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Revision 1.275 by root, Sat Dec 26 09:21:54 2009 UTC vs.
Revision 1.348 by sf-exg, Sat Jan 8 17:52:39 2011 UTC

…		…
26	puts ("stdin ready");	26	puts ("stdin ready");
27	// for one-shot events, one must manually stop the watcher	27	// for one-shot events, one must manually stop the watcher
28	// with its corresponding stop function.	28	// with its corresponding stop function.
29	ev_io_stop (EV_A_ w);	29	ev_io_stop (EV_A_ w);
30		30
31	// this causes all nested ev_loop's to stop iterating	31	// this causes all nested ev_run's to stop iterating
32	ev_unloop (EV_A_ EVUNLOOP_ALL);	32	ev_break (EV_A_ EVBREAK_ALL);
33	}	33	}
34		34
35	// another callback, this time for a time-out	35	// another callback, this time for a time-out
36	static void	36	static void
37	timeout_cb (EV_P_ ev_timer *w, int revents)	37	timeout_cb (EV_P_ ev_timer *w, int revents)
38	{	38	{
39	puts ("timeout");	39	puts ("timeout");
40	// this causes the innermost ev_loop to stop iterating	40	// this causes the innermost ev_run to stop iterating
41	ev_unloop (EV_A_ EVUNLOOP_ONE);	41	ev_break (EV_A_ EVBREAK_ONE);
42	}	42	}
43		43
44	int	44	int
45	main (void)	45	main (void)
46	{	46	{
47	// use the default event loop unless you have special needs	47	// use the default event loop unless you have special needs
48	struct ev_loop *loop = ev_default_loop (0);	48	struct ev_loop *loop = EV_DEFAULT;
49		49
50	// initialise an io watcher, then start it	50	// initialise an io watcher, then start it
51	// this one will watch for stdin to become readable	51	// this one will watch for stdin to become readable
52	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);	52	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);
53	ev_io_start (loop, &stdin_watcher);	53	ev_io_start (loop, &stdin_watcher);
…		…
56	// simple non-repeating 5.5 second timeout	56	// simple non-repeating 5.5 second timeout
57	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);	57	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
58	ev_timer_start (loop, &timeout_watcher);	58	ev_timer_start (loop, &timeout_watcher);
59		59
60	// now wait for events to arrive	60	// now wait for events to arrive
61	ev_loop (loop, 0);	61	ev_run (loop, 0);
62		62
63	// unloop was called, so exit	63	// unloop was called, so exit
64	return 0;	64	return 0;
65	}	65	}
66		66
…		…
75	While this document tries to be as complete as possible in documenting	75	While this document tries to be as complete as possible in documenting
76	libev, its usage and the rationale behind its design, it is not a tutorial	76	libev, its usage and the rationale behind its design, it is not a tutorial
77	on event-based programming, nor will it introduce event-based programming	77	on event-based programming, nor will it introduce event-based programming
78	with libev.	78	with libev.
79		79
80	Familarity with event based programming techniques in general is assumed	80	Familiarity with event based programming techniques in general is assumed
81	throughout this document.	81	throughout this document.
		82
		83	=head1 WHAT TO READ WHEN IN A HURRY
		84
		85	This manual tries to be very detailed, but unfortunately, this also makes
		86	it very long. If you just want to know the basics of libev, I suggest
		87	reading L<ANATOMY OF A WATCHER>, then the L<EXAMPLE PROGRAM> above and
		88	look up the missing functions in L<GLOBAL FUNCTIONS> and the C<ev_io> and
		89	C<ev_timer> sections in L<WATCHER TYPES>.
82		90
83	=head1 ABOUT LIBEV	91	=head1 ABOUT LIBEV
84		92
85	Libev is an event loop: you register interest in certain events (such as a	93	Libev is an event loop: you register interest in certain events (such as a
86	file descriptor being readable or a timeout occurring), and it will manage	94	file descriptor being readable or a timeout occurring), and it will manage
…		…
124	this argument.	132	this argument.
125		133
126	=head2 TIME REPRESENTATION	134	=head2 TIME REPRESENTATION
127		135
128	Libev represents time as a single floating point number, representing	136	Libev represents time as a single floating point number, representing
129	the (fractional) number of seconds since the (POSIX) epoch (somewhere	137	the (fractional) number of seconds since the (POSIX) epoch (in practice
130	near the beginning of 1970, details are complicated, don't ask). This	138	somewhere near the beginning of 1970, details are complicated, don't
131	type is called C<ev_tstamp>, which is what you should use too. It usually	139	ask). This type is called C<ev_tstamp>, which is what you should use
132	aliases to the C<double> type in C. When you need to do any calculations	140	too. It usually aliases to the C<double> type in C. When you need to do
133	on it, you should treat it as some floating point value. Unlike the name	141	any calculations on it, you should treat it as some floating point value.
		142
134	component C<stamp> might indicate, it is also used for time differences	143	Unlike the name component C<stamp> might indicate, it is also used for
135	throughout libev.	144	time differences (e.g. delays) throughout libev.
136		145
137	=head1 ERROR HANDLING	146	=head1 ERROR HANDLING
138		147
139	Libev knows three classes of errors: operating system errors, usage errors	148	Libev knows three classes of errors: operating system errors, usage errors
140	and internal errors (bugs).	149	and internal errors (bugs).
…		…
164		173
165	=item ev_tstamp ev_time ()	174	=item ev_tstamp ev_time ()
166		175
167	Returns the current time as libev would use it. Please note that the	176	Returns the current time as libev would use it. Please note that the
168	C<ev_now> function is usually faster and also often returns the timestamp	177	C<ev_now> function is usually faster and also often returns the timestamp
169	you actually want to know.	178	you actually want to know. Also interesting is the combination of
		179	C<ev_update_now> and C<ev_now>.
170		180
171	=item ev_sleep (ev_tstamp interval)	181	=item ev_sleep (ev_tstamp interval)
172		182
173	Sleep for the given interval: The current thread will be blocked until	183	Sleep for the given interval: The current thread will be blocked until
174	either it is interrupted or the given time interval has passed. Basically	184	either it is interrupted or the given time interval has passed. Basically
…		…
191	as this indicates an incompatible change. Minor versions are usually	201	as this indicates an incompatible change. Minor versions are usually
192	compatible to older versions, so a larger minor version alone is usually	202	compatible to older versions, so a larger minor version alone is usually
193	not a problem.	203	not a problem.
194		204
195	Example: Make sure we haven't accidentally been linked against the wrong	205	Example: Make sure we haven't accidentally been linked against the wrong
196	version.	206	version (note, however, that this will not detect other ABI mismatches,
		207	such as LFS or reentrancy).
197		208
198	assert (("libev version mismatch",	209	assert (("libev version mismatch",
199	ev_version_major () == EV_VERSION_MAJOR	210	ev_version_major () == EV_VERSION_MAJOR
200	&& ev_version_minor () >= EV_VERSION_MINOR));	211	&& ev_version_minor () >= EV_VERSION_MINOR));
201		212
…		…
212	assert (("sorry, no epoll, no sex",	223	assert (("sorry, no epoll, no sex",
213	ev_supported_backends () & EVBACKEND_EPOLL));	224	ev_supported_backends () & EVBACKEND_EPOLL));
214		225
215	=item unsigned int ev_recommended_backends ()	226	=item unsigned int ev_recommended_backends ()
216		227
217	Return the set of all backends compiled into this binary of libev and also	228	Return the set of all backends compiled into this binary of libev and
218	recommended for this platform. This set is often smaller than the one	229	also recommended for this platform, meaning it will work for most file
		230	descriptor types. This set is often smaller than the one returned by
219	returned by C<ev_supported_backends>, as for example kqueue is broken on	231	C<ev_supported_backends>, as for example kqueue is broken on most BSDs
220	most BSDs and will not be auto-detected unless you explicitly request it	232	and will not be auto-detected unless you explicitly request it (assuming
221	(assuming you know what you are doing). This is the set of backends that	233	you know what you are doing). This is the set of backends that libev will
222	libev will probe for if you specify no backends explicitly.	234	probe for if you specify no backends explicitly.
223		235
224	=item unsigned int ev_embeddable_backends ()	236	=item unsigned int ev_embeddable_backends ()
225		237
226	Returns the set of backends that are embeddable in other event loops. This	238	Returns the set of backends that are embeddable in other event loops. This
227	is the theoretical, all-platform, value. To find which backends	239	value is platform-specific but can include backends not available on the
228	might be supported on the current system, you would need to look at	240	current system. To find which embeddable backends might be supported on
229	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for	241	the current system, you would need to look at C<ev_embeddable_backends ()
230	recommended ones.	242	& ev_supported_backends ()>, likewise for recommended ones.
231		243
232	See the description of C<ev_embed> watchers for more info.	244	See the description of C<ev_embed> watchers for more info.
233		245
234	=item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT]	246	=item ev_set_allocator (void *(*cb)(void *ptr, long size))
235		247
236	Sets the allocation function to use (the prototype is similar - the	248	Sets the allocation function to use (the prototype is similar - the
237	semantics are identical to the C<realloc> C89/SuS/POSIX function). It is	249	semantics are identical to the C<realloc> C89/SuS/POSIX function). It is
238	used to allocate and free memory (no surprises here). If it returns zero	250	used to allocate and free memory (no surprises here). If it returns zero
239	when memory needs to be allocated (C<size != 0>), the library might abort	251	when memory needs to be allocated (C<size != 0>), the library might abort
…		…
265	}	277	}
266		278
267	...	279	...
268	ev_set_allocator (persistent_realloc);	280	ev_set_allocator (persistent_realloc);
269		281
270	=item ev_set_syserr_cb (void (*cb)(const char *msg)); [NOT REENTRANT]	282	=item ev_set_syserr_cb (void (*cb)(const char *msg))
271		283
272	Set the callback function to call on a retryable system call error (such	284	Set the callback function to call on a retryable system call error (such
273	as failed select, poll, epoll_wait). The message is a printable string	285	as failed select, poll, epoll_wait). The message is a printable string
274	indicating the system call or subsystem causing the problem. If this	286	indicating the system call or subsystem causing the problem. If this
275	callback is set, then libev will expect it to remedy the situation, no	287	callback is set, then libev will expect it to remedy the situation, no
…		…
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	This function is thread-safe, and one common way to use libev with
		361	threads is indeed to create one loop per thread, and using the default
		362	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
…		…
366	environment variable.	402	environment variable.
367		403
368	=item C<EVFLAG_NOINOTIFY>	404	=item C<EVFLAG_NOINOTIFY>
369		405
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 its 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 its 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, resulting in additional iterations
		470	(and only giving 5ms accuracy while select on the same platform gives
428	so on. The biggest issue is fork races, however - if a program forks then	471	0.1ms) and so on. The biggest issue is fork races, however - if a program
429	I<both> parent and child process have to recreate the epoll set, which can	472	forks then I<both> parent and child process have to recreate the epoll
430	take considerable time (one syscall per file descriptor) and is of course	473	set, which can take considerable time (one syscall per file descriptor)
431	hard to detect.	474	and is of course hard to detect.
432		475
433	Epoll is also notoriously buggy - embedding epoll fds I<should> work, but	476	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	477	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	478	I<different> file descriptors (even already closed ones, so one cannot
436	even remove them from the set) than registered in the set (especially	479	even remove them from the set) than registered in the set (especially
437	on SMP systems). Libev tries to counter these spurious notifications by	480	on SMP systems). Libev tries to counter these spurious notifications by
438	employing an additional generation counter and comparing that against the	481	employing an additional generation counter and comparing that against the
439	events to filter out spurious ones, recreating the set when required.	482	events to filter out spurious ones, recreating the set when required. Last
		483	not least, it also refuses to work with some file descriptors which work
		484	perfectly fine with C<select> (files, many character devices...).
		485
		486	Epoll is truly the train wreck analog among event poll mechanisms.
440		487
441	While stopping, setting and starting an I/O watcher in the same iteration	488	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	489	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	490	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	491	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,	589	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	590	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	591	here). If none are specified, all backends in C<ev_recommended_backends
545	()> will be tried.	592	()> will be tried.
546		593
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.	594	Example: Try to create a event loop that uses epoll and nothing else.
576		595
577	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	596	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
578	if (!epoller)	597	if (!epoller)
579	fatal ("no epoll found here, maybe it hides under your chair");	598	fatal ("no epoll found here, maybe it hides under your chair");
580		599
		600	Example: Use whatever libev has to offer, but make sure that kqueue is
		601	used if available.
		602
		603	struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE);
		604
581	=item ev_default_destroy ()	605	=item ev_loop_destroy (loop)
582		606
583	Destroys the default loop again (frees all memory and kernel state	607	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	608	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	609	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>	610	responsibility to either stop all watchers cleanly yourself I<before>
587	calling this function, or cope with the fact afterwards (which is usually	611	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	612	the easiest thing, you can just ignore the watchers and/or C<free ()> them
…		…
590		614
591	Note that certain global state, such as signal state (and installed signal	615	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	616	handlers), will not be freed by this function, and related watchers (such
593	as signal and child watchers) would need to be stopped manually.	617	as signal and child watchers) would need to be stopped manually.
594		618
595	In general it is not advisable to call this function except in the	619	This function is normally used on loop objects allocated by
596	rare occasion where you really need to free e.g. the signal handling	620	C<ev_loop_new>, but it can also be used on the default loop returned by
		621	C<ev_default_loop>, in which case it is not thread-safe.
		622
		623	Note that it is not advisable to call this function on the default loop
		624	except in the rare occasion where you really need to free its resources.
597	pipe fds. If you need dynamically allocated loops it is better to use	625	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>.	626	and C<ev_loop_destroy>.
599		627
600	=item ev_loop_destroy (loop)	628	=item ev_loop_fork (loop)
601		629
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	630	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	631	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	632	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	633	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	634	child before resuming or calling C<ev_run>.
612	functions, and it will only take effect at the next C<ev_loop> iteration.	635
		636	Again, you I<have> to call it on I<any> loop that you want to re-use after
		637	a fork, I<even if you do not plan to use the loop in the parent>. This is
		638	because some kernel interfaces *cough* I<kqueue> *cough* do funny things
		639	during fork.
613		640
614	On the other hand, you only need to call this function in the child	641	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	642	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.	643	you just fork+exec or create a new loop in the child, you don't have to
		644	call it at all (in fact, C<epoll> is so badly broken that it makes a
		645	difference, but libev will usually detect this case on its own and do a
		646	costly reset of the backend).
617		647
618	The function itself is quite fast and it's usually not a problem to call	648	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	649	it just in case after a fork.
620	quite nicely into a call to C<pthread_atfork>:
621		650
		651	Example: Automate calling C<ev_loop_fork> on the default loop when
		652	using pthreads.
		653
		654	static void
		655	post_fork_child (void)
		656	{
		657	ev_loop_fork (EV_DEFAULT);
		658	}
		659
		660	...
622	pthread_atfork (0, 0, ev_default_fork);	661	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		662
631	=item int ev_is_default_loop (loop)	663	=item int ev_is_default_loop (loop)
632		664
633	Returns true when the given loop is, in fact, the default loop, and false	665	Returns true when the given loop is, in fact, the default loop, and false
634	otherwise.	666	otherwise.
635		667
636	=item unsigned int ev_loop_count (loop)	668	=item unsigned int ev_iteration (loop)
637		669
638	Returns the count of loop iterations for the loop, which is identical to	670	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	671	to the number of times libev did poll for new events. It starts at C<0>
640	happily wraps around with enough iterations.	672	and happily wraps around with enough iterations.
641		673
642	This value can sometimes be useful as a generation counter of sorts (it	674	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	675	"ticks" the number of loop iterations), as it roughly corresponds with
644	C<ev_prepare> and C<ev_check> calls.	676	C<ev_prepare> and C<ev_check> calls - and is incremented between the
		677	prepare and check phases.
645		678
646	=item unsigned int ev_loop_depth (loop)	679	=item unsigned int ev_depth (loop)
647		680
648	Returns the number of times C<ev_loop> was entered minus the number of	681	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.	682	times C<ev_run> was exited normally, in other words, the recursion depth.
650		683
651	Outside C<ev_loop>, this number is zero. In a callback, this number is	684	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),	685	C<1>, unless C<ev_run> was invoked recursively (or from another thread),
653	in which case it is higher.	686	in which case it is higher.
654		687
655	Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread	688	Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread,
656	etc.), doesn't count as exit.	689	throwing an exception etc.), doesn't count as "exit" - consider this
		690	as a hint to avoid such ungentleman-like behaviour unless it's really
		691	convenient, in which case it is fully supported.
657		692
658	=item unsigned int ev_backend (loop)	693	=item unsigned int ev_backend (loop)
659		694
660	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	695	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
661	use.	696	use.
…		…
670		705
671	=item ev_now_update (loop)	706	=item ev_now_update (loop)
672		707
673	Establishes the current time by querying the kernel, updating the time	708	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	709	returned by C<ev_now ()> in the progress. This is a costly operation and
675	is usually done automatically within C<ev_loop ()>.	710	is usually done automatically within C<ev_run ()>.
676		711
677	This function is rarely useful, but when some event callback runs for a	712	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	713	very long time without entering the event loop, updating libev's idea of
679	the current time is a good idea.	714	the current time is a good idea.
680		715
…		…
682		717
683	=item ev_suspend (loop)	718	=item ev_suspend (loop)
684		719
685	=item ev_resume (loop)	720	=item ev_resume (loop)
686		721
687	These two functions suspend and resume a loop, for use when the loop is	722	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.	723	loop is not used for a while and timeouts should not be processed.
689		724
690	A typical use case would be an interactive program such as a game: When	725	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	726	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	727	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>	728	the program was suspended. This can be achieved by calling C<ev_suspend>
…		…
695	C<ev_resume> directly afterwards to resume timer processing.	730	C<ev_resume> directly afterwards to resume timer processing.
696		731
697	Effectively, all C<ev_timer> watchers will be delayed by the time spend	732	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	733	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	734	will be rescheduled (that is, they will lose any events that would have
700	occured while suspended).	735	occurred while suspended).
701		736
702	After calling C<ev_suspend> you B<must not> call I<any> function on the	737	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>	738	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>.	739	without a previous call to C<ev_suspend>.
705		740
706	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the	741	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the
707	event loop time (see C<ev_now_update>).	742	event loop time (see C<ev_now_update>).
708		743
709	=item ev_loop (loop, int flags)	744	=item ev_run (loop, int flags)
710		745
711	Finally, this is it, the event handler. This function usually is called	746	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	747	after you have initialised all your watchers and you want to start
713	handling events.	748	handling events. It will ask the operating system for any new events, call
		749	the watcher callbacks, an then repeat the whole process indefinitely: This
		750	is why event loops are called I<loops>.
714		751
715	If the flags argument is specified as C<0>, it will not return until	752	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.	753	until either no event watchers are active anymore or C<ev_break> was
		754	called.
717		755
718	Please note that an explicit C<ev_unloop> is usually better than	756	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	757	relying on all watchers to be stopped when deciding when a program has
720	finished (especially in interactive programs), but having a program	758	finished (especially in interactive programs), but having a program
721	that automatically loops as long as it has to and no longer by virtue	759	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	760	of relying on its watchers stopping correctly, that is truly a thing of
723	beauty.	761	beauty.
724		762
		763	This function is also I<mostly> exception-safe - you can break out of
		764	a C<ev_run> call by calling C<longjmp> in a callback, throwing a C++
		765	exception and so on. This does not decrement the C<ev_depth> value, nor
		766	will it clear any outstanding C<EVBREAK_ONE> breaks.
		767
725	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle	768	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	769	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	770	block your process in case there are no events and will return after one
728	the loop.	771	iteration of the loop. This is sometimes useful to poll and handle new
		772	events while doing lengthy calculations, to keep the program responsive.
729		773
730	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if	774	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	775	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	776	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	777	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	778	user-registered callback will be called), and will return after one
735	iteration of the loop.	779	iteration of the loop.
736		780
737	This is useful if you are waiting for some external event in conjunction	781	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	782	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	783	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.	784	usually a better approach for this kind of thing.
741		785
742	Here are the gory details of what C<ev_loop> does:	786	Here are the gory details of what C<ev_run> does:
743		787
		788	- Increment loop depth.
		789	- Reset the ev_break status.
744	- Before the first iteration, call any pending watchers.	790	- Before the first iteration, call any pending watchers.
		791	LOOP:
745	* If EVFLAG_FORKCHECK was used, check for a fork.	792	- If EVFLAG_FORKCHECK was used, check for a fork.
746	- If a fork was detected (by any means), queue and call all fork watchers.	793	- If a fork was detected (by any means), queue and call all fork watchers.
747	- Queue and call all prepare watchers.	794	- Queue and call all prepare watchers.
		795	- If ev_break was called, goto FINISH.
748	- If we have been forked, detach and recreate the kernel state	796	- If we have been forked, detach and recreate the kernel state
749	as to not disturb the other process.	797	as to not disturb the other process.
750	- Update the kernel state with all outstanding changes.	798	- Update the kernel state with all outstanding changes.
751	- Update the "event loop time" (ev_now ()).	799	- Update the "event loop time" (ev_now ()).
752	- Calculate for how long to sleep or block, if at all	800	- Calculate for how long to sleep or block, if at all
753	(active idle watchers, EVLOOP_NONBLOCK or not having	801	(active idle watchers, EVRUN_NOWAIT or not having
754	any active watchers at all will result in not sleeping).	802	any active watchers at all will result in not sleeping).
755	- Sleep if the I/O and timer collect interval say so.	803	- Sleep if the I/O and timer collect interval say so.
		804	- Increment loop iteration counter.
756	- Block the process, waiting for any events.	805	- Block the process, waiting for any events.
757	- Queue all outstanding I/O (fd) events.	806	- Queue all outstanding I/O (fd) events.
758	- Update the "event loop time" (ev_now ()), and do time jump adjustments.	807	- Update the "event loop time" (ev_now ()), and do time jump adjustments.
759	- Queue all expired timers.	808	- Queue all expired timers.
760	- Queue all expired periodics.	809	- Queue all expired periodics.
761	- Unless any events are pending now, queue all idle watchers.	810	- Queue all idle watchers with priority higher than that of pending events.
762	- Queue all check watchers.	811	- Queue all check watchers.
763	- Call all queued watchers in reverse order (i.e. check watchers first).	812	- 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	813	Signals and child watchers are implemented as I/O watchers, and will
765	be handled here by queueing them when their watcher gets executed.	814	be handled here by queueing them when their watcher gets executed.
766	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	815	- If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT
767	were used, or there are no active watchers, return, otherwise	816	were used, or there are no active watchers, goto FINISH, otherwise
768	continue with step *.	817	continue with step LOOP.
		818	FINISH:
		819	- Reset the ev_break status iff it was EVBREAK_ONE.
		820	- Decrement the loop depth.
		821	- Return.
769		822
770	Example: Queue some jobs and then loop until no events are outstanding	823	Example: Queue some jobs and then loop until no events are outstanding
771	anymore.	824	anymore.
772		825
773	... queue jobs here, make sure they register event watchers as long	826	... 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..)	827	... as they still have work to do (even an idle watcher will do..)
775	ev_loop (my_loop, 0);	828	ev_run (my_loop, 0);
776	... jobs done or somebody called unloop. yeah!	829	... jobs done or somebody called unloop. yeah!
777		830
778	=item ev_unloop (loop, how)	831	=item ev_break (loop, how)
779		832
780	Can be used to make a call to C<ev_loop> return early (but only after it	833	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	834	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	835	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.	836	C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return.
784		837
785	This "unloop state" will be cleared when entering C<ev_loop> again.	838	This "break state" will be cleared on the next call to C<ev_run>.
786		839
787	It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls.	840	It is safe to call C<ev_break> from outside any C<ev_run> calls, too, in
		841	which case it will have no effect.
788		842
789	=item ev_ref (loop)	843	=item ev_ref (loop)
790		844
791	=item ev_unref (loop)	845	=item ev_unref (loop)
792		846
793	Ref/unref can be used to add or remove a reference count on the event	847	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	848	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.	849	count is nonzero, C<ev_run> will not return on its own.
796		850
797	If you have a watcher you never unregister that should not keep C<ev_loop>	851	This is useful when you have a watcher that you never intend to
798	from returning, call ev_unref() after starting, and ev_ref() before	852	unregister, but that nevertheless should not keep C<ev_run> from
		853	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>
799	stopping it.	854	before stopping it.
800		855
801	As an example, libev itself uses this for its internal signal pipe: It	856	As an example, libev itself uses this for its internal signal pipe: It
802	is not visible to the libev user and should not keep C<ev_loop> from	857	is not visible to the libev user and should not keep C<ev_run> from
803	exiting if no event watchers registered by it are active. It is also an	858	exiting if no event watchers registered by it are active. It is also an
804	excellent way to do this for generic recurring timers or from within	859	excellent way to do this for generic recurring timers or from within
805	third-party libraries. Just remember to I<unref after start> and I<ref	860	third-party libraries. Just remember to I<unref after start> and I<ref
806	before stop> (but only if the watcher wasn't active before, or was active	861	before stop> (but only if the watcher wasn't active before, or was active
807	before, respectively. Note also that libev might stop watchers itself	862	before, respectively. Note also that libev might stop watchers itself
808	(e.g. non-repeating timers) in which case you have to C<ev_ref>	863	(e.g. non-repeating timers) in which case you have to C<ev_ref>
809	in the callback).	864	in the callback).
810		865
811	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	866	Example: Create a signal watcher, but keep it from keeping C<ev_run>
812	running when nothing else is active.	867	running when nothing else is active.
813		868
814	ev_signal exitsig;	869	ev_signal exitsig;
815	ev_signal_init (&exitsig, sig_cb, SIGINT);	870	ev_signal_init (&exitsig, sig_cb, SIGINT);
816	ev_signal_start (loop, &exitsig);	871	ev_signal_start (loop, &exitsig);
817	evf_unref (loop);	872	ev_unref (loop);
818		873
819	Example: For some weird reason, unregister the above signal handler again.	874	Example: For some weird reason, unregister the above signal handler again.
820		875
821	ev_ref (loop);	876	ev_ref (loop);
822	ev_signal_stop (loop, &exitsig);	877	ev_signal_stop (loop, &exitsig);
…		…
861	usually doesn't make much sense to set it to a lower value than C<0.01>,	916	usually doesn't make much sense to set it to a lower value than C<0.01>,
862	as this approaches the timing granularity of most systems. Note that if	917	as this approaches the timing granularity of most systems. Note that if
863	you do transactions with the outside world and you can't increase the	918	you do transactions with the outside world and you can't increase the
864	parallelity, then this setting will limit your transaction rate (if you	919	parallelity, then this setting will limit your transaction rate (if you
865	need to poll once per transaction and the I/O collect interval is 0.01,	920	need to poll once per transaction and the I/O collect interval is 0.01,
866	then you can't do more than 100 transations per second).	921	then you can't do more than 100 transactions per second).
867		922
868	Setting the I<timeout collect interval> can improve the opportunity for	923	Setting the I<timeout collect interval> can improve the opportunity for
869	saving power, as the program will "bundle" timer callback invocations that	924	saving power, as the program will "bundle" timer callback invocations that
870	are "near" in time together, by delaying some, thus reducing the number of	925	are "near" in time together, by delaying some, thus reducing the number of
871	times the process sleeps and wakes up again. Another useful technique to	926	times the process sleeps and wakes up again. Another useful technique to
…		…
879	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);	934	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);
880		935
881	=item ev_invoke_pending (loop)	936	=item ev_invoke_pending (loop)
882		937
883	This call will simply invoke all pending watchers while resetting their	938	This call will simply invoke all pending watchers while resetting their
884	pending state. Normally, C<ev_loop> does this automatically when required,	939	pending state. Normally, C<ev_run> does this automatically when required,
885	but when overriding the invoke callback this call comes handy.	940	but when overriding the invoke callback this call comes handy. This
		941	function can be invoked from a watcher - this can be useful for example
		942	when you want to do some lengthy calculation and want to pass further
		943	event handling to another thread (you still have to make sure only one
		944	thread executes within C<ev_invoke_pending> or C<ev_run> of course).
886		945
887	=item int ev_pending_count (loop)	946	=item int ev_pending_count (loop)
888		947
889	Returns the number of pending watchers - zero indicates that no watchers	948	Returns the number of pending watchers - zero indicates that no watchers
890	are pending.	949	are pending.
891		950
892	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))	951	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))
893		952
894	This overrides the invoke pending functionality of the loop: Instead of	953	This overrides the invoke pending functionality of the loop: Instead of
895	invoking all pending watchers when there are any, C<ev_loop> will call	954	invoking all pending watchers when there are any, C<ev_run> will call
896	this callback instead. This is useful, for example, when you want to	955	this callback instead. This is useful, for example, when you want to
897	invoke the actual watchers inside another context (another thread etc.).	956	invoke the actual watchers inside another context (another thread etc.).
898		957
899	If you want to reset the callback, use C<ev_invoke_pending> as new	958	If you want to reset the callback, use C<ev_invoke_pending> as new
900	callback.	959	callback.
…		…
903		962
904	Sometimes you want to share the same loop between multiple threads. This	963	Sometimes you want to share the same loop between multiple threads. This
905	can be done relatively simply by putting mutex_lock/unlock calls around	964	can be done relatively simply by putting mutex_lock/unlock calls around
906	each call to a libev function.	965	each call to a libev function.
907		966
908	However, C<ev_loop> can run an indefinite time, so it is not feasible to	967	However, C<ev_run> can run an indefinite time, so it is not feasible
909	wait for it to return. One way around this is to wake up the loop via	968	to wait for it to return. One way around this is to wake up the event
910	C<ev_unloop> and C<av_async_send>, another way is to set these I<release>	969	loop via C<ev_break> and C<av_async_send>, another way is to set these
911	and I<acquire> callbacks on the loop.	970	I<release> and I<acquire> callbacks on the loop.
912		971
913	When set, then C<release> will be called just before the thread is	972	When set, then C<release> will be called just before the thread is
914	suspended waiting for new events, and C<acquire> is called just	973	suspended waiting for new events, and C<acquire> is called just
915	afterwards.	974	afterwards.
916		975
…		…
919		978
920	While event loop modifications are allowed between invocations of	979	While event loop modifications are allowed between invocations of
921	C<release> and C<acquire> (that's their only purpose after all), no	980	C<release> and C<acquire> (that's their only purpose after all), no
922	modifications done will affect the event loop, i.e. adding watchers will	981	modifications done will affect the event loop, i.e. adding watchers will
923	have no effect on the set of file descriptors being watched, or the time	982	have no effect on the set of file descriptors being watched, or the time
924	waited. Use an C<ev_async> watcher to wake up C<ev_loop> when you want it	983	waited. Use an C<ev_async> watcher to wake up C<ev_run> when you want it
925	to take note of any changes you made.	984	to take note of any changes you made.
926		985
927	In theory, threads executing C<ev_loop> will be async-cancel safe between	986	In theory, threads executing C<ev_run> will be async-cancel safe between
928	invocations of C<release> and C<acquire>.	987	invocations of C<release> and C<acquire>.
929		988
930	See also the locking example in the C<THREADS> section later in this	989	See also the locking example in the C<THREADS> section later in this
931	document.	990	document.
932		991
933	=item ev_set_userdata (loop, void *data)	992	=item ev_set_userdata (loop, void *data)
934		993
935	=item ev_userdata (loop)	994	=item void *ev_userdata (loop)
936		995
937	Set and retrieve a single C<void *> associated with a loop. When	996	Set and retrieve a single C<void *> associated with a loop. When
938	C<ev_set_userdata> has never been called, then C<ev_userdata> returns	997	C<ev_set_userdata> has never been called, then C<ev_userdata> returns
939	C<0.>	998	C<0>.
940		999
941	These two functions can be used to associate arbitrary data with a loop,	1000	These two functions can be used to associate arbitrary data with a loop,
942	and are intended solely for the C<invoke_pending_cb>, C<release> and	1001	and are intended solely for the C<invoke_pending_cb>, C<release> and
943	C<acquire> callbacks described above, but of course can be (ab-)used for	1002	C<acquire> callbacks described above, but of course can be (ab-)used for
944	any other purpose as well.	1003	any other purpose as well.
945		1004
946	=item ev_loop_verify (loop)	1005	=item ev_verify (loop)
947		1006
948	This function only does something when C<EV_VERIFY> support has been	1007	This function only does something when C<EV_VERIFY> support has been
949	compiled in, which is the default for non-minimal builds. It tries to go	1008	compiled in, which is the default for non-minimal builds. It tries to go
950	through all internal structures and checks them for validity. If anything	1009	through all internal structures and checks them for validity. If anything
951	is found to be inconsistent, it will print an error message to standard	1010	is found to be inconsistent, it will print an error message to standard
…		…
962		1021
963	In the following description, uppercase C<TYPE> in names stands for the	1022	In the following description, uppercase C<TYPE> in names stands for the
964	watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer	1023	watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer
965	watchers and C<ev_io_start> for I/O watchers.	1024	watchers and C<ev_io_start> for I/O watchers.
966		1025
967	A watcher is a structure that you create and register to record your	1026	A watcher is an opaque structure that you allocate and register to record
968	interest in some event. For instance, if you want to wait for STDIN to	1027	your interest in some event. To make a concrete example, imagine you want
969	become readable, you would create an C<ev_io> watcher for that:	1028	to wait for STDIN to become readable, you would create an C<ev_io> watcher
		1029	for that:
970		1030
971	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)	1031	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)
972	{	1032	{
973	ev_io_stop (w);	1033	ev_io_stop (w);
974	ev_unloop (loop, EVUNLOOP_ALL);	1034	ev_break (loop, EVBREAK_ALL);
975	}	1035	}
976		1036
977	struct ev_loop *loop = ev_default_loop (0);	1037	struct ev_loop *loop = ev_default_loop (0);
978		1038
979	ev_io stdin_watcher;	1039	ev_io stdin_watcher;
980		1040
981	ev_init (&stdin_watcher, my_cb);	1041	ev_init (&stdin_watcher, my_cb);
982	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	1042	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
983	ev_io_start (loop, &stdin_watcher);	1043	ev_io_start (loop, &stdin_watcher);
984		1044
985	ev_loop (loop, 0);	1045	ev_run (loop, 0);
986		1046
987	As you can see, you are responsible for allocating the memory for your	1047	As you can see, you are responsible for allocating the memory for your
988	watcher structures (and it is I<usually> a bad idea to do this on the	1048	watcher structures (and it is I<usually> a bad idea to do this on the
989	stack).	1049	stack).
990		1050
991	Each watcher has an associated watcher structure (called C<struct ev_TYPE>	1051	Each watcher has an associated watcher structure (called C<struct ev_TYPE>
992	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).	1052	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).
993		1053
994	Each watcher structure must be initialised by a call to C<ev_init	1054	Each watcher structure must be initialised by a call to C<ev_init (watcher
995	(watcher *, callback)>, which expects a callback to be provided. This	1055	*, callback)>, which expects a callback to be provided. This callback is
996	callback gets invoked each time the event occurs (or, in the case of I/O	1056	invoked each time the event occurs (or, in the case of I/O watchers, each
997	watchers, each time the event loop detects that the file descriptor given	1057	time the event loop detects that the file descriptor given is readable
998	is readable and/or writable).	1058	and/or writable).
999		1059
1000	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>	1060	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>
1001	macro to configure it, with arguments specific to the watcher type. There	1061	macro to configure it, with arguments specific to the watcher type. There
1002	is also a macro to combine initialisation and setting in one call: C<<	1062	is also a macro to combine initialisation and setting in one call: C<<
1003	ev_TYPE_init (watcher *, callback, ...) >>.	1063	ev_TYPE_init (watcher *, callback, ...) >>.
…		…
1026	=item C<EV_WRITE>	1086	=item C<EV_WRITE>
1027		1087
1028	The file descriptor in the C<ev_io> watcher has become readable and/or	1088	The file descriptor in the C<ev_io> watcher has become readable and/or
1029	writable.	1089	writable.
1030		1090
1031	=item C<EV_TIMEOUT>	1091	=item C<EV_TIMER>
1032		1092
1033	The C<ev_timer> watcher has timed out.	1093	The C<ev_timer> watcher has timed out.
1034		1094
1035	=item C<EV_PERIODIC>	1095	=item C<EV_PERIODIC>
1036		1096
…		…
1054		1114
1055	=item C<EV_PREPARE>	1115	=item C<EV_PREPARE>
1056		1116
1057	=item C<EV_CHECK>	1117	=item C<EV_CHECK>
1058		1118
1059	All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts	1119	All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts
1060	to gather new events, and all C<ev_check> watchers are invoked just after	1120	to gather new events, and all C<ev_check> watchers are invoked just after
1061	C<ev_loop> has gathered them, but before it invokes any callbacks for any	1121	C<ev_run> has gathered them, but before it invokes any callbacks for any
1062	received events. Callbacks of both watcher types can start and stop as	1122	received events. Callbacks of both watcher types can start and stop as
1063	many watchers as they want, and all of them will be taken into account	1123	many watchers as they want, and all of them will be taken into account
1064	(for example, a C<ev_prepare> watcher might start an idle watcher to keep	1124	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
1065	C<ev_loop> from blocking).	1125	C<ev_run> from blocking).
1066		1126
1067	=item C<EV_EMBED>	1127	=item C<EV_EMBED>
1068		1128
1069	The embedded event loop specified in the C<ev_embed> watcher needs attention.	1129	The embedded event loop specified in the C<ev_embed> watcher needs attention.
1070		1130
1071	=item C<EV_FORK>	1131	=item C<EV_FORK>
1072		1132
1073	The event loop has been resumed in the child process after fork (see	1133	The event loop has been resumed in the child process after fork (see
1074	C<ev_fork>).	1134	C<ev_fork>).
		1135
		1136	=item C<EV_CLEANUP>
		1137
		1138	The event loop is about to be destroyed (see C<ev_cleanup>).
1075		1139
1076	=item C<EV_ASYNC>	1140	=item C<EV_ASYNC>
1077		1141
1078	The given async watcher has been asynchronously notified (see C<ev_async>).	1142	The given async watcher has been asynchronously notified (see C<ev_async>).
1079		1143
…		…
1251		1315
1252	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related	1316	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related
1253	functions that do not need a watcher.	1317	functions that do not need a watcher.
1254		1318
1255	=back	1319	=back
1256
1257		1320
1258	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	1321	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
1259		1322
1260	Each watcher has, by default, a member C<void *data> that you can change	1323	Each watcher has, by default, a member C<void *data> that you can change
1261	and read at any time: libev will completely ignore it. This can be used	1324	and read at any time: libev will completely ignore it. This can be used
…		…
1317	t2_cb (EV_P_ ev_timer *w, int revents)	1380	t2_cb (EV_P_ ev_timer *w, int revents)
1318	{	1381	{
1319	struct my_biggy big = (struct my_biggy *)	1382	struct my_biggy big = (struct my_biggy *)
1320	(((char *)w) - offsetof (struct my_biggy, t2));	1383	(((char *)w) - offsetof (struct my_biggy, t2));
1321	}	1384	}
		1385
		1386	=head2 WATCHER STATES
		1387
		1388	There are various watcher states mentioned throughout this manual -
		1389	active, pending and so on. In this section these states and the rules to
		1390	transition between them will be described in more detail - and while these
		1391	rules might look complicated, they usually do "the right thing".
		1392
		1393	=over 4
		1394
		1395	=item initialiased
		1396
		1397	Before a watcher can be registered with the event looop it has to be
		1398	initialised. This can be done with a call to C<ev_TYPE_init>, or calls to
		1399	C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function.
		1400
		1401	In this state it is simply some block of memory that is suitable for use
		1402	in an event loop. It can be moved around, freed, reused etc. at will.
		1403
		1404	=item started/running/active
		1405
		1406	Once a watcher has been started with a call to C<ev_TYPE_start> it becomes
		1407	property of the event loop, and is actively waiting for events. While in
		1408	this state it cannot be accessed (except in a few documented ways), moved,
		1409	freed or anything else - the only legal thing is to keep a pointer to it,
		1410	and call libev functions on it that are documented to work on active watchers.
		1411
		1412	=item pending
		1413
		1414	If a watcher is active and libev determines that an event it is interested
		1415	in has occurred (such as a timer expiring), it will become pending. It will
		1416	stay in this pending state until either it is stopped or its callback is
		1417	about to be invoked, so it is not normally pending inside the watcher
		1418	callback.
		1419
		1420	The watcher might or might not be active while it is pending (for example,
		1421	an expired non-repeating timer can be pending but no longer active). If it
		1422	is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>),
		1423	but it is still property of the event loop at this time, so cannot be
		1424	moved, freed or reused. And if it is active the rules described in the
		1425	previous item still apply.
		1426
		1427	It is also possible to feed an event on a watcher that is not active (e.g.
		1428	via C<ev_feed_event>), in which case it becomes pending without being
		1429	active.
		1430
		1431	=item stopped
		1432
		1433	A watcher can be stopped implicitly by libev (in which case it might still
		1434	be pending), or explicitly by calling its C<ev_TYPE_stop> function. The
		1435	latter will clear any pending state the watcher might be in, regardless
		1436	of whether it was active or not, so stopping a watcher explicitly before
		1437	freeing it is often a good idea.
		1438
		1439	While stopped (and not pending) the watcher is essentially in the
		1440	initialised state, that is it can be reused, moved, modified in any way
		1441	you wish.
		1442
		1443	=back
1322		1444
1323	=head2 WATCHER PRIORITY MODELS	1445	=head2 WATCHER PRIORITY MODELS
1324		1446
1325	Many event loops support I<watcher priorities>, which are usually small	1447	Many event loops support I<watcher priorities>, which are usually small
1326	integers that influence the ordering of event callback invocation	1448	integers that influence the ordering of event callback invocation
…		…
1369		1491
1370	For example, to emulate how many other event libraries handle priorities,	1492	For example, to emulate how many other event libraries handle priorities,
1371	you can associate an C<ev_idle> watcher to each such watcher, and in	1493	you can associate an C<ev_idle> watcher to each such watcher, and in
1372	the normal watcher callback, you just start the idle watcher. The real	1494	the normal watcher callback, you just start the idle watcher. The real
1373	processing is done in the idle watcher callback. This causes libev to	1495	processing is done in the idle watcher callback. This causes libev to
1374	continously poll and process kernel event data for the watcher, but when	1496	continuously poll and process kernel event data for the watcher, but when
1375	the lock-out case is known to be rare (which in turn is rare :), this is	1497	the lock-out case is known to be rare (which in turn is rare :), this is
1376	workable.	1498	workable.
1377		1499
1378	Usually, however, the lock-out model implemented that way will perform	1500	Usually, however, the lock-out model implemented that way will perform
1379	miserably under the type of load it was designed to handle. In that case,	1501	miserably under the type of load it was designed to handle. In that case,
…		…
1393	{	1515	{
1394	// stop the I/O watcher, we received the event, but	1516	// stop the I/O watcher, we received the event, but
1395	// are not yet ready to handle it.	1517	// are not yet ready to handle it.
1396	ev_io_stop (EV_A_ w);	1518	ev_io_stop (EV_A_ w);
1397		1519
1398	// start the idle watcher to ahndle the actual event.	1520	// start the idle watcher to handle the actual event.
1399	// it will not be executed as long as other watchers	1521	// it will not be executed as long as other watchers
1400	// with the default priority are receiving events.	1522	// with the default priority are receiving events.
1401	ev_idle_start (EV_A_ &idle);	1523	ev_idle_start (EV_A_ &idle);
1402	}	1524	}
1403		1525
…		…
1457		1579
1458	If you cannot use non-blocking mode, then force the use of a	1580	If you cannot use non-blocking mode, then force the use of a
1459	known-to-be-good backend (at the time of this writing, this includes only	1581	known-to-be-good backend (at the time of this writing, this includes only
1460	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file	1582	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file
1461	descriptors for which non-blocking operation makes no sense (such as	1583	descriptors for which non-blocking operation makes no sense (such as
1462	files) - libev doesn't guarentee any specific behaviour in that case.	1584	files) - libev doesn't guarantee any specific behaviour in that case.
1463		1585
1464	Another thing you have to watch out for is that it is quite easy to	1586	Another thing you have to watch out for is that it is quite easy to
1465	receive "spurious" readiness notifications, that is your callback might	1587	receive "spurious" readiness notifications, that is your callback might
1466	be called with C<EV_READ> but a subsequent C<read>(2) will actually block	1588	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
1467	because there is no data. Not only are some backends known to create a	1589	because there is no data. Not only are some backends known to create a
…		…
1532		1654
1533	So when you encounter spurious, unexplained daemon exits, make sure you	1655	So when you encounter spurious, unexplained daemon exits, make sure you
1534	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon	1656	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon
1535	somewhere, as that would have given you a big clue).	1657	somewhere, as that would have given you a big clue).
1536		1658
		1659	=head3 The special problem of accept()ing when you can't
		1660
		1661	Many implementations of the POSIX C<accept> function (for example,
		1662	found in post-2004 Linux) have the peculiar behaviour of not removing a
		1663	connection from the pending queue in all error cases.
		1664
		1665	For example, larger servers often run out of file descriptors (because
		1666	of resource limits), causing C<accept> to fail with C<ENFILE> but not
		1667	rejecting the connection, leading to libev signalling readiness on
		1668	the next iteration again (the connection still exists after all), and
		1669	typically causing the program to loop at 100% CPU usage.
		1670
		1671	Unfortunately, the set of errors that cause this issue differs between
		1672	operating systems, there is usually little the app can do to remedy the
		1673	situation, and no known thread-safe method of removing the connection to
		1674	cope with overload is known (to me).
		1675
		1676	One of the easiest ways to handle this situation is to just ignore it
		1677	- when the program encounters an overload, it will just loop until the
		1678	situation is over. While this is a form of busy waiting, no OS offers an
		1679	event-based way to handle this situation, so it's the best one can do.
		1680
		1681	A better way to handle the situation is to log any errors other than
		1682	C<EAGAIN> and C<EWOULDBLOCK>, making sure not to flood the log with such
		1683	messages, and continue as usual, which at least gives the user an idea of
		1684	what could be wrong ("raise the ulimit!"). For extra points one could stop
		1685	the C<ev_io> watcher on the listening fd "for a while", which reduces CPU
		1686	usage.
		1687
		1688	If your program is single-threaded, then you could also keep a dummy file
		1689	descriptor for overload situations (e.g. by opening F</dev/null>), and
		1690	when you run into C<ENFILE> or C<EMFILE>, close it, run C<accept>,
		1691	close that fd, and create a new dummy fd. This will gracefully refuse
		1692	clients under typical overload conditions.
		1693
		1694	The last way to handle it is to simply log the error and C<exit>, as
		1695	is often done with C<malloc> failures, but this results in an easy
		1696	opportunity for a DoS attack.
1537		1697
1538	=head3 Watcher-Specific Functions	1698	=head3 Watcher-Specific Functions
1539		1699
1540	=over 4	1700	=over 4
1541		1701
…		…
1573	...	1733	...
1574	struct ev_loop *loop = ev_default_init (0);	1734	struct ev_loop *loop = ev_default_init (0);
1575	ev_io stdin_readable;	1735	ev_io stdin_readable;
1576	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1736	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1577	ev_io_start (loop, &stdin_readable);	1737	ev_io_start (loop, &stdin_readable);
1578	ev_loop (loop, 0);	1738	ev_run (loop, 0);
1579		1739
1580		1740
1581	=head2 C<ev_timer> - relative and optionally repeating timeouts	1741	=head2 C<ev_timer> - relative and optionally repeating timeouts
1582		1742
1583	Timer watchers are simple relative timers that generate an event after a	1743	Timer watchers are simple relative timers that generate an event after a
…		…
1592	The callback is guaranteed to be invoked only I<after> its timeout has	1752	The callback is guaranteed to be invoked only I<after> its timeout has
1593	passed (not I<at>, so on systems with very low-resolution clocks this	1753	passed (not I<at>, so on systems with very low-resolution clocks this
1594	might introduce a small delay). If multiple timers become ready during the	1754	might introduce a small delay). If multiple timers become ready during the
1595	same loop iteration then the ones with earlier time-out values are invoked	1755	same loop iteration then the ones with earlier time-out values are invoked
1596	before ones of the same priority with later time-out values (but this is	1756	before ones of the same priority with later time-out values (but this is
1597	no longer true when a callback calls C<ev_loop> recursively).	1757	no longer true when a callback calls C<ev_run> recursively).
1598		1758
1599	=head3 Be smart about timeouts	1759	=head3 Be smart about timeouts
1600		1760
1601	Many real-world problems involve some kind of timeout, usually for error	1761	Many real-world problems involve some kind of timeout, usually for error
1602	recovery. A typical example is an HTTP request - if the other side hangs,	1762	recovery. A typical example is an HTTP request - if the other side hangs,
…		…
1688	ev_tstamp timeout = last_activity + 60.;	1848	ev_tstamp timeout = last_activity + 60.;
1689		1849
1690	// if last_activity + 60. is older than now, we did time out	1850	// if last_activity + 60. is older than now, we did time out
1691	if (timeout < now)	1851	if (timeout < now)
1692	{	1852	{
1693	// timeout occured, take action	1853	// timeout occurred, take action
1694	}	1854	}
1695	else	1855	else
1696	{	1856	{
1697	// callback was invoked, but there was some activity, re-arm	1857	// callback was invoked, but there was some activity, re-arm
1698	// the watcher to fire in last_activity + 60, which is	1858	// the watcher to fire in last_activity + 60, which is
…		…
1720	to the current time (meaning we just have some activity :), then call the	1880	to the current time (meaning we just have some activity :), then call the
1721	callback, which will "do the right thing" and start the timer:	1881	callback, which will "do the right thing" and start the timer:
1722		1882
1723	ev_init (timer, callback);	1883	ev_init (timer, callback);
1724	last_activity = ev_now (loop);	1884	last_activity = ev_now (loop);
1725	callback (loop, timer, EV_TIMEOUT);	1885	callback (loop, timer, EV_TIMER);
1726		1886
1727	And when there is some activity, simply store the current time in	1887	And when there is some activity, simply store the current time in
1728	C<last_activity>, no libev calls at all:	1888	C<last_activity>, no libev calls at all:
1729		1889
1730	last_actiivty = ev_now (loop);	1890	last_activity = ev_now (loop);
1731		1891
1732	This technique is slightly more complex, but in most cases where the	1892	This technique is slightly more complex, but in most cases where the
1733	time-out is unlikely to be triggered, much more efficient.	1893	time-out is unlikely to be triggered, much more efficient.
1734		1894
1735	Changing the timeout is trivial as well (if it isn't hard-coded in the	1895	Changing the timeout is trivial as well (if it isn't hard-coded in the
…		…
1773		1933
1774	=head3 The special problem of time updates	1934	=head3 The special problem of time updates
1775		1935
1776	Establishing the current time is a costly operation (it usually takes at	1936	Establishing the current time is a costly operation (it usually takes at
1777	least two system calls): EV therefore updates its idea of the current	1937	least two system calls): EV therefore updates its idea of the current
1778	time only before and after C<ev_loop> collects new events, which causes a	1938	time only before and after C<ev_run> collects new events, which causes a
1779	growing difference between C<ev_now ()> and C<ev_time ()> when handling	1939	growing difference between C<ev_now ()> and C<ev_time ()> when handling
1780	lots of events in one iteration.	1940	lots of events in one iteration.
1781		1941
1782	The relative timeouts are calculated relative to the C<ev_now ()>	1942	The relative timeouts are calculated relative to the C<ev_now ()>
1783	time. This is usually the right thing as this timestamp refers to the time	1943	time. This is usually the right thing as this timestamp refers to the time
…		…
1861	Returns the remaining time until a timer fires. If the timer is active,	2021	Returns the remaining time until a timer fires. If the timer is active,
1862	then this time is relative to the current event loop time, otherwise it's	2022	then this time is relative to the current event loop time, otherwise it's
1863	the timeout value currently configured.	2023	the timeout value currently configured.
1864		2024
1865	That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns	2025	That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns
1866	C<5>. When the timer is started and one second passes, C<ev_timer_remain>	2026	C<5>. When the timer is started and one second passes, C<ev_timer_remaining>
1867	will return C<4>. When the timer expires and is restarted, it will return	2027	will return C<4>. When the timer expires and is restarted, it will return
1868	roughly C<7> (likely slightly less as callback invocation takes some time,	2028	roughly C<7> (likely slightly less as callback invocation takes some time,
1869	too), and so on.	2029	too), and so on.
1870		2030
1871	=item ev_tstamp repeat [read-write]	2031	=item ev_tstamp repeat [read-write]
…		…
1900	}	2060	}
1901		2061
1902	ev_timer mytimer;	2062	ev_timer mytimer;
1903	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	2063	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1904	ev_timer_again (&mytimer); /* start timer */	2064	ev_timer_again (&mytimer); /* start timer */
1905	ev_loop (loop, 0);	2065	ev_run (loop, 0);
1906		2066
1907	// and in some piece of code that gets executed on any "activity":	2067	// and in some piece of code that gets executed on any "activity":
1908	// reset the timeout to start ticking again at 10 seconds	2068	// reset the timeout to start ticking again at 10 seconds
1909	ev_timer_again (&mytimer);	2069	ev_timer_again (&mytimer);
1910		2070
…		…
1936		2096
1937	As with timers, the callback is guaranteed to be invoked only when the	2097	As with timers, the callback is guaranteed to be invoked only when the
1938	point in time where it is supposed to trigger has passed. If multiple	2098	point in time where it is supposed to trigger has passed. If multiple
1939	timers become ready during the same loop iteration then the ones with	2099	timers become ready during the same loop iteration then the ones with
1940	earlier time-out values are invoked before ones with later time-out values	2100	earlier time-out values are invoked before ones with later time-out values
1941	(but this is no longer true when a callback calls C<ev_loop> recursively).	2101	(but this is no longer true when a callback calls C<ev_run> recursively).
1942		2102
1943	=head3 Watcher-Specific Functions and Data Members	2103	=head3 Watcher-Specific Functions and Data Members
1944		2104
1945	=over 4	2105	=over 4
1946		2106
…		…
2074	Example: Call a callback every hour, or, more precisely, whenever the	2234	Example: Call a callback every hour, or, more precisely, whenever the
2075	system time is divisible by 3600. The callback invocation times have	2235	system time is divisible by 3600. The callback invocation times have
2076	potentially a lot of jitter, but good long-term stability.	2236	potentially a lot of jitter, but good long-term stability.
2077		2237
2078	static void	2238	static void
2079	clock_cb (struct ev_loop *loop, ev_io *w, int revents)	2239	clock_cb (struct ev_loop *loop, ev_periodic *w, int revents)
2080	{	2240	{
2081	... its now a full hour (UTC, or TAI or whatever your clock follows)	2241	... its now a full hour (UTC, or TAI or whatever your clock follows)
2082	}	2242	}
2083		2243
2084	ev_periodic hourly_tick;	2244	ev_periodic hourly_tick;
…		…
2107		2267
2108	=head2 C<ev_signal> - signal me when a signal gets signalled!	2268	=head2 C<ev_signal> - signal me when a signal gets signalled!
2109		2269
2110	Signal watchers will trigger an event when the process receives a specific	2270	Signal watchers will trigger an event when the process receives a specific
2111	signal one or more times. Even though signals are very asynchronous, libev	2271	signal one or more times. Even though signals are very asynchronous, libev
2112	will try it's best to deliver signals synchronously, i.e. as part of the	2272	will try its best to deliver signals synchronously, i.e. as part of the
2113	normal event processing, like any other event.	2273	normal event processing, like any other event.
2114		2274
2115	If you want signals to be delivered truly asynchronously, just use	2275	If you want signals to be delivered truly asynchronously, just use
2116	C<sigaction> as you would do without libev and forget about sharing	2276	C<sigaction> as you would do without libev and forget about sharing
2117	the signal. You can even use C<ev_async> from a signal handler to	2277	the signal. You can even use C<ev_async> from a signal handler to
…		…
2131	C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should	2291	C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should
2132	not be unduly interrupted. If you have a problem with system calls getting	2292	not be unduly interrupted. If you have a problem with system calls getting
2133	interrupted by signals you can block all signals in an C<ev_check> watcher	2293	interrupted by signals you can block all signals in an C<ev_check> watcher
2134	and unblock them in an C<ev_prepare> watcher.	2294	and unblock them in an C<ev_prepare> watcher.
2135		2295
2136	=head3 The special problem of inheritance over execve	2296	=head3 The special problem of inheritance over fork/execve/pthread_create
2137		2297
2138	Both the signal mask (C<sigprocmask>) and the signal disposition	2298	Both the signal mask (C<sigprocmask>) and the signal disposition
2139	(C<sigaction>) are unspecified after starting a signal watcher (and after	2299	(C<sigaction>) are unspecified after starting a signal watcher (and after
2140	stopping it again), that is, libev might or might not block the signal,	2300	stopping it again), that is, libev might or might not block the signal,
2141	and might or might not set or restore the installed signal handler.	2301	and might or might not set or restore the installed signal handler.
…		…
2151		2311
2152	The simplest way to ensure that the signal mask is reset in the child is	2312	The simplest way to ensure that the signal mask is reset in the child is
2153	to install a fork handler with C<pthread_atfork> that resets it. That will	2313	to install a fork handler with C<pthread_atfork> that resets it. That will
2154	catch fork calls done by libraries (such as the libc) as well.	2314	catch fork calls done by libraries (such as the libc) as well.
2155		2315
2156	In current versions of libev, you can also ensure that the signal mask is	2316	In current versions of libev, the signal will not be blocked indefinitely
2157	not blocking any signals (except temporarily, so thread users watch out)	2317	unless you use the C<signalfd> API (C<EV_SIGNALFD>). While this reduces
2158	by specifying the C<EVFLAG_NOSIGFD> when creating the event loop. This	2318	the window of opportunity for problems, it will not go away, as libev
2159	is not guaranteed for future versions, however.	2319	I<has> to modify the signal mask, at least temporarily.
		2320
		2321	So I can't stress this enough: I<If you do not reset your signal mask when
		2322	you expect it to be empty, you have a race condition in your code>. This
		2323	is not a libev-specific thing, this is true for most event libraries.
2160		2324
2161	=head3 Watcher-Specific Functions and Data Members	2325	=head3 Watcher-Specific Functions and Data Members
2162		2326
2163	=over 4	2327	=over 4
2164		2328
…		…
2180	Example: Try to exit cleanly on SIGINT.	2344	Example: Try to exit cleanly on SIGINT.
2181		2345
2182	static void	2346	static void
2183	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)	2347	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)
2184	{	2348	{
2185	ev_unloop (loop, EVUNLOOP_ALL);	2349	ev_break (loop, EVBREAK_ALL);
2186	}	2350	}
2187		2351
2188	ev_signal signal_watcher;	2352	ev_signal signal_watcher;
2189	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	2353	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
2190	ev_signal_start (loop, &signal_watcher);	2354	ev_signal_start (loop, &signal_watcher);
…		…
2576		2740
2577	Prepare and check watchers are usually (but not always) used in pairs:	2741	Prepare and check watchers are usually (but not always) used in pairs:
2578	prepare watchers get invoked before the process blocks and check watchers	2742	prepare watchers get invoked before the process blocks and check watchers
2579	afterwards.	2743	afterwards.
2580		2744
2581	You I<must not> call C<ev_loop> or similar functions that enter	2745	You I<must not> call C<ev_run> or similar functions that enter
2582	the current event loop from either C<ev_prepare> or C<ev_check>	2746	the current event loop from either C<ev_prepare> or C<ev_check>
2583	watchers. Other loops than the current one are fine, however. The	2747	watchers. Other loops than the current one are fine, however. The
2584	rationale behind this is that you do not need to check for recursion in	2748	rationale behind this is that you do not need to check for recursion in
2585	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,	2749	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,
2586	C<ev_check> so if you have one watcher of each kind they will always be	2750	C<ev_check> so if you have one watcher of each kind they will always be
…		…
2754		2918
2755	if (timeout >= 0)	2919	if (timeout >= 0)
2756	// create/start timer	2920	// create/start timer
2757		2921
2758	// poll	2922	// poll
2759	ev_loop (EV_A_ 0);	2923	ev_run (EV_A_ 0);
2760		2924
2761	// stop timer again	2925	// stop timer again
2762	if (timeout >= 0)	2926	if (timeout >= 0)
2763	ev_timer_stop (EV_A_ &to);	2927	ev_timer_stop (EV_A_ &to);
2764		2928
…		…
2842	if you do not want that, you need to temporarily stop the embed watcher).	3006	if you do not want that, you need to temporarily stop the embed watcher).
2843		3007
2844	=item ev_embed_sweep (loop, ev_embed *)	3008	=item ev_embed_sweep (loop, ev_embed *)
2845		3009
2846	Make a single, non-blocking sweep over the embedded loop. This works	3010	Make a single, non-blocking sweep over the embedded loop. This works
2847	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	3011	similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most
2848	appropriate way for embedded loops.	3012	appropriate way for embedded loops.
2849		3013
2850	=item struct ev_loop *other [read-only]	3014	=item struct ev_loop *other [read-only]
2851		3015
2852	The embedded event loop.	3016	The embedded event loop.
…		…
2912	C<ev_default_fork> cheats and calls it in the wrong process, the fork	3076	C<ev_default_fork> cheats and calls it in the wrong process, the fork
2913	handlers will be invoked, too, of course.	3077	handlers will be invoked, too, of course.
2914		3078
2915	=head3 The special problem of life after fork - how is it possible?	3079	=head3 The special problem of life after fork - how is it possible?
2916		3080
2917	Most uses of C<fork()> consist of forking, then some simple calls to ste	3081	Most uses of C<fork()> consist of forking, then some simple calls to set
2918	up/change the process environment, followed by a call to C<exec()>. This	3082	up/change the process environment, followed by a call to C<exec()>. This
2919	sequence should be handled by libev without any problems.	3083	sequence should be handled by libev without any problems.
2920		3084
2921	This changes when the application actually wants to do event handling	3085	This changes when the application actually wants to do event handling
2922	in the child, or both parent in child, in effect "continuing" after the	3086	in the child, or both parent in child, in effect "continuing" after the
…		…
2938	disadvantage of having to use multiple event loops (which do not support	3102	disadvantage of having to use multiple event loops (which do not support
2939	signal watchers).	3103	signal watchers).
2940		3104
2941	When this is not possible, or you want to use the default loop for	3105	When this is not possible, or you want to use the default loop for
2942	other reasons, then in the process that wants to start "fresh", call	3106	other reasons, then in the process that wants to start "fresh", call
2943	C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying	3107	C<ev_loop_destroy (EV_DEFAULT)> followed by C<ev_default_loop (...)>.
2944	the default loop will "orphan" (not stop) all registered watchers, so you	3108	Destroying the default loop will "orphan" (not stop) all registered
2945	have to be careful not to execute code that modifies those watchers. Note	3109	watchers, so you have to be careful not to execute code that modifies
2946	also that in that case, you have to re-register any signal watchers.	3110	those watchers. Note also that in that case, you have to re-register any
		3111	signal watchers.
2947		3112
2948	=head3 Watcher-Specific Functions and Data Members	3113	=head3 Watcher-Specific Functions and Data Members
2949		3114
2950	=over 4	3115	=over 4
2951		3116
2952	=item ev_fork_init (ev_signal *, callback)	3117	=item ev_fork_init (ev_fork *, callback)
2953		3118
2954	Initialises and configures the fork watcher - it has no parameters of any	3119	Initialises and configures the fork watcher - it has no parameters of any
2955	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,	3120	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
2956	believe me.	3121	really.
2957		3122
2958	=back	3123	=back
2959		3124
2960		3125
		3126	=head2 C<ev_cleanup> - even the best things end
		3127
		3128	Cleanup watchers are called just before the event loop is being destroyed
		3129	by a call to C<ev_loop_destroy>.
		3130
		3131	While there is no guarantee that the event loop gets destroyed, cleanup
		3132	watchers provide a convenient method to install cleanup hooks for your
		3133	program, worker threads and so on - you just to make sure to destroy the
		3134	loop when you want them to be invoked.
		3135
		3136	Cleanup watchers are invoked in the same way as any other watcher. Unlike
		3137	all other watchers, they do not keep a reference to the event loop (which
		3138	makes a lot of sense if you think about it). Like all other watchers, you
		3139	can call libev functions in the callback, except C<ev_cleanup_start>.
		3140
		3141	=head3 Watcher-Specific Functions and Data Members
		3142
		3143	=over 4
		3144
		3145	=item ev_cleanup_init (ev_cleanup *, callback)
		3146
		3147	Initialises and configures the cleanup watcher - it has no parameters of
		3148	any kind. There is a C<ev_cleanup_set> macro, but using it is utterly
		3149	pointless, I assure you.
		3150
		3151	=back
		3152
		3153	Example: Register an atexit handler to destroy the default loop, so any
		3154	cleanup functions are called.
		3155
		3156	static void
		3157	program_exits (void)
		3158	{
		3159	ev_loop_destroy (EV_DEFAULT_UC);
		3160	}
		3161
		3162	...
		3163	atexit (program_exits);
		3164
		3165
2961	=head2 C<ev_async> - how to wake up another event loop	3166	=head2 C<ev_async> - how to wake up an event loop
2962		3167
2963	In general, you cannot use an C<ev_loop> from multiple threads or other	3168	In general, you cannot use an C<ev_run> from multiple threads or other
2964	asynchronous sources such as signal handlers (as opposed to multiple event	3169	asynchronous sources such as signal handlers (as opposed to multiple event
2965	loops - those are of course safe to use in different threads).	3170	loops - those are of course safe to use in different threads).
2966		3171
2967	Sometimes, however, you need to wake up another event loop you do not	3172	Sometimes, however, you need to wake up an event loop you do not control,
2968	control, for example because it belongs to another thread. This is what	3173	for example because it belongs to another thread. This is what C<ev_async>
2969	C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you	3174	watchers do: as long as the C<ev_async> watcher is active, you can signal
2970	can signal it by calling C<ev_async_send>, which is thread- and signal	3175	it by calling C<ev_async_send>, which is thread- and signal safe.
2971	safe.
2972		3176
2973	This functionality is very similar to C<ev_signal> watchers, as signals,	3177	This functionality is very similar to C<ev_signal> watchers, as signals,
2974	too, are asynchronous in nature, and signals, too, will be compressed	3178	too, are asynchronous in nature, and signals, too, will be compressed
2975	(i.e. the number of callback invocations may be less than the number of	3179	(i.e. the number of callback invocations may be less than the number of
2976	C<ev_async_sent> calls).	3180	C<ev_async_sent> calls).
…		…
3131		3335
3132	If C<timeout> is less than 0, then no timeout watcher will be	3336	If C<timeout> is less than 0, then no timeout watcher will be
3133	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and	3337	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and
3134	repeat = 0) will be started. C<0> is a valid timeout.	3338	repeat = 0) will be started. C<0> is a valid timeout.
3135		3339
3136	The callback has the type C<void (*cb)(int revents, void *arg)> and gets	3340	The callback has the type C<void (*cb)(int revents, void *arg)> and is
3137	passed an C<revents> set like normal event callbacks (a combination of	3341	passed an C<revents> set like normal event callbacks (a combination of
3138	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>	3342	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMER>) and the C<arg>
3139	value passed to C<ev_once>. Note that it is possible to receive I<both>	3343	value passed to C<ev_once>. Note that it is possible to receive I<both>
3140	a timeout and an io event at the same time - you probably should give io	3344	a timeout and an io event at the same time - you probably should give io
3141	events precedence.	3345	events precedence.
3142		3346
3143	Example: wait up to ten seconds for data to appear on STDIN_FILENO.	3347	Example: wait up to ten seconds for data to appear on STDIN_FILENO.
3144		3348
3145	static void stdin_ready (int revents, void *arg)	3349	static void stdin_ready (int revents, void *arg)
3146	{	3350	{
3147	if (revents & EV_READ)	3351	if (revents & EV_READ)
3148	/* stdin might have data for us, joy! */;	3352	/* stdin might have data for us, joy! */;
3149	else if (revents & EV_TIMEOUT)	3353	else if (revents & EV_TIMER)
3150	/* doh, nothing entered */;	3354	/* doh, nothing entered */;
3151	}	3355	}
3152		3356
3153	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	3357	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
3154		3358
…		…
3163	loop!).	3367	loop!).
3164		3368
3165	=back	3369	=back
3166		3370
3167		3371
		3372	=head1 COMMON OR USEFUL IDIOMS (OR BOTH)
		3373
		3374	This section explains some common idioms that are not immediately
		3375	obvious. Note that examples are sprinkled over the whole manual, and this
		3376	section only contains stuff that wouldn't fit anywhere else.
		3377
		3378	=over 4
		3379
		3380	=item Model/nested event loop invocations and exit conditions.
		3381
		3382	Often (especially in GUI toolkits) there are places where you have
		3383	I<modal> interaction, which is most easily implemented by recursively
		3384	invoking C<ev_run>.
		3385
		3386	This brings the problem of exiting - a callback might want to finish the
		3387	main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but
		3388	a modal "Are you sure?" dialog is still waiting), or just the nested one
		3389	and not the main one (e.g. user clocked "Ok" in a modal dialog), or some
		3390	other combination: In these cases, C<ev_break> will not work alone.
		3391
		3392	The solution is to maintain "break this loop" variable for each C<ev_run>
		3393	invocation, and use a loop around C<ev_run> until the condition is
		3394	triggered, using C<EVRUN_ONCE>:
		3395
		3396	// main loop
		3397	int exit_main_loop = 0;
		3398
		3399	while (!exit_main_loop)
		3400	ev_run (EV_DEFAULT_ EVRUN_ONCE);
		3401
		3402	// in a model watcher
		3403	int exit_nested_loop = 0;
		3404
		3405	while (!exit_nested_loop)
		3406	ev_run (EV_A_ EVRUN_ONCE);
		3407
		3408	To exit from any of these loops, just set the corresponding exit variable:
		3409
		3410	// exit modal loop
		3411	exit_nested_loop = 1;
		3412
		3413	// exit main program, after modal loop is finished
		3414	exit_main_loop = 1;
		3415
		3416	// exit both
		3417	exit_main_loop = exit_nested_loop = 1;
		3418
		3419	=back
		3420
		3421
3168	=head1 LIBEVENT EMULATION	3422	=head1 LIBEVENT EMULATION
3169		3423
3170	Libev offers a compatibility emulation layer for libevent. It cannot	3424	Libev offers a compatibility emulation layer for libevent. It cannot
3171	emulate the internals of libevent, so here are some usage hints:	3425	emulate the internals of libevent, so here are some usage hints:
3172		3426
3173	=over 4	3427	=over 4
		3428
		3429	=item * Only the libevent-1.4.1-beta API is being emulated.
		3430
		3431	This was the newest libevent version available when libev was implemented,
		3432	and is still mostly unchanged in 2010.
3174		3433
3175	=item * Use it by including <event.h>, as usual.	3434	=item * Use it by including <event.h>, as usual.
3176		3435
3177	=item * The following members are fully supported: ev_base, ev_callback,	3436	=item * The following members are fully supported: ev_base, ev_callback,
3178	ev_arg, ev_fd, ev_res, ev_events.	3437	ev_arg, ev_fd, ev_res, ev_events.
…		…
3184	=item * Priorities are not currently supported. Initialising priorities	3443	=item * Priorities are not currently supported. Initialising priorities
3185	will fail and all watchers will have the same priority, even though there	3444	will fail and all watchers will have the same priority, even though there
3186	is an ev_pri field.	3445	is an ev_pri field.
3187		3446
3188	=item * In libevent, the last base created gets the signals, in libev, the	3447	=item * In libevent, the last base created gets the signals, in libev, the
3189	first base created (== the default loop) gets the signals.	3448	base that registered the signal gets the signals.
3190		3449
3191	=item * Other members are not supported.	3450	=item * Other members are not supported.
3192		3451
3193	=item * The libev emulation is I<not> ABI compatible to libevent, you need	3452	=item * The libev emulation is I<not> ABI compatible to libevent, you need
3194	to use the libev header file and library.	3453	to use the libev header file and library.
…		…
3213	Care has been taken to keep the overhead low. The only data member the C++	3472	Care has been taken to keep the overhead low. The only data member the C++
3214	classes add (compared to plain C-style watchers) is the event loop pointer	3473	classes add (compared to plain C-style watchers) is the event loop pointer
3215	that the watcher is associated with (or no additional members at all if	3474	that the watcher is associated with (or no additional members at all if
3216	you disable C<EV_MULTIPLICITY> when embedding libev).	3475	you disable C<EV_MULTIPLICITY> when embedding libev).
3217		3476
3218	Currently, functions, and static and non-static member functions can be	3477	Currently, functions, static and non-static member functions and classes
3219	used as callbacks. Other types should be easy to add as long as they only	3478	with C<operator ()> can be used as callbacks. Other types should be easy
3220	need one additional pointer for context. If you need support for other	3479	to add as long as they only need one additional pointer for context. If
3221	types of functors please contact the author (preferably after implementing	3480	you need support for other types of functors please contact the author
3222	it).	3481	(preferably after implementing it).
3223		3482
3224	Here is a list of things available in the C<ev> namespace:	3483	Here is a list of things available in the C<ev> namespace:
3225		3484
3226	=over 4	3485	=over 4
3227		3486
…		…
3288	myclass obj;	3547	myclass obj;
3289	ev::io iow;	3548	ev::io iow;
3290	iow.set <myclass, &myclass::io_cb> (&obj);	3549	iow.set <myclass, &myclass::io_cb> (&obj);
3291		3550
3292	=item w->set (object *)	3551	=item w->set (object *)
3293
3294	This is an B<experimental> feature that might go away in a future version.
3295		3552
3296	This is a variation of a method callback - leaving out the method to call	3553	This is a variation of a method callback - leaving out the method to call
3297	will default the method to C<operator ()>, which makes it possible to use	3554	will default the method to C<operator ()>, which makes it possible to use
3298	functor objects without having to manually specify the C<operator ()> all	3555	functor objects without having to manually specify the C<operator ()> all
3299	the time. Incidentally, you can then also leave out the template argument	3556	the time. Incidentally, you can then also leave out the template argument
…		…
3339	Associates a different C<struct ev_loop> with this watcher. You can only	3596	Associates a different C<struct ev_loop> with this watcher. You can only
3340	do this when the watcher is inactive (and not pending either).	3597	do this when the watcher is inactive (and not pending either).
3341		3598
3342	=item w->set ([arguments])	3599	=item w->set ([arguments])
3343		3600
3344	Basically the same as C<ev_TYPE_set>, with the same arguments. Must be	3601	Basically the same as C<ev_TYPE_set>, with the same arguments. Either this
3345	called at least once. Unlike the C counterpart, an active watcher gets	3602	method or a suitable start method must be called at least once. Unlike the
3346	automatically stopped and restarted when reconfiguring it with this	3603	C counterpart, an active watcher gets automatically stopped and restarted
3347	method.	3604	when reconfiguring it with this method.
3348		3605
3349	=item w->start ()	3606	=item w->start ()
3350		3607
3351	Starts the watcher. Note that there is no C<loop> argument, as the	3608	Starts the watcher. Note that there is no C<loop> argument, as the
3352	constructor already stores the event loop.	3609	constructor already stores the event loop.
3353		3610
		3611	=item w->start ([arguments])
		3612
		3613	Instead of calling C<set> and C<start> methods separately, it is often
		3614	convenient to wrap them in one call. Uses the same type of arguments as
		3615	the configure C<set> method of the watcher.
		3616
3354	=item w->stop ()	3617	=item w->stop ()
3355		3618
3356	Stops the watcher if it is active. Again, no C<loop> argument.	3619	Stops the watcher if it is active. Again, no C<loop> argument.
3357		3620
3358	=item w->again () (C<ev::timer>, C<ev::periodic> only)	3621	=item w->again () (C<ev::timer>, C<ev::periodic> only)
…		…
3370		3633
3371	=back	3634	=back
3372		3635
3373	=back	3636	=back
3374		3637
3375	Example: Define a class with an IO and idle watcher, start one of them in	3638	Example: Define a class with two I/O and idle watchers, start the I/O
3376	the constructor.	3639	watchers in the constructor.
3377		3640
3378	class myclass	3641	class myclass
3379	{	3642	{
3380	ev::io io ; void io_cb (ev::io &w, int revents);	3643	ev::io io ; void io_cb (ev::io &w, int revents);
		3644	ev::io2 io2 ; void io2_cb (ev::io &w, int revents);
3381	ev::idle idle; void idle_cb (ev::idle &w, int revents);	3645	ev::idle idle; void idle_cb (ev::idle &w, int revents);
3382		3646
3383	myclass (int fd)	3647	myclass (int fd)
3384	{	3648	{
3385	io .set <myclass, &myclass::io_cb > (this);	3649	io .set <myclass, &myclass::io_cb > (this);
		3650	io2 .set <myclass, &myclass::io2_cb > (this);
3386	idle.set <myclass, &myclass::idle_cb> (this);	3651	idle.set <myclass, &myclass::idle_cb> (this);
3387		3652
3388	io.start (fd, ev::READ);	3653	io.set (fd, ev::WRITE); // configure the watcher
		3654	io.start (); // start it whenever convenient
		3655
		3656	io2.start (fd, ev::READ); // set + start in one call
3389	}	3657	}
3390	};	3658	};
3391		3659
3392		3660
3393	=head1 OTHER LANGUAGE BINDINGS	3661	=head1 OTHER LANGUAGE BINDINGS
…		…
3441	Erkki Seppala has written Ocaml bindings for libev, to be found at	3709	Erkki Seppala has written Ocaml bindings for libev, to be found at
3442	L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>.	3710	L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>.
3443		3711
3444	=item Lua	3712	=item Lua
3445		3713
3446	Brian Maher has written a partial interface to libev	3714	Brian Maher has written a partial interface to libev for lua (at the
3447	for lua (only C<ev_io> and C<ev_timer>), to be found at	3715	time of this writing, only C<ev_io> and C<ev_timer>), to be found at
3448	L<http://github.com/brimworks/lua-ev>.	3716	L<http://github.com/brimworks/lua-ev>.
3449		3717
3450	=back	3718	=back
3451		3719
3452		3720
…		…
3467	loop argument"). The C<EV_A> form is used when this is the sole argument,	3735	loop argument"). The C<EV_A> form is used when this is the sole argument,
3468	C<EV_A_> is used when other arguments are following. Example:	3736	C<EV_A_> is used when other arguments are following. Example:
3469		3737
3470	ev_unref (EV_A);	3738	ev_unref (EV_A);
3471	ev_timer_add (EV_A_ watcher);	3739	ev_timer_add (EV_A_ watcher);
3472	ev_loop (EV_A_ 0);	3740	ev_run (EV_A_ 0);
3473		3741
3474	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	3742	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
3475	which is often provided by the following macro.	3743	which is often provided by the following macro.
3476		3744
3477	=item C<EV_P>, C<EV_P_>	3745	=item C<EV_P>, C<EV_P_>
…		…
3517	}	3785	}
3518		3786
3519	ev_check check;	3787	ev_check check;
3520	ev_check_init (&check, check_cb);	3788	ev_check_init (&check, check_cb);
3521	ev_check_start (EV_DEFAULT_ &check);	3789	ev_check_start (EV_DEFAULT_ &check);
3522	ev_loop (EV_DEFAULT_ 0);	3790	ev_run (EV_DEFAULT_ 0);
3523		3791
3524	=head1 EMBEDDING	3792	=head1 EMBEDDING
3525		3793
3526	Libev can (and often is) directly embedded into host	3794	Libev can (and often is) directly embedded into host
3527	applications. Examples of applications that embed it include the Deliantra	3795	applications. Examples of applications that embed it include the Deliantra
…		…
3607	libev.m4	3875	libev.m4
3608		3876
3609	=head2 PREPROCESSOR SYMBOLS/MACROS	3877	=head2 PREPROCESSOR SYMBOLS/MACROS
3610		3878
3611	Libev can be configured via a variety of preprocessor symbols you have to	3879	Libev can be configured via a variety of preprocessor symbols you have to
3612	define before including any of its files. The default in the absence of	3880	define before including (or compiling) any of its files. The default in
3613	autoconf is documented for every option.	3881	the absence of autoconf is documented for every option.
		3882
		3883	Symbols marked with "(h)" do not change the ABI, and can have different
		3884	values when compiling libev vs. including F<ev.h>, so it is permissible
		3885	to redefine them before including F<ev.h> without breaking compatibility
		3886	to a compiled library. All other symbols change the ABI, which means all
		3887	users of libev and the libev code itself must be compiled with compatible
		3888	settings.
3614		3889
3615	=over 4	3890	=over 4
3616		3891
		3892	=item EV_COMPAT3 (h)
		3893
		3894	Backwards compatibility is a major concern for libev. This is why this
		3895	release of libev comes with wrappers for the functions and symbols that
		3896	have been renamed between libev version 3 and 4.
		3897
		3898	You can disable these wrappers (to test compatibility with future
		3899	versions) by defining C<EV_COMPAT3> to C<0> when compiling your
		3900	sources. This has the additional advantage that you can drop the C<struct>
		3901	from C<struct ev_loop> declarations, as libev will provide an C<ev_loop>
		3902	typedef in that case.
		3903
		3904	In some future version, the default for C<EV_COMPAT3> will become C<0>,
		3905	and in some even more future version the compatibility code will be
		3906	removed completely.
		3907
3617	=item EV_STANDALONE	3908	=item EV_STANDALONE (h)
3618		3909
3619	Must always be C<1> if you do not use autoconf configuration, which	3910	Must always be C<1> if you do not use autoconf configuration, which
3620	keeps libev from including F<config.h>, and it also defines dummy	3911	keeps libev from including F<config.h>, and it also defines dummy
3621	implementations for some libevent functions (such as logging, which is not	3912	implementations for some libevent functions (such as logging, which is not
3622	supported). It will also not define any of the structs usually found in	3913	supported). It will also not define any of the structs usually found in
…		…
3772	as well as for signal and thread safety in C<ev_async> watchers.	4063	as well as for signal and thread safety in C<ev_async> watchers.
3773		4064
3774	In the absence of this define, libev will use C<sig_atomic_t volatile>	4065	In the absence of this define, libev will use C<sig_atomic_t volatile>
3775	(from F<signal.h>), which is usually good enough on most platforms.	4066	(from F<signal.h>), which is usually good enough on most platforms.
3776		4067
3777	=item EV_H	4068	=item EV_H (h)
3778		4069
3779	The name of the F<ev.h> header file used to include it. The default if	4070	The name of the F<ev.h> header file used to include it. The default if
3780	undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be	4071	undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be
3781	used to virtually rename the F<ev.h> header file in case of conflicts.	4072	used to virtually rename the F<ev.h> header file in case of conflicts.
3782		4073
3783	=item EV_CONFIG_H	4074	=item EV_CONFIG_H (h)
3784		4075
3785	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override	4076	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override
3786	F<ev.c>'s idea of where to find the F<config.h> file, similarly to	4077	F<ev.c>'s idea of where to find the F<config.h> file, similarly to
3787	C<EV_H>, above.	4078	C<EV_H>, above.
3788		4079
3789	=item EV_EVENT_H	4080	=item EV_EVENT_H (h)
3790		4081
3791	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea	4082	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea
3792	of how the F<event.h> header can be found, the default is C<"event.h">.	4083	of how the F<event.h> header can be found, the default is C<"event.h">.
3793		4084
3794	=item EV_PROTOTYPES	4085	=item EV_PROTOTYPES (h)
3795		4086
3796	If defined to be C<0>, then F<ev.h> will not define any function	4087	If defined to be C<0>, then F<ev.h> will not define any function
3797	prototypes, but still define all the structs and other symbols. This is	4088	prototypes, but still define all the structs and other symbols. This is
3798	occasionally useful if you want to provide your own wrapper functions	4089	occasionally useful if you want to provide your own wrapper functions
3799	around libev functions.	4090	around libev functions.
…		…
3821	fine.	4112	fine.
3822		4113
3823	If your embedding application does not need any priorities, defining these	4114	If your embedding application does not need any priorities, defining these
3824	both to C<0> will save some memory and CPU.	4115	both to C<0> will save some memory and CPU.
3825		4116
3826	=item EV_PERIODIC_ENABLE	4117	=item EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE,
		4118	EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE,
		4119	EV_ASYNC_ENABLE, EV_CHILD_ENABLE.
3827		4120
3828	If undefined or defined to be C<1>, then periodic timers are supported. If	4121	If undefined or defined to be C<1> (and the platform supports it), then
3829	defined to be C<0>, then they are not. Disabling them saves a few kB of	4122	the respective watcher type is supported. If defined to be C<0>, then it
3830	code.	4123	is not. Disabling watcher types mainly saves code size.
3831		4124
3832	=item EV_IDLE_ENABLE	4125	=item EV_FEATURES
3833
3834	If undefined or defined to be C<1>, then idle watchers are supported. If
3835	defined to be C<0>, then they are not. Disabling them saves a few kB of
3836	code.
3837
3838	=item EV_EMBED_ENABLE
3839
3840	If undefined or defined to be C<1>, then embed watchers are supported. If
3841	defined to be C<0>, then they are not. Embed watchers rely on most other
3842	watcher types, which therefore must not be disabled.
3843
3844	=item EV_STAT_ENABLE
3845
3846	If undefined or defined to be C<1>, then stat watchers are supported. If
3847	defined to be C<0>, then they are not.
3848
3849	=item EV_FORK_ENABLE
3850
3851	If undefined or defined to be C<1>, then fork watchers are supported. If
3852	defined to be C<0>, then they are not.
3853
3854	=item EV_ASYNC_ENABLE
3855
3856	If undefined or defined to be C<1>, then async watchers are supported. If
3857	defined to be C<0>, then they are not.
3858
3859	=item EV_MINIMAL
3860		4126
3861	If you need to shave off some kilobytes of code at the expense of some	4127	If you need to shave off some kilobytes of code at the expense of some
3862	speed (but with the full API), define this symbol to C<1>. Currently this	4128	speed (but with the full API), you can define this symbol to request
3863	is used to override some inlining decisions, saves roughly 30% code size	4129	certain subsets of functionality. The default is to enable all features
3864	on amd64. It also selects a much smaller 2-heap for timer management over	4130	that can be enabled on the platform.
3865	the default 4-heap.
3866		4131
3867	You can save even more by disabling watcher types you do not need	4132	A typical way to use this symbol is to define it to C<0> (or to a bitset
3868	and setting C<EV_MAXPRI> == C<EV_MINPRI>. Also, disabling C<assert>	4133	with some broad features you want) and then selectively re-enable
3869	(C<-DNDEBUG>) will usually reduce code size a lot.	4134	additional parts you want, for example if you want everything minimal,
		4135	but multiple event loop support, async and child watchers and the poll
		4136	backend, use this:
3870		4137
3871	Defining C<EV_MINIMAL> to C<2> will additionally reduce the core API to	4138	#define EV_FEATURES 0
3872	provide a bare-bones event library. See C<ev.h> for details on what parts	4139	#define EV_MULTIPLICITY 1
3873	of the API are still available, and do not complain if this subset changes	4140	#define EV_USE_POLL 1
3874	over time.	4141	#define EV_CHILD_ENABLE 1
		4142	#define EV_ASYNC_ENABLE 1
		4143
		4144	The actual value is a bitset, it can be a combination of the following
		4145	values:
		4146
		4147	=over 4
		4148
		4149	=item C<1> - faster/larger code
		4150
		4151	Use larger code to speed up some operations.
		4152
		4153	Currently this is used to override some inlining decisions (enlarging the
		4154	code size by roughly 30% on amd64).
		4155
		4156	When optimising for size, use of compiler flags such as C<-Os> with
		4157	gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of
		4158	assertions.
		4159
		4160	=item C<2> - faster/larger data structures
		4161
		4162	Replaces the small 2-heap for timer management by a faster 4-heap, larger
		4163	hash table sizes and so on. This will usually further increase code size
		4164	and can additionally have an effect on the size of data structures at
		4165	runtime.
		4166
		4167	=item C<4> - full API configuration
		4168
		4169	This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and
		4170	enables multiplicity (C<EV_MULTIPLICITY>=1).
		4171
		4172	=item C<8> - full API
		4173
		4174	This enables a lot of the "lesser used" API functions. See C<ev.h> for
		4175	details on which parts of the API are still available without this
		4176	feature, and do not complain if this subset changes over time.
		4177
		4178	=item C<16> - enable all optional watcher types
		4179
		4180	Enables all optional watcher types. If you want to selectively enable
		4181	only some watcher types other than I/O and timers (e.g. prepare,
		4182	embed, async, child...) you can enable them manually by defining
		4183	C<EV_watchertype_ENABLE> to C<1> instead.
		4184
		4185	=item C<32> - enable all backends
		4186
		4187	This enables all backends - without this feature, you need to enable at
		4188	least one backend manually (C<EV_USE_SELECT> is a good choice).
		4189
		4190	=item C<64> - enable OS-specific "helper" APIs
		4191
		4192	Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by
		4193	default.
		4194
		4195	=back
		4196
		4197	Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0>
		4198	reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb
		4199	code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O
		4200	watchers, timers and monotonic clock support.
		4201
		4202	With an intelligent-enough linker (gcc+binutils are intelligent enough
		4203	when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by
		4204	your program might be left out as well - a binary starting a timer and an
		4205	I/O watcher then might come out at only 5Kb.
		4206
		4207	=item EV_AVOID_STDIO
		4208
		4209	If this is set to C<1> at compiletime, then libev will avoid using stdio
		4210	functions (printf, scanf, perror etc.). This will increase the code size
		4211	somewhat, but if your program doesn't otherwise depend on stdio and your
		4212	libc allows it, this avoids linking in the stdio library which is quite
		4213	big.
		4214
		4215	Note that error messages might become less precise when this option is
		4216	enabled.
3875		4217
3876	=item EV_NSIG	4218	=item EV_NSIG
3877		4219
3878	The highest supported signal number, +1 (or, the number of	4220	The highest supported signal number, +1 (or, the number of
3879	signals): Normally, libev tries to deduce the maximum number of signals	4221	signals): Normally, libev tries to deduce the maximum number of signals
3880	automatically, but sometimes this fails, in which case it can be	4222	automatically, but sometimes this fails, in which case it can be
3881	specified. Also, using a lower number than detected (C<32> should be	4223	specified. Also, using a lower number than detected (C<32> should be
3882	good for about any system in existance) can save some memory, as libev	4224	good for about any system in existence) can save some memory, as libev
3883	statically allocates some 12-24 bytes per signal number.	4225	statically allocates some 12-24 bytes per signal number.
3884		4226
3885	=item EV_PID_HASHSIZE	4227	=item EV_PID_HASHSIZE
3886		4228
3887	C<ev_child> watchers use a small hash table to distribute workload by	4229	C<ev_child> watchers use a small hash table to distribute workload by
3888	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more	4230	pid. The default size is C<16> (or C<1> with C<EV_FEATURES> disabled),
3889	than enough. If you need to manage thousands of children you might want to	4231	usually more than enough. If you need to manage thousands of children you
3890	increase this value (I<must> be a power of two).	4232	might want to increase this value (I<must> be a power of two).
3891		4233
3892	=item EV_INOTIFY_HASHSIZE	4234	=item EV_INOTIFY_HASHSIZE
3893		4235
3894	C<ev_stat> watchers use a small hash table to distribute workload by	4236	C<ev_stat> watchers use a small hash table to distribute workload by
3895	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),	4237	inotify watch id. The default size is C<16> (or C<1> with C<EV_FEATURES>
3896	usually more than enough. If you need to manage thousands of C<ev_stat>	4238	disabled), usually more than enough. If you need to manage thousands of
3897	watchers you might want to increase this value (I<must> be a power of	4239	C<ev_stat> watchers you might want to increase this value (I<must> be a
3898	two).	4240	power of two).
3899		4241
3900	=item EV_USE_4HEAP	4242	=item EV_USE_4HEAP
3901		4243
3902	Heaps are not very cache-efficient. To improve the cache-efficiency of the	4244	Heaps are not very cache-efficient. To improve the cache-efficiency of the
3903	timer and periodics heaps, libev uses a 4-heap when this symbol is defined	4245	timer and periodics heaps, libev uses a 4-heap when this symbol is defined
3904	to C<1>. The 4-heap uses more complicated (longer) code but has noticeably	4246	to C<1>. The 4-heap uses more complicated (longer) code but has noticeably
3905	faster performance with many (thousands) of watchers.	4247	faster performance with many (thousands) of watchers.
3906		4248
3907	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>	4249	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3908	(disabled).	4250	will be C<0>.
3909		4251
3910	=item EV_HEAP_CACHE_AT	4252	=item EV_HEAP_CACHE_AT
3911		4253
3912	Heaps are not very cache-efficient. To improve the cache-efficiency of the	4254	Heaps are not very cache-efficient. To improve the cache-efficiency of the
3913	timer and periodics heaps, libev can cache the timestamp (I<at>) within	4255	timer and periodics heaps, libev can cache the timestamp (I<at>) within
3914	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),	4256	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),
3915	which uses 8-12 bytes more per watcher and a few hundred bytes more code,	4257	which uses 8-12 bytes more per watcher and a few hundred bytes more code,
3916	but avoids random read accesses on heap changes. This improves performance	4258	but avoids random read accesses on heap changes. This improves performance
3917	noticeably with many (hundreds) of watchers.	4259	noticeably with many (hundreds) of watchers.
3918		4260
3919	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>	4261	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3920	(disabled).	4262	will be C<0>.
3921		4263
3922	=item EV_VERIFY	4264	=item EV_VERIFY
3923		4265
3924	Controls how much internal verification (see C<ev_loop_verify ()>) will	4266	Controls how much internal verification (see C<ev_verify ()>) will
3925	be done: If set to C<0>, no internal verification code will be compiled	4267	be done: If set to C<0>, no internal verification code will be compiled
3926	in. If set to C<1>, then verification code will be compiled in, but not	4268	in. If set to C<1>, then verification code will be compiled in, but not
3927	called. If set to C<2>, then the internal verification code will be	4269	called. If set to C<2>, then the internal verification code will be
3928	called once per loop, which can slow down libev. If set to C<3>, then the	4270	called once per loop, which can slow down libev. If set to C<3>, then the
3929	verification code will be called very frequently, which will slow down	4271	verification code will be called very frequently, which will slow down
3930	libev considerably.	4272	libev considerably.
3931		4273
3932	The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be	4274	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3933	C<0>.	4275	will be C<0>.
3934		4276
3935	=item EV_COMMON	4277	=item EV_COMMON
3936		4278
3937	By default, all watchers have a C<void *data> member. By redefining	4279	By default, all watchers have a C<void *data> member. By redefining
3938	this macro to a something else you can include more and other types of	4280	this macro to something else you can include more and other types of
3939	members. You have to define it each time you include one of the files,	4281	members. You have to define it each time you include one of the files,
3940	though, and it must be identical each time.	4282	though, and it must be identical each time.
3941		4283
3942	For example, the perl EV module uses something like this:	4284	For example, the perl EV module uses something like this:
3943		4285
…		…
3996	file.	4338	file.
3997		4339
3998	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	4340	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
3999	that everybody includes and which overrides some configure choices:	4341	that everybody includes and which overrides some configure choices:
4000		4342
4001	#define EV_MINIMAL 1	4343	#define EV_FEATURES 8
4002	#define EV_USE_POLL 0	4344	#define EV_USE_SELECT 1
4003	#define EV_MULTIPLICITY 0
4004	#define EV_PERIODIC_ENABLE 0	4345	#define EV_PREPARE_ENABLE 1
		4346	#define EV_IDLE_ENABLE 1
4005	#define EV_STAT_ENABLE 0	4347	#define EV_SIGNAL_ENABLE 1
4006	#define EV_FORK_ENABLE 0	4348	#define EV_CHILD_ENABLE 1
		4349	#define EV_USE_STDEXCEPT 0
4007	#define EV_CONFIG_H <config.h>	4350	#define EV_CONFIG_H <config.h>
4008	#define EV_MINPRI 0
4009	#define EV_MAXPRI 0
4010		4351
4011	#include "ev++.h"	4352	#include "ev++.h"
4012		4353
4013	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	4354	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
4014		4355
…		…
4145	userdata *u = ev_userdata (EV_A);	4486	userdata *u = ev_userdata (EV_A);
4146	pthread_mutex_lock (&u->lock);	4487	pthread_mutex_lock (&u->lock);
4147	}	4488	}
4148		4489
4149	The event loop thread first acquires the mutex, and then jumps straight	4490	The event loop thread first acquires the mutex, and then jumps straight
4150	into C<ev_loop>:	4491	into C<ev_run>:
4151		4492
4152	void *	4493	void *
4153	l_run (void *thr_arg)	4494	l_run (void *thr_arg)
4154	{	4495	{
4155	struct ev_loop *loop = (struct ev_loop *)thr_arg;	4496	struct ev_loop *loop = (struct ev_loop *)thr_arg;
4156		4497
4157	l_acquire (EV_A);	4498	l_acquire (EV_A);
4158	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);	4499	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
4159	ev_loop (EV_A_ 0);	4500	ev_run (EV_A_ 0);
4160	l_release (EV_A);	4501	l_release (EV_A);
4161		4502
4162	return 0;	4503	return 0;
4163	}	4504	}
4164		4505
…		…
4216		4557
4217	=head3 COROUTINES	4558	=head3 COROUTINES
4218		4559
4219	Libev is very accommodating to coroutines ("cooperative threads"):	4560	Libev is very accommodating to coroutines ("cooperative threads"):
4220	libev fully supports nesting calls to its functions from different	4561	libev fully supports nesting calls to its functions from different
4221	coroutines (e.g. you can call C<ev_loop> on the same loop from two	4562	coroutines (e.g. you can call C<ev_run> on the same loop from two
4222	different coroutines, and switch freely between both coroutines running	4563	different coroutines, and switch freely between both coroutines running
4223	the loop, as long as you don't confuse yourself). The only exception is	4564	the loop, as long as you don't confuse yourself). The only exception is
4224	that you must not do this from C<ev_periodic> reschedule callbacks.	4565	that you must not do this from C<ev_periodic> reschedule callbacks.
4225		4566
4226	Care has been taken to ensure that libev does not keep local state inside	4567	Care has been taken to ensure that libev does not keep local state inside
4227	C<ev_loop>, and other calls do not usually allow for coroutine switches as	4568	C<ev_run>, and other calls do not usually allow for coroutine switches as
4228	they do not call any callbacks.	4569	they do not call any callbacks.
4229		4570
4230	=head2 COMPILER WARNINGS	4571	=head2 COMPILER WARNINGS
4231		4572
4232	Depending on your compiler and compiler settings, you might get no or a	4573	Depending on your compiler and compiler settings, you might get no or a
…		…
4243	maintainable.	4584	maintainable.
4244		4585
4245	And of course, some compiler warnings are just plain stupid, or simply	4586	And of course, some compiler warnings are just plain stupid, or simply
4246	wrong (because they don't actually warn about the condition their message	4587	wrong (because they don't actually warn about the condition their message
4247	seems to warn about). For example, certain older gcc versions had some	4588	seems to warn about). For example, certain older gcc versions had some
4248	warnings that resulted an extreme number of false positives. These have	4589	warnings that resulted in an extreme number of false positives. These have
4249	been fixed, but some people still insist on making code warn-free with	4590	been fixed, but some people still insist on making code warn-free with
4250	such buggy versions.	4591	such buggy versions.
4251		4592
4252	While libev is written to generate as few warnings as possible,	4593	While libev is written to generate as few warnings as possible,
4253	"warn-free" code is not a goal, and it is recommended not to build libev	4594	"warn-free" code is not a goal, and it is recommended not to build libev
…		…
4289	I suggest using suppression lists.	4630	I suggest using suppression lists.
4290		4631
4291		4632
4292	=head1 PORTABILITY NOTES	4633	=head1 PORTABILITY NOTES
4293		4634
		4635	=head2 GNU/LINUX 32 BIT LIMITATIONS
		4636
		4637	GNU/Linux is the only common platform that supports 64 bit file/large file
		4638	interfaces but I<disables> them by default.
		4639
		4640	That means that libev compiled in the default environment doesn't support
		4641	files larger than 2GiB or so, which mainly affects C<ev_stat> watchers.
		4642
		4643	Unfortunately, many programs try to work around this GNU/Linux issue
		4644	by enabling the large file API, which makes them incompatible with the
		4645	standard libev compiled for their system.
		4646
		4647	Likewise, libev cannot enable the large file API itself as this would
		4648	suddenly make it incompatible to the default compile time environment,
		4649	i.e. all programs not using special compile switches.
		4650
		4651	=head2 OS/X AND DARWIN BUGS
		4652
		4653	The whole thing is a bug if you ask me - basically any system interface
		4654	you touch is broken, whether it is locales, poll, kqueue or even the
		4655	OpenGL drivers.
		4656
		4657	=head3 C<kqueue> is buggy
		4658
		4659	The kqueue syscall is broken in all known versions - most versions support
		4660	only sockets, many support pipes.
		4661
		4662	Libev tries to work around this by not using C<kqueue> by default on this
		4663	rotten platform, but of course you can still ask for it when creating a
		4664	loop - embedding a socket-only kqueue loop into a select-based one is
		4665	probably going to work well.
		4666
		4667	=head3 C<poll> is buggy
		4668
		4669	Instead of fixing C<kqueue>, Apple replaced their (working) C<poll>
		4670	implementation by something calling C<kqueue> internally around the 10.5.6
		4671	release, so now C<kqueue> I<and> C<poll> are broken.
		4672
		4673	Libev tries to work around this by not using C<poll> by default on
		4674	this rotten platform, but of course you can still ask for it when creating
		4675	a loop.
		4676
		4677	=head3 C<select> is buggy
		4678
		4679	All that's left is C<select>, and of course Apple found a way to fuck this
		4680	one up as well: On OS/X, C<select> actively limits the number of file
		4681	descriptors you can pass in to 1024 - your program suddenly crashes when
		4682	you use more.
		4683
		4684	There is an undocumented "workaround" for this - defining
		4685	C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should>
		4686	work on OS/X.
		4687
		4688	=head2 SOLARIS PROBLEMS AND WORKAROUNDS
		4689
		4690	=head3 C<errno> reentrancy
		4691
		4692	The default compile environment on Solaris is unfortunately so
		4693	thread-unsafe that you can't even use components/libraries compiled
		4694	without C<-D_REENTRANT> in a threaded program, which, of course, isn't
		4695	defined by default. A valid, if stupid, implementation choice.
		4696
		4697	If you want to use libev in threaded environments you have to make sure
		4698	it's compiled with C<_REENTRANT> defined.
		4699
		4700	=head3 Event port backend
		4701
		4702	The scalable event interface for Solaris is called "event
		4703	ports". Unfortunately, this mechanism is very buggy in all major
		4704	releases. If you run into high CPU usage, your program freezes or you get
		4705	a large number of spurious wakeups, make sure you have all the relevant
		4706	and latest kernel patches applied. No, I don't know which ones, but there
		4707	are multiple ones to apply, and afterwards, event ports actually work
		4708	great.
		4709
		4710	If you can't get it to work, you can try running the program by setting
		4711	the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and
		4712	C<select> backends.
		4713
		4714	=head2 AIX POLL BUG
		4715
		4716	AIX unfortunately has a broken C<poll.h> header. Libev works around
		4717	this by trying to avoid the poll backend altogether (i.e. it's not even
		4718	compiled in), which normally isn't a big problem as C<select> works fine
		4719	with large bitsets on AIX, and AIX is dead anyway.
		4720
4294	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS	4721	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
		4722
		4723	=head3 General issues
4295		4724
4296	Win32 doesn't support any of the standards (e.g. POSIX) that libev	4725	Win32 doesn't support any of the standards (e.g. POSIX) that libev
4297	requires, and its I/O model is fundamentally incompatible with the POSIX	4726	requires, and its I/O model is fundamentally incompatible with the POSIX
4298	model. Libev still offers limited functionality on this platform in	4727	model. Libev still offers limited functionality on this platform in
4299	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	4728	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
4300	descriptors. This only applies when using Win32 natively, not when using	4729	descriptors. This only applies when using Win32 natively, not when using
4301	e.g. cygwin.	4730	e.g. cygwin. Actually, it only applies to the microsofts own compilers,
		4731	as every compielr comes with a slightly differently broken/incompatible
		4732	environment.
4302		4733
4303	Lifting these limitations would basically require the full	4734	Lifting these limitations would basically require the full
4304	re-implementation of the I/O system. If you are into these kinds of	4735	re-implementation of the I/O system. If you are into this kind of thing,
4305	things, then note that glib does exactly that for you in a very portable	4736	then note that glib does exactly that for you in a very portable way (note
4306	way (note also that glib is the slowest event library known to man).	4737	also that glib is the slowest event library known to man).
4307		4738
4308	There is no supported compilation method available on windows except	4739	There is no supported compilation method available on windows except
4309	embedding it into other applications.	4740	embedding it into other applications.
4310		4741
4311	Sensible signal handling is officially unsupported by Microsoft - libev	4742	Sensible signal handling is officially unsupported by Microsoft - libev
…		…
4339	you do I<not> compile the F<ev.c> or any other embedded source files!):	4770	you do I<not> compile the F<ev.c> or any other embedded source files!):
4340		4771
4341	#include "evwrap.h"	4772	#include "evwrap.h"
4342	#include "ev.c"	4773	#include "ev.c"
4343		4774
4344	=over 4
4345
4346	=item The winsocket select function	4775	=head3 The winsocket C<select> function
4347		4776
4348	The winsocket C<select> function doesn't follow POSIX in that it	4777	The winsocket C<select> function doesn't follow POSIX in that it
4349	requires socket I<handles> and not socket I<file descriptors> (it is	4778	requires socket I<handles> and not socket I<file descriptors> (it is
4350	also extremely buggy). This makes select very inefficient, and also	4779	also extremely buggy). This makes select very inefficient, and also
4351	requires a mapping from file descriptors to socket handles (the Microsoft	4780	requires a mapping from file descriptors to socket handles (the Microsoft
…		…
4360	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */	4789	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
4361		4790
4362	Note that winsockets handling of fd sets is O(n), so you can easily get a	4791	Note that winsockets handling of fd sets is O(n), so you can easily get a
4363	complexity in the O(n²) range when using win32.	4792	complexity in the O(n²) range when using win32.
4364		4793
4365	=item Limited number of file descriptors	4794	=head3 Limited number of file descriptors
4366		4795
4367	Windows has numerous arbitrary (and low) limits on things.	4796	Windows has numerous arbitrary (and low) limits on things.
4368		4797
4369	Early versions of winsocket's select only supported waiting for a maximum	4798	Early versions of winsocket's select only supported waiting for a maximum
4370	of C<64> handles (probably owning to the fact that all windows kernels	4799	of C<64> handles (probably owning to the fact that all windows kernels
…		…
4385	runtime libraries. This might get you to about C<512> or C<2048> sockets	4814	runtime libraries. This might get you to about C<512> or C<2048> sockets
4386	(depending on windows version and/or the phase of the moon). To get more,	4815	(depending on windows version and/or the phase of the moon). To get more,
4387	you need to wrap all I/O functions and provide your own fd management, but	4816	you need to wrap all I/O functions and provide your own fd management, but
4388	the cost of calling select (O(n²)) will likely make this unworkable.	4817	the cost of calling select (O(n²)) will likely make this unworkable.
4389		4818
4390	=back
4391
4392	=head2 PORTABILITY REQUIREMENTS	4819	=head2 PORTABILITY REQUIREMENTS
4393		4820
4394	In addition to a working ISO-C implementation and of course the	4821	In addition to a working ISO-C implementation and of course the
4395	backend-specific APIs, libev relies on a few additional extensions:	4822	backend-specific APIs, libev relies on a few additional extensions:
4396		4823
…		…
4402	Libev assumes not only that all watcher pointers have the same internal	4829	Libev assumes not only that all watcher pointers have the same internal
4403	structure (guaranteed by POSIX but not by ISO C for example), but it also	4830	structure (guaranteed by POSIX but not by ISO C for example), but it also
4404	assumes that the same (machine) code can be used to call any watcher	4831	assumes that the same (machine) code can be used to call any watcher
4405	callback: The watcher callbacks have different type signatures, but libev	4832	callback: The watcher callbacks have different type signatures, but libev
4406	calls them using an C<ev_watcher *> internally.	4833	calls them using an C<ev_watcher *> internally.
		4834
		4835	=item pointer accesses must be thread-atomic
		4836
		4837	Accessing a pointer value must be atomic, it must both be readable and
		4838	writable in one piece - this is the case on all current architectures.
4407		4839
4408	=item C<sig_atomic_t volatile> must be thread-atomic as well	4840	=item C<sig_atomic_t volatile> must be thread-atomic as well
4409		4841
4410	The type C<sig_atomic_t volatile> (or whatever is defined as	4842	The type C<sig_atomic_t volatile> (or whatever is defined as
4411	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different	4843	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different
…		…
4434	watchers.	4866	watchers.
4435		4867
4436	=item C<double> must hold a time value in seconds with enough accuracy	4868	=item C<double> must hold a time value in seconds with enough accuracy
4437		4869
4438	The type C<double> is used to represent timestamps. It is required to	4870	The type C<double> is used to represent timestamps. It is required to
4439	have at least 51 bits of mantissa (and 9 bits of exponent), which is good	4871	have at least 51 bits of mantissa (and 9 bits of exponent), which is
4440	enough for at least into the year 4000. This requirement is fulfilled by	4872	good enough for at least into the year 4000 with millisecond accuracy
		4873	(the design goal for libev). This requirement is overfulfilled by
4441	implementations implementing IEEE 754, which is basically all existing	4874	implementations using IEEE 754, which is basically all existing ones. With
4442	ones. With IEEE 754 doubles, you get microsecond accuracy until at least	4875	IEEE 754 doubles, you get microsecond accuracy until at least 2200.
4443	2200.
4444		4876
4445	=back	4877	=back
4446		4878
4447	If you know of other additional requirements drop me a note.	4879	If you know of other additional requirements drop me a note.
4448		4880
…		…
4516	involves iterating over all running async watchers or all signal numbers.	4948	involves iterating over all running async watchers or all signal numbers.
4517		4949
4518	=back	4950	=back
4519		4951
4520		4952
		4953	=head1 PORTING FROM LIBEV 3.X TO 4.X
		4954
		4955	The major version 4 introduced some incompatible changes to the API.
		4956
		4957	At the moment, the C<ev.h> header file provides compatibility definitions
		4958	for all changes, so most programs should still compile. The compatibility
		4959	layer might be removed in later versions of libev, so better update to the
		4960	new API early than late.
		4961
		4962	=over 4
		4963
		4964	=item C<EV_COMPAT3> backwards compatibility mechanism
		4965
		4966	The backward compatibility mechanism can be controlled by
		4967	C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING>
		4968	section.
		4969
		4970	=item C<ev_default_destroy> and C<ev_default_fork> have been removed
		4971
		4972	These calls can be replaced easily by their C<ev_loop_xxx> counterparts:
		4973
		4974	ev_loop_destroy (EV_DEFAULT_UC);
		4975	ev_loop_fork (EV_DEFAULT);
		4976
		4977	=item function/symbol renames
		4978
		4979	A number of functions and symbols have been renamed:
		4980
		4981	ev_loop => ev_run
		4982	EVLOOP_NONBLOCK => EVRUN_NOWAIT
		4983	EVLOOP_ONESHOT => EVRUN_ONCE
		4984
		4985	ev_unloop => ev_break
		4986	EVUNLOOP_CANCEL => EVBREAK_CANCEL
		4987	EVUNLOOP_ONE => EVBREAK_ONE
		4988	EVUNLOOP_ALL => EVBREAK_ALL
		4989
		4990	EV_TIMEOUT => EV_TIMER
		4991
		4992	ev_loop_count => ev_iteration
		4993	ev_loop_depth => ev_depth
		4994	ev_loop_verify => ev_verify
		4995
		4996	Most functions working on C<struct ev_loop> objects don't have an
		4997	C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and
		4998	associated constants have been renamed to not collide with the C<struct
		4999	ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme
		5000	as all other watcher types. Note that C<ev_loop_fork> is still called
		5001	C<ev_loop_fork> because it would otherwise clash with the C<ev_fork>
		5002	typedef.
		5003
		5004	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>
		5005
		5006	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different
		5007	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile
		5008	and work, but the library code will of course be larger.
		5009
		5010	=back
		5011
		5012
4521	=head1 GLOSSARY	5013	=head1 GLOSSARY
4522		5014
4523	=over 4	5015	=over 4
4524		5016
4525	=item active	5017	=item active
4526		5018
4527	A watcher is active as long as it has been started (has been attached to	5019	A watcher is active as long as it has been started and not yet stopped.
4528	an event loop) but not yet stopped (disassociated from the event loop).	5020	See L<WATCHER STATES> for details.
4529		5021
4530	=item application	5022	=item application
4531		5023
4532	In this document, an application is whatever is using libev.	5024	In this document, an application is whatever is using libev.
		5025
		5026	=item backend
		5027
		5028	The part of the code dealing with the operating system interfaces.
4533		5029
4534	=item callback	5030	=item callback
4535		5031
4536	The address of a function that is called when some event has been	5032	The address of a function that is called when some event has been
4537	detected. Callbacks are being passed the event loop, the watcher that	5033	detected. Callbacks are being passed the event loop, the watcher that
4538	received the event, and the actual event bitset.	5034	received the event, and the actual event bitset.
4539		5035
4540	=item callback invocation	5036	=item callback/watcher invocation
4541		5037
4542	The act of calling the callback associated with a watcher.	5038	The act of calling the callback associated with a watcher.
4543		5039
4544	=item event	5040	=item event
4545		5041
4546	A change of state of some external event, such as data now being available	5042	A change of state of some external event, such as data now being available
4547	for reading on a file descriptor, time having passed or simply not having	5043	for reading on a file descriptor, time having passed or simply not having
4548	any other events happening anymore.	5044	any other events happening anymore.
4549		5045
4550	In libev, events are represented as single bits (such as C<EV_READ> or	5046	In libev, events are represented as single bits (such as C<EV_READ> or
4551	C<EV_TIMEOUT>).	5047	C<EV_TIMER>).
4552		5048
4553	=item event library	5049	=item event library
4554		5050
4555	A software package implementing an event model and loop.	5051	A software package implementing an event model and loop.
4556		5052
…		…
4564	The model used to describe how an event loop handles and processes	5060	The model used to describe how an event loop handles and processes
4565	watchers and events.	5061	watchers and events.
4566		5062
4567	=item pending	5063	=item pending
4568		5064
4569	A watcher is pending as soon as the corresponding event has been detected,	5065	A watcher is pending as soon as the corresponding event has been
4570	and stops being pending as soon as the watcher will be invoked or its	5066	detected. See L<WATCHER STATES> for details.
4571	pending status is explicitly cleared by the application.
4572
4573	A watcher can be pending, but not active. Stopping a watcher also clears
4574	its pending status.
4575		5067
4576	=item real time	5068	=item real time
4577		5069
4578	The physical time that is observed. It is apparently strictly monotonic :)	5070	The physical time that is observed. It is apparently strictly monotonic :)
4579		5071
…		…
4586	=item watcher	5078	=item watcher
4587		5079
4588	A data structure that describes interest in certain events. Watchers need	5080	A data structure that describes interest in certain events. Watchers need
4589	to be started (attached to an event loop) before they can receive events.	5081	to be started (attached to an event loop) before they can receive events.
4590		5082
4591	=item watcher invocation
4592
4593	The act of calling the callback associated with a watcher.
4594
4595	=back	5083	=back
4596		5084
4597	=head1 AUTHOR	5085	=head1 AUTHOR
4598		5086
4599	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson.	5087	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael
		5088	Magnusson and Emanuele Giaquinta.
4600		5089

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