ViewVC Help

View File | Revision Log | Show Annotations | Download File

/cvs/libev/ev.pod

Comparing libev/ev.pod (file contents):
Revision 1.253 by root, Tue Jul 14 18:33:48 2009 UTC vs.
Revision 1.336 by root, Mon Oct 25 11:10:10 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 "break 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, too.
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
…		…
1088		1179
1089	ev_io w;	1180	ev_io w;
1090	ev_init (&w, my_cb);	1181	ev_init (&w, my_cb);
1091	ev_io_set (&w, STDIN_FILENO, EV_READ);	1182	ev_io_set (&w, STDIN_FILENO, EV_READ);
1092		1183
1093	=item C<ev_TYPE_set> (ev_TYPE *, [args])	1184	=item C<ev_TYPE_set> (ev_TYPE *watcher, [args])
1094		1185
1095	This macro initialises the type-specific parts of a watcher. You need to	1186	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	1187	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	1188	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	1189	macro on a watcher that is active (it can be pending, however, which is a
…		…
1111		1202
1112	Example: Initialise and set an C<ev_io> watcher in one step.	1203	Example: Initialise and set an C<ev_io> watcher in one step.
1113		1204
1114	ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ);	1205	ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ);
1115		1206
1116	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)	1207	=item C<ev_TYPE_start> (loop, ev_TYPE *watcher)
1117		1208
1118	Starts (activates) the given watcher. Only active watchers will receive	1209	Starts (activates) the given watcher. Only active watchers will receive
1119	events. If the watcher is already active nothing will happen.	1210	events. If the watcher is already active nothing will happen.
1120		1211
1121	Example: Start the C<ev_io> watcher that is being abused as example in this	1212	Example: Start the C<ev_io> watcher that is being abused as example in this
1122	whole section.	1213	whole section.
1123		1214
1124	ev_io_start (EV_DEFAULT_UC, &w);	1215	ev_io_start (EV_DEFAULT_UC, &w);
1125		1216
1126	=item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher)	1217	=item C<ev_TYPE_stop> (loop, ev_TYPE *watcher)
1127		1218
1128	Stops the given watcher if active, and clears the pending status (whether	1219	Stops the given watcher if active, and clears the pending status (whether
1129	the watcher was active or not).	1220	the watcher was active or not).
1130		1221
1131	It is possible that stopped watchers are pending - for example,	1222	It is possible that stopped watchers are pending - for example,
…		…
1156	=item ev_cb_set (ev_TYPE *watcher, callback)	1247	=item ev_cb_set (ev_TYPE *watcher, callback)
1157		1248
1158	Change the callback. You can change the callback at virtually any time	1249	Change the callback. You can change the callback at virtually any time
1159	(modulo threads).	1250	(modulo threads).
1160		1251
1161	=item ev_set_priority (ev_TYPE *watcher, priority)	1252	=item ev_set_priority (ev_TYPE *watcher, int priority)
1162		1253
1163	=item int ev_priority (ev_TYPE *watcher)	1254	=item int ev_priority (ev_TYPE *watcher)
1164		1255
1165	Set and query the priority of the watcher. The priority is a small	1256	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>	1257	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>
…		…
1198	watcher isn't pending it does nothing and returns C<0>.	1289	watcher isn't pending it does nothing and returns C<0>.
1199		1290
1200	Sometimes it can be useful to "poll" a watcher instead of waiting for its	1291	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.	1292	callback to be invoked, which can be accomplished with this function.
1202		1293
		1294	=item ev_feed_event (loop, ev_TYPE *watcher, int revents)
		1295
		1296	Feeds the given event set into the event loop, as if the specified event
		1297	had happened for the specified watcher (which must be a pointer to an
		1298	initialised but not necessarily started event watcher). Obviously you must
		1299	not free the watcher as long as it has pending events.
		1300
		1301	Stopping the watcher, letting libev invoke it, or calling
		1302	C<ev_clear_pending> will clear the pending event, even if the watcher was
		1303	not started in the first place.
		1304
		1305	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related
		1306	functions that do not need a watcher.
		1307
1203	=back	1308	=back
1204
1205		1309
1206	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	1310	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
1207		1311
1208	Each watcher has, by default, a member C<void *data> that you can change	1312	Each watcher has, by default, a member C<void *data> that you can change
1209	and read at any time: libev will completely ignore it. This can be used	1313	and read at any time: libev will completely ignore it. This can be used
…		…
1265	t2_cb (EV_P_ ev_timer *w, int revents)	1369	t2_cb (EV_P_ ev_timer *w, int revents)
1266	{	1370	{
1267	struct my_biggy big = (struct my_biggy *)	1371	struct my_biggy big = (struct my_biggy *)
1268	(((char *)w) - offsetof (struct my_biggy, t2));	1372	(((char *)w) - offsetof (struct my_biggy, t2));
1269	}	1373	}
		1374
		1375	=head2 WATCHER STATES
		1376
		1377	There are various watcher states mentioned throughout this manual -
		1378	active, pending and so on. In this section these states and the rules to
		1379	transition between them will be described in more detail - and while these
		1380	rules might look complicated, they usually do "the right thing".
		1381
		1382	=over 4
		1383
		1384	=item initialiased
		1385
		1386	Before a watcher can be registered with the event looop it has to be
		1387	initialised. This can be done with a call to C<ev_TYPE_init>, or calls to
		1388	C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function.
		1389
		1390	In this state it is simply some block of memory that is suitable for use
		1391	in an event loop. It can be moved around, freed, reused etc. at will.
		1392
		1393	=item started/running/active
		1394
		1395	Once a watcher has been started with a call to C<ev_TYPE_start> it becomes
		1396	property of the event loop, and is actively waiting for events. While in
		1397	this state it cannot be accessed (except in a few documented ways), moved,
		1398	freed or anything else - the only legal thing is to keep a pointer to it,
		1399	and call libev functions on it that are documented to work on active watchers.
		1400
		1401	=item pending
		1402
		1403	If a watcher is active and libev determines that an event it is interested
		1404	in has occurred (such as a timer expiring), it will become pending. It will
		1405	stay in this pending state until either it is stopped or its callback is
		1406	about to be invoked, so it is not normally pending inside the watcher
		1407	callback.
		1408
		1409	The watcher might or might not be active while it is pending (for example,
		1410	an expired non-repeating timer can be pending but no longer active). If it
		1411	is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>),
		1412	but it is still property of the event loop at this time, so cannot be
		1413	moved, freed or reused. And if it is active the rules described in the
		1414	previous item still apply.
		1415
		1416	It is also possible to feed an event on a watcher that is not active (e.g.
		1417	via C<ev_feed_event>), in which case it becomes pending without being
		1418	active.
		1419
		1420	=item stopped
		1421
		1422	A watcher can be stopped implicitly by libev (in which case it might still
		1423	be pending), or explicitly by calling its C<ev_TYPE_stop> function. The
		1424	latter will clear any pending state the watcher might be in, regardless
		1425	of whether it was active or not, so stopping a watcher explicitly before
		1426	freeing it is often a good idea.
		1427
		1428	While stopped (and not pending) the watcher is essentially in the
		1429	initialised state, that is it can be reused, moved, modified in any way
		1430	you wish.
		1431
		1432	=back
1270		1433
1271	=head2 WATCHER PRIORITY MODELS	1434	=head2 WATCHER PRIORITY MODELS
1272		1435
1273	Many event loops support I<watcher priorities>, which are usually small	1436	Many event loops support I<watcher priorities>, which are usually small
1274	integers that influence the ordering of event callback invocation	1437	integers that influence the ordering of event callback invocation
…		…
1317		1480
1318	For example, to emulate how many other event libraries handle priorities,	1481	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	1482	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	1483	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	1484	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	1485	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	1486	the lock-out case is known to be rare (which in turn is rare :), this is
1324	workable.	1487	workable.
1325		1488
1326	Usually, however, the lock-out model implemented that way will perform	1489	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,	1490	miserably under the type of load it was designed to handle. In that case,
…		…
1341	{	1504	{
1342	// stop the I/O watcher, we received the event, but	1505	// stop the I/O watcher, we received the event, but
1343	// are not yet ready to handle it.	1506	// are not yet ready to handle it.
1344	ev_io_stop (EV_A_ w);	1507	ev_io_stop (EV_A_ w);
1345		1508
1346	// start the idle watcher to ahndle the actual event.	1509	// start the idle watcher to handle the actual event.
1347	// it will not be executed as long as other watchers	1510	// it will not be executed as long as other watchers
1348	// with the default priority are receiving events.	1511	// with the default priority are receiving events.
1349	ev_idle_start (EV_A_ &idle);	1512	ev_idle_start (EV_A_ &idle);
1350	}	1513	}
1351		1514
…		…
1405		1568
1406	If you cannot use non-blocking mode, then force the use of a	1569	If you cannot use non-blocking mode, then force the use of a
1407	known-to-be-good backend (at the time of this writing, this includes only	1570	known-to-be-good backend (at the time of this writing, this includes only
1408	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file	1571	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file
1409	descriptors for which non-blocking operation makes no sense (such as	1572	descriptors for which non-blocking operation makes no sense (such as
1410	files) - libev doesn't guarentee any specific behaviour in that case.	1573	files) - libev doesn't guarantee any specific behaviour in that case.
1411		1574
1412	Another thing you have to watch out for is that it is quite easy to	1575	Another thing you have to watch out for is that it is quite easy to
1413	receive "spurious" readiness notifications, that is your callback might	1576	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	1577	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	1578	because there is no data. Not only are some backends known to create a
…		…
1480		1643
1481	So when you encounter spurious, unexplained daemon exits, make sure you	1644	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	1645	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).	1646	somewhere, as that would have given you a big clue).
1484		1647
		1648	=head3 The special problem of accept()ing when you can't
		1649
		1650	Many implementations of the POSIX C<accept> function (for example,
		1651	found in post-2004 Linux) have the peculiar behaviour of not removing a
		1652	connection from the pending queue in all error cases.
		1653
		1654	For example, larger servers often run out of file descriptors (because
		1655	of resource limits), causing C<accept> to fail with C<ENFILE> but not
		1656	rejecting the connection, leading to libev signalling readiness on
		1657	the next iteration again (the connection still exists after all), and
		1658	typically causing the program to loop at 100% CPU usage.
		1659
		1660	Unfortunately, the set of errors that cause this issue differs between
		1661	operating systems, there is usually little the app can do to remedy the
		1662	situation, and no known thread-safe method of removing the connection to
		1663	cope with overload is known (to me).
		1664
		1665	One of the easiest ways to handle this situation is to just ignore it
		1666	- when the program encounters an overload, it will just loop until the
		1667	situation is over. While this is a form of busy waiting, no OS offers an
		1668	event-based way to handle this situation, so it's the best one can do.
		1669
		1670	A better way to handle the situation is to log any errors other than
		1671	C<EAGAIN> and C<EWOULDBLOCK>, making sure not to flood the log with such
		1672	messages, and continue as usual, which at least gives the user an idea of
		1673	what could be wrong ("raise the ulimit!"). For extra points one could stop
		1674	the C<ev_io> watcher on the listening fd "for a while", which reduces CPU
		1675	usage.
		1676
		1677	If your program is single-threaded, then you could also keep a dummy file
		1678	descriptor for overload situations (e.g. by opening F</dev/null>), and
		1679	when you run into C<ENFILE> or C<EMFILE>, close it, run C<accept>,
		1680	close that fd, and create a new dummy fd. This will gracefully refuse
		1681	clients under typical overload conditions.
		1682
		1683	The last way to handle it is to simply log the error and C<exit>, as
		1684	is often done with C<malloc> failures, but this results in an easy
		1685	opportunity for a DoS attack.
1485		1686
1486	=head3 Watcher-Specific Functions	1687	=head3 Watcher-Specific Functions
1487		1688
1488	=over 4	1689	=over 4
1489		1690
…		…
1521	...	1722	...
1522	struct ev_loop *loop = ev_default_init (0);	1723	struct ev_loop *loop = ev_default_init (0);
1523	ev_io stdin_readable;	1724	ev_io stdin_readable;
1524	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1725	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1525	ev_io_start (loop, &stdin_readable);	1726	ev_io_start (loop, &stdin_readable);
1526	ev_loop (loop, 0);	1727	ev_run (loop, 0);
1527		1728
1528		1729
1529	=head2 C<ev_timer> - relative and optionally repeating timeouts	1730	=head2 C<ev_timer> - relative and optionally repeating timeouts
1530		1731
1531	Timer watchers are simple relative timers that generate an event after a	1732	Timer watchers are simple relative timers that generate an event after a
…		…
1540	The callback is guaranteed to be invoked only I<after> its timeout has	1741	The callback is guaranteed to be invoked only I<after> its timeout has
1541	passed (not I<at>, so on systems with very low-resolution clocks this	1742	passed (not I<at>, so on systems with very low-resolution clocks this
1542	might introduce a small delay). If multiple timers become ready during the	1743	might introduce a small delay). If multiple timers become ready during the
1543	same loop iteration then the ones with earlier time-out values are invoked	1744	same loop iteration then the ones with earlier time-out values are invoked
1544	before ones of the same priority with later time-out values (but this is	1745	before ones of the same priority with later time-out values (but this is
1545	no longer true when a callback calls C<ev_loop> recursively).	1746	no longer true when a callback calls C<ev_run> recursively).
1546		1747
1547	=head3 Be smart about timeouts	1748	=head3 Be smart about timeouts
1548		1749
1549	Many real-world problems involve some kind of timeout, usually for error	1750	Many real-world problems involve some kind of timeout, usually for error
1550	recovery. A typical example is an HTTP request - if the other side hangs,	1751	recovery. A typical example is an HTTP request - if the other side hangs,
…		…
1636	ev_tstamp timeout = last_activity + 60.;	1837	ev_tstamp timeout = last_activity + 60.;
1637		1838
1638	// if last_activity + 60. is older than now, we did time out	1839	// if last_activity + 60. is older than now, we did time out
1639	if (timeout < now)	1840	if (timeout < now)
1640	{	1841	{
1641	// timeout occured, take action	1842	// timeout occurred, take action
1642	}	1843	}
1643	else	1844	else
1644	{	1845	{
1645	// callback was invoked, but there was some activity, re-arm	1846	// callback was invoked, but there was some activity, re-arm
1646	// the watcher to fire in last_activity + 60, which is	1847	// the watcher to fire in last_activity + 60, which is
…		…
1668	to the current time (meaning we just have some activity :), then call the	1869	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:	1870	callback, which will "do the right thing" and start the timer:
1670		1871
1671	ev_init (timer, callback);	1872	ev_init (timer, callback);
1672	last_activity = ev_now (loop);	1873	last_activity = ev_now (loop);
1673	callback (loop, timer, EV_TIMEOUT);	1874	callback (loop, timer, EV_TIMER);
1674		1875
1675	And when there is some activity, simply store the current time in	1876	And when there is some activity, simply store the current time in
1676	C<last_activity>, no libev calls at all:	1877	C<last_activity>, no libev calls at all:
1677		1878
1678	last_actiivty = ev_now (loop);	1879	last_activity = ev_now (loop);
1679		1880
1680	This technique is slightly more complex, but in most cases where the	1881	This technique is slightly more complex, but in most cases where the
1681	time-out is unlikely to be triggered, much more efficient.	1882	time-out is unlikely to be triggered, much more efficient.
1682		1883
1683	Changing the timeout is trivial as well (if it isn't hard-coded in the	1884	Changing the timeout is trivial as well (if it isn't hard-coded in the
…		…
1721		1922
1722	=head3 The special problem of time updates	1923	=head3 The special problem of time updates
1723		1924
1724	Establishing the current time is a costly operation (it usually takes at	1925	Establishing the current time is a costly operation (it usually takes at
1725	least two system calls): EV therefore updates its idea of the current	1926	least two system calls): EV therefore updates its idea of the current
1726	time only before and after C<ev_loop> collects new events, which causes a	1927	time only before and after C<ev_run> collects new events, which causes a
1727	growing difference between C<ev_now ()> and C<ev_time ()> when handling	1928	growing difference between C<ev_now ()> and C<ev_time ()> when handling
1728	lots of events in one iteration.	1929	lots of events in one iteration.
1729		1930
1730	The relative timeouts are calculated relative to the C<ev_now ()>	1931	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	1932	time. This is usually the right thing as this timestamp refers to the time
…		…
1737		1938
1738	If the event loop is suspended for a long time, you can also force an	1939	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	1940	update of the time returned by C<ev_now ()> by calling C<ev_now_update
1740	()>.	1941	()>.
1741		1942
		1943	=head3 The special problems of suspended animation
		1944
		1945	When you leave the server world it is quite customary to hit machines that
		1946	can suspend/hibernate - what happens to the clocks during such a suspend?
		1947
		1948	Some quick tests made with a Linux 2.6.28 indicate that a suspend freezes
		1949	all processes, while the clocks (C<times>, C<CLOCK_MONOTONIC>) continue
		1950	to run until the system is suspended, but they will not advance while the
		1951	system is suspended. That means, on resume, it will be as if the program
		1952	was frozen for a few seconds, but the suspend time will not be counted
		1953	towards C<ev_timer> when a monotonic clock source is used. The real time
		1954	clock advanced as expected, but if it is used as sole clocksource, then a
		1955	long suspend would be detected as a time jump by libev, and timers would
		1956	be adjusted accordingly.
		1957
		1958	I would not be surprised to see different behaviour in different between
		1959	operating systems, OS versions or even different hardware.
		1960
		1961	The other form of suspend (job control, or sending a SIGSTOP) will see a
		1962	time jump in the monotonic clocks and the realtime clock. If the program
		1963	is suspended for a very long time, and monotonic clock sources are in use,
		1964	then you can expect C<ev_timer>s to expire as the full suspension time
		1965	will be counted towards the timers. When no monotonic clock source is in
		1966	use, then libev will again assume a timejump and adjust accordingly.
		1967
		1968	It might be beneficial for this latter case to call C<ev_suspend>
		1969	and C<ev_resume> in code that handles C<SIGTSTP>, to at least get
		1970	deterministic behaviour in this case (you can do nothing against
		1971	C<SIGSTOP>).
		1972
1742	=head3 Watcher-Specific Functions and Data Members	1973	=head3 Watcher-Specific Functions and Data Members
1743		1974
1744	=over 4	1975	=over 4
1745		1976
1746	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	1977	=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.	2003	C<repeat> value), or reset the running timer to the C<repeat> value.
1773		2004
1774	This sounds a bit complicated, see L<Be smart about timeouts>, above, for a	2005	This sounds a bit complicated, see L<Be smart about timeouts>, above, for a
1775	usage example.	2006	usage example.
1776		2007
		2008	=item ev_tstamp ev_timer_remaining (loop, ev_timer *)
		2009
		2010	Returns the remaining time until a timer fires. If the timer is active,
		2011	then this time is relative to the current event loop time, otherwise it's
		2012	the timeout value currently configured.
		2013
		2014	That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns
		2015	C<5>. When the timer is started and one second passes, C<ev_timer_remaining>
		2016	will return C<4>. When the timer expires and is restarted, it will return
		2017	roughly C<7> (likely slightly less as callback invocation takes some time,
		2018	too), and so on.
		2019
1777	=item ev_tstamp repeat [read-write]	2020	=item ev_tstamp repeat [read-write]
1778		2021
1779	The current C<repeat> value. Will be used each time the watcher times out	2022	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),	2023	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.	2024	which is also when any modifications are taken into account.
…		…
1806	}	2049	}
1807		2050
1808	ev_timer mytimer;	2051	ev_timer mytimer;
1809	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	2052	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1810	ev_timer_again (&mytimer); /* start timer */	2053	ev_timer_again (&mytimer); /* start timer */
1811	ev_loop (loop, 0);	2054	ev_run (loop, 0);
1812		2055
1813	// and in some piece of code that gets executed on any "activity":	2056	// and in some piece of code that gets executed on any "activity":
1814	// reset the timeout to start ticking again at 10 seconds	2057	// reset the timeout to start ticking again at 10 seconds
1815	ev_timer_again (&mytimer);	2058	ev_timer_again (&mytimer);
1816		2059
…		…
1842		2085
1843	As with timers, the callback is guaranteed to be invoked only when the	2086	As with timers, the callback is guaranteed to be invoked only when the
1844	point in time where it is supposed to trigger has passed. If multiple	2087	point in time where it is supposed to trigger has passed. If multiple
1845	timers become ready during the same loop iteration then the ones with	2088	timers become ready during the same loop iteration then the ones with
1846	earlier time-out values are invoked before ones with later time-out values	2089	earlier time-out values are invoked before ones with later time-out values
1847	(but this is no longer true when a callback calls C<ev_loop> recursively).	2090	(but this is no longer true when a callback calls C<ev_run> recursively).
1848		2091
1849	=head3 Watcher-Specific Functions and Data Members	2092	=head3 Watcher-Specific Functions and Data Members
1850		2093
1851	=over 4	2094	=over 4
1852		2095
…		…
1980	Example: Call a callback every hour, or, more precisely, whenever the	2223	Example: Call a callback every hour, or, more precisely, whenever the
1981	system time is divisible by 3600. The callback invocation times have	2224	system time is divisible by 3600. The callback invocation times have
1982	potentially a lot of jitter, but good long-term stability.	2225	potentially a lot of jitter, but good long-term stability.
1983		2226
1984	static void	2227	static void
1985	clock_cb (struct ev_loop *loop, ev_io *w, int revents)	2228	clock_cb (struct ev_loop *loop, ev_periodic *w, int revents)
1986	{	2229	{
1987	... its now a full hour (UTC, or TAI or whatever your clock follows)	2230	... its now a full hour (UTC, or TAI or whatever your clock follows)
1988	}	2231	}
1989		2232
1990	ev_periodic hourly_tick;	2233	ev_periodic hourly_tick;
…		…
2016	Signal watchers will trigger an event when the process receives a specific	2259	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	2260	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	2261	will try it's best to deliver signals synchronously, i.e. as part of the
2019	normal event processing, like any other event.	2262	normal event processing, like any other event.
2020		2263
2021	If you want signals asynchronously, just use C<sigaction> as you would	2264	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	2265	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.	2266	the signal. You can even use C<ev_async> from a signal handler to
		2267	synchronously wake up an event loop.
2024		2268
2025	You can configure as many watchers as you like per signal. Only when the	2269	You can configure as many watchers as you like for the same signal, but
		2270	only within the same loop, i.e. you can watch for C<SIGINT> in your
		2271	default loop and for C<SIGIO> in another loop, but you cannot watch for
		2272	C<SIGINT> in both the default loop and another loop at the same time. At
		2273	the moment, C<SIGCHLD> is permanently tied to the default loop.
		2274
2026	first watcher gets started will libev actually register a signal handler	2275	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	2276	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	2277	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		2278
2032	If possible and supported, libev will install its handlers with	2279	If possible and supported, libev will install its handlers with
2033	C<SA_RESTART> behaviour enabled, so system calls should not be unduly	2280	C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should
2034	interrupted. If you have a problem with system calls getting interrupted by	2281	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	2282	interrupted by signals you can block all signals in an C<ev_check> watcher
2036	them in an C<ev_prepare> watcher.	2283	and unblock them in an C<ev_prepare> watcher.
		2284
		2285	=head3 The special problem of inheritance over fork/execve/pthread_create
		2286
		2287	Both the signal mask (C<sigprocmask>) and the signal disposition
		2288	(C<sigaction>) are unspecified after starting a signal watcher (and after
		2289	stopping it again), that is, libev might or might not block the signal,
		2290	and might or might not set or restore the installed signal handler.
		2291
		2292	While this does not matter for the signal disposition (libev never
		2293	sets signals to C<SIG_IGN>, so handlers will be reset to C<SIG_DFL> on
		2294	C<execve>), this matters for the signal mask: many programs do not expect
		2295	certain signals to be blocked.
		2296
		2297	This means that before calling C<exec> (from the child) you should reset
		2298	the signal mask to whatever "default" you expect (all clear is a good
		2299	choice usually).
		2300
		2301	The simplest way to ensure that the signal mask is reset in the child is
		2302	to install a fork handler with C<pthread_atfork> that resets it. That will
		2303	catch fork calls done by libraries (such as the libc) as well.
		2304
		2305	In current versions of libev, the signal will not be blocked indefinitely
		2306	unless you use the C<signalfd> API (C<EV_SIGNALFD>). While this reduces
		2307	the window of opportunity for problems, it will not go away, as libev
		2308	I<has> to modify the signal mask, at least temporarily.
		2309
		2310	So I can't stress this enough: I<If you do not reset your signal mask when
		2311	you expect it to be empty, you have a race condition in your code>. This
		2312	is not a libev-specific thing, this is true for most event libraries.
2037		2313
2038	=head3 Watcher-Specific Functions and Data Members	2314	=head3 Watcher-Specific Functions and Data Members
2039		2315
2040	=over 4	2316	=over 4
2041		2317
…		…
2057	Example: Try to exit cleanly on SIGINT.	2333	Example: Try to exit cleanly on SIGINT.
2058		2334
2059	static void	2335	static void
2060	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)	2336	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)
2061	{	2337	{
2062	ev_unloop (loop, EVUNLOOP_ALL);	2338	ev_break (loop, EVBREAK_ALL);
2063	}	2339	}
2064		2340
2065	ev_signal signal_watcher;	2341	ev_signal signal_watcher;
2066	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	2342	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
2067	ev_signal_start (loop, &signal_watcher);	2343	ev_signal_start (loop, &signal_watcher);
…		…
2086	libev)	2362	libev)
2087		2363
2088	=head3 Process Interaction	2364	=head3 Process Interaction
2089		2365
2090	Libev grabs C<SIGCHLD> as soon as the default event loop is	2366	Libev grabs C<SIGCHLD> as soon as the default event loop is
2091	initialised. This is necessary to guarantee proper behaviour even if	2367	initialised. This is necessary to guarantee proper behaviour even if the
2092	the first child watcher is started after the child exits. The occurrence	2368	first child watcher is started after the child exits. The occurrence
2093	of C<SIGCHLD> is recorded asynchronously, but child reaping is done	2369	of C<SIGCHLD> is recorded asynchronously, but child reaping is done
2094	synchronously as part of the event loop processing. Libev always reaps all	2370	synchronously as part of the event loop processing. Libev always reaps all
2095	children, even ones not watched.	2371	children, even ones not watched.
2096		2372
2097	=head3 Overriding the Built-In Processing	2373	=head3 Overriding the Built-In Processing
…		…
2107	=head3 Stopping the Child Watcher	2383	=head3 Stopping the Child Watcher
2108		2384
2109	Currently, the child watcher never gets stopped, even when the	2385	Currently, the child watcher never gets stopped, even when the
2110	child terminates, so normally one needs to stop the watcher in the	2386	child terminates, so normally one needs to stop the watcher in the
2111	callback. Future versions of libev might stop the watcher automatically	2387	callback. Future versions of libev might stop the watcher automatically
2112	when a child exit is detected.	2388	when a child exit is detected (calling C<ev_child_stop> twice is not a
		2389	problem).
2113		2390
2114	=head3 Watcher-Specific Functions and Data Members	2391	=head3 Watcher-Specific Functions and Data Members
2115		2392
2116	=over 4	2393	=over 4
2117		2394
…		…
2452		2729
2453	Prepare and check watchers are usually (but not always) used in pairs:	2730	Prepare and check watchers are usually (but not always) used in pairs:
2454	prepare watchers get invoked before the process blocks and check watchers	2731	prepare watchers get invoked before the process blocks and check watchers
2455	afterwards.	2732	afterwards.
2456		2733
2457	You I<must not> call C<ev_loop> or similar functions that enter	2734	You I<must not> call C<ev_run> or similar functions that enter
2458	the current event loop from either C<ev_prepare> or C<ev_check>	2735	the current event loop from either C<ev_prepare> or C<ev_check>
2459	watchers. Other loops than the current one are fine, however. The	2736	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	2737	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,	2738	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	2739	C<ev_check> so if you have one watcher of each kind they will always be
…		…
2630		2907
2631	if (timeout >= 0)	2908	if (timeout >= 0)
2632	// create/start timer	2909	// create/start timer
2633		2910
2634	// poll	2911	// poll
2635	ev_loop (EV_A_ 0);	2912	ev_run (EV_A_ 0);
2636		2913
2637	// stop timer again	2914	// stop timer again
2638	if (timeout >= 0)	2915	if (timeout >= 0)
2639	ev_timer_stop (EV_A_ &to);	2916	ev_timer_stop (EV_A_ &to);
2640		2917
…		…
2718	if you do not want that, you need to temporarily stop the embed watcher).	2995	if you do not want that, you need to temporarily stop the embed watcher).
2719		2996
2720	=item ev_embed_sweep (loop, ev_embed *)	2997	=item ev_embed_sweep (loop, ev_embed *)
2721		2998
2722	Make a single, non-blocking sweep over the embedded loop. This works	2999	Make a single, non-blocking sweep over the embedded loop. This works
2723	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	3000	similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most
2724	appropriate way for embedded loops.	3001	appropriate way for embedded loops.
2725		3002
2726	=item struct ev_loop *other [read-only]	3003	=item struct ev_loop *other [read-only]
2727		3004
2728	The embedded event loop.	3005	The embedded event loop.
…		…
2788	C<ev_default_fork> cheats and calls it in the wrong process, the fork	3065	C<ev_default_fork> cheats and calls it in the wrong process, the fork
2789	handlers will be invoked, too, of course.	3066	handlers will be invoked, too, of course.
2790		3067
2791	=head3 The special problem of life after fork - how is it possible?	3068	=head3 The special problem of life after fork - how is it possible?
2792		3069
2793	Most uses of C<fork()> consist of forking, then some simple calls to ste	3070	Most uses of C<fork()> consist of forking, then some simple calls to set
2794	up/change the process environment, followed by a call to C<exec()>. This	3071	up/change the process environment, followed by a call to C<exec()>. This
2795	sequence should be handled by libev without any problems.	3072	sequence should be handled by libev without any problems.
2796		3073
2797	This changes when the application actually wants to do event handling	3074	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	3075	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	3091	disadvantage of having to use multiple event loops (which do not support
2815	signal watchers).	3092	signal watchers).
2816		3093
2817	When this is not possible, or you want to use the default loop for	3094	When this is not possible, or you want to use the default loop for
2818	other reasons, then in the process that wants to start "fresh", call	3095	other reasons, then in the process that wants to start "fresh", call
2819	C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying	3096	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	3097	Destroying the default loop will "orphan" (not stop) all registered
2821	have to be careful not to execute code that modifies those watchers. Note	3098	watchers, so you have to be careful not to execute code that modifies
2822	also that in that case, you have to re-register any signal watchers.	3099	those watchers. Note also that in that case, you have to re-register any
		3100	signal watchers.
2823		3101
2824	=head3 Watcher-Specific Functions and Data Members	3102	=head3 Watcher-Specific Functions and Data Members
2825		3103
2826	=over 4	3104	=over 4
2827		3105
2828	=item ev_fork_init (ev_signal *, callback)	3106	=item ev_fork_init (ev_fork *, callback)
2829		3107
2830	Initialises and configures the fork watcher - it has no parameters of any	3108	Initialises and configures the fork watcher - it has no parameters of any
2831	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,	3109	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
2832	believe me.	3110	really.
2833		3111
2834	=back	3112	=back
2835		3113
2836		3114
		3115	=head2 C<ev_cleanup> - even the best things end
		3116
		3117	Cleanup watchers are called just before the event loop is being destroyed
		3118	by a call to C<ev_loop_destroy>.
		3119
		3120	While there is no guarantee that the event loop gets destroyed, cleanup
		3121	watchers provide a convenient method to install cleanup hooks for your
		3122	program, worker threads and so on - you just to make sure to destroy the
		3123	loop when you want them to be invoked.
		3124
		3125	Cleanup watchers are invoked in the same way as any other watcher. Unlike
		3126	all other watchers, they do not keep a reference to the event loop (which
		3127	makes a lot of sense if you think about it). Like all other watchers, you
		3128	can call libev functions in the callback, except C<ev_cleanup_start>.
		3129
		3130	=head3 Watcher-Specific Functions and Data Members
		3131
		3132	=over 4
		3133
		3134	=item ev_cleanup_init (ev_cleanup *, callback)
		3135
		3136	Initialises and configures the cleanup watcher - it has no parameters of
		3137	any kind. There is a C<ev_cleanup_set> macro, but using it is utterly
		3138	pointless, I assure you.
		3139
		3140	=back
		3141
		3142	Example: Register an atexit handler to destroy the default loop, so any
		3143	cleanup functions are called.
		3144
		3145	static void
		3146	program_exits (void)
		3147	{
		3148	ev_loop_destroy (EV_DEFAULT_UC);
		3149	}
		3150
		3151	...
		3152	atexit (program_exits);
		3153
		3154
2837	=head2 C<ev_async> - how to wake up another event loop	3155	=head2 C<ev_async> - how to wake up an event loop
2838		3156
2839	In general, you cannot use an C<ev_loop> from multiple threads or other	3157	In general, you cannot use an C<ev_run> from multiple threads or other
2840	asynchronous sources such as signal handlers (as opposed to multiple event	3158	asynchronous sources such as signal handlers (as opposed to multiple event
2841	loops - those are of course safe to use in different threads).	3159	loops - those are of course safe to use in different threads).
2842		3160
2843	Sometimes, however, you need to wake up another event loop you do not	3161	Sometimes, however, you need to wake up an event loop you do not control,
2844	control, for example because it belongs to another thread. This is what	3162	for example because it belongs to another thread. This is what C<ev_async>
2845	C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you	3163	watchers do: as long as the C<ev_async> watcher is active, you can signal
2846	can signal it by calling C<ev_async_send>, which is thread- and signal	3164	it by calling C<ev_async_send>, which is thread- and signal safe.
2847	safe.
2848		3165
2849	This functionality is very similar to C<ev_signal> watchers, as signals,	3166	This functionality is very similar to C<ev_signal> watchers, as signals,
2850	too, are asynchronous in nature, and signals, too, will be compressed	3167	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	3168	(i.e. the number of callback invocations may be less than the number of
2852	C<ev_async_sent> calls).	3169	C<ev_async_sent> calls).
…		…
2857	=head3 Queueing	3174	=head3 Queueing
2858		3175
2859	C<ev_async> does not support queueing of data in any way. The reason	3176	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	3177	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	3178	multiple-writer-single-reader queue that works in all cases and doesn't
2862	need elaborate support such as pthreads.	3179	need elaborate support such as pthreads or unportable memory access
		3180	semantics.
2863		3181
2864	That means that if you want to queue data, you have to provide your own	3182	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	3183	queue. But at least I can tell you how to implement locking around your
2866	queue:	3184	queue:
2867		3185
…		…
3006		3324
3007	If C<timeout> is less than 0, then no timeout watcher will be	3325	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	3326	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and
3009	repeat = 0) will be started. C<0> is a valid timeout.	3327	repeat = 0) will be started. C<0> is a valid timeout.
3010		3328
3011	The callback has the type C<void (*cb)(int revents, void *arg)> and gets	3329	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	3330	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>	3331	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>	3332	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	3333	a timeout and an io event at the same time - you probably should give io
3016	events precedence.	3334	events precedence.
3017		3335
3018	Example: wait up to ten seconds for data to appear on STDIN_FILENO.	3336	Example: wait up to ten seconds for data to appear on STDIN_FILENO.
3019		3337
3020	static void stdin_ready (int revents, void *arg)	3338	static void stdin_ready (int revents, void *arg)
3021	{	3339	{
3022	if (revents & EV_READ)	3340	if (revents & EV_READ)
3023	/* stdin might have data for us, joy! */;	3341	/* stdin might have data for us, joy! */;
3024	else if (revents & EV_TIMEOUT)	3342	else if (revents & EV_TIMER)
3025	/* doh, nothing entered */;	3343	/* doh, nothing entered */;
3026	}	3344	}
3027		3345
3028	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	3346	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
3029		3347
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)	3348	=item ev_feed_fd_event (loop, int fd, int revents)
3037		3349
3038	Feed an event on the given fd, as if a file descriptor backend detected	3350	Feed an event on the given fd, as if a file descriptor backend detected
3039	the given events it.	3351	the given events it.
3040		3352
3041	=item ev_feed_signal_event (struct ev_loop *loop, int signum)	3353	=item ev_feed_signal_event (loop, int signum)
3042		3354
3043	Feed an event as if the given signal occurred (C<loop> must be the default	3355	Feed an event as if the given signal occurred (C<loop> must be the default
3044	loop!).	3356	loop!).
3045		3357
3046	=back	3358	=back
…		…
3126		3438
3127	=over 4	3439	=over 4
3128		3440
3129	=item ev::TYPE::TYPE ()	3441	=item ev::TYPE::TYPE ()
3130		3442
3131	=item ev::TYPE::TYPE (struct ev_loop *)	3443	=item ev::TYPE::TYPE (loop)
3132		3444
3133	=item ev::TYPE::~TYPE	3445	=item ev::TYPE::~TYPE
3134		3446
3135	The constructor (optionally) takes an event loop to associate the watcher	3447	The constructor (optionally) takes an event loop to associate the watcher
3136	with. If it is omitted, it will use C<EV_DEFAULT>.	3448	with. If it is omitted, it will use C<EV_DEFAULT>.
…		…
3169	myclass obj;	3481	myclass obj;
3170	ev::io iow;	3482	ev::io iow;
3171	iow.set <myclass, &myclass::io_cb> (&obj);	3483	iow.set <myclass, &myclass::io_cb> (&obj);
3172		3484
3173	=item w->set (object *)	3485	=item w->set (object *)
3174
3175	This is an B<experimental> feature that might go away in a future version.
3176		3486
3177	This is a variation of a method callback - leaving out the method to call	3487	This is a variation of a method callback - leaving out the method to call
3178	will default the method to C<operator ()>, which makes it possible to use	3488	will default the method to C<operator ()>, which makes it possible to use
3179	functor objects without having to manually specify the C<operator ()> all	3489	functor objects without having to manually specify the C<operator ()> all
3180	the time. Incidentally, you can then also leave out the template argument	3490	the time. Incidentally, you can then also leave out the template argument
…		…
3213	Example: Use a plain function as callback.	3523	Example: Use a plain function as callback.
3214		3524
3215	static void io_cb (ev::io &w, int revents) { }	3525	static void io_cb (ev::io &w, int revents) { }
3216	iow.set <io_cb> ();	3526	iow.set <io_cb> ();
3217		3527
3218	=item w->set (struct ev_loop *)	3528	=item w->set (loop)
3219		3529
3220	Associates a different C<struct ev_loop> with this watcher. You can only	3530	Associates a different C<struct ev_loop> with this watcher. You can only
3221	do this when the watcher is inactive (and not pending either).	3531	do this when the watcher is inactive (and not pending either).
3222		3532
3223	=item w->set ([arguments])	3533	=item w->set ([arguments])
3224		3534
3225	Basically the same as C<ev_TYPE_set>, with the same arguments. Must be	3535	Basically the same as C<ev_TYPE_set>, with the same arguments. Either this
3226	called at least once. Unlike the C counterpart, an active watcher gets	3536	method or a suitable start method must be called at least once. Unlike the
3227	automatically stopped and restarted when reconfiguring it with this	3537	C counterpart, an active watcher gets automatically stopped and restarted
3228	method.	3538	when reconfiguring it with this method.
3229		3539
3230	=item w->start ()	3540	=item w->start ()
3231		3541
3232	Starts the watcher. Note that there is no C<loop> argument, as the	3542	Starts the watcher. Note that there is no C<loop> argument, as the
3233	constructor already stores the event loop.	3543	constructor already stores the event loop.
3234		3544
		3545	=item w->start ([arguments])
		3546
		3547	Instead of calling C<set> and C<start> methods separately, it is often
		3548	convenient to wrap them in one call. Uses the same type of arguments as
		3549	the configure C<set> method of the watcher.
		3550
3235	=item w->stop ()	3551	=item w->stop ()
3236		3552
3237	Stops the watcher if it is active. Again, no C<loop> argument.	3553	Stops the watcher if it is active. Again, no C<loop> argument.
3238		3554
3239	=item w->again () (C<ev::timer>, C<ev::periodic> only)	3555	=item w->again () (C<ev::timer>, C<ev::periodic> only)
…		…
3251		3567
3252	=back	3568	=back
3253		3569
3254	=back	3570	=back
3255		3571
3256	Example: Define a class with an IO and idle watcher, start one of them in	3572	Example: Define a class with two I/O and idle watchers, start the I/O
3257	the constructor.	3573	watchers in the constructor.
3258		3574
3259	class myclass	3575	class myclass
3260	{	3576	{
3261	ev::io io ; void io_cb (ev::io &w, int revents);	3577	ev::io io ; void io_cb (ev::io &w, int revents);
		3578	ev::io2 io2 ; void io2_cb (ev::io &w, int revents);
3262	ev::idle idle; void idle_cb (ev::idle &w, int revents);	3579	ev::idle idle; void idle_cb (ev::idle &w, int revents);
3263		3580
3264	myclass (int fd)	3581	myclass (int fd)
3265	{	3582	{
3266	io .set <myclass, &myclass::io_cb > (this);	3583	io .set <myclass, &myclass::io_cb > (this);
		3584	io2 .set <myclass, &myclass::io2_cb > (this);
3267	idle.set <myclass, &myclass::idle_cb> (this);	3585	idle.set <myclass, &myclass::idle_cb> (this);
3268		3586
3269	io.start (fd, ev::READ);	3587	io.set (fd, ev::WRITE); // configure the watcher
		3588	io.start (); // start it whenever convenient
		3589
		3590	io2.start (fd, ev::READ); // set + start in one call
3270	}	3591	}
3271	};	3592	};
3272		3593
3273		3594
3274	=head1 OTHER LANGUAGE BINDINGS	3595	=head1 OTHER LANGUAGE BINDINGS
…		…
3320	=item Ocaml	3641	=item Ocaml
3321		3642
3322	Erkki Seppala has written Ocaml bindings for libev, to be found at	3643	Erkki Seppala has written Ocaml bindings for libev, to be found at
3323	L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>.	3644	L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>.
3324		3645
		3646	=item Lua
		3647
		3648	Brian Maher has written a partial interface to libev for lua (at the
		3649	time of this writing, only C<ev_io> and C<ev_timer>), to be found at
		3650	L<http://github.com/brimworks/lua-ev>.
		3651
3325	=back	3652	=back
3326		3653
3327		3654
3328	=head1 MACRO MAGIC	3655	=head1 MACRO MAGIC
3329		3656
…		…
3342	loop argument"). The C<EV_A> form is used when this is the sole argument,	3669	loop argument"). The C<EV_A> form is used when this is the sole argument,
3343	C<EV_A_> is used when other arguments are following. Example:	3670	C<EV_A_> is used when other arguments are following. Example:
3344		3671
3345	ev_unref (EV_A);	3672	ev_unref (EV_A);
3346	ev_timer_add (EV_A_ watcher);	3673	ev_timer_add (EV_A_ watcher);
3347	ev_loop (EV_A_ 0);	3674	ev_run (EV_A_ 0);
3348		3675
3349	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	3676	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
3350	which is often provided by the following macro.	3677	which is often provided by the following macro.
3351		3678
3352	=item C<EV_P>, C<EV_P_>	3679	=item C<EV_P>, C<EV_P_>
…		…
3392	}	3719	}
3393		3720
3394	ev_check check;	3721	ev_check check;
3395	ev_check_init (&check, check_cb);	3722	ev_check_init (&check, check_cb);
3396	ev_check_start (EV_DEFAULT_ &check);	3723	ev_check_start (EV_DEFAULT_ &check);
3397	ev_loop (EV_DEFAULT_ 0);	3724	ev_run (EV_DEFAULT_ 0);
3398		3725
3399	=head1 EMBEDDING	3726	=head1 EMBEDDING
3400		3727
3401	Libev can (and often is) directly embedded into host	3728	Libev can (and often is) directly embedded into host
3402	applications. Examples of applications that embed it include the Deliantra	3729	applications. Examples of applications that embed it include the Deliantra
…		…
3482	libev.m4	3809	libev.m4
3483		3810
3484	=head2 PREPROCESSOR SYMBOLS/MACROS	3811	=head2 PREPROCESSOR SYMBOLS/MACROS
3485		3812
3486	Libev can be configured via a variety of preprocessor symbols you have to	3813	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	3814	define before including (or compiling) any of its files. The default in
3488	autoconf is documented for every option.	3815	the absence of autoconf is documented for every option.
		3816
		3817	Symbols marked with "(h)" do not change the ABI, and can have different
		3818	values when compiling libev vs. including F<ev.h>, so it is permissible
		3819	to redefine them before including F<ev.h> without breaking compatibility
		3820	to a compiled library. All other symbols change the ABI, which means all
		3821	users of libev and the libev code itself must be compiled with compatible
		3822	settings.
3489		3823
3490	=over 4	3824	=over 4
3491		3825
		3826	=item EV_COMPAT3 (h)
		3827
		3828	Backwards compatibility is a major concern for libev. This is why this
		3829	release of libev comes with wrappers for the functions and symbols that
		3830	have been renamed between libev version 3 and 4.
		3831
		3832	You can disable these wrappers (to test compatibility with future
		3833	versions) by defining C<EV_COMPAT3> to C<0> when compiling your
		3834	sources. This has the additional advantage that you can drop the C<struct>
		3835	from C<struct ev_loop> declarations, as libev will provide an C<ev_loop>
		3836	typedef in that case.
		3837
		3838	In some future version, the default for C<EV_COMPAT3> will become C<0>,
		3839	and in some even more future version the compatibility code will be
		3840	removed completely.
		3841
3492	=item EV_STANDALONE	3842	=item EV_STANDALONE (h)
3493		3843
3494	Must always be C<1> if you do not use autoconf configuration, which	3844	Must always be C<1> if you do not use autoconf configuration, which
3495	keeps libev from including F<config.h>, and it also defines dummy	3845	keeps libev from including F<config.h>, and it also defines dummy
3496	implementations for some libevent functions (such as logging, which is not	3846	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	3847	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.	3848	F<event.h> that are not directly supported by the libev core alone.
3499		3849
3500	In stanbdalone mode, libev will still try to automatically deduce the	3850	In standalone mode, libev will still try to automatically deduce the
3501	configuration, but has to be more conservative.	3851	configuration, but has to be more conservative.
3502		3852
3503	=item EV_USE_MONOTONIC	3853	=item EV_USE_MONOTONIC
3504		3854
3505	If defined to be C<1>, libev will try to detect the availability of the	3855	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	3920	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,	3921	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	3922	it is assumed that all these functions actually work on fds, even
3573	on win32. Should not be defined on non-win32 platforms.	3923	on win32. Should not be defined on non-win32 platforms.
3574		3924
3575	=item EV_FD_TO_WIN32_HANDLE	3925	=item EV_FD_TO_WIN32_HANDLE(fd)
3576		3926
3577	If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map	3927	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	3928	file descriptors to socket handles. When not defining this symbol (the
3579	default), then libev will call C<_get_osfhandle>, which is usually	3929	default), then libev will call C<_get_osfhandle>, which is usually
3580	correct. In some cases, programs use their own file descriptor management,	3930	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.	3931	in which case they can provide this function to map fds to socket handles.
		3932
		3933	=item EV_WIN32_HANDLE_TO_FD(handle)
		3934
		3935	If C<EV_SELECT_IS_WINSOCKET> then libev maps handles to file descriptors
		3936	using the standard C<_open_osfhandle> function. For programs implementing
		3937	their own fd to handle mapping, overwriting this function makes it easier
		3938	to do so. This can be done by defining this macro to an appropriate value.
		3939
		3940	=item EV_WIN32_CLOSE_FD(fd)
		3941
		3942	If programs implement their own fd to handle mapping on win32, then this
		3943	macro can be used to override the C<close> function, useful to unregister
		3944	file descriptors again. Note that the replacement function has to close
		3945	the underlying OS handle.
3582		3946
3583	=item EV_USE_POLL	3947	=item EV_USE_POLL
3584		3948
3585	If defined to be C<1>, libev will compile in support for the C<poll>(2)	3949	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	3950	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.	3997	as well as for signal and thread safety in C<ev_async> watchers.
3634		3998
3635	In the absence of this define, libev will use C<sig_atomic_t volatile>	3999	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.	4000	(from F<signal.h>), which is usually good enough on most platforms.
3637		4001
3638	=item EV_H	4002	=item EV_H (h)
3639		4003
3640	The name of the F<ev.h> header file used to include it. The default if	4004	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	4005	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.	4006	used to virtually rename the F<ev.h> header file in case of conflicts.
3643		4007
3644	=item EV_CONFIG_H	4008	=item EV_CONFIG_H (h)
3645		4009
3646	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override	4010	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	4011	F<ev.c>'s idea of where to find the F<config.h> file, similarly to
3648	C<EV_H>, above.	4012	C<EV_H>, above.
3649		4013
3650	=item EV_EVENT_H	4014	=item EV_EVENT_H (h)
3651		4015
3652	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea	4016	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">.	4017	of how the F<event.h> header can be found, the default is C<"event.h">.
3654		4018
3655	=item EV_PROTOTYPES	4019	=item EV_PROTOTYPES (h)
3656		4020
3657	If defined to be C<0>, then F<ev.h> will not define any function	4021	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	4022	prototypes, but still define all the structs and other symbols. This is
3659	occasionally useful if you want to provide your own wrapper functions	4023	occasionally useful if you want to provide your own wrapper functions
3660	around libev functions.	4024	around libev functions.
…		…
3682	fine.	4046	fine.
3683		4047
3684	If your embedding application does not need any priorities, defining these	4048	If your embedding application does not need any priorities, defining these
3685	both to C<0> will save some memory and CPU.	4049	both to C<0> will save some memory and CPU.
3686		4050
3687	=item EV_PERIODIC_ENABLE	4051	=item EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE,
		4052	EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE,
		4053	EV_ASYNC_ENABLE, EV_CHILD_ENABLE.
3688		4054
3689	If undefined or defined to be C<1>, then periodic timers are supported. If	4055	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	4056	the respective watcher type is supported. If defined to be C<0>, then it
3691	code.	4057	is not. Disabling watcher types mainly saves code size.
3692		4058
3693	=item EV_IDLE_ENABLE	4059	=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		4060
3722	If you need to shave off some kilobytes of code at the expense of some	4061	If you need to shave off some kilobytes of code at the expense of some
3723	speed (but with the full API), define this symbol to C<1>. Currently this	4062	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	4063	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	4064	that can be enabled on the platform.
3726	the default 4-heap.
3727		4065
3728	You can save even more by disabling watcher types you do not need	4066	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>	4067	with some broad features you want) and then selectively re-enable
3730	(C<-DNDEBUG>) will usually reduce code size a lot.	4068	additional parts you want, for example if you want everything minimal,
		4069	but multiple event loop support, async and child watchers and the poll
		4070	backend, use this:
3731		4071
3732	Defining C<EV_MINIMAL> to C<2> will additionally reduce the core API to	4072	#define EV_FEATURES 0
3733	provide a bare-bones event library. See C<ev.h> for details on what parts	4073	#define EV_MULTIPLICITY 1
3734	of the API are still available, and do not complain if this subset changes	4074	#define EV_USE_POLL 1
3735	over time.	4075	#define EV_CHILD_ENABLE 1
		4076	#define EV_ASYNC_ENABLE 1
		4077
		4078	The actual value is a bitset, it can be a combination of the following
		4079	values:
		4080
		4081	=over 4
		4082
		4083	=item C<1> - faster/larger code
		4084
		4085	Use larger code to speed up some operations.
		4086
		4087	Currently this is used to override some inlining decisions (enlarging the
		4088	code size by roughly 30% on amd64).
		4089
		4090	When optimising for size, use of compiler flags such as C<-Os> with
		4091	gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of
		4092	assertions.
		4093
		4094	=item C<2> - faster/larger data structures
		4095
		4096	Replaces the small 2-heap for timer management by a faster 4-heap, larger
		4097	hash table sizes and so on. This will usually further increase code size
		4098	and can additionally have an effect on the size of data structures at
		4099	runtime.
		4100
		4101	=item C<4> - full API configuration
		4102
		4103	This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and
		4104	enables multiplicity (C<EV_MULTIPLICITY>=1).
		4105
		4106	=item C<8> - full API
		4107
		4108	This enables a lot of the "lesser used" API functions. See C<ev.h> for
		4109	details on which parts of the API are still available without this
		4110	feature, and do not complain if this subset changes over time.
		4111
		4112	=item C<16> - enable all optional watcher types
		4113
		4114	Enables all optional watcher types. If you want to selectively enable
		4115	only some watcher types other than I/O and timers (e.g. prepare,
		4116	embed, async, child...) you can enable them manually by defining
		4117	C<EV_watchertype_ENABLE> to C<1> instead.
		4118
		4119	=item C<32> - enable all backends
		4120
		4121	This enables all backends - without this feature, you need to enable at
		4122	least one backend manually (C<EV_USE_SELECT> is a good choice).
		4123
		4124	=item C<64> - enable OS-specific "helper" APIs
		4125
		4126	Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by
		4127	default.
		4128
		4129	=back
		4130
		4131	Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0>
		4132	reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb
		4133	code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O
		4134	watchers, timers and monotonic clock support.
		4135
		4136	With an intelligent-enough linker (gcc+binutils are intelligent enough
		4137	when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by
		4138	your program might be left out as well - a binary starting a timer and an
		4139	I/O watcher then might come out at only 5Kb.
		4140
		4141	=item EV_AVOID_STDIO
		4142
		4143	If this is set to C<1> at compiletime, then libev will avoid using stdio
		4144	functions (printf, scanf, perror etc.). This will increase the code size
		4145	somewhat, but if your program doesn't otherwise depend on stdio and your
		4146	libc allows it, this avoids linking in the stdio library which is quite
		4147	big.
		4148
		4149	Note that error messages might become less precise when this option is
		4150	enabled.
		4151
		4152	=item EV_NSIG
		4153
		4154	The highest supported signal number, +1 (or, the number of
		4155	signals): Normally, libev tries to deduce the maximum number of signals
		4156	automatically, but sometimes this fails, in which case it can be
		4157	specified. Also, using a lower number than detected (C<32> should be
		4158	good for about any system in existence) can save some memory, as libev
		4159	statically allocates some 12-24 bytes per signal number.
3736		4160
3737	=item EV_PID_HASHSIZE	4161	=item EV_PID_HASHSIZE
3738		4162
3739	C<ev_child> watchers use a small hash table to distribute workload by	4163	C<ev_child> watchers use a small hash table to distribute workload by
3740	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more	4164	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	4165	usually more than enough. If you need to manage thousands of children you
3742	increase this value (I<must> be a power of two).	4166	might want to increase this value (I<must> be a power of two).
3743		4167
3744	=item EV_INOTIFY_HASHSIZE	4168	=item EV_INOTIFY_HASHSIZE
3745		4169
3746	C<ev_stat> watchers use a small hash table to distribute workload by	4170	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>),	4171	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>	4172	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	4173	C<ev_stat> watchers you might want to increase this value (I<must> be a
3750	two).	4174	power of two).
3751		4175
3752	=item EV_USE_4HEAP	4176	=item EV_USE_4HEAP
3753		4177
3754	Heaps are not very cache-efficient. To improve the cache-efficiency of the	4178	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	4179	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	4180	to C<1>. The 4-heap uses more complicated (longer) code but has noticeably
3757	faster performance with many (thousands) of watchers.	4181	faster performance with many (thousands) of watchers.
3758		4182
3759	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>	4183	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3760	(disabled).	4184	will be C<0>.
3761		4185
3762	=item EV_HEAP_CACHE_AT	4186	=item EV_HEAP_CACHE_AT
3763		4187
3764	Heaps are not very cache-efficient. To improve the cache-efficiency of the	4188	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	4189	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>),	4190	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,	4191	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	4192	but avoids random read accesses on heap changes. This improves performance
3769	noticeably with many (hundreds) of watchers.	4193	noticeably with many (hundreds) of watchers.
3770		4194
3771	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>	4195	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3772	(disabled).	4196	will be C<0>.
3773		4197
3774	=item EV_VERIFY	4198	=item EV_VERIFY
3775		4199
3776	Controls how much internal verification (see C<ev_loop_verify ()>) will	4200	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	4201	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	4202	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	4203	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	4204	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	4205	verification code will be called very frequently, which will slow down
3782	libev considerably.	4206	libev considerably.
3783		4207
3784	The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be	4208	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3785	C<0>.	4209	will be C<0>.
3786		4210
3787	=item EV_COMMON	4211	=item EV_COMMON
3788		4212
3789	By default, all watchers have a C<void *data> member. By redefining	4213	By default, all watchers have a C<void *data> member. By redefining
3790	this macro to a something else you can include more and other types of	4214	this macro to something else you can include more and other types of
3791	members. You have to define it each time you include one of the files,	4215	members. You have to define it each time you include one of the files,
3792	though, and it must be identical each time.	4216	though, and it must be identical each time.
3793		4217
3794	For example, the perl EV module uses something like this:	4218	For example, the perl EV module uses something like this:
3795		4219
…		…
3848	file.	4272	file.
3849		4273
3850	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	4274	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:	4275	that everybody includes and which overrides some configure choices:
3852		4276
3853	#define EV_MINIMAL 1	4277	#define EV_FEATURES 8
3854	#define EV_USE_POLL 0	4278	#define EV_USE_SELECT 1
3855	#define EV_MULTIPLICITY 0
3856	#define EV_PERIODIC_ENABLE 0	4279	#define EV_PREPARE_ENABLE 1
		4280	#define EV_IDLE_ENABLE 1
3857	#define EV_STAT_ENABLE 0	4281	#define EV_SIGNAL_ENABLE 1
3858	#define EV_FORK_ENABLE 0	4282	#define EV_CHILD_ENABLE 1
		4283	#define EV_USE_STDEXCEPT 0
3859	#define EV_CONFIG_H <config.h>	4284	#define EV_CONFIG_H <config.h>
3860	#define EV_MINPRI 0
3861	#define EV_MAXPRI 0
3862		4285
3863	#include "ev++.h"	4286	#include "ev++.h"
3864		4287
3865	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	4288	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
3866		4289
…		…
3928		4351
3929	=back	4352	=back
3930		4353
3931	=head4 THREAD LOCKING EXAMPLE	4354	=head4 THREAD LOCKING EXAMPLE
3932		4355
		4356	Here is a fictitious example of how to run an event loop in a different
		4357	thread than where callbacks are being invoked and watchers are
		4358	created/added/removed.
		4359
		4360	For a real-world example, see the C<EV::Loop::Async> perl module,
		4361	which uses exactly this technique (which is suited for many high-level
		4362	languages).
		4363
		4364	The example uses a pthread mutex to protect the loop data, a condition
		4365	variable to wait for callback invocations, an async watcher to notify the
		4366	event loop thread and an unspecified mechanism to wake up the main thread.
		4367
		4368	First, you need to associate some data with the event loop:
		4369
		4370	typedef struct {
		4371	mutex_t lock; /* global loop lock */
		4372	ev_async async_w;
		4373	thread_t tid;
		4374	cond_t invoke_cv;
		4375	} userdata;
		4376
		4377	void prepare_loop (EV_P)
		4378	{
		4379	// for simplicity, we use a static userdata struct.
		4380	static userdata u;
		4381
		4382	ev_async_init (&u->async_w, async_cb);
		4383	ev_async_start (EV_A_ &u->async_w);
		4384
		4385	pthread_mutex_init (&u->lock, 0);
		4386	pthread_cond_init (&u->invoke_cv, 0);
		4387
		4388	// now associate this with the loop
		4389	ev_set_userdata (EV_A_ u);
		4390	ev_set_invoke_pending_cb (EV_A_ l_invoke);
		4391	ev_set_loop_release_cb (EV_A_ l_release, l_acquire);
		4392
		4393	// then create the thread running ev_loop
		4394	pthread_create (&u->tid, 0, l_run, EV_A);
		4395	}
		4396
		4397	The callback for the C<ev_async> watcher does nothing: the watcher is used
		4398	solely to wake up the event loop so it takes notice of any new watchers
		4399	that might have been added:
		4400
		4401	static void
		4402	async_cb (EV_P_ ev_async *w, int revents)
		4403	{
		4404	// just used for the side effects
		4405	}
		4406
		4407	The C<l_release> and C<l_acquire> callbacks simply unlock/lock the mutex
		4408	protecting the loop data, respectively.
		4409
		4410	static void
		4411	l_release (EV_P)
		4412	{
		4413	userdata *u = ev_userdata (EV_A);
		4414	pthread_mutex_unlock (&u->lock);
		4415	}
		4416
		4417	static void
		4418	l_acquire (EV_P)
		4419	{
		4420	userdata *u = ev_userdata (EV_A);
		4421	pthread_mutex_lock (&u->lock);
		4422	}
		4423
		4424	The event loop thread first acquires the mutex, and then jumps straight
		4425	into C<ev_run>:
		4426
		4427	void *
		4428	l_run (void *thr_arg)
		4429	{
		4430	struct ev_loop *loop = (struct ev_loop *)thr_arg;
		4431
		4432	l_acquire (EV_A);
		4433	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
		4434	ev_run (EV_A_ 0);
		4435	l_release (EV_A);
		4436
		4437	return 0;
		4438	}
		4439
		4440	Instead of invoking all pending watchers, the C<l_invoke> callback will
		4441	signal the main thread via some unspecified mechanism (signals? pipe
		4442	writes? C<Async::Interrupt>?) and then waits until all pending watchers
		4443	have been called (in a while loop because a) spurious wakeups are possible
		4444	and b) skipping inter-thread-communication when there are no pending
		4445	watchers is very beneficial):
		4446
		4447	static void
		4448	l_invoke (EV_P)
		4449	{
		4450	userdata *u = ev_userdata (EV_A);
		4451
		4452	while (ev_pending_count (EV_A))
		4453	{
		4454	wake_up_other_thread_in_some_magic_or_not_so_magic_way ();
		4455	pthread_cond_wait (&u->invoke_cv, &u->lock);
		4456	}
		4457	}
		4458
		4459	Now, whenever the main thread gets told to invoke pending watchers, it
		4460	will grab the lock, call C<ev_invoke_pending> and then signal the loop
		4461	thread to continue:
		4462
		4463	static void
		4464	real_invoke_pending (EV_P)
		4465	{
		4466	userdata *u = ev_userdata (EV_A);
		4467
		4468	pthread_mutex_lock (&u->lock);
		4469	ev_invoke_pending (EV_A);
		4470	pthread_cond_signal (&u->invoke_cv);
		4471	pthread_mutex_unlock (&u->lock);
		4472	}
		4473
		4474	Whenever you want to start/stop a watcher or do other modifications to an
		4475	event loop, you will now have to lock:
		4476
		4477	ev_timer timeout_watcher;
		4478	userdata *u = ev_userdata (EV_A);
		4479
		4480	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
		4481
		4482	pthread_mutex_lock (&u->lock);
		4483	ev_timer_start (EV_A_ &timeout_watcher);
		4484	ev_async_send (EV_A_ &u->async_w);
		4485	pthread_mutex_unlock (&u->lock);
		4486
		4487	Note that sending the C<ev_async> watcher is required because otherwise
		4488	an event loop currently blocking in the kernel will have no knowledge
		4489	about the newly added timer. By waking up the loop it will pick up any new
		4490	watchers in the next event loop iteration.
		4491
3933	=head3 COROUTINES	4492	=head3 COROUTINES
3934		4493
3935	Libev is very accommodating to coroutines ("cooperative threads"):	4494	Libev is very accommodating to coroutines ("cooperative threads"):
3936	libev fully supports nesting calls to its functions from different	4495	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	4496	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	4497	different coroutines, and switch freely between both coroutines running
3939	loop, as long as you don't confuse yourself). The only exception is that	4498	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.	4499	that you must not do this from C<ev_periodic> reschedule callbacks.
3941		4500
3942	Care has been taken to ensure that libev does not keep local state inside	4501	Care has been taken to ensure that libev does not keep local state inside
3943	C<ev_loop>, and other calls do not usually allow for coroutine switches as	4502	C<ev_run>, and other calls do not usually allow for coroutine switches as
3944	they do not call any callbacks.	4503	they do not call any callbacks.
3945		4504
3946	=head2 COMPILER WARNINGS	4505	=head2 COMPILER WARNINGS
3947		4506
3948	Depending on your compiler and compiler settings, you might get no or a	4507	Depending on your compiler and compiler settings, you might get no or a
…		…
3959	maintainable.	4518	maintainable.
3960		4519
3961	And of course, some compiler warnings are just plain stupid, or simply	4520	And of course, some compiler warnings are just plain stupid, or simply
3962	wrong (because they don't actually warn about the condition their message	4521	wrong (because they don't actually warn about the condition their message
3963	seems to warn about). For example, certain older gcc versions had some	4522	seems to warn about). For example, certain older gcc versions had some
3964	warnings that resulted an extreme number of false positives. These have	4523	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	4524	been fixed, but some people still insist on making code warn-free with
3966	such buggy versions.	4525	such buggy versions.
3967		4526
3968	While libev is written to generate as few warnings as possible,	4527	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	4528	"warn-free" code is not a goal, and it is recommended not to build libev
…		…
4005	I suggest using suppression lists.	4564	I suggest using suppression lists.
4006		4565
4007		4566
4008	=head1 PORTABILITY NOTES	4567	=head1 PORTABILITY NOTES
4009		4568
		4569	=head2 GNU/LINUX 32 BIT LIMITATIONS
		4570
		4571	GNU/Linux is the only common platform that supports 64 bit file/large file
		4572	interfaces but I<disables> them by default.
		4573
		4574	That means that libev compiled in the default environment doesn't support
		4575	files larger than 2GiB or so, which mainly affects C<ev_stat> watchers.
		4576
		4577	Unfortunately, many programs try to work around this GNU/Linux issue
		4578	by enabling the large file API, which makes them incompatible with the
		4579	standard libev compiled for their system.
		4580
		4581	Likewise, libev cannot enable the large file API itself as this would
		4582	suddenly make it incompatible to the default compile time environment,
		4583	i.e. all programs not using special compile switches.
		4584
		4585	=head2 OS/X AND DARWIN BUGS
		4586
		4587	The whole thing is a bug if you ask me - basically any system interface
		4588	you touch is broken, whether it is locales, poll, kqueue or even the
		4589	OpenGL drivers.
		4590
		4591	=head3 C<kqueue> is buggy
		4592
		4593	The kqueue syscall is broken in all known versions - most versions support
		4594	only sockets, many support pipes.
		4595
		4596	Libev tries to work around this by not using C<kqueue> by default on this
		4597	rotten platform, but of course you can still ask for it when creating a
		4598	loop - embedding a socket-only kqueue loop into a select-based one is
		4599	probably going to work well.
		4600
		4601	=head3 C<poll> is buggy
		4602
		4603	Instead of fixing C<kqueue>, Apple replaced their (working) C<poll>
		4604	implementation by something calling C<kqueue> internally around the 10.5.6
		4605	release, so now C<kqueue> I<and> C<poll> are broken.
		4606
		4607	Libev tries to work around this by not using C<poll> by default on
		4608	this rotten platform, but of course you can still ask for it when creating
		4609	a loop.
		4610
		4611	=head3 C<select> is buggy
		4612
		4613	All that's left is C<select>, and of course Apple found a way to fuck this
		4614	one up as well: On OS/X, C<select> actively limits the number of file
		4615	descriptors you can pass in to 1024 - your program suddenly crashes when
		4616	you use more.
		4617
		4618	There is an undocumented "workaround" for this - defining
		4619	C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should>
		4620	work on OS/X.
		4621
		4622	=head2 SOLARIS PROBLEMS AND WORKAROUNDS
		4623
		4624	=head3 C<errno> reentrancy
		4625
		4626	The default compile environment on Solaris is unfortunately so
		4627	thread-unsafe that you can't even use components/libraries compiled
		4628	without C<-D_REENTRANT> in a threaded program, which, of course, isn't
		4629	defined by default. A valid, if stupid, implementation choice.
		4630
		4631	If you want to use libev in threaded environments you have to make sure
		4632	it's compiled with C<_REENTRANT> defined.
		4633
		4634	=head3 Event port backend
		4635
		4636	The scalable event interface for Solaris is called "event
		4637	ports". Unfortunately, this mechanism is very buggy in all major
		4638	releases. If you run into high CPU usage, your program freezes or you get
		4639	a large number of spurious wakeups, make sure you have all the relevant
		4640	and latest kernel patches applied. No, I don't know which ones, but there
		4641	are multiple ones to apply, and afterwards, event ports actually work
		4642	great.
		4643
		4644	If you can't get it to work, you can try running the program by setting
		4645	the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and
		4646	C<select> backends.
		4647
		4648	=head2 AIX POLL BUG
		4649
		4650	AIX unfortunately has a broken C<poll.h> header. Libev works around
		4651	this by trying to avoid the poll backend altogether (i.e. it's not even
		4652	compiled in), which normally isn't a big problem as C<select> works fine
		4653	with large bitsets on AIX, and AIX is dead anyway.
		4654
4010	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS	4655	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
		4656
		4657	=head3 General issues
4011		4658
4012	Win32 doesn't support any of the standards (e.g. POSIX) that libev	4659	Win32 doesn't support any of the standards (e.g. POSIX) that libev
4013	requires, and its I/O model is fundamentally incompatible with the POSIX	4660	requires, and its I/O model is fundamentally incompatible with the POSIX
4014	model. Libev still offers limited functionality on this platform in	4661	model. Libev still offers limited functionality on this platform in
4015	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	4662	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
4016	descriptors. This only applies when using Win32 natively, not when using	4663	descriptors. This only applies when using Win32 natively, not when using
4017	e.g. cygwin.	4664	e.g. cygwin. Actually, it only applies to the microsofts own compilers,
		4665	as every compielr comes with a slightly differently broken/incompatible
		4666	environment.
4018		4667
4019	Lifting these limitations would basically require the full	4668	Lifting these limitations would basically require the full
4020	re-implementation of the I/O system. If you are into these kinds of	4669	re-implementation of the I/O system. If you are into this kind of thing,
4021	things, then note that glib does exactly that for you in a very portable	4670	then note that glib does exactly that for you in a very portable way (note
4022	way (note also that glib is the slowest event library known to man).	4671	also that glib is the slowest event library known to man).
4023		4672
4024	There is no supported compilation method available on windows except	4673	There is no supported compilation method available on windows except
4025	embedding it into other applications.	4674	embedding it into other applications.
4026		4675
4027	Sensible signal handling is officially unsupported by Microsoft - libev	4676	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!):	4704	you do I<not> compile the F<ev.c> or any other embedded source files!):
4056		4705
4057	#include "evwrap.h"	4706	#include "evwrap.h"
4058	#include "ev.c"	4707	#include "ev.c"
4059		4708
4060	=over 4
4061
4062	=item The winsocket select function	4709	=head3 The winsocket C<select> function
4063		4710
4064	The winsocket C<select> function doesn't follow POSIX in that it	4711	The winsocket C<select> function doesn't follow POSIX in that it
4065	requires socket I<handles> and not socket I<file descriptors> (it is	4712	requires socket I<handles> and not socket I<file descriptors> (it is
4066	also extremely buggy). This makes select very inefficient, and also	4713	also extremely buggy). This makes select very inefficient, and also
4067	requires a mapping from file descriptors to socket handles (the Microsoft	4714	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 */	4723	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
4077		4724
4078	Note that winsockets handling of fd sets is O(n), so you can easily get a	4725	Note that winsockets handling of fd sets is O(n), so you can easily get a
4079	complexity in the O(n²) range when using win32.	4726	complexity in the O(n²) range when using win32.
4080		4727
4081	=item Limited number of file descriptors	4728	=head3 Limited number of file descriptors
4082		4729
4083	Windows has numerous arbitrary (and low) limits on things.	4730	Windows has numerous arbitrary (and low) limits on things.
4084		4731
4085	Early versions of winsocket's select only supported waiting for a maximum	4732	Early versions of winsocket's select only supported waiting for a maximum
4086	of C<64> handles (probably owning to the fact that all windows kernels	4733	of C<64> handles (probably owning to the fact that all windows kernels
…		…
4101	runtime libraries. This might get you to about C<512> or C<2048> sockets	4748	runtime libraries. This might get you to about C<512> or C<2048> sockets
4102	(depending on windows version and/or the phase of the moon). To get more,	4749	(depending on windows version and/or the phase of the moon). To get more,
4103	you need to wrap all I/O functions and provide your own fd management, but	4750	you need to wrap all I/O functions and provide your own fd management, but
4104	the cost of calling select (O(n²)) will likely make this unworkable.	4751	the cost of calling select (O(n²)) will likely make this unworkable.
4105		4752
4106	=back
4107
4108	=head2 PORTABILITY REQUIREMENTS	4753	=head2 PORTABILITY REQUIREMENTS
4109		4754
4110	In addition to a working ISO-C implementation and of course the	4755	In addition to a working ISO-C implementation and of course the
4111	backend-specific APIs, libev relies on a few additional extensions:	4756	backend-specific APIs, libev relies on a few additional extensions:
4112		4757
…		…
4118	Libev assumes not only that all watcher pointers have the same internal	4763	Libev assumes not only that all watcher pointers have the same internal
4119	structure (guaranteed by POSIX but not by ISO C for example), but it also	4764	structure (guaranteed by POSIX but not by ISO C for example), but it also
4120	assumes that the same (machine) code can be used to call any watcher	4765	assumes that the same (machine) code can be used to call any watcher
4121	callback: The watcher callbacks have different type signatures, but libev	4766	callback: The watcher callbacks have different type signatures, but libev
4122	calls them using an C<ev_watcher *> internally.	4767	calls them using an C<ev_watcher *> internally.
		4768
		4769	=item pointer accesses must be thread-atomic
		4770
		4771	Accessing a pointer value must be atomic, it must both be readable and
		4772	writable in one piece - this is the case on all current architectures.
4123		4773
4124	=item C<sig_atomic_t volatile> must be thread-atomic as well	4774	=item C<sig_atomic_t volatile> must be thread-atomic as well
4125		4775
4126	The type C<sig_atomic_t volatile> (or whatever is defined as	4776	The type C<sig_atomic_t volatile> (or whatever is defined as
4127	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different	4777	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different
…		…
4150	watchers.	4800	watchers.
4151		4801
4152	=item C<double> must hold a time value in seconds with enough accuracy	4802	=item C<double> must hold a time value in seconds with enough accuracy
4153		4803
4154	The type C<double> is used to represent timestamps. It is required to	4804	The type C<double> is used to represent timestamps. It is required to
4155	have at least 51 bits of mantissa (and 9 bits of exponent), which is good	4805	have at least 51 bits of mantissa (and 9 bits of exponent), which is
4156	enough for at least into the year 4000. This requirement is fulfilled by	4806	good enough for at least into the year 4000 with millisecond accuracy
		4807	(the design goal for libev). This requirement is overfulfilled by
4157	implementations implementing IEEE 754, which is basically all existing	4808	implementations using IEEE 754, which is basically all existing ones. With
4158	ones. With IEEE 754 doubles, you get microsecond accuracy until at least	4809	IEEE 754 doubles, you get microsecond accuracy until at least 2200.
4159	2200.
4160		4810
4161	=back	4811	=back
4162		4812
4163	If you know of other additional requirements drop me a note.	4813	If you know of other additional requirements drop me a note.
4164		4814
…		…
4232	involves iterating over all running async watchers or all signal numbers.	4882	involves iterating over all running async watchers or all signal numbers.
4233		4883
4234	=back	4884	=back
4235		4885
4236		4886
		4887	=head1 PORTING FROM LIBEV 3.X TO 4.X
		4888
		4889	The major version 4 introduced some incompatible changes to the API.
		4890
		4891	At the moment, the C<ev.h> header file provides compatibility definitions
		4892	for all changes, so most programs should still compile. The compatibility
		4893	layer might be removed in later versions of libev, so better update to the
		4894	new API early than late.
		4895
		4896	=over 4
		4897
		4898	=item C<EV_COMPAT3> backwards compatibility mechanism
		4899
		4900	The backward compatibility mechanism can be controlled by
		4901	C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING>
		4902	section.
		4903
		4904	=item C<ev_default_destroy> and C<ev_default_fork> have been removed
		4905
		4906	These calls can be replaced easily by their C<ev_loop_xxx> counterparts:
		4907
		4908	ev_loop_destroy (EV_DEFAULT_UC);
		4909	ev_loop_fork (EV_DEFAULT);
		4910
		4911	=item function/symbol renames
		4912
		4913	A number of functions and symbols have been renamed:
		4914
		4915	ev_loop => ev_run
		4916	EVLOOP_NONBLOCK => EVRUN_NOWAIT
		4917	EVLOOP_ONESHOT => EVRUN_ONCE
		4918
		4919	ev_unloop => ev_break
		4920	EVUNLOOP_CANCEL => EVBREAK_CANCEL
		4921	EVUNLOOP_ONE => EVBREAK_ONE
		4922	EVUNLOOP_ALL => EVBREAK_ALL
		4923
		4924	EV_TIMEOUT => EV_TIMER
		4925
		4926	ev_loop_count => ev_iteration
		4927	ev_loop_depth => ev_depth
		4928	ev_loop_verify => ev_verify
		4929
		4930	Most functions working on C<struct ev_loop> objects don't have an
		4931	C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and
		4932	associated constants have been renamed to not collide with the C<struct
		4933	ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme
		4934	as all other watcher types. Note that C<ev_loop_fork> is still called
		4935	C<ev_loop_fork> because it would otherwise clash with the C<ev_fork>
		4936	typedef.
		4937
		4938	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>
		4939
		4940	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different
		4941	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile
		4942	and work, but the library code will of course be larger.
		4943
		4944	=back
		4945
		4946
4237	=head1 GLOSSARY	4947	=head1 GLOSSARY
4238		4948
4239	=over 4	4949	=over 4
4240		4950
4241	=item active	4951	=item active
4242		4952
4243	A watcher is active as long as it has been started (has been attached to	4953	A watcher is active as long as it has been started and not yet stopped.
4244	an event loop) but not yet stopped (disassociated from the event loop).	4954	See L<WATCHER STATES> for details.
4245		4955
4246	=item application	4956	=item application
4247		4957
4248	In this document, an application is whatever is using libev.	4958	In this document, an application is whatever is using libev.
		4959
		4960	=item backend
		4961
		4962	The part of the code dealing with the operating system interfaces.
4249		4963
4250	=item callback	4964	=item callback
4251		4965
4252	The address of a function that is called when some event has been	4966	The address of a function that is called when some event has been
4253	detected. Callbacks are being passed the event loop, the watcher that	4967	detected. Callbacks are being passed the event loop, the watcher that
4254	received the event, and the actual event bitset.	4968	received the event, and the actual event bitset.
4255		4969
4256	=item callback invocation	4970	=item callback/watcher invocation
4257		4971
4258	The act of calling the callback associated with a watcher.	4972	The act of calling the callback associated with a watcher.
4259		4973
4260	=item event	4974	=item event
4261		4975
4262	A change of state of some external event, such as data now being available	4976	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	4977	for reading on a file descriptor, time having passed or simply not having
4264	any other events happening anymore.	4978	any other events happening anymore.
4265		4979
4266	In libev, events are represented as single bits (such as C<EV_READ> or	4980	In libev, events are represented as single bits (such as C<EV_READ> or
4267	C<EV_TIMEOUT>).	4981	C<EV_TIMER>).
4268		4982
4269	=item event library	4983	=item event library
4270		4984
4271	A software package implementing an event model and loop.	4985	A software package implementing an event model and loop.
4272		4986
…		…
4280	The model used to describe how an event loop handles and processes	4994	The model used to describe how an event loop handles and processes
4281	watchers and events.	4995	watchers and events.
4282		4996
4283	=item pending	4997	=item pending
4284		4998
4285	A watcher is pending as soon as the corresponding event has been detected,	4999	A watcher is pending as soon as the corresponding event has been
4286	and stops being pending as soon as the watcher will be invoked or its	5000	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		5001
4292	=item real time	5002	=item real time
4293		5003
4294	The physical time that is observed. It is apparently strictly monotonic :)	5004	The physical time that is observed. It is apparently strictly monotonic :)
4295		5005
…		…
4302	=item watcher	5012	=item watcher
4303		5013
4304	A data structure that describes interest in certain events. Watchers need	5014	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.	5015	to be started (attached to an event loop) before they can receive events.
4306		5016
4307	=item watcher invocation
4308
4309	The act of calling the callback associated with a watcher.
4310
4311	=back	5017	=back
4312		5018
4313	=head1 AUTHOR	5019	=head1 AUTHOR
4314		5020
4315	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson.	5021	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael
		5022	Magnusson and Emanuele Giaquinta.
4316		5023

Diff Legend

–	Removed lines
+	Added lines
<	Changed lines
>	Changed lines