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Revision 1.416 by root, Sun May 6 13:42:10 2012 UTC

…		…
26	puts ("stdin ready");	26	puts ("stdin ready");
27	// for one-shot events, one must manually stop the watcher	27	// for one-shot events, one must manually stop the watcher
28	// with its corresponding stop function.	28	// with its corresponding stop function.
29	ev_io_stop (EV_A_ w);	29	ev_io_stop (EV_A_ w);
30		30
31	// this causes all nested ev_loop's to stop iterating	31	// this causes all nested ev_run's to stop iterating
32	ev_unloop (EV_A_ EVUNLOOP_ALL);	32	ev_break (EV_A_ EVBREAK_ALL);
33	}	33	}
34		34
35	// another callback, this time for a time-out	35	// another callback, this time for a time-out
36	static void	36	static void
37	timeout_cb (EV_P_ ev_timer *w, int revents)	37	timeout_cb (EV_P_ ev_timer *w, int revents)
38	{	38	{
39	puts ("timeout");	39	puts ("timeout");
40	// this causes the innermost ev_loop to stop iterating	40	// this causes the innermost ev_run to stop iterating
41	ev_unloop (EV_A_ EVUNLOOP_ONE);	41	ev_break (EV_A_ EVBREAK_ONE);
42	}	42	}
43		43
44	int	44	int
45	main (void)	45	main (void)
46	{	46	{
47	// use the default event loop unless you have special needs	47	// use the default event loop unless you have special needs
48	struct ev_loop *loop = ev_default_loop (0);	48	struct ev_loop *loop = EV_DEFAULT;
49		49
50	// initialise an io watcher, then start it	50	// initialise an io watcher, then start it
51	// this one will watch for stdin to become readable	51	// this one will watch for stdin to become readable
52	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);	52	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);
53	ev_io_start (loop, &stdin_watcher);	53	ev_io_start (loop, &stdin_watcher);
…		…
56	// simple non-repeating 5.5 second timeout	56	// simple non-repeating 5.5 second timeout
57	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);	57	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
58	ev_timer_start (loop, &timeout_watcher);	58	ev_timer_start (loop, &timeout_watcher);
59		59
60	// now wait for events to arrive	60	// now wait for events to arrive
61	ev_loop (loop, 0);	61	ev_run (loop, 0);
62		62
63	// unloop was called, so exit	63	// break was called, so exit
64	return 0;	64	return 0;
65	}	65	}
66		66
67	=head1 ABOUT THIS DOCUMENT	67	=head1 ABOUT THIS DOCUMENT
68		68
…		…
75	While this document tries to be as complete as possible in documenting	75	While this document tries to be as complete as possible in documenting
76	libev, its usage and the rationale behind its design, it is not a tutorial	76	libev, its usage and the rationale behind its design, it is not a tutorial
77	on event-based programming, nor will it introduce event-based programming	77	on event-based programming, nor will it introduce event-based programming
78	with libev.	78	with libev.
79		79
80	Familarity with event based programming techniques in general is assumed	80	Familiarity with event based programming techniques in general is assumed
81	throughout this document.	81	throughout this document.
		82
		83	=head1 WHAT TO READ WHEN IN A HURRY
		84
		85	This manual tries to be very detailed, but unfortunately, this also makes
		86	it very long. If you just want to know the basics of libev, I suggest
		87	reading L</ANATOMY OF A WATCHER>, then the L</EXAMPLE PROGRAM> above and
		88	look up the missing functions in L</GLOBAL FUNCTIONS> and the C<ev_io> and
		89	C<ev_timer> sections in L</WATCHER TYPES>.
82		90
83	=head1 ABOUT LIBEV	91	=head1 ABOUT LIBEV
84		92
85	Libev is an event loop: you register interest in certain events (such as a	93	Libev is an event loop: you register interest in certain events (such as a
86	file descriptor being readable or a timeout occurring), and it will manage	94	file descriptor being readable or a timeout occurring), and it will manage
…		…
124	this argument.	132	this argument.
125		133
126	=head2 TIME REPRESENTATION	134	=head2 TIME REPRESENTATION
127		135
128	Libev represents time as a single floating point number, representing	136	Libev represents time as a single floating point number, representing
129	the (fractional) number of seconds since the (POSIX) epoch (somewhere	137	the (fractional) number of seconds since the (POSIX) epoch (in practice
130	near the beginning of 1970, details are complicated, don't ask). This	138	somewhere near the beginning of 1970, details are complicated, don't
131	type is called C<ev_tstamp>, which is what you should use too. It usually	139	ask). This type is called C<ev_tstamp>, which is what you should use
132	aliases to the C<double> type in C. When you need to do any calculations	140	too. It usually aliases to the C<double> type in C. When you need to do
133	on it, you should treat it as some floating point value. Unlike the name	141	any calculations on it, you should treat it as some floating point value.
		142
134	component C<stamp> might indicate, it is also used for time differences	143	Unlike the name component C<stamp> might indicate, it is also used for
135	throughout libev.	144	time differences (e.g. delays) throughout libev.
136		145
137	=head1 ERROR HANDLING	146	=head1 ERROR HANDLING
138		147
139	Libev knows three classes of errors: operating system errors, usage errors	148	Libev knows three classes of errors: operating system errors, usage errors
140	and internal errors (bugs).	149	and internal errors (bugs).
…		…
164		173
165	=item ev_tstamp ev_time ()	174	=item ev_tstamp ev_time ()
166		175
167	Returns the current time as libev would use it. Please note that the	176	Returns the current time as libev would use it. Please note that the
168	C<ev_now> function is usually faster and also often returns the timestamp	177	C<ev_now> function is usually faster and also often returns the timestamp
169	you actually want to know.	178	you actually want to know. Also interesting is the combination of
		179	C<ev_now_update> and C<ev_now>.
170		180
171	=item ev_sleep (ev_tstamp interval)	181	=item ev_sleep (ev_tstamp interval)
172		182
173	Sleep for the given interval: The current thread will be blocked until	183	Sleep for the given interval: The current thread will be blocked
174	either it is interrupted or the given time interval has passed. Basically	184	until either it is interrupted or the given time interval has
		185	passed (approximately - it might return a bit earlier even if not
		186	interrupted). Returns immediately if C<< interval <= 0 >>.
		187
175	this is a sub-second-resolution C<sleep ()>.	188	Basically this is a sub-second-resolution C<sleep ()>.
		189
		190	The range of the C<interval> is limited - libev only guarantees to work
		191	with sleep times of up to one day (C<< interval <= 86400 >>).
176		192
177	=item int ev_version_major ()	193	=item int ev_version_major ()
178		194
179	=item int ev_version_minor ()	195	=item int ev_version_minor ()
180		196
…		…
191	as this indicates an incompatible change. Minor versions are usually	207	as this indicates an incompatible change. Minor versions are usually
192	compatible to older versions, so a larger minor version alone is usually	208	compatible to older versions, so a larger minor version alone is usually
193	not a problem.	209	not a problem.
194		210
195	Example: Make sure we haven't accidentally been linked against the wrong	211	Example: Make sure we haven't accidentally been linked against the wrong
196	version.	212	version (note, however, that this will not detect other ABI mismatches,
		213	such as LFS or reentrancy).
197		214
198	assert (("libev version mismatch",	215	assert (("libev version mismatch",
199	ev_version_major () == EV_VERSION_MAJOR	216	ev_version_major () == EV_VERSION_MAJOR
200	&& ev_version_minor () >= EV_VERSION_MINOR));	217	&& ev_version_minor () >= EV_VERSION_MINOR));
201		218
…		…
212	assert (("sorry, no epoll, no sex",	229	assert (("sorry, no epoll, no sex",
213	ev_supported_backends () & EVBACKEND_EPOLL));	230	ev_supported_backends () & EVBACKEND_EPOLL));
214		231
215	=item unsigned int ev_recommended_backends ()	232	=item unsigned int ev_recommended_backends ()
216		233
217	Return the set of all backends compiled into this binary of libev and also	234	Return the set of all backends compiled into this binary of libev and
218	recommended for this platform. This set is often smaller than the one	235	also recommended for this platform, meaning it will work for most file
		236	descriptor types. This set is often smaller than the one returned by
219	returned by C<ev_supported_backends>, as for example kqueue is broken on	237	C<ev_supported_backends>, as for example kqueue is broken on most BSDs
220	most BSDs and will not be auto-detected unless you explicitly request it	238	and will not be auto-detected unless you explicitly request it (assuming
221	(assuming you know what you are doing). This is the set of backends that	239	you know what you are doing). This is the set of backends that libev will
222	libev will probe for if you specify no backends explicitly.	240	probe for if you specify no backends explicitly.
223		241
224	=item unsigned int ev_embeddable_backends ()	242	=item unsigned int ev_embeddable_backends ()
225		243
226	Returns the set of backends that are embeddable in other event loops. This	244	Returns the set of backends that are embeddable in other event loops. This
227	is the theoretical, all-platform, value. To find which backends	245	value is platform-specific but can include backends not available on the
228	might be supported on the current system, you would need to look at	246	current system. To find which embeddable backends might be supported on
229	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for	247	the current system, you would need to look at C<ev_embeddable_backends ()
230	recommended ones.	248	& ev_supported_backends ()>, likewise for recommended ones.
231		249
232	See the description of C<ev_embed> watchers for more info.	250	See the description of C<ev_embed> watchers for more info.
233		251
234	=item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT]	252	=item ev_set_allocator (void *(*cb)(void *ptr, long size) throw ())
235		253
236	Sets the allocation function to use (the prototype is similar - the	254	Sets the allocation function to use (the prototype is similar - the
237	semantics are identical to the C<realloc> C89/SuS/POSIX function). It is	255	semantics are identical to the C<realloc> C89/SuS/POSIX function). It is
238	used to allocate and free memory (no surprises here). If it returns zero	256	used to allocate and free memory (no surprises here). If it returns zero
239	when memory needs to be allocated (C<size != 0>), the library might abort	257	when memory needs to be allocated (C<size != 0>), the library might abort
…		…
265	}	283	}
266		284
267	...	285	...
268	ev_set_allocator (persistent_realloc);	286	ev_set_allocator (persistent_realloc);
269		287
270	=item ev_set_syserr_cb (void (*cb)(const char *msg)); [NOT REENTRANT]	288	=item ev_set_syserr_cb (void (*cb)(const char *msg) throw ())
271		289
272	Set the callback function to call on a retryable system call error (such	290	Set the callback function to call on a retryable system call error (such
273	as failed select, poll, epoll_wait). The message is a printable string	291	as failed select, poll, epoll_wait). The message is a printable string
274	indicating the system call or subsystem causing the problem. If this	292	indicating the system call or subsystem causing the problem. If this
275	callback is set, then libev will expect it to remedy the situation, no	293	callback is set, then libev will expect it to remedy the situation, no
…		…
287	}	305	}
288		306
289	...	307	...
290	ev_set_syserr_cb (fatal_error);	308	ev_set_syserr_cb (fatal_error);
291		309
		310	=item ev_feed_signal (int signum)
		311
		312	This function can be used to "simulate" a signal receive. It is completely
		313	safe to call this function at any time, from any context, including signal
		314	handlers or random threads.
		315
		316	Its main use is to customise signal handling in your process, especially
		317	in the presence of threads. For example, you could block signals
		318	by default in all threads (and specifying C<EVFLAG_NOSIGMASK> when
		319	creating any loops), and in one thread, use C<sigwait> or any other
		320	mechanism to wait for signals, then "deliver" them to libev by calling
		321	C<ev_feed_signal>.
		322
292	=back	323	=back
293		324
294	=head1 FUNCTIONS CONTROLLING THE EVENT LOOP	325	=head1 FUNCTIONS CONTROLLING EVENT LOOPS
295		326
296	An event loop is described by a C<struct ev_loop *> (the C<struct>	327	An event loop is described by a C<struct ev_loop *> (the C<struct> is
297	is I<not> optional in this case, as there is also an C<ev_loop>	328	I<not> optional in this case unless libev 3 compatibility is disabled, as
298	I<function>).	329	libev 3 had an C<ev_loop> function colliding with the struct name).
299		330
300	The library knows two types of such loops, the I<default> loop, which	331	The library knows two types of such loops, the I<default> loop, which
301	supports signals and child events, and dynamically created loops which do	332	supports child process events, and dynamically created event loops which
302	not.	333	do not.
303		334
304	=over 4	335	=over 4
305		336
306	=item struct ev_loop *ev_default_loop (unsigned int flags)	337	=item struct ev_loop *ev_default_loop (unsigned int flags)
307		338
308	This will initialise the default event loop if it hasn't been initialised	339	This returns the "default" event loop object, which is what you should
309	yet and return it. If the default loop could not be initialised, returns	340	normally use when you just need "the event loop". Event loop objects and
310	false. If it already was initialised it simply returns it (and ignores the	341	the C<flags> parameter are described in more detail in the entry for
311	flags. If that is troubling you, check C<ev_backend ()> afterwards).	342	C<ev_loop_new>.
		343
		344	If the default loop is already initialised then this function simply
		345	returns it (and ignores the flags. If that is troubling you, check
		346	C<ev_backend ()> afterwards). Otherwise it will create it with the given
		347	flags, which should almost always be C<0>, unless the caller is also the
		348	one calling C<ev_run> or otherwise qualifies as "the main program".
312		349
313	If you don't know what event loop to use, use the one returned from this	350	If you don't know what event loop to use, use the one returned from this
314	function.	351	function (or via the C<EV_DEFAULT> macro).
315		352
316	Note that this function is I<not> thread-safe, so if you want to use it	353	Note that this function is I<not> thread-safe, so if you want to use it
317	from multiple threads, you have to lock (note also that this is unlikely,	354	from multiple threads, you have to employ some kind of mutex (note also
318	as loops cannot be shared easily between threads anyway).	355	that this case is unlikely, as loops cannot be shared easily between
		356	threads anyway).
319		357
320	The default loop is the only loop that can handle C<ev_signal> and	358	The default loop is the only loop that can handle C<ev_child> watchers,
321	C<ev_child> watchers, and to do this, it always registers a handler	359	and to do this, it always registers a handler for C<SIGCHLD>. If this is
322	for C<SIGCHLD>. If this is a problem for your application you can either	360	a problem for your application you can either create a dynamic loop with
323	create a dynamic loop with C<ev_loop_new> that doesn't do that, or you	361	C<ev_loop_new> which doesn't do that, or you can simply overwrite the
324	can simply overwrite the C<SIGCHLD> signal handler I<after> calling	362	C<SIGCHLD> signal handler I<after> calling C<ev_default_init>.
325	C<ev_default_init>.	363
		364	Example: This is the most typical usage.
		365
		366	if (!ev_default_loop (0))
		367	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
		368
		369	Example: Restrict libev to the select and poll backends, and do not allow
		370	environment settings to be taken into account:
		371
		372	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
		373
		374	=item struct ev_loop *ev_loop_new (unsigned int flags)
		375
		376	This will create and initialise a new event loop object. If the loop
		377	could not be initialised, returns false.
		378
		379	This function is thread-safe, and one common way to use libev with
		380	threads is indeed to create one loop per thread, and using the default
		381	loop in the "main" or "initial" thread.
326		382
327	The flags argument can be used to specify special behaviour or specific	383	The flags argument can be used to specify special behaviour or specific
328	backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>).	384	backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>).
329		385
330	The following flags are supported:	386	The following flags are supported:
…		…
345	useful to try out specific backends to test their performance, or to work	401	useful to try out specific backends to test their performance, or to work
346	around bugs.	402	around bugs.
347		403
348	=item C<EVFLAG_FORKCHECK>	404	=item C<EVFLAG_FORKCHECK>
349		405
350	Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after	406	Instead of calling C<ev_loop_fork> manually after a fork, you can also
351	a fork, you can also make libev check for a fork in each iteration by	407	make libev check for a fork in each iteration by enabling this flag.
352	enabling this flag.
353		408
354	This works by calling C<getpid ()> on every iteration of the loop,	409	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	410	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	411	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	412	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence
…		…
366	environment variable.	421	environment variable.
367		422
368	=item C<EVFLAG_NOINOTIFY>	423	=item C<EVFLAG_NOINOTIFY>
369		424
370	When this flag is specified, then libev will not attempt to use the	425	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	426	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	427	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.	428	otherwise each loop using C<ev_stat> watchers consumes one inotify handle.
374		429
375	=item C<EVFLAG_SIGNALFD>	430	=item C<EVFLAG_SIGNALFD>
376		431
377	When this flag is specified, then libev will attempt to use the	432	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	433	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	434	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	435	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	436	handling with threads, as long as you properly block signals in your
382	threads that are not interested in handling them.	437	threads that are not interested in handling them.
383		438
384	Signalfd will not be used by default as this changes your signal mask, and	439	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	440	there are a lot of shoddy libraries and programs (glib's threadpool for
386	example) that can't properly initialise their signal masks.	441	example) that can't properly initialise their signal masks.
		442
		443	=item C<EVFLAG_NOSIGMASK>
		444
		445	When this flag is specified, then libev will avoid to modify the signal
		446	mask. Specifically, this means you have to make sure signals are unblocked
		447	when you want to receive them.
		448
		449	This behaviour is useful when you want to do your own signal handling, or
		450	want to handle signals only in specific threads and want to avoid libev
		451	unblocking the signals.
		452
		453	It's also required by POSIX in a threaded program, as libev calls
		454	C<sigprocmask>, whose behaviour is officially unspecified.
		455
		456	This flag's behaviour will become the default in future versions of libev.
387		457
388	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	458	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
389		459
390	This is your standard select(2) backend. Not I<completely> standard, as	460	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,	461	libev tries to roll its own fd_set with no limits on the number of fds,
…		…
419	=item C<EVBACKEND_EPOLL> (value 4, Linux)	489	=item C<EVBACKEND_EPOLL> (value 4, Linux)
420		490
421	Use the linux-specific epoll(7) interface (for both pre- and post-2.6.9	491	Use the linux-specific epoll(7) interface (for both pre- and post-2.6.9
422	kernels).	492	kernels).
423		493
424	For few fds, this backend is a bit little slower than poll and select,	494	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	495	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),	496	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).	497	fd), epoll scales either O(1) or O(active_fds).
428		498
429	The epoll mechanism deserves honorable mention as the most misdesigned	499	The epoll mechanism deserves honorable mention as the most misdesigned
430	of the more advanced event mechanisms: mere annoyances include silently	500	of the more advanced event mechanisms: mere annoyances include silently
431	dropping file descriptors, requiring a system call per change per file	501	dropping file descriptors, requiring a system call per change per file
432	descriptor (and unnecessary guessing of parameters), problems with dup and	502	descriptor (and unnecessary guessing of parameters), problems with dup,
		503	returning before the timeout value, resulting in additional iterations
		504	(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	505	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	506	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	507	set, which can take considerable time (one syscall per file descriptor)
436	hard to detect.	508	and is of course hard to detect.
437		509
438	Epoll is also notoriously buggy - embedding epoll fds I<should> work, but	510	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	511	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	512	totally I<different> file descriptors (even already closed ones, so
441	even remove them from the set) than registered in the set (especially	513	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	514	(especially on SMP systems). Libev tries to counter these spurious
443	employing an additional generation counter and comparing that against the	515	notifications by employing an additional generation counter and comparing
444	events to filter out spurious ones, recreating the set when required.	516	that against the events to filter out spurious ones, recreating the set
		517	when required. Epoll also erroneously rounds down timeouts, but gives you
		518	no way to know when and by how much, so sometimes you have to busy-wait
		519	because epoll returns immediately despite a nonzero timeout. And last
		520	not least, it also refuses to work with some file descriptors which work
		521	perfectly fine with C<select> (files, many character devices...).
		522
		523	Epoll is truly the train wreck among event poll mechanisms, a frankenpoll,
		524	cobbled together in a hurry, no thought to design or interaction with
		525	others. Oh, the pain, will it ever stop...
445		526
446	While stopping, setting and starting an I/O watcher in the same iteration	527	While stopping, setting and starting an I/O watcher in the same iteration
447	will result in some caching, there is still a system call per such	528	will result in some caching, there is still a system call per such
448	incident (because the same I<file descriptor> could point to a different	529	incident (because the same I<file descriptor> could point to a different
449	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed	530	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed
…		…
486		567
487	It scales in the same way as the epoll backend, but the interface to the	568	It scales in the same way as the epoll backend, but the interface to the
488	kernel is more efficient (which says nothing about its actual speed, of	569	kernel is more efficient (which says nothing about its actual speed, of
489	course). While stopping, setting and starting an I/O watcher does never	570	course). While stopping, setting and starting an I/O watcher does never
490	cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to	571	cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to
491	two event changes per incident. Support for C<fork ()> is very bad (but	572	two event changes per incident. Support for C<fork ()> is very bad (you
492	sane, unlike epoll) and it drops fds silently in similarly hard-to-detect	573	might have to leak fd's on fork, but it's more sane than epoll) and it
493	cases	574	drops fds silently in similarly hard-to-detect cases
494		575
495	This backend usually performs well under most conditions.	576	This backend usually performs well under most conditions.
496		577
497	While nominally embeddable in other event loops, this doesn't work	578	While nominally embeddable in other event loops, this doesn't work
498	everywhere, so you might need to test for this. And since it is broken	579	everywhere, so you might need to test for this. And since it is broken
…		…
515	=item C<EVBACKEND_PORT> (value 32, Solaris 10)	596	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
516		597
517	This uses the Solaris 10 event port mechanism. As with everything on Solaris,	598	This uses the Solaris 10 event port mechanism. As with everything on Solaris,
518	it's really slow, but it still scales very well (O(active_fds)).	599	it's really slow, but it still scales very well (O(active_fds)).
519		600
520	Please note that Solaris event ports can deliver a lot of spurious
521	notifications, so you need to use non-blocking I/O or other means to avoid
522	blocking when no data (or space) is available.
523
524	While this backend scales well, it requires one system call per active	601	While this backend scales well, it requires one system call per active
525	file descriptor per loop iteration. For small and medium numbers of file	602	file descriptor per loop iteration. For small and medium numbers of file
526	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend	603	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend
527	might perform better.	604	might perform better.
528		605
529	On the positive side, with the exception of the spurious readiness	606	On the positive side, this backend actually performed fully to
530	notifications, this backend actually performed fully to specification
531	in all tests and is fully embeddable, which is a rare feat among the	607	specification in all tests and is fully embeddable, which is a rare feat
532	OS-specific backends (I vastly prefer correctness over speed hacks).	608	among the OS-specific backends (I vastly prefer correctness over speed
		609	hacks).
		610
		611	On the negative side, the interface is I<bizarre> - so bizarre that
		612	even sun itself gets it wrong in their code examples: The event polling
		613	function sometimes returns events to the caller even though an error
		614	occurred, but with no indication whether it has done so or not (yes, it's
		615	even documented that way) - deadly for edge-triggered interfaces where you
		616	absolutely have to know whether an event occurred or not because you have
		617	to re-arm the watcher.
		618
		619	Fortunately libev seems to be able to work around these idiocies.
533		620
534	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as	621	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as
535	C<EVBACKEND_POLL>.	622	C<EVBACKEND_POLL>.
536		623
537	=item C<EVBACKEND_ALL>	624	=item C<EVBACKEND_ALL>
538		625
539	Try all backends (even potentially broken ones that wouldn't be tried	626	Try all backends (even potentially broken ones that wouldn't be tried
540	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as	627	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as
541	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.	628	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.
542		629
543	It is definitely not recommended to use this flag.	630	It is definitely not recommended to use this flag, use whatever
		631	C<ev_recommended_backends ()> returns, or simply do not specify a backend
		632	at all.
		633
		634	=item C<EVBACKEND_MASK>
		635
		636	Not a backend at all, but a mask to select all backend bits from a
		637	C<flags> value, in case you want to mask out any backends from a flags
		638	value (e.g. when modifying the C<LIBEV_FLAGS> environment variable).
544		639
545	=back	640	=back
546		641
547	If one or more of the backend flags are or'ed into the flags value,	642	If one or more of the backend flags are or'ed into the flags value,
548	then only these backends will be tried (in the reverse order as listed	643	then only these backends will be tried (in the reverse order as listed
549	here). If none are specified, all backends in C<ev_recommended_backends	644	here). If none are specified, all backends in C<ev_recommended_backends
550	()> will be tried.	645	()> will be tried.
551		646
552	Example: This is the most typical usage.
553
554	if (!ev_default_loop (0))
555	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
556
557	Example: Restrict libev to the select and poll backends, and do not allow
558	environment settings to be taken into account:
559
560	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
561
562	Example: Use whatever libev has to offer, but make sure that kqueue is
563	used if available (warning, breaks stuff, best use only with your own
564	private event loop and only if you know the OS supports your types of
565	fds):
566
567	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
568
569	=item struct ev_loop *ev_loop_new (unsigned int flags)
570
571	Similar to C<ev_default_loop>, but always creates a new event loop that is
572	always distinct from the default loop. Unlike the default loop, it cannot
573	handle signal and child watchers, and attempts to do so will be greeted by
574	undefined behaviour (or a failed assertion if assertions are enabled).
575
576	Note that this function I<is> thread-safe, and the recommended 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.	647	Example: Try to create a event loop that uses epoll and nothing else.
581		648
582	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	649	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
583	if (!epoller)	650	if (!epoller)
584	fatal ("no epoll found here, maybe it hides under your chair");	651	fatal ("no epoll found here, maybe it hides under your chair");
585		652
		653	Example: Use whatever libev has to offer, but make sure that kqueue is
		654	used if available.
		655
		656	struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE);
		657
586	=item ev_default_destroy ()	658	=item ev_loop_destroy (loop)
587		659
588	Destroys the default loop again (frees all memory and kernel state	660	Destroys an event loop object (frees all memory and kernel state
589	etc.). None of the active event watchers will be stopped in the normal	661	etc.). None of the active event watchers will be stopped in the normal
590	sense, so e.g. C<ev_is_active> might still return true. It is your	662	sense, so e.g. C<ev_is_active> might still return true. It is your
591	responsibility to either stop all watchers cleanly yourself I<before>	663	responsibility to either stop all watchers cleanly yourself I<before>
592	calling this function, or cope with the fact afterwards (which is usually	664	calling this function, or cope with the fact afterwards (which is usually
593	the easiest thing, you can just ignore the watchers and/or C<free ()> them	665	the easiest thing, you can just ignore the watchers and/or C<free ()> them
…		…
595		667
596	Note that certain global state, such as signal state (and installed signal	668	Note that certain global state, such as signal state (and installed signal
597	handlers), will not be freed by this function, and related watchers (such	669	handlers), will not be freed by this function, and related watchers (such
598	as signal and child watchers) would need to be stopped manually.	670	as signal and child watchers) would need to be stopped manually.
599		671
600	In general it is not advisable to call this function except in the	672	This function is normally used on loop objects allocated by
601	rare occasion where you really need to free e.g. the signal handling	673	C<ev_loop_new>, but it can also be used on the default loop returned by
		674	C<ev_default_loop>, in which case it is not thread-safe.
		675
		676	Note that it is not advisable to call this function on the default loop
		677	except in the rare occasion where you really need to free its resources.
602	pipe fds. If you need dynamically allocated loops it is better to use	678	If you need dynamically allocated loops it is better to use C<ev_loop_new>
603	C<ev_loop_new> and C<ev_loop_destroy>.	679	and C<ev_loop_destroy>.
604		680
605	=item ev_loop_destroy (loop)	681	=item ev_loop_fork (loop)
606		682
607	Like C<ev_default_destroy>, but destroys an event loop created by an
608	earlier call to C<ev_loop_new>.
609
610	=item ev_default_fork ()
611
612	This function sets a flag that causes subsequent C<ev_loop> iterations	683	This function sets a flag that causes subsequent C<ev_run> iterations to
613	to reinitialise the kernel state for backends that have one. Despite the	684	reinitialise the kernel state for backends that have one. Despite the
614	name, you can call it anytime, but it makes most sense after forking, in	685	name, you can call it anytime, but it makes most sense after forking, in
615	the child process (or both child and parent, but that again makes little	686	the child process. You I<must> call it (or use C<EVFLAG_FORKCHECK>) in the
616	sense). You I<must> call it in the child before using any of the libev	687	child before resuming or calling C<ev_run>.
617	functions, and it will only take effect at the next C<ev_loop> iteration.	688
		689	Again, you I<have> to call it on I<any> loop that you want to re-use after
		690	a fork, I<even if you do not plan to use the loop in the parent>. This is
		691	because some kernel interfaces *cough* I<kqueue> *cough* do funny things
		692	during fork.
618		693
619	On the other hand, you only need to call this function in the child	694	On the other hand, you only need to call this function in the child
620	process if and only if you want to use the event library in the child. If	695	process if and only if you want to use the event loop in the child. If
621	you just fork+exec, you don't have to call it at all.	696	you just fork+exec or create a new loop in the child, you don't have to
		697	call it at all (in fact, C<epoll> is so badly broken that it makes a
		698	difference, but libev will usually detect this case on its own and do a
		699	costly reset of the backend).
622		700
623	The function itself is quite fast and it's usually not a problem to call	701	The function itself is quite fast and it's usually not a problem to call
624	it just in case after a fork. To make this easy, the function will fit in	702	it just in case after a fork.
625	quite nicely into a call to C<pthread_atfork>:
626		703
		704	Example: Automate calling C<ev_loop_fork> on the default loop when
		705	using pthreads.
		706
		707	static void
		708	post_fork_child (void)
		709	{
		710	ev_loop_fork (EV_DEFAULT);
		711	}
		712
		713	...
627	pthread_atfork (0, 0, ev_default_fork);	714	pthread_atfork (0, 0, post_fork_child);
628
629	=item ev_loop_fork (loop)
630
631	Like C<ev_default_fork>, but acts on an event loop created by
632	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
633	after fork that you want to re-use in the child, and how you do this is
634	entirely your own problem.
635		715
636	=item int ev_is_default_loop (loop)	716	=item int ev_is_default_loop (loop)
637		717
638	Returns true when the given loop is, in fact, the default loop, and false	718	Returns true when the given loop is, in fact, the default loop, and false
639	otherwise.	719	otherwise.
640		720
641	=item unsigned int ev_loop_count (loop)	721	=item unsigned int ev_iteration (loop)
642		722
643	Returns the count of loop iterations for the loop, which is identical to	723	Returns the current iteration count for the event loop, which is identical
644	the number of times libev did poll for new events. It starts at C<0> and	724	to the number of times libev did poll for new events. It starts at C<0>
645	happily wraps around with enough iterations.	725	and happily wraps around with enough iterations.
646		726
647	This value can sometimes be useful as a generation counter of sorts (it	727	This value can sometimes be useful as a generation counter of sorts (it
648	"ticks" the number of loop iterations), as it roughly corresponds with	728	"ticks" the number of loop iterations), as it roughly corresponds with
649	C<ev_prepare> and C<ev_check> calls.	729	C<ev_prepare> and C<ev_check> calls - and is incremented between the
		730	prepare and check phases.
650		731
651	=item unsigned int ev_loop_depth (loop)	732	=item unsigned int ev_depth (loop)
652		733
653	Returns the number of times C<ev_loop> was entered minus the number of	734	Returns the number of times C<ev_run> was entered minus the number of
654	times C<ev_loop> was exited, in other words, the recursion depth.	735	times C<ev_run> was exited normally, in other words, the recursion depth.
655		736
656	Outside C<ev_loop>, this number is zero. In a callback, this number is	737	Outside C<ev_run>, this number is zero. In a callback, this number is
657	C<1>, unless C<ev_loop> was invoked recursively (or from another thread),	738	C<1>, unless C<ev_run> was invoked recursively (or from another thread),
658	in which case it is higher.	739	in which case it is higher.
659		740
660	Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread	741	Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread,
661	etc.), doesn't count as exit.	742	throwing an exception etc.), doesn't count as "exit" - consider this
		743	as a hint to avoid such ungentleman-like behaviour unless it's really
		744	convenient, in which case it is fully supported.
662		745
663	=item unsigned int ev_backend (loop)	746	=item unsigned int ev_backend (loop)
664		747
665	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	748	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
666	use.	749	use.
…		…
675		758
676	=item ev_now_update (loop)	759	=item ev_now_update (loop)
677		760
678	Establishes the current time by querying the kernel, updating the time	761	Establishes the current time by querying the kernel, updating the time
679	returned by C<ev_now ()> in the progress. This is a costly operation and	762	returned by C<ev_now ()> in the progress. This is a costly operation and
680	is usually done automatically within C<ev_loop ()>.	763	is usually done automatically within C<ev_run ()>.
681		764
682	This function is rarely useful, but when some event callback runs for a	765	This function is rarely useful, but when some event callback runs for a
683	very long time without entering the event loop, updating libev's idea of	766	very long time without entering the event loop, updating libev's idea of
684	the current time is a good idea.	767	the current time is a good idea.
685		768
686	See also L<The special problem of time updates> in the C<ev_timer> section.	769	See also L</The special problem of time updates> in the C<ev_timer> section.
687		770
688	=item ev_suspend (loop)	771	=item ev_suspend (loop)
689		772
690	=item ev_resume (loop)	773	=item ev_resume (loop)
691		774
692	These two functions suspend and resume a loop, for use when the loop is	775	These two functions suspend and resume an event loop, for use when the
693	not used for a while and timeouts should not be processed.	776	loop is not used for a while and timeouts should not be processed.
694		777
695	A typical use case would be an interactive program such as a game: When	778	A typical use case would be an interactive program such as a game: When
696	the user presses C<^Z> to suspend the game and resumes it an hour later it	779	the user presses C<^Z> to suspend the game and resumes it an hour later it
697	would be best to handle timeouts as if no time had actually passed while	780	would be best to handle timeouts as if no time had actually passed while
698	the program was suspended. This can be achieved by calling C<ev_suspend>	781	the program was suspended. This can be achieved by calling C<ev_suspend>
…		…
700	C<ev_resume> directly afterwards to resume timer processing.	783	C<ev_resume> directly afterwards to resume timer processing.
701		784
702	Effectively, all C<ev_timer> watchers will be delayed by the time spend	785	Effectively, all C<ev_timer> watchers will be delayed by the time spend
703	between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers	786	between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers
704	will be rescheduled (that is, they will lose any events that would have	787	will be rescheduled (that is, they will lose any events that would have
705	occured while suspended).	788	occurred while suspended).
706		789
707	After calling C<ev_suspend> you B<must not> call I<any> function on the	790	After calling C<ev_suspend> you B<must not> call I<any> function on the
708	given loop other than C<ev_resume>, and you B<must not> call C<ev_resume>	791	given loop other than C<ev_resume>, and you B<must not> call C<ev_resume>
709	without a previous call to C<ev_suspend>.	792	without a previous call to C<ev_suspend>.
710		793
711	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the	794	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the
712	event loop time (see C<ev_now_update>).	795	event loop time (see C<ev_now_update>).
713		796
714	=item ev_loop (loop, int flags)	797	=item bool ev_run (loop, int flags)
715		798
716	Finally, this is it, the event handler. This function usually is called	799	Finally, this is it, the event handler. This function usually is called
717	after you have initialised all your watchers and you want to start	800	after you have initialised all your watchers and you want to start
718	handling events.	801	handling events. It will ask the operating system for any new events, call
		802	the watcher callbacks, and then repeat the whole process indefinitely: This
		803	is why event loops are called I<loops>.
719		804
720	If the flags argument is specified as C<0>, it will not return until	805	If the flags argument is specified as C<0>, it will keep handling events
721	either no event watchers are active anymore or C<ev_unloop> was called.	806	until either no event watchers are active anymore or C<ev_break> was
		807	called.
722		808
		809	The return value is false if there are no more active watchers (which
		810	usually means "all jobs done" or "deadlock"), and true in all other cases
		811	(which usually means " you should call C<ev_run> again").
		812
723	Please note that an explicit C<ev_unloop> is usually better than	813	Please note that an explicit C<ev_break> is usually better than
724	relying on all watchers to be stopped when deciding when a program has	814	relying on all watchers to be stopped when deciding when a program has
725	finished (especially in interactive programs), but having a program	815	finished (especially in interactive programs), but having a program
726	that automatically loops as long as it has to and no longer by virtue	816	that automatically loops as long as it has to and no longer by virtue
727	of relying on its watchers stopping correctly, that is truly a thing of	817	of relying on its watchers stopping correctly, that is truly a thing of
728	beauty.	818	beauty.
729		819
		820	This function is I<mostly> exception-safe - you can break out of a
		821	C<ev_run> call by calling C<longjmp> in a callback, throwing a C++
		822	exception and so on. This does not decrement the C<ev_depth> value, nor
		823	will it clear any outstanding C<EVBREAK_ONE> breaks.
		824
730	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle	825	A flags value of C<EVRUN_NOWAIT> will look for new events, will handle
731	those events and any already outstanding ones, but will not block your	826	those events and any already outstanding ones, but will not wait and
732	process in case there are no events and will return after one iteration of	827	block your process in case there are no events and will return after one
733	the loop.	828	iteration of the loop. This is sometimes useful to poll and handle new
		829	events while doing lengthy calculations, to keep the program responsive.
734		830
735	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if	831	A flags value of C<EVRUN_ONCE> will look for new events (waiting if
736	necessary) and will handle those and any already outstanding ones. It	832	necessary) and will handle those and any already outstanding ones. It
737	will block your process until at least one new event arrives (which could	833	will block your process until at least one new event arrives (which could
738	be an event internal to libev itself, so there is no guarantee that a	834	be an event internal to libev itself, so there is no guarantee that a
739	user-registered callback will be called), and will return after one	835	user-registered callback will be called), and will return after one
740	iteration of the loop.	836	iteration of the loop.
741		837
742	This is useful if you are waiting for some external event in conjunction	838	This is useful if you are waiting for some external event in conjunction
743	with something not expressible using other libev watchers (i.e. "roll your	839	with something not expressible using other libev watchers (i.e. "roll your
744	own C<ev_loop>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is	840	own C<ev_run>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is
745	usually a better approach for this kind of thing.	841	usually a better approach for this kind of thing.
746		842
747	Here are the gory details of what C<ev_loop> does:	843	Here are the gory details of what C<ev_run> does (this is for your
		844	understanding, not a guarantee that things will work exactly like this in
		845	future versions):
748		846
		847	- Increment loop depth.
		848	- Reset the ev_break status.
749	- Before the first iteration, call any pending watchers.	849	- Before the first iteration, call any pending watchers.
		850	LOOP:
750	* If EVFLAG_FORKCHECK was used, check for a fork.	851	- If EVFLAG_FORKCHECK was used, check for a fork.
751	- If a fork was detected (by any means), queue and call all fork watchers.	852	- If a fork was detected (by any means), queue and call all fork watchers.
752	- Queue and call all prepare watchers.	853	- Queue and call all prepare watchers.
		854	- If ev_break was called, goto FINISH.
753	- If we have been forked, detach and recreate the kernel state	855	- If we have been forked, detach and recreate the kernel state
754	as to not disturb the other process.	856	as to not disturb the other process.
755	- Update the kernel state with all outstanding changes.	857	- Update the kernel state with all outstanding changes.
756	- Update the "event loop time" (ev_now ()).	858	- Update the "event loop time" (ev_now ()).
757	- Calculate for how long to sleep or block, if at all	859	- Calculate for how long to sleep or block, if at all
758	(active idle watchers, EVLOOP_NONBLOCK or not having	860	(active idle watchers, EVRUN_NOWAIT or not having
759	any active watchers at all will result in not sleeping).	861	any active watchers at all will result in not sleeping).
760	- Sleep if the I/O and timer collect interval say so.	862	- Sleep if the I/O and timer collect interval say so.
		863	- Increment loop iteration counter.
761	- Block the process, waiting for any events.	864	- Block the process, waiting for any events.
762	- Queue all outstanding I/O (fd) events.	865	- Queue all outstanding I/O (fd) events.
763	- Update the "event loop time" (ev_now ()), and do time jump adjustments.	866	- Update the "event loop time" (ev_now ()), and do time jump adjustments.
764	- Queue all expired timers.	867	- Queue all expired timers.
765	- Queue all expired periodics.	868	- Queue all expired periodics.
766	- Unless any events are pending now, queue all idle watchers.	869	- Queue all idle watchers with priority higher than that of pending events.
767	- Queue all check watchers.	870	- Queue all check watchers.
768	- Call all queued watchers in reverse order (i.e. check watchers first).	871	- Call all queued watchers in reverse order (i.e. check watchers first).
769	Signals and child watchers are implemented as I/O watchers, and will	872	Signals and child watchers are implemented as I/O watchers, and will
770	be handled here by queueing them when their watcher gets executed.	873	be handled here by queueing them when their watcher gets executed.
771	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	874	- If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT
772	were used, or there are no active watchers, return, otherwise	875	were used, or there are no active watchers, goto FINISH, otherwise
773	continue with step *.	876	continue with step LOOP.
		877	FINISH:
		878	- Reset the ev_break status iff it was EVBREAK_ONE.
		879	- Decrement the loop depth.
		880	- Return.
774		881
775	Example: Queue some jobs and then loop until no events are outstanding	882	Example: Queue some jobs and then loop until no events are outstanding
776	anymore.	883	anymore.
777		884
778	... queue jobs here, make sure they register event watchers as long	885	... queue jobs here, make sure they register event watchers as long
779	... as they still have work to do (even an idle watcher will do..)	886	... as they still have work to do (even an idle watcher will do..)
780	ev_loop (my_loop, 0);	887	ev_run (my_loop, 0);
781	... jobs done or somebody called unloop. yeah!	888	... jobs done or somebody called break. yeah!
782		889
783	=item ev_unloop (loop, how)	890	=item ev_break (loop, how)
784		891
785	Can be used to make a call to C<ev_loop> return early (but only after it	892	Can be used to make a call to C<ev_run> return early (but only after it
786	has processed all outstanding events). The C<how> argument must be either	893	has processed all outstanding events). The C<how> argument must be either
787	C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or	894	C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or
788	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.	895	C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return.
789		896
790	This "unloop state" will be cleared when entering C<ev_loop> again.	897	This "break state" will be cleared on the next call to C<ev_run>.
791		898
792	It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls.	899	It is safe to call C<ev_break> from outside any C<ev_run> calls, too, in
		900	which case it will have no effect.
793		901
794	=item ev_ref (loop)	902	=item ev_ref (loop)
795		903
796	=item ev_unref (loop)	904	=item ev_unref (loop)
797		905
798	Ref/unref can be used to add or remove a reference count on the event	906	Ref/unref can be used to add or remove a reference count on the event
799	loop: Every watcher keeps one reference, and as long as the reference	907	loop: Every watcher keeps one reference, and as long as the reference
800	count is nonzero, C<ev_loop> will not return on its own.	908	count is nonzero, C<ev_run> will not return on its own.
801		909
802	This is useful when you have a watcher that you never intend to	910	This is useful when you have a watcher that you never intend to
803	unregister, but that nevertheless should not keep C<ev_loop> from	911	unregister, but that nevertheless should not keep C<ev_run> from
804	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>	912	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>
805	before stopping it.	913	before stopping it.
806		914
807	As an example, libev itself uses this for its internal signal pipe: It	915	As an example, libev itself uses this for its internal signal pipe: It
808	is not visible to the libev user and should not keep C<ev_loop> from	916	is not visible to the libev user and should not keep C<ev_run> from
809	exiting if no event watchers registered by it are active. It is also an	917	exiting if no event watchers registered by it are active. It is also an
810	excellent way to do this for generic recurring timers or from within	918	excellent way to do this for generic recurring timers or from within
811	third-party libraries. Just remember to I<unref after start> and I<ref	919	third-party libraries. Just remember to I<unref after start> and I<ref
812	before stop> (but only if the watcher wasn't active before, or was active	920	before stop> (but only if the watcher wasn't active before, or was active
813	before, respectively. Note also that libev might stop watchers itself	921	before, respectively. Note also that libev might stop watchers itself
814	(e.g. non-repeating timers) in which case you have to C<ev_ref>	922	(e.g. non-repeating timers) in which case you have to C<ev_ref>
815	in the callback).	923	in the callback).
816		924
817	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	925	Example: Create a signal watcher, but keep it from keeping C<ev_run>
818	running when nothing else is active.	926	running when nothing else is active.
819		927
820	ev_signal exitsig;	928	ev_signal exitsig;
821	ev_signal_init (&exitsig, sig_cb, SIGINT);	929	ev_signal_init (&exitsig, sig_cb, SIGINT);
822	ev_signal_start (loop, &exitsig);	930	ev_signal_start (loop, &exitsig);
823	evf_unref (loop);	931	ev_unref (loop);
824		932
825	Example: For some weird reason, unregister the above signal handler again.	933	Example: For some weird reason, unregister the above signal handler again.
826		934
827	ev_ref (loop);	935	ev_ref (loop);
828	ev_signal_stop (loop, &exitsig);	936	ev_signal_stop (loop, &exitsig);
…		…
848	overhead for the actual polling but can deliver many events at once.	956	overhead for the actual polling but can deliver many events at once.
849		957
850	By setting a higher I<io collect interval> you allow libev to spend more	958	By setting a higher I<io collect interval> you allow libev to spend more
851	time collecting I/O events, so you can handle more events per iteration,	959	time collecting I/O events, so you can handle more events per iteration,
852	at the cost of increasing latency. Timeouts (both C<ev_periodic> and	960	at the cost of increasing latency. Timeouts (both C<ev_periodic> and
853	C<ev_timer>) will be not affected. Setting this to a non-null value will	961	C<ev_timer>) will not be affected. Setting this to a non-null value will
854	introduce an additional C<ev_sleep ()> call into most loop iterations. The	962	introduce an additional C<ev_sleep ()> call into most loop iterations. The
855	sleep time ensures that libev will not poll for I/O events more often then	963	sleep time ensures that libev will not poll for I/O events more often then
856	once per this interval, on average.	964	once per this interval, on average (as long as the host time resolution is
		965	good enough).
857		966
858	Likewise, by setting a higher I<timeout collect interval> you allow libev	967	Likewise, by setting a higher I<timeout collect interval> you allow libev
859	to spend more time collecting timeouts, at the expense of increased	968	to spend more time collecting timeouts, at the expense of increased
860	latency/jitter/inexactness (the watcher callback will be called	969	latency/jitter/inexactness (the watcher callback will be called
861	later). C<ev_io> watchers will not be affected. Setting this to a non-null	970	later). C<ev_io> watchers will not be affected. Setting this to a non-null
…		…
867	usually doesn't make much sense to set it to a lower value than C<0.01>,	976	usually doesn't make much sense to set it to a lower value than C<0.01>,
868	as this approaches the timing granularity of most systems. Note that if	977	as this approaches the timing granularity of most systems. Note that if
869	you do transactions with the outside world and you can't increase the	978	you do transactions with the outside world and you can't increase the
870	parallelity, then this setting will limit your transaction rate (if you	979	parallelity, then this setting will limit your transaction rate (if you
871	need to poll once per transaction and the I/O collect interval is 0.01,	980	need to poll once per transaction and the I/O collect interval is 0.01,
872	then you can't do more than 100 transations per second).	981	then you can't do more than 100 transactions per second).
873		982
874	Setting the I<timeout collect interval> can improve the opportunity for	983	Setting the I<timeout collect interval> can improve the opportunity for
875	saving power, as the program will "bundle" timer callback invocations that	984	saving power, as the program will "bundle" timer callback invocations that
876	are "near" in time together, by delaying some, thus reducing the number of	985	are "near" in time together, by delaying some, thus reducing the number of
877	times the process sleeps and wakes up again. Another useful technique to	986	times the process sleeps and wakes up again. Another useful technique to
…		…
885	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);	994	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);
886		995
887	=item ev_invoke_pending (loop)	996	=item ev_invoke_pending (loop)
888		997
889	This call will simply invoke all pending watchers while resetting their	998	This call will simply invoke all pending watchers while resetting their
890	pending state. Normally, C<ev_loop> does this automatically when required,	999	pending state. Normally, C<ev_run> does this automatically when required,
891	but when overriding the invoke callback this call comes handy.	1000	but when overriding the invoke callback this call comes handy. This
		1001	function can be invoked from a watcher - this can be useful for example
		1002	when you want to do some lengthy calculation and want to pass further
		1003	event handling to another thread (you still have to make sure only one
		1004	thread executes within C<ev_invoke_pending> or C<ev_run> of course).
892		1005
893	=item int ev_pending_count (loop)	1006	=item int ev_pending_count (loop)
894		1007
895	Returns the number of pending watchers - zero indicates that no watchers	1008	Returns the number of pending watchers - zero indicates that no watchers
896	are pending.	1009	are pending.
897		1010
898	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))	1011	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))
899		1012
900	This overrides the invoke pending functionality of the loop: Instead of	1013	This overrides the invoke pending functionality of the loop: Instead of
901	invoking all pending watchers when there are any, C<ev_loop> will call	1014	invoking all pending watchers when there are any, C<ev_run> will call
902	this callback instead. This is useful, for example, when you want to	1015	this callback instead. This is useful, for example, when you want to
903	invoke the actual watchers inside another context (another thread etc.).	1016	invoke the actual watchers inside another context (another thread etc.).
904		1017
905	If you want to reset the callback, use C<ev_invoke_pending> as new	1018	If you want to reset the callback, use C<ev_invoke_pending> as new
906	callback.	1019	callback.
907		1020
908	=item ev_set_loop_release_cb (loop, void (*release)(EV_P), void (*acquire)(EV_P))	1021	=item ev_set_loop_release_cb (loop, void (*release)(EV_P) throw (), void (*acquire)(EV_P) throw ())
909		1022
910	Sometimes you want to share the same loop between multiple threads. This	1023	Sometimes you want to share the same loop between multiple threads. This
911	can be done relatively simply by putting mutex_lock/unlock calls around	1024	can be done relatively simply by putting mutex_lock/unlock calls around
912	each call to a libev function.	1025	each call to a libev function.
913		1026
914	However, C<ev_loop> can run an indefinite time, so it is not feasible to	1027	However, C<ev_run> can run an indefinite time, so it is not feasible
915	wait for it to return. One way around this is to wake up the loop via	1028	to wait for it to return. One way around this is to wake up the event
916	C<ev_unloop> and C<av_async_send>, another way is to set these I<release>	1029	loop via C<ev_break> and C<ev_async_send>, another way is to set these
917	and I<acquire> callbacks on the loop.	1030	I<release> and I<acquire> callbacks on the loop.
918		1031
919	When set, then C<release> will be called just before the thread is	1032	When set, then C<release> will be called just before the thread is
920	suspended waiting for new events, and C<acquire> is called just	1033	suspended waiting for new events, and C<acquire> is called just
921	afterwards.	1034	afterwards.
922		1035
…		…
925		1038
926	While event loop modifications are allowed between invocations of	1039	While event loop modifications are allowed between invocations of
927	C<release> and C<acquire> (that's their only purpose after all), no	1040	C<release> and C<acquire> (that's their only purpose after all), no
928	modifications done will affect the event loop, i.e. adding watchers will	1041	modifications done will affect the event loop, i.e. adding watchers will
929	have no effect on the set of file descriptors being watched, or the time	1042	have no effect on the set of file descriptors being watched, or the time
930	waited. Use an C<ev_async> watcher to wake up C<ev_loop> when you want it	1043	waited. Use an C<ev_async> watcher to wake up C<ev_run> when you want it
931	to take note of any changes you made.	1044	to take note of any changes you made.
932		1045
933	In theory, threads executing C<ev_loop> will be async-cancel safe between	1046	In theory, threads executing C<ev_run> will be async-cancel safe between
934	invocations of C<release> and C<acquire>.	1047	invocations of C<release> and C<acquire>.
935		1048
936	See also the locking example in the C<THREADS> section later in this	1049	See also the locking example in the C<THREADS> section later in this
937	document.	1050	document.
938		1051
939	=item ev_set_userdata (loop, void *data)	1052	=item ev_set_userdata (loop, void *data)
940		1053
941	=item ev_userdata (loop)	1054	=item void *ev_userdata (loop)
942		1055
943	Set and retrieve a single C<void *> associated with a loop. When	1056	Set and retrieve a single C<void *> associated with a loop. When
944	C<ev_set_userdata> has never been called, then C<ev_userdata> returns	1057	C<ev_set_userdata> has never been called, then C<ev_userdata> returns
945	C<0.>	1058	C<0>.
946		1059
947	These two functions can be used to associate arbitrary data with a loop,	1060	These two functions can be used to associate arbitrary data with a loop,
948	and are intended solely for the C<invoke_pending_cb>, C<release> and	1061	and are intended solely for the C<invoke_pending_cb>, C<release> and
949	C<acquire> callbacks described above, but of course can be (ab-)used for	1062	C<acquire> callbacks described above, but of course can be (ab-)used for
950	any other purpose as well.	1063	any other purpose as well.
951		1064
952	=item ev_loop_verify (loop)	1065	=item ev_verify (loop)
953		1066
954	This function only does something when C<EV_VERIFY> support has been	1067	This function only does something when C<EV_VERIFY> support has been
955	compiled in, which is the default for non-minimal builds. It tries to go	1068	compiled in, which is the default for non-minimal builds. It tries to go
956	through all internal structures and checks them for validity. If anything	1069	through all internal structures and checks them for validity. If anything
957	is found to be inconsistent, it will print an error message to standard	1070	is found to be inconsistent, it will print an error message to standard
…		…
968		1081
969	In the following description, uppercase C<TYPE> in names stands for the	1082	In the following description, uppercase C<TYPE> in names stands for the
970	watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer	1083	watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer
971	watchers and C<ev_io_start> for I/O watchers.	1084	watchers and C<ev_io_start> for I/O watchers.
972		1085
973	A watcher is a structure that you create and register to record your	1086	A watcher is an opaque structure that you allocate and register to record
974	interest in some event. For instance, if you want to wait for STDIN to	1087	your interest in some event. To make a concrete example, imagine you want
975	become readable, you would create an C<ev_io> watcher for that:	1088	to wait for STDIN to become readable, you would create an C<ev_io> watcher
		1089	for that:
976		1090
977	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)	1091	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)
978	{	1092	{
979	ev_io_stop (w);	1093	ev_io_stop (w);
980	ev_unloop (loop, EVUNLOOP_ALL);	1094	ev_break (loop, EVBREAK_ALL);
981	}	1095	}
982		1096
983	struct ev_loop *loop = ev_default_loop (0);	1097	struct ev_loop *loop = ev_default_loop (0);
984		1098
985	ev_io stdin_watcher;	1099	ev_io stdin_watcher;
986		1100
987	ev_init (&stdin_watcher, my_cb);	1101	ev_init (&stdin_watcher, my_cb);
988	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	1102	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
989	ev_io_start (loop, &stdin_watcher);	1103	ev_io_start (loop, &stdin_watcher);
990		1104
991	ev_loop (loop, 0);	1105	ev_run (loop, 0);
992		1106
993	As you can see, you are responsible for allocating the memory for your	1107	As you can see, you are responsible for allocating the memory for your
994	watcher structures (and it is I<usually> a bad idea to do this on the	1108	watcher structures (and it is I<usually> a bad idea to do this on the
995	stack).	1109	stack).
996		1110
997	Each watcher has an associated watcher structure (called C<struct ev_TYPE>	1111	Each watcher has an associated watcher structure (called C<struct ev_TYPE>
998	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).	1112	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).
999		1113
1000	Each watcher structure must be initialised by a call to C<ev_init	1114	Each watcher structure must be initialised by a call to C<ev_init (watcher
1001	(watcher *, callback)>, which expects a callback to be provided. This	1115	*, callback)>, which expects a callback to be provided. This callback is
1002	callback gets invoked each time the event occurs (or, in the case of I/O	1116	invoked each time the event occurs (or, in the case of I/O watchers, each
1003	watchers, each time the event loop detects that the file descriptor given	1117	time the event loop detects that the file descriptor given is readable
1004	is readable and/or writable).	1118	and/or writable).
1005		1119
1006	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>	1120	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>
1007	macro to configure it, with arguments specific to the watcher type. There	1121	macro to configure it, with arguments specific to the watcher type. There
1008	is also a macro to combine initialisation and setting in one call: C<<	1122	is also a macro to combine initialisation and setting in one call: C<<
1009	ev_TYPE_init (watcher *, callback, ...) >>.	1123	ev_TYPE_init (watcher *, callback, ...) >>.
…		…
1032	=item C<EV_WRITE>	1146	=item C<EV_WRITE>
1033		1147
1034	The file descriptor in the C<ev_io> watcher has become readable and/or	1148	The file descriptor in the C<ev_io> watcher has become readable and/or
1035	writable.	1149	writable.
1036		1150
1037	=item C<EV_TIMEOUT>	1151	=item C<EV_TIMER>
1038		1152
1039	The C<ev_timer> watcher has timed out.	1153	The C<ev_timer> watcher has timed out.
1040		1154
1041	=item C<EV_PERIODIC>	1155	=item C<EV_PERIODIC>
1042		1156
…		…
1060		1174
1061	=item C<EV_PREPARE>	1175	=item C<EV_PREPARE>
1062		1176
1063	=item C<EV_CHECK>	1177	=item C<EV_CHECK>
1064		1178
1065	All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts	1179	All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts to
1066	to gather new events, and all C<ev_check> watchers are invoked just after	1180	gather new events, and all C<ev_check> watchers are queued (not invoked)
1067	C<ev_loop> has gathered them, but before it invokes any callbacks for any	1181	just after C<ev_run> has gathered them, but before it queues any callbacks
		1182	for any received events. That means C<ev_prepare> watchers are the last
		1183	watchers invoked before the event loop sleeps or polls for new events, and
		1184	C<ev_check> watchers will be invoked before any other watchers of the same
		1185	or lower priority within an event loop iteration.
		1186
1068	received events. Callbacks of both watcher types can start and stop as	1187	Callbacks of both watcher types can start and stop as many watchers as
1069	many watchers as they want, and all of them will be taken into account	1188	they want, and all of them will be taken into account (for example, a
1070	(for example, a C<ev_prepare> watcher might start an idle watcher to keep	1189	C<ev_prepare> watcher might start an idle watcher to keep C<ev_run> from
1071	C<ev_loop> from blocking).	1190	blocking).
1072		1191
1073	=item C<EV_EMBED>	1192	=item C<EV_EMBED>
1074		1193
1075	The embedded event loop specified in the C<ev_embed> watcher needs attention.	1194	The embedded event loop specified in the C<ev_embed> watcher needs attention.
1076		1195
1077	=item C<EV_FORK>	1196	=item C<EV_FORK>
1078		1197
1079	The event loop has been resumed in the child process after fork (see	1198	The event loop has been resumed in the child process after fork (see
1080	C<ev_fork>).	1199	C<ev_fork>).
		1200
		1201	=item C<EV_CLEANUP>
		1202
		1203	The event loop is about to be destroyed (see C<ev_cleanup>).
1081		1204
1082	=item C<EV_ASYNC>	1205	=item C<EV_ASYNC>
1083		1206
1084	The given async watcher has been asynchronously notified (see C<ev_async>).	1207	The given async watcher has been asynchronously notified (see C<ev_async>).
1085		1208
…		…
1195		1318
1196	=item callback ev_cb (ev_TYPE *watcher)	1319	=item callback ev_cb (ev_TYPE *watcher)
1197		1320
1198	Returns the callback currently set on the watcher.	1321	Returns the callback currently set on the watcher.
1199		1322
1200	=item ev_cb_set (ev_TYPE *watcher, callback)	1323	=item ev_set_cb (ev_TYPE *watcher, callback)
1201		1324
1202	Change the callback. You can change the callback at virtually any time	1325	Change the callback. You can change the callback at virtually any time
1203	(modulo threads).	1326	(modulo threads).
1204		1327
1205	=item ev_set_priority (ev_TYPE *watcher, int priority)	1328	=item ev_set_priority (ev_TYPE *watcher, int priority)
…		…
1223	or might not have been clamped to the valid range.	1346	or might not have been clamped to the valid range.
1224		1347
1225	The default priority used by watchers when no priority has been set is	1348	The default priority used by watchers when no priority has been set is
1226	always C<0>, which is supposed to not be too high and not be too low :).	1349	always C<0>, which is supposed to not be too high and not be too low :).
1227		1350
1228	See L<WATCHER PRIORITY MODELS>, below, for a more thorough treatment of	1351	See L</WATCHER PRIORITY MODELS>, below, for a more thorough treatment of
1229	priorities.	1352	priorities.
1230		1353
1231	=item ev_invoke (loop, ev_TYPE *watcher, int revents)	1354	=item ev_invoke (loop, ev_TYPE *watcher, int revents)
1232		1355
1233	Invoke the C<watcher> with the given C<loop> and C<revents>. Neither	1356	Invoke the C<watcher> with the given C<loop> and C<revents>. Neither
…		…
1258	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related	1381	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related
1259	functions that do not need a watcher.	1382	functions that do not need a watcher.
1260		1383
1261	=back	1384	=back
1262		1385
		1386	See also the L</ASSOCIATING CUSTOM DATA WITH A WATCHER> and L</BUILDING YOUR
		1387	OWN COMPOSITE WATCHERS> idioms.
1263		1388
1264	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	1389	=head2 WATCHER STATES
1265		1390
1266	Each watcher has, by default, a member C<void *data> that you can change	1391	There are various watcher states mentioned throughout this manual -
1267	and read at any time: libev will completely ignore it. This can be used	1392	active, pending and so on. In this section these states and the rules to
1268	to associate arbitrary data with your watcher. If you need more data and	1393	transition between them will be described in more detail - and while these
1269	don't want to allocate memory and store a pointer to it in that data	1394	rules might look complicated, they usually do "the right thing".
1270	member, you can also "subclass" the watcher type and provide your own
1271	data:
1272		1395
1273	struct my_io	1396	=over 4
1274	{
1275	ev_io io;
1276	int otherfd;
1277	void *somedata;
1278	struct whatever *mostinteresting;
1279	};
1280		1397
1281	...	1398	=item initialiased
1282	struct my_io w;
1283	ev_io_init (&w.io, my_cb, fd, EV_READ);
1284		1399
1285	And since your callback will be called with a pointer to the watcher, you	1400	Before a watcher can be registered with the event loop it has to be
1286	can cast it back to your own type:	1401	initialised. This can be done with a call to C<ev_TYPE_init>, or calls to
		1402	C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function.
1287		1403
1288	static void my_cb (struct ev_loop *loop, ev_io *w_, int revents)	1404	In this state it is simply some block of memory that is suitable for
1289	{	1405	use in an event loop. It can be moved around, freed, reused etc. at
1290	struct my_io *w = (struct my_io *)w_;	1406	will - as long as you either keep the memory contents intact, or call
1291	...	1407	C<ev_TYPE_init> again.
1292	}
1293		1408
1294	More interesting and less C-conformant ways of casting your callback type	1409	=item started/running/active
1295	instead have been omitted.
1296		1410
1297	Another common scenario is to use some data structure with multiple	1411	Once a watcher has been started with a call to C<ev_TYPE_start> it becomes
1298	embedded watchers:	1412	property of the event loop, and is actively waiting for events. While in
		1413	this state it cannot be accessed (except in a few documented ways), moved,
		1414	freed or anything else - the only legal thing is to keep a pointer to it,
		1415	and call libev functions on it that are documented to work on active watchers.
1299		1416
1300	struct my_biggy	1417	=item pending
1301	{
1302	int some_data;
1303	ev_timer t1;
1304	ev_timer t2;
1305	}
1306		1418
1307	In this case getting the pointer to C<my_biggy> is a bit more	1419	If a watcher is active and libev determines that an event it is interested
1308	complicated: Either you store the address of your C<my_biggy> struct	1420	in has occurred (such as a timer expiring), it will become pending. It will
1309	in the C<data> member of the watcher (for woozies), or you need to use	1421	stay in this pending state until either it is stopped or its callback is
1310	some pointer arithmetic using C<offsetof> inside your watchers (for real	1422	about to be invoked, so it is not normally pending inside the watcher
1311	programmers):	1423	callback.
1312		1424
1313	#include <stddef.h>	1425	The watcher might or might not be active while it is pending (for example,
		1426	an expired non-repeating timer can be pending but no longer active). If it
		1427	is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>),
		1428	but it is still property of the event loop at this time, so cannot be
		1429	moved, freed or reused. And if it is active the rules described in the
		1430	previous item still apply.
1314		1431
1315	static void	1432	It is also possible to feed an event on a watcher that is not active (e.g.
1316	t1_cb (EV_P_ ev_timer *w, int revents)	1433	via C<ev_feed_event>), in which case it becomes pending without being
1317	{	1434	active.
1318	struct my_biggy big = (struct my_biggy *)
1319	(((char *)w) - offsetof (struct my_biggy, t1));
1320	}
1321		1435
1322	static void	1436	=item stopped
1323	t2_cb (EV_P_ ev_timer *w, int revents)	1437
1324	{	1438	A watcher can be stopped implicitly by libev (in which case it might still
1325	struct my_biggy big = (struct my_biggy *)	1439	be pending), or explicitly by calling its C<ev_TYPE_stop> function. The
1326	(((char *)w) - offsetof (struct my_biggy, t2));	1440	latter will clear any pending state the watcher might be in, regardless
1327	}	1441	of whether it was active or not, so stopping a watcher explicitly before
		1442	freeing it is often a good idea.
		1443
		1444	While stopped (and not pending) the watcher is essentially in the
		1445	initialised state, that is, it can be reused, moved, modified in any way
		1446	you wish (but when you trash the memory block, you need to C<ev_TYPE_init>
		1447	it again).
		1448
		1449	=back
1328		1450
1329	=head2 WATCHER PRIORITY MODELS	1451	=head2 WATCHER PRIORITY MODELS
1330		1452
1331	Many event loops support I<watcher priorities>, which are usually small	1453	Many event loops support I<watcher priorities>, which are usually small
1332	integers that influence the ordering of event callback invocation	1454	integers that influence the ordering of event callback invocation
…		…
1375		1497
1376	For example, to emulate how many other event libraries handle priorities,	1498	For example, to emulate how many other event libraries handle priorities,
1377	you can associate an C<ev_idle> watcher to each such watcher, and in	1499	you can associate an C<ev_idle> watcher to each such watcher, and in
1378	the normal watcher callback, you just start the idle watcher. The real	1500	the normal watcher callback, you just start the idle watcher. The real
1379	processing is done in the idle watcher callback. This causes libev to	1501	processing is done in the idle watcher callback. This causes libev to
1380	continously poll and process kernel event data for the watcher, but when	1502	continuously poll and process kernel event data for the watcher, but when
1381	the lock-out case is known to be rare (which in turn is rare :), this is	1503	the lock-out case is known to be rare (which in turn is rare :), this is
1382	workable.	1504	workable.
1383		1505
1384	Usually, however, the lock-out model implemented that way will perform	1506	Usually, however, the lock-out model implemented that way will perform
1385	miserably under the type of load it was designed to handle. In that case,	1507	miserably under the type of load it was designed to handle. In that case,
…		…
1399	{	1521	{
1400	// stop the I/O watcher, we received the event, but	1522	// stop the I/O watcher, we received the event, but
1401	// are not yet ready to handle it.	1523	// are not yet ready to handle it.
1402	ev_io_stop (EV_A_ w);	1524	ev_io_stop (EV_A_ w);
1403		1525
1404	// start the idle watcher to ahndle the actual event.	1526	// start the idle watcher to handle the actual event.
1405	// it will not be executed as long as other watchers	1527	// it will not be executed as long as other watchers
1406	// with the default priority are receiving events.	1528	// with the default priority are receiving events.
1407	ev_idle_start (EV_A_ &idle);	1529	ev_idle_start (EV_A_ &idle);
1408	}	1530	}
1409		1531
…		…
1459	In general you can register as many read and/or write event watchers per	1581	In general you can register as many read and/or write event watchers per
1460	fd as you want (as long as you don't confuse yourself). Setting all file	1582	fd as you want (as long as you don't confuse yourself). Setting all file
1461	descriptors to non-blocking mode is also usually a good idea (but not	1583	descriptors to non-blocking mode is also usually a good idea (but not
1462	required if you know what you are doing).	1584	required if you know what you are doing).
1463		1585
1464	If you cannot use non-blocking mode, then force the use of a
1465	known-to-be-good backend (at the time of this writing, this includes only
1466	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file
1467	descriptors for which non-blocking operation makes no sense (such as
1468	files) - libev doesn't guarentee any specific behaviour in that case.
1469
1470	Another thing you have to watch out for is that it is quite easy to	1586	Another thing you have to watch out for is that it is quite easy to
1471	receive "spurious" readiness notifications, that is your callback might	1587	receive "spurious" readiness notifications, that is, your callback might
1472	be called with C<EV_READ> but a subsequent C<read>(2) will actually block	1588	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
1473	because there is no data. Not only are some backends known to create a	1589	because there is no data. It is very easy to get into this situation even
1474	lot of those (for example Solaris ports), it is very easy to get into	1590	with a relatively standard program structure. Thus it is best to always
1475	this situation even with a relatively standard program structure. Thus	1591	use non-blocking I/O: An extra C<read>(2) returning C<EAGAIN> is far
1476	it is best to always use non-blocking I/O: An extra C<read>(2) returning
1477	C<EAGAIN> is far preferable to a program hanging until some data arrives.	1592	preferable to a program hanging until some data arrives.
1478		1593
1479	If you cannot run the fd in non-blocking mode (for example you should	1594	If you cannot run the fd in non-blocking mode (for example you should
1480	not play around with an Xlib connection), then you have to separately	1595	not play around with an Xlib connection), then you have to separately
1481	re-test whether a file descriptor is really ready with a known-to-be good	1596	re-test whether a file descriptor is really ready with a known-to-be good
1482	interface such as poll (fortunately in our Xlib example, Xlib already	1597	interface such as poll (fortunately in the case of Xlib, it already does
1483	does this on its own, so its quite safe to use). Some people additionally	1598	this on its own, so its quite safe to use). Some people additionally
1484	use C<SIGALRM> and an interval timer, just to be sure you won't block	1599	use C<SIGALRM> and an interval timer, just to be sure you won't block
1485	indefinitely.	1600	indefinitely.
1486		1601
1487	But really, best use non-blocking mode.	1602	But really, best use non-blocking mode.
1488		1603
…		…
1516		1631
1517	There is no workaround possible except not registering events	1632	There is no workaround possible except not registering events
1518	for potentially C<dup ()>'ed file descriptors, or to resort to	1633	for potentially C<dup ()>'ed file descriptors, or to resort to
1519	C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>.	1634	C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>.
1520		1635
		1636	=head3 The special problem of files
		1637
		1638	Many people try to use C<select> (or libev) on file descriptors
		1639	representing files, and expect it to become ready when their program
		1640	doesn't block on disk accesses (which can take a long time on their own).
		1641
		1642	However, this cannot ever work in the "expected" way - you get a readiness
		1643	notification as soon as the kernel knows whether and how much data is
		1644	there, and in the case of open files, that's always the case, so you
		1645	always get a readiness notification instantly, and your read (or possibly
		1646	write) will still block on the disk I/O.
		1647
		1648	Another way to view it is that in the case of sockets, pipes, character
		1649	devices and so on, there is another party (the sender) that delivers data
		1650	on its own, but in the case of files, there is no such thing: the disk
		1651	will not send data on its own, simply because it doesn't know what you
		1652	wish to read - you would first have to request some data.
		1653
		1654	Since files are typically not-so-well supported by advanced notification
		1655	mechanism, libev tries hard to emulate POSIX behaviour with respect
		1656	to files, even though you should not use it. The reason for this is
		1657	convenience: sometimes you want to watch STDIN or STDOUT, which is
		1658	usually a tty, often a pipe, but also sometimes files or special devices
		1659	(for example, C<epoll> on Linux works with F</dev/random> but not with
		1660	F</dev/urandom>), and even though the file might better be served with
		1661	asynchronous I/O instead of with non-blocking I/O, it is still useful when
		1662	it "just works" instead of freezing.
		1663
		1664	So avoid file descriptors pointing to files when you know it (e.g. use
		1665	libeio), but use them when it is convenient, e.g. for STDIN/STDOUT, or
		1666	when you rarely read from a file instead of from a socket, and want to
		1667	reuse the same code path.
		1668
1521	=head3 The special problem of fork	1669	=head3 The special problem of fork
1522		1670
1523	Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit	1671	Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit
1524	useless behaviour. Libev fully supports fork, but needs to be told about	1672	useless behaviour. Libev fully supports fork, but needs to be told about
1525	it in the child.	1673	it in the child if you want to continue to use it in the child.
1526		1674
1527	To support fork in your programs, you either have to call	1675	To support fork in your child processes, you have to call C<ev_loop_fork
1528	C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child,	1676	()> after a fork in the child, enable C<EVFLAG_FORKCHECK>, or resort to
1529	enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or	1677	C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>.
1530	C<EVBACKEND_POLL>.
1531		1678
1532	=head3 The special problem of SIGPIPE	1679	=head3 The special problem of SIGPIPE
1533		1680
1534	While not really specific to libev, it is easy to forget about C<SIGPIPE>:	1681	While not really specific to libev, it is easy to forget about C<SIGPIPE>:
1535	when writing to a pipe whose other end has been closed, your program gets	1682	when writing to a pipe whose other end has been closed, your program gets
…		…
1541	somewhere, as that would have given you a big clue).	1688	somewhere, as that would have given you a big clue).
1542		1689
1543	=head3 The special problem of accept()ing when you can't	1690	=head3 The special problem of accept()ing when you can't
1544		1691
1545	Many implementations of the POSIX C<accept> function (for example,	1692	Many implementations of the POSIX C<accept> function (for example,
1546	found in port-2004 Linux) have the peculiar behaviour of not removing a	1693	found in post-2004 Linux) have the peculiar behaviour of not removing a
1547	connection from the pending queue in all error cases.	1694	connection from the pending queue in all error cases.
1548		1695
1549	For example, larger servers often run out of file descriptors (because	1696	For example, larger servers often run out of file descriptors (because
1550	of resource limits), causing C<accept> to fail with C<ENFILE> but not	1697	of resource limits), causing C<accept> to fail with C<ENFILE> but not
1551	rejecting the connection, leading to libev signalling readiness on	1698	rejecting the connection, leading to libev signalling readiness on
…		…
1617	...	1764	...
1618	struct ev_loop *loop = ev_default_init (0);	1765	struct ev_loop *loop = ev_default_init (0);
1619	ev_io stdin_readable;	1766	ev_io stdin_readable;
1620	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1767	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1621	ev_io_start (loop, &stdin_readable);	1768	ev_io_start (loop, &stdin_readable);
1622	ev_loop (loop, 0);	1769	ev_run (loop, 0);
1623		1770
1624		1771
1625	=head2 C<ev_timer> - relative and optionally repeating timeouts	1772	=head2 C<ev_timer> - relative and optionally repeating timeouts
1626		1773
1627	Timer watchers are simple relative timers that generate an event after a	1774	Timer watchers are simple relative timers that generate an event after a
…		…
1633	detecting time jumps is hard, and some inaccuracies are unavoidable (the	1780	detecting time jumps is hard, and some inaccuracies are unavoidable (the
1634	monotonic clock option helps a lot here).	1781	monotonic clock option helps a lot here).
1635		1782
1636	The callback is guaranteed to be invoked only I<after> its timeout has	1783	The callback is guaranteed to be invoked only I<after> its timeout has
1637	passed (not I<at>, so on systems with very low-resolution clocks this	1784	passed (not I<at>, so on systems with very low-resolution clocks this
1638	might introduce a small delay). If multiple timers become ready during the	1785	might introduce a small delay, see "the special problem of being too
		1786	early", below). If multiple timers become ready during the same loop
1639	same loop iteration then the ones with earlier time-out values are invoked	1787	iteration then the ones with earlier time-out values are invoked before
1640	before ones of the same priority with later time-out values (but this is	1788	ones of the same priority with later time-out values (but this is no
1641	no longer true when a callback calls C<ev_loop> recursively).	1789	longer true when a callback calls C<ev_run> recursively).
1642		1790
1643	=head3 Be smart about timeouts	1791	=head3 Be smart about timeouts
1644		1792
1645	Many real-world problems involve some kind of timeout, usually for error	1793	Many real-world problems involve some kind of timeout, usually for error
1646	recovery. A typical example is an HTTP request - if the other side hangs,	1794	recovery. A typical example is an HTTP request - if the other side hangs,
…		…
1721		1869
1722	In this case, it would be more efficient to leave the C<ev_timer> alone,	1870	In this case, it would be more efficient to leave the C<ev_timer> alone,
1723	but remember the time of last activity, and check for a real timeout only	1871	but remember the time of last activity, and check for a real timeout only
1724	within the callback:	1872	within the callback:
1725		1873
		1874	ev_tstamp timeout = 60.;
1726	ev_tstamp last_activity; // time of last activity	1875	ev_tstamp last_activity; // time of last activity
		1876	ev_timer timer;
1727		1877
1728	static void	1878	static void
1729	callback (EV_P_ ev_timer *w, int revents)	1879	callback (EV_P_ ev_timer *w, int revents)
1730	{	1880	{
1731	ev_tstamp now = ev_now (EV_A);	1881	// calculate when the timeout would happen
1732	ev_tstamp timeout = last_activity + 60.;	1882	ev_tstamp after = last_activity - ev_now (EV_A) + timeout;
1733		1883
1734	// if last_activity + 60. is older than now, we did time out	1884	// if negative, it means we the timeout already occurred
1735	if (timeout < now)	1885	if (after < 0.)
1736	{	1886	{
1737	// timeout occured, take action	1887	// timeout occurred, take action
1738	}	1888	}
1739	else	1889	else
1740	{	1890	{
1741	// callback was invoked, but there was some activity, re-arm	1891	// callback was invoked, but there was some recent
1742	// the watcher to fire in last_activity + 60, which is	1892	// activity. simply restart the timer to time out
1743	// guaranteed to be in the future, so "again" is positive:	1893	// after "after" seconds, which is the earliest time
1744	w->repeat = timeout - now;	1894	// the timeout can occur.
		1895	ev_timer_set (w, after, 0.);
1745	ev_timer_again (EV_A_ w);	1896	ev_timer_start (EV_A_ w);
1746	}	1897	}
1747	}	1898	}
1748		1899
1749	To summarise the callback: first calculate the real timeout (defined	1900	To summarise the callback: first calculate in how many seconds the
1750	as "60 seconds after the last activity"), then check if that time has	1901	timeout will occur (by calculating the absolute time when it would occur,
1751	been reached, which means something I<did>, in fact, time out. Otherwise	1902	C<last_activity + timeout>, and subtracting the current time, C<ev_now
1752	the callback was invoked too early (C<timeout> is in the future), so	1903	(EV_A)> from that).
1753	re-schedule the timer to fire at that future time, to see if maybe we have
1754	a timeout then.
1755		1904
1756	Note how C<ev_timer_again> is used, taking advantage of the	1905	If this value is negative, then we are already past the timeout, i.e. we
1757	C<ev_timer_again> optimisation when the timer is already running.	1906	timed out, and need to do whatever is needed in this case.
		1907
		1908	Otherwise, we now the earliest time at which the timeout would trigger,
		1909	and simply start the timer with this timeout value.
		1910
		1911	In other words, each time the callback is invoked it will check whether
		1912	the timeout occurred. If not, it will simply reschedule itself to check
		1913	again at the earliest time it could time out. Rinse. Repeat.
1758		1914
1759	This scheme causes more callback invocations (about one every 60 seconds	1915	This scheme causes more callback invocations (about one every 60 seconds
1760	minus half the average time between activity), but virtually no calls to	1916	minus half the average time between activity), but virtually no calls to
1761	libev to change the timeout.	1917	libev to change the timeout.
1762		1918
1763	To start the timer, simply initialise the watcher and set C<last_activity>	1919	To start the machinery, simply initialise the watcher and set
1764	to the current time (meaning we just have some activity :), then call the	1920	C<last_activity> to the current time (meaning there was some activity just
1765	callback, which will "do the right thing" and start the timer:	1921	now), then call the callback, which will "do the right thing" and start
		1922	the timer:
1766		1923
		1924	last_activity = ev_now (EV_A);
1767	ev_init (timer, callback);	1925	ev_init (&timer, callback);
1768	last_activity = ev_now (loop);	1926	callback (EV_A_ &timer, 0);
1769	callback (loop, timer, EV_TIMEOUT);
1770		1927
1771	And when there is some activity, simply store the current time in	1928	When there is some activity, simply store the current time in
1772	C<last_activity>, no libev calls at all:	1929	C<last_activity>, no libev calls at all:
1773		1930
		1931	if (activity detected)
1774	last_actiivty = ev_now (loop);	1932	last_activity = ev_now (EV_A);
		1933
		1934	When your timeout value changes, then the timeout can be changed by simply
		1935	providing a new value, stopping the timer and calling the callback, which
		1936	will again do the right thing (for example, time out immediately :).
		1937
		1938	timeout = new_value;
		1939	ev_timer_stop (EV_A_ &timer);
		1940	callback (EV_A_ &timer, 0);
1775		1941
1776	This technique is slightly more complex, but in most cases where the	1942	This technique is slightly more complex, but in most cases where the
1777	time-out is unlikely to be triggered, much more efficient.	1943	time-out is unlikely to be triggered, much more efficient.
1778
1779	Changing the timeout is trivial as well (if it isn't hard-coded in the
1780	callback :) - just change the timeout and invoke the callback, which will
1781	fix things for you.
1782		1944
1783	=item 4. Wee, just use a double-linked list for your timeouts.	1945	=item 4. Wee, just use a double-linked list for your timeouts.
1784		1946
1785	If there is not one request, but many thousands (millions...), all	1947	If there is not one request, but many thousands (millions...), all
1786	employing some kind of timeout with the same timeout value, then one can	1948	employing some kind of timeout with the same timeout value, then one can
…		…
1813	Method #1 is almost always a bad idea, and buys you nothing. Method #4 is	1975	Method #1 is almost always a bad idea, and buys you nothing. Method #4 is
1814	rather complicated, but extremely efficient, something that really pays	1976	rather complicated, but extremely efficient, something that really pays
1815	off after the first million or so of active timers, i.e. it's usually	1977	off after the first million or so of active timers, i.e. it's usually
1816	overkill :)	1978	overkill :)
1817		1979
		1980	=head3 The special problem of being too early
		1981
		1982	If you ask a timer to call your callback after three seconds, then
		1983	you expect it to be invoked after three seconds - but of course, this
		1984	cannot be guaranteed to infinite precision. Less obviously, it cannot be
		1985	guaranteed to any precision by libev - imagine somebody suspending the
		1986	process with a STOP signal for a few hours for example.
		1987
		1988	So, libev tries to invoke your callback as soon as possible I<after> the
		1989	delay has occurred, but cannot guarantee this.
		1990
		1991	A less obvious failure mode is calling your callback too early: many event
		1992	loops compare timestamps with a "elapsed delay >= requested delay", but
		1993	this can cause your callback to be invoked much earlier than you would
		1994	expect.
		1995
		1996	To see why, imagine a system with a clock that only offers full second
		1997	resolution (think windows if you can't come up with a broken enough OS
		1998	yourself). If you schedule a one-second timer at the time 500.9, then the
		1999	event loop will schedule your timeout to elapse at a system time of 500
		2000	(500.9 truncated to the resolution) + 1, or 501.
		2001
		2002	If an event library looks at the timeout 0.1s later, it will see "501 >=
		2003	501" and invoke the callback 0.1s after it was started, even though a
		2004	one-second delay was requested - this is being "too early", despite best
		2005	intentions.
		2006
		2007	This is the reason why libev will never invoke the callback if the elapsed
		2008	delay equals the requested delay, but only when the elapsed delay is
		2009	larger than the requested delay. In the example above, libev would only invoke
		2010	the callback at system time 502, or 1.1s after the timer was started.
		2011
		2012	So, while libev cannot guarantee that your callback will be invoked
		2013	exactly when requested, it I<can> and I<does> guarantee that the requested
		2014	delay has actually elapsed, or in other words, it always errs on the "too
		2015	late" side of things.
		2016
1818	=head3 The special problem of time updates	2017	=head3 The special problem of time updates
1819		2018
1820	Establishing the current time is a costly operation (it usually takes at	2019	Establishing the current time is a costly operation (it usually takes
1821	least two system calls): EV therefore updates its idea of the current	2020	at least one system call): EV therefore updates its idea of the current
1822	time only before and after C<ev_loop> collects new events, which causes a	2021	time only before and after C<ev_run> collects new events, which causes a
1823	growing difference between C<ev_now ()> and C<ev_time ()> when handling	2022	growing difference between C<ev_now ()> and C<ev_time ()> when handling
1824	lots of events in one iteration.	2023	lots of events in one iteration.
1825		2024
1826	The relative timeouts are calculated relative to the C<ev_now ()>	2025	The relative timeouts are calculated relative to the C<ev_now ()>
1827	time. This is usually the right thing as this timestamp refers to the time	2026	time. This is usually the right thing as this timestamp refers to the time
…		…
1832	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);	2031	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);
1833		2032
1834	If the event loop is suspended for a long time, you can also force an	2033	If the event loop is suspended for a long time, you can also force an
1835	update of the time returned by C<ev_now ()> by calling C<ev_now_update	2034	update of the time returned by C<ev_now ()> by calling C<ev_now_update
1836	()>.	2035	()>.
		2036
		2037	=head3 The special problem of unsynchronised clocks
		2038
		2039	Modern systems have a variety of clocks - libev itself uses the normal
		2040	"wall clock" clock and, if available, the monotonic clock (to avoid time
		2041	jumps).
		2042
		2043	Neither of these clocks is synchronised with each other or any other clock
		2044	on the system, so C<ev_time ()> might return a considerably different time
		2045	than C<gettimeofday ()> or C<time ()>. On a GNU/Linux system, for example,
		2046	a call to C<gettimeofday> might return a second count that is one higher
		2047	than a directly following call to C<time>.
		2048
		2049	The moral of this is to only compare libev-related timestamps with
		2050	C<ev_time ()> and C<ev_now ()>, at least if you want better precision than
		2051	a second or so.
		2052
		2053	One more problem arises due to this lack of synchronisation: if libev uses
		2054	the system monotonic clock and you compare timestamps from C<ev_time>
		2055	or C<ev_now> from when you started your timer and when your callback is
		2056	invoked, you will find that sometimes the callback is a bit "early".
		2057
		2058	This is because C<ev_timer>s work in real time, not wall clock time, so
		2059	libev makes sure your callback is not invoked before the delay happened,
		2060	I<measured according to the real time>, not the system clock.
		2061
		2062	If your timeouts are based on a physical timescale (e.g. "time out this
		2063	connection after 100 seconds") then this shouldn't bother you as it is
		2064	exactly the right behaviour.
		2065
		2066	If you want to compare wall clock/system timestamps to your timers, then
		2067	you need to use C<ev_periodic>s, as these are based on the wall clock
		2068	time, where your comparisons will always generate correct results.
1837		2069
1838	=head3 The special problems of suspended animation	2070	=head3 The special problems of suspended animation
1839		2071
1840	When you leave the server world it is quite customary to hit machines that	2072	When you leave the server world it is quite customary to hit machines that
1841	can suspend/hibernate - what happens to the clocks during such a suspend?	2073	can suspend/hibernate - what happens to the clocks during such a suspend?
…		…
1885	keep up with the timer (because it takes longer than those 10 seconds to	2117	keep up with the timer (because it takes longer than those 10 seconds to
1886	do stuff) the timer will not fire more than once per event loop iteration.	2118	do stuff) the timer will not fire more than once per event loop iteration.
1887		2119
1888	=item ev_timer_again (loop, ev_timer *)	2120	=item ev_timer_again (loop, ev_timer *)
1889		2121
1890	This will act as if the timer timed out and restart it again if it is	2122	This will act as if the timer timed out, and restarts it again if it is
1891	repeating. The exact semantics are:	2123	repeating. It basically works like calling C<ev_timer_stop>, updating the
		2124	timeout to the C<repeat> value and calling C<ev_timer_start>.
1892		2125
		2126	The exact semantics are as in the following rules, all of which will be
		2127	applied to the watcher:
		2128
		2129	=over 4
		2130
1893	If the timer is pending, its pending status is cleared.	2131	=item If the timer is pending, the pending status is always cleared.
1894		2132
1895	If the timer is started but non-repeating, stop it (as if it timed out).	2133	=item If the timer is started but non-repeating, stop it (as if it timed
		2134	out, without invoking it).
1896		2135
1897	If the timer is repeating, either start it if necessary (with the	2136	=item If the timer is repeating, make the C<repeat> value the new timeout
1898	C<repeat> value), or reset the running timer to the C<repeat> value.	2137	and start the timer, if necessary.
1899		2138
		2139	=back
		2140
1900	This sounds a bit complicated, see L<Be smart about timeouts>, above, for a	2141	This sounds a bit complicated, see L</Be smart about timeouts>, above, for a
1901	usage example.	2142	usage example.
1902		2143
1903	=item ev_tstamp ev_timer_remaining (loop, ev_timer *)	2144	=item ev_tstamp ev_timer_remaining (loop, ev_timer *)
1904		2145
1905	Returns the remaining time until a timer fires. If the timer is active,	2146	Returns the remaining time until a timer fires. If the timer is active,
…		…
1944	}	2185	}
1945		2186
1946	ev_timer mytimer;	2187	ev_timer mytimer;
1947	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	2188	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1948	ev_timer_again (&mytimer); /* start timer */	2189	ev_timer_again (&mytimer); /* start timer */
1949	ev_loop (loop, 0);	2190	ev_run (loop, 0);
1950		2191
1951	// and in some piece of code that gets executed on any "activity":	2192	// and in some piece of code that gets executed on any "activity":
1952	// reset the timeout to start ticking again at 10 seconds	2193	// reset the timeout to start ticking again at 10 seconds
1953	ev_timer_again (&mytimer);	2194	ev_timer_again (&mytimer);
1954		2195
…		…
1980		2221
1981	As with timers, the callback is guaranteed to be invoked only when the	2222	As with timers, the callback is guaranteed to be invoked only when the
1982	point in time where it is supposed to trigger has passed. If multiple	2223	point in time where it is supposed to trigger has passed. If multiple
1983	timers become ready during the same loop iteration then the ones with	2224	timers become ready during the same loop iteration then the ones with
1984	earlier time-out values are invoked before ones with later time-out values	2225	earlier time-out values are invoked before ones with later time-out values
1985	(but this is no longer true when a callback calls C<ev_loop> recursively).	2226	(but this is no longer true when a callback calls C<ev_run> recursively).
1986		2227
1987	=head3 Watcher-Specific Functions and Data Members	2228	=head3 Watcher-Specific Functions and Data Members
1988		2229
1989	=over 4	2230	=over 4
1990		2231
…		…
2025		2266
2026	Another way to think about it (for the mathematically inclined) is that	2267	Another way to think about it (for the mathematically inclined) is that
2027	C<ev_periodic> will try to run the callback in this mode at the next possible	2268	C<ev_periodic> will try to run the callback in this mode at the next possible
2028	time where C<time = offset (mod interval)>, regardless of any time jumps.	2269	time where C<time = offset (mod interval)>, regardless of any time jumps.
2029		2270
2030	For numerical stability it is preferable that the C<offset> value is near	2271	The C<interval> I<MUST> be positive, and for numerical stability, the
2031	C<ev_now ()> (the current time), but there is no range requirement for	2272	interval value should be higher than C<1/8192> (which is around 100
2032	this value, and in fact is often specified as zero.	2273	microseconds) and C<offset> should be higher than C<0> and should have
		2274	at most a similar magnitude as the current time (say, within a factor of
		2275	ten). Typical values for offset are, in fact, C<0> or something between
		2276	C<0> and C<interval>, which is also the recommended range.
2033		2277
2034	Note also that there is an upper limit to how often a timer can fire (CPU	2278	Note also that there is an upper limit to how often a timer can fire (CPU
2035	speed for example), so if C<interval> is very small then timing stability	2279	speed for example), so if C<interval> is very small then timing stability
2036	will of course deteriorate. Libev itself tries to be exact to be about one	2280	will of course deteriorate. Libev itself tries to be exact to be about one
2037	millisecond (if the OS supports it and the machine is fast enough).	2281	millisecond (if the OS supports it and the machine is fast enough).
…		…
2118	Example: Call a callback every hour, or, more precisely, whenever the	2362	Example: Call a callback every hour, or, more precisely, whenever the
2119	system time is divisible by 3600. The callback invocation times have	2363	system time is divisible by 3600. The callback invocation times have
2120	potentially a lot of jitter, but good long-term stability.	2364	potentially a lot of jitter, but good long-term stability.
2121		2365
2122	static void	2366	static void
2123	clock_cb (struct ev_loop *loop, ev_io *w, int revents)	2367	clock_cb (struct ev_loop *loop, ev_periodic *w, int revents)
2124	{	2368	{
2125	... its now a full hour (UTC, or TAI or whatever your clock follows)	2369	... its now a full hour (UTC, or TAI or whatever your clock follows)
2126	}	2370	}
2127		2371
2128	ev_periodic hourly_tick;	2372	ev_periodic hourly_tick;
…		…
2151		2395
2152	=head2 C<ev_signal> - signal me when a signal gets signalled!	2396	=head2 C<ev_signal> - signal me when a signal gets signalled!
2153		2397
2154	Signal watchers will trigger an event when the process receives a specific	2398	Signal watchers will trigger an event when the process receives a specific
2155	signal one or more times. Even though signals are very asynchronous, libev	2399	signal one or more times. Even though signals are very asynchronous, libev
2156	will try it's best to deliver signals synchronously, i.e. as part of the	2400	will try its best to deliver signals synchronously, i.e. as part of the
2157	normal event processing, like any other event.	2401	normal event processing, like any other event.
2158		2402
2159	If you want signals to be delivered truly asynchronously, just use	2403	If you want signals to be delivered truly asynchronously, just use
2160	C<sigaction> as you would do without libev and forget about sharing	2404	C<sigaction> as you would do without libev and forget about sharing
2161	the signal. You can even use C<ev_async> from a signal handler to	2405	the signal. You can even use C<ev_async> from a signal handler to
…		…
2180	=head3 The special problem of inheritance over fork/execve/pthread_create	2424	=head3 The special problem of inheritance over fork/execve/pthread_create
2181		2425
2182	Both the signal mask (C<sigprocmask>) and the signal disposition	2426	Both the signal mask (C<sigprocmask>) and the signal disposition
2183	(C<sigaction>) are unspecified after starting a signal watcher (and after	2427	(C<sigaction>) are unspecified after starting a signal watcher (and after
2184	stopping it again), that is, libev might or might not block the signal,	2428	stopping it again), that is, libev might or might not block the signal,
2185	and might or might not set or restore the installed signal handler.	2429	and might or might not set or restore the installed signal handler (but
		2430	see C<EVFLAG_NOSIGMASK>).
2186		2431
2187	While this does not matter for the signal disposition (libev never	2432	While this does not matter for the signal disposition (libev never
2188	sets signals to C<SIG_IGN>, so handlers will be reset to C<SIG_DFL> on	2433	sets signals to C<SIG_IGN>, so handlers will be reset to C<SIG_DFL> on
2189	C<execve>), this matters for the signal mask: many programs do not expect	2434	C<execve>), this matters for the signal mask: many programs do not expect
2190	certain signals to be blocked.	2435	certain signals to be blocked.
…		…
2204		2449
2205	So I can't stress this enough: I<If you do not reset your signal mask when	2450	So I can't stress this enough: I<If you do not reset your signal mask when
2206	you expect it to be empty, you have a race condition in your code>. This	2451	you expect it to be empty, you have a race condition in your code>. This
2207	is not a libev-specific thing, this is true for most event libraries.	2452	is not a libev-specific thing, this is true for most event libraries.
2208		2453
		2454	=head3 The special problem of threads signal handling
		2455
		2456	POSIX threads has problematic signal handling semantics, specifically,
		2457	a lot of functionality (sigfd, sigwait etc.) only really works if all
		2458	threads in a process block signals, which is hard to achieve.
		2459
		2460	When you want to use sigwait (or mix libev signal handling with your own
		2461	for the same signals), you can tackle this problem by globally blocking
		2462	all signals before creating any threads (or creating them with a fully set
		2463	sigprocmask) and also specifying the C<EVFLAG_NOSIGMASK> when creating
		2464	loops. Then designate one thread as "signal receiver thread" which handles
		2465	these signals. You can pass on any signals that libev might be interested
		2466	in by calling C<ev_feed_signal>.
		2467
2209	=head3 Watcher-Specific Functions and Data Members	2468	=head3 Watcher-Specific Functions and Data Members
2210		2469
2211	=over 4	2470	=over 4
2212		2471
2213	=item ev_signal_init (ev_signal *, callback, int signum)	2472	=item ev_signal_init (ev_signal *, callback, int signum)
…		…
2228	Example: Try to exit cleanly on SIGINT.	2487	Example: Try to exit cleanly on SIGINT.
2229		2488
2230	static void	2489	static void
2231	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)	2490	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)
2232	{	2491	{
2233	ev_unloop (loop, EVUNLOOP_ALL);	2492	ev_break (loop, EVBREAK_ALL);
2234	}	2493	}
2235		2494
2236	ev_signal signal_watcher;	2495	ev_signal signal_watcher;
2237	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	2496	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
2238	ev_signal_start (loop, &signal_watcher);	2497	ev_signal_start (loop, &signal_watcher);
…		…
2588	Apart from keeping your process non-blocking (which is a useful	2847	Apart from keeping your process non-blocking (which is a useful
2589	effect on its own sometimes), idle watchers are a good place to do	2848	effect on its own sometimes), idle watchers are a good place to do
2590	"pseudo-background processing", or delay processing stuff to after the	2849	"pseudo-background processing", or delay processing stuff to after the
2591	event loop has handled all outstanding events.	2850	event loop has handled all outstanding events.
2592		2851
		2852	=head3 Abusing an C<ev_idle> watcher for its side-effect
		2853
		2854	As long as there is at least one active idle watcher, libev will never
		2855	sleep unnecessarily. Or in other words, it will loop as fast as possible.
		2856	For this to work, the idle watcher doesn't need to be invoked at all - the
		2857	lowest priority will do.
		2858
		2859	This mode of operation can be useful together with an C<ev_check> watcher,
		2860	to do something on each event loop iteration - for example to balance load
		2861	between different connections.
		2862
		2863	See L</Abusing an ev_check watcher for its side-effect> for a longer
		2864	example.
		2865
2593	=head3 Watcher-Specific Functions and Data Members	2866	=head3 Watcher-Specific Functions and Data Members
2594		2867
2595	=over 4	2868	=over 4
2596		2869
2597	=item ev_idle_init (ev_idle *, callback)	2870	=item ev_idle_init (ev_idle *, callback)
…		…
2608	callback, free it. Also, use no error checking, as usual.	2881	callback, free it. Also, use no error checking, as usual.
2609		2882
2610	static void	2883	static void
2611	idle_cb (struct ev_loop *loop, ev_idle *w, int revents)	2884	idle_cb (struct ev_loop *loop, ev_idle *w, int revents)
2612	{	2885	{
		2886	// stop the watcher
		2887	ev_idle_stop (loop, w);
		2888
		2889	// now we can free it
2613	free (w);	2890	free (w);
		2891
2614	// now do something you wanted to do when the program has	2892	// now do something you wanted to do when the program has
2615	// no longer anything immediate to do.	2893	// no longer anything immediate to do.
2616	}	2894	}
2617		2895
2618	ev_idle *idle_watcher = malloc (sizeof (ev_idle));	2896	ev_idle *idle_watcher = malloc (sizeof (ev_idle));
…		…
2620	ev_idle_start (loop, idle_watcher);	2898	ev_idle_start (loop, idle_watcher);
2621		2899
2622		2900
2623	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!	2901	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!
2624		2902
2625	Prepare and check watchers are usually (but not always) used in pairs:	2903	Prepare and check watchers are often (but not always) used in pairs:
2626	prepare watchers get invoked before the process blocks and check watchers	2904	prepare watchers get invoked before the process blocks and check watchers
2627	afterwards.	2905	afterwards.
2628		2906
2629	You I<must not> call C<ev_loop> or similar functions that enter	2907	You I<must not> call C<ev_run> or similar functions that enter
2630	the current event loop from either C<ev_prepare> or C<ev_check>	2908	the current event loop from either C<ev_prepare> or C<ev_check>
2631	watchers. Other loops than the current one are fine, however. The	2909	watchers. Other loops than the current one are fine, however. The
2632	rationale behind this is that you do not need to check for recursion in	2910	rationale behind this is that you do not need to check for recursion in
2633	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,	2911	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,
2634	C<ev_check> so if you have one watcher of each kind they will always be	2912	C<ev_check> so if you have one watcher of each kind they will always be
…		…
2658	with priority higher than or equal to the event loop and one coroutine	2936	with priority higher than or equal to the event loop and one coroutine
2659	of lower priority, but only once, using idle watchers to keep the event	2937	of lower priority, but only once, using idle watchers to keep the event
2660	loop from blocking if lower-priority coroutines are active, thus mapping	2938	loop from blocking if lower-priority coroutines are active, thus mapping
2661	low-priority coroutines to idle/background tasks).	2939	low-priority coroutines to idle/background tasks).
2662		2940
2663	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)	2941	When used for this purpose, it is recommended to give C<ev_check> watchers
2664	priority, to ensure that they are being run before any other watchers	2942	highest (C<EV_MAXPRI>) priority, to ensure that they are being run before
2665	after the poll (this doesn't matter for C<ev_prepare> watchers).	2943	any other watchers after the poll (this doesn't matter for C<ev_prepare>
		2944	watchers).
2666		2945
2667	Also, C<ev_check> watchers (and C<ev_prepare> watchers, too) should not	2946	Also, C<ev_check> watchers (and C<ev_prepare> watchers, too) should not
2668	activate ("feed") events into libev. While libev fully supports this, they	2947	activate ("feed") events into libev. While libev fully supports this, they
2669	might get executed before other C<ev_check> watchers did their job. As	2948	might get executed before other C<ev_check> watchers did their job. As
2670	C<ev_check> watchers are often used to embed other (non-libev) event	2949	C<ev_check> watchers are often used to embed other (non-libev) event
2671	loops those other event loops might be in an unusable state until their	2950	loops those other event loops might be in an unusable state until their
2672	C<ev_check> watcher ran (always remind yourself to coexist peacefully with	2951	C<ev_check> watcher ran (always remind yourself to coexist peacefully with
2673	others).	2952	others).
		2953
		2954	=head3 Abusing an C<ev_check> watcher for its side-effect
		2955
		2956	C<ev_check> (and less often also C<ev_prepare>) watchers can also be
		2957	useful because they are called once per event loop iteration. For
		2958	example, if you want to handle a large number of connections fairly, you
		2959	normally only do a bit of work for each active connection, and if there
		2960	is more work to do, you wait for the next event loop iteration, so other
		2961	connections have a chance of making progress.
		2962
		2963	Using an C<ev_check> watcher is almost enough: it will be called on the
		2964	next event loop iteration. However, that isn't as soon as possible -
		2965	without external events, your C<ev_check> watcher will not be invoked.
		2966
		2967
		2968	This is where C<ev_idle> watchers come in handy - all you need is a
		2969	single global idle watcher that is active as long as you have one active
		2970	C<ev_check> watcher. The C<ev_idle> watcher makes sure the event loop
		2971	will not sleep, and the C<ev_check> watcher makes sure a callback gets
		2972	invoked. Neither watcher alone can do that.
2674		2973
2675	=head3 Watcher-Specific Functions and Data Members	2974	=head3 Watcher-Specific Functions and Data Members
2676		2975
2677	=over 4	2976	=over 4
2678		2977
…		…
2802		3101
2803	if (timeout >= 0)	3102	if (timeout >= 0)
2804	// create/start timer	3103	// create/start timer
2805		3104
2806	// poll	3105	// poll
2807	ev_loop (EV_A_ 0);	3106	ev_run (EV_A_ 0);
2808		3107
2809	// stop timer again	3108	// stop timer again
2810	if (timeout >= 0)	3109	if (timeout >= 0)
2811	ev_timer_stop (EV_A_ &to);	3110	ev_timer_stop (EV_A_ &to);
2812		3111
…		…
2890	if you do not want that, you need to temporarily stop the embed watcher).	3189	if you do not want that, you need to temporarily stop the embed watcher).
2891		3190
2892	=item ev_embed_sweep (loop, ev_embed *)	3191	=item ev_embed_sweep (loop, ev_embed *)
2893		3192
2894	Make a single, non-blocking sweep over the embedded loop. This works	3193	Make a single, non-blocking sweep over the embedded loop. This works
2895	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	3194	similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most
2896	appropriate way for embedded loops.	3195	appropriate way for embedded loops.
2897		3196
2898	=item struct ev_loop *other [read-only]	3197	=item struct ev_loop *other [read-only]
2899		3198
2900	The embedded event loop.	3199	The embedded event loop.
…		…
2960	C<ev_default_fork> cheats and calls it in the wrong process, the fork	3259	C<ev_default_fork> cheats and calls it in the wrong process, the fork
2961	handlers will be invoked, too, of course.	3260	handlers will be invoked, too, of course.
2962		3261
2963	=head3 The special problem of life after fork - how is it possible?	3262	=head3 The special problem of life after fork - how is it possible?
2964		3263
2965	Most uses of C<fork()> consist of forking, then some simple calls to ste	3264	Most uses of C<fork()> consist of forking, then some simple calls to set
2966	up/change the process environment, followed by a call to C<exec()>. This	3265	up/change the process environment, followed by a call to C<exec()>. This
2967	sequence should be handled by libev without any problems.	3266	sequence should be handled by libev without any problems.
2968		3267
2969	This changes when the application actually wants to do event handling	3268	This changes when the application actually wants to do event handling
2970	in the child, or both parent in child, in effect "continuing" after the	3269	in the child, or both parent in child, in effect "continuing" after the
…		…
2986	disadvantage of having to use multiple event loops (which do not support	3285	disadvantage of having to use multiple event loops (which do not support
2987	signal watchers).	3286	signal watchers).
2988		3287
2989	When this is not possible, or you want to use the default loop for	3288	When this is not possible, or you want to use the default loop for
2990	other reasons, then in the process that wants to start "fresh", call	3289	other reasons, then in the process that wants to start "fresh", call
2991	C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying	3290	C<ev_loop_destroy (EV_DEFAULT)> followed by C<ev_default_loop (...)>.
2992	the default loop will "orphan" (not stop) all registered watchers, so you	3291	Destroying the default loop will "orphan" (not stop) all registered
2993	have to be careful not to execute code that modifies those watchers. Note	3292	watchers, so you have to be careful not to execute code that modifies
2994	also that in that case, you have to re-register any signal watchers.	3293	those watchers. Note also that in that case, you have to re-register any
		3294	signal watchers.
2995		3295
2996	=head3 Watcher-Specific Functions and Data Members	3296	=head3 Watcher-Specific Functions and Data Members
2997		3297
2998	=over 4	3298	=over 4
2999		3299
3000	=item ev_fork_init (ev_signal *, callback)	3300	=item ev_fork_init (ev_fork *, callback)
3001		3301
3002	Initialises and configures the fork watcher - it has no parameters of any	3302	Initialises and configures the fork watcher - it has no parameters of any
3003	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,	3303	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
3004	believe me.	3304	really.
3005		3305
3006	=back	3306	=back
3007		3307
3008		3308
		3309	=head2 C<ev_cleanup> - even the best things end
		3310
		3311	Cleanup watchers are called just before the event loop is being destroyed
		3312	by a call to C<ev_loop_destroy>.
		3313
		3314	While there is no guarantee that the event loop gets destroyed, cleanup
		3315	watchers provide a convenient method to install cleanup hooks for your
		3316	program, worker threads and so on - you just to make sure to destroy the
		3317	loop when you want them to be invoked.
		3318
		3319	Cleanup watchers are invoked in the same way as any other watcher. Unlike
		3320	all other watchers, they do not keep a reference to the event loop (which
		3321	makes a lot of sense if you think about it). Like all other watchers, you
		3322	can call libev functions in the callback, except C<ev_cleanup_start>.
		3323
		3324	=head3 Watcher-Specific Functions and Data Members
		3325
		3326	=over 4
		3327
		3328	=item ev_cleanup_init (ev_cleanup *, callback)
		3329
		3330	Initialises and configures the cleanup watcher - it has no parameters of
		3331	any kind. There is a C<ev_cleanup_set> macro, but using it is utterly
		3332	pointless, I assure you.
		3333
		3334	=back
		3335
		3336	Example: Register an atexit handler to destroy the default loop, so any
		3337	cleanup functions are called.
		3338
		3339	static void
		3340	program_exits (void)
		3341	{
		3342	ev_loop_destroy (EV_DEFAULT_UC);
		3343	}
		3344
		3345	...
		3346	atexit (program_exits);
		3347
		3348
3009	=head2 C<ev_async> - how to wake up another event loop	3349	=head2 C<ev_async> - how to wake up an event loop
3010		3350
3011	In general, you cannot use an C<ev_loop> from multiple threads or other	3351	In general, you cannot use an C<ev_loop> from multiple threads or other
3012	asynchronous sources such as signal handlers (as opposed to multiple event	3352	asynchronous sources such as signal handlers (as opposed to multiple event
3013	loops - those are of course safe to use in different threads).	3353	loops - those are of course safe to use in different threads).
3014		3354
3015	Sometimes, however, you need to wake up another event loop you do not	3355	Sometimes, however, you need to wake up an event loop you do not control,
3016	control, for example because it belongs to another thread. This is what	3356	for example because it belongs to another thread. This is what C<ev_async>
3017	C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you	3357	watchers do: as long as the C<ev_async> watcher is active, you can signal
3018	can signal it by calling C<ev_async_send>, which is thread- and signal	3358	it by calling C<ev_async_send>, which is thread- and signal safe.
3019	safe.
3020		3359
3021	This functionality is very similar to C<ev_signal> watchers, as signals,	3360	This functionality is very similar to C<ev_signal> watchers, as signals,
3022	too, are asynchronous in nature, and signals, too, will be compressed	3361	too, are asynchronous in nature, and signals, too, will be compressed
3023	(i.e. the number of callback invocations may be less than the number of	3362	(i.e. the number of callback invocations may be less than the number of
3024	C<ev_async_sent> calls).	3363	C<ev_async_send> calls). In fact, you could use signal watchers as a kind
3025		3364	of "global async watchers" by using a watcher on an otherwise unused
3026	Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not	3365	signal, and C<ev_feed_signal> to signal this watcher from another thread,
3027	just the default loop.	3366	even without knowing which loop owns the signal.
3028		3367
3029	=head3 Queueing	3368	=head3 Queueing
3030		3369
3031	C<ev_async> does not support queueing of data in any way. The reason	3370	C<ev_async> does not support queueing of data in any way. The reason
3032	is that the author does not know of a simple (or any) algorithm for a	3371	is that the author does not know of a simple (or any) algorithm for a
…		…
3124	trust me.	3463	trust me.
3125		3464
3126	=item ev_async_send (loop, ev_async *)	3465	=item ev_async_send (loop, ev_async *)
3127		3466
3128	Sends/signals/activates the given C<ev_async> watcher, that is, feeds	3467	Sends/signals/activates the given C<ev_async> watcher, that is, feeds
3129	an C<EV_ASYNC> event on the watcher into the event loop. Unlike	3468	an C<EV_ASYNC> event on the watcher into the event loop, and instantly
		3469	returns.
		3470
3130	C<ev_feed_event>, this call is safe to do from other threads, signal or	3471	Unlike C<ev_feed_event>, this call is safe to do from other threads,
3131	similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding	3472	signal or similar contexts (see the discussion of C<EV_ATOMIC_T> in the
3132	section below on what exactly this means).	3473	embedding section below on what exactly this means).
3133		3474
3134	Note that, as with other watchers in libev, multiple events might get	3475	Note that, as with other watchers in libev, multiple events might get
3135	compressed into a single callback invocation (another way to look at this	3476	compressed into a single callback invocation (another way to look at
3136	is that C<ev_async> watchers are level-triggered, set on C<ev_async_send>,	3477	this is that C<ev_async> watchers are level-triggered: they are set on
3137	reset when the event loop detects that).	3478	C<ev_async_send>, reset when the event loop detects that).
3138		3479
3139	This call incurs the overhead of a system call only once per event loop	3480	This call incurs the overhead of at most one extra system call per event
3140	iteration, so while the overhead might be noticeable, it doesn't apply to	3481	loop iteration, if the event loop is blocked, and no syscall at all if
3141	repeated calls to C<ev_async_send> for the same event loop.	3482	the event loop (or your program) is processing events. That means that
		3483	repeated calls are basically free (there is no need to avoid calls for
		3484	performance reasons) and that the overhead becomes smaller (typically
		3485	zero) under load.
3142		3486
3143	=item bool = ev_async_pending (ev_async *)	3487	=item bool = ev_async_pending (ev_async *)
3144		3488
3145	Returns a non-zero value when C<ev_async_send> has been called on the	3489	Returns a non-zero value when C<ev_async_send> has been called on the
3146	watcher but the event has not yet been processed (or even noted) by the	3490	watcher but the event has not yet been processed (or even noted) by the
…		…
3179		3523
3180	If C<timeout> is less than 0, then no timeout watcher will be	3524	If C<timeout> is less than 0, then no timeout watcher will be
3181	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and	3525	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and
3182	repeat = 0) will be started. C<0> is a valid timeout.	3526	repeat = 0) will be started. C<0> is a valid timeout.
3183		3527
3184	The callback has the type C<void (*cb)(int revents, void *arg)> and gets	3528	The callback has the type C<void (*cb)(int revents, void *arg)> and is
3185	passed an C<revents> set like normal event callbacks (a combination of	3529	passed an C<revents> set like normal event callbacks (a combination of
3186	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>	3530	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMER>) and the C<arg>
3187	value passed to C<ev_once>. Note that it is possible to receive I<both>	3531	value passed to C<ev_once>. Note that it is possible to receive I<both>
3188	a timeout and an io event at the same time - you probably should give io	3532	a timeout and an io event at the same time - you probably should give io
3189	events precedence.	3533	events precedence.
3190		3534
3191	Example: wait up to ten seconds for data to appear on STDIN_FILENO.	3535	Example: wait up to ten seconds for data to appear on STDIN_FILENO.
3192		3536
3193	static void stdin_ready (int revents, void *arg)	3537	static void stdin_ready (int revents, void *arg)
3194	{	3538	{
3195	if (revents & EV_READ)	3539	if (revents & EV_READ)
3196	/* stdin might have data for us, joy! */;	3540	/* stdin might have data for us, joy! */;
3197	else if (revents & EV_TIMEOUT)	3541	else if (revents & EV_TIMER)
3198	/* doh, nothing entered */;	3542	/* doh, nothing entered */;
3199	}	3543	}
3200		3544
3201	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	3545	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
3202		3546
3203	=item ev_feed_fd_event (loop, int fd, int revents)	3547	=item ev_feed_fd_event (loop, int fd, int revents)
3204		3548
3205	Feed an event on the given fd, as if a file descriptor backend detected	3549	Feed an event on the given fd, as if a file descriptor backend detected
3206	the given events it.	3550	the given events.
3207		3551
3208	=item ev_feed_signal_event (loop, int signum)	3552	=item ev_feed_signal_event (loop, int signum)
3209		3553
3210	Feed an event as if the given signal occurred (C<loop> must be the default	3554	Feed an event as if the given signal occurred. See also C<ev_feed_signal>,
3211	loop!).	3555	which is async-safe.
3212		3556
3213	=back	3557	=back
		3558
		3559
		3560	=head1 COMMON OR USEFUL IDIOMS (OR BOTH)
		3561
		3562	This section explains some common idioms that are not immediately
		3563	obvious. Note that examples are sprinkled over the whole manual, and this
		3564	section only contains stuff that wouldn't fit anywhere else.
		3565
		3566	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
		3567
		3568	Each watcher has, by default, a C<void *data> member that you can read
		3569	or modify at any time: libev will completely ignore it. This can be used
		3570	to associate arbitrary data with your watcher. If you need more data and
		3571	don't want to allocate memory separately and store a pointer to it in that
		3572	data member, you can also "subclass" the watcher type and provide your own
		3573	data:
		3574
		3575	struct my_io
		3576	{
		3577	ev_io io;
		3578	int otherfd;
		3579	void *somedata;
		3580	struct whatever *mostinteresting;
		3581	};
		3582
		3583	...
		3584	struct my_io w;
		3585	ev_io_init (&w.io, my_cb, fd, EV_READ);
		3586
		3587	And since your callback will be called with a pointer to the watcher, you
		3588	can cast it back to your own type:
		3589
		3590	static void my_cb (struct ev_loop *loop, ev_io *w_, int revents)
		3591	{
		3592	struct my_io *w = (struct my_io *)w_;
		3593	...
		3594	}
		3595
		3596	More interesting and less C-conformant ways of casting your callback
		3597	function type instead have been omitted.
		3598
		3599	=head2 BUILDING YOUR OWN COMPOSITE WATCHERS
		3600
		3601	Another common scenario is to use some data structure with multiple
		3602	embedded watchers, in effect creating your own watcher that combines
		3603	multiple libev event sources into one "super-watcher":
		3604
		3605	struct my_biggy
		3606	{
		3607	int some_data;
		3608	ev_timer t1;
		3609	ev_timer t2;
		3610	}
		3611
		3612	In this case getting the pointer to C<my_biggy> is a bit more
		3613	complicated: Either you store the address of your C<my_biggy> struct in
		3614	the C<data> member of the watcher (for woozies or C++ coders), or you need
		3615	to use some pointer arithmetic using C<offsetof> inside your watchers (for
		3616	real programmers):
		3617
		3618	#include <stddef.h>
		3619
		3620	static void
		3621	t1_cb (EV_P_ ev_timer *w, int revents)
		3622	{
		3623	struct my_biggy big = (struct my_biggy *)
		3624	(((char *)w) - offsetof (struct my_biggy, t1));
		3625	}
		3626
		3627	static void
		3628	t2_cb (EV_P_ ev_timer *w, int revents)
		3629	{
		3630	struct my_biggy big = (struct my_biggy *)
		3631	(((char *)w) - offsetof (struct my_biggy, t2));
		3632	}
		3633
		3634	=head2 AVOIDING FINISHING BEFORE RETURNING
		3635
		3636	Often you have structures like this in event-based programs:
		3637
		3638	callback ()
		3639	{
		3640	free (request);
		3641	}
		3642
		3643	request = start_new_request (..., callback);
		3644
		3645	The intent is to start some "lengthy" operation. The C<request> could be
		3646	used to cancel the operation, or do other things with it.
		3647
		3648	It's not uncommon to have code paths in C<start_new_request> that
		3649	immediately invoke the callback, for example, to report errors. Or you add
		3650	some caching layer that finds that it can skip the lengthy aspects of the
		3651	operation and simply invoke the callback with the result.
		3652
		3653	The problem here is that this will happen I<before> C<start_new_request>
		3654	has returned, so C<request> is not set.
		3655
		3656	Even if you pass the request by some safer means to the callback, you
		3657	might want to do something to the request after starting it, such as
		3658	canceling it, which probably isn't working so well when the callback has
		3659	already been invoked.
		3660
		3661	A common way around all these issues is to make sure that
		3662	C<start_new_request> I<always> returns before the callback is invoked. If
		3663	C<start_new_request> immediately knows the result, it can artificially
		3664	delay invoking the callback by e.g. using a C<prepare> or C<idle> watcher
		3665	for example, or more sneakily, by reusing an existing (stopped) watcher
		3666	and pushing it into the pending queue:
		3667
		3668	ev_set_cb (watcher, callback);
		3669	ev_feed_event (EV_A_ watcher, 0);
		3670
		3671	This way, C<start_new_request> can safely return before the callback is
		3672	invoked, while not delaying callback invocation too much.
		3673
		3674	=head2 MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS
		3675
		3676	Often (especially in GUI toolkits) there are places where you have
		3677	I<modal> interaction, which is most easily implemented by recursively
		3678	invoking C<ev_run>.
		3679
		3680	This brings the problem of exiting - a callback might want to finish the
		3681	main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but
		3682	a modal "Are you sure?" dialog is still waiting), or just the nested one
		3683	and not the main one (e.g. user clocked "Ok" in a modal dialog), or some
		3684	other combination: In these cases, C<ev_break> will not work alone.
		3685
		3686	The solution is to maintain "break this loop" variable for each C<ev_run>
		3687	invocation, and use a loop around C<ev_run> until the condition is
		3688	triggered, using C<EVRUN_ONCE>:
		3689
		3690	// main loop
		3691	int exit_main_loop = 0;
		3692
		3693	while (!exit_main_loop)
		3694	ev_run (EV_DEFAULT_ EVRUN_ONCE);
		3695
		3696	// in a modal watcher
		3697	int exit_nested_loop = 0;
		3698
		3699	while (!exit_nested_loop)
		3700	ev_run (EV_A_ EVRUN_ONCE);
		3701
		3702	To exit from any of these loops, just set the corresponding exit variable:
		3703
		3704	// exit modal loop
		3705	exit_nested_loop = 1;
		3706
		3707	// exit main program, after modal loop is finished
		3708	exit_main_loop = 1;
		3709
		3710	// exit both
		3711	exit_main_loop = exit_nested_loop = 1;
		3712
		3713	=head2 THREAD LOCKING EXAMPLE
		3714
		3715	Here is a fictitious example of how to run an event loop in a different
		3716	thread from where callbacks are being invoked and watchers are
		3717	created/added/removed.
		3718
		3719	For a real-world example, see the C<EV::Loop::Async> perl module,
		3720	which uses exactly this technique (which is suited for many high-level
		3721	languages).
		3722
		3723	The example uses a pthread mutex to protect the loop data, a condition
		3724	variable to wait for callback invocations, an async watcher to notify the
		3725	event loop thread and an unspecified mechanism to wake up the main thread.
		3726
		3727	First, you need to associate some data with the event loop:
		3728
		3729	typedef struct {
		3730	mutex_t lock; /* global loop lock */
		3731	ev_async async_w;
		3732	thread_t tid;
		3733	cond_t invoke_cv;
		3734	} userdata;
		3735
		3736	void prepare_loop (EV_P)
		3737	{
		3738	// for simplicity, we use a static userdata struct.
		3739	static userdata u;
		3740
		3741	ev_async_init (&u->async_w, async_cb);
		3742	ev_async_start (EV_A_ &u->async_w);
		3743
		3744	pthread_mutex_init (&u->lock, 0);
		3745	pthread_cond_init (&u->invoke_cv, 0);
		3746
		3747	// now associate this with the loop
		3748	ev_set_userdata (EV_A_ u);
		3749	ev_set_invoke_pending_cb (EV_A_ l_invoke);
		3750	ev_set_loop_release_cb (EV_A_ l_release, l_acquire);
		3751
		3752	// then create the thread running ev_run
		3753	pthread_create (&u->tid, 0, l_run, EV_A);
		3754	}
		3755
		3756	The callback for the C<ev_async> watcher does nothing: the watcher is used
		3757	solely to wake up the event loop so it takes notice of any new watchers
		3758	that might have been added:
		3759
		3760	static void
		3761	async_cb (EV_P_ ev_async *w, int revents)
		3762	{
		3763	// just used for the side effects
		3764	}
		3765
		3766	The C<l_release> and C<l_acquire> callbacks simply unlock/lock the mutex
		3767	protecting the loop data, respectively.
		3768
		3769	static void
		3770	l_release (EV_P)
		3771	{
		3772	userdata *u = ev_userdata (EV_A);
		3773	pthread_mutex_unlock (&u->lock);
		3774	}
		3775
		3776	static void
		3777	l_acquire (EV_P)
		3778	{
		3779	userdata *u = ev_userdata (EV_A);
		3780	pthread_mutex_lock (&u->lock);
		3781	}
		3782
		3783	The event loop thread first acquires the mutex, and then jumps straight
		3784	into C<ev_run>:
		3785
		3786	void *
		3787	l_run (void *thr_arg)
		3788	{
		3789	struct ev_loop *loop = (struct ev_loop *)thr_arg;
		3790
		3791	l_acquire (EV_A);
		3792	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
		3793	ev_run (EV_A_ 0);
		3794	l_release (EV_A);
		3795
		3796	return 0;
		3797	}
		3798
		3799	Instead of invoking all pending watchers, the C<l_invoke> callback will
		3800	signal the main thread via some unspecified mechanism (signals? pipe
		3801	writes? C<Async::Interrupt>?) and then waits until all pending watchers
		3802	have been called (in a while loop because a) spurious wakeups are possible
		3803	and b) skipping inter-thread-communication when there are no pending
		3804	watchers is very beneficial):
		3805
		3806	static void
		3807	l_invoke (EV_P)
		3808	{
		3809	userdata *u = ev_userdata (EV_A);
		3810
		3811	while (ev_pending_count (EV_A))
		3812	{
		3813	wake_up_other_thread_in_some_magic_or_not_so_magic_way ();
		3814	pthread_cond_wait (&u->invoke_cv, &u->lock);
		3815	}
		3816	}
		3817
		3818	Now, whenever the main thread gets told to invoke pending watchers, it
		3819	will grab the lock, call C<ev_invoke_pending> and then signal the loop
		3820	thread to continue:
		3821
		3822	static void
		3823	real_invoke_pending (EV_P)
		3824	{
		3825	userdata *u = ev_userdata (EV_A);
		3826
		3827	pthread_mutex_lock (&u->lock);
		3828	ev_invoke_pending (EV_A);
		3829	pthread_cond_signal (&u->invoke_cv);
		3830	pthread_mutex_unlock (&u->lock);
		3831	}
		3832
		3833	Whenever you want to start/stop a watcher or do other modifications to an
		3834	event loop, you will now have to lock:
		3835
		3836	ev_timer timeout_watcher;
		3837	userdata *u = ev_userdata (EV_A);
		3838
		3839	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
		3840
		3841	pthread_mutex_lock (&u->lock);
		3842	ev_timer_start (EV_A_ &timeout_watcher);
		3843	ev_async_send (EV_A_ &u->async_w);
		3844	pthread_mutex_unlock (&u->lock);
		3845
		3846	Note that sending the C<ev_async> watcher is required because otherwise
		3847	an event loop currently blocking in the kernel will have no knowledge
		3848	about the newly added timer. By waking up the loop it will pick up any new
		3849	watchers in the next event loop iteration.
		3850
		3851	=head2 THREADS, COROUTINES, CONTINUATIONS, QUEUES... INSTEAD OF CALLBACKS
		3852
		3853	While the overhead of a callback that e.g. schedules a thread is small, it
		3854	is still an overhead. If you embed libev, and your main usage is with some
		3855	kind of threads or coroutines, you might want to customise libev so that
		3856	doesn't need callbacks anymore.
		3857
		3858	Imagine you have coroutines that you can switch to using a function
		3859	C<switch_to (coro)>, that libev runs in a coroutine called C<libev_coro>
		3860	and that due to some magic, the currently active coroutine is stored in a
		3861	global called C<current_coro>. Then you can build your own "wait for libev
		3862	event" primitive by changing C<EV_CB_DECLARE> and C<EV_CB_INVOKE> (note
		3863	the differing C<;> conventions):
		3864
		3865	#define EV_CB_DECLARE(type) struct my_coro *cb;
		3866	#define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb)
		3867
		3868	That means instead of having a C callback function, you store the
		3869	coroutine to switch to in each watcher, and instead of having libev call
		3870	your callback, you instead have it switch to that coroutine.
		3871
		3872	A coroutine might now wait for an event with a function called
		3873	C<wait_for_event>. (the watcher needs to be started, as always, but it doesn't
		3874	matter when, or whether the watcher is active or not when this function is
		3875	called):
		3876
		3877	void
		3878	wait_for_event (ev_watcher *w)
		3879	{
		3880	ev_set_cb (w, current_coro);
		3881	switch_to (libev_coro);
		3882	}
		3883
		3884	That basically suspends the coroutine inside C<wait_for_event> and
		3885	continues the libev coroutine, which, when appropriate, switches back to
		3886	this or any other coroutine.
		3887
		3888	You can do similar tricks if you have, say, threads with an event queue -
		3889	instead of storing a coroutine, you store the queue object and instead of
		3890	switching to a coroutine, you push the watcher onto the queue and notify
		3891	any waiters.
		3892
		3893	To embed libev, see L</EMBEDDING>, but in short, it's easiest to create two
		3894	files, F<my_ev.h> and F<my_ev.c> that include the respective libev files:
		3895
		3896	// my_ev.h
		3897	#define EV_CB_DECLARE(type) struct my_coro *cb;
		3898	#define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb);
		3899	#include "../libev/ev.h"
		3900
		3901	// my_ev.c
		3902	#define EV_H "my_ev.h"
		3903	#include "../libev/ev.c"
		3904
		3905	And then use F<my_ev.h> when you would normally use F<ev.h>, and compile
		3906	F<my_ev.c> into your project. When properly specifying include paths, you
		3907	can even use F<ev.h> as header file name directly.
3214		3908
3215		3909
3216	=head1 LIBEVENT EMULATION	3910	=head1 LIBEVENT EMULATION
3217		3911
3218	Libev offers a compatibility emulation layer for libevent. It cannot	3912	Libev offers a compatibility emulation layer for libevent. It cannot
3219	emulate the internals of libevent, so here are some usage hints:	3913	emulate the internals of libevent, so here are some usage hints:
3220		3914
3221	=over 4	3915	=over 4
		3916
		3917	=item * Only the libevent-1.4.1-beta API is being emulated.
		3918
		3919	This was the newest libevent version available when libev was implemented,
		3920	and is still mostly unchanged in 2010.
3222		3921
3223	=item * Use it by including <event.h>, as usual.	3922	=item * Use it by including <event.h>, as usual.
3224		3923
3225	=item * The following members are fully supported: ev_base, ev_callback,	3924	=item * The following members are fully supported: ev_base, ev_callback,
3226	ev_arg, ev_fd, ev_res, ev_events.	3925	ev_arg, ev_fd, ev_res, ev_events.
…		…
3232	=item * Priorities are not currently supported. Initialising priorities	3931	=item * Priorities are not currently supported. Initialising priorities
3233	will fail and all watchers will have the same priority, even though there	3932	will fail and all watchers will have the same priority, even though there
3234	is an ev_pri field.	3933	is an ev_pri field.
3235		3934
3236	=item * In libevent, the last base created gets the signals, in libev, the	3935	=item * In libevent, the last base created gets the signals, in libev, the
3237	first base created (== the default loop) gets the signals.	3936	base that registered the signal gets the signals.
3238		3937
3239	=item * Other members are not supported.	3938	=item * Other members are not supported.
3240		3939
3241	=item * The libev emulation is I<not> ABI compatible to libevent, you need	3940	=item * The libev emulation is I<not> ABI compatible to libevent, you need
3242	to use the libev header file and library.	3941	to use the libev header file and library.
3243		3942
3244	=back	3943	=back
3245		3944
3246	=head1 C++ SUPPORT	3945	=head1 C++ SUPPORT
		3946
		3947	=head2 C API
		3948
		3949	The normal C API should work fine when used from C++: both ev.h and the
		3950	libev sources can be compiled as C++. Therefore, code that uses the C API
		3951	will work fine.
		3952
		3953	Proper exception specifications might have to be added to callbacks passed
		3954	to libev: exceptions may be thrown only from watcher callbacks, all
		3955	other callbacks (allocator, syserr, loop acquire/release and periodioc
		3956	reschedule callbacks) must not throw exceptions, and might need a C<throw
		3957	()> specification. If you have code that needs to be compiled as both C
		3958	and C++ you can use the C<EV_THROW> macro for this:
		3959
		3960	static void
		3961	fatal_error (const char *msg) EV_THROW
		3962	{
		3963	perror (msg);
		3964	abort ();
		3965	}
		3966
		3967	...
		3968	ev_set_syserr_cb (fatal_error);
		3969
		3970	The only API functions that can currently throw exceptions are C<ev_run>,
		3971	C<ev_invoke>, C<ev_invoke_pending> and C<ev_loop_destroy> (the latter
		3972	because it runs cleanup watchers).
		3973
		3974	Throwing exceptions in watcher callbacks is only supported if libev itself
		3975	is compiled with a C++ compiler or your C and C++ environments allow
		3976	throwing exceptions through C libraries (most do).
		3977
		3978	=head2 C++ API
3247		3979
3248	Libev comes with some simplistic wrapper classes for C++ that mainly allow	3980	Libev comes with some simplistic wrapper classes for C++ that mainly allow
3249	you to use some convenience methods to start/stop watchers and also change	3981	you to use some convenience methods to start/stop watchers and also change
3250	the callback model to a model using method callbacks on objects.	3982	the callback model to a model using method callbacks on objects.
3251		3983
…		…
3261	Care has been taken to keep the overhead low. The only data member the C++	3993	Care has been taken to keep the overhead low. The only data member the C++
3262	classes add (compared to plain C-style watchers) is the event loop pointer	3994	classes add (compared to plain C-style watchers) is the event loop pointer
3263	that the watcher is associated with (or no additional members at all if	3995	that the watcher is associated with (or no additional members at all if
3264	you disable C<EV_MULTIPLICITY> when embedding libev).	3996	you disable C<EV_MULTIPLICITY> when embedding libev).
3265		3997
3266	Currently, functions, and static and non-static member functions can be	3998	Currently, functions, static and non-static member functions and classes
3267	used as callbacks. Other types should be easy to add as long as they only	3999	with C<operator ()> can be used as callbacks. Other types should be easy
3268	need one additional pointer for context. If you need support for other	4000	to add as long as they only need one additional pointer for context. If
3269	types of functors please contact the author (preferably after implementing	4001	you need support for other types of functors please contact the author
3270	it).	4002	(preferably after implementing it).
		4003
		4004	For all this to work, your C++ compiler either has to use the same calling
		4005	conventions as your C compiler (for static member functions), or you have
		4006	to embed libev and compile libev itself as C++.
3271		4007
3272	Here is a list of things available in the C<ev> namespace:	4008	Here is a list of things available in the C<ev> namespace:
3273		4009
3274	=over 4	4010	=over 4
3275		4011
…		…
3285	=item C<ev::io>, C<ev::timer>, C<ev::periodic>, C<ev::idle>, C<ev::sig> etc.	4021	=item C<ev::io>, C<ev::timer>, C<ev::periodic>, C<ev::idle>, C<ev::sig> etc.
3286		4022
3287	For each C<ev_TYPE> watcher in F<ev.h> there is a corresponding class of	4023	For each C<ev_TYPE> watcher in F<ev.h> there is a corresponding class of
3288	the same name in the C<ev> namespace, with the exception of C<ev_signal>	4024	the same name in the C<ev> namespace, with the exception of C<ev_signal>
3289	which is called C<ev::sig> to avoid clashes with the C<signal> macro	4025	which is called C<ev::sig> to avoid clashes with the C<signal> macro
3290	defines by many implementations.	4026	defined by many implementations.
3291		4027
3292	All of those classes have these methods:	4028	All of those classes have these methods:
3293		4029
3294	=over 4	4030	=over 4
3295		4031
…		…
3336	myclass obj;	4072	myclass obj;
3337	ev::io iow;	4073	ev::io iow;
3338	iow.set <myclass, &myclass::io_cb> (&obj);	4074	iow.set <myclass, &myclass::io_cb> (&obj);
3339		4075
3340	=item w->set (object *)	4076	=item w->set (object *)
3341
3342	This is an B<experimental> feature that might go away in a future version.
3343		4077
3344	This is a variation of a method callback - leaving out the method to call	4078	This is a variation of a method callback - leaving out the method to call
3345	will default the method to C<operator ()>, which makes it possible to use	4079	will default the method to C<operator ()>, which makes it possible to use
3346	functor objects without having to manually specify the C<operator ()> all	4080	functor objects without having to manually specify the C<operator ()> all
3347	the time. Incidentally, you can then also leave out the template argument	4081	the time. Incidentally, you can then also leave out the template argument
…		…
3387	Associates a different C<struct ev_loop> with this watcher. You can only	4121	Associates a different C<struct ev_loop> with this watcher. You can only
3388	do this when the watcher is inactive (and not pending either).	4122	do this when the watcher is inactive (and not pending either).
3389		4123
3390	=item w->set ([arguments])	4124	=item w->set ([arguments])
3391		4125
3392	Basically the same as C<ev_TYPE_set>, with the same arguments. Must be	4126	Basically the same as C<ev_TYPE_set>, with the same arguments. Either this
3393	called at least once. Unlike the C counterpart, an active watcher gets	4127	method or a suitable start method must be called at least once. Unlike the
3394	automatically stopped and restarted when reconfiguring it with this	4128	C counterpart, an active watcher gets automatically stopped and restarted
3395	method.	4129	when reconfiguring it with this method.
3396		4130
3397	=item w->start ()	4131	=item w->start ()
3398		4132
3399	Starts the watcher. Note that there is no C<loop> argument, as the	4133	Starts the watcher. Note that there is no C<loop> argument, as the
3400	constructor already stores the event loop.	4134	constructor already stores the event loop.
3401		4135
		4136	=item w->start ([arguments])
		4137
		4138	Instead of calling C<set> and C<start> methods separately, it is often
		4139	convenient to wrap them in one call. Uses the same type of arguments as
		4140	the configure C<set> method of the watcher.
		4141
3402	=item w->stop ()	4142	=item w->stop ()
3403		4143
3404	Stops the watcher if it is active. Again, no C<loop> argument.	4144	Stops the watcher if it is active. Again, no C<loop> argument.
3405		4145
3406	=item w->again () (C<ev::timer>, C<ev::periodic> only)	4146	=item w->again () (C<ev::timer>, C<ev::periodic> only)
…		…
3418		4158
3419	=back	4159	=back
3420		4160
3421	=back	4161	=back
3422		4162
3423	Example: Define a class with an IO and idle watcher, start one of them in	4163	Example: Define a class with two I/O and idle watchers, start the I/O
3424	the constructor.	4164	watchers in the constructor.
3425		4165
3426	class myclass	4166	class myclass
3427	{	4167	{
3428	ev::io io ; void io_cb (ev::io &w, int revents);	4168	ev::io io ; void io_cb (ev::io &w, int revents);
		4169	ev::io io2 ; void io2_cb (ev::io &w, int revents);
3429	ev::idle idle; void idle_cb (ev::idle &w, int revents);	4170	ev::idle idle; void idle_cb (ev::idle &w, int revents);
3430		4171
3431	myclass (int fd)	4172	myclass (int fd)
3432	{	4173	{
3433	io .set <myclass, &myclass::io_cb > (this);	4174	io .set <myclass, &myclass::io_cb > (this);
		4175	io2 .set <myclass, &myclass::io2_cb > (this);
3434	idle.set <myclass, &myclass::idle_cb> (this);	4176	idle.set <myclass, &myclass::idle_cb> (this);
3435		4177
3436	io.start (fd, ev::READ);	4178	io.set (fd, ev::WRITE); // configure the watcher
		4179	io.start (); // start it whenever convenient
		4180
		4181	io2.start (fd, ev::READ); // set + start in one call
3437	}	4182	}
3438	};	4183	};
3439		4184
3440		4185
3441	=head1 OTHER LANGUAGE BINDINGS	4186	=head1 OTHER LANGUAGE BINDINGS
…		…
3480	L<http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hlibev>.	4225	L<http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hlibev>.
3481		4226
3482	=item D	4227	=item D
3483		4228
3484	Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to	4229	Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to
3485	be found at L<http://proj.llucax.com.ar/wiki/evd>.	4230	be found at L<http://www.llucax.com.ar/proj/ev.d/index.html>.
3486		4231
3487	=item Ocaml	4232	=item Ocaml
3488		4233
3489	Erkki Seppala has written Ocaml bindings for libev, to be found at	4234	Erkki Seppala has written Ocaml bindings for libev, to be found at
3490	L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>.	4235	L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>.
…		…
3493		4238
3494	Brian Maher has written a partial interface to libev for lua (at the	4239	Brian Maher has written a partial interface to libev for lua (at the
3495	time of this writing, only C<ev_io> and C<ev_timer>), to be found at	4240	time of this writing, only C<ev_io> and C<ev_timer>), to be found at
3496	L<http://github.com/brimworks/lua-ev>.	4241	L<http://github.com/brimworks/lua-ev>.
3497		4242
		4243	=item Javascript
		4244
		4245	Node.js (L<http://nodejs.org>) uses libev as the underlying event library.
		4246
		4247	=item Others
		4248
		4249	There are others, and I stopped counting.
		4250
3498	=back	4251	=back
3499		4252
3500		4253
3501	=head1 MACRO MAGIC	4254	=head1 MACRO MAGIC
3502		4255
…		…
3515	loop argument"). The C<EV_A> form is used when this is the sole argument,	4268	loop argument"). The C<EV_A> form is used when this is the sole argument,
3516	C<EV_A_> is used when other arguments are following. Example:	4269	C<EV_A_> is used when other arguments are following. Example:
3517		4270
3518	ev_unref (EV_A);	4271	ev_unref (EV_A);
3519	ev_timer_add (EV_A_ watcher);	4272	ev_timer_add (EV_A_ watcher);
3520	ev_loop (EV_A_ 0);	4273	ev_run (EV_A_ 0);
3521		4274
3522	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	4275	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
3523	which is often provided by the following macro.	4276	which is often provided by the following macro.
3524		4277
3525	=item C<EV_P>, C<EV_P_>	4278	=item C<EV_P>, C<EV_P_>
…		…
3538	suitable for use with C<EV_A>.	4291	suitable for use with C<EV_A>.
3539		4292
3540	=item C<EV_DEFAULT>, C<EV_DEFAULT_>	4293	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
3541		4294
3542	Similar to the other two macros, this gives you the value of the default	4295	Similar to the other two macros, this gives you the value of the default
3543	loop, if multiple loops are supported ("ev loop default").	4296	loop, if multiple loops are supported ("ev loop default"). The default loop
		4297	will be initialised if it isn't already initialised.
		4298
		4299	For non-multiplicity builds, these macros do nothing, so you always have
		4300	to initialise the loop somewhere.
3544		4301
3545	=item C<EV_DEFAULT_UC>, C<EV_DEFAULT_UC_>	4302	=item C<EV_DEFAULT_UC>, C<EV_DEFAULT_UC_>
3546		4303
3547	Usage identical to C<EV_DEFAULT> and C<EV_DEFAULT_>, but requires that the	4304	Usage identical to C<EV_DEFAULT> and C<EV_DEFAULT_>, but requires that the
3548	default loop has been initialised (C<UC> == unchecked). Their behaviour	4305	default loop has been initialised (C<UC> == unchecked). Their behaviour
…		…
3565	}	4322	}
3566		4323
3567	ev_check check;	4324	ev_check check;
3568	ev_check_init (&check, check_cb);	4325	ev_check_init (&check, check_cb);
3569	ev_check_start (EV_DEFAULT_ &check);	4326	ev_check_start (EV_DEFAULT_ &check);
3570	ev_loop (EV_DEFAULT_ 0);	4327	ev_run (EV_DEFAULT_ 0);
3571		4328
3572	=head1 EMBEDDING	4329	=head1 EMBEDDING
3573		4330
3574	Libev can (and often is) directly embedded into host	4331	Libev can (and often is) directly embedded into host
3575	applications. Examples of applications that embed it include the Deliantra	4332	applications. Examples of applications that embed it include the Deliantra
…		…
3660	define before including (or compiling) any of its files. The default in	4417	define before including (or compiling) any of its files. The default in
3661	the absence of autoconf is documented for every option.	4418	the absence of autoconf is documented for every option.
3662		4419
3663	Symbols marked with "(h)" do not change the ABI, and can have different	4420	Symbols marked with "(h)" do not change the ABI, and can have different
3664	values when compiling libev vs. including F<ev.h>, so it is permissible	4421	values when compiling libev vs. including F<ev.h>, so it is permissible
3665	to redefine them before including F<ev.h> without breakign compatibility	4422	to redefine them before including F<ev.h> without breaking compatibility
3666	to a compiled library. All other symbols change the ABI, which means all	4423	to a compiled library. All other symbols change the ABI, which means all
3667	users of libev and the libev code itself must be compiled with compatible	4424	users of libev and the libev code itself must be compiled with compatible
3668	settings.	4425	settings.
3669		4426
3670	=over 4	4427	=over 4
		4428
		4429	=item EV_COMPAT3 (h)
		4430
		4431	Backwards compatibility is a major concern for libev. This is why this
		4432	release of libev comes with wrappers for the functions and symbols that
		4433	have been renamed between libev version 3 and 4.
		4434
		4435	You can disable these wrappers (to test compatibility with future
		4436	versions) by defining C<EV_COMPAT3> to C<0> when compiling your
		4437	sources. This has the additional advantage that you can drop the C<struct>
		4438	from C<struct ev_loop> declarations, as libev will provide an C<ev_loop>
		4439	typedef in that case.
		4440
		4441	In some future version, the default for C<EV_COMPAT3> will become C<0>,
		4442	and in some even more future version the compatibility code will be
		4443	removed completely.
3671		4444
3672	=item EV_STANDALONE (h)	4445	=item EV_STANDALONE (h)
3673		4446
3674	Must always be C<1> if you do not use autoconf configuration, which	4447	Must always be C<1> if you do not use autoconf configuration, which
3675	keeps libev from including F<config.h>, and it also defines dummy	4448	keeps libev from including F<config.h>, and it also defines dummy
…		…
3677	supported). It will also not define any of the structs usually found in	4450	supported). It will also not define any of the structs usually found in
3678	F<event.h> that are not directly supported by the libev core alone.	4451	F<event.h> that are not directly supported by the libev core alone.
3679		4452
3680	In standalone mode, libev will still try to automatically deduce the	4453	In standalone mode, libev will still try to automatically deduce the
3681	configuration, but has to be more conservative.	4454	configuration, but has to be more conservative.
		4455
		4456	=item EV_USE_FLOOR
		4457
		4458	If defined to be C<1>, libev will use the C<floor ()> function for its
		4459	periodic reschedule calculations, otherwise libev will fall back on a
		4460	portable (slower) implementation. If you enable this, you usually have to
		4461	link against libm or something equivalent. Enabling this when the C<floor>
		4462	function is not available will fail, so the safe default is to not enable
		4463	this.
3682		4464
3683	=item EV_USE_MONOTONIC	4465	=item EV_USE_MONOTONIC
3684		4466
3685	If defined to be C<1>, libev will try to detect the availability of the	4467	If defined to be C<1>, libev will try to detect the availability of the
3686	monotonic clock option at both compile time and runtime. Otherwise no	4468	monotonic clock option at both compile time and runtime. Otherwise no
…		…
3816	If defined to be C<1>, libev will compile in support for the Linux inotify	4598	If defined to be C<1>, libev will compile in support for the Linux inotify
3817	interface to speed up C<ev_stat> watchers. Its actual availability will	4599	interface to speed up C<ev_stat> watchers. Its actual availability will
3818	be detected at runtime. If undefined, it will be enabled if the headers	4600	be detected at runtime. If undefined, it will be enabled if the headers
3819	indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled.	4601	indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled.
3820		4602
		4603	=item EV_NO_SMP
		4604
		4605	If defined to be C<1>, libev will assume that memory is always coherent
		4606	between threads, that is, threads can be used, but threads never run on
		4607	different cpus (or different cpu cores). This reduces dependencies
		4608	and makes libev faster.
		4609
		4610	=item EV_NO_THREADS
		4611
		4612	If defined to be C<1>, libev will assume that it will never be called
		4613	from different threads, which is a stronger assumption than C<EV_NO_SMP>,
		4614	above. This reduces dependencies and makes libev faster.
		4615
3821	=item EV_ATOMIC_T	4616	=item EV_ATOMIC_T
3822		4617
3823	Libev requires an integer type (suitable for storing C<0> or C<1>) whose	4618	Libev requires an integer type (suitable for storing C<0> or C<1>) whose
3824	access is atomic with respect to other threads or signal contexts. No such	4619	access is atomic and serialised with respect to other threads or signal
3825	type is easily found in the C language, so you can provide your own type	4620	contexts. No such type is easily found in the C language, so you can
3826	that you know is safe for your purposes. It is used both for signal handler "locking"	4621	provide your own type that you know is safe for your purposes. It is used
3827	as well as for signal and thread safety in C<ev_async> watchers.	4622	both for signal handler "locking" as well as for signal and thread safety
		4623	in C<ev_async> watchers.
3828		4624
3829	In the absence of this define, libev will use C<sig_atomic_t volatile>	4625	In the absence of this define, libev will use C<sig_atomic_t volatile>
3830	(from F<signal.h>), which is usually good enough on most platforms.	4626	(from F<signal.h>), which is usually good enough on most platforms,
		4627	although strictly speaking using a type that also implies a memory fence
		4628	is required.
3831		4629
3832	=item EV_H (h)	4630	=item EV_H (h)
3833		4631
3834	The name of the F<ev.h> header file used to include it. The default if	4632	The name of the F<ev.h> header file used to include it. The default if
3835	undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be	4633	undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be
…		…
3859	will have the C<struct ev_loop *> as first argument, and you can create	4657	will have the C<struct ev_loop *> as first argument, and you can create
3860	additional independent event loops. Otherwise there will be no support	4658	additional independent event loops. Otherwise there will be no support
3861	for multiple event loops and there is no first event loop pointer	4659	for multiple event loops and there is no first event loop pointer
3862	argument. Instead, all functions act on the single default loop.	4660	argument. Instead, all functions act on the single default loop.
3863		4661
		4662	Note that C<EV_DEFAULT> and C<EV_DEFAULT_> will no longer provide a
		4663	default loop when multiplicity is switched off - you always have to
		4664	initialise the loop manually in this case.
		4665
3864	=item EV_MINPRI	4666	=item EV_MINPRI
3865		4667
3866	=item EV_MAXPRI	4668	=item EV_MAXPRI
3867		4669
3868	The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to	4670	The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to
…		…
3882	EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE,	4684	EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE,
3883	EV_ASYNC_ENABLE, EV_CHILD_ENABLE.	4685	EV_ASYNC_ENABLE, EV_CHILD_ENABLE.
3884		4686
3885	If undefined or defined to be C<1> (and the platform supports it), then	4687	If undefined or defined to be C<1> (and the platform supports it), then
3886	the respective watcher type is supported. If defined to be C<0>, then it	4688	the respective watcher type is supported. If defined to be C<0>, then it
3887	is not. Disabling watcher types mainly saves codesize.	4689	is not. Disabling watcher types mainly saves code size.
3888		4690
3889	=item EV_FEATURES	4691	=item EV_FEATURES
3890		4692
3891	If you need to shave off some kilobytes of code at the expense of some	4693	If you need to shave off some kilobytes of code at the expense of some
3892	speed (but with the full API), you can define this symbol to request	4694	speed (but with the full API), you can define this symbol to request
3893	certain subsets of functionality. The default is to enable all features	4695	certain subsets of functionality. The default is to enable all features
3894	that can be enabled on the platform.	4696	that can be enabled on the platform.
3895
3896	Note that using autoconf will usually override most of the features, so
3897	using this symbol makes sense mostly when embedding libev.
3898		4697
3899	A typical way to use this symbol is to define it to C<0> (or to a bitset	4698	A typical way to use this symbol is to define it to C<0> (or to a bitset
3900	with some broad features you want) and then selectively re-enable	4699	with some broad features you want) and then selectively re-enable
3901	additional parts you want, for example if you want everything minimal,	4700	additional parts you want, for example if you want everything minimal,
3902	but multiple event loop support, async and child watchers and the poll	4701	but multiple event loop support, async and child watchers and the poll
…		…
3907	#define EV_USE_POLL 1	4706	#define EV_USE_POLL 1
3908	#define EV_CHILD_ENABLE 1	4707	#define EV_CHILD_ENABLE 1
3909	#define EV_ASYNC_ENABLE 1	4708	#define EV_ASYNC_ENABLE 1
3910		4709
3911	The actual value is a bitset, it can be a combination of the following	4710	The actual value is a bitset, it can be a combination of the following
3912	values:	4711	values (by default, all of these are enabled):
3913		4712
3914	=over 4	4713	=over 4
3915		4714
3916	=item C<1> - faster/larger code	4715	=item C<1> - faster/larger code
3917		4716
3918	Use larger code to speed up some operations.	4717	Use larger code to speed up some operations.
3919		4718
3920	Currently this is used to override some inlining decisions (enlarging the roughly	4719	Currently this is used to override some inlining decisions (enlarging the
3921	30% code size on amd64.	4720	code size by roughly 30% on amd64).
3922		4721
3923	When optimising for size, use of compiler flags such as C<-Os> with	4722	When optimising for size, use of compiler flags such as C<-Os> with
3924	gcc recommended, as well as C<-DNDEBUG>, as libev contains a number of	4723	gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of
3925	assertions.	4724	assertions.
3926		4725
		4726	The default is off when C<__OPTIMIZE_SIZE__> is defined by your compiler
		4727	(e.g. gcc with C<-Os>).
		4728
3927	=item C<2> - faster/larger data structures	4729	=item C<2> - faster/larger data structures
3928		4730
3929	Replaces the small 2-heap for timer management by a faster 4-heap, larger	4731	Replaces the small 2-heap for timer management by a faster 4-heap, larger
3930	hash table sizes and so on. This will usually further increase codesize	4732	hash table sizes and so on. This will usually further increase code size
3931	and can additionally have an effect on the size of data structures at	4733	and can additionally have an effect on the size of data structures at
3932	runtime.	4734	runtime.
3933		4735
		4736	The default is off when C<__OPTIMIZE_SIZE__> is defined by your compiler
		4737	(e.g. gcc with C<-Os>).
		4738
3934	=item C<4> - full API configuration	4739	=item C<4> - full API configuration
3935		4740
3936	This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and	4741	This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and
3937	enables multiplicity (C<EV_MULTIPLICITY>=1).	4742	enables multiplicity (C<EV_MULTIPLICITY>=1).
3938		4743
		4744	=item C<8> - full API
		4745
3939	It also enables a lot of the "lesser used" core API functions. See C<ev.h>	4746	This enables a lot of the "lesser used" API functions. See C<ev.h> for
3940	for details on which parts of the API are still available without this	4747	details on which parts of the API are still available without this
3941	feature, and do not complain if this subset changes over time.	4748	feature, and do not complain if this subset changes over time.
3942		4749
3943	=item C<8> - enable all optional watcher types	4750	=item C<16> - enable all optional watcher types
3944		4751
3945	Enables all optional watcher types. If you want to selectively enable	4752	Enables all optional watcher types. If you want to selectively enable
3946	only some watcher types other than I/O and timers (e.g. prepare,	4753	only some watcher types other than I/O and timers (e.g. prepare,
3947	embed, async, child...) you can enable them manually by defining	4754	embed, async, child...) you can enable them manually by defining
3948	C<EV_watchertype_ENABLE> to C<1> instead.	4755	C<EV_watchertype_ENABLE> to C<1> instead.
3949		4756
3950	=item C<16> - enable all backends	4757	=item C<32> - enable all backends
3951		4758
3952	This enables all backends - without this feature, you need to enable at	4759	This enables all backends - without this feature, you need to enable at
3953	least one backend manually (C<EV_USE_SELECT> is a good choice).	4760	least one backend manually (C<EV_USE_SELECT> is a good choice).
3954		4761
3955	=item C<32> - enable OS-specific "helper" APIs	4762	=item C<64> - enable OS-specific "helper" APIs
3956		4763
3957	Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by	4764	Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by
3958	default.	4765	default.
3959		4766
3960	=back	4767	=back
3961		4768
3962	Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0>	4769	Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0>
3963	reduces the compiled size of libev from 24.7Kb to 6.5Kb on my GNU/Linux	4770	reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb
3964	amd64 system, while still giving you I/O watchers, timers and monotonic	4771	code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O
3965	clock support.	4772	watchers, timers and monotonic clock support.
3966		4773
3967	With an intelligent-enough linker (gcc+binutils are intelligent enough	4774	With an intelligent-enough linker (gcc+binutils are intelligent enough
3968	when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by	4775	when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by
3969	your program might be left out as well - a binary starting a timer and an	4776	your program might be left out as well - a binary starting a timer and an
3970	I/O watcher then might come out at only 5Kb.	4777	I/O watcher then might come out at only 5Kb.
3971		4778
		4779	=item EV_API_STATIC
		4780
		4781	If this symbol is defined (by default it is not), then all identifiers
		4782	will have static linkage. This means that libev will not export any
		4783	identifiers, and you cannot link against libev anymore. This can be useful
		4784	when you embed libev, only want to use libev functions in a single file,
		4785	and do not want its identifiers to be visible.
		4786
		4787	To use this, define C<EV_API_STATIC> and include F<ev.c> in the file that
		4788	wants to use libev.
		4789
		4790	This option only works when libev is compiled with a C compiler, as C++
		4791	doesn't support the required declaration syntax.
		4792
3972	=item EV_AVOID_STDIO	4793	=item EV_AVOID_STDIO
3973		4794
3974	If this is set to C<1> at compiletime, then libev will avoid using stdio	4795	If this is set to C<1> at compiletime, then libev will avoid using stdio
3975	functions (printf, scanf, perror etc.). This will increase the codesize	4796	functions (printf, scanf, perror etc.). This will increase the code size
3976	somewhat, but if your program doesn't otherwise depend on stdio and your	4797	somewhat, but if your program doesn't otherwise depend on stdio and your
3977	libc allows it, this avoids linking in the stdio library which is quite	4798	libc allows it, this avoids linking in the stdio library which is quite
3978	big.	4799	big.
3979		4800
3980	Note that error messages might become less precise when this option is	4801	Note that error messages might become less precise when this option is
…		…
3984		4805
3985	The highest supported signal number, +1 (or, the number of	4806	The highest supported signal number, +1 (or, the number of
3986	signals): Normally, libev tries to deduce the maximum number of signals	4807	signals): Normally, libev tries to deduce the maximum number of signals
3987	automatically, but sometimes this fails, in which case it can be	4808	automatically, but sometimes this fails, in which case it can be
3988	specified. Also, using a lower number than detected (C<32> should be	4809	specified. Also, using a lower number than detected (C<32> should be
3989	good for about any system in existance) can save some memory, as libev	4810	good for about any system in existence) can save some memory, as libev
3990	statically allocates some 12-24 bytes per signal number.	4811	statically allocates some 12-24 bytes per signal number.
3991		4812
3992	=item EV_PID_HASHSIZE	4813	=item EV_PID_HASHSIZE
3993		4814
3994	C<ev_child> watchers use a small hash table to distribute workload by	4815	C<ev_child> watchers use a small hash table to distribute workload by
…		…
4026	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it	4847	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
4027	will be C<0>.	4848	will be C<0>.
4028		4849
4029	=item EV_VERIFY	4850	=item EV_VERIFY
4030		4851
4031	Controls how much internal verification (see C<ev_loop_verify ()>) will	4852	Controls how much internal verification (see C<ev_verify ()>) will
4032	be done: If set to C<0>, no internal verification code will be compiled	4853	be done: If set to C<0>, no internal verification code will be compiled
4033	in. If set to C<1>, then verification code will be compiled in, but not	4854	in. If set to C<1>, then verification code will be compiled in, but not
4034	called. If set to C<2>, then the internal verification code will be	4855	called. If set to C<2>, then the internal verification code will be
4035	called once per loop, which can slow down libev. If set to C<3>, then the	4856	called once per loop, which can slow down libev. If set to C<3>, then the
4036	verification code will be called very frequently, which will slow down	4857	verification code will be called very frequently, which will slow down
…		…
4040	will be C<0>.	4861	will be C<0>.
4041		4862
4042	=item EV_COMMON	4863	=item EV_COMMON
4043		4864
4044	By default, all watchers have a C<void *data> member. By redefining	4865	By default, all watchers have a C<void *data> member. By redefining
4045	this macro to a something else you can include more and other types of	4866	this macro to something else you can include more and other types of
4046	members. You have to define it each time you include one of the files,	4867	members. You have to define it each time you include one of the files,
4047	though, and it must be identical each time.	4868	though, and it must be identical each time.
4048		4869
4049	For example, the perl EV module uses something like this:	4870	For example, the perl EV module uses something like this:
4050		4871
…		…
4103	file.	4924	file.
4104		4925
4105	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	4926	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
4106	that everybody includes and which overrides some configure choices:	4927	that everybody includes and which overrides some configure choices:
4107		4928
4108	#define EV_FEATURES 0	4929	#define EV_FEATURES 8
4109	#define EV_USE_SELECT 1	4930	#define EV_USE_SELECT 1
		4931	#define EV_PREPARE_ENABLE 1
		4932	#define EV_IDLE_ENABLE 1
		4933	#define EV_SIGNAL_ENABLE 1
		4934	#define EV_CHILD_ENABLE 1
		4935	#define EV_USE_STDEXCEPT 0
4110	#define EV_CONFIG_H <config.h>	4936	#define EV_CONFIG_H <config.h>
4111		4937
4112	#include "ev++.h"	4938	#include "ev++.h"
4113		4939
4114	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	4940	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
4115		4941
4116	#include "ev_cpp.h"	4942	#include "ev_cpp.h"
4117	#include "ev.c"	4943	#include "ev.c"
4118		4944
4119	=head1 INTERACTION WITH OTHER PROGRAMS OR LIBRARIES	4945	=head1 INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT
4120		4946
4121	=head2 THREADS AND COROUTINES	4947	=head2 THREADS AND COROUTINES
4122		4948
4123	=head3 THREADS	4949	=head3 THREADS
4124		4950
…		…
4175	default loop and triggering an C<ev_async> watcher from the default loop	5001	default loop and triggering an C<ev_async> watcher from the default loop
4176	watcher callback into the event loop interested in the signal.	5002	watcher callback into the event loop interested in the signal.
4177		5003
4178	=back	5004	=back
4179		5005
4180	=head4 THREAD LOCKING EXAMPLE	5006	See also L</THREAD LOCKING EXAMPLE>.
4181
4182	Here is a fictitious example of how to run an event loop in a different
4183	thread than where callbacks are being invoked and watchers are
4184	created/added/removed.
4185
4186	For a real-world example, see the C<EV::Loop::Async> perl module,
4187	which uses exactly this technique (which is suited for many high-level
4188	languages).
4189
4190	The example uses a pthread mutex to protect the loop data, a condition
4191	variable to wait for callback invocations, an async watcher to notify the
4192	event loop thread and an unspecified mechanism to wake up the main thread.
4193
4194	First, you need to associate some data with the event loop:
4195
4196	typedef struct {
4197	mutex_t lock; /* global loop lock */
4198	ev_async async_w;
4199	thread_t tid;
4200	cond_t invoke_cv;
4201	} userdata;
4202
4203	void prepare_loop (EV_P)
4204	{
4205	// for simplicity, we use a static userdata struct.
4206	static userdata u;
4207
4208	ev_async_init (&u->async_w, async_cb);
4209	ev_async_start (EV_A_ &u->async_w);
4210
4211	pthread_mutex_init (&u->lock, 0);
4212	pthread_cond_init (&u->invoke_cv, 0);
4213
4214	// now associate this with the loop
4215	ev_set_userdata (EV_A_ u);
4216	ev_set_invoke_pending_cb (EV_A_ l_invoke);
4217	ev_set_loop_release_cb (EV_A_ l_release, l_acquire);
4218
4219	// then create the thread running ev_loop
4220	pthread_create (&u->tid, 0, l_run, EV_A);
4221	}
4222
4223	The callback for the C<ev_async> watcher does nothing: the watcher is used
4224	solely to wake up the event loop so it takes notice of any new watchers
4225	that might have been added:
4226
4227	static void
4228	async_cb (EV_P_ ev_async *w, int revents)
4229	{
4230	// just used for the side effects
4231	}
4232
4233	The C<l_release> and C<l_acquire> callbacks simply unlock/lock the mutex
4234	protecting the loop data, respectively.
4235
4236	static void
4237	l_release (EV_P)
4238	{
4239	userdata *u = ev_userdata (EV_A);
4240	pthread_mutex_unlock (&u->lock);
4241	}
4242
4243	static void
4244	l_acquire (EV_P)
4245	{
4246	userdata *u = ev_userdata (EV_A);
4247	pthread_mutex_lock (&u->lock);
4248	}
4249
4250	The event loop thread first acquires the mutex, and then jumps straight
4251	into C<ev_loop>:
4252
4253	void *
4254	l_run (void *thr_arg)
4255	{
4256	struct ev_loop *loop = (struct ev_loop *)thr_arg;
4257
4258	l_acquire (EV_A);
4259	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
4260	ev_loop (EV_A_ 0);
4261	l_release (EV_A);
4262
4263	return 0;
4264	}
4265
4266	Instead of invoking all pending watchers, the C<l_invoke> callback will
4267	signal the main thread via some unspecified mechanism (signals? pipe
4268	writes? C<Async::Interrupt>?) and then waits until all pending watchers
4269	have been called (in a while loop because a) spurious wakeups are possible
4270	and b) skipping inter-thread-communication when there are no pending
4271	watchers is very beneficial):
4272
4273	static void
4274	l_invoke (EV_P)
4275	{
4276	userdata *u = ev_userdata (EV_A);
4277
4278	while (ev_pending_count (EV_A))
4279	{
4280	wake_up_other_thread_in_some_magic_or_not_so_magic_way ();
4281	pthread_cond_wait (&u->invoke_cv, &u->lock);
4282	}
4283	}
4284
4285	Now, whenever the main thread gets told to invoke pending watchers, it
4286	will grab the lock, call C<ev_invoke_pending> and then signal the loop
4287	thread to continue:
4288
4289	static void
4290	real_invoke_pending (EV_P)
4291	{
4292	userdata *u = ev_userdata (EV_A);
4293
4294	pthread_mutex_lock (&u->lock);
4295	ev_invoke_pending (EV_A);
4296	pthread_cond_signal (&u->invoke_cv);
4297	pthread_mutex_unlock (&u->lock);
4298	}
4299
4300	Whenever you want to start/stop a watcher or do other modifications to an
4301	event loop, you will now have to lock:
4302
4303	ev_timer timeout_watcher;
4304	userdata *u = ev_userdata (EV_A);
4305
4306	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
4307
4308	pthread_mutex_lock (&u->lock);
4309	ev_timer_start (EV_A_ &timeout_watcher);
4310	ev_async_send (EV_A_ &u->async_w);
4311	pthread_mutex_unlock (&u->lock);
4312
4313	Note that sending the C<ev_async> watcher is required because otherwise
4314	an event loop currently blocking in the kernel will have no knowledge
4315	about the newly added timer. By waking up the loop it will pick up any new
4316	watchers in the next event loop iteration.
4317		5007
4318	=head3 COROUTINES	5008	=head3 COROUTINES
4319		5009
4320	Libev is very accommodating to coroutines ("cooperative threads"):	5010	Libev is very accommodating to coroutines ("cooperative threads"):
4321	libev fully supports nesting calls to its functions from different	5011	libev fully supports nesting calls to its functions from different
4322	coroutines (e.g. you can call C<ev_loop> on the same loop from two	5012	coroutines (e.g. you can call C<ev_run> on the same loop from two
4323	different coroutines, and switch freely between both coroutines running	5013	different coroutines, and switch freely between both coroutines running
4324	the loop, as long as you don't confuse yourself). The only exception is	5014	the loop, as long as you don't confuse yourself). The only exception is
4325	that you must not do this from C<ev_periodic> reschedule callbacks.	5015	that you must not do this from C<ev_periodic> reschedule callbacks.
4326		5016
4327	Care has been taken to ensure that libev does not keep local state inside	5017	Care has been taken to ensure that libev does not keep local state inside
4328	C<ev_loop>, and other calls do not usually allow for coroutine switches as	5018	C<ev_run>, and other calls do not usually allow for coroutine switches as
4329	they do not call any callbacks.	5019	they do not call any callbacks.
4330		5020
4331	=head2 COMPILER WARNINGS	5021	=head2 COMPILER WARNINGS
4332		5022
4333	Depending on your compiler and compiler settings, you might get no or a	5023	Depending on your compiler and compiler settings, you might get no or a
…		…
4344	maintainable.	5034	maintainable.
4345		5035
4346	And of course, some compiler warnings are just plain stupid, or simply	5036	And of course, some compiler warnings are just plain stupid, or simply
4347	wrong (because they don't actually warn about the condition their message	5037	wrong (because they don't actually warn about the condition their message
4348	seems to warn about). For example, certain older gcc versions had some	5038	seems to warn about). For example, certain older gcc versions had some
4349	warnings that resulted an extreme number of false positives. These have	5039	warnings that resulted in an extreme number of false positives. These have
4350	been fixed, but some people still insist on making code warn-free with	5040	been fixed, but some people still insist on making code warn-free with
4351	such buggy versions.	5041	such buggy versions.
4352		5042
4353	While libev is written to generate as few warnings as possible,	5043	While libev is written to generate as few warnings as possible,
4354	"warn-free" code is not a goal, and it is recommended not to build libev	5044	"warn-free" code is not a goal, and it is recommended not to build libev
…		…
4390	I suggest using suppression lists.	5080	I suggest using suppression lists.
4391		5081
4392		5082
4393	=head1 PORTABILITY NOTES	5083	=head1 PORTABILITY NOTES
4394		5084
		5085	=head2 GNU/LINUX 32 BIT LIMITATIONS
		5086
		5087	GNU/Linux is the only common platform that supports 64 bit file/large file
		5088	interfaces but I<disables> them by default.
		5089
		5090	That means that libev compiled in the default environment doesn't support
		5091	files larger than 2GiB or so, which mainly affects C<ev_stat> watchers.
		5092
		5093	Unfortunately, many programs try to work around this GNU/Linux issue
		5094	by enabling the large file API, which makes them incompatible with the
		5095	standard libev compiled for their system.
		5096
		5097	Likewise, libev cannot enable the large file API itself as this would
		5098	suddenly make it incompatible to the default compile time environment,
		5099	i.e. all programs not using special compile switches.
		5100
		5101	=head2 OS/X AND DARWIN BUGS
		5102
		5103	The whole thing is a bug if you ask me - basically any system interface
		5104	you touch is broken, whether it is locales, poll, kqueue or even the
		5105	OpenGL drivers.
		5106
		5107	=head3 C<kqueue> is buggy
		5108
		5109	The kqueue syscall is broken in all known versions - most versions support
		5110	only sockets, many support pipes.
		5111
		5112	Libev tries to work around this by not using C<kqueue> by default on this
		5113	rotten platform, but of course you can still ask for it when creating a
		5114	loop - embedding a socket-only kqueue loop into a select-based one is
		5115	probably going to work well.
		5116
		5117	=head3 C<poll> is buggy
		5118
		5119	Instead of fixing C<kqueue>, Apple replaced their (working) C<poll>
		5120	implementation by something calling C<kqueue> internally around the 10.5.6
		5121	release, so now C<kqueue> I<and> C<poll> are broken.
		5122
		5123	Libev tries to work around this by not using C<poll> by default on
		5124	this rotten platform, but of course you can still ask for it when creating
		5125	a loop.
		5126
		5127	=head3 C<select> is buggy
		5128
		5129	All that's left is C<select>, and of course Apple found a way to fuck this
		5130	one up as well: On OS/X, C<select> actively limits the number of file
		5131	descriptors you can pass in to 1024 - your program suddenly crashes when
		5132	you use more.
		5133
		5134	There is an undocumented "workaround" for this - defining
		5135	C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should>
		5136	work on OS/X.
		5137
		5138	=head2 SOLARIS PROBLEMS AND WORKAROUNDS
		5139
		5140	=head3 C<errno> reentrancy
		5141
		5142	The default compile environment on Solaris is unfortunately so
		5143	thread-unsafe that you can't even use components/libraries compiled
		5144	without C<-D_REENTRANT> in a threaded program, which, of course, isn't
		5145	defined by default. A valid, if stupid, implementation choice.
		5146
		5147	If you want to use libev in threaded environments you have to make sure
		5148	it's compiled with C<_REENTRANT> defined.
		5149
		5150	=head3 Event port backend
		5151
		5152	The scalable event interface for Solaris is called "event
		5153	ports". Unfortunately, this mechanism is very buggy in all major
		5154	releases. If you run into high CPU usage, your program freezes or you get
		5155	a large number of spurious wakeups, make sure you have all the relevant
		5156	and latest kernel patches applied. No, I don't know which ones, but there
		5157	are multiple ones to apply, and afterwards, event ports actually work
		5158	great.
		5159
		5160	If you can't get it to work, you can try running the program by setting
		5161	the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and
		5162	C<select> backends.
		5163
		5164	=head2 AIX POLL BUG
		5165
		5166	AIX unfortunately has a broken C<poll.h> header. Libev works around
		5167	this by trying to avoid the poll backend altogether (i.e. it's not even
		5168	compiled in), which normally isn't a big problem as C<select> works fine
		5169	with large bitsets on AIX, and AIX is dead anyway.
		5170
4395	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS	5171	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
		5172
		5173	=head3 General issues
4396		5174
4397	Win32 doesn't support any of the standards (e.g. POSIX) that libev	5175	Win32 doesn't support any of the standards (e.g. POSIX) that libev
4398	requires, and its I/O model is fundamentally incompatible with the POSIX	5176	requires, and its I/O model is fundamentally incompatible with the POSIX
4399	model. Libev still offers limited functionality on this platform in	5177	model. Libev still offers limited functionality on this platform in
4400	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	5178	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
4401	descriptors. This only applies when using Win32 natively, not when using	5179	descriptors. This only applies when using Win32 natively, not when using
4402	e.g. cygwin.	5180	e.g. cygwin. Actually, it only applies to the microsofts own compilers,
		5181	as every compiler comes with a slightly differently broken/incompatible
		5182	environment.
4403		5183
4404	Lifting these limitations would basically require the full	5184	Lifting these limitations would basically require the full
4405	re-implementation of the I/O system. If you are into these kinds of	5185	re-implementation of the I/O system. If you are into this kind of thing,
4406	things, then note that glib does exactly that for you in a very portable	5186	then note that glib does exactly that for you in a very portable way (note
4407	way (note also that glib is the slowest event library known to man).	5187	also that glib is the slowest event library known to man).
4408		5188
4409	There is no supported compilation method available on windows except	5189	There is no supported compilation method available on windows except
4410	embedding it into other applications.	5190	embedding it into other applications.
4411		5191
4412	Sensible signal handling is officially unsupported by Microsoft - libev	5192	Sensible signal handling is officially unsupported by Microsoft - libev
…		…
4440	you do I<not> compile the F<ev.c> or any other embedded source files!):	5220	you do I<not> compile the F<ev.c> or any other embedded source files!):
4441		5221
4442	#include "evwrap.h"	5222	#include "evwrap.h"
4443	#include "ev.c"	5223	#include "ev.c"
4444		5224
4445	=over 4
4446
4447	=item The winsocket select function	5225	=head3 The winsocket C<select> function
4448		5226
4449	The winsocket C<select> function doesn't follow POSIX in that it	5227	The winsocket C<select> function doesn't follow POSIX in that it
4450	requires socket I<handles> and not socket I<file descriptors> (it is	5228	requires socket I<handles> and not socket I<file descriptors> (it is
4451	also extremely buggy). This makes select very inefficient, and also	5229	also extremely buggy). This makes select very inefficient, and also
4452	requires a mapping from file descriptors to socket handles (the Microsoft	5230	requires a mapping from file descriptors to socket handles (the Microsoft
…		…
4461	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */	5239	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
4462		5240
4463	Note that winsockets handling of fd sets is O(n), so you can easily get a	5241	Note that winsockets handling of fd sets is O(n), so you can easily get a
4464	complexity in the O(n²) range when using win32.	5242	complexity in the O(n²) range when using win32.
4465		5243
4466	=item Limited number of file descriptors	5244	=head3 Limited number of file descriptors
4467		5245
4468	Windows has numerous arbitrary (and low) limits on things.	5246	Windows has numerous arbitrary (and low) limits on things.
4469		5247
4470	Early versions of winsocket's select only supported waiting for a maximum	5248	Early versions of winsocket's select only supported waiting for a maximum
4471	of C<64> handles (probably owning to the fact that all windows kernels	5249	of C<64> handles (probably owning to the fact that all windows kernels
…		…
4486	runtime libraries. This might get you to about C<512> or C<2048> sockets	5264	runtime libraries. This might get you to about C<512> or C<2048> sockets
4487	(depending on windows version and/or the phase of the moon). To get more,	5265	(depending on windows version and/or the phase of the moon). To get more,
4488	you need to wrap all I/O functions and provide your own fd management, but	5266	you need to wrap all I/O functions and provide your own fd management, but
4489	the cost of calling select (O(n²)) will likely make this unworkable.	5267	the cost of calling select (O(n²)) will likely make this unworkable.
4490		5268
4491	=back
4492
4493	=head2 PORTABILITY REQUIREMENTS	5269	=head2 PORTABILITY REQUIREMENTS
4494		5270
4495	In addition to a working ISO-C implementation and of course the	5271	In addition to a working ISO-C implementation and of course the
4496	backend-specific APIs, libev relies on a few additional extensions:	5272	backend-specific APIs, libev relies on a few additional extensions:
4497		5273
…		…
4503	Libev assumes not only that all watcher pointers have the same internal	5279	Libev assumes not only that all watcher pointers have the same internal
4504	structure (guaranteed by POSIX but not by ISO C for example), but it also	5280	structure (guaranteed by POSIX but not by ISO C for example), but it also
4505	assumes that the same (machine) code can be used to call any watcher	5281	assumes that the same (machine) code can be used to call any watcher
4506	callback: The watcher callbacks have different type signatures, but libev	5282	callback: The watcher callbacks have different type signatures, but libev
4507	calls them using an C<ev_watcher *> internally.	5283	calls them using an C<ev_watcher *> internally.
		5284
		5285	=item pointer accesses must be thread-atomic
		5286
		5287	Accessing a pointer value must be atomic, it must both be readable and
		5288	writable in one piece - this is the case on all current architectures.
4508		5289
4509	=item C<sig_atomic_t volatile> must be thread-atomic as well	5290	=item C<sig_atomic_t volatile> must be thread-atomic as well
4510		5291
4511	The type C<sig_atomic_t volatile> (or whatever is defined as	5292	The type C<sig_atomic_t volatile> (or whatever is defined as
4512	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different	5293	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different
…		…
4535	watchers.	5316	watchers.
4536		5317
4537	=item C<double> must hold a time value in seconds with enough accuracy	5318	=item C<double> must hold a time value in seconds with enough accuracy
4538		5319
4539	The type C<double> is used to represent timestamps. It is required to	5320	The type C<double> is used to represent timestamps. It is required to
4540	have at least 51 bits of mantissa (and 9 bits of exponent), which is good	5321	have at least 51 bits of mantissa (and 9 bits of exponent), which is
4541	enough for at least into the year 4000. This requirement is fulfilled by	5322	good enough for at least into the year 4000 with millisecond accuracy
		5323	(the design goal for libev). This requirement is overfulfilled by
4542	implementations implementing IEEE 754, which is basically all existing	5324	implementations using IEEE 754, which is basically all existing ones.
		5325
4543	ones. With IEEE 754 doubles, you get microsecond accuracy until at least	5326	With IEEE 754 doubles, you get microsecond accuracy until at least the
4544	2200.	5327	year 2255 (and millisecond accuracy till the year 287396 - by then, libev
		5328	is either obsolete or somebody patched it to use C<long double> or
		5329	something like that, just kidding).
4545		5330
4546	=back	5331	=back
4547		5332
4548	If you know of other additional requirements drop me a note.	5333	If you know of other additional requirements drop me a note.
4549		5334
…		…
4611	=item Processing ev_async_send: O(number_of_async_watchers)	5396	=item Processing ev_async_send: O(number_of_async_watchers)
4612		5397
4613	=item Processing signals: O(max_signal_number)	5398	=item Processing signals: O(max_signal_number)
4614		5399
4615	Sending involves a system call I<iff> there were no other C<ev_async_send>	5400	Sending involves a system call I<iff> there were no other C<ev_async_send>
4616	calls in the current loop iteration. Checking for async and signal events	5401	calls in the current loop iteration and the loop is currently
		5402	blocked. Checking for async and signal events involves iterating over all
4617	involves iterating over all running async watchers or all signal numbers.	5403	running async watchers or all signal numbers.
4618		5404
4619	=back	5405	=back
4620		5406
4621		5407
		5408	=head1 PORTING FROM LIBEV 3.X TO 4.X
		5409
		5410	The major version 4 introduced some incompatible changes to the API.
		5411
		5412	At the moment, the C<ev.h> header file provides compatibility definitions
		5413	for all changes, so most programs should still compile. The compatibility
		5414	layer might be removed in later versions of libev, so better update to the
		5415	new API early than late.
		5416
		5417	=over 4
		5418
		5419	=item C<EV_COMPAT3> backwards compatibility mechanism
		5420
		5421	The backward compatibility mechanism can be controlled by
		5422	C<EV_COMPAT3>. See L</PREPROCESSOR SYMBOLS/MACROS> in the L</EMBEDDING>
		5423	section.
		5424
		5425	=item C<ev_default_destroy> and C<ev_default_fork> have been removed
		5426
		5427	These calls can be replaced easily by their C<ev_loop_xxx> counterparts:
		5428
		5429	ev_loop_destroy (EV_DEFAULT_UC);
		5430	ev_loop_fork (EV_DEFAULT);
		5431
		5432	=item function/symbol renames
		5433
		5434	A number of functions and symbols have been renamed:
		5435
		5436	ev_loop => ev_run
		5437	EVLOOP_NONBLOCK => EVRUN_NOWAIT
		5438	EVLOOP_ONESHOT => EVRUN_ONCE
		5439
		5440	ev_unloop => ev_break
		5441	EVUNLOOP_CANCEL => EVBREAK_CANCEL
		5442	EVUNLOOP_ONE => EVBREAK_ONE
		5443	EVUNLOOP_ALL => EVBREAK_ALL
		5444
		5445	EV_TIMEOUT => EV_TIMER
		5446
		5447	ev_loop_count => ev_iteration
		5448	ev_loop_depth => ev_depth
		5449	ev_loop_verify => ev_verify
		5450
		5451	Most functions working on C<struct ev_loop> objects don't have an
		5452	C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and
		5453	associated constants have been renamed to not collide with the C<struct
		5454	ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme
		5455	as all other watcher types. Note that C<ev_loop_fork> is still called
		5456	C<ev_loop_fork> because it would otherwise clash with the C<ev_fork>
		5457	typedef.
		5458
		5459	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>
		5460
		5461	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different
		5462	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile
		5463	and work, but the library code will of course be larger.
		5464
		5465	=back
		5466
		5467
4622	=head1 GLOSSARY	5468	=head1 GLOSSARY
4623		5469
4624	=over 4	5470	=over 4
4625		5471
4626	=item active	5472	=item active
4627		5473
4628	A watcher is active as long as it has been started (has been attached to	5474	A watcher is active as long as it has been started and not yet stopped.
4629	an event loop) but not yet stopped (disassociated from the event loop).	5475	See L</WATCHER STATES> for details.
4630		5476
4631	=item application	5477	=item application
4632		5478
4633	In this document, an application is whatever is using libev.	5479	In this document, an application is whatever is using libev.
		5480
		5481	=item backend
		5482
		5483	The part of the code dealing with the operating system interfaces.
4634		5484
4635	=item callback	5485	=item callback
4636		5486
4637	The address of a function that is called when some event has been	5487	The address of a function that is called when some event has been
4638	detected. Callbacks are being passed the event loop, the watcher that	5488	detected. Callbacks are being passed the event loop, the watcher that
4639	received the event, and the actual event bitset.	5489	received the event, and the actual event bitset.
4640		5490
4641	=item callback invocation	5491	=item callback/watcher invocation
4642		5492
4643	The act of calling the callback associated with a watcher.	5493	The act of calling the callback associated with a watcher.
4644		5494
4645	=item event	5495	=item event
4646		5496
4647	A change of state of some external event, such as data now being available	5497	A change of state of some external event, such as data now being available
4648	for reading on a file descriptor, time having passed or simply not having	5498	for reading on a file descriptor, time having passed or simply not having
4649	any other events happening anymore.	5499	any other events happening anymore.
4650		5500
4651	In libev, events are represented as single bits (such as C<EV_READ> or	5501	In libev, events are represented as single bits (such as C<EV_READ> or
4652	C<EV_TIMEOUT>).	5502	C<EV_TIMER>).
4653		5503
4654	=item event library	5504	=item event library
4655		5505
4656	A software package implementing an event model and loop.	5506	A software package implementing an event model and loop.
4657		5507
…		…
4665	The model used to describe how an event loop handles and processes	5515	The model used to describe how an event loop handles and processes
4666	watchers and events.	5516	watchers and events.
4667		5517
4668	=item pending	5518	=item pending
4669		5519
4670	A watcher is pending as soon as the corresponding event has been detected,	5520	A watcher is pending as soon as the corresponding event has been
4671	and stops being pending as soon as the watcher will be invoked or its	5521	detected. See L</WATCHER STATES> for details.
4672	pending status is explicitly cleared by the application.
4673
4674	A watcher can be pending, but not active. Stopping a watcher also clears
4675	its pending status.
4676		5522
4677	=item real time	5523	=item real time
4678		5524
4679	The physical time that is observed. It is apparently strictly monotonic :)	5525	The physical time that is observed. It is apparently strictly monotonic :)
4680		5526
4681	=item wall-clock time	5527	=item wall-clock time
4682		5528
4683	The time and date as shown on clocks. Unlike real time, it can actually	5529	The time and date as shown on clocks. Unlike real time, it can actually
4684	be wrong and jump forwards and backwards, e.g. when the you adjust your	5530	be wrong and jump forwards and backwards, e.g. when you adjust your
4685	clock.	5531	clock.
4686		5532
4687	=item watcher	5533	=item watcher
4688		5534
4689	A data structure that describes interest in certain events. Watchers need	5535	A data structure that describes interest in certain events. Watchers need
4690	to be started (attached to an event loop) before they can receive events.	5536	to be started (attached to an event loop) before they can receive events.
4691		5537
4692	=item watcher invocation
4693
4694	The act of calling the callback associated with a watcher.
4695
4696	=back	5538	=back
4697		5539
4698	=head1 AUTHOR	5540	=head1 AUTHOR
4699		5541
4700	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson.	5542	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael
		5543	Magnusson and Emanuele Giaquinta, and minor corrections by many others.
4701		5544

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