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Revision 1.292 by sf-exg, Mon Mar 22 09:57:01 2010 UTC vs.
Revision 1.335 by root, Mon Oct 25 10:32:05 2010 UTC

…		…
26	puts ("stdin ready");	26	puts ("stdin ready");
27	// for one-shot events, one must manually stop the watcher	27	// for one-shot events, one must manually stop the watcher
28	// with its corresponding stop function.	28	// with its corresponding stop function.
29	ev_io_stop (EV_A_ w);	29	ev_io_stop (EV_A_ w);
30		30
31	// this causes all nested ev_loop's to stop iterating	31	// this causes all nested ev_run's to stop iterating
32	ev_unloop (EV_A_ EVUNLOOP_ALL);	32	ev_break (EV_A_ EVBREAK_ALL);
33	}	33	}
34		34
35	// another callback, this time for a time-out	35	// another callback, this time for a time-out
36	static void	36	static void
37	timeout_cb (EV_P_ ev_timer *w, int revents)	37	timeout_cb (EV_P_ ev_timer *w, int revents)
38	{	38	{
39	puts ("timeout");	39	puts ("timeout");
40	// this causes the innermost ev_loop to stop iterating	40	// this causes the innermost ev_run to stop iterating
41	ev_unloop (EV_A_ EVUNLOOP_ONE);	41	ev_break (EV_A_ EVBREAK_ONE);
42	}	42	}
43		43
44	int	44	int
45	main (void)	45	main (void)
46	{	46	{
47	// use the default event loop unless you have special needs	47	// use the default event loop unless you have special needs
48	struct ev_loop *loop = ev_default_loop (0);	48	struct ev_loop *loop = EV_DEFAULT;
49		49
50	// initialise an io watcher, then start it	50	// initialise an io watcher, then start it
51	// this one will watch for stdin to become readable	51	// this one will watch for stdin to become readable
52	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);	52	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);
53	ev_io_start (loop, &stdin_watcher);	53	ev_io_start (loop, &stdin_watcher);
…		…
56	// simple non-repeating 5.5 second timeout	56	// simple non-repeating 5.5 second timeout
57	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);	57	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
58	ev_timer_start (loop, &timeout_watcher);	58	ev_timer_start (loop, &timeout_watcher);
59		59
60	// now wait for events to arrive	60	// now wait for events to arrive
61	ev_loop (loop, 0);	61	ev_run (loop, 0);
62		62
63	// unloop was called, so exit	63	// unloop was called, so exit
64	return 0;	64	return 0;
65	}	65	}
66		66
…		…
75	While this document tries to be as complete as possible in documenting	75	While this document tries to be as complete as possible in documenting
76	libev, its usage and the rationale behind its design, it is not a tutorial	76	libev, its usage and the rationale behind its design, it is not a tutorial
77	on event-based programming, nor will it introduce event-based programming	77	on event-based programming, nor will it introduce event-based programming
78	with libev.	78	with libev.
79		79
80	Familarity with event based programming techniques in general is assumed	80	Familiarity with event based programming techniques in general is assumed
81	throughout this document.	81	throughout this document.
		82
		83	=head1 WHAT TO READ WHEN IN A HURRY
		84
		85	This manual tries to be very detailed, but unfortunately, this also makes
		86	it very long. If you just want to know the basics of libev, I suggest
		87	reading L<ANATOMY OF A WATCHER>, then the L<EXAMPLE PROGRAM> above and
		88	look up the missing functions in L<GLOBAL FUNCTIONS> and the C<ev_io> and
		89	C<ev_timer> sections in L<WATCHER TYPES>.
82		90
83	=head1 ABOUT LIBEV	91	=head1 ABOUT LIBEV
84		92
85	Libev is an event loop: you register interest in certain events (such as a	93	Libev is an event loop: you register interest in certain events (such as a
86	file descriptor being readable or a timeout occurring), and it will manage	94	file descriptor being readable or a timeout occurring), and it will manage
…		…
124	this argument.	132	this argument.
125		133
126	=head2 TIME REPRESENTATION	134	=head2 TIME REPRESENTATION
127		135
128	Libev represents time as a single floating point number, representing	136	Libev represents time as a single floating point number, representing
129	the (fractional) number of seconds since the (POSIX) epoch (somewhere	137	the (fractional) number of seconds since the (POSIX) epoch (in practice
130	near the beginning of 1970, details are complicated, don't ask). This	138	somewhere near the beginning of 1970, details are complicated, don't
131	type is called C<ev_tstamp>, which is what you should use too. It usually	139	ask). This type is called C<ev_tstamp>, which is what you should use
132	aliases to the C<double> type in C. When you need to do any calculations	140	too. It usually aliases to the C<double> type in C. When you need to do
133	on it, you should treat it as some floating point value. Unlike the name	141	any calculations on it, you should treat it as some floating point value.
		142
134	component C<stamp> might indicate, it is also used for time differences	143	Unlike the name component C<stamp> might indicate, it is also used for
135	throughout libev.	144	time differences (e.g. delays) throughout libev.
136		145
137	=head1 ERROR HANDLING	146	=head1 ERROR HANDLING
138		147
139	Libev knows three classes of errors: operating system errors, usage errors	148	Libev knows three classes of errors: operating system errors, usage errors
140	and internal errors (bugs).	149	and internal errors (bugs).
…		…
164		173
165	=item ev_tstamp ev_time ()	174	=item ev_tstamp ev_time ()
166		175
167	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
168	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
169	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>.
170		180
171	=item ev_sleep (ev_tstamp interval)	181	=item ev_sleep (ev_tstamp interval)
172		182
173	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
174	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
…		…
191	as this indicates an incompatible change. Minor versions are usually	201	as this indicates an incompatible change. Minor versions are usually
192	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
193	not a problem.	203	not a problem.
194		204
195	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
196	version.	206	version (note, however, that this will not detect other ABI mismatches,
		207	such as LFS or reentrancy).
197		208
198	assert (("libev version mismatch",	209	assert (("libev version mismatch",
199	ev_version_major () == EV_VERSION_MAJOR	210	ev_version_major () == EV_VERSION_MAJOR
200	&& ev_version_minor () >= EV_VERSION_MINOR));	211	&& ev_version_minor () >= EV_VERSION_MINOR));
201		212
…		…
212	assert (("sorry, no epoll, no sex",	223	assert (("sorry, no epoll, no sex",
213	ev_supported_backends () & EVBACKEND_EPOLL));	224	ev_supported_backends () & EVBACKEND_EPOLL));
214		225
215	=item unsigned int ev_recommended_backends ()	226	=item unsigned int ev_recommended_backends ()
216		227
217	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
218	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
219	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
220	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
221	(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
222	libev will probe for if you specify no backends explicitly.	234	probe for if you specify no backends explicitly.
223		235
224	=item unsigned int ev_embeddable_backends ()	236	=item unsigned int ev_embeddable_backends ()
225		237
226	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
227	is the theoretical, all-platform, value. To find which backends	239	value is platform-specific but can include backends not available on the
228	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
229	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for	241	the current system, you would need to look at C<ev_embeddable_backends ()
230	recommended ones.	242	& ev_supported_backends ()>, likewise for recommended ones.
231		243
232	See the description of C<ev_embed> watchers for more info.	244	See the description of C<ev_embed> watchers for more info.
233		245
234	=item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT]	246	=item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT]
235		247
…		…
289	...	301	...
290	ev_set_syserr_cb (fatal_error);	302	ev_set_syserr_cb (fatal_error);
291		303
292	=back	304	=back
293		305
294	=head1 FUNCTIONS CONTROLLING THE EVENT LOOP	306	=head1 FUNCTIONS CONTROLLING EVENT LOOPS
295		307
296	An event loop is described by a C<struct ev_loop *> (the C<struct>	308	An event loop is described by a C<struct ev_loop *> (the C<struct> is
297	is I<not> optional in this case, as there is also an C<ev_loop>	309	I<not> optional in this case unless libev 3 compatibility is disabled, as
298	I<function>).	310	libev 3 had an C<ev_loop> function colliding with the struct name).
299		311
300	The library knows two types of such loops, the I<default> loop, which	312	The library knows two types of such loops, the I<default> loop, which
301	supports signals and child events, and dynamically created loops which do	313	supports child process events, and dynamically created event loops which
302	not.	314	do not.
303		315
304	=over 4	316	=over 4
305		317
306	=item struct ev_loop *ev_default_loop (unsigned int flags)	318	=item struct ev_loop *ev_default_loop (unsigned int flags)
307		319
308	This will initialise the default event loop if it hasn't been initialised	320	This returns the "default" event loop object, which is what you should
309	yet and return it. If the default loop could not be initialised, returns	321	normally use when you just need "the event loop". Event loop objects and
310	false. If it already was initialised it simply returns it (and ignores the	322	the C<flags> parameter are described in more detail in the entry for
311	flags. If that is troubling you, check C<ev_backend ()> afterwards).	323	C<ev_loop_new>.
		324
		325	If the default loop is already initialised then this function simply
		326	returns it (and ignores the flags. If that is troubling you, check
		327	C<ev_backend ()> afterwards). Otherwise it will create it with the given
		328	flags, which should almost always be C<0>, unless the caller is also the
		329	one calling C<ev_run> or otherwise qualifies as "the main program".
312		330
313	If you don't know what event loop to use, use the one returned from this	331	If you don't know what event loop to use, use the one returned from this
314	function.	332	function (or via the C<EV_DEFAULT> macro).
315		333
316	Note that this function is I<not> thread-safe, so if you want to use it	334	Note that this function is I<not> thread-safe, so if you want to use it
317	from multiple threads, you have to lock (note also that this is unlikely,	335	from multiple threads, you have to employ some kind of mutex (note also
318	as loops cannot be shared easily between threads anyway).	336	that this case is unlikely, as loops cannot be shared easily between
		337	threads anyway).
319		338
320	The default loop is the only loop that can handle C<ev_signal> and	339	The default loop is the only loop that can handle C<ev_child> watchers,
321	C<ev_child> watchers, and to do this, it always registers a handler	340	and to do this, it always registers a handler for C<SIGCHLD>. If this is
322	for C<SIGCHLD>. If this is a problem for your application you can either	341	a problem for your application you can either create a dynamic loop with
323	create a dynamic loop with C<ev_loop_new> that doesn't do that, or you	342	C<ev_loop_new> which doesn't do that, or you can simply overwrite the
324	can simply overwrite the C<SIGCHLD> signal handler I<after> calling	343	C<SIGCHLD> signal handler I<after> calling C<ev_default_init>.
325	C<ev_default_init>.	344
		345	Example: This is the most typical usage.
		346
		347	if (!ev_default_loop (0))
		348	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
		349
		350	Example: Restrict libev to the select and poll backends, and do not allow
		351	environment settings to be taken into account:
		352
		353	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
		354
		355	=item struct ev_loop *ev_loop_new (unsigned int flags)
		356
		357	This will create and initialise a new event loop object. If the loop
		358	could not be initialised, returns false.
		359
		360	Note that this function I<is> thread-safe, and one common way to use
		361	libev with threads is indeed to create one loop per thread, and using the
		362	default loop in the "main" or "initial" thread.
326		363
327	The flags argument can be used to specify special behaviour or specific	364	The flags argument can be used to specify special behaviour or specific
328	backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>).	365	backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>).
329		366
330	The following flags are supported:	367	The following flags are supported:
…		…
438	of course I<doesn't>, and epoll just loves to report events for totally	475	of course I<doesn't>, and epoll just loves to report events for totally
439	I<different> file descriptors (even already closed ones, so one cannot	476	I<different> file descriptors (even already closed ones, so one cannot
440	even remove them from the set) than registered in the set (especially	477	even remove them from the set) than registered in the set (especially
441	on SMP systems). Libev tries to counter these spurious notifications by	478	on SMP systems). Libev tries to counter these spurious notifications by
442	employing an additional generation counter and comparing that against the	479	employing an additional generation counter and comparing that against the
443	events to filter out spurious ones, recreating the set when required.	480	events to filter out spurious ones, recreating the set when required. Last
		481	not least, it also refuses to work with some file descriptors which work
		482	perfectly fine with C<select> (files, many character devices...).
444		483
445	While stopping, setting and starting an I/O watcher in the same iteration	484	While stopping, setting and starting an I/O watcher in the same iteration
446	will result in some caching, there is still a system call per such	485	will result in some caching, there is still a system call per such
447	incident (because the same I<file descriptor> could point to a different	486	incident (because the same I<file descriptor> could point to a different
448	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed	487	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed
…		…
546	If one or more of the backend flags are or'ed into the flags value,	585	If one or more of the backend flags are or'ed into the flags value,
547	then only these backends will be tried (in the reverse order as listed	586	then only these backends will be tried (in the reverse order as listed
548	here). If none are specified, all backends in C<ev_recommended_backends	587	here). If none are specified, all backends in C<ev_recommended_backends
549	()> will be tried.	588	()> will be tried.
550		589
551	Example: This is the most typical usage.
552
553	if (!ev_default_loop (0))
554	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
555
556	Example: Restrict libev to the select and poll backends, and do not allow
557	environment settings to be taken into account:
558
559	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
560
561	Example: Use whatever libev has to offer, but make sure that kqueue is
562	used if available (warning, breaks stuff, best use only with your own
563	private event loop and only if you know the OS supports your types of
564	fds):
565
566	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
567
568	=item struct ev_loop *ev_loop_new (unsigned int flags)
569
570	Similar to C<ev_default_loop>, but always creates a new event loop that is
571	always distinct from the default loop.
572
573	Note that this function I<is> thread-safe, and one common way to use
574	libev with threads is indeed to create one loop per thread, and using the
575	default loop in the "main" or "initial" thread.
576
577	Example: Try to create a event loop that uses epoll and nothing else.	590	Example: Try to create a event loop that uses epoll and nothing else.
578		591
579	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	592	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
580	if (!epoller)	593	if (!epoller)
581	fatal ("no epoll found here, maybe it hides under your chair");	594	fatal ("no epoll found here, maybe it hides under your chair");
582		595
		596	Example: Use whatever libev has to offer, but make sure that kqueue is
		597	used if available.
		598
		599	struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE);
		600
583	=item ev_default_destroy ()	601	=item ev_loop_destroy (loop)
584		602
585	Destroys the default loop (frees all memory and kernel state etc.). None	603	Destroys an event loop object (frees all memory and kernel state
586	of the active event watchers will be stopped in the normal sense, so	604	etc.). None of the active event watchers will be stopped in the normal
587	e.g. C<ev_is_active> might still return true. It is your responsibility to	605	sense, so e.g. C<ev_is_active> might still return true. It is your
588	either stop all watchers cleanly yourself I<before> calling this function,	606	responsibility to either stop all watchers cleanly yourself I<before>
589	or cope with the fact afterwards (which is usually the easiest thing, you	607	calling this function, or cope with the fact afterwards (which is usually
590	can just ignore the watchers and/or C<free ()> them for example).	608	the easiest thing, you can just ignore the watchers and/or C<free ()> them
		609	for example).
591		610
592	Note that certain global state, such as signal state (and installed signal	611	Note that certain global state, such as signal state (and installed signal
593	handlers), will not be freed by this function, and related watchers (such	612	handlers), will not be freed by this function, and related watchers (such
594	as signal and child watchers) would need to be stopped manually.	613	as signal and child watchers) would need to be stopped manually.
595		614
596	In general it is not advisable to call this function except in the	615	This function is normally used on loop objects allocated by
597	rare occasion where you really need to free e.g. the signal handling	616	C<ev_loop_new>, but it can also be used on the default loop returned by
		617	C<ev_default_loop>, in which case it is not thread-safe.
		618
		619	Note that it is not advisable to call this function on the default loop
		620	except in the rare occasion where you really need to free it's resources.
598	pipe fds. If you need dynamically allocated loops it is better to use	621	If you need dynamically allocated loops it is better to use C<ev_loop_new>
599	C<ev_loop_new> and C<ev_loop_destroy>.	622	and C<ev_loop_destroy>.
600		623
601	=item ev_loop_destroy (loop)	624	=item ev_loop_fork (loop)
602		625
603	Like C<ev_default_destroy>, but destroys an event loop created by an
604	earlier call to C<ev_loop_new>.
605
606	=item ev_default_fork ()
607
608	This function sets a flag that causes subsequent C<ev_loop> iterations	626	This function sets a flag that causes subsequent C<ev_run> iterations to
609	to reinitialise the kernel state for backends that have one. Despite the	627	reinitialise the kernel state for backends that have one. Despite the
610	name, you can call it anytime, but it makes most sense after forking, in	628	name, you can call it anytime, but it makes most sense after forking, in
611	the child process (or both child and parent, but that again makes little	629	the child process. You I<must> call it (or use C<EVFLAG_FORKCHECK>) in the
612	sense). You I<must> call it in the child before using any of the libev	630	child before resuming or calling C<ev_run>.
613	functions, and it will only take effect at the next C<ev_loop> iteration.
614		631
615	Again, you I<have> to call it on I<any> loop that you want to re-use after	632	Again, you I<have> to call it on I<any> loop that you want to re-use after
616	a fork, I<even if you do not plan to use the loop in the parent>. This is	633	a fork, I<even if you do not plan to use the loop in the parent>. This is
617	because some kernel interfaces *cough* I<kqueue> *cough* do funny things	634	because some kernel interfaces *cough* I<kqueue> *cough* do funny things
618	during fork.	635	during fork.
619		636
620	On the other hand, you only need to call this function in the child	637	On the other hand, you only need to call this function in the child
621	process if and only if you want to use the event loop in the child. If you	638	process if and only if you want to use the event loop in the child. If
622	just fork+exec or create a new loop in the child, you don't have to call	639	you just fork+exec or create a new loop in the child, you don't have to
623	it at all.	640	call it at all (in fact, C<epoll> is so badly broken that it makes a
		641	difference, but libev will usually detect this case on its own and do a
		642	costly reset of the backend).
624		643
625	The function itself is quite fast and it's usually not a problem to call	644	The function itself is quite fast and it's usually not a problem to call
626	it just in case after a fork. To make this easy, the function will fit in	645	it just in case after a fork.
627	quite nicely into a call to C<pthread_atfork>:
628		646
		647	Example: Automate calling C<ev_loop_fork> on the default loop when
		648	using pthreads.
		649
		650	static void
		651	post_fork_child (void)
		652	{
		653	ev_loop_fork (EV_DEFAULT);
		654	}
		655
		656	...
629	pthread_atfork (0, 0, ev_default_fork);	657	pthread_atfork (0, 0, post_fork_child);
630
631	=item ev_loop_fork (loop)
632
633	Like C<ev_default_fork>, but acts on an event loop created by
634	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
635	after fork that you want to re-use in the child, and how you keep track of
636	them is entirely your own problem.
637		658
638	=item int ev_is_default_loop (loop)	659	=item int ev_is_default_loop (loop)
639		660
640	Returns true when the given loop is, in fact, the default loop, and false	661	Returns true when the given loop is, in fact, the default loop, and false
641	otherwise.	662	otherwise.
642		663
643	=item unsigned int ev_iteration (loop)	664	=item unsigned int ev_iteration (loop)
644		665
645	Returns the current iteration count for the loop, which is identical to	666	Returns the current iteration count for the event loop, which is identical
646	the number of times libev did poll for new events. It starts at C<0> and	667	to the number of times libev did poll for new events. It starts at C<0>
647	happily wraps around with enough iterations.	668	and happily wraps around with enough iterations.
648		669
649	This value can sometimes be useful as a generation counter of sorts (it	670	This value can sometimes be useful as a generation counter of sorts (it
650	"ticks" the number of loop iterations), as it roughly corresponds with	671	"ticks" the number of loop iterations), as it roughly corresponds with
651	C<ev_prepare> and C<ev_check> calls - and is incremented between the	672	C<ev_prepare> and C<ev_check> calls - and is incremented between the
652	prepare and check phases.	673	prepare and check phases.
653		674
654	=item unsigned int ev_depth (loop)	675	=item unsigned int ev_depth (loop)
655		676
656	Returns the number of times C<ev_loop> was entered minus the number of	677	Returns the number of times C<ev_run> was entered minus the number of
657	times C<ev_loop> was exited, in other words, the recursion depth.	678	times C<ev_run> was exited, in other words, the recursion depth.
658		679
659	Outside C<ev_loop>, this number is zero. In a callback, this number is	680	Outside C<ev_run>, this number is zero. In a callback, this number is
660	C<1>, unless C<ev_loop> was invoked recursively (or from another thread),	681	C<1>, unless C<ev_run> was invoked recursively (or from another thread),
661	in which case it is higher.	682	in which case it is higher.
662		683
663	Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread	684	Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread
664	etc.), doesn't count as "exit" - consider this as a hint to avoid such	685	etc.), doesn't count as "exit" - consider this as a hint to avoid such
665	ungentleman behaviour unless it's really convenient.	686	ungentleman-like behaviour unless it's really convenient.
666		687
667	=item unsigned int ev_backend (loop)	688	=item unsigned int ev_backend (loop)
668		689
669	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	690	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
670	use.	691	use.
…		…
679		700
680	=item ev_now_update (loop)	701	=item ev_now_update (loop)
681		702
682	Establishes the current time by querying the kernel, updating the time	703	Establishes the current time by querying the kernel, updating the time
683	returned by C<ev_now ()> in the progress. This is a costly operation and	704	returned by C<ev_now ()> in the progress. This is a costly operation and
684	is usually done automatically within C<ev_loop ()>.	705	is usually done automatically within C<ev_run ()>.
685		706
686	This function is rarely useful, but when some event callback runs for a	707	This function is rarely useful, but when some event callback runs for a
687	very long time without entering the event loop, updating libev's idea of	708	very long time without entering the event loop, updating libev's idea of
688	the current time is a good idea.	709	the current time is a good idea.
689		710
…		…
691		712
692	=item ev_suspend (loop)	713	=item ev_suspend (loop)
693		714
694	=item ev_resume (loop)	715	=item ev_resume (loop)
695		716
696	These two functions suspend and resume a loop, for use when the loop is	717	These two functions suspend and resume an event loop, for use when the
697	not used for a while and timeouts should not be processed.	718	loop is not used for a while and timeouts should not be processed.
698		719
699	A typical use case would be an interactive program such as a game: When	720	A typical use case would be an interactive program such as a game: When
700	the user presses C<^Z> to suspend the game and resumes it an hour later it	721	the user presses C<^Z> to suspend the game and resumes it an hour later it
701	would be best to handle timeouts as if no time had actually passed while	722	would be best to handle timeouts as if no time had actually passed while
702	the program was suspended. This can be achieved by calling C<ev_suspend>	723	the program was suspended. This can be achieved by calling C<ev_suspend>
…		…
704	C<ev_resume> directly afterwards to resume timer processing.	725	C<ev_resume> directly afterwards to resume timer processing.
705		726
706	Effectively, all C<ev_timer> watchers will be delayed by the time spend	727	Effectively, all C<ev_timer> watchers will be delayed by the time spend
707	between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers	728	between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers
708	will be rescheduled (that is, they will lose any events that would have	729	will be rescheduled (that is, they will lose any events that would have
709	occured while suspended).	730	occurred while suspended).
710		731
711	After calling C<ev_suspend> you B<must not> call I<any> function on the	732	After calling C<ev_suspend> you B<must not> call I<any> function on the
712	given loop other than C<ev_resume>, and you B<must not> call C<ev_resume>	733	given loop other than C<ev_resume>, and you B<must not> call C<ev_resume>
713	without a previous call to C<ev_suspend>.	734	without a previous call to C<ev_suspend>.
714		735
715	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the	736	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the
716	event loop time (see C<ev_now_update>).	737	event loop time (see C<ev_now_update>).
717		738
718	=item ev_loop (loop, int flags)	739	=item ev_run (loop, int flags)
719		740
720	Finally, this is it, the event handler. This function usually is called	741	Finally, this is it, the event handler. This function usually is called
721	after you have initialised all your watchers and you want to start	742	after you have initialised all your watchers and you want to start
722	handling events.	743	handling events. It will ask the operating system for any new events, call
		744	the watcher callbacks, an then repeat the whole process indefinitely: This
		745	is why event loops are called I<loops>.
723		746
724	If the flags argument is specified as C<0>, it will not return until	747	If the flags argument is specified as C<0>, it will keep handling events
725	either no event watchers are active anymore or C<ev_unloop> was called.	748	until either no event watchers are active anymore or C<ev_break> was
		749	called.
726		750
727	Please note that an explicit C<ev_unloop> is usually better than	751	Please note that an explicit C<ev_break> is usually better than
728	relying on all watchers to be stopped when deciding when a program has	752	relying on all watchers to be stopped when deciding when a program has
729	finished (especially in interactive programs), but having a program	753	finished (especially in interactive programs), but having a program
730	that automatically loops as long as it has to and no longer by virtue	754	that automatically loops as long as it has to and no longer by virtue
731	of relying on its watchers stopping correctly, that is truly a thing of	755	of relying on its watchers stopping correctly, that is truly a thing of
732	beauty.	756	beauty.
733		757
734	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle	758	A flags value of C<EVRUN_NOWAIT> will look for new events, will handle
735	those events and any already outstanding ones, but will not block your	759	those events and any already outstanding ones, but will not wait and
736	process in case there are no events and will return after one iteration of	760	block your process in case there are no events and will return after one
737	the loop.	761	iteration of the loop. This is sometimes useful to poll and handle new
		762	events while doing lengthy calculations, to keep the program responsive.
738		763
739	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if	764	A flags value of C<EVRUN_ONCE> will look for new events (waiting if
740	necessary) and will handle those and any already outstanding ones. It	765	necessary) and will handle those and any already outstanding ones. It
741	will block your process until at least one new event arrives (which could	766	will block your process until at least one new event arrives (which could
742	be an event internal to libev itself, so there is no guarantee that a	767	be an event internal to libev itself, so there is no guarantee that a
743	user-registered callback will be called), and will return after one	768	user-registered callback will be called), and will return after one
744	iteration of the loop.	769	iteration of the loop.
745		770
746	This is useful if you are waiting for some external event in conjunction	771	This is useful if you are waiting for some external event in conjunction
747	with something not expressible using other libev watchers (i.e. "roll your	772	with something not expressible using other libev watchers (i.e. "roll your
748	own C<ev_loop>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is	773	own C<ev_run>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is
749	usually a better approach for this kind of thing.	774	usually a better approach for this kind of thing.
750		775
751	Here are the gory details of what C<ev_loop> does:	776	Here are the gory details of what C<ev_run> does:
752		777
		778	- Increment loop depth.
		779	- Reset the ev_break status.
753	- Before the first iteration, call any pending watchers.	780	- Before the first iteration, call any pending watchers.
		781	LOOP:
754	* If EVFLAG_FORKCHECK was used, check for a fork.	782	- If EVFLAG_FORKCHECK was used, check for a fork.
755	- If a fork was detected (by any means), queue and call all fork watchers.	783	- If a fork was detected (by any means), queue and call all fork watchers.
756	- Queue and call all prepare watchers.	784	- Queue and call all prepare watchers.
		785	- If ev_break was called, goto FINISH.
757	- If we have been forked, detach and recreate the kernel state	786	- If we have been forked, detach and recreate the kernel state
758	as to not disturb the other process.	787	as to not disturb the other process.
759	- Update the kernel state with all outstanding changes.	788	- Update the kernel state with all outstanding changes.
760	- Update the "event loop time" (ev_now ()).	789	- Update the "event loop time" (ev_now ()).
761	- Calculate for how long to sleep or block, if at all	790	- Calculate for how long to sleep or block, if at all
762	(active idle watchers, EVLOOP_NONBLOCK or not having	791	(active idle watchers, EVRUN_NOWAIT or not having
763	any active watchers at all will result in not sleeping).	792	any active watchers at all will result in not sleeping).
764	- Sleep if the I/O and timer collect interval say so.	793	- Sleep if the I/O and timer collect interval say so.
		794	- Increment loop iteration counter.
765	- Block the process, waiting for any events.	795	- Block the process, waiting for any events.
766	- Queue all outstanding I/O (fd) events.	796	- Queue all outstanding I/O (fd) events.
767	- Update the "event loop time" (ev_now ()), and do time jump adjustments.	797	- Update the "event loop time" (ev_now ()), and do time jump adjustments.
768	- Queue all expired timers.	798	- Queue all expired timers.
769	- Queue all expired periodics.	799	- Queue all expired periodics.
770	- Unless any events are pending now, queue all idle watchers.	800	- Queue all idle watchers with priority higher than that of pending events.
771	- Queue all check watchers.	801	- Queue all check watchers.
772	- Call all queued watchers in reverse order (i.e. check watchers first).	802	- Call all queued watchers in reverse order (i.e. check watchers first).
773	Signals and child watchers are implemented as I/O watchers, and will	803	Signals and child watchers are implemented as I/O watchers, and will
774	be handled here by queueing them when their watcher gets executed.	804	be handled here by queueing them when their watcher gets executed.
775	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	805	- If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT
776	were used, or there are no active watchers, return, otherwise	806	were used, or there are no active watchers, goto FINISH, otherwise
777	continue with step *.	807	continue with step LOOP.
		808	FINISH:
		809	- Reset the ev_break status iff it was EVBREAK_ONE.
		810	- Decrement the loop depth.
		811	- Return.
778		812
779	Example: Queue some jobs and then loop until no events are outstanding	813	Example: Queue some jobs and then loop until no events are outstanding
780	anymore.	814	anymore.
781		815
782	... queue jobs here, make sure they register event watchers as long	816	... queue jobs here, make sure they register event watchers as long
783	... as they still have work to do (even an idle watcher will do..)	817	... as they still have work to do (even an idle watcher will do..)
784	ev_loop (my_loop, 0);	818	ev_run (my_loop, 0);
785	... jobs done or somebody called unloop. yeah!	819	... jobs done or somebody called unloop. yeah!
786		820
787	=item ev_unloop (loop, how)	821	=item ev_break (loop, how)
788		822
789	Can be used to make a call to C<ev_loop> return early (but only after it	823	Can be used to make a call to C<ev_run> return early (but only after it
790	has processed all outstanding events). The C<how> argument must be either	824	has processed all outstanding events). The C<how> argument must be either
791	C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or	825	C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or
792	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.	826	C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return.
793		827
794	This "unloop state" will be cleared when entering C<ev_loop> again.	828	This "unloop state" will be cleared when entering C<ev_run> again.
795		829
796	It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls.	830	It is safe to call C<ev_break> from outside any C<ev_run> calls. ##TODO##
797		831
798	=item ev_ref (loop)	832	=item ev_ref (loop)
799		833
800	=item ev_unref (loop)	834	=item ev_unref (loop)
801		835
802	Ref/unref can be used to add or remove a reference count on the event	836	Ref/unref can be used to add or remove a reference count on the event
803	loop: Every watcher keeps one reference, and as long as the reference	837	loop: Every watcher keeps one reference, and as long as the reference
804	count is nonzero, C<ev_loop> will not return on its own.	838	count is nonzero, C<ev_run> will not return on its own.
805		839
806	This is useful when you have a watcher that you never intend to	840	This is useful when you have a watcher that you never intend to
807	unregister, but that nevertheless should not keep C<ev_loop> from	841	unregister, but that nevertheless should not keep C<ev_run> from
808	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>	842	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>
809	before stopping it.	843	before stopping it.
810		844
811	As an example, libev itself uses this for its internal signal pipe: It	845	As an example, libev itself uses this for its internal signal pipe: It
812	is not visible to the libev user and should not keep C<ev_loop> from	846	is not visible to the libev user and should not keep C<ev_run> from
813	exiting if no event watchers registered by it are active. It is also an	847	exiting if no event watchers registered by it are active. It is also an
814	excellent way to do this for generic recurring timers or from within	848	excellent way to do this for generic recurring timers or from within
815	third-party libraries. Just remember to I<unref after start> and I<ref	849	third-party libraries. Just remember to I<unref after start> and I<ref
816	before stop> (but only if the watcher wasn't active before, or was active	850	before stop> (but only if the watcher wasn't active before, or was active
817	before, respectively. Note also that libev might stop watchers itself	851	before, respectively. Note also that libev might stop watchers itself
818	(e.g. non-repeating timers) in which case you have to C<ev_ref>	852	(e.g. non-repeating timers) in which case you have to C<ev_ref>
819	in the callback).	853	in the callback).
820		854
821	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	855	Example: Create a signal watcher, but keep it from keeping C<ev_run>
822	running when nothing else is active.	856	running when nothing else is active.
823		857
824	ev_signal exitsig;	858	ev_signal exitsig;
825	ev_signal_init (&exitsig, sig_cb, SIGINT);	859	ev_signal_init (&exitsig, sig_cb, SIGINT);
826	ev_signal_start (loop, &exitsig);	860	ev_signal_start (loop, &exitsig);
…		…
871	usually doesn't make much sense to set it to a lower value than C<0.01>,	905	usually doesn't make much sense to set it to a lower value than C<0.01>,
872	as this approaches the timing granularity of most systems. Note that if	906	as this approaches the timing granularity of most systems. Note that if
873	you do transactions with the outside world and you can't increase the	907	you do transactions with the outside world and you can't increase the
874	parallelity, then this setting will limit your transaction rate (if you	908	parallelity, then this setting will limit your transaction rate (if you
875	need to poll once per transaction and the I/O collect interval is 0.01,	909	need to poll once per transaction and the I/O collect interval is 0.01,
876	then you can't do more than 100 transations per second).	910	then you can't do more than 100 transactions per second).
877		911
878	Setting the I<timeout collect interval> can improve the opportunity for	912	Setting the I<timeout collect interval> can improve the opportunity for
879	saving power, as the program will "bundle" timer callback invocations that	913	saving power, as the program will "bundle" timer callback invocations that
880	are "near" in time together, by delaying some, thus reducing the number of	914	are "near" in time together, by delaying some, thus reducing the number of
881	times the process sleeps and wakes up again. Another useful technique to	915	times the process sleeps and wakes up again. Another useful technique to
…		…
889	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);	923	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);
890		924
891	=item ev_invoke_pending (loop)	925	=item ev_invoke_pending (loop)
892		926
893	This call will simply invoke all pending watchers while resetting their	927	This call will simply invoke all pending watchers while resetting their
894	pending state. Normally, C<ev_loop> does this automatically when required,	928	pending state. Normally, C<ev_run> does this automatically when required,
895	but when overriding the invoke callback this call comes handy.	929	but when overriding the invoke callback this call comes handy. This
		930	function can be invoked from a watcher - this can be useful for example
		931	when you want to do some lengthy calculation and want to pass further
		932	event handling to another thread (you still have to make sure only one
		933	thread executes within C<ev_invoke_pending> or C<ev_run> of course).
896		934
897	=item int ev_pending_count (loop)	935	=item int ev_pending_count (loop)
898		936
899	Returns the number of pending watchers - zero indicates that no watchers	937	Returns the number of pending watchers - zero indicates that no watchers
900	are pending.	938	are pending.
901		939
902	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))	940	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))
903		941
904	This overrides the invoke pending functionality of the loop: Instead of	942	This overrides the invoke pending functionality of the loop: Instead of
905	invoking all pending watchers when there are any, C<ev_loop> will call	943	invoking all pending watchers when there are any, C<ev_run> will call
906	this callback instead. This is useful, for example, when you want to	944	this callback instead. This is useful, for example, when you want to
907	invoke the actual watchers inside another context (another thread etc.).	945	invoke the actual watchers inside another context (another thread etc.).
908		946
909	If you want to reset the callback, use C<ev_invoke_pending> as new	947	If you want to reset the callback, use C<ev_invoke_pending> as new
910	callback.	948	callback.
…		…
913		951
914	Sometimes you want to share the same loop between multiple threads. This	952	Sometimes you want to share the same loop between multiple threads. This
915	can be done relatively simply by putting mutex_lock/unlock calls around	953	can be done relatively simply by putting mutex_lock/unlock calls around
916	each call to a libev function.	954	each call to a libev function.
917		955
918	However, C<ev_loop> can run an indefinite time, so it is not feasible to	956	However, C<ev_run> can run an indefinite time, so it is not feasible
919	wait for it to return. One way around this is to wake up the loop via	957	to wait for it to return. One way around this is to wake up the event
920	C<ev_unloop> and C<av_async_send>, another way is to set these I<release>	958	loop via C<ev_break> and C<av_async_send>, another way is to set these
921	and I<acquire> callbacks on the loop.	959	I<release> and I<acquire> callbacks on the loop.
922		960
923	When set, then C<release> will be called just before the thread is	961	When set, then C<release> will be called just before the thread is
924	suspended waiting for new events, and C<acquire> is called just	962	suspended waiting for new events, and C<acquire> is called just
925	afterwards.	963	afterwards.
926		964
…		…
929		967
930	While event loop modifications are allowed between invocations of	968	While event loop modifications are allowed between invocations of
931	C<release> and C<acquire> (that's their only purpose after all), no	969	C<release> and C<acquire> (that's their only purpose after all), no
932	modifications done will affect the event loop, i.e. adding watchers will	970	modifications done will affect the event loop, i.e. adding watchers will
933	have no effect on the set of file descriptors being watched, or the time	971	have no effect on the set of file descriptors being watched, or the time
934	waited. Use an C<ev_async> watcher to wake up C<ev_loop> when you want it	972	waited. Use an C<ev_async> watcher to wake up C<ev_run> when you want it
935	to take note of any changes you made.	973	to take note of any changes you made.
936		974
937	In theory, threads executing C<ev_loop> will be async-cancel safe between	975	In theory, threads executing C<ev_run> will be async-cancel safe between
938	invocations of C<release> and C<acquire>.	976	invocations of C<release> and C<acquire>.
939		977
940	See also the locking example in the C<THREADS> section later in this	978	See also the locking example in the C<THREADS> section later in this
941	document.	979	document.
942		980
…		…
951	These two functions can be used to associate arbitrary data with a loop,	989	These two functions can be used to associate arbitrary data with a loop,
952	and are intended solely for the C<invoke_pending_cb>, C<release> and	990	and are intended solely for the C<invoke_pending_cb>, C<release> and
953	C<acquire> callbacks described above, but of course can be (ab-)used for	991	C<acquire> callbacks described above, but of course can be (ab-)used for
954	any other purpose as well.	992	any other purpose as well.
955		993
956	=item ev_loop_verify (loop)	994	=item ev_verify (loop)
957		995
958	This function only does something when C<EV_VERIFY> support has been	996	This function only does something when C<EV_VERIFY> support has been
959	compiled in, which is the default for non-minimal builds. It tries to go	997	compiled in, which is the default for non-minimal builds. It tries to go
960	through all internal structures and checks them for validity. If anything	998	through all internal structures and checks them for validity. If anything
961	is found to be inconsistent, it will print an error message to standard	999	is found to be inconsistent, it will print an error message to standard
…		…
972		1010
973	In the following description, uppercase C<TYPE> in names stands for the	1011	In the following description, uppercase C<TYPE> in names stands for the
974	watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer	1012	watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer
975	watchers and C<ev_io_start> for I/O watchers.	1013	watchers and C<ev_io_start> for I/O watchers.
976		1014
977	A watcher is a structure that you create and register to record your	1015	A watcher is an opaque structure that you allocate and register to record
978	interest in some event. For instance, if you want to wait for STDIN to	1016	your interest in some event. To make a concrete example, imagine you want
979	become readable, you would create an C<ev_io> watcher for that:	1017	to wait for STDIN to become readable, you would create an C<ev_io> watcher
		1018	for that:
980		1019
981	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)	1020	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)
982	{	1021	{
983	ev_io_stop (w);	1022	ev_io_stop (w);
984	ev_unloop (loop, EVUNLOOP_ALL);	1023	ev_break (loop, EVBREAK_ALL);
985	}	1024	}
986		1025
987	struct ev_loop *loop = ev_default_loop (0);	1026	struct ev_loop *loop = ev_default_loop (0);
988		1027
989	ev_io stdin_watcher;	1028	ev_io stdin_watcher;
990		1029
991	ev_init (&stdin_watcher, my_cb);	1030	ev_init (&stdin_watcher, my_cb);
992	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	1031	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
993	ev_io_start (loop, &stdin_watcher);	1032	ev_io_start (loop, &stdin_watcher);
994		1033
995	ev_loop (loop, 0);	1034	ev_run (loop, 0);
996		1035
997	As you can see, you are responsible for allocating the memory for your	1036	As you can see, you are responsible for allocating the memory for your
998	watcher structures (and it is I<usually> a bad idea to do this on the	1037	watcher structures (and it is I<usually> a bad idea to do this on the
999	stack).	1038	stack).
1000		1039
1001	Each watcher has an associated watcher structure (called C<struct ev_TYPE>	1040	Each watcher has an associated watcher structure (called C<struct ev_TYPE>
1002	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).	1041	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).
1003		1042
1004	Each watcher structure must be initialised by a call to C<ev_init	1043	Each watcher structure must be initialised by a call to C<ev_init (watcher
1005	(watcher *, callback)>, which expects a callback to be provided. This	1044	*, callback)>, which expects a callback to be provided. This callback is
1006	callback gets invoked each time the event occurs (or, in the case of I/O	1045	invoked each time the event occurs (or, in the case of I/O watchers, each
1007	watchers, each time the event loop detects that the file descriptor given	1046	time the event loop detects that the file descriptor given is readable
1008	is readable and/or writable).	1047	and/or writable).
1009		1048
1010	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>	1049	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>
1011	macro to configure it, with arguments specific to the watcher type. There	1050	macro to configure it, with arguments specific to the watcher type. There
1012	is also a macro to combine initialisation and setting in one call: C<<	1051	is also a macro to combine initialisation and setting in one call: C<<
1013	ev_TYPE_init (watcher *, callback, ...) >>.	1052	ev_TYPE_init (watcher *, callback, ...) >>.
…		…
1064		1103
1065	=item C<EV_PREPARE>	1104	=item C<EV_PREPARE>
1066		1105
1067	=item C<EV_CHECK>	1106	=item C<EV_CHECK>
1068		1107
1069	All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts	1108	All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts
1070	to gather new events, and all C<ev_check> watchers are invoked just after	1109	to gather new events, and all C<ev_check> watchers are invoked just after
1071	C<ev_loop> has gathered them, but before it invokes any callbacks for any	1110	C<ev_run> has gathered them, but before it invokes any callbacks for any
1072	received events. Callbacks of both watcher types can start and stop as	1111	received events. Callbacks of both watcher types can start and stop as
1073	many watchers as they want, and all of them will be taken into account	1112	many watchers as they want, and all of them will be taken into account
1074	(for example, a C<ev_prepare> watcher might start an idle watcher to keep	1113	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
1075	C<ev_loop> from blocking).	1114	C<ev_run> from blocking).
1076		1115
1077	=item C<EV_EMBED>	1116	=item C<EV_EMBED>
1078		1117
1079	The embedded event loop specified in the C<ev_embed> watcher needs attention.	1118	The embedded event loop specified in the C<ev_embed> watcher needs attention.
1080		1119
1081	=item C<EV_FORK>	1120	=item C<EV_FORK>
1082		1121
1083	The event loop has been resumed in the child process after fork (see	1122	The event loop has been resumed in the child process after fork (see
1084	C<ev_fork>).	1123	C<ev_fork>).
		1124
		1125	=item C<EV_CLEANUP>
		1126
		1127	The event loop is about to be destroyed (see C<ev_cleanup>).
1085		1128
1086	=item C<EV_ASYNC>	1129	=item C<EV_ASYNC>
1087		1130
1088	The given async watcher has been asynchronously notified (see C<ev_async>).	1131	The given async watcher has been asynchronously notified (see C<ev_async>).
1089		1132
…		…
1261		1304
1262	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related	1305	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related
1263	functions that do not need a watcher.	1306	functions that do not need a watcher.
1264		1307
1265	=back	1308	=back
1266
1267		1309
1268	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	1310	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
1269		1311
1270	Each watcher has, by default, a member C<void *data> that you can change	1312	Each watcher has, by default, a member C<void *data> that you can change
1271	and read at any time: libev will completely ignore it. This can be used	1313	and read at any time: libev will completely ignore it. This can be used
…		…
1327	t2_cb (EV_P_ ev_timer *w, int revents)	1369	t2_cb (EV_P_ ev_timer *w, int revents)
1328	{	1370	{
1329	struct my_biggy big = (struct my_biggy *)	1371	struct my_biggy big = (struct my_biggy *)
1330	(((char *)w) - offsetof (struct my_biggy, t2));	1372	(((char *)w) - offsetof (struct my_biggy, t2));
1331	}	1373	}
		1374
		1375	=head2 WATCHER STATES
		1376
		1377	There are various watcher states mentioned throughout this manual -
		1378	active, pending and so on. In this section these states and the rules to
		1379	transition between them will be described in more detail - and while these
		1380	rules might look complicated, they usually do "the right thing".
		1381
		1382	=over 4
		1383
		1384	=item initialiased
		1385
		1386	Before a watcher can be registered with the event looop it has to be
		1387	initialised. This can be done with a call to C<ev_TYPE_init>, or calls to
		1388	C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function.
		1389
		1390	In this state it is simply some block of memory that is suitable for use
		1391	in an event loop. It can be moved around, freed, reused etc. at will.
		1392
		1393	=item started/running/active
		1394
		1395	Once a watcher has been started with a call to C<ev_TYPE_start> it becomes
		1396	property of the event loop, and is actively waiting for events. While in
		1397	this state it cannot be accessed (except in a few documented ways), moved,
		1398	freed or anything else - the only legal thing is to keep a pointer to it,
		1399	and call libev functions on it that are documented to work on active watchers.
		1400
		1401	=item pending
		1402
		1403	If a watcher is active and libev determines that an event it is interested
		1404	in has occurred (such as a timer expiring), it will become pending. It will
		1405	stay in this pending state until either it is stopped or its callback is
		1406	about to be invoked, so it is not normally pending inside the watcher
		1407	callback.
		1408
		1409	The watcher might or might not be active while it is pending (for example,
		1410	an expired non-repeating timer can be pending but no longer active). If it
		1411	is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>),
		1412	but it is still property of the event loop at this time, so cannot be
		1413	moved, freed or reused. And if it is active the rules described in the
		1414	previous item still apply.
		1415
		1416	It is also possible to feed an event on a watcher that is not active (e.g.
		1417	via C<ev_feed_event>), in which case it becomes pending without being
		1418	active.
		1419
		1420	=item stopped
		1421
		1422	A watcher can be stopped implicitly by libev (in which case it might still
		1423	be pending), or explicitly by calling its C<ev_TYPE_stop> function. The
		1424	latter will clear any pending state the watcher might be in, regardless
		1425	of whether it was active or not, so stopping a watcher explicitly before
		1426	freeing it is often a good idea.
		1427
		1428	While stopped (and not pending) the watcher is essentially in the
		1429	initialised state, that is it can be reused, moved, modified in any way
		1430	you wish.
		1431
		1432	=back
1332		1433
1333	=head2 WATCHER PRIORITY MODELS	1434	=head2 WATCHER PRIORITY MODELS
1334		1435
1335	Many event loops support I<watcher priorities>, which are usually small	1436	Many event loops support I<watcher priorities>, which are usually small
1336	integers that influence the ordering of event callback invocation	1437	integers that influence the ordering of event callback invocation
…		…
1379		1480
1380	For example, to emulate how many other event libraries handle priorities,	1481	For example, to emulate how many other event libraries handle priorities,
1381	you can associate an C<ev_idle> watcher to each such watcher, and in	1482	you can associate an C<ev_idle> watcher to each such watcher, and in
1382	the normal watcher callback, you just start the idle watcher. The real	1483	the normal watcher callback, you just start the idle watcher. The real
1383	processing is done in the idle watcher callback. This causes libev to	1484	processing is done in the idle watcher callback. This causes libev to
1384	continously poll and process kernel event data for the watcher, but when	1485	continuously poll and process kernel event data for the watcher, but when
1385	the lock-out case is known to be rare (which in turn is rare :), this is	1486	the lock-out case is known to be rare (which in turn is rare :), this is
1386	workable.	1487	workable.
1387		1488
1388	Usually, however, the lock-out model implemented that way will perform	1489	Usually, however, the lock-out model implemented that way will perform
1389	miserably under the type of load it was designed to handle. In that case,	1490	miserably under the type of load it was designed to handle. In that case,
…		…
1403	{	1504	{
1404	// stop the I/O watcher, we received the event, but	1505	// stop the I/O watcher, we received the event, but
1405	// are not yet ready to handle it.	1506	// are not yet ready to handle it.
1406	ev_io_stop (EV_A_ w);	1507	ev_io_stop (EV_A_ w);
1407		1508
1408	// start the idle watcher to ahndle the actual event.	1509	// start the idle watcher to handle the actual event.
1409	// it will not be executed as long as other watchers	1510	// it will not be executed as long as other watchers
1410	// with the default priority are receiving events.	1511	// with the default priority are receiving events.
1411	ev_idle_start (EV_A_ &idle);	1512	ev_idle_start (EV_A_ &idle);
1412	}	1513	}
1413		1514
…		…
1467		1568
1468	If you cannot use non-blocking mode, then force the use of a	1569	If you cannot use non-blocking mode, then force the use of a
1469	known-to-be-good backend (at the time of this writing, this includes only	1570	known-to-be-good backend (at the time of this writing, this includes only
1470	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file	1571	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file
1471	descriptors for which non-blocking operation makes no sense (such as	1572	descriptors for which non-blocking operation makes no sense (such as
1472	files) - libev doesn't guarentee any specific behaviour in that case.	1573	files) - libev doesn't guarantee any specific behaviour in that case.
1473		1574
1474	Another thing you have to watch out for is that it is quite easy to	1575	Another thing you have to watch out for is that it is quite easy to
1475	receive "spurious" readiness notifications, that is your callback might	1576	receive "spurious" readiness notifications, that is your callback might
1476	be called with C<EV_READ> but a subsequent C<read>(2) will actually block	1577	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
1477	because there is no data. Not only are some backends known to create a	1578	because there is no data. Not only are some backends known to create a
…		…
1621	...	1722	...
1622	struct ev_loop *loop = ev_default_init (0);	1723	struct ev_loop *loop = ev_default_init (0);
1623	ev_io stdin_readable;	1724	ev_io stdin_readable;
1624	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1725	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1625	ev_io_start (loop, &stdin_readable);	1726	ev_io_start (loop, &stdin_readable);
1626	ev_loop (loop, 0);	1727	ev_run (loop, 0);
1627		1728
1628		1729
1629	=head2 C<ev_timer> - relative and optionally repeating timeouts	1730	=head2 C<ev_timer> - relative and optionally repeating timeouts
1630		1731
1631	Timer watchers are simple relative timers that generate an event after a	1732	Timer watchers are simple relative timers that generate an event after a
…		…
1640	The callback is guaranteed to be invoked only I<after> its timeout has	1741	The callback is guaranteed to be invoked only I<after> its timeout has
1641	passed (not I<at>, so on systems with very low-resolution clocks this	1742	passed (not I<at>, so on systems with very low-resolution clocks this
1642	might introduce a small delay). If multiple timers become ready during the	1743	might introduce a small delay). If multiple timers become ready during the
1643	same loop iteration then the ones with earlier time-out values are invoked	1744	same loop iteration then the ones with earlier time-out values are invoked
1644	before ones of the same priority with later time-out values (but this is	1745	before ones of the same priority with later time-out values (but this is
1645	no longer true when a callback calls C<ev_loop> recursively).	1746	no longer true when a callback calls C<ev_run> recursively).
1646		1747
1647	=head3 Be smart about timeouts	1748	=head3 Be smart about timeouts
1648		1749
1649	Many real-world problems involve some kind of timeout, usually for error	1750	Many real-world problems involve some kind of timeout, usually for error
1650	recovery. A typical example is an HTTP request - if the other side hangs,	1751	recovery. A typical example is an HTTP request - if the other side hangs,
…		…
1736	ev_tstamp timeout = last_activity + 60.;	1837	ev_tstamp timeout = last_activity + 60.;
1737		1838
1738	// if last_activity + 60. is older than now, we did time out	1839	// if last_activity + 60. is older than now, we did time out
1739	if (timeout < now)	1840	if (timeout < now)
1740	{	1841	{
1741	// timeout occured, take action	1842	// timeout occurred, take action
1742	}	1843	}
1743	else	1844	else
1744	{	1845	{
1745	// callback was invoked, but there was some activity, re-arm	1846	// callback was invoked, but there was some activity, re-arm
1746	// the watcher to fire in last_activity + 60, which is	1847	// the watcher to fire in last_activity + 60, which is
…		…
1773	callback (loop, timer, EV_TIMER);	1874	callback (loop, timer, EV_TIMER);
1774		1875
1775	And when there is some activity, simply store the current time in	1876	And when there is some activity, simply store the current time in
1776	C<last_activity>, no libev calls at all:	1877	C<last_activity>, no libev calls at all:
1777		1878
1778	last_actiivty = ev_now (loop);	1879	last_activity = ev_now (loop);
1779		1880
1780	This technique is slightly more complex, but in most cases where the	1881	This technique is slightly more complex, but in most cases where the
1781	time-out is unlikely to be triggered, much more efficient.	1882	time-out is unlikely to be triggered, much more efficient.
1782		1883
1783	Changing the timeout is trivial as well (if it isn't hard-coded in the	1884	Changing the timeout is trivial as well (if it isn't hard-coded in the
…		…
1821		1922
1822	=head3 The special problem of time updates	1923	=head3 The special problem of time updates
1823		1924
1824	Establishing the current time is a costly operation (it usually takes at	1925	Establishing the current time is a costly operation (it usually takes at
1825	least two system calls): EV therefore updates its idea of the current	1926	least two system calls): EV therefore updates its idea of the current
1826	time only before and after C<ev_loop> collects new events, which causes a	1927	time only before and after C<ev_run> collects new events, which causes a
1827	growing difference between C<ev_now ()> and C<ev_time ()> when handling	1928	growing difference between C<ev_now ()> and C<ev_time ()> when handling
1828	lots of events in one iteration.	1929	lots of events in one iteration.
1829		1930
1830	The relative timeouts are calculated relative to the C<ev_now ()>	1931	The relative timeouts are calculated relative to the C<ev_now ()>
1831	time. This is usually the right thing as this timestamp refers to the time	1932	time. This is usually the right thing as this timestamp refers to the time
…		…
1948	}	2049	}
1949		2050
1950	ev_timer mytimer;	2051	ev_timer mytimer;
1951	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	2052	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1952	ev_timer_again (&mytimer); /* start timer */	2053	ev_timer_again (&mytimer); /* start timer */
1953	ev_loop (loop, 0);	2054	ev_run (loop, 0);
1954		2055
1955	// and in some piece of code that gets executed on any "activity":	2056	// and in some piece of code that gets executed on any "activity":
1956	// reset the timeout to start ticking again at 10 seconds	2057	// reset the timeout to start ticking again at 10 seconds
1957	ev_timer_again (&mytimer);	2058	ev_timer_again (&mytimer);
1958		2059
…		…
1984		2085
1985	As with timers, the callback is guaranteed to be invoked only when the	2086	As with timers, the callback is guaranteed to be invoked only when the
1986	point in time where it is supposed to trigger has passed. If multiple	2087	point in time where it is supposed to trigger has passed. If multiple
1987	timers become ready during the same loop iteration then the ones with	2088	timers become ready during the same loop iteration then the ones with
1988	earlier time-out values are invoked before ones with later time-out values	2089	earlier time-out values are invoked before ones with later time-out values
1989	(but this is no longer true when a callback calls C<ev_loop> recursively).	2090	(but this is no longer true when a callback calls C<ev_run> recursively).
1990		2091
1991	=head3 Watcher-Specific Functions and Data Members	2092	=head3 Watcher-Specific Functions and Data Members
1992		2093
1993	=over 4	2094	=over 4
1994		2095
…		…
2122	Example: Call a callback every hour, or, more precisely, whenever the	2223	Example: Call a callback every hour, or, more precisely, whenever the
2123	system time is divisible by 3600. The callback invocation times have	2224	system time is divisible by 3600. The callback invocation times have
2124	potentially a lot of jitter, but good long-term stability.	2225	potentially a lot of jitter, but good long-term stability.
2125		2226
2126	static void	2227	static void
2127	clock_cb (struct ev_loop *loop, ev_io *w, int revents)	2228	clock_cb (struct ev_loop *loop, ev_periodic *w, int revents)
2128	{	2229	{
2129	... its now a full hour (UTC, or TAI or whatever your clock follows)	2230	... its now a full hour (UTC, or TAI or whatever your clock follows)
2130	}	2231	}
2131		2232
2132	ev_periodic hourly_tick;	2233	ev_periodic hourly_tick;
…		…
2232	Example: Try to exit cleanly on SIGINT.	2333	Example: Try to exit cleanly on SIGINT.
2233		2334
2234	static void	2335	static void
2235	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)	2336	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)
2236	{	2337	{
2237	ev_unloop (loop, EVUNLOOP_ALL);	2338	ev_break (loop, EVBREAK_ALL);
2238	}	2339	}
2239		2340
2240	ev_signal signal_watcher;	2341	ev_signal signal_watcher;
2241	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	2342	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
2242	ev_signal_start (loop, &signal_watcher);	2343	ev_signal_start (loop, &signal_watcher);
…		…
2628		2729
2629	Prepare and check watchers are usually (but not always) used in pairs:	2730	Prepare and check watchers are usually (but not always) used in pairs:
2630	prepare watchers get invoked before the process blocks and check watchers	2731	prepare watchers get invoked before the process blocks and check watchers
2631	afterwards.	2732	afterwards.
2632		2733
2633	You I<must not> call C<ev_loop> or similar functions that enter	2734	You I<must not> call C<ev_run> or similar functions that enter
2634	the current event loop from either C<ev_prepare> or C<ev_check>	2735	the current event loop from either C<ev_prepare> or C<ev_check>
2635	watchers. Other loops than the current one are fine, however. The	2736	watchers. Other loops than the current one are fine, however. The
2636	rationale behind this is that you do not need to check for recursion in	2737	rationale behind this is that you do not need to check for recursion in
2637	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,	2738	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,
2638	C<ev_check> so if you have one watcher of each kind they will always be	2739	C<ev_check> so if you have one watcher of each kind they will always be
…		…
2806		2907
2807	if (timeout >= 0)	2908	if (timeout >= 0)
2808	// create/start timer	2909	// create/start timer
2809		2910
2810	// poll	2911	// poll
2811	ev_loop (EV_A_ 0);	2912	ev_run (EV_A_ 0);
2812		2913
2813	// stop timer again	2914	// stop timer again
2814	if (timeout >= 0)	2915	if (timeout >= 0)
2815	ev_timer_stop (EV_A_ &to);	2916	ev_timer_stop (EV_A_ &to);
2816		2917
…		…
2894	if you do not want that, you need to temporarily stop the embed watcher).	2995	if you do not want that, you need to temporarily stop the embed watcher).
2895		2996
2896	=item ev_embed_sweep (loop, ev_embed *)	2997	=item ev_embed_sweep (loop, ev_embed *)
2897		2998
2898	Make a single, non-blocking sweep over the embedded loop. This works	2999	Make a single, non-blocking sweep over the embedded loop. This works
2899	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	3000	similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most
2900	appropriate way for embedded loops.	3001	appropriate way for embedded loops.
2901		3002
2902	=item struct ev_loop *other [read-only]	3003	=item struct ev_loop *other [read-only]
2903		3004
2904	The embedded event loop.	3005	The embedded event loop.
…		…
2964	C<ev_default_fork> cheats and calls it in the wrong process, the fork	3065	C<ev_default_fork> cheats and calls it in the wrong process, the fork
2965	handlers will be invoked, too, of course.	3066	handlers will be invoked, too, of course.
2966		3067
2967	=head3 The special problem of life after fork - how is it possible?	3068	=head3 The special problem of life after fork - how is it possible?
2968		3069
2969	Most uses of C<fork()> consist of forking, then some simple calls to ste	3070	Most uses of C<fork()> consist of forking, then some simple calls to set
2970	up/change the process environment, followed by a call to C<exec()>. This	3071	up/change the process environment, followed by a call to C<exec()>. This
2971	sequence should be handled by libev without any problems.	3072	sequence should be handled by libev without any problems.
2972		3073
2973	This changes when the application actually wants to do event handling	3074	This changes when the application actually wants to do event handling
2974	in the child, or both parent in child, in effect "continuing" after the	3075	in the child, or both parent in child, in effect "continuing" after the
…		…
2990	disadvantage of having to use multiple event loops (which do not support	3091	disadvantage of having to use multiple event loops (which do not support
2991	signal watchers).	3092	signal watchers).
2992		3093
2993	When this is not possible, or you want to use the default loop for	3094	When this is not possible, or you want to use the default loop for
2994	other reasons, then in the process that wants to start "fresh", call	3095	other reasons, then in the process that wants to start "fresh", call
2995	C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying	3096	C<ev_loop_destroy (EV_DEFAULT)> followed by C<ev_default_loop (...)>.
2996	the default loop will "orphan" (not stop) all registered watchers, so you	3097	Destroying the default loop will "orphan" (not stop) all registered
2997	have to be careful not to execute code that modifies those watchers. Note	3098	watchers, so you have to be careful not to execute code that modifies
2998	also that in that case, you have to re-register any signal watchers.	3099	those watchers. Note also that in that case, you have to re-register any
		3100	signal watchers.
2999		3101
3000	=head3 Watcher-Specific Functions and Data Members	3102	=head3 Watcher-Specific Functions and Data Members
3001		3103
3002	=over 4	3104	=over 4
3003		3105
3004	=item ev_fork_init (ev_signal *, callback)	3106	=item ev_fork_init (ev_fork *, callback)
3005		3107
3006	Initialises and configures the fork watcher - it has no parameters of any	3108	Initialises and configures the fork watcher - it has no parameters of any
3007	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,	3109	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
3008	believe me.	3110	really.
3009		3111
3010	=back	3112	=back
3011		3113
3012		3114
		3115	=head2 C<ev_cleanup> - even the best things end
		3116
		3117	Cleanup watchers are called just before the event loop is being destroyed
		3118	by a call to C<ev_loop_destroy>.
		3119
		3120	While there is no guarantee that the event loop gets destroyed, cleanup
		3121	watchers provide a convenient method to install cleanup hooks for your
		3122	program, worker threads and so on - you just to make sure to destroy the
		3123	loop when you want them to be invoked.
		3124
		3125	Cleanup watchers are invoked in the same way as any other watcher. Unlike
		3126	all other watchers, they do not keep a reference to the event loop (which
		3127	makes a lot of sense if you think about it). Like all other watchers, you
		3128	can call libev functions in the callback, except C<ev_cleanup_start>.
		3129
		3130	=head3 Watcher-Specific Functions and Data Members
		3131
		3132	=over 4
		3133
		3134	=item ev_cleanup_init (ev_cleanup *, callback)
		3135
		3136	Initialises and configures the cleanup watcher - it has no parameters of
		3137	any kind. There is a C<ev_cleanup_set> macro, but using it is utterly
		3138	pointless, I assure you.
		3139
		3140	=back
		3141
		3142	Example: Register an atexit handler to destroy the default loop, so any
		3143	cleanup functions are called.
		3144
		3145	static void
		3146	program_exits (void)
		3147	{
		3148	ev_loop_destroy (EV_DEFAULT_UC);
		3149	}
		3150
		3151	...
		3152	atexit (program_exits);
		3153
		3154
3013	=head2 C<ev_async> - how to wake up another event loop	3155	=head2 C<ev_async> - how to wake up an event loop
3014		3156
3015	In general, you cannot use an C<ev_loop> from multiple threads or other	3157	In general, you cannot use an C<ev_run> from multiple threads or other
3016	asynchronous sources such as signal handlers (as opposed to multiple event	3158	asynchronous sources such as signal handlers (as opposed to multiple event
3017	loops - those are of course safe to use in different threads).	3159	loops - those are of course safe to use in different threads).
3018		3160
3019	Sometimes, however, you need to wake up another event loop you do not	3161	Sometimes, however, you need to wake up an event loop you do not control,
3020	control, for example because it belongs to another thread. This is what	3162	for example because it belongs to another thread. This is what C<ev_async>
3021	C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you	3163	watchers do: as long as the C<ev_async> watcher is active, you can signal
3022	can signal it by calling C<ev_async_send>, which is thread- and signal	3164	it by calling C<ev_async_send>, which is thread- and signal safe.
3023	safe.
3024		3165
3025	This functionality is very similar to C<ev_signal> watchers, as signals,	3166	This functionality is very similar to C<ev_signal> watchers, as signals,
3026	too, are asynchronous in nature, and signals, too, will be compressed	3167	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	3168	(i.e. the number of callback invocations may be less than the number of
3028	C<ev_async_sent> calls).	3169	C<ev_async_sent> calls).
…		…
3340	myclass obj;	3481	myclass obj;
3341	ev::io iow;	3482	ev::io iow;
3342	iow.set <myclass, &myclass::io_cb> (&obj);	3483	iow.set <myclass, &myclass::io_cb> (&obj);
3343		3484
3344	=item w->set (object *)	3485	=item w->set (object *)
3345
3346	This is an B<experimental> feature that might go away in a future version.
3347		3486
3348	This is a variation of a method callback - leaving out the method to call	3487	This is a variation of a method callback - leaving out the method to call
3349	will default the method to C<operator ()>, which makes it possible to use	3488	will default the method to C<operator ()>, which makes it possible to use
3350	functor objects without having to manually specify the C<operator ()> all	3489	functor objects without having to manually specify the C<operator ()> all
3351	the time. Incidentally, you can then also leave out the template argument	3490	the time. Incidentally, you can then also leave out the template argument
…		…
3391	Associates a different C<struct ev_loop> with this watcher. You can only	3530	Associates a different C<struct ev_loop> with this watcher. You can only
3392	do this when the watcher is inactive (and not pending either).	3531	do this when the watcher is inactive (and not pending either).
3393		3532
3394	=item w->set ([arguments])	3533	=item w->set ([arguments])
3395		3534
3396	Basically the same as C<ev_TYPE_set>, with the same arguments. Must be	3535	Basically the same as C<ev_TYPE_set>, with the same arguments. Either this
3397	called at least once. Unlike the C counterpart, an active watcher gets	3536	method or a suitable start method must be called at least once. Unlike the
3398	automatically stopped and restarted when reconfiguring it with this	3537	C counterpart, an active watcher gets automatically stopped and restarted
3399	method.	3538	when reconfiguring it with this method.
3400		3539
3401	=item w->start ()	3540	=item w->start ()
3402		3541
3403	Starts the watcher. Note that there is no C<loop> argument, as the	3542	Starts the watcher. Note that there is no C<loop> argument, as the
3404	constructor already stores the event loop.	3543	constructor already stores the event loop.
3405		3544
		3545	=item w->start ([arguments])
		3546
		3547	Instead of calling C<set> and C<start> methods separately, it is often
		3548	convenient to wrap them in one call. Uses the same type of arguments as
		3549	the configure C<set> method of the watcher.
		3550
3406	=item w->stop ()	3551	=item w->stop ()
3407		3552
3408	Stops the watcher if it is active. Again, no C<loop> argument.	3553	Stops the watcher if it is active. Again, no C<loop> argument.
3409		3554
3410	=item w->again () (C<ev::timer>, C<ev::periodic> only)	3555	=item w->again () (C<ev::timer>, C<ev::periodic> only)
…		…
3422		3567
3423	=back	3568	=back
3424		3569
3425	=back	3570	=back
3426		3571
3427	Example: Define a class with an IO and idle watcher, start one of them in	3572	Example: Define a class with two I/O and idle watchers, start the I/O
3428	the constructor.	3573	watchers in the constructor.
3429		3574
3430	class myclass	3575	class myclass
3431	{	3576	{
3432	ev::io io ; void io_cb (ev::io &w, int revents);	3577	ev::io io ; void io_cb (ev::io &w, int revents);
		3578	ev::io2 io2 ; void io2_cb (ev::io &w, int revents);
3433	ev::idle idle; void idle_cb (ev::idle &w, int revents);	3579	ev::idle idle; void idle_cb (ev::idle &w, int revents);
3434		3580
3435	myclass (int fd)	3581	myclass (int fd)
3436	{	3582	{
3437	io .set <myclass, &myclass::io_cb > (this);	3583	io .set <myclass, &myclass::io_cb > (this);
		3584	io2 .set <myclass, &myclass::io2_cb > (this);
3438	idle.set <myclass, &myclass::idle_cb> (this);	3585	idle.set <myclass, &myclass::idle_cb> (this);
3439		3586
3440	io.start (fd, ev::READ);	3587	io.set (fd, ev::WRITE); // configure the watcher
		3588	io.start (); // start it whenever convenient
		3589
		3590	io2.start (fd, ev::READ); // set + start in one call
3441	}	3591	}
3442	};	3592	};
3443		3593
3444		3594
3445	=head1 OTHER LANGUAGE BINDINGS	3595	=head1 OTHER LANGUAGE BINDINGS
…		…
3519	loop argument"). The C<EV_A> form is used when this is the sole argument,	3669	loop argument"). The C<EV_A> form is used when this is the sole argument,
3520	C<EV_A_> is used when other arguments are following. Example:	3670	C<EV_A_> is used when other arguments are following. Example:
3521		3671
3522	ev_unref (EV_A);	3672	ev_unref (EV_A);
3523	ev_timer_add (EV_A_ watcher);	3673	ev_timer_add (EV_A_ watcher);
3524	ev_loop (EV_A_ 0);	3674	ev_run (EV_A_ 0);
3525		3675
3526	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	3676	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
3527	which is often provided by the following macro.	3677	which is often provided by the following macro.
3528		3678
3529	=item C<EV_P>, C<EV_P_>	3679	=item C<EV_P>, C<EV_P_>
…		…
3569	}	3719	}
3570		3720
3571	ev_check check;	3721	ev_check check;
3572	ev_check_init (&check, check_cb);	3722	ev_check_init (&check, check_cb);
3573	ev_check_start (EV_DEFAULT_ &check);	3723	ev_check_start (EV_DEFAULT_ &check);
3574	ev_loop (EV_DEFAULT_ 0);	3724	ev_run (EV_DEFAULT_ 0);
3575		3725
3576	=head1 EMBEDDING	3726	=head1 EMBEDDING
3577		3727
3578	Libev can (and often is) directly embedded into host	3728	Libev can (and often is) directly embedded into host
3579	applications. Examples of applications that embed it include the Deliantra	3729	applications. Examples of applications that embed it include the Deliantra
…		…
3670	to a compiled library. All other symbols change the ABI, which means all	3820	to a compiled library. All other symbols change the ABI, which means all
3671	users of libev and the libev code itself must be compiled with compatible	3821	users of libev and the libev code itself must be compiled with compatible
3672	settings.	3822	settings.
3673		3823
3674	=over 4	3824	=over 4
		3825
		3826	=item EV_COMPAT3 (h)
		3827
		3828	Backwards compatibility is a major concern for libev. This is why this
		3829	release of libev comes with wrappers for the functions and symbols that
		3830	have been renamed between libev version 3 and 4.
		3831
		3832	You can disable these wrappers (to test compatibility with future
		3833	versions) by defining C<EV_COMPAT3> to C<0> when compiling your
		3834	sources. This has the additional advantage that you can drop the C<struct>
		3835	from C<struct ev_loop> declarations, as libev will provide an C<ev_loop>
		3836	typedef in that case.
		3837
		3838	In some future version, the default for C<EV_COMPAT3> will become C<0>,
		3839	and in some even more future version the compatibility code will be
		3840	removed completely.
3675		3841
3676	=item EV_STANDALONE (h)	3842	=item EV_STANDALONE (h)
3677		3843
3678	Must always be C<1> if you do not use autoconf configuration, which	3844	Must always be C<1> if you do not use autoconf configuration, which
3679	keeps libev from including F<config.h>, and it also defines dummy	3845	keeps libev from including F<config.h>, and it also defines dummy
…		…
3886	EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE,	4052	EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE,
3887	EV_ASYNC_ENABLE, EV_CHILD_ENABLE.	4053	EV_ASYNC_ENABLE, EV_CHILD_ENABLE.
3888		4054
3889	If undefined or defined to be C<1> (and the platform supports it), then	4055	If undefined or defined to be C<1> (and the platform supports it), then
3890	the respective watcher type is supported. If defined to be C<0>, then it	4056	the respective watcher type is supported. If defined to be C<0>, then it
3891	is not. Disabling watcher types mainly saves codesize.	4057	is not. Disabling watcher types mainly saves code size.
3892		4058
3893	=item EV_FEATURES	4059	=item EV_FEATURES
3894		4060
3895	If you need to shave off some kilobytes of code at the expense of some	4061	If you need to shave off some kilobytes of code at the expense of some
3896	speed (but with the full API), you can define this symbol to request	4062	speed (but with the full API), you can define this symbol to request
…		…
3916		4082
3917	=item C<1> - faster/larger code	4083	=item C<1> - faster/larger code
3918		4084
3919	Use larger code to speed up some operations.	4085	Use larger code to speed up some operations.
3920		4086
3921	Currently this is used to override some inlining decisions (enlarging the roughly	4087	Currently this is used to override some inlining decisions (enlarging the
3922	30% code size on amd64.	4088	code size by roughly 30% on amd64).
3923		4089
3924	When optimising for size, use of compiler flags such as C<-Os> with	4090	When optimising for size, use of compiler flags such as C<-Os> with
3925	gcc recommended, as well as C<-DNDEBUG>, as libev contains a number of	4091	gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of
3926	assertions.	4092	assertions.
3927		4093
3928	=item C<2> - faster/larger data structures	4094	=item C<2> - faster/larger data structures
3929		4095
3930	Replaces the small 2-heap for timer management by a faster 4-heap, larger	4096	Replaces the small 2-heap for timer management by a faster 4-heap, larger
3931	hash table sizes and so on. This will usually further increase codesize	4097	hash table sizes and so on. This will usually further increase code size
3932	and can additionally have an effect on the size of data structures at	4098	and can additionally have an effect on the size of data structures at
3933	runtime.	4099	runtime.
3934		4100
3935	=item C<4> - full API configuration	4101	=item C<4> - full API configuration
3936		4102
…		…
3973	I/O watcher then might come out at only 5Kb.	4139	I/O watcher then might come out at only 5Kb.
3974		4140
3975	=item EV_AVOID_STDIO	4141	=item EV_AVOID_STDIO
3976		4142
3977	If this is set to C<1> at compiletime, then libev will avoid using stdio	4143	If this is set to C<1> at compiletime, then libev will avoid using stdio
3978	functions (printf, scanf, perror etc.). This will increase the codesize	4144	functions (printf, scanf, perror etc.). This will increase the code size
3979	somewhat, but if your program doesn't otherwise depend on stdio and your	4145	somewhat, but if your program doesn't otherwise depend on stdio and your
3980	libc allows it, this avoids linking in the stdio library which is quite	4146	libc allows it, this avoids linking in the stdio library which is quite
3981	big.	4147	big.
3982		4148
3983	Note that error messages might become less precise when this option is	4149	Note that error messages might become less precise when this option is
…		…
3987		4153
3988	The highest supported signal number, +1 (or, the number of	4154	The highest supported signal number, +1 (or, the number of
3989	signals): Normally, libev tries to deduce the maximum number of signals	4155	signals): Normally, libev tries to deduce the maximum number of signals
3990	automatically, but sometimes this fails, in which case it can be	4156	automatically, but sometimes this fails, in which case it can be
3991	specified. Also, using a lower number than detected (C<32> should be	4157	specified. Also, using a lower number than detected (C<32> should be
3992	good for about any system in existance) can save some memory, as libev	4158	good for about any system in existence) can save some memory, as libev
3993	statically allocates some 12-24 bytes per signal number.	4159	statically allocates some 12-24 bytes per signal number.
3994		4160
3995	=item EV_PID_HASHSIZE	4161	=item EV_PID_HASHSIZE
3996		4162
3997	C<ev_child> watchers use a small hash table to distribute workload by	4163	C<ev_child> watchers use a small hash table to distribute workload by
…		…
4029	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it	4195	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
4030	will be C<0>.	4196	will be C<0>.
4031		4197
4032	=item EV_VERIFY	4198	=item EV_VERIFY
4033		4199
4034	Controls how much internal verification (see C<ev_loop_verify ()>) will	4200	Controls how much internal verification (see C<ev_verify ()>) will
4035	be done: If set to C<0>, no internal verification code will be compiled	4201	be done: If set to C<0>, no internal verification code will be compiled
4036	in. If set to C<1>, then verification code will be compiled in, but not	4202	in. If set to C<1>, then verification code will be compiled in, but not
4037	called. If set to C<2>, then the internal verification code will be	4203	called. If set to C<2>, then the internal verification code will be
4038	called once per loop, which can slow down libev. If set to C<3>, then the	4204	called once per loop, which can slow down libev. If set to C<3>, then the
4039	verification code will be called very frequently, which will slow down	4205	verification code will be called very frequently, which will slow down
…		…
4043	will be C<0>.	4209	will be C<0>.
4044		4210
4045	=item EV_COMMON	4211	=item EV_COMMON
4046		4212
4047	By default, all watchers have a C<void *data> member. By redefining	4213	By default, all watchers have a C<void *data> member. By redefining
4048	this macro to a something else you can include more and other types of	4214	this macro to something else you can include more and other types of
4049	members. You have to define it each time you include one of the files,	4215	members. You have to define it each time you include one of the files,
4050	though, and it must be identical each time.	4216	though, and it must be identical each time.
4051		4217
4052	For example, the perl EV module uses something like this:	4218	For example, the perl EV module uses something like this:
4053		4219
…		…
4254	userdata *u = ev_userdata (EV_A);	4420	userdata *u = ev_userdata (EV_A);
4255	pthread_mutex_lock (&u->lock);	4421	pthread_mutex_lock (&u->lock);
4256	}	4422	}
4257		4423
4258	The event loop thread first acquires the mutex, and then jumps straight	4424	The event loop thread first acquires the mutex, and then jumps straight
4259	into C<ev_loop>:	4425	into C<ev_run>:
4260		4426
4261	void *	4427	void *
4262	l_run (void *thr_arg)	4428	l_run (void *thr_arg)
4263	{	4429	{
4264	struct ev_loop *loop = (struct ev_loop *)thr_arg;	4430	struct ev_loop *loop = (struct ev_loop *)thr_arg;
4265		4431
4266	l_acquire (EV_A);	4432	l_acquire (EV_A);
4267	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);	4433	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
4268	ev_loop (EV_A_ 0);	4434	ev_run (EV_A_ 0);
4269	l_release (EV_A);	4435	l_release (EV_A);
4270		4436
4271	return 0;	4437	return 0;
4272	}	4438	}
4273		4439
…		…
4325		4491
4326	=head3 COROUTINES	4492	=head3 COROUTINES
4327		4493
4328	Libev is very accommodating to coroutines ("cooperative threads"):	4494	Libev is very accommodating to coroutines ("cooperative threads"):
4329	libev fully supports nesting calls to its functions from different	4495	libev fully supports nesting calls to its functions from different
4330	coroutines (e.g. you can call C<ev_loop> on the same loop from two	4496	coroutines (e.g. you can call C<ev_run> on the same loop from two
4331	different coroutines, and switch freely between both coroutines running	4497	different coroutines, and switch freely between both coroutines running
4332	the loop, as long as you don't confuse yourself). The only exception is	4498	the loop, as long as you don't confuse yourself). The only exception is
4333	that you must not do this from C<ev_periodic> reschedule callbacks.	4499	that you must not do this from C<ev_periodic> reschedule callbacks.
4334		4500
4335	Care has been taken to ensure that libev does not keep local state inside	4501	Care has been taken to ensure that libev does not keep local state inside
4336	C<ev_loop>, and other calls do not usually allow for coroutine switches as	4502	C<ev_run>, and other calls do not usually allow for coroutine switches as
4337	they do not call any callbacks.	4503	they do not call any callbacks.
4338		4504
4339	=head2 COMPILER WARNINGS	4505	=head2 COMPILER WARNINGS
4340		4506
4341	Depending on your compiler and compiler settings, you might get no or a	4507	Depending on your compiler and compiler settings, you might get no or a
…		…
4352	maintainable.	4518	maintainable.
4353		4519
4354	And of course, some compiler warnings are just plain stupid, or simply	4520	And of course, some compiler warnings are just plain stupid, or simply
4355	wrong (because they don't actually warn about the condition their message	4521	wrong (because they don't actually warn about the condition their message
4356	seems to warn about). For example, certain older gcc versions had some	4522	seems to warn about). For example, certain older gcc versions had some
4357	warnings that resulted an extreme number of false positives. These have	4523	warnings that resulted in an extreme number of false positives. These have
4358	been fixed, but some people still insist on making code warn-free with	4524	been fixed, but some people still insist on making code warn-free with
4359	such buggy versions.	4525	such buggy versions.
4360		4526
4361	While libev is written to generate as few warnings as possible,	4527	While libev is written to generate as few warnings as possible,
4362	"warn-free" code is not a goal, and it is recommended not to build libev	4528	"warn-free" code is not a goal, and it is recommended not to build libev
…		…
4398	I suggest using suppression lists.	4564	I suggest using suppression lists.
4399		4565
4400		4566
4401	=head1 PORTABILITY NOTES	4567	=head1 PORTABILITY NOTES
4402		4568
		4569	=head2 GNU/LINUX 32 BIT LIMITATIONS
		4570
		4571	GNU/Linux is the only common platform that supports 64 bit file/large file
		4572	interfaces but I<disables> them by default.
		4573
		4574	That means that libev compiled in the default environment doesn't support
		4575	files larger than 2GiB or so, which mainly affects C<ev_stat> watchers.
		4576
		4577	Unfortunately, many programs try to work around this GNU/Linux issue
		4578	by enabling the large file API, which makes them incompatible with the
		4579	standard libev compiled for their system.
		4580
		4581	Likewise, libev cannot enable the large file API itself as this would
		4582	suddenly make it incompatible to the default compile time environment,
		4583	i.e. all programs not using special compile switches.
		4584
		4585	=head2 OS/X AND DARWIN BUGS
		4586
		4587	The whole thing is a bug if you ask me - basically any system interface
		4588	you touch is broken, whether it is locales, poll, kqueue or even the
		4589	OpenGL drivers.
		4590
		4591	=head3 C<kqueue> is buggy
		4592
		4593	The kqueue syscall is broken in all known versions - most versions support
		4594	only sockets, many support pipes.
		4595
		4596	Libev tries to work around this by not using C<kqueue> by default on this
		4597	rotten platform, but of course you can still ask for it when creating a
		4598	loop - embedding a socket-only kqueue loop into a select-based one is
		4599	probably going to work well.
		4600
		4601	=head3 C<poll> is buggy
		4602
		4603	Instead of fixing C<kqueue>, Apple replaced their (working) C<poll>
		4604	implementation by something calling C<kqueue> internally around the 10.5.6
		4605	release, so now C<kqueue> I<and> C<poll> are broken.
		4606
		4607	Libev tries to work around this by not using C<poll> by default on
		4608	this rotten platform, but of course you can still ask for it when creating
		4609	a loop.
		4610
		4611	=head3 C<select> is buggy
		4612
		4613	All that's left is C<select>, and of course Apple found a way to fuck this
		4614	one up as well: On OS/X, C<select> actively limits the number of file
		4615	descriptors you can pass in to 1024 - your program suddenly crashes when
		4616	you use more.
		4617
		4618	There is an undocumented "workaround" for this - defining
		4619	C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should>
		4620	work on OS/X.
		4621
		4622	=head2 SOLARIS PROBLEMS AND WORKAROUNDS
		4623
		4624	=head3 C<errno> reentrancy
		4625
		4626	The default compile environment on Solaris is unfortunately so
		4627	thread-unsafe that you can't even use components/libraries compiled
		4628	without C<-D_REENTRANT> in a threaded program, which, of course, isn't
		4629	defined by default. A valid, if stupid, implementation choice.
		4630
		4631	If you want to use libev in threaded environments you have to make sure
		4632	it's compiled with C<_REENTRANT> defined.
		4633
		4634	=head3 Event port backend
		4635
		4636	The scalable event interface for Solaris is called "event
		4637	ports". Unfortunately, this mechanism is very buggy in all major
		4638	releases. If you run into high CPU usage, your program freezes or you get
		4639	a large number of spurious wakeups, make sure you have all the relevant
		4640	and latest kernel patches applied. No, I don't know which ones, but there
		4641	are multiple ones to apply, and afterwards, event ports actually work
		4642	great.
		4643
		4644	If you can't get it to work, you can try running the program by setting
		4645	the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and
		4646	C<select> backends.
		4647
		4648	=head2 AIX POLL BUG
		4649
		4650	AIX unfortunately has a broken C<poll.h> header. Libev works around
		4651	this by trying to avoid the poll backend altogether (i.e. it's not even
		4652	compiled in), which normally isn't a big problem as C<select> works fine
		4653	with large bitsets on AIX, and AIX is dead anyway.
		4654
4403	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS	4655	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
		4656
		4657	=head3 General issues
4404		4658
4405	Win32 doesn't support any of the standards (e.g. POSIX) that libev	4659	Win32 doesn't support any of the standards (e.g. POSIX) that libev
4406	requires, and its I/O model is fundamentally incompatible with the POSIX	4660	requires, and its I/O model is fundamentally incompatible with the POSIX
4407	model. Libev still offers limited functionality on this platform in	4661	model. Libev still offers limited functionality on this platform in
4408	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	4662	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
4409	descriptors. This only applies when using Win32 natively, not when using	4663	descriptors. This only applies when using Win32 natively, not when using
4410	e.g. cygwin.	4664	e.g. cygwin. Actually, it only applies to the microsofts own compilers,
		4665	as every compielr comes with a slightly differently broken/incompatible
		4666	environment.
4411		4667
4412	Lifting these limitations would basically require the full	4668	Lifting these limitations would basically require the full
4413	re-implementation of the I/O system. If you are into these kinds of	4669	re-implementation of the I/O system. If you are into this kind of thing,
4414	things, then note that glib does exactly that for you in a very portable	4670	then note that glib does exactly that for you in a very portable way (note
4415	way (note also that glib is the slowest event library known to man).	4671	also that glib is the slowest event library known to man).
4416		4672
4417	There is no supported compilation method available on windows except	4673	There is no supported compilation method available on windows except
4418	embedding it into other applications.	4674	embedding it into other applications.
4419		4675
4420	Sensible signal handling is officially unsupported by Microsoft - libev	4676	Sensible signal handling is officially unsupported by Microsoft - libev
…		…
4448	you do I<not> compile the F<ev.c> or any other embedded source files!):	4704	you do I<not> compile the F<ev.c> or any other embedded source files!):
4449		4705
4450	#include "evwrap.h"	4706	#include "evwrap.h"
4451	#include "ev.c"	4707	#include "ev.c"
4452		4708
4453	=over 4
4454
4455	=item The winsocket select function	4709	=head3 The winsocket C<select> function
4456		4710
4457	The winsocket C<select> function doesn't follow POSIX in that it	4711	The winsocket C<select> function doesn't follow POSIX in that it
4458	requires socket I<handles> and not socket I<file descriptors> (it is	4712	requires socket I<handles> and not socket I<file descriptors> (it is
4459	also extremely buggy). This makes select very inefficient, and also	4713	also extremely buggy). This makes select very inefficient, and also
4460	requires a mapping from file descriptors to socket handles (the Microsoft	4714	requires a mapping from file descriptors to socket handles (the Microsoft
…		…
4469	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */	4723	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
4470		4724
4471	Note that winsockets handling of fd sets is O(n), so you can easily get a	4725	Note that winsockets handling of fd sets is O(n), so you can easily get a
4472	complexity in the O(n²) range when using win32.	4726	complexity in the O(n²) range when using win32.
4473		4727
4474	=item Limited number of file descriptors	4728	=head3 Limited number of file descriptors
4475		4729
4476	Windows has numerous arbitrary (and low) limits on things.	4730	Windows has numerous arbitrary (and low) limits on things.
4477		4731
4478	Early versions of winsocket's select only supported waiting for a maximum	4732	Early versions of winsocket's select only supported waiting for a maximum
4479	of C<64> handles (probably owning to the fact that all windows kernels	4733	of C<64> handles (probably owning to the fact that all windows kernels
…		…
4494	runtime libraries. This might get you to about C<512> or C<2048> sockets	4748	runtime libraries. This might get you to about C<512> or C<2048> sockets
4495	(depending on windows version and/or the phase of the moon). To get more,	4749	(depending on windows version and/or the phase of the moon). To get more,
4496	you need to wrap all I/O functions and provide your own fd management, but	4750	you need to wrap all I/O functions and provide your own fd management, but
4497	the cost of calling select (O(n²)) will likely make this unworkable.	4751	the cost of calling select (O(n²)) will likely make this unworkable.
4498		4752
4499	=back
4500
4501	=head2 PORTABILITY REQUIREMENTS	4753	=head2 PORTABILITY REQUIREMENTS
4502		4754
4503	In addition to a working ISO-C implementation and of course the	4755	In addition to a working ISO-C implementation and of course the
4504	backend-specific APIs, libev relies on a few additional extensions:	4756	backend-specific APIs, libev relies on a few additional extensions:
4505		4757
…		…
4511	Libev assumes not only that all watcher pointers have the same internal	4763	Libev assumes not only that all watcher pointers have the same internal
4512	structure (guaranteed by POSIX but not by ISO C for example), but it also	4764	structure (guaranteed by POSIX but not by ISO C for example), but it also
4513	assumes that the same (machine) code can be used to call any watcher	4765	assumes that the same (machine) code can be used to call any watcher
4514	callback: The watcher callbacks have different type signatures, but libev	4766	callback: The watcher callbacks have different type signatures, but libev
4515	calls them using an C<ev_watcher *> internally.	4767	calls them using an C<ev_watcher *> internally.
		4768
		4769	=item pointer accesses must be thread-atomic
		4770
		4771	Accessing a pointer value must be atomic, it must both be readable and
		4772	writable in one piece - this is the case on all current architectures.
4516		4773
4517	=item C<sig_atomic_t volatile> must be thread-atomic as well	4774	=item C<sig_atomic_t volatile> must be thread-atomic as well
4518		4775
4519	The type C<sig_atomic_t volatile> (or whatever is defined as	4776	The type C<sig_atomic_t volatile> (or whatever is defined as
4520	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different	4777	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different
…		…
4543	watchers.	4800	watchers.
4544		4801
4545	=item C<double> must hold a time value in seconds with enough accuracy	4802	=item C<double> must hold a time value in seconds with enough accuracy
4546		4803
4547	The type C<double> is used to represent timestamps. It is required to	4804	The type C<double> is used to represent timestamps. It is required to
4548	have at least 51 bits of mantissa (and 9 bits of exponent), which is good	4805	have at least 51 bits of mantissa (and 9 bits of exponent), which is
4549	enough for at least into the year 4000. This requirement is fulfilled by	4806	good enough for at least into the year 4000 with millisecond accuracy
		4807	(the design goal for libev). This requirement is overfulfilled by
4550	implementations implementing IEEE 754, which is basically all existing	4808	implementations using IEEE 754, which is basically all existing ones. With
4551	ones. With IEEE 754 doubles, you get microsecond accuracy until at least	4809	IEEE 754 doubles, you get microsecond accuracy until at least 2200.
4552	2200.
4553		4810
4554	=back	4811	=back
4555		4812
4556	If you know of other additional requirements drop me a note.	4813	If you know of other additional requirements drop me a note.
4557		4814
…		…
4627	=back	4884	=back
4628		4885
4629		4886
4630	=head1 PORTING FROM LIBEV 3.X TO 4.X	4887	=head1 PORTING FROM LIBEV 3.X TO 4.X
4631		4888
4632	The major version 4 introduced some minor incompatible changes to the API.	4889	The major version 4 introduced some incompatible changes to the API.
4633		4890
4634	At the moment, the C<ev.h> header file tries to implement superficial	4891	At the moment, the C<ev.h> header file provides compatibility definitions
4635	compatibility, so most programs should still compile. Those might be	4892	for all changes, so most programs should still compile. The compatibility
4636	removed in later versions of libev, so better update early than late.	4893	layer might be removed in later versions of libev, so better update to the
		4894	new API early than late.
4637		4895
4638	=over 4	4896	=over 4
4639		4897
4640	=item C<ev_loop_count> renamed to C<ev_iteration>	4898	=item C<EV_COMPAT3> backwards compatibility mechanism
4641		4899
4642	=item C<ev_loop_depth> renamed to C<ev_depth>	4900	The backward compatibility mechanism can be controlled by
		4901	C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING>
		4902	section.
4643		4903
4644	=item C<ev_loop_verify> renamed to C<ev_verify>	4904	=item C<ev_default_destroy> and C<ev_default_fork> have been removed
		4905
		4906	These calls can be replaced easily by their C<ev_loop_xxx> counterparts:
		4907
		4908	ev_loop_destroy (EV_DEFAULT_UC);
		4909	ev_loop_fork (EV_DEFAULT);
		4910
		4911	=item function/symbol renames
		4912
		4913	A number of functions and symbols have been renamed:
		4914
		4915	ev_loop => ev_run
		4916	EVLOOP_NONBLOCK => EVRUN_NOWAIT
		4917	EVLOOP_ONESHOT => EVRUN_ONCE
		4918
		4919	ev_unloop => ev_break
		4920	EVUNLOOP_CANCEL => EVBREAK_CANCEL
		4921	EVUNLOOP_ONE => EVBREAK_ONE
		4922	EVUNLOOP_ALL => EVBREAK_ALL
		4923
		4924	EV_TIMEOUT => EV_TIMER
		4925
		4926	ev_loop_count => ev_iteration
		4927	ev_loop_depth => ev_depth
		4928	ev_loop_verify => ev_verify
4645		4929
4646	Most functions working on C<struct ev_loop> objects don't have an	4930	Most functions working on C<struct ev_loop> objects don't have an
4647	C<ev_loop_> prefix, so it was removed. Note that C<ev_loop_fork> is	4931	C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and
		4932	associated constants have been renamed to not collide with the C<struct
		4933	ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme
		4934	as all other watcher types. Note that C<ev_loop_fork> is still called
4648	still called C<ev_loop_fork> because it would otherwise clash with the	4935	C<ev_loop_fork> because it would otherwise clash with the C<ev_fork>
4649	C<ev_fork> typedef.	4936	typedef.
4650
4651	=item C<EV_TIMEOUT> renamed to C<EV_TIMER> in C<revents>
4652
4653	This is a simple rename - all other watcher types use their name
4654	as revents flag, and now C<ev_timer> does, too.
4655
4656	Both C<EV_TIMER> and C<EV_TIMEOUT> symbols were present in 3.x versions
4657	and continue to be present for the forseeable future, so this is mostly a
4658	documentation change.
4659		4937
4660	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>	4938	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>
4661		4939
4662	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different	4940	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different
4663	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile	4941	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile
…		…
4670		4948
4671	=over 4	4949	=over 4
4672		4950
4673	=item active	4951	=item active
4674		4952
4675	A watcher is active as long as it has been started (has been attached to	4953	A watcher is active as long as it has been started and not yet stopped.
4676	an event loop) but not yet stopped (disassociated from the event loop).	4954	See L<WATCHER STATES> for details.
4677		4955
4678	=item application	4956	=item application
4679		4957
4680	In this document, an application is whatever is using libev.	4958	In this document, an application is whatever is using libev.
		4959
		4960	=item backend
		4961
		4962	The part of the code dealing with the operating system interfaces.
4681		4963
4682	=item callback	4964	=item callback
4683		4965
4684	The address of a function that is called when some event has been	4966	The address of a function that is called when some event has been
4685	detected. Callbacks are being passed the event loop, the watcher that	4967	detected. Callbacks are being passed the event loop, the watcher that
4686	received the event, and the actual event bitset.	4968	received the event, and the actual event bitset.
4687		4969
4688	=item callback invocation	4970	=item callback/watcher invocation
4689		4971
4690	The act of calling the callback associated with a watcher.	4972	The act of calling the callback associated with a watcher.
4691		4973
4692	=item event	4974	=item event
4693		4975
…		…
4712	The model used to describe how an event loop handles and processes	4994	The model used to describe how an event loop handles and processes
4713	watchers and events.	4995	watchers and events.
4714		4996
4715	=item pending	4997	=item pending
4716		4998
4717	A watcher is pending as soon as the corresponding event has been detected,	4999	A watcher is pending as soon as the corresponding event has been
4718	and stops being pending as soon as the watcher will be invoked or its	5000	detected. See L<WATCHER STATES> for details.
4719	pending status is explicitly cleared by the application.
4720
4721	A watcher can be pending, but not active. Stopping a watcher also clears
4722	its pending status.
4723		5001
4724	=item real time	5002	=item real time
4725		5003
4726	The physical time that is observed. It is apparently strictly monotonic :)	5004	The physical time that is observed. It is apparently strictly monotonic :)
4727		5005
…		…
4734	=item watcher	5012	=item watcher
4735		5013
4736	A data structure that describes interest in certain events. Watchers need	5014	A data structure that describes interest in certain events. Watchers need
4737	to be started (attached to an event loop) before they can receive events.	5015	to be started (attached to an event loop) before they can receive events.
4738		5016
4739	=item watcher invocation
4740
4741	The act of calling the callback associated with a watcher.
4742
4743	=back	5017	=back
4744		5018
4745	=head1 AUTHOR	5019	=head1 AUTHOR
4746		5020
4747	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson.	5021	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael
		5022	Magnusson and Emanuele Giaquinta.
4748		5023

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