… | |
… | |
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: |
… | |
… | |
576 | with the error from read() or write(). This will not work in multithreaded |
577 | with the error from read() or write(). This will not work in multithreaded |
577 | programs, though, so beware. |
578 | programs, though, so beware. |
578 | |
579 | |
579 | =back |
580 | =back |
580 | |
581 | |
581 | =head2 SUMMARY OF GENERIC WATCHER FUNCTIONS |
582 | =head2 GENERIC WATCHER FUNCTIONS |
582 | |
583 | |
583 | In the following description, C<TYPE> stands for the watcher type, |
584 | 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. |
585 | e.g. C<timer> for C<ev_timer> watchers and C<io> for C<ev_io> watchers. |
585 | |
586 | |
586 | =over 4 |
587 | =over 4 |
… | |
… | |
595 | which rolls both calls into one. |
596 | which rolls both calls into one. |
596 | |
597 | |
597 | You can reinitialise a watcher at any time as long as it has been stopped |
598 | 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. |
599 | (or never started) and there are no pending events outstanding. |
599 | |
600 | |
600 | The callbakc is always of type C<void (*)(ev_loop *loop, ev_TYPE *watcher, |
601 | The callback is always of type C<void (*)(ev_loop *loop, ev_TYPE *watcher, |
601 | int revents)>. |
602 | int revents)>. |
602 | |
603 | |
603 | =item C<ev_TYPE_set> (ev_TYPE *, [args]) |
604 | =item C<ev_TYPE_set> (ev_TYPE *, [args]) |
604 | |
605 | |
605 | This macro initialises the type-specific parts of a watcher. You need to |
606 | This macro initialises the type-specific parts of a watcher. You need to |
… | |
… | |
691 | |
692 | |
692 | This section describes each watcher in detail, but will not repeat |
693 | This section describes each watcher in detail, but will not repeat |
693 | information given in the last section. |
694 | information given in the last section. |
694 | |
695 | |
695 | |
696 | |
696 | =head2 C<ev_io> - is this file descriptor readable or writable |
697 | =head2 C<ev_io> - is this file descriptor readable or writable? |
697 | |
698 | |
698 | I/O watchers check whether a file descriptor is readable or writable |
699 | I/O watchers check whether a file descriptor is readable or writable |
699 | in each iteration of the event loop (This behaviour is called |
700 | in each iteration of the event loop, or, more precisely, when reading |
700 | level-triggering because you keep receiving events as long as the |
701 | 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 |
702 | some data. This behaviour is called level-triggering because you keep |
702 | act on the event and neither want to receive future events). |
703 | receiving events as long as the condition persists. Remember you can stop |
|
|
704 | the watcher if you don't want to act on the event and neither want to |
|
|
705 | receive future events. |
703 | |
706 | |
704 | In general you can register as many read and/or write event watchers per |
707 | 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 |
708 | 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 |
709 | descriptors to non-blocking mode is also usually a good idea (but not |
707 | required if you know what you are doing). |
710 | required if you know what you are doing). |
708 | |
711 | |
709 | You have to be careful with dup'ed file descriptors, though. Some backends |
712 | 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 |
713 | (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 |
714 | 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 |
715 | to the same underlying file/socket/etc. description (that is, they share |
713 | the same underlying "file open"). |
716 | the same underlying "file open"). |
714 | |
717 | |
715 | If you must do this, then force the use of a known-to-be-good backend |
718 | 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 |
719 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
717 | C<EVBACKEND_POLL>). |
720 | C<EVBACKEND_POLL>). |
718 | |
721 | |
|
|
722 | Another thing you have to watch out for is that it is quite easy to |
|
|
723 | receive "spurious" readyness notifications, that is your callback might |
|
|
724 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
|
|
725 | because there is no data. Not only are some backends known to create a |
|
|
726 | lot of those (for example solaris ports), it is very easy to get into |
|
|
727 | this situation even with a relatively standard program structure. Thus |
|
|
728 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
|
|
729 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
|
|
730 | |
|
|
731 | If you cannot run the fd in non-blocking mode (for example you should not |
|
|
732 | play around with an Xlib connection), then you have to seperately re-test |
|
|
733 | wether a file descriptor is really ready with a known-to-be good interface |
|
|
734 | such as poll (fortunately in our Xlib example, Xlib already does this on |
|
|
735 | its own, so its quite safe to use). |
|
|
736 | |
719 | =over 4 |
737 | =over 4 |
720 | |
738 | |
721 | =item ev_io_init (ev_io *, callback, int fd, int events) |
739 | =item ev_io_init (ev_io *, callback, int fd, int events) |
722 | |
740 | |
723 | =item ev_io_set (ev_io *, int fd, int events) |
741 | =item ev_io_set (ev_io *, int fd, int events) |
724 | |
742 | |
725 | Configures an C<ev_io> watcher. The fd is the file descriptor to rceeive |
743 | 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 | |
744 | rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or |
727 | EV_WRITE> to receive the given events. |
745 | C<EV_READ | EV_WRITE> to receive the given events. |
728 | |
|
|
729 | Please note that most of the more scalable backend mechanisms (for example |
|
|
730 | epoll and solaris ports) can result in spurious readyness notifications |
|
|
731 | for file descriptors, so you practically need to use non-blocking I/O (and |
|
|
732 | treat callback invocation as hint only), or retest separately with a safe |
|
|
733 | interface before doing I/O (XLib can do this), or force the use of either |
|
|
734 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>, which don't suffer from this |
|
|
735 | problem. Also note that it is quite easy to have your callback invoked |
|
|
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 | |
746 | |
740 | =back |
747 | =back |
741 | |
748 | |
742 | Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well |
749 | 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 |
750 | 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); |
763 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
757 | ev_io_start (loop, &stdin_readable); |
764 | ev_io_start (loop, &stdin_readable); |
758 | ev_loop (loop, 0); |
765 | ev_loop (loop, 0); |
759 | |
766 | |
760 | |
767 | |
761 | =head2 C<ev_timer> - relative and optionally recurring timeouts |
768 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
762 | |
769 | |
763 | Timer watchers are simple relative timers that generate an event after a |
770 | Timer watchers are simple relative timers that generate an event after a |
764 | given time, and optionally repeating in regular intervals after that. |
771 | given time, and optionally repeating in regular intervals after that. |
765 | |
772 | |
766 | The timers are based on real time, that is, if you register an event that |
773 | The timers are based on real time, that is, if you register an event that |
… | |
… | |
848 | // and in some piece of code that gets executed on any "activity": |
855 | // and in some piece of code that gets executed on any "activity": |
849 | // reset the timeout to start ticking again at 10 seconds |
856 | // reset the timeout to start ticking again at 10 seconds |
850 | ev_timer_again (&mytimer); |
857 | ev_timer_again (&mytimer); |
851 | |
858 | |
852 | |
859 | |
853 | =head2 C<ev_periodic> - to cron or not to cron |
860 | =head2 C<ev_periodic> - to cron or not to cron? |
854 | |
861 | |
855 | Periodic watchers are also timers of a kind, but they are very versatile |
862 | Periodic watchers are also timers of a kind, but they are very versatile |
856 | (and unfortunately a bit complex). |
863 | (and unfortunately a bit complex). |
857 | |
864 | |
858 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
865 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
… | |
… | |
986 | ev_periodic_init (&hourly_tick, clock_cb, |
993 | ev_periodic_init (&hourly_tick, clock_cb, |
987 | fmod (ev_now (loop), 3600.), 3600., 0); |
994 | fmod (ev_now (loop), 3600.), 3600., 0); |
988 | ev_periodic_start (loop, &hourly_tick); |
995 | ev_periodic_start (loop, &hourly_tick); |
989 | |
996 | |
990 | |
997 | |
991 | =head2 C<ev_signal> - signal me when a signal gets signalled |
998 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
992 | |
999 | |
993 | Signal watchers will trigger an event when the process receives a specific |
1000 | 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 |
1001 | 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 |
1002 | will try it's best to deliver signals synchronously, i.e. as part of the |
996 | normal event processing, like any other event. |
1003 | normal event processing, like any other event. |
… | |
… | |
1012 | of the C<SIGxxx> constants). |
1019 | of the C<SIGxxx> constants). |
1013 | |
1020 | |
1014 | =back |
1021 | =back |
1015 | |
1022 | |
1016 | |
1023 | |
1017 | =head2 C<ev_child> - wait for pid status changes |
1024 | =head2 C<ev_child> - watch out for process status changes |
1018 | |
1025 | |
1019 | Child watchers trigger when your process receives a SIGCHLD in response to |
1026 | 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). |
1027 | some child status changes (most typically when a child of yours dies). |
1021 | |
1028 | |
1022 | =over 4 |
1029 | =over 4 |
… | |
… | |
1045 | struct ev_signal signal_watcher; |
1052 | struct ev_signal signal_watcher; |
1046 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1053 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1047 | ev_signal_start (loop, &sigint_cb); |
1054 | ev_signal_start (loop, &sigint_cb); |
1048 | |
1055 | |
1049 | |
1056 | |
1050 | =head2 C<ev_idle> - when you've got nothing better to do |
1057 | =head2 C<ev_idle> - when you've got nothing better to do... |
1051 | |
1058 | |
1052 | Idle watchers trigger events when there are no other events are pending |
1059 | 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 |
1060 | (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, |
1061 | 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 |
1062 | 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)); |
1096 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1090 | ev_idle_init (idle_watcher, idle_cb); |
1097 | ev_idle_init (idle_watcher, idle_cb); |
1091 | ev_idle_start (loop, idle_cb); |
1098 | ev_idle_start (loop, idle_cb); |
1092 | |
1099 | |
1093 | |
1100 | |
1094 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop |
1101 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
1095 | |
1102 | |
1096 | Prepare and check watchers are usually (but not always) used in tandem: |
1103 | Prepare and check watchers are usually (but not always) used in tandem: |
1097 | prepare watchers get invoked before the process blocks and check watchers |
1104 | prepare watchers get invoked before the process blocks and check watchers |
1098 | afterwards. |
1105 | afterwards. |
1099 | |
1106 | |
|
|
1107 | You I<must not> call C<ev_loop> or similar functions that enter |
|
|
1108 | the current event loop from either C<ev_prepare> or C<ev_check> |
|
|
1109 | watchers. Other loops than the current one are fine, however. The |
|
|
1110 | rationale behind this is that you do not need to check for recursion in |
|
|
1111 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
|
|
1112 | C<ev_check> so if you have one watcher of each kind they will always be |
|
|
1113 | called in pairs bracketing the blocking call. |
|
|
1114 | |
1100 | Their main purpose is to integrate other event mechanisms into libev and |
1115 | 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 |
1116 | 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 |
1117 | variable changes, implement your own watchers, integrate net-snmp or a |
1103 | coroutine library and lots more. |
1118 | coroutine library and lots more. They are also occasionally useful if |
|
|
1119 | you cache some data and want to flush it before blocking (for example, |
|
|
1120 | in X programs you might want to do an C<XFlush ()> in an C<ev_prepare> |
|
|
1121 | watcher). |
1104 | |
1122 | |
1105 | This is done by examining in each prepare call which file descriptors need |
1123 | 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 |
1124 | 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 |
1125 | 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 |
1126 | 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> |
1148 | 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. |
1149 | macros, but using them is utterly, utterly and completely pointless. |
1132 | |
1150 | |
1133 | =back |
1151 | =back |
1134 | |
1152 | |
1135 | Example: *TODO*. |
1153 | Example: To include a library such as adns, you would add IO watchers |
|
|
1154 | and a timeout watcher in a prepare handler, as required by libadns, and |
|
|
1155 | in a check watcher, destroy them and call into libadns. What follows is |
|
|
1156 | pseudo-code only of course: |
1136 | |
1157 | |
|
|
1158 | static ev_io iow [nfd]; |
|
|
1159 | static ev_timer tw; |
1137 | |
1160 | |
|
|
1161 | static void |
|
|
1162 | io_cb (ev_loop *loop, ev_io *w, int revents) |
|
|
1163 | { |
|
|
1164 | // set the relevant poll flags |
|
|
1165 | // could also call adns_processreadable etc. here |
|
|
1166 | struct pollfd *fd = (struct pollfd *)w->data; |
|
|
1167 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1168 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1169 | } |
|
|
1170 | |
|
|
1171 | // create io watchers for each fd and a timer before blocking |
|
|
1172 | static void |
|
|
1173 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
|
|
1174 | { |
|
|
1175 | int timeout = 3600000;truct pollfd fds [nfd]; |
|
|
1176 | // actual code will need to loop here and realloc etc. |
|
|
1177 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
|
|
1178 | |
|
|
1179 | /* the callback is illegal, but won't be called as we stop during check */ |
|
|
1180 | ev_timer_init (&tw, 0, timeout * 1e-3); |
|
|
1181 | ev_timer_start (loop, &tw); |
|
|
1182 | |
|
|
1183 | // create on ev_io per pollfd |
|
|
1184 | for (int i = 0; i < nfd; ++i) |
|
|
1185 | { |
|
|
1186 | ev_io_init (iow + i, io_cb, fds [i].fd, |
|
|
1187 | ((fds [i].events & POLLIN ? EV_READ : 0) |
|
|
1188 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
|
|
1189 | |
|
|
1190 | fds [i].revents = 0; |
|
|
1191 | iow [i].data = fds + i; |
|
|
1192 | ev_io_start (loop, iow + i); |
|
|
1193 | } |
|
|
1194 | } |
|
|
1195 | |
|
|
1196 | // stop all watchers after blocking |
|
|
1197 | static void |
|
|
1198 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
|
|
1199 | { |
|
|
1200 | ev_timer_stop (loop, &tw); |
|
|
1201 | |
|
|
1202 | for (int i = 0; i < nfd; ++i) |
|
|
1203 | ev_io_stop (loop, iow + i); |
|
|
1204 | |
|
|
1205 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
1206 | } |
|
|
1207 | |
|
|
1208 | |
1138 | =head2 C<ev_embed> - when one backend isn't enough |
1209 | =head2 C<ev_embed> - when one backend isn't enough... |
1139 | |
1210 | |
1140 | This is a rather advanced watcher type that lets you embed one event loop |
1211 | 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 |
1212 | 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 |
1213 | loop, other types of watchers might be handled in a delayed or incorrect |
1143 | fashion and must not be used). |
1214 | fashion and must not be used). |
… | |
… | |
1414 | idle (this, &myclass::idle_cb) |
1485 | idle (this, &myclass::idle_cb) |
1415 | { |
1486 | { |
1416 | io.start (fd, ev::READ); |
1487 | io.start (fd, ev::READ); |
1417 | } |
1488 | } |
1418 | |
1489 | |
|
|
1490 | =head1 EMBEDDING |
|
|
1491 | |
|
|
1492 | Libev can (and often is) directly embedded into host |
|
|
1493 | applications. Examples of applications that embed it include the Deliantra |
|
|
1494 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
|
|
1495 | and rxvt-unicode. |
|
|
1496 | |
|
|
1497 | The goal is to enable you to just copy the neecssary files into your |
|
|
1498 | source directory without having to change even a single line in them, so |
|
|
1499 | you can easily upgrade by simply copying (or having a checked-out copy of |
|
|
1500 | libev somewhere in your source tree). |
|
|
1501 | |
|
|
1502 | =head2 FILESETS |
|
|
1503 | |
|
|
1504 | Depending on what features you need you need to include one or more sets of files |
|
|
1505 | in your app. |
|
|
1506 | |
|
|
1507 | =head3 CORE EVENT LOOP |
|
|
1508 | |
|
|
1509 | To include only the libev core (all the C<ev_*> functions), with manual |
|
|
1510 | configuration (no autoconf): |
|
|
1511 | |
|
|
1512 | #define EV_STANDALONE 1 |
|
|
1513 | #include "ev.c" |
|
|
1514 | |
|
|
1515 | This will automatically include F<ev.h>, too, and should be done in a |
|
|
1516 | single C source file only to provide the function implementations. To use |
|
|
1517 | it, do the same for F<ev.h> in all files wishing to use this API (best |
|
|
1518 | done by writing a wrapper around F<ev.h> that you can include instead and |
|
|
1519 | where you can put other configuration options): |
|
|
1520 | |
|
|
1521 | #define EV_STANDALONE 1 |
|
|
1522 | #include "ev.h" |
|
|
1523 | |
|
|
1524 | Both header files and implementation files can be compiled with a C++ |
|
|
1525 | compiler (at least, thats a stated goal, and breakage will be treated |
|
|
1526 | as a bug). |
|
|
1527 | |
|
|
1528 | You need the following files in your source tree, or in a directory |
|
|
1529 | in your include path (e.g. in libev/ when using -Ilibev): |
|
|
1530 | |
|
|
1531 | ev.h |
|
|
1532 | ev.c |
|
|
1533 | ev_vars.h |
|
|
1534 | ev_wrap.h |
|
|
1535 | |
|
|
1536 | ev_win32.c required on win32 platforms only |
|
|
1537 | |
|
|
1538 | ev_select.c only when select backend is enabled (which is by default) |
|
|
1539 | ev_poll.c only when poll backend is enabled (disabled by default) |
|
|
1540 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
|
|
1541 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
|
|
1542 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
|
|
1543 | |
|
|
1544 | F<ev.c> includes the backend files directly when enabled, so you only need |
|
|
1545 | to compile this single file. |
|
|
1546 | |
|
|
1547 | =head3 LIBEVENT COMPATIBILITY API |
|
|
1548 | |
|
|
1549 | To include the libevent compatibility API, also include: |
|
|
1550 | |
|
|
1551 | #include "event.c" |
|
|
1552 | |
|
|
1553 | in the file including F<ev.c>, and: |
|
|
1554 | |
|
|
1555 | #include "event.h" |
|
|
1556 | |
|
|
1557 | in the files that want to use the libevent API. This also includes F<ev.h>. |
|
|
1558 | |
|
|
1559 | You need the following additional files for this: |
|
|
1560 | |
|
|
1561 | event.h |
|
|
1562 | event.c |
|
|
1563 | |
|
|
1564 | =head3 AUTOCONF SUPPORT |
|
|
1565 | |
|
|
1566 | Instead of using C<EV_STANDALONE=1> and providing your config in |
|
|
1567 | whatever way you want, you can also C<m4_include([libev.m4])> in your |
|
|
1568 | F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then |
|
|
1569 | include F<config.h> and configure itself accordingly. |
|
|
1570 | |
|
|
1571 | For this of course you need the m4 file: |
|
|
1572 | |
|
|
1573 | libev.m4 |
|
|
1574 | |
|
|
1575 | =head2 PREPROCESSOR SYMBOLS/MACROS |
|
|
1576 | |
|
|
1577 | Libev can be configured via a variety of preprocessor symbols you have to define |
|
|
1578 | before including any of its files. The default is not to build for multiplicity |
|
|
1579 | and only include the select backend. |
|
|
1580 | |
|
|
1581 | =over 4 |
|
|
1582 | |
|
|
1583 | =item EV_STANDALONE |
|
|
1584 | |
|
|
1585 | Must always be C<1> if you do not use autoconf configuration, which |
|
|
1586 | keeps libev from including F<config.h>, and it also defines dummy |
|
|
1587 | implementations for some libevent functions (such as logging, which is not |
|
|
1588 | supported). It will also not define any of the structs usually found in |
|
|
1589 | F<event.h> that are not directly supported by the libev core alone. |
|
|
1590 | |
|
|
1591 | =item EV_USE_MONOTONIC |
|
|
1592 | |
|
|
1593 | If defined to be C<1>, libev will try to detect the availability of the |
|
|
1594 | monotonic clock option at both compiletime and runtime. Otherwise no use |
|
|
1595 | of the monotonic clock option will be attempted. If you enable this, you |
|
|
1596 | usually have to link against librt or something similar. Enabling it when |
|
|
1597 | the functionality isn't available is safe, though, althoguh you have |
|
|
1598 | to make sure you link against any libraries where the C<clock_gettime> |
|
|
1599 | function is hiding in (often F<-lrt>). |
|
|
1600 | |
|
|
1601 | =item EV_USE_REALTIME |
|
|
1602 | |
|
|
1603 | If defined to be C<1>, libev will try to detect the availability of the |
|
|
1604 | realtime clock option at compiletime (and assume its availability at |
|
|
1605 | runtime if successful). Otherwise no use of the realtime clock option will |
|
|
1606 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
|
|
1607 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries |
|
|
1608 | in the description of C<EV_USE_MONOTONIC>, though. |
|
|
1609 | |
|
|
1610 | =item EV_USE_SELECT |
|
|
1611 | |
|
|
1612 | If undefined or defined to be C<1>, libev will compile in support for the |
|
|
1613 | C<select>(2) backend. No attempt at autodetection will be done: if no |
|
|
1614 | other method takes over, select will be it. Otherwise the select backend |
|
|
1615 | will not be compiled in. |
|
|
1616 | |
|
|
1617 | =item EV_SELECT_USE_FD_SET |
|
|
1618 | |
|
|
1619 | If defined to C<1>, then the select backend will use the system C<fd_set> |
|
|
1620 | structure. This is useful if libev doesn't compile due to a missing |
|
|
1621 | C<NFDBITS> or C<fd_mask> definition or it misguesses the bitset layout on |
|
|
1622 | exotic systems. This usually limits the range of file descriptors to some |
|
|
1623 | low limit such as 1024 or might have other limitations (winsocket only |
|
|
1624 | allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might |
|
|
1625 | influence the size of the C<fd_set> used. |
|
|
1626 | |
|
|
1627 | =item EV_SELECT_IS_WINSOCKET |
|
|
1628 | |
|
|
1629 | When defined to C<1>, the select backend will assume that |
|
|
1630 | select/socket/connect etc. don't understand file descriptors but |
|
|
1631 | wants osf handles on win32 (this is the case when the select to |
|
|
1632 | be used is the winsock select). This means that it will call |
|
|
1633 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
|
|
1634 | it is assumed that all these functions actually work on fds, even |
|
|
1635 | on win32. Should not be defined on non-win32 platforms. |
|
|
1636 | |
|
|
1637 | =item EV_USE_POLL |
|
|
1638 | |
|
|
1639 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
|
|
1640 | backend. Otherwise it will be enabled on non-win32 platforms. It |
|
|
1641 | takes precedence over select. |
|
|
1642 | |
|
|
1643 | =item EV_USE_EPOLL |
|
|
1644 | |
|
|
1645 | If defined to be C<1>, libev will compile in support for the Linux |
|
|
1646 | C<epoll>(7) backend. Its availability will be detected at runtime, |
|
|
1647 | otherwise another method will be used as fallback. This is the |
|
|
1648 | preferred backend for GNU/Linux systems. |
|
|
1649 | |
|
|
1650 | =item EV_USE_KQUEUE |
|
|
1651 | |
|
|
1652 | If defined to be C<1>, libev will compile in support for the BSD style |
|
|
1653 | C<kqueue>(2) backend. Its actual availability will be detected at runtime, |
|
|
1654 | otherwise another method will be used as fallback. This is the preferred |
|
|
1655 | backend for BSD and BSD-like systems, although on most BSDs kqueue only |
|
|
1656 | supports some types of fds correctly (the only platform we found that |
|
|
1657 | supports ptys for example was NetBSD), so kqueue might be compiled in, but |
|
|
1658 | not be used unless explicitly requested. The best way to use it is to find |
|
|
1659 | out whether kqueue supports your type of fd properly and use an embedded |
|
|
1660 | kqueue loop. |
|
|
1661 | |
|
|
1662 | =item EV_USE_PORT |
|
|
1663 | |
|
|
1664 | If defined to be C<1>, libev will compile in support for the Solaris |
|
|
1665 | 10 port style backend. Its availability will be detected at runtime, |
|
|
1666 | otherwise another method will be used as fallback. This is the preferred |
|
|
1667 | backend for Solaris 10 systems. |
|
|
1668 | |
|
|
1669 | =item EV_USE_DEVPOLL |
|
|
1670 | |
|
|
1671 | reserved for future expansion, works like the USE symbols above. |
|
|
1672 | |
|
|
1673 | =item EV_H |
|
|
1674 | |
|
|
1675 | The name of the F<ev.h> header file used to include it. The default if |
|
|
1676 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
|
|
1677 | can be used to virtually rename the F<ev.h> header file in case of conflicts. |
|
|
1678 | |
|
|
1679 | =item EV_CONFIG_H |
|
|
1680 | |
|
|
1681 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
|
|
1682 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
|
|
1683 | C<EV_H>, above. |
|
|
1684 | |
|
|
1685 | =item EV_EVENT_H |
|
|
1686 | |
|
|
1687 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
|
|
1688 | of how the F<event.h> header can be found. |
|
|
1689 | |
|
|
1690 | =item EV_PROTOTYPES |
|
|
1691 | |
|
|
1692 | If defined to be C<0>, then F<ev.h> will not define any function |
|
|
1693 | prototypes, but still define all the structs and other symbols. This is |
|
|
1694 | occasionally useful if you want to provide your own wrapper functions |
|
|
1695 | around libev functions. |
|
|
1696 | |
|
|
1697 | =item EV_MULTIPLICITY |
|
|
1698 | |
|
|
1699 | If undefined or defined to C<1>, then all event-loop-specific functions |
|
|
1700 | will have the C<struct ev_loop *> as first argument, and you can create |
|
|
1701 | additional independent event loops. Otherwise there will be no support |
|
|
1702 | for multiple event loops and there is no first event loop pointer |
|
|
1703 | argument. Instead, all functions act on the single default loop. |
|
|
1704 | |
|
|
1705 | =item EV_PERIODICS |
|
|
1706 | |
|
|
1707 | If undefined or defined to be C<1>, then periodic timers are supported, |
|
|
1708 | otherwise not. This saves a few kb of code. |
|
|
1709 | |
|
|
1710 | =item EV_COMMON |
|
|
1711 | |
|
|
1712 | By default, all watchers have a C<void *data> member. By redefining |
|
|
1713 | this macro to a something else you can include more and other types of |
|
|
1714 | members. You have to define it each time you include one of the files, |
|
|
1715 | though, and it must be identical each time. |
|
|
1716 | |
|
|
1717 | For example, the perl EV module uses something like this: |
|
|
1718 | |
|
|
1719 | #define EV_COMMON \ |
|
|
1720 | SV *self; /* contains this struct */ \ |
|
|
1721 | SV *cb_sv, *fh /* note no trailing ";" */ |
|
|
1722 | |
|
|
1723 | =item EV_CB_DECLARE (type) |
|
|
1724 | |
|
|
1725 | =item EV_CB_INVOKE (watcher, revents) |
|
|
1726 | |
|
|
1727 | =item ev_set_cb (ev, cb) |
|
|
1728 | |
|
|
1729 | Can be used to change the callback member declaration in each watcher, |
|
|
1730 | and the way callbacks are invoked and set. Must expand to a struct member |
|
|
1731 | definition and a statement, respectively. See the F<ev.v> header file for |
|
|
1732 | their default definitions. One possible use for overriding these is to |
|
|
1733 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
|
|
1734 | method calls instead of plain function calls in C++. |
|
|
1735 | |
|
|
1736 | =head2 EXAMPLES |
|
|
1737 | |
|
|
1738 | For a real-world example of a program the includes libev |
|
|
1739 | verbatim, you can have a look at the EV perl module |
|
|
1740 | (L<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
|
|
1741 | the F<libev/> subdirectory and includes them in the F<EV/EVAPI.h> (public |
|
|
1742 | interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file |
|
|
1743 | will be compiled. It is pretty complex because it provides its own header |
|
|
1744 | file. |
|
|
1745 | |
|
|
1746 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
|
|
1747 | that everybody includes and which overrides some autoconf choices: |
|
|
1748 | |
|
|
1749 | #define EV_USE_POLL 0 |
|
|
1750 | #define EV_MULTIPLICITY 0 |
|
|
1751 | #define EV_PERIODICS 0 |
|
|
1752 | #define EV_CONFIG_H <config.h> |
|
|
1753 | |
|
|
1754 | #include "ev++.h" |
|
|
1755 | |
|
|
1756 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
|
|
1757 | |
|
|
1758 | #include "ev_cpp.h" |
|
|
1759 | #include "ev.c" |
|
|
1760 | |
|
|
1761 | |
|
|
1762 | =head1 COMPLEXITIES |
|
|
1763 | |
|
|
1764 | In this section the complexities of (many of) the algorithms used inside |
|
|
1765 | libev will be explained. For complexity discussions about backends see the |
|
|
1766 | documentation for C<ev_default_init>. |
|
|
1767 | |
|
|
1768 | =over 4 |
|
|
1769 | |
|
|
1770 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
|
|
1771 | |
|
|
1772 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
|
|
1773 | |
|
|
1774 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
|
|
1775 | |
|
|
1776 | =item Stopping check/prepare/idle watchers: O(1) |
|
|
1777 | |
|
|
1778 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16)) |
|
|
1779 | |
|
|
1780 | =item Finding the next timer per loop iteration: O(1) |
|
|
1781 | |
|
|
1782 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
|
|
1783 | |
|
|
1784 | =item Activating one watcher: O(1) |
|
|
1785 | |
|
|
1786 | =back |
|
|
1787 | |
|
|
1788 | |
1419 | =head1 AUTHOR |
1789 | =head1 AUTHOR |
1420 | |
1790 | |
1421 | Marc Lehmann <libev@schmorp.de>. |
1791 | Marc Lehmann <libev@schmorp.de>. |
1422 | |
1792 | |