ViewVC Help

View File | Revision Log | Show Annotations | Download File

/cvs/libev/ev.pod

Comparing libev/ev.pod (file contents):
Revision 1.290 by root, Tue Mar 16 18:03:01 2010 UTC vs.
Revision 1.342 by root, Wed Nov 10 13:16:44 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 it 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. It can also simplify signal	416	it possible to get the queued signal data. It can also simplify signal
381	handling with threads, as long as you properly block signals in your	417	handling with threads, as long as you properly block signals in your
382	threads that are not interested in handling them.	418	threads that are not interested in handling them.
383		419
…		…
427	epoll scales either O(1) or O(active_fds).	463	epoll scales either O(1) or O(active_fds).
428		464
429	The epoll mechanism deserves honorable mention as the most misdesigned	465	The epoll mechanism deserves honorable mention as the most misdesigned
430	of the more advanced event mechanisms: mere annoyances include silently	466	of the more advanced event mechanisms: mere annoyances include silently
431	dropping file descriptors, requiring a system call per change per file	467	dropping file descriptors, requiring a system call per change per file
432	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
433	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
434	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
435	take considerable time (one syscall per file descriptor) and is of course	473	set, which can take considerable time (one syscall per file descriptor)
436	hard to detect.	474	and is of course hard to detect.
437		475
438	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
439	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
440	I<different> file descriptors (even already closed ones, so one cannot	478	I<different> file descriptors (even already closed ones, so one cannot
441	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
442	on SMP systems). Libev tries to counter these spurious notifications by	480	on SMP systems). Libev tries to counter these spurious notifications by
443	employing an additional generation counter and comparing that against the	481	employing an additional generation counter and comparing that against the
444	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.
445		487
446	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
447	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
448	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
449	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
…		…
547	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,
548	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
549	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
550	()> will be tried.	592	()> will be tried.
551		593
552	Example: This is the most typical usage.
553
554	if (!ev_default_loop (0))
555	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
556
557	Example: Restrict libev to the select and poll backends, and do not allow
558	environment settings to be taken into account:
559
560	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
561
562	Example: Use whatever libev has to offer, but make sure that kqueue is
563	used if available (warning, breaks stuff, best use only with your own
564	private event loop and only if you know the OS supports your types of
565	fds):
566
567	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
568
569	=item struct ev_loop *ev_loop_new (unsigned int flags)
570
571	Similar to C<ev_default_loop>, but always creates a new event loop that is
572	always distinct from the default loop.
573
574	Note that this function I<is> thread-safe, and one common way to use
575	libev with threads is indeed to create one loop per thread, and using the
576	default loop in the "main" or "initial" thread.
577
578	Example: Try to create a event loop that uses epoll and nothing else.	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 (frees all memory and kernel state etc.). None	607	Destroys an event loop object (frees all memory and kernel state
587	of the active event watchers will be stopped in the normal sense, so	608	etc.). None of the active event watchers will be stopped in the normal
588	e.g. C<ev_is_active> might still return true. It is your responsibility to	609	sense, so e.g. C<ev_is_active> might still return true. It is your
589	either stop all watchers cleanly yourself I<before> calling this function,	610	responsibility to either stop all watchers cleanly yourself I<before>
590	or cope with the fact afterwards (which is usually the easiest thing, you	611	calling this function, or cope with the fact afterwards (which is usually
591	can just ignore the watchers and/or C<free ()> them for example).	612	the easiest thing, you can just ignore the watchers and/or C<free ()> them
		613	for example).
592		614
593	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
594	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
595	as signal and child watchers) would need to be stopped manually.	617	as signal and child watchers) would need to be stopped manually.
596		618
597	In general it is not advisable to call this function except in the	619	This function is normally used on loop objects allocated by
598	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.
599	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>
600	C<ev_loop_new> and C<ev_loop_destroy>.	626	and C<ev_loop_destroy>.
601		627
602	=item ev_loop_destroy (loop)	628	=item ev_loop_fork (loop)
603		629
604	Like C<ev_default_destroy>, but destroys an event loop created by an
605	earlier call to C<ev_loop_new>.
606
607	=item ev_default_fork ()
608
609	This function sets a flag that causes subsequent C<ev_loop> iterations	630	This function sets a flag that causes subsequent C<ev_run> iterations to
610	to reinitialise the kernel state for backends that have one. Despite the	631	reinitialise the kernel state for backends that have one. Despite the
611	name, you can call it anytime, but it makes most sense after forking, in	632	name, you can call it anytime, but it makes most sense after forking, in
612	the child process (or both child and parent, but that again makes little	633	the child process. You I<must> call it (or use C<EVFLAG_FORKCHECK>) in the
613	sense). You I<must> call it in the child before using any of the libev	634	child before resuming or calling C<ev_run>.
614	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.
615		640
616	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
617	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
618	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).
619		647
620	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
621	it just in case after a fork. To make this easy, the function will fit in	649	it just in case after a fork.
622	quite nicely into a call to C<pthread_atfork>:
623		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	...
624	pthread_atfork (0, 0, ev_default_fork);	661	pthread_atfork (0, 0, post_fork_child);
625
626	=item ev_loop_fork (loop)
627
628	Like C<ev_default_fork>, but acts on an event loop created by
629	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
630	after fork that you want to re-use in the child, and how you do this is
631	entirely your own problem.
632		662
633	=item int ev_is_default_loop (loop)	663	=item int ev_is_default_loop (loop)
634		664
635	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
636	otherwise.	666	otherwise.
637		667
638	=item unsigned int ev_loop_count (loop)	668	=item unsigned int ev_iteration (loop)
639		669
640	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
641	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>
642	happily wraps around with enough iterations.	672	and happily wraps around with enough iterations.
643		673
644	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
645	"ticks" the number of loop iterations), as it roughly corresponds with	675	"ticks" the number of loop iterations), as it roughly corresponds with
646	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.
647		678
648	=item unsigned int ev_loop_depth (loop)	679	=item unsigned int ev_depth (loop)
649		680
650	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
651	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.
652		683
653	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
654	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),
655	in which case it is higher.	686	in which case it is higher.
656		687
657	Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread	688	Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread
658	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.
659		691
660	=item unsigned int ev_backend (loop)	692	=item unsigned int ev_backend (loop)
661		693
662	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
663	use.	695	use.
…		…
672		704
673	=item ev_now_update (loop)	705	=item ev_now_update (loop)
674		706
675	Establishes the current time by querying the kernel, updating the time	707	Establishes the current time by querying the kernel, updating the time
676	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
677	is usually done automatically within C<ev_loop ()>.	709	is usually done automatically within C<ev_run ()>.
678		710
679	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
680	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
681	the current time is a good idea.	713	the current time is a good idea.
682		714
…		…
684		716
685	=item ev_suspend (loop)	717	=item ev_suspend (loop)
686		718
687	=item ev_resume (loop)	719	=item ev_resume (loop)
688		720
689	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
690	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.
691		723
692	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
693	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
694	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
695	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>
…		…
697	C<ev_resume> directly afterwards to resume timer processing.	729	C<ev_resume> directly afterwards to resume timer processing.
698		730
699	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
700	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
701	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
702	occured while suspended).	734	occurred while suspended).
703		735
704	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
705	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>
706	without a previous call to C<ev_suspend>.	738	without a previous call to C<ev_suspend>.
707		739
708	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
709	event loop time (see C<ev_now_update>).	741	event loop time (see C<ev_now_update>).
710		742
711	=item ev_loop (loop, int flags)	743	=item ev_run (loop, int flags)
712		744
713	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
714	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
715	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>.
716		750
717	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
718	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.
719		754
720	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
721	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
722	finished (especially in interactive programs), but having a program	757	finished (especially in interactive programs), but having a program
723	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
724	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
725	beauty.	760	beauty.
726		761
727	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
728	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
729	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
730	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.
731		767
732	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
733	necessary) and will handle those and any already outstanding ones. It	769	necessary) and will handle those and any already outstanding ones. It
734	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
735	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
736	user-registered callback will be called), and will return after one	772	user-registered callback will be called), and will return after one
737	iteration of the loop.	773	iteration of the loop.
738		774
739	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
740	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
741	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
742	usually a better approach for this kind of thing.	778	usually a better approach for this kind of thing.
743		779
744	Here are the gory details of what C<ev_loop> does:	780	Here are the gory details of what C<ev_run> does:
745		781
		782	- Increment loop depth.
		783	- Reset the ev_break status.
746	- Before the first iteration, call any pending watchers.	784	- Before the first iteration, call any pending watchers.
		785	LOOP:
747	* If EVFLAG_FORKCHECK was used, check for a fork.	786	- If EVFLAG_FORKCHECK was used, check for a fork.
748	- 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.
749	- Queue and call all prepare watchers.	788	- Queue and call all prepare watchers.
		789	- If ev_break was called, goto FINISH.
750	- If we have been forked, detach and recreate the kernel state	790	- If we have been forked, detach and recreate the kernel state
751	as to not disturb the other process.	791	as to not disturb the other process.
752	- Update the kernel state with all outstanding changes.	792	- Update the kernel state with all outstanding changes.
753	- Update the "event loop time" (ev_now ()).	793	- Update the "event loop time" (ev_now ()).
754	- Calculate for how long to sleep or block, if at all	794	- Calculate for how long to sleep or block, if at all
755	(active idle watchers, EVLOOP_NONBLOCK or not having	795	(active idle watchers, EVRUN_NOWAIT or not having
756	any active watchers at all will result in not sleeping).	796	any active watchers at all will result in not sleeping).
757	- 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.
758	- Block the process, waiting for any events.	799	- Block the process, waiting for any events.
759	- Queue all outstanding I/O (fd) events.	800	- Queue all outstanding I/O (fd) events.
760	- 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.
761	- Queue all expired timers.	802	- Queue all expired timers.
762	- Queue all expired periodics.	803	- Queue all expired periodics.
763	- Unless any events are pending now, queue all idle watchers.	804	- Queue all idle watchers with priority higher than that of pending events.
764	- Queue all check watchers.	805	- Queue all check watchers.
765	- 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).
766	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
767	be handled here by queueing them when their watcher gets executed.	808	be handled here by queueing them when their watcher gets executed.
768	- 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
769	were used, or there are no active watchers, return, otherwise	810	were used, or there are no active watchers, goto FINISH, otherwise
770	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.
771		816
772	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
773	anymore.	818	anymore.
774		819
775	... queue jobs here, make sure they register event watchers as long	820	... queue jobs here, make sure they register event watchers as long
776	... 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..)
777	ev_loop (my_loop, 0);	822	ev_run (my_loop, 0);
778	... jobs done or somebody called unloop. yeah!	823	... jobs done or somebody called unloop. yeah!
779		824
780	=item ev_unloop (loop, how)	825	=item ev_break (loop, how)
781		826
782	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
783	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
784	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
785	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.
786		831
787	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.
788		833
789	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.
790		835
791	=item ev_ref (loop)	836	=item ev_ref (loop)
792		837
793	=item ev_unref (loop)	838	=item ev_unref (loop)
794		839
795	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
796	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
797	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.
798		843
799	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
800	unregister, but that nevertheless should not keep C<ev_loop> from	845	unregister, but that nevertheless should not keep C<ev_run> from
801	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>
802	before stopping it.	847	before stopping it.
803		848
804	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
805	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
806	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
807	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
808	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
809	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
810	before, respectively. Note also that libev might stop watchers itself	855	before, respectively. Note also that libev might stop watchers itself
811	(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>
812	in the callback).	857	in the callback).
813		858
814	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>
815	running when nothing else is active.	860	running when nothing else is active.
816		861
817	ev_signal exitsig;	862	ev_signal exitsig;
818	ev_signal_init (&exitsig, sig_cb, SIGINT);	863	ev_signal_init (&exitsig, sig_cb, SIGINT);
819	ev_signal_start (loop, &exitsig);	864	ev_signal_start (loop, &exitsig);
…		…
864	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>,
865	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
866	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
867	parallelity, then this setting will limit your transaction rate (if you	912	parallelity, then this setting will limit your transaction rate (if you
868	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,
869	then you can't do more than 100 transations per second).	914	then you can't do more than 100 transactions per second).
870		915
871	Setting the I<timeout collect interval> can improve the opportunity for	916	Setting the I<timeout collect interval> can improve the opportunity for
872	saving power, as the program will "bundle" timer callback invocations that	917	saving power, as the program will "bundle" timer callback invocations that
873	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
874	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
…		…
882	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);	927	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);
883		928
884	=item ev_invoke_pending (loop)	929	=item ev_invoke_pending (loop)
885		930
886	This call will simply invoke all pending watchers while resetting their	931	This call will simply invoke all pending watchers while resetting their
887	pending state. Normally, C<ev_loop> does this automatically when required,	932	pending state. Normally, C<ev_run> does this automatically when required,
888	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).
889		938
890	=item int ev_pending_count (loop)	939	=item int ev_pending_count (loop)
891		940
892	Returns the number of pending watchers - zero indicates that no watchers	941	Returns the number of pending watchers - zero indicates that no watchers
893	are pending.	942	are pending.
894		943
895	=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))
896		945
897	This overrides the invoke pending functionality of the loop: Instead of	946	This overrides the invoke pending functionality of the loop: Instead of
898	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
899	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
900	invoke the actual watchers inside another context (another thread etc.).	949	invoke the actual watchers inside another context (another thread etc.).
901		950
902	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
903	callback.	952	callback.
…		…
906		955
907	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
908	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
909	each call to a libev function.	958	each call to a libev function.
910		959
911	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
912	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
913	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
914	and I<acquire> callbacks on the loop.	963	I<release> and I<acquire> callbacks on the loop.
915		964
916	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
917	suspended waiting for new events, and C<acquire> is called just	966	suspended waiting for new events, and C<acquire> is called just
918	afterwards.	967	afterwards.
919		968
…		…
922		971
923	While event loop modifications are allowed between invocations of	972	While event loop modifications are allowed between invocations of
924	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
925	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
926	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
927	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
928	to take note of any changes you made.	977	to take note of any changes you made.
929		978
930	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
931	invocations of C<release> and C<acquire>.	980	invocations of C<release> and C<acquire>.
932		981
933	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
934	document.	983	document.
935		984
…		…
937		986
938	=item ev_userdata (loop)	987	=item ev_userdata (loop)
939		988
940	Set and retrieve a single C<void *> associated with a loop. When	989	Set and retrieve a single C<void *> associated with a loop. When
941	C<ev_set_userdata> has never been called, then C<ev_userdata> returns	990	C<ev_set_userdata> has never been called, then C<ev_userdata> returns
942	C<0.>	991	C<0>.
943		992
944	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,
945	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
946	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
947	any other purpose as well.	996	any other purpose as well.
948		997
949	=item ev_loop_verify (loop)	998	=item ev_verify (loop)
950		999
951	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
952	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
953	through all internal structures and checks them for validity. If anything	1002	through all internal structures and checks them for validity. If anything
954	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
…		…
965		1014
966	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
967	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
968	watchers and C<ev_io_start> for I/O watchers.	1017	watchers and C<ev_io_start> for I/O watchers.
969		1018
970	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
971	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
972	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:
973		1023
974	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)
975	{	1025	{
976	ev_io_stop (w);	1026	ev_io_stop (w);
977	ev_unloop (loop, EVUNLOOP_ALL);	1027	ev_break (loop, EVBREAK_ALL);
978	}	1028	}
979		1029
980	struct ev_loop *loop = ev_default_loop (0);	1030	struct ev_loop *loop = ev_default_loop (0);
981		1031
982	ev_io stdin_watcher;	1032	ev_io stdin_watcher;
983		1033
984	ev_init (&stdin_watcher, my_cb);	1034	ev_init (&stdin_watcher, my_cb);
985	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	1035	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
986	ev_io_start (loop, &stdin_watcher);	1036	ev_io_start (loop, &stdin_watcher);
987		1037
988	ev_loop (loop, 0);	1038	ev_run (loop, 0);
989		1039
990	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
991	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
992	stack).	1042	stack).
993		1043
994	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>
995	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).
996		1046
997	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
998	(watcher *, callback)>, which expects a callback to be provided. This	1048	*, callback)>, which expects a callback to be provided. This callback is
999	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
1000	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
1001	is readable and/or writable).	1051	and/or writable).
1002		1052
1003	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 *, ...) >>
1004	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
1005	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<<
1006	ev_TYPE_init (watcher *, callback, ...) >>.	1056	ev_TYPE_init (watcher *, callback, ...) >>.
…		…
1057		1107
1058	=item C<EV_PREPARE>	1108	=item C<EV_PREPARE>
1059		1109
1060	=item C<EV_CHECK>	1110	=item C<EV_CHECK>
1061		1111
1062	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
1063	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
1064	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
1065	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
1066	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
1067	(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
1068	C<ev_loop> from blocking).	1118	C<ev_run> from blocking).
1069		1119
1070	=item C<EV_EMBED>	1120	=item C<EV_EMBED>
1071		1121
1072	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.
1073		1123
1074	=item C<EV_FORK>	1124	=item C<EV_FORK>
1075		1125
1076	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
1077	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>).
1078		1132
1079	=item C<EV_ASYNC>	1133	=item C<EV_ASYNC>
1080		1134
1081	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>).
1082		1136
…		…
1254		1308
1255	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
1256	functions that do not need a watcher.	1310	functions that do not need a watcher.
1257		1311
1258	=back	1312	=back
1259
1260		1313
1261	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	1314	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
1262		1315
1263	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
1264	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
…		…
1320	t2_cb (EV_P_ ev_timer *w, int revents)	1373	t2_cb (EV_P_ ev_timer *w, int revents)
1321	{	1374	{
1322	struct my_biggy big = (struct my_biggy *)	1375	struct my_biggy big = (struct my_biggy *)
1323	(((char *)w) - offsetof (struct my_biggy, t2));	1376	(((char *)w) - offsetof (struct my_biggy, t2));
1324	}	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
1325		1437
1326	=head2 WATCHER PRIORITY MODELS	1438	=head2 WATCHER PRIORITY MODELS
1327		1439
1328	Many event loops support I<watcher priorities>, which are usually small	1440	Many event loops support I<watcher priorities>, which are usually small
1329	integers that influence the ordering of event callback invocation	1441	integers that influence the ordering of event callback invocation
…		…
1372		1484
1373	For example, to emulate how many other event libraries handle priorities,	1485	For example, to emulate how many other event libraries handle priorities,
1374	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
1375	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
1376	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
1377	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
1378	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
1379	workable.	1491	workable.
1380		1492
1381	Usually, however, the lock-out model implemented that way will perform	1493	Usually, however, the lock-out model implemented that way will perform
1382	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,
…		…
1396	{	1508	{
1397	// stop the I/O watcher, we received the event, but	1509	// stop the I/O watcher, we received the event, but
1398	// are not yet ready to handle it.	1510	// are not yet ready to handle it.
1399	ev_io_stop (EV_A_ w);	1511	ev_io_stop (EV_A_ w);
1400		1512
1401	// start the idle watcher to ahndle the actual event.	1513	// start the idle watcher to handle the actual event.
1402	// it will not be executed as long as other watchers	1514	// it will not be executed as long as other watchers
1403	// with the default priority are receiving events.	1515	// with the default priority are receiving events.
1404	ev_idle_start (EV_A_ &idle);	1516	ev_idle_start (EV_A_ &idle);
1405	}	1517	}
1406		1518
…		…
1460		1572
1461	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
1462	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
1463	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
1464	descriptors for which non-blocking operation makes no sense (such as	1576	descriptors for which non-blocking operation makes no sense (such as
1465	files) - libev doesn't guarentee any specific behaviour in that case.	1577	files) - libev doesn't guarantee any specific behaviour in that case.
1466		1578
1467	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
1468	receive "spurious" readiness notifications, that is your callback might	1580	receive "spurious" readiness notifications, that is your callback might
1469	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
1470	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
…		…
1538	somewhere, as that would have given you a big clue).	1650	somewhere, as that would have given you a big clue).
1539		1651
1540	=head3 The special problem of accept()ing when you can't	1652	=head3 The special problem of accept()ing when you can't
1541		1653
1542	Many implementations of the POSIX C<accept> function (for example,	1654	Many implementations of the POSIX C<accept> function (for example,
1543	found in port-2004 Linux) have the peculiar behaviour of not removing a	1655	found in post-2004 Linux) have the peculiar behaviour of not removing a
1544	connection from the pending queue in all error cases.	1656	connection from the pending queue in all error cases.
1545		1657
1546	For example, larger servers often run out of file descriptors (because	1658	For example, larger servers often run out of file descriptors (because
1547	of resource limits), causing C<accept> to fail with C<ENFILE> but not	1659	of resource limits), causing C<accept> to fail with C<ENFILE> but not
1548	rejecting the connection, leading to libev signalling readiness on	1660	rejecting the connection, leading to libev signalling readiness on
…		…
1614	...	1726	...
1615	struct ev_loop *loop = ev_default_init (0);	1727	struct ev_loop *loop = ev_default_init (0);
1616	ev_io stdin_readable;	1728	ev_io stdin_readable;
1617	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);
1618	ev_io_start (loop, &stdin_readable);	1730	ev_io_start (loop, &stdin_readable);
1619	ev_loop (loop, 0);	1731	ev_run (loop, 0);
1620		1732
1621		1733
1622	=head2 C<ev_timer> - relative and optionally repeating timeouts	1734	=head2 C<ev_timer> - relative and optionally repeating timeouts
1623		1735
1624	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
…		…
1633	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
1634	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
1635	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
1636	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
1637	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
1638	no longer true when a callback calls C<ev_loop> recursively).	1750	no longer true when a callback calls C<ev_run> recursively).
1639		1751
1640	=head3 Be smart about timeouts	1752	=head3 Be smart about timeouts
1641		1753
1642	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
1643	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,
…		…
1729	ev_tstamp timeout = last_activity + 60.;	1841	ev_tstamp timeout = last_activity + 60.;
1730		1842
1731	// 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
1732	if (timeout < now)	1844	if (timeout < now)
1733	{	1845	{
1734	// timeout occured, take action	1846	// timeout occurred, take action
1735	}	1847	}
1736	else	1848	else
1737	{	1849	{
1738	// callback was invoked, but there was some activity, re-arm	1850	// callback was invoked, but there was some activity, re-arm
1739	// the watcher to fire in last_activity + 60, which is	1851	// the watcher to fire in last_activity + 60, which is
…		…
1766	callback (loop, timer, EV_TIMER);	1878	callback (loop, timer, EV_TIMER);
1767		1879
1768	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
1769	C<last_activity>, no libev calls at all:	1881	C<last_activity>, no libev calls at all:
1770		1882
1771	last_actiivty = ev_now (loop);	1883	last_activity = ev_now (loop);
1772		1884
1773	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
1774	time-out is unlikely to be triggered, much more efficient.	1886	time-out is unlikely to be triggered, much more efficient.
1775		1887
1776	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
…		…
1814		1926
1815	=head3 The special problem of time updates	1927	=head3 The special problem of time updates
1816		1928
1817	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
1818	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
1819	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
1820	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
1821	lots of events in one iteration.	1933	lots of events in one iteration.
1822		1934
1823	The relative timeouts are calculated relative to the C<ev_now ()>	1935	The relative timeouts are calculated relative to the C<ev_now ()>
1824	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
…		…
1941	}	2053	}
1942		2054
1943	ev_timer mytimer;	2055	ev_timer mytimer;
1944	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 */
1945	ev_timer_again (&mytimer); /* start timer */	2057	ev_timer_again (&mytimer); /* start timer */
1946	ev_loop (loop, 0);	2058	ev_run (loop, 0);
1947		2059
1948	// 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":
1949	// reset the timeout to start ticking again at 10 seconds	2061	// reset the timeout to start ticking again at 10 seconds
1950	ev_timer_again (&mytimer);	2062	ev_timer_again (&mytimer);
1951		2063
…		…
1977		2089
1978	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
1979	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
1980	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
1981	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
1982	(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).
1983		2095
1984	=head3 Watcher-Specific Functions and Data Members	2096	=head3 Watcher-Specific Functions and Data Members
1985		2097
1986	=over 4	2098	=over 4
1987		2099
…		…
2115	Example: Call a callback every hour, or, more precisely, whenever the	2227	Example: Call a callback every hour, or, more precisely, whenever the
2116	system time is divisible by 3600. The callback invocation times have	2228	system time is divisible by 3600. The callback invocation times have
2117	potentially a lot of jitter, but good long-term stability.	2229	potentially a lot of jitter, but good long-term stability.
2118		2230
2119	static void	2231	static void
2120	clock_cb (struct ev_loop *loop, ev_io *w, int revents)	2232	clock_cb (struct ev_loop *loop, ev_periodic *w, int revents)
2121	{	2233	{
2122	... 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)
2123	}	2235	}
2124		2236
2125	ev_periodic hourly_tick;	2237	ev_periodic hourly_tick;
…		…
2148		2260
2149	=head2 C<ev_signal> - signal me when a signal gets signalled!	2261	=head2 C<ev_signal> - signal me when a signal gets signalled!
2150		2262
2151	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
2152	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
2153	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
2154	normal event processing, like any other event.	2266	normal event processing, like any other event.
2155		2267
2156	If you want signals to be delivered truly asynchronously, just use	2268	If you want signals to be delivered truly asynchronously, just use
2157	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
2158	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
…		…
2225	Example: Try to exit cleanly on SIGINT.	2337	Example: Try to exit cleanly on SIGINT.
2226		2338
2227	static void	2339	static void
2228	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)	2340	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)
2229	{	2341	{
2230	ev_unloop (loop, EVUNLOOP_ALL);	2342	ev_break (loop, EVBREAK_ALL);
2231	}	2343	}
2232		2344
2233	ev_signal signal_watcher;	2345	ev_signal signal_watcher;
2234	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	2346	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
2235	ev_signal_start (loop, &signal_watcher);	2347	ev_signal_start (loop, &signal_watcher);
…		…
2621		2733
2622	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:
2623	prepare watchers get invoked before the process blocks and check watchers	2735	prepare watchers get invoked before the process blocks and check watchers
2624	afterwards.	2736	afterwards.
2625		2737
2626	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
2627	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>
2628	watchers. Other loops than the current one are fine, however. The	2740	watchers. Other loops than the current one are fine, however. The
2629	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
2630	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,
2631	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
…		…
2799		2911
2800	if (timeout >= 0)	2912	if (timeout >= 0)
2801	// create/start timer	2913	// create/start timer
2802		2914
2803	// poll	2915	// poll
2804	ev_loop (EV_A_ 0);	2916	ev_run (EV_A_ 0);
2805		2917
2806	// stop timer again	2918	// stop timer again
2807	if (timeout >= 0)	2919	if (timeout >= 0)
2808	ev_timer_stop (EV_A_ &to);	2920	ev_timer_stop (EV_A_ &to);
2809		2921
…		…
2887	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).
2888		3000
2889	=item ev_embed_sweep (loop, ev_embed *)	3001	=item ev_embed_sweep (loop, ev_embed *)
2890		3002
2891	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
2892	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
2893	appropriate way for embedded loops.	3005	appropriate way for embedded loops.
2894		3006
2895	=item struct ev_loop *other [read-only]	3007	=item struct ev_loop *other [read-only]
2896		3008
2897	The embedded event loop.	3009	The embedded event loop.
…		…
2957	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
2958	handlers will be invoked, too, of course.	3070	handlers will be invoked, too, of course.
2959		3071
2960	=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?
2961		3073
2962	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
2963	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
2964	sequence should be handled by libev without any problems.	3076	sequence should be handled by libev without any problems.
2965		3077
2966	This changes when the application actually wants to do event handling	3078	This changes when the application actually wants to do event handling
2967	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
…		…
2983	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
2984	signal watchers).	3096	signal watchers).
2985		3097
2986	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
2987	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
2988	C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying	3100	C<ev_loop_destroy (EV_DEFAULT)> followed by C<ev_default_loop (...)>.
2989	the default loop will "orphan" (not stop) all registered watchers, so you	3101	Destroying the default loop will "orphan" (not stop) all registered
2990	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
2991	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.
2992		3105
2993	=head3 Watcher-Specific Functions and Data Members	3106	=head3 Watcher-Specific Functions and Data Members
2994		3107
2995	=over 4	3108	=over 4
2996		3109
2997	=item ev_fork_init (ev_signal *, callback)	3110	=item ev_fork_init (ev_fork *, callback)
2998		3111
2999	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
3000	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,
3001	believe me.	3114	really.
3002		3115
3003	=back	3116	=back
3004		3117
3005		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
3006	=head2 C<ev_async> - how to wake up another event loop	3159	=head2 C<ev_async> - how to wake up an event loop
3007		3160
3008	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
3009	asynchronous sources such as signal handlers (as opposed to multiple event	3162	asynchronous sources such as signal handlers (as opposed to multiple event
3010	loops - those are of course safe to use in different threads).	3163	loops - those are of course safe to use in different threads).
3011		3164
3012	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,
3013	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>
3014	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
3015	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.
3016	safe.
3017		3169
3018	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,
3019	too, are asynchronous in nature, and signals, too, will be compressed	3171	too, are asynchronous in nature, and signals, too, will be compressed
3020	(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
3021	C<ev_async_sent> calls).	3173	C<ev_async_sent> calls).
…		…
3229	=item * Priorities are not currently supported. Initialising priorities	3381	=item * Priorities are not currently supported. Initialising priorities
3230	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
3231	is an ev_pri field.	3383	is an ev_pri field.
3232		3384
3233	=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
3234	first base created (== the default loop) gets the signals.	3386	base that registered the signal gets the signals.
3235		3387
3236	=item * Other members are not supported.	3388	=item * Other members are not supported.
3237		3389
3238	=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
3239	to use the libev header file and library.	3391	to use the libev header file and library.
…		…
3333	myclass obj;	3485	myclass obj;
3334	ev::io iow;	3486	ev::io iow;
3335	iow.set <myclass, &myclass::io_cb> (&obj);	3487	iow.set <myclass, &myclass::io_cb> (&obj);
3336		3488
3337	=item w->set (object *)	3489	=item w->set (object *)
3338
3339	This is an B<experimental> feature that might go away in a future version.
3340		3490
3341	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
3342	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
3343	functor objects without having to manually specify the C<operator ()> all	3493	functor objects without having to manually specify the C<operator ()> all
3344	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
…		…
3384	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
3385	do this when the watcher is inactive (and not pending either).	3535	do this when the watcher is inactive (and not pending either).
3386		3536
3387	=item w->set ([arguments])	3537	=item w->set ([arguments])
3388		3538
3389	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
3390	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
3391	automatically stopped and restarted when reconfiguring it with this	3541	C counterpart, an active watcher gets automatically stopped and restarted
3392	method.	3542	when reconfiguring it with this method.
3393		3543
3394	=item w->start ()	3544	=item w->start ()
3395		3545
3396	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
3397	constructor already stores the event loop.	3547	constructor already stores the event loop.
3398		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
3399	=item w->stop ()	3555	=item w->stop ()
3400		3556
3401	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.
3402		3558
3403	=item w->again () (C<ev::timer>, C<ev::periodic> only)	3559	=item w->again () (C<ev::timer>, C<ev::periodic> only)
…		…
3415		3571
3416	=back	3572	=back
3417		3573
3418	=back	3574	=back
3419		3575
3420	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
3421	the constructor.	3577	watchers in the constructor.
3422		3578
3423	class myclass	3579	class myclass
3424	{	3580	{
3425	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);
3426	ev::idle idle; void idle_cb (ev::idle &w, int revents);	3583	ev::idle idle; void idle_cb (ev::idle &w, int revents);
3427		3584
3428	myclass (int fd)	3585	myclass (int fd)
3429	{	3586	{
3430	io .set <myclass, &myclass::io_cb > (this);	3587	io .set <myclass, &myclass::io_cb > (this);
		3588	io2 .set <myclass, &myclass::io2_cb > (this);
3431	idle.set <myclass, &myclass::idle_cb> (this);	3589	idle.set <myclass, &myclass::idle_cb> (this);
3432		3590
3433	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
3434	}	3595	}
3435	};	3596	};
3436		3597
3437		3598
3438	=head1 OTHER LANGUAGE BINDINGS	3599	=head1 OTHER LANGUAGE BINDINGS
…		…
3512	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,
3513	C<EV_A_> is used when other arguments are following. Example:	3674	C<EV_A_> is used when other arguments are following. Example:
3514		3675
3515	ev_unref (EV_A);	3676	ev_unref (EV_A);
3516	ev_timer_add (EV_A_ watcher);	3677	ev_timer_add (EV_A_ watcher);
3517	ev_loop (EV_A_ 0);	3678	ev_run (EV_A_ 0);
3518		3679
3519	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,
3520	which is often provided by the following macro.	3681	which is often provided by the following macro.
3521		3682
3522	=item C<EV_P>, C<EV_P_>	3683	=item C<EV_P>, C<EV_P_>
…		…
3562	}	3723	}
3563		3724
3564	ev_check check;	3725	ev_check check;
3565	ev_check_init (&check, check_cb);	3726	ev_check_init (&check, check_cb);
3566	ev_check_start (EV_DEFAULT_ &check);	3727	ev_check_start (EV_DEFAULT_ &check);
3567	ev_loop (EV_DEFAULT_ 0);	3728	ev_run (EV_DEFAULT_ 0);
3568		3729
3569	=head1 EMBEDDING	3730	=head1 EMBEDDING
3570		3731
3571	Libev can (and often is) directly embedded into host	3732	Libev can (and often is) directly embedded into host
3572	applications. Examples of applications that embed it include the Deliantra	3733	applications. Examples of applications that embed it include the Deliantra
…		…
3657	define before including (or compiling) any of its files. The default in	3818	define before including (or compiling) any of its files. The default in
3658	the absence of autoconf is documented for every option.	3819	the absence of autoconf is documented for every option.
3659		3820
3660	Symbols marked with "(h)" do not change the ABI, and can have different	3821	Symbols marked with "(h)" do not change the ABI, and can have different
3661	values when compiling libev vs. including F<ev.h>, so it is permissible	3822	values when compiling libev vs. including F<ev.h>, so it is permissible
3662	to redefine them before including F<ev.h> without breakign compatibility	3823	to redefine them before including F<ev.h> without breaking compatibility
3663	to a compiled library. All other symbols change the ABI, which means all	3824	to a compiled library. All other symbols change the ABI, which means all
3664	users of libev and the libev code itself must be compiled with compatible	3825	users of libev and the libev code itself must be compiled with compatible
3665	settings.	3826	settings.
3666		3827
3667	=over 4	3828	=over 4
		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.
3668		3845
3669	=item EV_STANDALONE (h)	3846	=item EV_STANDALONE (h)
3670		3847
3671	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
3672	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
…		…
3879	EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE,	4056	EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE,
3880	EV_ASYNC_ENABLE, EV_CHILD_ENABLE.	4057	EV_ASYNC_ENABLE, EV_CHILD_ENABLE.
3881		4058
3882	If undefined or defined to be C<1> (and the platform supports it), then	4059	If undefined or defined to be C<1> (and the platform supports it), then
3883	the respective watcher type is supported. If defined to be C<0>, then it	4060	the respective watcher type is supported. If defined to be C<0>, then it
3884	is not. Disabling watcher types mainly saves codesize.	4061	is not. Disabling watcher types mainly saves code size.
3885		4062
3886	=item EV_FEATURES	4063	=item EV_FEATURES
3887		4064
3888	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
3889	speed (but with the full API), you can define this symbol to request	4066	speed (but with the full API), you can define this symbol to request
…		…
3909		4086
3910	=item C<1> - faster/larger code	4087	=item C<1> - faster/larger code
3911		4088
3912	Use larger code to speed up some operations.	4089	Use larger code to speed up some operations.
3913		4090
3914	Currently this is used to override some inlining decisions (enlarging the roughly	4091	Currently this is used to override some inlining decisions (enlarging the
3915	30% code size on amd64.	4092	code size by roughly 30% on amd64).
3916		4093
3917	When optimising for size, use of compiler flags such as C<-Os> with	4094	When optimising for size, use of compiler flags such as C<-Os> with
3918	gcc recommended, as well as C<-DNDEBUG>, as libev contains a number of	4095	gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of
3919	assertions.	4096	assertions.
3920		4097
3921	=item C<2> - faster/larger data structures	4098	=item C<2> - faster/larger data structures
3922		4099
3923	Replaces the small 2-heap for timer management by a faster 4-heap, larger	4100	Replaces the small 2-heap for timer management by a faster 4-heap, larger
3924	hash table sizes and so on. This will usually further increase codesize	4101	hash table sizes and so on. This will usually further increase code size
3925	and can additionally have an effect on the size of data structures at	4102	and can additionally have an effect on the size of data structures at
3926	runtime.	4103	runtime.
3927		4104
3928	=item C<4> - full API configuration	4105	=item C<4> - full API configuration
3929		4106
…		…
3966	I/O watcher then might come out at only 5Kb.	4143	I/O watcher then might come out at only 5Kb.
3967		4144
3968	=item EV_AVOID_STDIO	4145	=item EV_AVOID_STDIO
3969		4146
3970	If this is set to C<1> at compiletime, then libev will avoid using stdio	4147	If this is set to C<1> at compiletime, then libev will avoid using stdio
3971	functions (printf, scanf, perror etc.). This will increase the codesize	4148	functions (printf, scanf, perror etc.). This will increase the code size
3972	somewhat, but if your program doesn't otherwise depend on stdio and your	4149	somewhat, but if your program doesn't otherwise depend on stdio and your
3973	libc allows it, this avoids linking in the stdio library which is quite	4150	libc allows it, this avoids linking in the stdio library which is quite
3974	big.	4151	big.
3975		4152
3976	Note that error messages might become less precise when this option is	4153	Note that error messages might become less precise when this option is
…		…
3980		4157
3981	The highest supported signal number, +1 (or, the number of	4158	The highest supported signal number, +1 (or, the number of
3982	signals): Normally, libev tries to deduce the maximum number of signals	4159	signals): Normally, libev tries to deduce the maximum number of signals
3983	automatically, but sometimes this fails, in which case it can be	4160	automatically, but sometimes this fails, in which case it can be
3984	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
3985	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
3986	statically allocates some 12-24 bytes per signal number.	4163	statically allocates some 12-24 bytes per signal number.
3987		4164
3988	=item EV_PID_HASHSIZE	4165	=item EV_PID_HASHSIZE
3989		4166
3990	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
…		…
4022	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it	4199	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
4023	will be C<0>.	4200	will be C<0>.
4024		4201
4025	=item EV_VERIFY	4202	=item EV_VERIFY
4026		4203
4027	Controls how much internal verification (see C<ev_loop_verify ()>) will	4204	Controls how much internal verification (see C<ev_verify ()>) will
4028	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
4029	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
4030	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
4031	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
4032	verification code will be called very frequently, which will slow down	4209	verification code will be called very frequently, which will slow down
…		…
4036	will be C<0>.	4213	will be C<0>.
4037		4214
4038	=item EV_COMMON	4215	=item EV_COMMON
4039		4216
4040	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
4041	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
4042	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,
4043	though, and it must be identical each time.	4220	though, and it must be identical each time.
4044		4221
4045	For example, the perl EV module uses something like this:	4222	For example, the perl EV module uses something like this:
4046		4223
…		…
4247	userdata *u = ev_userdata (EV_A);	4424	userdata *u = ev_userdata (EV_A);
4248	pthread_mutex_lock (&u->lock);	4425	pthread_mutex_lock (&u->lock);
4249	}	4426	}
4250		4427
4251	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
4252	into C<ev_loop>:	4429	into C<ev_run>:
4253		4430
4254	void *	4431	void *
4255	l_run (void *thr_arg)	4432	l_run (void *thr_arg)
4256	{	4433	{
4257	struct ev_loop *loop = (struct ev_loop *)thr_arg;	4434	struct ev_loop *loop = (struct ev_loop *)thr_arg;
4258		4435
4259	l_acquire (EV_A);	4436	l_acquire (EV_A);
4260	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);	4437	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
4261	ev_loop (EV_A_ 0);	4438	ev_run (EV_A_ 0);
4262	l_release (EV_A);	4439	l_release (EV_A);
4263		4440
4264	return 0;	4441	return 0;
4265	}	4442	}
4266		4443
…		…
4318		4495
4319	=head3 COROUTINES	4496	=head3 COROUTINES
4320		4497
4321	Libev is very accommodating to coroutines ("cooperative threads"):	4498	Libev is very accommodating to coroutines ("cooperative threads"):
4322	libev fully supports nesting calls to its functions from different	4499	libev fully supports nesting calls to its functions from different
4323	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
4324	different coroutines, and switch freely between both coroutines running	4501	different coroutines, and switch freely between both coroutines running
4325	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
4326	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.
4327		4504
4328	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
4329	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
4330	they do not call any callbacks.	4507	they do not call any callbacks.
4331		4508
4332	=head2 COMPILER WARNINGS	4509	=head2 COMPILER WARNINGS
4333		4510
4334	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
…		…
4345	maintainable.	4522	maintainable.
4346		4523
4347	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
4348	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
4349	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
4350	warnings that resulted an extreme number of false positives. These have	4527	warnings that resulted in an extreme number of false positives. These have
4351	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
4352	such buggy versions.	4529	such buggy versions.
4353		4530
4354	While libev is written to generate as few warnings as possible,	4531	While libev is written to generate as few warnings as possible,
4355	"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
…		…
4391	I suggest using suppression lists.	4568	I suggest using suppression lists.
4392		4569
4393		4570
4394	=head1 PORTABILITY NOTES	4571	=head1 PORTABILITY NOTES
4395		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
4396	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS	4659	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
		4660
		4661	=head3 General issues
4397		4662
4398	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
4399	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
4400	model. Libev still offers limited functionality on this platform in	4665	model. Libev still offers limited functionality on this platform in
4401	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
4402	descriptors. This only applies when using Win32 natively, not when using	4667	descriptors. This only applies when using Win32 natively, not when using
4403	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.
4404		4671
4405	Lifting these limitations would basically require the full	4672	Lifting these limitations would basically require the full
4406	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,
4407	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
4408	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).
4409		4676
4410	There is no supported compilation method available on windows except	4677	There is no supported compilation method available on windows except
4411	embedding it into other applications.	4678	embedding it into other applications.
4412		4679
4413	Sensible signal handling is officially unsupported by Microsoft - libev	4680	Sensible signal handling is officially unsupported by Microsoft - libev
…		…
4441	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!):
4442		4709
4443	#include "evwrap.h"	4710	#include "evwrap.h"
4444	#include "ev.c"	4711	#include "ev.c"
4445		4712
4446	=over 4
4447
4448	=item The winsocket select function	4713	=head3 The winsocket C<select> function
4449		4714
4450	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
4451	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
4452	also extremely buggy). This makes select very inefficient, and also	4717	also extremely buggy). This makes select very inefficient, and also
4453	requires a mapping from file descriptors to socket handles (the Microsoft	4718	requires a mapping from file descriptors to socket handles (the Microsoft
…		…
4462	#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 */
4463		4728
4464	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
4465	complexity in the O(n²) range when using win32.	4730	complexity in the O(n²) range when using win32.
4466		4731
4467	=item Limited number of file descriptors	4732	=head3 Limited number of file descriptors
4468		4733
4469	Windows has numerous arbitrary (and low) limits on things.	4734	Windows has numerous arbitrary (and low) limits on things.
4470		4735
4471	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
4472	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
…		…
4487	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
4488	(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,
4489	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
4490	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.
4491		4756
4492	=back
4493
4494	=head2 PORTABILITY REQUIREMENTS	4757	=head2 PORTABILITY REQUIREMENTS
4495		4758
4496	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
4497	backend-specific APIs, libev relies on a few additional extensions:	4760	backend-specific APIs, libev relies on a few additional extensions:
4498		4761
…		…
4504	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
4505	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
4506	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
4507	callback: The watcher callbacks have different type signatures, but libev	4770	callback: The watcher callbacks have different type signatures, but libev
4508	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.
4509		4777
4510	=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
4511		4779
4512	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
4513	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
…		…
4536	watchers.	4804	watchers.
4537		4805
4538	=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
4539		4807
4540	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
4541	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
4542	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
4543	implementations implementing IEEE 754, which is basically all existing	4812	implementations using IEEE 754, which is basically all existing ones. With
4544	ones. With IEEE 754 doubles, you get microsecond accuracy until at least	4813	IEEE 754 doubles, you get microsecond accuracy until at least 2200.
4545	2200.
4546		4814
4547	=back	4815	=back
4548		4816
4549	If you know of other additional requirements drop me a note.	4817	If you know of other additional requirements drop me a note.
4550		4818
…		…
4618	involves iterating over all running async watchers or all signal numbers.	4886	involves iterating over all running async watchers or all signal numbers.
4619		4887
4620	=back	4888	=back
4621		4889
4622		4890
4623	=head1 PORTING FROM 3.X TO 4.X	4891	=head1 PORTING FROM LIBEV 3.X TO 4.X
4624		4892
4625	The major version 4 introduced some minor incompatible changes to the API.	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.
4626		4899
4627	=over 4	4900	=over 4
4628		4901
4629	=item C<EV_TIMEOUT> replaced by C<EV_TIMER> in C<revents>	4902	=item C<EV_COMPAT3> backwards compatibility mechanism
4630		4903
4631	This is a simple rename - all other watcher types use their name	4904	The backward compatibility mechanism can be controlled by
4632	as revents flag, and now C<ev_timer> does, too.	4905	C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING>
		4906	section.
4633		4907
4634	Both C<EV_TIMER> and C<EV_TIMEOUT> symbols were present in 3.x versions	4908	=item C<ev_default_destroy> and C<ev_default_fork> have been removed
4635	and continue to be present for the forseeable future, so this is mostly a	4909
4636	documentation change.	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.
4637		4941
4638	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>	4942	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>
4639		4943
4640	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different	4944	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different
4641	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile	4945	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile
…		…
4648		4952
4649	=over 4	4953	=over 4
4650		4954
4651	=item active	4955	=item active
4652		4956
4653	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.
4654	an event loop) but not yet stopped (disassociated from the event loop).	4958	See L<WATCHER STATES> for details.
4655		4959
4656	=item application	4960	=item application
4657		4961
4658	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.
4659		4967
4660	=item callback	4968	=item callback
4661		4969
4662	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
4663	detected. Callbacks are being passed the event loop, the watcher that	4971	detected. Callbacks are being passed the event loop, the watcher that
4664	received the event, and the actual event bitset.	4972	received the event, and the actual event bitset.
4665		4973
4666	=item callback invocation	4974	=item callback/watcher invocation
4667		4975
4668	The act of calling the callback associated with a watcher.	4976	The act of calling the callback associated with a watcher.
4669		4977
4670	=item event	4978	=item event
4671		4979
…		…
4690	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
4691	watchers and events.	4999	watchers and events.
4692		5000
4693	=item pending	5001	=item pending
4694		5002
4695	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
4696	and stops being pending as soon as the watcher will be invoked or its	5004	detected. See L<WATCHER STATES> for details.
4697	pending status is explicitly cleared by the application.
4698
4699	A watcher can be pending, but not active. Stopping a watcher also clears
4700	its pending status.
4701		5005
4702	=item real time	5006	=item real time
4703		5007
4704	The physical time that is observed. It is apparently strictly monotonic :)	5008	The physical time that is observed. It is apparently strictly monotonic :)
4705		5009
…		…
4712	=item watcher	5016	=item watcher
4713		5017
4714	A data structure that describes interest in certain events. Watchers need	5018	A data structure that describes interest in certain events. Watchers need
4715	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.
4716		5020
4717	=item watcher invocation
4718
4719	The act of calling the callback associated with a watcher.
4720
4721	=back	5021	=back
4722		5022
4723	=head1 AUTHOR	5023	=head1 AUTHOR
4724		5024
4725	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.
4726		5027

Diff Legend

–	Removed lines
+	Added lines
<	Changed lines
>	Changed lines