… | |
… | |
117 | |
117 | |
118 | =item int ev_version_major () |
118 | =item int ev_version_major () |
119 | |
119 | |
120 | =item int ev_version_minor () |
120 | =item int ev_version_minor () |
121 | |
121 | |
122 | 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 |
123 | 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 |
124 | 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 |
125 | 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 |
126 | version of the library your program was compiled against. |
126 | version of the library your program was compiled against. |
127 | |
127 | |
|
|
128 | These version numbers refer to the ABI version of the library, not the |
|
|
129 | release version. |
|
|
130 | |
128 | 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, |
129 | as this indicates an incompatible change. Minor versions are usually |
132 | as this indicates an incompatible change. Minor versions are usually |
130 | 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 |
131 | not a problem. |
134 | not a problem. |
132 | |
135 | |
133 | 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 |
134 | version. |
137 | version. |
… | |
… | |
486 | 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 |
487 | usually a better approach for this kind of thing. |
490 | usually a better approach for this kind of thing. |
488 | |
491 | |
489 | Here are the gory details of what C<ev_loop> does: |
492 | Here are the gory details of what C<ev_loop> does: |
490 | |
493 | |
|
|
494 | - Before the first iteration, call any pending watchers. |
491 | * If there are no active watchers (reference count is zero), return. |
495 | * If there are no active watchers (reference count is zero), return. |
492 | - Queue prepare watchers and then call all outstanding watchers. |
496 | - Queue all prepare watchers and then call all outstanding watchers. |
493 | - If we have been forked, recreate the kernel state. |
497 | - If we have been forked, recreate the kernel state. |
494 | - Update the kernel state with all outstanding changes. |
498 | - Update the kernel state with all outstanding changes. |
495 | - Update the "event loop time". |
499 | - Update the "event loop time". |
496 | - Calculate for how long to block. |
500 | - Calculate for how long to block. |
497 | - Block the process, waiting for any events. |
501 | - Block the process, waiting for any events. |
… | |
… | |
907 | 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 |
908 | 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 |
909 | 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 |
910 | its own, so its quite safe to use). |
914 | its own, so its quite safe to use). |
911 | |
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 | |
912 | =over 4 |
940 | =over 4 |
913 | |
941 | |
914 | =item ev_io_init (ev_io *, callback, int fd, int events) |
942 | =item ev_io_init (ev_io *, callback, int fd, int events) |
915 | |
943 | |
916 | =item ev_io_set (ev_io *, int fd, int events) |
944 | =item ev_io_set (ev_io *, int fd, int events) |
… | |
… | |
968 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
996 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
969 | |
997 | |
970 | 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, |
971 | 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 |
972 | order of execution is undefined. |
1000 | order of execution is undefined. |
|
|
1001 | |
|
|
1002 | =head3 Watcher-Specific Functions and Data Members |
973 | |
1003 | |
974 | =over 4 |
1004 | =over 4 |
975 | |
1005 | |
976 | =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) |
977 | |
1007 | |
… | |
… | |
1073 | 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 |
1074 | 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 |
1075 | 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 () |
1076 | + 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 |
1077 | 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 |
1078 | roughly 10 seconds later and of course not if you reset your system time |
1108 | roughly 10 seconds later). |
1079 | again). |
|
|
1080 | |
1109 | |
1081 | 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 |
1082 | triggering an event on eahc midnight, local time. |
1111 | triggering an event on each midnight, local time or other, complicated, |
|
|
1112 | rules. |
1083 | |
1113 | |
1084 | 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 |
1085 | 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 |
1086 | during the same loop iteration then order of execution is undefined. |
1116 | during the same loop iteration then order of execution is undefined. |
1087 | |
1117 | |
|
|
1118 | =head3 Watcher-Specific Functions and Data Members |
|
|
1119 | |
1088 | =over 4 |
1120 | =over 4 |
1089 | |
1121 | |
1090 | =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) |
1091 | |
1123 | |
1092 | =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) |
… | |
… | |
1094 | 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 |
1095 | operation, and we will explain them from simplest to complex: |
1127 | operation, and we will explain them from simplest to complex: |
1096 | |
1128 | |
1097 | =over 4 |
1129 | =over 4 |
1098 | |
1130 | |
1099 | =item * absolute timer (interval = reschedule_cb = 0) |
1131 | =item * absolute timer (at = time, interval = reschedule_cb = 0) |
1100 | |
1132 | |
1101 | 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 |
1102 | 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, |
1103 | 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 |
1104 | system time reaches or surpasses this time. |
1136 | system time reaches or surpasses this time. |
1105 | |
1137 | |
1106 | =item * non-repeating interval timer (interval > 0, reschedule_cb = 0) |
1138 | =item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
1107 | |
1139 | |
1108 | 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 |
1109 | 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) |
1110 | of any time jumps. |
1142 | and then repeat, regardless of any time jumps. |
1111 | |
1143 | |
1112 | 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 |
1113 | time: |
1145 | time: |
1114 | |
1146 | |
1115 | ev_periodic_set (&periodic, 0., 3600., 0); |
1147 | ev_periodic_set (&periodic, 0., 3600., 0); |
… | |
… | |
1121 | |
1153 | |
1122 | 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 |
1123 | 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 |
1124 | 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. |
1125 | |
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 | |
1126 | =item * manual reschedule mode (reschedule_cb = callback) |
1162 | =item * manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
1127 | |
1163 | |
1128 | 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 |
1129 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1165 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1130 | 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 |
1131 | current time as second argument. |
1167 | current time as second argument. |
1132 | |
1168 | |
1133 | 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, |
1134 | 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, |
1135 | 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 |
1136 | starting a prepare watcher). |
1172 | starting an C<ev_prepare> watcher, which is legal). |
1137 | |
1173 | |
1138 | 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, |
1139 | ev_tstamp now)>, e.g.: |
1175 | ev_tstamp now)>, e.g.: |
1140 | |
1176 | |
1141 | 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) |
… | |
… | |
1163 | |
1199 | |
1164 | 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 |
1165 | when you changed some parameters or the reschedule callback would return |
1201 | when you changed some parameters or the reschedule callback would return |
1166 | 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 |
1167 | 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. |
1168 | |
1212 | |
1169 | =item ev_tstamp interval [read-write] |
1213 | =item ev_tstamp interval [read-write] |
1170 | |
1214 | |
1171 | 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 |
1172 | 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 |
… | |
… | |
1226 | 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 |
1227 | 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 |
1228 | 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 |
1229 | SIG_DFL (regardless of what it was set to before). |
1273 | SIG_DFL (regardless of what it was set to before). |
1230 | |
1274 | |
|
|
1275 | =head3 Watcher-Specific Functions and Data Members |
|
|
1276 | |
1231 | =over 4 |
1277 | =over 4 |
1232 | |
1278 | |
1233 | =item ev_signal_init (ev_signal *, callback, int signum) |
1279 | =item ev_signal_init (ev_signal *, callback, int signum) |
1234 | |
1280 | |
1235 | =item ev_signal_set (ev_signal *, int signum) |
1281 | =item ev_signal_set (ev_signal *, int signum) |
… | |
… | |
1246 | |
1292 | |
1247 | =head2 C<ev_child> - watch out for process status changes |
1293 | =head2 C<ev_child> - watch out for process status changes |
1248 | |
1294 | |
1249 | 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 |
1250 | 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 |
1251 | |
1299 | |
1252 | =over 4 |
1300 | =over 4 |
1253 | |
1301 | |
1254 | =item ev_child_init (ev_child *, callback, int pid) |
1302 | =item ev_child_init (ev_child *, callback, int pid) |
1255 | |
1303 | |
… | |
… | |
1323 | 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 |
1324 | 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 |
1325 | 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 |
1326 | 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 |
1327 | polling. |
1375 | polling. |
|
|
1376 | |
|
|
1377 | =head3 Watcher-Specific Functions and Data Members |
1328 | |
1378 | |
1329 | =over 4 |
1379 | =over 4 |
1330 | |
1380 | |
1331 | =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) |
1332 | |
1382 | |
… | |
… | |
1415 | Apart from keeping your process non-blocking (which is a useful |
1465 | Apart from keeping your process non-blocking (which is a useful |
1416 | 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 |
1417 | "pseudo-background processing", or delay processing stuff to after the |
1467 | "pseudo-background processing", or delay processing stuff to after the |
1418 | event loop has handled all outstanding events. |
1468 | event loop has handled all outstanding events. |
1419 | |
1469 | |
|
|
1470 | =head3 Watcher-Specific Functions and Data Members |
|
|
1471 | |
1420 | =over 4 |
1472 | =over 4 |
1421 | |
1473 | |
1422 | =item ev_idle_init (ev_signal *, callback) |
1474 | =item ev_idle_init (ev_signal *, callback) |
1423 | |
1475 | |
1424 | 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 |
… | |
… | |
1480 | are ready to run (it's actually more complicated: it only runs coroutines |
1532 | are ready to run (it's actually more complicated: it only runs coroutines |
1481 | 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 |
1482 | 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 |
1483 | loop from blocking if lower-priority coroutines are active, thus mapping |
1535 | loop from blocking if lower-priority coroutines are active, thus mapping |
1484 | low-priority coroutines to idle/background tasks). |
1536 | low-priority coroutines to idle/background tasks). |
|
|
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 |
1485 | |
1549 | |
1486 | =over 4 |
1550 | =over 4 |
1487 | |
1551 | |
1488 | =item ev_prepare_init (ev_prepare *, callback) |
1552 | =item ev_prepare_init (ev_prepare *, callback) |
1489 | |
1553 | |
… | |
… | |
1691 | ev_embed_start (loop_hi, &embed); |
1755 | ev_embed_start (loop_hi, &embed); |
1692 | } |
1756 | } |
1693 | else |
1757 | else |
1694 | loop_lo = loop_hi; |
1758 | loop_lo = loop_hi; |
1695 | |
1759 | |
|
|
1760 | =head3 Watcher-Specific Functions and Data Members |
|
|
1761 | |
1696 | =over 4 |
1762 | =over 4 |
1697 | |
1763 | |
1698 | =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) |
1699 | |
1765 | |
1700 | =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) |
… | |
… | |
1726 | event loop blocks next and before C<ev_check> watchers are being called, |
1792 | event loop blocks next and before C<ev_check> watchers are being called, |
1727 | and only in the child after the fork. If whoever good citizen calling |
1793 | and only in the child after the fork. If whoever good citizen calling |
1728 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
1794 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
1729 | handlers will be invoked, too, of course. |
1795 | handlers will be invoked, too, of course. |
1730 | |
1796 | |
|
|
1797 | =head3 Watcher-Specific Functions and Data Members |
|
|
1798 | |
1731 | =over 4 |
1799 | =over 4 |
1732 | |
1800 | |
1733 | =item ev_fork_init (ev_signal *, callback) |
1801 | =item ev_fork_init (ev_signal *, callback) |
1734 | |
1802 | |
1735 | Initialises and configures the fork watcher - it has no parameters of any |
1803 | Initialises and configures the fork watcher - it has no parameters of any |
… | |
… | |
1951 | |
2019 | |
1952 | =item w->stop () |
2020 | =item w->stop () |
1953 | |
2021 | |
1954 | Stops the watcher if it is active. Again, no C<loop> argument. |
2022 | Stops the watcher if it is active. Again, no C<loop> argument. |
1955 | |
2023 | |
1956 | =item w->again () C<ev::timer>, C<ev::periodic> only |
2024 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
1957 | |
2025 | |
1958 | For C<ev::timer> and C<ev::periodic>, this invokes the corresponding |
2026 | For C<ev::timer> and C<ev::periodic>, this invokes the corresponding |
1959 | C<ev_TYPE_again> function. |
2027 | C<ev_TYPE_again> function. |
1960 | |
2028 | |
1961 | =item w->sweep () C<ev::embed> only |
2029 | =item w->sweep () (C<ev::embed> only) |
1962 | |
2030 | |
1963 | Invokes C<ev_embed_sweep>. |
2031 | Invokes C<ev_embed_sweep>. |
1964 | |
2032 | |
1965 | =item w->update () C<ev::stat> only |
2033 | =item w->update () (C<ev::stat> only) |
1966 | |
2034 | |
1967 | Invokes C<ev_stat_stat>. |
2035 | Invokes C<ev_stat_stat>. |
1968 | |
2036 | |
1969 | =back |
2037 | =back |
1970 | |
2038 | |
… | |
… | |
1990 | } |
2058 | } |
1991 | |
2059 | |
1992 | |
2060 | |
1993 | =head1 MACRO MAGIC |
2061 | =head1 MACRO MAGIC |
1994 | |
2062 | |
1995 | Libev can be compiled with a variety of options, the most fundemantal is |
2063 | Libev can be compiled with a variety of options, the most fundamantal |
1996 | C<EV_MULTIPLICITY>. This option determines whether (most) functions and |
2064 | of which is C<EV_MULTIPLICITY>. This option determines whether (most) |
1997 | callbacks have an initial C<struct ev_loop *> argument. |
2065 | functions and callbacks have an initial C<struct ev_loop *> argument. |
1998 | |
2066 | |
1999 | To make it easier to write programs that cope with either variant, the |
2067 | To make it easier to write programs that cope with either variant, the |
2000 | following macros are defined: |
2068 | following macros are defined: |
2001 | |
2069 | |
2002 | =over 4 |
2070 | =over 4 |