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Revision 1.296 by root, Tue Jun 29 10:51:18 2010 UTC vs.
Revision 1.354 by root, Tue Jan 11 01:40:25 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
…		…
75	While this document tries to be as complete as possible in documenting	75	While this document tries to be as complete as possible in documenting
76	libev, its usage and the rationale behind its design, it is not a tutorial	76	libev, its usage and the rationale behind its design, it is not a tutorial
77	on event-based programming, nor will it introduce event-based programming	77	on event-based programming, nor will it introduce event-based programming
78	with libev.	78	with libev.
79		79
80	Familarity 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
442	on SMP systems). Libev tries to counter these spurious notifications by	505	on SMP systems). Libev tries to counter these spurious notifications by
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.	507	events to filter out spurious ones, recreating the set when required. Last
		508	not least, it also refuses to work with some file descriptors which work
		509	perfectly fine with C<select> (files, many character devices...).
		510
		511	Epoll is truly the train wreck analog among event poll mechanisms,
		512	a frankenpoll, cobbled together in a hurry, no thought to design or
		513	interaction with others.
445		514
446	While stopping, setting and starting an I/O watcher in the same iteration	515	While stopping, setting and starting an I/O watcher in the same iteration
447	will result in some caching, there is still a system call per such	516	will result in some caching, there is still a system call per such
448	incident (because the same I<file descriptor> could point to a different	517	incident (because the same I<file descriptor> could point to a different
449	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed	518	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed
…		…
515	=item C<EVBACKEND_PORT> (value 32, Solaris 10)	584	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
516		585
517	This uses the Solaris 10 event port mechanism. As with everything on Solaris,	586	This uses the Solaris 10 event port mechanism. As with everything on Solaris,
518	it's really slow, but it still scales very well (O(active_fds)).	587	it's really slow, but it still scales very well (O(active_fds)).
519		588
520	Please note that Solaris event ports can deliver a lot of spurious
521	notifications, so you need to use non-blocking I/O or other means to avoid
522	blocking when no data (or space) is available.
523
524	While this backend scales well, it requires one system call per active	589	While this backend scales well, it requires one system call per active
525	file descriptor per loop iteration. For small and medium numbers of file	590	file descriptor per loop iteration. For small and medium numbers of file
526	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend	591	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend
527	might perform better.	592	might perform better.
528		593
529	On the positive side, with the exception of the spurious readiness	594	On the positive side, this backend actually performed fully to
530	notifications, this backend actually performed fully to specification
531	in all tests and is fully embeddable, which is a rare feat among the	595	specification in all tests and is fully embeddable, which is a rare feat
532	OS-specific backends (I vastly prefer correctness over speed hacks).	596	among the OS-specific backends (I vastly prefer correctness over speed
		597	hacks).
		598
		599	On the negative side, the interface is I<bizarre> - so bizarre that
		600	even sun itself gets it wrong in their code examples: The event polling
		601	function sometimes returning events to the caller even though an error
		602	occurred, but with no indication whether it has done so or not (yes, it's
		603	even documented that way) - deadly for edge-triggered interfaces where
		604	you absolutely have to know whether an event occurred or not because you
		605	have to re-arm the watcher.
		606
		607	Fortunately libev seems to be able to work around these idiocies.
533		608
534	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as	609	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as
535	C<EVBACKEND_POLL>.	610	C<EVBACKEND_POLL>.
536		611
537	=item C<EVBACKEND_ALL>	612	=item C<EVBACKEND_ALL>
538		613
539	Try all backends (even potentially broken ones that wouldn't be tried	614	Try all backends (even potentially broken ones that wouldn't be tried
540	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as	615	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as
541	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.	616	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.
542		617
543	It is definitely not recommended to use this flag.	618	It is definitely not recommended to use this flag, use whatever
		619	C<ev_recommended_backends ()> returns, or simply do not specify a backend
		620	at all.
		621
		622	=item C<EVBACKEND_MASK>
		623
		624	Not a backend at all, but a mask to select all backend bits from a
		625	C<flags> value, in case you want to mask out any backends from a flags
		626	value (e.g. when modifying the C<LIBEV_FLAGS> environment variable).
544		627
545	=back	628	=back
546		629
547	If one or more of the backend flags are or'ed into the flags value,	630	If one or more of the backend flags are or'ed into the flags value,
548	then only these backends will be tried (in the reverse order as listed	631	then only these backends will be tried (in the reverse order as listed
549	here). If none are specified, all backends in C<ev_recommended_backends	632	here). If none are specified, all backends in C<ev_recommended_backends
550	()> will be tried.	633	()> will be tried.
551		634
552	Example: This is the most typical usage.
553
554	if (!ev_default_loop (0))
555	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
556
557	Example: Restrict libev to the select and poll backends, and do not allow
558	environment settings to be taken into account:
559
560	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
561
562	Example: Use whatever libev has to offer, but make sure that kqueue is
563	used if available (warning, breaks stuff, best use only with your own
564	private event loop and only if you know the OS supports your types of
565	fds):
566
567	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
568
569	=item struct ev_loop *ev_loop_new (unsigned int flags)
570
571	Similar to C<ev_default_loop>, but always creates a new event loop that is
572	always distinct from the default loop.
573
574	Note that this function I<is> thread-safe, and one common way to use
575	libev with threads is indeed to create one loop per thread, and using the
576	default loop in the "main" or "initial" thread.
577
578	Example: Try to create a event loop that uses epoll and nothing else.	635	Example: Try to create a event loop that uses epoll and nothing else.
579		636
580	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	637	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
581	if (!epoller)	638	if (!epoller)
582	fatal ("no epoll found here, maybe it hides under your chair");	639	fatal ("no epoll found here, maybe it hides under your chair");
583		640
		641	Example: Use whatever libev has to offer, but make sure that kqueue is
		642	used if available.
		643
		644	struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE);
		645
584	=item ev_default_destroy ()	646	=item ev_loop_destroy (loop)
585		647
586	Destroys the default loop (frees all memory and kernel state etc.). None	648	Destroys an event loop object (frees all memory and kernel state
587	of the active event watchers will be stopped in the normal sense, so	649	etc.). None of the active event watchers will be stopped in the normal
588	e.g. C<ev_is_active> might still return true. It is your responsibility to	650	sense, so e.g. C<ev_is_active> might still return true. It is your
589	either stop all watchers cleanly yourself I<before> calling this function,	651	responsibility to either stop all watchers cleanly yourself I<before>
590	or cope with the fact afterwards (which is usually the easiest thing, you	652	calling this function, or cope with the fact afterwards (which is usually
591	can just ignore the watchers and/or C<free ()> them for example).	653	the easiest thing, you can just ignore the watchers and/or C<free ()> them
		654	for example).
592		655
593	Note that certain global state, such as signal state (and installed signal	656	Note that certain global state, such as signal state (and installed signal
594	handlers), will not be freed by this function, and related watchers (such	657	handlers), will not be freed by this function, and related watchers (such
595	as signal and child watchers) would need to be stopped manually.	658	as signal and child watchers) would need to be stopped manually.
596		659
597	In general it is not advisable to call this function except in the	660	This function is normally used on loop objects allocated by
598	rare occasion where you really need to free e.g. the signal handling	661	C<ev_loop_new>, but it can also be used on the default loop returned by
		662	C<ev_default_loop>, in which case it is not thread-safe.
		663
		664	Note that it is not advisable to call this function on the default loop
		665	except in the rare occasion where you really need to free its resources.
599	pipe fds. If you need dynamically allocated loops it is better to use	666	If you need dynamically allocated loops it is better to use C<ev_loop_new>
600	C<ev_loop_new> and C<ev_loop_destroy>.	667	and C<ev_loop_destroy>.
601		668
602	=item ev_loop_destroy (loop)	669	=item ev_loop_fork (loop)
603		670
604	Like C<ev_default_destroy>, but destroys an event loop created by an
605	earlier call to C<ev_loop_new>.
606
607	=item ev_default_fork ()
608
609	This function sets a flag that causes subsequent C<ev_loop> iterations	671	This function sets a flag that causes subsequent C<ev_run> iterations to
610	to reinitialise the kernel state for backends that have one. Despite the	672	reinitialise the kernel state for backends that have one. Despite the
611	name, you can call it anytime, but it makes most sense after forking, in	673	name, you can call it anytime, but it makes most sense after forking, in
612	the child process (or both child and parent, but that again makes little	674	the child process. You I<must> call it (or use C<EVFLAG_FORKCHECK>) in the
613	sense). You I<must> call it in the child before using any of the libev	675	child before resuming or calling C<ev_run>.
614	functions, and it will only take effect at the next C<ev_loop> iteration.
615		676
616	Again, you I<have> to call it on I<any> loop that you want to re-use after	677	Again, you I<have> to call it on I<any> loop that you want to re-use after
617	a fork, I<even if you do not plan to use the loop in the parent>. This is	678	a fork, I<even if you do not plan to use the loop in the parent>. This is
618	because some kernel interfaces *cough* I<kqueue> *cough* do funny things	679	because some kernel interfaces *cough* I<kqueue> *cough* do funny things
619	during fork.	680	during fork.
620		681
621	On the other hand, you only need to call this function in the child	682	On the other hand, you only need to call this function in the child
622	process if and only if you want to use the event loop in the child. If you	683	process if and only if you want to use the event loop in the child. If
623	just fork+exec or create a new loop in the child, you don't have to call	684	you just fork+exec or create a new loop in the child, you don't have to
624	it at all.	685	call it at all (in fact, C<epoll> is so badly broken that it makes a
		686	difference, but libev will usually detect this case on its own and do a
		687	costly reset of the backend).
625		688
626	The function itself is quite fast and it's usually not a problem to call	689	The function itself is quite fast and it's usually not a problem to call
627	it just in case after a fork. To make this easy, the function will fit in	690	it just in case after a fork.
628	quite nicely into a call to C<pthread_atfork>:
629		691
		692	Example: Automate calling C<ev_loop_fork> on the default loop when
		693	using pthreads.
		694
		695	static void
		696	post_fork_child (void)
		697	{
		698	ev_loop_fork (EV_DEFAULT);
		699	}
		700
		701	...
630	pthread_atfork (0, 0, ev_default_fork);	702	pthread_atfork (0, 0, post_fork_child);
631
632	=item ev_loop_fork (loop)
633
634	Like C<ev_default_fork>, but acts on an event loop created by
635	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
636	after fork that you want to re-use in the child, and how you keep track of
637	them is entirely your own problem.
638		703
639	=item int ev_is_default_loop (loop)	704	=item int ev_is_default_loop (loop)
640		705
641	Returns true when the given loop is, in fact, the default loop, and false	706	Returns true when the given loop is, in fact, the default loop, and false
642	otherwise.	707	otherwise.
643		708
644	=item unsigned int ev_iteration (loop)	709	=item unsigned int ev_iteration (loop)
645		710
646	Returns the current iteration count for the loop, which is identical to	711	Returns the current iteration count for the event loop, which is identical
647	the number of times libev did poll for new events. It starts at C<0> and	712	to the number of times libev did poll for new events. It starts at C<0>
648	happily wraps around with enough iterations.	713	and happily wraps around with enough iterations.
649		714
650	This value can sometimes be useful as a generation counter of sorts (it	715	This value can sometimes be useful as a generation counter of sorts (it
651	"ticks" the number of loop iterations), as it roughly corresponds with	716	"ticks" the number of loop iterations), as it roughly corresponds with
652	C<ev_prepare> and C<ev_check> calls - and is incremented between the	717	C<ev_prepare> and C<ev_check> calls - and is incremented between the
653	prepare and check phases.	718	prepare and check phases.
654		719
655	=item unsigned int ev_depth (loop)	720	=item unsigned int ev_depth (loop)
656		721
657	Returns the number of times C<ev_loop> was entered minus the number of	722	Returns the number of times C<ev_run> was entered minus the number of
658	times C<ev_loop> was exited, in other words, the recursion depth.	723	times C<ev_run> was exited normally, in other words, the recursion depth.
659		724
660	Outside C<ev_loop>, this number is zero. In a callback, this number is	725	Outside C<ev_run>, this number is zero. In a callback, this number is
661	C<1>, unless C<ev_loop> was invoked recursively (or from another thread),	726	C<1>, unless C<ev_run> was invoked recursively (or from another thread),
662	in which case it is higher.	727	in which case it is higher.
663		728
664	Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread	729	Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread,
665	etc.), doesn't count as "exit" - consider this as a hint to avoid such	730	throwing an exception etc.), doesn't count as "exit" - consider this
666	ungentleman behaviour unless it's really convenient.	731	as a hint to avoid such ungentleman-like behaviour unless it's really
		732	convenient, in which case it is fully supported.
667		733
668	=item unsigned int ev_backend (loop)	734	=item unsigned int ev_backend (loop)
669		735
670	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	736	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
671	use.	737	use.
…		…
680		746
681	=item ev_now_update (loop)	747	=item ev_now_update (loop)
682		748
683	Establishes the current time by querying the kernel, updating the time	749	Establishes the current time by querying the kernel, updating the time
684	returned by C<ev_now ()> in the progress. This is a costly operation and	750	returned by C<ev_now ()> in the progress. This is a costly operation and
685	is usually done automatically within C<ev_loop ()>.	751	is usually done automatically within C<ev_run ()>.
686		752
687	This function is rarely useful, but when some event callback runs for a	753	This function is rarely useful, but when some event callback runs for a
688	very long time without entering the event loop, updating libev's idea of	754	very long time without entering the event loop, updating libev's idea of
689	the current time is a good idea.	755	the current time is a good idea.
690		756
…		…
692		758
693	=item ev_suspend (loop)	759	=item ev_suspend (loop)
694		760
695	=item ev_resume (loop)	761	=item ev_resume (loop)
696		762
697	These two functions suspend and resume a loop, for use when the loop is	763	These two functions suspend and resume an event loop, for use when the
698	not used for a while and timeouts should not be processed.	764	loop is not used for a while and timeouts should not be processed.
699		765
700	A typical use case would be an interactive program such as a game: When	766	A typical use case would be an interactive program such as a game: When
701	the user presses C<^Z> to suspend the game and resumes it an hour later it	767	the user presses C<^Z> to suspend the game and resumes it an hour later it
702	would be best to handle timeouts as if no time had actually passed while	768	would be best to handle timeouts as if no time had actually passed while
703	the program was suspended. This can be achieved by calling C<ev_suspend>	769	the program was suspended. This can be achieved by calling C<ev_suspend>
…		…
705	C<ev_resume> directly afterwards to resume timer processing.	771	C<ev_resume> directly afterwards to resume timer processing.
706		772
707	Effectively, all C<ev_timer> watchers will be delayed by the time spend	773	Effectively, all C<ev_timer> watchers will be delayed by the time spend
708	between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers	774	between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers
709	will be rescheduled (that is, they will lose any events that would have	775	will be rescheduled (that is, they will lose any events that would have
710	occured while suspended).	776	occurred while suspended).
711		777
712	After calling C<ev_suspend> you B<must not> call I<any> function on the	778	After calling C<ev_suspend> you B<must not> call I<any> function on the
713	given loop other than C<ev_resume>, and you B<must not> call C<ev_resume>	779	given loop other than C<ev_resume>, and you B<must not> call C<ev_resume>
714	without a previous call to C<ev_suspend>.	780	without a previous call to C<ev_suspend>.
715		781
716	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the	782	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the
717	event loop time (see C<ev_now_update>).	783	event loop time (see C<ev_now_update>).
718		784
719	=item ev_loop (loop, int flags)	785	=item ev_run (loop, int flags)
720		786
721	Finally, this is it, the event handler. This function usually is called	787	Finally, this is it, the event handler. This function usually is called
722	after you have initialised all your watchers and you want to start	788	after you have initialised all your watchers and you want to start
723	handling events.	789	handling events. It will ask the operating system for any new events, call
		790	the watcher callbacks, an then repeat the whole process indefinitely: This
		791	is why event loops are called I<loops>.
724		792
725	If the flags argument is specified as C<0>, it will not return until	793	If the flags argument is specified as C<0>, it will keep handling events
726	either no event watchers are active anymore or C<ev_unloop> was called.	794	until either no event watchers are active anymore or C<ev_break> was
		795	called.
727		796
728	Please note that an explicit C<ev_unloop> is usually better than	797	Please note that an explicit C<ev_break> is usually better than
729	relying on all watchers to be stopped when deciding when a program has	798	relying on all watchers to be stopped when deciding when a program has
730	finished (especially in interactive programs), but having a program	799	finished (especially in interactive programs), but having a program
731	that automatically loops as long as it has to and no longer by virtue	800	that automatically loops as long as it has to and no longer by virtue
732	of relying on its watchers stopping correctly, that is truly a thing of	801	of relying on its watchers stopping correctly, that is truly a thing of
733	beauty.	802	beauty.
734		803
		804	This function is also I<mostly> exception-safe - you can break out of
		805	a C<ev_run> call by calling C<longjmp> in a callback, throwing a C++
		806	exception and so on. This does not decrement the C<ev_depth> value, nor
		807	will it clear any outstanding C<EVBREAK_ONE> breaks.
		808
735	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle	809	A flags value of C<EVRUN_NOWAIT> will look for new events, will handle
736	those events and any already outstanding ones, but will not block your	810	those events and any already outstanding ones, but will not wait and
737	process in case there are no events and will return after one iteration of	811	block your process in case there are no events and will return after one
738	the loop.	812	iteration of the loop. This is sometimes useful to poll and handle new
		813	events while doing lengthy calculations, to keep the program responsive.
739		814
740	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if	815	A flags value of C<EVRUN_ONCE> will look for new events (waiting if
741	necessary) and will handle those and any already outstanding ones. It	816	necessary) and will handle those and any already outstanding ones. It
742	will block your process until at least one new event arrives (which could	817	will block your process until at least one new event arrives (which could
743	be an event internal to libev itself, so there is no guarantee that a	818	be an event internal to libev itself, so there is no guarantee that a
744	user-registered callback will be called), and will return after one	819	user-registered callback will be called), and will return after one
745	iteration of the loop.	820	iteration of the loop.
746		821
747	This is useful if you are waiting for some external event in conjunction	822	This is useful if you are waiting for some external event in conjunction
748	with something not expressible using other libev watchers (i.e. "roll your	823	with something not expressible using other libev watchers (i.e. "roll your
749	own C<ev_loop>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is	824	own C<ev_run>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is
750	usually a better approach for this kind of thing.	825	usually a better approach for this kind of thing.
751		826
752	Here are the gory details of what C<ev_loop> does:	827	Here are the gory details of what C<ev_run> does:
753		828
		829	- Increment loop depth.
		830	- Reset the ev_break status.
754	- Before the first iteration, call any pending watchers.	831	- Before the first iteration, call any pending watchers.
		832	LOOP:
755	* If EVFLAG_FORKCHECK was used, check for a fork.	833	- If EVFLAG_FORKCHECK was used, check for a fork.
756	- If a fork was detected (by any means), queue and call all fork watchers.	834	- If a fork was detected (by any means), queue and call all fork watchers.
757	- Queue and call all prepare watchers.	835	- Queue and call all prepare watchers.
		836	- If ev_break was called, goto FINISH.
758	- If we have been forked, detach and recreate the kernel state	837	- If we have been forked, detach and recreate the kernel state
759	as to not disturb the other process.	838	as to not disturb the other process.
760	- Update the kernel state with all outstanding changes.	839	- Update the kernel state with all outstanding changes.
761	- Update the "event loop time" (ev_now ()).	840	- Update the "event loop time" (ev_now ()).
762	- Calculate for how long to sleep or block, if at all	841	- Calculate for how long to sleep or block, if at all
763	(active idle watchers, EVLOOP_NONBLOCK or not having	842	(active idle watchers, EVRUN_NOWAIT or not having
764	any active watchers at all will result in not sleeping).	843	any active watchers at all will result in not sleeping).
765	- Sleep if the I/O and timer collect interval say so.	844	- Sleep if the I/O and timer collect interval say so.
		845	- Increment loop iteration counter.
766	- Block the process, waiting for any events.	846	- Block the process, waiting for any events.
767	- Queue all outstanding I/O (fd) events.	847	- Queue all outstanding I/O (fd) events.
768	- Update the "event loop time" (ev_now ()), and do time jump adjustments.	848	- Update the "event loop time" (ev_now ()), and do time jump adjustments.
769	- Queue all expired timers.	849	- Queue all expired timers.
770	- Queue all expired periodics.	850	- Queue all expired periodics.
771	- Unless any events are pending now, queue all idle watchers.	851	- Queue all idle watchers with priority higher than that of pending events.
772	- Queue all check watchers.	852	- Queue all check watchers.
773	- Call all queued watchers in reverse order (i.e. check watchers first).	853	- Call all queued watchers in reverse order (i.e. check watchers first).
774	Signals and child watchers are implemented as I/O watchers, and will	854	Signals and child watchers are implemented as I/O watchers, and will
775	be handled here by queueing them when their watcher gets executed.	855	be handled here by queueing them when their watcher gets executed.
776	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	856	- If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT
777	were used, or there are no active watchers, return, otherwise	857	were used, or there are no active watchers, goto FINISH, otherwise
778	continue with step *.	858	continue with step LOOP.
		859	FINISH:
		860	- Reset the ev_break status iff it was EVBREAK_ONE.
		861	- Decrement the loop depth.
		862	- Return.
779		863
780	Example: Queue some jobs and then loop until no events are outstanding	864	Example: Queue some jobs and then loop until no events are outstanding
781	anymore.	865	anymore.
782		866
783	... queue jobs here, make sure they register event watchers as long	867	... queue jobs here, make sure they register event watchers as long
784	... as they still have work to do (even an idle watcher will do..)	868	... as they still have work to do (even an idle watcher will do..)
785	ev_loop (my_loop, 0);	869	ev_run (my_loop, 0);
786	... jobs done or somebody called unloop. yeah!	870	... jobs done or somebody called unloop. yeah!
787		871
788	=item ev_unloop (loop, how)	872	=item ev_break (loop, how)
789		873
790	Can be used to make a call to C<ev_loop> return early (but only after it	874	Can be used to make a call to C<ev_run> return early (but only after it
791	has processed all outstanding events). The C<how> argument must be either	875	has processed all outstanding events). The C<how> argument must be either
792	C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or	876	C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or
793	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.	877	C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return.
794		878
795	This "unloop state" will be cleared when entering C<ev_loop> again.	879	This "break state" will be cleared on the next call to C<ev_run>.
796		880
797	It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls.	881	It is safe to call C<ev_break> from outside any C<ev_run> calls, too, in
		882	which case it will have no effect.
798		883
799	=item ev_ref (loop)	884	=item ev_ref (loop)
800		885
801	=item ev_unref (loop)	886	=item ev_unref (loop)
802		887
803	Ref/unref can be used to add or remove a reference count on the event	888	Ref/unref can be used to add or remove a reference count on the event
804	loop: Every watcher keeps one reference, and as long as the reference	889	loop: Every watcher keeps one reference, and as long as the reference
805	count is nonzero, C<ev_loop> will not return on its own.	890	count is nonzero, C<ev_run> will not return on its own.
806		891
807	This is useful when you have a watcher that you never intend to	892	This is useful when you have a watcher that you never intend to
808	unregister, but that nevertheless should not keep C<ev_loop> from	893	unregister, but that nevertheless should not keep C<ev_run> from
809	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>	894	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>
810	before stopping it.	895	before stopping it.
811		896
812	As an example, libev itself uses this for its internal signal pipe: It	897	As an example, libev itself uses this for its internal signal pipe: It
813	is not visible to the libev user and should not keep C<ev_loop> from	898	is not visible to the libev user and should not keep C<ev_run> from
814	exiting if no event watchers registered by it are active. It is also an	899	exiting if no event watchers registered by it are active. It is also an
815	excellent way to do this for generic recurring timers or from within	900	excellent way to do this for generic recurring timers or from within
816	third-party libraries. Just remember to I<unref after start> and I<ref	901	third-party libraries. Just remember to I<unref after start> and I<ref
817	before stop> (but only if the watcher wasn't active before, or was active	902	before stop> (but only if the watcher wasn't active before, or was active
818	before, respectively. Note also that libev might stop watchers itself	903	before, respectively. Note also that libev might stop watchers itself
819	(e.g. non-repeating timers) in which case you have to C<ev_ref>	904	(e.g. non-repeating timers) in which case you have to C<ev_ref>
820	in the callback).	905	in the callback).
821		906
822	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	907	Example: Create a signal watcher, but keep it from keeping C<ev_run>
823	running when nothing else is active.	908	running when nothing else is active.
824		909
825	ev_signal exitsig;	910	ev_signal exitsig;
826	ev_signal_init (&exitsig, sig_cb, SIGINT);	911	ev_signal_init (&exitsig, sig_cb, SIGINT);
827	ev_signal_start (loop, &exitsig);	912	ev_signal_start (loop, &exitsig);
828	evf_unref (loop);	913	ev_unref (loop);
829		914
830	Example: For some weird reason, unregister the above signal handler again.	915	Example: For some weird reason, unregister the above signal handler again.
831		916
832	ev_ref (loop);	917	ev_ref (loop);
833	ev_signal_stop (loop, &exitsig);	918	ev_signal_stop (loop, &exitsig);
…		…
872	usually doesn't make much sense to set it to a lower value than C<0.01>,	957	usually doesn't make much sense to set it to a lower value than C<0.01>,
873	as this approaches the timing granularity of most systems. Note that if	958	as this approaches the timing granularity of most systems. Note that if
874	you do transactions with the outside world and you can't increase the	959	you do transactions with the outside world and you can't increase the
875	parallelity, then this setting will limit your transaction rate (if you	960	parallelity, then this setting will limit your transaction rate (if you
876	need to poll once per transaction and the I/O collect interval is 0.01,	961	need to poll once per transaction and the I/O collect interval is 0.01,
877	then you can't do more than 100 transations per second).	962	then you can't do more than 100 transactions per second).
878		963
879	Setting the I<timeout collect interval> can improve the opportunity for	964	Setting the I<timeout collect interval> can improve the opportunity for
880	saving power, as the program will "bundle" timer callback invocations that	965	saving power, as the program will "bundle" timer callback invocations that
881	are "near" in time together, by delaying some, thus reducing the number of	966	are "near" in time together, by delaying some, thus reducing the number of
882	times the process sleeps and wakes up again. Another useful technique to	967	times the process sleeps and wakes up again. Another useful technique to
…		…
890	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);	975	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);
891		976
892	=item ev_invoke_pending (loop)	977	=item ev_invoke_pending (loop)
893		978
894	This call will simply invoke all pending watchers while resetting their	979	This call will simply invoke all pending watchers while resetting their
895	pending state. Normally, C<ev_loop> does this automatically when required,	980	pending state. Normally, C<ev_run> does this automatically when required,
896	but when overriding the invoke callback this call comes handy.	981	but when overriding the invoke callback this call comes handy. This
		982	function can be invoked from a watcher - this can be useful for example
		983	when you want to do some lengthy calculation and want to pass further
		984	event handling to another thread (you still have to make sure only one
		985	thread executes within C<ev_invoke_pending> or C<ev_run> of course).
897		986
898	=item int ev_pending_count (loop)	987	=item int ev_pending_count (loop)
899		988
900	Returns the number of pending watchers - zero indicates that no watchers	989	Returns the number of pending watchers - zero indicates that no watchers
901	are pending.	990	are pending.
902		991
903	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))	992	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))
904		993
905	This overrides the invoke pending functionality of the loop: Instead of	994	This overrides the invoke pending functionality of the loop: Instead of
906	invoking all pending watchers when there are any, C<ev_loop> will call	995	invoking all pending watchers when there are any, C<ev_run> will call
907	this callback instead. This is useful, for example, when you want to	996	this callback instead. This is useful, for example, when you want to
908	invoke the actual watchers inside another context (another thread etc.).	997	invoke the actual watchers inside another context (another thread etc.).
909		998
910	If you want to reset the callback, use C<ev_invoke_pending> as new	999	If you want to reset the callback, use C<ev_invoke_pending> as new
911	callback.	1000	callback.
…		…
914		1003
915	Sometimes you want to share the same loop between multiple threads. This	1004	Sometimes you want to share the same loop between multiple threads. This
916	can be done relatively simply by putting mutex_lock/unlock calls around	1005	can be done relatively simply by putting mutex_lock/unlock calls around
917	each call to a libev function.	1006	each call to a libev function.
918		1007
919	However, C<ev_loop> can run an indefinite time, so it is not feasible to	1008	However, C<ev_run> can run an indefinite time, so it is not feasible
920	wait for it to return. One way around this is to wake up the loop via	1009	to wait for it to return. One way around this is to wake up the event
921	C<ev_unloop> and C<av_async_send>, another way is to set these I<release>	1010	loop via C<ev_break> and C<av_async_send>, another way is to set these
922	and I<acquire> callbacks on the loop.	1011	I<release> and I<acquire> callbacks on the loop.
923		1012
924	When set, then C<release> will be called just before the thread is	1013	When set, then C<release> will be called just before the thread is
925	suspended waiting for new events, and C<acquire> is called just	1014	suspended waiting for new events, and C<acquire> is called just
926	afterwards.	1015	afterwards.
927		1016
…		…
930		1019
931	While event loop modifications are allowed between invocations of	1020	While event loop modifications are allowed between invocations of
932	C<release> and C<acquire> (that's their only purpose after all), no	1021	C<release> and C<acquire> (that's their only purpose after all), no
933	modifications done will affect the event loop, i.e. adding watchers will	1022	modifications done will affect the event loop, i.e. adding watchers will
934	have no effect on the set of file descriptors being watched, or the time	1023	have no effect on the set of file descriptors being watched, or the time
935	waited. Use an C<ev_async> watcher to wake up C<ev_loop> when you want it	1024	waited. Use an C<ev_async> watcher to wake up C<ev_run> when you want it
936	to take note of any changes you made.	1025	to take note of any changes you made.
937		1026
938	In theory, threads executing C<ev_loop> will be async-cancel safe between	1027	In theory, threads executing C<ev_run> will be async-cancel safe between
939	invocations of C<release> and C<acquire>.	1028	invocations of C<release> and C<acquire>.
940		1029
941	See also the locking example in the C<THREADS> section later in this	1030	See also the locking example in the C<THREADS> section later in this
942	document.	1031	document.
943		1032
944	=item ev_set_userdata (loop, void *data)	1033	=item ev_set_userdata (loop, void *data)
945		1034
946	=item ev_userdata (loop)	1035	=item void *ev_userdata (loop)
947		1036
948	Set and retrieve a single C<void *> associated with a loop. When	1037	Set and retrieve a single C<void *> associated with a loop. When
949	C<ev_set_userdata> has never been called, then C<ev_userdata> returns	1038	C<ev_set_userdata> has never been called, then C<ev_userdata> returns
950	C<0.>	1039	C<0>.
951		1040
952	These two functions can be used to associate arbitrary data with a loop,	1041	These two functions can be used to associate arbitrary data with a loop,
953	and are intended solely for the C<invoke_pending_cb>, C<release> and	1042	and are intended solely for the C<invoke_pending_cb>, C<release> and
954	C<acquire> callbacks described above, but of course can be (ab-)used for	1043	C<acquire> callbacks described above, but of course can be (ab-)used for
955	any other purpose as well.	1044	any other purpose as well.
956		1045
957	=item ev_loop_verify (loop)	1046	=item ev_verify (loop)
958		1047
959	This function only does something when C<EV_VERIFY> support has been	1048	This function only does something when C<EV_VERIFY> support has been
960	compiled in, which is the default for non-minimal builds. It tries to go	1049	compiled in, which is the default for non-minimal builds. It tries to go
961	through all internal structures and checks them for validity. If anything	1050	through all internal structures and checks them for validity. If anything
962	is found to be inconsistent, it will print an error message to standard	1051	is found to be inconsistent, it will print an error message to standard
…		…
973		1062
974	In the following description, uppercase C<TYPE> in names stands for the	1063	In the following description, uppercase C<TYPE> in names stands for the
975	watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer	1064	watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer
976	watchers and C<ev_io_start> for I/O watchers.	1065	watchers and C<ev_io_start> for I/O watchers.
977		1066
978	A watcher is a structure that you create and register to record your	1067	A watcher is an opaque structure that you allocate and register to record
979	interest in some event. For instance, if you want to wait for STDIN to	1068	your interest in some event. To make a concrete example, imagine you want
980	become readable, you would create an C<ev_io> watcher for that:	1069	to wait for STDIN to become readable, you would create an C<ev_io> watcher
		1070	for that:
981		1071
982	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)	1072	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)
983	{	1073	{
984	ev_io_stop (w);	1074	ev_io_stop (w);
985	ev_unloop (loop, EVUNLOOP_ALL);	1075	ev_break (loop, EVBREAK_ALL);
986	}	1076	}
987		1077
988	struct ev_loop *loop = ev_default_loop (0);	1078	struct ev_loop *loop = ev_default_loop (0);
989		1079
990	ev_io stdin_watcher;	1080	ev_io stdin_watcher;
991		1081
992	ev_init (&stdin_watcher, my_cb);	1082	ev_init (&stdin_watcher, my_cb);
993	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	1083	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
994	ev_io_start (loop, &stdin_watcher);	1084	ev_io_start (loop, &stdin_watcher);
995		1085
996	ev_loop (loop, 0);	1086	ev_run (loop, 0);
997		1087
998	As you can see, you are responsible for allocating the memory for your	1088	As you can see, you are responsible for allocating the memory for your
999	watcher structures (and it is I<usually> a bad idea to do this on the	1089	watcher structures (and it is I<usually> a bad idea to do this on the
1000	stack).	1090	stack).
1001		1091
1002	Each watcher has an associated watcher structure (called C<struct ev_TYPE>	1092	Each watcher has an associated watcher structure (called C<struct ev_TYPE>
1003	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).	1093	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).
1004		1094
1005	Each watcher structure must be initialised by a call to C<ev_init	1095	Each watcher structure must be initialised by a call to C<ev_init (watcher
1006	(watcher *, callback)>, which expects a callback to be provided. This	1096	*, callback)>, which expects a callback to be provided. This callback is
1007	callback gets invoked each time the event occurs (or, in the case of I/O	1097	invoked each time the event occurs (or, in the case of I/O watchers, each
1008	watchers, each time the event loop detects that the file descriptor given	1098	time the event loop detects that the file descriptor given is readable
1009	is readable and/or writable).	1099	and/or writable).
1010		1100
1011	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>	1101	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>
1012	macro to configure it, with arguments specific to the watcher type. There	1102	macro to configure it, with arguments specific to the watcher type. There
1013	is also a macro to combine initialisation and setting in one call: C<<	1103	is also a macro to combine initialisation and setting in one call: C<<
1014	ev_TYPE_init (watcher *, callback, ...) >>.	1104	ev_TYPE_init (watcher *, callback, ...) >>.
…		…
1065		1155
1066	=item C<EV_PREPARE>	1156	=item C<EV_PREPARE>
1067		1157
1068	=item C<EV_CHECK>	1158	=item C<EV_CHECK>
1069		1159
1070	All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts	1160	All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts
1071	to gather new events, and all C<ev_check> watchers are invoked just after	1161	to gather new events, and all C<ev_check> watchers are invoked just after
1072	C<ev_loop> has gathered them, but before it invokes any callbacks for any	1162	C<ev_run> has gathered them, but before it invokes any callbacks for any
1073	received events. Callbacks of both watcher types can start and stop as	1163	received events. Callbacks of both watcher types can start and stop as
1074	many watchers as they want, and all of them will be taken into account	1164	many watchers as they want, and all of them will be taken into account
1075	(for example, a C<ev_prepare> watcher might start an idle watcher to keep	1165	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
1076	C<ev_loop> from blocking).	1166	C<ev_run> from blocking).
1077		1167
1078	=item C<EV_EMBED>	1168	=item C<EV_EMBED>
1079		1169
1080	The embedded event loop specified in the C<ev_embed> watcher needs attention.	1170	The embedded event loop specified in the C<ev_embed> watcher needs attention.
1081		1171
1082	=item C<EV_FORK>	1172	=item C<EV_FORK>
1083		1173
1084	The event loop has been resumed in the child process after fork (see	1174	The event loop has been resumed in the child process after fork (see
1085	C<ev_fork>).	1175	C<ev_fork>).
		1176
		1177	=item C<EV_CLEANUP>
		1178
		1179	The event loop is about to be destroyed (see C<ev_cleanup>).
1086		1180
1087	=item C<EV_ASYNC>	1181	=item C<EV_ASYNC>
1088		1182
1089	The given async watcher has been asynchronously notified (see C<ev_async>).	1183	The given async watcher has been asynchronously notified (see C<ev_async>).
1090		1184
…		…
1262		1356
1263	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related	1357	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related
1264	functions that do not need a watcher.	1358	functions that do not need a watcher.
1265		1359
1266	=back	1360	=back
1267
1268		1361
1269	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	1362	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
1270		1363
1271	Each watcher has, by default, a member C<void *data> that you can change	1364	Each watcher has, by default, a member C<void *data> that you can change
1272	and read at any time: libev will completely ignore it. This can be used	1365	and read at any time: libev will completely ignore it. This can be used
…		…
1328	t2_cb (EV_P_ ev_timer *w, int revents)	1421	t2_cb (EV_P_ ev_timer *w, int revents)
1329	{	1422	{
1330	struct my_biggy big = (struct my_biggy *)	1423	struct my_biggy big = (struct my_biggy *)
1331	(((char *)w) - offsetof (struct my_biggy, t2));	1424	(((char *)w) - offsetof (struct my_biggy, t2));
1332	}	1425	}
		1426
		1427	=head2 WATCHER STATES
		1428
		1429	There are various watcher states mentioned throughout this manual -
		1430	active, pending and so on. In this section these states and the rules to
		1431	transition between them will be described in more detail - and while these
		1432	rules might look complicated, they usually do "the right thing".
		1433
		1434	=over 4
		1435
		1436	=item initialiased
		1437
		1438	Before a watcher can be registered with the event looop it has to be
		1439	initialised. This can be done with a call to C<ev_TYPE_init>, or calls to
		1440	C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function.
		1441
		1442	In this state it is simply some block of memory that is suitable for use
		1443	in an event loop. It can be moved around, freed, reused etc. at will.
		1444
		1445	=item started/running/active
		1446
		1447	Once a watcher has been started with a call to C<ev_TYPE_start> it becomes
		1448	property of the event loop, and is actively waiting for events. While in
		1449	this state it cannot be accessed (except in a few documented ways), moved,
		1450	freed or anything else - the only legal thing is to keep a pointer to it,
		1451	and call libev functions on it that are documented to work on active watchers.
		1452
		1453	=item pending
		1454
		1455	If a watcher is active and libev determines that an event it is interested
		1456	in has occurred (such as a timer expiring), it will become pending. It will
		1457	stay in this pending state until either it is stopped or its callback is
		1458	about to be invoked, so it is not normally pending inside the watcher
		1459	callback.
		1460
		1461	The watcher might or might not be active while it is pending (for example,
		1462	an expired non-repeating timer can be pending but no longer active). If it
		1463	is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>),
		1464	but it is still property of the event loop at this time, so cannot be
		1465	moved, freed or reused. And if it is active the rules described in the
		1466	previous item still apply.
		1467
		1468	It is also possible to feed an event on a watcher that is not active (e.g.
		1469	via C<ev_feed_event>), in which case it becomes pending without being
		1470	active.
		1471
		1472	=item stopped
		1473
		1474	A watcher can be stopped implicitly by libev (in which case it might still
		1475	be pending), or explicitly by calling its C<ev_TYPE_stop> function. The
		1476	latter will clear any pending state the watcher might be in, regardless
		1477	of whether it was active or not, so stopping a watcher explicitly before
		1478	freeing it is often a good idea.
		1479
		1480	While stopped (and not pending) the watcher is essentially in the
		1481	initialised state, that is it can be reused, moved, modified in any way
		1482	you wish.
		1483
		1484	=back
1333		1485
1334	=head2 WATCHER PRIORITY MODELS	1486	=head2 WATCHER PRIORITY MODELS
1335		1487
1336	Many event loops support I<watcher priorities>, which are usually small	1488	Many event loops support I<watcher priorities>, which are usually small
1337	integers that influence the ordering of event callback invocation	1489	integers that influence the ordering of event callback invocation
…		…
1380		1532
1381	For example, to emulate how many other event libraries handle priorities,	1533	For example, to emulate how many other event libraries handle priorities,
1382	you can associate an C<ev_idle> watcher to each such watcher, and in	1534	you can associate an C<ev_idle> watcher to each such watcher, and in
1383	the normal watcher callback, you just start the idle watcher. The real	1535	the normal watcher callback, you just start the idle watcher. The real
1384	processing is done in the idle watcher callback. This causes libev to	1536	processing is done in the idle watcher callback. This causes libev to
1385	continously poll and process kernel event data for the watcher, but when	1537	continuously poll and process kernel event data for the watcher, but when
1386	the lock-out case is known to be rare (which in turn is rare :), this is	1538	the lock-out case is known to be rare (which in turn is rare :), this is
1387	workable.	1539	workable.
1388		1540
1389	Usually, however, the lock-out model implemented that way will perform	1541	Usually, however, the lock-out model implemented that way will perform
1390	miserably under the type of load it was designed to handle. In that case,	1542	miserably under the type of load it was designed to handle. In that case,
…		…
1464	In general you can register as many read and/or write event watchers per	1616	In general you can register as many read and/or write event watchers per
1465	fd as you want (as long as you don't confuse yourself). Setting all file	1617	fd as you want (as long as you don't confuse yourself). Setting all file
1466	descriptors to non-blocking mode is also usually a good idea (but not	1618	descriptors to non-blocking mode is also usually a good idea (but not
1467	required if you know what you are doing).	1619	required if you know what you are doing).
1468		1620
1469	If you cannot use non-blocking mode, then force the use of a
1470	known-to-be-good backend (at the time of this writing, this includes only
1471	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file
1472	descriptors for which non-blocking operation makes no sense (such as
1473	files) - libev doesn't guarentee any specific behaviour in that case.
1474
1475	Another thing you have to watch out for is that it is quite easy to	1621	Another thing you have to watch out for is that it is quite easy to
1476	receive "spurious" readiness notifications, that is your callback might	1622	receive "spurious" readiness notifications, that is, your callback might
1477	be called with C<EV_READ> but a subsequent C<read>(2) will actually block	1623	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
1478	because there is no data. Not only are some backends known to create a	1624	because there is no data. It is very easy to get into this situation even
1479	lot of those (for example Solaris ports), it is very easy to get into	1625	with a relatively standard program structure. Thus it is best to always
1480	this situation even with a relatively standard program structure. Thus	1626	use non-blocking I/O: An extra C<read>(2) returning C<EAGAIN> is far
1481	it is best to always use non-blocking I/O: An extra C<read>(2) returning
1482	C<EAGAIN> is far preferable to a program hanging until some data arrives.	1627	preferable to a program hanging until some data arrives.
1483		1628
1484	If you cannot run the fd in non-blocking mode (for example you should	1629	If you cannot run the fd in non-blocking mode (for example you should
1485	not play around with an Xlib connection), then you have to separately	1630	not play around with an Xlib connection), then you have to separately
1486	re-test whether a file descriptor is really ready with a known-to-be good	1631	re-test whether a file descriptor is really ready with a known-to-be good
1487	interface such as poll (fortunately in our Xlib example, Xlib already	1632	interface such as poll (fortunately in the case of Xlib, it already does
1488	does this on its own, so its quite safe to use). Some people additionally	1633	this on its own, so its quite safe to use). Some people additionally
1489	use C<SIGALRM> and an interval timer, just to be sure you won't block	1634	use C<SIGALRM> and an interval timer, just to be sure you won't block
1490	indefinitely.	1635	indefinitely.
1491		1636
1492	But really, best use non-blocking mode.	1637	But really, best use non-blocking mode.
1493		1638
…		…
1521		1666
1522	There is no workaround possible except not registering events	1667	There is no workaround possible except not registering events
1523	for potentially C<dup ()>'ed file descriptors, or to resort to	1668	for potentially C<dup ()>'ed file descriptors, or to resort to
1524	C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>.	1669	C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>.
1525		1670
		1671	=head3 The special problem of files
		1672
		1673	Many people try to use C<select> (or libev) on file descriptors
		1674	representing files, and expect it to become ready when their program
		1675	doesn't block on disk accesses (which can take a long time on their own).
		1676
		1677	However, this cannot ever work in the "expected" way - you get a readiness
		1678	notification as soon as the kernel knows whether and how much data is
		1679	there, and in the case of open files, that's always the case, so you
		1680	always get a readiness notification instantly, and your read (or possibly
		1681	write) will still block on the disk I/O.
		1682
		1683	Another way to view it is that in the case of sockets, pipes, character
		1684	devices and so on, there is another party (the sender) that delivers data
		1685	on it's own, but in the case of files, there is no such thing: the disk
		1686	will not send data on it's own, simply because it doesn't know what you
		1687	wish to read - you would first have to request some data.
		1688
		1689	Since files are typically not-so-well supported by advanced notification
		1690	mechanism, libev tries hard to emulate POSIX behaviour with respect
		1691	to files, even though you should not use it. The reason for this is
		1692	convenience: sometimes you want to watch STDIN or STDOUT, which is
		1693	usually a tty, often a pipe, but also sometimes files or special devices
		1694	(for example, C<epoll> on Linux works with F</dev/random> but not with
		1695	F</dev/urandom>), and even though the file might better be served with
		1696	asynchronous I/O instead of with non-blocking I/O, it is still useful when
		1697	it "just works" instead of freezing.
		1698
		1699	So avoid file descriptors pointing to files when you know it (e.g. use
		1700	libeio), but use them when it is convenient, e.g. for STDIN/STDOUT, or
		1701	when you rarely read from a file instead of from a socket, and want to
		1702	reuse the same code path.
		1703
1526	=head3 The special problem of fork	1704	=head3 The special problem of fork
1527		1705
1528	Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit	1706	Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit
1529	useless behaviour. Libev fully supports fork, but needs to be told about	1707	useless behaviour. Libev fully supports fork, but needs to be told about
1530	it in the child.	1708	it in the child if you want to continue to use it in the child.
1531		1709
1532	To support fork in your programs, you either have to call	1710	To support fork in your child processes, you have to call C<ev_loop_fork
1533	C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child,	1711	()> after a fork in the child, enable C<EVFLAG_FORKCHECK>, or resort to
1534	enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or	1712	C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>.
1535	C<EVBACKEND_POLL>.
1536		1713
1537	=head3 The special problem of SIGPIPE	1714	=head3 The special problem of SIGPIPE
1538		1715
1539	While not really specific to libev, it is easy to forget about C<SIGPIPE>:	1716	While not really specific to libev, it is easy to forget about C<SIGPIPE>:
1540	when writing to a pipe whose other end has been closed, your program gets	1717	when writing to a pipe whose other end has been closed, your program gets
…		…
1622	...	1799	...
1623	struct ev_loop *loop = ev_default_init (0);	1800	struct ev_loop *loop = ev_default_init (0);
1624	ev_io stdin_readable;	1801	ev_io stdin_readable;
1625	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1802	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1626	ev_io_start (loop, &stdin_readable);	1803	ev_io_start (loop, &stdin_readable);
1627	ev_loop (loop, 0);	1804	ev_run (loop, 0);
1628		1805
1629		1806
1630	=head2 C<ev_timer> - relative and optionally repeating timeouts	1807	=head2 C<ev_timer> - relative and optionally repeating timeouts
1631		1808
1632	Timer watchers are simple relative timers that generate an event after a	1809	Timer watchers are simple relative timers that generate an event after a
…		…
1641	The callback is guaranteed to be invoked only I<after> its timeout has	1818	The callback is guaranteed to be invoked only I<after> its timeout has
1642	passed (not I<at>, so on systems with very low-resolution clocks this	1819	passed (not I<at>, so on systems with very low-resolution clocks this
1643	might introduce a small delay). If multiple timers become ready during the	1820	might introduce a small delay). If multiple timers become ready during the
1644	same loop iteration then the ones with earlier time-out values are invoked	1821	same loop iteration then the ones with earlier time-out values are invoked
1645	before ones of the same priority with later time-out values (but this is	1822	before ones of the same priority with later time-out values (but this is
1646	no longer true when a callback calls C<ev_loop> recursively).	1823	no longer true when a callback calls C<ev_run> recursively).
1647		1824
1648	=head3 Be smart about timeouts	1825	=head3 Be smart about timeouts
1649		1826
1650	Many real-world problems involve some kind of timeout, usually for error	1827	Many real-world problems involve some kind of timeout, usually for error
1651	recovery. A typical example is an HTTP request - if the other side hangs,	1828	recovery. A typical example is an HTTP request - if the other side hangs,
…		…
1737	ev_tstamp timeout = last_activity + 60.;	1914	ev_tstamp timeout = last_activity + 60.;
1738		1915
1739	// if last_activity + 60. is older than now, we did time out	1916	// if last_activity + 60. is older than now, we did time out
1740	if (timeout < now)	1917	if (timeout < now)
1741	{	1918	{
1742	// timeout occured, take action	1919	// timeout occurred, take action
1743	}	1920	}
1744	else	1921	else
1745	{	1922	{
1746	// callback was invoked, but there was some activity, re-arm	1923	// callback was invoked, but there was some activity, re-arm
1747	// the watcher to fire in last_activity + 60, which is	1924	// the watcher to fire in last_activity + 60, which is
…		…
1822		1999
1823	=head3 The special problem of time updates	2000	=head3 The special problem of time updates
1824		2001
1825	Establishing the current time is a costly operation (it usually takes at	2002	Establishing the current time is a costly operation (it usually takes at
1826	least two system calls): EV therefore updates its idea of the current	2003	least two system calls): EV therefore updates its idea of the current
1827	time only before and after C<ev_loop> collects new events, which causes a	2004	time only before and after C<ev_run> collects new events, which causes a
1828	growing difference between C<ev_now ()> and C<ev_time ()> when handling	2005	growing difference between C<ev_now ()> and C<ev_time ()> when handling
1829	lots of events in one iteration.	2006	lots of events in one iteration.
1830		2007
1831	The relative timeouts are calculated relative to the C<ev_now ()>	2008	The relative timeouts are calculated relative to the C<ev_now ()>
1832	time. This is usually the right thing as this timestamp refers to the time	2009	time. This is usually the right thing as this timestamp refers to the time
…		…
1949	}	2126	}
1950		2127
1951	ev_timer mytimer;	2128	ev_timer mytimer;
1952	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	2129	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1953	ev_timer_again (&mytimer); /* start timer */	2130	ev_timer_again (&mytimer); /* start timer */
1954	ev_loop (loop, 0);	2131	ev_run (loop, 0);
1955		2132
1956	// and in some piece of code that gets executed on any "activity":	2133	// and in some piece of code that gets executed on any "activity":
1957	// reset the timeout to start ticking again at 10 seconds	2134	// reset the timeout to start ticking again at 10 seconds
1958	ev_timer_again (&mytimer);	2135	ev_timer_again (&mytimer);
1959		2136
…		…
1985		2162
1986	As with timers, the callback is guaranteed to be invoked only when the	2163	As with timers, the callback is guaranteed to be invoked only when the
1987	point in time where it is supposed to trigger has passed. If multiple	2164	point in time where it is supposed to trigger has passed. If multiple
1988	timers become ready during the same loop iteration then the ones with	2165	timers become ready during the same loop iteration then the ones with
1989	earlier time-out values are invoked before ones with later time-out values	2166	earlier time-out values are invoked before ones with later time-out values
1990	(but this is no longer true when a callback calls C<ev_loop> recursively).	2167	(but this is no longer true when a callback calls C<ev_run> recursively).
1991		2168
1992	=head3 Watcher-Specific Functions and Data Members	2169	=head3 Watcher-Specific Functions and Data Members
1993		2170
1994	=over 4	2171	=over 4
1995		2172
…		…
2123	Example: Call a callback every hour, or, more precisely, whenever the	2300	Example: Call a callback every hour, or, more precisely, whenever the
2124	system time is divisible by 3600. The callback invocation times have	2301	system time is divisible by 3600. The callback invocation times have
2125	potentially a lot of jitter, but good long-term stability.	2302	potentially a lot of jitter, but good long-term stability.
2126		2303
2127	static void	2304	static void
2128	clock_cb (struct ev_loop *loop, ev_io *w, int revents)	2305	clock_cb (struct ev_loop *loop, ev_periodic *w, int revents)
2129	{	2306	{
2130	... its now a full hour (UTC, or TAI or whatever your clock follows)	2307	... its now a full hour (UTC, or TAI or whatever your clock follows)
2131	}	2308	}
2132		2309
2133	ev_periodic hourly_tick;	2310	ev_periodic hourly_tick;
…		…
2156		2333
2157	=head2 C<ev_signal> - signal me when a signal gets signalled!	2334	=head2 C<ev_signal> - signal me when a signal gets signalled!
2158		2335
2159	Signal watchers will trigger an event when the process receives a specific	2336	Signal watchers will trigger an event when the process receives a specific
2160	signal one or more times. Even though signals are very asynchronous, libev	2337	signal one or more times. Even though signals are very asynchronous, libev
2161	will try it's best to deliver signals synchronously, i.e. as part of the	2338	will try its best to deliver signals synchronously, i.e. as part of the
2162	normal event processing, like any other event.	2339	normal event processing, like any other event.
2163		2340
2164	If you want signals to be delivered truly asynchronously, just use	2341	If you want signals to be delivered truly asynchronously, just use
2165	C<sigaction> as you would do without libev and forget about sharing	2342	C<sigaction> as you would do without libev and forget about sharing
2166	the signal. You can even use C<ev_async> from a signal handler to	2343	the signal. You can even use C<ev_async> from a signal handler to
…		…
2209		2386
2210	So I can't stress this enough: I<If you do not reset your signal mask when	2387	So I can't stress this enough: I<If you do not reset your signal mask when
2211	you expect it to be empty, you have a race condition in your code>. This	2388	you expect it to be empty, you have a race condition in your code>. This
2212	is not a libev-specific thing, this is true for most event libraries.	2389	is not a libev-specific thing, this is true for most event libraries.
2213		2390
		2391	=head3 The special problem of threads signal handling
		2392
		2393	POSIX threads has problematic signal handling semantics, specifically,
		2394	a lot of functionality (sigfd, sigwait etc.) only really works if all
		2395	threads in a process block signals, which is hard to achieve.
		2396
		2397	When you want to use sigwait (or mix libev signal handling with your own
		2398	for the same signals), you can tackle this problem by globally blocking
		2399	all signals before creating any threads (or creating them with a fully set
		2400	sigprocmask) and also specifying the C<EVFLAG_NOSIGMASK> when creating
		2401	loops. Then designate one thread as "signal receiver thread" which handles
		2402	these signals. You can pass on any signals that libev might be interested
		2403	in by calling C<ev_feed_signal>.
		2404
2214	=head3 Watcher-Specific Functions and Data Members	2405	=head3 Watcher-Specific Functions and Data Members
2215		2406
2216	=over 4	2407	=over 4
2217		2408
2218	=item ev_signal_init (ev_signal *, callback, int signum)	2409	=item ev_signal_init (ev_signal *, callback, int signum)
…		…
2233	Example: Try to exit cleanly on SIGINT.	2424	Example: Try to exit cleanly on SIGINT.
2234		2425
2235	static void	2426	static void
2236	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)	2427	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)
2237	{	2428	{
2238	ev_unloop (loop, EVUNLOOP_ALL);	2429	ev_break (loop, EVBREAK_ALL);
2239	}	2430	}
2240		2431
2241	ev_signal signal_watcher;	2432	ev_signal signal_watcher;
2242	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	2433	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
2243	ev_signal_start (loop, &signal_watcher);	2434	ev_signal_start (loop, &signal_watcher);
…		…
2629		2820
2630	Prepare and check watchers are usually (but not always) used in pairs:	2821	Prepare and check watchers are usually (but not always) used in pairs:
2631	prepare watchers get invoked before the process blocks and check watchers	2822	prepare watchers get invoked before the process blocks and check watchers
2632	afterwards.	2823	afterwards.
2633		2824
2634	You I<must not> call C<ev_loop> or similar functions that enter	2825	You I<must not> call C<ev_run> or similar functions that enter
2635	the current event loop from either C<ev_prepare> or C<ev_check>	2826	the current event loop from either C<ev_prepare> or C<ev_check>
2636	watchers. Other loops than the current one are fine, however. The	2827	watchers. Other loops than the current one are fine, however. The
2637	rationale behind this is that you do not need to check for recursion in	2828	rationale behind this is that you do not need to check for recursion in
2638	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,	2829	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,
2639	C<ev_check> so if you have one watcher of each kind they will always be	2830	C<ev_check> so if you have one watcher of each kind they will always be
…		…
2807		2998
2808	if (timeout >= 0)	2999	if (timeout >= 0)
2809	// create/start timer	3000	// create/start timer
2810		3001
2811	// poll	3002	// poll
2812	ev_loop (EV_A_ 0);	3003	ev_run (EV_A_ 0);
2813		3004
2814	// stop timer again	3005	// stop timer again
2815	if (timeout >= 0)	3006	if (timeout >= 0)
2816	ev_timer_stop (EV_A_ &to);	3007	ev_timer_stop (EV_A_ &to);
2817		3008
…		…
2895	if you do not want that, you need to temporarily stop the embed watcher).	3086	if you do not want that, you need to temporarily stop the embed watcher).
2896		3087
2897	=item ev_embed_sweep (loop, ev_embed *)	3088	=item ev_embed_sweep (loop, ev_embed *)
2898		3089
2899	Make a single, non-blocking sweep over the embedded loop. This works	3090	Make a single, non-blocking sweep over the embedded loop. This works
2900	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	3091	similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most
2901	appropriate way for embedded loops.	3092	appropriate way for embedded loops.
2902		3093
2903	=item struct ev_loop *other [read-only]	3094	=item struct ev_loop *other [read-only]
2904		3095
2905	The embedded event loop.	3096	The embedded event loop.
…		…
2965	C<ev_default_fork> cheats and calls it in the wrong process, the fork	3156	C<ev_default_fork> cheats and calls it in the wrong process, the fork
2966	handlers will be invoked, too, of course.	3157	handlers will be invoked, too, of course.
2967		3158
2968	=head3 The special problem of life after fork - how is it possible?	3159	=head3 The special problem of life after fork - how is it possible?
2969		3160
2970	Most uses of C<fork()> consist of forking, then some simple calls to ste	3161	Most uses of C<fork()> consist of forking, then some simple calls to set
2971	up/change the process environment, followed by a call to C<exec()>. This	3162	up/change the process environment, followed by a call to C<exec()>. This
2972	sequence should be handled by libev without any problems.	3163	sequence should be handled by libev without any problems.
2973		3164
2974	This changes when the application actually wants to do event handling	3165	This changes when the application actually wants to do event handling
2975	in the child, or both parent in child, in effect "continuing" after the	3166	in the child, or both parent in child, in effect "continuing" after the
…		…
2991	disadvantage of having to use multiple event loops (which do not support	3182	disadvantage of having to use multiple event loops (which do not support
2992	signal watchers).	3183	signal watchers).
2993		3184
2994	When this is not possible, or you want to use the default loop for	3185	When this is not possible, or you want to use the default loop for
2995	other reasons, then in the process that wants to start "fresh", call	3186	other reasons, then in the process that wants to start "fresh", call
2996	C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying	3187	C<ev_loop_destroy (EV_DEFAULT)> followed by C<ev_default_loop (...)>.
2997	the default loop will "orphan" (not stop) all registered watchers, so you	3188	Destroying the default loop will "orphan" (not stop) all registered
2998	have to be careful not to execute code that modifies those watchers. Note	3189	watchers, so you have to be careful not to execute code that modifies
2999	also that in that case, you have to re-register any signal watchers.	3190	those watchers. Note also that in that case, you have to re-register any
		3191	signal watchers.
3000		3192
3001	=head3 Watcher-Specific Functions and Data Members	3193	=head3 Watcher-Specific Functions and Data Members
3002		3194
3003	=over 4	3195	=over 4
3004		3196
3005	=item ev_fork_init (ev_signal *, callback)	3197	=item ev_fork_init (ev_fork *, callback)
3006		3198
3007	Initialises and configures the fork watcher - it has no parameters of any	3199	Initialises and configures the fork watcher - it has no parameters of any
3008	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,	3200	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
3009	believe me.	3201	really.
3010		3202
3011	=back	3203	=back
3012		3204
3013		3205
		3206	=head2 C<ev_cleanup> - even the best things end
		3207
		3208	Cleanup watchers are called just before the event loop is being destroyed
		3209	by a call to C<ev_loop_destroy>.
		3210
		3211	While there is no guarantee that the event loop gets destroyed, cleanup
		3212	watchers provide a convenient method to install cleanup hooks for your
		3213	program, worker threads and so on - you just to make sure to destroy the
		3214	loop when you want them to be invoked.
		3215
		3216	Cleanup watchers are invoked in the same way as any other watcher. Unlike
		3217	all other watchers, they do not keep a reference to the event loop (which
		3218	makes a lot of sense if you think about it). Like all other watchers, you
		3219	can call libev functions in the callback, except C<ev_cleanup_start>.
		3220
		3221	=head3 Watcher-Specific Functions and Data Members
		3222
		3223	=over 4
		3224
		3225	=item ev_cleanup_init (ev_cleanup *, callback)
		3226
		3227	Initialises and configures the cleanup watcher - it has no parameters of
		3228	any kind. There is a C<ev_cleanup_set> macro, but using it is utterly
		3229	pointless, I assure you.
		3230
		3231	=back
		3232
		3233	Example: Register an atexit handler to destroy the default loop, so any
		3234	cleanup functions are called.
		3235
		3236	static void
		3237	program_exits (void)
		3238	{
		3239	ev_loop_destroy (EV_DEFAULT_UC);
		3240	}
		3241
		3242	...
		3243	atexit (program_exits);
		3244
		3245
3014	=head2 C<ev_async> - how to wake up another event loop	3246	=head2 C<ev_async> - how to wake up an event loop
3015		3247
3016	In general, you cannot use an C<ev_loop> from multiple threads or other	3248	In general, you cannot use an C<ev_run> from multiple threads or other
3017	asynchronous sources such as signal handlers (as opposed to multiple event	3249	asynchronous sources such as signal handlers (as opposed to multiple event
3018	loops - those are of course safe to use in different threads).	3250	loops - those are of course safe to use in different threads).
3019		3251
3020	Sometimes, however, you need to wake up another event loop you do not	3252	Sometimes, however, you need to wake up an event loop you do not control,
3021	control, for example because it belongs to another thread. This is what	3253	for example because it belongs to another thread. This is what C<ev_async>
3022	C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you	3254	watchers do: as long as the C<ev_async> watcher is active, you can signal
3023	can signal it by calling C<ev_async_send>, which is thread- and signal	3255	it by calling C<ev_async_send>, which is thread- and signal safe.
3024	safe.
3025		3256
3026	This functionality is very similar to C<ev_signal> watchers, as signals,	3257	This functionality is very similar to C<ev_signal> watchers, as signals,
3027	too, are asynchronous in nature, and signals, too, will be compressed	3258	too, are asynchronous in nature, and signals, too, will be compressed
3028	(i.e. the number of callback invocations may be less than the number of	3259	(i.e. the number of callback invocations may be less than the number of
3029	C<ev_async_sent> calls).	3260	C<ev_async_sent> calls). In fact, you could use signal watchers as a kind
		3261	of "global async watchers" by using a watcher on an otherwise unused
		3262	signal, and C<ev_feed_signal> to signal this watcher from another thread,
		3263	even without knowing which loop owns the signal.
3030		3264
3031	Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not	3265	Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not
3032	just the default loop.	3266	just the default loop.
3033		3267
3034	=head3 Queueing	3268	=head3 Queueing
…		…
3210	Feed an event on the given fd, as if a file descriptor backend detected	3444	Feed an event on the given fd, as if a file descriptor backend detected
3211	the given events it.	3445	the given events it.
3212		3446
3213	=item ev_feed_signal_event (loop, int signum)	3447	=item ev_feed_signal_event (loop, int signum)
3214		3448
3215	Feed an event as if the given signal occurred (C<loop> must be the default	3449	Feed an event as if the given signal occurred. See also C<ev_feed_signal>,
3216	loop!).	3450	which is async-safe.
		3451
		3452	=back
		3453
		3454
		3455	=head1 COMMON OR USEFUL IDIOMS (OR BOTH)
		3456
		3457	This section explains some common idioms that are not immediately
		3458	obvious. Note that examples are sprinkled over the whole manual, and this
		3459	section only contains stuff that wouldn't fit anywhere else.
		3460
		3461	=over 4
		3462
		3463	=item Model/nested event loop invocations and exit conditions.
		3464
		3465	Often (especially in GUI toolkits) there are places where you have
		3466	I<modal> interaction, which is most easily implemented by recursively
		3467	invoking C<ev_run>.
		3468
		3469	This brings the problem of exiting - a callback might want to finish the
		3470	main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but
		3471	a modal "Are you sure?" dialog is still waiting), or just the nested one
		3472	and not the main one (e.g. user clocked "Ok" in a modal dialog), or some
		3473	other combination: In these cases, C<ev_break> will not work alone.
		3474
		3475	The solution is to maintain "break this loop" variable for each C<ev_run>
		3476	invocation, and use a loop around C<ev_run> until the condition is
		3477	triggered, using C<EVRUN_ONCE>:
		3478
		3479	// main loop
		3480	int exit_main_loop = 0;
		3481
		3482	while (!exit_main_loop)
		3483	ev_run (EV_DEFAULT_ EVRUN_ONCE);
		3484
		3485	// in a model watcher
		3486	int exit_nested_loop = 0;
		3487
		3488	while (!exit_nested_loop)
		3489	ev_run (EV_A_ EVRUN_ONCE);
		3490
		3491	To exit from any of these loops, just set the corresponding exit variable:
		3492
		3493	// exit modal loop
		3494	exit_nested_loop = 1;
		3495
		3496	// exit main program, after modal loop is finished
		3497	exit_main_loop = 1;
		3498
		3499	// exit both
		3500	exit_main_loop = exit_nested_loop = 1;
		3501
		3502	=item Thread locking example
		3503
		3504	Here is a fictitious example of how to run an event loop in a different
		3505	thread than where callbacks are being invoked and watchers are
		3506	created/added/removed.
		3507
		3508	For a real-world example, see the C<EV::Loop::Async> perl module,
		3509	which uses exactly this technique (which is suited for many high-level
		3510	languages).
		3511
		3512	The example uses a pthread mutex to protect the loop data, a condition
		3513	variable to wait for callback invocations, an async watcher to notify the
		3514	event loop thread and an unspecified mechanism to wake up the main thread.
		3515
		3516	First, you need to associate some data with the event loop:
		3517
		3518	typedef struct {
		3519	mutex_t lock; /* global loop lock */
		3520	ev_async async_w;
		3521	thread_t tid;
		3522	cond_t invoke_cv;
		3523	} userdata;
		3524
		3525	void prepare_loop (EV_P)
		3526	{
		3527	// for simplicity, we use a static userdata struct.
		3528	static userdata u;
		3529
		3530	ev_async_init (&u->async_w, async_cb);
		3531	ev_async_start (EV_A_ &u->async_w);
		3532
		3533	pthread_mutex_init (&u->lock, 0);
		3534	pthread_cond_init (&u->invoke_cv, 0);
		3535
		3536	// now associate this with the loop
		3537	ev_set_userdata (EV_A_ u);
		3538	ev_set_invoke_pending_cb (EV_A_ l_invoke);
		3539	ev_set_loop_release_cb (EV_A_ l_release, l_acquire);
		3540
		3541	// then create the thread running ev_loop
		3542	pthread_create (&u->tid, 0, l_run, EV_A);
		3543	}
		3544
		3545	The callback for the C<ev_async> watcher does nothing: the watcher is used
		3546	solely to wake up the event loop so it takes notice of any new watchers
		3547	that might have been added:
		3548
		3549	static void
		3550	async_cb (EV_P_ ev_async *w, int revents)
		3551	{
		3552	// just used for the side effects
		3553	}
		3554
		3555	The C<l_release> and C<l_acquire> callbacks simply unlock/lock the mutex
		3556	protecting the loop data, respectively.
		3557
		3558	static void
		3559	l_release (EV_P)
		3560	{
		3561	userdata *u = ev_userdata (EV_A);
		3562	pthread_mutex_unlock (&u->lock);
		3563	}
		3564
		3565	static void
		3566	l_acquire (EV_P)
		3567	{
		3568	userdata *u = ev_userdata (EV_A);
		3569	pthread_mutex_lock (&u->lock);
		3570	}
		3571
		3572	The event loop thread first acquires the mutex, and then jumps straight
		3573	into C<ev_run>:
		3574
		3575	void *
		3576	l_run (void *thr_arg)
		3577	{
		3578	struct ev_loop *loop = (struct ev_loop *)thr_arg;
		3579
		3580	l_acquire (EV_A);
		3581	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
		3582	ev_run (EV_A_ 0);
		3583	l_release (EV_A);
		3584
		3585	return 0;
		3586	}
		3587
		3588	Instead of invoking all pending watchers, the C<l_invoke> callback will
		3589	signal the main thread via some unspecified mechanism (signals? pipe
		3590	writes? C<Async::Interrupt>?) and then waits until all pending watchers
		3591	have been called (in a while loop because a) spurious wakeups are possible
		3592	and b) skipping inter-thread-communication when there are no pending
		3593	watchers is very beneficial):
		3594
		3595	static void
		3596	l_invoke (EV_P)
		3597	{
		3598	userdata *u = ev_userdata (EV_A);
		3599
		3600	while (ev_pending_count (EV_A))
		3601	{
		3602	wake_up_other_thread_in_some_magic_or_not_so_magic_way ();
		3603	pthread_cond_wait (&u->invoke_cv, &u->lock);
		3604	}
		3605	}
		3606
		3607	Now, whenever the main thread gets told to invoke pending watchers, it
		3608	will grab the lock, call C<ev_invoke_pending> and then signal the loop
		3609	thread to continue:
		3610
		3611	static void
		3612	real_invoke_pending (EV_P)
		3613	{
		3614	userdata *u = ev_userdata (EV_A);
		3615
		3616	pthread_mutex_lock (&u->lock);
		3617	ev_invoke_pending (EV_A);
		3618	pthread_cond_signal (&u->invoke_cv);
		3619	pthread_mutex_unlock (&u->lock);
		3620	}
		3621
		3622	Whenever you want to start/stop a watcher or do other modifications to an
		3623	event loop, you will now have to lock:
		3624
		3625	ev_timer timeout_watcher;
		3626	userdata *u = ev_userdata (EV_A);
		3627
		3628	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
		3629
		3630	pthread_mutex_lock (&u->lock);
		3631	ev_timer_start (EV_A_ &timeout_watcher);
		3632	ev_async_send (EV_A_ &u->async_w);
		3633	pthread_mutex_unlock (&u->lock);
		3634
		3635	Note that sending the C<ev_async> watcher is required because otherwise
		3636	an event loop currently blocking in the kernel will have no knowledge
		3637	about the newly added timer. By waking up the loop it will pick up any new
		3638	watchers in the next event loop iteration.
3217		3639
3218	=back	3640	=back
3219		3641
3220		3642
3221	=head1 LIBEVENT EMULATION	3643	=head1 LIBEVENT EMULATION
3222		3644
3223	Libev offers a compatibility emulation layer for libevent. It cannot	3645	Libev offers a compatibility emulation layer for libevent. It cannot
3224	emulate the internals of libevent, so here are some usage hints:	3646	emulate the internals of libevent, so here are some usage hints:
3225		3647
3226	=over 4	3648	=over 4
		3649
		3650	=item * Only the libevent-1.4.1-beta API is being emulated.
		3651
		3652	This was the newest libevent version available when libev was implemented,
		3653	and is still mostly unchanged in 2010.
3227		3654
3228	=item * Use it by including <event.h>, as usual.	3655	=item * Use it by including <event.h>, as usual.
3229		3656
3230	=item * The following members are fully supported: ev_base, ev_callback,	3657	=item * The following members are fully supported: ev_base, ev_callback,
3231	ev_arg, ev_fd, ev_res, ev_events.	3658	ev_arg, ev_fd, ev_res, ev_events.
…		…
3237	=item * Priorities are not currently supported. Initialising priorities	3664	=item * Priorities are not currently supported. Initialising priorities
3238	will fail and all watchers will have the same priority, even though there	3665	will fail and all watchers will have the same priority, even though there
3239	is an ev_pri field.	3666	is an ev_pri field.
3240		3667
3241	=item * In libevent, the last base created gets the signals, in libev, the	3668	=item * In libevent, the last base created gets the signals, in libev, the
3242	first base created (== the default loop) gets the signals.	3669	base that registered the signal gets the signals.
3243		3670
3244	=item * Other members are not supported.	3671	=item * Other members are not supported.
3245		3672
3246	=item * The libev emulation is I<not> ABI compatible to libevent, you need	3673	=item * The libev emulation is I<not> ABI compatible to libevent, you need
3247	to use the libev header file and library.	3674	to use the libev header file and library.
…		…
3266	Care has been taken to keep the overhead low. The only data member the C++	3693	Care has been taken to keep the overhead low. The only data member the C++
3267	classes add (compared to plain C-style watchers) is the event loop pointer	3694	classes add (compared to plain C-style watchers) is the event loop pointer
3268	that the watcher is associated with (or no additional members at all if	3695	that the watcher is associated with (or no additional members at all if
3269	you disable C<EV_MULTIPLICITY> when embedding libev).	3696	you disable C<EV_MULTIPLICITY> when embedding libev).
3270		3697
3271	Currently, functions, and static and non-static member functions can be	3698	Currently, functions, static and non-static member functions and classes
3272	used as callbacks. Other types should be easy to add as long as they only	3699	with C<operator ()> can be used as callbacks. Other types should be easy
3273	need one additional pointer for context. If you need support for other	3700	to add as long as they only need one additional pointer for context. If
3274	types of functors please contact the author (preferably after implementing	3701	you need support for other types of functors please contact the author
3275	it).	3702	(preferably after implementing it).
3276		3703
3277	Here is a list of things available in the C<ev> namespace:	3704	Here is a list of things available in the C<ev> namespace:
3278		3705
3279	=over 4	3706	=over 4
3280		3707
…		…
3341	myclass obj;	3768	myclass obj;
3342	ev::io iow;	3769	ev::io iow;
3343	iow.set <myclass, &myclass::io_cb> (&obj);	3770	iow.set <myclass, &myclass::io_cb> (&obj);
3344		3771
3345	=item w->set (object *)	3772	=item w->set (object *)
3346
3347	This is an B<experimental> feature that might go away in a future version.
3348		3773
3349	This is a variation of a method callback - leaving out the method to call	3774	This is a variation of a method callback - leaving out the method to call
3350	will default the method to C<operator ()>, which makes it possible to use	3775	will default the method to C<operator ()>, which makes it possible to use
3351	functor objects without having to manually specify the C<operator ()> all	3776	functor objects without having to manually specify the C<operator ()> all
3352	the time. Incidentally, you can then also leave out the template argument	3777	the time. Incidentally, you can then also leave out the template argument
…		…
3392	Associates a different C<struct ev_loop> with this watcher. You can only	3817	Associates a different C<struct ev_loop> with this watcher. You can only
3393	do this when the watcher is inactive (and not pending either).	3818	do this when the watcher is inactive (and not pending either).
3394		3819
3395	=item w->set ([arguments])	3820	=item w->set ([arguments])
3396		3821
3397	Basically the same as C<ev_TYPE_set>, with the same arguments. Must be	3822	Basically the same as C<ev_TYPE_set>, with the same arguments. Either this
3398	called at least once. Unlike the C counterpart, an active watcher gets	3823	method or a suitable start method must be called at least once. Unlike the
3399	automatically stopped and restarted when reconfiguring it with this	3824	C counterpart, an active watcher gets automatically stopped and restarted
3400	method.	3825	when reconfiguring it with this method.
3401		3826
3402	=item w->start ()	3827	=item w->start ()
3403		3828
3404	Starts the watcher. Note that there is no C<loop> argument, as the	3829	Starts the watcher. Note that there is no C<loop> argument, as the
3405	constructor already stores the event loop.	3830	constructor already stores the event loop.
3406		3831
		3832	=item w->start ([arguments])
		3833
		3834	Instead of calling C<set> and C<start> methods separately, it is often
		3835	convenient to wrap them in one call. Uses the same type of arguments as
		3836	the configure C<set> method of the watcher.
		3837
3407	=item w->stop ()	3838	=item w->stop ()
3408		3839
3409	Stops the watcher if it is active. Again, no C<loop> argument.	3840	Stops the watcher if it is active. Again, no C<loop> argument.
3410		3841
3411	=item w->again () (C<ev::timer>, C<ev::periodic> only)	3842	=item w->again () (C<ev::timer>, C<ev::periodic> only)
…		…
3423		3854
3424	=back	3855	=back
3425		3856
3426	=back	3857	=back
3427		3858
3428	Example: Define a class with an IO and idle watcher, start one of them in	3859	Example: Define a class with two I/O and idle watchers, start the I/O
3429	the constructor.	3860	watchers in the constructor.
3430		3861
3431	class myclass	3862	class myclass
3432	{	3863	{
3433	ev::io io ; void io_cb (ev::io &w, int revents);	3864	ev::io io ; void io_cb (ev::io &w, int revents);
		3865	ev::io2 io2 ; void io2_cb (ev::io &w, int revents);
3434	ev::idle idle; void idle_cb (ev::idle &w, int revents);	3866	ev::idle idle; void idle_cb (ev::idle &w, int revents);
3435		3867
3436	myclass (int fd)	3868	myclass (int fd)
3437	{	3869	{
3438	io .set <myclass, &myclass::io_cb > (this);	3870	io .set <myclass, &myclass::io_cb > (this);
		3871	io2 .set <myclass, &myclass::io2_cb > (this);
3439	idle.set <myclass, &myclass::idle_cb> (this);	3872	idle.set <myclass, &myclass::idle_cb> (this);
3440		3873
3441	io.start (fd, ev::READ);	3874	io.set (fd, ev::WRITE); // configure the watcher
		3875	io.start (); // start it whenever convenient
		3876
		3877	io2.start (fd, ev::READ); // set + start in one call
3442	}	3878	}
3443	};	3879	};
3444		3880
3445		3881
3446	=head1 OTHER LANGUAGE BINDINGS	3882	=head1 OTHER LANGUAGE BINDINGS
…		…
3520	loop argument"). The C<EV_A> form is used when this is the sole argument,	3956	loop argument"). The C<EV_A> form is used when this is the sole argument,
3521	C<EV_A_> is used when other arguments are following. Example:	3957	C<EV_A_> is used when other arguments are following. Example:
3522		3958
3523	ev_unref (EV_A);	3959	ev_unref (EV_A);
3524	ev_timer_add (EV_A_ watcher);	3960	ev_timer_add (EV_A_ watcher);
3525	ev_loop (EV_A_ 0);	3961	ev_run (EV_A_ 0);
3526		3962
3527	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	3963	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
3528	which is often provided by the following macro.	3964	which is often provided by the following macro.
3529		3965
3530	=item C<EV_P>, C<EV_P_>	3966	=item C<EV_P>, C<EV_P_>
…		…
3570	}	4006	}
3571		4007
3572	ev_check check;	4008	ev_check check;
3573	ev_check_init (&check, check_cb);	4009	ev_check_init (&check, check_cb);
3574	ev_check_start (EV_DEFAULT_ &check);	4010	ev_check_start (EV_DEFAULT_ &check);
3575	ev_loop (EV_DEFAULT_ 0);	4011	ev_run (EV_DEFAULT_ 0);
3576		4012
3577	=head1 EMBEDDING	4013	=head1 EMBEDDING
3578		4014
3579	Libev can (and often is) directly embedded into host	4015	Libev can (and often is) directly embedded into host
3580	applications. Examples of applications that embed it include the Deliantra	4016	applications. Examples of applications that embed it include the Deliantra
…		…
3671	to a compiled library. All other symbols change the ABI, which means all	4107	to a compiled library. All other symbols change the ABI, which means all
3672	users of libev and the libev code itself must be compiled with compatible	4108	users of libev and the libev code itself must be compiled with compatible
3673	settings.	4109	settings.
3674		4110
3675	=over 4	4111	=over 4
		4112
		4113	=item EV_COMPAT3 (h)
		4114
		4115	Backwards compatibility is a major concern for libev. This is why this
		4116	release of libev comes with wrappers for the functions and symbols that
		4117	have been renamed between libev version 3 and 4.
		4118
		4119	You can disable these wrappers (to test compatibility with future
		4120	versions) by defining C<EV_COMPAT3> to C<0> when compiling your
		4121	sources. This has the additional advantage that you can drop the C<struct>
		4122	from C<struct ev_loop> declarations, as libev will provide an C<ev_loop>
		4123	typedef in that case.
		4124
		4125	In some future version, the default for C<EV_COMPAT3> will become C<0>,
		4126	and in some even more future version the compatibility code will be
		4127	removed completely.
3676		4128
3677	=item EV_STANDALONE (h)	4129	=item EV_STANDALONE (h)
3678		4130
3679	Must always be C<1> if you do not use autoconf configuration, which	4131	Must always be C<1> if you do not use autoconf configuration, which
3680	keeps libev from including F<config.h>, and it also defines dummy	4132	keeps libev from including F<config.h>, and it also defines dummy
…		…
3887	EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE,	4339	EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE,
3888	EV_ASYNC_ENABLE, EV_CHILD_ENABLE.	4340	EV_ASYNC_ENABLE, EV_CHILD_ENABLE.
3889		4341
3890	If undefined or defined to be C<1> (and the platform supports it), then	4342	If undefined or defined to be C<1> (and the platform supports it), then
3891	the respective watcher type is supported. If defined to be C<0>, then it	4343	the respective watcher type is supported. If defined to be C<0>, then it
3892	is not. Disabling watcher types mainly saves codesize.	4344	is not. Disabling watcher types mainly saves code size.
3893		4345
3894	=item EV_FEATURES	4346	=item EV_FEATURES
3895		4347
3896	If you need to shave off some kilobytes of code at the expense of some	4348	If you need to shave off some kilobytes of code at the expense of some
3897	speed (but with the full API), you can define this symbol to request	4349	speed (but with the full API), you can define this symbol to request
…		…
3917		4369
3918	=item C<1> - faster/larger code	4370	=item C<1> - faster/larger code
3919		4371
3920	Use larger code to speed up some operations.	4372	Use larger code to speed up some operations.
3921		4373
3922	Currently this is used to override some inlining decisions (enlarging the roughly	4374	Currently this is used to override some inlining decisions (enlarging the
3923	30% code size on amd64.	4375	code size by roughly 30% on amd64).
3924		4376
3925	When optimising for size, use of compiler flags such as C<-Os> with	4377	When optimising for size, use of compiler flags such as C<-Os> with
3926	gcc recommended, as well as C<-DNDEBUG>, as libev contains a number of	4378	gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of
3927	assertions.	4379	assertions.
3928		4380
3929	=item C<2> - faster/larger data structures	4381	=item C<2> - faster/larger data structures
3930		4382
3931	Replaces the small 2-heap for timer management by a faster 4-heap, larger	4383	Replaces the small 2-heap for timer management by a faster 4-heap, larger
3932	hash table sizes and so on. This will usually further increase codesize	4384	hash table sizes and so on. This will usually further increase code size
3933	and can additionally have an effect on the size of data structures at	4385	and can additionally have an effect on the size of data structures at
3934	runtime.	4386	runtime.
3935		4387
3936	=item C<4> - full API configuration	4388	=item C<4> - full API configuration
3937		4389
…		…
3974	I/O watcher then might come out at only 5Kb.	4426	I/O watcher then might come out at only 5Kb.
3975		4427
3976	=item EV_AVOID_STDIO	4428	=item EV_AVOID_STDIO
3977		4429
3978	If this is set to C<1> at compiletime, then libev will avoid using stdio	4430	If this is set to C<1> at compiletime, then libev will avoid using stdio
3979	functions (printf, scanf, perror etc.). This will increase the codesize	4431	functions (printf, scanf, perror etc.). This will increase the code size
3980	somewhat, but if your program doesn't otherwise depend on stdio and your	4432	somewhat, but if your program doesn't otherwise depend on stdio and your
3981	libc allows it, this avoids linking in the stdio library which is quite	4433	libc allows it, this avoids linking in the stdio library which is quite
3982	big.	4434	big.
3983		4435
3984	Note that error messages might become less precise when this option is	4436	Note that error messages might become less precise when this option is
…		…
3988		4440
3989	The highest supported signal number, +1 (or, the number of	4441	The highest supported signal number, +1 (or, the number of
3990	signals): Normally, libev tries to deduce the maximum number of signals	4442	signals): Normally, libev tries to deduce the maximum number of signals
3991	automatically, but sometimes this fails, in which case it can be	4443	automatically, but sometimes this fails, in which case it can be
3992	specified. Also, using a lower number than detected (C<32> should be	4444	specified. Also, using a lower number than detected (C<32> should be
3993	good for about any system in existance) can save some memory, as libev	4445	good for about any system in existence) can save some memory, as libev
3994	statically allocates some 12-24 bytes per signal number.	4446	statically allocates some 12-24 bytes per signal number.
3995		4447
3996	=item EV_PID_HASHSIZE	4448	=item EV_PID_HASHSIZE
3997		4449
3998	C<ev_child> watchers use a small hash table to distribute workload by	4450	C<ev_child> watchers use a small hash table to distribute workload by
…		…
4030	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it	4482	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
4031	will be C<0>.	4483	will be C<0>.
4032		4484
4033	=item EV_VERIFY	4485	=item EV_VERIFY
4034		4486
4035	Controls how much internal verification (see C<ev_loop_verify ()>) will	4487	Controls how much internal verification (see C<ev_verify ()>) will
4036	be done: If set to C<0>, no internal verification code will be compiled	4488	be done: If set to C<0>, no internal verification code will be compiled
4037	in. If set to C<1>, then verification code will be compiled in, but not	4489	in. If set to C<1>, then verification code will be compiled in, but not
4038	called. If set to C<2>, then the internal verification code will be	4490	called. If set to C<2>, then the internal verification code will be
4039	called once per loop, which can slow down libev. If set to C<3>, then the	4491	called once per loop, which can slow down libev. If set to C<3>, then the
4040	verification code will be called very frequently, which will slow down	4492	verification code will be called very frequently, which will slow down
…		…
4044	will be C<0>.	4496	will be C<0>.
4045		4497
4046	=item EV_COMMON	4498	=item EV_COMMON
4047		4499
4048	By default, all watchers have a C<void *data> member. By redefining	4500	By default, all watchers have a C<void *data> member. By redefining
4049	this macro to a something else you can include more and other types of	4501	this macro to something else you can include more and other types of
4050	members. You have to define it each time you include one of the files,	4502	members. You have to define it each time you include one of the files,
4051	though, and it must be identical each time.	4503	though, and it must be identical each time.
4052		4504
4053	For example, the perl EV module uses something like this:	4505	For example, the perl EV module uses something like this:
4054		4506
…		…
4184	default loop and triggering an C<ev_async> watcher from the default loop	4636	default loop and triggering an C<ev_async> watcher from the default loop
4185	watcher callback into the event loop interested in the signal.	4637	watcher callback into the event loop interested in the signal.
4186		4638
4187	=back	4639	=back
4188		4640
4189	=head4 THREAD LOCKING EXAMPLE	4641	See also L<Thread locking example>.
4190
4191	Here is a fictitious example of how to run an event loop in a different
4192	thread than where callbacks are being invoked and watchers are
4193	created/added/removed.
4194
4195	For a real-world example, see the C<EV::Loop::Async> perl module,
4196	which uses exactly this technique (which is suited for many high-level
4197	languages).
4198
4199	The example uses a pthread mutex to protect the loop data, a condition
4200	variable to wait for callback invocations, an async watcher to notify the
4201	event loop thread and an unspecified mechanism to wake up the main thread.
4202
4203	First, you need to associate some data with the event loop:
4204
4205	typedef struct {
4206	mutex_t lock; /* global loop lock */
4207	ev_async async_w;
4208	thread_t tid;
4209	cond_t invoke_cv;
4210	} userdata;
4211
4212	void prepare_loop (EV_P)
4213	{
4214	// for simplicity, we use a static userdata struct.
4215	static userdata u;
4216
4217	ev_async_init (&u->async_w, async_cb);
4218	ev_async_start (EV_A_ &u->async_w);
4219
4220	pthread_mutex_init (&u->lock, 0);
4221	pthread_cond_init (&u->invoke_cv, 0);
4222
4223	// now associate this with the loop
4224	ev_set_userdata (EV_A_ u);
4225	ev_set_invoke_pending_cb (EV_A_ l_invoke);
4226	ev_set_loop_release_cb (EV_A_ l_release, l_acquire);
4227
4228	// then create the thread running ev_loop
4229	pthread_create (&u->tid, 0, l_run, EV_A);
4230	}
4231
4232	The callback for the C<ev_async> watcher does nothing: the watcher is used
4233	solely to wake up the event loop so it takes notice of any new watchers
4234	that might have been added:
4235
4236	static void
4237	async_cb (EV_P_ ev_async *w, int revents)
4238	{
4239	// just used for the side effects
4240	}
4241
4242	The C<l_release> and C<l_acquire> callbacks simply unlock/lock the mutex
4243	protecting the loop data, respectively.
4244
4245	static void
4246	l_release (EV_P)
4247	{
4248	userdata *u = ev_userdata (EV_A);
4249	pthread_mutex_unlock (&u->lock);
4250	}
4251
4252	static void
4253	l_acquire (EV_P)
4254	{
4255	userdata *u = ev_userdata (EV_A);
4256	pthread_mutex_lock (&u->lock);
4257	}
4258
4259	The event loop thread first acquires the mutex, and then jumps straight
4260	into C<ev_loop>:
4261
4262	void *
4263	l_run (void *thr_arg)
4264	{
4265	struct ev_loop *loop = (struct ev_loop *)thr_arg;
4266
4267	l_acquire (EV_A);
4268	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
4269	ev_loop (EV_A_ 0);
4270	l_release (EV_A);
4271
4272	return 0;
4273	}
4274
4275	Instead of invoking all pending watchers, the C<l_invoke> callback will
4276	signal the main thread via some unspecified mechanism (signals? pipe
4277	writes? C<Async::Interrupt>?) and then waits until all pending watchers
4278	have been called (in a while loop because a) spurious wakeups are possible
4279	and b) skipping inter-thread-communication when there are no pending
4280	watchers is very beneficial):
4281
4282	static void
4283	l_invoke (EV_P)
4284	{
4285	userdata *u = ev_userdata (EV_A);
4286
4287	while (ev_pending_count (EV_A))
4288	{
4289	wake_up_other_thread_in_some_magic_or_not_so_magic_way ();
4290	pthread_cond_wait (&u->invoke_cv, &u->lock);
4291	}
4292	}
4293
4294	Now, whenever the main thread gets told to invoke pending watchers, it
4295	will grab the lock, call C<ev_invoke_pending> and then signal the loop
4296	thread to continue:
4297
4298	static void
4299	real_invoke_pending (EV_P)
4300	{
4301	userdata *u = ev_userdata (EV_A);
4302
4303	pthread_mutex_lock (&u->lock);
4304	ev_invoke_pending (EV_A);
4305	pthread_cond_signal (&u->invoke_cv);
4306	pthread_mutex_unlock (&u->lock);
4307	}
4308
4309	Whenever you want to start/stop a watcher or do other modifications to an
4310	event loop, you will now have to lock:
4311
4312	ev_timer timeout_watcher;
4313	userdata *u = ev_userdata (EV_A);
4314
4315	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
4316
4317	pthread_mutex_lock (&u->lock);
4318	ev_timer_start (EV_A_ &timeout_watcher);
4319	ev_async_send (EV_A_ &u->async_w);
4320	pthread_mutex_unlock (&u->lock);
4321
4322	Note that sending the C<ev_async> watcher is required because otherwise
4323	an event loop currently blocking in the kernel will have no knowledge
4324	about the newly added timer. By waking up the loop it will pick up any new
4325	watchers in the next event loop iteration.
4326		4642
4327	=head3 COROUTINES	4643	=head3 COROUTINES
4328		4644
4329	Libev is very accommodating to coroutines ("cooperative threads"):	4645	Libev is very accommodating to coroutines ("cooperative threads"):
4330	libev fully supports nesting calls to its functions from different	4646	libev fully supports nesting calls to its functions from different
4331	coroutines (e.g. you can call C<ev_loop> on the same loop from two	4647	coroutines (e.g. you can call C<ev_run> on the same loop from two
4332	different coroutines, and switch freely between both coroutines running	4648	different coroutines, and switch freely between both coroutines running
4333	the loop, as long as you don't confuse yourself). The only exception is	4649	the loop, as long as you don't confuse yourself). The only exception is
4334	that you must not do this from C<ev_periodic> reschedule callbacks.	4650	that you must not do this from C<ev_periodic> reschedule callbacks.
4335		4651
4336	Care has been taken to ensure that libev does not keep local state inside	4652	Care has been taken to ensure that libev does not keep local state inside
4337	C<ev_loop>, and other calls do not usually allow for coroutine switches as	4653	C<ev_run>, and other calls do not usually allow for coroutine switches as
4338	they do not call any callbacks.	4654	they do not call any callbacks.
4339		4655
4340	=head2 COMPILER WARNINGS	4656	=head2 COMPILER WARNINGS
4341		4657
4342	Depending on your compiler and compiler settings, you might get no or a	4658	Depending on your compiler and compiler settings, you might get no or a
…		…
4353	maintainable.	4669	maintainable.
4354		4670
4355	And of course, some compiler warnings are just plain stupid, or simply	4671	And of course, some compiler warnings are just plain stupid, or simply
4356	wrong (because they don't actually warn about the condition their message	4672	wrong (because they don't actually warn about the condition their message
4357	seems to warn about). For example, certain older gcc versions had some	4673	seems to warn about). For example, certain older gcc versions had some
4358	warnings that resulted an extreme number of false positives. These have	4674	warnings that resulted in an extreme number of false positives. These have
4359	been fixed, but some people still insist on making code warn-free with	4675	been fixed, but some people still insist on making code warn-free with
4360	such buggy versions.	4676	such buggy versions.
4361		4677
4362	While libev is written to generate as few warnings as possible,	4678	While libev is written to generate as few warnings as possible,
4363	"warn-free" code is not a goal, and it is recommended not to build libev	4679	"warn-free" code is not a goal, and it is recommended not to build libev
…		…
4399	I suggest using suppression lists.	4715	I suggest using suppression lists.
4400		4716
4401		4717
4402	=head1 PORTABILITY NOTES	4718	=head1 PORTABILITY NOTES
4403		4719
		4720	=head2 GNU/LINUX 32 BIT LIMITATIONS
		4721
		4722	GNU/Linux is the only common platform that supports 64 bit file/large file
		4723	interfaces but I<disables> them by default.
		4724
		4725	That means that libev compiled in the default environment doesn't support
		4726	files larger than 2GiB or so, which mainly affects C<ev_stat> watchers.
		4727
		4728	Unfortunately, many programs try to work around this GNU/Linux issue
		4729	by enabling the large file API, which makes them incompatible with the
		4730	standard libev compiled for their system.
		4731
		4732	Likewise, libev cannot enable the large file API itself as this would
		4733	suddenly make it incompatible to the default compile time environment,
		4734	i.e. all programs not using special compile switches.
		4735
		4736	=head2 OS/X AND DARWIN BUGS
		4737
		4738	The whole thing is a bug if you ask me - basically any system interface
		4739	you touch is broken, whether it is locales, poll, kqueue or even the
		4740	OpenGL drivers.
		4741
		4742	=head3 C<kqueue> is buggy
		4743
		4744	The kqueue syscall is broken in all known versions - most versions support
		4745	only sockets, many support pipes.
		4746
		4747	Libev tries to work around this by not using C<kqueue> by default on this
		4748	rotten platform, but of course you can still ask for it when creating a
		4749	loop - embedding a socket-only kqueue loop into a select-based one is
		4750	probably going to work well.
		4751
		4752	=head3 C<poll> is buggy
		4753
		4754	Instead of fixing C<kqueue>, Apple replaced their (working) C<poll>
		4755	implementation by something calling C<kqueue> internally around the 10.5.6
		4756	release, so now C<kqueue> I<and> C<poll> are broken.
		4757
		4758	Libev tries to work around this by not using C<poll> by default on
		4759	this rotten platform, but of course you can still ask for it when creating
		4760	a loop.
		4761
		4762	=head3 C<select> is buggy
		4763
		4764	All that's left is C<select>, and of course Apple found a way to fuck this
		4765	one up as well: On OS/X, C<select> actively limits the number of file
		4766	descriptors you can pass in to 1024 - your program suddenly crashes when
		4767	you use more.
		4768
		4769	There is an undocumented "workaround" for this - defining
		4770	C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should>
		4771	work on OS/X.
		4772
		4773	=head2 SOLARIS PROBLEMS AND WORKAROUNDS
		4774
		4775	=head3 C<errno> reentrancy
		4776
		4777	The default compile environment on Solaris is unfortunately so
		4778	thread-unsafe that you can't even use components/libraries compiled
		4779	without C<-D_REENTRANT> in a threaded program, which, of course, isn't
		4780	defined by default. A valid, if stupid, implementation choice.
		4781
		4782	If you want to use libev in threaded environments you have to make sure
		4783	it's compiled with C<_REENTRANT> defined.
		4784
		4785	=head3 Event port backend
		4786
		4787	The scalable event interface for Solaris is called "event
		4788	ports". Unfortunately, this mechanism is very buggy in all major
		4789	releases. If you run into high CPU usage, your program freezes or you get
		4790	a large number of spurious wakeups, make sure you have all the relevant
		4791	and latest kernel patches applied. No, I don't know which ones, but there
		4792	are multiple ones to apply, and afterwards, event ports actually work
		4793	great.
		4794
		4795	If you can't get it to work, you can try running the program by setting
		4796	the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and
		4797	C<select> backends.
		4798
		4799	=head2 AIX POLL BUG
		4800
		4801	AIX unfortunately has a broken C<poll.h> header. Libev works around
		4802	this by trying to avoid the poll backend altogether (i.e. it's not even
		4803	compiled in), which normally isn't a big problem as C<select> works fine
		4804	with large bitsets on AIX, and AIX is dead anyway.
		4805
4404	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS	4806	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
		4807
		4808	=head3 General issues
4405		4809
4406	Win32 doesn't support any of the standards (e.g. POSIX) that libev	4810	Win32 doesn't support any of the standards (e.g. POSIX) that libev
4407	requires, and its I/O model is fundamentally incompatible with the POSIX	4811	requires, and its I/O model is fundamentally incompatible with the POSIX
4408	model. Libev still offers limited functionality on this platform in	4812	model. Libev still offers limited functionality on this platform in
4409	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	4813	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
4410	descriptors. This only applies when using Win32 natively, not when using	4814	descriptors. This only applies when using Win32 natively, not when using
4411	e.g. cygwin.	4815	e.g. cygwin. Actually, it only applies to the microsofts own compilers,
		4816	as every compielr comes with a slightly differently broken/incompatible
		4817	environment.
4412		4818
4413	Lifting these limitations would basically require the full	4819	Lifting these limitations would basically require the full
4414	re-implementation of the I/O system. If you are into these kinds of	4820	re-implementation of the I/O system. If you are into this kind of thing,
4415	things, then note that glib does exactly that for you in a very portable	4821	then note that glib does exactly that for you in a very portable way (note
4416	way (note also that glib is the slowest event library known to man).	4822	also that glib is the slowest event library known to man).
4417		4823
4418	There is no supported compilation method available on windows except	4824	There is no supported compilation method available on windows except
4419	embedding it into other applications.	4825	embedding it into other applications.
4420		4826
4421	Sensible signal handling is officially unsupported by Microsoft - libev	4827	Sensible signal handling is officially unsupported by Microsoft - libev
…		…
4449	you do I<not> compile the F<ev.c> or any other embedded source files!):	4855	you do I<not> compile the F<ev.c> or any other embedded source files!):
4450		4856
4451	#include "evwrap.h"	4857	#include "evwrap.h"
4452	#include "ev.c"	4858	#include "ev.c"
4453		4859
4454	=over 4
4455
4456	=item The winsocket select function	4860	=head3 The winsocket C<select> function
4457		4861
4458	The winsocket C<select> function doesn't follow POSIX in that it	4862	The winsocket C<select> function doesn't follow POSIX in that it
4459	requires socket I<handles> and not socket I<file descriptors> (it is	4863	requires socket I<handles> and not socket I<file descriptors> (it is
4460	also extremely buggy). This makes select very inefficient, and also	4864	also extremely buggy). This makes select very inefficient, and also
4461	requires a mapping from file descriptors to socket handles (the Microsoft	4865	requires a mapping from file descriptors to socket handles (the Microsoft
…		…
4470	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */	4874	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
4471		4875
4472	Note that winsockets handling of fd sets is O(n), so you can easily get a	4876	Note that winsockets handling of fd sets is O(n), so you can easily get a
4473	complexity in the O(n²) range when using win32.	4877	complexity in the O(n²) range when using win32.
4474		4878
4475	=item Limited number of file descriptors	4879	=head3 Limited number of file descriptors
4476		4880
4477	Windows has numerous arbitrary (and low) limits on things.	4881	Windows has numerous arbitrary (and low) limits on things.
4478		4882
4479	Early versions of winsocket's select only supported waiting for a maximum	4883	Early versions of winsocket's select only supported waiting for a maximum
4480	of C<64> handles (probably owning to the fact that all windows kernels	4884	of C<64> handles (probably owning to the fact that all windows kernels
…		…
4495	runtime libraries. This might get you to about C<512> or C<2048> sockets	4899	runtime libraries. This might get you to about C<512> or C<2048> sockets
4496	(depending on windows version and/or the phase of the moon). To get more,	4900	(depending on windows version and/or the phase of the moon). To get more,
4497	you need to wrap all I/O functions and provide your own fd management, but	4901	you need to wrap all I/O functions and provide your own fd management, but
4498	the cost of calling select (O(n²)) will likely make this unworkable.	4902	the cost of calling select (O(n²)) will likely make this unworkable.
4499		4903
4500	=back
4501
4502	=head2 PORTABILITY REQUIREMENTS	4904	=head2 PORTABILITY REQUIREMENTS
4503		4905
4504	In addition to a working ISO-C implementation and of course the	4906	In addition to a working ISO-C implementation and of course the
4505	backend-specific APIs, libev relies on a few additional extensions:	4907	backend-specific APIs, libev relies on a few additional extensions:
4506		4908
…		…
4512	Libev assumes not only that all watcher pointers have the same internal	4914	Libev assumes not only that all watcher pointers have the same internal
4513	structure (guaranteed by POSIX but not by ISO C for example), but it also	4915	structure (guaranteed by POSIX but not by ISO C for example), but it also
4514	assumes that the same (machine) code can be used to call any watcher	4916	assumes that the same (machine) code can be used to call any watcher
4515	callback: The watcher callbacks have different type signatures, but libev	4917	callback: The watcher callbacks have different type signatures, but libev
4516	calls them using an C<ev_watcher *> internally.	4918	calls them using an C<ev_watcher *> internally.
		4919
		4920	=item pointer accesses must be thread-atomic
		4921
		4922	Accessing a pointer value must be atomic, it must both be readable and
		4923	writable in one piece - this is the case on all current architectures.
4517		4924
4518	=item C<sig_atomic_t volatile> must be thread-atomic as well	4925	=item C<sig_atomic_t volatile> must be thread-atomic as well
4519		4926
4520	The type C<sig_atomic_t volatile> (or whatever is defined as	4927	The type C<sig_atomic_t volatile> (or whatever is defined as
4521	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different	4928	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different
…		…
4544	watchers.	4951	watchers.
4545		4952
4546	=item C<double> must hold a time value in seconds with enough accuracy	4953	=item C<double> must hold a time value in seconds with enough accuracy
4547		4954
4548	The type C<double> is used to represent timestamps. It is required to	4955	The type C<double> is used to represent timestamps. It is required to
4549	have at least 51 bits of mantissa (and 9 bits of exponent), which is good	4956	have at least 51 bits of mantissa (and 9 bits of exponent), which is
4550	enough for at least into the year 4000. This requirement is fulfilled by	4957	good enough for at least into the year 4000 with millisecond accuracy
		4958	(the design goal for libev). This requirement is overfulfilled by
4551	implementations implementing IEEE 754, which is basically all existing	4959	implementations using IEEE 754, which is basically all existing ones. With
4552	ones. With IEEE 754 doubles, you get microsecond accuracy until at least	4960	IEEE 754 doubles, you get microsecond accuracy until at least 2200.
4553	2200.
4554		4961
4555	=back	4962	=back
4556		4963
4557	If you know of other additional requirements drop me a note.	4964	If you know of other additional requirements drop me a note.
4558		4965
…		…
4628	=back	5035	=back
4629		5036
4630		5037
4631	=head1 PORTING FROM LIBEV 3.X TO 4.X	5038	=head1 PORTING FROM LIBEV 3.X TO 4.X
4632		5039
4633	The major version 4 introduced some minor incompatible changes to the API.	5040	The major version 4 introduced some incompatible changes to the API.
4634		5041
4635	At the moment, the C<ev.h> header file tries to implement superficial	5042	At the moment, the C<ev.h> header file provides compatibility definitions
4636	compatibility, so most programs should still compile. Those might be	5043	for all changes, so most programs should still compile. The compatibility
4637	removed in later versions of libev, so better update early than late.	5044	layer might be removed in later versions of libev, so better update to the
		5045	new API early than late.
4638		5046
4639	=over 4	5047	=over 4
4640		5048
4641	=item C<ev_loop_count> renamed to C<ev_iteration>	5049	=item C<EV_COMPAT3> backwards compatibility mechanism
4642		5050
4643	=item C<ev_loop_depth> renamed to C<ev_depth>	5051	The backward compatibility mechanism can be controlled by
		5052	C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING>
		5053	section.
4644		5054
4645	=item C<ev_loop_verify> renamed to C<ev_verify>	5055	=item C<ev_default_destroy> and C<ev_default_fork> have been removed
		5056
		5057	These calls can be replaced easily by their C<ev_loop_xxx> counterparts:
		5058
		5059	ev_loop_destroy (EV_DEFAULT_UC);
		5060	ev_loop_fork (EV_DEFAULT);
		5061
		5062	=item function/symbol renames
		5063
		5064	A number of functions and symbols have been renamed:
		5065
		5066	ev_loop => ev_run
		5067	EVLOOP_NONBLOCK => EVRUN_NOWAIT
		5068	EVLOOP_ONESHOT => EVRUN_ONCE
		5069
		5070	ev_unloop => ev_break
		5071	EVUNLOOP_CANCEL => EVBREAK_CANCEL
		5072	EVUNLOOP_ONE => EVBREAK_ONE
		5073	EVUNLOOP_ALL => EVBREAK_ALL
		5074
		5075	EV_TIMEOUT => EV_TIMER
		5076
		5077	ev_loop_count => ev_iteration
		5078	ev_loop_depth => ev_depth
		5079	ev_loop_verify => ev_verify
4646		5080
4647	Most functions working on C<struct ev_loop> objects don't have an	5081	Most functions working on C<struct ev_loop> objects don't have an
4648	C<ev_loop_> prefix, so it was removed. Note that C<ev_loop_fork> is	5082	C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and
		5083	associated constants have been renamed to not collide with the C<struct
		5084	ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme
		5085	as all other watcher types. Note that C<ev_loop_fork> is still called
4649	still called C<ev_loop_fork> because it would otherwise clash with the	5086	C<ev_loop_fork> because it would otherwise clash with the C<ev_fork>
4650	C<ev_fork> typedef.	5087	typedef.
4651
4652	=item C<EV_TIMEOUT> renamed to C<EV_TIMER> in C<revents>
4653
4654	This is a simple rename - all other watcher types use their name
4655	as revents flag, and now C<ev_timer> does, too.
4656
4657	Both C<EV_TIMER> and C<EV_TIMEOUT> symbols were present in 3.x versions
4658	and continue to be present for the forseeable future, so this is mostly a
4659	documentation change.
4660		5088
4661	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>	5089	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>
4662		5090
4663	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different	5091	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different
4664	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile	5092	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile
…		…
4671		5099
4672	=over 4	5100	=over 4
4673		5101
4674	=item active	5102	=item active
4675		5103
4676	A watcher is active as long as it has been started (has been attached to	5104	A watcher is active as long as it has been started and not yet stopped.
4677	an event loop) but not yet stopped (disassociated from the event loop).	5105	See L<WATCHER STATES> for details.
4678		5106
4679	=item application	5107	=item application
4680		5108
4681	In this document, an application is whatever is using libev.	5109	In this document, an application is whatever is using libev.
		5110
		5111	=item backend
		5112
		5113	The part of the code dealing with the operating system interfaces.
4682		5114
4683	=item callback	5115	=item callback
4684		5116
4685	The address of a function that is called when some event has been	5117	The address of a function that is called when some event has been
4686	detected. Callbacks are being passed the event loop, the watcher that	5118	detected. Callbacks are being passed the event loop, the watcher that
4687	received the event, and the actual event bitset.	5119	received the event, and the actual event bitset.
4688		5120
4689	=item callback invocation	5121	=item callback/watcher invocation
4690		5122
4691	The act of calling the callback associated with a watcher.	5123	The act of calling the callback associated with a watcher.
4692		5124
4693	=item event	5125	=item event
4694		5126
…		…
4713	The model used to describe how an event loop handles and processes	5145	The model used to describe how an event loop handles and processes
4714	watchers and events.	5146	watchers and events.
4715		5147
4716	=item pending	5148	=item pending
4717		5149
4718	A watcher is pending as soon as the corresponding event has been detected,	5150	A watcher is pending as soon as the corresponding event has been
4719	and stops being pending as soon as the watcher will be invoked or its	5151	detected. See L<WATCHER STATES> for details.
4720	pending status is explicitly cleared by the application.
4721
4722	A watcher can be pending, but not active. Stopping a watcher also clears
4723	its pending status.
4724		5152
4725	=item real time	5153	=item real time
4726		5154
4727	The physical time that is observed. It is apparently strictly monotonic :)	5155	The physical time that is observed. It is apparently strictly monotonic :)
4728		5156
…		…
4735	=item watcher	5163	=item watcher
4736		5164
4737	A data structure that describes interest in certain events. Watchers need	5165	A data structure that describes interest in certain events. Watchers need
4738	to be started (attached to an event loop) before they can receive events.	5166	to be started (attached to an event loop) before they can receive events.
4739		5167
4740	=item watcher invocation
4741
4742	The act of calling the callback associated with a watcher.
4743
4744	=back	5168	=back
4745		5169
4746	=head1 AUTHOR	5170	=head1 AUTHOR
4747		5171
4748	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson.	5172	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael
		5173	Magnusson and Emanuele Giaquinta.
4749		5174

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