ViewVC Help
View File | Revision Log | Show Annotations | Download File
/cvs/libev/ev.3
(Generate patch)

Comparing libev/ev.3 (file contents):
Revision 1.51 by root, Wed Dec 12 17:55:30 2007 UTC vs.
Revision 1.57 by root, Sat Dec 22 11:49:17 2007 UTC

126. ds Ae AE 126. ds Ae AE
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 "EV 1"
132.TH "<STANDARD INPUT>" 1 "2007-12-12" "perl v5.8.8" "User Contributed Perl Documentation" 132.TH EV 1 "2007-12-22" "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
201The newest version of this document is also available as a html-formatted 201The newest version of this document is also available as a html-formatted
202web page you might find easier to navigate when reading it for the first 202web page you might find easier to navigate when reading it for the first
203time: <http://cvs.schmorp.de/libev/ev.html>. 203time: <http://cvs.schmorp.de/libev/ev.html>.
204.PP 204.PP
205Libev is an event loop: you register interest in certain events (such as a 205Libev is an event loop: you register interest in certain events (such as a
206file descriptor being readable or a timeout occuring), and it will manage 206file descriptor being readable or a timeout occurring), and it will manage
207these event sources and provide your program with events. 207these event sources and provide your program with events.
208.PP 208.PP
209To do this, it must take more or less complete control over your process 209To do this, it must take more or less complete control over your process
210(or thread) by executing the \fIevent loop\fR handler, and will then 210(or thread) by executing the \fIevent loop\fR handler, and will then
211communicate events via a callback mechanism. 211communicate events via a callback mechanism.
243Libev represents time as a single floating point number, representing the 243Libev represents time as a single floating point number, representing the
244(fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere near 244(fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere near
245the beginning of 1970, details are complicated, don't ask). This type is 245the beginning of 1970, details are complicated, don't ask). This type is
246called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually aliases 246called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually aliases
247to the \f(CW\*(C`double\*(C'\fR type in C, and when you need to do any calculations on 247to the \f(CW\*(C`double\*(C'\fR type in C, and when you need to do any calculations on
248it, you should treat it as such. 248it, you should treat it as some floatingpoint value. Unlike the name
249component \f(CW\*(C`stamp\*(C'\fR might indicate, it is also used for time differences
250throughout libev.
249.SH "GLOBAL FUNCTIONS" 251.SH "GLOBAL FUNCTIONS"
250.IX Header "GLOBAL FUNCTIONS" 252.IX Header "GLOBAL FUNCTIONS"
251These functions can be called anytime, even before initialising the 253These functions can be called anytime, even before initialising the
252library in any way. 254library in any way.
253.IP "ev_tstamp ev_time ()" 4 255.IP "ev_tstamp ev_time ()" 4
254.IX Item "ev_tstamp ev_time ()" 256.IX Item "ev_tstamp ev_time ()"
255Returns the current time as libev would use it. Please note that the 257Returns the current time as libev would use it. Please note that the
256\&\f(CW\*(C`ev_now\*(C'\fR function is usually faster and also often returns the timestamp 258\&\f(CW\*(C`ev_now\*(C'\fR function is usually faster and also often returns the timestamp
257you actually want to know. 259you actually want to know.
260.IP "ev_sleep (ev_tstamp interval)" 4
261.IX Item "ev_sleep (ev_tstamp interval)"
262Sleep for the given interval: The current thread will be blocked until
263either it is interrupted or the given time interval has passed. Basically
264this is a subsecond-resolution \f(CW\*(C`sleep ()\*(C'\fR.
258.IP "int ev_version_major ()" 4 265.IP "int ev_version_major ()" 4
259.IX Item "int ev_version_major ()" 266.IX Item "int ev_version_major ()"
260.PD 0 267.PD 0
261.IP "int ev_version_minor ()" 4 268.IP "int ev_version_minor ()" 4
262.IX Item "int ev_version_minor ()" 269.IX Item "int ev_version_minor ()"
457lot of inactive fds). It scales similarly to select, i.e. O(total_fds). 464lot of inactive fds). It scales similarly to select, i.e. O(total_fds).
458.ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 465.ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4
459.el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 466.el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4
460.IX Item "EVBACKEND_EPOLL (value 4, Linux)" 467.IX Item "EVBACKEND_EPOLL (value 4, Linux)"
461For few fds, this backend is a bit little slower than poll and select, 468For few fds, this backend is a bit little slower than poll and select,
462but it scales phenomenally better. While poll and select usually scale like 469but it scales phenomenally better. While poll and select usually scale
463O(total_fds) where n is the total number of fds (or the highest fd), epoll scales 470like O(total_fds) where n is the total number of fds (or the highest fd),
464either O(1) or O(active_fds). 471epoll scales either O(1) or O(active_fds). The epoll design has a number
472of shortcomings, such as silently dropping events in some hard-to-detect
473cases and rewiring a syscall per fd change, no fork support and bad
474support for dup:
465.Sp 475.Sp
466While stopping and starting an I/O watcher in the same iteration will 476While stopping, setting and starting an I/O watcher in the same iteration
467result in some caching, there is still a syscall per such incident 477will result in some caching, there is still a syscall per such incident
468(because the fd could point to a different file description now), so its 478(because the fd could point to a different file description now), so its
469best to avoid that. Also, \fIdup()\fRed file descriptors might not work very 479best to avoid that. Also, \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors might not work
470well if you register events for both fds. 480very well if you register events for both fds.
471.Sp 481.Sp
472Please note that epoll sometimes generates spurious notifications, so you 482Please note that epoll sometimes generates spurious notifications, so you
473need to use non-blocking I/O or other means to avoid blocking when no data 483need to use non-blocking I/O or other means to avoid blocking when no data
474(or space) is available. 484(or space) is available.
475.ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 485.ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4
476.el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 486.el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4
477.IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" 487.IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)"
478Kqueue deserves special mention, as at the time of this writing, it 488Kqueue deserves special mention, as at the time of this writing, it
479was broken on all BSDs except NetBSD (usually it doesn't work with 489was broken on all BSDs except NetBSD (usually it doesn't work reliably
480anything but sockets and pipes, except on Darwin, where of course its 490with anything but sockets and pipes, except on Darwin, where of course
481completely useless). For this reason its not being \*(L"autodetected\*(R" 491it's completely useless). For this reason it's not being \*(L"autodetected\*(R"
482unless you explicitly specify it explicitly in the flags (i.e. using 492unless you explicitly specify it explicitly in the flags (i.e. using
483\&\f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR). 493\&\f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR) or libev was compiled on a known-to-be-good (\-enough)
494system like NetBSD.
495.Sp
496You still can embed kqueue into a normal poll or select backend and use it
497only for sockets (after having made sure that sockets work with kqueue on
498the target platform). See \f(CW\*(C`ev_embed\*(C'\fR watchers for more info.
484.Sp 499.Sp
485It scales in the same way as the epoll backend, but the interface to the 500It scales in the same way as the epoll backend, but the interface to the
486kernel is more efficient (which says nothing about its actual speed, of 501kernel is more efficient (which says nothing about its actual speed, of
487course). While starting and stopping an I/O watcher does not cause an 502course). While stopping, setting and starting an I/O watcher does never
488extra syscall as with epoll, it still adds up to four event changes per 503cause an extra syscall as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to
489incident, so its best to avoid that. 504two event changes per incident, support for \f(CW\*(C`fork ()\*(C'\fR is very bad and it
505drops fds silently in similarly hard-to-detect cases.
490.ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 506.ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4
491.el .IP "\f(CWEVBACKEND_DEVPOLL\fR (value 16, Solaris 8)" 4 507.el .IP "\f(CWEVBACKEND_DEVPOLL\fR (value 16, Solaris 8)" 4
492.IX Item "EVBACKEND_DEVPOLL (value 16, Solaris 8)" 508.IX Item "EVBACKEND_DEVPOLL (value 16, Solaris 8)"
493This is not implemented yet (and might never be). 509This is not implemented yet (and might never be).
494.ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 510.ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4
495.el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 511.el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4
496.IX Item "EVBACKEND_PORT (value 32, Solaris 10)" 512.IX Item "EVBACKEND_PORT (value 32, Solaris 10)"
497This uses the Solaris 10 port mechanism. As with everything on Solaris, 513This uses the Solaris 10 event port mechanism. As with everything on Solaris,
498it's really slow, but it still scales very well (O(active_fds)). 514it's really slow, but it still scales very well (O(active_fds)).
499.Sp 515.Sp
500Please note that solaris ports can result in a lot of spurious 516Please note that solaris event ports can deliver a lot of spurious
501notifications, so you need to use non-blocking I/O or other means to avoid 517notifications, so you need to use non-blocking I/O or other means to avoid
502blocking when no data (or space) is available. 518blocking when no data (or space) is available.
503.ie n .IP """EVBACKEND_ALL""" 4 519.ie n .IP """EVBACKEND_ALL""" 4
504.el .IP "\f(CWEVBACKEND_ALL\fR" 4 520.el .IP "\f(CWEVBACKEND_ALL\fR" 4
505.IX Item "EVBACKEND_ALL" 521.IX Item "EVBACKEND_ALL"
555Destroys the default loop again (frees all memory and kernel state 571Destroys the default loop again (frees all memory and kernel state
556etc.). None of the active event watchers will be stopped in the normal 572etc.). None of the active event watchers will be stopped in the normal
557sense, so e.g. \f(CW\*(C`ev_is_active\*(C'\fR might still return true. It is your 573sense, so e.g. \f(CW\*(C`ev_is_active\*(C'\fR might still return true. It is your
558responsibility to either stop all watchers cleanly yoursef \fIbefore\fR 574responsibility to either stop all watchers cleanly yoursef \fIbefore\fR
559calling this function, or cope with the fact afterwards (which is usually 575calling this function, or cope with the fact afterwards (which is usually
560the easiest thing, youc na just ignore the watchers and/or \f(CW\*(C`free ()\*(C'\fR them 576the easiest thing, you can just ignore the watchers and/or \f(CW\*(C`free ()\*(C'\fR them
561for example). 577for example).
578.Sp
579Note that certain global state, such as signal state, will not be freed by
580this function, and related watchers (such as signal and child watchers)
581would need to be stopped manually.
582.Sp
583In general it is not advisable to call this function except in the
584rare occasion where you really need to free e.g. the signal handling
585pipe fds. If you need dynamically allocated loops it is better to use
586\&\f(CW\*(C`ev_loop_new\*(C'\fR and \f(CW\*(C`ev_loop_destroy\*(C'\fR).
562.IP "ev_loop_destroy (loop)" 4 587.IP "ev_loop_destroy (loop)" 4
563.IX Item "ev_loop_destroy (loop)" 588.IX Item "ev_loop_destroy (loop)"
564Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an 589Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an
565earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR. 590earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR.
566.IP "ev_default_fork ()" 4 591.IP "ev_default_fork ()" 4
607.IX Item "ev_tstamp ev_now (loop)" 632.IX Item "ev_tstamp ev_now (loop)"
608Returns the current \*(L"event loop time\*(R", which is the time the event loop 633Returns the current \*(L"event loop time\*(R", which is the time the event loop
609received events and started processing them. This timestamp does not 634received events and started processing them. This timestamp does not
610change as long as callbacks are being processed, and this is also the base 635change as long as callbacks are being processed, and this is also the base
611time used for relative timers. You can treat it as the timestamp of the 636time used for relative timers. You can treat it as the timestamp of the
612event occuring (or more correctly, libev finding out about it). 637event occurring (or more correctly, libev finding out about it).
613.IP "ev_loop (loop, int flags)" 4 638.IP "ev_loop (loop, int flags)" 4
614.IX Item "ev_loop (loop, int flags)" 639.IX Item "ev_loop (loop, int flags)"
615Finally, this is it, the event handler. This function usually is called 640Finally, this is it, the event handler. This function usually is called
616after you initialised all your watchers and you want to start handling 641after you initialised all your watchers and you want to start handling
617events. 642events.
707.Sp 732.Sp
708.Vb 2 733.Vb 2
709\& ev_ref (loop); 734\& ev_ref (loop);
710\& ev_signal_stop (loop, &exitsig); 735\& ev_signal_stop (loop, &exitsig);
711.Ve 736.Ve
737.IP "ev_set_io_collect_interval (loop, ev_tstamp interval)" 4
738.IX Item "ev_set_io_collect_interval (loop, ev_tstamp interval)"
739.PD 0
740.IP "ev_set_timeout_collect_interval (loop, ev_tstamp interval)" 4
741.IX Item "ev_set_timeout_collect_interval (loop, ev_tstamp interval)"
742.PD
743These advanced functions influence the time that libev will spend waiting
744for events. Both are by default \f(CW0\fR, meaning that libev will try to
745invoke timer/periodic callbacks and I/O callbacks with minimum latency.
746.Sp
747Setting these to a higher value (the \f(CW\*(C`interval\*(C'\fR \fImust\fR be >= \f(CW0\fR)
748allows libev to delay invocation of I/O and timer/periodic callbacks to
749increase efficiency of loop iterations.
750.Sp
751The background is that sometimes your program runs just fast enough to
752handle one (or very few) event(s) per loop iteration. While this makes
753the program responsive, it also wastes a lot of \s-1CPU\s0 time to poll for new
754events, especially with backends like \f(CW\*(C`select ()\*(C'\fR which have a high
755overhead for the actual polling but can deliver many events at once.
756.Sp
757By setting a higher \fIio collect interval\fR you allow libev to spend more
758time collecting I/O events, so you can handle more events per iteration,
759at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and
760\&\f(CW\*(C`ev_timer\*(C'\fR) will be not affected. Setting this to a non-null bvalue will
761introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations.
762.Sp
763Likewise, by setting a higher \fItimeout collect interval\fR you allow libev
764to spend more time collecting timeouts, at the expense of increased
765latency (the watcher callback will be called later). \f(CW\*(C`ev_io\*(C'\fR watchers
766will not be affected. Setting this to a non-null value will not introduce
767any overhead in libev.
768.Sp
769Many (busy) programs can usually benefit by setting the io collect
770interval to a value near \f(CW0.1\fR or so, which is often enough for
771interactive servers (of course not for games), likewise for timeouts. It
772usually doesn't make much sense to set it to a lower value than \f(CW0.01\fR,
773as this approsaches the timing granularity of most systems.
712.SH "ANATOMY OF A WATCHER" 774.SH "ANATOMY OF A WATCHER"
713.IX Header "ANATOMY OF A WATCHER" 775.IX Header "ANATOMY OF A WATCHER"
714A watcher is a structure that you create and register to record your 776A watcher is a structure that you create and register to record your
715interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to 777interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to
716become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher for that: 778become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher for that:
1069its own, so its quite safe to use). 1131its own, so its quite safe to use).
1070.PP 1132.PP
1071\fIThe special problem of disappearing file descriptors\fR 1133\fIThe special problem of disappearing file descriptors\fR
1072.IX Subsection "The special problem of disappearing file descriptors" 1134.IX Subsection "The special problem of disappearing file descriptors"
1073.PP 1135.PP
1074Some backends (e.g kqueue, epoll) need to be told about closing a file 1136Some 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, 1137descriptor (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 1138such 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 1139descriptor, but when it goes away, the operating system will silently drop
1078this interest. If another file descriptor with the same number then is 1140this 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 1141registered with libev, there is no efficient way to see that this is, in
1087descriptor even if the file descriptor number itself did not change. 1149descriptor even if the file descriptor number itself did not change.
1088.PP 1150.PP
1089This is how one would do it normally anyway, the important point is that 1151This is how one would do it normally anyway, the important point is that
1090the libev application should not optimise around libev but should leave 1152the libev application should not optimise around libev but should leave
1091optimisations to libev. 1153optimisations to libev.
1154.PP
1155\fIThe special problem of dup'ed file descriptors\fR
1156.IX Subsection "The special problem of dup'ed file descriptors"
1157.PP
1158Some backends (e.g. epoll), cannot register events for file descriptors,
1159but only events for the underlying file descriptions. That menas when you
1160have \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors and register events for them, only one
1161file descriptor might actually receive events.
1162.PP
1163There is no workaorund possible except not registering events
1164for potentially \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors or to resort to
1165\&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR.
1166.PP
1167\fIThe special problem of fork\fR
1168.IX Subsection "The special problem of fork"
1169.PP
1170Some backends (epoll, kqueue) do not support \f(CW\*(C`fork ()\*(C'\fR at all or exhibit
1171useless behaviour. Libev fully supports fork, but needs to be told about
1172it in the child.
1173.PP
1174To support fork in your programs, you either have to call
1175\&\f(CW\*(C`ev_default_fork ()\*(C'\fR or \f(CW\*(C`ev_loop_fork ()\*(C'\fR after a fork in the child,
1176enable \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR, or resort to \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or
1177\&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR.
1092.PP 1178.PP
1093\fIWatcher-Specific Functions\fR 1179\fIWatcher-Specific Functions\fR
1094.IX Subsection "Watcher-Specific Functions" 1180.IX Subsection "Watcher-Specific Functions"
1095.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 1181.IP "ev_io_init (ev_io *, callback, int fd, int events)" 4
1096.IX Item "ev_io_init (ev_io *, callback, int fd, int events)" 1182.IX Item "ev_io_init (ev_io *, callback, int fd, int events)"
1379.IP "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read\-write]" 4 1465.IP "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read\-write]" 4
1380.IX Item "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]" 1466.IX Item "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]"
1381The current reschedule callback, or \f(CW0\fR, if this functionality is 1467The current reschedule callback, or \f(CW0\fR, if this functionality is
1382switched off. Can be changed any time, but changes only take effect when 1468switched off. Can be changed any time, but changes only take effect when
1383the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. 1469the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called.
1470.IP "ev_tstamp at [read\-only]" 4
1471.IX Item "ev_tstamp at [read-only]"
1472When active, contains the absolute time that the watcher is supposed to
1473trigger next.
1384.PP 1474.PP
1385Example: Call a callback every hour, or, more precisely, whenever the 1475Example: Call a callback every hour, or, more precisely, whenever the
1386system clock is divisible by 3600. The callback invocation times have 1476system clock is divisible by 3600. The callback invocation times have
1387potentially a lot of jittering, but good long-term stability. 1477potentially a lot of jittering, but good long-term stability.
1388.PP 1478.PP
1697.PP 1787.PP
1698It is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR) 1788It is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR)
1699priority, to ensure that they are being run before any other watchers 1789priority, to ensure that they are being run before any other watchers
1700after the poll. Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers, 1790after the poll. Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers,
1701too) should not activate (\*(L"feed\*(R") events into libev. While libev fully 1791too) should not activate (\*(L"feed\*(R") events into libev. While libev fully
1702supports this, they will be called before other \f(CW\*(C`ev_check\*(C'\fR watchers did 1792supports this, they will be called before other \f(CW\*(C`ev_check\*(C'\fR watchers
1703their job. As \f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other event 1793did their job. As \f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other
1704loops those other event loops might be in an unusable state until their 1794(non\-libev) event loops those other event loops might be in an unusable
1705\&\f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to coexist peacefully with 1795state until their \f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to
1706others). 1796coexist peacefully with others).
1707.PP 1797.PP
1708\fIWatcher-Specific Functions and Data Members\fR 1798\fIWatcher-Specific Functions and Data Members\fR
1709.IX Subsection "Watcher-Specific Functions and Data Members" 1799.IX Subsection "Watcher-Specific Functions and Data Members"
1710.IP "ev_prepare_init (ev_prepare *, callback)" 4 1800.IP "ev_prepare_init (ev_prepare *, callback)" 4
1711.IX Item "ev_prepare_init (ev_prepare *, callback)" 1801.IX Item "ev_prepare_init (ev_prepare *, callback)"
1980.IP "ev_embed_sweep (loop, ev_embed *)" 4 2070.IP "ev_embed_sweep (loop, ev_embed *)" 4
1981.IX Item "ev_embed_sweep (loop, ev_embed *)" 2071.IX Item "ev_embed_sweep (loop, ev_embed *)"
1982Make a single, non-blocking sweep over the embedded loop. This works 2072Make a single, non-blocking sweep over the embedded loop. This works
1983similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most 2073similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most
1984apropriate way for embedded loops. 2074apropriate way for embedded loops.
1985.IP "struct ev_loop *loop [read\-only]" 4 2075.IP "struct ev_loop *other [read\-only]" 4
1986.IX Item "struct ev_loop *loop [read-only]" 2076.IX Item "struct ev_loop *other [read-only]"
1987The embedded event loop. 2077The embedded event loop.
1988.ie n .Sh """ev_fork"" \- the audacity to resume the event loop after a fork" 2078.ie n .Sh """ev_fork"" \- the audacity to resume the event loop after a fork"
1989.el .Sh "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" 2079.el .Sh "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork"
1990.IX Subsection "ev_fork - the audacity to resume the event loop after a fork" 2080.IX Subsection "ev_fork - the audacity to resume the event loop after a fork"
1991Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because 2081Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because
2199Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the 2289Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the
2200constructor already stores the event loop. 2290constructor already stores the event loop.
2201.IP "w\->stop ()" 4 2291.IP "w\->stop ()" 4
2202.IX Item "w->stop ()" 2292.IX Item "w->stop ()"
2203Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. 2293Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument.
2204.ie n .IP "w\->again () ""ev::timer""\fR, \f(CW""ev::periodic"" only" 4 2294.ie n .IP "w\->again () (""ev::timer""\fR, \f(CW""ev::periodic"" only)" 4
2205.el .IP "w\->again () \f(CWev::timer\fR, \f(CWev::periodic\fR only" 4 2295.el .IP "w\->again () (\f(CWev::timer\fR, \f(CWev::periodic\fR only)" 4
2206.IX Item "w->again () ev::timer, ev::periodic only" 2296.IX Item "w->again () (ev::timer, ev::periodic only)"
2207For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding 2297For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding
2208\&\f(CW\*(C`ev_TYPE_again\*(C'\fR function. 2298\&\f(CW\*(C`ev_TYPE_again\*(C'\fR function.
2209.ie n .IP "w\->sweep () ""ev::embed"" only" 4 2299.ie n .IP "w\->sweep () (""ev::embed"" only)" 4
2210.el .IP "w\->sweep () \f(CWev::embed\fR only" 4 2300.el .IP "w\->sweep () (\f(CWev::embed\fR only)" 4
2211.IX Item "w->sweep () ev::embed only" 2301.IX Item "w->sweep () (ev::embed only)"
2212Invokes \f(CW\*(C`ev_embed_sweep\*(C'\fR. 2302Invokes \f(CW\*(C`ev_embed_sweep\*(C'\fR.
2213.ie n .IP "w\->update () ""ev::stat"" only" 4 2303.ie n .IP "w\->update () (""ev::stat"" only)" 4
2214.el .IP "w\->update () \f(CWev::stat\fR only" 4 2304.el .IP "w\->update () (\f(CWev::stat\fR only)" 4
2215.IX Item "w->update () ev::stat only" 2305.IX Item "w->update () (ev::stat only)"
2216Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR. 2306Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR.
2217.RE 2307.RE
2218.RS 4 2308.RS 4
2219.RE 2309.RE
2220.PP 2310.PP
2244\& io.start (fd, ev::READ); 2334\& io.start (fd, ev::READ);
2245\& } 2335\& }
2246.Ve 2336.Ve
2247.SH "MACRO MAGIC" 2337.SH "MACRO MAGIC"
2248.IX Header "MACRO MAGIC" 2338.IX Header "MACRO MAGIC"
2249Libev can be compiled with a variety of options, the most fundemantal is 2339Libev can be compiled with a variety of options, the most fundamantal
2250\&\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) functions and 2340of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most)
2251callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. 2341functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument.
2252.PP 2342.PP
2253To make it easier to write programs that cope with either variant, the 2343To make it easier to write programs that cope with either variant, the
2254following macros are defined: 2344following macros are defined:
2255.ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4 2345.ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4
2256.el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4 2346.el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4
2315Libev can (and often is) directly embedded into host 2405Libev can (and often is) directly embedded into host
2316applications. Examples of applications that embed it include the Deliantra 2406applications. Examples of applications that embed it include the Deliantra
2317Game Server, the \s-1EV\s0 perl module, the \s-1GNU\s0 Virtual Private Ethernet (gvpe) 2407Game Server, the \s-1EV\s0 perl module, the \s-1GNU\s0 Virtual Private Ethernet (gvpe)
2318and rxvt\-unicode. 2408and rxvt\-unicode.
2319.PP 2409.PP
2320The goal is to enable you to just copy the neecssary files into your 2410The goal is to enable you to just copy the necessary files into your
2321source directory without having to change even a single line in them, so 2411source directory without having to change even a single line in them, so
2322you can easily upgrade by simply copying (or having a checked-out copy of 2412you can easily upgrade by simply copying (or having a checked-out copy of
2323libev somewhere in your source tree). 2413libev somewhere in your source tree).
2324.Sh "\s-1FILESETS\s0" 2414.Sh "\s-1FILESETS\s0"
2325.IX Subsection "FILESETS" 2415.IX Subsection "FILESETS"
2430.IX Item "EV_USE_MONOTONIC" 2520.IX Item "EV_USE_MONOTONIC"
2431If defined to be \f(CW1\fR, libev will try to detect the availability of the 2521If defined to be \f(CW1\fR, libev will try to detect the availability of the
2432monotonic clock option at both compiletime and runtime. Otherwise no use 2522monotonic clock option at both compiletime and runtime. Otherwise no use
2433of the monotonic clock option will be attempted. If you enable this, you 2523of the monotonic clock option will be attempted. If you enable this, you
2434usually have to link against librt or something similar. Enabling it when 2524usually have to link against librt or something similar. Enabling it when
2435the functionality isn't available is safe, though, althoguh you have 2525the functionality isn't available is safe, though, although you have
2436to make sure you link against any libraries where the \f(CW\*(C`clock_gettime\*(C'\fR 2526to make sure you link against any libraries where the \f(CW\*(C`clock_gettime\*(C'\fR
2437function is hiding in (often \fI\-lrt\fR). 2527function is hiding in (often \fI\-lrt\fR).
2438.IP "\s-1EV_USE_REALTIME\s0" 4 2528.IP "\s-1EV_USE_REALTIME\s0" 4
2439.IX Item "EV_USE_REALTIME" 2529.IX Item "EV_USE_REALTIME"
2440If defined to be \f(CW1\fR, libev will try to detect the availability of the 2530If defined to be \f(CW1\fR, libev will try to detect the availability of the
2441realtime clock option at compiletime (and assume its availability at 2531realtime clock option at compiletime (and assume its availability at
2442runtime if successful). Otherwise no use of the realtime clock option will 2532runtime if successful). Otherwise no use of the realtime clock option will
2443be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR by \f(CW\*(C`clock_get 2533be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR by \f(CW\*(C`clock_get
2444(CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect correctness. See tzhe note about libraries 2534(CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect correctness. See the
2445in the description of \f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though. 2535note about libraries in the description of \f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though.
2536.IP "\s-1EV_USE_NANOSLEEP\s0" 4
2537.IX Item "EV_USE_NANOSLEEP"
2538If defined to be \f(CW1\fR, libev will assume that \f(CW\*(C`nanosleep ()\*(C'\fR is available
2539and will use it for delays. Otherwise it will use \f(CW\*(C`select ()\*(C'\fR.
2446.IP "\s-1EV_USE_SELECT\s0" 4 2540.IP "\s-1EV_USE_SELECT\s0" 4
2447.IX Item "EV_USE_SELECT" 2541.IX Item "EV_USE_SELECT"
2448If undefined or defined to be \f(CW1\fR, libev will compile in support for the 2542If undefined or defined to be \f(CW1\fR, libev will compile in support for the
2449\&\f(CW\*(C`select\*(C'\fR(2) backend. No attempt at autodetection will be done: if no 2543\&\f(CW\*(C`select\*(C'\fR(2) backend. No attempt at autodetection will be done: if no
2450other method takes over, select will be it. Otherwise the select backend 2544other method takes over, select will be it. Otherwise the select backend
2610.IP "ev_set_cb (ev, cb)" 4 2704.IP "ev_set_cb (ev, cb)" 4
2611.IX Item "ev_set_cb (ev, cb)" 2705.IX Item "ev_set_cb (ev, cb)"
2612.PD 2706.PD
2613Can be used to change the callback member declaration in each watcher, 2707Can be used to change the callback member declaration in each watcher,
2614and the way callbacks are invoked and set. Must expand to a struct member 2708and the way callbacks are invoked and set. Must expand to a struct member
2615definition and a statement, respectively. See the \fIev.v\fR header file for 2709definition and a statement, respectively. See the \fIev.h\fR header file for
2616their default definitions. One possible use for overriding these is to 2710their default definitions. One possible use for overriding these is to
2617avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use 2711avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use
2618method calls instead of plain function calls in \*(C+. 2712method calls instead of plain function calls in \*(C+.
2713.Sh "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0"
2714.IX Subsection "EXPORTED API SYMBOLS"
2715If you need to re-export the \s-1API\s0 (e.g. via a dll) and you need a list of
2716exported symbols, you can use the provided \fISymbol.*\fR files which list
2717all public symbols, one per line:
2718.Sp
2719.Vb 2
2720\& Symbols.ev for libev proper
2721\& Symbols.event for the libevent emulation
2722.Ve
2723.Sp
2724This can also be used to rename all public symbols to avoid clashes with
2725multiple versions of libev linked together (which is obviously bad in
2726itself, but sometimes it is inconvinient to avoid this).
2727.Sp
2728A sed command like this will create wrapper \f(CW\*(C`#define\*(C'\fR's that you need to
2729include before including \fIev.h\fR:
2730.Sp
2731.Vb 1
2732\& <Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h
2733.Ve
2734.Sp
2735This would create a file \fIwrap.h\fR which essentially looks like this:
2736.Sp
2737.Vb 4
2738\& #define ev_backend myprefix_ev_backend
2739\& #define ev_check_start myprefix_ev_check_start
2740\& #define ev_check_stop myprefix_ev_check_stop
2741\& ...
2742.Ve
2619.Sh "\s-1EXAMPLES\s0" 2743.Sh "\s-1EXAMPLES\s0"
2620.IX Subsection "EXAMPLES" 2744.IX Subsection "EXAMPLES"
2621For a real-world example of a program the includes libev 2745For a real-world example of a program the includes libev
2622verbatim, you can have a look at the \s-1EV\s0 perl module 2746verbatim, you can have a look at the \s-1EV\s0 perl module
2623(<http://software.schmorp.de/pkg/EV.html>). It has the libev files in 2747(<http://software.schmorp.de/pkg/EV.html>). It has the libev files in

Diff Legend

Removed lines
+ Added lines
< Changed lines
> Changed lines