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Comparing libev/ev.3 (file contents):
Revision 1.48 by root, Sun Dec 9 19:47:29 2007 UTC vs.
Revision 1.51 by root, Wed Dec 12 17:55:30 2007 UTC

… …
127.\} 127.\}
128.rm #[ #] #H #V #F C 128.rm #[ #] #H #V #F C
129.\" ======================================================================== 129.\" ========================================================================
130.\" 130.\"
131.IX Title ""<STANDARD INPUT>" 1" 131.IX Title ""<STANDARD INPUT>" 1"
132.TH "<STANDARD INPUT>" 1 "2007-12-09" "perl v5.8.8" "User Contributed Perl Documentation" 132.TH "<STANDARD INPUT>" 1 "2007-12-12" "perl v5.8.8" "User Contributed Perl Documentation"
133.SH "NAME" 133.SH "NAME"
134libev \- a high performance full\-featured event loop written in C 134libev \- a high performance full\-featured event loop written in C
135.SH "SYNOPSIS" 135.SH "SYNOPSIS"
136.IX Header "SYNOPSIS" 136.IX Header "SYNOPSIS"
137.Vb 1 137.Vb 1
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1065If you cannot run the fd in non-blocking mode (for example you should not 1065If you cannot run the fd in non-blocking mode (for example you should not
1066play around with an Xlib connection), then you have to seperately re-test 1066play around with an Xlib connection), then you have to seperately re-test
1067whether a file descriptor is really ready with a known-to-be good interface 1067whether a file descriptor is really ready with a known-to-be good interface
1068such as poll (fortunately in our Xlib example, Xlib already does this on 1068such as poll (fortunately in our Xlib example, Xlib already does this on
1069its own, so its quite safe to use). 1069its own, so its quite safe to use).
1070.PP
1071\fIThe special problem of disappearing file descriptors\fR
1072.IX Subsection "The special problem of disappearing file descriptors"
1073.PP
1074Some backends (e.g kqueue, epoll) need to be told about closing a file
1075descriptor (either by calling \f(CW\*(C`close\*(C'\fR explicitly or by any other means,
1076such as \f(CW\*(C`dup\*(C'\fR). The reason is that you register interest in some file
1077descriptor, but when it goes away, the operating system will silently drop
1078this interest. If another file descriptor with the same number then is
1079registered with libev, there is no efficient way to see that this is, in
1080fact, a different file descriptor.
1081.PP
1082To avoid having to explicitly tell libev about such cases, libev follows
1083the following policy: Each time \f(CW\*(C`ev_io_set\*(C'\fR is being called, libev
1084will assume that this is potentially a new file descriptor, otherwise
1085it is assumed that the file descriptor stays the same. That means that
1086you \fIhave\fR to call \f(CW\*(C`ev_io_set\*(C'\fR (or \f(CW\*(C`ev_io_init\*(C'\fR) when you change the
1087descriptor even if the file descriptor number itself did not change.
1088.PP
1089This is how one would do it normally anyway, the important point is that
1090the libev application should not optimise around libev but should leave
1091optimisations to libev.
1092.PP
1093\fIWatcher-Specific Functions\fR
1094.IX Subsection "Watcher-Specific Functions"
1070.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 1095.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4
1071.IX Item "ev_io_init (ev_io *, callback, int fd, int events)" 1096.IX Item "ev_io_init (ev_io *, callback, int fd, int events)"
1072.PD 0 1097.PD 0
1073.IP "ev_io_set (ev_io *, int fd, int events)" 4 1098.IP "ev_io_set (ev_io *, int fd, int events)" 4
1074.IX Item "ev_io_set (ev_io *, int fd, int events)" 1099.IX Item "ev_io_set (ev_io *, int fd, int events)"
… …
1127.Ve 1152.Ve
1128.PP 1153.PP
1129The callback is guarenteed to be invoked only when its timeout has passed, 1154The callback is guarenteed to be invoked only when its timeout has passed,
1130but if multiple timers become ready during the same loop iteration then 1155but if multiple timers become ready during the same loop iteration then
1131order of execution is undefined. 1156order of execution is undefined.
1157.PP
1158\fIWatcher-Specific Functions and Data Members\fR
1159.IX Subsection "Watcher-Specific Functions and Data Members"
1132.IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4 1160.IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4
1133.IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 1161.IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)"
1134.PD 0 1162.PD 0
1135.IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4 1163.IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4
1136.IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 1164.IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)"
… …
1247rules. 1275rules.
1248.PP 1276.PP
1249As with timers, the callback is guarenteed to be invoked only when the 1277As with timers, the callback is guarenteed to be invoked only when the
1250time (\f(CW\*(C`at\*(C'\fR) has been passed, but if multiple periodic timers become ready 1278time (\f(CW\*(C`at\*(C'\fR) has been passed, but if multiple periodic timers become ready
1251during the same loop iteration then order of execution is undefined. 1279during the same loop iteration then order of execution is undefined.
1280.PP
1281\fIWatcher-Specific Functions and Data Members\fR
1282.IX Subsection "Watcher-Specific Functions and Data Members"
1252.IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4 1283.IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4
1253.IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 1284.IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)"
1254.PD 0 1285.PD 0
1255.IP "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 4 1286.IP "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 4
1256.IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 1287.IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)"
… …
1407first watcher gets started will libev actually register a signal watcher 1438first watcher gets started will libev actually register a signal watcher
1408with the kernel (thus it coexists with your own signal handlers as long 1439with the kernel (thus it coexists with your own signal handlers as long
1409as you don't register any with libev). Similarly, when the last signal 1440as you don't register any with libev). Similarly, when the last signal
1410watcher for a signal is stopped libev will reset the signal handler to 1441watcher for a signal is stopped libev will reset the signal handler to
1411\&\s-1SIG_DFL\s0 (regardless of what it was set to before). 1442\&\s-1SIG_DFL\s0 (regardless of what it was set to before).
1443.PP
1444\fIWatcher-Specific Functions and Data Members\fR
1445.IX Subsection "Watcher-Specific Functions and Data Members"
1412.IP "ev_signal_init (ev_signal *, callback, int signum)" 4 1446.IP "ev_signal_init (ev_signal *, callback, int signum)" 4
1413.IX Item "ev_signal_init (ev_signal *, callback, int signum)" 1447.IX Item "ev_signal_init (ev_signal *, callback, int signum)"
1414.PD 0 1448.PD 0
1415.IP "ev_signal_set (ev_signal *, int signum)" 4 1449.IP "ev_signal_set (ev_signal *, int signum)" 4
1416.IX Item "ev_signal_set (ev_signal *, int signum)" 1450.IX Item "ev_signal_set (ev_signal *, int signum)"
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1423.ie n .Sh """ev_child"" \- watch out for process status changes" 1457.ie n .Sh """ev_child"" \- watch out for process status changes"
1424.el .Sh "\f(CWev_child\fP \- watch out for process status changes" 1458.el .Sh "\f(CWev_child\fP \- watch out for process status changes"
1425.IX Subsection "ev_child - watch out for process status changes" 1459.IX Subsection "ev_child - watch out for process status changes"
1426Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to 1460Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to
1427some child status changes (most typically when a child of yours dies). 1461some child status changes (most typically when a child of yours dies).
1462.PP
1463\fIWatcher-Specific Functions and Data Members\fR
1464.IX Subsection "Watcher-Specific Functions and Data Members"
1428.IP "ev_child_init (ev_child *, callback, int pid)" 4 1465.IP "ev_child_init (ev_child *, callback, int pid)" 4
1429.IX Item "ev_child_init (ev_child *, callback, int pid)" 1466.IX Item "ev_child_init (ev_child *, callback, int pid)"
1430.PD 0 1467.PD 0
1431.IP "ev_child_set (ev_child *, int pid)" 4 1468.IP "ev_child_set (ev_child *, int pid)" 4
1432.IX Item "ev_child_set (ev_child *, int pid)" 1469.IX Item "ev_child_set (ev_child *, int pid)"
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1497reader). Inotify will be used to give hints only and should not change the 1534reader). Inotify will be used to give hints only and should not change the
1498semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers, which means that libev sometimes needs 1535semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers, which means that libev sometimes needs
1499to fall back to regular polling again even with inotify, but changes are 1536to fall back to regular polling again even with inotify, but changes are
1500usually detected immediately, and if the file exists there will be no 1537usually detected immediately, and if the file exists there will be no
1501polling. 1538polling.
1539.PP
1540\fIWatcher-Specific Functions and Data Members\fR
1541.IX Subsection "Watcher-Specific Functions and Data Members"
1502.IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4 1542.IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4
1503.IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 1543.IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)"
1504.PD 0 1544.PD 0
1505.IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4 1545.IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4
1506.IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 1546.IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)"
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1585.PP 1625.PP
1586Apart from keeping your process non-blocking (which is a useful 1626Apart from keeping your process non-blocking (which is a useful
1587effect on its own sometimes), idle watchers are a good place to do 1627effect on its own sometimes), idle watchers are a good place to do
1588\&\*(L"pseudo\-background processing\*(R", or delay processing stuff to after the 1628\&\*(L"pseudo\-background processing\*(R", or delay processing stuff to after the
1589event loop has handled all outstanding events. 1629event loop has handled all outstanding events.
1630.PP
1631\fIWatcher-Specific Functions and Data Members\fR
1632.IX Subsection "Watcher-Specific Functions and Data Members"
1590.IP "ev_idle_init (ev_signal *, callback)" 4 1633.IP "ev_idle_init (ev_signal *, callback)" 4
1591.IX Item "ev_idle_init (ev_signal *, callback)" 1634.IX Item "ev_idle_init (ev_signal *, callback)"
1592Initialises and configures the idle watcher \- it has no parameters of any 1635Initialises and configures the idle watcher \- it has no parameters of any
1593kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, 1636kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless,
1594believe me. 1637believe me.
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1659supports this, they will be called before other \f(CW\*(C`ev_check\*(C'\fR watchers did 1702supports this, they will be called before other \f(CW\*(C`ev_check\*(C'\fR watchers did
1660their job. As \f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other event 1703their job. As \f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other event
1661loops those other event loops might be in an unusable state until their 1704loops those other event loops might be in an unusable state until their
1662\&\f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to coexist peacefully with 1705\&\f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to coexist peacefully with
1663others). 1706others).
1707.PP
1708\fIWatcher-Specific Functions and Data Members\fR
1709.IX Subsection "Watcher-Specific Functions and Data Members"
1664.IP "ev_prepare_init (ev_prepare *, callback)" 4 1710.IP "ev_prepare_init (ev_prepare *, callback)" 4
1665.IX Item "ev_prepare_init (ev_prepare *, callback)" 1711.IX Item "ev_prepare_init (ev_prepare *, callback)"
1666.PD 0 1712.PD 0
1667.IP "ev_check_init (ev_check *, callback)" 4 1713.IP "ev_check_init (ev_check *, callback)" 4
1668.IX Item "ev_check_init (ev_check *, callback)" 1714.IX Item "ev_check_init (ev_check *, callback)"
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1915\& ev_embed_start (loop_hi, &embed); 1961\& ev_embed_start (loop_hi, &embed);
1916\& } 1962\& }
1917\& else 1963\& else
1918\& loop_lo = loop_hi; 1964\& loop_lo = loop_hi;
1919.Ve 1965.Ve
1966.PP
1967\fIWatcher-Specific Functions and Data Members\fR
1968.IX Subsection "Watcher-Specific Functions and Data Members"
1920.IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 1969.IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4
1921.IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 1970.IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)"
1922.PD 0 1971.PD 0
1923.IP "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 1972.IP "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 4
1924.IX Item "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 1973.IX Item "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)"
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1944\&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the 1993\&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the
1945event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, 1994event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called,
1946and only in the child after the fork. If whoever good citizen calling 1995and only in the child after the fork. If whoever good citizen calling
1947\&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork 1996\&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork
1948handlers will be invoked, too, of course. 1997handlers will be invoked, too, of course.
1998.PP
1999\fIWatcher-Specific Functions and Data Members\fR
2000.IX Subsection "Watcher-Specific Functions and Data Members"
1949.IP "ev_fork_init (ev_signal *, callback)" 4 2001.IP "ev_fork_init (ev_signal *, callback)" 4
1950.IX Item "ev_fork_init (ev_signal *, callback)" 2002.IX Item "ev_fork_init (ev_signal *, callback)"
1951Initialises and configures the fork watcher \- it has no parameters of any 2003Initialises and configures the fork watcher \- it has no parameters of any
1952kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless, 2004kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless,
1953believe me. 2005believe me.

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