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Revision 1.354 by root, Tue Jan 11 01:40:25 2011 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))
234		247
235	Sets the allocation function to use (the prototype is similar - the	248	Sets the allocation function to use (the prototype is similar - the
236	semantics are identical to the C<realloc> C89/SuS/POSIX function). It is	249	semantics are identical to the C<realloc> C89/SuS/POSIX function). It is
237	used to allocate and free memory (no surprises here). If it returns zero	250	used to allocate and free memory (no surprises here). If it returns zero
238	when memory needs to be allocated (C<size != 0>), the library might abort	251	when memory needs to be allocated (C<size != 0>), the library might abort
…		…
264	}	277	}
265		278
266	...	279	...
267	ev_set_allocator (persistent_realloc);	280	ev_set_allocator (persistent_realloc);
268		281
269	=item ev_set_syserr_cb (void (*cb)(const char *msg)); [NOT REENTRANT]	282	=item ev_set_syserr_cb (void (*cb)(const char *msg))
270		283
271	Set the callback function to call on a retryable system call error (such	284	Set the callback function to call on a retryable system call error (such
272	as failed select, poll, epoll_wait). The message is a printable string	285	as failed select, poll, epoll_wait). The message is a printable string
273	indicating the system call or subsystem causing the problem. If this	286	indicating the system call or subsystem causing the problem. If this
274	callback is set, then libev will expect it to remedy the situation, no	287	callback is set, then libev will expect it to remedy the situation, no
…		…
286	}	299	}
287		300
288	...	301	...
289	ev_set_syserr_cb (fatal_error);	302	ev_set_syserr_cb (fatal_error);
290		303
		304	=item ev_feed_signal (int signum)
		305
		306	This function can be used to "simulate" a signal receive. It is completely
		307	safe to call this function at any time, from any context, including signal
		308	handlers or random threads.
		309
		310	Its main use is to customise signal handling in your process, especially
		311	in the presence of threads. For example, you could block signals
		312	by default in all threads (and specifying C<EVFLAG_NOSIGMASK> when
		313	creating any loops), and in one thread, use C<sigwait> or any other
		314	mechanism to wait for signals, then "deliver" them to libev by calling
		315	C<ev_feed_signal>.
		316
291	=back	317	=back
292		318
293	=head1 FUNCTIONS CONTROLLING THE EVENT LOOP	319	=head1 FUNCTIONS CONTROLLING EVENT LOOPS
294		320
295	An event loop is described by a C<struct ev_loop *> (the C<struct>	321	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>	322	I<not> optional in this case unless libev 3 compatibility is disabled, as
297	I<function>).	323	libev 3 had an C<ev_loop> function colliding with the struct name).
298		324
299	The library knows two types of such loops, the I<default> loop, which	325	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	326	supports child process events, and dynamically created event loops which
301	not.	327	do not.
302		328
303	=over 4	329	=over 4
304		330
305	=item struct ev_loop *ev_default_loop (unsigned int flags)	331	=item struct ev_loop *ev_default_loop (unsigned int flags)
306		332
307	This will initialise the default event loop if it hasn't been initialised	333	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	334	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	335	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).	336	C<ev_loop_new>.
		337
		338	If the default loop is already initialised then this function simply
		339	returns it (and ignores the flags. If that is troubling you, check
		340	C<ev_backend ()> afterwards). Otherwise it will create it with the given
		341	flags, which should almost always be C<0>, unless the caller is also the
		342	one calling C<ev_run> or otherwise qualifies as "the main program".
311		343
312	If you don't know what event loop to use, use the one returned from this	344	If you don't know what event loop to use, use the one returned from this
313	function.	345	function (or via the C<EV_DEFAULT> macro).
314		346
315	Note that this function is I<not> thread-safe, so if you want to use it	347	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,	348	from multiple threads, you have to employ some kind of mutex (note also
317	as loops cannot be shared easily between threads anyway).	349	that this case is unlikely, as loops cannot be shared easily between
		350	threads anyway).
318		351
319	The default loop is the only loop that can handle C<ev_signal> and	352	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	353	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	354	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	355	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	356	C<SIGCHLD> signal handler I<after> calling C<ev_default_init>.
324	C<ev_default_init>.	357
		358	Example: This is the most typical usage.
		359
		360	if (!ev_default_loop (0))
		361	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
		362
		363	Example: Restrict libev to the select and poll backends, and do not allow
		364	environment settings to be taken into account:
		365
		366	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
		367
		368	=item struct ev_loop *ev_loop_new (unsigned int flags)
		369
		370	This will create and initialise a new event loop object. If the loop
		371	could not be initialised, returns false.
		372
		373	This function is thread-safe, and one common way to use libev with
		374	threads is indeed to create one loop per thread, and using the default
		375	loop in the "main" or "initial" thread.
325		376
326	The flags argument can be used to specify special behaviour or specific	377	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>).	378	backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>).
328		379
329	The following flags are supported:	380	The following flags are supported:
…		…
344	useful to try out specific backends to test their performance, or to work	395	useful to try out specific backends to test their performance, or to work
345	around bugs.	396	around bugs.
346		397
347	=item C<EVFLAG_FORKCHECK>	398	=item C<EVFLAG_FORKCHECK>
348		399
349	Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after	400	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	401	make libev check for a fork in each iteration by enabling this flag.
351	enabling this flag.
352		402
353	This works by calling C<getpid ()> on every iteration of the loop,	403	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	404	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	405	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	406	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence
…		…
362	flag.	412	flag.
363		413
364	This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS>	414	This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS>
365	environment variable.	415	environment variable.
366		416
		417	=item C<EVFLAG_NOINOTIFY>
		418
		419	When this flag is specified, then libev will not attempt to use the
		420	I<inotify> API for its C<ev_stat> watchers. Apart from debugging and
		421	testing, this flag can be useful to conserve inotify file descriptors, as
		422	otherwise each loop using C<ev_stat> watchers consumes one inotify handle.
		423
		424	=item C<EVFLAG_SIGNALFD>
		425
		426	When this flag is specified, then libev will attempt to use the
		427	I<signalfd> API for its C<ev_signal> (and C<ev_child>) watchers. This API
		428	delivers signals synchronously, which makes it both faster and might make
		429	it possible to get the queued signal data. It can also simplify signal
		430	handling with threads, as long as you properly block signals in your
		431	threads that are not interested in handling them.
		432
		433	Signalfd will not be used by default as this changes your signal mask, and
		434	there are a lot of shoddy libraries and programs (glib's threadpool for
		435	example) that can't properly initialise their signal masks.
		436
		437	=item C<EVFLAG_NOSIGMASK>
		438
		439	When this flag is specified, then libev will avoid to modify the signal
		440	mask. Specifically, this means you ahve to make sure signals are unblocked
		441	when you want to receive them.
		442
		443	This behaviour is useful when you want to do your own signal handling, or
		444	want to handle signals only in specific threads and want to avoid libev
		445	unblocking the signals.
		446
		447	This flag's behaviour will become the default in future versions of libev.
		448
367	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	449	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
368		450
369	This is your standard select(2) backend. Not I<completely> standard, as	451	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,	452	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	453	but if that fails, expect a fairly low limit on the number of fds when
…		…
395	This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and	477	This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and
396	C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>.	478	C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>.
397		479
398	=item C<EVBACKEND_EPOLL> (value 4, Linux)	480	=item C<EVBACKEND_EPOLL> (value 4, Linux)
399		481
		482	Use the linux-specific epoll(7) interface (for both pre- and post-2.6.9
		483	kernels).
		484
400	For few fds, this backend is a bit little slower than poll and select,	485	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	486	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),	487	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).	488	epoll scales either O(1) or O(active_fds).
404		489
405	The epoll mechanism deserves honorable mention as the most misdesigned	490	The epoll mechanism deserves honorable mention as the most misdesigned
406	of the more advanced event mechanisms: mere annoyances include silently	491	of the more advanced event mechanisms: mere annoyances include silently
407	dropping file descriptors, requiring a system call per change per file	492	dropping file descriptors, requiring a system call per change per file
408	descriptor (and unnecessary guessing of parameters), problems with dup and	493	descriptor (and unnecessary guessing of parameters), problems with dup,
		494	returning before the timeout value, resulting in additional iterations
		495	(and only giving 5ms accuracy while select on the same platform gives
409	so on. The biggest issue is fork races, however - if a program forks then	496	0.1ms) and so on. The biggest issue is fork races, however - if a program
410	I<both> parent and child process have to recreate the epoll set, which can	497	forks then I<both> parent and child process have to recreate the epoll
411	take considerable time (one syscall per file descriptor) and is of course	498	set, which can take considerable time (one syscall per file descriptor)
412	hard to detect.	499	and is of course hard to detect.
413		500
414	Epoll is also notoriously buggy - embedding epoll fds I<should> work, but	501	Epoll is also notoriously buggy - embedding epoll fds I<should> work, but
415	of course I<doesn't>, and epoll just loves to report events for totally	502	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	503	I<different> file descriptors (even already closed ones, so one cannot
417	even remove them from the set) than registered in the set (especially	504	even remove them from the set) than registered in the set (especially
418	on SMP systems). Libev tries to counter these spurious notifications by	505	on SMP systems). Libev tries to counter these spurious notifications by
419	employing an additional generation counter and comparing that against the	506	employing an additional generation counter and comparing that against the
420	events to filter out spurious ones, recreating the set when required.	507	events to filter out spurious ones, recreating the set when required. Last
		508	not least, it also refuses to work with some file descriptors which work
		509	perfectly fine with C<select> (files, many character devices...).
		510
		511	Epoll is truly the train wreck analog among event poll mechanisms,
		512	a frankenpoll, cobbled together in a hurry, no thought to design or
		513	interaction with others.
421		514
422	While stopping, setting and starting an I/O watcher in the same iteration	515	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	516	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	517	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	518	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed
…		…
491	=item C<EVBACKEND_PORT> (value 32, Solaris 10)	584	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
492		585
493	This uses the Solaris 10 event port mechanism. As with everything on Solaris,	586	This uses the Solaris 10 event port mechanism. As with everything on Solaris,
494	it's really slow, but it still scales very well (O(active_fds)).	587	it's really slow, but it still scales very well (O(active_fds)).
495		588
496	Please note that Solaris event ports can deliver a lot of spurious
497	notifications, so you need to use non-blocking I/O or other means to avoid
498	blocking when no data (or space) is available.
499
500	While this backend scales well, it requires one system call per active	589	While this backend scales well, it requires one system call per active
501	file descriptor per loop iteration. For small and medium numbers of file	590	file descriptor per loop iteration. For small and medium numbers of file
502	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend	591	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend
503	might perform better.	592	might perform better.
504		593
505	On the positive side, with the exception of the spurious readiness	594	On the positive side, this backend actually performed fully to
506	notifications, this backend actually performed fully to specification
507	in all tests and is fully embeddable, which is a rare feat among the	595	specification in all tests and is fully embeddable, which is a rare feat
508	OS-specific backends (I vastly prefer correctness over speed hacks).	596	among the OS-specific backends (I vastly prefer correctness over speed
		597	hacks).
		598
		599	On the negative side, the interface is I<bizarre> - so bizarre that
		600	even sun itself gets it wrong in their code examples: The event polling
		601	function sometimes returning events to the caller even though an error
		602	occurred, but with no indication whether it has done so or not (yes, it's
		603	even documented that way) - deadly for edge-triggered interfaces where
		604	you absolutely have to know whether an event occurred or not because you
		605	have to re-arm the watcher.
		606
		607	Fortunately libev seems to be able to work around these idiocies.
509		608
510	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as	609	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as
511	C<EVBACKEND_POLL>.	610	C<EVBACKEND_POLL>.
512		611
513	=item C<EVBACKEND_ALL>	612	=item C<EVBACKEND_ALL>
514		613
515	Try all backends (even potentially broken ones that wouldn't be tried	614	Try all backends (even potentially broken ones that wouldn't be tried
516	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as	615	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as
517	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.	616	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.
518		617
519	It is definitely not recommended to use this flag.	618	It is definitely not recommended to use this flag, use whatever
		619	C<ev_recommended_backends ()> returns, or simply do not specify a backend
		620	at all.
		621
		622	=item C<EVBACKEND_MASK>
		623
		624	Not a backend at all, but a mask to select all backend bits from a
		625	C<flags> value, in case you want to mask out any backends from a flags
		626	value (e.g. when modifying the C<LIBEV_FLAGS> environment variable).
520		627
521	=back	628	=back
522		629
523	If one or more of these are or'ed into the flags value, then only these	630	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	631	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.	632	here). If none are specified, all backends in C<ev_recommended_backends
526		633	()> 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		634
555	Example: Try to create a event loop that uses epoll and nothing else.	635	Example: Try to create a event loop that uses epoll and nothing else.
556		636
557	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	637	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
558	if (!epoller)	638	if (!epoller)
559	fatal ("no epoll found here, maybe it hides under your chair");	639	fatal ("no epoll found here, maybe it hides under your chair");
560		640
		641	Example: Use whatever libev has to offer, but make sure that kqueue is
		642	used if available.
		643
		644	struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE);
		645
561	=item ev_default_destroy ()	646	=item ev_loop_destroy (loop)
562		647
563	Destroys the default loop again (frees all memory and kernel state	648	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	649	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	650	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>	651	responsibility to either stop all watchers cleanly yourself I<before>
567	calling this function, or cope with the fact afterwards (which is usually	652	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	653	the easiest thing, you can just ignore the watchers and/or C<free ()> them
…		…
570		655
571	Note that certain global state, such as signal state (and installed signal	656	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	657	handlers), will not be freed by this function, and related watchers (such
573	as signal and child watchers) would need to be stopped manually.	658	as signal and child watchers) would need to be stopped manually.
574		659
575	In general it is not advisable to call this function except in the	660	This function is normally used on loop objects allocated by
576	rare occasion where you really need to free e.g. the signal handling	661	C<ev_loop_new>, but it can also be used on the default loop returned by
		662	C<ev_default_loop>, in which case it is not thread-safe.
		663
		664	Note that it is not advisable to call this function on the default loop
		665	except in the rare occasion where you really need to free its resources.
577	pipe fds. If you need dynamically allocated loops it is better to use	666	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>).	667	and C<ev_loop_destroy>.
579		668
580	=item ev_loop_destroy (loop)	669	=item ev_loop_fork (loop)
581		670
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	671	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	672	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	673	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	674	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	675	child before resuming or calling C<ev_run>.
592	functions, and it will only take effect at the next C<ev_loop> iteration.	676
		677	Again, you I<have> to call it on I<any> loop that you want to re-use after
		678	a fork, I<even if you do not plan to use the loop in the parent>. This is
		679	because some kernel interfaces *cough* I<kqueue> *cough* do funny things
		680	during fork.
593		681
594	On the other hand, you only need to call this function in the child	682	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	683	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.	684	you just fork+exec or create a new loop in the child, you don't have to
		685	call it at all (in fact, C<epoll> is so badly broken that it makes a
		686	difference, but libev will usually detect this case on its own and do a
		687	costly reset of the backend).
597		688
598	The function itself is quite fast and it's usually not a problem to call	689	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	690	it just in case after a fork.
600	quite nicely into a call to C<pthread_atfork>:
601		691
		692	Example: Automate calling C<ev_loop_fork> on the default loop when
		693	using pthreads.
		694
		695	static void
		696	post_fork_child (void)
		697	{
		698	ev_loop_fork (EV_DEFAULT);
		699	}
		700
		701	...
602	pthread_atfork (0, 0, ev_default_fork);	702	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		703
611	=item int ev_is_default_loop (loop)	704	=item int ev_is_default_loop (loop)
612		705
613	Returns true when the given loop is, in fact, the default loop, and false	706	Returns true when the given loop is, in fact, the default loop, and false
614	otherwise.	707	otherwise.
615		708
616	=item unsigned int ev_loop_count (loop)	709	=item unsigned int ev_iteration (loop)
617		710
618	Returns the count of loop iterations for the loop, which is identical to	711	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	712	to the number of times libev did poll for new events. It starts at C<0>
620	happily wraps around with enough iterations.	713	and happily wraps around with enough iterations.
621		714
622	This value can sometimes be useful as a generation counter of sorts (it	715	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	716	"ticks" the number of loop iterations), as it roughly corresponds with
624	C<ev_prepare> and C<ev_check> calls.	717	C<ev_prepare> and C<ev_check> calls - and is incremented between the
		718	prepare and check phases.
625		719
626	=item unsigned int ev_loop_depth (loop)	720	=item unsigned int ev_depth (loop)
627		721
628	Returns the number of times C<ev_loop> was entered minus the number of	722	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.	723	times C<ev_run> was exited normally, in other words, the recursion depth.
630		724
631	Outside C<ev_loop>, this number is zero. In a callback, this number is	725	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),	726	C<1>, unless C<ev_run> was invoked recursively (or from another thread),
633	in which case it is higher.	727	in which case it is higher.
634		728
635	Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread	729	Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread,
636	etc.), doesn't count as exit.	730	throwing an exception etc.), doesn't count as "exit" - consider this
		731	as a hint to avoid such ungentleman-like behaviour unless it's really
		732	convenient, in which case it is fully supported.
637		733
638	=item unsigned int ev_backend (loop)	734	=item unsigned int ev_backend (loop)
639		735
640	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	736	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
641	use.	737	use.
…		…
650		746
651	=item ev_now_update (loop)	747	=item ev_now_update (loop)
652		748
653	Establishes the current time by querying the kernel, updating the time	749	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	750	returned by C<ev_now ()> in the progress. This is a costly operation and
655	is usually done automatically within C<ev_loop ()>.	751	is usually done automatically within C<ev_run ()>.
656		752
657	This function is rarely useful, but when some event callback runs for a	753	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	754	very long time without entering the event loop, updating libev's idea of
659	the current time is a good idea.	755	the current time is a good idea.
660		756
…		…
662		758
663	=item ev_suspend (loop)	759	=item ev_suspend (loop)
664		760
665	=item ev_resume (loop)	761	=item ev_resume (loop)
666		762
667	These two functions suspend and resume a loop, for use when the loop is	763	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.	764	loop is not used for a while and timeouts should not be processed.
669		765
670	A typical use case would be an interactive program such as a game: When	766	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	767	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	768	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>	769	the program was suspended. This can be achieved by calling C<ev_suspend>
…		…
675	C<ev_resume> directly afterwards to resume timer processing.	771	C<ev_resume> directly afterwards to resume timer processing.
676		772
677	Effectively, all C<ev_timer> watchers will be delayed by the time spend	773	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	774	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	775	will be rescheduled (that is, they will lose any events that would have
680	occured while suspended).	776	occurred while suspended).
681		777
682	After calling C<ev_suspend> you B<must not> call I<any> function on the	778	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>	779	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>.	780	without a previous call to C<ev_suspend>.
685		781
686	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the	782	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the
687	event loop time (see C<ev_now_update>).	783	event loop time (see C<ev_now_update>).
688		784
689	=item ev_loop (loop, int flags)	785	=item ev_run (loop, int flags)
690		786
691	Finally, this is it, the event handler. This function usually is called	787	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	788	after you have initialised all your watchers and you want to start
693	events.	789	handling events. It will ask the operating system for any new events, call
		790	the watcher callbacks, an then repeat the whole process indefinitely: This
		791	is why event loops are called I<loops>.
694		792
695	If the flags argument is specified as C<0>, it will not return until	793	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.	794	until either no event watchers are active anymore or C<ev_break> was
		795	called.
697		796
698	Please note that an explicit C<ev_unloop> is usually better than	797	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	798	relying on all watchers to be stopped when deciding when a program has
700	finished (especially in interactive programs), but having a program	799	finished (especially in interactive programs), but having a program
701	that automatically loops as long as it has to and no longer by virtue	800	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	801	of relying on its watchers stopping correctly, that is truly a thing of
703	beauty.	802	beauty.
704		803
		804	This function is also I<mostly> exception-safe - you can break out of
		805	a C<ev_run> call by calling C<longjmp> in a callback, throwing a C++
		806	exception and so on. This does not decrement the C<ev_depth> value, nor
		807	will it clear any outstanding C<EVBREAK_ONE> breaks.
		808
705	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle	809	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	810	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	811	block your process in case there are no events and will return after one
708	the loop.	812	iteration of the loop. This is sometimes useful to poll and handle new
		813	events while doing lengthy calculations, to keep the program responsive.
709		814
710	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if	815	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	816	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	817	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	818	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	819	user-registered callback will be called), and will return after one
715	iteration of the loop.	820	iteration of the loop.
716		821
717	This is useful if you are waiting for some external event in conjunction	822	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	823	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	824	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.	825	usually a better approach for this kind of thing.
721		826
722	Here are the gory details of what C<ev_loop> does:	827	Here are the gory details of what C<ev_run> does:
723		828
		829	- Increment loop depth.
		830	- Reset the ev_break status.
724	- Before the first iteration, call any pending watchers.	831	- Before the first iteration, call any pending watchers.
		832	LOOP:
725	* If EVFLAG_FORKCHECK was used, check for a fork.	833	- If EVFLAG_FORKCHECK was used, check for a fork.
726	- If a fork was detected (by any means), queue and call all fork watchers.	834	- If a fork was detected (by any means), queue and call all fork watchers.
727	- Queue and call all prepare watchers.	835	- Queue and call all prepare watchers.
		836	- If ev_break was called, goto FINISH.
728	- If we have been forked, detach and recreate the kernel state	837	- If we have been forked, detach and recreate the kernel state
729	as to not disturb the other process.	838	as to not disturb the other process.
730	- Update the kernel state with all outstanding changes.	839	- Update the kernel state with all outstanding changes.
731	- Update the "event loop time" (ev_now ()).	840	- Update the "event loop time" (ev_now ()).
732	- Calculate for how long to sleep or block, if at all	841	- Calculate for how long to sleep or block, if at all
733	(active idle watchers, EVLOOP_NONBLOCK or not having	842	(active idle watchers, EVRUN_NOWAIT or not having
734	any active watchers at all will result in not sleeping).	843	any active watchers at all will result in not sleeping).
735	- Sleep if the I/O and timer collect interval say so.	844	- Sleep if the I/O and timer collect interval say so.
		845	- Increment loop iteration counter.
736	- Block the process, waiting for any events.	846	- Block the process, waiting for any events.
737	- Queue all outstanding I/O (fd) events.	847	- Queue all outstanding I/O (fd) events.
738	- Update the "event loop time" (ev_now ()), and do time jump adjustments.	848	- Update the "event loop time" (ev_now ()), and do time jump adjustments.
739	- Queue all expired timers.	849	- Queue all expired timers.
740	- Queue all expired periodics.	850	- Queue all expired periodics.
741	- Unless any events are pending now, queue all idle watchers.	851	- Queue all idle watchers with priority higher than that of pending events.
742	- Queue all check watchers.	852	- Queue all check watchers.
743	- Call all queued watchers in reverse order (i.e. check watchers first).	853	- 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	854	Signals and child watchers are implemented as I/O watchers, and will
745	be handled here by queueing them when their watcher gets executed.	855	be handled here by queueing them when their watcher gets executed.
746	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	856	- If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT
747	were used, or there are no active watchers, return, otherwise	857	were used, or there are no active watchers, goto FINISH, otherwise
748	continue with step *.	858	continue with step LOOP.
		859	FINISH:
		860	- Reset the ev_break status iff it was EVBREAK_ONE.
		861	- Decrement the loop depth.
		862	- Return.
749		863
750	Example: Queue some jobs and then loop until no events are outstanding	864	Example: Queue some jobs and then loop until no events are outstanding
751	anymore.	865	anymore.
752		866
753	... queue jobs here, make sure they register event watchers as long	867	... 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..)	868	... as they still have work to do (even an idle watcher will do..)
755	ev_loop (my_loop, 0);	869	ev_run (my_loop, 0);
756	... jobs done or somebody called unloop. yeah!	870	... jobs done or somebody called unloop. yeah!
757		871
758	=item ev_unloop (loop, how)	872	=item ev_break (loop, how)
759		873
760	Can be used to make a call to C<ev_loop> return early (but only after it	874	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	875	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	876	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.	877	C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return.
764		878
765	This "unloop state" will be cleared when entering C<ev_loop> again.	879	This "break state" will be cleared on the next call to C<ev_run>.
766		880
767	It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls.	881	It is safe to call C<ev_break> from outside any C<ev_run> calls, too, in
		882	which case it will have no effect.
768		883
769	=item ev_ref (loop)	884	=item ev_ref (loop)
770		885
771	=item ev_unref (loop)	886	=item ev_unref (loop)
772		887
773	Ref/unref can be used to add or remove a reference count on the event	888	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	889	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.	890	count is nonzero, C<ev_run> will not return on its own.
776		891
777	If you have a watcher you never unregister that should not keep C<ev_loop>	892	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	893	unregister, but that nevertheless should not keep C<ev_run> from
		894	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>
779	stopping it.	895	before stopping it.
780		896
781	As an example, libev itself uses this for its internal signal pipe: It	897	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	898	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	899	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	900	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	901	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	902	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	903	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>	904	(e.g. non-repeating timers) in which case you have to C<ev_ref>
789	in the callback).	905	in the callback).
790		906
791	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	907	Example: Create a signal watcher, but keep it from keeping C<ev_run>
792	running when nothing else is active.	908	running when nothing else is active.
793		909
794	ev_signal exitsig;	910	ev_signal exitsig;
795	ev_signal_init (&exitsig, sig_cb, SIGINT);	911	ev_signal_init (&exitsig, sig_cb, SIGINT);
796	ev_signal_start (loop, &exitsig);	912	ev_signal_start (loop, &exitsig);
797	evf_unref (loop);	913	ev_unref (loop);
798		914
799	Example: For some weird reason, unregister the above signal handler again.	915	Example: For some weird reason, unregister the above signal handler again.
800		916
801	ev_ref (loop);	917	ev_ref (loop);
802	ev_signal_stop (loop, &exitsig);	918	ev_signal_stop (loop, &exitsig);
…		…
841	usually doesn't make much sense to set it to a lower value than C<0.01>,	957	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	958	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	959	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	960	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,	961	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).	962	then you can't do more than 100 transactions per second).
847		963
848	Setting the I<timeout collect interval> can improve the opportunity for	964	Setting the I<timeout collect interval> can improve the opportunity for
849	saving power, as the program will "bundle" timer callback invocations that	965	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	966	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	967	times the process sleeps and wakes up again. Another useful technique to
…		…
859	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);	975	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);
860		976
861	=item ev_invoke_pending (loop)	977	=item ev_invoke_pending (loop)
862		978
863	This call will simply invoke all pending watchers while resetting their	979	This call will simply invoke all pending watchers while resetting their
864	pending state. Normally, C<ev_loop> does this automatically when required,	980	pending state. Normally, C<ev_run> does this automatically when required,
865	but when overriding the invoke callback this call comes handy.	981	but when overriding the invoke callback this call comes handy. This
		982	function can be invoked from a watcher - this can be useful for example
		983	when you want to do some lengthy calculation and want to pass further
		984	event handling to another thread (you still have to make sure only one
		985	thread executes within C<ev_invoke_pending> or C<ev_run> of course).
		986
		987	=item int ev_pending_count (loop)
		988
		989	Returns the number of pending watchers - zero indicates that no watchers
		990	are pending.
866		991
867	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))	992	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))
868		993
869	This overrides the invoke pending functionality of the loop: Instead of	994	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	995	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	996	this callback instead. This is useful, for example, when you want to
872	invoke the actual watchers inside another context (another thread etc.).	997	invoke the actual watchers inside another context (another thread etc.).
873		998
874	If you want to reset the callback, use C<ev_invoke_pending> as new	999	If you want to reset the callback, use C<ev_invoke_pending> as new
875	callback.	1000	callback.
…		…
878		1003
879	Sometimes you want to share the same loop between multiple threads. This	1004	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	1005	can be done relatively simply by putting mutex_lock/unlock calls around
881	each call to a libev function.	1006	each call to a libev function.
882		1007
883	However, C<ev_loop> can run an indefinite time, so it is not feasible to	1008	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	1009	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>	1010	loop via C<ev_break> and C<av_async_send>, another way is to set these
886	and I<acquire> callbacks on the loop.	1011	I<release> and I<acquire> callbacks on the loop.
887		1012
888	When set, then C<release> will be called just before the thread is	1013	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	1014	suspended waiting for new events, and C<acquire> is called just
890	afterwards.	1015	afterwards.
891		1016
892	Ideally, C<release> will just call your mutex_unlock function, and	1017	Ideally, C<release> will just call your mutex_unlock function, and
893	C<acquire> will just call the mutex_lock function again.	1018	C<acquire> will just call the mutex_lock function again.
894		1019
		1020	While event loop modifications are allowed between invocations of
		1021	C<release> and C<acquire> (that's their only purpose after all), no
		1022	modifications done will affect the event loop, i.e. adding watchers will
		1023	have no effect on the set of file descriptors being watched, or the time
		1024	waited. Use an C<ev_async> watcher to wake up C<ev_run> when you want it
		1025	to take note of any changes you made.
		1026
		1027	In theory, threads executing C<ev_run> will be async-cancel safe between
		1028	invocations of C<release> and C<acquire>.
		1029
		1030	See also the locking example in the C<THREADS> section later in this
		1031	document.
		1032
895	=item ev_set_userdata (loop, void *data)	1033	=item ev_set_userdata (loop, void *data)
896		1034
897	=item ev_userdata (loop)	1035	=item void *ev_userdata (loop)
898		1036
899	Set and retrieve a single C<void *> associated with a loop. When	1037	Set and retrieve a single C<void *> associated with a loop. When
900	C<ev_set_userdata> has never been called, then C<ev_userdata> returns	1038	C<ev_set_userdata> has never been called, then C<ev_userdata> returns
901	C<0.>	1039	C<0>.
902		1040
903	These two functions can be used to associate arbitrary data with a loop,	1041	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	1042	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	1043	C<acquire> callbacks described above, but of course can be (ab-)used for
906	any other purpose as well.	1044	any other purpose as well.
907		1045
908	=item ev_loop_verify (loop)	1046	=item ev_verify (loop)
909		1047
910	This function only does something when C<EV_VERIFY> support has been	1048	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	1049	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	1050	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	1051	is found to be inconsistent, it will print an error message to standard
…		…
924		1062
925	In the following description, uppercase C<TYPE> in names stands for the	1063	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	1064	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.	1065	watchers and C<ev_io_start> for I/O watchers.
928		1066
929	A watcher is a structure that you create and register to record your	1067	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	1068	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:	1069	to wait for STDIN to become readable, you would create an C<ev_io> watcher
		1070	for that:
932		1071
933	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)	1072	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)
934	{	1073	{
935	ev_io_stop (w);	1074	ev_io_stop (w);
936	ev_unloop (loop, EVUNLOOP_ALL);	1075	ev_break (loop, EVBREAK_ALL);
937	}	1076	}
938		1077
939	struct ev_loop *loop = ev_default_loop (0);	1078	struct ev_loop *loop = ev_default_loop (0);
940		1079
941	ev_io stdin_watcher;	1080	ev_io stdin_watcher;
942		1081
943	ev_init (&stdin_watcher, my_cb);	1082	ev_init (&stdin_watcher, my_cb);
944	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	1083	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
945	ev_io_start (loop, &stdin_watcher);	1084	ev_io_start (loop, &stdin_watcher);
946		1085
947	ev_loop (loop, 0);	1086	ev_run (loop, 0);
948		1087
949	As you can see, you are responsible for allocating the memory for your	1088	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	1089	watcher structures (and it is I<usually> a bad idea to do this on the
951	stack).	1090	stack).
952		1091
953	Each watcher has an associated watcher structure (called C<struct ev_TYPE>	1092	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).	1093	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).
955		1094
956	Each watcher structure must be initialised by a call to C<ev_init	1095	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	1096	*, 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	1097	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	1098	time the event loop detects that the file descriptor given is readable
960	is readable and/or writable).	1099	and/or writable).
961		1100
962	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>	1101	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	1102	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<<	1103	is also a macro to combine initialisation and setting in one call: C<<
965	ev_TYPE_init (watcher *, callback, ...) >>.	1104	ev_TYPE_init (watcher *, callback, ...) >>.
…		…
988	=item C<EV_WRITE>	1127	=item C<EV_WRITE>
989		1128
990	The file descriptor in the C<ev_io> watcher has become readable and/or	1129	The file descriptor in the C<ev_io> watcher has become readable and/or
991	writable.	1130	writable.
992		1131
993	=item C<EV_TIMEOUT>	1132	=item C<EV_TIMER>
994		1133
995	The C<ev_timer> watcher has timed out.	1134	The C<ev_timer> watcher has timed out.
996		1135
997	=item C<EV_PERIODIC>	1136	=item C<EV_PERIODIC>
998		1137
…		…
1016		1155
1017	=item C<EV_PREPARE>	1156	=item C<EV_PREPARE>
1018		1157
1019	=item C<EV_CHECK>	1158	=item C<EV_CHECK>
1020		1159
1021	All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts	1160	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	1161	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	1162	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	1163	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	1164	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	1165	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
1027	C<ev_loop> from blocking).	1166	C<ev_run> from blocking).
1028		1167
1029	=item C<EV_EMBED>	1168	=item C<EV_EMBED>
1030		1169
1031	The embedded event loop specified in the C<ev_embed> watcher needs attention.	1170	The embedded event loop specified in the C<ev_embed> watcher needs attention.
1032		1171
1033	=item C<EV_FORK>	1172	=item C<EV_FORK>
1034		1173
1035	The event loop has been resumed in the child process after fork (see	1174	The event loop has been resumed in the child process after fork (see
1036	C<ev_fork>).	1175	C<ev_fork>).
		1176
		1177	=item C<EV_CLEANUP>
		1178
		1179	The event loop is about to be destroyed (see C<ev_cleanup>).
1037		1180
1038	=item C<EV_ASYNC>	1181	=item C<EV_ASYNC>
1039		1182
1040	The given async watcher has been asynchronously notified (see C<ev_async>).	1183	The given async watcher has been asynchronously notified (see C<ev_async>).
1041		1184
…		…
1088		1231
1089	ev_io w;	1232	ev_io w;
1090	ev_init (&w, my_cb);	1233	ev_init (&w, my_cb);
1091	ev_io_set (&w, STDIN_FILENO, EV_READ);	1234	ev_io_set (&w, STDIN_FILENO, EV_READ);
1092		1235
1093	=item C<ev_TYPE_set> (ev_TYPE *, [args])	1236	=item C<ev_TYPE_set> (ev_TYPE *watcher, [args])
1094		1237
1095	This macro initialises the type-specific parts of a watcher. You need to	1238	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	1239	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	1240	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	1241	macro on a watcher that is active (it can be pending, however, which is a
…		…
1111		1254
1112	Example: Initialise and set an C<ev_io> watcher in one step.	1255	Example: Initialise and set an C<ev_io> watcher in one step.
1113		1256
1114	ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ);	1257	ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ);
1115		1258
1116	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)	1259	=item C<ev_TYPE_start> (loop, ev_TYPE *watcher)
1117		1260
1118	Starts (activates) the given watcher. Only active watchers will receive	1261	Starts (activates) the given watcher. Only active watchers will receive
1119	events. If the watcher is already active nothing will happen.	1262	events. If the watcher is already active nothing will happen.
1120		1263
1121	Example: Start the C<ev_io> watcher that is being abused as example in this	1264	Example: Start the C<ev_io> watcher that is being abused as example in this
1122	whole section.	1265	whole section.
1123		1266
1124	ev_io_start (EV_DEFAULT_UC, &w);	1267	ev_io_start (EV_DEFAULT_UC, &w);
1125		1268
1126	=item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher)	1269	=item C<ev_TYPE_stop> (loop, ev_TYPE *watcher)
1127		1270
1128	Stops the given watcher if active, and clears the pending status (whether	1271	Stops the given watcher if active, and clears the pending status (whether
1129	the watcher was active or not).	1272	the watcher was active or not).
1130		1273
1131	It is possible that stopped watchers are pending - for example,	1274	It is possible that stopped watchers are pending - for example,
…		…
1156	=item ev_cb_set (ev_TYPE *watcher, callback)	1299	=item ev_cb_set (ev_TYPE *watcher, callback)
1157		1300
1158	Change the callback. You can change the callback at virtually any time	1301	Change the callback. You can change the callback at virtually any time
1159	(modulo threads).	1302	(modulo threads).
1160		1303
1161	=item ev_set_priority (ev_TYPE *watcher, priority)	1304	=item ev_set_priority (ev_TYPE *watcher, int priority)
1162		1305
1163	=item int ev_priority (ev_TYPE *watcher)	1306	=item int ev_priority (ev_TYPE *watcher)
1164		1307
1165	Set and query the priority of the watcher. The priority is a small	1308	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>	1309	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>
…		…
1198	watcher isn't pending it does nothing and returns C<0>.	1341	watcher isn't pending it does nothing and returns C<0>.
1199		1342
1200	Sometimes it can be useful to "poll" a watcher instead of waiting for its	1343	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.	1344	callback to be invoked, which can be accomplished with this function.
1202		1345
		1346	=item ev_feed_event (loop, ev_TYPE *watcher, int revents)
		1347
		1348	Feeds the given event set into the event loop, as if the specified event
		1349	had happened for the specified watcher (which must be a pointer to an
		1350	initialised but not necessarily started event watcher). Obviously you must
		1351	not free the watcher as long as it has pending events.
		1352
		1353	Stopping the watcher, letting libev invoke it, or calling
		1354	C<ev_clear_pending> will clear the pending event, even if the watcher was
		1355	not started in the first place.
		1356
		1357	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related
		1358	functions that do not need a watcher.
		1359
1203	=back	1360	=back
1204
1205		1361
1206	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	1362	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
1207		1363
1208	Each watcher has, by default, a member C<void *data> that you can change	1364	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	1365	and read at any time: libev will completely ignore it. This can be used
…		…
1265	t2_cb (EV_P_ ev_timer *w, int revents)	1421	t2_cb (EV_P_ ev_timer *w, int revents)
1266	{	1422	{
1267	struct my_biggy big = (struct my_biggy *)	1423	struct my_biggy big = (struct my_biggy *)
1268	(((char *)w) - offsetof (struct my_biggy, t2));	1424	(((char *)w) - offsetof (struct my_biggy, t2));
1269	}	1425	}
		1426
		1427	=head2 WATCHER STATES
		1428
		1429	There are various watcher states mentioned throughout this manual -
		1430	active, pending and so on. In this section these states and the rules to
		1431	transition between them will be described in more detail - and while these
		1432	rules might look complicated, they usually do "the right thing".
		1433
		1434	=over 4
		1435
		1436	=item initialiased
		1437
		1438	Before a watcher can be registered with the event looop it has to be
		1439	initialised. This can be done with a call to C<ev_TYPE_init>, or calls to
		1440	C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function.
		1441
		1442	In this state it is simply some block of memory that is suitable for use
		1443	in an event loop. It can be moved around, freed, reused etc. at will.
		1444
		1445	=item started/running/active
		1446
		1447	Once a watcher has been started with a call to C<ev_TYPE_start> it becomes
		1448	property of the event loop, and is actively waiting for events. While in
		1449	this state it cannot be accessed (except in a few documented ways), moved,
		1450	freed or anything else - the only legal thing is to keep a pointer to it,
		1451	and call libev functions on it that are documented to work on active watchers.
		1452
		1453	=item pending
		1454
		1455	If a watcher is active and libev determines that an event it is interested
		1456	in has occurred (such as a timer expiring), it will become pending. It will
		1457	stay in this pending state until either it is stopped or its callback is
		1458	about to be invoked, so it is not normally pending inside the watcher
		1459	callback.
		1460
		1461	The watcher might or might not be active while it is pending (for example,
		1462	an expired non-repeating timer can be pending but no longer active). If it
		1463	is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>),
		1464	but it is still property of the event loop at this time, so cannot be
		1465	moved, freed or reused. And if it is active the rules described in the
		1466	previous item still apply.
		1467
		1468	It is also possible to feed an event on a watcher that is not active (e.g.
		1469	via C<ev_feed_event>), in which case it becomes pending without being
		1470	active.
		1471
		1472	=item stopped
		1473
		1474	A watcher can be stopped implicitly by libev (in which case it might still
		1475	be pending), or explicitly by calling its C<ev_TYPE_stop> function. The
		1476	latter will clear any pending state the watcher might be in, regardless
		1477	of whether it was active or not, so stopping a watcher explicitly before
		1478	freeing it is often a good idea.
		1479
		1480	While stopped (and not pending) the watcher is essentially in the
		1481	initialised state, that is it can be reused, moved, modified in any way
		1482	you wish.
		1483
		1484	=back
1270		1485
1271	=head2 WATCHER PRIORITY MODELS	1486	=head2 WATCHER PRIORITY MODELS
1272		1487
1273	Many event loops support I<watcher priorities>, which are usually small	1488	Many event loops support I<watcher priorities>, which are usually small
1274	integers that influence the ordering of event callback invocation	1489	integers that influence the ordering of event callback invocation
…		…
1317		1532
1318	For example, to emulate how many other event libraries handle priorities,	1533	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	1534	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	1535	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	1536	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	1537	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	1538	the lock-out case is known to be rare (which in turn is rare :), this is
1324	workable.	1539	workable.
1325		1540
1326	Usually, however, the lock-out model implemented that way will perform	1541	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,	1542	miserably under the type of load it was designed to handle. In that case,
…		…
1341	{	1556	{
1342	// stop the I/O watcher, we received the event, but	1557	// stop the I/O watcher, we received the event, but
1343	// are not yet ready to handle it.	1558	// are not yet ready to handle it.
1344	ev_io_stop (EV_A_ w);	1559	ev_io_stop (EV_A_ w);
1345		1560
1346	// start the idle watcher to ahndle the actual event.	1561	// start the idle watcher to handle the actual event.
1347	// it will not be executed as long as other watchers	1562	// it will not be executed as long as other watchers
1348	// with the default priority are receiving events.	1563	// with the default priority are receiving events.
1349	ev_idle_start (EV_A_ &idle);	1564	ev_idle_start (EV_A_ &idle);
1350	}	1565	}
1351		1566
…		…
1401	In general you can register as many read and/or write event watchers per	1616	In general you can register as many read and/or write event watchers per
1402	fd as you want (as long as you don't confuse yourself). Setting all file	1617	fd as you want (as long as you don't confuse yourself). Setting all file
1403	descriptors to non-blocking mode is also usually a good idea (but not	1618	descriptors to non-blocking mode is also usually a good idea (but not
1404	required if you know what you are doing).	1619	required if you know what you are doing).
1405		1620
1406	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
1408	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file
1409	descriptors for which non-blocking operation makes no sense (such as
1410	files) - libev doesn't guarentee any specific behaviour in that case.
1411
1412	Another thing you have to watch out for is that it is quite easy to	1621	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	1622	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	1623	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	1624	because there is no data. It is very easy to get into this situation even
1416	lot of those (for example Solaris ports), it is very easy to get into	1625	with a relatively standard program structure. Thus it is best to always
1417	this situation even with a relatively standard program structure. Thus	1626	use non-blocking I/O: An extra C<read>(2) returning C<EAGAIN> is far
1418	it is best to always use non-blocking I/O: An extra C<read>(2) returning
1419	C<EAGAIN> is far preferable to a program hanging until some data arrives.	1627	preferable to a program hanging until some data arrives.
1420		1628
1421	If you cannot run the fd in non-blocking mode (for example you should	1629	If you cannot run the fd in non-blocking mode (for example you should
1422	not play around with an Xlib connection), then you have to separately	1630	not play around with an Xlib connection), then you have to separately
1423	re-test whether a file descriptor is really ready with a known-to-be good	1631	re-test whether a file descriptor is really ready with a known-to-be good
1424	interface such as poll (fortunately in our Xlib example, Xlib already	1632	interface such as poll (fortunately in the case of Xlib, it already does
1425	does this on its own, so its quite safe to use). Some people additionally	1633	this on its own, so its quite safe to use). Some people additionally
1426	use C<SIGALRM> and an interval timer, just to be sure you won't block	1634	use C<SIGALRM> and an interval timer, just to be sure you won't block
1427	indefinitely.	1635	indefinitely.
1428		1636
1429	But really, best use non-blocking mode.	1637	But really, best use non-blocking mode.
1430		1638
…		…
1458		1666
1459	There is no workaround possible except not registering events	1667	There is no workaround possible except not registering events
1460	for potentially C<dup ()>'ed file descriptors, or to resort to	1668	for potentially C<dup ()>'ed file descriptors, or to resort to
1461	C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>.	1669	C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>.
1462		1670
		1671	=head3 The special problem of files
		1672
		1673	Many people try to use C<select> (or libev) on file descriptors
		1674	representing files, and expect it to become ready when their program
		1675	doesn't block on disk accesses (which can take a long time on their own).
		1676
		1677	However, this cannot ever work in the "expected" way - you get a readiness
		1678	notification as soon as the kernel knows whether and how much data is
		1679	there, and in the case of open files, that's always the case, so you
		1680	always get a readiness notification instantly, and your read (or possibly
		1681	write) will still block on the disk I/O.
		1682
		1683	Another way to view it is that in the case of sockets, pipes, character
		1684	devices and so on, there is another party (the sender) that delivers data
		1685	on it's own, but in the case of files, there is no such thing: the disk
		1686	will not send data on it's own, simply because it doesn't know what you
		1687	wish to read - you would first have to request some data.
		1688
		1689	Since files are typically not-so-well supported by advanced notification
		1690	mechanism, libev tries hard to emulate POSIX behaviour with respect
		1691	to files, even though you should not use it. The reason for this is
		1692	convenience: sometimes you want to watch STDIN or STDOUT, which is
		1693	usually a tty, often a pipe, but also sometimes files or special devices
		1694	(for example, C<epoll> on Linux works with F</dev/random> but not with
		1695	F</dev/urandom>), and even though the file might better be served with
		1696	asynchronous I/O instead of with non-blocking I/O, it is still useful when
		1697	it "just works" instead of freezing.
		1698
		1699	So avoid file descriptors pointing to files when you know it (e.g. use
		1700	libeio), but use them when it is convenient, e.g. for STDIN/STDOUT, or
		1701	when you rarely read from a file instead of from a socket, and want to
		1702	reuse the same code path.
		1703
1463	=head3 The special problem of fork	1704	=head3 The special problem of fork
1464		1705
1465	Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit	1706	Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit
1466	useless behaviour. Libev fully supports fork, but needs to be told about	1707	useless behaviour. Libev fully supports fork, but needs to be told about
1467	it in the child.	1708	it in the child if you want to continue to use it in the child.
1468		1709
1469	To support fork in your programs, you either have to call	1710	To support fork in your child processes, you have to call C<ev_loop_fork
1470	C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child,	1711	()> after a fork in the child, enable C<EVFLAG_FORKCHECK>, or resort to
1471	enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or	1712	C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>.
1472	C<EVBACKEND_POLL>.
1473		1713
1474	=head3 The special problem of SIGPIPE	1714	=head3 The special problem of SIGPIPE
1475		1715
1476	While not really specific to libev, it is easy to forget about C<SIGPIPE>:	1716	While not really specific to libev, it is easy to forget about C<SIGPIPE>:
1477	when writing to a pipe whose other end has been closed, your program gets	1717	when writing to a pipe whose other end has been closed, your program gets
…		…
1480		1720
1481	So when you encounter spurious, unexplained daemon exits, make sure you	1721	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	1722	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).	1723	somewhere, as that would have given you a big clue).
1484		1724
		1725	=head3 The special problem of accept()ing when you can't
		1726
		1727	Many implementations of the POSIX C<accept> function (for example,
		1728	found in post-2004 Linux) have the peculiar behaviour of not removing a
		1729	connection from the pending queue in all error cases.
		1730
		1731	For example, larger servers often run out of file descriptors (because
		1732	of resource limits), causing C<accept> to fail with C<ENFILE> but not
		1733	rejecting the connection, leading to libev signalling readiness on
		1734	the next iteration again (the connection still exists after all), and
		1735	typically causing the program to loop at 100% CPU usage.
		1736
		1737	Unfortunately, the set of errors that cause this issue differs between
		1738	operating systems, there is usually little the app can do to remedy the
		1739	situation, and no known thread-safe method of removing the connection to
		1740	cope with overload is known (to me).
		1741
		1742	One of the easiest ways to handle this situation is to just ignore it
		1743	- when the program encounters an overload, it will just loop until the
		1744	situation is over. While this is a form of busy waiting, no OS offers an
		1745	event-based way to handle this situation, so it's the best one can do.
		1746
		1747	A better way to handle the situation is to log any errors other than
		1748	C<EAGAIN> and C<EWOULDBLOCK>, making sure not to flood the log with such
		1749	messages, and continue as usual, which at least gives the user an idea of
		1750	what could be wrong ("raise the ulimit!"). For extra points one could stop
		1751	the C<ev_io> watcher on the listening fd "for a while", which reduces CPU
		1752	usage.
		1753
		1754	If your program is single-threaded, then you could also keep a dummy file
		1755	descriptor for overload situations (e.g. by opening F</dev/null>), and
		1756	when you run into C<ENFILE> or C<EMFILE>, close it, run C<accept>,
		1757	close that fd, and create a new dummy fd. This will gracefully refuse
		1758	clients under typical overload conditions.
		1759
		1760	The last way to handle it is to simply log the error and C<exit>, as
		1761	is often done with C<malloc> failures, but this results in an easy
		1762	opportunity for a DoS attack.
1485		1763
1486	=head3 Watcher-Specific Functions	1764	=head3 Watcher-Specific Functions
1487		1765
1488	=over 4	1766	=over 4
1489		1767
…		…
1521	...	1799	...
1522	struct ev_loop *loop = ev_default_init (0);	1800	struct ev_loop *loop = ev_default_init (0);
1523	ev_io stdin_readable;	1801	ev_io stdin_readable;
1524	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1802	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1525	ev_io_start (loop, &stdin_readable);	1803	ev_io_start (loop, &stdin_readable);
1526	ev_loop (loop, 0);	1804	ev_run (loop, 0);
1527		1805
1528		1806
1529	=head2 C<ev_timer> - relative and optionally repeating timeouts	1807	=head2 C<ev_timer> - relative and optionally repeating timeouts
1530		1808
1531	Timer watchers are simple relative timers that generate an event after a	1809	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	1818	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	1819	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	1820	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	1821	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	1822	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).	1823	no longer true when a callback calls C<ev_run> recursively).
1546		1824
1547	=head3 Be smart about timeouts	1825	=head3 Be smart about timeouts
1548		1826
1549	Many real-world problems involve some kind of timeout, usually for error	1827	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,	1828	recovery. A typical example is an HTTP request - if the other side hangs,
…		…
1636	ev_tstamp timeout = last_activity + 60.;	1914	ev_tstamp timeout = last_activity + 60.;
1637		1915
1638	// if last_activity + 60. is older than now, we did time out	1916	// if last_activity + 60. is older than now, we did time out
1639	if (timeout < now)	1917	if (timeout < now)
1640	{	1918	{
1641	// timeout occured, take action	1919	// timeout occurred, take action
1642	}	1920	}
1643	else	1921	else
1644	{	1922	{
1645	// callback was invoked, but there was some activity, re-arm	1923	// callback was invoked, but there was some activity, re-arm
1646	// the watcher to fire in last_activity + 60, which is	1924	// the watcher to fire in last_activity + 60, which is
…		…
1668	to the current time (meaning we just have some activity :), then call the	1946	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:	1947	callback, which will "do the right thing" and start the timer:
1670		1948
1671	ev_init (timer, callback);	1949	ev_init (timer, callback);
1672	last_activity = ev_now (loop);	1950	last_activity = ev_now (loop);
1673	callback (loop, timer, EV_TIMEOUT);	1951	callback (loop, timer, EV_TIMER);
1674		1952
1675	And when there is some activity, simply store the current time in	1953	And when there is some activity, simply store the current time in
1676	C<last_activity>, no libev calls at all:	1954	C<last_activity>, no libev calls at all:
1677		1955
1678	last_actiivty = ev_now (loop);	1956	last_activity = ev_now (loop);
1679		1957
1680	This technique is slightly more complex, but in most cases where the	1958	This technique is slightly more complex, but in most cases where the
1681	time-out is unlikely to be triggered, much more efficient.	1959	time-out is unlikely to be triggered, much more efficient.
1682		1960
1683	Changing the timeout is trivial as well (if it isn't hard-coded in the	1961	Changing the timeout is trivial as well (if it isn't hard-coded in the
…		…
1721		1999
1722	=head3 The special problem of time updates	2000	=head3 The special problem of time updates
1723		2001
1724	Establishing the current time is a costly operation (it usually takes at	2002	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	2003	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	2004	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	2005	growing difference between C<ev_now ()> and C<ev_time ()> when handling
1728	lots of events in one iteration.	2006	lots of events in one iteration.
1729		2007
1730	The relative timeouts are calculated relative to the C<ev_now ()>	2008	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	2009	time. This is usually the right thing as this timestamp refers to the time
…		…
1737		2015
1738	If the event loop is suspended for a long time, you can also force an	2016	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	2017	update of the time returned by C<ev_now ()> by calling C<ev_now_update
1740	()>.	2018	()>.
1741		2019
		2020	=head3 The special problems of suspended animation
		2021
		2022	When you leave the server world it is quite customary to hit machines that
		2023	can suspend/hibernate - what happens to the clocks during such a suspend?
		2024
		2025	Some quick tests made with a Linux 2.6.28 indicate that a suspend freezes
		2026	all processes, while the clocks (C<times>, C<CLOCK_MONOTONIC>) continue
		2027	to run until the system is suspended, but they will not advance while the
		2028	system is suspended. That means, on resume, it will be as if the program
		2029	was frozen for a few seconds, but the suspend time will not be counted
		2030	towards C<ev_timer> when a monotonic clock source is used. The real time
		2031	clock advanced as expected, but if it is used as sole clocksource, then a
		2032	long suspend would be detected as a time jump by libev, and timers would
		2033	be adjusted accordingly.
		2034
		2035	I would not be surprised to see different behaviour in different between
		2036	operating systems, OS versions or even different hardware.
		2037
		2038	The other form of suspend (job control, or sending a SIGSTOP) will see a
		2039	time jump in the monotonic clocks and the realtime clock. If the program
		2040	is suspended for a very long time, and monotonic clock sources are in use,
		2041	then you can expect C<ev_timer>s to expire as the full suspension time
		2042	will be counted towards the timers. When no monotonic clock source is in
		2043	use, then libev will again assume a timejump and adjust accordingly.
		2044
		2045	It might be beneficial for this latter case to call C<ev_suspend>
		2046	and C<ev_resume> in code that handles C<SIGTSTP>, to at least get
		2047	deterministic behaviour in this case (you can do nothing against
		2048	C<SIGSTOP>).
		2049
1742	=head3 Watcher-Specific Functions and Data Members	2050	=head3 Watcher-Specific Functions and Data Members
1743		2051
1744	=over 4	2052	=over 4
1745		2053
1746	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	2054	=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.	2080	C<repeat> value), or reset the running timer to the C<repeat> value.
1773		2081
1774	This sounds a bit complicated, see L<Be smart about timeouts>, above, for a	2082	This sounds a bit complicated, see L<Be smart about timeouts>, above, for a
1775	usage example.	2083	usage example.
1776		2084
		2085	=item ev_tstamp ev_timer_remaining (loop, ev_timer *)
		2086
		2087	Returns the remaining time until a timer fires. If the timer is active,
		2088	then this time is relative to the current event loop time, otherwise it's
		2089	the timeout value currently configured.
		2090
		2091	That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns
		2092	C<5>. When the timer is started and one second passes, C<ev_timer_remaining>
		2093	will return C<4>. When the timer expires and is restarted, it will return
		2094	roughly C<7> (likely slightly less as callback invocation takes some time,
		2095	too), and so on.
		2096
1777	=item ev_tstamp repeat [read-write]	2097	=item ev_tstamp repeat [read-write]
1778		2098
1779	The current C<repeat> value. Will be used each time the watcher times out	2099	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),	2100	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.	2101	which is also when any modifications are taken into account.
…		…
1806	}	2126	}
1807		2127
1808	ev_timer mytimer;	2128	ev_timer mytimer;
1809	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	2129	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1810	ev_timer_again (&mytimer); /* start timer */	2130	ev_timer_again (&mytimer); /* start timer */
1811	ev_loop (loop, 0);	2131	ev_run (loop, 0);
1812		2132
1813	// and in some piece of code that gets executed on any "activity":	2133	// and in some piece of code that gets executed on any "activity":
1814	// reset the timeout to start ticking again at 10 seconds	2134	// reset the timeout to start ticking again at 10 seconds
1815	ev_timer_again (&mytimer);	2135	ev_timer_again (&mytimer);
1816		2136
…		…
1842		2162
1843	As with timers, the callback is guaranteed to be invoked only when the	2163	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	2164	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	2165	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	2166	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).	2167	(but this is no longer true when a callback calls C<ev_run> recursively).
1848		2168
1849	=head3 Watcher-Specific Functions and Data Members	2169	=head3 Watcher-Specific Functions and Data Members
1850		2170
1851	=over 4	2171	=over 4
1852		2172
…		…
1980	Example: Call a callback every hour, or, more precisely, whenever the	2300	Example: Call a callback every hour, or, more precisely, whenever the
1981	system time is divisible by 3600. The callback invocation times have	2301	system time is divisible by 3600. The callback invocation times have
1982	potentially a lot of jitter, but good long-term stability.	2302	potentially a lot of jitter, but good long-term stability.
1983		2303
1984	static void	2304	static void
1985	clock_cb (struct ev_loop *loop, ev_io *w, int revents)	2305	clock_cb (struct ev_loop *loop, ev_periodic *w, int revents)
1986	{	2306	{
1987	... its now a full hour (UTC, or TAI or whatever your clock follows)	2307	... its now a full hour (UTC, or TAI or whatever your clock follows)
1988	}	2308	}
1989		2309
1990	ev_periodic hourly_tick;	2310	ev_periodic hourly_tick;
…		…
2013		2333
2014	=head2 C<ev_signal> - signal me when a signal gets signalled!	2334	=head2 C<ev_signal> - signal me when a signal gets signalled!
2015		2335
2016	Signal watchers will trigger an event when the process receives a specific	2336	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	2337	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	2338	will try its best to deliver signals synchronously, i.e. as part of the
2019	normal event processing, like any other event.	2339	normal event processing, like any other event.
2020		2340
2021	If you want signals asynchronously, just use C<sigaction> as you would	2341	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	2342	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.	2343	the signal. You can even use C<ev_async> from a signal handler to
		2344	synchronously wake up an event loop.
2024		2345
2025	You can configure as many watchers as you like per signal. Only when the	2346	You can configure as many watchers as you like for the same signal, but
		2347	only within the same loop, i.e. you can watch for C<SIGINT> in your
		2348	default loop and for C<SIGIO> in another loop, but you cannot watch for
		2349	C<SIGINT> in both the default loop and another loop at the same time. At
		2350	the moment, C<SIGCHLD> is permanently tied to the default loop.
		2351
2026	first watcher gets started will libev actually register a signal handler	2352	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	2353	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	2354	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		2355
2032	If possible and supported, libev will install its handlers with	2356	If possible and supported, libev will install its handlers with
2033	C<SA_RESTART> behaviour enabled, so system calls should not be unduly	2357	C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should
2034	interrupted. If you have a problem with system calls getting interrupted by	2358	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	2359	interrupted by signals you can block all signals in an C<ev_check> watcher
2036	them in an C<ev_prepare> watcher.	2360	and unblock them in an C<ev_prepare> watcher.
		2361
		2362	=head3 The special problem of inheritance over fork/execve/pthread_create
		2363
		2364	Both the signal mask (C<sigprocmask>) and the signal disposition
		2365	(C<sigaction>) are unspecified after starting a signal watcher (and after
		2366	stopping it again), that is, libev might or might not block the signal,
		2367	and might or might not set or restore the installed signal handler.
		2368
		2369	While this does not matter for the signal disposition (libev never
		2370	sets signals to C<SIG_IGN>, so handlers will be reset to C<SIG_DFL> on
		2371	C<execve>), this matters for the signal mask: many programs do not expect
		2372	certain signals to be blocked.
		2373
		2374	This means that before calling C<exec> (from the child) you should reset
		2375	the signal mask to whatever "default" you expect (all clear is a good
		2376	choice usually).
		2377
		2378	The simplest way to ensure that the signal mask is reset in the child is
		2379	to install a fork handler with C<pthread_atfork> that resets it. That will
		2380	catch fork calls done by libraries (such as the libc) as well.
		2381
		2382	In current versions of libev, the signal will not be blocked indefinitely
		2383	unless you use the C<signalfd> API (C<EV_SIGNALFD>). While this reduces
		2384	the window of opportunity for problems, it will not go away, as libev
		2385	I<has> to modify the signal mask, at least temporarily.
		2386
		2387	So I can't stress this enough: I<If you do not reset your signal mask when
		2388	you expect it to be empty, you have a race condition in your code>. This
		2389	is not a libev-specific thing, this is true for most event libraries.
		2390
		2391	=head3 The special problem of threads signal handling
		2392
		2393	POSIX threads has problematic signal handling semantics, specifically,
		2394	a lot of functionality (sigfd, sigwait etc.) only really works if all
		2395	threads in a process block signals, which is hard to achieve.
		2396
		2397	When you want to use sigwait (or mix libev signal handling with your own
		2398	for the same signals), you can tackle this problem by globally blocking
		2399	all signals before creating any threads (or creating them with a fully set
		2400	sigprocmask) and also specifying the C<EVFLAG_NOSIGMASK> when creating
		2401	loops. Then designate one thread as "signal receiver thread" which handles
		2402	these signals. You can pass on any signals that libev might be interested
		2403	in by calling C<ev_feed_signal>.
2037		2404
2038	=head3 Watcher-Specific Functions and Data Members	2405	=head3 Watcher-Specific Functions and Data Members
2039		2406
2040	=over 4	2407	=over 4
2041		2408
…		…
2057	Example: Try to exit cleanly on SIGINT.	2424	Example: Try to exit cleanly on SIGINT.
2058		2425
2059	static void	2426	static void
2060	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)	2427	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)
2061	{	2428	{
2062	ev_unloop (loop, EVUNLOOP_ALL);	2429	ev_break (loop, EVBREAK_ALL);
2063	}	2430	}
2064		2431
2065	ev_signal signal_watcher;	2432	ev_signal signal_watcher;
2066	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	2433	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
2067	ev_signal_start (loop, &signal_watcher);	2434	ev_signal_start (loop, &signal_watcher);
…		…
2086	libev)	2453	libev)
2087		2454
2088	=head3 Process Interaction	2455	=head3 Process Interaction
2089		2456
2090	Libev grabs C<SIGCHLD> as soon as the default event loop is	2457	Libev grabs C<SIGCHLD> as soon as the default event loop is
2091	initialised. This is necessary to guarantee proper behaviour even if	2458	initialised. This is necessary to guarantee proper behaviour even if the
2092	the first child watcher is started after the child exits. The occurrence	2459	first child watcher is started after the child exits. The occurrence
2093	of C<SIGCHLD> is recorded asynchronously, but child reaping is done	2460	of C<SIGCHLD> is recorded asynchronously, but child reaping is done
2094	synchronously as part of the event loop processing. Libev always reaps all	2461	synchronously as part of the event loop processing. Libev always reaps all
2095	children, even ones not watched.	2462	children, even ones not watched.
2096		2463
2097	=head3 Overriding the Built-In Processing	2464	=head3 Overriding the Built-In Processing
…		…
2107	=head3 Stopping the Child Watcher	2474	=head3 Stopping the Child Watcher
2108		2475
2109	Currently, the child watcher never gets stopped, even when the	2476	Currently, the child watcher never gets stopped, even when the
2110	child terminates, so normally one needs to stop the watcher in the	2477	child terminates, so normally one needs to stop the watcher in the
2111	callback. Future versions of libev might stop the watcher automatically	2478	callback. Future versions of libev might stop the watcher automatically
2112	when a child exit is detected.	2479	when a child exit is detected (calling C<ev_child_stop> twice is not a
		2480	problem).
2113		2481
2114	=head3 Watcher-Specific Functions and Data Members	2482	=head3 Watcher-Specific Functions and Data Members
2115		2483
2116	=over 4	2484	=over 4
2117		2485
…		…
2452		2820
2453	Prepare and check watchers are usually (but not always) used in pairs:	2821	Prepare and check watchers are usually (but not always) used in pairs:
2454	prepare watchers get invoked before the process blocks and check watchers	2822	prepare watchers get invoked before the process blocks and check watchers
2455	afterwards.	2823	afterwards.
2456		2824
2457	You I<must not> call C<ev_loop> or similar functions that enter	2825	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>	2826	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	2827	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	2828	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,	2829	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	2830	C<ev_check> so if you have one watcher of each kind they will always be
…		…
2630		2998
2631	if (timeout >= 0)	2999	if (timeout >= 0)
2632	// create/start timer	3000	// create/start timer
2633		3001
2634	// poll	3002	// poll
2635	ev_loop (EV_A_ 0);	3003	ev_run (EV_A_ 0);
2636		3004
2637	// stop timer again	3005	// stop timer again
2638	if (timeout >= 0)	3006	if (timeout >= 0)
2639	ev_timer_stop (EV_A_ &to);	3007	ev_timer_stop (EV_A_ &to);
2640		3008
…		…
2718	if you do not want that, you need to temporarily stop the embed watcher).	3086	if you do not want that, you need to temporarily stop the embed watcher).
2719		3087
2720	=item ev_embed_sweep (loop, ev_embed *)	3088	=item ev_embed_sweep (loop, ev_embed *)
2721		3089
2722	Make a single, non-blocking sweep over the embedded loop. This works	3090	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	3091	similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most
2724	appropriate way for embedded loops.	3092	appropriate way for embedded loops.
2725		3093
2726	=item struct ev_loop *other [read-only]	3094	=item struct ev_loop *other [read-only]
2727		3095
2728	The embedded event loop.	3096	The embedded event loop.
…		…
2788	C<ev_default_fork> cheats and calls it in the wrong process, the fork	3156	C<ev_default_fork> cheats and calls it in the wrong process, the fork
2789	handlers will be invoked, too, of course.	3157	handlers will be invoked, too, of course.
2790		3158
2791	=head3 The special problem of life after fork - how is it possible?	3159	=head3 The special problem of life after fork - how is it possible?
2792		3160
2793	Most uses of C<fork()> consist of forking, then some simple calls to ste	3161	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	3162	up/change the process environment, followed by a call to C<exec()>. This
2795	sequence should be handled by libev without any problems.	3163	sequence should be handled by libev without any problems.
2796		3164
2797	This changes when the application actually wants to do event handling	3165	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	3166	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	3182	disadvantage of having to use multiple event loops (which do not support
2815	signal watchers).	3183	signal watchers).
2816		3184
2817	When this is not possible, or you want to use the default loop for	3185	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	3186	other reasons, then in the process that wants to start "fresh", call
2819	C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying	3187	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	3188	Destroying the default loop will "orphan" (not stop) all registered
2821	have to be careful not to execute code that modifies those watchers. Note	3189	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.	3190	those watchers. Note also that in that case, you have to re-register any
		3191	signal watchers.
2823		3192
2824	=head3 Watcher-Specific Functions and Data Members	3193	=head3 Watcher-Specific Functions and Data Members
2825		3194
2826	=over 4	3195	=over 4
2827		3196
2828	=item ev_fork_init (ev_signal *, callback)	3197	=item ev_fork_init (ev_fork *, callback)
2829		3198
2830	Initialises and configures the fork watcher - it has no parameters of any	3199	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,	3200	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
2832	believe me.	3201	really.
2833		3202
2834	=back	3203	=back
2835		3204
2836		3205
		3206	=head2 C<ev_cleanup> - even the best things end
		3207
		3208	Cleanup watchers are called just before the event loop is being destroyed
		3209	by a call to C<ev_loop_destroy>.
		3210
		3211	While there is no guarantee that the event loop gets destroyed, cleanup
		3212	watchers provide a convenient method to install cleanup hooks for your
		3213	program, worker threads and so on - you just to make sure to destroy the
		3214	loop when you want them to be invoked.
		3215
		3216	Cleanup watchers are invoked in the same way as any other watcher. Unlike
		3217	all other watchers, they do not keep a reference to the event loop (which
		3218	makes a lot of sense if you think about it). Like all other watchers, you
		3219	can call libev functions in the callback, except C<ev_cleanup_start>.
		3220
		3221	=head3 Watcher-Specific Functions and Data Members
		3222
		3223	=over 4
		3224
		3225	=item ev_cleanup_init (ev_cleanup *, callback)
		3226
		3227	Initialises and configures the cleanup watcher - it has no parameters of
		3228	any kind. There is a C<ev_cleanup_set> macro, but using it is utterly
		3229	pointless, I assure you.
		3230
		3231	=back
		3232
		3233	Example: Register an atexit handler to destroy the default loop, so any
		3234	cleanup functions are called.
		3235
		3236	static void
		3237	program_exits (void)
		3238	{
		3239	ev_loop_destroy (EV_DEFAULT_UC);
		3240	}
		3241
		3242	...
		3243	atexit (program_exits);
		3244
		3245
2837	=head2 C<ev_async> - how to wake up another event loop	3246	=head2 C<ev_async> - how to wake up an event loop
2838		3247
2839	In general, you cannot use an C<ev_loop> from multiple threads or other	3248	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	3249	asynchronous sources such as signal handlers (as opposed to multiple event
2841	loops - those are of course safe to use in different threads).	3250	loops - those are of course safe to use in different threads).
2842		3251
2843	Sometimes, however, you need to wake up another event loop you do not	3252	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	3253	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	3254	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	3255	it by calling C<ev_async_send>, which is thread- and signal safe.
2847	safe.
2848		3256
2849	This functionality is very similar to C<ev_signal> watchers, as signals,	3257	This functionality is very similar to C<ev_signal> watchers, as signals,
2850	too, are asynchronous in nature, and signals, too, will be compressed	3258	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	3259	(i.e. the number of callback invocations may be less than the number of
2852	C<ev_async_sent> calls).	3260	C<ev_async_sent> calls). In fact, you could use signal watchers as a kind
		3261	of "global async watchers" by using a watcher on an otherwise unused
		3262	signal, and C<ev_feed_signal> to signal this watcher from another thread,
		3263	even without knowing which loop owns the signal.
2853		3264
2854	Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not	3265	Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not
2855	just the default loop.	3266	just the default loop.
2856		3267
2857	=head3 Queueing	3268	=head3 Queueing
2858		3269
2859	C<ev_async> does not support queueing of data in any way. The reason	3270	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	3271	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	3272	multiple-writer-single-reader queue that works in all cases and doesn't
2862	need elaborate support such as pthreads.	3273	need elaborate support such as pthreads or unportable memory access
		3274	semantics.
2863		3275
2864	That means that if you want to queue data, you have to provide your own	3276	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	3277	queue. But at least I can tell you how to implement locking around your
2866	queue:	3278	queue:
2867		3279
…		…
3006		3418
3007	If C<timeout> is less than 0, then no timeout watcher will be	3419	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	3420	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and
3009	repeat = 0) will be started. C<0> is a valid timeout.	3421	repeat = 0) will be started. C<0> is a valid timeout.
3010		3422
3011	The callback has the type C<void (*cb)(int revents, void *arg)> and gets	3423	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	3424	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>	3425	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>	3426	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	3427	a timeout and an io event at the same time - you probably should give io
3016	events precedence.	3428	events precedence.
3017		3429
3018	Example: wait up to ten seconds for data to appear on STDIN_FILENO.	3430	Example: wait up to ten seconds for data to appear on STDIN_FILENO.
3019		3431
3020	static void stdin_ready (int revents, void *arg)	3432	static void stdin_ready (int revents, void *arg)
3021	{	3433	{
3022	if (revents & EV_READ)	3434	if (revents & EV_READ)
3023	/* stdin might have data for us, joy! */;	3435	/* stdin might have data for us, joy! */;
3024	else if (revents & EV_TIMEOUT)	3436	else if (revents & EV_TIMER)
3025	/* doh, nothing entered */;	3437	/* doh, nothing entered */;
3026	}	3438	}
3027		3439
3028	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	3440	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
3029		3441
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)	3442	=item ev_feed_fd_event (loop, int fd, int revents)
3037		3443
3038	Feed an event on the given fd, as if a file descriptor backend detected	3444	Feed an event on the given fd, as if a file descriptor backend detected
3039	the given events it.	3445	the given events it.
3040		3446
3041	=item ev_feed_signal_event (struct ev_loop *loop, int signum)	3447	=item ev_feed_signal_event (loop, int signum)
3042		3448
3043	Feed an event as if the given signal occurred (C<loop> must be the default	3449	Feed an event as if the given signal occurred. See also C<ev_feed_signal>,
3044	loop!).	3450	which is async-safe.
		3451
		3452	=back
		3453
		3454
		3455	=head1 COMMON OR USEFUL IDIOMS (OR BOTH)
		3456
		3457	This section explains some common idioms that are not immediately
		3458	obvious. Note that examples are sprinkled over the whole manual, and this
		3459	section only contains stuff that wouldn't fit anywhere else.
		3460
		3461	=over 4
		3462
		3463	=item Model/nested event loop invocations and exit conditions.
		3464
		3465	Often (especially in GUI toolkits) there are places where you have
		3466	I<modal> interaction, which is most easily implemented by recursively
		3467	invoking C<ev_run>.
		3468
		3469	This brings the problem of exiting - a callback might want to finish the
		3470	main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but
		3471	a modal "Are you sure?" dialog is still waiting), or just the nested one
		3472	and not the main one (e.g. user clocked "Ok" in a modal dialog), or some
		3473	other combination: In these cases, C<ev_break> will not work alone.
		3474
		3475	The solution is to maintain "break this loop" variable for each C<ev_run>
		3476	invocation, and use a loop around C<ev_run> until the condition is
		3477	triggered, using C<EVRUN_ONCE>:
		3478
		3479	// main loop
		3480	int exit_main_loop = 0;
		3481
		3482	while (!exit_main_loop)
		3483	ev_run (EV_DEFAULT_ EVRUN_ONCE);
		3484
		3485	// in a model watcher
		3486	int exit_nested_loop = 0;
		3487
		3488	while (!exit_nested_loop)
		3489	ev_run (EV_A_ EVRUN_ONCE);
		3490
		3491	To exit from any of these loops, just set the corresponding exit variable:
		3492
		3493	// exit modal loop
		3494	exit_nested_loop = 1;
		3495
		3496	// exit main program, after modal loop is finished
		3497	exit_main_loop = 1;
		3498
		3499	// exit both
		3500	exit_main_loop = exit_nested_loop = 1;
		3501
		3502	=item Thread locking example
		3503
		3504	Here is a fictitious example of how to run an event loop in a different
		3505	thread than where callbacks are being invoked and watchers are
		3506	created/added/removed.
		3507
		3508	For a real-world example, see the C<EV::Loop::Async> perl module,
		3509	which uses exactly this technique (which is suited for many high-level
		3510	languages).
		3511
		3512	The example uses a pthread mutex to protect the loop data, a condition
		3513	variable to wait for callback invocations, an async watcher to notify the
		3514	event loop thread and an unspecified mechanism to wake up the main thread.
		3515
		3516	First, you need to associate some data with the event loop:
		3517
		3518	typedef struct {
		3519	mutex_t lock; /* global loop lock */
		3520	ev_async async_w;
		3521	thread_t tid;
		3522	cond_t invoke_cv;
		3523	} userdata;
		3524
		3525	void prepare_loop (EV_P)
		3526	{
		3527	// for simplicity, we use a static userdata struct.
		3528	static userdata u;
		3529
		3530	ev_async_init (&u->async_w, async_cb);
		3531	ev_async_start (EV_A_ &u->async_w);
		3532
		3533	pthread_mutex_init (&u->lock, 0);
		3534	pthread_cond_init (&u->invoke_cv, 0);
		3535
		3536	// now associate this with the loop
		3537	ev_set_userdata (EV_A_ u);
		3538	ev_set_invoke_pending_cb (EV_A_ l_invoke);
		3539	ev_set_loop_release_cb (EV_A_ l_release, l_acquire);
		3540
		3541	// then create the thread running ev_loop
		3542	pthread_create (&u->tid, 0, l_run, EV_A);
		3543	}
		3544
		3545	The callback for the C<ev_async> watcher does nothing: the watcher is used
		3546	solely to wake up the event loop so it takes notice of any new watchers
		3547	that might have been added:
		3548
		3549	static void
		3550	async_cb (EV_P_ ev_async *w, int revents)
		3551	{
		3552	// just used for the side effects
		3553	}
		3554
		3555	The C<l_release> and C<l_acquire> callbacks simply unlock/lock the mutex
		3556	protecting the loop data, respectively.
		3557
		3558	static void
		3559	l_release (EV_P)
		3560	{
		3561	userdata *u = ev_userdata (EV_A);
		3562	pthread_mutex_unlock (&u->lock);
		3563	}
		3564
		3565	static void
		3566	l_acquire (EV_P)
		3567	{
		3568	userdata *u = ev_userdata (EV_A);
		3569	pthread_mutex_lock (&u->lock);
		3570	}
		3571
		3572	The event loop thread first acquires the mutex, and then jumps straight
		3573	into C<ev_run>:
		3574
		3575	void *
		3576	l_run (void *thr_arg)
		3577	{
		3578	struct ev_loop *loop = (struct ev_loop *)thr_arg;
		3579
		3580	l_acquire (EV_A);
		3581	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
		3582	ev_run (EV_A_ 0);
		3583	l_release (EV_A);
		3584
		3585	return 0;
		3586	}
		3587
		3588	Instead of invoking all pending watchers, the C<l_invoke> callback will
		3589	signal the main thread via some unspecified mechanism (signals? pipe
		3590	writes? C<Async::Interrupt>?) and then waits until all pending watchers
		3591	have been called (in a while loop because a) spurious wakeups are possible
		3592	and b) skipping inter-thread-communication when there are no pending
		3593	watchers is very beneficial):
		3594
		3595	static void
		3596	l_invoke (EV_P)
		3597	{
		3598	userdata *u = ev_userdata (EV_A);
		3599
		3600	while (ev_pending_count (EV_A))
		3601	{
		3602	wake_up_other_thread_in_some_magic_or_not_so_magic_way ();
		3603	pthread_cond_wait (&u->invoke_cv, &u->lock);
		3604	}
		3605	}
		3606
		3607	Now, whenever the main thread gets told to invoke pending watchers, it
		3608	will grab the lock, call C<ev_invoke_pending> and then signal the loop
		3609	thread to continue:
		3610
		3611	static void
		3612	real_invoke_pending (EV_P)
		3613	{
		3614	userdata *u = ev_userdata (EV_A);
		3615
		3616	pthread_mutex_lock (&u->lock);
		3617	ev_invoke_pending (EV_A);
		3618	pthread_cond_signal (&u->invoke_cv);
		3619	pthread_mutex_unlock (&u->lock);
		3620	}
		3621
		3622	Whenever you want to start/stop a watcher or do other modifications to an
		3623	event loop, you will now have to lock:
		3624
		3625	ev_timer timeout_watcher;
		3626	userdata *u = ev_userdata (EV_A);
		3627
		3628	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
		3629
		3630	pthread_mutex_lock (&u->lock);
		3631	ev_timer_start (EV_A_ &timeout_watcher);
		3632	ev_async_send (EV_A_ &u->async_w);
		3633	pthread_mutex_unlock (&u->lock);
		3634
		3635	Note that sending the C<ev_async> watcher is required because otherwise
		3636	an event loop currently blocking in the kernel will have no knowledge
		3637	about the newly added timer. By waking up the loop it will pick up any new
		3638	watchers in the next event loop iteration.
3045		3639
3046	=back	3640	=back
3047		3641
3048		3642
3049	=head1 LIBEVENT EMULATION	3643	=head1 LIBEVENT EMULATION
3050		3644
3051	Libev offers a compatibility emulation layer for libevent. It cannot	3645	Libev offers a compatibility emulation layer for libevent. It cannot
3052	emulate the internals of libevent, so here are some usage hints:	3646	emulate the internals of libevent, so here are some usage hints:
3053		3647
3054	=over 4	3648	=over 4
		3649
		3650	=item * Only the libevent-1.4.1-beta API is being emulated.
		3651
		3652	This was the newest libevent version available when libev was implemented,
		3653	and is still mostly unchanged in 2010.
3055		3654
3056	=item * Use it by including <event.h>, as usual.	3655	=item * Use it by including <event.h>, as usual.
3057		3656
3058	=item * The following members are fully supported: ev_base, ev_callback,	3657	=item * The following members are fully supported: ev_base, ev_callback,
3059	ev_arg, ev_fd, ev_res, ev_events.	3658	ev_arg, ev_fd, ev_res, ev_events.
…		…
3065	=item * Priorities are not currently supported. Initialising priorities	3664	=item * Priorities are not currently supported. Initialising priorities
3066	will fail and all watchers will have the same priority, even though there	3665	will fail and all watchers will have the same priority, even though there
3067	is an ev_pri field.	3666	is an ev_pri field.
3068		3667
3069	=item * In libevent, the last base created gets the signals, in libev, the	3668	=item * In libevent, the last base created gets the signals, in libev, the
3070	first base created (== the default loop) gets the signals.	3669	base that registered the signal gets the signals.
3071		3670
3072	=item * Other members are not supported.	3671	=item * Other members are not supported.
3073		3672
3074	=item * The libev emulation is I<not> ABI compatible to libevent, you need	3673	=item * The libev emulation is I<not> ABI compatible to libevent, you need
3075	to use the libev header file and library.	3674	to use the libev header file and library.
…		…
3094	Care has been taken to keep the overhead low. The only data member the C++	3693	Care has been taken to keep the overhead low. The only data member the C++
3095	classes add (compared to plain C-style watchers) is the event loop pointer	3694	classes add (compared to plain C-style watchers) is the event loop pointer
3096	that the watcher is associated with (or no additional members at all if	3695	that the watcher is associated with (or no additional members at all if
3097	you disable C<EV_MULTIPLICITY> when embedding libev).	3696	you disable C<EV_MULTIPLICITY> when embedding libev).
3098		3697
3099	Currently, functions, and static and non-static member functions can be	3698	Currently, functions, static and non-static member functions and classes
3100	used as callbacks. Other types should be easy to add as long as they only	3699	with C<operator ()> can be used as callbacks. Other types should be easy
3101	need one additional pointer for context. If you need support for other	3700	to add as long as they only need one additional pointer for context. If
3102	types of functors please contact the author (preferably after implementing	3701	you need support for other types of functors please contact the author
3103	it).	3702	(preferably after implementing it).
3104		3703
3105	Here is a list of things available in the C<ev> namespace:	3704	Here is a list of things available in the C<ev> namespace:
3106		3705
3107	=over 4	3706	=over 4
3108		3707
…		…
3126		3725
3127	=over 4	3726	=over 4
3128		3727
3129	=item ev::TYPE::TYPE ()	3728	=item ev::TYPE::TYPE ()
3130		3729
3131	=item ev::TYPE::TYPE (struct ev_loop *)	3730	=item ev::TYPE::TYPE (loop)
3132		3731
3133	=item ev::TYPE::~TYPE	3732	=item ev::TYPE::~TYPE
3134		3733
3135	The constructor (optionally) takes an event loop to associate the watcher	3734	The constructor (optionally) takes an event loop to associate the watcher
3136	with. If it is omitted, it will use C<EV_DEFAULT>.	3735	with. If it is omitted, it will use C<EV_DEFAULT>.
…		…
3169	myclass obj;	3768	myclass obj;
3170	ev::io iow;	3769	ev::io iow;
3171	iow.set <myclass, &myclass::io_cb> (&obj);	3770	iow.set <myclass, &myclass::io_cb> (&obj);
3172		3771
3173	=item w->set (object *)	3772	=item w->set (object *)
3174
3175	This is an B<experimental> feature that might go away in a future version.
3176		3773
3177	This is a variation of a method callback - leaving out the method to call	3774	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	3775	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	3776	functor objects without having to manually specify the C<operator ()> all
3180	the time. Incidentally, you can then also leave out the template argument	3777	the time. Incidentally, you can then also leave out the template argument
…		…
3213	Example: Use a plain function as callback.	3810	Example: Use a plain function as callback.
3214		3811
3215	static void io_cb (ev::io &w, int revents) { }	3812	static void io_cb (ev::io &w, int revents) { }
3216	iow.set <io_cb> ();	3813	iow.set <io_cb> ();
3217		3814
3218	=item w->set (struct ev_loop *)	3815	=item w->set (loop)
3219		3816
3220	Associates a different C<struct ev_loop> with this watcher. You can only	3817	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).	3818	do this when the watcher is inactive (and not pending either).
3222		3819
3223	=item w->set ([arguments])	3820	=item w->set ([arguments])
3224		3821
3225	Basically the same as C<ev_TYPE_set>, with the same arguments. Must be	3822	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	3823	method or a suitable start method must be called at least once. Unlike the
3227	automatically stopped and restarted when reconfiguring it with this	3824	C counterpart, an active watcher gets automatically stopped and restarted
3228	method.	3825	when reconfiguring it with this method.
3229		3826
3230	=item w->start ()	3827	=item w->start ()
3231		3828
3232	Starts the watcher. Note that there is no C<loop> argument, as the	3829	Starts the watcher. Note that there is no C<loop> argument, as the
3233	constructor already stores the event loop.	3830	constructor already stores the event loop.
3234		3831
		3832	=item w->start ([arguments])
		3833
		3834	Instead of calling C<set> and C<start> methods separately, it is often
		3835	convenient to wrap them in one call. Uses the same type of arguments as
		3836	the configure C<set> method of the watcher.
		3837
3235	=item w->stop ()	3838	=item w->stop ()
3236		3839
3237	Stops the watcher if it is active. Again, no C<loop> argument.	3840	Stops the watcher if it is active. Again, no C<loop> argument.
3238		3841
3239	=item w->again () (C<ev::timer>, C<ev::periodic> only)	3842	=item w->again () (C<ev::timer>, C<ev::periodic> only)
…		…
3251		3854
3252	=back	3855	=back
3253		3856
3254	=back	3857	=back
3255		3858
3256	Example: Define a class with an IO and idle watcher, start one of them in	3859	Example: Define a class with two I/O and idle watchers, start the I/O
3257	the constructor.	3860	watchers in the constructor.
3258		3861
3259	class myclass	3862	class myclass
3260	{	3863	{
3261	ev::io io ; void io_cb (ev::io &w, int revents);	3864	ev::io io ; void io_cb (ev::io &w, int revents);
		3865	ev::io2 io2 ; void io2_cb (ev::io &w, int revents);
3262	ev::idle idle; void idle_cb (ev::idle &w, int revents);	3866	ev::idle idle; void idle_cb (ev::idle &w, int revents);
3263		3867
3264	myclass (int fd)	3868	myclass (int fd)
3265	{	3869	{
3266	io .set <myclass, &myclass::io_cb > (this);	3870	io .set <myclass, &myclass::io_cb > (this);
		3871	io2 .set <myclass, &myclass::io2_cb > (this);
3267	idle.set <myclass, &myclass::idle_cb> (this);	3872	idle.set <myclass, &myclass::idle_cb> (this);
3268		3873
3269	io.start (fd, ev::READ);	3874	io.set (fd, ev::WRITE); // configure the watcher
		3875	io.start (); // start it whenever convenient
		3876
		3877	io2.start (fd, ev::READ); // set + start in one call
3270	}	3878	}
3271	};	3879	};
3272		3880
3273		3881
3274	=head1 OTHER LANGUAGE BINDINGS	3882	=head1 OTHER LANGUAGE BINDINGS
…		…
3320	=item Ocaml	3928	=item Ocaml
3321		3929
3322	Erkki Seppala has written Ocaml bindings for libev, to be found at	3930	Erkki Seppala has written Ocaml bindings for libev, to be found at
3323	L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>.	3931	L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>.
3324		3932
		3933	=item Lua
		3934
		3935	Brian Maher has written a partial interface to libev for lua (at the
		3936	time of this writing, only C<ev_io> and C<ev_timer>), to be found at
		3937	L<http://github.com/brimworks/lua-ev>.
		3938
3325	=back	3939	=back
3326		3940
3327		3941
3328	=head1 MACRO MAGIC	3942	=head1 MACRO MAGIC
3329		3943
…		…
3342	loop argument"). The C<EV_A> form is used when this is the sole argument,	3956	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:	3957	C<EV_A_> is used when other arguments are following. Example:
3344		3958
3345	ev_unref (EV_A);	3959	ev_unref (EV_A);
3346	ev_timer_add (EV_A_ watcher);	3960	ev_timer_add (EV_A_ watcher);
3347	ev_loop (EV_A_ 0);	3961	ev_run (EV_A_ 0);
3348		3962
3349	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	3963	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
3350	which is often provided by the following macro.	3964	which is often provided by the following macro.
3351		3965
3352	=item C<EV_P>, C<EV_P_>	3966	=item C<EV_P>, C<EV_P_>
…		…
3392	}	4006	}
3393		4007
3394	ev_check check;	4008	ev_check check;
3395	ev_check_init (&check, check_cb);	4009	ev_check_init (&check, check_cb);
3396	ev_check_start (EV_DEFAULT_ &check);	4010	ev_check_start (EV_DEFAULT_ &check);
3397	ev_loop (EV_DEFAULT_ 0);	4011	ev_run (EV_DEFAULT_ 0);
3398		4012
3399	=head1 EMBEDDING	4013	=head1 EMBEDDING
3400		4014
3401	Libev can (and often is) directly embedded into host	4015	Libev can (and often is) directly embedded into host
3402	applications. Examples of applications that embed it include the Deliantra	4016	applications. Examples of applications that embed it include the Deliantra
…		…
3482	libev.m4	4096	libev.m4
3483		4097
3484	=head2 PREPROCESSOR SYMBOLS/MACROS	4098	=head2 PREPROCESSOR SYMBOLS/MACROS
3485		4099
3486	Libev can be configured via a variety of preprocessor symbols you have to	4100	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	4101	define before including (or compiling) any of its files. The default in
3488	autoconf is documented for every option.	4102	the absence of autoconf is documented for every option.
		4103
		4104	Symbols marked with "(h)" do not change the ABI, and can have different
		4105	values when compiling libev vs. including F<ev.h>, so it is permissible
		4106	to redefine them before including F<ev.h> without breaking compatibility
		4107	to a compiled library. All other symbols change the ABI, which means all
		4108	users of libev and the libev code itself must be compiled with compatible
		4109	settings.
3489		4110
3490	=over 4	4111	=over 4
3491		4112
		4113	=item EV_COMPAT3 (h)
		4114
		4115	Backwards compatibility is a major concern for libev. This is why this
		4116	release of libev comes with wrappers for the functions and symbols that
		4117	have been renamed between libev version 3 and 4.
		4118
		4119	You can disable these wrappers (to test compatibility with future
		4120	versions) by defining C<EV_COMPAT3> to C<0> when compiling your
		4121	sources. This has the additional advantage that you can drop the C<struct>
		4122	from C<struct ev_loop> declarations, as libev will provide an C<ev_loop>
		4123	typedef in that case.
		4124
		4125	In some future version, the default for C<EV_COMPAT3> will become C<0>,
		4126	and in some even more future version the compatibility code will be
		4127	removed completely.
		4128
3492	=item EV_STANDALONE	4129	=item EV_STANDALONE (h)
3493		4130
3494	Must always be C<1> if you do not use autoconf configuration, which	4131	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	4132	keeps libev from including F<config.h>, and it also defines dummy
3496	implementations for some libevent functions (such as logging, which is not	4133	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	4134	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.	4135	F<event.h> that are not directly supported by the libev core alone.
3499		4136
3500	In stanbdalone mode, libev will still try to automatically deduce the	4137	In standalone mode, libev will still try to automatically deduce the
3501	configuration, but has to be more conservative.	4138	configuration, but has to be more conservative.
3502		4139
3503	=item EV_USE_MONOTONIC	4140	=item EV_USE_MONOTONIC
3504		4141
3505	If defined to be C<1>, libev will try to detect the availability of the	4142	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	4207	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,	4208	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	4209	it is assumed that all these functions actually work on fds, even
3573	on win32. Should not be defined on non-win32 platforms.	4210	on win32. Should not be defined on non-win32 platforms.
3574		4211
3575	=item EV_FD_TO_WIN32_HANDLE	4212	=item EV_FD_TO_WIN32_HANDLE(fd)
3576		4213
3577	If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map	4214	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	4215	file descriptors to socket handles. When not defining this symbol (the
3579	default), then libev will call C<_get_osfhandle>, which is usually	4216	default), then libev will call C<_get_osfhandle>, which is usually
3580	correct. In some cases, programs use their own file descriptor management,	4217	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.	4218	in which case they can provide this function to map fds to socket handles.
		4219
		4220	=item EV_WIN32_HANDLE_TO_FD(handle)
		4221
		4222	If C<EV_SELECT_IS_WINSOCKET> then libev maps handles to file descriptors
		4223	using the standard C<_open_osfhandle> function. For programs implementing
		4224	their own fd to handle mapping, overwriting this function makes it easier
		4225	to do so. This can be done by defining this macro to an appropriate value.
		4226
		4227	=item EV_WIN32_CLOSE_FD(fd)
		4228
		4229	If programs implement their own fd to handle mapping on win32, then this
		4230	macro can be used to override the C<close> function, useful to unregister
		4231	file descriptors again. Note that the replacement function has to close
		4232	the underlying OS handle.
3582		4233
3583	=item EV_USE_POLL	4234	=item EV_USE_POLL
3584		4235
3585	If defined to be C<1>, libev will compile in support for the C<poll>(2)	4236	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	4237	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.	4284	as well as for signal and thread safety in C<ev_async> watchers.
3634		4285
3635	In the absence of this define, libev will use C<sig_atomic_t volatile>	4286	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.	4287	(from F<signal.h>), which is usually good enough on most platforms.
3637		4288
3638	=item EV_H	4289	=item EV_H (h)
3639		4290
3640	The name of the F<ev.h> header file used to include it. The default if	4291	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	4292	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.	4293	used to virtually rename the F<ev.h> header file in case of conflicts.
3643		4294
3644	=item EV_CONFIG_H	4295	=item EV_CONFIG_H (h)
3645		4296
3646	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override	4297	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	4298	F<ev.c>'s idea of where to find the F<config.h> file, similarly to
3648	C<EV_H>, above.	4299	C<EV_H>, above.
3649		4300
3650	=item EV_EVENT_H	4301	=item EV_EVENT_H (h)
3651		4302
3652	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea	4303	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">.	4304	of how the F<event.h> header can be found, the default is C<"event.h">.
3654		4305
3655	=item EV_PROTOTYPES	4306	=item EV_PROTOTYPES (h)
3656		4307
3657	If defined to be C<0>, then F<ev.h> will not define any function	4308	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	4309	prototypes, but still define all the structs and other symbols. This is
3659	occasionally useful if you want to provide your own wrapper functions	4310	occasionally useful if you want to provide your own wrapper functions
3660	around libev functions.	4311	around libev functions.
…		…
3682	fine.	4333	fine.
3683		4334
3684	If your embedding application does not need any priorities, defining these	4335	If your embedding application does not need any priorities, defining these
3685	both to C<0> will save some memory and CPU.	4336	both to C<0> will save some memory and CPU.
3686		4337
3687	=item EV_PERIODIC_ENABLE	4338	=item EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE,
		4339	EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE,
		4340	EV_ASYNC_ENABLE, EV_CHILD_ENABLE.
3688		4341
3689	If undefined or defined to be C<1>, then periodic timers are supported. If	4342	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	4343	the respective watcher type is supported. If defined to be C<0>, then it
3691	code.	4344	is not. Disabling watcher types mainly saves code size.
3692		4345
3693	=item EV_IDLE_ENABLE	4346	=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		4347
3722	If you need to shave off some kilobytes of code at the expense of some	4348	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	4349	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	4350	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	4351	that can be enabled on the platform.
3726	the default 4-heap.
3727		4352
3728	You can save even more by disabling watcher types you do not need	4353	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>	4354	with some broad features you want) and then selectively re-enable
3730	(C<-DNDEBUG>) will usually reduce code size a lot.	4355	additional parts you want, for example if you want everything minimal,
		4356	but multiple event loop support, async and child watchers and the poll
		4357	backend, use this:
3731		4358
3732	Defining C<EV_MINIMAL> to C<2> will additionally reduce the core API to	4359	#define EV_FEATURES 0
3733	provide a bare-bones event library. See C<ev.h> for details on what parts	4360	#define EV_MULTIPLICITY 1
3734	of the API are still available, and do not complain if this subset changes	4361	#define EV_USE_POLL 1
3735	over time.	4362	#define EV_CHILD_ENABLE 1
		4363	#define EV_ASYNC_ENABLE 1
		4364
		4365	The actual value is a bitset, it can be a combination of the following
		4366	values:
		4367
		4368	=over 4
		4369
		4370	=item C<1> - faster/larger code
		4371
		4372	Use larger code to speed up some operations.
		4373
		4374	Currently this is used to override some inlining decisions (enlarging the
		4375	code size by roughly 30% on amd64).
		4376
		4377	When optimising for size, use of compiler flags such as C<-Os> with
		4378	gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of
		4379	assertions.
		4380
		4381	=item C<2> - faster/larger data structures
		4382
		4383	Replaces the small 2-heap for timer management by a faster 4-heap, larger
		4384	hash table sizes and so on. This will usually further increase code size
		4385	and can additionally have an effect on the size of data structures at
		4386	runtime.
		4387
		4388	=item C<4> - full API configuration
		4389
		4390	This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and
		4391	enables multiplicity (C<EV_MULTIPLICITY>=1).
		4392
		4393	=item C<8> - full API
		4394
		4395	This enables a lot of the "lesser used" API functions. See C<ev.h> for
		4396	details on which parts of the API are still available without this
		4397	feature, and do not complain if this subset changes over time.
		4398
		4399	=item C<16> - enable all optional watcher types
		4400
		4401	Enables all optional watcher types. If you want to selectively enable
		4402	only some watcher types other than I/O and timers (e.g. prepare,
		4403	embed, async, child...) you can enable them manually by defining
		4404	C<EV_watchertype_ENABLE> to C<1> instead.
		4405
		4406	=item C<32> - enable all backends
		4407
		4408	This enables all backends - without this feature, you need to enable at
		4409	least one backend manually (C<EV_USE_SELECT> is a good choice).
		4410
		4411	=item C<64> - enable OS-specific "helper" APIs
		4412
		4413	Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by
		4414	default.
		4415
		4416	=back
		4417
		4418	Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0>
		4419	reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb
		4420	code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O
		4421	watchers, timers and monotonic clock support.
		4422
		4423	With an intelligent-enough linker (gcc+binutils are intelligent enough
		4424	when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by
		4425	your program might be left out as well - a binary starting a timer and an
		4426	I/O watcher then might come out at only 5Kb.
		4427
		4428	=item EV_AVOID_STDIO
		4429
		4430	If this is set to C<1> at compiletime, then libev will avoid using stdio
		4431	functions (printf, scanf, perror etc.). This will increase the code size
		4432	somewhat, but if your program doesn't otherwise depend on stdio and your
		4433	libc allows it, this avoids linking in the stdio library which is quite
		4434	big.
		4435
		4436	Note that error messages might become less precise when this option is
		4437	enabled.
		4438
		4439	=item EV_NSIG
		4440
		4441	The highest supported signal number, +1 (or, the number of
		4442	signals): Normally, libev tries to deduce the maximum number of signals
		4443	automatically, but sometimes this fails, in which case it can be
		4444	specified. Also, using a lower number than detected (C<32> should be
		4445	good for about any system in existence) can save some memory, as libev
		4446	statically allocates some 12-24 bytes per signal number.
3736		4447
3737	=item EV_PID_HASHSIZE	4448	=item EV_PID_HASHSIZE
3738		4449
3739	C<ev_child> watchers use a small hash table to distribute workload by	4450	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	4451	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	4452	usually more than enough. If you need to manage thousands of children you
3742	increase this value (I<must> be a power of two).	4453	might want to increase this value (I<must> be a power of two).
3743		4454
3744	=item EV_INOTIFY_HASHSIZE	4455	=item EV_INOTIFY_HASHSIZE
3745		4456
3746	C<ev_stat> watchers use a small hash table to distribute workload by	4457	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>),	4458	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>	4459	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	4460	C<ev_stat> watchers you might want to increase this value (I<must> be a
3750	two).	4461	power of two).
3751		4462
3752	=item EV_USE_4HEAP	4463	=item EV_USE_4HEAP
3753		4464
3754	Heaps are not very cache-efficient. To improve the cache-efficiency of the	4465	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	4466	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	4467	to C<1>. The 4-heap uses more complicated (longer) code but has noticeably
3757	faster performance with many (thousands) of watchers.	4468	faster performance with many (thousands) of watchers.
3758		4469
3759	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>	4470	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3760	(disabled).	4471	will be C<0>.
3761		4472
3762	=item EV_HEAP_CACHE_AT	4473	=item EV_HEAP_CACHE_AT
3763		4474
3764	Heaps are not very cache-efficient. To improve the cache-efficiency of the	4475	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	4476	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>),	4477	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,	4478	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	4479	but avoids random read accesses on heap changes. This improves performance
3769	noticeably with many (hundreds) of watchers.	4480	noticeably with many (hundreds) of watchers.
3770		4481
3771	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>	4482	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3772	(disabled).	4483	will be C<0>.
3773		4484
3774	=item EV_VERIFY	4485	=item EV_VERIFY
3775		4486
3776	Controls how much internal verification (see C<ev_loop_verify ()>) will	4487	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	4488	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	4489	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	4490	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	4491	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	4492	verification code will be called very frequently, which will slow down
3782	libev considerably.	4493	libev considerably.
3783		4494
3784	The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be	4495	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3785	C<0>.	4496	will be C<0>.
3786		4497
3787	=item EV_COMMON	4498	=item EV_COMMON
3788		4499
3789	By default, all watchers have a C<void *data> member. By redefining	4500	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	4501	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,	4502	members. You have to define it each time you include one of the files,
3792	though, and it must be identical each time.	4503	though, and it must be identical each time.
3793		4504
3794	For example, the perl EV module uses something like this:	4505	For example, the perl EV module uses something like this:
3795		4506
…		…
3848	file.	4559	file.
3849		4560
3850	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	4561	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:	4562	that everybody includes and which overrides some configure choices:
3852		4563
3853	#define EV_MINIMAL 1	4564	#define EV_FEATURES 8
3854	#define EV_USE_POLL 0	4565	#define EV_USE_SELECT 1
3855	#define EV_MULTIPLICITY 0
3856	#define EV_PERIODIC_ENABLE 0	4566	#define EV_PREPARE_ENABLE 1
		4567	#define EV_IDLE_ENABLE 1
3857	#define EV_STAT_ENABLE 0	4568	#define EV_SIGNAL_ENABLE 1
3858	#define EV_FORK_ENABLE 0	4569	#define EV_CHILD_ENABLE 1
		4570	#define EV_USE_STDEXCEPT 0
3859	#define EV_CONFIG_H <config.h>	4571	#define EV_CONFIG_H <config.h>
3860	#define EV_MINPRI 0
3861	#define EV_MAXPRI 0
3862		4572
3863	#include "ev++.h"	4573	#include "ev++.h"
3864		4574
3865	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	4575	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
3866		4576
…		…
3926	default loop and triggering an C<ev_async> watcher from the default loop	4636	default loop and triggering an C<ev_async> watcher from the default loop
3927	watcher callback into the event loop interested in the signal.	4637	watcher callback into the event loop interested in the signal.
3928		4638
3929	=back	4639	=back
3930		4640
3931	=head4 THREAD LOCKING EXAMPLE	4641	See also L<Thread locking example>.
3932		4642
3933	=head3 COROUTINES	4643	=head3 COROUTINES
3934		4644
3935	Libev is very accommodating to coroutines ("cooperative threads"):	4645	Libev is very accommodating to coroutines ("cooperative threads"):
3936	libev fully supports nesting calls to its functions from different	4646	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	4647	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	4648	different coroutines, and switch freely between both coroutines running
3939	loop, as long as you don't confuse yourself). The only exception is that	4649	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.	4650	that you must not do this from C<ev_periodic> reschedule callbacks.
3941		4651
3942	Care has been taken to ensure that libev does not keep local state inside	4652	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	4653	C<ev_run>, and other calls do not usually allow for coroutine switches as
3944	they do not call any callbacks.	4654	they do not call any callbacks.
3945		4655
3946	=head2 COMPILER WARNINGS	4656	=head2 COMPILER WARNINGS
3947		4657
3948	Depending on your compiler and compiler settings, you might get no or a	4658	Depending on your compiler and compiler settings, you might get no or a
…		…
3959	maintainable.	4669	maintainable.
3960		4670
3961	And of course, some compiler warnings are just plain stupid, or simply	4671	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	4672	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	4673	seems to warn about). For example, certain older gcc versions had some
3964	warnings that resulted an extreme number of false positives. These have	4674	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	4675	been fixed, but some people still insist on making code warn-free with
3966	such buggy versions.	4676	such buggy versions.
3967		4677
3968	While libev is written to generate as few warnings as possible,	4678	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	4679	"warn-free" code is not a goal, and it is recommended not to build libev
…		…
4005	I suggest using suppression lists.	4715	I suggest using suppression lists.
4006		4716
4007		4717
4008	=head1 PORTABILITY NOTES	4718	=head1 PORTABILITY NOTES
4009		4719
		4720	=head2 GNU/LINUX 32 BIT LIMITATIONS
		4721
		4722	GNU/Linux is the only common platform that supports 64 bit file/large file
		4723	interfaces but I<disables> them by default.
		4724
		4725	That means that libev compiled in the default environment doesn't support
		4726	files larger than 2GiB or so, which mainly affects C<ev_stat> watchers.
		4727
		4728	Unfortunately, many programs try to work around this GNU/Linux issue
		4729	by enabling the large file API, which makes them incompatible with the
		4730	standard libev compiled for their system.
		4731
		4732	Likewise, libev cannot enable the large file API itself as this would
		4733	suddenly make it incompatible to the default compile time environment,
		4734	i.e. all programs not using special compile switches.
		4735
		4736	=head2 OS/X AND DARWIN BUGS
		4737
		4738	The whole thing is a bug if you ask me - basically any system interface
		4739	you touch is broken, whether it is locales, poll, kqueue or even the
		4740	OpenGL drivers.
		4741
		4742	=head3 C<kqueue> is buggy
		4743
		4744	The kqueue syscall is broken in all known versions - most versions support
		4745	only sockets, many support pipes.
		4746
		4747	Libev tries to work around this by not using C<kqueue> by default on this
		4748	rotten platform, but of course you can still ask for it when creating a
		4749	loop - embedding a socket-only kqueue loop into a select-based one is
		4750	probably going to work well.
		4751
		4752	=head3 C<poll> is buggy
		4753
		4754	Instead of fixing C<kqueue>, Apple replaced their (working) C<poll>
		4755	implementation by something calling C<kqueue> internally around the 10.5.6
		4756	release, so now C<kqueue> I<and> C<poll> are broken.
		4757
		4758	Libev tries to work around this by not using C<poll> by default on
		4759	this rotten platform, but of course you can still ask for it when creating
		4760	a loop.
		4761
		4762	=head3 C<select> is buggy
		4763
		4764	All that's left is C<select>, and of course Apple found a way to fuck this
		4765	one up as well: On OS/X, C<select> actively limits the number of file
		4766	descriptors you can pass in to 1024 - your program suddenly crashes when
		4767	you use more.
		4768
		4769	There is an undocumented "workaround" for this - defining
		4770	C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should>
		4771	work on OS/X.
		4772
		4773	=head2 SOLARIS PROBLEMS AND WORKAROUNDS
		4774
		4775	=head3 C<errno> reentrancy
		4776
		4777	The default compile environment on Solaris is unfortunately so
		4778	thread-unsafe that you can't even use components/libraries compiled
		4779	without C<-D_REENTRANT> in a threaded program, which, of course, isn't
		4780	defined by default. A valid, if stupid, implementation choice.
		4781
		4782	If you want to use libev in threaded environments you have to make sure
		4783	it's compiled with C<_REENTRANT> defined.
		4784
		4785	=head3 Event port backend
		4786
		4787	The scalable event interface for Solaris is called "event
		4788	ports". Unfortunately, this mechanism is very buggy in all major
		4789	releases. If you run into high CPU usage, your program freezes or you get
		4790	a large number of spurious wakeups, make sure you have all the relevant
		4791	and latest kernel patches applied. No, I don't know which ones, but there
		4792	are multiple ones to apply, and afterwards, event ports actually work
		4793	great.
		4794
		4795	If you can't get it to work, you can try running the program by setting
		4796	the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and
		4797	C<select> backends.
		4798
		4799	=head2 AIX POLL BUG
		4800
		4801	AIX unfortunately has a broken C<poll.h> header. Libev works around
		4802	this by trying to avoid the poll backend altogether (i.e. it's not even
		4803	compiled in), which normally isn't a big problem as C<select> works fine
		4804	with large bitsets on AIX, and AIX is dead anyway.
		4805
4010	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS	4806	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
		4807
		4808	=head3 General issues
4011		4809
4012	Win32 doesn't support any of the standards (e.g. POSIX) that libev	4810	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	4811	requires, and its I/O model is fundamentally incompatible with the POSIX
4014	model. Libev still offers limited functionality on this platform in	4812	model. Libev still offers limited functionality on this platform in
4015	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	4813	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
4016	descriptors. This only applies when using Win32 natively, not when using	4814	descriptors. This only applies when using Win32 natively, not when using
4017	e.g. cygwin.	4815	e.g. cygwin. Actually, it only applies to the microsofts own compilers,
		4816	as every compielr comes with a slightly differently broken/incompatible
		4817	environment.
4018		4818
4019	Lifting these limitations would basically require the full	4819	Lifting these limitations would basically require the full
4020	re-implementation of the I/O system. If you are into these kinds of	4820	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	4821	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).	4822	also that glib is the slowest event library known to man).
4023		4823
4024	There is no supported compilation method available on windows except	4824	There is no supported compilation method available on windows except
4025	embedding it into other applications.	4825	embedding it into other applications.
4026		4826
4027	Sensible signal handling is officially unsupported by Microsoft - libev	4827	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!):	4855	you do I<not> compile the F<ev.c> or any other embedded source files!):
4056		4856
4057	#include "evwrap.h"	4857	#include "evwrap.h"
4058	#include "ev.c"	4858	#include "ev.c"
4059		4859
4060	=over 4
4061
4062	=item The winsocket select function	4860	=head3 The winsocket C<select> function
4063		4861
4064	The winsocket C<select> function doesn't follow POSIX in that it	4862	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	4863	requires socket I<handles> and not socket I<file descriptors> (it is
4066	also extremely buggy). This makes select very inefficient, and also	4864	also extremely buggy). This makes select very inefficient, and also
4067	requires a mapping from file descriptors to socket handles (the Microsoft	4865	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 */	4874	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
4077		4875
4078	Note that winsockets handling of fd sets is O(n), so you can easily get a	4876	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.	4877	complexity in the O(n²) range when using win32.
4080		4878
4081	=item Limited number of file descriptors	4879	=head3 Limited number of file descriptors
4082		4880
4083	Windows has numerous arbitrary (and low) limits on things.	4881	Windows has numerous arbitrary (and low) limits on things.
4084		4882
4085	Early versions of winsocket's select only supported waiting for a maximum	4883	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	4884	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	4899	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,	4900	(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	4901	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.	4902	the cost of calling select (O(n²)) will likely make this unworkable.
4105		4903
4106	=back
4107
4108	=head2 PORTABILITY REQUIREMENTS	4904	=head2 PORTABILITY REQUIREMENTS
4109		4905
4110	In addition to a working ISO-C implementation and of course the	4906	In addition to a working ISO-C implementation and of course the
4111	backend-specific APIs, libev relies on a few additional extensions:	4907	backend-specific APIs, libev relies on a few additional extensions:
4112		4908
…		…
4118	Libev assumes not only that all watcher pointers have the same internal	4914	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	4915	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	4916	assumes that the same (machine) code can be used to call any watcher
4121	callback: The watcher callbacks have different type signatures, but libev	4917	callback: The watcher callbacks have different type signatures, but libev
4122	calls them using an C<ev_watcher *> internally.	4918	calls them using an C<ev_watcher *> internally.
		4919
		4920	=item pointer accesses must be thread-atomic
		4921
		4922	Accessing a pointer value must be atomic, it must both be readable and
		4923	writable in one piece - this is the case on all current architectures.
4123		4924
4124	=item C<sig_atomic_t volatile> must be thread-atomic as well	4925	=item C<sig_atomic_t volatile> must be thread-atomic as well
4125		4926
4126	The type C<sig_atomic_t volatile> (or whatever is defined as	4927	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	4928	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different
…		…
4150	watchers.	4951	watchers.
4151		4952
4152	=item C<double> must hold a time value in seconds with enough accuracy	4953	=item C<double> must hold a time value in seconds with enough accuracy
4153		4954
4154	The type C<double> is used to represent timestamps. It is required to	4955	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	4956	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	4957	good enough for at least into the year 4000 with millisecond accuracy
		4958	(the design goal for libev). This requirement is overfulfilled by
4157	implementations implementing IEEE 754, which is basically all existing	4959	implementations using IEEE 754, which is basically all existing ones. With
4158	ones. With IEEE 754 doubles, you get microsecond accuracy until at least	4960	IEEE 754 doubles, you get microsecond accuracy until at least 2200.
4159	2200.
4160		4961
4161	=back	4962	=back
4162		4963
4163	If you know of other additional requirements drop me a note.	4964	If you know of other additional requirements drop me a note.
4164		4965
…		…
4232	involves iterating over all running async watchers or all signal numbers.	5033	involves iterating over all running async watchers or all signal numbers.
4233		5034
4234	=back	5035	=back
4235		5036
4236		5037
		5038	=head1 PORTING FROM LIBEV 3.X TO 4.X
		5039
		5040	The major version 4 introduced some incompatible changes to the API.
		5041
		5042	At the moment, the C<ev.h> header file provides compatibility definitions
		5043	for all changes, so most programs should still compile. The compatibility
		5044	layer might be removed in later versions of libev, so better update to the
		5045	new API early than late.
		5046
		5047	=over 4
		5048
		5049	=item C<EV_COMPAT3> backwards compatibility mechanism
		5050
		5051	The backward compatibility mechanism can be controlled by
		5052	C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING>
		5053	section.
		5054
		5055	=item C<ev_default_destroy> and C<ev_default_fork> have been removed
		5056
		5057	These calls can be replaced easily by their C<ev_loop_xxx> counterparts:
		5058
		5059	ev_loop_destroy (EV_DEFAULT_UC);
		5060	ev_loop_fork (EV_DEFAULT);
		5061
		5062	=item function/symbol renames
		5063
		5064	A number of functions and symbols have been renamed:
		5065
		5066	ev_loop => ev_run
		5067	EVLOOP_NONBLOCK => EVRUN_NOWAIT
		5068	EVLOOP_ONESHOT => EVRUN_ONCE
		5069
		5070	ev_unloop => ev_break
		5071	EVUNLOOP_CANCEL => EVBREAK_CANCEL
		5072	EVUNLOOP_ONE => EVBREAK_ONE
		5073	EVUNLOOP_ALL => EVBREAK_ALL
		5074
		5075	EV_TIMEOUT => EV_TIMER
		5076
		5077	ev_loop_count => ev_iteration
		5078	ev_loop_depth => ev_depth
		5079	ev_loop_verify => ev_verify
		5080
		5081	Most functions working on C<struct ev_loop> objects don't have an
		5082	C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and
		5083	associated constants have been renamed to not collide with the C<struct
		5084	ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme
		5085	as all other watcher types. Note that C<ev_loop_fork> is still called
		5086	C<ev_loop_fork> because it would otherwise clash with the C<ev_fork>
		5087	typedef.
		5088
		5089	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>
		5090
		5091	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different
		5092	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile
		5093	and work, but the library code will of course be larger.
		5094
		5095	=back
		5096
		5097
4237	=head1 GLOSSARY	5098	=head1 GLOSSARY
4238		5099
4239	=over 4	5100	=over 4
4240		5101
4241	=item active	5102	=item active
4242		5103
4243	A watcher is active as long as it has been started (has been attached to	5104	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).	5105	See L<WATCHER STATES> for details.
4245		5106
4246	=item application	5107	=item application
4247		5108
4248	In this document, an application is whatever is using libev.	5109	In this document, an application is whatever is using libev.
		5110
		5111	=item backend
		5112
		5113	The part of the code dealing with the operating system interfaces.
4249		5114
4250	=item callback	5115	=item callback
4251		5116
4252	The address of a function that is called when some event has been	5117	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	5118	detected. Callbacks are being passed the event loop, the watcher that
4254	received the event, and the actual event bitset.	5119	received the event, and the actual event bitset.
4255		5120
4256	=item callback invocation	5121	=item callback/watcher invocation
4257		5122
4258	The act of calling the callback associated with a watcher.	5123	The act of calling the callback associated with a watcher.
4259		5124
4260	=item event	5125	=item event
4261		5126
4262	A change of state of some external event, such as data now being available	5127	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	5128	for reading on a file descriptor, time having passed or simply not having
4264	any other events happening anymore.	5129	any other events happening anymore.
4265		5130
4266	In libev, events are represented as single bits (such as C<EV_READ> or	5131	In libev, events are represented as single bits (such as C<EV_READ> or
4267	C<EV_TIMEOUT>).	5132	C<EV_TIMER>).
4268		5133
4269	=item event library	5134	=item event library
4270		5135
4271	A software package implementing an event model and loop.	5136	A software package implementing an event model and loop.
4272		5137
…		…
4280	The model used to describe how an event loop handles and processes	5145	The model used to describe how an event loop handles and processes
4281	watchers and events.	5146	watchers and events.
4282		5147
4283	=item pending	5148	=item pending
4284		5149
4285	A watcher is pending as soon as the corresponding event has been detected,	5150	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	5151	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		5152
4292	=item real time	5153	=item real time
4293		5154
4294	The physical time that is observed. It is apparently strictly monotonic :)	5155	The physical time that is observed. It is apparently strictly monotonic :)
4295		5156
…		…
4302	=item watcher	5163	=item watcher
4303		5164
4304	A data structure that describes interest in certain events. Watchers need	5165	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.	5166	to be started (attached to an event loop) before they can receive events.
4306		5167
4307	=item watcher invocation
4308
4309	The act of calling the callback associated with a watcher.
4310
4311	=back	5168	=back
4312		5169
4313	=head1 AUTHOR	5170	=head1 AUTHOR
4314		5171
4315	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson.	5172	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael
		5173	Magnusson and Emanuele Giaquinta.
4316		5174

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