… | |
… | |
47 | |
47 | |
48 | return 0; |
48 | return 0; |
49 | } |
49 | } |
50 | |
50 | |
51 | =head1 DESCRIPTION |
51 | =head1 DESCRIPTION |
|
|
52 | |
|
|
53 | The newest version of this document is also available as a html-formatted |
|
|
54 | web page you might find easier to navigate when reading it for the first |
|
|
55 | time: L<http://cvs.schmorp.de/libev/ev.html>. |
52 | |
56 | |
53 | Libev is an event loop: you register interest in certain events (such as a |
57 | Libev is an event loop: you register interest in certain events (such as a |
54 | file descriptor being readable or a timeout occuring), and it will manage |
58 | file descriptor being readable or a timeout occuring), and it will manage |
55 | these event sources and provide your program with events. |
59 | these event sources and provide your program with events. |
56 | |
60 | |
… | |
… | |
113 | |
117 | |
114 | =item int ev_version_major () |
118 | =item int ev_version_major () |
115 | |
119 | |
116 | =item int ev_version_minor () |
120 | =item int ev_version_minor () |
117 | |
121 | |
118 | You can find out the major and minor version numbers of the library |
122 | You can find out the major and minor ABI version numbers of the library |
119 | you linked against by calling the functions C<ev_version_major> and |
123 | you linked against by calling the functions C<ev_version_major> and |
120 | C<ev_version_minor>. If you want, you can compare against the global |
124 | C<ev_version_minor>. If you want, you can compare against the global |
121 | symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the |
125 | symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the |
122 | version of the library your program was compiled against. |
126 | version of the library your program was compiled against. |
123 | |
127 | |
|
|
128 | These version numbers refer to the ABI version of the library, not the |
|
|
129 | release version. |
|
|
130 | |
124 | Usually, it's a good idea to terminate if the major versions mismatch, |
131 | Usually, it's a good idea to terminate if the major versions mismatch, |
125 | as this indicates an incompatible change. Minor versions are usually |
132 | as this indicates an incompatible change. Minor versions are usually |
126 | compatible to older versions, so a larger minor version alone is usually |
133 | compatible to older versions, so a larger minor version alone is usually |
127 | not a problem. |
134 | not a problem. |
128 | |
135 | |
129 | Example: Make sure we haven't accidentally been linked against the wrong |
136 | Example: Make sure we haven't accidentally been linked against the wrong |
130 | version. |
137 | version. |
… | |
… | |
482 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
489 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
483 | usually a better approach for this kind of thing. |
490 | usually a better approach for this kind of thing. |
484 | |
491 | |
485 | Here are the gory details of what C<ev_loop> does: |
492 | Here are the gory details of what C<ev_loop> does: |
486 | |
493 | |
|
|
494 | - Before the first iteration, call any pending watchers. |
487 | * If there are no active watchers (reference count is zero), return. |
495 | * If there are no active watchers (reference count is zero), return. |
488 | - Queue prepare watchers and then call all outstanding watchers. |
496 | - Queue all prepare watchers and then call all outstanding watchers. |
489 | - If we have been forked, recreate the kernel state. |
497 | - If we have been forked, recreate the kernel state. |
490 | - Update the kernel state with all outstanding changes. |
498 | - Update the kernel state with all outstanding changes. |
491 | - Update the "event loop time". |
499 | - Update the "event loop time". |
492 | - Calculate for how long to block. |
500 | - Calculate for how long to block. |
493 | - Block the process, waiting for any events. |
501 | - Block the process, waiting for any events. |
… | |
… | |
732 | =item bool ev_is_pending (ev_TYPE *watcher) |
740 | =item bool ev_is_pending (ev_TYPE *watcher) |
733 | |
741 | |
734 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
742 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
735 | events but its callback has not yet been invoked). As long as a watcher |
743 | events but its callback has not yet been invoked). As long as a watcher |
736 | is pending (but not active) you must not call an init function on it (but |
744 | is pending (but not active) you must not call an init function on it (but |
737 | C<ev_TYPE_set> is safe) and you must make sure the watcher is available to |
745 | C<ev_TYPE_set> is safe), you must not change its priority, and you must |
738 | libev (e.g. you cnanot C<free ()> it). |
746 | make sure the watcher is available to libev (e.g. you cannot C<free ()> |
|
|
747 | it). |
739 | |
748 | |
740 | =item callback ev_cb (ev_TYPE *watcher) |
749 | =item callback ev_cb (ev_TYPE *watcher) |
741 | |
750 | |
742 | Returns the callback currently set on the watcher. |
751 | Returns the callback currently set on the watcher. |
743 | |
752 | |
… | |
… | |
762 | watchers on the same event and make sure one is called first. |
771 | watchers on the same event and make sure one is called first. |
763 | |
772 | |
764 | If you need to suppress invocation when higher priority events are pending |
773 | If you need to suppress invocation when higher priority events are pending |
765 | you need to look at C<ev_idle> watchers, which provide this functionality. |
774 | you need to look at C<ev_idle> watchers, which provide this functionality. |
766 | |
775 | |
|
|
776 | You I<must not> change the priority of a watcher as long as it is active or |
|
|
777 | pending. |
|
|
778 | |
767 | The default priority used by watchers when no priority has been set is |
779 | The default priority used by watchers when no priority has been set is |
768 | always C<0>, which is supposed to not be too high and not be too low :). |
780 | always C<0>, which is supposed to not be too high and not be too low :). |
769 | |
781 | |
770 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
782 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
771 | fine, as long as you do not mind that the priority value you query might |
783 | fine, as long as you do not mind that the priority value you query might |
772 | or might not have been adjusted to be within valid range. |
784 | or might not have been adjusted to be within valid range. |
|
|
785 | |
|
|
786 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
|
|
787 | |
|
|
788 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
|
|
789 | C<loop> nor C<revents> need to be valid as long as the watcher callback |
|
|
790 | can deal with that fact. |
|
|
791 | |
|
|
792 | =item int ev_clear_pending (loop, ev_TYPE *watcher) |
|
|
793 | |
|
|
794 | If the watcher is pending, this function returns clears its pending status |
|
|
795 | and returns its C<revents> bitset (as if its callback was invoked). If the |
|
|
796 | watcher isn't pending it does nothing and returns C<0>. |
773 | |
797 | |
774 | =back |
798 | =back |
775 | |
799 | |
776 | |
800 | |
777 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
801 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
… | |
… | |
887 | play around with an Xlib connection), then you have to seperately re-test |
911 | play around with an Xlib connection), then you have to seperately re-test |
888 | whether a file descriptor is really ready with a known-to-be good interface |
912 | whether a file descriptor is really ready with a known-to-be good interface |
889 | such as poll (fortunately in our Xlib example, Xlib already does this on |
913 | such as poll (fortunately in our Xlib example, Xlib already does this on |
890 | its own, so its quite safe to use). |
914 | its own, so its quite safe to use). |
891 | |
915 | |
|
|
916 | =head3 The special problem of disappearing file descriptors |
|
|
917 | |
|
|
918 | Some backends (e.g kqueue, epoll) need to be told about closing a file |
|
|
919 | descriptor (either by calling C<close> explicitly or by any other means, |
|
|
920 | such as C<dup>). The reason is that you register interest in some file |
|
|
921 | descriptor, but when it goes away, the operating system will silently drop |
|
|
922 | this interest. If another file descriptor with the same number then is |
|
|
923 | registered with libev, there is no efficient way to see that this is, in |
|
|
924 | fact, a different file descriptor. |
|
|
925 | |
|
|
926 | To avoid having to explicitly tell libev about such cases, libev follows |
|
|
927 | the following policy: Each time C<ev_io_set> is being called, libev |
|
|
928 | will assume that this is potentially a new file descriptor, otherwise |
|
|
929 | it is assumed that the file descriptor stays the same. That means that |
|
|
930 | you I<have> to call C<ev_io_set> (or C<ev_io_init>) when you change the |
|
|
931 | descriptor even if the file descriptor number itself did not change. |
|
|
932 | |
|
|
933 | This is how one would do it normally anyway, the important point is that |
|
|
934 | the libev application should not optimise around libev but should leave |
|
|
935 | optimisations to libev. |
|
|
936 | |
|
|
937 | |
|
|
938 | =head3 Watcher-Specific Functions |
|
|
939 | |
892 | =over 4 |
940 | =over 4 |
893 | |
941 | |
894 | =item ev_io_init (ev_io *, callback, int fd, int events) |
942 | =item ev_io_init (ev_io *, callback, int fd, int events) |
895 | |
943 | |
896 | =item ev_io_set (ev_io *, int fd, int events) |
944 | =item ev_io_set (ev_io *, int fd, int events) |
… | |
… | |
948 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
996 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
949 | |
997 | |
950 | The callback is guarenteed to be invoked only when its timeout has passed, |
998 | The callback is guarenteed to be invoked only when its timeout has passed, |
951 | but if multiple timers become ready during the same loop iteration then |
999 | but if multiple timers become ready during the same loop iteration then |
952 | order of execution is undefined. |
1000 | order of execution is undefined. |
|
|
1001 | |
|
|
1002 | =head3 Watcher-Specific Functions and Data Members |
953 | |
1003 | |
954 | =over 4 |
1004 | =over 4 |
955 | |
1005 | |
956 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
1006 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
957 | |
1007 | |
… | |
… | |
1053 | but on wallclock time (absolute time). You can tell a periodic watcher |
1103 | but on wallclock time (absolute time). You can tell a periodic watcher |
1054 | to trigger "at" some specific point in time. For example, if you tell a |
1104 | to trigger "at" some specific point in time. For example, if you tell a |
1055 | periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now () |
1105 | periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now () |
1056 | + 10.>) and then reset your system clock to the last year, then it will |
1106 | + 10.>) and then reset your system clock to the last year, then it will |
1057 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
1107 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
1058 | roughly 10 seconds later and of course not if you reset your system time |
1108 | roughly 10 seconds later). |
1059 | again). |
|
|
1060 | |
1109 | |
1061 | They can also be used to implement vastly more complex timers, such as |
1110 | They can also be used to implement vastly more complex timers, such as |
1062 | triggering an event on eahc midnight, local time. |
1111 | triggering an event on each midnight, local time or other, complicated, |
|
|
1112 | rules. |
1063 | |
1113 | |
1064 | As with timers, the callback is guarenteed to be invoked only when the |
1114 | As with timers, the callback is guarenteed to be invoked only when the |
1065 | time (C<at>) has been passed, but if multiple periodic timers become ready |
1115 | time (C<at>) has been passed, but if multiple periodic timers become ready |
1066 | during the same loop iteration then order of execution is undefined. |
1116 | during the same loop iteration then order of execution is undefined. |
1067 | |
1117 | |
|
|
1118 | =head3 Watcher-Specific Functions and Data Members |
|
|
1119 | |
1068 | =over 4 |
1120 | =over 4 |
1069 | |
1121 | |
1070 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
1122 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
1071 | |
1123 | |
1072 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
1124 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
… | |
… | |
1074 | Lots of arguments, lets sort it out... There are basically three modes of |
1126 | Lots of arguments, lets sort it out... There are basically three modes of |
1075 | operation, and we will explain them from simplest to complex: |
1127 | operation, and we will explain them from simplest to complex: |
1076 | |
1128 | |
1077 | =over 4 |
1129 | =over 4 |
1078 | |
1130 | |
1079 | =item * absolute timer (interval = reschedule_cb = 0) |
1131 | =item * absolute timer (at = time, interval = reschedule_cb = 0) |
1080 | |
1132 | |
1081 | In this configuration the watcher triggers an event at the wallclock time |
1133 | In this configuration the watcher triggers an event at the wallclock time |
1082 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
1134 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
1083 | that is, if it is to be run at January 1st 2011 then it will run when the |
1135 | that is, if it is to be run at January 1st 2011 then it will run when the |
1084 | system time reaches or surpasses this time. |
1136 | system time reaches or surpasses this time. |
1085 | |
1137 | |
1086 | =item * non-repeating interval timer (interval > 0, reschedule_cb = 0) |
1138 | =item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
1087 | |
1139 | |
1088 | In this mode the watcher will always be scheduled to time out at the next |
1140 | In this mode the watcher will always be scheduled to time out at the next |
1089 | C<at + N * interval> time (for some integer N) and then repeat, regardless |
1141 | C<at + N * interval> time (for some integer N, which can also be negative) |
1090 | of any time jumps. |
1142 | and then repeat, regardless of any time jumps. |
1091 | |
1143 | |
1092 | This can be used to create timers that do not drift with respect to system |
1144 | This can be used to create timers that do not drift with respect to system |
1093 | time: |
1145 | time: |
1094 | |
1146 | |
1095 | ev_periodic_set (&periodic, 0., 3600., 0); |
1147 | ev_periodic_set (&periodic, 0., 3600., 0); |
… | |
… | |
1101 | |
1153 | |
1102 | Another way to think about it (for the mathematically inclined) is that |
1154 | Another way to think about it (for the mathematically inclined) is that |
1103 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1155 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1104 | time where C<time = at (mod interval)>, regardless of any time jumps. |
1156 | time where C<time = at (mod interval)>, regardless of any time jumps. |
1105 | |
1157 | |
|
|
1158 | For numerical stability it is preferable that the C<at> value is near |
|
|
1159 | C<ev_now ()> (the current time), but there is no range requirement for |
|
|
1160 | this value. |
|
|
1161 | |
1106 | =item * manual reschedule mode (reschedule_cb = callback) |
1162 | =item * manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
1107 | |
1163 | |
1108 | In this mode the values for C<interval> and C<at> are both being |
1164 | In this mode the values for C<interval> and C<at> are both being |
1109 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1165 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1110 | reschedule callback will be called with the watcher as first, and the |
1166 | reschedule callback will be called with the watcher as first, and the |
1111 | current time as second argument. |
1167 | current time as second argument. |
1112 | |
1168 | |
1113 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
1169 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
1114 | ever, or make any event loop modifications>. If you need to stop it, |
1170 | ever, or make any event loop modifications>. If you need to stop it, |
1115 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
1171 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
1116 | starting a prepare watcher). |
1172 | starting an C<ev_prepare> watcher, which is legal). |
1117 | |
1173 | |
1118 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1174 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1119 | ev_tstamp now)>, e.g.: |
1175 | ev_tstamp now)>, e.g.: |
1120 | |
1176 | |
1121 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
1177 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
… | |
… | |
1143 | |
1199 | |
1144 | Simply stops and restarts the periodic watcher again. This is only useful |
1200 | Simply stops and restarts the periodic watcher again. This is only useful |
1145 | when you changed some parameters or the reschedule callback would return |
1201 | when you changed some parameters or the reschedule callback would return |
1146 | a different time than the last time it was called (e.g. in a crond like |
1202 | a different time than the last time it was called (e.g. in a crond like |
1147 | program when the crontabs have changed). |
1203 | program when the crontabs have changed). |
|
|
1204 | |
|
|
1205 | =item ev_tstamp offset [read-write] |
|
|
1206 | |
|
|
1207 | When repeating, this contains the offset value, otherwise this is the |
|
|
1208 | absolute point in time (the C<at> value passed to C<ev_periodic_set>). |
|
|
1209 | |
|
|
1210 | Can be modified any time, but changes only take effect when the periodic |
|
|
1211 | timer fires or C<ev_periodic_again> is being called. |
1148 | |
1212 | |
1149 | =item ev_tstamp interval [read-write] |
1213 | =item ev_tstamp interval [read-write] |
1150 | |
1214 | |
1151 | The current interval value. Can be modified any time, but changes only |
1215 | The current interval value. Can be modified any time, but changes only |
1152 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
1216 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
… | |
… | |
1206 | with the kernel (thus it coexists with your own signal handlers as long |
1270 | with the kernel (thus it coexists with your own signal handlers as long |
1207 | as you don't register any with libev). Similarly, when the last signal |
1271 | as you don't register any with libev). Similarly, when the last signal |
1208 | watcher for a signal is stopped libev will reset the signal handler to |
1272 | watcher for a signal is stopped libev will reset the signal handler to |
1209 | SIG_DFL (regardless of what it was set to before). |
1273 | SIG_DFL (regardless of what it was set to before). |
1210 | |
1274 | |
|
|
1275 | =head3 Watcher-Specific Functions and Data Members |
|
|
1276 | |
1211 | =over 4 |
1277 | =over 4 |
1212 | |
1278 | |
1213 | =item ev_signal_init (ev_signal *, callback, int signum) |
1279 | =item ev_signal_init (ev_signal *, callback, int signum) |
1214 | |
1280 | |
1215 | =item ev_signal_set (ev_signal *, int signum) |
1281 | =item ev_signal_set (ev_signal *, int signum) |
… | |
… | |
1226 | |
1292 | |
1227 | =head2 C<ev_child> - watch out for process status changes |
1293 | =head2 C<ev_child> - watch out for process status changes |
1228 | |
1294 | |
1229 | Child watchers trigger when your process receives a SIGCHLD in response to |
1295 | Child watchers trigger when your process receives a SIGCHLD in response to |
1230 | some child status changes (most typically when a child of yours dies). |
1296 | some child status changes (most typically when a child of yours dies). |
|
|
1297 | |
|
|
1298 | =head3 Watcher-Specific Functions and Data Members |
1231 | |
1299 | |
1232 | =over 4 |
1300 | =over 4 |
1233 | |
1301 | |
1234 | =item ev_child_init (ev_child *, callback, int pid) |
1302 | =item ev_child_init (ev_child *, callback, int pid) |
1235 | |
1303 | |
… | |
… | |
1303 | reader). Inotify will be used to give hints only and should not change the |
1371 | reader). Inotify will be used to give hints only and should not change the |
1304 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
1372 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
1305 | to fall back to regular polling again even with inotify, but changes are |
1373 | to fall back to regular polling again even with inotify, but changes are |
1306 | usually detected immediately, and if the file exists there will be no |
1374 | usually detected immediately, and if the file exists there will be no |
1307 | polling. |
1375 | polling. |
|
|
1376 | |
|
|
1377 | =head3 Watcher-Specific Functions and Data Members |
1308 | |
1378 | |
1309 | =over 4 |
1379 | =over 4 |
1310 | |
1380 | |
1311 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1381 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1312 | |
1382 | |
… | |
… | |
1395 | Apart from keeping your process non-blocking (which is a useful |
1465 | Apart from keeping your process non-blocking (which is a useful |
1396 | effect on its own sometimes), idle watchers are a good place to do |
1466 | effect on its own sometimes), idle watchers are a good place to do |
1397 | "pseudo-background processing", or delay processing stuff to after the |
1467 | "pseudo-background processing", or delay processing stuff to after the |
1398 | event loop has handled all outstanding events. |
1468 | event loop has handled all outstanding events. |
1399 | |
1469 | |
|
|
1470 | =head3 Watcher-Specific Functions and Data Members |
|
|
1471 | |
1400 | =over 4 |
1472 | =over 4 |
1401 | |
1473 | |
1402 | =item ev_idle_init (ev_signal *, callback) |
1474 | =item ev_idle_init (ev_signal *, callback) |
1403 | |
1475 | |
1404 | Initialises and configures the idle watcher - it has no parameters of any |
1476 | Initialises and configures the idle watcher - it has no parameters of any |
… | |
… | |
1461 | with priority higher than or equal to the event loop and one coroutine |
1533 | with priority higher than or equal to the event loop and one coroutine |
1462 | of lower priority, but only once, using idle watchers to keep the event |
1534 | of lower priority, but only once, using idle watchers to keep the event |
1463 | loop from blocking if lower-priority coroutines are active, thus mapping |
1535 | loop from blocking if lower-priority coroutines are active, thus mapping |
1464 | low-priority coroutines to idle/background tasks). |
1536 | low-priority coroutines to idle/background tasks). |
1465 | |
1537 | |
|
|
1538 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
|
|
1539 | priority, to ensure that they are being run before any other watchers |
|
|
1540 | after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers, |
|
|
1541 | too) should not activate ("feed") events into libev. While libev fully |
|
|
1542 | supports this, they will be called before other C<ev_check> watchers did |
|
|
1543 | their job. As C<ev_check> watchers are often used to embed other event |
|
|
1544 | loops those other event loops might be in an unusable state until their |
|
|
1545 | C<ev_check> watcher ran (always remind yourself to coexist peacefully with |
|
|
1546 | others). |
|
|
1547 | |
|
|
1548 | =head3 Watcher-Specific Functions and Data Members |
|
|
1549 | |
1466 | =over 4 |
1550 | =over 4 |
1467 | |
1551 | |
1468 | =item ev_prepare_init (ev_prepare *, callback) |
1552 | =item ev_prepare_init (ev_prepare *, callback) |
1469 | |
1553 | |
1470 | =item ev_check_init (ev_check *, callback) |
1554 | =item ev_check_init (ev_check *, callback) |
… | |
… | |
1473 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1557 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1474 | macros, but using them is utterly, utterly and completely pointless. |
1558 | macros, but using them is utterly, utterly and completely pointless. |
1475 | |
1559 | |
1476 | =back |
1560 | =back |
1477 | |
1561 | |
1478 | Example: To include a library such as adns, you would add IO watchers |
1562 | There are a number of principal ways to embed other event loops or modules |
1479 | and a timeout watcher in a prepare handler, as required by libadns, and |
1563 | into libev. Here are some ideas on how to include libadns into libev |
|
|
1564 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
|
|
1565 | use for an actually working example. Another Perl module named C<EV::Glib> |
|
|
1566 | embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV |
|
|
1567 | into the Glib event loop). |
|
|
1568 | |
|
|
1569 | Method 1: Add IO watchers and a timeout watcher in a prepare handler, |
1480 | in a check watcher, destroy them and call into libadns. What follows is |
1570 | and in a check watcher, destroy them and call into libadns. What follows |
1481 | pseudo-code only of course: |
1571 | is pseudo-code only of course. This requires you to either use a low |
|
|
1572 | priority for the check watcher or use C<ev_clear_pending> explicitly, as |
|
|
1573 | the callbacks for the IO/timeout watchers might not have been called yet. |
1482 | |
1574 | |
1483 | static ev_io iow [nfd]; |
1575 | static ev_io iow [nfd]; |
1484 | static ev_timer tw; |
1576 | static ev_timer tw; |
1485 | |
1577 | |
1486 | static void |
1578 | static void |
1487 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1579 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1488 | { |
1580 | { |
1489 | // set the relevant poll flags |
|
|
1490 | // could also call adns_processreadable etc. here |
|
|
1491 | struct pollfd *fd = (struct pollfd *)w->data; |
|
|
1492 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1493 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1494 | } |
1581 | } |
1495 | |
1582 | |
1496 | // create io watchers for each fd and a timer before blocking |
1583 | // create io watchers for each fd and a timer before blocking |
1497 | static void |
1584 | static void |
1498 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1585 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
… | |
… | |
1504 | |
1591 | |
1505 | /* the callback is illegal, but won't be called as we stop during check */ |
1592 | /* the callback is illegal, but won't be called as we stop during check */ |
1506 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1593 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1507 | ev_timer_start (loop, &tw); |
1594 | ev_timer_start (loop, &tw); |
1508 | |
1595 | |
1509 | // create on ev_io per pollfd |
1596 | // create one ev_io per pollfd |
1510 | for (int i = 0; i < nfd; ++i) |
1597 | for (int i = 0; i < nfd; ++i) |
1511 | { |
1598 | { |
1512 | ev_io_init (iow + i, io_cb, fds [i].fd, |
1599 | ev_io_init (iow + i, io_cb, fds [i].fd, |
1513 | ((fds [i].events & POLLIN ? EV_READ : 0) |
1600 | ((fds [i].events & POLLIN ? EV_READ : 0) |
1514 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1601 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1515 | |
1602 | |
1516 | fds [i].revents = 0; |
1603 | fds [i].revents = 0; |
1517 | iow [i].data = fds + i; |
|
|
1518 | ev_io_start (loop, iow + i); |
1604 | ev_io_start (loop, iow + i); |
1519 | } |
1605 | } |
1520 | } |
1606 | } |
1521 | |
1607 | |
1522 | // stop all watchers after blocking |
1608 | // stop all watchers after blocking |
… | |
… | |
1524 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1610 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1525 | { |
1611 | { |
1526 | ev_timer_stop (loop, &tw); |
1612 | ev_timer_stop (loop, &tw); |
1527 | |
1613 | |
1528 | for (int i = 0; i < nfd; ++i) |
1614 | for (int i = 0; i < nfd; ++i) |
|
|
1615 | { |
|
|
1616 | // set the relevant poll flags |
|
|
1617 | // could also call adns_processreadable etc. here |
|
|
1618 | struct pollfd *fd = fds + i; |
|
|
1619 | int revents = ev_clear_pending (iow + i); |
|
|
1620 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1621 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1622 | |
|
|
1623 | // now stop the watcher |
1529 | ev_io_stop (loop, iow + i); |
1624 | ev_io_stop (loop, iow + i); |
|
|
1625 | } |
1530 | |
1626 | |
1531 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
1627 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
1628 | } |
|
|
1629 | |
|
|
1630 | Method 2: This would be just like method 1, but you run C<adns_afterpoll> |
|
|
1631 | in the prepare watcher and would dispose of the check watcher. |
|
|
1632 | |
|
|
1633 | Method 3: If the module to be embedded supports explicit event |
|
|
1634 | notification (adns does), you can also make use of the actual watcher |
|
|
1635 | callbacks, and only destroy/create the watchers in the prepare watcher. |
|
|
1636 | |
|
|
1637 | static void |
|
|
1638 | timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1639 | { |
|
|
1640 | adns_state ads = (adns_state)w->data; |
|
|
1641 | update_now (EV_A); |
|
|
1642 | |
|
|
1643 | adns_processtimeouts (ads, &tv_now); |
|
|
1644 | } |
|
|
1645 | |
|
|
1646 | static void |
|
|
1647 | io_cb (EV_P_ ev_io *w, int revents) |
|
|
1648 | { |
|
|
1649 | adns_state ads = (adns_state)w->data; |
|
|
1650 | update_now (EV_A); |
|
|
1651 | |
|
|
1652 | if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now); |
|
|
1653 | if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now); |
|
|
1654 | } |
|
|
1655 | |
|
|
1656 | // do not ever call adns_afterpoll |
|
|
1657 | |
|
|
1658 | Method 4: Do not use a prepare or check watcher because the module you |
|
|
1659 | want to embed is too inflexible to support it. Instead, youc na override |
|
|
1660 | their poll function. The drawback with this solution is that the main |
|
|
1661 | loop is now no longer controllable by EV. The C<Glib::EV> module does |
|
|
1662 | this. |
|
|
1663 | |
|
|
1664 | static gint |
|
|
1665 | event_poll_func (GPollFD *fds, guint nfds, gint timeout) |
|
|
1666 | { |
|
|
1667 | int got_events = 0; |
|
|
1668 | |
|
|
1669 | for (n = 0; n < nfds; ++n) |
|
|
1670 | // create/start io watcher that sets the relevant bits in fds[n] and increment got_events |
|
|
1671 | |
|
|
1672 | if (timeout >= 0) |
|
|
1673 | // create/start timer |
|
|
1674 | |
|
|
1675 | // poll |
|
|
1676 | ev_loop (EV_A_ 0); |
|
|
1677 | |
|
|
1678 | // stop timer again |
|
|
1679 | if (timeout >= 0) |
|
|
1680 | ev_timer_stop (EV_A_ &to); |
|
|
1681 | |
|
|
1682 | // stop io watchers again - their callbacks should have set |
|
|
1683 | for (n = 0; n < nfds; ++n) |
|
|
1684 | ev_io_stop (EV_A_ iow [n]); |
|
|
1685 | |
|
|
1686 | return got_events; |
1532 | } |
1687 | } |
1533 | |
1688 | |
1534 | |
1689 | |
1535 | =head2 C<ev_embed> - when one backend isn't enough... |
1690 | =head2 C<ev_embed> - when one backend isn't enough... |
1536 | |
1691 | |
… | |
… | |
1600 | ev_embed_start (loop_hi, &embed); |
1755 | ev_embed_start (loop_hi, &embed); |
1601 | } |
1756 | } |
1602 | else |
1757 | else |
1603 | loop_lo = loop_hi; |
1758 | loop_lo = loop_hi; |
1604 | |
1759 | |
|
|
1760 | =head3 Watcher-Specific Functions and Data Members |
|
|
1761 | |
1605 | =over 4 |
1762 | =over 4 |
1606 | |
1763 | |
1607 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
1764 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
1608 | |
1765 | |
1609 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
1766 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
… | |
… | |
1740 | |
1897 | |
1741 | To use it, |
1898 | To use it, |
1742 | |
1899 | |
1743 | #include <ev++.h> |
1900 | #include <ev++.h> |
1744 | |
1901 | |
1745 | (it is not installed by default). This automatically includes F<ev.h> |
1902 | This automatically includes F<ev.h> and puts all of its definitions (many |
1746 | and puts all of its definitions (many of them macros) into the global |
1903 | of them macros) into the global namespace. All C++ specific things are |
1747 | namespace. All C++ specific things are put into the C<ev> namespace. |
1904 | put into the C<ev> namespace. It should support all the same embedding |
|
|
1905 | options as F<ev.h>, most notably C<EV_MULTIPLICITY>. |
1748 | |
1906 | |
1749 | It should support all the same embedding options as F<ev.h>, most notably |
1907 | Care has been taken to keep the overhead low. The only data member the C++ |
1750 | C<EV_MULTIPLICITY>. |
1908 | classes add (compared to plain C-style watchers) is the event loop pointer |
|
|
1909 | that the watcher is associated with (or no additional members at all if |
|
|
1910 | you disable C<EV_MULTIPLICITY> when embedding libev). |
|
|
1911 | |
|
|
1912 | Currently, functions, and static and non-static member functions can be |
|
|
1913 | used as callbacks. Other types should be easy to add as long as they only |
|
|
1914 | need one additional pointer for context. If you need support for other |
|
|
1915 | types of functors please contact the author (preferably after implementing |
|
|
1916 | it). |
1751 | |
1917 | |
1752 | Here is a list of things available in the C<ev> namespace: |
1918 | Here is a list of things available in the C<ev> namespace: |
1753 | |
1919 | |
1754 | =over 4 |
1920 | =over 4 |
1755 | |
1921 | |
… | |
… | |
1771 | |
1937 | |
1772 | All of those classes have these methods: |
1938 | All of those classes have these methods: |
1773 | |
1939 | |
1774 | =over 4 |
1940 | =over 4 |
1775 | |
1941 | |
1776 | =item ev::TYPE::TYPE (object *, object::method *) |
1942 | =item ev::TYPE::TYPE () |
1777 | |
1943 | |
1778 | =item ev::TYPE::TYPE (object *, object::method *, struct ev_loop *) |
1944 | =item ev::TYPE::TYPE (struct ev_loop *) |
1779 | |
1945 | |
1780 | =item ev::TYPE::~TYPE |
1946 | =item ev::TYPE::~TYPE |
1781 | |
1947 | |
1782 | The constructor takes a pointer to an object and a method pointer to |
1948 | The constructor (optionally) takes an event loop to associate the watcher |
1783 | the event handler callback to call in this class. The constructor calls |
1949 | with. If it is omitted, it will use C<EV_DEFAULT>. |
1784 | C<ev_init> for you, which means you have to call the C<set> method |
1950 | |
1785 | before starting it. If you do not specify a loop then the constructor |
1951 | The constructor calls C<ev_init> for you, which means you have to call the |
1786 | automatically associates the default loop with this watcher. |
1952 | C<set> method before starting it. |
|
|
1953 | |
|
|
1954 | It will not set a callback, however: You have to call the templated C<set> |
|
|
1955 | method to set a callback before you can start the watcher. |
|
|
1956 | |
|
|
1957 | (The reason why you have to use a method is a limitation in C++ which does |
|
|
1958 | not allow explicit template arguments for constructors). |
1787 | |
1959 | |
1788 | The destructor automatically stops the watcher if it is active. |
1960 | The destructor automatically stops the watcher if it is active. |
|
|
1961 | |
|
|
1962 | =item w->set<class, &class::method> (object *) |
|
|
1963 | |
|
|
1964 | This method sets the callback method to call. The method has to have a |
|
|
1965 | signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as |
|
|
1966 | first argument and the C<revents> as second. The object must be given as |
|
|
1967 | parameter and is stored in the C<data> member of the watcher. |
|
|
1968 | |
|
|
1969 | This method synthesizes efficient thunking code to call your method from |
|
|
1970 | the C callback that libev requires. If your compiler can inline your |
|
|
1971 | callback (i.e. it is visible to it at the place of the C<set> call and |
|
|
1972 | your compiler is good :), then the method will be fully inlined into the |
|
|
1973 | thunking function, making it as fast as a direct C callback. |
|
|
1974 | |
|
|
1975 | Example: simple class declaration and watcher initialisation |
|
|
1976 | |
|
|
1977 | struct myclass |
|
|
1978 | { |
|
|
1979 | void io_cb (ev::io &w, int revents) { } |
|
|
1980 | } |
|
|
1981 | |
|
|
1982 | myclass obj; |
|
|
1983 | ev::io iow; |
|
|
1984 | iow.set <myclass, &myclass::io_cb> (&obj); |
|
|
1985 | |
|
|
1986 | =item w->set<function> (void *data = 0) |
|
|
1987 | |
|
|
1988 | Also sets a callback, but uses a static method or plain function as |
|
|
1989 | callback. The optional C<data> argument will be stored in the watcher's |
|
|
1990 | C<data> member and is free for you to use. |
|
|
1991 | |
|
|
1992 | The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>. |
|
|
1993 | |
|
|
1994 | See the method-C<set> above for more details. |
|
|
1995 | |
|
|
1996 | Example: |
|
|
1997 | |
|
|
1998 | static void io_cb (ev::io &w, int revents) { } |
|
|
1999 | iow.set <io_cb> (); |
1789 | |
2000 | |
1790 | =item w->set (struct ev_loop *) |
2001 | =item w->set (struct ev_loop *) |
1791 | |
2002 | |
1792 | Associates a different C<struct ev_loop> with this watcher. You can only |
2003 | Associates a different C<struct ev_loop> with this watcher. You can only |
1793 | do this when the watcher is inactive (and not pending either). |
2004 | do this when the watcher is inactive (and not pending either). |
1794 | |
2005 | |
1795 | =item w->set ([args]) |
2006 | =item w->set ([args]) |
1796 | |
2007 | |
1797 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
2008 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
1798 | called at least once. Unlike the C counterpart, an active watcher gets |
2009 | called at least once. Unlike the C counterpart, an active watcher gets |
1799 | automatically stopped and restarted. |
2010 | automatically stopped and restarted when reconfiguring it with this |
|
|
2011 | method. |
1800 | |
2012 | |
1801 | =item w->start () |
2013 | =item w->start () |
1802 | |
2014 | |
1803 | Starts the watcher. Note that there is no C<loop> argument as the |
2015 | Starts the watcher. Note that there is no C<loop> argument, as the |
1804 | constructor already takes the loop. |
2016 | constructor already stores the event loop. |
1805 | |
2017 | |
1806 | =item w->stop () |
2018 | =item w->stop () |
1807 | |
2019 | |
1808 | Stops the watcher if it is active. Again, no C<loop> argument. |
2020 | Stops the watcher if it is active. Again, no C<loop> argument. |
1809 | |
2021 | |
… | |
… | |
1834 | |
2046 | |
1835 | myclass (); |
2047 | myclass (); |
1836 | } |
2048 | } |
1837 | |
2049 | |
1838 | myclass::myclass (int fd) |
2050 | myclass::myclass (int fd) |
1839 | : io (this, &myclass::io_cb), |
|
|
1840 | idle (this, &myclass::idle_cb) |
|
|
1841 | { |
2051 | { |
|
|
2052 | io .set <myclass, &myclass::io_cb > (this); |
|
|
2053 | idle.set <myclass, &myclass::idle_cb> (this); |
|
|
2054 | |
1842 | io.start (fd, ev::READ); |
2055 | io.start (fd, ev::READ); |
1843 | } |
2056 | } |
1844 | |
2057 | |
1845 | |
2058 | |
1846 | =head1 MACRO MAGIC |
2059 | =head1 MACRO MAGIC |
… | |
… | |
2123 | will have the C<struct ev_loop *> as first argument, and you can create |
2336 | will have the C<struct ev_loop *> as first argument, and you can create |
2124 | additional independent event loops. Otherwise there will be no support |
2337 | additional independent event loops. Otherwise there will be no support |
2125 | for multiple event loops and there is no first event loop pointer |
2338 | for multiple event loops and there is no first event loop pointer |
2126 | argument. Instead, all functions act on the single default loop. |
2339 | argument. Instead, all functions act on the single default loop. |
2127 | |
2340 | |
|
|
2341 | =item EV_MINPRI |
|
|
2342 | |
|
|
2343 | =item EV_MAXPRI |
|
|
2344 | |
|
|
2345 | The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to |
|
|
2346 | C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can |
|
|
2347 | provide for more priorities by overriding those symbols (usually defined |
|
|
2348 | to be C<-2> and C<2>, respectively). |
|
|
2349 | |
|
|
2350 | When doing priority-based operations, libev usually has to linearly search |
|
|
2351 | all the priorities, so having many of them (hundreds) uses a lot of space |
|
|
2352 | and time, so using the defaults of five priorities (-2 .. +2) is usually |
|
|
2353 | fine. |
|
|
2354 | |
|
|
2355 | If your embedding app does not need any priorities, defining these both to |
|
|
2356 | C<0> will save some memory and cpu. |
|
|
2357 | |
2128 | =item EV_PERIODIC_ENABLE |
2358 | =item EV_PERIODIC_ENABLE |
2129 | |
2359 | |
2130 | If undefined or defined to be C<1>, then periodic timers are supported. If |
2360 | If undefined or defined to be C<1>, then periodic timers are supported. If |
2131 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
2361 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
2132 | code. |
2362 | code. |
… | |
… | |
2234 | |
2464 | |
2235 | In this section the complexities of (many of) the algorithms used inside |
2465 | In this section the complexities of (many of) the algorithms used inside |
2236 | libev will be explained. For complexity discussions about backends see the |
2466 | libev will be explained. For complexity discussions about backends see the |
2237 | documentation for C<ev_default_init>. |
2467 | documentation for C<ev_default_init>. |
2238 | |
2468 | |
|
|
2469 | All of the following are about amortised time: If an array needs to be |
|
|
2470 | extended, libev needs to realloc and move the whole array, but this |
|
|
2471 | happens asymptotically never with higher number of elements, so O(1) might |
|
|
2472 | mean it might do a lengthy realloc operation in rare cases, but on average |
|
|
2473 | it is much faster and asymptotically approaches constant time. |
|
|
2474 | |
2239 | =over 4 |
2475 | =over 4 |
2240 | |
2476 | |
2241 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2477 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2242 | |
2478 | |
|
|
2479 | This means that, when you have a watcher that triggers in one hour and |
|
|
2480 | there are 100 watchers that would trigger before that then inserting will |
|
|
2481 | have to skip those 100 watchers. |
|
|
2482 | |
2243 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
2483 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
2244 | |
2484 | |
|
|
2485 | That means that for changing a timer costs less than removing/adding them |
|
|
2486 | as only the relative motion in the event queue has to be paid for. |
|
|
2487 | |
2245 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2488 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2246 | |
2489 | |
|
|
2490 | These just add the watcher into an array or at the head of a list. |
2247 | =item Stopping check/prepare/idle watchers: O(1) |
2491 | =item Stopping check/prepare/idle watchers: O(1) |
2248 | |
2492 | |
2249 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2493 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2250 | |
2494 | |
|
|
2495 | These watchers are stored in lists then need to be walked to find the |
|
|
2496 | correct watcher to remove. The lists are usually short (you don't usually |
|
|
2497 | have many watchers waiting for the same fd or signal). |
|
|
2498 | |
2251 | =item Finding the next timer per loop iteration: O(1) |
2499 | =item Finding the next timer per loop iteration: O(1) |
2252 | |
2500 | |
2253 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2501 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2254 | |
2502 | |
|
|
2503 | A change means an I/O watcher gets started or stopped, which requires |
|
|
2504 | libev to recalculate its status (and possibly tell the kernel). |
|
|
2505 | |
2255 | =item Activating one watcher: O(1) |
2506 | =item Activating one watcher: O(1) |
2256 | |
2507 | |
|
|
2508 | =item Priority handling: O(number_of_priorities) |
|
|
2509 | |
|
|
2510 | Priorities are implemented by allocating some space for each |
|
|
2511 | priority. When doing priority-based operations, libev usually has to |
|
|
2512 | linearly search all the priorities. |
|
|
2513 | |
2257 | =back |
2514 | =back |
2258 | |
2515 | |
2259 | |
2516 | |
2260 | =head1 AUTHOR |
2517 | =head1 AUTHOR |
2261 | |
2518 | |