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…		…
8		8
9	=head2 EXAMPLE PROGRAM	9	=head2 EXAMPLE PROGRAM
10		10
11	// a single header file is required	11	// a single header file is required
12	#include <ev.h>	12	#include <ev.h>
		13
		14	#include <stdio.h> // for puts
13		15
14	// every watcher type has its own typedef'd struct	16	// every watcher type has its own typedef'd struct
15	// with the name ev_TYPE	17	// with the name ev_TYPE
16	ev_io stdin_watcher;	18	ev_io stdin_watcher;
17	ev_timer timeout_watcher;	19	ev_timer timeout_watcher;
…		…
24	puts ("stdin ready");	26	puts ("stdin ready");
25	// for one-shot events, one must manually stop the watcher	27	// for one-shot events, one must manually stop the watcher
26	// with its corresponding stop function.	28	// with its corresponding stop function.
27	ev_io_stop (EV_A_ w);	29	ev_io_stop (EV_A_ w);
28		30
29	// this causes all nested ev_loop's to stop iterating	31	// this causes all nested ev_run's to stop iterating
30	ev_unloop (EV_A_ EVUNLOOP_ALL);	32	ev_break (EV_A_ EVBREAK_ALL);
31	}	33	}
32		34
33	// another callback, this time for a time-out	35	// another callback, this time for a time-out
34	static void	36	static void
35	timeout_cb (EV_P_ ev_timer *w, int revents)	37	timeout_cb (EV_P_ ev_timer *w, int revents)
36	{	38	{
37	puts ("timeout");	39	puts ("timeout");
38	// this causes the innermost ev_loop to stop iterating	40	// this causes the innermost ev_run to stop iterating
39	ev_unloop (EV_A_ EVUNLOOP_ONE);	41	ev_break (EV_A_ EVBREAK_ONE);
40	}	42	}
41		43
42	int	44	int
43	main (void)	45	main (void)
44	{	46	{
45	// use the default event loop unless you have special needs	47	// use the default event loop unless you have special needs
46	ev_loop *loop = ev_default_loop (0);	48	struct ev_loop *loop = ev_default_loop (0);
47		49
48	// initialise an io watcher, then start it	50	// initialise an io watcher, then start it
49	// this one will watch for stdin to become readable	51	// this one will watch for stdin to become readable
50	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);	52	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);
51	ev_io_start (loop, &stdin_watcher);	53	ev_io_start (loop, &stdin_watcher);
…		…
54	// simple non-repeating 5.5 second timeout	56	// simple non-repeating 5.5 second timeout
55	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);	57	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
56	ev_timer_start (loop, &timeout_watcher);	58	ev_timer_start (loop, &timeout_watcher);
57		59
58	// now wait for events to arrive	60	// now wait for events to arrive
59	ev_loop (loop, 0);	61	ev_run (loop, 0);
60		62
61	// unloop was called, so exit	63	// unloop was called, so exit
62	return 0;	64	return 0;
63	}	65	}
64		66
65	=head1 DESCRIPTION	67	=head1 ABOUT THIS DOCUMENT
		68
		69	This document documents the libev software package.
66		70
67	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
68	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
69	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	Familiarity with event based programming techniques in general is assumed
		81	throughout this document.
		82
		83	=head1 ABOUT LIBEV
70		84
71	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
72	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
73	these event sources and provide your program with events.	87	these event sources and provide your program with events.
74		88
…		…
84	=head2 FEATURES	98	=head2 FEATURES
85		99
86	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
87	BSD-specific C<kqueue> and the Solaris-specific event port mechanisms	101	BSD-specific C<kqueue> and the Solaris-specific event port mechanisms
88	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
89	(for C<ev_stat>), relative timers (C<ev_timer>), absolute timers	103	(for C<ev_stat>), Linux eventfd/signalfd (for faster and cleaner
90	with customised rescheduling (C<ev_periodic>), synchronous signals	104	inter-thread wakeup (C<ev_async>)/signal handling (C<ev_signal>)) relative
91	(C<ev_signal>), process status change events (C<ev_child>), and event	105	timers (C<ev_timer>), absolute timers with customised rescheduling
92	watchers dealing with the event loop mechanism itself (C<ev_idle>,	106	(C<ev_periodic>), synchronous signals (C<ev_signal>), process status
93	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
94	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
95	(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>).
96		111
97	It also is quite fast (see this	112	It also is quite fast (see this
98	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
99	for example).	114	for example).
100		115
…		…
103	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)
104	configuration will be described, which supports multiple event loops. For	119	configuration will be described, which supports multiple event loops. For
105	more info about various configuration options please have a look at	120	more info about various configuration options please have a look at
106	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
107	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
108	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
109	this argument.	124	this argument.
110		125
111	=head2 TIME REPRESENTATION	126	=head2 TIME REPRESENTATION
112		127
113	Libev represents time as a single floating point number, representing the	128	Libev represents time as a single floating point number, representing
114	(fractional) number of seconds since the (POSIX) epoch (somewhere near	129	the (fractional) number of seconds since the (POSIX) epoch (in practice
115	the beginning of 1970, details are complicated, don't ask). This type is	130	somewhere near the beginning of 1970, details are complicated, don't
116	called C<ev_tstamp>, which is what you should use too. It usually aliases	131	ask). This type is called C<ev_tstamp>, which is what you should use
117	to the C<double> type in C, and when you need to do any calculations on	132	too. It usually aliases to the C<double> type in C. When you need to do
118	it, you should treat it as some floating point value. Unlike the name	133	any calculations on it, you should treat it as some floating point value.
		134
119	component C<stamp> might indicate, it is also used for time differences	135	Unlike the name component C<stamp> might indicate, it is also used for
120	throughout libev.	136	time differences (e.g. delays) throughout libev.
121		137
122	=head1 ERROR HANDLING	138	=head1 ERROR HANDLING
123		139
124	Libev knows three classes of errors: operating system errors, usage errors	140	Libev knows three classes of errors: operating system errors, usage errors
125	and internal errors (bugs).	141	and internal errors (bugs).
…		…
149		165
150	=item ev_tstamp ev_time ()	166	=item ev_tstamp ev_time ()
151		167
152	Returns the current time as libev would use it. Please note that the	168	Returns the current time as libev would use it. Please note that the
153	C<ev_now> function is usually faster and also often returns the timestamp	169	C<ev_now> function is usually faster and also often returns the timestamp
154	you actually want to know.	170	you actually want to know. Also interetsing is the combination of
		171	C<ev_update_now> and C<ev_now>.
155		172
156	=item ev_sleep (ev_tstamp interval)	173	=item ev_sleep (ev_tstamp interval)
157		174
158	Sleep for the given interval: The current thread will be blocked until	175	Sleep for the given interval: The current thread will be blocked until
159	either it is interrupted or the given time interval has passed. Basically	176	either it is interrupted or the given time interval has passed. Basically
…		…
176	as this indicates an incompatible change. Minor versions are usually	193	as this indicates an incompatible change. Minor versions are usually
177	compatible to older versions, so a larger minor version alone is usually	194	compatible to older versions, so a larger minor version alone is usually
178	not a problem.	195	not a problem.
179		196
180	Example: Make sure we haven't accidentally been linked against the wrong	197	Example: Make sure we haven't accidentally been linked against the wrong
181	version.	198	version (note, however, that this will not detect ABI mismatches :).
182		199
183	assert (("libev version mismatch",	200	assert (("libev version mismatch",
184	ev_version_major () == EV_VERSION_MAJOR	201	ev_version_major () == EV_VERSION_MAJOR
185	&& ev_version_minor () >= EV_VERSION_MINOR));	202	&& ev_version_minor () >= EV_VERSION_MINOR));
186		203
…		…
197	assert (("sorry, no epoll, no sex",	214	assert (("sorry, no epoll, no sex",
198	ev_supported_backends () & EVBACKEND_EPOLL));	215	ev_supported_backends () & EVBACKEND_EPOLL));
199		216
200	=item unsigned int ev_recommended_backends ()	217	=item unsigned int ev_recommended_backends ()
201		218
202	Return the set of all backends compiled into this binary of libev and also	219	Return the set of all backends compiled into this binary of libev and
203	recommended for this platform. This set is often smaller than the one	220	also recommended for this platform, meaning it will work for most file
		221	descriptor types. This set is often smaller than the one returned by
204	returned by C<ev_supported_backends>, as for example kqueue is broken on	222	C<ev_supported_backends>, as for example kqueue is broken on most BSDs
205	most BSDs and will not be auto-detected unless you explicitly request it	223	and will not be auto-detected unless you explicitly request it (assuming
206	(assuming you know what you are doing). This is the set of backends that	224	you know what you are doing). This is the set of backends that libev will
207	libev will probe for if you specify no backends explicitly.	225	probe for if you specify no backends explicitly.
208		226
209	=item unsigned int ev_embeddable_backends ()	227	=item unsigned int ev_embeddable_backends ()
210		228
211	Returns the set of backends that are embeddable in other event loops. This	229	Returns the set of backends that are embeddable in other event loops. This
212	is the theoretical, all-platform, value. To find which backends	230	is the theoretical, all-platform, value. To find which backends
…		…
276		294
277	=back	295	=back
278		296
279	=head1 FUNCTIONS CONTROLLING THE EVENT LOOP	297	=head1 FUNCTIONS CONTROLLING THE EVENT LOOP
280		298
281	An event loop is described by a C<struct ev_loop *> (the C<struct>	299	An event loop is described by a C<struct ev_loop *> (the C<struct> is
282	is I<not> optional in this case, as there is also an C<ev_loop>	300	I<not> optional in this case unless libev 3 compatibility is disabled, as
283	I<function>).	301	libev 3 had an C<ev_loop> function colliding with the struct name).
284		302
285	The library knows two types of such loops, the I<default> loop, which	303	The library knows two types of such loops, the I<default> loop, which
286	supports signals and child events, and dynamically created loops which do	304	supports signals and child events, and dynamically created event loops
287	not.	305	which do not.
288		306
289	=over 4	307	=over 4
290		308
291	=item struct ev_loop *ev_default_loop (unsigned int flags)	309	=item struct ev_loop *ev_default_loop (unsigned int flags)
292		310
…		…
298	If you don't know what event loop to use, use the one returned from this	316	If you don't know what event loop to use, use the one returned from this
299	function.	317	function.
300		318
301	Note that this function is I<not> thread-safe, so if you want to use it	319	Note that this function is I<not> thread-safe, so if you want to use it
302	from multiple threads, you have to lock (note also that this is unlikely,	320	from multiple threads, you have to lock (note also that this is unlikely,
303	as loops cannot bes hared easily between threads anyway).	321	as loops cannot be shared easily between threads anyway).
304		322
305	The default loop is the only loop that can handle C<ev_signal> and	323	The default loop is the only loop that can handle C<ev_signal> and
306	C<ev_child> watchers, and to do this, it always registers a handler	324	C<ev_child> watchers, and to do this, it always registers a handler
307	for C<SIGCHLD>. If this is a problem for your application you can either	325	for C<SIGCHLD>. If this is a problem for your application you can either
308	create a dynamic loop with C<ev_loop_new> that doesn't do that, or you	326	create a dynamic loop with C<ev_loop_new> that doesn't do that, or you
…		…
330	useful to try out specific backends to test their performance, or to work	348	useful to try out specific backends to test their performance, or to work
331	around bugs.	349	around bugs.
332		350
333	=item C<EVFLAG_FORKCHECK>	351	=item C<EVFLAG_FORKCHECK>
334		352
335	Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after	353	Instead of calling C<ev_loop_fork> manually after a fork, you can also
336	a fork, you can also make libev check for a fork in each iteration by	354	make libev check for a fork in each iteration by enabling this flag.
337	enabling this flag.
338		355
339	This works by calling C<getpid ()> on every iteration of the loop,	356	This works by calling C<getpid ()> on every iteration of the loop,
340	and thus this might slow down your event loop if you do a lot of loop	357	and thus this might slow down your event loop if you do a lot of loop
341	iterations and little real work, but is usually not noticeable (on my	358	iterations and little real work, but is usually not noticeable (on my
342	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence	359	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence
…		…
348	flag.	365	flag.
349		366
350	This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS>	367	This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS>
351	environment variable.	368	environment variable.
352		369
		370	=item C<EVFLAG_NOINOTIFY>
		371
		372	When this flag is specified, then libev will not attempt to use the
		373	I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and
		374	testing, this flag can be useful to conserve inotify file descriptors, as
		375	otherwise each loop using C<ev_stat> watchers consumes one inotify handle.
		376
		377	=item C<EVFLAG_SIGNALFD>
		378
		379	When this flag is specified, then libev will attempt to use the
		380	I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This API
		381	delivers signals synchronously, which makes it both faster and might make
		382	it possible to get the queued signal data. It can also simplify signal
		383	handling with threads, as long as you properly block signals in your
		384	threads that are not interested in handling them.
		385
		386	Signalfd will not be used by default as this changes your signal mask, and
		387	there are a lot of shoddy libraries and programs (glib's threadpool for
		388	example) that can't properly initialise their signal masks.
		389
353	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	390	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
354		391
355	This is your standard select(2) backend. Not I<completely> standard, as	392	This is your standard select(2) backend. Not I<completely> standard, as
356	libev tries to roll its own fd_set with no limits on the number of fds,	393	libev tries to roll its own fd_set with no limits on the number of fds,
357	but if that fails, expect a fairly low limit on the number of fds when	394	but if that fails, expect a fairly low limit on the number of fds when
…		…
381	This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and	418	This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and
382	C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>.	419	C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>.
383		420
384	=item C<EVBACKEND_EPOLL> (value 4, Linux)	421	=item C<EVBACKEND_EPOLL> (value 4, Linux)
385		422
		423	Use the linux-specific epoll(7) interface (for both pre- and post-2.6.9
		424	kernels).
		425
386	For few fds, this backend is a bit little slower than poll and select,	426	For few fds, this backend is a bit little slower than poll and select,
387	but it scales phenomenally better. While poll and select usually scale	427	but it scales phenomenally better. While poll and select usually scale
388	like O(total_fds) where n is the total number of fds (or the highest fd),	428	like O(total_fds) where n is the total number of fds (or the highest fd),
389	epoll scales either O(1) or O(active_fds). The epoll design has a number	429	epoll scales either O(1) or O(active_fds).
390	of shortcomings, such as silently dropping events in some hard-to-detect	430
391	cases and requiring a system call per fd change, no fork support and bad	431	The epoll mechanism deserves honorable mention as the most misdesigned
392	support for dup.	432	of the more advanced event mechanisms: mere annoyances include silently
		433	dropping file descriptors, requiring a system call per change per file
		434	descriptor (and unnecessary guessing of parameters), problems with dup and
		435	so on. The biggest issue is fork races, however - if a program forks then
		436	I<both> parent and child process have to recreate the epoll set, which can
		437	take considerable time (one syscall per file descriptor) and is of course
		438	hard to detect.
		439
		440	Epoll is also notoriously buggy - embedding epoll fds I<should> work, but
		441	of course I<doesn't>, and epoll just loves to report events for totally
		442	I<different> file descriptors (even already closed ones, so one cannot
		443	even remove them from the set) than registered in the set (especially
		444	on SMP systems). Libev tries to counter these spurious notifications by
		445	employing an additional generation counter and comparing that against the
		446	events to filter out spurious ones, recreating the set when required. Last
		447	not least, it also refuses to work with some file descriptors which work
		448	perfectly fine with C<select> (files, many character devices...).
393		449
394	While stopping, setting and starting an I/O watcher in the same iteration	450	While stopping, setting and starting an I/O watcher in the same iteration
395	will result in some caching, there is still a system call per such incident	451	will result in some caching, there is still a system call per such
396	(because the fd could point to a different file description now), so its	452	incident (because the same I<file descriptor> could point to a different
397	best to avoid that. Also, C<dup ()>'ed file descriptors might not work	453	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed
398	very well if you register events for both fds.	454	file descriptors might not work very well if you register events for both
399		455	file descriptors.
400	Please note that epoll sometimes generates spurious notifications, so you
401	need to use non-blocking I/O or other means to avoid blocking when no data
402	(or space) is available.
403		456
404	Best performance from this backend is achieved by not unregistering all	457	Best performance from this backend is achieved by not unregistering all
405	watchers for a file descriptor until it has been closed, if possible,	458	watchers for a file descriptor until it has been closed, if possible,
406	i.e. keep at least one watcher active per fd at all times. Stopping and	459	i.e. keep at least one watcher active per fd at all times. Stopping and
407	starting a watcher (without re-setting it) also usually doesn't cause	460	starting a watcher (without re-setting it) also usually doesn't cause
408	extra overhead.	461	extra overhead. A fork can both result in spurious notifications as well
		462	as in libev having to destroy and recreate the epoll object, which can
		463	take considerable time and thus should be avoided.
		464
		465	All this means that, in practice, C<EVBACKEND_SELECT> can be as fast or
		466	faster than epoll for maybe up to a hundred file descriptors, depending on
		467	the usage. So sad.
409		468
410	While nominally embeddable in other event loops, this feature is broken in	469	While nominally embeddable in other event loops, this feature is broken in
411	all kernel versions tested so far.	470	all kernel versions tested so far.
412		471
413	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as	472	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as
414	C<EVBACKEND_POLL>.	473	C<EVBACKEND_POLL>.
415		474
416	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)	475	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)
417		476
418	Kqueue deserves special mention, as at the time of this writing, it was	477	Kqueue deserves special mention, as at the time of this writing, it
419	broken on all BSDs except NetBSD (usually it doesn't work reliably with	478	was broken on all BSDs except NetBSD (usually it doesn't work reliably
420	anything but sockets and pipes, except on Darwin, where of course it's	479	with anything but sockets and pipes, except on Darwin, where of course
421	completely useless). For this reason it's not being "auto-detected" unless	480	it's completely useless). Unlike epoll, however, whose brokenness
422	you explicitly specify it in the flags (i.e. using C<EVBACKEND_KQUEUE>) or	481	is by design, these kqueue bugs can (and eventually will) be fixed
423	libev was compiled on a known-to-be-good (-enough) system like NetBSD.	482	without API changes to existing programs. For this reason it's not being
		483	"auto-detected" unless you explicitly specify it in the flags (i.e. using
		484	C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough)
		485	system like NetBSD.
424		486
425	You still can embed kqueue into a normal poll or select backend and use it	487	You still can embed kqueue into a normal poll or select backend and use it
426	only for sockets (after having made sure that sockets work with kqueue on	488	only for sockets (after having made sure that sockets work with kqueue on
427	the target platform). See C<ev_embed> watchers for more info.	489	the target platform). See C<ev_embed> watchers for more info.
428		490
429	It scales in the same way as the epoll backend, but the interface to the	491	It scales in the same way as the epoll backend, but the interface to the
430	kernel is more efficient (which says nothing about its actual speed, of	492	kernel is more efficient (which says nothing about its actual speed, of
431	course). While stopping, setting and starting an I/O watcher does never	493	course). While stopping, setting and starting an I/O watcher does never
432	cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to	494	cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to
433	two event changes per incident. Support for C<fork ()> is very bad and it	495	two event changes per incident. Support for C<fork ()> is very bad (but
434	drops fds silently in similarly hard-to-detect cases.	496	sane, unlike epoll) and it drops fds silently in similarly hard-to-detect
		497	cases
435		498
436	This backend usually performs well under most conditions.	499	This backend usually performs well under most conditions.
437		500
438	While nominally embeddable in other event loops, this doesn't work	501	While nominally embeddable in other event loops, this doesn't work
439	everywhere, so you might need to test for this. And since it is broken	502	everywhere, so you might need to test for this. And since it is broken
440	almost everywhere, you should only use it when you have a lot of sockets	503	almost everywhere, you should only use it when you have a lot of sockets
441	(for which it usually works), by embedding it into another event loop	504	(for which it usually works), by embedding it into another event loop
442	(e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>) and, did I mention it,	505	(e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> (but C<poll> is of course
443	using it only for sockets.	506	also broken on OS X)) and, did I mention it, using it only for sockets.
444		507
445	This backend maps C<EV_READ> into an C<EVFILT_READ> kevent with	508	This backend maps C<EV_READ> into an C<EVFILT_READ> kevent with
446	C<NOTE_EOF>, and C<EV_WRITE> into an C<EVFILT_WRITE> kevent with	509	C<NOTE_EOF>, and C<EV_WRITE> into an C<EVFILT_WRITE> kevent with
447	C<NOTE_EOF>.	510	C<NOTE_EOF>.
448		511
…		…
468	might perform better.	531	might perform better.
469		532
470	On the positive side, with the exception of the spurious readiness	533	On the positive side, with the exception of the spurious readiness
471	notifications, this backend actually performed fully to specification	534	notifications, this backend actually performed fully to specification
472	in all tests and is fully embeddable, which is a rare feat among the	535	in all tests and is fully embeddable, which is a rare feat among the
473	OS-specific backends.	536	OS-specific backends (I vastly prefer correctness over speed hacks).
474		537
475	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as	538	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as
476	C<EVBACKEND_POLL>.	539	C<EVBACKEND_POLL>.
477		540
478	=item C<EVBACKEND_ALL>	541	=item C<EVBACKEND_ALL>
…		…
483		546
484	It is definitely not recommended to use this flag.	547	It is definitely not recommended to use this flag.
485		548
486	=back	549	=back
487		550
488	If one or more of these are or'ed into the flags value, then only these	551	If one or more of the backend flags are or'ed into the flags value,
489	backends will be tried (in the reverse order as listed here). If none are	552	then only these backends will be tried (in the reverse order as listed
490	specified, all backends in C<ev_recommended_backends ()> will be tried.	553	here). If none are specified, all backends in C<ev_recommended_backends
		554	()> will be tried.
491		555
492	Example: This is the most typical usage.	556	Example: This is the most typical usage.
493		557
494	if (!ev_default_loop (0))	558	if (!ev_default_loop (0))
495	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");	559	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
…		…
507	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);	571	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
508		572
509	=item struct ev_loop *ev_loop_new (unsigned int flags)	573	=item struct ev_loop *ev_loop_new (unsigned int flags)
510		574
511	Similar to C<ev_default_loop>, but always creates a new event loop that is	575	Similar to C<ev_default_loop>, but always creates a new event loop that is
512	always distinct from the default loop. Unlike the default loop, it cannot	576	always distinct from the default loop.
513	handle signal and child watchers, and attempts to do so will be greeted by
514	undefined behaviour (or a failed assertion if assertions are enabled).
515		577
516	Note that this function I<is> thread-safe, and the recommended way to use	578	Note that this function I<is> thread-safe, and one common way to use
517	libev with threads is indeed to create one loop per thread, and using the	579	libev with threads is indeed to create one loop per thread, and using the
518	default loop in the "main" or "initial" thread.	580	default loop in the "main" or "initial" thread.
519		581
520	Example: Try to create a event loop that uses epoll and nothing else.	582	Example: Try to create a event loop that uses epoll and nothing else.
521		583
…		…
523	if (!epoller)	585	if (!epoller)
524	fatal ("no epoll found here, maybe it hides under your chair");	586	fatal ("no epoll found here, maybe it hides under your chair");
525		587
526	=item ev_default_destroy ()	588	=item ev_default_destroy ()
527		589
528	Destroys the default loop again (frees all memory and kernel state	590	Destroys the default loop (frees all memory and kernel state etc.). None
529	etc.). None of the active event watchers will be stopped in the normal	591	of the active event watchers will be stopped in the normal sense, so
530	sense, so e.g. C<ev_is_active> might still return true. It is your	592	e.g. C<ev_is_active> might still return true. It is your responsibility to
531	responsibility to either stop all watchers cleanly yourself I<before>	593	either stop all watchers cleanly yourself I<before> calling this function,
532	calling this function, or cope with the fact afterwards (which is usually	594	or cope with the fact afterwards (which is usually the easiest thing, you
533	the easiest thing, you can just ignore the watchers and/or C<free ()> them	595	can just ignore the watchers and/or C<free ()> them for example).
534	for example).
535		596
536	Note that certain global state, such as signal state, will not be freed by	597	Note that certain global state, such as signal state (and installed signal
537	this function, and related watchers (such as signal and child watchers)	598	handlers), will not be freed by this function, and related watchers (such
538	would need to be stopped manually.	599	as signal and child watchers) would need to be stopped manually.
539		600
540	In general it is not advisable to call this function except in the	601	In general it is not advisable to call this function except in the
541	rare occasion where you really need to free e.g. the signal handling	602	rare occasion where you really need to free e.g. the signal handling
542	pipe fds. If you need dynamically allocated loops it is better to use	603	pipe fds. If you need dynamically allocated loops it is better to use
543	C<ev_loop_new> and C<ev_loop_destroy>).	604	C<ev_loop_new> and C<ev_loop_destroy>.
544		605
545	=item ev_loop_destroy (loop)	606	=item ev_loop_destroy (loop)
546		607
547	Like C<ev_default_destroy>, but destroys an event loop created by an	608	Like C<ev_default_destroy>, but destroys an event loop created by an
548	earlier call to C<ev_loop_new>.	609	earlier call to C<ev_loop_new>.
549		610
550	=item ev_default_fork ()	611	=item ev_default_fork ()
551		612
552	This function sets a flag that causes subsequent C<ev_loop> iterations	613	This function sets a flag that causes subsequent C<ev_run> iterations
553	to reinitialise the kernel state for backends that have one. Despite the	614	to reinitialise the kernel state for backends that have one. Despite the
554	name, you can call it anytime, but it makes most sense after forking, in	615	name, you can call it anytime, but it makes most sense after forking, in
555	the child process (or both child and parent, but that again makes little	616	the child process (or both child and parent, but that again makes little
556	sense). You I<must> call it in the child before using any of the libev	617	sense). You I<must> call it in the child before using any of the libev
557	functions, and it will only take effect at the next C<ev_loop> iteration.	618	functions, and it will only take effect at the next C<ev_run> iteration.
		619
		620	Again, you I<have> to call it on I<any> loop that you want to re-use after
		621	a fork, I<even if you do not plan to use the loop in the parent>. This is
		622	because some kernel interfaces *cough* I<kqueue> *cough* do funny things
		623	during fork.
558		624
559	On the other hand, you only need to call this function in the child	625	On the other hand, you only need to call this function in the child
560	process if and only if you want to use the event library in the child. If	626	process if and only if you want to use the event loop in the child. If
561	you just fork+exec, you don't have to call it at all.	627	you just fork+exec or create a new loop in the child, you don't have to
		628	call it at all (in fact, C<epoll> is so badly broken that it makes a
		629	difference, but libev will usually detect this case on its own and do a
		630	costly reset of the backend).
562		631
563	The function itself is quite fast and it's usually not a problem to call	632	The function itself is quite fast and it's usually not a problem to call
564	it just in case after a fork. To make this easy, the function will fit in	633	it just in case after a fork. To make this easy, the function will fit in
565	quite nicely into a call to C<pthread_atfork>:	634	quite nicely into a call to C<pthread_atfork>:
566		635
…		…
568		637
569	=item ev_loop_fork (loop)	638	=item ev_loop_fork (loop)
570		639
571	Like C<ev_default_fork>, but acts on an event loop created by	640	Like C<ev_default_fork>, but acts on an event loop created by
572	C<ev_loop_new>. Yes, you have to call this on every allocated event loop	641	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
573	after fork that you want to re-use in the child, and how you do this is	642	after fork that you want to re-use in the child, and how you keep track of
574	entirely your own problem.	643	them is entirely your own problem.
575		644
576	=item int ev_is_default_loop (loop)	645	=item int ev_is_default_loop (loop)
577		646
578	Returns true when the given loop is, in fact, the default loop, and false	647	Returns true when the given loop is, in fact, the default loop, and false
579	otherwise.	648	otherwise.
580		649
581	=item unsigned int ev_loop_count (loop)	650	=item unsigned int ev_iteration (loop)
582		651
583	Returns the count of loop iterations for the loop, which is identical to	652	Returns the current iteration count for the event loop, which is identical
584	the number of times libev did poll for new events. It starts at C<0> and	653	to the number of times libev did poll for new events. It starts at C<0>
585	happily wraps around with enough iterations.	654	and happily wraps around with enough iterations.
586		655
587	This value can sometimes be useful as a generation counter of sorts (it	656	This value can sometimes be useful as a generation counter of sorts (it
588	"ticks" the number of loop iterations), as it roughly corresponds with	657	"ticks" the number of loop iterations), as it roughly corresponds with
589	C<ev_prepare> and C<ev_check> calls.	658	C<ev_prepare> and C<ev_check> calls - and is incremented between the
		659	prepare and check phases.
		660
		661	=item unsigned int ev_depth (loop)
		662
		663	Returns the number of times C<ev_run> was entered minus the number of
		664	times C<ev_run> was exited, in other words, the recursion depth.
		665
		666	Outside C<ev_run>, this number is zero. In a callback, this number is
		667	C<1>, unless C<ev_run> was invoked recursively (or from another thread),
		668	in which case it is higher.
		669
		670	Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread
		671	etc.), doesn't count as "exit" - consider this as a hint to avoid such
		672	ungentleman-like behaviour unless it's really convenient.
590		673
591	=item unsigned int ev_backend (loop)	674	=item unsigned int ev_backend (loop)
592		675
593	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	676	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
594	use.	677	use.
…		…
603		686
604	=item ev_now_update (loop)	687	=item ev_now_update (loop)
605		688
606	Establishes the current time by querying the kernel, updating the time	689	Establishes the current time by querying the kernel, updating the time
607	returned by C<ev_now ()> in the progress. This is a costly operation and	690	returned by C<ev_now ()> in the progress. This is a costly operation and
608	is usually done automatically within C<ev_loop ()>.	691	is usually done automatically within C<ev_run ()>.
609		692
610	This function is rarely useful, but when some event callback runs for a	693	This function is rarely useful, but when some event callback runs for a
611	very long time without entering the event loop, updating libev's idea of	694	very long time without entering the event loop, updating libev's idea of
612	the current time is a good idea.	695	the current time is a good idea.
613		696
614	See also "The special problem of time updates" in the C<ev_timer> section.	697	See also L<The special problem of time updates> in the C<ev_timer> section.
615		698
		699	=item ev_suspend (loop)
		700
		701	=item ev_resume (loop)
		702
		703	These two functions suspend and resume an event loop, for use when the
		704	loop is not used for a while and timeouts should not be processed.
		705
		706	A typical use case would be an interactive program such as a game: When
		707	the user presses C<^Z> to suspend the game and resumes it an hour later it
		708	would be best to handle timeouts as if no time had actually passed while
		709	the program was suspended. This can be achieved by calling C<ev_suspend>
		710	in your C<SIGTSTP> handler, sending yourself a C<SIGSTOP> and calling
		711	C<ev_resume> directly afterwards to resume timer processing.
		712
		713	Effectively, all C<ev_timer> watchers will be delayed by the time spend
		714	between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers
		715	will be rescheduled (that is, they will lose any events that would have
		716	occurred while suspended).
		717
		718	After calling C<ev_suspend> you B<must not> call I<any> function on the
		719	given loop other than C<ev_resume>, and you B<must not> call C<ev_resume>
		720	without a previous call to C<ev_suspend>.
		721
		722	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the
		723	event loop time (see C<ev_now_update>).
		724
616	=item ev_loop (loop, int flags)	725	=item ev_run (loop, int flags)
617		726
618	Finally, this is it, the event handler. This function usually is called	727	Finally, this is it, the event handler. This function usually is called
619	after you initialised all your watchers and you want to start handling	728	after you have initialised all your watchers and you want to start
620	events.	729	handling events. It will ask the operating system for any new events, call
		730	the watcher callbacks, an then repeat the whole process indefinitely: This
		731	is why event loops are called I<loops>.
621		732
622	If the flags argument is specified as C<0>, it will not return until	733	If the flags argument is specified as C<0>, it will keep handling events
623	either no event watchers are active anymore or C<ev_unloop> was called.	734	until either no event watchers are active anymore or C<ev_break> was
		735	called.
624		736
625	Please note that an explicit C<ev_unloop> is usually better than	737	Please note that an explicit C<ev_break> is usually better than
626	relying on all watchers to be stopped when deciding when a program has	738	relying on all watchers to be stopped when deciding when a program has
627	finished (especially in interactive programs), but having a program	739	finished (especially in interactive programs), but having a program
628	that automatically loops as long as it has to and no longer by virtue	740	that automatically loops as long as it has to and no longer by virtue
629	of relying on its watchers stopping correctly, that is truly a thing of	741	of relying on its watchers stopping correctly, that is truly a thing of
630	beauty.	742	beauty.
631		743
632	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle	744	A flags value of C<EVRUN_NOWAIT> will look for new events, will handle
633	those events and any already outstanding ones, but will not block your	745	those events and any already outstanding ones, but will not wait and
634	process in case there are no events and will return after one iteration of	746	block your process in case there are no events and will return after one
635	the loop.	747	iteration of the loop. This is sometimes useful to poll and handle new
		748	events while doing lengthy calculations, to keep the program responsive.
636		749
637	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if	750	A flags value of C<EVRUN_ONCE> will look for new events (waiting if
638	necessary) and will handle those and any already outstanding ones. It	751	necessary) and will handle those and any already outstanding ones. It
639	will block your process until at least one new event arrives (which could	752	will block your process until at least one new event arrives (which could
640	be an event internal to libev itself, so there is no guarentee that a	753	be an event internal to libev itself, so there is no guarantee that a
641	user-registered callback will be called), and will return after one	754	user-registered callback will be called), and will return after one
642	iteration of the loop.	755	iteration of the loop.
643		756
644	This is useful if you are waiting for some external event in conjunction	757	This is useful if you are waiting for some external event in conjunction
645	with something not expressible using other libev watchers (i.e. "roll your	758	with something not expressible using other libev watchers (i.e. "roll your
646	own C<ev_loop>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is	759	own C<ev_run>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is
647	usually a better approach for this kind of thing.	760	usually a better approach for this kind of thing.
648		761
649	Here are the gory details of what C<ev_loop> does:	762	Here are the gory details of what C<ev_run> does:
650		763
		764	- Increment loop depth.
		765	- Reset the ev_break status.
651	- Before the first iteration, call any pending watchers.	766	- Before the first iteration, call any pending watchers.
		767	LOOP:
652	* If EVFLAG_FORKCHECK was used, check for a fork.	768	- If EVFLAG_FORKCHECK was used, check for a fork.
653	- If a fork was detected (by any means), queue and call all fork watchers.	769	- If a fork was detected (by any means), queue and call all fork watchers.
654	- Queue and call all prepare watchers.	770	- Queue and call all prepare watchers.
		771	- If ev_break was called, goto FINISH.
655	- If we have been forked, detach and recreate the kernel state	772	- If we have been forked, detach and recreate the kernel state
656	as to not disturb the other process.	773	as to not disturb the other process.
657	- Update the kernel state with all outstanding changes.	774	- Update the kernel state with all outstanding changes.
658	- Update the "event loop time" (ev_now ()).	775	- Update the "event loop time" (ev_now ()).
659	- Calculate for how long to sleep or block, if at all	776	- Calculate for how long to sleep or block, if at all
660	(active idle watchers, EVLOOP_NONBLOCK or not having	777	(active idle watchers, EVRUN_NOWAIT or not having
661	any active watchers at all will result in not sleeping).	778	any active watchers at all will result in not sleeping).
662	- Sleep if the I/O and timer collect interval say so.	779	- Sleep if the I/O and timer collect interval say so.
		780	- Increment loop iteration counter.
663	- Block the process, waiting for any events.	781	- Block the process, waiting for any events.
664	- Queue all outstanding I/O (fd) events.	782	- Queue all outstanding I/O (fd) events.
665	- Update the "event loop time" (ev_now ()), and do time jump adjustments.	783	- Update the "event loop time" (ev_now ()), and do time jump adjustments.
666	- Queue all expired timers.	784	- Queue all expired timers.
667	- Queue all expired periodics.	785	- Queue all expired periodics.
668	- Unless any events are pending now, queue all idle watchers.	786	- Queue all idle watchers with priority higher than that of pending events.
669	- Queue all check watchers.	787	- Queue all check watchers.
670	- Call all queued watchers in reverse order (i.e. check watchers first).	788	- Call all queued watchers in reverse order (i.e. check watchers first).
671	Signals and child watchers are implemented as I/O watchers, and will	789	Signals and child watchers are implemented as I/O watchers, and will
672	be handled here by queueing them when their watcher gets executed.	790	be handled here by queueing them when their watcher gets executed.
673	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	791	- If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT
674	were used, or there are no active watchers, return, otherwise	792	were used, or there are no active watchers, goto FINISH, otherwise
675	continue with step *.	793	continue with step LOOP.
		794	FINISH:
		795	- Reset the ev_break status iff it was EVBREAK_ONE.
		796	- Decrement the loop depth.
		797	- Return.
676		798
677	Example: Queue some jobs and then loop until no events are outstanding	799	Example: Queue some jobs and then loop until no events are outstanding
678	anymore.	800	anymore.
679		801
680	... queue jobs here, make sure they register event watchers as long	802	... queue jobs here, make sure they register event watchers as long
681	... as they still have work to do (even an idle watcher will do..)	803	... as they still have work to do (even an idle watcher will do..)
682	ev_loop (my_loop, 0);	804	ev_run (my_loop, 0);
683	... jobs done or somebody called unloop. yeah!	805	... jobs done or somebody called unloop. yeah!
684		806
685	=item ev_unloop (loop, how)	807	=item ev_break (loop, how)
686		808
687	Can be used to make a call to C<ev_loop> return early (but only after it	809	Can be used to make a call to C<ev_run> return early (but only after it
688	has processed all outstanding events). The C<how> argument must be either	810	has processed all outstanding events). The C<how> argument must be either
689	C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or	811	C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or
690	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.	812	C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return.
691		813
692	This "unloop state" will be cleared when entering C<ev_loop> again.	814	This "unloop state" will be cleared when entering C<ev_run> again.
693		815
694	It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls.	816	It is safe to call C<ev_break> from outside any C<ev_run> calls. ##TODO##
695		817
696	=item ev_ref (loop)	818	=item ev_ref (loop)
697		819
698	=item ev_unref (loop)	820	=item ev_unref (loop)
699		821
700	Ref/unref can be used to add or remove a reference count on the event	822	Ref/unref can be used to add or remove a reference count on the event
701	loop: Every watcher keeps one reference, and as long as the reference	823	loop: Every watcher keeps one reference, and as long as the reference
702	count is nonzero, C<ev_loop> will not return on its own.	824	count is nonzero, C<ev_run> will not return on its own.
703		825
704	If you have a watcher you never unregister that should not keep C<ev_loop>	826	This is useful when you have a watcher that you never intend to
705	from returning, call ev_unref() after starting, and ev_ref() before	827	unregister, but that nevertheless should not keep C<ev_run> from
		828	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>
706	stopping it.	829	before stopping it.
707		830
708	As an example, libev itself uses this for its internal signal pipe: It is	831	As an example, libev itself uses this for its internal signal pipe: It
709	not visible to the libev user and should not keep C<ev_loop> from exiting	832	is not visible to the libev user and should not keep C<ev_run> from
710	if no event watchers registered by it are active. It is also an excellent	833	exiting if no event watchers registered by it are active. It is also an
711	way to do this for generic recurring timers or from within third-party	834	excellent way to do this for generic recurring timers or from within
712	libraries. Just remember to I<unref after start> and I<ref before stop>	835	third-party libraries. Just remember to I<unref after start> and I<ref
713	(but only if the watcher wasn't active before, or was active before,	836	before stop> (but only if the watcher wasn't active before, or was active
714	respectively).	837	before, respectively. Note also that libev might stop watchers itself
		838	(e.g. non-repeating timers) in which case you have to C<ev_ref>
		839	in the callback).
715		840
716	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	841	Example: Create a signal watcher, but keep it from keeping C<ev_run>
717	running when nothing else is active.	842	running when nothing else is active.
718		843
719	ev_signal exitsig;	844	ev_signal exitsig;
720	ev_signal_init (&exitsig, sig_cb, SIGINT);	845	ev_signal_init (&exitsig, sig_cb, SIGINT);
721	ev_signal_start (loop, &exitsig);	846	ev_signal_start (loop, &exitsig);
…		…
748		873
749	By setting a higher I<io collect interval> you allow libev to spend more	874	By setting a higher I<io collect interval> you allow libev to spend more
750	time collecting I/O events, so you can handle more events per iteration,	875	time collecting I/O events, so you can handle more events per iteration,
751	at the cost of increasing latency. Timeouts (both C<ev_periodic> and	876	at the cost of increasing latency. Timeouts (both C<ev_periodic> and
752	C<ev_timer>) will be not affected. Setting this to a non-null value will	877	C<ev_timer>) will be not affected. Setting this to a non-null value will
753	introduce an additional C<ev_sleep ()> call into most loop iterations.	878	introduce an additional C<ev_sleep ()> call into most loop iterations. The
		879	sleep time ensures that libev will not poll for I/O events more often then
		880	once per this interval, on average.
754		881
755	Likewise, by setting a higher I<timeout collect interval> you allow libev	882	Likewise, by setting a higher I<timeout collect interval> you allow libev
756	to spend more time collecting timeouts, at the expense of increased	883	to spend more time collecting timeouts, at the expense of increased
757	latency/jitter/inexactness (the watcher callback will be called	884	latency/jitter/inexactness (the watcher callback will be called
758	later). C<ev_io> watchers will not be affected. Setting this to a non-null	885	later). C<ev_io> watchers will not be affected. Setting this to a non-null
…		…
760		887
761	Many (busy) programs can usually benefit by setting the I/O collect	888	Many (busy) programs can usually benefit by setting the I/O collect
762	interval to a value near C<0.1> or so, which is often enough for	889	interval to a value near C<0.1> or so, which is often enough for
763	interactive servers (of course not for games), likewise for timeouts. It	890	interactive servers (of course not for games), likewise for timeouts. It
764	usually doesn't make much sense to set it to a lower value than C<0.01>,	891	usually doesn't make much sense to set it to a lower value than C<0.01>,
765	as this approaches the timing granularity of most systems.	892	as this approaches the timing granularity of most systems. Note that if
		893	you do transactions with the outside world and you can't increase the
		894	parallelity, then this setting will limit your transaction rate (if you
		895	need to poll once per transaction and the I/O collect interval is 0.01,
		896	then you can't do more than 100 transactions per second).
766		897
767	Setting the I<timeout collect interval> can improve the opportunity for	898	Setting the I<timeout collect interval> can improve the opportunity for
768	saving power, as the program will "bundle" timer callback invocations that	899	saving power, as the program will "bundle" timer callback invocations that
769	are "near" in time together, by delaying some, thus reducing the number of	900	are "near" in time together, by delaying some, thus reducing the number of
770	times the process sleeps and wakes up again. Another useful technique to	901	times the process sleeps and wakes up again. Another useful technique to
771	reduce iterations/wake-ups is to use C<ev_periodic> watchers and make sure	902	reduce iterations/wake-ups is to use C<ev_periodic> watchers and make sure
772	they fire on, say, one-second boundaries only.	903	they fire on, say, one-second boundaries only.
773		904
		905	Example: we only need 0.1s timeout granularity, and we wish not to poll
		906	more often than 100 times per second:
		907
		908	ev_set_timeout_collect_interval (EV_DEFAULT_UC_ 0.1);
		909	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);
		910
		911	=item ev_invoke_pending (loop)
		912
		913	This call will simply invoke all pending watchers while resetting their
		914	pending state. Normally, C<ev_run> does this automatically when required,
		915	but when overriding the invoke callback this call comes handy. This
		916	function can be invoked from a watcher - this can be useful for example
		917	when you want to do some lengthy calculation and want to pass further
		918	event handling to another thread (you still have to make sure only one
		919	thread executes within C<ev_invoke_pending> or C<ev_run> of course).
		920
		921	=item int ev_pending_count (loop)
		922
		923	Returns the number of pending watchers - zero indicates that no watchers
		924	are pending.
		925
		926	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))
		927
		928	This overrides the invoke pending functionality of the loop: Instead of
		929	invoking all pending watchers when there are any, C<ev_run> will call
		930	this callback instead. This is useful, for example, when you want to
		931	invoke the actual watchers inside another context (another thread etc.).
		932
		933	If you want to reset the callback, use C<ev_invoke_pending> as new
		934	callback.
		935
		936	=item ev_set_loop_release_cb (loop, void (*release)(EV_P), void (*acquire)(EV_P))
		937
		938	Sometimes you want to share the same loop between multiple threads. This
		939	can be done relatively simply by putting mutex_lock/unlock calls around
		940	each call to a libev function.
		941
		942	However, C<ev_run> can run an indefinite time, so it is not feasible
		943	to wait for it to return. One way around this is to wake up the event
		944	loop via C<ev_break> and C<av_async_send>, another way is to set these
		945	I<release> and I<acquire> callbacks on the loop.
		946
		947	When set, then C<release> will be called just before the thread is
		948	suspended waiting for new events, and C<acquire> is called just
		949	afterwards.
		950
		951	Ideally, C<release> will just call your mutex_unlock function, and
		952	C<acquire> will just call the mutex_lock function again.
		953
		954	While event loop modifications are allowed between invocations of
		955	C<release> and C<acquire> (that's their only purpose after all), no
		956	modifications done will affect the event loop, i.e. adding watchers will
		957	have no effect on the set of file descriptors being watched, or the time
		958	waited. Use an C<ev_async> watcher to wake up C<ev_run> when you want it
		959	to take note of any changes you made.
		960
		961	In theory, threads executing C<ev_run> will be async-cancel safe between
		962	invocations of C<release> and C<acquire>.
		963
		964	See also the locking example in the C<THREADS> section later in this
		965	document.
		966
		967	=item ev_set_userdata (loop, void *data)
		968
		969	=item ev_userdata (loop)
		970
		971	Set and retrieve a single C<void *> associated with a loop. When
		972	C<ev_set_userdata> has never been called, then C<ev_userdata> returns
		973	C<0.>
		974
		975	These two functions can be used to associate arbitrary data with a loop,
		976	and are intended solely for the C<invoke_pending_cb>, C<release> and
		977	C<acquire> callbacks described above, but of course can be (ab-)used for
		978	any other purpose as well.
		979
774	=item ev_loop_verify (loop)	980	=item ev_verify (loop)
775		981
776	This function only does something when C<EV_VERIFY> support has been	982	This function only does something when C<EV_VERIFY> support has been
777	compiled in, which is the default for non-minimal builds. It tries to go	983	compiled in, which is the default for non-minimal builds. It tries to go
778	through all internal structures and checks them for validity. If anything	984	through all internal structures and checks them for validity. If anything
779	is found to be inconsistent, it will print an error message to standard	985	is found to be inconsistent, it will print an error message to standard
…		…
790		996
791	In the following description, uppercase C<TYPE> in names stands for the	997	In the following description, uppercase C<TYPE> in names stands for the
792	watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer	998	watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer
793	watchers and C<ev_io_start> for I/O watchers.	999	watchers and C<ev_io_start> for I/O watchers.
794		1000
795	A watcher is a structure that you create and register to record your	1001	A watcher is an opaque structure that you allocate and register to record
796	interest in some event. For instance, if you want to wait for STDIN to	1002	your interest in some event. To make a concrete example, imagine you want
797	become readable, you would create an C<ev_io> watcher for that:	1003	to wait for STDIN to become readable, you would create an C<ev_io> watcher
		1004	for that:
798		1005
799	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)	1006	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)
800	{	1007	{
801	ev_io_stop (w);	1008	ev_io_stop (w);
802	ev_unloop (loop, EVUNLOOP_ALL);	1009	ev_break (loop, EVBREAK_ALL);
803	}	1010	}
804		1011
805	struct ev_loop *loop = ev_default_loop (0);	1012	struct ev_loop *loop = ev_default_loop (0);
806		1013
807	ev_io stdin_watcher;	1014	ev_io stdin_watcher;
808		1015
809	ev_init (&stdin_watcher, my_cb);	1016	ev_init (&stdin_watcher, my_cb);
810	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	1017	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
811	ev_io_start (loop, &stdin_watcher);	1018	ev_io_start (loop, &stdin_watcher);
812		1019
813	ev_loop (loop, 0);	1020	ev_run (loop, 0);
814		1021
815	As you can see, you are responsible for allocating the memory for your	1022	As you can see, you are responsible for allocating the memory for your
816	watcher structures (and it is I<usually> a bad idea to do this on the	1023	watcher structures (and it is I<usually> a bad idea to do this on the
817	stack).	1024	stack).
818		1025
819	Each watcher has an associated watcher structure (called C<struct ev_TYPE>	1026	Each watcher has an associated watcher structure (called C<struct ev_TYPE>
820	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).	1027	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).
821		1028
822	Each watcher structure must be initialised by a call to C<ev_init	1029	Each watcher structure must be initialised by a call to C<ev_init (watcher
823	(watcher *, callback)>, which expects a callback to be provided. This	1030	*, callback)>, which expects a callback to be provided. This callback is
824	callback gets invoked each time the event occurs (or, in the case of I/O	1031	invoked each time the event occurs (or, in the case of I/O watchers, each
825	watchers, each time the event loop detects that the file descriptor given	1032	time the event loop detects that the file descriptor given is readable
826	is readable and/or writable).	1033	and/or writable).
827		1034
828	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>	1035	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>
829	macro to configure it, with arguments specific to the watcher type. There	1036	macro to configure it, with arguments specific to the watcher type. There
830	is also a macro to combine initialisation and setting in one call: C<<	1037	is also a macro to combine initialisation and setting in one call: C<<
831	ev_TYPE_init (watcher *, callback, ...) >>.	1038	ev_TYPE_init (watcher *, callback, ...) >>.
…		…
854	=item C<EV_WRITE>	1061	=item C<EV_WRITE>
855		1062
856	The file descriptor in the C<ev_io> watcher has become readable and/or	1063	The file descriptor in the C<ev_io> watcher has become readable and/or
857	writable.	1064	writable.
858		1065
859	=item C<EV_TIMEOUT>	1066	=item C<EV_TIMER>
860		1067
861	The C<ev_timer> watcher has timed out.	1068	The C<ev_timer> watcher has timed out.
862		1069
863	=item C<EV_PERIODIC>	1070	=item C<EV_PERIODIC>
864		1071
…		…
882		1089
883	=item C<EV_PREPARE>	1090	=item C<EV_PREPARE>
884		1091
885	=item C<EV_CHECK>	1092	=item C<EV_CHECK>
886		1093
887	All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts	1094	All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts
888	to gather new events, and all C<ev_check> watchers are invoked just after	1095	to gather new events, and all C<ev_check> watchers are invoked just after
889	C<ev_loop> has gathered them, but before it invokes any callbacks for any	1096	C<ev_run> has gathered them, but before it invokes any callbacks for any
890	received events. Callbacks of both watcher types can start and stop as	1097	received events. Callbacks of both watcher types can start and stop as
891	many watchers as they want, and all of them will be taken into account	1098	many watchers as they want, and all of them will be taken into account
892	(for example, a C<ev_prepare> watcher might start an idle watcher to keep	1099	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
893	C<ev_loop> from blocking).	1100	C<ev_run> from blocking).
894		1101
895	=item C<EV_EMBED>	1102	=item C<EV_EMBED>
896		1103
897	The embedded event loop specified in the C<ev_embed> watcher needs attention.	1104	The embedded event loop specified in the C<ev_embed> watcher needs attention.
898		1105
…		…
902	C<ev_fork>).	1109	C<ev_fork>).
903		1110
904	=item C<EV_ASYNC>	1111	=item C<EV_ASYNC>
905		1112
906	The given async watcher has been asynchronously notified (see C<ev_async>).	1113	The given async watcher has been asynchronously notified (see C<ev_async>).
		1114
		1115	=item C<EV_CUSTOM>
		1116
		1117	Not ever sent (or otherwise used) by libev itself, but can be freely used
		1118	by libev users to signal watchers (e.g. via C<ev_feed_event>).
907		1119
908	=item C<EV_ERROR>	1120	=item C<EV_ERROR>
909		1121
910	An unspecified error has occurred, the watcher has been stopped. This might	1122	An unspecified error has occurred, the watcher has been stopped. This might
911	happen because the watcher could not be properly started because libev	1123	happen because the watcher could not be properly started because libev
…		…
924	programs, though, as the fd could already be closed and reused for another	1136	programs, though, as the fd could already be closed and reused for another
925	thing, so beware.	1137	thing, so beware.
926		1138
927	=back	1139	=back
928		1140
		1141	=head2 WATCHER STATES
		1142
		1143	There are various watcher states mentioned throughout this manual -
		1144	active, pending and so on. In this section these states and the rules to
		1145	transition between them will be described in more detail - and while these
		1146	rules might look complicated, they usually do "the right thing".
		1147
		1148	=over 4
		1149
		1150	=item initialiased
		1151
		1152	Before a watcher can be registered with the event looop it has to be
		1153	initialised. This can be done with a call to C<ev_TYPE_init>, or calls to
		1154	C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function.
		1155
		1156	In this state it is simply some block of memory that is suitable for use
		1157	in an event loop. It can be moved around, freed, reused etc. at will.
		1158
		1159	=item started/running/active
		1160
		1161	Once a watcher has been started with a call to C<ev_TYPE_start> it becomes
		1162	property of the event loop, and is actively waiting for events. While in
		1163	this state it cannot be accessed (except in a few documented ways), moved,
		1164	freed or anything else - the only legal thing is to keep a pointer to it,
		1165	and call libev functions on it that are documented to work on active watchers.
		1166
		1167	=item pending
		1168
		1169	If a watcher is active and libev determines that an event it is interested
		1170	in has occurred (such as a timer expiring), it will become pending. It will
		1171	stay in this pending state until either it is stopped or its callback is
		1172	about to be invoked, so it is not normally pending inside the watcher
		1173	callback.
		1174
		1175	The watcher might or might not be active while it is pending (for example,
		1176	an expired non-repeating timer can be pending but no longer active). If it
		1177	is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>),
		1178	but it is still property of the event loop at this time, so cannot be
		1179	moved, freed or reused. And if it is active the rules described in the
		1180	previous item still apply.
		1181
		1182	It is also possible to feed an event on a watcher that is not active (e.g.
		1183	via C<ev_feed_event>), in which case it becomes pending without being
		1184	active.
		1185
		1186	=item stopped
		1187
		1188	A watcher can be stopped implicitly by libev (in which case it might still
		1189	be pending), or explicitly by calling its C<ev_TYPE_stop> function. The
		1190	latter will clear any pending state the watcher might be in, regardless
		1191	of whether it was active or not, so stopping a watcher explicitly before
		1192	freeing it is often a good idea.
		1193
		1194	While stopped (and not pending) the watcher is essentially in the
		1195	initialised state, that is it can be reused, moved, modified in any way
		1196	you wish.
		1197
		1198	=back
		1199
929	=head2 GENERIC WATCHER FUNCTIONS	1200	=head2 GENERIC WATCHER FUNCTIONS
930		1201
931	=over 4	1202	=over 4
932		1203
933	=item C<ev_init> (ev_TYPE *watcher, callback)	1204	=item C<ev_init> (ev_TYPE *watcher, callback)
…		…
949		1220
950	ev_io w;	1221	ev_io w;
951	ev_init (&w, my_cb);	1222	ev_init (&w, my_cb);
952	ev_io_set (&w, STDIN_FILENO, EV_READ);	1223	ev_io_set (&w, STDIN_FILENO, EV_READ);
953		1224
954	=item C<ev_TYPE_set> (ev_TYPE *, [args])	1225	=item C<ev_TYPE_set> (ev_TYPE *watcher, [args])
955		1226
956	This macro initialises the type-specific parts of a watcher. You need to	1227	This macro initialises the type-specific parts of a watcher. You need to
957	call C<ev_init> at least once before you call this macro, but you can	1228	call C<ev_init> at least once before you call this macro, but you can
958	call C<ev_TYPE_set> any number of times. You must not, however, call this	1229	call C<ev_TYPE_set> any number of times. You must not, however, call this
959	macro on a watcher that is active (it can be pending, however, which is a	1230	macro on a watcher that is active (it can be pending, however, which is a
…		…
972		1243
973	Example: Initialise and set an C<ev_io> watcher in one step.	1244	Example: Initialise and set an C<ev_io> watcher in one step.
974		1245
975	ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ);	1246	ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ);
976		1247
977	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)	1248	=item C<ev_TYPE_start> (loop, ev_TYPE *watcher)
978		1249
979	Starts (activates) the given watcher. Only active watchers will receive	1250	Starts (activates) the given watcher. Only active watchers will receive
980	events. If the watcher is already active nothing will happen.	1251	events. If the watcher is already active nothing will happen.
981		1252
982	Example: Start the C<ev_io> watcher that is being abused as example in this	1253	Example: Start the C<ev_io> watcher that is being abused as example in this
983	whole section.	1254	whole section.
984		1255
985	ev_io_start (EV_DEFAULT_UC, &w);	1256	ev_io_start (EV_DEFAULT_UC, &w);
986		1257
987	=item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher)	1258	=item C<ev_TYPE_stop> (loop, ev_TYPE *watcher)
988		1259
989	Stops the given watcher if active, and clears the pending status (whether	1260	Stops the given watcher if active, and clears the pending status (whether
990	the watcher was active or not).	1261	the watcher was active or not).
991		1262
992	It is possible that stopped watchers are pending - for example,	1263	It is possible that stopped watchers are pending - for example,
…		…
1017	=item ev_cb_set (ev_TYPE *watcher, callback)	1288	=item ev_cb_set (ev_TYPE *watcher, callback)
1018		1289
1019	Change the callback. You can change the callback at virtually any time	1290	Change the callback. You can change the callback at virtually any time
1020	(modulo threads).	1291	(modulo threads).
1021		1292
1022	=item ev_set_priority (ev_TYPE *watcher, priority)	1293	=item ev_set_priority (ev_TYPE *watcher, int priority)
1023		1294
1024	=item int ev_priority (ev_TYPE *watcher)	1295	=item int ev_priority (ev_TYPE *watcher)
1025		1296
1026	Set and query the priority of the watcher. The priority is a small	1297	Set and query the priority of the watcher. The priority is a small
1027	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>	1298	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>
1028	(default: C<-2>). Pending watchers with higher priority will be invoked	1299	(default: C<-2>). Pending watchers with higher priority will be invoked
1029	before watchers with lower priority, but priority will not keep watchers	1300	before watchers with lower priority, but priority will not keep watchers
1030	from being executed (except for C<ev_idle> watchers).	1301	from being executed (except for C<ev_idle> watchers).
1031		1302
1032	This means that priorities are I<only> used for ordering callback
1033	invocation after new events have been received. This is useful, for
1034	example, to reduce latency after idling, or more often, to bind two
1035	watchers on the same event and make sure one is called first.
1036
1037	If you need to suppress invocation when higher priority events are pending	1303	If you need to suppress invocation when higher priority events are pending
1038	you need to look at C<ev_idle> watchers, which provide this functionality.	1304	you need to look at C<ev_idle> watchers, which provide this functionality.
1039		1305
1040	You I<must not> change the priority of a watcher as long as it is active or	1306	You I<must not> change the priority of a watcher as long as it is active or
1041	pending.	1307	pending.
1042
1043	The default priority used by watchers when no priority has been set is
1044	always C<0>, which is supposed to not be too high and not be too low :).
1045		1308
1046	Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is	1309	Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is
1047	fine, as long as you do not mind that the priority value you query might	1310	fine, as long as you do not mind that the priority value you query might
1048	or might not have been clamped to the valid range.	1311	or might not have been clamped to the valid range.
		1312
		1313	The default priority used by watchers when no priority has been set is
		1314	always C<0>, which is supposed to not be too high and not be too low :).
		1315
		1316	See L<WATCHER PRIORITY MODELS>, below, for a more thorough treatment of
		1317	priorities.
1049		1318
1050	=item ev_invoke (loop, ev_TYPE *watcher, int revents)	1319	=item ev_invoke (loop, ev_TYPE *watcher, int revents)
1051		1320
1052	Invoke the C<watcher> with the given C<loop> and C<revents>. Neither	1321	Invoke the C<watcher> with the given C<loop> and C<revents>. Neither
1053	C<loop> nor C<revents> need to be valid as long as the watcher callback	1322	C<loop> nor C<revents> need to be valid as long as the watcher callback
…		…
1060	returns its C<revents> bitset (as if its callback was invoked). If the	1329	returns its C<revents> bitset (as if its callback was invoked). If the
1061	watcher isn't pending it does nothing and returns C<0>.	1330	watcher isn't pending it does nothing and returns C<0>.
1062		1331
1063	Sometimes it can be useful to "poll" a watcher instead of waiting for its	1332	Sometimes it can be useful to "poll" a watcher instead of waiting for its
1064	callback to be invoked, which can be accomplished with this function.	1333	callback to be invoked, which can be accomplished with this function.
		1334
		1335	=item ev_feed_event (loop, ev_TYPE *watcher, int revents)
		1336
		1337	Feeds the given event set into the event loop, as if the specified event
		1338	had happened for the specified watcher (which must be a pointer to an
		1339	initialised but not necessarily started event watcher). Obviously you must
		1340	not free the watcher as long as it has pending events.
		1341
		1342	Stopping the watcher, letting libev invoke it, or calling
		1343	C<ev_clear_pending> will clear the pending event, even if the watcher was
		1344	not started in the first place.
		1345
		1346	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related
		1347	functions that do not need a watcher.
1065		1348
1066	=back	1349	=back
1067		1350
1068		1351
1069	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	1352	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
1118	#include <stddef.h>	1401	#include <stddef.h>
1119		1402
1120	static void	1403	static void
1121	t1_cb (EV_P_ ev_timer *w, int revents)	1404	t1_cb (EV_P_ ev_timer *w, int revents)
1122	{	1405	{
1123	struct my_biggy big = (struct my_biggy *	1406	struct my_biggy big = (struct my_biggy *)
1124	(((char *)w) - offsetof (struct my_biggy, t1));	1407	(((char *)w) - offsetof (struct my_biggy, t1));
1125	}	1408	}
1126		1409
1127	static void	1410	static void
1128	t2_cb (EV_P_ ev_timer *w, int revents)	1411	t2_cb (EV_P_ ev_timer *w, int revents)
1129	{	1412	{
1130	struct my_biggy big = (struct my_biggy *	1413	struct my_biggy big = (struct my_biggy *)
1131	(((char *)w) - offsetof (struct my_biggy, t2));	1414	(((char *)w) - offsetof (struct my_biggy, t2));
1132	}	1415	}
		1416
		1417	=head2 WATCHER PRIORITY MODELS
		1418
		1419	Many event loops support I<watcher priorities>, which are usually small
		1420	integers that influence the ordering of event callback invocation
		1421	between watchers in some way, all else being equal.
		1422
		1423	In libev, Watcher priorities can be set using C<ev_set_priority>. See its
		1424	description for the more technical details such as the actual priority
		1425	range.
		1426
		1427	There are two common ways how these these priorities are being interpreted
		1428	by event loops:
		1429
		1430	In the more common lock-out model, higher priorities "lock out" invocation
		1431	of lower priority watchers, which means as long as higher priority
		1432	watchers receive events, lower priority watchers are not being invoked.
		1433
		1434	The less common only-for-ordering model uses priorities solely to order
		1435	callback invocation within a single event loop iteration: Higher priority
		1436	watchers are invoked before lower priority ones, but they all get invoked
		1437	before polling for new events.
		1438
		1439	Libev uses the second (only-for-ordering) model for all its watchers
		1440	except for idle watchers (which use the lock-out model).
		1441
		1442	The rationale behind this is that implementing the lock-out model for
		1443	watchers is not well supported by most kernel interfaces, and most event
		1444	libraries will just poll for the same events again and again as long as
		1445	their callbacks have not been executed, which is very inefficient in the
		1446	common case of one high-priority watcher locking out a mass of lower
		1447	priority ones.
		1448
		1449	Static (ordering) priorities are most useful when you have two or more
		1450	watchers handling the same resource: a typical usage example is having an
		1451	C<ev_io> watcher to receive data, and an associated C<ev_timer> to handle
		1452	timeouts. Under load, data might be received while the program handles
		1453	other jobs, but since timers normally get invoked first, the timeout
		1454	handler will be executed before checking for data. In that case, giving
		1455	the timer a lower priority than the I/O watcher ensures that I/O will be
		1456	handled first even under adverse conditions (which is usually, but not
		1457	always, what you want).
		1458
		1459	Since idle watchers use the "lock-out" model, meaning that idle watchers
		1460	will only be executed when no same or higher priority watchers have
		1461	received events, they can be used to implement the "lock-out" model when
		1462	required.
		1463
		1464	For example, to emulate how many other event libraries handle priorities,
		1465	you can associate an C<ev_idle> watcher to each such watcher, and in
		1466	the normal watcher callback, you just start the idle watcher. The real
		1467	processing is done in the idle watcher callback. This causes libev to
		1468	continuously poll and process kernel event data for the watcher, but when
		1469	the lock-out case is known to be rare (which in turn is rare :), this is
		1470	workable.
		1471
		1472	Usually, however, the lock-out model implemented that way will perform
		1473	miserably under the type of load it was designed to handle. In that case,
		1474	it might be preferable to stop the real watcher before starting the
		1475	idle watcher, so the kernel will not have to process the event in case
		1476	the actual processing will be delayed for considerable time.
		1477
		1478	Here is an example of an I/O watcher that should run at a strictly lower
		1479	priority than the default, and which should only process data when no
		1480	other events are pending:
		1481
		1482	ev_idle idle; // actual processing watcher
		1483	ev_io io; // actual event watcher
		1484
		1485	static void
		1486	io_cb (EV_P_ ev_io *w, int revents)
		1487	{
		1488	// stop the I/O watcher, we received the event, but
		1489	// are not yet ready to handle it.
		1490	ev_io_stop (EV_A_ w);
		1491
		1492	// start the idle watcher to handle the actual event.
		1493	// it will not be executed as long as other watchers
		1494	// with the default priority are receiving events.
		1495	ev_idle_start (EV_A_ &idle);
		1496	}
		1497
		1498	static void
		1499	idle_cb (EV_P_ ev_idle *w, int revents)
		1500	{
		1501	// actual processing
		1502	read (STDIN_FILENO, ...);
		1503
		1504	// have to start the I/O watcher again, as
		1505	// we have handled the event
		1506	ev_io_start (EV_P_ &io);
		1507	}
		1508
		1509	// initialisation
		1510	ev_idle_init (&idle, idle_cb);
		1511	ev_io_init (&io, io_cb, STDIN_FILENO, EV_READ);
		1512	ev_io_start (EV_DEFAULT_ &io);
		1513
		1514	In the "real" world, it might also be beneficial to start a timer, so that
		1515	low-priority connections can not be locked out forever under load. This
		1516	enables your program to keep a lower latency for important connections
		1517	during short periods of high load, while not completely locking out less
		1518	important ones.
1133		1519
1134		1520
1135	=head1 WATCHER TYPES	1521	=head1 WATCHER TYPES
1136		1522
1137	This section describes each watcher in detail, but will not repeat	1523	This section describes each watcher in detail, but will not repeat
…		…
1163	descriptors to non-blocking mode is also usually a good idea (but not	1549	descriptors to non-blocking mode is also usually a good idea (but not
1164	required if you know what you are doing).	1550	required if you know what you are doing).
1165		1551
1166	If you cannot use non-blocking mode, then force the use of a	1552	If you cannot use non-blocking mode, then force the use of a
1167	known-to-be-good backend (at the time of this writing, this includes only	1553	known-to-be-good backend (at the time of this writing, this includes only
1168	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>).	1554	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file
		1555	descriptors for which non-blocking operation makes no sense (such as
		1556	files) - libev doesn't guarantee any specific behaviour in that case.
1169		1557
1170	Another thing you have to watch out for is that it is quite easy to	1558	Another thing you have to watch out for is that it is quite easy to
1171	receive "spurious" readiness notifications, that is your callback might	1559	receive "spurious" readiness notifications, that is your callback might
1172	be called with C<EV_READ> but a subsequent C<read>(2) will actually block	1560	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
1173	because there is no data. Not only are some backends known to create a	1561	because there is no data. Not only are some backends known to create a
…		…
1238		1626
1239	So when you encounter spurious, unexplained daemon exits, make sure you	1627	So when you encounter spurious, unexplained daemon exits, make sure you
1240	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon	1628	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon
1241	somewhere, as that would have given you a big clue).	1629	somewhere, as that would have given you a big clue).
1242		1630
		1631	=head3 The special problem of accept()ing when you can't
		1632
		1633	Many implementations of the POSIX C<accept> function (for example,
		1634	found in post-2004 Linux) have the peculiar behaviour of not removing a
		1635	connection from the pending queue in all error cases.
		1636
		1637	For example, larger servers often run out of file descriptors (because
		1638	of resource limits), causing C<accept> to fail with C<ENFILE> but not
		1639	rejecting the connection, leading to libev signalling readiness on
		1640	the next iteration again (the connection still exists after all), and
		1641	typically causing the program to loop at 100% CPU usage.
		1642
		1643	Unfortunately, the set of errors that cause this issue differs between
		1644	operating systems, there is usually little the app can do to remedy the
		1645	situation, and no known thread-safe method of removing the connection to
		1646	cope with overload is known (to me).
		1647
		1648	One of the easiest ways to handle this situation is to just ignore it
		1649	- when the program encounters an overload, it will just loop until the
		1650	situation is over. While this is a form of busy waiting, no OS offers an
		1651	event-based way to handle this situation, so it's the best one can do.
		1652
		1653	A better way to handle the situation is to log any errors other than
		1654	C<EAGAIN> and C<EWOULDBLOCK>, making sure not to flood the log with such
		1655	messages, and continue as usual, which at least gives the user an idea of
		1656	what could be wrong ("raise the ulimit!"). For extra points one could stop
		1657	the C<ev_io> watcher on the listening fd "for a while", which reduces CPU
		1658	usage.
		1659
		1660	If your program is single-threaded, then you could also keep a dummy file
		1661	descriptor for overload situations (e.g. by opening F</dev/null>), and
		1662	when you run into C<ENFILE> or C<EMFILE>, close it, run C<accept>,
		1663	close that fd, and create a new dummy fd. This will gracefully refuse
		1664	clients under typical overload conditions.
		1665
		1666	The last way to handle it is to simply log the error and C<exit>, as
		1667	is often done with C<malloc> failures, but this results in an easy
		1668	opportunity for a DoS attack.
1243		1669
1244	=head3 Watcher-Specific Functions	1670	=head3 Watcher-Specific Functions
1245		1671
1246	=over 4	1672	=over 4
1247		1673
…		…
1279	...	1705	...
1280	struct ev_loop *loop = ev_default_init (0);	1706	struct ev_loop *loop = ev_default_init (0);
1281	ev_io stdin_readable;	1707	ev_io stdin_readable;
1282	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1708	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1283	ev_io_start (loop, &stdin_readable);	1709	ev_io_start (loop, &stdin_readable);
1284	ev_loop (loop, 0);	1710	ev_run (loop, 0);
1285		1711
1286		1712
1287	=head2 C<ev_timer> - relative and optionally repeating timeouts	1713	=head2 C<ev_timer> - relative and optionally repeating timeouts
1288		1714
1289	Timer watchers are simple relative timers that generate an event after a	1715	Timer watchers are simple relative timers that generate an event after a
…		…
1294	year, it will still time out after (roughly) one hour. "Roughly" because	1720	year, it will still time out after (roughly) one hour. "Roughly" because
1295	detecting time jumps is hard, and some inaccuracies are unavoidable (the	1721	detecting time jumps is hard, and some inaccuracies are unavoidable (the
1296	monotonic clock option helps a lot here).	1722	monotonic clock option helps a lot here).
1297		1723
1298	The callback is guaranteed to be invoked only I<after> its timeout has	1724	The callback is guaranteed to be invoked only I<after> its timeout has
1299	passed, but if multiple timers become ready during the same loop iteration	1725	passed (not I<at>, so on systems with very low-resolution clocks this
1300	then order of execution is undefined.	1726	might introduce a small delay). If multiple timers become ready during the
		1727	same loop iteration then the ones with earlier time-out values are invoked
		1728	before ones of the same priority with later time-out values (but this is
		1729	no longer true when a callback calls C<ev_run> recursively).
1301		1730
1302	=head3 Be smart about timeouts	1731	=head3 Be smart about timeouts
1303		1732
1304	Many real-world problems involve some kind of timeout, usually for error	1733	Many real-world problems involve some kind of timeout, usually for error
1305	recovery. A typical example is an HTTP request - if the other side hangs,	1734	recovery. A typical example is an HTTP request - if the other side hangs,
…		…
1349	C<after> argument to C<ev_timer_set>, and only ever use the C<repeat>	1778	C<after> argument to C<ev_timer_set>, and only ever use the C<repeat>
1350	member and C<ev_timer_again>.	1779	member and C<ev_timer_again>.
1351		1780
1352	At start:	1781	At start:
1353		1782
1354	ev_timer_init (timer, callback);	1783	ev_init (timer, callback);
1355	timer->repeat = 60.;	1784	timer->repeat = 60.;
1356	ev_timer_again (loop, timer);	1785	ev_timer_again (loop, timer);
1357		1786
1358	Each time there is some activity:	1787	Each time there is some activity:
1359		1788
…		…
1391	ev_tstamp timeout = last_activity + 60.;	1820	ev_tstamp timeout = last_activity + 60.;
1392		1821
1393	// if last_activity + 60. is older than now, we did time out	1822	// if last_activity + 60. is older than now, we did time out
1394	if (timeout < now)	1823	if (timeout < now)
1395	{	1824	{
1396	// timeout occured, take action	1825	// timeout occurred, take action
1397	}	1826	}
1398	else	1827	else
1399	{	1828	{
1400	// callback was invoked, but there was some activity, re-arm	1829	// callback was invoked, but there was some activity, re-arm
1401	// the watcher to fire in last_activity + 60, which is	1830	// the watcher to fire in last_activity + 60, which is
1402	// guaranteed to be in the future, so "again" is positive:	1831	// guaranteed to be in the future, so "again" is positive:
1403	w->again = timeout - now;	1832	w->repeat = timeout - now;
1404	ev_timer_again (EV_A_ w);	1833	ev_timer_again (EV_A_ w);
1405	}	1834	}
1406	}	1835	}
1407		1836
1408	To summarise the callback: first calculate the real timeout (defined	1837	To summarise the callback: first calculate the real timeout (defined
…		…
1421		1850
1422	To start the timer, simply initialise the watcher and set C<last_activity>	1851	To start the timer, simply initialise the watcher and set C<last_activity>
1423	to the current time (meaning we just have some activity :), then call the	1852	to the current time (meaning we just have some activity :), then call the
1424	callback, which will "do the right thing" and start the timer:	1853	callback, which will "do the right thing" and start the timer:
1425		1854
1426	ev_timer_init (timer, callback);	1855	ev_init (timer, callback);
1427	last_activity = ev_now (loop);	1856	last_activity = ev_now (loop);
1428	callback (loop, timer, EV_TIMEOUT);	1857	callback (loop, timer, EV_TIMER);
1429		1858
1430	And when there is some activity, simply store the current time in	1859	And when there is some activity, simply store the current time in
1431	C<last_activity>, no libev calls at all:	1860	C<last_activity>, no libev calls at all:
1432		1861
1433	last_actiivty = ev_now (loop);	1862	last_activity = ev_now (loop);
1434		1863
1435	This technique is slightly more complex, but in most cases where the	1864	This technique is slightly more complex, but in most cases where the
1436	time-out is unlikely to be triggered, much more efficient.	1865	time-out is unlikely to be triggered, much more efficient.
1437		1866
1438	Changing the timeout is trivial as well (if it isn't hard-coded in the	1867	Changing the timeout is trivial as well (if it isn't hard-coded in the
…		…
1476		1905
1477	=head3 The special problem of time updates	1906	=head3 The special problem of time updates
1478		1907
1479	Establishing the current time is a costly operation (it usually takes at	1908	Establishing the current time is a costly operation (it usually takes at
1480	least two system calls): EV therefore updates its idea of the current	1909	least two system calls): EV therefore updates its idea of the current
1481	time only before and after C<ev_loop> collects new events, which causes a	1910	time only before and after C<ev_run> collects new events, which causes a
1482	growing difference between C<ev_now ()> and C<ev_time ()> when handling	1911	growing difference between C<ev_now ()> and C<ev_time ()> when handling
1483	lots of events in one iteration.	1912	lots of events in one iteration.
1484		1913
1485	The relative timeouts are calculated relative to the C<ev_now ()>	1914	The relative timeouts are calculated relative to the C<ev_now ()>
1486	time. This is usually the right thing as this timestamp refers to the time	1915	time. This is usually the right thing as this timestamp refers to the time
…		…
1492		1921
1493	If the event loop is suspended for a long time, you can also force an	1922	If the event loop is suspended for a long time, you can also force an
1494	update of the time returned by C<ev_now ()> by calling C<ev_now_update	1923	update of the time returned by C<ev_now ()> by calling C<ev_now_update
1495	()>.	1924	()>.
1496		1925
		1926	=head3 The special problems of suspended animation
		1927
		1928	When you leave the server world it is quite customary to hit machines that
		1929	can suspend/hibernate - what happens to the clocks during such a suspend?
		1930
		1931	Some quick tests made with a Linux 2.6.28 indicate that a suspend freezes
		1932	all processes, while the clocks (C<times>, C<CLOCK_MONOTONIC>) continue
		1933	to run until the system is suspended, but they will not advance while the
		1934	system is suspended. That means, on resume, it will be as if the program
		1935	was frozen for a few seconds, but the suspend time will not be counted
		1936	towards C<ev_timer> when a monotonic clock source is used. The real time
		1937	clock advanced as expected, but if it is used as sole clocksource, then a
		1938	long suspend would be detected as a time jump by libev, and timers would
		1939	be adjusted accordingly.
		1940
		1941	I would not be surprised to see different behaviour in different between
		1942	operating systems, OS versions or even different hardware.
		1943
		1944	The other form of suspend (job control, or sending a SIGSTOP) will see a
		1945	time jump in the monotonic clocks and the realtime clock. If the program
		1946	is suspended for a very long time, and monotonic clock sources are in use,
		1947	then you can expect C<ev_timer>s to expire as the full suspension time
		1948	will be counted towards the timers. When no monotonic clock source is in
		1949	use, then libev will again assume a timejump and adjust accordingly.
		1950
		1951	It might be beneficial for this latter case to call C<ev_suspend>
		1952	and C<ev_resume> in code that handles C<SIGTSTP>, to at least get
		1953	deterministic behaviour in this case (you can do nothing against
		1954	C<SIGSTOP>).
		1955
1497	=head3 Watcher-Specific Functions and Data Members	1956	=head3 Watcher-Specific Functions and Data Members
1498		1957
1499	=over 4	1958	=over 4
1500		1959
1501	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	1960	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
…		…
1524	If the timer is started but non-repeating, stop it (as if it timed out).	1983	If the timer is started but non-repeating, stop it (as if it timed out).
1525		1984
1526	If the timer is repeating, either start it if necessary (with the	1985	If the timer is repeating, either start it if necessary (with the
1527	C<repeat> value), or reset the running timer to the C<repeat> value.	1986	C<repeat> value), or reset the running timer to the C<repeat> value.
1528		1987
1529	This sounds a bit complicated, see "Be smart about timeouts", above, for a	1988	This sounds a bit complicated, see L<Be smart about timeouts>, above, for a
1530	usage example.	1989	usage example.
		1990
		1991	=item ev_tstamp ev_timer_remaining (loop, ev_timer *)
		1992
		1993	Returns the remaining time until a timer fires. If the timer is active,
		1994	then this time is relative to the current event loop time, otherwise it's
		1995	the timeout value currently configured.
		1996
		1997	That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns
		1998	C<5>. When the timer is started and one second passes, C<ev_timer_remaining>
		1999	will return C<4>. When the timer expires and is restarted, it will return
		2000	roughly C<7> (likely slightly less as callback invocation takes some time,
		2001	too), and so on.
1531		2002
1532	=item ev_tstamp repeat [read-write]	2003	=item ev_tstamp repeat [read-write]
1533		2004
1534	The current C<repeat> value. Will be used each time the watcher times out	2005	The current C<repeat> value. Will be used each time the watcher times out
1535	or C<ev_timer_again> is called, and determines the next timeout (if any),	2006	or C<ev_timer_again> is called, and determines the next timeout (if any),
…		…
1561	}	2032	}
1562		2033
1563	ev_timer mytimer;	2034	ev_timer mytimer;
1564	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	2035	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1565	ev_timer_again (&mytimer); /* start timer */	2036	ev_timer_again (&mytimer); /* start timer */
1566	ev_loop (loop, 0);	2037	ev_run (loop, 0);
1567		2038
1568	// and in some piece of code that gets executed on any "activity":	2039	// and in some piece of code that gets executed on any "activity":
1569	// reset the timeout to start ticking again at 10 seconds	2040	// reset the timeout to start ticking again at 10 seconds
1570	ev_timer_again (&mytimer);	2041	ev_timer_again (&mytimer);
1571		2042
…		…
1573	=head2 C<ev_periodic> - to cron or not to cron?	2044	=head2 C<ev_periodic> - to cron or not to cron?
1574		2045
1575	Periodic watchers are also timers of a kind, but they are very versatile	2046	Periodic watchers are also timers of a kind, but they are very versatile
1576	(and unfortunately a bit complex).	2047	(and unfortunately a bit complex).
1577		2048
1578	Unlike C<ev_timer>'s, they are not based on real time (or relative time)	2049	Unlike C<ev_timer>, periodic watchers are not based on real time (or
1579	but on wall clock time (absolute time). You can tell a periodic watcher	2050	relative time, the physical time that passes) but on wall clock time
1580	to trigger after some specific point in time. For example, if you tell a	2051	(absolute time, the thing you can read on your calender or clock). The
1581	periodic watcher to trigger in 10 seconds (by specifying e.g. C<ev_now ()	2052	difference is that wall clock time can run faster or slower than real
1582	+ 10.>, that is, an absolute time not a delay) and then reset your system	2053	time, and time jumps are not uncommon (e.g. when you adjust your
1583	clock to January of the previous year, then it will take more than year	2054	wrist-watch).
1584	to trigger the event (unlike an C<ev_timer>, which would still trigger
1585	roughly 10 seconds later as it uses a relative timeout).
1586		2055
		2056	You can tell a periodic watcher to trigger after some specific point
		2057	in time: for example, if you tell a periodic watcher to trigger "in 10
		2058	seconds" (by specifying e.g. C<ev_now () + 10.>, that is, an absolute time
		2059	not a delay) and then reset your system clock to January of the previous
		2060	year, then it will take a year or more to trigger the event (unlike an
		2061	C<ev_timer>, which would still trigger roughly 10 seconds after starting
		2062	it, as it uses a relative timeout).
		2063
1587	C<ev_periodic>s can also be used to implement vastly more complex timers,	2064	C<ev_periodic> watchers can also be used to implement vastly more complex
1588	such as triggering an event on each "midnight, local time", or other	2065	timers, such as triggering an event on each "midnight, local time", or
1589	complicated rules.	2066	other complicated rules. This cannot be done with C<ev_timer> watchers, as
		2067	those cannot react to time jumps.
1590		2068
1591	As with timers, the callback is guaranteed to be invoked only when the	2069	As with timers, the callback is guaranteed to be invoked only when the
1592	time (C<at>) has passed, but if multiple periodic timers become ready	2070	point in time where it is supposed to trigger has passed. If multiple
1593	during the same loop iteration, then order of execution is undefined.	2071	timers become ready during the same loop iteration then the ones with
		2072	earlier time-out values are invoked before ones with later time-out values
		2073	(but this is no longer true when a callback calls C<ev_run> recursively).
1594		2074
1595	=head3 Watcher-Specific Functions and Data Members	2075	=head3 Watcher-Specific Functions and Data Members
1596		2076
1597	=over 4	2077	=over 4
1598		2078
1599	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)	2079	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp offset, ev_tstamp interval, reschedule_cb)
1600		2080
1601	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)	2081	=item ev_periodic_set (ev_periodic *, ev_tstamp offset, ev_tstamp interval, reschedule_cb)
1602		2082
1603	Lots of arguments, lets sort it out... There are basically three modes of	2083	Lots of arguments, let's sort it out... There are basically three modes of
1604	operation, and we will explain them from simplest to most complex:	2084	operation, and we will explain them from simplest to most complex:
1605		2085
1606	=over 4	2086	=over 4
1607		2087
1608	=item * absolute timer (at = time, interval = reschedule_cb = 0)	2088	=item * absolute timer (offset = absolute time, interval = 0, reschedule_cb = 0)
1609		2089
1610	In this configuration the watcher triggers an event after the wall clock	2090	In this configuration the watcher triggers an event after the wall clock
1611	time C<at> has passed. It will not repeat and will not adjust when a time	2091	time C<offset> has passed. It will not repeat and will not adjust when a
1612	jump occurs, that is, if it is to be run at January 1st 2011 then it will	2092	time jump occurs, that is, if it is to be run at January 1st 2011 then it
1613	only run when the system clock reaches or surpasses this time.	2093	will be stopped and invoked when the system clock reaches or surpasses
		2094	this point in time.
1614		2095
1615	=item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)	2096	=item * repeating interval timer (offset = offset within interval, interval > 0, reschedule_cb = 0)
1616		2097
1617	In this mode the watcher will always be scheduled to time out at the next	2098	In this mode the watcher will always be scheduled to time out at the next
1618	C<at + N * interval> time (for some integer N, which can also be negative)	2099	C<offset + N * interval> time (for some integer N, which can also be
1619	and then repeat, regardless of any time jumps.	2100	negative) and then repeat, regardless of any time jumps. The C<offset>
		2101	argument is merely an offset into the C<interval> periods.
1620		2102
1621	This can be used to create timers that do not drift with respect to the	2103	This can be used to create timers that do not drift with respect to the
1622	system clock, for example, here is a C<ev_periodic> that triggers each	2104	system clock, for example, here is an C<ev_periodic> that triggers each
1623	hour, on the hour:	2105	hour, on the hour (with respect to UTC):
1624		2106
1625	ev_periodic_set (&periodic, 0., 3600., 0);	2107	ev_periodic_set (&periodic, 0., 3600., 0);
1626		2108
1627	This doesn't mean there will always be 3600 seconds in between triggers,	2109	This doesn't mean there will always be 3600 seconds in between triggers,
1628	but only that the callback will be called when the system time shows a	2110	but only that the callback will be called when the system time shows a
1629	full hour (UTC), or more correctly, when the system time is evenly divisible	2111	full hour (UTC), or more correctly, when the system time is evenly divisible
1630	by 3600.	2112	by 3600.
1631		2113
1632	Another way to think about it (for the mathematically inclined) is that	2114	Another way to think about it (for the mathematically inclined) is that
1633	C<ev_periodic> will try to run the callback in this mode at the next possible	2115	C<ev_periodic> will try to run the callback in this mode at the next possible
1634	time where C<time = at (mod interval)>, regardless of any time jumps.	2116	time where C<time = offset (mod interval)>, regardless of any time jumps.
1635		2117
1636	For numerical stability it is preferable that the C<at> value is near	2118	For numerical stability it is preferable that the C<offset> value is near
1637	C<ev_now ()> (the current time), but there is no range requirement for	2119	C<ev_now ()> (the current time), but there is no range requirement for
1638	this value, and in fact is often specified as zero.	2120	this value, and in fact is often specified as zero.
1639		2121
1640	Note also that there is an upper limit to how often a timer can fire (CPU	2122	Note also that there is an upper limit to how often a timer can fire (CPU
1641	speed for example), so if C<interval> is very small then timing stability	2123	speed for example), so if C<interval> is very small then timing stability
1642	will of course deteriorate. Libev itself tries to be exact to be about one	2124	will of course deteriorate. Libev itself tries to be exact to be about one
1643	millisecond (if the OS supports it and the machine is fast enough).	2125	millisecond (if the OS supports it and the machine is fast enough).
1644		2126
1645	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)	2127	=item * manual reschedule mode (offset ignored, interval ignored, reschedule_cb = callback)
1646		2128
1647	In this mode the values for C<interval> and C<at> are both being	2129	In this mode the values for C<interval> and C<offset> are both being
1648	ignored. Instead, each time the periodic watcher gets scheduled, the	2130	ignored. Instead, each time the periodic watcher gets scheduled, the
1649	reschedule callback will be called with the watcher as first, and the	2131	reschedule callback will be called with the watcher as first, and the
1650	current time as second argument.	2132	current time as second argument.
1651		2133
1652	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,	2134	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, ever,
1653	ever, or make ANY event loop modifications whatsoever>.	2135	or make ANY other event loop modifications whatsoever, unless explicitly
		2136	allowed by documentation here>.
1654		2137
1655	If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop	2138	If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop
1656	it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the	2139	it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the
1657	only event loop modification you are allowed to do).	2140	only event loop modification you are allowed to do).
1658		2141
…		…
1688	a different time than the last time it was called (e.g. in a crond like	2171	a different time than the last time it was called (e.g. in a crond like
1689	program when the crontabs have changed).	2172	program when the crontabs have changed).
1690		2173
1691	=item ev_tstamp ev_periodic_at (ev_periodic *)	2174	=item ev_tstamp ev_periodic_at (ev_periodic *)
1692		2175
1693	When active, returns the absolute time that the watcher is supposed to	2176	When active, returns the absolute time that the watcher is supposed
1694	trigger next.	2177	to trigger next. This is not the same as the C<offset> argument to
		2178	C<ev_periodic_set>, but indeed works even in interval and manual
		2179	rescheduling modes.
1695		2180
1696	=item ev_tstamp offset [read-write]	2181	=item ev_tstamp offset [read-write]
1697		2182
1698	When repeating, this contains the offset value, otherwise this is the	2183	When repeating, this contains the offset value, otherwise this is the
1699	absolute point in time (the C<at> value passed to C<ev_periodic_set>).	2184	absolute point in time (the C<offset> value passed to C<ev_periodic_set>,
		2185	although libev might modify this value for better numerical stability).
1700		2186
1701	Can be modified any time, but changes only take effect when the periodic	2187	Can be modified any time, but changes only take effect when the periodic
1702	timer fires or C<ev_periodic_again> is being called.	2188	timer fires or C<ev_periodic_again> is being called.
1703		2189
1704	=item ev_tstamp interval [read-write]	2190	=item ev_tstamp interval [read-write]
…		…
1720	Example: Call a callback every hour, or, more precisely, whenever the	2206	Example: Call a callback every hour, or, more precisely, whenever the
1721	system time is divisible by 3600. The callback invocation times have	2207	system time is divisible by 3600. The callback invocation times have
1722	potentially a lot of jitter, but good long-term stability.	2208	potentially a lot of jitter, but good long-term stability.
1723		2209
1724	static void	2210	static void
1725	clock_cb (struct ev_loop *loop, ev_io *w, int revents)	2211	clock_cb (struct ev_loop *loop, ev_periodic *w, int revents)
1726	{	2212	{
1727	... its now a full hour (UTC, or TAI or whatever your clock follows)	2213	... its now a full hour (UTC, or TAI or whatever your clock follows)
1728	}	2214	}
1729		2215
1730	ev_periodic hourly_tick;	2216	ev_periodic hourly_tick;
…		…
1756	Signal watchers will trigger an event when the process receives a specific	2242	Signal watchers will trigger an event when the process receives a specific
1757	signal one or more times. Even though signals are very asynchronous, libev	2243	signal one or more times. Even though signals are very asynchronous, libev
1758	will try it's best to deliver signals synchronously, i.e. as part of the	2244	will try it's best to deliver signals synchronously, i.e. as part of the
1759	normal event processing, like any other event.	2245	normal event processing, like any other event.
1760		2246
1761	If you want signals asynchronously, just use C<sigaction> as you would	2247	If you want signals to be delivered truly asynchronously, just use
1762	do without libev and forget about sharing the signal. You can even use	2248	C<sigaction> as you would do without libev and forget about sharing
1763	C<ev_async> from a signal handler to synchronously wake up an event loop.	2249	the signal. You can even use C<ev_async> from a signal handler to
		2250	synchronously wake up an event loop.
1764		2251
1765	You can configure as many watchers as you like per signal. Only when the	2252	You can configure as many watchers as you like for the same signal, but
		2253	only within the same loop, i.e. you can watch for C<SIGINT> in your
		2254	default loop and for C<SIGIO> in another loop, but you cannot watch for
		2255	C<SIGINT> in both the default loop and another loop at the same time. At
		2256	the moment, C<SIGCHLD> is permanently tied to the default loop.
		2257
1766	first watcher gets started will libev actually register a signal handler	2258	When the first watcher gets started will libev actually register something
1767	with the kernel (thus it coexists with your own signal handlers as long as	2259	with the kernel (thus it coexists with your own signal handlers as long as
1768	you don't register any with libev for the same signal). Similarly, when	2260	you don't register any with libev for the same signal).
1769	the last signal watcher for a signal is stopped, libev will reset the
1770	signal handler to SIG_DFL (regardless of what it was set to before).
1771		2261
1772	If possible and supported, libev will install its handlers with	2262	If possible and supported, libev will install its handlers with
1773	C<SA_RESTART> behaviour enabled, so system calls should not be unduly	2263	C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should
1774	interrupted. If you have a problem with system calls getting interrupted by	2264	not be unduly interrupted. If you have a problem with system calls getting
1775	signals you can block all signals in an C<ev_check> watcher and unblock	2265	interrupted by signals you can block all signals in an C<ev_check> watcher
1776	them in an C<ev_prepare> watcher.	2266	and unblock them in an C<ev_prepare> watcher.
		2267
		2268	=head3 The special problem of inheritance over fork/execve/pthread_create
		2269
		2270	Both the signal mask (C<sigprocmask>) and the signal disposition
		2271	(C<sigaction>) are unspecified after starting a signal watcher (and after
		2272	stopping it again), that is, libev might or might not block the signal,
		2273	and might or might not set or restore the installed signal handler.
		2274
		2275	While this does not matter for the signal disposition (libev never
		2276	sets signals to C<SIG_IGN>, so handlers will be reset to C<SIG_DFL> on
		2277	C<execve>), this matters for the signal mask: many programs do not expect
		2278	certain signals to be blocked.
		2279
		2280	This means that before calling C<exec> (from the child) you should reset
		2281	the signal mask to whatever "default" you expect (all clear is a good
		2282	choice usually).
		2283
		2284	The simplest way to ensure that the signal mask is reset in the child is
		2285	to install a fork handler with C<pthread_atfork> that resets it. That will
		2286	catch fork calls done by libraries (such as the libc) as well.
		2287
		2288	In current versions of libev, the signal will not be blocked indefinitely
		2289	unless you use the C<signalfd> API (C<EV_SIGNALFD>). While this reduces
		2290	the window of opportunity for problems, it will not go away, as libev
		2291	I<has> to modify the signal mask, at least temporarily.
		2292
		2293	So I can't stress this enough: I<If you do not reset your signal mask when
		2294	you expect it to be empty, you have a race condition in your code>. This
		2295	is not a libev-specific thing, this is true for most event libraries.
1777		2296
1778	=head3 Watcher-Specific Functions and Data Members	2297	=head3 Watcher-Specific Functions and Data Members
1779		2298
1780	=over 4	2299	=over 4
1781		2300
…		…
1797	Example: Try to exit cleanly on SIGINT.	2316	Example: Try to exit cleanly on SIGINT.
1798		2317
1799	static void	2318	static void
1800	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)	2319	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)
1801	{	2320	{
1802	ev_unloop (loop, EVUNLOOP_ALL);	2321	ev_break (loop, EVBREAK_ALL);
1803	}	2322	}
1804		2323
1805	ev_signal signal_watcher;	2324	ev_signal signal_watcher;
1806	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	2325	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1807	ev_signal_start (loop, &signal_watcher);	2326	ev_signal_start (loop, &signal_watcher);
…		…
1813	some child status changes (most typically when a child of yours dies or	2332	some child status changes (most typically when a child of yours dies or
1814	exits). It is permissible to install a child watcher I<after> the child	2333	exits). It is permissible to install a child watcher I<after> the child
1815	has been forked (which implies it might have already exited), as long	2334	has been forked (which implies it might have already exited), as long
1816	as the event loop isn't entered (or is continued from a watcher), i.e.,	2335	as the event loop isn't entered (or is continued from a watcher), i.e.,
1817	forking and then immediately registering a watcher for the child is fine,	2336	forking and then immediately registering a watcher for the child is fine,
1818	but forking and registering a watcher a few event loop iterations later is	2337	but forking and registering a watcher a few event loop iterations later or
1819	not.	2338	in the next callback invocation is not.
1820		2339
1821	Only the default event loop is capable of handling signals, and therefore	2340	Only the default event loop is capable of handling signals, and therefore
1822	you can only register child watchers in the default event loop.	2341	you can only register child watchers in the default event loop.
1823		2342
		2343	Due to some design glitches inside libev, child watchers will always be
		2344	handled at maximum priority (their priority is set to C<EV_MAXPRI> by
		2345	libev)
		2346
1824	=head3 Process Interaction	2347	=head3 Process Interaction
1825		2348
1826	Libev grabs C<SIGCHLD> as soon as the default event loop is	2349	Libev grabs C<SIGCHLD> as soon as the default event loop is
1827	initialised. This is necessary to guarantee proper behaviour even if	2350	initialised. This is necessary to guarantee proper behaviour even if the
1828	the first child watcher is started after the child exits. The occurrence	2351	first child watcher is started after the child exits. The occurrence
1829	of C<SIGCHLD> is recorded asynchronously, but child reaping is done	2352	of C<SIGCHLD> is recorded asynchronously, but child reaping is done
1830	synchronously as part of the event loop processing. Libev always reaps all	2353	synchronously as part of the event loop processing. Libev always reaps all
1831	children, even ones not watched.	2354	children, even ones not watched.
1832		2355
1833	=head3 Overriding the Built-In Processing	2356	=head3 Overriding the Built-In Processing
…		…
1843	=head3 Stopping the Child Watcher	2366	=head3 Stopping the Child Watcher
1844		2367
1845	Currently, the child watcher never gets stopped, even when the	2368	Currently, the child watcher never gets stopped, even when the
1846	child terminates, so normally one needs to stop the watcher in the	2369	child terminates, so normally one needs to stop the watcher in the
1847	callback. Future versions of libev might stop the watcher automatically	2370	callback. Future versions of libev might stop the watcher automatically
1848	when a child exit is detected.	2371	when a child exit is detected (calling C<ev_child_stop> twice is not a
		2372	problem).
1849		2373
1850	=head3 Watcher-Specific Functions and Data Members	2374	=head3 Watcher-Specific Functions and Data Members
1851		2375
1852	=over 4	2376	=over 4
1853		2377
…		…
1910		2434
1911		2435
1912	=head2 C<ev_stat> - did the file attributes just change?	2436	=head2 C<ev_stat> - did the file attributes just change?
1913		2437
1914	This watches a file system path for attribute changes. That is, it calls	2438	This watches a file system path for attribute changes. That is, it calls
1915	C<stat> regularly (or when the OS says it changed) and sees if it changed	2439	C<stat> on that path in regular intervals (or when the OS says it changed)
1916	compared to the last time, invoking the callback if it did.	2440	and sees if it changed compared to the last time, invoking the callback if
		2441	it did.
1917		2442
1918	The path does not need to exist: changing from "path exists" to "path does	2443	The path does not need to exist: changing from "path exists" to "path does
1919	not exist" is a status change like any other. The condition "path does	2444	not exist" is a status change like any other. The condition "path does not
1920	not exist" is signified by the C<st_nlink> field being zero (which is	2445	exist" (or more correctly "path cannot be stat'ed") is signified by the
1921	otherwise always forced to be at least one) and all the other fields of	2446	C<st_nlink> field being zero (which is otherwise always forced to be at
1922	the stat buffer having unspecified contents.	2447	least one) and all the other fields of the stat buffer having unspecified
		2448	contents.
1923		2449
1924	The path I<should> be absolute and I<must not> end in a slash. If it is	2450	The path I<must not> end in a slash or contain special components such as
		2451	C<.> or C<..>. The path I<should> be absolute: If it is relative and
1925	relative and your working directory changes, the behaviour is undefined.	2452	your working directory changes, then the behaviour is undefined.
1926		2453
1927	Since there is no standard kernel interface to do this, the portable	2454	Since there is no portable change notification interface available, the
1928	implementation simply calls C<stat (2)> regularly on the path to see if	2455	portable implementation simply calls C<stat(2)> regularly on the path
1929	it changed somehow. You can specify a recommended polling interval for	2456	to see if it changed somehow. You can specify a recommended polling
1930	this case. If you specify a polling interval of C<0> (highly recommended!)	2457	interval for this case. If you specify a polling interval of C<0> (highly
1931	then a I<suitable, unspecified default> value will be used (which	2458	recommended!) then a I<suitable, unspecified default> value will be used
1932	you can expect to be around five seconds, although this might change	2459	(which you can expect to be around five seconds, although this might
1933	dynamically). Libev will also impose a minimum interval which is currently	2460	change dynamically). Libev will also impose a minimum interval which is
1934	around C<0.1>, but thats usually overkill.	2461	currently around C<0.1>, but that's usually overkill.
1935		2462
1936	This watcher type is not meant for massive numbers of stat watchers,	2463	This watcher type is not meant for massive numbers of stat watchers,
1937	as even with OS-supported change notifications, this can be	2464	as even with OS-supported change notifications, this can be
1938	resource-intensive.	2465	resource-intensive.
1939		2466
1940	At the time of this writing, the only OS-specific interface implemented	2467	At the time of this writing, the only OS-specific interface implemented
1941	is the Linux inotify interface (implementing kqueue support is left as	2468	is the Linux inotify interface (implementing kqueue support is left as an
1942	an exercise for the reader. Note, however, that the author sees no way	2469	exercise for the reader. Note, however, that the author sees no way of
1943	of implementing C<ev_stat> semantics with kqueue).	2470	implementing C<ev_stat> semantics with kqueue, except as a hint).
1944		2471
1945	=head3 ABI Issues (Largefile Support)	2472	=head3 ABI Issues (Largefile Support)
1946		2473
1947	Libev by default (unless the user overrides this) uses the default	2474	Libev by default (unless the user overrides this) uses the default
1948	compilation environment, which means that on systems with large file	2475	compilation environment, which means that on systems with large file
1949	support disabled by default, you get the 32 bit version of the stat	2476	support disabled by default, you get the 32 bit version of the stat
1950	structure. When using the library from programs that change the ABI to	2477	structure. When using the library from programs that change the ABI to
1951	use 64 bit file offsets the programs will fail. In that case you have to	2478	use 64 bit file offsets the programs will fail. In that case you have to
1952	compile libev with the same flags to get binary compatibility. This is	2479	compile libev with the same flags to get binary compatibility. This is
1953	obviously the case with any flags that change the ABI, but the problem is	2480	obviously the case with any flags that change the ABI, but the problem is
1954	most noticeably disabled with ev_stat and large file support.	2481	most noticeably displayed with ev_stat and large file support.
1955		2482
1956	The solution for this is to lobby your distribution maker to make large	2483	The solution for this is to lobby your distribution maker to make large
1957	file interfaces available by default (as e.g. FreeBSD does) and not	2484	file interfaces available by default (as e.g. FreeBSD does) and not
1958	optional. Libev cannot simply switch on large file support because it has	2485	optional. Libev cannot simply switch on large file support because it has
1959	to exchange stat structures with application programs compiled using the	2486	to exchange stat structures with application programs compiled using the
1960	default compilation environment.	2487	default compilation environment.
1961		2488
1962	=head3 Inotify and Kqueue	2489	=head3 Inotify and Kqueue
1963		2490
1964	When C<inotify (7)> support has been compiled into libev (generally	2491	When C<inotify (7)> support has been compiled into libev and present at
1965	only available with Linux 2.6.25 or above due to bugs in earlier	2492	runtime, it will be used to speed up change detection where possible. The
1966	implementations) and present at runtime, it will be used to speed up	2493	inotify descriptor will be created lazily when the first C<ev_stat>
1967	change detection where possible. The inotify descriptor will be created	2494	watcher is being started.
1968	lazily when the first C<ev_stat> watcher is being started.
1969		2495
1970	Inotify presence does not change the semantics of C<ev_stat> watchers	2496	Inotify presence does not change the semantics of C<ev_stat> watchers
1971	except that changes might be detected earlier, and in some cases, to avoid	2497	except that changes might be detected earlier, and in some cases, to avoid
1972	making regular C<stat> calls. Even in the presence of inotify support	2498	making regular C<stat> calls. Even in the presence of inotify support
1973	there are many cases where libev has to resort to regular C<stat> polling,	2499	there are many cases where libev has to resort to regular C<stat> polling,
1974	but as long as the path exists, libev usually gets away without polling.	2500	but as long as kernel 2.6.25 or newer is used (2.6.24 and older have too
		2501	many bugs), the path exists (i.e. stat succeeds), and the path resides on
		2502	a local filesystem (libev currently assumes only ext2/3, jfs, reiserfs and
		2503	xfs are fully working) libev usually gets away without polling.
1975		2504
1976	There is no support for kqueue, as apparently it cannot be used to	2505	There is no support for kqueue, as apparently it cannot be used to
1977	implement this functionality, due to the requirement of having a file	2506	implement this functionality, due to the requirement of having a file
1978	descriptor open on the object at all times, and detecting renames, unlinks	2507	descriptor open on the object at all times, and detecting renames, unlinks
1979	etc. is difficult.	2508	etc. is difficult.
1980		2509
		2510	=head3 C<stat ()> is a synchronous operation
		2511
		2512	Libev doesn't normally do any kind of I/O itself, and so is not blocking
		2513	the process. The exception are C<ev_stat> watchers - those call C<stat
		2514	()>, which is a synchronous operation.
		2515
		2516	For local paths, this usually doesn't matter: unless the system is very
		2517	busy or the intervals between stat's are large, a stat call will be fast,
		2518	as the path data is usually in memory already (except when starting the
		2519	watcher).
		2520
		2521	For networked file systems, calling C<stat ()> can block an indefinite
		2522	time due to network issues, and even under good conditions, a stat call
		2523	often takes multiple milliseconds.
		2524
		2525	Therefore, it is best to avoid using C<ev_stat> watchers on networked
		2526	paths, although this is fully supported by libev.
		2527
1981	=head3 The special problem of stat time resolution	2528	=head3 The special problem of stat time resolution
1982		2529
1983	The C<stat ()> system call only supports full-second resolution portably, and	2530	The C<stat ()> system call only supports full-second resolution portably,
1984	even on systems where the resolution is higher, most file systems still	2531	and even on systems where the resolution is higher, most file systems
1985	only support whole seconds.	2532	still only support whole seconds.
1986		2533
1987	That means that, if the time is the only thing that changes, you can	2534	That means that, if the time is the only thing that changes, you can
1988	easily miss updates: on the first update, C<ev_stat> detects a change and	2535	easily miss updates: on the first update, C<ev_stat> detects a change and
1989	calls your callback, which does something. When there is another update	2536	calls your callback, which does something. When there is another update
1990	within the same second, C<ev_stat> will be unable to detect unless the	2537	within the same second, C<ev_stat> will be unable to detect unless the
…		…
2133		2680
2134	=head3 Watcher-Specific Functions and Data Members	2681	=head3 Watcher-Specific Functions and Data Members
2135		2682
2136	=over 4	2683	=over 4
2137		2684
2138	=item ev_idle_init (ev_signal *, callback)	2685	=item ev_idle_init (ev_idle *, callback)
2139		2686
2140	Initialises and configures the idle watcher - it has no parameters of any	2687	Initialises and configures the idle watcher - it has no parameters of any
2141	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,	2688	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,
2142	believe me.	2689	believe me.
2143		2690
…		…
2156	// no longer anything immediate to do.	2703	// no longer anything immediate to do.
2157	}	2704	}
2158		2705
2159	ev_idle *idle_watcher = malloc (sizeof (ev_idle));	2706	ev_idle *idle_watcher = malloc (sizeof (ev_idle));
2160	ev_idle_init (idle_watcher, idle_cb);	2707	ev_idle_init (idle_watcher, idle_cb);
2161	ev_idle_start (loop, idle_cb);	2708	ev_idle_start (loop, idle_watcher);
2162		2709
2163		2710
2164	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!	2711	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!
2165		2712
2166	Prepare and check watchers are usually (but not always) used in pairs:	2713	Prepare and check watchers are usually (but not always) used in pairs:
2167	prepare watchers get invoked before the process blocks and check watchers	2714	prepare watchers get invoked before the process blocks and check watchers
2168	afterwards.	2715	afterwards.
2169		2716
2170	You I<must not> call C<ev_loop> or similar functions that enter	2717	You I<must not> call C<ev_run> or similar functions that enter
2171	the current event loop from either C<ev_prepare> or C<ev_check>	2718	the current event loop from either C<ev_prepare> or C<ev_check>
2172	watchers. Other loops than the current one are fine, however. The	2719	watchers. Other loops than the current one are fine, however. The
2173	rationale behind this is that you do not need to check for recursion in	2720	rationale behind this is that you do not need to check for recursion in
2174	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,	2721	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,
2175	C<ev_check> so if you have one watcher of each kind they will always be	2722	C<ev_check> so if you have one watcher of each kind they will always be
…		…
2259	struct pollfd fds [nfd];	2806	struct pollfd fds [nfd];
2260	// actual code will need to loop here and realloc etc.	2807	// actual code will need to loop here and realloc etc.
2261	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	2808	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
2262		2809
2263	/* the callback is illegal, but won't be called as we stop during check */	2810	/* the callback is illegal, but won't be called as we stop during check */
2264	ev_timer_init (&tw, 0, timeout * 1e-3);	2811	ev_timer_init (&tw, 0, timeout * 1e-3, 0.);
2265	ev_timer_start (loop, &tw);	2812	ev_timer_start (loop, &tw);
2266		2813
2267	// create one ev_io per pollfd	2814	// create one ev_io per pollfd
2268	for (int i = 0; i < nfd; ++i)	2815	for (int i = 0; i < nfd; ++i)
2269	{	2816	{
…		…
2343		2890
2344	if (timeout >= 0)	2891	if (timeout >= 0)
2345	// create/start timer	2892	// create/start timer
2346		2893
2347	// poll	2894	// poll
2348	ev_loop (EV_A_ 0);	2895	ev_run (EV_A_ 0);
2349		2896
2350	// stop timer again	2897	// stop timer again
2351	if (timeout >= 0)	2898	if (timeout >= 0)
2352	ev_timer_stop (EV_A_ &to);	2899	ev_timer_stop (EV_A_ &to);
2353		2900
…		…
2382	some fds have to be watched and handled very quickly (with low latency),	2929	some fds have to be watched and handled very quickly (with low latency),
2383	and even priorities and idle watchers might have too much overhead. In	2930	and even priorities and idle watchers might have too much overhead. In
2384	this case you would put all the high priority stuff in one loop and all	2931	this case you would put all the high priority stuff in one loop and all
2385	the rest in a second one, and embed the second one in the first.	2932	the rest in a second one, and embed the second one in the first.
2386		2933
2387	As long as the watcher is active, the callback will be invoked every time	2934	As long as the watcher is active, the callback will be invoked every
2388	there might be events pending in the embedded loop. The callback must then	2935	time there might be events pending in the embedded loop. The callback
2389	call C<ev_embed_sweep (mainloop, watcher)> to make a single sweep and invoke	2936	must then call C<ev_embed_sweep (mainloop, watcher)> to make a single
2390	their callbacks (you could also start an idle watcher to give the embedded	2937	sweep and invoke their callbacks (the callback doesn't need to invoke the
2391	loop strictly lower priority for example). You can also set the callback	2938	C<ev_embed_sweep> function directly, it could also start an idle watcher
2392	to C<0>, in which case the embed watcher will automatically execute the	2939	to give the embedded loop strictly lower priority for example).
2393	embedded loop sweep.
2394		2940
2395	As long as the watcher is started it will automatically handle events. The	2941	You can also set the callback to C<0>, in which case the embed watcher
2396	callback will be invoked whenever some events have been handled. You can	2942	will automatically execute the embedded loop sweep whenever necessary.
2397	set the callback to C<0> to avoid having to specify one if you are not
2398	interested in that.
2399		2943
2400	Also, there have not currently been made special provisions for forking:	2944	Fork detection will be handled transparently while the C<ev_embed> watcher
2401	when you fork, you not only have to call C<ev_loop_fork> on both loops,	2945	is active, i.e., the embedded loop will automatically be forked when the
2402	but you will also have to stop and restart any C<ev_embed> watchers	2946	embedding loop forks. In other cases, the user is responsible for calling
2403	yourself - but you can use a fork watcher to handle this automatically,	2947	C<ev_loop_fork> on the embedded loop.
2404	and future versions of libev might do just that.
2405		2948
2406	Unfortunately, not all backends are embeddable: only the ones returned by	2949	Unfortunately, not all backends are embeddable: only the ones returned by
2407	C<ev_embeddable_backends> are, which, unfortunately, does not include any	2950	C<ev_embeddable_backends> are, which, unfortunately, does not include any
2408	portable one.	2951	portable one.
2409		2952
…		…
2435	if you do not want that, you need to temporarily stop the embed watcher).	2978	if you do not want that, you need to temporarily stop the embed watcher).
2436		2979
2437	=item ev_embed_sweep (loop, ev_embed *)	2980	=item ev_embed_sweep (loop, ev_embed *)
2438		2981
2439	Make a single, non-blocking sweep over the embedded loop. This works	2982	Make a single, non-blocking sweep over the embedded loop. This works
2440	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	2983	similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most
2441	appropriate way for embedded loops.	2984	appropriate way for embedded loops.
2442		2985
2443	=item struct ev_loop *other [read-only]	2986	=item struct ev_loop *other [read-only]
2444		2987
2445	The embedded event loop.	2988	The embedded event loop.
…		…
2503	event loop blocks next and before C<ev_check> watchers are being called,	3046	event loop blocks next and before C<ev_check> watchers are being called,
2504	and only in the child after the fork. If whoever good citizen calling	3047	and only in the child after the fork. If whoever good citizen calling
2505	C<ev_default_fork> cheats and calls it in the wrong process, the fork	3048	C<ev_default_fork> cheats and calls it in the wrong process, the fork
2506	handlers will be invoked, too, of course.	3049	handlers will be invoked, too, of course.
2507		3050
		3051	=head3 The special problem of life after fork - how is it possible?
		3052
		3053	Most uses of C<fork()> consist of forking, then some simple calls to set
		3054	up/change the process environment, followed by a call to C<exec()>. This
		3055	sequence should be handled by libev without any problems.
		3056
		3057	This changes when the application actually wants to do event handling
		3058	in the child, or both parent in child, in effect "continuing" after the
		3059	fork.
		3060
		3061	The default mode of operation (for libev, with application help to detect
		3062	forks) is to duplicate all the state in the child, as would be expected
		3063	when I<either> the parent I<or> the child process continues.
		3064
		3065	When both processes want to continue using libev, then this is usually the
		3066	wrong result. In that case, usually one process (typically the parent) is
		3067	supposed to continue with all watchers in place as before, while the other
		3068	process typically wants to start fresh, i.e. without any active watchers.
		3069
		3070	The cleanest and most efficient way to achieve that with libev is to
		3071	simply create a new event loop, which of course will be "empty", and
		3072	use that for new watchers. This has the advantage of not touching more
		3073	memory than necessary, and thus avoiding the copy-on-write, and the
		3074	disadvantage of having to use multiple event loops (which do not support
		3075	signal watchers).
		3076
		3077	When this is not possible, or you want to use the default loop for
		3078	other reasons, then in the process that wants to start "fresh", call
		3079	C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying
		3080	the default loop will "orphan" (not stop) all registered watchers, so you
		3081	have to be careful not to execute code that modifies those watchers. Note
		3082	also that in that case, you have to re-register any signal watchers.
		3083
2508	=head3 Watcher-Specific Functions and Data Members	3084	=head3 Watcher-Specific Functions and Data Members
2509		3085
2510	=over 4	3086	=over 4
2511		3087
2512	=item ev_fork_init (ev_signal *, callback)	3088	=item ev_fork_init (ev_signal *, callback)
…		…
2516	believe me.	3092	believe me.
2517		3093
2518	=back	3094	=back
2519		3095
2520		3096
2521	=head2 C<ev_async> - how to wake up another event loop	3097	=head2 C<ev_async> - how to wake up an event loop
2522		3098
2523	In general, you cannot use an C<ev_loop> from multiple threads or other	3099	In general, you cannot use an C<ev_run> from multiple threads or other
2524	asynchronous sources such as signal handlers (as opposed to multiple event	3100	asynchronous sources such as signal handlers (as opposed to multiple event
2525	loops - those are of course safe to use in different threads).	3101	loops - those are of course safe to use in different threads).
2526		3102
2527	Sometimes, however, you need to wake up another event loop you do not	3103	Sometimes, however, you need to wake up an event loop you do not control,
2528	control, for example because it belongs to another thread. This is what	3104	for example because it belongs to another thread. This is what C<ev_async>
2529	C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you	3105	watchers do: as long as the C<ev_async> watcher is active, you can signal
2530	can signal it by calling C<ev_async_send>, which is thread- and signal	3106	it by calling C<ev_async_send>, which is thread- and signal safe.
2531	safe.
2532		3107
2533	This functionality is very similar to C<ev_signal> watchers, as signals,	3108	This functionality is very similar to C<ev_signal> watchers, as signals,
2534	too, are asynchronous in nature, and signals, too, will be compressed	3109	too, are asynchronous in nature, and signals, too, will be compressed
2535	(i.e. the number of callback invocations may be less than the number of	3110	(i.e. the number of callback invocations may be less than the number of
2536	C<ev_async_sent> calls).	3111	C<ev_async_sent> calls).
…		…
2541	=head3 Queueing	3116	=head3 Queueing
2542		3117
2543	C<ev_async> does not support queueing of data in any way. The reason	3118	C<ev_async> does not support queueing of data in any way. The reason
2544	is that the author does not know of a simple (or any) algorithm for a	3119	is that the author does not know of a simple (or any) algorithm for a
2545	multiple-writer-single-reader queue that works in all cases and doesn't	3120	multiple-writer-single-reader queue that works in all cases and doesn't
2546	need elaborate support such as pthreads.	3121	need elaborate support such as pthreads or unportable memory access
		3122	semantics.
2547		3123
2548	That means that if you want to queue data, you have to provide your own	3124	That means that if you want to queue data, you have to provide your own
2549	queue. But at least I can tell you how to implement locking around your	3125	queue. But at least I can tell you how to implement locking around your
2550	queue:	3126	queue:
2551		3127
…		…
2629	=over 4	3205	=over 4
2630		3206
2631	=item ev_async_init (ev_async *, callback)	3207	=item ev_async_init (ev_async *, callback)
2632		3208
2633	Initialises and configures the async watcher - it has no parameters of any	3209	Initialises and configures the async watcher - it has no parameters of any
2634	kind. There is a C<ev_asynd_set> macro, but using it is utterly pointless,	3210	kind. There is a C<ev_async_set> macro, but using it is utterly pointless,
2635	trust me.	3211	trust me.
2636		3212
2637	=item ev_async_send (loop, ev_async *)	3213	=item ev_async_send (loop, ev_async *)
2638		3214
2639	Sends/signals/activates the given C<ev_async> watcher, that is, feeds	3215	Sends/signals/activates the given C<ev_async> watcher, that is, feeds
2640	an C<EV_ASYNC> event on the watcher into the event loop. Unlike	3216	an C<EV_ASYNC> event on the watcher into the event loop. Unlike
2641	C<ev_feed_event>, this call is safe to do from other threads, signal or	3217	C<ev_feed_event>, this call is safe to do from other threads, signal or
2642	similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding	3218	similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding
2643	section below on what exactly this means).	3219	section below on what exactly this means).
2644		3220
		3221	Note that, as with other watchers in libev, multiple events might get
		3222	compressed into a single callback invocation (another way to look at this
		3223	is that C<ev_async> watchers are level-triggered, set on C<ev_async_send>,
		3224	reset when the event loop detects that).
		3225
2645	This call incurs the overhead of a system call only once per loop iteration,	3226	This call incurs the overhead of a system call only once per event loop
2646	so while the overhead might be noticeable, it doesn't apply to repeated	3227	iteration, so while the overhead might be noticeable, it doesn't apply to
2647	calls to C<ev_async_send>.	3228	repeated calls to C<ev_async_send> for the same event loop.
2648		3229
2649	=item bool = ev_async_pending (ev_async *)	3230	=item bool = ev_async_pending (ev_async *)
2650		3231
2651	Returns a non-zero value when C<ev_async_send> has been called on the	3232	Returns a non-zero value when C<ev_async_send> has been called on the
2652	watcher but the event has not yet been processed (or even noted) by the	3233	watcher but the event has not yet been processed (or even noted) by the
…		…
2655	C<ev_async_send> sets a flag in the watcher and wakes up the loop. When	3236	C<ev_async_send> sets a flag in the watcher and wakes up the loop. When
2656	the loop iterates next and checks for the watcher to have become active,	3237	the loop iterates next and checks for the watcher to have become active,
2657	it will reset the flag again. C<ev_async_pending> can be used to very	3238	it will reset the flag again. C<ev_async_pending> can be used to very
2658	quickly check whether invoking the loop might be a good idea.	3239	quickly check whether invoking the loop might be a good idea.
2659		3240
2660	Not that this does I<not> check whether the watcher itself is pending, only	3241	Not that this does I<not> check whether the watcher itself is pending,
2661	whether it has been requested to make this watcher pending.	3242	only whether it has been requested to make this watcher pending: there
		3243	is a time window between the event loop checking and resetting the async
		3244	notification, and the callback being invoked.
2662		3245
2663	=back	3246	=back
2664		3247
2665		3248
2666	=head1 OTHER FUNCTIONS	3249	=head1 OTHER FUNCTIONS
…		…
2683		3266
2684	If C<timeout> is less than 0, then no timeout watcher will be	3267	If C<timeout> is less than 0, then no timeout watcher will be
2685	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and	3268	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and
2686	repeat = 0) will be started. C<0> is a valid timeout.	3269	repeat = 0) will be started. C<0> is a valid timeout.
2687		3270
2688	The callback has the type C<void (*cb)(int revents, void *arg)> and gets	3271	The callback has the type C<void (*cb)(int revents, void *arg)> and is
2689	passed an C<revents> set like normal event callbacks (a combination of	3272	passed an C<revents> set like normal event callbacks (a combination of
2690	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>	3273	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMER>) and the C<arg>
2691	value passed to C<ev_once>. Note that it is possible to receive I<both>	3274	value passed to C<ev_once>. Note that it is possible to receive I<both>
2692	a timeout and an io event at the same time - you probably should give io	3275	a timeout and an io event at the same time - you probably should give io
2693	events precedence.	3276	events precedence.
2694		3277
2695	Example: wait up to ten seconds for data to appear on STDIN_FILENO.	3278	Example: wait up to ten seconds for data to appear on STDIN_FILENO.
2696		3279
2697	static void stdin_ready (int revents, void *arg)	3280	static void stdin_ready (int revents, void *arg)
2698	{	3281	{
2699	if (revents & EV_READ)	3282	if (revents & EV_READ)
2700	/* stdin might have data for us, joy! */;	3283	/* stdin might have data for us, joy! */;
2701	else if (revents & EV_TIMEOUT)	3284	else if (revents & EV_TIMER)
2702	/* doh, nothing entered */;	3285	/* doh, nothing entered */;
2703	}	3286	}
2704		3287
2705	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	3288	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
2706		3289
2707	=item ev_feed_event (struct ev_loop *, watcher *, int revents)
2708
2709	Feeds the given event set into the event loop, as if the specified event
2710	had happened for the specified watcher (which must be a pointer to an
2711	initialised but not necessarily started event watcher).
2712
2713	=item ev_feed_fd_event (struct ev_loop *, int fd, int revents)	3290	=item ev_feed_fd_event (loop, int fd, int revents)
2714		3291
2715	Feed an event on the given fd, as if a file descriptor backend detected	3292	Feed an event on the given fd, as if a file descriptor backend detected
2716	the given events it.	3293	the given events it.
2717		3294
2718	=item ev_feed_signal_event (struct ev_loop *loop, int signum)	3295	=item ev_feed_signal_event (loop, int signum)
2719		3296
2720	Feed an event as if the given signal occurred (C<loop> must be the default	3297	Feed an event as if the given signal occurred (C<loop> must be the default
2721	loop!).	3298	loop!).
2722		3299
2723	=back	3300	=back
…		…
2803		3380
2804	=over 4	3381	=over 4
2805		3382
2806	=item ev::TYPE::TYPE ()	3383	=item ev::TYPE::TYPE ()
2807		3384
2808	=item ev::TYPE::TYPE (struct ev_loop *)	3385	=item ev::TYPE::TYPE (loop)
2809		3386
2810	=item ev::TYPE::~TYPE	3387	=item ev::TYPE::~TYPE
2811		3388
2812	The constructor (optionally) takes an event loop to associate the watcher	3389	The constructor (optionally) takes an event loop to associate the watcher
2813	with. If it is omitted, it will use C<EV_DEFAULT>.	3390	with. If it is omitted, it will use C<EV_DEFAULT>.
…		…
2845		3422
2846	myclass obj;	3423	myclass obj;
2847	ev::io iow;	3424	ev::io iow;
2848	iow.set <myclass, &myclass::io_cb> (&obj);	3425	iow.set <myclass, &myclass::io_cb> (&obj);
2849		3426
		3427	=item w->set (object *)
		3428
		3429	This is a variation of a method callback - leaving out the method to call
		3430	will default the method to C<operator ()>, which makes it possible to use
		3431	functor objects without having to manually specify the C<operator ()> all
		3432	the time. Incidentally, you can then also leave out the template argument
		3433	list.
		3434
		3435	The C<operator ()> method prototype must be C<void operator ()(watcher &w,
		3436	int revents)>.
		3437
		3438	See the method-C<set> above for more details.
		3439
		3440	Example: use a functor object as callback.
		3441
		3442	struct myfunctor
		3443	{
		3444	void operator() (ev::io &w, int revents)
		3445	{
		3446	...
		3447	}
		3448	}
		3449
		3450	myfunctor f;
		3451
		3452	ev::io w;
		3453	w.set (&f);
		3454
2850	=item w->set<function> (void *data = 0)	3455	=item w->set<function> (void *data = 0)
2851		3456
2852	Also sets a callback, but uses a static method or plain function as	3457	Also sets a callback, but uses a static method or plain function as
2853	callback. The optional C<data> argument will be stored in the watcher's	3458	callback. The optional C<data> argument will be stored in the watcher's
2854	C<data> member and is free for you to use.	3459	C<data> member and is free for you to use.
…		…
2860	Example: Use a plain function as callback.	3465	Example: Use a plain function as callback.
2861		3466
2862	static void io_cb (ev::io &w, int revents) { }	3467	static void io_cb (ev::io &w, int revents) { }
2863	iow.set <io_cb> ();	3468	iow.set <io_cb> ();
2864		3469
2865	=item w->set (struct ev_loop *)	3470	=item w->set (loop)
2866		3471
2867	Associates a different C<struct ev_loop> with this watcher. You can only	3472	Associates a different C<struct ev_loop> with this watcher. You can only
2868	do this when the watcher is inactive (and not pending either).	3473	do this when the watcher is inactive (and not pending either).
2869		3474
2870	=item w->set ([arguments])	3475	=item w->set ([arguments])
2871		3476
2872	Basically the same as C<ev_TYPE_set>, with the same arguments. Must be	3477	Basically the same as C<ev_TYPE_set>, with the same arguments. Either this
2873	called at least once. Unlike the C counterpart, an active watcher gets	3478	method or a suitable start method must be called at least once. Unlike the
2874	automatically stopped and restarted when reconfiguring it with this	3479	C counterpart, an active watcher gets automatically stopped and restarted
2875	method.	3480	when reconfiguring it with this method.
2876		3481
2877	=item w->start ()	3482	=item w->start ()
2878		3483
2879	Starts the watcher. Note that there is no C<loop> argument, as the	3484	Starts the watcher. Note that there is no C<loop> argument, as the
2880	constructor already stores the event loop.	3485	constructor already stores the event loop.
2881		3486
		3487	=item w->start ([arguments])
		3488
		3489	Instead of calling C<set> and C<start> methods separately, it is often
		3490	convenient to wrap them in one call. Uses the same type of arguments as
		3491	the configure C<set> method of the watcher.
		3492
2882	=item w->stop ()	3493	=item w->stop ()
2883		3494
2884	Stops the watcher if it is active. Again, no C<loop> argument.	3495	Stops the watcher if it is active. Again, no C<loop> argument.
2885		3496
2886	=item w->again () (C<ev::timer>, C<ev::periodic> only)	3497	=item w->again () (C<ev::timer>, C<ev::periodic> only)
…		…
2898		3509
2899	=back	3510	=back
2900		3511
2901	=back	3512	=back
2902		3513
2903	Example: Define a class with an IO and idle watcher, start one of them in	3514	Example: Define a class with two I/O and idle watchers, start the I/O
2904	the constructor.	3515	watchers in the constructor.
2905		3516
2906	class myclass	3517	class myclass
2907	{	3518	{
2908	ev::io io ; void io_cb (ev::io &w, int revents);	3519	ev::io io ; void io_cb (ev::io &w, int revents);
		3520	ev::io2 io2 ; void io2_cb (ev::io &w, int revents);
2909	ev::idle idle; void idle_cb (ev::idle &w, int revents);	3521	ev::idle idle; void idle_cb (ev::idle &w, int revents);
2910		3522
2911	myclass (int fd)	3523	myclass (int fd)
2912	{	3524	{
2913	io .set <myclass, &myclass::io_cb > (this);	3525	io .set <myclass, &myclass::io_cb > (this);
		3526	io2 .set <myclass, &myclass::io2_cb > (this);
2914	idle.set <myclass, &myclass::idle_cb> (this);	3527	idle.set <myclass, &myclass::idle_cb> (this);
2915		3528
2916	io.start (fd, ev::READ);	3529	io.set (fd, ev::WRITE); // configure the watcher
		3530	io.start (); // start it whenever convenient
		3531
		3532	io2.start (fd, ev::READ); // set + start in one call
2917	}	3533	}
2918	};	3534	};
2919		3535
2920		3536
2921	=head1 OTHER LANGUAGE BINDINGS	3537	=head1 OTHER LANGUAGE BINDINGS
…		…
2940	L<http://software.schmorp.de/pkg/EV>.	3556	L<http://software.schmorp.de/pkg/EV>.
2941		3557
2942	=item Python	3558	=item Python
2943		3559
2944	Python bindings can be found at L<http://code.google.com/p/pyev/>. It	3560	Python bindings can be found at L<http://code.google.com/p/pyev/>. It
2945	seems to be quite complete and well-documented. Note, however, that the	3561	seems to be quite complete and well-documented.
2946	patch they require for libev is outright dangerous as it breaks the ABI
2947	for everybody else, and therefore, should never be applied in an installed
2948	libev (if python requires an incompatible ABI then it needs to embed
2949	libev).
2950		3562
2951	=item Ruby	3563	=item Ruby
2952		3564
2953	Tony Arcieri has written a ruby extension that offers access to a subset	3565	Tony Arcieri has written a ruby extension that offers access to a subset
2954	of the libev API and adds file handle abstractions, asynchronous DNS and	3566	of the libev API and adds file handle abstractions, asynchronous DNS and
2955	more on top of it. It can be found via gem servers. Its homepage is at	3567	more on top of it. It can be found via gem servers. Its homepage is at
2956	L<http://rev.rubyforge.org/>.	3568	L<http://rev.rubyforge.org/>.
2957		3569
		3570	Roger Pack reports that using the link order C<-lws2_32 -lmsvcrt-ruby-190>
		3571	makes rev work even on mingw.
		3572
		3573	=item Haskell
		3574
		3575	A haskell binding to libev is available at
		3576	L<http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hlibev>.
		3577
2958	=item D	3578	=item D
2959		3579
2960	Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to	3580	Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to
2961	be found at L<http://proj.llucax.com.ar/wiki/evd>.	3581	be found at L<http://proj.llucax.com.ar/wiki/evd>.
2962		3582
2963	=item Ocaml	3583	=item Ocaml
2964		3584
2965	Erkki Seppala has written Ocaml bindings for libev, to be found at	3585	Erkki Seppala has written Ocaml bindings for libev, to be found at
2966	L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>.	3586	L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>.
		3587
		3588	=item Lua
		3589
		3590	Brian Maher has written a partial interface to libev for lua (at the
		3591	time of this writing, only C<ev_io> and C<ev_timer>), to be found at
		3592	L<http://github.com/brimworks/lua-ev>.
2967		3593
2968	=back	3594	=back
2969		3595
2970		3596
2971	=head1 MACRO MAGIC	3597	=head1 MACRO MAGIC
…		…
2985	loop argument"). The C<EV_A> form is used when this is the sole argument,	3611	loop argument"). The C<EV_A> form is used when this is the sole argument,
2986	C<EV_A_> is used when other arguments are following. Example:	3612	C<EV_A_> is used when other arguments are following. Example:
2987		3613
2988	ev_unref (EV_A);	3614	ev_unref (EV_A);
2989	ev_timer_add (EV_A_ watcher);	3615	ev_timer_add (EV_A_ watcher);
2990	ev_loop (EV_A_ 0);	3616	ev_run (EV_A_ 0);
2991		3617
2992	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	3618	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
2993	which is often provided by the following macro.	3619	which is often provided by the following macro.
2994		3620
2995	=item C<EV_P>, C<EV_P_>	3621	=item C<EV_P>, C<EV_P_>
…		…
3035	}	3661	}
3036		3662
3037	ev_check check;	3663	ev_check check;
3038	ev_check_init (&check, check_cb);	3664	ev_check_init (&check, check_cb);
3039	ev_check_start (EV_DEFAULT_ &check);	3665	ev_check_start (EV_DEFAULT_ &check);
3040	ev_loop (EV_DEFAULT_ 0);	3666	ev_run (EV_DEFAULT_ 0);
3041		3667
3042	=head1 EMBEDDING	3668	=head1 EMBEDDING
3043		3669
3044	Libev can (and often is) directly embedded into host	3670	Libev can (and often is) directly embedded into host
3045	applications. Examples of applications that embed it include the Deliantra	3671	applications. Examples of applications that embed it include the Deliantra
…		…
3072		3698
3073	#define EV_STANDALONE 1	3699	#define EV_STANDALONE 1
3074	#include "ev.h"	3700	#include "ev.h"
3075		3701
3076	Both header files and implementation files can be compiled with a C++	3702	Both header files and implementation files can be compiled with a C++
3077	compiler (at least, thats a stated goal, and breakage will be treated	3703	compiler (at least, that's a stated goal, and breakage will be treated
3078	as a bug).	3704	as a bug).
3079		3705
3080	You need the following files in your source tree, or in a directory	3706	You need the following files in your source tree, or in a directory
3081	in your include path (e.g. in libev/ when using -Ilibev):	3707	in your include path (e.g. in libev/ when using -Ilibev):
3082		3708
…		…
3125	libev.m4	3751	libev.m4
3126		3752
3127	=head2 PREPROCESSOR SYMBOLS/MACROS	3753	=head2 PREPROCESSOR SYMBOLS/MACROS
3128		3754
3129	Libev can be configured via a variety of preprocessor symbols you have to	3755	Libev can be configured via a variety of preprocessor symbols you have to
3130	define before including any of its files. The default in the absence of	3756	define before including (or compiling) any of its files. The default in
3131	autoconf is documented for every option.	3757	the absence of autoconf is documented for every option.
		3758
		3759	Symbols marked with "(h)" do not change the ABI, and can have different
		3760	values when compiling libev vs. including F<ev.h>, so it is permissible
		3761	to redefine them before including F<ev.h> without breaking compatibility
		3762	to a compiled library. All other symbols change the ABI, which means all
		3763	users of libev and the libev code itself must be compiled with compatible
		3764	settings.
3132		3765
3133	=over 4	3766	=over 4
3134		3767
		3768	=item EV_COMPAT3 (h)
		3769
		3770	Backwards compatibility is a major concern for libev. This is why this
		3771	release of libev comes with wrappers for the functions and symbols that
		3772	have been renamed between libev version 3 and 4.
		3773
		3774	You can disable these wrappers (to test compatibility with future
		3775	versions) by defining C<EV_COMPAT3> to C<0> when compiling your
		3776	sources. This has the additional advantage that you can drop the C<struct>
		3777	from C<struct ev_loop> declarations, as libev will provide an C<ev_loop>
		3778	typedef in that case.
		3779
		3780	In some future version, the default for C<EV_COMPAT3> will become C<0>,
		3781	and in some even more future version the compatibility code will be
		3782	removed completely.
		3783
3135	=item EV_STANDALONE	3784	=item EV_STANDALONE (h)
3136		3785
3137	Must always be C<1> if you do not use autoconf configuration, which	3786	Must always be C<1> if you do not use autoconf configuration, which
3138	keeps libev from including F<config.h>, and it also defines dummy	3787	keeps libev from including F<config.h>, and it also defines dummy
3139	implementations for some libevent functions (such as logging, which is not	3788	implementations for some libevent functions (such as logging, which is not
3140	supported). It will also not define any of the structs usually found in	3789	supported). It will also not define any of the structs usually found in
3141	F<event.h> that are not directly supported by the libev core alone.	3790	F<event.h> that are not directly supported by the libev core alone.
3142		3791
		3792	In standalone mode, libev will still try to automatically deduce the
		3793	configuration, but has to be more conservative.
		3794
3143	=item EV_USE_MONOTONIC	3795	=item EV_USE_MONOTONIC
3144		3796
3145	If defined to be C<1>, libev will try to detect the availability of the	3797	If defined to be C<1>, libev will try to detect the availability of the
3146	monotonic clock option at both compile time and runtime. Otherwise no use	3798	monotonic clock option at both compile time and runtime. Otherwise no
3147	of the monotonic clock option will be attempted. If you enable this, you	3799	use of the monotonic clock option will be attempted. If you enable this,
3148	usually have to link against librt or something similar. Enabling it when	3800	you usually have to link against librt or something similar. Enabling it
3149	the functionality isn't available is safe, though, although you have	3801	when the functionality isn't available is safe, though, although you have
3150	to make sure you link against any libraries where the C<clock_gettime>	3802	to make sure you link against any libraries where the C<clock_gettime>
3151	function is hiding in (often F<-lrt>).	3803	function is hiding in (often F<-lrt>). See also C<EV_USE_CLOCK_SYSCALL>.
3152		3804
3153	=item EV_USE_REALTIME	3805	=item EV_USE_REALTIME
3154		3806
3155	If defined to be C<1>, libev will try to detect the availability of the	3807	If defined to be C<1>, libev will try to detect the availability of the
3156	real-time clock option at compile time (and assume its availability at	3808	real-time clock option at compile time (and assume its availability
3157	runtime if successful). Otherwise no use of the real-time clock option will	3809	at runtime if successful). Otherwise no use of the real-time clock
3158	be attempted. This effectively replaces C<gettimeofday> by C<clock_get	3810	option will be attempted. This effectively replaces C<gettimeofday>
3159	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the	3811	by C<clock_get (CLOCK_REALTIME, ...)> and will not normally affect
3160	note about libraries in the description of C<EV_USE_MONOTONIC>, though.	3812	correctness. See the note about libraries in the description of
		3813	C<EV_USE_MONOTONIC>, though. Defaults to the opposite value of
		3814	C<EV_USE_CLOCK_SYSCALL>.
		3815
		3816	=item EV_USE_CLOCK_SYSCALL
		3817
		3818	If defined to be C<1>, libev will try to use a direct syscall instead
		3819	of calling the system-provided C<clock_gettime> function. This option
		3820	exists because on GNU/Linux, C<clock_gettime> is in C<librt>, but C<librt>
		3821	unconditionally pulls in C<libpthread>, slowing down single-threaded
		3822	programs needlessly. Using a direct syscall is slightly slower (in
		3823	theory), because no optimised vdso implementation can be used, but avoids
		3824	the pthread dependency. Defaults to C<1> on GNU/Linux with glibc 2.x or
		3825	higher, as it simplifies linking (no need for C<-lrt>).
3161		3826
3162	=item EV_USE_NANOSLEEP	3827	=item EV_USE_NANOSLEEP
3163		3828
3164	If defined to be C<1>, libev will assume that C<nanosleep ()> is available	3829	If defined to be C<1>, libev will assume that C<nanosleep ()> is available
3165	and will use it for delays. Otherwise it will use C<select ()>.	3830	and will use it for delays. Otherwise it will use C<select ()>.
…		…
3181		3846
3182	=item EV_SELECT_USE_FD_SET	3847	=item EV_SELECT_USE_FD_SET
3183		3848
3184	If defined to C<1>, then the select backend will use the system C<fd_set>	3849	If defined to C<1>, then the select backend will use the system C<fd_set>
3185	structure. This is useful if libev doesn't compile due to a missing	3850	structure. This is useful if libev doesn't compile due to a missing
3186	C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout on	3851	C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout
3187	exotic systems. This usually limits the range of file descriptors to some	3852	on exotic systems. This usually limits the range of file descriptors to
3188	low limit such as 1024 or might have other limitations (winsocket only	3853	some low limit such as 1024 or might have other limitations (winsocket
3189	allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might	3854	only allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation,
3190	influence the size of the C<fd_set> used.	3855	configures the maximum size of the C<fd_set>.
3191		3856
3192	=item EV_SELECT_IS_WINSOCKET	3857	=item EV_SELECT_IS_WINSOCKET
3193		3858
3194	When defined to C<1>, the select backend will assume that	3859	When defined to C<1>, the select backend will assume that
3195	select/socket/connect etc. don't understand file descriptors but	3860	select/socket/connect etc. don't understand file descriptors but
…		…
3197	be used is the winsock select). This means that it will call	3862	be used is the winsock select). This means that it will call
3198	C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise,	3863	C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise,
3199	it is assumed that all these functions actually work on fds, even	3864	it is assumed that all these functions actually work on fds, even
3200	on win32. Should not be defined on non-win32 platforms.	3865	on win32. Should not be defined on non-win32 platforms.
3201		3866
3202	=item EV_FD_TO_WIN32_HANDLE	3867	=item EV_FD_TO_WIN32_HANDLE(fd)
3203		3868
3204	If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map	3869	If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map
3205	file descriptors to socket handles. When not defining this symbol (the	3870	file descriptors to socket handles. When not defining this symbol (the
3206	default), then libev will call C<_get_osfhandle>, which is usually	3871	default), then libev will call C<_get_osfhandle>, which is usually
3207	correct. In some cases, programs use their own file descriptor management,	3872	correct. In some cases, programs use their own file descriptor management,
3208	in which case they can provide this function to map fds to socket handles.	3873	in which case they can provide this function to map fds to socket handles.
		3874
		3875	=item EV_WIN32_HANDLE_TO_FD(handle)
		3876
		3877	If C<EV_SELECT_IS_WINSOCKET> then libev maps handles to file descriptors
		3878	using the standard C<_open_osfhandle> function. For programs implementing
		3879	their own fd to handle mapping, overwriting this function makes it easier
		3880	to do so. This can be done by defining this macro to an appropriate value.
		3881
		3882	=item EV_WIN32_CLOSE_FD(fd)
		3883
		3884	If programs implement their own fd to handle mapping on win32, then this
		3885	macro can be used to override the C<close> function, useful to unregister
		3886	file descriptors again. Note that the replacement function has to close
		3887	the underlying OS handle.
3209		3888
3210	=item EV_USE_POLL	3889	=item EV_USE_POLL
3211		3890
3212	If defined to be C<1>, libev will compile in support for the C<poll>(2)	3891	If defined to be C<1>, libev will compile in support for the C<poll>(2)
3213	backend. Otherwise it will be enabled on non-win32 platforms. It	3892	backend. Otherwise it will be enabled on non-win32 platforms. It
…		…
3260	as well as for signal and thread safety in C<ev_async> watchers.	3939	as well as for signal and thread safety in C<ev_async> watchers.
3261		3940
3262	In the absence of this define, libev will use C<sig_atomic_t volatile>	3941	In the absence of this define, libev will use C<sig_atomic_t volatile>
3263	(from F<signal.h>), which is usually good enough on most platforms.	3942	(from F<signal.h>), which is usually good enough on most platforms.
3264		3943
3265	=item EV_H	3944	=item EV_H (h)
3266		3945
3267	The name of the F<ev.h> header file used to include it. The default if	3946	The name of the F<ev.h> header file used to include it. The default if
3268	undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be	3947	undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be
3269	used to virtually rename the F<ev.h> header file in case of conflicts.	3948	used to virtually rename the F<ev.h> header file in case of conflicts.
3270		3949
3271	=item EV_CONFIG_H	3950	=item EV_CONFIG_H (h)
3272		3951
3273	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override	3952	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override
3274	F<ev.c>'s idea of where to find the F<config.h> file, similarly to	3953	F<ev.c>'s idea of where to find the F<config.h> file, similarly to
3275	C<EV_H>, above.	3954	C<EV_H>, above.
3276		3955
3277	=item EV_EVENT_H	3956	=item EV_EVENT_H (h)
3278		3957
3279	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea	3958	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea
3280	of how the F<event.h> header can be found, the default is C<"event.h">.	3959	of how the F<event.h> header can be found, the default is C<"event.h">.
3281		3960
3282	=item EV_PROTOTYPES	3961	=item EV_PROTOTYPES (h)
3283		3962
3284	If defined to be C<0>, then F<ev.h> will not define any function	3963	If defined to be C<0>, then F<ev.h> will not define any function
3285	prototypes, but still define all the structs and other symbols. This is	3964	prototypes, but still define all the structs and other symbols. This is
3286	occasionally useful if you want to provide your own wrapper functions	3965	occasionally useful if you want to provide your own wrapper functions
3287	around libev functions.	3966	around libev functions.
…		…
3309	fine.	3988	fine.
3310		3989
3311	If your embedding application does not need any priorities, defining these	3990	If your embedding application does not need any priorities, defining these
3312	both to C<0> will save some memory and CPU.	3991	both to C<0> will save some memory and CPU.
3313		3992
3314	=item EV_PERIODIC_ENABLE	3993	=item EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE,
		3994	EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE,
		3995	EV_ASYNC_ENABLE, EV_CHILD_ENABLE.
3315		3996
3316	If undefined or defined to be C<1>, then periodic timers are supported. If	3997	If undefined or defined to be C<1> (and the platform supports it), then
3317	defined to be C<0>, then they are not. Disabling them saves a few kB of	3998	the respective watcher type is supported. If defined to be C<0>, then it
3318	code.	3999	is not. Disabling watcher types mainly saves code size.
3319		4000
3320	=item EV_IDLE_ENABLE	4001	=item EV_FEATURES
3321
3322	If undefined or defined to be C<1>, then idle watchers are supported. If
3323	defined to be C<0>, then they are not. Disabling them saves a few kB of
3324	code.
3325
3326	=item EV_EMBED_ENABLE
3327
3328	If undefined or defined to be C<1>, then embed watchers are supported. If
3329	defined to be C<0>, then they are not. Embed watchers rely on most other
3330	watcher types, which therefore must not be disabled.
3331
3332	=item EV_STAT_ENABLE
3333
3334	If undefined or defined to be C<1>, then stat watchers are supported. If
3335	defined to be C<0>, then they are not.
3336
3337	=item EV_FORK_ENABLE
3338
3339	If undefined or defined to be C<1>, then fork watchers are supported. If
3340	defined to be C<0>, then they are not.
3341
3342	=item EV_ASYNC_ENABLE
3343
3344	If undefined or defined to be C<1>, then async watchers are supported. If
3345	defined to be C<0>, then they are not.
3346
3347	=item EV_MINIMAL
3348		4002
3349	If you need to shave off some kilobytes of code at the expense of some	4003	If you need to shave off some kilobytes of code at the expense of some
3350	speed, define this symbol to C<1>. Currently this is used to override some	4004	speed (but with the full API), you can define this symbol to request
3351	inlining decisions, saves roughly 30% code size on amd64. It also selects a	4005	certain subsets of functionality. The default is to enable all features
3352	much smaller 2-heap for timer management over the default 4-heap.	4006	that can be enabled on the platform.
		4007
		4008	A typical way to use this symbol is to define it to C<0> (or to a bitset
		4009	with some broad features you want) and then selectively re-enable
		4010	additional parts you want, for example if you want everything minimal,
		4011	but multiple event loop support, async and child watchers and the poll
		4012	backend, use this:
		4013
		4014	#define EV_FEATURES 0
		4015	#define EV_MULTIPLICITY 1
		4016	#define EV_USE_POLL 1
		4017	#define EV_CHILD_ENABLE 1
		4018	#define EV_ASYNC_ENABLE 1
		4019
		4020	The actual value is a bitset, it can be a combination of the following
		4021	values:
		4022
		4023	=over 4
		4024
		4025	=item C<1> - faster/larger code
		4026
		4027	Use larger code to speed up some operations.
		4028
		4029	Currently this is used to override some inlining decisions (enlarging the
		4030	code size by roughly 30% on amd64).
		4031
		4032	When optimising for size, use of compiler flags such as C<-Os> with
		4033	gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of
		4034	assertions.
		4035
		4036	=item C<2> - faster/larger data structures
		4037
		4038	Replaces the small 2-heap for timer management by a faster 4-heap, larger
		4039	hash table sizes and so on. This will usually further increase code size
		4040	and can additionally have an effect on the size of data structures at
		4041	runtime.
		4042
		4043	=item C<4> - full API configuration
		4044
		4045	This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and
		4046	enables multiplicity (C<EV_MULTIPLICITY>=1).
		4047
		4048	=item C<8> - full API
		4049
		4050	This enables a lot of the "lesser used" API functions. See C<ev.h> for
		4051	details on which parts of the API are still available without this
		4052	feature, and do not complain if this subset changes over time.
		4053
		4054	=item C<16> - enable all optional watcher types
		4055
		4056	Enables all optional watcher types. If you want to selectively enable
		4057	only some watcher types other than I/O and timers (e.g. prepare,
		4058	embed, async, child...) you can enable them manually by defining
		4059	C<EV_watchertype_ENABLE> to C<1> instead.
		4060
		4061	=item C<32> - enable all backends
		4062
		4063	This enables all backends - without this feature, you need to enable at
		4064	least one backend manually (C<EV_USE_SELECT> is a good choice).
		4065
		4066	=item C<64> - enable OS-specific "helper" APIs
		4067
		4068	Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by
		4069	default.
		4070
		4071	=back
		4072
		4073	Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0>
		4074	reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb
		4075	code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O
		4076	watchers, timers and monotonic clock support.
		4077
		4078	With an intelligent-enough linker (gcc+binutils are intelligent enough
		4079	when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by
		4080	your program might be left out as well - a binary starting a timer and an
		4081	I/O watcher then might come out at only 5Kb.
		4082
		4083	=item EV_AVOID_STDIO
		4084
		4085	If this is set to C<1> at compiletime, then libev will avoid using stdio
		4086	functions (printf, scanf, perror etc.). This will increase the code size
		4087	somewhat, but if your program doesn't otherwise depend on stdio and your
		4088	libc allows it, this avoids linking in the stdio library which is quite
		4089	big.
		4090
		4091	Note that error messages might become less precise when this option is
		4092	enabled.
		4093
		4094	=item EV_NSIG
		4095
		4096	The highest supported signal number, +1 (or, the number of
		4097	signals): Normally, libev tries to deduce the maximum number of signals
		4098	automatically, but sometimes this fails, in which case it can be
		4099	specified. Also, using a lower number than detected (C<32> should be
		4100	good for about any system in existence) can save some memory, as libev
		4101	statically allocates some 12-24 bytes per signal number.
3353		4102
3354	=item EV_PID_HASHSIZE	4103	=item EV_PID_HASHSIZE
3355		4104
3356	C<ev_child> watchers use a small hash table to distribute workload by	4105	C<ev_child> watchers use a small hash table to distribute workload by
3357	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more	4106	pid. The default size is C<16> (or C<1> with C<EV_FEATURES> disabled),
3358	than enough. If you need to manage thousands of children you might want to	4107	usually more than enough. If you need to manage thousands of children you
3359	increase this value (I<must> be a power of two).	4108	might want to increase this value (I<must> be a power of two).
3360		4109
3361	=item EV_INOTIFY_HASHSIZE	4110	=item EV_INOTIFY_HASHSIZE
3362		4111
3363	C<ev_stat> watchers use a small hash table to distribute workload by	4112	C<ev_stat> watchers use a small hash table to distribute workload by
3364	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),	4113	inotify watch id. The default size is C<16> (or C<1> with C<EV_FEATURES>
3365	usually more than enough. If you need to manage thousands of C<ev_stat>	4114	disabled), usually more than enough. If you need to manage thousands of
3366	watchers you might want to increase this value (I<must> be a power of	4115	C<ev_stat> watchers you might want to increase this value (I<must> be a
3367	two).	4116	power of two).
3368		4117
3369	=item EV_USE_4HEAP	4118	=item EV_USE_4HEAP
3370		4119
3371	Heaps are not very cache-efficient. To improve the cache-efficiency of the	4120	Heaps are not very cache-efficient. To improve the cache-efficiency of the
3372	timer and periodics heaps, libev uses a 4-heap when this symbol is defined	4121	timer and periodics heaps, libev uses a 4-heap when this symbol is defined
3373	to C<1>. The 4-heap uses more complicated (longer) code but has noticeably	4122	to C<1>. The 4-heap uses more complicated (longer) code but has noticeably
3374	faster performance with many (thousands) of watchers.	4123	faster performance with many (thousands) of watchers.
3375		4124
3376	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>	4125	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3377	(disabled).	4126	will be C<0>.
3378		4127
3379	=item EV_HEAP_CACHE_AT	4128	=item EV_HEAP_CACHE_AT
3380		4129
3381	Heaps are not very cache-efficient. To improve the cache-efficiency of the	4130	Heaps are not very cache-efficient. To improve the cache-efficiency of the
3382	timer and periodics heaps, libev can cache the timestamp (I<at>) within	4131	timer and periodics heaps, libev can cache the timestamp (I<at>) within
3383	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),	4132	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),
3384	which uses 8-12 bytes more per watcher and a few hundred bytes more code,	4133	which uses 8-12 bytes more per watcher and a few hundred bytes more code,
3385	but avoids random read accesses on heap changes. This improves performance	4134	but avoids random read accesses on heap changes. This improves performance
3386	noticeably with many (hundreds) of watchers.	4135	noticeably with many (hundreds) of watchers.
3387		4136
3388	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>	4137	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3389	(disabled).	4138	will be C<0>.
3390		4139
3391	=item EV_VERIFY	4140	=item EV_VERIFY
3392		4141
3393	Controls how much internal verification (see C<ev_loop_verify ()>) will	4142	Controls how much internal verification (see C<ev_verify ()>) will
3394	be done: If set to C<0>, no internal verification code will be compiled	4143	be done: If set to C<0>, no internal verification code will be compiled
3395	in. If set to C<1>, then verification code will be compiled in, but not	4144	in. If set to C<1>, then verification code will be compiled in, but not
3396	called. If set to C<2>, then the internal verification code will be	4145	called. If set to C<2>, then the internal verification code will be
3397	called once per loop, which can slow down libev. If set to C<3>, then the	4146	called once per loop, which can slow down libev. If set to C<3>, then the
3398	verification code will be called very frequently, which will slow down	4147	verification code will be called very frequently, which will slow down
3399	libev considerably.	4148	libev considerably.
3400		4149
3401	The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be	4150	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3402	C<0>.	4151	will be C<0>.
3403		4152
3404	=item EV_COMMON	4153	=item EV_COMMON
3405		4154
3406	By default, all watchers have a C<void *data> member. By redefining	4155	By default, all watchers have a C<void *data> member. By redefining
3407	this macro to a something else you can include more and other types of	4156	this macro to something else you can include more and other types of
3408	members. You have to define it each time you include one of the files,	4157	members. You have to define it each time you include one of the files,
3409	though, and it must be identical each time.	4158	though, and it must be identical each time.
3410		4159
3411	For example, the perl EV module uses something like this:	4160	For example, the perl EV module uses something like this:
3412		4161
…		…
3465	file.	4214	file.
3466		4215
3467	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	4216	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
3468	that everybody includes and which overrides some configure choices:	4217	that everybody includes and which overrides some configure choices:
3469		4218
3470	#define EV_MINIMAL 1	4219	#define EV_FEATURES 8
3471	#define EV_USE_POLL 0	4220	#define EV_USE_SELECT 1
3472	#define EV_MULTIPLICITY 0
3473	#define EV_PERIODIC_ENABLE 0	4221	#define EV_PREPARE_ENABLE 1
		4222	#define EV_IDLE_ENABLE 1
3474	#define EV_STAT_ENABLE 0	4223	#define EV_SIGNAL_ENABLE 1
3475	#define EV_FORK_ENABLE 0	4224	#define EV_CHILD_ENABLE 1
		4225	#define EV_USE_STDEXCEPT 0
3476	#define EV_CONFIG_H <config.h>	4226	#define EV_CONFIG_H <config.h>
3477	#define EV_MINPRI 0
3478	#define EV_MAXPRI 0
3479		4227
3480	#include "ev++.h"	4228	#include "ev++.h"
3481		4229
3482	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	4230	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
3483		4231
…		…
3543	default loop and triggering an C<ev_async> watcher from the default loop	4291	default loop and triggering an C<ev_async> watcher from the default loop
3544	watcher callback into the event loop interested in the signal.	4292	watcher callback into the event loop interested in the signal.
3545		4293
3546	=back	4294	=back
3547		4295
		4296	=head4 THREAD LOCKING EXAMPLE
		4297
		4298	Here is a fictitious example of how to run an event loop in a different
		4299	thread than where callbacks are being invoked and watchers are
		4300	created/added/removed.
		4301
		4302	For a real-world example, see the C<EV::Loop::Async> perl module,
		4303	which uses exactly this technique (which is suited for many high-level
		4304	languages).
		4305
		4306	The example uses a pthread mutex to protect the loop data, a condition
		4307	variable to wait for callback invocations, an async watcher to notify the
		4308	event loop thread and an unspecified mechanism to wake up the main thread.
		4309
		4310	First, you need to associate some data with the event loop:
		4311
		4312	typedef struct {
		4313	mutex_t lock; /* global loop lock */
		4314	ev_async async_w;
		4315	thread_t tid;
		4316	cond_t invoke_cv;
		4317	} userdata;
		4318
		4319	void prepare_loop (EV_P)
		4320	{
		4321	// for simplicity, we use a static userdata struct.
		4322	static userdata u;
		4323
		4324	ev_async_init (&u->async_w, async_cb);
		4325	ev_async_start (EV_A_ &u->async_w);
		4326
		4327	pthread_mutex_init (&u->lock, 0);
		4328	pthread_cond_init (&u->invoke_cv, 0);
		4329
		4330	// now associate this with the loop
		4331	ev_set_userdata (EV_A_ u);
		4332	ev_set_invoke_pending_cb (EV_A_ l_invoke);
		4333	ev_set_loop_release_cb (EV_A_ l_release, l_acquire);
		4334
		4335	// then create the thread running ev_loop
		4336	pthread_create (&u->tid, 0, l_run, EV_A);
		4337	}
		4338
		4339	The callback for the C<ev_async> watcher does nothing: the watcher is used
		4340	solely to wake up the event loop so it takes notice of any new watchers
		4341	that might have been added:
		4342
		4343	static void
		4344	async_cb (EV_P_ ev_async *w, int revents)
		4345	{
		4346	// just used for the side effects
		4347	}
		4348
		4349	The C<l_release> and C<l_acquire> callbacks simply unlock/lock the mutex
		4350	protecting the loop data, respectively.
		4351
		4352	static void
		4353	l_release (EV_P)
		4354	{
		4355	userdata *u = ev_userdata (EV_A);
		4356	pthread_mutex_unlock (&u->lock);
		4357	}
		4358
		4359	static void
		4360	l_acquire (EV_P)
		4361	{
		4362	userdata *u = ev_userdata (EV_A);
		4363	pthread_mutex_lock (&u->lock);
		4364	}
		4365
		4366	The event loop thread first acquires the mutex, and then jumps straight
		4367	into C<ev_run>:
		4368
		4369	void *
		4370	l_run (void *thr_arg)
		4371	{
		4372	struct ev_loop *loop = (struct ev_loop *)thr_arg;
		4373
		4374	l_acquire (EV_A);
		4375	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
		4376	ev_run (EV_A_ 0);
		4377	l_release (EV_A);
		4378
		4379	return 0;
		4380	}
		4381
		4382	Instead of invoking all pending watchers, the C<l_invoke> callback will
		4383	signal the main thread via some unspecified mechanism (signals? pipe
		4384	writes? C<Async::Interrupt>?) and then waits until all pending watchers
		4385	have been called (in a while loop because a) spurious wakeups are possible
		4386	and b) skipping inter-thread-communication when there are no pending
		4387	watchers is very beneficial):
		4388
		4389	static void
		4390	l_invoke (EV_P)
		4391	{
		4392	userdata *u = ev_userdata (EV_A);
		4393
		4394	while (ev_pending_count (EV_A))
		4395	{
		4396	wake_up_other_thread_in_some_magic_or_not_so_magic_way ();
		4397	pthread_cond_wait (&u->invoke_cv, &u->lock);
		4398	}
		4399	}
		4400
		4401	Now, whenever the main thread gets told to invoke pending watchers, it
		4402	will grab the lock, call C<ev_invoke_pending> and then signal the loop
		4403	thread to continue:
		4404
		4405	static void
		4406	real_invoke_pending (EV_P)
		4407	{
		4408	userdata *u = ev_userdata (EV_A);
		4409
		4410	pthread_mutex_lock (&u->lock);
		4411	ev_invoke_pending (EV_A);
		4412	pthread_cond_signal (&u->invoke_cv);
		4413	pthread_mutex_unlock (&u->lock);
		4414	}
		4415
		4416	Whenever you want to start/stop a watcher or do other modifications to an
		4417	event loop, you will now have to lock:
		4418
		4419	ev_timer timeout_watcher;
		4420	userdata *u = ev_userdata (EV_A);
		4421
		4422	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
		4423
		4424	pthread_mutex_lock (&u->lock);
		4425	ev_timer_start (EV_A_ &timeout_watcher);
		4426	ev_async_send (EV_A_ &u->async_w);
		4427	pthread_mutex_unlock (&u->lock);
		4428
		4429	Note that sending the C<ev_async> watcher is required because otherwise
		4430	an event loop currently blocking in the kernel will have no knowledge
		4431	about the newly added timer. By waking up the loop it will pick up any new
		4432	watchers in the next event loop iteration.
		4433
3548	=head3 COROUTINES	4434	=head3 COROUTINES
3549		4435
3550	Libev is very accommodating to coroutines ("cooperative threads"):	4436	Libev is very accommodating to coroutines ("cooperative threads"):
3551	libev fully supports nesting calls to its functions from different	4437	libev fully supports nesting calls to its functions from different
3552	coroutines (e.g. you can call C<ev_loop> on the same loop from two	4438	coroutines (e.g. you can call C<ev_run> on the same loop from two
3553	different coroutines, and switch freely between both coroutines running the	4439	different coroutines, and switch freely between both coroutines running
3554	loop, as long as you don't confuse yourself). The only exception is that	4440	the loop, as long as you don't confuse yourself). The only exception is
3555	you must not do this from C<ev_periodic> reschedule callbacks.	4441	that you must not do this from C<ev_periodic> reschedule callbacks.
3556		4442
3557	Care has been taken to ensure that libev does not keep local state inside	4443	Care has been taken to ensure that libev does not keep local state inside
3558	C<ev_loop>, and other calls do not usually allow for coroutine switches as	4444	C<ev_run>, and other calls do not usually allow for coroutine switches as
3559	they do not clal any callbacks.	4445	they do not call any callbacks.
3560		4446
3561	=head2 COMPILER WARNINGS	4447	=head2 COMPILER WARNINGS
3562		4448
3563	Depending on your compiler and compiler settings, you might get no or a	4449	Depending on your compiler and compiler settings, you might get no or a
3564	lot of warnings when compiling libev code. Some people are apparently	4450	lot of warnings when compiling libev code. Some people are apparently
…		…
3574	maintainable.	4460	maintainable.
3575		4461
3576	And of course, some compiler warnings are just plain stupid, or simply	4462	And of course, some compiler warnings are just plain stupid, or simply
3577	wrong (because they don't actually warn about the condition their message	4463	wrong (because they don't actually warn about the condition their message
3578	seems to warn about). For example, certain older gcc versions had some	4464	seems to warn about). For example, certain older gcc versions had some
3579	warnings that resulted an extreme number of false positives. These have	4465	warnings that resulted in an extreme number of false positives. These have
3580	been fixed, but some people still insist on making code warn-free with	4466	been fixed, but some people still insist on making code warn-free with
3581	such buggy versions.	4467	such buggy versions.
3582		4468
3583	While libev is written to generate as few warnings as possible,	4469	While libev is written to generate as few warnings as possible,
3584	"warn-free" code is not a goal, and it is recommended not to build libev	4470	"warn-free" code is not a goal, and it is recommended not to build libev
…		…
3598	==2274== definitely lost: 0 bytes in 0 blocks.	4484	==2274== definitely lost: 0 bytes in 0 blocks.
3599	==2274== possibly lost: 0 bytes in 0 blocks.	4485	==2274== possibly lost: 0 bytes in 0 blocks.
3600	==2274== still reachable: 256 bytes in 1 blocks.	4486	==2274== still reachable: 256 bytes in 1 blocks.
3601		4487
3602	Then there is no memory leak, just as memory accounted to global variables	4488	Then there is no memory leak, just as memory accounted to global variables
3603	is not a memleak - the memory is still being refernced, and didn't leak.	4489	is not a memleak - the memory is still being referenced, and didn't leak.
3604		4490
3605	Similarly, under some circumstances, valgrind might report kernel bugs	4491	Similarly, under some circumstances, valgrind might report kernel bugs
3606	as if it were a bug in libev (e.g. in realloc or in the poll backend,	4492	as if it were a bug in libev (e.g. in realloc or in the poll backend,
3607	although an acceptable workaround has been found here), or it might be	4493	although an acceptable workaround has been found here), or it might be
3608	confused.	4494	confused.
…		…
3620	I suggest using suppression lists.	4506	I suggest using suppression lists.
3621		4507
3622		4508
3623	=head1 PORTABILITY NOTES	4509	=head1 PORTABILITY NOTES
3624		4510
		4511	=head2 GNU/LINUX 32 BIT LIMITATIONS
		4512
		4513	GNU/Linux is the only common platform that supports 64 bit file/large file
		4514	interfaces but I<disables> them by default.
		4515
		4516	That means that libev compiled in the default environment doesn't support
		4517	files larger than 2GiB or so, which mainly affects C<ev_stat> watchers.
		4518
		4519	Unfortunately, many programs try to work around this GNU/Linux issue
		4520	by enabling the large file API, which makes them incompatible with the
		4521	standard libev compiled for their system.
		4522
		4523	Likewise, libev cannot enable the large file API itself as this would
		4524	suddenly make it incompatible to the default compile time environment,
		4525	i.e. all programs not using special compile switches.
		4526
		4527	=head2 OS/X AND DARWIN BUGS
		4528
		4529	The whole thing is a bug if you ask me - basically any system interface
		4530	you touch is broken, whether it is locales, poll, kqueue or even the
		4531	OpenGL drivers.
		4532
		4533	=head3 C<kqueue> is buggy
		4534
		4535	The kqueue syscall is broken in all known versions - most versions support
		4536	only sockets, many support pipes.
		4537
		4538	Libev tries to work around this by not using C<kqueue> by default on this
		4539	rotten platform, but of course you can still ask for it when creating a
		4540	loop - embedding a socket-only kqueue loop into a select-based one is
		4541	probably going to work well.
		4542
		4543	=head3 C<poll> is buggy
		4544
		4545	Instead of fixing C<kqueue>, Apple replaced their (working) C<poll>
		4546	implementation by something calling C<kqueue> internally around the 10.5.6
		4547	release, so now C<kqueue> I<and> C<poll> are broken.
		4548
		4549	Libev tries to work around this by not using C<poll> by default on
		4550	this rotten platform, but of course you can still ask for it when creating
		4551	a loop.
		4552
		4553	=head3 C<select> is buggy
		4554
		4555	All that's left is C<select>, and of course Apple found a way to fuck this
		4556	one up as well: On OS/X, C<select> actively limits the number of file
		4557	descriptors you can pass in to 1024 - your program suddenly crashes when
		4558	you use more.
		4559
		4560	There is an undocumented "workaround" for this - defining
		4561	C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should>
		4562	work on OS/X.
		4563
		4564	=head2 SOLARIS PROBLEMS AND WORKAROUNDS
		4565
		4566	=head3 C<errno> reentrancy
		4567
		4568	The default compile environment on Solaris is unfortunately so
		4569	thread-unsafe that you can't even use components/libraries compiled
		4570	without C<-D_REENTRANT> in a threaded program, which, of course, isn't
		4571	defined by default. A valid, if stupid, implementation choice.
		4572
		4573	If you want to use libev in threaded environments you have to make sure
		4574	it's compiled with C<_REENTRANT> defined.
		4575
		4576	=head3 Event port backend
		4577
		4578	The scalable event interface for Solaris is called "event
		4579	ports". Unfortunately, this mechanism is very buggy in all major
		4580	releases. If you run into high CPU usage, your program freezes or you get
		4581	a large number of spurious wakeups, make sure you have all the relevant
		4582	and latest kernel patches applied. No, I don't know which ones, but there
		4583	are multiple ones to apply, and afterwards, event ports actually work
		4584	great.
		4585
		4586	If you can't get it to work, you can try running the program by setting
		4587	the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and
		4588	C<select> backends.
		4589
		4590	=head2 AIX POLL BUG
		4591
		4592	AIX unfortunately has a broken C<poll.h> header. Libev works around
		4593	this by trying to avoid the poll backend altogether (i.e. it's not even
		4594	compiled in), which normally isn't a big problem as C<select> works fine
		4595	with large bitsets on AIX, and AIX is dead anyway.
		4596
3625	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS	4597	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
		4598
		4599	=head3 General issues
3626		4600
3627	Win32 doesn't support any of the standards (e.g. POSIX) that libev	4601	Win32 doesn't support any of the standards (e.g. POSIX) that libev
3628	requires, and its I/O model is fundamentally incompatible with the POSIX	4602	requires, and its I/O model is fundamentally incompatible with the POSIX
3629	model. Libev still offers limited functionality on this platform in	4603	model. Libev still offers limited functionality on this platform in
3630	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	4604	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
3631	descriptors. This only applies when using Win32 natively, not when using	4605	descriptors. This only applies when using Win32 natively, not when using
3632	e.g. cygwin.	4606	e.g. cygwin. Actually, it only applies to the microsofts own compilers,
		4607	as every compielr comes with a slightly differently broken/incompatible
		4608	environment.
3633		4609
3634	Lifting these limitations would basically require the full	4610	Lifting these limitations would basically require the full
3635	re-implementation of the I/O system. If you are into these kinds of	4611	re-implementation of the I/O system. If you are into this kind of thing,
3636	things, then note that glib does exactly that for you in a very portable	4612	then note that glib does exactly that for you in a very portable way (note
3637	way (note also that glib is the slowest event library known to man).	4613	also that glib is the slowest event library known to man).
3638		4614
3639	There is no supported compilation method available on windows except	4615	There is no supported compilation method available on windows except
3640	embedding it into other applications.	4616	embedding it into other applications.
		4617
		4618	Sensible signal handling is officially unsupported by Microsoft - libev
		4619	tries its best, but under most conditions, signals will simply not work.
3641		4620
3642	Not a libev limitation but worth mentioning: windows apparently doesn't	4621	Not a libev limitation but worth mentioning: windows apparently doesn't
3643	accept large writes: instead of resulting in a partial write, windows will	4622	accept large writes: instead of resulting in a partial write, windows will
3644	either accept everything or return C<ENOBUFS> if the buffer is too large,	4623	either accept everything or return C<ENOBUFS> if the buffer is too large,
3645	so make sure you only write small amounts into your sockets (less than a	4624	so make sure you only write small amounts into your sockets (less than a
…		…
3650	the abysmal performance of winsockets, using a large number of sockets	4629	the abysmal performance of winsockets, using a large number of sockets
3651	is not recommended (and not reasonable). If your program needs to use	4630	is not recommended (and not reasonable). If your program needs to use
3652	more than a hundred or so sockets, then likely it needs to use a totally	4631	more than a hundred or so sockets, then likely it needs to use a totally
3653	different implementation for windows, as libev offers the POSIX readiness	4632	different implementation for windows, as libev offers the POSIX readiness
3654	notification model, which cannot be implemented efficiently on windows	4633	notification model, which cannot be implemented efficiently on windows
3655	(Microsoft monopoly games).	4634	(due to Microsoft monopoly games).
3656		4635
3657	A typical way to use libev under windows is to embed it (see the embedding	4636	A typical way to use libev under windows is to embed it (see the embedding
3658	section for details) and use the following F<evwrap.h> header file instead	4637	section for details) and use the following F<evwrap.h> header file instead
3659	of F<ev.h>:	4638	of F<ev.h>:
3660		4639
…		…
3667	you do I<not> compile the F<ev.c> or any other embedded source files!):	4646	you do I<not> compile the F<ev.c> or any other embedded source files!):
3668		4647
3669	#include "evwrap.h"	4648	#include "evwrap.h"
3670	#include "ev.c"	4649	#include "ev.c"
3671		4650
3672	=over 4
3673
3674	=item The winsocket select function	4651	=head3 The winsocket C<select> function
3675		4652
3676	The winsocket C<select> function doesn't follow POSIX in that it	4653	The winsocket C<select> function doesn't follow POSIX in that it
3677	requires socket I<handles> and not socket I<file descriptors> (it is	4654	requires socket I<handles> and not socket I<file descriptors> (it is
3678	also extremely buggy). This makes select very inefficient, and also	4655	also extremely buggy). This makes select very inefficient, and also
3679	requires a mapping from file descriptors to socket handles (the Microsoft	4656	requires a mapping from file descriptors to socket handles (the Microsoft
…		…
3688	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */	4665	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
3689		4666
3690	Note that winsockets handling of fd sets is O(n), so you can easily get a	4667	Note that winsockets handling of fd sets is O(n), so you can easily get a
3691	complexity in the O(n²) range when using win32.	4668	complexity in the O(n²) range when using win32.
3692		4669
3693	=item Limited number of file descriptors	4670	=head3 Limited number of file descriptors
3694		4671
3695	Windows has numerous arbitrary (and low) limits on things.	4672	Windows has numerous arbitrary (and low) limits on things.
3696		4673
3697	Early versions of winsocket's select only supported waiting for a maximum	4674	Early versions of winsocket's select only supported waiting for a maximum
3698	of C<64> handles (probably owning to the fact that all windows kernels	4675	of C<64> handles (probably owning to the fact that all windows kernels
3699	can only wait for C<64> things at the same time internally; Microsoft	4676	can only wait for C<64> things at the same time internally; Microsoft
3700	recommends spawning a chain of threads and wait for 63 handles and the	4677	recommends spawning a chain of threads and wait for 63 handles and the
3701	previous thread in each. Great).	4678	previous thread in each. Sounds great!).
3702		4679
3703	Newer versions support more handles, but you need to define C<FD_SETSIZE>	4680	Newer versions support more handles, but you need to define C<FD_SETSIZE>
3704	to some high number (e.g. C<2048>) before compiling the winsocket select	4681	to some high number (e.g. C<2048>) before compiling the winsocket select
3705	call (which might be in libev or elsewhere, for example, perl does its own	4682	call (which might be in libev or elsewhere, for example, perl and many
3706	select emulation on windows).	4683	other interpreters do their own select emulation on windows).
3707		4684
3708	Another limit is the number of file descriptors in the Microsoft runtime	4685	Another limit is the number of file descriptors in the Microsoft runtime
3709	libraries, which by default is C<64> (there must be a hidden I<64> fetish	4686	libraries, which by default is C<64> (there must be a hidden I<64>
3710	or something like this inside Microsoft). You can increase this by calling	4687	fetish or something like this inside Microsoft). You can increase this
3711	C<_setmaxstdio>, which can increase this limit to C<2048> (another	4688	by calling C<_setmaxstdio>, which can increase this limit to C<2048>
3712	arbitrary limit), but is broken in many versions of the Microsoft runtime	4689	(another arbitrary limit), but is broken in many versions of the Microsoft
3713	libraries.
3714
3715	This might get you to about C<512> or C<2048> sockets (depending on	4690	runtime libraries. This might get you to about C<512> or C<2048> sockets
3716	windows version and/or the phase of the moon). To get more, you need to	4691	(depending on windows version and/or the phase of the moon). To get more,
3717	wrap all I/O functions and provide your own fd management, but the cost of	4692	you need to wrap all I/O functions and provide your own fd management, but
3718	calling select (O(n²)) will likely make this unworkable.	4693	the cost of calling select (O(n²)) will likely make this unworkable.
3719
3720	=back
3721		4694
3722	=head2 PORTABILITY REQUIREMENTS	4695	=head2 PORTABILITY REQUIREMENTS
3723		4696
3724	In addition to a working ISO-C implementation and of course the	4697	In addition to a working ISO-C implementation and of course the
3725	backend-specific APIs, libev relies on a few additional extensions:	4698	backend-specific APIs, libev relies on a few additional extensions:
…		…
3764	watchers.	4737	watchers.
3765		4738
3766	=item C<double> must hold a time value in seconds with enough accuracy	4739	=item C<double> must hold a time value in seconds with enough accuracy
3767		4740
3768	The type C<double> is used to represent timestamps. It is required to	4741	The type C<double> is used to represent timestamps. It is required to
3769	have at least 51 bits of mantissa (and 9 bits of exponent), which is good	4742	have at least 51 bits of mantissa (and 9 bits of exponent), which is
3770	enough for at least into the year 4000. This requirement is fulfilled by	4743	good enough for at least into the year 4000 with millisecond accuracy
		4744	(the design goal for libev). This requirement is overfulfilled by
3771	implementations implementing IEEE 754 (basically all existing ones).	4745	implementations using IEEE 754, which is basically all existing ones. With
		4746	IEEE 754 doubles, you get microsecond accuracy until at least 2200.
3772		4747
3773	=back	4748	=back
3774		4749
3775	If you know of other additional requirements drop me a note.	4750	If you know of other additional requirements drop me a note.
3776		4751
…		…
3844	involves iterating over all running async watchers or all signal numbers.	4819	involves iterating over all running async watchers or all signal numbers.
3845		4820
3846	=back	4821	=back
3847		4822
3848		4823
		4824	=head1 PORTING FROM LIBEV 3.X TO 4.X
		4825
		4826	The major version 4 introduced some minor incompatible changes to the API.
		4827
		4828	At the moment, the C<ev.h> header file tries to implement superficial
		4829	compatibility, so most programs should still compile. Those might be
		4830	removed in later versions of libev, so better update early than late.
		4831
		4832	=over 4
		4833
		4834	=item function/symbol renames
		4835
		4836	A number of functions and symbols have been renamed:
		4837
		4838	ev_loop => ev_run
		4839	EVLOOP_NONBLOCK => EVRUN_NOWAIT
		4840	EVLOOP_ONESHOT => EVRUN_ONCE
		4841
		4842	ev_unloop => ev_break
		4843	EVUNLOOP_CANCEL => EVBREAK_CANCEL
		4844	EVUNLOOP_ONE => EVBREAK_ONE
		4845	EVUNLOOP_ALL => EVBREAK_ALL
		4846
		4847	EV_TIMEOUT => EV_TIMER
		4848
		4849	ev_loop_count => ev_iteration
		4850	ev_loop_depth => ev_depth
		4851	ev_loop_verify => ev_verify
		4852
		4853	Most functions working on C<struct ev_loop> objects don't have an
		4854	C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and
		4855	associated constants have been renamed to not collide with the C<struct
		4856	ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme
		4857	as all other watcher types. Note that C<ev_loop_fork> is still called
		4858	C<ev_loop_fork> because it would otherwise clash with the C<ev_fork>
		4859	typedef.
		4860
		4861	=item C<EV_COMPAT3> backwards compatibility mechanism
		4862
		4863	The backward compatibility mechanism can be controlled by
		4864	C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING>
		4865	section.
		4866
		4867	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>
		4868
		4869	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different
		4870	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile
		4871	and work, but the library code will of course be larger.
		4872
		4873	=back
		4874
		4875
		4876	=head1 GLOSSARY
		4877
		4878	=over 4
		4879
		4880	=item active
		4881
		4882	A watcher is active as long as it has been started and not yet stopped.
		4883	See L<WATCHER STATES> for details.
		4884
		4885	=item application
		4886
		4887	In this document, an application is whatever is using libev.
		4888
		4889	=item backend
		4890
		4891	The part of the code dealing with the operating system interfaces.
		4892
		4893	=item callback
		4894
		4895	The address of a function that is called when some event has been
		4896	detected. Callbacks are being passed the event loop, the watcher that
		4897	received the event, and the actual event bitset.
		4898
		4899	=item callback/watcher invocation
		4900
		4901	The act of calling the callback associated with a watcher.
		4902
		4903	=item event
		4904
		4905	A change of state of some external event, such as data now being available
		4906	for reading on a file descriptor, time having passed or simply not having
		4907	any other events happening anymore.
		4908
		4909	In libev, events are represented as single bits (such as C<EV_READ> or
		4910	C<EV_TIMER>).
		4911
		4912	=item event library
		4913
		4914	A software package implementing an event model and loop.
		4915
		4916	=item event loop
		4917
		4918	An entity that handles and processes external events and converts them
		4919	into callback invocations.
		4920
		4921	=item event model
		4922
		4923	The model used to describe how an event loop handles and processes
		4924	watchers and events.
		4925
		4926	=item pending
		4927
		4928	A watcher is pending as soon as the corresponding event has been
		4929	detected. See L<WATCHER STATES> for details.
		4930
		4931	=item real time
		4932
		4933	The physical time that is observed. It is apparently strictly monotonic :)
		4934
		4935	=item wall-clock time
		4936
		4937	The time and date as shown on clocks. Unlike real time, it can actually
		4938	be wrong and jump forwards and backwards, e.g. when the you adjust your
		4939	clock.
		4940
		4941	=item watcher
		4942
		4943	A data structure that describes interest in certain events. Watchers need
		4944	to be started (attached to an event loop) before they can receive events.
		4945
		4946	=back
		4947
3849	=head1 AUTHOR	4948	=head1 AUTHOR
3850		4949
3851	Marc Lehmann <libev@schmorp.de>.	4950	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson.
3852		4951

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