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Revision 1.292 by sf-exg, Mon Mar 22 09:57:01 2010 UTC vs.
Revision 1.346 by root, Wed Nov 10 14:50:54 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))
235		247
236	Sets the allocation function to use (the prototype is similar - the	248	Sets the allocation function to use (the prototype is similar - the
237	semantics are identical to the C<realloc> C89/SuS/POSIX function). It is	249	semantics are identical to the C<realloc> C89/SuS/POSIX function). It is
238	used to allocate and free memory (no surprises here). If it returns zero	250	used to allocate and free memory (no surprises here). If it returns zero
239	when memory needs to be allocated (C<size != 0>), the library might abort	251	when memory needs to be allocated (C<size != 0>), the library might abort
…		…
265	}	277	}
266		278
267	...	279	...
268	ev_set_allocator (persistent_realloc);	280	ev_set_allocator (persistent_realloc);
269		281
270	=item ev_set_syserr_cb (void (*cb)(const char *msg)); [NOT REENTRANT]	282	=item ev_set_syserr_cb (void (*cb)(const char *msg))
271		283
272	Set the callback function to call on a retryable system call error (such	284	Set the callback function to call on a retryable system call error (such
273	as failed select, poll, epoll_wait). The message is a printable string	285	as failed select, poll, epoll_wait). The message is a printable string
274	indicating the system call or subsystem causing the problem. If this	286	indicating the system call or subsystem causing the problem. If this
275	callback is set, then libev will expect it to remedy the situation, no	287	callback is set, then libev will expect it to remedy the situation, no
…		…
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	This function is thread-safe, and one common way to use libev with
		361	threads is indeed to create one loop per thread, and using the default
		362	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:
…		…
365	environment variable.	402	environment variable.
366		403
367	=item C<EVFLAG_NOINOTIFY>	404	=item C<EVFLAG_NOINOTIFY>
368		405
369	When this flag is specified, then libev will not attempt to use the	406	When this flag is specified, then libev will not attempt to use the
370	I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and	407	I<inotify> API for its C<ev_stat> watchers. Apart from debugging and
371	testing, this flag can be useful to conserve inotify file descriptors, as	408	testing, this flag can be useful to conserve inotify file descriptors, as
372	otherwise each loop using C<ev_stat> watchers consumes one inotify handle.	409	otherwise each loop using C<ev_stat> watchers consumes one inotify handle.
373		410
374	=item C<EVFLAG_SIGNALFD>	411	=item C<EVFLAG_SIGNALFD>
375		412
376	When this flag is specified, then libev will attempt to use the	413	When this flag is specified, then libev will attempt to use the
377	I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This API	414	I<signalfd> API for its C<ev_signal> (and C<ev_child>) watchers. This API
378	delivers signals synchronously, which makes it both faster and might make	415	delivers signals synchronously, which makes it both faster and might make
379	it possible to get the queued signal data. It can also simplify signal	416	it possible to get the queued signal data. It can also simplify signal
380	handling with threads, as long as you properly block signals in your	417	handling with threads, as long as you properly block signals in your
381	threads that are not interested in handling them.	418	threads that are not interested in handling them.
382		419
…		…
426	epoll scales either O(1) or O(active_fds).	463	epoll scales either O(1) or O(active_fds).
427		464
428	The epoll mechanism deserves honorable mention as the most misdesigned	465	The epoll mechanism deserves honorable mention as the most misdesigned
429	of the more advanced event mechanisms: mere annoyances include silently	466	of the more advanced event mechanisms: mere annoyances include silently
430	dropping file descriptors, requiring a system call per change per file	467	dropping file descriptors, requiring a system call per change per file
431	descriptor (and unnecessary guessing of parameters), problems with dup and	468	descriptor (and unnecessary guessing of parameters), problems with dup,
		469	returning before the timeout value, resulting in additional iterations
		470	(and only giving 5ms accuracy while select on the same platform gives
432	so on. The biggest issue is fork races, however - if a program forks then	471	0.1ms) and so on. The biggest issue is fork races, however - if a program
433	I<both> parent and child process have to recreate the epoll set, which can	472	forks then I<both> parent and child process have to recreate the epoll
434	take considerable time (one syscall per file descriptor) and is of course	473	set, which can take considerable time (one syscall per file descriptor)
435	hard to detect.	474	and is of course hard to detect.
436		475
437	Epoll is also notoriously buggy - embedding epoll fds I<should> work, but	476	Epoll is also notoriously buggy - embedding epoll fds I<should> work, but
438	of course I<doesn't>, and epoll just loves to report events for totally	477	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	478	I<different> file descriptors (even already closed ones, so one cannot
440	even remove them from the set) than registered in the set (especially	479	even remove them from the set) than registered in the set (especially
441	on SMP systems). Libev tries to counter these spurious notifications by	480	on SMP systems). Libev tries to counter these spurious notifications by
442	employing an additional generation counter and comparing that against the	481	employing an additional generation counter and comparing that against the
443	events to filter out spurious ones, recreating the set when required.	482	events to filter out spurious ones, recreating the set when required. Last
		483	not least, it also refuses to work with some file descriptors which work
		484	perfectly fine with C<select> (files, many character devices...).
		485
		486	Epoll is truly the train wreck analog among event poll mechanisms.
444		487
445	While stopping, setting and starting an I/O watcher in the same iteration	488	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	489	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	490	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	491	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,	589	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	590	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	591	here). If none are specified, all backends in C<ev_recommended_backends
549	()> will be tried.	592	()> will be tried.
550		593
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.	594	Example: Try to create a event loop that uses epoll and nothing else.
578		595
579	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	596	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
580	if (!epoller)	597	if (!epoller)
581	fatal ("no epoll found here, maybe it hides under your chair");	598	fatal ("no epoll found here, maybe it hides under your chair");
582		599
		600	Example: Use whatever libev has to offer, but make sure that kqueue is
		601	used if available.
		602
		603	struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE);
		604
583	=item ev_default_destroy ()	605	=item ev_loop_destroy (loop)
584		606
585	Destroys the default loop (frees all memory and kernel state etc.). None	607	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	608	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	609	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,	610	responsibility to either stop all watchers cleanly yourself I<before>
589	or cope with the fact afterwards (which is usually the easiest thing, you	611	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).	612	the easiest thing, you can just ignore the watchers and/or C<free ()> them
		613	for example).
591		614
592	Note that certain global state, such as signal state (and installed signal	615	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	616	handlers), will not be freed by this function, and related watchers (such
594	as signal and child watchers) would need to be stopped manually.	617	as signal and child watchers) would need to be stopped manually.
595		618
596	In general it is not advisable to call this function except in the	619	This function is normally used on loop objects allocated by
597	rare occasion where you really need to free e.g. the signal handling	620	C<ev_loop_new>, but it can also be used on the default loop returned by
		621	C<ev_default_loop>, in which case it is not thread-safe.
		622
		623	Note that it is not advisable to call this function on the default loop
		624	except in the rare occasion where you really need to free its resources.
598	pipe fds. If you need dynamically allocated loops it is better to use	625	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>.	626	and C<ev_loop_destroy>.
600		627
601	=item ev_loop_destroy (loop)	628	=item ev_loop_fork (loop)
602		629
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	630	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	631	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	632	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	633	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	634	child before resuming or calling C<ev_run>.
613	functions, and it will only take effect at the next C<ev_loop> iteration.
614		635
615	Again, you I<have> to call it on I<any> loop that you want to re-use after	636	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	637	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	638	because some kernel interfaces *cough* I<kqueue> *cough* do funny things
618	during fork.	639	during fork.
619		640
620	On the other hand, you only need to call this function in the child	641	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	642	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	643	you just fork+exec or create a new loop in the child, you don't have to
623	it at all.	644	call it at all (in fact, C<epoll> is so badly broken that it makes a
		645	difference, but libev will usually detect this case on its own and do a
		646	costly reset of the backend).
624		647
625	The function itself is quite fast and it's usually not a problem to call	648	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	649	it just in case after a fork.
627	quite nicely into a call to C<pthread_atfork>:
628		650
		651	Example: Automate calling C<ev_loop_fork> on the default loop when
		652	using pthreads.
		653
		654	static void
		655	post_fork_child (void)
		656	{
		657	ev_loop_fork (EV_DEFAULT);
		658	}
		659
		660	...
629	pthread_atfork (0, 0, ev_default_fork);	661	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		662
638	=item int ev_is_default_loop (loop)	663	=item int ev_is_default_loop (loop)
639		664
640	Returns true when the given loop is, in fact, the default loop, and false	665	Returns true when the given loop is, in fact, the default loop, and false
641	otherwise.	666	otherwise.
642		667
643	=item unsigned int ev_iteration (loop)	668	=item unsigned int ev_iteration (loop)
644		669
645	Returns the current iteration count for the loop, which is identical to	670	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	671	to the number of times libev did poll for new events. It starts at C<0>
647	happily wraps around with enough iterations.	672	and happily wraps around with enough iterations.
648		673
649	This value can sometimes be useful as a generation counter of sorts (it	674	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	675	"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	676	C<ev_prepare> and C<ev_check> calls - and is incremented between the
652	prepare and check phases.	677	prepare and check phases.
653		678
654	=item unsigned int ev_depth (loop)	679	=item unsigned int ev_depth (loop)
655		680
656	Returns the number of times C<ev_loop> was entered minus the number of	681	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.	682	times C<ev_run> was exited normally, in other words, the recursion depth.
658		683
659	Outside C<ev_loop>, this number is zero. In a callback, this number is	684	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),	685	C<1>, unless C<ev_run> was invoked recursively (or from another thread),
661	in which case it is higher.	686	in which case it is higher.
662		687
663	Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread	688	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	689	throwing an exception etc.), doesn't count as "exit" - consider this
665	ungentleman behaviour unless it's really convenient.	690	as a hint to avoid such ungentleman-like behaviour unless it's really
		691	convenient, in which case it is fully supported.
666		692
667	=item unsigned int ev_backend (loop)	693	=item unsigned int ev_backend (loop)
668		694
669	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	695	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
670	use.	696	use.
…		…
679		705
680	=item ev_now_update (loop)	706	=item ev_now_update (loop)
681		707
682	Establishes the current time by querying the kernel, updating the time	708	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	709	returned by C<ev_now ()> in the progress. This is a costly operation and
684	is usually done automatically within C<ev_loop ()>.	710	is usually done automatically within C<ev_run ()>.
685		711
686	This function is rarely useful, but when some event callback runs for a	712	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	713	very long time without entering the event loop, updating libev's idea of
688	the current time is a good idea.	714	the current time is a good idea.
689		715
…		…
691		717
692	=item ev_suspend (loop)	718	=item ev_suspend (loop)
693		719
694	=item ev_resume (loop)	720	=item ev_resume (loop)
695		721
696	These two functions suspend and resume a loop, for use when the loop is	722	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.	723	loop is not used for a while and timeouts should not be processed.
698		724
699	A typical use case would be an interactive program such as a game: When	725	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	726	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	727	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>	728	the program was suspended. This can be achieved by calling C<ev_suspend>
…		…
704	C<ev_resume> directly afterwards to resume timer processing.	730	C<ev_resume> directly afterwards to resume timer processing.
705		731
706	Effectively, all C<ev_timer> watchers will be delayed by the time spend	732	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	733	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	734	will be rescheduled (that is, they will lose any events that would have
709	occured while suspended).	735	occurred while suspended).
710		736
711	After calling C<ev_suspend> you B<must not> call I<any> function on the	737	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>	738	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>.	739	without a previous call to C<ev_suspend>.
714		740
715	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the	741	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the
716	event loop time (see C<ev_now_update>).	742	event loop time (see C<ev_now_update>).
717		743
718	=item ev_loop (loop, int flags)	744	=item ev_run (loop, int flags)
719		745
720	Finally, this is it, the event handler. This function usually is called	746	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	747	after you have initialised all your watchers and you want to start
722	handling events.	748	handling events. It will ask the operating system for any new events, call
		749	the watcher callbacks, an then repeat the whole process indefinitely: This
		750	is why event loops are called I<loops>.
723		751
724	If the flags argument is specified as C<0>, it will not return until	752	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.	753	until either no event watchers are active anymore or C<ev_break> was
		754	called.
726		755
727	Please note that an explicit C<ev_unloop> is usually better than	756	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	757	relying on all watchers to be stopped when deciding when a program has
729	finished (especially in interactive programs), but having a program	758	finished (especially in interactive programs), but having a program
730	that automatically loops as long as it has to and no longer by virtue	759	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	760	of relying on its watchers stopping correctly, that is truly a thing of
732	beauty.	761	beauty.
733		762
		763	This function is also I<mostly> exception-safe - you can break out of
		764	a C<ev_run> call by calling C<longjmp> in a callback, throwing a C++
		765	exception and so on. This does not decrement the C<ev_depth> value, nor
		766	will it clear any outstanding C<EVBREAK_ONE> breaks.
		767
734	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle	768	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	769	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	770	block your process in case there are no events and will return after one
737	the loop.	771	iteration of the loop. This is sometimes useful to poll and handle new
		772	events while doing lengthy calculations, to keep the program responsive.
738		773
739	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if	774	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	775	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	776	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	777	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	778	user-registered callback will be called), and will return after one
744	iteration of the loop.	779	iteration of the loop.
745		780
746	This is useful if you are waiting for some external event in conjunction	781	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	782	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	783	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.	784	usually a better approach for this kind of thing.
750		785
751	Here are the gory details of what C<ev_loop> does:	786	Here are the gory details of what C<ev_run> does:
752		787
		788	- Increment loop depth.
		789	- Reset the ev_break status.
753	- Before the first iteration, call any pending watchers.	790	- Before the first iteration, call any pending watchers.
		791	LOOP:
754	* If EVFLAG_FORKCHECK was used, check for a fork.	792	- If EVFLAG_FORKCHECK was used, check for a fork.
755	- If a fork was detected (by any means), queue and call all fork watchers.	793	- If a fork was detected (by any means), queue and call all fork watchers.
756	- Queue and call all prepare watchers.	794	- Queue and call all prepare watchers.
		795	- If ev_break was called, goto FINISH.
757	- If we have been forked, detach and recreate the kernel state	796	- If we have been forked, detach and recreate the kernel state
758	as to not disturb the other process.	797	as to not disturb the other process.
759	- Update the kernel state with all outstanding changes.	798	- Update the kernel state with all outstanding changes.
760	- Update the "event loop time" (ev_now ()).	799	- Update the "event loop time" (ev_now ()).
761	- Calculate for how long to sleep or block, if at all	800	- Calculate for how long to sleep or block, if at all
762	(active idle watchers, EVLOOP_NONBLOCK or not having	801	(active idle watchers, EVRUN_NOWAIT or not having
763	any active watchers at all will result in not sleeping).	802	any active watchers at all will result in not sleeping).
764	- Sleep if the I/O and timer collect interval say so.	803	- Sleep if the I/O and timer collect interval say so.
		804	- Increment loop iteration counter.
765	- Block the process, waiting for any events.	805	- Block the process, waiting for any events.
766	- Queue all outstanding I/O (fd) events.	806	- Queue all outstanding I/O (fd) events.
767	- Update the "event loop time" (ev_now ()), and do time jump adjustments.	807	- Update the "event loop time" (ev_now ()), and do time jump adjustments.
768	- Queue all expired timers.	808	- Queue all expired timers.
769	- Queue all expired periodics.	809	- Queue all expired periodics.
770	- Unless any events are pending now, queue all idle watchers.	810	- Queue all idle watchers with priority higher than that of pending events.
771	- Queue all check watchers.	811	- Queue all check watchers.
772	- Call all queued watchers in reverse order (i.e. check watchers first).	812	- 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	813	Signals and child watchers are implemented as I/O watchers, and will
774	be handled here by queueing them when their watcher gets executed.	814	be handled here by queueing them when their watcher gets executed.
775	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	815	- If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT
776	were used, or there are no active watchers, return, otherwise	816	were used, or there are no active watchers, goto FINISH, otherwise
777	continue with step *.	817	continue with step LOOP.
		818	FINISH:
		819	- Reset the ev_break status iff it was EVBREAK_ONE.
		820	- Decrement the loop depth.
		821	- Return.
778		822
779	Example: Queue some jobs and then loop until no events are outstanding	823	Example: Queue some jobs and then loop until no events are outstanding
780	anymore.	824	anymore.
781		825
782	... queue jobs here, make sure they register event watchers as long	826	... 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..)	827	... as they still have work to do (even an idle watcher will do..)
784	ev_loop (my_loop, 0);	828	ev_run (my_loop, 0);
785	... jobs done or somebody called unloop. yeah!	829	... jobs done or somebody called unloop. yeah!
786		830
787	=item ev_unloop (loop, how)	831	=item ev_break (loop, how)
788		832
789	Can be used to make a call to C<ev_loop> return early (but only after it	833	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	834	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	835	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.	836	C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return.
793		837
794	This "unloop state" will be cleared when entering C<ev_loop> again.	838	This "break state" will be cleared on the next call to C<ev_run>.
795		839
796	It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls.	840	It is safe to call C<ev_break> from outside any C<ev_run> calls, too, in
		841	which case it will have no effect.
797		842
798	=item ev_ref (loop)	843	=item ev_ref (loop)
799		844
800	=item ev_unref (loop)	845	=item ev_unref (loop)
801		846
802	Ref/unref can be used to add or remove a reference count on the event	847	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	848	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.	849	count is nonzero, C<ev_run> will not return on its own.
805		850
806	This is useful when you have a watcher that you never intend to	851	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	852	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>	853	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>
809	before stopping it.	854	before stopping it.
810		855
811	As an example, libev itself uses this for its internal signal pipe: It	856	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	857	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	858	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	859	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	860	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	861	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	862	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>	863	(e.g. non-repeating timers) in which case you have to C<ev_ref>
819	in the callback).	864	in the callback).
820		865
821	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	866	Example: Create a signal watcher, but keep it from keeping C<ev_run>
822	running when nothing else is active.	867	running when nothing else is active.
823		868
824	ev_signal exitsig;	869	ev_signal exitsig;
825	ev_signal_init (&exitsig, sig_cb, SIGINT);	870	ev_signal_init (&exitsig, sig_cb, SIGINT);
826	ev_signal_start (loop, &exitsig);	871	ev_signal_start (loop, &exitsig);
…		…
871	usually doesn't make much sense to set it to a lower value than C<0.01>,	916	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	917	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	918	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	919	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,	920	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).	921	then you can't do more than 100 transactions per second).
877		922
878	Setting the I<timeout collect interval> can improve the opportunity for	923	Setting the I<timeout collect interval> can improve the opportunity for
879	saving power, as the program will "bundle" timer callback invocations that	924	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	925	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	926	times the process sleeps and wakes up again. Another useful technique to
…		…
889	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);	934	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);
890		935
891	=item ev_invoke_pending (loop)	936	=item ev_invoke_pending (loop)
892		937
893	This call will simply invoke all pending watchers while resetting their	938	This call will simply invoke all pending watchers while resetting their
894	pending state. Normally, C<ev_loop> does this automatically when required,	939	pending state. Normally, C<ev_run> does this automatically when required,
895	but when overriding the invoke callback this call comes handy.	940	but when overriding the invoke callback this call comes handy. This
		941	function can be invoked from a watcher - this can be useful for example
		942	when you want to do some lengthy calculation and want to pass further
		943	event handling to another thread (you still have to make sure only one
		944	thread executes within C<ev_invoke_pending> or C<ev_run> of course).
896		945
897	=item int ev_pending_count (loop)	946	=item int ev_pending_count (loop)
898		947
899	Returns the number of pending watchers - zero indicates that no watchers	948	Returns the number of pending watchers - zero indicates that no watchers
900	are pending.	949	are pending.
901		950
902	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))	951	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))
903		952
904	This overrides the invoke pending functionality of the loop: Instead of	953	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	954	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	955	this callback instead. This is useful, for example, when you want to
907	invoke the actual watchers inside another context (another thread etc.).	956	invoke the actual watchers inside another context (another thread etc.).
908		957
909	If you want to reset the callback, use C<ev_invoke_pending> as new	958	If you want to reset the callback, use C<ev_invoke_pending> as new
910	callback.	959	callback.
…		…
913		962
914	Sometimes you want to share the same loop between multiple threads. This	963	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	964	can be done relatively simply by putting mutex_lock/unlock calls around
916	each call to a libev function.	965	each call to a libev function.
917		966
918	However, C<ev_loop> can run an indefinite time, so it is not feasible to	967	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	968	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>	969	loop via C<ev_break> and C<av_async_send>, another way is to set these
921	and I<acquire> callbacks on the loop.	970	I<release> and I<acquire> callbacks on the loop.
922		971
923	When set, then C<release> will be called just before the thread is	972	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	973	suspended waiting for new events, and C<acquire> is called just
925	afterwards.	974	afterwards.
926		975
…		…
929		978
930	While event loop modifications are allowed between invocations of	979	While event loop modifications are allowed between invocations of
931	C<release> and C<acquire> (that's their only purpose after all), no	980	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	981	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	982	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	983	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.	984	to take note of any changes you made.
936		985
937	In theory, threads executing C<ev_loop> will be async-cancel safe between	986	In theory, threads executing C<ev_run> will be async-cancel safe between
938	invocations of C<release> and C<acquire>.	987	invocations of C<release> and C<acquire>.
939		988
940	See also the locking example in the C<THREADS> section later in this	989	See also the locking example in the C<THREADS> section later in this
941	document.	990	document.
942		991
943	=item ev_set_userdata (loop, void *data)	992	=item ev_set_userdata (loop, void *data)
944		993
945	=item ev_userdata (loop)	994	=item void *ev_userdata (loop)
946		995
947	Set and retrieve a single C<void *> associated with a loop. When	996	Set and retrieve a single C<void *> associated with a loop. When
948	C<ev_set_userdata> has never been called, then C<ev_userdata> returns	997	C<ev_set_userdata> has never been called, then C<ev_userdata> returns
949	C<0.>	998	C<0>.
950		999
951	These two functions can be used to associate arbitrary data with a loop,	1000	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	1001	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	1002	C<acquire> callbacks described above, but of course can be (ab-)used for
954	any other purpose as well.	1003	any other purpose as well.
955		1004
956	=item ev_loop_verify (loop)	1005	=item ev_verify (loop)
957		1006
958	This function only does something when C<EV_VERIFY> support has been	1007	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	1008	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	1009	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	1010	is found to be inconsistent, it will print an error message to standard
…		…
972		1021
973	In the following description, uppercase C<TYPE> in names stands for the	1022	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	1023	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.	1024	watchers and C<ev_io_start> for I/O watchers.
976		1025
977	A watcher is a structure that you create and register to record your	1026	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	1027	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:	1028	to wait for STDIN to become readable, you would create an C<ev_io> watcher
		1029	for that:
980		1030
981	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)	1031	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)
982	{	1032	{
983	ev_io_stop (w);	1033	ev_io_stop (w);
984	ev_unloop (loop, EVUNLOOP_ALL);	1034	ev_break (loop, EVBREAK_ALL);
985	}	1035	}
986		1036
987	struct ev_loop *loop = ev_default_loop (0);	1037	struct ev_loop *loop = ev_default_loop (0);
988		1038
989	ev_io stdin_watcher;	1039	ev_io stdin_watcher;
990		1040
991	ev_init (&stdin_watcher, my_cb);	1041	ev_init (&stdin_watcher, my_cb);
992	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	1042	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
993	ev_io_start (loop, &stdin_watcher);	1043	ev_io_start (loop, &stdin_watcher);
994		1044
995	ev_loop (loop, 0);	1045	ev_run (loop, 0);
996		1046
997	As you can see, you are responsible for allocating the memory for your	1047	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	1048	watcher structures (and it is I<usually> a bad idea to do this on the
999	stack).	1049	stack).
1000		1050
1001	Each watcher has an associated watcher structure (called C<struct ev_TYPE>	1051	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).	1052	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).
1003		1053
1004	Each watcher structure must be initialised by a call to C<ev_init	1054	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	1055	*, 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	1056	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	1057	time the event loop detects that the file descriptor given is readable
1008	is readable and/or writable).	1058	and/or writable).
1009		1059
1010	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>	1060	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	1061	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<<	1062	is also a macro to combine initialisation and setting in one call: C<<
1013	ev_TYPE_init (watcher *, callback, ...) >>.	1063	ev_TYPE_init (watcher *, callback, ...) >>.
…		…
1064		1114
1065	=item C<EV_PREPARE>	1115	=item C<EV_PREPARE>
1066		1116
1067	=item C<EV_CHECK>	1117	=item C<EV_CHECK>
1068		1118
1069	All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts	1119	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	1120	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	1121	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	1122	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	1123	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	1124	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
1075	C<ev_loop> from blocking).	1125	C<ev_run> from blocking).
1076		1126
1077	=item C<EV_EMBED>	1127	=item C<EV_EMBED>
1078		1128
1079	The embedded event loop specified in the C<ev_embed> watcher needs attention.	1129	The embedded event loop specified in the C<ev_embed> watcher needs attention.
1080		1130
1081	=item C<EV_FORK>	1131	=item C<EV_FORK>
1082		1132
1083	The event loop has been resumed in the child process after fork (see	1133	The event loop has been resumed in the child process after fork (see
1084	C<ev_fork>).	1134	C<ev_fork>).
		1135
		1136	=item C<EV_CLEANUP>
		1137
		1138	The event loop is about to be destroyed (see C<ev_cleanup>).
1085		1139
1086	=item C<EV_ASYNC>	1140	=item C<EV_ASYNC>
1087		1141
1088	The given async watcher has been asynchronously notified (see C<ev_async>).	1142	The given async watcher has been asynchronously notified (see C<ev_async>).
1089		1143
…		…
1261		1315
1262	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related	1316	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related
1263	functions that do not need a watcher.	1317	functions that do not need a watcher.
1264		1318
1265	=back	1319	=back
1266
1267		1320
1268	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	1321	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
1269		1322
1270	Each watcher has, by default, a member C<void *data> that you can change	1323	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	1324	and read at any time: libev will completely ignore it. This can be used
…		…
1327	t2_cb (EV_P_ ev_timer *w, int revents)	1380	t2_cb (EV_P_ ev_timer *w, int revents)
1328	{	1381	{
1329	struct my_biggy big = (struct my_biggy *)	1382	struct my_biggy big = (struct my_biggy *)
1330	(((char *)w) - offsetof (struct my_biggy, t2));	1383	(((char *)w) - offsetof (struct my_biggy, t2));
1331	}	1384	}
		1385
		1386	=head2 WATCHER STATES
		1387
		1388	There are various watcher states mentioned throughout this manual -
		1389	active, pending and so on. In this section these states and the rules to
		1390	transition between them will be described in more detail - and while these
		1391	rules might look complicated, they usually do "the right thing".
		1392
		1393	=over 4
		1394
		1395	=item initialiased
		1396
		1397	Before a watcher can be registered with the event looop it has to be
		1398	initialised. This can be done with a call to C<ev_TYPE_init>, or calls to
		1399	C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function.
		1400
		1401	In this state it is simply some block of memory that is suitable for use
		1402	in an event loop. It can be moved around, freed, reused etc. at will.
		1403
		1404	=item started/running/active
		1405
		1406	Once a watcher has been started with a call to C<ev_TYPE_start> it becomes
		1407	property of the event loop, and is actively waiting for events. While in
		1408	this state it cannot be accessed (except in a few documented ways), moved,
		1409	freed or anything else - the only legal thing is to keep a pointer to it,
		1410	and call libev functions on it that are documented to work on active watchers.
		1411
		1412	=item pending
		1413
		1414	If a watcher is active and libev determines that an event it is interested
		1415	in has occurred (such as a timer expiring), it will become pending. It will
		1416	stay in this pending state until either it is stopped or its callback is
		1417	about to be invoked, so it is not normally pending inside the watcher
		1418	callback.
		1419
		1420	The watcher might or might not be active while it is pending (for example,
		1421	an expired non-repeating timer can be pending but no longer active). If it
		1422	is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>),
		1423	but it is still property of the event loop at this time, so cannot be
		1424	moved, freed or reused. And if it is active the rules described in the
		1425	previous item still apply.
		1426
		1427	It is also possible to feed an event on a watcher that is not active (e.g.
		1428	via C<ev_feed_event>), in which case it becomes pending without being
		1429	active.
		1430
		1431	=item stopped
		1432
		1433	A watcher can be stopped implicitly by libev (in which case it might still
		1434	be pending), or explicitly by calling its C<ev_TYPE_stop> function. The
		1435	latter will clear any pending state the watcher might be in, regardless
		1436	of whether it was active or not, so stopping a watcher explicitly before
		1437	freeing it is often a good idea.
		1438
		1439	While stopped (and not pending) the watcher is essentially in the
		1440	initialised state, that is it can be reused, moved, modified in any way
		1441	you wish.
		1442
		1443	=back
1332		1444
1333	=head2 WATCHER PRIORITY MODELS	1445	=head2 WATCHER PRIORITY MODELS
1334		1446
1335	Many event loops support I<watcher priorities>, which are usually small	1447	Many event loops support I<watcher priorities>, which are usually small
1336	integers that influence the ordering of event callback invocation	1448	integers that influence the ordering of event callback invocation
…		…
1379		1491
1380	For example, to emulate how many other event libraries handle priorities,	1492	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	1493	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	1494	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	1495	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	1496	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	1497	the lock-out case is known to be rare (which in turn is rare :), this is
1386	workable.	1498	workable.
1387		1499
1388	Usually, however, the lock-out model implemented that way will perform	1500	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,	1501	miserably under the type of load it was designed to handle. In that case,
…		…
1403	{	1515	{
1404	// stop the I/O watcher, we received the event, but	1516	// stop the I/O watcher, we received the event, but
1405	// are not yet ready to handle it.	1517	// are not yet ready to handle it.
1406	ev_io_stop (EV_A_ w);	1518	ev_io_stop (EV_A_ w);
1407		1519
1408	// start the idle watcher to ahndle the actual event.	1520	// start the idle watcher to handle the actual event.
1409	// it will not be executed as long as other watchers	1521	// it will not be executed as long as other watchers
1410	// with the default priority are receiving events.	1522	// with the default priority are receiving events.
1411	ev_idle_start (EV_A_ &idle);	1523	ev_idle_start (EV_A_ &idle);
1412	}	1524	}
1413		1525
…		…
1467		1579
1468	If you cannot use non-blocking mode, then force the use of a	1580	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	1581	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	1582	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file
1471	descriptors for which non-blocking operation makes no sense (such as	1583	descriptors for which non-blocking operation makes no sense (such as
1472	files) - libev doesn't guarentee any specific behaviour in that case.	1584	files) - libev doesn't guarantee any specific behaviour in that case.
1473		1585
1474	Another thing you have to watch out for is that it is quite easy to	1586	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	1587	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	1588	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	1589	because there is no data. Not only are some backends known to create a
…		…
1621	...	1733	...
1622	struct ev_loop *loop = ev_default_init (0);	1734	struct ev_loop *loop = ev_default_init (0);
1623	ev_io stdin_readable;	1735	ev_io stdin_readable;
1624	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1736	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1625	ev_io_start (loop, &stdin_readable);	1737	ev_io_start (loop, &stdin_readable);
1626	ev_loop (loop, 0);	1738	ev_run (loop, 0);
1627		1739
1628		1740
1629	=head2 C<ev_timer> - relative and optionally repeating timeouts	1741	=head2 C<ev_timer> - relative and optionally repeating timeouts
1630		1742
1631	Timer watchers are simple relative timers that generate an event after a	1743	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	1752	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	1753	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	1754	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	1755	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	1756	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).	1757	no longer true when a callback calls C<ev_run> recursively).
1646		1758
1647	=head3 Be smart about timeouts	1759	=head3 Be smart about timeouts
1648		1760
1649	Many real-world problems involve some kind of timeout, usually for error	1761	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,	1762	recovery. A typical example is an HTTP request - if the other side hangs,
…		…
1736	ev_tstamp timeout = last_activity + 60.;	1848	ev_tstamp timeout = last_activity + 60.;
1737		1849
1738	// if last_activity + 60. is older than now, we did time out	1850	// if last_activity + 60. is older than now, we did time out
1739	if (timeout < now)	1851	if (timeout < now)
1740	{	1852	{
1741	// timeout occured, take action	1853	// timeout occurred, take action
1742	}	1854	}
1743	else	1855	else
1744	{	1856	{
1745	// callback was invoked, but there was some activity, re-arm	1857	// callback was invoked, but there was some activity, re-arm
1746	// the watcher to fire in last_activity + 60, which is	1858	// the watcher to fire in last_activity + 60, which is
…		…
1773	callback (loop, timer, EV_TIMER);	1885	callback (loop, timer, EV_TIMER);
1774		1886
1775	And when there is some activity, simply store the current time in	1887	And when there is some activity, simply store the current time in
1776	C<last_activity>, no libev calls at all:	1888	C<last_activity>, no libev calls at all:
1777		1889
1778	last_actiivty = ev_now (loop);	1890	last_activity = ev_now (loop);
1779		1891
1780	This technique is slightly more complex, but in most cases where the	1892	This technique is slightly more complex, but in most cases where the
1781	time-out is unlikely to be triggered, much more efficient.	1893	time-out is unlikely to be triggered, much more efficient.
1782		1894
1783	Changing the timeout is trivial as well (if it isn't hard-coded in the	1895	Changing the timeout is trivial as well (if it isn't hard-coded in the
…		…
1821		1933
1822	=head3 The special problem of time updates	1934	=head3 The special problem of time updates
1823		1935
1824	Establishing the current time is a costly operation (it usually takes at	1936	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	1937	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	1938	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	1939	growing difference between C<ev_now ()> and C<ev_time ()> when handling
1828	lots of events in one iteration.	1940	lots of events in one iteration.
1829		1941
1830	The relative timeouts are calculated relative to the C<ev_now ()>	1942	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	1943	time. This is usually the right thing as this timestamp refers to the time
…		…
1948	}	2060	}
1949		2061
1950	ev_timer mytimer;	2062	ev_timer mytimer;
1951	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	2063	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1952	ev_timer_again (&mytimer); /* start timer */	2064	ev_timer_again (&mytimer); /* start timer */
1953	ev_loop (loop, 0);	2065	ev_run (loop, 0);
1954		2066
1955	// and in some piece of code that gets executed on any "activity":	2067	// and in some piece of code that gets executed on any "activity":
1956	// reset the timeout to start ticking again at 10 seconds	2068	// reset the timeout to start ticking again at 10 seconds
1957	ev_timer_again (&mytimer);	2069	ev_timer_again (&mytimer);
1958		2070
…		…
1984		2096
1985	As with timers, the callback is guaranteed to be invoked only when the	2097	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	2098	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	2099	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	2100	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).	2101	(but this is no longer true when a callback calls C<ev_run> recursively).
1990		2102
1991	=head3 Watcher-Specific Functions and Data Members	2103	=head3 Watcher-Specific Functions and Data Members
1992		2104
1993	=over 4	2105	=over 4
1994		2106
…		…
2122	Example: Call a callback every hour, or, more precisely, whenever the	2234	Example: Call a callback every hour, or, more precisely, whenever the
2123	system time is divisible by 3600. The callback invocation times have	2235	system time is divisible by 3600. The callback invocation times have
2124	potentially a lot of jitter, but good long-term stability.	2236	potentially a lot of jitter, but good long-term stability.
2125		2237
2126	static void	2238	static void
2127	clock_cb (struct ev_loop *loop, ev_io *w, int revents)	2239	clock_cb (struct ev_loop *loop, ev_periodic *w, int revents)
2128	{	2240	{
2129	... its now a full hour (UTC, or TAI or whatever your clock follows)	2241	... its now a full hour (UTC, or TAI or whatever your clock follows)
2130	}	2242	}
2131		2243
2132	ev_periodic hourly_tick;	2244	ev_periodic hourly_tick;
…		…
2155		2267
2156	=head2 C<ev_signal> - signal me when a signal gets signalled!	2268	=head2 C<ev_signal> - signal me when a signal gets signalled!
2157		2269
2158	Signal watchers will trigger an event when the process receives a specific	2270	Signal watchers will trigger an event when the process receives a specific
2159	signal one or more times. Even though signals are very asynchronous, libev	2271	signal one or more times. Even though signals are very asynchronous, libev
2160	will try it's best to deliver signals synchronously, i.e. as part of the	2272	will try its best to deliver signals synchronously, i.e. as part of the
2161	normal event processing, like any other event.	2273	normal event processing, like any other event.
2162		2274
2163	If you want signals to be delivered truly asynchronously, just use	2275	If you want signals to be delivered truly asynchronously, just use
2164	C<sigaction> as you would do without libev and forget about sharing	2276	C<sigaction> as you would do without libev and forget about sharing
2165	the signal. You can even use C<ev_async> from a signal handler to	2277	the signal. You can even use C<ev_async> from a signal handler to
…		…
2232	Example: Try to exit cleanly on SIGINT.	2344	Example: Try to exit cleanly on SIGINT.
2233		2345
2234	static void	2346	static void
2235	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)	2347	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)
2236	{	2348	{
2237	ev_unloop (loop, EVUNLOOP_ALL);	2349	ev_break (loop, EVBREAK_ALL);
2238	}	2350	}
2239		2351
2240	ev_signal signal_watcher;	2352	ev_signal signal_watcher;
2241	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	2353	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
2242	ev_signal_start (loop, &signal_watcher);	2354	ev_signal_start (loop, &signal_watcher);
…		…
2628		2740
2629	Prepare and check watchers are usually (but not always) used in pairs:	2741	Prepare and check watchers are usually (but not always) used in pairs:
2630	prepare watchers get invoked before the process blocks and check watchers	2742	prepare watchers get invoked before the process blocks and check watchers
2631	afterwards.	2743	afterwards.
2632		2744
2633	You I<must not> call C<ev_loop> or similar functions that enter	2745	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>	2746	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	2747	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	2748	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,	2749	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	2750	C<ev_check> so if you have one watcher of each kind they will always be
…		…
2806		2918
2807	if (timeout >= 0)	2919	if (timeout >= 0)
2808	// create/start timer	2920	// create/start timer
2809		2921
2810	// poll	2922	// poll
2811	ev_loop (EV_A_ 0);	2923	ev_run (EV_A_ 0);
2812		2924
2813	// stop timer again	2925	// stop timer again
2814	if (timeout >= 0)	2926	if (timeout >= 0)
2815	ev_timer_stop (EV_A_ &to);	2927	ev_timer_stop (EV_A_ &to);
2816		2928
…		…
2894	if you do not want that, you need to temporarily stop the embed watcher).	3006	if you do not want that, you need to temporarily stop the embed watcher).
2895		3007
2896	=item ev_embed_sweep (loop, ev_embed *)	3008	=item ev_embed_sweep (loop, ev_embed *)
2897		3009
2898	Make a single, non-blocking sweep over the embedded loop. This works	3010	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	3011	similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most
2900	appropriate way for embedded loops.	3012	appropriate way for embedded loops.
2901		3013
2902	=item struct ev_loop *other [read-only]	3014	=item struct ev_loop *other [read-only]
2903		3015
2904	The embedded event loop.	3016	The embedded event loop.
…		…
2964	C<ev_default_fork> cheats and calls it in the wrong process, the fork	3076	C<ev_default_fork> cheats and calls it in the wrong process, the fork
2965	handlers will be invoked, too, of course.	3077	handlers will be invoked, too, of course.
2966		3078
2967	=head3 The special problem of life after fork - how is it possible?	3079	=head3 The special problem of life after fork - how is it possible?
2968		3080
2969	Most uses of C<fork()> consist of forking, then some simple calls to ste	3081	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	3082	up/change the process environment, followed by a call to C<exec()>. This
2971	sequence should be handled by libev without any problems.	3083	sequence should be handled by libev without any problems.
2972		3084
2973	This changes when the application actually wants to do event handling	3085	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	3086	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	3102	disadvantage of having to use multiple event loops (which do not support
2991	signal watchers).	3103	signal watchers).
2992		3104
2993	When this is not possible, or you want to use the default loop for	3105	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	3106	other reasons, then in the process that wants to start "fresh", call
2995	C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying	3107	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	3108	Destroying the default loop will "orphan" (not stop) all registered
2997	have to be careful not to execute code that modifies those watchers. Note	3109	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.	3110	those watchers. Note also that in that case, you have to re-register any
		3111	signal watchers.
2999		3112
3000	=head3 Watcher-Specific Functions and Data Members	3113	=head3 Watcher-Specific Functions and Data Members
3001		3114
3002	=over 4	3115	=over 4
3003		3116
3004	=item ev_fork_init (ev_signal *, callback)	3117	=item ev_fork_init (ev_fork *, callback)
3005		3118
3006	Initialises and configures the fork watcher - it has no parameters of any	3119	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,	3120	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
3008	believe me.	3121	really.
3009		3122
3010	=back	3123	=back
3011		3124
3012		3125
		3126	=head2 C<ev_cleanup> - even the best things end
		3127
		3128	Cleanup watchers are called just before the event loop is being destroyed
		3129	by a call to C<ev_loop_destroy>.
		3130
		3131	While there is no guarantee that the event loop gets destroyed, cleanup
		3132	watchers provide a convenient method to install cleanup hooks for your
		3133	program, worker threads and so on - you just to make sure to destroy the
		3134	loop when you want them to be invoked.
		3135
		3136	Cleanup watchers are invoked in the same way as any other watcher. Unlike
		3137	all other watchers, they do not keep a reference to the event loop (which
		3138	makes a lot of sense if you think about it). Like all other watchers, you
		3139	can call libev functions in the callback, except C<ev_cleanup_start>.
		3140
		3141	=head3 Watcher-Specific Functions and Data Members
		3142
		3143	=over 4
		3144
		3145	=item ev_cleanup_init (ev_cleanup *, callback)
		3146
		3147	Initialises and configures the cleanup watcher - it has no parameters of
		3148	any kind. There is a C<ev_cleanup_set> macro, but using it is utterly
		3149	pointless, I assure you.
		3150
		3151	=back
		3152
		3153	Example: Register an atexit handler to destroy the default loop, so any
		3154	cleanup functions are called.
		3155
		3156	static void
		3157	program_exits (void)
		3158	{
		3159	ev_loop_destroy (EV_DEFAULT_UC);
		3160	}
		3161
		3162	...
		3163	atexit (program_exits);
		3164
		3165
3013	=head2 C<ev_async> - how to wake up another event loop	3166	=head2 C<ev_async> - how to wake up an event loop
3014		3167
3015	In general, you cannot use an C<ev_loop> from multiple threads or other	3168	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	3169	asynchronous sources such as signal handlers (as opposed to multiple event
3017	loops - those are of course safe to use in different threads).	3170	loops - those are of course safe to use in different threads).
3018		3171
3019	Sometimes, however, you need to wake up another event loop you do not	3172	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	3173	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	3174	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	3175	it by calling C<ev_async_send>, which is thread- and signal safe.
3023	safe.
3024		3176
3025	This functionality is very similar to C<ev_signal> watchers, as signals,	3177	This functionality is very similar to C<ev_signal> watchers, as signals,
3026	too, are asynchronous in nature, and signals, too, will be compressed	3178	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	3179	(i.e. the number of callback invocations may be less than the number of
3028	C<ev_async_sent> calls).	3180	C<ev_async_sent> calls).
…		…
3215	loop!).	3367	loop!).
3216		3368
3217	=back	3369	=back
3218		3370
3219		3371
		3372	=head1 COMMON OR USEFUL IDIOMS (OR BOTH)
		3373
		3374	This section explains some common idioms that are not immediately
		3375	obvious. Note that examples are sprinkled over the whole manual, and this
		3376	section only contains stuff that wouldn't fit anywhere else.
		3377
		3378	=over 4
		3379
		3380	=item Model/nested event loop invocations and exit conditions.
		3381
		3382	Often (especially in GUI toolkits) there are places where you have
		3383	I<modal> interaction, which is most easily implemented by recursively
		3384	invoking C<ev_run>.
		3385
		3386	This brings the problem of exiting - a callback might want to finish the
		3387	main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but
		3388	a modal "Are you sure?" dialog is still waiting), or just the nested one
		3389	and not the main one (e.g. user clocked "Ok" in a modal dialog), or some
		3390	other combination: In these cases, C<ev_break> will not work alone.
		3391
		3392	The solution is to maintain "break this loop" variable for each C<ev_run>
		3393	invocation, and use a loop around C<ev_run> until the condition is
		3394	triggered, using C<EVRUN_ONCE>:
		3395
		3396	// main loop
		3397	int exit_main_loop = 0;
		3398
		3399	while (!exit_main_loop)
		3400	ev_run (EV_DEFAULT_ EVRUN_ONCE);
		3401
		3402	// in a model watcher
		3403	int exit_nested_loop = 0;
		3404
		3405	while (!exit_nested_loop)
		3406	ev_run (EV_A_ EVRUN_ONCE);
		3407
		3408	To exit from any of these loops, just set the corresponding exit variable:
		3409
		3410	// exit modal loop
		3411	exit_nested_loop = 1;
		3412
		3413	// exit main program, after modal loop is finished
		3414	exit_main_loop = 1;
		3415
		3416	// exit both
		3417	exit_main_loop = exit_nested_loop = 1;
		3418
		3419	=back
		3420
		3421
3220	=head1 LIBEVENT EMULATION	3422	=head1 LIBEVENT EMULATION
3221		3423
3222	Libev offers a compatibility emulation layer for libevent. It cannot	3424	Libev offers a compatibility emulation layer for libevent. It cannot
3223	emulate the internals of libevent, so here are some usage hints:	3425	emulate the internals of libevent, so here are some usage hints:
3224		3426
3225	=over 4	3427	=over 4
		3428
		3429	=item * Only the libevent-1.4.1-beta API is being emulated.
		3430
		3431	This was the newest libevent version available when libev was implemented,
		3432	and is still mostly uncanged in 2010.
3226		3433
3227	=item * Use it by including <event.h>, as usual.	3434	=item * Use it by including <event.h>, as usual.
3228		3435
3229	=item * The following members are fully supported: ev_base, ev_callback,	3436	=item * The following members are fully supported: ev_base, ev_callback,
3230	ev_arg, ev_fd, ev_res, ev_events.	3437	ev_arg, ev_fd, ev_res, ev_events.
…		…
3236	=item * Priorities are not currently supported. Initialising priorities	3443	=item * Priorities are not currently supported. Initialising priorities
3237	will fail and all watchers will have the same priority, even though there	3444	will fail and all watchers will have the same priority, even though there
3238	is an ev_pri field.	3445	is an ev_pri field.
3239		3446
3240	=item * In libevent, the last base created gets the signals, in libev, the	3447	=item * In libevent, the last base created gets the signals, in libev, the
3241	first base created (== the default loop) gets the signals.	3448	base that registered the signal gets the signals.
3242		3449
3243	=item * Other members are not supported.	3450	=item * Other members are not supported.
3244		3451
3245	=item * The libev emulation is I<not> ABI compatible to libevent, you need	3452	=item * The libev emulation is I<not> ABI compatible to libevent, you need
3246	to use the libev header file and library.	3453	to use the libev header file and library.
…		…
3265	Care has been taken to keep the overhead low. The only data member the C++	3472	Care has been taken to keep the overhead low. The only data member the C++
3266	classes add (compared to plain C-style watchers) is the event loop pointer	3473	classes add (compared to plain C-style watchers) is the event loop pointer
3267	that the watcher is associated with (or no additional members at all if	3474	that the watcher is associated with (or no additional members at all if
3268	you disable C<EV_MULTIPLICITY> when embedding libev).	3475	you disable C<EV_MULTIPLICITY> when embedding libev).
3269		3476
3270	Currently, functions, and static and non-static member functions can be	3477	Currently, functions, static and non-static member functions and classes
3271	used as callbacks. Other types should be easy to add as long as they only	3478	with C<operator ()> can be used as callbacks. Other types should be easy
3272	need one additional pointer for context. If you need support for other	3479	to add as long as they only need one additional pointer for context. If
3273	types of functors please contact the author (preferably after implementing	3480	you need support for other types of functors please contact the author
3274	it).	3481	(preferably after implementing it).
3275		3482
3276	Here is a list of things available in the C<ev> namespace:	3483	Here is a list of things available in the C<ev> namespace:
3277		3484
3278	=over 4	3485	=over 4
3279		3486
…		…
3340	myclass obj;	3547	myclass obj;
3341	ev::io iow;	3548	ev::io iow;
3342	iow.set <myclass, &myclass::io_cb> (&obj);	3549	iow.set <myclass, &myclass::io_cb> (&obj);
3343		3550
3344	=item w->set (object *)	3551	=item w->set (object *)
3345
3346	This is an B<experimental> feature that might go away in a future version.
3347		3552
3348	This is a variation of a method callback - leaving out the method to call	3553	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	3554	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	3555	functor objects without having to manually specify the C<operator ()> all
3351	the time. Incidentally, you can then also leave out the template argument	3556	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	3596	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).	3597	do this when the watcher is inactive (and not pending either).
3393		3598
3394	=item w->set ([arguments])	3599	=item w->set ([arguments])
3395		3600
3396	Basically the same as C<ev_TYPE_set>, with the same arguments. Must be	3601	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	3602	method or a suitable start method must be called at least once. Unlike the
3398	automatically stopped and restarted when reconfiguring it with this	3603	C counterpart, an active watcher gets automatically stopped and restarted
3399	method.	3604	when reconfiguring it with this method.
3400		3605
3401	=item w->start ()	3606	=item w->start ()
3402		3607
3403	Starts the watcher. Note that there is no C<loop> argument, as the	3608	Starts the watcher. Note that there is no C<loop> argument, as the
3404	constructor already stores the event loop.	3609	constructor already stores the event loop.
3405		3610
		3611	=item w->start ([arguments])
		3612
		3613	Instead of calling C<set> and C<start> methods separately, it is often
		3614	convenient to wrap them in one call. Uses the same type of arguments as
		3615	the configure C<set> method of the watcher.
		3616
3406	=item w->stop ()	3617	=item w->stop ()
3407		3618
3408	Stops the watcher if it is active. Again, no C<loop> argument.	3619	Stops the watcher if it is active. Again, no C<loop> argument.
3409		3620
3410	=item w->again () (C<ev::timer>, C<ev::periodic> only)	3621	=item w->again () (C<ev::timer>, C<ev::periodic> only)
…		…
3422		3633
3423	=back	3634	=back
3424		3635
3425	=back	3636	=back
3426		3637
3427	Example: Define a class with an IO and idle watcher, start one of them in	3638	Example: Define a class with two I/O and idle watchers, start the I/O
3428	the constructor.	3639	watchers in the constructor.
3429		3640
3430	class myclass	3641	class myclass
3431	{	3642	{
3432	ev::io io ; void io_cb (ev::io &w, int revents);	3643	ev::io io ; void io_cb (ev::io &w, int revents);
		3644	ev::io2 io2 ; void io2_cb (ev::io &w, int revents);
3433	ev::idle idle; void idle_cb (ev::idle &w, int revents);	3645	ev::idle idle; void idle_cb (ev::idle &w, int revents);
3434		3646
3435	myclass (int fd)	3647	myclass (int fd)
3436	{	3648	{
3437	io .set <myclass, &myclass::io_cb > (this);	3649	io .set <myclass, &myclass::io_cb > (this);
		3650	io2 .set <myclass, &myclass::io2_cb > (this);
3438	idle.set <myclass, &myclass::idle_cb> (this);	3651	idle.set <myclass, &myclass::idle_cb> (this);
3439		3652
3440	io.start (fd, ev::READ);	3653	io.set (fd, ev::WRITE); // configure the watcher
		3654	io.start (); // start it whenever convenient
		3655
		3656	io2.start (fd, ev::READ); // set + start in one call
3441	}	3657	}
3442	};	3658	};
3443		3659
3444		3660
3445	=head1 OTHER LANGUAGE BINDINGS	3661	=head1 OTHER LANGUAGE BINDINGS
…		…
3519	loop argument"). The C<EV_A> form is used when this is the sole argument,	3735	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:	3736	C<EV_A_> is used when other arguments are following. Example:
3521		3737
3522	ev_unref (EV_A);	3738	ev_unref (EV_A);
3523	ev_timer_add (EV_A_ watcher);	3739	ev_timer_add (EV_A_ watcher);
3524	ev_loop (EV_A_ 0);	3740	ev_run (EV_A_ 0);
3525		3741
3526	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	3742	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
3527	which is often provided by the following macro.	3743	which is often provided by the following macro.
3528		3744
3529	=item C<EV_P>, C<EV_P_>	3745	=item C<EV_P>, C<EV_P_>
…		…
3569	}	3785	}
3570		3786
3571	ev_check check;	3787	ev_check check;
3572	ev_check_init (&check, check_cb);	3788	ev_check_init (&check, check_cb);
3573	ev_check_start (EV_DEFAULT_ &check);	3789	ev_check_start (EV_DEFAULT_ &check);
3574	ev_loop (EV_DEFAULT_ 0);	3790	ev_run (EV_DEFAULT_ 0);
3575		3791
3576	=head1 EMBEDDING	3792	=head1 EMBEDDING
3577		3793
3578	Libev can (and often is) directly embedded into host	3794	Libev can (and often is) directly embedded into host
3579	applications. Examples of applications that embed it include the Deliantra	3795	applications. Examples of applications that embed it include the Deliantra
…		…
3670	to a compiled library. All other symbols change the ABI, which means all	3886	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	3887	users of libev and the libev code itself must be compiled with compatible
3672	settings.	3888	settings.
3673		3889
3674	=over 4	3890	=over 4
		3891
		3892	=item EV_COMPAT3 (h)
		3893
		3894	Backwards compatibility is a major concern for libev. This is why this
		3895	release of libev comes with wrappers for the functions and symbols that
		3896	have been renamed between libev version 3 and 4.
		3897
		3898	You can disable these wrappers (to test compatibility with future
		3899	versions) by defining C<EV_COMPAT3> to C<0> when compiling your
		3900	sources. This has the additional advantage that you can drop the C<struct>
		3901	from C<struct ev_loop> declarations, as libev will provide an C<ev_loop>
		3902	typedef in that case.
		3903
		3904	In some future version, the default for C<EV_COMPAT3> will become C<0>,
		3905	and in some even more future version the compatibility code will be
		3906	removed completely.
3675		3907
3676	=item EV_STANDALONE (h)	3908	=item EV_STANDALONE (h)
3677		3909
3678	Must always be C<1> if you do not use autoconf configuration, which	3910	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	3911	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,	4118	EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE,
3887	EV_ASYNC_ENABLE, EV_CHILD_ENABLE.	4119	EV_ASYNC_ENABLE, EV_CHILD_ENABLE.
3888		4120
3889	If undefined or defined to be C<1> (and the platform supports it), then	4121	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	4122	the respective watcher type is supported. If defined to be C<0>, then it
3891	is not. Disabling watcher types mainly saves codesize.	4123	is not. Disabling watcher types mainly saves code size.
3892		4124
3893	=item EV_FEATURES	4125	=item EV_FEATURES
3894		4126
3895	If you need to shave off some kilobytes of code at the expense of some	4127	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	4128	speed (but with the full API), you can define this symbol to request
…		…
3916		4148
3917	=item C<1> - faster/larger code	4149	=item C<1> - faster/larger code
3918		4150
3919	Use larger code to speed up some operations.	4151	Use larger code to speed up some operations.
3920		4152
3921	Currently this is used to override some inlining decisions (enlarging the roughly	4153	Currently this is used to override some inlining decisions (enlarging the
3922	30% code size on amd64.	4154	code size by roughly 30% on amd64).
3923		4155
3924	When optimising for size, use of compiler flags such as C<-Os> with	4156	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	4157	gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of
3926	assertions.	4158	assertions.
3927		4159
3928	=item C<2> - faster/larger data structures	4160	=item C<2> - faster/larger data structures
3929		4161
3930	Replaces the small 2-heap for timer management by a faster 4-heap, larger	4162	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	4163	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	4164	and can additionally have an effect on the size of data structures at
3933	runtime.	4165	runtime.
3934		4166
3935	=item C<4> - full API configuration	4167	=item C<4> - full API configuration
3936		4168
…		…
3973	I/O watcher then might come out at only 5Kb.	4205	I/O watcher then might come out at only 5Kb.
3974		4206
3975	=item EV_AVOID_STDIO	4207	=item EV_AVOID_STDIO
3976		4208
3977	If this is set to C<1> at compiletime, then libev will avoid using stdio	4209	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	4210	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	4211	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	4212	libc allows it, this avoids linking in the stdio library which is quite
3981	big.	4213	big.
3982		4214
3983	Note that error messages might become less precise when this option is	4215	Note that error messages might become less precise when this option is
…		…
3987		4219
3988	The highest supported signal number, +1 (or, the number of	4220	The highest supported signal number, +1 (or, the number of
3989	signals): Normally, libev tries to deduce the maximum number of signals	4221	signals): Normally, libev tries to deduce the maximum number of signals
3990	automatically, but sometimes this fails, in which case it can be	4222	automatically, but sometimes this fails, in which case it can be
3991	specified. Also, using a lower number than detected (C<32> should be	4223	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	4224	good for about any system in existence) can save some memory, as libev
3993	statically allocates some 12-24 bytes per signal number.	4225	statically allocates some 12-24 bytes per signal number.
3994		4226
3995	=item EV_PID_HASHSIZE	4227	=item EV_PID_HASHSIZE
3996		4228
3997	C<ev_child> watchers use a small hash table to distribute workload by	4229	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	4261	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
4030	will be C<0>.	4262	will be C<0>.
4031		4263
4032	=item EV_VERIFY	4264	=item EV_VERIFY
4033		4265
4034	Controls how much internal verification (see C<ev_loop_verify ()>) will	4266	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	4267	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	4268	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	4269	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	4270	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	4271	verification code will be called very frequently, which will slow down
…		…
4043	will be C<0>.	4275	will be C<0>.
4044		4276
4045	=item EV_COMMON	4277	=item EV_COMMON
4046		4278
4047	By default, all watchers have a C<void *data> member. By redefining	4279	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	4280	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,	4281	members. You have to define it each time you include one of the files,
4050	though, and it must be identical each time.	4282	though, and it must be identical each time.
4051		4283
4052	For example, the perl EV module uses something like this:	4284	For example, the perl EV module uses something like this:
4053		4285
…		…
4254	userdata *u = ev_userdata (EV_A);	4486	userdata *u = ev_userdata (EV_A);
4255	pthread_mutex_lock (&u->lock);	4487	pthread_mutex_lock (&u->lock);
4256	}	4488	}
4257		4489
4258	The event loop thread first acquires the mutex, and then jumps straight	4490	The event loop thread first acquires the mutex, and then jumps straight
4259	into C<ev_loop>:	4491	into C<ev_run>:
4260		4492
4261	void *	4493	void *
4262	l_run (void *thr_arg)	4494	l_run (void *thr_arg)
4263	{	4495	{
4264	struct ev_loop *loop = (struct ev_loop *)thr_arg;	4496	struct ev_loop *loop = (struct ev_loop *)thr_arg;
4265		4497
4266	l_acquire (EV_A);	4498	l_acquire (EV_A);
4267	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);	4499	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
4268	ev_loop (EV_A_ 0);	4500	ev_run (EV_A_ 0);
4269	l_release (EV_A);	4501	l_release (EV_A);
4270		4502
4271	return 0;	4503	return 0;
4272	}	4504	}
4273		4505
…		…
4325		4557
4326	=head3 COROUTINES	4558	=head3 COROUTINES
4327		4559
4328	Libev is very accommodating to coroutines ("cooperative threads"):	4560	Libev is very accommodating to coroutines ("cooperative threads"):
4329	libev fully supports nesting calls to its functions from different	4561	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	4562	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	4563	different coroutines, and switch freely between both coroutines running
4332	the loop, as long as you don't confuse yourself). The only exception is	4564	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.	4565	that you must not do this from C<ev_periodic> reschedule callbacks.
4334		4566
4335	Care has been taken to ensure that libev does not keep local state inside	4567	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	4568	C<ev_run>, and other calls do not usually allow for coroutine switches as
4337	they do not call any callbacks.	4569	they do not call any callbacks.
4338		4570
4339	=head2 COMPILER WARNINGS	4571	=head2 COMPILER WARNINGS
4340		4572
4341	Depending on your compiler and compiler settings, you might get no or a	4573	Depending on your compiler and compiler settings, you might get no or a
…		…
4352	maintainable.	4584	maintainable.
4353		4585
4354	And of course, some compiler warnings are just plain stupid, or simply	4586	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	4587	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	4588	seems to warn about). For example, certain older gcc versions had some
4357	warnings that resulted an extreme number of false positives. These have	4589	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	4590	been fixed, but some people still insist on making code warn-free with
4359	such buggy versions.	4591	such buggy versions.
4360		4592
4361	While libev is written to generate as few warnings as possible,	4593	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	4594	"warn-free" code is not a goal, and it is recommended not to build libev
…		…
4398	I suggest using suppression lists.	4630	I suggest using suppression lists.
4399		4631
4400		4632
4401	=head1 PORTABILITY NOTES	4633	=head1 PORTABILITY NOTES
4402		4634
		4635	=head2 GNU/LINUX 32 BIT LIMITATIONS
		4636
		4637	GNU/Linux is the only common platform that supports 64 bit file/large file
		4638	interfaces but I<disables> them by default.
		4639
		4640	That means that libev compiled in the default environment doesn't support
		4641	files larger than 2GiB or so, which mainly affects C<ev_stat> watchers.
		4642
		4643	Unfortunately, many programs try to work around this GNU/Linux issue
		4644	by enabling the large file API, which makes them incompatible with the
		4645	standard libev compiled for their system.
		4646
		4647	Likewise, libev cannot enable the large file API itself as this would
		4648	suddenly make it incompatible to the default compile time environment,
		4649	i.e. all programs not using special compile switches.
		4650
		4651	=head2 OS/X AND DARWIN BUGS
		4652
		4653	The whole thing is a bug if you ask me - basically any system interface
		4654	you touch is broken, whether it is locales, poll, kqueue or even the
		4655	OpenGL drivers.
		4656
		4657	=head3 C<kqueue> is buggy
		4658
		4659	The kqueue syscall is broken in all known versions - most versions support
		4660	only sockets, many support pipes.
		4661
		4662	Libev tries to work around this by not using C<kqueue> by default on this
		4663	rotten platform, but of course you can still ask for it when creating a
		4664	loop - embedding a socket-only kqueue loop into a select-based one is
		4665	probably going to work well.
		4666
		4667	=head3 C<poll> is buggy
		4668
		4669	Instead of fixing C<kqueue>, Apple replaced their (working) C<poll>
		4670	implementation by something calling C<kqueue> internally around the 10.5.6
		4671	release, so now C<kqueue> I<and> C<poll> are broken.
		4672
		4673	Libev tries to work around this by not using C<poll> by default on
		4674	this rotten platform, but of course you can still ask for it when creating
		4675	a loop.
		4676
		4677	=head3 C<select> is buggy
		4678
		4679	All that's left is C<select>, and of course Apple found a way to fuck this
		4680	one up as well: On OS/X, C<select> actively limits the number of file
		4681	descriptors you can pass in to 1024 - your program suddenly crashes when
		4682	you use more.
		4683
		4684	There is an undocumented "workaround" for this - defining
		4685	C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should>
		4686	work on OS/X.
		4687
		4688	=head2 SOLARIS PROBLEMS AND WORKAROUNDS
		4689
		4690	=head3 C<errno> reentrancy
		4691
		4692	The default compile environment on Solaris is unfortunately so
		4693	thread-unsafe that you can't even use components/libraries compiled
		4694	without C<-D_REENTRANT> in a threaded program, which, of course, isn't
		4695	defined by default. A valid, if stupid, implementation choice.
		4696
		4697	If you want to use libev in threaded environments you have to make sure
		4698	it's compiled with C<_REENTRANT> defined.
		4699
		4700	=head3 Event port backend
		4701
		4702	The scalable event interface for Solaris is called "event
		4703	ports". Unfortunately, this mechanism is very buggy in all major
		4704	releases. If you run into high CPU usage, your program freezes or you get
		4705	a large number of spurious wakeups, make sure you have all the relevant
		4706	and latest kernel patches applied. No, I don't know which ones, but there
		4707	are multiple ones to apply, and afterwards, event ports actually work
		4708	great.
		4709
		4710	If you can't get it to work, you can try running the program by setting
		4711	the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and
		4712	C<select> backends.
		4713
		4714	=head2 AIX POLL BUG
		4715
		4716	AIX unfortunately has a broken C<poll.h> header. Libev works around
		4717	this by trying to avoid the poll backend altogether (i.e. it's not even
		4718	compiled in), which normally isn't a big problem as C<select> works fine
		4719	with large bitsets on AIX, and AIX is dead anyway.
		4720
4403	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS	4721	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
		4722
		4723	=head3 General issues
4404		4724
4405	Win32 doesn't support any of the standards (e.g. POSIX) that libev	4725	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	4726	requires, and its I/O model is fundamentally incompatible with the POSIX
4407	model. Libev still offers limited functionality on this platform in	4727	model. Libev still offers limited functionality on this platform in
4408	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	4728	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
4409	descriptors. This only applies when using Win32 natively, not when using	4729	descriptors. This only applies when using Win32 natively, not when using
4410	e.g. cygwin.	4730	e.g. cygwin. Actually, it only applies to the microsofts own compilers,
		4731	as every compielr comes with a slightly differently broken/incompatible
		4732	environment.
4411		4733
4412	Lifting these limitations would basically require the full	4734	Lifting these limitations would basically require the full
4413	re-implementation of the I/O system. If you are into these kinds of	4735	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	4736	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).	4737	also that glib is the slowest event library known to man).
4416		4738
4417	There is no supported compilation method available on windows except	4739	There is no supported compilation method available on windows except
4418	embedding it into other applications.	4740	embedding it into other applications.
4419		4741
4420	Sensible signal handling is officially unsupported by Microsoft - libev	4742	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!):	4770	you do I<not> compile the F<ev.c> or any other embedded source files!):
4449		4771
4450	#include "evwrap.h"	4772	#include "evwrap.h"
4451	#include "ev.c"	4773	#include "ev.c"
4452		4774
4453	=over 4
4454
4455	=item The winsocket select function	4775	=head3 The winsocket C<select> function
4456		4776
4457	The winsocket C<select> function doesn't follow POSIX in that it	4777	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	4778	requires socket I<handles> and not socket I<file descriptors> (it is
4459	also extremely buggy). This makes select very inefficient, and also	4779	also extremely buggy). This makes select very inefficient, and also
4460	requires a mapping from file descriptors to socket handles (the Microsoft	4780	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 */	4789	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
4470		4790
4471	Note that winsockets handling of fd sets is O(n), so you can easily get a	4791	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.	4792	complexity in the O(n²) range when using win32.
4473		4793
4474	=item Limited number of file descriptors	4794	=head3 Limited number of file descriptors
4475		4795
4476	Windows has numerous arbitrary (and low) limits on things.	4796	Windows has numerous arbitrary (and low) limits on things.
4477		4797
4478	Early versions of winsocket's select only supported waiting for a maximum	4798	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	4799	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	4814	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,	4815	(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	4816	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.	4817	the cost of calling select (O(n²)) will likely make this unworkable.
4498		4818
4499	=back
4500
4501	=head2 PORTABILITY REQUIREMENTS	4819	=head2 PORTABILITY REQUIREMENTS
4502		4820
4503	In addition to a working ISO-C implementation and of course the	4821	In addition to a working ISO-C implementation and of course the
4504	backend-specific APIs, libev relies on a few additional extensions:	4822	backend-specific APIs, libev relies on a few additional extensions:
4505		4823
…		…
4511	Libev assumes not only that all watcher pointers have the same internal	4829	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	4830	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	4831	assumes that the same (machine) code can be used to call any watcher
4514	callback: The watcher callbacks have different type signatures, but libev	4832	callback: The watcher callbacks have different type signatures, but libev
4515	calls them using an C<ev_watcher *> internally.	4833	calls them using an C<ev_watcher *> internally.
		4834
		4835	=item pointer accesses must be thread-atomic
		4836
		4837	Accessing a pointer value must be atomic, it must both be readable and
		4838	writable in one piece - this is the case on all current architectures.
4516		4839
4517	=item C<sig_atomic_t volatile> must be thread-atomic as well	4840	=item C<sig_atomic_t volatile> must be thread-atomic as well
4518		4841
4519	The type C<sig_atomic_t volatile> (or whatever is defined as	4842	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	4843	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different
…		…
4543	watchers.	4866	watchers.
4544		4867
4545	=item C<double> must hold a time value in seconds with enough accuracy	4868	=item C<double> must hold a time value in seconds with enough accuracy
4546		4869
4547	The type C<double> is used to represent timestamps. It is required to	4870	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	4871	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	4872	good enough for at least into the year 4000 with millisecond accuracy
		4873	(the design goal for libev). This requirement is overfulfilled by
4550	implementations implementing IEEE 754, which is basically all existing	4874	implementations using IEEE 754, which is basically all existing ones. With
4551	ones. With IEEE 754 doubles, you get microsecond accuracy until at least	4875	IEEE 754 doubles, you get microsecond accuracy until at least 2200.
4552	2200.
4553		4876
4554	=back	4877	=back
4555		4878
4556	If you know of other additional requirements drop me a note.	4879	If you know of other additional requirements drop me a note.
4557		4880
…		…
4627	=back	4950	=back
4628		4951
4629		4952
4630	=head1 PORTING FROM LIBEV 3.X TO 4.X	4953	=head1 PORTING FROM LIBEV 3.X TO 4.X
4631		4954
4632	The major version 4 introduced some minor incompatible changes to the API.	4955	The major version 4 introduced some incompatible changes to the API.
4633		4956
4634	At the moment, the C<ev.h> header file tries to implement superficial	4957	At the moment, the C<ev.h> header file provides compatibility definitions
4635	compatibility, so most programs should still compile. Those might be	4958	for all changes, so most programs should still compile. The compatibility
4636	removed in later versions of libev, so better update early than late.	4959	layer might be removed in later versions of libev, so better update to the
		4960	new API early than late.
4637		4961
4638	=over 4	4962	=over 4
4639		4963
4640	=item C<ev_loop_count> renamed to C<ev_iteration>	4964	=item C<EV_COMPAT3> backwards compatibility mechanism
4641		4965
4642	=item C<ev_loop_depth> renamed to C<ev_depth>	4966	The backward compatibility mechanism can be controlled by
		4967	C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING>
		4968	section.
4643		4969
4644	=item C<ev_loop_verify> renamed to C<ev_verify>	4970	=item C<ev_default_destroy> and C<ev_default_fork> have been removed
		4971
		4972	These calls can be replaced easily by their C<ev_loop_xxx> counterparts:
		4973
		4974	ev_loop_destroy (EV_DEFAULT_UC);
		4975	ev_loop_fork (EV_DEFAULT);
		4976
		4977	=item function/symbol renames
		4978
		4979	A number of functions and symbols have been renamed:
		4980
		4981	ev_loop => ev_run
		4982	EVLOOP_NONBLOCK => EVRUN_NOWAIT
		4983	EVLOOP_ONESHOT => EVRUN_ONCE
		4984
		4985	ev_unloop => ev_break
		4986	EVUNLOOP_CANCEL => EVBREAK_CANCEL
		4987	EVUNLOOP_ONE => EVBREAK_ONE
		4988	EVUNLOOP_ALL => EVBREAK_ALL
		4989
		4990	EV_TIMEOUT => EV_TIMER
		4991
		4992	ev_loop_count => ev_iteration
		4993	ev_loop_depth => ev_depth
		4994	ev_loop_verify => ev_verify
4645		4995
4646	Most functions working on C<struct ev_loop> objects don't have an	4996	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	4997	C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and
		4998	associated constants have been renamed to not collide with the C<struct
		4999	ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme
		5000	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	5001	C<ev_loop_fork> because it would otherwise clash with the C<ev_fork>
4649	C<ev_fork> typedef.	5002	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		5003
4660	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>	5004	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>
4661		5005
4662	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different	5006	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different
4663	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile	5007	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile
…		…
4670		5014
4671	=over 4	5015	=over 4
4672		5016
4673	=item active	5017	=item active
4674		5018
4675	A watcher is active as long as it has been started (has been attached to	5019	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).	5020	See L<WATCHER STATES> for details.
4677		5021
4678	=item application	5022	=item application
4679		5023
4680	In this document, an application is whatever is using libev.	5024	In this document, an application is whatever is using libev.
		5025
		5026	=item backend
		5027
		5028	The part of the code dealing with the operating system interfaces.
4681		5029
4682	=item callback	5030	=item callback
4683		5031
4684	The address of a function that is called when some event has been	5032	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	5033	detected. Callbacks are being passed the event loop, the watcher that
4686	received the event, and the actual event bitset.	5034	received the event, and the actual event bitset.
4687		5035
4688	=item callback invocation	5036	=item callback/watcher invocation
4689		5037
4690	The act of calling the callback associated with a watcher.	5038	The act of calling the callback associated with a watcher.
4691		5039
4692	=item event	5040	=item event
4693		5041
…		…
4712	The model used to describe how an event loop handles and processes	5060	The model used to describe how an event loop handles and processes
4713	watchers and events.	5061	watchers and events.
4714		5062
4715	=item pending	5063	=item pending
4716		5064
4717	A watcher is pending as soon as the corresponding event has been detected,	5065	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	5066	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		5067
4724	=item real time	5068	=item real time
4725		5069
4726	The physical time that is observed. It is apparently strictly monotonic :)	5070	The physical time that is observed. It is apparently strictly monotonic :)
4727		5071
…		…
4734	=item watcher	5078	=item watcher
4735		5079
4736	A data structure that describes interest in certain events. Watchers need	5080	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.	5081	to be started (attached to an event loop) before they can receive events.
4738		5082
4739	=item watcher invocation
4740
4741	The act of calling the callback associated with a watcher.
4742
4743	=back	5083	=back
4744		5084
4745	=head1 AUTHOR	5085	=head1 AUTHOR
4746		5086
4747	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson.	5087	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael
		5088	Magnusson and Emanuele Giaquinta.
4748		5089

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