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Revision 1.334 by root, Mon Oct 25 10:30:23 2010 UTC

…		…
26	puts ("stdin ready");	26	puts ("stdin ready");
27	// for one-shot events, one must manually stop the watcher	27	// for one-shot events, one must manually stop the watcher
28	// with its corresponding stop function.	28	// with its corresponding stop function.
29	ev_io_stop (EV_A_ w);	29	ev_io_stop (EV_A_ w);
30		30
31	// this causes all nested ev_loop's to stop iterating	31	// this causes all nested ev_run's to stop iterating
32	ev_unloop (EV_A_ EVUNLOOP_ALL);	32	ev_break (EV_A_ EVBREAK_ALL);
33	}	33	}
34		34
35	// another callback, this time for a time-out	35	// another callback, this time for a time-out
36	static void	36	static void
37	timeout_cb (EV_P_ ev_timer *w, int revents)	37	timeout_cb (EV_P_ ev_timer *w, int revents)
38	{	38	{
39	puts ("timeout");	39	puts ("timeout");
40	// this causes the innermost ev_loop to stop iterating	40	// this causes the innermost ev_run to stop iterating
41	ev_unloop (EV_A_ EVUNLOOP_ONE);	41	ev_break (EV_A_ EVBREAK_ONE);
42	}	42	}
43		43
44	int	44	int
45	main (void)	45	main (void)
46	{	46	{
47	// use the default event loop unless you have special needs	47	// use the default event loop unless you have special needs
48	struct ev_loop *loop = ev_default_loop (0);	48	struct ev_loop *loop = EV_DEFAULT;
49		49
50	// initialise an io watcher, then start it	50	// initialise an io watcher, then start it
51	// this one will watch for stdin to become readable	51	// this one will watch for stdin to become readable
52	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);	52	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);
53	ev_io_start (loop, &stdin_watcher);	53	ev_io_start (loop, &stdin_watcher);
…		…
56	// simple non-repeating 5.5 second timeout	56	// simple non-repeating 5.5 second timeout
57	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);	57	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
58	ev_timer_start (loop, &timeout_watcher);	58	ev_timer_start (loop, &timeout_watcher);
59		59
60	// now wait for events to arrive	60	// now wait for events to arrive
61	ev_loop (loop, 0);	61	ev_run (loop, 0);
62		62
63	// unloop was called, so exit	63	// unloop was called, so exit
64	return 0;	64	return 0;
65	}	65	}
66		66
…		…
75	While this document tries to be as complete as possible in documenting	75	While this document tries to be as complete as possible in documenting
76	libev, its usage and the rationale behind its design, it is not a tutorial	76	libev, its usage and the rationale behind its design, it is not a tutorial
77	on event-based programming, nor will it introduce event-based programming	77	on event-based programming, nor will it introduce event-based programming
78	with libev.	78	with libev.
79		79
80	Familarity with event based programming techniques in general is assumed	80	Familiarity with event based programming techniques in general is assumed
81	throughout this document.	81	throughout this document.
		82
		83	=head1 WHAT TO READ WHEN IN A HURRY
		84
		85	This manual tries to be very detailed, but unfortunately, this also makes
		86	it very long. If you just want to know the basics of libev, I suggest
		87	reading L<ANATOMY OF A WATCHER>, then the L<EXAMPLE PROGRAM> above and
		88	look up the missing functions in L<GLOBAL FUNCTIONS> and the C<ev_io> and
		89	C<ev_timer> sections in L<WATCHER TYPES>.
82		90
83	=head1 ABOUT LIBEV	91	=head1 ABOUT LIBEV
84		92
85	Libev is an event loop: you register interest in certain events (such as a	93	Libev is an event loop: you register interest in certain events (such as a
86	file descriptor being readable or a timeout occurring), and it will manage	94	file descriptor being readable or a timeout occurring), and it will manage
…		…
98	=head2 FEATURES	106	=head2 FEATURES
99		107
100	Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the	108	Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the
101	BSD-specific C<kqueue> and the Solaris-specific event port mechanisms	109	BSD-specific C<kqueue> and the Solaris-specific event port mechanisms
102	for file descriptor events (C<ev_io>), the Linux C<inotify> interface	110	for file descriptor events (C<ev_io>), the Linux C<inotify> interface
103	(for C<ev_stat>), relative timers (C<ev_timer>), absolute timers	111	(for C<ev_stat>), Linux eventfd/signalfd (for faster and cleaner
104	with customised rescheduling (C<ev_periodic>), synchronous signals	112	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	113	timers (C<ev_timer>), absolute timers with customised rescheduling
106	watchers dealing with the event loop mechanism itself (C<ev_idle>,	114	(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	115	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	116	loop mechanism itself (C<ev_idle>, C<ev_embed>, C<ev_prepare> and
109	(C<ev_fork>).	117	C<ev_check> watchers) as well as file watchers (C<ev_stat>) and even
		118	limited support for fork events (C<ev_fork>).
110		119
111	It also is quite fast (see this	120	It also is quite fast (see this
112	L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent	121	L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent
113	for example).	122	for example).
114		123
…		…
117	Libev is very configurable. In this manual the default (and most common)	126	Libev is very configurable. In this manual the default (and most common)
118	configuration will be described, which supports multiple event loops. For	127	configuration will be described, which supports multiple event loops. For
119	more info about various configuration options please have a look at	128	more info about various configuration options please have a look at
120	B<EMBED> section in this manual. If libev was configured without support	129	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	130	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	131	name C<loop> (which is always of type C<struct ev_loop *>) will not have
123	this argument.	132	this argument.
124		133
125	=head2 TIME REPRESENTATION	134	=head2 TIME REPRESENTATION
126		135
127	Libev represents time as a single floating point number, representing	136	Libev represents time as a single floating point number, representing
128	the (fractional) number of seconds since the (POSIX) epoch (somewhere	137	the (fractional) number of seconds since the (POSIX) epoch (in practice
129	near the beginning of 1970, details are complicated, don't ask). This	138	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	139	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	140	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	141	any calculations on it, you should treat it as some floating point value.
		142
133	component C<stamp> might indicate, it is also used for time differences	143	Unlike the name component C<stamp> might indicate, it is also used for
134	throughout libev.	144	time differences (e.g. delays) throughout libev.
135		145
136	=head1 ERROR HANDLING	146	=head1 ERROR HANDLING
137		147
138	Libev knows three classes of errors: operating system errors, usage errors	148	Libev knows three classes of errors: operating system errors, usage errors
139	and internal errors (bugs).	149	and internal errors (bugs).
…		…
163		173
164	=item ev_tstamp ev_time ()	174	=item ev_tstamp ev_time ()
165		175
166	Returns the current time as libev would use it. Please note that the	176	Returns the current time as libev would use it. Please note that the
167	C<ev_now> function is usually faster and also often returns the timestamp	177	C<ev_now> function is usually faster and also often returns the timestamp
168	you actually want to know.	178	you actually want to know. Also interesting is the combination of
		179	C<ev_update_now> and C<ev_now>.
169		180
170	=item ev_sleep (ev_tstamp interval)	181	=item ev_sleep (ev_tstamp interval)
171		182
172	Sleep for the given interval: The current thread will be blocked until	183	Sleep for the given interval: The current thread will be blocked until
173	either it is interrupted or the given time interval has passed. Basically	184	either it is interrupted or the given time interval has passed. Basically
…		…
190	as this indicates an incompatible change. Minor versions are usually	201	as this indicates an incompatible change. Minor versions are usually
191	compatible to older versions, so a larger minor version alone is usually	202	compatible to older versions, so a larger minor version alone is usually
192	not a problem.	203	not a problem.
193		204
194	Example: Make sure we haven't accidentally been linked against the wrong	205	Example: Make sure we haven't accidentally been linked against the wrong
195	version.	206	version (note, however, that this will not detect other ABI mismatches,
		207	such as LFS or reentrancy).
196		208
197	assert (("libev version mismatch",	209	assert (("libev version mismatch",
198	ev_version_major () == EV_VERSION_MAJOR	210	ev_version_major () == EV_VERSION_MAJOR
199	&& ev_version_minor () >= EV_VERSION_MINOR));	211	&& ev_version_minor () >= EV_VERSION_MINOR));
200		212
…		…
211	assert (("sorry, no epoll, no sex",	223	assert (("sorry, no epoll, no sex",
212	ev_supported_backends () & EVBACKEND_EPOLL));	224	ev_supported_backends () & EVBACKEND_EPOLL));
213		225
214	=item unsigned int ev_recommended_backends ()	226	=item unsigned int ev_recommended_backends ()
215		227
216	Return the set of all backends compiled into this binary of libev and also	228	Return the set of all backends compiled into this binary of libev and
217	recommended for this platform. This set is often smaller than the one	229	also recommended for this platform, meaning it will work for most file
		230	descriptor types. This set is often smaller than the one returned by
218	returned by C<ev_supported_backends>, as for example kqueue is broken on	231	C<ev_supported_backends>, as for example kqueue is broken on most BSDs
219	most BSDs and will not be auto-detected unless you explicitly request it	232	and will not be auto-detected unless you explicitly request it (assuming
220	(assuming you know what you are doing). This is the set of backends that	233	you know what you are doing). This is the set of backends that libev will
221	libev will probe for if you specify no backends explicitly.	234	probe for if you specify no backends explicitly.
222		235
223	=item unsigned int ev_embeddable_backends ()	236	=item unsigned int ev_embeddable_backends ()
224		237
225	Returns the set of backends that are embeddable in other event loops. This	238	Returns the set of backends that are embeddable in other event loops. This
226	is the theoretical, all-platform, value. To find which backends	239	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	240	current system. To find which embeddable backends might be supported on
228	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for	241	the current system, you would need to look at C<ev_embeddable_backends ()
229	recommended ones.	242	& ev_supported_backends ()>, likewise for recommended ones.
230		243
231	See the description of C<ev_embed> watchers for more info.	244	See the description of C<ev_embed> watchers for more info.
232		245
233	=item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT]	246	=item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT]
234		247
…		…
288	...	301	...
289	ev_set_syserr_cb (fatal_error);	302	ev_set_syserr_cb (fatal_error);
290		303
291	=back	304	=back
292		305
293	=head1 FUNCTIONS CONTROLLING THE EVENT LOOP	306	=head1 FUNCTIONS CONTROLLING EVENT LOOPS
294		307
295	An event loop is described by a C<struct ev_loop *> (the C<struct>	308	An event loop is described by a C<struct ev_loop *> (the C<struct> is
296	is I<not> optional in this case, as there is also an C<ev_loop>	309	I<not> optional in this case unless libev 3 compatibility is disabled, as
297	I<function>).	310	libev 3 had an C<ev_loop> function colliding with the struct name).
298		311
299	The library knows two types of such loops, the I<default> loop, which	312	The library knows two types of such loops, the I<default> loop, which
300	supports signals and child events, and dynamically created loops which do	313	supports child process events, and dynamically created event loops which
301	not.	314	do not.
302		315
303	=over 4	316	=over 4
304		317
305	=item struct ev_loop *ev_default_loop (unsigned int flags)	318	=item struct ev_loop *ev_default_loop (unsigned int flags)
306		319
307	This will initialise the default event loop if it hasn't been initialised	320	This returns the "default" event loop object, which is what you should
308	yet and return it. If the default loop could not be initialised, returns	321	normally use when you just need "the event loop". Event loop objects and
309	false. If it already was initialised it simply returns it (and ignores the	322	the C<flags> parameter are described in more detail in the entry for
310	flags. If that is troubling you, check C<ev_backend ()> afterwards).	323	C<ev_loop_new>.
		324
		325	If the default loop is already initialised then this function simply
		326	returns it (and ignores the flags. If that is troubling you, check
		327	C<ev_backend ()> afterwards). Otherwise it will create it with the given
		328	flags, which should almost always be C<0>, unless the caller is also the
		329	one calling C<ev_run> or otherwise qualifies as "the main program".
311		330
312	If you don't know what event loop to use, use the one returned from this	331	If you don't know what event loop to use, use the one returned from this
313	function.	332	function (or via the C<EV_DEFAULT> macro).
314		333
315	Note that this function is I<not> thread-safe, so if you want to use it	334	Note that this function is I<not> thread-safe, so if you want to use it
316	from multiple threads, you have to lock (note also that this is unlikely,	335	from multiple threads, you have to employ some kind of mutex (note also
317	as loops cannot be shared easily between threads anyway).	336	that this case is unlikely, as loops cannot be shared easily between
		337	threads anyway).
318		338
319	The default loop is the only loop that can handle C<ev_signal> and	339	The default loop is the only loop that can handle C<ev_child> watchers,
320	C<ev_child> watchers, and to do this, it always registers a handler	340	and to do this, it always registers a handler for C<SIGCHLD>. If this is
321	for C<SIGCHLD>. If this is a problem for your application you can either	341	a problem for your application you can either create a dynamic loop with
322	create a dynamic loop with C<ev_loop_new> that doesn't do that, or you	342	C<ev_loop_new> which doesn't do that, or you can simply overwrite the
323	can simply overwrite the C<SIGCHLD> signal handler I<after> calling	343	C<SIGCHLD> signal handler I<after> calling C<ev_default_init>.
324	C<ev_default_init>.	344
		345	Example: This is the most typical usage.
		346
		347	if (!ev_default_loop (0))
		348	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
		349
		350	Example: Restrict libev to the select and poll backends, and do not allow
		351	environment settings to be taken into account:
		352
		353	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
		354
		355	=item struct ev_loop *ev_loop_new (unsigned int flags)
		356
		357	This will create and initialise a new event loop object. If the loop
		358	could not be initialised, returns false.
		359
		360	Note that this function I<is> thread-safe, and one common way to use
		361	libev with threads is indeed to create one loop per thread, and using the
		362	default loop in the "main" or "initial" thread.
325		363
326	The flags argument can be used to specify special behaviour or specific	364	The flags argument can be used to specify special behaviour or specific
327	backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>).	365	backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>).
328		366
329	The following flags are supported:	367	The following flags are supported:
…		…
344	useful to try out specific backends to test their performance, or to work	382	useful to try out specific backends to test their performance, or to work
345	around bugs.	383	around bugs.
346		384
347	=item C<EVFLAG_FORKCHECK>	385	=item C<EVFLAG_FORKCHECK>
348		386
349	Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after	387	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	388	make libev check for a fork in each iteration by enabling this flag.
351	enabling this flag.
352		389
353	This works by calling C<getpid ()> on every iteration of the loop,	390	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	391	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	392	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	393	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence
…		…
362	flag.	399	flag.
363		400
364	This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS>	401	This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS>
365	environment variable.	402	environment variable.
366		403
		404	=item C<EVFLAG_NOINOTIFY>
		405
		406	When this flag is specified, then libev will not attempt to use the
		407	I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and
		408	testing, this flag can be useful to conserve inotify file descriptors, as
		409	otherwise each loop using C<ev_stat> watchers consumes one inotify handle.
		410
		411	=item C<EVFLAG_SIGNALFD>
		412
		413	When this flag is specified, then libev will attempt to use the
		414	I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This API
		415	delivers signals synchronously, which makes it both faster and might make
		416	it possible to get the queued signal data. It can also simplify signal
		417	handling with threads, as long as you properly block signals in your
		418	threads that are not interested in handling them.
		419
		420	Signalfd will not be used by default as this changes your signal mask, and
		421	there are a lot of shoddy libraries and programs (glib's threadpool for
		422	example) that can't properly initialise their signal masks.
		423
367	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	424	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
368		425
369	This is your standard select(2) backend. Not I<completely> standard, as	426	This is your standard select(2) backend. Not I<completely> standard, as
370	libev tries to roll its own fd_set with no limits on the number of fds,	427	libev tries to roll its own fd_set with no limits on the number of fds,
371	but if that fails, expect a fairly low limit on the number of fds when	428	but if that fails, expect a fairly low limit on the number of fds when
…		…
394		451
395	This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and	452	This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and
396	C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>.	453	C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>.
397		454
398	=item C<EVBACKEND_EPOLL> (value 4, Linux)	455	=item C<EVBACKEND_EPOLL> (value 4, Linux)
		456
		457	Use the linux-specific epoll(7) interface (for both pre- and post-2.6.9
		458	kernels).
399		459
400	For few fds, this backend is a bit little slower than poll and select,	460	For few fds, this backend is a bit little slower than poll and select,
401	but it scales phenomenally better. While poll and select usually scale	461	but it scales phenomenally better. While poll and select usually scale
402	like O(total_fds) where n is the total number of fds (or the highest fd),	462	like O(total_fds) where n is the total number of fds (or the highest fd),
403	epoll scales either O(1) or O(active_fds).	463	epoll scales either O(1) or O(active_fds).
…		…
415	of course I<doesn't>, and epoll just loves to report events for totally	475	of course I<doesn't>, and epoll just loves to report events for totally
416	I<different> file descriptors (even already closed ones, so one cannot	476	I<different> file descriptors (even already closed ones, so one cannot
417	even remove them from the set) than registered in the set (especially	477	even remove them from the set) than registered in the set (especially
418	on SMP systems). Libev tries to counter these spurious notifications by	478	on SMP systems). Libev tries to counter these spurious notifications by
419	employing an additional generation counter and comparing that against the	479	employing an additional generation counter and comparing that against the
420	events to filter out spurious ones, recreating the set when required.	480	events to filter out spurious ones, recreating the set when required. Last
		481	not least, it also refuses to work with some file descriptors which work
		482	perfectly fine with C<select> (files, many character devices...).
421		483
422	While stopping, setting and starting an I/O watcher in the same iteration	484	While stopping, setting and starting an I/O watcher in the same iteration
423	will result in some caching, there is still a system call per such	485	will result in some caching, there is still a system call per such
424	incident (because the same I<file descriptor> could point to a different	486	incident (because the same I<file descriptor> could point to a different
425	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed	487	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed
…		…
518		580
519	It is definitely not recommended to use this flag.	581	It is definitely not recommended to use this flag.
520		582
521	=back	583	=back
522		584
523	If one or more of these are or'ed into the flags value, then only these	585	If one or more of the backend flags are or'ed into the flags value,
524	backends will be tried (in the reverse order as listed here). If none are	586	then only these backends will be tried (in the reverse order as listed
525	specified, all backends in C<ev_recommended_backends ()> will be tried.	587	here). If none are specified, all backends in C<ev_recommended_backends
526		588	()> will be tried.
527	Example: This is the most typical usage.
528
529	if (!ev_default_loop (0))
530	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
531
532	Example: Restrict libev to the select and poll backends, and do not allow
533	environment settings to be taken into account:
534
535	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
536
537	Example: Use whatever libev has to offer, but make sure that kqueue is
538	used if available (warning, breaks stuff, best use only with your own
539	private event loop and only if you know the OS supports your types of
540	fds):
541
542	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
543
544	=item struct ev_loop *ev_loop_new (unsigned int flags)
545
546	Similar to C<ev_default_loop>, but always creates a new event loop that is
547	always distinct from the default loop. Unlike the default loop, it cannot
548	handle signal and child watchers, and attempts to do so will be greeted by
549	undefined behaviour (or a failed assertion if assertions are enabled).
550
551	Note that this function I<is> thread-safe, and the recommended way to use
552	libev with threads is indeed to create one loop per thread, and using the
553	default loop in the "main" or "initial" thread.
554		589
555	Example: Try to create a event loop that uses epoll and nothing else.	590	Example: Try to create a event loop that uses epoll and nothing else.
556		591
557	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	592	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
558	if (!epoller)	593	if (!epoller)
559	fatal ("no epoll found here, maybe it hides under your chair");	594	fatal ("no epoll found here, maybe it hides under your chair");
560		595
		596	Example: Use whatever libev has to offer, but make sure that kqueue is
		597	used if available.
		598
		599	struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE);
		600
561	=item ev_default_destroy ()	601	=item ev_loop_destroy (loop)
562		602
563	Destroys the default loop again (frees all memory and kernel state	603	Destroys an event loop object (frees all memory and kernel state
564	etc.). None of the active event watchers will be stopped in the normal	604	etc.). None of the active event watchers will be stopped in the normal
565	sense, so e.g. C<ev_is_active> might still return true. It is your	605	sense, so e.g. C<ev_is_active> might still return true. It is your
566	responsibility to either stop all watchers cleanly yourself I<before>	606	responsibility to either stop all watchers cleanly yourself I<before>
567	calling this function, or cope with the fact afterwards (which is usually	607	calling this function, or cope with the fact afterwards (which is usually
568	the easiest thing, you can just ignore the watchers and/or C<free ()> them	608	the easiest thing, you can just ignore the watchers and/or C<free ()> them
…		…
570		610
571	Note that certain global state, such as signal state (and installed signal	611	Note that certain global state, such as signal state (and installed signal
572	handlers), will not be freed by this function, and related watchers (such	612	handlers), will not be freed by this function, and related watchers (such
573	as signal and child watchers) would need to be stopped manually.	613	as signal and child watchers) would need to be stopped manually.
574		614
575	In general it is not advisable to call this function except in the	615	This function is normally used on loop objects allocated by
576	rare occasion where you really need to free e.g. the signal handling	616	C<ev_loop_new>, but it can also be used on the default loop returned by
		617	C<ev_default_loop>, in which case it is not thread-safe.
		618
		619	Note that it is not advisable to call this function on the default loop
		620	except in the rare occasion where you really need to free it's resources.
577	pipe fds. If you need dynamically allocated loops it is better to use	621	If you need dynamically allocated loops it is better to use C<ev_loop_new>
578	C<ev_loop_new> and C<ev_loop_destroy>).	622	and C<ev_loop_destroy>.
579		623
580	=item ev_loop_destroy (loop)	624	=item ev_loop_fork (loop)
581		625
582	Like C<ev_default_destroy>, but destroys an event loop created by an
583	earlier call to C<ev_loop_new>.
584
585	=item ev_default_fork ()
586
587	This function sets a flag that causes subsequent C<ev_loop> iterations	626	This function sets a flag that causes subsequent C<ev_run> iterations to
588	to reinitialise the kernel state for backends that have one. Despite the	627	reinitialise the kernel state for backends that have one. Despite the
589	name, you can call it anytime, but it makes most sense after forking, in	628	name, you can call it anytime, but it makes most sense after forking, in
590	the child process (or both child and parent, but that again makes little	629	the child process. You I<must> call it (or use C<EVFLAG_FORKCHECK>) in the
591	sense). You I<must> call it in the child before using any of the libev	630	child before resuming or calling C<ev_run>.
592	functions, and it will only take effect at the next C<ev_loop> iteration.	631
		632	Again, you I<have> to call it on I<any> loop that you want to re-use after
		633	a fork, I<even if you do not plan to use the loop in the parent>. This is
		634	because some kernel interfaces *cough* I<kqueue> *cough* do funny things
		635	during fork.
593		636
594	On the other hand, you only need to call this function in the child	637	On the other hand, you only need to call this function in the child
595	process if and only if you want to use the event library in the child. If	638	process if and only if you want to use the event loop in the child. If
596	you just fork+exec, you don't have to call it at all.	639	you just fork+exec or create a new loop in the child, you don't have to
		640	call it at all (in fact, C<epoll> is so badly broken that it makes a
		641	difference, but libev will usually detect this case on its own and do a
		642	costly reset of the backend).
597		643
598	The function itself is quite fast and it's usually not a problem to call	644	The function itself is quite fast and it's usually not a problem to call
599	it just in case after a fork. To make this easy, the function will fit in	645	it just in case after a fork.
600	quite nicely into a call to C<pthread_atfork>:
601		646
		647	Example: Automate calling C<ev_loop_fork> on the default loop when
		648	using pthreads.
		649
		650	static void
		651	post_fork_child (void)
		652	{
		653	ev_loop_fork (EV_DEFAULT);
		654	}
		655
		656	...
602	pthread_atfork (0, 0, ev_default_fork);	657	pthread_atfork (0, 0, post_fork_child);
603
604	=item ev_loop_fork (loop)
605
606	Like C<ev_default_fork>, but acts on an event loop created by
607	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
608	after fork that you want to re-use in the child, and how you do this is
609	entirely your own problem.
610		658
611	=item int ev_is_default_loop (loop)	659	=item int ev_is_default_loop (loop)
612		660
613	Returns true when the given loop is, in fact, the default loop, and false	661	Returns true when the given loop is, in fact, the default loop, and false
614	otherwise.	662	otherwise.
615		663
616	=item unsigned int ev_loop_count (loop)	664	=item unsigned int ev_iteration (loop)
617		665
618	Returns the count of loop iterations for the loop, which is identical to	666	Returns the current iteration count for the event loop, which is identical
619	the number of times libev did poll for new events. It starts at C<0> and	667	to the number of times libev did poll for new events. It starts at C<0>
620	happily wraps around with enough iterations.	668	and happily wraps around with enough iterations.
621		669
622	This value can sometimes be useful as a generation counter of sorts (it	670	This value can sometimes be useful as a generation counter of sorts (it
623	"ticks" the number of loop iterations), as it roughly corresponds with	671	"ticks" the number of loop iterations), as it roughly corresponds with
624	C<ev_prepare> and C<ev_check> calls.	672	C<ev_prepare> and C<ev_check> calls - and is incremented between the
		673	prepare and check phases.
625		674
626	=item unsigned int ev_loop_depth (loop)	675	=item unsigned int ev_depth (loop)
627		676
628	Returns the number of times C<ev_loop> was entered minus the number of	677	Returns the number of times C<ev_run> was entered minus the number of
629	times C<ev_loop> was exited, in other words, the recursion depth.	678	times C<ev_run> was exited, in other words, the recursion depth.
630		679
631	Outside C<ev_loop>, this number is zero. In a callback, this number is	680	Outside C<ev_run>, this number is zero. In a callback, this number is
632	C<1>, unless C<ev_loop> was invoked recursively (or from another thread),	681	C<1>, unless C<ev_run> was invoked recursively (or from another thread),
633	in which case it is higher.	682	in which case it is higher.
634		683
635	Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread	684	Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread
636	etc.), doesn't count as exit.	685	etc.), doesn't count as "exit" - consider this as a hint to avoid such
		686	ungentleman-like behaviour unless it's really convenient.
637		687
638	=item unsigned int ev_backend (loop)	688	=item unsigned int ev_backend (loop)
639		689
640	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	690	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
641	use.	691	use.
…		…
650		700
651	=item ev_now_update (loop)	701	=item ev_now_update (loop)
652		702
653	Establishes the current time by querying the kernel, updating the time	703	Establishes the current time by querying the kernel, updating the time
654	returned by C<ev_now ()> in the progress. This is a costly operation and	704	returned by C<ev_now ()> in the progress. This is a costly operation and
655	is usually done automatically within C<ev_loop ()>.	705	is usually done automatically within C<ev_run ()>.
656		706
657	This function is rarely useful, but when some event callback runs for a	707	This function is rarely useful, but when some event callback runs for a
658	very long time without entering the event loop, updating libev's idea of	708	very long time without entering the event loop, updating libev's idea of
659	the current time is a good idea.	709	the current time is a good idea.
660		710
…		…
662		712
663	=item ev_suspend (loop)	713	=item ev_suspend (loop)
664		714
665	=item ev_resume (loop)	715	=item ev_resume (loop)
666		716
667	These two functions suspend and resume a loop, for use when the loop is	717	These two functions suspend and resume an event loop, for use when the
668	not used for a while and timeouts should not be processed.	718	loop is not used for a while and timeouts should not be processed.
669		719
670	A typical use case would be an interactive program such as a game: When	720	A typical use case would be an interactive program such as a game: When
671	the user presses C<^Z> to suspend the game and resumes it an hour later it	721	the user presses C<^Z> to suspend the game and resumes it an hour later it
672	would be best to handle timeouts as if no time had actually passed while	722	would be best to handle timeouts as if no time had actually passed while
673	the program was suspended. This can be achieved by calling C<ev_suspend>	723	the program was suspended. This can be achieved by calling C<ev_suspend>
…		…
675	C<ev_resume> directly afterwards to resume timer processing.	725	C<ev_resume> directly afterwards to resume timer processing.
676		726
677	Effectively, all C<ev_timer> watchers will be delayed by the time spend	727	Effectively, all C<ev_timer> watchers will be delayed by the time spend
678	between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers	728	between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers
679	will be rescheduled (that is, they will lose any events that would have	729	will be rescheduled (that is, they will lose any events that would have
680	occured while suspended).	730	occurred while suspended).
681		731
682	After calling C<ev_suspend> you B<must not> call I<any> function on the	732	After calling C<ev_suspend> you B<must not> call I<any> function on the
683	given loop other than C<ev_resume>, and you B<must not> call C<ev_resume>	733	given loop other than C<ev_resume>, and you B<must not> call C<ev_resume>
684	without a previous call to C<ev_suspend>.	734	without a previous call to C<ev_suspend>.
685		735
686	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the	736	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the
687	event loop time (see C<ev_now_update>).	737	event loop time (see C<ev_now_update>).
688		738
689	=item ev_loop (loop, int flags)	739	=item ev_run (loop, int flags)
690		740
691	Finally, this is it, the event handler. This function usually is called	741	Finally, this is it, the event handler. This function usually is called
692	after you initialised all your watchers and you want to start handling	742	after you have initialised all your watchers and you want to start
693	events.	743	handling events. It will ask the operating system for any new events, call
		744	the watcher callbacks, an then repeat the whole process indefinitely: This
		745	is why event loops are called I<loops>.
694		746
695	If the flags argument is specified as C<0>, it will not return until	747	If the flags argument is specified as C<0>, it will keep handling events
696	either no event watchers are active anymore or C<ev_unloop> was called.	748	until either no event watchers are active anymore or C<ev_break> was
		749	called.
697		750
698	Please note that an explicit C<ev_unloop> is usually better than	751	Please note that an explicit C<ev_break> is usually better than
699	relying on all watchers to be stopped when deciding when a program has	752	relying on all watchers to be stopped when deciding when a program has
700	finished (especially in interactive programs), but having a program	753	finished (especially in interactive programs), but having a program
701	that automatically loops as long as it has to and no longer by virtue	754	that automatically loops as long as it has to and no longer by virtue
702	of relying on its watchers stopping correctly, that is truly a thing of	755	of relying on its watchers stopping correctly, that is truly a thing of
703	beauty.	756	beauty.
704		757
705	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle	758	A flags value of C<EVRUN_NOWAIT> will look for new events, will handle
706	those events and any already outstanding ones, but will not block your	759	those events and any already outstanding ones, but will not wait and
707	process in case there are no events and will return after one iteration of	760	block your process in case there are no events and will return after one
708	the loop.	761	iteration of the loop. This is sometimes useful to poll and handle new
		762	events while doing lengthy calculations, to keep the program responsive.
709		763
710	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if	764	A flags value of C<EVRUN_ONCE> will look for new events (waiting if
711	necessary) and will handle those and any already outstanding ones. It	765	necessary) and will handle those and any already outstanding ones. It
712	will block your process until at least one new event arrives (which could	766	will block your process until at least one new event arrives (which could
713	be an event internal to libev itself, so there is no guarantee that a	767	be an event internal to libev itself, so there is no guarantee that a
714	user-registered callback will be called), and will return after one	768	user-registered callback will be called), and will return after one
715	iteration of the loop.	769	iteration of the loop.
716		770
717	This is useful if you are waiting for some external event in conjunction	771	This is useful if you are waiting for some external event in conjunction
718	with something not expressible using other libev watchers (i.e. "roll your	772	with something not expressible using other libev watchers (i.e. "roll your
719	own C<ev_loop>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is	773	own C<ev_run>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is
720	usually a better approach for this kind of thing.	774	usually a better approach for this kind of thing.
721		775
722	Here are the gory details of what C<ev_loop> does:	776	Here are the gory details of what C<ev_run> does:
723		777
		778	- Increment loop depth.
		779	- Reset the ev_break status.
724	- Before the first iteration, call any pending watchers.	780	- Before the first iteration, call any pending watchers.
		781	LOOP:
725	* If EVFLAG_FORKCHECK was used, check for a fork.	782	- If EVFLAG_FORKCHECK was used, check for a fork.
726	- If a fork was detected (by any means), queue and call all fork watchers.	783	- If a fork was detected (by any means), queue and call all fork watchers.
727	- Queue and call all prepare watchers.	784	- Queue and call all prepare watchers.
		785	- If ev_break was called, goto FINISH.
728	- If we have been forked, detach and recreate the kernel state	786	- If we have been forked, detach and recreate the kernel state
729	as to not disturb the other process.	787	as to not disturb the other process.
730	- Update the kernel state with all outstanding changes.	788	- Update the kernel state with all outstanding changes.
731	- Update the "event loop time" (ev_now ()).	789	- Update the "event loop time" (ev_now ()).
732	- Calculate for how long to sleep or block, if at all	790	- Calculate for how long to sleep or block, if at all
733	(active idle watchers, EVLOOP_NONBLOCK or not having	791	(active idle watchers, EVRUN_NOWAIT or not having
734	any active watchers at all will result in not sleeping).	792	any active watchers at all will result in not sleeping).
735	- Sleep if the I/O and timer collect interval say so.	793	- Sleep if the I/O and timer collect interval say so.
		794	- Increment loop iteration counter.
736	- Block the process, waiting for any events.	795	- Block the process, waiting for any events.
737	- Queue all outstanding I/O (fd) events.	796	- Queue all outstanding I/O (fd) events.
738	- Update the "event loop time" (ev_now ()), and do time jump adjustments.	797	- Update the "event loop time" (ev_now ()), and do time jump adjustments.
739	- Queue all expired timers.	798	- Queue all expired timers.
740	- Queue all expired periodics.	799	- Queue all expired periodics.
741	- Unless any events are pending now, queue all idle watchers.	800	- Queue all idle watchers with priority higher than that of pending events.
742	- Queue all check watchers.	801	- Queue all check watchers.
743	- Call all queued watchers in reverse order (i.e. check watchers first).	802	- Call all queued watchers in reverse order (i.e. check watchers first).
744	Signals and child watchers are implemented as I/O watchers, and will	803	Signals and child watchers are implemented as I/O watchers, and will
745	be handled here by queueing them when their watcher gets executed.	804	be handled here by queueing them when their watcher gets executed.
746	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	805	- If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT
747	were used, or there are no active watchers, return, otherwise	806	were used, or there are no active watchers, goto FINISH, otherwise
748	continue with step *.	807	continue with step LOOP.
		808	FINISH:
		809	- Reset the ev_break status iff it was EVBREAK_ONE.
		810	- Decrement the loop depth.
		811	- Return.
749		812
750	Example: Queue some jobs and then loop until no events are outstanding	813	Example: Queue some jobs and then loop until no events are outstanding
751	anymore.	814	anymore.
752		815
753	... queue jobs here, make sure they register event watchers as long	816	... queue jobs here, make sure they register event watchers as long
754	... as they still have work to do (even an idle watcher will do..)	817	... as they still have work to do (even an idle watcher will do..)
755	ev_loop (my_loop, 0);	818	ev_run (my_loop, 0);
756	... jobs done or somebody called unloop. yeah!	819	... jobs done or somebody called unloop. yeah!
757		820
758	=item ev_unloop (loop, how)	821	=item ev_break (loop, how)
759		822
760	Can be used to make a call to C<ev_loop> return early (but only after it	823	Can be used to make a call to C<ev_run> return early (but only after it
761	has processed all outstanding events). The C<how> argument must be either	824	has processed all outstanding events). The C<how> argument must be either
762	C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or	825	C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or
763	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.	826	C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return.
764		827
765	This "unloop state" will be cleared when entering C<ev_loop> again.	828	This "unloop state" will be cleared when entering C<ev_run> again.
766		829
767	It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls.	830	It is safe to call C<ev_break> from outside any C<ev_run> calls. ##TODO##
768		831
769	=item ev_ref (loop)	832	=item ev_ref (loop)
770		833
771	=item ev_unref (loop)	834	=item ev_unref (loop)
772		835
773	Ref/unref can be used to add or remove a reference count on the event	836	Ref/unref can be used to add or remove a reference count on the event
774	loop: Every watcher keeps one reference, and as long as the reference	837	loop: Every watcher keeps one reference, and as long as the reference
775	count is nonzero, C<ev_loop> will not return on its own.	838	count is nonzero, C<ev_run> will not return on its own.
776		839
777	If you have a watcher you never unregister that should not keep C<ev_loop>	840	This is useful when you have a watcher that you never intend to
778	from returning, call ev_unref() after starting, and ev_ref() before	841	unregister, but that nevertheless should not keep C<ev_run> from
		842	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>
779	stopping it.	843	before stopping it.
780		844
781	As an example, libev itself uses this for its internal signal pipe: It	845	As an example, libev itself uses this for its internal signal pipe: It
782	is not visible to the libev user and should not keep C<ev_loop> from	846	is not visible to the libev user and should not keep C<ev_run> from
783	exiting if no event watchers registered by it are active. It is also an	847	exiting if no event watchers registered by it are active. It is also an
784	excellent way to do this for generic recurring timers or from within	848	excellent way to do this for generic recurring timers or from within
785	third-party libraries. Just remember to I<unref after start> and I<ref	849	third-party libraries. Just remember to I<unref after start> and I<ref
786	before stop> (but only if the watcher wasn't active before, or was active	850	before stop> (but only if the watcher wasn't active before, or was active
787	before, respectively. Note also that libev might stop watchers itself	851	before, respectively. Note also that libev might stop watchers itself
788	(e.g. non-repeating timers) in which case you have to C<ev_ref>	852	(e.g. non-repeating timers) in which case you have to C<ev_ref>
789	in the callback).	853	in the callback).
790		854
791	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	855	Example: Create a signal watcher, but keep it from keeping C<ev_run>
792	running when nothing else is active.	856	running when nothing else is active.
793		857
794	ev_signal exitsig;	858	ev_signal exitsig;
795	ev_signal_init (&exitsig, sig_cb, SIGINT);	859	ev_signal_init (&exitsig, sig_cb, SIGINT);
796	ev_signal_start (loop, &exitsig);	860	ev_signal_start (loop, &exitsig);
…		…
841	usually doesn't make much sense to set it to a lower value than C<0.01>,	905	usually doesn't make much sense to set it to a lower value than C<0.01>,
842	as this approaches the timing granularity of most systems. Note that if	906	as this approaches the timing granularity of most systems. Note that if
843	you do transactions with the outside world and you can't increase the	907	you do transactions with the outside world and you can't increase the
844	parallelity, then this setting will limit your transaction rate (if you	908	parallelity, then this setting will limit your transaction rate (if you
845	need to poll once per transaction and the I/O collect interval is 0.01,	909	need to poll once per transaction and the I/O collect interval is 0.01,
846	then you can't do more than 100 transations per second).	910	then you can't do more than 100 transactions per second).
847		911
848	Setting the I<timeout collect interval> can improve the opportunity for	912	Setting the I<timeout collect interval> can improve the opportunity for
849	saving power, as the program will "bundle" timer callback invocations that	913	saving power, as the program will "bundle" timer callback invocations that
850	are "near" in time together, by delaying some, thus reducing the number of	914	are "near" in time together, by delaying some, thus reducing the number of
851	times the process sleeps and wakes up again. Another useful technique to	915	times the process sleeps and wakes up again. Another useful technique to
…		…
859	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);	923	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);
860		924
861	=item ev_invoke_pending (loop)	925	=item ev_invoke_pending (loop)
862		926
863	This call will simply invoke all pending watchers while resetting their	927	This call will simply invoke all pending watchers while resetting their
864	pending state. Normally, C<ev_loop> does this automatically when required,	928	pending state. Normally, C<ev_run> does this automatically when required,
865	but when overriding the invoke callback this call comes handy.	929	but when overriding the invoke callback this call comes handy. This
		930	function can be invoked from a watcher - this can be useful for example
		931	when you want to do some lengthy calculation and want to pass further
		932	event handling to another thread (you still have to make sure only one
		933	thread executes within C<ev_invoke_pending> or C<ev_run> of course).
		934
		935	=item int ev_pending_count (loop)
		936
		937	Returns the number of pending watchers - zero indicates that no watchers
		938	are pending.
866		939
867	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))	940	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))
868		941
869	This overrides the invoke pending functionality of the loop: Instead of	942	This overrides the invoke pending functionality of the loop: Instead of
870	invoking all pending watchers when there are any, C<ev_loop> will call	943	invoking all pending watchers when there are any, C<ev_run> will call
871	this callback instead. This is useful, for example, when you want to	944	this callback instead. This is useful, for example, when you want to
872	invoke the actual watchers inside another context (another thread etc.).	945	invoke the actual watchers inside another context (another thread etc.).
873		946
874	If you want to reset the callback, use C<ev_invoke_pending> as new	947	If you want to reset the callback, use C<ev_invoke_pending> as new
875	callback.	948	callback.
…		…
878		951
879	Sometimes you want to share the same loop between multiple threads. This	952	Sometimes you want to share the same loop between multiple threads. This
880	can be done relatively simply by putting mutex_lock/unlock calls around	953	can be done relatively simply by putting mutex_lock/unlock calls around
881	each call to a libev function.	954	each call to a libev function.
882		955
883	However, C<ev_loop> can run an indefinite time, so it is not feasible to	956	However, C<ev_run> can run an indefinite time, so it is not feasible
884	wait for it to return. One way around this is to wake up the loop via	957	to wait for it to return. One way around this is to wake up the event
885	C<ev_unloop> and C<av_async_send>, another way is to set these I<release>	958	loop via C<ev_break> and C<av_async_send>, another way is to set these
886	and I<acquire> callbacks on the loop.	959	I<release> and I<acquire> callbacks on the loop.
887		960
888	When set, then C<release> will be called just before the thread is	961	When set, then C<release> will be called just before the thread is
889	suspended waiting for new events, and C<acquire> is called just	962	suspended waiting for new events, and C<acquire> is called just
890	afterwards.	963	afterwards.
891		964
892	Ideally, C<release> will just call your mutex_unlock function, and	965	Ideally, C<release> will just call your mutex_unlock function, and
893	C<acquire> will just call the mutex_lock function again.	966	C<acquire> will just call the mutex_lock function again.
		967
		968	While event loop modifications are allowed between invocations of
		969	C<release> and C<acquire> (that's their only purpose after all), no
		970	modifications done will affect the event loop, i.e. adding watchers will
		971	have no effect on the set of file descriptors being watched, or the time
		972	waited. Use an C<ev_async> watcher to wake up C<ev_run> when you want it
		973	to take note of any changes you made.
		974
		975	In theory, threads executing C<ev_run> will be async-cancel safe between
		976	invocations of C<release> and C<acquire>.
		977
		978	See also the locking example in the C<THREADS> section later in this
		979	document.
894		980
895	=item ev_set_userdata (loop, void *data)	981	=item ev_set_userdata (loop, void *data)
896		982
897	=item ev_userdata (loop)	983	=item ev_userdata (loop)
898		984
…		…
903	These two functions can be used to associate arbitrary data with a loop,	989	These two functions can be used to associate arbitrary data with a loop,
904	and are intended solely for the C<invoke_pending_cb>, C<release> and	990	and are intended solely for the C<invoke_pending_cb>, C<release> and
905	C<acquire> callbacks described above, but of course can be (ab-)used for	991	C<acquire> callbacks described above, but of course can be (ab-)used for
906	any other purpose as well.	992	any other purpose as well.
907		993
908	=item ev_loop_verify (loop)	994	=item ev_verify (loop)
909		995
910	This function only does something when C<EV_VERIFY> support has been	996	This function only does something when C<EV_VERIFY> support has been
911	compiled in, which is the default for non-minimal builds. It tries to go	997	compiled in, which is the default for non-minimal builds. It tries to go
912	through all internal structures and checks them for validity. If anything	998	through all internal structures and checks them for validity. If anything
913	is found to be inconsistent, it will print an error message to standard	999	is found to be inconsistent, it will print an error message to standard
…		…
924		1010
925	In the following description, uppercase C<TYPE> in names stands for the	1011	In the following description, uppercase C<TYPE> in names stands for the
926	watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer	1012	watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer
927	watchers and C<ev_io_start> for I/O watchers.	1013	watchers and C<ev_io_start> for I/O watchers.
928		1014
929	A watcher is a structure that you create and register to record your	1015	A watcher is an opaque structure that you allocate and register to record
930	interest in some event. For instance, if you want to wait for STDIN to	1016	your interest in some event. To make a concrete example, imagine you want
931	become readable, you would create an C<ev_io> watcher for that:	1017	to wait for STDIN to become readable, you would create an C<ev_io> watcher
		1018	for that:
932		1019
933	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)	1020	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)
934	{	1021	{
935	ev_io_stop (w);	1022	ev_io_stop (w);
936	ev_unloop (loop, EVUNLOOP_ALL);	1023	ev_break (loop, EVBREAK_ALL);
937	}	1024	}
938		1025
939	struct ev_loop *loop = ev_default_loop (0);	1026	struct ev_loop *loop = ev_default_loop (0);
940		1027
941	ev_io stdin_watcher;	1028	ev_io stdin_watcher;
942		1029
943	ev_init (&stdin_watcher, my_cb);	1030	ev_init (&stdin_watcher, my_cb);
944	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	1031	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
945	ev_io_start (loop, &stdin_watcher);	1032	ev_io_start (loop, &stdin_watcher);
946		1033
947	ev_loop (loop, 0);	1034	ev_run (loop, 0);
948		1035
949	As you can see, you are responsible for allocating the memory for your	1036	As you can see, you are responsible for allocating the memory for your
950	watcher structures (and it is I<usually> a bad idea to do this on the	1037	watcher structures (and it is I<usually> a bad idea to do this on the
951	stack).	1038	stack).
952		1039
953	Each watcher has an associated watcher structure (called C<struct ev_TYPE>	1040	Each watcher has an associated watcher structure (called C<struct ev_TYPE>
954	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).	1041	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).
955		1042
956	Each watcher structure must be initialised by a call to C<ev_init	1043	Each watcher structure must be initialised by a call to C<ev_init (watcher
957	(watcher *, callback)>, which expects a callback to be provided. This	1044	*, callback)>, which expects a callback to be provided. This callback is
958	callback gets invoked each time the event occurs (or, in the case of I/O	1045	invoked each time the event occurs (or, in the case of I/O watchers, each
959	watchers, each time the event loop detects that the file descriptor given	1046	time the event loop detects that the file descriptor given is readable
960	is readable and/or writable).	1047	and/or writable).
961		1048
962	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>	1049	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>
963	macro to configure it, with arguments specific to the watcher type. There	1050	macro to configure it, with arguments specific to the watcher type. There
964	is also a macro to combine initialisation and setting in one call: C<<	1051	is also a macro to combine initialisation and setting in one call: C<<
965	ev_TYPE_init (watcher *, callback, ...) >>.	1052	ev_TYPE_init (watcher *, callback, ...) >>.
…		…
988	=item C<EV_WRITE>	1075	=item C<EV_WRITE>
989		1076
990	The file descriptor in the C<ev_io> watcher has become readable and/or	1077	The file descriptor in the C<ev_io> watcher has become readable and/or
991	writable.	1078	writable.
992		1079
993	=item C<EV_TIMEOUT>	1080	=item C<EV_TIMER>
994		1081
995	The C<ev_timer> watcher has timed out.	1082	The C<ev_timer> watcher has timed out.
996		1083
997	=item C<EV_PERIODIC>	1084	=item C<EV_PERIODIC>
998		1085
…		…
1016		1103
1017	=item C<EV_PREPARE>	1104	=item C<EV_PREPARE>
1018		1105
1019	=item C<EV_CHECK>	1106	=item C<EV_CHECK>
1020		1107
1021	All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts	1108	All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts
1022	to gather new events, and all C<ev_check> watchers are invoked just after	1109	to gather new events, and all C<ev_check> watchers are invoked just after
1023	C<ev_loop> has gathered them, but before it invokes any callbacks for any	1110	C<ev_run> has gathered them, but before it invokes any callbacks for any
1024	received events. Callbacks of both watcher types can start and stop as	1111	received events. Callbacks of both watcher types can start and stop as
1025	many watchers as they want, and all of them will be taken into account	1112	many watchers as they want, and all of them will be taken into account
1026	(for example, a C<ev_prepare> watcher might start an idle watcher to keep	1113	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
1027	C<ev_loop> from blocking).	1114	C<ev_run> from blocking).
1028		1115
1029	=item C<EV_EMBED>	1116	=item C<EV_EMBED>
1030		1117
1031	The embedded event loop specified in the C<ev_embed> watcher needs attention.	1118	The embedded event loop specified in the C<ev_embed> watcher needs attention.
1032		1119
1033	=item C<EV_FORK>	1120	=item C<EV_FORK>
1034		1121
1035	The event loop has been resumed in the child process after fork (see	1122	The event loop has been resumed in the child process after fork (see
1036	C<ev_fork>).	1123	C<ev_fork>).
		1124
		1125	=item C<EV_CLEANUP>
		1126
		1127	The event loop is about to be destroyed (see C<ev_cleanup>).
1037		1128
1038	=item C<EV_ASYNC>	1129	=item C<EV_ASYNC>
1039		1130
1040	The given async watcher has been asynchronously notified (see C<ev_async>).	1131	The given async watcher has been asynchronously notified (see C<ev_async>).
1041		1132
…		…
1063	programs, though, as the fd could already be closed and reused for another	1154	programs, though, as the fd could already be closed and reused for another
1064	thing, so beware.	1155	thing, so beware.
1065		1156
1066	=back	1157	=back
1067		1158
		1159	=head2 WATCHER STATES
		1160
		1161	There are various watcher states mentioned throughout this manual -
		1162	active, pending and so on. In this section these states and the rules to
		1163	transition between them will be described in more detail - and while these
		1164	rules might look complicated, they usually do "the right thing".
		1165
		1166	=over 4
		1167
		1168	=item initialiased
		1169
		1170	Before a watcher can be registered with the event looop it has to be
		1171	initialised. This can be done with a call to C<ev_TYPE_init>, or calls to
		1172	C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function.
		1173
		1174	In this state it is simply some block of memory that is suitable for use
		1175	in an event loop. It can be moved around, freed, reused etc. at will.
		1176
		1177	=item started/running/active
		1178
		1179	Once a watcher has been started with a call to C<ev_TYPE_start> it becomes
		1180	property of the event loop, and is actively waiting for events. While in
		1181	this state it cannot be accessed (except in a few documented ways), moved,
		1182	freed or anything else - the only legal thing is to keep a pointer to it,
		1183	and call libev functions on it that are documented to work on active watchers.
		1184
		1185	=item pending
		1186
		1187	If a watcher is active and libev determines that an event it is interested
		1188	in has occurred (such as a timer expiring), it will become pending. It will
		1189	stay in this pending state until either it is stopped or its callback is
		1190	about to be invoked, so it is not normally pending inside the watcher
		1191	callback.
		1192
		1193	The watcher might or might not be active while it is pending (for example,
		1194	an expired non-repeating timer can be pending but no longer active). If it
		1195	is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>),
		1196	but it is still property of the event loop at this time, so cannot be
		1197	moved, freed or reused. And if it is active the rules described in the
		1198	previous item still apply.
		1199
		1200	It is also possible to feed an event on a watcher that is not active (e.g.
		1201	via C<ev_feed_event>), in which case it becomes pending without being
		1202	active.
		1203
		1204	=item stopped
		1205
		1206	A watcher can be stopped implicitly by libev (in which case it might still
		1207	be pending), or explicitly by calling its C<ev_TYPE_stop> function. The
		1208	latter will clear any pending state the watcher might be in, regardless
		1209	of whether it was active or not, so stopping a watcher explicitly before
		1210	freeing it is often a good idea.
		1211
		1212	While stopped (and not pending) the watcher is essentially in the
		1213	initialised state, that is it can be reused, moved, modified in any way
		1214	you wish.
		1215
		1216	=back
		1217
1068	=head2 GENERIC WATCHER FUNCTIONS	1218	=head2 GENERIC WATCHER FUNCTIONS
1069		1219
1070	=over 4	1220	=over 4
1071		1221
1072	=item C<ev_init> (ev_TYPE *watcher, callback)	1222	=item C<ev_init> (ev_TYPE *watcher, callback)
…		…
1088		1238
1089	ev_io w;	1239	ev_io w;
1090	ev_init (&w, my_cb);	1240	ev_init (&w, my_cb);
1091	ev_io_set (&w, STDIN_FILENO, EV_READ);	1241	ev_io_set (&w, STDIN_FILENO, EV_READ);
1092		1242
1093	=item C<ev_TYPE_set> (ev_TYPE *, [args])	1243	=item C<ev_TYPE_set> (ev_TYPE *watcher, [args])
1094		1244
1095	This macro initialises the type-specific parts of a watcher. You need to	1245	This macro initialises the type-specific parts of a watcher. You need to
1096	call C<ev_init> at least once before you call this macro, but you can	1246	call C<ev_init> at least once before you call this macro, but you can
1097	call C<ev_TYPE_set> any number of times. You must not, however, call this	1247	call C<ev_TYPE_set> any number of times. You must not, however, call this
1098	macro on a watcher that is active (it can be pending, however, which is a	1248	macro on a watcher that is active (it can be pending, however, which is a
…		…
1111		1261
1112	Example: Initialise and set an C<ev_io> watcher in one step.	1262	Example: Initialise and set an C<ev_io> watcher in one step.
1113		1263
1114	ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ);	1264	ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ);
1115		1265
1116	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)	1266	=item C<ev_TYPE_start> (loop, ev_TYPE *watcher)
1117		1267
1118	Starts (activates) the given watcher. Only active watchers will receive	1268	Starts (activates) the given watcher. Only active watchers will receive
1119	events. If the watcher is already active nothing will happen.	1269	events. If the watcher is already active nothing will happen.
1120		1270
1121	Example: Start the C<ev_io> watcher that is being abused as example in this	1271	Example: Start the C<ev_io> watcher that is being abused as example in this
1122	whole section.	1272	whole section.
1123		1273
1124	ev_io_start (EV_DEFAULT_UC, &w);	1274	ev_io_start (EV_DEFAULT_UC, &w);
1125		1275
1126	=item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher)	1276	=item C<ev_TYPE_stop> (loop, ev_TYPE *watcher)
1127		1277
1128	Stops the given watcher if active, and clears the pending status (whether	1278	Stops the given watcher if active, and clears the pending status (whether
1129	the watcher was active or not).	1279	the watcher was active or not).
1130		1280
1131	It is possible that stopped watchers are pending - for example,	1281	It is possible that stopped watchers are pending - for example,
…		…
1156	=item ev_cb_set (ev_TYPE *watcher, callback)	1306	=item ev_cb_set (ev_TYPE *watcher, callback)
1157		1307
1158	Change the callback. You can change the callback at virtually any time	1308	Change the callback. You can change the callback at virtually any time
1159	(modulo threads).	1309	(modulo threads).
1160		1310
1161	=item ev_set_priority (ev_TYPE *watcher, priority)	1311	=item ev_set_priority (ev_TYPE *watcher, int priority)
1162		1312
1163	=item int ev_priority (ev_TYPE *watcher)	1313	=item int ev_priority (ev_TYPE *watcher)
1164		1314
1165	Set and query the priority of the watcher. The priority is a small	1315	Set and query the priority of the watcher. The priority is a small
1166	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>	1316	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>
…		…
1197	returns its C<revents> bitset (as if its callback was invoked). If the	1347	returns its C<revents> bitset (as if its callback was invoked). If the
1198	watcher isn't pending it does nothing and returns C<0>.	1348	watcher isn't pending it does nothing and returns C<0>.
1199		1349
1200	Sometimes it can be useful to "poll" a watcher instead of waiting for its	1350	Sometimes it can be useful to "poll" a watcher instead of waiting for its
1201	callback to be invoked, which can be accomplished with this function.	1351	callback to be invoked, which can be accomplished with this function.
		1352
		1353	=item ev_feed_event (loop, ev_TYPE *watcher, int revents)
		1354
		1355	Feeds the given event set into the event loop, as if the specified event
		1356	had happened for the specified watcher (which must be a pointer to an
		1357	initialised but not necessarily started event watcher). Obviously you must
		1358	not free the watcher as long as it has pending events.
		1359
		1360	Stopping the watcher, letting libev invoke it, or calling
		1361	C<ev_clear_pending> will clear the pending event, even if the watcher was
		1362	not started in the first place.
		1363
		1364	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related
		1365	functions that do not need a watcher.
1202		1366
1203	=back	1367	=back
1204		1368
1205		1369
1206	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	1370	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
1317		1481
1318	For example, to emulate how many other event libraries handle priorities,	1482	For example, to emulate how many other event libraries handle priorities,
1319	you can associate an C<ev_idle> watcher to each such watcher, and in	1483	you can associate an C<ev_idle> watcher to each such watcher, and in
1320	the normal watcher callback, you just start the idle watcher. The real	1484	the normal watcher callback, you just start the idle watcher. The real
1321	processing is done in the idle watcher callback. This causes libev to	1485	processing is done in the idle watcher callback. This causes libev to
1322	continously poll and process kernel event data for the watcher, but when	1486	continuously poll and process kernel event data for the watcher, but when
1323	the lock-out case is known to be rare (which in turn is rare :), this is	1487	the lock-out case is known to be rare (which in turn is rare :), this is
1324	workable.	1488	workable.
1325		1489
1326	Usually, however, the lock-out model implemented that way will perform	1490	Usually, however, the lock-out model implemented that way will perform
1327	miserably under the type of load it was designed to handle. In that case,	1491	miserably under the type of load it was designed to handle. In that case,
…		…
1341	{	1505	{
1342	// stop the I/O watcher, we received the event, but	1506	// stop the I/O watcher, we received the event, but
1343	// are not yet ready to handle it.	1507	// are not yet ready to handle it.
1344	ev_io_stop (EV_A_ w);	1508	ev_io_stop (EV_A_ w);
1345		1509
1346	// start the idle watcher to ahndle the actual event.	1510	// start the idle watcher to handle the actual event.
1347	// it will not be executed as long as other watchers	1511	// it will not be executed as long as other watchers
1348	// with the default priority are receiving events.	1512	// with the default priority are receiving events.
1349	ev_idle_start (EV_A_ &idle);	1513	ev_idle_start (EV_A_ &idle);
1350	}	1514	}
1351		1515
…		…
1405		1569
1406	If you cannot use non-blocking mode, then force the use of a	1570	If you cannot use non-blocking mode, then force the use of a
1407	known-to-be-good backend (at the time of this writing, this includes only	1571	known-to-be-good backend (at the time of this writing, this includes only
1408	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file	1572	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file
1409	descriptors for which non-blocking operation makes no sense (such as	1573	descriptors for which non-blocking operation makes no sense (such as
1410	files) - libev doesn't guarentee any specific behaviour in that case.	1574	files) - libev doesn't guarantee any specific behaviour in that case.
1411		1575
1412	Another thing you have to watch out for is that it is quite easy to	1576	Another thing you have to watch out for is that it is quite easy to
1413	receive "spurious" readiness notifications, that is your callback might	1577	receive "spurious" readiness notifications, that is your callback might
1414	be called with C<EV_READ> but a subsequent C<read>(2) will actually block	1578	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
1415	because there is no data. Not only are some backends known to create a	1579	because there is no data. Not only are some backends known to create a
…		…
1480		1644
1481	So when you encounter spurious, unexplained daemon exits, make sure you	1645	So when you encounter spurious, unexplained daemon exits, make sure you
1482	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon	1646	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon
1483	somewhere, as that would have given you a big clue).	1647	somewhere, as that would have given you a big clue).
1484		1648
		1649	=head3 The special problem of accept()ing when you can't
		1650
		1651	Many implementations of the POSIX C<accept> function (for example,
		1652	found in post-2004 Linux) have the peculiar behaviour of not removing a
		1653	connection from the pending queue in all error cases.
		1654
		1655	For example, larger servers often run out of file descriptors (because
		1656	of resource limits), causing C<accept> to fail with C<ENFILE> but not
		1657	rejecting the connection, leading to libev signalling readiness on
		1658	the next iteration again (the connection still exists after all), and
		1659	typically causing the program to loop at 100% CPU usage.
		1660
		1661	Unfortunately, the set of errors that cause this issue differs between
		1662	operating systems, there is usually little the app can do to remedy the
		1663	situation, and no known thread-safe method of removing the connection to
		1664	cope with overload is known (to me).
		1665
		1666	One of the easiest ways to handle this situation is to just ignore it
		1667	- when the program encounters an overload, it will just loop until the
		1668	situation is over. While this is a form of busy waiting, no OS offers an
		1669	event-based way to handle this situation, so it's the best one can do.
		1670
		1671	A better way to handle the situation is to log any errors other than
		1672	C<EAGAIN> and C<EWOULDBLOCK>, making sure not to flood the log with such
		1673	messages, and continue as usual, which at least gives the user an idea of
		1674	what could be wrong ("raise the ulimit!"). For extra points one could stop
		1675	the C<ev_io> watcher on the listening fd "for a while", which reduces CPU
		1676	usage.
		1677
		1678	If your program is single-threaded, then you could also keep a dummy file
		1679	descriptor for overload situations (e.g. by opening F</dev/null>), and
		1680	when you run into C<ENFILE> or C<EMFILE>, close it, run C<accept>,
		1681	close that fd, and create a new dummy fd. This will gracefully refuse
		1682	clients under typical overload conditions.
		1683
		1684	The last way to handle it is to simply log the error and C<exit>, as
		1685	is often done with C<malloc> failures, but this results in an easy
		1686	opportunity for a DoS attack.
1485		1687
1486	=head3 Watcher-Specific Functions	1688	=head3 Watcher-Specific Functions
1487		1689
1488	=over 4	1690	=over 4
1489		1691
…		…
1521	...	1723	...
1522	struct ev_loop *loop = ev_default_init (0);	1724	struct ev_loop *loop = ev_default_init (0);
1523	ev_io stdin_readable;	1725	ev_io stdin_readable;
1524	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1726	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1525	ev_io_start (loop, &stdin_readable);	1727	ev_io_start (loop, &stdin_readable);
1526	ev_loop (loop, 0);	1728	ev_run (loop, 0);
1527		1729
1528		1730
1529	=head2 C<ev_timer> - relative and optionally repeating timeouts	1731	=head2 C<ev_timer> - relative and optionally repeating timeouts
1530		1732
1531	Timer watchers are simple relative timers that generate an event after a	1733	Timer watchers are simple relative timers that generate an event after a
…		…
1540	The callback is guaranteed to be invoked only I<after> its timeout has	1742	The callback is guaranteed to be invoked only I<after> its timeout has
1541	passed (not I<at>, so on systems with very low-resolution clocks this	1743	passed (not I<at>, so on systems with very low-resolution clocks this
1542	might introduce a small delay). If multiple timers become ready during the	1744	might introduce a small delay). If multiple timers become ready during the
1543	same loop iteration then the ones with earlier time-out values are invoked	1745	same loop iteration then the ones with earlier time-out values are invoked
1544	before ones of the same priority with later time-out values (but this is	1746	before ones of the same priority with later time-out values (but this is
1545	no longer true when a callback calls C<ev_loop> recursively).	1747	no longer true when a callback calls C<ev_run> recursively).
1546		1748
1547	=head3 Be smart about timeouts	1749	=head3 Be smart about timeouts
1548		1750
1549	Many real-world problems involve some kind of timeout, usually for error	1751	Many real-world problems involve some kind of timeout, usually for error
1550	recovery. A typical example is an HTTP request - if the other side hangs,	1752	recovery. A typical example is an HTTP request - if the other side hangs,
…		…
1636	ev_tstamp timeout = last_activity + 60.;	1838	ev_tstamp timeout = last_activity + 60.;
1637		1839
1638	// if last_activity + 60. is older than now, we did time out	1840	// if last_activity + 60. is older than now, we did time out
1639	if (timeout < now)	1841	if (timeout < now)
1640	{	1842	{
1641	// timeout occured, take action	1843	// timeout occurred, take action
1642	}	1844	}
1643	else	1845	else
1644	{	1846	{
1645	// callback was invoked, but there was some activity, re-arm	1847	// callback was invoked, but there was some activity, re-arm
1646	// the watcher to fire in last_activity + 60, which is	1848	// the watcher to fire in last_activity + 60, which is
…		…
1668	to the current time (meaning we just have some activity :), then call the	1870	to the current time (meaning we just have some activity :), then call the
1669	callback, which will "do the right thing" and start the timer:	1871	callback, which will "do the right thing" and start the timer:
1670		1872
1671	ev_init (timer, callback);	1873	ev_init (timer, callback);
1672	last_activity = ev_now (loop);	1874	last_activity = ev_now (loop);
1673	callback (loop, timer, EV_TIMEOUT);	1875	callback (loop, timer, EV_TIMER);
1674		1876
1675	And when there is some activity, simply store the current time in	1877	And when there is some activity, simply store the current time in
1676	C<last_activity>, no libev calls at all:	1878	C<last_activity>, no libev calls at all:
1677		1879
1678	last_actiivty = ev_now (loop);	1880	last_activity = ev_now (loop);
1679		1881
1680	This technique is slightly more complex, but in most cases where the	1882	This technique is slightly more complex, but in most cases where the
1681	time-out is unlikely to be triggered, much more efficient.	1883	time-out is unlikely to be triggered, much more efficient.
1682		1884
1683	Changing the timeout is trivial as well (if it isn't hard-coded in the	1885	Changing the timeout is trivial as well (if it isn't hard-coded in the
…		…
1721		1923
1722	=head3 The special problem of time updates	1924	=head3 The special problem of time updates
1723		1925
1724	Establishing the current time is a costly operation (it usually takes at	1926	Establishing the current time is a costly operation (it usually takes at
1725	least two system calls): EV therefore updates its idea of the current	1927	least two system calls): EV therefore updates its idea of the current
1726	time only before and after C<ev_loop> collects new events, which causes a	1928	time only before and after C<ev_run> collects new events, which causes a
1727	growing difference between C<ev_now ()> and C<ev_time ()> when handling	1929	growing difference between C<ev_now ()> and C<ev_time ()> when handling
1728	lots of events in one iteration.	1930	lots of events in one iteration.
1729		1931
1730	The relative timeouts are calculated relative to the C<ev_now ()>	1932	The relative timeouts are calculated relative to the C<ev_now ()>
1731	time. This is usually the right thing as this timestamp refers to the time	1933	time. This is usually the right thing as this timestamp refers to the time
…		…
1737		1939
1738	If the event loop is suspended for a long time, you can also force an	1940	If the event loop is suspended for a long time, you can also force an
1739	update of the time returned by C<ev_now ()> by calling C<ev_now_update	1941	update of the time returned by C<ev_now ()> by calling C<ev_now_update
1740	()>.	1942	()>.
1741		1943
		1944	=head3 The special problems of suspended animation
		1945
		1946	When you leave the server world it is quite customary to hit machines that
		1947	can suspend/hibernate - what happens to the clocks during such a suspend?
		1948
		1949	Some quick tests made with a Linux 2.6.28 indicate that a suspend freezes
		1950	all processes, while the clocks (C<times>, C<CLOCK_MONOTONIC>) continue
		1951	to run until the system is suspended, but they will not advance while the
		1952	system is suspended. That means, on resume, it will be as if the program
		1953	was frozen for a few seconds, but the suspend time will not be counted
		1954	towards C<ev_timer> when a monotonic clock source is used. The real time
		1955	clock advanced as expected, but if it is used as sole clocksource, then a
		1956	long suspend would be detected as a time jump by libev, and timers would
		1957	be adjusted accordingly.
		1958
		1959	I would not be surprised to see different behaviour in different between
		1960	operating systems, OS versions or even different hardware.
		1961
		1962	The other form of suspend (job control, or sending a SIGSTOP) will see a
		1963	time jump in the monotonic clocks and the realtime clock. If the program
		1964	is suspended for a very long time, and monotonic clock sources are in use,
		1965	then you can expect C<ev_timer>s to expire as the full suspension time
		1966	will be counted towards the timers. When no monotonic clock source is in
		1967	use, then libev will again assume a timejump and adjust accordingly.
		1968
		1969	It might be beneficial for this latter case to call C<ev_suspend>
		1970	and C<ev_resume> in code that handles C<SIGTSTP>, to at least get
		1971	deterministic behaviour in this case (you can do nothing against
		1972	C<SIGSTOP>).
		1973
1742	=head3 Watcher-Specific Functions and Data Members	1974	=head3 Watcher-Specific Functions and Data Members
1743		1975
1744	=over 4	1976	=over 4
1745		1977
1746	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	1978	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
…		…
1772	C<repeat> value), or reset the running timer to the C<repeat> value.	2004	C<repeat> value), or reset the running timer to the C<repeat> value.
1773		2005
1774	This sounds a bit complicated, see L<Be smart about timeouts>, above, for a	2006	This sounds a bit complicated, see L<Be smart about timeouts>, above, for a
1775	usage example.	2007	usage example.
1776		2008
		2009	=item ev_tstamp ev_timer_remaining (loop, ev_timer *)
		2010
		2011	Returns the remaining time until a timer fires. If the timer is active,
		2012	then this time is relative to the current event loop time, otherwise it's
		2013	the timeout value currently configured.
		2014
		2015	That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns
		2016	C<5>. When the timer is started and one second passes, C<ev_timer_remaining>
		2017	will return C<4>. When the timer expires and is restarted, it will return
		2018	roughly C<7> (likely slightly less as callback invocation takes some time,
		2019	too), and so on.
		2020
1777	=item ev_tstamp repeat [read-write]	2021	=item ev_tstamp repeat [read-write]
1778		2022
1779	The current C<repeat> value. Will be used each time the watcher times out	2023	The current C<repeat> value. Will be used each time the watcher times out
1780	or C<ev_timer_again> is called, and determines the next timeout (if any),	2024	or C<ev_timer_again> is called, and determines the next timeout (if any),
1781	which is also when any modifications are taken into account.	2025	which is also when any modifications are taken into account.
…		…
1806	}	2050	}
1807		2051
1808	ev_timer mytimer;	2052	ev_timer mytimer;
1809	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	2053	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1810	ev_timer_again (&mytimer); /* start timer */	2054	ev_timer_again (&mytimer); /* start timer */
1811	ev_loop (loop, 0);	2055	ev_run (loop, 0);
1812		2056
1813	// and in some piece of code that gets executed on any "activity":	2057	// and in some piece of code that gets executed on any "activity":
1814	// reset the timeout to start ticking again at 10 seconds	2058	// reset the timeout to start ticking again at 10 seconds
1815	ev_timer_again (&mytimer);	2059	ev_timer_again (&mytimer);
1816		2060
…		…
1842		2086
1843	As with timers, the callback is guaranteed to be invoked only when the	2087	As with timers, the callback is guaranteed to be invoked only when the
1844	point in time where it is supposed to trigger has passed. If multiple	2088	point in time where it is supposed to trigger has passed. If multiple
1845	timers become ready during the same loop iteration then the ones with	2089	timers become ready during the same loop iteration then the ones with
1846	earlier time-out values are invoked before ones with later time-out values	2090	earlier time-out values are invoked before ones with later time-out values
1847	(but this is no longer true when a callback calls C<ev_loop> recursively).	2091	(but this is no longer true when a callback calls C<ev_run> recursively).
1848		2092
1849	=head3 Watcher-Specific Functions and Data Members	2093	=head3 Watcher-Specific Functions and Data Members
1850		2094
1851	=over 4	2095	=over 4
1852		2096
…		…
1980	Example: Call a callback every hour, or, more precisely, whenever the	2224	Example: Call a callback every hour, or, more precisely, whenever the
1981	system time is divisible by 3600. The callback invocation times have	2225	system time is divisible by 3600. The callback invocation times have
1982	potentially a lot of jitter, but good long-term stability.	2226	potentially a lot of jitter, but good long-term stability.
1983		2227
1984	static void	2228	static void
1985	clock_cb (struct ev_loop *loop, ev_io *w, int revents)	2229	clock_cb (struct ev_loop *loop, ev_periodic *w, int revents)
1986	{	2230	{
1987	... its now a full hour (UTC, or TAI or whatever your clock follows)	2231	... its now a full hour (UTC, or TAI or whatever your clock follows)
1988	}	2232	}
1989		2233
1990	ev_periodic hourly_tick;	2234	ev_periodic hourly_tick;
…		…
2016	Signal watchers will trigger an event when the process receives a specific	2260	Signal watchers will trigger an event when the process receives a specific
2017	signal one or more times. Even though signals are very asynchronous, libev	2261	signal one or more times. Even though signals are very asynchronous, libev
2018	will try it's best to deliver signals synchronously, i.e. as part of the	2262	will try it's best to deliver signals synchronously, i.e. as part of the
2019	normal event processing, like any other event.	2263	normal event processing, like any other event.
2020		2264
2021	If you want signals asynchronously, just use C<sigaction> as you would	2265	If you want signals to be delivered truly asynchronously, just use
2022	do without libev and forget about sharing the signal. You can even use	2266	C<sigaction> as you would do without libev and forget about sharing
2023	C<ev_async> from a signal handler to synchronously wake up an event loop.	2267	the signal. You can even use C<ev_async> from a signal handler to
		2268	synchronously wake up an event loop.
2024		2269
2025	You can configure as many watchers as you like per signal. Only when the	2270	You can configure as many watchers as you like for the same signal, but
		2271	only within the same loop, i.e. you can watch for C<SIGINT> in your
		2272	default loop and for C<SIGIO> in another loop, but you cannot watch for
		2273	C<SIGINT> in both the default loop and another loop at the same time. At
		2274	the moment, C<SIGCHLD> is permanently tied to the default loop.
		2275
2026	first watcher gets started will libev actually register a signal handler	2276	When the first watcher gets started will libev actually register something
2027	with the kernel (thus it coexists with your own signal handlers as long as	2277	with the kernel (thus it coexists with your own signal handlers as long as
2028	you don't register any with libev for the same signal). Similarly, when	2278	you don't register any with libev for the same signal).
2029	the last signal watcher for a signal is stopped, libev will reset the
2030	signal handler to SIG_DFL (regardless of what it was set to before).
2031		2279
2032	If possible and supported, libev will install its handlers with	2280	If possible and supported, libev will install its handlers with
2033	C<SA_RESTART> behaviour enabled, so system calls should not be unduly	2281	C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should
2034	interrupted. If you have a problem with system calls getting interrupted by	2282	not be unduly interrupted. If you have a problem with system calls getting
2035	signals you can block all signals in an C<ev_check> watcher and unblock	2283	interrupted by signals you can block all signals in an C<ev_check> watcher
2036	them in an C<ev_prepare> watcher.	2284	and unblock them in an C<ev_prepare> watcher.
		2285
		2286	=head3 The special problem of inheritance over fork/execve/pthread_create
		2287
		2288	Both the signal mask (C<sigprocmask>) and the signal disposition
		2289	(C<sigaction>) are unspecified after starting a signal watcher (and after
		2290	stopping it again), that is, libev might or might not block the signal,
		2291	and might or might not set or restore the installed signal handler.
		2292
		2293	While this does not matter for the signal disposition (libev never
		2294	sets signals to C<SIG_IGN>, so handlers will be reset to C<SIG_DFL> on
		2295	C<execve>), this matters for the signal mask: many programs do not expect
		2296	certain signals to be blocked.
		2297
		2298	This means that before calling C<exec> (from the child) you should reset
		2299	the signal mask to whatever "default" you expect (all clear is a good
		2300	choice usually).
		2301
		2302	The simplest way to ensure that the signal mask is reset in the child is
		2303	to install a fork handler with C<pthread_atfork> that resets it. That will
		2304	catch fork calls done by libraries (such as the libc) as well.
		2305
		2306	In current versions of libev, the signal will not be blocked indefinitely
		2307	unless you use the C<signalfd> API (C<EV_SIGNALFD>). While this reduces
		2308	the window of opportunity for problems, it will not go away, as libev
		2309	I<has> to modify the signal mask, at least temporarily.
		2310
		2311	So I can't stress this enough: I<If you do not reset your signal mask when
		2312	you expect it to be empty, you have a race condition in your code>. This
		2313	is not a libev-specific thing, this is true for most event libraries.
2037		2314
2038	=head3 Watcher-Specific Functions and Data Members	2315	=head3 Watcher-Specific Functions and Data Members
2039		2316
2040	=over 4	2317	=over 4
2041		2318
…		…
2057	Example: Try to exit cleanly on SIGINT.	2334	Example: Try to exit cleanly on SIGINT.
2058		2335
2059	static void	2336	static void
2060	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)	2337	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)
2061	{	2338	{
2062	ev_unloop (loop, EVUNLOOP_ALL);	2339	ev_break (loop, EVBREAK_ALL);
2063	}	2340	}
2064		2341
2065	ev_signal signal_watcher;	2342	ev_signal signal_watcher;
2066	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	2343	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
2067	ev_signal_start (loop, &signal_watcher);	2344	ev_signal_start (loop, &signal_watcher);
…		…
2086	libev)	2363	libev)
2087		2364
2088	=head3 Process Interaction	2365	=head3 Process Interaction
2089		2366
2090	Libev grabs C<SIGCHLD> as soon as the default event loop is	2367	Libev grabs C<SIGCHLD> as soon as the default event loop is
2091	initialised. This is necessary to guarantee proper behaviour even if	2368	initialised. This is necessary to guarantee proper behaviour even if the
2092	the first child watcher is started after the child exits. The occurrence	2369	first child watcher is started after the child exits. The occurrence
2093	of C<SIGCHLD> is recorded asynchronously, but child reaping is done	2370	of C<SIGCHLD> is recorded asynchronously, but child reaping is done
2094	synchronously as part of the event loop processing. Libev always reaps all	2371	synchronously as part of the event loop processing. Libev always reaps all
2095	children, even ones not watched.	2372	children, even ones not watched.
2096		2373
2097	=head3 Overriding the Built-In Processing	2374	=head3 Overriding the Built-In Processing
…		…
2107	=head3 Stopping the Child Watcher	2384	=head3 Stopping the Child Watcher
2108		2385
2109	Currently, the child watcher never gets stopped, even when the	2386	Currently, the child watcher never gets stopped, even when the
2110	child terminates, so normally one needs to stop the watcher in the	2387	child terminates, so normally one needs to stop the watcher in the
2111	callback. Future versions of libev might stop the watcher automatically	2388	callback. Future versions of libev might stop the watcher automatically
2112	when a child exit is detected.	2389	when a child exit is detected (calling C<ev_child_stop> twice is not a
		2390	problem).
2113		2391
2114	=head3 Watcher-Specific Functions and Data Members	2392	=head3 Watcher-Specific Functions and Data Members
2115		2393
2116	=over 4	2394	=over 4
2117		2395
…		…
2452		2730
2453	Prepare and check watchers are usually (but not always) used in pairs:	2731	Prepare and check watchers are usually (but not always) used in pairs:
2454	prepare watchers get invoked before the process blocks and check watchers	2732	prepare watchers get invoked before the process blocks and check watchers
2455	afterwards.	2733	afterwards.
2456		2734
2457	You I<must not> call C<ev_loop> or similar functions that enter	2735	You I<must not> call C<ev_run> or similar functions that enter
2458	the current event loop from either C<ev_prepare> or C<ev_check>	2736	the current event loop from either C<ev_prepare> or C<ev_check>
2459	watchers. Other loops than the current one are fine, however. The	2737	watchers. Other loops than the current one are fine, however. The
2460	rationale behind this is that you do not need to check for recursion in	2738	rationale behind this is that you do not need to check for recursion in
2461	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,	2739	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,
2462	C<ev_check> so if you have one watcher of each kind they will always be	2740	C<ev_check> so if you have one watcher of each kind they will always be
…		…
2630		2908
2631	if (timeout >= 0)	2909	if (timeout >= 0)
2632	// create/start timer	2910	// create/start timer
2633		2911
2634	// poll	2912	// poll
2635	ev_loop (EV_A_ 0);	2913	ev_run (EV_A_ 0);
2636		2914
2637	// stop timer again	2915	// stop timer again
2638	if (timeout >= 0)	2916	if (timeout >= 0)
2639	ev_timer_stop (EV_A_ &to);	2917	ev_timer_stop (EV_A_ &to);
2640		2918
…		…
2718	if you do not want that, you need to temporarily stop the embed watcher).	2996	if you do not want that, you need to temporarily stop the embed watcher).
2719		2997
2720	=item ev_embed_sweep (loop, ev_embed *)	2998	=item ev_embed_sweep (loop, ev_embed *)
2721		2999
2722	Make a single, non-blocking sweep over the embedded loop. This works	3000	Make a single, non-blocking sweep over the embedded loop. This works
2723	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	3001	similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most
2724	appropriate way for embedded loops.	3002	appropriate way for embedded loops.
2725		3003
2726	=item struct ev_loop *other [read-only]	3004	=item struct ev_loop *other [read-only]
2727		3005
2728	The embedded event loop.	3006	The embedded event loop.
…		…
2788	C<ev_default_fork> cheats and calls it in the wrong process, the fork	3066	C<ev_default_fork> cheats and calls it in the wrong process, the fork
2789	handlers will be invoked, too, of course.	3067	handlers will be invoked, too, of course.
2790		3068
2791	=head3 The special problem of life after fork - how is it possible?	3069	=head3 The special problem of life after fork - how is it possible?
2792		3070
2793	Most uses of C<fork()> consist of forking, then some simple calls to ste	3071	Most uses of C<fork()> consist of forking, then some simple calls to set
2794	up/change the process environment, followed by a call to C<exec()>. This	3072	up/change the process environment, followed by a call to C<exec()>. This
2795	sequence should be handled by libev without any problems.	3073	sequence should be handled by libev without any problems.
2796		3074
2797	This changes when the application actually wants to do event handling	3075	This changes when the application actually wants to do event handling
2798	in the child, or both parent in child, in effect "continuing" after the	3076	in the child, or both parent in child, in effect "continuing" after the
…		…
2814	disadvantage of having to use multiple event loops (which do not support	3092	disadvantage of having to use multiple event loops (which do not support
2815	signal watchers).	3093	signal watchers).
2816		3094
2817	When this is not possible, or you want to use the default loop for	3095	When this is not possible, or you want to use the default loop for
2818	other reasons, then in the process that wants to start "fresh", call	3096	other reasons, then in the process that wants to start "fresh", call
2819	C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying	3097	C<ev_loop_destroy (EV_DEFAULT)> followed by C<ev_default_loop (...)>.
2820	the default loop will "orphan" (not stop) all registered watchers, so you	3098	Destroying the default loop will "orphan" (not stop) all registered
2821	have to be careful not to execute code that modifies those watchers. Note	3099	watchers, so you have to be careful not to execute code that modifies
2822	also that in that case, you have to re-register any signal watchers.	3100	those watchers. Note also that in that case, you have to re-register any
		3101	signal watchers.
2823		3102
2824	=head3 Watcher-Specific Functions and Data Members	3103	=head3 Watcher-Specific Functions and Data Members
2825		3104
2826	=over 4	3105	=over 4
2827		3106
2828	=item ev_fork_init (ev_signal *, callback)	3107	=item ev_fork_init (ev_fork *, callback)
2829		3108
2830	Initialises and configures the fork watcher - it has no parameters of any	3109	Initialises and configures the fork watcher - it has no parameters of any
2831	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,	3110	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
2832	believe me.	3111	really.
2833		3112
2834	=back	3113	=back
2835		3114
2836		3115
		3116	=head2 C<ev_cleanup> - even the best things end
		3117
		3118	Cleanup watchers are called just before the event loop is being destroyed
		3119	by a call to C<ev_loop_destroy>.
		3120
		3121	While there is no guarantee that the event loop gets destroyed, cleanup
		3122	watchers provide a convenient method to install cleanup hooks for your
		3123	program, worker threads and so on - you just to make sure to destroy the
		3124	loop when you want them to be invoked.
		3125
		3126	Cleanup watchers are invoked in the same way as any other watcher. Unlike
		3127	all other watchers, they do not keep a reference to the event loop (which
		3128	makes a lot of sense if you think about it). Like all other watchers, you
		3129	can call libev functions in the callback, except C<ev_cleanup_start>.
		3130
		3131	=head3 Watcher-Specific Functions and Data Members
		3132
		3133	=over 4
		3134
		3135	=item ev_cleanup_init (ev_cleanup *, callback)
		3136
		3137	Initialises and configures the cleanup watcher - it has no parameters of
		3138	any kind. There is a C<ev_cleanup_set> macro, but using it is utterly
		3139	pointless, I assure you.
		3140
		3141	=back
		3142
		3143	Example: Register an atexit handler to destroy the default loop, so any
		3144	cleanup functions are called.
		3145
		3146	static void
		3147	program_exits (void)
		3148	{
		3149	ev_loop_destroy (EV_DEFAULT_UC);
		3150	}
		3151
		3152	...
		3153	atexit (program_exits);
		3154
		3155
2837	=head2 C<ev_async> - how to wake up another event loop	3156	=head2 C<ev_async> - how to wake up an event loop
2838		3157
2839	In general, you cannot use an C<ev_loop> from multiple threads or other	3158	In general, you cannot use an C<ev_run> from multiple threads or other
2840	asynchronous sources such as signal handlers (as opposed to multiple event	3159	asynchronous sources such as signal handlers (as opposed to multiple event
2841	loops - those are of course safe to use in different threads).	3160	loops - those are of course safe to use in different threads).
2842		3161
2843	Sometimes, however, you need to wake up another event loop you do not	3162	Sometimes, however, you need to wake up an event loop you do not control,
2844	control, for example because it belongs to another thread. This is what	3163	for example because it belongs to another thread. This is what C<ev_async>
2845	C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you	3164	watchers do: as long as the C<ev_async> watcher is active, you can signal
2846	can signal it by calling C<ev_async_send>, which is thread- and signal	3165	it by calling C<ev_async_send>, which is thread- and signal safe.
2847	safe.
2848		3166
2849	This functionality is very similar to C<ev_signal> watchers, as signals,	3167	This functionality is very similar to C<ev_signal> watchers, as signals,
2850	too, are asynchronous in nature, and signals, too, will be compressed	3168	too, are asynchronous in nature, and signals, too, will be compressed
2851	(i.e. the number of callback invocations may be less than the number of	3169	(i.e. the number of callback invocations may be less than the number of
2852	C<ev_async_sent> calls).	3170	C<ev_async_sent> calls).
…		…
2857	=head3 Queueing	3175	=head3 Queueing
2858		3176
2859	C<ev_async> does not support queueing of data in any way. The reason	3177	C<ev_async> does not support queueing of data in any way. The reason
2860	is that the author does not know of a simple (or any) algorithm for a	3178	is that the author does not know of a simple (or any) algorithm for a
2861	multiple-writer-single-reader queue that works in all cases and doesn't	3179	multiple-writer-single-reader queue that works in all cases and doesn't
2862	need elaborate support such as pthreads.	3180	need elaborate support such as pthreads or unportable memory access
		3181	semantics.
2863		3182
2864	That means that if you want to queue data, you have to provide your own	3183	That means that if you want to queue data, you have to provide your own
2865	queue. But at least I can tell you how to implement locking around your	3184	queue. But at least I can tell you how to implement locking around your
2866	queue:	3185	queue:
2867		3186
…		…
3006		3325
3007	If C<timeout> is less than 0, then no timeout watcher will be	3326	If C<timeout> is less than 0, then no timeout watcher will be
3008	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and	3327	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and
3009	repeat = 0) will be started. C<0> is a valid timeout.	3328	repeat = 0) will be started. C<0> is a valid timeout.
3010		3329
3011	The callback has the type C<void (*cb)(int revents, void *arg)> and gets	3330	The callback has the type C<void (*cb)(int revents, void *arg)> and is
3012	passed an C<revents> set like normal event callbacks (a combination of	3331	passed an C<revents> set like normal event callbacks (a combination of
3013	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>	3332	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMER>) and the C<arg>
3014	value passed to C<ev_once>. Note that it is possible to receive I<both>	3333	value passed to C<ev_once>. Note that it is possible to receive I<both>
3015	a timeout and an io event at the same time - you probably should give io	3334	a timeout and an io event at the same time - you probably should give io
3016	events precedence.	3335	events precedence.
3017		3336
3018	Example: wait up to ten seconds for data to appear on STDIN_FILENO.	3337	Example: wait up to ten seconds for data to appear on STDIN_FILENO.
3019		3338
3020	static void stdin_ready (int revents, void *arg)	3339	static void stdin_ready (int revents, void *arg)
3021	{	3340	{
3022	if (revents & EV_READ)	3341	if (revents & EV_READ)
3023	/* stdin might have data for us, joy! */;	3342	/* stdin might have data for us, joy! */;
3024	else if (revents & EV_TIMEOUT)	3343	else if (revents & EV_TIMER)
3025	/* doh, nothing entered */;	3344	/* doh, nothing entered */;
3026	}	3345	}
3027		3346
3028	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	3347	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
3029		3348
3030	=item ev_feed_event (struct ev_loop *, watcher *, int revents)
3031
3032	Feeds the given event set into the event loop, as if the specified event
3033	had happened for the specified watcher (which must be a pointer to an
3034	initialised but not necessarily started event watcher).
3035
3036	=item ev_feed_fd_event (struct ev_loop *, int fd, int revents)	3349	=item ev_feed_fd_event (loop, int fd, int revents)
3037		3350
3038	Feed an event on the given fd, as if a file descriptor backend detected	3351	Feed an event on the given fd, as if a file descriptor backend detected
3039	the given events it.	3352	the given events it.
3040		3353
3041	=item ev_feed_signal_event (struct ev_loop *loop, int signum)	3354	=item ev_feed_signal_event (loop, int signum)
3042		3355
3043	Feed an event as if the given signal occurred (C<loop> must be the default	3356	Feed an event as if the given signal occurred (C<loop> must be the default
3044	loop!).	3357	loop!).
3045		3358
3046	=back	3359	=back
…		…
3126		3439
3127	=over 4	3440	=over 4
3128		3441
3129	=item ev::TYPE::TYPE ()	3442	=item ev::TYPE::TYPE ()
3130		3443
3131	=item ev::TYPE::TYPE (struct ev_loop *)	3444	=item ev::TYPE::TYPE (loop)
3132		3445
3133	=item ev::TYPE::~TYPE	3446	=item ev::TYPE::~TYPE
3134		3447
3135	The constructor (optionally) takes an event loop to associate the watcher	3448	The constructor (optionally) takes an event loop to associate the watcher
3136	with. If it is omitted, it will use C<EV_DEFAULT>.	3449	with. If it is omitted, it will use C<EV_DEFAULT>.
…		…
3169	myclass obj;	3482	myclass obj;
3170	ev::io iow;	3483	ev::io iow;
3171	iow.set <myclass, &myclass::io_cb> (&obj);	3484	iow.set <myclass, &myclass::io_cb> (&obj);
3172		3485
3173	=item w->set (object *)	3486	=item w->set (object *)
3174
3175	This is an B<experimental> feature that might go away in a future version.
3176		3487
3177	This is a variation of a method callback - leaving out the method to call	3488	This is a variation of a method callback - leaving out the method to call
3178	will default the method to C<operator ()>, which makes it possible to use	3489	will default the method to C<operator ()>, which makes it possible to use
3179	functor objects without having to manually specify the C<operator ()> all	3490	functor objects without having to manually specify the C<operator ()> all
3180	the time. Incidentally, you can then also leave out the template argument	3491	the time. Incidentally, you can then also leave out the template argument
…		…
3213	Example: Use a plain function as callback.	3524	Example: Use a plain function as callback.
3214		3525
3215	static void io_cb (ev::io &w, int revents) { }	3526	static void io_cb (ev::io &w, int revents) { }
3216	iow.set <io_cb> ();	3527	iow.set <io_cb> ();
3217		3528
3218	=item w->set (struct ev_loop *)	3529	=item w->set (loop)
3219		3530
3220	Associates a different C<struct ev_loop> with this watcher. You can only	3531	Associates a different C<struct ev_loop> with this watcher. You can only
3221	do this when the watcher is inactive (and not pending either).	3532	do this when the watcher is inactive (and not pending either).
3222		3533
3223	=item w->set ([arguments])	3534	=item w->set ([arguments])
3224		3535
3225	Basically the same as C<ev_TYPE_set>, with the same arguments. Must be	3536	Basically the same as C<ev_TYPE_set>, with the same arguments. Either this
3226	called at least once. Unlike the C counterpart, an active watcher gets	3537	method or a suitable start method must be called at least once. Unlike the
3227	automatically stopped and restarted when reconfiguring it with this	3538	C counterpart, an active watcher gets automatically stopped and restarted
3228	method.	3539	when reconfiguring it with this method.
3229		3540
3230	=item w->start ()	3541	=item w->start ()
3231		3542
3232	Starts the watcher. Note that there is no C<loop> argument, as the	3543	Starts the watcher. Note that there is no C<loop> argument, as the
3233	constructor already stores the event loop.	3544	constructor already stores the event loop.
3234		3545
		3546	=item w->start ([arguments])
		3547
		3548	Instead of calling C<set> and C<start> methods separately, it is often
		3549	convenient to wrap them in one call. Uses the same type of arguments as
		3550	the configure C<set> method of the watcher.
		3551
3235	=item w->stop ()	3552	=item w->stop ()
3236		3553
3237	Stops the watcher if it is active. Again, no C<loop> argument.	3554	Stops the watcher if it is active. Again, no C<loop> argument.
3238		3555
3239	=item w->again () (C<ev::timer>, C<ev::periodic> only)	3556	=item w->again () (C<ev::timer>, C<ev::periodic> only)
…		…
3251		3568
3252	=back	3569	=back
3253		3570
3254	=back	3571	=back
3255		3572
3256	Example: Define a class with an IO and idle watcher, start one of them in	3573	Example: Define a class with two I/O and idle watchers, start the I/O
3257	the constructor.	3574	watchers in the constructor.
3258		3575
3259	class myclass	3576	class myclass
3260	{	3577	{
3261	ev::io io ; void io_cb (ev::io &w, int revents);	3578	ev::io io ; void io_cb (ev::io &w, int revents);
		3579	ev::io2 io2 ; void io2_cb (ev::io &w, int revents);
3262	ev::idle idle; void idle_cb (ev::idle &w, int revents);	3580	ev::idle idle; void idle_cb (ev::idle &w, int revents);
3263		3581
3264	myclass (int fd)	3582	myclass (int fd)
3265	{	3583	{
3266	io .set <myclass, &myclass::io_cb > (this);	3584	io .set <myclass, &myclass::io_cb > (this);
		3585	io2 .set <myclass, &myclass::io2_cb > (this);
3267	idle.set <myclass, &myclass::idle_cb> (this);	3586	idle.set <myclass, &myclass::idle_cb> (this);
3268		3587
3269	io.start (fd, ev::READ);	3588	io.set (fd, ev::WRITE); // configure the watcher
		3589	io.start (); // start it whenever convenient
		3590
		3591	io2.start (fd, ev::READ); // set + start in one call
3270	}	3592	}
3271	};	3593	};
3272		3594
3273		3595
3274	=head1 OTHER LANGUAGE BINDINGS	3596	=head1 OTHER LANGUAGE BINDINGS
…		…
3320	=item Ocaml	3642	=item Ocaml
3321		3643
3322	Erkki Seppala has written Ocaml bindings for libev, to be found at	3644	Erkki Seppala has written Ocaml bindings for libev, to be found at
3323	L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>.	3645	L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>.
3324		3646
		3647	=item Lua
		3648
		3649	Brian Maher has written a partial interface to libev for lua (at the
		3650	time of this writing, only C<ev_io> and C<ev_timer>), to be found at
		3651	L<http://github.com/brimworks/lua-ev>.
		3652
3325	=back	3653	=back
3326		3654
3327		3655
3328	=head1 MACRO MAGIC	3656	=head1 MACRO MAGIC
3329		3657
…		…
3342	loop argument"). The C<EV_A> form is used when this is the sole argument,	3670	loop argument"). The C<EV_A> form is used when this is the sole argument,
3343	C<EV_A_> is used when other arguments are following. Example:	3671	C<EV_A_> is used when other arguments are following. Example:
3344		3672
3345	ev_unref (EV_A);	3673	ev_unref (EV_A);
3346	ev_timer_add (EV_A_ watcher);	3674	ev_timer_add (EV_A_ watcher);
3347	ev_loop (EV_A_ 0);	3675	ev_run (EV_A_ 0);
3348		3676
3349	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	3677	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
3350	which is often provided by the following macro.	3678	which is often provided by the following macro.
3351		3679
3352	=item C<EV_P>, C<EV_P_>	3680	=item C<EV_P>, C<EV_P_>
…		…
3392	}	3720	}
3393		3721
3394	ev_check check;	3722	ev_check check;
3395	ev_check_init (&check, check_cb);	3723	ev_check_init (&check, check_cb);
3396	ev_check_start (EV_DEFAULT_ &check);	3724	ev_check_start (EV_DEFAULT_ &check);
3397	ev_loop (EV_DEFAULT_ 0);	3725	ev_run (EV_DEFAULT_ 0);
3398		3726
3399	=head1 EMBEDDING	3727	=head1 EMBEDDING
3400		3728
3401	Libev can (and often is) directly embedded into host	3729	Libev can (and often is) directly embedded into host
3402	applications. Examples of applications that embed it include the Deliantra	3730	applications. Examples of applications that embed it include the Deliantra
…		…
3482	libev.m4	3810	libev.m4
3483		3811
3484	=head2 PREPROCESSOR SYMBOLS/MACROS	3812	=head2 PREPROCESSOR SYMBOLS/MACROS
3485		3813
3486	Libev can be configured via a variety of preprocessor symbols you have to	3814	Libev can be configured via a variety of preprocessor symbols you have to
3487	define before including any of its files. The default in the absence of	3815	define before including (or compiling) any of its files. The default in
3488	autoconf is documented for every option.	3816	the absence of autoconf is documented for every option.
		3817
		3818	Symbols marked with "(h)" do not change the ABI, and can have different
		3819	values when compiling libev vs. including F<ev.h>, so it is permissible
		3820	to redefine them before including F<ev.h> without breaking compatibility
		3821	to a compiled library. All other symbols change the ABI, which means all
		3822	users of libev and the libev code itself must be compiled with compatible
		3823	settings.
3489		3824
3490	=over 4	3825	=over 4
3491		3826
		3827	=item EV_COMPAT3 (h)
		3828
		3829	Backwards compatibility is a major concern for libev. This is why this
		3830	release of libev comes with wrappers for the functions and symbols that
		3831	have been renamed between libev version 3 and 4.
		3832
		3833	You can disable these wrappers (to test compatibility with future
		3834	versions) by defining C<EV_COMPAT3> to C<0> when compiling your
		3835	sources. This has the additional advantage that you can drop the C<struct>
		3836	from C<struct ev_loop> declarations, as libev will provide an C<ev_loop>
		3837	typedef in that case.
		3838
		3839	In some future version, the default for C<EV_COMPAT3> will become C<0>,
		3840	and in some even more future version the compatibility code will be
		3841	removed completely.
		3842
3492	=item EV_STANDALONE	3843	=item EV_STANDALONE (h)
3493		3844
3494	Must always be C<1> if you do not use autoconf configuration, which	3845	Must always be C<1> if you do not use autoconf configuration, which
3495	keeps libev from including F<config.h>, and it also defines dummy	3846	keeps libev from including F<config.h>, and it also defines dummy
3496	implementations for some libevent functions (such as logging, which is not	3847	implementations for some libevent functions (such as logging, which is not
3497	supported). It will also not define any of the structs usually found in	3848	supported). It will also not define any of the structs usually found in
3498	F<event.h> that are not directly supported by the libev core alone.	3849	F<event.h> that are not directly supported by the libev core alone.
3499		3850
3500	In stanbdalone mode, libev will still try to automatically deduce the	3851	In standalone mode, libev will still try to automatically deduce the
3501	configuration, but has to be more conservative.	3852	configuration, but has to be more conservative.
3502		3853
3503	=item EV_USE_MONOTONIC	3854	=item EV_USE_MONOTONIC
3504		3855
3505	If defined to be C<1>, libev will try to detect the availability of the	3856	If defined to be C<1>, libev will try to detect the availability of the
…		…
3570	be used is the winsock select). This means that it will call	3921	be used is the winsock select). This means that it will call
3571	C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise,	3922	C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise,
3572	it is assumed that all these functions actually work on fds, even	3923	it is assumed that all these functions actually work on fds, even
3573	on win32. Should not be defined on non-win32 platforms.	3924	on win32. Should not be defined on non-win32 platforms.
3574		3925
3575	=item EV_FD_TO_WIN32_HANDLE	3926	=item EV_FD_TO_WIN32_HANDLE(fd)
3576		3927
3577	If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map	3928	If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map
3578	file descriptors to socket handles. When not defining this symbol (the	3929	file descriptors to socket handles. When not defining this symbol (the
3579	default), then libev will call C<_get_osfhandle>, which is usually	3930	default), then libev will call C<_get_osfhandle>, which is usually
3580	correct. In some cases, programs use their own file descriptor management,	3931	correct. In some cases, programs use their own file descriptor management,
3581	in which case they can provide this function to map fds to socket handles.	3932	in which case they can provide this function to map fds to socket handles.
		3933
		3934	=item EV_WIN32_HANDLE_TO_FD(handle)
		3935
		3936	If C<EV_SELECT_IS_WINSOCKET> then libev maps handles to file descriptors
		3937	using the standard C<_open_osfhandle> function. For programs implementing
		3938	their own fd to handle mapping, overwriting this function makes it easier
		3939	to do so. This can be done by defining this macro to an appropriate value.
		3940
		3941	=item EV_WIN32_CLOSE_FD(fd)
		3942
		3943	If programs implement their own fd to handle mapping on win32, then this
		3944	macro can be used to override the C<close> function, useful to unregister
		3945	file descriptors again. Note that the replacement function has to close
		3946	the underlying OS handle.
3582		3947
3583	=item EV_USE_POLL	3948	=item EV_USE_POLL
3584		3949
3585	If defined to be C<1>, libev will compile in support for the C<poll>(2)	3950	If defined to be C<1>, libev will compile in support for the C<poll>(2)
3586	backend. Otherwise it will be enabled on non-win32 platforms. It	3951	backend. Otherwise it will be enabled on non-win32 platforms. It
…		…
3633	as well as for signal and thread safety in C<ev_async> watchers.	3998	as well as for signal and thread safety in C<ev_async> watchers.
3634		3999
3635	In the absence of this define, libev will use C<sig_atomic_t volatile>	4000	In the absence of this define, libev will use C<sig_atomic_t volatile>
3636	(from F<signal.h>), which is usually good enough on most platforms.	4001	(from F<signal.h>), which is usually good enough on most platforms.
3637		4002
3638	=item EV_H	4003	=item EV_H (h)
3639		4004
3640	The name of the F<ev.h> header file used to include it. The default if	4005	The name of the F<ev.h> header file used to include it. The default if
3641	undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be	4006	undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be
3642	used to virtually rename the F<ev.h> header file in case of conflicts.	4007	used to virtually rename the F<ev.h> header file in case of conflicts.
3643		4008
3644	=item EV_CONFIG_H	4009	=item EV_CONFIG_H (h)
3645		4010
3646	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override	4011	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override
3647	F<ev.c>'s idea of where to find the F<config.h> file, similarly to	4012	F<ev.c>'s idea of where to find the F<config.h> file, similarly to
3648	C<EV_H>, above.	4013	C<EV_H>, above.
3649		4014
3650	=item EV_EVENT_H	4015	=item EV_EVENT_H (h)
3651		4016
3652	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea	4017	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea
3653	of how the F<event.h> header can be found, the default is C<"event.h">.	4018	of how the F<event.h> header can be found, the default is C<"event.h">.
3654		4019
3655	=item EV_PROTOTYPES	4020	=item EV_PROTOTYPES (h)
3656		4021
3657	If defined to be C<0>, then F<ev.h> will not define any function	4022	If defined to be C<0>, then F<ev.h> will not define any function
3658	prototypes, but still define all the structs and other symbols. This is	4023	prototypes, but still define all the structs and other symbols. This is
3659	occasionally useful if you want to provide your own wrapper functions	4024	occasionally useful if you want to provide your own wrapper functions
3660	around libev functions.	4025	around libev functions.
…		…
3682	fine.	4047	fine.
3683		4048
3684	If your embedding application does not need any priorities, defining these	4049	If your embedding application does not need any priorities, defining these
3685	both to C<0> will save some memory and CPU.	4050	both to C<0> will save some memory and CPU.
3686		4051
3687	=item EV_PERIODIC_ENABLE	4052	=item EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE,
		4053	EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE,
		4054	EV_ASYNC_ENABLE, EV_CHILD_ENABLE.
3688		4055
3689	If undefined or defined to be C<1>, then periodic timers are supported. If	4056	If undefined or defined to be C<1> (and the platform supports it), then
3690	defined to be C<0>, then they are not. Disabling them saves a few kB of	4057	the respective watcher type is supported. If defined to be C<0>, then it
3691	code.	4058	is not. Disabling watcher types mainly saves code size.
3692		4059
3693	=item EV_IDLE_ENABLE	4060	=item EV_FEATURES
3694
3695	If undefined or defined to be C<1>, then idle watchers are supported. If
3696	defined to be C<0>, then they are not. Disabling them saves a few kB of
3697	code.
3698
3699	=item EV_EMBED_ENABLE
3700
3701	If undefined or defined to be C<1>, then embed watchers are supported. If
3702	defined to be C<0>, then they are not. Embed watchers rely on most other
3703	watcher types, which therefore must not be disabled.
3704
3705	=item EV_STAT_ENABLE
3706
3707	If undefined or defined to be C<1>, then stat watchers are supported. If
3708	defined to be C<0>, then they are not.
3709
3710	=item EV_FORK_ENABLE
3711
3712	If undefined or defined to be C<1>, then fork watchers are supported. If
3713	defined to be C<0>, then they are not.
3714
3715	=item EV_ASYNC_ENABLE
3716
3717	If undefined or defined to be C<1>, then async watchers are supported. If
3718	defined to be C<0>, then they are not.
3719
3720	=item EV_MINIMAL
3721		4061
3722	If you need to shave off some kilobytes of code at the expense of some	4062	If you need to shave off some kilobytes of code at the expense of some
3723	speed (but with the full API), define this symbol to C<1>. Currently this	4063	speed (but with the full API), you can define this symbol to request
3724	is used to override some inlining decisions, saves roughly 30% code size	4064	certain subsets of functionality. The default is to enable all features
3725	on amd64. It also selects a much smaller 2-heap for timer management over	4065	that can be enabled on the platform.
3726	the default 4-heap.
3727		4066
3728	You can save even more by disabling watcher types you do not need	4067	A typical way to use this symbol is to define it to C<0> (or to a bitset
3729	and setting C<EV_MAXPRI> == C<EV_MINPRI>. Also, disabling C<assert>	4068	with some broad features you want) and then selectively re-enable
3730	(C<-DNDEBUG>) will usually reduce code size a lot.	4069	additional parts you want, for example if you want everything minimal,
		4070	but multiple event loop support, async and child watchers and the poll
		4071	backend, use this:
3731		4072
3732	Defining C<EV_MINIMAL> to C<2> will additionally reduce the core API to	4073	#define EV_FEATURES 0
3733	provide a bare-bones event library. See C<ev.h> for details on what parts	4074	#define EV_MULTIPLICITY 1
3734	of the API are still available, and do not complain if this subset changes	4075	#define EV_USE_POLL 1
3735	over time.	4076	#define EV_CHILD_ENABLE 1
		4077	#define EV_ASYNC_ENABLE 1
		4078
		4079	The actual value is a bitset, it can be a combination of the following
		4080	values:
		4081
		4082	=over 4
		4083
		4084	=item C<1> - faster/larger code
		4085
		4086	Use larger code to speed up some operations.
		4087
		4088	Currently this is used to override some inlining decisions (enlarging the
		4089	code size by roughly 30% on amd64).
		4090
		4091	When optimising for size, use of compiler flags such as C<-Os> with
		4092	gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of
		4093	assertions.
		4094
		4095	=item C<2> - faster/larger data structures
		4096
		4097	Replaces the small 2-heap for timer management by a faster 4-heap, larger
		4098	hash table sizes and so on. This will usually further increase code size
		4099	and can additionally have an effect on the size of data structures at
		4100	runtime.
		4101
		4102	=item C<4> - full API configuration
		4103
		4104	This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and
		4105	enables multiplicity (C<EV_MULTIPLICITY>=1).
		4106
		4107	=item C<8> - full API
		4108
		4109	This enables a lot of the "lesser used" API functions. See C<ev.h> for
		4110	details on which parts of the API are still available without this
		4111	feature, and do not complain if this subset changes over time.
		4112
		4113	=item C<16> - enable all optional watcher types
		4114
		4115	Enables all optional watcher types. If you want to selectively enable
		4116	only some watcher types other than I/O and timers (e.g. prepare,
		4117	embed, async, child...) you can enable them manually by defining
		4118	C<EV_watchertype_ENABLE> to C<1> instead.
		4119
		4120	=item C<32> - enable all backends
		4121
		4122	This enables all backends - without this feature, you need to enable at
		4123	least one backend manually (C<EV_USE_SELECT> is a good choice).
		4124
		4125	=item C<64> - enable OS-specific "helper" APIs
		4126
		4127	Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by
		4128	default.
		4129
		4130	=back
		4131
		4132	Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0>
		4133	reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb
		4134	code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O
		4135	watchers, timers and monotonic clock support.
		4136
		4137	With an intelligent-enough linker (gcc+binutils are intelligent enough
		4138	when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by
		4139	your program might be left out as well - a binary starting a timer and an
		4140	I/O watcher then might come out at only 5Kb.
		4141
		4142	=item EV_AVOID_STDIO
		4143
		4144	If this is set to C<1> at compiletime, then libev will avoid using stdio
		4145	functions (printf, scanf, perror etc.). This will increase the code size
		4146	somewhat, but if your program doesn't otherwise depend on stdio and your
		4147	libc allows it, this avoids linking in the stdio library which is quite
		4148	big.
		4149
		4150	Note that error messages might become less precise when this option is
		4151	enabled.
		4152
		4153	=item EV_NSIG
		4154
		4155	The highest supported signal number, +1 (or, the number of
		4156	signals): Normally, libev tries to deduce the maximum number of signals
		4157	automatically, but sometimes this fails, in which case it can be
		4158	specified. Also, using a lower number than detected (C<32> should be
		4159	good for about any system in existence) can save some memory, as libev
		4160	statically allocates some 12-24 bytes per signal number.
3736		4161
3737	=item EV_PID_HASHSIZE	4162	=item EV_PID_HASHSIZE
3738		4163
3739	C<ev_child> watchers use a small hash table to distribute workload by	4164	C<ev_child> watchers use a small hash table to distribute workload by
3740	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more	4165	pid. The default size is C<16> (or C<1> with C<EV_FEATURES> disabled),
3741	than enough. If you need to manage thousands of children you might want to	4166	usually more than enough. If you need to manage thousands of children you
3742	increase this value (I<must> be a power of two).	4167	might want to increase this value (I<must> be a power of two).
3743		4168
3744	=item EV_INOTIFY_HASHSIZE	4169	=item EV_INOTIFY_HASHSIZE
3745		4170
3746	C<ev_stat> watchers use a small hash table to distribute workload by	4171	C<ev_stat> watchers use a small hash table to distribute workload by
3747	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),	4172	inotify watch id. The default size is C<16> (or C<1> with C<EV_FEATURES>
3748	usually more than enough. If you need to manage thousands of C<ev_stat>	4173	disabled), usually more than enough. If you need to manage thousands of
3749	watchers you might want to increase this value (I<must> be a power of	4174	C<ev_stat> watchers you might want to increase this value (I<must> be a
3750	two).	4175	power of two).
3751		4176
3752	=item EV_USE_4HEAP	4177	=item EV_USE_4HEAP
3753		4178
3754	Heaps are not very cache-efficient. To improve the cache-efficiency of the	4179	Heaps are not very cache-efficient. To improve the cache-efficiency of the
3755	timer and periodics heaps, libev uses a 4-heap when this symbol is defined	4180	timer and periodics heaps, libev uses a 4-heap when this symbol is defined
3756	to C<1>. The 4-heap uses more complicated (longer) code but has noticeably	4181	to C<1>. The 4-heap uses more complicated (longer) code but has noticeably
3757	faster performance with many (thousands) of watchers.	4182	faster performance with many (thousands) of watchers.
3758		4183
3759	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>	4184	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3760	(disabled).	4185	will be C<0>.
3761		4186
3762	=item EV_HEAP_CACHE_AT	4187	=item EV_HEAP_CACHE_AT
3763		4188
3764	Heaps are not very cache-efficient. To improve the cache-efficiency of the	4189	Heaps are not very cache-efficient. To improve the cache-efficiency of the
3765	timer and periodics heaps, libev can cache the timestamp (I<at>) within	4190	timer and periodics heaps, libev can cache the timestamp (I<at>) within
3766	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),	4191	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),
3767	which uses 8-12 bytes more per watcher and a few hundred bytes more code,	4192	which uses 8-12 bytes more per watcher and a few hundred bytes more code,
3768	but avoids random read accesses on heap changes. This improves performance	4193	but avoids random read accesses on heap changes. This improves performance
3769	noticeably with many (hundreds) of watchers.	4194	noticeably with many (hundreds) of watchers.
3770		4195
3771	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>	4196	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3772	(disabled).	4197	will be C<0>.
3773		4198
3774	=item EV_VERIFY	4199	=item EV_VERIFY
3775		4200
3776	Controls how much internal verification (see C<ev_loop_verify ()>) will	4201	Controls how much internal verification (see C<ev_verify ()>) will
3777	be done: If set to C<0>, no internal verification code will be compiled	4202	be done: If set to C<0>, no internal verification code will be compiled
3778	in. If set to C<1>, then verification code will be compiled in, but not	4203	in. If set to C<1>, then verification code will be compiled in, but not
3779	called. If set to C<2>, then the internal verification code will be	4204	called. If set to C<2>, then the internal verification code will be
3780	called once per loop, which can slow down libev. If set to C<3>, then the	4205	called once per loop, which can slow down libev. If set to C<3>, then the
3781	verification code will be called very frequently, which will slow down	4206	verification code will be called very frequently, which will slow down
3782	libev considerably.	4207	libev considerably.
3783		4208
3784	The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be	4209	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3785	C<0>.	4210	will be C<0>.
3786		4211
3787	=item EV_COMMON	4212	=item EV_COMMON
3788		4213
3789	By default, all watchers have a C<void *data> member. By redefining	4214	By default, all watchers have a C<void *data> member. By redefining
3790	this macro to a something else you can include more and other types of	4215	this macro to something else you can include more and other types of
3791	members. You have to define it each time you include one of the files,	4216	members. You have to define it each time you include one of the files,
3792	though, and it must be identical each time.	4217	though, and it must be identical each time.
3793		4218
3794	For example, the perl EV module uses something like this:	4219	For example, the perl EV module uses something like this:
3795		4220
…		…
3848	file.	4273	file.
3849		4274
3850	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	4275	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
3851	that everybody includes and which overrides some configure choices:	4276	that everybody includes and which overrides some configure choices:
3852		4277
3853	#define EV_MINIMAL 1	4278	#define EV_FEATURES 8
3854	#define EV_USE_POLL 0	4279	#define EV_USE_SELECT 1
3855	#define EV_MULTIPLICITY 0
3856	#define EV_PERIODIC_ENABLE 0	4280	#define EV_PREPARE_ENABLE 1
		4281	#define EV_IDLE_ENABLE 1
3857	#define EV_STAT_ENABLE 0	4282	#define EV_SIGNAL_ENABLE 1
3858	#define EV_FORK_ENABLE 0	4283	#define EV_CHILD_ENABLE 1
		4284	#define EV_USE_STDEXCEPT 0
3859	#define EV_CONFIG_H <config.h>	4285	#define EV_CONFIG_H <config.h>
3860	#define EV_MINPRI 0
3861	#define EV_MAXPRI 0
3862		4286
3863	#include "ev++.h"	4287	#include "ev++.h"
3864		4288
3865	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	4289	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
3866		4290
…		…
3928		4352
3929	=back	4353	=back
3930		4354
3931	=head4 THREAD LOCKING EXAMPLE	4355	=head4 THREAD LOCKING EXAMPLE
3932		4356
		4357	Here is a fictitious example of how to run an event loop in a different
		4358	thread than where callbacks are being invoked and watchers are
		4359	created/added/removed.
		4360
		4361	For a real-world example, see the C<EV::Loop::Async> perl module,
		4362	which uses exactly this technique (which is suited for many high-level
		4363	languages).
		4364
		4365	The example uses a pthread mutex to protect the loop data, a condition
		4366	variable to wait for callback invocations, an async watcher to notify the
		4367	event loop thread and an unspecified mechanism to wake up the main thread.
		4368
		4369	First, you need to associate some data with the event loop:
		4370
		4371	typedef struct {
		4372	mutex_t lock; /* global loop lock */
		4373	ev_async async_w;
		4374	thread_t tid;
		4375	cond_t invoke_cv;
		4376	} userdata;
		4377
		4378	void prepare_loop (EV_P)
		4379	{
		4380	// for simplicity, we use a static userdata struct.
		4381	static userdata u;
		4382
		4383	ev_async_init (&u->async_w, async_cb);
		4384	ev_async_start (EV_A_ &u->async_w);
		4385
		4386	pthread_mutex_init (&u->lock, 0);
		4387	pthread_cond_init (&u->invoke_cv, 0);
		4388
		4389	// now associate this with the loop
		4390	ev_set_userdata (EV_A_ u);
		4391	ev_set_invoke_pending_cb (EV_A_ l_invoke);
		4392	ev_set_loop_release_cb (EV_A_ l_release, l_acquire);
		4393
		4394	// then create the thread running ev_loop
		4395	pthread_create (&u->tid, 0, l_run, EV_A);
		4396	}
		4397
		4398	The callback for the C<ev_async> watcher does nothing: the watcher is used
		4399	solely to wake up the event loop so it takes notice of any new watchers
		4400	that might have been added:
		4401
		4402	static void
		4403	async_cb (EV_P_ ev_async *w, int revents)
		4404	{
		4405	// just used for the side effects
		4406	}
		4407
		4408	The C<l_release> and C<l_acquire> callbacks simply unlock/lock the mutex
		4409	protecting the loop data, respectively.
		4410
		4411	static void
		4412	l_release (EV_P)
		4413	{
		4414	userdata *u = ev_userdata (EV_A);
		4415	pthread_mutex_unlock (&u->lock);
		4416	}
		4417
		4418	static void
		4419	l_acquire (EV_P)
		4420	{
		4421	userdata *u = ev_userdata (EV_A);
		4422	pthread_mutex_lock (&u->lock);
		4423	}
		4424
		4425	The event loop thread first acquires the mutex, and then jumps straight
		4426	into C<ev_run>:
		4427
		4428	void *
		4429	l_run (void *thr_arg)
		4430	{
		4431	struct ev_loop *loop = (struct ev_loop *)thr_arg;
		4432
		4433	l_acquire (EV_A);
		4434	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
		4435	ev_run (EV_A_ 0);
		4436	l_release (EV_A);
		4437
		4438	return 0;
		4439	}
		4440
		4441	Instead of invoking all pending watchers, the C<l_invoke> callback will
		4442	signal the main thread via some unspecified mechanism (signals? pipe
		4443	writes? C<Async::Interrupt>?) and then waits until all pending watchers
		4444	have been called (in a while loop because a) spurious wakeups are possible
		4445	and b) skipping inter-thread-communication when there are no pending
		4446	watchers is very beneficial):
		4447
		4448	static void
		4449	l_invoke (EV_P)
		4450	{
		4451	userdata *u = ev_userdata (EV_A);
		4452
		4453	while (ev_pending_count (EV_A))
		4454	{
		4455	wake_up_other_thread_in_some_magic_or_not_so_magic_way ();
		4456	pthread_cond_wait (&u->invoke_cv, &u->lock);
		4457	}
		4458	}
		4459
		4460	Now, whenever the main thread gets told to invoke pending watchers, it
		4461	will grab the lock, call C<ev_invoke_pending> and then signal the loop
		4462	thread to continue:
		4463
		4464	static void
		4465	real_invoke_pending (EV_P)
		4466	{
		4467	userdata *u = ev_userdata (EV_A);
		4468
		4469	pthread_mutex_lock (&u->lock);
		4470	ev_invoke_pending (EV_A);
		4471	pthread_cond_signal (&u->invoke_cv);
		4472	pthread_mutex_unlock (&u->lock);
		4473	}
		4474
		4475	Whenever you want to start/stop a watcher or do other modifications to an
		4476	event loop, you will now have to lock:
		4477
		4478	ev_timer timeout_watcher;
		4479	userdata *u = ev_userdata (EV_A);
		4480
		4481	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
		4482
		4483	pthread_mutex_lock (&u->lock);
		4484	ev_timer_start (EV_A_ &timeout_watcher);
		4485	ev_async_send (EV_A_ &u->async_w);
		4486	pthread_mutex_unlock (&u->lock);
		4487
		4488	Note that sending the C<ev_async> watcher is required because otherwise
		4489	an event loop currently blocking in the kernel will have no knowledge
		4490	about the newly added timer. By waking up the loop it will pick up any new
		4491	watchers in the next event loop iteration.
		4492
3933	=head3 COROUTINES	4493	=head3 COROUTINES
3934		4494
3935	Libev is very accommodating to coroutines ("cooperative threads"):	4495	Libev is very accommodating to coroutines ("cooperative threads"):
3936	libev fully supports nesting calls to its functions from different	4496	libev fully supports nesting calls to its functions from different
3937	coroutines (e.g. you can call C<ev_loop> on the same loop from two	4497	coroutines (e.g. you can call C<ev_run> on the same loop from two
3938	different coroutines, and switch freely between both coroutines running the	4498	different coroutines, and switch freely between both coroutines running
3939	loop, as long as you don't confuse yourself). The only exception is that	4499	the loop, as long as you don't confuse yourself). The only exception is
3940	you must not do this from C<ev_periodic> reschedule callbacks.	4500	that you must not do this from C<ev_periodic> reschedule callbacks.
3941		4501
3942	Care has been taken to ensure that libev does not keep local state inside	4502	Care has been taken to ensure that libev does not keep local state inside
3943	C<ev_loop>, and other calls do not usually allow for coroutine switches as	4503	C<ev_run>, and other calls do not usually allow for coroutine switches as
3944	they do not call any callbacks.	4504	they do not call any callbacks.
3945		4505
3946	=head2 COMPILER WARNINGS	4506	=head2 COMPILER WARNINGS
3947		4507
3948	Depending on your compiler and compiler settings, you might get no or a	4508	Depending on your compiler and compiler settings, you might get no or a
…		…
3959	maintainable.	4519	maintainable.
3960		4520
3961	And of course, some compiler warnings are just plain stupid, or simply	4521	And of course, some compiler warnings are just plain stupid, or simply
3962	wrong (because they don't actually warn about the condition their message	4522	wrong (because they don't actually warn about the condition their message
3963	seems to warn about). For example, certain older gcc versions had some	4523	seems to warn about). For example, certain older gcc versions had some
3964	warnings that resulted an extreme number of false positives. These have	4524	warnings that resulted in an extreme number of false positives. These have
3965	been fixed, but some people still insist on making code warn-free with	4525	been fixed, but some people still insist on making code warn-free with
3966	such buggy versions.	4526	such buggy versions.
3967		4527
3968	While libev is written to generate as few warnings as possible,	4528	While libev is written to generate as few warnings as possible,
3969	"warn-free" code is not a goal, and it is recommended not to build libev	4529	"warn-free" code is not a goal, and it is recommended not to build libev
…		…
4005	I suggest using suppression lists.	4565	I suggest using suppression lists.
4006		4566
4007		4567
4008	=head1 PORTABILITY NOTES	4568	=head1 PORTABILITY NOTES
4009		4569
		4570	=head2 GNU/LINUX 32 BIT LIMITATIONS
		4571
		4572	GNU/Linux is the only common platform that supports 64 bit file/large file
		4573	interfaces but I<disables> them by default.
		4574
		4575	That means that libev compiled in the default environment doesn't support
		4576	files larger than 2GiB or so, which mainly affects C<ev_stat> watchers.
		4577
		4578	Unfortunately, many programs try to work around this GNU/Linux issue
		4579	by enabling the large file API, which makes them incompatible with the
		4580	standard libev compiled for their system.
		4581
		4582	Likewise, libev cannot enable the large file API itself as this would
		4583	suddenly make it incompatible to the default compile time environment,
		4584	i.e. all programs not using special compile switches.
		4585
		4586	=head2 OS/X AND DARWIN BUGS
		4587
		4588	The whole thing is a bug if you ask me - basically any system interface
		4589	you touch is broken, whether it is locales, poll, kqueue or even the
		4590	OpenGL drivers.
		4591
		4592	=head3 C<kqueue> is buggy
		4593
		4594	The kqueue syscall is broken in all known versions - most versions support
		4595	only sockets, many support pipes.
		4596
		4597	Libev tries to work around this by not using C<kqueue> by default on this
		4598	rotten platform, but of course you can still ask for it when creating a
		4599	loop - embedding a socket-only kqueue loop into a select-based one is
		4600	probably going to work well.
		4601
		4602	=head3 C<poll> is buggy
		4603
		4604	Instead of fixing C<kqueue>, Apple replaced their (working) C<poll>
		4605	implementation by something calling C<kqueue> internally around the 10.5.6
		4606	release, so now C<kqueue> I<and> C<poll> are broken.
		4607
		4608	Libev tries to work around this by not using C<poll> by default on
		4609	this rotten platform, but of course you can still ask for it when creating
		4610	a loop.
		4611
		4612	=head3 C<select> is buggy
		4613
		4614	All that's left is C<select>, and of course Apple found a way to fuck this
		4615	one up as well: On OS/X, C<select> actively limits the number of file
		4616	descriptors you can pass in to 1024 - your program suddenly crashes when
		4617	you use more.
		4618
		4619	There is an undocumented "workaround" for this - defining
		4620	C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should>
		4621	work on OS/X.
		4622
		4623	=head2 SOLARIS PROBLEMS AND WORKAROUNDS
		4624
		4625	=head3 C<errno> reentrancy
		4626
		4627	The default compile environment on Solaris is unfortunately so
		4628	thread-unsafe that you can't even use components/libraries compiled
		4629	without C<-D_REENTRANT> in a threaded program, which, of course, isn't
		4630	defined by default. A valid, if stupid, implementation choice.
		4631
		4632	If you want to use libev in threaded environments you have to make sure
		4633	it's compiled with C<_REENTRANT> defined.
		4634
		4635	=head3 Event port backend
		4636
		4637	The scalable event interface for Solaris is called "event
		4638	ports". Unfortunately, this mechanism is very buggy in all major
		4639	releases. If you run into high CPU usage, your program freezes or you get
		4640	a large number of spurious wakeups, make sure you have all the relevant
		4641	and latest kernel patches applied. No, I don't know which ones, but there
		4642	are multiple ones to apply, and afterwards, event ports actually work
		4643	great.
		4644
		4645	If you can't get it to work, you can try running the program by setting
		4646	the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and
		4647	C<select> backends.
		4648
		4649	=head2 AIX POLL BUG
		4650
		4651	AIX unfortunately has a broken C<poll.h> header. Libev works around
		4652	this by trying to avoid the poll backend altogether (i.e. it's not even
		4653	compiled in), which normally isn't a big problem as C<select> works fine
		4654	with large bitsets on AIX, and AIX is dead anyway.
		4655
4010	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS	4656	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
		4657
		4658	=head3 General issues
4011		4659
4012	Win32 doesn't support any of the standards (e.g. POSIX) that libev	4660	Win32 doesn't support any of the standards (e.g. POSIX) that libev
4013	requires, and its I/O model is fundamentally incompatible with the POSIX	4661	requires, and its I/O model is fundamentally incompatible with the POSIX
4014	model. Libev still offers limited functionality on this platform in	4662	model. Libev still offers limited functionality on this platform in
4015	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	4663	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
4016	descriptors. This only applies when using Win32 natively, not when using	4664	descriptors. This only applies when using Win32 natively, not when using
4017	e.g. cygwin.	4665	e.g. cygwin. Actually, it only applies to the microsofts own compilers,
		4666	as every compielr comes with a slightly differently broken/incompatible
		4667	environment.
4018		4668
4019	Lifting these limitations would basically require the full	4669	Lifting these limitations would basically require the full
4020	re-implementation of the I/O system. If you are into these kinds of	4670	re-implementation of the I/O system. If you are into this kind of thing,
4021	things, then note that glib does exactly that for you in a very portable	4671	then note that glib does exactly that for you in a very portable way (note
4022	way (note also that glib is the slowest event library known to man).	4672	also that glib is the slowest event library known to man).
4023		4673
4024	There is no supported compilation method available on windows except	4674	There is no supported compilation method available on windows except
4025	embedding it into other applications.	4675	embedding it into other applications.
4026		4676
4027	Sensible signal handling is officially unsupported by Microsoft - libev	4677	Sensible signal handling is officially unsupported by Microsoft - libev
…		…
4055	you do I<not> compile the F<ev.c> or any other embedded source files!):	4705	you do I<not> compile the F<ev.c> or any other embedded source files!):
4056		4706
4057	#include "evwrap.h"	4707	#include "evwrap.h"
4058	#include "ev.c"	4708	#include "ev.c"
4059		4709
4060	=over 4
4061
4062	=item The winsocket select function	4710	=head3 The winsocket C<select> function
4063		4711
4064	The winsocket C<select> function doesn't follow POSIX in that it	4712	The winsocket C<select> function doesn't follow POSIX in that it
4065	requires socket I<handles> and not socket I<file descriptors> (it is	4713	requires socket I<handles> and not socket I<file descriptors> (it is
4066	also extremely buggy). This makes select very inefficient, and also	4714	also extremely buggy). This makes select very inefficient, and also
4067	requires a mapping from file descriptors to socket handles (the Microsoft	4715	requires a mapping from file descriptors to socket handles (the Microsoft
…		…
4076	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */	4724	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
4077		4725
4078	Note that winsockets handling of fd sets is O(n), so you can easily get a	4726	Note that winsockets handling of fd sets is O(n), so you can easily get a
4079	complexity in the O(n²) range when using win32.	4727	complexity in the O(n²) range when using win32.
4080		4728
4081	=item Limited number of file descriptors	4729	=head3 Limited number of file descriptors
4082		4730
4083	Windows has numerous arbitrary (and low) limits on things.	4731	Windows has numerous arbitrary (and low) limits on things.
4084		4732
4085	Early versions of winsocket's select only supported waiting for a maximum	4733	Early versions of winsocket's select only supported waiting for a maximum
4086	of C<64> handles (probably owning to the fact that all windows kernels	4734	of C<64> handles (probably owning to the fact that all windows kernels
…		…
4101	runtime libraries. This might get you to about C<512> or C<2048> sockets	4749	runtime libraries. This might get you to about C<512> or C<2048> sockets
4102	(depending on windows version and/or the phase of the moon). To get more,	4750	(depending on windows version and/or the phase of the moon). To get more,
4103	you need to wrap all I/O functions and provide your own fd management, but	4751	you need to wrap all I/O functions and provide your own fd management, but
4104	the cost of calling select (O(n²)) will likely make this unworkable.	4752	the cost of calling select (O(n²)) will likely make this unworkable.
4105		4753
4106	=back
4107
4108	=head2 PORTABILITY REQUIREMENTS	4754	=head2 PORTABILITY REQUIREMENTS
4109		4755
4110	In addition to a working ISO-C implementation and of course the	4756	In addition to a working ISO-C implementation and of course the
4111	backend-specific APIs, libev relies on a few additional extensions:	4757	backend-specific APIs, libev relies on a few additional extensions:
4112		4758
…		…
4118	Libev assumes not only that all watcher pointers have the same internal	4764	Libev assumes not only that all watcher pointers have the same internal
4119	structure (guaranteed by POSIX but not by ISO C for example), but it also	4765	structure (guaranteed by POSIX but not by ISO C for example), but it also
4120	assumes that the same (machine) code can be used to call any watcher	4766	assumes that the same (machine) code can be used to call any watcher
4121	callback: The watcher callbacks have different type signatures, but libev	4767	callback: The watcher callbacks have different type signatures, but libev
4122	calls them using an C<ev_watcher *> internally.	4768	calls them using an C<ev_watcher *> internally.
		4769
		4770	=item pointer accesses must be thread-atomic
		4771
		4772	Accessing a pointer value must be atomic, it must both be readable and
		4773	writable in one piece - this is the case on all current architectures.
4123		4774
4124	=item C<sig_atomic_t volatile> must be thread-atomic as well	4775	=item C<sig_atomic_t volatile> must be thread-atomic as well
4125		4776
4126	The type C<sig_atomic_t volatile> (or whatever is defined as	4777	The type C<sig_atomic_t volatile> (or whatever is defined as
4127	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different	4778	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different
…		…
4150	watchers.	4801	watchers.
4151		4802
4152	=item C<double> must hold a time value in seconds with enough accuracy	4803	=item C<double> must hold a time value in seconds with enough accuracy
4153		4804
4154	The type C<double> is used to represent timestamps. It is required to	4805	The type C<double> is used to represent timestamps. It is required to
4155	have at least 51 bits of mantissa (and 9 bits of exponent), which is good	4806	have at least 51 bits of mantissa (and 9 bits of exponent), which is
4156	enough for at least into the year 4000. This requirement is fulfilled by	4807	good enough for at least into the year 4000 with millisecond accuracy
		4808	(the design goal for libev). This requirement is overfulfilled by
4157	implementations implementing IEEE 754, which is basically all existing	4809	implementations using IEEE 754, which is basically all existing ones. With
4158	ones. With IEEE 754 doubles, you get microsecond accuracy until at least	4810	IEEE 754 doubles, you get microsecond accuracy until at least 2200.
4159	2200.
4160		4811
4161	=back	4812	=back
4162		4813
4163	If you know of other additional requirements drop me a note.	4814	If you know of other additional requirements drop me a note.
4164		4815
…		…
4232	involves iterating over all running async watchers or all signal numbers.	4883	involves iterating over all running async watchers or all signal numbers.
4233		4884
4234	=back	4885	=back
4235		4886
4236		4887
		4888	=head1 PORTING FROM LIBEV 3.X TO 4.X
		4889
		4890	The major version 4 introduced some incompatible changes to the API.
		4891
		4892	At the moment, the C<ev.h> header file provides compatibility definitions
		4893	for all changes, so most programs should still compile. The compatibility
		4894	layer might be removed in later versions of libev, so better update to the
		4895	new API early than late.
		4896
		4897	=over 4
		4898
		4899	=item C<EV_COMPAT3> backwards compatibility mechanism
		4900
		4901	The backward compatibility mechanism can be controlled by
		4902	C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING>
		4903	section.
		4904
		4905	=item C<ev_default_destroy> and C<ev_default_fork> have been removed
		4906
		4907	These calls can be replaced easily by their C<ev_loop_xxx> counterparts:
		4908
		4909	ev_loop_destroy (EV_DEFAULT_UC);
		4910	ev_loop_fork (EV_DEFAULT);
		4911
		4912	=item function/symbol renames
		4913
		4914	A number of functions and symbols have been renamed:
		4915
		4916	ev_loop => ev_run
		4917	EVLOOP_NONBLOCK => EVRUN_NOWAIT
		4918	EVLOOP_ONESHOT => EVRUN_ONCE
		4919
		4920	ev_unloop => ev_break
		4921	EVUNLOOP_CANCEL => EVBREAK_CANCEL
		4922	EVUNLOOP_ONE => EVBREAK_ONE
		4923	EVUNLOOP_ALL => EVBREAK_ALL
		4924
		4925	EV_TIMEOUT => EV_TIMER
		4926
		4927	ev_loop_count => ev_iteration
		4928	ev_loop_depth => ev_depth
		4929	ev_loop_verify => ev_verify
		4930
		4931	Most functions working on C<struct ev_loop> objects don't have an
		4932	C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and
		4933	associated constants have been renamed to not collide with the C<struct
		4934	ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme
		4935	as all other watcher types. Note that C<ev_loop_fork> is still called
		4936	C<ev_loop_fork> because it would otherwise clash with the C<ev_fork>
		4937	typedef.
		4938
		4939	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>
		4940
		4941	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different
		4942	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile
		4943	and work, but the library code will of course be larger.
		4944
		4945	=back
		4946
		4947
4237	=head1 GLOSSARY	4948	=head1 GLOSSARY
4238		4949
4239	=over 4	4950	=over 4
4240		4951
4241	=item active	4952	=item active
4242		4953
4243	A watcher is active as long as it has been started (has been attached to	4954	A watcher is active as long as it has been started and not yet stopped.
4244	an event loop) but not yet stopped (disassociated from the event loop).	4955	See L<WATCHER STATES> for details.
4245		4956
4246	=item application	4957	=item application
4247		4958
4248	In this document, an application is whatever is using libev.	4959	In this document, an application is whatever is using libev.
		4960
		4961	=item backend
		4962
		4963	The part of the code dealing with the operating system interfaces.
4249		4964
4250	=item callback	4965	=item callback
4251		4966
4252	The address of a function that is called when some event has been	4967	The address of a function that is called when some event has been
4253	detected. Callbacks are being passed the event loop, the watcher that	4968	detected. Callbacks are being passed the event loop, the watcher that
4254	received the event, and the actual event bitset.	4969	received the event, and the actual event bitset.
4255		4970
4256	=item callback invocation	4971	=item callback/watcher invocation
4257		4972
4258	The act of calling the callback associated with a watcher.	4973	The act of calling the callback associated with a watcher.
4259		4974
4260	=item event	4975	=item event
4261		4976
4262	A change of state of some external event, such as data now being available	4977	A change of state of some external event, such as data now being available
4263	for reading on a file descriptor, time having passed or simply not having	4978	for reading on a file descriptor, time having passed or simply not having
4264	any other events happening anymore.	4979	any other events happening anymore.
4265		4980
4266	In libev, events are represented as single bits (such as C<EV_READ> or	4981	In libev, events are represented as single bits (such as C<EV_READ> or
4267	C<EV_TIMEOUT>).	4982	C<EV_TIMER>).
4268		4983
4269	=item event library	4984	=item event library
4270		4985
4271	A software package implementing an event model and loop.	4986	A software package implementing an event model and loop.
4272		4987
…		…
4280	The model used to describe how an event loop handles and processes	4995	The model used to describe how an event loop handles and processes
4281	watchers and events.	4996	watchers and events.
4282		4997
4283	=item pending	4998	=item pending
4284		4999
4285	A watcher is pending as soon as the corresponding event has been detected,	5000	A watcher is pending as soon as the corresponding event has been
4286	and stops being pending as soon as the watcher will be invoked or its	5001	detected. See L<WATCHER STATES> for details.
4287	pending status is explicitly cleared by the application.
4288
4289	A watcher can be pending, but not active. Stopping a watcher also clears
4290	its pending status.
4291		5002
4292	=item real time	5003	=item real time
4293		5004
4294	The physical time that is observed. It is apparently strictly monotonic :)	5005	The physical time that is observed. It is apparently strictly monotonic :)
4295		5006
…		…
4302	=item watcher	5013	=item watcher
4303		5014
4304	A data structure that describes interest in certain events. Watchers need	5015	A data structure that describes interest in certain events. Watchers need
4305	to be started (attached to an event loop) before they can receive events.	5016	to be started (attached to an event loop) before they can receive events.
4306		5017
4307	=item watcher invocation
4308
4309	The act of calling the callback associated with a watcher.
4310
4311	=back	5018	=back
4312		5019
4313	=head1 AUTHOR	5020	=head1 AUTHOR
4314		5021
4315	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson.	5022	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael
		5023	Magnusson and Emanuele Giaquinta.
4316		5024

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