… | |
… | |
62 | |
62 | |
63 | // unloop was called, so exit |
63 | // unloop was called, so exit |
64 | return 0; |
64 | return 0; |
65 | } |
65 | } |
66 | |
66 | |
67 | =head1 DESCRIPTION |
67 | =head1 ABOUT THIS DOCUMENT |
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68 | |
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69 | This document documents the libev software package. |
68 | |
70 | |
69 | The newest version of this document is also available as an html-formatted |
71 | The newest version of this document is also available as an html-formatted |
70 | web page you might find easier to navigate when reading it for the first |
72 | web page you might find easier to navigate when reading it for the first |
71 | time: L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>. |
73 | time: L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>. |
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74 | |
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75 | While this document tries to be as complete as possible in documenting |
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76 | libev, its usage and the rationale behind its design, it is not a tutorial |
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77 | on event-based programming, nor will it introduce event-based programming |
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78 | with libev. |
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79 | |
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80 | Familarity with event based programming techniques in general is assumed |
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81 | throughout this document. |
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82 | |
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83 | =head1 ABOUT LIBEV |
72 | |
84 | |
73 | Libev is an event loop: you register interest in certain events (such as a |
85 | Libev is an event loop: you register interest in certain events (such as a |
74 | file descriptor being readable or a timeout occurring), and it will manage |
86 | file descriptor being readable or a timeout occurring), and it will manage |
75 | these event sources and provide your program with events. |
87 | these event sources and provide your program with events. |
76 | |
88 | |
… | |
… | |
86 | =head2 FEATURES |
98 | =head2 FEATURES |
87 | |
99 | |
88 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
100 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
89 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
101 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
90 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
102 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
91 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
103 | (for C<ev_stat>), Linux eventfd/signalfd (for faster and cleaner |
92 | with customised rescheduling (C<ev_periodic>), synchronous signals |
104 | inter-thread wakeup (C<ev_async>)/signal handling (C<ev_signal>)) relative |
93 | (C<ev_signal>), process status change events (C<ev_child>), and event |
105 | timers (C<ev_timer>), absolute timers with customised rescheduling |
94 | watchers dealing with the event loop mechanism itself (C<ev_idle>, |
106 | (C<ev_periodic>), synchronous signals (C<ev_signal>), process status |
95 | C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as |
107 | change events (C<ev_child>), and event watchers dealing with the event |
96 | file watchers (C<ev_stat>) and even limited support for fork events |
108 | loop mechanism itself (C<ev_idle>, C<ev_embed>, C<ev_prepare> and |
97 | (C<ev_fork>). |
109 | C<ev_check> watchers) as well as file watchers (C<ev_stat>) and even |
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110 | limited support for fork events (C<ev_fork>). |
98 | |
111 | |
99 | It also is quite fast (see this |
112 | It also is quite fast (see this |
100 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
113 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
101 | for example). |
114 | for example). |
102 | |
115 | |
… | |
… | |
105 | Libev is very configurable. In this manual the default (and most common) |
118 | Libev is very configurable. In this manual the default (and most common) |
106 | configuration will be described, which supports multiple event loops. For |
119 | configuration will be described, which supports multiple event loops. For |
107 | more info about various configuration options please have a look at |
120 | more info about various configuration options please have a look at |
108 | B<EMBED> section in this manual. If libev was configured without support |
121 | B<EMBED> section in this manual. If libev was configured without support |
109 | for multiple event loops, then all functions taking an initial argument of |
122 | for multiple event loops, then all functions taking an initial argument of |
110 | name C<loop> (which is always of type C<ev_loop *>) will not have |
123 | name C<loop> (which is always of type C<struct ev_loop *>) will not have |
111 | this argument. |
124 | this argument. |
112 | |
125 | |
113 | =head2 TIME REPRESENTATION |
126 | =head2 TIME REPRESENTATION |
114 | |
127 | |
115 | Libev represents time as a single floating point number, representing the |
128 | Libev represents time as a single floating point number, representing |
116 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
129 | the (fractional) number of seconds since the (POSIX) epoch (somewhere |
117 | the beginning of 1970, details are complicated, don't ask). This type is |
130 | near the beginning of 1970, details are complicated, don't ask). This |
118 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
131 | type is called C<ev_tstamp>, which is what you should use too. It usually |
119 | to the C<double> type in C, and when you need to do any calculations on |
132 | aliases to the C<double> type in C. When you need to do any calculations |
120 | it, you should treat it as some floating point value. Unlike the name |
133 | on it, you should treat it as some floating point value. Unlike the name |
121 | component C<stamp> might indicate, it is also used for time differences |
134 | component C<stamp> might indicate, it is also used for time differences |
122 | throughout libev. |
135 | throughout libev. |
123 | |
136 | |
124 | =head1 ERROR HANDLING |
137 | =head1 ERROR HANDLING |
125 | |
138 | |
… | |
… | |
350 | flag. |
363 | flag. |
351 | |
364 | |
352 | This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS> |
365 | This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS> |
353 | environment variable. |
366 | environment variable. |
354 | |
367 | |
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368 | =item C<EVFLAG_NOINOTIFY> |
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369 | |
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370 | When this flag is specified, then libev will not attempt to use the |
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371 | I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and |
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372 | testing, this flag can be useful to conserve inotify file descriptors, as |
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373 | otherwise each loop using C<ev_stat> watchers consumes one inotify handle. |
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374 | |
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375 | =item C<EVFLAG_SIGNALFD> |
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376 | |
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377 | When this flag is specified, then libev will attempt to use the |
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378 | I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This API |
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379 | delivers signals synchronously, which makes it both faster and might make |
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380 | it possible to get the queued signal data. It can also simplify signal |
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381 | handling with threads, as long as you properly block signals in your |
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382 | threads that are not interested in handling them. |
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383 | |
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384 | Signalfd will not be used by default as this changes your signal mask, and |
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385 | there are a lot of shoddy libraries and programs (glib's threadpool for |
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386 | example) that can't properly initialise their signal masks. |
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387 | |
355 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
388 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
356 | |
389 | |
357 | This is your standard select(2) backend. Not I<completely> standard, as |
390 | This is your standard select(2) backend. Not I<completely> standard, as |
358 | libev tries to roll its own fd_set with no limits on the number of fds, |
391 | libev tries to roll its own fd_set with no limits on the number of fds, |
359 | but if that fails, expect a fairly low limit on the number of fds when |
392 | but if that fails, expect a fairly low limit on the number of fds when |
… | |
… | |
382 | |
415 | |
383 | This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and |
416 | This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and |
384 | C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. |
417 | C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. |
385 | |
418 | |
386 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
419 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
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420 | |
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421 | Use the linux-specific epoll(7) interface (for both pre- and post-2.6.9 |
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422 | kernels). |
387 | |
423 | |
388 | For few fds, this backend is a bit little slower than poll and select, |
424 | For few fds, this backend is a bit little slower than poll and select, |
389 | but it scales phenomenally better. While poll and select usually scale |
425 | but it scales phenomenally better. While poll and select usually scale |
390 | like O(total_fds) where n is the total number of fds (or the highest fd), |
426 | like O(total_fds) where n is the total number of fds (or the highest fd), |
391 | epoll scales either O(1) or O(active_fds). |
427 | epoll scales either O(1) or O(active_fds). |
… | |
… | |
506 | |
542 | |
507 | It is definitely not recommended to use this flag. |
543 | It is definitely not recommended to use this flag. |
508 | |
544 | |
509 | =back |
545 | =back |
510 | |
546 | |
511 | If one or more of these are or'ed into the flags value, then only these |
547 | If one or more of the backend flags are or'ed into the flags value, |
512 | backends will be tried (in the reverse order as listed here). If none are |
548 | then only these backends will be tried (in the reverse order as listed |
513 | specified, all backends in C<ev_recommended_backends ()> will be tried. |
549 | here). If none are specified, all backends in C<ev_recommended_backends |
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550 | ()> will be tried. |
514 | |
551 | |
515 | Example: This is the most typical usage. |
552 | Example: This is the most typical usage. |
516 | |
553 | |
517 | if (!ev_default_loop (0)) |
554 | if (!ev_default_loop (0)) |
518 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
555 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
… | |
… | |
561 | as signal and child watchers) would need to be stopped manually. |
598 | as signal and child watchers) would need to be stopped manually. |
562 | |
599 | |
563 | In general it is not advisable to call this function except in the |
600 | In general it is not advisable to call this function except in the |
564 | rare occasion where you really need to free e.g. the signal handling |
601 | rare occasion where you really need to free e.g. the signal handling |
565 | pipe fds. If you need dynamically allocated loops it is better to use |
602 | pipe fds. If you need dynamically allocated loops it is better to use |
566 | C<ev_loop_new> and C<ev_loop_destroy>). |
603 | C<ev_loop_new> and C<ev_loop_destroy>. |
567 | |
604 | |
568 | =item ev_loop_destroy (loop) |
605 | =item ev_loop_destroy (loop) |
569 | |
606 | |
570 | Like C<ev_default_destroy>, but destroys an event loop created by an |
607 | Like C<ev_default_destroy>, but destroys an event loop created by an |
571 | earlier call to C<ev_loop_new>. |
608 | earlier call to C<ev_loop_new>. |
… | |
… | |
609 | |
646 | |
610 | This value can sometimes be useful as a generation counter of sorts (it |
647 | This value can sometimes be useful as a generation counter of sorts (it |
611 | "ticks" the number of loop iterations), as it roughly corresponds with |
648 | "ticks" the number of loop iterations), as it roughly corresponds with |
612 | C<ev_prepare> and C<ev_check> calls. |
649 | C<ev_prepare> and C<ev_check> calls. |
613 | |
650 | |
|
|
651 | =item unsigned int ev_loop_depth (loop) |
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|
652 | |
|
|
653 | Returns the number of times C<ev_loop> was entered minus the number of |
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|
654 | times C<ev_loop> was exited, in other words, the recursion depth. |
|
|
655 | |
|
|
656 | Outside C<ev_loop>, this number is zero. In a callback, this number is |
|
|
657 | C<1>, unless C<ev_loop> was invoked recursively (or from another thread), |
|
|
658 | in which case it is higher. |
|
|
659 | |
|
|
660 | Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread |
|
|
661 | etc.), doesn't count as exit. |
|
|
662 | |
614 | =item unsigned int ev_backend (loop) |
663 | =item unsigned int ev_backend (loop) |
615 | |
664 | |
616 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
665 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
617 | use. |
666 | use. |
618 | |
667 | |
… | |
… | |
632 | |
681 | |
633 | This function is rarely useful, but when some event callback runs for a |
682 | This function is rarely useful, but when some event callback runs for a |
634 | very long time without entering the event loop, updating libev's idea of |
683 | very long time without entering the event loop, updating libev's idea of |
635 | the current time is a good idea. |
684 | the current time is a good idea. |
636 | |
685 | |
637 | See also "The special problem of time updates" in the C<ev_timer> section. |
686 | See also L<The special problem of time updates> in the C<ev_timer> section. |
638 | |
687 | |
639 | =item ev_suspend (loop) |
688 | =item ev_suspend (loop) |
640 | |
689 | |
641 | =item ev_resume (loop) |
690 | =item ev_resume (loop) |
642 | |
691 | |
… | |
… | |
663 | event loop time (see C<ev_now_update>). |
712 | event loop time (see C<ev_now_update>). |
664 | |
713 | |
665 | =item ev_loop (loop, int flags) |
714 | =item ev_loop (loop, int flags) |
666 | |
715 | |
667 | Finally, this is it, the event handler. This function usually is called |
716 | Finally, this is it, the event handler. This function usually is called |
668 | after you initialised all your watchers and you want to start handling |
717 | after you have initialised all your watchers and you want to start |
669 | events. |
718 | handling events. |
670 | |
719 | |
671 | If the flags argument is specified as C<0>, it will not return until |
720 | If the flags argument is specified as C<0>, it will not return until |
672 | either no event watchers are active anymore or C<ev_unloop> was called. |
721 | either no event watchers are active anymore or C<ev_unloop> was called. |
673 | |
722 | |
674 | Please note that an explicit C<ev_unloop> is usually better than |
723 | Please note that an explicit C<ev_unloop> is usually better than |
… | |
… | |
748 | |
797 | |
749 | Ref/unref can be used to add or remove a reference count on the event |
798 | Ref/unref can be used to add or remove a reference count on the event |
750 | loop: Every watcher keeps one reference, and as long as the reference |
799 | loop: Every watcher keeps one reference, and as long as the reference |
751 | count is nonzero, C<ev_loop> will not return on its own. |
800 | count is nonzero, C<ev_loop> will not return on its own. |
752 | |
801 | |
753 | If you have a watcher you never unregister that should not keep C<ev_loop> |
802 | This is useful when you have a watcher that you never intend to |
754 | from returning, call ev_unref() after starting, and ev_ref() before |
803 | unregister, but that nevertheless should not keep C<ev_loop> from |
|
|
804 | returning. In such a case, call C<ev_unref> after starting, and C<ev_ref> |
755 | stopping it. |
805 | before stopping it. |
756 | |
806 | |
757 | As an example, libev itself uses this for its internal signal pipe: It |
807 | As an example, libev itself uses this for its internal signal pipe: It |
758 | is not visible to the libev user and should not keep C<ev_loop> from |
808 | is not visible to the libev user and should not keep C<ev_loop> from |
759 | exiting if no event watchers registered by it are active. It is also an |
809 | exiting if no event watchers registered by it are active. It is also an |
760 | excellent way to do this for generic recurring timers or from within |
810 | excellent way to do this for generic recurring timers or from within |
… | |
… | |
799 | |
849 | |
800 | By setting a higher I<io collect interval> you allow libev to spend more |
850 | By setting a higher I<io collect interval> you allow libev to spend more |
801 | time collecting I/O events, so you can handle more events per iteration, |
851 | time collecting I/O events, so you can handle more events per iteration, |
802 | at the cost of increasing latency. Timeouts (both C<ev_periodic> and |
852 | at the cost of increasing latency. Timeouts (both C<ev_periodic> and |
803 | C<ev_timer>) will be not affected. Setting this to a non-null value will |
853 | C<ev_timer>) will be not affected. Setting this to a non-null value will |
804 | introduce an additional C<ev_sleep ()> call into most loop iterations. |
854 | introduce an additional C<ev_sleep ()> call into most loop iterations. The |
|
|
855 | sleep time ensures that libev will not poll for I/O events more often then |
|
|
856 | once per this interval, on average. |
805 | |
857 | |
806 | Likewise, by setting a higher I<timeout collect interval> you allow libev |
858 | Likewise, by setting a higher I<timeout collect interval> you allow libev |
807 | to spend more time collecting timeouts, at the expense of increased |
859 | to spend more time collecting timeouts, at the expense of increased |
808 | latency/jitter/inexactness (the watcher callback will be called |
860 | latency/jitter/inexactness (the watcher callback will be called |
809 | later). C<ev_io> watchers will not be affected. Setting this to a non-null |
861 | later). C<ev_io> watchers will not be affected. Setting this to a non-null |
… | |
… | |
811 | |
863 | |
812 | Many (busy) programs can usually benefit by setting the I/O collect |
864 | Many (busy) programs can usually benefit by setting the I/O collect |
813 | interval to a value near C<0.1> or so, which is often enough for |
865 | interval to a value near C<0.1> or so, which is often enough for |
814 | interactive servers (of course not for games), likewise for timeouts. It |
866 | interactive servers (of course not for games), likewise for timeouts. It |
815 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
867 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
816 | as this approaches the timing granularity of most systems. |
868 | as this approaches the timing granularity of most systems. Note that if |
|
|
869 | you do transactions with the outside world and you can't increase the |
|
|
870 | parallelity, then this setting will limit your transaction rate (if you |
|
|
871 | need to poll once per transaction and the I/O collect interval is 0.01, |
|
|
872 | then you can't do more than 100 transations per second). |
817 | |
873 | |
818 | Setting the I<timeout collect interval> can improve the opportunity for |
874 | Setting the I<timeout collect interval> can improve the opportunity for |
819 | saving power, as the program will "bundle" timer callback invocations that |
875 | saving power, as the program will "bundle" timer callback invocations that |
820 | are "near" in time together, by delaying some, thus reducing the number of |
876 | are "near" in time together, by delaying some, thus reducing the number of |
821 | times the process sleeps and wakes up again. Another useful technique to |
877 | times the process sleeps and wakes up again. Another useful technique to |
822 | reduce iterations/wake-ups is to use C<ev_periodic> watchers and make sure |
878 | reduce iterations/wake-ups is to use C<ev_periodic> watchers and make sure |
823 | they fire on, say, one-second boundaries only. |
879 | they fire on, say, one-second boundaries only. |
|
|
880 | |
|
|
881 | Example: we only need 0.1s timeout granularity, and we wish not to poll |
|
|
882 | more often than 100 times per second: |
|
|
883 | |
|
|
884 | ev_set_timeout_collect_interval (EV_DEFAULT_UC_ 0.1); |
|
|
885 | ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
|
|
886 | |
|
|
887 | =item ev_invoke_pending (loop) |
|
|
888 | |
|
|
889 | This call will simply invoke all pending watchers while resetting their |
|
|
890 | pending state. Normally, C<ev_loop> does this automatically when required, |
|
|
891 | but when overriding the invoke callback this call comes handy. |
|
|
892 | |
|
|
893 | =item int ev_pending_count (loop) |
|
|
894 | |
|
|
895 | Returns the number of pending watchers - zero indicates that no watchers |
|
|
896 | are pending. |
|
|
897 | |
|
|
898 | =item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P)) |
|
|
899 | |
|
|
900 | This overrides the invoke pending functionality of the loop: Instead of |
|
|
901 | invoking all pending watchers when there are any, C<ev_loop> will call |
|
|
902 | this callback instead. This is useful, for example, when you want to |
|
|
903 | invoke the actual watchers inside another context (another thread etc.). |
|
|
904 | |
|
|
905 | If you want to reset the callback, use C<ev_invoke_pending> as new |
|
|
906 | callback. |
|
|
907 | |
|
|
908 | =item ev_set_loop_release_cb (loop, void (*release)(EV_P), void (*acquire)(EV_P)) |
|
|
909 | |
|
|
910 | Sometimes you want to share the same loop between multiple threads. This |
|
|
911 | can be done relatively simply by putting mutex_lock/unlock calls around |
|
|
912 | each call to a libev function. |
|
|
913 | |
|
|
914 | However, C<ev_loop> can run an indefinite time, so it is not feasible to |
|
|
915 | wait for it to return. One way around this is to wake up the loop via |
|
|
916 | C<ev_unloop> and C<av_async_send>, another way is to set these I<release> |
|
|
917 | and I<acquire> callbacks on the loop. |
|
|
918 | |
|
|
919 | When set, then C<release> will be called just before the thread is |
|
|
920 | suspended waiting for new events, and C<acquire> is called just |
|
|
921 | afterwards. |
|
|
922 | |
|
|
923 | Ideally, C<release> will just call your mutex_unlock function, and |
|
|
924 | C<acquire> will just call the mutex_lock function again. |
|
|
925 | |
|
|
926 | While event loop modifications are allowed between invocations of |
|
|
927 | C<release> and C<acquire> (that's their only purpose after all), no |
|
|
928 | modifications done will affect the event loop, i.e. adding watchers will |
|
|
929 | have no effect on the set of file descriptors being watched, or the time |
|
|
930 | waited. Use an C<ev_async> watcher to wake up C<ev_loop> when you want it |
|
|
931 | to take note of any changes you made. |
|
|
932 | |
|
|
933 | In theory, threads executing C<ev_loop> will be async-cancel safe between |
|
|
934 | invocations of C<release> and C<acquire>. |
|
|
935 | |
|
|
936 | See also the locking example in the C<THREADS> section later in this |
|
|
937 | document. |
|
|
938 | |
|
|
939 | =item ev_set_userdata (loop, void *data) |
|
|
940 | |
|
|
941 | =item ev_userdata (loop) |
|
|
942 | |
|
|
943 | Set and retrieve a single C<void *> associated with a loop. When |
|
|
944 | C<ev_set_userdata> has never been called, then C<ev_userdata> returns |
|
|
945 | C<0.> |
|
|
946 | |
|
|
947 | These two functions can be used to associate arbitrary data with a loop, |
|
|
948 | and are intended solely for the C<invoke_pending_cb>, C<release> and |
|
|
949 | C<acquire> callbacks described above, but of course can be (ab-)used for |
|
|
950 | any other purpose as well. |
824 | |
951 | |
825 | =item ev_loop_verify (loop) |
952 | =item ev_loop_verify (loop) |
826 | |
953 | |
827 | This function only does something when C<EV_VERIFY> support has been |
954 | This function only does something when C<EV_VERIFY> support has been |
828 | compiled in, which is the default for non-minimal builds. It tries to go |
955 | compiled in, which is the default for non-minimal builds. It tries to go |
… | |
… | |
1005 | |
1132 | |
1006 | ev_io w; |
1133 | ev_io w; |
1007 | ev_init (&w, my_cb); |
1134 | ev_init (&w, my_cb); |
1008 | ev_io_set (&w, STDIN_FILENO, EV_READ); |
1135 | ev_io_set (&w, STDIN_FILENO, EV_READ); |
1009 | |
1136 | |
1010 | =item C<ev_TYPE_set> (ev_TYPE *, [args]) |
1137 | =item C<ev_TYPE_set> (ev_TYPE *watcher, [args]) |
1011 | |
1138 | |
1012 | This macro initialises the type-specific parts of a watcher. You need to |
1139 | This macro initialises the type-specific parts of a watcher. You need to |
1013 | call C<ev_init> at least once before you call this macro, but you can |
1140 | call C<ev_init> at least once before you call this macro, but you can |
1014 | call C<ev_TYPE_set> any number of times. You must not, however, call this |
1141 | call C<ev_TYPE_set> any number of times. You must not, however, call this |
1015 | macro on a watcher that is active (it can be pending, however, which is a |
1142 | macro on a watcher that is active (it can be pending, however, which is a |
… | |
… | |
1028 | |
1155 | |
1029 | Example: Initialise and set an C<ev_io> watcher in one step. |
1156 | Example: Initialise and set an C<ev_io> watcher in one step. |
1030 | |
1157 | |
1031 | ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1158 | ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1032 | |
1159 | |
1033 | =item C<ev_TYPE_start> (loop *, ev_TYPE *watcher) |
1160 | =item C<ev_TYPE_start> (loop, ev_TYPE *watcher) |
1034 | |
1161 | |
1035 | Starts (activates) the given watcher. Only active watchers will receive |
1162 | Starts (activates) the given watcher. Only active watchers will receive |
1036 | events. If the watcher is already active nothing will happen. |
1163 | events. If the watcher is already active nothing will happen. |
1037 | |
1164 | |
1038 | Example: Start the C<ev_io> watcher that is being abused as example in this |
1165 | Example: Start the C<ev_io> watcher that is being abused as example in this |
1039 | whole section. |
1166 | whole section. |
1040 | |
1167 | |
1041 | ev_io_start (EV_DEFAULT_UC, &w); |
1168 | ev_io_start (EV_DEFAULT_UC, &w); |
1042 | |
1169 | |
1043 | =item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher) |
1170 | =item C<ev_TYPE_stop> (loop, ev_TYPE *watcher) |
1044 | |
1171 | |
1045 | Stops the given watcher if active, and clears the pending status (whether |
1172 | Stops the given watcher if active, and clears the pending status (whether |
1046 | the watcher was active or not). |
1173 | the watcher was active or not). |
1047 | |
1174 | |
1048 | It is possible that stopped watchers are pending - for example, |
1175 | It is possible that stopped watchers are pending - for example, |
… | |
… | |
1073 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1200 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1074 | |
1201 | |
1075 | Change the callback. You can change the callback at virtually any time |
1202 | Change the callback. You can change the callback at virtually any time |
1076 | (modulo threads). |
1203 | (modulo threads). |
1077 | |
1204 | |
1078 | =item ev_set_priority (ev_TYPE *watcher, priority) |
1205 | =item ev_set_priority (ev_TYPE *watcher, int priority) |
1079 | |
1206 | |
1080 | =item int ev_priority (ev_TYPE *watcher) |
1207 | =item int ev_priority (ev_TYPE *watcher) |
1081 | |
1208 | |
1082 | Set and query the priority of the watcher. The priority is a small |
1209 | Set and query the priority of the watcher. The priority is a small |
1083 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
1210 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
1084 | (default: C<-2>). Pending watchers with higher priority will be invoked |
1211 | (default: C<-2>). Pending watchers with higher priority will be invoked |
1085 | before watchers with lower priority, but priority will not keep watchers |
1212 | before watchers with lower priority, but priority will not keep watchers |
1086 | from being executed (except for C<ev_idle> watchers). |
1213 | from being executed (except for C<ev_idle> watchers). |
1087 | |
1214 | |
1088 | This means that priorities are I<only> used for ordering callback |
|
|
1089 | invocation after new events have been received. This is useful, for |
|
|
1090 | example, to reduce latency after idling, or more often, to bind two |
|
|
1091 | watchers on the same event and make sure one is called first. |
|
|
1092 | |
|
|
1093 | If you need to suppress invocation when higher priority events are pending |
1215 | If you need to suppress invocation when higher priority events are pending |
1094 | you need to look at C<ev_idle> watchers, which provide this functionality. |
1216 | you need to look at C<ev_idle> watchers, which provide this functionality. |
1095 | |
1217 | |
1096 | You I<must not> change the priority of a watcher as long as it is active or |
1218 | You I<must not> change the priority of a watcher as long as it is active or |
1097 | pending. |
1219 | pending. |
1098 | |
|
|
1099 | The default priority used by watchers when no priority has been set is |
|
|
1100 | always C<0>, which is supposed to not be too high and not be too low :). |
|
|
1101 | |
1220 | |
1102 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
1221 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
1103 | fine, as long as you do not mind that the priority value you query might |
1222 | fine, as long as you do not mind that the priority value you query might |
1104 | or might not have been clamped to the valid range. |
1223 | or might not have been clamped to the valid range. |
|
|
1224 | |
|
|
1225 | The default priority used by watchers when no priority has been set is |
|
|
1226 | always C<0>, which is supposed to not be too high and not be too low :). |
|
|
1227 | |
|
|
1228 | See L<WATCHER PRIORITY MODELS>, below, for a more thorough treatment of |
|
|
1229 | priorities. |
1105 | |
1230 | |
1106 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
1231 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
1107 | |
1232 | |
1108 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
1233 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
1109 | C<loop> nor C<revents> need to be valid as long as the watcher callback |
1234 | C<loop> nor C<revents> need to be valid as long as the watcher callback |
… | |
… | |
1116 | returns its C<revents> bitset (as if its callback was invoked). If the |
1241 | returns its C<revents> bitset (as if its callback was invoked). If the |
1117 | watcher isn't pending it does nothing and returns C<0>. |
1242 | watcher isn't pending it does nothing and returns C<0>. |
1118 | |
1243 | |
1119 | Sometimes it can be useful to "poll" a watcher instead of waiting for its |
1244 | Sometimes it can be useful to "poll" a watcher instead of waiting for its |
1120 | callback to be invoked, which can be accomplished with this function. |
1245 | callback to be invoked, which can be accomplished with this function. |
|
|
1246 | |
|
|
1247 | =item ev_feed_event (loop, ev_TYPE *watcher, int revents) |
|
|
1248 | |
|
|
1249 | Feeds the given event set into the event loop, as if the specified event |
|
|
1250 | had happened for the specified watcher (which must be a pointer to an |
|
|
1251 | initialised but not necessarily started event watcher). Obviously you must |
|
|
1252 | not free the watcher as long as it has pending events. |
|
|
1253 | |
|
|
1254 | Stopping the watcher, letting libev invoke it, or calling |
|
|
1255 | C<ev_clear_pending> will clear the pending event, even if the watcher was |
|
|
1256 | not started in the first place. |
|
|
1257 | |
|
|
1258 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
|
|
1259 | functions that do not need a watcher. |
1121 | |
1260 | |
1122 | =back |
1261 | =back |
1123 | |
1262 | |
1124 | |
1263 | |
1125 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
1264 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
… | |
… | |
1174 | #include <stddef.h> |
1313 | #include <stddef.h> |
1175 | |
1314 | |
1176 | static void |
1315 | static void |
1177 | t1_cb (EV_P_ ev_timer *w, int revents) |
1316 | t1_cb (EV_P_ ev_timer *w, int revents) |
1178 | { |
1317 | { |
1179 | struct my_biggy big = (struct my_biggy * |
1318 | struct my_biggy big = (struct my_biggy *) |
1180 | (((char *)w) - offsetof (struct my_biggy, t1)); |
1319 | (((char *)w) - offsetof (struct my_biggy, t1)); |
1181 | } |
1320 | } |
1182 | |
1321 | |
1183 | static void |
1322 | static void |
1184 | t2_cb (EV_P_ ev_timer *w, int revents) |
1323 | t2_cb (EV_P_ ev_timer *w, int revents) |
1185 | { |
1324 | { |
1186 | struct my_biggy big = (struct my_biggy * |
1325 | struct my_biggy big = (struct my_biggy *) |
1187 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1326 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1188 | } |
1327 | } |
|
|
1328 | |
|
|
1329 | =head2 WATCHER PRIORITY MODELS |
|
|
1330 | |
|
|
1331 | Many event loops support I<watcher priorities>, which are usually small |
|
|
1332 | integers that influence the ordering of event callback invocation |
|
|
1333 | between watchers in some way, all else being equal. |
|
|
1334 | |
|
|
1335 | In libev, Watcher priorities can be set using C<ev_set_priority>. See its |
|
|
1336 | description for the more technical details such as the actual priority |
|
|
1337 | range. |
|
|
1338 | |
|
|
1339 | There are two common ways how these these priorities are being interpreted |
|
|
1340 | by event loops: |
|
|
1341 | |
|
|
1342 | In the more common lock-out model, higher priorities "lock out" invocation |
|
|
1343 | of lower priority watchers, which means as long as higher priority |
|
|
1344 | watchers receive events, lower priority watchers are not being invoked. |
|
|
1345 | |
|
|
1346 | The less common only-for-ordering model uses priorities solely to order |
|
|
1347 | callback invocation within a single event loop iteration: Higher priority |
|
|
1348 | watchers are invoked before lower priority ones, but they all get invoked |
|
|
1349 | before polling for new events. |
|
|
1350 | |
|
|
1351 | Libev uses the second (only-for-ordering) model for all its watchers |
|
|
1352 | except for idle watchers (which use the lock-out model). |
|
|
1353 | |
|
|
1354 | The rationale behind this is that implementing the lock-out model for |
|
|
1355 | watchers is not well supported by most kernel interfaces, and most event |
|
|
1356 | libraries will just poll for the same events again and again as long as |
|
|
1357 | their callbacks have not been executed, which is very inefficient in the |
|
|
1358 | common case of one high-priority watcher locking out a mass of lower |
|
|
1359 | priority ones. |
|
|
1360 | |
|
|
1361 | Static (ordering) priorities are most useful when you have two or more |
|
|
1362 | watchers handling the same resource: a typical usage example is having an |
|
|
1363 | C<ev_io> watcher to receive data, and an associated C<ev_timer> to handle |
|
|
1364 | timeouts. Under load, data might be received while the program handles |
|
|
1365 | other jobs, but since timers normally get invoked first, the timeout |
|
|
1366 | handler will be executed before checking for data. In that case, giving |
|
|
1367 | the timer a lower priority than the I/O watcher ensures that I/O will be |
|
|
1368 | handled first even under adverse conditions (which is usually, but not |
|
|
1369 | always, what you want). |
|
|
1370 | |
|
|
1371 | Since idle watchers use the "lock-out" model, meaning that idle watchers |
|
|
1372 | will only be executed when no same or higher priority watchers have |
|
|
1373 | received events, they can be used to implement the "lock-out" model when |
|
|
1374 | required. |
|
|
1375 | |
|
|
1376 | For example, to emulate how many other event libraries handle priorities, |
|
|
1377 | you can associate an C<ev_idle> watcher to each such watcher, and in |
|
|
1378 | the normal watcher callback, you just start the idle watcher. The real |
|
|
1379 | processing is done in the idle watcher callback. This causes libev to |
|
|
1380 | continously poll and process kernel event data for the watcher, but when |
|
|
1381 | the lock-out case is known to be rare (which in turn is rare :), this is |
|
|
1382 | workable. |
|
|
1383 | |
|
|
1384 | Usually, however, the lock-out model implemented that way will perform |
|
|
1385 | miserably under the type of load it was designed to handle. In that case, |
|
|
1386 | it might be preferable to stop the real watcher before starting the |
|
|
1387 | idle watcher, so the kernel will not have to process the event in case |
|
|
1388 | the actual processing will be delayed for considerable time. |
|
|
1389 | |
|
|
1390 | Here is an example of an I/O watcher that should run at a strictly lower |
|
|
1391 | priority than the default, and which should only process data when no |
|
|
1392 | other events are pending: |
|
|
1393 | |
|
|
1394 | ev_idle idle; // actual processing watcher |
|
|
1395 | ev_io io; // actual event watcher |
|
|
1396 | |
|
|
1397 | static void |
|
|
1398 | io_cb (EV_P_ ev_io *w, int revents) |
|
|
1399 | { |
|
|
1400 | // stop the I/O watcher, we received the event, but |
|
|
1401 | // are not yet ready to handle it. |
|
|
1402 | ev_io_stop (EV_A_ w); |
|
|
1403 | |
|
|
1404 | // start the idle watcher to ahndle the actual event. |
|
|
1405 | // it will not be executed as long as other watchers |
|
|
1406 | // with the default priority are receiving events. |
|
|
1407 | ev_idle_start (EV_A_ &idle); |
|
|
1408 | } |
|
|
1409 | |
|
|
1410 | static void |
|
|
1411 | idle_cb (EV_P_ ev_idle *w, int revents) |
|
|
1412 | { |
|
|
1413 | // actual processing |
|
|
1414 | read (STDIN_FILENO, ...); |
|
|
1415 | |
|
|
1416 | // have to start the I/O watcher again, as |
|
|
1417 | // we have handled the event |
|
|
1418 | ev_io_start (EV_P_ &io); |
|
|
1419 | } |
|
|
1420 | |
|
|
1421 | // initialisation |
|
|
1422 | ev_idle_init (&idle, idle_cb); |
|
|
1423 | ev_io_init (&io, io_cb, STDIN_FILENO, EV_READ); |
|
|
1424 | ev_io_start (EV_DEFAULT_ &io); |
|
|
1425 | |
|
|
1426 | In the "real" world, it might also be beneficial to start a timer, so that |
|
|
1427 | low-priority connections can not be locked out forever under load. This |
|
|
1428 | enables your program to keep a lower latency for important connections |
|
|
1429 | during short periods of high load, while not completely locking out less |
|
|
1430 | important ones. |
1189 | |
1431 | |
1190 | |
1432 | |
1191 | =head1 WATCHER TYPES |
1433 | =head1 WATCHER TYPES |
1192 | |
1434 | |
1193 | This section describes each watcher in detail, but will not repeat |
1435 | This section describes each watcher in detail, but will not repeat |
… | |
… | |
1219 | descriptors to non-blocking mode is also usually a good idea (but not |
1461 | descriptors to non-blocking mode is also usually a good idea (but not |
1220 | required if you know what you are doing). |
1462 | required if you know what you are doing). |
1221 | |
1463 | |
1222 | If you cannot use non-blocking mode, then force the use of a |
1464 | If you cannot use non-blocking mode, then force the use of a |
1223 | known-to-be-good backend (at the time of this writing, this includes only |
1465 | known-to-be-good backend (at the time of this writing, this includes only |
1224 | C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). |
1466 | C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file |
|
|
1467 | descriptors for which non-blocking operation makes no sense (such as |
|
|
1468 | files) - libev doesn't guarentee any specific behaviour in that case. |
1225 | |
1469 | |
1226 | Another thing you have to watch out for is that it is quite easy to |
1470 | Another thing you have to watch out for is that it is quite easy to |
1227 | receive "spurious" readiness notifications, that is your callback might |
1471 | receive "spurious" readiness notifications, that is your callback might |
1228 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1472 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1229 | because there is no data. Not only are some backends known to create a |
1473 | because there is no data. Not only are some backends known to create a |
… | |
… | |
1294 | |
1538 | |
1295 | So when you encounter spurious, unexplained daemon exits, make sure you |
1539 | So when you encounter spurious, unexplained daemon exits, make sure you |
1296 | ignore SIGPIPE (and maybe make sure you log the exit status of your daemon |
1540 | ignore SIGPIPE (and maybe make sure you log the exit status of your daemon |
1297 | somewhere, as that would have given you a big clue). |
1541 | somewhere, as that would have given you a big clue). |
1298 | |
1542 | |
|
|
1543 | =head3 The special problem of accept()ing when you can't |
|
|
1544 | |
|
|
1545 | Many implementations of the POSIX C<accept> function (for example, |
|
|
1546 | found in port-2004 Linux) have the peculiar behaviour of not removing a |
|
|
1547 | connection from the pending queue in all error cases. |
|
|
1548 | |
|
|
1549 | For example, larger servers often run out of file descriptors (because |
|
|
1550 | of resource limits), causing C<accept> to fail with C<ENFILE> but not |
|
|
1551 | rejecting the connection, leading to libev signalling readiness on |
|
|
1552 | the next iteration again (the connection still exists after all), and |
|
|
1553 | typically causing the program to loop at 100% CPU usage. |
|
|
1554 | |
|
|
1555 | Unfortunately, the set of errors that cause this issue differs between |
|
|
1556 | operating systems, there is usually little the app can do to remedy the |
|
|
1557 | situation, and no known thread-safe method of removing the connection to |
|
|
1558 | cope with overload is known (to me). |
|
|
1559 | |
|
|
1560 | One of the easiest ways to handle this situation is to just ignore it |
|
|
1561 | - when the program encounters an overload, it will just loop until the |
|
|
1562 | situation is over. While this is a form of busy waiting, no OS offers an |
|
|
1563 | event-based way to handle this situation, so it's the best one can do. |
|
|
1564 | |
|
|
1565 | A better way to handle the situation is to log any errors other than |
|
|
1566 | C<EAGAIN> and C<EWOULDBLOCK>, making sure not to flood the log with such |
|
|
1567 | messages, and continue as usual, which at least gives the user an idea of |
|
|
1568 | what could be wrong ("raise the ulimit!"). For extra points one could stop |
|
|
1569 | the C<ev_io> watcher on the listening fd "for a while", which reduces CPU |
|
|
1570 | usage. |
|
|
1571 | |
|
|
1572 | If your program is single-threaded, then you could also keep a dummy file |
|
|
1573 | descriptor for overload situations (e.g. by opening F</dev/null>), and |
|
|
1574 | when you run into C<ENFILE> or C<EMFILE>, close it, run C<accept>, |
|
|
1575 | close that fd, and create a new dummy fd. This will gracefully refuse |
|
|
1576 | clients under typical overload conditions. |
|
|
1577 | |
|
|
1578 | The last way to handle it is to simply log the error and C<exit>, as |
|
|
1579 | is often done with C<malloc> failures, but this results in an easy |
|
|
1580 | opportunity for a DoS attack. |
1299 | |
1581 | |
1300 | =head3 Watcher-Specific Functions |
1582 | =head3 Watcher-Specific Functions |
1301 | |
1583 | |
1302 | =over 4 |
1584 | =over 4 |
1303 | |
1585 | |
… | |
… | |
1350 | year, it will still time out after (roughly) one hour. "Roughly" because |
1632 | year, it will still time out after (roughly) one hour. "Roughly" because |
1351 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1633 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1352 | monotonic clock option helps a lot here). |
1634 | monotonic clock option helps a lot here). |
1353 | |
1635 | |
1354 | The callback is guaranteed to be invoked only I<after> its timeout has |
1636 | The callback is guaranteed to be invoked only I<after> its timeout has |
1355 | passed. If multiple timers become ready during the same loop iteration |
1637 | passed (not I<at>, so on systems with very low-resolution clocks this |
1356 | then the ones with earlier time-out values are invoked before ones with |
1638 | might introduce a small delay). If multiple timers become ready during the |
1357 | later time-out values (but this is no longer true when a callback calls |
1639 | same loop iteration then the ones with earlier time-out values are invoked |
1358 | C<ev_loop> recursively). |
1640 | before ones of the same priority with later time-out values (but this is |
|
|
1641 | no longer true when a callback calls C<ev_loop> recursively). |
1359 | |
1642 | |
1360 | =head3 Be smart about timeouts |
1643 | =head3 Be smart about timeouts |
1361 | |
1644 | |
1362 | Many real-world problems involve some kind of timeout, usually for error |
1645 | Many real-world problems involve some kind of timeout, usually for error |
1363 | recovery. A typical example is an HTTP request - if the other side hangs, |
1646 | recovery. A typical example is an HTTP request - if the other side hangs, |
… | |
… | |
1407 | C<after> argument to C<ev_timer_set>, and only ever use the C<repeat> |
1690 | C<after> argument to C<ev_timer_set>, and only ever use the C<repeat> |
1408 | member and C<ev_timer_again>. |
1691 | member and C<ev_timer_again>. |
1409 | |
1692 | |
1410 | At start: |
1693 | At start: |
1411 | |
1694 | |
1412 | ev_timer_init (timer, callback); |
1695 | ev_init (timer, callback); |
1413 | timer->repeat = 60.; |
1696 | timer->repeat = 60.; |
1414 | ev_timer_again (loop, timer); |
1697 | ev_timer_again (loop, timer); |
1415 | |
1698 | |
1416 | Each time there is some activity: |
1699 | Each time there is some activity: |
1417 | |
1700 | |
… | |
… | |
1479 | |
1762 | |
1480 | To start the timer, simply initialise the watcher and set C<last_activity> |
1763 | To start the timer, simply initialise the watcher and set C<last_activity> |
1481 | to the current time (meaning we just have some activity :), then call the |
1764 | to the current time (meaning we just have some activity :), then call the |
1482 | callback, which will "do the right thing" and start the timer: |
1765 | callback, which will "do the right thing" and start the timer: |
1483 | |
1766 | |
1484 | ev_timer_init (timer, callback); |
1767 | ev_init (timer, callback); |
1485 | last_activity = ev_now (loop); |
1768 | last_activity = ev_now (loop); |
1486 | callback (loop, timer, EV_TIMEOUT); |
1769 | callback (loop, timer, EV_TIMEOUT); |
1487 | |
1770 | |
1488 | And when there is some activity, simply store the current time in |
1771 | And when there is some activity, simply store the current time in |
1489 | C<last_activity>, no libev calls at all: |
1772 | C<last_activity>, no libev calls at all: |
… | |
… | |
1550 | |
1833 | |
1551 | If the event loop is suspended for a long time, you can also force an |
1834 | If the event loop is suspended for a long time, you can also force an |
1552 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
1835 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
1553 | ()>. |
1836 | ()>. |
1554 | |
1837 | |
|
|
1838 | =head3 The special problems of suspended animation |
|
|
1839 | |
|
|
1840 | When you leave the server world it is quite customary to hit machines that |
|
|
1841 | can suspend/hibernate - what happens to the clocks during such a suspend? |
|
|
1842 | |
|
|
1843 | Some quick tests made with a Linux 2.6.28 indicate that a suspend freezes |
|
|
1844 | all processes, while the clocks (C<times>, C<CLOCK_MONOTONIC>) continue |
|
|
1845 | to run until the system is suspended, but they will not advance while the |
|
|
1846 | system is suspended. That means, on resume, it will be as if the program |
|
|
1847 | was frozen for a few seconds, but the suspend time will not be counted |
|
|
1848 | towards C<ev_timer> when a monotonic clock source is used. The real time |
|
|
1849 | clock advanced as expected, but if it is used as sole clocksource, then a |
|
|
1850 | long suspend would be detected as a time jump by libev, and timers would |
|
|
1851 | be adjusted accordingly. |
|
|
1852 | |
|
|
1853 | I would not be surprised to see different behaviour in different between |
|
|
1854 | operating systems, OS versions or even different hardware. |
|
|
1855 | |
|
|
1856 | The other form of suspend (job control, or sending a SIGSTOP) will see a |
|
|
1857 | time jump in the monotonic clocks and the realtime clock. If the program |
|
|
1858 | is suspended for a very long time, and monotonic clock sources are in use, |
|
|
1859 | then you can expect C<ev_timer>s to expire as the full suspension time |
|
|
1860 | will be counted towards the timers. When no monotonic clock source is in |
|
|
1861 | use, then libev will again assume a timejump and adjust accordingly. |
|
|
1862 | |
|
|
1863 | It might be beneficial for this latter case to call C<ev_suspend> |
|
|
1864 | and C<ev_resume> in code that handles C<SIGTSTP>, to at least get |
|
|
1865 | deterministic behaviour in this case (you can do nothing against |
|
|
1866 | C<SIGSTOP>). |
|
|
1867 | |
1555 | =head3 Watcher-Specific Functions and Data Members |
1868 | =head3 Watcher-Specific Functions and Data Members |
1556 | |
1869 | |
1557 | =over 4 |
1870 | =over 4 |
1558 | |
1871 | |
1559 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
1872 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
… | |
… | |
1582 | If the timer is started but non-repeating, stop it (as if it timed out). |
1895 | If the timer is started but non-repeating, stop it (as if it timed out). |
1583 | |
1896 | |
1584 | If the timer is repeating, either start it if necessary (with the |
1897 | If the timer is repeating, either start it if necessary (with the |
1585 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1898 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1586 | |
1899 | |
1587 | This sounds a bit complicated, see "Be smart about timeouts", above, for a |
1900 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
1588 | usage example. |
1901 | usage example. |
|
|
1902 | |
|
|
1903 | =item ev_tstamp ev_timer_remaining (loop, ev_timer *) |
|
|
1904 | |
|
|
1905 | Returns the remaining time until a timer fires. If the timer is active, |
|
|
1906 | then this time is relative to the current event loop time, otherwise it's |
|
|
1907 | the timeout value currently configured. |
|
|
1908 | |
|
|
1909 | That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns |
|
|
1910 | C<5>. When the timer is started and one second passes, C<ev_timer_remaining> |
|
|
1911 | will return C<4>. When the timer expires and is restarted, it will return |
|
|
1912 | roughly C<7> (likely slightly less as callback invocation takes some time, |
|
|
1913 | too), and so on. |
1589 | |
1914 | |
1590 | =item ev_tstamp repeat [read-write] |
1915 | =item ev_tstamp repeat [read-write] |
1591 | |
1916 | |
1592 | The current C<repeat> value. Will be used each time the watcher times out |
1917 | The current C<repeat> value. Will be used each time the watcher times out |
1593 | or C<ev_timer_again> is called, and determines the next timeout (if any), |
1918 | or C<ev_timer_again> is called, and determines the next timeout (if any), |
… | |
… | |
1829 | Signal watchers will trigger an event when the process receives a specific |
2154 | Signal watchers will trigger an event when the process receives a specific |
1830 | signal one or more times. Even though signals are very asynchronous, libev |
2155 | signal one or more times. Even though signals are very asynchronous, libev |
1831 | will try it's best to deliver signals synchronously, i.e. as part of the |
2156 | will try it's best to deliver signals synchronously, i.e. as part of the |
1832 | normal event processing, like any other event. |
2157 | normal event processing, like any other event. |
1833 | |
2158 | |
1834 | If you want signals asynchronously, just use C<sigaction> as you would |
2159 | If you want signals to be delivered truly asynchronously, just use |
1835 | do without libev and forget about sharing the signal. You can even use |
2160 | C<sigaction> as you would do without libev and forget about sharing |
1836 | C<ev_async> from a signal handler to synchronously wake up an event loop. |
2161 | the signal. You can even use C<ev_async> from a signal handler to |
|
|
2162 | synchronously wake up an event loop. |
1837 | |
2163 | |
1838 | You can configure as many watchers as you like per signal. Only when the |
2164 | You can configure as many watchers as you like for the same signal, but |
|
|
2165 | only within the same loop, i.e. you can watch for C<SIGINT> in your |
|
|
2166 | default loop and for C<SIGIO> in another loop, but you cannot watch for |
|
|
2167 | C<SIGINT> in both the default loop and another loop at the same time. At |
|
|
2168 | the moment, C<SIGCHLD> is permanently tied to the default loop. |
|
|
2169 | |
1839 | first watcher gets started will libev actually register a signal handler |
2170 | When the first watcher gets started will libev actually register something |
1840 | with the kernel (thus it coexists with your own signal handlers as long as |
2171 | with the kernel (thus it coexists with your own signal handlers as long as |
1841 | you don't register any with libev for the same signal). Similarly, when |
2172 | you don't register any with libev for the same signal). |
1842 | the last signal watcher for a signal is stopped, libev will reset the |
|
|
1843 | signal handler to SIG_DFL (regardless of what it was set to before). |
|
|
1844 | |
2173 | |
1845 | If possible and supported, libev will install its handlers with |
2174 | If possible and supported, libev will install its handlers with |
1846 | C<SA_RESTART> behaviour enabled, so system calls should not be unduly |
2175 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
1847 | interrupted. If you have a problem with system calls getting interrupted by |
2176 | not be unduly interrupted. If you have a problem with system calls getting |
1848 | signals you can block all signals in an C<ev_check> watcher and unblock |
2177 | interrupted by signals you can block all signals in an C<ev_check> watcher |
1849 | them in an C<ev_prepare> watcher. |
2178 | and unblock them in an C<ev_prepare> watcher. |
|
|
2179 | |
|
|
2180 | =head3 The special problem of inheritance over fork/execve/pthread_create |
|
|
2181 | |
|
|
2182 | Both the signal mask (C<sigprocmask>) and the signal disposition |
|
|
2183 | (C<sigaction>) are unspecified after starting a signal watcher (and after |
|
|
2184 | stopping it again), that is, libev might or might not block the signal, |
|
|
2185 | and might or might not set or restore the installed signal handler. |
|
|
2186 | |
|
|
2187 | While this does not matter for the signal disposition (libev never |
|
|
2188 | sets signals to C<SIG_IGN>, so handlers will be reset to C<SIG_DFL> on |
|
|
2189 | C<execve>), this matters for the signal mask: many programs do not expect |
|
|
2190 | certain signals to be blocked. |
|
|
2191 | |
|
|
2192 | This means that before calling C<exec> (from the child) you should reset |
|
|
2193 | the signal mask to whatever "default" you expect (all clear is a good |
|
|
2194 | choice usually). |
|
|
2195 | |
|
|
2196 | The simplest way to ensure that the signal mask is reset in the child is |
|
|
2197 | to install a fork handler with C<pthread_atfork> that resets it. That will |
|
|
2198 | catch fork calls done by libraries (such as the libc) as well. |
|
|
2199 | |
|
|
2200 | In current versions of libev, the signal will not be blocked indefinitely |
|
|
2201 | unless you use the C<signalfd> API (C<EV_SIGNALFD>). While this reduces |
|
|
2202 | the window of opportunity for problems, it will not go away, as libev |
|
|
2203 | I<has> to modify the signal mask, at least temporarily. |
|
|
2204 | |
|
|
2205 | So I can't stress this enough: I<If you do not reset your signal mask when |
|
|
2206 | you expect it to be empty, you have a race condition in your code>. This |
|
|
2207 | is not a libev-specific thing, this is true for most event libraries. |
1850 | |
2208 | |
1851 | =head3 Watcher-Specific Functions and Data Members |
2209 | =head3 Watcher-Specific Functions and Data Members |
1852 | |
2210 | |
1853 | =over 4 |
2211 | =over 4 |
1854 | |
2212 | |
… | |
… | |
1886 | some child status changes (most typically when a child of yours dies or |
2244 | some child status changes (most typically when a child of yours dies or |
1887 | exits). It is permissible to install a child watcher I<after> the child |
2245 | exits). It is permissible to install a child watcher I<after> the child |
1888 | has been forked (which implies it might have already exited), as long |
2246 | has been forked (which implies it might have already exited), as long |
1889 | as the event loop isn't entered (or is continued from a watcher), i.e., |
2247 | as the event loop isn't entered (or is continued from a watcher), i.e., |
1890 | forking and then immediately registering a watcher for the child is fine, |
2248 | forking and then immediately registering a watcher for the child is fine, |
1891 | but forking and registering a watcher a few event loop iterations later is |
2249 | but forking and registering a watcher a few event loop iterations later or |
1892 | not. |
2250 | in the next callback invocation is not. |
1893 | |
2251 | |
1894 | Only the default event loop is capable of handling signals, and therefore |
2252 | Only the default event loop is capable of handling signals, and therefore |
1895 | you can only register child watchers in the default event loop. |
2253 | you can only register child watchers in the default event loop. |
1896 | |
2254 | |
|
|
2255 | Due to some design glitches inside libev, child watchers will always be |
|
|
2256 | handled at maximum priority (their priority is set to C<EV_MAXPRI> by |
|
|
2257 | libev) |
|
|
2258 | |
1897 | =head3 Process Interaction |
2259 | =head3 Process Interaction |
1898 | |
2260 | |
1899 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
2261 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
1900 | initialised. This is necessary to guarantee proper behaviour even if |
2262 | initialised. This is necessary to guarantee proper behaviour even if the |
1901 | the first child watcher is started after the child exits. The occurrence |
2263 | first child watcher is started after the child exits. The occurrence |
1902 | of C<SIGCHLD> is recorded asynchronously, but child reaping is done |
2264 | of C<SIGCHLD> is recorded asynchronously, but child reaping is done |
1903 | synchronously as part of the event loop processing. Libev always reaps all |
2265 | synchronously as part of the event loop processing. Libev always reaps all |
1904 | children, even ones not watched. |
2266 | children, even ones not watched. |
1905 | |
2267 | |
1906 | =head3 Overriding the Built-In Processing |
2268 | =head3 Overriding the Built-In Processing |
… | |
… | |
1916 | =head3 Stopping the Child Watcher |
2278 | =head3 Stopping the Child Watcher |
1917 | |
2279 | |
1918 | Currently, the child watcher never gets stopped, even when the |
2280 | Currently, the child watcher never gets stopped, even when the |
1919 | child terminates, so normally one needs to stop the watcher in the |
2281 | child terminates, so normally one needs to stop the watcher in the |
1920 | callback. Future versions of libev might stop the watcher automatically |
2282 | callback. Future versions of libev might stop the watcher automatically |
1921 | when a child exit is detected. |
2283 | when a child exit is detected (calling C<ev_child_stop> twice is not a |
|
|
2284 | problem). |
1922 | |
2285 | |
1923 | =head3 Watcher-Specific Functions and Data Members |
2286 | =head3 Watcher-Specific Functions and Data Members |
1924 | |
2287 | |
1925 | =over 4 |
2288 | =over 4 |
1926 | |
2289 | |
… | |
… | |
2252 | // no longer anything immediate to do. |
2615 | // no longer anything immediate to do. |
2253 | } |
2616 | } |
2254 | |
2617 | |
2255 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
2618 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
2256 | ev_idle_init (idle_watcher, idle_cb); |
2619 | ev_idle_init (idle_watcher, idle_cb); |
2257 | ev_idle_start (loop, idle_cb); |
2620 | ev_idle_start (loop, idle_watcher); |
2258 | |
2621 | |
2259 | |
2622 | |
2260 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
2623 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
2261 | |
2624 | |
2262 | Prepare and check watchers are usually (but not always) used in pairs: |
2625 | Prepare and check watchers are usually (but not always) used in pairs: |
… | |
… | |
2355 | struct pollfd fds [nfd]; |
2718 | struct pollfd fds [nfd]; |
2356 | // actual code will need to loop here and realloc etc. |
2719 | // actual code will need to loop here and realloc etc. |
2357 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
2720 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
2358 | |
2721 | |
2359 | /* the callback is illegal, but won't be called as we stop during check */ |
2722 | /* the callback is illegal, but won't be called as we stop during check */ |
2360 | ev_timer_init (&tw, 0, timeout * 1e-3); |
2723 | ev_timer_init (&tw, 0, timeout * 1e-3, 0.); |
2361 | ev_timer_start (loop, &tw); |
2724 | ev_timer_start (loop, &tw); |
2362 | |
2725 | |
2363 | // create one ev_io per pollfd |
2726 | // create one ev_io per pollfd |
2364 | for (int i = 0; i < nfd; ++i) |
2727 | for (int i = 0; i < nfd; ++i) |
2365 | { |
2728 | { |
… | |
… | |
2595 | event loop blocks next and before C<ev_check> watchers are being called, |
2958 | event loop blocks next and before C<ev_check> watchers are being called, |
2596 | and only in the child after the fork. If whoever good citizen calling |
2959 | and only in the child after the fork. If whoever good citizen calling |
2597 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
2960 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
2598 | handlers will be invoked, too, of course. |
2961 | handlers will be invoked, too, of course. |
2599 | |
2962 | |
|
|
2963 | =head3 The special problem of life after fork - how is it possible? |
|
|
2964 | |
|
|
2965 | Most uses of C<fork()> consist of forking, then some simple calls to ste |
|
|
2966 | up/change the process environment, followed by a call to C<exec()>. This |
|
|
2967 | sequence should be handled by libev without any problems. |
|
|
2968 | |
|
|
2969 | This changes when the application actually wants to do event handling |
|
|
2970 | in the child, or both parent in child, in effect "continuing" after the |
|
|
2971 | fork. |
|
|
2972 | |
|
|
2973 | The default mode of operation (for libev, with application help to detect |
|
|
2974 | forks) is to duplicate all the state in the child, as would be expected |
|
|
2975 | when I<either> the parent I<or> the child process continues. |
|
|
2976 | |
|
|
2977 | When both processes want to continue using libev, then this is usually the |
|
|
2978 | wrong result. In that case, usually one process (typically the parent) is |
|
|
2979 | supposed to continue with all watchers in place as before, while the other |
|
|
2980 | process typically wants to start fresh, i.e. without any active watchers. |
|
|
2981 | |
|
|
2982 | The cleanest and most efficient way to achieve that with libev is to |
|
|
2983 | simply create a new event loop, which of course will be "empty", and |
|
|
2984 | use that for new watchers. This has the advantage of not touching more |
|
|
2985 | memory than necessary, and thus avoiding the copy-on-write, and the |
|
|
2986 | disadvantage of having to use multiple event loops (which do not support |
|
|
2987 | signal watchers). |
|
|
2988 | |
|
|
2989 | When this is not possible, or you want to use the default loop for |
|
|
2990 | other reasons, then in the process that wants to start "fresh", call |
|
|
2991 | C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying |
|
|
2992 | the default loop will "orphan" (not stop) all registered watchers, so you |
|
|
2993 | have to be careful not to execute code that modifies those watchers. Note |
|
|
2994 | also that in that case, you have to re-register any signal watchers. |
|
|
2995 | |
2600 | =head3 Watcher-Specific Functions and Data Members |
2996 | =head3 Watcher-Specific Functions and Data Members |
2601 | |
2997 | |
2602 | =over 4 |
2998 | =over 4 |
2603 | |
2999 | |
2604 | =item ev_fork_init (ev_signal *, callback) |
3000 | =item ev_fork_init (ev_signal *, callback) |
… | |
… | |
2633 | =head3 Queueing |
3029 | =head3 Queueing |
2634 | |
3030 | |
2635 | C<ev_async> does not support queueing of data in any way. The reason |
3031 | C<ev_async> does not support queueing of data in any way. The reason |
2636 | is that the author does not know of a simple (or any) algorithm for a |
3032 | is that the author does not know of a simple (or any) algorithm for a |
2637 | multiple-writer-single-reader queue that works in all cases and doesn't |
3033 | multiple-writer-single-reader queue that works in all cases and doesn't |
2638 | need elaborate support such as pthreads. |
3034 | need elaborate support such as pthreads or unportable memory access |
|
|
3035 | semantics. |
2639 | |
3036 | |
2640 | That means that if you want to queue data, you have to provide your own |
3037 | That means that if you want to queue data, you have to provide your own |
2641 | queue. But at least I can tell you how to implement locking around your |
3038 | queue. But at least I can tell you how to implement locking around your |
2642 | queue: |
3039 | queue: |
2643 | |
3040 | |
… | |
… | |
2801 | /* doh, nothing entered */; |
3198 | /* doh, nothing entered */; |
2802 | } |
3199 | } |
2803 | |
3200 | |
2804 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3201 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
2805 | |
3202 | |
2806 | =item ev_feed_event (struct ev_loop *, watcher *, int revents) |
|
|
2807 | |
|
|
2808 | Feeds the given event set into the event loop, as if the specified event |
|
|
2809 | had happened for the specified watcher (which must be a pointer to an |
|
|
2810 | initialised but not necessarily started event watcher). |
|
|
2811 | |
|
|
2812 | =item ev_feed_fd_event (struct ev_loop *, int fd, int revents) |
3203 | =item ev_feed_fd_event (loop, int fd, int revents) |
2813 | |
3204 | |
2814 | Feed an event on the given fd, as if a file descriptor backend detected |
3205 | Feed an event on the given fd, as if a file descriptor backend detected |
2815 | the given events it. |
3206 | the given events it. |
2816 | |
3207 | |
2817 | =item ev_feed_signal_event (struct ev_loop *loop, int signum) |
3208 | =item ev_feed_signal_event (loop, int signum) |
2818 | |
3209 | |
2819 | Feed an event as if the given signal occurred (C<loop> must be the default |
3210 | Feed an event as if the given signal occurred (C<loop> must be the default |
2820 | loop!). |
3211 | loop!). |
2821 | |
3212 | |
2822 | =back |
3213 | =back |
… | |
… | |
2902 | |
3293 | |
2903 | =over 4 |
3294 | =over 4 |
2904 | |
3295 | |
2905 | =item ev::TYPE::TYPE () |
3296 | =item ev::TYPE::TYPE () |
2906 | |
3297 | |
2907 | =item ev::TYPE::TYPE (struct ev_loop *) |
3298 | =item ev::TYPE::TYPE (loop) |
2908 | |
3299 | |
2909 | =item ev::TYPE::~TYPE |
3300 | =item ev::TYPE::~TYPE |
2910 | |
3301 | |
2911 | The constructor (optionally) takes an event loop to associate the watcher |
3302 | The constructor (optionally) takes an event loop to associate the watcher |
2912 | with. If it is omitted, it will use C<EV_DEFAULT>. |
3303 | with. If it is omitted, it will use C<EV_DEFAULT>. |
… | |
… | |
2989 | Example: Use a plain function as callback. |
3380 | Example: Use a plain function as callback. |
2990 | |
3381 | |
2991 | static void io_cb (ev::io &w, int revents) { } |
3382 | static void io_cb (ev::io &w, int revents) { } |
2992 | iow.set <io_cb> (); |
3383 | iow.set <io_cb> (); |
2993 | |
3384 | |
2994 | =item w->set (struct ev_loop *) |
3385 | =item w->set (loop) |
2995 | |
3386 | |
2996 | Associates a different C<struct ev_loop> with this watcher. You can only |
3387 | Associates a different C<struct ev_loop> with this watcher. You can only |
2997 | do this when the watcher is inactive (and not pending either). |
3388 | do this when the watcher is inactive (and not pending either). |
2998 | |
3389 | |
2999 | =item w->set ([arguments]) |
3390 | =item w->set ([arguments]) |
… | |
… | |
3096 | =item Ocaml |
3487 | =item Ocaml |
3097 | |
3488 | |
3098 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3489 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3099 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
3490 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
3100 | |
3491 | |
|
|
3492 | =item Lua |
|
|
3493 | |
|
|
3494 | Brian Maher has written a partial interface to libev for lua (at the |
|
|
3495 | time of this writing, only C<ev_io> and C<ev_timer>), to be found at |
|
|
3496 | L<http://github.com/brimworks/lua-ev>. |
|
|
3497 | |
3101 | =back |
3498 | =back |
3102 | |
3499 | |
3103 | |
3500 | |
3104 | =head1 MACRO MAGIC |
3501 | =head1 MACRO MAGIC |
3105 | |
3502 | |
… | |
… | |
3258 | libev.m4 |
3655 | libev.m4 |
3259 | |
3656 | |
3260 | =head2 PREPROCESSOR SYMBOLS/MACROS |
3657 | =head2 PREPROCESSOR SYMBOLS/MACROS |
3261 | |
3658 | |
3262 | Libev can be configured via a variety of preprocessor symbols you have to |
3659 | Libev can be configured via a variety of preprocessor symbols you have to |
3263 | define before including any of its files. The default in the absence of |
3660 | define before including (or compiling) any of its files. The default in |
3264 | autoconf is documented for every option. |
3661 | the absence of autoconf is documented for every option. |
|
|
3662 | |
|
|
3663 | Symbols marked with "(h)" do not change the ABI, and can have different |
|
|
3664 | values when compiling libev vs. including F<ev.h>, so it is permissible |
|
|
3665 | to redefine them before including F<ev.h> without breakign compatibility |
|
|
3666 | to a compiled library. All other symbols change the ABI, which means all |
|
|
3667 | users of libev and the libev code itself must be compiled with compatible |
|
|
3668 | settings. |
3265 | |
3669 | |
3266 | =over 4 |
3670 | =over 4 |
3267 | |
3671 | |
3268 | =item EV_STANDALONE |
3672 | =item EV_STANDALONE (h) |
3269 | |
3673 | |
3270 | Must always be C<1> if you do not use autoconf configuration, which |
3674 | Must always be C<1> if you do not use autoconf configuration, which |
3271 | keeps libev from including F<config.h>, and it also defines dummy |
3675 | keeps libev from including F<config.h>, and it also defines dummy |
3272 | implementations for some libevent functions (such as logging, which is not |
3676 | implementations for some libevent functions (such as logging, which is not |
3273 | supported). It will also not define any of the structs usually found in |
3677 | supported). It will also not define any of the structs usually found in |
3274 | F<event.h> that are not directly supported by the libev core alone. |
3678 | F<event.h> that are not directly supported by the libev core alone. |
3275 | |
3679 | |
3276 | In stanbdalone mode, libev will still try to automatically deduce the |
3680 | In standalone mode, libev will still try to automatically deduce the |
3277 | configuration, but has to be more conservative. |
3681 | configuration, but has to be more conservative. |
3278 | |
3682 | |
3279 | =item EV_USE_MONOTONIC |
3683 | =item EV_USE_MONOTONIC |
3280 | |
3684 | |
3281 | If defined to be C<1>, libev will try to detect the availability of the |
3685 | If defined to be C<1>, libev will try to detect the availability of the |
… | |
… | |
3346 | be used is the winsock select). This means that it will call |
3750 | be used is the winsock select). This means that it will call |
3347 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
3751 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
3348 | it is assumed that all these functions actually work on fds, even |
3752 | it is assumed that all these functions actually work on fds, even |
3349 | on win32. Should not be defined on non-win32 platforms. |
3753 | on win32. Should not be defined on non-win32 platforms. |
3350 | |
3754 | |
3351 | =item EV_FD_TO_WIN32_HANDLE |
3755 | =item EV_FD_TO_WIN32_HANDLE(fd) |
3352 | |
3756 | |
3353 | If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map |
3757 | If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map |
3354 | file descriptors to socket handles. When not defining this symbol (the |
3758 | file descriptors to socket handles. When not defining this symbol (the |
3355 | default), then libev will call C<_get_osfhandle>, which is usually |
3759 | default), then libev will call C<_get_osfhandle>, which is usually |
3356 | correct. In some cases, programs use their own file descriptor management, |
3760 | correct. In some cases, programs use their own file descriptor management, |
3357 | in which case they can provide this function to map fds to socket handles. |
3761 | in which case they can provide this function to map fds to socket handles. |
|
|
3762 | |
|
|
3763 | =item EV_WIN32_HANDLE_TO_FD(handle) |
|
|
3764 | |
|
|
3765 | If C<EV_SELECT_IS_WINSOCKET> then libev maps handles to file descriptors |
|
|
3766 | using the standard C<_open_osfhandle> function. For programs implementing |
|
|
3767 | their own fd to handle mapping, overwriting this function makes it easier |
|
|
3768 | to do so. This can be done by defining this macro to an appropriate value. |
|
|
3769 | |
|
|
3770 | =item EV_WIN32_CLOSE_FD(fd) |
|
|
3771 | |
|
|
3772 | If programs implement their own fd to handle mapping on win32, then this |
|
|
3773 | macro can be used to override the C<close> function, useful to unregister |
|
|
3774 | file descriptors again. Note that the replacement function has to close |
|
|
3775 | the underlying OS handle. |
3358 | |
3776 | |
3359 | =item EV_USE_POLL |
3777 | =item EV_USE_POLL |
3360 | |
3778 | |
3361 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
3779 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
3362 | backend. Otherwise it will be enabled on non-win32 platforms. It |
3780 | backend. Otherwise it will be enabled on non-win32 platforms. It |
… | |
… | |
3409 | as well as for signal and thread safety in C<ev_async> watchers. |
3827 | as well as for signal and thread safety in C<ev_async> watchers. |
3410 | |
3828 | |
3411 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
3829 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
3412 | (from F<signal.h>), which is usually good enough on most platforms. |
3830 | (from F<signal.h>), which is usually good enough on most platforms. |
3413 | |
3831 | |
3414 | =item EV_H |
3832 | =item EV_H (h) |
3415 | |
3833 | |
3416 | The name of the F<ev.h> header file used to include it. The default if |
3834 | The name of the F<ev.h> header file used to include it. The default if |
3417 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
3835 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
3418 | used to virtually rename the F<ev.h> header file in case of conflicts. |
3836 | used to virtually rename the F<ev.h> header file in case of conflicts. |
3419 | |
3837 | |
3420 | =item EV_CONFIG_H |
3838 | =item EV_CONFIG_H (h) |
3421 | |
3839 | |
3422 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
3840 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
3423 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
3841 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
3424 | C<EV_H>, above. |
3842 | C<EV_H>, above. |
3425 | |
3843 | |
3426 | =item EV_EVENT_H |
3844 | =item EV_EVENT_H (h) |
3427 | |
3845 | |
3428 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
3846 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
3429 | of how the F<event.h> header can be found, the default is C<"event.h">. |
3847 | of how the F<event.h> header can be found, the default is C<"event.h">. |
3430 | |
3848 | |
3431 | =item EV_PROTOTYPES |
3849 | =item EV_PROTOTYPES (h) |
3432 | |
3850 | |
3433 | If defined to be C<0>, then F<ev.h> will not define any function |
3851 | If defined to be C<0>, then F<ev.h> will not define any function |
3434 | prototypes, but still define all the structs and other symbols. This is |
3852 | prototypes, but still define all the structs and other symbols. This is |
3435 | occasionally useful if you want to provide your own wrapper functions |
3853 | occasionally useful if you want to provide your own wrapper functions |
3436 | around libev functions. |
3854 | around libev functions. |
… | |
… | |
3458 | fine. |
3876 | fine. |
3459 | |
3877 | |
3460 | If your embedding application does not need any priorities, defining these |
3878 | If your embedding application does not need any priorities, defining these |
3461 | both to C<0> will save some memory and CPU. |
3879 | both to C<0> will save some memory and CPU. |
3462 | |
3880 | |
3463 | =item EV_PERIODIC_ENABLE |
3881 | =item EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE, |
|
|
3882 | EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, |
|
|
3883 | EV_ASYNC_ENABLE, EV_CHILD_ENABLE. |
3464 | |
3884 | |
3465 | If undefined or defined to be C<1>, then periodic timers are supported. If |
3885 | If undefined or defined to be C<1> (and the platform supports it), then |
3466 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
3886 | the respective watcher type is supported. If defined to be C<0>, then it |
3467 | code. |
3887 | is not. Disabling watcher types mainly saves codesize. |
3468 | |
|
|
3469 | =item EV_IDLE_ENABLE |
|
|
3470 | |
|
|
3471 | If undefined or defined to be C<1>, then idle watchers are supported. If |
|
|
3472 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
3473 | code. |
|
|
3474 | |
|
|
3475 | =item EV_EMBED_ENABLE |
|
|
3476 | |
|
|
3477 | If undefined or defined to be C<1>, then embed watchers are supported. If |
|
|
3478 | defined to be C<0>, then they are not. Embed watchers rely on most other |
|
|
3479 | watcher types, which therefore must not be disabled. |
|
|
3480 | |
|
|
3481 | =item EV_STAT_ENABLE |
|
|
3482 | |
|
|
3483 | If undefined or defined to be C<1>, then stat watchers are supported. If |
|
|
3484 | defined to be C<0>, then they are not. |
|
|
3485 | |
|
|
3486 | =item EV_FORK_ENABLE |
|
|
3487 | |
|
|
3488 | If undefined or defined to be C<1>, then fork watchers are supported. If |
|
|
3489 | defined to be C<0>, then they are not. |
|
|
3490 | |
|
|
3491 | =item EV_ASYNC_ENABLE |
|
|
3492 | |
|
|
3493 | If undefined or defined to be C<1>, then async watchers are supported. If |
|
|
3494 | defined to be C<0>, then they are not. |
|
|
3495 | |
3888 | |
3496 | =item EV_MINIMAL |
3889 | =item EV_MINIMAL |
3497 | |
3890 | |
3498 | If you need to shave off some kilobytes of code at the expense of some |
3891 | If you need to shave off some kilobytes of code at the expense of some |
3499 | speed, define this symbol to C<1>. Currently this is used to override some |
3892 | speed (but with the full API), define this symbol to C<1>. Currently this |
3500 | inlining decisions, saves roughly 30% code size on amd64. It also selects a |
3893 | is used to override some inlining decisions, saves roughly 30% code size |
3501 | much smaller 2-heap for timer management over the default 4-heap. |
3894 | on amd64. It also selects a much smaller 2-heap for timer management over |
|
|
3895 | the default 4-heap. |
|
|
3896 | |
|
|
3897 | You can save even more by disabling watcher types you do not need |
|
|
3898 | and setting C<EV_MAXPRI> == C<EV_MINPRI>. Also, disabling C<assert> |
|
|
3899 | (C<-DNDEBUG>) will usually reduce code size a lot. Disabling inotify, |
|
|
3900 | eventfd and signalfd will further help, and disabling backends one doesn't |
|
|
3901 | need (e.g. poll, epoll, kqueue, ports) will help further. |
|
|
3902 | |
|
|
3903 | Defining C<EV_MINIMAL> to C<2> will additionally reduce the core API to |
|
|
3904 | provide a bare-bones event library. See C<ev.h> for details on what parts |
|
|
3905 | of the API are still available, and do not complain if this subset changes |
|
|
3906 | over time. |
|
|
3907 | |
|
|
3908 | This example set of settings reduces the compiled size of libev from |
|
|
3909 | 23.9Kb to 7.7Kb on my GNU/Linux amd64 system (and leaves little |
|
|
3910 | in - there is also an effect on the amount of memory used). With |
|
|
3911 | an intelligent-enough linker (gcc+binutils do this when you use |
|
|
3912 | C<-Wl,--gc-sections -ffunction-sections>) further unused functions might |
|
|
3913 | be left out as well automatically - a binary starting a timer and an I/O |
|
|
3914 | watcher then might come out at only 5Kb. |
|
|
3915 | |
|
|
3916 | // tuning and API changes |
|
|
3917 | #define EV_MINIMAL 2 |
|
|
3918 | #define EV_MULTIPLICITY 0 |
|
|
3919 | #define EV_MINPRI 0 |
|
|
3920 | #define EV_MAXPRI 0 |
|
|
3921 | |
|
|
3922 | // OS-specific backends |
|
|
3923 | #define EV_USE_INOTIFY 0 |
|
|
3924 | #define EV_USE_EVENTFD 0 |
|
|
3925 | #define EV_USE_SIGNALFD 0 |
|
|
3926 | #define EV_USE_REALTIME 0 |
|
|
3927 | #define EV_USE_MONOTONIC 0 |
|
|
3928 | #define EV_USE_CLOCK_SYSCALL 0 |
|
|
3929 | |
|
|
3930 | // disable all backends except select |
|
|
3931 | #define EV_USE_POLL 0 |
|
|
3932 | #define EV_USE_PORT 0 |
|
|
3933 | #define EV_USE_KQUEUE 0 |
|
|
3934 | #define EV_USE_EPOLL 0 |
|
|
3935 | |
|
|
3936 | // disable all watcher types that cna be disabled |
|
|
3937 | #define EV_STAT_ENABLE 0 |
|
|
3938 | #define EV_PERIODIC_ENABLE 0 |
|
|
3939 | #define EV_IDLE_ENABLE 0 |
|
|
3940 | #define EV_CHECK_ENABLE 0 |
|
|
3941 | #define EV_PREPARE_ENABLE 0 |
|
|
3942 | #define EV_FORK_ENABLE 0 |
|
|
3943 | #define EV_SIGNAL_ENABLE 0 |
|
|
3944 | #define EV_CHILD_ENABLE 0 |
|
|
3945 | #define EV_ASYNC_ENABLE 0 |
|
|
3946 | #define EV_EMBED_ENABLE 0 |
|
|
3947 | |
|
|
3948 | =item EV_AVOID_STDIO |
|
|
3949 | |
|
|
3950 | If this is set to C<1> at compiletime, then libev will avoid using stdio |
|
|
3951 | functions (printf, scanf, perror etc.). This will increase the codesize |
|
|
3952 | somewhat, but if your program doesn't otherwise depend on stdio and your |
|
|
3953 | libc allows it, this avoids linking in the stdio library which is quite |
|
|
3954 | big. |
|
|
3955 | |
|
|
3956 | Note that error messages might become less precise when this option is |
|
|
3957 | enabled. |
|
|
3958 | |
|
|
3959 | =item EV_NSIG |
|
|
3960 | |
|
|
3961 | The highest supported signal number, +1 (or, the number of |
|
|
3962 | signals): Normally, libev tries to deduce the maximum number of signals |
|
|
3963 | automatically, but sometimes this fails, in which case it can be |
|
|
3964 | specified. Also, using a lower number than detected (C<32> should be |
|
|
3965 | good for about any system in existance) can save some memory, as libev |
|
|
3966 | statically allocates some 12-24 bytes per signal number. |
3502 | |
3967 | |
3503 | =item EV_PID_HASHSIZE |
3968 | =item EV_PID_HASHSIZE |
3504 | |
3969 | |
3505 | C<ev_child> watchers use a small hash table to distribute workload by |
3970 | C<ev_child> watchers use a small hash table to distribute workload by |
3506 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
3971 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
… | |
… | |
3692 | default loop and triggering an C<ev_async> watcher from the default loop |
4157 | default loop and triggering an C<ev_async> watcher from the default loop |
3693 | watcher callback into the event loop interested in the signal. |
4158 | watcher callback into the event loop interested in the signal. |
3694 | |
4159 | |
3695 | =back |
4160 | =back |
3696 | |
4161 | |
|
|
4162 | =head4 THREAD LOCKING EXAMPLE |
|
|
4163 | |
|
|
4164 | Here is a fictitious example of how to run an event loop in a different |
|
|
4165 | thread than where callbacks are being invoked and watchers are |
|
|
4166 | created/added/removed. |
|
|
4167 | |
|
|
4168 | For a real-world example, see the C<EV::Loop::Async> perl module, |
|
|
4169 | which uses exactly this technique (which is suited for many high-level |
|
|
4170 | languages). |
|
|
4171 | |
|
|
4172 | The example uses a pthread mutex to protect the loop data, a condition |
|
|
4173 | variable to wait for callback invocations, an async watcher to notify the |
|
|
4174 | event loop thread and an unspecified mechanism to wake up the main thread. |
|
|
4175 | |
|
|
4176 | First, you need to associate some data with the event loop: |
|
|
4177 | |
|
|
4178 | typedef struct { |
|
|
4179 | mutex_t lock; /* global loop lock */ |
|
|
4180 | ev_async async_w; |
|
|
4181 | thread_t tid; |
|
|
4182 | cond_t invoke_cv; |
|
|
4183 | } userdata; |
|
|
4184 | |
|
|
4185 | void prepare_loop (EV_P) |
|
|
4186 | { |
|
|
4187 | // for simplicity, we use a static userdata struct. |
|
|
4188 | static userdata u; |
|
|
4189 | |
|
|
4190 | ev_async_init (&u->async_w, async_cb); |
|
|
4191 | ev_async_start (EV_A_ &u->async_w); |
|
|
4192 | |
|
|
4193 | pthread_mutex_init (&u->lock, 0); |
|
|
4194 | pthread_cond_init (&u->invoke_cv, 0); |
|
|
4195 | |
|
|
4196 | // now associate this with the loop |
|
|
4197 | ev_set_userdata (EV_A_ u); |
|
|
4198 | ev_set_invoke_pending_cb (EV_A_ l_invoke); |
|
|
4199 | ev_set_loop_release_cb (EV_A_ l_release, l_acquire); |
|
|
4200 | |
|
|
4201 | // then create the thread running ev_loop |
|
|
4202 | pthread_create (&u->tid, 0, l_run, EV_A); |
|
|
4203 | } |
|
|
4204 | |
|
|
4205 | The callback for the C<ev_async> watcher does nothing: the watcher is used |
|
|
4206 | solely to wake up the event loop so it takes notice of any new watchers |
|
|
4207 | that might have been added: |
|
|
4208 | |
|
|
4209 | static void |
|
|
4210 | async_cb (EV_P_ ev_async *w, int revents) |
|
|
4211 | { |
|
|
4212 | // just used for the side effects |
|
|
4213 | } |
|
|
4214 | |
|
|
4215 | The C<l_release> and C<l_acquire> callbacks simply unlock/lock the mutex |
|
|
4216 | protecting the loop data, respectively. |
|
|
4217 | |
|
|
4218 | static void |
|
|
4219 | l_release (EV_P) |
|
|
4220 | { |
|
|
4221 | userdata *u = ev_userdata (EV_A); |
|
|
4222 | pthread_mutex_unlock (&u->lock); |
|
|
4223 | } |
|
|
4224 | |
|
|
4225 | static void |
|
|
4226 | l_acquire (EV_P) |
|
|
4227 | { |
|
|
4228 | userdata *u = ev_userdata (EV_A); |
|
|
4229 | pthread_mutex_lock (&u->lock); |
|
|
4230 | } |
|
|
4231 | |
|
|
4232 | The event loop thread first acquires the mutex, and then jumps straight |
|
|
4233 | into C<ev_loop>: |
|
|
4234 | |
|
|
4235 | void * |
|
|
4236 | l_run (void *thr_arg) |
|
|
4237 | { |
|
|
4238 | struct ev_loop *loop = (struct ev_loop *)thr_arg; |
|
|
4239 | |
|
|
4240 | l_acquire (EV_A); |
|
|
4241 | pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
|
|
4242 | ev_loop (EV_A_ 0); |
|
|
4243 | l_release (EV_A); |
|
|
4244 | |
|
|
4245 | return 0; |
|
|
4246 | } |
|
|
4247 | |
|
|
4248 | Instead of invoking all pending watchers, the C<l_invoke> callback will |
|
|
4249 | signal the main thread via some unspecified mechanism (signals? pipe |
|
|
4250 | writes? C<Async::Interrupt>?) and then waits until all pending watchers |
|
|
4251 | have been called (in a while loop because a) spurious wakeups are possible |
|
|
4252 | and b) skipping inter-thread-communication when there are no pending |
|
|
4253 | watchers is very beneficial): |
|
|
4254 | |
|
|
4255 | static void |
|
|
4256 | l_invoke (EV_P) |
|
|
4257 | { |
|
|
4258 | userdata *u = ev_userdata (EV_A); |
|
|
4259 | |
|
|
4260 | while (ev_pending_count (EV_A)) |
|
|
4261 | { |
|
|
4262 | wake_up_other_thread_in_some_magic_or_not_so_magic_way (); |
|
|
4263 | pthread_cond_wait (&u->invoke_cv, &u->lock); |
|
|
4264 | } |
|
|
4265 | } |
|
|
4266 | |
|
|
4267 | Now, whenever the main thread gets told to invoke pending watchers, it |
|
|
4268 | will grab the lock, call C<ev_invoke_pending> and then signal the loop |
|
|
4269 | thread to continue: |
|
|
4270 | |
|
|
4271 | static void |
|
|
4272 | real_invoke_pending (EV_P) |
|
|
4273 | { |
|
|
4274 | userdata *u = ev_userdata (EV_A); |
|
|
4275 | |
|
|
4276 | pthread_mutex_lock (&u->lock); |
|
|
4277 | ev_invoke_pending (EV_A); |
|
|
4278 | pthread_cond_signal (&u->invoke_cv); |
|
|
4279 | pthread_mutex_unlock (&u->lock); |
|
|
4280 | } |
|
|
4281 | |
|
|
4282 | Whenever you want to start/stop a watcher or do other modifications to an |
|
|
4283 | event loop, you will now have to lock: |
|
|
4284 | |
|
|
4285 | ev_timer timeout_watcher; |
|
|
4286 | userdata *u = ev_userdata (EV_A); |
|
|
4287 | |
|
|
4288 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
|
|
4289 | |
|
|
4290 | pthread_mutex_lock (&u->lock); |
|
|
4291 | ev_timer_start (EV_A_ &timeout_watcher); |
|
|
4292 | ev_async_send (EV_A_ &u->async_w); |
|
|
4293 | pthread_mutex_unlock (&u->lock); |
|
|
4294 | |
|
|
4295 | Note that sending the C<ev_async> watcher is required because otherwise |
|
|
4296 | an event loop currently blocking in the kernel will have no knowledge |
|
|
4297 | about the newly added timer. By waking up the loop it will pick up any new |
|
|
4298 | watchers in the next event loop iteration. |
|
|
4299 | |
3697 | =head3 COROUTINES |
4300 | =head3 COROUTINES |
3698 | |
4301 | |
3699 | Libev is very accommodating to coroutines ("cooperative threads"): |
4302 | Libev is very accommodating to coroutines ("cooperative threads"): |
3700 | libev fully supports nesting calls to its functions from different |
4303 | libev fully supports nesting calls to its functions from different |
3701 | coroutines (e.g. you can call C<ev_loop> on the same loop from two |
4304 | coroutines (e.g. you can call C<ev_loop> on the same loop from two |
3702 | different coroutines, and switch freely between both coroutines running the |
4305 | different coroutines, and switch freely between both coroutines running |
3703 | loop, as long as you don't confuse yourself). The only exception is that |
4306 | the loop, as long as you don't confuse yourself). The only exception is |
3704 | you must not do this from C<ev_periodic> reschedule callbacks. |
4307 | that you must not do this from C<ev_periodic> reschedule callbacks. |
3705 | |
4308 | |
3706 | Care has been taken to ensure that libev does not keep local state inside |
4309 | Care has been taken to ensure that libev does not keep local state inside |
3707 | C<ev_loop>, and other calls do not usually allow for coroutine switches as |
4310 | C<ev_loop>, and other calls do not usually allow for coroutine switches as |
3708 | they do not call any callbacks. |
4311 | they do not call any callbacks. |
3709 | |
4312 | |
… | |
… | |
3786 | way (note also that glib is the slowest event library known to man). |
4389 | way (note also that glib is the slowest event library known to man). |
3787 | |
4390 | |
3788 | There is no supported compilation method available on windows except |
4391 | There is no supported compilation method available on windows except |
3789 | embedding it into other applications. |
4392 | embedding it into other applications. |
3790 | |
4393 | |
|
|
4394 | Sensible signal handling is officially unsupported by Microsoft - libev |
|
|
4395 | tries its best, but under most conditions, signals will simply not work. |
|
|
4396 | |
3791 | Not a libev limitation but worth mentioning: windows apparently doesn't |
4397 | Not a libev limitation but worth mentioning: windows apparently doesn't |
3792 | accept large writes: instead of resulting in a partial write, windows will |
4398 | accept large writes: instead of resulting in a partial write, windows will |
3793 | either accept everything or return C<ENOBUFS> if the buffer is too large, |
4399 | either accept everything or return C<ENOBUFS> if the buffer is too large, |
3794 | so make sure you only write small amounts into your sockets (less than a |
4400 | so make sure you only write small amounts into your sockets (less than a |
3795 | megabyte seems safe, but this apparently depends on the amount of memory |
4401 | megabyte seems safe, but this apparently depends on the amount of memory |
… | |
… | |
3799 | the abysmal performance of winsockets, using a large number of sockets |
4405 | the abysmal performance of winsockets, using a large number of sockets |
3800 | is not recommended (and not reasonable). If your program needs to use |
4406 | is not recommended (and not reasonable). If your program needs to use |
3801 | more than a hundred or so sockets, then likely it needs to use a totally |
4407 | more than a hundred or so sockets, then likely it needs to use a totally |
3802 | different implementation for windows, as libev offers the POSIX readiness |
4408 | different implementation for windows, as libev offers the POSIX readiness |
3803 | notification model, which cannot be implemented efficiently on windows |
4409 | notification model, which cannot be implemented efficiently on windows |
3804 | (Microsoft monopoly games). |
4410 | (due to Microsoft monopoly games). |
3805 | |
4411 | |
3806 | A typical way to use libev under windows is to embed it (see the embedding |
4412 | A typical way to use libev under windows is to embed it (see the embedding |
3807 | section for details) and use the following F<evwrap.h> header file instead |
4413 | section for details) and use the following F<evwrap.h> header file instead |
3808 | of F<ev.h>: |
4414 | of F<ev.h>: |
3809 | |
4415 | |
… | |
… | |
3845 | |
4451 | |
3846 | Early versions of winsocket's select only supported waiting for a maximum |
4452 | Early versions of winsocket's select only supported waiting for a maximum |
3847 | of C<64> handles (probably owning to the fact that all windows kernels |
4453 | of C<64> handles (probably owning to the fact that all windows kernels |
3848 | can only wait for C<64> things at the same time internally; Microsoft |
4454 | can only wait for C<64> things at the same time internally; Microsoft |
3849 | recommends spawning a chain of threads and wait for 63 handles and the |
4455 | recommends spawning a chain of threads and wait for 63 handles and the |
3850 | previous thread in each. Great). |
4456 | previous thread in each. Sounds great!). |
3851 | |
4457 | |
3852 | Newer versions support more handles, but you need to define C<FD_SETSIZE> |
4458 | Newer versions support more handles, but you need to define C<FD_SETSIZE> |
3853 | to some high number (e.g. C<2048>) before compiling the winsocket select |
4459 | to some high number (e.g. C<2048>) before compiling the winsocket select |
3854 | call (which might be in libev or elsewhere, for example, perl does its own |
4460 | call (which might be in libev or elsewhere, for example, perl and many |
3855 | select emulation on windows). |
4461 | other interpreters do their own select emulation on windows). |
3856 | |
4462 | |
3857 | Another limit is the number of file descriptors in the Microsoft runtime |
4463 | Another limit is the number of file descriptors in the Microsoft runtime |
3858 | libraries, which by default is C<64> (there must be a hidden I<64> fetish |
4464 | libraries, which by default is C<64> (there must be a hidden I<64> |
3859 | or something like this inside Microsoft). You can increase this by calling |
4465 | fetish or something like this inside Microsoft). You can increase this |
3860 | C<_setmaxstdio>, which can increase this limit to C<2048> (another |
4466 | by calling C<_setmaxstdio>, which can increase this limit to C<2048> |
3861 | arbitrary limit), but is broken in many versions of the Microsoft runtime |
4467 | (another arbitrary limit), but is broken in many versions of the Microsoft |
3862 | libraries. |
|
|
3863 | |
|
|
3864 | This might get you to about C<512> or C<2048> sockets (depending on |
4468 | runtime libraries. This might get you to about C<512> or C<2048> sockets |
3865 | windows version and/or the phase of the moon). To get more, you need to |
4469 | (depending on windows version and/or the phase of the moon). To get more, |
3866 | wrap all I/O functions and provide your own fd management, but the cost of |
4470 | you need to wrap all I/O functions and provide your own fd management, but |
3867 | calling select (O(n²)) will likely make this unworkable. |
4471 | the cost of calling select (O(n²)) will likely make this unworkable. |
3868 | |
4472 | |
3869 | =back |
4473 | =back |
3870 | |
4474 | |
3871 | =head2 PORTABILITY REQUIREMENTS |
4475 | =head2 PORTABILITY REQUIREMENTS |
3872 | |
4476 | |
… | |
… | |
3915 | =item C<double> must hold a time value in seconds with enough accuracy |
4519 | =item C<double> must hold a time value in seconds with enough accuracy |
3916 | |
4520 | |
3917 | The type C<double> is used to represent timestamps. It is required to |
4521 | The type C<double> is used to represent timestamps. It is required to |
3918 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
4522 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
3919 | enough for at least into the year 4000. This requirement is fulfilled by |
4523 | enough for at least into the year 4000. This requirement is fulfilled by |
3920 | implementations implementing IEEE 754 (basically all existing ones). |
4524 | implementations implementing IEEE 754, which is basically all existing |
|
|
4525 | ones. With IEEE 754 doubles, you get microsecond accuracy until at least |
|
|
4526 | 2200. |
3921 | |
4527 | |
3922 | =back |
4528 | =back |
3923 | |
4529 | |
3924 | If you know of other additional requirements drop me a note. |
4530 | If you know of other additional requirements drop me a note. |
3925 | |
4531 | |
… | |
… | |
3993 | involves iterating over all running async watchers or all signal numbers. |
4599 | involves iterating over all running async watchers or all signal numbers. |
3994 | |
4600 | |
3995 | =back |
4601 | =back |
3996 | |
4602 | |
3997 | |
4603 | |
|
|
4604 | =head1 GLOSSARY |
|
|
4605 | |
|
|
4606 | =over 4 |
|
|
4607 | |
|
|
4608 | =item active |
|
|
4609 | |
|
|
4610 | A watcher is active as long as it has been started (has been attached to |
|
|
4611 | an event loop) but not yet stopped (disassociated from the event loop). |
|
|
4612 | |
|
|
4613 | =item application |
|
|
4614 | |
|
|
4615 | In this document, an application is whatever is using libev. |
|
|
4616 | |
|
|
4617 | =item callback |
|
|
4618 | |
|
|
4619 | The address of a function that is called when some event has been |
|
|
4620 | detected. Callbacks are being passed the event loop, the watcher that |
|
|
4621 | received the event, and the actual event bitset. |
|
|
4622 | |
|
|
4623 | =item callback invocation |
|
|
4624 | |
|
|
4625 | The act of calling the callback associated with a watcher. |
|
|
4626 | |
|
|
4627 | =item event |
|
|
4628 | |
|
|
4629 | A change of state of some external event, such as data now being available |
|
|
4630 | for reading on a file descriptor, time having passed or simply not having |
|
|
4631 | any other events happening anymore. |
|
|
4632 | |
|
|
4633 | In libev, events are represented as single bits (such as C<EV_READ> or |
|
|
4634 | C<EV_TIMEOUT>). |
|
|
4635 | |
|
|
4636 | =item event library |
|
|
4637 | |
|
|
4638 | A software package implementing an event model and loop. |
|
|
4639 | |
|
|
4640 | =item event loop |
|
|
4641 | |
|
|
4642 | An entity that handles and processes external events and converts them |
|
|
4643 | into callback invocations. |
|
|
4644 | |
|
|
4645 | =item event model |
|
|
4646 | |
|
|
4647 | The model used to describe how an event loop handles and processes |
|
|
4648 | watchers and events. |
|
|
4649 | |
|
|
4650 | =item pending |
|
|
4651 | |
|
|
4652 | A watcher is pending as soon as the corresponding event has been detected, |
|
|
4653 | and stops being pending as soon as the watcher will be invoked or its |
|
|
4654 | pending status is explicitly cleared by the application. |
|
|
4655 | |
|
|
4656 | A watcher can be pending, but not active. Stopping a watcher also clears |
|
|
4657 | its pending status. |
|
|
4658 | |
|
|
4659 | =item real time |
|
|
4660 | |
|
|
4661 | The physical time that is observed. It is apparently strictly monotonic :) |
|
|
4662 | |
|
|
4663 | =item wall-clock time |
|
|
4664 | |
|
|
4665 | The time and date as shown on clocks. Unlike real time, it can actually |
|
|
4666 | be wrong and jump forwards and backwards, e.g. when the you adjust your |
|
|
4667 | clock. |
|
|
4668 | |
|
|
4669 | =item watcher |
|
|
4670 | |
|
|
4671 | A data structure that describes interest in certain events. Watchers need |
|
|
4672 | to be started (attached to an event loop) before they can receive events. |
|
|
4673 | |
|
|
4674 | =item watcher invocation |
|
|
4675 | |
|
|
4676 | The act of calling the callback associated with a watcher. |
|
|
4677 | |
|
|
4678 | =back |
|
|
4679 | |
3998 | =head1 AUTHOR |
4680 | =head1 AUTHOR |
3999 | |
4681 | |
4000 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |
4682 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |
4001 | |
4683 | |