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…		…
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		82
83	=head1 ABOUT LIBEV	83	=head1 ABOUT LIBEV
84		84
85	Libev is an event loop: you register interest in certain events (such as a	85	Libev is an event loop: you register interest in certain events (such as a
…		…
98	=head2 FEATURES	98	=head2 FEATURES
99		99
100	Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the	100	Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the
101	BSD-specific C<kqueue> and the Solaris-specific event port mechanisms	101	BSD-specific C<kqueue> and the Solaris-specific event port mechanisms
102	for file descriptor events (C<ev_io>), the Linux C<inotify> interface	102	for file descriptor events (C<ev_io>), the Linux C<inotify> interface
103	(for C<ev_stat>), relative timers (C<ev_timer>), absolute timers	103	(for C<ev_stat>), Linux eventfd/signalfd (for faster and cleaner
104	with customised rescheduling (C<ev_periodic>), synchronous signals	104	inter-thread wakeup (C<ev_async>)/signal handling (C<ev_signal>)) relative
105	(C<ev_signal>), process status change events (C<ev_child>), and event	105	timers (C<ev_timer>), absolute timers with customised rescheduling
106	watchers dealing with the event loop mechanism itself (C<ev_idle>,	106	(C<ev_periodic>), synchronous signals (C<ev_signal>), process status
107	C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as	107	change events (C<ev_child>), and event watchers dealing with the event
108	file watchers (C<ev_stat>) and even limited support for fork events	108	loop mechanism itself (C<ev_idle>, C<ev_embed>, C<ev_prepare> and
109	(C<ev_fork>).	109	C<ev_check> watchers) as well as file watchers (C<ev_stat>) and even
		110	limited support for fork events (C<ev_fork>).
110		111
111	It also is quite fast (see this	112	It also is quite fast (see this
112	L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent	113	L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent
113	for example).	114	for example).
114		115
…		…
117	Libev is very configurable. In this manual the default (and most common)	118	Libev is very configurable. In this manual the default (and most common)
118	configuration will be described, which supports multiple event loops. For	119	configuration will be described, which supports multiple event loops. For
119	more info about various configuration options please have a look at	120	more info about various configuration options please have a look at
120	B<EMBED> section in this manual. If libev was configured without support	121	B<EMBED> section in this manual. If libev was configured without support
121	for multiple event loops, then all functions taking an initial argument of	122	for multiple event loops, then all functions taking an initial argument of
122	name C<loop> (which is always of type C<ev_loop *>) will not have	123	name C<loop> (which is always of type C<struct ev_loop *>) will not have
123	this argument.	124	this argument.
124		125
125	=head2 TIME REPRESENTATION	126	=head2 TIME REPRESENTATION
126		127
127	Libev represents time as a single floating point number, representing	128	Libev represents time as a single floating point number, representing
128	the (fractional) number of seconds since the (POSIX) epoch (somewhere	129	the (fractional) number of seconds since the (POSIX) epoch (in practice
129	near the beginning of 1970, details are complicated, don't ask). This	130	somewhere near the beginning of 1970, details are complicated, don't
130	type is called C<ev_tstamp>, which is what you should use too. It usually	131	ask). This type is called C<ev_tstamp>, which is what you should use
131	aliases to the C<double> type in C. When you need to do any calculations	132	too. It usually aliases to the C<double> type in C. When you need to do
132	on it, you should treat it as some floating point value. Unlike the name	133	any calculations on it, you should treat it as some floating point value.
		134
133	component C<stamp> might indicate, it is also used for time differences	135	Unlike the name component C<stamp> might indicate, it is also used for
134	throughout libev.	136	time differences (e.g. delays) throughout libev.
135		137
136	=head1 ERROR HANDLING	138	=head1 ERROR HANDLING
137		139
138	Libev knows three classes of errors: operating system errors, usage errors	140	Libev knows three classes of errors: operating system errors, usage errors
139	and internal errors (bugs).	141	and internal errors (bugs).
…		…
163		165
164	=item ev_tstamp ev_time ()	166	=item ev_tstamp ev_time ()
165		167
166	Returns the current time as libev would use it. Please note that the	168	Returns the current time as libev would use it. Please note that the
167	C<ev_now> function is usually faster and also often returns the timestamp	169	C<ev_now> function is usually faster and also often returns the timestamp
168	you actually want to know.	170	you actually want to know. Also interesting is the combination of
		171	C<ev_update_now> and C<ev_now>.
169		172
170	=item ev_sleep (ev_tstamp interval)	173	=item ev_sleep (ev_tstamp interval)
171		174
172	Sleep for the given interval: The current thread will be blocked until	175	Sleep for the given interval: The current thread will be blocked until
173	either it is interrupted or the given time interval has passed. Basically	176	either it is interrupted or the given time interval has passed. Basically
…		…
190	as this indicates an incompatible change. Minor versions are usually	193	as this indicates an incompatible change. Minor versions are usually
191	compatible to older versions, so a larger minor version alone is usually	194	compatible to older versions, so a larger minor version alone is usually
192	not a problem.	195	not a problem.
193		196
194	Example: Make sure we haven't accidentally been linked against the wrong	197	Example: Make sure we haven't accidentally been linked against the wrong
195	version.	198	version (note, however, that this will not detect other ABI mismatches,
		199	such as LFS or reentrancy).
196		200
197	assert (("libev version mismatch",	201	assert (("libev version mismatch",
198	ev_version_major () == EV_VERSION_MAJOR	202	ev_version_major () == EV_VERSION_MAJOR
199	&& ev_version_minor () >= EV_VERSION_MINOR));	203	&& ev_version_minor () >= EV_VERSION_MINOR));
200		204
…		…
211	assert (("sorry, no epoll, no sex",	215	assert (("sorry, no epoll, no sex",
212	ev_supported_backends () & EVBACKEND_EPOLL));	216	ev_supported_backends () & EVBACKEND_EPOLL));
213		217
214	=item unsigned int ev_recommended_backends ()	218	=item unsigned int ev_recommended_backends ()
215		219
216	Return the set of all backends compiled into this binary of libev and also	220	Return the set of all backends compiled into this binary of libev and
217	recommended for this platform. This set is often smaller than the one	221	also recommended for this platform, meaning it will work for most file
		222	descriptor types. This set is often smaller than the one returned by
218	returned by C<ev_supported_backends>, as for example kqueue is broken on	223	C<ev_supported_backends>, as for example kqueue is broken on most BSDs
219	most BSDs and will not be auto-detected unless you explicitly request it	224	and will not be auto-detected unless you explicitly request it (assuming
220	(assuming you know what you are doing). This is the set of backends that	225	you know what you are doing). This is the set of backends that libev will
221	libev will probe for if you specify no backends explicitly.	226	probe for if you specify no backends explicitly.
222		227
223	=item unsigned int ev_embeddable_backends ()	228	=item unsigned int ev_embeddable_backends ()
224		229
225	Returns the set of backends that are embeddable in other event loops. This	230	Returns the set of backends that are embeddable in other event loops. This
226	is the theoretical, all-platform, value. To find which backends	231	value is platform-specific but can include backends not available on the
227	might be supported on the current system, you would need to look at	232	current system. To find which embeddable backends might be supported on
228	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for	233	the current system, you would need to look at C<ev_embeddable_backends ()
229	recommended ones.	234	& ev_supported_backends ()>, likewise for recommended ones.
230		235
231	See the description of C<ev_embed> watchers for more info.	236	See the description of C<ev_embed> watchers for more info.
232		237
233	=item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT]	238	=item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT]
234		239
…		…
288	...	293	...
289	ev_set_syserr_cb (fatal_error);	294	ev_set_syserr_cb (fatal_error);
290		295
291	=back	296	=back
292		297
293	=head1 FUNCTIONS CONTROLLING THE EVENT LOOP	298	=head1 FUNCTIONS CONTROLLING EVENT LOOPS
294		299
295	An event loop is described by a C<struct ev_loop *> (the C<struct>	300	An event loop is described by a C<struct ev_loop *> (the C<struct> is
296	is I<not> optional in this case, as there is also an C<ev_loop>	301	I<not> optional in this case unless libev 3 compatibility is disabled, as
297	I<function>).	302	libev 3 had an C<ev_loop> function colliding with the struct name).
298		303
299	The library knows two types of such loops, the I<default> loop, which	304	The library knows two types of such loops, the I<default> loop, which
300	supports signals and child events, and dynamically created loops which do	305	supports signals and child events, and dynamically created event loops
301	not.	306	which do not.
302		307
303	=over 4	308	=over 4
304		309
305	=item struct ev_loop *ev_default_loop (unsigned int flags)	310	=item struct ev_loop *ev_default_loop (unsigned int flags)
306		311
307	This will initialise the default event loop if it hasn't been initialised	312	This returns the "default" event loop object, which is what you should
308	yet and return it. If the default loop could not be initialised, returns	313	normally use when you just need "the event loop". Event loop objects and
309	false. If it already was initialised it simply returns it (and ignores the	314	the C<flags> parameter are described in more detail in the entry for
310	flags. If that is troubling you, check C<ev_backend ()> afterwards).	315	C<ev_loop_new>.
		316
		317	If the default loop is already initialised then this function simply
		318	returns it (and ignores the flags. If that is troubling you, check
		319	C<ev_backend ()> afterwards). Otherwise it will create it with the given
		320	flags, which should almost always be C<0>, unless the caller is also the
		321	one calling C<ev_run> or otherwise qualifies as "the main program".
311		322
312	If you don't know what event loop to use, use the one returned from this	323	If you don't know what event loop to use, use the one returned from this
313	function.	324	function (or via the C<EV_DEFAULT> macro).
314		325
315	Note that this function is I<not> thread-safe, so if you want to use it	326	Note that this function is I<not> thread-safe, so if you want to use it
316	from multiple threads, you have to lock (note also that this is unlikely,	327	from multiple threads, you have to employ some kind of mutex (note also
317	as loops cannot be shared easily between threads anyway).	328	that this case is unlikely, as loops cannot be shared easily between
		329	threads anyway).
318		330
319	The default loop is the only loop that can handle C<ev_signal> and	331	The default loop is the only loop that can handle C<ev_child> watchers,
320	C<ev_child> watchers, and to do this, it always registers a handler	332	and to do this, it always registers a handler for C<SIGCHLD>. If this is
321	for C<SIGCHLD>. If this is a problem for your application you can either	333	a problem for your application you can either create a dynamic loop with
322	create a dynamic loop with C<ev_loop_new> that doesn't do that, or you	334	C<ev_loop_new> which doesn't do that, or you can simply overwrite the
323	can simply overwrite the C<SIGCHLD> signal handler I<after> calling	335	C<SIGCHLD> signal handler I<after> calling C<ev_default_init>.
324	C<ev_default_init>.	336
		337	Example: This is the most typical usage.
		338
		339	if (!ev_default_loop (0))
		340	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
		341
		342	Example: Restrict libev to the select and poll backends, and do not allow
		343	environment settings to be taken into account:
		344
		345	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
		346
		347	=item struct ev_loop *ev_loop_new (unsigned int flags)
		348
		349	This will create and initialise a new event loop object. If the loop
		350	could not be initialised, returns false.
		351
		352	Note that this function I<is> thread-safe, and one common way to use
		353	libev with threads is indeed to create one loop per thread, and using the
		354	default loop in the "main" or "initial" thread.
325		355
326	The flags argument can be used to specify special behaviour or specific	356	The flags argument can be used to specify special behaviour or specific
327	backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>).	357	backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>).
328		358
329	The following flags are supported:	359	The following flags are supported:
…		…
344	useful to try out specific backends to test their performance, or to work	374	useful to try out specific backends to test their performance, or to work
345	around bugs.	375	around bugs.
346		376
347	=item C<EVFLAG_FORKCHECK>	377	=item C<EVFLAG_FORKCHECK>
348		378
349	Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after	379	Instead of calling C<ev_loop_fork> manually after a fork, you can also
350	a fork, you can also make libev check for a fork in each iteration by	380	make libev check for a fork in each iteration by enabling this flag.
351	enabling this flag.
352		381
353	This works by calling C<getpid ()> on every iteration of the loop,	382	This works by calling C<getpid ()> on every iteration of the loop,
354	and thus this might slow down your event loop if you do a lot of loop	383	and thus this might slow down your event loop if you do a lot of loop
355	iterations and little real work, but is usually not noticeable (on my	384	iterations and little real work, but is usually not noticeable (on my
356	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence	385	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence
…		…
369	When this flag is specified, then libev will not attempt to use the	398	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	399	I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and
371	testing, this flag can be useful to conserve inotify file descriptors, as	400	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.	401	otherwise each loop using C<ev_stat> watchers consumes one inotify handle.
373		402
374	=item C<EVFLAG_NOSIGNALFD>	403	=item C<EVFLAG_SIGNALFD>
375		404
376	When this flag is specified, then libev will not attempt to use the	405	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 is	406	I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This API
378	probably only useful to work around any bugs in libev. Consequently, this	407	delivers signals synchronously, which makes it both faster and might make
379	flag might go away once the signalfd functionality is considered stable,	408	it possible to get the queued signal data. It can also simplify signal
380	so it's useful mostly in environment variables and not in program code.	409	handling with threads, as long as you properly block signals in your
		410	threads that are not interested in handling them.
		411
		412	Signalfd will not be used by default as this changes your signal mask, and
		413	there are a lot of shoddy libraries and programs (glib's threadpool for
		414	example) that can't properly initialise their signal masks.
381		415
382	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	416	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
383		417
384	This is your standard select(2) backend. Not I<completely> standard, as	418	This is your standard select(2) backend. Not I<completely> standard, as
385	libev tries to roll its own fd_set with no limits on the number of fds,	419	libev tries to roll its own fd_set with no limits on the number of fds,
…		…
409		443
410	This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and	444	This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and
411	C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>.	445	C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>.
412		446
413	=item C<EVBACKEND_EPOLL> (value 4, Linux)	447	=item C<EVBACKEND_EPOLL> (value 4, Linux)
		448
		449	Use the linux-specific epoll(7) interface (for both pre- and post-2.6.9
		450	kernels).
414		451
415	For few fds, this backend is a bit little slower than poll and select,	452	For few fds, this backend is a bit little slower than poll and select,
416	but it scales phenomenally better. While poll and select usually scale	453	but it scales phenomenally better. While poll and select usually scale
417	like O(total_fds) where n is the total number of fds (or the highest fd),	454	like O(total_fds) where n is the total number of fds (or the highest fd),
418	epoll scales either O(1) or O(active_fds).	455	epoll scales either O(1) or O(active_fds).
…		…
430	of course I<doesn't>, and epoll just loves to report events for totally	467	of course I<doesn't>, and epoll just loves to report events for totally
431	I<different> file descriptors (even already closed ones, so one cannot	468	I<different> file descriptors (even already closed ones, so one cannot
432	even remove them from the set) than registered in the set (especially	469	even remove them from the set) than registered in the set (especially
433	on SMP systems). Libev tries to counter these spurious notifications by	470	on SMP systems). Libev tries to counter these spurious notifications by
434	employing an additional generation counter and comparing that against the	471	employing an additional generation counter and comparing that against the
435	events to filter out spurious ones, recreating the set when required.	472	events to filter out spurious ones, recreating the set when required. Last
		473	not least, it also refuses to work with some file descriptors which work
		474	perfectly fine with C<select> (files, many character devices...).
436		475
437	While stopping, setting and starting an I/O watcher in the same iteration	476	While stopping, setting and starting an I/O watcher in the same iteration
438	will result in some caching, there is still a system call per such	477	will result in some caching, there is still a system call per such
439	incident (because the same I<file descriptor> could point to a different	478	incident (because the same I<file descriptor> could point to a different
440	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed	479	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed
…		…
538	If one or more of the backend flags are or'ed into the flags value,	577	If one or more of the backend flags are or'ed into the flags value,
539	then only these backends will be tried (in the reverse order as listed	578	then only these backends will be tried (in the reverse order as listed
540	here). If none are specified, all backends in C<ev_recommended_backends	579	here). If none are specified, all backends in C<ev_recommended_backends
541	()> will be tried.	580	()> will be tried.
542		581
543	Example: This is the most typical usage.
544
545	if (!ev_default_loop (0))
546	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
547
548	Example: Restrict libev to the select and poll backends, and do not allow
549	environment settings to be taken into account:
550
551	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
552
553	Example: Use whatever libev has to offer, but make sure that kqueue is
554	used if available (warning, breaks stuff, best use only with your own
555	private event loop and only if you know the OS supports your types of
556	fds):
557
558	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
559
560	=item struct ev_loop *ev_loop_new (unsigned int flags)
561
562	Similar to C<ev_default_loop>, but always creates a new event loop that is
563	always distinct from the default loop. Unlike the default loop, it cannot
564	handle signal and child watchers, and attempts to do so will be greeted by
565	undefined behaviour (or a failed assertion if assertions are enabled).
566
567	Note that this function I<is> thread-safe, and the recommended way to use
568	libev with threads is indeed to create one loop per thread, and using the
569	default loop in the "main" or "initial" thread.
570
571	Example: Try to create a event loop that uses epoll and nothing else.	582	Example: Try to create a event loop that uses epoll and nothing else.
572		583
573	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	584	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
574	if (!epoller)	585	if (!epoller)
575	fatal ("no epoll found here, maybe it hides under your chair");	586	fatal ("no epoll found here, maybe it hides under your chair");
576		587
		588	Example: Use whatever libev has to offer, but make sure that kqueue is
		589	used if available.
		590
		591	struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE);
		592
577	=item ev_default_destroy ()	593	=item ev_loop_destroy (loop)
578		594
579	Destroys the default loop again (frees all memory and kernel state	595	Destroys an event loop object (frees all memory and kernel state
580	etc.). None of the active event watchers will be stopped in the normal	596	etc.). None of the active event watchers will be stopped in the normal
581	sense, so e.g. C<ev_is_active> might still return true. It is your	597	sense, so e.g. C<ev_is_active> might still return true. It is your
582	responsibility to either stop all watchers cleanly yourself I<before>	598	responsibility to either stop all watchers cleanly yourself I<before>
583	calling this function, or cope with the fact afterwards (which is usually	599	calling this function, or cope with the fact afterwards (which is usually
584	the easiest thing, you can just ignore the watchers and/or C<free ()> them	600	the easiest thing, you can just ignore the watchers and/or C<free ()> them
…		…
586		602
587	Note that certain global state, such as signal state (and installed signal	603	Note that certain global state, such as signal state (and installed signal
588	handlers), will not be freed by this function, and related watchers (such	604	handlers), will not be freed by this function, and related watchers (such
589	as signal and child watchers) would need to be stopped manually.	605	as signal and child watchers) would need to be stopped manually.
590		606
591	In general it is not advisable to call this function except in the	607	This function is normally used on loop objects allocated by
592	rare occasion where you really need to free e.g. the signal handling	608	C<ev_loop_new>, but it can also be used on the default loop returned by
		609	C<ev_default_loop>, in which case it is not thread-safe.
		610
		611	Note that it is not advisable to call this function on the default loop
		612	except in the rare occasion where you really need to free it's resources.
593	pipe fds. If you need dynamically allocated loops it is better to use	613	If you need dynamically allocated loops it is better to use C<ev_loop_new>
594	C<ev_loop_new> and C<ev_loop_destroy>).	614	and C<ev_loop_destroy>.
595		615
596	=item ev_loop_destroy (loop)	616	=item ev_loop_fork (loop)
597		617
598	Like C<ev_default_destroy>, but destroys an event loop created by an
599	earlier call to C<ev_loop_new>.
600
601	=item ev_default_fork ()
602
603	This function sets a flag that causes subsequent C<ev_loop> iterations	618	This function sets a flag that causes subsequent C<ev_run> iterations to
604	to reinitialise the kernel state for backends that have one. Despite the	619	reinitialise the kernel state for backends that have one. Despite the
605	name, you can call it anytime, but it makes most sense after forking, in	620	name, you can call it anytime, but it makes most sense after forking, in
606	the child process (or both child and parent, but that again makes little	621	the child process. You I<must> call it (or use C<EVFLAG_FORKCHECK>) in the
607	sense). You I<must> call it in the child before using any of the libev	622	child before resuming or calling C<ev_run>.
608	functions, and it will only take effect at the next C<ev_loop> iteration.	623
		624	Again, you I<have> to call it on I<any> loop that you want to re-use after
		625	a fork, I<even if you do not plan to use the loop in the parent>. This is
		626	because some kernel interfaces *cough* I<kqueue> *cough* do funny things
		627	during fork.
609		628
610	On the other hand, you only need to call this function in the child	629	On the other hand, you only need to call this function in the child
611	process if and only if you want to use the event library in the child. If	630	process if and only if you want to use the event loop in the child. If
612	you just fork+exec, you don't have to call it at all.	631	you just fork+exec or create a new loop in the child, you don't have to
		632	call it at all (in fact, C<epoll> is so badly broken that it makes a
		633	difference, but libev will usually detect this case on its own and do a
		634	costly reset of the backend).
613		635
614	The function itself is quite fast and it's usually not a problem to call	636	The function itself is quite fast and it's usually not a problem to call
615	it just in case after a fork. To make this easy, the function will fit in	637	it just in case after a fork.
616	quite nicely into a call to C<pthread_atfork>:
617		638
		639	Example: Automate calling C<ev_loop_fork> on the default loop when
		640	using pthreads.
		641
		642	static void
		643	post_fork_child (void)
		644	{
		645	ev_loop_fork (EV_DEFAULT);
		646	}
		647
		648	...
618	pthread_atfork (0, 0, ev_default_fork);	649	pthread_atfork (0, 0, post_fork_child);
619
620	=item ev_loop_fork (loop)
621
622	Like C<ev_default_fork>, but acts on an event loop created by
623	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
624	after fork that you want to re-use in the child, and how you do this is
625	entirely your own problem.
626		650
627	=item int ev_is_default_loop (loop)	651	=item int ev_is_default_loop (loop)
628		652
629	Returns true when the given loop is, in fact, the default loop, and false	653	Returns true when the given loop is, in fact, the default loop, and false
630	otherwise.	654	otherwise.
631		655
632	=item unsigned int ev_loop_count (loop)	656	=item unsigned int ev_iteration (loop)
633		657
634	Returns the count of loop iterations for the loop, which is identical to	658	Returns the current iteration count for the event loop, which is identical
635	the number of times libev did poll for new events. It starts at C<0> and	659	to the number of times libev did poll for new events. It starts at C<0>
636	happily wraps around with enough iterations.	660	and happily wraps around with enough iterations.
637		661
638	This value can sometimes be useful as a generation counter of sorts (it	662	This value can sometimes be useful as a generation counter of sorts (it
639	"ticks" the number of loop iterations), as it roughly corresponds with	663	"ticks" the number of loop iterations), as it roughly corresponds with
640	C<ev_prepare> and C<ev_check> calls.	664	C<ev_prepare> and C<ev_check> calls - and is incremented between the
		665	prepare and check phases.
641		666
642	=item unsigned int ev_loop_depth (loop)	667	=item unsigned int ev_depth (loop)
643		668
644	Returns the number of times C<ev_loop> was entered minus the number of	669	Returns the number of times C<ev_run> was entered minus the number of
645	times C<ev_loop> was exited, in other words, the recursion depth.	670	times C<ev_run> was exited, in other words, the recursion depth.
646		671
647	Outside C<ev_loop>, this number is zero. In a callback, this number is	672	Outside C<ev_run>, this number is zero. In a callback, this number is
648	C<1>, unless C<ev_loop> was invoked recursively (or from another thread),	673	C<1>, unless C<ev_run> was invoked recursively (or from another thread),
649	in which case it is higher.	674	in which case it is higher.
650		675
651	Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread	676	Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread
652	etc.), doesn't count as exit.	677	etc.), doesn't count as "exit" - consider this as a hint to avoid such
		678	ungentleman-like behaviour unless it's really convenient.
653		679
654	=item unsigned int ev_backend (loop)	680	=item unsigned int ev_backend (loop)
655		681
656	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	682	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
657	use.	683	use.
…		…
666		692
667	=item ev_now_update (loop)	693	=item ev_now_update (loop)
668		694
669	Establishes the current time by querying the kernel, updating the time	695	Establishes the current time by querying the kernel, updating the time
670	returned by C<ev_now ()> in the progress. This is a costly operation and	696	returned by C<ev_now ()> in the progress. This is a costly operation and
671	is usually done automatically within C<ev_loop ()>.	697	is usually done automatically within C<ev_run ()>.
672		698
673	This function is rarely useful, but when some event callback runs for a	699	This function is rarely useful, but when some event callback runs for a
674	very long time without entering the event loop, updating libev's idea of	700	very long time without entering the event loop, updating libev's idea of
675	the current time is a good idea.	701	the current time is a good idea.
676		702
…		…
678		704
679	=item ev_suspend (loop)	705	=item ev_suspend (loop)
680		706
681	=item ev_resume (loop)	707	=item ev_resume (loop)
682		708
683	These two functions suspend and resume a loop, for use when the loop is	709	These two functions suspend and resume an event loop, for use when the
684	not used for a while and timeouts should not be processed.	710	loop is not used for a while and timeouts should not be processed.
685		711
686	A typical use case would be an interactive program such as a game: When	712	A typical use case would be an interactive program such as a game: When
687	the user presses C<^Z> to suspend the game and resumes it an hour later it	713	the user presses C<^Z> to suspend the game and resumes it an hour later it
688	would be best to handle timeouts as if no time had actually passed while	714	would be best to handle timeouts as if no time had actually passed while
689	the program was suspended. This can be achieved by calling C<ev_suspend>	715	the program was suspended. This can be achieved by calling C<ev_suspend>
…		…
691	C<ev_resume> directly afterwards to resume timer processing.	717	C<ev_resume> directly afterwards to resume timer processing.
692		718
693	Effectively, all C<ev_timer> watchers will be delayed by the time spend	719	Effectively, all C<ev_timer> watchers will be delayed by the time spend
694	between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers	720	between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers
695	will be rescheduled (that is, they will lose any events that would have	721	will be rescheduled (that is, they will lose any events that would have
696	occured while suspended).	722	occurred while suspended).
697		723
698	After calling C<ev_suspend> you B<must not> call I<any> function on the	724	After calling C<ev_suspend> you B<must not> call I<any> function on the
699	given loop other than C<ev_resume>, and you B<must not> call C<ev_resume>	725	given loop other than C<ev_resume>, and you B<must not> call C<ev_resume>
700	without a previous call to C<ev_suspend>.	726	without a previous call to C<ev_suspend>.
701		727
702	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the	728	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the
703	event loop time (see C<ev_now_update>).	729	event loop time (see C<ev_now_update>).
704		730
705	=item ev_loop (loop, int flags)	731	=item ev_run (loop, int flags)
706		732
707	Finally, this is it, the event handler. This function usually is called	733	Finally, this is it, the event handler. This function usually is called
708	after you initialised all your watchers and you want to start handling	734	after you have initialised all your watchers and you want to start
709	events.	735	handling events. It will ask the operating system for any new events, call
		736	the watcher callbacks, an then repeat the whole process indefinitely: This
		737	is why event loops are called I<loops>.
710		738
711	If the flags argument is specified as C<0>, it will not return until	739	If the flags argument is specified as C<0>, it will keep handling events
712	either no event watchers are active anymore or C<ev_unloop> was called.	740	until either no event watchers are active anymore or C<ev_break> was
		741	called.
713		742
714	Please note that an explicit C<ev_unloop> is usually better than	743	Please note that an explicit C<ev_break> is usually better than
715	relying on all watchers to be stopped when deciding when a program has	744	relying on all watchers to be stopped when deciding when a program has
716	finished (especially in interactive programs), but having a program	745	finished (especially in interactive programs), but having a program
717	that automatically loops as long as it has to and no longer by virtue	746	that automatically loops as long as it has to and no longer by virtue
718	of relying on its watchers stopping correctly, that is truly a thing of	747	of relying on its watchers stopping correctly, that is truly a thing of
719	beauty.	748	beauty.
720		749
721	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle	750	A flags value of C<EVRUN_NOWAIT> will look for new events, will handle
722	those events and any already outstanding ones, but will not block your	751	those events and any already outstanding ones, but will not wait and
723	process in case there are no events and will return after one iteration of	752	block your process in case there are no events and will return after one
724	the loop.	753	iteration of the loop. This is sometimes useful to poll and handle new
		754	events while doing lengthy calculations, to keep the program responsive.
725		755
726	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if	756	A flags value of C<EVRUN_ONCE> will look for new events (waiting if
727	necessary) and will handle those and any already outstanding ones. It	757	necessary) and will handle those and any already outstanding ones. It
728	will block your process until at least one new event arrives (which could	758	will block your process until at least one new event arrives (which could
729	be an event internal to libev itself, so there is no guarantee that a	759	be an event internal to libev itself, so there is no guarantee that a
730	user-registered callback will be called), and will return after one	760	user-registered callback will be called), and will return after one
731	iteration of the loop.	761	iteration of the loop.
732		762
733	This is useful if you are waiting for some external event in conjunction	763	This is useful if you are waiting for some external event in conjunction
734	with something not expressible using other libev watchers (i.e. "roll your	764	with something not expressible using other libev watchers (i.e. "roll your
735	own C<ev_loop>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is	765	own C<ev_run>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is
736	usually a better approach for this kind of thing.	766	usually a better approach for this kind of thing.
737		767
738	Here are the gory details of what C<ev_loop> does:	768	Here are the gory details of what C<ev_run> does:
739		769
		770	- Increment loop depth.
		771	- Reset the ev_break status.
740	- Before the first iteration, call any pending watchers.	772	- Before the first iteration, call any pending watchers.
		773	LOOP:
741	* If EVFLAG_FORKCHECK was used, check for a fork.	774	- If EVFLAG_FORKCHECK was used, check for a fork.
742	- If a fork was detected (by any means), queue and call all fork watchers.	775	- If a fork was detected (by any means), queue and call all fork watchers.
743	- Queue and call all prepare watchers.	776	- Queue and call all prepare watchers.
		777	- If ev_break was called, goto FINISH.
744	- If we have been forked, detach and recreate the kernel state	778	- If we have been forked, detach and recreate the kernel state
745	as to not disturb the other process.	779	as to not disturb the other process.
746	- Update the kernel state with all outstanding changes.	780	- Update the kernel state with all outstanding changes.
747	- Update the "event loop time" (ev_now ()).	781	- Update the "event loop time" (ev_now ()).
748	- Calculate for how long to sleep or block, if at all	782	- Calculate for how long to sleep or block, if at all
749	(active idle watchers, EVLOOP_NONBLOCK or not having	783	(active idle watchers, EVRUN_NOWAIT or not having
750	any active watchers at all will result in not sleeping).	784	any active watchers at all will result in not sleeping).
751	- Sleep if the I/O and timer collect interval say so.	785	- Sleep if the I/O and timer collect interval say so.
		786	- Increment loop iteration counter.
752	- Block the process, waiting for any events.	787	- Block the process, waiting for any events.
753	- Queue all outstanding I/O (fd) events.	788	- Queue all outstanding I/O (fd) events.
754	- Update the "event loop time" (ev_now ()), and do time jump adjustments.	789	- Update the "event loop time" (ev_now ()), and do time jump adjustments.
755	- Queue all expired timers.	790	- Queue all expired timers.
756	- Queue all expired periodics.	791	- Queue all expired periodics.
757	- Unless any events are pending now, queue all idle watchers.	792	- Queue all idle watchers with priority higher than that of pending events.
758	- Queue all check watchers.	793	- Queue all check watchers.
759	- Call all queued watchers in reverse order (i.e. check watchers first).	794	- Call all queued watchers in reverse order (i.e. check watchers first).
760	Signals and child watchers are implemented as I/O watchers, and will	795	Signals and child watchers are implemented as I/O watchers, and will
761	be handled here by queueing them when their watcher gets executed.	796	be handled here by queueing them when their watcher gets executed.
762	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	797	- If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT
763	were used, or there are no active watchers, return, otherwise	798	were used, or there are no active watchers, goto FINISH, otherwise
764	continue with step *.	799	continue with step LOOP.
		800	FINISH:
		801	- Reset the ev_break status iff it was EVBREAK_ONE.
		802	- Decrement the loop depth.
		803	- Return.
765		804
766	Example: Queue some jobs and then loop until no events are outstanding	805	Example: Queue some jobs and then loop until no events are outstanding
767	anymore.	806	anymore.
768		807
769	... queue jobs here, make sure they register event watchers as long	808	... queue jobs here, make sure they register event watchers as long
770	... as they still have work to do (even an idle watcher will do..)	809	... as they still have work to do (even an idle watcher will do..)
771	ev_loop (my_loop, 0);	810	ev_run (my_loop, 0);
772	... jobs done or somebody called unloop. yeah!	811	... jobs done or somebody called unloop. yeah!
773		812
774	=item ev_unloop (loop, how)	813	=item ev_break (loop, how)
775		814
776	Can be used to make a call to C<ev_loop> return early (but only after it	815	Can be used to make a call to C<ev_run> return early (but only after it
777	has processed all outstanding events). The C<how> argument must be either	816	has processed all outstanding events). The C<how> argument must be either
778	C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or	817	C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or
779	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.	818	C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return.
780		819
781	This "unloop state" will be cleared when entering C<ev_loop> again.	820	This "unloop state" will be cleared when entering C<ev_run> again.
782		821
783	It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls.	822	It is safe to call C<ev_break> from outside any C<ev_run> calls. ##TODO##
784		823
785	=item ev_ref (loop)	824	=item ev_ref (loop)
786		825
787	=item ev_unref (loop)	826	=item ev_unref (loop)
788		827
789	Ref/unref can be used to add or remove a reference count on the event	828	Ref/unref can be used to add or remove a reference count on the event
790	loop: Every watcher keeps one reference, and as long as the reference	829	loop: Every watcher keeps one reference, and as long as the reference
791	count is nonzero, C<ev_loop> will not return on its own.	830	count is nonzero, C<ev_run> will not return on its own.
792		831
793	If you have a watcher you never unregister that should not keep C<ev_loop>	832	This is useful when you have a watcher that you never intend to
794	from returning, call ev_unref() after starting, and ev_ref() before	833	unregister, but that nevertheless should not keep C<ev_run> from
		834	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>
795	stopping it.	835	before stopping it.
796		836
797	As an example, libev itself uses this for its internal signal pipe: It	837	As an example, libev itself uses this for its internal signal pipe: It
798	is not visible to the libev user and should not keep C<ev_loop> from	838	is not visible to the libev user and should not keep C<ev_run> from
799	exiting if no event watchers registered by it are active. It is also an	839	exiting if no event watchers registered by it are active. It is also an
800	excellent way to do this for generic recurring timers or from within	840	excellent way to do this for generic recurring timers or from within
801	third-party libraries. Just remember to I<unref after start> and I<ref	841	third-party libraries. Just remember to I<unref after start> and I<ref
802	before stop> (but only if the watcher wasn't active before, or was active	842	before stop> (but only if the watcher wasn't active before, or was active
803	before, respectively. Note also that libev might stop watchers itself	843	before, respectively. Note also that libev might stop watchers itself
804	(e.g. non-repeating timers) in which case you have to C<ev_ref>	844	(e.g. non-repeating timers) in which case you have to C<ev_ref>
805	in the callback).	845	in the callback).
806		846
807	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	847	Example: Create a signal watcher, but keep it from keeping C<ev_run>
808	running when nothing else is active.	848	running when nothing else is active.
809		849
810	ev_signal exitsig;	850	ev_signal exitsig;
811	ev_signal_init (&exitsig, sig_cb, SIGINT);	851	ev_signal_init (&exitsig, sig_cb, SIGINT);
812	ev_signal_start (loop, &exitsig);	852	ev_signal_start (loop, &exitsig);
…		…
857	usually doesn't make much sense to set it to a lower value than C<0.01>,	897	usually doesn't make much sense to set it to a lower value than C<0.01>,
858	as this approaches the timing granularity of most systems. Note that if	898	as this approaches the timing granularity of most systems. Note that if
859	you do transactions with the outside world and you can't increase the	899	you do transactions with the outside world and you can't increase the
860	parallelity, then this setting will limit your transaction rate (if you	900	parallelity, then this setting will limit your transaction rate (if you
861	need to poll once per transaction and the I/O collect interval is 0.01,	901	need to poll once per transaction and the I/O collect interval is 0.01,
862	then you can't do more than 100 transations per second).	902	then you can't do more than 100 transactions per second).
863		903
864	Setting the I<timeout collect interval> can improve the opportunity for	904	Setting the I<timeout collect interval> can improve the opportunity for
865	saving power, as the program will "bundle" timer callback invocations that	905	saving power, as the program will "bundle" timer callback invocations that
866	are "near" in time together, by delaying some, thus reducing the number of	906	are "near" in time together, by delaying some, thus reducing the number of
867	times the process sleeps and wakes up again. Another useful technique to	907	times the process sleeps and wakes up again. Another useful technique to
…		…
875	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);	915	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);
876		916
877	=item ev_invoke_pending (loop)	917	=item ev_invoke_pending (loop)
878		918
879	This call will simply invoke all pending watchers while resetting their	919	This call will simply invoke all pending watchers while resetting their
880	pending state. Normally, C<ev_loop> does this automatically when required,	920	pending state. Normally, C<ev_run> does this automatically when required,
881	but when overriding the invoke callback this call comes handy.	921	but when overriding the invoke callback this call comes handy. This
		922	function can be invoked from a watcher - this can be useful for example
		923	when you want to do some lengthy calculation and want to pass further
		924	event handling to another thread (you still have to make sure only one
		925	thread executes within C<ev_invoke_pending> or C<ev_run> of course).
882		926
883	=item int ev_pending_count (loop)	927	=item int ev_pending_count (loop)
884		928
885	Returns the number of pending watchers - zero indicates that no watchers	929	Returns the number of pending watchers - zero indicates that no watchers
886	are pending.	930	are pending.
887		931
888	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))	932	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))
889		933
890	This overrides the invoke pending functionality of the loop: Instead of	934	This overrides the invoke pending functionality of the loop: Instead of
891	invoking all pending watchers when there are any, C<ev_loop> will call	935	invoking all pending watchers when there are any, C<ev_run> will call
892	this callback instead. This is useful, for example, when you want to	936	this callback instead. This is useful, for example, when you want to
893	invoke the actual watchers inside another context (another thread etc.).	937	invoke the actual watchers inside another context (another thread etc.).
894		938
895	If you want to reset the callback, use C<ev_invoke_pending> as new	939	If you want to reset the callback, use C<ev_invoke_pending> as new
896	callback.	940	callback.
…		…
899		943
900	Sometimes you want to share the same loop between multiple threads. This	944	Sometimes you want to share the same loop between multiple threads. This
901	can be done relatively simply by putting mutex_lock/unlock calls around	945	can be done relatively simply by putting mutex_lock/unlock calls around
902	each call to a libev function.	946	each call to a libev function.
903		947
904	However, C<ev_loop> can run an indefinite time, so it is not feasible to	948	However, C<ev_run> can run an indefinite time, so it is not feasible
905	wait for it to return. One way around this is to wake up the loop via	949	to wait for it to return. One way around this is to wake up the event
906	C<ev_unloop> and C<av_async_send>, another way is to set these I<release>	950	loop via C<ev_break> and C<av_async_send>, another way is to set these
907	and I<acquire> callbacks on the loop.	951	I<release> and I<acquire> callbacks on the loop.
908		952
909	When set, then C<release> will be called just before the thread is	953	When set, then C<release> will be called just before the thread is
910	suspended waiting for new events, and C<acquire> is called just	954	suspended waiting for new events, and C<acquire> is called just
911	afterwards.	955	afterwards.
912		956
…		…
915		959
916	While event loop modifications are allowed between invocations of	960	While event loop modifications are allowed between invocations of
917	C<release> and C<acquire> (that's their only purpose after all), no	961	C<release> and C<acquire> (that's their only purpose after all), no
918	modifications done will affect the event loop, i.e. adding watchers will	962	modifications done will affect the event loop, i.e. adding watchers will
919	have no effect on the set of file descriptors being watched, or the time	963	have no effect on the set of file descriptors being watched, or the time
920	waited. USe an C<ev_async> watcher to wake up C<ev_loop> when you want it	964	waited. Use an C<ev_async> watcher to wake up C<ev_run> when you want it
921	to take note of any changes you made.	965	to take note of any changes you made.
922		966
923	In theory, threads executing C<ev_loop> will be async-cancel safe between	967	In theory, threads executing C<ev_run> will be async-cancel safe between
924	invocations of C<release> and C<acquire>.	968	invocations of C<release> and C<acquire>.
925		969
926	See also the locking example in the C<THREADS> section later in this	970	See also the locking example in the C<THREADS> section later in this
927	document.	971	document.
928		972
…		…
937	These two functions can be used to associate arbitrary data with a loop,	981	These two functions can be used to associate arbitrary data with a loop,
938	and are intended solely for the C<invoke_pending_cb>, C<release> and	982	and are intended solely for the C<invoke_pending_cb>, C<release> and
939	C<acquire> callbacks described above, but of course can be (ab-)used for	983	C<acquire> callbacks described above, but of course can be (ab-)used for
940	any other purpose as well.	984	any other purpose as well.
941		985
942	=item ev_loop_verify (loop)	986	=item ev_verify (loop)
943		987
944	This function only does something when C<EV_VERIFY> support has been	988	This function only does something when C<EV_VERIFY> support has been
945	compiled in, which is the default for non-minimal builds. It tries to go	989	compiled in, which is the default for non-minimal builds. It tries to go
946	through all internal structures and checks them for validity. If anything	990	through all internal structures and checks them for validity. If anything
947	is found to be inconsistent, it will print an error message to standard	991	is found to be inconsistent, it will print an error message to standard
…		…
958		1002
959	In the following description, uppercase C<TYPE> in names stands for the	1003	In the following description, uppercase C<TYPE> in names stands for the
960	watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer	1004	watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer
961	watchers and C<ev_io_start> for I/O watchers.	1005	watchers and C<ev_io_start> for I/O watchers.
962		1006
963	A watcher is a structure that you create and register to record your	1007	A watcher is an opaque structure that you allocate and register to record
964	interest in some event. For instance, if you want to wait for STDIN to	1008	your interest in some event. To make a concrete example, imagine you want
965	become readable, you would create an C<ev_io> watcher for that:	1009	to wait for STDIN to become readable, you would create an C<ev_io> watcher
		1010	for that:
966		1011
967	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)	1012	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)
968	{	1013	{
969	ev_io_stop (w);	1014	ev_io_stop (w);
970	ev_unloop (loop, EVUNLOOP_ALL);	1015	ev_break (loop, EVBREAK_ALL);
971	}	1016	}
972		1017
973	struct ev_loop *loop = ev_default_loop (0);	1018	struct ev_loop *loop = ev_default_loop (0);
974		1019
975	ev_io stdin_watcher;	1020	ev_io stdin_watcher;
976		1021
977	ev_init (&stdin_watcher, my_cb);	1022	ev_init (&stdin_watcher, my_cb);
978	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	1023	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
979	ev_io_start (loop, &stdin_watcher);	1024	ev_io_start (loop, &stdin_watcher);
980		1025
981	ev_loop (loop, 0);	1026	ev_run (loop, 0);
982		1027
983	As you can see, you are responsible for allocating the memory for your	1028	As you can see, you are responsible for allocating the memory for your
984	watcher structures (and it is I<usually> a bad idea to do this on the	1029	watcher structures (and it is I<usually> a bad idea to do this on the
985	stack).	1030	stack).
986		1031
987	Each watcher has an associated watcher structure (called C<struct ev_TYPE>	1032	Each watcher has an associated watcher structure (called C<struct ev_TYPE>
988	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).	1033	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).
989		1034
990	Each watcher structure must be initialised by a call to C<ev_init	1035	Each watcher structure must be initialised by a call to C<ev_init (watcher
991	(watcher *, callback)>, which expects a callback to be provided. This	1036	*, callback)>, which expects a callback to be provided. This callback is
992	callback gets invoked each time the event occurs (or, in the case of I/O	1037	invoked each time the event occurs (or, in the case of I/O watchers, each
993	watchers, each time the event loop detects that the file descriptor given	1038	time the event loop detects that the file descriptor given is readable
994	is readable and/or writable).	1039	and/or writable).
995		1040
996	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>	1041	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>
997	macro to configure it, with arguments specific to the watcher type. There	1042	macro to configure it, with arguments specific to the watcher type. There
998	is also a macro to combine initialisation and setting in one call: C<<	1043	is also a macro to combine initialisation and setting in one call: C<<
999	ev_TYPE_init (watcher *, callback, ...) >>.	1044	ev_TYPE_init (watcher *, callback, ...) >>.
…		…
1022	=item C<EV_WRITE>	1067	=item C<EV_WRITE>
1023		1068
1024	The file descriptor in the C<ev_io> watcher has become readable and/or	1069	The file descriptor in the C<ev_io> watcher has become readable and/or
1025	writable.	1070	writable.
1026		1071
1027	=item C<EV_TIMEOUT>	1072	=item C<EV_TIMER>
1028		1073
1029	The C<ev_timer> watcher has timed out.	1074	The C<ev_timer> watcher has timed out.
1030		1075
1031	=item C<EV_PERIODIC>	1076	=item C<EV_PERIODIC>
1032		1077
…		…
1050		1095
1051	=item C<EV_PREPARE>	1096	=item C<EV_PREPARE>
1052		1097
1053	=item C<EV_CHECK>	1098	=item C<EV_CHECK>
1054		1099
1055	All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts	1100	All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts
1056	to gather new events, and all C<ev_check> watchers are invoked just after	1101	to gather new events, and all C<ev_check> watchers are invoked just after
1057	C<ev_loop> has gathered them, but before it invokes any callbacks for any	1102	C<ev_run> has gathered them, but before it invokes any callbacks for any
1058	received events. Callbacks of both watcher types can start and stop as	1103	received events. Callbacks of both watcher types can start and stop as
1059	many watchers as they want, and all of them will be taken into account	1104	many watchers as they want, and all of them will be taken into account
1060	(for example, a C<ev_prepare> watcher might start an idle watcher to keep	1105	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
1061	C<ev_loop> from blocking).	1106	C<ev_run> from blocking).
1062		1107
1063	=item C<EV_EMBED>	1108	=item C<EV_EMBED>
1064		1109
1065	The embedded event loop specified in the C<ev_embed> watcher needs attention.	1110	The embedded event loop specified in the C<ev_embed> watcher needs attention.
1066		1111
…		…
1097	programs, though, as the fd could already be closed and reused for another	1142	programs, though, as the fd could already be closed and reused for another
1098	thing, so beware.	1143	thing, so beware.
1099		1144
1100	=back	1145	=back
1101		1146
		1147	=head2 WATCHER STATES
		1148
		1149	There are various watcher states mentioned throughout this manual -
		1150	active, pending and so on. In this section these states and the rules to
		1151	transition between them will be described in more detail - and while these
		1152	rules might look complicated, they usually do "the right thing".
		1153
		1154	=over 4
		1155
		1156	=item initialiased
		1157
		1158	Before a watcher can be registered with the event looop it has to be
		1159	initialised. This can be done with a call to C<ev_TYPE_init>, or calls to
		1160	C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function.
		1161
		1162	In this state it is simply some block of memory that is suitable for use
		1163	in an event loop. It can be moved around, freed, reused etc. at will.
		1164
		1165	=item started/running/active
		1166
		1167	Once a watcher has been started with a call to C<ev_TYPE_start> it becomes
		1168	property of the event loop, and is actively waiting for events. While in
		1169	this state it cannot be accessed (except in a few documented ways), moved,
		1170	freed or anything else - the only legal thing is to keep a pointer to it,
		1171	and call libev functions on it that are documented to work on active watchers.
		1172
		1173	=item pending
		1174
		1175	If a watcher is active and libev determines that an event it is interested
		1176	in has occurred (such as a timer expiring), it will become pending. It will
		1177	stay in this pending state until either it is stopped or its callback is
		1178	about to be invoked, so it is not normally pending inside the watcher
		1179	callback.
		1180
		1181	The watcher might or might not be active while it is pending (for example,
		1182	an expired non-repeating timer can be pending but no longer active). If it
		1183	is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>),
		1184	but it is still property of the event loop at this time, so cannot be
		1185	moved, freed or reused. And if it is active the rules described in the
		1186	previous item still apply.
		1187
		1188	It is also possible to feed an event on a watcher that is not active (e.g.
		1189	via C<ev_feed_event>), in which case it becomes pending without being
		1190	active.
		1191
		1192	=item stopped
		1193
		1194	A watcher can be stopped implicitly by libev (in which case it might still
		1195	be pending), or explicitly by calling its C<ev_TYPE_stop> function. The
		1196	latter will clear any pending state the watcher might be in, regardless
		1197	of whether it was active or not, so stopping a watcher explicitly before
		1198	freeing it is often a good idea.
		1199
		1200	While stopped (and not pending) the watcher is essentially in the
		1201	initialised state, that is it can be reused, moved, modified in any way
		1202	you wish.
		1203
		1204	=back
		1205
1102	=head2 GENERIC WATCHER FUNCTIONS	1206	=head2 GENERIC WATCHER FUNCTIONS
1103		1207
1104	=over 4	1208	=over 4
1105		1209
1106	=item C<ev_init> (ev_TYPE *watcher, callback)	1210	=item C<ev_init> (ev_TYPE *watcher, callback)
…		…
1122		1226
1123	ev_io w;	1227	ev_io w;
1124	ev_init (&w, my_cb);	1228	ev_init (&w, my_cb);
1125	ev_io_set (&w, STDIN_FILENO, EV_READ);	1229	ev_io_set (&w, STDIN_FILENO, EV_READ);
1126		1230
1127	=item C<ev_TYPE_set> (ev_TYPE *, [args])	1231	=item C<ev_TYPE_set> (ev_TYPE *watcher, [args])
1128		1232
1129	This macro initialises the type-specific parts of a watcher. You need to	1233	This macro initialises the type-specific parts of a watcher. You need to
1130	call C<ev_init> at least once before you call this macro, but you can	1234	call C<ev_init> at least once before you call this macro, but you can
1131	call C<ev_TYPE_set> any number of times. You must not, however, call this	1235	call C<ev_TYPE_set> any number of times. You must not, however, call this
1132	macro on a watcher that is active (it can be pending, however, which is a	1236	macro on a watcher that is active (it can be pending, however, which is a
…		…
1145		1249
1146	Example: Initialise and set an C<ev_io> watcher in one step.	1250	Example: Initialise and set an C<ev_io> watcher in one step.
1147		1251
1148	ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ);	1252	ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ);
1149		1253
1150	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)	1254	=item C<ev_TYPE_start> (loop, ev_TYPE *watcher)
1151		1255
1152	Starts (activates) the given watcher. Only active watchers will receive	1256	Starts (activates) the given watcher. Only active watchers will receive
1153	events. If the watcher is already active nothing will happen.	1257	events. If the watcher is already active nothing will happen.
1154		1258
1155	Example: Start the C<ev_io> watcher that is being abused as example in this	1259	Example: Start the C<ev_io> watcher that is being abused as example in this
1156	whole section.	1260	whole section.
1157		1261
1158	ev_io_start (EV_DEFAULT_UC, &w);	1262	ev_io_start (EV_DEFAULT_UC, &w);
1159		1263
1160	=item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher)	1264	=item C<ev_TYPE_stop> (loop, ev_TYPE *watcher)
1161		1265
1162	Stops the given watcher if active, and clears the pending status (whether	1266	Stops the given watcher if active, and clears the pending status (whether
1163	the watcher was active or not).	1267	the watcher was active or not).
1164		1268
1165	It is possible that stopped watchers are pending - for example,	1269	It is possible that stopped watchers are pending - for example,
…		…
1190	=item ev_cb_set (ev_TYPE *watcher, callback)	1294	=item ev_cb_set (ev_TYPE *watcher, callback)
1191		1295
1192	Change the callback. You can change the callback at virtually any time	1296	Change the callback. You can change the callback at virtually any time
1193	(modulo threads).	1297	(modulo threads).
1194		1298
1195	=item ev_set_priority (ev_TYPE *watcher, priority)	1299	=item ev_set_priority (ev_TYPE *watcher, int priority)
1196		1300
1197	=item int ev_priority (ev_TYPE *watcher)	1301	=item int ev_priority (ev_TYPE *watcher)
1198		1302
1199	Set and query the priority of the watcher. The priority is a small	1303	Set and query the priority of the watcher. The priority is a small
1200	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>	1304	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>
…		…
1231	returns its C<revents> bitset (as if its callback was invoked). If the	1335	returns its C<revents> bitset (as if its callback was invoked). If the
1232	watcher isn't pending it does nothing and returns C<0>.	1336	watcher isn't pending it does nothing and returns C<0>.
1233		1337
1234	Sometimes it can be useful to "poll" a watcher instead of waiting for its	1338	Sometimes it can be useful to "poll" a watcher instead of waiting for its
1235	callback to be invoked, which can be accomplished with this function.	1339	callback to be invoked, which can be accomplished with this function.
		1340
		1341	=item ev_feed_event (loop, ev_TYPE *watcher, int revents)
		1342
		1343	Feeds the given event set into the event loop, as if the specified event
		1344	had happened for the specified watcher (which must be a pointer to an
		1345	initialised but not necessarily started event watcher). Obviously you must
		1346	not free the watcher as long as it has pending events.
		1347
		1348	Stopping the watcher, letting libev invoke it, or calling
		1349	C<ev_clear_pending> will clear the pending event, even if the watcher was
		1350	not started in the first place.
		1351
		1352	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related
		1353	functions that do not need a watcher.
1236		1354
1237	=back	1355	=back
1238		1356
1239		1357
1240	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	1358	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
1351		1469
1352	For example, to emulate how many other event libraries handle priorities,	1470	For example, to emulate how many other event libraries handle priorities,
1353	you can associate an C<ev_idle> watcher to each such watcher, and in	1471	you can associate an C<ev_idle> watcher to each such watcher, and in
1354	the normal watcher callback, you just start the idle watcher. The real	1472	the normal watcher callback, you just start the idle watcher. The real
1355	processing is done in the idle watcher callback. This causes libev to	1473	processing is done in the idle watcher callback. This causes libev to
1356	continously poll and process kernel event data for the watcher, but when	1474	continuously poll and process kernel event data for the watcher, but when
1357	the lock-out case is known to be rare (which in turn is rare :), this is	1475	the lock-out case is known to be rare (which in turn is rare :), this is
1358	workable.	1476	workable.
1359		1477
1360	Usually, however, the lock-out model implemented that way will perform	1478	Usually, however, the lock-out model implemented that way will perform
1361	miserably under the type of load it was designed to handle. In that case,	1479	miserably under the type of load it was designed to handle. In that case,
…		…
1375	{	1493	{
1376	// stop the I/O watcher, we received the event, but	1494	// stop the I/O watcher, we received the event, but
1377	// are not yet ready to handle it.	1495	// are not yet ready to handle it.
1378	ev_io_stop (EV_A_ w);	1496	ev_io_stop (EV_A_ w);
1379		1497
1380	// start the idle watcher to ahndle the actual event.	1498	// start the idle watcher to handle the actual event.
1381	// it will not be executed as long as other watchers	1499	// it will not be executed as long as other watchers
1382	// with the default priority are receiving events.	1500	// with the default priority are receiving events.
1383	ev_idle_start (EV_A_ &idle);	1501	ev_idle_start (EV_A_ &idle);
1384	}	1502	}
1385		1503
…		…
1439		1557
1440	If you cannot use non-blocking mode, then force the use of a	1558	If you cannot use non-blocking mode, then force the use of a
1441	known-to-be-good backend (at the time of this writing, this includes only	1559	known-to-be-good backend (at the time of this writing, this includes only
1442	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file	1560	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file
1443	descriptors for which non-blocking operation makes no sense (such as	1561	descriptors for which non-blocking operation makes no sense (such as
1444	files) - libev doesn't guarentee any specific behaviour in that case.	1562	files) - libev doesn't guarantee any specific behaviour in that case.
1445		1563
1446	Another thing you have to watch out for is that it is quite easy to	1564	Another thing you have to watch out for is that it is quite easy to
1447	receive "spurious" readiness notifications, that is your callback might	1565	receive "spurious" readiness notifications, that is your callback might
1448	be called with C<EV_READ> but a subsequent C<read>(2) will actually block	1566	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
1449	because there is no data. Not only are some backends known to create a	1567	because there is no data. Not only are some backends known to create a
…		…
1514		1632
1515	So when you encounter spurious, unexplained daemon exits, make sure you	1633	So when you encounter spurious, unexplained daemon exits, make sure you
1516	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon	1634	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon
1517	somewhere, as that would have given you a big clue).	1635	somewhere, as that would have given you a big clue).
1518		1636
		1637	=head3 The special problem of accept()ing when you can't
		1638
		1639	Many implementations of the POSIX C<accept> function (for example,
		1640	found in post-2004 Linux) have the peculiar behaviour of not removing a
		1641	connection from the pending queue in all error cases.
		1642
		1643	For example, larger servers often run out of file descriptors (because
		1644	of resource limits), causing C<accept> to fail with C<ENFILE> but not
		1645	rejecting the connection, leading to libev signalling readiness on
		1646	the next iteration again (the connection still exists after all), and
		1647	typically causing the program to loop at 100% CPU usage.
		1648
		1649	Unfortunately, the set of errors that cause this issue differs between
		1650	operating systems, there is usually little the app can do to remedy the
		1651	situation, and no known thread-safe method of removing the connection to
		1652	cope with overload is known (to me).
		1653
		1654	One of the easiest ways to handle this situation is to just ignore it
		1655	- when the program encounters an overload, it will just loop until the
		1656	situation is over. While this is a form of busy waiting, no OS offers an
		1657	event-based way to handle this situation, so it's the best one can do.
		1658
		1659	A better way to handle the situation is to log any errors other than
		1660	C<EAGAIN> and C<EWOULDBLOCK>, making sure not to flood the log with such
		1661	messages, and continue as usual, which at least gives the user an idea of
		1662	what could be wrong ("raise the ulimit!"). For extra points one could stop
		1663	the C<ev_io> watcher on the listening fd "for a while", which reduces CPU
		1664	usage.
		1665
		1666	If your program is single-threaded, then you could also keep a dummy file
		1667	descriptor for overload situations (e.g. by opening F</dev/null>), and
		1668	when you run into C<ENFILE> or C<EMFILE>, close it, run C<accept>,
		1669	close that fd, and create a new dummy fd. This will gracefully refuse
		1670	clients under typical overload conditions.
		1671
		1672	The last way to handle it is to simply log the error and C<exit>, as
		1673	is often done with C<malloc> failures, but this results in an easy
		1674	opportunity for a DoS attack.
1519		1675
1520	=head3 Watcher-Specific Functions	1676	=head3 Watcher-Specific Functions
1521		1677
1522	=over 4	1678	=over 4
1523		1679
…		…
1555	...	1711	...
1556	struct ev_loop *loop = ev_default_init (0);	1712	struct ev_loop *loop = ev_default_init (0);
1557	ev_io stdin_readable;	1713	ev_io stdin_readable;
1558	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1714	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1559	ev_io_start (loop, &stdin_readable);	1715	ev_io_start (loop, &stdin_readable);
1560	ev_loop (loop, 0);	1716	ev_run (loop, 0);
1561		1717
1562		1718
1563	=head2 C<ev_timer> - relative and optionally repeating timeouts	1719	=head2 C<ev_timer> - relative and optionally repeating timeouts
1564		1720
1565	Timer watchers are simple relative timers that generate an event after a	1721	Timer watchers are simple relative timers that generate an event after a
…		…
1574	The callback is guaranteed to be invoked only I<after> its timeout has	1730	The callback is guaranteed to be invoked only I<after> its timeout has
1575	passed (not I<at>, so on systems with very low-resolution clocks this	1731	passed (not I<at>, so on systems with very low-resolution clocks this
1576	might introduce a small delay). If multiple timers become ready during the	1732	might introduce a small delay). If multiple timers become ready during the
1577	same loop iteration then the ones with earlier time-out values are invoked	1733	same loop iteration then the ones with earlier time-out values are invoked
1578	before ones of the same priority with later time-out values (but this is	1734	before ones of the same priority with later time-out values (but this is
1579	no longer true when a callback calls C<ev_loop> recursively).	1735	no longer true when a callback calls C<ev_run> recursively).
1580		1736
1581	=head3 Be smart about timeouts	1737	=head3 Be smart about timeouts
1582		1738
1583	Many real-world problems involve some kind of timeout, usually for error	1739	Many real-world problems involve some kind of timeout, usually for error
1584	recovery. A typical example is an HTTP request - if the other side hangs,	1740	recovery. A typical example is an HTTP request - if the other side hangs,
…		…
1670	ev_tstamp timeout = last_activity + 60.;	1826	ev_tstamp timeout = last_activity + 60.;
1671		1827
1672	// if last_activity + 60. is older than now, we did time out	1828	// if last_activity + 60. is older than now, we did time out
1673	if (timeout < now)	1829	if (timeout < now)
1674	{	1830	{
1675	// timeout occured, take action	1831	// timeout occurred, take action
1676	}	1832	}
1677	else	1833	else
1678	{	1834	{
1679	// callback was invoked, but there was some activity, re-arm	1835	// callback was invoked, but there was some activity, re-arm
1680	// the watcher to fire in last_activity + 60, which is	1836	// the watcher to fire in last_activity + 60, which is
…		…
1702	to the current time (meaning we just have some activity :), then call the	1858	to the current time (meaning we just have some activity :), then call the
1703	callback, which will "do the right thing" and start the timer:	1859	callback, which will "do the right thing" and start the timer:
1704		1860
1705	ev_init (timer, callback);	1861	ev_init (timer, callback);
1706	last_activity = ev_now (loop);	1862	last_activity = ev_now (loop);
1707	callback (loop, timer, EV_TIMEOUT);	1863	callback (loop, timer, EV_TIMER);
1708		1864
1709	And when there is some activity, simply store the current time in	1865	And when there is some activity, simply store the current time in
1710	C<last_activity>, no libev calls at all:	1866	C<last_activity>, no libev calls at all:
1711		1867
1712	last_actiivty = ev_now (loop);	1868	last_activity = ev_now (loop);
1713		1869
1714	This technique is slightly more complex, but in most cases where the	1870	This technique is slightly more complex, but in most cases where the
1715	time-out is unlikely to be triggered, much more efficient.	1871	time-out is unlikely to be triggered, much more efficient.
1716		1872
1717	Changing the timeout is trivial as well (if it isn't hard-coded in the	1873	Changing the timeout is trivial as well (if it isn't hard-coded in the
…		…
1755		1911
1756	=head3 The special problem of time updates	1912	=head3 The special problem of time updates
1757		1913
1758	Establishing the current time is a costly operation (it usually takes at	1914	Establishing the current time is a costly operation (it usually takes at
1759	least two system calls): EV therefore updates its idea of the current	1915	least two system calls): EV therefore updates its idea of the current
1760	time only before and after C<ev_loop> collects new events, which causes a	1916	time only before and after C<ev_run> collects new events, which causes a
1761	growing difference between C<ev_now ()> and C<ev_time ()> when handling	1917	growing difference between C<ev_now ()> and C<ev_time ()> when handling
1762	lots of events in one iteration.	1918	lots of events in one iteration.
1763		1919
1764	The relative timeouts are calculated relative to the C<ev_now ()>	1920	The relative timeouts are calculated relative to the C<ev_now ()>
1765	time. This is usually the right thing as this timestamp refers to the time	1921	time. This is usually the right thing as this timestamp refers to the time
…		…
1836	C<repeat> value), or reset the running timer to the C<repeat> value.	1992	C<repeat> value), or reset the running timer to the C<repeat> value.
1837		1993
1838	This sounds a bit complicated, see L<Be smart about timeouts>, above, for a	1994	This sounds a bit complicated, see L<Be smart about timeouts>, above, for a
1839	usage example.	1995	usage example.
1840		1996
1841	=item ev_timer_remaining (loop, ev_timer *)	1997	=item ev_tstamp ev_timer_remaining (loop, ev_timer *)
1842		1998
1843	Returns the remaining time until a timer fires. If the timer is active,	1999	Returns the remaining time until a timer fires. If the timer is active,
1844	then this time is relative to the current event loop time, otherwise it's	2000	then this time is relative to the current event loop time, otherwise it's
1845	the timeout value currently configured.	2001	the timeout value currently configured.
1846		2002
1847	That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns	2003	That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns
1848	C<5>. When the timer is started and one second passes, C<ev_timer_remain>	2004	C<5>. When the timer is started and one second passes, C<ev_timer_remaining>
1849	will return C<4>. When the timer expires and is restarted, it will return	2005	will return C<4>. When the timer expires and is restarted, it will return
1850	roughly C<7> (likely slightly less as callback invocation takes some time,	2006	roughly C<7> (likely slightly less as callback invocation takes some time,
1851	too), and so on.	2007	too), and so on.
1852		2008
1853	=item ev_tstamp repeat [read-write]	2009	=item ev_tstamp repeat [read-write]
…		…
1882	}	2038	}
1883		2039
1884	ev_timer mytimer;	2040	ev_timer mytimer;
1885	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	2041	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1886	ev_timer_again (&mytimer); /* start timer */	2042	ev_timer_again (&mytimer); /* start timer */
1887	ev_loop (loop, 0);	2043	ev_run (loop, 0);
1888		2044
1889	// and in some piece of code that gets executed on any "activity":	2045	// and in some piece of code that gets executed on any "activity":
1890	// reset the timeout to start ticking again at 10 seconds	2046	// reset the timeout to start ticking again at 10 seconds
1891	ev_timer_again (&mytimer);	2047	ev_timer_again (&mytimer);
1892		2048
…		…
1918		2074
1919	As with timers, the callback is guaranteed to be invoked only when the	2075	As with timers, the callback is guaranteed to be invoked only when the
1920	point in time where it is supposed to trigger has passed. If multiple	2076	point in time where it is supposed to trigger has passed. If multiple
1921	timers become ready during the same loop iteration then the ones with	2077	timers become ready during the same loop iteration then the ones with
1922	earlier time-out values are invoked before ones with later time-out values	2078	earlier time-out values are invoked before ones with later time-out values
1923	(but this is no longer true when a callback calls C<ev_loop> recursively).	2079	(but this is no longer true when a callback calls C<ev_run> recursively).
1924		2080
1925	=head3 Watcher-Specific Functions and Data Members	2081	=head3 Watcher-Specific Functions and Data Members
1926		2082
1927	=over 4	2083	=over 4
1928		2084
…		…
2056	Example: Call a callback every hour, or, more precisely, whenever the	2212	Example: Call a callback every hour, or, more precisely, whenever the
2057	system time is divisible by 3600. The callback invocation times have	2213	system time is divisible by 3600. The callback invocation times have
2058	potentially a lot of jitter, but good long-term stability.	2214	potentially a lot of jitter, but good long-term stability.
2059		2215
2060	static void	2216	static void
2061	clock_cb (struct ev_loop *loop, ev_io *w, int revents)	2217	clock_cb (struct ev_loop *loop, ev_periodic *w, int revents)
2062	{	2218	{
2063	... its now a full hour (UTC, or TAI or whatever your clock follows)	2219	... its now a full hour (UTC, or TAI or whatever your clock follows)
2064	}	2220	}
2065		2221
2066	ev_periodic hourly_tick;	2222	ev_periodic hourly_tick;
…		…
2107		2263
2108	When the first watcher gets started will libev actually register something	2264	When the first watcher gets started will libev actually register something
2109	with the kernel (thus it coexists with your own signal handlers as long as	2265	with the kernel (thus it coexists with your own signal handlers as long as
2110	you don't register any with libev for the same signal).	2266	you don't register any with libev for the same signal).
2111		2267
2112	Both the signal mask state (C<sigprocmask>) and the signal handler state
2113	(C<sigaction>) are unspecified after starting a signal watcher (and after
2114	sotpping it again), that is, libev might or might not block the signal,
2115	and might or might not set or restore the installed signal handler.
2116
2117	If possible and supported, libev will install its handlers with	2268	If possible and supported, libev will install its handlers with
2118	C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should	2269	C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should
2119	not be unduly interrupted. If you have a problem with system calls getting	2270	not be unduly interrupted. If you have a problem with system calls getting
2120	interrupted by signals you can block all signals in an C<ev_check> watcher	2271	interrupted by signals you can block all signals in an C<ev_check> watcher
2121	and unblock them in an C<ev_prepare> watcher.	2272	and unblock them in an C<ev_prepare> watcher.
2122		2273
		2274	=head3 The special problem of inheritance over fork/execve/pthread_create
		2275
		2276	Both the signal mask (C<sigprocmask>) and the signal disposition
		2277	(C<sigaction>) are unspecified after starting a signal watcher (and after
		2278	stopping it again), that is, libev might or might not block the signal,
		2279	and might or might not set or restore the installed signal handler.
		2280
		2281	While this does not matter for the signal disposition (libev never
		2282	sets signals to C<SIG_IGN>, so handlers will be reset to C<SIG_DFL> on
		2283	C<execve>), this matters for the signal mask: many programs do not expect
		2284	certain signals to be blocked.
		2285
		2286	This means that before calling C<exec> (from the child) you should reset
		2287	the signal mask to whatever "default" you expect (all clear is a good
		2288	choice usually).
		2289
		2290	The simplest way to ensure that the signal mask is reset in the child is
		2291	to install a fork handler with C<pthread_atfork> that resets it. That will
		2292	catch fork calls done by libraries (such as the libc) as well.
		2293
		2294	In current versions of libev, the signal will not be blocked indefinitely
		2295	unless you use the C<signalfd> API (C<EV_SIGNALFD>). While this reduces
		2296	the window of opportunity for problems, it will not go away, as libev
		2297	I<has> to modify the signal mask, at least temporarily.
		2298
		2299	So I can't stress this enough: I<If you do not reset your signal mask when
		2300	you expect it to be empty, you have a race condition in your code>. This
		2301	is not a libev-specific thing, this is true for most event libraries.
		2302
2123	=head3 Watcher-Specific Functions and Data Members	2303	=head3 Watcher-Specific Functions and Data Members
2124		2304
2125	=over 4	2305	=over 4
2126		2306
2127	=item ev_signal_init (ev_signal *, callback, int signum)	2307	=item ev_signal_init (ev_signal *, callback, int signum)
…		…
2142	Example: Try to exit cleanly on SIGINT.	2322	Example: Try to exit cleanly on SIGINT.
2143		2323
2144	static void	2324	static void
2145	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)	2325	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)
2146	{	2326	{
2147	ev_unloop (loop, EVUNLOOP_ALL);	2327	ev_break (loop, EVBREAK_ALL);
2148	}	2328	}
2149		2329
2150	ev_signal signal_watcher;	2330	ev_signal signal_watcher;
2151	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	2331	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
2152	ev_signal_start (loop, &signal_watcher);	2332	ev_signal_start (loop, &signal_watcher);
…		…
2538		2718
2539	Prepare and check watchers are usually (but not always) used in pairs:	2719	Prepare and check watchers are usually (but not always) used in pairs:
2540	prepare watchers get invoked before the process blocks and check watchers	2720	prepare watchers get invoked before the process blocks and check watchers
2541	afterwards.	2721	afterwards.
2542		2722
2543	You I<must not> call C<ev_loop> or similar functions that enter	2723	You I<must not> call C<ev_run> or similar functions that enter
2544	the current event loop from either C<ev_prepare> or C<ev_check>	2724	the current event loop from either C<ev_prepare> or C<ev_check>
2545	watchers. Other loops than the current one are fine, however. The	2725	watchers. Other loops than the current one are fine, however. The
2546	rationale behind this is that you do not need to check for recursion in	2726	rationale behind this is that you do not need to check for recursion in
2547	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,	2727	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,
2548	C<ev_check> so if you have one watcher of each kind they will always be	2728	C<ev_check> so if you have one watcher of each kind they will always be
…		…
2716		2896
2717	if (timeout >= 0)	2897	if (timeout >= 0)
2718	// create/start timer	2898	// create/start timer
2719		2899
2720	// poll	2900	// poll
2721	ev_loop (EV_A_ 0);	2901	ev_run (EV_A_ 0);
2722		2902
2723	// stop timer again	2903	// stop timer again
2724	if (timeout >= 0)	2904	if (timeout >= 0)
2725	ev_timer_stop (EV_A_ &to);	2905	ev_timer_stop (EV_A_ &to);
2726		2906
…		…
2804	if you do not want that, you need to temporarily stop the embed watcher).	2984	if you do not want that, you need to temporarily stop the embed watcher).
2805		2985
2806	=item ev_embed_sweep (loop, ev_embed *)	2986	=item ev_embed_sweep (loop, ev_embed *)
2807		2987
2808	Make a single, non-blocking sweep over the embedded loop. This works	2988	Make a single, non-blocking sweep over the embedded loop. This works
2809	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	2989	similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most
2810	appropriate way for embedded loops.	2990	appropriate way for embedded loops.
2811		2991
2812	=item struct ev_loop *other [read-only]	2992	=item struct ev_loop *other [read-only]
2813		2993
2814	The embedded event loop.	2994	The embedded event loop.
…		…
2874	C<ev_default_fork> cheats and calls it in the wrong process, the fork	3054	C<ev_default_fork> cheats and calls it in the wrong process, the fork
2875	handlers will be invoked, too, of course.	3055	handlers will be invoked, too, of course.
2876		3056
2877	=head3 The special problem of life after fork - how is it possible?	3057	=head3 The special problem of life after fork - how is it possible?
2878		3058
2879	Most uses of C<fork()> consist of forking, then some simple calls to ste	3059	Most uses of C<fork()> consist of forking, then some simple calls to set
2880	up/change the process environment, followed by a call to C<exec()>. This	3060	up/change the process environment, followed by a call to C<exec()>. This
2881	sequence should be handled by libev without any problems.	3061	sequence should be handled by libev without any problems.
2882		3062
2883	This changes when the application actually wants to do event handling	3063	This changes when the application actually wants to do event handling
2884	in the child, or both parent in child, in effect "continuing" after the	3064	in the child, or both parent in child, in effect "continuing" after the
…		…
2900	disadvantage of having to use multiple event loops (which do not support	3080	disadvantage of having to use multiple event loops (which do not support
2901	signal watchers).	3081	signal watchers).
2902		3082
2903	When this is not possible, or you want to use the default loop for	3083	When this is not possible, or you want to use the default loop for
2904	other reasons, then in the process that wants to start "fresh", call	3084	other reasons, then in the process that wants to start "fresh", call
2905	C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying	3085	C<ev_loop_destroy (EV_DEFAULT)> followed by C<ev_default_loop (...)>.
2906	the default loop will "orphan" (not stop) all registered watchers, so you	3086	Destroying the default loop will "orphan" (not stop) all registered
2907	have to be careful not to execute code that modifies those watchers. Note	3087	watchers, so you have to be careful not to execute code that modifies
2908	also that in that case, you have to re-register any signal watchers.	3088	those watchers. Note also that in that case, you have to re-register any
		3089	signal watchers.
2909		3090
2910	=head3 Watcher-Specific Functions and Data Members	3091	=head3 Watcher-Specific Functions and Data Members
2911		3092
2912	=over 4	3093	=over 4
2913		3094
…		…
2918	believe me.	3099	believe me.
2919		3100
2920	=back	3101	=back
2921		3102
2922		3103
2923	=head2 C<ev_async> - how to wake up another event loop	3104	=head2 C<ev_async> - how to wake up an event loop
2924		3105
2925	In general, you cannot use an C<ev_loop> from multiple threads or other	3106	In general, you cannot use an C<ev_run> from multiple threads or other
2926	asynchronous sources such as signal handlers (as opposed to multiple event	3107	asynchronous sources such as signal handlers (as opposed to multiple event
2927	loops - those are of course safe to use in different threads).	3108	loops - those are of course safe to use in different threads).
2928		3109
2929	Sometimes, however, you need to wake up another event loop you do not	3110	Sometimes, however, you need to wake up an event loop you do not control,
2930	control, for example because it belongs to another thread. This is what	3111	for example because it belongs to another thread. This is what C<ev_async>
2931	C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you	3112	watchers do: as long as the C<ev_async> watcher is active, you can signal
2932	can signal it by calling C<ev_async_send>, which is thread- and signal	3113	it by calling C<ev_async_send>, which is thread- and signal safe.
2933	safe.
2934		3114
2935	This functionality is very similar to C<ev_signal> watchers, as signals,	3115	This functionality is very similar to C<ev_signal> watchers, as signals,
2936	too, are asynchronous in nature, and signals, too, will be compressed	3116	too, are asynchronous in nature, and signals, too, will be compressed
2937	(i.e. the number of callback invocations may be less than the number of	3117	(i.e. the number of callback invocations may be less than the number of
2938	C<ev_async_sent> calls).	3118	C<ev_async_sent> calls).
…		…
2943	=head3 Queueing	3123	=head3 Queueing
2944		3124
2945	C<ev_async> does not support queueing of data in any way. The reason	3125	C<ev_async> does not support queueing of data in any way. The reason
2946	is that the author does not know of a simple (or any) algorithm for a	3126	is that the author does not know of a simple (or any) algorithm for a
2947	multiple-writer-single-reader queue that works in all cases and doesn't	3127	multiple-writer-single-reader queue that works in all cases and doesn't
2948	need elaborate support such as pthreads.	3128	need elaborate support such as pthreads or unportable memory access
		3129	semantics.
2949		3130
2950	That means that if you want to queue data, you have to provide your own	3131	That means that if you want to queue data, you have to provide your own
2951	queue. But at least I can tell you how to implement locking around your	3132	queue. But at least I can tell you how to implement locking around your
2952	queue:	3133	queue:
2953		3134
…		…
3092		3273
3093	If C<timeout> is less than 0, then no timeout watcher will be	3274	If C<timeout> is less than 0, then no timeout watcher will be
3094	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and	3275	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and
3095	repeat = 0) will be started. C<0> is a valid timeout.	3276	repeat = 0) will be started. C<0> is a valid timeout.
3096		3277
3097	The callback has the type C<void (*cb)(int revents, void *arg)> and gets	3278	The callback has the type C<void (*cb)(int revents, void *arg)> and is
3098	passed an C<revents> set like normal event callbacks (a combination of	3279	passed an C<revents> set like normal event callbacks (a combination of
3099	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>	3280	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMER>) and the C<arg>
3100	value passed to C<ev_once>. Note that it is possible to receive I<both>	3281	value passed to C<ev_once>. Note that it is possible to receive I<both>
3101	a timeout and an io event at the same time - you probably should give io	3282	a timeout and an io event at the same time - you probably should give io
3102	events precedence.	3283	events precedence.
3103		3284
3104	Example: wait up to ten seconds for data to appear on STDIN_FILENO.	3285	Example: wait up to ten seconds for data to appear on STDIN_FILENO.
3105		3286
3106	static void stdin_ready (int revents, void *arg)	3287	static void stdin_ready (int revents, void *arg)
3107	{	3288	{
3108	if (revents & EV_READ)	3289	if (revents & EV_READ)
3109	/* stdin might have data for us, joy! */;	3290	/* stdin might have data for us, joy! */;
3110	else if (revents & EV_TIMEOUT)	3291	else if (revents & EV_TIMER)
3111	/* doh, nothing entered */;	3292	/* doh, nothing entered */;
3112	}	3293	}
3113		3294
3114	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	3295	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
3115		3296
3116	=item ev_feed_event (struct ev_loop *, watcher *, int revents)
3117
3118	Feeds the given event set into the event loop, as if the specified event
3119	had happened for the specified watcher (which must be a pointer to an
3120	initialised but not necessarily started event watcher).
3121
3122	=item ev_feed_fd_event (struct ev_loop *, int fd, int revents)	3297	=item ev_feed_fd_event (loop, int fd, int revents)
3123		3298
3124	Feed an event on the given fd, as if a file descriptor backend detected	3299	Feed an event on the given fd, as if a file descriptor backend detected
3125	the given events it.	3300	the given events it.
3126		3301
3127	=item ev_feed_signal_event (struct ev_loop *loop, int signum)	3302	=item ev_feed_signal_event (loop, int signum)
3128		3303
3129	Feed an event as if the given signal occurred (C<loop> must be the default	3304	Feed an event as if the given signal occurred (C<loop> must be the default
3130	loop!).	3305	loop!).
3131		3306
3132	=back	3307	=back
…		…
3212		3387
3213	=over 4	3388	=over 4
3214		3389
3215	=item ev::TYPE::TYPE ()	3390	=item ev::TYPE::TYPE ()
3216		3391
3217	=item ev::TYPE::TYPE (struct ev_loop *)	3392	=item ev::TYPE::TYPE (loop)
3218		3393
3219	=item ev::TYPE::~TYPE	3394	=item ev::TYPE::~TYPE
3220		3395
3221	The constructor (optionally) takes an event loop to associate the watcher	3396	The constructor (optionally) takes an event loop to associate the watcher
3222	with. If it is omitted, it will use C<EV_DEFAULT>.	3397	with. If it is omitted, it will use C<EV_DEFAULT>.
…		…
3255	myclass obj;	3430	myclass obj;
3256	ev::io iow;	3431	ev::io iow;
3257	iow.set <myclass, &myclass::io_cb> (&obj);	3432	iow.set <myclass, &myclass::io_cb> (&obj);
3258		3433
3259	=item w->set (object *)	3434	=item w->set (object *)
3260
3261	This is an B<experimental> feature that might go away in a future version.
3262		3435
3263	This is a variation of a method callback - leaving out the method to call	3436	This is a variation of a method callback - leaving out the method to call
3264	will default the method to C<operator ()>, which makes it possible to use	3437	will default the method to C<operator ()>, which makes it possible to use
3265	functor objects without having to manually specify the C<operator ()> all	3438	functor objects without having to manually specify the C<operator ()> all
3266	the time. Incidentally, you can then also leave out the template argument	3439	the time. Incidentally, you can then also leave out the template argument
…		…
3299	Example: Use a plain function as callback.	3472	Example: Use a plain function as callback.
3300		3473
3301	static void io_cb (ev::io &w, int revents) { }	3474	static void io_cb (ev::io &w, int revents) { }
3302	iow.set <io_cb> ();	3475	iow.set <io_cb> ();
3303		3476
3304	=item w->set (struct ev_loop *)	3477	=item w->set (loop)
3305		3478
3306	Associates a different C<struct ev_loop> with this watcher. You can only	3479	Associates a different C<struct ev_loop> with this watcher. You can only
3307	do this when the watcher is inactive (and not pending either).	3480	do this when the watcher is inactive (and not pending either).
3308		3481
3309	=item w->set ([arguments])	3482	=item w->set ([arguments])
3310		3483
3311	Basically the same as C<ev_TYPE_set>, with the same arguments. Must be	3484	Basically the same as C<ev_TYPE_set>, with the same arguments. Either this
3312	called at least once. Unlike the C counterpart, an active watcher gets	3485	method or a suitable start method must be called at least once. Unlike the
3313	automatically stopped and restarted when reconfiguring it with this	3486	C counterpart, an active watcher gets automatically stopped and restarted
3314	method.	3487	when reconfiguring it with this method.
3315		3488
3316	=item w->start ()	3489	=item w->start ()
3317		3490
3318	Starts the watcher. Note that there is no C<loop> argument, as the	3491	Starts the watcher. Note that there is no C<loop> argument, as the
3319	constructor already stores the event loop.	3492	constructor already stores the event loop.
3320		3493
		3494	=item w->start ([arguments])
		3495
		3496	Instead of calling C<set> and C<start> methods separately, it is often
		3497	convenient to wrap them in one call. Uses the same type of arguments as
		3498	the configure C<set> method of the watcher.
		3499
3321	=item w->stop ()	3500	=item w->stop ()
3322		3501
3323	Stops the watcher if it is active. Again, no C<loop> argument.	3502	Stops the watcher if it is active. Again, no C<loop> argument.
3324		3503
3325	=item w->again () (C<ev::timer>, C<ev::periodic> only)	3504	=item w->again () (C<ev::timer>, C<ev::periodic> only)
…		…
3337		3516
3338	=back	3517	=back
3339		3518
3340	=back	3519	=back
3341		3520
3342	Example: Define a class with an IO and idle watcher, start one of them in	3521	Example: Define a class with two I/O and idle watchers, start the I/O
3343	the constructor.	3522	watchers in the constructor.
3344		3523
3345	class myclass	3524	class myclass
3346	{	3525	{
3347	ev::io io ; void io_cb (ev::io &w, int revents);	3526	ev::io io ; void io_cb (ev::io &w, int revents);
		3527	ev::io2 io2 ; void io2_cb (ev::io &w, int revents);
3348	ev::idle idle; void idle_cb (ev::idle &w, int revents);	3528	ev::idle idle; void idle_cb (ev::idle &w, int revents);
3349		3529
3350	myclass (int fd)	3530	myclass (int fd)
3351	{	3531	{
3352	io .set <myclass, &myclass::io_cb > (this);	3532	io .set <myclass, &myclass::io_cb > (this);
		3533	io2 .set <myclass, &myclass::io2_cb > (this);
3353	idle.set <myclass, &myclass::idle_cb> (this);	3534	idle.set <myclass, &myclass::idle_cb> (this);
3354		3535
3355	io.start (fd, ev::READ);	3536	io.set (fd, ev::WRITE); // configure the watcher
		3537	io.start (); // start it whenever convenient
		3538
		3539	io2.start (fd, ev::READ); // set + start in one call
3356	}	3540	}
3357	};	3541	};
3358		3542
3359		3543
3360	=head1 OTHER LANGUAGE BINDINGS	3544	=head1 OTHER LANGUAGE BINDINGS
…		…
3406	=item Ocaml	3590	=item Ocaml
3407		3591
3408	Erkki Seppala has written Ocaml bindings for libev, to be found at	3592	Erkki Seppala has written Ocaml bindings for libev, to be found at
3409	L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>.	3593	L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>.
3410		3594
		3595	=item Lua
		3596
		3597	Brian Maher has written a partial interface to libev for lua (at the
		3598	time of this writing, only C<ev_io> and C<ev_timer>), to be found at
		3599	L<http://github.com/brimworks/lua-ev>.
		3600
3411	=back	3601	=back
3412		3602
3413		3603
3414	=head1 MACRO MAGIC	3604	=head1 MACRO MAGIC
3415		3605
…		…
3428	loop argument"). The C<EV_A> form is used when this is the sole argument,	3618	loop argument"). The C<EV_A> form is used when this is the sole argument,
3429	C<EV_A_> is used when other arguments are following. Example:	3619	C<EV_A_> is used when other arguments are following. Example:
3430		3620
3431	ev_unref (EV_A);	3621	ev_unref (EV_A);
3432	ev_timer_add (EV_A_ watcher);	3622	ev_timer_add (EV_A_ watcher);
3433	ev_loop (EV_A_ 0);	3623	ev_run (EV_A_ 0);
3434		3624
3435	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	3625	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
3436	which is often provided by the following macro.	3626	which is often provided by the following macro.
3437		3627
3438	=item C<EV_P>, C<EV_P_>	3628	=item C<EV_P>, C<EV_P_>
…		…
3478	}	3668	}
3479		3669
3480	ev_check check;	3670	ev_check check;
3481	ev_check_init (&check, check_cb);	3671	ev_check_init (&check, check_cb);
3482	ev_check_start (EV_DEFAULT_ &check);	3672	ev_check_start (EV_DEFAULT_ &check);
3483	ev_loop (EV_DEFAULT_ 0);	3673	ev_run (EV_DEFAULT_ 0);
3484		3674
3485	=head1 EMBEDDING	3675	=head1 EMBEDDING
3486		3676
3487	Libev can (and often is) directly embedded into host	3677	Libev can (and often is) directly embedded into host
3488	applications. Examples of applications that embed it include the Deliantra	3678	applications. Examples of applications that embed it include the Deliantra
…		…
3568	libev.m4	3758	libev.m4
3569		3759
3570	=head2 PREPROCESSOR SYMBOLS/MACROS	3760	=head2 PREPROCESSOR SYMBOLS/MACROS
3571		3761
3572	Libev can be configured via a variety of preprocessor symbols you have to	3762	Libev can be configured via a variety of preprocessor symbols you have to
3573	define before including any of its files. The default in the absence of	3763	define before including (or compiling) any of its files. The default in
3574	autoconf is documented for every option.	3764	the absence of autoconf is documented for every option.
		3765
		3766	Symbols marked with "(h)" do not change the ABI, and can have different
		3767	values when compiling libev vs. including F<ev.h>, so it is permissible
		3768	to redefine them before including F<ev.h> without breaking compatibility
		3769	to a compiled library. All other symbols change the ABI, which means all
		3770	users of libev and the libev code itself must be compiled with compatible
		3771	settings.
3575		3772
3576	=over 4	3773	=over 4
3577		3774
		3775	=item EV_COMPAT3 (h)
		3776
		3777	Backwards compatibility is a major concern for libev. This is why this
		3778	release of libev comes with wrappers for the functions and symbols that
		3779	have been renamed between libev version 3 and 4.
		3780
		3781	You can disable these wrappers (to test compatibility with future
		3782	versions) by defining C<EV_COMPAT3> to C<0> when compiling your
		3783	sources. This has the additional advantage that you can drop the C<struct>
		3784	from C<struct ev_loop> declarations, as libev will provide an C<ev_loop>
		3785	typedef in that case.
		3786
		3787	In some future version, the default for C<EV_COMPAT3> will become C<0>,
		3788	and in some even more future version the compatibility code will be
		3789	removed completely.
		3790
3578	=item EV_STANDALONE	3791	=item EV_STANDALONE (h)
3579		3792
3580	Must always be C<1> if you do not use autoconf configuration, which	3793	Must always be C<1> if you do not use autoconf configuration, which
3581	keeps libev from including F<config.h>, and it also defines dummy	3794	keeps libev from including F<config.h>, and it also defines dummy
3582	implementations for some libevent functions (such as logging, which is not	3795	implementations for some libevent functions (such as logging, which is not
3583	supported). It will also not define any of the structs usually found in	3796	supported). It will also not define any of the structs usually found in
3584	F<event.h> that are not directly supported by the libev core alone.	3797	F<event.h> that are not directly supported by the libev core alone.
3585		3798
3586	In stanbdalone mode, libev will still try to automatically deduce the	3799	In standalone mode, libev will still try to automatically deduce the
3587	configuration, but has to be more conservative.	3800	configuration, but has to be more conservative.
3588		3801
3589	=item EV_USE_MONOTONIC	3802	=item EV_USE_MONOTONIC
3590		3803
3591	If defined to be C<1>, libev will try to detect the availability of the	3804	If defined to be C<1>, libev will try to detect the availability of the
…		…
3656	be used is the winsock select). This means that it will call	3869	be used is the winsock select). This means that it will call
3657	C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise,	3870	C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise,
3658	it is assumed that all these functions actually work on fds, even	3871	it is assumed that all these functions actually work on fds, even
3659	on win32. Should not be defined on non-win32 platforms.	3872	on win32. Should not be defined on non-win32 platforms.
3660		3873
3661	=item EV_FD_TO_WIN32_HANDLE	3874	=item EV_FD_TO_WIN32_HANDLE(fd)
3662		3875
3663	If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map	3876	If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map
3664	file descriptors to socket handles. When not defining this symbol (the	3877	file descriptors to socket handles. When not defining this symbol (the
3665	default), then libev will call C<_get_osfhandle>, which is usually	3878	default), then libev will call C<_get_osfhandle>, which is usually
3666	correct. In some cases, programs use their own file descriptor management,	3879	correct. In some cases, programs use their own file descriptor management,
3667	in which case they can provide this function to map fds to socket handles.	3880	in which case they can provide this function to map fds to socket handles.
		3881
		3882	=item EV_WIN32_HANDLE_TO_FD(handle)
		3883
		3884	If C<EV_SELECT_IS_WINSOCKET> then libev maps handles to file descriptors
		3885	using the standard C<_open_osfhandle> function. For programs implementing
		3886	their own fd to handle mapping, overwriting this function makes it easier
		3887	to do so. This can be done by defining this macro to an appropriate value.
		3888
		3889	=item EV_WIN32_CLOSE_FD(fd)
		3890
		3891	If programs implement their own fd to handle mapping on win32, then this
		3892	macro can be used to override the C<close> function, useful to unregister
		3893	file descriptors again. Note that the replacement function has to close
		3894	the underlying OS handle.
3668		3895
3669	=item EV_USE_POLL	3896	=item EV_USE_POLL
3670		3897
3671	If defined to be C<1>, libev will compile in support for the C<poll>(2)	3898	If defined to be C<1>, libev will compile in support for the C<poll>(2)
3672	backend. Otherwise it will be enabled on non-win32 platforms. It	3899	backend. Otherwise it will be enabled on non-win32 platforms. It
…		…
3719	as well as for signal and thread safety in C<ev_async> watchers.	3946	as well as for signal and thread safety in C<ev_async> watchers.
3720		3947
3721	In the absence of this define, libev will use C<sig_atomic_t volatile>	3948	In the absence of this define, libev will use C<sig_atomic_t volatile>
3722	(from F<signal.h>), which is usually good enough on most platforms.	3949	(from F<signal.h>), which is usually good enough on most platforms.
3723		3950
3724	=item EV_H	3951	=item EV_H (h)
3725		3952
3726	The name of the F<ev.h> header file used to include it. The default if	3953	The name of the F<ev.h> header file used to include it. The default if
3727	undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be	3954	undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be
3728	used to virtually rename the F<ev.h> header file in case of conflicts.	3955	used to virtually rename the F<ev.h> header file in case of conflicts.
3729		3956
3730	=item EV_CONFIG_H	3957	=item EV_CONFIG_H (h)
3731		3958
3732	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override	3959	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override
3733	F<ev.c>'s idea of where to find the F<config.h> file, similarly to	3960	F<ev.c>'s idea of where to find the F<config.h> file, similarly to
3734	C<EV_H>, above.	3961	C<EV_H>, above.
3735		3962
3736	=item EV_EVENT_H	3963	=item EV_EVENT_H (h)
3737		3964
3738	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea	3965	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea
3739	of how the F<event.h> header can be found, the default is C<"event.h">.	3966	of how the F<event.h> header can be found, the default is C<"event.h">.
3740		3967
3741	=item EV_PROTOTYPES	3968	=item EV_PROTOTYPES (h)
3742		3969
3743	If defined to be C<0>, then F<ev.h> will not define any function	3970	If defined to be C<0>, then F<ev.h> will not define any function
3744	prototypes, but still define all the structs and other symbols. This is	3971	prototypes, but still define all the structs and other symbols. This is
3745	occasionally useful if you want to provide your own wrapper functions	3972	occasionally useful if you want to provide your own wrapper functions
3746	around libev functions.	3973	around libev functions.
…		…
3768	fine.	3995	fine.
3769		3996
3770	If your embedding application does not need any priorities, defining these	3997	If your embedding application does not need any priorities, defining these
3771	both to C<0> will save some memory and CPU.	3998	both to C<0> will save some memory and CPU.
3772		3999
3773	=item EV_PERIODIC_ENABLE	4000	=item EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE,
		4001	EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE,
		4002	EV_ASYNC_ENABLE, EV_CHILD_ENABLE.
3774		4003
3775	If undefined or defined to be C<1>, then periodic timers are supported. If	4004	If undefined or defined to be C<1> (and the platform supports it), then
3776	defined to be C<0>, then they are not. Disabling them saves a few kB of	4005	the respective watcher type is supported. If defined to be C<0>, then it
3777	code.	4006	is not. Disabling watcher types mainly saves code size.
3778		4007
3779	=item EV_IDLE_ENABLE	4008	=item EV_FEATURES
3780
3781	If undefined or defined to be C<1>, then idle watchers are supported. If
3782	defined to be C<0>, then they are not. Disabling them saves a few kB of
3783	code.
3784
3785	=item EV_EMBED_ENABLE
3786
3787	If undefined or defined to be C<1>, then embed watchers are supported. If
3788	defined to be C<0>, then they are not. Embed watchers rely on most other
3789	watcher types, which therefore must not be disabled.
3790
3791	=item EV_STAT_ENABLE
3792
3793	If undefined or defined to be C<1>, then stat watchers are supported. If
3794	defined to be C<0>, then they are not.
3795
3796	=item EV_FORK_ENABLE
3797
3798	If undefined or defined to be C<1>, then fork watchers are supported. If
3799	defined to be C<0>, then they are not.
3800
3801	=item EV_ASYNC_ENABLE
3802
3803	If undefined or defined to be C<1>, then async watchers are supported. If
3804	defined to be C<0>, then they are not.
3805
3806	=item EV_MINIMAL
3807		4009
3808	If you need to shave off some kilobytes of code at the expense of some	4010	If you need to shave off some kilobytes of code at the expense of some
3809	speed (but with the full API), define this symbol to C<1>. Currently this	4011	speed (but with the full API), you can define this symbol to request
3810	is used to override some inlining decisions, saves roughly 30% code size	4012	certain subsets of functionality. The default is to enable all features
3811	on amd64. It also selects a much smaller 2-heap for timer management over	4013	that can be enabled on the platform.
3812	the default 4-heap.
3813		4014
3814	You can save even more by disabling watcher types you do not need	4015	A typical way to use this symbol is to define it to C<0> (or to a bitset
3815	and setting C<EV_MAXPRI> == C<EV_MINPRI>. Also, disabling C<assert>	4016	with some broad features you want) and then selectively re-enable
3816	(C<-DNDEBUG>) will usually reduce code size a lot.	4017	additional parts you want, for example if you want everything minimal,
		4018	but multiple event loop support, async and child watchers and the poll
		4019	backend, use this:
3817		4020
3818	Defining C<EV_MINIMAL> to C<2> will additionally reduce the core API to	4021	#define EV_FEATURES 0
3819	provide a bare-bones event library. See C<ev.h> for details on what parts	4022	#define EV_MULTIPLICITY 1
3820	of the API are still available, and do not complain if this subset changes	4023	#define EV_USE_POLL 1
3821	over time.	4024	#define EV_CHILD_ENABLE 1
		4025	#define EV_ASYNC_ENABLE 1
		4026
		4027	The actual value is a bitset, it can be a combination of the following
		4028	values:
		4029
		4030	=over 4
		4031
		4032	=item C<1> - faster/larger code
		4033
		4034	Use larger code to speed up some operations.
		4035
		4036	Currently this is used to override some inlining decisions (enlarging the
		4037	code size by roughly 30% on amd64).
		4038
		4039	When optimising for size, use of compiler flags such as C<-Os> with
		4040	gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of
		4041	assertions.
		4042
		4043	=item C<2> - faster/larger data structures
		4044
		4045	Replaces the small 2-heap for timer management by a faster 4-heap, larger
		4046	hash table sizes and so on. This will usually further increase code size
		4047	and can additionally have an effect on the size of data structures at
		4048	runtime.
		4049
		4050	=item C<4> - full API configuration
		4051
		4052	This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and
		4053	enables multiplicity (C<EV_MULTIPLICITY>=1).
		4054
		4055	=item C<8> - full API
		4056
		4057	This enables a lot of the "lesser used" API functions. See C<ev.h> for
		4058	details on which parts of the API are still available without this
		4059	feature, and do not complain if this subset changes over time.
		4060
		4061	=item C<16> - enable all optional watcher types
		4062
		4063	Enables all optional watcher types. If you want to selectively enable
		4064	only some watcher types other than I/O and timers (e.g. prepare,
		4065	embed, async, child...) you can enable them manually by defining
		4066	C<EV_watchertype_ENABLE> to C<1> instead.
		4067
		4068	=item C<32> - enable all backends
		4069
		4070	This enables all backends - without this feature, you need to enable at
		4071	least one backend manually (C<EV_USE_SELECT> is a good choice).
		4072
		4073	=item C<64> - enable OS-specific "helper" APIs
		4074
		4075	Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by
		4076	default.
		4077
		4078	=back
		4079
		4080	Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0>
		4081	reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb
		4082	code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O
		4083	watchers, timers and monotonic clock support.
		4084
		4085	With an intelligent-enough linker (gcc+binutils are intelligent enough
		4086	when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by
		4087	your program might be left out as well - a binary starting a timer and an
		4088	I/O watcher then might come out at only 5Kb.
		4089
		4090	=item EV_AVOID_STDIO
		4091
		4092	If this is set to C<1> at compiletime, then libev will avoid using stdio
		4093	functions (printf, scanf, perror etc.). This will increase the code size
		4094	somewhat, but if your program doesn't otherwise depend on stdio and your
		4095	libc allows it, this avoids linking in the stdio library which is quite
		4096	big.
		4097
		4098	Note that error messages might become less precise when this option is
		4099	enabled.
3822		4100
3823	=item EV_NSIG	4101	=item EV_NSIG
3824		4102
3825	The highest supported signal number, +1 (or, the number of	4103	The highest supported signal number, +1 (or, the number of
3826	signals): Normally, libev tries to deduce the maximum number of signals	4104	signals): Normally, libev tries to deduce the maximum number of signals
3827	automatically, but sometimes this fails, in which case it can be	4105	automatically, but sometimes this fails, in which case it can be
3828	specified. Also, using a lower number than detected (C<32> should be	4106	specified. Also, using a lower number than detected (C<32> should be
3829	good for about any system in existance) can save some memory, as libev	4107	good for about any system in existence) can save some memory, as libev
3830	statically allocates some 12-24 bytes per signal number.	4108	statically allocates some 12-24 bytes per signal number.
3831		4109
3832	=item EV_PID_HASHSIZE	4110	=item EV_PID_HASHSIZE
3833		4111
3834	C<ev_child> watchers use a small hash table to distribute workload by	4112	C<ev_child> watchers use a small hash table to distribute workload by
3835	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more	4113	pid. The default size is C<16> (or C<1> with C<EV_FEATURES> disabled),
3836	than enough. If you need to manage thousands of children you might want to	4114	usually more than enough. If you need to manage thousands of children you
3837	increase this value (I<must> be a power of two).	4115	might want to increase this value (I<must> be a power of two).
3838		4116
3839	=item EV_INOTIFY_HASHSIZE	4117	=item EV_INOTIFY_HASHSIZE
3840		4118
3841	C<ev_stat> watchers use a small hash table to distribute workload by	4119	C<ev_stat> watchers use a small hash table to distribute workload by
3842	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),	4120	inotify watch id. The default size is C<16> (or C<1> with C<EV_FEATURES>
3843	usually more than enough. If you need to manage thousands of C<ev_stat>	4121	disabled), usually more than enough. If you need to manage thousands of
3844	watchers you might want to increase this value (I<must> be a power of	4122	C<ev_stat> watchers you might want to increase this value (I<must> be a
3845	two).	4123	power of two).
3846		4124
3847	=item EV_USE_4HEAP	4125	=item EV_USE_4HEAP
3848		4126
3849	Heaps are not very cache-efficient. To improve the cache-efficiency of the	4127	Heaps are not very cache-efficient. To improve the cache-efficiency of the
3850	timer and periodics heaps, libev uses a 4-heap when this symbol is defined	4128	timer and periodics heaps, libev uses a 4-heap when this symbol is defined
3851	to C<1>. The 4-heap uses more complicated (longer) code but has noticeably	4129	to C<1>. The 4-heap uses more complicated (longer) code but has noticeably
3852	faster performance with many (thousands) of watchers.	4130	faster performance with many (thousands) of watchers.
3853		4131
3854	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>	4132	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3855	(disabled).	4133	will be C<0>.
3856		4134
3857	=item EV_HEAP_CACHE_AT	4135	=item EV_HEAP_CACHE_AT
3858		4136
3859	Heaps are not very cache-efficient. To improve the cache-efficiency of the	4137	Heaps are not very cache-efficient. To improve the cache-efficiency of the
3860	timer and periodics heaps, libev can cache the timestamp (I<at>) within	4138	timer and periodics heaps, libev can cache the timestamp (I<at>) within
3861	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),	4139	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),
3862	which uses 8-12 bytes more per watcher and a few hundred bytes more code,	4140	which uses 8-12 bytes more per watcher and a few hundred bytes more code,
3863	but avoids random read accesses on heap changes. This improves performance	4141	but avoids random read accesses on heap changes. This improves performance
3864	noticeably with many (hundreds) of watchers.	4142	noticeably with many (hundreds) of watchers.
3865		4143
3866	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>	4144	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3867	(disabled).	4145	will be C<0>.
3868		4146
3869	=item EV_VERIFY	4147	=item EV_VERIFY
3870		4148
3871	Controls how much internal verification (see C<ev_loop_verify ()>) will	4149	Controls how much internal verification (see C<ev_verify ()>) will
3872	be done: If set to C<0>, no internal verification code will be compiled	4150	be done: If set to C<0>, no internal verification code will be compiled
3873	in. If set to C<1>, then verification code will be compiled in, but not	4151	in. If set to C<1>, then verification code will be compiled in, but not
3874	called. If set to C<2>, then the internal verification code will be	4152	called. If set to C<2>, then the internal verification code will be
3875	called once per loop, which can slow down libev. If set to C<3>, then the	4153	called once per loop, which can slow down libev. If set to C<3>, then the
3876	verification code will be called very frequently, which will slow down	4154	verification code will be called very frequently, which will slow down
3877	libev considerably.	4155	libev considerably.
3878		4156
3879	The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be	4157	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3880	C<0>.	4158	will be C<0>.
3881		4159
3882	=item EV_COMMON	4160	=item EV_COMMON
3883		4161
3884	By default, all watchers have a C<void *data> member. By redefining	4162	By default, all watchers have a C<void *data> member. By redefining
3885	this macro to a something else you can include more and other types of	4163	this macro to something else you can include more and other types of
3886	members. You have to define it each time you include one of the files,	4164	members. You have to define it each time you include one of the files,
3887	though, and it must be identical each time.	4165	though, and it must be identical each time.
3888		4166
3889	For example, the perl EV module uses something like this:	4167	For example, the perl EV module uses something like this:
3890		4168
…		…
3943	file.	4221	file.
3944		4222
3945	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	4223	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
3946	that everybody includes and which overrides some configure choices:	4224	that everybody includes and which overrides some configure choices:
3947		4225
3948	#define EV_MINIMAL 1	4226	#define EV_FEATURES 8
3949	#define EV_USE_POLL 0	4227	#define EV_USE_SELECT 1
3950	#define EV_MULTIPLICITY 0
3951	#define EV_PERIODIC_ENABLE 0	4228	#define EV_PREPARE_ENABLE 1
		4229	#define EV_IDLE_ENABLE 1
3952	#define EV_STAT_ENABLE 0	4230	#define EV_SIGNAL_ENABLE 1
3953	#define EV_FORK_ENABLE 0	4231	#define EV_CHILD_ENABLE 1
		4232	#define EV_USE_STDEXCEPT 0
3954	#define EV_CONFIG_H <config.h>	4233	#define EV_CONFIG_H <config.h>
3955	#define EV_MINPRI 0
3956	#define EV_MAXPRI 0
3957		4234
3958	#include "ev++.h"	4235	#include "ev++.h"
3959		4236
3960	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	4237	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
3961		4238
…		…
4092	userdata *u = ev_userdata (EV_A);	4369	userdata *u = ev_userdata (EV_A);
4093	pthread_mutex_lock (&u->lock);	4370	pthread_mutex_lock (&u->lock);
4094	}	4371	}
4095		4372
4096	The event loop thread first acquires the mutex, and then jumps straight	4373	The event loop thread first acquires the mutex, and then jumps straight
4097	into C<ev_loop>:	4374	into C<ev_run>:
4098		4375
4099	void *	4376	void *
4100	l_run (void *thr_arg)	4377	l_run (void *thr_arg)
4101	{	4378	{
4102	struct ev_loop *loop = (struct ev_loop *)thr_arg;	4379	struct ev_loop *loop = (struct ev_loop *)thr_arg;
4103		4380
4104	l_acquire (EV_A);	4381	l_acquire (EV_A);
4105	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);	4382	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
4106	ev_loop (EV_A_ 0);	4383	ev_run (EV_A_ 0);
4107	l_release (EV_A);	4384	l_release (EV_A);
4108		4385
4109	return 0;	4386	return 0;
4110	}	4387	}
4111		4388
…		…
4163		4440
4164	=head3 COROUTINES	4441	=head3 COROUTINES
4165		4442
4166	Libev is very accommodating to coroutines ("cooperative threads"):	4443	Libev is very accommodating to coroutines ("cooperative threads"):
4167	libev fully supports nesting calls to its functions from different	4444	libev fully supports nesting calls to its functions from different
4168	coroutines (e.g. you can call C<ev_loop> on the same loop from two	4445	coroutines (e.g. you can call C<ev_run> on the same loop from two
4169	different coroutines, and switch freely between both coroutines running	4446	different coroutines, and switch freely between both coroutines running
4170	the loop, as long as you don't confuse yourself). The only exception is	4447	the loop, as long as you don't confuse yourself). The only exception is
4171	that you must not do this from C<ev_periodic> reschedule callbacks.	4448	that you must not do this from C<ev_periodic> reschedule callbacks.
4172		4449
4173	Care has been taken to ensure that libev does not keep local state inside	4450	Care has been taken to ensure that libev does not keep local state inside
4174	C<ev_loop>, and other calls do not usually allow for coroutine switches as	4451	C<ev_run>, and other calls do not usually allow for coroutine switches as
4175	they do not call any callbacks.	4452	they do not call any callbacks.
4176		4453
4177	=head2 COMPILER WARNINGS	4454	=head2 COMPILER WARNINGS
4178		4455
4179	Depending on your compiler and compiler settings, you might get no or a	4456	Depending on your compiler and compiler settings, you might get no or a
…		…
4190	maintainable.	4467	maintainable.
4191		4468
4192	And of course, some compiler warnings are just plain stupid, or simply	4469	And of course, some compiler warnings are just plain stupid, or simply
4193	wrong (because they don't actually warn about the condition their message	4470	wrong (because they don't actually warn about the condition their message
4194	seems to warn about). For example, certain older gcc versions had some	4471	seems to warn about). For example, certain older gcc versions had some
4195	warnings that resulted an extreme number of false positives. These have	4472	warnings that resulted in an extreme number of false positives. These have
4196	been fixed, but some people still insist on making code warn-free with	4473	been fixed, but some people still insist on making code warn-free with
4197	such buggy versions.	4474	such buggy versions.
4198		4475
4199	While libev is written to generate as few warnings as possible,	4476	While libev is written to generate as few warnings as possible,
4200	"warn-free" code is not a goal, and it is recommended not to build libev	4477	"warn-free" code is not a goal, and it is recommended not to build libev
…		…
4236	I suggest using suppression lists.	4513	I suggest using suppression lists.
4237		4514
4238		4515
4239	=head1 PORTABILITY NOTES	4516	=head1 PORTABILITY NOTES
4240		4517
		4518	=head2 GNU/LINUX 32 BIT LIMITATIONS
		4519
		4520	GNU/Linux is the only common platform that supports 64 bit file/large file
		4521	interfaces but I<disables> them by default.
		4522
		4523	That means that libev compiled in the default environment doesn't support
		4524	files larger than 2GiB or so, which mainly affects C<ev_stat> watchers.
		4525
		4526	Unfortunately, many programs try to work around this GNU/Linux issue
		4527	by enabling the large file API, which makes them incompatible with the
		4528	standard libev compiled for their system.
		4529
		4530	Likewise, libev cannot enable the large file API itself as this would
		4531	suddenly make it incompatible to the default compile time environment,
		4532	i.e. all programs not using special compile switches.
		4533
		4534	=head2 OS/X AND DARWIN BUGS
		4535
		4536	The whole thing is a bug if you ask me - basically any system interface
		4537	you touch is broken, whether it is locales, poll, kqueue or even the
		4538	OpenGL drivers.
		4539
		4540	=head3 C<kqueue> is buggy
		4541
		4542	The kqueue syscall is broken in all known versions - most versions support
		4543	only sockets, many support pipes.
		4544
		4545	Libev tries to work around this by not using C<kqueue> by default on this
		4546	rotten platform, but of course you can still ask for it when creating a
		4547	loop - embedding a socket-only kqueue loop into a select-based one is
		4548	probably going to work well.
		4549
		4550	=head3 C<poll> is buggy
		4551
		4552	Instead of fixing C<kqueue>, Apple replaced their (working) C<poll>
		4553	implementation by something calling C<kqueue> internally around the 10.5.6
		4554	release, so now C<kqueue> I<and> C<poll> are broken.
		4555
		4556	Libev tries to work around this by not using C<poll> by default on
		4557	this rotten platform, but of course you can still ask for it when creating
		4558	a loop.
		4559
		4560	=head3 C<select> is buggy
		4561
		4562	All that's left is C<select>, and of course Apple found a way to fuck this
		4563	one up as well: On OS/X, C<select> actively limits the number of file
		4564	descriptors you can pass in to 1024 - your program suddenly crashes when
		4565	you use more.
		4566
		4567	There is an undocumented "workaround" for this - defining
		4568	C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should>
		4569	work on OS/X.
		4570
		4571	=head2 SOLARIS PROBLEMS AND WORKAROUNDS
		4572
		4573	=head3 C<errno> reentrancy
		4574
		4575	The default compile environment on Solaris is unfortunately so
		4576	thread-unsafe that you can't even use components/libraries compiled
		4577	without C<-D_REENTRANT> in a threaded program, which, of course, isn't
		4578	defined by default. A valid, if stupid, implementation choice.
		4579
		4580	If you want to use libev in threaded environments you have to make sure
		4581	it's compiled with C<_REENTRANT> defined.
		4582
		4583	=head3 Event port backend
		4584
		4585	The scalable event interface for Solaris is called "event
		4586	ports". Unfortunately, this mechanism is very buggy in all major
		4587	releases. If you run into high CPU usage, your program freezes or you get
		4588	a large number of spurious wakeups, make sure you have all the relevant
		4589	and latest kernel patches applied. No, I don't know which ones, but there
		4590	are multiple ones to apply, and afterwards, event ports actually work
		4591	great.
		4592
		4593	If you can't get it to work, you can try running the program by setting
		4594	the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and
		4595	C<select> backends.
		4596
		4597	=head2 AIX POLL BUG
		4598
		4599	AIX unfortunately has a broken C<poll.h> header. Libev works around
		4600	this by trying to avoid the poll backend altogether (i.e. it's not even
		4601	compiled in), which normally isn't a big problem as C<select> works fine
		4602	with large bitsets on AIX, and AIX is dead anyway.
		4603
4241	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS	4604	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
		4605
		4606	=head3 General issues
4242		4607
4243	Win32 doesn't support any of the standards (e.g. POSIX) that libev	4608	Win32 doesn't support any of the standards (e.g. POSIX) that libev
4244	requires, and its I/O model is fundamentally incompatible with the POSIX	4609	requires, and its I/O model is fundamentally incompatible with the POSIX
4245	model. Libev still offers limited functionality on this platform in	4610	model. Libev still offers limited functionality on this platform in
4246	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	4611	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
4247	descriptors. This only applies when using Win32 natively, not when using	4612	descriptors. This only applies when using Win32 natively, not when using
4248	e.g. cygwin.	4613	e.g. cygwin. Actually, it only applies to the microsofts own compilers,
		4614	as every compielr comes with a slightly differently broken/incompatible
		4615	environment.
4249		4616
4250	Lifting these limitations would basically require the full	4617	Lifting these limitations would basically require the full
4251	re-implementation of the I/O system. If you are into these kinds of	4618	re-implementation of the I/O system. If you are into this kind of thing,
4252	things, then note that glib does exactly that for you in a very portable	4619	then note that glib does exactly that for you in a very portable way (note
4253	way (note also that glib is the slowest event library known to man).	4620	also that glib is the slowest event library known to man).
4254		4621
4255	There is no supported compilation method available on windows except	4622	There is no supported compilation method available on windows except
4256	embedding it into other applications.	4623	embedding it into other applications.
4257		4624
4258	Sensible signal handling is officially unsupported by Microsoft - libev	4625	Sensible signal handling is officially unsupported by Microsoft - libev
…		…
4286	you do I<not> compile the F<ev.c> or any other embedded source files!):	4653	you do I<not> compile the F<ev.c> or any other embedded source files!):
4287		4654
4288	#include "evwrap.h"	4655	#include "evwrap.h"
4289	#include "ev.c"	4656	#include "ev.c"
4290		4657
4291	=over 4
4292
4293	=item The winsocket select function	4658	=head3 The winsocket C<select> function
4294		4659
4295	The winsocket C<select> function doesn't follow POSIX in that it	4660	The winsocket C<select> function doesn't follow POSIX in that it
4296	requires socket I<handles> and not socket I<file descriptors> (it is	4661	requires socket I<handles> and not socket I<file descriptors> (it is
4297	also extremely buggy). This makes select very inefficient, and also	4662	also extremely buggy). This makes select very inefficient, and also
4298	requires a mapping from file descriptors to socket handles (the Microsoft	4663	requires a mapping from file descriptors to socket handles (the Microsoft
…		…
4307	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */	4672	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
4308		4673
4309	Note that winsockets handling of fd sets is O(n), so you can easily get a	4674	Note that winsockets handling of fd sets is O(n), so you can easily get a
4310	complexity in the O(n²) range when using win32.	4675	complexity in the O(n²) range when using win32.
4311		4676
4312	=item Limited number of file descriptors	4677	=head3 Limited number of file descriptors
4313		4678
4314	Windows has numerous arbitrary (and low) limits on things.	4679	Windows has numerous arbitrary (and low) limits on things.
4315		4680
4316	Early versions of winsocket's select only supported waiting for a maximum	4681	Early versions of winsocket's select only supported waiting for a maximum
4317	of C<64> handles (probably owning to the fact that all windows kernels	4682	of C<64> handles (probably owning to the fact that all windows kernels
…		…
4332	runtime libraries. This might get you to about C<512> or C<2048> sockets	4697	runtime libraries. This might get you to about C<512> or C<2048> sockets
4333	(depending on windows version and/or the phase of the moon). To get more,	4698	(depending on windows version and/or the phase of the moon). To get more,
4334	you need to wrap all I/O functions and provide your own fd management, but	4699	you need to wrap all I/O functions and provide your own fd management, but
4335	the cost of calling select (O(n²)) will likely make this unworkable.	4700	the cost of calling select (O(n²)) will likely make this unworkable.
4336		4701
4337	=back
4338
4339	=head2 PORTABILITY REQUIREMENTS	4702	=head2 PORTABILITY REQUIREMENTS
4340		4703
4341	In addition to a working ISO-C implementation and of course the	4704	In addition to a working ISO-C implementation and of course the
4342	backend-specific APIs, libev relies on a few additional extensions:	4705	backend-specific APIs, libev relies on a few additional extensions:
4343		4706
…		…
4381	watchers.	4744	watchers.
4382		4745
4383	=item C<double> must hold a time value in seconds with enough accuracy	4746	=item C<double> must hold a time value in seconds with enough accuracy
4384		4747
4385	The type C<double> is used to represent timestamps. It is required to	4748	The type C<double> is used to represent timestamps. It is required to
4386	have at least 51 bits of mantissa (and 9 bits of exponent), which is good	4749	have at least 51 bits of mantissa (and 9 bits of exponent), which is
4387	enough for at least into the year 4000. This requirement is fulfilled by	4750	good enough for at least into the year 4000 with millisecond accuracy
		4751	(the design goal for libev). This requirement is overfulfilled by
4388	implementations implementing IEEE 754, which is basically all existing	4752	implementations using IEEE 754, which is basically all existing ones. With
4389	ones. With IEEE 754 doubles, you get microsecond accuracy until at least	4753	IEEE 754 doubles, you get microsecond accuracy until at least 2200.
4390	2200.
4391		4754
4392	=back	4755	=back
4393		4756
4394	If you know of other additional requirements drop me a note.	4757	If you know of other additional requirements drop me a note.
4395		4758
…		…
4463	involves iterating over all running async watchers or all signal numbers.	4826	involves iterating over all running async watchers or all signal numbers.
4464		4827
4465	=back	4828	=back
4466		4829
4467		4830
		4831	=head1 PORTING FROM LIBEV 3.X TO 4.X
		4832
		4833	The major version 4 introduced some minor incompatible changes to the API.
		4834
		4835	At the moment, the C<ev.h> header file tries to implement superficial
		4836	compatibility, so most programs should still compile. Those might be
		4837	removed in later versions of libev, so better update early than late.
		4838
		4839	=over 4
		4840
		4841	=item C<ev_default_destroy> and C<ev_default_fork> have been removed
		4842
		4843	These calls can be replaced easily by their C<ev_loop_xxx> counterparts:
		4844
		4845	ev_loop_destroy (EV_DEFAULT);
		4846	ev_loop_fork (EV_DEFAULT);
		4847
		4848	=item function/symbol renames
		4849
		4850	A number of functions and symbols have been renamed:
		4851
		4852	ev_loop => ev_run
		4853	EVLOOP_NONBLOCK => EVRUN_NOWAIT
		4854	EVLOOP_ONESHOT => EVRUN_ONCE
		4855
		4856	ev_unloop => ev_break
		4857	EVUNLOOP_CANCEL => EVBREAK_CANCEL
		4858	EVUNLOOP_ONE => EVBREAK_ONE
		4859	EVUNLOOP_ALL => EVBREAK_ALL
		4860
		4861	EV_TIMEOUT => EV_TIMER
		4862
		4863	ev_loop_count => ev_iteration
		4864	ev_loop_depth => ev_depth
		4865	ev_loop_verify => ev_verify
		4866
		4867	Most functions working on C<struct ev_loop> objects don't have an
		4868	C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and
		4869	associated constants have been renamed to not collide with the C<struct
		4870	ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme
		4871	as all other watcher types. Note that C<ev_loop_fork> is still called
		4872	C<ev_loop_fork> because it would otherwise clash with the C<ev_fork>
		4873	typedef.
		4874
		4875	=item C<EV_COMPAT3> backwards compatibility mechanism
		4876
		4877	The backward compatibility mechanism can be controlled by
		4878	C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING>
		4879	section.
		4880
		4881	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>
		4882
		4883	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different
		4884	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile
		4885	and work, but the library code will of course be larger.
		4886
		4887	=back
		4888
		4889
4468	=head1 GLOSSARY	4890	=head1 GLOSSARY
4469		4891
4470	=over 4	4892	=over 4
4471		4893
4472	=item active	4894	=item active
4473		4895
4474	A watcher is active as long as it has been started (has been attached to	4896	A watcher is active as long as it has been started and not yet stopped.
4475	an event loop) but not yet stopped (disassociated from the event loop).	4897	See L<WATCHER STATES> for details.
4476		4898
4477	=item application	4899	=item application
4478		4900
4479	In this document, an application is whatever is using libev.	4901	In this document, an application is whatever is using libev.
		4902
		4903	=item backend
		4904
		4905	The part of the code dealing with the operating system interfaces.
4480		4906
4481	=item callback	4907	=item callback
4482		4908
4483	The address of a function that is called when some event has been	4909	The address of a function that is called when some event has been
4484	detected. Callbacks are being passed the event loop, the watcher that	4910	detected. Callbacks are being passed the event loop, the watcher that
4485	received the event, and the actual event bitset.	4911	received the event, and the actual event bitset.
4486		4912
4487	=item callback invocation	4913	=item callback/watcher invocation
4488		4914
4489	The act of calling the callback associated with a watcher.	4915	The act of calling the callback associated with a watcher.
4490		4916
4491	=item event	4917	=item event
4492		4918
4493	A change of state of some external event, such as data now being available	4919	A change of state of some external event, such as data now being available
4494	for reading on a file descriptor, time having passed or simply not having	4920	for reading on a file descriptor, time having passed or simply not having
4495	any other events happening anymore.	4921	any other events happening anymore.
4496		4922
4497	In libev, events are represented as single bits (such as C<EV_READ> or	4923	In libev, events are represented as single bits (such as C<EV_READ> or
4498	C<EV_TIMEOUT>).	4924	C<EV_TIMER>).
4499		4925
4500	=item event library	4926	=item event library
4501		4927
4502	A software package implementing an event model and loop.	4928	A software package implementing an event model and loop.
4503		4929
…		…
4511	The model used to describe how an event loop handles and processes	4937	The model used to describe how an event loop handles and processes
4512	watchers and events.	4938	watchers and events.
4513		4939
4514	=item pending	4940	=item pending
4515		4941
4516	A watcher is pending as soon as the corresponding event has been detected,	4942	A watcher is pending as soon as the corresponding event has been
4517	and stops being pending as soon as the watcher will be invoked or its	4943	detected. See L<WATCHER STATES> for details.
4518	pending status is explicitly cleared by the application.
4519
4520	A watcher can be pending, but not active. Stopping a watcher also clears
4521	its pending status.
4522		4944
4523	=item real time	4945	=item real time
4524		4946
4525	The physical time that is observed. It is apparently strictly monotonic :)	4947	The physical time that is observed. It is apparently strictly monotonic :)
4526		4948
…		…
4533	=item watcher	4955	=item watcher
4534		4956
4535	A data structure that describes interest in certain events. Watchers need	4957	A data structure that describes interest in certain events. Watchers need
4536	to be started (attached to an event loop) before they can receive events.	4958	to be started (attached to an event loop) before they can receive events.
4537		4959
4538	=item watcher invocation
4539
4540	The act of calling the callback associated with a watcher.
4541
4542	=back	4960	=back
4543		4961
4544	=head1 AUTHOR	4962	=head1 AUTHOR
4545		4963
4546	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson.	4964	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson.

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