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Revision 1.277 by root, Thu Dec 31 06:50:17 2009 UTC vs.
Revision 1.341 by root, Fri Nov 5 22:08:09 2010 UTC

…		…
26	puts ("stdin ready");	26	puts ("stdin ready");
27	// for one-shot events, one must manually stop the watcher	27	// for one-shot events, one must manually stop the watcher
28	// with its corresponding stop function.	28	// with its corresponding stop function.
29	ev_io_stop (EV_A_ w);	29	ev_io_stop (EV_A_ w);
30		30
31	// this causes all nested ev_loop's to stop iterating	31	// this causes all nested ev_run's to stop iterating
32	ev_unloop (EV_A_ EVUNLOOP_ALL);	32	ev_break (EV_A_ EVBREAK_ALL);
33	}	33	}
34		34
35	// another callback, this time for a time-out	35	// another callback, this time for a time-out
36	static void	36	static void
37	timeout_cb (EV_P_ ev_timer *w, int revents)	37	timeout_cb (EV_P_ ev_timer *w, int revents)
38	{	38	{
39	puts ("timeout");	39	puts ("timeout");
40	// this causes the innermost ev_loop to stop iterating	40	// this causes the innermost ev_run to stop iterating
41	ev_unloop (EV_A_ EVUNLOOP_ONE);	41	ev_break (EV_A_ EVBREAK_ONE);
42	}	42	}
43		43
44	int	44	int
45	main (void)	45	main (void)
46	{	46	{
47	// use the default event loop unless you have special needs	47	// use the default event loop unless you have special needs
48	struct ev_loop *loop = ev_default_loop (0);	48	struct ev_loop *loop = EV_DEFAULT;
49		49
50	// initialise an io watcher, then start it	50	// initialise an io watcher, then start it
51	// this one will watch for stdin to become readable	51	// this one will watch for stdin to become readable
52	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);	52	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);
53	ev_io_start (loop, &stdin_watcher);	53	ev_io_start (loop, &stdin_watcher);
…		…
56	// simple non-repeating 5.5 second timeout	56	// simple non-repeating 5.5 second timeout
57	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);	57	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
58	ev_timer_start (loop, &timeout_watcher);	58	ev_timer_start (loop, &timeout_watcher);
59		59
60	// now wait for events to arrive	60	// now wait for events to arrive
61	ev_loop (loop, 0);	61	ev_run (loop, 0);
62		62
63	// unloop was called, so exit	63	// unloop was called, so exit
64	return 0;	64	return 0;
65	}	65	}
66		66
…		…
75	While this document tries to be as complete as possible in documenting	75	While this document tries to be as complete as possible in documenting
76	libev, its usage and the rationale behind its design, it is not a tutorial	76	libev, its usage and the rationale behind its design, it is not a tutorial
77	on event-based programming, nor will it introduce event-based programming	77	on event-based programming, nor will it introduce event-based programming
78	with libev.	78	with libev.
79		79
80	Familarity with event based programming techniques in general is assumed	80	Familiarity with event based programming techniques in general is assumed
81	throughout this document.	81	throughout this document.
		82
		83	=head1 WHAT TO READ WHEN IN A HURRY
		84
		85	This manual tries to be very detailed, but unfortunately, this also makes
		86	it very long. If you just want to know the basics of libev, I suggest
		87	reading L<ANATOMY OF A WATCHER>, then the L<EXAMPLE PROGRAM> above and
		88	look up the missing functions in L<GLOBAL FUNCTIONS> and the C<ev_io> and
		89	C<ev_timer> sections in L<WATCHER TYPES>.
82		90
83	=head1 ABOUT LIBEV	91	=head1 ABOUT LIBEV
84		92
85	Libev is an event loop: you register interest in certain events (such as a	93	Libev is an event loop: you register interest in certain events (such as a
86	file descriptor being readable or a timeout occurring), and it will manage	94	file descriptor being readable or a timeout occurring), and it will manage
…		…
124	this argument.	132	this argument.
125		133
126	=head2 TIME REPRESENTATION	134	=head2 TIME REPRESENTATION
127		135
128	Libev represents time as a single floating point number, representing	136	Libev represents time as a single floating point number, representing
129	the (fractional) number of seconds since the (POSIX) epoch (somewhere	137	the (fractional) number of seconds since the (POSIX) epoch (in practice
130	near the beginning of 1970, details are complicated, don't ask). This	138	somewhere near the beginning of 1970, details are complicated, don't
131	type is called C<ev_tstamp>, which is what you should use too. It usually	139	ask). This type is called C<ev_tstamp>, which is what you should use
132	aliases to the C<double> type in C. When you need to do any calculations	140	too. It usually aliases to the C<double> type in C. When you need to do
133	on it, you should treat it as some floating point value. Unlike the name	141	any calculations on it, you should treat it as some floating point value.
		142
134	component C<stamp> might indicate, it is also used for time differences	143	Unlike the name component C<stamp> might indicate, it is also used for
135	throughout libev.	144	time differences (e.g. delays) throughout libev.
136		145
137	=head1 ERROR HANDLING	146	=head1 ERROR HANDLING
138		147
139	Libev knows three classes of errors: operating system errors, usage errors	148	Libev knows three classes of errors: operating system errors, usage errors
140	and internal errors (bugs).	149	and internal errors (bugs).
…		…
164		173
165	=item ev_tstamp ev_time ()	174	=item ev_tstamp ev_time ()
166		175
167	Returns the current time as libev would use it. Please note that the	176	Returns the current time as libev would use it. Please note that the
168	C<ev_now> function is usually faster and also often returns the timestamp	177	C<ev_now> function is usually faster and also often returns the timestamp
169	you actually want to know.	178	you actually want to know. Also interesting is the combination of
		179	C<ev_update_now> and C<ev_now>.
170		180
171	=item ev_sleep (ev_tstamp interval)	181	=item ev_sleep (ev_tstamp interval)
172		182
173	Sleep for the given interval: The current thread will be blocked until	183	Sleep for the given interval: The current thread will be blocked until
174	either it is interrupted or the given time interval has passed. Basically	184	either it is interrupted or the given time interval has passed. Basically
…		…
191	as this indicates an incompatible change. Minor versions are usually	201	as this indicates an incompatible change. Minor versions are usually
192	compatible to older versions, so a larger minor version alone is usually	202	compatible to older versions, so a larger minor version alone is usually
193	not a problem.	203	not a problem.
194		204
195	Example: Make sure we haven't accidentally been linked against the wrong	205	Example: Make sure we haven't accidentally been linked against the wrong
196	version.	206	version (note, however, that this will not detect other ABI mismatches,
		207	such as LFS or reentrancy).
197		208
198	assert (("libev version mismatch",	209	assert (("libev version mismatch",
199	ev_version_major () == EV_VERSION_MAJOR	210	ev_version_major () == EV_VERSION_MAJOR
200	&& ev_version_minor () >= EV_VERSION_MINOR));	211	&& ev_version_minor () >= EV_VERSION_MINOR));
201		212
…		…
212	assert (("sorry, no epoll, no sex",	223	assert (("sorry, no epoll, no sex",
213	ev_supported_backends () & EVBACKEND_EPOLL));	224	ev_supported_backends () & EVBACKEND_EPOLL));
214		225
215	=item unsigned int ev_recommended_backends ()	226	=item unsigned int ev_recommended_backends ()
216		227
217	Return the set of all backends compiled into this binary of libev and also	228	Return the set of all backends compiled into this binary of libev and
218	recommended for this platform. This set is often smaller than the one	229	also recommended for this platform, meaning it will work for most file
		230	descriptor types. This set is often smaller than the one returned by
219	returned by C<ev_supported_backends>, as for example kqueue is broken on	231	C<ev_supported_backends>, as for example kqueue is broken on most BSDs
220	most BSDs and will not be auto-detected unless you explicitly request it	232	and will not be auto-detected unless you explicitly request it (assuming
221	(assuming you know what you are doing). This is the set of backends that	233	you know what you are doing). This is the set of backends that libev will
222	libev will probe for if you specify no backends explicitly.	234	probe for if you specify no backends explicitly.
223		235
224	=item unsigned int ev_embeddable_backends ()	236	=item unsigned int ev_embeddable_backends ()
225		237
226	Returns the set of backends that are embeddable in other event loops. This	238	Returns the set of backends that are embeddable in other event loops. This
227	is the theoretical, all-platform, value. To find which backends	239	value is platform-specific but can include backends not available on the
228	might be supported on the current system, you would need to look at	240	current system. To find which embeddable backends might be supported on
229	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for	241	the current system, you would need to look at C<ev_embeddable_backends ()
230	recommended ones.	242	& ev_supported_backends ()>, likewise for recommended ones.
231		243
232	See the description of C<ev_embed> watchers for more info.	244	See the description of C<ev_embed> watchers for more info.
233		245
234	=item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT]	246	=item ev_set_allocator (void *(*cb)(void *ptr, long size))
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	Note that this function I<is> thread-safe, and one common way to use
		361	libev with threads is indeed to create one loop per thread, and using the
		362	default loop in the "main" or "initial" thread.
326		363
327	The flags argument can be used to specify special behaviour or specific	364	The flags argument can be used to specify special behaviour or specific
328	backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>).	365	backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>).
329		366
330	The following flags are supported:	367	The following flags are supported:
…		…
345	useful to try out specific backends to test their performance, or to work	382	useful to try out specific backends to test their performance, or to work
346	around bugs.	383	around bugs.
347		384
348	=item C<EVFLAG_FORKCHECK>	385	=item C<EVFLAG_FORKCHECK>
349		386
350	Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after	387	Instead of calling C<ev_loop_fork> manually after a fork, you can also
351	a fork, you can also make libev check for a fork in each iteration by	388	make libev check for a fork in each iteration by enabling this flag.
352	enabling this flag.
353		389
354	This works by calling C<getpid ()> on every iteration of the loop,	390	This works by calling C<getpid ()> on every iteration of the loop,
355	and thus this might slow down your event loop if you do a lot of loop	391	and thus this might slow down your event loop if you do a lot of loop
356	iterations and little real work, but is usually not noticeable (on my	392	iterations and little real work, but is usually not noticeable (on my
357	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence	393	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence
…		…
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_SIGNALFD>	411	=item C<EVFLAG_SIGNALFD>
376		412
377	When this flag is specified, then libev will 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 API	414	I<signalfd> API for its C<ev_signal> (and C<ev_child>) watchers. This API
379	delivers signals synchronously, which makes is both faster and might make	415	delivers signals synchronously, which makes it both faster and might make
380	it possible to get the queued signal data.	416	it possible to get the queued signal data. It can also simplify signal
		417	handling with threads, as long as you properly block signals in your
		418	threads that are not interested in handling them.
381		419
382	Signalfd will not be used by default as this changes your signal mask, and	420	Signalfd will not be used by default as this changes your signal mask, and
383	there are a lot of shoddy libraries and programs (glib's threadpool for	421	there are a lot of shoddy libraries and programs (glib's threadpool for
384	example) that can't properly initialise their signal masks.	422	example) that can't properly initialise their signal masks.
385		423
…		…
425	epoll scales either O(1) or O(active_fds).	463	epoll scales either O(1) or O(active_fds).
426		464
427	The epoll mechanism deserves honorable mention as the most misdesigned	465	The epoll mechanism deserves honorable mention as the most misdesigned
428	of the more advanced event mechanisms: mere annoyances include silently	466	of the more advanced event mechanisms: mere annoyances include silently
429	dropping file descriptors, requiring a system call per change per file	467	dropping file descriptors, requiring a system call per change per file
430	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
431	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
432	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
433	take considerable time (one syscall per file descriptor) and is of course	473	set, which can take considerable time (one syscall per file descriptor)
434	hard to detect.	474	and is of course hard to detect.
435		475
436	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
437	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
438	I<different> file descriptors (even already closed ones, so one cannot	478	I<different> file descriptors (even already closed ones, so one cannot
439	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
440	on SMP systems). Libev tries to counter these spurious notifications by	480	on SMP systems). Libev tries to counter these spurious notifications by
441	employing an additional generation counter and comparing that against the	481	employing an additional generation counter and comparing that against the
442	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.
443		487
444	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
445	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
446	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
447	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
…		…
545	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,
546	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
547	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
548	()> will be tried.	592	()> will be tried.
549		593
550	Example: This is the most typical usage.
551
552	if (!ev_default_loop (0))
553	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
554
555	Example: Restrict libev to the select and poll backends, and do not allow
556	environment settings to be taken into account:
557
558	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
559
560	Example: Use whatever libev has to offer, but make sure that kqueue is
561	used if available (warning, breaks stuff, best use only with your own
562	private event loop and only if you know the OS supports your types of
563	fds):
564
565	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
566
567	=item struct ev_loop *ev_loop_new (unsigned int flags)
568
569	Similar to C<ev_default_loop>, but always creates a new event loop that is
570	always distinct from the default loop. Unlike the default loop, it cannot
571	handle signal and child watchers, and attempts to do so will be greeted by
572	undefined behaviour (or a failed assertion if assertions are enabled).
573
574	Note that this function I<is> thread-safe, and the recommended way to use
575	libev with threads is indeed to create one loop per thread, and using the
576	default loop in the "main" or "initial" thread.
577
578	Example: Try to create a event loop that uses epoll and nothing else.	594	Example: Try to create a event loop that uses epoll and nothing else.
579		595
580	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	596	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
581	if (!epoller)	597	if (!epoller)
582	fatal ("no epoll found here, maybe it hides under your chair");	598	fatal ("no epoll found here, maybe it hides under your chair");
583		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
584	=item ev_default_destroy ()	605	=item ev_loop_destroy (loop)
585		606
586	Destroys the default loop again (frees all memory and kernel state	607	Destroys an event loop object (frees all memory and kernel state
587	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
588	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
589	responsibility to either stop all watchers cleanly yourself I<before>	610	responsibility to either stop all watchers cleanly yourself I<before>
590	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
591	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
…		…
593		614
594	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
595	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
596	as signal and child watchers) would need to be stopped manually.	617	as signal and child watchers) would need to be stopped manually.
597		618
598	In general it is not advisable to call this function except in the	619	This function is normally used on loop objects allocated by
599	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.
600	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>
601	C<ev_loop_new> and C<ev_loop_destroy>.	626	and C<ev_loop_destroy>.
602		627
603	=item ev_loop_destroy (loop)	628	=item ev_loop_fork (loop)
604		629
605	Like C<ev_default_destroy>, but destroys an event loop created by an
606	earlier call to C<ev_loop_new>.
607
608	=item ev_default_fork ()
609
610	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
611	to reinitialise the kernel state for backends that have one. Despite the	631	reinitialise the kernel state for backends that have one. Despite the
612	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
613	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
614	sense). You I<must> call it in the child before using any of the libev	634	child before resuming or calling C<ev_run>.
615	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.
616		640
617	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
618	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
619	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).
620		647
621	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
622	it just in case after a fork. To make this easy, the function will fit in	649	it just in case after a fork.
623	quite nicely into a call to C<pthread_atfork>:
624		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	...
625	pthread_atfork (0, 0, ev_default_fork);	661	pthread_atfork (0, 0, post_fork_child);
626
627	=item ev_loop_fork (loop)
628
629	Like C<ev_default_fork>, but acts on an event loop created by
630	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
631	after fork that you want to re-use in the child, and how you do this is
632	entirely your own problem.
633		662
634	=item int ev_is_default_loop (loop)	663	=item int ev_is_default_loop (loop)
635		664
636	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
637	otherwise.	666	otherwise.
638		667
639	=item unsigned int ev_loop_count (loop)	668	=item unsigned int ev_iteration (loop)
640		669
641	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
642	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>
643	happily wraps around with enough iterations.	672	and happily wraps around with enough iterations.
644		673
645	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
646	"ticks" the number of loop iterations), as it roughly corresponds with	675	"ticks" the number of loop iterations), as it roughly corresponds with
647	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.
648		678
649	=item unsigned int ev_loop_depth (loop)	679	=item unsigned int ev_depth (loop)
650		680
651	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
652	times C<ev_loop> was exited, in other words, the recursion depth.	682	times C<ev_run> was exited, in other words, the recursion depth.
653		683
654	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
655	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),
656	in which case it is higher.	686	in which case it is higher.
657		687
658	Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread	688	Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread
659	etc.), doesn't count as exit.	689	etc.), doesn't count as "exit" - consider this as a hint to avoid such
		690	ungentleman-like behaviour unless it's really convenient.
660		691
661	=item unsigned int ev_backend (loop)	692	=item unsigned int ev_backend (loop)
662		693
663	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	694	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
664	use.	695	use.
…		…
673		704
674	=item ev_now_update (loop)	705	=item ev_now_update (loop)
675		706
676	Establishes the current time by querying the kernel, updating the time	707	Establishes the current time by querying the kernel, updating the time
677	returned by C<ev_now ()> in the progress. This is a costly operation and	708	returned by C<ev_now ()> in the progress. This is a costly operation and
678	is usually done automatically within C<ev_loop ()>.	709	is usually done automatically within C<ev_run ()>.
679		710
680	This function is rarely useful, but when some event callback runs for a	711	This function is rarely useful, but when some event callback runs for a
681	very long time without entering the event loop, updating libev's idea of	712	very long time without entering the event loop, updating libev's idea of
682	the current time is a good idea.	713	the current time is a good idea.
683		714
…		…
685		716
686	=item ev_suspend (loop)	717	=item ev_suspend (loop)
687		718
688	=item ev_resume (loop)	719	=item ev_resume (loop)
689		720
690	These two functions suspend and resume a loop, for use when the loop is	721	These two functions suspend and resume an event loop, for use when the
691	not used for a while and timeouts should not be processed.	722	loop is not used for a while and timeouts should not be processed.
692		723
693	A typical use case would be an interactive program such as a game: When	724	A typical use case would be an interactive program such as a game: When
694	the user presses C<^Z> to suspend the game and resumes it an hour later it	725	the user presses C<^Z> to suspend the game and resumes it an hour later it
695	would be best to handle timeouts as if no time had actually passed while	726	would be best to handle timeouts as if no time had actually passed while
696	the program was suspended. This can be achieved by calling C<ev_suspend>	727	the program was suspended. This can be achieved by calling C<ev_suspend>
…		…
698	C<ev_resume> directly afterwards to resume timer processing.	729	C<ev_resume> directly afterwards to resume timer processing.
699		730
700	Effectively, all C<ev_timer> watchers will be delayed by the time spend	731	Effectively, all C<ev_timer> watchers will be delayed by the time spend
701	between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers	732	between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers
702	will be rescheduled (that is, they will lose any events that would have	733	will be rescheduled (that is, they will lose any events that would have
703	occured while suspended).	734	occurred while suspended).
704		735
705	After calling C<ev_suspend> you B<must not> call I<any> function on the	736	After calling C<ev_suspend> you B<must not> call I<any> function on the
706	given loop other than C<ev_resume>, and you B<must not> call C<ev_resume>	737	given loop other than C<ev_resume>, and you B<must not> call C<ev_resume>
707	without a previous call to C<ev_suspend>.	738	without a previous call to C<ev_suspend>.
708		739
709	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the	740	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the
710	event loop time (see C<ev_now_update>).	741	event loop time (see C<ev_now_update>).
711		742
712	=item ev_loop (loop, int flags)	743	=item ev_run (loop, int flags)
713		744
714	Finally, this is it, the event handler. This function usually is called	745	Finally, this is it, the event handler. This function usually is called
715	after you have initialised all your watchers and you want to start	746	after you have initialised all your watchers and you want to start
716	handling events.	747	handling events. It will ask the operating system for any new events, call
		748	the watcher callbacks, an then repeat the whole process indefinitely: This
		749	is why event loops are called I<loops>.
717		750
718	If the flags argument is specified as C<0>, it will not return until	751	If the flags argument is specified as C<0>, it will keep handling events
719	either no event watchers are active anymore or C<ev_unloop> was called.	752	until either no event watchers are active anymore or C<ev_break> was
		753	called.
720		754
721	Please note that an explicit C<ev_unloop> is usually better than	755	Please note that an explicit C<ev_break> is usually better than
722	relying on all watchers to be stopped when deciding when a program has	756	relying on all watchers to be stopped when deciding when a program has
723	finished (especially in interactive programs), but having a program	757	finished (especially in interactive programs), but having a program
724	that automatically loops as long as it has to and no longer by virtue	758	that automatically loops as long as it has to and no longer by virtue
725	of relying on its watchers stopping correctly, that is truly a thing of	759	of relying on its watchers stopping correctly, that is truly a thing of
726	beauty.	760	beauty.
727		761
728	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle	762	A flags value of C<EVRUN_NOWAIT> will look for new events, will handle
729	those events and any already outstanding ones, but will not block your	763	those events and any already outstanding ones, but will not wait and
730	process in case there are no events and will return after one iteration of	764	block your process in case there are no events and will return after one
731	the loop.	765	iteration of the loop. This is sometimes useful to poll and handle new
		766	events while doing lengthy calculations, to keep the program responsive.
732		767
733	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if	768	A flags value of C<EVRUN_ONCE> will look for new events (waiting if
734	necessary) and will handle those and any already outstanding ones. It	769	necessary) and will handle those and any already outstanding ones. It
735	will block your process until at least one new event arrives (which could	770	will block your process until at least one new event arrives (which could
736	be an event internal to libev itself, so there is no guarantee that a	771	be an event internal to libev itself, so there is no guarantee that a
737	user-registered callback will be called), and will return after one	772	user-registered callback will be called), and will return after one
738	iteration of the loop.	773	iteration of the loop.
739		774
740	This is useful if you are waiting for some external event in conjunction	775	This is useful if you are waiting for some external event in conjunction
741	with something not expressible using other libev watchers (i.e. "roll your	776	with something not expressible using other libev watchers (i.e. "roll your
742	own C<ev_loop>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is	777	own C<ev_run>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is
743	usually a better approach for this kind of thing.	778	usually a better approach for this kind of thing.
744		779
745	Here are the gory details of what C<ev_loop> does:	780	Here are the gory details of what C<ev_run> does:
746		781
		782	- Increment loop depth.
		783	- Reset the ev_break status.
747	- Before the first iteration, call any pending watchers.	784	- Before the first iteration, call any pending watchers.
		785	LOOP:
748	* If EVFLAG_FORKCHECK was used, check for a fork.	786	- If EVFLAG_FORKCHECK was used, check for a fork.
749	- If a fork was detected (by any means), queue and call all fork watchers.	787	- If a fork was detected (by any means), queue and call all fork watchers.
750	- Queue and call all prepare watchers.	788	- Queue and call all prepare watchers.
		789	- If ev_break was called, goto FINISH.
751	- If we have been forked, detach and recreate the kernel state	790	- If we have been forked, detach and recreate the kernel state
752	as to not disturb the other process.	791	as to not disturb the other process.
753	- Update the kernel state with all outstanding changes.	792	- Update the kernel state with all outstanding changes.
754	- Update the "event loop time" (ev_now ()).	793	- Update the "event loop time" (ev_now ()).
755	- Calculate for how long to sleep or block, if at all	794	- Calculate for how long to sleep or block, if at all
756	(active idle watchers, EVLOOP_NONBLOCK or not having	795	(active idle watchers, EVRUN_NOWAIT or not having
757	any active watchers at all will result in not sleeping).	796	any active watchers at all will result in not sleeping).
758	- Sleep if the I/O and timer collect interval say so.	797	- Sleep if the I/O and timer collect interval say so.
		798	- Increment loop iteration counter.
759	- Block the process, waiting for any events.	799	- Block the process, waiting for any events.
760	- Queue all outstanding I/O (fd) events.	800	- Queue all outstanding I/O (fd) events.
761	- Update the "event loop time" (ev_now ()), and do time jump adjustments.	801	- Update the "event loop time" (ev_now ()), and do time jump adjustments.
762	- Queue all expired timers.	802	- Queue all expired timers.
763	- Queue all expired periodics.	803	- Queue all expired periodics.
764	- Unless any events are pending now, queue all idle watchers.	804	- Queue all idle watchers with priority higher than that of pending events.
765	- Queue all check watchers.	805	- Queue all check watchers.
766	- Call all queued watchers in reverse order (i.e. check watchers first).	806	- Call all queued watchers in reverse order (i.e. check watchers first).
767	Signals and child watchers are implemented as I/O watchers, and will	807	Signals and child watchers are implemented as I/O watchers, and will
768	be handled here by queueing them when their watcher gets executed.	808	be handled here by queueing them when their watcher gets executed.
769	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	809	- If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT
770	were used, or there are no active watchers, return, otherwise	810	were used, or there are no active watchers, goto FINISH, otherwise
771	continue with step *.	811	continue with step LOOP.
		812	FINISH:
		813	- Reset the ev_break status iff it was EVBREAK_ONE.
		814	- Decrement the loop depth.
		815	- Return.
772		816
773	Example: Queue some jobs and then loop until no events are outstanding	817	Example: Queue some jobs and then loop until no events are outstanding
774	anymore.	818	anymore.
775		819
776	... queue jobs here, make sure they register event watchers as long	820	... queue jobs here, make sure they register event watchers as long
777	... as they still have work to do (even an idle watcher will do..)	821	... as they still have work to do (even an idle watcher will do..)
778	ev_loop (my_loop, 0);	822	ev_run (my_loop, 0);
779	... jobs done or somebody called unloop. yeah!	823	... jobs done or somebody called unloop. yeah!
780		824
781	=item ev_unloop (loop, how)	825	=item ev_break (loop, how)
782		826
783	Can be used to make a call to C<ev_loop> return early (but only after it	827	Can be used to make a call to C<ev_run> return early (but only after it
784	has processed all outstanding events). The C<how> argument must be either	828	has processed all outstanding events). The C<how> argument must be either
785	C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or	829	C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or
786	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.	830	C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return.
787		831
788	This "unloop state" will be cleared when entering C<ev_loop> again.	832	This "break state" will be cleared when entering C<ev_run> again.
789		833
790	It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls.	834	It is safe to call C<ev_break> from outside any C<ev_run> calls, too.
791		835
792	=item ev_ref (loop)	836	=item ev_ref (loop)
793		837
794	=item ev_unref (loop)	838	=item ev_unref (loop)
795		839
796	Ref/unref can be used to add or remove a reference count on the event	840	Ref/unref can be used to add or remove a reference count on the event
797	loop: Every watcher keeps one reference, and as long as the reference	841	loop: Every watcher keeps one reference, and as long as the reference
798	count is nonzero, C<ev_loop> will not return on its own.	842	count is nonzero, C<ev_run> will not return on its own.
799		843
800	This is useful when you have a watcher that you never intend to	844	This is useful when you have a watcher that you never intend to
801	unregister, but that nevertheless should not keep C<ev_loop> from	845	unregister, but that nevertheless should not keep C<ev_run> from
802	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>	846	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>
803	before stopping it.	847	before stopping it.
804		848
805	As an example, libev itself uses this for its internal signal pipe: It	849	As an example, libev itself uses this for its internal signal pipe: It
806	is not visible to the libev user and should not keep C<ev_loop> from	850	is not visible to the libev user and should not keep C<ev_run> from
807	exiting if no event watchers registered by it are active. It is also an	851	exiting if no event watchers registered by it are active. It is also an
808	excellent way to do this for generic recurring timers or from within	852	excellent way to do this for generic recurring timers or from within
809	third-party libraries. Just remember to I<unref after start> and I<ref	853	third-party libraries. Just remember to I<unref after start> and I<ref
810	before stop> (but only if the watcher wasn't active before, or was active	854	before stop> (but only if the watcher wasn't active before, or was active
811	before, respectively. Note also that libev might stop watchers itself	855	before, respectively. Note also that libev might stop watchers itself
812	(e.g. non-repeating timers) in which case you have to C<ev_ref>	856	(e.g. non-repeating timers) in which case you have to C<ev_ref>
813	in the callback).	857	in the callback).
814		858
815	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	859	Example: Create a signal watcher, but keep it from keeping C<ev_run>
816	running when nothing else is active.	860	running when nothing else is active.
817		861
818	ev_signal exitsig;	862	ev_signal exitsig;
819	ev_signal_init (&exitsig, sig_cb, SIGINT);	863	ev_signal_init (&exitsig, sig_cb, SIGINT);
820	ev_signal_start (loop, &exitsig);	864	ev_signal_start (loop, &exitsig);
…		…
865	usually doesn't make much sense to set it to a lower value than C<0.01>,	909	usually doesn't make much sense to set it to a lower value than C<0.01>,
866	as this approaches the timing granularity of most systems. Note that if	910	as this approaches the timing granularity of most systems. Note that if
867	you do transactions with the outside world and you can't increase the	911	you do transactions with the outside world and you can't increase the
868	parallelity, then this setting will limit your transaction rate (if you	912	parallelity, then this setting will limit your transaction rate (if you
869	need to poll once per transaction and the I/O collect interval is 0.01,	913	need to poll once per transaction and the I/O collect interval is 0.01,
870	then you can't do more than 100 transations per second).	914	then you can't do more than 100 transactions per second).
871		915
872	Setting the I<timeout collect interval> can improve the opportunity for	916	Setting the I<timeout collect interval> can improve the opportunity for
873	saving power, as the program will "bundle" timer callback invocations that	917	saving power, as the program will "bundle" timer callback invocations that
874	are "near" in time together, by delaying some, thus reducing the number of	918	are "near" in time together, by delaying some, thus reducing the number of
875	times the process sleeps and wakes up again. Another useful technique to	919	times the process sleeps and wakes up again. Another useful technique to
…		…
883	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);	927	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);
884		928
885	=item ev_invoke_pending (loop)	929	=item ev_invoke_pending (loop)
886		930
887	This call will simply invoke all pending watchers while resetting their	931	This call will simply invoke all pending watchers while resetting their
888	pending state. Normally, C<ev_loop> does this automatically when required,	932	pending state. Normally, C<ev_run> does this automatically when required,
889	but when overriding the invoke callback this call comes handy.	933	but when overriding the invoke callback this call comes handy. This
		934	function can be invoked from a watcher - this can be useful for example
		935	when you want to do some lengthy calculation and want to pass further
		936	event handling to another thread (you still have to make sure only one
		937	thread executes within C<ev_invoke_pending> or C<ev_run> of course).
890		938
891	=item int ev_pending_count (loop)	939	=item int ev_pending_count (loop)
892		940
893	Returns the number of pending watchers - zero indicates that no watchers	941	Returns the number of pending watchers - zero indicates that no watchers
894	are pending.	942	are pending.
895		943
896	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))	944	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))
897		945
898	This overrides the invoke pending functionality of the loop: Instead of	946	This overrides the invoke pending functionality of the loop: Instead of
899	invoking all pending watchers when there are any, C<ev_loop> will call	947	invoking all pending watchers when there are any, C<ev_run> will call
900	this callback instead. This is useful, for example, when you want to	948	this callback instead. This is useful, for example, when you want to
901	invoke the actual watchers inside another context (another thread etc.).	949	invoke the actual watchers inside another context (another thread etc.).
902		950
903	If you want to reset the callback, use C<ev_invoke_pending> as new	951	If you want to reset the callback, use C<ev_invoke_pending> as new
904	callback.	952	callback.
…		…
907		955
908	Sometimes you want to share the same loop between multiple threads. This	956	Sometimes you want to share the same loop between multiple threads. This
909	can be done relatively simply by putting mutex_lock/unlock calls around	957	can be done relatively simply by putting mutex_lock/unlock calls around
910	each call to a libev function.	958	each call to a libev function.
911		959
912	However, C<ev_loop> can run an indefinite time, so it is not feasible to	960	However, C<ev_run> can run an indefinite time, so it is not feasible
913	wait for it to return. One way around this is to wake up the loop via	961	to wait for it to return. One way around this is to wake up the event
914	C<ev_unloop> and C<av_async_send>, another way is to set these I<release>	962	loop via C<ev_break> and C<av_async_send>, another way is to set these
915	and I<acquire> callbacks on the loop.	963	I<release> and I<acquire> callbacks on the loop.
916		964
917	When set, then C<release> will be called just before the thread is	965	When set, then C<release> will be called just before the thread is
918	suspended waiting for new events, and C<acquire> is called just	966	suspended waiting for new events, and C<acquire> is called just
919	afterwards.	967	afterwards.
920		968
…		…
923		971
924	While event loop modifications are allowed between invocations of	972	While event loop modifications are allowed between invocations of
925	C<release> and C<acquire> (that's their only purpose after all), no	973	C<release> and C<acquire> (that's their only purpose after all), no
926	modifications done will affect the event loop, i.e. adding watchers will	974	modifications done will affect the event loop, i.e. adding watchers will
927	have no effect on the set of file descriptors being watched, or the time	975	have no effect on the set of file descriptors being watched, or the time
928	waited. Use an C<ev_async> watcher to wake up C<ev_loop> when you want it	976	waited. Use an C<ev_async> watcher to wake up C<ev_run> when you want it
929	to take note of any changes you made.	977	to take note of any changes you made.
930		978
931	In theory, threads executing C<ev_loop> will be async-cancel safe between	979	In theory, threads executing C<ev_run> will be async-cancel safe between
932	invocations of C<release> and C<acquire>.	980	invocations of C<release> and C<acquire>.
933		981
934	See also the locking example in the C<THREADS> section later in this	982	See also the locking example in the C<THREADS> section later in this
935	document.	983	document.
936		984
…		…
945	These two functions can be used to associate arbitrary data with a loop,	993	These two functions can be used to associate arbitrary data with a loop,
946	and are intended solely for the C<invoke_pending_cb>, C<release> and	994	and are intended solely for the C<invoke_pending_cb>, C<release> and
947	C<acquire> callbacks described above, but of course can be (ab-)used for	995	C<acquire> callbacks described above, but of course can be (ab-)used for
948	any other purpose as well.	996	any other purpose as well.
949		997
950	=item ev_loop_verify (loop)	998	=item ev_verify (loop)
951		999
952	This function only does something when C<EV_VERIFY> support has been	1000	This function only does something when C<EV_VERIFY> support has been
953	compiled in, which is the default for non-minimal builds. It tries to go	1001	compiled in, which is the default for non-minimal builds. It tries to go
954	through all internal structures and checks them for validity. If anything	1002	through all internal structures and checks them for validity. If anything
955	is found to be inconsistent, it will print an error message to standard	1003	is found to be inconsistent, it will print an error message to standard
…		…
966		1014
967	In the following description, uppercase C<TYPE> in names stands for the	1015	In the following description, uppercase C<TYPE> in names stands for the
968	watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer	1016	watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer
969	watchers and C<ev_io_start> for I/O watchers.	1017	watchers and C<ev_io_start> for I/O watchers.
970		1018
971	A watcher is a structure that you create and register to record your	1019	A watcher is an opaque structure that you allocate and register to record
972	interest in some event. For instance, if you want to wait for STDIN to	1020	your interest in some event. To make a concrete example, imagine you want
973	become readable, you would create an C<ev_io> watcher for that:	1021	to wait for STDIN to become readable, you would create an C<ev_io> watcher
		1022	for that:
974		1023
975	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)	1024	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)
976	{	1025	{
977	ev_io_stop (w);	1026	ev_io_stop (w);
978	ev_unloop (loop, EVUNLOOP_ALL);	1027	ev_break (loop, EVBREAK_ALL);
979	}	1028	}
980		1029
981	struct ev_loop *loop = ev_default_loop (0);	1030	struct ev_loop *loop = ev_default_loop (0);
982		1031
983	ev_io stdin_watcher;	1032	ev_io stdin_watcher;
984		1033
985	ev_init (&stdin_watcher, my_cb);	1034	ev_init (&stdin_watcher, my_cb);
986	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	1035	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
987	ev_io_start (loop, &stdin_watcher);	1036	ev_io_start (loop, &stdin_watcher);
988		1037
989	ev_loop (loop, 0);	1038	ev_run (loop, 0);
990		1039
991	As you can see, you are responsible for allocating the memory for your	1040	As you can see, you are responsible for allocating the memory for your
992	watcher structures (and it is I<usually> a bad idea to do this on the	1041	watcher structures (and it is I<usually> a bad idea to do this on the
993	stack).	1042	stack).
994		1043
995	Each watcher has an associated watcher structure (called C<struct ev_TYPE>	1044	Each watcher has an associated watcher structure (called C<struct ev_TYPE>
996	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).	1045	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).
997		1046
998	Each watcher structure must be initialised by a call to C<ev_init	1047	Each watcher structure must be initialised by a call to C<ev_init (watcher
999	(watcher *, callback)>, which expects a callback to be provided. This	1048	*, callback)>, which expects a callback to be provided. This callback is
1000	callback gets invoked each time the event occurs (or, in the case of I/O	1049	invoked each time the event occurs (or, in the case of I/O watchers, each
1001	watchers, each time the event loop detects that the file descriptor given	1050	time the event loop detects that the file descriptor given is readable
1002	is readable and/or writable).	1051	and/or writable).
1003		1052
1004	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>	1053	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>
1005	macro to configure it, with arguments specific to the watcher type. There	1054	macro to configure it, with arguments specific to the watcher type. There
1006	is also a macro to combine initialisation and setting in one call: C<<	1055	is also a macro to combine initialisation and setting in one call: C<<
1007	ev_TYPE_init (watcher *, callback, ...) >>.	1056	ev_TYPE_init (watcher *, callback, ...) >>.
…		…
1030	=item C<EV_WRITE>	1079	=item C<EV_WRITE>
1031		1080
1032	The file descriptor in the C<ev_io> watcher has become readable and/or	1081	The file descriptor in the C<ev_io> watcher has become readable and/or
1033	writable.	1082	writable.
1034		1083
1035	=item C<EV_TIMEOUT>	1084	=item C<EV_TIMER>
1036		1085
1037	The C<ev_timer> watcher has timed out.	1086	The C<ev_timer> watcher has timed out.
1038		1087
1039	=item C<EV_PERIODIC>	1088	=item C<EV_PERIODIC>
1040		1089
…		…
1058		1107
1059	=item C<EV_PREPARE>	1108	=item C<EV_PREPARE>
1060		1109
1061	=item C<EV_CHECK>	1110	=item C<EV_CHECK>
1062		1111
1063	All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts	1112	All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts
1064	to gather new events, and all C<ev_check> watchers are invoked just after	1113	to gather new events, and all C<ev_check> watchers are invoked just after
1065	C<ev_loop> has gathered them, but before it invokes any callbacks for any	1114	C<ev_run> has gathered them, but before it invokes any callbacks for any
1066	received events. Callbacks of both watcher types can start and stop as	1115	received events. Callbacks of both watcher types can start and stop as
1067	many watchers as they want, and all of them will be taken into account	1116	many watchers as they want, and all of them will be taken into account
1068	(for example, a C<ev_prepare> watcher might start an idle watcher to keep	1117	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
1069	C<ev_loop> from blocking).	1118	C<ev_run> from blocking).
1070		1119
1071	=item C<EV_EMBED>	1120	=item C<EV_EMBED>
1072		1121
1073	The embedded event loop specified in the C<ev_embed> watcher needs attention.	1122	The embedded event loop specified in the C<ev_embed> watcher needs attention.
1074		1123
1075	=item C<EV_FORK>	1124	=item C<EV_FORK>
1076		1125
1077	The event loop has been resumed in the child process after fork (see	1126	The event loop has been resumed in the child process after fork (see
1078	C<ev_fork>).	1127	C<ev_fork>).
		1128
		1129	=item C<EV_CLEANUP>
		1130
		1131	The event loop is about to be destroyed (see C<ev_cleanup>).
1079		1132
1080	=item C<EV_ASYNC>	1133	=item C<EV_ASYNC>
1081		1134
1082	The given async watcher has been asynchronously notified (see C<ev_async>).	1135	The given async watcher has been asynchronously notified (see C<ev_async>).
1083		1136
…		…
1255		1308
1256	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related	1309	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related
1257	functions that do not need a watcher.	1310	functions that do not need a watcher.
1258		1311
1259	=back	1312	=back
1260
1261		1313
1262	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	1314	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
1263		1315
1264	Each watcher has, by default, a member C<void *data> that you can change	1316	Each watcher has, by default, a member C<void *data> that you can change
1265	and read at any time: libev will completely ignore it. This can be used	1317	and read at any time: libev will completely ignore it. This can be used
…		…
1321	t2_cb (EV_P_ ev_timer *w, int revents)	1373	t2_cb (EV_P_ ev_timer *w, int revents)
1322	{	1374	{
1323	struct my_biggy big = (struct my_biggy *)	1375	struct my_biggy big = (struct my_biggy *)
1324	(((char *)w) - offsetof (struct my_biggy, t2));	1376	(((char *)w) - offsetof (struct my_biggy, t2));
1325	}	1377	}
		1378
		1379	=head2 WATCHER STATES
		1380
		1381	There are various watcher states mentioned throughout this manual -
		1382	active, pending and so on. In this section these states and the rules to
		1383	transition between them will be described in more detail - and while these
		1384	rules might look complicated, they usually do "the right thing".
		1385
		1386	=over 4
		1387
		1388	=item initialiased
		1389
		1390	Before a watcher can be registered with the event looop it has to be
		1391	initialised. This can be done with a call to C<ev_TYPE_init>, or calls to
		1392	C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function.
		1393
		1394	In this state it is simply some block of memory that is suitable for use
		1395	in an event loop. It can be moved around, freed, reused etc. at will.
		1396
		1397	=item started/running/active
		1398
		1399	Once a watcher has been started with a call to C<ev_TYPE_start> it becomes
		1400	property of the event loop, and is actively waiting for events. While in
		1401	this state it cannot be accessed (except in a few documented ways), moved,
		1402	freed or anything else - the only legal thing is to keep a pointer to it,
		1403	and call libev functions on it that are documented to work on active watchers.
		1404
		1405	=item pending
		1406
		1407	If a watcher is active and libev determines that an event it is interested
		1408	in has occurred (such as a timer expiring), it will become pending. It will
		1409	stay in this pending state until either it is stopped or its callback is
		1410	about to be invoked, so it is not normally pending inside the watcher
		1411	callback.
		1412
		1413	The watcher might or might not be active while it is pending (for example,
		1414	an expired non-repeating timer can be pending but no longer active). If it
		1415	is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>),
		1416	but it is still property of the event loop at this time, so cannot be
		1417	moved, freed or reused. And if it is active the rules described in the
		1418	previous item still apply.
		1419
		1420	It is also possible to feed an event on a watcher that is not active (e.g.
		1421	via C<ev_feed_event>), in which case it becomes pending without being
		1422	active.
		1423
		1424	=item stopped
		1425
		1426	A watcher can be stopped implicitly by libev (in which case it might still
		1427	be pending), or explicitly by calling its C<ev_TYPE_stop> function. The
		1428	latter will clear any pending state the watcher might be in, regardless
		1429	of whether it was active or not, so stopping a watcher explicitly before
		1430	freeing it is often a good idea.
		1431
		1432	While stopped (and not pending) the watcher is essentially in the
		1433	initialised state, that is it can be reused, moved, modified in any way
		1434	you wish.
		1435
		1436	=back
1326		1437
1327	=head2 WATCHER PRIORITY MODELS	1438	=head2 WATCHER PRIORITY MODELS
1328		1439
1329	Many event loops support I<watcher priorities>, which are usually small	1440	Many event loops support I<watcher priorities>, which are usually small
1330	integers that influence the ordering of event callback invocation	1441	integers that influence the ordering of event callback invocation
…		…
1373		1484
1374	For example, to emulate how many other event libraries handle priorities,	1485	For example, to emulate how many other event libraries handle priorities,
1375	you can associate an C<ev_idle> watcher to each such watcher, and in	1486	you can associate an C<ev_idle> watcher to each such watcher, and in
1376	the normal watcher callback, you just start the idle watcher. The real	1487	the normal watcher callback, you just start the idle watcher. The real
1377	processing is done in the idle watcher callback. This causes libev to	1488	processing is done in the idle watcher callback. This causes libev to
1378	continously poll and process kernel event data for the watcher, but when	1489	continuously poll and process kernel event data for the watcher, but when
1379	the lock-out case is known to be rare (which in turn is rare :), this is	1490	the lock-out case is known to be rare (which in turn is rare :), this is
1380	workable.	1491	workable.
1381		1492
1382	Usually, however, the lock-out model implemented that way will perform	1493	Usually, however, the lock-out model implemented that way will perform
1383	miserably under the type of load it was designed to handle. In that case,	1494	miserably under the type of load it was designed to handle. In that case,
…		…
1397	{	1508	{
1398	// stop the I/O watcher, we received the event, but	1509	// stop the I/O watcher, we received the event, but
1399	// are not yet ready to handle it.	1510	// are not yet ready to handle it.
1400	ev_io_stop (EV_A_ w);	1511	ev_io_stop (EV_A_ w);
1401		1512
1402	// start the idle watcher to ahndle the actual event.	1513	// start the idle watcher to handle the actual event.
1403	// it will not be executed as long as other watchers	1514	// it will not be executed as long as other watchers
1404	// with the default priority are receiving events.	1515	// with the default priority are receiving events.
1405	ev_idle_start (EV_A_ &idle);	1516	ev_idle_start (EV_A_ &idle);
1406	}	1517	}
1407		1518
…		…
1461		1572
1462	If you cannot use non-blocking mode, then force the use of a	1573	If you cannot use non-blocking mode, then force the use of a
1463	known-to-be-good backend (at the time of this writing, this includes only	1574	known-to-be-good backend (at the time of this writing, this includes only
1464	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file	1575	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file
1465	descriptors for which non-blocking operation makes no sense (such as	1576	descriptors for which non-blocking operation makes no sense (such as
1466	files) - libev doesn't guarentee any specific behaviour in that case.	1577	files) - libev doesn't guarantee any specific behaviour in that case.
1467		1578
1468	Another thing you have to watch out for is that it is quite easy to	1579	Another thing you have to watch out for is that it is quite easy to
1469	receive "spurious" readiness notifications, that is your callback might	1580	receive "spurious" readiness notifications, that is your callback might
1470	be called with C<EV_READ> but a subsequent C<read>(2) will actually block	1581	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
1471	because there is no data. Not only are some backends known to create a	1582	because there is no data. Not only are some backends known to create a
…		…
1536		1647
1537	So when you encounter spurious, unexplained daemon exits, make sure you	1648	So when you encounter spurious, unexplained daemon exits, make sure you
1538	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon	1649	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon
1539	somewhere, as that would have given you a big clue).	1650	somewhere, as that would have given you a big clue).
1540		1651
		1652	=head3 The special problem of accept()ing when you can't
		1653
		1654	Many implementations of the POSIX C<accept> function (for example,
		1655	found in post-2004 Linux) have the peculiar behaviour of not removing a
		1656	connection from the pending queue in all error cases.
		1657
		1658	For example, larger servers often run out of file descriptors (because
		1659	of resource limits), causing C<accept> to fail with C<ENFILE> but not
		1660	rejecting the connection, leading to libev signalling readiness on
		1661	the next iteration again (the connection still exists after all), and
		1662	typically causing the program to loop at 100% CPU usage.
		1663
		1664	Unfortunately, the set of errors that cause this issue differs between
		1665	operating systems, there is usually little the app can do to remedy the
		1666	situation, and no known thread-safe method of removing the connection to
		1667	cope with overload is known (to me).
		1668
		1669	One of the easiest ways to handle this situation is to just ignore it
		1670	- when the program encounters an overload, it will just loop until the
		1671	situation is over. While this is a form of busy waiting, no OS offers an
		1672	event-based way to handle this situation, so it's the best one can do.
		1673
		1674	A better way to handle the situation is to log any errors other than
		1675	C<EAGAIN> and C<EWOULDBLOCK>, making sure not to flood the log with such
		1676	messages, and continue as usual, which at least gives the user an idea of
		1677	what could be wrong ("raise the ulimit!"). For extra points one could stop
		1678	the C<ev_io> watcher on the listening fd "for a while", which reduces CPU
		1679	usage.
		1680
		1681	If your program is single-threaded, then you could also keep a dummy file
		1682	descriptor for overload situations (e.g. by opening F</dev/null>), and
		1683	when you run into C<ENFILE> or C<EMFILE>, close it, run C<accept>,
		1684	close that fd, and create a new dummy fd. This will gracefully refuse
		1685	clients under typical overload conditions.
		1686
		1687	The last way to handle it is to simply log the error and C<exit>, as
		1688	is often done with C<malloc> failures, but this results in an easy
		1689	opportunity for a DoS attack.
1541		1690
1542	=head3 Watcher-Specific Functions	1691	=head3 Watcher-Specific Functions
1543		1692
1544	=over 4	1693	=over 4
1545		1694
…		…
1577	...	1726	...
1578	struct ev_loop *loop = ev_default_init (0);	1727	struct ev_loop *loop = ev_default_init (0);
1579	ev_io stdin_readable;	1728	ev_io stdin_readable;
1580	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1729	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1581	ev_io_start (loop, &stdin_readable);	1730	ev_io_start (loop, &stdin_readable);
1582	ev_loop (loop, 0);	1731	ev_run (loop, 0);
1583		1732
1584		1733
1585	=head2 C<ev_timer> - relative and optionally repeating timeouts	1734	=head2 C<ev_timer> - relative and optionally repeating timeouts
1586		1735
1587	Timer watchers are simple relative timers that generate an event after a	1736	Timer watchers are simple relative timers that generate an event after a
…		…
1596	The callback is guaranteed to be invoked only I<after> its timeout has	1745	The callback is guaranteed to be invoked only I<after> its timeout has
1597	passed (not I<at>, so on systems with very low-resolution clocks this	1746	passed (not I<at>, so on systems with very low-resolution clocks this
1598	might introduce a small delay). If multiple timers become ready during the	1747	might introduce a small delay). If multiple timers become ready during the
1599	same loop iteration then the ones with earlier time-out values are invoked	1748	same loop iteration then the ones with earlier time-out values are invoked
1600	before ones of the same priority with later time-out values (but this is	1749	before ones of the same priority with later time-out values (but this is
1601	no longer true when a callback calls C<ev_loop> recursively).	1750	no longer true when a callback calls C<ev_run> recursively).
1602		1751
1603	=head3 Be smart about timeouts	1752	=head3 Be smart about timeouts
1604		1753
1605	Many real-world problems involve some kind of timeout, usually for error	1754	Many real-world problems involve some kind of timeout, usually for error
1606	recovery. A typical example is an HTTP request - if the other side hangs,	1755	recovery. A typical example is an HTTP request - if the other side hangs,
…		…
1692	ev_tstamp timeout = last_activity + 60.;	1841	ev_tstamp timeout = last_activity + 60.;
1693		1842
1694	// if last_activity + 60. is older than now, we did time out	1843	// if last_activity + 60. is older than now, we did time out
1695	if (timeout < now)	1844	if (timeout < now)
1696	{	1845	{
1697	// timeout occured, take action	1846	// timeout occurred, take action
1698	}	1847	}
1699	else	1848	else
1700	{	1849	{
1701	// callback was invoked, but there was some activity, re-arm	1850	// callback was invoked, but there was some activity, re-arm
1702	// the watcher to fire in last_activity + 60, which is	1851	// the watcher to fire in last_activity + 60, which is
…		…
1724	to the current time (meaning we just have some activity :), then call the	1873	to the current time (meaning we just have some activity :), then call the
1725	callback, which will "do the right thing" and start the timer:	1874	callback, which will "do the right thing" and start the timer:
1726		1875
1727	ev_init (timer, callback);	1876	ev_init (timer, callback);
1728	last_activity = ev_now (loop);	1877	last_activity = ev_now (loop);
1729	callback (loop, timer, EV_TIMEOUT);	1878	callback (loop, timer, EV_TIMER);
1730		1879
1731	And when there is some activity, simply store the current time in	1880	And when there is some activity, simply store the current time in
1732	C<last_activity>, no libev calls at all:	1881	C<last_activity>, no libev calls at all:
1733		1882
1734	last_actiivty = ev_now (loop);	1883	last_activity = ev_now (loop);
1735		1884
1736	This technique is slightly more complex, but in most cases where the	1885	This technique is slightly more complex, but in most cases where the
1737	time-out is unlikely to be triggered, much more efficient.	1886	time-out is unlikely to be triggered, much more efficient.
1738		1887
1739	Changing the timeout is trivial as well (if it isn't hard-coded in the	1888	Changing the timeout is trivial as well (if it isn't hard-coded in the
…		…
1777		1926
1778	=head3 The special problem of time updates	1927	=head3 The special problem of time updates
1779		1928
1780	Establishing the current time is a costly operation (it usually takes at	1929	Establishing the current time is a costly operation (it usually takes at
1781	least two system calls): EV therefore updates its idea of the current	1930	least two system calls): EV therefore updates its idea of the current
1782	time only before and after C<ev_loop> collects new events, which causes a	1931	time only before and after C<ev_run> collects new events, which causes a
1783	growing difference between C<ev_now ()> and C<ev_time ()> when handling	1932	growing difference between C<ev_now ()> and C<ev_time ()> when handling
1784	lots of events in one iteration.	1933	lots of events in one iteration.
1785		1934
1786	The relative timeouts are calculated relative to the C<ev_now ()>	1935	The relative timeouts are calculated relative to the C<ev_now ()>
1787	time. This is usually the right thing as this timestamp refers to the time	1936	time. This is usually the right thing as this timestamp refers to the time
…		…
1865	Returns the remaining time until a timer fires. If the timer is active,	2014	Returns the remaining time until a timer fires. If the timer is active,
1866	then this time is relative to the current event loop time, otherwise it's	2015	then this time is relative to the current event loop time, otherwise it's
1867	the timeout value currently configured.	2016	the timeout value currently configured.
1868		2017
1869	That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns	2018	That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns
1870	C<5>. When the timer is started and one second passes, C<ev_timer_remain>	2019	C<5>. When the timer is started and one second passes, C<ev_timer_remaining>
1871	will return C<4>. When the timer expires and is restarted, it will return	2020	will return C<4>. When the timer expires and is restarted, it will return
1872	roughly C<7> (likely slightly less as callback invocation takes some time,	2021	roughly C<7> (likely slightly less as callback invocation takes some time,
1873	too), and so on.	2022	too), and so on.
1874		2023
1875	=item ev_tstamp repeat [read-write]	2024	=item ev_tstamp repeat [read-write]
…		…
1904	}	2053	}
1905		2054
1906	ev_timer mytimer;	2055	ev_timer mytimer;
1907	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	2056	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1908	ev_timer_again (&mytimer); /* start timer */	2057	ev_timer_again (&mytimer); /* start timer */
1909	ev_loop (loop, 0);	2058	ev_run (loop, 0);
1910		2059
1911	// and in some piece of code that gets executed on any "activity":	2060	// and in some piece of code that gets executed on any "activity":
1912	// reset the timeout to start ticking again at 10 seconds	2061	// reset the timeout to start ticking again at 10 seconds
1913	ev_timer_again (&mytimer);	2062	ev_timer_again (&mytimer);
1914		2063
…		…
1940		2089
1941	As with timers, the callback is guaranteed to be invoked only when the	2090	As with timers, the callback is guaranteed to be invoked only when the
1942	point in time where it is supposed to trigger has passed. If multiple	2091	point in time where it is supposed to trigger has passed. If multiple
1943	timers become ready during the same loop iteration then the ones with	2092	timers become ready during the same loop iteration then the ones with
1944	earlier time-out values are invoked before ones with later time-out values	2093	earlier time-out values are invoked before ones with later time-out values
1945	(but this is no longer true when a callback calls C<ev_loop> recursively).	2094	(but this is no longer true when a callback calls C<ev_run> recursively).
1946		2095
1947	=head3 Watcher-Specific Functions and Data Members	2096	=head3 Watcher-Specific Functions and Data Members
1948		2097
1949	=over 4	2098	=over 4
1950		2099
…		…
2078	Example: Call a callback every hour, or, more precisely, whenever the	2227	Example: Call a callback every hour, or, more precisely, whenever the
2079	system time is divisible by 3600. The callback invocation times have	2228	system time is divisible by 3600. The callback invocation times have
2080	potentially a lot of jitter, but good long-term stability.	2229	potentially a lot of jitter, but good long-term stability.
2081		2230
2082	static void	2231	static void
2083	clock_cb (struct ev_loop *loop, ev_io *w, int revents)	2232	clock_cb (struct ev_loop *loop, ev_periodic *w, int revents)
2084	{	2233	{
2085	... its now a full hour (UTC, or TAI or whatever your clock follows)	2234	... its now a full hour (UTC, or TAI or whatever your clock follows)
2086	}	2235	}
2087		2236
2088	ev_periodic hourly_tick;	2237	ev_periodic hourly_tick;
…		…
2111		2260
2112	=head2 C<ev_signal> - signal me when a signal gets signalled!	2261	=head2 C<ev_signal> - signal me when a signal gets signalled!
2113		2262
2114	Signal watchers will trigger an event when the process receives a specific	2263	Signal watchers will trigger an event when the process receives a specific
2115	signal one or more times. Even though signals are very asynchronous, libev	2264	signal one or more times. Even though signals are very asynchronous, libev
2116	will try it's best to deliver signals synchronously, i.e. as part of the	2265	will try its best to deliver signals synchronously, i.e. as part of the
2117	normal event processing, like any other event.	2266	normal event processing, like any other event.
2118		2267
2119	If you want signals to be delivered truly asynchronously, just use	2268	If you want signals to be delivered truly asynchronously, just use
2120	C<sigaction> as you would do without libev and forget about sharing	2269	C<sigaction> as you would do without libev and forget about sharing
2121	the signal. You can even use C<ev_async> from a signal handler to	2270	the signal. You can even use C<ev_async> from a signal handler to
…		…
2160	In current versions of libev, the signal will not be blocked indefinitely	2309	In current versions of libev, the signal will not be blocked indefinitely
2161	unless you use the C<signalfd> API (C<EV_SIGNALFD>). While this reduces	2310	unless you use the C<signalfd> API (C<EV_SIGNALFD>). While this reduces
2162	the window of opportunity for problems, it will not go away, as libev	2311	the window of opportunity for problems, it will not go away, as libev
2163	I<has> to modify the signal mask, at least temporarily.	2312	I<has> to modify the signal mask, at least temporarily.
2164		2313
2165	So I can't stress this enough I<if you do not reset your signal mask	2314	So I can't stress this enough: I<If you do not reset your signal mask when
2166	when you expect it to be empty, you have a race condition in your	2315	you expect it to be empty, you have a race condition in your code>. This
2167	program>. This is not a libev-specific thing, this is true for most event	2316	is not a libev-specific thing, this is true for most event libraries.
2168	libraries.
2169		2317
2170	=head3 Watcher-Specific Functions and Data Members	2318	=head3 Watcher-Specific Functions and Data Members
2171		2319
2172	=over 4	2320	=over 4
2173		2321
…		…
2189	Example: Try to exit cleanly on SIGINT.	2337	Example: Try to exit cleanly on SIGINT.
2190		2338
2191	static void	2339	static void
2192	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)	2340	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)
2193	{	2341	{
2194	ev_unloop (loop, EVUNLOOP_ALL);	2342	ev_break (loop, EVBREAK_ALL);
2195	}	2343	}
2196		2344
2197	ev_signal signal_watcher;	2345	ev_signal signal_watcher;
2198	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	2346	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
2199	ev_signal_start (loop, &signal_watcher);	2347	ev_signal_start (loop, &signal_watcher);
…		…
2585		2733
2586	Prepare and check watchers are usually (but not always) used in pairs:	2734	Prepare and check watchers are usually (but not always) used in pairs:
2587	prepare watchers get invoked before the process blocks and check watchers	2735	prepare watchers get invoked before the process blocks and check watchers
2588	afterwards.	2736	afterwards.
2589		2737
2590	You I<must not> call C<ev_loop> or similar functions that enter	2738	You I<must not> call C<ev_run> or similar functions that enter
2591	the current event loop from either C<ev_prepare> or C<ev_check>	2739	the current event loop from either C<ev_prepare> or C<ev_check>
2592	watchers. Other loops than the current one are fine, however. The	2740	watchers. Other loops than the current one are fine, however. The
2593	rationale behind this is that you do not need to check for recursion in	2741	rationale behind this is that you do not need to check for recursion in
2594	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,	2742	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,
2595	C<ev_check> so if you have one watcher of each kind they will always be	2743	C<ev_check> so if you have one watcher of each kind they will always be
…		…
2763		2911
2764	if (timeout >= 0)	2912	if (timeout >= 0)
2765	// create/start timer	2913	// create/start timer
2766		2914
2767	// poll	2915	// poll
2768	ev_loop (EV_A_ 0);	2916	ev_run (EV_A_ 0);
2769		2917
2770	// stop timer again	2918	// stop timer again
2771	if (timeout >= 0)	2919	if (timeout >= 0)
2772	ev_timer_stop (EV_A_ &to);	2920	ev_timer_stop (EV_A_ &to);
2773		2921
…		…
2851	if you do not want that, you need to temporarily stop the embed watcher).	2999	if you do not want that, you need to temporarily stop the embed watcher).
2852		3000
2853	=item ev_embed_sweep (loop, ev_embed *)	3001	=item ev_embed_sweep (loop, ev_embed *)
2854		3002
2855	Make a single, non-blocking sweep over the embedded loop. This works	3003	Make a single, non-blocking sweep over the embedded loop. This works
2856	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	3004	similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most
2857	appropriate way for embedded loops.	3005	appropriate way for embedded loops.
2858		3006
2859	=item struct ev_loop *other [read-only]	3007	=item struct ev_loop *other [read-only]
2860		3008
2861	The embedded event loop.	3009	The embedded event loop.
…		…
2921	C<ev_default_fork> cheats and calls it in the wrong process, the fork	3069	C<ev_default_fork> cheats and calls it in the wrong process, the fork
2922	handlers will be invoked, too, of course.	3070	handlers will be invoked, too, of course.
2923		3071
2924	=head3 The special problem of life after fork - how is it possible?	3072	=head3 The special problem of life after fork - how is it possible?
2925		3073
2926	Most uses of C<fork()> consist of forking, then some simple calls to ste	3074	Most uses of C<fork()> consist of forking, then some simple calls to set
2927	up/change the process environment, followed by a call to C<exec()>. This	3075	up/change the process environment, followed by a call to C<exec()>. This
2928	sequence should be handled by libev without any problems.	3076	sequence should be handled by libev without any problems.
2929		3077
2930	This changes when the application actually wants to do event handling	3078	This changes when the application actually wants to do event handling
2931	in the child, or both parent in child, in effect "continuing" after the	3079	in the child, or both parent in child, in effect "continuing" after the
…		…
2947	disadvantage of having to use multiple event loops (which do not support	3095	disadvantage of having to use multiple event loops (which do not support
2948	signal watchers).	3096	signal watchers).
2949		3097
2950	When this is not possible, or you want to use the default loop for	3098	When this is not possible, or you want to use the default loop for
2951	other reasons, then in the process that wants to start "fresh", call	3099	other reasons, then in the process that wants to start "fresh", call
2952	C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying	3100	C<ev_loop_destroy (EV_DEFAULT)> followed by C<ev_default_loop (...)>.
2953	the default loop will "orphan" (not stop) all registered watchers, so you	3101	Destroying the default loop will "orphan" (not stop) all registered
2954	have to be careful not to execute code that modifies those watchers. Note	3102	watchers, so you have to be careful not to execute code that modifies
2955	also that in that case, you have to re-register any signal watchers.	3103	those watchers. Note also that in that case, you have to re-register any
		3104	signal watchers.
2956		3105
2957	=head3 Watcher-Specific Functions and Data Members	3106	=head3 Watcher-Specific Functions and Data Members
2958		3107
2959	=over 4	3108	=over 4
2960		3109
2961	=item ev_fork_init (ev_signal *, callback)	3110	=item ev_fork_init (ev_fork *, callback)
2962		3111
2963	Initialises and configures the fork watcher - it has no parameters of any	3112	Initialises and configures the fork watcher - it has no parameters of any
2964	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,	3113	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
2965	believe me.	3114	really.
2966		3115
2967	=back	3116	=back
2968		3117
2969		3118
		3119	=head2 C<ev_cleanup> - even the best things end
		3120
		3121	Cleanup watchers are called just before the event loop is being destroyed
		3122	by a call to C<ev_loop_destroy>.
		3123
		3124	While there is no guarantee that the event loop gets destroyed, cleanup
		3125	watchers provide a convenient method to install cleanup hooks for your
		3126	program, worker threads and so on - you just to make sure to destroy the
		3127	loop when you want them to be invoked.
		3128
		3129	Cleanup watchers are invoked in the same way as any other watcher. Unlike
		3130	all other watchers, they do not keep a reference to the event loop (which
		3131	makes a lot of sense if you think about it). Like all other watchers, you
		3132	can call libev functions in the callback, except C<ev_cleanup_start>.
		3133
		3134	=head3 Watcher-Specific Functions and Data Members
		3135
		3136	=over 4
		3137
		3138	=item ev_cleanup_init (ev_cleanup *, callback)
		3139
		3140	Initialises and configures the cleanup watcher - it has no parameters of
		3141	any kind. There is a C<ev_cleanup_set> macro, but using it is utterly
		3142	pointless, I assure you.
		3143
		3144	=back
		3145
		3146	Example: Register an atexit handler to destroy the default loop, so any
		3147	cleanup functions are called.
		3148
		3149	static void
		3150	program_exits (void)
		3151	{
		3152	ev_loop_destroy (EV_DEFAULT_UC);
		3153	}
		3154
		3155	...
		3156	atexit (program_exits);
		3157
		3158
2970	=head2 C<ev_async> - how to wake up another event loop	3159	=head2 C<ev_async> - how to wake up an event loop
2971		3160
2972	In general, you cannot use an C<ev_loop> from multiple threads or other	3161	In general, you cannot use an C<ev_run> from multiple threads or other
2973	asynchronous sources such as signal handlers (as opposed to multiple event	3162	asynchronous sources such as signal handlers (as opposed to multiple event
2974	loops - those are of course safe to use in different threads).	3163	loops - those are of course safe to use in different threads).
2975		3164
2976	Sometimes, however, you need to wake up another event loop you do not	3165	Sometimes, however, you need to wake up an event loop you do not control,
2977	control, for example because it belongs to another thread. This is what	3166	for example because it belongs to another thread. This is what C<ev_async>
2978	C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you	3167	watchers do: as long as the C<ev_async> watcher is active, you can signal
2979	can signal it by calling C<ev_async_send>, which is thread- and signal	3168	it by calling C<ev_async_send>, which is thread- and signal safe.
2980	safe.
2981		3169
2982	This functionality is very similar to C<ev_signal> watchers, as signals,	3170	This functionality is very similar to C<ev_signal> watchers, as signals,
2983	too, are asynchronous in nature, and signals, too, will be compressed	3171	too, are asynchronous in nature, and signals, too, will be compressed
2984	(i.e. the number of callback invocations may be less than the number of	3172	(i.e. the number of callback invocations may be less than the number of
2985	C<ev_async_sent> calls).	3173	C<ev_async_sent> calls).
…		…
3140		3328
3141	If C<timeout> is less than 0, then no timeout watcher will be	3329	If C<timeout> is less than 0, then no timeout watcher will be
3142	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and	3330	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and
3143	repeat = 0) will be started. C<0> is a valid timeout.	3331	repeat = 0) will be started. C<0> is a valid timeout.
3144		3332
3145	The callback has the type C<void (*cb)(int revents, void *arg)> and gets	3333	The callback has the type C<void (*cb)(int revents, void *arg)> and is
3146	passed an C<revents> set like normal event callbacks (a combination of	3334	passed an C<revents> set like normal event callbacks (a combination of
3147	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>	3335	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMER>) and the C<arg>
3148	value passed to C<ev_once>. Note that it is possible to receive I<both>	3336	value passed to C<ev_once>. Note that it is possible to receive I<both>
3149	a timeout and an io event at the same time - you probably should give io	3337	a timeout and an io event at the same time - you probably should give io
3150	events precedence.	3338	events precedence.
3151		3339
3152	Example: wait up to ten seconds for data to appear on STDIN_FILENO.	3340	Example: wait up to ten seconds for data to appear on STDIN_FILENO.
3153		3341
3154	static void stdin_ready (int revents, void *arg)	3342	static void stdin_ready (int revents, void *arg)
3155	{	3343	{
3156	if (revents & EV_READ)	3344	if (revents & EV_READ)
3157	/* stdin might have data for us, joy! */;	3345	/* stdin might have data for us, joy! */;
3158	else if (revents & EV_TIMEOUT)	3346	else if (revents & EV_TIMER)
3159	/* doh, nothing entered */;	3347	/* doh, nothing entered */;
3160	}	3348	}
3161		3349
3162	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	3350	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
3163		3351
…		…
3193	=item * Priorities are not currently supported. Initialising priorities	3381	=item * Priorities are not currently supported. Initialising priorities
3194	will fail and all watchers will have the same priority, even though there	3382	will fail and all watchers will have the same priority, even though there
3195	is an ev_pri field.	3383	is an ev_pri field.
3196		3384
3197	=item * In libevent, the last base created gets the signals, in libev, the	3385	=item * In libevent, the last base created gets the signals, in libev, the
3198	first base created (== the default loop) gets the signals.	3386	base that registered the signal gets the signals.
3199		3387
3200	=item * Other members are not supported.	3388	=item * Other members are not supported.
3201		3389
3202	=item * The libev emulation is I<not> ABI compatible to libevent, you need	3390	=item * The libev emulation is I<not> ABI compatible to libevent, you need
3203	to use the libev header file and library.	3391	to use the libev header file and library.
…		…
3297	myclass obj;	3485	myclass obj;
3298	ev::io iow;	3486	ev::io iow;
3299	iow.set <myclass, &myclass::io_cb> (&obj);	3487	iow.set <myclass, &myclass::io_cb> (&obj);
3300		3488
3301	=item w->set (object *)	3489	=item w->set (object *)
3302
3303	This is an B<experimental> feature that might go away in a future version.
3304		3490
3305	This is a variation of a method callback - leaving out the method to call	3491	This is a variation of a method callback - leaving out the method to call
3306	will default the method to C<operator ()>, which makes it possible to use	3492	will default the method to C<operator ()>, which makes it possible to use
3307	functor objects without having to manually specify the C<operator ()> all	3493	functor objects without having to manually specify the C<operator ()> all
3308	the time. Incidentally, you can then also leave out the template argument	3494	the time. Incidentally, you can then also leave out the template argument
…		…
3348	Associates a different C<struct ev_loop> with this watcher. You can only	3534	Associates a different C<struct ev_loop> with this watcher. You can only
3349	do this when the watcher is inactive (and not pending either).	3535	do this when the watcher is inactive (and not pending either).
3350		3536
3351	=item w->set ([arguments])	3537	=item w->set ([arguments])
3352		3538
3353	Basically the same as C<ev_TYPE_set>, with the same arguments. Must be	3539	Basically the same as C<ev_TYPE_set>, with the same arguments. Either this
3354	called at least once. Unlike the C counterpart, an active watcher gets	3540	method or a suitable start method must be called at least once. Unlike the
3355	automatically stopped and restarted when reconfiguring it with this	3541	C counterpart, an active watcher gets automatically stopped and restarted
3356	method.	3542	when reconfiguring it with this method.
3357		3543
3358	=item w->start ()	3544	=item w->start ()
3359		3545
3360	Starts the watcher. Note that there is no C<loop> argument, as the	3546	Starts the watcher. Note that there is no C<loop> argument, as the
3361	constructor already stores the event loop.	3547	constructor already stores the event loop.
3362		3548
		3549	=item w->start ([arguments])
		3550
		3551	Instead of calling C<set> and C<start> methods separately, it is often
		3552	convenient to wrap them in one call. Uses the same type of arguments as
		3553	the configure C<set> method of the watcher.
		3554
3363	=item w->stop ()	3555	=item w->stop ()
3364		3556
3365	Stops the watcher if it is active. Again, no C<loop> argument.	3557	Stops the watcher if it is active. Again, no C<loop> argument.
3366		3558
3367	=item w->again () (C<ev::timer>, C<ev::periodic> only)	3559	=item w->again () (C<ev::timer>, C<ev::periodic> only)
…		…
3379		3571
3380	=back	3572	=back
3381		3573
3382	=back	3574	=back
3383		3575
3384	Example: Define a class with an IO and idle watcher, start one of them in	3576	Example: Define a class with two I/O and idle watchers, start the I/O
3385	the constructor.	3577	watchers in the constructor.
3386		3578
3387	class myclass	3579	class myclass
3388	{	3580	{
3389	ev::io io ; void io_cb (ev::io &w, int revents);	3581	ev::io io ; void io_cb (ev::io &w, int revents);
		3582	ev::io2 io2 ; void io2_cb (ev::io &w, int revents);
3390	ev::idle idle; void idle_cb (ev::idle &w, int revents);	3583	ev::idle idle; void idle_cb (ev::idle &w, int revents);
3391		3584
3392	myclass (int fd)	3585	myclass (int fd)
3393	{	3586	{
3394	io .set <myclass, &myclass::io_cb > (this);	3587	io .set <myclass, &myclass::io_cb > (this);
		3588	io2 .set <myclass, &myclass::io2_cb > (this);
3395	idle.set <myclass, &myclass::idle_cb> (this);	3589	idle.set <myclass, &myclass::idle_cb> (this);
3396		3590
3397	io.start (fd, ev::READ);	3591	io.set (fd, ev::WRITE); // configure the watcher
		3592	io.start (); // start it whenever convenient
		3593
		3594	io2.start (fd, ev::READ); // set + start in one call
3398	}	3595	}
3399	};	3596	};
3400		3597
3401		3598
3402	=head1 OTHER LANGUAGE BINDINGS	3599	=head1 OTHER LANGUAGE BINDINGS
…		…
3450	Erkki Seppala has written Ocaml bindings for libev, to be found at	3647	Erkki Seppala has written Ocaml bindings for libev, to be found at
3451	L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>.	3648	L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>.
3452		3649
3453	=item Lua	3650	=item Lua
3454		3651
3455	Brian Maher has written a partial interface to libev	3652	Brian Maher has written a partial interface to libev for lua (at the
3456	for lua (only C<ev_io> and C<ev_timer>), to be found at	3653	time of this writing, only C<ev_io> and C<ev_timer>), to be found at
3457	L<http://github.com/brimworks/lua-ev>.	3654	L<http://github.com/brimworks/lua-ev>.
3458		3655
3459	=back	3656	=back
3460		3657
3461		3658
…		…
3476	loop argument"). The C<EV_A> form is used when this is the sole argument,	3673	loop argument"). The C<EV_A> form is used when this is the sole argument,
3477	C<EV_A_> is used when other arguments are following. Example:	3674	C<EV_A_> is used when other arguments are following. Example:
3478		3675
3479	ev_unref (EV_A);	3676	ev_unref (EV_A);
3480	ev_timer_add (EV_A_ watcher);	3677	ev_timer_add (EV_A_ watcher);
3481	ev_loop (EV_A_ 0);	3678	ev_run (EV_A_ 0);
3482		3679
3483	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	3680	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
3484	which is often provided by the following macro.	3681	which is often provided by the following macro.
3485		3682
3486	=item C<EV_P>, C<EV_P_>	3683	=item C<EV_P>, C<EV_P_>
…		…
3526	}	3723	}
3527		3724
3528	ev_check check;	3725	ev_check check;
3529	ev_check_init (&check, check_cb);	3726	ev_check_init (&check, check_cb);
3530	ev_check_start (EV_DEFAULT_ &check);	3727	ev_check_start (EV_DEFAULT_ &check);
3531	ev_loop (EV_DEFAULT_ 0);	3728	ev_run (EV_DEFAULT_ 0);
3532		3729
3533	=head1 EMBEDDING	3730	=head1 EMBEDDING
3534		3731
3535	Libev can (and often is) directly embedded into host	3732	Libev can (and often is) directly embedded into host
3536	applications. Examples of applications that embed it include the Deliantra	3733	applications. Examples of applications that embed it include the Deliantra
…		…
3616	libev.m4	3813	libev.m4
3617		3814
3618	=head2 PREPROCESSOR SYMBOLS/MACROS	3815	=head2 PREPROCESSOR SYMBOLS/MACROS
3619		3816
3620	Libev can be configured via a variety of preprocessor symbols you have to	3817	Libev can be configured via a variety of preprocessor symbols you have to
3621	define before including any of its files. The default in the absence of	3818	define before including (or compiling) any of its files. The default in
3622	autoconf is documented for every option.	3819	the absence of autoconf is documented for every option.
		3820
		3821	Symbols marked with "(h)" do not change the ABI, and can have different
		3822	values when compiling libev vs. including F<ev.h>, so it is permissible
		3823	to redefine them before including F<ev.h> without breaking compatibility
		3824	to a compiled library. All other symbols change the ABI, which means all
		3825	users of libev and the libev code itself must be compiled with compatible
		3826	settings.
3623		3827
3624	=over 4	3828	=over 4
3625		3829
		3830	=item EV_COMPAT3 (h)
		3831
		3832	Backwards compatibility is a major concern for libev. This is why this
		3833	release of libev comes with wrappers for the functions and symbols that
		3834	have been renamed between libev version 3 and 4.
		3835
		3836	You can disable these wrappers (to test compatibility with future
		3837	versions) by defining C<EV_COMPAT3> to C<0> when compiling your
		3838	sources. This has the additional advantage that you can drop the C<struct>
		3839	from C<struct ev_loop> declarations, as libev will provide an C<ev_loop>
		3840	typedef in that case.
		3841
		3842	In some future version, the default for C<EV_COMPAT3> will become C<0>,
		3843	and in some even more future version the compatibility code will be
		3844	removed completely.
		3845
3626	=item EV_STANDALONE	3846	=item EV_STANDALONE (h)
3627		3847
3628	Must always be C<1> if you do not use autoconf configuration, which	3848	Must always be C<1> if you do not use autoconf configuration, which
3629	keeps libev from including F<config.h>, and it also defines dummy	3849	keeps libev from including F<config.h>, and it also defines dummy
3630	implementations for some libevent functions (such as logging, which is not	3850	implementations for some libevent functions (such as logging, which is not
3631	supported). It will also not define any of the structs usually found in	3851	supported). It will also not define any of the structs usually found in
…		…
3781	as well as for signal and thread safety in C<ev_async> watchers.	4001	as well as for signal and thread safety in C<ev_async> watchers.
3782		4002
3783	In the absence of this define, libev will use C<sig_atomic_t volatile>	4003	In the absence of this define, libev will use C<sig_atomic_t volatile>
3784	(from F<signal.h>), which is usually good enough on most platforms.	4004	(from F<signal.h>), which is usually good enough on most platforms.
3785		4005
3786	=item EV_H	4006	=item EV_H (h)
3787		4007
3788	The name of the F<ev.h> header file used to include it. The default if	4008	The name of the F<ev.h> header file used to include it. The default if
3789	undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be	4009	undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be
3790	used to virtually rename the F<ev.h> header file in case of conflicts.	4010	used to virtually rename the F<ev.h> header file in case of conflicts.
3791		4011
3792	=item EV_CONFIG_H	4012	=item EV_CONFIG_H (h)
3793		4013
3794	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override	4014	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override
3795	F<ev.c>'s idea of where to find the F<config.h> file, similarly to	4015	F<ev.c>'s idea of where to find the F<config.h> file, similarly to
3796	C<EV_H>, above.	4016	C<EV_H>, above.
3797		4017
3798	=item EV_EVENT_H	4018	=item EV_EVENT_H (h)
3799		4019
3800	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea	4020	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea
3801	of how the F<event.h> header can be found, the default is C<"event.h">.	4021	of how the F<event.h> header can be found, the default is C<"event.h">.
3802		4022
3803	=item EV_PROTOTYPES	4023	=item EV_PROTOTYPES (h)
3804		4024
3805	If defined to be C<0>, then F<ev.h> will not define any function	4025	If defined to be C<0>, then F<ev.h> will not define any function
3806	prototypes, but still define all the structs and other symbols. This is	4026	prototypes, but still define all the structs and other symbols. This is
3807	occasionally useful if you want to provide your own wrapper functions	4027	occasionally useful if you want to provide your own wrapper functions
3808	around libev functions.	4028	around libev functions.
…		…
3830	fine.	4050	fine.
3831		4051
3832	If your embedding application does not need any priorities, defining these	4052	If your embedding application does not need any priorities, defining these
3833	both to C<0> will save some memory and CPU.	4053	both to C<0> will save some memory and CPU.
3834		4054
3835	=item EV_PERIODIC_ENABLE	4055	=item EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE,
		4056	EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE,
		4057	EV_ASYNC_ENABLE, EV_CHILD_ENABLE.
3836		4058
3837	If undefined or defined to be C<1>, then periodic timers are supported. If	4059	If undefined or defined to be C<1> (and the platform supports it), then
3838	defined to be C<0>, then they are not. Disabling them saves a few kB of	4060	the respective watcher type is supported. If defined to be C<0>, then it
3839	code.	4061	is not. Disabling watcher types mainly saves code size.
3840		4062
3841	=item EV_IDLE_ENABLE	4063	=item EV_FEATURES
3842
3843	If undefined or defined to be C<1>, then idle watchers are supported. If
3844	defined to be C<0>, then they are not. Disabling them saves a few kB of
3845	code.
3846
3847	=item EV_EMBED_ENABLE
3848
3849	If undefined or defined to be C<1>, then embed watchers are supported. If
3850	defined to be C<0>, then they are not. Embed watchers rely on most other
3851	watcher types, which therefore must not be disabled.
3852
3853	=item EV_STAT_ENABLE
3854
3855	If undefined or defined to be C<1>, then stat watchers are supported. If
3856	defined to be C<0>, then they are not.
3857
3858	=item EV_FORK_ENABLE
3859
3860	If undefined or defined to be C<1>, then fork watchers are supported. If
3861	defined to be C<0>, then they are not.
3862
3863	=item EV_ASYNC_ENABLE
3864
3865	If undefined or defined to be C<1>, then async watchers are supported. If
3866	defined to be C<0>, then they are not.
3867
3868	=item EV_MINIMAL
3869		4064
3870	If you need to shave off some kilobytes of code at the expense of some	4065	If you need to shave off some kilobytes of code at the expense of some
3871	speed (but with the full API), define this symbol to C<1>. Currently this	4066	speed (but with the full API), you can define this symbol to request
3872	is used to override some inlining decisions, saves roughly 30% code size	4067	certain subsets of functionality. The default is to enable all features
3873	on amd64. It also selects a much smaller 2-heap for timer management over	4068	that can be enabled on the platform.
3874	the default 4-heap.
3875		4069
3876	You can save even more by disabling watcher types you do not need	4070	A typical way to use this symbol is to define it to C<0> (or to a bitset
3877	and setting C<EV_MAXPRI> == C<EV_MINPRI>. Also, disabling C<assert>	4071	with some broad features you want) and then selectively re-enable
3878	(C<-DNDEBUG>) will usually reduce code size a lot.	4072	additional parts you want, for example if you want everything minimal,
		4073	but multiple event loop support, async and child watchers and the poll
		4074	backend, use this:
3879		4075
3880	Defining C<EV_MINIMAL> to C<2> will additionally reduce the core API to	4076	#define EV_FEATURES 0
3881	provide a bare-bones event library. See C<ev.h> for details on what parts	4077	#define EV_MULTIPLICITY 1
3882	of the API are still available, and do not complain if this subset changes	4078	#define EV_USE_POLL 1
3883	over time.	4079	#define EV_CHILD_ENABLE 1
		4080	#define EV_ASYNC_ENABLE 1
		4081
		4082	The actual value is a bitset, it can be a combination of the following
		4083	values:
		4084
		4085	=over 4
		4086
		4087	=item C<1> - faster/larger code
		4088
		4089	Use larger code to speed up some operations.
		4090
		4091	Currently this is used to override some inlining decisions (enlarging the
		4092	code size by roughly 30% on amd64).
		4093
		4094	When optimising for size, use of compiler flags such as C<-Os> with
		4095	gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of
		4096	assertions.
		4097
		4098	=item C<2> - faster/larger data structures
		4099
		4100	Replaces the small 2-heap for timer management by a faster 4-heap, larger
		4101	hash table sizes and so on. This will usually further increase code size
		4102	and can additionally have an effect on the size of data structures at
		4103	runtime.
		4104
		4105	=item C<4> - full API configuration
		4106
		4107	This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and
		4108	enables multiplicity (C<EV_MULTIPLICITY>=1).
		4109
		4110	=item C<8> - full API
		4111
		4112	This enables a lot of the "lesser used" API functions. See C<ev.h> for
		4113	details on which parts of the API are still available without this
		4114	feature, and do not complain if this subset changes over time.
		4115
		4116	=item C<16> - enable all optional watcher types
		4117
		4118	Enables all optional watcher types. If you want to selectively enable
		4119	only some watcher types other than I/O and timers (e.g. prepare,
		4120	embed, async, child...) you can enable them manually by defining
		4121	C<EV_watchertype_ENABLE> to C<1> instead.
		4122
		4123	=item C<32> - enable all backends
		4124
		4125	This enables all backends - without this feature, you need to enable at
		4126	least one backend manually (C<EV_USE_SELECT> is a good choice).
		4127
		4128	=item C<64> - enable OS-specific "helper" APIs
		4129
		4130	Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by
		4131	default.
		4132
		4133	=back
		4134
		4135	Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0>
		4136	reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb
		4137	code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O
		4138	watchers, timers and monotonic clock support.
		4139
		4140	With an intelligent-enough linker (gcc+binutils are intelligent enough
		4141	when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by
		4142	your program might be left out as well - a binary starting a timer and an
		4143	I/O watcher then might come out at only 5Kb.
		4144
		4145	=item EV_AVOID_STDIO
		4146
		4147	If this is set to C<1> at compiletime, then libev will avoid using stdio
		4148	functions (printf, scanf, perror etc.). This will increase the code size
		4149	somewhat, but if your program doesn't otherwise depend on stdio and your
		4150	libc allows it, this avoids linking in the stdio library which is quite
		4151	big.
		4152
		4153	Note that error messages might become less precise when this option is
		4154	enabled.
3884		4155
3885	=item EV_NSIG	4156	=item EV_NSIG
3886		4157
3887	The highest supported signal number, +1 (or, the number of	4158	The highest supported signal number, +1 (or, the number of
3888	signals): Normally, libev tries to deduce the maximum number of signals	4159	signals): Normally, libev tries to deduce the maximum number of signals
3889	automatically, but sometimes this fails, in which case it can be	4160	automatically, but sometimes this fails, in which case it can be
3890	specified. Also, using a lower number than detected (C<32> should be	4161	specified. Also, using a lower number than detected (C<32> should be
3891	good for about any system in existance) can save some memory, as libev	4162	good for about any system in existence) can save some memory, as libev
3892	statically allocates some 12-24 bytes per signal number.	4163	statically allocates some 12-24 bytes per signal number.
3893		4164
3894	=item EV_PID_HASHSIZE	4165	=item EV_PID_HASHSIZE
3895		4166
3896	C<ev_child> watchers use a small hash table to distribute workload by	4167	C<ev_child> watchers use a small hash table to distribute workload by
3897	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more	4168	pid. The default size is C<16> (or C<1> with C<EV_FEATURES> disabled),
3898	than enough. If you need to manage thousands of children you might want to	4169	usually more than enough. If you need to manage thousands of children you
3899	increase this value (I<must> be a power of two).	4170	might want to increase this value (I<must> be a power of two).
3900		4171
3901	=item EV_INOTIFY_HASHSIZE	4172	=item EV_INOTIFY_HASHSIZE
3902		4173
3903	C<ev_stat> watchers use a small hash table to distribute workload by	4174	C<ev_stat> watchers use a small hash table to distribute workload by
3904	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),	4175	inotify watch id. The default size is C<16> (or C<1> with C<EV_FEATURES>
3905	usually more than enough. If you need to manage thousands of C<ev_stat>	4176	disabled), usually more than enough. If you need to manage thousands of
3906	watchers you might want to increase this value (I<must> be a power of	4177	C<ev_stat> watchers you might want to increase this value (I<must> be a
3907	two).	4178	power of two).
3908		4179
3909	=item EV_USE_4HEAP	4180	=item EV_USE_4HEAP
3910		4181
3911	Heaps are not very cache-efficient. To improve the cache-efficiency of the	4182	Heaps are not very cache-efficient. To improve the cache-efficiency of the
3912	timer and periodics heaps, libev uses a 4-heap when this symbol is defined	4183	timer and periodics heaps, libev uses a 4-heap when this symbol is defined
3913	to C<1>. The 4-heap uses more complicated (longer) code but has noticeably	4184	to C<1>. The 4-heap uses more complicated (longer) code but has noticeably
3914	faster performance with many (thousands) of watchers.	4185	faster performance with many (thousands) of watchers.
3915		4186
3916	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>	4187	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3917	(disabled).	4188	will be C<0>.
3918		4189
3919	=item EV_HEAP_CACHE_AT	4190	=item EV_HEAP_CACHE_AT
3920		4191
3921	Heaps are not very cache-efficient. To improve the cache-efficiency of the	4192	Heaps are not very cache-efficient. To improve the cache-efficiency of the
3922	timer and periodics heaps, libev can cache the timestamp (I<at>) within	4193	timer and periodics heaps, libev can cache the timestamp (I<at>) within
3923	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),	4194	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),
3924	which uses 8-12 bytes more per watcher and a few hundred bytes more code,	4195	which uses 8-12 bytes more per watcher and a few hundred bytes more code,
3925	but avoids random read accesses on heap changes. This improves performance	4196	but avoids random read accesses on heap changes. This improves performance
3926	noticeably with many (hundreds) of watchers.	4197	noticeably with many (hundreds) of watchers.
3927		4198
3928	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>	4199	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3929	(disabled).	4200	will be C<0>.
3930		4201
3931	=item EV_VERIFY	4202	=item EV_VERIFY
3932		4203
3933	Controls how much internal verification (see C<ev_loop_verify ()>) will	4204	Controls how much internal verification (see C<ev_verify ()>) will
3934	be done: If set to C<0>, no internal verification code will be compiled	4205	be done: If set to C<0>, no internal verification code will be compiled
3935	in. If set to C<1>, then verification code will be compiled in, but not	4206	in. If set to C<1>, then verification code will be compiled in, but not
3936	called. If set to C<2>, then the internal verification code will be	4207	called. If set to C<2>, then the internal verification code will be
3937	called once per loop, which can slow down libev. If set to C<3>, then the	4208	called once per loop, which can slow down libev. If set to C<3>, then the
3938	verification code will be called very frequently, which will slow down	4209	verification code will be called very frequently, which will slow down
3939	libev considerably.	4210	libev considerably.
3940		4211
3941	The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be	4212	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3942	C<0>.	4213	will be C<0>.
3943		4214
3944	=item EV_COMMON	4215	=item EV_COMMON
3945		4216
3946	By default, all watchers have a C<void *data> member. By redefining	4217	By default, all watchers have a C<void *data> member. By redefining
3947	this macro to a something else you can include more and other types of	4218	this macro to something else you can include more and other types of
3948	members. You have to define it each time you include one of the files,	4219	members. You have to define it each time you include one of the files,
3949	though, and it must be identical each time.	4220	though, and it must be identical each time.
3950		4221
3951	For example, the perl EV module uses something like this:	4222	For example, the perl EV module uses something like this:
3952		4223
…		…
4005	file.	4276	file.
4006		4277
4007	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	4278	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
4008	that everybody includes and which overrides some configure choices:	4279	that everybody includes and which overrides some configure choices:
4009		4280
4010	#define EV_MINIMAL 1	4281	#define EV_FEATURES 8
4011	#define EV_USE_POLL 0	4282	#define EV_USE_SELECT 1
4012	#define EV_MULTIPLICITY 0
4013	#define EV_PERIODIC_ENABLE 0	4283	#define EV_PREPARE_ENABLE 1
		4284	#define EV_IDLE_ENABLE 1
4014	#define EV_STAT_ENABLE 0	4285	#define EV_SIGNAL_ENABLE 1
4015	#define EV_FORK_ENABLE 0	4286	#define EV_CHILD_ENABLE 1
		4287	#define EV_USE_STDEXCEPT 0
4016	#define EV_CONFIG_H <config.h>	4288	#define EV_CONFIG_H <config.h>
4017	#define EV_MINPRI 0
4018	#define EV_MAXPRI 0
4019		4289
4020	#include "ev++.h"	4290	#include "ev++.h"
4021		4291
4022	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	4292	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
4023		4293
…		…
4154	userdata *u = ev_userdata (EV_A);	4424	userdata *u = ev_userdata (EV_A);
4155	pthread_mutex_lock (&u->lock);	4425	pthread_mutex_lock (&u->lock);
4156	}	4426	}
4157		4427
4158	The event loop thread first acquires the mutex, and then jumps straight	4428	The event loop thread first acquires the mutex, and then jumps straight
4159	into C<ev_loop>:	4429	into C<ev_run>:
4160		4430
4161	void *	4431	void *
4162	l_run (void *thr_arg)	4432	l_run (void *thr_arg)
4163	{	4433	{
4164	struct ev_loop *loop = (struct ev_loop *)thr_arg;	4434	struct ev_loop *loop = (struct ev_loop *)thr_arg;
4165		4435
4166	l_acquire (EV_A);	4436	l_acquire (EV_A);
4167	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);	4437	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
4168	ev_loop (EV_A_ 0);	4438	ev_run (EV_A_ 0);
4169	l_release (EV_A);	4439	l_release (EV_A);
4170		4440
4171	return 0;	4441	return 0;
4172	}	4442	}
4173		4443
…		…
4225		4495
4226	=head3 COROUTINES	4496	=head3 COROUTINES
4227		4497
4228	Libev is very accommodating to coroutines ("cooperative threads"):	4498	Libev is very accommodating to coroutines ("cooperative threads"):
4229	libev fully supports nesting calls to its functions from different	4499	libev fully supports nesting calls to its functions from different
4230	coroutines (e.g. you can call C<ev_loop> on the same loop from two	4500	coroutines (e.g. you can call C<ev_run> on the same loop from two
4231	different coroutines, and switch freely between both coroutines running	4501	different coroutines, and switch freely between both coroutines running
4232	the loop, as long as you don't confuse yourself). The only exception is	4502	the loop, as long as you don't confuse yourself). The only exception is
4233	that you must not do this from C<ev_periodic> reschedule callbacks.	4503	that you must not do this from C<ev_periodic> reschedule callbacks.
4234		4504
4235	Care has been taken to ensure that libev does not keep local state inside	4505	Care has been taken to ensure that libev does not keep local state inside
4236	C<ev_loop>, and other calls do not usually allow for coroutine switches as	4506	C<ev_run>, and other calls do not usually allow for coroutine switches as
4237	they do not call any callbacks.	4507	they do not call any callbacks.
4238		4508
4239	=head2 COMPILER WARNINGS	4509	=head2 COMPILER WARNINGS
4240		4510
4241	Depending on your compiler and compiler settings, you might get no or a	4511	Depending on your compiler and compiler settings, you might get no or a
…		…
4252	maintainable.	4522	maintainable.
4253		4523
4254	And of course, some compiler warnings are just plain stupid, or simply	4524	And of course, some compiler warnings are just plain stupid, or simply
4255	wrong (because they don't actually warn about the condition their message	4525	wrong (because they don't actually warn about the condition their message
4256	seems to warn about). For example, certain older gcc versions had some	4526	seems to warn about). For example, certain older gcc versions had some
4257	warnings that resulted an extreme number of false positives. These have	4527	warnings that resulted in an extreme number of false positives. These have
4258	been fixed, but some people still insist on making code warn-free with	4528	been fixed, but some people still insist on making code warn-free with
4259	such buggy versions.	4529	such buggy versions.
4260		4530
4261	While libev is written to generate as few warnings as possible,	4531	While libev is written to generate as few warnings as possible,
4262	"warn-free" code is not a goal, and it is recommended not to build libev	4532	"warn-free" code is not a goal, and it is recommended not to build libev
…		…
4298	I suggest using suppression lists.	4568	I suggest using suppression lists.
4299		4569
4300		4570
4301	=head1 PORTABILITY NOTES	4571	=head1 PORTABILITY NOTES
4302		4572
		4573	=head2 GNU/LINUX 32 BIT LIMITATIONS
		4574
		4575	GNU/Linux is the only common platform that supports 64 bit file/large file
		4576	interfaces but I<disables> them by default.
		4577
		4578	That means that libev compiled in the default environment doesn't support
		4579	files larger than 2GiB or so, which mainly affects C<ev_stat> watchers.
		4580
		4581	Unfortunately, many programs try to work around this GNU/Linux issue
		4582	by enabling the large file API, which makes them incompatible with the
		4583	standard libev compiled for their system.
		4584
		4585	Likewise, libev cannot enable the large file API itself as this would
		4586	suddenly make it incompatible to the default compile time environment,
		4587	i.e. all programs not using special compile switches.
		4588
		4589	=head2 OS/X AND DARWIN BUGS
		4590
		4591	The whole thing is a bug if you ask me - basically any system interface
		4592	you touch is broken, whether it is locales, poll, kqueue or even the
		4593	OpenGL drivers.
		4594
		4595	=head3 C<kqueue> is buggy
		4596
		4597	The kqueue syscall is broken in all known versions - most versions support
		4598	only sockets, many support pipes.
		4599
		4600	Libev tries to work around this by not using C<kqueue> by default on this
		4601	rotten platform, but of course you can still ask for it when creating a
		4602	loop - embedding a socket-only kqueue loop into a select-based one is
		4603	probably going to work well.
		4604
		4605	=head3 C<poll> is buggy
		4606
		4607	Instead of fixing C<kqueue>, Apple replaced their (working) C<poll>
		4608	implementation by something calling C<kqueue> internally around the 10.5.6
		4609	release, so now C<kqueue> I<and> C<poll> are broken.
		4610
		4611	Libev tries to work around this by not using C<poll> by default on
		4612	this rotten platform, but of course you can still ask for it when creating
		4613	a loop.
		4614
		4615	=head3 C<select> is buggy
		4616
		4617	All that's left is C<select>, and of course Apple found a way to fuck this
		4618	one up as well: On OS/X, C<select> actively limits the number of file
		4619	descriptors you can pass in to 1024 - your program suddenly crashes when
		4620	you use more.
		4621
		4622	There is an undocumented "workaround" for this - defining
		4623	C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should>
		4624	work on OS/X.
		4625
		4626	=head2 SOLARIS PROBLEMS AND WORKAROUNDS
		4627
		4628	=head3 C<errno> reentrancy
		4629
		4630	The default compile environment on Solaris is unfortunately so
		4631	thread-unsafe that you can't even use components/libraries compiled
		4632	without C<-D_REENTRANT> in a threaded program, which, of course, isn't
		4633	defined by default. A valid, if stupid, implementation choice.
		4634
		4635	If you want to use libev in threaded environments you have to make sure
		4636	it's compiled with C<_REENTRANT> defined.
		4637
		4638	=head3 Event port backend
		4639
		4640	The scalable event interface for Solaris is called "event
		4641	ports". Unfortunately, this mechanism is very buggy in all major
		4642	releases. If you run into high CPU usage, your program freezes or you get
		4643	a large number of spurious wakeups, make sure you have all the relevant
		4644	and latest kernel patches applied. No, I don't know which ones, but there
		4645	are multiple ones to apply, and afterwards, event ports actually work
		4646	great.
		4647
		4648	If you can't get it to work, you can try running the program by setting
		4649	the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and
		4650	C<select> backends.
		4651
		4652	=head2 AIX POLL BUG
		4653
		4654	AIX unfortunately has a broken C<poll.h> header. Libev works around
		4655	this by trying to avoid the poll backend altogether (i.e. it's not even
		4656	compiled in), which normally isn't a big problem as C<select> works fine
		4657	with large bitsets on AIX, and AIX is dead anyway.
		4658
4303	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS	4659	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
		4660
		4661	=head3 General issues
4304		4662
4305	Win32 doesn't support any of the standards (e.g. POSIX) that libev	4663	Win32 doesn't support any of the standards (e.g. POSIX) that libev
4306	requires, and its I/O model is fundamentally incompatible with the POSIX	4664	requires, and its I/O model is fundamentally incompatible with the POSIX
4307	model. Libev still offers limited functionality on this platform in	4665	model. Libev still offers limited functionality on this platform in
4308	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	4666	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
4309	descriptors. This only applies when using Win32 natively, not when using	4667	descriptors. This only applies when using Win32 natively, not when using
4310	e.g. cygwin.	4668	e.g. cygwin. Actually, it only applies to the microsofts own compilers,
		4669	as every compielr comes with a slightly differently broken/incompatible
		4670	environment.
4311		4671
4312	Lifting these limitations would basically require the full	4672	Lifting these limitations would basically require the full
4313	re-implementation of the I/O system. If you are into these kinds of	4673	re-implementation of the I/O system. If you are into this kind of thing,
4314	things, then note that glib does exactly that for you in a very portable	4674	then note that glib does exactly that for you in a very portable way (note
4315	way (note also that glib is the slowest event library known to man).	4675	also that glib is the slowest event library known to man).
4316		4676
4317	There is no supported compilation method available on windows except	4677	There is no supported compilation method available on windows except
4318	embedding it into other applications.	4678	embedding it into other applications.
4319		4679
4320	Sensible signal handling is officially unsupported by Microsoft - libev	4680	Sensible signal handling is officially unsupported by Microsoft - libev
…		…
4348	you do I<not> compile the F<ev.c> or any other embedded source files!):	4708	you do I<not> compile the F<ev.c> or any other embedded source files!):
4349		4709
4350	#include "evwrap.h"	4710	#include "evwrap.h"
4351	#include "ev.c"	4711	#include "ev.c"
4352		4712
4353	=over 4
4354
4355	=item The winsocket select function	4713	=head3 The winsocket C<select> function
4356		4714
4357	The winsocket C<select> function doesn't follow POSIX in that it	4715	The winsocket C<select> function doesn't follow POSIX in that it
4358	requires socket I<handles> and not socket I<file descriptors> (it is	4716	requires socket I<handles> and not socket I<file descriptors> (it is
4359	also extremely buggy). This makes select very inefficient, and also	4717	also extremely buggy). This makes select very inefficient, and also
4360	requires a mapping from file descriptors to socket handles (the Microsoft	4718	requires a mapping from file descriptors to socket handles (the Microsoft
…		…
4369	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */	4727	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
4370		4728
4371	Note that winsockets handling of fd sets is O(n), so you can easily get a	4729	Note that winsockets handling of fd sets is O(n), so you can easily get a
4372	complexity in the O(n²) range when using win32.	4730	complexity in the O(n²) range when using win32.
4373		4731
4374	=item Limited number of file descriptors	4732	=head3 Limited number of file descriptors
4375		4733
4376	Windows has numerous arbitrary (and low) limits on things.	4734	Windows has numerous arbitrary (and low) limits on things.
4377		4735
4378	Early versions of winsocket's select only supported waiting for a maximum	4736	Early versions of winsocket's select only supported waiting for a maximum
4379	of C<64> handles (probably owning to the fact that all windows kernels	4737	of C<64> handles (probably owning to the fact that all windows kernels
…		…
4394	runtime libraries. This might get you to about C<512> or C<2048> sockets	4752	runtime libraries. This might get you to about C<512> or C<2048> sockets
4395	(depending on windows version and/or the phase of the moon). To get more,	4753	(depending on windows version and/or the phase of the moon). To get more,
4396	you need to wrap all I/O functions and provide your own fd management, but	4754	you need to wrap all I/O functions and provide your own fd management, but
4397	the cost of calling select (O(n²)) will likely make this unworkable.	4755	the cost of calling select (O(n²)) will likely make this unworkable.
4398		4756
4399	=back
4400
4401	=head2 PORTABILITY REQUIREMENTS	4757	=head2 PORTABILITY REQUIREMENTS
4402		4758
4403	In addition to a working ISO-C implementation and of course the	4759	In addition to a working ISO-C implementation and of course the
4404	backend-specific APIs, libev relies on a few additional extensions:	4760	backend-specific APIs, libev relies on a few additional extensions:
4405		4761
…		…
4411	Libev assumes not only that all watcher pointers have the same internal	4767	Libev assumes not only that all watcher pointers have the same internal
4412	structure (guaranteed by POSIX but not by ISO C for example), but it also	4768	structure (guaranteed by POSIX but not by ISO C for example), but it also
4413	assumes that the same (machine) code can be used to call any watcher	4769	assumes that the same (machine) code can be used to call any watcher
4414	callback: The watcher callbacks have different type signatures, but libev	4770	callback: The watcher callbacks have different type signatures, but libev
4415	calls them using an C<ev_watcher *> internally.	4771	calls them using an C<ev_watcher *> internally.
		4772
		4773	=item pointer accesses must be thread-atomic
		4774
		4775	Accessing a pointer value must be atomic, it must both be readable and
		4776	writable in one piece - this is the case on all current architectures.
4416		4777
4417	=item C<sig_atomic_t volatile> must be thread-atomic as well	4778	=item C<sig_atomic_t volatile> must be thread-atomic as well
4418		4779
4419	The type C<sig_atomic_t volatile> (or whatever is defined as	4780	The type C<sig_atomic_t volatile> (or whatever is defined as
4420	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different	4781	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different
…		…
4443	watchers.	4804	watchers.
4444		4805
4445	=item C<double> must hold a time value in seconds with enough accuracy	4806	=item C<double> must hold a time value in seconds with enough accuracy
4446		4807
4447	The type C<double> is used to represent timestamps. It is required to	4808	The type C<double> is used to represent timestamps. It is required to
4448	have at least 51 bits of mantissa (and 9 bits of exponent), which is good	4809	have at least 51 bits of mantissa (and 9 bits of exponent), which is
4449	enough for at least into the year 4000. This requirement is fulfilled by	4810	good enough for at least into the year 4000 with millisecond accuracy
		4811	(the design goal for libev). This requirement is overfulfilled by
4450	implementations implementing IEEE 754, which is basically all existing	4812	implementations using IEEE 754, which is basically all existing ones. With
4451	ones. With IEEE 754 doubles, you get microsecond accuracy until at least	4813	IEEE 754 doubles, you get microsecond accuracy until at least 2200.
4452	2200.
4453		4814
4454	=back	4815	=back
4455		4816
4456	If you know of other additional requirements drop me a note.	4817	If you know of other additional requirements drop me a note.
4457		4818
…		…
4525	involves iterating over all running async watchers or all signal numbers.	4886	involves iterating over all running async watchers or all signal numbers.
4526		4887
4527	=back	4888	=back
4528		4889
4529		4890
		4891	=head1 PORTING FROM LIBEV 3.X TO 4.X
		4892
		4893	The major version 4 introduced some incompatible changes to the API.
		4894
		4895	At the moment, the C<ev.h> header file provides compatibility definitions
		4896	for all changes, so most programs should still compile. The compatibility
		4897	layer might be removed in later versions of libev, so better update to the
		4898	new API early than late.
		4899
		4900	=over 4
		4901
		4902	=item C<EV_COMPAT3> backwards compatibility mechanism
		4903
		4904	The backward compatibility mechanism can be controlled by
		4905	C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING>
		4906	section.
		4907
		4908	=item C<ev_default_destroy> and C<ev_default_fork> have been removed
		4909
		4910	These calls can be replaced easily by their C<ev_loop_xxx> counterparts:
		4911
		4912	ev_loop_destroy (EV_DEFAULT_UC);
		4913	ev_loop_fork (EV_DEFAULT);
		4914
		4915	=item function/symbol renames
		4916
		4917	A number of functions and symbols have been renamed:
		4918
		4919	ev_loop => ev_run
		4920	EVLOOP_NONBLOCK => EVRUN_NOWAIT
		4921	EVLOOP_ONESHOT => EVRUN_ONCE
		4922
		4923	ev_unloop => ev_break
		4924	EVUNLOOP_CANCEL => EVBREAK_CANCEL
		4925	EVUNLOOP_ONE => EVBREAK_ONE
		4926	EVUNLOOP_ALL => EVBREAK_ALL
		4927
		4928	EV_TIMEOUT => EV_TIMER
		4929
		4930	ev_loop_count => ev_iteration
		4931	ev_loop_depth => ev_depth
		4932	ev_loop_verify => ev_verify
		4933
		4934	Most functions working on C<struct ev_loop> objects don't have an
		4935	C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and
		4936	associated constants have been renamed to not collide with the C<struct
		4937	ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme
		4938	as all other watcher types. Note that C<ev_loop_fork> is still called
		4939	C<ev_loop_fork> because it would otherwise clash with the C<ev_fork>
		4940	typedef.
		4941
		4942	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>
		4943
		4944	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different
		4945	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile
		4946	and work, but the library code will of course be larger.
		4947
		4948	=back
		4949
		4950
4530	=head1 GLOSSARY	4951	=head1 GLOSSARY
4531		4952
4532	=over 4	4953	=over 4
4533		4954
4534	=item active	4955	=item active
4535		4956
4536	A watcher is active as long as it has been started (has been attached to	4957	A watcher is active as long as it has been started and not yet stopped.
4537	an event loop) but not yet stopped (disassociated from the event loop).	4958	See L<WATCHER STATES> for details.
4538		4959
4539	=item application	4960	=item application
4540		4961
4541	In this document, an application is whatever is using libev.	4962	In this document, an application is whatever is using libev.
		4963
		4964	=item backend
		4965
		4966	The part of the code dealing with the operating system interfaces.
4542		4967
4543	=item callback	4968	=item callback
4544		4969
4545	The address of a function that is called when some event has been	4970	The address of a function that is called when some event has been
4546	detected. Callbacks are being passed the event loop, the watcher that	4971	detected. Callbacks are being passed the event loop, the watcher that
4547	received the event, and the actual event bitset.	4972	received the event, and the actual event bitset.
4548		4973
4549	=item callback invocation	4974	=item callback/watcher invocation
4550		4975
4551	The act of calling the callback associated with a watcher.	4976	The act of calling the callback associated with a watcher.
4552		4977
4553	=item event	4978	=item event
4554		4979
4555	A change of state of some external event, such as data now being available	4980	A change of state of some external event, such as data now being available
4556	for reading on a file descriptor, time having passed or simply not having	4981	for reading on a file descriptor, time having passed or simply not having
4557	any other events happening anymore.	4982	any other events happening anymore.
4558		4983
4559	In libev, events are represented as single bits (such as C<EV_READ> or	4984	In libev, events are represented as single bits (such as C<EV_READ> or
4560	C<EV_TIMEOUT>).	4985	C<EV_TIMER>).
4561		4986
4562	=item event library	4987	=item event library
4563		4988
4564	A software package implementing an event model and loop.	4989	A software package implementing an event model and loop.
4565		4990
…		…
4573	The model used to describe how an event loop handles and processes	4998	The model used to describe how an event loop handles and processes
4574	watchers and events.	4999	watchers and events.
4575		5000
4576	=item pending	5001	=item pending
4577		5002
4578	A watcher is pending as soon as the corresponding event has been detected,	5003	A watcher is pending as soon as the corresponding event has been
4579	and stops being pending as soon as the watcher will be invoked or its	5004	detected. See L<WATCHER STATES> for details.
4580	pending status is explicitly cleared by the application.
4581
4582	A watcher can be pending, but not active. Stopping a watcher also clears
4583	its pending status.
4584		5005
4585	=item real time	5006	=item real time
4586		5007
4587	The physical time that is observed. It is apparently strictly monotonic :)	5008	The physical time that is observed. It is apparently strictly monotonic :)
4588		5009
…		…
4595	=item watcher	5016	=item watcher
4596		5017
4597	A data structure that describes interest in certain events. Watchers need	5018	A data structure that describes interest in certain events. Watchers need
4598	to be started (attached to an event loop) before they can receive events.	5019	to be started (attached to an event loop) before they can receive events.
4599		5020
4600	=item watcher invocation
4601
4602	The act of calling the callback associated with a watcher.
4603
4604	=back	5021	=back
4605		5022
4606	=head1 AUTHOR	5023	=head1 AUTHOR
4607		5024
4608	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson.	5025	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael
		5026	Magnusson and Emanuele Giaquinta.
4609		5027

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