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Revision 1.231 by root, Wed Apr 15 19:35:53 2009 UTC vs.
Revision 1.277 by root, Thu Dec 31 06:50:17 2009 UTC

…		…
62		62
63	// unloop was called, so exit	63	// unloop was called, so exit
64	return 0;	64	return 0;
65	}	65	}
66		66
67	=head1 DESCRIPTION	67	=head1 ABOUT THIS DOCUMENT
		68
		69	This document documents the libev software package.
68		70
69	The newest version of this document is also available as an html-formatted	71	The newest version of this document is also available as an html-formatted
70	web page you might find easier to navigate when reading it for the first	72	web page you might find easier to navigate when reading it for the first
71	time: L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>.	73	time: L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>.
		74
		75	While this document tries to be as complete as possible in documenting
		76	libev, its usage and the rationale behind its design, it is not a tutorial
		77	on event-based programming, nor will it introduce event-based programming
		78	with libev.
		79
		80	Familarity with event based programming techniques in general is assumed
		81	throughout this document.
		82
		83	=head1 ABOUT LIBEV
72		84
73	Libev is an event loop: you register interest in certain events (such as a	85	Libev is an event loop: you register interest in certain events (such as a
74	file descriptor being readable or a timeout occurring), and it will manage	86	file descriptor being readable or a timeout occurring), and it will manage
75	these event sources and provide your program with events.	87	these event sources and provide your program with events.
76		88
…		…
86	=head2 FEATURES	98	=head2 FEATURES
87		99
88	Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the	100	Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the
89	BSD-specific C<kqueue> and the Solaris-specific event port mechanisms	101	BSD-specific C<kqueue> and the Solaris-specific event port mechanisms
90	for file descriptor events (C<ev_io>), the Linux C<inotify> interface	102	for file descriptor events (C<ev_io>), the Linux C<inotify> interface
91	(for C<ev_stat>), relative timers (C<ev_timer>), absolute timers	103	(for C<ev_stat>), Linux eventfd/signalfd (for faster and cleaner
92	with customised rescheduling (C<ev_periodic>), synchronous signals	104	inter-thread wakeup (C<ev_async>)/signal handling (C<ev_signal>)) relative
93	(C<ev_signal>), process status change events (C<ev_child>), and event	105	timers (C<ev_timer>), absolute timers with customised rescheduling
94	watchers dealing with the event loop mechanism itself (C<ev_idle>,	106	(C<ev_periodic>), synchronous signals (C<ev_signal>), process status
95	C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as	107	change events (C<ev_child>), and event watchers dealing with the event
96	file watchers (C<ev_stat>) and even limited support for fork events	108	loop mechanism itself (C<ev_idle>, C<ev_embed>, C<ev_prepare> and
97	(C<ev_fork>).	109	C<ev_check> watchers) as well as file watchers (C<ev_stat>) and even
		110	limited support for fork events (C<ev_fork>).
98		111
99	It also is quite fast (see this	112	It also is quite fast (see this
100	L<benchmark\|http://libev.schmorp.de/bench.html> comparing it to libevent	113	L<benchmark\|http://libev.schmorp.de/bench.html> comparing it to libevent
101	for example).	114	for example).
102		115
…		…
105	Libev is very configurable. In this manual the default (and most common)	118	Libev is very configurable. In this manual the default (and most common)
106	configuration will be described, which supports multiple event loops. For	119	configuration will be described, which supports multiple event loops. For
107	more info about various configuration options please have a look at	120	more info about various configuration options please have a look at
108	B<EMBED> section in this manual. If libev was configured without support	121	B<EMBED> section in this manual. If libev was configured without support
109	for multiple event loops, then all functions taking an initial argument of	122	for multiple event loops, then all functions taking an initial argument of
110	name C<loop> (which is always of type C<ev_loop *>) will not have	123	name C<loop> (which is always of type C<struct ev_loop *>) will not have
111	this argument.	124	this argument.
112		125
113	=head2 TIME REPRESENTATION	126	=head2 TIME REPRESENTATION
114		127
115	Libev represents time as a single floating point number, representing the	128	Libev represents time as a single floating point number, representing
116	(fractional) number of seconds since the (POSIX) epoch (somewhere near	129	the (fractional) number of seconds since the (POSIX) epoch (somewhere
117	the beginning of 1970, details are complicated, don't ask). This type is	130	near the beginning of 1970, details are complicated, don't ask). This
118	called C<ev_tstamp>, which is what you should use too. It usually aliases	131	type is called C<ev_tstamp>, which is what you should use too. It usually
119	to the C<double> type in C, and when you need to do any calculations on	132	aliases to the C<double> type in C. When you need to do any calculations
120	it, you should treat it as some floating point value. Unlike the name	133	on it, you should treat it as some floating point value. Unlike the name
121	component C<stamp> might indicate, it is also used for time differences	134	component C<stamp> might indicate, it is also used for time differences
122	throughout libev.	135	throughout libev.
123		136
124	=head1 ERROR HANDLING	137	=head1 ERROR HANDLING
125		138
…		…
350	flag.	363	flag.
351		364
352	This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS>	365	This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS>
353	environment variable.	366	environment variable.
354		367
		368	=item C<EVFLAG_NOINOTIFY>
		369
		370	When this flag is specified, then libev will not attempt to use the
		371	I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and
		372	testing, this flag can be useful to conserve inotify file descriptors, as
		373	otherwise each loop using C<ev_stat> watchers consumes one inotify handle.
		374
		375	=item C<EVFLAG_SIGNALFD>
		376
		377	When this flag is specified, then libev will attempt to use the
		378	I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This API
		379	delivers signals synchronously, which makes is both faster and might make
		380	it possible to get the queued signal data.
		381
		382	Signalfd will not be used by default as this changes your signal mask, and
		383	there are a lot of shoddy libraries and programs (glib's threadpool for
		384	example) that can't properly initialise their signal masks.
		385
355	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	386	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
356		387
357	This is your standard select(2) backend. Not I<completely> standard, as	388	This is your standard select(2) backend. Not I<completely> standard, as
358	libev tries to roll its own fd_set with no limits on the number of fds,	389	libev tries to roll its own fd_set with no limits on the number of fds,
359	but if that fails, expect a fairly low limit on the number of fds when	390	but if that fails, expect a fairly low limit on the number of fds when
…		…
382		413
383	This backend maps C<EV_READ> to C<POLLIN \| POLLERR \| POLLHUP>, and	414	This backend maps C<EV_READ> to C<POLLIN \| POLLERR \| POLLHUP>, and
384	C<EV_WRITE> to C<POLLOUT \| POLLERR \| POLLHUP>.	415	C<EV_WRITE> to C<POLLOUT \| POLLERR \| POLLHUP>.
385		416
386	=item C<EVBACKEND_EPOLL> (value 4, Linux)	417	=item C<EVBACKEND_EPOLL> (value 4, Linux)
		418
		419	Use the linux-specific epoll(7) interface (for both pre- and post-2.6.9
		420	kernels).
387		421
388	For few fds, this backend is a bit little slower than poll and select,	422	For few fds, this backend is a bit little slower than poll and select,
389	but it scales phenomenally better. While poll and select usually scale	423	but it scales phenomenally better. While poll and select usually scale
390	like O(total_fds) where n is the total number of fds (or the highest fd),	424	like O(total_fds) where n is the total number of fds (or the highest fd),
391	epoll scales either O(1) or O(active_fds).	425	epoll scales either O(1) or O(active_fds).
…		…
506		540
507	It is definitely not recommended to use this flag.	541	It is definitely not recommended to use this flag.
508		542
509	=back	543	=back
510		544
511	If one or more of these are or'ed into the flags value, then only these	545	If one or more of the backend flags are or'ed into the flags value,
512	backends will be tried (in the reverse order as listed here). If none are	546	then only these backends will be tried (in the reverse order as listed
513	specified, all backends in C<ev_recommended_backends ()> will be tried.	547	here). If none are specified, all backends in C<ev_recommended_backends
		548	()> will be tried.
514		549
515	Example: This is the most typical usage.	550	Example: This is the most typical usage.
516		551
517	if (!ev_default_loop (0))	552	if (!ev_default_loop (0))
518	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");	553	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
…		…
561	as signal and child watchers) would need to be stopped manually.	596	as signal and child watchers) would need to be stopped manually.
562		597
563	In general it is not advisable to call this function except in the	598	In general it is not advisable to call this function except in the
564	rare occasion where you really need to free e.g. the signal handling	599	rare occasion where you really need to free e.g. the signal handling
565	pipe fds. If you need dynamically allocated loops it is better to use	600	pipe fds. If you need dynamically allocated loops it is better to use
566	C<ev_loop_new> and C<ev_loop_destroy>).	601	C<ev_loop_new> and C<ev_loop_destroy>.
567		602
568	=item ev_loop_destroy (loop)	603	=item ev_loop_destroy (loop)
569		604
570	Like C<ev_default_destroy>, but destroys an event loop created by an	605	Like C<ev_default_destroy>, but destroys an event loop created by an
571	earlier call to C<ev_loop_new>.	606	earlier call to C<ev_loop_new>.
…		…
609		644
610	This value can sometimes be useful as a generation counter of sorts (it	645	This value can sometimes be useful as a generation counter of sorts (it
611	"ticks" the number of loop iterations), as it roughly corresponds with	646	"ticks" the number of loop iterations), as it roughly corresponds with
612	C<ev_prepare> and C<ev_check> calls.	647	C<ev_prepare> and C<ev_check> calls.
613		648
		649	=item unsigned int ev_loop_depth (loop)
		650
		651	Returns the number of times C<ev_loop> was entered minus the number of
		652	times C<ev_loop> was exited, in other words, the recursion depth.
		653
		654	Outside C<ev_loop>, this number is zero. In a callback, this number is
		655	C<1>, unless C<ev_loop> was invoked recursively (or from another thread),
		656	in which case it is higher.
		657
		658	Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread
		659	etc.), doesn't count as exit.
		660
614	=item unsigned int ev_backend (loop)	661	=item unsigned int ev_backend (loop)
615		662
616	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	663	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
617	use.	664	use.
618		665
…		…
632		679
633	This function is rarely useful, but when some event callback runs for a	680	This function is rarely useful, but when some event callback runs for a
634	very long time without entering the event loop, updating libev's idea of	681	very long time without entering the event loop, updating libev's idea of
635	the current time is a good idea.	682	the current time is a good idea.
636		683
637	See also "The special problem of time updates" in the C<ev_timer> section.	684	See also L<The special problem of time updates> in the C<ev_timer> section.
638		685
639	=item ev_suspend (loop)	686	=item ev_suspend (loop)
640		687
641	=item ev_resume (loop)	688	=item ev_resume (loop)
642		689
…		…
663	event loop time (see C<ev_now_update>).	710	event loop time (see C<ev_now_update>).
664		711
665	=item ev_loop (loop, int flags)	712	=item ev_loop (loop, int flags)
666		713
667	Finally, this is it, the event handler. This function usually is called	714	Finally, this is it, the event handler. This function usually is called
668	after you initialised all your watchers and you want to start handling	715	after you have initialised all your watchers and you want to start
669	events.	716	handling events.
670		717
671	If the flags argument is specified as C<0>, it will not return until	718	If the flags argument is specified as C<0>, it will not return until
672	either no event watchers are active anymore or C<ev_unloop> was called.	719	either no event watchers are active anymore or C<ev_unloop> was called.
673		720
674	Please note that an explicit C<ev_unloop> is usually better than	721	Please note that an explicit C<ev_unloop> is usually better than
…		…
748		795
749	Ref/unref can be used to add or remove a reference count on the event	796	Ref/unref can be used to add or remove a reference count on the event
750	loop: Every watcher keeps one reference, and as long as the reference	797	loop: Every watcher keeps one reference, and as long as the reference
751	count is nonzero, C<ev_loop> will not return on its own.	798	count is nonzero, C<ev_loop> will not return on its own.
752		799
753	If you have a watcher you never unregister that should not keep C<ev_loop>	800	This is useful when you have a watcher that you never intend to
754	from returning, call ev_unref() after starting, and ev_ref() before	801	unregister, but that nevertheless should not keep C<ev_loop> from
		802	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>
755	stopping it.	803	before stopping it.
756		804
757	As an example, libev itself uses this for its internal signal pipe: It	805	As an example, libev itself uses this for its internal signal pipe: It
758	is not visible to the libev user and should not keep C<ev_loop> from	806	is not visible to the libev user and should not keep C<ev_loop> from
759	exiting if no event watchers registered by it are active. It is also an	807	exiting if no event watchers registered by it are active. It is also an
760	excellent way to do this for generic recurring timers or from within	808	excellent way to do this for generic recurring timers or from within
…		…
799		847
800	By setting a higher I<io collect interval> you allow libev to spend more	848	By setting a higher I<io collect interval> you allow libev to spend more
801	time collecting I/O events, so you can handle more events per iteration,	849	time collecting I/O events, so you can handle more events per iteration,
802	at the cost of increasing latency. Timeouts (both C<ev_periodic> and	850	at the cost of increasing latency. Timeouts (both C<ev_periodic> and
803	C<ev_timer>) will be not affected. Setting this to a non-null value will	851	C<ev_timer>) will be not affected. Setting this to a non-null value will
804	introduce an additional C<ev_sleep ()> call into most loop iterations.	852	introduce an additional C<ev_sleep ()> call into most loop iterations. The
		853	sleep time ensures that libev will not poll for I/O events more often then
		854	once per this interval, on average.
805		855
806	Likewise, by setting a higher I<timeout collect interval> you allow libev	856	Likewise, by setting a higher I<timeout collect interval> you allow libev
807	to spend more time collecting timeouts, at the expense of increased	857	to spend more time collecting timeouts, at the expense of increased
808	latency/jitter/inexactness (the watcher callback will be called	858	latency/jitter/inexactness (the watcher callback will be called
809	later). C<ev_io> watchers will not be affected. Setting this to a non-null	859	later). C<ev_io> watchers will not be affected. Setting this to a non-null
…		…
811		861
812	Many (busy) programs can usually benefit by setting the I/O collect	862	Many (busy) programs can usually benefit by setting the I/O collect
813	interval to a value near C<0.1> or so, which is often enough for	863	interval to a value near C<0.1> or so, which is often enough for
814	interactive servers (of course not for games), likewise for timeouts. It	864	interactive servers (of course not for games), likewise for timeouts. It
815	usually doesn't make much sense to set it to a lower value than C<0.01>,	865	usually doesn't make much sense to set it to a lower value than C<0.01>,
816	as this approaches the timing granularity of most systems.	866	as this approaches the timing granularity of most systems. Note that if
		867	you do transactions with the outside world and you can't increase the
		868	parallelity, then this setting will limit your transaction rate (if you
		869	need to poll once per transaction and the I/O collect interval is 0.01,
		870	then you can't do more than 100 transations per second).
817		871
818	Setting the I<timeout collect interval> can improve the opportunity for	872	Setting the I<timeout collect interval> can improve the opportunity for
819	saving power, as the program will "bundle" timer callback invocations that	873	saving power, as the program will "bundle" timer callback invocations that
820	are "near" in time together, by delaying some, thus reducing the number of	874	are "near" in time together, by delaying some, thus reducing the number of
821	times the process sleeps and wakes up again. Another useful technique to	875	times the process sleeps and wakes up again. Another useful technique to
822	reduce iterations/wake-ups is to use C<ev_periodic> watchers and make sure	876	reduce iterations/wake-ups is to use C<ev_periodic> watchers and make sure
823	they fire on, say, one-second boundaries only.	877	they fire on, say, one-second boundaries only.
		878
		879	Example: we only need 0.1s timeout granularity, and we wish not to poll
		880	more often than 100 times per second:
		881
		882	ev_set_timeout_collect_interval (EV_DEFAULT_UC_ 0.1);
		883	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);
		884
		885	=item ev_invoke_pending (loop)
		886
		887	This call will simply invoke all pending watchers while resetting their
		888	pending state. Normally, C<ev_loop> does this automatically when required,
		889	but when overriding the invoke callback this call comes handy.
		890
		891	=item int ev_pending_count (loop)
		892
		893	Returns the number of pending watchers - zero indicates that no watchers
		894	are pending.
		895
		896	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))
		897
		898	This overrides the invoke pending functionality of the loop: Instead of
		899	invoking all pending watchers when there are any, C<ev_loop> will call
		900	this callback instead. This is useful, for example, when you want to
		901	invoke the actual watchers inside another context (another thread etc.).
		902
		903	If you want to reset the callback, use C<ev_invoke_pending> as new
		904	callback.
		905
		906	=item ev_set_loop_release_cb (loop, void (release)(EV_P), void (acquire)(EV_P))
		907
		908	Sometimes you want to share the same loop between multiple threads. This
		909	can be done relatively simply by putting mutex_lock/unlock calls around
		910	each call to a libev function.
		911
		912	However, C<ev_loop> can run an indefinite time, so it is not feasible to
		913	wait for it to return. One way around this is to wake up the loop via
		914	C<ev_unloop> and C<av_async_send>, another way is to set these I<release>
		915	and I<acquire> callbacks on the loop.
		916
		917	When set, then C<release> will be called just before the thread is
		918	suspended waiting for new events, and C<acquire> is called just
		919	afterwards.
		920
		921	Ideally, C<release> will just call your mutex_unlock function, and
		922	C<acquire> will just call the mutex_lock function again.
		923
		924	While event loop modifications are allowed between invocations of
		925	C<release> and C<acquire> (that's their only purpose after all), no
		926	modifications done will affect the event loop, i.e. adding watchers will
		927	have no effect on the set of file descriptors being watched, or the time
		928	waited. Use an C<ev_async> watcher to wake up C<ev_loop> when you want it
		929	to take note of any changes you made.
		930
		931	In theory, threads executing C<ev_loop> will be async-cancel safe between
		932	invocations of C<release> and C<acquire>.
		933
		934	See also the locking example in the C<THREADS> section later in this
		935	document.
		936
		937	=item ev_set_userdata (loop, void *data)
		938
		939	=item ev_userdata (loop)
		940
		941	Set and retrieve a single C<void *> associated with a loop. When
		942	C<ev_set_userdata> has never been called, then C<ev_userdata> returns
		943	C<0.>
		944
		945	These two functions can be used to associate arbitrary data with a loop,
		946	and are intended solely for the C<invoke_pending_cb>, C<release> and
		947	C<acquire> callbacks described above, but of course can be (ab-)used for
		948	any other purpose as well.
824		949
825	=item ev_loop_verify (loop)	950	=item ev_loop_verify (loop)
826		951
827	This function only does something when C<EV_VERIFY> support has been	952	This function only does something when C<EV_VERIFY> support has been
828	compiled in, which is the default for non-minimal builds. It tries to go	953	compiled in, which is the default for non-minimal builds. It tries to go
…		…
1005		1130
1006	ev_io w;	1131	ev_io w;
1007	ev_init (&w, my_cb);	1132	ev_init (&w, my_cb);
1008	ev_io_set (&w, STDIN_FILENO, EV_READ);	1133	ev_io_set (&w, STDIN_FILENO, EV_READ);
1009		1134
1010	=item C<ev_TYPE_set> (ev_TYPE *, [args])	1135	=item C<ev_TYPE_set> (ev_TYPE *watcher, [args])
1011		1136
1012	This macro initialises the type-specific parts of a watcher. You need to	1137	This macro initialises the type-specific parts of a watcher. You need to
1013	call C<ev_init> at least once before you call this macro, but you can	1138	call C<ev_init> at least once before you call this macro, but you can
1014	call C<ev_TYPE_set> any number of times. You must not, however, call this	1139	call C<ev_TYPE_set> any number of times. You must not, however, call this
1015	macro on a watcher that is active (it can be pending, however, which is a	1140	macro on a watcher that is active (it can be pending, however, which is a
…		…
1028		1153
1029	Example: Initialise and set an C<ev_io> watcher in one step.	1154	Example: Initialise and set an C<ev_io> watcher in one step.
1030		1155
1031	ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ);	1156	ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ);
1032		1157
1033	=item C<ev_TYPE_start> (loop , ev_TYPE watcher)	1158	=item C<ev_TYPE_start> (loop, ev_TYPE *watcher)
1034		1159
1035	Starts (activates) the given watcher. Only active watchers will receive	1160	Starts (activates) the given watcher. Only active watchers will receive
1036	events. If the watcher is already active nothing will happen.	1161	events. If the watcher is already active nothing will happen.
1037		1162
1038	Example: Start the C<ev_io> watcher that is being abused as example in this	1163	Example: Start the C<ev_io> watcher that is being abused as example in this
1039	whole section.	1164	whole section.
1040		1165
1041	ev_io_start (EV_DEFAULT_UC, &w);	1166	ev_io_start (EV_DEFAULT_UC, &w);
1042		1167
1043	=item C<ev_TYPE_stop> (loop , ev_TYPE watcher)	1168	=item C<ev_TYPE_stop> (loop, ev_TYPE *watcher)
1044		1169
1045	Stops the given watcher if active, and clears the pending status (whether	1170	Stops the given watcher if active, and clears the pending status (whether
1046	the watcher was active or not).	1171	the watcher was active or not).
1047		1172
1048	It is possible that stopped watchers are pending - for example,	1173	It is possible that stopped watchers are pending - for example,
…		…
1073	=item ev_cb_set (ev_TYPE *watcher, callback)	1198	=item ev_cb_set (ev_TYPE *watcher, callback)
1074		1199
1075	Change the callback. You can change the callback at virtually any time	1200	Change the callback. You can change the callback at virtually any time
1076	(modulo threads).	1201	(modulo threads).
1077		1202
1078	=item ev_set_priority (ev_TYPE *watcher, priority)	1203	=item ev_set_priority (ev_TYPE *watcher, int priority)
1079		1204
1080	=item int ev_priority (ev_TYPE *watcher)	1205	=item int ev_priority (ev_TYPE *watcher)
1081		1206
1082	Set and query the priority of the watcher. The priority is a small	1207	Set and query the priority of the watcher. The priority is a small
1083	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>	1208	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>
1084	(default: C<-2>). Pending watchers with higher priority will be invoked	1209	(default: C<-2>). Pending watchers with higher priority will be invoked
1085	before watchers with lower priority, but priority will not keep watchers	1210	before watchers with lower priority, but priority will not keep watchers
1086	from being executed (except for C<ev_idle> watchers).	1211	from being executed (except for C<ev_idle> watchers).
1087		1212
1088	This means that priorities are I<only> used for ordering callback
1089	invocation after new events have been received. This is useful, for
1090	example, to reduce latency after idling, or more often, to bind two
1091	watchers on the same event and make sure one is called first.
1092
1093	If you need to suppress invocation when higher priority events are pending	1213	If you need to suppress invocation when higher priority events are pending
1094	you need to look at C<ev_idle> watchers, which provide this functionality.	1214	you need to look at C<ev_idle> watchers, which provide this functionality.
1095		1215
1096	You I<must not> change the priority of a watcher as long as it is active or	1216	You I<must not> change the priority of a watcher as long as it is active or
1097	pending.	1217	pending.
1098
1099	The default priority used by watchers when no priority has been set is
1100	always C<0>, which is supposed to not be too high and not be too low :).
1101		1218
1102	Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is	1219	Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is
1103	fine, as long as you do not mind that the priority value you query might	1220	fine, as long as you do not mind that the priority value you query might
1104	or might not have been clamped to the valid range.	1221	or might not have been clamped to the valid range.
		1222
		1223	The default priority used by watchers when no priority has been set is
		1224	always C<0>, which is supposed to not be too high and not be too low :).
		1225
		1226	See L<WATCHER PRIORITY MODELS>, below, for a more thorough treatment of
		1227	priorities.
1105		1228
1106	=item ev_invoke (loop, ev_TYPE *watcher, int revents)	1229	=item ev_invoke (loop, ev_TYPE *watcher, int revents)
1107		1230
1108	Invoke the C<watcher> with the given C<loop> and C<revents>. Neither	1231	Invoke the C<watcher> with the given C<loop> and C<revents>. Neither
1109	C<loop> nor C<revents> need to be valid as long as the watcher callback	1232	C<loop> nor C<revents> need to be valid as long as the watcher callback
…		…
1116	returns its C<revents> bitset (as if its callback was invoked). If the	1239	returns its C<revents> bitset (as if its callback was invoked). If the
1117	watcher isn't pending it does nothing and returns C<0>.	1240	watcher isn't pending it does nothing and returns C<0>.
1118		1241
1119	Sometimes it can be useful to "poll" a watcher instead of waiting for its	1242	Sometimes it can be useful to "poll" a watcher instead of waiting for its
1120	callback to be invoked, which can be accomplished with this function.	1243	callback to be invoked, which can be accomplished with this function.
		1244
		1245	=item ev_feed_event (loop, ev_TYPE *watcher, int revents)
		1246
		1247	Feeds the given event set into the event loop, as if the specified event
		1248	had happened for the specified watcher (which must be a pointer to an
		1249	initialised but not necessarily started event watcher). Obviously you must
		1250	not free the watcher as long as it has pending events.
		1251
		1252	Stopping the watcher, letting libev invoke it, or calling
		1253	C<ev_clear_pending> will clear the pending event, even if the watcher was
		1254	not started in the first place.
		1255
		1256	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related
		1257	functions that do not need a watcher.
1121		1258
1122	=back	1259	=back
1123		1260
1124		1261
1125	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	1262	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
1174	#include <stddef.h>	1311	#include <stddef.h>
1175		1312
1176	static void	1313	static void
1177	t1_cb (EV_P_ ev_timer *w, int revents)	1314	t1_cb (EV_P_ ev_timer *w, int revents)
1178	{	1315	{
1179	struct my_biggy big = (struct my_biggy *	1316	struct my_biggy big = (struct my_biggy *)
1180	(((char *)w) - offsetof (struct my_biggy, t1));	1317	(((char *)w) - offsetof (struct my_biggy, t1));
1181	}	1318	}
1182		1319
1183	static void	1320	static void
1184	t2_cb (EV_P_ ev_timer *w, int revents)	1321	t2_cb (EV_P_ ev_timer *w, int revents)
1185	{	1322	{
1186	struct my_biggy big = (struct my_biggy *	1323	struct my_biggy big = (struct my_biggy *)
1187	(((char *)w) - offsetof (struct my_biggy, t2));	1324	(((char *)w) - offsetof (struct my_biggy, t2));
1188	}	1325	}
		1326
		1327	=head2 WATCHER PRIORITY MODELS
		1328
		1329	Many event loops support I<watcher priorities>, which are usually small
		1330	integers that influence the ordering of event callback invocation
		1331	between watchers in some way, all else being equal.
		1332
		1333	In libev, Watcher priorities can be set using C<ev_set_priority>. See its
		1334	description for the more technical details such as the actual priority
		1335	range.
		1336
		1337	There are two common ways how these these priorities are being interpreted
		1338	by event loops:
		1339
		1340	In the more common lock-out model, higher priorities "lock out" invocation
		1341	of lower priority watchers, which means as long as higher priority
		1342	watchers receive events, lower priority watchers are not being invoked.
		1343
		1344	The less common only-for-ordering model uses priorities solely to order
		1345	callback invocation within a single event loop iteration: Higher priority
		1346	watchers are invoked before lower priority ones, but they all get invoked
		1347	before polling for new events.
		1348
		1349	Libev uses the second (only-for-ordering) model for all its watchers
		1350	except for idle watchers (which use the lock-out model).
		1351
		1352	The rationale behind this is that implementing the lock-out model for
		1353	watchers is not well supported by most kernel interfaces, and most event
		1354	libraries will just poll for the same events again and again as long as
		1355	their callbacks have not been executed, which is very inefficient in the
		1356	common case of one high-priority watcher locking out a mass of lower
		1357	priority ones.
		1358
		1359	Static (ordering) priorities are most useful when you have two or more
		1360	watchers handling the same resource: a typical usage example is having an
		1361	C<ev_io> watcher to receive data, and an associated C<ev_timer> to handle
		1362	timeouts. Under load, data might be received while the program handles
		1363	other jobs, but since timers normally get invoked first, the timeout
		1364	handler will be executed before checking for data. In that case, giving
		1365	the timer a lower priority than the I/O watcher ensures that I/O will be
		1366	handled first even under adverse conditions (which is usually, but not
		1367	always, what you want).
		1368
		1369	Since idle watchers use the "lock-out" model, meaning that idle watchers
		1370	will only be executed when no same or higher priority watchers have
		1371	received events, they can be used to implement the "lock-out" model when
		1372	required.
		1373
		1374	For example, to emulate how many other event libraries handle priorities,
		1375	you can associate an C<ev_idle> watcher to each such watcher, and in
		1376	the normal watcher callback, you just start the idle watcher. The real
		1377	processing is done in the idle watcher callback. This causes libev to
		1378	continously poll and process kernel event data for the watcher, but when
		1379	the lock-out case is known to be rare (which in turn is rare :), this is
		1380	workable.
		1381
		1382	Usually, however, the lock-out model implemented that way will perform
		1383	miserably under the type of load it was designed to handle. In that case,
		1384	it might be preferable to stop the real watcher before starting the
		1385	idle watcher, so the kernel will not have to process the event in case
		1386	the actual processing will be delayed for considerable time.
		1387
		1388	Here is an example of an I/O watcher that should run at a strictly lower
		1389	priority than the default, and which should only process data when no
		1390	other events are pending:
		1391
		1392	ev_idle idle; // actual processing watcher
		1393	ev_io io; // actual event watcher
		1394
		1395	static void
		1396	io_cb (EV_P_ ev_io *w, int revents)
		1397	{
		1398	// stop the I/O watcher, we received the event, but
		1399	// are not yet ready to handle it.
		1400	ev_io_stop (EV_A_ w);
		1401
		1402	// start the idle watcher to ahndle the actual event.
		1403	// it will not be executed as long as other watchers
		1404	// with the default priority are receiving events.
		1405	ev_idle_start (EV_A_ &idle);
		1406	}
		1407
		1408	static void
		1409	idle_cb (EV_P_ ev_idle *w, int revents)
		1410	{
		1411	// actual processing
		1412	read (STDIN_FILENO, ...);
		1413
		1414	// have to start the I/O watcher again, as
		1415	// we have handled the event
		1416	ev_io_start (EV_P_ &io);
		1417	}
		1418
		1419	// initialisation
		1420	ev_idle_init (&idle, idle_cb);
		1421	ev_io_init (&io, io_cb, STDIN_FILENO, EV_READ);
		1422	ev_io_start (EV_DEFAULT_ &io);
		1423
		1424	In the "real" world, it might also be beneficial to start a timer, so that
		1425	low-priority connections can not be locked out forever under load. This
		1426	enables your program to keep a lower latency for important connections
		1427	during short periods of high load, while not completely locking out less
		1428	important ones.
1189		1429
1190		1430
1191	=head1 WATCHER TYPES	1431	=head1 WATCHER TYPES
1192		1432
1193	This section describes each watcher in detail, but will not repeat	1433	This section describes each watcher in detail, but will not repeat
…		…
1219	descriptors to non-blocking mode is also usually a good idea (but not	1459	descriptors to non-blocking mode is also usually a good idea (but not
1220	required if you know what you are doing).	1460	required if you know what you are doing).
1221		1461
1222	If you cannot use non-blocking mode, then force the use of a	1462	If you cannot use non-blocking mode, then force the use of a
1223	known-to-be-good backend (at the time of this writing, this includes only	1463	known-to-be-good backend (at the time of this writing, this includes only
1224	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>).	1464	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file
		1465	descriptors for which non-blocking operation makes no sense (such as
		1466	files) - libev doesn't guarentee any specific behaviour in that case.
1225		1467
1226	Another thing you have to watch out for is that it is quite easy to	1468	Another thing you have to watch out for is that it is quite easy to
1227	receive "spurious" readiness notifications, that is your callback might	1469	receive "spurious" readiness notifications, that is your callback might
1228	be called with C<EV_READ> but a subsequent C<read>(2) will actually block	1470	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
1229	because there is no data. Not only are some backends known to create a	1471	because there is no data. Not only are some backends known to create a
…		…
1350	year, it will still time out after (roughly) one hour. "Roughly" because	1592	year, it will still time out after (roughly) one hour. "Roughly" because
1351	detecting time jumps is hard, and some inaccuracies are unavoidable (the	1593	detecting time jumps is hard, and some inaccuracies are unavoidable (the
1352	monotonic clock option helps a lot here).	1594	monotonic clock option helps a lot here).
1353		1595
1354	The callback is guaranteed to be invoked only I<after> its timeout has	1596	The callback is guaranteed to be invoked only I<after> its timeout has
1355	passed. If multiple timers become ready during the same loop iteration	1597	passed (not I<at>, so on systems with very low-resolution clocks this
1356	then the ones with earlier time-out values are invoked before ones with	1598	might introduce a small delay). If multiple timers become ready during the
1357	later time-out values (but this is no longer true when a callback calls	1599	same loop iteration then the ones with earlier time-out values are invoked
1358	C<ev_loop> recursively).	1600	before ones of the same priority with later time-out values (but this is
		1601	no longer true when a callback calls C<ev_loop> recursively).
1359		1602
1360	=head3 Be smart about timeouts	1603	=head3 Be smart about timeouts
1361		1604
1362	Many real-world problems involve some kind of timeout, usually for error	1605	Many real-world problems involve some kind of timeout, usually for error
1363	recovery. A typical example is an HTTP request - if the other side hangs,	1606	recovery. A typical example is an HTTP request - if the other side hangs,
…		…
1407	C<after> argument to C<ev_timer_set>, and only ever use the C<repeat>	1650	C<after> argument to C<ev_timer_set>, and only ever use the C<repeat>
1408	member and C<ev_timer_again>.	1651	member and C<ev_timer_again>.
1409		1652
1410	At start:	1653	At start:
1411		1654
1412	ev_timer_init (timer, callback);	1655	ev_init (timer, callback);
1413	timer->repeat = 60.;	1656	timer->repeat = 60.;
1414	ev_timer_again (loop, timer);	1657	ev_timer_again (loop, timer);
1415		1658
1416	Each time there is some activity:	1659	Each time there is some activity:
1417		1660
…		…
1479		1722
1480	To start the timer, simply initialise the watcher and set C<last_activity>	1723	To start the timer, simply initialise the watcher and set C<last_activity>
1481	to the current time (meaning we just have some activity :), then call the	1724	to the current time (meaning we just have some activity :), then call the
1482	callback, which will "do the right thing" and start the timer:	1725	callback, which will "do the right thing" and start the timer:
1483		1726
1484	ev_timer_init (timer, callback);	1727	ev_init (timer, callback);
1485	last_activity = ev_now (loop);	1728	last_activity = ev_now (loop);
1486	callback (loop, timer, EV_TIMEOUT);	1729	callback (loop, timer, EV_TIMEOUT);
1487		1730
1488	And when there is some activity, simply store the current time in	1731	And when there is some activity, simply store the current time in
1489	C<last_activity>, no libev calls at all:	1732	C<last_activity>, no libev calls at all:
…		…
1550		1793
1551	If the event loop is suspended for a long time, you can also force an	1794	If the event loop is suspended for a long time, you can also force an
1552	update of the time returned by C<ev_now ()> by calling C<ev_now_update	1795	update of the time returned by C<ev_now ()> by calling C<ev_now_update
1553	()>.	1796	()>.
1554		1797
		1798	=head3 The special problems of suspended animation
		1799
		1800	When you leave the server world it is quite customary to hit machines that
		1801	can suspend/hibernate - what happens to the clocks during such a suspend?
		1802
		1803	Some quick tests made with a Linux 2.6.28 indicate that a suspend freezes
		1804	all processes, while the clocks (C<times>, C<CLOCK_MONOTONIC>) continue
		1805	to run until the system is suspended, but they will not advance while the
		1806	system is suspended. That means, on resume, it will be as if the program
		1807	was frozen for a few seconds, but the suspend time will not be counted
		1808	towards C<ev_timer> when a monotonic clock source is used. The real time
		1809	clock advanced as expected, but if it is used as sole clocksource, then a
		1810	long suspend would be detected as a time jump by libev, and timers would
		1811	be adjusted accordingly.
		1812
		1813	I would not be surprised to see different behaviour in different between
		1814	operating systems, OS versions or even different hardware.
		1815
		1816	The other form of suspend (job control, or sending a SIGSTOP) will see a
		1817	time jump in the monotonic clocks and the realtime clock. If the program
		1818	is suspended for a very long time, and monotonic clock sources are in use,
		1819	then you can expect C<ev_timer>s to expire as the full suspension time
		1820	will be counted towards the timers. When no monotonic clock source is in
		1821	use, then libev will again assume a timejump and adjust accordingly.
		1822
		1823	It might be beneficial for this latter case to call C<ev_suspend>
		1824	and C<ev_resume> in code that handles C<SIGTSTP>, to at least get
		1825	deterministic behaviour in this case (you can do nothing against
		1826	C<SIGSTOP>).
		1827
1555	=head3 Watcher-Specific Functions and Data Members	1828	=head3 Watcher-Specific Functions and Data Members
1556		1829
1557	=over 4	1830	=over 4
1558		1831
1559	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	1832	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
…		…
1582	If the timer is started but non-repeating, stop it (as if it timed out).	1855	If the timer is started but non-repeating, stop it (as if it timed out).
1583		1856
1584	If the timer is repeating, either start it if necessary (with the	1857	If the timer is repeating, either start it if necessary (with the
1585	C<repeat> value), or reset the running timer to the C<repeat> value.	1858	C<repeat> value), or reset the running timer to the C<repeat> value.
1586		1859
1587	This sounds a bit complicated, see "Be smart about timeouts", above, for a	1860	This sounds a bit complicated, see L<Be smart about timeouts>, above, for a
1588	usage example.	1861	usage example.
		1862
		1863	=item ev_tstamp ev_timer_remaining (loop, ev_timer *)
		1864
		1865	Returns the remaining time until a timer fires. If the timer is active,
		1866	then this time is relative to the current event loop time, otherwise it's
		1867	the timeout value currently configured.
		1868
		1869	That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns
		1870	C<5>. When the timer is started and one second passes, C<ev_timer_remain>
		1871	will return C<4>. When the timer expires and is restarted, it will return
		1872	roughly C<7> (likely slightly less as callback invocation takes some time,
		1873	too), and so on.
1589		1874
1590	=item ev_tstamp repeat [read-write]	1875	=item ev_tstamp repeat [read-write]
1591		1876
1592	The current C<repeat> value. Will be used each time the watcher times out	1877	The current C<repeat> value. Will be used each time the watcher times out
1593	or C<ev_timer_again> is called, and determines the next timeout (if any),	1878	or C<ev_timer_again> is called, and determines the next timeout (if any),
…		…
1829	Signal watchers will trigger an event when the process receives a specific	2114	Signal watchers will trigger an event when the process receives a specific
1830	signal one or more times. Even though signals are very asynchronous, libev	2115	signal one or more times. Even though signals are very asynchronous, libev
1831	will try it's best to deliver signals synchronously, i.e. as part of the	2116	will try it's best to deliver signals synchronously, i.e. as part of the
1832	normal event processing, like any other event.	2117	normal event processing, like any other event.
1833		2118
1834	If you want signals asynchronously, just use C<sigaction> as you would	2119	If you want signals to be delivered truly asynchronously, just use
1835	do without libev and forget about sharing the signal. You can even use	2120	C<sigaction> as you would do without libev and forget about sharing
1836	C<ev_async> from a signal handler to synchronously wake up an event loop.	2121	the signal. You can even use C<ev_async> from a signal handler to
		2122	synchronously wake up an event loop.
1837		2123
1838	You can configure as many watchers as you like per signal. Only when the	2124	You can configure as many watchers as you like for the same signal, but
		2125	only within the same loop, i.e. you can watch for C<SIGINT> in your
		2126	default loop and for C<SIGIO> in another loop, but you cannot watch for
		2127	C<SIGINT> in both the default loop and another loop at the same time. At
		2128	the moment, C<SIGCHLD> is permanently tied to the default loop.
		2129
1839	first watcher gets started will libev actually register a signal handler	2130	When the first watcher gets started will libev actually register something
1840	with the kernel (thus it coexists with your own signal handlers as long as	2131	with the kernel (thus it coexists with your own signal handlers as long as
1841	you don't register any with libev for the same signal). Similarly, when	2132	you don't register any with libev for the same signal).
1842	the last signal watcher for a signal is stopped, libev will reset the
1843	signal handler to SIG_DFL (regardless of what it was set to before).
1844		2133
1845	If possible and supported, libev will install its handlers with	2134	If possible and supported, libev will install its handlers with
1846	C<SA_RESTART> behaviour enabled, so system calls should not be unduly	2135	C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should
1847	interrupted. If you have a problem with system calls getting interrupted by	2136	not be unduly interrupted. If you have a problem with system calls getting
1848	signals you can block all signals in an C<ev_check> watcher and unblock	2137	interrupted by signals you can block all signals in an C<ev_check> watcher
1849	them in an C<ev_prepare> watcher.	2138	and unblock them in an C<ev_prepare> watcher.
		2139
		2140	=head3 The special problem of inheritance over fork/execve/pthread_create
		2141
		2142	Both the signal mask (C<sigprocmask>) and the signal disposition
		2143	(C<sigaction>) are unspecified after starting a signal watcher (and after
		2144	stopping it again), that is, libev might or might not block the signal,
		2145	and might or might not set or restore the installed signal handler.
		2146
		2147	While this does not matter for the signal disposition (libev never
		2148	sets signals to C<SIG_IGN>, so handlers will be reset to C<SIG_DFL> on
		2149	C<execve>), this matters for the signal mask: many programs do not expect
		2150	certain signals to be blocked.
		2151
		2152	This means that before calling C<exec> (from the child) you should reset
		2153	the signal mask to whatever "default" you expect (all clear is a good
		2154	choice usually).
		2155
		2156	The simplest way to ensure that the signal mask is reset in the child is
		2157	to install a fork handler with C<pthread_atfork> that resets it. That will
		2158	catch fork calls done by libraries (such as the libc) as well.
		2159
		2160	In current versions of libev, the signal will not be blocked indefinitely
		2161	unless you use the C<signalfd> API (C<EV_SIGNALFD>). While this reduces
		2162	the window of opportunity for problems, it will not go away, as libev
		2163	I<has> to modify the signal mask, at least temporarily.
		2164
		2165	So I can't stress this enough I<if you do not reset your signal mask
		2166	when you expect it to be empty, you have a race condition in your
		2167	program>. This is not a libev-specific thing, this is true for most event
		2168	libraries.
1850		2169
1851	=head3 Watcher-Specific Functions and Data Members	2170	=head3 Watcher-Specific Functions and Data Members
1852		2171
1853	=over 4	2172	=over 4
1854		2173
…		…
1886	some child status changes (most typically when a child of yours dies or	2205	some child status changes (most typically when a child of yours dies or
1887	exits). It is permissible to install a child watcher I<after> the child	2206	exits). It is permissible to install a child watcher I<after> the child
1888	has been forked (which implies it might have already exited), as long	2207	has been forked (which implies it might have already exited), as long
1889	as the event loop isn't entered (or is continued from a watcher), i.e.,	2208	as the event loop isn't entered (or is continued from a watcher), i.e.,
1890	forking and then immediately registering a watcher for the child is fine,	2209	forking and then immediately registering a watcher for the child is fine,
1891	but forking and registering a watcher a few event loop iterations later is	2210	but forking and registering a watcher a few event loop iterations later or
1892	not.	2211	in the next callback invocation is not.
1893		2212
1894	Only the default event loop is capable of handling signals, and therefore	2213	Only the default event loop is capable of handling signals, and therefore
1895	you can only register child watchers in the default event loop.	2214	you can only register child watchers in the default event loop.
1896		2215
		2216	Due to some design glitches inside libev, child watchers will always be
		2217	handled at maximum priority (their priority is set to C<EV_MAXPRI> by
		2218	libev)
		2219
1897	=head3 Process Interaction	2220	=head3 Process Interaction
1898		2221
1899	Libev grabs C<SIGCHLD> as soon as the default event loop is	2222	Libev grabs C<SIGCHLD> as soon as the default event loop is
1900	initialised. This is necessary to guarantee proper behaviour even if	2223	initialised. This is necessary to guarantee proper behaviour even if the
1901	the first child watcher is started after the child exits. The occurrence	2224	first child watcher is started after the child exits. The occurrence
1902	of C<SIGCHLD> is recorded asynchronously, but child reaping is done	2225	of C<SIGCHLD> is recorded asynchronously, but child reaping is done
1903	synchronously as part of the event loop processing. Libev always reaps all	2226	synchronously as part of the event loop processing. Libev always reaps all
1904	children, even ones not watched.	2227	children, even ones not watched.
1905		2228
1906	=head3 Overriding the Built-In Processing	2229	=head3 Overriding the Built-In Processing
…		…
1916	=head3 Stopping the Child Watcher	2239	=head3 Stopping the Child Watcher
1917		2240
1918	Currently, the child watcher never gets stopped, even when the	2241	Currently, the child watcher never gets stopped, even when the
1919	child terminates, so normally one needs to stop the watcher in the	2242	child terminates, so normally one needs to stop the watcher in the
1920	callback. Future versions of libev might stop the watcher automatically	2243	callback. Future versions of libev might stop the watcher automatically
1921	when a child exit is detected.	2244	when a child exit is detected (calling C<ev_child_stop> twice is not a
		2245	problem).
1922		2246
1923	=head3 Watcher-Specific Functions and Data Members	2247	=head3 Watcher-Specific Functions and Data Members
1924		2248
1925	=over 4	2249	=over 4
1926		2250
…		…
2252	// no longer anything immediate to do.	2576	// no longer anything immediate to do.
2253	}	2577	}
2254		2578
2255	ev_idle *idle_watcher = malloc (sizeof (ev_idle));	2579	ev_idle *idle_watcher = malloc (sizeof (ev_idle));
2256	ev_idle_init (idle_watcher, idle_cb);	2580	ev_idle_init (idle_watcher, idle_cb);
2257	ev_idle_start (loop, idle_cb);	2581	ev_idle_start (loop, idle_watcher);
2258		2582
2259		2583
2260	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!	2584	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!
2261		2585
2262	Prepare and check watchers are usually (but not always) used in pairs:	2586	Prepare and check watchers are usually (but not always) used in pairs:
…		…
2355	struct pollfd fds [nfd];	2679	struct pollfd fds [nfd];
2356	// actual code will need to loop here and realloc etc.	2680	// actual code will need to loop here and realloc etc.
2357	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	2681	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
2358		2682
2359	/* the callback is illegal, but won't be called as we stop during check */	2683	/* the callback is illegal, but won't be called as we stop during check */
2360	ev_timer_init (&tw, 0, timeout * 1e-3);	2684	ev_timer_init (&tw, 0, timeout * 1e-3, 0.);
2361	ev_timer_start (loop, &tw);	2685	ev_timer_start (loop, &tw);
2362		2686
2363	// create one ev_io per pollfd	2687	// create one ev_io per pollfd
2364	for (int i = 0; i < nfd; ++i)	2688	for (int i = 0; i < nfd; ++i)
2365	{	2689	{
…		…
2595	event loop blocks next and before C<ev_check> watchers are being called,	2919	event loop blocks next and before C<ev_check> watchers are being called,
2596	and only in the child after the fork. If whoever good citizen calling	2920	and only in the child after the fork. If whoever good citizen calling
2597	C<ev_default_fork> cheats and calls it in the wrong process, the fork	2921	C<ev_default_fork> cheats and calls it in the wrong process, the fork
2598	handlers will be invoked, too, of course.	2922	handlers will be invoked, too, of course.
2599		2923
		2924	=head3 The special problem of life after fork - how is it possible?
		2925
		2926	Most uses of C<fork()> consist of forking, then some simple calls to ste
		2927	up/change the process environment, followed by a call to C<exec()>. This
		2928	sequence should be handled by libev without any problems.
		2929
		2930	This changes when the application actually wants to do event handling
		2931	in the child, or both parent in child, in effect "continuing" after the
		2932	fork.
		2933
		2934	The default mode of operation (for libev, with application help to detect
		2935	forks) is to duplicate all the state in the child, as would be expected
		2936	when I<either> the parent I<or> the child process continues.
		2937
		2938	When both processes want to continue using libev, then this is usually the
		2939	wrong result. In that case, usually one process (typically the parent) is
		2940	supposed to continue with all watchers in place as before, while the other
		2941	process typically wants to start fresh, i.e. without any active watchers.
		2942
		2943	The cleanest and most efficient way to achieve that with libev is to
		2944	simply create a new event loop, which of course will be "empty", and
		2945	use that for new watchers. This has the advantage of not touching more
		2946	memory than necessary, and thus avoiding the copy-on-write, and the
		2947	disadvantage of having to use multiple event loops (which do not support
		2948	signal watchers).
		2949
		2950	When this is not possible, or you want to use the default loop for
		2951	other reasons, then in the process that wants to start "fresh", call
		2952	C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying
		2953	the default loop will "orphan" (not stop) all registered watchers, so you
		2954	have to be careful not to execute code that modifies those watchers. Note
		2955	also that in that case, you have to re-register any signal watchers.
		2956
2600	=head3 Watcher-Specific Functions and Data Members	2957	=head3 Watcher-Specific Functions and Data Members
2601		2958
2602	=over 4	2959	=over 4
2603		2960
2604	=item ev_fork_init (ev_signal *, callback)	2961	=item ev_fork_init (ev_signal *, callback)
…		…
2633	=head3 Queueing	2990	=head3 Queueing
2634		2991
2635	C<ev_async> does not support queueing of data in any way. The reason	2992	C<ev_async> does not support queueing of data in any way. The reason
2636	is that the author does not know of a simple (or any) algorithm for a	2993	is that the author does not know of a simple (or any) algorithm for a
2637	multiple-writer-single-reader queue that works in all cases and doesn't	2994	multiple-writer-single-reader queue that works in all cases and doesn't
2638	need elaborate support such as pthreads.	2995	need elaborate support such as pthreads or unportable memory access
		2996	semantics.
2639		2997
2640	That means that if you want to queue data, you have to provide your own	2998	That means that if you want to queue data, you have to provide your own
2641	queue. But at least I can tell you how to implement locking around your	2999	queue. But at least I can tell you how to implement locking around your
2642	queue:	3000	queue:
2643		3001
…		…
2801	/* doh, nothing entered */;	3159	/* doh, nothing entered */;
2802	}	3160	}
2803		3161
2804	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	3162	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
2805		3163
2806	=item ev_feed_event (struct ev_loop , watcher , int revents)
2807
2808	Feeds the given event set into the event loop, as if the specified event
2809	had happened for the specified watcher (which must be a pointer to an
2810	initialised but not necessarily started event watcher).
2811
2812	=item ev_feed_fd_event (struct ev_loop *, int fd, int revents)	3164	=item ev_feed_fd_event (loop, int fd, int revents)
2813		3165
2814	Feed an event on the given fd, as if a file descriptor backend detected	3166	Feed an event on the given fd, as if a file descriptor backend detected
2815	the given events it.	3167	the given events it.
2816		3168
2817	=item ev_feed_signal_event (struct ev_loop *loop, int signum)	3169	=item ev_feed_signal_event (loop, int signum)
2818		3170
2819	Feed an event as if the given signal occurred (C<loop> must be the default	3171	Feed an event as if the given signal occurred (C<loop> must be the default
2820	loop!).	3172	loop!).
2821		3173
2822	=back	3174	=back
…		…
2902		3254
2903	=over 4	3255	=over 4
2904		3256
2905	=item ev::TYPE::TYPE ()	3257	=item ev::TYPE::TYPE ()
2906		3258
2907	=item ev::TYPE::TYPE (struct ev_loop *)	3259	=item ev::TYPE::TYPE (loop)
2908		3260
2909	=item ev::TYPE::~TYPE	3261	=item ev::TYPE::~TYPE
2910		3262
2911	The constructor (optionally) takes an event loop to associate the watcher	3263	The constructor (optionally) takes an event loop to associate the watcher
2912	with. If it is omitted, it will use C<EV_DEFAULT>.	3264	with. If it is omitted, it will use C<EV_DEFAULT>.
…		…
2989	Example: Use a plain function as callback.	3341	Example: Use a plain function as callback.
2990		3342
2991	static void io_cb (ev::io &w, int revents) { }	3343	static void io_cb (ev::io &w, int revents) { }
2992	iow.set <io_cb> ();	3344	iow.set <io_cb> ();
2993		3345
2994	=item w->set (struct ev_loop *)	3346	=item w->set (loop)
2995		3347
2996	Associates a different C<struct ev_loop> with this watcher. You can only	3348	Associates a different C<struct ev_loop> with this watcher. You can only
2997	do this when the watcher is inactive (and not pending either).	3349	do this when the watcher is inactive (and not pending either).
2998		3350
2999	=item w->set ([arguments])	3351	=item w->set ([arguments])
…		…
3096	=item Ocaml	3448	=item Ocaml
3097		3449
3098	Erkki Seppala has written Ocaml bindings for libev, to be found at	3450	Erkki Seppala has written Ocaml bindings for libev, to be found at
3099	L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>.	3451	L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>.
3100		3452
		3453	=item Lua
		3454
		3455	Brian Maher has written a partial interface to libev
		3456	for lua (only C<ev_io> and C<ev_timer>), to be found at
		3457	L<http://github.com/brimworks/lua-ev>.
		3458
3101	=back	3459	=back
3102		3460
3103		3461
3104	=head1 MACRO MAGIC	3462	=head1 MACRO MAGIC
3105		3463
…		…
3271	keeps libev from including F<config.h>, and it also defines dummy	3629	keeps libev from including F<config.h>, and it also defines dummy
3272	implementations for some libevent functions (such as logging, which is not	3630	implementations for some libevent functions (such as logging, which is not
3273	supported). It will also not define any of the structs usually found in	3631	supported). It will also not define any of the structs usually found in
3274	F<event.h> that are not directly supported by the libev core alone.	3632	F<event.h> that are not directly supported by the libev core alone.
3275		3633
3276	In stanbdalone mode, libev will still try to automatically deduce the	3634	In standalone mode, libev will still try to automatically deduce the
3277	configuration, but has to be more conservative.	3635	configuration, but has to be more conservative.
3278		3636
3279	=item EV_USE_MONOTONIC	3637	=item EV_USE_MONOTONIC
3280		3638
3281	If defined to be C<1>, libev will try to detect the availability of the	3639	If defined to be C<1>, libev will try to detect the availability of the
…		…
3346	be used is the winsock select). This means that it will call	3704	be used is the winsock select). This means that it will call
3347	C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise,	3705	C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise,
3348	it is assumed that all these functions actually work on fds, even	3706	it is assumed that all these functions actually work on fds, even
3349	on win32. Should not be defined on non-win32 platforms.	3707	on win32. Should not be defined on non-win32 platforms.
3350		3708
3351	=item EV_FD_TO_WIN32_HANDLE	3709	=item EV_FD_TO_WIN32_HANDLE(fd)
3352		3710
3353	If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map	3711	If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map
3354	file descriptors to socket handles. When not defining this symbol (the	3712	file descriptors to socket handles. When not defining this symbol (the
3355	default), then libev will call C<_get_osfhandle>, which is usually	3713	default), then libev will call C<_get_osfhandle>, which is usually
3356	correct. In some cases, programs use their own file descriptor management,	3714	correct. In some cases, programs use their own file descriptor management,
3357	in which case they can provide this function to map fds to socket handles.	3715	in which case they can provide this function to map fds to socket handles.
		3716
		3717	=item EV_WIN32_HANDLE_TO_FD(handle)
		3718
		3719	If C<EV_SELECT_IS_WINSOCKET> then libev maps handles to file descriptors
		3720	using the standard C<_open_osfhandle> function. For programs implementing
		3721	their own fd to handle mapping, overwriting this function makes it easier
		3722	to do so. This can be done by defining this macro to an appropriate value.
		3723
		3724	=item EV_WIN32_CLOSE_FD(fd)
		3725
		3726	If programs implement their own fd to handle mapping on win32, then this
		3727	macro can be used to override the C<close> function, useful to unregister
		3728	file descriptors again. Note that the replacement function has to close
		3729	the underlying OS handle.
3358		3730
3359	=item EV_USE_POLL	3731	=item EV_USE_POLL
3360		3732
3361	If defined to be C<1>, libev will compile in support for the C<poll>(2)	3733	If defined to be C<1>, libev will compile in support for the C<poll>(2)
3362	backend. Otherwise it will be enabled on non-win32 platforms. It	3734	backend. Otherwise it will be enabled on non-win32 platforms. It
…		…
3494	defined to be C<0>, then they are not.	3866	defined to be C<0>, then they are not.
3495		3867
3496	=item EV_MINIMAL	3868	=item EV_MINIMAL
3497		3869
3498	If you need to shave off some kilobytes of code at the expense of some	3870	If you need to shave off some kilobytes of code at the expense of some
3499	speed, define this symbol to C<1>. Currently this is used to override some	3871	speed (but with the full API), define this symbol to C<1>. Currently this
3500	inlining decisions, saves roughly 30% code size on amd64. It also selects a	3872	is used to override some inlining decisions, saves roughly 30% code size
3501	much smaller 2-heap for timer management over the default 4-heap.	3873	on amd64. It also selects a much smaller 2-heap for timer management over
		3874	the default 4-heap.
		3875
		3876	You can save even more by disabling watcher types you do not need
		3877	and setting C<EV_MAXPRI> == C<EV_MINPRI>. Also, disabling C<assert>
		3878	(C<-DNDEBUG>) will usually reduce code size a lot.
		3879
		3880	Defining C<EV_MINIMAL> to C<2> will additionally reduce the core API to
		3881	provide a bare-bones event library. See C<ev.h> for details on what parts
		3882	of the API are still available, and do not complain if this subset changes
		3883	over time.
		3884
		3885	=item EV_NSIG
		3886
		3887	The highest supported signal number, +1 (or, the number of
		3888	signals): Normally, libev tries to deduce the maximum number of signals
		3889	automatically, but sometimes this fails, in which case it can be
		3890	specified. Also, using a lower number than detected (C<32> should be
		3891	good for about any system in existance) can save some memory, as libev
		3892	statically allocates some 12-24 bytes per signal number.
3502		3893
3503	=item EV_PID_HASHSIZE	3894	=item EV_PID_HASHSIZE
3504		3895
3505	C<ev_child> watchers use a small hash table to distribute workload by	3896	C<ev_child> watchers use a small hash table to distribute workload by
3506	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more	3897	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
…		…
3692	default loop and triggering an C<ev_async> watcher from the default loop	4083	default loop and triggering an C<ev_async> watcher from the default loop
3693	watcher callback into the event loop interested in the signal.	4084	watcher callback into the event loop interested in the signal.
3694		4085
3695	=back	4086	=back
3696		4087
		4088	=head4 THREAD LOCKING EXAMPLE
		4089
		4090	Here is a fictitious example of how to run an event loop in a different
		4091	thread than where callbacks are being invoked and watchers are
		4092	created/added/removed.
		4093
		4094	For a real-world example, see the C<EV::Loop::Async> perl module,
		4095	which uses exactly this technique (which is suited for many high-level
		4096	languages).
		4097
		4098	The example uses a pthread mutex to protect the loop data, a condition
		4099	variable to wait for callback invocations, an async watcher to notify the
		4100	event loop thread and an unspecified mechanism to wake up the main thread.
		4101
		4102	First, you need to associate some data with the event loop:
		4103
		4104	typedef struct {
		4105	mutex_t lock; /* global loop lock */
		4106	ev_async async_w;
		4107	thread_t tid;
		4108	cond_t invoke_cv;
		4109	} userdata;
		4110
		4111	void prepare_loop (EV_P)
		4112	{
		4113	// for simplicity, we use a static userdata struct.
		4114	static userdata u;
		4115
		4116	ev_async_init (&u->async_w, async_cb);
		4117	ev_async_start (EV_A_ &u->async_w);
		4118
		4119	pthread_mutex_init (&u->lock, 0);
		4120	pthread_cond_init (&u->invoke_cv, 0);
		4121
		4122	// now associate this with the loop
		4123	ev_set_userdata (EV_A_ u);
		4124	ev_set_invoke_pending_cb (EV_A_ l_invoke);
		4125	ev_set_loop_release_cb (EV_A_ l_release, l_acquire);
		4126
		4127	// then create the thread running ev_loop
		4128	pthread_create (&u->tid, 0, l_run, EV_A);
		4129	}
		4130
		4131	The callback for the C<ev_async> watcher does nothing: the watcher is used
		4132	solely to wake up the event loop so it takes notice of any new watchers
		4133	that might have been added:
		4134
		4135	static void
		4136	async_cb (EV_P_ ev_async *w, int revents)
		4137	{
		4138	// just used for the side effects
		4139	}
		4140
		4141	The C<l_release> and C<l_acquire> callbacks simply unlock/lock the mutex
		4142	protecting the loop data, respectively.
		4143
		4144	static void
		4145	l_release (EV_P)
		4146	{
		4147	userdata *u = ev_userdata (EV_A);
		4148	pthread_mutex_unlock (&u->lock);
		4149	}
		4150
		4151	static void
		4152	l_acquire (EV_P)
		4153	{
		4154	userdata *u = ev_userdata (EV_A);
		4155	pthread_mutex_lock (&u->lock);
		4156	}
		4157
		4158	The event loop thread first acquires the mutex, and then jumps straight
		4159	into C<ev_loop>:
		4160
		4161	void *
		4162	l_run (void *thr_arg)
		4163	{
		4164	struct ev_loop loop = (struct ev_loop )thr_arg;
		4165
		4166	l_acquire (EV_A);
		4167	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
		4168	ev_loop (EV_A_ 0);
		4169	l_release (EV_A);
		4170
		4171	return 0;
		4172	}
		4173
		4174	Instead of invoking all pending watchers, the C<l_invoke> callback will
		4175	signal the main thread via some unspecified mechanism (signals? pipe
		4176	writes? C<Async::Interrupt>?) and then waits until all pending watchers
		4177	have been called (in a while loop because a) spurious wakeups are possible
		4178	and b) skipping inter-thread-communication when there are no pending
		4179	watchers is very beneficial):
		4180
		4181	static void
		4182	l_invoke (EV_P)
		4183	{
		4184	userdata *u = ev_userdata (EV_A);
		4185
		4186	while (ev_pending_count (EV_A))
		4187	{
		4188	wake_up_other_thread_in_some_magic_or_not_so_magic_way ();
		4189	pthread_cond_wait (&u->invoke_cv, &u->lock);
		4190	}
		4191	}
		4192
		4193	Now, whenever the main thread gets told to invoke pending watchers, it
		4194	will grab the lock, call C<ev_invoke_pending> and then signal the loop
		4195	thread to continue:
		4196
		4197	static void
		4198	real_invoke_pending (EV_P)
		4199	{
		4200	userdata *u = ev_userdata (EV_A);
		4201
		4202	pthread_mutex_lock (&u->lock);
		4203	ev_invoke_pending (EV_A);
		4204	pthread_cond_signal (&u->invoke_cv);
		4205	pthread_mutex_unlock (&u->lock);
		4206	}
		4207
		4208	Whenever you want to start/stop a watcher or do other modifications to an
		4209	event loop, you will now have to lock:
		4210
		4211	ev_timer timeout_watcher;
		4212	userdata *u = ev_userdata (EV_A);
		4213
		4214	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
		4215
		4216	pthread_mutex_lock (&u->lock);
		4217	ev_timer_start (EV_A_ &timeout_watcher);
		4218	ev_async_send (EV_A_ &u->async_w);
		4219	pthread_mutex_unlock (&u->lock);
		4220
		4221	Note that sending the C<ev_async> watcher is required because otherwise
		4222	an event loop currently blocking in the kernel will have no knowledge
		4223	about the newly added timer. By waking up the loop it will pick up any new
		4224	watchers in the next event loop iteration.
		4225
3697	=head3 COROUTINES	4226	=head3 COROUTINES
3698		4227
3699	Libev is very accommodating to coroutines ("cooperative threads"):	4228	Libev is very accommodating to coroutines ("cooperative threads"):
3700	libev fully supports nesting calls to its functions from different	4229	libev fully supports nesting calls to its functions from different
3701	coroutines (e.g. you can call C<ev_loop> on the same loop from two	4230	coroutines (e.g. you can call C<ev_loop> on the same loop from two
3702	different coroutines, and switch freely between both coroutines running the	4231	different coroutines, and switch freely between both coroutines running
3703	loop, as long as you don't confuse yourself). The only exception is that	4232	the loop, as long as you don't confuse yourself). The only exception is
3704	you must not do this from C<ev_periodic> reschedule callbacks.	4233	that you must not do this from C<ev_periodic> reschedule callbacks.
3705		4234
3706	Care has been taken to ensure that libev does not keep local state inside	4235	Care has been taken to ensure that libev does not keep local state inside
3707	C<ev_loop>, and other calls do not usually allow for coroutine switches as	4236	C<ev_loop>, and other calls do not usually allow for coroutine switches as
3708	they do not call any callbacks.	4237	they do not call any callbacks.
3709		4238
…		…
3786	way (note also that glib is the slowest event library known to man).	4315	way (note also that glib is the slowest event library known to man).
3787		4316
3788	There is no supported compilation method available on windows except	4317	There is no supported compilation method available on windows except
3789	embedding it into other applications.	4318	embedding it into other applications.
3790		4319
		4320	Sensible signal handling is officially unsupported by Microsoft - libev
		4321	tries its best, but under most conditions, signals will simply not work.
		4322
3791	Not a libev limitation but worth mentioning: windows apparently doesn't	4323	Not a libev limitation but worth mentioning: windows apparently doesn't
3792	accept large writes: instead of resulting in a partial write, windows will	4324	accept large writes: instead of resulting in a partial write, windows will
3793	either accept everything or return C<ENOBUFS> if the buffer is too large,	4325	either accept everything or return C<ENOBUFS> if the buffer is too large,
3794	so make sure you only write small amounts into your sockets (less than a	4326	so make sure you only write small amounts into your sockets (less than a
3795	megabyte seems safe, but this apparently depends on the amount of memory	4327	megabyte seems safe, but this apparently depends on the amount of memory
…		…
3799	the abysmal performance of winsockets, using a large number of sockets	4331	the abysmal performance of winsockets, using a large number of sockets
3800	is not recommended (and not reasonable). If your program needs to use	4332	is not recommended (and not reasonable). If your program needs to use
3801	more than a hundred or so sockets, then likely it needs to use a totally	4333	more than a hundred or so sockets, then likely it needs to use a totally
3802	different implementation for windows, as libev offers the POSIX readiness	4334	different implementation for windows, as libev offers the POSIX readiness
3803	notification model, which cannot be implemented efficiently on windows	4335	notification model, which cannot be implemented efficiently on windows
3804	(Microsoft monopoly games).	4336	(due to Microsoft monopoly games).
3805		4337
3806	A typical way to use libev under windows is to embed it (see the embedding	4338	A typical way to use libev under windows is to embed it (see the embedding
3807	section for details) and use the following F<evwrap.h> header file instead	4339	section for details) and use the following F<evwrap.h> header file instead
3808	of F<ev.h>:	4340	of F<ev.h>:
3809		4341
…		…
3845		4377
3846	Early versions of winsocket's select only supported waiting for a maximum	4378	Early versions of winsocket's select only supported waiting for a maximum
3847	of C<64> handles (probably owning to the fact that all windows kernels	4379	of C<64> handles (probably owning to the fact that all windows kernels
3848	can only wait for C<64> things at the same time internally; Microsoft	4380	can only wait for C<64> things at the same time internally; Microsoft
3849	recommends spawning a chain of threads and wait for 63 handles and the	4381	recommends spawning a chain of threads and wait for 63 handles and the
3850	previous thread in each. Great).	4382	previous thread in each. Sounds great!).
3851		4383
3852	Newer versions support more handles, but you need to define C<FD_SETSIZE>	4384	Newer versions support more handles, but you need to define C<FD_SETSIZE>
3853	to some high number (e.g. C<2048>) before compiling the winsocket select	4385	to some high number (e.g. C<2048>) before compiling the winsocket select
3854	call (which might be in libev or elsewhere, for example, perl does its own	4386	call (which might be in libev or elsewhere, for example, perl and many
3855	select emulation on windows).	4387	other interpreters do their own select emulation on windows).
3856		4388
3857	Another limit is the number of file descriptors in the Microsoft runtime	4389	Another limit is the number of file descriptors in the Microsoft runtime
3858	libraries, which by default is C<64> (there must be a hidden I<64> fetish	4390	libraries, which by default is C<64> (there must be a hidden I<64>
3859	or something like this inside Microsoft). You can increase this by calling	4391	fetish or something like this inside Microsoft). You can increase this
3860	C<_setmaxstdio>, which can increase this limit to C<2048> (another	4392	by calling C<_setmaxstdio>, which can increase this limit to C<2048>
3861	arbitrary limit), but is broken in many versions of the Microsoft runtime	4393	(another arbitrary limit), but is broken in many versions of the Microsoft
3862	libraries.
3863
3864	This might get you to about C<512> or C<2048> sockets (depending on	4394	runtime libraries. This might get you to about C<512> or C<2048> sockets
3865	windows version and/or the phase of the moon). To get more, you need to	4395	(depending on windows version and/or the phase of the moon). To get more,
3866	wrap all I/O functions and provide your own fd management, but the cost of	4396	you need to wrap all I/O functions and provide your own fd management, but
3867	calling select (O(n²)) will likely make this unworkable.	4397	the cost of calling select (O(n²)) will likely make this unworkable.
3868		4398
3869	=back	4399	=back
3870		4400
3871	=head2 PORTABILITY REQUIREMENTS	4401	=head2 PORTABILITY REQUIREMENTS
3872		4402
…		…
3915	=item C<double> must hold a time value in seconds with enough accuracy	4445	=item C<double> must hold a time value in seconds with enough accuracy
3916		4446
3917	The type C<double> is used to represent timestamps. It is required to	4447	The type C<double> is used to represent timestamps. It is required to
3918	have at least 51 bits of mantissa (and 9 bits of exponent), which is good	4448	have at least 51 bits of mantissa (and 9 bits of exponent), which is good
3919	enough for at least into the year 4000. This requirement is fulfilled by	4449	enough for at least into the year 4000. This requirement is fulfilled by
3920	implementations implementing IEEE 754 (basically all existing ones).	4450	implementations implementing IEEE 754, which is basically all existing
		4451	ones. With IEEE 754 doubles, you get microsecond accuracy until at least
		4452	2200.
3921		4453
3922	=back	4454	=back
3923		4455
3924	If you know of other additional requirements drop me a note.	4456	If you know of other additional requirements drop me a note.
3925		4457
…		…
3993	involves iterating over all running async watchers or all signal numbers.	4525	involves iterating over all running async watchers or all signal numbers.
3994		4526
3995	=back	4527	=back
3996		4528
3997		4529
		4530	=head1 GLOSSARY
		4531
		4532	=over 4
		4533
		4534	=item active
		4535
		4536	A watcher is active as long as it has been started (has been attached to
		4537	an event loop) but not yet stopped (disassociated from the event loop).
		4538
		4539	=item application
		4540
		4541	In this document, an application is whatever is using libev.
		4542
		4543	=item callback
		4544
		4545	The address of a function that is called when some event has been
		4546	detected. Callbacks are being passed the event loop, the watcher that
		4547	received the event, and the actual event bitset.
		4548
		4549	=item callback invocation
		4550
		4551	The act of calling the callback associated with a watcher.
		4552
		4553	=item event
		4554
		4555	A change of state of some external event, such as data now being available
		4556	for reading on a file descriptor, time having passed or simply not having
		4557	any other events happening anymore.
		4558
		4559	In libev, events are represented as single bits (such as C<EV_READ> or
		4560	C<EV_TIMEOUT>).
		4561
		4562	=item event library
		4563
		4564	A software package implementing an event model and loop.
		4565
		4566	=item event loop
		4567
		4568	An entity that handles and processes external events and converts them
		4569	into callback invocations.
		4570
		4571	=item event model
		4572
		4573	The model used to describe how an event loop handles and processes
		4574	watchers and events.
		4575
		4576	=item pending
		4577
		4578	A watcher is pending as soon as the corresponding event has been detected,
		4579	and stops being pending as soon as the watcher will be invoked or its
		4580	pending status is explicitly cleared by the application.
		4581
		4582	A watcher can be pending, but not active. Stopping a watcher also clears
		4583	its pending status.
		4584
		4585	=item real time
		4586
		4587	The physical time that is observed. It is apparently strictly monotonic :)
		4588
		4589	=item wall-clock time
		4590
		4591	The time and date as shown on clocks. Unlike real time, it can actually
		4592	be wrong and jump forwards and backwards, e.g. when the you adjust your
		4593	clock.
		4594
		4595	=item watcher
		4596
		4597	A data structure that describes interest in certain events. Watchers need
		4598	to be started (attached to an event loop) before they can receive events.
		4599
		4600	=item watcher invocation
		4601
		4602	The act of calling the callback associated with a watcher.
		4603
		4604	=back
		4605
3998	=head1 AUTHOR	4606	=head1 AUTHOR
3999		4607
4000	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson.	4608	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson.
4001		4609

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Comparing libev/ev.pod (file contents):
Revision 1.231 by root, Wed Apr 15 19:35:53 2009 UTC vs.
Revision 1.277 by root, Thu Dec 31 06:50:17 2009 UTC