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Revision 1.276 by root, Tue Dec 29 13:11:00 2009 UTC vs.
Revision 1.337 by root, Sun Oct 31 20:20:20 2010 UTC

…		…
26	puts ("stdin ready");	26	puts ("stdin ready");
27	// for one-shot events, one must manually stop the watcher	27	// for one-shot events, one must manually stop the watcher
28	// with its corresponding stop function.	28	// with its corresponding stop function.
29	ev_io_stop (EV_A_ w);	29	ev_io_stop (EV_A_ w);
30		30
31	// this causes all nested ev_loop's to stop iterating	31	// this causes all nested ev_run's to stop iterating
32	ev_unloop (EV_A_ EVUNLOOP_ALL);	32	ev_break (EV_A_ EVBREAK_ALL);
33	}	33	}
34		34
35	// another callback, this time for a time-out	35	// another callback, this time for a time-out
36	static void	36	static void
37	timeout_cb (EV_P_ ev_timer *w, int revents)	37	timeout_cb (EV_P_ ev_timer *w, int revents)
38	{	38	{
39	puts ("timeout");	39	puts ("timeout");
40	// this causes the innermost ev_loop to stop iterating	40	// this causes the innermost ev_run to stop iterating
41	ev_unloop (EV_A_ EVUNLOOP_ONE);	41	ev_break (EV_A_ EVBREAK_ONE);
42	}	42	}
43		43
44	int	44	int
45	main (void)	45	main (void)
46	{	46	{
47	// use the default event loop unless you have special needs	47	// use the default event loop unless you have special needs
48	struct ev_loop *loop = ev_default_loop (0);	48	struct ev_loop *loop = EV_DEFAULT;
49		49
50	// initialise an io watcher, then start it	50	// initialise an io watcher, then start it
51	// this one will watch for stdin to become readable	51	// this one will watch for stdin to become readable
52	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);	52	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);
53	ev_io_start (loop, &stdin_watcher);	53	ev_io_start (loop, &stdin_watcher);
…		…
56	// simple non-repeating 5.5 second timeout	56	// simple non-repeating 5.5 second timeout
57	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);	57	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
58	ev_timer_start (loop, &timeout_watcher);	58	ev_timer_start (loop, &timeout_watcher);
59		59
60	// now wait for events to arrive	60	// now wait for events to arrive
61	ev_loop (loop, 0);	61	ev_run (loop, 0);
62		62
63	// unloop was called, so exit	63	// unloop was called, so exit
64	return 0;	64	return 0;
65	}	65	}
66		66
…		…
75	While this document tries to be as complete as possible in documenting	75	While this document tries to be as complete as possible in documenting
76	libev, its usage and the rationale behind its design, it is not a tutorial	76	libev, its usage and the rationale behind its design, it is not a tutorial
77	on event-based programming, nor will it introduce event-based programming	77	on event-based programming, nor will it introduce event-based programming
78	with libev.	78	with libev.
79		79
80	Familarity with event based programming techniques in general is assumed	80	Familiarity with event based programming techniques in general is assumed
81	throughout this document.	81	throughout this document.
		82
		83	=head1 WHAT TO READ WHEN IN A HURRY
		84
		85	This manual tries to be very detailed, but unfortunately, this also makes
		86	it very long. If you just want to know the basics of libev, I suggest
		87	reading L<ANATOMY OF A WATCHER>, then the L<EXAMPLE PROGRAM> above and
		88	look up the missing functions in L<GLOBAL FUNCTIONS> and the C<ev_io> and
		89	C<ev_timer> sections in L<WATCHER TYPES>.
82		90
83	=head1 ABOUT LIBEV	91	=head1 ABOUT LIBEV
84		92
85	Libev is an event loop: you register interest in certain events (such as a	93	Libev is an event loop: you register interest in certain events (such as a
86	file descriptor being readable or a timeout occurring), and it will manage	94	file descriptor being readable or a timeout occurring), and it will manage
…		…
124	this argument.	132	this argument.
125		133
126	=head2 TIME REPRESENTATION	134	=head2 TIME REPRESENTATION
127		135
128	Libev represents time as a single floating point number, representing	136	Libev represents time as a single floating point number, representing
129	the (fractional) number of seconds since the (POSIX) epoch (somewhere	137	the (fractional) number of seconds since the (POSIX) epoch (in practice
130	near the beginning of 1970, details are complicated, don't ask). This	138	somewhere near the beginning of 1970, details are complicated, don't
131	type is called C<ev_tstamp>, which is what you should use too. It usually	139	ask). This type is called C<ev_tstamp>, which is what you should use
132	aliases to the C<double> type in C. When you need to do any calculations	140	too. It usually aliases to the C<double> type in C. When you need to do
133	on it, you should treat it as some floating point value. Unlike the name	141	any calculations on it, you should treat it as some floating point value.
		142
134	component C<stamp> might indicate, it is also used for time differences	143	Unlike the name component C<stamp> might indicate, it is also used for
135	throughout libev.	144	time differences (e.g. delays) throughout libev.
136		145
137	=head1 ERROR HANDLING	146	=head1 ERROR HANDLING
138		147
139	Libev knows three classes of errors: operating system errors, usage errors	148	Libev knows three classes of errors: operating system errors, usage errors
140	and internal errors (bugs).	149	and internal errors (bugs).
…		…
164		173
165	=item ev_tstamp ev_time ()	174	=item ev_tstamp ev_time ()
166		175
167	Returns the current time as libev would use it. Please note that the	176	Returns the current time as libev would use it. Please note that the
168	C<ev_now> function is usually faster and also often returns the timestamp	177	C<ev_now> function is usually faster and also often returns the timestamp
169	you actually want to know.	178	you actually want to know. Also interesting is the combination of
		179	C<ev_update_now> and C<ev_now>.
170		180
171	=item ev_sleep (ev_tstamp interval)	181	=item ev_sleep (ev_tstamp interval)
172		182
173	Sleep for the given interval: The current thread will be blocked until	183	Sleep for the given interval: The current thread will be blocked until
174	either it is interrupted or the given time interval has passed. Basically	184	either it is interrupted or the given time interval has passed. Basically
…		…
191	as this indicates an incompatible change. Minor versions are usually	201	as this indicates an incompatible change. Minor versions are usually
192	compatible to older versions, so a larger minor version alone is usually	202	compatible to older versions, so a larger minor version alone is usually
193	not a problem.	203	not a problem.
194		204
195	Example: Make sure we haven't accidentally been linked against the wrong	205	Example: Make sure we haven't accidentally been linked against the wrong
196	version.	206	version (note, however, that this will not detect other ABI mismatches,
		207	such as LFS or reentrancy).
197		208
198	assert (("libev version mismatch",	209	assert (("libev version mismatch",
199	ev_version_major () == EV_VERSION_MAJOR	210	ev_version_major () == EV_VERSION_MAJOR
200	&& ev_version_minor () >= EV_VERSION_MINOR));	211	&& ev_version_minor () >= EV_VERSION_MINOR));
201		212
…		…
212	assert (("sorry, no epoll, no sex",	223	assert (("sorry, no epoll, no sex",
213	ev_supported_backends () & EVBACKEND_EPOLL));	224	ev_supported_backends () & EVBACKEND_EPOLL));
214		225
215	=item unsigned int ev_recommended_backends ()	226	=item unsigned int ev_recommended_backends ()
216		227
217	Return the set of all backends compiled into this binary of libev and also	228	Return the set of all backends compiled into this binary of libev and
218	recommended for this platform. This set is often smaller than the one	229	also recommended for this platform, meaning it will work for most file
		230	descriptor types. This set is often smaller than the one returned by
219	returned by C<ev_supported_backends>, as for example kqueue is broken on	231	C<ev_supported_backends>, as for example kqueue is broken on most BSDs
220	most BSDs and will not be auto-detected unless you explicitly request it	232	and will not be auto-detected unless you explicitly request it (assuming
221	(assuming you know what you are doing). This is the set of backends that	233	you know what you are doing). This is the set of backends that libev will
222	libev will probe for if you specify no backends explicitly.	234	probe for if you specify no backends explicitly.
223		235
224	=item unsigned int ev_embeddable_backends ()	236	=item unsigned int ev_embeddable_backends ()
225		237
226	Returns the set of backends that are embeddable in other event loops. This	238	Returns the set of backends that are embeddable in other event loops. This
227	is the theoretical, all-platform, value. To find which backends	239	value is platform-specific but can include backends not available on the
228	might be supported on the current system, you would need to look at	240	current system. To find which embeddable backends might be supported on
229	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for	241	the current system, you would need to look at C<ev_embeddable_backends ()
230	recommended ones.	242	& ev_supported_backends ()>, likewise for recommended ones.
231		243
232	See the description of C<ev_embed> watchers for more info.	244	See the description of C<ev_embed> watchers for more info.
233		245
234	=item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT]	246	=item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT]
235		247
…		…
289	...	301	...
290	ev_set_syserr_cb (fatal_error);	302	ev_set_syserr_cb (fatal_error);
291		303
292	=back	304	=back
293		305
294	=head1 FUNCTIONS CONTROLLING THE EVENT LOOP	306	=head1 FUNCTIONS CONTROLLING EVENT LOOPS
295		307
296	An event loop is described by a C<struct ev_loop *> (the C<struct>	308	An event loop is described by a C<struct ev_loop *> (the C<struct> is
297	is I<not> optional in this case, as there is also an C<ev_loop>	309	I<not> optional in this case unless libev 3 compatibility is disabled, as
298	I<function>).	310	libev 3 had an C<ev_loop> function colliding with the struct name).
299		311
300	The library knows two types of such loops, the I<default> loop, which	312	The library knows two types of such loops, the I<default> loop, which
301	supports signals and child events, and dynamically created loops which do	313	supports child process events, and dynamically created event loops which
302	not.	314	do not.
303		315
304	=over 4	316	=over 4
305		317
306	=item struct ev_loop *ev_default_loop (unsigned int flags)	318	=item struct ev_loop *ev_default_loop (unsigned int flags)
307		319
308	This will initialise the default event loop if it hasn't been initialised	320	This returns the "default" event loop object, which is what you should
309	yet and return it. If the default loop could not be initialised, returns	321	normally use when you just need "the event loop". Event loop objects and
310	false. If it already was initialised it simply returns it (and ignores the	322	the C<flags> parameter are described in more detail in the entry for
311	flags. If that is troubling you, check C<ev_backend ()> afterwards).	323	C<ev_loop_new>.
		324
		325	If the default loop is already initialised then this function simply
		326	returns it (and ignores the flags. If that is troubling you, check
		327	C<ev_backend ()> afterwards). Otherwise it will create it with the given
		328	flags, which should almost always be C<0>, unless the caller is also the
		329	one calling C<ev_run> or otherwise qualifies as "the main program".
312		330
313	If you don't know what event loop to use, use the one returned from this	331	If you don't know what event loop to use, use the one returned from this
314	function.	332	function (or via the C<EV_DEFAULT> macro).
315		333
316	Note that this function is I<not> thread-safe, so if you want to use it	334	Note that this function is I<not> thread-safe, so if you want to use it
317	from multiple threads, you have to lock (note also that this is unlikely,	335	from multiple threads, you have to employ some kind of mutex (note also
318	as loops cannot be shared easily between threads anyway).	336	that this case is unlikely, as loops cannot be shared easily between
		337	threads anyway).
319		338
320	The default loop is the only loop that can handle C<ev_signal> and	339	The default loop is the only loop that can handle C<ev_child> watchers,
321	C<ev_child> watchers, and to do this, it always registers a handler	340	and to do this, it always registers a handler for C<SIGCHLD>. If this is
322	for C<SIGCHLD>. If this is a problem for your application you can either	341	a problem for your application you can either create a dynamic loop with
323	create a dynamic loop with C<ev_loop_new> that doesn't do that, or you	342	C<ev_loop_new> which doesn't do that, or you can simply overwrite the
324	can simply overwrite the C<SIGCHLD> signal handler I<after> calling	343	C<SIGCHLD> signal handler I<after> calling C<ev_default_init>.
325	C<ev_default_init>.	344
		345	Example: This is the most typical usage.
		346
		347	if (!ev_default_loop (0))
		348	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
		349
		350	Example: Restrict libev to the select and poll backends, and do not allow
		351	environment settings to be taken into account:
		352
		353	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
		354
		355	=item struct ev_loop *ev_loop_new (unsigned int flags)
		356
		357	This will create and initialise a new event loop object. If the loop
		358	could not be initialised, returns false.
		359
		360	Note that this function I<is> thread-safe, and one common way to use
		361	libev with threads is indeed to create one loop per thread, and using the
		362	default loop in the "main" or "initial" thread.
326		363
327	The flags argument can be used to specify special behaviour or specific	364	The flags argument can be used to specify special behaviour or specific
328	backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>).	365	backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>).
329		366
330	The following flags are supported:	367	The following flags are supported:
…		…
345	useful to try out specific backends to test their performance, or to work	382	useful to try out specific backends to test their performance, or to work
346	around bugs.	383	around bugs.
347		384
348	=item C<EVFLAG_FORKCHECK>	385	=item C<EVFLAG_FORKCHECK>
349		386
350	Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after	387	Instead of calling C<ev_loop_fork> manually after a fork, you can also
351	a fork, you can also make libev check for a fork in each iteration by	388	make libev check for a fork in each iteration by enabling this flag.
352	enabling this flag.
353		389
354	This works by calling C<getpid ()> on every iteration of the loop,	390	This works by calling C<getpid ()> on every iteration of the loop,
355	and thus this might slow down your event loop if you do a lot of loop	391	and thus this might slow down your event loop if you do a lot of loop
356	iterations and little real work, but is usually not noticeable (on my	392	iterations and little real work, but is usually not noticeable (on my
357	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence	393	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence
…		…
370	When this flag is specified, then libev will not attempt to use the	406	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	407	I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and
372	testing, this flag can be useful to conserve inotify file descriptors, as	408	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.	409	otherwise each loop using C<ev_stat> watchers consumes one inotify handle.
374		410
375	=item C<EVFLAG_NOSIGFD>	411	=item C<EVFLAG_SIGNALFD>
376		412
377	When this flag is specified, then libev will not attempt to use the	413	When this flag is specified, then libev will attempt to use the
378	I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This is	414	I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This API
379	probably only useful to work around any bugs in libev. Consequently, this	415	delivers signals synchronously, which makes it both faster and might make
380	flag might go away once the signalfd functionality is considered stable,	416	it possible to get the queued signal data. It can also simplify signal
381	so it's useful mostly in environment variables and not in program code.	417	handling with threads, as long as you properly block signals in your
		418	threads that are not interested in handling them.
		419
		420	Signalfd will not be used by default as this changes your signal mask, and
		421	there are a lot of shoddy libraries and programs (glib's threadpool for
		422	example) that can't properly initialise their signal masks.
382		423
383	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	424	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
384		425
385	This is your standard select(2) backend. Not I<completely> standard, as	426	This is your standard select(2) backend. Not I<completely> standard, as
386	libev tries to roll its own fd_set with no limits on the number of fds,	427	libev tries to roll its own fd_set with no limits on the number of fds,
…		…
422	epoll scales either O(1) or O(active_fds).	463	epoll scales either O(1) or O(active_fds).
423		464
424	The epoll mechanism deserves honorable mention as the most misdesigned	465	The epoll mechanism deserves honorable mention as the most misdesigned
425	of the more advanced event mechanisms: mere annoyances include silently	466	of the more advanced event mechanisms: mere annoyances include silently
426	dropping file descriptors, requiring a system call per change per file	467	dropping file descriptors, requiring a system call per change per file
427	descriptor (and unnecessary guessing of parameters), problems with dup and	468	descriptor (and unnecessary guessing of parameters), problems with dup,
		469	returning before the timeout value requiring additional iterations and so
428	so on. The biggest issue is fork races, however - if a program forks then	470	on. The biggest issue is fork races, however - if a program forks then
429	I<both> parent and child process have to recreate the epoll set, which can	471	I<both> parent and child process have to recreate the epoll set, which can
430	take considerable time (one syscall per file descriptor) and is of course	472	take considerable time (one syscall per file descriptor) and is of course
431	hard to detect.	473	hard to detect.
432		474
433	Epoll is also notoriously buggy - embedding epoll fds I<should> work, but	475	Epoll is also notoriously buggy - embedding epoll fds I<should> work, but
434	of course I<doesn't>, and epoll just loves to report events for totally	476	of course I<doesn't>, and epoll just loves to report events for totally
435	I<different> file descriptors (even already closed ones, so one cannot	477	I<different> file descriptors (even already closed ones, so one cannot
436	even remove them from the set) than registered in the set (especially	478	even remove them from the set) than registered in the set (especially
437	on SMP systems). Libev tries to counter these spurious notifications by	479	on SMP systems). Libev tries to counter these spurious notifications by
438	employing an additional generation counter and comparing that against the	480	employing an additional generation counter and comparing that against the
439	events to filter out spurious ones, recreating the set when required.	481	events to filter out spurious ones, recreating the set when required. Last
		482	not least, it also refuses to work with some file descriptors which work
		483	perfectly fine with C<select> (files, many character devices...).
440		484
441	While stopping, setting and starting an I/O watcher in the same iteration	485	While stopping, setting and starting an I/O watcher in the same iteration
442	will result in some caching, there is still a system call per such	486	will result in some caching, there is still a system call per such
443	incident (because the same I<file descriptor> could point to a different	487	incident (because the same I<file descriptor> could point to a different
444	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed	488	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed
…		…
542	If one or more of the backend flags are or'ed into the flags value,	586	If one or more of the backend flags are or'ed into the flags value,
543	then only these backends will be tried (in the reverse order as listed	587	then only these backends will be tried (in the reverse order as listed
544	here). If none are specified, all backends in C<ev_recommended_backends	588	here). If none are specified, all backends in C<ev_recommended_backends
545	()> will be tried.	589	()> will be tried.
546		590
547	Example: This is the most typical usage.
548
549	if (!ev_default_loop (0))
550	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
551
552	Example: Restrict libev to the select and poll backends, and do not allow
553	environment settings to be taken into account:
554
555	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
556
557	Example: Use whatever libev has to offer, but make sure that kqueue is
558	used if available (warning, breaks stuff, best use only with your own
559	private event loop and only if you know the OS supports your types of
560	fds):
561
562	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
563
564	=item struct ev_loop *ev_loop_new (unsigned int flags)
565
566	Similar to C<ev_default_loop>, but always creates a new event loop that is
567	always distinct from the default loop. Unlike the default loop, it cannot
568	handle signal and child watchers, and attempts to do so will be greeted by
569	undefined behaviour (or a failed assertion if assertions are enabled).
570
571	Note that this function I<is> thread-safe, and the recommended way to use
572	libev with threads is indeed to create one loop per thread, and using the
573	default loop in the "main" or "initial" thread.
574
575	Example: Try to create a event loop that uses epoll and nothing else.	591	Example: Try to create a event loop that uses epoll and nothing else.
576		592
577	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	593	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
578	if (!epoller)	594	if (!epoller)
579	fatal ("no epoll found here, maybe it hides under your chair");	595	fatal ("no epoll found here, maybe it hides under your chair");
580		596
		597	Example: Use whatever libev has to offer, but make sure that kqueue is
		598	used if available.
		599
		600	struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE);
		601
581	=item ev_default_destroy ()	602	=item ev_loop_destroy (loop)
582		603
583	Destroys the default loop again (frees all memory and kernel state	604	Destroys an event loop object (frees all memory and kernel state
584	etc.). None of the active event watchers will be stopped in the normal	605	etc.). None of the active event watchers will be stopped in the normal
585	sense, so e.g. C<ev_is_active> might still return true. It is your	606	sense, so e.g. C<ev_is_active> might still return true. It is your
586	responsibility to either stop all watchers cleanly yourself I<before>	607	responsibility to either stop all watchers cleanly yourself I<before>
587	calling this function, or cope with the fact afterwards (which is usually	608	calling this function, or cope with the fact afterwards (which is usually
588	the easiest thing, you can just ignore the watchers and/or C<free ()> them	609	the easiest thing, you can just ignore the watchers and/or C<free ()> them
…		…
590		611
591	Note that certain global state, such as signal state (and installed signal	612	Note that certain global state, such as signal state (and installed signal
592	handlers), will not be freed by this function, and related watchers (such	613	handlers), will not be freed by this function, and related watchers (such
593	as signal and child watchers) would need to be stopped manually.	614	as signal and child watchers) would need to be stopped manually.
594		615
595	In general it is not advisable to call this function except in the	616	This function is normally used on loop objects allocated by
596	rare occasion where you really need to free e.g. the signal handling	617	C<ev_loop_new>, but it can also be used on the default loop returned by
		618	C<ev_default_loop>, in which case it is not thread-safe.
		619
		620	Note that it is not advisable to call this function on the default loop
		621	except in the rare occasion where you really need to free it's resources.
597	pipe fds. If you need dynamically allocated loops it is better to use	622	If you need dynamically allocated loops it is better to use C<ev_loop_new>
598	C<ev_loop_new> and C<ev_loop_destroy>.	623	and C<ev_loop_destroy>.
599		624
600	=item ev_loop_destroy (loop)	625	=item ev_loop_fork (loop)
601		626
602	Like C<ev_default_destroy>, but destroys an event loop created by an
603	earlier call to C<ev_loop_new>.
604
605	=item ev_default_fork ()
606
607	This function sets a flag that causes subsequent C<ev_loop> iterations	627	This function sets a flag that causes subsequent C<ev_run> iterations to
608	to reinitialise the kernel state for backends that have one. Despite the	628	reinitialise the kernel state for backends that have one. Despite the
609	name, you can call it anytime, but it makes most sense after forking, in	629	name, you can call it anytime, but it makes most sense after forking, in
610	the child process (or both child and parent, but that again makes little	630	the child process. You I<must> call it (or use C<EVFLAG_FORKCHECK>) in the
611	sense). You I<must> call it in the child before using any of the libev	631	child before resuming or calling C<ev_run>.
612	functions, and it will only take effect at the next C<ev_loop> iteration.	632
		633	Again, you I<have> to call it on I<any> loop that you want to re-use after
		634	a fork, I<even if you do not plan to use the loop in the parent>. This is
		635	because some kernel interfaces *cough* I<kqueue> *cough* do funny things
		636	during fork.
613		637
614	On the other hand, you only need to call this function in the child	638	On the other hand, you only need to call this function in the child
615	process if and only if you want to use the event library in the child. If	639	process if and only if you want to use the event loop in the child. If
616	you just fork+exec, you don't have to call it at all.	640	you just fork+exec or create a new loop in the child, you don't have to
		641	call it at all (in fact, C<epoll> is so badly broken that it makes a
		642	difference, but libev will usually detect this case on its own and do a
		643	costly reset of the backend).
617		644
618	The function itself is quite fast and it's usually not a problem to call	645	The function itself is quite fast and it's usually not a problem to call
619	it just in case after a fork. To make this easy, the function will fit in	646	it just in case after a fork.
620	quite nicely into a call to C<pthread_atfork>:
621		647
		648	Example: Automate calling C<ev_loop_fork> on the default loop when
		649	using pthreads.
		650
		651	static void
		652	post_fork_child (void)
		653	{
		654	ev_loop_fork (EV_DEFAULT);
		655	}
		656
		657	...
622	pthread_atfork (0, 0, ev_default_fork);	658	pthread_atfork (0, 0, post_fork_child);
623
624	=item ev_loop_fork (loop)
625
626	Like C<ev_default_fork>, but acts on an event loop created by
627	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
628	after fork that you want to re-use in the child, and how you do this is
629	entirely your own problem.
630		659
631	=item int ev_is_default_loop (loop)	660	=item int ev_is_default_loop (loop)
632		661
633	Returns true when the given loop is, in fact, the default loop, and false	662	Returns true when the given loop is, in fact, the default loop, and false
634	otherwise.	663	otherwise.
635		664
636	=item unsigned int ev_loop_count (loop)	665	=item unsigned int ev_iteration (loop)
637		666
638	Returns the count of loop iterations for the loop, which is identical to	667	Returns the current iteration count for the event loop, which is identical
639	the number of times libev did poll for new events. It starts at C<0> and	668	to the number of times libev did poll for new events. It starts at C<0>
640	happily wraps around with enough iterations.	669	and happily wraps around with enough iterations.
641		670
642	This value can sometimes be useful as a generation counter of sorts (it	671	This value can sometimes be useful as a generation counter of sorts (it
643	"ticks" the number of loop iterations), as it roughly corresponds with	672	"ticks" the number of loop iterations), as it roughly corresponds with
644	C<ev_prepare> and C<ev_check> calls.	673	C<ev_prepare> and C<ev_check> calls - and is incremented between the
		674	prepare and check phases.
645		675
646	=item unsigned int ev_loop_depth (loop)	676	=item unsigned int ev_depth (loop)
647		677
648	Returns the number of times C<ev_loop> was entered minus the number of	678	Returns the number of times C<ev_run> was entered minus the number of
649	times C<ev_loop> was exited, in other words, the recursion depth.	679	times C<ev_run> was exited, in other words, the recursion depth.
650		680
651	Outside C<ev_loop>, this number is zero. In a callback, this number is	681	Outside C<ev_run>, this number is zero. In a callback, this number is
652	C<1>, unless C<ev_loop> was invoked recursively (or from another thread),	682	C<1>, unless C<ev_run> was invoked recursively (or from another thread),
653	in which case it is higher.	683	in which case it is higher.
654		684
655	Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread	685	Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread
656	etc.), doesn't count as exit.	686	etc.), doesn't count as "exit" - consider this as a hint to avoid such
		687	ungentleman-like behaviour unless it's really convenient.
657		688
658	=item unsigned int ev_backend (loop)	689	=item unsigned int ev_backend (loop)
659		690
660	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	691	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
661	use.	692	use.
…		…
670		701
671	=item ev_now_update (loop)	702	=item ev_now_update (loop)
672		703
673	Establishes the current time by querying the kernel, updating the time	704	Establishes the current time by querying the kernel, updating the time
674	returned by C<ev_now ()> in the progress. This is a costly operation and	705	returned by C<ev_now ()> in the progress. This is a costly operation and
675	is usually done automatically within C<ev_loop ()>.	706	is usually done automatically within C<ev_run ()>.
676		707
677	This function is rarely useful, but when some event callback runs for a	708	This function is rarely useful, but when some event callback runs for a
678	very long time without entering the event loop, updating libev's idea of	709	very long time without entering the event loop, updating libev's idea of
679	the current time is a good idea.	710	the current time is a good idea.
680		711
…		…
682		713
683	=item ev_suspend (loop)	714	=item ev_suspend (loop)
684		715
685	=item ev_resume (loop)	716	=item ev_resume (loop)
686		717
687	These two functions suspend and resume a loop, for use when the loop is	718	These two functions suspend and resume an event loop, for use when the
688	not used for a while and timeouts should not be processed.	719	loop is not used for a while and timeouts should not be processed.
689		720
690	A typical use case would be an interactive program such as a game: When	721	A typical use case would be an interactive program such as a game: When
691	the user presses C<^Z> to suspend the game and resumes it an hour later it	722	the user presses C<^Z> to suspend the game and resumes it an hour later it
692	would be best to handle timeouts as if no time had actually passed while	723	would be best to handle timeouts as if no time had actually passed while
693	the program was suspended. This can be achieved by calling C<ev_suspend>	724	the program was suspended. This can be achieved by calling C<ev_suspend>
…		…
695	C<ev_resume> directly afterwards to resume timer processing.	726	C<ev_resume> directly afterwards to resume timer processing.
696		727
697	Effectively, all C<ev_timer> watchers will be delayed by the time spend	728	Effectively, all C<ev_timer> watchers will be delayed by the time spend
698	between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers	729	between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers
699	will be rescheduled (that is, they will lose any events that would have	730	will be rescheduled (that is, they will lose any events that would have
700	occured while suspended).	731	occurred while suspended).
701		732
702	After calling C<ev_suspend> you B<must not> call I<any> function on the	733	After calling C<ev_suspend> you B<must not> call I<any> function on the
703	given loop other than C<ev_resume>, and you B<must not> call C<ev_resume>	734	given loop other than C<ev_resume>, and you B<must not> call C<ev_resume>
704	without a previous call to C<ev_suspend>.	735	without a previous call to C<ev_suspend>.
705		736
706	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the	737	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the
707	event loop time (see C<ev_now_update>).	738	event loop time (see C<ev_now_update>).
708		739
709	=item ev_loop (loop, int flags)	740	=item ev_run (loop, int flags)
710		741
711	Finally, this is it, the event handler. This function usually is called	742	Finally, this is it, the event handler. This function usually is called
712	after you have initialised all your watchers and you want to start	743	after you have initialised all your watchers and you want to start
713	handling events.	744	handling events. It will ask the operating system for any new events, call
		745	the watcher callbacks, an then repeat the whole process indefinitely: This
		746	is why event loops are called I<loops>.
714		747
715	If the flags argument is specified as C<0>, it will not return until	748	If the flags argument is specified as C<0>, it will keep handling events
716	either no event watchers are active anymore or C<ev_unloop> was called.	749	until either no event watchers are active anymore or C<ev_break> was
		750	called.
717		751
718	Please note that an explicit C<ev_unloop> is usually better than	752	Please note that an explicit C<ev_break> is usually better than
719	relying on all watchers to be stopped when deciding when a program has	753	relying on all watchers to be stopped when deciding when a program has
720	finished (especially in interactive programs), but having a program	754	finished (especially in interactive programs), but having a program
721	that automatically loops as long as it has to and no longer by virtue	755	that automatically loops as long as it has to and no longer by virtue
722	of relying on its watchers stopping correctly, that is truly a thing of	756	of relying on its watchers stopping correctly, that is truly a thing of
723	beauty.	757	beauty.
724		758
725	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle	759	A flags value of C<EVRUN_NOWAIT> will look for new events, will handle
726	those events and any already outstanding ones, but will not block your	760	those events and any already outstanding ones, but will not wait and
727	process in case there are no events and will return after one iteration of	761	block your process in case there are no events and will return after one
728	the loop.	762	iteration of the loop. This is sometimes useful to poll and handle new
		763	events while doing lengthy calculations, to keep the program responsive.
729		764
730	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if	765	A flags value of C<EVRUN_ONCE> will look for new events (waiting if
731	necessary) and will handle those and any already outstanding ones. It	766	necessary) and will handle those and any already outstanding ones. It
732	will block your process until at least one new event arrives (which could	767	will block your process until at least one new event arrives (which could
733	be an event internal to libev itself, so there is no guarantee that a	768	be an event internal to libev itself, so there is no guarantee that a
734	user-registered callback will be called), and will return after one	769	user-registered callback will be called), and will return after one
735	iteration of the loop.	770	iteration of the loop.
736		771
737	This is useful if you are waiting for some external event in conjunction	772	This is useful if you are waiting for some external event in conjunction
738	with something not expressible using other libev watchers (i.e. "roll your	773	with something not expressible using other libev watchers (i.e. "roll your
739	own C<ev_loop>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is	774	own C<ev_run>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is
740	usually a better approach for this kind of thing.	775	usually a better approach for this kind of thing.
741		776
742	Here are the gory details of what C<ev_loop> does:	777	Here are the gory details of what C<ev_run> does:
743		778
		779	- Increment loop depth.
		780	- Reset the ev_break status.
744	- Before the first iteration, call any pending watchers.	781	- Before the first iteration, call any pending watchers.
		782	LOOP:
745	* If EVFLAG_FORKCHECK was used, check for a fork.	783	- If EVFLAG_FORKCHECK was used, check for a fork.
746	- If a fork was detected (by any means), queue and call all fork watchers.	784	- If a fork was detected (by any means), queue and call all fork watchers.
747	- Queue and call all prepare watchers.	785	- Queue and call all prepare watchers.
		786	- If ev_break was called, goto FINISH.
748	- If we have been forked, detach and recreate the kernel state	787	- If we have been forked, detach and recreate the kernel state
749	as to not disturb the other process.	788	as to not disturb the other process.
750	- Update the kernel state with all outstanding changes.	789	- Update the kernel state with all outstanding changes.
751	- Update the "event loop time" (ev_now ()).	790	- Update the "event loop time" (ev_now ()).
752	- Calculate for how long to sleep or block, if at all	791	- Calculate for how long to sleep or block, if at all
753	(active idle watchers, EVLOOP_NONBLOCK or not having	792	(active idle watchers, EVRUN_NOWAIT or not having
754	any active watchers at all will result in not sleeping).	793	any active watchers at all will result in not sleeping).
755	- Sleep if the I/O and timer collect interval say so.	794	- Sleep if the I/O and timer collect interval say so.
		795	- Increment loop iteration counter.
756	- Block the process, waiting for any events.	796	- Block the process, waiting for any events.
757	- Queue all outstanding I/O (fd) events.	797	- Queue all outstanding I/O (fd) events.
758	- Update the "event loop time" (ev_now ()), and do time jump adjustments.	798	- Update the "event loop time" (ev_now ()), and do time jump adjustments.
759	- Queue all expired timers.	799	- Queue all expired timers.
760	- Queue all expired periodics.	800	- Queue all expired periodics.
761	- Unless any events are pending now, queue all idle watchers.	801	- Queue all idle watchers with priority higher than that of pending events.
762	- Queue all check watchers.	802	- Queue all check watchers.
763	- Call all queued watchers in reverse order (i.e. check watchers first).	803	- Call all queued watchers in reverse order (i.e. check watchers first).
764	Signals and child watchers are implemented as I/O watchers, and will	804	Signals and child watchers are implemented as I/O watchers, and will
765	be handled here by queueing them when their watcher gets executed.	805	be handled here by queueing them when their watcher gets executed.
766	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	806	- If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT
767	were used, or there are no active watchers, return, otherwise	807	were used, or there are no active watchers, goto FINISH, otherwise
768	continue with step *.	808	continue with step LOOP.
		809	FINISH:
		810	- Reset the ev_break status iff it was EVBREAK_ONE.
		811	- Decrement the loop depth.
		812	- Return.
769		813
770	Example: Queue some jobs and then loop until no events are outstanding	814	Example: Queue some jobs and then loop until no events are outstanding
771	anymore.	815	anymore.
772		816
773	... queue jobs here, make sure they register event watchers as long	817	... queue jobs here, make sure they register event watchers as long
774	... as they still have work to do (even an idle watcher will do..)	818	... as they still have work to do (even an idle watcher will do..)
775	ev_loop (my_loop, 0);	819	ev_run (my_loop, 0);
776	... jobs done or somebody called unloop. yeah!	820	... jobs done or somebody called unloop. yeah!
777		821
778	=item ev_unloop (loop, how)	822	=item ev_break (loop, how)
779		823
780	Can be used to make a call to C<ev_loop> return early (but only after it	824	Can be used to make a call to C<ev_run> return early (but only after it
781	has processed all outstanding events). The C<how> argument must be either	825	has processed all outstanding events). The C<how> argument must be either
782	C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or	826	C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or
783	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.	827	C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return.
784		828
785	This "unloop state" will be cleared when entering C<ev_loop> again.	829	This "break state" will be cleared when entering C<ev_run> again.
786		830
787	It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls.	831	It is safe to call C<ev_break> from outside any C<ev_run> calls, too.
788		832
789	=item ev_ref (loop)	833	=item ev_ref (loop)
790		834
791	=item ev_unref (loop)	835	=item ev_unref (loop)
792		836
793	Ref/unref can be used to add or remove a reference count on the event	837	Ref/unref can be used to add or remove a reference count on the event
794	loop: Every watcher keeps one reference, and as long as the reference	838	loop: Every watcher keeps one reference, and as long as the reference
795	count is nonzero, C<ev_loop> will not return on its own.	839	count is nonzero, C<ev_run> will not return on its own.
796		840
797	This is useful when you have a watcher that you never intend to	841	This is useful when you have a watcher that you never intend to
798	unregister, but that nevertheless should not keep C<ev_loop> from	842	unregister, but that nevertheless should not keep C<ev_run> from
799	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>	843	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>
800	before stopping it.	844	before stopping it.
801		845
802	As an example, libev itself uses this for its internal signal pipe: It	846	As an example, libev itself uses this for its internal signal pipe: It
803	is not visible to the libev user and should not keep C<ev_loop> from	847	is not visible to the libev user and should not keep C<ev_run> from
804	exiting if no event watchers registered by it are active. It is also an	848	exiting if no event watchers registered by it are active. It is also an
805	excellent way to do this for generic recurring timers or from within	849	excellent way to do this for generic recurring timers or from within
806	third-party libraries. Just remember to I<unref after start> and I<ref	850	third-party libraries. Just remember to I<unref after start> and I<ref
807	before stop> (but only if the watcher wasn't active before, or was active	851	before stop> (but only if the watcher wasn't active before, or was active
808	before, respectively. Note also that libev might stop watchers itself	852	before, respectively. Note also that libev might stop watchers itself
809	(e.g. non-repeating timers) in which case you have to C<ev_ref>	853	(e.g. non-repeating timers) in which case you have to C<ev_ref>
810	in the callback).	854	in the callback).
811		855
812	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	856	Example: Create a signal watcher, but keep it from keeping C<ev_run>
813	running when nothing else is active.	857	running when nothing else is active.
814		858
815	ev_signal exitsig;	859	ev_signal exitsig;
816	ev_signal_init (&exitsig, sig_cb, SIGINT);	860	ev_signal_init (&exitsig, sig_cb, SIGINT);
817	ev_signal_start (loop, &exitsig);	861	ev_signal_start (loop, &exitsig);
…		…
862	usually doesn't make much sense to set it to a lower value than C<0.01>,	906	usually doesn't make much sense to set it to a lower value than C<0.01>,
863	as this approaches the timing granularity of most systems. Note that if	907	as this approaches the timing granularity of most systems. Note that if
864	you do transactions with the outside world and you can't increase the	908	you do transactions with the outside world and you can't increase the
865	parallelity, then this setting will limit your transaction rate (if you	909	parallelity, then this setting will limit your transaction rate (if you
866	need to poll once per transaction and the I/O collect interval is 0.01,	910	need to poll once per transaction and the I/O collect interval is 0.01,
867	then you can't do more than 100 transations per second).	911	then you can't do more than 100 transactions per second).
868		912
869	Setting the I<timeout collect interval> can improve the opportunity for	913	Setting the I<timeout collect interval> can improve the opportunity for
870	saving power, as the program will "bundle" timer callback invocations that	914	saving power, as the program will "bundle" timer callback invocations that
871	are "near" in time together, by delaying some, thus reducing the number of	915	are "near" in time together, by delaying some, thus reducing the number of
872	times the process sleeps and wakes up again. Another useful technique to	916	times the process sleeps and wakes up again. Another useful technique to
…		…
880	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);	924	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);
881		925
882	=item ev_invoke_pending (loop)	926	=item ev_invoke_pending (loop)
883		927
884	This call will simply invoke all pending watchers while resetting their	928	This call will simply invoke all pending watchers while resetting their
885	pending state. Normally, C<ev_loop> does this automatically when required,	929	pending state. Normally, C<ev_run> does this automatically when required,
886	but when overriding the invoke callback this call comes handy.	930	but when overriding the invoke callback this call comes handy. This
		931	function can be invoked from a watcher - this can be useful for example
		932	when you want to do some lengthy calculation and want to pass further
		933	event handling to another thread (you still have to make sure only one
		934	thread executes within C<ev_invoke_pending> or C<ev_run> of course).
887		935
888	=item int ev_pending_count (loop)	936	=item int ev_pending_count (loop)
889		937
890	Returns the number of pending watchers - zero indicates that no watchers	938	Returns the number of pending watchers - zero indicates that no watchers
891	are pending.	939	are pending.
892		940
893	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))	941	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))
894		942
895	This overrides the invoke pending functionality of the loop: Instead of	943	This overrides the invoke pending functionality of the loop: Instead of
896	invoking all pending watchers when there are any, C<ev_loop> will call	944	invoking all pending watchers when there are any, C<ev_run> will call
897	this callback instead. This is useful, for example, when you want to	945	this callback instead. This is useful, for example, when you want to
898	invoke the actual watchers inside another context (another thread etc.).	946	invoke the actual watchers inside another context (another thread etc.).
899		947
900	If you want to reset the callback, use C<ev_invoke_pending> as new	948	If you want to reset the callback, use C<ev_invoke_pending> as new
901	callback.	949	callback.
…		…
904		952
905	Sometimes you want to share the same loop between multiple threads. This	953	Sometimes you want to share the same loop between multiple threads. This
906	can be done relatively simply by putting mutex_lock/unlock calls around	954	can be done relatively simply by putting mutex_lock/unlock calls around
907	each call to a libev function.	955	each call to a libev function.
908		956
909	However, C<ev_loop> can run an indefinite time, so it is not feasible to	957	However, C<ev_run> can run an indefinite time, so it is not feasible
910	wait for it to return. One way around this is to wake up the loop via	958	to wait for it to return. One way around this is to wake up the event
911	C<ev_unloop> and C<av_async_send>, another way is to set these I<release>	959	loop via C<ev_break> and C<av_async_send>, another way is to set these
912	and I<acquire> callbacks on the loop.	960	I<release> and I<acquire> callbacks on the loop.
913		961
914	When set, then C<release> will be called just before the thread is	962	When set, then C<release> will be called just before the thread is
915	suspended waiting for new events, and C<acquire> is called just	963	suspended waiting for new events, and C<acquire> is called just
916	afterwards.	964	afterwards.
917		965
…		…
920		968
921	While event loop modifications are allowed between invocations of	969	While event loop modifications are allowed between invocations of
922	C<release> and C<acquire> (that's their only purpose after all), no	970	C<release> and C<acquire> (that's their only purpose after all), no
923	modifications done will affect the event loop, i.e. adding watchers will	971	modifications done will affect the event loop, i.e. adding watchers will
924	have no effect on the set of file descriptors being watched, or the time	972	have no effect on the set of file descriptors being watched, or the time
925	waited. Use an C<ev_async> watcher to wake up C<ev_loop> when you want it	973	waited. Use an C<ev_async> watcher to wake up C<ev_run> when you want it
926	to take note of any changes you made.	974	to take note of any changes you made.
927		975
928	In theory, threads executing C<ev_loop> will be async-cancel safe between	976	In theory, threads executing C<ev_run> will be async-cancel safe between
929	invocations of C<release> and C<acquire>.	977	invocations of C<release> and C<acquire>.
930		978
931	See also the locking example in the C<THREADS> section later in this	979	See also the locking example in the C<THREADS> section later in this
932	document.	980	document.
933		981
…		…
942	These two functions can be used to associate arbitrary data with a loop,	990	These two functions can be used to associate arbitrary data with a loop,
943	and are intended solely for the C<invoke_pending_cb>, C<release> and	991	and are intended solely for the C<invoke_pending_cb>, C<release> and
944	C<acquire> callbacks described above, but of course can be (ab-)used for	992	C<acquire> callbacks described above, but of course can be (ab-)used for
945	any other purpose as well.	993	any other purpose as well.
946		994
947	=item ev_loop_verify (loop)	995	=item ev_verify (loop)
948		996
949	This function only does something when C<EV_VERIFY> support has been	997	This function only does something when C<EV_VERIFY> support has been
950	compiled in, which is the default for non-minimal builds. It tries to go	998	compiled in, which is the default for non-minimal builds. It tries to go
951	through all internal structures and checks them for validity. If anything	999	through all internal structures and checks them for validity. If anything
952	is found to be inconsistent, it will print an error message to standard	1000	is found to be inconsistent, it will print an error message to standard
…		…
963		1011
964	In the following description, uppercase C<TYPE> in names stands for the	1012	In the following description, uppercase C<TYPE> in names stands for the
965	watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer	1013	watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer
966	watchers and C<ev_io_start> for I/O watchers.	1014	watchers and C<ev_io_start> for I/O watchers.
967		1015
968	A watcher is a structure that you create and register to record your	1016	A watcher is an opaque structure that you allocate and register to record
969	interest in some event. For instance, if you want to wait for STDIN to	1017	your interest in some event. To make a concrete example, imagine you want
970	become readable, you would create an C<ev_io> watcher for that:	1018	to wait for STDIN to become readable, you would create an C<ev_io> watcher
		1019	for that:
971		1020
972	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)	1021	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)
973	{	1022	{
974	ev_io_stop (w);	1023	ev_io_stop (w);
975	ev_unloop (loop, EVUNLOOP_ALL);	1024	ev_break (loop, EVBREAK_ALL);
976	}	1025	}
977		1026
978	struct ev_loop *loop = ev_default_loop (0);	1027	struct ev_loop *loop = ev_default_loop (0);
979		1028
980	ev_io stdin_watcher;	1029	ev_io stdin_watcher;
981		1030
982	ev_init (&stdin_watcher, my_cb);	1031	ev_init (&stdin_watcher, my_cb);
983	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	1032	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
984	ev_io_start (loop, &stdin_watcher);	1033	ev_io_start (loop, &stdin_watcher);
985		1034
986	ev_loop (loop, 0);	1035	ev_run (loop, 0);
987		1036
988	As you can see, you are responsible for allocating the memory for your	1037	As you can see, you are responsible for allocating the memory for your
989	watcher structures (and it is I<usually> a bad idea to do this on the	1038	watcher structures (and it is I<usually> a bad idea to do this on the
990	stack).	1039	stack).
991		1040
992	Each watcher has an associated watcher structure (called C<struct ev_TYPE>	1041	Each watcher has an associated watcher structure (called C<struct ev_TYPE>
993	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).	1042	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).
994		1043
995	Each watcher structure must be initialised by a call to C<ev_init	1044	Each watcher structure must be initialised by a call to C<ev_init (watcher
996	(watcher *, callback)>, which expects a callback to be provided. This	1045	*, callback)>, which expects a callback to be provided. This callback is
997	callback gets invoked each time the event occurs (or, in the case of I/O	1046	invoked each time the event occurs (or, in the case of I/O watchers, each
998	watchers, each time the event loop detects that the file descriptor given	1047	time the event loop detects that the file descriptor given is readable
999	is readable and/or writable).	1048	and/or writable).
1000		1049
1001	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>	1050	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>
1002	macro to configure it, with arguments specific to the watcher type. There	1051	macro to configure it, with arguments specific to the watcher type. There
1003	is also a macro to combine initialisation and setting in one call: C<<	1052	is also a macro to combine initialisation and setting in one call: C<<
1004	ev_TYPE_init (watcher *, callback, ...) >>.	1053	ev_TYPE_init (watcher *, callback, ...) >>.
…		…
1027	=item C<EV_WRITE>	1076	=item C<EV_WRITE>
1028		1077
1029	The file descriptor in the C<ev_io> watcher has become readable and/or	1078	The file descriptor in the C<ev_io> watcher has become readable and/or
1030	writable.	1079	writable.
1031		1080
1032	=item C<EV_TIMEOUT>	1081	=item C<EV_TIMER>
1033		1082
1034	The C<ev_timer> watcher has timed out.	1083	The C<ev_timer> watcher has timed out.
1035		1084
1036	=item C<EV_PERIODIC>	1085	=item C<EV_PERIODIC>
1037		1086
…		…
1055		1104
1056	=item C<EV_PREPARE>	1105	=item C<EV_PREPARE>
1057		1106
1058	=item C<EV_CHECK>	1107	=item C<EV_CHECK>
1059		1108
1060	All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts	1109	All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts
1061	to gather new events, and all C<ev_check> watchers are invoked just after	1110	to gather new events, and all C<ev_check> watchers are invoked just after
1062	C<ev_loop> has gathered them, but before it invokes any callbacks for any	1111	C<ev_run> has gathered them, but before it invokes any callbacks for any
1063	received events. Callbacks of both watcher types can start and stop as	1112	received events. Callbacks of both watcher types can start and stop as
1064	many watchers as they want, and all of them will be taken into account	1113	many watchers as they want, and all of them will be taken into account
1065	(for example, a C<ev_prepare> watcher might start an idle watcher to keep	1114	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
1066	C<ev_loop> from blocking).	1115	C<ev_run> from blocking).
1067		1116
1068	=item C<EV_EMBED>	1117	=item C<EV_EMBED>
1069		1118
1070	The embedded event loop specified in the C<ev_embed> watcher needs attention.	1119	The embedded event loop specified in the C<ev_embed> watcher needs attention.
1071		1120
1072	=item C<EV_FORK>	1121	=item C<EV_FORK>
1073		1122
1074	The event loop has been resumed in the child process after fork (see	1123	The event loop has been resumed in the child process after fork (see
1075	C<ev_fork>).	1124	C<ev_fork>).
		1125
		1126	=item C<EV_CLEANUP>
		1127
		1128	The event loop is about to be destroyed (see C<ev_cleanup>).
1076		1129
1077	=item C<EV_ASYNC>	1130	=item C<EV_ASYNC>
1078		1131
1079	The given async watcher has been asynchronously notified (see C<ev_async>).	1132	The given async watcher has been asynchronously notified (see C<ev_async>).
1080		1133
…		…
1252		1305
1253	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related	1306	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related
1254	functions that do not need a watcher.	1307	functions that do not need a watcher.
1255		1308
1256	=back	1309	=back
1257
1258		1310
1259	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	1311	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
1260		1312
1261	Each watcher has, by default, a member C<void *data> that you can change	1313	Each watcher has, by default, a member C<void *data> that you can change
1262	and read at any time: libev will completely ignore it. This can be used	1314	and read at any time: libev will completely ignore it. This can be used
…		…
1318	t2_cb (EV_P_ ev_timer *w, int revents)	1370	t2_cb (EV_P_ ev_timer *w, int revents)
1319	{	1371	{
1320	struct my_biggy big = (struct my_biggy *)	1372	struct my_biggy big = (struct my_biggy *)
1321	(((char *)w) - offsetof (struct my_biggy, t2));	1373	(((char *)w) - offsetof (struct my_biggy, t2));
1322	}	1374	}
		1375
		1376	=head2 WATCHER STATES
		1377
		1378	There are various watcher states mentioned throughout this manual -
		1379	active, pending and so on. In this section these states and the rules to
		1380	transition between them will be described in more detail - and while these
		1381	rules might look complicated, they usually do "the right thing".
		1382
		1383	=over 4
		1384
		1385	=item initialiased
		1386
		1387	Before a watcher can be registered with the event looop it has to be
		1388	initialised. This can be done with a call to C<ev_TYPE_init>, or calls to
		1389	C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function.
		1390
		1391	In this state it is simply some block of memory that is suitable for use
		1392	in an event loop. It can be moved around, freed, reused etc. at will.
		1393
		1394	=item started/running/active
		1395
		1396	Once a watcher has been started with a call to C<ev_TYPE_start> it becomes
		1397	property of the event loop, and is actively waiting for events. While in
		1398	this state it cannot be accessed (except in a few documented ways), moved,
		1399	freed or anything else - the only legal thing is to keep a pointer to it,
		1400	and call libev functions on it that are documented to work on active watchers.
		1401
		1402	=item pending
		1403
		1404	If a watcher is active and libev determines that an event it is interested
		1405	in has occurred (such as a timer expiring), it will become pending. It will
		1406	stay in this pending state until either it is stopped or its callback is
		1407	about to be invoked, so it is not normally pending inside the watcher
		1408	callback.
		1409
		1410	The watcher might or might not be active while it is pending (for example,
		1411	an expired non-repeating timer can be pending but no longer active). If it
		1412	is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>),
		1413	but it is still property of the event loop at this time, so cannot be
		1414	moved, freed or reused. And if it is active the rules described in the
		1415	previous item still apply.
		1416
		1417	It is also possible to feed an event on a watcher that is not active (e.g.
		1418	via C<ev_feed_event>), in which case it becomes pending without being
		1419	active.
		1420
		1421	=item stopped
		1422
		1423	A watcher can be stopped implicitly by libev (in which case it might still
		1424	be pending), or explicitly by calling its C<ev_TYPE_stop> function. The
		1425	latter will clear any pending state the watcher might be in, regardless
		1426	of whether it was active or not, so stopping a watcher explicitly before
		1427	freeing it is often a good idea.
		1428
		1429	While stopped (and not pending) the watcher is essentially in the
		1430	initialised state, that is it can be reused, moved, modified in any way
		1431	you wish.
		1432
		1433	=back
1323		1434
1324	=head2 WATCHER PRIORITY MODELS	1435	=head2 WATCHER PRIORITY MODELS
1325		1436
1326	Many event loops support I<watcher priorities>, which are usually small	1437	Many event loops support I<watcher priorities>, which are usually small
1327	integers that influence the ordering of event callback invocation	1438	integers that influence the ordering of event callback invocation
…		…
1370		1481
1371	For example, to emulate how many other event libraries handle priorities,	1482	For example, to emulate how many other event libraries handle priorities,
1372	you can associate an C<ev_idle> watcher to each such watcher, and in	1483	you can associate an C<ev_idle> watcher to each such watcher, and in
1373	the normal watcher callback, you just start the idle watcher. The real	1484	the normal watcher callback, you just start the idle watcher. The real
1374	processing is done in the idle watcher callback. This causes libev to	1485	processing is done in the idle watcher callback. This causes libev to
1375	continously poll and process kernel event data for the watcher, but when	1486	continuously poll and process kernel event data for the watcher, but when
1376	the lock-out case is known to be rare (which in turn is rare :), this is	1487	the lock-out case is known to be rare (which in turn is rare :), this is
1377	workable.	1488	workable.
1378		1489
1379	Usually, however, the lock-out model implemented that way will perform	1490	Usually, however, the lock-out model implemented that way will perform
1380	miserably under the type of load it was designed to handle. In that case,	1491	miserably under the type of load it was designed to handle. In that case,
…		…
1394	{	1505	{
1395	// stop the I/O watcher, we received the event, but	1506	// stop the I/O watcher, we received the event, but
1396	// are not yet ready to handle it.	1507	// are not yet ready to handle it.
1397	ev_io_stop (EV_A_ w);	1508	ev_io_stop (EV_A_ w);
1398		1509
1399	// start the idle watcher to ahndle the actual event.	1510	// start the idle watcher to handle the actual event.
1400	// it will not be executed as long as other watchers	1511	// it will not be executed as long as other watchers
1401	// with the default priority are receiving events.	1512	// with the default priority are receiving events.
1402	ev_idle_start (EV_A_ &idle);	1513	ev_idle_start (EV_A_ &idle);
1403	}	1514	}
1404		1515
…		…
1458		1569
1459	If you cannot use non-blocking mode, then force the use of a	1570	If you cannot use non-blocking mode, then force the use of a
1460	known-to-be-good backend (at the time of this writing, this includes only	1571	known-to-be-good backend (at the time of this writing, this includes only
1461	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file	1572	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file
1462	descriptors for which non-blocking operation makes no sense (such as	1573	descriptors for which non-blocking operation makes no sense (such as
1463	files) - libev doesn't guarentee any specific behaviour in that case.	1574	files) - libev doesn't guarantee any specific behaviour in that case.
1464		1575
1465	Another thing you have to watch out for is that it is quite easy to	1576	Another thing you have to watch out for is that it is quite easy to
1466	receive "spurious" readiness notifications, that is your callback might	1577	receive "spurious" readiness notifications, that is your callback might
1467	be called with C<EV_READ> but a subsequent C<read>(2) will actually block	1578	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
1468	because there is no data. Not only are some backends known to create a	1579	because there is no data. Not only are some backends known to create a
…		…
1533		1644
1534	So when you encounter spurious, unexplained daemon exits, make sure you	1645	So when you encounter spurious, unexplained daemon exits, make sure you
1535	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon	1646	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon
1536	somewhere, as that would have given you a big clue).	1647	somewhere, as that would have given you a big clue).
1537		1648
		1649	=head3 The special problem of accept()ing when you can't
		1650
		1651	Many implementations of the POSIX C<accept> function (for example,
		1652	found in post-2004 Linux) have the peculiar behaviour of not removing a
		1653	connection from the pending queue in all error cases.
		1654
		1655	For example, larger servers often run out of file descriptors (because
		1656	of resource limits), causing C<accept> to fail with C<ENFILE> but not
		1657	rejecting the connection, leading to libev signalling readiness on
		1658	the next iteration again (the connection still exists after all), and
		1659	typically causing the program to loop at 100% CPU usage.
		1660
		1661	Unfortunately, the set of errors that cause this issue differs between
		1662	operating systems, there is usually little the app can do to remedy the
		1663	situation, and no known thread-safe method of removing the connection to
		1664	cope with overload is known (to me).
		1665
		1666	One of the easiest ways to handle this situation is to just ignore it
		1667	- when the program encounters an overload, it will just loop until the
		1668	situation is over. While this is a form of busy waiting, no OS offers an
		1669	event-based way to handle this situation, so it's the best one can do.
		1670
		1671	A better way to handle the situation is to log any errors other than
		1672	C<EAGAIN> and C<EWOULDBLOCK>, making sure not to flood the log with such
		1673	messages, and continue as usual, which at least gives the user an idea of
		1674	what could be wrong ("raise the ulimit!"). For extra points one could stop
		1675	the C<ev_io> watcher on the listening fd "for a while", which reduces CPU
		1676	usage.
		1677
		1678	If your program is single-threaded, then you could also keep a dummy file
		1679	descriptor for overload situations (e.g. by opening F</dev/null>), and
		1680	when you run into C<ENFILE> or C<EMFILE>, close it, run C<accept>,
		1681	close that fd, and create a new dummy fd. This will gracefully refuse
		1682	clients under typical overload conditions.
		1683
		1684	The last way to handle it is to simply log the error and C<exit>, as
		1685	is often done with C<malloc> failures, but this results in an easy
		1686	opportunity for a DoS attack.
1538		1687
1539	=head3 Watcher-Specific Functions	1688	=head3 Watcher-Specific Functions
1540		1689
1541	=over 4	1690	=over 4
1542		1691
…		…
1574	...	1723	...
1575	struct ev_loop *loop = ev_default_init (0);	1724	struct ev_loop *loop = ev_default_init (0);
1576	ev_io stdin_readable;	1725	ev_io stdin_readable;
1577	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1726	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1578	ev_io_start (loop, &stdin_readable);	1727	ev_io_start (loop, &stdin_readable);
1579	ev_loop (loop, 0);	1728	ev_run (loop, 0);
1580		1729
1581		1730
1582	=head2 C<ev_timer> - relative and optionally repeating timeouts	1731	=head2 C<ev_timer> - relative and optionally repeating timeouts
1583		1732
1584	Timer watchers are simple relative timers that generate an event after a	1733	Timer watchers are simple relative timers that generate an event after a
…		…
1593	The callback is guaranteed to be invoked only I<after> its timeout has	1742	The callback is guaranteed to be invoked only I<after> its timeout has
1594	passed (not I<at>, so on systems with very low-resolution clocks this	1743	passed (not I<at>, so on systems with very low-resolution clocks this
1595	might introduce a small delay). If multiple timers become ready during the	1744	might introduce a small delay). If multiple timers become ready during the
1596	same loop iteration then the ones with earlier time-out values are invoked	1745	same loop iteration then the ones with earlier time-out values are invoked
1597	before ones of the same priority with later time-out values (but this is	1746	before ones of the same priority with later time-out values (but this is
1598	no longer true when a callback calls C<ev_loop> recursively).	1747	no longer true when a callback calls C<ev_run> recursively).
1599		1748
1600	=head3 Be smart about timeouts	1749	=head3 Be smart about timeouts
1601		1750
1602	Many real-world problems involve some kind of timeout, usually for error	1751	Many real-world problems involve some kind of timeout, usually for error
1603	recovery. A typical example is an HTTP request - if the other side hangs,	1752	recovery. A typical example is an HTTP request - if the other side hangs,
…		…
1689	ev_tstamp timeout = last_activity + 60.;	1838	ev_tstamp timeout = last_activity + 60.;
1690		1839
1691	// if last_activity + 60. is older than now, we did time out	1840	// if last_activity + 60. is older than now, we did time out
1692	if (timeout < now)	1841	if (timeout < now)
1693	{	1842	{
1694	// timeout occured, take action	1843	// timeout occurred, take action
1695	}	1844	}
1696	else	1845	else
1697	{	1846	{
1698	// callback was invoked, but there was some activity, re-arm	1847	// callback was invoked, but there was some activity, re-arm
1699	// the watcher to fire in last_activity + 60, which is	1848	// the watcher to fire in last_activity + 60, which is
…		…
1721	to the current time (meaning we just have some activity :), then call the	1870	to the current time (meaning we just have some activity :), then call the
1722	callback, which will "do the right thing" and start the timer:	1871	callback, which will "do the right thing" and start the timer:
1723		1872
1724	ev_init (timer, callback);	1873	ev_init (timer, callback);
1725	last_activity = ev_now (loop);	1874	last_activity = ev_now (loop);
1726	callback (loop, timer, EV_TIMEOUT);	1875	callback (loop, timer, EV_TIMER);
1727		1876
1728	And when there is some activity, simply store the current time in	1877	And when there is some activity, simply store the current time in
1729	C<last_activity>, no libev calls at all:	1878	C<last_activity>, no libev calls at all:
1730		1879
1731	last_actiivty = ev_now (loop);	1880	last_activity = ev_now (loop);
1732		1881
1733	This technique is slightly more complex, but in most cases where the	1882	This technique is slightly more complex, but in most cases where the
1734	time-out is unlikely to be triggered, much more efficient.	1883	time-out is unlikely to be triggered, much more efficient.
1735		1884
1736	Changing the timeout is trivial as well (if it isn't hard-coded in the	1885	Changing the timeout is trivial as well (if it isn't hard-coded in the
…		…
1774		1923
1775	=head3 The special problem of time updates	1924	=head3 The special problem of time updates
1776		1925
1777	Establishing the current time is a costly operation (it usually takes at	1926	Establishing the current time is a costly operation (it usually takes at
1778	least two system calls): EV therefore updates its idea of the current	1927	least two system calls): EV therefore updates its idea of the current
1779	time only before and after C<ev_loop> collects new events, which causes a	1928	time only before and after C<ev_run> collects new events, which causes a
1780	growing difference between C<ev_now ()> and C<ev_time ()> when handling	1929	growing difference between C<ev_now ()> and C<ev_time ()> when handling
1781	lots of events in one iteration.	1930	lots of events in one iteration.
1782		1931
1783	The relative timeouts are calculated relative to the C<ev_now ()>	1932	The relative timeouts are calculated relative to the C<ev_now ()>
1784	time. This is usually the right thing as this timestamp refers to the time	1933	time. This is usually the right thing as this timestamp refers to the time
…		…
1862	Returns the remaining time until a timer fires. If the timer is active,	2011	Returns the remaining time until a timer fires. If the timer is active,
1863	then this time is relative to the current event loop time, otherwise it's	2012	then this time is relative to the current event loop time, otherwise it's
1864	the timeout value currently configured.	2013	the timeout value currently configured.
1865		2014
1866	That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns	2015	That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns
1867	C<5>. When the timer is started and one second passes, C<ev_timer_remain>	2016	C<5>. When the timer is started and one second passes, C<ev_timer_remaining>
1868	will return C<4>. When the timer expires and is restarted, it will return	2017	will return C<4>. When the timer expires and is restarted, it will return
1869	roughly C<7> (likely slightly less as callback invocation takes some time,	2018	roughly C<7> (likely slightly less as callback invocation takes some time,
1870	too), and so on.	2019	too), and so on.
1871		2020
1872	=item ev_tstamp repeat [read-write]	2021	=item ev_tstamp repeat [read-write]
…		…
1901	}	2050	}
1902		2051
1903	ev_timer mytimer;	2052	ev_timer mytimer;
1904	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	2053	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1905	ev_timer_again (&mytimer); /* start timer */	2054	ev_timer_again (&mytimer); /* start timer */
1906	ev_loop (loop, 0);	2055	ev_run (loop, 0);
1907		2056
1908	// and in some piece of code that gets executed on any "activity":	2057	// and in some piece of code that gets executed on any "activity":
1909	// reset the timeout to start ticking again at 10 seconds	2058	// reset the timeout to start ticking again at 10 seconds
1910	ev_timer_again (&mytimer);	2059	ev_timer_again (&mytimer);
1911		2060
…		…
1937		2086
1938	As with timers, the callback is guaranteed to be invoked only when the	2087	As with timers, the callback is guaranteed to be invoked only when the
1939	point in time where it is supposed to trigger has passed. If multiple	2088	point in time where it is supposed to trigger has passed. If multiple
1940	timers become ready during the same loop iteration then the ones with	2089	timers become ready during the same loop iteration then the ones with
1941	earlier time-out values are invoked before ones with later time-out values	2090	earlier time-out values are invoked before ones with later time-out values
1942	(but this is no longer true when a callback calls C<ev_loop> recursively).	2091	(but this is no longer true when a callback calls C<ev_run> recursively).
1943		2092
1944	=head3 Watcher-Specific Functions and Data Members	2093	=head3 Watcher-Specific Functions and Data Members
1945		2094
1946	=over 4	2095	=over 4
1947		2096
…		…
2075	Example: Call a callback every hour, or, more precisely, whenever the	2224	Example: Call a callback every hour, or, more precisely, whenever the
2076	system time is divisible by 3600. The callback invocation times have	2225	system time is divisible by 3600. The callback invocation times have
2077	potentially a lot of jitter, but good long-term stability.	2226	potentially a lot of jitter, but good long-term stability.
2078		2227
2079	static void	2228	static void
2080	clock_cb (struct ev_loop *loop, ev_io *w, int revents)	2229	clock_cb (struct ev_loop *loop, ev_periodic *w, int revents)
2081	{	2230	{
2082	... its now a full hour (UTC, or TAI or whatever your clock follows)	2231	... its now a full hour (UTC, or TAI or whatever your clock follows)
2083	}	2232	}
2084		2233
2085	ev_periodic hourly_tick;	2234	ev_periodic hourly_tick;
…		…
2132	C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should	2281	C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should
2133	not be unduly interrupted. If you have a problem with system calls getting	2282	not be unduly interrupted. If you have a problem with system calls getting
2134	interrupted by signals you can block all signals in an C<ev_check> watcher	2283	interrupted by signals you can block all signals in an C<ev_check> watcher
2135	and unblock them in an C<ev_prepare> watcher.	2284	and unblock them in an C<ev_prepare> watcher.
2136		2285
2137	=head3 The special problem of inheritance over execve	2286	=head3 The special problem of inheritance over fork/execve/pthread_create
2138		2287
2139	Both the signal mask (C<sigprocmask>) and the signal disposition	2288	Both the signal mask (C<sigprocmask>) and the signal disposition
2140	(C<sigaction>) are unspecified after starting a signal watcher (and after	2289	(C<sigaction>) are unspecified after starting a signal watcher (and after
2141	stopping it again), that is, libev might or might not block the signal,	2290	stopping it again), that is, libev might or might not block the signal,
2142	and might or might not set or restore the installed signal handler.	2291	and might or might not set or restore the installed signal handler.
…		…
2152		2301
2153	The simplest way to ensure that the signal mask is reset in the child is	2302	The simplest way to ensure that the signal mask is reset in the child is
2154	to install a fork handler with C<pthread_atfork> that resets it. That will	2303	to install a fork handler with C<pthread_atfork> that resets it. That will
2155	catch fork calls done by libraries (such as the libc) as well.	2304	catch fork calls done by libraries (such as the libc) as well.
2156		2305
2157	In current versions of libev, you can also ensure that the signal mask is	2306	In current versions of libev, the signal will not be blocked indefinitely
2158	not blocking any signals (except temporarily, so thread users watch out)	2307	unless you use the C<signalfd> API (C<EV_SIGNALFD>). While this reduces
2159	by specifying the C<EVFLAG_NOSIGFD> when creating the event loop. This	2308	the window of opportunity for problems, it will not go away, as libev
2160	is not guaranteed for future versions, however.	2309	I<has> to modify the signal mask, at least temporarily.
		2310
		2311	So I can't stress this enough: I<If you do not reset your signal mask when
		2312	you expect it to be empty, you have a race condition in your code>. This
		2313	is not a libev-specific thing, this is true for most event libraries.
2161		2314
2162	=head3 Watcher-Specific Functions and Data Members	2315	=head3 Watcher-Specific Functions and Data Members
2163		2316
2164	=over 4	2317	=over 4
2165		2318
…		…
2181	Example: Try to exit cleanly on SIGINT.	2334	Example: Try to exit cleanly on SIGINT.
2182		2335
2183	static void	2336	static void
2184	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)	2337	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)
2185	{	2338	{
2186	ev_unloop (loop, EVUNLOOP_ALL);	2339	ev_break (loop, EVBREAK_ALL);
2187	}	2340	}
2188		2341
2189	ev_signal signal_watcher;	2342	ev_signal signal_watcher;
2190	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	2343	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
2191	ev_signal_start (loop, &signal_watcher);	2344	ev_signal_start (loop, &signal_watcher);
…		…
2577		2730
2578	Prepare and check watchers are usually (but not always) used in pairs:	2731	Prepare and check watchers are usually (but not always) used in pairs:
2579	prepare watchers get invoked before the process blocks and check watchers	2732	prepare watchers get invoked before the process blocks and check watchers
2580	afterwards.	2733	afterwards.
2581		2734
2582	You I<must not> call C<ev_loop> or similar functions that enter	2735	You I<must not> call C<ev_run> or similar functions that enter
2583	the current event loop from either C<ev_prepare> or C<ev_check>	2736	the current event loop from either C<ev_prepare> or C<ev_check>
2584	watchers. Other loops than the current one are fine, however. The	2737	watchers. Other loops than the current one are fine, however. The
2585	rationale behind this is that you do not need to check for recursion in	2738	rationale behind this is that you do not need to check for recursion in
2586	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,	2739	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,
2587	C<ev_check> so if you have one watcher of each kind they will always be	2740	C<ev_check> so if you have one watcher of each kind they will always be
…		…
2755		2908
2756	if (timeout >= 0)	2909	if (timeout >= 0)
2757	// create/start timer	2910	// create/start timer
2758		2911
2759	// poll	2912	// poll
2760	ev_loop (EV_A_ 0);	2913	ev_run (EV_A_ 0);
2761		2914
2762	// stop timer again	2915	// stop timer again
2763	if (timeout >= 0)	2916	if (timeout >= 0)
2764	ev_timer_stop (EV_A_ &to);	2917	ev_timer_stop (EV_A_ &to);
2765		2918
…		…
2843	if you do not want that, you need to temporarily stop the embed watcher).	2996	if you do not want that, you need to temporarily stop the embed watcher).
2844		2997
2845	=item ev_embed_sweep (loop, ev_embed *)	2998	=item ev_embed_sweep (loop, ev_embed *)
2846		2999
2847	Make a single, non-blocking sweep over the embedded loop. This works	3000	Make a single, non-blocking sweep over the embedded loop. This works
2848	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	3001	similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most
2849	appropriate way for embedded loops.	3002	appropriate way for embedded loops.
2850		3003
2851	=item struct ev_loop *other [read-only]	3004	=item struct ev_loop *other [read-only]
2852		3005
2853	The embedded event loop.	3006	The embedded event loop.
…		…
2913	C<ev_default_fork> cheats and calls it in the wrong process, the fork	3066	C<ev_default_fork> cheats and calls it in the wrong process, the fork
2914	handlers will be invoked, too, of course.	3067	handlers will be invoked, too, of course.
2915		3068
2916	=head3 The special problem of life after fork - how is it possible?	3069	=head3 The special problem of life after fork - how is it possible?
2917		3070
2918	Most uses of C<fork()> consist of forking, then some simple calls to ste	3071	Most uses of C<fork()> consist of forking, then some simple calls to set
2919	up/change the process environment, followed by a call to C<exec()>. This	3072	up/change the process environment, followed by a call to C<exec()>. This
2920	sequence should be handled by libev without any problems.	3073	sequence should be handled by libev without any problems.
2921		3074
2922	This changes when the application actually wants to do event handling	3075	This changes when the application actually wants to do event handling
2923	in the child, or both parent in child, in effect "continuing" after the	3076	in the child, or both parent in child, in effect "continuing" after the
…		…
2939	disadvantage of having to use multiple event loops (which do not support	3092	disadvantage of having to use multiple event loops (which do not support
2940	signal watchers).	3093	signal watchers).
2941		3094
2942	When this is not possible, or you want to use the default loop for	3095	When this is not possible, or you want to use the default loop for
2943	other reasons, then in the process that wants to start "fresh", call	3096	other reasons, then in the process that wants to start "fresh", call
2944	C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying	3097	C<ev_loop_destroy (EV_DEFAULT)> followed by C<ev_default_loop (...)>.
2945	the default loop will "orphan" (not stop) all registered watchers, so you	3098	Destroying the default loop will "orphan" (not stop) all registered
2946	have to be careful not to execute code that modifies those watchers. Note	3099	watchers, so you have to be careful not to execute code that modifies
2947	also that in that case, you have to re-register any signal watchers.	3100	those watchers. Note also that in that case, you have to re-register any
		3101	signal watchers.
2948		3102
2949	=head3 Watcher-Specific Functions and Data Members	3103	=head3 Watcher-Specific Functions and Data Members
2950		3104
2951	=over 4	3105	=over 4
2952		3106
2953	=item ev_fork_init (ev_signal *, callback)	3107	=item ev_fork_init (ev_fork *, callback)
2954		3108
2955	Initialises and configures the fork watcher - it has no parameters of any	3109	Initialises and configures the fork watcher - it has no parameters of any
2956	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,	3110	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
2957	believe me.	3111	really.
2958		3112
2959	=back	3113	=back
2960		3114
2961		3115
		3116	=head2 C<ev_cleanup> - even the best things end
		3117
		3118	Cleanup watchers are called just before the event loop is being destroyed
		3119	by a call to C<ev_loop_destroy>.
		3120
		3121	While there is no guarantee that the event loop gets destroyed, cleanup
		3122	watchers provide a convenient method to install cleanup hooks for your
		3123	program, worker threads and so on - you just to make sure to destroy the
		3124	loop when you want them to be invoked.
		3125
		3126	Cleanup watchers are invoked in the same way as any other watcher. Unlike
		3127	all other watchers, they do not keep a reference to the event loop (which
		3128	makes a lot of sense if you think about it). Like all other watchers, you
		3129	can call libev functions in the callback, except C<ev_cleanup_start>.
		3130
		3131	=head3 Watcher-Specific Functions and Data Members
		3132
		3133	=over 4
		3134
		3135	=item ev_cleanup_init (ev_cleanup *, callback)
		3136
		3137	Initialises and configures the cleanup watcher - it has no parameters of
		3138	any kind. There is a C<ev_cleanup_set> macro, but using it is utterly
		3139	pointless, I assure you.
		3140
		3141	=back
		3142
		3143	Example: Register an atexit handler to destroy the default loop, so any
		3144	cleanup functions are called.
		3145
		3146	static void
		3147	program_exits (void)
		3148	{
		3149	ev_loop_destroy (EV_DEFAULT_UC);
		3150	}
		3151
		3152	...
		3153	atexit (program_exits);
		3154
		3155
2962	=head2 C<ev_async> - how to wake up another event loop	3156	=head2 C<ev_async> - how to wake up an event loop
2963		3157
2964	In general, you cannot use an C<ev_loop> from multiple threads or other	3158	In general, you cannot use an C<ev_run> from multiple threads or other
2965	asynchronous sources such as signal handlers (as opposed to multiple event	3159	asynchronous sources such as signal handlers (as opposed to multiple event
2966	loops - those are of course safe to use in different threads).	3160	loops - those are of course safe to use in different threads).
2967		3161
2968	Sometimes, however, you need to wake up another event loop you do not	3162	Sometimes, however, you need to wake up an event loop you do not control,
2969	control, for example because it belongs to another thread. This is what	3163	for example because it belongs to another thread. This is what C<ev_async>
2970	C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you	3164	watchers do: as long as the C<ev_async> watcher is active, you can signal
2971	can signal it by calling C<ev_async_send>, which is thread- and signal	3165	it by calling C<ev_async_send>, which is thread- and signal safe.
2972	safe.
2973		3166
2974	This functionality is very similar to C<ev_signal> watchers, as signals,	3167	This functionality is very similar to C<ev_signal> watchers, as signals,
2975	too, are asynchronous in nature, and signals, too, will be compressed	3168	too, are asynchronous in nature, and signals, too, will be compressed
2976	(i.e. the number of callback invocations may be less than the number of	3169	(i.e. the number of callback invocations may be less than the number of
2977	C<ev_async_sent> calls).	3170	C<ev_async_sent> calls).
…		…
3132		3325
3133	If C<timeout> is less than 0, then no timeout watcher will be	3326	If C<timeout> is less than 0, then no timeout watcher will be
3134	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and	3327	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and
3135	repeat = 0) will be started. C<0> is a valid timeout.	3328	repeat = 0) will be started. C<0> is a valid timeout.
3136		3329
3137	The callback has the type C<void (*cb)(int revents, void *arg)> and gets	3330	The callback has the type C<void (*cb)(int revents, void *arg)> and is
3138	passed an C<revents> set like normal event callbacks (a combination of	3331	passed an C<revents> set like normal event callbacks (a combination of
3139	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>	3332	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMER>) and the C<arg>
3140	value passed to C<ev_once>. Note that it is possible to receive I<both>	3333	value passed to C<ev_once>. Note that it is possible to receive I<both>
3141	a timeout and an io event at the same time - you probably should give io	3334	a timeout and an io event at the same time - you probably should give io
3142	events precedence.	3335	events precedence.
3143		3336
3144	Example: wait up to ten seconds for data to appear on STDIN_FILENO.	3337	Example: wait up to ten seconds for data to appear on STDIN_FILENO.
3145		3338
3146	static void stdin_ready (int revents, void *arg)	3339	static void stdin_ready (int revents, void *arg)
3147	{	3340	{
3148	if (revents & EV_READ)	3341	if (revents & EV_READ)
3149	/* stdin might have data for us, joy! */;	3342	/* stdin might have data for us, joy! */;
3150	else if (revents & EV_TIMEOUT)	3343	else if (revents & EV_TIMER)
3151	/* doh, nothing entered */;	3344	/* doh, nothing entered */;
3152	}	3345	}
3153		3346
3154	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	3347	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
3155		3348
…		…
3289	myclass obj;	3482	myclass obj;
3290	ev::io iow;	3483	ev::io iow;
3291	iow.set <myclass, &myclass::io_cb> (&obj);	3484	iow.set <myclass, &myclass::io_cb> (&obj);
3292		3485
3293	=item w->set (object *)	3486	=item w->set (object *)
3294
3295	This is an B<experimental> feature that might go away in a future version.
3296		3487
3297	This is a variation of a method callback - leaving out the method to call	3488	This is a variation of a method callback - leaving out the method to call
3298	will default the method to C<operator ()>, which makes it possible to use	3489	will default the method to C<operator ()>, which makes it possible to use
3299	functor objects without having to manually specify the C<operator ()> all	3490	functor objects without having to manually specify the C<operator ()> all
3300	the time. Incidentally, you can then also leave out the template argument	3491	the time. Incidentally, you can then also leave out the template argument
…		…
3340	Associates a different C<struct ev_loop> with this watcher. You can only	3531	Associates a different C<struct ev_loop> with this watcher. You can only
3341	do this when the watcher is inactive (and not pending either).	3532	do this when the watcher is inactive (and not pending either).
3342		3533
3343	=item w->set ([arguments])	3534	=item w->set ([arguments])
3344		3535
3345	Basically the same as C<ev_TYPE_set>, with the same arguments. Must be	3536	Basically the same as C<ev_TYPE_set>, with the same arguments. Either this
3346	called at least once. Unlike the C counterpart, an active watcher gets	3537	method or a suitable start method must be called at least once. Unlike the
3347	automatically stopped and restarted when reconfiguring it with this	3538	C counterpart, an active watcher gets automatically stopped and restarted
3348	method.	3539	when reconfiguring it with this method.
3349		3540
3350	=item w->start ()	3541	=item w->start ()
3351		3542
3352	Starts the watcher. Note that there is no C<loop> argument, as the	3543	Starts the watcher. Note that there is no C<loop> argument, as the
3353	constructor already stores the event loop.	3544	constructor already stores the event loop.
3354		3545
		3546	=item w->start ([arguments])
		3547
		3548	Instead of calling C<set> and C<start> methods separately, it is often
		3549	convenient to wrap them in one call. Uses the same type of arguments as
		3550	the configure C<set> method of the watcher.
		3551
3355	=item w->stop ()	3552	=item w->stop ()
3356		3553
3357	Stops the watcher if it is active. Again, no C<loop> argument.	3554	Stops the watcher if it is active. Again, no C<loop> argument.
3358		3555
3359	=item w->again () (C<ev::timer>, C<ev::periodic> only)	3556	=item w->again () (C<ev::timer>, C<ev::periodic> only)
…		…
3371		3568
3372	=back	3569	=back
3373		3570
3374	=back	3571	=back
3375		3572
3376	Example: Define a class with an IO and idle watcher, start one of them in	3573	Example: Define a class with two I/O and idle watchers, start the I/O
3377	the constructor.	3574	watchers in the constructor.
3378		3575
3379	class myclass	3576	class myclass
3380	{	3577	{
3381	ev::io io ; void io_cb (ev::io &w, int revents);	3578	ev::io io ; void io_cb (ev::io &w, int revents);
		3579	ev::io2 io2 ; void io2_cb (ev::io &w, int revents);
3382	ev::idle idle; void idle_cb (ev::idle &w, int revents);	3580	ev::idle idle; void idle_cb (ev::idle &w, int revents);
3383		3581
3384	myclass (int fd)	3582	myclass (int fd)
3385	{	3583	{
3386	io .set <myclass, &myclass::io_cb > (this);	3584	io .set <myclass, &myclass::io_cb > (this);
		3585	io2 .set <myclass, &myclass::io2_cb > (this);
3387	idle.set <myclass, &myclass::idle_cb> (this);	3586	idle.set <myclass, &myclass::idle_cb> (this);
3388		3587
3389	io.start (fd, ev::READ);	3588	io.set (fd, ev::WRITE); // configure the watcher
		3589	io.start (); // start it whenever convenient
		3590
		3591	io2.start (fd, ev::READ); // set + start in one call
3390	}	3592	}
3391	};	3593	};
3392		3594
3393		3595
3394	=head1 OTHER LANGUAGE BINDINGS	3596	=head1 OTHER LANGUAGE BINDINGS
…		…
3442	Erkki Seppala has written Ocaml bindings for libev, to be found at	3644	Erkki Seppala has written Ocaml bindings for libev, to be found at
3443	L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>.	3645	L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>.
3444		3646
3445	=item Lua	3647	=item Lua
3446		3648
3447	Brian Maher has written a partial interface to libev	3649	Brian Maher has written a partial interface to libev for lua (at the
3448	for lua (only C<ev_io> and C<ev_timer>), to be found at	3650	time of this writing, only C<ev_io> and C<ev_timer>), to be found at
3449	L<http://github.com/brimworks/lua-ev>.	3651	L<http://github.com/brimworks/lua-ev>.
3450		3652
3451	=back	3653	=back
3452		3654
3453		3655
…		…
3468	loop argument"). The C<EV_A> form is used when this is the sole argument,	3670	loop argument"). The C<EV_A> form is used when this is the sole argument,
3469	C<EV_A_> is used when other arguments are following. Example:	3671	C<EV_A_> is used when other arguments are following. Example:
3470		3672
3471	ev_unref (EV_A);	3673	ev_unref (EV_A);
3472	ev_timer_add (EV_A_ watcher);	3674	ev_timer_add (EV_A_ watcher);
3473	ev_loop (EV_A_ 0);	3675	ev_run (EV_A_ 0);
3474		3676
3475	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	3677	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
3476	which is often provided by the following macro.	3678	which is often provided by the following macro.
3477		3679
3478	=item C<EV_P>, C<EV_P_>	3680	=item C<EV_P>, C<EV_P_>
…		…
3518	}	3720	}
3519		3721
3520	ev_check check;	3722	ev_check check;
3521	ev_check_init (&check, check_cb);	3723	ev_check_init (&check, check_cb);
3522	ev_check_start (EV_DEFAULT_ &check);	3724	ev_check_start (EV_DEFAULT_ &check);
3523	ev_loop (EV_DEFAULT_ 0);	3725	ev_run (EV_DEFAULT_ 0);
3524		3726
3525	=head1 EMBEDDING	3727	=head1 EMBEDDING
3526		3728
3527	Libev can (and often is) directly embedded into host	3729	Libev can (and often is) directly embedded into host
3528	applications. Examples of applications that embed it include the Deliantra	3730	applications. Examples of applications that embed it include the Deliantra
…		…
3608	libev.m4	3810	libev.m4
3609		3811
3610	=head2 PREPROCESSOR SYMBOLS/MACROS	3812	=head2 PREPROCESSOR SYMBOLS/MACROS
3611		3813
3612	Libev can be configured via a variety of preprocessor symbols you have to	3814	Libev can be configured via a variety of preprocessor symbols you have to
3613	define before including any of its files. The default in the absence of	3815	define before including (or compiling) any of its files. The default in
3614	autoconf is documented for every option.	3816	the absence of autoconf is documented for every option.
		3817
		3818	Symbols marked with "(h)" do not change the ABI, and can have different
		3819	values when compiling libev vs. including F<ev.h>, so it is permissible
		3820	to redefine them before including F<ev.h> without breaking compatibility
		3821	to a compiled library. All other symbols change the ABI, which means all
		3822	users of libev and the libev code itself must be compiled with compatible
		3823	settings.
3615		3824
3616	=over 4	3825	=over 4
3617		3826
		3827	=item EV_COMPAT3 (h)
		3828
		3829	Backwards compatibility is a major concern for libev. This is why this
		3830	release of libev comes with wrappers for the functions and symbols that
		3831	have been renamed between libev version 3 and 4.
		3832
		3833	You can disable these wrappers (to test compatibility with future
		3834	versions) by defining C<EV_COMPAT3> to C<0> when compiling your
		3835	sources. This has the additional advantage that you can drop the C<struct>
		3836	from C<struct ev_loop> declarations, as libev will provide an C<ev_loop>
		3837	typedef in that case.
		3838
		3839	In some future version, the default for C<EV_COMPAT3> will become C<0>,
		3840	and in some even more future version the compatibility code will be
		3841	removed completely.
		3842
3618	=item EV_STANDALONE	3843	=item EV_STANDALONE (h)
3619		3844
3620	Must always be C<1> if you do not use autoconf configuration, which	3845	Must always be C<1> if you do not use autoconf configuration, which
3621	keeps libev from including F<config.h>, and it also defines dummy	3846	keeps libev from including F<config.h>, and it also defines dummy
3622	implementations for some libevent functions (such as logging, which is not	3847	implementations for some libevent functions (such as logging, which is not
3623	supported). It will also not define any of the structs usually found in	3848	supported). It will also not define any of the structs usually found in
…		…
3773	as well as for signal and thread safety in C<ev_async> watchers.	3998	as well as for signal and thread safety in C<ev_async> watchers.
3774		3999
3775	In the absence of this define, libev will use C<sig_atomic_t volatile>	4000	In the absence of this define, libev will use C<sig_atomic_t volatile>
3776	(from F<signal.h>), which is usually good enough on most platforms.	4001	(from F<signal.h>), which is usually good enough on most platforms.
3777		4002
3778	=item EV_H	4003	=item EV_H (h)
3779		4004
3780	The name of the F<ev.h> header file used to include it. The default if	4005	The name of the F<ev.h> header file used to include it. The default if
3781	undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be	4006	undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be
3782	used to virtually rename the F<ev.h> header file in case of conflicts.	4007	used to virtually rename the F<ev.h> header file in case of conflicts.
3783		4008
3784	=item EV_CONFIG_H	4009	=item EV_CONFIG_H (h)
3785		4010
3786	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override	4011	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override
3787	F<ev.c>'s idea of where to find the F<config.h> file, similarly to	4012	F<ev.c>'s idea of where to find the F<config.h> file, similarly to
3788	C<EV_H>, above.	4013	C<EV_H>, above.
3789		4014
3790	=item EV_EVENT_H	4015	=item EV_EVENT_H (h)
3791		4016
3792	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea	4017	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea
3793	of how the F<event.h> header can be found, the default is C<"event.h">.	4018	of how the F<event.h> header can be found, the default is C<"event.h">.
3794		4019
3795	=item EV_PROTOTYPES	4020	=item EV_PROTOTYPES (h)
3796		4021
3797	If defined to be C<0>, then F<ev.h> will not define any function	4022	If defined to be C<0>, then F<ev.h> will not define any function
3798	prototypes, but still define all the structs and other symbols. This is	4023	prototypes, but still define all the structs and other symbols. This is
3799	occasionally useful if you want to provide your own wrapper functions	4024	occasionally useful if you want to provide your own wrapper functions
3800	around libev functions.	4025	around libev functions.
…		…
3822	fine.	4047	fine.
3823		4048
3824	If your embedding application does not need any priorities, defining these	4049	If your embedding application does not need any priorities, defining these
3825	both to C<0> will save some memory and CPU.	4050	both to C<0> will save some memory and CPU.
3826		4051
3827	=item EV_PERIODIC_ENABLE	4052	=item EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE,
		4053	EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE,
		4054	EV_ASYNC_ENABLE, EV_CHILD_ENABLE.
3828		4055
3829	If undefined or defined to be C<1>, then periodic timers are supported. If	4056	If undefined or defined to be C<1> (and the platform supports it), then
3830	defined to be C<0>, then they are not. Disabling them saves a few kB of	4057	the respective watcher type is supported. If defined to be C<0>, then it
3831	code.	4058	is not. Disabling watcher types mainly saves code size.
3832		4059
3833	=item EV_IDLE_ENABLE	4060	=item EV_FEATURES
3834
3835	If undefined or defined to be C<1>, then idle watchers are supported. If
3836	defined to be C<0>, then they are not. Disabling them saves a few kB of
3837	code.
3838
3839	=item EV_EMBED_ENABLE
3840
3841	If undefined or defined to be C<1>, then embed watchers are supported. If
3842	defined to be C<0>, then they are not. Embed watchers rely on most other
3843	watcher types, which therefore must not be disabled.
3844
3845	=item EV_STAT_ENABLE
3846
3847	If undefined or defined to be C<1>, then stat watchers are supported. If
3848	defined to be C<0>, then they are not.
3849
3850	=item EV_FORK_ENABLE
3851
3852	If undefined or defined to be C<1>, then fork watchers are supported. If
3853	defined to be C<0>, then they are not.
3854
3855	=item EV_ASYNC_ENABLE
3856
3857	If undefined or defined to be C<1>, then async watchers are supported. If
3858	defined to be C<0>, then they are not.
3859
3860	=item EV_MINIMAL
3861		4061
3862	If you need to shave off some kilobytes of code at the expense of some	4062	If you need to shave off some kilobytes of code at the expense of some
3863	speed (but with the full API), define this symbol to C<1>. Currently this	4063	speed (but with the full API), you can define this symbol to request
3864	is used to override some inlining decisions, saves roughly 30% code size	4064	certain subsets of functionality. The default is to enable all features
3865	on amd64. It also selects a much smaller 2-heap for timer management over	4065	that can be enabled on the platform.
3866	the default 4-heap.
3867		4066
3868	You can save even more by disabling watcher types you do not need	4067	A typical way to use this symbol is to define it to C<0> (or to a bitset
3869	and setting C<EV_MAXPRI> == C<EV_MINPRI>. Also, disabling C<assert>	4068	with some broad features you want) and then selectively re-enable
3870	(C<-DNDEBUG>) will usually reduce code size a lot.	4069	additional parts you want, for example if you want everything minimal,
		4070	but multiple event loop support, async and child watchers and the poll
		4071	backend, use this:
3871		4072
3872	Defining C<EV_MINIMAL> to C<2> will additionally reduce the core API to	4073	#define EV_FEATURES 0
3873	provide a bare-bones event library. See C<ev.h> for details on what parts	4074	#define EV_MULTIPLICITY 1
3874	of the API are still available, and do not complain if this subset changes	4075	#define EV_USE_POLL 1
3875	over time.	4076	#define EV_CHILD_ENABLE 1
		4077	#define EV_ASYNC_ENABLE 1
		4078
		4079	The actual value is a bitset, it can be a combination of the following
		4080	values:
		4081
		4082	=over 4
		4083
		4084	=item C<1> - faster/larger code
		4085
		4086	Use larger code to speed up some operations.
		4087
		4088	Currently this is used to override some inlining decisions (enlarging the
		4089	code size by roughly 30% on amd64).
		4090
		4091	When optimising for size, use of compiler flags such as C<-Os> with
		4092	gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of
		4093	assertions.
		4094
		4095	=item C<2> - faster/larger data structures
		4096
		4097	Replaces the small 2-heap for timer management by a faster 4-heap, larger
		4098	hash table sizes and so on. This will usually further increase code size
		4099	and can additionally have an effect on the size of data structures at
		4100	runtime.
		4101
		4102	=item C<4> - full API configuration
		4103
		4104	This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and
		4105	enables multiplicity (C<EV_MULTIPLICITY>=1).
		4106
		4107	=item C<8> - full API
		4108
		4109	This enables a lot of the "lesser used" API functions. See C<ev.h> for
		4110	details on which parts of the API are still available without this
		4111	feature, and do not complain if this subset changes over time.
		4112
		4113	=item C<16> - enable all optional watcher types
		4114
		4115	Enables all optional watcher types. If you want to selectively enable
		4116	only some watcher types other than I/O and timers (e.g. prepare,
		4117	embed, async, child...) you can enable them manually by defining
		4118	C<EV_watchertype_ENABLE> to C<1> instead.
		4119
		4120	=item C<32> - enable all backends
		4121
		4122	This enables all backends - without this feature, you need to enable at
		4123	least one backend manually (C<EV_USE_SELECT> is a good choice).
		4124
		4125	=item C<64> - enable OS-specific "helper" APIs
		4126
		4127	Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by
		4128	default.
		4129
		4130	=back
		4131
		4132	Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0>
		4133	reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb
		4134	code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O
		4135	watchers, timers and monotonic clock support.
		4136
		4137	With an intelligent-enough linker (gcc+binutils are intelligent enough
		4138	when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by
		4139	your program might be left out as well - a binary starting a timer and an
		4140	I/O watcher then might come out at only 5Kb.
		4141
		4142	=item EV_AVOID_STDIO
		4143
		4144	If this is set to C<1> at compiletime, then libev will avoid using stdio
		4145	functions (printf, scanf, perror etc.). This will increase the code size
		4146	somewhat, but if your program doesn't otherwise depend on stdio and your
		4147	libc allows it, this avoids linking in the stdio library which is quite
		4148	big.
		4149
		4150	Note that error messages might become less precise when this option is
		4151	enabled.
3876		4152
3877	=item EV_NSIG	4153	=item EV_NSIG
3878		4154
3879	The highest supported signal number, +1 (or, the number of	4155	The highest supported signal number, +1 (or, the number of
3880	signals): Normally, libev tries to deduce the maximum number of signals	4156	signals): Normally, libev tries to deduce the maximum number of signals
3881	automatically, but sometimes this fails, in which case it can be	4157	automatically, but sometimes this fails, in which case it can be
3882	specified. Also, using a lower number than detected (C<32> should be	4158	specified. Also, using a lower number than detected (C<32> should be
3883	good for about any system in existance) can save some memory, as libev	4159	good for about any system in existence) can save some memory, as libev
3884	statically allocates some 12-24 bytes per signal number.	4160	statically allocates some 12-24 bytes per signal number.
3885		4161
3886	=item EV_PID_HASHSIZE	4162	=item EV_PID_HASHSIZE
3887		4163
3888	C<ev_child> watchers use a small hash table to distribute workload by	4164	C<ev_child> watchers use a small hash table to distribute workload by
3889	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more	4165	pid. The default size is C<16> (or C<1> with C<EV_FEATURES> disabled),
3890	than enough. If you need to manage thousands of children you might want to	4166	usually more than enough. If you need to manage thousands of children you
3891	increase this value (I<must> be a power of two).	4167	might want to increase this value (I<must> be a power of two).
3892		4168
3893	=item EV_INOTIFY_HASHSIZE	4169	=item EV_INOTIFY_HASHSIZE
3894		4170
3895	C<ev_stat> watchers use a small hash table to distribute workload by	4171	C<ev_stat> watchers use a small hash table to distribute workload by
3896	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),	4172	inotify watch id. The default size is C<16> (or C<1> with C<EV_FEATURES>
3897	usually more than enough. If you need to manage thousands of C<ev_stat>	4173	disabled), usually more than enough. If you need to manage thousands of
3898	watchers you might want to increase this value (I<must> be a power of	4174	C<ev_stat> watchers you might want to increase this value (I<must> be a
3899	two).	4175	power of two).
3900		4176
3901	=item EV_USE_4HEAP	4177	=item EV_USE_4HEAP
3902		4178
3903	Heaps are not very cache-efficient. To improve the cache-efficiency of the	4179	Heaps are not very cache-efficient. To improve the cache-efficiency of the
3904	timer and periodics heaps, libev uses a 4-heap when this symbol is defined	4180	timer and periodics heaps, libev uses a 4-heap when this symbol is defined
3905	to C<1>. The 4-heap uses more complicated (longer) code but has noticeably	4181	to C<1>. The 4-heap uses more complicated (longer) code but has noticeably
3906	faster performance with many (thousands) of watchers.	4182	faster performance with many (thousands) of watchers.
3907		4183
3908	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>	4184	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3909	(disabled).	4185	will be C<0>.
3910		4186
3911	=item EV_HEAP_CACHE_AT	4187	=item EV_HEAP_CACHE_AT
3912		4188
3913	Heaps are not very cache-efficient. To improve the cache-efficiency of the	4189	Heaps are not very cache-efficient. To improve the cache-efficiency of the
3914	timer and periodics heaps, libev can cache the timestamp (I<at>) within	4190	timer and periodics heaps, libev can cache the timestamp (I<at>) within
3915	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),	4191	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),
3916	which uses 8-12 bytes more per watcher and a few hundred bytes more code,	4192	which uses 8-12 bytes more per watcher and a few hundred bytes more code,
3917	but avoids random read accesses on heap changes. This improves performance	4193	but avoids random read accesses on heap changes. This improves performance
3918	noticeably with many (hundreds) of watchers.	4194	noticeably with many (hundreds) of watchers.
3919		4195
3920	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>	4196	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3921	(disabled).	4197	will be C<0>.
3922		4198
3923	=item EV_VERIFY	4199	=item EV_VERIFY
3924		4200
3925	Controls how much internal verification (see C<ev_loop_verify ()>) will	4201	Controls how much internal verification (see C<ev_verify ()>) will
3926	be done: If set to C<0>, no internal verification code will be compiled	4202	be done: If set to C<0>, no internal verification code will be compiled
3927	in. If set to C<1>, then verification code will be compiled in, but not	4203	in. If set to C<1>, then verification code will be compiled in, but not
3928	called. If set to C<2>, then the internal verification code will be	4204	called. If set to C<2>, then the internal verification code will be
3929	called once per loop, which can slow down libev. If set to C<3>, then the	4205	called once per loop, which can slow down libev. If set to C<3>, then the
3930	verification code will be called very frequently, which will slow down	4206	verification code will be called very frequently, which will slow down
3931	libev considerably.	4207	libev considerably.
3932		4208
3933	The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be	4209	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3934	C<0>.	4210	will be C<0>.
3935		4211
3936	=item EV_COMMON	4212	=item EV_COMMON
3937		4213
3938	By default, all watchers have a C<void *data> member. By redefining	4214	By default, all watchers have a C<void *data> member. By redefining
3939	this macro to a something else you can include more and other types of	4215	this macro to something else you can include more and other types of
3940	members. You have to define it each time you include one of the files,	4216	members. You have to define it each time you include one of the files,
3941	though, and it must be identical each time.	4217	though, and it must be identical each time.
3942		4218
3943	For example, the perl EV module uses something like this:	4219	For example, the perl EV module uses something like this:
3944		4220
…		…
3997	file.	4273	file.
3998		4274
3999	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	4275	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
4000	that everybody includes and which overrides some configure choices:	4276	that everybody includes and which overrides some configure choices:
4001		4277
4002	#define EV_MINIMAL 1	4278	#define EV_FEATURES 8
4003	#define EV_USE_POLL 0	4279	#define EV_USE_SELECT 1
4004	#define EV_MULTIPLICITY 0
4005	#define EV_PERIODIC_ENABLE 0	4280	#define EV_PREPARE_ENABLE 1
		4281	#define EV_IDLE_ENABLE 1
4006	#define EV_STAT_ENABLE 0	4282	#define EV_SIGNAL_ENABLE 1
4007	#define EV_FORK_ENABLE 0	4283	#define EV_CHILD_ENABLE 1
		4284	#define EV_USE_STDEXCEPT 0
4008	#define EV_CONFIG_H <config.h>	4285	#define EV_CONFIG_H <config.h>
4009	#define EV_MINPRI 0
4010	#define EV_MAXPRI 0
4011		4286
4012	#include "ev++.h"	4287	#include "ev++.h"
4013		4288
4014	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	4289	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
4015		4290
…		…
4146	userdata *u = ev_userdata (EV_A);	4421	userdata *u = ev_userdata (EV_A);
4147	pthread_mutex_lock (&u->lock);	4422	pthread_mutex_lock (&u->lock);
4148	}	4423	}
4149		4424
4150	The event loop thread first acquires the mutex, and then jumps straight	4425	The event loop thread first acquires the mutex, and then jumps straight
4151	into C<ev_loop>:	4426	into C<ev_run>:
4152		4427
4153	void *	4428	void *
4154	l_run (void *thr_arg)	4429	l_run (void *thr_arg)
4155	{	4430	{
4156	struct ev_loop *loop = (struct ev_loop *)thr_arg;	4431	struct ev_loop *loop = (struct ev_loop *)thr_arg;
4157		4432
4158	l_acquire (EV_A);	4433	l_acquire (EV_A);
4159	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);	4434	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
4160	ev_loop (EV_A_ 0);	4435	ev_run (EV_A_ 0);
4161	l_release (EV_A);	4436	l_release (EV_A);
4162		4437
4163	return 0;	4438	return 0;
4164	}	4439	}
4165		4440
…		…
4217		4492
4218	=head3 COROUTINES	4493	=head3 COROUTINES
4219		4494
4220	Libev is very accommodating to coroutines ("cooperative threads"):	4495	Libev is very accommodating to coroutines ("cooperative threads"):
4221	libev fully supports nesting calls to its functions from different	4496	libev fully supports nesting calls to its functions from different
4222	coroutines (e.g. you can call C<ev_loop> on the same loop from two	4497	coroutines (e.g. you can call C<ev_run> on the same loop from two
4223	different coroutines, and switch freely between both coroutines running	4498	different coroutines, and switch freely between both coroutines running
4224	the loop, as long as you don't confuse yourself). The only exception is	4499	the loop, as long as you don't confuse yourself). The only exception is
4225	that you must not do this from C<ev_periodic> reschedule callbacks.	4500	that you must not do this from C<ev_periodic> reschedule callbacks.
4226		4501
4227	Care has been taken to ensure that libev does not keep local state inside	4502	Care has been taken to ensure that libev does not keep local state inside
4228	C<ev_loop>, and other calls do not usually allow for coroutine switches as	4503	C<ev_run>, and other calls do not usually allow for coroutine switches as
4229	they do not call any callbacks.	4504	they do not call any callbacks.
4230		4505
4231	=head2 COMPILER WARNINGS	4506	=head2 COMPILER WARNINGS
4232		4507
4233	Depending on your compiler and compiler settings, you might get no or a	4508	Depending on your compiler and compiler settings, you might get no or a
…		…
4244	maintainable.	4519	maintainable.
4245		4520
4246	And of course, some compiler warnings are just plain stupid, or simply	4521	And of course, some compiler warnings are just plain stupid, or simply
4247	wrong (because they don't actually warn about the condition their message	4522	wrong (because they don't actually warn about the condition their message
4248	seems to warn about). For example, certain older gcc versions had some	4523	seems to warn about). For example, certain older gcc versions had some
4249	warnings that resulted an extreme number of false positives. These have	4524	warnings that resulted in an extreme number of false positives. These have
4250	been fixed, but some people still insist on making code warn-free with	4525	been fixed, but some people still insist on making code warn-free with
4251	such buggy versions.	4526	such buggy versions.
4252		4527
4253	While libev is written to generate as few warnings as possible,	4528	While libev is written to generate as few warnings as possible,
4254	"warn-free" code is not a goal, and it is recommended not to build libev	4529	"warn-free" code is not a goal, and it is recommended not to build libev
…		…
4290	I suggest using suppression lists.	4565	I suggest using suppression lists.
4291		4566
4292		4567
4293	=head1 PORTABILITY NOTES	4568	=head1 PORTABILITY NOTES
4294		4569
		4570	=head2 GNU/LINUX 32 BIT LIMITATIONS
		4571
		4572	GNU/Linux is the only common platform that supports 64 bit file/large file
		4573	interfaces but I<disables> them by default.
		4574
		4575	That means that libev compiled in the default environment doesn't support
		4576	files larger than 2GiB or so, which mainly affects C<ev_stat> watchers.
		4577
		4578	Unfortunately, many programs try to work around this GNU/Linux issue
		4579	by enabling the large file API, which makes them incompatible with the
		4580	standard libev compiled for their system.
		4581
		4582	Likewise, libev cannot enable the large file API itself as this would
		4583	suddenly make it incompatible to the default compile time environment,
		4584	i.e. all programs not using special compile switches.
		4585
		4586	=head2 OS/X AND DARWIN BUGS
		4587
		4588	The whole thing is a bug if you ask me - basically any system interface
		4589	you touch is broken, whether it is locales, poll, kqueue or even the
		4590	OpenGL drivers.
		4591
		4592	=head3 C<kqueue> is buggy
		4593
		4594	The kqueue syscall is broken in all known versions - most versions support
		4595	only sockets, many support pipes.
		4596
		4597	Libev tries to work around this by not using C<kqueue> by default on this
		4598	rotten platform, but of course you can still ask for it when creating a
		4599	loop - embedding a socket-only kqueue loop into a select-based one is
		4600	probably going to work well.
		4601
		4602	=head3 C<poll> is buggy
		4603
		4604	Instead of fixing C<kqueue>, Apple replaced their (working) C<poll>
		4605	implementation by something calling C<kqueue> internally around the 10.5.6
		4606	release, so now C<kqueue> I<and> C<poll> are broken.
		4607
		4608	Libev tries to work around this by not using C<poll> by default on
		4609	this rotten platform, but of course you can still ask for it when creating
		4610	a loop.
		4611
		4612	=head3 C<select> is buggy
		4613
		4614	All that's left is C<select>, and of course Apple found a way to fuck this
		4615	one up as well: On OS/X, C<select> actively limits the number of file
		4616	descriptors you can pass in to 1024 - your program suddenly crashes when
		4617	you use more.
		4618
		4619	There is an undocumented "workaround" for this - defining
		4620	C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should>
		4621	work on OS/X.
		4622
		4623	=head2 SOLARIS PROBLEMS AND WORKAROUNDS
		4624
		4625	=head3 C<errno> reentrancy
		4626
		4627	The default compile environment on Solaris is unfortunately so
		4628	thread-unsafe that you can't even use components/libraries compiled
		4629	without C<-D_REENTRANT> in a threaded program, which, of course, isn't
		4630	defined by default. A valid, if stupid, implementation choice.
		4631
		4632	If you want to use libev in threaded environments you have to make sure
		4633	it's compiled with C<_REENTRANT> defined.
		4634
		4635	=head3 Event port backend
		4636
		4637	The scalable event interface for Solaris is called "event
		4638	ports". Unfortunately, this mechanism is very buggy in all major
		4639	releases. If you run into high CPU usage, your program freezes or you get
		4640	a large number of spurious wakeups, make sure you have all the relevant
		4641	and latest kernel patches applied. No, I don't know which ones, but there
		4642	are multiple ones to apply, and afterwards, event ports actually work
		4643	great.
		4644
		4645	If you can't get it to work, you can try running the program by setting
		4646	the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and
		4647	C<select> backends.
		4648
		4649	=head2 AIX POLL BUG
		4650
		4651	AIX unfortunately has a broken C<poll.h> header. Libev works around
		4652	this by trying to avoid the poll backend altogether (i.e. it's not even
		4653	compiled in), which normally isn't a big problem as C<select> works fine
		4654	with large bitsets on AIX, and AIX is dead anyway.
		4655
4295	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS	4656	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
		4657
		4658	=head3 General issues
4296		4659
4297	Win32 doesn't support any of the standards (e.g. POSIX) that libev	4660	Win32 doesn't support any of the standards (e.g. POSIX) that libev
4298	requires, and its I/O model is fundamentally incompatible with the POSIX	4661	requires, and its I/O model is fundamentally incompatible with the POSIX
4299	model. Libev still offers limited functionality on this platform in	4662	model. Libev still offers limited functionality on this platform in
4300	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	4663	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
4301	descriptors. This only applies when using Win32 natively, not when using	4664	descriptors. This only applies when using Win32 natively, not when using
4302	e.g. cygwin.	4665	e.g. cygwin. Actually, it only applies to the microsofts own compilers,
		4666	as every compielr comes with a slightly differently broken/incompatible
		4667	environment.
4303		4668
4304	Lifting these limitations would basically require the full	4669	Lifting these limitations would basically require the full
4305	re-implementation of the I/O system. If you are into these kinds of	4670	re-implementation of the I/O system. If you are into this kind of thing,
4306	things, then note that glib does exactly that for you in a very portable	4671	then note that glib does exactly that for you in a very portable way (note
4307	way (note also that glib is the slowest event library known to man).	4672	also that glib is the slowest event library known to man).
4308		4673
4309	There is no supported compilation method available on windows except	4674	There is no supported compilation method available on windows except
4310	embedding it into other applications.	4675	embedding it into other applications.
4311		4676
4312	Sensible signal handling is officially unsupported by Microsoft - libev	4677	Sensible signal handling is officially unsupported by Microsoft - libev
…		…
4340	you do I<not> compile the F<ev.c> or any other embedded source files!):	4705	you do I<not> compile the F<ev.c> or any other embedded source files!):
4341		4706
4342	#include "evwrap.h"	4707	#include "evwrap.h"
4343	#include "ev.c"	4708	#include "ev.c"
4344		4709
4345	=over 4
4346
4347	=item The winsocket select function	4710	=head3 The winsocket C<select> function
4348		4711
4349	The winsocket C<select> function doesn't follow POSIX in that it	4712	The winsocket C<select> function doesn't follow POSIX in that it
4350	requires socket I<handles> and not socket I<file descriptors> (it is	4713	requires socket I<handles> and not socket I<file descriptors> (it is
4351	also extremely buggy). This makes select very inefficient, and also	4714	also extremely buggy). This makes select very inefficient, and also
4352	requires a mapping from file descriptors to socket handles (the Microsoft	4715	requires a mapping from file descriptors to socket handles (the Microsoft
…		…
4361	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */	4724	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
4362		4725
4363	Note that winsockets handling of fd sets is O(n), so you can easily get a	4726	Note that winsockets handling of fd sets is O(n), so you can easily get a
4364	complexity in the O(n²) range when using win32.	4727	complexity in the O(n²) range when using win32.
4365		4728
4366	=item Limited number of file descriptors	4729	=head3 Limited number of file descriptors
4367		4730
4368	Windows has numerous arbitrary (and low) limits on things.	4731	Windows has numerous arbitrary (and low) limits on things.
4369		4732
4370	Early versions of winsocket's select only supported waiting for a maximum	4733	Early versions of winsocket's select only supported waiting for a maximum
4371	of C<64> handles (probably owning to the fact that all windows kernels	4734	of C<64> handles (probably owning to the fact that all windows kernels
…		…
4386	runtime libraries. This might get you to about C<512> or C<2048> sockets	4749	runtime libraries. This might get you to about C<512> or C<2048> sockets
4387	(depending on windows version and/or the phase of the moon). To get more,	4750	(depending on windows version and/or the phase of the moon). To get more,
4388	you need to wrap all I/O functions and provide your own fd management, but	4751	you need to wrap all I/O functions and provide your own fd management, but
4389	the cost of calling select (O(n²)) will likely make this unworkable.	4752	the cost of calling select (O(n²)) will likely make this unworkable.
4390		4753
4391	=back
4392
4393	=head2 PORTABILITY REQUIREMENTS	4754	=head2 PORTABILITY REQUIREMENTS
4394		4755
4395	In addition to a working ISO-C implementation and of course the	4756	In addition to a working ISO-C implementation and of course the
4396	backend-specific APIs, libev relies on a few additional extensions:	4757	backend-specific APIs, libev relies on a few additional extensions:
4397		4758
…		…
4403	Libev assumes not only that all watcher pointers have the same internal	4764	Libev assumes not only that all watcher pointers have the same internal
4404	structure (guaranteed by POSIX but not by ISO C for example), but it also	4765	structure (guaranteed by POSIX but not by ISO C for example), but it also
4405	assumes that the same (machine) code can be used to call any watcher	4766	assumes that the same (machine) code can be used to call any watcher
4406	callback: The watcher callbacks have different type signatures, but libev	4767	callback: The watcher callbacks have different type signatures, but libev
4407	calls them using an C<ev_watcher *> internally.	4768	calls them using an C<ev_watcher *> internally.
		4769
		4770	=item pointer accesses must be thread-atomic
		4771
		4772	Accessing a pointer value must be atomic, it must both be readable and
		4773	writable in one piece - this is the case on all current architectures.
4408		4774
4409	=item C<sig_atomic_t volatile> must be thread-atomic as well	4775	=item C<sig_atomic_t volatile> must be thread-atomic as well
4410		4776
4411	The type C<sig_atomic_t volatile> (or whatever is defined as	4777	The type C<sig_atomic_t volatile> (or whatever is defined as
4412	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different	4778	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different
…		…
4435	watchers.	4801	watchers.
4436		4802
4437	=item C<double> must hold a time value in seconds with enough accuracy	4803	=item C<double> must hold a time value in seconds with enough accuracy
4438		4804
4439	The type C<double> is used to represent timestamps. It is required to	4805	The type C<double> is used to represent timestamps. It is required to
4440	have at least 51 bits of mantissa (and 9 bits of exponent), which is good	4806	have at least 51 bits of mantissa (and 9 bits of exponent), which is
4441	enough for at least into the year 4000. This requirement is fulfilled by	4807	good enough for at least into the year 4000 with millisecond accuracy
		4808	(the design goal for libev). This requirement is overfulfilled by
4442	implementations implementing IEEE 754, which is basically all existing	4809	implementations using IEEE 754, which is basically all existing ones. With
4443	ones. With IEEE 754 doubles, you get microsecond accuracy until at least	4810	IEEE 754 doubles, you get microsecond accuracy until at least 2200.
4444	2200.
4445		4811
4446	=back	4812	=back
4447		4813
4448	If you know of other additional requirements drop me a note.	4814	If you know of other additional requirements drop me a note.
4449		4815
…		…
4517	involves iterating over all running async watchers or all signal numbers.	4883	involves iterating over all running async watchers or all signal numbers.
4518		4884
4519	=back	4885	=back
4520		4886
4521		4887
		4888	=head1 PORTING FROM LIBEV 3.X TO 4.X
		4889
		4890	The major version 4 introduced some incompatible changes to the API.
		4891
		4892	At the moment, the C<ev.h> header file provides compatibility definitions
		4893	for all changes, so most programs should still compile. The compatibility
		4894	layer might be removed in later versions of libev, so better update to the
		4895	new API early than late.
		4896
		4897	=over 4
		4898
		4899	=item C<EV_COMPAT3> backwards compatibility mechanism
		4900
		4901	The backward compatibility mechanism can be controlled by
		4902	C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING>
		4903	section.
		4904
		4905	=item C<ev_default_destroy> and C<ev_default_fork> have been removed
		4906
		4907	These calls can be replaced easily by their C<ev_loop_xxx> counterparts:
		4908
		4909	ev_loop_destroy (EV_DEFAULT_UC);
		4910	ev_loop_fork (EV_DEFAULT);
		4911
		4912	=item function/symbol renames
		4913
		4914	A number of functions and symbols have been renamed:
		4915
		4916	ev_loop => ev_run
		4917	EVLOOP_NONBLOCK => EVRUN_NOWAIT
		4918	EVLOOP_ONESHOT => EVRUN_ONCE
		4919
		4920	ev_unloop => ev_break
		4921	EVUNLOOP_CANCEL => EVBREAK_CANCEL
		4922	EVUNLOOP_ONE => EVBREAK_ONE
		4923	EVUNLOOP_ALL => EVBREAK_ALL
		4924
		4925	EV_TIMEOUT => EV_TIMER
		4926
		4927	ev_loop_count => ev_iteration
		4928	ev_loop_depth => ev_depth
		4929	ev_loop_verify => ev_verify
		4930
		4931	Most functions working on C<struct ev_loop> objects don't have an
		4932	C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and
		4933	associated constants have been renamed to not collide with the C<struct
		4934	ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme
		4935	as all other watcher types. Note that C<ev_loop_fork> is still called
		4936	C<ev_loop_fork> because it would otherwise clash with the C<ev_fork>
		4937	typedef.
		4938
		4939	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>
		4940
		4941	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different
		4942	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile
		4943	and work, but the library code will of course be larger.
		4944
		4945	=back
		4946
		4947
4522	=head1 GLOSSARY	4948	=head1 GLOSSARY
4523		4949
4524	=over 4	4950	=over 4
4525		4951
4526	=item active	4952	=item active
4527		4953
4528	A watcher is active as long as it has been started (has been attached to	4954	A watcher is active as long as it has been started and not yet stopped.
4529	an event loop) but not yet stopped (disassociated from the event loop).	4955	See L<WATCHER STATES> for details.
4530		4956
4531	=item application	4957	=item application
4532		4958
4533	In this document, an application is whatever is using libev.	4959	In this document, an application is whatever is using libev.
		4960
		4961	=item backend
		4962
		4963	The part of the code dealing with the operating system interfaces.
4534		4964
4535	=item callback	4965	=item callback
4536		4966
4537	The address of a function that is called when some event has been	4967	The address of a function that is called when some event has been
4538	detected. Callbacks are being passed the event loop, the watcher that	4968	detected. Callbacks are being passed the event loop, the watcher that
4539	received the event, and the actual event bitset.	4969	received the event, and the actual event bitset.
4540		4970
4541	=item callback invocation	4971	=item callback/watcher invocation
4542		4972
4543	The act of calling the callback associated with a watcher.	4973	The act of calling the callback associated with a watcher.
4544		4974
4545	=item event	4975	=item event
4546		4976
4547	A change of state of some external event, such as data now being available	4977	A change of state of some external event, such as data now being available
4548	for reading on a file descriptor, time having passed or simply not having	4978	for reading on a file descriptor, time having passed or simply not having
4549	any other events happening anymore.	4979	any other events happening anymore.
4550		4980
4551	In libev, events are represented as single bits (such as C<EV_READ> or	4981	In libev, events are represented as single bits (such as C<EV_READ> or
4552	C<EV_TIMEOUT>).	4982	C<EV_TIMER>).
4553		4983
4554	=item event library	4984	=item event library
4555		4985
4556	A software package implementing an event model and loop.	4986	A software package implementing an event model and loop.
4557		4987
…		…
4565	The model used to describe how an event loop handles and processes	4995	The model used to describe how an event loop handles and processes
4566	watchers and events.	4996	watchers and events.
4567		4997
4568	=item pending	4998	=item pending
4569		4999
4570	A watcher is pending as soon as the corresponding event has been detected,	5000	A watcher is pending as soon as the corresponding event has been
4571	and stops being pending as soon as the watcher will be invoked or its	5001	detected. See L<WATCHER STATES> for details.
4572	pending status is explicitly cleared by the application.
4573
4574	A watcher can be pending, but not active. Stopping a watcher also clears
4575	its pending status.
4576		5002
4577	=item real time	5003	=item real time
4578		5004
4579	The physical time that is observed. It is apparently strictly monotonic :)	5005	The physical time that is observed. It is apparently strictly monotonic :)
4580		5006
…		…
4587	=item watcher	5013	=item watcher
4588		5014
4589	A data structure that describes interest in certain events. Watchers need	5015	A data structure that describes interest in certain events. Watchers need
4590	to be started (attached to an event loop) before they can receive events.	5016	to be started (attached to an event loop) before they can receive events.
4591		5017
4592	=item watcher invocation
4593
4594	The act of calling the callback associated with a watcher.
4595
4596	=back	5018	=back
4597		5019
4598	=head1 AUTHOR	5020	=head1 AUTHOR
4599		5021
4600	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson.	5022	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael
		5023	Magnusson and Emanuele Giaquinta.
4601		5024

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