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Revision 1.305 by root, Thu Oct 14 05:07:04 2010 UTC vs.
Revision 1.353 by root, Mon Jan 10 14:36:44 2011 UTC

…		…
26	puts ("stdin ready");	26	puts ("stdin ready");
27	// for one-shot events, one must manually stop the watcher	27	// for one-shot events, one must manually stop the watcher
28	// with its corresponding stop function.	28	// with its corresponding stop function.
29	ev_io_stop (EV_A_ w);	29	ev_io_stop (EV_A_ w);
30		30
31	// this causes all nested ev_loop's to stop iterating	31	// this causes all nested ev_run's to stop iterating
32	ev_unloop (EV_A_ EVUNLOOP_ALL);	32	ev_break (EV_A_ EVBREAK_ALL);
33	}	33	}
34		34
35	// another callback, this time for a time-out	35	// another callback, this time for a time-out
36	static void	36	static void
37	timeout_cb (EV_P_ ev_timer *w, int revents)	37	timeout_cb (EV_P_ ev_timer *w, int revents)
38	{	38	{
39	puts ("timeout");	39	puts ("timeout");
40	// this causes the innermost ev_loop to stop iterating	40	// this causes the innermost ev_run to stop iterating
41	ev_unloop (EV_A_ EVUNLOOP_ONE);	41	ev_break (EV_A_ EVBREAK_ONE);
42	}	42	}
43		43
44	int	44	int
45	main (void)	45	main (void)
46	{	46	{
47	// use the default event loop unless you have special needs	47	// use the default event loop unless you have special needs
48	struct ev_loop *loop = ev_default_loop (0);	48	struct ev_loop *loop = EV_DEFAULT;
49		49
50	// initialise an io watcher, then start it	50	// initialise an io watcher, then start it
51	// this one will watch for stdin to become readable	51	// this one will watch for stdin to become readable
52	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);	52	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);
53	ev_io_start (loop, &stdin_watcher);	53	ev_io_start (loop, &stdin_watcher);
…		…
56	// simple non-repeating 5.5 second timeout	56	// simple non-repeating 5.5 second timeout
57	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);	57	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
58	ev_timer_start (loop, &timeout_watcher);	58	ev_timer_start (loop, &timeout_watcher);
59		59
60	// now wait for events to arrive	60	// now wait for events to arrive
61	ev_loop (loop, 0);	61	ev_run (loop, 0);
62		62
63	// unloop was called, so exit	63	// unloop was called, so exit
64	return 0;	64	return 0;
65	}	65	}
66		66
…		…
77	on event-based programming, nor will it introduce event-based programming	77	on event-based programming, nor will it introduce event-based programming
78	with libev.	78	with libev.
79		79
80	Familiarity with event based programming techniques in general is assumed	80	Familiarity with event based programming techniques in general is assumed
81	throughout this document.	81	throughout this document.
		82
		83	=head1 WHAT TO READ WHEN IN A HURRY
		84
		85	This manual tries to be very detailed, but unfortunately, this also makes
		86	it very long. If you just want to know the basics of libev, I suggest
		87	reading L<ANATOMY OF A WATCHER>, then the L<EXAMPLE PROGRAM> above and
		88	look up the missing functions in L<GLOBAL FUNCTIONS> and the C<ev_io> and
		89	C<ev_timer> sections in L<WATCHER TYPES>.
82		90
83	=head1 ABOUT LIBEV	91	=head1 ABOUT LIBEV
84		92
85	Libev is an event loop: you register interest in certain events (such as a	93	Libev is an event loop: you register interest in certain events (such as a
86	file descriptor being readable or a timeout occurring), and it will manage	94	file descriptor being readable or a timeout occurring), and it will manage
…		…
124	this argument.	132	this argument.
125		133
126	=head2 TIME REPRESENTATION	134	=head2 TIME REPRESENTATION
127		135
128	Libev represents time as a single floating point number, representing	136	Libev represents time as a single floating point number, representing
129	the (fractional) number of seconds since the (POSIX) epoch (in practise	137	the (fractional) number of seconds since the (POSIX) epoch (in practice
130	somewhere near the beginning of 1970, details are complicated, don't	138	somewhere near the beginning of 1970, details are complicated, don't
131	ask). This type is called C<ev_tstamp>, which is what you should use	139	ask). This type is called C<ev_tstamp>, which is what you should use
132	too. It usually aliases to the C<double> type in C. When you need to do	140	too. It usually aliases to the C<double> type in C. When you need to do
133	any calculations on it, you should treat it as some floating point value.	141	any calculations on it, you should treat it as some floating point value.
134		142
…		…
165		173
166	=item ev_tstamp ev_time ()	174	=item ev_tstamp ev_time ()
167		175
168	Returns the current time as libev would use it. Please note that the	176	Returns the current time as libev would use it. Please note that the
169	C<ev_now> function is usually faster and also often returns the timestamp	177	C<ev_now> function is usually faster and also often returns the timestamp
170	you actually want to know.	178	you actually want to know. Also interesting is the combination of
		179	C<ev_update_now> and C<ev_now>.
171		180
172	=item ev_sleep (ev_tstamp interval)	181	=item ev_sleep (ev_tstamp interval)
173		182
174	Sleep for the given interval: The current thread will be blocked until	183	Sleep for the given interval: The current thread will be blocked until
175	either it is interrupted or the given time interval has passed. Basically	184	either it is interrupted or the given time interval has passed. Basically
…		…
192	as this indicates an incompatible change. Minor versions are usually	201	as this indicates an incompatible change. Minor versions are usually
193	compatible to older versions, so a larger minor version alone is usually	202	compatible to older versions, so a larger minor version alone is usually
194	not a problem.	203	not a problem.
195		204
196	Example: Make sure we haven't accidentally been linked against the wrong	205	Example: Make sure we haven't accidentally been linked against the wrong
197	version (note, however, that this will not detect ABI mismatches :).	206	version (note, however, that this will not detect other ABI mismatches,
		207	such as LFS or reentrancy).
198		208
199	assert (("libev version mismatch",	209	assert (("libev version mismatch",
200	ev_version_major () == EV_VERSION_MAJOR	210	ev_version_major () == EV_VERSION_MAJOR
201	&& ev_version_minor () >= EV_VERSION_MINOR));	211	&& ev_version_minor () >= EV_VERSION_MINOR));
202		212
…		…
213	assert (("sorry, no epoll, no sex",	223	assert (("sorry, no epoll, no sex",
214	ev_supported_backends () & EVBACKEND_EPOLL));	224	ev_supported_backends () & EVBACKEND_EPOLL));
215		225
216	=item unsigned int ev_recommended_backends ()	226	=item unsigned int ev_recommended_backends ()
217		227
218	Return the set of all backends compiled into this binary of libev and also	228	Return the set of all backends compiled into this binary of libev and
219	recommended for this platform. This set is often smaller than the one	229	also recommended for this platform, meaning it will work for most file
		230	descriptor types. This set is often smaller than the one returned by
220	returned by C<ev_supported_backends>, as for example kqueue is broken on	231	C<ev_supported_backends>, as for example kqueue is broken on most BSDs
221	most BSDs and will not be auto-detected unless you explicitly request it	232	and will not be auto-detected unless you explicitly request it (assuming
222	(assuming you know what you are doing). This is the set of backends that	233	you know what you are doing). This is the set of backends that libev will
223	libev will probe for if you specify no backends explicitly.	234	probe for if you specify no backends explicitly.
224		235
225	=item unsigned int ev_embeddable_backends ()	236	=item unsigned int ev_embeddable_backends ()
226		237
227	Returns the set of backends that are embeddable in other event loops. This	238	Returns the set of backends that are embeddable in other event loops. This
228	is the theoretical, all-platform, value. To find which backends	239	value is platform-specific but can include backends not available on the
229	might be supported on the current system, you would need to look at	240	current system. To find which embeddable backends might be supported on
230	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for	241	the current system, you would need to look at C<ev_embeddable_backends ()
231	recommended ones.	242	& ev_supported_backends ()>, likewise for recommended ones.
232		243
233	See the description of C<ev_embed> watchers for more info.	244	See the description of C<ev_embed> watchers for more info.
234		245
235	=item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT]	246	=item ev_set_allocator (void *(*cb)(void *ptr, long size))
236		247
237	Sets the allocation function to use (the prototype is similar - the	248	Sets the allocation function to use (the prototype is similar - the
238	semantics are identical to the C<realloc> C89/SuS/POSIX function). It is	249	semantics are identical to the C<realloc> C89/SuS/POSIX function). It is
239	used to allocate and free memory (no surprises here). If it returns zero	250	used to allocate and free memory (no surprises here). If it returns zero
240	when memory needs to be allocated (C<size != 0>), the library might abort	251	when memory needs to be allocated (C<size != 0>), the library might abort
…		…
266	}	277	}
267		278
268	...	279	...
269	ev_set_allocator (persistent_realloc);	280	ev_set_allocator (persistent_realloc);
270		281
271	=item ev_set_syserr_cb (void (*cb)(const char *msg)); [NOT REENTRANT]	282	=item ev_set_syserr_cb (void (*cb)(const char *msg))
272		283
273	Set the callback function to call on a retryable system call error (such	284	Set the callback function to call on a retryable system call error (such
274	as failed select, poll, epoll_wait). The message is a printable string	285	as failed select, poll, epoll_wait). The message is a printable string
275	indicating the system call or subsystem causing the problem. If this	286	indicating the system call or subsystem causing the problem. If this
276	callback is set, then libev will expect it to remedy the situation, no	287	callback is set, then libev will expect it to remedy the situation, no
…		…
288	}	299	}
289		300
290	...	301	...
291	ev_set_syserr_cb (fatal_error);	302	ev_set_syserr_cb (fatal_error);
292		303
		304	=item ev_feed_signal (int signum)
		305
		306	This function can be used to "simulate" a signal receive. It is completely
		307	safe to call this function at any time, from any context, including signal
		308	handlers or random threads.
		309
		310	Its main use is to customise signal handling in your process, especially
		311	in the presence of threads. For example, you could block signals
		312	by default in all threads (and specifying C<EVFLAG_NOSIGMASK> when
		313	creating any loops), and in one thread, use C<sigwait> or any other
		314	mechanism to wait for signals, then "deliver" them to libev by calling
		315	C<ev_feed_signal>.
		316
293	=back	317	=back
294		318
295	=head1 FUNCTIONS CONTROLLING THE EVENT LOOP	319	=head1 FUNCTIONS CONTROLLING EVENT LOOPS
296		320
297	An event loop is described by a C<struct ev_loop *> (the C<struct>	321	An event loop is described by a C<struct ev_loop *> (the C<struct> is
298	is I<not> optional in this case, as there is also an C<ev_loop>	322	I<not> optional in this case unless libev 3 compatibility is disabled, as
299	I<function>).	323	libev 3 had an C<ev_loop> function colliding with the struct name).
300		324
301	The library knows two types of such loops, the I<default> loop, which	325	The library knows two types of such loops, the I<default> loop, which
302	supports signals and child events, and dynamically created loops which do	326	supports child process events, and dynamically created event loops which
303	not.	327	do not.
304		328
305	=over 4	329	=over 4
306		330
307	=item struct ev_loop *ev_default_loop (unsigned int flags)	331	=item struct ev_loop *ev_default_loop (unsigned int flags)
308		332
309	This will initialise the default event loop if it hasn't been initialised	333	This returns the "default" event loop object, which is what you should
310	yet and return it. If the default loop could not be initialised, returns	334	normally use when you just need "the event loop". Event loop objects and
311	false. If it already was initialised it simply returns it (and ignores the	335	the C<flags> parameter are described in more detail in the entry for
312	flags. If that is troubling you, check C<ev_backend ()> afterwards).	336	C<ev_loop_new>.
		337
		338	If the default loop is already initialised then this function simply
		339	returns it (and ignores the flags. If that is troubling you, check
		340	C<ev_backend ()> afterwards). Otherwise it will create it with the given
		341	flags, which should almost always be C<0>, unless the caller is also the
		342	one calling C<ev_run> or otherwise qualifies as "the main program".
313		343
314	If you don't know what event loop to use, use the one returned from this	344	If you don't know what event loop to use, use the one returned from this
315	function.	345	function (or via the C<EV_DEFAULT> macro).
316		346
317	Note that this function is I<not> thread-safe, so if you want to use it	347	Note that this function is I<not> thread-safe, so if you want to use it
318	from multiple threads, you have to lock (note also that this is unlikely,	348	from multiple threads, you have to employ some kind of mutex (note also
319	as loops cannot be shared easily between threads anyway).	349	that this case is unlikely, as loops cannot be shared easily between
		350	threads anyway).
320		351
321	The default loop is the only loop that can handle C<ev_signal> and	352	The default loop is the only loop that can handle C<ev_child> watchers,
322	C<ev_child> watchers, and to do this, it always registers a handler	353	and to do this, it always registers a handler for C<SIGCHLD>. If this is
323	for C<SIGCHLD>. If this is a problem for your application you can either	354	a problem for your application you can either create a dynamic loop with
324	create a dynamic loop with C<ev_loop_new> that doesn't do that, or you	355	C<ev_loop_new> which doesn't do that, or you can simply overwrite the
325	can simply overwrite the C<SIGCHLD> signal handler I<after> calling	356	C<SIGCHLD> signal handler I<after> calling C<ev_default_init>.
326	C<ev_default_init>.	357
		358	Example: This is the most typical usage.
		359
		360	if (!ev_default_loop (0))
		361	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
		362
		363	Example: Restrict libev to the select and poll backends, and do not allow
		364	environment settings to be taken into account:
		365
		366	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
		367
		368	=item struct ev_loop *ev_loop_new (unsigned int flags)
		369
		370	This will create and initialise a new event loop object. If the loop
		371	could not be initialised, returns false.
		372
		373	This function is thread-safe, and one common way to use libev with
		374	threads is indeed to create one loop per thread, and using the default
		375	loop in the "main" or "initial" thread.
327		376
328	The flags argument can be used to specify special behaviour or specific	377	The flags argument can be used to specify special behaviour or specific
329	backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>).	378	backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>).
330		379
331	The following flags are supported:	380	The following flags are supported:
…		…
366	environment variable.	415	environment variable.
367		416
368	=item C<EVFLAG_NOINOTIFY>	417	=item C<EVFLAG_NOINOTIFY>
369		418
370	When this flag is specified, then libev will not attempt to use the	419	When this flag is specified, then libev will not attempt to use the
371	I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and	420	I<inotify> API for its C<ev_stat> watchers. Apart from debugging and
372	testing, this flag can be useful to conserve inotify file descriptors, as	421	testing, this flag can be useful to conserve inotify file descriptors, as
373	otherwise each loop using C<ev_stat> watchers consumes one inotify handle.	422	otherwise each loop using C<ev_stat> watchers consumes one inotify handle.
374		423
375	=item C<EVFLAG_SIGNALFD>	424	=item C<EVFLAG_SIGNALFD>
376		425
377	When this flag is specified, then libev will attempt to use the	426	When this flag is specified, then libev will attempt to use the
378	I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This API	427	I<signalfd> API for its C<ev_signal> (and C<ev_child>) watchers. This API
379	delivers signals synchronously, which makes it both faster and might make	428	delivers signals synchronously, which makes it both faster and might make
380	it possible to get the queued signal data. It can also simplify signal	429	it possible to get the queued signal data. It can also simplify signal
381	handling with threads, as long as you properly block signals in your	430	handling with threads, as long as you properly block signals in your
382	threads that are not interested in handling them.	431	threads that are not interested in handling them.
383		432
384	Signalfd will not be used by default as this changes your signal mask, and	433	Signalfd will not be used by default as this changes your signal mask, and
385	there are a lot of shoddy libraries and programs (glib's threadpool for	434	there are a lot of shoddy libraries and programs (glib's threadpool for
386	example) that can't properly initialise their signal masks.	435	example) that can't properly initialise their signal masks.
		436
		437	=item C<EVFLAG_NOSIGMASK>
		438
		439	When this flag is specified, then libev will avoid to modify the signal
		440	mask. Specifically, this means you ahve to make sure signals are unblocked
		441	when you want to receive them.
		442
		443	This behaviour is useful when you want to do your own signal handling, or
		444	want to handle signals only in specific threads and want to avoid libev
		445	unblocking the signals.
		446
		447	This flag's behaviour will become the default in future versions of libev.
387		448
388	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	449	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
389		450
390	This is your standard select(2) backend. Not I<completely> standard, as	451	This is your standard select(2) backend. Not I<completely> standard, as
391	libev tries to roll its own fd_set with no limits on the number of fds,	452	libev tries to roll its own fd_set with no limits on the number of fds,
…		…
427	epoll scales either O(1) or O(active_fds).	488	epoll scales either O(1) or O(active_fds).
428		489
429	The epoll mechanism deserves honorable mention as the most misdesigned	490	The epoll mechanism deserves honorable mention as the most misdesigned
430	of the more advanced event mechanisms: mere annoyances include silently	491	of the more advanced event mechanisms: mere annoyances include silently
431	dropping file descriptors, requiring a system call per change per file	492	dropping file descriptors, requiring a system call per change per file
432	descriptor (and unnecessary guessing of parameters), problems with dup and	493	descriptor (and unnecessary guessing of parameters), problems with dup,
		494	returning before the timeout value, resulting in additional iterations
		495	(and only giving 5ms accuracy while select on the same platform gives
433	so on. The biggest issue is fork races, however - if a program forks then	496	0.1ms) and so on. The biggest issue is fork races, however - if a program
434	I<both> parent and child process have to recreate the epoll set, which can	497	forks then I<both> parent and child process have to recreate the epoll
435	take considerable time (one syscall per file descriptor) and is of course	498	set, which can take considerable time (one syscall per file descriptor)
436	hard to detect.	499	and is of course hard to detect.
437		500
438	Epoll is also notoriously buggy - embedding epoll fds I<should> work, but	501	Epoll is also notoriously buggy - embedding epoll fds I<should> work, but
439	of course I<doesn't>, and epoll just loves to report events for totally	502	of course I<doesn't>, and epoll just loves to report events for totally
440	I<different> file descriptors (even already closed ones, so one cannot	503	I<different> file descriptors (even already closed ones, so one cannot
441	even remove them from the set) than registered in the set (especially	504	even remove them from the set) than registered in the set (especially
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.
445		512
446	While stopping, setting and starting an I/O watcher in the same iteration	513	While stopping, setting and starting an I/O watcher in the same iteration
447	will result in some caching, there is still a system call per such	514	will result in some caching, there is still a system call per such
448	incident (because the same I<file descriptor> could point to a different	515	incident (because the same I<file descriptor> could point to a different
449	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed	516	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed
…		…
515	=item C<EVBACKEND_PORT> (value 32, Solaris 10)	582	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
516		583
517	This uses the Solaris 10 event port mechanism. As with everything on Solaris,	584	This uses the Solaris 10 event port mechanism. As with everything on Solaris,
518	it's really slow, but it still scales very well (O(active_fds)).	585	it's really slow, but it still scales very well (O(active_fds)).
519		586
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	587	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	588	file descriptor per loop iteration. For small and medium numbers of file
526	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend	589	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend
527	might perform better.	590	might perform better.
528		591
529	On the positive side, with the exception of the spurious readiness	592	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	593	specification in all tests and is fully embeddable, which is a rare feat
532	OS-specific backends (I vastly prefer correctness over speed hacks).	594	among the OS-specific backends (I vastly prefer correctness over speed
		595	hacks).
		596
		597	On the negative side, the interface is I<bizarre> - so bizarre that
		598	even sun itself gets it wrong in their code examples: The event polling
		599	function sometimes returning events to the caller even though an error
		600	occurred, but with no indication whether it has done so or not (yes, it's
		601	even documented that way) - deadly for edge-triggered interfaces where
		602	you absolutely have to know whether an event occurred or not because you
		603	have to re-arm the watcher.
		604
		605	Fortunately libev seems to be able to work around these idiocies.
533		606
534	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as	607	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as
535	C<EVBACKEND_POLL>.	608	C<EVBACKEND_POLL>.
536		609
537	=item C<EVBACKEND_ALL>	610	=item C<EVBACKEND_ALL>
538		611
539	Try all backends (even potentially broken ones that wouldn't be tried	612	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	613	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as
541	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.	614	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.
542		615
543	It is definitely not recommended to use this flag.	616	It is definitely not recommended to use this flag, use whatever
		617	C<ev_recommended_backends ()> returns, or simply do not specify a backend
		618	at all.
		619
		620	=item C<EVBACKEND_MASK>
		621
		622	Not a backend at all, but a mask to select all backend bits from a
		623	C<flags> value, in case you want to mask out any backends from a flags
		624	value (e.g. when modifying the C<LIBEV_FLAGS> environment variable).
544		625
545	=back	626	=back
546		627
547	If one or more of the backend flags are or'ed into the flags value,	628	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	629	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	630	here). If none are specified, all backends in C<ev_recommended_backends
550	()> will be tried.	631	()> will be tried.
551		632
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.	633	Example: Try to create a event loop that uses epoll and nothing else.
579		634
580	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	635	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
581	if (!epoller)	636	if (!epoller)
582	fatal ("no epoll found here, maybe it hides under your chair");	637	fatal ("no epoll found here, maybe it hides under your chair");
583		638
		639	Example: Use whatever libev has to offer, but make sure that kqueue is
		640	used if available.
		641
		642	struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE);
		643
584	=item ev_default_destroy ()	644	=item ev_loop_destroy (loop)
585		645
586	Destroys the default loop (frees all memory and kernel state etc.). None	646	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	647	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	648	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,	649	responsibility to either stop all watchers cleanly yourself I<before>
590	or cope with the fact afterwards (which is usually the easiest thing, you	650	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).	651	the easiest thing, you can just ignore the watchers and/or C<free ()> them
		652	for example).
592		653
593	Note that certain global state, such as signal state (and installed signal	654	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	655	handlers), will not be freed by this function, and related watchers (such
595	as signal and child watchers) would need to be stopped manually.	656	as signal and child watchers) would need to be stopped manually.
596		657
597	In general it is not advisable to call this function except in the	658	This function is normally used on loop objects allocated by
598	rare occasion where you really need to free e.g. the signal handling	659	C<ev_loop_new>, but it can also be used on the default loop returned by
		660	C<ev_default_loop>, in which case it is not thread-safe.
		661
		662	Note that it is not advisable to call this function on the default loop
		663	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	664	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>.	665	and C<ev_loop_destroy>.
601		666
602	=item ev_loop_destroy (loop)	667	=item ev_loop_fork (loop)
603		668
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	669	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	670	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	671	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	672	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	673	child before resuming or calling C<ev_run>.
614	functions, and it will only take effect at the next C<ev_loop> iteration.
615		674
616	Again, you I<have> to call it on I<any> loop that you want to re-use after	675	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	676	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	677	because some kernel interfaces *cough* I<kqueue> *cough* do funny things
619	during fork.	678	during fork.
620		679
621	On the other hand, you only need to call this function in the child	680	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	681	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	682	you just fork+exec or create a new loop in the child, you don't have to
624	it at all.	683	call it at all (in fact, C<epoll> is so badly broken that it makes a
		684	difference, but libev will usually detect this case on its own and do a
		685	costly reset of the backend).
625		686
626	The function itself is quite fast and it's usually not a problem to call	687	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	688	it just in case after a fork.
628	quite nicely into a call to C<pthread_atfork>:
629		689
		690	Example: Automate calling C<ev_loop_fork> on the default loop when
		691	using pthreads.
		692
		693	static void
		694	post_fork_child (void)
		695	{
		696	ev_loop_fork (EV_DEFAULT);
		697	}
		698
		699	...
630	pthread_atfork (0, 0, ev_default_fork);	700	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		701
639	=item int ev_is_default_loop (loop)	702	=item int ev_is_default_loop (loop)
640		703
641	Returns true when the given loop is, in fact, the default loop, and false	704	Returns true when the given loop is, in fact, the default loop, and false
642	otherwise.	705	otherwise.
643		706
644	=item unsigned int ev_iteration (loop)	707	=item unsigned int ev_iteration (loop)
645		708
646	Returns the current iteration count for the loop, which is identical to	709	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	710	to the number of times libev did poll for new events. It starts at C<0>
648	happily wraps around with enough iterations.	711	and happily wraps around with enough iterations.
649		712
650	This value can sometimes be useful as a generation counter of sorts (it	713	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	714	"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	715	C<ev_prepare> and C<ev_check> calls - and is incremented between the
653	prepare and check phases.	716	prepare and check phases.
654		717
655	=item unsigned int ev_depth (loop)	718	=item unsigned int ev_depth (loop)
656		719
657	Returns the number of times C<ev_loop> was entered minus the number of	720	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.	721	times C<ev_run> was exited normally, in other words, the recursion depth.
659		722
660	Outside C<ev_loop>, this number is zero. In a callback, this number is	723	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),	724	C<1>, unless C<ev_run> was invoked recursively (or from another thread),
662	in which case it is higher.	725	in which case it is higher.
663		726
664	Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread	727	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	728	throwing an exception etc.), doesn't count as "exit" - consider this
666	ungentleman behaviour unless it's really convenient.	729	as a hint to avoid such ungentleman-like behaviour unless it's really
		730	convenient, in which case it is fully supported.
667		731
668	=item unsigned int ev_backend (loop)	732	=item unsigned int ev_backend (loop)
669		733
670	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	734	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
671	use.	735	use.
…		…
680		744
681	=item ev_now_update (loop)	745	=item ev_now_update (loop)
682		746
683	Establishes the current time by querying the kernel, updating the time	747	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	748	returned by C<ev_now ()> in the progress. This is a costly operation and
685	is usually done automatically within C<ev_loop ()>.	749	is usually done automatically within C<ev_run ()>.
686		750
687	This function is rarely useful, but when some event callback runs for a	751	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	752	very long time without entering the event loop, updating libev's idea of
689	the current time is a good idea.	753	the current time is a good idea.
690		754
…		…
692		756
693	=item ev_suspend (loop)	757	=item ev_suspend (loop)
694		758
695	=item ev_resume (loop)	759	=item ev_resume (loop)
696		760
697	These two functions suspend and resume a loop, for use when the loop is	761	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.	762	loop is not used for a while and timeouts should not be processed.
699		763
700	A typical use case would be an interactive program such as a game: When	764	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	765	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	766	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>	767	the program was suspended. This can be achieved by calling C<ev_suspend>
…		…
714	without a previous call to C<ev_suspend>.	778	without a previous call to C<ev_suspend>.
715		779
716	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the	780	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the
717	event loop time (see C<ev_now_update>).	781	event loop time (see C<ev_now_update>).
718		782
719	=item ev_loop (loop, int flags)	783	=item ev_run (loop, int flags)
720		784
721	Finally, this is it, the event handler. This function usually is called	785	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	786	after you have initialised all your watchers and you want to start
723	handling events.	787	handling events. It will ask the operating system for any new events, call
		788	the watcher callbacks, an then repeat the whole process indefinitely: This
		789	is why event loops are called I<loops>.
724		790
725	If the flags argument is specified as C<0>, it will not return until	791	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.	792	until either no event watchers are active anymore or C<ev_break> was
		793	called.
727		794
728	Please note that an explicit C<ev_unloop> is usually better than	795	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	796	relying on all watchers to be stopped when deciding when a program has
730	finished (especially in interactive programs), but having a program	797	finished (especially in interactive programs), but having a program
731	that automatically loops as long as it has to and no longer by virtue	798	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	799	of relying on its watchers stopping correctly, that is truly a thing of
733	beauty.	800	beauty.
734		801
		802	This function is also I<mostly> exception-safe - you can break out of
		803	a C<ev_run> call by calling C<longjmp> in a callback, throwing a C++
		804	exception and so on. This does not decrement the C<ev_depth> value, nor
		805	will it clear any outstanding C<EVBREAK_ONE> breaks.
		806
735	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle	807	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	808	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	809	block your process in case there are no events and will return after one
738	the loop.	810	iteration of the loop. This is sometimes useful to poll and handle new
		811	events while doing lengthy calculations, to keep the program responsive.
739		812
740	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if	813	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	814	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	815	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	816	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	817	user-registered callback will be called), and will return after one
745	iteration of the loop.	818	iteration of the loop.
746		819
747	This is useful if you are waiting for some external event in conjunction	820	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	821	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	822	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.	823	usually a better approach for this kind of thing.
751		824
752	Here are the gory details of what C<ev_loop> does:	825	Here are the gory details of what C<ev_run> does:
753		826
		827	- Increment loop depth.
		828	- Reset the ev_break status.
754	- Before the first iteration, call any pending watchers.	829	- Before the first iteration, call any pending watchers.
		830	LOOP:
755	* If EVFLAG_FORKCHECK was used, check for a fork.	831	- If EVFLAG_FORKCHECK was used, check for a fork.
756	- If a fork was detected (by any means), queue and call all fork watchers.	832	- If a fork was detected (by any means), queue and call all fork watchers.
757	- Queue and call all prepare watchers.	833	- Queue and call all prepare watchers.
		834	- If ev_break was called, goto FINISH.
758	- If we have been forked, detach and recreate the kernel state	835	- If we have been forked, detach and recreate the kernel state
759	as to not disturb the other process.	836	as to not disturb the other process.
760	- Update the kernel state with all outstanding changes.	837	- Update the kernel state with all outstanding changes.
761	- Update the "event loop time" (ev_now ()).	838	- Update the "event loop time" (ev_now ()).
762	- Calculate for how long to sleep or block, if at all	839	- Calculate for how long to sleep or block, if at all
763	(active idle watchers, EVLOOP_NONBLOCK or not having	840	(active idle watchers, EVRUN_NOWAIT or not having
764	any active watchers at all will result in not sleeping).	841	any active watchers at all will result in not sleeping).
765	- Sleep if the I/O and timer collect interval say so.	842	- Sleep if the I/O and timer collect interval say so.
		843	- Increment loop iteration counter.
766	- Block the process, waiting for any events.	844	- Block the process, waiting for any events.
767	- Queue all outstanding I/O (fd) events.	845	- Queue all outstanding I/O (fd) events.
768	- Update the "event loop time" (ev_now ()), and do time jump adjustments.	846	- Update the "event loop time" (ev_now ()), and do time jump adjustments.
769	- Queue all expired timers.	847	- Queue all expired timers.
770	- Queue all expired periodics.	848	- Queue all expired periodics.
771	- Unless any events are pending now, queue all idle watchers.	849	- Queue all idle watchers with priority higher than that of pending events.
772	- Queue all check watchers.	850	- Queue all check watchers.
773	- Call all queued watchers in reverse order (i.e. check watchers first).	851	- 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	852	Signals and child watchers are implemented as I/O watchers, and will
775	be handled here by queueing them when their watcher gets executed.	853	be handled here by queueing them when their watcher gets executed.
776	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	854	- If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT
777	were used, or there are no active watchers, return, otherwise	855	were used, or there are no active watchers, goto FINISH, otherwise
778	continue with step *.	856	continue with step LOOP.
		857	FINISH:
		858	- Reset the ev_break status iff it was EVBREAK_ONE.
		859	- Decrement the loop depth.
		860	- Return.
779		861
780	Example: Queue some jobs and then loop until no events are outstanding	862	Example: Queue some jobs and then loop until no events are outstanding
781	anymore.	863	anymore.
782		864
783	... queue jobs here, make sure they register event watchers as long	865	... 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..)	866	... as they still have work to do (even an idle watcher will do..)
785	ev_loop (my_loop, 0);	867	ev_run (my_loop, 0);
786	... jobs done or somebody called unloop. yeah!	868	... jobs done or somebody called unloop. yeah!
787		869
788	=item ev_unloop (loop, how)	870	=item ev_break (loop, how)
789		871
790	Can be used to make a call to C<ev_loop> return early (but only after it	872	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	873	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	874	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.	875	C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return.
794		876
795	This "unloop state" will be cleared when entering C<ev_loop> again.	877	This "break state" will be cleared on the next call to C<ev_run>.
796		878
797	It is safe to call C<ev_unloop> from outside any C<ev_loop> calls.	879	It is safe to call C<ev_break> from outside any C<ev_run> calls, too, in
		880	which case it will have no effect.
798		881
799	=item ev_ref (loop)	882	=item ev_ref (loop)
800		883
801	=item ev_unref (loop)	884	=item ev_unref (loop)
802		885
803	Ref/unref can be used to add or remove a reference count on the event	886	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	887	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.	888	count is nonzero, C<ev_run> will not return on its own.
806		889
807	This is useful when you have a watcher that you never intend to	890	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	891	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>	892	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>
810	before stopping it.	893	before stopping it.
811		894
812	As an example, libev itself uses this for its internal signal pipe: It	895	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	896	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	897	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	898	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	899	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	900	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	901	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>	902	(e.g. non-repeating timers) in which case you have to C<ev_ref>
820	in the callback).	903	in the callback).
821		904
822	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	905	Example: Create a signal watcher, but keep it from keeping C<ev_run>
823	running when nothing else is active.	906	running when nothing else is active.
824		907
825	ev_signal exitsig;	908	ev_signal exitsig;
826	ev_signal_init (&exitsig, sig_cb, SIGINT);	909	ev_signal_init (&exitsig, sig_cb, SIGINT);
827	ev_signal_start (loop, &exitsig);	910	ev_signal_start (loop, &exitsig);
828	evf_unref (loop);	911	ev_unref (loop);
829		912
830	Example: For some weird reason, unregister the above signal handler again.	913	Example: For some weird reason, unregister the above signal handler again.
831		914
832	ev_ref (loop);	915	ev_ref (loop);
833	ev_signal_stop (loop, &exitsig);	916	ev_signal_stop (loop, &exitsig);
…		…
890	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);	973	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);
891		974
892	=item ev_invoke_pending (loop)	975	=item ev_invoke_pending (loop)
893		976
894	This call will simply invoke all pending watchers while resetting their	977	This call will simply invoke all pending watchers while resetting their
895	pending state. Normally, C<ev_loop> does this automatically when required,	978	pending state. Normally, C<ev_run> does this automatically when required,
896	but when overriding the invoke callback this call comes handy.	979	but when overriding the invoke callback this call comes handy. This
		980	function can be invoked from a watcher - this can be useful for example
		981	when you want to do some lengthy calculation and want to pass further
		982	event handling to another thread (you still have to make sure only one
		983	thread executes within C<ev_invoke_pending> or C<ev_run> of course).
897		984
898	=item int ev_pending_count (loop)	985	=item int ev_pending_count (loop)
899		986
900	Returns the number of pending watchers - zero indicates that no watchers	987	Returns the number of pending watchers - zero indicates that no watchers
901	are pending.	988	are pending.
902		989
903	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))	990	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))
904		991
905	This overrides the invoke pending functionality of the loop: Instead of	992	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	993	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	994	this callback instead. This is useful, for example, when you want to
908	invoke the actual watchers inside another context (another thread etc.).	995	invoke the actual watchers inside another context (another thread etc.).
909		996
910	If you want to reset the callback, use C<ev_invoke_pending> as new	997	If you want to reset the callback, use C<ev_invoke_pending> as new
911	callback.	998	callback.
…		…
914		1001
915	Sometimes you want to share the same loop between multiple threads. This	1002	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	1003	can be done relatively simply by putting mutex_lock/unlock calls around
917	each call to a libev function.	1004	each call to a libev function.
918		1005
919	However, C<ev_loop> can run an indefinite time, so it is not feasible to	1006	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	1007	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>	1008	loop via C<ev_break> and C<av_async_send>, another way is to set these
922	and I<acquire> callbacks on the loop.	1009	I<release> and I<acquire> callbacks on the loop.
923		1010
924	When set, then C<release> will be called just before the thread is	1011	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	1012	suspended waiting for new events, and C<acquire> is called just
926	afterwards.	1013	afterwards.
927		1014
…		…
930		1017
931	While event loop modifications are allowed between invocations of	1018	While event loop modifications are allowed between invocations of
932	C<release> and C<acquire> (that's their only purpose after all), no	1019	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	1020	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	1021	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	1022	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.	1023	to take note of any changes you made.
937		1024
938	In theory, threads executing C<ev_loop> will be async-cancel safe between	1025	In theory, threads executing C<ev_run> will be async-cancel safe between
939	invocations of C<release> and C<acquire>.	1026	invocations of C<release> and C<acquire>.
940		1027
941	See also the locking example in the C<THREADS> section later in this	1028	See also the locking example in the C<THREADS> section later in this
942	document.	1029	document.
943		1030
944	=item ev_set_userdata (loop, void *data)	1031	=item ev_set_userdata (loop, void *data)
945		1032
946	=item ev_userdata (loop)	1033	=item void *ev_userdata (loop)
947		1034
948	Set and retrieve a single C<void *> associated with a loop. When	1035	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	1036	C<ev_set_userdata> has never been called, then C<ev_userdata> returns
950	C<0.>	1037	C<0>.
951		1038
952	These two functions can be used to associate arbitrary data with a loop,	1039	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	1040	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	1041	C<acquire> callbacks described above, but of course can be (ab-)used for
955	any other purpose as well.	1042	any other purpose as well.
956		1043
957	=item ev_loop_verify (loop)	1044	=item ev_verify (loop)
958		1045
959	This function only does something when C<EV_VERIFY> support has been	1046	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	1047	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	1048	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	1049	is found to be inconsistent, it will print an error message to standard
…		…
973		1060
974	In the following description, uppercase C<TYPE> in names stands for the	1061	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	1062	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.	1063	watchers and C<ev_io_start> for I/O watchers.
977		1064
978	A watcher is a structure that you create and register to record your	1065	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	1066	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:	1067	to wait for STDIN to become readable, you would create an C<ev_io> watcher
		1068	for that:
981		1069
982	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)	1070	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)
983	{	1071	{
984	ev_io_stop (w);	1072	ev_io_stop (w);
985	ev_unloop (loop, EVUNLOOP_ALL);	1073	ev_break (loop, EVBREAK_ALL);
986	}	1074	}
987		1075
988	struct ev_loop *loop = ev_default_loop (0);	1076	struct ev_loop *loop = ev_default_loop (0);
989		1077
990	ev_io stdin_watcher;	1078	ev_io stdin_watcher;
991		1079
992	ev_init (&stdin_watcher, my_cb);	1080	ev_init (&stdin_watcher, my_cb);
993	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	1081	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
994	ev_io_start (loop, &stdin_watcher);	1082	ev_io_start (loop, &stdin_watcher);
995		1083
996	ev_loop (loop, 0);	1084	ev_run (loop, 0);
997		1085
998	As you can see, you are responsible for allocating the memory for your	1086	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	1087	watcher structures (and it is I<usually> a bad idea to do this on the
1000	stack).	1088	stack).
1001		1089
1002	Each watcher has an associated watcher structure (called C<struct ev_TYPE>	1090	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).	1091	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).
1004		1092
1005	Each watcher structure must be initialised by a call to C<ev_init	1093	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	1094	*, 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	1095	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	1096	time the event loop detects that the file descriptor given is readable
1009	is readable and/or writable).	1097	and/or writable).
1010		1098
1011	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>	1099	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	1100	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<<	1101	is also a macro to combine initialisation and setting in one call: C<<
1014	ev_TYPE_init (watcher *, callback, ...) >>.	1102	ev_TYPE_init (watcher *, callback, ...) >>.
…		…
1065		1153
1066	=item C<EV_PREPARE>	1154	=item C<EV_PREPARE>
1067		1155
1068	=item C<EV_CHECK>	1156	=item C<EV_CHECK>
1069		1157
1070	All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts	1158	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	1159	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	1160	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	1161	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	1162	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	1163	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
1076	C<ev_loop> from blocking).	1164	C<ev_run> from blocking).
1077		1165
1078	=item C<EV_EMBED>	1166	=item C<EV_EMBED>
1079		1167
1080	The embedded event loop specified in the C<ev_embed> watcher needs attention.	1168	The embedded event loop specified in the C<ev_embed> watcher needs attention.
1081		1169
1082	=item C<EV_FORK>	1170	=item C<EV_FORK>
1083		1171
1084	The event loop has been resumed in the child process after fork (see	1172	The event loop has been resumed in the child process after fork (see
1085	C<ev_fork>).	1173	C<ev_fork>).
		1174
		1175	=item C<EV_CLEANUP>
		1176
		1177	The event loop is about to be destroyed (see C<ev_cleanup>).
1086		1178
1087	=item C<EV_ASYNC>	1179	=item C<EV_ASYNC>
1088		1180
1089	The given async watcher has been asynchronously notified (see C<ev_async>).	1181	The given async watcher has been asynchronously notified (see C<ev_async>).
1090		1182
…		…
1262		1354
1263	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related	1355	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related
1264	functions that do not need a watcher.	1356	functions that do not need a watcher.
1265		1357
1266	=back	1358	=back
1267
1268		1359
1269	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	1360	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
1270		1361
1271	Each watcher has, by default, a member C<void *data> that you can change	1362	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	1363	and read at any time: libev will completely ignore it. This can be used
…		…
1328	t2_cb (EV_P_ ev_timer *w, int revents)	1419	t2_cb (EV_P_ ev_timer *w, int revents)
1329	{	1420	{
1330	struct my_biggy big = (struct my_biggy *)	1421	struct my_biggy big = (struct my_biggy *)
1331	(((char *)w) - offsetof (struct my_biggy, t2));	1422	(((char *)w) - offsetof (struct my_biggy, t2));
1332	}	1423	}
		1424
		1425	=head2 WATCHER STATES
		1426
		1427	There are various watcher states mentioned throughout this manual -
		1428	active, pending and so on. In this section these states and the rules to
		1429	transition between them will be described in more detail - and while these
		1430	rules might look complicated, they usually do "the right thing".
		1431
		1432	=over 4
		1433
		1434	=item initialiased
		1435
		1436	Before a watcher can be registered with the event looop it has to be
		1437	initialised. This can be done with a call to C<ev_TYPE_init>, or calls to
		1438	C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function.
		1439
		1440	In this state it is simply some block of memory that is suitable for use
		1441	in an event loop. It can be moved around, freed, reused etc. at will.
		1442
		1443	=item started/running/active
		1444
		1445	Once a watcher has been started with a call to C<ev_TYPE_start> it becomes
		1446	property of the event loop, and is actively waiting for events. While in
		1447	this state it cannot be accessed (except in a few documented ways), moved,
		1448	freed or anything else - the only legal thing is to keep a pointer to it,
		1449	and call libev functions on it that are documented to work on active watchers.
		1450
		1451	=item pending
		1452
		1453	If a watcher is active and libev determines that an event it is interested
		1454	in has occurred (such as a timer expiring), it will become pending. It will
		1455	stay in this pending state until either it is stopped or its callback is
		1456	about to be invoked, so it is not normally pending inside the watcher
		1457	callback.
		1458
		1459	The watcher might or might not be active while it is pending (for example,
		1460	an expired non-repeating timer can be pending but no longer active). If it
		1461	is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>),
		1462	but it is still property of the event loop at this time, so cannot be
		1463	moved, freed or reused. And if it is active the rules described in the
		1464	previous item still apply.
		1465
		1466	It is also possible to feed an event on a watcher that is not active (e.g.
		1467	via C<ev_feed_event>), in which case it becomes pending without being
		1468	active.
		1469
		1470	=item stopped
		1471
		1472	A watcher can be stopped implicitly by libev (in which case it might still
		1473	be pending), or explicitly by calling its C<ev_TYPE_stop> function. The
		1474	latter will clear any pending state the watcher might be in, regardless
		1475	of whether it was active or not, so stopping a watcher explicitly before
		1476	freeing it is often a good idea.
		1477
		1478	While stopped (and not pending) the watcher is essentially in the
		1479	initialised state, that is it can be reused, moved, modified in any way
		1480	you wish.
		1481
		1482	=back
1333		1483
1334	=head2 WATCHER PRIORITY MODELS	1484	=head2 WATCHER PRIORITY MODELS
1335		1485
1336	Many event loops support I<watcher priorities>, which are usually small	1486	Many event loops support I<watcher priorities>, which are usually small
1337	integers that influence the ordering of event callback invocation	1487	integers that influence the ordering of event callback invocation
…		…
1622	...	1772	...
1623	struct ev_loop *loop = ev_default_init (0);	1773	struct ev_loop *loop = ev_default_init (0);
1624	ev_io stdin_readable;	1774	ev_io stdin_readable;
1625	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1775	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1626	ev_io_start (loop, &stdin_readable);	1776	ev_io_start (loop, &stdin_readable);
1627	ev_loop (loop, 0);	1777	ev_run (loop, 0);
1628		1778
1629		1779
1630	=head2 C<ev_timer> - relative and optionally repeating timeouts	1780	=head2 C<ev_timer> - relative and optionally repeating timeouts
1631		1781
1632	Timer watchers are simple relative timers that generate an event after a	1782	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	1791	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	1792	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	1793	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	1794	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	1795	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).	1796	no longer true when a callback calls C<ev_run> recursively).
1647		1797
1648	=head3 Be smart about timeouts	1798	=head3 Be smart about timeouts
1649		1799
1650	Many real-world problems involve some kind of timeout, usually for error	1800	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,	1801	recovery. A typical example is an HTTP request - if the other side hangs,
…		…
1822		1972
1823	=head3 The special problem of time updates	1973	=head3 The special problem of time updates
1824		1974
1825	Establishing the current time is a costly operation (it usually takes at	1975	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	1976	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	1977	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	1978	growing difference between C<ev_now ()> and C<ev_time ()> when handling
1829	lots of events in one iteration.	1979	lots of events in one iteration.
1830		1980
1831	The relative timeouts are calculated relative to the C<ev_now ()>	1981	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	1982	time. This is usually the right thing as this timestamp refers to the time
…		…
1949	}	2099	}
1950		2100
1951	ev_timer mytimer;	2101	ev_timer mytimer;
1952	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	2102	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1953	ev_timer_again (&mytimer); /* start timer */	2103	ev_timer_again (&mytimer); /* start timer */
1954	ev_loop (loop, 0);	2104	ev_run (loop, 0);
1955		2105
1956	// and in some piece of code that gets executed on any "activity":	2106	// and in some piece of code that gets executed on any "activity":
1957	// reset the timeout to start ticking again at 10 seconds	2107	// reset the timeout to start ticking again at 10 seconds
1958	ev_timer_again (&mytimer);	2108	ev_timer_again (&mytimer);
1959		2109
…		…
1985		2135
1986	As with timers, the callback is guaranteed to be invoked only when the	2136	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	2137	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	2138	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	2139	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).	2140	(but this is no longer true when a callback calls C<ev_run> recursively).
1991		2141
1992	=head3 Watcher-Specific Functions and Data Members	2142	=head3 Watcher-Specific Functions and Data Members
1993		2143
1994	=over 4	2144	=over 4
1995		2145
…		…
2156		2306
2157	=head2 C<ev_signal> - signal me when a signal gets signalled!	2307	=head2 C<ev_signal> - signal me when a signal gets signalled!
2158		2308
2159	Signal watchers will trigger an event when the process receives a specific	2309	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	2310	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	2311	will try its best to deliver signals synchronously, i.e. as part of the
2162	normal event processing, like any other event.	2312	normal event processing, like any other event.
2163		2313
2164	If you want signals to be delivered truly asynchronously, just use	2314	If you want signals to be delivered truly asynchronously, just use
2165	C<sigaction> as you would do without libev and forget about sharing	2315	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	2316	the signal. You can even use C<ev_async> from a signal handler to
…		…
2209		2359
2210	So I can't stress this enough: I<If you do not reset your signal mask when	2360	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	2361	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.	2362	is not a libev-specific thing, this is true for most event libraries.
2213		2363
		2364	=head3 The special problem of threads signal handling
		2365
		2366	POSIX threads has problematic signal handling semantics, specifically,
		2367	a lot of functionality (sigfd, sigwait etc.) only really works if all
		2368	threads in a process block signals, which is hard to achieve.
		2369
		2370	When you want to use sigwait (or mix libev signal handling with your own
		2371	for the same signals), you can tackle this problem by globally blocking
		2372	all signals before creating any threads (or creating them with a fully set
		2373	sigprocmask) and also specifying the C<EVFLAG_NOSIGMASK> when creating
		2374	loops. Then designate one thread as "signal receiver thread" which handles
		2375	these signals. You can pass on any signals that libev might be interested
		2376	in by calling C<ev_feed_signal>.
		2377
2214	=head3 Watcher-Specific Functions and Data Members	2378	=head3 Watcher-Specific Functions and Data Members
2215		2379
2216	=over 4	2380	=over 4
2217		2381
2218	=item ev_signal_init (ev_signal *, callback, int signum)	2382	=item ev_signal_init (ev_signal *, callback, int signum)
…		…
2233	Example: Try to exit cleanly on SIGINT.	2397	Example: Try to exit cleanly on SIGINT.
2234		2398
2235	static void	2399	static void
2236	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)	2400	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)
2237	{	2401	{
2238	ev_unloop (loop, EVUNLOOP_ALL);	2402	ev_break (loop, EVBREAK_ALL);
2239	}	2403	}
2240		2404
2241	ev_signal signal_watcher;	2405	ev_signal signal_watcher;
2242	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	2406	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
2243	ev_signal_start (loop, &signal_watcher);	2407	ev_signal_start (loop, &signal_watcher);
…		…
2629		2793
2630	Prepare and check watchers are usually (but not always) used in pairs:	2794	Prepare and check watchers are usually (but not always) used in pairs:
2631	prepare watchers get invoked before the process blocks and check watchers	2795	prepare watchers get invoked before the process blocks and check watchers
2632	afterwards.	2796	afterwards.
2633		2797
2634	You I<must not> call C<ev_loop> or similar functions that enter	2798	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>	2799	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	2800	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	2801	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,	2802	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	2803	C<ev_check> so if you have one watcher of each kind they will always be
…		…
2807		2971
2808	if (timeout >= 0)	2972	if (timeout >= 0)
2809	// create/start timer	2973	// create/start timer
2810		2974
2811	// poll	2975	// poll
2812	ev_loop (EV_A_ 0);	2976	ev_run (EV_A_ 0);
2813		2977
2814	// stop timer again	2978	// stop timer again
2815	if (timeout >= 0)	2979	if (timeout >= 0)
2816	ev_timer_stop (EV_A_ &to);	2980	ev_timer_stop (EV_A_ &to);
2817		2981
…		…
2895	if you do not want that, you need to temporarily stop the embed watcher).	3059	if you do not want that, you need to temporarily stop the embed watcher).
2896		3060
2897	=item ev_embed_sweep (loop, ev_embed *)	3061	=item ev_embed_sweep (loop, ev_embed *)
2898		3062
2899	Make a single, non-blocking sweep over the embedded loop. This works	3063	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	3064	similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most
2901	appropriate way for embedded loops.	3065	appropriate way for embedded loops.
2902		3066
2903	=item struct ev_loop *other [read-only]	3067	=item struct ev_loop *other [read-only]
2904		3068
2905	The embedded event loop.	3069	The embedded event loop.
…		…
2991	disadvantage of having to use multiple event loops (which do not support	3155	disadvantage of having to use multiple event loops (which do not support
2992	signal watchers).	3156	signal watchers).
2993		3157
2994	When this is not possible, or you want to use the default loop for	3158	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	3159	other reasons, then in the process that wants to start "fresh", call
2996	C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying	3160	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	3161	Destroying the default loop will "orphan" (not stop) all registered
2998	have to be careful not to execute code that modifies those watchers. Note	3162	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.	3163	those watchers. Note also that in that case, you have to re-register any
		3164	signal watchers.
3000		3165
3001	=head3 Watcher-Specific Functions and Data Members	3166	=head3 Watcher-Specific Functions and Data Members
3002		3167
3003	=over 4	3168	=over 4
3004		3169
3005	=item ev_fork_init (ev_signal *, callback)	3170	=item ev_fork_init (ev_fork *, callback)
3006		3171
3007	Initialises and configures the fork watcher - it has no parameters of any	3172	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,	3173	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
3009	believe me.	3174	really.
3010		3175
3011	=back	3176	=back
3012		3177
3013		3178
		3179	=head2 C<ev_cleanup> - even the best things end
		3180
		3181	Cleanup watchers are called just before the event loop is being destroyed
		3182	by a call to C<ev_loop_destroy>.
		3183
		3184	While there is no guarantee that the event loop gets destroyed, cleanup
		3185	watchers provide a convenient method to install cleanup hooks for your
		3186	program, worker threads and so on - you just to make sure to destroy the
		3187	loop when you want them to be invoked.
		3188
		3189	Cleanup watchers are invoked in the same way as any other watcher. Unlike
		3190	all other watchers, they do not keep a reference to the event loop (which
		3191	makes a lot of sense if you think about it). Like all other watchers, you
		3192	can call libev functions in the callback, except C<ev_cleanup_start>.
		3193
		3194	=head3 Watcher-Specific Functions and Data Members
		3195
		3196	=over 4
		3197
		3198	=item ev_cleanup_init (ev_cleanup *, callback)
		3199
		3200	Initialises and configures the cleanup watcher - it has no parameters of
		3201	any kind. There is a C<ev_cleanup_set> macro, but using it is utterly
		3202	pointless, I assure you.
		3203
		3204	=back
		3205
		3206	Example: Register an atexit handler to destroy the default loop, so any
		3207	cleanup functions are called.
		3208
		3209	static void
		3210	program_exits (void)
		3211	{
		3212	ev_loop_destroy (EV_DEFAULT_UC);
		3213	}
		3214
		3215	...
		3216	atexit (program_exits);
		3217
		3218
3014	=head2 C<ev_async> - how to wake up an event loop	3219	=head2 C<ev_async> - how to wake up an event loop
3015		3220
3016	In general, you cannot use an C<ev_loop> from multiple threads or other	3221	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	3222	asynchronous sources such as signal handlers (as opposed to multiple event
3018	loops - those are of course safe to use in different threads).	3223	loops - those are of course safe to use in different threads).
3019		3224
3020	Sometimes, however, you need to wake up an event loop you do not control,	3225	Sometimes, however, you need to wake up an event loop you do not control,
3021	for example because it belongs to another thread. This is what C<ev_async>	3226	for example because it belongs to another thread. This is what C<ev_async>
…		…
3023	it by calling C<ev_async_send>, which is thread- and signal safe.	3228	it by calling C<ev_async_send>, which is thread- and signal safe.
3024		3229
3025	This functionality is very similar to C<ev_signal> watchers, as signals,	3230	This functionality is very similar to C<ev_signal> watchers, as signals,
3026	too, are asynchronous in nature, and signals, too, will be compressed	3231	too, are asynchronous in nature, and signals, too, will be compressed
3027	(i.e. the number of callback invocations may be less than the number of	3232	(i.e. the number of callback invocations may be less than the number of
3028	C<ev_async_sent> calls).	3233	C<ev_async_sent> calls). In fact, you could use signal watchers as a kind
		3234	of "global async watchers" by using a watcher on an otherwise unused
		3235	signal, and C<ev_feed_signal> to signal this watcher from another thread,
		3236	even without knowing which loop owns the signal.
3029		3237
3030	Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not	3238	Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not
3031	just the default loop.	3239	just the default loop.
3032		3240
3033	=head3 Queueing	3241	=head3 Queueing
…		…
3209	Feed an event on the given fd, as if a file descriptor backend detected	3417	Feed an event on the given fd, as if a file descriptor backend detected
3210	the given events it.	3418	the given events it.
3211		3419
3212	=item ev_feed_signal_event (loop, int signum)	3420	=item ev_feed_signal_event (loop, int signum)
3213		3421
3214	Feed an event as if the given signal occurred (C<loop> must be the default	3422	Feed an event as if the given signal occurred. See also C<ev_feed_signal>,
3215	loop!).	3423	which is async-safe.
		3424
		3425	=back
		3426
		3427
		3428	=head1 COMMON OR USEFUL IDIOMS (OR BOTH)
		3429
		3430	This section explains some common idioms that are not immediately
		3431	obvious. Note that examples are sprinkled over the whole manual, and this
		3432	section only contains stuff that wouldn't fit anywhere else.
		3433
		3434	=over 4
		3435
		3436	=item Model/nested event loop invocations and exit conditions.
		3437
		3438	Often (especially in GUI toolkits) there are places where you have
		3439	I<modal> interaction, which is most easily implemented by recursively
		3440	invoking C<ev_run>.
		3441
		3442	This brings the problem of exiting - a callback might want to finish the
		3443	main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but
		3444	a modal "Are you sure?" dialog is still waiting), or just the nested one
		3445	and not the main one (e.g. user clocked "Ok" in a modal dialog), or some
		3446	other combination: In these cases, C<ev_break> will not work alone.
		3447
		3448	The solution is to maintain "break this loop" variable for each C<ev_run>
		3449	invocation, and use a loop around C<ev_run> until the condition is
		3450	triggered, using C<EVRUN_ONCE>:
		3451
		3452	// main loop
		3453	int exit_main_loop = 0;
		3454
		3455	while (!exit_main_loop)
		3456	ev_run (EV_DEFAULT_ EVRUN_ONCE);
		3457
		3458	// in a model watcher
		3459	int exit_nested_loop = 0;
		3460
		3461	while (!exit_nested_loop)
		3462	ev_run (EV_A_ EVRUN_ONCE);
		3463
		3464	To exit from any of these loops, just set the corresponding exit variable:
		3465
		3466	// exit modal loop
		3467	exit_nested_loop = 1;
		3468
		3469	// exit main program, after modal loop is finished
		3470	exit_main_loop = 1;
		3471
		3472	// exit both
		3473	exit_main_loop = exit_nested_loop = 1;
3216		3474
3217	=back	3475	=back
3218		3476
3219		3477
3220	=head1 LIBEVENT EMULATION	3478	=head1 LIBEVENT EMULATION
3221		3479
3222	Libev offers a compatibility emulation layer for libevent. It cannot	3480	Libev offers a compatibility emulation layer for libevent. It cannot
3223	emulate the internals of libevent, so here are some usage hints:	3481	emulate the internals of libevent, so here are some usage hints:
3224		3482
3225	=over 4	3483	=over 4
		3484
		3485	=item * Only the libevent-1.4.1-beta API is being emulated.
		3486
		3487	This was the newest libevent version available when libev was implemented,
		3488	and is still mostly unchanged in 2010.
3226		3489
3227	=item * Use it by including <event.h>, as usual.	3490	=item * Use it by including <event.h>, as usual.
3228		3491
3229	=item * The following members are fully supported: ev_base, ev_callback,	3492	=item * The following members are fully supported: ev_base, ev_callback,
3230	ev_arg, ev_fd, ev_res, ev_events.	3493	ev_arg, ev_fd, ev_res, ev_events.
…		…
3236	=item * Priorities are not currently supported. Initialising priorities	3499	=item * Priorities are not currently supported. Initialising priorities
3237	will fail and all watchers will have the same priority, even though there	3500	will fail and all watchers will have the same priority, even though there
3238	is an ev_pri field.	3501	is an ev_pri field.
3239		3502
3240	=item * In libevent, the last base created gets the signals, in libev, the	3503	=item * In libevent, the last base created gets the signals, in libev, the
3241	first base created (== the default loop) gets the signals.	3504	base that registered the signal gets the signals.
3242		3505
3243	=item * Other members are not supported.	3506	=item * Other members are not supported.
3244		3507
3245	=item * The libev emulation is I<not> ABI compatible to libevent, you need	3508	=item * The libev emulation is I<not> ABI compatible to libevent, you need
3246	to use the libev header file and library.	3509	to use the libev header file and library.
…		…
3265	Care has been taken to keep the overhead low. The only data member the C++	3528	Care has been taken to keep the overhead low. The only data member the C++
3266	classes add (compared to plain C-style watchers) is the event loop pointer	3529	classes add (compared to plain C-style watchers) is the event loop pointer
3267	that the watcher is associated with (or no additional members at all if	3530	that the watcher is associated with (or no additional members at all if
3268	you disable C<EV_MULTIPLICITY> when embedding libev).	3531	you disable C<EV_MULTIPLICITY> when embedding libev).
3269		3532
3270	Currently, functions, and static and non-static member functions can be	3533	Currently, functions, static and non-static member functions and classes
3271	used as callbacks. Other types should be easy to add as long as they only	3534	with C<operator ()> can be used as callbacks. Other types should be easy
3272	need one additional pointer for context. If you need support for other	3535	to add as long as they only need one additional pointer for context. If
3273	types of functors please contact the author (preferably after implementing	3536	you need support for other types of functors please contact the author
3274	it).	3537	(preferably after implementing it).
3275		3538
3276	Here is a list of things available in the C<ev> namespace:	3539	Here is a list of things available in the C<ev> namespace:
3277		3540
3278	=over 4	3541	=over 4
3279		3542
…		…
3389	Associates a different C<struct ev_loop> with this watcher. You can only	3652	Associates a different C<struct ev_loop> with this watcher. You can only
3390	do this when the watcher is inactive (and not pending either).	3653	do this when the watcher is inactive (and not pending either).
3391		3654
3392	=item w->set ([arguments])	3655	=item w->set ([arguments])
3393		3656
3394	Basically the same as C<ev_TYPE_set>, with the same arguments. Must be	3657	Basically the same as C<ev_TYPE_set>, with the same arguments. Either this
3395	called at least once. Unlike the C counterpart, an active watcher gets	3658	method or a suitable start method must be called at least once. Unlike the
3396	automatically stopped and restarted when reconfiguring it with this	3659	C counterpart, an active watcher gets automatically stopped and restarted
3397	method.	3660	when reconfiguring it with this method.
3398		3661
3399	=item w->start ()	3662	=item w->start ()
3400		3663
3401	Starts the watcher. Note that there is no C<loop> argument, as the	3664	Starts the watcher. Note that there is no C<loop> argument, as the
3402	constructor already stores the event loop.	3665	constructor already stores the event loop.
3403		3666
		3667	=item w->start ([arguments])
		3668
		3669	Instead of calling C<set> and C<start> methods separately, it is often
		3670	convenient to wrap them in one call. Uses the same type of arguments as
		3671	the configure C<set> method of the watcher.
		3672
3404	=item w->stop ()	3673	=item w->stop ()
3405		3674
3406	Stops the watcher if it is active. Again, no C<loop> argument.	3675	Stops the watcher if it is active. Again, no C<loop> argument.
3407		3676
3408	=item w->again () (C<ev::timer>, C<ev::periodic> only)	3677	=item w->again () (C<ev::timer>, C<ev::periodic> only)
…		…
3420		3689
3421	=back	3690	=back
3422		3691
3423	=back	3692	=back
3424		3693
3425	Example: Define a class with an IO and idle watcher, start one of them in	3694	Example: Define a class with two I/O and idle watchers, start the I/O
3426	the constructor.	3695	watchers in the constructor.
3427		3696
3428	class myclass	3697	class myclass
3429	{	3698	{
3430	ev::io io ; void io_cb (ev::io &w, int revents);	3699	ev::io io ; void io_cb (ev::io &w, int revents);
		3700	ev::io2 io2 ; void io2_cb (ev::io &w, int revents);
3431	ev::idle idle; void idle_cb (ev::idle &w, int revents);	3701	ev::idle idle; void idle_cb (ev::idle &w, int revents);
3432		3702
3433	myclass (int fd)	3703	myclass (int fd)
3434	{	3704	{
3435	io .set <myclass, &myclass::io_cb > (this);	3705	io .set <myclass, &myclass::io_cb > (this);
		3706	io2 .set <myclass, &myclass::io2_cb > (this);
3436	idle.set <myclass, &myclass::idle_cb> (this);	3707	idle.set <myclass, &myclass::idle_cb> (this);
3437		3708
3438	io.start (fd, ev::READ);	3709	io.set (fd, ev::WRITE); // configure the watcher
		3710	io.start (); // start it whenever convenient
		3711
		3712	io2.start (fd, ev::READ); // set + start in one call
3439	}	3713	}
3440	};	3714	};
3441		3715
3442		3716
3443	=head1 OTHER LANGUAGE BINDINGS	3717	=head1 OTHER LANGUAGE BINDINGS
…		…
3517	loop argument"). The C<EV_A> form is used when this is the sole argument,	3791	loop argument"). The C<EV_A> form is used when this is the sole argument,
3518	C<EV_A_> is used when other arguments are following. Example:	3792	C<EV_A_> is used when other arguments are following. Example:
3519		3793
3520	ev_unref (EV_A);	3794	ev_unref (EV_A);
3521	ev_timer_add (EV_A_ watcher);	3795	ev_timer_add (EV_A_ watcher);
3522	ev_loop (EV_A_ 0);	3796	ev_run (EV_A_ 0);
3523		3797
3524	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	3798	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
3525	which is often provided by the following macro.	3799	which is often provided by the following macro.
3526		3800
3527	=item C<EV_P>, C<EV_P_>	3801	=item C<EV_P>, C<EV_P_>
…		…
3567	}	3841	}
3568		3842
3569	ev_check check;	3843	ev_check check;
3570	ev_check_init (&check, check_cb);	3844	ev_check_init (&check, check_cb);
3571	ev_check_start (EV_DEFAULT_ &check);	3845	ev_check_start (EV_DEFAULT_ &check);
3572	ev_loop (EV_DEFAULT_ 0);	3846	ev_run (EV_DEFAULT_ 0);
3573		3847
3574	=head1 EMBEDDING	3848	=head1 EMBEDDING
3575		3849
3576	Libev can (and often is) directly embedded into host	3850	Libev can (and often is) directly embedded into host
3577	applications. Examples of applications that embed it include the Deliantra	3851	applications. Examples of applications that embed it include the Deliantra
…		…
3668	to a compiled library. All other symbols change the ABI, which means all	3942	to a compiled library. All other symbols change the ABI, which means all
3669	users of libev and the libev code itself must be compiled with compatible	3943	users of libev and the libev code itself must be compiled with compatible
3670	settings.	3944	settings.
3671		3945
3672	=over 4	3946	=over 4
		3947
		3948	=item EV_COMPAT3 (h)
		3949
		3950	Backwards compatibility is a major concern for libev. This is why this
		3951	release of libev comes with wrappers for the functions and symbols that
		3952	have been renamed between libev version 3 and 4.
		3953
		3954	You can disable these wrappers (to test compatibility with future
		3955	versions) by defining C<EV_COMPAT3> to C<0> when compiling your
		3956	sources. This has the additional advantage that you can drop the C<struct>
		3957	from C<struct ev_loop> declarations, as libev will provide an C<ev_loop>
		3958	typedef in that case.
		3959
		3960	In some future version, the default for C<EV_COMPAT3> will become C<0>,
		3961	and in some even more future version the compatibility code will be
		3962	removed completely.
3673		3963
3674	=item EV_STANDALONE (h)	3964	=item EV_STANDALONE (h)
3675		3965
3676	Must always be C<1> if you do not use autoconf configuration, which	3966	Must always be C<1> if you do not use autoconf configuration, which
3677	keeps libev from including F<config.h>, and it also defines dummy	3967	keeps libev from including F<config.h>, and it also defines dummy
…		…
4027	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it	4317	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
4028	will be C<0>.	4318	will be C<0>.
4029		4319
4030	=item EV_VERIFY	4320	=item EV_VERIFY
4031		4321
4032	Controls how much internal verification (see C<ev_loop_verify ()>) will	4322	Controls how much internal verification (see C<ev_verify ()>) will
4033	be done: If set to C<0>, no internal verification code will be compiled	4323	be done: If set to C<0>, no internal verification code will be compiled
4034	in. If set to C<1>, then verification code will be compiled in, but not	4324	in. If set to C<1>, then verification code will be compiled in, but not
4035	called. If set to C<2>, then the internal verification code will be	4325	called. If set to C<2>, then the internal verification code will be
4036	called once per loop, which can slow down libev. If set to C<3>, then the	4326	called once per loop, which can slow down libev. If set to C<3>, then the
4037	verification code will be called very frequently, which will slow down	4327	verification code will be called very frequently, which will slow down
…		…
4252	userdata *u = ev_userdata (EV_A);	4542	userdata *u = ev_userdata (EV_A);
4253	pthread_mutex_lock (&u->lock);	4543	pthread_mutex_lock (&u->lock);
4254	}	4544	}
4255		4545
4256	The event loop thread first acquires the mutex, and then jumps straight	4546	The event loop thread first acquires the mutex, and then jumps straight
4257	into C<ev_loop>:	4547	into C<ev_run>:
4258		4548
4259	void *	4549	void *
4260	l_run (void *thr_arg)	4550	l_run (void *thr_arg)
4261	{	4551	{
4262	struct ev_loop *loop = (struct ev_loop *)thr_arg;	4552	struct ev_loop *loop = (struct ev_loop *)thr_arg;
4263		4553
4264	l_acquire (EV_A);	4554	l_acquire (EV_A);
4265	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);	4555	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
4266	ev_loop (EV_A_ 0);	4556	ev_run (EV_A_ 0);
4267	l_release (EV_A);	4557	l_release (EV_A);
4268		4558
4269	return 0;	4559	return 0;
4270	}	4560	}
4271		4561
…		…
4323		4613
4324	=head3 COROUTINES	4614	=head3 COROUTINES
4325		4615
4326	Libev is very accommodating to coroutines ("cooperative threads"):	4616	Libev is very accommodating to coroutines ("cooperative threads"):
4327	libev fully supports nesting calls to its functions from different	4617	libev fully supports nesting calls to its functions from different
4328	coroutines (e.g. you can call C<ev_loop> on the same loop from two	4618	coroutines (e.g. you can call C<ev_run> on the same loop from two
4329	different coroutines, and switch freely between both coroutines running	4619	different coroutines, and switch freely between both coroutines running
4330	the loop, as long as you don't confuse yourself). The only exception is	4620	the loop, as long as you don't confuse yourself). The only exception is
4331	that you must not do this from C<ev_periodic> reschedule callbacks.	4621	that you must not do this from C<ev_periodic> reschedule callbacks.
4332		4622
4333	Care has been taken to ensure that libev does not keep local state inside	4623	Care has been taken to ensure that libev does not keep local state inside
4334	C<ev_loop>, and other calls do not usually allow for coroutine switches as	4624	C<ev_run>, and other calls do not usually allow for coroutine switches as
4335	they do not call any callbacks.	4625	they do not call any callbacks.
4336		4626
4337	=head2 COMPILER WARNINGS	4627	=head2 COMPILER WARNINGS
4338		4628
4339	Depending on your compiler and compiler settings, you might get no or a	4629	Depending on your compiler and compiler settings, you might get no or a
…		…
4423	=head3 C<kqueue> is buggy	4713	=head3 C<kqueue> is buggy
4424		4714
4425	The kqueue syscall is broken in all known versions - most versions support	4715	The kqueue syscall is broken in all known versions - most versions support
4426	only sockets, many support pipes.	4716	only sockets, many support pipes.
4427		4717
4428	Libev tries to work around this by not using C<kqueue> by default on	4718	Libev tries to work around this by not using C<kqueue> by default on this
4429	this rotten platform, but of course you can still ask for it when creating	4719	rotten platform, but of course you can still ask for it when creating a
4430	a loop.	4720	loop - embedding a socket-only kqueue loop into a select-based one is
		4721	probably going to work well.
4431		4722
4432	=head3 C<poll> is buggy	4723	=head3 C<poll> is buggy
4433		4724
4434	Instead of fixing C<kqueue>, Apple replaced their (working) C<poll>	4725	Instead of fixing C<kqueue>, Apple replaced their (working) C<poll>
4435	implementation by something calling C<kqueue> internally around the 10.5.6	4726	implementation by something calling C<kqueue> internally around the 10.5.6
…		…
4454		4745
4455	=head3 C<errno> reentrancy	4746	=head3 C<errno> reentrancy
4456		4747
4457	The default compile environment on Solaris is unfortunately so	4748	The default compile environment on Solaris is unfortunately so
4458	thread-unsafe that you can't even use components/libraries compiled	4749	thread-unsafe that you can't even use components/libraries compiled
4459	without C<-D_REENTRANT> (as long as they use C<errno>), which, of course,	4750	without C<-D_REENTRANT> in a threaded program, which, of course, isn't
4460	isn't defined by default.	4751	defined by default. A valid, if stupid, implementation choice.
4461		4752
4462	If you want to use libev in threaded environments you have to make sure	4753	If you want to use libev in threaded environments you have to make sure
4463	it's compiled with C<_REENTRANT> defined.	4754	it's compiled with C<_REENTRANT> defined.
4464		4755
4465	=head3 Event port backend	4756	=head3 Event port backend
4466		4757
4467	The scalable event interface for Solaris is called "event ports". Unfortunately,	4758	The scalable event interface for Solaris is called "event
4468	this mechanism is very buggy. If you run into high CPU usage, your program	4759	ports". Unfortunately, this mechanism is very buggy in all major
		4760	releases. If you run into high CPU usage, your program freezes or you get
4469	freezes or you get a large number of spurious wakeups, make sure you have	4761	a large number of spurious wakeups, make sure you have all the relevant
4470	all the relevant and latest kernel patches applied. No, I don't know which	4762	and latest kernel patches applied. No, I don't know which ones, but there
4471	ones, but there are multiple ones.	4763	are multiple ones to apply, and afterwards, event ports actually work
		4764	great.
4472		4765
4473	If you can't get it to work, you can try running the program by setting	4766	If you can't get it to work, you can try running the program by setting
4474	the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and	4767	the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and
4475	C<select> backends.	4768	C<select> backends.
4476		4769
4477	=head2 AIX POLL BUG	4770	=head2 AIX POLL BUG
4478		4771
4479	AIX unfortunately has a broken C<poll.h> header. Libev works around	4772	AIX unfortunately has a broken C<poll.h> header. Libev works around
4480	this by trying to avoid the poll backend altogether (i.e. it's not even	4773	this by trying to avoid the poll backend altogether (i.e. it's not even
4481	compiled in), which normally isn't a big problem as C<select> works fine	4774	compiled in), which normally isn't a big problem as C<select> works fine
4482	with large bitsets, and AIX is dead anyway.	4775	with large bitsets on AIX, and AIX is dead anyway.
4483		4776
4484	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS	4777	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
4485		4778
4486	=head3 General issues	4779	=head3 General issues
4487		4780
…		…
4593	structure (guaranteed by POSIX but not by ISO C for example), but it also	4886	structure (guaranteed by POSIX but not by ISO C for example), but it also
4594	assumes that the same (machine) code can be used to call any watcher	4887	assumes that the same (machine) code can be used to call any watcher
4595	callback: The watcher callbacks have different type signatures, but libev	4888	callback: The watcher callbacks have different type signatures, but libev
4596	calls them using an C<ev_watcher *> internally.	4889	calls them using an C<ev_watcher *> internally.
4597		4890
		4891	=item pointer accesses must be thread-atomic
		4892
		4893	Accessing a pointer value must be atomic, it must both be readable and
		4894	writable in one piece - this is the case on all current architectures.
		4895
4598	=item C<sig_atomic_t volatile> must be thread-atomic as well	4896	=item C<sig_atomic_t volatile> must be thread-atomic as well
4599		4897
4600	The type C<sig_atomic_t volatile> (or whatever is defined as	4898	The type C<sig_atomic_t volatile> (or whatever is defined as
4601	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different	4899	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different
4602	threads. This is not part of the specification for C<sig_atomic_t>, but is	4900	threads. This is not part of the specification for C<sig_atomic_t>, but is
…		…
4624	watchers.	4922	watchers.
4625		4923
4626	=item C<double> must hold a time value in seconds with enough accuracy	4924	=item C<double> must hold a time value in seconds with enough accuracy
4627		4925
4628	The type C<double> is used to represent timestamps. It is required to	4926	The type C<double> is used to represent timestamps. It is required to
4629	have at least 51 bits of mantissa (and 9 bits of exponent), which is good	4927	have at least 51 bits of mantissa (and 9 bits of exponent), which is
4630	enough for at least into the year 4000. This requirement is fulfilled by	4928	good enough for at least into the year 4000 with millisecond accuracy
		4929	(the design goal for libev). This requirement is overfulfilled by
4631	implementations implementing IEEE 754, which is basically all existing	4930	implementations using IEEE 754, which is basically all existing ones. With
4632	ones. With IEEE 754 doubles, you get microsecond accuracy until at least	4931	IEEE 754 doubles, you get microsecond accuracy until at least 2200.
4633	2200.
4634		4932
4635	=back	4933	=back
4636		4934
4637	If you know of other additional requirements drop me a note.	4935	If you know of other additional requirements drop me a note.
4638		4936
…		…
4708	=back	5006	=back
4709		5007
4710		5008
4711	=head1 PORTING FROM LIBEV 3.X TO 4.X	5009	=head1 PORTING FROM LIBEV 3.X TO 4.X
4712		5010
4713	The major version 4 introduced some minor incompatible changes to the API.	5011	The major version 4 introduced some incompatible changes to the API.
4714		5012
4715	At the moment, the C<ev.h> header file tries to implement superficial	5013	At the moment, the C<ev.h> header file provides compatibility definitions
4716	compatibility, so most programs should still compile. Those might be	5014	for all changes, so most programs should still compile. The compatibility
4717	removed in later versions of libev, so better update early than late.	5015	layer might be removed in later versions of libev, so better update to the
		5016	new API early than late.
4718		5017
4719	=over 4	5018	=over 4
4720		5019
4721	=item C<ev_loop_count> renamed to C<ev_iteration>	5020	=item C<EV_COMPAT3> backwards compatibility mechanism
4722		5021
4723	=item C<ev_loop_depth> renamed to C<ev_depth>	5022	The backward compatibility mechanism can be controlled by
		5023	C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING>
		5024	section.
4724		5025
4725	=item C<ev_loop_verify> renamed to C<ev_verify>	5026	=item C<ev_default_destroy> and C<ev_default_fork> have been removed
		5027
		5028	These calls can be replaced easily by their C<ev_loop_xxx> counterparts:
		5029
		5030	ev_loop_destroy (EV_DEFAULT_UC);
		5031	ev_loop_fork (EV_DEFAULT);
		5032
		5033	=item function/symbol renames
		5034
		5035	A number of functions and symbols have been renamed:
		5036
		5037	ev_loop => ev_run
		5038	EVLOOP_NONBLOCK => EVRUN_NOWAIT
		5039	EVLOOP_ONESHOT => EVRUN_ONCE
		5040
		5041	ev_unloop => ev_break
		5042	EVUNLOOP_CANCEL => EVBREAK_CANCEL
		5043	EVUNLOOP_ONE => EVBREAK_ONE
		5044	EVUNLOOP_ALL => EVBREAK_ALL
		5045
		5046	EV_TIMEOUT => EV_TIMER
		5047
		5048	ev_loop_count => ev_iteration
		5049	ev_loop_depth => ev_depth
		5050	ev_loop_verify => ev_verify
4726		5051
4727	Most functions working on C<struct ev_loop> objects don't have an	5052	Most functions working on C<struct ev_loop> objects don't have an
4728	C<ev_loop_> prefix, so it was removed. Note that C<ev_loop_fork> is	5053	C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and
		5054	associated constants have been renamed to not collide with the C<struct
		5055	ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme
		5056	as all other watcher types. Note that C<ev_loop_fork> is still called
4729	still called C<ev_loop_fork> because it would otherwise clash with the	5057	C<ev_loop_fork> because it would otherwise clash with the C<ev_fork>
4730	C<ev_fork> typedef.	5058	typedef.
4731
4732	=item C<EV_TIMEOUT> renamed to C<EV_TIMER> in C<revents>
4733
4734	This is a simple rename - all other watcher types use their name
4735	as revents flag, and now C<ev_timer> does, too.
4736
4737	Both C<EV_TIMER> and C<EV_TIMEOUT> symbols were present in 3.x versions
4738	and continue to be present for the foreseeable future, so this is mostly a
4739	documentation change.
4740		5059
4741	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>	5060	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>
4742		5061
4743	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different	5062	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different
4744	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile	5063	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile
…		…
4751		5070
4752	=over 4	5071	=over 4
4753		5072
4754	=item active	5073	=item active
4755		5074
4756	A watcher is active as long as it has been started (has been attached to	5075	A watcher is active as long as it has been started and not yet stopped.
4757	an event loop) but not yet stopped (disassociated from the event loop).	5076	See L<WATCHER STATES> for details.
4758		5077
4759	=item application	5078	=item application
4760		5079
4761	In this document, an application is whatever is using libev.	5080	In this document, an application is whatever is using libev.
		5081
		5082	=item backend
		5083
		5084	The part of the code dealing with the operating system interfaces.
4762		5085
4763	=item callback	5086	=item callback
4764		5087
4765	The address of a function that is called when some event has been	5088	The address of a function that is called when some event has been
4766	detected. Callbacks are being passed the event loop, the watcher that	5089	detected. Callbacks are being passed the event loop, the watcher that
4767	received the event, and the actual event bitset.	5090	received the event, and the actual event bitset.
4768		5091
4769	=item callback invocation	5092	=item callback/watcher invocation
4770		5093
4771	The act of calling the callback associated with a watcher.	5094	The act of calling the callback associated with a watcher.
4772		5095
4773	=item event	5096	=item event
4774		5097
…		…
4793	The model used to describe how an event loop handles and processes	5116	The model used to describe how an event loop handles and processes
4794	watchers and events.	5117	watchers and events.
4795		5118
4796	=item pending	5119	=item pending
4797		5120
4798	A watcher is pending as soon as the corresponding event has been detected,	5121	A watcher is pending as soon as the corresponding event has been
4799	and stops being pending as soon as the watcher will be invoked or its	5122	detected. See L<WATCHER STATES> for details.
4800	pending status is explicitly cleared by the application.
4801
4802	A watcher can be pending, but not active. Stopping a watcher also clears
4803	its pending status.
4804		5123
4805	=item real time	5124	=item real time
4806		5125
4807	The physical time that is observed. It is apparently strictly monotonic :)	5126	The physical time that is observed. It is apparently strictly monotonic :)
4808		5127
…		…
4815	=item watcher	5134	=item watcher
4816		5135
4817	A data structure that describes interest in certain events. Watchers need	5136	A data structure that describes interest in certain events. Watchers need
4818	to be started (attached to an event loop) before they can receive events.	5137	to be started (attached to an event loop) before they can receive events.
4819		5138
4820	=item watcher invocation
4821
4822	The act of calling the callback associated with a watcher.
4823
4824	=back	5139	=back
4825		5140
4826	=head1 AUTHOR	5141	=head1 AUTHOR
4827		5142
4828	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson.	5143	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael
		5144	Magnusson and Emanuele Giaquinta.
4829		5145

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