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		1	=encoding utf-8
		2
1	=head1 NAME	3	=head1 NAME
2		4
3	libev - a high performance full-featured event loop written in C	5	libev - a high performance full-featured event loop written in C
4		6
5	=head1 SYNOPSIS	7	=head1 SYNOPSIS
…		…
26	puts ("stdin ready");	28	puts ("stdin ready");
27	// for one-shot events, one must manually stop the watcher	29	// for one-shot events, one must manually stop the watcher
28	// with its corresponding stop function.	30	// with its corresponding stop function.
29	ev_io_stop (EV_A_ w);	31	ev_io_stop (EV_A_ w);
30		32
31	// this causes all nested ev_loop's to stop iterating	33	// this causes all nested ev_run's to stop iterating
32	ev_unloop (EV_A_ EVUNLOOP_ALL);	34	ev_break (EV_A_ EVBREAK_ALL);
33	}	35	}
34		36
35	// another callback, this time for a time-out	37	// another callback, this time for a time-out
36	static void	38	static void
37	timeout_cb (EV_P_ ev_timer *w, int revents)	39	timeout_cb (EV_P_ ev_timer *w, int revents)
38	{	40	{
39	puts ("timeout");	41	puts ("timeout");
40	// this causes the innermost ev_loop to stop iterating	42	// this causes the innermost ev_run to stop iterating
41	ev_unloop (EV_A_ EVUNLOOP_ONE);	43	ev_break (EV_A_ EVBREAK_ONE);
42	}	44	}
43		45
44	int	46	int
45	main (void)	47	main (void)
46	{	48	{
47	// use the default event loop unless you have special needs	49	// use the default event loop unless you have special needs
48	struct ev_loop *loop = ev_default_loop (0);	50	struct ev_loop *loop = EV_DEFAULT;
49		51
50	// initialise an io watcher, then start it	52	// initialise an io watcher, then start it
51	// this one will watch for stdin to become readable	53	// this one will watch for stdin to become readable
52	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);	54	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);
53	ev_io_start (loop, &stdin_watcher);	55	ev_io_start (loop, &stdin_watcher);
…		…
56	// simple non-repeating 5.5 second timeout	58	// simple non-repeating 5.5 second timeout
57	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);	59	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
58	ev_timer_start (loop, &timeout_watcher);	60	ev_timer_start (loop, &timeout_watcher);
59		61
60	// now wait for events to arrive	62	// now wait for events to arrive
61	ev_loop (loop, 0);	63	ev_run (loop, 0);
62		64
63	// unloop was called, so exit	65	// break was called, so exit
64	return 0;	66	return 0;
65	}	67	}
66		68
67	=head1 ABOUT THIS DOCUMENT	69	=head1 ABOUT THIS DOCUMENT
68		70
…		…
77	on event-based programming, nor will it introduce event-based programming	79	on event-based programming, nor will it introduce event-based programming
78	with libev.	80	with libev.
79		81
80	Familiarity with event based programming techniques in general is assumed	82	Familiarity with event based programming techniques in general is assumed
81	throughout this document.	83	throughout this document.
		84
		85	=head1 WHAT TO READ WHEN IN A HURRY
		86
		87	This manual tries to be very detailed, but unfortunately, this also makes
		88	it very long. If you just want to know the basics of libev, I suggest
		89	reading L</ANATOMY OF A WATCHER>, then the L</EXAMPLE PROGRAM> above and
		90	look up the missing functions in L</GLOBAL FUNCTIONS> and the C<ev_io> and
		91	C<ev_timer> sections in L</WATCHER TYPES>.
82		92
83	=head1 ABOUT LIBEV	93	=head1 ABOUT LIBEV
84		94
85	Libev is an event loop: you register interest in certain events (such as a	95	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	96	file descriptor being readable or a timeout occurring), and it will manage
…		…
124	this argument.	134	this argument.
125		135
126	=head2 TIME REPRESENTATION	136	=head2 TIME REPRESENTATION
127		137
128	Libev represents time as a single floating point number, representing	138	Libev represents time as a single floating point number, representing
129	the (fractional) number of seconds since the (POSIX) epoch (in practise	139	the (fractional) number of seconds since the (POSIX) epoch (in practice
130	somewhere near the beginning of 1970, details are complicated, don't	140	somewhere near the beginning of 1970, details are complicated, don't
131	ask). This type is called C<ev_tstamp>, which is what you should use	141	ask). This type is called C<ev_tstamp>, which is what you should use
132	too. It usually aliases to the C<double> type in C. When you need to do	142	too. It usually aliases to the C<double> type in C. When you need to do
133	any calculations on it, you should treat it as some floating point value.	143	any calculations on it, you should treat it as some floating point value.
134		144
…		…
165		175
166	=item ev_tstamp ev_time ()	176	=item ev_tstamp ev_time ()
167		177
168	Returns the current time as libev would use it. Please note that the	178	Returns the current time as libev would use it. Please note that the
169	C<ev_now> function is usually faster and also often returns the timestamp	179	C<ev_now> function is usually faster and also often returns the timestamp
170	you actually want to know.	180	you actually want to know. Also interesting is the combination of
		181	C<ev_now_update> and C<ev_now>.
171		182
172	=item ev_sleep (ev_tstamp interval)	183	=item ev_sleep (ev_tstamp interval)
173		184
174	Sleep for the given interval: The current thread will be blocked until	185	Sleep for the given interval: The current thread will be blocked
175	either it is interrupted or the given time interval has passed. Basically	186	until either it is interrupted or the given time interval has
		187	passed (approximately - it might return a bit earlier even if not
		188	interrupted). Returns immediately if C<< interval <= 0 >>.
		189
176	this is a sub-second-resolution C<sleep ()>.	190	Basically this is a sub-second-resolution C<sleep ()>.
		191
		192	The range of the C<interval> is limited - libev only guarantees to work
		193	with sleep times of up to one day (C<< interval <= 86400 >>).
177		194
178	=item int ev_version_major ()	195	=item int ev_version_major ()
179		196
180	=item int ev_version_minor ()	197	=item int ev_version_minor ()
181		198
…		…
192	as this indicates an incompatible change. Minor versions are usually	209	as this indicates an incompatible change. Minor versions are usually
193	compatible to older versions, so a larger minor version alone is usually	210	compatible to older versions, so a larger minor version alone is usually
194	not a problem.	211	not a problem.
195		212
196	Example: Make sure we haven't accidentally been linked against the wrong	213	Example: Make sure we haven't accidentally been linked against the wrong
197	version (note, however, that this will not detect ABI mismatches :).	214	version (note, however, that this will not detect other ABI mismatches,
		215	such as LFS or reentrancy).
198		216
199	assert (("libev version mismatch",	217	assert (("libev version mismatch",
200	ev_version_major () == EV_VERSION_MAJOR	218	ev_version_major () == EV_VERSION_MAJOR
201	&& ev_version_minor () >= EV_VERSION_MINOR));	219	&& ev_version_minor () >= EV_VERSION_MINOR));
202		220
…		…
213	assert (("sorry, no epoll, no sex",	231	assert (("sorry, no epoll, no sex",
214	ev_supported_backends () & EVBACKEND_EPOLL));	232	ev_supported_backends () & EVBACKEND_EPOLL));
215		233
216	=item unsigned int ev_recommended_backends ()	234	=item unsigned int ev_recommended_backends ()
217		235
218	Return the set of all backends compiled into this binary of libev and also	236	Return the set of all backends compiled into this binary of libev and
219	recommended for this platform. This set is often smaller than the one	237	also recommended for this platform, meaning it will work for most file
		238	descriptor types. This set is often smaller than the one returned by
220	returned by C<ev_supported_backends>, as for example kqueue is broken on	239	C<ev_supported_backends>, as for example kqueue is broken on most BSDs
221	most BSDs and will not be auto-detected unless you explicitly request it	240	and will not be auto-detected unless you explicitly request it (assuming
222	(assuming you know what you are doing). This is the set of backends that	241	you know what you are doing). This is the set of backends that libev will
223	libev will probe for if you specify no backends explicitly.	242	probe for if you specify no backends explicitly.
224		243
225	=item unsigned int ev_embeddable_backends ()	244	=item unsigned int ev_embeddable_backends ()
226		245
227	Returns the set of backends that are embeddable in other event loops. This	246	Returns the set of backends that are embeddable in other event loops. This
228	is the theoretical, all-platform, value. To find which backends	247	value is platform-specific but can include backends not available on the
229	might be supported on the current system, you would need to look at	248	current system. To find which embeddable backends might be supported on
230	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for	249	the current system, you would need to look at C<ev_embeddable_backends ()
231	recommended ones.	250	& ev_supported_backends ()>, likewise for recommended ones.
232		251
233	See the description of C<ev_embed> watchers for more info.	252	See the description of C<ev_embed> watchers for more info.
234		253
235	=item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT]	254	=item ev_set_allocator (void *(*cb)(void *ptr, long size) throw ())
236		255
237	Sets the allocation function to use (the prototype is similar - the	256	Sets the allocation function to use (the prototype is similar - the
238	semantics are identical to the C<realloc> C89/SuS/POSIX function). It is	257	semantics are identical to the C<realloc> C89/SuS/POSIX function). It is
239	used to allocate and free memory (no surprises here). If it returns zero	258	used to allocate and free memory (no surprises here). If it returns zero
240	when memory needs to be allocated (C<size != 0>), the library might abort	259	when memory needs to be allocated (C<size != 0>), the library might abort
…		…
246		265
247	You could override this function in high-availability programs to, say,	266	You could override this function in high-availability programs to, say,
248	free some memory if it cannot allocate memory, to use a special allocator,	267	free some memory if it cannot allocate memory, to use a special allocator,
249	or even to sleep a while and retry until some memory is available.	268	or even to sleep a while and retry until some memory is available.
250		269
		270	Example: The following is the C<realloc> function that libev itself uses
		271	which should work with C<realloc> and C<free> functions of all kinds and
		272	is probably a good basis for your own implementation.
		273
		274	static void *
		275	ev_realloc_emul (void *ptr, long size) EV_NOEXCEPT
		276	{
		277	if (size)
		278	return realloc (ptr, size);
		279
		280	free (ptr);
		281	return 0;
		282	}
		283
251	Example: Replace the libev allocator with one that waits a bit and then	284	Example: Replace the libev allocator with one that waits a bit and then
252	retries (example requires a standards-compliant C<realloc>).	285	retries.
253		286
254	static void *	287	static void *
255	persistent_realloc (void *ptr, size_t size)	288	persistent_realloc (void *ptr, size_t size)
256	{	289	{
		290	if (!size)
		291	{
		292	free (ptr);
		293	return 0;
		294	}
		295
257	for (;;)	296	for (;;)
258	{	297	{
259	void *newptr = realloc (ptr, size);	298	void *newptr = realloc (ptr, size);
260		299
261	if (newptr)	300	if (newptr)
…		…
266	}	305	}
267		306
268	...	307	...
269	ev_set_allocator (persistent_realloc);	308	ev_set_allocator (persistent_realloc);
270		309
271	=item ev_set_syserr_cb (void (*cb)(const char *msg)); [NOT REENTRANT]	310	=item ev_set_syserr_cb (void (*cb)(const char *msg) throw ())
272		311
273	Set the callback function to call on a retryable system call error (such	312	Set the callback function to call on a retryable system call error (such
274	as failed select, poll, epoll_wait). The message is a printable string	313	as failed select, poll, epoll_wait). The message is a printable string
275	indicating the system call or subsystem causing the problem. If this	314	indicating the system call or subsystem causing the problem. If this
276	callback is set, then libev will expect it to remedy the situation, no	315	callback is set, then libev will expect it to remedy the situation, no
…		…
288	}	327	}
289		328
290	...	329	...
291	ev_set_syserr_cb (fatal_error);	330	ev_set_syserr_cb (fatal_error);
292		331
		332	=item ev_feed_signal (int signum)
		333
		334	This function can be used to "simulate" a signal receive. It is completely
		335	safe to call this function at any time, from any context, including signal
		336	handlers or random threads.
		337
		338	Its main use is to customise signal handling in your process, especially
		339	in the presence of threads. For example, you could block signals
		340	by default in all threads (and specifying C<EVFLAG_NOSIGMASK> when
		341	creating any loops), and in one thread, use C<sigwait> or any other
		342	mechanism to wait for signals, then "deliver" them to libev by calling
		343	C<ev_feed_signal>.
		344
293	=back	345	=back
294		346
295	=head1 FUNCTIONS CONTROLLING THE EVENT LOOP	347	=head1 FUNCTIONS CONTROLLING EVENT LOOPS
296		348
297	An event loop is described by a C<struct ev_loop *> (the C<struct>	349	An event loop is described by a C<struct ev_loop *> (the C<struct> is
298	is I<not> optional in this case, as there is also an C<ev_loop>	350	I<not> optional in this case unless libev 3 compatibility is disabled, as
299	I<function>).	351	libev 3 had an C<ev_loop> function colliding with the struct name).
300		352
301	The library knows two types of such loops, the I<default> loop, which	353	The library knows two types of such loops, the I<default> loop, which
302	supports signals and child events, and dynamically created loops which do	354	supports child process events, and dynamically created event loops which
303	not.	355	do not.
304		356
305	=over 4	357	=over 4
306		358
307	=item struct ev_loop *ev_default_loop (unsigned int flags)	359	=item struct ev_loop *ev_default_loop (unsigned int flags)
308		360
309	This will initialise the default event loop if it hasn't been initialised	361	This returns the "default" event loop object, which is what you should
310	yet and return it. If the default loop could not be initialised, returns	362	normally use when you just need "the event loop". Event loop objects and
311	false. If it already was initialised it simply returns it (and ignores the	363	the C<flags> parameter are described in more detail in the entry for
312	flags. If that is troubling you, check C<ev_backend ()> afterwards).	364	C<ev_loop_new>.
		365
		366	If the default loop is already initialised then this function simply
		367	returns it (and ignores the flags. If that is troubling you, check
		368	C<ev_backend ()> afterwards). Otherwise it will create it with the given
		369	flags, which should almost always be C<0>, unless the caller is also the
		370	one calling C<ev_run> or otherwise qualifies as "the main program".
313		371
314	If you don't know what event loop to use, use the one returned from this	372	If you don't know what event loop to use, use the one returned from this
315	function.	373	function (or via the C<EV_DEFAULT> macro).
316		374
317	Note that this function is I<not> thread-safe, so if you want to use it	375	Note that this function is I<not> thread-safe, so if you want to use it
318	from multiple threads, you have to lock (note also that this is unlikely,	376	from multiple threads, you have to employ some kind of mutex (note also
319	as loops cannot be shared easily between threads anyway).	377	that this case is unlikely, as loops cannot be shared easily between
		378	threads anyway).
320		379
321	The default loop is the only loop that can handle C<ev_signal> and	380	The default loop is the only loop that can handle C<ev_child> watchers,
322	C<ev_child> watchers, and to do this, it always registers a handler	381	and to do this, it always registers a handler for C<SIGCHLD>. If this is
323	for C<SIGCHLD>. If this is a problem for your application you can either	382	a problem for your application you can either create a dynamic loop with
324	create a dynamic loop with C<ev_loop_new> that doesn't do that, or you	383	C<ev_loop_new> which doesn't do that, or you can simply overwrite the
325	can simply overwrite the C<SIGCHLD> signal handler I<after> calling	384	C<SIGCHLD> signal handler I<after> calling C<ev_default_init>.
326	C<ev_default_init>.	385
		386	Example: This is the most typical usage.
		387
		388	if (!ev_default_loop (0))
		389	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
		390
		391	Example: Restrict libev to the select and poll backends, and do not allow
		392	environment settings to be taken into account:
		393
		394	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
		395
		396	=item struct ev_loop *ev_loop_new (unsigned int flags)
		397
		398	This will create and initialise a new event loop object. If the loop
		399	could not be initialised, returns false.
		400
		401	This function is thread-safe, and one common way to use libev with
		402	threads is indeed to create one loop per thread, and using the default
		403	loop in the "main" or "initial" thread.
327		404
328	The flags argument can be used to specify special behaviour or specific	405	The flags argument can be used to specify special behaviour or specific
329	backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>).	406	backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>).
330		407
331	The following flags are supported:	408	The following flags are supported:
…		…
341		418
342	If this flag bit is or'ed into the flag value (or the program runs setuid	419	If this flag bit is or'ed into the flag value (or the program runs setuid
343	or setgid) then libev will I<not> look at the environment variable	420	or setgid) then libev will I<not> look at the environment variable
344	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	421	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
345	override the flags completely if it is found in the environment. This is	422	override the flags completely if it is found in the environment. This is
346	useful to try out specific backends to test their performance, or to work	423	useful to try out specific backends to test their performance, to work
347	around bugs.	424	around bugs, or to make libev threadsafe (accessing environment variables
		425	cannot be done in a threadsafe way, but usually it works if no other
		426	thread modifies them).
348		427
349	=item C<EVFLAG_FORKCHECK>	428	=item C<EVFLAG_FORKCHECK>
350		429
351	Instead of calling C<ev_loop_fork> manually after a fork, you can also	430	Instead of calling C<ev_loop_fork> manually after a fork, you can also
352	make libev check for a fork in each iteration by enabling this flag.	431	make libev check for a fork in each iteration by enabling this flag.
353		432
354	This works by calling C<getpid ()> on every iteration of the loop,	433	This works by calling C<getpid ()> on every iteration of the loop,
355	and thus this might slow down your event loop if you do a lot of loop	434	and thus this might slow down your event loop if you do a lot of loop
356	iterations and little real work, but is usually not noticeable (on my	435	iterations and little real work, but is usually not noticeable (on my
357	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence	436	GNU/Linux system for example, C<getpid> is actually a simple 5-insn
358	without a system call and thus I<very> fast, but my GNU/Linux system also has	437	sequence without a system call and thus I<very> fast, but my GNU/Linux
359	C<pthread_atfork> which is even faster).	438	system also has C<pthread_atfork> which is even faster). (Update: glibc
		439	versions 2.25 apparently removed the C<getpid> optimisation again).
360		440
361	The big advantage of this flag is that you can forget about fork (and	441	The big advantage of this flag is that you can forget about fork (and
362	forget about forgetting to tell libev about forking) when you use this	442	forget about forgetting to tell libev about forking, although you still
363	flag.	443	have to ignore C<SIGPIPE>) when you use this flag.
364		444
365	This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS>	445	This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS>
366	environment variable.	446	environment variable.
367		447
368	=item C<EVFLAG_NOINOTIFY>	448	=item C<EVFLAG_NOINOTIFY>
369		449
370	When this flag is specified, then libev will not attempt to use the	450	When this flag is specified, then libev will not attempt to use the
371	I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and	451	I<inotify> API for its C<ev_stat> watchers. Apart from debugging and
372	testing, this flag can be useful to conserve inotify file descriptors, as	452	testing, this flag can be useful to conserve inotify file descriptors, as
373	otherwise each loop using C<ev_stat> watchers consumes one inotify handle.	453	otherwise each loop using C<ev_stat> watchers consumes one inotify handle.
374		454
375	=item C<EVFLAG_SIGNALFD>	455	=item C<EVFLAG_SIGNALFD>
376		456
377	When this flag is specified, then libev will attempt to use the	457	When this flag is specified, then libev will attempt to use the
378	I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This API	458	I<signalfd> API for its C<ev_signal> (and C<ev_child>) watchers. This API
379	delivers signals synchronously, which makes it both faster and might make	459	delivers signals synchronously, which makes it both faster and might make
380	it possible to get the queued signal data. It can also simplify signal	460	it possible to get the queued signal data. It can also simplify signal
381	handling with threads, as long as you properly block signals in your	461	handling with threads, as long as you properly block signals in your
382	threads that are not interested in handling them.	462	threads that are not interested in handling them.
383		463
384	Signalfd will not be used by default as this changes your signal mask, and	464	Signalfd will not be used by default as this changes your signal mask, and
385	there are a lot of shoddy libraries and programs (glib's threadpool for	465	there are a lot of shoddy libraries and programs (glib's threadpool for
386	example) that can't properly initialise their signal masks.	466	example) that can't properly initialise their signal masks.
		467
		468	=item C<EVFLAG_NOSIGMASK>
		469
		470	When this flag is specified, then libev will avoid to modify the signal
		471	mask. Specifically, this means you have to make sure signals are unblocked
		472	when you want to receive them.
		473
		474	This behaviour is useful when you want to do your own signal handling, or
		475	want to handle signals only in specific threads and want to avoid libev
		476	unblocking the signals.
		477
		478	It's also required by POSIX in a threaded program, as libev calls
		479	C<sigprocmask>, whose behaviour is officially unspecified.
		480
		481	This flag's behaviour will become the default in future versions of libev.
387		482
388	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	483	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
389		484
390	This is your standard select(2) backend. Not I<completely> standard, as	485	This is your standard select(2) backend. Not I<completely> standard, as
391	libev tries to roll its own fd_set with no limits on the number of fds,	486	libev tries to roll its own fd_set with no limits on the number of fds,
…		…
419	=item C<EVBACKEND_EPOLL> (value 4, Linux)	514	=item C<EVBACKEND_EPOLL> (value 4, Linux)
420		515
421	Use the linux-specific epoll(7) interface (for both pre- and post-2.6.9	516	Use the linux-specific epoll(7) interface (for both pre- and post-2.6.9
422	kernels).	517	kernels).
423		518
424	For few fds, this backend is a bit little slower than poll and select,	519	For few fds, this backend is a bit little slower than poll and select, but
425	but it scales phenomenally better. While poll and select usually scale	520	it scales phenomenally better. While poll and select usually scale like
426	like O(total_fds) where n is the total number of fds (or the highest fd),	521	O(total_fds) where total_fds is the total number of fds (or the highest
427	epoll scales either O(1) or O(active_fds).	522	fd), epoll scales either O(1) or O(active_fds).
428		523
429	The epoll mechanism deserves honorable mention as the most misdesigned	524	The epoll mechanism deserves honorable mention as the most misdesigned
430	of the more advanced event mechanisms: mere annoyances include silently	525	of the more advanced event mechanisms: mere annoyances include silently
431	dropping file descriptors, requiring a system call per change per file	526	dropping file descriptors, requiring a system call per change per file
432	descriptor (and unnecessary guessing of parameters), problems with dup and	527	descriptor (and unnecessary guessing of parameters), problems with dup,
		528	returning before the timeout value, resulting in additional iterations
		529	(and only giving 5ms accuracy while select on the same platform gives
433	so on. The biggest issue is fork races, however - if a program forks then	530	0.1ms) and so on. The biggest issue is fork races, however - if a program
434	I<both> parent and child process have to recreate the epoll set, which can	531	forks then I<both> parent and child process have to recreate the epoll
435	take considerable time (one syscall per file descriptor) and is of course	532	set, which can take considerable time (one syscall per file descriptor)
436	hard to detect.	533	and is of course hard to detect.
437		534
438	Epoll is also notoriously buggy - embedding epoll fds I<should> work, but	535	Epoll is also notoriously buggy - embedding epoll fds I<should> work,
439	of course I<doesn't>, and epoll just loves to report events for totally	536	but of course I<doesn't>, and epoll just loves to report events for
440	I<different> file descriptors (even already closed ones, so one cannot	537	totally I<different> file descriptors (even already closed ones, so
441	even remove them from the set) than registered in the set (especially	538	one cannot even remove them from the set) than registered in the set
442	on SMP systems). Libev tries to counter these spurious notifications by	539	(especially on SMP systems). Libev tries to counter these spurious
443	employing an additional generation counter and comparing that against the	540	notifications by employing an additional generation counter and comparing
444	events to filter out spurious ones, recreating the set when required. Last	541	that against the events to filter out spurious ones, recreating the set
		542	when required. Epoll also erroneously rounds down timeouts, but gives you
		543	no way to know when and by how much, so sometimes you have to busy-wait
		544	because epoll returns immediately despite a nonzero timeout. And last
445	not least, it also refuses to work with some file descriptors which work	545	not least, it also refuses to work with some file descriptors which work
446	perfectly fine with C<select> (files, many character devices...).	546	perfectly fine with C<select> (files, many character devices...).
		547
		548	Epoll is truly the train wreck among event poll mechanisms, a frankenpoll,
		549	cobbled together in a hurry, no thought to design or interaction with
		550	others. Oh, the pain, will it ever stop...
447		551
448	While stopping, setting and starting an I/O watcher in the same iteration	552	While stopping, setting and starting an I/O watcher in the same iteration
449	will result in some caching, there is still a system call per such	553	will result in some caching, there is still a system call per such
450	incident (because the same I<file descriptor> could point to a different	554	incident (because the same I<file descriptor> could point to a different
451	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed	555	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed
…		…
488		592
489	It scales in the same way as the epoll backend, but the interface to the	593	It scales in the same way as the epoll backend, but the interface to the
490	kernel is more efficient (which says nothing about its actual speed, of	594	kernel is more efficient (which says nothing about its actual speed, of
491	course). While stopping, setting and starting an I/O watcher does never	595	course). While stopping, setting and starting an I/O watcher does never
492	cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to	596	cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to
493	two event changes per incident. Support for C<fork ()> is very bad (but	597	two event changes per incident. Support for C<fork ()> is very bad (you
494	sane, unlike epoll) and it drops fds silently in similarly hard-to-detect	598	might have to leak fd's on fork, but it's more sane than epoll) and it
495	cases	599	drops fds silently in similarly hard-to-detect cases.
496		600
497	This backend usually performs well under most conditions.	601	This backend usually performs well under most conditions.
498		602
499	While nominally embeddable in other event loops, this doesn't work	603	While nominally embeddable in other event loops, this doesn't work
500	everywhere, so you might need to test for this. And since it is broken	604	everywhere, so you might need to test for this. And since it is broken
…		…
517	=item C<EVBACKEND_PORT> (value 32, Solaris 10)	621	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
518		622
519	This uses the Solaris 10 event port mechanism. As with everything on Solaris,	623	This uses the Solaris 10 event port mechanism. As with everything on Solaris,
520	it's really slow, but it still scales very well (O(active_fds)).	624	it's really slow, but it still scales very well (O(active_fds)).
521		625
522	Please note that Solaris event ports can deliver a lot of spurious
523	notifications, so you need to use non-blocking I/O or other means to avoid
524	blocking when no data (or space) is available.
525
526	While this backend scales well, it requires one system call per active	626	While this backend scales well, it requires one system call per active
527	file descriptor per loop iteration. For small and medium numbers of file	627	file descriptor per loop iteration. For small and medium numbers of file
528	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend	628	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend
529	might perform better.	629	might perform better.
530		630
531	On the positive side, with the exception of the spurious readiness	631	On the positive side, this backend actually performed fully to
532	notifications, this backend actually performed fully to specification
533	in all tests and is fully embeddable, which is a rare feat among the	632	specification in all tests and is fully embeddable, which is a rare feat
534	OS-specific backends (I vastly prefer correctness over speed hacks).	633	among the OS-specific backends (I vastly prefer correctness over speed
		634	hacks).
		635
		636	On the negative side, the interface is I<bizarre> - so bizarre that
		637	even sun itself gets it wrong in their code examples: The event polling
		638	function sometimes returns events to the caller even though an error
		639	occurred, but with no indication whether it has done so or not (yes, it's
		640	even documented that way) - deadly for edge-triggered interfaces where you
		641	absolutely have to know whether an event occurred or not because you have
		642	to re-arm the watcher.
		643
		644	Fortunately libev seems to be able to work around these idiocies.
535		645
536	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as	646	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as
537	C<EVBACKEND_POLL>.	647	C<EVBACKEND_POLL>.
538		648
539	=item C<EVBACKEND_ALL>	649	=item C<EVBACKEND_ALL>
540		650
541	Try all backends (even potentially broken ones that wouldn't be tried	651	Try all backends (even potentially broken ones that wouldn't be tried
542	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as	652	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as
543	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.	653	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.
544		654
545	It is definitely not recommended to use this flag.	655	It is definitely not recommended to use this flag, use whatever
		656	C<ev_recommended_backends ()> returns, or simply do not specify a backend
		657	at all.
		658
		659	=item C<EVBACKEND_MASK>
		660
		661	Not a backend at all, but a mask to select all backend bits from a
		662	C<flags> value, in case you want to mask out any backends from a flags
		663	value (e.g. when modifying the C<LIBEV_FLAGS> environment variable).
546		664
547	=back	665	=back
548		666
549	If one or more of the backend flags are or'ed into the flags value,	667	If one or more of the backend flags are or'ed into the flags value,
550	then only these backends will be tried (in the reverse order as listed	668	then only these backends will be tried (in the reverse order as listed
551	here). If none are specified, all backends in C<ev_recommended_backends	669	here). If none are specified, all backends in C<ev_recommended_backends
552	()> will be tried.	670	()> will be tried.
553		671
554	Example: This is the most typical usage.
555
556	if (!ev_default_loop (0))
557	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
558
559	Example: Restrict libev to the select and poll backends, and do not allow
560	environment settings to be taken into account:
561
562	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
563
564	Example: Use whatever libev has to offer, but make sure that kqueue is
565	used if available (warning, breaks stuff, best use only with your own
566	private event loop and only if you know the OS supports your types of
567	fds):
568
569	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
570
571	=item struct ev_loop *ev_loop_new (unsigned int flags)
572
573	Similar to C<ev_default_loop>, but always creates a new event loop that is
574	always distinct from the default loop.
575
576	Note that this function I<is> thread-safe, and one common way to use
577	libev with threads is indeed to create one loop per thread, and using the
578	default loop in the "main" or "initial" thread.
579
580	Example: Try to create a event loop that uses epoll and nothing else.	672	Example: Try to create a event loop that uses epoll and nothing else.
581		673
582	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	674	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
583	if (!epoller)	675	if (!epoller)
584	fatal ("no epoll found here, maybe it hides under your chair");	676	fatal ("no epoll found here, maybe it hides under your chair");
585		677
		678	Example: Use whatever libev has to offer, but make sure that kqueue is
		679	used if available.
		680
		681	struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE);
		682
586	=item ev_default_destroy ()	683	=item ev_loop_destroy (loop)
587		684
588	Destroys the default loop (frees all memory and kernel state etc.). None	685	Destroys an event loop object (frees all memory and kernel state
589	of the active event watchers will be stopped in the normal sense, so	686	etc.). None of the active event watchers will be stopped in the normal
590	e.g. C<ev_is_active> might still return true. It is your responsibility to	687	sense, so e.g. C<ev_is_active> might still return true. It is your
591	either stop all watchers cleanly yourself I<before> calling this function,	688	responsibility to either stop all watchers cleanly yourself I<before>
592	or cope with the fact afterwards (which is usually the easiest thing, you	689	calling this function, or cope with the fact afterwards (which is usually
593	can just ignore the watchers and/or C<free ()> them for example).	690	the easiest thing, you can just ignore the watchers and/or C<free ()> them
		691	for example).
594		692
595	Note that certain global state, such as signal state (and installed signal	693	Note that certain global state, such as signal state (and installed signal
596	handlers), will not be freed by this function, and related watchers (such	694	handlers), will not be freed by this function, and related watchers (such
597	as signal and child watchers) would need to be stopped manually.	695	as signal and child watchers) would need to be stopped manually.
598		696
599	In general it is not advisable to call this function except in the	697	This function is normally used on loop objects allocated by
600	rare occasion where you really need to free e.g. the signal handling	698	C<ev_loop_new>, but it can also be used on the default loop returned by
		699	C<ev_default_loop>, in which case it is not thread-safe.
		700
		701	Note that it is not advisable to call this function on the default loop
		702	except in the rare occasion where you really need to free its resources.
601	pipe fds. If you need dynamically allocated loops it is better to use	703	If you need dynamically allocated loops it is better to use C<ev_loop_new>
602	C<ev_loop_new> and C<ev_loop_destroy>.	704	and C<ev_loop_destroy>.
603		705
604	=item ev_loop_destroy (loop)	706	=item ev_loop_fork (loop)
605		707
606	Like C<ev_default_destroy>, but destroys an event loop created by an
607	earlier call to C<ev_loop_new>.
608
609	=item ev_default_fork ()
610
611	This function sets a flag that causes subsequent C<ev_loop> iterations	708	This function sets a flag that causes subsequent C<ev_run> iterations
612	to reinitialise the kernel state for backends that have one. Despite the	709	to reinitialise the kernel state for backends that have one. Despite
613	name, you can call it anytime, but it makes most sense after forking, in	710	the name, you can call it anytime you are allowed to start or stop
614	the child process (or both child and parent, but that again makes little	711	watchers (except inside an C<ev_prepare> callback), but it makes most
615	sense). You I<must> call it in the child before using any of the libev	712	sense after forking, in the child process. You I<must> call it (or use
616	functions, and it will only take effect at the next C<ev_loop> iteration.	713	C<EVFLAG_FORKCHECK>) in the child before resuming or calling C<ev_run>.
617		714
		715	In addition, if you want to reuse a loop (via this function or
		716	C<EVFLAG_FORKCHECK>), you I<also> have to ignore C<SIGPIPE>.
		717
618	Again, you I<have> to call it on I<any> loop that you want to re-use after	718	Again, you I<have> to call it on I<any> loop that you want to re-use after
619	a fork, I<even if you do not plan to use the loop in the parent>. This is	719	a fork, I<even if you do not plan to use the loop in the parent>. This is
620	because some kernel interfaces *cough* I<kqueue> *cough* do funny things	720	because some kernel interfaces *cough* I<kqueue> *cough* do funny things
621	during fork.	721	during fork.
622		722
623	On the other hand, you only need to call this function in the child	723	On the other hand, you only need to call this function in the child
624	process if and only if you want to use the event loop in the child. If you	724	process if and only if you want to use the event loop in the child. If
625	just fork+exec or create a new loop in the child, you don't have to call	725	you just fork+exec or create a new loop in the child, you don't have to
626	it at all.	726	call it at all (in fact, C<epoll> is so badly broken that it makes a
		727	difference, but libev will usually detect this case on its own and do a
		728	costly reset of the backend).
627		729
628	The function itself is quite fast and it's usually not a problem to call	730	The function itself is quite fast and it's usually not a problem to call
629	it just in case after a fork. To make this easy, the function will fit in	731	it just in case after a fork.
630	quite nicely into a call to C<pthread_atfork>:
631		732
		733	Example: Automate calling C<ev_loop_fork> on the default loop when
		734	using pthreads.
		735
		736	static void
		737	post_fork_child (void)
		738	{
		739	ev_loop_fork (EV_DEFAULT);
		740	}
		741
		742	...
632	pthread_atfork (0, 0, ev_default_fork);	743	pthread_atfork (0, 0, post_fork_child);
633
634	=item ev_loop_fork (loop)
635
636	Like C<ev_default_fork>, but acts on an event loop created by
637	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
638	after fork that you want to re-use in the child, and how you keep track of
639	them is entirely your own problem.
640		744
641	=item int ev_is_default_loop (loop)	745	=item int ev_is_default_loop (loop)
642		746
643	Returns true when the given loop is, in fact, the default loop, and false	747	Returns true when the given loop is, in fact, the default loop, and false
644	otherwise.	748	otherwise.
645		749
646	=item unsigned int ev_iteration (loop)	750	=item unsigned int ev_iteration (loop)
647		751
648	Returns the current iteration count for the loop, which is identical to	752	Returns the current iteration count for the event loop, which is identical
649	the number of times libev did poll for new events. It starts at C<0> and	753	to the number of times libev did poll for new events. It starts at C<0>
650	happily wraps around with enough iterations.	754	and happily wraps around with enough iterations.
651		755
652	This value can sometimes be useful as a generation counter of sorts (it	756	This value can sometimes be useful as a generation counter of sorts (it
653	"ticks" the number of loop iterations), as it roughly corresponds with	757	"ticks" the number of loop iterations), as it roughly corresponds with
654	C<ev_prepare> and C<ev_check> calls - and is incremented between the	758	C<ev_prepare> and C<ev_check> calls - and is incremented between the
655	prepare and check phases.	759	prepare and check phases.
656		760
657	=item unsigned int ev_depth (loop)	761	=item unsigned int ev_depth (loop)
658		762
659	Returns the number of times C<ev_loop> was entered minus the number of	763	Returns the number of times C<ev_run> was entered minus the number of
660	times C<ev_loop> was exited, in other words, the recursion depth.	764	times C<ev_run> was exited normally, in other words, the recursion depth.
661		765
662	Outside C<ev_loop>, this number is zero. In a callback, this number is	766	Outside C<ev_run>, this number is zero. In a callback, this number is
663	C<1>, unless C<ev_loop> was invoked recursively (or from another thread),	767	C<1>, unless C<ev_run> was invoked recursively (or from another thread),
664	in which case it is higher.	768	in which case it is higher.
665		769
666	Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread	770	Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread,
667	etc.), doesn't count as "exit" - consider this as a hint to avoid such	771	throwing an exception etc.), doesn't count as "exit" - consider this
668	ungentleman behaviour unless it's really convenient.	772	as a hint to avoid such ungentleman-like behaviour unless it's really
		773	convenient, in which case it is fully supported.
669		774
670	=item unsigned int ev_backend (loop)	775	=item unsigned int ev_backend (loop)
671		776
672	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	777	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
673	use.	778	use.
…		…
682		787
683	=item ev_now_update (loop)	788	=item ev_now_update (loop)
684		789
685	Establishes the current time by querying the kernel, updating the time	790	Establishes the current time by querying the kernel, updating the time
686	returned by C<ev_now ()> in the progress. This is a costly operation and	791	returned by C<ev_now ()> in the progress. This is a costly operation and
687	is usually done automatically within C<ev_loop ()>.	792	is usually done automatically within C<ev_run ()>.
688		793
689	This function is rarely useful, but when some event callback runs for a	794	This function is rarely useful, but when some event callback runs for a
690	very long time without entering the event loop, updating libev's idea of	795	very long time without entering the event loop, updating libev's idea of
691	the current time is a good idea.	796	the current time is a good idea.
692		797
693	See also L<The special problem of time updates> in the C<ev_timer> section.	798	See also L</The special problem of time updates> in the C<ev_timer> section.
694		799
695	=item ev_suspend (loop)	800	=item ev_suspend (loop)
696		801
697	=item ev_resume (loop)	802	=item ev_resume (loop)
698		803
699	These two functions suspend and resume a loop, for use when the loop is	804	These two functions suspend and resume an event loop, for use when the
700	not used for a while and timeouts should not be processed.	805	loop is not used for a while and timeouts should not be processed.
701		806
702	A typical use case would be an interactive program such as a game: When	807	A typical use case would be an interactive program such as a game: When
703	the user presses C<^Z> to suspend the game and resumes it an hour later it	808	the user presses C<^Z> to suspend the game and resumes it an hour later it
704	would be best to handle timeouts as if no time had actually passed while	809	would be best to handle timeouts as if no time had actually passed while
705	the program was suspended. This can be achieved by calling C<ev_suspend>	810	the program was suspended. This can be achieved by calling C<ev_suspend>
…		…
716	without a previous call to C<ev_suspend>.	821	without a previous call to C<ev_suspend>.
717		822
718	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the	823	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the
719	event loop time (see C<ev_now_update>).	824	event loop time (see C<ev_now_update>).
720		825
721	=item ev_loop (loop, int flags)	826	=item bool ev_run (loop, int flags)
722		827
723	Finally, this is it, the event handler. This function usually is called	828	Finally, this is it, the event handler. This function usually is called
724	after you have initialised all your watchers and you want to start	829	after you have initialised all your watchers and you want to start
725	handling events.	830	handling events. It will ask the operating system for any new events, call
		831	the watcher callbacks, and then repeat the whole process indefinitely: This
		832	is why event loops are called I<loops>.
726		833
727	If the flags argument is specified as C<0>, it will not return until	834	If the flags argument is specified as C<0>, it will keep handling events
728	either no event watchers are active anymore or C<ev_unloop> was called.	835	until either no event watchers are active anymore or C<ev_break> was
		836	called.
729		837
		838	The return value is false if there are no more active watchers (which
		839	usually means "all jobs done" or "deadlock"), and true in all other cases
		840	(which usually means " you should call C<ev_run> again").
		841
730	Please note that an explicit C<ev_unloop> is usually better than	842	Please note that an explicit C<ev_break> is usually better than
731	relying on all watchers to be stopped when deciding when a program has	843	relying on all watchers to be stopped when deciding when a program has
732	finished (especially in interactive programs), but having a program	844	finished (especially in interactive programs), but having a program
733	that automatically loops as long as it has to and no longer by virtue	845	that automatically loops as long as it has to and no longer by virtue
734	of relying on its watchers stopping correctly, that is truly a thing of	846	of relying on its watchers stopping correctly, that is truly a thing of
735	beauty.	847	beauty.
736		848
		849	This function is I<mostly> exception-safe - you can break out of a
		850	C<ev_run> call by calling C<longjmp> in a callback, throwing a C++
		851	exception and so on. This does not decrement the C<ev_depth> value, nor
		852	will it clear any outstanding C<EVBREAK_ONE> breaks.
		853
737	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle	854	A flags value of C<EVRUN_NOWAIT> will look for new events, will handle
738	those events and any already outstanding ones, but will not block your	855	those events and any already outstanding ones, but will not wait and
739	process in case there are no events and will return after one iteration of	856	block your process in case there are no events and will return after one
740	the loop.	857	iteration of the loop. This is sometimes useful to poll and handle new
		858	events while doing lengthy calculations, to keep the program responsive.
741		859
742	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if	860	A flags value of C<EVRUN_ONCE> will look for new events (waiting if
743	necessary) and will handle those and any already outstanding ones. It	861	necessary) and will handle those and any already outstanding ones. It
744	will block your process until at least one new event arrives (which could	862	will block your process until at least one new event arrives (which could
745	be an event internal to libev itself, so there is no guarantee that a	863	be an event internal to libev itself, so there is no guarantee that a
746	user-registered callback will be called), and will return after one	864	user-registered callback will be called), and will return after one
747	iteration of the loop.	865	iteration of the loop.
748		866
749	This is useful if you are waiting for some external event in conjunction	867	This is useful if you are waiting for some external event in conjunction
750	with something not expressible using other libev watchers (i.e. "roll your	868	with something not expressible using other libev watchers (i.e. "roll your
751	own C<ev_loop>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is	869	own C<ev_run>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is
752	usually a better approach for this kind of thing.	870	usually a better approach for this kind of thing.
753		871
754	Here are the gory details of what C<ev_loop> does:	872	Here are the gory details of what C<ev_run> does (this is for your
		873	understanding, not a guarantee that things will work exactly like this in
		874	future versions):
755		875
		876	- Increment loop depth.
		877	- Reset the ev_break status.
756	- Before the first iteration, call any pending watchers.	878	- Before the first iteration, call any pending watchers.
		879	LOOP:
757	* If EVFLAG_FORKCHECK was used, check for a fork.	880	- If EVFLAG_FORKCHECK was used, check for a fork.
758	- If a fork was detected (by any means), queue and call all fork watchers.	881	- If a fork was detected (by any means), queue and call all fork watchers.
759	- Queue and call all prepare watchers.	882	- Queue and call all prepare watchers.
		883	- If ev_break was called, goto FINISH.
760	- If we have been forked, detach and recreate the kernel state	884	- If we have been forked, detach and recreate the kernel state
761	as to not disturb the other process.	885	as to not disturb the other process.
762	- Update the kernel state with all outstanding changes.	886	- Update the kernel state with all outstanding changes.
763	- Update the "event loop time" (ev_now ()).	887	- Update the "event loop time" (ev_now ()).
764	- Calculate for how long to sleep or block, if at all	888	- Calculate for how long to sleep or block, if at all
765	(active idle watchers, EVLOOP_NONBLOCK or not having	889	(active idle watchers, EVRUN_NOWAIT or not having
766	any active watchers at all will result in not sleeping).	890	any active watchers at all will result in not sleeping).
767	- Sleep if the I/O and timer collect interval say so.	891	- Sleep if the I/O and timer collect interval say so.
		892	- Increment loop iteration counter.
768	- Block the process, waiting for any events.	893	- Block the process, waiting for any events.
769	- Queue all outstanding I/O (fd) events.	894	- Queue all outstanding I/O (fd) events.
770	- Update the "event loop time" (ev_now ()), and do time jump adjustments.	895	- Update the "event loop time" (ev_now ()), and do time jump adjustments.
771	- Queue all expired timers.	896	- Queue all expired timers.
772	- Queue all expired periodics.	897	- Queue all expired periodics.
773	- Unless any events are pending now, queue all idle watchers.	898	- Queue all idle watchers with priority higher than that of pending events.
774	- Queue all check watchers.	899	- Queue all check watchers.
775	- Call all queued watchers in reverse order (i.e. check watchers first).	900	- Call all queued watchers in reverse order (i.e. check watchers first).
776	Signals and child watchers are implemented as I/O watchers, and will	901	Signals and child watchers are implemented as I/O watchers, and will
777	be handled here by queueing them when their watcher gets executed.	902	be handled here by queueing them when their watcher gets executed.
778	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	903	- If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT
779	were used, or there are no active watchers, return, otherwise	904	were used, or there are no active watchers, goto FINISH, otherwise
780	continue with step *.	905	continue with step LOOP.
		906	FINISH:
		907	- Reset the ev_break status iff it was EVBREAK_ONE.
		908	- Decrement the loop depth.
		909	- Return.
781		910
782	Example: Queue some jobs and then loop until no events are outstanding	911	Example: Queue some jobs and then loop until no events are outstanding
783	anymore.	912	anymore.
784		913
785	... queue jobs here, make sure they register event watchers as long	914	... queue jobs here, make sure they register event watchers as long
786	... as they still have work to do (even an idle watcher will do..)	915	... as they still have work to do (even an idle watcher will do..)
787	ev_loop (my_loop, 0);	916	ev_run (my_loop, 0);
788	... jobs done or somebody called unloop. yeah!	917	... jobs done or somebody called break. yeah!
789		918
790	=item ev_unloop (loop, how)	919	=item ev_break (loop, how)
791		920
792	Can be used to make a call to C<ev_loop> return early (but only after it	921	Can be used to make a call to C<ev_run> return early (but only after it
793	has processed all outstanding events). The C<how> argument must be either	922	has processed all outstanding events). The C<how> argument must be either
794	C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or	923	C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or
795	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.	924	C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return.
796		925
797	This "unloop state" will be cleared when entering C<ev_loop> again.	926	This "break state" will be cleared on the next call to C<ev_run>.
798		927
799	It is safe to call C<ev_unloop> from outside any C<ev_loop> calls.	928	It is safe to call C<ev_break> from outside any C<ev_run> calls, too, in
		929	which case it will have no effect.
800		930
801	=item ev_ref (loop)	931	=item ev_ref (loop)
802		932
803	=item ev_unref (loop)	933	=item ev_unref (loop)
804		934
805	Ref/unref can be used to add or remove a reference count on the event	935	Ref/unref can be used to add or remove a reference count on the event
806	loop: Every watcher keeps one reference, and as long as the reference	936	loop: Every watcher keeps one reference, and as long as the reference
807	count is nonzero, C<ev_loop> will not return on its own.	937	count is nonzero, C<ev_run> will not return on its own.
808		938
809	This is useful when you have a watcher that you never intend to	939	This is useful when you have a watcher that you never intend to
810	unregister, but that nevertheless should not keep C<ev_loop> from	940	unregister, but that nevertheless should not keep C<ev_run> from
811	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>	941	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>
812	before stopping it.	942	before stopping it.
813		943
814	As an example, libev itself uses this for its internal signal pipe: It	944	As an example, libev itself uses this for its internal signal pipe: It
815	is not visible to the libev user and should not keep C<ev_loop> from	945	is not visible to the libev user and should not keep C<ev_run> from
816	exiting if no event watchers registered by it are active. It is also an	946	exiting if no event watchers registered by it are active. It is also an
817	excellent way to do this for generic recurring timers or from within	947	excellent way to do this for generic recurring timers or from within
818	third-party libraries. Just remember to I<unref after start> and I<ref	948	third-party libraries. Just remember to I<unref after start> and I<ref
819	before stop> (but only if the watcher wasn't active before, or was active	949	before stop> (but only if the watcher wasn't active before, or was active
820	before, respectively. Note also that libev might stop watchers itself	950	before, respectively. Note also that libev might stop watchers itself
821	(e.g. non-repeating timers) in which case you have to C<ev_ref>	951	(e.g. non-repeating timers) in which case you have to C<ev_ref>
822	in the callback).	952	in the callback).
823		953
824	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	954	Example: Create a signal watcher, but keep it from keeping C<ev_run>
825	running when nothing else is active.	955	running when nothing else is active.
826		956
827	ev_signal exitsig;	957	ev_signal exitsig;
828	ev_signal_init (&exitsig, sig_cb, SIGINT);	958	ev_signal_init (&exitsig, sig_cb, SIGINT);
829	ev_signal_start (loop, &exitsig);	959	ev_signal_start (loop, &exitsig);
830	evf_unref (loop);	960	ev_unref (loop);
831		961
832	Example: For some weird reason, unregister the above signal handler again.	962	Example: For some weird reason, unregister the above signal handler again.
833		963
834	ev_ref (loop);	964	ev_ref (loop);
835	ev_signal_stop (loop, &exitsig);	965	ev_signal_stop (loop, &exitsig);
…		…
855	overhead for the actual polling but can deliver many events at once.	985	overhead for the actual polling but can deliver many events at once.
856		986
857	By setting a higher I<io collect interval> you allow libev to spend more	987	By setting a higher I<io collect interval> you allow libev to spend more
858	time collecting I/O events, so you can handle more events per iteration,	988	time collecting I/O events, so you can handle more events per iteration,
859	at the cost of increasing latency. Timeouts (both C<ev_periodic> and	989	at the cost of increasing latency. Timeouts (both C<ev_periodic> and
860	C<ev_timer>) will be not affected. Setting this to a non-null value will	990	C<ev_timer>) will not be affected. Setting this to a non-null value will
861	introduce an additional C<ev_sleep ()> call into most loop iterations. The	991	introduce an additional C<ev_sleep ()> call into most loop iterations. The
862	sleep time ensures that libev will not poll for I/O events more often then	992	sleep time ensures that libev will not poll for I/O events more often then
863	once per this interval, on average.	993	once per this interval, on average (as long as the host time resolution is
		994	good enough).
864		995
865	Likewise, by setting a higher I<timeout collect interval> you allow libev	996	Likewise, by setting a higher I<timeout collect interval> you allow libev
866	to spend more time collecting timeouts, at the expense of increased	997	to spend more time collecting timeouts, at the expense of increased
867	latency/jitter/inexactness (the watcher callback will be called	998	latency/jitter/inexactness (the watcher callback will be called
868	later). C<ev_io> watchers will not be affected. Setting this to a non-null	999	later). C<ev_io> watchers will not be affected. Setting this to a non-null
…		…
892	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);	1023	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);
893		1024
894	=item ev_invoke_pending (loop)	1025	=item ev_invoke_pending (loop)
895		1026
896	This call will simply invoke all pending watchers while resetting their	1027	This call will simply invoke all pending watchers while resetting their
897	pending state. Normally, C<ev_loop> does this automatically when required,	1028	pending state. Normally, C<ev_run> does this automatically when required,
898	but when overriding the invoke callback this call comes handy.	1029	but when overriding the invoke callback this call comes handy. This
		1030	function can be invoked from a watcher - this can be useful for example
		1031	when you want to do some lengthy calculation and want to pass further
		1032	event handling to another thread (you still have to make sure only one
		1033	thread executes within C<ev_invoke_pending> or C<ev_run> of course).
899		1034
900	=item int ev_pending_count (loop)	1035	=item int ev_pending_count (loop)
901		1036
902	Returns the number of pending watchers - zero indicates that no watchers	1037	Returns the number of pending watchers - zero indicates that no watchers
903	are pending.	1038	are pending.
904		1039
905	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))	1040	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))
906		1041
907	This overrides the invoke pending functionality of the loop: Instead of	1042	This overrides the invoke pending functionality of the loop: Instead of
908	invoking all pending watchers when there are any, C<ev_loop> will call	1043	invoking all pending watchers when there are any, C<ev_run> will call
909	this callback instead. This is useful, for example, when you want to	1044	this callback instead. This is useful, for example, when you want to
910	invoke the actual watchers inside another context (another thread etc.).	1045	invoke the actual watchers inside another context (another thread etc.).
911		1046
912	If you want to reset the callback, use C<ev_invoke_pending> as new	1047	If you want to reset the callback, use C<ev_invoke_pending> as new
913	callback.	1048	callback.
914		1049
915	=item ev_set_loop_release_cb (loop, void (*release)(EV_P), void (*acquire)(EV_P))	1050	=item ev_set_loop_release_cb (loop, void (*release)(EV_P) throw (), void (*acquire)(EV_P) throw ())
916		1051
917	Sometimes you want to share the same loop between multiple threads. This	1052	Sometimes you want to share the same loop between multiple threads. This
918	can be done relatively simply by putting mutex_lock/unlock calls around	1053	can be done relatively simply by putting mutex_lock/unlock calls around
919	each call to a libev function.	1054	each call to a libev function.
920		1055
921	However, C<ev_loop> can run an indefinite time, so it is not feasible to	1056	However, C<ev_run> can run an indefinite time, so it is not feasible
922	wait for it to return. One way around this is to wake up the loop via	1057	to wait for it to return. One way around this is to wake up the event
923	C<ev_unloop> and C<av_async_send>, another way is to set these I<release>	1058	loop via C<ev_break> and C<ev_async_send>, another way is to set these
924	and I<acquire> callbacks on the loop.	1059	I<release> and I<acquire> callbacks on the loop.
925		1060
926	When set, then C<release> will be called just before the thread is	1061	When set, then C<release> will be called just before the thread is
927	suspended waiting for new events, and C<acquire> is called just	1062	suspended waiting for new events, and C<acquire> is called just
928	afterwards.	1063	afterwards.
929		1064
…		…
932		1067
933	While event loop modifications are allowed between invocations of	1068	While event loop modifications are allowed between invocations of
934	C<release> and C<acquire> (that's their only purpose after all), no	1069	C<release> and C<acquire> (that's their only purpose after all), no
935	modifications done will affect the event loop, i.e. adding watchers will	1070	modifications done will affect the event loop, i.e. adding watchers will
936	have no effect on the set of file descriptors being watched, or the time	1071	have no effect on the set of file descriptors being watched, or the time
937	waited. Use an C<ev_async> watcher to wake up C<ev_loop> when you want it	1072	waited. Use an C<ev_async> watcher to wake up C<ev_run> when you want it
938	to take note of any changes you made.	1073	to take note of any changes you made.
939		1074
940	In theory, threads executing C<ev_loop> will be async-cancel safe between	1075	In theory, threads executing C<ev_run> will be async-cancel safe between
941	invocations of C<release> and C<acquire>.	1076	invocations of C<release> and C<acquire>.
942		1077
943	See also the locking example in the C<THREADS> section later in this	1078	See also the locking example in the C<THREADS> section later in this
944	document.	1079	document.
945		1080
946	=item ev_set_userdata (loop, void *data)	1081	=item ev_set_userdata (loop, void *data)
947		1082
948	=item ev_userdata (loop)	1083	=item void *ev_userdata (loop)
949		1084
950	Set and retrieve a single C<void *> associated with a loop. When	1085	Set and retrieve a single C<void *> associated with a loop. When
951	C<ev_set_userdata> has never been called, then C<ev_userdata> returns	1086	C<ev_set_userdata> has never been called, then C<ev_userdata> returns
952	C<0.>	1087	C<0>.
953		1088
954	These two functions can be used to associate arbitrary data with a loop,	1089	These two functions can be used to associate arbitrary data with a loop,
955	and are intended solely for the C<invoke_pending_cb>, C<release> and	1090	and are intended solely for the C<invoke_pending_cb>, C<release> and
956	C<acquire> callbacks described above, but of course can be (ab-)used for	1091	C<acquire> callbacks described above, but of course can be (ab-)used for
957	any other purpose as well.	1092	any other purpose as well.
958		1093
959	=item ev_loop_verify (loop)	1094	=item ev_verify (loop)
960		1095
961	This function only does something when C<EV_VERIFY> support has been	1096	This function only does something when C<EV_VERIFY> support has been
962	compiled in, which is the default for non-minimal builds. It tries to go	1097	compiled in, which is the default for non-minimal builds. It tries to go
963	through all internal structures and checks them for validity. If anything	1098	through all internal structures and checks them for validity. If anything
964	is found to be inconsistent, it will print an error message to standard	1099	is found to be inconsistent, it will print an error message to standard
…		…
975		1110
976	In the following description, uppercase C<TYPE> in names stands for the	1111	In the following description, uppercase C<TYPE> in names stands for the
977	watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer	1112	watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer
978	watchers and C<ev_io_start> for I/O watchers.	1113	watchers and C<ev_io_start> for I/O watchers.
979		1114
980	A watcher is a structure that you create and register to record your	1115	A watcher is an opaque structure that you allocate and register to record
981	interest in some event. For instance, if you want to wait for STDIN to	1116	your interest in some event. To make a concrete example, imagine you want
982	become readable, you would create an C<ev_io> watcher for that:	1117	to wait for STDIN to become readable, you would create an C<ev_io> watcher
		1118	for that:
983		1119
984	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)	1120	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)
985	{	1121	{
986	ev_io_stop (w);	1122	ev_io_stop (w);
987	ev_unloop (loop, EVUNLOOP_ALL);	1123	ev_break (loop, EVBREAK_ALL);
988	}	1124	}
989		1125
990	struct ev_loop *loop = ev_default_loop (0);	1126	struct ev_loop *loop = ev_default_loop (0);
991		1127
992	ev_io stdin_watcher;	1128	ev_io stdin_watcher;
993		1129
994	ev_init (&stdin_watcher, my_cb);	1130	ev_init (&stdin_watcher, my_cb);
995	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	1131	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
996	ev_io_start (loop, &stdin_watcher);	1132	ev_io_start (loop, &stdin_watcher);
997		1133
998	ev_loop (loop, 0);	1134	ev_run (loop, 0);
999		1135
1000	As you can see, you are responsible for allocating the memory for your	1136	As you can see, you are responsible for allocating the memory for your
1001	watcher structures (and it is I<usually> a bad idea to do this on the	1137	watcher structures (and it is I<usually> a bad idea to do this on the
1002	stack).	1138	stack).
1003		1139
1004	Each watcher has an associated watcher structure (called C<struct ev_TYPE>	1140	Each watcher has an associated watcher structure (called C<struct ev_TYPE>
1005	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).	1141	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).
1006		1142
1007	Each watcher structure must be initialised by a call to C<ev_init	1143	Each watcher structure must be initialised by a call to C<ev_init (watcher
1008	(watcher *, callback)>, which expects a callback to be provided. This	1144	*, callback)>, which expects a callback to be provided. This callback is
1009	callback gets invoked each time the event occurs (or, in the case of I/O	1145	invoked each time the event occurs (or, in the case of I/O watchers, each
1010	watchers, each time the event loop detects that the file descriptor given	1146	time the event loop detects that the file descriptor given is readable
1011	is readable and/or writable).	1147	and/or writable).
1012		1148
1013	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>	1149	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>
1014	macro to configure it, with arguments specific to the watcher type. There	1150	macro to configure it, with arguments specific to the watcher type. There
1015	is also a macro to combine initialisation and setting in one call: C<<	1151	is also a macro to combine initialisation and setting in one call: C<<
1016	ev_TYPE_init (watcher *, callback, ...) >>.	1152	ev_TYPE_init (watcher *, callback, ...) >>.
…		…
1067		1203
1068	=item C<EV_PREPARE>	1204	=item C<EV_PREPARE>
1069		1205
1070	=item C<EV_CHECK>	1206	=item C<EV_CHECK>
1071		1207
1072	All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts	1208	All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts to
1073	to gather new events, and all C<ev_check> watchers are invoked just after	1209	gather new events, and all C<ev_check> watchers are queued (not invoked)
1074	C<ev_loop> has gathered them, but before it invokes any callbacks for any	1210	just after C<ev_run> has gathered them, but before it queues any callbacks
		1211	for any received events. That means C<ev_prepare> watchers are the last
		1212	watchers invoked before the event loop sleeps or polls for new events, and
		1213	C<ev_check> watchers will be invoked before any other watchers of the same
		1214	or lower priority within an event loop iteration.
		1215
1075	received events. Callbacks of both watcher types can start and stop as	1216	Callbacks of both watcher types can start and stop as many watchers as
1076	many watchers as they want, and all of them will be taken into account	1217	they want, and all of them will be taken into account (for example, a
1077	(for example, a C<ev_prepare> watcher might start an idle watcher to keep	1218	C<ev_prepare> watcher might start an idle watcher to keep C<ev_run> from
1078	C<ev_loop> from blocking).	1219	blocking).
1079		1220
1080	=item C<EV_EMBED>	1221	=item C<EV_EMBED>
1081		1222
1082	The embedded event loop specified in the C<ev_embed> watcher needs attention.	1223	The embedded event loop specified in the C<ev_embed> watcher needs attention.
1083		1224
1084	=item C<EV_FORK>	1225	=item C<EV_FORK>
1085		1226
1086	The event loop has been resumed in the child process after fork (see	1227	The event loop has been resumed in the child process after fork (see
1087	C<ev_fork>).	1228	C<ev_fork>).
		1229
		1230	=item C<EV_CLEANUP>
		1231
		1232	The event loop is about to be destroyed (see C<ev_cleanup>).
1088		1233
1089	=item C<EV_ASYNC>	1234	=item C<EV_ASYNC>
1090		1235
1091	The given async watcher has been asynchronously notified (see C<ev_async>).	1236	The given async watcher has been asynchronously notified (see C<ev_async>).
1092		1237
…		…
1202		1347
1203	=item callback ev_cb (ev_TYPE *watcher)	1348	=item callback ev_cb (ev_TYPE *watcher)
1204		1349
1205	Returns the callback currently set on the watcher.	1350	Returns the callback currently set on the watcher.
1206		1351
1207	=item ev_cb_set (ev_TYPE *watcher, callback)	1352	=item ev_set_cb (ev_TYPE *watcher, callback)
1208		1353
1209	Change the callback. You can change the callback at virtually any time	1354	Change the callback. You can change the callback at virtually any time
1210	(modulo threads).	1355	(modulo threads).
1211		1356
1212	=item ev_set_priority (ev_TYPE *watcher, int priority)	1357	=item ev_set_priority (ev_TYPE *watcher, int priority)
…		…
1230	or might not have been clamped to the valid range.	1375	or might not have been clamped to the valid range.
1231		1376
1232	The default priority used by watchers when no priority has been set is	1377	The default priority used by watchers when no priority has been set is
1233	always C<0>, which is supposed to not be too high and not be too low :).	1378	always C<0>, which is supposed to not be too high and not be too low :).
1234		1379
1235	See L<WATCHER PRIORITY MODELS>, below, for a more thorough treatment of	1380	See L</WATCHER PRIORITY MODELS>, below, for a more thorough treatment of
1236	priorities.	1381	priorities.
1237		1382
1238	=item ev_invoke (loop, ev_TYPE *watcher, int revents)	1383	=item ev_invoke (loop, ev_TYPE *watcher, int revents)
1239		1384
1240	Invoke the C<watcher> with the given C<loop> and C<revents>. Neither	1385	Invoke the C<watcher> with the given C<loop> and C<revents>. Neither
…		…
1265	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related	1410	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related
1266	functions that do not need a watcher.	1411	functions that do not need a watcher.
1267		1412
1268	=back	1413	=back
1269		1414
		1415	See also the L</ASSOCIATING CUSTOM DATA WITH A WATCHER> and L</BUILDING YOUR
		1416	OWN COMPOSITE WATCHERS> idioms.
1270		1417
1271	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	1418	=head2 WATCHER STATES
1272		1419
1273	Each watcher has, by default, a member C<void *data> that you can change	1420	There are various watcher states mentioned throughout this manual -
1274	and read at any time: libev will completely ignore it. This can be used	1421	active, pending and so on. In this section these states and the rules to
1275	to associate arbitrary data with your watcher. If you need more data and	1422	transition between them will be described in more detail - and while these
1276	don't want to allocate memory and store a pointer to it in that data	1423	rules might look complicated, they usually do "the right thing".
1277	member, you can also "subclass" the watcher type and provide your own
1278	data:
1279		1424
1280	struct my_io	1425	=over 4
1281	{
1282	ev_io io;
1283	int otherfd;
1284	void *somedata;
1285	struct whatever *mostinteresting;
1286	};
1287		1426
1288	...	1427	=item initialised
1289	struct my_io w;
1290	ev_io_init (&w.io, my_cb, fd, EV_READ);
1291		1428
1292	And since your callback will be called with a pointer to the watcher, you	1429	Before a watcher can be registered with the event loop it has to be
1293	can cast it back to your own type:	1430	initialised. This can be done with a call to C<ev_TYPE_init>, or calls to
		1431	C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function.
1294		1432
1295	static void my_cb (struct ev_loop *loop, ev_io *w_, int revents)	1433	In this state it is simply some block of memory that is suitable for
1296	{	1434	use in an event loop. It can be moved around, freed, reused etc. at
1297	struct my_io *w = (struct my_io *)w_;	1435	will - as long as you either keep the memory contents intact, or call
1298	...	1436	C<ev_TYPE_init> again.
1299	}
1300		1437
1301	More interesting and less C-conformant ways of casting your callback type	1438	=item started/running/active
1302	instead have been omitted.
1303		1439
1304	Another common scenario is to use some data structure with multiple	1440	Once a watcher has been started with a call to C<ev_TYPE_start> it becomes
1305	embedded watchers:	1441	property of the event loop, and is actively waiting for events. While in
		1442	this state it cannot be accessed (except in a few documented ways), moved,
		1443	freed or anything else - the only legal thing is to keep a pointer to it,
		1444	and call libev functions on it that are documented to work on active watchers.
1306		1445
1307	struct my_biggy	1446	=item pending
1308	{
1309	int some_data;
1310	ev_timer t1;
1311	ev_timer t2;
1312	}
1313		1447
1314	In this case getting the pointer to C<my_biggy> is a bit more	1448	If a watcher is active and libev determines that an event it is interested
1315	complicated: Either you store the address of your C<my_biggy> struct	1449	in has occurred (such as a timer expiring), it will become pending. It will
1316	in the C<data> member of the watcher (for woozies), or you need to use	1450	stay in this pending state until either it is stopped or its callback is
1317	some pointer arithmetic using C<offsetof> inside your watchers (for real	1451	about to be invoked, so it is not normally pending inside the watcher
1318	programmers):	1452	callback.
1319		1453
1320	#include <stddef.h>	1454	The watcher might or might not be active while it is pending (for example,
		1455	an expired non-repeating timer can be pending but no longer active). If it
		1456	is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>),
		1457	but it is still property of the event loop at this time, so cannot be
		1458	moved, freed or reused. And if it is active the rules described in the
		1459	previous item still apply.
1321		1460
1322	static void	1461	It is also possible to feed an event on a watcher that is not active (e.g.
1323	t1_cb (EV_P_ ev_timer *w, int revents)	1462	via C<ev_feed_event>), in which case it becomes pending without being
1324	{	1463	active.
1325	struct my_biggy big = (struct my_biggy *)
1326	(((char *)w) - offsetof (struct my_biggy, t1));
1327	}
1328		1464
1329	static void	1465	=item stopped
1330	t2_cb (EV_P_ ev_timer *w, int revents)	1466
1331	{	1467	A watcher can be stopped implicitly by libev (in which case it might still
1332	struct my_biggy big = (struct my_biggy *)	1468	be pending), or explicitly by calling its C<ev_TYPE_stop> function. The
1333	(((char *)w) - offsetof (struct my_biggy, t2));	1469	latter will clear any pending state the watcher might be in, regardless
1334	}	1470	of whether it was active or not, so stopping a watcher explicitly before
		1471	freeing it is often a good idea.
		1472
		1473	While stopped (and not pending) the watcher is essentially in the
		1474	initialised state, that is, it can be reused, moved, modified in any way
		1475	you wish (but when you trash the memory block, you need to C<ev_TYPE_init>
		1476	it again).
		1477
		1478	=back
1335		1479
1336	=head2 WATCHER PRIORITY MODELS	1480	=head2 WATCHER PRIORITY MODELS
1337		1481
1338	Many event loops support I<watcher priorities>, which are usually small	1482	Many event loops support I<watcher priorities>, which are usually small
1339	integers that influence the ordering of event callback invocation	1483	integers that influence the ordering of event callback invocation
…		…
1466	In general you can register as many read and/or write event watchers per	1610	In general you can register as many read and/or write event watchers per
1467	fd as you want (as long as you don't confuse yourself). Setting all file	1611	fd as you want (as long as you don't confuse yourself). Setting all file
1468	descriptors to non-blocking mode is also usually a good idea (but not	1612	descriptors to non-blocking mode is also usually a good idea (but not
1469	required if you know what you are doing).	1613	required if you know what you are doing).
1470		1614
1471	If you cannot use non-blocking mode, then force the use of a
1472	known-to-be-good backend (at the time of this writing, this includes only
1473	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file
1474	descriptors for which non-blocking operation makes no sense (such as
1475	files) - libev doesn't guarantee any specific behaviour in that case.
1476
1477	Another thing you have to watch out for is that it is quite easy to	1615	Another thing you have to watch out for is that it is quite easy to
1478	receive "spurious" readiness notifications, that is your callback might	1616	receive "spurious" readiness notifications, that is, your callback might
1479	be called with C<EV_READ> but a subsequent C<read>(2) will actually block	1617	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
1480	because there is no data. Not only are some backends known to create a	1618	because there is no data. It is very easy to get into this situation even
1481	lot of those (for example Solaris ports), it is very easy to get into	1619	with a relatively standard program structure. Thus it is best to always
1482	this situation even with a relatively standard program structure. Thus	1620	use non-blocking I/O: An extra C<read>(2) returning C<EAGAIN> is far
1483	it is best to always use non-blocking I/O: An extra C<read>(2) returning
1484	C<EAGAIN> is far preferable to a program hanging until some data arrives.	1621	preferable to a program hanging until some data arrives.
1485		1622
1486	If you cannot run the fd in non-blocking mode (for example you should	1623	If you cannot run the fd in non-blocking mode (for example you should
1487	not play around with an Xlib connection), then you have to separately	1624	not play around with an Xlib connection), then you have to separately
1488	re-test whether a file descriptor is really ready with a known-to-be good	1625	re-test whether a file descriptor is really ready with a known-to-be good
1489	interface such as poll (fortunately in our Xlib example, Xlib already	1626	interface such as poll (fortunately in the case of Xlib, it already does
1490	does this on its own, so its quite safe to use). Some people additionally	1627	this on its own, so its quite safe to use). Some people additionally
1491	use C<SIGALRM> and an interval timer, just to be sure you won't block	1628	use C<SIGALRM> and an interval timer, just to be sure you won't block
1492	indefinitely.	1629	indefinitely.
1493		1630
1494	But really, best use non-blocking mode.	1631	But really, best use non-blocking mode.
1495		1632
…		…
1523		1660
1524	There is no workaround possible except not registering events	1661	There is no workaround possible except not registering events
1525	for potentially C<dup ()>'ed file descriptors, or to resort to	1662	for potentially C<dup ()>'ed file descriptors, or to resort to
1526	C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>.	1663	C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>.
1527		1664
		1665	=head3 The special problem of files
		1666
		1667	Many people try to use C<select> (or libev) on file descriptors
		1668	representing files, and expect it to become ready when their program
		1669	doesn't block on disk accesses (which can take a long time on their own).
		1670
		1671	However, this cannot ever work in the "expected" way - you get a readiness
		1672	notification as soon as the kernel knows whether and how much data is
		1673	there, and in the case of open files, that's always the case, so you
		1674	always get a readiness notification instantly, and your read (or possibly
		1675	write) will still block on the disk I/O.
		1676
		1677	Another way to view it is that in the case of sockets, pipes, character
		1678	devices and so on, there is another party (the sender) that delivers data
		1679	on its own, but in the case of files, there is no such thing: the disk
		1680	will not send data on its own, simply because it doesn't know what you
		1681	wish to read - you would first have to request some data.
		1682
		1683	Since files are typically not-so-well supported by advanced notification
		1684	mechanism, libev tries hard to emulate POSIX behaviour with respect
		1685	to files, even though you should not use it. The reason for this is
		1686	convenience: sometimes you want to watch STDIN or STDOUT, which is
		1687	usually a tty, often a pipe, but also sometimes files or special devices
		1688	(for example, C<epoll> on Linux works with F</dev/random> but not with
		1689	F</dev/urandom>), and even though the file might better be served with
		1690	asynchronous I/O instead of with non-blocking I/O, it is still useful when
		1691	it "just works" instead of freezing.
		1692
		1693	So avoid file descriptors pointing to files when you know it (e.g. use
		1694	libeio), but use them when it is convenient, e.g. for STDIN/STDOUT, or
		1695	when you rarely read from a file instead of from a socket, and want to
		1696	reuse the same code path.
		1697
1528	=head3 The special problem of fork	1698	=head3 The special problem of fork
1529		1699
1530	Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit	1700	Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit
1531	useless behaviour. Libev fully supports fork, but needs to be told about	1701	useless behaviour. Libev fully supports fork, but needs to be told about
1532	it in the child.	1702	it in the child if you want to continue to use it in the child.
1533		1703
1534	To support fork in your programs, you either have to call	1704	To support fork in your child processes, you have to call C<ev_loop_fork
1535	C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child,	1705	()> after a fork in the child, enable C<EVFLAG_FORKCHECK>, or resort to
1536	enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or	1706	C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>.
1537	C<EVBACKEND_POLL>.
1538		1707
1539	=head3 The special problem of SIGPIPE	1708	=head3 The special problem of SIGPIPE
1540		1709
1541	While not really specific to libev, it is easy to forget about C<SIGPIPE>:	1710	While not really specific to libev, it is easy to forget about C<SIGPIPE>:
1542	when writing to a pipe whose other end has been closed, your program gets	1711	when writing to a pipe whose other end has been closed, your program gets
…		…
1624	...	1793	...
1625	struct ev_loop *loop = ev_default_init (0);	1794	struct ev_loop *loop = ev_default_init (0);
1626	ev_io stdin_readable;	1795	ev_io stdin_readable;
1627	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1796	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1628	ev_io_start (loop, &stdin_readable);	1797	ev_io_start (loop, &stdin_readable);
1629	ev_loop (loop, 0);	1798	ev_run (loop, 0);
1630		1799
1631		1800
1632	=head2 C<ev_timer> - relative and optionally repeating timeouts	1801	=head2 C<ev_timer> - relative and optionally repeating timeouts
1633		1802
1634	Timer watchers are simple relative timers that generate an event after a	1803	Timer watchers are simple relative timers that generate an event after a
…		…
1640	detecting time jumps is hard, and some inaccuracies are unavoidable (the	1809	detecting time jumps is hard, and some inaccuracies are unavoidable (the
1641	monotonic clock option helps a lot here).	1810	monotonic clock option helps a lot here).
1642		1811
1643	The callback is guaranteed to be invoked only I<after> its timeout has	1812	The callback is guaranteed to be invoked only I<after> its timeout has
1644	passed (not I<at>, so on systems with very low-resolution clocks this	1813	passed (not I<at>, so on systems with very low-resolution clocks this
1645	might introduce a small delay). If multiple timers become ready during the	1814	might introduce a small delay, see "the special problem of being too
		1815	early", below). If multiple timers become ready during the same loop
1646	same loop iteration then the ones with earlier time-out values are invoked	1816	iteration then the ones with earlier time-out values are invoked before
1647	before ones of the same priority with later time-out values (but this is	1817	ones of the same priority with later time-out values (but this is no
1648	no longer true when a callback calls C<ev_loop> recursively).	1818	longer true when a callback calls C<ev_run> recursively).
1649		1819
1650	=head3 Be smart about timeouts	1820	=head3 Be smart about timeouts
1651		1821
1652	Many real-world problems involve some kind of timeout, usually for error	1822	Many real-world problems involve some kind of timeout, usually for error
1653	recovery. A typical example is an HTTP request - if the other side hangs,	1823	recovery. A typical example is an HTTP request - if the other side hangs,
…		…
1728		1898
1729	In this case, it would be more efficient to leave the C<ev_timer> alone,	1899	In this case, it would be more efficient to leave the C<ev_timer> alone,
1730	but remember the time of last activity, and check for a real timeout only	1900	but remember the time of last activity, and check for a real timeout only
1731	within the callback:	1901	within the callback:
1732		1902
		1903	ev_tstamp timeout = 60.;
1733	ev_tstamp last_activity; // time of last activity	1904	ev_tstamp last_activity; // time of last activity
		1905	ev_timer timer;
1734		1906
1735	static void	1907	static void
1736	callback (EV_P_ ev_timer *w, int revents)	1908	callback (EV_P_ ev_timer *w, int revents)
1737	{	1909	{
1738	ev_tstamp now = ev_now (EV_A);	1910	// calculate when the timeout would happen
1739	ev_tstamp timeout = last_activity + 60.;	1911	ev_tstamp after = last_activity - ev_now (EV_A) + timeout;
1740		1912
1741	// if last_activity + 60. is older than now, we did time out	1913	// if negative, it means we the timeout already occurred
1742	if (timeout < now)	1914	if (after < 0.)
1743	{	1915	{
1744	// timeout occurred, take action	1916	// timeout occurred, take action
1745	}	1917	}
1746	else	1918	else
1747	{	1919	{
1748	// callback was invoked, but there was some activity, re-arm	1920	// callback was invoked, but there was some recent
1749	// the watcher to fire in last_activity + 60, which is	1921	// activity. simply restart the timer to time out
1750	// guaranteed to be in the future, so "again" is positive:	1922	// after "after" seconds, which is the earliest time
1751	w->repeat = timeout - now;	1923	// the timeout can occur.
		1924	ev_timer_set (w, after, 0.);
1752	ev_timer_again (EV_A_ w);	1925	ev_timer_start (EV_A_ w);
1753	}	1926	}
1754	}	1927	}
1755		1928
1756	To summarise the callback: first calculate the real timeout (defined	1929	To summarise the callback: first calculate in how many seconds the
1757	as "60 seconds after the last activity"), then check if that time has	1930	timeout will occur (by calculating the absolute time when it would occur,
1758	been reached, which means something I<did>, in fact, time out. Otherwise	1931	C<last_activity + timeout>, and subtracting the current time, C<ev_now
1759	the callback was invoked too early (C<timeout> is in the future), so	1932	(EV_A)> from that).
1760	re-schedule the timer to fire at that future time, to see if maybe we have
1761	a timeout then.
1762		1933
1763	Note how C<ev_timer_again> is used, taking advantage of the	1934	If this value is negative, then we are already past the timeout, i.e. we
1764	C<ev_timer_again> optimisation when the timer is already running.	1935	timed out, and need to do whatever is needed in this case.
		1936
		1937	Otherwise, we now the earliest time at which the timeout would trigger,
		1938	and simply start the timer with this timeout value.
		1939
		1940	In other words, each time the callback is invoked it will check whether
		1941	the timeout occurred. If not, it will simply reschedule itself to check
		1942	again at the earliest time it could time out. Rinse. Repeat.
1765		1943
1766	This scheme causes more callback invocations (about one every 60 seconds	1944	This scheme causes more callback invocations (about one every 60 seconds
1767	minus half the average time between activity), but virtually no calls to	1945	minus half the average time between activity), but virtually no calls to
1768	libev to change the timeout.	1946	libev to change the timeout.
1769		1947
1770	To start the timer, simply initialise the watcher and set C<last_activity>	1948	To start the machinery, simply initialise the watcher and set
1771	to the current time (meaning we just have some activity :), then call the	1949	C<last_activity> to the current time (meaning there was some activity just
1772	callback, which will "do the right thing" and start the timer:	1950	now), then call the callback, which will "do the right thing" and start
		1951	the timer:
1773		1952
		1953	last_activity = ev_now (EV_A);
1774	ev_init (timer, callback);	1954	ev_init (&timer, callback);
1775	last_activity = ev_now (loop);	1955	callback (EV_A_ &timer, 0);
1776	callback (loop, timer, EV_TIMER);
1777		1956
1778	And when there is some activity, simply store the current time in	1957	When there is some activity, simply store the current time in
1779	C<last_activity>, no libev calls at all:	1958	C<last_activity>, no libev calls at all:
1780		1959
		1960	if (activity detected)
1781	last_activity = ev_now (loop);	1961	last_activity = ev_now (EV_A);
		1962
		1963	When your timeout value changes, then the timeout can be changed by simply
		1964	providing a new value, stopping the timer and calling the callback, which
		1965	will again do the right thing (for example, time out immediately :).
		1966
		1967	timeout = new_value;
		1968	ev_timer_stop (EV_A_ &timer);
		1969	callback (EV_A_ &timer, 0);
1782		1970
1783	This technique is slightly more complex, but in most cases where the	1971	This technique is slightly more complex, but in most cases where the
1784	time-out is unlikely to be triggered, much more efficient.	1972	time-out is unlikely to be triggered, much more efficient.
1785
1786	Changing the timeout is trivial as well (if it isn't hard-coded in the
1787	callback :) - just change the timeout and invoke the callback, which will
1788	fix things for you.
1789		1973
1790	=item 4. Wee, just use a double-linked list for your timeouts.	1974	=item 4. Wee, just use a double-linked list for your timeouts.
1791		1975
1792	If there is not one request, but many thousands (millions...), all	1976	If there is not one request, but many thousands (millions...), all
1793	employing some kind of timeout with the same timeout value, then one can	1977	employing some kind of timeout with the same timeout value, then one can
…		…
1820	Method #1 is almost always a bad idea, and buys you nothing. Method #4 is	2004	Method #1 is almost always a bad idea, and buys you nothing. Method #4 is
1821	rather complicated, but extremely efficient, something that really pays	2005	rather complicated, but extremely efficient, something that really pays
1822	off after the first million or so of active timers, i.e. it's usually	2006	off after the first million or so of active timers, i.e. it's usually
1823	overkill :)	2007	overkill :)
1824		2008
		2009	=head3 The special problem of being too early
		2010
		2011	If you ask a timer to call your callback after three seconds, then
		2012	you expect it to be invoked after three seconds - but of course, this
		2013	cannot be guaranteed to infinite precision. Less obviously, it cannot be
		2014	guaranteed to any precision by libev - imagine somebody suspending the
		2015	process with a STOP signal for a few hours for example.
		2016
		2017	So, libev tries to invoke your callback as soon as possible I<after> the
		2018	delay has occurred, but cannot guarantee this.
		2019
		2020	A less obvious failure mode is calling your callback too early: many event
		2021	loops compare timestamps with a "elapsed delay >= requested delay", but
		2022	this can cause your callback to be invoked much earlier than you would
		2023	expect.
		2024
		2025	To see why, imagine a system with a clock that only offers full second
		2026	resolution (think windows if you can't come up with a broken enough OS
		2027	yourself). If you schedule a one-second timer at the time 500.9, then the
		2028	event loop will schedule your timeout to elapse at a system time of 500
		2029	(500.9 truncated to the resolution) + 1, or 501.
		2030
		2031	If an event library looks at the timeout 0.1s later, it will see "501 >=
		2032	501" and invoke the callback 0.1s after it was started, even though a
		2033	one-second delay was requested - this is being "too early", despite best
		2034	intentions.
		2035
		2036	This is the reason why libev will never invoke the callback if the elapsed
		2037	delay equals the requested delay, but only when the elapsed delay is
		2038	larger than the requested delay. In the example above, libev would only invoke
		2039	the callback at system time 502, or 1.1s after the timer was started.
		2040
		2041	So, while libev cannot guarantee that your callback will be invoked
		2042	exactly when requested, it I<can> and I<does> guarantee that the requested
		2043	delay has actually elapsed, or in other words, it always errs on the "too
		2044	late" side of things.
		2045
1825	=head3 The special problem of time updates	2046	=head3 The special problem of time updates
1826		2047
1827	Establishing the current time is a costly operation (it usually takes at	2048	Establishing the current time is a costly operation (it usually takes
1828	least two system calls): EV therefore updates its idea of the current	2049	at least one system call): EV therefore updates its idea of the current
1829	time only before and after C<ev_loop> collects new events, which causes a	2050	time only before and after C<ev_run> collects new events, which causes a
1830	growing difference between C<ev_now ()> and C<ev_time ()> when handling	2051	growing difference between C<ev_now ()> and C<ev_time ()> when handling
1831	lots of events in one iteration.	2052	lots of events in one iteration.
1832		2053
1833	The relative timeouts are calculated relative to the C<ev_now ()>	2054	The relative timeouts are calculated relative to the C<ev_now ()>
1834	time. This is usually the right thing as this timestamp refers to the time	2055	time. This is usually the right thing as this timestamp refers to the time
1835	of the event triggering whatever timeout you are modifying/starting. If	2056	of the event triggering whatever timeout you are modifying/starting. If
1836	you suspect event processing to be delayed and you I<need> to base the	2057	you suspect event processing to be delayed and you I<need> to base the
1837	timeout on the current time, use something like this to adjust for this:	2058	timeout on the current time, use something like the following to adjust
		2059	for it:
1838		2060
1839	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);	2061	ev_timer_set (&timer, after + (ev_time () - ev_now ()), 0.);
1840		2062
1841	If the event loop is suspended for a long time, you can also force an	2063	If the event loop is suspended for a long time, you can also force an
1842	update of the time returned by C<ev_now ()> by calling C<ev_now_update	2064	update of the time returned by C<ev_now ()> by calling C<ev_now_update
1843	()>.	2065	()>, although that will push the event time of all outstanding events
		2066	further into the future.
		2067
		2068	=head3 The special problem of unsynchronised clocks
		2069
		2070	Modern systems have a variety of clocks - libev itself uses the normal
		2071	"wall clock" clock and, if available, the monotonic clock (to avoid time
		2072	jumps).
		2073
		2074	Neither of these clocks is synchronised with each other or any other clock
		2075	on the system, so C<ev_time ()> might return a considerably different time
		2076	than C<gettimeofday ()> or C<time ()>. On a GNU/Linux system, for example,
		2077	a call to C<gettimeofday> might return a second count that is one higher
		2078	than a directly following call to C<time>.
		2079
		2080	The moral of this is to only compare libev-related timestamps with
		2081	C<ev_time ()> and C<ev_now ()>, at least if you want better precision than
		2082	a second or so.
		2083
		2084	One more problem arises due to this lack of synchronisation: if libev uses
		2085	the system monotonic clock and you compare timestamps from C<ev_time>
		2086	or C<ev_now> from when you started your timer and when your callback is
		2087	invoked, you will find that sometimes the callback is a bit "early".
		2088
		2089	This is because C<ev_timer>s work in real time, not wall clock time, so
		2090	libev makes sure your callback is not invoked before the delay happened,
		2091	I<measured according to the real time>, not the system clock.
		2092
		2093	If your timeouts are based on a physical timescale (e.g. "time out this
		2094	connection after 100 seconds") then this shouldn't bother you as it is
		2095	exactly the right behaviour.
		2096
		2097	If you want to compare wall clock/system timestamps to your timers, then
		2098	you need to use C<ev_periodic>s, as these are based on the wall clock
		2099	time, where your comparisons will always generate correct results.
1844		2100
1845	=head3 The special problems of suspended animation	2101	=head3 The special problems of suspended animation
1846		2102
1847	When you leave the server world it is quite customary to hit machines that	2103	When you leave the server world it is quite customary to hit machines that
1848	can suspend/hibernate - what happens to the clocks during such a suspend?	2104	can suspend/hibernate - what happens to the clocks during such a suspend?
…		…
1878		2134
1879	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	2135	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
1880		2136
1881	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)	2137	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)
1882		2138
1883	Configure the timer to trigger after C<after> seconds. If C<repeat>	2139	Configure the timer to trigger after C<after> seconds (fractional and
1884	is C<0.>, then it will automatically be stopped once the timeout is	2140	negative values are supported). If C<repeat> is C<0.>, then it will
1885	reached. If it is positive, then the timer will automatically be	2141	automatically be stopped once the timeout is reached. If it is positive,
1886	configured to trigger again C<repeat> seconds later, again, and again,	2142	then the timer will automatically be configured to trigger again C<repeat>
1887	until stopped manually.	2143	seconds later, again, and again, until stopped manually.
1888		2144
1889	The timer itself will do a best-effort at avoiding drift, that is, if	2145	The timer itself will do a best-effort at avoiding drift, that is, if
1890	you configure a timer to trigger every 10 seconds, then it will normally	2146	you configure a timer to trigger every 10 seconds, then it will normally
1891	trigger at exactly 10 second intervals. If, however, your program cannot	2147	trigger at exactly 10 second intervals. If, however, your program cannot
1892	keep up with the timer (because it takes longer than those 10 seconds to	2148	keep up with the timer (because it takes longer than those 10 seconds to
1893	do stuff) the timer will not fire more than once per event loop iteration.	2149	do stuff) the timer will not fire more than once per event loop iteration.
1894		2150
1895	=item ev_timer_again (loop, ev_timer *)	2151	=item ev_timer_again (loop, ev_timer *)
1896		2152
1897	This will act as if the timer timed out and restart it again if it is	2153	This will act as if the timer timed out, and restarts it again if it is
1898	repeating. The exact semantics are:	2154	repeating. It basically works like calling C<ev_timer_stop>, updating the
		2155	timeout to the C<repeat> value and calling C<ev_timer_start>.
1899		2156
		2157	The exact semantics are as in the following rules, all of which will be
		2158	applied to the watcher:
		2159
		2160	=over 4
		2161
1900	If the timer is pending, its pending status is cleared.	2162	=item If the timer is pending, the pending status is always cleared.
1901		2163
1902	If the timer is started but non-repeating, stop it (as if it timed out).	2164	=item If the timer is started but non-repeating, stop it (as if it timed
		2165	out, without invoking it).
1903		2166
1904	If the timer is repeating, either start it if necessary (with the	2167	=item If the timer is repeating, make the C<repeat> value the new timeout
1905	C<repeat> value), or reset the running timer to the C<repeat> value.	2168	and start the timer, if necessary.
1906		2169
		2170	=back
		2171
1907	This sounds a bit complicated, see L<Be smart about timeouts>, above, for a	2172	This sounds a bit complicated, see L</Be smart about timeouts>, above, for a
1908	usage example.	2173	usage example.
1909		2174
1910	=item ev_tstamp ev_timer_remaining (loop, ev_timer *)	2175	=item ev_tstamp ev_timer_remaining (loop, ev_timer *)
1911		2176
1912	Returns the remaining time until a timer fires. If the timer is active,	2177	Returns the remaining time until a timer fires. If the timer is active,
…		…
1951	}	2216	}
1952		2217
1953	ev_timer mytimer;	2218	ev_timer mytimer;
1954	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	2219	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1955	ev_timer_again (&mytimer); /* start timer */	2220	ev_timer_again (&mytimer); /* start timer */
1956	ev_loop (loop, 0);	2221	ev_run (loop, 0);
1957		2222
1958	// and in some piece of code that gets executed on any "activity":	2223	// and in some piece of code that gets executed on any "activity":
1959	// reset the timeout to start ticking again at 10 seconds	2224	// reset the timeout to start ticking again at 10 seconds
1960	ev_timer_again (&mytimer);	2225	ev_timer_again (&mytimer);
1961		2226
…		…
1965	Periodic watchers are also timers of a kind, but they are very versatile	2230	Periodic watchers are also timers of a kind, but they are very versatile
1966	(and unfortunately a bit complex).	2231	(and unfortunately a bit complex).
1967		2232
1968	Unlike C<ev_timer>, periodic watchers are not based on real time (or	2233	Unlike C<ev_timer>, periodic watchers are not based on real time (or
1969	relative time, the physical time that passes) but on wall clock time	2234	relative time, the physical time that passes) but on wall clock time
1970	(absolute time, the thing you can read on your calender or clock). The	2235	(absolute time, the thing you can read on your calendar or clock). The
1971	difference is that wall clock time can run faster or slower than real	2236	difference is that wall clock time can run faster or slower than real
1972	time, and time jumps are not uncommon (e.g. when you adjust your	2237	time, and time jumps are not uncommon (e.g. when you adjust your
1973	wrist-watch).	2238	wrist-watch).
1974		2239
1975	You can tell a periodic watcher to trigger after some specific point	2240	You can tell a periodic watcher to trigger after some specific point
…		…
1980	C<ev_timer>, which would still trigger roughly 10 seconds after starting	2245	C<ev_timer>, which would still trigger roughly 10 seconds after starting
1981	it, as it uses a relative timeout).	2246	it, as it uses a relative timeout).
1982		2247
1983	C<ev_periodic> watchers can also be used to implement vastly more complex	2248	C<ev_periodic> watchers can also be used to implement vastly more complex
1984	timers, such as triggering an event on each "midnight, local time", or	2249	timers, such as triggering an event on each "midnight, local time", or
1985	other complicated rules. This cannot be done with C<ev_timer> watchers, as	2250	other complicated rules. This cannot easily be done with C<ev_timer>
1986	those cannot react to time jumps.	2251	watchers, as those cannot react to time jumps.
1987		2252
1988	As with timers, the callback is guaranteed to be invoked only when the	2253	As with timers, the callback is guaranteed to be invoked only when the
1989	point in time where it is supposed to trigger has passed. If multiple	2254	point in time where it is supposed to trigger has passed. If multiple
1990	timers become ready during the same loop iteration then the ones with	2255	timers become ready during the same loop iteration then the ones with
1991	earlier time-out values are invoked before ones with later time-out values	2256	earlier time-out values are invoked before ones with later time-out values
1992	(but this is no longer true when a callback calls C<ev_loop> recursively).	2257	(but this is no longer true when a callback calls C<ev_run> recursively).
1993		2258
1994	=head3 Watcher-Specific Functions and Data Members	2259	=head3 Watcher-Specific Functions and Data Members
1995		2260
1996	=over 4	2261	=over 4
1997		2262
…		…
2032		2297
2033	Another way to think about it (for the mathematically inclined) is that	2298	Another way to think about it (for the mathematically inclined) is that
2034	C<ev_periodic> will try to run the callback in this mode at the next possible	2299	C<ev_periodic> will try to run the callback in this mode at the next possible
2035	time where C<time = offset (mod interval)>, regardless of any time jumps.	2300	time where C<time = offset (mod interval)>, regardless of any time jumps.
2036		2301
2037	For numerical stability it is preferable that the C<offset> value is near	2302	The C<interval> I<MUST> be positive, and for numerical stability, the
2038	C<ev_now ()> (the current time), but there is no range requirement for	2303	interval value should be higher than C<1/8192> (which is around 100
2039	this value, and in fact is often specified as zero.	2304	microseconds) and C<offset> should be higher than C<0> and should have
		2305	at most a similar magnitude as the current time (say, within a factor of
		2306	ten). Typical values for offset are, in fact, C<0> or something between
		2307	C<0> and C<interval>, which is also the recommended range.
2040		2308
2041	Note also that there is an upper limit to how often a timer can fire (CPU	2309	Note also that there is an upper limit to how often a timer can fire (CPU
2042	speed for example), so if C<interval> is very small then timing stability	2310	speed for example), so if C<interval> is very small then timing stability
2043	will of course deteriorate. Libev itself tries to be exact to be about one	2311	will of course deteriorate. Libev itself tries to be exact to be about one
2044	millisecond (if the OS supports it and the machine is fast enough).	2312	millisecond (if the OS supports it and the machine is fast enough).
…		…
2074		2342
2075	NOTE: I<< This callback must always return a time that is higher than or	2343	NOTE: I<< This callback must always return a time that is higher than or
2076	equal to the passed C<now> value >>.	2344	equal to the passed C<now> value >>.
2077		2345
2078	This can be used to create very complex timers, such as a timer that	2346	This can be used to create very complex timers, such as a timer that
2079	triggers on "next midnight, local time". To do this, you would calculate the	2347	triggers on "next midnight, local time". To do this, you would calculate
2080	next midnight after C<now> and return the timestamp value for this. How	2348	the next midnight after C<now> and return the timestamp value for
2081	you do this is, again, up to you (but it is not trivial, which is the main	2349	this. Here is a (completely untested, no error checking) example on how to
2082	reason I omitted it as an example).	2350	do this:
		2351
		2352	#include <time.h>
		2353
		2354	static ev_tstamp
		2355	my_rescheduler (ev_periodic *w, ev_tstamp now)
		2356	{
		2357	time_t tnow = (time_t)now;
		2358	struct tm tm;
		2359	localtime_r (&tnow, &tm);
		2360
		2361	tm.tm_sec = tm.tm_min = tm.tm_hour = 0; // midnight current day
		2362	++tm.tm_mday; // midnight next day
		2363
		2364	return mktime (&tm);
		2365	}
		2366
		2367	Note: this code might run into trouble on days that have more then two
		2368	midnights (beginning and end).
2083		2369
2084	=back	2370	=back
2085		2371
2086	=item ev_periodic_again (loop, ev_periodic *)	2372	=item ev_periodic_again (loop, ev_periodic *)
2087		2373
…		…
2152		2438
2153	ev_periodic hourly_tick;	2439	ev_periodic hourly_tick;
2154	ev_periodic_init (&hourly_tick, clock_cb,	2440	ev_periodic_init (&hourly_tick, clock_cb,
2155	fmod (ev_now (loop), 3600.), 3600., 0);	2441	fmod (ev_now (loop), 3600.), 3600., 0);
2156	ev_periodic_start (loop, &hourly_tick);	2442	ev_periodic_start (loop, &hourly_tick);
2157		2443
2158		2444
2159	=head2 C<ev_signal> - signal me when a signal gets signalled!	2445	=head2 C<ev_signal> - signal me when a signal gets signalled!
2160		2446
2161	Signal watchers will trigger an event when the process receives a specific	2447	Signal watchers will trigger an event when the process receives a specific
2162	signal one or more times. Even though signals are very asynchronous, libev	2448	signal one or more times. Even though signals are very asynchronous, libev
2163	will try it's best to deliver signals synchronously, i.e. as part of the	2449	will try its best to deliver signals synchronously, i.e. as part of the
2164	normal event processing, like any other event.	2450	normal event processing, like any other event.
2165		2451
2166	If you want signals to be delivered truly asynchronously, just use	2452	If you want signals to be delivered truly asynchronously, just use
2167	C<sigaction> as you would do without libev and forget about sharing	2453	C<sigaction> as you would do without libev and forget about sharing
2168	the signal. You can even use C<ev_async> from a signal handler to	2454	the signal. You can even use C<ev_async> from a signal handler to
…		…
2172	only within the same loop, i.e. you can watch for C<SIGINT> in your	2458	only within the same loop, i.e. you can watch for C<SIGINT> in your
2173	default loop and for C<SIGIO> in another loop, but you cannot watch for	2459	default loop and for C<SIGIO> in another loop, but you cannot watch for
2174	C<SIGINT> in both the default loop and another loop at the same time. At	2460	C<SIGINT> in both the default loop and another loop at the same time. At
2175	the moment, C<SIGCHLD> is permanently tied to the default loop.	2461	the moment, C<SIGCHLD> is permanently tied to the default loop.
2176		2462
2177	When the first watcher gets started will libev actually register something	2463	Only after the first watcher for a signal is started will libev actually
2178	with the kernel (thus it coexists with your own signal handlers as long as	2464	register something with the kernel. It thus coexists with your own signal
2179	you don't register any with libev for the same signal).	2465	handlers as long as you don't register any with libev for the same signal.
2180		2466
2181	If possible and supported, libev will install its handlers with	2467	If possible and supported, libev will install its handlers with
2182	C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should	2468	C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should
2183	not be unduly interrupted. If you have a problem with system calls getting	2469	not be unduly interrupted. If you have a problem with system calls getting
2184	interrupted by signals you can block all signals in an C<ev_check> watcher	2470	interrupted by signals you can block all signals in an C<ev_check> watcher
…		…
2187	=head3 The special problem of inheritance over fork/execve/pthread_create	2473	=head3 The special problem of inheritance over fork/execve/pthread_create
2188		2474
2189	Both the signal mask (C<sigprocmask>) and the signal disposition	2475	Both the signal mask (C<sigprocmask>) and the signal disposition
2190	(C<sigaction>) are unspecified after starting a signal watcher (and after	2476	(C<sigaction>) are unspecified after starting a signal watcher (and after
2191	stopping it again), that is, libev might or might not block the signal,	2477	stopping it again), that is, libev might or might not block the signal,
2192	and might or might not set or restore the installed signal handler.	2478	and might or might not set or restore the installed signal handler (but
		2479	see C<EVFLAG_NOSIGMASK>).
2193		2480
2194	While this does not matter for the signal disposition (libev never	2481	While this does not matter for the signal disposition (libev never
2195	sets signals to C<SIG_IGN>, so handlers will be reset to C<SIG_DFL> on	2482	sets signals to C<SIG_IGN>, so handlers will be reset to C<SIG_DFL> on
2196	C<execve>), this matters for the signal mask: many programs do not expect	2483	C<execve>), this matters for the signal mask: many programs do not expect
2197	certain signals to be blocked.	2484	certain signals to be blocked.
…		…
2211		2498
2212	So I can't stress this enough: I<If you do not reset your signal mask when	2499	So I can't stress this enough: I<If you do not reset your signal mask when
2213	you expect it to be empty, you have a race condition in your code>. This	2500	you expect it to be empty, you have a race condition in your code>. This
2214	is not a libev-specific thing, this is true for most event libraries.	2501	is not a libev-specific thing, this is true for most event libraries.
2215		2502
		2503	=head3 The special problem of threads signal handling
		2504
		2505	POSIX threads has problematic signal handling semantics, specifically,
		2506	a lot of functionality (sigfd, sigwait etc.) only really works if all
		2507	threads in a process block signals, which is hard to achieve.
		2508
		2509	When you want to use sigwait (or mix libev signal handling with your own
		2510	for the same signals), you can tackle this problem by globally blocking
		2511	all signals before creating any threads (or creating them with a fully set
		2512	sigprocmask) and also specifying the C<EVFLAG_NOSIGMASK> when creating
		2513	loops. Then designate one thread as "signal receiver thread" which handles
		2514	these signals. You can pass on any signals that libev might be interested
		2515	in by calling C<ev_feed_signal>.
		2516
2216	=head3 Watcher-Specific Functions and Data Members	2517	=head3 Watcher-Specific Functions and Data Members
2217		2518
2218	=over 4	2519	=over 4
2219		2520
2220	=item ev_signal_init (ev_signal *, callback, int signum)	2521	=item ev_signal_init (ev_signal *, callback, int signum)
…		…
2235	Example: Try to exit cleanly on SIGINT.	2536	Example: Try to exit cleanly on SIGINT.
2236		2537
2237	static void	2538	static void
2238	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)	2539	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)
2239	{	2540	{
2240	ev_unloop (loop, EVUNLOOP_ALL);	2541	ev_break (loop, EVBREAK_ALL);
2241	}	2542	}
2242		2543
2243	ev_signal signal_watcher;	2544	ev_signal signal_watcher;
2244	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	2545	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
2245	ev_signal_start (loop, &signal_watcher);	2546	ev_signal_start (loop, &signal_watcher);
…		…
2354		2655
2355	=head2 C<ev_stat> - did the file attributes just change?	2656	=head2 C<ev_stat> - did the file attributes just change?
2356		2657
2357	This watches a file system path for attribute changes. That is, it calls	2658	This watches a file system path for attribute changes. That is, it calls
2358	C<stat> on that path in regular intervals (or when the OS says it changed)	2659	C<stat> on that path in regular intervals (or when the OS says it changed)
2359	and sees if it changed compared to the last time, invoking the callback if	2660	and sees if it changed compared to the last time, invoking the callback
2360	it did.	2661	if it did. Starting the watcher C<stat>'s the file, so only changes that
		2662	happen after the watcher has been started will be reported.
2361		2663
2362	The path does not need to exist: changing from "path exists" to "path does	2664	The path does not need to exist: changing from "path exists" to "path does
2363	not exist" is a status change like any other. The condition "path does not	2665	not exist" is a status change like any other. The condition "path does not
2364	exist" (or more correctly "path cannot be stat'ed") is signified by the	2666	exist" (or more correctly "path cannot be stat'ed") is signified by the
2365	C<st_nlink> field being zero (which is otherwise always forced to be at	2667	C<st_nlink> field being zero (which is otherwise always forced to be at
…		…
2595	Apart from keeping your process non-blocking (which is a useful	2897	Apart from keeping your process non-blocking (which is a useful
2596	effect on its own sometimes), idle watchers are a good place to do	2898	effect on its own sometimes), idle watchers are a good place to do
2597	"pseudo-background processing", or delay processing stuff to after the	2899	"pseudo-background processing", or delay processing stuff to after the
2598	event loop has handled all outstanding events.	2900	event loop has handled all outstanding events.
2599		2901
		2902	=head3 Abusing an C<ev_idle> watcher for its side-effect
		2903
		2904	As long as there is at least one active idle watcher, libev will never
		2905	sleep unnecessarily. Or in other words, it will loop as fast as possible.
		2906	For this to work, the idle watcher doesn't need to be invoked at all - the
		2907	lowest priority will do.
		2908
		2909	This mode of operation can be useful together with an C<ev_check> watcher,
		2910	to do something on each event loop iteration - for example to balance load
		2911	between different connections.
		2912
		2913	See L</Abusing an ev_check watcher for its side-effect> for a longer
		2914	example.
		2915
2600	=head3 Watcher-Specific Functions and Data Members	2916	=head3 Watcher-Specific Functions and Data Members
2601		2917
2602	=over 4	2918	=over 4
2603		2919
2604	=item ev_idle_init (ev_idle *, callback)	2920	=item ev_idle_init (ev_idle *, callback)
…		…
2615	callback, free it. Also, use no error checking, as usual.	2931	callback, free it. Also, use no error checking, as usual.
2616		2932
2617	static void	2933	static void
2618	idle_cb (struct ev_loop *loop, ev_idle *w, int revents)	2934	idle_cb (struct ev_loop *loop, ev_idle *w, int revents)
2619	{	2935	{
		2936	// stop the watcher
		2937	ev_idle_stop (loop, w);
		2938
		2939	// now we can free it
2620	free (w);	2940	free (w);
		2941
2621	// now do something you wanted to do when the program has	2942	// now do something you wanted to do when the program has
2622	// no longer anything immediate to do.	2943	// no longer anything immediate to do.
2623	}	2944	}
2624		2945
2625	ev_idle *idle_watcher = malloc (sizeof (ev_idle));	2946	ev_idle *idle_watcher = malloc (sizeof (ev_idle));
…		…
2627	ev_idle_start (loop, idle_watcher);	2948	ev_idle_start (loop, idle_watcher);
2628		2949
2629		2950
2630	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!	2951	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!
2631		2952
2632	Prepare and check watchers are usually (but not always) used in pairs:	2953	Prepare and check watchers are often (but not always) used in pairs:
2633	prepare watchers get invoked before the process blocks and check watchers	2954	prepare watchers get invoked before the process blocks and check watchers
2634	afterwards.	2955	afterwards.
2635		2956
2636	You I<must not> call C<ev_loop> or similar functions that enter	2957	You I<must not> call C<ev_run> (or similar functions that enter the
2637	the current event loop from either C<ev_prepare> or C<ev_check>	2958	current event loop) or C<ev_loop_fork> from either C<ev_prepare> or
2638	watchers. Other loops than the current one are fine, however. The	2959	C<ev_check> watchers. Other loops than the current one are fine,
2639	rationale behind this is that you do not need to check for recursion in	2960	however. The rationale behind this is that you do not need to check
2640	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,	2961	for recursion in those watchers, i.e. the sequence will always be
2641	C<ev_check> so if you have one watcher of each kind they will always be	2962	C<ev_prepare>, blocking, C<ev_check> so if you have one watcher of each
2642	called in pairs bracketing the blocking call.	2963	kind they will always be called in pairs bracketing the blocking call.
2643		2964
2644	Their main purpose is to integrate other event mechanisms into libev and	2965	Their main purpose is to integrate other event mechanisms into libev and
2645	their use is somewhat advanced. They could be used, for example, to track	2966	their use is somewhat advanced. They could be used, for example, to track
2646	variable changes, implement your own watchers, integrate net-snmp or a	2967	variable changes, implement your own watchers, integrate net-snmp or a
2647	coroutine library and lots more. They are also occasionally useful if	2968	coroutine library and lots more. They are also occasionally useful if
…		…
2665	with priority higher than or equal to the event loop and one coroutine	2986	with priority higher than or equal to the event loop and one coroutine
2666	of lower priority, but only once, using idle watchers to keep the event	2987	of lower priority, but only once, using idle watchers to keep the event
2667	loop from blocking if lower-priority coroutines are active, thus mapping	2988	loop from blocking if lower-priority coroutines are active, thus mapping
2668	low-priority coroutines to idle/background tasks).	2989	low-priority coroutines to idle/background tasks).
2669		2990
2670	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)	2991	When used for this purpose, it is recommended to give C<ev_check> watchers
2671	priority, to ensure that they are being run before any other watchers	2992	highest (C<EV_MAXPRI>) priority, to ensure that they are being run before
2672	after the poll (this doesn't matter for C<ev_prepare> watchers).	2993	any other watchers after the poll (this doesn't matter for C<ev_prepare>
		2994	watchers).
2673		2995
2674	Also, C<ev_check> watchers (and C<ev_prepare> watchers, too) should not	2996	Also, C<ev_check> watchers (and C<ev_prepare> watchers, too) should not
2675	activate ("feed") events into libev. While libev fully supports this, they	2997	activate ("feed") events into libev. While libev fully supports this, they
2676	might get executed before other C<ev_check> watchers did their job. As	2998	might get executed before other C<ev_check> watchers did their job. As
2677	C<ev_check> watchers are often used to embed other (non-libev) event	2999	C<ev_check> watchers are often used to embed other (non-libev) event
2678	loops those other event loops might be in an unusable state until their	3000	loops those other event loops might be in an unusable state until their
2679	C<ev_check> watcher ran (always remind yourself to coexist peacefully with	3001	C<ev_check> watcher ran (always remind yourself to coexist peacefully with
2680	others).	3002	others).
		3003
		3004	=head3 Abusing an C<ev_check> watcher for its side-effect
		3005
		3006	C<ev_check> (and less often also C<ev_prepare>) watchers can also be
		3007	useful because they are called once per event loop iteration. For
		3008	example, if you want to handle a large number of connections fairly, you
		3009	normally only do a bit of work for each active connection, and if there
		3010	is more work to do, you wait for the next event loop iteration, so other
		3011	connections have a chance of making progress.
		3012
		3013	Using an C<ev_check> watcher is almost enough: it will be called on the
		3014	next event loop iteration. However, that isn't as soon as possible -
		3015	without external events, your C<ev_check> watcher will not be invoked.
		3016
		3017	This is where C<ev_idle> watchers come in handy - all you need is a
		3018	single global idle watcher that is active as long as you have one active
		3019	C<ev_check> watcher. The C<ev_idle> watcher makes sure the event loop
		3020	will not sleep, and the C<ev_check> watcher makes sure a callback gets
		3021	invoked. Neither watcher alone can do that.
2681		3022
2682	=head3 Watcher-Specific Functions and Data Members	3023	=head3 Watcher-Specific Functions and Data Members
2683		3024
2684	=over 4	3025	=over 4
2685		3026
…		…
2809		3150
2810	if (timeout >= 0)	3151	if (timeout >= 0)
2811	// create/start timer	3152	// create/start timer
2812		3153
2813	// poll	3154	// poll
2814	ev_loop (EV_A_ 0);	3155	ev_run (EV_A_ 0);
2815		3156
2816	// stop timer again	3157	// stop timer again
2817	if (timeout >= 0)	3158	if (timeout >= 0)
2818	ev_timer_stop (EV_A_ &to);	3159	ev_timer_stop (EV_A_ &to);
2819		3160
…		…
2886		3227
2887	=over 4	3228	=over 4
2888		3229
2889	=item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)	3230	=item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)
2890		3231
2891	=item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)	3232	=item ev_embed_set (ev_embed *, struct ev_loop *embedded_loop)
2892		3233
2893	Configures the watcher to embed the given loop, which must be	3234	Configures the watcher to embed the given loop, which must be
2894	embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be	3235	embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be
2895	invoked automatically, otherwise it is the responsibility of the callback	3236	invoked automatically, otherwise it is the responsibility of the callback
2896	to invoke it (it will continue to be called until the sweep has been done,	3237	to invoke it (it will continue to be called until the sweep has been done,
2897	if you do not want that, you need to temporarily stop the embed watcher).	3238	if you do not want that, you need to temporarily stop the embed watcher).
2898		3239
2899	=item ev_embed_sweep (loop, ev_embed *)	3240	=item ev_embed_sweep (loop, ev_embed *)
2900		3241
2901	Make a single, non-blocking sweep over the embedded loop. This works	3242	Make a single, non-blocking sweep over the embedded loop. This works
2902	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	3243	similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most
2903	appropriate way for embedded loops.	3244	appropriate way for embedded loops.
2904		3245
2905	=item struct ev_loop *other [read-only]	3246	=item struct ev_loop *other [read-only]
2906		3247
2907	The embedded event loop.	3248	The embedded event loop.
…		…
2917	used).	3258	used).
2918		3259
2919	struct ev_loop *loop_hi = ev_default_init (0);	3260	struct ev_loop *loop_hi = ev_default_init (0);
2920	struct ev_loop *loop_lo = 0;	3261	struct ev_loop *loop_lo = 0;
2921	ev_embed embed;	3262	ev_embed embed;
2922		3263
2923	// see if there is a chance of getting one that works	3264	// see if there is a chance of getting one that works
2924	// (remember that a flags value of 0 means autodetection)	3265	// (remember that a flags value of 0 means autodetection)
2925	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()	3266	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()
2926	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())	3267	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())
2927	: 0;	3268	: 0;
…		…
2941	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).	3282	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).
2942		3283
2943	struct ev_loop *loop = ev_default_init (0);	3284	struct ev_loop *loop = ev_default_init (0);
2944	struct ev_loop *loop_socket = 0;	3285	struct ev_loop *loop_socket = 0;
2945	ev_embed embed;	3286	ev_embed embed;
2946		3287
2947	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)	3288	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)
2948	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))	3289	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))
2949	{	3290	{
2950	ev_embed_init (&embed, 0, loop_socket);	3291	ev_embed_init (&embed, 0, loop_socket);
2951	ev_embed_start (loop, &embed);	3292	ev_embed_start (loop, &embed);
…		…
2959		3300
2960	=head2 C<ev_fork> - the audacity to resume the event loop after a fork	3301	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
2961		3302
2962	Fork watchers are called when a C<fork ()> was detected (usually because	3303	Fork watchers are called when a C<fork ()> was detected (usually because
2963	whoever is a good citizen cared to tell libev about it by calling	3304	whoever is a good citizen cared to tell libev about it by calling
2964	C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the	3305	C<ev_loop_fork>). The invocation is done before the event loop blocks next
2965	event loop blocks next and before C<ev_check> watchers are being called,	3306	and before C<ev_check> watchers are being called, and only in the child
2966	and only in the child after the fork. If whoever good citizen calling	3307	after the fork. If whoever good citizen calling C<ev_default_fork> cheats
2967	C<ev_default_fork> cheats and calls it in the wrong process, the fork	3308	and calls it in the wrong process, the fork handlers will be invoked, too,
2968	handlers will be invoked, too, of course.	3309	of course.
2969		3310
2970	=head3 The special problem of life after fork - how is it possible?	3311	=head3 The special problem of life after fork - how is it possible?
2971		3312
2972	Most uses of C<fork()> consist of forking, then some simple calls to set	3313	Most uses of C<fork ()> consist of forking, then some simple calls to set
2973	up/change the process environment, followed by a call to C<exec()>. This	3314	up/change the process environment, followed by a call to C<exec()>. This
2974	sequence should be handled by libev without any problems.	3315	sequence should be handled by libev without any problems.
2975		3316
2976	This changes when the application actually wants to do event handling	3317	This changes when the application actually wants to do event handling
2977	in the child, or both parent in child, in effect "continuing" after the	3318	in the child, or both parent in child, in effect "continuing" after the
…		…
2993	disadvantage of having to use multiple event loops (which do not support	3334	disadvantage of having to use multiple event loops (which do not support
2994	signal watchers).	3335	signal watchers).
2995		3336
2996	When this is not possible, or you want to use the default loop for	3337	When this is not possible, or you want to use the default loop for
2997	other reasons, then in the process that wants to start "fresh", call	3338	other reasons, then in the process that wants to start "fresh", call
2998	C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying	3339	C<ev_loop_destroy (EV_DEFAULT)> followed by C<ev_default_loop (...)>.
2999	the default loop will "orphan" (not stop) all registered watchers, so you	3340	Destroying the default loop will "orphan" (not stop) all registered
3000	have to be careful not to execute code that modifies those watchers. Note	3341	watchers, so you have to be careful not to execute code that modifies
3001	also that in that case, you have to re-register any signal watchers.	3342	those watchers. Note also that in that case, you have to re-register any
		3343	signal watchers.
3002		3344
3003	=head3 Watcher-Specific Functions and Data Members	3345	=head3 Watcher-Specific Functions and Data Members
3004		3346
3005	=over 4	3347	=over 4
3006		3348
3007	=item ev_fork_init (ev_signal *, callback)	3349	=item ev_fork_init (ev_fork *, callback)
3008		3350
3009	Initialises and configures the fork watcher - it has no parameters of any	3351	Initialises and configures the fork watcher - it has no parameters of any
3010	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,	3352	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
3011	believe me.	3353	really.
3012		3354
3013	=back	3355	=back
		3356
		3357
		3358	=head2 C<ev_cleanup> - even the best things end
		3359
		3360	Cleanup watchers are called just before the event loop is being destroyed
		3361	by a call to C<ev_loop_destroy>.
		3362
		3363	While there is no guarantee that the event loop gets destroyed, cleanup
		3364	watchers provide a convenient method to install cleanup hooks for your
		3365	program, worker threads and so on - you just to make sure to destroy the
		3366	loop when you want them to be invoked.
		3367
		3368	Cleanup watchers are invoked in the same way as any other watcher. Unlike
		3369	all other watchers, they do not keep a reference to the event loop (which
		3370	makes a lot of sense if you think about it). Like all other watchers, you
		3371	can call libev functions in the callback, except C<ev_cleanup_start>.
		3372
		3373	=head3 Watcher-Specific Functions and Data Members
		3374
		3375	=over 4
		3376
		3377	=item ev_cleanup_init (ev_cleanup *, callback)
		3378
		3379	Initialises and configures the cleanup watcher - it has no parameters of
		3380	any kind. There is a C<ev_cleanup_set> macro, but using it is utterly
		3381	pointless, I assure you.
		3382
		3383	=back
		3384
		3385	Example: Register an atexit handler to destroy the default loop, so any
		3386	cleanup functions are called.
		3387
		3388	static void
		3389	program_exits (void)
		3390	{
		3391	ev_loop_destroy (EV_DEFAULT_UC);
		3392	}
		3393
		3394	...
		3395	atexit (program_exits);
3014		3396
3015		3397
3016	=head2 C<ev_async> - how to wake up an event loop	3398	=head2 C<ev_async> - how to wake up an event loop
3017		3399
3018	In general, you cannot use an C<ev_loop> from multiple threads or other	3400	In general, you cannot use an C<ev_loop> from multiple threads or other
…		…
3025	it by calling C<ev_async_send>, which is thread- and signal safe.	3407	it by calling C<ev_async_send>, which is thread- and signal safe.
3026		3408
3027	This functionality is very similar to C<ev_signal> watchers, as signals,	3409	This functionality is very similar to C<ev_signal> watchers, as signals,
3028	too, are asynchronous in nature, and signals, too, will be compressed	3410	too, are asynchronous in nature, and signals, too, will be compressed
3029	(i.e. the number of callback invocations may be less than the number of	3411	(i.e. the number of callback invocations may be less than the number of
3030	C<ev_async_sent> calls).	3412	C<ev_async_send> calls). In fact, you could use signal watchers as a kind
3031		3413	of "global async watchers" by using a watcher on an otherwise unused
3032	Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not	3414	signal, and C<ev_feed_signal> to signal this watcher from another thread,
3033	just the default loop.	3415	even without knowing which loop owns the signal.
3034		3416
3035	=head3 Queueing	3417	=head3 Queueing
3036		3418
3037	C<ev_async> does not support queueing of data in any way. The reason	3419	C<ev_async> does not support queueing of data in any way. The reason
3038	is that the author does not know of a simple (or any) algorithm for a	3420	is that the author does not know of a simple (or any) algorithm for a
…		…
3130	trust me.	3512	trust me.
3131		3513
3132	=item ev_async_send (loop, ev_async *)	3514	=item ev_async_send (loop, ev_async *)
3133		3515
3134	Sends/signals/activates the given C<ev_async> watcher, that is, feeds	3516	Sends/signals/activates the given C<ev_async> watcher, that is, feeds
3135	an C<EV_ASYNC> event on the watcher into the event loop. Unlike	3517	an C<EV_ASYNC> event on the watcher into the event loop, and instantly
		3518	returns.
		3519
3136	C<ev_feed_event>, this call is safe to do from other threads, signal or	3520	Unlike C<ev_feed_event>, this call is safe to do from other threads,
3137	similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding	3521	signal or similar contexts (see the discussion of C<EV_ATOMIC_T> in the
3138	section below on what exactly this means).	3522	embedding section below on what exactly this means).
3139		3523
3140	Note that, as with other watchers in libev, multiple events might get	3524	Note that, as with other watchers in libev, multiple events might get
3141	compressed into a single callback invocation (another way to look at this	3525	compressed into a single callback invocation (another way to look at
3142	is that C<ev_async> watchers are level-triggered, set on C<ev_async_send>,	3526	this is that C<ev_async> watchers are level-triggered: they are set on
3143	reset when the event loop detects that).	3527	C<ev_async_send>, reset when the event loop detects that).
3144		3528
3145	This call incurs the overhead of a system call only once per event loop	3529	This call incurs the overhead of at most one extra system call per event
3146	iteration, so while the overhead might be noticeable, it doesn't apply to	3530	loop iteration, if the event loop is blocked, and no syscall at all if
3147	repeated calls to C<ev_async_send> for the same event loop.	3531	the event loop (or your program) is processing events. That means that
		3532	repeated calls are basically free (there is no need to avoid calls for
		3533	performance reasons) and that the overhead becomes smaller (typically
		3534	zero) under load.
3148		3535
3149	=item bool = ev_async_pending (ev_async *)	3536	=item bool = ev_async_pending (ev_async *)
3150		3537
3151	Returns a non-zero value when C<ev_async_send> has been called on the	3538	Returns a non-zero value when C<ev_async_send> has been called on the
3152	watcher but the event has not yet been processed (or even noted) by the	3539	watcher but the event has not yet been processed (or even noted) by the
…		…
3169		3556
3170	There are some other functions of possible interest. Described. Here. Now.	3557	There are some other functions of possible interest. Described. Here. Now.
3171		3558
3172	=over 4	3559	=over 4
3173		3560
3174	=item ev_once (loop, int fd, int events, ev_tstamp timeout, callback)	3561	=item ev_once (loop, int fd, int events, ev_tstamp timeout, callback, arg)
3175		3562
3176	This function combines a simple timer and an I/O watcher, calls your	3563	This function combines a simple timer and an I/O watcher, calls your
3177	callback on whichever event happens first and automatically stops both	3564	callback on whichever event happens first and automatically stops both
3178	watchers. This is useful if you want to wait for a single event on an fd	3565	watchers. This is useful if you want to wait for a single event on an fd
3179	or timeout without having to allocate/configure/start/stop/free one or	3566	or timeout without having to allocate/configure/start/stop/free one or
…		…
3207	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	3594	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
3208		3595
3209	=item ev_feed_fd_event (loop, int fd, int revents)	3596	=item ev_feed_fd_event (loop, int fd, int revents)
3210		3597
3211	Feed an event on the given fd, as if a file descriptor backend detected	3598	Feed an event on the given fd, as if a file descriptor backend detected
3212	the given events it.	3599	the given events.
3213		3600
3214	=item ev_feed_signal_event (loop, int signum)	3601	=item ev_feed_signal_event (loop, int signum)
3215		3602
3216	Feed an event as if the given signal occurred (C<loop> must be the default	3603	Feed an event as if the given signal occurred. See also C<ev_feed_signal>,
3217	loop!).	3604	which is async-safe.
3218		3605
3219	=back	3606	=back
		3607
		3608
		3609	=head1 COMMON OR USEFUL IDIOMS (OR BOTH)
		3610
		3611	This section explains some common idioms that are not immediately
		3612	obvious. Note that examples are sprinkled over the whole manual, and this
		3613	section only contains stuff that wouldn't fit anywhere else.
		3614
		3615	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
		3616
		3617	Each watcher has, by default, a C<void *data> member that you can read
		3618	or modify at any time: libev will completely ignore it. This can be used
		3619	to associate arbitrary data with your watcher. If you need more data and
		3620	don't want to allocate memory separately and store a pointer to it in that
		3621	data member, you can also "subclass" the watcher type and provide your own
		3622	data:
		3623
		3624	struct my_io
		3625	{
		3626	ev_io io;
		3627	int otherfd;
		3628	void *somedata;
		3629	struct whatever *mostinteresting;
		3630	};
		3631
		3632	...
		3633	struct my_io w;
		3634	ev_io_init (&w.io, my_cb, fd, EV_READ);
		3635
		3636	And since your callback will be called with a pointer to the watcher, you
		3637	can cast it back to your own type:
		3638
		3639	static void my_cb (struct ev_loop *loop, ev_io *w_, int revents)
		3640	{
		3641	struct my_io *w = (struct my_io *)w_;
		3642	...
		3643	}
		3644
		3645	More interesting and less C-conformant ways of casting your callback
		3646	function type instead have been omitted.
		3647
		3648	=head2 BUILDING YOUR OWN COMPOSITE WATCHERS
		3649
		3650	Another common scenario is to use some data structure with multiple
		3651	embedded watchers, in effect creating your own watcher that combines
		3652	multiple libev event sources into one "super-watcher":
		3653
		3654	struct my_biggy
		3655	{
		3656	int some_data;
		3657	ev_timer t1;
		3658	ev_timer t2;
		3659	}
		3660
		3661	In this case getting the pointer to C<my_biggy> is a bit more
		3662	complicated: Either you store the address of your C<my_biggy> struct in
		3663	the C<data> member of the watcher (for woozies or C++ coders), or you need
		3664	to use some pointer arithmetic using C<offsetof> inside your watchers (for
		3665	real programmers):
		3666
		3667	#include <stddef.h>
		3668
		3669	static void
		3670	t1_cb (EV_P_ ev_timer *w, int revents)
		3671	{
		3672	struct my_biggy big = (struct my_biggy *)
		3673	(((char *)w) - offsetof (struct my_biggy, t1));
		3674	}
		3675
		3676	static void
		3677	t2_cb (EV_P_ ev_timer *w, int revents)
		3678	{
		3679	struct my_biggy big = (struct my_biggy *)
		3680	(((char *)w) - offsetof (struct my_biggy, t2));
		3681	}
		3682
		3683	=head2 AVOIDING FINISHING BEFORE RETURNING
		3684
		3685	Often you have structures like this in event-based programs:
		3686
		3687	callback ()
		3688	{
		3689	free (request);
		3690	}
		3691
		3692	request = start_new_request (..., callback);
		3693
		3694	The intent is to start some "lengthy" operation. The C<request> could be
		3695	used to cancel the operation, or do other things with it.
		3696
		3697	It's not uncommon to have code paths in C<start_new_request> that
		3698	immediately invoke the callback, for example, to report errors. Or you add
		3699	some caching layer that finds that it can skip the lengthy aspects of the
		3700	operation and simply invoke the callback with the result.
		3701
		3702	The problem here is that this will happen I<before> C<start_new_request>
		3703	has returned, so C<request> is not set.
		3704
		3705	Even if you pass the request by some safer means to the callback, you
		3706	might want to do something to the request after starting it, such as
		3707	canceling it, which probably isn't working so well when the callback has
		3708	already been invoked.
		3709
		3710	A common way around all these issues is to make sure that
		3711	C<start_new_request> I<always> returns before the callback is invoked. If
		3712	C<start_new_request> immediately knows the result, it can artificially
		3713	delay invoking the callback by using a C<prepare> or C<idle> watcher for
		3714	example, or more sneakily, by reusing an existing (stopped) watcher and
		3715	pushing it into the pending queue:
		3716
		3717	ev_set_cb (watcher, callback);
		3718	ev_feed_event (EV_A_ watcher, 0);
		3719
		3720	This way, C<start_new_request> can safely return before the callback is
		3721	invoked, while not delaying callback invocation too much.
		3722
		3723	=head2 MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS
		3724
		3725	Often (especially in GUI toolkits) there are places where you have
		3726	I<modal> interaction, which is most easily implemented by recursively
		3727	invoking C<ev_run>.
		3728
		3729	This brings the problem of exiting - a callback might want to finish the
		3730	main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but
		3731	a modal "Are you sure?" dialog is still waiting), or just the nested one
		3732	and not the main one (e.g. user clocked "Ok" in a modal dialog), or some
		3733	other combination: In these cases, a simple C<ev_break> will not work.
		3734
		3735	The solution is to maintain "break this loop" variable for each C<ev_run>
		3736	invocation, and use a loop around C<ev_run> until the condition is
		3737	triggered, using C<EVRUN_ONCE>:
		3738
		3739	// main loop
		3740	int exit_main_loop = 0;
		3741
		3742	while (!exit_main_loop)
		3743	ev_run (EV_DEFAULT_ EVRUN_ONCE);
		3744
		3745	// in a modal watcher
		3746	int exit_nested_loop = 0;
		3747
		3748	while (!exit_nested_loop)
		3749	ev_run (EV_A_ EVRUN_ONCE);
		3750
		3751	To exit from any of these loops, just set the corresponding exit variable:
		3752
		3753	// exit modal loop
		3754	exit_nested_loop = 1;
		3755
		3756	// exit main program, after modal loop is finished
		3757	exit_main_loop = 1;
		3758
		3759	// exit both
		3760	exit_main_loop = exit_nested_loop = 1;
		3761
		3762	=head2 THREAD LOCKING EXAMPLE
		3763
		3764	Here is a fictitious example of how to run an event loop in a different
		3765	thread from where callbacks are being invoked and watchers are
		3766	created/added/removed.
		3767
		3768	For a real-world example, see the C<EV::Loop::Async> perl module,
		3769	which uses exactly this technique (which is suited for many high-level
		3770	languages).
		3771
		3772	The example uses a pthread mutex to protect the loop data, a condition
		3773	variable to wait for callback invocations, an async watcher to notify the
		3774	event loop thread and an unspecified mechanism to wake up the main thread.
		3775
		3776	First, you need to associate some data with the event loop:
		3777
		3778	typedef struct {
		3779	mutex_t lock; /* global loop lock */
		3780	ev_async async_w;
		3781	thread_t tid;
		3782	cond_t invoke_cv;
		3783	} userdata;
		3784
		3785	void prepare_loop (EV_P)
		3786	{
		3787	// for simplicity, we use a static userdata struct.
		3788	static userdata u;
		3789
		3790	ev_async_init (&u->async_w, async_cb);
		3791	ev_async_start (EV_A_ &u->async_w);
		3792
		3793	pthread_mutex_init (&u->lock, 0);
		3794	pthread_cond_init (&u->invoke_cv, 0);
		3795
		3796	// now associate this with the loop
		3797	ev_set_userdata (EV_A_ u);
		3798	ev_set_invoke_pending_cb (EV_A_ l_invoke);
		3799	ev_set_loop_release_cb (EV_A_ l_release, l_acquire);
		3800
		3801	// then create the thread running ev_run
		3802	pthread_create (&u->tid, 0, l_run, EV_A);
		3803	}
		3804
		3805	The callback for the C<ev_async> watcher does nothing: the watcher is used
		3806	solely to wake up the event loop so it takes notice of any new watchers
		3807	that might have been added:
		3808
		3809	static void
		3810	async_cb (EV_P_ ev_async *w, int revents)
		3811	{
		3812	// just used for the side effects
		3813	}
		3814
		3815	The C<l_release> and C<l_acquire> callbacks simply unlock/lock the mutex
		3816	protecting the loop data, respectively.
		3817
		3818	static void
		3819	l_release (EV_P)
		3820	{
		3821	userdata *u = ev_userdata (EV_A);
		3822	pthread_mutex_unlock (&u->lock);
		3823	}
		3824
		3825	static void
		3826	l_acquire (EV_P)
		3827	{
		3828	userdata *u = ev_userdata (EV_A);
		3829	pthread_mutex_lock (&u->lock);
		3830	}
		3831
		3832	The event loop thread first acquires the mutex, and then jumps straight
		3833	into C<ev_run>:
		3834
		3835	void *
		3836	l_run (void *thr_arg)
		3837	{
		3838	struct ev_loop *loop = (struct ev_loop *)thr_arg;
		3839
		3840	l_acquire (EV_A);
		3841	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
		3842	ev_run (EV_A_ 0);
		3843	l_release (EV_A);
		3844
		3845	return 0;
		3846	}
		3847
		3848	Instead of invoking all pending watchers, the C<l_invoke> callback will
		3849	signal the main thread via some unspecified mechanism (signals? pipe
		3850	writes? C<Async::Interrupt>?) and then waits until all pending watchers
		3851	have been called (in a while loop because a) spurious wakeups are possible
		3852	and b) skipping inter-thread-communication when there are no pending
		3853	watchers is very beneficial):
		3854
		3855	static void
		3856	l_invoke (EV_P)
		3857	{
		3858	userdata *u = ev_userdata (EV_A);
		3859
		3860	while (ev_pending_count (EV_A))
		3861	{
		3862	wake_up_other_thread_in_some_magic_or_not_so_magic_way ();
		3863	pthread_cond_wait (&u->invoke_cv, &u->lock);
		3864	}
		3865	}
		3866
		3867	Now, whenever the main thread gets told to invoke pending watchers, it
		3868	will grab the lock, call C<ev_invoke_pending> and then signal the loop
		3869	thread to continue:
		3870
		3871	static void
		3872	real_invoke_pending (EV_P)
		3873	{
		3874	userdata *u = ev_userdata (EV_A);
		3875
		3876	pthread_mutex_lock (&u->lock);
		3877	ev_invoke_pending (EV_A);
		3878	pthread_cond_signal (&u->invoke_cv);
		3879	pthread_mutex_unlock (&u->lock);
		3880	}
		3881
		3882	Whenever you want to start/stop a watcher or do other modifications to an
		3883	event loop, you will now have to lock:
		3884
		3885	ev_timer timeout_watcher;
		3886	userdata *u = ev_userdata (EV_A);
		3887
		3888	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
		3889
		3890	pthread_mutex_lock (&u->lock);
		3891	ev_timer_start (EV_A_ &timeout_watcher);
		3892	ev_async_send (EV_A_ &u->async_w);
		3893	pthread_mutex_unlock (&u->lock);
		3894
		3895	Note that sending the C<ev_async> watcher is required because otherwise
		3896	an event loop currently blocking in the kernel will have no knowledge
		3897	about the newly added timer. By waking up the loop it will pick up any new
		3898	watchers in the next event loop iteration.
		3899
		3900	=head2 THREADS, COROUTINES, CONTINUATIONS, QUEUES... INSTEAD OF CALLBACKS
		3901
		3902	While the overhead of a callback that e.g. schedules a thread is small, it
		3903	is still an overhead. If you embed libev, and your main usage is with some
		3904	kind of threads or coroutines, you might want to customise libev so that
		3905	doesn't need callbacks anymore.
		3906
		3907	Imagine you have coroutines that you can switch to using a function
		3908	C<switch_to (coro)>, that libev runs in a coroutine called C<libev_coro>
		3909	and that due to some magic, the currently active coroutine is stored in a
		3910	global called C<current_coro>. Then you can build your own "wait for libev
		3911	event" primitive by changing C<EV_CB_DECLARE> and C<EV_CB_INVOKE> (note
		3912	the differing C<;> conventions):
		3913
		3914	#define EV_CB_DECLARE(type) struct my_coro *cb;
		3915	#define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb)
		3916
		3917	That means instead of having a C callback function, you store the
		3918	coroutine to switch to in each watcher, and instead of having libev call
		3919	your callback, you instead have it switch to that coroutine.
		3920
		3921	A coroutine might now wait for an event with a function called
		3922	C<wait_for_event>. (the watcher needs to be started, as always, but it doesn't
		3923	matter when, or whether the watcher is active or not when this function is
		3924	called):
		3925
		3926	void
		3927	wait_for_event (ev_watcher *w)
		3928	{
		3929	ev_set_cb (w, current_coro);
		3930	switch_to (libev_coro);
		3931	}
		3932
		3933	That basically suspends the coroutine inside C<wait_for_event> and
		3934	continues the libev coroutine, which, when appropriate, switches back to
		3935	this or any other coroutine.
		3936
		3937	You can do similar tricks if you have, say, threads with an event queue -
		3938	instead of storing a coroutine, you store the queue object and instead of
		3939	switching to a coroutine, you push the watcher onto the queue and notify
		3940	any waiters.
		3941
		3942	To embed libev, see L</EMBEDDING>, but in short, it's easiest to create two
		3943	files, F<my_ev.h> and F<my_ev.c> that include the respective libev files:
		3944
		3945	// my_ev.h
		3946	#define EV_CB_DECLARE(type) struct my_coro *cb;
		3947	#define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb)
		3948	#include "../libev/ev.h"
		3949
		3950	// my_ev.c
		3951	#define EV_H "my_ev.h"
		3952	#include "../libev/ev.c"
		3953
		3954	And then use F<my_ev.h> when you would normally use F<ev.h>, and compile
		3955	F<my_ev.c> into your project. When properly specifying include paths, you
		3956	can even use F<ev.h> as header file name directly.
3220		3957
3221		3958
3222	=head1 LIBEVENT EMULATION	3959	=head1 LIBEVENT EMULATION
3223		3960
3224	Libev offers a compatibility emulation layer for libevent. It cannot	3961	Libev offers a compatibility emulation layer for libevent. It cannot
3225	emulate the internals of libevent, so here are some usage hints:	3962	emulate the internals of libevent, so here are some usage hints:
3226		3963
3227	=over 4	3964	=over 4
		3965
		3966	=item * Only the libevent-1.4.1-beta API is being emulated.
		3967
		3968	This was the newest libevent version available when libev was implemented,
		3969	and is still mostly unchanged in 2010.
3228		3970
3229	=item * Use it by including <event.h>, as usual.	3971	=item * Use it by including <event.h>, as usual.
3230		3972
3231	=item * The following members are fully supported: ev_base, ev_callback,	3973	=item * The following members are fully supported: ev_base, ev_callback,
3232	ev_arg, ev_fd, ev_res, ev_events.	3974	ev_arg, ev_fd, ev_res, ev_events.
…		…
3238	=item * Priorities are not currently supported. Initialising priorities	3980	=item * Priorities are not currently supported. Initialising priorities
3239	will fail and all watchers will have the same priority, even though there	3981	will fail and all watchers will have the same priority, even though there
3240	is an ev_pri field.	3982	is an ev_pri field.
3241		3983
3242	=item * In libevent, the last base created gets the signals, in libev, the	3984	=item * In libevent, the last base created gets the signals, in libev, the
3243	first base created (== the default loop) gets the signals.	3985	base that registered the signal gets the signals.
3244		3986
3245	=item * Other members are not supported.	3987	=item * Other members are not supported.
3246		3988
3247	=item * The libev emulation is I<not> ABI compatible to libevent, you need	3989	=item * The libev emulation is I<not> ABI compatible to libevent, you need
3248	to use the libev header file and library.	3990	to use the libev header file and library.
3249		3991
3250	=back	3992	=back
3251		3993
3252	=head1 C++ SUPPORT	3994	=head1 C++ SUPPORT
		3995
		3996	=head2 C API
		3997
		3998	The normal C API should work fine when used from C++: both ev.h and the
		3999	libev sources can be compiled as C++. Therefore, code that uses the C API
		4000	will work fine.
		4001
		4002	Proper exception specifications might have to be added to callbacks passed
		4003	to libev: exceptions may be thrown only from watcher callbacks, all other
		4004	callbacks (allocator, syserr, loop acquire/release and periodic reschedule
		4005	callbacks) must not throw exceptions, and might need a C<noexcept>
		4006	specification. If you have code that needs to be compiled as both C and
		4007	C++ you can use the C<EV_NOEXCEPT> macro for this:
		4008
		4009	static void
		4010	fatal_error (const char *msg) EV_NOEXCEPT
		4011	{
		4012	perror (msg);
		4013	abort ();
		4014	}
		4015
		4016	...
		4017	ev_set_syserr_cb (fatal_error);
		4018
		4019	The only API functions that can currently throw exceptions are C<ev_run>,
		4020	C<ev_invoke>, C<ev_invoke_pending> and C<ev_loop_destroy> (the latter
		4021	because it runs cleanup watchers).
		4022
		4023	Throwing exceptions in watcher callbacks is only supported if libev itself
		4024	is compiled with a C++ compiler or your C and C++ environments allow
		4025	throwing exceptions through C libraries (most do).
		4026
		4027	=head2 C++ API
3253		4028
3254	Libev comes with some simplistic wrapper classes for C++ that mainly allow	4029	Libev comes with some simplistic wrapper classes for C++ that mainly allow
3255	you to use some convenience methods to start/stop watchers and also change	4030	you to use some convenience methods to start/stop watchers and also change
3256	the callback model to a model using method callbacks on objects.	4031	the callback model to a model using method callbacks on objects.
3257		4032
3258	To use it,	4033	To use it,
3259		4034
3260	#include <ev++.h>	4035	#include <ev++.h>
3261		4036
3262	This automatically includes F<ev.h> and puts all of its definitions (many	4037	This automatically includes F<ev.h> and puts all of its definitions (many
3263	of them macros) into the global namespace. All C++ specific things are	4038	of them macros) into the global namespace. All C++ specific things are
3264	put into the C<ev> namespace. It should support all the same embedding	4039	put into the C<ev> namespace. It should support all the same embedding
…		…
3267	Care has been taken to keep the overhead low. The only data member the C++	4042	Care has been taken to keep the overhead low. The only data member the C++
3268	classes add (compared to plain C-style watchers) is the event loop pointer	4043	classes add (compared to plain C-style watchers) is the event loop pointer
3269	that the watcher is associated with (or no additional members at all if	4044	that the watcher is associated with (or no additional members at all if
3270	you disable C<EV_MULTIPLICITY> when embedding libev).	4045	you disable C<EV_MULTIPLICITY> when embedding libev).
3271		4046
3272	Currently, functions, and static and non-static member functions can be	4047	Currently, functions, static and non-static member functions and classes
3273	used as callbacks. Other types should be easy to add as long as they only	4048	with C<operator ()> can be used as callbacks. Other types should be easy
3274	need one additional pointer for context. If you need support for other	4049	to add as long as they only need one additional pointer for context. If
3275	types of functors please contact the author (preferably after implementing	4050	you need support for other types of functors please contact the author
3276	it).	4051	(preferably after implementing it).
		4052
		4053	For all this to work, your C++ compiler either has to use the same calling
		4054	conventions as your C compiler (for static member functions), or you have
		4055	to embed libev and compile libev itself as C++.
3277		4056
3278	Here is a list of things available in the C<ev> namespace:	4057	Here is a list of things available in the C<ev> namespace:
3279		4058
3280	=over 4	4059	=over 4
3281		4060
…		…
3291	=item C<ev::io>, C<ev::timer>, C<ev::periodic>, C<ev::idle>, C<ev::sig> etc.	4070	=item C<ev::io>, C<ev::timer>, C<ev::periodic>, C<ev::idle>, C<ev::sig> etc.
3292		4071
3293	For each C<ev_TYPE> watcher in F<ev.h> there is a corresponding class of	4072	For each C<ev_TYPE> watcher in F<ev.h> there is a corresponding class of
3294	the same name in the C<ev> namespace, with the exception of C<ev_signal>	4073	the same name in the C<ev> namespace, with the exception of C<ev_signal>
3295	which is called C<ev::sig> to avoid clashes with the C<signal> macro	4074	which is called C<ev::sig> to avoid clashes with the C<signal> macro
3296	defines by many implementations.	4075	defined by many implementations.
3297		4076
3298	All of those classes have these methods:	4077	All of those classes have these methods:
3299		4078
3300	=over 4	4079	=over 4
3301		4080
…		…
3363	void operator() (ev::io &w, int revents)	4142	void operator() (ev::io &w, int revents)
3364	{	4143	{
3365	...	4144	...
3366	}	4145	}
3367	}	4146	}
3368		4147
3369	myfunctor f;	4148	myfunctor f;
3370		4149
3371	ev::io w;	4150	ev::io w;
3372	w.set (&f);	4151	w.set (&f);
3373		4152
…		…
3391	Associates a different C<struct ev_loop> with this watcher. You can only	4170	Associates a different C<struct ev_loop> with this watcher. You can only
3392	do this when the watcher is inactive (and not pending either).	4171	do this when the watcher is inactive (and not pending either).
3393		4172
3394	=item w->set ([arguments])	4173	=item w->set ([arguments])
3395		4174
3396	Basically the same as C<ev_TYPE_set>, with the same arguments. Must be	4175	Basically the same as C<ev_TYPE_set> (except for C<ev::embed> watchers>),
		4176	with the same arguments. Either this method or a suitable start method
3397	called at least once. Unlike the C counterpart, an active watcher gets	4177	must be called at least once. Unlike the C counterpart, an active watcher
3398	automatically stopped and restarted when reconfiguring it with this	4178	gets automatically stopped and restarted when reconfiguring it with this
3399	method.	4179	method.
		4180
		4181	For C<ev::embed> watchers this method is called C<set_embed>, to avoid
		4182	clashing with the C<set (loop)> method.
3400		4183
3401	=item w->start ()	4184	=item w->start ()
3402		4185
3403	Starts the watcher. Note that there is no C<loop> argument, as the	4186	Starts the watcher. Note that there is no C<loop> argument, as the
3404	constructor already stores the event loop.	4187	constructor already stores the event loop.
3405		4188
		4189	=item w->start ([arguments])
		4190
		4191	Instead of calling C<set> and C<start> methods separately, it is often
		4192	convenient to wrap them in one call. Uses the same type of arguments as
		4193	the configure C<set> method of the watcher.
		4194
3406	=item w->stop ()	4195	=item w->stop ()
3407		4196
3408	Stops the watcher if it is active. Again, no C<loop> argument.	4197	Stops the watcher if it is active. Again, no C<loop> argument.
3409		4198
3410	=item w->again () (C<ev::timer>, C<ev::periodic> only)	4199	=item w->again () (C<ev::timer>, C<ev::periodic> only)
…		…
3422		4211
3423	=back	4212	=back
3424		4213
3425	=back	4214	=back
3426		4215
3427	Example: Define a class with an IO and idle watcher, start one of them in	4216	Example: Define a class with two I/O and idle watchers, start the I/O
3428	the constructor.	4217	watchers in the constructor.
3429		4218
3430	class myclass	4219	class myclass
3431	{	4220	{
3432	ev::io io ; void io_cb (ev::io &w, int revents);	4221	ev::io io ; void io_cb (ev::io &w, int revents);
		4222	ev::io io2 ; void io2_cb (ev::io &w, int revents);
3433	ev::idle idle; void idle_cb (ev::idle &w, int revents);	4223	ev::idle idle; void idle_cb (ev::idle &w, int revents);
3434		4224
3435	myclass (int fd)	4225	myclass (int fd)
3436	{	4226	{
3437	io .set <myclass, &myclass::io_cb > (this);	4227	io .set <myclass, &myclass::io_cb > (this);
		4228	io2 .set <myclass, &myclass::io2_cb > (this);
3438	idle.set <myclass, &myclass::idle_cb> (this);	4229	idle.set <myclass, &myclass::idle_cb> (this);
3439		4230
3440	io.start (fd, ev::READ);	4231	io.set (fd, ev::WRITE); // configure the watcher
		4232	io.start (); // start it whenever convenient
		4233
		4234	io2.start (fd, ev::READ); // set + start in one call
3441	}	4235	}
3442	};	4236	};
3443		4237
3444		4238
3445	=head1 OTHER LANGUAGE BINDINGS	4239	=head1 OTHER LANGUAGE BINDINGS
…		…
3484	L<http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hlibev>.	4278	L<http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hlibev>.
3485		4279
3486	=item D	4280	=item D
3487		4281
3488	Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to	4282	Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to
3489	be found at L<http://proj.llucax.com.ar/wiki/evd>.	4283	be found at L<http://www.llucax.com.ar/proj/ev.d/index.html>.
3490		4284
3491	=item Ocaml	4285	=item Ocaml
3492		4286
3493	Erkki Seppala has written Ocaml bindings for libev, to be found at	4287	Erkki Seppala has written Ocaml bindings for libev, to be found at
3494	L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>.	4288	L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>.
…		…
3497		4291
3498	Brian Maher has written a partial interface to libev for lua (at the	4292	Brian Maher has written a partial interface to libev for lua (at the
3499	time of this writing, only C<ev_io> and C<ev_timer>), to be found at	4293	time of this writing, only C<ev_io> and C<ev_timer>), to be found at
3500	L<http://github.com/brimworks/lua-ev>.	4294	L<http://github.com/brimworks/lua-ev>.
3501		4295
		4296	=item Javascript
		4297
		4298	Node.js (L<http://nodejs.org>) uses libev as the underlying event library.
		4299
		4300	=item Others
		4301
		4302	There are others, and I stopped counting.
		4303
3502	=back	4304	=back
3503		4305
3504		4306
3505	=head1 MACRO MAGIC	4307	=head1 MACRO MAGIC
3506		4308
…		…
3519	loop argument"). The C<EV_A> form is used when this is the sole argument,	4321	loop argument"). The C<EV_A> form is used when this is the sole argument,
3520	C<EV_A_> is used when other arguments are following. Example:	4322	C<EV_A_> is used when other arguments are following. Example:
3521		4323
3522	ev_unref (EV_A);	4324	ev_unref (EV_A);
3523	ev_timer_add (EV_A_ watcher);	4325	ev_timer_add (EV_A_ watcher);
3524	ev_loop (EV_A_ 0);	4326	ev_run (EV_A_ 0);
3525		4327
3526	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	4328	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
3527	which is often provided by the following macro.	4329	which is often provided by the following macro.
3528		4330
3529	=item C<EV_P>, C<EV_P_>	4331	=item C<EV_P>, C<EV_P_>
…		…
3542	suitable for use with C<EV_A>.	4344	suitable for use with C<EV_A>.
3543		4345
3544	=item C<EV_DEFAULT>, C<EV_DEFAULT_>	4346	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
3545		4347
3546	Similar to the other two macros, this gives you the value of the default	4348	Similar to the other two macros, this gives you the value of the default
3547	loop, if multiple loops are supported ("ev loop default").	4349	loop, if multiple loops are supported ("ev loop default"). The default loop
		4350	will be initialised if it isn't already initialised.
		4351
		4352	For non-multiplicity builds, these macros do nothing, so you always have
		4353	to initialise the loop somewhere.
3548		4354
3549	=item C<EV_DEFAULT_UC>, C<EV_DEFAULT_UC_>	4355	=item C<EV_DEFAULT_UC>, C<EV_DEFAULT_UC_>
3550		4356
3551	Usage identical to C<EV_DEFAULT> and C<EV_DEFAULT_>, but requires that the	4357	Usage identical to C<EV_DEFAULT> and C<EV_DEFAULT_>, but requires that the
3552	default loop has been initialised (C<UC> == unchecked). Their behaviour	4358	default loop has been initialised (C<UC> == unchecked). Their behaviour
…		…
3569	}	4375	}
3570		4376
3571	ev_check check;	4377	ev_check check;
3572	ev_check_init (&check, check_cb);	4378	ev_check_init (&check, check_cb);
3573	ev_check_start (EV_DEFAULT_ &check);	4379	ev_check_start (EV_DEFAULT_ &check);
3574	ev_loop (EV_DEFAULT_ 0);	4380	ev_run (EV_DEFAULT_ 0);
3575		4381
3576	=head1 EMBEDDING	4382	=head1 EMBEDDING
3577		4383
3578	Libev can (and often is) directly embedded into host	4384	Libev can (and often is) directly embedded into host
3579	applications. Examples of applications that embed it include the Deliantra	4385	applications. Examples of applications that embed it include the Deliantra
…		…
3619	ev_vars.h	4425	ev_vars.h
3620	ev_wrap.h	4426	ev_wrap.h
3621		4427
3622	ev_win32.c required on win32 platforms only	4428	ev_win32.c required on win32 platforms only
3623		4429
3624	ev_select.c only when select backend is enabled (which is enabled by default)	4430	ev_select.c only when select backend is enabled
3625	ev_poll.c only when poll backend is enabled (disabled by default)	4431	ev_poll.c only when poll backend is enabled
3626	ev_epoll.c only when the epoll backend is enabled (disabled by default)	4432	ev_epoll.c only when the epoll backend is enabled
3627	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	4433	ev_kqueue.c only when the kqueue backend is enabled
3628	ev_port.c only when the solaris port backend is enabled (disabled by default)	4434	ev_port.c only when the solaris port backend is enabled
3629		4435
3630	F<ev.c> includes the backend files directly when enabled, so you only need	4436	F<ev.c> includes the backend files directly when enabled, so you only need
3631	to compile this single file.	4437	to compile this single file.
3632		4438
3633	=head3 LIBEVENT COMPATIBILITY API	4439	=head3 LIBEVENT COMPATIBILITY API
…		…
3671	users of libev and the libev code itself must be compiled with compatible	4477	users of libev and the libev code itself must be compiled with compatible
3672	settings.	4478	settings.
3673		4479
3674	=over 4	4480	=over 4
3675		4481
		4482	=item EV_COMPAT3 (h)
		4483
		4484	Backwards compatibility is a major concern for libev. This is why this
		4485	release of libev comes with wrappers for the functions and symbols that
		4486	have been renamed between libev version 3 and 4.
		4487
		4488	You can disable these wrappers (to test compatibility with future
		4489	versions) by defining C<EV_COMPAT3> to C<0> when compiling your
		4490	sources. This has the additional advantage that you can drop the C<struct>
		4491	from C<struct ev_loop> declarations, as libev will provide an C<ev_loop>
		4492	typedef in that case.
		4493
		4494	In some future version, the default for C<EV_COMPAT3> will become C<0>,
		4495	and in some even more future version the compatibility code will be
		4496	removed completely.
		4497
3676	=item EV_STANDALONE (h)	4498	=item EV_STANDALONE (h)
3677		4499
3678	Must always be C<1> if you do not use autoconf configuration, which	4500	Must always be C<1> if you do not use autoconf configuration, which
3679	keeps libev from including F<config.h>, and it also defines dummy	4501	keeps libev from including F<config.h>, and it also defines dummy
3680	implementations for some libevent functions (such as logging, which is not	4502	implementations for some libevent functions (such as logging, which is not
3681	supported). It will also not define any of the structs usually found in	4503	supported). It will also not define any of the structs usually found in
3682	F<event.h> that are not directly supported by the libev core alone.	4504	F<event.h> that are not directly supported by the libev core alone.
3683		4505
3684	In standalone mode, libev will still try to automatically deduce the	4506	In standalone mode, libev will still try to automatically deduce the
3685	configuration, but has to be more conservative.	4507	configuration, but has to be more conservative.
		4508
		4509	=item EV_USE_FLOOR
		4510
		4511	If defined to be C<1>, libev will use the C<floor ()> function for its
		4512	periodic reschedule calculations, otherwise libev will fall back on a
		4513	portable (slower) implementation. If you enable this, you usually have to
		4514	link against libm or something equivalent. Enabling this when the C<floor>
		4515	function is not available will fail, so the safe default is to not enable
		4516	this.
3686		4517
3687	=item EV_USE_MONOTONIC	4518	=item EV_USE_MONOTONIC
3688		4519
3689	If defined to be C<1>, libev will try to detect the availability of the	4520	If defined to be C<1>, libev will try to detect the availability of the
3690	monotonic clock option at both compile time and runtime. Otherwise no	4521	monotonic clock option at both compile time and runtime. Otherwise no
…		…
3775		4606
3776	If programs implement their own fd to handle mapping on win32, then this	4607	If programs implement their own fd to handle mapping on win32, then this
3777	macro can be used to override the C<close> function, useful to unregister	4608	macro can be used to override the C<close> function, useful to unregister
3778	file descriptors again. Note that the replacement function has to close	4609	file descriptors again. Note that the replacement function has to close
3779	the underlying OS handle.	4610	the underlying OS handle.
		4611
		4612	=item EV_USE_WSASOCKET
		4613
		4614	If defined to be C<1>, libev will use C<WSASocket> to create its internal
		4615	communication socket, which works better in some environments. Otherwise,
		4616	the normal C<socket> function will be used, which works better in other
		4617	environments.
3780		4618
3781	=item EV_USE_POLL	4619	=item EV_USE_POLL
3782		4620
3783	If defined to be C<1>, libev will compile in support for the C<poll>(2)	4621	If defined to be C<1>, libev will compile in support for the C<poll>(2)
3784	backend. Otherwise it will be enabled on non-win32 platforms. It	4622	backend. Otherwise it will be enabled on non-win32 platforms. It
…		…
3820	If defined to be C<1>, libev will compile in support for the Linux inotify	4658	If defined to be C<1>, libev will compile in support for the Linux inotify
3821	interface to speed up C<ev_stat> watchers. Its actual availability will	4659	interface to speed up C<ev_stat> watchers. Its actual availability will
3822	be detected at runtime. If undefined, it will be enabled if the headers	4660	be detected at runtime. If undefined, it will be enabled if the headers
3823	indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled.	4661	indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled.
3824		4662
		4663	=item EV_NO_SMP
		4664
		4665	If defined to be C<1>, libev will assume that memory is always coherent
		4666	between threads, that is, threads can be used, but threads never run on
		4667	different cpus (or different cpu cores). This reduces dependencies
		4668	and makes libev faster.
		4669
		4670	=item EV_NO_THREADS
		4671
		4672	If defined to be C<1>, libev will assume that it will never be called from
		4673	different threads (that includes signal handlers), which is a stronger
		4674	assumption than C<EV_NO_SMP>, above. This reduces dependencies and makes
		4675	libev faster.
		4676
3825	=item EV_ATOMIC_T	4677	=item EV_ATOMIC_T
3826		4678
3827	Libev requires an integer type (suitable for storing C<0> or C<1>) whose	4679	Libev requires an integer type (suitable for storing C<0> or C<1>) whose
3828	access is atomic with respect to other threads or signal contexts. No such	4680	access is atomic with respect to other threads or signal contexts. No
3829	type is easily found in the C language, so you can provide your own type	4681	such type is easily found in the C language, so you can provide your own
3830	that you know is safe for your purposes. It is used both for signal handler "locking"	4682	type that you know is safe for your purposes. It is used both for signal
3831	as well as for signal and thread safety in C<ev_async> watchers.	4683	handler "locking" as well as for signal and thread safety in C<ev_async>
		4684	watchers.
3832		4685
3833	In the absence of this define, libev will use C<sig_atomic_t volatile>	4686	In the absence of this define, libev will use C<sig_atomic_t volatile>
3834	(from F<signal.h>), which is usually good enough on most platforms.	4687	(from F<signal.h>), which is usually good enough on most platforms.
3835		4688
3836	=item EV_H (h)	4689	=item EV_H (h)
…		…
3863	will have the C<struct ev_loop *> as first argument, and you can create	4716	will have the C<struct ev_loop *> as first argument, and you can create
3864	additional independent event loops. Otherwise there will be no support	4717	additional independent event loops. Otherwise there will be no support
3865	for multiple event loops and there is no first event loop pointer	4718	for multiple event loops and there is no first event loop pointer
3866	argument. Instead, all functions act on the single default loop.	4719	argument. Instead, all functions act on the single default loop.
3867		4720
		4721	Note that C<EV_DEFAULT> and C<EV_DEFAULT_> will no longer provide a
		4722	default loop when multiplicity is switched off - you always have to
		4723	initialise the loop manually in this case.
		4724
3868	=item EV_MINPRI	4725	=item EV_MINPRI
3869		4726
3870	=item EV_MAXPRI	4727	=item EV_MAXPRI
3871		4728
3872	The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to	4729	The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to
…		…
3908	#define EV_USE_POLL 1	4765	#define EV_USE_POLL 1
3909	#define EV_CHILD_ENABLE 1	4766	#define EV_CHILD_ENABLE 1
3910	#define EV_ASYNC_ENABLE 1	4767	#define EV_ASYNC_ENABLE 1
3911		4768
3912	The actual value is a bitset, it can be a combination of the following	4769	The actual value is a bitset, it can be a combination of the following
3913	values:	4770	values (by default, all of these are enabled):
3914		4771
3915	=over 4	4772	=over 4
3916		4773
3917	=item C<1> - faster/larger code	4774	=item C<1> - faster/larger code
3918		4775
…		…
3922	code size by roughly 30% on amd64).	4779	code size by roughly 30% on amd64).
3923		4780
3924	When optimising for size, use of compiler flags such as C<-Os> with	4781	When optimising for size, use of compiler flags such as C<-Os> with
3925	gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of	4782	gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of
3926	assertions.	4783	assertions.
		4784
		4785	The default is off when C<__OPTIMIZE_SIZE__> is defined by your compiler
		4786	(e.g. gcc with C<-Os>).
3927		4787
3928	=item C<2> - faster/larger data structures	4788	=item C<2> - faster/larger data structures
3929		4789
3930	Replaces the small 2-heap for timer management by a faster 4-heap, larger	4790	Replaces the small 2-heap for timer management by a faster 4-heap, larger
3931	hash table sizes and so on. This will usually further increase code size	4791	hash table sizes and so on. This will usually further increase code size
3932	and can additionally have an effect on the size of data structures at	4792	and can additionally have an effect on the size of data structures at
3933	runtime.	4793	runtime.
3934		4794
		4795	The default is off when C<__OPTIMIZE_SIZE__> is defined by your compiler
		4796	(e.g. gcc with C<-Os>).
		4797
3935	=item C<4> - full API configuration	4798	=item C<4> - full API configuration
3936		4799
3937	This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and	4800	This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and
3938	enables multiplicity (C<EV_MULTIPLICITY>=1).	4801	enables multiplicity (C<EV_MULTIPLICITY>=1).
3939		4802
…		…
3969		4832
3970	With an intelligent-enough linker (gcc+binutils are intelligent enough	4833	With an intelligent-enough linker (gcc+binutils are intelligent enough
3971	when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by	4834	when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by
3972	your program might be left out as well - a binary starting a timer and an	4835	your program might be left out as well - a binary starting a timer and an
3973	I/O watcher then might come out at only 5Kb.	4836	I/O watcher then might come out at only 5Kb.
		4837
		4838	=item EV_API_STATIC
		4839
		4840	If this symbol is defined (by default it is not), then all identifiers
		4841	will have static linkage. This means that libev will not export any
		4842	identifiers, and you cannot link against libev anymore. This can be useful
		4843	when you embed libev, only want to use libev functions in a single file,
		4844	and do not want its identifiers to be visible.
		4845
		4846	To use this, define C<EV_API_STATIC> and include F<ev.c> in the file that
		4847	wants to use libev.
		4848
		4849	This option only works when libev is compiled with a C compiler, as C++
		4850	doesn't support the required declaration syntax.
3974		4851
3975	=item EV_AVOID_STDIO	4852	=item EV_AVOID_STDIO
3976		4853
3977	If this is set to C<1> at compiletime, then libev will avoid using stdio	4854	If this is set to C<1> at compiletime, then libev will avoid using stdio
3978	functions (printf, scanf, perror etc.). This will increase the code size	4855	functions (printf, scanf, perror etc.). This will increase the code size
…		…
4029	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it	4906	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
4030	will be C<0>.	4907	will be C<0>.
4031		4908
4032	=item EV_VERIFY	4909	=item EV_VERIFY
4033		4910
4034	Controls how much internal verification (see C<ev_loop_verify ()>) will	4911	Controls how much internal verification (see C<ev_verify ()>) will
4035	be done: If set to C<0>, no internal verification code will be compiled	4912	be done: If set to C<0>, no internal verification code will be compiled
4036	in. If set to C<1>, then verification code will be compiled in, but not	4913	in. If set to C<1>, then verification code will be compiled in, but not
4037	called. If set to C<2>, then the internal verification code will be	4914	called. If set to C<2>, then the internal verification code will be
4038	called once per loop, which can slow down libev. If set to C<3>, then the	4915	called once per loop, which can slow down libev. If set to C<3>, then the
4039	verification code will be called very frequently, which will slow down	4916	verification code will be called very frequently, which will slow down
…		…
4122	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	4999	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
4123		5000
4124	#include "ev_cpp.h"	5001	#include "ev_cpp.h"
4125	#include "ev.c"	5002	#include "ev.c"
4126		5003
4127	=head1 INTERACTION WITH OTHER PROGRAMS OR LIBRARIES	5004	=head1 INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT
4128		5005
4129	=head2 THREADS AND COROUTINES	5006	=head2 THREADS AND COROUTINES
4130		5007
4131	=head3 THREADS	5008	=head3 THREADS
4132		5009
…		…
4183	default loop and triggering an C<ev_async> watcher from the default loop	5060	default loop and triggering an C<ev_async> watcher from the default loop
4184	watcher callback into the event loop interested in the signal.	5061	watcher callback into the event loop interested in the signal.
4185		5062
4186	=back	5063	=back
4187		5064
4188	=head4 THREAD LOCKING EXAMPLE	5065	See also L</THREAD LOCKING EXAMPLE>.
4189
4190	Here is a fictitious example of how to run an event loop in a different
4191	thread than where callbacks are being invoked and watchers are
4192	created/added/removed.
4193
4194	For a real-world example, see the C<EV::Loop::Async> perl module,
4195	which uses exactly this technique (which is suited for many high-level
4196	languages).
4197
4198	The example uses a pthread mutex to protect the loop data, a condition
4199	variable to wait for callback invocations, an async watcher to notify the
4200	event loop thread and an unspecified mechanism to wake up the main thread.
4201
4202	First, you need to associate some data with the event loop:
4203
4204	typedef struct {
4205	mutex_t lock; /* global loop lock */
4206	ev_async async_w;
4207	thread_t tid;
4208	cond_t invoke_cv;
4209	} userdata;
4210
4211	void prepare_loop (EV_P)
4212	{
4213	// for simplicity, we use a static userdata struct.
4214	static userdata u;
4215
4216	ev_async_init (&u->async_w, async_cb);
4217	ev_async_start (EV_A_ &u->async_w);
4218
4219	pthread_mutex_init (&u->lock, 0);
4220	pthread_cond_init (&u->invoke_cv, 0);
4221
4222	// now associate this with the loop
4223	ev_set_userdata (EV_A_ u);
4224	ev_set_invoke_pending_cb (EV_A_ l_invoke);
4225	ev_set_loop_release_cb (EV_A_ l_release, l_acquire);
4226
4227	// then create the thread running ev_loop
4228	pthread_create (&u->tid, 0, l_run, EV_A);
4229	}
4230
4231	The callback for the C<ev_async> watcher does nothing: the watcher is used
4232	solely to wake up the event loop so it takes notice of any new watchers
4233	that might have been added:
4234
4235	static void
4236	async_cb (EV_P_ ev_async *w, int revents)
4237	{
4238	// just used for the side effects
4239	}
4240
4241	The C<l_release> and C<l_acquire> callbacks simply unlock/lock the mutex
4242	protecting the loop data, respectively.
4243
4244	static void
4245	l_release (EV_P)
4246	{
4247	userdata *u = ev_userdata (EV_A);
4248	pthread_mutex_unlock (&u->lock);
4249	}
4250
4251	static void
4252	l_acquire (EV_P)
4253	{
4254	userdata *u = ev_userdata (EV_A);
4255	pthread_mutex_lock (&u->lock);
4256	}
4257
4258	The event loop thread first acquires the mutex, and then jumps straight
4259	into C<ev_loop>:
4260
4261	void *
4262	l_run (void *thr_arg)
4263	{
4264	struct ev_loop *loop = (struct ev_loop *)thr_arg;
4265
4266	l_acquire (EV_A);
4267	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
4268	ev_loop (EV_A_ 0);
4269	l_release (EV_A);
4270
4271	return 0;
4272	}
4273
4274	Instead of invoking all pending watchers, the C<l_invoke> callback will
4275	signal the main thread via some unspecified mechanism (signals? pipe
4276	writes? C<Async::Interrupt>?) and then waits until all pending watchers
4277	have been called (in a while loop because a) spurious wakeups are possible
4278	and b) skipping inter-thread-communication when there are no pending
4279	watchers is very beneficial):
4280
4281	static void
4282	l_invoke (EV_P)
4283	{
4284	userdata *u = ev_userdata (EV_A);
4285
4286	while (ev_pending_count (EV_A))
4287	{
4288	wake_up_other_thread_in_some_magic_or_not_so_magic_way ();
4289	pthread_cond_wait (&u->invoke_cv, &u->lock);
4290	}
4291	}
4292
4293	Now, whenever the main thread gets told to invoke pending watchers, it
4294	will grab the lock, call C<ev_invoke_pending> and then signal the loop
4295	thread to continue:
4296
4297	static void
4298	real_invoke_pending (EV_P)
4299	{
4300	userdata *u = ev_userdata (EV_A);
4301
4302	pthread_mutex_lock (&u->lock);
4303	ev_invoke_pending (EV_A);
4304	pthread_cond_signal (&u->invoke_cv);
4305	pthread_mutex_unlock (&u->lock);
4306	}
4307
4308	Whenever you want to start/stop a watcher or do other modifications to an
4309	event loop, you will now have to lock:
4310
4311	ev_timer timeout_watcher;
4312	userdata *u = ev_userdata (EV_A);
4313
4314	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
4315
4316	pthread_mutex_lock (&u->lock);
4317	ev_timer_start (EV_A_ &timeout_watcher);
4318	ev_async_send (EV_A_ &u->async_w);
4319	pthread_mutex_unlock (&u->lock);
4320
4321	Note that sending the C<ev_async> watcher is required because otherwise
4322	an event loop currently blocking in the kernel will have no knowledge
4323	about the newly added timer. By waking up the loop it will pick up any new
4324	watchers in the next event loop iteration.
4325		5066
4326	=head3 COROUTINES	5067	=head3 COROUTINES
4327		5068
4328	Libev is very accommodating to coroutines ("cooperative threads"):	5069	Libev is very accommodating to coroutines ("cooperative threads"):
4329	libev fully supports nesting calls to its functions from different	5070	libev fully supports nesting calls to its functions from different
4330	coroutines (e.g. you can call C<ev_loop> on the same loop from two	5071	coroutines (e.g. you can call C<ev_run> on the same loop from two
4331	different coroutines, and switch freely between both coroutines running	5072	different coroutines, and switch freely between both coroutines running
4332	the loop, as long as you don't confuse yourself). The only exception is	5073	the loop, as long as you don't confuse yourself). The only exception is
4333	that you must not do this from C<ev_periodic> reschedule callbacks.	5074	that you must not do this from C<ev_periodic> reschedule callbacks.
4334		5075
4335	Care has been taken to ensure that libev does not keep local state inside	5076	Care has been taken to ensure that libev does not keep local state inside
4336	C<ev_loop>, and other calls do not usually allow for coroutine switches as	5077	C<ev_run>, and other calls do not usually allow for coroutine switches as
4337	they do not call any callbacks.	5078	they do not call any callbacks.
4338		5079
4339	=head2 COMPILER WARNINGS	5080	=head2 COMPILER WARNINGS
4340		5081
4341	Depending on your compiler and compiler settings, you might get no or a	5082	Depending on your compiler and compiler settings, you might get no or a
…		…
4425	=head3 C<kqueue> is buggy	5166	=head3 C<kqueue> is buggy
4426		5167
4427	The kqueue syscall is broken in all known versions - most versions support	5168	The kqueue syscall is broken in all known versions - most versions support
4428	only sockets, many support pipes.	5169	only sockets, many support pipes.
4429		5170
4430	Libev tries to work around this by not using C<kqueue> by default on	5171	Libev tries to work around this by not using C<kqueue> by default on this
4431	this rotten platform, but of course you can still ask for it when creating	5172	rotten platform, but of course you can still ask for it when creating a
4432	a loop.	5173	loop - embedding a socket-only kqueue loop into a select-based one is
		5174	probably going to work well.
4433		5175
4434	=head3 C<poll> is buggy	5176	=head3 C<poll> is buggy
4435		5177
4436	Instead of fixing C<kqueue>, Apple replaced their (working) C<poll>	5178	Instead of fixing C<kqueue>, Apple replaced their (working) C<poll>
4437	implementation by something calling C<kqueue> internally around the 10.5.6	5179	implementation by something calling C<kqueue> internally around the 10.5.6
…		…
4456		5198
4457	=head3 C<errno> reentrancy	5199	=head3 C<errno> reentrancy
4458		5200
4459	The default compile environment on Solaris is unfortunately so	5201	The default compile environment on Solaris is unfortunately so
4460	thread-unsafe that you can't even use components/libraries compiled	5202	thread-unsafe that you can't even use components/libraries compiled
4461	without C<-D_REENTRANT> (as long as they use C<errno>), which, of course,	5203	without C<-D_REENTRANT> in a threaded program, which, of course, isn't
4462	isn't defined by default.	5204	defined by default. A valid, if stupid, implementation choice.
4463		5205
4464	If you want to use libev in threaded environments you have to make sure	5206	If you want to use libev in threaded environments you have to make sure
4465	it's compiled with C<_REENTRANT> defined.	5207	it's compiled with C<_REENTRANT> defined.
4466		5208
4467	=head3 Event port backend	5209	=head3 Event port backend
4468		5210
4469	The scalable event interface for Solaris is called "event ports". Unfortunately,	5211	The scalable event interface for Solaris is called "event
4470	this mechanism is very buggy. If you run into high CPU usage, your program	5212	ports". Unfortunately, this mechanism is very buggy in all major
		5213	releases. If you run into high CPU usage, your program freezes or you get
4471	freezes or you get a large number of spurious wakeups, make sure you have	5214	a large number of spurious wakeups, make sure you have all the relevant
4472	all the relevant and latest kernel patches applied. No, I don't know which	5215	and latest kernel patches applied. No, I don't know which ones, but there
4473	ones, but there are multiple ones.	5216	are multiple ones to apply, and afterwards, event ports actually work
		5217	great.
4474		5218
4475	If you can't get it to work, you can try running the program by setting	5219	If you can't get it to work, you can try running the program by setting
4476	the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and	5220	the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and
4477	C<select> backends.	5221	C<select> backends.
4478		5222
4479	=head2 AIX POLL BUG	5223	=head2 AIX POLL BUG
4480		5224
4481	AIX unfortunately has a broken C<poll.h> header. Libev works around	5225	AIX unfortunately has a broken C<poll.h> header. Libev works around
4482	this by trying to avoid the poll backend altogether (i.e. it's not even	5226	this by trying to avoid the poll backend altogether (i.e. it's not even
4483	compiled in), which normally isn't a big problem as C<select> works fine	5227	compiled in), which normally isn't a big problem as C<select> works fine
4484	with large bitsets, and AIX is dead anyway.	5228	with large bitsets on AIX, and AIX is dead anyway.
4485		5229
4486	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS	5230	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
4487		5231
4488	=head3 General issues	5232	=head3 General issues
4489		5233
…		…
4491	requires, and its I/O model is fundamentally incompatible with the POSIX	5235	requires, and its I/O model is fundamentally incompatible with the POSIX
4492	model. Libev still offers limited functionality on this platform in	5236	model. Libev still offers limited functionality on this platform in
4493	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	5237	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
4494	descriptors. This only applies when using Win32 natively, not when using	5238	descriptors. This only applies when using Win32 natively, not when using
4495	e.g. cygwin. Actually, it only applies to the microsofts own compilers,	5239	e.g. cygwin. Actually, it only applies to the microsofts own compilers,
4496	as every compielr comes with a slightly differently broken/incompatible	5240	as every compiler comes with a slightly differently broken/incompatible
4497	environment.	5241	environment.
4498		5242
4499	Lifting these limitations would basically require the full	5243	Lifting these limitations would basically require the full
4500	re-implementation of the I/O system. If you are into this kind of thing,	5244	re-implementation of the I/O system. If you are into this kind of thing,
4501	then note that glib does exactly that for you in a very portable way (note	5245	then note that glib does exactly that for you in a very portable way (note
…		…
4595	structure (guaranteed by POSIX but not by ISO C for example), but it also	5339	structure (guaranteed by POSIX but not by ISO C for example), but it also
4596	assumes that the same (machine) code can be used to call any watcher	5340	assumes that the same (machine) code can be used to call any watcher
4597	callback: The watcher callbacks have different type signatures, but libev	5341	callback: The watcher callbacks have different type signatures, but libev
4598	calls them using an C<ev_watcher *> internally.	5342	calls them using an C<ev_watcher *> internally.
4599		5343
		5344	=item null pointers and integer zero are represented by 0 bytes
		5345
		5346	Libev uses C<memset> to initialise structs and arrays to C<0> bytes, and
		5347	relies on this setting pointers and integers to null.
		5348
		5349	=item pointer accesses must be thread-atomic
		5350
		5351	Accessing a pointer value must be atomic, it must both be readable and
		5352	writable in one piece - this is the case on all current architectures.
		5353
4600	=item C<sig_atomic_t volatile> must be thread-atomic as well	5354	=item C<sig_atomic_t volatile> must be thread-atomic as well
4601		5355
4602	The type C<sig_atomic_t volatile> (or whatever is defined as	5356	The type C<sig_atomic_t volatile> (or whatever is defined as
4603	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different	5357	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different
4604	threads. This is not part of the specification for C<sig_atomic_t>, but is	5358	threads. This is not part of the specification for C<sig_atomic_t>, but is
…		…
4612	thread" or will block signals process-wide, both behaviours would	5366	thread" or will block signals process-wide, both behaviours would
4613	be compatible with libev. Interaction between C<sigprocmask> and	5367	be compatible with libev. Interaction between C<sigprocmask> and
4614	C<pthread_sigmask> could complicate things, however.	5368	C<pthread_sigmask> could complicate things, however.
4615		5369
4616	The most portable way to handle signals is to block signals in all threads	5370	The most portable way to handle signals is to block signals in all threads
4617	except the initial one, and run the default loop in the initial thread as	5371	except the initial one, and run the signal handling loop in the initial
4618	well.	5372	thread as well.
4619		5373
4620	=item C<long> must be large enough for common memory allocation sizes	5374	=item C<long> must be large enough for common memory allocation sizes
4621		5375
4622	To improve portability and simplify its API, libev uses C<long> internally	5376	To improve portability and simplify its API, libev uses C<long> internally
4623	instead of C<size_t> when allocating its data structures. On non-POSIX	5377	instead of C<size_t> when allocating its data structures. On non-POSIX
…		…
4626	watchers.	5380	watchers.
4627		5381
4628	=item C<double> must hold a time value in seconds with enough accuracy	5382	=item C<double> must hold a time value in seconds with enough accuracy
4629		5383
4630	The type C<double> is used to represent timestamps. It is required to	5384	The type C<double> is used to represent timestamps. It is required to
4631	have at least 51 bits of mantissa (and 9 bits of exponent), which is good	5385	have at least 51 bits of mantissa (and 9 bits of exponent), which is
4632	enough for at least into the year 4000. This requirement is fulfilled by	5386	good enough for at least into the year 4000 with millisecond accuracy
		5387	(the design goal for libev). This requirement is overfulfilled by
4633	implementations implementing IEEE 754, which is basically all existing	5388	implementations using IEEE 754, which is basically all existing ones.
		5389
4634	ones. With IEEE 754 doubles, you get microsecond accuracy until at least	5390	With IEEE 754 doubles, you get microsecond accuracy until at least the
4635	2200.	5391	year 2255 (and millisecond accuracy till the year 287396 - by then, libev
		5392	is either obsolete or somebody patched it to use C<long double> or
		5393	something like that, just kidding).
4636		5394
4637	=back	5395	=back
4638		5396
4639	If you know of other additional requirements drop me a note.	5397	If you know of other additional requirements drop me a note.
4640		5398
…		…
4702	=item Processing ev_async_send: O(number_of_async_watchers)	5460	=item Processing ev_async_send: O(number_of_async_watchers)
4703		5461
4704	=item Processing signals: O(max_signal_number)	5462	=item Processing signals: O(max_signal_number)
4705		5463
4706	Sending involves a system call I<iff> there were no other C<ev_async_send>	5464	Sending involves a system call I<iff> there were no other C<ev_async_send>
4707	calls in the current loop iteration. Checking for async and signal events	5465	calls in the current loop iteration and the loop is currently
		5466	blocked. Checking for async and signal events involves iterating over all
4708	involves iterating over all running async watchers or all signal numbers.	5467	running async watchers or all signal numbers.
4709		5468
4710	=back	5469	=back
4711		5470
4712		5471
4713	=head1 PORTING FROM LIBEV 3.X TO 4.X	5472	=head1 PORTING FROM LIBEV 3.X TO 4.X
4714		5473
4715	The major version 4 introduced some minor incompatible changes to the API.	5474	The major version 4 introduced some incompatible changes to the API.
4716		5475
4717	At the moment, the C<ev.h> header file tries to implement superficial	5476	At the moment, the C<ev.h> header file provides compatibility definitions
4718	compatibility, so most programs should still compile. Those might be	5477	for all changes, so most programs should still compile. The compatibility
4719	removed in later versions of libev, so better update early than late.	5478	layer might be removed in later versions of libev, so better update to the
		5479	new API early than late.
4720		5480
4721	=over 4	5481	=over 4
4722		5482
4723	=item C<ev_loop_count> renamed to C<ev_iteration>	5483	=item C<EV_COMPAT3> backwards compatibility mechanism
4724		5484
4725	=item C<ev_loop_depth> renamed to C<ev_depth>	5485	The backward compatibility mechanism can be controlled by
		5486	C<EV_COMPAT3>. See L</"PREPROCESSOR SYMBOLS/MACROS"> in the L</EMBEDDING>
		5487	section.
4726		5488
4727	=item C<ev_loop_verify> renamed to C<ev_verify>	5489	=item C<ev_default_destroy> and C<ev_default_fork> have been removed
		5490
		5491	These calls can be replaced easily by their C<ev_loop_xxx> counterparts:
		5492
		5493	ev_loop_destroy (EV_DEFAULT_UC);
		5494	ev_loop_fork (EV_DEFAULT);
		5495
		5496	=item function/symbol renames
		5497
		5498	A number of functions and symbols have been renamed:
		5499
		5500	ev_loop => ev_run
		5501	EVLOOP_NONBLOCK => EVRUN_NOWAIT
		5502	EVLOOP_ONESHOT => EVRUN_ONCE
		5503
		5504	ev_unloop => ev_break
		5505	EVUNLOOP_CANCEL => EVBREAK_CANCEL
		5506	EVUNLOOP_ONE => EVBREAK_ONE
		5507	EVUNLOOP_ALL => EVBREAK_ALL
		5508
		5509	EV_TIMEOUT => EV_TIMER
		5510
		5511	ev_loop_count => ev_iteration
		5512	ev_loop_depth => ev_depth
		5513	ev_loop_verify => ev_verify
4728		5514
4729	Most functions working on C<struct ev_loop> objects don't have an	5515	Most functions working on C<struct ev_loop> objects don't have an
4730	C<ev_loop_> prefix, so it was removed. Note that C<ev_loop_fork> is	5516	C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and
		5517	associated constants have been renamed to not collide with the C<struct
		5518	ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme
		5519	as all other watcher types. Note that C<ev_loop_fork> is still called
4731	still called C<ev_loop_fork> because it would otherwise clash with the	5520	C<ev_loop_fork> because it would otherwise clash with the C<ev_fork>
4732	C<ev_fork> typedef.	5521	typedef.
4733
4734	=item C<EV_TIMEOUT> renamed to C<EV_TIMER> in C<revents>
4735
4736	This is a simple rename - all other watcher types use their name
4737	as revents flag, and now C<ev_timer> does, too.
4738
4739	Both C<EV_TIMER> and C<EV_TIMEOUT> symbols were present in 3.x versions
4740	and continue to be present for the foreseeable future, so this is mostly a
4741	documentation change.
4742		5522
4743	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>	5523	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>
4744		5524
4745	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different	5525	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different
4746	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile	5526	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile
…		…
4753		5533
4754	=over 4	5534	=over 4
4755		5535
4756	=item active	5536	=item active
4757		5537
4758	A watcher is active as long as it has been started (has been attached to	5538	A watcher is active as long as it has been started and not yet stopped.
4759	an event loop) but not yet stopped (disassociated from the event loop).	5539	See L</WATCHER STATES> for details.
4760		5540
4761	=item application	5541	=item application
4762		5542
4763	In this document, an application is whatever is using libev.	5543	In this document, an application is whatever is using libev.
		5544
		5545	=item backend
		5546
		5547	The part of the code dealing with the operating system interfaces.
4764		5548
4765	=item callback	5549	=item callback
4766		5550
4767	The address of a function that is called when some event has been	5551	The address of a function that is called when some event has been
4768	detected. Callbacks are being passed the event loop, the watcher that	5552	detected. Callbacks are being passed the event loop, the watcher that
4769	received the event, and the actual event bitset.	5553	received the event, and the actual event bitset.
4770		5554
4771	=item callback invocation	5555	=item callback/watcher invocation
4772		5556
4773	The act of calling the callback associated with a watcher.	5557	The act of calling the callback associated with a watcher.
4774		5558
4775	=item event	5559	=item event
4776		5560
…		…
4795	The model used to describe how an event loop handles and processes	5579	The model used to describe how an event loop handles and processes
4796	watchers and events.	5580	watchers and events.
4797		5581
4798	=item pending	5582	=item pending
4799		5583
4800	A watcher is pending as soon as the corresponding event has been detected,	5584	A watcher is pending as soon as the corresponding event has been
4801	and stops being pending as soon as the watcher will be invoked or its	5585	detected. See L</WATCHER STATES> for details.
4802	pending status is explicitly cleared by the application.
4803
4804	A watcher can be pending, but not active. Stopping a watcher also clears
4805	its pending status.
4806		5586
4807	=item real time	5587	=item real time
4808		5588
4809	The physical time that is observed. It is apparently strictly monotonic :)	5589	The physical time that is observed. It is apparently strictly monotonic :)
4810		5590
4811	=item wall-clock time	5591	=item wall-clock time
4812		5592
4813	The time and date as shown on clocks. Unlike real time, it can actually	5593	The time and date as shown on clocks. Unlike real time, it can actually
4814	be wrong and jump forwards and backwards, e.g. when the you adjust your	5594	be wrong and jump forwards and backwards, e.g. when you adjust your
4815	clock.	5595	clock.
4816		5596
4817	=item watcher	5597	=item watcher
4818		5598
4819	A data structure that describes interest in certain events. Watchers need	5599	A data structure that describes interest in certain events. Watchers need
4820	to be started (attached to an event loop) before they can receive events.	5600	to be started (attached to an event loop) before they can receive events.
4821		5601
4822	=item watcher invocation
4823
4824	The act of calling the callback associated with a watcher.
4825
4826	=back	5602	=back
4827		5603
4828	=head1 AUTHOR	5604	=head1 AUTHOR
4829		5605
4830	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson.	5606	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael
		5607	Magnusson and Emanuele Giaquinta, and minor corrections by many others.
4831		5608

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