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Revision 1.79 by root, Sun Dec 9 19:46:56 2007 UTC vs.
Revision 1.85 by root, Mon Dec 17 07:24:12 2007 UTC

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
122You can find out the major and minor API/ABI version numbers of the library 122You can find out the major and minor ABI version numbers of the library
123you linked against by calling the functions C<ev_version_major> and 123you linked against by calling the functions C<ev_version_major> and
124C<ev_version_minor>. If you want, you can compare against the global 124C<ev_version_minor>. If you want, you can compare against the global
125symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the 125symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the
126version of the library your program was compiled against. 126version of the library your program was compiled against.
127 127
128These version numbers refer to the API and ABI version of the library, not 128These version numbers refer to the ABI version of the library, not the
129the release version. 129release version.
130 130
131Usually, it's a good idea to terminate if the major versions mismatch, 131Usually, it's a good idea to terminate if the major versions mismatch,
132as this indicates an incompatible change. Minor versions are usually 132as this indicates an incompatible change. Minor versions are usually
133compatible to older versions, so a larger minor version alone is usually 133compatible to older versions, so a larger minor version alone is usually
134not a problem. 134not a problem.
911play around with an Xlib connection), then you have to seperately re-test 911play around with an Xlib connection), then you have to seperately re-test
912whether a file descriptor is really ready with a known-to-be good interface 912whether a file descriptor is really ready with a known-to-be good interface
913such as poll (fortunately in our Xlib example, Xlib already does this on 913such as poll (fortunately in our Xlib example, Xlib already does this on
914its own, so its quite safe to use). 914its own, so its quite safe to use).
915 915
916=head3 The special problem of disappearing file descriptors
917
918Some backends (e.g kqueue, epoll) need to be told about closing a file
919descriptor (either by calling C<close> explicitly or by any other means,
920such as C<dup>). The reason is that you register interest in some file
921descriptor, but when it goes away, the operating system will silently drop
922this interest. If another file descriptor with the same number then is
923registered with libev, there is no efficient way to see that this is, in
924fact, a different file descriptor.
925
926To avoid having to explicitly tell libev about such cases, libev follows
927the following policy: Each time C<ev_io_set> is being called, libev
928will assume that this is potentially a new file descriptor, otherwise
929it is assumed that the file descriptor stays the same. That means that
930you I<have> to call C<ev_io_set> (or C<ev_io_init>) when you change the
931descriptor even if the file descriptor number itself did not change.
932
933This is how one would do it normally anyway, the important point is that
934the libev application should not optimise around libev but should leave
935optimisations to libev.
936
937
938=head3 Watcher-Specific Functions
939
916=over 4 940=over 4
917 941
918=item ev_io_init (ev_io *, callback, int fd, int events) 942=item ev_io_init (ev_io *, callback, int fd, int events)
919 943
920=item ev_io_set (ev_io *, int fd, int events) 944=item ev_io_set (ev_io *, int fd, int events)
972 ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); 996 ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);
973 997
974The callback is guarenteed to be invoked only when its timeout has passed, 998The callback is guarenteed to be invoked only when its timeout has passed,
975but if multiple timers become ready during the same loop iteration then 999but if multiple timers become ready during the same loop iteration then
976order of execution is undefined. 1000order of execution is undefined.
1001
1002=head3 Watcher-Specific Functions and Data Members
977 1003
978=over 4 1004=over 4
979 1005
980=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)
981 1007
1087 1113
1088As with timers, the callback is guarenteed to be invoked only when the 1114As with timers, the callback is guarenteed to be invoked only when the
1089time (C<at>) has been passed, but if multiple periodic timers become ready 1115time (C<at>) has been passed, but if multiple periodic timers become ready
1090during the same loop iteration then order of execution is undefined. 1116during the same loop iteration then order of execution is undefined.
1091 1117
1118=head3 Watcher-Specific Functions and Data Members
1119
1092=over 4 1120=over 4
1093 1121
1094=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)
1095 1123
1096=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)
1191=item ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write] 1219=item ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]
1192 1220
1193The current reschedule callback, or C<0>, if this functionality is 1221The current reschedule callback, or C<0>, if this functionality is
1194switched off. Can be changed any time, but changes only take effect when 1222switched off. Can be changed any time, but changes only take effect when
1195the periodic timer fires or C<ev_periodic_again> is being called. 1223the periodic timer fires or C<ev_periodic_again> is being called.
1224
1225=item ev_tstamp at [read-only]
1226
1227When active, contains the absolute time that the watcher is supposed to
1228trigger next.
1196 1229
1197=back 1230=back
1198 1231
1199Example: Call a callback every hour, or, more precisely, whenever the 1232Example: Call a callback every hour, or, more precisely, whenever the
1200system clock is divisible by 3600. The callback invocation times have 1233system clock is divisible by 3600. The callback invocation times have
1242with the kernel (thus it coexists with your own signal handlers as long 1275with the kernel (thus it coexists with your own signal handlers as long
1243as you don't register any with libev). Similarly, when the last signal 1276as you don't register any with libev). Similarly, when the last signal
1244watcher for a signal is stopped libev will reset the signal handler to 1277watcher for a signal is stopped libev will reset the signal handler to
1245SIG_DFL (regardless of what it was set to before). 1278SIG_DFL (regardless of what it was set to before).
1246 1279
1280=head3 Watcher-Specific Functions and Data Members
1281
1247=over 4 1282=over 4
1248 1283
1249=item ev_signal_init (ev_signal *, callback, int signum) 1284=item ev_signal_init (ev_signal *, callback, int signum)
1250 1285
1251=item ev_signal_set (ev_signal *, int signum) 1286=item ev_signal_set (ev_signal *, int signum)
1262 1297
1263=head2 C<ev_child> - watch out for process status changes 1298=head2 C<ev_child> - watch out for process status changes
1264 1299
1265Child watchers trigger when your process receives a SIGCHLD in response to 1300Child watchers trigger when your process receives a SIGCHLD in response to
1266some child status changes (most typically when a child of yours dies). 1301some child status changes (most typically when a child of yours dies).
1302
1303=head3 Watcher-Specific Functions and Data Members
1267 1304
1268=over 4 1305=over 4
1269 1306
1270=item ev_child_init (ev_child *, callback, int pid) 1307=item ev_child_init (ev_child *, callback, int pid)
1271 1308
1339reader). Inotify will be used to give hints only and should not change the 1376reader). Inotify will be used to give hints only and should not change the
1340semantics of C<ev_stat> watchers, which means that libev sometimes needs 1377semantics of C<ev_stat> watchers, which means that libev sometimes needs
1341to fall back to regular polling again even with inotify, but changes are 1378to fall back to regular polling again even with inotify, but changes are
1342usually detected immediately, and if the file exists there will be no 1379usually detected immediately, and if the file exists there will be no
1343polling. 1380polling.
1381
1382=head3 Watcher-Specific Functions and Data Members
1344 1383
1345=over 4 1384=over 4
1346 1385
1347=item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) 1386=item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)
1348 1387
1431Apart from keeping your process non-blocking (which is a useful 1470Apart from keeping your process non-blocking (which is a useful
1432effect on its own sometimes), idle watchers are a good place to do 1471effect on its own sometimes), idle watchers are a good place to do
1433"pseudo-background processing", or delay processing stuff to after the 1472"pseudo-background processing", or delay processing stuff to after the
1434event loop has handled all outstanding events. 1473event loop has handled all outstanding events.
1435 1474
1475=head3 Watcher-Specific Functions and Data Members
1476
1436=over 4 1477=over 4
1437 1478
1438=item ev_idle_init (ev_signal *, callback) 1479=item ev_idle_init (ev_signal *, callback)
1439 1480
1440Initialises and configures the idle watcher - it has no parameters of any 1481Initialises and configures the idle watcher - it has no parameters of any
1507their job. As C<ev_check> watchers are often used to embed other event 1548their job. As C<ev_check> watchers are often used to embed other event
1508loops those other event loops might be in an unusable state until their 1549loops those other event loops might be in an unusable state until their
1509C<ev_check> watcher ran (always remind yourself to coexist peacefully with 1550C<ev_check> watcher ran (always remind yourself to coexist peacefully with
1510others). 1551others).
1511 1552
1553=head3 Watcher-Specific Functions and Data Members
1554
1512=over 4 1555=over 4
1513 1556
1514=item ev_prepare_init (ev_prepare *, callback) 1557=item ev_prepare_init (ev_prepare *, callback)
1515 1558
1516=item ev_check_init (ev_check *, callback) 1559=item ev_check_init (ev_check *, callback)
1717 ev_embed_start (loop_hi, &embed); 1760 ev_embed_start (loop_hi, &embed);
1718 } 1761 }
1719 else 1762 else
1720 loop_lo = loop_hi; 1763 loop_lo = loop_hi;
1721 1764
1765=head3 Watcher-Specific Functions and Data Members
1766
1722=over 4 1767=over 4
1723 1768
1724=item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) 1769=item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)
1725 1770
1726=item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) 1771=item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)
1752event loop blocks next and before C<ev_check> watchers are being called, 1797event loop blocks next and before C<ev_check> watchers are being called,
1753and only in the child after the fork. If whoever good citizen calling 1798and only in the child after the fork. If whoever good citizen calling
1754C<ev_default_fork> cheats and calls it in the wrong process, the fork 1799C<ev_default_fork> cheats and calls it in the wrong process, the fork
1755handlers will be invoked, too, of course. 1800handlers will be invoked, too, of course.
1756 1801
1802=head3 Watcher-Specific Functions and Data Members
1803
1757=over 4 1804=over 4
1758 1805
1759=item ev_fork_init (ev_signal *, callback) 1806=item ev_fork_init (ev_signal *, callback)
1760 1807
1761Initialises and configures the fork watcher - it has no parameters of any 1808Initialises and configures the fork watcher - it has no parameters of any
1977 2024
1978=item w->stop () 2025=item w->stop ()
1979 2026
1980Stops the watcher if it is active. Again, no C<loop> argument. 2027Stops the watcher if it is active. Again, no C<loop> argument.
1981 2028
1982=item w->again () C<ev::timer>, C<ev::periodic> only 2029=item w->again () (C<ev::timer>, C<ev::periodic> only)
1983 2030
1984For C<ev::timer> and C<ev::periodic>, this invokes the corresponding 2031For C<ev::timer> and C<ev::periodic>, this invokes the corresponding
1985C<ev_TYPE_again> function. 2032C<ev_TYPE_again> function.
1986 2033
1987=item w->sweep () C<ev::embed> only 2034=item w->sweep () (C<ev::embed> only)
1988 2035
1989Invokes C<ev_embed_sweep>. 2036Invokes C<ev_embed_sweep>.
1990 2037
1991=item w->update () C<ev::stat> only 2038=item w->update () (C<ev::stat> only)
1992 2039
1993Invokes C<ev_stat_stat>. 2040Invokes C<ev_stat_stat>.
1994 2041
1995=back 2042=back
1996 2043
2016 } 2063 }
2017 2064
2018 2065
2019=head1 MACRO MAGIC 2066=head1 MACRO MAGIC
2020 2067
2021Libev can be compiled with a variety of options, the most fundemantal is 2068Libev can be compiled with a variety of options, the most fundamantal
2022C<EV_MULTIPLICITY>. This option determines whether (most) functions and 2069of which is C<EV_MULTIPLICITY>. This option determines whether (most)
2023callbacks have an initial C<struct ev_loop *> argument. 2070functions and callbacks have an initial C<struct ev_loop *> argument.
2024 2071
2025To make it easier to write programs that cope with either variant, the 2072To make it easier to write programs that cope with either variant, the
2026following macros are defined: 2073following macros are defined:
2027 2074
2028=over 4 2075=over 4

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