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Comparing libev/ev.pod (file contents):
Revision 1.299 by sf-exg, Sat Aug 28 21:42:12 2010 UTC vs.
Revision 1.350 by sf-exg, Mon Jan 10 08:36:41 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	This flag's behaviour will become the default in future versions of libev.
387		448
388	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	449	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
389		450
390	This is your standard select(2) backend. Not I<completely> standard, as	451	This is your standard select(2) backend. Not I<completely> standard, as
391	libev tries to roll its own fd_set with no limits on the number of fds,	452	libev tries to roll its own fd_set with no limits on the number of fds,
…		…
427	epoll scales either O(1) or O(active_fds).	488	epoll scales either O(1) or O(active_fds).
428		489
429	The epoll mechanism deserves honorable mention as the most misdesigned	490	The epoll mechanism deserves honorable mention as the most misdesigned
430	of the more advanced event mechanisms: mere annoyances include silently	491	of the more advanced event mechanisms: mere annoyances include silently
431	dropping file descriptors, requiring a system call per change per file	492	dropping file descriptors, requiring a system call per change per file
432	descriptor (and unnecessary guessing of parameters), problems with dup and	493	descriptor (and unnecessary guessing of parameters), problems with dup,
		494	returning before the timeout value, resulting in additional iterations
		495	(and only giving 5ms accuracy while select on the same platform gives
433	so on. The biggest issue is fork races, however - if a program forks then	496	0.1ms) and so on. The biggest issue is fork races, however - if a program
434	I<both> parent and child process have to recreate the epoll set, which can	497	forks then I<both> parent and child process have to recreate the epoll
435	take considerable time (one syscall per file descriptor) and is of course	498	set, which can take considerable time (one syscall per file descriptor)
436	hard to detect.	499	and is of course hard to detect.
437		500
438	Epoll is also notoriously buggy - embedding epoll fds I<should> work, but	501	Epoll is also notoriously buggy - embedding epoll fds I<should> work, but
439	of course I<doesn't>, and epoll just loves to report events for totally	502	of course I<doesn't>, and epoll just loves to report events for totally
440	I<different> file descriptors (even already closed ones, so one cannot	503	I<different> file descriptors (even already closed ones, so one cannot
441	even remove them from the set) than registered in the set (especially	504	even remove them from the set) than registered in the set (especially
442	on SMP systems). Libev tries to counter these spurious notifications by	505	on SMP systems). Libev tries to counter these spurious notifications by
443	employing an additional generation counter and comparing that against the	506	employing an additional generation counter and comparing that against the
444	events to filter out spurious ones, recreating the set when required.	507	events to filter out spurious ones, recreating the set when required. Last
		508	not least, it also refuses to work with some file descriptors which work
		509	perfectly fine with C<select> (files, many character devices...).
		510
		511	Epoll is truly the train wreck analog among event poll mechanisms.
445		512
446	While stopping, setting and starting an I/O watcher in the same iteration	513	While stopping, setting and starting an I/O watcher in the same iteration
447	will result in some caching, there is still a system call per such	514	will result in some caching, there is still a system call per such
448	incident (because the same I<file descriptor> could point to a different	515	incident (because the same I<file descriptor> could point to a different
449	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed	516	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed
…		…
538		605
539	Try all backends (even potentially broken ones that wouldn't be tried	606	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	607	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as
541	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.	608	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.
542		609
543	It is definitely not recommended to use this flag.	610	It is definitely not recommended to use this flag, use whatever
		611	C<ev_recommended_backends ()> returns, or simply do not specify a backend
		612	at all.
		613
		614	=item C<EVBACKEND_MASK>
		615
		616	Not a backend at all, but a mask to select all backend bits from a
		617	C<flags> value, in case you want to mask out any backends from a flags
		618	value (e.g. when modifying the C<LIBEV_FLAGS> environment variable).
544		619
545	=back	620	=back
546		621
547	If one or more of the backend flags are or'ed into the flags value,	622	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	623	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	624	here). If none are specified, all backends in C<ev_recommended_backends
550	()> will be tried.	625	()> will be tried.
551		626
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.	627	Example: Try to create a event loop that uses epoll and nothing else.
579		628
580	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	629	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
581	if (!epoller)	630	if (!epoller)
582	fatal ("no epoll found here, maybe it hides under your chair");	631	fatal ("no epoll found here, maybe it hides under your chair");
583		632
		633	Example: Use whatever libev has to offer, but make sure that kqueue is
		634	used if available.
		635
		636	struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE);
		637
584	=item ev_default_destroy ()	638	=item ev_loop_destroy (loop)
585		639
586	Destroys the default loop (frees all memory and kernel state etc.). None	640	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	641	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	642	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,	643	responsibility to either stop all watchers cleanly yourself I<before>
590	or cope with the fact afterwards (which is usually the easiest thing, you	644	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).	645	the easiest thing, you can just ignore the watchers and/or C<free ()> them
		646	for example).
592		647
593	Note that certain global state, such as signal state (and installed signal	648	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	649	handlers), will not be freed by this function, and related watchers (such
595	as signal and child watchers) would need to be stopped manually.	650	as signal and child watchers) would need to be stopped manually.
596		651
597	In general it is not advisable to call this function except in the	652	This function is normally used on loop objects allocated by
598	rare occasion where you really need to free e.g. the signal handling	653	C<ev_loop_new>, but it can also be used on the default loop returned by
		654	C<ev_default_loop>, in which case it is not thread-safe.
		655
		656	Note that it is not advisable to call this function on the default loop
		657	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	658	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>.	659	and C<ev_loop_destroy>.
601		660
602	=item ev_loop_destroy (loop)	661	=item ev_loop_fork (loop)
603		662
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	663	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	664	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	665	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	666	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	667	child before resuming or calling C<ev_run>.
614	functions, and it will only take effect at the next C<ev_loop> iteration.
615		668
616	Again, you I<have> to call it on I<any> loop that you want to re-use after	669	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	670	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	671	because some kernel interfaces *cough* I<kqueue> *cough* do funny things
619	during fork.	672	during fork.
620		673
621	On the other hand, you only need to call this function in the child	674	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	675	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	676	you just fork+exec or create a new loop in the child, you don't have to
624	it at all.	677	call it at all (in fact, C<epoll> is so badly broken that it makes a
		678	difference, but libev will usually detect this case on its own and do a
		679	costly reset of the backend).
625		680
626	The function itself is quite fast and it's usually not a problem to call	681	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	682	it just in case after a fork.
628	quite nicely into a call to C<pthread_atfork>:
629		683
		684	Example: Automate calling C<ev_loop_fork> on the default loop when
		685	using pthreads.
		686
		687	static void
		688	post_fork_child (void)
		689	{
		690	ev_loop_fork (EV_DEFAULT);
		691	}
		692
		693	...
630	pthread_atfork (0, 0, ev_default_fork);	694	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		695
639	=item int ev_is_default_loop (loop)	696	=item int ev_is_default_loop (loop)
640		697
641	Returns true when the given loop is, in fact, the default loop, and false	698	Returns true when the given loop is, in fact, the default loop, and false
642	otherwise.	699	otherwise.
643		700
644	=item unsigned int ev_iteration (loop)	701	=item unsigned int ev_iteration (loop)
645		702
646	Returns the current iteration count for the loop, which is identical to	703	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	704	to the number of times libev did poll for new events. It starts at C<0>
648	happily wraps around with enough iterations.	705	and happily wraps around with enough iterations.
649		706
650	This value can sometimes be useful as a generation counter of sorts (it	707	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	708	"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	709	C<ev_prepare> and C<ev_check> calls - and is incremented between the
653	prepare and check phases.	710	prepare and check phases.
654		711
655	=item unsigned int ev_depth (loop)	712	=item unsigned int ev_depth (loop)
656		713
657	Returns the number of times C<ev_loop> was entered minus the number of	714	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.	715	times C<ev_run> was exited normally, in other words, the recursion depth.
659		716
660	Outside C<ev_loop>, this number is zero. In a callback, this number is	717	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),	718	C<1>, unless C<ev_run> was invoked recursively (or from another thread),
662	in which case it is higher.	719	in which case it is higher.
663		720
664	Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread	721	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	722	throwing an exception etc.), doesn't count as "exit" - consider this
666	ungentleman behaviour unless it's really convenient.	723	as a hint to avoid such ungentleman-like behaviour unless it's really
		724	convenient, in which case it is fully supported.
667		725
668	=item unsigned int ev_backend (loop)	726	=item unsigned int ev_backend (loop)
669		727
670	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	728	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
671	use.	729	use.
…		…
680		738
681	=item ev_now_update (loop)	739	=item ev_now_update (loop)
682		740
683	Establishes the current time by querying the kernel, updating the time	741	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	742	returned by C<ev_now ()> in the progress. This is a costly operation and
685	is usually done automatically within C<ev_loop ()>.	743	is usually done automatically within C<ev_run ()>.
686		744
687	This function is rarely useful, but when some event callback runs for a	745	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	746	very long time without entering the event loop, updating libev's idea of
689	the current time is a good idea.	747	the current time is a good idea.
690		748
…		…
692		750
693	=item ev_suspend (loop)	751	=item ev_suspend (loop)
694		752
695	=item ev_resume (loop)	753	=item ev_resume (loop)
696		754
697	These two functions suspend and resume a loop, for use when the loop is	755	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.	756	loop is not used for a while and timeouts should not be processed.
699		757
700	A typical use case would be an interactive program such as a game: When	758	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	759	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	760	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>	761	the program was suspended. This can be achieved by calling C<ev_suspend>
…		…
714	without a previous call to C<ev_suspend>.	772	without a previous call to C<ev_suspend>.
715		773
716	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the	774	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the
717	event loop time (see C<ev_now_update>).	775	event loop time (see C<ev_now_update>).
718		776
719	=item ev_loop (loop, int flags)	777	=item ev_run (loop, int flags)
720		778
721	Finally, this is it, the event handler. This function usually is called	779	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	780	after you have initialised all your watchers and you want to start
723	handling events.	781	handling events. It will ask the operating system for any new events, call
		782	the watcher callbacks, an then repeat the whole process indefinitely: This
		783	is why event loops are called I<loops>.
724		784
725	If the flags argument is specified as C<0>, it will not return until	785	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.	786	until either no event watchers are active anymore or C<ev_break> was
		787	called.
727		788
728	Please note that an explicit C<ev_unloop> is usually better than	789	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	790	relying on all watchers to be stopped when deciding when a program has
730	finished (especially in interactive programs), but having a program	791	finished (especially in interactive programs), but having a program
731	that automatically loops as long as it has to and no longer by virtue	792	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	793	of relying on its watchers stopping correctly, that is truly a thing of
733	beauty.	794	beauty.
734		795
		796	This function is also I<mostly> exception-safe - you can break out of
		797	a C<ev_run> call by calling C<longjmp> in a callback, throwing a C++
		798	exception and so on. This does not decrement the C<ev_depth> value, nor
		799	will it clear any outstanding C<EVBREAK_ONE> breaks.
		800
735	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle	801	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	802	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	803	block your process in case there are no events and will return after one
738	the loop.	804	iteration of the loop. This is sometimes useful to poll and handle new
		805	events while doing lengthy calculations, to keep the program responsive.
739		806
740	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if	807	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	808	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	809	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	810	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	811	user-registered callback will be called), and will return after one
745	iteration of the loop.	812	iteration of the loop.
746		813
747	This is useful if you are waiting for some external event in conjunction	814	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	815	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	816	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.	817	usually a better approach for this kind of thing.
751		818
752	Here are the gory details of what C<ev_loop> does:	819	Here are the gory details of what C<ev_run> does:
753		820
		821	- Increment loop depth.
		822	- Reset the ev_break status.
754	- Before the first iteration, call any pending watchers.	823	- Before the first iteration, call any pending watchers.
		824	LOOP:
755	* If EVFLAG_FORKCHECK was used, check for a fork.	825	- If EVFLAG_FORKCHECK was used, check for a fork.
756	- If a fork was detected (by any means), queue and call all fork watchers.	826	- If a fork was detected (by any means), queue and call all fork watchers.
757	- Queue and call all prepare watchers.	827	- Queue and call all prepare watchers.
		828	- If ev_break was called, goto FINISH.
758	- If we have been forked, detach and recreate the kernel state	829	- If we have been forked, detach and recreate the kernel state
759	as to not disturb the other process.	830	as to not disturb the other process.
760	- Update the kernel state with all outstanding changes.	831	- Update the kernel state with all outstanding changes.
761	- Update the "event loop time" (ev_now ()).	832	- Update the "event loop time" (ev_now ()).
762	- Calculate for how long to sleep or block, if at all	833	- Calculate for how long to sleep or block, if at all
763	(active idle watchers, EVLOOP_NONBLOCK or not having	834	(active idle watchers, EVRUN_NOWAIT or not having
764	any active watchers at all will result in not sleeping).	835	any active watchers at all will result in not sleeping).
765	- Sleep if the I/O and timer collect interval say so.	836	- Sleep if the I/O and timer collect interval say so.
		837	- Increment loop iteration counter.
766	- Block the process, waiting for any events.	838	- Block the process, waiting for any events.
767	- Queue all outstanding I/O (fd) events.	839	- Queue all outstanding I/O (fd) events.
768	- Update the "event loop time" (ev_now ()), and do time jump adjustments.	840	- Update the "event loop time" (ev_now ()), and do time jump adjustments.
769	- Queue all expired timers.	841	- Queue all expired timers.
770	- Queue all expired periodics.	842	- Queue all expired periodics.
771	- Unless any events are pending now, queue all idle watchers.	843	- Queue all idle watchers with priority higher than that of pending events.
772	- Queue all check watchers.	844	- Queue all check watchers.
773	- Call all queued watchers in reverse order (i.e. check watchers first).	845	- 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	846	Signals and child watchers are implemented as I/O watchers, and will
775	be handled here by queueing them when their watcher gets executed.	847	be handled here by queueing them when their watcher gets executed.
776	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	848	- If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT
777	were used, or there are no active watchers, return, otherwise	849	were used, or there are no active watchers, goto FINISH, otherwise
778	continue with step *.	850	continue with step LOOP.
		851	FINISH:
		852	- Reset the ev_break status iff it was EVBREAK_ONE.
		853	- Decrement the loop depth.
		854	- Return.
779		855
780	Example: Queue some jobs and then loop until no events are outstanding	856	Example: Queue some jobs and then loop until no events are outstanding
781	anymore.	857	anymore.
782		858
783	... queue jobs here, make sure they register event watchers as long	859	... 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..)	860	... as they still have work to do (even an idle watcher will do..)
785	ev_loop (my_loop, 0);	861	ev_run (my_loop, 0);
786	... jobs done or somebody called unloop. yeah!	862	... jobs done or somebody called unloop. yeah!
787		863
788	=item ev_unloop (loop, how)	864	=item ev_break (loop, how)
789		865
790	Can be used to make a call to C<ev_loop> return early (but only after it	866	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	867	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	868	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.	869	C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return.
794		870
795	This "unloop state" will be cleared when entering C<ev_loop> again.	871	This "break state" will be cleared on the next call to C<ev_run>.
796		872
797	It is safe to call C<ev_unloop> from outside any C<ev_loop> calls.	873	It is safe to call C<ev_break> from outside any C<ev_run> calls, too, in
		874	which case it will have no effect.
798		875
799	=item ev_ref (loop)	876	=item ev_ref (loop)
800		877
801	=item ev_unref (loop)	878	=item ev_unref (loop)
802		879
803	Ref/unref can be used to add or remove a reference count on the event	880	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	881	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.	882	count is nonzero, C<ev_run> will not return on its own.
806		883
807	This is useful when you have a watcher that you never intend to	884	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	885	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>	886	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>
810	before stopping it.	887	before stopping it.
811		888
812	As an example, libev itself uses this for its internal signal pipe: It	889	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	890	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	891	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	892	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	893	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	894	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	895	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>	896	(e.g. non-repeating timers) in which case you have to C<ev_ref>
820	in the callback).	897	in the callback).
821		898
822	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	899	Example: Create a signal watcher, but keep it from keeping C<ev_run>
823	running when nothing else is active.	900	running when nothing else is active.
824		901
825	ev_signal exitsig;	902	ev_signal exitsig;
826	ev_signal_init (&exitsig, sig_cb, SIGINT);	903	ev_signal_init (&exitsig, sig_cb, SIGINT);
827	ev_signal_start (loop, &exitsig);	904	ev_signal_start (loop, &exitsig);
828	evf_unref (loop);	905	ev_unref (loop);
829		906
830	Example: For some weird reason, unregister the above signal handler again.	907	Example: For some weird reason, unregister the above signal handler again.
831		908
832	ev_ref (loop);	909	ev_ref (loop);
833	ev_signal_stop (loop, &exitsig);	910	ev_signal_stop (loop, &exitsig);
…		…
890	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);	967	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);
891		968
892	=item ev_invoke_pending (loop)	969	=item ev_invoke_pending (loop)
893		970
894	This call will simply invoke all pending watchers while resetting their	971	This call will simply invoke all pending watchers while resetting their
895	pending state. Normally, C<ev_loop> does this automatically when required,	972	pending state. Normally, C<ev_run> does this automatically when required,
896	but when overriding the invoke callback this call comes handy.	973	but when overriding the invoke callback this call comes handy. This
		974	function can be invoked from a watcher - this can be useful for example
		975	when you want to do some lengthy calculation and want to pass further
		976	event handling to another thread (you still have to make sure only one
		977	thread executes within C<ev_invoke_pending> or C<ev_run> of course).
897		978
898	=item int ev_pending_count (loop)	979	=item int ev_pending_count (loop)
899		980
900	Returns the number of pending watchers - zero indicates that no watchers	981	Returns the number of pending watchers - zero indicates that no watchers
901	are pending.	982	are pending.
902		983
903	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))	984	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))
904		985
905	This overrides the invoke pending functionality of the loop: Instead of	986	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	987	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	988	this callback instead. This is useful, for example, when you want to
908	invoke the actual watchers inside another context (another thread etc.).	989	invoke the actual watchers inside another context (another thread etc.).
909		990
910	If you want to reset the callback, use C<ev_invoke_pending> as new	991	If you want to reset the callback, use C<ev_invoke_pending> as new
911	callback.	992	callback.
…		…
914		995
915	Sometimes you want to share the same loop between multiple threads. This	996	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	997	can be done relatively simply by putting mutex_lock/unlock calls around
917	each call to a libev function.	998	each call to a libev function.
918		999
919	However, C<ev_loop> can run an indefinite time, so it is not feasible to	1000	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	1001	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>	1002	loop via C<ev_break> and C<av_async_send>, another way is to set these
922	and I<acquire> callbacks on the loop.	1003	I<release> and I<acquire> callbacks on the loop.
923		1004
924	When set, then C<release> will be called just before the thread is	1005	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	1006	suspended waiting for new events, and C<acquire> is called just
926	afterwards.	1007	afterwards.
927		1008
…		…
930		1011
931	While event loop modifications are allowed between invocations of	1012	While event loop modifications are allowed between invocations of
932	C<release> and C<acquire> (that's their only purpose after all), no	1013	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	1014	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	1015	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	1016	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.	1017	to take note of any changes you made.
937		1018
938	In theory, threads executing C<ev_loop> will be async-cancel safe between	1019	In theory, threads executing C<ev_run> will be async-cancel safe between
939	invocations of C<release> and C<acquire>.	1020	invocations of C<release> and C<acquire>.
940		1021
941	See also the locking example in the C<THREADS> section later in this	1022	See also the locking example in the C<THREADS> section later in this
942	document.	1023	document.
943		1024
944	=item ev_set_userdata (loop, void *data)	1025	=item ev_set_userdata (loop, void *data)
945		1026
946	=item ev_userdata (loop)	1027	=item void *ev_userdata (loop)
947		1028
948	Set and retrieve a single C<void *> associated with a loop. When	1029	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	1030	C<ev_set_userdata> has never been called, then C<ev_userdata> returns
950	C<0.>	1031	C<0>.
951		1032
952	These two functions can be used to associate arbitrary data with a loop,	1033	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	1034	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	1035	C<acquire> callbacks described above, but of course can be (ab-)used for
955	any other purpose as well.	1036	any other purpose as well.
956		1037
957	=item ev_loop_verify (loop)	1038	=item ev_verify (loop)
958		1039
959	This function only does something when C<EV_VERIFY> support has been	1040	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	1041	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	1042	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	1043	is found to be inconsistent, it will print an error message to standard
…		…
973		1054
974	In the following description, uppercase C<TYPE> in names stands for the	1055	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	1056	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.	1057	watchers and C<ev_io_start> for I/O watchers.
977		1058
978	A watcher is a structure that you create and register to record your	1059	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	1060	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:	1061	to wait for STDIN to become readable, you would create an C<ev_io> watcher
		1062	for that:
981		1063
982	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)	1064	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)
983	{	1065	{
984	ev_io_stop (w);	1066	ev_io_stop (w);
985	ev_unloop (loop, EVUNLOOP_ALL);	1067	ev_break (loop, EVBREAK_ALL);
986	}	1068	}
987		1069
988	struct ev_loop *loop = ev_default_loop (0);	1070	struct ev_loop *loop = ev_default_loop (0);
989		1071
990	ev_io stdin_watcher;	1072	ev_io stdin_watcher;
991		1073
992	ev_init (&stdin_watcher, my_cb);	1074	ev_init (&stdin_watcher, my_cb);
993	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	1075	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
994	ev_io_start (loop, &stdin_watcher);	1076	ev_io_start (loop, &stdin_watcher);
995		1077
996	ev_loop (loop, 0);	1078	ev_run (loop, 0);
997		1079
998	As you can see, you are responsible for allocating the memory for your	1080	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	1081	watcher structures (and it is I<usually> a bad idea to do this on the
1000	stack).	1082	stack).
1001		1083
1002	Each watcher has an associated watcher structure (called C<struct ev_TYPE>	1084	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).	1085	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).
1004		1086
1005	Each watcher structure must be initialised by a call to C<ev_init	1087	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	1088	*, 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	1089	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	1090	time the event loop detects that the file descriptor given is readable
1009	is readable and/or writable).	1091	and/or writable).
1010		1092
1011	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>	1093	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	1094	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<<	1095	is also a macro to combine initialisation and setting in one call: C<<
1014	ev_TYPE_init (watcher *, callback, ...) >>.	1096	ev_TYPE_init (watcher *, callback, ...) >>.
…		…
1065		1147
1066	=item C<EV_PREPARE>	1148	=item C<EV_PREPARE>
1067		1149
1068	=item C<EV_CHECK>	1150	=item C<EV_CHECK>
1069		1151
1070	All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts	1152	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	1153	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	1154	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	1155	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	1156	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	1157	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
1076	C<ev_loop> from blocking).	1158	C<ev_run> from blocking).
1077		1159
1078	=item C<EV_EMBED>	1160	=item C<EV_EMBED>
1079		1161
1080	The embedded event loop specified in the C<ev_embed> watcher needs attention.	1162	The embedded event loop specified in the C<ev_embed> watcher needs attention.
1081		1163
1082	=item C<EV_FORK>	1164	=item C<EV_FORK>
1083		1165
1084	The event loop has been resumed in the child process after fork (see	1166	The event loop has been resumed in the child process after fork (see
1085	C<ev_fork>).	1167	C<ev_fork>).
		1168
		1169	=item C<EV_CLEANUP>
		1170
		1171	The event loop is about to be destroyed (see C<ev_cleanup>).
1086		1172
1087	=item C<EV_ASYNC>	1173	=item C<EV_ASYNC>
1088		1174
1089	The given async watcher has been asynchronously notified (see C<ev_async>).	1175	The given async watcher has been asynchronously notified (see C<ev_async>).
1090		1176
…		…
1262		1348
1263	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related	1349	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related
1264	functions that do not need a watcher.	1350	functions that do not need a watcher.
1265		1351
1266	=back	1352	=back
1267
1268		1353
1269	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	1354	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
1270		1355
1271	Each watcher has, by default, a member C<void *data> that you can change	1356	Each watcher has, by default, a member C<void *data> that you can change
1272	and read at any time: libev will completely ignore it. This can be used	1357	and read at any time: libev will completely ignore it. This can be used
…		…
1328	t2_cb (EV_P_ ev_timer *w, int revents)	1413	t2_cb (EV_P_ ev_timer *w, int revents)
1329	{	1414	{
1330	struct my_biggy big = (struct my_biggy *)	1415	struct my_biggy big = (struct my_biggy *)
1331	(((char *)w) - offsetof (struct my_biggy, t2));	1416	(((char *)w) - offsetof (struct my_biggy, t2));
1332	}	1417	}
		1418
		1419	=head2 WATCHER STATES
		1420
		1421	There are various watcher states mentioned throughout this manual -
		1422	active, pending and so on. In this section these states and the rules to
		1423	transition between them will be described in more detail - and while these
		1424	rules might look complicated, they usually do "the right thing".
		1425
		1426	=over 4
		1427
		1428	=item initialiased
		1429
		1430	Before a watcher can be registered with the event looop it has to be
		1431	initialised. This can be done with a call to C<ev_TYPE_init>, or calls to
		1432	C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function.
		1433
		1434	In this state it is simply some block of memory that is suitable for use
		1435	in an event loop. It can be moved around, freed, reused etc. at will.
		1436
		1437	=item started/running/active
		1438
		1439	Once a watcher has been started with a call to C<ev_TYPE_start> it becomes
		1440	property of the event loop, and is actively waiting for events. While in
		1441	this state it cannot be accessed (except in a few documented ways), moved,
		1442	freed or anything else - the only legal thing is to keep a pointer to it,
		1443	and call libev functions on it that are documented to work on active watchers.
		1444
		1445	=item pending
		1446
		1447	If a watcher is active and libev determines that an event it is interested
		1448	in has occurred (such as a timer expiring), it will become pending. It will
		1449	stay in this pending state until either it is stopped or its callback is
		1450	about to be invoked, so it is not normally pending inside the watcher
		1451	callback.
		1452
		1453	The watcher might or might not be active while it is pending (for example,
		1454	an expired non-repeating timer can be pending but no longer active). If it
		1455	is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>),
		1456	but it is still property of the event loop at this time, so cannot be
		1457	moved, freed or reused. And if it is active the rules described in the
		1458	previous item still apply.
		1459
		1460	It is also possible to feed an event on a watcher that is not active (e.g.
		1461	via C<ev_feed_event>), in which case it becomes pending without being
		1462	active.
		1463
		1464	=item stopped
		1465
		1466	A watcher can be stopped implicitly by libev (in which case it might still
		1467	be pending), or explicitly by calling its C<ev_TYPE_stop> function. The
		1468	latter will clear any pending state the watcher might be in, regardless
		1469	of whether it was active or not, so stopping a watcher explicitly before
		1470	freeing it is often a good idea.
		1471
		1472	While stopped (and not pending) the watcher is essentially in the
		1473	initialised state, that is it can be reused, moved, modified in any way
		1474	you wish.
		1475
		1476	=back
1333		1477
1334	=head2 WATCHER PRIORITY MODELS	1478	=head2 WATCHER PRIORITY MODELS
1335		1479
1336	Many event loops support I<watcher priorities>, which are usually small	1480	Many event loops support I<watcher priorities>, which are usually small
1337	integers that influence the ordering of event callback invocation	1481	integers that influence the ordering of event callback invocation
…		…
1622	...	1766	...
1623	struct ev_loop *loop = ev_default_init (0);	1767	struct ev_loop *loop = ev_default_init (0);
1624	ev_io stdin_readable;	1768	ev_io stdin_readable;
1625	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1769	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1626	ev_io_start (loop, &stdin_readable);	1770	ev_io_start (loop, &stdin_readable);
1627	ev_loop (loop, 0);	1771	ev_run (loop, 0);
1628		1772
1629		1773
1630	=head2 C<ev_timer> - relative and optionally repeating timeouts	1774	=head2 C<ev_timer> - relative and optionally repeating timeouts
1631		1775
1632	Timer watchers are simple relative timers that generate an event after a	1776	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	1785	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	1786	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	1787	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	1788	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	1789	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).	1790	no longer true when a callback calls C<ev_run> recursively).
1647		1791
1648	=head3 Be smart about timeouts	1792	=head3 Be smart about timeouts
1649		1793
1650	Many real-world problems involve some kind of timeout, usually for error	1794	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,	1795	recovery. A typical example is an HTTP request - if the other side hangs,
…		…
1822		1966
1823	=head3 The special problem of time updates	1967	=head3 The special problem of time updates
1824		1968
1825	Establishing the current time is a costly operation (it usually takes at	1969	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	1970	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	1971	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	1972	growing difference between C<ev_now ()> and C<ev_time ()> when handling
1829	lots of events in one iteration.	1973	lots of events in one iteration.
1830		1974
1831	The relative timeouts are calculated relative to the C<ev_now ()>	1975	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	1976	time. This is usually the right thing as this timestamp refers to the time
…		…
1949	}	2093	}
1950		2094
1951	ev_timer mytimer;	2095	ev_timer mytimer;
1952	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	2096	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1953	ev_timer_again (&mytimer); /* start timer */	2097	ev_timer_again (&mytimer); /* start timer */
1954	ev_loop (loop, 0);	2098	ev_run (loop, 0);
1955		2099
1956	// and in some piece of code that gets executed on any "activity":	2100	// and in some piece of code that gets executed on any "activity":
1957	// reset the timeout to start ticking again at 10 seconds	2101	// reset the timeout to start ticking again at 10 seconds
1958	ev_timer_again (&mytimer);	2102	ev_timer_again (&mytimer);
1959		2103
…		…
1985		2129
1986	As with timers, the callback is guaranteed to be invoked only when the	2130	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	2131	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	2132	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	2133	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).	2134	(but this is no longer true when a callback calls C<ev_run> recursively).
1991		2135
1992	=head3 Watcher-Specific Functions and Data Members	2136	=head3 Watcher-Specific Functions and Data Members
1993		2137
1994	=over 4	2138	=over 4
1995		2139
…		…
2123	Example: Call a callback every hour, or, more precisely, whenever the	2267	Example: Call a callback every hour, or, more precisely, whenever the
2124	system time is divisible by 3600. The callback invocation times have	2268	system time is divisible by 3600. The callback invocation times have
2125	potentially a lot of jitter, but good long-term stability.	2269	potentially a lot of jitter, but good long-term stability.
2126		2270
2127	static void	2271	static void
2128	clock_cb (struct ev_loop *loop, ev_io *w, int revents)	2272	clock_cb (struct ev_loop *loop, ev_periodic *w, int revents)
2129	{	2273	{
2130	... its now a full hour (UTC, or TAI or whatever your clock follows)	2274	... its now a full hour (UTC, or TAI or whatever your clock follows)
2131	}	2275	}
2132		2276
2133	ev_periodic hourly_tick;	2277	ev_periodic hourly_tick;
…		…
2156		2300
2157	=head2 C<ev_signal> - signal me when a signal gets signalled!	2301	=head2 C<ev_signal> - signal me when a signal gets signalled!
2158		2302
2159	Signal watchers will trigger an event when the process receives a specific	2303	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	2304	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	2305	will try its best to deliver signals synchronously, i.e. as part of the
2162	normal event processing, like any other event.	2306	normal event processing, like any other event.
2163		2307
2164	If you want signals to be delivered truly asynchronously, just use	2308	If you want signals to be delivered truly asynchronously, just use
2165	C<sigaction> as you would do without libev and forget about sharing	2309	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	2310	the signal. You can even use C<ev_async> from a signal handler to
…		…
2209		2353
2210	So I can't stress this enough: I<If you do not reset your signal mask when	2354	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	2355	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.	2356	is not a libev-specific thing, this is true for most event libraries.
2213		2357
		2358	=head3 The special problem of threads signal handling
		2359
		2360	POSIX threads has problematic signal handling semantics, specifically,
		2361	a lot of functionality (sigfd, sigwait etc.) only really works if all
		2362	threads in a process block signals, which is hard to achieve.
		2363
		2364	When you want to use sigwait (or mix libev signal handling with your own
		2365	for the same signals), you can tackle this problem by globally blocking
		2366	all signals before creating any threads (or creating them with a fully set
		2367	sigprocmask) and also specifying the C<EVFLAG_NOSIGMASK> when creating
		2368	loops. Then designate one thread as "signal receiver thread" which handles
		2369	these signals. You can pass on any signals that libev might be interested
		2370	in by calling C<ev_feed_signal>.
		2371
2214	=head3 Watcher-Specific Functions and Data Members	2372	=head3 Watcher-Specific Functions and Data Members
2215		2373
2216	=over 4	2374	=over 4
2217		2375
2218	=item ev_signal_init (ev_signal *, callback, int signum)	2376	=item ev_signal_init (ev_signal *, callback, int signum)
…		…
2233	Example: Try to exit cleanly on SIGINT.	2391	Example: Try to exit cleanly on SIGINT.
2234		2392
2235	static void	2393	static void
2236	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)	2394	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)
2237	{	2395	{
2238	ev_unloop (loop, EVUNLOOP_ALL);	2396	ev_break (loop, EVBREAK_ALL);
2239	}	2397	}
2240		2398
2241	ev_signal signal_watcher;	2399	ev_signal signal_watcher;
2242	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	2400	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
2243	ev_signal_start (loop, &signal_watcher);	2401	ev_signal_start (loop, &signal_watcher);
…		…
2629		2787
2630	Prepare and check watchers are usually (but not always) used in pairs:	2788	Prepare and check watchers are usually (but not always) used in pairs:
2631	prepare watchers get invoked before the process blocks and check watchers	2789	prepare watchers get invoked before the process blocks and check watchers
2632	afterwards.	2790	afterwards.
2633		2791
2634	You I<must not> call C<ev_loop> or similar functions that enter	2792	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>	2793	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	2794	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	2795	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,	2796	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	2797	C<ev_check> so if you have one watcher of each kind they will always be
…		…
2807		2965
2808	if (timeout >= 0)	2966	if (timeout >= 0)
2809	// create/start timer	2967	// create/start timer
2810		2968
2811	// poll	2969	// poll
2812	ev_loop (EV_A_ 0);	2970	ev_run (EV_A_ 0);
2813		2971
2814	// stop timer again	2972	// stop timer again
2815	if (timeout >= 0)	2973	if (timeout >= 0)
2816	ev_timer_stop (EV_A_ &to);	2974	ev_timer_stop (EV_A_ &to);
2817		2975
…		…
2895	if you do not want that, you need to temporarily stop the embed watcher).	3053	if you do not want that, you need to temporarily stop the embed watcher).
2896		3054
2897	=item ev_embed_sweep (loop, ev_embed *)	3055	=item ev_embed_sweep (loop, ev_embed *)
2898		3056
2899	Make a single, non-blocking sweep over the embedded loop. This works	3057	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	3058	similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most
2901	appropriate way for embedded loops.	3059	appropriate way for embedded loops.
2902		3060
2903	=item struct ev_loop *other [read-only]	3061	=item struct ev_loop *other [read-only]
2904		3062
2905	The embedded event loop.	3063	The embedded event loop.
…		…
2965	C<ev_default_fork> cheats and calls it in the wrong process, the fork	3123	C<ev_default_fork> cheats and calls it in the wrong process, the fork
2966	handlers will be invoked, too, of course.	3124	handlers will be invoked, too, of course.
2967		3125
2968	=head3 The special problem of life after fork - how is it possible?	3126	=head3 The special problem of life after fork - how is it possible?
2969		3127
2970	Most uses of C<fork()> consist of forking, then some simple calls to ste	3128	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	3129	up/change the process environment, followed by a call to C<exec()>. This
2972	sequence should be handled by libev without any problems.	3130	sequence should be handled by libev without any problems.
2973		3131
2974	This changes when the application actually wants to do event handling	3132	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	3133	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	3149	disadvantage of having to use multiple event loops (which do not support
2992	signal watchers).	3150	signal watchers).
2993		3151
2994	When this is not possible, or you want to use the default loop for	3152	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	3153	other reasons, then in the process that wants to start "fresh", call
2996	C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying	3154	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	3155	Destroying the default loop will "orphan" (not stop) all registered
2998	have to be careful not to execute code that modifies those watchers. Note	3156	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.	3157	those watchers. Note also that in that case, you have to re-register any
		3158	signal watchers.
3000		3159
3001	=head3 Watcher-Specific Functions and Data Members	3160	=head3 Watcher-Specific Functions and Data Members
3002		3161
3003	=over 4	3162	=over 4
3004		3163
3005	=item ev_fork_init (ev_signal *, callback)	3164	=item ev_fork_init (ev_fork *, callback)
3006		3165
3007	Initialises and configures the fork watcher - it has no parameters of any	3166	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,	3167	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
3009	believe me.	3168	really.
3010		3169
3011	=back	3170	=back
3012		3171
3013		3172
		3173	=head2 C<ev_cleanup> - even the best things end
		3174
		3175	Cleanup watchers are called just before the event loop is being destroyed
		3176	by a call to C<ev_loop_destroy>.
		3177
		3178	While there is no guarantee that the event loop gets destroyed, cleanup
		3179	watchers provide a convenient method to install cleanup hooks for your
		3180	program, worker threads and so on - you just to make sure to destroy the
		3181	loop when you want them to be invoked.
		3182
		3183	Cleanup watchers are invoked in the same way as any other watcher. Unlike
		3184	all other watchers, they do not keep a reference to the event loop (which
		3185	makes a lot of sense if you think about it). Like all other watchers, you
		3186	can call libev functions in the callback, except C<ev_cleanup_start>.
		3187
		3188	=head3 Watcher-Specific Functions and Data Members
		3189
		3190	=over 4
		3191
		3192	=item ev_cleanup_init (ev_cleanup *, callback)
		3193
		3194	Initialises and configures the cleanup watcher - it has no parameters of
		3195	any kind. There is a C<ev_cleanup_set> macro, but using it is utterly
		3196	pointless, I assure you.
		3197
		3198	=back
		3199
		3200	Example: Register an atexit handler to destroy the default loop, so any
		3201	cleanup functions are called.
		3202
		3203	static void
		3204	program_exits (void)
		3205	{
		3206	ev_loop_destroy (EV_DEFAULT_UC);
		3207	}
		3208
		3209	...
		3210	atexit (program_exits);
		3211
		3212
3014	=head2 C<ev_async> - how to wake up another event loop	3213	=head2 C<ev_async> - how to wake up an event loop
3015		3214
3016	In general, you cannot use an C<ev_loop> from multiple threads or other	3215	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	3216	asynchronous sources such as signal handlers (as opposed to multiple event
3018	loops - those are of course safe to use in different threads).	3217	loops - those are of course safe to use in different threads).
3019		3218
3020	Sometimes, however, you need to wake up another event loop you do not	3219	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	3220	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	3221	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	3222	it by calling C<ev_async_send>, which is thread- and signal safe.
3024	safe.
3025		3223
3026	This functionality is very similar to C<ev_signal> watchers, as signals,	3224	This functionality is very similar to C<ev_signal> watchers, as signals,
3027	too, are asynchronous in nature, and signals, too, will be compressed	3225	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	3226	(i.e. the number of callback invocations may be less than the number of
3029	C<ev_async_sent> calls).	3227	C<ev_async_sent> calls). In fact, you could use signal watchers as a kind
		3228	of "global async watchers" by using a watcher on an otherwise unused
		3229	signal, and C<ev_feed_signal> to signal this watcher from another thread,
		3230	even without knowing which loop owns the signal.
3030		3231
3031	Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not	3232	Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not
3032	just the default loop.	3233	just the default loop.
3033		3234
3034	=head3 Queueing	3235	=head3 Queueing
…		…
3210	Feed an event on the given fd, as if a file descriptor backend detected	3411	Feed an event on the given fd, as if a file descriptor backend detected
3211	the given events it.	3412	the given events it.
3212		3413
3213	=item ev_feed_signal_event (loop, int signum)	3414	=item ev_feed_signal_event (loop, int signum)
3214		3415
3215	Feed an event as if the given signal occurred (C<loop> must be the default	3416	Feed an event as if the given signal occurred. See also C<ev_feed_signal>,
3216	loop!).	3417	which is async-safe.
		3418
		3419	=back
		3420
		3421
		3422	=head1 COMMON OR USEFUL IDIOMS (OR BOTH)
		3423
		3424	This section explains some common idioms that are not immediately
		3425	obvious. Note that examples are sprinkled over the whole manual, and this
		3426	section only contains stuff that wouldn't fit anywhere else.
		3427
		3428	=over 4
		3429
		3430	=item Model/nested event loop invocations and exit conditions.
		3431
		3432	Often (especially in GUI toolkits) there are places where you have
		3433	I<modal> interaction, which is most easily implemented by recursively
		3434	invoking C<ev_run>.
		3435
		3436	This brings the problem of exiting - a callback might want to finish the
		3437	main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but
		3438	a modal "Are you sure?" dialog is still waiting), or just the nested one
		3439	and not the main one (e.g. user clocked "Ok" in a modal dialog), or some
		3440	other combination: In these cases, C<ev_break> will not work alone.
		3441
		3442	The solution is to maintain "break this loop" variable for each C<ev_run>
		3443	invocation, and use a loop around C<ev_run> until the condition is
		3444	triggered, using C<EVRUN_ONCE>:
		3445
		3446	// main loop
		3447	int exit_main_loop = 0;
		3448
		3449	while (!exit_main_loop)
		3450	ev_run (EV_DEFAULT_ EVRUN_ONCE);
		3451
		3452	// in a model watcher
		3453	int exit_nested_loop = 0;
		3454
		3455	while (!exit_nested_loop)
		3456	ev_run (EV_A_ EVRUN_ONCE);
		3457
		3458	To exit from any of these loops, just set the corresponding exit variable:
		3459
		3460	// exit modal loop
		3461	exit_nested_loop = 1;
		3462
		3463	// exit main program, after modal loop is finished
		3464	exit_main_loop = 1;
		3465
		3466	// exit both
		3467	exit_main_loop = exit_nested_loop = 1;
3217		3468
3218	=back	3469	=back
3219		3470
3220		3471
3221	=head1 LIBEVENT EMULATION	3472	=head1 LIBEVENT EMULATION
3222		3473
3223	Libev offers a compatibility emulation layer for libevent. It cannot	3474	Libev offers a compatibility emulation layer for libevent. It cannot
3224	emulate the internals of libevent, so here are some usage hints:	3475	emulate the internals of libevent, so here are some usage hints:
3225		3476
3226	=over 4	3477	=over 4
		3478
		3479	=item * Only the libevent-1.4.1-beta API is being emulated.
		3480
		3481	This was the newest libevent version available when libev was implemented,
		3482	and is still mostly unchanged in 2010.
3227		3483
3228	=item * Use it by including <event.h>, as usual.	3484	=item * Use it by including <event.h>, as usual.
3229		3485
3230	=item * The following members are fully supported: ev_base, ev_callback,	3486	=item * The following members are fully supported: ev_base, ev_callback,
3231	ev_arg, ev_fd, ev_res, ev_events.	3487	ev_arg, ev_fd, ev_res, ev_events.
…		…
3237	=item * Priorities are not currently supported. Initialising priorities	3493	=item * Priorities are not currently supported. Initialising priorities
3238	will fail and all watchers will have the same priority, even though there	3494	will fail and all watchers will have the same priority, even though there
3239	is an ev_pri field.	3495	is an ev_pri field.
3240		3496
3241	=item * In libevent, the last base created gets the signals, in libev, the	3497	=item * In libevent, the last base created gets the signals, in libev, the
3242	first base created (== the default loop) gets the signals.	3498	base that registered the signal gets the signals.
3243		3499
3244	=item * Other members are not supported.	3500	=item * Other members are not supported.
3245		3501
3246	=item * The libev emulation is I<not> ABI compatible to libevent, you need	3502	=item * The libev emulation is I<not> ABI compatible to libevent, you need
3247	to use the libev header file and library.	3503	to use the libev header file and library.
…		…
3266	Care has been taken to keep the overhead low. The only data member the C++	3522	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	3523	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	3524	that the watcher is associated with (or no additional members at all if
3269	you disable C<EV_MULTIPLICITY> when embedding libev).	3525	you disable C<EV_MULTIPLICITY> when embedding libev).
3270		3526
3271	Currently, functions, and static and non-static member functions can be	3527	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	3528	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	3529	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	3530	you need support for other types of functors please contact the author
3275	it).	3531	(preferably after implementing it).
3276		3532
3277	Here is a list of things available in the C<ev> namespace:	3533	Here is a list of things available in the C<ev> namespace:
3278		3534
3279	=over 4	3535	=over 4
3280		3536
…		…
3390	Associates a different C<struct ev_loop> with this watcher. You can only	3646	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).	3647	do this when the watcher is inactive (and not pending either).
3392		3648
3393	=item w->set ([arguments])	3649	=item w->set ([arguments])
3394		3650
3395	Basically the same as C<ev_TYPE_set>, with the same arguments. Must be	3651	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	3652	method or a suitable start method must be called at least once. Unlike the
3397	automatically stopped and restarted when reconfiguring it with this	3653	C counterpart, an active watcher gets automatically stopped and restarted
3398	method.	3654	when reconfiguring it with this method.
3399		3655
3400	=item w->start ()	3656	=item w->start ()
3401		3657
3402	Starts the watcher. Note that there is no C<loop> argument, as the	3658	Starts the watcher. Note that there is no C<loop> argument, as the
3403	constructor already stores the event loop.	3659	constructor already stores the event loop.
3404		3660
		3661	=item w->start ([arguments])
		3662
		3663	Instead of calling C<set> and C<start> methods separately, it is often
		3664	convenient to wrap them in one call. Uses the same type of arguments as
		3665	the configure C<set> method of the watcher.
		3666
3405	=item w->stop ()	3667	=item w->stop ()
3406		3668
3407	Stops the watcher if it is active. Again, no C<loop> argument.	3669	Stops the watcher if it is active. Again, no C<loop> argument.
3408		3670
3409	=item w->again () (C<ev::timer>, C<ev::periodic> only)	3671	=item w->again () (C<ev::timer>, C<ev::periodic> only)
…		…
3421		3683
3422	=back	3684	=back
3423		3685
3424	=back	3686	=back
3425		3687
3426	Example: Define a class with an IO and idle watcher, start one of them in	3688	Example: Define a class with two I/O and idle watchers, start the I/O
3427	the constructor.	3689	watchers in the constructor.
3428		3690
3429	class myclass	3691	class myclass
3430	{	3692	{
3431	ev::io io ; void io_cb (ev::io &w, int revents);	3693	ev::io io ; void io_cb (ev::io &w, int revents);
		3694	ev::io2 io2 ; void io2_cb (ev::io &w, int revents);
3432	ev::idle idle; void idle_cb (ev::idle &w, int revents);	3695	ev::idle idle; void idle_cb (ev::idle &w, int revents);
3433		3696
3434	myclass (int fd)	3697	myclass (int fd)
3435	{	3698	{
3436	io .set <myclass, &myclass::io_cb > (this);	3699	io .set <myclass, &myclass::io_cb > (this);
		3700	io2 .set <myclass, &myclass::io2_cb > (this);
3437	idle.set <myclass, &myclass::idle_cb> (this);	3701	idle.set <myclass, &myclass::idle_cb> (this);
3438		3702
3439	io.start (fd, ev::READ);	3703	io.set (fd, ev::WRITE); // configure the watcher
		3704	io.start (); // start it whenever convenient
		3705
		3706	io2.start (fd, ev::READ); // set + start in one call
3440	}	3707	}
3441	};	3708	};
3442		3709
3443		3710
3444	=head1 OTHER LANGUAGE BINDINGS	3711	=head1 OTHER LANGUAGE BINDINGS
…		…
3518	loop argument"). The C<EV_A> form is used when this is the sole argument,	3785	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:	3786	C<EV_A_> is used when other arguments are following. Example:
3520		3787
3521	ev_unref (EV_A);	3788	ev_unref (EV_A);
3522	ev_timer_add (EV_A_ watcher);	3789	ev_timer_add (EV_A_ watcher);
3523	ev_loop (EV_A_ 0);	3790	ev_run (EV_A_ 0);
3524		3791
3525	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	3792	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
3526	which is often provided by the following macro.	3793	which is often provided by the following macro.
3527		3794
3528	=item C<EV_P>, C<EV_P_>	3795	=item C<EV_P>, C<EV_P_>
…		…
3568	}	3835	}
3569		3836
3570	ev_check check;	3837	ev_check check;
3571	ev_check_init (&check, check_cb);	3838	ev_check_init (&check, check_cb);
3572	ev_check_start (EV_DEFAULT_ &check);	3839	ev_check_start (EV_DEFAULT_ &check);
3573	ev_loop (EV_DEFAULT_ 0);	3840	ev_run (EV_DEFAULT_ 0);
3574		3841
3575	=head1 EMBEDDING	3842	=head1 EMBEDDING
3576		3843
3577	Libev can (and often is) directly embedded into host	3844	Libev can (and often is) directly embedded into host
3578	applications. Examples of applications that embed it include the Deliantra	3845	applications. Examples of applications that embed it include the Deliantra
…		…
3669	to a compiled library. All other symbols change the ABI, which means all	3936	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	3937	users of libev and the libev code itself must be compiled with compatible
3671	settings.	3938	settings.
3672		3939
3673	=over 4	3940	=over 4
		3941
		3942	=item EV_COMPAT3 (h)
		3943
		3944	Backwards compatibility is a major concern for libev. This is why this
		3945	release of libev comes with wrappers for the functions and symbols that
		3946	have been renamed between libev version 3 and 4.
		3947
		3948	You can disable these wrappers (to test compatibility with future
		3949	versions) by defining C<EV_COMPAT3> to C<0> when compiling your
		3950	sources. This has the additional advantage that you can drop the C<struct>
		3951	from C<struct ev_loop> declarations, as libev will provide an C<ev_loop>
		3952	typedef in that case.
		3953
		3954	In some future version, the default for C<EV_COMPAT3> will become C<0>,
		3955	and in some even more future version the compatibility code will be
		3956	removed completely.
3674		3957
3675	=item EV_STANDALONE (h)	3958	=item EV_STANDALONE (h)
3676		3959
3677	Must always be C<1> if you do not use autoconf configuration, which	3960	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	3961	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	4311	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
4029	will be C<0>.	4312	will be C<0>.
4030		4313
4031	=item EV_VERIFY	4314	=item EV_VERIFY
4032		4315
4033	Controls how much internal verification (see C<ev_loop_verify ()>) will	4316	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	4317	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	4318	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	4319	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	4320	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	4321	verification code will be called very frequently, which will slow down
…		…
4042	will be C<0>.	4325	will be C<0>.
4043		4326
4044	=item EV_COMMON	4327	=item EV_COMMON
4045		4328
4046	By default, all watchers have a C<void *data> member. By redefining	4329	By default, all watchers have a C<void *data> member. By redefining
4047	this macro to a something else you can include more and other types of	4330	this macro to something else you can include more and other types of
4048	members. You have to define it each time you include one of the files,	4331	members. You have to define it each time you include one of the files,
4049	though, and it must be identical each time.	4332	though, and it must be identical each time.
4050		4333
4051	For example, the perl EV module uses something like this:	4334	For example, the perl EV module uses something like this:
4052		4335
…		…
4253	userdata *u = ev_userdata (EV_A);	4536	userdata *u = ev_userdata (EV_A);
4254	pthread_mutex_lock (&u->lock);	4537	pthread_mutex_lock (&u->lock);
4255	}	4538	}
4256		4539
4257	The event loop thread first acquires the mutex, and then jumps straight	4540	The event loop thread first acquires the mutex, and then jumps straight
4258	into C<ev_loop>:	4541	into C<ev_run>:
4259		4542
4260	void *	4543	void *
4261	l_run (void *thr_arg)	4544	l_run (void *thr_arg)
4262	{	4545	{
4263	struct ev_loop *loop = (struct ev_loop *)thr_arg;	4546	struct ev_loop *loop = (struct ev_loop *)thr_arg;
4264		4547
4265	l_acquire (EV_A);	4548	l_acquire (EV_A);
4266	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);	4549	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
4267	ev_loop (EV_A_ 0);	4550	ev_run (EV_A_ 0);
4268	l_release (EV_A);	4551	l_release (EV_A);
4269		4552
4270	return 0;	4553	return 0;
4271	}	4554	}
4272		4555
…		…
4324		4607
4325	=head3 COROUTINES	4608	=head3 COROUTINES
4326		4609
4327	Libev is very accommodating to coroutines ("cooperative threads"):	4610	Libev is very accommodating to coroutines ("cooperative threads"):
4328	libev fully supports nesting calls to its functions from different	4611	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	4612	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	4613	different coroutines, and switch freely between both coroutines running
4331	the loop, as long as you don't confuse yourself). The only exception is	4614	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.	4615	that you must not do this from C<ev_periodic> reschedule callbacks.
4333		4616
4334	Care has been taken to ensure that libev does not keep local state inside	4617	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	4618	C<ev_run>, and other calls do not usually allow for coroutine switches as
4336	they do not call any callbacks.	4619	they do not call any callbacks.
4337		4620
4338	=head2 COMPILER WARNINGS	4621	=head2 COMPILER WARNINGS
4339		4622
4340	Depending on your compiler and compiler settings, you might get no or a	4623	Depending on your compiler and compiler settings, you might get no or a
…		…
4351	maintainable.	4634	maintainable.
4352		4635
4353	And of course, some compiler warnings are just plain stupid, or simply	4636	And of course, some compiler warnings are just plain stupid, or simply
4354	wrong (because they don't actually warn about the condition their message	4637	wrong (because they don't actually warn about the condition their message
4355	seems to warn about). For example, certain older gcc versions had some	4638	seems to warn about). For example, certain older gcc versions had some
4356	warnings that resulted an extreme number of false positives. These have	4639	warnings that resulted in an extreme number of false positives. These have
4357	been fixed, but some people still insist on making code warn-free with	4640	been fixed, but some people still insist on making code warn-free with
4358	such buggy versions.	4641	such buggy versions.
4359		4642
4360	While libev is written to generate as few warnings as possible,	4643	While libev is written to generate as few warnings as possible,
4361	"warn-free" code is not a goal, and it is recommended not to build libev	4644	"warn-free" code is not a goal, and it is recommended not to build libev
…		…
4397	I suggest using suppression lists.	4680	I suggest using suppression lists.
4398		4681
4399		4682
4400	=head1 PORTABILITY NOTES	4683	=head1 PORTABILITY NOTES
4401		4684
		4685	=head2 GNU/LINUX 32 BIT LIMITATIONS
		4686
		4687	GNU/Linux is the only common platform that supports 64 bit file/large file
		4688	interfaces but I<disables> them by default.
		4689
		4690	That means that libev compiled in the default environment doesn't support
		4691	files larger than 2GiB or so, which mainly affects C<ev_stat> watchers.
		4692
		4693	Unfortunately, many programs try to work around this GNU/Linux issue
		4694	by enabling the large file API, which makes them incompatible with the
		4695	standard libev compiled for their system.
		4696
		4697	Likewise, libev cannot enable the large file API itself as this would
		4698	suddenly make it incompatible to the default compile time environment,
		4699	i.e. all programs not using special compile switches.
		4700
		4701	=head2 OS/X AND DARWIN BUGS
		4702
		4703	The whole thing is a bug if you ask me - basically any system interface
		4704	you touch is broken, whether it is locales, poll, kqueue or even the
		4705	OpenGL drivers.
		4706
		4707	=head3 C<kqueue> is buggy
		4708
		4709	The kqueue syscall is broken in all known versions - most versions support
		4710	only sockets, many support pipes.
		4711
		4712	Libev tries to work around this by not using C<kqueue> by default on this
		4713	rotten platform, but of course you can still ask for it when creating a
		4714	loop - embedding a socket-only kqueue loop into a select-based one is
		4715	probably going to work well.
		4716
		4717	=head3 C<poll> is buggy
		4718
		4719	Instead of fixing C<kqueue>, Apple replaced their (working) C<poll>
		4720	implementation by something calling C<kqueue> internally around the 10.5.6
		4721	release, so now C<kqueue> I<and> C<poll> are broken.
		4722
		4723	Libev tries to work around this by not using C<poll> by default on
		4724	this rotten platform, but of course you can still ask for it when creating
		4725	a loop.
		4726
		4727	=head3 C<select> is buggy
		4728
		4729	All that's left is C<select>, and of course Apple found a way to fuck this
		4730	one up as well: On OS/X, C<select> actively limits the number of file
		4731	descriptors you can pass in to 1024 - your program suddenly crashes when
		4732	you use more.
		4733
		4734	There is an undocumented "workaround" for this - defining
		4735	C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should>
		4736	work on OS/X.
		4737
		4738	=head2 SOLARIS PROBLEMS AND WORKAROUNDS
		4739
		4740	=head3 C<errno> reentrancy
		4741
		4742	The default compile environment on Solaris is unfortunately so
		4743	thread-unsafe that you can't even use components/libraries compiled
		4744	without C<-D_REENTRANT> in a threaded program, which, of course, isn't
		4745	defined by default. A valid, if stupid, implementation choice.
		4746
		4747	If you want to use libev in threaded environments you have to make sure
		4748	it's compiled with C<_REENTRANT> defined.
		4749
		4750	=head3 Event port backend
		4751
		4752	The scalable event interface for Solaris is called "event
		4753	ports". Unfortunately, this mechanism is very buggy in all major
		4754	releases. If you run into high CPU usage, your program freezes or you get
		4755	a large number of spurious wakeups, make sure you have all the relevant
		4756	and latest kernel patches applied. No, I don't know which ones, but there
		4757	are multiple ones to apply, and afterwards, event ports actually work
		4758	great.
		4759
		4760	If you can't get it to work, you can try running the program by setting
		4761	the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and
		4762	C<select> backends.
		4763
		4764	=head2 AIX POLL BUG
		4765
		4766	AIX unfortunately has a broken C<poll.h> header. Libev works around
		4767	this by trying to avoid the poll backend altogether (i.e. it's not even
		4768	compiled in), which normally isn't a big problem as C<select> works fine
		4769	with large bitsets on AIX, and AIX is dead anyway.
		4770
4402	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS	4771	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
		4772
		4773	=head3 General issues
4403		4774
4404	Win32 doesn't support any of the standards (e.g. POSIX) that libev	4775	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	4776	requires, and its I/O model is fundamentally incompatible with the POSIX
4406	model. Libev still offers limited functionality on this platform in	4777	model. Libev still offers limited functionality on this platform in
4407	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	4778	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
4408	descriptors. This only applies when using Win32 natively, not when using	4779	descriptors. This only applies when using Win32 natively, not when using
4409	e.g. cygwin.	4780	e.g. cygwin. Actually, it only applies to the microsofts own compilers,
		4781	as every compielr comes with a slightly differently broken/incompatible
		4782	environment.
4410		4783
4411	Lifting these limitations would basically require the full	4784	Lifting these limitations would basically require the full
4412	re-implementation of the I/O system. If you are into these kinds of	4785	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	4786	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).	4787	also that glib is the slowest event library known to man).
4415		4788
4416	There is no supported compilation method available on windows except	4789	There is no supported compilation method available on windows except
4417	embedding it into other applications.	4790	embedding it into other applications.
4418		4791
4419	Sensible signal handling is officially unsupported by Microsoft - libev	4792	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!):	4820	you do I<not> compile the F<ev.c> or any other embedded source files!):
4448		4821
4449	#include "evwrap.h"	4822	#include "evwrap.h"
4450	#include "ev.c"	4823	#include "ev.c"
4451		4824
4452	=over 4
4453
4454	=item The winsocket select function	4825	=head3 The winsocket C<select> function
4455		4826
4456	The winsocket C<select> function doesn't follow POSIX in that it	4827	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	4828	requires socket I<handles> and not socket I<file descriptors> (it is
4458	also extremely buggy). This makes select very inefficient, and also	4829	also extremely buggy). This makes select very inefficient, and also
4459	requires a mapping from file descriptors to socket handles (the Microsoft	4830	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 */	4839	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
4469		4840
4470	Note that winsockets handling of fd sets is O(n), so you can easily get a	4841	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.	4842	complexity in the O(n²) range when using win32.
4472		4843
4473	=item Limited number of file descriptors	4844	=head3 Limited number of file descriptors
4474		4845
4475	Windows has numerous arbitrary (and low) limits on things.	4846	Windows has numerous arbitrary (and low) limits on things.
4476		4847
4477	Early versions of winsocket's select only supported waiting for a maximum	4848	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	4849	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	4864	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,	4865	(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	4866	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.	4867	the cost of calling select (O(n²)) will likely make this unworkable.
4497		4868
4498	=back
4499
4500	=head2 PORTABILITY REQUIREMENTS	4869	=head2 PORTABILITY REQUIREMENTS
4501		4870
4502	In addition to a working ISO-C implementation and of course the	4871	In addition to a working ISO-C implementation and of course the
4503	backend-specific APIs, libev relies on a few additional extensions:	4872	backend-specific APIs, libev relies on a few additional extensions:
4504		4873
…		…
4510	Libev assumes not only that all watcher pointers have the same internal	4879	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	4880	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	4881	assumes that the same (machine) code can be used to call any watcher
4513	callback: The watcher callbacks have different type signatures, but libev	4882	callback: The watcher callbacks have different type signatures, but libev
4514	calls them using an C<ev_watcher *> internally.	4883	calls them using an C<ev_watcher *> internally.
		4884
		4885	=item pointer accesses must be thread-atomic
		4886
		4887	Accessing a pointer value must be atomic, it must both be readable and
		4888	writable in one piece - this is the case on all current architectures.
4515		4889
4516	=item C<sig_atomic_t volatile> must be thread-atomic as well	4890	=item C<sig_atomic_t volatile> must be thread-atomic as well
4517		4891
4518	The type C<sig_atomic_t volatile> (or whatever is defined as	4892	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	4893	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different
…		…
4542	watchers.	4916	watchers.
4543		4917
4544	=item C<double> must hold a time value in seconds with enough accuracy	4918	=item C<double> must hold a time value in seconds with enough accuracy
4545		4919
4546	The type C<double> is used to represent timestamps. It is required to	4920	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	4921	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	4922	good enough for at least into the year 4000 with millisecond accuracy
		4923	(the design goal for libev). This requirement is overfulfilled by
4549	implementations implementing IEEE 754, which is basically all existing	4924	implementations using IEEE 754, which is basically all existing ones. With
4550	ones. With IEEE 754 doubles, you get microsecond accuracy until at least	4925	IEEE 754 doubles, you get microsecond accuracy until at least 2200.
4551	2200.
4552		4926
4553	=back	4927	=back
4554		4928
4555	If you know of other additional requirements drop me a note.	4929	If you know of other additional requirements drop me a note.
4556		4930
…		…
4626	=back	5000	=back
4627		5001
4628		5002
4629	=head1 PORTING FROM LIBEV 3.X TO 4.X	5003	=head1 PORTING FROM LIBEV 3.X TO 4.X
4630		5004
4631	The major version 4 introduced some minor incompatible changes to the API.	5005	The major version 4 introduced some incompatible changes to the API.
4632		5006
4633	At the moment, the C<ev.h> header file tries to implement superficial	5007	At the moment, the C<ev.h> header file provides compatibility definitions
4634	compatibility, so most programs should still compile. Those might be	5008	for all changes, so most programs should still compile. The compatibility
4635	removed in later versions of libev, so better update early than late.	5009	layer might be removed in later versions of libev, so better update to the
		5010	new API early than late.
4636		5011
4637	=over 4	5012	=over 4
4638		5013
4639	=item C<ev_loop_count> renamed to C<ev_iteration>	5014	=item C<EV_COMPAT3> backwards compatibility mechanism
4640		5015
4641	=item C<ev_loop_depth> renamed to C<ev_depth>	5016	The backward compatibility mechanism can be controlled by
		5017	C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING>
		5018	section.
4642		5019
4643	=item C<ev_loop_verify> renamed to C<ev_verify>	5020	=item C<ev_default_destroy> and C<ev_default_fork> have been removed
		5021
		5022	These calls can be replaced easily by their C<ev_loop_xxx> counterparts:
		5023
		5024	ev_loop_destroy (EV_DEFAULT_UC);
		5025	ev_loop_fork (EV_DEFAULT);
		5026
		5027	=item function/symbol renames
		5028
		5029	A number of functions and symbols have been renamed:
		5030
		5031	ev_loop => ev_run
		5032	EVLOOP_NONBLOCK => EVRUN_NOWAIT
		5033	EVLOOP_ONESHOT => EVRUN_ONCE
		5034
		5035	ev_unloop => ev_break
		5036	EVUNLOOP_CANCEL => EVBREAK_CANCEL
		5037	EVUNLOOP_ONE => EVBREAK_ONE
		5038	EVUNLOOP_ALL => EVBREAK_ALL
		5039
		5040	EV_TIMEOUT => EV_TIMER
		5041
		5042	ev_loop_count => ev_iteration
		5043	ev_loop_depth => ev_depth
		5044	ev_loop_verify => ev_verify
4644		5045
4645	Most functions working on C<struct ev_loop> objects don't have an	5046	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	5047	C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and
		5048	associated constants have been renamed to not collide with the C<struct
		5049	ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme
		5050	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	5051	C<ev_loop_fork> because it would otherwise clash with the C<ev_fork>
4648	C<ev_fork> typedef.	5052	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		5053
4659	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>	5054	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>
4660		5055
4661	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different	5056	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different
4662	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile	5057	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile
…		…
4669		5064
4670	=over 4	5065	=over 4
4671		5066
4672	=item active	5067	=item active
4673		5068
4674	A watcher is active as long as it has been started (has been attached to	5069	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).	5070	See L<WATCHER STATES> for details.
4676		5071
4677	=item application	5072	=item application
4678		5073
4679	In this document, an application is whatever is using libev.	5074	In this document, an application is whatever is using libev.
		5075
		5076	=item backend
		5077
		5078	The part of the code dealing with the operating system interfaces.
4680		5079
4681	=item callback	5080	=item callback
4682		5081
4683	The address of a function that is called when some event has been	5082	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	5083	detected. Callbacks are being passed the event loop, the watcher that
4685	received the event, and the actual event bitset.	5084	received the event, and the actual event bitset.
4686		5085
4687	=item callback invocation	5086	=item callback/watcher invocation
4688		5087
4689	The act of calling the callback associated with a watcher.	5088	The act of calling the callback associated with a watcher.
4690		5089
4691	=item event	5090	=item event
4692		5091
…		…
4711	The model used to describe how an event loop handles and processes	5110	The model used to describe how an event loop handles and processes
4712	watchers and events.	5111	watchers and events.
4713		5112
4714	=item pending	5113	=item pending
4715		5114
4716	A watcher is pending as soon as the corresponding event has been detected,	5115	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	5116	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		5117
4723	=item real time	5118	=item real time
4724		5119
4725	The physical time that is observed. It is apparently strictly monotonic :)	5120	The physical time that is observed. It is apparently strictly monotonic :)
4726		5121
…		…
4733	=item watcher	5128	=item watcher
4734		5129
4735	A data structure that describes interest in certain events. Watchers need	5130	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.	5131	to be started (attached to an event loop) before they can receive events.
4737		5132
4738	=item watcher invocation
4739
4740	The act of calling the callback associated with a watcher.
4741
4742	=back	5133	=back
4743		5134
4744	=head1 AUTHOR	5135	=head1 AUTHOR
4745		5136
4746	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson.	5137	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael
		5138	Magnusson and Emanuele Giaquinta.
4747		5139

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