ViewVC Help

View File | Revision Log | Show Annotations | Download File

/cvs/libev/ev.pod

Comparing libev/ev.pod (file contents):
Revision 1.286 by root, Tue Mar 16 00:26:41 2010 UTC vs.
Revision 1.339 by root, Sun Oct 31 22:19:38 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
…		…
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. Unlike the default loop, it cannot
573	handle signal and child watchers, and attempts to do so will be greeted by
574	undefined behaviour (or a failed assertion if assertions are enabled).
575
576	Note that this function I<is> thread-safe, and the recommended way to use
577	libev with threads is indeed to create one loop per thread, and using the
578	default loop in the "main" or "initial" thread.
579
580	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.
581		595
582	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	596	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
583	if (!epoller)	597	if (!epoller)
584	fatal ("no epoll found here, maybe it hides under your chair");	598	fatal ("no epoll found here, maybe it hides under your chair");
585		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
586	=item ev_default_destroy ()	605	=item ev_loop_destroy (loop)
587		606
588	Destroys the default loop again (frees all memory and kernel state	607	Destroys an event loop object (frees all memory and kernel state
589	etc.). None of the active event watchers will be stopped in the normal	608	etc.). None of the active event watchers will be stopped in the normal
590	sense, so e.g. C<ev_is_active> might still return true. It is your	609	sense, so e.g. C<ev_is_active> might still return true. It is your
591	responsibility to either stop all watchers cleanly yourself I<before>	610	responsibility to either stop all watchers cleanly yourself I<before>
592	calling this function, or cope with the fact afterwards (which is usually	611	calling this function, or cope with the fact afterwards (which is usually
593	the easiest thing, you can just ignore the watchers and/or C<free ()> them	612	the easiest thing, you can just ignore the watchers and/or C<free ()> them
…		…
595		614
596	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
597	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
598	as signal and child watchers) would need to be stopped manually.	617	as signal and child watchers) would need to be stopped manually.
599		618
600	In general it is not advisable to call this function except in the	619	This function is normally used on loop objects allocated by
601	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 it's resources.
602	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>
603	C<ev_loop_new> and C<ev_loop_destroy>.	626	and C<ev_loop_destroy>.
604		627
605	=item ev_loop_destroy (loop)	628	=item ev_loop_fork (loop)
606		629
607	Like C<ev_default_destroy>, but destroys an event loop created by an
608	earlier call to C<ev_loop_new>.
609
610	=item ev_default_fork ()
611
612	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
613	to reinitialise the kernel state for backends that have one. Despite the	631	reinitialise the kernel state for backends that have one. Despite the
614	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
615	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
616	sense). You I<must> call it in the child before using any of the libev	634	child before resuming or calling C<ev_run>.
617	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.
618		640
619	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
620	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
621	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).
622		647
623	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
624	it just in case after a fork. To make this easy, the function will fit in	649	it just in case after a fork.
625	quite nicely into a call to C<pthread_atfork>:
626		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	...
627	pthread_atfork (0, 0, ev_default_fork);	661	pthread_atfork (0, 0, post_fork_child);
628
629	=item ev_loop_fork (loop)
630
631	Like C<ev_default_fork>, but acts on an event loop created by
632	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
633	after fork that you want to re-use in the child, and how you do this is
634	entirely your own problem.
635		662
636	=item int ev_is_default_loop (loop)	663	=item int ev_is_default_loop (loop)
637		664
638	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
639	otherwise.	666	otherwise.
640		667
641	=item unsigned int ev_loop_count (loop)	668	=item unsigned int ev_iteration (loop)
642		669
643	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
644	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>
645	happily wraps around with enough iterations.	672	and happily wraps around with enough iterations.
646		673
647	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
648	"ticks" the number of loop iterations), as it roughly corresponds with	675	"ticks" the number of loop iterations), as it roughly corresponds with
649	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.
650		678
651	=item unsigned int ev_loop_depth (loop)	679	=item unsigned int ev_depth (loop)
652		680
653	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
654	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.
655		683
656	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
657	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),
658	in which case it is higher.	686	in which case it is higher.
659		687
660	Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread	688	Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread
661	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.
662		691
663	=item unsigned int ev_backend (loop)	692	=item unsigned int ev_backend (loop)
664		693
665	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
666	use.	695	use.
…		…
675		704
676	=item ev_now_update (loop)	705	=item ev_now_update (loop)
677		706
678	Establishes the current time by querying the kernel, updating the time	707	Establishes the current time by querying the kernel, updating the time
679	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
680	is usually done automatically within C<ev_loop ()>.	709	is usually done automatically within C<ev_run ()>.
681		710
682	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
683	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
684	the current time is a good idea.	713	the current time is a good idea.
685		714
…		…
687		716
688	=item ev_suspend (loop)	717	=item ev_suspend (loop)
689		718
690	=item ev_resume (loop)	719	=item ev_resume (loop)
691		720
692	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
693	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.
694		723
695	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
696	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
697	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
698	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>
…		…
700	C<ev_resume> directly afterwards to resume timer processing.	729	C<ev_resume> directly afterwards to resume timer processing.
701		730
702	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
703	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
704	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
705	occured while suspended).	734	occurred while suspended).
706		735
707	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
708	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>
709	without a previous call to C<ev_suspend>.	738	without a previous call to C<ev_suspend>.
710		739
711	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
712	event loop time (see C<ev_now_update>).	741	event loop time (see C<ev_now_update>).
713		742
714	=item ev_loop (loop, int flags)	743	=item ev_run (loop, int flags)
715		744
716	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
717	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
718	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>.
719		750
720	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
721	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.
722		754
723	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
724	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
725	finished (especially in interactive programs), but having a program	757	finished (especially in interactive programs), but having a program
726	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
727	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
728	beauty.	760	beauty.
729		761
730	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
731	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
732	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
733	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.
734		767
735	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
736	necessary) and will handle those and any already outstanding ones. It	769	necessary) and will handle those and any already outstanding ones. It
737	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
738	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
739	user-registered callback will be called), and will return after one	772	user-registered callback will be called), and will return after one
740	iteration of the loop.	773	iteration of the loop.
741		774
742	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
743	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
744	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
745	usually a better approach for this kind of thing.	778	usually a better approach for this kind of thing.
746		779
747	Here are the gory details of what C<ev_loop> does:	780	Here are the gory details of what C<ev_run> does:
748		781
		782	- Increment loop depth.
		783	- Reset the ev_break status.
749	- Before the first iteration, call any pending watchers.	784	- Before the first iteration, call any pending watchers.
		785	LOOP:
750	* If EVFLAG_FORKCHECK was used, check for a fork.	786	- If EVFLAG_FORKCHECK was used, check for a fork.
751	- 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.
752	- Queue and call all prepare watchers.	788	- Queue and call all prepare watchers.
		789	- If ev_break was called, goto FINISH.
753	- If we have been forked, detach and recreate the kernel state	790	- If we have been forked, detach and recreate the kernel state
754	as to not disturb the other process.	791	as to not disturb the other process.
755	- Update the kernel state with all outstanding changes.	792	- Update the kernel state with all outstanding changes.
756	- Update the "event loop time" (ev_now ()).	793	- Update the "event loop time" (ev_now ()).
757	- Calculate for how long to sleep or block, if at all	794	- Calculate for how long to sleep or block, if at all
758	(active idle watchers, EVLOOP_NONBLOCK or not having	795	(active idle watchers, EVRUN_NOWAIT or not having
759	any active watchers at all will result in not sleeping).	796	any active watchers at all will result in not sleeping).
760	- 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.
761	- Block the process, waiting for any events.	799	- Block the process, waiting for any events.
762	- Queue all outstanding I/O (fd) events.	800	- Queue all outstanding I/O (fd) events.
763	- 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.
764	- Queue all expired timers.	802	- Queue all expired timers.
765	- Queue all expired periodics.	803	- Queue all expired periodics.
766	- Unless any events are pending now, queue all idle watchers.	804	- Queue all idle watchers with priority higher than that of pending events.
767	- Queue all check watchers.	805	- Queue all check watchers.
768	- 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).
769	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
770	be handled here by queueing them when their watcher gets executed.	808	be handled here by queueing them when their watcher gets executed.
771	- 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
772	were used, or there are no active watchers, return, otherwise	810	were used, or there are no active watchers, goto FINISH, otherwise
773	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.
774		816
775	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
776	anymore.	818	anymore.
777		819
778	... queue jobs here, make sure they register event watchers as long	820	... queue jobs here, make sure they register event watchers as long
779	... 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..)
780	ev_loop (my_loop, 0);	822	ev_run (my_loop, 0);
781	... jobs done or somebody called unloop. yeah!	823	... jobs done or somebody called unloop. yeah!
782		824
783	=item ev_unloop (loop, how)	825	=item ev_break (loop, how)
784		826
785	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
786	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
787	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
788	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.
789		831
790	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.
791		833
792	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.
793		835
794	=item ev_ref (loop)	836	=item ev_ref (loop)
795		837
796	=item ev_unref (loop)	838	=item ev_unref (loop)
797		839
798	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
799	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
800	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.
801		843
802	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
803	unregister, but that nevertheless should not keep C<ev_loop> from	845	unregister, but that nevertheless should not keep C<ev_run> from
804	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>
805	before stopping it.	847	before stopping it.
806		848
807	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
808	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
809	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
810	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
811	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
812	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
813	before, respectively. Note also that libev might stop watchers itself	855	before, respectively. Note also that libev might stop watchers itself
814	(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>
815	in the callback).	857	in the callback).
816		858
817	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>
818	running when nothing else is active.	860	running when nothing else is active.
819		861
820	ev_signal exitsig;	862	ev_signal exitsig;
821	ev_signal_init (&exitsig, sig_cb, SIGINT);	863	ev_signal_init (&exitsig, sig_cb, SIGINT);
822	ev_signal_start (loop, &exitsig);	864	ev_signal_start (loop, &exitsig);
…		…
867	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>,
868	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
869	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
870	parallelity, then this setting will limit your transaction rate (if you	912	parallelity, then this setting will limit your transaction rate (if you
871	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,
872	then you can't do more than 100 transations per second).	914	then you can't do more than 100 transactions per second).
873		915
874	Setting the I<timeout collect interval> can improve the opportunity for	916	Setting the I<timeout collect interval> can improve the opportunity for
875	saving power, as the program will "bundle" timer callback invocations that	917	saving power, as the program will "bundle" timer callback invocations that
876	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
877	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
…		…
885	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);	927	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);
886		928
887	=item ev_invoke_pending (loop)	929	=item ev_invoke_pending (loop)
888		930
889	This call will simply invoke all pending watchers while resetting their	931	This call will simply invoke all pending watchers while resetting their
890	pending state. Normally, C<ev_loop> does this automatically when required,	932	pending state. Normally, C<ev_run> does this automatically when required,
891	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).
892		938
893	=item int ev_pending_count (loop)	939	=item int ev_pending_count (loop)
894		940
895	Returns the number of pending watchers - zero indicates that no watchers	941	Returns the number of pending watchers - zero indicates that no watchers
896	are pending.	942	are pending.
897		943
898	=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))
899		945
900	This overrides the invoke pending functionality of the loop: Instead of	946	This overrides the invoke pending functionality of the loop: Instead of
901	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
902	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
903	invoke the actual watchers inside another context (another thread etc.).	949	invoke the actual watchers inside another context (another thread etc.).
904		950
905	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
906	callback.	952	callback.
…		…
909		955
910	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
911	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
912	each call to a libev function.	958	each call to a libev function.
913		959
914	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
915	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
916	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
917	and I<acquire> callbacks on the loop.	963	I<release> and I<acquire> callbacks on the loop.
918		964
919	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
920	suspended waiting for new events, and C<acquire> is called just	966	suspended waiting for new events, and C<acquire> is called just
921	afterwards.	967	afterwards.
922		968
…		…
925		971
926	While event loop modifications are allowed between invocations of	972	While event loop modifications are allowed between invocations of
927	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
928	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
929	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
930	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
931	to take note of any changes you made.	977	to take note of any changes you made.
932		978
933	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
934	invocations of C<release> and C<acquire>.	980	invocations of C<release> and C<acquire>.
935		981
936	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
937	document.	983	document.
938		984
…		…
947	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,
948	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
949	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
950	any other purpose as well.	996	any other purpose as well.
951		997
952	=item ev_loop_verify (loop)	998	=item ev_verify (loop)
953		999
954	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
955	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
956	through all internal structures and checks them for validity. If anything	1002	through all internal structures and checks them for validity. If anything
957	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
…		…
968		1014
969	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
970	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
971	watchers and C<ev_io_start> for I/O watchers.	1017	watchers and C<ev_io_start> for I/O watchers.
972		1018
973	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
974	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
975	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:
976		1023
977	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)
978	{	1025	{
979	ev_io_stop (w);	1026	ev_io_stop (w);
980	ev_unloop (loop, EVUNLOOP_ALL);	1027	ev_break (loop, EVBREAK_ALL);
981	}	1028	}
982		1029
983	struct ev_loop *loop = ev_default_loop (0);	1030	struct ev_loop *loop = ev_default_loop (0);
984		1031
985	ev_io stdin_watcher;	1032	ev_io stdin_watcher;
986		1033
987	ev_init (&stdin_watcher, my_cb);	1034	ev_init (&stdin_watcher, my_cb);
988	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	1035	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
989	ev_io_start (loop, &stdin_watcher);	1036	ev_io_start (loop, &stdin_watcher);
990		1037
991	ev_loop (loop, 0);	1038	ev_run (loop, 0);
992		1039
993	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
994	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
995	stack).	1042	stack).
996		1043
997	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>
998	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).
999		1046
1000	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
1001	(watcher *, callback)>, which expects a callback to be provided. This	1048	*, callback)>, which expects a callback to be provided. This callback is
1002	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
1003	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
1004	is readable and/or writable).	1051	and/or writable).
1005		1052
1006	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 *, ...) >>
1007	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
1008	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<<
1009	ev_TYPE_init (watcher *, callback, ...) >>.	1056	ev_TYPE_init (watcher *, callback, ...) >>.
…		…
1032	=item C<EV_WRITE>	1079	=item C<EV_WRITE>
1033		1080
1034	The file descriptor in the C<ev_io> watcher has become readable and/or	1081	The file descriptor in the C<ev_io> watcher has become readable and/or
1035	writable.	1082	writable.
1036		1083
1037	=item C<EV_TIMEOUT>	1084	=item C<EV_TIMER>
1038		1085
1039	The C<ev_timer> watcher has timed out.	1086	The C<ev_timer> watcher has timed out.
1040		1087
1041	=item C<EV_PERIODIC>	1088	=item C<EV_PERIODIC>
1042		1089
…		…
1060		1107
1061	=item C<EV_PREPARE>	1108	=item C<EV_PREPARE>
1062		1109
1063	=item C<EV_CHECK>	1110	=item C<EV_CHECK>
1064		1111
1065	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
1066	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
1067	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
1068	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
1069	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
1070	(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
1071	C<ev_loop> from blocking).	1118	C<ev_run> from blocking).
1072		1119
1073	=item C<EV_EMBED>	1120	=item C<EV_EMBED>
1074		1121
1075	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.
1076		1123
1077	=item C<EV_FORK>	1124	=item C<EV_FORK>
1078		1125
1079	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
1080	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>).
1081		1132
1082	=item C<EV_ASYNC>	1133	=item C<EV_ASYNC>
1083		1134
1084	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>).
1085		1136
…		…
1257		1308
1258	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
1259	functions that do not need a watcher.	1310	functions that do not need a watcher.
1260		1311
1261	=back	1312	=back
1262
1263		1313
1264	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	1314	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
1265		1315
1266	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
1267	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
…		…
1323	t2_cb (EV_P_ ev_timer *w, int revents)	1373	t2_cb (EV_P_ ev_timer *w, int revents)
1324	{	1374	{
1325	struct my_biggy big = (struct my_biggy *)	1375	struct my_biggy big = (struct my_biggy *)
1326	(((char *)w) - offsetof (struct my_biggy, t2));	1376	(((char *)w) - offsetof (struct my_biggy, t2));
1327	}	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
1328		1437
1329	=head2 WATCHER PRIORITY MODELS	1438	=head2 WATCHER PRIORITY MODELS
1330		1439
1331	Many event loops support I<watcher priorities>, which are usually small	1440	Many event loops support I<watcher priorities>, which are usually small
1332	integers that influence the ordering of event callback invocation	1441	integers that influence the ordering of event callback invocation
…		…
1375		1484
1376	For example, to emulate how many other event libraries handle priorities,	1485	For example, to emulate how many other event libraries handle priorities,
1377	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
1378	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
1379	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
1380	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
1381	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
1382	workable.	1491	workable.
1383		1492
1384	Usually, however, the lock-out model implemented that way will perform	1493	Usually, however, the lock-out model implemented that way will perform
1385	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,
…		…
1399	{	1508	{
1400	// stop the I/O watcher, we received the event, but	1509	// stop the I/O watcher, we received the event, but
1401	// are not yet ready to handle it.	1510	// are not yet ready to handle it.
1402	ev_io_stop (EV_A_ w);	1511	ev_io_stop (EV_A_ w);
1403		1512
1404	// start the idle watcher to ahndle the actual event.	1513	// start the idle watcher to handle the actual event.
1405	// it will not be executed as long as other watchers	1514	// it will not be executed as long as other watchers
1406	// with the default priority are receiving events.	1515	// with the default priority are receiving events.
1407	ev_idle_start (EV_A_ &idle);	1516	ev_idle_start (EV_A_ &idle);
1408	}	1517	}
1409		1518
…		…
1463		1572
1464	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
1465	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
1466	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
1467	descriptors for which non-blocking operation makes no sense (such as	1576	descriptors for which non-blocking operation makes no sense (such as
1468	files) - libev doesn't guarentee any specific behaviour in that case.	1577	files) - libev doesn't guarantee any specific behaviour in that case.
1469		1578
1470	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
1471	receive "spurious" readiness notifications, that is your callback might	1580	receive "spurious" readiness notifications, that is your callback might
1472	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
1473	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
…		…
1541	somewhere, as that would have given you a big clue).	1650	somewhere, as that would have given you a big clue).
1542		1651
1543	=head3 The special problem of accept()ing when you can't	1652	=head3 The special problem of accept()ing when you can't
1544		1653
1545	Many implementations of the POSIX C<accept> function (for example,	1654	Many implementations of the POSIX C<accept> function (for example,
1546	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
1547	connection from the pending queue in all error cases.	1656	connection from the pending queue in all error cases.
1548		1657
1549	For example, larger servers often run out of file descriptors (because	1658	For example, larger servers often run out of file descriptors (because
1550	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
1551	rejecting the connection, leading to libev signalling readiness on	1660	rejecting the connection, leading to libev signalling readiness on
…		…
1617	...	1726	...
1618	struct ev_loop *loop = ev_default_init (0);	1727	struct ev_loop *loop = ev_default_init (0);
1619	ev_io stdin_readable;	1728	ev_io stdin_readable;
1620	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);
1621	ev_io_start (loop, &stdin_readable);	1730	ev_io_start (loop, &stdin_readable);
1622	ev_loop (loop, 0);	1731	ev_run (loop, 0);
1623		1732
1624		1733
1625	=head2 C<ev_timer> - relative and optionally repeating timeouts	1734	=head2 C<ev_timer> - relative and optionally repeating timeouts
1626		1735
1627	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
…		…
1636	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
1637	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
1638	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
1639	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
1640	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
1641	no longer true when a callback calls C<ev_loop> recursively).	1750	no longer true when a callback calls C<ev_run> recursively).
1642		1751
1643	=head3 Be smart about timeouts	1752	=head3 Be smart about timeouts
1644		1753
1645	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
1646	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,
…		…
1732	ev_tstamp timeout = last_activity + 60.;	1841	ev_tstamp timeout = last_activity + 60.;
1733		1842
1734	// 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
1735	if (timeout < now)	1844	if (timeout < now)
1736	{	1845	{
1737	// timeout occured, take action	1846	// timeout occurred, take action
1738	}	1847	}
1739	else	1848	else
1740	{	1849	{
1741	// callback was invoked, but there was some activity, re-arm	1850	// callback was invoked, but there was some activity, re-arm
1742	// the watcher to fire in last_activity + 60, which is	1851	// the watcher to fire in last_activity + 60, which is
…		…
1764	to the current time (meaning we just have some activity :), then call the	1873	to the current time (meaning we just have some activity :), then call the
1765	callback, which will "do the right thing" and start the timer:	1874	callback, which will "do the right thing" and start the timer:
1766		1875
1767	ev_init (timer, callback);	1876	ev_init (timer, callback);
1768	last_activity = ev_now (loop);	1877	last_activity = ev_now (loop);
1769	callback (loop, timer, EV_TIMEOUT);	1878	callback (loop, timer, EV_TIMER);
1770		1879
1771	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
1772	C<last_activity>, no libev calls at all:	1881	C<last_activity>, no libev calls at all:
1773		1882
1774	last_actiivty = ev_now (loop);	1883	last_activity = ev_now (loop);
1775		1884
1776	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
1777	time-out is unlikely to be triggered, much more efficient.	1886	time-out is unlikely to be triggered, much more efficient.
1778		1887
1779	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
…		…
1817		1926
1818	=head3 The special problem of time updates	1927	=head3 The special problem of time updates
1819		1928
1820	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
1821	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
1822	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
1823	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
1824	lots of events in one iteration.	1933	lots of events in one iteration.
1825		1934
1826	The relative timeouts are calculated relative to the C<ev_now ()>	1935	The relative timeouts are calculated relative to the C<ev_now ()>
1827	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
…		…
1944	}	2053	}
1945		2054
1946	ev_timer mytimer;	2055	ev_timer mytimer;
1947	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 */
1948	ev_timer_again (&mytimer); /* start timer */	2057	ev_timer_again (&mytimer); /* start timer */
1949	ev_loop (loop, 0);	2058	ev_run (loop, 0);
1950		2059
1951	// 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":
1952	// reset the timeout to start ticking again at 10 seconds	2061	// reset the timeout to start ticking again at 10 seconds
1953	ev_timer_again (&mytimer);	2062	ev_timer_again (&mytimer);
1954		2063
…		…
1980		2089
1981	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
1982	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
1983	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
1984	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
1985	(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).
1986		2095
1987	=head3 Watcher-Specific Functions and Data Members	2096	=head3 Watcher-Specific Functions and Data Members
1988		2097
1989	=over 4	2098	=over 4
1990		2099
…		…
2118	Example: Call a callback every hour, or, more precisely, whenever the	2227	Example: Call a callback every hour, or, more precisely, whenever the
2119	system time is divisible by 3600. The callback invocation times have	2228	system time is divisible by 3600. The callback invocation times have
2120	potentially a lot of jitter, but good long-term stability.	2229	potentially a lot of jitter, but good long-term stability.
2121		2230
2122	static void	2231	static void
2123	clock_cb (struct ev_loop *loop, ev_io *w, int revents)	2232	clock_cb (struct ev_loop *loop, ev_periodic *w, int revents)
2124	{	2233	{
2125	... 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)
2126	}	2235	}
2127		2236
2128	ev_periodic hourly_tick;	2237	ev_periodic hourly_tick;
…		…
2228	Example: Try to exit cleanly on SIGINT.	2337	Example: Try to exit cleanly on SIGINT.
2229		2338
2230	static void	2339	static void
2231	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)	2340	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)
2232	{	2341	{
2233	ev_unloop (loop, EVUNLOOP_ALL);	2342	ev_break (loop, EVBREAK_ALL);
2234	}	2343	}
2235		2344
2236	ev_signal signal_watcher;	2345	ev_signal signal_watcher;
2237	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	2346	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
2238	ev_signal_start (loop, &signal_watcher);	2347	ev_signal_start (loop, &signal_watcher);
…		…
2624		2733
2625	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:
2626	prepare watchers get invoked before the process blocks and check watchers	2735	prepare watchers get invoked before the process blocks and check watchers
2627	afterwards.	2736	afterwards.
2628		2737
2629	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
2630	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>
2631	watchers. Other loops than the current one are fine, however. The	2740	watchers. Other loops than the current one are fine, however. The
2632	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
2633	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,
2634	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
…		…
2802		2911
2803	if (timeout >= 0)	2912	if (timeout >= 0)
2804	// create/start timer	2913	// create/start timer
2805		2914
2806	// poll	2915	// poll
2807	ev_loop (EV_A_ 0);	2916	ev_run (EV_A_ 0);
2808		2917
2809	// stop timer again	2918	// stop timer again
2810	if (timeout >= 0)	2919	if (timeout >= 0)
2811	ev_timer_stop (EV_A_ &to);	2920	ev_timer_stop (EV_A_ &to);
2812		2921
…		…
2890	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).
2891		3000
2892	=item ev_embed_sweep (loop, ev_embed *)	3001	=item ev_embed_sweep (loop, ev_embed *)
2893		3002
2894	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
2895	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
2896	appropriate way for embedded loops.	3005	appropriate way for embedded loops.
2897		3006
2898	=item struct ev_loop *other [read-only]	3007	=item struct ev_loop *other [read-only]
2899		3008
2900	The embedded event loop.	3009	The embedded event loop.
…		…
2960	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
2961	handlers will be invoked, too, of course.	3070	handlers will be invoked, too, of course.
2962		3071
2963	=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?
2964		3073
2965	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
2966	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
2967	sequence should be handled by libev without any problems.	3076	sequence should be handled by libev without any problems.
2968		3077
2969	This changes when the application actually wants to do event handling	3078	This changes when the application actually wants to do event handling
2970	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
…		…
2986	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
2987	signal watchers).	3096	signal watchers).
2988		3097
2989	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
2990	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
2991	C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying	3100	C<ev_loop_destroy (EV_DEFAULT)> followed by C<ev_default_loop (...)>.
2992	the default loop will "orphan" (not stop) all registered watchers, so you	3101	Destroying the default loop will "orphan" (not stop) all registered
2993	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
2994	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.
2995		3105
2996	=head3 Watcher-Specific Functions and Data Members	3106	=head3 Watcher-Specific Functions and Data Members
2997		3107
2998	=over 4	3108	=over 4
2999		3109
3000	=item ev_fork_init (ev_signal *, callback)	3110	=item ev_fork_init (ev_fork *, callback)
3001		3111
3002	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
3003	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,
3004	believe me.	3114	really.
3005		3115
3006	=back	3116	=back
3007		3117
3008		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
3009	=head2 C<ev_async> - how to wake up another event loop	3159	=head2 C<ev_async> - how to wake up an event loop
3010		3160
3011	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
3012	asynchronous sources such as signal handlers (as opposed to multiple event	3162	asynchronous sources such as signal handlers (as opposed to multiple event
3013	loops - those are of course safe to use in different threads).	3163	loops - those are of course safe to use in different threads).
3014		3164
3015	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,
3016	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>
3017	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
3018	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.
3019	safe.
3020		3169
3021	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,
3022	too, are asynchronous in nature, and signals, too, will be compressed	3171	too, are asynchronous in nature, and signals, too, will be compressed
3023	(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
3024	C<ev_async_sent> calls).	3173	C<ev_async_sent> calls).
…		…
3179		3328
3180	If C<timeout> is less than 0, then no timeout watcher will be	3329	If C<timeout> is less than 0, then no timeout watcher will be
3181	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and	3330	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and
3182	repeat = 0) will be started. C<0> is a valid timeout.	3331	repeat = 0) will be started. C<0> is a valid timeout.
3183		3332
3184	The callback has the type C<void (*cb)(int revents, void *arg)> and gets	3333	The callback has the type C<void (*cb)(int revents, void *arg)> and is
3185	passed an C<revents> set like normal event callbacks (a combination of	3334	passed an C<revents> set like normal event callbacks (a combination of
3186	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>	3335	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMER>) and the C<arg>
3187	value passed to C<ev_once>. Note that it is possible to receive I<both>	3336	value passed to C<ev_once>. Note that it is possible to receive I<both>
3188	a timeout and an io event at the same time - you probably should give io	3337	a timeout and an io event at the same time - you probably should give io
3189	events precedence.	3338	events precedence.
3190		3339
3191	Example: wait up to ten seconds for data to appear on STDIN_FILENO.	3340	Example: wait up to ten seconds for data to appear on STDIN_FILENO.
3192		3341
3193	static void stdin_ready (int revents, void *arg)	3342	static void stdin_ready (int revents, void *arg)
3194	{	3343	{
3195	if (revents & EV_READ)	3344	if (revents & EV_READ)
3196	/* stdin might have data for us, joy! */;	3345	/* stdin might have data for us, joy! */;
3197	else if (revents & EV_TIMEOUT)	3346	else if (revents & EV_TIMER)
3198	/* doh, nothing entered */;	3347	/* doh, nothing entered */;
3199	}	3348	}
3200		3349
3201	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	3350	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
3202		3351
…		…
3336	myclass obj;	3485	myclass obj;
3337	ev::io iow;	3486	ev::io iow;
3338	iow.set <myclass, &myclass::io_cb> (&obj);	3487	iow.set <myclass, &myclass::io_cb> (&obj);
3339		3488
3340	=item w->set (object *)	3489	=item w->set (object *)
3341
3342	This is an B<experimental> feature that might go away in a future version.
3343		3490
3344	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
3345	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
3346	functor objects without having to manually specify the C<operator ()> all	3493	functor objects without having to manually specify the C<operator ()> all
3347	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
…		…
3387	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
3388	do this when the watcher is inactive (and not pending either).	3535	do this when the watcher is inactive (and not pending either).
3389		3536
3390	=item w->set ([arguments])	3537	=item w->set ([arguments])
3391		3538
3392	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
3393	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
3394	automatically stopped and restarted when reconfiguring it with this	3541	C counterpart, an active watcher gets automatically stopped and restarted
3395	method.	3542	when reconfiguring it with this method.
3396		3543
3397	=item w->start ()	3544	=item w->start ()
3398		3545
3399	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
3400	constructor already stores the event loop.	3547	constructor already stores the event loop.
3401		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
3402	=item w->stop ()	3555	=item w->stop ()
3403		3556
3404	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.
3405		3558
3406	=item w->again () (C<ev::timer>, C<ev::periodic> only)	3559	=item w->again () (C<ev::timer>, C<ev::periodic> only)
…		…
3418		3571
3419	=back	3572	=back
3420		3573
3421	=back	3574	=back
3422		3575
3423	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
3424	the constructor.	3577	watchers in the constructor.
3425		3578
3426	class myclass	3579	class myclass
3427	{	3580	{
3428	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);
3429	ev::idle idle; void idle_cb (ev::idle &w, int revents);	3583	ev::idle idle; void idle_cb (ev::idle &w, int revents);
3430		3584
3431	myclass (int fd)	3585	myclass (int fd)
3432	{	3586	{
3433	io .set <myclass, &myclass::io_cb > (this);	3587	io .set <myclass, &myclass::io_cb > (this);
		3588	io2 .set <myclass, &myclass::io2_cb > (this);
3434	idle.set <myclass, &myclass::idle_cb> (this);	3589	idle.set <myclass, &myclass::idle_cb> (this);
3435		3590
3436	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
3437	}	3595	}
3438	};	3596	};
3439		3597
3440		3598
3441	=head1 OTHER LANGUAGE BINDINGS	3599	=head1 OTHER LANGUAGE BINDINGS
…		…
3515	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,
3516	C<EV_A_> is used when other arguments are following. Example:	3674	C<EV_A_> is used when other arguments are following. Example:
3517		3675
3518	ev_unref (EV_A);	3676	ev_unref (EV_A);
3519	ev_timer_add (EV_A_ watcher);	3677	ev_timer_add (EV_A_ watcher);
3520	ev_loop (EV_A_ 0);	3678	ev_run (EV_A_ 0);
3521		3679
3522	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,
3523	which is often provided by the following macro.	3681	which is often provided by the following macro.
3524		3682
3525	=item C<EV_P>, C<EV_P_>	3683	=item C<EV_P>, C<EV_P_>
…		…
3565	}	3723	}
3566		3724
3567	ev_check check;	3725	ev_check check;
3568	ev_check_init (&check, check_cb);	3726	ev_check_init (&check, check_cb);
3569	ev_check_start (EV_DEFAULT_ &check);	3727	ev_check_start (EV_DEFAULT_ &check);
3570	ev_loop (EV_DEFAULT_ 0);	3728	ev_run (EV_DEFAULT_ 0);
3571		3729
3572	=head1 EMBEDDING	3730	=head1 EMBEDDING
3573		3731
3574	Libev can (and often is) directly embedded into host	3732	Libev can (and often is) directly embedded into host
3575	applications. Examples of applications that embed it include the Deliantra	3733	applications. Examples of applications that embed it include the Deliantra
…		…
3660	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
3661	the absence of autoconf is documented for every option.	3819	the absence of autoconf is documented for every option.
3662		3820
3663	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
3664	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
3665	to redefine them before including F<ev.h> without breakign compatibility	3823	to redefine them before including F<ev.h> without breaking compatibility
3666	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
3667	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
3668	settings.	3826	settings.
3669		3827
3670	=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.
3671		3845
3672	=item EV_STANDALONE (h)	3846	=item EV_STANDALONE (h)
3673		3847
3674	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
3675	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
…		…
3882	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,
3883	EV_ASYNC_ENABLE, EV_CHILD_ENABLE.	4057	EV_ASYNC_ENABLE, EV_CHILD_ENABLE.
3884		4058
3885	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
3886	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
3887	is not. Disabling watcher types mainly saves codesize.	4061	is not. Disabling watcher types mainly saves code size.
3888		4062
3889	=item EV_FEATURES	4063	=item EV_FEATURES
3890		4064
3891	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
3892	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
3893	certain subsets of functionality. The default is to enable all features	4067	certain subsets of functionality. The default is to enable all features
3894	that can be enabled on the platform.	4068	that can be enabled on the platform.
3895
3896	Note that using autoconf will usually override most of the features, so
3897	using this symbol makes sense mostly when embedding libev.
3898		4069
3899	A typical way to use this symbol is to define it to C<0> (or to a bitset	4070	A typical way to use this symbol is to define it to C<0> (or to a bitset
3900	with some broad features you want) and then selectively re-enable	4071	with some broad features you want) and then selectively re-enable
3901	additional parts you want, for example if you want everything minimal,	4072	additional parts you want, for example if you want everything minimal,
3902	but multiple event loop support, async and child watchers and the poll	4073	but multiple event loop support, async and child watchers and the poll
…		…
3915		4086
3916	=item C<1> - faster/larger code	4087	=item C<1> - faster/larger code
3917		4088
3918	Use larger code to speed up some operations.	4089	Use larger code to speed up some operations.
3919		4090
3920	Currently this is used to override some inlining decisions (enlarging the roughly	4091	Currently this is used to override some inlining decisions (enlarging the
3921	30% code size on amd64.	4092	code size by roughly 30% on amd64).
3922		4093
3923	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
3924	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
3925	assertions.	4096	assertions.
3926		4097
3927	=item C<2> - faster/larger data structures	4098	=item C<2> - faster/larger data structures
3928		4099
3929	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
3930	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
3931	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
3932	runtime.	4103	runtime.
3933		4104
3934	=item C<4> - full API configuration	4105	=item C<4> - full API configuration
3935		4106
3936	This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and	4107	This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and
3937	enables multiplicity (C<EV_MULTIPLICITY>=1).	4108	enables multiplicity (C<EV_MULTIPLICITY>=1).
3938		4109
		4110	=item C<8> - full API
		4111
3939	It also enables a lot of the "lesser used" core API functions. See C<ev.h>	4112	This enables a lot of the "lesser used" API functions. See C<ev.h> for
3940	for details on which parts of the API are still available without this	4113	details on which parts of the API are still available without this
3941	feature, and do not complain if this subset changes over time.	4114	feature, and do not complain if this subset changes over time.
3942		4115
3943	=item C<8> - enable all optional watcher types	4116	=item C<16> - enable all optional watcher types
3944		4117
3945	Enables all optional watcher types. If you want to selectively enable	4118	Enables all optional watcher types. If you want to selectively enable
3946	only some watcher types other than I/O and timers (e.g. prepare,	4119	only some watcher types other than I/O and timers (e.g. prepare,
3947	embed, async, child...) you can enable them manually by defining	4120	embed, async, child...) you can enable them manually by defining
3948	C<EV_watchertype_ENABLE> to C<1> instead.	4121	C<EV_watchertype_ENABLE> to C<1> instead.
3949		4122
3950	=item C<16> - enable all backends	4123	=item C<32> - enable all backends
3951		4124
3952	This enables all backends - without this feature, you need to enable at	4125	This enables all backends - without this feature, you need to enable at
3953	least one backend manually (C<EV_USE_SELECT> is a good choice).	4126	least one backend manually (C<EV_USE_SELECT> is a good choice).
3954		4127
3955	=item C<32> - enable OS-specific "helper" APIs	4128	=item C<64> - enable OS-specific "helper" APIs
3956		4129
3957	Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by	4130	Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by
3958	default.	4131	default.
3959		4132
3960	=back	4133	=back
3961		4134
3962	Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0>	4135	Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0>
3963	reduces the compiled size of libev from 24.7Kb to 6.5Kb on my GNU/Linux	4136	reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb
3964	amd64 system, while still giving you I/O watchers, timers and monotonic	4137	code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O
3965	clock support.	4138	watchers, timers and monotonic clock support.
3966		4139
3967	With an intelligent-enough linker (gcc+binutils are intelligent enough	4140	With an intelligent-enough linker (gcc+binutils are intelligent enough
3968	when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by	4141	when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by
3969	your program might be left out as well - a binary starting a timer and an	4142	your program might be left out as well - a binary starting a timer and an
3970	I/O watcher then might come out at only 5Kb.	4143	I/O watcher then might come out at only 5Kb.
3971		4144
3972	=item EV_AVOID_STDIO	4145	=item EV_AVOID_STDIO
3973		4146
3974	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
3975	functions (printf, scanf, perror etc.). This will increase the codesize	4148	functions (printf, scanf, perror etc.). This will increase the code size
3976	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
3977	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
3978	big.	4151	big.
3979		4152
3980	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
…		…
3984		4157
3985	The highest supported signal number, +1 (or, the number of	4158	The highest supported signal number, +1 (or, the number of
3986	signals): Normally, libev tries to deduce the maximum number of signals	4159	signals): Normally, libev tries to deduce the maximum number of signals
3987	automatically, but sometimes this fails, in which case it can be	4160	automatically, but sometimes this fails, in which case it can be
3988	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
3989	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
3990	statically allocates some 12-24 bytes per signal number.	4163	statically allocates some 12-24 bytes per signal number.
3991		4164
3992	=item EV_PID_HASHSIZE	4165	=item EV_PID_HASHSIZE
3993		4166
3994	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
…		…
4026	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
4027	will be C<0>.	4200	will be C<0>.
4028		4201
4029	=item EV_VERIFY	4202	=item EV_VERIFY
4030		4203
4031	Controls how much internal verification (see C<ev_loop_verify ()>) will	4204	Controls how much internal verification (see C<ev_verify ()>) will
4032	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
4033	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
4034	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
4035	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
4036	verification code will be called very frequently, which will slow down	4209	verification code will be called very frequently, which will slow down
…		…
4040	will be C<0>.	4213	will be C<0>.
4041		4214
4042	=item EV_COMMON	4215	=item EV_COMMON
4043		4216
4044	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
4045	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
4046	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,
4047	though, and it must be identical each time.	4220	though, and it must be identical each time.
4048		4221
4049	For example, the perl EV module uses something like this:	4222	For example, the perl EV module uses something like this:
4050		4223
…		…
4103	file.	4276	file.
4104		4277
4105	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	4278	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
4106	that everybody includes and which overrides some configure choices:	4279	that everybody includes and which overrides some configure choices:
4107		4280
4108	#define EV_FEATURES 0	4281	#define EV_FEATURES 8
4109	#define EV_USE_SELECT 1	4282	#define EV_USE_SELECT 1
		4283	#define EV_PREPARE_ENABLE 1
		4284	#define EV_IDLE_ENABLE 1
		4285	#define EV_SIGNAL_ENABLE 1
		4286	#define EV_CHILD_ENABLE 1
		4287	#define EV_USE_STDEXCEPT 0
4110	#define EV_CONFIG_H <config.h>	4288	#define EV_CONFIG_H <config.h>
4111		4289
4112	#include "ev++.h"	4290	#include "ev++.h"
4113		4291
4114	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	4292	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
…		…
4246	userdata *u = ev_userdata (EV_A);	4424	userdata *u = ev_userdata (EV_A);
4247	pthread_mutex_lock (&u->lock);	4425	pthread_mutex_lock (&u->lock);
4248	}	4426	}
4249		4427
4250	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
4251	into C<ev_loop>:	4429	into C<ev_run>:
4252		4430
4253	void *	4431	void *
4254	l_run (void *thr_arg)	4432	l_run (void *thr_arg)
4255	{	4433	{
4256	struct ev_loop *loop = (struct ev_loop *)thr_arg;	4434	struct ev_loop *loop = (struct ev_loop *)thr_arg;
4257		4435
4258	l_acquire (EV_A);	4436	l_acquire (EV_A);
4259	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);	4437	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
4260	ev_loop (EV_A_ 0);	4438	ev_run (EV_A_ 0);
4261	l_release (EV_A);	4439	l_release (EV_A);
4262		4440
4263	return 0;	4441	return 0;
4264	}	4442	}
4265		4443
…		…
4317		4495
4318	=head3 COROUTINES	4496	=head3 COROUTINES
4319		4497
4320	Libev is very accommodating to coroutines ("cooperative threads"):	4498	Libev is very accommodating to coroutines ("cooperative threads"):
4321	libev fully supports nesting calls to its functions from different	4499	libev fully supports nesting calls to its functions from different
4322	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
4323	different coroutines, and switch freely between both coroutines running	4501	different coroutines, and switch freely between both coroutines running
4324	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
4325	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.
4326		4504
4327	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
4328	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
4329	they do not call any callbacks.	4507	they do not call any callbacks.
4330		4508
4331	=head2 COMPILER WARNINGS	4509	=head2 COMPILER WARNINGS
4332		4510
4333	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
…		…
4344	maintainable.	4522	maintainable.
4345		4523
4346	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
4347	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
4348	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
4349	warnings that resulted an extreme number of false positives. These have	4527	warnings that resulted in an extreme number of false positives. These have
4350	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
4351	such buggy versions.	4529	such buggy versions.
4352		4530
4353	While libev is written to generate as few warnings as possible,	4531	While libev is written to generate as few warnings as possible,
4354	"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
…		…
4390	I suggest using suppression lists.	4568	I suggest using suppression lists.
4391		4569
4392		4570
4393	=head1 PORTABILITY NOTES	4571	=head1 PORTABILITY NOTES
4394		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
4395	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS	4659	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
		4660
		4661	=head3 General issues
4396		4662
4397	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
4398	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
4399	model. Libev still offers limited functionality on this platform in	4665	model. Libev still offers limited functionality on this platform in
4400	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
4401	descriptors. This only applies when using Win32 natively, not when using	4667	descriptors. This only applies when using Win32 natively, not when using
4402	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.
4403		4671
4404	Lifting these limitations would basically require the full	4672	Lifting these limitations would basically require the full
4405	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,
4406	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
4407	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).
4408		4676
4409	There is no supported compilation method available on windows except	4677	There is no supported compilation method available on windows except
4410	embedding it into other applications.	4678	embedding it into other applications.
4411		4679
4412	Sensible signal handling is officially unsupported by Microsoft - libev	4680	Sensible signal handling is officially unsupported by Microsoft - libev
…		…
4440	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!):
4441		4709
4442	#include "evwrap.h"	4710	#include "evwrap.h"
4443	#include "ev.c"	4711	#include "ev.c"
4444		4712
4445	=over 4
4446
4447	=item The winsocket select function	4713	=head3 The winsocket C<select> function
4448		4714
4449	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
4450	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
4451	also extremely buggy). This makes select very inefficient, and also	4717	also extremely buggy). This makes select very inefficient, and also
4452	requires a mapping from file descriptors to socket handles (the Microsoft	4718	requires a mapping from file descriptors to socket handles (the Microsoft
…		…
4461	#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 */
4462		4728
4463	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
4464	complexity in the O(n²) range when using win32.	4730	complexity in the O(n²) range when using win32.
4465		4731
4466	=item Limited number of file descriptors	4732	=head3 Limited number of file descriptors
4467		4733
4468	Windows has numerous arbitrary (and low) limits on things.	4734	Windows has numerous arbitrary (and low) limits on things.
4469		4735
4470	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
4471	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
…		…
4486	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
4487	(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,
4488	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
4489	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.
4490		4756
4491	=back
4492
4493	=head2 PORTABILITY REQUIREMENTS	4757	=head2 PORTABILITY REQUIREMENTS
4494		4758
4495	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
4496	backend-specific APIs, libev relies on a few additional extensions:	4760	backend-specific APIs, libev relies on a few additional extensions:
4497		4761
…		…
4503	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
4504	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
4505	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
4506	callback: The watcher callbacks have different type signatures, but libev	4770	callback: The watcher callbacks have different type signatures, but libev
4507	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.
4508		4777
4509	=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
4510		4779
4511	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
4512	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
…		…
4535	watchers.	4804	watchers.
4536		4805
4537	=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
4538		4807
4539	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
4540	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
4541	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
4542	implementations implementing IEEE 754, which is basically all existing	4812	implementations using IEEE 754, which is basically all existing ones. With
4543	ones. With IEEE 754 doubles, you get microsecond accuracy until at least	4813	IEEE 754 doubles, you get microsecond accuracy until at least 2200.
4544	2200.
4545		4814
4546	=back	4815	=back
4547		4816
4548	If you know of other additional requirements drop me a note.	4817	If you know of other additional requirements drop me a note.
4549		4818
…		…
4617	involves iterating over all running async watchers or all signal numbers.	4886	involves iterating over all running async watchers or all signal numbers.
4618		4887
4619	=back	4888	=back
4620		4889
4621		4890
		4891	=head1 PORTING FROM LIBEV 3.X TO 4.X
		4892
		4893	The major version 4 introduced some incompatible changes to the API.
		4894
		4895	At the moment, the C<ev.h> header file provides compatibility definitions
		4896	for all changes, so most programs should still compile. The compatibility
		4897	layer might be removed in later versions of libev, so better update to the
		4898	new API early than late.
		4899
		4900	=over 4
		4901
		4902	=item C<EV_COMPAT3> backwards compatibility mechanism
		4903
		4904	The backward compatibility mechanism can be controlled by
		4905	C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING>
		4906	section.
		4907
		4908	=item C<ev_default_destroy> and C<ev_default_fork> have been removed
		4909
		4910	These calls can be replaced easily by their C<ev_loop_xxx> counterparts:
		4911
		4912	ev_loop_destroy (EV_DEFAULT_UC);
		4913	ev_loop_fork (EV_DEFAULT);
		4914
		4915	=item function/symbol renames
		4916
		4917	A number of functions and symbols have been renamed:
		4918
		4919	ev_loop => ev_run
		4920	EVLOOP_NONBLOCK => EVRUN_NOWAIT
		4921	EVLOOP_ONESHOT => EVRUN_ONCE
		4922
		4923	ev_unloop => ev_break
		4924	EVUNLOOP_CANCEL => EVBREAK_CANCEL
		4925	EVUNLOOP_ONE => EVBREAK_ONE
		4926	EVUNLOOP_ALL => EVBREAK_ALL
		4927
		4928	EV_TIMEOUT => EV_TIMER
		4929
		4930	ev_loop_count => ev_iteration
		4931	ev_loop_depth => ev_depth
		4932	ev_loop_verify => ev_verify
		4933
		4934	Most functions working on C<struct ev_loop> objects don't have an
		4935	C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and
		4936	associated constants have been renamed to not collide with the C<struct
		4937	ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme
		4938	as all other watcher types. Note that C<ev_loop_fork> is still called
		4939	C<ev_loop_fork> because it would otherwise clash with the C<ev_fork>
		4940	typedef.
		4941
		4942	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>
		4943
		4944	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different
		4945	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile
		4946	and work, but the library code will of course be larger.
		4947
		4948	=back
		4949
		4950
4622	=head1 GLOSSARY	4951	=head1 GLOSSARY
4623		4952
4624	=over 4	4953	=over 4
4625		4954
4626	=item active	4955	=item active
4627		4956
4628	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.
4629	an event loop) but not yet stopped (disassociated from the event loop).	4958	See L<WATCHER STATES> for details.
4630		4959
4631	=item application	4960	=item application
4632		4961
4633	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.
4634		4967
4635	=item callback	4968	=item callback
4636		4969
4637	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
4638	detected. Callbacks are being passed the event loop, the watcher that	4971	detected. Callbacks are being passed the event loop, the watcher that
4639	received the event, and the actual event bitset.	4972	received the event, and the actual event bitset.
4640		4973
4641	=item callback invocation	4974	=item callback/watcher invocation
4642		4975
4643	The act of calling the callback associated with a watcher.	4976	The act of calling the callback associated with a watcher.
4644		4977
4645	=item event	4978	=item event
4646		4979
4647	A change of state of some external event, such as data now being available	4980	A change of state of some external event, such as data now being available
4648	for reading on a file descriptor, time having passed or simply not having	4981	for reading on a file descriptor, time having passed or simply not having
4649	any other events happening anymore.	4982	any other events happening anymore.
4650		4983
4651	In libev, events are represented as single bits (such as C<EV_READ> or	4984	In libev, events are represented as single bits (such as C<EV_READ> or
4652	C<EV_TIMEOUT>).	4985	C<EV_TIMER>).
4653		4986
4654	=item event library	4987	=item event library
4655		4988
4656	A software package implementing an event model and loop.	4989	A software package implementing an event model and loop.
4657		4990
…		…
4665	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
4666	watchers and events.	4999	watchers and events.
4667		5000
4668	=item pending	5001	=item pending
4669		5002
4670	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
4671	and stops being pending as soon as the watcher will be invoked or its	5004	detected. See L<WATCHER STATES> for details.
4672	pending status is explicitly cleared by the application.
4673
4674	A watcher can be pending, but not active. Stopping a watcher also clears
4675	its pending status.
4676		5005
4677	=item real time	5006	=item real time
4678		5007
4679	The physical time that is observed. It is apparently strictly monotonic :)	5008	The physical time that is observed. It is apparently strictly monotonic :)
4680		5009
…		…
4687	=item watcher	5016	=item watcher
4688		5017
4689	A data structure that describes interest in certain events. Watchers need	5018	A data structure that describes interest in certain events. Watchers need
4690	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.
4691		5020
4692	=item watcher invocation
4693
4694	The act of calling the callback associated with a watcher.
4695
4696	=back	5021	=back
4697		5022
4698	=head1 AUTHOR	5023	=head1 AUTHOR
4699		5024
4700	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.
4701		5027

Diff Legend

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