can (and often is) directly embedded into host
3578applications. Examples of applications that embed it include the Deliantra 3605applications. Examples of applications that embed it include the Deliantra
3669to a compiled library. All other symbols change the ABI, which means all 3696to a compiled library. All other symbols change the ABI, which means all
3670users of libev and the libev code itself must be compiled with compatible 3697users of libev and the libev code itself must be compiled with compatible
3671settings. 3698settings.
3672 3699
3673=over 4 3700=over 4
3701
3702=item EV_COMPAT3 (h)
3703
3704Backwards compatibility is a major concern for libev. This is why this
3705release of libev comes with wrappers for the functions and symbols that
3706have been renamed between libev version 3 and 4.
3707
3708You can disable these wrappers (to test compatibility with future
3709versions) by defining C<EV_COMPAT3> to C<0> when compiling your
3710sources. This has the additional advantage that you can drop the C<struct>
3711from C<struct ev_loop> declarations, as libev will provide an C<ev_loop>
3712typedef in that case.
3713
3714In some future version, the default for C<EV_COMPAT3> will become C<0>,
3715and in some even more future version the compatibility code will be
3716removed completely.
3674 3717
3675=item EV_STANDALONE (h) 3718=item EV_STANDALONE (h)
3676 3719
3677Must always be C<1> if you do not use autoconf configuration, which 3720Must always be C<1> if you do not use autoconf configuration, which
3678keeps libev from including F<config.h>, and it also defines dummy 3721keeps libev from including F<config.h>, and it also defines dummy
3885EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, 3928EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE,
3886EV_ASYNC_ENABLE, EV_CHILD_ENABLE. 3929EV_ASYNC_ENABLE, EV_CHILD_ENABLE.
3887 3930
3888If undefined or defined to be C<1> (and the platform supports it), then 3931If undefined or defined to be C<1> (and the platform supports it), then
3889the respective watcher type is supported. If defined to be C<0>, then it 3932the respective watcher type is supported. If defined to be C<0>, then it
3890is not. Disabling watcher types mainly saves codesize. 3933is not. Disabling watcher types mainly saves code size.
3891 3934
3892=item EV_FEATURES 3935=item EV_FEATURES
3893 3936
3894If you need to shave off some kilobytes of code at the expense of some 3937If you need to shave off some kilobytes of code at the expense of some
3895speed (but with the full API), you can define this symbol to request 3938speed (but with the full API), you can define this symbol to request
3915 3958
3916=item C<1> - faster/larger code 3959=item C<1> - faster/larger code
3917 3960
3918Use larger code to speed up some operations. 3961Use larger code to speed up some operations.
3919 3962
3920Currently this is used to override some inlining decisions (enlarging the roughly 3963Currently this is used to override some inlining decisions (enlarging the
392130% code size on amd64. 3964code size by roughly 30% on amd64).
3922 3965
3923When optimising for size, use of compiler flags such as C<-Os> with 3966When optimising for size, use of compiler flags such as C<-Os> with
3924gcc recommended, as well as C<-DNDEBUG>, as libev contains a number of 3967gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of
3925assertions. 3968assertions.
3926 3969
3927=item C<2> - faster/larger data structures 3970=item C<2> - faster/larger data structures
3928 3971
3929Replaces the small 2-heap for timer management by a faster 4-heap, larger 3972Replaces the small 2-heap for timer management by a faster 4-heap, larger
3930hash table sizes and so on. This will usually further increase codesize 3973hash table sizes and so on. This will usually further increase code size
3931and can additionally have an effect on the size of data structures at 3974and can additionally have an effect on the size of data structures at
3932runtime. 3975runtime.
3933 3976
3934=item C<4> - full API configuration 3977=item C<4> - full API configuration
3935 3978
3972I/O watcher then might come out at only 5Kb. 4015I/O watcher then might come out at only 5Kb.
3973 4016
3974=item EV_AVOID_STDIO 4017=item EV_AVOID_STDIO
3975 4018
3976If this is set to C<1> at compiletime, then libev will avoid using stdio 4019If this is set to C<1> at compiletime, then libev will avoid using stdio
3977functions (printf, scanf, perror etc.). This will increase the codesize 4020functions (printf, scanf, perror etc.). This will increase the code size
3978somewhat, but if your program doesn't otherwise depend on stdio and your 4021somewhat, but if your program doesn't otherwise depend on stdio and your
3979libc allows it, this avoids linking in the stdio library which is quite 4022libc allows it, this avoids linking in the stdio library which is quite
3980big. 4023big.
3981 4024
3982Note that error messages might become less precise when this option is 4025Note that error messages might become less precise when this option is
3986 4029
3987The highest supported signal number, +1 (or, the number of 4030The highest supported signal number, +1 (or, the number of
3988signals): Normally, libev tries to deduce the maximum number of signals 4031signals): Normally, libev tries to deduce the maximum number of signals
3989automatically, but sometimes this fails, in which case it can be 4032automatically, but sometimes this fails, in which case it can be
3990specified. Also, using a lower number than detected (C<32> should be 4033specified. Also, using a lower number than detected (C<32> should be
3991good for about any system in existance) can save some memory, as libev 4034good for about any system in existence) can save some memory, as libev
3992statically allocates some 12-24 bytes per signal number. 4035statically allocates some 12-24 bytes per signal number.
3993 4036
3994=item EV_PID_HASHSIZE 4037=item EV_PID_HASHSIZE
3995 4038
3996C<ev_child> watchers use a small hash table to distribute workload by 4039C<ev_child> watchers use a small hash table to distribute workload by
4028The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it 4071The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
4029will be C<0>. 4072will be C<0>.
4030 4073
4031=item EV_VERIFY 4074=item EV_VERIFY
4032 4075
4033Controls how much internal verification (see C<ev_loop_verify ()>) will 4076Controls how much internal verification (see C<ev_verify ()>) will
4034be done: If set to C<0>, no internal verification code will be compiled 4077be done: If set to C<0>, no internal verification code will be compiled
4035in. If set to C<1>, then verification code will be compiled in, but not 4078in. If set to C<1>, then verification code will be compiled in, but not
4036called. If set to C<2>, then the internal verification code will be 4079called. If set to C<2>, then the internal verification code will be
4037called once per loop, which can slow down libev. If set to C<3>, then the 4080called once per loop, which can slow down libev. If set to C<3>, then the
4038verification code will be called very frequently, which will slow down 4081verification code will be called very frequently, which will slow down
4042will be C<0>. 4085will be C<0>.
4043 4086
4044=item EV_COMMON 4087=item EV_COMMON
4045 4088
4046By default, all watchers have a C<void *data> member. By redefining 4089By default, all watchers have a C<void *data> member. By redefining
4047this macro to a something else you can include more and other types of 4090this macro to something else you can include more and other types of
4048members. You have to define it each time you include one of the files, 4091members. You have to define it each time you include one of the files,
4049though, and it must be identical each time. 4092though, and it must be identical each time.
4050 4093
4051For example, the perl EV module uses something like this: 4094For example, the perl EV module uses something like this:
4052 4095
4253 userdata *u = ev_userdata (EV_A); 4296 userdata *u = ev_userdata (EV_A);
4254 pthread_mutex_lock (&u->lock); 4297 pthread_mutex_lock (&u->lock);
4255 } 4298 }
4256 4299
4257The event loop thread first acquires the mutex, and then jumps straight 4300The event loop thread first acquires the mutex, and then jumps straight
4258into C<ev_loop>: 4301into C<ev_run>:
4259 4302
4260 void * 4303 void *
4261 l_run (void *thr_arg) 4304 l_run (void *thr_arg)
4262 { 4305 {
4263 struct ev_loop *loop = (struct ev_loop *)thr_arg; 4306 struct ev_loop *loop = (struct ev_loop *)thr_arg;
4264 4307
4265 l_acquire (EV_A); 4308 l_acquire (EV_A);
4266 pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); 4309 pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
4267 ev_loop (EV_A_ 0); 4310 ev_run (EV_A_ 0);
4268 l_release (EV_A); 4311 l_release (EV_A);
4269 4312
4270 return 0; 4313 return 0;
4271 } 4314 }
4272 4315
4324 4367
4325=head3 COROUTINES 4368=head3 COROUTINES
4326 4369
4327Libev is very accommodating to coroutines ("cooperative threads"): 4370Libev is very accommodating to coroutines ("cooperative threads"):
4328libev fully supports nesting calls to its functions from different 4371libev fully supports nesting calls to its functions from different
4329coroutines (e.g. you can call C<ev_loop> on the same loop from two 4372coroutines (e.g. you can call C<ev_run> on the same loop from two
4330different coroutines, and switch freely between both coroutines running 4373different coroutines, and switch freely between both coroutines running
4331the loop, as long as you don't confuse yourself). The only exception is 4374the loop, as long as you don't confuse yourself). The only exception is
4332that you must not do this from C<ev_periodic> reschedule callbacks. 4375that you must not do this from C<ev_periodic> reschedule callbacks.
4333 4376
4334Care has been taken to ensure that libev does not keep local state inside 4377Care has been taken to ensure that libev does not keep local state inside
4335C<ev_loop>, and other calls do not usually allow for coroutine switches as 4378C<ev_run>, and other calls do not usually allow for coroutine switches as
4336they do not call any callbacks. 4379they do not call any callbacks.
4337 4380
4338=head2 COMPILER WARNINGS 4381=head2 COMPILER WARNINGS
4339 4382
4340Depending on your compiler and compiler settings, you might get no or a 4383Depending on your compiler and compiler settings, you might get no or a
4351maintainable. 4394maintainable.
4352 4395
4353And of course, some compiler warnings are just plain stupid, or simply 4396And of course, some compiler warnings are just plain stupid, or simply
4354wrong (because they don't actually warn about the condition their message 4397wrong (because they don't actually warn about the condition their message
4355seems to warn about). For example, certain older gcc versions had some 4398seems to warn about). For example, certain older gcc versions had some
4356warnings that resulted an extreme number of false positives. These have 4399warnings that resulted in an extreme number of false positives. These have
4357been fixed, but some people still insist on making code warn-free with 4400been fixed, but some people still insist on making code warn-free with
4358such buggy versions. 4401such buggy versions.
4359 4402
4360While libev is written to generate as few warnings as possible, 4403While libev is written to generate as few warnings as possible,
4361"warn-free" code is not a goal, and it is recommended not to build libev 4404"warn-free" code is not a goal, and it is recommended not to build libev
4397I suggest using suppression lists. 4440I suggest using suppression lists.
4398 4441
4399 4442
4400=head1 PORTABILITY NOTES 4443=head1 PORTABILITY NOTES
4401 4444
4445=head2 GNU/LINUX 32 BIT LIMITATIONS
4446
4447GNU/Linux is the only common platform that supports 64 bit file/large file
4448interfaces but I<disables> them by default.
4449
4450That means that libev compiled in the default environment doesn't support
4451files larger than 2GiB or so, which mainly affects C<ev_stat> watchers.
4452
4453Unfortunately, many programs try to work around this GNU/Linux issue
4454by enabling the large file API, which makes them incompatible with the
4455standard libev compiled for their system.
4456
4457Likewise, libev cannot enable the large file API itself as this would
4458suddenly make it incompatible to the default compile time environment,
4459i.e. all programs not using special compile switches.
4460
4461=head2 OS/X AND DARWIN BUGS
4462
4463The whole thing is a bug if you ask me - basically any system interface
4464you touch is broken, whether it is locales, poll, kqueue or even the
4465OpenGL drivers.
4466
4467=head3 C<kqueue> is buggy
4468
4469The kqueue syscall is broken in all known versions - most versions support
4470only sockets, many support pipes.
4471
4472Libev tries to work around this by not using C<kqueue> by default on
4473this rotten platform, but of course you can still ask for it when creating
4474a loop.
4475
4476=head3 C<poll> is buggy
4477
4478Instead of fixing C<kqueue>, Apple replaced their (working) C<poll>
4479implementation by something calling C<kqueue> internally around the 10.5.6
4480release, so now C<kqueue> I<and> C<poll> are broken.
4481
4482Libev tries to work around this by not using C<poll> by default on
4483this rotten platform, but of course you can still ask for it when creating
4484a loop.
4485
4486=head3 C<select> is buggy
4487
4488All that's left is C<select>, and of course Apple found a way to fuck this
4489one up as well: On OS/X, C<select> actively limits the number of file
4490descriptors you can pass in to 1024 - your program suddenly crashes when
4491you use more.
4492
4493There is an undocumented "workaround" for this - defining
4494C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should>
4495work on OS/X.
4496
4497=head2 SOLARIS PROBLEMS AND WORKAROUNDS
4498
4499=head3 C<errno> reentrancy
4500
4501The default compile environment on Solaris is unfortunately so
4502thread-unsafe that you can't even use components/libraries compiled
4503without C<-D_REENTRANT> (as long as they use C<errno>), which, of course,
4504isn't defined by default.
4505
4506If you want to use libev in threaded environments you have to make sure
4507it's compiled with C<_REENTRANT> defined.
4508
4509=head3 Event port backend
4510
4511The scalable event interface for Solaris is called "event ports". Unfortunately,
4512this mechanism is very buggy. If you run into high CPU usage, your program
4513freezes or you get a large number of spurious wakeups, make sure you have
4514all the relevant and latest kernel patches applied. No, I don't know which
4515ones, but there are multiple ones.
4516
4517If you can't get it to work, you can try running the program by setting
4518the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and
4519C<select> backends.
4520
4521=head2 AIX POLL BUG
4522
4523AIX unfortunately has a broken C<poll.h> header. Libev works around
4524this by trying to avoid the poll backend altogether (i.e. it's not even
4525compiled in), which normally isn't a big problem as C<select> works fine
4526with large bitsets, and AIX is dead anyway.
4527
4402=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS 4528=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
4529
4530=head3 General issues
4403 4531
4404Win32 doesn't support any of the standards (e.g. POSIX) that libev 4532Win32 doesn't support any of the standards (e.g. POSIX) that libev
4405requires, and its I/O model is fundamentally incompatible with the POSIX 4533requires, and its I/O model is fundamentally incompatible with the POSIX
4406model. Libev still offers limited functionality on this platform in 4534model. Libev still offers limited functionality on this platform in
4407the form of the C<EVBACKEND_SELECT> backend, and only supports socket 4535the form of the C<EVBACKEND_SELECT> backend, and only supports socket
4408descriptors. This only applies when using Win32 natively, not when using 4536descriptors. This only applies when using Win32 natively, not when using
4409e.g. cygwin. 4537e.g. cygwin. Actually, it only applies to the microsofts own compilers,
4538as every compielr comes with a slightly differently broken/incompatible
4539environment.
4410 4540
4411Lifting these limitations would basically require the full 4541Lifting these limitations would basically require the full
4412re-implementation of the I/O system. If you are into these kinds of 4542re-implementation of the I/O system. If you are into this kind of thing,
4413things, then note that glib does exactly that for you in a very portable 4543then note that glib does exactly that for you in a very portable way (note
4414way (note also that glib is the slowest event library known to man). 4544also that glib is the slowest event library known to man).
4415 4545
4416There is no supported compilation method available on windows except 4546There is no supported compilation method available on windows except
4417embedding it into other applications. 4547embedding it into other applications.
4418 4548
4419Sensible signal handling is officially unsupported by Microsoft - libev 4549Sensible signal handling is officially unsupported by Microsoft - libev
4447you do I<not> compile the F<ev.c> or any other embedded source files!): 4577you do I<not> compile the F<ev.c> or any other embedded source files!):
4448 4578
4449 #include "evwrap.h" 4579 #include "evwrap.h"
4450 #include "ev.c" 4580 #include "ev.c"
4451 4581
4452=over 4
4453
4454=item The winsocket select function 4582=head3 The winsocket C<select> function
4455 4583
4456The winsocket C<select> function doesn't follow POSIX in that it 4584The winsocket C<select> function doesn't follow POSIX in that it
4457requires socket I<handles> and not socket I<file descriptors> (it is 4585requires socket I<handles> and not socket I<file descriptors> (it is
4458also extremely buggy). This makes select very inefficient, and also 4586also extremely buggy). This makes select very inefficient, and also
4459requires a mapping from file descriptors to socket handles (the Microsoft 4587requires a mapping from file descriptors to socket handles (the Microsoft
4468 #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ 4596 #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
4469 4597
4470Note that winsockets handling of fd sets is O(n), so you can easily get a 4598Note that winsockets handling of fd sets is O(n), so you can easily get a
4471complexity in the O(n²) range when using win32. 4599complexity in the O(n²) range when using win32.
4472 4600
4473=item Limited number of file descriptors 4601=head3 Limited number of file descriptors
4474 4602
4475Windows has numerous arbitrary (and low) limits on things. 4603Windows has numerous arbitrary (and low) limits on things.
4476 4604
4477Early versions of winsocket's select only supported waiting for a maximum 4605Early versions of winsocket's select only supported waiting for a maximum
4478of C<64> handles (probably owning to the fact that all windows kernels 4606of C<64> handles (probably owning to the fact that all windows kernels
4493runtime libraries. This might get you to about C<512> or C<2048> sockets 4621runtime libraries. This might get you to about C<512> or C<2048> sockets
4494(depending on windows version and/or the phase of the moon). To get more, 4622(depending on windows version and/or the phase of the moon). To get more,
4495you need to wrap all I/O functions and provide your own fd management, but 4623you need to wrap all I/O functions and provide your own fd management, but
4496the cost of calling select (O(n²)) will likely make this unworkable. 4624the cost of calling select (O(n²)) will likely make this unworkable.
4497 4625
4498=back
4499
4500=head2 PORTABILITY REQUIREMENTS 4626=head2 PORTABILITY REQUIREMENTS
4501 4627
4502In addition to a working ISO-C implementation and of course the 4628In addition to a working ISO-C implementation and of course the
4503backend-specific APIs, libev relies on a few additional extensions: 4629backend-specific APIs, libev relies on a few additional extensions:
4504 4630
4542watchers. 4668watchers.
4543 4669
4544=item C<double> must hold a time value in seconds with enough accuracy 4670=item C<double> must hold a time value in seconds with enough accuracy
4545 4671
4546The type C<double> is used to represent timestamps. It is required to 4672The type C<double> is used to represent timestamps. It is required to
4547have at least 51 bits of mantissa (and 9 bits of exponent), which is good 4673have at least 51 bits of mantissa (and 9 bits of exponent), which is
4548enough for at least into the year 4000. This requirement is fulfilled by 4674good enough for at least into the year 4000 with millisecond accuracy
4675(the design goal for libev). This requirement is overfulfilled by
4549implementations implementing IEEE 754, which is basically all existing 4676implementations using IEEE 754, which is basically all existing ones. With
4550ones. With IEEE 754 doubles, you get microsecond accuracy until at least 4677IEEE 754 doubles, you get microsecond accuracy until at least 2200.
45512200.
4552 4678
4553=back 4679=back
4554 4680
4555If you know of other additional requirements drop me a note. 4681If you know of other additional requirements drop me a note.
4556 4682
4634compatibility, so most programs should still compile. Those might be 4760compatibility, so most programs should still compile. Those might be
4635removed in later versions of libev, so better update early than late. 4761removed in later versions of libev, so better update early than late.
4636 4762
4637=over 4 4763=over 4
4638 4764
4639=item C<ev_loop_count> renamed to C<ev_iteration> 4765=item function/symbol renames
4640 4766
4641=item C<ev_loop_depth> renamed to C<ev_depth> 4767A number of functions and symbols have been renamed:
4642 4768
4643=item C<ev_loop_verify> renamed to C<ev_verify> 4769 ev_loop => ev_run
4770 EVLOOP_NONBLOCK => EVRUN_NOWAIT
4771 EVLOOP_ONESHOT => EVRUN_ONCE
4772
4773 ev_unloop => ev_break
4774 EVUNLOOP_CANCEL => EVBREAK_CANCEL
4775 EVUNLOOP_ONE => EVBREAK_ONE
4776 EVUNLOOP_ALL => EVBREAK_ALL
4777
4778 EV_TIMEOUT => EV_TIMER
4779
4780 ev_loop_count => ev_iteration
4781 ev_loop_depth => ev_depth
4782 ev_loop_verify => ev_verify
4644 4783
4645Most functions working on C<struct ev_loop> objects don't have an 4784Most functions working on C<struct ev_loop> objects don't have an
4646C<ev_loop_> prefix, so it was removed. Note that C<ev_loop_fork> is 4785C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and
4786associated constants have been renamed to not collide with the C<struct
4787ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme
4788as all other watcher types. Note that C<ev_loop_fork> is still called
4647still called C<ev_loop_fork> because it would otherwise clash with the 4789C<ev_loop_fork> because it would otherwise clash with the C<ev_fork>
4648C<ev_fork> typedef. 4790typedef.
4649 4791
4650=item C<EV_TIMEOUT> renamed to C<EV_TIMER> in C<revents> 4792=item C<EV_COMPAT3> backwards compatibility mechanism
4651 4793
4652This is a simple rename - all other watcher types use their name 4794The backward compatibility mechanism can be controlled by
4653as revents flag, and now C<ev_timer> does, too. 4795C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING>
4654 4796section.
4655Both C<EV_TIMER> and C<EV_TIMEOUT> symbols were present in 3.x versions
4656and continue to be present for the forseeable future, so this is mostly a
4657documentation change.
4658 4797
4659=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES> 4798=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>
4660 4799
4661The preprocessor symbol C<EV_MINIMAL> has been replaced by a different 4800The preprocessor symbol C<EV_MINIMAL> has been replaced by a different
4662mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile 4801mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile

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