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Revision 1.300 by sf-exg, Sun Aug 29 16:13:12 2010 UTC vs.
Revision 1.360 by root, Mon Jan 17 12:11:12 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
…		…
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	Familiarity with event based programming techniques in general is assumed	80	Familiarity with event based programming techniques in general is assumed
81	throughout this document.	81	throughout this document.
		82
		83	=head1 WHAT TO READ WHEN IN A HURRY
		84
		85	This manual tries to be very detailed, but unfortunately, this also makes
		86	it very long. If you just want to know the basics of libev, I suggest
		87	reading L<ANATOMY OF A WATCHER>, then the L<EXAMPLE PROGRAM> above and
		88	look up the missing functions in L<GLOBAL FUNCTIONS> and the C<ev_io> and
		89	C<ev_timer> sections in L<WATCHER TYPES>.
82		90
83	=head1 ABOUT LIBEV	91	=head1 ABOUT LIBEV
84		92
85	Libev is an event loop: you register interest in certain events (such as a	93	Libev is an event loop: you register interest in certain events (such as a
86	file descriptor being readable or a timeout occurring), and it will manage	94	file descriptor being readable or a timeout occurring), and it will manage
…		…
124	this argument.	132	this argument.
125		133
126	=head2 TIME REPRESENTATION	134	=head2 TIME REPRESENTATION
127		135
128	Libev represents time as a single floating point number, representing	136	Libev represents time as a single floating point number, representing
129	the (fractional) number of seconds since the (POSIX) epoch (in practise	137	the (fractional) number of seconds since the (POSIX) epoch (in practice
130	somewhere near the beginning of 1970, details are complicated, don't	138	somewhere near the beginning of 1970, details are complicated, don't
131	ask). This type is called C<ev_tstamp>, which is what you should use	139	ask). This type is called C<ev_tstamp>, which is what you should use
132	too. It usually aliases to the C<double> type in C. When you need to do	140	too. It usually aliases to the C<double> type in C. When you need to do
133	any calculations on it, you should treat it as some floating point value.	141	any calculations on it, you should treat it as some floating point value.
134		142
…		…
165		173
166	=item ev_tstamp ev_time ()	174	=item ev_tstamp ev_time ()
167		175
168	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
169	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
170	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>.
171		180
172	=item ev_sleep (ev_tstamp interval)	181	=item ev_sleep (ev_tstamp interval)
173		182
174	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
175	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
…		…
192	as this indicates an incompatible change. Minor versions are usually	201	as this indicates an incompatible change. Minor versions are usually
193	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
194	not a problem.	203	not a problem.
195		204
196	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
197	version (note, however, that this will not detect ABI mismatches :).	206	version (note, however, that this will not detect other ABI mismatches,
		207	such as LFS or reentrancy).
198		208
199	assert (("libev version mismatch",	209	assert (("libev version mismatch",
200	ev_version_major () == EV_VERSION_MAJOR	210	ev_version_major () == EV_VERSION_MAJOR
201	&& ev_version_minor () >= EV_VERSION_MINOR));	211	&& ev_version_minor () >= EV_VERSION_MINOR));
202		212
…		…
213	assert (("sorry, no epoll, no sex",	223	assert (("sorry, no epoll, no sex",
214	ev_supported_backends () & EVBACKEND_EPOLL));	224	ev_supported_backends () & EVBACKEND_EPOLL));
215		225
216	=item unsigned int ev_recommended_backends ()	226	=item unsigned int ev_recommended_backends ()
217		227
218	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
219	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
220	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
221	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
222	(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
223	libev will probe for if you specify no backends explicitly.	234	probe for if you specify no backends explicitly.
224		235
225	=item unsigned int ev_embeddable_backends ()	236	=item unsigned int ev_embeddable_backends ()
226		237
227	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
228	is the theoretical, all-platform, value. To find which backends	239	value is platform-specific but can include backends not available on the
229	might be supported on the current system, you would need to look at	240	current system. To find which embeddable backends might be supported on
230	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for	241	the current system, you would need to look at C<ev_embeddable_backends ()
231	recommended ones.	242	& ev_supported_backends ()>, likewise for recommended ones.
232		243
233	See the description of C<ev_embed> watchers for more info.	244	See the description of C<ev_embed> watchers for more info.
234		245
235	=item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT]	246	=item ev_set_allocator (void *(*cb)(void *ptr, long size))
236		247
237	Sets the allocation function to use (the prototype is similar - the	248	Sets the allocation function to use (the prototype is similar - the
238	semantics are identical to the C<realloc> C89/SuS/POSIX function). It is	249	semantics are identical to the C<realloc> C89/SuS/POSIX function). It is
239	used to allocate and free memory (no surprises here). If it returns zero	250	used to allocate and free memory (no surprises here). If it returns zero
240	when memory needs to be allocated (C<size != 0>), the library might abort	251	when memory needs to be allocated (C<size != 0>), the library might abort
…		…
266	}	277	}
267		278
268	...	279	...
269	ev_set_allocator (persistent_realloc);	280	ev_set_allocator (persistent_realloc);
270		281
271	=item ev_set_syserr_cb (void (*cb)(const char *msg)); [NOT REENTRANT]	282	=item ev_set_syserr_cb (void (*cb)(const char *msg))
272		283
273	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
274	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
275	indicating the system call or subsystem causing the problem. If this	286	indicating the system call or subsystem causing the problem. If this
276	callback is set, then libev will expect it to remedy the situation, no	287	callback is set, then libev will expect it to remedy the situation, no
…		…
288	}	299	}
289		300
290	...	301	...
291	ev_set_syserr_cb (fatal_error);	302	ev_set_syserr_cb (fatal_error);
292		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
293	=back	317	=back
294		318
295	=head1 FUNCTIONS CONTROLLING THE EVENT LOOP	319	=head1 FUNCTIONS CONTROLLING EVENT LOOPS
296		320
297	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
298	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
299	I<function>).	323	libev 3 had an C<ev_loop> function colliding with the struct name).
300		324
301	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
302	supports signals and child events, and dynamically created loops which do	326	supports child process events, and dynamically created event loops which
303	not.	327	do not.
304		328
305	=over 4	329	=over 4
306		330
307	=item struct ev_loop *ev_default_loop (unsigned int flags)	331	=item struct ev_loop *ev_default_loop (unsigned int flags)
308		332
309	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
310	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
311	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
312	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".
313		343
314	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
315	function.	345	function (or via the C<EV_DEFAULT> macro).
316		346
317	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
318	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
319	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).
320		351
321	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,
322	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
323	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
324	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
325	can simply overwrite the C<SIGCHLD> signal handler I<after> calling	356	C<SIGCHLD> signal handler I<after> calling C<ev_default_init>.
326	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.
327		376
328	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
329	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>).
330		379
331	The following flags are supported:	380	The following flags are supported:
…		…
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_SIGNALFD>	424	=item C<EVFLAG_SIGNALFD>
376		425
377	When this flag is specified, then libev will 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 API	427	I<signalfd> API for its C<ev_signal> (and C<ev_child>) watchers. This API
379	delivers signals synchronously, which makes it both faster and might make	428	delivers signals synchronously, which makes it both faster and might make
380	it possible to get the queued signal data. It can also simplify signal	429	it possible to get the queued signal data. It can also simplify signal
381	handling with threads, as long as you properly block signals in your	430	handling with threads, as long as you properly block signals in your
382	threads that are not interested in handling them.	431	threads that are not interested in handling them.
383		432
384	Signalfd will not be used by default as this changes your signal mask, and	433	Signalfd will not be used by default as this changes your signal mask, and
385	there are a lot of shoddy libraries and programs (glib's threadpool for	434	there are a lot of shoddy libraries and programs (glib's threadpool for
386	example) that can't properly initialise their signal masks.	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	It's also required by POSIX in a threaded program, as libev calls
		448	C<sigprocmask>, whose behaviour is officially unspecified.
		449
		450	This flag's behaviour will become the default in future versions of libev.
387		451
388	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	452	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
389		453
390	This is your standard select(2) backend. Not I<completely> standard, as	454	This is your standard select(2) backend. Not I<completely> standard, as
391	libev tries to roll its own fd_set with no limits on the number of fds,	455	libev tries to roll its own fd_set with no limits on the number of fds,
…		…
427	epoll scales either O(1) or O(active_fds).	491	epoll scales either O(1) or O(active_fds).
428		492
429	The epoll mechanism deserves honorable mention as the most misdesigned	493	The epoll mechanism deserves honorable mention as the most misdesigned
430	of the more advanced event mechanisms: mere annoyances include silently	494	of the more advanced event mechanisms: mere annoyances include silently
431	dropping file descriptors, requiring a system call per change per file	495	dropping file descriptors, requiring a system call per change per file
432	descriptor (and unnecessary guessing of parameters), problems with dup and	496	descriptor (and unnecessary guessing of parameters), problems with dup,
		497	returning before the timeout value, resulting in additional iterations
		498	(and only giving 5ms accuracy while select on the same platform gives
433	so on. The biggest issue is fork races, however - if a program forks then	499	0.1ms) and so on. The biggest issue is fork races, however - if a program
434	I<both> parent and child process have to recreate the epoll set, which can	500	forks then I<both> parent and child process have to recreate the epoll
435	take considerable time (one syscall per file descriptor) and is of course	501	set, which can take considerable time (one syscall per file descriptor)
436	hard to detect.	502	and is of course hard to detect.
437		503
438	Epoll is also notoriously buggy - embedding epoll fds I<should> work, but	504	Epoll is also notoriously buggy - embedding epoll fds I<should> work, but
439	of course I<doesn't>, and epoll just loves to report events for totally	505	of course I<doesn't>, and epoll just loves to report events for totally
440	I<different> file descriptors (even already closed ones, so one cannot	506	I<different> file descriptors (even already closed ones, so one cannot
441	even remove them from the set) than registered in the set (especially	507	even remove them from the set) than registered in the set (especially
442	on SMP systems). Libev tries to counter these spurious notifications by	508	on SMP systems). Libev tries to counter these spurious notifications by
443	employing an additional generation counter and comparing that against the	509	employing an additional generation counter and comparing that against the
444	events to filter out spurious ones, recreating the set when required.	510	events to filter out spurious ones, recreating the set when required. Last
		511	not least, it also refuses to work with some file descriptors which work
		512	perfectly fine with C<select> (files, many character devices...).
		513
		514	Epoll is truly the train wreck analog among event poll mechanisms,
		515	a frankenpoll, cobbled together in a hurry, no thought to design or
		516	interaction with others.
445		517
446	While stopping, setting and starting an I/O watcher in the same iteration	518	While stopping, setting and starting an I/O watcher in the same iteration
447	will result in some caching, there is still a system call per such	519	will result in some caching, there is still a system call per such
448	incident (because the same I<file descriptor> could point to a different	520	incident (because the same I<file descriptor> could point to a different
449	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed	521	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed
…		…
515	=item C<EVBACKEND_PORT> (value 32, Solaris 10)	587	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
516		588
517	This uses the Solaris 10 event port mechanism. As with everything on Solaris,	589	This uses the Solaris 10 event port mechanism. As with everything on Solaris,
518	it's really slow, but it still scales very well (O(active_fds)).	590	it's really slow, but it still scales very well (O(active_fds)).
519		591
520	Please note that Solaris event ports can deliver a lot of spurious
521	notifications, so you need to use non-blocking I/O or other means to avoid
522	blocking when no data (or space) is available.
523
524	While this backend scales well, it requires one system call per active	592	While this backend scales well, it requires one system call per active
525	file descriptor per loop iteration. For small and medium numbers of file	593	file descriptor per loop iteration. For small and medium numbers of file
526	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend	594	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend
527	might perform better.	595	might perform better.
528		596
529	On the positive side, with the exception of the spurious readiness	597	On the positive side, this backend actually performed fully to
530	notifications, this backend actually performed fully to specification
531	in all tests and is fully embeddable, which is a rare feat among the	598	specification in all tests and is fully embeddable, which is a rare feat
532	OS-specific backends (I vastly prefer correctness over speed hacks).	599	among the OS-specific backends (I vastly prefer correctness over speed
		600	hacks).
		601
		602	On the negative side, the interface is I<bizarre> - so bizarre that
		603	even sun itself gets it wrong in their code examples: The event polling
		604	function sometimes returning events to the caller even though an error
		605	occurred, but with no indication whether it has done so or not (yes, it's
		606	even documented that way) - deadly for edge-triggered interfaces where
		607	you absolutely have to know whether an event occurred or not because you
		608	have to re-arm the watcher.
		609
		610	Fortunately libev seems to be able to work around these idiocies.
533		611
534	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as	612	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as
535	C<EVBACKEND_POLL>.	613	C<EVBACKEND_POLL>.
536		614
537	=item C<EVBACKEND_ALL>	615	=item C<EVBACKEND_ALL>
538		616
539	Try all backends (even potentially broken ones that wouldn't be tried	617	Try all backends (even potentially broken ones that wouldn't be tried
540	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as	618	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as
541	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.	619	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.
542		620
543	It is definitely not recommended to use this flag.	621	It is definitely not recommended to use this flag, use whatever
		622	C<ev_recommended_backends ()> returns, or simply do not specify a backend
		623	at all.
		624
		625	=item C<EVBACKEND_MASK>
		626
		627	Not a backend at all, but a mask to select all backend bits from a
		628	C<flags> value, in case you want to mask out any backends from a flags
		629	value (e.g. when modifying the C<LIBEV_FLAGS> environment variable).
544		630
545	=back	631	=back
546		632
547	If one or more of the backend flags are or'ed into the flags value,	633	If one or more of the backend flags are or'ed into the flags value,
548	then only these backends will be tried (in the reverse order as listed	634	then only these backends will be tried (in the reverse order as listed
549	here). If none are specified, all backends in C<ev_recommended_backends	635	here). If none are specified, all backends in C<ev_recommended_backends
550	()> will be tried.	636	()> will be tried.
551		637
552	Example: This is the most typical usage.
553
554	if (!ev_default_loop (0))
555	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
556
557	Example: Restrict libev to the select and poll backends, and do not allow
558	environment settings to be taken into account:
559
560	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
561
562	Example: Use whatever libev has to offer, but make sure that kqueue is
563	used if available (warning, breaks stuff, best use only with your own
564	private event loop and only if you know the OS supports your types of
565	fds):
566
567	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
568
569	=item struct ev_loop *ev_loop_new (unsigned int flags)
570
571	Similar to C<ev_default_loop>, but always creates a new event loop that is
572	always distinct from the default loop.
573
574	Note that this function I<is> thread-safe, and one common way to use
575	libev with threads is indeed to create one loop per thread, and using the
576	default loop in the "main" or "initial" thread.
577
578	Example: Try to create a event loop that uses epoll and nothing else.	638	Example: Try to create a event loop that uses epoll and nothing else.
579		639
580	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	640	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
581	if (!epoller)	641	if (!epoller)
582	fatal ("no epoll found here, maybe it hides under your chair");	642	fatal ("no epoll found here, maybe it hides under your chair");
583		643
		644	Example: Use whatever libev has to offer, but make sure that kqueue is
		645	used if available.
		646
		647	struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE);
		648
584	=item ev_default_destroy ()	649	=item ev_loop_destroy (loop)
585		650
586	Destroys the default loop (frees all memory and kernel state etc.). None	651	Destroys an event loop object (frees all memory and kernel state
587	of the active event watchers will be stopped in the normal sense, so	652	etc.). None of the active event watchers will be stopped in the normal
588	e.g. C<ev_is_active> might still return true. It is your responsibility to	653	sense, so e.g. C<ev_is_active> might still return true. It is your
589	either stop all watchers cleanly yourself I<before> calling this function,	654	responsibility to either stop all watchers cleanly yourself I<before>
590	or cope with the fact afterwards (which is usually the easiest thing, you	655	calling this function, or cope with the fact afterwards (which is usually
591	can just ignore the watchers and/or C<free ()> them for example).	656	the easiest thing, you can just ignore the watchers and/or C<free ()> them
		657	for example).
592		658
593	Note that certain global state, such as signal state (and installed signal	659	Note that certain global state, such as signal state (and installed signal
594	handlers), will not be freed by this function, and related watchers (such	660	handlers), will not be freed by this function, and related watchers (such
595	as signal and child watchers) would need to be stopped manually.	661	as signal and child watchers) would need to be stopped manually.
596		662
597	In general it is not advisable to call this function except in the	663	This function is normally used on loop objects allocated by
598	rare occasion where you really need to free e.g. the signal handling	664	C<ev_loop_new>, but it can also be used on the default loop returned by
		665	C<ev_default_loop>, in which case it is not thread-safe.
		666
		667	Note that it is not advisable to call this function on the default loop
		668	except in the rare occasion where you really need to free its resources.
599	pipe fds. If you need dynamically allocated loops it is better to use	669	If you need dynamically allocated loops it is better to use C<ev_loop_new>
600	C<ev_loop_new> and C<ev_loop_destroy>.	670	and C<ev_loop_destroy>.
601		671
602	=item ev_loop_destroy (loop)	672	=item ev_loop_fork (loop)
603		673
604	Like C<ev_default_destroy>, but destroys an event loop created by an
605	earlier call to C<ev_loop_new>.
606
607	=item ev_default_fork ()
608
609	This function sets a flag that causes subsequent C<ev_loop> iterations	674	This function sets a flag that causes subsequent C<ev_run> iterations to
610	to reinitialise the kernel state for backends that have one. Despite the	675	reinitialise the kernel state for backends that have one. Despite the
611	name, you can call it anytime, but it makes most sense after forking, in	676	name, you can call it anytime, but it makes most sense after forking, in
612	the child process (or both child and parent, but that again makes little	677	the child process. You I<must> call it (or use C<EVFLAG_FORKCHECK>) in the
613	sense). You I<must> call it in the child before using any of the libev	678	child before resuming or calling C<ev_run>.
614	functions, and it will only take effect at the next C<ev_loop> iteration.
615		679
616	Again, you I<have> to call it on I<any> loop that you want to re-use after	680	Again, you I<have> to call it on I<any> loop that you want to re-use after
617	a fork, I<even if you do not plan to use the loop in the parent>. This is	681	a fork, I<even if you do not plan to use the loop in the parent>. This is
618	because some kernel interfaces *cough* I<kqueue> *cough* do funny things	682	because some kernel interfaces *cough* I<kqueue> *cough* do funny things
619	during fork.	683	during fork.
620		684
621	On the other hand, you only need to call this function in the child	685	On the other hand, you only need to call this function in the child
622	process if and only if you want to use the event loop in the child. If you	686	process if and only if you want to use the event loop in the child. If
623	just fork+exec or create a new loop in the child, you don't have to call	687	you just fork+exec or create a new loop in the child, you don't have to
624	it at all.	688	call it at all (in fact, C<epoll> is so badly broken that it makes a
		689	difference, but libev will usually detect this case on its own and do a
		690	costly reset of the backend).
625		691
626	The function itself is quite fast and it's usually not a problem to call	692	The function itself is quite fast and it's usually not a problem to call
627	it just in case after a fork. To make this easy, the function will fit in	693	it just in case after a fork.
628	quite nicely into a call to C<pthread_atfork>:
629		694
		695	Example: Automate calling C<ev_loop_fork> on the default loop when
		696	using pthreads.
		697
		698	static void
		699	post_fork_child (void)
		700	{
		701	ev_loop_fork (EV_DEFAULT);
		702	}
		703
		704	...
630	pthread_atfork (0, 0, ev_default_fork);	705	pthread_atfork (0, 0, post_fork_child);
631
632	=item ev_loop_fork (loop)
633
634	Like C<ev_default_fork>, but acts on an event loop created by
635	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
636	after fork that you want to re-use in the child, and how you keep track of
637	them is entirely your own problem.
638		706
639	=item int ev_is_default_loop (loop)	707	=item int ev_is_default_loop (loop)
640		708
641	Returns true when the given loop is, in fact, the default loop, and false	709	Returns true when the given loop is, in fact, the default loop, and false
642	otherwise.	710	otherwise.
643		711
644	=item unsigned int ev_iteration (loop)	712	=item unsigned int ev_iteration (loop)
645		713
646	Returns the current iteration count for the loop, which is identical to	714	Returns the current iteration count for the event loop, which is identical
647	the number of times libev did poll for new events. It starts at C<0> and	715	to the number of times libev did poll for new events. It starts at C<0>
648	happily wraps around with enough iterations.	716	and happily wraps around with enough iterations.
649		717
650	This value can sometimes be useful as a generation counter of sorts (it	718	This value can sometimes be useful as a generation counter of sorts (it
651	"ticks" the number of loop iterations), as it roughly corresponds with	719	"ticks" the number of loop iterations), as it roughly corresponds with
652	C<ev_prepare> and C<ev_check> calls - and is incremented between the	720	C<ev_prepare> and C<ev_check> calls - and is incremented between the
653	prepare and check phases.	721	prepare and check phases.
654		722
655	=item unsigned int ev_depth (loop)	723	=item unsigned int ev_depth (loop)
656		724
657	Returns the number of times C<ev_loop> was entered minus the number of	725	Returns the number of times C<ev_run> was entered minus the number of
658	times C<ev_loop> was exited, in other words, the recursion depth.	726	times C<ev_run> was exited normally, in other words, the recursion depth.
659		727
660	Outside C<ev_loop>, this number is zero. In a callback, this number is	728	Outside C<ev_run>, this number is zero. In a callback, this number is
661	C<1>, unless C<ev_loop> was invoked recursively (or from another thread),	729	C<1>, unless C<ev_run> was invoked recursively (or from another thread),
662	in which case it is higher.	730	in which case it is higher.
663		731
664	Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread	732	Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread,
665	etc.), doesn't count as "exit" - consider this as a hint to avoid such	733	throwing an exception etc.), doesn't count as "exit" - consider this
666	ungentleman behaviour unless it's really convenient.	734	as a hint to avoid such ungentleman-like behaviour unless it's really
		735	convenient, in which case it is fully supported.
667		736
668	=item unsigned int ev_backend (loop)	737	=item unsigned int ev_backend (loop)
669		738
670	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	739	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
671	use.	740	use.
…		…
680		749
681	=item ev_now_update (loop)	750	=item ev_now_update (loop)
682		751
683	Establishes the current time by querying the kernel, updating the time	752	Establishes the current time by querying the kernel, updating the time
684	returned by C<ev_now ()> in the progress. This is a costly operation and	753	returned by C<ev_now ()> in the progress. This is a costly operation and
685	is usually done automatically within C<ev_loop ()>.	754	is usually done automatically within C<ev_run ()>.
686		755
687	This function is rarely useful, but when some event callback runs for a	756	This function is rarely useful, but when some event callback runs for a
688	very long time without entering the event loop, updating libev's idea of	757	very long time without entering the event loop, updating libev's idea of
689	the current time is a good idea.	758	the current time is a good idea.
690		759
…		…
692		761
693	=item ev_suspend (loop)	762	=item ev_suspend (loop)
694		763
695	=item ev_resume (loop)	764	=item ev_resume (loop)
696		765
697	These two functions suspend and resume a loop, for use when the loop is	766	These two functions suspend and resume an event loop, for use when the
698	not used for a while and timeouts should not be processed.	767	loop is not used for a while and timeouts should not be processed.
699		768
700	A typical use case would be an interactive program such as a game: When	769	A typical use case would be an interactive program such as a game: When
701	the user presses C<^Z> to suspend the game and resumes it an hour later it	770	the user presses C<^Z> to suspend the game and resumes it an hour later it
702	would be best to handle timeouts as if no time had actually passed while	771	would be best to handle timeouts as if no time had actually passed while
703	the program was suspended. This can be achieved by calling C<ev_suspend>	772	the program was suspended. This can be achieved by calling C<ev_suspend>
…		…
714	without a previous call to C<ev_suspend>.	783	without a previous call to C<ev_suspend>.
715		784
716	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the	785	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the
717	event loop time (see C<ev_now_update>).	786	event loop time (see C<ev_now_update>).
718		787
719	=item ev_loop (loop, int flags)	788	=item ev_run (loop, int flags)
720		789
721	Finally, this is it, the event handler. This function usually is called	790	Finally, this is it, the event handler. This function usually is called
722	after you have initialised all your watchers and you want to start	791	after you have initialised all your watchers and you want to start
723	handling events.	792	handling events. It will ask the operating system for any new events, call
		793	the watcher callbacks, an then repeat the whole process indefinitely: This
		794	is why event loops are called I<loops>.
724		795
725	If the flags argument is specified as C<0>, it will not return until	796	If the flags argument is specified as C<0>, it will keep handling events
726	either no event watchers are active anymore or C<ev_unloop> was called.	797	until either no event watchers are active anymore or C<ev_break> was
		798	called.
727		799
728	Please note that an explicit C<ev_unloop> is usually better than	800	Please note that an explicit C<ev_break> is usually better than
729	relying on all watchers to be stopped when deciding when a program has	801	relying on all watchers to be stopped when deciding when a program has
730	finished (especially in interactive programs), but having a program	802	finished (especially in interactive programs), but having a program
731	that automatically loops as long as it has to and no longer by virtue	803	that automatically loops as long as it has to and no longer by virtue
732	of relying on its watchers stopping correctly, that is truly a thing of	804	of relying on its watchers stopping correctly, that is truly a thing of
733	beauty.	805	beauty.
734		806
		807	This function is also I<mostly> exception-safe - you can break out of
		808	a C<ev_run> call by calling C<longjmp> in a callback, throwing a C++
		809	exception and so on. This does not decrement the C<ev_depth> value, nor
		810	will it clear any outstanding C<EVBREAK_ONE> breaks.
		811
735	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle	812	A flags value of C<EVRUN_NOWAIT> will look for new events, will handle
736	those events and any already outstanding ones, but will not block your	813	those events and any already outstanding ones, but will not wait and
737	process in case there are no events and will return after one iteration of	814	block your process in case there are no events and will return after one
738	the loop.	815	iteration of the loop. This is sometimes useful to poll and handle new
		816	events while doing lengthy calculations, to keep the program responsive.
739		817
740	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if	818	A flags value of C<EVRUN_ONCE> will look for new events (waiting if
741	necessary) and will handle those and any already outstanding ones. It	819	necessary) and will handle those and any already outstanding ones. It
742	will block your process until at least one new event arrives (which could	820	will block your process until at least one new event arrives (which could
743	be an event internal to libev itself, so there is no guarantee that a	821	be an event internal to libev itself, so there is no guarantee that a
744	user-registered callback will be called), and will return after one	822	user-registered callback will be called), and will return after one
745	iteration of the loop.	823	iteration of the loop.
746		824
747	This is useful if you are waiting for some external event in conjunction	825	This is useful if you are waiting for some external event in conjunction
748	with something not expressible using other libev watchers (i.e. "roll your	826	with something not expressible using other libev watchers (i.e. "roll your
749	own C<ev_loop>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is	827	own C<ev_run>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is
750	usually a better approach for this kind of thing.	828	usually a better approach for this kind of thing.
751		829
752	Here are the gory details of what C<ev_loop> does:	830	Here are the gory details of what C<ev_run> does:
753		831
		832	- Increment loop depth.
		833	- Reset the ev_break status.
754	- Before the first iteration, call any pending watchers.	834	- Before the first iteration, call any pending watchers.
		835	LOOP:
755	* If EVFLAG_FORKCHECK was used, check for a fork.	836	- If EVFLAG_FORKCHECK was used, check for a fork.
756	- If a fork was detected (by any means), queue and call all fork watchers.	837	- If a fork was detected (by any means), queue and call all fork watchers.
757	- Queue and call all prepare watchers.	838	- Queue and call all prepare watchers.
		839	- If ev_break was called, goto FINISH.
758	- If we have been forked, detach and recreate the kernel state	840	- If we have been forked, detach and recreate the kernel state
759	as to not disturb the other process.	841	as to not disturb the other process.
760	- Update the kernel state with all outstanding changes.	842	- Update the kernel state with all outstanding changes.
761	- Update the "event loop time" (ev_now ()).	843	- Update the "event loop time" (ev_now ()).
762	- Calculate for how long to sleep or block, if at all	844	- Calculate for how long to sleep or block, if at all
763	(active idle watchers, EVLOOP_NONBLOCK or not having	845	(active idle watchers, EVRUN_NOWAIT or not having
764	any active watchers at all will result in not sleeping).	846	any active watchers at all will result in not sleeping).
765	- Sleep if the I/O and timer collect interval say so.	847	- Sleep if the I/O and timer collect interval say so.
		848	- Increment loop iteration counter.
766	- Block the process, waiting for any events.	849	- Block the process, waiting for any events.
767	- Queue all outstanding I/O (fd) events.	850	- Queue all outstanding I/O (fd) events.
768	- Update the "event loop time" (ev_now ()), and do time jump adjustments.	851	- Update the "event loop time" (ev_now ()), and do time jump adjustments.
769	- Queue all expired timers.	852	- Queue all expired timers.
770	- Queue all expired periodics.	853	- Queue all expired periodics.
771	- Unless any events are pending now, queue all idle watchers.	854	- Queue all idle watchers with priority higher than that of pending events.
772	- Queue all check watchers.	855	- Queue all check watchers.
773	- Call all queued watchers in reverse order (i.e. check watchers first).	856	- Call all queued watchers in reverse order (i.e. check watchers first).
774	Signals and child watchers are implemented as I/O watchers, and will	857	Signals and child watchers are implemented as I/O watchers, and will
775	be handled here by queueing them when their watcher gets executed.	858	be handled here by queueing them when their watcher gets executed.
776	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	859	- If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT
777	were used, or there are no active watchers, return, otherwise	860	were used, or there are no active watchers, goto FINISH, otherwise
778	continue with step *.	861	continue with step LOOP.
		862	FINISH:
		863	- Reset the ev_break status iff it was EVBREAK_ONE.
		864	- Decrement the loop depth.
		865	- Return.
779		866
780	Example: Queue some jobs and then loop until no events are outstanding	867	Example: Queue some jobs and then loop until no events are outstanding
781	anymore.	868	anymore.
782		869
783	... queue jobs here, make sure they register event watchers as long	870	... queue jobs here, make sure they register event watchers as long
784	... as they still have work to do (even an idle watcher will do..)	871	... as they still have work to do (even an idle watcher will do..)
785	ev_loop (my_loop, 0);	872	ev_run (my_loop, 0);
786	... jobs done or somebody called unloop. yeah!	873	... jobs done or somebody called unloop. yeah!
787		874
788	=item ev_unloop (loop, how)	875	=item ev_break (loop, how)
789		876
790	Can be used to make a call to C<ev_loop> return early (but only after it	877	Can be used to make a call to C<ev_run> return early (but only after it
791	has processed all outstanding events). The C<how> argument must be either	878	has processed all outstanding events). The C<how> argument must be either
792	C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or	879	C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or
793	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.	880	C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return.
794		881
795	This "unloop state" will be cleared when entering C<ev_loop> again.	882	This "break state" will be cleared on the next call to C<ev_run>.
796		883
797	It is safe to call C<ev_unloop> from outside any C<ev_loop> calls.	884	It is safe to call C<ev_break> from outside any C<ev_run> calls, too, in
		885	which case it will have no effect.
798		886
799	=item ev_ref (loop)	887	=item ev_ref (loop)
800		888
801	=item ev_unref (loop)	889	=item ev_unref (loop)
802		890
803	Ref/unref can be used to add or remove a reference count on the event	891	Ref/unref can be used to add or remove a reference count on the event
804	loop: Every watcher keeps one reference, and as long as the reference	892	loop: Every watcher keeps one reference, and as long as the reference
805	count is nonzero, C<ev_loop> will not return on its own.	893	count is nonzero, C<ev_run> will not return on its own.
806		894
807	This is useful when you have a watcher that you never intend to	895	This is useful when you have a watcher that you never intend to
808	unregister, but that nevertheless should not keep C<ev_loop> from	896	unregister, but that nevertheless should not keep C<ev_run> from
809	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>	897	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>
810	before stopping it.	898	before stopping it.
811		899
812	As an example, libev itself uses this for its internal signal pipe: It	900	As an example, libev itself uses this for its internal signal pipe: It
813	is not visible to the libev user and should not keep C<ev_loop> from	901	is not visible to the libev user and should not keep C<ev_run> from
814	exiting if no event watchers registered by it are active. It is also an	902	exiting if no event watchers registered by it are active. It is also an
815	excellent way to do this for generic recurring timers or from within	903	excellent way to do this for generic recurring timers or from within
816	third-party libraries. Just remember to I<unref after start> and I<ref	904	third-party libraries. Just remember to I<unref after start> and I<ref
817	before stop> (but only if the watcher wasn't active before, or was active	905	before stop> (but only if the watcher wasn't active before, or was active
818	before, respectively. Note also that libev might stop watchers itself	906	before, respectively. Note also that libev might stop watchers itself
819	(e.g. non-repeating timers) in which case you have to C<ev_ref>	907	(e.g. non-repeating timers) in which case you have to C<ev_ref>
820	in the callback).	908	in the callback).
821		909
822	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	910	Example: Create a signal watcher, but keep it from keeping C<ev_run>
823	running when nothing else is active.	911	running when nothing else is active.
824		912
825	ev_signal exitsig;	913	ev_signal exitsig;
826	ev_signal_init (&exitsig, sig_cb, SIGINT);	914	ev_signal_init (&exitsig, sig_cb, SIGINT);
827	ev_signal_start (loop, &exitsig);	915	ev_signal_start (loop, &exitsig);
828	evf_unref (loop);	916	ev_unref (loop);
829		917
830	Example: For some weird reason, unregister the above signal handler again.	918	Example: For some weird reason, unregister the above signal handler again.
831		919
832	ev_ref (loop);	920	ev_ref (loop);
833	ev_signal_stop (loop, &exitsig);	921	ev_signal_stop (loop, &exitsig);
…		…
890	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);	978	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);
891		979
892	=item ev_invoke_pending (loop)	980	=item ev_invoke_pending (loop)
893		981
894	This call will simply invoke all pending watchers while resetting their	982	This call will simply invoke all pending watchers while resetting their
895	pending state. Normally, C<ev_loop> does this automatically when required,	983	pending state. Normally, C<ev_run> does this automatically when required,
896	but when overriding the invoke callback this call comes handy.	984	but when overriding the invoke callback this call comes handy. This
		985	function can be invoked from a watcher - this can be useful for example
		986	when you want to do some lengthy calculation and want to pass further
		987	event handling to another thread (you still have to make sure only one
		988	thread executes within C<ev_invoke_pending> or C<ev_run> of course).
897		989
898	=item int ev_pending_count (loop)	990	=item int ev_pending_count (loop)
899		991
900	Returns the number of pending watchers - zero indicates that no watchers	992	Returns the number of pending watchers - zero indicates that no watchers
901	are pending.	993	are pending.
902		994
903	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))	995	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))
904		996
905	This overrides the invoke pending functionality of the loop: Instead of	997	This overrides the invoke pending functionality of the loop: Instead of
906	invoking all pending watchers when there are any, C<ev_loop> will call	998	invoking all pending watchers when there are any, C<ev_run> will call
907	this callback instead. This is useful, for example, when you want to	999	this callback instead. This is useful, for example, when you want to
908	invoke the actual watchers inside another context (another thread etc.).	1000	invoke the actual watchers inside another context (another thread etc.).
909		1001
910	If you want to reset the callback, use C<ev_invoke_pending> as new	1002	If you want to reset the callback, use C<ev_invoke_pending> as new
911	callback.	1003	callback.
…		…
914		1006
915	Sometimes you want to share the same loop between multiple threads. This	1007	Sometimes you want to share the same loop between multiple threads. This
916	can be done relatively simply by putting mutex_lock/unlock calls around	1008	can be done relatively simply by putting mutex_lock/unlock calls around
917	each call to a libev function.	1009	each call to a libev function.
918		1010
919	However, C<ev_loop> can run an indefinite time, so it is not feasible to	1011	However, C<ev_run> can run an indefinite time, so it is not feasible
920	wait for it to return. One way around this is to wake up the loop via	1012	to wait for it to return. One way around this is to wake up the event
921	C<ev_unloop> and C<av_async_send>, another way is to set these I<release>	1013	loop via C<ev_break> and C<av_async_send>, another way is to set these
922	and I<acquire> callbacks on the loop.	1014	I<release> and I<acquire> callbacks on the loop.
923		1015
924	When set, then C<release> will be called just before the thread is	1016	When set, then C<release> will be called just before the thread is
925	suspended waiting for new events, and C<acquire> is called just	1017	suspended waiting for new events, and C<acquire> is called just
926	afterwards.	1018	afterwards.
927		1019
…		…
930		1022
931	While event loop modifications are allowed between invocations of	1023	While event loop modifications are allowed between invocations of
932	C<release> and C<acquire> (that's their only purpose after all), no	1024	C<release> and C<acquire> (that's their only purpose after all), no
933	modifications done will affect the event loop, i.e. adding watchers will	1025	modifications done will affect the event loop, i.e. adding watchers will
934	have no effect on the set of file descriptors being watched, or the time	1026	have no effect on the set of file descriptors being watched, or the time
935	waited. Use an C<ev_async> watcher to wake up C<ev_loop> when you want it	1027	waited. Use an C<ev_async> watcher to wake up C<ev_run> when you want it
936	to take note of any changes you made.	1028	to take note of any changes you made.
937		1029
938	In theory, threads executing C<ev_loop> will be async-cancel safe between	1030	In theory, threads executing C<ev_run> will be async-cancel safe between
939	invocations of C<release> and C<acquire>.	1031	invocations of C<release> and C<acquire>.
940		1032
941	See also the locking example in the C<THREADS> section later in this	1033	See also the locking example in the C<THREADS> section later in this
942	document.	1034	document.
943		1035
944	=item ev_set_userdata (loop, void *data)	1036	=item ev_set_userdata (loop, void *data)
945		1037
946	=item ev_userdata (loop)	1038	=item void *ev_userdata (loop)
947		1039
948	Set and retrieve a single C<void *> associated with a loop. When	1040	Set and retrieve a single C<void *> associated with a loop. When
949	C<ev_set_userdata> has never been called, then C<ev_userdata> returns	1041	C<ev_set_userdata> has never been called, then C<ev_userdata> returns
950	C<0.>	1042	C<0>.
951		1043
952	These two functions can be used to associate arbitrary data with a loop,	1044	These two functions can be used to associate arbitrary data with a loop,
953	and are intended solely for the C<invoke_pending_cb>, C<release> and	1045	and are intended solely for the C<invoke_pending_cb>, C<release> and
954	C<acquire> callbacks described above, but of course can be (ab-)used for	1046	C<acquire> callbacks described above, but of course can be (ab-)used for
955	any other purpose as well.	1047	any other purpose as well.
956		1048
957	=item ev_loop_verify (loop)	1049	=item ev_verify (loop)
958		1050
959	This function only does something when C<EV_VERIFY> support has been	1051	This function only does something when C<EV_VERIFY> support has been
960	compiled in, which is the default for non-minimal builds. It tries to go	1052	compiled in, which is the default for non-minimal builds. It tries to go
961	through all internal structures and checks them for validity. If anything	1053	through all internal structures and checks them for validity. If anything
962	is found to be inconsistent, it will print an error message to standard	1054	is found to be inconsistent, it will print an error message to standard
…		…
973		1065
974	In the following description, uppercase C<TYPE> in names stands for the	1066	In the following description, uppercase C<TYPE> in names stands for the
975	watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer	1067	watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer
976	watchers and C<ev_io_start> for I/O watchers.	1068	watchers and C<ev_io_start> for I/O watchers.
977		1069
978	A watcher is a structure that you create and register to record your	1070	A watcher is an opaque structure that you allocate and register to record
979	interest in some event. For instance, if you want to wait for STDIN to	1071	your interest in some event. To make a concrete example, imagine you want
980	become readable, you would create an C<ev_io> watcher for that:	1072	to wait for STDIN to become readable, you would create an C<ev_io> watcher
		1073	for that:
981		1074
982	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)	1075	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)
983	{	1076	{
984	ev_io_stop (w);	1077	ev_io_stop (w);
985	ev_unloop (loop, EVUNLOOP_ALL);	1078	ev_break (loop, EVBREAK_ALL);
986	}	1079	}
987		1080
988	struct ev_loop *loop = ev_default_loop (0);	1081	struct ev_loop *loop = ev_default_loop (0);
989		1082
990	ev_io stdin_watcher;	1083	ev_io stdin_watcher;
991		1084
992	ev_init (&stdin_watcher, my_cb);	1085	ev_init (&stdin_watcher, my_cb);
993	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	1086	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
994	ev_io_start (loop, &stdin_watcher);	1087	ev_io_start (loop, &stdin_watcher);
995		1088
996	ev_loop (loop, 0);	1089	ev_run (loop, 0);
997		1090
998	As you can see, you are responsible for allocating the memory for your	1091	As you can see, you are responsible for allocating the memory for your
999	watcher structures (and it is I<usually> a bad idea to do this on the	1092	watcher structures (and it is I<usually> a bad idea to do this on the
1000	stack).	1093	stack).
1001		1094
1002	Each watcher has an associated watcher structure (called C<struct ev_TYPE>	1095	Each watcher has an associated watcher structure (called C<struct ev_TYPE>
1003	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).	1096	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).
1004		1097
1005	Each watcher structure must be initialised by a call to C<ev_init	1098	Each watcher structure must be initialised by a call to C<ev_init (watcher
1006	(watcher *, callback)>, which expects a callback to be provided. This	1099	*, callback)>, which expects a callback to be provided. This callback is
1007	callback gets invoked each time the event occurs (or, in the case of I/O	1100	invoked each time the event occurs (or, in the case of I/O watchers, each
1008	watchers, each time the event loop detects that the file descriptor given	1101	time the event loop detects that the file descriptor given is readable
1009	is readable and/or writable).	1102	and/or writable).
1010		1103
1011	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>	1104	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>
1012	macro to configure it, with arguments specific to the watcher type. There	1105	macro to configure it, with arguments specific to the watcher type. There
1013	is also a macro to combine initialisation and setting in one call: C<<	1106	is also a macro to combine initialisation and setting in one call: C<<
1014	ev_TYPE_init (watcher *, callback, ...) >>.	1107	ev_TYPE_init (watcher *, callback, ...) >>.
…		…
1065		1158
1066	=item C<EV_PREPARE>	1159	=item C<EV_PREPARE>
1067		1160
1068	=item C<EV_CHECK>	1161	=item C<EV_CHECK>
1069		1162
1070	All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts	1163	All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts
1071	to gather new events, and all C<ev_check> watchers are invoked just after	1164	to gather new events, and all C<ev_check> watchers are invoked just after
1072	C<ev_loop> has gathered them, but before it invokes any callbacks for any	1165	C<ev_run> has gathered them, but before it invokes any callbacks for any
1073	received events. Callbacks of both watcher types can start and stop as	1166	received events. Callbacks of both watcher types can start and stop as
1074	many watchers as they want, and all of them will be taken into account	1167	many watchers as they want, and all of them will be taken into account
1075	(for example, a C<ev_prepare> watcher might start an idle watcher to keep	1168	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
1076	C<ev_loop> from blocking).	1169	C<ev_run> from blocking).
1077		1170
1078	=item C<EV_EMBED>	1171	=item C<EV_EMBED>
1079		1172
1080	The embedded event loop specified in the C<ev_embed> watcher needs attention.	1173	The embedded event loop specified in the C<ev_embed> watcher needs attention.
1081		1174
1082	=item C<EV_FORK>	1175	=item C<EV_FORK>
1083		1176
1084	The event loop has been resumed in the child process after fork (see	1177	The event loop has been resumed in the child process after fork (see
1085	C<ev_fork>).	1178	C<ev_fork>).
		1179
		1180	=item C<EV_CLEANUP>
		1181
		1182	The event loop is about to be destroyed (see C<ev_cleanup>).
1086		1183
1087	=item C<EV_ASYNC>	1184	=item C<EV_ASYNC>
1088		1185
1089	The given async watcher has been asynchronously notified (see C<ev_async>).	1186	The given async watcher has been asynchronously notified (see C<ev_async>).
1090		1187
…		…
1263	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related	1360	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related
1264	functions that do not need a watcher.	1361	functions that do not need a watcher.
1265		1362
1266	=back	1363	=back
1267		1364
		1365	See also the L<ASSOCIATING CUSTOM DATA WITH A WATCHER> and L<BUILDING YOUR
		1366	OWN COMPOSITE WATCHERS> idioms.
1268		1367
1269	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	1368	=head2 WATCHER STATES
1270		1369
1271	Each watcher has, by default, a member C<void *data> that you can change	1370	There are various watcher states mentioned throughout this manual -
1272	and read at any time: libev will completely ignore it. This can be used	1371	active, pending and so on. In this section these states and the rules to
1273	to associate arbitrary data with your watcher. If you need more data and	1372	transition between them will be described in more detail - and while these
1274	don't want to allocate memory and store a pointer to it in that data	1373	rules might look complicated, they usually do "the right thing".
1275	member, you can also "subclass" the watcher type and provide your own
1276	data:
1277		1374
1278	struct my_io	1375	=over 4
1279	{
1280	ev_io io;
1281	int otherfd;
1282	void *somedata;
1283	struct whatever *mostinteresting;
1284	};
1285		1376
1286	...	1377	=item initialiased
1287	struct my_io w;
1288	ev_io_init (&w.io, my_cb, fd, EV_READ);
1289		1378
1290	And since your callback will be called with a pointer to the watcher, you	1379	Before a watcher can be registered with the event looop it has to be
1291	can cast it back to your own type:	1380	initialised. This can be done with a call to C<ev_TYPE_init>, or calls to
		1381	C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function.
1292		1382
1293	static void my_cb (struct ev_loop *loop, ev_io *w_, int revents)	1383	In this state it is simply some block of memory that is suitable for use
1294	{	1384	in an event loop. It can be moved around, freed, reused etc. at will.
1295	struct my_io *w = (struct my_io *)w_;
1296	...
1297	}
1298		1385
1299	More interesting and less C-conformant ways of casting your callback type	1386	=item started/running/active
1300	instead have been omitted.
1301		1387
1302	Another common scenario is to use some data structure with multiple	1388	Once a watcher has been started with a call to C<ev_TYPE_start> it becomes
1303	embedded watchers:	1389	property of the event loop, and is actively waiting for events. While in
		1390	this state it cannot be accessed (except in a few documented ways), moved,
		1391	freed or anything else - the only legal thing is to keep a pointer to it,
		1392	and call libev functions on it that are documented to work on active watchers.
1304		1393
1305	struct my_biggy	1394	=item pending
1306	{
1307	int some_data;
1308	ev_timer t1;
1309	ev_timer t2;
1310	}
1311		1395
1312	In this case getting the pointer to C<my_biggy> is a bit more	1396	If a watcher is active and libev determines that an event it is interested
1313	complicated: Either you store the address of your C<my_biggy> struct	1397	in has occurred (such as a timer expiring), it will become pending. It will
1314	in the C<data> member of the watcher (for woozies), or you need to use	1398	stay in this pending state until either it is stopped or its callback is
1315	some pointer arithmetic using C<offsetof> inside your watchers (for real	1399	about to be invoked, so it is not normally pending inside the watcher
1316	programmers):	1400	callback.
1317		1401
1318	#include <stddef.h>	1402	The watcher might or might not be active while it is pending (for example,
		1403	an expired non-repeating timer can be pending but no longer active). If it
		1404	is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>),
		1405	but it is still property of the event loop at this time, so cannot be
		1406	moved, freed or reused. And if it is active the rules described in the
		1407	previous item still apply.
1319		1408
1320	static void	1409	It is also possible to feed an event on a watcher that is not active (e.g.
1321	t1_cb (EV_P_ ev_timer *w, int revents)	1410	via C<ev_feed_event>), in which case it becomes pending without being
1322	{	1411	active.
1323	struct my_biggy big = (struct my_biggy *)
1324	(((char *)w) - offsetof (struct my_biggy, t1));
1325	}
1326		1412
1327	static void	1413	=item stopped
1328	t2_cb (EV_P_ ev_timer *w, int revents)	1414
1329	{	1415	A watcher can be stopped implicitly by libev (in which case it might still
1330	struct my_biggy big = (struct my_biggy *)	1416	be pending), or explicitly by calling its C<ev_TYPE_stop> function. The
1331	(((char *)w) - offsetof (struct my_biggy, t2));	1417	latter will clear any pending state the watcher might be in, regardless
1332	}	1418	of whether it was active or not, so stopping a watcher explicitly before
		1419	freeing it is often a good idea.
		1420
		1421	While stopped (and not pending) the watcher is essentially in the
		1422	initialised state, that is it can be reused, moved, modified in any way
		1423	you wish.
		1424
		1425	=back
1333		1426
1334	=head2 WATCHER PRIORITY MODELS	1427	=head2 WATCHER PRIORITY MODELS
1335		1428
1336	Many event loops support I<watcher priorities>, which are usually small	1429	Many event loops support I<watcher priorities>, which are usually small
1337	integers that influence the ordering of event callback invocation	1430	integers that influence the ordering of event callback invocation
…		…
1464	In general you can register as many read and/or write event watchers per	1557	In general you can register as many read and/or write event watchers per
1465	fd as you want (as long as you don't confuse yourself). Setting all file	1558	fd as you want (as long as you don't confuse yourself). Setting all file
1466	descriptors to non-blocking mode is also usually a good idea (but not	1559	descriptors to non-blocking mode is also usually a good idea (but not
1467	required if you know what you are doing).	1560	required if you know what you are doing).
1468		1561
1469	If you cannot use non-blocking mode, then force the use of a
1470	known-to-be-good backend (at the time of this writing, this includes only
1471	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file
1472	descriptors for which non-blocking operation makes no sense (such as
1473	files) - libev doesn't guarantee any specific behaviour in that case.
1474
1475	Another thing you have to watch out for is that it is quite easy to	1562	Another thing you have to watch out for is that it is quite easy to
1476	receive "spurious" readiness notifications, that is your callback might	1563	receive "spurious" readiness notifications, that is, your callback might
1477	be called with C<EV_READ> but a subsequent C<read>(2) will actually block	1564	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
1478	because there is no data. Not only are some backends known to create a	1565	because there is no data. It is very easy to get into this situation even
1479	lot of those (for example Solaris ports), it is very easy to get into	1566	with a relatively standard program structure. Thus it is best to always
1480	this situation even with a relatively standard program structure. Thus	1567	use non-blocking I/O: An extra C<read>(2) returning C<EAGAIN> is far
1481	it is best to always use non-blocking I/O: An extra C<read>(2) returning
1482	C<EAGAIN> is far preferable to a program hanging until some data arrives.	1568	preferable to a program hanging until some data arrives.
1483		1569
1484	If you cannot run the fd in non-blocking mode (for example you should	1570	If you cannot run the fd in non-blocking mode (for example you should
1485	not play around with an Xlib connection), then you have to separately	1571	not play around with an Xlib connection), then you have to separately
1486	re-test whether a file descriptor is really ready with a known-to-be good	1572	re-test whether a file descriptor is really ready with a known-to-be good
1487	interface such as poll (fortunately in our Xlib example, Xlib already	1573	interface such as poll (fortunately in the case of Xlib, it already does
1488	does this on its own, so its quite safe to use). Some people additionally	1574	this on its own, so its quite safe to use). Some people additionally
1489	use C<SIGALRM> and an interval timer, just to be sure you won't block	1575	use C<SIGALRM> and an interval timer, just to be sure you won't block
1490	indefinitely.	1576	indefinitely.
1491		1577
1492	But really, best use non-blocking mode.	1578	But really, best use non-blocking mode.
1493		1579
…		…
1521		1607
1522	There is no workaround possible except not registering events	1608	There is no workaround possible except not registering events
1523	for potentially C<dup ()>'ed file descriptors, or to resort to	1609	for potentially C<dup ()>'ed file descriptors, or to resort to
1524	C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>.	1610	C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>.
1525		1611
		1612	=head3 The special problem of files
		1613
		1614	Many people try to use C<select> (or libev) on file descriptors
		1615	representing files, and expect it to become ready when their program
		1616	doesn't block on disk accesses (which can take a long time on their own).
		1617
		1618	However, this cannot ever work in the "expected" way - you get a readiness
		1619	notification as soon as the kernel knows whether and how much data is
		1620	there, and in the case of open files, that's always the case, so you
		1621	always get a readiness notification instantly, and your read (or possibly
		1622	write) will still block on the disk I/O.
		1623
		1624	Another way to view it is that in the case of sockets, pipes, character
		1625	devices and so on, there is another party (the sender) that delivers data
		1626	on its own, but in the case of files, there is no such thing: the disk
		1627	will not send data on its own, simply because it doesn't know what you
		1628	wish to read - you would first have to request some data.
		1629
		1630	Since files are typically not-so-well supported by advanced notification
		1631	mechanism, libev tries hard to emulate POSIX behaviour with respect
		1632	to files, even though you should not use it. The reason for this is
		1633	convenience: sometimes you want to watch STDIN or STDOUT, which is
		1634	usually a tty, often a pipe, but also sometimes files or special devices
		1635	(for example, C<epoll> on Linux works with F</dev/random> but not with
		1636	F</dev/urandom>), and even though the file might better be served with
		1637	asynchronous I/O instead of with non-blocking I/O, it is still useful when
		1638	it "just works" instead of freezing.
		1639
		1640	So avoid file descriptors pointing to files when you know it (e.g. use
		1641	libeio), but use them when it is convenient, e.g. for STDIN/STDOUT, or
		1642	when you rarely read from a file instead of from a socket, and want to
		1643	reuse the same code path.
		1644
1526	=head3 The special problem of fork	1645	=head3 The special problem of fork
1527		1646
1528	Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit	1647	Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit
1529	useless behaviour. Libev fully supports fork, but needs to be told about	1648	useless behaviour. Libev fully supports fork, but needs to be told about
1530	it in the child.	1649	it in the child if you want to continue to use it in the child.
1531		1650
1532	To support fork in your programs, you either have to call	1651	To support fork in your child processes, you have to call C<ev_loop_fork
1533	C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child,	1652	()> after a fork in the child, enable C<EVFLAG_FORKCHECK>, or resort to
1534	enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or	1653	C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>.
1535	C<EVBACKEND_POLL>.
1536		1654
1537	=head3 The special problem of SIGPIPE	1655	=head3 The special problem of SIGPIPE
1538		1656
1539	While not really specific to libev, it is easy to forget about C<SIGPIPE>:	1657	While not really specific to libev, it is easy to forget about C<SIGPIPE>:
1540	when writing to a pipe whose other end has been closed, your program gets	1658	when writing to a pipe whose other end has been closed, your program gets
…		…
1622	...	1740	...
1623	struct ev_loop *loop = ev_default_init (0);	1741	struct ev_loop *loop = ev_default_init (0);
1624	ev_io stdin_readable;	1742	ev_io stdin_readable;
1625	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1743	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1626	ev_io_start (loop, &stdin_readable);	1744	ev_io_start (loop, &stdin_readable);
1627	ev_loop (loop, 0);	1745	ev_run (loop, 0);
1628		1746
1629		1747
1630	=head2 C<ev_timer> - relative and optionally repeating timeouts	1748	=head2 C<ev_timer> - relative and optionally repeating timeouts
1631		1749
1632	Timer watchers are simple relative timers that generate an event after a	1750	Timer watchers are simple relative timers that generate an event after a
…		…
1641	The callback is guaranteed to be invoked only I<after> its timeout has	1759	The callback is guaranteed to be invoked only I<after> its timeout has
1642	passed (not I<at>, so on systems with very low-resolution clocks this	1760	passed (not I<at>, so on systems with very low-resolution clocks this
1643	might introduce a small delay). If multiple timers become ready during the	1761	might introduce a small delay). If multiple timers become ready during the
1644	same loop iteration then the ones with earlier time-out values are invoked	1762	same loop iteration then the ones with earlier time-out values are invoked
1645	before ones of the same priority with later time-out values (but this is	1763	before ones of the same priority with later time-out values (but this is
1646	no longer true when a callback calls C<ev_loop> recursively).	1764	no longer true when a callback calls C<ev_run> recursively).
1647		1765
1648	=head3 Be smart about timeouts	1766	=head3 Be smart about timeouts
1649		1767
1650	Many real-world problems involve some kind of timeout, usually for error	1768	Many real-world problems involve some kind of timeout, usually for error
1651	recovery. A typical example is an HTTP request - if the other side hangs,	1769	recovery. A typical example is an HTTP request - if the other side hangs,
…		…
1822		1940
1823	=head3 The special problem of time updates	1941	=head3 The special problem of time updates
1824		1942
1825	Establishing the current time is a costly operation (it usually takes at	1943	Establishing the current time is a costly operation (it usually takes at
1826	least two system calls): EV therefore updates its idea of the current	1944	least two system calls): EV therefore updates its idea of the current
1827	time only before and after C<ev_loop> collects new events, which causes a	1945	time only before and after C<ev_run> collects new events, which causes a
1828	growing difference between C<ev_now ()> and C<ev_time ()> when handling	1946	growing difference between C<ev_now ()> and C<ev_time ()> when handling
1829	lots of events in one iteration.	1947	lots of events in one iteration.
1830		1948
1831	The relative timeouts are calculated relative to the C<ev_now ()>	1949	The relative timeouts are calculated relative to the C<ev_now ()>
1832	time. This is usually the right thing as this timestamp refers to the time	1950	time. This is usually the right thing as this timestamp refers to the time
…		…
1949	}	2067	}
1950		2068
1951	ev_timer mytimer;	2069	ev_timer mytimer;
1952	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	2070	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1953	ev_timer_again (&mytimer); /* start timer */	2071	ev_timer_again (&mytimer); /* start timer */
1954	ev_loop (loop, 0);	2072	ev_run (loop, 0);
1955		2073
1956	// and in some piece of code that gets executed on any "activity":	2074	// and in some piece of code that gets executed on any "activity":
1957	// reset the timeout to start ticking again at 10 seconds	2075	// reset the timeout to start ticking again at 10 seconds
1958	ev_timer_again (&mytimer);	2076	ev_timer_again (&mytimer);
1959		2077
…		…
1985		2103
1986	As with timers, the callback is guaranteed to be invoked only when the	2104	As with timers, the callback is guaranteed to be invoked only when the
1987	point in time where it is supposed to trigger has passed. If multiple	2105	point in time where it is supposed to trigger has passed. If multiple
1988	timers become ready during the same loop iteration then the ones with	2106	timers become ready during the same loop iteration then the ones with
1989	earlier time-out values are invoked before ones with later time-out values	2107	earlier time-out values are invoked before ones with later time-out values
1990	(but this is no longer true when a callback calls C<ev_loop> recursively).	2108	(but this is no longer true when a callback calls C<ev_run> recursively).
1991		2109
1992	=head3 Watcher-Specific Functions and Data Members	2110	=head3 Watcher-Specific Functions and Data Members
1993		2111
1994	=over 4	2112	=over 4
1995		2113
…		…
2123	Example: Call a callback every hour, or, more precisely, whenever the	2241	Example: Call a callback every hour, or, more precisely, whenever the
2124	system time is divisible by 3600. The callback invocation times have	2242	system time is divisible by 3600. The callback invocation times have
2125	potentially a lot of jitter, but good long-term stability.	2243	potentially a lot of jitter, but good long-term stability.
2126		2244
2127	static void	2245	static void
2128	clock_cb (struct ev_loop *loop, ev_io *w, int revents)	2246	clock_cb (struct ev_loop *loop, ev_periodic *w, int revents)
2129	{	2247	{
2130	... its now a full hour (UTC, or TAI or whatever your clock follows)	2248	... its now a full hour (UTC, or TAI or whatever your clock follows)
2131	}	2249	}
2132		2250
2133	ev_periodic hourly_tick;	2251	ev_periodic hourly_tick;
…		…
2156		2274
2157	=head2 C<ev_signal> - signal me when a signal gets signalled!	2275	=head2 C<ev_signal> - signal me when a signal gets signalled!
2158		2276
2159	Signal watchers will trigger an event when the process receives a specific	2277	Signal watchers will trigger an event when the process receives a specific
2160	signal one or more times. Even though signals are very asynchronous, libev	2278	signal one or more times. Even though signals are very asynchronous, libev
2161	will try it's best to deliver signals synchronously, i.e. as part of the	2279	will try its best to deliver signals synchronously, i.e. as part of the
2162	normal event processing, like any other event.	2280	normal event processing, like any other event.
2163		2281
2164	If you want signals to be delivered truly asynchronously, just use	2282	If you want signals to be delivered truly asynchronously, just use
2165	C<sigaction> as you would do without libev and forget about sharing	2283	C<sigaction> as you would do without libev and forget about sharing
2166	the signal. You can even use C<ev_async> from a signal handler to	2284	the signal. You can even use C<ev_async> from a signal handler to
…		…
2185	=head3 The special problem of inheritance over fork/execve/pthread_create	2303	=head3 The special problem of inheritance over fork/execve/pthread_create
2186		2304
2187	Both the signal mask (C<sigprocmask>) and the signal disposition	2305	Both the signal mask (C<sigprocmask>) and the signal disposition
2188	(C<sigaction>) are unspecified after starting a signal watcher (and after	2306	(C<sigaction>) are unspecified after starting a signal watcher (and after
2189	stopping it again), that is, libev might or might not block the signal,	2307	stopping it again), that is, libev might or might not block the signal,
2190	and might or might not set or restore the installed signal handler.	2308	and might or might not set or restore the installed signal handler (but
		2309	see C<EVFLAG_NOSIGMASK>).
2191		2310
2192	While this does not matter for the signal disposition (libev never	2311	While this does not matter for the signal disposition (libev never
2193	sets signals to C<SIG_IGN>, so handlers will be reset to C<SIG_DFL> on	2312	sets signals to C<SIG_IGN>, so handlers will be reset to C<SIG_DFL> on
2194	C<execve>), this matters for the signal mask: many programs do not expect	2313	C<execve>), this matters for the signal mask: many programs do not expect
2195	certain signals to be blocked.	2314	certain signals to be blocked.
…		…
2209		2328
2210	So I can't stress this enough: I<If you do not reset your signal mask when	2329	So I can't stress this enough: I<If you do not reset your signal mask when
2211	you expect it to be empty, you have a race condition in your code>. This	2330	you expect it to be empty, you have a race condition in your code>. This
2212	is not a libev-specific thing, this is true for most event libraries.	2331	is not a libev-specific thing, this is true for most event libraries.
2213		2332
		2333	=head3 The special problem of threads signal handling
		2334
		2335	POSIX threads has problematic signal handling semantics, specifically,
		2336	a lot of functionality (sigfd, sigwait etc.) only really works if all
		2337	threads in a process block signals, which is hard to achieve.
		2338
		2339	When you want to use sigwait (or mix libev signal handling with your own
		2340	for the same signals), you can tackle this problem by globally blocking
		2341	all signals before creating any threads (or creating them with a fully set
		2342	sigprocmask) and also specifying the C<EVFLAG_NOSIGMASK> when creating
		2343	loops. Then designate one thread as "signal receiver thread" which handles
		2344	these signals. You can pass on any signals that libev might be interested
		2345	in by calling C<ev_feed_signal>.
		2346
2214	=head3 Watcher-Specific Functions and Data Members	2347	=head3 Watcher-Specific Functions and Data Members
2215		2348
2216	=over 4	2349	=over 4
2217		2350
2218	=item ev_signal_init (ev_signal *, callback, int signum)	2351	=item ev_signal_init (ev_signal *, callback, int signum)
…		…
2233	Example: Try to exit cleanly on SIGINT.	2366	Example: Try to exit cleanly on SIGINT.
2234		2367
2235	static void	2368	static void
2236	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)	2369	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)
2237	{	2370	{
2238	ev_unloop (loop, EVUNLOOP_ALL);	2371	ev_break (loop, EVBREAK_ALL);
2239	}	2372	}
2240		2373
2241	ev_signal signal_watcher;	2374	ev_signal signal_watcher;
2242	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	2375	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
2243	ev_signal_start (loop, &signal_watcher);	2376	ev_signal_start (loop, &signal_watcher);
…		…
2629		2762
2630	Prepare and check watchers are usually (but not always) used in pairs:	2763	Prepare and check watchers are usually (but not always) used in pairs:
2631	prepare watchers get invoked before the process blocks and check watchers	2764	prepare watchers get invoked before the process blocks and check watchers
2632	afterwards.	2765	afterwards.
2633		2766
2634	You I<must not> call C<ev_loop> or similar functions that enter	2767	You I<must not> call C<ev_run> or similar functions that enter
2635	the current event loop from either C<ev_prepare> or C<ev_check>	2768	the current event loop from either C<ev_prepare> or C<ev_check>
2636	watchers. Other loops than the current one are fine, however. The	2769	watchers. Other loops than the current one are fine, however. The
2637	rationale behind this is that you do not need to check for recursion in	2770	rationale behind this is that you do not need to check for recursion in
2638	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,	2771	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,
2639	C<ev_check> so if you have one watcher of each kind they will always be	2772	C<ev_check> so if you have one watcher of each kind they will always be
…		…
2807		2940
2808	if (timeout >= 0)	2941	if (timeout >= 0)
2809	// create/start timer	2942	// create/start timer
2810		2943
2811	// poll	2944	// poll
2812	ev_loop (EV_A_ 0);	2945	ev_run (EV_A_ 0);
2813		2946
2814	// stop timer again	2947	// stop timer again
2815	if (timeout >= 0)	2948	if (timeout >= 0)
2816	ev_timer_stop (EV_A_ &to);	2949	ev_timer_stop (EV_A_ &to);
2817		2950
…		…
2895	if you do not want that, you need to temporarily stop the embed watcher).	3028	if you do not want that, you need to temporarily stop the embed watcher).
2896		3029
2897	=item ev_embed_sweep (loop, ev_embed *)	3030	=item ev_embed_sweep (loop, ev_embed *)
2898		3031
2899	Make a single, non-blocking sweep over the embedded loop. This works	3032	Make a single, non-blocking sweep over the embedded loop. This works
2900	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	3033	similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most
2901	appropriate way for embedded loops.	3034	appropriate way for embedded loops.
2902		3035
2903	=item struct ev_loop *other [read-only]	3036	=item struct ev_loop *other [read-only]
2904		3037
2905	The embedded event loop.	3038	The embedded event loop.
…		…
2965	C<ev_default_fork> cheats and calls it in the wrong process, the fork	3098	C<ev_default_fork> cheats and calls it in the wrong process, the fork
2966	handlers will be invoked, too, of course.	3099	handlers will be invoked, too, of course.
2967		3100
2968	=head3 The special problem of life after fork - how is it possible?	3101	=head3 The special problem of life after fork - how is it possible?
2969		3102
2970	Most uses of C<fork()> consist of forking, then some simple calls to ste	3103	Most uses of C<fork()> consist of forking, then some simple calls to set
2971	up/change the process environment, followed by a call to C<exec()>. This	3104	up/change the process environment, followed by a call to C<exec()>. This
2972	sequence should be handled by libev without any problems.	3105	sequence should be handled by libev without any problems.
2973		3106
2974	This changes when the application actually wants to do event handling	3107	This changes when the application actually wants to do event handling
2975	in the child, or both parent in child, in effect "continuing" after the	3108	in the child, or both parent in child, in effect "continuing" after the
…		…
2991	disadvantage of having to use multiple event loops (which do not support	3124	disadvantage of having to use multiple event loops (which do not support
2992	signal watchers).	3125	signal watchers).
2993		3126
2994	When this is not possible, or you want to use the default loop for	3127	When this is not possible, or you want to use the default loop for
2995	other reasons, then in the process that wants to start "fresh", call	3128	other reasons, then in the process that wants to start "fresh", call
2996	C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying	3129	C<ev_loop_destroy (EV_DEFAULT)> followed by C<ev_default_loop (...)>.
2997	the default loop will "orphan" (not stop) all registered watchers, so you	3130	Destroying the default loop will "orphan" (not stop) all registered
2998	have to be careful not to execute code that modifies those watchers. Note	3131	watchers, so you have to be careful not to execute code that modifies
2999	also that in that case, you have to re-register any signal watchers.	3132	those watchers. Note also that in that case, you have to re-register any
		3133	signal watchers.
3000		3134
3001	=head3 Watcher-Specific Functions and Data Members	3135	=head3 Watcher-Specific Functions and Data Members
3002		3136
3003	=over 4	3137	=over 4
3004		3138
3005	=item ev_fork_init (ev_signal *, callback)	3139	=item ev_fork_init (ev_fork *, callback)
3006		3140
3007	Initialises and configures the fork watcher - it has no parameters of any	3141	Initialises and configures the fork watcher - it has no parameters of any
3008	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,	3142	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
3009	believe me.	3143	really.
3010		3144
3011	=back	3145	=back
3012		3146
3013		3147
		3148	=head2 C<ev_cleanup> - even the best things end
		3149
		3150	Cleanup watchers are called just before the event loop is being destroyed
		3151	by a call to C<ev_loop_destroy>.
		3152
		3153	While there is no guarantee that the event loop gets destroyed, cleanup
		3154	watchers provide a convenient method to install cleanup hooks for your
		3155	program, worker threads and so on - you just to make sure to destroy the
		3156	loop when you want them to be invoked.
		3157
		3158	Cleanup watchers are invoked in the same way as any other watcher. Unlike
		3159	all other watchers, they do not keep a reference to the event loop (which
		3160	makes a lot of sense if you think about it). Like all other watchers, you
		3161	can call libev functions in the callback, except C<ev_cleanup_start>.
		3162
		3163	=head3 Watcher-Specific Functions and Data Members
		3164
		3165	=over 4
		3166
		3167	=item ev_cleanup_init (ev_cleanup *, callback)
		3168
		3169	Initialises and configures the cleanup watcher - it has no parameters of
		3170	any kind. There is a C<ev_cleanup_set> macro, but using it is utterly
		3171	pointless, I assure you.
		3172
		3173	=back
		3174
		3175	Example: Register an atexit handler to destroy the default loop, so any
		3176	cleanup functions are called.
		3177
		3178	static void
		3179	program_exits (void)
		3180	{
		3181	ev_loop_destroy (EV_DEFAULT_UC);
		3182	}
		3183
		3184	...
		3185	atexit (program_exits);
		3186
		3187
3014	=head2 C<ev_async> - how to wake up another event loop	3188	=head2 C<ev_async> - how to wake up an event loop
3015		3189
3016	In general, you cannot use an C<ev_loop> from multiple threads or other	3190	In general, you cannot use an C<ev_run> from multiple threads or other
3017	asynchronous sources such as signal handlers (as opposed to multiple event	3191	asynchronous sources such as signal handlers (as opposed to multiple event
3018	loops - those are of course safe to use in different threads).	3192	loops - those are of course safe to use in different threads).
3019		3193
3020	Sometimes, however, you need to wake up another event loop you do not	3194	Sometimes, however, you need to wake up an event loop you do not control,
3021	control, for example because it belongs to another thread. This is what	3195	for example because it belongs to another thread. This is what C<ev_async>
3022	C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you	3196	watchers do: as long as the C<ev_async> watcher is active, you can signal
3023	can signal it by calling C<ev_async_send>, which is thread- and signal	3197	it by calling C<ev_async_send>, which is thread- and signal safe.
3024	safe.
3025		3198
3026	This functionality is very similar to C<ev_signal> watchers, as signals,	3199	This functionality is very similar to C<ev_signal> watchers, as signals,
3027	too, are asynchronous in nature, and signals, too, will be compressed	3200	too, are asynchronous in nature, and signals, too, will be compressed
3028	(i.e. the number of callback invocations may be less than the number of	3201	(i.e. the number of callback invocations may be less than the number of
3029	C<ev_async_sent> calls).	3202	C<ev_async_sent> calls). In fact, you could use signal watchers as a kind
		3203	of "global async watchers" by using a watcher on an otherwise unused
		3204	signal, and C<ev_feed_signal> to signal this watcher from another thread,
		3205	even without knowing which loop owns the signal.
3030		3206
3031	Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not	3207	Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not
3032	just the default loop.	3208	just the default loop.
3033		3209
3034	=head3 Queueing	3210	=head3 Queueing
…		…
3210	Feed an event on the given fd, as if a file descriptor backend detected	3386	Feed an event on the given fd, as if a file descriptor backend detected
3211	the given events it.	3387	the given events it.
3212		3388
3213	=item ev_feed_signal_event (loop, int signum)	3389	=item ev_feed_signal_event (loop, int signum)
3214		3390
3215	Feed an event as if the given signal occurred (C<loop> must be the default	3391	Feed an event as if the given signal occurred. See also C<ev_feed_signal>,
3216	loop!).	3392	which is async-safe.
3217		3393
3218	=back	3394	=back
		3395
		3396
		3397	=head1 COMMON OR USEFUL IDIOMS (OR BOTH)
		3398
		3399	This section explains some common idioms that are not immediately
		3400	obvious. Note that examples are sprinkled over the whole manual, and this
		3401	section only contains stuff that wouldn't fit anywhere else.
		3402
		3403	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
		3404
		3405	Each watcher has, by default, a C<void *data> member that you can read
		3406	or modify at any time: libev will completely ignore it. This can be used
		3407	to associate arbitrary data with your watcher. If you need more data and
		3408	don't want to allocate memory separately and store a pointer to it in that
		3409	data member, you can also "subclass" the watcher type and provide your own
		3410	data:
		3411
		3412	struct my_io
		3413	{
		3414	ev_io io;
		3415	int otherfd;
		3416	void *somedata;
		3417	struct whatever *mostinteresting;
		3418	};
		3419
		3420	...
		3421	struct my_io w;
		3422	ev_io_init (&w.io, my_cb, fd, EV_READ);
		3423
		3424	And since your callback will be called with a pointer to the watcher, you
		3425	can cast it back to your own type:
		3426
		3427	static void my_cb (struct ev_loop *loop, ev_io *w_, int revents)
		3428	{
		3429	struct my_io *w = (struct my_io *)w_;
		3430	...
		3431	}
		3432
		3433	More interesting and less C-conformant ways of casting your callback
		3434	function type instead have been omitted.
		3435
		3436	=head2 BUILDING YOUR OWN COMPOSITE WATCHERS
		3437
		3438	Another common scenario is to use some data structure with multiple
		3439	embedded watchers, in effect creating your own watcher that combines
		3440	multiple libev event sources into one "super-watcher":
		3441
		3442	struct my_biggy
		3443	{
		3444	int some_data;
		3445	ev_timer t1;
		3446	ev_timer t2;
		3447	}
		3448
		3449	In this case getting the pointer to C<my_biggy> is a bit more
		3450	complicated: Either you store the address of your C<my_biggy> struct in
		3451	the C<data> member of the watcher (for woozies or C++ coders), or you need
		3452	to use some pointer arithmetic using C<offsetof> inside your watchers (for
		3453	real programmers):
		3454
		3455	#include <stddef.h>
		3456
		3457	static void
		3458	t1_cb (EV_P_ ev_timer *w, int revents)
		3459	{
		3460	struct my_biggy big = (struct my_biggy *)
		3461	(((char *)w) - offsetof (struct my_biggy, t1));
		3462	}
		3463
		3464	static void
		3465	t2_cb (EV_P_ ev_timer *w, int revents)
		3466	{
		3467	struct my_biggy big = (struct my_biggy *)
		3468	(((char *)w) - offsetof (struct my_biggy, t2));
		3469	}
		3470
		3471	=head2 MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS
		3472
		3473	Often (especially in GUI toolkits) there are places where you have
		3474	I<modal> interaction, which is most easily implemented by recursively
		3475	invoking C<ev_run>.
		3476
		3477	This brings the problem of exiting - a callback might want to finish the
		3478	main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but
		3479	a modal "Are you sure?" dialog is still waiting), or just the nested one
		3480	and not the main one (e.g. user clocked "Ok" in a modal dialog), or some
		3481	other combination: In these cases, C<ev_break> will not work alone.
		3482
		3483	The solution is to maintain "break this loop" variable for each C<ev_run>
		3484	invocation, and use a loop around C<ev_run> until the condition is
		3485	triggered, using C<EVRUN_ONCE>:
		3486
		3487	// main loop
		3488	int exit_main_loop = 0;
		3489
		3490	while (!exit_main_loop)
		3491	ev_run (EV_DEFAULT_ EVRUN_ONCE);
		3492
		3493	// in a model watcher
		3494	int exit_nested_loop = 0;
		3495
		3496	while (!exit_nested_loop)
		3497	ev_run (EV_A_ EVRUN_ONCE);
		3498
		3499	To exit from any of these loops, just set the corresponding exit variable:
		3500
		3501	// exit modal loop
		3502	exit_nested_loop = 1;
		3503
		3504	// exit main program, after modal loop is finished
		3505	exit_main_loop = 1;
		3506
		3507	// exit both
		3508	exit_main_loop = exit_nested_loop = 1;
		3509
		3510	=head2 THREAD LOCKING EXAMPLE
		3511
		3512	Here is a fictitious example of how to run an event loop in a different
		3513	thread from where callbacks are being invoked and watchers are
		3514	created/added/removed.
		3515
		3516	For a real-world example, see the C<EV::Loop::Async> perl module,
		3517	which uses exactly this technique (which is suited for many high-level
		3518	languages).
		3519
		3520	The example uses a pthread mutex to protect the loop data, a condition
		3521	variable to wait for callback invocations, an async watcher to notify the
		3522	event loop thread and an unspecified mechanism to wake up the main thread.
		3523
		3524	First, you need to associate some data with the event loop:
		3525
		3526	typedef struct {
		3527	mutex_t lock; /* global loop lock */
		3528	ev_async async_w;
		3529	thread_t tid;
		3530	cond_t invoke_cv;
		3531	} userdata;
		3532
		3533	void prepare_loop (EV_P)
		3534	{
		3535	// for simplicity, we use a static userdata struct.
		3536	static userdata u;
		3537
		3538	ev_async_init (&u->async_w, async_cb);
		3539	ev_async_start (EV_A_ &u->async_w);
		3540
		3541	pthread_mutex_init (&u->lock, 0);
		3542	pthread_cond_init (&u->invoke_cv, 0);
		3543
		3544	// now associate this with the loop
		3545	ev_set_userdata (EV_A_ u);
		3546	ev_set_invoke_pending_cb (EV_A_ l_invoke);
		3547	ev_set_loop_release_cb (EV_A_ l_release, l_acquire);
		3548
		3549	// then create the thread running ev_loop
		3550	pthread_create (&u->tid, 0, l_run, EV_A);
		3551	}
		3552
		3553	The callback for the C<ev_async> watcher does nothing: the watcher is used
		3554	solely to wake up the event loop so it takes notice of any new watchers
		3555	that might have been added:
		3556
		3557	static void
		3558	async_cb (EV_P_ ev_async *w, int revents)
		3559	{
		3560	// just used for the side effects
		3561	}
		3562
		3563	The C<l_release> and C<l_acquire> callbacks simply unlock/lock the mutex
		3564	protecting the loop data, respectively.
		3565
		3566	static void
		3567	l_release (EV_P)
		3568	{
		3569	userdata *u = ev_userdata (EV_A);
		3570	pthread_mutex_unlock (&u->lock);
		3571	}
		3572
		3573	static void
		3574	l_acquire (EV_P)
		3575	{
		3576	userdata *u = ev_userdata (EV_A);
		3577	pthread_mutex_lock (&u->lock);
		3578	}
		3579
		3580	The event loop thread first acquires the mutex, and then jumps straight
		3581	into C<ev_run>:
		3582
		3583	void *
		3584	l_run (void *thr_arg)
		3585	{
		3586	struct ev_loop *loop = (struct ev_loop *)thr_arg;
		3587
		3588	l_acquire (EV_A);
		3589	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
		3590	ev_run (EV_A_ 0);
		3591	l_release (EV_A);
		3592
		3593	return 0;
		3594	}
		3595
		3596	Instead of invoking all pending watchers, the C<l_invoke> callback will
		3597	signal the main thread via some unspecified mechanism (signals? pipe
		3598	writes? C<Async::Interrupt>?) and then waits until all pending watchers
		3599	have been called (in a while loop because a) spurious wakeups are possible
		3600	and b) skipping inter-thread-communication when there are no pending
		3601	watchers is very beneficial):
		3602
		3603	static void
		3604	l_invoke (EV_P)
		3605	{
		3606	userdata *u = ev_userdata (EV_A);
		3607
		3608	while (ev_pending_count (EV_A))
		3609	{
		3610	wake_up_other_thread_in_some_magic_or_not_so_magic_way ();
		3611	pthread_cond_wait (&u->invoke_cv, &u->lock);
		3612	}
		3613	}
		3614
		3615	Now, whenever the main thread gets told to invoke pending watchers, it
		3616	will grab the lock, call C<ev_invoke_pending> and then signal the loop
		3617	thread to continue:
		3618
		3619	static void
		3620	real_invoke_pending (EV_P)
		3621	{
		3622	userdata *u = ev_userdata (EV_A);
		3623
		3624	pthread_mutex_lock (&u->lock);
		3625	ev_invoke_pending (EV_A);
		3626	pthread_cond_signal (&u->invoke_cv);
		3627	pthread_mutex_unlock (&u->lock);
		3628	}
		3629
		3630	Whenever you want to start/stop a watcher or do other modifications to an
		3631	event loop, you will now have to lock:
		3632
		3633	ev_timer timeout_watcher;
		3634	userdata *u = ev_userdata (EV_A);
		3635
		3636	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
		3637
		3638	pthread_mutex_lock (&u->lock);
		3639	ev_timer_start (EV_A_ &timeout_watcher);
		3640	ev_async_send (EV_A_ &u->async_w);
		3641	pthread_mutex_unlock (&u->lock);
		3642
		3643	Note that sending the C<ev_async> watcher is required because otherwise
		3644	an event loop currently blocking in the kernel will have no knowledge
		3645	about the newly added timer. By waking up the loop it will pick up any new
		3646	watchers in the next event loop iteration.
		3647
		3648	=head2 THREADS, COROUTINES, CONTINUATIONS, QUEUES... INSTEAD OF CALLBACKS
		3649
		3650	While the overhead of a callback that e.g. schedules a thread is small, it
		3651	is still an overhead. If you embed libev, and your main usage is with some
		3652	kind of threads or coroutines, you might want to customise libev so that
		3653	doesn't need callbacks anymore.
		3654
		3655	Imagine you have coroutines that you can switch to using a function
		3656	C<switch_to (coro)>, that libev runs in a coroutine called C<libev_coro>
		3657	and that due to some magic, the currently active coroutine is stored in a
		3658	global called C<current_coro>. Then you can build your own "wait for libev
		3659	event" primitive by changing C<EV_CB_DECLARE> and C<EV_CB_INVOKE> (note
		3660	the differing C<;> conventions):
		3661
		3662	#define EV_CB_DECLARE(type) struct my_coro *cb;
		3663	#define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb)
		3664
		3665	That means instead of having a C callback function, you store the
		3666	coroutine to switch to in each watcher, and instead of having libev call
		3667	your callback, you instead have it switch to that coroutine.
		3668
		3669	A coroutine might now wait for an event with a function called
		3670	C<wait_for_event>. (the watcher needs to be started, as always, but it doesn't
		3671	matter when, or whether the watcher is active or not when this function is
		3672	called):
		3673
		3674	void
		3675	wait_for_event (ev_watcher *w)
		3676	{
		3677	ev_cb_set (w) = current_coro;
		3678	switch_to (libev_coro);
		3679	}
		3680
		3681	That basically suspends the coroutine inside C<wait_for_event> and
		3682	continues the libev coroutine, which, when appropriate, switches back to
		3683	this or any other coroutine. I am sure if you sue this your own :)
		3684
		3685	You can do similar tricks if you have, say, threads with an event queue -
		3686	instead of storing a coroutine, you store the queue object and instead of
		3687	switching to a coroutine, you push the watcher onto the queue and notify
		3688	any waiters.
		3689
		3690	To embed libev, see L<EMBEDDING>, but in short, it's easiest to create two
		3691	files, F<my_ev.h> and F<my_ev.c> that include the respective libev files:
		3692
		3693	// my_ev.h
		3694	#define EV_CB_DECLARE(type) struct my_coro *cb;
		3695	#define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb);
		3696	#include "../libev/ev.h"
		3697
		3698	// my_ev.c
		3699	#define EV_H "my_ev.h"
		3700	#include "../libev/ev.c"
		3701
		3702	And then use F<my_ev.h> when you would normally use F<ev.h>, and compile
		3703	F<my_ev.c> into your project. When properly specifying include paths, you
		3704	can even use F<ev.h> as header file name directly.
3219		3705
3220		3706
3221	=head1 LIBEVENT EMULATION	3707	=head1 LIBEVENT EMULATION
3222		3708
3223	Libev offers a compatibility emulation layer for libevent. It cannot	3709	Libev offers a compatibility emulation layer for libevent. It cannot
3224	emulate the internals of libevent, so here are some usage hints:	3710	emulate the internals of libevent, so here are some usage hints:
3225		3711
3226	=over 4	3712	=over 4
		3713
		3714	=item * Only the libevent-1.4.1-beta API is being emulated.
		3715
		3716	This was the newest libevent version available when libev was implemented,
		3717	and is still mostly unchanged in 2010.
3227		3718
3228	=item * Use it by including <event.h>, as usual.	3719	=item * Use it by including <event.h>, as usual.
3229		3720
3230	=item * The following members are fully supported: ev_base, ev_callback,	3721	=item * The following members are fully supported: ev_base, ev_callback,
3231	ev_arg, ev_fd, ev_res, ev_events.	3722	ev_arg, ev_fd, ev_res, ev_events.
…		…
3237	=item * Priorities are not currently supported. Initialising priorities	3728	=item * Priorities are not currently supported. Initialising priorities
3238	will fail and all watchers will have the same priority, even though there	3729	will fail and all watchers will have the same priority, even though there
3239	is an ev_pri field.	3730	is an ev_pri field.
3240		3731
3241	=item * In libevent, the last base created gets the signals, in libev, the	3732	=item * In libevent, the last base created gets the signals, in libev, the
3242	first base created (== the default loop) gets the signals.	3733	base that registered the signal gets the signals.
3243		3734
3244	=item * Other members are not supported.	3735	=item * Other members are not supported.
3245		3736
3246	=item * The libev emulation is I<not> ABI compatible to libevent, you need	3737	=item * The libev emulation is I<not> ABI compatible to libevent, you need
3247	to use the libev header file and library.	3738	to use the libev header file and library.
…		…
3266	Care has been taken to keep the overhead low. The only data member the C++	3757	Care has been taken to keep the overhead low. The only data member the C++
3267	classes add (compared to plain C-style watchers) is the event loop pointer	3758	classes add (compared to plain C-style watchers) is the event loop pointer
3268	that the watcher is associated with (or no additional members at all if	3759	that the watcher is associated with (or no additional members at all if
3269	you disable C<EV_MULTIPLICITY> when embedding libev).	3760	you disable C<EV_MULTIPLICITY> when embedding libev).
3270		3761
3271	Currently, functions, and static and non-static member functions can be	3762	Currently, functions, static and non-static member functions and classes
3272	used as callbacks. Other types should be easy to add as long as they only	3763	with C<operator ()> can be used as callbacks. Other types should be easy
3273	need one additional pointer for context. If you need support for other	3764	to add as long as they only need one additional pointer for context. If
3274	types of functors please contact the author (preferably after implementing	3765	you need support for other types of functors please contact the author
3275	it).	3766	(preferably after implementing it).
3276		3767
3277	Here is a list of things available in the C<ev> namespace:	3768	Here is a list of things available in the C<ev> namespace:
3278		3769
3279	=over 4	3770	=over 4
3280		3771
…		…
3390	Associates a different C<struct ev_loop> with this watcher. You can only	3881	Associates a different C<struct ev_loop> with this watcher. You can only
3391	do this when the watcher is inactive (and not pending either).	3882	do this when the watcher is inactive (and not pending either).
3392		3883
3393	=item w->set ([arguments])	3884	=item w->set ([arguments])
3394		3885
3395	Basically the same as C<ev_TYPE_set>, with the same arguments. Must be	3886	Basically the same as C<ev_TYPE_set>, with the same arguments. Either this
3396	called at least once. Unlike the C counterpart, an active watcher gets	3887	method or a suitable start method must be called at least once. Unlike the
3397	automatically stopped and restarted when reconfiguring it with this	3888	C counterpart, an active watcher gets automatically stopped and restarted
3398	method.	3889	when reconfiguring it with this method.
3399		3890
3400	=item w->start ()	3891	=item w->start ()
3401		3892
3402	Starts the watcher. Note that there is no C<loop> argument, as the	3893	Starts the watcher. Note that there is no C<loop> argument, as the
3403	constructor already stores the event loop.	3894	constructor already stores the event loop.
3404		3895
		3896	=item w->start ([arguments])
		3897
		3898	Instead of calling C<set> and C<start> methods separately, it is often
		3899	convenient to wrap them in one call. Uses the same type of arguments as
		3900	the configure C<set> method of the watcher.
		3901
3405	=item w->stop ()	3902	=item w->stop ()
3406		3903
3407	Stops the watcher if it is active. Again, no C<loop> argument.	3904	Stops the watcher if it is active. Again, no C<loop> argument.
3408		3905
3409	=item w->again () (C<ev::timer>, C<ev::periodic> only)	3906	=item w->again () (C<ev::timer>, C<ev::periodic> only)
…		…
3421		3918
3422	=back	3919	=back
3423		3920
3424	=back	3921	=back
3425		3922
3426	Example: Define a class with an IO and idle watcher, start one of them in	3923	Example: Define a class with two I/O and idle watchers, start the I/O
3427	the constructor.	3924	watchers in the constructor.
3428		3925
3429	class myclass	3926	class myclass
3430	{	3927	{
3431	ev::io io ; void io_cb (ev::io &w, int revents);	3928	ev::io io ; void io_cb (ev::io &w, int revents);
		3929	ev::io2 io2 ; void io2_cb (ev::io &w, int revents);
3432	ev::idle idle; void idle_cb (ev::idle &w, int revents);	3930	ev::idle idle; void idle_cb (ev::idle &w, int revents);
3433		3931
3434	myclass (int fd)	3932	myclass (int fd)
3435	{	3933	{
3436	io .set <myclass, &myclass::io_cb > (this);	3934	io .set <myclass, &myclass::io_cb > (this);
		3935	io2 .set <myclass, &myclass::io2_cb > (this);
3437	idle.set <myclass, &myclass::idle_cb> (this);	3936	idle.set <myclass, &myclass::idle_cb> (this);
3438		3937
3439	io.start (fd, ev::READ);	3938	io.set (fd, ev::WRITE); // configure the watcher
		3939	io.start (); // start it whenever convenient
		3940
		3941	io2.start (fd, ev::READ); // set + start in one call
3440	}	3942	}
3441	};	3943	};
3442		3944
3443		3945
3444	=head1 OTHER LANGUAGE BINDINGS	3946	=head1 OTHER LANGUAGE BINDINGS
…		…
3518	loop argument"). The C<EV_A> form is used when this is the sole argument,	4020	loop argument"). The C<EV_A> form is used when this is the sole argument,
3519	C<EV_A_> is used when other arguments are following. Example:	4021	C<EV_A_> is used when other arguments are following. Example:
3520		4022
3521	ev_unref (EV_A);	4023	ev_unref (EV_A);
3522	ev_timer_add (EV_A_ watcher);	4024	ev_timer_add (EV_A_ watcher);
3523	ev_loop (EV_A_ 0);	4025	ev_run (EV_A_ 0);
3524		4026
3525	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	4027	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
3526	which is often provided by the following macro.	4028	which is often provided by the following macro.
3527		4029
3528	=item C<EV_P>, C<EV_P_>	4030	=item C<EV_P>, C<EV_P_>
…		…
3568	}	4070	}
3569		4071
3570	ev_check check;	4072	ev_check check;
3571	ev_check_init (&check, check_cb);	4073	ev_check_init (&check, check_cb);
3572	ev_check_start (EV_DEFAULT_ &check);	4074	ev_check_start (EV_DEFAULT_ &check);
3573	ev_loop (EV_DEFAULT_ 0);	4075	ev_run (EV_DEFAULT_ 0);
3574		4076
3575	=head1 EMBEDDING	4077	=head1 EMBEDDING
3576		4078
3577	Libev can (and often is) directly embedded into host	4079	Libev can (and often is) directly embedded into host
3578	applications. Examples of applications that embed it include the Deliantra	4080	applications. Examples of applications that embed it include the Deliantra
…		…
3669	to a compiled library. All other symbols change the ABI, which means all	4171	to a compiled library. All other symbols change the ABI, which means all
3670	users of libev and the libev code itself must be compiled with compatible	4172	users of libev and the libev code itself must be compiled with compatible
3671	settings.	4173	settings.
3672		4174
3673	=over 4	4175	=over 4
		4176
		4177	=item EV_COMPAT3 (h)
		4178
		4179	Backwards compatibility is a major concern for libev. This is why this
		4180	release of libev comes with wrappers for the functions and symbols that
		4181	have been renamed between libev version 3 and 4.
		4182
		4183	You can disable these wrappers (to test compatibility with future
		4184	versions) by defining C<EV_COMPAT3> to C<0> when compiling your
		4185	sources. This has the additional advantage that you can drop the C<struct>
		4186	from C<struct ev_loop> declarations, as libev will provide an C<ev_loop>
		4187	typedef in that case.
		4188
		4189	In some future version, the default for C<EV_COMPAT3> will become C<0>,
		4190	and in some even more future version the compatibility code will be
		4191	removed completely.
3674		4192
3675	=item EV_STANDALONE (h)	4193	=item EV_STANDALONE (h)
3676		4194
3677	Must always be C<1> if you do not use autoconf configuration, which	4195	Must always be C<1> if you do not use autoconf configuration, which
3678	keeps libev from including F<config.h>, and it also defines dummy	4196	keeps libev from including F<config.h>, and it also defines dummy
…		…
4028	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it	4546	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
4029	will be C<0>.	4547	will be C<0>.
4030		4548
4031	=item EV_VERIFY	4549	=item EV_VERIFY
4032		4550
4033	Controls how much internal verification (see C<ev_loop_verify ()>) will	4551	Controls how much internal verification (see C<ev_verify ()>) will
4034	be done: If set to C<0>, no internal verification code will be compiled	4552	be done: If set to C<0>, no internal verification code will be compiled
4035	in. If set to C<1>, then verification code will be compiled in, but not	4553	in. If set to C<1>, then verification code will be compiled in, but not
4036	called. If set to C<2>, then the internal verification code will be	4554	called. If set to C<2>, then the internal verification code will be
4037	called once per loop, which can slow down libev. If set to C<3>, then the	4555	called once per loop, which can slow down libev. If set to C<3>, then the
4038	verification code will be called very frequently, which will slow down	4556	verification code will be called very frequently, which will slow down
…		…
4121	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	4639	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
4122		4640
4123	#include "ev_cpp.h"	4641	#include "ev_cpp.h"
4124	#include "ev.c"	4642	#include "ev.c"
4125		4643
4126	=head1 INTERACTION WITH OTHER PROGRAMS OR LIBRARIES	4644	=head1 INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT
4127		4645
4128	=head2 THREADS AND COROUTINES	4646	=head2 THREADS AND COROUTINES
4129		4647
4130	=head3 THREADS	4648	=head3 THREADS
4131		4649
…		…
4182	default loop and triggering an C<ev_async> watcher from the default loop	4700	default loop and triggering an C<ev_async> watcher from the default loop
4183	watcher callback into the event loop interested in the signal.	4701	watcher callback into the event loop interested in the signal.
4184		4702
4185	=back	4703	=back
4186		4704
4187	=head4 THREAD LOCKING EXAMPLE	4705	See also L<THREAD LOCKING EXAMPLE>.
4188
4189	Here is a fictitious example of how to run an event loop in a different
4190	thread than where callbacks are being invoked and watchers are
4191	created/added/removed.
4192
4193	For a real-world example, see the C<EV::Loop::Async> perl module,
4194	which uses exactly this technique (which is suited for many high-level
4195	languages).
4196
4197	The example uses a pthread mutex to protect the loop data, a condition
4198	variable to wait for callback invocations, an async watcher to notify the
4199	event loop thread and an unspecified mechanism to wake up the main thread.
4200
4201	First, you need to associate some data with the event loop:
4202
4203	typedef struct {
4204	mutex_t lock; /* global loop lock */
4205	ev_async async_w;
4206	thread_t tid;
4207	cond_t invoke_cv;
4208	} userdata;
4209
4210	void prepare_loop (EV_P)
4211	{
4212	// for simplicity, we use a static userdata struct.
4213	static userdata u;
4214
4215	ev_async_init (&u->async_w, async_cb);
4216	ev_async_start (EV_A_ &u->async_w);
4217
4218	pthread_mutex_init (&u->lock, 0);
4219	pthread_cond_init (&u->invoke_cv, 0);
4220
4221	// now associate this with the loop
4222	ev_set_userdata (EV_A_ u);
4223	ev_set_invoke_pending_cb (EV_A_ l_invoke);
4224	ev_set_loop_release_cb (EV_A_ l_release, l_acquire);
4225
4226	// then create the thread running ev_loop
4227	pthread_create (&u->tid, 0, l_run, EV_A);
4228	}
4229
4230	The callback for the C<ev_async> watcher does nothing: the watcher is used
4231	solely to wake up the event loop so it takes notice of any new watchers
4232	that might have been added:
4233
4234	static void
4235	async_cb (EV_P_ ev_async *w, int revents)
4236	{
4237	// just used for the side effects
4238	}
4239
4240	The C<l_release> and C<l_acquire> callbacks simply unlock/lock the mutex
4241	protecting the loop data, respectively.
4242
4243	static void
4244	l_release (EV_P)
4245	{
4246	userdata *u = ev_userdata (EV_A);
4247	pthread_mutex_unlock (&u->lock);
4248	}
4249
4250	static void
4251	l_acquire (EV_P)
4252	{
4253	userdata *u = ev_userdata (EV_A);
4254	pthread_mutex_lock (&u->lock);
4255	}
4256
4257	The event loop thread first acquires the mutex, and then jumps straight
4258	into C<ev_loop>:
4259
4260	void *
4261	l_run (void *thr_arg)
4262	{
4263	struct ev_loop *loop = (struct ev_loop *)thr_arg;
4264
4265	l_acquire (EV_A);
4266	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
4267	ev_loop (EV_A_ 0);
4268	l_release (EV_A);
4269
4270	return 0;
4271	}
4272
4273	Instead of invoking all pending watchers, the C<l_invoke> callback will
4274	signal the main thread via some unspecified mechanism (signals? pipe
4275	writes? C<Async::Interrupt>?) and then waits until all pending watchers
4276	have been called (in a while loop because a) spurious wakeups are possible
4277	and b) skipping inter-thread-communication when there are no pending
4278	watchers is very beneficial):
4279
4280	static void
4281	l_invoke (EV_P)
4282	{
4283	userdata *u = ev_userdata (EV_A);
4284
4285	while (ev_pending_count (EV_A))
4286	{
4287	wake_up_other_thread_in_some_magic_or_not_so_magic_way ();
4288	pthread_cond_wait (&u->invoke_cv, &u->lock);
4289	}
4290	}
4291
4292	Now, whenever the main thread gets told to invoke pending watchers, it
4293	will grab the lock, call C<ev_invoke_pending> and then signal the loop
4294	thread to continue:
4295
4296	static void
4297	real_invoke_pending (EV_P)
4298	{
4299	userdata *u = ev_userdata (EV_A);
4300
4301	pthread_mutex_lock (&u->lock);
4302	ev_invoke_pending (EV_A);
4303	pthread_cond_signal (&u->invoke_cv);
4304	pthread_mutex_unlock (&u->lock);
4305	}
4306
4307	Whenever you want to start/stop a watcher or do other modifications to an
4308	event loop, you will now have to lock:
4309
4310	ev_timer timeout_watcher;
4311	userdata *u = ev_userdata (EV_A);
4312
4313	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
4314
4315	pthread_mutex_lock (&u->lock);
4316	ev_timer_start (EV_A_ &timeout_watcher);
4317	ev_async_send (EV_A_ &u->async_w);
4318	pthread_mutex_unlock (&u->lock);
4319
4320	Note that sending the C<ev_async> watcher is required because otherwise
4321	an event loop currently blocking in the kernel will have no knowledge
4322	about the newly added timer. By waking up the loop it will pick up any new
4323	watchers in the next event loop iteration.
4324		4706
4325	=head3 COROUTINES	4707	=head3 COROUTINES
4326		4708
4327	Libev is very accommodating to coroutines ("cooperative threads"):	4709	Libev is very accommodating to coroutines ("cooperative threads"):
4328	libev fully supports nesting calls to its functions from different	4710	libev fully supports nesting calls to its functions from different
4329	coroutines (e.g. you can call C<ev_loop> on the same loop from two	4711	coroutines (e.g. you can call C<ev_run> on the same loop from two
4330	different coroutines, and switch freely between both coroutines running	4712	different coroutines, and switch freely between both coroutines running
4331	the loop, as long as you don't confuse yourself). The only exception is	4713	the loop, as long as you don't confuse yourself). The only exception is
4332	that you must not do this from C<ev_periodic> reschedule callbacks.	4714	that you must not do this from C<ev_periodic> reschedule callbacks.
4333		4715
4334	Care has been taken to ensure that libev does not keep local state inside	4716	Care has been taken to ensure that libev does not keep local state inside
4335	C<ev_loop>, and other calls do not usually allow for coroutine switches as	4717	C<ev_run>, and other calls do not usually allow for coroutine switches as
4336	they do not call any callbacks.	4718	they do not call any callbacks.
4337		4719
4338	=head2 COMPILER WARNINGS	4720	=head2 COMPILER WARNINGS
4339		4721
4340	Depending on your compiler and compiler settings, you might get no or a	4722	Depending on your compiler and compiler settings, you might get no or a
…		…
4397	I suggest using suppression lists.	4779	I suggest using suppression lists.
4398		4780
4399		4781
4400	=head1 PORTABILITY NOTES	4782	=head1 PORTABILITY NOTES
4401		4783
		4784	=head2 GNU/LINUX 32 BIT LIMITATIONS
		4785
		4786	GNU/Linux is the only common platform that supports 64 bit file/large file
		4787	interfaces but I<disables> them by default.
		4788
		4789	That means that libev compiled in the default environment doesn't support
		4790	files larger than 2GiB or so, which mainly affects C<ev_stat> watchers.
		4791
		4792	Unfortunately, many programs try to work around this GNU/Linux issue
		4793	by enabling the large file API, which makes them incompatible with the
		4794	standard libev compiled for their system.
		4795
		4796	Likewise, libev cannot enable the large file API itself as this would
		4797	suddenly make it incompatible to the default compile time environment,
		4798	i.e. all programs not using special compile switches.
		4799
		4800	=head2 OS/X AND DARWIN BUGS
		4801
		4802	The whole thing is a bug if you ask me - basically any system interface
		4803	you touch is broken, whether it is locales, poll, kqueue or even the
		4804	OpenGL drivers.
		4805
		4806	=head3 C<kqueue> is buggy
		4807
		4808	The kqueue syscall is broken in all known versions - most versions support
		4809	only sockets, many support pipes.
		4810
		4811	Libev tries to work around this by not using C<kqueue> by default on this
		4812	rotten platform, but of course you can still ask for it when creating a
		4813	loop - embedding a socket-only kqueue loop into a select-based one is
		4814	probably going to work well.
		4815
		4816	=head3 C<poll> is buggy
		4817
		4818	Instead of fixing C<kqueue>, Apple replaced their (working) C<poll>
		4819	implementation by something calling C<kqueue> internally around the 10.5.6
		4820	release, so now C<kqueue> I<and> C<poll> are broken.
		4821
		4822	Libev tries to work around this by not using C<poll> by default on
		4823	this rotten platform, but of course you can still ask for it when creating
		4824	a loop.
		4825
		4826	=head3 C<select> is buggy
		4827
		4828	All that's left is C<select>, and of course Apple found a way to fuck this
		4829	one up as well: On OS/X, C<select> actively limits the number of file
		4830	descriptors you can pass in to 1024 - your program suddenly crashes when
		4831	you use more.
		4832
		4833	There is an undocumented "workaround" for this - defining
		4834	C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should>
		4835	work on OS/X.
		4836
		4837	=head2 SOLARIS PROBLEMS AND WORKAROUNDS
		4838
		4839	=head3 C<errno> reentrancy
		4840
		4841	The default compile environment on Solaris is unfortunately so
		4842	thread-unsafe that you can't even use components/libraries compiled
		4843	without C<-D_REENTRANT> in a threaded program, which, of course, isn't
		4844	defined by default. A valid, if stupid, implementation choice.
		4845
		4846	If you want to use libev in threaded environments you have to make sure
		4847	it's compiled with C<_REENTRANT> defined.
		4848
		4849	=head3 Event port backend
		4850
		4851	The scalable event interface for Solaris is called "event
		4852	ports". Unfortunately, this mechanism is very buggy in all major
		4853	releases. If you run into high CPU usage, your program freezes or you get
		4854	a large number of spurious wakeups, make sure you have all the relevant
		4855	and latest kernel patches applied. No, I don't know which ones, but there
		4856	are multiple ones to apply, and afterwards, event ports actually work
		4857	great.
		4858
		4859	If you can't get it to work, you can try running the program by setting
		4860	the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and
		4861	C<select> backends.
		4862
		4863	=head2 AIX POLL BUG
		4864
		4865	AIX unfortunately has a broken C<poll.h> header. Libev works around
		4866	this by trying to avoid the poll backend altogether (i.e. it's not even
		4867	compiled in), which normally isn't a big problem as C<select> works fine
		4868	with large bitsets on AIX, and AIX is dead anyway.
		4869
4402	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS	4870	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
		4871
		4872	=head3 General issues
4403		4873
4404	Win32 doesn't support any of the standards (e.g. POSIX) that libev	4874	Win32 doesn't support any of the standards (e.g. POSIX) that libev
4405	requires, and its I/O model is fundamentally incompatible with the POSIX	4875	requires, and its I/O model is fundamentally incompatible with the POSIX
4406	model. Libev still offers limited functionality on this platform in	4876	model. Libev still offers limited functionality on this platform in
4407	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	4877	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
4408	descriptors. This only applies when using Win32 natively, not when using	4878	descriptors. This only applies when using Win32 natively, not when using
4409	e.g. cygwin.	4879	e.g. cygwin. Actually, it only applies to the microsofts own compilers,
		4880	as every compielr comes with a slightly differently broken/incompatible
		4881	environment.
4410		4882
4411	Lifting these limitations would basically require the full	4883	Lifting these limitations would basically require the full
4412	re-implementation of the I/O system. If you are into these kinds of	4884	re-implementation of the I/O system. If you are into this kind of thing,
4413	things, then note that glib does exactly that for you in a very portable	4885	then note that glib does exactly that for you in a very portable way (note
4414	way (note also that glib is the slowest event library known to man).	4886	also that glib is the slowest event library known to man).
4415		4887
4416	There is no supported compilation method available on windows except	4888	There is no supported compilation method available on windows except
4417	embedding it into other applications.	4889	embedding it into other applications.
4418		4890
4419	Sensible signal handling is officially unsupported by Microsoft - libev	4891	Sensible signal handling is officially unsupported by Microsoft - libev
…		…
4447	you do I<not> compile the F<ev.c> or any other embedded source files!):	4919	you do I<not> compile the F<ev.c> or any other embedded source files!):
4448		4920
4449	#include "evwrap.h"	4921	#include "evwrap.h"
4450	#include "ev.c"	4922	#include "ev.c"
4451		4923
4452	=over 4
4453
4454	=item The winsocket select function	4924	=head3 The winsocket C<select> function
4455		4925
4456	The winsocket C<select> function doesn't follow POSIX in that it	4926	The winsocket C<select> function doesn't follow POSIX in that it
4457	requires socket I<handles> and not socket I<file descriptors> (it is	4927	requires socket I<handles> and not socket I<file descriptors> (it is
4458	also extremely buggy). This makes select very inefficient, and also	4928	also extremely buggy). This makes select very inefficient, and also
4459	requires a mapping from file descriptors to socket handles (the Microsoft	4929	requires a mapping from file descriptors to socket handles (the Microsoft
…		…
4468	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */	4938	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
4469		4939
4470	Note that winsockets handling of fd sets is O(n), so you can easily get a	4940	Note that winsockets handling of fd sets is O(n), so you can easily get a
4471	complexity in the O(n²) range when using win32.	4941	complexity in the O(n²) range when using win32.
4472		4942
4473	=item Limited number of file descriptors	4943	=head3 Limited number of file descriptors
4474		4944
4475	Windows has numerous arbitrary (and low) limits on things.	4945	Windows has numerous arbitrary (and low) limits on things.
4476		4946
4477	Early versions of winsocket's select only supported waiting for a maximum	4947	Early versions of winsocket's select only supported waiting for a maximum
4478	of C<64> handles (probably owning to the fact that all windows kernels	4948	of C<64> handles (probably owning to the fact that all windows kernels
…		…
4493	runtime libraries. This might get you to about C<512> or C<2048> sockets	4963	runtime libraries. This might get you to about C<512> or C<2048> sockets
4494	(depending on windows version and/or the phase of the moon). To get more,	4964	(depending on windows version and/or the phase of the moon). To get more,
4495	you need to wrap all I/O functions and provide your own fd management, but	4965	you need to wrap all I/O functions and provide your own fd management, but
4496	the cost of calling select (O(n²)) will likely make this unworkable.	4966	the cost of calling select (O(n²)) will likely make this unworkable.
4497		4967
4498	=back
4499
4500	=head2 PORTABILITY REQUIREMENTS	4968	=head2 PORTABILITY REQUIREMENTS
4501		4969
4502	In addition to a working ISO-C implementation and of course the	4970	In addition to a working ISO-C implementation and of course the
4503	backend-specific APIs, libev relies on a few additional extensions:	4971	backend-specific APIs, libev relies on a few additional extensions:
4504		4972
…		…
4510	Libev assumes not only that all watcher pointers have the same internal	4978	Libev assumes not only that all watcher pointers have the same internal
4511	structure (guaranteed by POSIX but not by ISO C for example), but it also	4979	structure (guaranteed by POSIX but not by ISO C for example), but it also
4512	assumes that the same (machine) code can be used to call any watcher	4980	assumes that the same (machine) code can be used to call any watcher
4513	callback: The watcher callbacks have different type signatures, but libev	4981	callback: The watcher callbacks have different type signatures, but libev
4514	calls them using an C<ev_watcher *> internally.	4982	calls them using an C<ev_watcher *> internally.
		4983
		4984	=item pointer accesses must be thread-atomic
		4985
		4986	Accessing a pointer value must be atomic, it must both be readable and
		4987	writable in one piece - this is the case on all current architectures.
4515		4988
4516	=item C<sig_atomic_t volatile> must be thread-atomic as well	4989	=item C<sig_atomic_t volatile> must be thread-atomic as well
4517		4990
4518	The type C<sig_atomic_t volatile> (or whatever is defined as	4991	The type C<sig_atomic_t volatile> (or whatever is defined as
4519	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different	4992	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different
…		…
4542	watchers.	5015	watchers.
4543		5016
4544	=item C<double> must hold a time value in seconds with enough accuracy	5017	=item C<double> must hold a time value in seconds with enough accuracy
4545		5018
4546	The type C<double> is used to represent timestamps. It is required to	5019	The type C<double> is used to represent timestamps. It is required to
4547	have at least 51 bits of mantissa (and 9 bits of exponent), which is good	5020	have at least 51 bits of mantissa (and 9 bits of exponent), which is
4548	enough for at least into the year 4000. This requirement is fulfilled by	5021	good enough for at least into the year 4000 with millisecond accuracy
		5022	(the design goal for libev). This requirement is overfulfilled by
4549	implementations implementing IEEE 754, which is basically all existing	5023	implementations using IEEE 754, which is basically all existing ones. With
4550	ones. With IEEE 754 doubles, you get microsecond accuracy until at least	5024	IEEE 754 doubles, you get microsecond accuracy until at least 2200.
4551	2200.
4552		5025
4553	=back	5026	=back
4554		5027
4555	If you know of other additional requirements drop me a note.	5028	If you know of other additional requirements drop me a note.
4556		5029
…		…
4626	=back	5099	=back
4627		5100
4628		5101
4629	=head1 PORTING FROM LIBEV 3.X TO 4.X	5102	=head1 PORTING FROM LIBEV 3.X TO 4.X
4630		5103
4631	The major version 4 introduced some minor incompatible changes to the API.	5104	The major version 4 introduced some incompatible changes to the API.
4632		5105
4633	At the moment, the C<ev.h> header file tries to implement superficial	5106	At the moment, the C<ev.h> header file provides compatibility definitions
4634	compatibility, so most programs should still compile. Those might be	5107	for all changes, so most programs should still compile. The compatibility
4635	removed in later versions of libev, so better update early than late.	5108	layer might be removed in later versions of libev, so better update to the
		5109	new API early than late.
4636		5110
4637	=over 4	5111	=over 4
4638		5112
4639	=item C<ev_loop_count> renamed to C<ev_iteration>	5113	=item C<EV_COMPAT3> backwards compatibility mechanism
4640		5114
4641	=item C<ev_loop_depth> renamed to C<ev_depth>	5115	The backward compatibility mechanism can be controlled by
		5116	C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING>
		5117	section.
4642		5118
4643	=item C<ev_loop_verify> renamed to C<ev_verify>	5119	=item C<ev_default_destroy> and C<ev_default_fork> have been removed
		5120
		5121	These calls can be replaced easily by their C<ev_loop_xxx> counterparts:
		5122
		5123	ev_loop_destroy (EV_DEFAULT_UC);
		5124	ev_loop_fork (EV_DEFAULT);
		5125
		5126	=item function/symbol renames
		5127
		5128	A number of functions and symbols have been renamed:
		5129
		5130	ev_loop => ev_run
		5131	EVLOOP_NONBLOCK => EVRUN_NOWAIT
		5132	EVLOOP_ONESHOT => EVRUN_ONCE
		5133
		5134	ev_unloop => ev_break
		5135	EVUNLOOP_CANCEL => EVBREAK_CANCEL
		5136	EVUNLOOP_ONE => EVBREAK_ONE
		5137	EVUNLOOP_ALL => EVBREAK_ALL
		5138
		5139	EV_TIMEOUT => EV_TIMER
		5140
		5141	ev_loop_count => ev_iteration
		5142	ev_loop_depth => ev_depth
		5143	ev_loop_verify => ev_verify
4644		5144
4645	Most functions working on C<struct ev_loop> objects don't have an	5145	Most functions working on C<struct ev_loop> objects don't have an
4646	C<ev_loop_> prefix, so it was removed. Note that C<ev_loop_fork> is	5146	C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and
		5147	associated constants have been renamed to not collide with the C<struct
		5148	ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme
		5149	as all other watcher types. Note that C<ev_loop_fork> is still called
4647	still called C<ev_loop_fork> because it would otherwise clash with the	5150	C<ev_loop_fork> because it would otherwise clash with the C<ev_fork>
4648	C<ev_fork> typedef.	5151	typedef.
4649
4650	=item C<EV_TIMEOUT> renamed to C<EV_TIMER> in C<revents>
4651
4652	This is a simple rename - all other watcher types use their name
4653	as revents flag, and now C<ev_timer> does, too.
4654
4655	Both C<EV_TIMER> and C<EV_TIMEOUT> symbols were present in 3.x versions
4656	and continue to be present for the foreseeable future, so this is mostly a
4657	documentation change.
4658		5152
4659	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>	5153	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>
4660		5154
4661	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different	5155	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different
4662	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile	5156	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile
…		…
4669		5163
4670	=over 4	5164	=over 4
4671		5165
4672	=item active	5166	=item active
4673		5167
4674	A watcher is active as long as it has been started (has been attached to	5168	A watcher is active as long as it has been started and not yet stopped.
4675	an event loop) but not yet stopped (disassociated from the event loop).	5169	See L<WATCHER STATES> for details.
4676		5170
4677	=item application	5171	=item application
4678		5172
4679	In this document, an application is whatever is using libev.	5173	In this document, an application is whatever is using libev.
		5174
		5175	=item backend
		5176
		5177	The part of the code dealing with the operating system interfaces.
4680		5178
4681	=item callback	5179	=item callback
4682		5180
4683	The address of a function that is called when some event has been	5181	The address of a function that is called when some event has been
4684	detected. Callbacks are being passed the event loop, the watcher that	5182	detected. Callbacks are being passed the event loop, the watcher that
4685	received the event, and the actual event bitset.	5183	received the event, and the actual event bitset.
4686		5184
4687	=item callback invocation	5185	=item callback/watcher invocation
4688		5186
4689	The act of calling the callback associated with a watcher.	5187	The act of calling the callback associated with a watcher.
4690		5188
4691	=item event	5189	=item event
4692		5190
…		…
4711	The model used to describe how an event loop handles and processes	5209	The model used to describe how an event loop handles and processes
4712	watchers and events.	5210	watchers and events.
4713		5211
4714	=item pending	5212	=item pending
4715		5213
4716	A watcher is pending as soon as the corresponding event has been detected,	5214	A watcher is pending as soon as the corresponding event has been
4717	and stops being pending as soon as the watcher will be invoked or its	5215	detected. See L<WATCHER STATES> for details.
4718	pending status is explicitly cleared by the application.
4719
4720	A watcher can be pending, but not active. Stopping a watcher also clears
4721	its pending status.
4722		5216
4723	=item real time	5217	=item real time
4724		5218
4725	The physical time that is observed. It is apparently strictly monotonic :)	5219	The physical time that is observed. It is apparently strictly monotonic :)
4726		5220
…		…
4733	=item watcher	5227	=item watcher
4734		5228
4735	A data structure that describes interest in certain events. Watchers need	5229	A data structure that describes interest in certain events. Watchers need
4736	to be started (attached to an event loop) before they can receive events.	5230	to be started (attached to an event loop) before they can receive events.
4737		5231
4738	=item watcher invocation
4739
4740	The act of calling the callback associated with a watcher.
4741
4742	=back	5232	=back
4743		5233
4744	=head1 AUTHOR	5234	=head1 AUTHOR
4745		5235
4746	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson.	5236	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael
		5237	Magnusson and Emanuele Giaquinta.
4747		5238

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