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Revision 1.309 by root, Thu Oct 21 09:23:21 2010 UTC vs.
Revision 1.351 by root, Mon Jan 10 14:24:26 2011 UTC

…		…
26	puts ("stdin ready");	26	puts ("stdin ready");
27	// for one-shot events, one must manually stop the watcher	27	// for one-shot events, one must manually stop the watcher
28	// with its corresponding stop function.	28	// with its corresponding stop function.
29	ev_io_stop (EV_A_ w);	29	ev_io_stop (EV_A_ w);
30		30
31	// this causes all nested ev_loop's to stop iterating	31	// this causes all nested ev_run's to stop iterating
32	ev_unloop (EV_A_ EVUNLOOP_ALL);	32	ev_break (EV_A_ EVBREAK_ALL);
33	}	33	}
34		34
35	// another callback, this time for a time-out	35	// another callback, this time for a time-out
36	static void	36	static void
37	timeout_cb (EV_P_ ev_timer *w, int revents)	37	timeout_cb (EV_P_ ev_timer *w, int revents)
38	{	38	{
39	puts ("timeout");	39	puts ("timeout");
40	// this causes the innermost ev_loop to stop iterating	40	// this causes the innermost ev_run to stop iterating
41	ev_unloop (EV_A_ EVUNLOOP_ONE);	41	ev_break (EV_A_ EVBREAK_ONE);
42	}	42	}
43		43
44	int	44	int
45	main (void)	45	main (void)
46	{	46	{
47	// use the default event loop unless you have special needs	47	// use the default event loop unless you have special needs
48	struct ev_loop *loop = ev_default_loop (0);	48	struct ev_loop *loop = EV_DEFAULT;
49		49
50	// initialise an io watcher, then start it	50	// initialise an io watcher, then start it
51	// this one will watch for stdin to become readable	51	// this one will watch for stdin to become readable
52	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);
53	ev_io_start (loop, &stdin_watcher);	53	ev_io_start (loop, &stdin_watcher);
…		…
56	// simple non-repeating 5.5 second timeout	56	// simple non-repeating 5.5 second timeout
57	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);	57	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
58	ev_timer_start (loop, &timeout_watcher);	58	ev_timer_start (loop, &timeout_watcher);
59		59
60	// now wait for events to arrive	60	// now wait for events to arrive
61	ev_loop (loop, 0);	61	ev_run (loop, 0);
62		62
63	// unloop was called, so exit	63	// unloop was called, so exit
64	return 0;	64	return 0;
65	}	65	}
66		66
…		…
77	on event-based programming, nor will it introduce event-based programming	77	on event-based programming, nor will it introduce event-based programming
78	with libev.	78	with libev.
79		79
80	Familiarity with event based programming techniques in general is assumed	80	Familiarity with event based programming techniques in general is assumed
81	throughout this document.	81	throughout this document.
		82
		83	=head1 WHAT TO READ WHEN IN A HURRY
		84
		85	This manual tries to be very detailed, but unfortunately, this also makes
		86	it very long. If you just want to know the basics of libev, I suggest
		87	reading L<ANATOMY OF A WATCHER>, then the L<EXAMPLE PROGRAM> above and
		88	look up the missing functions in L<GLOBAL FUNCTIONS> and the C<ev_io> and
		89	C<ev_timer> sections in L<WATCHER TYPES>.
82		90
83	=head1 ABOUT LIBEV	91	=head1 ABOUT LIBEV
84		92
85	Libev is an event loop: you register interest in certain events (such as a	93	Libev is an event loop: you register interest in certain events (such as a
86	file descriptor being readable or a timeout occurring), and it will manage	94	file descriptor being readable or a timeout occurring), and it will manage
…		…
124	this argument.	132	this argument.
125		133
126	=head2 TIME REPRESENTATION	134	=head2 TIME REPRESENTATION
127		135
128	Libev represents time as a single floating point number, representing	136	Libev represents time as a single floating point number, representing
129	the (fractional) number of seconds since the (POSIX) epoch (in practise	137	the (fractional) number of seconds since the (POSIX) epoch (in practice
130	somewhere near the beginning of 1970, details are complicated, don't	138	somewhere near the beginning of 1970, details are complicated, don't
131	ask). This type is called C<ev_tstamp>, which is what you should use	139	ask). This type is called C<ev_tstamp>, which is what you should use
132	too. It usually aliases to the C<double> type in C. When you need to do	140	too. It usually aliases to the C<double> type in C. When you need to do
133	any calculations on it, you should treat it as some floating point value.	141	any calculations on it, you should treat it as some floating point value.
134		142
…		…
165		173
166	=item ev_tstamp ev_time ()	174	=item ev_tstamp ev_time ()
167		175
168	Returns the current time as libev would use it. Please note that the	176	Returns the current time as libev would use it. Please note that the
169	C<ev_now> function is usually faster and also often returns the timestamp	177	C<ev_now> function is usually faster and also often returns the timestamp
170	you actually want to know.	178	you actually want to know. Also interesting is the combination of
		179	C<ev_update_now> and C<ev_now>.
171		180
172	=item ev_sleep (ev_tstamp interval)	181	=item ev_sleep (ev_tstamp interval)
173		182
174	Sleep for the given interval: The current thread will be blocked until	183	Sleep for the given interval: The current thread will be blocked until
175	either it is interrupted or the given time interval has passed. Basically	184	either it is interrupted or the given time interval has passed. Basically
…		…
192	as this indicates an incompatible change. Minor versions are usually	201	as this indicates an incompatible change. Minor versions are usually
193	compatible to older versions, so a larger minor version alone is usually	202	compatible to older versions, so a larger minor version alone is usually
194	not a problem.	203	not a problem.
195		204
196	Example: Make sure we haven't accidentally been linked against the wrong	205	Example: Make sure we haven't accidentally been linked against the wrong
197	version (note, however, that this will not detect ABI mismatches :).	206	version (note, however, that this will not detect other ABI mismatches,
		207	such as LFS or reentrancy).
198		208
199	assert (("libev version mismatch",	209	assert (("libev version mismatch",
200	ev_version_major () == EV_VERSION_MAJOR	210	ev_version_major () == EV_VERSION_MAJOR
201	&& ev_version_minor () >= EV_VERSION_MINOR));	211	&& ev_version_minor () >= EV_VERSION_MINOR));
202		212
…		…
213	assert (("sorry, no epoll, no sex",	223	assert (("sorry, no epoll, no sex",
214	ev_supported_backends () & EVBACKEND_EPOLL));	224	ev_supported_backends () & EVBACKEND_EPOLL));
215		225
216	=item unsigned int ev_recommended_backends ()	226	=item unsigned int ev_recommended_backends ()
217		227
218	Return the set of all backends compiled into this binary of libev and also	228	Return the set of all backends compiled into this binary of libev and
219	recommended for this platform. This set is often smaller than the one	229	also recommended for this platform, meaning it will work for most file
		230	descriptor types. This set is often smaller than the one returned by
220	returned by C<ev_supported_backends>, as for example kqueue is broken on	231	C<ev_supported_backends>, as for example kqueue is broken on most BSDs
221	most BSDs and will not be auto-detected unless you explicitly request it	232	and will not be auto-detected unless you explicitly request it (assuming
222	(assuming you know what you are doing). This is the set of backends that	233	you know what you are doing). This is the set of backends that libev will
223	libev will probe for if you specify no backends explicitly.	234	probe for if you specify no backends explicitly.
224		235
225	=item unsigned int ev_embeddable_backends ()	236	=item unsigned int ev_embeddable_backends ()
226		237
227	Returns the set of backends that are embeddable in other event loops. This	238	Returns the set of backends that are embeddable in other event loops. This
228	is the theoretical, all-platform, value. To find which backends	239	value is platform-specific but can include backends not available on the
229	might be supported on the current system, you would need to look at	240	current system. To find which embeddable backends might be supported on
230	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for	241	the current system, you would need to look at C<ev_embeddable_backends ()
231	recommended ones.	242	& ev_supported_backends ()>, likewise for recommended ones.
232		243
233	See the description of C<ev_embed> watchers for more info.	244	See the description of C<ev_embed> watchers for more info.
234		245
235	=item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT]	246	=item ev_set_allocator (void *(*cb)(void *ptr, long size))
236		247
237	Sets the allocation function to use (the prototype is similar - the	248	Sets the allocation function to use (the prototype is similar - the
238	semantics are identical to the C<realloc> C89/SuS/POSIX function). It is	249	semantics are identical to the C<realloc> C89/SuS/POSIX function). It is
239	used to allocate and free memory (no surprises here). If it returns zero	250	used to allocate and free memory (no surprises here). If it returns zero
240	when memory needs to be allocated (C<size != 0>), the library might abort	251	when memory needs to be allocated (C<size != 0>), the library might abort
…		…
266	}	277	}
267		278
268	...	279	...
269	ev_set_allocator (persistent_realloc);	280	ev_set_allocator (persistent_realloc);
270		281
271	=item ev_set_syserr_cb (void (*cb)(const char *msg)); [NOT REENTRANT]	282	=item ev_set_syserr_cb (void (*cb)(const char *msg))
272		283
273	Set the callback function to call on a retryable system call error (such	284	Set the callback function to call on a retryable system call error (such
274	as failed select, poll, epoll_wait). The message is a printable string	285	as failed select, poll, epoll_wait). The message is a printable string
275	indicating the system call or subsystem causing the problem. If this	286	indicating the system call or subsystem causing the problem. If this
276	callback is set, then libev will expect it to remedy the situation, no	287	callback is set, then libev will expect it to remedy the situation, no
…		…
288	}	299	}
289		300
290	...	301	...
291	ev_set_syserr_cb (fatal_error);	302	ev_set_syserr_cb (fatal_error);
292		303
		304	=item ev_feed_signal (int signum)
		305
		306	This function can be used to "simulate" a signal receive. It is completely
		307	safe to call this function at any time, from any context, including signal
		308	handlers or random threads.
		309
		310	Its main use is to customise signal handling in your process, especially
		311	in the presence of threads. For example, you could block signals
		312	by default in all threads (and specifying C<EVFLAG_NOSIGMASK> when
		313	creating any loops), and in one thread, use C<sigwait> or any other
		314	mechanism to wait for signals, then "deliver" them to libev by calling
		315	C<ev_feed_signal>.
		316
293	=back	317	=back
294		318
295	=head1 FUNCTIONS CONTROLLING THE EVENT LOOP	319	=head1 FUNCTIONS CONTROLLING EVENT LOOPS
296		320
297	An event loop is described by a C<struct ev_loop *> (the C<struct>	321	An event loop is described by a C<struct ev_loop *> (the C<struct> is
298	is I<not> optional in this case, as there is also an C<ev_loop>	322	I<not> optional in this case unless libev 3 compatibility is disabled, as
299	I<function>).	323	libev 3 had an C<ev_loop> function colliding with the struct name).
300		324
301	The library knows two types of such loops, the I<default> loop, which	325	The library knows two types of such loops, the I<default> loop, which
302	supports signals and child events, and dynamically created loops which do	326	supports child process events, and dynamically created event loops which
303	not.	327	do not.
304		328
305	=over 4	329	=over 4
306		330
307	=item struct ev_loop *ev_default_loop (unsigned int flags)	331	=item struct ev_loop *ev_default_loop (unsigned int flags)
308		332
309	This will initialise the default event loop if it hasn't been initialised	333	This returns the "default" event loop object, which is what you should
310	yet and return it. If the default loop could not be initialised, returns	334	normally use when you just need "the event loop". Event loop objects and
311	false. If it already was initialised it simply returns it (and ignores the	335	the C<flags> parameter are described in more detail in the entry for
312	flags. If that is troubling you, check C<ev_backend ()> afterwards).	336	C<ev_loop_new>.
		337
		338	If the default loop is already initialised then this function simply
		339	returns it (and ignores the flags. If that is troubling you, check
		340	C<ev_backend ()> afterwards). Otherwise it will create it with the given
		341	flags, which should almost always be C<0>, unless the caller is also the
		342	one calling C<ev_run> or otherwise qualifies as "the main program".
313		343
314	If you don't know what event loop to use, use the one returned from this	344	If you don't know what event loop to use, use the one returned from this
315	function.	345	function (or via the C<EV_DEFAULT> macro).
316		346
317	Note that this function is I<not> thread-safe, so if you want to use it	347	Note that this function is I<not> thread-safe, so if you want to use it
318	from multiple threads, you have to lock (note also that this is unlikely,	348	from multiple threads, you have to employ some kind of mutex (note also
319	as loops cannot be shared easily between threads anyway).	349	that this case is unlikely, as loops cannot be shared easily between
		350	threads anyway).
320		351
321	The default loop is the only loop that can handle C<ev_signal> and	352	The default loop is the only loop that can handle C<ev_child> watchers,
322	C<ev_child> watchers, and to do this, it always registers a handler	353	and to do this, it always registers a handler for C<SIGCHLD>. If this is
323	for C<SIGCHLD>. If this is a problem for your application you can either	354	a problem for your application you can either create a dynamic loop with
324	create a dynamic loop with C<ev_loop_new> that doesn't do that, or you	355	C<ev_loop_new> which doesn't do that, or you can simply overwrite the
325	can simply overwrite the C<SIGCHLD> signal handler I<after> calling	356	C<SIGCHLD> signal handler I<after> calling C<ev_default_init>.
326	C<ev_default_init>.	357
		358	Example: This is the most typical usage.
		359
		360	if (!ev_default_loop (0))
		361	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
		362
		363	Example: Restrict libev to the select and poll backends, and do not allow
		364	environment settings to be taken into account:
		365
		366	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
		367
		368	=item struct ev_loop *ev_loop_new (unsigned int flags)
		369
		370	This will create and initialise a new event loop object. If the loop
		371	could not be initialised, returns false.
		372
		373	This function is thread-safe, and one common way to use libev with
		374	threads is indeed to create one loop per thread, and using the default
		375	loop in the "main" or "initial" thread.
327		376
328	The flags argument can be used to specify special behaviour or specific	377	The flags argument can be used to specify special behaviour or specific
329	backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>).	378	backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>).
330		379
331	The following flags are supported:	380	The following flags are supported:
…		…
366	environment variable.	415	environment variable.
367		416
368	=item C<EVFLAG_NOINOTIFY>	417	=item C<EVFLAG_NOINOTIFY>
369		418
370	When this flag is specified, then libev will not attempt to use the	419	When this flag is specified, then libev will not attempt to use the
371	I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and	420	I<inotify> API for its C<ev_stat> watchers. Apart from debugging and
372	testing, this flag can be useful to conserve inotify file descriptors, as	421	testing, this flag can be useful to conserve inotify file descriptors, as
373	otherwise each loop using C<ev_stat> watchers consumes one inotify handle.	422	otherwise each loop using C<ev_stat> watchers consumes one inotify handle.
374		423
375	=item C<EVFLAG_SIGNALFD>	424	=item C<EVFLAG_SIGNALFD>
376		425
377	When this flag is specified, then libev will attempt to use the	426	When this flag is specified, then libev will attempt to use the
378	I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This API	427	I<signalfd> API for its C<ev_signal> (and C<ev_child>) watchers. This API
379	delivers signals synchronously, which makes it both faster and might make	428	delivers signals synchronously, which makes it both faster and might make
380	it possible to get the queued signal data. It can also simplify signal	429	it possible to get the queued signal data. It can also simplify signal
381	handling with threads, as long as you properly block signals in your	430	handling with threads, as long as you properly block signals in your
382	threads that are not interested in handling them.	431	threads that are not interested in handling them.
383		432
384	Signalfd will not be used by default as this changes your signal mask, and	433	Signalfd will not be used by default as this changes your signal mask, and
385	there are a lot of shoddy libraries and programs (glib's threadpool for	434	there are a lot of shoddy libraries and programs (glib's threadpool for
386	example) that can't properly initialise their signal masks.	435	example) that can't properly initialise their signal masks.
		436
		437	=item C<EVFLAG_NOSIGMASK>
		438
		439	When this flag is specified, then libev will avoid to modify the signal
		440	mask. Specifically, this means you ahve to make sure signals are unblocked
		441	when you want to receive them.
		442
		443	This behaviour is useful when you want to do your own signal handling, or
		444	want to handle signals only in specific threads and want to avoid libev
		445	unblocking the signals.
		446
		447	This flag's behaviour will become the default in future versions of libev.
387		448
388	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	449	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
389		450
390	This is your standard select(2) backend. Not I<completely> standard, as	451	This is your standard select(2) backend. Not I<completely> standard, as
391	libev tries to roll its own fd_set with no limits on the number of fds,	452	libev tries to roll its own fd_set with no limits on the number of fds,
…		…
427	epoll scales either O(1) or O(active_fds).	488	epoll scales either O(1) or O(active_fds).
428		489
429	The epoll mechanism deserves honorable mention as the most misdesigned	490	The epoll mechanism deserves honorable mention as the most misdesigned
430	of the more advanced event mechanisms: mere annoyances include silently	491	of the more advanced event mechanisms: mere annoyances include silently
431	dropping file descriptors, requiring a system call per change per file	492	dropping file descriptors, requiring a system call per change per file
432	descriptor (and unnecessary guessing of parameters), problems with dup and	493	descriptor (and unnecessary guessing of parameters), problems with dup,
		494	returning before the timeout value, resulting in additional iterations
		495	(and only giving 5ms accuracy while select on the same platform gives
433	so on. The biggest issue is fork races, however - if a program forks then	496	0.1ms) and so on. The biggest issue is fork races, however - if a program
434	I<both> parent and child process have to recreate the epoll set, which can	497	forks then I<both> parent and child process have to recreate the epoll
435	take considerable time (one syscall per file descriptor) and is of course	498	set, which can take considerable time (one syscall per file descriptor)
436	hard to detect.	499	and is of course hard to detect.
437		500
438	Epoll is also notoriously buggy - embedding epoll fds I<should> work, but	501	Epoll is also notoriously buggy - embedding epoll fds I<should> work, but
439	of course I<doesn't>, and epoll just loves to report events for totally	502	of course I<doesn't>, and epoll just loves to report events for totally
440	I<different> file descriptors (even already closed ones, so one cannot	503	I<different> file descriptors (even already closed ones, so one cannot
441	even remove them from the set) than registered in the set (especially	504	even remove them from the set) than registered in the set (especially
…		…
443	employing an additional generation counter and comparing that against the	506	employing an additional generation counter and comparing that against the
444	events to filter out spurious ones, recreating the set when required. Last	507	events to filter out spurious ones, recreating the set when required. Last
445	not least, it also refuses to work with some file descriptors which work	508	not least, it also refuses to work with some file descriptors which work
446	perfectly fine with C<select> (files, many character devices...).	509	perfectly fine with C<select> (files, many character devices...).
447		510
		511	Epoll is truly the train wreck analog among event poll mechanisms.
		512
448	While stopping, setting and starting an I/O watcher in the same iteration	513	While stopping, setting and starting an I/O watcher in the same iteration
449	will result in some caching, there is still a system call per such	514	will result in some caching, there is still a system call per such
450	incident (because the same I<file descriptor> could point to a different	515	incident (because the same I<file descriptor> could point to a different
451	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed	516	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed
452	file descriptors might not work very well if you register events for both	517	file descriptors might not work very well if you register events for both
…		…
517	=item C<EVBACKEND_PORT> (value 32, Solaris 10)	582	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
518		583
519	This uses the Solaris 10 event port mechanism. As with everything on Solaris,	584	This uses the Solaris 10 event port mechanism. As with everything on Solaris,
520	it's really slow, but it still scales very well (O(active_fds)).	585	it's really slow, but it still scales very well (O(active_fds)).
521		586
522	Please note that Solaris event ports can deliver a lot of spurious
523	notifications, so you need to use non-blocking I/O or other means to avoid
524	blocking when no data (or space) is available.
525
526	While this backend scales well, it requires one system call per active	587	While this backend scales well, it requires one system call per active
527	file descriptor per loop iteration. For small and medium numbers of file	588	file descriptor per loop iteration. For small and medium numbers of file
528	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend	589	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend
529	might perform better.	590	might perform better.
530		591
531	On the positive side, with the exception of the spurious readiness	592	On the positive side, this backend actually performed fully to
532	notifications, this backend actually performed fully to specification
533	in all tests and is fully embeddable, which is a rare feat among the	593	specification in all tests and is fully embeddable, which is a rare feat
534	OS-specific backends (I vastly prefer correctness over speed hacks).	594	among the OS-specific backends (I vastly prefer correctness over speed
		595	hacks).
		596
		597	On the negative side, the interface is I<bizarre>, with the event polling
		598	function sometimes returning events to the caller even though an error
		599	occured, but with no indication whether it has done so or not (yes, it's
		600	even documented that way) - deadly for edge-triggered interfaces, but
		601	fortunately libev seems to be able to work around it.
535		602
536	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as	603	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as
537	C<EVBACKEND_POLL>.	604	C<EVBACKEND_POLL>.
538		605
539	=item C<EVBACKEND_ALL>	606	=item C<EVBACKEND_ALL>
540		607
541	Try all backends (even potentially broken ones that wouldn't be tried	608	Try all backends (even potentially broken ones that wouldn't be tried
542	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as	609	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as
543	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.	610	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.
544		611
545	It is definitely not recommended to use this flag.	612	It is definitely not recommended to use this flag, use whatever
		613	C<ev_recommended_backends ()> returns, or simply do not specify a backend
		614	at all.
		615
		616	=item C<EVBACKEND_MASK>
		617
		618	Not a backend at all, but a mask to select all backend bits from a
		619	C<flags> value, in case you want to mask out any backends from a flags
		620	value (e.g. when modifying the C<LIBEV_FLAGS> environment variable).
546		621
547	=back	622	=back
548		623
549	If one or more of the backend flags are or'ed into the flags value,	624	If one or more of the backend flags are or'ed into the flags value,
550	then only these backends will be tried (in the reverse order as listed	625	then only these backends will be tried (in the reverse order as listed
551	here). If none are specified, all backends in C<ev_recommended_backends	626	here). If none are specified, all backends in C<ev_recommended_backends
552	()> will be tried.	627	()> will be tried.
553		628
554	Example: This is the most typical usage.
555
556	if (!ev_default_loop (0))
557	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
558
559	Example: Restrict libev to the select and poll backends, and do not allow
560	environment settings to be taken into account:
561
562	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
563
564	Example: Use whatever libev has to offer, but make sure that kqueue is
565	used if available (warning, breaks stuff, best use only with your own
566	private event loop and only if you know the OS supports your types of
567	fds):
568
569	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
570
571	=item struct ev_loop *ev_loop_new (unsigned int flags)
572
573	Similar to C<ev_default_loop>, but always creates a new event loop that is
574	always distinct from the default loop.
575
576	Note that this function I<is> thread-safe, and one common way to use
577	libev with threads is indeed to create one loop per thread, and using the
578	default loop in the "main" or "initial" thread.
579
580	Example: Try to create a event loop that uses epoll and nothing else.	629	Example: Try to create a event loop that uses epoll and nothing else.
581		630
582	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	631	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
583	if (!epoller)	632	if (!epoller)
584	fatal ("no epoll found here, maybe it hides under your chair");	633	fatal ("no epoll found here, maybe it hides under your chair");
585		634
		635	Example: Use whatever libev has to offer, but make sure that kqueue is
		636	used if available.
		637
		638	struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE);
		639
586	=item ev_default_destroy ()	640	=item ev_loop_destroy (loop)
587		641
588	Destroys the default loop (frees all memory and kernel state etc.). None	642	Destroys an event loop object (frees all memory and kernel state
589	of the active event watchers will be stopped in the normal sense, so	643	etc.). None of the active event watchers will be stopped in the normal
590	e.g. C<ev_is_active> might still return true. It is your responsibility to	644	sense, so e.g. C<ev_is_active> might still return true. It is your
591	either stop all watchers cleanly yourself I<before> calling this function,	645	responsibility to either stop all watchers cleanly yourself I<before>
592	or cope with the fact afterwards (which is usually the easiest thing, you	646	calling this function, or cope with the fact afterwards (which is usually
593	can just ignore the watchers and/or C<free ()> them for example).	647	the easiest thing, you can just ignore the watchers and/or C<free ()> them
		648	for example).
594		649
595	Note that certain global state, such as signal state (and installed signal	650	Note that certain global state, such as signal state (and installed signal
596	handlers), will not be freed by this function, and related watchers (such	651	handlers), will not be freed by this function, and related watchers (such
597	as signal and child watchers) would need to be stopped manually.	652	as signal and child watchers) would need to be stopped manually.
598		653
599	In general it is not advisable to call this function except in the	654	This function is normally used on loop objects allocated by
600	rare occasion where you really need to free e.g. the signal handling	655	C<ev_loop_new>, but it can also be used on the default loop returned by
		656	C<ev_default_loop>, in which case it is not thread-safe.
		657
		658	Note that it is not advisable to call this function on the default loop
		659	except in the rare occasion where you really need to free its resources.
601	pipe fds. If you need dynamically allocated loops it is better to use	660	If you need dynamically allocated loops it is better to use C<ev_loop_new>
602	C<ev_loop_new> and C<ev_loop_destroy>.	661	and C<ev_loop_destroy>.
603		662
604	=item ev_loop_destroy (loop)	663	=item ev_loop_fork (loop)
605		664
606	Like C<ev_default_destroy>, but destroys an event loop created by an
607	earlier call to C<ev_loop_new>.
608
609	=item ev_default_fork ()
610
611	This function sets a flag that causes subsequent C<ev_loop> iterations	665	This function sets a flag that causes subsequent C<ev_run> iterations to
612	to reinitialise the kernel state for backends that have one. Despite the	666	reinitialise the kernel state for backends that have one. Despite the
613	name, you can call it anytime, but it makes most sense after forking, in	667	name, you can call it anytime, but it makes most sense after forking, in
614	the child process (or both child and parent, but that again makes little	668	the child process. You I<must> call it (or use C<EVFLAG_FORKCHECK>) in the
615	sense). You I<must> call it in the child before using any of the libev	669	child before resuming or calling C<ev_run>.
616	functions, and it will only take effect at the next C<ev_loop> iteration.
617		670
618	Again, you I<have> to call it on I<any> loop that you want to re-use after	671	Again, you I<have> to call it on I<any> loop that you want to re-use after
619	a fork, I<even if you do not plan to use the loop in the parent>. This is	672	a fork, I<even if you do not plan to use the loop in the parent>. This is
620	because some kernel interfaces *cough* I<kqueue> *cough* do funny things	673	because some kernel interfaces *cough* I<kqueue> *cough* do funny things
621	during fork.	674	during fork.
622		675
623	On the other hand, you only need to call this function in the child	676	On the other hand, you only need to call this function in the child
624	process if and only if you want to use the event loop in the child. If you	677	process if and only if you want to use the event loop in the child. If
625	just fork+exec or create a new loop in the child, you don't have to call	678	you just fork+exec or create a new loop in the child, you don't have to
626	it at all.	679	call it at all (in fact, C<epoll> is so badly broken that it makes a
		680	difference, but libev will usually detect this case on its own and do a
		681	costly reset of the backend).
627		682
628	The function itself is quite fast and it's usually not a problem to call	683	The function itself is quite fast and it's usually not a problem to call
629	it just in case after a fork. To make this easy, the function will fit in	684	it just in case after a fork.
630	quite nicely into a call to C<pthread_atfork>:
631		685
		686	Example: Automate calling C<ev_loop_fork> on the default loop when
		687	using pthreads.
		688
		689	static void
		690	post_fork_child (void)
		691	{
		692	ev_loop_fork (EV_DEFAULT);
		693	}
		694
		695	...
632	pthread_atfork (0, 0, ev_default_fork);	696	pthread_atfork (0, 0, post_fork_child);
633
634	=item ev_loop_fork (loop)
635
636	Like C<ev_default_fork>, but acts on an event loop created by
637	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
638	after fork that you want to re-use in the child, and how you keep track of
639	them is entirely your own problem.
640		697
641	=item int ev_is_default_loop (loop)	698	=item int ev_is_default_loop (loop)
642		699
643	Returns true when the given loop is, in fact, the default loop, and false	700	Returns true when the given loop is, in fact, the default loop, and false
644	otherwise.	701	otherwise.
645		702
646	=item unsigned int ev_iteration (loop)	703	=item unsigned int ev_iteration (loop)
647		704
648	Returns the current iteration count for the loop, which is identical to	705	Returns the current iteration count for the event loop, which is identical
649	the number of times libev did poll for new events. It starts at C<0> and	706	to the number of times libev did poll for new events. It starts at C<0>
650	happily wraps around with enough iterations.	707	and happily wraps around with enough iterations.
651		708
652	This value can sometimes be useful as a generation counter of sorts (it	709	This value can sometimes be useful as a generation counter of sorts (it
653	"ticks" the number of loop iterations), as it roughly corresponds with	710	"ticks" the number of loop iterations), as it roughly corresponds with
654	C<ev_prepare> and C<ev_check> calls - and is incremented between the	711	C<ev_prepare> and C<ev_check> calls - and is incremented between the
655	prepare and check phases.	712	prepare and check phases.
656		713
657	=item unsigned int ev_depth (loop)	714	=item unsigned int ev_depth (loop)
658		715
659	Returns the number of times C<ev_loop> was entered minus the number of	716	Returns the number of times C<ev_run> was entered minus the number of
660	times C<ev_loop> was exited, in other words, the recursion depth.	717	times C<ev_run> was exited normally, in other words, the recursion depth.
661		718
662	Outside C<ev_loop>, this number is zero. In a callback, this number is	719	Outside C<ev_run>, this number is zero. In a callback, this number is
663	C<1>, unless C<ev_loop> was invoked recursively (or from another thread),	720	C<1>, unless C<ev_run> was invoked recursively (or from another thread),
664	in which case it is higher.	721	in which case it is higher.
665		722
666	Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread	723	Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread,
667	etc.), doesn't count as "exit" - consider this as a hint to avoid such	724	throwing an exception etc.), doesn't count as "exit" - consider this
668	ungentleman behaviour unless it's really convenient.	725	as a hint to avoid such ungentleman-like behaviour unless it's really
		726	convenient, in which case it is fully supported.
669		727
670	=item unsigned int ev_backend (loop)	728	=item unsigned int ev_backend (loop)
671		729
672	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	730	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
673	use.	731	use.
…		…
682		740
683	=item ev_now_update (loop)	741	=item ev_now_update (loop)
684		742
685	Establishes the current time by querying the kernel, updating the time	743	Establishes the current time by querying the kernel, updating the time
686	returned by C<ev_now ()> in the progress. This is a costly operation and	744	returned by C<ev_now ()> in the progress. This is a costly operation and
687	is usually done automatically within C<ev_loop ()>.	745	is usually done automatically within C<ev_run ()>.
688		746
689	This function is rarely useful, but when some event callback runs for a	747	This function is rarely useful, but when some event callback runs for a
690	very long time without entering the event loop, updating libev's idea of	748	very long time without entering the event loop, updating libev's idea of
691	the current time is a good idea.	749	the current time is a good idea.
692		750
…		…
694		752
695	=item ev_suspend (loop)	753	=item ev_suspend (loop)
696		754
697	=item ev_resume (loop)	755	=item ev_resume (loop)
698		756
699	These two functions suspend and resume a loop, for use when the loop is	757	These two functions suspend and resume an event loop, for use when the
700	not used for a while and timeouts should not be processed.	758	loop is not used for a while and timeouts should not be processed.
701		759
702	A typical use case would be an interactive program such as a game: When	760	A typical use case would be an interactive program such as a game: When
703	the user presses C<^Z> to suspend the game and resumes it an hour later it	761	the user presses C<^Z> to suspend the game and resumes it an hour later it
704	would be best to handle timeouts as if no time had actually passed while	762	would be best to handle timeouts as if no time had actually passed while
705	the program was suspended. This can be achieved by calling C<ev_suspend>	763	the program was suspended. This can be achieved by calling C<ev_suspend>
…		…
716	without a previous call to C<ev_suspend>.	774	without a previous call to C<ev_suspend>.
717		775
718	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the	776	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the
719	event loop time (see C<ev_now_update>).	777	event loop time (see C<ev_now_update>).
720		778
721	=item ev_loop (loop, int flags)	779	=item ev_run (loop, int flags)
722		780
723	Finally, this is it, the event handler. This function usually is called	781	Finally, this is it, the event handler. This function usually is called
724	after you have initialised all your watchers and you want to start	782	after you have initialised all your watchers and you want to start
725	handling events.	783	handling events. It will ask the operating system for any new events, call
		784	the watcher callbacks, an then repeat the whole process indefinitely: This
		785	is why event loops are called I<loops>.
726		786
727	If the flags argument is specified as C<0>, it will not return until	787	If the flags argument is specified as C<0>, it will keep handling events
728	either no event watchers are active anymore or C<ev_unloop> was called.	788	until either no event watchers are active anymore or C<ev_break> was
		789	called.
729		790
730	Please note that an explicit C<ev_unloop> is usually better than	791	Please note that an explicit C<ev_break> is usually better than
731	relying on all watchers to be stopped when deciding when a program has	792	relying on all watchers to be stopped when deciding when a program has
732	finished (especially in interactive programs), but having a program	793	finished (especially in interactive programs), but having a program
733	that automatically loops as long as it has to and no longer by virtue	794	that automatically loops as long as it has to and no longer by virtue
734	of relying on its watchers stopping correctly, that is truly a thing of	795	of relying on its watchers stopping correctly, that is truly a thing of
735	beauty.	796	beauty.
736		797
		798	This function is also I<mostly> exception-safe - you can break out of
		799	a C<ev_run> call by calling C<longjmp> in a callback, throwing a C++
		800	exception and so on. This does not decrement the C<ev_depth> value, nor
		801	will it clear any outstanding C<EVBREAK_ONE> breaks.
		802
737	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle	803	A flags value of C<EVRUN_NOWAIT> will look for new events, will handle
738	those events and any already outstanding ones, but will not block your	804	those events and any already outstanding ones, but will not wait and
739	process in case there are no events and will return after one iteration of	805	block your process in case there are no events and will return after one
740	the loop.	806	iteration of the loop. This is sometimes useful to poll and handle new
		807	events while doing lengthy calculations, to keep the program responsive.
741		808
742	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if	809	A flags value of C<EVRUN_ONCE> will look for new events (waiting if
743	necessary) and will handle those and any already outstanding ones. It	810	necessary) and will handle those and any already outstanding ones. It
744	will block your process until at least one new event arrives (which could	811	will block your process until at least one new event arrives (which could
745	be an event internal to libev itself, so there is no guarantee that a	812	be an event internal to libev itself, so there is no guarantee that a
746	user-registered callback will be called), and will return after one	813	user-registered callback will be called), and will return after one
747	iteration of the loop.	814	iteration of the loop.
748		815
749	This is useful if you are waiting for some external event in conjunction	816	This is useful if you are waiting for some external event in conjunction
750	with something not expressible using other libev watchers (i.e. "roll your	817	with something not expressible using other libev watchers (i.e. "roll your
751	own C<ev_loop>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is	818	own C<ev_run>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is
752	usually a better approach for this kind of thing.	819	usually a better approach for this kind of thing.
753		820
754	Here are the gory details of what C<ev_loop> does:	821	Here are the gory details of what C<ev_run> does:
755		822
		823	- Increment loop depth.
		824	- Reset the ev_break status.
756	- Before the first iteration, call any pending watchers.	825	- Before the first iteration, call any pending watchers.
		826	LOOP:
757	* If EVFLAG_FORKCHECK was used, check for a fork.	827	- If EVFLAG_FORKCHECK was used, check for a fork.
758	- If a fork was detected (by any means), queue and call all fork watchers.	828	- If a fork was detected (by any means), queue and call all fork watchers.
759	- Queue and call all prepare watchers.	829	- Queue and call all prepare watchers.
		830	- If ev_break was called, goto FINISH.
760	- If we have been forked, detach and recreate the kernel state	831	- If we have been forked, detach and recreate the kernel state
761	as to not disturb the other process.	832	as to not disturb the other process.
762	- Update the kernel state with all outstanding changes.	833	- Update the kernel state with all outstanding changes.
763	- Update the "event loop time" (ev_now ()).	834	- Update the "event loop time" (ev_now ()).
764	- Calculate for how long to sleep or block, if at all	835	- Calculate for how long to sleep or block, if at all
765	(active idle watchers, EVLOOP_NONBLOCK or not having	836	(active idle watchers, EVRUN_NOWAIT or not having
766	any active watchers at all will result in not sleeping).	837	any active watchers at all will result in not sleeping).
767	- Sleep if the I/O and timer collect interval say so.	838	- Sleep if the I/O and timer collect interval say so.
		839	- Increment loop iteration counter.
768	- Block the process, waiting for any events.	840	- Block the process, waiting for any events.
769	- Queue all outstanding I/O (fd) events.	841	- Queue all outstanding I/O (fd) events.
770	- Update the "event loop time" (ev_now ()), and do time jump adjustments.	842	- Update the "event loop time" (ev_now ()), and do time jump adjustments.
771	- Queue all expired timers.	843	- Queue all expired timers.
772	- Queue all expired periodics.	844	- Queue all expired periodics.
773	- Unless any events are pending now, queue all idle watchers.	845	- Queue all idle watchers with priority higher than that of pending events.
774	- Queue all check watchers.	846	- Queue all check watchers.
775	- Call all queued watchers in reverse order (i.e. check watchers first).	847	- Call all queued watchers in reverse order (i.e. check watchers first).
776	Signals and child watchers are implemented as I/O watchers, and will	848	Signals and child watchers are implemented as I/O watchers, and will
777	be handled here by queueing them when their watcher gets executed.	849	be handled here by queueing them when their watcher gets executed.
778	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	850	- If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT
779	were used, or there are no active watchers, return, otherwise	851	were used, or there are no active watchers, goto FINISH, otherwise
780	continue with step *.	852	continue with step LOOP.
		853	FINISH:
		854	- Reset the ev_break status iff it was EVBREAK_ONE.
		855	- Decrement the loop depth.
		856	- Return.
781		857
782	Example: Queue some jobs and then loop until no events are outstanding	858	Example: Queue some jobs and then loop until no events are outstanding
783	anymore.	859	anymore.
784		860
785	... queue jobs here, make sure they register event watchers as long	861	... queue jobs here, make sure they register event watchers as long
786	... as they still have work to do (even an idle watcher will do..)	862	... as they still have work to do (even an idle watcher will do..)
787	ev_loop (my_loop, 0);	863	ev_run (my_loop, 0);
788	... jobs done or somebody called unloop. yeah!	864	... jobs done or somebody called unloop. yeah!
789		865
790	=item ev_unloop (loop, how)	866	=item ev_break (loop, how)
791		867
792	Can be used to make a call to C<ev_loop> return early (but only after it	868	Can be used to make a call to C<ev_run> return early (but only after it
793	has processed all outstanding events). The C<how> argument must be either	869	has processed all outstanding events). The C<how> argument must be either
794	C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or	870	C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or
795	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.	871	C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return.
796		872
797	This "unloop state" will be cleared when entering C<ev_loop> again.	873	This "break state" will be cleared on the next call to C<ev_run>.
798		874
799	It is safe to call C<ev_unloop> from outside any C<ev_loop> calls.	875	It is safe to call C<ev_break> from outside any C<ev_run> calls, too, in
		876	which case it will have no effect.
800		877
801	=item ev_ref (loop)	878	=item ev_ref (loop)
802		879
803	=item ev_unref (loop)	880	=item ev_unref (loop)
804		881
805	Ref/unref can be used to add or remove a reference count on the event	882	Ref/unref can be used to add or remove a reference count on the event
806	loop: Every watcher keeps one reference, and as long as the reference	883	loop: Every watcher keeps one reference, and as long as the reference
807	count is nonzero, C<ev_loop> will not return on its own.	884	count is nonzero, C<ev_run> will not return on its own.
808		885
809	This is useful when you have a watcher that you never intend to	886	This is useful when you have a watcher that you never intend to
810	unregister, but that nevertheless should not keep C<ev_loop> from	887	unregister, but that nevertheless should not keep C<ev_run> from
811	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>	888	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>
812	before stopping it.	889	before stopping it.
813		890
814	As an example, libev itself uses this for its internal signal pipe: It	891	As an example, libev itself uses this for its internal signal pipe: It
815	is not visible to the libev user and should not keep C<ev_loop> from	892	is not visible to the libev user and should not keep C<ev_run> from
816	exiting if no event watchers registered by it are active. It is also an	893	exiting if no event watchers registered by it are active. It is also an
817	excellent way to do this for generic recurring timers or from within	894	excellent way to do this for generic recurring timers or from within
818	third-party libraries. Just remember to I<unref after start> and I<ref	895	third-party libraries. Just remember to I<unref after start> and I<ref
819	before stop> (but only if the watcher wasn't active before, or was active	896	before stop> (but only if the watcher wasn't active before, or was active
820	before, respectively. Note also that libev might stop watchers itself	897	before, respectively. Note also that libev might stop watchers itself
821	(e.g. non-repeating timers) in which case you have to C<ev_ref>	898	(e.g. non-repeating timers) in which case you have to C<ev_ref>
822	in the callback).	899	in the callback).
823		900
824	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	901	Example: Create a signal watcher, but keep it from keeping C<ev_run>
825	running when nothing else is active.	902	running when nothing else is active.
826		903
827	ev_signal exitsig;	904	ev_signal exitsig;
828	ev_signal_init (&exitsig, sig_cb, SIGINT);	905	ev_signal_init (&exitsig, sig_cb, SIGINT);
829	ev_signal_start (loop, &exitsig);	906	ev_signal_start (loop, &exitsig);
830	evf_unref (loop);	907	ev_unref (loop);
831		908
832	Example: For some weird reason, unregister the above signal handler again.	909	Example: For some weird reason, unregister the above signal handler again.
833		910
834	ev_ref (loop);	911	ev_ref (loop);
835	ev_signal_stop (loop, &exitsig);	912	ev_signal_stop (loop, &exitsig);
…		…
892	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);	969	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);
893		970
894	=item ev_invoke_pending (loop)	971	=item ev_invoke_pending (loop)
895		972
896	This call will simply invoke all pending watchers while resetting their	973	This call will simply invoke all pending watchers while resetting their
897	pending state. Normally, C<ev_loop> does this automatically when required,	974	pending state. Normally, C<ev_run> does this automatically when required,
898	but when overriding the invoke callback this call comes handy.	975	but when overriding the invoke callback this call comes handy. This
		976	function can be invoked from a watcher - this can be useful for example
		977	when you want to do some lengthy calculation and want to pass further
		978	event handling to another thread (you still have to make sure only one
		979	thread executes within C<ev_invoke_pending> or C<ev_run> of course).
899		980
900	=item int ev_pending_count (loop)	981	=item int ev_pending_count (loop)
901		982
902	Returns the number of pending watchers - zero indicates that no watchers	983	Returns the number of pending watchers - zero indicates that no watchers
903	are pending.	984	are pending.
904		985
905	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))	986	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))
906		987
907	This overrides the invoke pending functionality of the loop: Instead of	988	This overrides the invoke pending functionality of the loop: Instead of
908	invoking all pending watchers when there are any, C<ev_loop> will call	989	invoking all pending watchers when there are any, C<ev_run> will call
909	this callback instead. This is useful, for example, when you want to	990	this callback instead. This is useful, for example, when you want to
910	invoke the actual watchers inside another context (another thread etc.).	991	invoke the actual watchers inside another context (another thread etc.).
911		992
912	If you want to reset the callback, use C<ev_invoke_pending> as new	993	If you want to reset the callback, use C<ev_invoke_pending> as new
913	callback.	994	callback.
…		…
916		997
917	Sometimes you want to share the same loop between multiple threads. This	998	Sometimes you want to share the same loop between multiple threads. This
918	can be done relatively simply by putting mutex_lock/unlock calls around	999	can be done relatively simply by putting mutex_lock/unlock calls around
919	each call to a libev function.	1000	each call to a libev function.
920		1001
921	However, C<ev_loop> can run an indefinite time, so it is not feasible to	1002	However, C<ev_run> can run an indefinite time, so it is not feasible
922	wait for it to return. One way around this is to wake up the loop via	1003	to wait for it to return. One way around this is to wake up the event
923	C<ev_unloop> and C<av_async_send>, another way is to set these I<release>	1004	loop via C<ev_break> and C<av_async_send>, another way is to set these
924	and I<acquire> callbacks on the loop.	1005	I<release> and I<acquire> callbacks on the loop.
925		1006
926	When set, then C<release> will be called just before the thread is	1007	When set, then C<release> will be called just before the thread is
927	suspended waiting for new events, and C<acquire> is called just	1008	suspended waiting for new events, and C<acquire> is called just
928	afterwards.	1009	afterwards.
929		1010
…		…
932		1013
933	While event loop modifications are allowed between invocations of	1014	While event loop modifications are allowed between invocations of
934	C<release> and C<acquire> (that's their only purpose after all), no	1015	C<release> and C<acquire> (that's their only purpose after all), no
935	modifications done will affect the event loop, i.e. adding watchers will	1016	modifications done will affect the event loop, i.e. adding watchers will
936	have no effect on the set of file descriptors being watched, or the time	1017	have no effect on the set of file descriptors being watched, or the time
937	waited. Use an C<ev_async> watcher to wake up C<ev_loop> when you want it	1018	waited. Use an C<ev_async> watcher to wake up C<ev_run> when you want it
938	to take note of any changes you made.	1019	to take note of any changes you made.
939		1020
940	In theory, threads executing C<ev_loop> will be async-cancel safe between	1021	In theory, threads executing C<ev_run> will be async-cancel safe between
941	invocations of C<release> and C<acquire>.	1022	invocations of C<release> and C<acquire>.
942		1023
943	See also the locking example in the C<THREADS> section later in this	1024	See also the locking example in the C<THREADS> section later in this
944	document.	1025	document.
945		1026
946	=item ev_set_userdata (loop, void *data)	1027	=item ev_set_userdata (loop, void *data)
947		1028
948	=item ev_userdata (loop)	1029	=item void *ev_userdata (loop)
949		1030
950	Set and retrieve a single C<void *> associated with a loop. When	1031	Set and retrieve a single C<void *> associated with a loop. When
951	C<ev_set_userdata> has never been called, then C<ev_userdata> returns	1032	C<ev_set_userdata> has never been called, then C<ev_userdata> returns
952	C<0.>	1033	C<0>.
953		1034
954	These two functions can be used to associate arbitrary data with a loop,	1035	These two functions can be used to associate arbitrary data with a loop,
955	and are intended solely for the C<invoke_pending_cb>, C<release> and	1036	and are intended solely for the C<invoke_pending_cb>, C<release> and
956	C<acquire> callbacks described above, but of course can be (ab-)used for	1037	C<acquire> callbacks described above, but of course can be (ab-)used for
957	any other purpose as well.	1038	any other purpose as well.
…		…
975		1056
976	In the following description, uppercase C<TYPE> in names stands for the	1057	In the following description, uppercase C<TYPE> in names stands for the
977	watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer	1058	watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer
978	watchers and C<ev_io_start> for I/O watchers.	1059	watchers and C<ev_io_start> for I/O watchers.
979		1060
980	A watcher is a structure that you create and register to record your	1061	A watcher is an opaque structure that you allocate and register to record
981	interest in some event. For instance, if you want to wait for STDIN to	1062	your interest in some event. To make a concrete example, imagine you want
982	become readable, you would create an C<ev_io> watcher for that:	1063	to wait for STDIN to become readable, you would create an C<ev_io> watcher
		1064	for that:
983		1065
984	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)	1066	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)
985	{	1067	{
986	ev_io_stop (w);	1068	ev_io_stop (w);
987	ev_unloop (loop, EVUNLOOP_ALL);	1069	ev_break (loop, EVBREAK_ALL);
988	}	1070	}
989		1071
990	struct ev_loop *loop = ev_default_loop (0);	1072	struct ev_loop *loop = ev_default_loop (0);
991		1073
992	ev_io stdin_watcher;	1074	ev_io stdin_watcher;
993		1075
994	ev_init (&stdin_watcher, my_cb);	1076	ev_init (&stdin_watcher, my_cb);
995	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	1077	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
996	ev_io_start (loop, &stdin_watcher);	1078	ev_io_start (loop, &stdin_watcher);
997		1079
998	ev_loop (loop, 0);	1080	ev_run (loop, 0);
999		1081
1000	As you can see, you are responsible for allocating the memory for your	1082	As you can see, you are responsible for allocating the memory for your
1001	watcher structures (and it is I<usually> a bad idea to do this on the	1083	watcher structures (and it is I<usually> a bad idea to do this on the
1002	stack).	1084	stack).
1003		1085
1004	Each watcher has an associated watcher structure (called C<struct ev_TYPE>	1086	Each watcher has an associated watcher structure (called C<struct ev_TYPE>
1005	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).	1087	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).
1006		1088
1007	Each watcher structure must be initialised by a call to C<ev_init	1089	Each watcher structure must be initialised by a call to C<ev_init (watcher
1008	(watcher *, callback)>, which expects a callback to be provided. This	1090	*, callback)>, which expects a callback to be provided. This callback is
1009	callback gets invoked each time the event occurs (or, in the case of I/O	1091	invoked each time the event occurs (or, in the case of I/O watchers, each
1010	watchers, each time the event loop detects that the file descriptor given	1092	time the event loop detects that the file descriptor given is readable
1011	is readable and/or writable).	1093	and/or writable).
1012		1094
1013	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>	1095	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>
1014	macro to configure it, with arguments specific to the watcher type. There	1096	macro to configure it, with arguments specific to the watcher type. There
1015	is also a macro to combine initialisation and setting in one call: C<<	1097	is also a macro to combine initialisation and setting in one call: C<<
1016	ev_TYPE_init (watcher *, callback, ...) >>.	1098	ev_TYPE_init (watcher *, callback, ...) >>.
…		…
1067		1149
1068	=item C<EV_PREPARE>	1150	=item C<EV_PREPARE>
1069		1151
1070	=item C<EV_CHECK>	1152	=item C<EV_CHECK>
1071		1153
1072	All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts	1154	All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts
1073	to gather new events, and all C<ev_check> watchers are invoked just after	1155	to gather new events, and all C<ev_check> watchers are invoked just after
1074	C<ev_loop> has gathered them, but before it invokes any callbacks for any	1156	C<ev_run> has gathered them, but before it invokes any callbacks for any
1075	received events. Callbacks of both watcher types can start and stop as	1157	received events. Callbacks of both watcher types can start and stop as
1076	many watchers as they want, and all of them will be taken into account	1158	many watchers as they want, and all of them will be taken into account
1077	(for example, a C<ev_prepare> watcher might start an idle watcher to keep	1159	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
1078	C<ev_loop> from blocking).	1160	C<ev_run> from blocking).
1079		1161
1080	=item C<EV_EMBED>	1162	=item C<EV_EMBED>
1081		1163
1082	The embedded event loop specified in the C<ev_embed> watcher needs attention.	1164	The embedded event loop specified in the C<ev_embed> watcher needs attention.
1083		1165
1084	=item C<EV_FORK>	1166	=item C<EV_FORK>
1085		1167
1086	The event loop has been resumed in the child process after fork (see	1168	The event loop has been resumed in the child process after fork (see
1087	C<ev_fork>).	1169	C<ev_fork>).
		1170
		1171	=item C<EV_CLEANUP>
		1172
		1173	The event loop is about to be destroyed (see C<ev_cleanup>).
1088		1174
1089	=item C<EV_ASYNC>	1175	=item C<EV_ASYNC>
1090		1176
1091	The given async watcher has been asynchronously notified (see C<ev_async>).	1177	The given async watcher has been asynchronously notified (see C<ev_async>).
1092		1178
…		…
1264		1350
1265	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related	1351	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related
1266	functions that do not need a watcher.	1352	functions that do not need a watcher.
1267		1353
1268	=back	1354	=back
1269
1270		1355
1271	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	1356	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
1272		1357
1273	Each watcher has, by default, a member C<void *data> that you can change	1358	Each watcher has, by default, a member C<void *data> that you can change
1274	and read at any time: libev will completely ignore it. This can be used	1359	and read at any time: libev will completely ignore it. This can be used
…		…
1330	t2_cb (EV_P_ ev_timer *w, int revents)	1415	t2_cb (EV_P_ ev_timer *w, int revents)
1331	{	1416	{
1332	struct my_biggy big = (struct my_biggy *)	1417	struct my_biggy big = (struct my_biggy *)
1333	(((char *)w) - offsetof (struct my_biggy, t2));	1418	(((char *)w) - offsetof (struct my_biggy, t2));
1334	}	1419	}
		1420
		1421	=head2 WATCHER STATES
		1422
		1423	There are various watcher states mentioned throughout this manual -
		1424	active, pending and so on. In this section these states and the rules to
		1425	transition between them will be described in more detail - and while these
		1426	rules might look complicated, they usually do "the right thing".
		1427
		1428	=over 4
		1429
		1430	=item initialiased
		1431
		1432	Before a watcher can be registered with the event looop it has to be
		1433	initialised. This can be done with a call to C<ev_TYPE_init>, or calls to
		1434	C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function.
		1435
		1436	In this state it is simply some block of memory that is suitable for use
		1437	in an event loop. It can be moved around, freed, reused etc. at will.
		1438
		1439	=item started/running/active
		1440
		1441	Once a watcher has been started with a call to C<ev_TYPE_start> it becomes
		1442	property of the event loop, and is actively waiting for events. While in
		1443	this state it cannot be accessed (except in a few documented ways), moved,
		1444	freed or anything else - the only legal thing is to keep a pointer to it,
		1445	and call libev functions on it that are documented to work on active watchers.
		1446
		1447	=item pending
		1448
		1449	If a watcher is active and libev determines that an event it is interested
		1450	in has occurred (such as a timer expiring), it will become pending. It will
		1451	stay in this pending state until either it is stopped or its callback is
		1452	about to be invoked, so it is not normally pending inside the watcher
		1453	callback.
		1454
		1455	The watcher might or might not be active while it is pending (for example,
		1456	an expired non-repeating timer can be pending but no longer active). If it
		1457	is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>),
		1458	but it is still property of the event loop at this time, so cannot be
		1459	moved, freed or reused. And if it is active the rules described in the
		1460	previous item still apply.
		1461
		1462	It is also possible to feed an event on a watcher that is not active (e.g.
		1463	via C<ev_feed_event>), in which case it becomes pending without being
		1464	active.
		1465
		1466	=item stopped
		1467
		1468	A watcher can be stopped implicitly by libev (in which case it might still
		1469	be pending), or explicitly by calling its C<ev_TYPE_stop> function. The
		1470	latter will clear any pending state the watcher might be in, regardless
		1471	of whether it was active or not, so stopping a watcher explicitly before
		1472	freeing it is often a good idea.
		1473
		1474	While stopped (and not pending) the watcher is essentially in the
		1475	initialised state, that is it can be reused, moved, modified in any way
		1476	you wish.
		1477
		1478	=back
1335		1479
1336	=head2 WATCHER PRIORITY MODELS	1480	=head2 WATCHER PRIORITY MODELS
1337		1481
1338	Many event loops support I<watcher priorities>, which are usually small	1482	Many event loops support I<watcher priorities>, which are usually small
1339	integers that influence the ordering of event callback invocation	1483	integers that influence the ordering of event callback invocation
…		…
1624	...	1768	...
1625	struct ev_loop *loop = ev_default_init (0);	1769	struct ev_loop *loop = ev_default_init (0);
1626	ev_io stdin_readable;	1770	ev_io stdin_readable;
1627	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1771	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1628	ev_io_start (loop, &stdin_readable);	1772	ev_io_start (loop, &stdin_readable);
1629	ev_loop (loop, 0);	1773	ev_run (loop, 0);
1630		1774
1631		1775
1632	=head2 C<ev_timer> - relative and optionally repeating timeouts	1776	=head2 C<ev_timer> - relative and optionally repeating timeouts
1633		1777
1634	Timer watchers are simple relative timers that generate an event after a	1778	Timer watchers are simple relative timers that generate an event after a
…		…
1643	The callback is guaranteed to be invoked only I<after> its timeout has	1787	The callback is guaranteed to be invoked only I<after> its timeout has
1644	passed (not I<at>, so on systems with very low-resolution clocks this	1788	passed (not I<at>, so on systems with very low-resolution clocks this
1645	might introduce a small delay). If multiple timers become ready during the	1789	might introduce a small delay). If multiple timers become ready during the
1646	same loop iteration then the ones with earlier time-out values are invoked	1790	same loop iteration then the ones with earlier time-out values are invoked
1647	before ones of the same priority with later time-out values (but this is	1791	before ones of the same priority with later time-out values (but this is
1648	no longer true when a callback calls C<ev_loop> recursively).	1792	no longer true when a callback calls C<ev_run> recursively).
1649		1793
1650	=head3 Be smart about timeouts	1794	=head3 Be smart about timeouts
1651		1795
1652	Many real-world problems involve some kind of timeout, usually for error	1796	Many real-world problems involve some kind of timeout, usually for error
1653	recovery. A typical example is an HTTP request - if the other side hangs,	1797	recovery. A typical example is an HTTP request - if the other side hangs,
…		…
1824		1968
1825	=head3 The special problem of time updates	1969	=head3 The special problem of time updates
1826		1970
1827	Establishing the current time is a costly operation (it usually takes at	1971	Establishing the current time is a costly operation (it usually takes at
1828	least two system calls): EV therefore updates its idea of the current	1972	least two system calls): EV therefore updates its idea of the current
1829	time only before and after C<ev_loop> collects new events, which causes a	1973	time only before and after C<ev_run> collects new events, which causes a
1830	growing difference between C<ev_now ()> and C<ev_time ()> when handling	1974	growing difference between C<ev_now ()> and C<ev_time ()> when handling
1831	lots of events in one iteration.	1975	lots of events in one iteration.
1832		1976
1833	The relative timeouts are calculated relative to the C<ev_now ()>	1977	The relative timeouts are calculated relative to the C<ev_now ()>
1834	time. This is usually the right thing as this timestamp refers to the time	1978	time. This is usually the right thing as this timestamp refers to the time
…		…
1951	}	2095	}
1952		2096
1953	ev_timer mytimer;	2097	ev_timer mytimer;
1954	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	2098	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1955	ev_timer_again (&mytimer); /* start timer */	2099	ev_timer_again (&mytimer); /* start timer */
1956	ev_loop (loop, 0);	2100	ev_run (loop, 0);
1957		2101
1958	// and in some piece of code that gets executed on any "activity":	2102	// and in some piece of code that gets executed on any "activity":
1959	// reset the timeout to start ticking again at 10 seconds	2103	// reset the timeout to start ticking again at 10 seconds
1960	ev_timer_again (&mytimer);	2104	ev_timer_again (&mytimer);
1961		2105
…		…
1987		2131
1988	As with timers, the callback is guaranteed to be invoked only when the	2132	As with timers, the callback is guaranteed to be invoked only when the
1989	point in time where it is supposed to trigger has passed. If multiple	2133	point in time where it is supposed to trigger has passed. If multiple
1990	timers become ready during the same loop iteration then the ones with	2134	timers become ready during the same loop iteration then the ones with
1991	earlier time-out values are invoked before ones with later time-out values	2135	earlier time-out values are invoked before ones with later time-out values
1992	(but this is no longer true when a callback calls C<ev_loop> recursively).	2136	(but this is no longer true when a callback calls C<ev_run> recursively).
1993		2137
1994	=head3 Watcher-Specific Functions and Data Members	2138	=head3 Watcher-Specific Functions and Data Members
1995		2139
1996	=over 4	2140	=over 4
1997		2141
…		…
2158		2302
2159	=head2 C<ev_signal> - signal me when a signal gets signalled!	2303	=head2 C<ev_signal> - signal me when a signal gets signalled!
2160		2304
2161	Signal watchers will trigger an event when the process receives a specific	2305	Signal watchers will trigger an event when the process receives a specific
2162	signal one or more times. Even though signals are very asynchronous, libev	2306	signal one or more times. Even though signals are very asynchronous, libev
2163	will try it's best to deliver signals synchronously, i.e. as part of the	2307	will try its best to deliver signals synchronously, i.e. as part of the
2164	normal event processing, like any other event.	2308	normal event processing, like any other event.
2165		2309
2166	If you want signals to be delivered truly asynchronously, just use	2310	If you want signals to be delivered truly asynchronously, just use
2167	C<sigaction> as you would do without libev and forget about sharing	2311	C<sigaction> as you would do without libev and forget about sharing
2168	the signal. You can even use C<ev_async> from a signal handler to	2312	the signal. You can even use C<ev_async> from a signal handler to
…		…
2211		2355
2212	So I can't stress this enough: I<If you do not reset your signal mask when	2356	So I can't stress this enough: I<If you do not reset your signal mask when
2213	you expect it to be empty, you have a race condition in your code>. This	2357	you expect it to be empty, you have a race condition in your code>. This
2214	is not a libev-specific thing, this is true for most event libraries.	2358	is not a libev-specific thing, this is true for most event libraries.
2215		2359
		2360	=head3 The special problem of threads signal handling
		2361
		2362	POSIX threads has problematic signal handling semantics, specifically,
		2363	a lot of functionality (sigfd, sigwait etc.) only really works if all
		2364	threads in a process block signals, which is hard to achieve.
		2365
		2366	When you want to use sigwait (or mix libev signal handling with your own
		2367	for the same signals), you can tackle this problem by globally blocking
		2368	all signals before creating any threads (or creating them with a fully set
		2369	sigprocmask) and also specifying the C<EVFLAG_NOSIGMASK> when creating
		2370	loops. Then designate one thread as "signal receiver thread" which handles
		2371	these signals. You can pass on any signals that libev might be interested
		2372	in by calling C<ev_feed_signal>.
		2373
2216	=head3 Watcher-Specific Functions and Data Members	2374	=head3 Watcher-Specific Functions and Data Members
2217		2375
2218	=over 4	2376	=over 4
2219		2377
2220	=item ev_signal_init (ev_signal *, callback, int signum)	2378	=item ev_signal_init (ev_signal *, callback, int signum)
…		…
2235	Example: Try to exit cleanly on SIGINT.	2393	Example: Try to exit cleanly on SIGINT.
2236		2394
2237	static void	2395	static void
2238	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)	2396	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)
2239	{	2397	{
2240	ev_unloop (loop, EVUNLOOP_ALL);	2398	ev_break (loop, EVBREAK_ALL);
2241	}	2399	}
2242		2400
2243	ev_signal signal_watcher;	2401	ev_signal signal_watcher;
2244	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	2402	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
2245	ev_signal_start (loop, &signal_watcher);	2403	ev_signal_start (loop, &signal_watcher);
…		…
2631		2789
2632	Prepare and check watchers are usually (but not always) used in pairs:	2790	Prepare and check watchers are usually (but not always) used in pairs:
2633	prepare watchers get invoked before the process blocks and check watchers	2791	prepare watchers get invoked before the process blocks and check watchers
2634	afterwards.	2792	afterwards.
2635		2793
2636	You I<must not> call C<ev_loop> or similar functions that enter	2794	You I<must not> call C<ev_run> or similar functions that enter
2637	the current event loop from either C<ev_prepare> or C<ev_check>	2795	the current event loop from either C<ev_prepare> or C<ev_check>
2638	watchers. Other loops than the current one are fine, however. The	2796	watchers. Other loops than the current one are fine, however. The
2639	rationale behind this is that you do not need to check for recursion in	2797	rationale behind this is that you do not need to check for recursion in
2640	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,	2798	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,
2641	C<ev_check> so if you have one watcher of each kind they will always be	2799	C<ev_check> so if you have one watcher of each kind they will always be
…		…
2809		2967
2810	if (timeout >= 0)	2968	if (timeout >= 0)
2811	// create/start timer	2969	// create/start timer
2812		2970
2813	// poll	2971	// poll
2814	ev_loop (EV_A_ 0);	2972	ev_run (EV_A_ 0);
2815		2973
2816	// stop timer again	2974	// stop timer again
2817	if (timeout >= 0)	2975	if (timeout >= 0)
2818	ev_timer_stop (EV_A_ &to);	2976	ev_timer_stop (EV_A_ &to);
2819		2977
…		…
2897	if you do not want that, you need to temporarily stop the embed watcher).	3055	if you do not want that, you need to temporarily stop the embed watcher).
2898		3056
2899	=item ev_embed_sweep (loop, ev_embed *)	3057	=item ev_embed_sweep (loop, ev_embed *)
2900		3058
2901	Make a single, non-blocking sweep over the embedded loop. This works	3059	Make a single, non-blocking sweep over the embedded loop. This works
2902	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	3060	similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most
2903	appropriate way for embedded loops.	3061	appropriate way for embedded loops.
2904		3062
2905	=item struct ev_loop *other [read-only]	3063	=item struct ev_loop *other [read-only]
2906		3064
2907	The embedded event loop.	3065	The embedded event loop.
…		…
2993	disadvantage of having to use multiple event loops (which do not support	3151	disadvantage of having to use multiple event loops (which do not support
2994	signal watchers).	3152	signal watchers).
2995		3153
2996	When this is not possible, or you want to use the default loop for	3154	When this is not possible, or you want to use the default loop for
2997	other reasons, then in the process that wants to start "fresh", call	3155	other reasons, then in the process that wants to start "fresh", call
2998	C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying	3156	C<ev_loop_destroy (EV_DEFAULT)> followed by C<ev_default_loop (...)>.
2999	the default loop will "orphan" (not stop) all registered watchers, so you	3157	Destroying the default loop will "orphan" (not stop) all registered
3000	have to be careful not to execute code that modifies those watchers. Note	3158	watchers, so you have to be careful not to execute code that modifies
3001	also that in that case, you have to re-register any signal watchers.	3159	those watchers. Note also that in that case, you have to re-register any
		3160	signal watchers.
3002		3161
3003	=head3 Watcher-Specific Functions and Data Members	3162	=head3 Watcher-Specific Functions and Data Members
3004		3163
3005	=over 4	3164	=over 4
3006		3165
3007	=item ev_fork_init (ev_signal *, callback)	3166	=item ev_fork_init (ev_fork *, callback)
3008		3167
3009	Initialises and configures the fork watcher - it has no parameters of any	3168	Initialises and configures the fork watcher - it has no parameters of any
3010	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,	3169	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
3011	believe me.	3170	really.
3012		3171
3013	=back	3172	=back
3014		3173
3015		3174
		3175	=head2 C<ev_cleanup> - even the best things end
		3176
		3177	Cleanup watchers are called just before the event loop is being destroyed
		3178	by a call to C<ev_loop_destroy>.
		3179
		3180	While there is no guarantee that the event loop gets destroyed, cleanup
		3181	watchers provide a convenient method to install cleanup hooks for your
		3182	program, worker threads and so on - you just to make sure to destroy the
		3183	loop when you want them to be invoked.
		3184
		3185	Cleanup watchers are invoked in the same way as any other watcher. Unlike
		3186	all other watchers, they do not keep a reference to the event loop (which
		3187	makes a lot of sense if you think about it). Like all other watchers, you
		3188	can call libev functions in the callback, except C<ev_cleanup_start>.
		3189
		3190	=head3 Watcher-Specific Functions and Data Members
		3191
		3192	=over 4
		3193
		3194	=item ev_cleanup_init (ev_cleanup *, callback)
		3195
		3196	Initialises and configures the cleanup watcher - it has no parameters of
		3197	any kind. There is a C<ev_cleanup_set> macro, but using it is utterly
		3198	pointless, I assure you.
		3199
		3200	=back
		3201
		3202	Example: Register an atexit handler to destroy the default loop, so any
		3203	cleanup functions are called.
		3204
		3205	static void
		3206	program_exits (void)
		3207	{
		3208	ev_loop_destroy (EV_DEFAULT_UC);
		3209	}
		3210
		3211	...
		3212	atexit (program_exits);
		3213
		3214
3016	=head2 C<ev_async> - how to wake up an event loop	3215	=head2 C<ev_async> - how to wake up an event loop
3017		3216
3018	In general, you cannot use an C<ev_loop> from multiple threads or other	3217	In general, you cannot use an C<ev_run> from multiple threads or other
3019	asynchronous sources such as signal handlers (as opposed to multiple event	3218	asynchronous sources such as signal handlers (as opposed to multiple event
3020	loops - those are of course safe to use in different threads).	3219	loops - those are of course safe to use in different threads).
3021		3220
3022	Sometimes, however, you need to wake up an event loop you do not control,	3221	Sometimes, however, you need to wake up an event loop you do not control,
3023	for example because it belongs to another thread. This is what C<ev_async>	3222	for example because it belongs to another thread. This is what C<ev_async>
…		…
3025	it by calling C<ev_async_send>, which is thread- and signal safe.	3224	it by calling C<ev_async_send>, which is thread- and signal safe.
3026		3225
3027	This functionality is very similar to C<ev_signal> watchers, as signals,	3226	This functionality is very similar to C<ev_signal> watchers, as signals,
3028	too, are asynchronous in nature, and signals, too, will be compressed	3227	too, are asynchronous in nature, and signals, too, will be compressed
3029	(i.e. the number of callback invocations may be less than the number of	3228	(i.e. the number of callback invocations may be less than the number of
3030	C<ev_async_sent> calls).	3229	C<ev_async_sent> calls). In fact, you could use signal watchers as a kind
		3230	of "global async watchers" by using a watcher on an otherwise unused
		3231	signal, and C<ev_feed_signal> to signal this watcher from another thread,
		3232	even without knowing which loop owns the signal.
3031		3233
3032	Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not	3234	Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not
3033	just the default loop.	3235	just the default loop.
3034		3236
3035	=head3 Queueing	3237	=head3 Queueing
…		…
3211	Feed an event on the given fd, as if a file descriptor backend detected	3413	Feed an event on the given fd, as if a file descriptor backend detected
3212	the given events it.	3414	the given events it.
3213		3415
3214	=item ev_feed_signal_event (loop, int signum)	3416	=item ev_feed_signal_event (loop, int signum)
3215		3417
3216	Feed an event as if the given signal occurred (C<loop> must be the default	3418	Feed an event as if the given signal occurred. See also C<ev_feed_signal>,
3217	loop!).	3419	which is async-safe.
		3420
		3421	=back
		3422
		3423
		3424	=head1 COMMON OR USEFUL IDIOMS (OR BOTH)
		3425
		3426	This section explains some common idioms that are not immediately
		3427	obvious. Note that examples are sprinkled over the whole manual, and this
		3428	section only contains stuff that wouldn't fit anywhere else.
		3429
		3430	=over 4
		3431
		3432	=item Model/nested event loop invocations and exit conditions.
		3433
		3434	Often (especially in GUI toolkits) there are places where you have
		3435	I<modal> interaction, which is most easily implemented by recursively
		3436	invoking C<ev_run>.
		3437
		3438	This brings the problem of exiting - a callback might want to finish the
		3439	main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but
		3440	a modal "Are you sure?" dialog is still waiting), or just the nested one
		3441	and not the main one (e.g. user clocked "Ok" in a modal dialog), or some
		3442	other combination: In these cases, C<ev_break> will not work alone.
		3443
		3444	The solution is to maintain "break this loop" variable for each C<ev_run>
		3445	invocation, and use a loop around C<ev_run> until the condition is
		3446	triggered, using C<EVRUN_ONCE>:
		3447
		3448	// main loop
		3449	int exit_main_loop = 0;
		3450
		3451	while (!exit_main_loop)
		3452	ev_run (EV_DEFAULT_ EVRUN_ONCE);
		3453
		3454	// in a model watcher
		3455	int exit_nested_loop = 0;
		3456
		3457	while (!exit_nested_loop)
		3458	ev_run (EV_A_ EVRUN_ONCE);
		3459
		3460	To exit from any of these loops, just set the corresponding exit variable:
		3461
		3462	// exit modal loop
		3463	exit_nested_loop = 1;
		3464
		3465	// exit main program, after modal loop is finished
		3466	exit_main_loop = 1;
		3467
		3468	// exit both
		3469	exit_main_loop = exit_nested_loop = 1;
3218		3470
3219	=back	3471	=back
3220		3472
3221		3473
3222	=head1 LIBEVENT EMULATION	3474	=head1 LIBEVENT EMULATION
3223		3475
3224	Libev offers a compatibility emulation layer for libevent. It cannot	3476	Libev offers a compatibility emulation layer for libevent. It cannot
3225	emulate the internals of libevent, so here are some usage hints:	3477	emulate the internals of libevent, so here are some usage hints:
3226		3478
3227	=over 4	3479	=over 4
		3480
		3481	=item * Only the libevent-1.4.1-beta API is being emulated.
		3482
		3483	This was the newest libevent version available when libev was implemented,
		3484	and is still mostly unchanged in 2010.
3228		3485
3229	=item * Use it by including <event.h>, as usual.	3486	=item * Use it by including <event.h>, as usual.
3230		3487
3231	=item * The following members are fully supported: ev_base, ev_callback,	3488	=item * The following members are fully supported: ev_base, ev_callback,
3232	ev_arg, ev_fd, ev_res, ev_events.	3489	ev_arg, ev_fd, ev_res, ev_events.
…		…
3238	=item * Priorities are not currently supported. Initialising priorities	3495	=item * Priorities are not currently supported. Initialising priorities
3239	will fail and all watchers will have the same priority, even though there	3496	will fail and all watchers will have the same priority, even though there
3240	is an ev_pri field.	3497	is an ev_pri field.
3241		3498
3242	=item * In libevent, the last base created gets the signals, in libev, the	3499	=item * In libevent, the last base created gets the signals, in libev, the
3243	first base created (== the default loop) gets the signals.	3500	base that registered the signal gets the signals.
3244		3501
3245	=item * Other members are not supported.	3502	=item * Other members are not supported.
3246		3503
3247	=item * The libev emulation is I<not> ABI compatible to libevent, you need	3504	=item * The libev emulation is I<not> ABI compatible to libevent, you need
3248	to use the libev header file and library.	3505	to use the libev header file and library.
…		…
3267	Care has been taken to keep the overhead low. The only data member the C++	3524	Care has been taken to keep the overhead low. The only data member the C++
3268	classes add (compared to plain C-style watchers) is the event loop pointer	3525	classes add (compared to plain C-style watchers) is the event loop pointer
3269	that the watcher is associated with (or no additional members at all if	3526	that the watcher is associated with (or no additional members at all if
3270	you disable C<EV_MULTIPLICITY> when embedding libev).	3527	you disable C<EV_MULTIPLICITY> when embedding libev).
3271		3528
3272	Currently, functions, and static and non-static member functions can be	3529	Currently, functions, static and non-static member functions and classes
3273	used as callbacks. Other types should be easy to add as long as they only	3530	with C<operator ()> can be used as callbacks. Other types should be easy
3274	need one additional pointer for context. If you need support for other	3531	to add as long as they only need one additional pointer for context. If
3275	types of functors please contact the author (preferably after implementing	3532	you need support for other types of functors please contact the author
3276	it).	3533	(preferably after implementing it).
3277		3534
3278	Here is a list of things available in the C<ev> namespace:	3535	Here is a list of things available in the C<ev> namespace:
3279		3536
3280	=over 4	3537	=over 4
3281		3538
…		…
3530	loop argument"). The C<EV_A> form is used when this is the sole argument,	3787	loop argument"). The C<EV_A> form is used when this is the sole argument,
3531	C<EV_A_> is used when other arguments are following. Example:	3788	C<EV_A_> is used when other arguments are following. Example:
3532		3789
3533	ev_unref (EV_A);	3790	ev_unref (EV_A);
3534	ev_timer_add (EV_A_ watcher);	3791	ev_timer_add (EV_A_ watcher);
3535	ev_loop (EV_A_ 0);	3792	ev_run (EV_A_ 0);
3536		3793
3537	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	3794	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
3538	which is often provided by the following macro.	3795	which is often provided by the following macro.
3539		3796
3540	=item C<EV_P>, C<EV_P_>	3797	=item C<EV_P>, C<EV_P_>
…		…
3580	}	3837	}
3581		3838
3582	ev_check check;	3839	ev_check check;
3583	ev_check_init (&check, check_cb);	3840	ev_check_init (&check, check_cb);
3584	ev_check_start (EV_DEFAULT_ &check);	3841	ev_check_start (EV_DEFAULT_ &check);
3585	ev_loop (EV_DEFAULT_ 0);	3842	ev_run (EV_DEFAULT_ 0);
3586		3843
3587	=head1 EMBEDDING	3844	=head1 EMBEDDING
3588		3845
3589	Libev can (and often is) directly embedded into host	3846	Libev can (and often is) directly embedded into host
3590	applications. Examples of applications that embed it include the Deliantra	3847	applications. Examples of applications that embed it include the Deliantra
…		…
3681	to a compiled library. All other symbols change the ABI, which means all	3938	to a compiled library. All other symbols change the ABI, which means all
3682	users of libev and the libev code itself must be compiled with compatible	3939	users of libev and the libev code itself must be compiled with compatible
3683	settings.	3940	settings.
3684		3941
3685	=over 4	3942	=over 4
		3943
		3944	=item EV_COMPAT3 (h)
		3945
		3946	Backwards compatibility is a major concern for libev. This is why this
		3947	release of libev comes with wrappers for the functions and symbols that
		3948	have been renamed between libev version 3 and 4.
		3949
		3950	You can disable these wrappers (to test compatibility with future
		3951	versions) by defining C<EV_COMPAT3> to C<0> when compiling your
		3952	sources. This has the additional advantage that you can drop the C<struct>
		3953	from C<struct ev_loop> declarations, as libev will provide an C<ev_loop>
		3954	typedef in that case.
		3955
		3956	In some future version, the default for C<EV_COMPAT3> will become C<0>,
		3957	and in some even more future version the compatibility code will be
		3958	removed completely.
3686		3959
3687	=item EV_STANDALONE (h)	3960	=item EV_STANDALONE (h)
3688		3961
3689	Must always be C<1> if you do not use autoconf configuration, which	3962	Must always be C<1> if you do not use autoconf configuration, which
3690	keeps libev from including F<config.h>, and it also defines dummy	3963	keeps libev from including F<config.h>, and it also defines dummy
…		…
4265	userdata *u = ev_userdata (EV_A);	4538	userdata *u = ev_userdata (EV_A);
4266	pthread_mutex_lock (&u->lock);	4539	pthread_mutex_lock (&u->lock);
4267	}	4540	}
4268		4541
4269	The event loop thread first acquires the mutex, and then jumps straight	4542	The event loop thread first acquires the mutex, and then jumps straight
4270	into C<ev_loop>:	4543	into C<ev_run>:
4271		4544
4272	void *	4545	void *
4273	l_run (void *thr_arg)	4546	l_run (void *thr_arg)
4274	{	4547	{
4275	struct ev_loop *loop = (struct ev_loop *)thr_arg;	4548	struct ev_loop *loop = (struct ev_loop *)thr_arg;
4276		4549
4277	l_acquire (EV_A);	4550	l_acquire (EV_A);
4278	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);	4551	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
4279	ev_loop (EV_A_ 0);	4552	ev_run (EV_A_ 0);
4280	l_release (EV_A);	4553	l_release (EV_A);
4281		4554
4282	return 0;	4555	return 0;
4283	}	4556	}
4284		4557
…		…
4336		4609
4337	=head3 COROUTINES	4610	=head3 COROUTINES
4338		4611
4339	Libev is very accommodating to coroutines ("cooperative threads"):	4612	Libev is very accommodating to coroutines ("cooperative threads"):
4340	libev fully supports nesting calls to its functions from different	4613	libev fully supports nesting calls to its functions from different
4341	coroutines (e.g. you can call C<ev_loop> on the same loop from two	4614	coroutines (e.g. you can call C<ev_run> on the same loop from two
4342	different coroutines, and switch freely between both coroutines running	4615	different coroutines, and switch freely between both coroutines running
4343	the loop, as long as you don't confuse yourself). The only exception is	4616	the loop, as long as you don't confuse yourself). The only exception is
4344	that you must not do this from C<ev_periodic> reschedule callbacks.	4617	that you must not do this from C<ev_periodic> reschedule callbacks.
4345		4618
4346	Care has been taken to ensure that libev does not keep local state inside	4619	Care has been taken to ensure that libev does not keep local state inside
4347	C<ev_loop>, and other calls do not usually allow for coroutine switches as	4620	C<ev_run>, and other calls do not usually allow for coroutine switches as
4348	they do not call any callbacks.	4621	they do not call any callbacks.
4349		4622
4350	=head2 COMPILER WARNINGS	4623	=head2 COMPILER WARNINGS
4351		4624
4352	Depending on your compiler and compiler settings, you might get no or a	4625	Depending on your compiler and compiler settings, you might get no or a
…		…
4436	=head3 C<kqueue> is buggy	4709	=head3 C<kqueue> is buggy
4437		4710
4438	The kqueue syscall is broken in all known versions - most versions support	4711	The kqueue syscall is broken in all known versions - most versions support
4439	only sockets, many support pipes.	4712	only sockets, many support pipes.
4440		4713
4441	Libev tries to work around this by not using C<kqueue> by default on	4714	Libev tries to work around this by not using C<kqueue> by default on this
4442	this rotten platform, but of course you can still ask for it when creating	4715	rotten platform, but of course you can still ask for it when creating a
4443	a loop.	4716	loop - embedding a socket-only kqueue loop into a select-based one is
		4717	probably going to work well.
4444		4718
4445	=head3 C<poll> is buggy	4719	=head3 C<poll> is buggy
4446		4720
4447	Instead of fixing C<kqueue>, Apple replaced their (working) C<poll>	4721	Instead of fixing C<kqueue>, Apple replaced their (working) C<poll>
4448	implementation by something calling C<kqueue> internally around the 10.5.6	4722	implementation by something calling C<kqueue> internally around the 10.5.6
…		…
4467		4741
4468	=head3 C<errno> reentrancy	4742	=head3 C<errno> reentrancy
4469		4743
4470	The default compile environment on Solaris is unfortunately so	4744	The default compile environment on Solaris is unfortunately so
4471	thread-unsafe that you can't even use components/libraries compiled	4745	thread-unsafe that you can't even use components/libraries compiled
4472	without C<-D_REENTRANT> (as long as they use C<errno>), which, of course,	4746	without C<-D_REENTRANT> in a threaded program, which, of course, isn't
4473	isn't defined by default.	4747	defined by default. A valid, if stupid, implementation choice.
4474		4748
4475	If you want to use libev in threaded environments you have to make sure	4749	If you want to use libev in threaded environments you have to make sure
4476	it's compiled with C<_REENTRANT> defined.	4750	it's compiled with C<_REENTRANT> defined.
4477		4751
4478	=head3 Event port backend	4752	=head3 Event port backend
4479		4753
4480	The scalable event interface for Solaris is called "event ports". Unfortunately,	4754	The scalable event interface for Solaris is called "event
4481	this mechanism is very buggy. If you run into high CPU usage, your program	4755	ports". Unfortunately, this mechanism is very buggy in all major
		4756	releases. If you run into high CPU usage, your program freezes or you get
4482	freezes or you get a large number of spurious wakeups, make sure you have	4757	a large number of spurious wakeups, make sure you have all the relevant
4483	all the relevant and latest kernel patches applied. No, I don't know which	4758	and latest kernel patches applied. No, I don't know which ones, but there
4484	ones, but there are multiple ones.	4759	are multiple ones to apply, and afterwards, event ports actually work
		4760	great.
4485		4761
4486	If you can't get it to work, you can try running the program by setting	4762	If you can't get it to work, you can try running the program by setting
4487	the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and	4763	the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and
4488	C<select> backends.	4764	C<select> backends.
4489		4765
4490	=head2 AIX POLL BUG	4766	=head2 AIX POLL BUG
4491		4767
4492	AIX unfortunately has a broken C<poll.h> header. Libev works around	4768	AIX unfortunately has a broken C<poll.h> header. Libev works around
4493	this by trying to avoid the poll backend altogether (i.e. it's not even	4769	this by trying to avoid the poll backend altogether (i.e. it's not even
4494	compiled in), which normally isn't a big problem as C<select> works fine	4770	compiled in), which normally isn't a big problem as C<select> works fine
4495	with large bitsets, and AIX is dead anyway.	4771	with large bitsets on AIX, and AIX is dead anyway.
4496		4772
4497	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS	4773	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
4498		4774
4499	=head3 General issues	4775	=head3 General issues
4500		4776
…		…
4606	structure (guaranteed by POSIX but not by ISO C for example), but it also	4882	structure (guaranteed by POSIX but not by ISO C for example), but it also
4607	assumes that the same (machine) code can be used to call any watcher	4883	assumes that the same (machine) code can be used to call any watcher
4608	callback: The watcher callbacks have different type signatures, but libev	4884	callback: The watcher callbacks have different type signatures, but libev
4609	calls them using an C<ev_watcher *> internally.	4885	calls them using an C<ev_watcher *> internally.
4610		4886
		4887	=item pointer accesses must be thread-atomic
		4888
		4889	Accessing a pointer value must be atomic, it must both be readable and
		4890	writable in one piece - this is the case on all current architectures.
		4891
4611	=item C<sig_atomic_t volatile> must be thread-atomic as well	4892	=item C<sig_atomic_t volatile> must be thread-atomic as well
4612		4893
4613	The type C<sig_atomic_t volatile> (or whatever is defined as	4894	The type C<sig_atomic_t volatile> (or whatever is defined as
4614	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different	4895	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different
4615	threads. This is not part of the specification for C<sig_atomic_t>, but is	4896	threads. This is not part of the specification for C<sig_atomic_t>, but is
…		…
4721	=back	5002	=back
4722		5003
4723		5004
4724	=head1 PORTING FROM LIBEV 3.X TO 4.X	5005	=head1 PORTING FROM LIBEV 3.X TO 4.X
4725		5006
4726	The major version 4 introduced some minor incompatible changes to the API.	5007	The major version 4 introduced some incompatible changes to the API.
4727		5008
4728	At the moment, the C<ev.h> header file tries to implement superficial	5009	At the moment, the C<ev.h> header file provides compatibility definitions
4729	compatibility, so most programs should still compile. Those might be	5010	for all changes, so most programs should still compile. The compatibility
4730	removed in later versions of libev, so better update early than late.	5011	layer might be removed in later versions of libev, so better update to the
		5012	new API early than late.
4731		5013
4732	=over 4	5014	=over 4
4733		5015
4734	=item C<ev_loop_count> renamed to C<ev_iteration>	5016	=item C<EV_COMPAT3> backwards compatibility mechanism
4735		5017
4736	=item C<ev_loop_depth> renamed to C<ev_depth>	5018	The backward compatibility mechanism can be controlled by
		5019	C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING>
		5020	section.
4737		5021
4738	=item C<ev_loop_verify> renamed to C<ev_verify>	5022	=item C<ev_default_destroy> and C<ev_default_fork> have been removed
		5023
		5024	These calls can be replaced easily by their C<ev_loop_xxx> counterparts:
		5025
		5026	ev_loop_destroy (EV_DEFAULT_UC);
		5027	ev_loop_fork (EV_DEFAULT);
		5028
		5029	=item function/symbol renames
		5030
		5031	A number of functions and symbols have been renamed:
		5032
		5033	ev_loop => ev_run
		5034	EVLOOP_NONBLOCK => EVRUN_NOWAIT
		5035	EVLOOP_ONESHOT => EVRUN_ONCE
		5036
		5037	ev_unloop => ev_break
		5038	EVUNLOOP_CANCEL => EVBREAK_CANCEL
		5039	EVUNLOOP_ONE => EVBREAK_ONE
		5040	EVUNLOOP_ALL => EVBREAK_ALL
		5041
		5042	EV_TIMEOUT => EV_TIMER
		5043
		5044	ev_loop_count => ev_iteration
		5045	ev_loop_depth => ev_depth
		5046	ev_loop_verify => ev_verify
4739		5047
4740	Most functions working on C<struct ev_loop> objects don't have an	5048	Most functions working on C<struct ev_loop> objects don't have an
4741	C<ev_loop_> prefix, so it was removed. Note that C<ev_loop_fork> is	5049	C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and
		5050	associated constants have been renamed to not collide with the C<struct
		5051	ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme
		5052	as all other watcher types. Note that C<ev_loop_fork> is still called
4742	still called C<ev_loop_fork> because it would otherwise clash with the	5053	C<ev_loop_fork> because it would otherwise clash with the C<ev_fork>
4743	C<ev_fork> typedef.	5054	typedef.
4744
4745	=item C<EV_TIMEOUT> renamed to C<EV_TIMER> in C<revents>
4746
4747	This is a simple rename - all other watcher types use their name
4748	as revents flag, and now C<ev_timer> does, too.
4749
4750	Both C<EV_TIMER> and C<EV_TIMEOUT> symbols were present in 3.x versions
4751	and continue to be present for the foreseeable future, so this is mostly a
4752	documentation change.
4753		5055
4754	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>	5056	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>
4755		5057
4756	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different	5058	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different
4757	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile	5059	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile
…		…
4764		5066
4765	=over 4	5067	=over 4
4766		5068
4767	=item active	5069	=item active
4768		5070
4769	A watcher is active as long as it has been started (has been attached to	5071	A watcher is active as long as it has been started and not yet stopped.
4770	an event loop) but not yet stopped (disassociated from the event loop).	5072	See L<WATCHER STATES> for details.
4771		5073
4772	=item application	5074	=item application
4773		5075
4774	In this document, an application is whatever is using libev.	5076	In this document, an application is whatever is using libev.
		5077
		5078	=item backend
		5079
		5080	The part of the code dealing with the operating system interfaces.
4775		5081
4776	=item callback	5082	=item callback
4777		5083
4778	The address of a function that is called when some event has been	5084	The address of a function that is called when some event has been
4779	detected. Callbacks are being passed the event loop, the watcher that	5085	detected. Callbacks are being passed the event loop, the watcher that
4780	received the event, and the actual event bitset.	5086	received the event, and the actual event bitset.
4781		5087
4782	=item callback invocation	5088	=item callback/watcher invocation
4783		5089
4784	The act of calling the callback associated with a watcher.	5090	The act of calling the callback associated with a watcher.
4785		5091
4786	=item event	5092	=item event
4787		5093
…		…
4806	The model used to describe how an event loop handles and processes	5112	The model used to describe how an event loop handles and processes
4807	watchers and events.	5113	watchers and events.
4808		5114
4809	=item pending	5115	=item pending
4810		5116
4811	A watcher is pending as soon as the corresponding event has been detected,	5117	A watcher is pending as soon as the corresponding event has been
4812	and stops being pending as soon as the watcher will be invoked or its	5118	detected. See L<WATCHER STATES> for details.
4813	pending status is explicitly cleared by the application.
4814
4815	A watcher can be pending, but not active. Stopping a watcher also clears
4816	its pending status.
4817		5119
4818	=item real time	5120	=item real time
4819		5121
4820	The physical time that is observed. It is apparently strictly monotonic :)	5122	The physical time that is observed. It is apparently strictly monotonic :)
4821		5123
…		…
4828	=item watcher	5130	=item watcher
4829		5131
4830	A data structure that describes interest in certain events. Watchers need	5132	A data structure that describes interest in certain events. Watchers need
4831	to be started (attached to an event loop) before they can receive events.	5133	to be started (attached to an event loop) before they can receive events.
4832		5134
4833	=item watcher invocation
4834
4835	The act of calling the callback associated with a watcher.
4836
4837	=back	5135	=back
4838		5136
4839	=head1 AUTHOR	5137	=head1 AUTHOR
4840		5138
4841	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson.	5139	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael
		5140	Magnusson and Emanuele Giaquinta.
4842		5141

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