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Comparing libev/ev.pod (file contents):
Revision 1.78 by root, Sun Dec 9 19:42:57 2007 UTC vs.
Revision 1.84 by root, Wed Dec 12 22:26:37 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 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 ABI version of the library, not the
129release version.
130
128Usually, 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,
129as this indicates an incompatible change. Minor versions are usually 132as this indicates an incompatible change. Minor versions are usually
130compatible to older versions, so a larger minor version alone is usually 133compatible to older versions, so a larger minor version alone is usually
131not a problem. 134not a problem.
132 135
133Example: Make sure we haven't accidentally been linked against the wrong 136Example: Make sure we haven't accidentally been linked against the wrong
134version. 137version.
908play 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
909whether 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
910such 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
911its own, so its quite safe to use). 914its own, so its quite safe to use).
912 915
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
913=over 4 940=over 4
914 941
915=item ev_io_init (ev_io *, callback, int fd, int events) 942=item ev_io_init (ev_io *, callback, int fd, int events)
916 943
917=item ev_io_set (ev_io *, int fd, int events) 944=item ev_io_set (ev_io *, int fd, int events)
969 ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); 996 ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);
970 997
971The 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,
972but if multiple timers become ready during the same loop iteration then 999but if multiple timers become ready during the same loop iteration then
973order of execution is undefined. 1000order of execution is undefined.
1001
1002=head3 Watcher-Specific Functions and Data Members
974 1003
975=over 4 1004=over 4
976 1005
977=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)
978 1007
1084 1113
1085As 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
1086time (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
1087during the same loop iteration then order of execution is undefined. 1116during the same loop iteration then order of execution is undefined.
1088 1117
1118=head3 Watcher-Specific Functions and Data Members
1119
1089=over 4 1120=over 4
1090 1121
1091=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)
1092 1123
1093=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)
1239with the kernel (thus it coexists with your own signal handlers as long 1270with the kernel (thus it coexists with your own signal handlers as long
1240as you don't register any with libev). Similarly, when the last signal 1271as you don't register any with libev). Similarly, when the last signal
1241watcher for a signal is stopped libev will reset the signal handler to 1272watcher for a signal is stopped libev will reset the signal handler to
1242SIG_DFL (regardless of what it was set to before). 1273SIG_DFL (regardless of what it was set to before).
1243 1274
1275=head3 Watcher-Specific Functions and Data Members
1276
1244=over 4 1277=over 4
1245 1278
1246=item ev_signal_init (ev_signal *, callback, int signum) 1279=item ev_signal_init (ev_signal *, callback, int signum)
1247 1280
1248=item ev_signal_set (ev_signal *, int signum) 1281=item ev_signal_set (ev_signal *, int signum)
1259 1292
1260=head2 C<ev_child> - watch out for process status changes 1293=head2 C<ev_child> - watch out for process status changes
1261 1294
1262Child watchers trigger when your process receives a SIGCHLD in response to 1295Child watchers trigger when your process receives a SIGCHLD in response to
1263some child status changes (most typically when a child of yours dies). 1296some child status changes (most typically when a child of yours dies).
1297
1298=head3 Watcher-Specific Functions and Data Members
1264 1299
1265=over 4 1300=over 4
1266 1301
1267=item ev_child_init (ev_child *, callback, int pid) 1302=item ev_child_init (ev_child *, callback, int pid)
1268 1303
1336reader). Inotify will be used to give hints only and should not change the 1371reader). Inotify will be used to give hints only and should not change the
1337semantics of C<ev_stat> watchers, which means that libev sometimes needs 1372semantics of C<ev_stat> watchers, which means that libev sometimes needs
1338to fall back to regular polling again even with inotify, but changes are 1373to fall back to regular polling again even with inotify, but changes are
1339usually detected immediately, and if the file exists there will be no 1374usually detected immediately, and if the file exists there will be no
1340polling. 1375polling.
1376
1377=head3 Watcher-Specific Functions and Data Members
1341 1378
1342=over 4 1379=over 4
1343 1380
1344=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)
1345 1382
1428Apart from keeping your process non-blocking (which is a useful 1465Apart from keeping your process non-blocking (which is a useful
1429effect on its own sometimes), idle watchers are a good place to do 1466effect on its own sometimes), idle watchers are a good place to do
1430"pseudo-background processing", or delay processing stuff to after the 1467"pseudo-background processing", or delay processing stuff to after the
1431event loop has handled all outstanding events. 1468event loop has handled all outstanding events.
1432 1469
1470=head3 Watcher-Specific Functions and Data Members
1471
1433=over 4 1472=over 4
1434 1473
1435=item ev_idle_init (ev_signal *, callback) 1474=item ev_idle_init (ev_signal *, callback)
1436 1475
1437Initialises and configures the idle watcher - it has no parameters of any 1476Initialises and configures the idle watcher - it has no parameters of any
1504their job. As C<ev_check> watchers are often used to embed other event 1543their job. As C<ev_check> watchers are often used to embed other event
1505loops those other event loops might be in an unusable state until their 1544loops those other event loops might be in an unusable state until their
1506C<ev_check> watcher ran (always remind yourself to coexist peacefully with 1545C<ev_check> watcher ran (always remind yourself to coexist peacefully with
1507others). 1546others).
1508 1547
1548=head3 Watcher-Specific Functions and Data Members
1549
1509=over 4 1550=over 4
1510 1551
1511=item ev_prepare_init (ev_prepare *, callback) 1552=item ev_prepare_init (ev_prepare *, callback)
1512 1553
1513=item ev_check_init (ev_check *, callback) 1554=item ev_check_init (ev_check *, callback)
1714 ev_embed_start (loop_hi, &embed); 1755 ev_embed_start (loop_hi, &embed);
1715 } 1756 }
1716 else 1757 else
1717 loop_lo = loop_hi; 1758 loop_lo = loop_hi;
1718 1759
1760=head3 Watcher-Specific Functions and Data Members
1761
1719=over 4 1762=over 4
1720 1763
1721=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)
1722 1765
1723=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)
1749event loop blocks next and before C<ev_check> watchers are being called, 1792event loop blocks next and before C<ev_check> watchers are being called,
1750and only in the child after the fork. If whoever good citizen calling 1793and only in the child after the fork. If whoever good citizen calling
1751C<ev_default_fork> cheats and calls it in the wrong process, the fork 1794C<ev_default_fork> cheats and calls it in the wrong process, the fork
1752handlers will be invoked, too, of course. 1795handlers will be invoked, too, of course.
1753 1796
1797=head3 Watcher-Specific Functions and Data Members
1798
1754=over 4 1799=over 4
1755 1800
1756=item ev_fork_init (ev_signal *, callback) 1801=item ev_fork_init (ev_signal *, callback)
1757 1802
1758Initialises and configures the fork watcher - it has no parameters of any 1803Initialises and configures the fork watcher - it has no parameters of any
1974 2019
1975=item w->stop () 2020=item w->stop ()
1976 2021
1977Stops the watcher if it is active. Again, no C<loop> argument. 2022Stops the watcher if it is active. Again, no C<loop> argument.
1978 2023
1979=item w->again () C<ev::timer>, C<ev::periodic> only 2024=item w->again () (C<ev::timer>, C<ev::periodic> only)
1980 2025
1981For C<ev::timer> and C<ev::periodic>, this invokes the corresponding 2026For C<ev::timer> and C<ev::periodic>, this invokes the corresponding
1982C<ev_TYPE_again> function. 2027C<ev_TYPE_again> function.
1983 2028
1984=item w->sweep () C<ev::embed> only 2029=item w->sweep () (C<ev::embed> only)
1985 2030
1986Invokes C<ev_embed_sweep>. 2031Invokes C<ev_embed_sweep>.
1987 2032
1988=item w->update () C<ev::stat> only 2033=item w->update () (C<ev::stat> only)
1989 2034
1990Invokes C<ev_stat_stat>. 2035Invokes C<ev_stat_stat>.
1991 2036
1992=back 2037=back
1993 2038
2013 } 2058 }
2014 2059
2015 2060
2016=head1 MACRO MAGIC 2061=head1 MACRO MAGIC
2017 2062
2018Libev can be compiled with a variety of options, the most fundemantal is 2063Libev can be compiled with a variety of options, the most fundamantal
2019C<EV_MULTIPLICITY>. This option determines whether (most) functions and 2064of which is C<EV_MULTIPLICITY>. This option determines whether (most)
2020callbacks have an initial C<struct ev_loop *> argument. 2065functions and callbacks have an initial C<struct ev_loop *> argument.
2021 2066
2022To make it easier to write programs that cope with either variant, the 2067To make it easier to write programs that cope with either variant, the
2023following macros are defined: 2068following macros are defined:
2024 2069
2025=over 4 2070=over 4

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