… | |
… | |
468 | ev_ref (myloop); |
468 | ev_ref (myloop); |
469 | ev_signal_stop (myloop, &exitsig); |
469 | ev_signal_stop (myloop, &exitsig); |
470 | |
470 | |
471 | =back |
471 | =back |
472 | |
472 | |
|
|
473 | |
473 | =head1 ANATOMY OF A WATCHER |
474 | =head1 ANATOMY OF A WATCHER |
474 | |
475 | |
475 | A watcher is a structure that you create and register to record your |
476 | A watcher is a structure that you create and register to record your |
476 | interest in some event. For instance, if you want to wait for STDIN to |
477 | interest in some event. For instance, if you want to wait for STDIN to |
477 | become readable, you would create an C<ev_io> watcher for that: |
478 | become readable, you would create an C<ev_io> watcher for that: |
… | |
… | |
543 | The signal specified in the C<ev_signal> watcher has been received by a thread. |
544 | The signal specified in the C<ev_signal> watcher has been received by a thread. |
544 | |
545 | |
545 | =item C<EV_CHILD> |
546 | =item C<EV_CHILD> |
546 | |
547 | |
547 | The pid specified in the C<ev_child> watcher has received a status change. |
548 | The pid specified in the C<ev_child> watcher has received a status change. |
|
|
549 | |
|
|
550 | =item C<EV_STAT> |
|
|
551 | |
|
|
552 | The path specified in the C<ev_stat> watcher changed its attributes somehow. |
548 | |
553 | |
549 | =item C<EV_IDLE> |
554 | =item C<EV_IDLE> |
550 | |
555 | |
551 | The C<ev_idle> watcher has determined that you have nothing better to do. |
556 | The C<ev_idle> watcher has determined that you have nothing better to do. |
552 | |
557 | |
… | |
… | |
576 | with the error from read() or write(). This will not work in multithreaded |
581 | with the error from read() or write(). This will not work in multithreaded |
577 | programs, though, so beware. |
582 | programs, though, so beware. |
578 | |
583 | |
579 | =back |
584 | =back |
580 | |
585 | |
581 | =head2 SUMMARY OF GENERIC WATCHER FUNCTIONS |
586 | =head2 GENERIC WATCHER FUNCTIONS |
582 | |
587 | |
583 | In the following description, C<TYPE> stands for the watcher type, |
588 | In the following description, C<TYPE> stands for the watcher type, |
584 | e.g. C<timer> for C<ev_timer> watchers and C<io> for C<ev_io> watchers. |
589 | e.g. C<timer> for C<ev_timer> watchers and C<io> for C<ev_io> watchers. |
585 | |
590 | |
586 | =over 4 |
591 | =over 4 |
… | |
… | |
595 | which rolls both calls into one. |
600 | which rolls both calls into one. |
596 | |
601 | |
597 | You can reinitialise a watcher at any time as long as it has been stopped |
602 | You can reinitialise a watcher at any time as long as it has been stopped |
598 | (or never started) and there are no pending events outstanding. |
603 | (or never started) and there are no pending events outstanding. |
599 | |
604 | |
600 | The callbakc is always of type C<void (*)(ev_loop *loop, ev_TYPE *watcher, |
605 | The callback is always of type C<void (*)(ev_loop *loop, ev_TYPE *watcher, |
601 | int revents)>. |
606 | int revents)>. |
602 | |
607 | |
603 | =item C<ev_TYPE_set> (ev_TYPE *, [args]) |
608 | =item C<ev_TYPE_set> (ev_TYPE *, [args]) |
604 | |
609 | |
605 | This macro initialises the type-specific parts of a watcher. You need to |
610 | This macro initialises the type-specific parts of a watcher. You need to |
… | |
… | |
688 | |
693 | |
689 | |
694 | |
690 | =head1 WATCHER TYPES |
695 | =head1 WATCHER TYPES |
691 | |
696 | |
692 | This section describes each watcher in detail, but will not repeat |
697 | This section describes each watcher in detail, but will not repeat |
693 | information given in the last section. |
698 | information given in the last section. Any initialisation/set macros, |
|
|
699 | functions and members specific to the watcher type are explained. |
694 | |
700 | |
|
|
701 | Members are additionally marked with either I<[read-only]>, meaning that, |
|
|
702 | while the watcher is active, you can look at the member and expect some |
|
|
703 | sensible content, but you must not modify it (you can modify it while the |
|
|
704 | watcher is stopped to your hearts content), or I<[read-write]>, which |
|
|
705 | means you can expect it to have some sensible content while the watcher |
|
|
706 | is active, but you can also modify it. Modifying it may not do something |
|
|
707 | sensible or take immediate effect (or do anything at all), but libev will |
|
|
708 | not crash or malfunction in any way. |
695 | |
709 | |
|
|
710 | |
696 | =head2 C<ev_io> - is this file descriptor readable or writable |
711 | =head2 C<ev_io> - is this file descriptor readable or writable? |
697 | |
712 | |
698 | I/O watchers check whether a file descriptor is readable or writable |
713 | I/O watchers check whether a file descriptor is readable or writable |
699 | in each iteration of the event loop (This behaviour is called |
714 | in each iteration of the event loop, or, more precisely, when reading |
700 | level-triggering because you keep receiving events as long as the |
715 | would not block the process and writing would at least be able to write |
701 | condition persists. Remember you can stop the watcher if you don't want to |
716 | some data. This behaviour is called level-triggering because you keep |
702 | act on the event and neither want to receive future events). |
717 | receiving events as long as the condition persists. Remember you can stop |
|
|
718 | the watcher if you don't want to act on the event and neither want to |
|
|
719 | receive future events. |
703 | |
720 | |
704 | In general you can register as many read and/or write event watchers per |
721 | In general you can register as many read and/or write event watchers per |
705 | fd as you want (as long as you don't confuse yourself). Setting all file |
722 | fd as you want (as long as you don't confuse yourself). Setting all file |
706 | descriptors to non-blocking mode is also usually a good idea (but not |
723 | descriptors to non-blocking mode is also usually a good idea (but not |
707 | required if you know what you are doing). |
724 | required if you know what you are doing). |
708 | |
725 | |
709 | You have to be careful with dup'ed file descriptors, though. Some backends |
726 | You have to be careful with dup'ed file descriptors, though. Some backends |
710 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
727 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
711 | descriptors correctly if you register interest in two or more fds pointing |
728 | descriptors correctly if you register interest in two or more fds pointing |
712 | to the same underlying file/socket etc. description (that is, they share |
729 | to the same underlying file/socket/etc. description (that is, they share |
713 | the same underlying "file open"). |
730 | the same underlying "file open"). |
714 | |
731 | |
715 | If you must do this, then force the use of a known-to-be-good backend |
732 | If you must do this, then force the use of a known-to-be-good backend |
716 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
733 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
717 | C<EVBACKEND_POLL>). |
734 | C<EVBACKEND_POLL>). |
718 | |
735 | |
|
|
736 | Another thing you have to watch out for is that it is quite easy to |
|
|
737 | receive "spurious" readyness notifications, that is your callback might |
|
|
738 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
|
|
739 | because there is no data. Not only are some backends known to create a |
|
|
740 | lot of those (for example solaris ports), it is very easy to get into |
|
|
741 | this situation even with a relatively standard program structure. Thus |
|
|
742 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
|
|
743 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
|
|
744 | |
|
|
745 | If you cannot run the fd in non-blocking mode (for example you should not |
|
|
746 | play around with an Xlib connection), then you have to seperately re-test |
|
|
747 | wether a file descriptor is really ready with a known-to-be good interface |
|
|
748 | such as poll (fortunately in our Xlib example, Xlib already does this on |
|
|
749 | its own, so its quite safe to use). |
|
|
750 | |
719 | =over 4 |
751 | =over 4 |
720 | |
752 | |
721 | =item ev_io_init (ev_io *, callback, int fd, int events) |
753 | =item ev_io_init (ev_io *, callback, int fd, int events) |
722 | |
754 | |
723 | =item ev_io_set (ev_io *, int fd, int events) |
755 | =item ev_io_set (ev_io *, int fd, int events) |
724 | |
756 | |
725 | Configures an C<ev_io> watcher. The fd is the file descriptor to rceeive |
757 | Configures an C<ev_io> watcher. The C<fd> is the file descriptor to |
726 | events for and events is either C<EV_READ>, C<EV_WRITE> or C<EV_READ | |
758 | rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or |
727 | EV_WRITE> to receive the given events. |
759 | C<EV_READ | EV_WRITE> to receive the given events. |
728 | |
760 | |
729 | Please note that most of the more scalable backend mechanisms (for example |
761 | =item int fd [read-only] |
730 | epoll and solaris ports) can result in spurious readyness notifications |
762 | |
731 | for file descriptors, so you practically need to use non-blocking I/O (and |
763 | The file descriptor being watched. |
732 | treat callback invocation as hint only), or retest separately with a safe |
764 | |
733 | interface before doing I/O (XLib can do this), or force the use of either |
765 | =item int events [read-only] |
734 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>, which don't suffer from this |
766 | |
735 | problem. Also note that it is quite easy to have your callback invoked |
767 | The events being watched. |
736 | when the readyness condition is no longer valid even when employing |
|
|
737 | typical ways of handling events, so its a good idea to use non-blocking |
|
|
738 | I/O unconditionally. |
|
|
739 | |
768 | |
740 | =back |
769 | =back |
741 | |
770 | |
742 | Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well |
771 | Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well |
743 | readable, but only once. Since it is likely line-buffered, you could |
772 | readable, but only once. Since it is likely line-buffered, you could |
… | |
… | |
756 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
785 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
757 | ev_io_start (loop, &stdin_readable); |
786 | ev_io_start (loop, &stdin_readable); |
758 | ev_loop (loop, 0); |
787 | ev_loop (loop, 0); |
759 | |
788 | |
760 | |
789 | |
761 | =head2 C<ev_timer> - relative and optionally recurring timeouts |
790 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
762 | |
791 | |
763 | Timer watchers are simple relative timers that generate an event after a |
792 | Timer watchers are simple relative timers that generate an event after a |
764 | given time, and optionally repeating in regular intervals after that. |
793 | given time, and optionally repeating in regular intervals after that. |
765 | |
794 | |
766 | The timers are based on real time, that is, if you register an event that |
795 | The timers are based on real time, that is, if you register an event that |
… | |
… | |
807 | |
836 | |
808 | If the timer is repeating, either start it if necessary (with the repeat |
837 | If the timer is repeating, either start it if necessary (with the repeat |
809 | value), or reset the running timer to the repeat value. |
838 | value), or reset the running timer to the repeat value. |
810 | |
839 | |
811 | This sounds a bit complicated, but here is a useful and typical |
840 | This sounds a bit complicated, but here is a useful and typical |
812 | example: Imagine you have a tcp connection and you want a so-called idle |
841 | example: Imagine you have a tcp connection and you want a so-called |
813 | timeout, that is, you want to be called when there have been, say, 60 |
842 | idle timeout, that is, you want to be called when there have been, |
814 | seconds of inactivity on the socket. The easiest way to do this is to |
843 | say, 60 seconds of inactivity on the socket. The easiest way to do |
815 | configure an C<ev_timer> with after=repeat=60 and calling ev_timer_again each |
844 | this is to configure an C<ev_timer> with C<after>=C<repeat>=C<60> and calling |
816 | time you successfully read or write some data. If you go into an idle |
845 | C<ev_timer_again> each time you successfully read or write some data. If |
817 | state where you do not expect data to travel on the socket, you can stop |
846 | you go into an idle state where you do not expect data to travel on the |
818 | the timer, and again will automatically restart it if need be. |
847 | socket, you can stop the timer, and again will automatically restart it if |
|
|
848 | need be. |
|
|
849 | |
|
|
850 | You can also ignore the C<after> value and C<ev_timer_start> altogether |
|
|
851 | and only ever use the C<repeat> value: |
|
|
852 | |
|
|
853 | ev_timer_init (timer, callback, 0., 5.); |
|
|
854 | ev_timer_again (loop, timer); |
|
|
855 | ... |
|
|
856 | timer->again = 17.; |
|
|
857 | ev_timer_again (loop, timer); |
|
|
858 | ... |
|
|
859 | timer->again = 10.; |
|
|
860 | ev_timer_again (loop, timer); |
|
|
861 | |
|
|
862 | This is more efficient then stopping/starting the timer eahc time you want |
|
|
863 | to modify its timeout value. |
|
|
864 | |
|
|
865 | =item ev_tstamp repeat [read-write] |
|
|
866 | |
|
|
867 | The current C<repeat> value. Will be used each time the watcher times out |
|
|
868 | or C<ev_timer_again> is called and determines the next timeout (if any), |
|
|
869 | which is also when any modifications are taken into account. |
819 | |
870 | |
820 | =back |
871 | =back |
821 | |
872 | |
822 | Example: create a timer that fires after 60 seconds. |
873 | Example: create a timer that fires after 60 seconds. |
823 | |
874 | |
… | |
… | |
848 | // and in some piece of code that gets executed on any "activity": |
899 | // and in some piece of code that gets executed on any "activity": |
849 | // reset the timeout to start ticking again at 10 seconds |
900 | // reset the timeout to start ticking again at 10 seconds |
850 | ev_timer_again (&mytimer); |
901 | ev_timer_again (&mytimer); |
851 | |
902 | |
852 | |
903 | |
853 | =head2 C<ev_periodic> - to cron or not to cron |
904 | =head2 C<ev_periodic> - to cron or not to cron? |
854 | |
905 | |
855 | Periodic watchers are also timers of a kind, but they are very versatile |
906 | Periodic watchers are also timers of a kind, but they are very versatile |
856 | (and unfortunately a bit complex). |
907 | (and unfortunately a bit complex). |
857 | |
908 | |
858 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
909 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
… | |
… | |
950 | Simply stops and restarts the periodic watcher again. This is only useful |
1001 | Simply stops and restarts the periodic watcher again. This is only useful |
951 | when you changed some parameters or the reschedule callback would return |
1002 | when you changed some parameters or the reschedule callback would return |
952 | a different time than the last time it was called (e.g. in a crond like |
1003 | a different time than the last time it was called (e.g. in a crond like |
953 | program when the crontabs have changed). |
1004 | program when the crontabs have changed). |
954 | |
1005 | |
|
|
1006 | =item ev_tstamp interval [read-write] |
|
|
1007 | |
|
|
1008 | The current interval value. Can be modified any time, but changes only |
|
|
1009 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
|
|
1010 | called. |
|
|
1011 | |
|
|
1012 | =item ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write] |
|
|
1013 | |
|
|
1014 | The current reschedule callback, or C<0>, if this functionality is |
|
|
1015 | switched off. Can be changed any time, but changes only take effect when |
|
|
1016 | the periodic timer fires or C<ev_periodic_again> is being called. |
|
|
1017 | |
955 | =back |
1018 | =back |
956 | |
1019 | |
957 | Example: call a callback every hour, or, more precisely, whenever the |
1020 | Example: call a callback every hour, or, more precisely, whenever the |
958 | system clock is divisible by 3600. The callback invocation times have |
1021 | system clock is divisible by 3600. The callback invocation times have |
959 | potentially a lot of jittering, but good long-term stability. |
1022 | potentially a lot of jittering, but good long-term stability. |
… | |
… | |
986 | ev_periodic_init (&hourly_tick, clock_cb, |
1049 | ev_periodic_init (&hourly_tick, clock_cb, |
987 | fmod (ev_now (loop), 3600.), 3600., 0); |
1050 | fmod (ev_now (loop), 3600.), 3600., 0); |
988 | ev_periodic_start (loop, &hourly_tick); |
1051 | ev_periodic_start (loop, &hourly_tick); |
989 | |
1052 | |
990 | |
1053 | |
991 | =head2 C<ev_signal> - signal me when a signal gets signalled |
1054 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
992 | |
1055 | |
993 | Signal watchers will trigger an event when the process receives a specific |
1056 | Signal watchers will trigger an event when the process receives a specific |
994 | signal one or more times. Even though signals are very asynchronous, libev |
1057 | signal one or more times. Even though signals are very asynchronous, libev |
995 | will try it's best to deliver signals synchronously, i.e. as part of the |
1058 | will try it's best to deliver signals synchronously, i.e. as part of the |
996 | normal event processing, like any other event. |
1059 | normal event processing, like any other event. |
… | |
… | |
1009 | =item ev_signal_set (ev_signal *, int signum) |
1072 | =item ev_signal_set (ev_signal *, int signum) |
1010 | |
1073 | |
1011 | Configures the watcher to trigger on the given signal number (usually one |
1074 | Configures the watcher to trigger on the given signal number (usually one |
1012 | of the C<SIGxxx> constants). |
1075 | of the C<SIGxxx> constants). |
1013 | |
1076 | |
|
|
1077 | =item int signum [read-only] |
|
|
1078 | |
|
|
1079 | The signal the watcher watches out for. |
|
|
1080 | |
1014 | =back |
1081 | =back |
1015 | |
1082 | |
1016 | |
1083 | |
1017 | =head2 C<ev_child> - wait for pid status changes |
1084 | =head2 C<ev_child> - watch out for process status changes |
1018 | |
1085 | |
1019 | Child watchers trigger when your process receives a SIGCHLD in response to |
1086 | Child watchers trigger when your process receives a SIGCHLD in response to |
1020 | some child status changes (most typically when a child of yours dies). |
1087 | some child status changes (most typically when a child of yours dies). |
1021 | |
1088 | |
1022 | =over 4 |
1089 | =over 4 |
… | |
… | |
1030 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
1097 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
1031 | the status word (use the macros from C<sys/wait.h> and see your systems |
1098 | the status word (use the macros from C<sys/wait.h> and see your systems |
1032 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
1099 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
1033 | process causing the status change. |
1100 | process causing the status change. |
1034 | |
1101 | |
|
|
1102 | =item int pid [read-only] |
|
|
1103 | |
|
|
1104 | The process id this watcher watches out for, or C<0>, meaning any process id. |
|
|
1105 | |
|
|
1106 | =item int rpid [read-write] |
|
|
1107 | |
|
|
1108 | The process id that detected a status change. |
|
|
1109 | |
|
|
1110 | =item int rstatus [read-write] |
|
|
1111 | |
|
|
1112 | The process exit/trace status caused by C<rpid> (see your systems |
|
|
1113 | C<waitpid> and C<sys/wait.h> documentation for details). |
|
|
1114 | |
1035 | =back |
1115 | =back |
1036 | |
1116 | |
1037 | Example: try to exit cleanly on SIGINT and SIGTERM. |
1117 | Example: try to exit cleanly on SIGINT and SIGTERM. |
1038 | |
1118 | |
1039 | static void |
1119 | static void |
… | |
… | |
1045 | struct ev_signal signal_watcher; |
1125 | struct ev_signal signal_watcher; |
1046 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1126 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1047 | ev_signal_start (loop, &sigint_cb); |
1127 | ev_signal_start (loop, &sigint_cb); |
1048 | |
1128 | |
1049 | |
1129 | |
|
|
1130 | =head2 C<ev_stat> - did the file attributes just change? |
|
|
1131 | |
|
|
1132 | This watches a filesystem path for attribute changes. That is, it calls |
|
|
1133 | C<stat> regularly (or when the OS says it changed) and sees if it changed |
|
|
1134 | compared to the last time, invoking the callback if it did. |
|
|
1135 | |
|
|
1136 | The path does not need to exist: changing from "path exists" to "path does |
|
|
1137 | not exist" is a status change like any other. The condition "path does |
|
|
1138 | not exist" is signified by the C<st_nlink> field being zero (which is |
|
|
1139 | otherwise always forced to be at least one) and all the other fields of |
|
|
1140 | the stat buffer having unspecified contents. |
|
|
1141 | |
|
|
1142 | Since there is no standard to do this, the portable implementation simply |
|
|
1143 | calls C<stat (2)> regulalry on the path to see if it changed somehow. You |
|
|
1144 | can specify a recommended polling interval for this case. If you specify |
|
|
1145 | a polling interval of C<0> (highly recommended!) then a I<suitable, |
|
|
1146 | unspecified default> value will be used (which you can expect to be around |
|
|
1147 | five seconds, although this might change dynamically). Libev will also |
|
|
1148 | impose a minimum interval which is currently around C<0.1>, but thats |
|
|
1149 | usually overkill. |
|
|
1150 | |
|
|
1151 | This watcher type is not meant for massive numbers of stat watchers, |
|
|
1152 | as even with OS-supported change notifications, this can be |
|
|
1153 | resource-intensive. |
|
|
1154 | |
|
|
1155 | At the time of this writing, no specific OS backends are implemented, but |
|
|
1156 | if demand increases, at least a kqueue and inotify backend will be added. |
|
|
1157 | |
|
|
1158 | =over 4 |
|
|
1159 | |
|
|
1160 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
|
|
1161 | |
|
|
1162 | =item ev_stat_set (ev_stat *, const char *path, ev_tstamp interval) |
|
|
1163 | |
|
|
1164 | Configures the watcher to wait for status changes of the given |
|
|
1165 | C<path>. The C<interval> is a hint on how quickly a change is expected to |
|
|
1166 | be detected and should normally be specified as C<0> to let libev choose |
|
|
1167 | a suitable value. The memory pointed to by C<path> must point to the same |
|
|
1168 | path for as long as the watcher is active. |
|
|
1169 | |
|
|
1170 | The callback will be receive C<EV_STAT> when a change was detected, |
|
|
1171 | relative to the attributes at the time the watcher was started (or the |
|
|
1172 | last change was detected). |
|
|
1173 | |
|
|
1174 | =item ev_stat_stat (ev_stat *) |
|
|
1175 | |
|
|
1176 | Updates the stat buffer immediately with new values. If you change the |
|
|
1177 | watched path in your callback, you could call this fucntion to avoid |
|
|
1178 | detecting this change (while introducing a race condition). Can also be |
|
|
1179 | useful simply to find out the new values. |
|
|
1180 | |
|
|
1181 | =item ev_statdata attr [read-only] |
|
|
1182 | |
|
|
1183 | The most-recently detected attributes of the file. Although the type is of |
|
|
1184 | C<ev_statdata>, this is usually the (or one of the) C<struct stat> types |
|
|
1185 | suitable for your system. If the C<st_nlink> member is C<0>, then there |
|
|
1186 | was some error while C<stat>ing the file. |
|
|
1187 | |
|
|
1188 | =item ev_statdata prev [read-only] |
|
|
1189 | |
|
|
1190 | The previous attributes of the file. The callback gets invoked whenever |
|
|
1191 | C<prev> != C<attr>. |
|
|
1192 | |
|
|
1193 | =item ev_tstamp interval [read-only] |
|
|
1194 | |
|
|
1195 | The specified interval. |
|
|
1196 | |
|
|
1197 | =item const char *path [read-only] |
|
|
1198 | |
|
|
1199 | The filesystem path that is being watched. |
|
|
1200 | |
|
|
1201 | =back |
|
|
1202 | |
|
|
1203 | Example: Watch C</etc/passwd> for attribute changes. |
|
|
1204 | |
|
|
1205 | static void |
|
|
1206 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
|
|
1207 | { |
|
|
1208 | /* /etc/passwd changed in some way */ |
|
|
1209 | if (w->attr.st_nlink) |
|
|
1210 | { |
|
|
1211 | printf ("passwd current size %ld\n", (long)w->attr.st_size); |
|
|
1212 | printf ("passwd current atime %ld\n", (long)w->attr.st_mtime); |
|
|
1213 | printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime); |
|
|
1214 | } |
|
|
1215 | else |
|
|
1216 | /* you shalt not abuse printf for puts */ |
|
|
1217 | puts ("wow, /etc/passwd is not there, expect problems. " |
|
|
1218 | "if this is windows, they already arrived\n"); |
|
|
1219 | } |
|
|
1220 | |
|
|
1221 | ... |
|
|
1222 | ev_stat passwd; |
|
|
1223 | |
|
|
1224 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
|
|
1225 | ev_stat_start (loop, &passwd); |
|
|
1226 | |
|
|
1227 | |
1050 | =head2 C<ev_idle> - when you've got nothing better to do |
1228 | =head2 C<ev_idle> - when you've got nothing better to do... |
1051 | |
1229 | |
1052 | Idle watchers trigger events when there are no other events are pending |
1230 | Idle watchers trigger events when there are no other events are pending |
1053 | (prepare, check and other idle watchers do not count). That is, as long |
1231 | (prepare, check and other idle watchers do not count). That is, as long |
1054 | as your process is busy handling sockets or timeouts (or even signals, |
1232 | as your process is busy handling sockets or timeouts (or even signals, |
1055 | imagine) it will not be triggered. But when your process is idle all idle |
1233 | imagine) it will not be triggered. But when your process is idle all idle |
… | |
… | |
1089 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1267 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1090 | ev_idle_init (idle_watcher, idle_cb); |
1268 | ev_idle_init (idle_watcher, idle_cb); |
1091 | ev_idle_start (loop, idle_cb); |
1269 | ev_idle_start (loop, idle_cb); |
1092 | |
1270 | |
1093 | |
1271 | |
1094 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop |
1272 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
1095 | |
1273 | |
1096 | Prepare and check watchers are usually (but not always) used in tandem: |
1274 | Prepare and check watchers are usually (but not always) used in tandem: |
1097 | prepare watchers get invoked before the process blocks and check watchers |
1275 | prepare watchers get invoked before the process blocks and check watchers |
1098 | afterwards. |
1276 | afterwards. |
1099 | |
1277 | |
|
|
1278 | You I<must not> call C<ev_loop> or similar functions that enter |
|
|
1279 | the current event loop from either C<ev_prepare> or C<ev_check> |
|
|
1280 | watchers. Other loops than the current one are fine, however. The |
|
|
1281 | rationale behind this is that you do not need to check for recursion in |
|
|
1282 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
|
|
1283 | C<ev_check> so if you have one watcher of each kind they will always be |
|
|
1284 | called in pairs bracketing the blocking call. |
|
|
1285 | |
1100 | Their main purpose is to integrate other event mechanisms into libev and |
1286 | Their main purpose is to integrate other event mechanisms into libev and |
1101 | their use is somewhat advanced. This could be used, for example, to track |
1287 | their use is somewhat advanced. This could be used, for example, to track |
1102 | variable changes, implement your own watchers, integrate net-snmp or a |
1288 | variable changes, implement your own watchers, integrate net-snmp or a |
1103 | coroutine library and lots more. |
1289 | coroutine library and lots more. They are also occasionally useful if |
|
|
1290 | you cache some data and want to flush it before blocking (for example, |
|
|
1291 | in X programs you might want to do an C<XFlush ()> in an C<ev_prepare> |
|
|
1292 | watcher). |
1104 | |
1293 | |
1105 | This is done by examining in each prepare call which file descriptors need |
1294 | This is done by examining in each prepare call which file descriptors need |
1106 | to be watched by the other library, registering C<ev_io> watchers for |
1295 | to be watched by the other library, registering C<ev_io> watchers for |
1107 | them and starting an C<ev_timer> watcher for any timeouts (many libraries |
1296 | them and starting an C<ev_timer> watcher for any timeouts (many libraries |
1108 | provide just this functionality). Then, in the check watcher you check for |
1297 | provide just this functionality). Then, in the check watcher you check for |
… | |
… | |
1130 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1319 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1131 | macros, but using them is utterly, utterly and completely pointless. |
1320 | macros, but using them is utterly, utterly and completely pointless. |
1132 | |
1321 | |
1133 | =back |
1322 | =back |
1134 | |
1323 | |
1135 | Example: *TODO*. |
1324 | Example: To include a library such as adns, you would add IO watchers |
|
|
1325 | and a timeout watcher in a prepare handler, as required by libadns, and |
|
|
1326 | in a check watcher, destroy them and call into libadns. What follows is |
|
|
1327 | pseudo-code only of course: |
1136 | |
1328 | |
|
|
1329 | static ev_io iow [nfd]; |
|
|
1330 | static ev_timer tw; |
1137 | |
1331 | |
|
|
1332 | static void |
|
|
1333 | io_cb (ev_loop *loop, ev_io *w, int revents) |
|
|
1334 | { |
|
|
1335 | // set the relevant poll flags |
|
|
1336 | // could also call adns_processreadable etc. here |
|
|
1337 | struct pollfd *fd = (struct pollfd *)w->data; |
|
|
1338 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1339 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1340 | } |
|
|
1341 | |
|
|
1342 | // create io watchers for each fd and a timer before blocking |
|
|
1343 | static void |
|
|
1344 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
|
|
1345 | { |
|
|
1346 | int timeout = 3600000;truct pollfd fds [nfd]; |
|
|
1347 | // actual code will need to loop here and realloc etc. |
|
|
1348 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
|
|
1349 | |
|
|
1350 | /* the callback is illegal, but won't be called as we stop during check */ |
|
|
1351 | ev_timer_init (&tw, 0, timeout * 1e-3); |
|
|
1352 | ev_timer_start (loop, &tw); |
|
|
1353 | |
|
|
1354 | // create on ev_io per pollfd |
|
|
1355 | for (int i = 0; i < nfd; ++i) |
|
|
1356 | { |
|
|
1357 | ev_io_init (iow + i, io_cb, fds [i].fd, |
|
|
1358 | ((fds [i].events & POLLIN ? EV_READ : 0) |
|
|
1359 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
|
|
1360 | |
|
|
1361 | fds [i].revents = 0; |
|
|
1362 | iow [i].data = fds + i; |
|
|
1363 | ev_io_start (loop, iow + i); |
|
|
1364 | } |
|
|
1365 | } |
|
|
1366 | |
|
|
1367 | // stop all watchers after blocking |
|
|
1368 | static void |
|
|
1369 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
|
|
1370 | { |
|
|
1371 | ev_timer_stop (loop, &tw); |
|
|
1372 | |
|
|
1373 | for (int i = 0; i < nfd; ++i) |
|
|
1374 | ev_io_stop (loop, iow + i); |
|
|
1375 | |
|
|
1376 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
1377 | } |
|
|
1378 | |
|
|
1379 | |
1138 | =head2 C<ev_embed> - when one backend isn't enough |
1380 | =head2 C<ev_embed> - when one backend isn't enough... |
1139 | |
1381 | |
1140 | This is a rather advanced watcher type that lets you embed one event loop |
1382 | This is a rather advanced watcher type that lets you embed one event loop |
1141 | into another (currently only C<ev_io> events are supported in the embedded |
1383 | into another (currently only C<ev_io> events are supported in the embedded |
1142 | loop, other types of watchers might be handled in a delayed or incorrect |
1384 | loop, other types of watchers might be handled in a delayed or incorrect |
1143 | fashion and must not be used). |
1385 | fashion and must not be used). |
… | |
… | |
1221 | |
1463 | |
1222 | Make a single, non-blocking sweep over the embedded loop. This works |
1464 | Make a single, non-blocking sweep over the embedded loop. This works |
1223 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
1465 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
1224 | apropriate way for embedded loops. |
1466 | apropriate way for embedded loops. |
1225 | |
1467 | |
|
|
1468 | =item struct ev_loop *loop [read-only] |
|
|
1469 | |
|
|
1470 | The embedded event loop. |
|
|
1471 | |
1226 | =back |
1472 | =back |
1227 | |
1473 | |
1228 | |
1474 | |
1229 | =head1 OTHER FUNCTIONS |
1475 | =head1 OTHER FUNCTIONS |
1230 | |
1476 | |
… | |
… | |
1392 | |
1638 | |
1393 | =item w->sweep () C<ev::embed> only |
1639 | =item w->sweep () C<ev::embed> only |
1394 | |
1640 | |
1395 | Invokes C<ev_embed_sweep>. |
1641 | Invokes C<ev_embed_sweep>. |
1396 | |
1642 | |
|
|
1643 | =item w->update () C<ev::stat> only |
|
|
1644 | |
|
|
1645 | Invokes C<ev_stat_stat>. |
|
|
1646 | |
1397 | =back |
1647 | =back |
1398 | |
1648 | |
1399 | =back |
1649 | =back |
1400 | |
1650 | |
1401 | Example: Define a class with an IO and idle watcher, start one of them in |
1651 | Example: Define a class with an IO and idle watcher, start one of them in |
… | |
… | |
1462 | ev_vars.h |
1712 | ev_vars.h |
1463 | ev_wrap.h |
1713 | ev_wrap.h |
1464 | |
1714 | |
1465 | ev_win32.c required on win32 platforms only |
1715 | ev_win32.c required on win32 platforms only |
1466 | |
1716 | |
1467 | ev_select.c only when select backend is enabled (which is is by default) |
1717 | ev_select.c only when select backend is enabled (which is by default) |
1468 | ev_poll.c only when poll backend is enabled (disabled by default) |
1718 | ev_poll.c only when poll backend is enabled (disabled by default) |
1469 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
1719 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
1470 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
1720 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
1471 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
1721 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
1472 | |
1722 | |
1473 | F<ev.c> includes the backend files directly when enabled, so you only need |
1723 | F<ev.c> includes the backend files directly when enabled, so you only need |
1474 | to compile a single file. |
1724 | to compile this single file. |
1475 | |
1725 | |
1476 | =head3 LIBEVENT COMPATIBILITY API |
1726 | =head3 LIBEVENT COMPATIBILITY API |
1477 | |
1727 | |
1478 | To include the libevent compatibility API, also include: |
1728 | To include the libevent compatibility API, also include: |
1479 | |
1729 | |
… | |
… | |
1492 | |
1742 | |
1493 | =head3 AUTOCONF SUPPORT |
1743 | =head3 AUTOCONF SUPPORT |
1494 | |
1744 | |
1495 | Instead of using C<EV_STANDALONE=1> and providing your config in |
1745 | Instead of using C<EV_STANDALONE=1> and providing your config in |
1496 | whatever way you want, you can also C<m4_include([libev.m4])> in your |
1746 | whatever way you want, you can also C<m4_include([libev.m4])> in your |
1497 | F<configure.ac> and leave C<EV_STANDALONE> off. F<ev.c> will then include |
1747 | F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then |
1498 | F<config.h> and configure itself accordingly. |
1748 | include F<config.h> and configure itself accordingly. |
1499 | |
1749 | |
1500 | For this of course you need the m4 file: |
1750 | For this of course you need the m4 file: |
1501 | |
1751 | |
1502 | libev.m4 |
1752 | libev.m4 |
1503 | |
1753 | |
… | |
… | |
1583 | otherwise another method will be used as fallback. This is the preferred |
1833 | otherwise another method will be used as fallback. This is the preferred |
1584 | backend for BSD and BSD-like systems, although on most BSDs kqueue only |
1834 | backend for BSD and BSD-like systems, although on most BSDs kqueue only |
1585 | supports some types of fds correctly (the only platform we found that |
1835 | supports some types of fds correctly (the only platform we found that |
1586 | supports ptys for example was NetBSD), so kqueue might be compiled in, but |
1836 | supports ptys for example was NetBSD), so kqueue might be compiled in, but |
1587 | not be used unless explicitly requested. The best way to use it is to find |
1837 | not be used unless explicitly requested. The best way to use it is to find |
1588 | out wether kqueue supports your type of fd properly and use an embedded |
1838 | out whether kqueue supports your type of fd properly and use an embedded |
1589 | kqueue loop. |
1839 | kqueue loop. |
1590 | |
1840 | |
1591 | =item EV_USE_PORT |
1841 | =item EV_USE_PORT |
1592 | |
1842 | |
1593 | If defined to be C<1>, libev will compile in support for the Solaris |
1843 | If defined to be C<1>, libev will compile in support for the Solaris |
… | |
… | |
1629 | will have the C<struct ev_loop *> as first argument, and you can create |
1879 | will have the C<struct ev_loop *> as first argument, and you can create |
1630 | additional independent event loops. Otherwise there will be no support |
1880 | additional independent event loops. Otherwise there will be no support |
1631 | for multiple event loops and there is no first event loop pointer |
1881 | for multiple event loops and there is no first event loop pointer |
1632 | argument. Instead, all functions act on the single default loop. |
1882 | argument. Instead, all functions act on the single default loop. |
1633 | |
1883 | |
1634 | =item EV_PERIODICS |
1884 | =item EV_PERIODIC_ENABLE |
1635 | |
1885 | |
1636 | If undefined or defined to be C<1>, then periodic timers are supported, |
1886 | If undefined or defined to be C<1>, then periodic timers are supported. If |
1637 | otherwise not. This saves a few kb of code. |
1887 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
1888 | code. |
|
|
1889 | |
|
|
1890 | =item EV_EMBED_ENABLE |
|
|
1891 | |
|
|
1892 | If undefined or defined to be C<1>, then embed watchers are supported. If |
|
|
1893 | defined to be C<0>, then they are not. |
|
|
1894 | |
|
|
1895 | =item EV_STAT_ENABLE |
|
|
1896 | |
|
|
1897 | If undefined or defined to be C<1>, then stat watchers are supported. If |
|
|
1898 | defined to be C<0>, then they are not. |
|
|
1899 | |
|
|
1900 | =item EV_MINIMAL |
|
|
1901 | |
|
|
1902 | If you need to shave off some kilobytes of code at the expense of some |
|
|
1903 | speed, define this symbol to C<1>. Currently only used for gcc to override |
|
|
1904 | some inlining decisions, saves roughly 30% codesize of amd64. |
1638 | |
1905 | |
1639 | =item EV_COMMON |
1906 | =item EV_COMMON |
1640 | |
1907 | |
1641 | By default, all watchers have a C<void *data> member. By redefining |
1908 | By default, all watchers have a C<void *data> member. By redefining |
1642 | this macro to a something else you can include more and other types of |
1909 | this macro to a something else you can include more and other types of |
… | |
… | |
1647 | |
1914 | |
1648 | #define EV_COMMON \ |
1915 | #define EV_COMMON \ |
1649 | SV *self; /* contains this struct */ \ |
1916 | SV *self; /* contains this struct */ \ |
1650 | SV *cb_sv, *fh /* note no trailing ";" */ |
1917 | SV *cb_sv, *fh /* note no trailing ";" */ |
1651 | |
1918 | |
1652 | =item EV_CB_DECLARE(type) |
1919 | =item EV_CB_DECLARE (type) |
1653 | |
1920 | |
1654 | =item EV_CB_INVOKE(watcher,revents) |
1921 | =item EV_CB_INVOKE (watcher, revents) |
1655 | |
1922 | |
1656 | =item ev_set_cb(ev,cb) |
1923 | =item ev_set_cb (ev, cb) |
1657 | |
1924 | |
1658 | Can be used to change the callback member declaration in each watcher, |
1925 | Can be used to change the callback member declaration in each watcher, |
1659 | and the way callbacks are invoked and set. Must expand to a struct member |
1926 | and the way callbacks are invoked and set. Must expand to a struct member |
1660 | definition and a statement, respectively. See the F<ev.v> header file for |
1927 | definition and a statement, respectively. See the F<ev.v> header file for |
1661 | their default definitions. One possible use for overriding these is to |
1928 | their default definitions. One possible use for overriding these is to |
1662 | avoid the ev_loop pointer as first argument in all cases, or to use method |
1929 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
1663 | calls instead of plain function calls in C++. |
1930 | method calls instead of plain function calls in C++. |
1664 | |
1931 | |
1665 | =head2 EXAMPLES |
1932 | =head2 EXAMPLES |
1666 | |
1933 | |
1667 | For a real-world example of a program the includes libev |
1934 | For a real-world example of a program the includes libev |
1668 | verbatim, you can have a look at the EV perl module |
1935 | verbatim, you can have a look at the EV perl module |
… | |
… | |
1673 | file. |
1940 | file. |
1674 | |
1941 | |
1675 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
1942 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
1676 | that everybody includes and which overrides some autoconf choices: |
1943 | that everybody includes and which overrides some autoconf choices: |
1677 | |
1944 | |
1678 | #define EV_USE_POLL 0 |
1945 | #define EV_USE_POLL 0 |
1679 | #define EV_MULTIPLICITY 0 |
1946 | #define EV_MULTIPLICITY 0 |
1680 | #define EV_PERIODICS 0 |
1947 | #define EV_PERIODICS 0 |
1681 | #define EV_CONFIG_H <config.h> |
1948 | #define EV_CONFIG_H <config.h> |
1682 | |
1949 | |
1683 | #include "ev++.h" |
1950 | #include "ev++.h" |
1684 | |
1951 | |
1685 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
1952 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
1686 | |
1953 | |
1687 | #include "rxvttoolkit.h" |
1954 | #include "ev_cpp.h" |
1688 | |
|
|
1689 | /* darwin has problems with its header files in C++, requiring this namespace juggling */ |
|
|
1690 | using namespace ev; |
|
|
1691 | |
|
|
1692 | #include "ev.c" |
1955 | #include "ev.c" |
|
|
1956 | |
|
|
1957 | |
|
|
1958 | =head1 COMPLEXITIES |
|
|
1959 | |
|
|
1960 | In this section the complexities of (many of) the algorithms used inside |
|
|
1961 | libev will be explained. For complexity discussions about backends see the |
|
|
1962 | documentation for C<ev_default_init>. |
|
|
1963 | |
|
|
1964 | =over 4 |
|
|
1965 | |
|
|
1966 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
|
|
1967 | |
|
|
1968 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
|
|
1969 | |
|
|
1970 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
|
|
1971 | |
|
|
1972 | =item Stopping check/prepare/idle watchers: O(1) |
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1973 | |
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1974 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16)) |
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1975 | |
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1976 | =item Finding the next timer per loop iteration: O(1) |
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1977 | |
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1978 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
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1979 | |
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1980 | =item Activating one watcher: O(1) |
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1981 | |
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1982 | =back |
1693 | |
1983 | |
1694 | |
1984 | |
1695 | =head1 AUTHOR |
1985 | =head1 AUTHOR |
1696 | |
1986 | |
1697 | Marc Lehmann <libev@schmorp.de>. |
1987 | Marc Lehmann <libev@schmorp.de>. |