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Revision 1.352 by root, Mon Jan 10 14:30:15 2011 UTC

…		…
26	puts ("stdin ready");	26	puts ("stdin ready");
27	// for one-shot events, one must manually stop the watcher	27	// for one-shot events, one must manually stop the watcher
28	// with its corresponding stop function.	28	// with its corresponding stop function.
29	ev_io_stop (EV_A_ w);	29	ev_io_stop (EV_A_ w);
30		30
31	// this causes all nested ev_loop's to stop iterating	31	// this causes all nested ev_run's to stop iterating
32	ev_unloop (EV_A_ EVUNLOOP_ALL);	32	ev_break (EV_A_ EVBREAK_ALL);
33	}	33	}
34		34
35	// another callback, this time for a time-out	35	// another callback, this time for a time-out
36	static void	36	static void
37	timeout_cb (EV_P_ ev_timer *w, int revents)	37	timeout_cb (EV_P_ ev_timer *w, int revents)
38	{	38	{
39	puts ("timeout");	39	puts ("timeout");
40	// this causes the innermost ev_loop to stop iterating	40	// this causes the innermost ev_run to stop iterating
41	ev_unloop (EV_A_ EVUNLOOP_ONE);	41	ev_break (EV_A_ EVBREAK_ONE);
42	}	42	}
43		43
44	int	44	int
45	main (void)	45	main (void)
46	{	46	{
47	// use the default event loop unless you have special needs	47	// use the default event loop unless you have special needs
48	struct ev_loop *loop = ev_default_loop (0);	48	struct ev_loop *loop = EV_DEFAULT;
49		49
50	// initialise an io watcher, then start it	50	// initialise an io watcher, then start it
51	// this one will watch for stdin to become readable	51	// this one will watch for stdin to become readable
52	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);	52	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);
53	ev_io_start (loop, &stdin_watcher);	53	ev_io_start (loop, &stdin_watcher);
…		…
56	// simple non-repeating 5.5 second timeout	56	// simple non-repeating 5.5 second timeout
57	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);	57	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
58	ev_timer_start (loop, &timeout_watcher);	58	ev_timer_start (loop, &timeout_watcher);
59		59
60	// now wait for events to arrive	60	// now wait for events to arrive
61	ev_loop (loop, 0);	61	ev_run (loop, 0);
62		62
63	// unloop was called, so exit	63	// unloop was called, so exit
64	return 0;	64	return 0;
65	}	65	}
66		66
…		…
75	While this document tries to be as complete as possible in documenting	75	While this document tries to be as complete as possible in documenting
76	libev, its usage and the rationale behind its design, it is not a tutorial	76	libev, its usage and the rationale behind its design, it is not a tutorial
77	on event-based programming, nor will it introduce event-based programming	77	on event-based programming, nor will it introduce event-based programming
78	with libev.	78	with libev.
79		79
80	Familarity with event based programming techniques in general is assumed	80	Familiarity with event based programming techniques in general is assumed
81	throughout this document.	81	throughout this document.
		82
		83	=head1 WHAT TO READ WHEN IN A HURRY
		84
		85	This manual tries to be very detailed, but unfortunately, this also makes
		86	it very long. If you just want to know the basics of libev, I suggest
		87	reading L<ANATOMY OF A WATCHER>, then the L<EXAMPLE PROGRAM> above and
		88	look up the missing functions in L<GLOBAL FUNCTIONS> and the C<ev_io> and
		89	C<ev_timer> sections in L<WATCHER TYPES>.
82		90
83	=head1 ABOUT LIBEV	91	=head1 ABOUT LIBEV
84		92
85	Libev is an event loop: you register interest in certain events (such as a	93	Libev is an event loop: you register interest in certain events (such as a
86	file descriptor being readable or a timeout occurring), and it will manage	94	file descriptor being readable or a timeout occurring), and it will manage
…		…
118	Libev is very configurable. In this manual the default (and most common)	126	Libev is very configurable. In this manual the default (and most common)
119	configuration will be described, which supports multiple event loops. For	127	configuration will be described, which supports multiple event loops. For
120	more info about various configuration options please have a look at	128	more info about various configuration options please have a look at
121	B<EMBED> section in this manual. If libev was configured without support	129	B<EMBED> section in this manual. If libev was configured without support
122	for multiple event loops, then all functions taking an initial argument of	130	for multiple event loops, then all functions taking an initial argument of
123	name C<loop> (which is always of type C<ev_loop *>) will not have	131	name C<loop> (which is always of type C<struct ev_loop *>) will not have
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_update_now> 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 until
174	either it is interrupted or the given time interval has passed. Basically	184	either it is interrupted or the given time interval has passed. Basically
…		…
191	as this indicates an incompatible change. Minor versions are usually	201	as this indicates an incompatible change. Minor versions are usually
192	compatible to older versions, so a larger minor version alone is usually	202	compatible to older versions, so a larger minor version alone is usually
193	not a problem.	203	not a problem.
194		204
195	Example: Make sure we haven't accidentally been linked against the wrong	205	Example: Make sure we haven't accidentally been linked against the wrong
196	version.	206	version (note, however, that this will not detect other ABI mismatches,
		207	such as LFS or reentrancy).
197		208
198	assert (("libev version mismatch",	209	assert (("libev version mismatch",
199	ev_version_major () == EV_VERSION_MAJOR	210	ev_version_major () == EV_VERSION_MAJOR
200	&& ev_version_minor () >= EV_VERSION_MINOR));	211	&& ev_version_minor () >= EV_VERSION_MINOR));
201		212
…		…
212	assert (("sorry, no epoll, no sex",	223	assert (("sorry, no epoll, no sex",
213	ev_supported_backends () & EVBACKEND_EPOLL));	224	ev_supported_backends () & EVBACKEND_EPOLL));
214		225
215	=item unsigned int ev_recommended_backends ()	226	=item unsigned int ev_recommended_backends ()
216		227
217	Return the set of all backends compiled into this binary of libev and also	228	Return the set of all backends compiled into this binary of libev and
218	recommended for this platform. This set is often smaller than the one	229	also recommended for this platform, meaning it will work for most file
		230	descriptor types. This set is often smaller than the one returned by
219	returned by C<ev_supported_backends>, as for example kqueue is broken on	231	C<ev_supported_backends>, as for example kqueue is broken on most BSDs
220	most BSDs and will not be auto-detected unless you explicitly request it	232	and will not be auto-detected unless you explicitly request it (assuming
221	(assuming you know what you are doing). This is the set of backends that	233	you know what you are doing). This is the set of backends that libev will
222	libev will probe for if you specify no backends explicitly.	234	probe for if you specify no backends explicitly.
223		235
224	=item unsigned int ev_embeddable_backends ()	236	=item unsigned int ev_embeddable_backends ()
225		237
226	Returns the set of backends that are embeddable in other event loops. This	238	Returns the set of backends that are embeddable in other event loops. This
227	is the theoretical, all-platform, value. To find which backends	239	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	240	current system. To find which embeddable backends might be supported on
229	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for	241	the current system, you would need to look at C<ev_embeddable_backends ()
230	recommended ones.	242	& ev_supported_backends ()>, likewise for recommended ones.
231		243
232	See the description of C<ev_embed> watchers for more info.	244	See the description of C<ev_embed> watchers for more info.
233		245
234	=item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT]	246	=item ev_set_allocator (void *(*cb)(void *ptr, long size))
235		247
236	Sets the allocation function to use (the prototype is similar - the	248	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	249	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	250	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	251	when memory needs to be allocated (C<size != 0>), the library might abort
…		…
265	}	277	}
266		278
267	...	279	...
268	ev_set_allocator (persistent_realloc);	280	ev_set_allocator (persistent_realloc);
269		281
270	=item ev_set_syserr_cb (void (*cb)(const char *msg)); [NOT REENTRANT]	282	=item ev_set_syserr_cb (void (*cb)(const char *msg))
271		283
272	Set the callback function to call on a retryable system call error (such	284	Set the callback function to call on a retryable system call error (such
273	as failed select, poll, epoll_wait). The message is a printable string	285	as failed select, poll, epoll_wait). The message is a printable string
274	indicating the system call or subsystem causing the problem. If this	286	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	287	callback is set, then libev will expect it to remedy the situation, no
…		…
287	}	299	}
288		300
289	...	301	...
290	ev_set_syserr_cb (fatal_error);	302	ev_set_syserr_cb (fatal_error);
291		303
		304	=item ev_feed_signal (int signum)
		305
		306	This function can be used to "simulate" a signal receive. It is completely
		307	safe to call this function at any time, from any context, including signal
		308	handlers or random threads.
		309
		310	Its main use is to customise signal handling in your process, especially
		311	in the presence of threads. For example, you could block signals
		312	by default in all threads (and specifying C<EVFLAG_NOSIGMASK> when
		313	creating any loops), and in one thread, use C<sigwait> or any other
		314	mechanism to wait for signals, then "deliver" them to libev by calling
		315	C<ev_feed_signal>.
		316
292	=back	317	=back
293		318
294	=head1 FUNCTIONS CONTROLLING THE EVENT LOOP	319	=head1 FUNCTIONS CONTROLLING EVENT LOOPS
295		320
296	An event loop is described by a C<struct ev_loop *> (the C<struct>	321	An event loop is described by a C<struct ev_loop *> (the C<struct> is
297	is I<not> optional in this case, as there is also an C<ev_loop>	322	I<not> optional in this case unless libev 3 compatibility is disabled, as
298	I<function>).	323	libev 3 had an C<ev_loop> function colliding with the struct name).
299		324
300	The library knows two types of such loops, the I<default> loop, which	325	The library knows two types of such loops, the I<default> loop, which
301	supports signals and child events, and dynamically created loops which do	326	supports child process events, and dynamically created event loops which
302	not.	327	do not.
303		328
304	=over 4	329	=over 4
305		330
306	=item struct ev_loop *ev_default_loop (unsigned int flags)	331	=item struct ev_loop *ev_default_loop (unsigned int flags)
307		332
308	This will initialise the default event loop if it hasn't been initialised	333	This returns the "default" event loop object, which is what you should
309	yet and return it. If the default loop could not be initialised, returns	334	normally use when you just need "the event loop". Event loop objects and
310	false. If it already was initialised it simply returns it (and ignores the	335	the C<flags> parameter are described in more detail in the entry for
311	flags. If that is troubling you, check C<ev_backend ()> afterwards).	336	C<ev_loop_new>.
		337
		338	If the default loop is already initialised then this function simply
		339	returns it (and ignores the flags. If that is troubling you, check
		340	C<ev_backend ()> afterwards). Otherwise it will create it with the given
		341	flags, which should almost always be C<0>, unless the caller is also the
		342	one calling C<ev_run> or otherwise qualifies as "the main program".
312		343
313	If you don't know what event loop to use, use the one returned from this	344	If you don't know what event loop to use, use the one returned from this
314	function.	345	function (or via the C<EV_DEFAULT> macro).
315		346
316	Note that this function is I<not> thread-safe, so if you want to use it	347	Note that this function is I<not> thread-safe, so if you want to use it
317	from multiple threads, you have to lock (note also that this is unlikely,	348	from multiple threads, you have to employ some kind of mutex (note also
318	as loops cannot be shared easily between threads anyway).	349	that this case is unlikely, as loops cannot be shared easily between
		350	threads anyway).
319		351
320	The default loop is the only loop that can handle C<ev_signal> and	352	The default loop is the only loop that can handle C<ev_child> watchers,
321	C<ev_child> watchers, and to do this, it always registers a handler	353	and to do this, it always registers a handler for C<SIGCHLD>. If this is
322	for C<SIGCHLD>. If this is a problem for your application you can either	354	a problem for your application you can either create a dynamic loop with
323	create a dynamic loop with C<ev_loop_new> that doesn't do that, or you	355	C<ev_loop_new> which doesn't do that, or you can simply overwrite the
324	can simply overwrite the C<SIGCHLD> signal handler I<after> calling	356	C<SIGCHLD> signal handler I<after> calling C<ev_default_init>.
325	C<ev_default_init>.	357
		358	Example: This is the most typical usage.
		359
		360	if (!ev_default_loop (0))
		361	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
		362
		363	Example: Restrict libev to the select and poll backends, and do not allow
		364	environment settings to be taken into account:
		365
		366	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
		367
		368	=item struct ev_loop *ev_loop_new (unsigned int flags)
		369
		370	This will create and initialise a new event loop object. If the loop
		371	could not be initialised, returns false.
		372
		373	This function is thread-safe, and one common way to use libev with
		374	threads is indeed to create one loop per thread, and using the default
		375	loop in the "main" or "initial" thread.
326		376
327	The flags argument can be used to specify special behaviour or specific	377	The flags argument can be used to specify special behaviour or specific
328	backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>).	378	backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>).
329		379
330	The following flags are supported:	380	The following flags are supported:
…		…
345	useful to try out specific backends to test their performance, or to work	395	useful to try out specific backends to test their performance, or to work
346	around bugs.	396	around bugs.
347		397
348	=item C<EVFLAG_FORKCHECK>	398	=item C<EVFLAG_FORKCHECK>
349		399
350	Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after	400	Instead of calling C<ev_loop_fork> manually after a fork, you can also
351	a fork, you can also make libev check for a fork in each iteration by	401	make libev check for a fork in each iteration by enabling this flag.
352	enabling this flag.
353		402
354	This works by calling C<getpid ()> on every iteration of the loop,	403	This works by calling C<getpid ()> on every iteration of the loop,
355	and thus this might slow down your event loop if you do a lot of loop	404	and thus this might slow down your event loop if you do a lot of loop
356	iterations and little real work, but is usually not noticeable (on my	405	iterations and little real work, but is usually not noticeable (on my
357	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence	406	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence
…		…
366	environment variable.	415	environment variable.
367		416
368	=item C<EVFLAG_NOINOTIFY>	417	=item C<EVFLAG_NOINOTIFY>
369		418
370	When this flag is specified, then libev will not attempt to use the	419	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	420	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	421	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.	422	otherwise each loop using C<ev_stat> watchers consumes one inotify handle.
374		423
375	=item C<EVFLAG_NOSIGFD>	424	=item C<EVFLAG_SIGNALFD>
376		425
377	When this flag is specified, then libev will not attempt to use the	426	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 is	427	I<signalfd> API for its C<ev_signal> (and C<ev_child>) watchers. This API
379	probably only useful to work around any bugs in libev. Consequently, this	428	delivers signals synchronously, which makes it both faster and might make
380	flag might go away once the signalfd functionality is considered stable,	429	it possible to get the queued signal data. It can also simplify signal
381	so it's useful mostly in environment variables and not in program code.	430	handling with threads, as long as you properly block signals in your
		431	threads that are not interested in handling them.
		432
		433	Signalfd will not be used by default as this changes your signal mask, and
		434	there are a lot of shoddy libraries and programs (glib's threadpool for
		435	example) that can't properly initialise their signal masks.
		436
		437	=item C<EVFLAG_NOSIGMASK>
		438
		439	When this flag is specified, then libev will avoid to modify the signal
		440	mask. Specifically, this means you ahve to make sure signals are unblocked
		441	when you want to receive them.
		442
		443	This behaviour is useful when you want to do your own signal handling, or
		444	want to handle signals only in specific threads and want to avoid libev
		445	unblocking the signals.
		446
		447	This flag's behaviour will become the default in future versions of libev.
382		448
383	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	449	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
384		450
385	This is your standard select(2) backend. Not I<completely> standard, as	451	This is your standard select(2) backend. Not I<completely> standard, as
386	libev tries to roll its own fd_set with no limits on the number of fds,	452	libev tries to roll its own fd_set with no limits on the number of fds,
…		…
422	epoll scales either O(1) or O(active_fds).	488	epoll scales either O(1) or O(active_fds).
423		489
424	The epoll mechanism deserves honorable mention as the most misdesigned	490	The epoll mechanism deserves honorable mention as the most misdesigned
425	of the more advanced event mechanisms: mere annoyances include silently	491	of the more advanced event mechanisms: mere annoyances include silently
426	dropping file descriptors, requiring a system call per change per file	492	dropping file descriptors, requiring a system call per change per file
427	descriptor (and unnecessary guessing of parameters), problems with dup and	493	descriptor (and unnecessary guessing of parameters), problems with dup,
		494	returning before the timeout value, resulting in additional iterations
		495	(and only giving 5ms accuracy while select on the same platform gives
428	so on. The biggest issue is fork races, however - if a program forks then	496	0.1ms) and so on. The biggest issue is fork races, however - if a program
429	I<both> parent and child process have to recreate the epoll set, which can	497	forks then I<both> parent and child process have to recreate the epoll
430	take considerable time (one syscall per file descriptor) and is of course	498	set, which can take considerable time (one syscall per file descriptor)
431	hard to detect.	499	and is of course hard to detect.
432		500
433	Epoll is also notoriously buggy - embedding epoll fds I<should> work, but	501	Epoll is also notoriously buggy - embedding epoll fds I<should> work, but
434	of course I<doesn't>, and epoll just loves to report events for totally	502	of course I<doesn't>, and epoll just loves to report events for totally
435	I<different> file descriptors (even already closed ones, so one cannot	503	I<different> file descriptors (even already closed ones, so one cannot
436	even remove them from the set) than registered in the set (especially	504	even remove them from the set) than registered in the set (especially
437	on SMP systems). Libev tries to counter these spurious notifications by	505	on SMP systems). Libev tries to counter these spurious notifications by
438	employing an additional generation counter and comparing that against the	506	employing an additional generation counter and comparing that against the
439	events to filter out spurious ones, recreating the set when required.	507	events to filter out spurious ones, recreating the set when required. Last
		508	not least, it also refuses to work with some file descriptors which work
		509	perfectly fine with C<select> (files, many character devices...).
		510
		511	Epoll is truly the train wreck analog among event poll mechanisms.
440		512
441	While stopping, setting and starting an I/O watcher in the same iteration	513	While stopping, setting and starting an I/O watcher in the same iteration
442	will result in some caching, there is still a system call per such	514	will result in some caching, there is still a system call per such
443	incident (because the same I<file descriptor> could point to a different	515	incident (because the same I<file descriptor> could point to a different
444	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed	516	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed
…		…
510	=item C<EVBACKEND_PORT> (value 32, Solaris 10)	582	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
511		583
512	This uses the Solaris 10 event port mechanism. As with everything on Solaris,	584	This uses the Solaris 10 event port mechanism. As with everything on Solaris,
513	it's really slow, but it still scales very well (O(active_fds)).	585	it's really slow, but it still scales very well (O(active_fds)).
514		586
515	Please note that Solaris event ports can deliver a lot of spurious
516	notifications, so you need to use non-blocking I/O or other means to avoid
517	blocking when no data (or space) is available.
518
519	While this backend scales well, it requires one system call per active	587	While this backend scales well, it requires one system call per active
520	file descriptor per loop iteration. For small and medium numbers of file	588	file descriptor per loop iteration. For small and medium numbers of file
521	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend	589	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend
522	might perform better.	590	might perform better.
523		591
524	On the positive side, with the exception of the spurious readiness	592	On the positive side, this backend actually performed fully to
525	notifications, this backend actually performed fully to specification
526	in all tests and is fully embeddable, which is a rare feat among the	593	specification in all tests and is fully embeddable, which is a rare feat
527	OS-specific backends (I vastly prefer correctness over speed hacks).	594	among the OS-specific backends (I vastly prefer correctness over speed
		595	hacks).
		596
		597	On the negative side, the interface is I<bizarre> - so bizarre that
		598	even sun itself gets it wrong in their code examples: The event polling
		599	function sometimes returning events to the caller even though an error
		600	occured, but with no indication whether it has done so or not (yes, it's
		601	even documented that way) - deadly for edge-triggered interfaces where
		602	you absolutely have to know whether an event occured or not because you
		603	have to re-arm the watcher.
		604
		605	Fortunately libev seems to be able to work around these idiocies.
528		606
529	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as	607	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as
530	C<EVBACKEND_POLL>.	608	C<EVBACKEND_POLL>.
531		609
532	=item C<EVBACKEND_ALL>	610	=item C<EVBACKEND_ALL>
533		611
534	Try all backends (even potentially broken ones that wouldn't be tried	612	Try all backends (even potentially broken ones that wouldn't be tried
535	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as	613	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as
536	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.	614	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.
537		615
538	It is definitely not recommended to use this flag.	616	It is definitely not recommended to use this flag, use whatever
		617	C<ev_recommended_backends ()> returns, or simply do not specify a backend
		618	at all.
		619
		620	=item C<EVBACKEND_MASK>
		621
		622	Not a backend at all, but a mask to select all backend bits from a
		623	C<flags> value, in case you want to mask out any backends from a flags
		624	value (e.g. when modifying the C<LIBEV_FLAGS> environment variable).
539		625
540	=back	626	=back
541		627
542	If one or more of the backend flags are or'ed into the flags value,	628	If one or more of the backend flags are or'ed into the flags value,
543	then only these backends will be tried (in the reverse order as listed	629	then only these backends will be tried (in the reverse order as listed
544	here). If none are specified, all backends in C<ev_recommended_backends	630	here). If none are specified, all backends in C<ev_recommended_backends
545	()> will be tried.	631	()> will be tried.
546		632
547	Example: This is the most typical usage.
548
549	if (!ev_default_loop (0))
550	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
551
552	Example: Restrict libev to the select and poll backends, and do not allow
553	environment settings to be taken into account:
554
555	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
556
557	Example: Use whatever libev has to offer, but make sure that kqueue is
558	used if available (warning, breaks stuff, best use only with your own
559	private event loop and only if you know the OS supports your types of
560	fds):
561
562	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
563
564	=item struct ev_loop *ev_loop_new (unsigned int flags)
565
566	Similar to C<ev_default_loop>, but always creates a new event loop that is
567	always distinct from the default loop. Unlike the default loop, it cannot
568	handle signal and child watchers, and attempts to do so will be greeted by
569	undefined behaviour (or a failed assertion if assertions are enabled).
570
571	Note that this function I<is> thread-safe, and the recommended way to use
572	libev with threads is indeed to create one loop per thread, and using the
573	default loop in the "main" or "initial" thread.
574
575	Example: Try to create a event loop that uses epoll and nothing else.	633	Example: Try to create a event loop that uses epoll and nothing else.
576		634
577	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	635	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
578	if (!epoller)	636	if (!epoller)
579	fatal ("no epoll found here, maybe it hides under your chair");	637	fatal ("no epoll found here, maybe it hides under your chair");
580		638
		639	Example: Use whatever libev has to offer, but make sure that kqueue is
		640	used if available.
		641
		642	struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE);
		643
581	=item ev_default_destroy ()	644	=item ev_loop_destroy (loop)
582		645
583	Destroys the default loop again (frees all memory and kernel state	646	Destroys an event loop object (frees all memory and kernel state
584	etc.). None of the active event watchers will be stopped in the normal	647	etc.). None of the active event watchers will be stopped in the normal
585	sense, so e.g. C<ev_is_active> might still return true. It is your	648	sense, so e.g. C<ev_is_active> might still return true. It is your
586	responsibility to either stop all watchers cleanly yourself I<before>	649	responsibility to either stop all watchers cleanly yourself I<before>
587	calling this function, or cope with the fact afterwards (which is usually	650	calling this function, or cope with the fact afterwards (which is usually
588	the easiest thing, you can just ignore the watchers and/or C<free ()> them	651	the easiest thing, you can just ignore the watchers and/or C<free ()> them
…		…
590		653
591	Note that certain global state, such as signal state (and installed signal	654	Note that certain global state, such as signal state (and installed signal
592	handlers), will not be freed by this function, and related watchers (such	655	handlers), will not be freed by this function, and related watchers (such
593	as signal and child watchers) would need to be stopped manually.	656	as signal and child watchers) would need to be stopped manually.
594		657
595	In general it is not advisable to call this function except in the	658	This function is normally used on loop objects allocated by
596	rare occasion where you really need to free e.g. the signal handling	659	C<ev_loop_new>, but it can also be used on the default loop returned by
		660	C<ev_default_loop>, in which case it is not thread-safe.
		661
		662	Note that it is not advisable to call this function on the default loop
		663	except in the rare occasion where you really need to free its resources.
597	pipe fds. If you need dynamically allocated loops it is better to use	664	If you need dynamically allocated loops it is better to use C<ev_loop_new>
598	C<ev_loop_new> and C<ev_loop_destroy>.	665	and C<ev_loop_destroy>.
599		666
600	=item ev_loop_destroy (loop)	667	=item ev_loop_fork (loop)
601		668
602	Like C<ev_default_destroy>, but destroys an event loop created by an
603	earlier call to C<ev_loop_new>.
604
605	=item ev_default_fork ()
606
607	This function sets a flag that causes subsequent C<ev_loop> iterations	669	This function sets a flag that causes subsequent C<ev_run> iterations to
608	to reinitialise the kernel state for backends that have one. Despite the	670	reinitialise the kernel state for backends that have one. Despite the
609	name, you can call it anytime, but it makes most sense after forking, in	671	name, you can call it anytime, but it makes most sense after forking, in
610	the child process (or both child and parent, but that again makes little	672	the child process. You I<must> call it (or use C<EVFLAG_FORKCHECK>) in the
611	sense). You I<must> call it in the child before using any of the libev	673	child before resuming or calling C<ev_run>.
612	functions, and it will only take effect at the next C<ev_loop> iteration.	674
		675	Again, you I<have> to call it on I<any> loop that you want to re-use after
		676	a fork, I<even if you do not plan to use the loop in the parent>. This is
		677	because some kernel interfaces *cough* I<kqueue> *cough* do funny things
		678	during fork.
613		679
614	On the other hand, you only need to call this function in the child	680	On the other hand, you only need to call this function in the child
615	process if and only if you want to use the event library in the child. If	681	process if and only if you want to use the event loop in the child. If
616	you just fork+exec, you don't have to call it at all.	682	you just fork+exec or create a new loop in the child, you don't have to
		683	call it at all (in fact, C<epoll> is so badly broken that it makes a
		684	difference, but libev will usually detect this case on its own and do a
		685	costly reset of the backend).
617		686
618	The function itself is quite fast and it's usually not a problem to call	687	The function itself is quite fast and it's usually not a problem to call
619	it just in case after a fork. To make this easy, the function will fit in	688	it just in case after a fork.
620	quite nicely into a call to C<pthread_atfork>:
621		689
		690	Example: Automate calling C<ev_loop_fork> on the default loop when
		691	using pthreads.
		692
		693	static void
		694	post_fork_child (void)
		695	{
		696	ev_loop_fork (EV_DEFAULT);
		697	}
		698
		699	...
622	pthread_atfork (0, 0, ev_default_fork);	700	pthread_atfork (0, 0, post_fork_child);
623
624	=item ev_loop_fork (loop)
625
626	Like C<ev_default_fork>, but acts on an event loop created by
627	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
628	after fork that you want to re-use in the child, and how you do this is
629	entirely your own problem.
630		701
631	=item int ev_is_default_loop (loop)	702	=item int ev_is_default_loop (loop)
632		703
633	Returns true when the given loop is, in fact, the default loop, and false	704	Returns true when the given loop is, in fact, the default loop, and false
634	otherwise.	705	otherwise.
635		706
636	=item unsigned int ev_loop_count (loop)	707	=item unsigned int ev_iteration (loop)
637		708
638	Returns the count of loop iterations for the loop, which is identical to	709	Returns the current iteration count for the event loop, which is identical
639	the number of times libev did poll for new events. It starts at C<0> and	710	to the number of times libev did poll for new events. It starts at C<0>
640	happily wraps around with enough iterations.	711	and happily wraps around with enough iterations.
641		712
642	This value can sometimes be useful as a generation counter of sorts (it	713	This value can sometimes be useful as a generation counter of sorts (it
643	"ticks" the number of loop iterations), as it roughly corresponds with	714	"ticks" the number of loop iterations), as it roughly corresponds with
644	C<ev_prepare> and C<ev_check> calls.	715	C<ev_prepare> and C<ev_check> calls - and is incremented between the
		716	prepare and check phases.
645		717
646	=item unsigned int ev_loop_depth (loop)	718	=item unsigned int ev_depth (loop)
647		719
648	Returns the number of times C<ev_loop> was entered minus the number of	720	Returns the number of times C<ev_run> was entered minus the number of
649	times C<ev_loop> was exited, in other words, the recursion depth.	721	times C<ev_run> was exited normally, in other words, the recursion depth.
650		722
651	Outside C<ev_loop>, this number is zero. In a callback, this number is	723	Outside C<ev_run>, this number is zero. In a callback, this number is
652	C<1>, unless C<ev_loop> was invoked recursively (or from another thread),	724	C<1>, unless C<ev_run> was invoked recursively (or from another thread),
653	in which case it is higher.	725	in which case it is higher.
654		726
655	Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread	727	Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread,
656	etc.), doesn't count as exit.	728	throwing an exception etc.), doesn't count as "exit" - consider this
		729	as a hint to avoid such ungentleman-like behaviour unless it's really
		730	convenient, in which case it is fully supported.
657		731
658	=item unsigned int ev_backend (loop)	732	=item unsigned int ev_backend (loop)
659		733
660	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	734	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
661	use.	735	use.
…		…
670		744
671	=item ev_now_update (loop)	745	=item ev_now_update (loop)
672		746
673	Establishes the current time by querying the kernel, updating the time	747	Establishes the current time by querying the kernel, updating the time
674	returned by C<ev_now ()> in the progress. This is a costly operation and	748	returned by C<ev_now ()> in the progress. This is a costly operation and
675	is usually done automatically within C<ev_loop ()>.	749	is usually done automatically within C<ev_run ()>.
676		750
677	This function is rarely useful, but when some event callback runs for a	751	This function is rarely useful, but when some event callback runs for a
678	very long time without entering the event loop, updating libev's idea of	752	very long time without entering the event loop, updating libev's idea of
679	the current time is a good idea.	753	the current time is a good idea.
680		754
…		…
682		756
683	=item ev_suspend (loop)	757	=item ev_suspend (loop)
684		758
685	=item ev_resume (loop)	759	=item ev_resume (loop)
686		760
687	These two functions suspend and resume a loop, for use when the loop is	761	These two functions suspend and resume an event loop, for use when the
688	not used for a while and timeouts should not be processed.	762	loop is not used for a while and timeouts should not be processed.
689		763
690	A typical use case would be an interactive program such as a game: When	764	A typical use case would be an interactive program such as a game: When
691	the user presses C<^Z> to suspend the game and resumes it an hour later it	765	the user presses C<^Z> to suspend the game and resumes it an hour later it
692	would be best to handle timeouts as if no time had actually passed while	766	would be best to handle timeouts as if no time had actually passed while
693	the program was suspended. This can be achieved by calling C<ev_suspend>	767	the program was suspended. This can be achieved by calling C<ev_suspend>
…		…
695	C<ev_resume> directly afterwards to resume timer processing.	769	C<ev_resume> directly afterwards to resume timer processing.
696		770
697	Effectively, all C<ev_timer> watchers will be delayed by the time spend	771	Effectively, all C<ev_timer> watchers will be delayed by the time spend
698	between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers	772	between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers
699	will be rescheduled (that is, they will lose any events that would have	773	will be rescheduled (that is, they will lose any events that would have
700	occured while suspended).	774	occurred while suspended).
701		775
702	After calling C<ev_suspend> you B<must not> call I<any> function on the	776	After calling C<ev_suspend> you B<must not> call I<any> function on the
703	given loop other than C<ev_resume>, and you B<must not> call C<ev_resume>	777	given loop other than C<ev_resume>, and you B<must not> call C<ev_resume>
704	without a previous call to C<ev_suspend>.	778	without a previous call to C<ev_suspend>.
705		779
706	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the	780	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the
707	event loop time (see C<ev_now_update>).	781	event loop time (see C<ev_now_update>).
708		782
709	=item ev_loop (loop, int flags)	783	=item ev_run (loop, int flags)
710		784
711	Finally, this is it, the event handler. This function usually is called	785	Finally, this is it, the event handler. This function usually is called
712	after you have initialised all your watchers and you want to start	786	after you have initialised all your watchers and you want to start
713	handling events.	787	handling events. It will ask the operating system for any new events, call
		788	the watcher callbacks, an then repeat the whole process indefinitely: This
		789	is why event loops are called I<loops>.
714		790
715	If the flags argument is specified as C<0>, it will not return until	791	If the flags argument is specified as C<0>, it will keep handling events
716	either no event watchers are active anymore or C<ev_unloop> was called.	792	until either no event watchers are active anymore or C<ev_break> was
		793	called.
717		794
718	Please note that an explicit C<ev_unloop> is usually better than	795	Please note that an explicit C<ev_break> is usually better than
719	relying on all watchers to be stopped when deciding when a program has	796	relying on all watchers to be stopped when deciding when a program has
720	finished (especially in interactive programs), but having a program	797	finished (especially in interactive programs), but having a program
721	that automatically loops as long as it has to and no longer by virtue	798	that automatically loops as long as it has to and no longer by virtue
722	of relying on its watchers stopping correctly, that is truly a thing of	799	of relying on its watchers stopping correctly, that is truly a thing of
723	beauty.	800	beauty.
724		801
		802	This function is also I<mostly> exception-safe - you can break out of
		803	a C<ev_run> call by calling C<longjmp> in a callback, throwing a C++
		804	exception and so on. This does not decrement the C<ev_depth> value, nor
		805	will it clear any outstanding C<EVBREAK_ONE> breaks.
		806
725	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle	807	A flags value of C<EVRUN_NOWAIT> will look for new events, will handle
726	those events and any already outstanding ones, but will not block your	808	those events and any already outstanding ones, but will not wait and
727	process in case there are no events and will return after one iteration of	809	block your process in case there are no events and will return after one
728	the loop.	810	iteration of the loop. This is sometimes useful to poll and handle new
		811	events while doing lengthy calculations, to keep the program responsive.
729		812
730	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if	813	A flags value of C<EVRUN_ONCE> will look for new events (waiting if
731	necessary) and will handle those and any already outstanding ones. It	814	necessary) and will handle those and any already outstanding ones. It
732	will block your process until at least one new event arrives (which could	815	will block your process until at least one new event arrives (which could
733	be an event internal to libev itself, so there is no guarantee that a	816	be an event internal to libev itself, so there is no guarantee that a
734	user-registered callback will be called), and will return after one	817	user-registered callback will be called), and will return after one
735	iteration of the loop.	818	iteration of the loop.
736		819
737	This is useful if you are waiting for some external event in conjunction	820	This is useful if you are waiting for some external event in conjunction
738	with something not expressible using other libev watchers (i.e. "roll your	821	with something not expressible using other libev watchers (i.e. "roll your
739	own C<ev_loop>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is	822	own C<ev_run>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is
740	usually a better approach for this kind of thing.	823	usually a better approach for this kind of thing.
741		824
742	Here are the gory details of what C<ev_loop> does:	825	Here are the gory details of what C<ev_run> does:
743		826
		827	- Increment loop depth.
		828	- Reset the ev_break status.
744	- Before the first iteration, call any pending watchers.	829	- Before the first iteration, call any pending watchers.
		830	LOOP:
745	* If EVFLAG_FORKCHECK was used, check for a fork.	831	- If EVFLAG_FORKCHECK was used, check for a fork.
746	- If a fork was detected (by any means), queue and call all fork watchers.	832	- If a fork was detected (by any means), queue and call all fork watchers.
747	- Queue and call all prepare watchers.	833	- Queue and call all prepare watchers.
		834	- If ev_break was called, goto FINISH.
748	- If we have been forked, detach and recreate the kernel state	835	- If we have been forked, detach and recreate the kernel state
749	as to not disturb the other process.	836	as to not disturb the other process.
750	- Update the kernel state with all outstanding changes.	837	- Update the kernel state with all outstanding changes.
751	- Update the "event loop time" (ev_now ()).	838	- Update the "event loop time" (ev_now ()).
752	- Calculate for how long to sleep or block, if at all	839	- Calculate for how long to sleep or block, if at all
753	(active idle watchers, EVLOOP_NONBLOCK or not having	840	(active idle watchers, EVRUN_NOWAIT or not having
754	any active watchers at all will result in not sleeping).	841	any active watchers at all will result in not sleeping).
755	- Sleep if the I/O and timer collect interval say so.	842	- Sleep if the I/O and timer collect interval say so.
		843	- Increment loop iteration counter.
756	- Block the process, waiting for any events.	844	- Block the process, waiting for any events.
757	- Queue all outstanding I/O (fd) events.	845	- Queue all outstanding I/O (fd) events.
758	- Update the "event loop time" (ev_now ()), and do time jump adjustments.	846	- Update the "event loop time" (ev_now ()), and do time jump adjustments.
759	- Queue all expired timers.	847	- Queue all expired timers.
760	- Queue all expired periodics.	848	- Queue all expired periodics.
761	- Unless any events are pending now, queue all idle watchers.	849	- Queue all idle watchers with priority higher than that of pending events.
762	- Queue all check watchers.	850	- Queue all check watchers.
763	- Call all queued watchers in reverse order (i.e. check watchers first).	851	- Call all queued watchers in reverse order (i.e. check watchers first).
764	Signals and child watchers are implemented as I/O watchers, and will	852	Signals and child watchers are implemented as I/O watchers, and will
765	be handled here by queueing them when their watcher gets executed.	853	be handled here by queueing them when their watcher gets executed.
766	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	854	- If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT
767	were used, or there are no active watchers, return, otherwise	855	were used, or there are no active watchers, goto FINISH, otherwise
768	continue with step *.	856	continue with step LOOP.
		857	FINISH:
		858	- Reset the ev_break status iff it was EVBREAK_ONE.
		859	- Decrement the loop depth.
		860	- Return.
769		861
770	Example: Queue some jobs and then loop until no events are outstanding	862	Example: Queue some jobs and then loop until no events are outstanding
771	anymore.	863	anymore.
772		864
773	... queue jobs here, make sure they register event watchers as long	865	... queue jobs here, make sure they register event watchers as long
774	... as they still have work to do (even an idle watcher will do..)	866	... as they still have work to do (even an idle watcher will do..)
775	ev_loop (my_loop, 0);	867	ev_run (my_loop, 0);
776	... jobs done or somebody called unloop. yeah!	868	... jobs done or somebody called unloop. yeah!
777		869
778	=item ev_unloop (loop, how)	870	=item ev_break (loop, how)
779		871
780	Can be used to make a call to C<ev_loop> return early (but only after it	872	Can be used to make a call to C<ev_run> return early (but only after it
781	has processed all outstanding events). The C<how> argument must be either	873	has processed all outstanding events). The C<how> argument must be either
782	C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or	874	C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or
783	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.	875	C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return.
784		876
785	This "unloop state" will be cleared when entering C<ev_loop> again.	877	This "break state" will be cleared on the next call to C<ev_run>.
786		878
787	It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls.	879	It is safe to call C<ev_break> from outside any C<ev_run> calls, too, in
		880	which case it will have no effect.
788		881
789	=item ev_ref (loop)	882	=item ev_ref (loop)
790		883
791	=item ev_unref (loop)	884	=item ev_unref (loop)
792		885
793	Ref/unref can be used to add or remove a reference count on the event	886	Ref/unref can be used to add or remove a reference count on the event
794	loop: Every watcher keeps one reference, and as long as the reference	887	loop: Every watcher keeps one reference, and as long as the reference
795	count is nonzero, C<ev_loop> will not return on its own.	888	count is nonzero, C<ev_run> will not return on its own.
796		889
797	If you have a watcher you never unregister that should not keep C<ev_loop>	890	This is useful when you have a watcher that you never intend to
798	from returning, call ev_unref() after starting, and ev_ref() before	891	unregister, but that nevertheless should not keep C<ev_run> from
		892	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>
799	stopping it.	893	before stopping it.
800		894
801	As an example, libev itself uses this for its internal signal pipe: It	895	As an example, libev itself uses this for its internal signal pipe: It
802	is not visible to the libev user and should not keep C<ev_loop> from	896	is not visible to the libev user and should not keep C<ev_run> from
803	exiting if no event watchers registered by it are active. It is also an	897	exiting if no event watchers registered by it are active. It is also an
804	excellent way to do this for generic recurring timers or from within	898	excellent way to do this for generic recurring timers or from within
805	third-party libraries. Just remember to I<unref after start> and I<ref	899	third-party libraries. Just remember to I<unref after start> and I<ref
806	before stop> (but only if the watcher wasn't active before, or was active	900	before stop> (but only if the watcher wasn't active before, or was active
807	before, respectively. Note also that libev might stop watchers itself	901	before, respectively. Note also that libev might stop watchers itself
808	(e.g. non-repeating timers) in which case you have to C<ev_ref>	902	(e.g. non-repeating timers) in which case you have to C<ev_ref>
809	in the callback).	903	in the callback).
810		904
811	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	905	Example: Create a signal watcher, but keep it from keeping C<ev_run>
812	running when nothing else is active.	906	running when nothing else is active.
813		907
814	ev_signal exitsig;	908	ev_signal exitsig;
815	ev_signal_init (&exitsig, sig_cb, SIGINT);	909	ev_signal_init (&exitsig, sig_cb, SIGINT);
816	ev_signal_start (loop, &exitsig);	910	ev_signal_start (loop, &exitsig);
817	evf_unref (loop);	911	ev_unref (loop);
818		912
819	Example: For some weird reason, unregister the above signal handler again.	913	Example: For some weird reason, unregister the above signal handler again.
820		914
821	ev_ref (loop);	915	ev_ref (loop);
822	ev_signal_stop (loop, &exitsig);	916	ev_signal_stop (loop, &exitsig);
…		…
861	usually doesn't make much sense to set it to a lower value than C<0.01>,	955	usually doesn't make much sense to set it to a lower value than C<0.01>,
862	as this approaches the timing granularity of most systems. Note that if	956	as this approaches the timing granularity of most systems. Note that if
863	you do transactions with the outside world and you can't increase the	957	you do transactions with the outside world and you can't increase the
864	parallelity, then this setting will limit your transaction rate (if you	958	parallelity, then this setting will limit your transaction rate (if you
865	need to poll once per transaction and the I/O collect interval is 0.01,	959	need to poll once per transaction and the I/O collect interval is 0.01,
866	then you can't do more than 100 transations per second).	960	then you can't do more than 100 transactions per second).
867		961
868	Setting the I<timeout collect interval> can improve the opportunity for	962	Setting the I<timeout collect interval> can improve the opportunity for
869	saving power, as the program will "bundle" timer callback invocations that	963	saving power, as the program will "bundle" timer callback invocations that
870	are "near" in time together, by delaying some, thus reducing the number of	964	are "near" in time together, by delaying some, thus reducing the number of
871	times the process sleeps and wakes up again. Another useful technique to	965	times the process sleeps and wakes up again. Another useful technique to
…		…
879	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);	973	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);
880		974
881	=item ev_invoke_pending (loop)	975	=item ev_invoke_pending (loop)
882		976
883	This call will simply invoke all pending watchers while resetting their	977	This call will simply invoke all pending watchers while resetting their
884	pending state. Normally, C<ev_loop> does this automatically when required,	978	pending state. Normally, C<ev_run> does this automatically when required,
885	but when overriding the invoke callback this call comes handy.	979	but when overriding the invoke callback this call comes handy. This
		980	function can be invoked from a watcher - this can be useful for example
		981	when you want to do some lengthy calculation and want to pass further
		982	event handling to another thread (you still have to make sure only one
		983	thread executes within C<ev_invoke_pending> or C<ev_run> of course).
886		984
887	=item int ev_pending_count (loop)	985	=item int ev_pending_count (loop)
888		986
889	Returns the number of pending watchers - zero indicates that no watchers	987	Returns the number of pending watchers - zero indicates that no watchers
890	are pending.	988	are pending.
891		989
892	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))	990	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))
893		991
894	This overrides the invoke pending functionality of the loop: Instead of	992	This overrides the invoke pending functionality of the loop: Instead of
895	invoking all pending watchers when there are any, C<ev_loop> will call	993	invoking all pending watchers when there are any, C<ev_run> will call
896	this callback instead. This is useful, for example, when you want to	994	this callback instead. This is useful, for example, when you want to
897	invoke the actual watchers inside another context (another thread etc.).	995	invoke the actual watchers inside another context (another thread etc.).
898		996
899	If you want to reset the callback, use C<ev_invoke_pending> as new	997	If you want to reset the callback, use C<ev_invoke_pending> as new
900	callback.	998	callback.
…		…
903		1001
904	Sometimes you want to share the same loop between multiple threads. This	1002	Sometimes you want to share the same loop between multiple threads. This
905	can be done relatively simply by putting mutex_lock/unlock calls around	1003	can be done relatively simply by putting mutex_lock/unlock calls around
906	each call to a libev function.	1004	each call to a libev function.
907		1005
908	However, C<ev_loop> can run an indefinite time, so it is not feasible to	1006	However, C<ev_run> can run an indefinite time, so it is not feasible
909	wait for it to return. One way around this is to wake up the loop via	1007	to wait for it to return. One way around this is to wake up the event
910	C<ev_unloop> and C<av_async_send>, another way is to set these I<release>	1008	loop via C<ev_break> and C<av_async_send>, another way is to set these
911	and I<acquire> callbacks on the loop.	1009	I<release> and I<acquire> callbacks on the loop.
912		1010
913	When set, then C<release> will be called just before the thread is	1011	When set, then C<release> will be called just before the thread is
914	suspended waiting for new events, and C<acquire> is called just	1012	suspended waiting for new events, and C<acquire> is called just
915	afterwards.	1013	afterwards.
916		1014
…		…
919		1017
920	While event loop modifications are allowed between invocations of	1018	While event loop modifications are allowed between invocations of
921	C<release> and C<acquire> (that's their only purpose after all), no	1019	C<release> and C<acquire> (that's their only purpose after all), no
922	modifications done will affect the event loop, i.e. adding watchers will	1020	modifications done will affect the event loop, i.e. adding watchers will
923	have no effect on the set of file descriptors being watched, or the time	1021	have no effect on the set of file descriptors being watched, or the time
924	waited. USe an C<ev_async> watcher to wake up C<ev_loop> when you want it	1022	waited. Use an C<ev_async> watcher to wake up C<ev_run> when you want it
925	to take note of any changes you made.	1023	to take note of any changes you made.
926		1024
927	In theory, threads executing C<ev_loop> will be async-cancel safe between	1025	In theory, threads executing C<ev_run> will be async-cancel safe between
928	invocations of C<release> and C<acquire>.	1026	invocations of C<release> and C<acquire>.
929		1027
930	See also the locking example in the C<THREADS> section later in this	1028	See also the locking example in the C<THREADS> section later in this
931	document.	1029	document.
932		1030
933	=item ev_set_userdata (loop, void *data)	1031	=item ev_set_userdata (loop, void *data)
934		1032
935	=item ev_userdata (loop)	1033	=item void *ev_userdata (loop)
936		1034
937	Set and retrieve a single C<void *> associated with a loop. When	1035	Set and retrieve a single C<void *> associated with a loop. When
938	C<ev_set_userdata> has never been called, then C<ev_userdata> returns	1036	C<ev_set_userdata> has never been called, then C<ev_userdata> returns
939	C<0.>	1037	C<0>.
940		1038
941	These two functions can be used to associate arbitrary data with a loop,	1039	These two functions can be used to associate arbitrary data with a loop,
942	and are intended solely for the C<invoke_pending_cb>, C<release> and	1040	and are intended solely for the C<invoke_pending_cb>, C<release> and
943	C<acquire> callbacks described above, but of course can be (ab-)used for	1041	C<acquire> callbacks described above, but of course can be (ab-)used for
944	any other purpose as well.	1042	any other purpose as well.
945		1043
946	=item ev_loop_verify (loop)	1044	=item ev_verify (loop)
947		1045
948	This function only does something when C<EV_VERIFY> support has been	1046	This function only does something when C<EV_VERIFY> support has been
949	compiled in, which is the default for non-minimal builds. It tries to go	1047	compiled in, which is the default for non-minimal builds. It tries to go
950	through all internal structures and checks them for validity. If anything	1048	through all internal structures and checks them for validity. If anything
951	is found to be inconsistent, it will print an error message to standard	1049	is found to be inconsistent, it will print an error message to standard
…		…
962		1060
963	In the following description, uppercase C<TYPE> in names stands for the	1061	In the following description, uppercase C<TYPE> in names stands for the
964	watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer	1062	watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer
965	watchers and C<ev_io_start> for I/O watchers.	1063	watchers and C<ev_io_start> for I/O watchers.
966		1064
967	A watcher is a structure that you create and register to record your	1065	A watcher is an opaque structure that you allocate and register to record
968	interest in some event. For instance, if you want to wait for STDIN to	1066	your interest in some event. To make a concrete example, imagine you want
969	become readable, you would create an C<ev_io> watcher for that:	1067	to wait for STDIN to become readable, you would create an C<ev_io> watcher
		1068	for that:
970		1069
971	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)	1070	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)
972	{	1071	{
973	ev_io_stop (w);	1072	ev_io_stop (w);
974	ev_unloop (loop, EVUNLOOP_ALL);	1073	ev_break (loop, EVBREAK_ALL);
975	}	1074	}
976		1075
977	struct ev_loop *loop = ev_default_loop (0);	1076	struct ev_loop *loop = ev_default_loop (0);
978		1077
979	ev_io stdin_watcher;	1078	ev_io stdin_watcher;
980		1079
981	ev_init (&stdin_watcher, my_cb);	1080	ev_init (&stdin_watcher, my_cb);
982	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	1081	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
983	ev_io_start (loop, &stdin_watcher);	1082	ev_io_start (loop, &stdin_watcher);
984		1083
985	ev_loop (loop, 0);	1084	ev_run (loop, 0);
986		1085
987	As you can see, you are responsible for allocating the memory for your	1086	As you can see, you are responsible for allocating the memory for your
988	watcher structures (and it is I<usually> a bad idea to do this on the	1087	watcher structures (and it is I<usually> a bad idea to do this on the
989	stack).	1088	stack).
990		1089
991	Each watcher has an associated watcher structure (called C<struct ev_TYPE>	1090	Each watcher has an associated watcher structure (called C<struct ev_TYPE>
992	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).	1091	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).
993		1092
994	Each watcher structure must be initialised by a call to C<ev_init	1093	Each watcher structure must be initialised by a call to C<ev_init (watcher
995	(watcher *, callback)>, which expects a callback to be provided. This	1094	*, callback)>, which expects a callback to be provided. This callback is
996	callback gets invoked each time the event occurs (or, in the case of I/O	1095	invoked each time the event occurs (or, in the case of I/O watchers, each
997	watchers, each time the event loop detects that the file descriptor given	1096	time the event loop detects that the file descriptor given is readable
998	is readable and/or writable).	1097	and/or writable).
999		1098
1000	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>	1099	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>
1001	macro to configure it, with arguments specific to the watcher type. There	1100	macro to configure it, with arguments specific to the watcher type. There
1002	is also a macro to combine initialisation and setting in one call: C<<	1101	is also a macro to combine initialisation and setting in one call: C<<
1003	ev_TYPE_init (watcher *, callback, ...) >>.	1102	ev_TYPE_init (watcher *, callback, ...) >>.
…		…
1026	=item C<EV_WRITE>	1125	=item C<EV_WRITE>
1027		1126
1028	The file descriptor in the C<ev_io> watcher has become readable and/or	1127	The file descriptor in the C<ev_io> watcher has become readable and/or
1029	writable.	1128	writable.
1030		1129
1031	=item C<EV_TIMEOUT>	1130	=item C<EV_TIMER>
1032		1131
1033	The C<ev_timer> watcher has timed out.	1132	The C<ev_timer> watcher has timed out.
1034		1133
1035	=item C<EV_PERIODIC>	1134	=item C<EV_PERIODIC>
1036		1135
…		…
1054		1153
1055	=item C<EV_PREPARE>	1154	=item C<EV_PREPARE>
1056		1155
1057	=item C<EV_CHECK>	1156	=item C<EV_CHECK>
1058		1157
1059	All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts	1158	All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts
1060	to gather new events, and all C<ev_check> watchers are invoked just after	1159	to gather new events, and all C<ev_check> watchers are invoked just after
1061	C<ev_loop> has gathered them, but before it invokes any callbacks for any	1160	C<ev_run> has gathered them, but before it invokes any callbacks for any
1062	received events. Callbacks of both watcher types can start and stop as	1161	received events. Callbacks of both watcher types can start and stop as
1063	many watchers as they want, and all of them will be taken into account	1162	many watchers as they want, and all of them will be taken into account
1064	(for example, a C<ev_prepare> watcher might start an idle watcher to keep	1163	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
1065	C<ev_loop> from blocking).	1164	C<ev_run> from blocking).
1066		1165
1067	=item C<EV_EMBED>	1166	=item C<EV_EMBED>
1068		1167
1069	The embedded event loop specified in the C<ev_embed> watcher needs attention.	1168	The embedded event loop specified in the C<ev_embed> watcher needs attention.
1070		1169
1071	=item C<EV_FORK>	1170	=item C<EV_FORK>
1072		1171
1073	The event loop has been resumed in the child process after fork (see	1172	The event loop has been resumed in the child process after fork (see
1074	C<ev_fork>).	1173	C<ev_fork>).
		1174
		1175	=item C<EV_CLEANUP>
		1176
		1177	The event loop is about to be destroyed (see C<ev_cleanup>).
1075		1178
1076	=item C<EV_ASYNC>	1179	=item C<EV_ASYNC>
1077		1180
1078	The given async watcher has been asynchronously notified (see C<ev_async>).	1181	The given async watcher has been asynchronously notified (see C<ev_async>).
1079		1182
…		…
1126		1229
1127	ev_io w;	1230	ev_io w;
1128	ev_init (&w, my_cb);	1231	ev_init (&w, my_cb);
1129	ev_io_set (&w, STDIN_FILENO, EV_READ);	1232	ev_io_set (&w, STDIN_FILENO, EV_READ);
1130		1233
1131	=item C<ev_TYPE_set> (ev_TYPE *, [args])	1234	=item C<ev_TYPE_set> (ev_TYPE *watcher, [args])
1132		1235
1133	This macro initialises the type-specific parts of a watcher. You need to	1236	This macro initialises the type-specific parts of a watcher. You need to
1134	call C<ev_init> at least once before you call this macro, but you can	1237	call C<ev_init> at least once before you call this macro, but you can
1135	call C<ev_TYPE_set> any number of times. You must not, however, call this	1238	call C<ev_TYPE_set> any number of times. You must not, however, call this
1136	macro on a watcher that is active (it can be pending, however, which is a	1239	macro on a watcher that is active (it can be pending, however, which is a
…		…
1149		1252
1150	Example: Initialise and set an C<ev_io> watcher in one step.	1253	Example: Initialise and set an C<ev_io> watcher in one step.
1151		1254
1152	ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ);	1255	ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ);
1153		1256
1154	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)	1257	=item C<ev_TYPE_start> (loop, ev_TYPE *watcher)
1155		1258
1156	Starts (activates) the given watcher. Only active watchers will receive	1259	Starts (activates) the given watcher. Only active watchers will receive
1157	events. If the watcher is already active nothing will happen.	1260	events. If the watcher is already active nothing will happen.
1158		1261
1159	Example: Start the C<ev_io> watcher that is being abused as example in this	1262	Example: Start the C<ev_io> watcher that is being abused as example in this
1160	whole section.	1263	whole section.
1161		1264
1162	ev_io_start (EV_DEFAULT_UC, &w);	1265	ev_io_start (EV_DEFAULT_UC, &w);
1163		1266
1164	=item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher)	1267	=item C<ev_TYPE_stop> (loop, ev_TYPE *watcher)
1165		1268
1166	Stops the given watcher if active, and clears the pending status (whether	1269	Stops the given watcher if active, and clears the pending status (whether
1167	the watcher was active or not).	1270	the watcher was active or not).
1168		1271
1169	It is possible that stopped watchers are pending - for example,	1272	It is possible that stopped watchers are pending - for example,
…		…
1194	=item ev_cb_set (ev_TYPE *watcher, callback)	1297	=item ev_cb_set (ev_TYPE *watcher, callback)
1195		1298
1196	Change the callback. You can change the callback at virtually any time	1299	Change the callback. You can change the callback at virtually any time
1197	(modulo threads).	1300	(modulo threads).
1198		1301
1199	=item ev_set_priority (ev_TYPE *watcher, priority)	1302	=item ev_set_priority (ev_TYPE *watcher, int priority)
1200		1303
1201	=item int ev_priority (ev_TYPE *watcher)	1304	=item int ev_priority (ev_TYPE *watcher)
1202		1305
1203	Set and query the priority of the watcher. The priority is a small	1306	Set and query the priority of the watcher. The priority is a small
1204	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>	1307	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>
…		…
1236	watcher isn't pending it does nothing and returns C<0>.	1339	watcher isn't pending it does nothing and returns C<0>.
1237		1340
1238	Sometimes it can be useful to "poll" a watcher instead of waiting for its	1341	Sometimes it can be useful to "poll" a watcher instead of waiting for its
1239	callback to be invoked, which can be accomplished with this function.	1342	callback to be invoked, which can be accomplished with this function.
1240		1343
1241	=item ev_feed_event (struct ev_loop *, watcher *, int revents)	1344	=item ev_feed_event (loop, ev_TYPE *watcher, int revents)
1242		1345
1243	Feeds the given event set into the event loop, as if the specified event	1346	Feeds the given event set into the event loop, as if the specified event
1244	had happened for the specified watcher (which must be a pointer to an	1347	had happened for the specified watcher (which must be a pointer to an
1245	initialised but not necessarily started event watcher). Obviously you must	1348	initialised but not necessarily started event watcher). Obviously you must
1246	not free the watcher as long as it has pending events.	1349	not free the watcher as long as it has pending events.
…		…
1251		1354
1252	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related	1355	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related
1253	functions that do not need a watcher.	1356	functions that do not need a watcher.
1254		1357
1255	=back	1358	=back
1256
1257		1359
1258	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	1360	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
1259		1361
1260	Each watcher has, by default, a member C<void *data> that you can change	1362	Each watcher has, by default, a member C<void *data> that you can change
1261	and read at any time: libev will completely ignore it. This can be used	1363	and read at any time: libev will completely ignore it. This can be used
…		…
1317	t2_cb (EV_P_ ev_timer *w, int revents)	1419	t2_cb (EV_P_ ev_timer *w, int revents)
1318	{	1420	{
1319	struct my_biggy big = (struct my_biggy *)	1421	struct my_biggy big = (struct my_biggy *)
1320	(((char *)w) - offsetof (struct my_biggy, t2));	1422	(((char *)w) - offsetof (struct my_biggy, t2));
1321	}	1423	}
		1424
		1425	=head2 WATCHER STATES
		1426
		1427	There are various watcher states mentioned throughout this manual -
		1428	active, pending and so on. In this section these states and the rules to
		1429	transition between them will be described in more detail - and while these
		1430	rules might look complicated, they usually do "the right thing".
		1431
		1432	=over 4
		1433
		1434	=item initialiased
		1435
		1436	Before a watcher can be registered with the event looop it has to be
		1437	initialised. This can be done with a call to C<ev_TYPE_init>, or calls to
		1438	C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function.
		1439
		1440	In this state it is simply some block of memory that is suitable for use
		1441	in an event loop. It can be moved around, freed, reused etc. at will.
		1442
		1443	=item started/running/active
		1444
		1445	Once a watcher has been started with a call to C<ev_TYPE_start> it becomes
		1446	property of the event loop, and is actively waiting for events. While in
		1447	this state it cannot be accessed (except in a few documented ways), moved,
		1448	freed or anything else - the only legal thing is to keep a pointer to it,
		1449	and call libev functions on it that are documented to work on active watchers.
		1450
		1451	=item pending
		1452
		1453	If a watcher is active and libev determines that an event it is interested
		1454	in has occurred (such as a timer expiring), it will become pending. It will
		1455	stay in this pending state until either it is stopped or its callback is
		1456	about to be invoked, so it is not normally pending inside the watcher
		1457	callback.
		1458
		1459	The watcher might or might not be active while it is pending (for example,
		1460	an expired non-repeating timer can be pending but no longer active). If it
		1461	is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>),
		1462	but it is still property of the event loop at this time, so cannot be
		1463	moved, freed or reused. And if it is active the rules described in the
		1464	previous item still apply.
		1465
		1466	It is also possible to feed an event on a watcher that is not active (e.g.
		1467	via C<ev_feed_event>), in which case it becomes pending without being
		1468	active.
		1469
		1470	=item stopped
		1471
		1472	A watcher can be stopped implicitly by libev (in which case it might still
		1473	be pending), or explicitly by calling its C<ev_TYPE_stop> function. The
		1474	latter will clear any pending state the watcher might be in, regardless
		1475	of whether it was active or not, so stopping a watcher explicitly before
		1476	freeing it is often a good idea.
		1477
		1478	While stopped (and not pending) the watcher is essentially in the
		1479	initialised state, that is it can be reused, moved, modified in any way
		1480	you wish.
		1481
		1482	=back
1322		1483
1323	=head2 WATCHER PRIORITY MODELS	1484	=head2 WATCHER PRIORITY MODELS
1324		1485
1325	Many event loops support I<watcher priorities>, which are usually small	1486	Many event loops support I<watcher priorities>, which are usually small
1326	integers that influence the ordering of event callback invocation	1487	integers that influence the ordering of event callback invocation
…		…
1369		1530
1370	For example, to emulate how many other event libraries handle priorities,	1531	For example, to emulate how many other event libraries handle priorities,
1371	you can associate an C<ev_idle> watcher to each such watcher, and in	1532	you can associate an C<ev_idle> watcher to each such watcher, and in
1372	the normal watcher callback, you just start the idle watcher. The real	1533	the normal watcher callback, you just start the idle watcher. The real
1373	processing is done in the idle watcher callback. This causes libev to	1534	processing is done in the idle watcher callback. This causes libev to
1374	continously poll and process kernel event data for the watcher, but when	1535	continuously poll and process kernel event data for the watcher, but when
1375	the lock-out case is known to be rare (which in turn is rare :), this is	1536	the lock-out case is known to be rare (which in turn is rare :), this is
1376	workable.	1537	workable.
1377		1538
1378	Usually, however, the lock-out model implemented that way will perform	1539	Usually, however, the lock-out model implemented that way will perform
1379	miserably under the type of load it was designed to handle. In that case,	1540	miserably under the type of load it was designed to handle. In that case,
…		…
1393	{	1554	{
1394	// stop the I/O watcher, we received the event, but	1555	// stop the I/O watcher, we received the event, but
1395	// are not yet ready to handle it.	1556	// are not yet ready to handle it.
1396	ev_io_stop (EV_A_ w);	1557	ev_io_stop (EV_A_ w);
1397		1558
1398	// start the idle watcher to ahndle the actual event.	1559	// start the idle watcher to handle the actual event.
1399	// it will not be executed as long as other watchers	1560	// it will not be executed as long as other watchers
1400	// with the default priority are receiving events.	1561	// with the default priority are receiving events.
1401	ev_idle_start (EV_A_ &idle);	1562	ev_idle_start (EV_A_ &idle);
1402	}	1563	}
1403		1564
…		…
1457		1618
1458	If you cannot use non-blocking mode, then force the use of a	1619	If you cannot use non-blocking mode, then force the use of a
1459	known-to-be-good backend (at the time of this writing, this includes only	1620	known-to-be-good backend (at the time of this writing, this includes only
1460	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file	1621	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file
1461	descriptors for which non-blocking operation makes no sense (such as	1622	descriptors for which non-blocking operation makes no sense (such as
1462	files) - libev doesn't guarentee any specific behaviour in that case.	1623	files) - libev doesn't guarantee any specific behaviour in that case.
1463		1624
1464	Another thing you have to watch out for is that it is quite easy to	1625	Another thing you have to watch out for is that it is quite easy to
1465	receive "spurious" readiness notifications, that is your callback might	1626	receive "spurious" readiness notifications, that is your callback might
1466	be called with C<EV_READ> but a subsequent C<read>(2) will actually block	1627	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
1467	because there is no data. Not only are some backends known to create a	1628	because there is no data. Not only are some backends known to create a
…		…
1532		1693
1533	So when you encounter spurious, unexplained daemon exits, make sure you	1694	So when you encounter spurious, unexplained daemon exits, make sure you
1534	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon	1695	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon
1535	somewhere, as that would have given you a big clue).	1696	somewhere, as that would have given you a big clue).
1536		1697
		1698	=head3 The special problem of accept()ing when you can't
		1699
		1700	Many implementations of the POSIX C<accept> function (for example,
		1701	found in post-2004 Linux) have the peculiar behaviour of not removing a
		1702	connection from the pending queue in all error cases.
		1703
		1704	For example, larger servers often run out of file descriptors (because
		1705	of resource limits), causing C<accept> to fail with C<ENFILE> but not
		1706	rejecting the connection, leading to libev signalling readiness on
		1707	the next iteration again (the connection still exists after all), and
		1708	typically causing the program to loop at 100% CPU usage.
		1709
		1710	Unfortunately, the set of errors that cause this issue differs between
		1711	operating systems, there is usually little the app can do to remedy the
		1712	situation, and no known thread-safe method of removing the connection to
		1713	cope with overload is known (to me).
		1714
		1715	One of the easiest ways to handle this situation is to just ignore it
		1716	- when the program encounters an overload, it will just loop until the
		1717	situation is over. While this is a form of busy waiting, no OS offers an
		1718	event-based way to handle this situation, so it's the best one can do.
		1719
		1720	A better way to handle the situation is to log any errors other than
		1721	C<EAGAIN> and C<EWOULDBLOCK>, making sure not to flood the log with such
		1722	messages, and continue as usual, which at least gives the user an idea of
		1723	what could be wrong ("raise the ulimit!"). For extra points one could stop
		1724	the C<ev_io> watcher on the listening fd "for a while", which reduces CPU
		1725	usage.
		1726
		1727	If your program is single-threaded, then you could also keep a dummy file
		1728	descriptor for overload situations (e.g. by opening F</dev/null>), and
		1729	when you run into C<ENFILE> or C<EMFILE>, close it, run C<accept>,
		1730	close that fd, and create a new dummy fd. This will gracefully refuse
		1731	clients under typical overload conditions.
		1732
		1733	The last way to handle it is to simply log the error and C<exit>, as
		1734	is often done with C<malloc> failures, but this results in an easy
		1735	opportunity for a DoS attack.
1537		1736
1538	=head3 Watcher-Specific Functions	1737	=head3 Watcher-Specific Functions
1539		1738
1540	=over 4	1739	=over 4
1541		1740
…		…
1573	...	1772	...
1574	struct ev_loop *loop = ev_default_init (0);	1773	struct ev_loop *loop = ev_default_init (0);
1575	ev_io stdin_readable;	1774	ev_io stdin_readable;
1576	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1775	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1577	ev_io_start (loop, &stdin_readable);	1776	ev_io_start (loop, &stdin_readable);
1578	ev_loop (loop, 0);	1777	ev_run (loop, 0);
1579		1778
1580		1779
1581	=head2 C<ev_timer> - relative and optionally repeating timeouts	1780	=head2 C<ev_timer> - relative and optionally repeating timeouts
1582		1781
1583	Timer watchers are simple relative timers that generate an event after a	1782	Timer watchers are simple relative timers that generate an event after a
…		…
1592	The callback is guaranteed to be invoked only I<after> its timeout has	1791	The callback is guaranteed to be invoked only I<after> its timeout has
1593	passed (not I<at>, so on systems with very low-resolution clocks this	1792	passed (not I<at>, so on systems with very low-resolution clocks this
1594	might introduce a small delay). If multiple timers become ready during the	1793	might introduce a small delay). If multiple timers become ready during the
1595	same loop iteration then the ones with earlier time-out values are invoked	1794	same loop iteration then the ones with earlier time-out values are invoked
1596	before ones of the same priority with later time-out values (but this is	1795	before ones of the same priority with later time-out values (but this is
1597	no longer true when a callback calls C<ev_loop> recursively).	1796	no longer true when a callback calls C<ev_run> recursively).
1598		1797
1599	=head3 Be smart about timeouts	1798	=head3 Be smart about timeouts
1600		1799
1601	Many real-world problems involve some kind of timeout, usually for error	1800	Many real-world problems involve some kind of timeout, usually for error
1602	recovery. A typical example is an HTTP request - if the other side hangs,	1801	recovery. A typical example is an HTTP request - if the other side hangs,
…		…
1688	ev_tstamp timeout = last_activity + 60.;	1887	ev_tstamp timeout = last_activity + 60.;
1689		1888
1690	// if last_activity + 60. is older than now, we did time out	1889	// if last_activity + 60. is older than now, we did time out
1691	if (timeout < now)	1890	if (timeout < now)
1692	{	1891	{
1693	// timeout occured, take action	1892	// timeout occurred, take action
1694	}	1893	}
1695	else	1894	else
1696	{	1895	{
1697	// callback was invoked, but there was some activity, re-arm	1896	// callback was invoked, but there was some activity, re-arm
1698	// the watcher to fire in last_activity + 60, which is	1897	// the watcher to fire in last_activity + 60, which is
…		…
1720	to the current time (meaning we just have some activity :), then call the	1919	to the current time (meaning we just have some activity :), then call the
1721	callback, which will "do the right thing" and start the timer:	1920	callback, which will "do the right thing" and start the timer:
1722		1921
1723	ev_init (timer, callback);	1922	ev_init (timer, callback);
1724	last_activity = ev_now (loop);	1923	last_activity = ev_now (loop);
1725	callback (loop, timer, EV_TIMEOUT);	1924	callback (loop, timer, EV_TIMER);
1726		1925
1727	And when there is some activity, simply store the current time in	1926	And when there is some activity, simply store the current time in
1728	C<last_activity>, no libev calls at all:	1927	C<last_activity>, no libev calls at all:
1729		1928
1730	last_actiivty = ev_now (loop);	1929	last_activity = ev_now (loop);
1731		1930
1732	This technique is slightly more complex, but in most cases where the	1931	This technique is slightly more complex, but in most cases where the
1733	time-out is unlikely to be triggered, much more efficient.	1932	time-out is unlikely to be triggered, much more efficient.
1734		1933
1735	Changing the timeout is trivial as well (if it isn't hard-coded in the	1934	Changing the timeout is trivial as well (if it isn't hard-coded in the
…		…
1773		1972
1774	=head3 The special problem of time updates	1973	=head3 The special problem of time updates
1775		1974
1776	Establishing the current time is a costly operation (it usually takes at	1975	Establishing the current time is a costly operation (it usually takes at
1777	least two system calls): EV therefore updates its idea of the current	1976	least two system calls): EV therefore updates its idea of the current
1778	time only before and after C<ev_loop> collects new events, which causes a	1977	time only before and after C<ev_run> collects new events, which causes a
1779	growing difference between C<ev_now ()> and C<ev_time ()> when handling	1978	growing difference between C<ev_now ()> and C<ev_time ()> when handling
1780	lots of events in one iteration.	1979	lots of events in one iteration.
1781		1980
1782	The relative timeouts are calculated relative to the C<ev_now ()>	1981	The relative timeouts are calculated relative to the C<ev_now ()>
1783	time. This is usually the right thing as this timestamp refers to the time	1982	time. This is usually the right thing as this timestamp refers to the time
…		…
1854	C<repeat> value), or reset the running timer to the C<repeat> value.	2053	C<repeat> value), or reset the running timer to the C<repeat> value.
1855		2054
1856	This sounds a bit complicated, see L<Be smart about timeouts>, above, for a	2055	This sounds a bit complicated, see L<Be smart about timeouts>, above, for a
1857	usage example.	2056	usage example.
1858		2057
1859	=item ev_timer_remaining (loop, ev_timer *)	2058	=item ev_tstamp ev_timer_remaining (loop, ev_timer *)
1860		2059
1861	Returns the remaining time until a timer fires. If the timer is active,	2060	Returns the remaining time until a timer fires. If the timer is active,
1862	then this time is relative to the current event loop time, otherwise it's	2061	then this time is relative to the current event loop time, otherwise it's
1863	the timeout value currently configured.	2062	the timeout value currently configured.
1864		2063
1865	That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns	2064	That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns
1866	C<5>. When the timer is started and one second passes, C<ev_timer_remain>	2065	C<5>. When the timer is started and one second passes, C<ev_timer_remaining>
1867	will return C<4>. When the timer expires and is restarted, it will return	2066	will return C<4>. When the timer expires and is restarted, it will return
1868	roughly C<7> (likely slightly less as callback invocation takes some time,	2067	roughly C<7> (likely slightly less as callback invocation takes some time,
1869	too), and so on.	2068	too), and so on.
1870		2069
1871	=item ev_tstamp repeat [read-write]	2070	=item ev_tstamp repeat [read-write]
…		…
1900	}	2099	}
1901		2100
1902	ev_timer mytimer;	2101	ev_timer mytimer;
1903	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	2102	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1904	ev_timer_again (&mytimer); /* start timer */	2103	ev_timer_again (&mytimer); /* start timer */
1905	ev_loop (loop, 0);	2104	ev_run (loop, 0);
1906		2105
1907	// and in some piece of code that gets executed on any "activity":	2106	// and in some piece of code that gets executed on any "activity":
1908	// reset the timeout to start ticking again at 10 seconds	2107	// reset the timeout to start ticking again at 10 seconds
1909	ev_timer_again (&mytimer);	2108	ev_timer_again (&mytimer);
1910		2109
…		…
1936		2135
1937	As with timers, the callback is guaranteed to be invoked only when the	2136	As with timers, the callback is guaranteed to be invoked only when the
1938	point in time where it is supposed to trigger has passed. If multiple	2137	point in time where it is supposed to trigger has passed. If multiple
1939	timers become ready during the same loop iteration then the ones with	2138	timers become ready during the same loop iteration then the ones with
1940	earlier time-out values are invoked before ones with later time-out values	2139	earlier time-out values are invoked before ones with later time-out values
1941	(but this is no longer true when a callback calls C<ev_loop> recursively).	2140	(but this is no longer true when a callback calls C<ev_run> recursively).
1942		2141
1943	=head3 Watcher-Specific Functions and Data Members	2142	=head3 Watcher-Specific Functions and Data Members
1944		2143
1945	=over 4	2144	=over 4
1946		2145
…		…
2074	Example: Call a callback every hour, or, more precisely, whenever the	2273	Example: Call a callback every hour, or, more precisely, whenever the
2075	system time is divisible by 3600. The callback invocation times have	2274	system time is divisible by 3600. The callback invocation times have
2076	potentially a lot of jitter, but good long-term stability.	2275	potentially a lot of jitter, but good long-term stability.
2077		2276
2078	static void	2277	static void
2079	clock_cb (struct ev_loop *loop, ev_io *w, int revents)	2278	clock_cb (struct ev_loop *loop, ev_periodic *w, int revents)
2080	{	2279	{
2081	... its now a full hour (UTC, or TAI or whatever your clock follows)	2280	... its now a full hour (UTC, or TAI or whatever your clock follows)
2082	}	2281	}
2083		2282
2084	ev_periodic hourly_tick;	2283	ev_periodic hourly_tick;
…		…
2107		2306
2108	=head2 C<ev_signal> - signal me when a signal gets signalled!	2307	=head2 C<ev_signal> - signal me when a signal gets signalled!
2109		2308
2110	Signal watchers will trigger an event when the process receives a specific	2309	Signal watchers will trigger an event when the process receives a specific
2111	signal one or more times. Even though signals are very asynchronous, libev	2310	signal one or more times. Even though signals are very asynchronous, libev
2112	will try it's best to deliver signals synchronously, i.e. as part of the	2311	will try its best to deliver signals synchronously, i.e. as part of the
2113	normal event processing, like any other event.	2312	normal event processing, like any other event.
2114		2313
2115	If you want signals to be delivered truly asynchronously, just use	2314	If you want signals to be delivered truly asynchronously, just use
2116	C<sigaction> as you would do without libev and forget about sharing	2315	C<sigaction> as you would do without libev and forget about sharing
2117	the signal. You can even use C<ev_async> from a signal handler to	2316	the signal. You can even use C<ev_async> from a signal handler to
…		…
2131	C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should	2330	C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should
2132	not be unduly interrupted. If you have a problem with system calls getting	2331	not be unduly interrupted. If you have a problem with system calls getting
2133	interrupted by signals you can block all signals in an C<ev_check> watcher	2332	interrupted by signals you can block all signals in an C<ev_check> watcher
2134	and unblock them in an C<ev_prepare> watcher.	2333	and unblock them in an C<ev_prepare> watcher.
2135		2334
2136	=head3 The special problem of inheritance over execve	2335	=head3 The special problem of inheritance over fork/execve/pthread_create
2137		2336
2138	Both the signal mask (C<sigprocmask>) and the signal disposition	2337	Both the signal mask (C<sigprocmask>) and the signal disposition
2139	(C<sigaction>) are unspecified after starting a signal watcher (and after	2338	(C<sigaction>) are unspecified after starting a signal watcher (and after
2140	stopping it again), that is, libev might or might not block the signal,	2339	stopping it again), that is, libev might or might not block the signal,
2141	and might or might not set or restore the installed signal handler.	2340	and might or might not set or restore the installed signal handler.
…		…
2151		2350
2152	The simplest way to ensure that the signal mask is reset in the child is	2351	The simplest way to ensure that the signal mask is reset in the child is
2153	to install a fork handler with C<pthread_atfork> that resets it. That will	2352	to install a fork handler with C<pthread_atfork> that resets it. That will
2154	catch fork calls done by libraries (such as the libc) as well.	2353	catch fork calls done by libraries (such as the libc) as well.
2155		2354
2156	In current versions of libev, you can also ensure that the signal mask is	2355	In current versions of libev, the signal will not be blocked indefinitely
2157	not blocking any signals (except temporarily, so thread users watch out)	2356	unless you use the C<signalfd> API (C<EV_SIGNALFD>). While this reduces
2158	by specifying the C<EVFLAG_NOSIGFD> when creating the event loop. This	2357	the window of opportunity for problems, it will not go away, as libev
2159	is not guaranteed for future versions, however.	2358	I<has> to modify the signal mask, at least temporarily.
		2359
		2360	So I can't stress this enough: I<If you do not reset your signal mask when
		2361	you expect it to be empty, you have a race condition in your code>. This
		2362	is not a libev-specific thing, this is true for most event libraries.
		2363
		2364	=head3 The special problem of threads signal handling
		2365
		2366	POSIX threads has problematic signal handling semantics, specifically,
		2367	a lot of functionality (sigfd, sigwait etc.) only really works if all
		2368	threads in a process block signals, which is hard to achieve.
		2369
		2370	When you want to use sigwait (or mix libev signal handling with your own
		2371	for the same signals), you can tackle this problem by globally blocking
		2372	all signals before creating any threads (or creating them with a fully set
		2373	sigprocmask) and also specifying the C<EVFLAG_NOSIGMASK> when creating
		2374	loops. Then designate one thread as "signal receiver thread" which handles
		2375	these signals. You can pass on any signals that libev might be interested
		2376	in by calling C<ev_feed_signal>.
2160		2377
2161	=head3 Watcher-Specific Functions and Data Members	2378	=head3 Watcher-Specific Functions and Data Members
2162		2379
2163	=over 4	2380	=over 4
2164		2381
…		…
2180	Example: Try to exit cleanly on SIGINT.	2397	Example: Try to exit cleanly on SIGINT.
2181		2398
2182	static void	2399	static void
2183	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)	2400	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)
2184	{	2401	{
2185	ev_unloop (loop, EVUNLOOP_ALL);	2402	ev_break (loop, EVBREAK_ALL);
2186	}	2403	}
2187		2404
2188	ev_signal signal_watcher;	2405	ev_signal signal_watcher;
2189	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	2406	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
2190	ev_signal_start (loop, &signal_watcher);	2407	ev_signal_start (loop, &signal_watcher);
…		…
2576		2793
2577	Prepare and check watchers are usually (but not always) used in pairs:	2794	Prepare and check watchers are usually (but not always) used in pairs:
2578	prepare watchers get invoked before the process blocks and check watchers	2795	prepare watchers get invoked before the process blocks and check watchers
2579	afterwards.	2796	afterwards.
2580		2797
2581	You I<must not> call C<ev_loop> or similar functions that enter	2798	You I<must not> call C<ev_run> or similar functions that enter
2582	the current event loop from either C<ev_prepare> or C<ev_check>	2799	the current event loop from either C<ev_prepare> or C<ev_check>
2583	watchers. Other loops than the current one are fine, however. The	2800	watchers. Other loops than the current one are fine, however. The
2584	rationale behind this is that you do not need to check for recursion in	2801	rationale behind this is that you do not need to check for recursion in
2585	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,	2802	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,
2586	C<ev_check> so if you have one watcher of each kind they will always be	2803	C<ev_check> so if you have one watcher of each kind they will always be
…		…
2754		2971
2755	if (timeout >= 0)	2972	if (timeout >= 0)
2756	// create/start timer	2973	// create/start timer
2757		2974
2758	// poll	2975	// poll
2759	ev_loop (EV_A_ 0);	2976	ev_run (EV_A_ 0);
2760		2977
2761	// stop timer again	2978	// stop timer again
2762	if (timeout >= 0)	2979	if (timeout >= 0)
2763	ev_timer_stop (EV_A_ &to);	2980	ev_timer_stop (EV_A_ &to);
2764		2981
…		…
2842	if you do not want that, you need to temporarily stop the embed watcher).	3059	if you do not want that, you need to temporarily stop the embed watcher).
2843		3060
2844	=item ev_embed_sweep (loop, ev_embed *)	3061	=item ev_embed_sweep (loop, ev_embed *)
2845		3062
2846	Make a single, non-blocking sweep over the embedded loop. This works	3063	Make a single, non-blocking sweep over the embedded loop. This works
2847	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	3064	similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most
2848	appropriate way for embedded loops.	3065	appropriate way for embedded loops.
2849		3066
2850	=item struct ev_loop *other [read-only]	3067	=item struct ev_loop *other [read-only]
2851		3068
2852	The embedded event loop.	3069	The embedded event loop.
…		…
2912	C<ev_default_fork> cheats and calls it in the wrong process, the fork	3129	C<ev_default_fork> cheats and calls it in the wrong process, the fork
2913	handlers will be invoked, too, of course.	3130	handlers will be invoked, too, of course.
2914		3131
2915	=head3 The special problem of life after fork - how is it possible?	3132	=head3 The special problem of life after fork - how is it possible?
2916		3133
2917	Most uses of C<fork()> consist of forking, then some simple calls to ste	3134	Most uses of C<fork()> consist of forking, then some simple calls to set
2918	up/change the process environment, followed by a call to C<exec()>. This	3135	up/change the process environment, followed by a call to C<exec()>. This
2919	sequence should be handled by libev without any problems.	3136	sequence should be handled by libev without any problems.
2920		3137
2921	This changes when the application actually wants to do event handling	3138	This changes when the application actually wants to do event handling
2922	in the child, or both parent in child, in effect "continuing" after the	3139	in the child, or both parent in child, in effect "continuing" after the
…		…
2938	disadvantage of having to use multiple event loops (which do not support	3155	disadvantage of having to use multiple event loops (which do not support
2939	signal watchers).	3156	signal watchers).
2940		3157
2941	When this is not possible, or you want to use the default loop for	3158	When this is not possible, or you want to use the default loop for
2942	other reasons, then in the process that wants to start "fresh", call	3159	other reasons, then in the process that wants to start "fresh", call
2943	C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying	3160	C<ev_loop_destroy (EV_DEFAULT)> followed by C<ev_default_loop (...)>.
2944	the default loop will "orphan" (not stop) all registered watchers, so you	3161	Destroying the default loop will "orphan" (not stop) all registered
2945	have to be careful not to execute code that modifies those watchers. Note	3162	watchers, so you have to be careful not to execute code that modifies
2946	also that in that case, you have to re-register any signal watchers.	3163	those watchers. Note also that in that case, you have to re-register any
		3164	signal watchers.
2947		3165
2948	=head3 Watcher-Specific Functions and Data Members	3166	=head3 Watcher-Specific Functions and Data Members
2949		3167
2950	=over 4	3168	=over 4
2951		3169
2952	=item ev_fork_init (ev_signal *, callback)	3170	=item ev_fork_init (ev_fork *, callback)
2953		3171
2954	Initialises and configures the fork watcher - it has no parameters of any	3172	Initialises and configures the fork watcher - it has no parameters of any
2955	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,	3173	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
2956	believe me.	3174	really.
2957		3175
2958	=back	3176	=back
2959		3177
2960		3178
		3179	=head2 C<ev_cleanup> - even the best things end
		3180
		3181	Cleanup watchers are called just before the event loop is being destroyed
		3182	by a call to C<ev_loop_destroy>.
		3183
		3184	While there is no guarantee that the event loop gets destroyed, cleanup
		3185	watchers provide a convenient method to install cleanup hooks for your
		3186	program, worker threads and so on - you just to make sure to destroy the
		3187	loop when you want them to be invoked.
		3188
		3189	Cleanup watchers are invoked in the same way as any other watcher. Unlike
		3190	all other watchers, they do not keep a reference to the event loop (which
		3191	makes a lot of sense if you think about it). Like all other watchers, you
		3192	can call libev functions in the callback, except C<ev_cleanup_start>.
		3193
		3194	=head3 Watcher-Specific Functions and Data Members
		3195
		3196	=over 4
		3197
		3198	=item ev_cleanup_init (ev_cleanup *, callback)
		3199
		3200	Initialises and configures the cleanup watcher - it has no parameters of
		3201	any kind. There is a C<ev_cleanup_set> macro, but using it is utterly
		3202	pointless, I assure you.
		3203
		3204	=back
		3205
		3206	Example: Register an atexit handler to destroy the default loop, so any
		3207	cleanup functions are called.
		3208
		3209	static void
		3210	program_exits (void)
		3211	{
		3212	ev_loop_destroy (EV_DEFAULT_UC);
		3213	}
		3214
		3215	...
		3216	atexit (program_exits);
		3217
		3218
2961	=head2 C<ev_async> - how to wake up another event loop	3219	=head2 C<ev_async> - how to wake up an event loop
2962		3220
2963	In general, you cannot use an C<ev_loop> from multiple threads or other	3221	In general, you cannot use an C<ev_run> from multiple threads or other
2964	asynchronous sources such as signal handlers (as opposed to multiple event	3222	asynchronous sources such as signal handlers (as opposed to multiple event
2965	loops - those are of course safe to use in different threads).	3223	loops - those are of course safe to use in different threads).
2966		3224
2967	Sometimes, however, you need to wake up another event loop you do not	3225	Sometimes, however, you need to wake up an event loop you do not control,
2968	control, for example because it belongs to another thread. This is what	3226	for example because it belongs to another thread. This is what C<ev_async>
2969	C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you	3227	watchers do: as long as the C<ev_async> watcher is active, you can signal
2970	can signal it by calling C<ev_async_send>, which is thread- and signal	3228	it by calling C<ev_async_send>, which is thread- and signal safe.
2971	safe.
2972		3229
2973	This functionality is very similar to C<ev_signal> watchers, as signals,	3230	This functionality is very similar to C<ev_signal> watchers, as signals,
2974	too, are asynchronous in nature, and signals, too, will be compressed	3231	too, are asynchronous in nature, and signals, too, will be compressed
2975	(i.e. the number of callback invocations may be less than the number of	3232	(i.e. the number of callback invocations may be less than the number of
2976	C<ev_async_sent> calls).	3233	C<ev_async_sent> calls). In fact, you could use signal watchers as a kind
		3234	of "global async watchers" by using a watcher on an otherwise unused
		3235	signal, and C<ev_feed_signal> to signal this watcher from another thread,
		3236	even without knowing which loop owns the signal.
2977		3237
2978	Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not	3238	Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not
2979	just the default loop.	3239	just the default loop.
2980		3240
2981	=head3 Queueing	3241	=head3 Queueing
2982		3242
2983	C<ev_async> does not support queueing of data in any way. The reason	3243	C<ev_async> does not support queueing of data in any way. The reason
2984	is that the author does not know of a simple (or any) algorithm for a	3244	is that the author does not know of a simple (or any) algorithm for a
2985	multiple-writer-single-reader queue that works in all cases and doesn't	3245	multiple-writer-single-reader queue that works in all cases and doesn't
2986	need elaborate support such as pthreads.	3246	need elaborate support such as pthreads or unportable memory access
		3247	semantics.
2987		3248
2988	That means that if you want to queue data, you have to provide your own	3249	That means that if you want to queue data, you have to provide your own
2989	queue. But at least I can tell you how to implement locking around your	3250	queue. But at least I can tell you how to implement locking around your
2990	queue:	3251	queue:
2991		3252
…		…
3130		3391
3131	If C<timeout> is less than 0, then no timeout watcher will be	3392	If C<timeout> is less than 0, then no timeout watcher will be
3132	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and	3393	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and
3133	repeat = 0) will be started. C<0> is a valid timeout.	3394	repeat = 0) will be started. C<0> is a valid timeout.
3134		3395
3135	The callback has the type C<void (*cb)(int revents, void *arg)> and gets	3396	The callback has the type C<void (*cb)(int revents, void *arg)> and is
3136	passed an C<revents> set like normal event callbacks (a combination of	3397	passed an C<revents> set like normal event callbacks (a combination of
3137	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>	3398	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMER>) and the C<arg>
3138	value passed to C<ev_once>. Note that it is possible to receive I<both>	3399	value passed to C<ev_once>. Note that it is possible to receive I<both>
3139	a timeout and an io event at the same time - you probably should give io	3400	a timeout and an io event at the same time - you probably should give io
3140	events precedence.	3401	events precedence.
3141		3402
3142	Example: wait up to ten seconds for data to appear on STDIN_FILENO.	3403	Example: wait up to ten seconds for data to appear on STDIN_FILENO.
3143		3404
3144	static void stdin_ready (int revents, void *arg)	3405	static void stdin_ready (int revents, void *arg)
3145	{	3406	{
3146	if (revents & EV_READ)	3407	if (revents & EV_READ)
3147	/* stdin might have data for us, joy! */;	3408	/* stdin might have data for us, joy! */;
3148	else if (revents & EV_TIMEOUT)	3409	else if (revents & EV_TIMER)
3149	/* doh, nothing entered */;	3410	/* doh, nothing entered */;
3150	}	3411	}
3151		3412
3152	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	3413	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
3153		3414
3154	=item ev_feed_fd_event (struct ev_loop *, int fd, int revents)	3415	=item ev_feed_fd_event (loop, int fd, int revents)
3155		3416
3156	Feed an event on the given fd, as if a file descriptor backend detected	3417	Feed an event on the given fd, as if a file descriptor backend detected
3157	the given events it.	3418	the given events it.
3158		3419
3159	=item ev_feed_signal_event (struct ev_loop *loop, int signum)	3420	=item ev_feed_signal_event (loop, int signum)
3160		3421
3161	Feed an event as if the given signal occurred (C<loop> must be the default	3422	Feed an event as if the given signal occurred. See also C<ev_feed_signal>,
3162	loop!).	3423	which is async-safe.
		3424
		3425	=back
		3426
		3427
		3428	=head1 COMMON OR USEFUL IDIOMS (OR BOTH)
		3429
		3430	This section explains some common idioms that are not immediately
		3431	obvious. Note that examples are sprinkled over the whole manual, and this
		3432	section only contains stuff that wouldn't fit anywhere else.
		3433
		3434	=over 4
		3435
		3436	=item Model/nested event loop invocations and exit conditions.
		3437
		3438	Often (especially in GUI toolkits) there are places where you have
		3439	I<modal> interaction, which is most easily implemented by recursively
		3440	invoking C<ev_run>.
		3441
		3442	This brings the problem of exiting - a callback might want to finish the
		3443	main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but
		3444	a modal "Are you sure?" dialog is still waiting), or just the nested one
		3445	and not the main one (e.g. user clocked "Ok" in a modal dialog), or some
		3446	other combination: In these cases, C<ev_break> will not work alone.
		3447
		3448	The solution is to maintain "break this loop" variable for each C<ev_run>
		3449	invocation, and use a loop around C<ev_run> until the condition is
		3450	triggered, using C<EVRUN_ONCE>:
		3451
		3452	// main loop
		3453	int exit_main_loop = 0;
		3454
		3455	while (!exit_main_loop)
		3456	ev_run (EV_DEFAULT_ EVRUN_ONCE);
		3457
		3458	// in a model watcher
		3459	int exit_nested_loop = 0;
		3460
		3461	while (!exit_nested_loop)
		3462	ev_run (EV_A_ EVRUN_ONCE);
		3463
		3464	To exit from any of these loops, just set the corresponding exit variable:
		3465
		3466	// exit modal loop
		3467	exit_nested_loop = 1;
		3468
		3469	// exit main program, after modal loop is finished
		3470	exit_main_loop = 1;
		3471
		3472	// exit both
		3473	exit_main_loop = exit_nested_loop = 1;
3163		3474
3164	=back	3475	=back
3165		3476
3166		3477
3167	=head1 LIBEVENT EMULATION	3478	=head1 LIBEVENT EMULATION
3168		3479
3169	Libev offers a compatibility emulation layer for libevent. It cannot	3480	Libev offers a compatibility emulation layer for libevent. It cannot
3170	emulate the internals of libevent, so here are some usage hints:	3481	emulate the internals of libevent, so here are some usage hints:
3171		3482
3172	=over 4	3483	=over 4
		3484
		3485	=item * Only the libevent-1.4.1-beta API is being emulated.
		3486
		3487	This was the newest libevent version available when libev was implemented,
		3488	and is still mostly unchanged in 2010.
3173		3489
3174	=item * Use it by including <event.h>, as usual.	3490	=item * Use it by including <event.h>, as usual.
3175		3491
3176	=item * The following members are fully supported: ev_base, ev_callback,	3492	=item * The following members are fully supported: ev_base, ev_callback,
3177	ev_arg, ev_fd, ev_res, ev_events.	3493	ev_arg, ev_fd, ev_res, ev_events.
…		…
3183	=item * Priorities are not currently supported. Initialising priorities	3499	=item * Priorities are not currently supported. Initialising priorities
3184	will fail and all watchers will have the same priority, even though there	3500	will fail and all watchers will have the same priority, even though there
3185	is an ev_pri field.	3501	is an ev_pri field.
3186		3502
3187	=item * In libevent, the last base created gets the signals, in libev, the	3503	=item * In libevent, the last base created gets the signals, in libev, the
3188	first base created (== the default loop) gets the signals.	3504	base that registered the signal gets the signals.
3189		3505
3190	=item * Other members are not supported.	3506	=item * Other members are not supported.
3191		3507
3192	=item * The libev emulation is I<not> ABI compatible to libevent, you need	3508	=item * The libev emulation is I<not> ABI compatible to libevent, you need
3193	to use the libev header file and library.	3509	to use the libev header file and library.
…		…
3212	Care has been taken to keep the overhead low. The only data member the C++	3528	Care has been taken to keep the overhead low. The only data member the C++
3213	classes add (compared to plain C-style watchers) is the event loop pointer	3529	classes add (compared to plain C-style watchers) is the event loop pointer
3214	that the watcher is associated with (or no additional members at all if	3530	that the watcher is associated with (or no additional members at all if
3215	you disable C<EV_MULTIPLICITY> when embedding libev).	3531	you disable C<EV_MULTIPLICITY> when embedding libev).
3216		3532
3217	Currently, functions, and static and non-static member functions can be	3533	Currently, functions, static and non-static member functions and classes
3218	used as callbacks. Other types should be easy to add as long as they only	3534	with C<operator ()> can be used as callbacks. Other types should be easy
3219	need one additional pointer for context. If you need support for other	3535	to add as long as they only need one additional pointer for context. If
3220	types of functors please contact the author (preferably after implementing	3536	you need support for other types of functors please contact the author
3221	it).	3537	(preferably after implementing it).
3222		3538
3223	Here is a list of things available in the C<ev> namespace:	3539	Here is a list of things available in the C<ev> namespace:
3224		3540
3225	=over 4	3541	=over 4
3226		3542
…		…
3244		3560
3245	=over 4	3561	=over 4
3246		3562
3247	=item ev::TYPE::TYPE ()	3563	=item ev::TYPE::TYPE ()
3248		3564
3249	=item ev::TYPE::TYPE (struct ev_loop *)	3565	=item ev::TYPE::TYPE (loop)
3250		3566
3251	=item ev::TYPE::~TYPE	3567	=item ev::TYPE::~TYPE
3252		3568
3253	The constructor (optionally) takes an event loop to associate the watcher	3569	The constructor (optionally) takes an event loop to associate the watcher
3254	with. If it is omitted, it will use C<EV_DEFAULT>.	3570	with. If it is omitted, it will use C<EV_DEFAULT>.
…		…
3287	myclass obj;	3603	myclass obj;
3288	ev::io iow;	3604	ev::io iow;
3289	iow.set <myclass, &myclass::io_cb> (&obj);	3605	iow.set <myclass, &myclass::io_cb> (&obj);
3290		3606
3291	=item w->set (object *)	3607	=item w->set (object *)
3292
3293	This is an B<experimental> feature that might go away in a future version.
3294		3608
3295	This is a variation of a method callback - leaving out the method to call	3609	This is a variation of a method callback - leaving out the method to call
3296	will default the method to C<operator ()>, which makes it possible to use	3610	will default the method to C<operator ()>, which makes it possible to use
3297	functor objects without having to manually specify the C<operator ()> all	3611	functor objects without having to manually specify the C<operator ()> all
3298	the time. Incidentally, you can then also leave out the template argument	3612	the time. Incidentally, you can then also leave out the template argument
…		…
3331	Example: Use a plain function as callback.	3645	Example: Use a plain function as callback.
3332		3646
3333	static void io_cb (ev::io &w, int revents) { }	3647	static void io_cb (ev::io &w, int revents) { }
3334	iow.set <io_cb> ();	3648	iow.set <io_cb> ();
3335		3649
3336	=item w->set (struct ev_loop *)	3650	=item w->set (loop)
3337		3651
3338	Associates a different C<struct ev_loop> with this watcher. You can only	3652	Associates a different C<struct ev_loop> with this watcher. You can only
3339	do this when the watcher is inactive (and not pending either).	3653	do this when the watcher is inactive (and not pending either).
3340		3654
3341	=item w->set ([arguments])	3655	=item w->set ([arguments])
3342		3656
3343	Basically the same as C<ev_TYPE_set>, with the same arguments. Must be	3657	Basically the same as C<ev_TYPE_set>, with the same arguments. Either this
3344	called at least once. Unlike the C counterpart, an active watcher gets	3658	method or a suitable start method must be called at least once. Unlike the
3345	automatically stopped and restarted when reconfiguring it with this	3659	C counterpart, an active watcher gets automatically stopped and restarted
3346	method.	3660	when reconfiguring it with this method.
3347		3661
3348	=item w->start ()	3662	=item w->start ()
3349		3663
3350	Starts the watcher. Note that there is no C<loop> argument, as the	3664	Starts the watcher. Note that there is no C<loop> argument, as the
3351	constructor already stores the event loop.	3665	constructor already stores the event loop.
3352		3666
		3667	=item w->start ([arguments])
		3668
		3669	Instead of calling C<set> and C<start> methods separately, it is often
		3670	convenient to wrap them in one call. Uses the same type of arguments as
		3671	the configure C<set> method of the watcher.
		3672
3353	=item w->stop ()	3673	=item w->stop ()
3354		3674
3355	Stops the watcher if it is active. Again, no C<loop> argument.	3675	Stops the watcher if it is active. Again, no C<loop> argument.
3356		3676
3357	=item w->again () (C<ev::timer>, C<ev::periodic> only)	3677	=item w->again () (C<ev::timer>, C<ev::periodic> only)
…		…
3369		3689
3370	=back	3690	=back
3371		3691
3372	=back	3692	=back
3373		3693
3374	Example: Define a class with an IO and idle watcher, start one of them in	3694	Example: Define a class with two I/O and idle watchers, start the I/O
3375	the constructor.	3695	watchers in the constructor.
3376		3696
3377	class myclass	3697	class myclass
3378	{	3698	{
3379	ev::io io ; void io_cb (ev::io &w, int revents);	3699	ev::io io ; void io_cb (ev::io &w, int revents);
		3700	ev::io2 io2 ; void io2_cb (ev::io &w, int revents);
3380	ev::idle idle; void idle_cb (ev::idle &w, int revents);	3701	ev::idle idle; void idle_cb (ev::idle &w, int revents);
3381		3702
3382	myclass (int fd)	3703	myclass (int fd)
3383	{	3704	{
3384	io .set <myclass, &myclass::io_cb > (this);	3705	io .set <myclass, &myclass::io_cb > (this);
		3706	io2 .set <myclass, &myclass::io2_cb > (this);
3385	idle.set <myclass, &myclass::idle_cb> (this);	3707	idle.set <myclass, &myclass::idle_cb> (this);
3386		3708
3387	io.start (fd, ev::READ);	3709	io.set (fd, ev::WRITE); // configure the watcher
		3710	io.start (); // start it whenever convenient
		3711
		3712	io2.start (fd, ev::READ); // set + start in one call
3388	}	3713	}
3389	};	3714	};
3390		3715
3391		3716
3392	=head1 OTHER LANGUAGE BINDINGS	3717	=head1 OTHER LANGUAGE BINDINGS
…		…
3440	Erkki Seppala has written Ocaml bindings for libev, to be found at	3765	Erkki Seppala has written Ocaml bindings for libev, to be found at
3441	L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>.	3766	L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>.
3442		3767
3443	=item Lua	3768	=item Lua
3444		3769
3445	Brian Maher has written a partial interface to libev	3770	Brian Maher has written a partial interface to libev for lua (at the
3446	for lua (only C<ev_io> and C<ev_timer>), to be found at	3771	time of this writing, only C<ev_io> and C<ev_timer>), to be found at
3447	L<http://github.com/brimworks/lua-ev>.	3772	L<http://github.com/brimworks/lua-ev>.
3448		3773
3449	=back	3774	=back
3450		3775
3451		3776
…		…
3466	loop argument"). The C<EV_A> form is used when this is the sole argument,	3791	loop argument"). The C<EV_A> form is used when this is the sole argument,
3467	C<EV_A_> is used when other arguments are following. Example:	3792	C<EV_A_> is used when other arguments are following. Example:
3468		3793
3469	ev_unref (EV_A);	3794	ev_unref (EV_A);
3470	ev_timer_add (EV_A_ watcher);	3795	ev_timer_add (EV_A_ watcher);
3471	ev_loop (EV_A_ 0);	3796	ev_run (EV_A_ 0);
3472		3797
3473	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	3798	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
3474	which is often provided by the following macro.	3799	which is often provided by the following macro.
3475		3800
3476	=item C<EV_P>, C<EV_P_>	3801	=item C<EV_P>, C<EV_P_>
…		…
3516	}	3841	}
3517		3842
3518	ev_check check;	3843	ev_check check;
3519	ev_check_init (&check, check_cb);	3844	ev_check_init (&check, check_cb);
3520	ev_check_start (EV_DEFAULT_ &check);	3845	ev_check_start (EV_DEFAULT_ &check);
3521	ev_loop (EV_DEFAULT_ 0);	3846	ev_run (EV_DEFAULT_ 0);
3522		3847
3523	=head1 EMBEDDING	3848	=head1 EMBEDDING
3524		3849
3525	Libev can (and often is) directly embedded into host	3850	Libev can (and often is) directly embedded into host
3526	applications. Examples of applications that embed it include the Deliantra	3851	applications. Examples of applications that embed it include the Deliantra
…		…
3606	libev.m4	3931	libev.m4
3607		3932
3608	=head2 PREPROCESSOR SYMBOLS/MACROS	3933	=head2 PREPROCESSOR SYMBOLS/MACROS
3609		3934
3610	Libev can be configured via a variety of preprocessor symbols you have to	3935	Libev can be configured via a variety of preprocessor symbols you have to
3611	define before including any of its files. The default in the absence of	3936	define before including (or compiling) any of its files. The default in
3612	autoconf is documented for every option.	3937	the absence of autoconf is documented for every option.
		3938
		3939	Symbols marked with "(h)" do not change the ABI, and can have different
		3940	values when compiling libev vs. including F<ev.h>, so it is permissible
		3941	to redefine them before including F<ev.h> without breaking compatibility
		3942	to a compiled library. All other symbols change the ABI, which means all
		3943	users of libev and the libev code itself must be compiled with compatible
		3944	settings.
3613		3945
3614	=over 4	3946	=over 4
3615		3947
		3948	=item EV_COMPAT3 (h)
		3949
		3950	Backwards compatibility is a major concern for libev. This is why this
		3951	release of libev comes with wrappers for the functions and symbols that
		3952	have been renamed between libev version 3 and 4.
		3953
		3954	You can disable these wrappers (to test compatibility with future
		3955	versions) by defining C<EV_COMPAT3> to C<0> when compiling your
		3956	sources. This has the additional advantage that you can drop the C<struct>
		3957	from C<struct ev_loop> declarations, as libev will provide an C<ev_loop>
		3958	typedef in that case.
		3959
		3960	In some future version, the default for C<EV_COMPAT3> will become C<0>,
		3961	and in some even more future version the compatibility code will be
		3962	removed completely.
		3963
3616	=item EV_STANDALONE	3964	=item EV_STANDALONE (h)
3617		3965
3618	Must always be C<1> if you do not use autoconf configuration, which	3966	Must always be C<1> if you do not use autoconf configuration, which
3619	keeps libev from including F<config.h>, and it also defines dummy	3967	keeps libev from including F<config.h>, and it also defines dummy
3620	implementations for some libevent functions (such as logging, which is not	3968	implementations for some libevent functions (such as logging, which is not
3621	supported). It will also not define any of the structs usually found in	3969	supported). It will also not define any of the structs usually found in
…		…
3771	as well as for signal and thread safety in C<ev_async> watchers.	4119	as well as for signal and thread safety in C<ev_async> watchers.
3772		4120
3773	In the absence of this define, libev will use C<sig_atomic_t volatile>	4121	In the absence of this define, libev will use C<sig_atomic_t volatile>
3774	(from F<signal.h>), which is usually good enough on most platforms.	4122	(from F<signal.h>), which is usually good enough on most platforms.
3775		4123
3776	=item EV_H	4124	=item EV_H (h)
3777		4125
3778	The name of the F<ev.h> header file used to include it. The default if	4126	The name of the F<ev.h> header file used to include it. The default if
3779	undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be	4127	undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be
3780	used to virtually rename the F<ev.h> header file in case of conflicts.	4128	used to virtually rename the F<ev.h> header file in case of conflicts.
3781		4129
3782	=item EV_CONFIG_H	4130	=item EV_CONFIG_H (h)
3783		4131
3784	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override	4132	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override
3785	F<ev.c>'s idea of where to find the F<config.h> file, similarly to	4133	F<ev.c>'s idea of where to find the F<config.h> file, similarly to
3786	C<EV_H>, above.	4134	C<EV_H>, above.
3787		4135
3788	=item EV_EVENT_H	4136	=item EV_EVENT_H (h)
3789		4137
3790	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea	4138	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea
3791	of how the F<event.h> header can be found, the default is C<"event.h">.	4139	of how the F<event.h> header can be found, the default is C<"event.h">.
3792		4140
3793	=item EV_PROTOTYPES	4141	=item EV_PROTOTYPES (h)
3794		4142
3795	If defined to be C<0>, then F<ev.h> will not define any function	4143	If defined to be C<0>, then F<ev.h> will not define any function
3796	prototypes, but still define all the structs and other symbols. This is	4144	prototypes, but still define all the structs and other symbols. This is
3797	occasionally useful if you want to provide your own wrapper functions	4145	occasionally useful if you want to provide your own wrapper functions
3798	around libev functions.	4146	around libev functions.
…		…
3820	fine.	4168	fine.
3821		4169
3822	If your embedding application does not need any priorities, defining these	4170	If your embedding application does not need any priorities, defining these
3823	both to C<0> will save some memory and CPU.	4171	both to C<0> will save some memory and CPU.
3824		4172
3825	=item EV_PERIODIC_ENABLE	4173	=item EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE,
		4174	EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE,
		4175	EV_ASYNC_ENABLE, EV_CHILD_ENABLE.
3826		4176
3827	If undefined or defined to be C<1>, then periodic timers are supported. If	4177	If undefined or defined to be C<1> (and the platform supports it), then
3828	defined to be C<0>, then they are not. Disabling them saves a few kB of	4178	the respective watcher type is supported. If defined to be C<0>, then it
3829	code.	4179	is not. Disabling watcher types mainly saves code size.
3830		4180
3831	=item EV_IDLE_ENABLE	4181	=item EV_FEATURES
3832
3833	If undefined or defined to be C<1>, then idle watchers are supported. If
3834	defined to be C<0>, then they are not. Disabling them saves a few kB of
3835	code.
3836
3837	=item EV_EMBED_ENABLE
3838
3839	If undefined or defined to be C<1>, then embed watchers are supported. If
3840	defined to be C<0>, then they are not. Embed watchers rely on most other
3841	watcher types, which therefore must not be disabled.
3842
3843	=item EV_STAT_ENABLE
3844
3845	If undefined or defined to be C<1>, then stat watchers are supported. If
3846	defined to be C<0>, then they are not.
3847
3848	=item EV_FORK_ENABLE
3849
3850	If undefined or defined to be C<1>, then fork watchers are supported. If
3851	defined to be C<0>, then they are not.
3852
3853	=item EV_ASYNC_ENABLE
3854
3855	If undefined or defined to be C<1>, then async watchers are supported. If
3856	defined to be C<0>, then they are not.
3857
3858	=item EV_MINIMAL
3859		4182
3860	If you need to shave off some kilobytes of code at the expense of some	4183	If you need to shave off some kilobytes of code at the expense of some
3861	speed (but with the full API), define this symbol to C<1>. Currently this	4184	speed (but with the full API), you can define this symbol to request
3862	is used to override some inlining decisions, saves roughly 30% code size	4185	certain subsets of functionality. The default is to enable all features
3863	on amd64. It also selects a much smaller 2-heap for timer management over	4186	that can be enabled on the platform.
3864	the default 4-heap.
3865		4187
3866	You can save even more by disabling watcher types you do not need	4188	A typical way to use this symbol is to define it to C<0> (or to a bitset
3867	and setting C<EV_MAXPRI> == C<EV_MINPRI>. Also, disabling C<assert>	4189	with some broad features you want) and then selectively re-enable
3868	(C<-DNDEBUG>) will usually reduce code size a lot.	4190	additional parts you want, for example if you want everything minimal,
		4191	but multiple event loop support, async and child watchers and the poll
		4192	backend, use this:
3869		4193
3870	Defining C<EV_MINIMAL> to C<2> will additionally reduce the core API to	4194	#define EV_FEATURES 0
3871	provide a bare-bones event library. See C<ev.h> for details on what parts	4195	#define EV_MULTIPLICITY 1
3872	of the API are still available, and do not complain if this subset changes	4196	#define EV_USE_POLL 1
3873	over time.	4197	#define EV_CHILD_ENABLE 1
		4198	#define EV_ASYNC_ENABLE 1
		4199
		4200	The actual value is a bitset, it can be a combination of the following
		4201	values:
		4202
		4203	=over 4
		4204
		4205	=item C<1> - faster/larger code
		4206
		4207	Use larger code to speed up some operations.
		4208
		4209	Currently this is used to override some inlining decisions (enlarging the
		4210	code size by roughly 30% on amd64).
		4211
		4212	When optimising for size, use of compiler flags such as C<-Os> with
		4213	gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of
		4214	assertions.
		4215
		4216	=item C<2> - faster/larger data structures
		4217
		4218	Replaces the small 2-heap for timer management by a faster 4-heap, larger
		4219	hash table sizes and so on. This will usually further increase code size
		4220	and can additionally have an effect on the size of data structures at
		4221	runtime.
		4222
		4223	=item C<4> - full API configuration
		4224
		4225	This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and
		4226	enables multiplicity (C<EV_MULTIPLICITY>=1).
		4227
		4228	=item C<8> - full API
		4229
		4230	This enables a lot of the "lesser used" API functions. See C<ev.h> for
		4231	details on which parts of the API are still available without this
		4232	feature, and do not complain if this subset changes over time.
		4233
		4234	=item C<16> - enable all optional watcher types
		4235
		4236	Enables all optional watcher types. If you want to selectively enable
		4237	only some watcher types other than I/O and timers (e.g. prepare,
		4238	embed, async, child...) you can enable them manually by defining
		4239	C<EV_watchertype_ENABLE> to C<1> instead.
		4240
		4241	=item C<32> - enable all backends
		4242
		4243	This enables all backends - without this feature, you need to enable at
		4244	least one backend manually (C<EV_USE_SELECT> is a good choice).
		4245
		4246	=item C<64> - enable OS-specific "helper" APIs
		4247
		4248	Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by
		4249	default.
		4250
		4251	=back
		4252
		4253	Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0>
		4254	reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb
		4255	code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O
		4256	watchers, timers and monotonic clock support.
		4257
		4258	With an intelligent-enough linker (gcc+binutils are intelligent enough
		4259	when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by
		4260	your program might be left out as well - a binary starting a timer and an
		4261	I/O watcher then might come out at only 5Kb.
		4262
		4263	=item EV_AVOID_STDIO
		4264
		4265	If this is set to C<1> at compiletime, then libev will avoid using stdio
		4266	functions (printf, scanf, perror etc.). This will increase the code size
		4267	somewhat, but if your program doesn't otherwise depend on stdio and your
		4268	libc allows it, this avoids linking in the stdio library which is quite
		4269	big.
		4270
		4271	Note that error messages might become less precise when this option is
		4272	enabled.
3874		4273
3875	=item EV_NSIG	4274	=item EV_NSIG
3876		4275
3877	The highest supported signal number, +1 (or, the number of	4276	The highest supported signal number, +1 (or, the number of
3878	signals): Normally, libev tries to deduce the maximum number of signals	4277	signals): Normally, libev tries to deduce the maximum number of signals
3879	automatically, but sometimes this fails, in which case it can be	4278	automatically, but sometimes this fails, in which case it can be
3880	specified. Also, using a lower number than detected (C<32> should be	4279	specified. Also, using a lower number than detected (C<32> should be
3881	good for about any system in existance) can save some memory, as libev	4280	good for about any system in existence) can save some memory, as libev
3882	statically allocates some 12-24 bytes per signal number.	4281	statically allocates some 12-24 bytes per signal number.
3883		4282
3884	=item EV_PID_HASHSIZE	4283	=item EV_PID_HASHSIZE
3885		4284
3886	C<ev_child> watchers use a small hash table to distribute workload by	4285	C<ev_child> watchers use a small hash table to distribute workload by
3887	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more	4286	pid. The default size is C<16> (or C<1> with C<EV_FEATURES> disabled),
3888	than enough. If you need to manage thousands of children you might want to	4287	usually more than enough. If you need to manage thousands of children you
3889	increase this value (I<must> be a power of two).	4288	might want to increase this value (I<must> be a power of two).
3890		4289
3891	=item EV_INOTIFY_HASHSIZE	4290	=item EV_INOTIFY_HASHSIZE
3892		4291
3893	C<ev_stat> watchers use a small hash table to distribute workload by	4292	C<ev_stat> watchers use a small hash table to distribute workload by
3894	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),	4293	inotify watch id. The default size is C<16> (or C<1> with C<EV_FEATURES>
3895	usually more than enough. If you need to manage thousands of C<ev_stat>	4294	disabled), usually more than enough. If you need to manage thousands of
3896	watchers you might want to increase this value (I<must> be a power of	4295	C<ev_stat> watchers you might want to increase this value (I<must> be a
3897	two).	4296	power of two).
3898		4297
3899	=item EV_USE_4HEAP	4298	=item EV_USE_4HEAP
3900		4299
3901	Heaps are not very cache-efficient. To improve the cache-efficiency of the	4300	Heaps are not very cache-efficient. To improve the cache-efficiency of the
3902	timer and periodics heaps, libev uses a 4-heap when this symbol is defined	4301	timer and periodics heaps, libev uses a 4-heap when this symbol is defined
3903	to C<1>. The 4-heap uses more complicated (longer) code but has noticeably	4302	to C<1>. The 4-heap uses more complicated (longer) code but has noticeably
3904	faster performance with many (thousands) of watchers.	4303	faster performance with many (thousands) of watchers.
3905		4304
3906	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>	4305	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3907	(disabled).	4306	will be C<0>.
3908		4307
3909	=item EV_HEAP_CACHE_AT	4308	=item EV_HEAP_CACHE_AT
3910		4309
3911	Heaps are not very cache-efficient. To improve the cache-efficiency of the	4310	Heaps are not very cache-efficient. To improve the cache-efficiency of the
3912	timer and periodics heaps, libev can cache the timestamp (I<at>) within	4311	timer and periodics heaps, libev can cache the timestamp (I<at>) within
3913	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),	4312	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),
3914	which uses 8-12 bytes more per watcher and a few hundred bytes more code,	4313	which uses 8-12 bytes more per watcher and a few hundred bytes more code,
3915	but avoids random read accesses on heap changes. This improves performance	4314	but avoids random read accesses on heap changes. This improves performance
3916	noticeably with many (hundreds) of watchers.	4315	noticeably with many (hundreds) of watchers.
3917		4316
3918	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>	4317	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3919	(disabled).	4318	will be C<0>.
3920		4319
3921	=item EV_VERIFY	4320	=item EV_VERIFY
3922		4321
3923	Controls how much internal verification (see C<ev_loop_verify ()>) will	4322	Controls how much internal verification (see C<ev_verify ()>) will
3924	be done: If set to C<0>, no internal verification code will be compiled	4323	be done: If set to C<0>, no internal verification code will be compiled
3925	in. If set to C<1>, then verification code will be compiled in, but not	4324	in. If set to C<1>, then verification code will be compiled in, but not
3926	called. If set to C<2>, then the internal verification code will be	4325	called. If set to C<2>, then the internal verification code will be
3927	called once per loop, which can slow down libev. If set to C<3>, then the	4326	called once per loop, which can slow down libev. If set to C<3>, then the
3928	verification code will be called very frequently, which will slow down	4327	verification code will be called very frequently, which will slow down
3929	libev considerably.	4328	libev considerably.
3930		4329
3931	The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be	4330	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3932	C<0>.	4331	will be C<0>.
3933		4332
3934	=item EV_COMMON	4333	=item EV_COMMON
3935		4334
3936	By default, all watchers have a C<void *data> member. By redefining	4335	By default, all watchers have a C<void *data> member. By redefining
3937	this macro to a something else you can include more and other types of	4336	this macro to something else you can include more and other types of
3938	members. You have to define it each time you include one of the files,	4337	members. You have to define it each time you include one of the files,
3939	though, and it must be identical each time.	4338	though, and it must be identical each time.
3940		4339
3941	For example, the perl EV module uses something like this:	4340	For example, the perl EV module uses something like this:
3942		4341
…		…
3995	file.	4394	file.
3996		4395
3997	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	4396	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
3998	that everybody includes and which overrides some configure choices:	4397	that everybody includes and which overrides some configure choices:
3999		4398
4000	#define EV_MINIMAL 1	4399	#define EV_FEATURES 8
4001	#define EV_USE_POLL 0	4400	#define EV_USE_SELECT 1
4002	#define EV_MULTIPLICITY 0
4003	#define EV_PERIODIC_ENABLE 0	4401	#define EV_PREPARE_ENABLE 1
		4402	#define EV_IDLE_ENABLE 1
4004	#define EV_STAT_ENABLE 0	4403	#define EV_SIGNAL_ENABLE 1
4005	#define EV_FORK_ENABLE 0	4404	#define EV_CHILD_ENABLE 1
		4405	#define EV_USE_STDEXCEPT 0
4006	#define EV_CONFIG_H <config.h>	4406	#define EV_CONFIG_H <config.h>
4007	#define EV_MINPRI 0
4008	#define EV_MAXPRI 0
4009		4407
4010	#include "ev++.h"	4408	#include "ev++.h"
4011		4409
4012	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	4410	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
4013		4411
…		…
4144	userdata *u = ev_userdata (EV_A);	4542	userdata *u = ev_userdata (EV_A);
4145	pthread_mutex_lock (&u->lock);	4543	pthread_mutex_lock (&u->lock);
4146	}	4544	}
4147		4545
4148	The event loop thread first acquires the mutex, and then jumps straight	4546	The event loop thread first acquires the mutex, and then jumps straight
4149	into C<ev_loop>:	4547	into C<ev_run>:
4150		4548
4151	void *	4549	void *
4152	l_run (void *thr_arg)	4550	l_run (void *thr_arg)
4153	{	4551	{
4154	struct ev_loop *loop = (struct ev_loop *)thr_arg;	4552	struct ev_loop *loop = (struct ev_loop *)thr_arg;
4155		4553
4156	l_acquire (EV_A);	4554	l_acquire (EV_A);
4157	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);	4555	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
4158	ev_loop (EV_A_ 0);	4556	ev_run (EV_A_ 0);
4159	l_release (EV_A);	4557	l_release (EV_A);
4160		4558
4161	return 0;	4559	return 0;
4162	}	4560	}
4163		4561
…		…
4215		4613
4216	=head3 COROUTINES	4614	=head3 COROUTINES
4217		4615
4218	Libev is very accommodating to coroutines ("cooperative threads"):	4616	Libev is very accommodating to coroutines ("cooperative threads"):
4219	libev fully supports nesting calls to its functions from different	4617	libev fully supports nesting calls to its functions from different
4220	coroutines (e.g. you can call C<ev_loop> on the same loop from two	4618	coroutines (e.g. you can call C<ev_run> on the same loop from two
4221	different coroutines, and switch freely between both coroutines running	4619	different coroutines, and switch freely between both coroutines running
4222	the loop, as long as you don't confuse yourself). The only exception is	4620	the loop, as long as you don't confuse yourself). The only exception is
4223	that you must not do this from C<ev_periodic> reschedule callbacks.	4621	that you must not do this from C<ev_periodic> reschedule callbacks.
4224		4622
4225	Care has been taken to ensure that libev does not keep local state inside	4623	Care has been taken to ensure that libev does not keep local state inside
4226	C<ev_loop>, and other calls do not usually allow for coroutine switches as	4624	C<ev_run>, and other calls do not usually allow for coroutine switches as
4227	they do not call any callbacks.	4625	they do not call any callbacks.
4228		4626
4229	=head2 COMPILER WARNINGS	4627	=head2 COMPILER WARNINGS
4230		4628
4231	Depending on your compiler and compiler settings, you might get no or a	4629	Depending on your compiler and compiler settings, you might get no or a
…		…
4242	maintainable.	4640	maintainable.
4243		4641
4244	And of course, some compiler warnings are just plain stupid, or simply	4642	And of course, some compiler warnings are just plain stupid, or simply
4245	wrong (because they don't actually warn about the condition their message	4643	wrong (because they don't actually warn about the condition their message
4246	seems to warn about). For example, certain older gcc versions had some	4644	seems to warn about). For example, certain older gcc versions had some
4247	warnings that resulted an extreme number of false positives. These have	4645	warnings that resulted in an extreme number of false positives. These have
4248	been fixed, but some people still insist on making code warn-free with	4646	been fixed, but some people still insist on making code warn-free with
4249	such buggy versions.	4647	such buggy versions.
4250		4648
4251	While libev is written to generate as few warnings as possible,	4649	While libev is written to generate as few warnings as possible,
4252	"warn-free" code is not a goal, and it is recommended not to build libev	4650	"warn-free" code is not a goal, and it is recommended not to build libev
…		…
4288	I suggest using suppression lists.	4686	I suggest using suppression lists.
4289		4687
4290		4688
4291	=head1 PORTABILITY NOTES	4689	=head1 PORTABILITY NOTES
4292		4690
		4691	=head2 GNU/LINUX 32 BIT LIMITATIONS
		4692
		4693	GNU/Linux is the only common platform that supports 64 bit file/large file
		4694	interfaces but I<disables> them by default.
		4695
		4696	That means that libev compiled in the default environment doesn't support
		4697	files larger than 2GiB or so, which mainly affects C<ev_stat> watchers.
		4698
		4699	Unfortunately, many programs try to work around this GNU/Linux issue
		4700	by enabling the large file API, which makes them incompatible with the
		4701	standard libev compiled for their system.
		4702
		4703	Likewise, libev cannot enable the large file API itself as this would
		4704	suddenly make it incompatible to the default compile time environment,
		4705	i.e. all programs not using special compile switches.
		4706
		4707	=head2 OS/X AND DARWIN BUGS
		4708
		4709	The whole thing is a bug if you ask me - basically any system interface
		4710	you touch is broken, whether it is locales, poll, kqueue or even the
		4711	OpenGL drivers.
		4712
		4713	=head3 C<kqueue> is buggy
		4714
		4715	The kqueue syscall is broken in all known versions - most versions support
		4716	only sockets, many support pipes.
		4717
		4718	Libev tries to work around this by not using C<kqueue> by default on this
		4719	rotten platform, but of course you can still ask for it when creating a
		4720	loop - embedding a socket-only kqueue loop into a select-based one is
		4721	probably going to work well.
		4722
		4723	=head3 C<poll> is buggy
		4724
		4725	Instead of fixing C<kqueue>, Apple replaced their (working) C<poll>
		4726	implementation by something calling C<kqueue> internally around the 10.5.6
		4727	release, so now C<kqueue> I<and> C<poll> are broken.
		4728
		4729	Libev tries to work around this by not using C<poll> by default on
		4730	this rotten platform, but of course you can still ask for it when creating
		4731	a loop.
		4732
		4733	=head3 C<select> is buggy
		4734
		4735	All that's left is C<select>, and of course Apple found a way to fuck this
		4736	one up as well: On OS/X, C<select> actively limits the number of file
		4737	descriptors you can pass in to 1024 - your program suddenly crashes when
		4738	you use more.
		4739
		4740	There is an undocumented "workaround" for this - defining
		4741	C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should>
		4742	work on OS/X.
		4743
		4744	=head2 SOLARIS PROBLEMS AND WORKAROUNDS
		4745
		4746	=head3 C<errno> reentrancy
		4747
		4748	The default compile environment on Solaris is unfortunately so
		4749	thread-unsafe that you can't even use components/libraries compiled
		4750	without C<-D_REENTRANT> in a threaded program, which, of course, isn't
		4751	defined by default. A valid, if stupid, implementation choice.
		4752
		4753	If you want to use libev in threaded environments you have to make sure
		4754	it's compiled with C<_REENTRANT> defined.
		4755
		4756	=head3 Event port backend
		4757
		4758	The scalable event interface for Solaris is called "event
		4759	ports". Unfortunately, this mechanism is very buggy in all major
		4760	releases. If you run into high CPU usage, your program freezes or you get
		4761	a large number of spurious wakeups, make sure you have all the relevant
		4762	and latest kernel patches applied. No, I don't know which ones, but there
		4763	are multiple ones to apply, and afterwards, event ports actually work
		4764	great.
		4765
		4766	If you can't get it to work, you can try running the program by setting
		4767	the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and
		4768	C<select> backends.
		4769
		4770	=head2 AIX POLL BUG
		4771
		4772	AIX unfortunately has a broken C<poll.h> header. Libev works around
		4773	this by trying to avoid the poll backend altogether (i.e. it's not even
		4774	compiled in), which normally isn't a big problem as C<select> works fine
		4775	with large bitsets on AIX, and AIX is dead anyway.
		4776
4293	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS	4777	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
		4778
		4779	=head3 General issues
4294		4780
4295	Win32 doesn't support any of the standards (e.g. POSIX) that libev	4781	Win32 doesn't support any of the standards (e.g. POSIX) that libev
4296	requires, and its I/O model is fundamentally incompatible with the POSIX	4782	requires, and its I/O model is fundamentally incompatible with the POSIX
4297	model. Libev still offers limited functionality on this platform in	4783	model. Libev still offers limited functionality on this platform in
4298	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	4784	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
4299	descriptors. This only applies when using Win32 natively, not when using	4785	descriptors. This only applies when using Win32 natively, not when using
4300	e.g. cygwin.	4786	e.g. cygwin. Actually, it only applies to the microsofts own compilers,
		4787	as every compielr comes with a slightly differently broken/incompatible
		4788	environment.
4301		4789
4302	Lifting these limitations would basically require the full	4790	Lifting these limitations would basically require the full
4303	re-implementation of the I/O system. If you are into these kinds of	4791	re-implementation of the I/O system. If you are into this kind of thing,
4304	things, then note that glib does exactly that for you in a very portable	4792	then note that glib does exactly that for you in a very portable way (note
4305	way (note also that glib is the slowest event library known to man).	4793	also that glib is the slowest event library known to man).
4306		4794
4307	There is no supported compilation method available on windows except	4795	There is no supported compilation method available on windows except
4308	embedding it into other applications.	4796	embedding it into other applications.
4309		4797
4310	Sensible signal handling is officially unsupported by Microsoft - libev	4798	Sensible signal handling is officially unsupported by Microsoft - libev
…		…
4338	you do I<not> compile the F<ev.c> or any other embedded source files!):	4826	you do I<not> compile the F<ev.c> or any other embedded source files!):
4339		4827
4340	#include "evwrap.h"	4828	#include "evwrap.h"
4341	#include "ev.c"	4829	#include "ev.c"
4342		4830
4343	=over 4
4344
4345	=item The winsocket select function	4831	=head3 The winsocket C<select> function
4346		4832
4347	The winsocket C<select> function doesn't follow POSIX in that it	4833	The winsocket C<select> function doesn't follow POSIX in that it
4348	requires socket I<handles> and not socket I<file descriptors> (it is	4834	requires socket I<handles> and not socket I<file descriptors> (it is
4349	also extremely buggy). This makes select very inefficient, and also	4835	also extremely buggy). This makes select very inefficient, and also
4350	requires a mapping from file descriptors to socket handles (the Microsoft	4836	requires a mapping from file descriptors to socket handles (the Microsoft
…		…
4359	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */	4845	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
4360		4846
4361	Note that winsockets handling of fd sets is O(n), so you can easily get a	4847	Note that winsockets handling of fd sets is O(n), so you can easily get a
4362	complexity in the O(n²) range when using win32.	4848	complexity in the O(n²) range when using win32.
4363		4849
4364	=item Limited number of file descriptors	4850	=head3 Limited number of file descriptors
4365		4851
4366	Windows has numerous arbitrary (and low) limits on things.	4852	Windows has numerous arbitrary (and low) limits on things.
4367		4853
4368	Early versions of winsocket's select only supported waiting for a maximum	4854	Early versions of winsocket's select only supported waiting for a maximum
4369	of C<64> handles (probably owning to the fact that all windows kernels	4855	of C<64> handles (probably owning to the fact that all windows kernels
…		…
4384	runtime libraries. This might get you to about C<512> or C<2048> sockets	4870	runtime libraries. This might get you to about C<512> or C<2048> sockets
4385	(depending on windows version and/or the phase of the moon). To get more,	4871	(depending on windows version and/or the phase of the moon). To get more,
4386	you need to wrap all I/O functions and provide your own fd management, but	4872	you need to wrap all I/O functions and provide your own fd management, but
4387	the cost of calling select (O(n²)) will likely make this unworkable.	4873	the cost of calling select (O(n²)) will likely make this unworkable.
4388		4874
4389	=back
4390
4391	=head2 PORTABILITY REQUIREMENTS	4875	=head2 PORTABILITY REQUIREMENTS
4392		4876
4393	In addition to a working ISO-C implementation and of course the	4877	In addition to a working ISO-C implementation and of course the
4394	backend-specific APIs, libev relies on a few additional extensions:	4878	backend-specific APIs, libev relies on a few additional extensions:
4395		4879
…		…
4401	Libev assumes not only that all watcher pointers have the same internal	4885	Libev assumes not only that all watcher pointers have the same internal
4402	structure (guaranteed by POSIX but not by ISO C for example), but it also	4886	structure (guaranteed by POSIX but not by ISO C for example), but it also
4403	assumes that the same (machine) code can be used to call any watcher	4887	assumes that the same (machine) code can be used to call any watcher
4404	callback: The watcher callbacks have different type signatures, but libev	4888	callback: The watcher callbacks have different type signatures, but libev
4405	calls them using an C<ev_watcher *> internally.	4889	calls them using an C<ev_watcher *> internally.
		4890
		4891	=item pointer accesses must be thread-atomic
		4892
		4893	Accessing a pointer value must be atomic, it must both be readable and
		4894	writable in one piece - this is the case on all current architectures.
4406		4895
4407	=item C<sig_atomic_t volatile> must be thread-atomic as well	4896	=item C<sig_atomic_t volatile> must be thread-atomic as well
4408		4897
4409	The type C<sig_atomic_t volatile> (or whatever is defined as	4898	The type C<sig_atomic_t volatile> (or whatever is defined as
4410	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different	4899	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different
…		…
4433	watchers.	4922	watchers.
4434		4923
4435	=item C<double> must hold a time value in seconds with enough accuracy	4924	=item C<double> must hold a time value in seconds with enough accuracy
4436		4925
4437	The type C<double> is used to represent timestamps. It is required to	4926	The type C<double> is used to represent timestamps. It is required to
4438	have at least 51 bits of mantissa (and 9 bits of exponent), which is good	4927	have at least 51 bits of mantissa (and 9 bits of exponent), which is
4439	enough for at least into the year 4000. This requirement is fulfilled by	4928	good enough for at least into the year 4000 with millisecond accuracy
		4929	(the design goal for libev). This requirement is overfulfilled by
4440	implementations implementing IEEE 754, which is basically all existing	4930	implementations using IEEE 754, which is basically all existing ones. With
4441	ones. With IEEE 754 doubles, you get microsecond accuracy until at least	4931	IEEE 754 doubles, you get microsecond accuracy until at least 2200.
4442	2200.
4443		4932
4444	=back	4933	=back
4445		4934
4446	If you know of other additional requirements drop me a note.	4935	If you know of other additional requirements drop me a note.
4447		4936
…		…
4515	involves iterating over all running async watchers or all signal numbers.	5004	involves iterating over all running async watchers or all signal numbers.
4516		5005
4517	=back	5006	=back
4518		5007
4519		5008
		5009	=head1 PORTING FROM LIBEV 3.X TO 4.X
		5010
		5011	The major version 4 introduced some incompatible changes to the API.
		5012
		5013	At the moment, the C<ev.h> header file provides compatibility definitions
		5014	for all changes, so most programs should still compile. The compatibility
		5015	layer might be removed in later versions of libev, so better update to the
		5016	new API early than late.
		5017
		5018	=over 4
		5019
		5020	=item C<EV_COMPAT3> backwards compatibility mechanism
		5021
		5022	The backward compatibility mechanism can be controlled by
		5023	C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING>
		5024	section.
		5025
		5026	=item C<ev_default_destroy> and C<ev_default_fork> have been removed
		5027
		5028	These calls can be replaced easily by their C<ev_loop_xxx> counterparts:
		5029
		5030	ev_loop_destroy (EV_DEFAULT_UC);
		5031	ev_loop_fork (EV_DEFAULT);
		5032
		5033	=item function/symbol renames
		5034
		5035	A number of functions and symbols have been renamed:
		5036
		5037	ev_loop => ev_run
		5038	EVLOOP_NONBLOCK => EVRUN_NOWAIT
		5039	EVLOOP_ONESHOT => EVRUN_ONCE
		5040
		5041	ev_unloop => ev_break
		5042	EVUNLOOP_CANCEL => EVBREAK_CANCEL
		5043	EVUNLOOP_ONE => EVBREAK_ONE
		5044	EVUNLOOP_ALL => EVBREAK_ALL
		5045
		5046	EV_TIMEOUT => EV_TIMER
		5047
		5048	ev_loop_count => ev_iteration
		5049	ev_loop_depth => ev_depth
		5050	ev_loop_verify => ev_verify
		5051
		5052	Most functions working on C<struct ev_loop> objects don't have an
		5053	C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and
		5054	associated constants have been renamed to not collide with the C<struct
		5055	ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme
		5056	as all other watcher types. Note that C<ev_loop_fork> is still called
		5057	C<ev_loop_fork> because it would otherwise clash with the C<ev_fork>
		5058	typedef.
		5059
		5060	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>
		5061
		5062	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different
		5063	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile
		5064	and work, but the library code will of course be larger.
		5065
		5066	=back
		5067
		5068
4520	=head1 GLOSSARY	5069	=head1 GLOSSARY
4521		5070
4522	=over 4	5071	=over 4
4523		5072
4524	=item active	5073	=item active
4525		5074
4526	A watcher is active as long as it has been started (has been attached to	5075	A watcher is active as long as it has been started and not yet stopped.
4527	an event loop) but not yet stopped (disassociated from the event loop).	5076	See L<WATCHER STATES> for details.
4528		5077
4529	=item application	5078	=item application
4530		5079
4531	In this document, an application is whatever is using libev.	5080	In this document, an application is whatever is using libev.
		5081
		5082	=item backend
		5083
		5084	The part of the code dealing with the operating system interfaces.
4532		5085
4533	=item callback	5086	=item callback
4534		5087
4535	The address of a function that is called when some event has been	5088	The address of a function that is called when some event has been
4536	detected. Callbacks are being passed the event loop, the watcher that	5089	detected. Callbacks are being passed the event loop, the watcher that
4537	received the event, and the actual event bitset.	5090	received the event, and the actual event bitset.
4538		5091
4539	=item callback invocation	5092	=item callback/watcher invocation
4540		5093
4541	The act of calling the callback associated with a watcher.	5094	The act of calling the callback associated with a watcher.
4542		5095
4543	=item event	5096	=item event
4544		5097
4545	A change of state of some external event, such as data now being available	5098	A change of state of some external event, such as data now being available
4546	for reading on a file descriptor, time having passed or simply not having	5099	for reading on a file descriptor, time having passed or simply not having
4547	any other events happening anymore.	5100	any other events happening anymore.
4548		5101
4549	In libev, events are represented as single bits (such as C<EV_READ> or	5102	In libev, events are represented as single bits (such as C<EV_READ> or
4550	C<EV_TIMEOUT>).	5103	C<EV_TIMER>).
4551		5104
4552	=item event library	5105	=item event library
4553		5106
4554	A software package implementing an event model and loop.	5107	A software package implementing an event model and loop.
4555		5108
…		…
4563	The model used to describe how an event loop handles and processes	5116	The model used to describe how an event loop handles and processes
4564	watchers and events.	5117	watchers and events.
4565		5118
4566	=item pending	5119	=item pending
4567		5120
4568	A watcher is pending as soon as the corresponding event has been detected,	5121	A watcher is pending as soon as the corresponding event has been
4569	and stops being pending as soon as the watcher will be invoked or its	5122	detected. See L<WATCHER STATES> for details.
4570	pending status is explicitly cleared by the application.
4571
4572	A watcher can be pending, but not active. Stopping a watcher also clears
4573	its pending status.
4574		5123
4575	=item real time	5124	=item real time
4576		5125
4577	The physical time that is observed. It is apparently strictly monotonic :)	5126	The physical time that is observed. It is apparently strictly monotonic :)
4578		5127
…		…
4585	=item watcher	5134	=item watcher
4586		5135
4587	A data structure that describes interest in certain events. Watchers need	5136	A data structure that describes interest in certain events. Watchers need
4588	to be started (attached to an event loop) before they can receive events.	5137	to be started (attached to an event loop) before they can receive events.
4589		5138
4590	=item watcher invocation
4591
4592	The act of calling the callback associated with a watcher.
4593
4594	=back	5139	=back
4595		5140
4596	=head1 AUTHOR	5141	=head1 AUTHOR
4597		5142
4598	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson.	5143	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael
		5144	Magnusson and Emanuele Giaquinta.
4599		5145

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