[ViewVC] Diff of: cvs/libev/ev.pod

Comparing libev/ev.pod (file contents):
Revision 1.231 by root, Wed Apr 15 19:35:53 2009 UTC vs.
Revision 1.278 by root, Thu Dec 31 06:59:47 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 it both faster and might make
		380	it possible to get the queued signal data. It can also simplify signal
		381	handling with threads, as long as you properly block signals in your
		382	threads that are not interested in handling them.
		383
		384	Signalfd will not be used by default as this changes your signal mask, and
		385	there are a lot of shoddy libraries and programs (glib's threadpool for
		386	example) that can't properly initialise their signal masks.
		387
355	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	388	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
356		389
357	This is your standard select(2) backend. Not I<completely> standard, as	390	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,	391	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	392	but if that fails, expect a fairly low limit on the number of fds when
…		…
382		415
383	This backend maps C<EV_READ> to C<POLLIN \| POLLERR \| POLLHUP>, and	416	This backend maps C<EV_READ> to C<POLLIN \| POLLERR \| POLLHUP>, and
384	C<EV_WRITE> to C<POLLOUT \| POLLERR \| POLLHUP>.	417	C<EV_WRITE> to C<POLLOUT \| POLLERR \| POLLHUP>.
385		418
386	=item C<EVBACKEND_EPOLL> (value 4, Linux)	419	=item C<EVBACKEND_EPOLL> (value 4, Linux)
		420
		421	Use the linux-specific epoll(7) interface (for both pre- and post-2.6.9
		422	kernels).
387		423
388	For few fds, this backend is a bit little slower than poll and select,	424	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	425	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),	426	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).	427	epoll scales either O(1) or O(active_fds).
…		…
506		542
507	It is definitely not recommended to use this flag.	543	It is definitely not recommended to use this flag.
508		544
509	=back	545	=back
510		546
511	If one or more of these are or'ed into the flags value, then only these	547	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	548	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.	549	here). If none are specified, all backends in C<ev_recommended_backends
		550	()> will be tried.
514		551
515	Example: This is the most typical usage.	552	Example: This is the most typical usage.
516		553
517	if (!ev_default_loop (0))	554	if (!ev_default_loop (0))
518	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");	555	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
…		…
561	as signal and child watchers) would need to be stopped manually.	598	as signal and child watchers) would need to be stopped manually.
562		599
563	In general it is not advisable to call this function except in the	600	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	601	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	602	pipe fds. If you need dynamically allocated loops it is better to use
566	C<ev_loop_new> and C<ev_loop_destroy>).	603	C<ev_loop_new> and C<ev_loop_destroy>.
567		604
568	=item ev_loop_destroy (loop)	605	=item ev_loop_destroy (loop)
569		606
570	Like C<ev_default_destroy>, but destroys an event loop created by an	607	Like C<ev_default_destroy>, but destroys an event loop created by an
571	earlier call to C<ev_loop_new>.	608	earlier call to C<ev_loop_new>.
…		…
609		646
610	This value can sometimes be useful as a generation counter of sorts (it	647	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	648	"ticks" the number of loop iterations), as it roughly corresponds with
612	C<ev_prepare> and C<ev_check> calls.	649	C<ev_prepare> and C<ev_check> calls.
613		650
		651	=item unsigned int ev_loop_depth (loop)
		652
		653	Returns the number of times C<ev_loop> was entered minus the number of
		654	times C<ev_loop> was exited, in other words, the recursion depth.
		655
		656	Outside C<ev_loop>, this number is zero. In a callback, this number is
		657	C<1>, unless C<ev_loop> was invoked recursively (or from another thread),
		658	in which case it is higher.
		659
		660	Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread
		661	etc.), doesn't count as exit.
		662
614	=item unsigned int ev_backend (loop)	663	=item unsigned int ev_backend (loop)
615		664
616	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	665	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
617	use.	666	use.
618		667
…		…
632		681
633	This function is rarely useful, but when some event callback runs for a	682	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	683	very long time without entering the event loop, updating libev's idea of
635	the current time is a good idea.	684	the current time is a good idea.
636		685
637	See also "The special problem of time updates" in the C<ev_timer> section.	686	See also L<The special problem of time updates> in the C<ev_timer> section.
638		687
639	=item ev_suspend (loop)	688	=item ev_suspend (loop)
640		689
641	=item ev_resume (loop)	690	=item ev_resume (loop)
642		691
…		…
663	event loop time (see C<ev_now_update>).	712	event loop time (see C<ev_now_update>).
664		713
665	=item ev_loop (loop, int flags)	714	=item ev_loop (loop, int flags)
666		715
667	Finally, this is it, the event handler. This function usually is called	716	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	717	after you have initialised all your watchers and you want to start
669	events.	718	handling events.
670		719
671	If the flags argument is specified as C<0>, it will not return until	720	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.	721	either no event watchers are active anymore or C<ev_unloop> was called.
673		722
674	Please note that an explicit C<ev_unloop> is usually better than	723	Please note that an explicit C<ev_unloop> is usually better than
…		…
748		797
749	Ref/unref can be used to add or remove a reference count on the event	798	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	799	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.	800	count is nonzero, C<ev_loop> will not return on its own.
752		801
753	If you have a watcher you never unregister that should not keep C<ev_loop>	802	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	803	unregister, but that nevertheless should not keep C<ev_loop> from
		804	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>
755	stopping it.	805	before stopping it.
756		806
757	As an example, libev itself uses this for its internal signal pipe: It	807	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	808	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	809	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	810	excellent way to do this for generic recurring timers or from within
…		…
799		849
800	By setting a higher I<io collect interval> you allow libev to spend more	850	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,	851	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	852	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	853	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.	854	introduce an additional C<ev_sleep ()> call into most loop iterations. The
		855	sleep time ensures that libev will not poll for I/O events more often then
		856	once per this interval, on average.
805		857
806	Likewise, by setting a higher I<timeout collect interval> you allow libev	858	Likewise, by setting a higher I<timeout collect interval> you allow libev
807	to spend more time collecting timeouts, at the expense of increased	859	to spend more time collecting timeouts, at the expense of increased
808	latency/jitter/inexactness (the watcher callback will be called	860	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	861	later). C<ev_io> watchers will not be affected. Setting this to a non-null
…		…
811		863
812	Many (busy) programs can usually benefit by setting the I/O collect	864	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	865	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	866	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>,	867	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.	868	as this approaches the timing granularity of most systems. Note that if
		869	you do transactions with the outside world and you can't increase the
		870	parallelity, then this setting will limit your transaction rate (if you
		871	need to poll once per transaction and the I/O collect interval is 0.01,
		872	then you can't do more than 100 transations per second).
817		873
818	Setting the I<timeout collect interval> can improve the opportunity for	874	Setting the I<timeout collect interval> can improve the opportunity for
819	saving power, as the program will "bundle" timer callback invocations that	875	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	876	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	877	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	878	reduce iterations/wake-ups is to use C<ev_periodic> watchers and make sure
823	they fire on, say, one-second boundaries only.	879	they fire on, say, one-second boundaries only.
		880
		881	Example: we only need 0.1s timeout granularity, and we wish not to poll
		882	more often than 100 times per second:
		883
		884	ev_set_timeout_collect_interval (EV_DEFAULT_UC_ 0.1);
		885	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);
		886
		887	=item ev_invoke_pending (loop)
		888
		889	This call will simply invoke all pending watchers while resetting their
		890	pending state. Normally, C<ev_loop> does this automatically when required,
		891	but when overriding the invoke callback this call comes handy.
		892
		893	=item int ev_pending_count (loop)
		894
		895	Returns the number of pending watchers - zero indicates that no watchers
		896	are pending.
		897
		898	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))
		899
		900	This overrides the invoke pending functionality of the loop: Instead of
		901	invoking all pending watchers when there are any, C<ev_loop> will call
		902	this callback instead. This is useful, for example, when you want to
		903	invoke the actual watchers inside another context (another thread etc.).
		904
		905	If you want to reset the callback, use C<ev_invoke_pending> as new
		906	callback.
		907
		908	=item ev_set_loop_release_cb (loop, void (release)(EV_P), void (acquire)(EV_P))
		909
		910	Sometimes you want to share the same loop between multiple threads. This
		911	can be done relatively simply by putting mutex_lock/unlock calls around
		912	each call to a libev function.
		913
		914	However, C<ev_loop> can run an indefinite time, so it is not feasible to
		915	wait for it to return. One way around this is to wake up the loop via
		916	C<ev_unloop> and C<av_async_send>, another way is to set these I<release>
		917	and I<acquire> callbacks on the loop.
		918
		919	When set, then C<release> will be called just before the thread is
		920	suspended waiting for new events, and C<acquire> is called just
		921	afterwards.
		922
		923	Ideally, C<release> will just call your mutex_unlock function, and
		924	C<acquire> will just call the mutex_lock function again.
		925
		926	While event loop modifications are allowed between invocations of
		927	C<release> and C<acquire> (that's their only purpose after all), no
		928	modifications done will affect the event loop, i.e. adding watchers will
		929	have no effect on the set of file descriptors being watched, or the time
		930	waited. Use an C<ev_async> watcher to wake up C<ev_loop> when you want it
		931	to take note of any changes you made.
		932
		933	In theory, threads executing C<ev_loop> will be async-cancel safe between
		934	invocations of C<release> and C<acquire>.
		935
		936	See also the locking example in the C<THREADS> section later in this
		937	document.
		938
		939	=item ev_set_userdata (loop, void *data)
		940
		941	=item ev_userdata (loop)
		942
		943	Set and retrieve a single C<void *> associated with a loop. When
		944	C<ev_set_userdata> has never been called, then C<ev_userdata> returns
		945	C<0.>
		946
		947	These two functions can be used to associate arbitrary data with a loop,
		948	and are intended solely for the C<invoke_pending_cb>, C<release> and
		949	C<acquire> callbacks described above, but of course can be (ab-)used for
		950	any other purpose as well.
824		951
825	=item ev_loop_verify (loop)	952	=item ev_loop_verify (loop)
826		953
827	This function only does something when C<EV_VERIFY> support has been	954	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	955	compiled in, which is the default for non-minimal builds. It tries to go
…		…
1005		1132
1006	ev_io w;	1133	ev_io w;
1007	ev_init (&w, my_cb);	1134	ev_init (&w, my_cb);
1008	ev_io_set (&w, STDIN_FILENO, EV_READ);	1135	ev_io_set (&w, STDIN_FILENO, EV_READ);
1009		1136
1010	=item C<ev_TYPE_set> (ev_TYPE *, [args])	1137	=item C<ev_TYPE_set> (ev_TYPE *watcher, [args])
1011		1138
1012	This macro initialises the type-specific parts of a watcher. You need to	1139	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	1140	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	1141	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	1142	macro on a watcher that is active (it can be pending, however, which is a
…		…
1028		1155
1029	Example: Initialise and set an C<ev_io> watcher in one step.	1156	Example: Initialise and set an C<ev_io> watcher in one step.
1030		1157
1031	ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ);	1158	ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ);
1032		1159
1033	=item C<ev_TYPE_start> (loop , ev_TYPE watcher)	1160	=item C<ev_TYPE_start> (loop, ev_TYPE *watcher)
1034		1161
1035	Starts (activates) the given watcher. Only active watchers will receive	1162	Starts (activates) the given watcher. Only active watchers will receive
1036	events. If the watcher is already active nothing will happen.	1163	events. If the watcher is already active nothing will happen.
1037		1164
1038	Example: Start the C<ev_io> watcher that is being abused as example in this	1165	Example: Start the C<ev_io> watcher that is being abused as example in this
1039	whole section.	1166	whole section.
1040		1167
1041	ev_io_start (EV_DEFAULT_UC, &w);	1168	ev_io_start (EV_DEFAULT_UC, &w);
1042		1169
1043	=item C<ev_TYPE_stop> (loop , ev_TYPE watcher)	1170	=item C<ev_TYPE_stop> (loop, ev_TYPE *watcher)
1044		1171
1045	Stops the given watcher if active, and clears the pending status (whether	1172	Stops the given watcher if active, and clears the pending status (whether
1046	the watcher was active or not).	1173	the watcher was active or not).
1047		1174
1048	It is possible that stopped watchers are pending - for example,	1175	It is possible that stopped watchers are pending - for example,
…		…
1073	=item ev_cb_set (ev_TYPE *watcher, callback)	1200	=item ev_cb_set (ev_TYPE *watcher, callback)
1074		1201
1075	Change the callback. You can change the callback at virtually any time	1202	Change the callback. You can change the callback at virtually any time
1076	(modulo threads).	1203	(modulo threads).
1077		1204
1078	=item ev_set_priority (ev_TYPE *watcher, priority)	1205	=item ev_set_priority (ev_TYPE *watcher, int priority)
1079		1206
1080	=item int ev_priority (ev_TYPE *watcher)	1207	=item int ev_priority (ev_TYPE *watcher)
1081		1208
1082	Set and query the priority of the watcher. The priority is a small	1209	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>	1210	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>
1084	(default: C<-2>). Pending watchers with higher priority will be invoked	1211	(default: C<-2>). Pending watchers with higher priority will be invoked
1085	before watchers with lower priority, but priority will not keep watchers	1212	before watchers with lower priority, but priority will not keep watchers
1086	from being executed (except for C<ev_idle> watchers).	1213	from being executed (except for C<ev_idle> watchers).
1087		1214
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	1215	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.	1216	you need to look at C<ev_idle> watchers, which provide this functionality.
1095		1217
1096	You I<must not> change the priority of a watcher as long as it is active or	1218	You I<must not> change the priority of a watcher as long as it is active or
1097	pending.	1219	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		1220
1102	Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is	1221	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	1222	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.	1223	or might not have been clamped to the valid range.
		1224
		1225	The default priority used by watchers when no priority has been set is
		1226	always C<0>, which is supposed to not be too high and not be too low :).
		1227
		1228	See L<WATCHER PRIORITY MODELS>, below, for a more thorough treatment of
		1229	priorities.
1105		1230
1106	=item ev_invoke (loop, ev_TYPE *watcher, int revents)	1231	=item ev_invoke (loop, ev_TYPE *watcher, int revents)
1107		1232
1108	Invoke the C<watcher> with the given C<loop> and C<revents>. Neither	1233	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	1234	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	1241	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>.	1242	watcher isn't pending it does nothing and returns C<0>.
1118		1243
1119	Sometimes it can be useful to "poll" a watcher instead of waiting for its	1244	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.	1245	callback to be invoked, which can be accomplished with this function.
		1246
		1247	=item ev_feed_event (loop, ev_TYPE *watcher, int revents)
		1248
		1249	Feeds the given event set into the event loop, as if the specified event
		1250	had happened for the specified watcher (which must be a pointer to an
		1251	initialised but not necessarily started event watcher). Obviously you must
		1252	not free the watcher as long as it has pending events.
		1253
		1254	Stopping the watcher, letting libev invoke it, or calling
		1255	C<ev_clear_pending> will clear the pending event, even if the watcher was
		1256	not started in the first place.
		1257
		1258	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related
		1259	functions that do not need a watcher.
1121		1260
1122	=back	1261	=back
1123		1262
1124		1263
1125	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	1264	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
1174	#include <stddef.h>	1313	#include <stddef.h>
1175		1314
1176	static void	1315	static void
1177	t1_cb (EV_P_ ev_timer *w, int revents)	1316	t1_cb (EV_P_ ev_timer *w, int revents)
1178	{	1317	{
1179	struct my_biggy big = (struct my_biggy *	1318	struct my_biggy big = (struct my_biggy *)
1180	(((char *)w) - offsetof (struct my_biggy, t1));	1319	(((char *)w) - offsetof (struct my_biggy, t1));
1181	}	1320	}
1182		1321
1183	static void	1322	static void
1184	t2_cb (EV_P_ ev_timer *w, int revents)	1323	t2_cb (EV_P_ ev_timer *w, int revents)
1185	{	1324	{
1186	struct my_biggy big = (struct my_biggy *	1325	struct my_biggy big = (struct my_biggy *)
1187	(((char *)w) - offsetof (struct my_biggy, t2));	1326	(((char *)w) - offsetof (struct my_biggy, t2));
1188	}	1327	}
		1328
		1329	=head2 WATCHER PRIORITY MODELS
		1330
		1331	Many event loops support I<watcher priorities>, which are usually small
		1332	integers that influence the ordering of event callback invocation
		1333	between watchers in some way, all else being equal.
		1334
		1335	In libev, Watcher priorities can be set using C<ev_set_priority>. See its
		1336	description for the more technical details such as the actual priority
		1337	range.
		1338
		1339	There are two common ways how these these priorities are being interpreted
		1340	by event loops:
		1341
		1342	In the more common lock-out model, higher priorities "lock out" invocation
		1343	of lower priority watchers, which means as long as higher priority
		1344	watchers receive events, lower priority watchers are not being invoked.
		1345
		1346	The less common only-for-ordering model uses priorities solely to order
		1347	callback invocation within a single event loop iteration: Higher priority
		1348	watchers are invoked before lower priority ones, but they all get invoked
		1349	before polling for new events.
		1350
		1351	Libev uses the second (only-for-ordering) model for all its watchers
		1352	except for idle watchers (which use the lock-out model).
		1353
		1354	The rationale behind this is that implementing the lock-out model for
		1355	watchers is not well supported by most kernel interfaces, and most event
		1356	libraries will just poll for the same events again and again as long as
		1357	their callbacks have not been executed, which is very inefficient in the
		1358	common case of one high-priority watcher locking out a mass of lower
		1359	priority ones.
		1360
		1361	Static (ordering) priorities are most useful when you have two or more
		1362	watchers handling the same resource: a typical usage example is having an
		1363	C<ev_io> watcher to receive data, and an associated C<ev_timer> to handle
		1364	timeouts. Under load, data might be received while the program handles
		1365	other jobs, but since timers normally get invoked first, the timeout
		1366	handler will be executed before checking for data. In that case, giving
		1367	the timer a lower priority than the I/O watcher ensures that I/O will be
		1368	handled first even under adverse conditions (which is usually, but not
		1369	always, what you want).
		1370
		1371	Since idle watchers use the "lock-out" model, meaning that idle watchers
		1372	will only be executed when no same or higher priority watchers have
		1373	received events, they can be used to implement the "lock-out" model when
		1374	required.
		1375
		1376	For example, to emulate how many other event libraries handle priorities,
		1377	you can associate an C<ev_idle> watcher to each such watcher, and in
		1378	the normal watcher callback, you just start the idle watcher. The real
		1379	processing is done in the idle watcher callback. This causes libev to
		1380	continously poll and process kernel event data for the watcher, but when
		1381	the lock-out case is known to be rare (which in turn is rare :), this is
		1382	workable.
		1383
		1384	Usually, however, the lock-out model implemented that way will perform
		1385	miserably under the type of load it was designed to handle. In that case,
		1386	it might be preferable to stop the real watcher before starting the
		1387	idle watcher, so the kernel will not have to process the event in case
		1388	the actual processing will be delayed for considerable time.
		1389
		1390	Here is an example of an I/O watcher that should run at a strictly lower
		1391	priority than the default, and which should only process data when no
		1392	other events are pending:
		1393
		1394	ev_idle idle; // actual processing watcher
		1395	ev_io io; // actual event watcher
		1396
		1397	static void
		1398	io_cb (EV_P_ ev_io *w, int revents)
		1399	{
		1400	// stop the I/O watcher, we received the event, but
		1401	// are not yet ready to handle it.
		1402	ev_io_stop (EV_A_ w);
		1403
		1404	// start the idle watcher to ahndle the actual event.
		1405	// it will not be executed as long as other watchers
		1406	// with the default priority are receiving events.
		1407	ev_idle_start (EV_A_ &idle);
		1408	}
		1409
		1410	static void
		1411	idle_cb (EV_P_ ev_idle *w, int revents)
		1412	{
		1413	// actual processing
		1414	read (STDIN_FILENO, ...);
		1415
		1416	// have to start the I/O watcher again, as
		1417	// we have handled the event
		1418	ev_io_start (EV_P_ &io);
		1419	}
		1420
		1421	// initialisation
		1422	ev_idle_init (&idle, idle_cb);
		1423	ev_io_init (&io, io_cb, STDIN_FILENO, EV_READ);
		1424	ev_io_start (EV_DEFAULT_ &io);
		1425
		1426	In the "real" world, it might also be beneficial to start a timer, so that
		1427	low-priority connections can not be locked out forever under load. This
		1428	enables your program to keep a lower latency for important connections
		1429	during short periods of high load, while not completely locking out less
		1430	important ones.
1189		1431
1190		1432
1191	=head1 WATCHER TYPES	1433	=head1 WATCHER TYPES
1192		1434
1193	This section describes each watcher in detail, but will not repeat	1435	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	1461	descriptors to non-blocking mode is also usually a good idea (but not
1220	required if you know what you are doing).	1462	required if you know what you are doing).
1221		1463
1222	If you cannot use non-blocking mode, then force the use of a	1464	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	1465	known-to-be-good backend (at the time of this writing, this includes only
1224	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>).	1466	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file
		1467	descriptors for which non-blocking operation makes no sense (such as
		1468	files) - libev doesn't guarentee any specific behaviour in that case.
1225		1469
1226	Another thing you have to watch out for is that it is quite easy to	1470	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	1471	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	1472	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	1473	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	1594	year, it will still time out after (roughly) one hour. "Roughly" because
1351	detecting time jumps is hard, and some inaccuracies are unavoidable (the	1595	detecting time jumps is hard, and some inaccuracies are unavoidable (the
1352	monotonic clock option helps a lot here).	1596	monotonic clock option helps a lot here).
1353		1597
1354	The callback is guaranteed to be invoked only I<after> its timeout has	1598	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	1599	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	1600	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	1601	same loop iteration then the ones with earlier time-out values are invoked
1358	C<ev_loop> recursively).	1602	before ones of the same priority with later time-out values (but this is
		1603	no longer true when a callback calls C<ev_loop> recursively).
1359		1604
1360	=head3 Be smart about timeouts	1605	=head3 Be smart about timeouts
1361		1606
1362	Many real-world problems involve some kind of timeout, usually for error	1607	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,	1608	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>	1652	C<after> argument to C<ev_timer_set>, and only ever use the C<repeat>
1408	member and C<ev_timer_again>.	1653	member and C<ev_timer_again>.
1409		1654
1410	At start:	1655	At start:
1411		1656
1412	ev_timer_init (timer, callback);	1657	ev_init (timer, callback);
1413	timer->repeat = 60.;	1658	timer->repeat = 60.;
1414	ev_timer_again (loop, timer);	1659	ev_timer_again (loop, timer);
1415		1660
1416	Each time there is some activity:	1661	Each time there is some activity:
1417		1662
…		…
1479		1724
1480	To start the timer, simply initialise the watcher and set C<last_activity>	1725	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	1726	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:	1727	callback, which will "do the right thing" and start the timer:
1483		1728
1484	ev_timer_init (timer, callback);	1729	ev_init (timer, callback);
1485	last_activity = ev_now (loop);	1730	last_activity = ev_now (loop);
1486	callback (loop, timer, EV_TIMEOUT);	1731	callback (loop, timer, EV_TIMEOUT);
1487		1732
1488	And when there is some activity, simply store the current time in	1733	And when there is some activity, simply store the current time in
1489	C<last_activity>, no libev calls at all:	1734	C<last_activity>, no libev calls at all:
…		…
1550		1795
1551	If the event loop is suspended for a long time, you can also force an	1796	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	1797	update of the time returned by C<ev_now ()> by calling C<ev_now_update
1553	()>.	1798	()>.
1554		1799
		1800	=head3 The special problems of suspended animation
		1801
		1802	When you leave the server world it is quite customary to hit machines that
		1803	can suspend/hibernate - what happens to the clocks during such a suspend?
		1804
		1805	Some quick tests made with a Linux 2.6.28 indicate that a suspend freezes
		1806	all processes, while the clocks (C<times>, C<CLOCK_MONOTONIC>) continue
		1807	to run until the system is suspended, but they will not advance while the
		1808	system is suspended. That means, on resume, it will be as if the program
		1809	was frozen for a few seconds, but the suspend time will not be counted
		1810	towards C<ev_timer> when a monotonic clock source is used. The real time
		1811	clock advanced as expected, but if it is used as sole clocksource, then a
		1812	long suspend would be detected as a time jump by libev, and timers would
		1813	be adjusted accordingly.
		1814
		1815	I would not be surprised to see different behaviour in different between
		1816	operating systems, OS versions or even different hardware.
		1817
		1818	The other form of suspend (job control, or sending a SIGSTOP) will see a
		1819	time jump in the monotonic clocks and the realtime clock. If the program
		1820	is suspended for a very long time, and monotonic clock sources are in use,
		1821	then you can expect C<ev_timer>s to expire as the full suspension time
		1822	will be counted towards the timers. When no monotonic clock source is in
		1823	use, then libev will again assume a timejump and adjust accordingly.
		1824
		1825	It might be beneficial for this latter case to call C<ev_suspend>
		1826	and C<ev_resume> in code that handles C<SIGTSTP>, to at least get
		1827	deterministic behaviour in this case (you can do nothing against
		1828	C<SIGSTOP>).
		1829
1555	=head3 Watcher-Specific Functions and Data Members	1830	=head3 Watcher-Specific Functions and Data Members
1556		1831
1557	=over 4	1832	=over 4
1558		1833
1559	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	1834	=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).	1857	If the timer is started but non-repeating, stop it (as if it timed out).
1583		1858
1584	If the timer is repeating, either start it if necessary (with the	1859	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.	1860	C<repeat> value), or reset the running timer to the C<repeat> value.
1586		1861
1587	This sounds a bit complicated, see "Be smart about timeouts", above, for a	1862	This sounds a bit complicated, see L<Be smart about timeouts>, above, for a
1588	usage example.	1863	usage example.
		1864
		1865	=item ev_tstamp ev_timer_remaining (loop, ev_timer *)
		1866
		1867	Returns the remaining time until a timer fires. If the timer is active,
		1868	then this time is relative to the current event loop time, otherwise it's
		1869	the timeout value currently configured.
		1870
		1871	That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns
		1872	C<5>. When the timer is started and one second passes, C<ev_timer_remain>
		1873	will return C<4>. When the timer expires and is restarted, it will return
		1874	roughly C<7> (likely slightly less as callback invocation takes some time,
		1875	too), and so on.
1589		1876
1590	=item ev_tstamp repeat [read-write]	1877	=item ev_tstamp repeat [read-write]
1591		1878
1592	The current C<repeat> value. Will be used each time the watcher times out	1879	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),	1880	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	2116	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	2117	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	2118	will try it's best to deliver signals synchronously, i.e. as part of the
1832	normal event processing, like any other event.	2119	normal event processing, like any other event.
1833		2120
1834	If you want signals asynchronously, just use C<sigaction> as you would	2121	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	2122	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.	2123	the signal. You can even use C<ev_async> from a signal handler to
		2124	synchronously wake up an event loop.
1837		2125
1838	You can configure as many watchers as you like per signal. Only when the	2126	You can configure as many watchers as you like for the same signal, but
		2127	only within the same loop, i.e. you can watch for C<SIGINT> in your
		2128	default loop and for C<SIGIO> in another loop, but you cannot watch for
		2129	C<SIGINT> in both the default loop and another loop at the same time. At
		2130	the moment, C<SIGCHLD> is permanently tied to the default loop.
		2131
1839	first watcher gets started will libev actually register a signal handler	2132	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	2133	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	2134	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		2135
1845	If possible and supported, libev will install its handlers with	2136	If possible and supported, libev will install its handlers with
1846	C<SA_RESTART> behaviour enabled, so system calls should not be unduly	2137	C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should
1847	interrupted. If you have a problem with system calls getting interrupted by	2138	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	2139	interrupted by signals you can block all signals in an C<ev_check> watcher
1849	them in an C<ev_prepare> watcher.	2140	and unblock them in an C<ev_prepare> watcher.
		2141
		2142	=head3 The special problem of inheritance over fork/execve/pthread_create
		2143
		2144	Both the signal mask (C<sigprocmask>) and the signal disposition
		2145	(C<sigaction>) are unspecified after starting a signal watcher (and after
		2146	stopping it again), that is, libev might or might not block the signal,
		2147	and might or might not set or restore the installed signal handler.
		2148
		2149	While this does not matter for the signal disposition (libev never
		2150	sets signals to C<SIG_IGN>, so handlers will be reset to C<SIG_DFL> on
		2151	C<execve>), this matters for the signal mask: many programs do not expect
		2152	certain signals to be blocked.
		2153
		2154	This means that before calling C<exec> (from the child) you should reset
		2155	the signal mask to whatever "default" you expect (all clear is a good
		2156	choice usually).
		2157
		2158	The simplest way to ensure that the signal mask is reset in the child is
		2159	to install a fork handler with C<pthread_atfork> that resets it. That will
		2160	catch fork calls done by libraries (such as the libc) as well.
		2161
		2162	In current versions of libev, the signal will not be blocked indefinitely
		2163	unless you use the C<signalfd> API (C<EV_SIGNALFD>). While this reduces
		2164	the window of opportunity for problems, it will not go away, as libev
		2165	I<has> to modify the signal mask, at least temporarily.
		2166
		2167	So I can't stress this enough: I<If you do not reset your signal mask when
		2168	you expect it to be empty, you have a race condition in your code>. This
		2169	is not a libev-specific thing, this is true for most event libraries.
1850		2170
1851	=head3 Watcher-Specific Functions and Data Members	2171	=head3 Watcher-Specific Functions and Data Members
1852		2172
1853	=over 4	2173	=over 4
1854		2174
…		…
1886	some child status changes (most typically when a child of yours dies or	2206	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	2207	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	2208	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.,	2209	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,	2210	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	2211	but forking and registering a watcher a few event loop iterations later or
1892	not.	2212	in the next callback invocation is not.
1893		2213
1894	Only the default event loop is capable of handling signals, and therefore	2214	Only the default event loop is capable of handling signals, and therefore
1895	you can only register child watchers in the default event loop.	2215	you can only register child watchers in the default event loop.
1896		2216
		2217	Due to some design glitches inside libev, child watchers will always be
		2218	handled at maximum priority (their priority is set to C<EV_MAXPRI> by
		2219	libev)
		2220
1897	=head3 Process Interaction	2221	=head3 Process Interaction
1898		2222
1899	Libev grabs C<SIGCHLD> as soon as the default event loop is	2223	Libev grabs C<SIGCHLD> as soon as the default event loop is
1900	initialised. This is necessary to guarantee proper behaviour even if	2224	initialised. This is necessary to guarantee proper behaviour even if the
1901	the first child watcher is started after the child exits. The occurrence	2225	first child watcher is started after the child exits. The occurrence
1902	of C<SIGCHLD> is recorded asynchronously, but child reaping is done	2226	of C<SIGCHLD> is recorded asynchronously, but child reaping is done
1903	synchronously as part of the event loop processing. Libev always reaps all	2227	synchronously as part of the event loop processing. Libev always reaps all
1904	children, even ones not watched.	2228	children, even ones not watched.
1905		2229
1906	=head3 Overriding the Built-In Processing	2230	=head3 Overriding the Built-In Processing
…		…
1916	=head3 Stopping the Child Watcher	2240	=head3 Stopping the Child Watcher
1917		2241
1918	Currently, the child watcher never gets stopped, even when the	2242	Currently, the child watcher never gets stopped, even when the
1919	child terminates, so normally one needs to stop the watcher in the	2243	child terminates, so normally one needs to stop the watcher in the
1920	callback. Future versions of libev might stop the watcher automatically	2244	callback. Future versions of libev might stop the watcher automatically
1921	when a child exit is detected.	2245	when a child exit is detected (calling C<ev_child_stop> twice is not a
		2246	problem).
1922		2247
1923	=head3 Watcher-Specific Functions and Data Members	2248	=head3 Watcher-Specific Functions and Data Members
1924		2249
1925	=over 4	2250	=over 4
1926		2251
…		…
2252	// no longer anything immediate to do.	2577	// no longer anything immediate to do.
2253	}	2578	}
2254		2579
2255	ev_idle *idle_watcher = malloc (sizeof (ev_idle));	2580	ev_idle *idle_watcher = malloc (sizeof (ev_idle));
2256	ev_idle_init (idle_watcher, idle_cb);	2581	ev_idle_init (idle_watcher, idle_cb);
2257	ev_idle_start (loop, idle_cb);	2582	ev_idle_start (loop, idle_watcher);
2258		2583
2259		2584
2260	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!	2585	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!
2261		2586
2262	Prepare and check watchers are usually (but not always) used in pairs:	2587	Prepare and check watchers are usually (but not always) used in pairs:
…		…
2355	struct pollfd fds [nfd];	2680	struct pollfd fds [nfd];
2356	// actual code will need to loop here and realloc etc.	2681	// actual code will need to loop here and realloc etc.
2357	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	2682	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
2358		2683
2359	/* the callback is illegal, but won't be called as we stop during check */	2684	/* the callback is illegal, but won't be called as we stop during check */
2360	ev_timer_init (&tw, 0, timeout * 1e-3);	2685	ev_timer_init (&tw, 0, timeout * 1e-3, 0.);
2361	ev_timer_start (loop, &tw);	2686	ev_timer_start (loop, &tw);
2362		2687
2363	// create one ev_io per pollfd	2688	// create one ev_io per pollfd
2364	for (int i = 0; i < nfd; ++i)	2689	for (int i = 0; i < nfd; ++i)
2365	{	2690	{
…		…
2595	event loop blocks next and before C<ev_check> watchers are being called,	2920	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	2921	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	2922	C<ev_default_fork> cheats and calls it in the wrong process, the fork
2598	handlers will be invoked, too, of course.	2923	handlers will be invoked, too, of course.
2599		2924
		2925	=head3 The special problem of life after fork - how is it possible?
		2926
		2927	Most uses of C<fork()> consist of forking, then some simple calls to ste
		2928	up/change the process environment, followed by a call to C<exec()>. This
		2929	sequence should be handled by libev without any problems.
		2930
		2931	This changes when the application actually wants to do event handling
		2932	in the child, or both parent in child, in effect "continuing" after the
		2933	fork.
		2934
		2935	The default mode of operation (for libev, with application help to detect
		2936	forks) is to duplicate all the state in the child, as would be expected
		2937	when I<either> the parent I<or> the child process continues.
		2938
		2939	When both processes want to continue using libev, then this is usually the
		2940	wrong result. In that case, usually one process (typically the parent) is
		2941	supposed to continue with all watchers in place as before, while the other
		2942	process typically wants to start fresh, i.e. without any active watchers.
		2943
		2944	The cleanest and most efficient way to achieve that with libev is to
		2945	simply create a new event loop, which of course will be "empty", and
		2946	use that for new watchers. This has the advantage of not touching more
		2947	memory than necessary, and thus avoiding the copy-on-write, and the
		2948	disadvantage of having to use multiple event loops (which do not support
		2949	signal watchers).
		2950
		2951	When this is not possible, or you want to use the default loop for
		2952	other reasons, then in the process that wants to start "fresh", call
		2953	C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying
		2954	the default loop will "orphan" (not stop) all registered watchers, so you
		2955	have to be careful not to execute code that modifies those watchers. Note
		2956	also that in that case, you have to re-register any signal watchers.
		2957
2600	=head3 Watcher-Specific Functions and Data Members	2958	=head3 Watcher-Specific Functions and Data Members
2601		2959
2602	=over 4	2960	=over 4
2603		2961
2604	=item ev_fork_init (ev_signal *, callback)	2962	=item ev_fork_init (ev_signal *, callback)
…		…
2633	=head3 Queueing	2991	=head3 Queueing
2634		2992
2635	C<ev_async> does not support queueing of data in any way. The reason	2993	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	2994	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	2995	multiple-writer-single-reader queue that works in all cases and doesn't
2638	need elaborate support such as pthreads.	2996	need elaborate support such as pthreads or unportable memory access
		2997	semantics.
2639		2998
2640	That means that if you want to queue data, you have to provide your own	2999	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	3000	queue. But at least I can tell you how to implement locking around your
2642	queue:	3001	queue:
2643		3002
…		…
2801	/* doh, nothing entered */;	3160	/* doh, nothing entered */;
2802	}	3161	}
2803		3162
2804	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	3163	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
2805		3164
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)	3165	=item ev_feed_fd_event (loop, int fd, int revents)
2813		3166
2814	Feed an event on the given fd, as if a file descriptor backend detected	3167	Feed an event on the given fd, as if a file descriptor backend detected
2815	the given events it.	3168	the given events it.
2816		3169
2817	=item ev_feed_signal_event (struct ev_loop *loop, int signum)	3170	=item ev_feed_signal_event (loop, int signum)
2818		3171
2819	Feed an event as if the given signal occurred (C<loop> must be the default	3172	Feed an event as if the given signal occurred (C<loop> must be the default
2820	loop!).	3173	loop!).
2821		3174
2822	=back	3175	=back
…		…
2902		3255
2903	=over 4	3256	=over 4
2904		3257
2905	=item ev::TYPE::TYPE ()	3258	=item ev::TYPE::TYPE ()
2906		3259
2907	=item ev::TYPE::TYPE (struct ev_loop *)	3260	=item ev::TYPE::TYPE (loop)
2908		3261
2909	=item ev::TYPE::~TYPE	3262	=item ev::TYPE::~TYPE
2910		3263
2911	The constructor (optionally) takes an event loop to associate the watcher	3264	The constructor (optionally) takes an event loop to associate the watcher
2912	with. If it is omitted, it will use C<EV_DEFAULT>.	3265	with. If it is omitted, it will use C<EV_DEFAULT>.
…		…
2989	Example: Use a plain function as callback.	3342	Example: Use a plain function as callback.
2990		3343
2991	static void io_cb (ev::io &w, int revents) { }	3344	static void io_cb (ev::io &w, int revents) { }
2992	iow.set <io_cb> ();	3345	iow.set <io_cb> ();
2993		3346
2994	=item w->set (struct ev_loop *)	3347	=item w->set (loop)
2995		3348
2996	Associates a different C<struct ev_loop> with this watcher. You can only	3349	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).	3350	do this when the watcher is inactive (and not pending either).
2998		3351
2999	=item w->set ([arguments])	3352	=item w->set ([arguments])
…		…
3096	=item Ocaml	3449	=item Ocaml
3097		3450
3098	Erkki Seppala has written Ocaml bindings for libev, to be found at	3451	Erkki Seppala has written Ocaml bindings for libev, to be found at
3099	L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>.	3452	L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>.
3100		3453
		3454	=item Lua
		3455
		3456	Brian Maher has written a partial interface to libev
		3457	for lua (only C<ev_io> and C<ev_timer>), to be found at
		3458	L<http://github.com/brimworks/lua-ev>.
		3459
3101	=back	3460	=back
3102		3461
3103		3462
3104	=head1 MACRO MAGIC	3463	=head1 MACRO MAGIC
3105		3464
…		…
3271	keeps libev from including F<config.h>, and it also defines dummy	3630	keeps libev from including F<config.h>, and it also defines dummy
3272	implementations for some libevent functions (such as logging, which is not	3631	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	3632	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.	3633	F<event.h> that are not directly supported by the libev core alone.
3275		3634
3276	In stanbdalone mode, libev will still try to automatically deduce the	3635	In standalone mode, libev will still try to automatically deduce the
3277	configuration, but has to be more conservative.	3636	configuration, but has to be more conservative.
3278		3637
3279	=item EV_USE_MONOTONIC	3638	=item EV_USE_MONOTONIC
3280		3639
3281	If defined to be C<1>, libev will try to detect the availability of the	3640	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	3705	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,	3706	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	3707	it is assumed that all these functions actually work on fds, even
3349	on win32. Should not be defined on non-win32 platforms.	3708	on win32. Should not be defined on non-win32 platforms.
3350		3709
3351	=item EV_FD_TO_WIN32_HANDLE	3710	=item EV_FD_TO_WIN32_HANDLE(fd)
3352		3711
3353	If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map	3712	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	3713	file descriptors to socket handles. When not defining this symbol (the
3355	default), then libev will call C<_get_osfhandle>, which is usually	3714	default), then libev will call C<_get_osfhandle>, which is usually
3356	correct. In some cases, programs use their own file descriptor management,	3715	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.	3716	in which case they can provide this function to map fds to socket handles.
		3717
		3718	=item EV_WIN32_HANDLE_TO_FD(handle)
		3719
		3720	If C<EV_SELECT_IS_WINSOCKET> then libev maps handles to file descriptors
		3721	using the standard C<_open_osfhandle> function. For programs implementing
		3722	their own fd to handle mapping, overwriting this function makes it easier
		3723	to do so. This can be done by defining this macro to an appropriate value.
		3724
		3725	=item EV_WIN32_CLOSE_FD(fd)
		3726
		3727	If programs implement their own fd to handle mapping on win32, then this
		3728	macro can be used to override the C<close> function, useful to unregister
		3729	file descriptors again. Note that the replacement function has to close
		3730	the underlying OS handle.
3358		3731
3359	=item EV_USE_POLL	3732	=item EV_USE_POLL
3360		3733
3361	If defined to be C<1>, libev will compile in support for the C<poll>(2)	3734	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	3735	backend. Otherwise it will be enabled on non-win32 platforms. It
…		…
3494	defined to be C<0>, then they are not.	3867	defined to be C<0>, then they are not.
3495		3868
3496	=item EV_MINIMAL	3869	=item EV_MINIMAL
3497		3870
3498	If you need to shave off some kilobytes of code at the expense of some	3871	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	3872	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	3873	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.	3874	on amd64. It also selects a much smaller 2-heap for timer management over
		3875	the default 4-heap.
		3876
		3877	You can save even more by disabling watcher types you do not need
		3878	and setting C<EV_MAXPRI> == C<EV_MINPRI>. Also, disabling C<assert>
		3879	(C<-DNDEBUG>) will usually reduce code size a lot.
		3880
		3881	Defining C<EV_MINIMAL> to C<2> will additionally reduce the core API to
		3882	provide a bare-bones event library. See C<ev.h> for details on what parts
		3883	of the API are still available, and do not complain if this subset changes
		3884	over time.
		3885
		3886	=item EV_NSIG
		3887
		3888	The highest supported signal number, +1 (or, the number of
		3889	signals): Normally, libev tries to deduce the maximum number of signals
		3890	automatically, but sometimes this fails, in which case it can be
		3891	specified. Also, using a lower number than detected (C<32> should be
		3892	good for about any system in existance) can save some memory, as libev
		3893	statically allocates some 12-24 bytes per signal number.
3502		3894
3503	=item EV_PID_HASHSIZE	3895	=item EV_PID_HASHSIZE
3504		3896
3505	C<ev_child> watchers use a small hash table to distribute workload by	3897	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	3898	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	4084	default loop and triggering an C<ev_async> watcher from the default loop
3693	watcher callback into the event loop interested in the signal.	4085	watcher callback into the event loop interested in the signal.
3694		4086
3695	=back	4087	=back
3696		4088
		4089	=head4 THREAD LOCKING EXAMPLE
		4090
		4091	Here is a fictitious example of how to run an event loop in a different
		4092	thread than where callbacks are being invoked and watchers are
		4093	created/added/removed.
		4094
		4095	For a real-world example, see the C<EV::Loop::Async> perl module,
		4096	which uses exactly this technique (which is suited for many high-level
		4097	languages).
		4098
		4099	The example uses a pthread mutex to protect the loop data, a condition
		4100	variable to wait for callback invocations, an async watcher to notify the
		4101	event loop thread and an unspecified mechanism to wake up the main thread.
		4102
		4103	First, you need to associate some data with the event loop:
		4104
		4105	typedef struct {
		4106	mutex_t lock; /* global loop lock */
		4107	ev_async async_w;
		4108	thread_t tid;
		4109	cond_t invoke_cv;
		4110	} userdata;
		4111
		4112	void prepare_loop (EV_P)
		4113	{
		4114	// for simplicity, we use a static userdata struct.
		4115	static userdata u;
		4116
		4117	ev_async_init (&u->async_w, async_cb);
		4118	ev_async_start (EV_A_ &u->async_w);
		4119
		4120	pthread_mutex_init (&u->lock, 0);
		4121	pthread_cond_init (&u->invoke_cv, 0);
		4122
		4123	// now associate this with the loop
		4124	ev_set_userdata (EV_A_ u);
		4125	ev_set_invoke_pending_cb (EV_A_ l_invoke);
		4126	ev_set_loop_release_cb (EV_A_ l_release, l_acquire);
		4127
		4128	// then create the thread running ev_loop
		4129	pthread_create (&u->tid, 0, l_run, EV_A);
		4130	}
		4131
		4132	The callback for the C<ev_async> watcher does nothing: the watcher is used
		4133	solely to wake up the event loop so it takes notice of any new watchers
		4134	that might have been added:
		4135
		4136	static void
		4137	async_cb (EV_P_ ev_async *w, int revents)
		4138	{
		4139	// just used for the side effects
		4140	}
		4141
		4142	The C<l_release> and C<l_acquire> callbacks simply unlock/lock the mutex
		4143	protecting the loop data, respectively.
		4144
		4145	static void
		4146	l_release (EV_P)
		4147	{
		4148	userdata *u = ev_userdata (EV_A);
		4149	pthread_mutex_unlock (&u->lock);
		4150	}
		4151
		4152	static void
		4153	l_acquire (EV_P)
		4154	{
		4155	userdata *u = ev_userdata (EV_A);
		4156	pthread_mutex_lock (&u->lock);
		4157	}
		4158
		4159	The event loop thread first acquires the mutex, and then jumps straight
		4160	into C<ev_loop>:
		4161
		4162	void *
		4163	l_run (void *thr_arg)
		4164	{
		4165	struct ev_loop loop = (struct ev_loop )thr_arg;
		4166
		4167	l_acquire (EV_A);
		4168	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
		4169	ev_loop (EV_A_ 0);
		4170	l_release (EV_A);
		4171
		4172	return 0;
		4173	}
		4174
		4175	Instead of invoking all pending watchers, the C<l_invoke> callback will
		4176	signal the main thread via some unspecified mechanism (signals? pipe
		4177	writes? C<Async::Interrupt>?) and then waits until all pending watchers
		4178	have been called (in a while loop because a) spurious wakeups are possible
		4179	and b) skipping inter-thread-communication when there are no pending
		4180	watchers is very beneficial):
		4181
		4182	static void
		4183	l_invoke (EV_P)
		4184	{
		4185	userdata *u = ev_userdata (EV_A);
		4186
		4187	while (ev_pending_count (EV_A))
		4188	{
		4189	wake_up_other_thread_in_some_magic_or_not_so_magic_way ();
		4190	pthread_cond_wait (&u->invoke_cv, &u->lock);
		4191	}
		4192	}
		4193
		4194	Now, whenever the main thread gets told to invoke pending watchers, it
		4195	will grab the lock, call C<ev_invoke_pending> and then signal the loop
		4196	thread to continue:
		4197
		4198	static void
		4199	real_invoke_pending (EV_P)
		4200	{
		4201	userdata *u = ev_userdata (EV_A);
		4202
		4203	pthread_mutex_lock (&u->lock);
		4204	ev_invoke_pending (EV_A);
		4205	pthread_cond_signal (&u->invoke_cv);
		4206	pthread_mutex_unlock (&u->lock);
		4207	}
		4208
		4209	Whenever you want to start/stop a watcher or do other modifications to an
		4210	event loop, you will now have to lock:
		4211
		4212	ev_timer timeout_watcher;
		4213	userdata *u = ev_userdata (EV_A);
		4214
		4215	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
		4216
		4217	pthread_mutex_lock (&u->lock);
		4218	ev_timer_start (EV_A_ &timeout_watcher);
		4219	ev_async_send (EV_A_ &u->async_w);
		4220	pthread_mutex_unlock (&u->lock);
		4221
		4222	Note that sending the C<ev_async> watcher is required because otherwise
		4223	an event loop currently blocking in the kernel will have no knowledge
		4224	about the newly added timer. By waking up the loop it will pick up any new
		4225	watchers in the next event loop iteration.
		4226
3697	=head3 COROUTINES	4227	=head3 COROUTINES
3698		4228
3699	Libev is very accommodating to coroutines ("cooperative threads"):	4229	Libev is very accommodating to coroutines ("cooperative threads"):
3700	libev fully supports nesting calls to its functions from different	4230	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	4231	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	4232	different coroutines, and switch freely between both coroutines running
3703	loop, as long as you don't confuse yourself). The only exception is that	4233	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.	4234	that you must not do this from C<ev_periodic> reschedule callbacks.
3705		4235
3706	Care has been taken to ensure that libev does not keep local state inside	4236	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	4237	C<ev_loop>, and other calls do not usually allow for coroutine switches as
3708	they do not call any callbacks.	4238	they do not call any callbacks.
3709		4239
…		…
3786	way (note also that glib is the slowest event library known to man).	4316	way (note also that glib is the slowest event library known to man).
3787		4317
3788	There is no supported compilation method available on windows except	4318	There is no supported compilation method available on windows except
3789	embedding it into other applications.	4319	embedding it into other applications.
3790		4320
		4321	Sensible signal handling is officially unsupported by Microsoft - libev
		4322	tries its best, but under most conditions, signals will simply not work.
		4323
3791	Not a libev limitation but worth mentioning: windows apparently doesn't	4324	Not a libev limitation but worth mentioning: windows apparently doesn't
3792	accept large writes: instead of resulting in a partial write, windows will	4325	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,	4326	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	4327	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	4328	megabyte seems safe, but this apparently depends on the amount of memory
…		…
3799	the abysmal performance of winsockets, using a large number of sockets	4332	the abysmal performance of winsockets, using a large number of sockets
3800	is not recommended (and not reasonable). If your program needs to use	4333	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	4334	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	4335	different implementation for windows, as libev offers the POSIX readiness
3803	notification model, which cannot be implemented efficiently on windows	4336	notification model, which cannot be implemented efficiently on windows
3804	(Microsoft monopoly games).	4337	(due to Microsoft monopoly games).
3805		4338
3806	A typical way to use libev under windows is to embed it (see the embedding	4339	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	4340	section for details) and use the following F<evwrap.h> header file instead
3808	of F<ev.h>:	4341	of F<ev.h>:
3809		4342
…		…
3845		4378
3846	Early versions of winsocket's select only supported waiting for a maximum	4379	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	4380	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	4381	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	4382	recommends spawning a chain of threads and wait for 63 handles and the
3850	previous thread in each. Great).	4383	previous thread in each. Sounds great!).
3851		4384
3852	Newer versions support more handles, but you need to define C<FD_SETSIZE>	4385	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	4386	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	4387	call (which might be in libev or elsewhere, for example, perl and many
3855	select emulation on windows).	4388	other interpreters do their own select emulation on windows).
3856		4389
3857	Another limit is the number of file descriptors in the Microsoft runtime	4390	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	4391	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	4392	fetish or something like this inside Microsoft). You can increase this
3860	C<_setmaxstdio>, which can increase this limit to C<2048> (another	4393	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	4394	(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	4395	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	4396	(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	4397	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.	4398	the cost of calling select (O(n²)) will likely make this unworkable.
3868		4399
3869	=back	4400	=back
3870		4401
3871	=head2 PORTABILITY REQUIREMENTS	4402	=head2 PORTABILITY REQUIREMENTS
3872		4403
…		…
3915	=item C<double> must hold a time value in seconds with enough accuracy	4446	=item C<double> must hold a time value in seconds with enough accuracy
3916		4447
3917	The type C<double> is used to represent timestamps. It is required to	4448	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	4449	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	4450	enough for at least into the year 4000. This requirement is fulfilled by
3920	implementations implementing IEEE 754 (basically all existing ones).	4451	implementations implementing IEEE 754, which is basically all existing
		4452	ones. With IEEE 754 doubles, you get microsecond accuracy until at least
		4453	2200.
3921		4454
3922	=back	4455	=back
3923		4456
3924	If you know of other additional requirements drop me a note.	4457	If you know of other additional requirements drop me a note.
3925		4458
…		…
3993	involves iterating over all running async watchers or all signal numbers.	4526	involves iterating over all running async watchers or all signal numbers.
3994		4527
3995	=back	4528	=back
3996		4529
3997		4530
		4531	=head1 GLOSSARY
		4532
		4533	=over 4
		4534
		4535	=item active
		4536
		4537	A watcher is active as long as it has been started (has been attached to
		4538	an event loop) but not yet stopped (disassociated from the event loop).
		4539
		4540	=item application
		4541
		4542	In this document, an application is whatever is using libev.
		4543
		4544	=item callback
		4545
		4546	The address of a function that is called when some event has been
		4547	detected. Callbacks are being passed the event loop, the watcher that
		4548	received the event, and the actual event bitset.
		4549
		4550	=item callback invocation
		4551
		4552	The act of calling the callback associated with a watcher.
		4553
		4554	=item event
		4555
		4556	A change of state of some external event, such as data now being available
		4557	for reading on a file descriptor, time having passed or simply not having
		4558	any other events happening anymore.
		4559
		4560	In libev, events are represented as single bits (such as C<EV_READ> or
		4561	C<EV_TIMEOUT>).
		4562
		4563	=item event library
		4564
		4565	A software package implementing an event model and loop.
		4566
		4567	=item event loop
		4568
		4569	An entity that handles and processes external events and converts them
		4570	into callback invocations.
		4571
		4572	=item event model
		4573
		4574	The model used to describe how an event loop handles and processes
		4575	watchers and events.
		4576
		4577	=item pending
		4578
		4579	A watcher is pending as soon as the corresponding event has been detected,
		4580	and stops being pending as soon as the watcher will be invoked or its
		4581	pending status is explicitly cleared by the application.
		4582
		4583	A watcher can be pending, but not active. Stopping a watcher also clears
		4584	its pending status.
		4585
		4586	=item real time
		4587
		4588	The physical time that is observed. It is apparently strictly monotonic :)
		4589
		4590	=item wall-clock time
		4591
		4592	The time and date as shown on clocks. Unlike real time, it can actually
		4593	be wrong and jump forwards and backwards, e.g. when the you adjust your
		4594	clock.
		4595
		4596	=item watcher
		4597
		4598	A data structure that describes interest in certain events. Watchers need
		4599	to be started (attached to an event loop) before they can receive events.
		4600
		4601	=item watcher invocation
		4602
		4603	The act of calling the callback associated with a watcher.
		4604
		4605	=back
		4606
3998	=head1 AUTHOR	4607	=head1 AUTHOR
3999		4608
4000	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson.	4609	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson.
4001		4610

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing libev/ev.pod (file contents): Revision 1.231 by root, Wed Apr 15 19:35:53 2009 UTC vs. Revision 1.278 by root, Thu Dec 31 06:59:47 2009 UTC

Diff Legend

Comparing libev/ev.pod (file contents):
Revision 1.231 by root, Wed Apr 15 19:35:53 2009 UTC vs.
Revision 1.278 by root, Thu Dec 31 06:59:47 2009 UTC