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Revision 1.286 by root, Tue Mar 16 00:26:41 2010 UTC vs.
Revision 1.351 by root, Mon Jan 10 14:24:26 2011 UTC

…		…
26	puts ("stdin ready");	26	puts ("stdin ready");
27	// for one-shot events, one must manually stop the watcher	27	// for one-shot events, one must manually stop the watcher
28	// with its corresponding stop function.	28	// with its corresponding stop function.
29	ev_io_stop (EV_A_ w);	29	ev_io_stop (EV_A_ w);
30		30
31	// this causes all nested ev_loop's to stop iterating	31	// this causes all nested ev_run's to stop iterating
32	ev_unloop (EV_A_ EVUNLOOP_ALL);	32	ev_break (EV_A_ EVBREAK_ALL);
33	}	33	}
34		34
35	// another callback, this time for a time-out	35	// another callback, this time for a time-out
36	static void	36	static void
37	timeout_cb (EV_P_ ev_timer *w, int revents)	37	timeout_cb (EV_P_ ev_timer *w, int revents)
38	{	38	{
39	puts ("timeout");	39	puts ("timeout");
40	// this causes the innermost ev_loop to stop iterating	40	// this causes the innermost ev_run to stop iterating
41	ev_unloop (EV_A_ EVUNLOOP_ONE);	41	ev_break (EV_A_ EVBREAK_ONE);
42	}	42	}
43		43
44	int	44	int
45	main (void)	45	main (void)
46	{	46	{
47	// use the default event loop unless you have special needs	47	// use the default event loop unless you have special needs
48	struct ev_loop *loop = ev_default_loop (0);	48	struct ev_loop *loop = EV_DEFAULT;
49		49
50	// initialise an io watcher, then start it	50	// initialise an io watcher, then start it
51	// this one will watch for stdin to become readable	51	// this one will watch for stdin to become readable
52	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);	52	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);
53	ev_io_start (loop, &stdin_watcher);	53	ev_io_start (loop, &stdin_watcher);
…		…
56	// simple non-repeating 5.5 second timeout	56	// simple non-repeating 5.5 second timeout
57	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);	57	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
58	ev_timer_start (loop, &timeout_watcher);	58	ev_timer_start (loop, &timeout_watcher);
59		59
60	// now wait for events to arrive	60	// now wait for events to arrive
61	ev_loop (loop, 0);	61	ev_run (loop, 0);
62		62
63	// unloop was called, so exit	63	// unloop was called, so exit
64	return 0;	64	return 0;
65	}	65	}
66		66
…		…
75	While this document tries to be as complete as possible in documenting	75	While this document tries to be as complete as possible in documenting
76	libev, its usage and the rationale behind its design, it is not a tutorial	76	libev, its usage and the rationale behind its design, it is not a tutorial
77	on event-based programming, nor will it introduce event-based programming	77	on event-based programming, nor will it introduce event-based programming
78	with libev.	78	with libev.
79		79
80	Familarity with event based programming techniques in general is assumed	80	Familiarity with event based programming techniques in general is assumed
81	throughout this document.	81	throughout this document.
		82
		83	=head1 WHAT TO READ WHEN IN A HURRY
		84
		85	This manual tries to be very detailed, but unfortunately, this also makes
		86	it very long. If you just want to know the basics of libev, I suggest
		87	reading L<ANATOMY OF A WATCHER>, then the L<EXAMPLE PROGRAM> above and
		88	look up the missing functions in L<GLOBAL FUNCTIONS> and the C<ev_io> and
		89	C<ev_timer> sections in L<WATCHER TYPES>.
82		90
83	=head1 ABOUT LIBEV	91	=head1 ABOUT LIBEV
84		92
85	Libev is an event loop: you register interest in certain events (such as a	93	Libev is an event loop: you register interest in certain events (such as a
86	file descriptor being readable or a timeout occurring), and it will manage	94	file descriptor being readable or a timeout occurring), and it will manage
…		…
124	this argument.	132	this argument.
125		133
126	=head2 TIME REPRESENTATION	134	=head2 TIME REPRESENTATION
127		135
128	Libev represents time as a single floating point number, representing	136	Libev represents time as a single floating point number, representing
129	the (fractional) number of seconds since the (POSIX) epoch (somewhere	137	the (fractional) number of seconds since the (POSIX) epoch (in practice
130	near the beginning of 1970, details are complicated, don't ask). This	138	somewhere near the beginning of 1970, details are complicated, don't
131	type is called C<ev_tstamp>, which is what you should use too. It usually	139	ask). This type is called C<ev_tstamp>, which is what you should use
132	aliases to the C<double> type in C. When you need to do any calculations	140	too. It usually aliases to the C<double> type in C. When you need to do
133	on it, you should treat it as some floating point value. Unlike the name	141	any calculations on it, you should treat it as some floating point value.
		142
134	component C<stamp> might indicate, it is also used for time differences	143	Unlike the name component C<stamp> might indicate, it is also used for
135	throughout libev.	144	time differences (e.g. delays) throughout libev.
136		145
137	=head1 ERROR HANDLING	146	=head1 ERROR HANDLING
138		147
139	Libev knows three classes of errors: operating system errors, usage errors	148	Libev knows three classes of errors: operating system errors, usage errors
140	and internal errors (bugs).	149	and internal errors (bugs).
…		…
164		173
165	=item ev_tstamp ev_time ()	174	=item ev_tstamp ev_time ()
166		175
167	Returns the current time as libev would use it. Please note that the	176	Returns the current time as libev would use it. Please note that the
168	C<ev_now> function is usually faster and also often returns the timestamp	177	C<ev_now> function is usually faster and also often returns the timestamp
169	you actually want to know.	178	you actually want to know. Also interesting is the combination of
		179	C<ev_update_now> and C<ev_now>.
170		180
171	=item ev_sleep (ev_tstamp interval)	181	=item ev_sleep (ev_tstamp interval)
172		182
173	Sleep for the given interval: The current thread will be blocked until	183	Sleep for the given interval: The current thread will be blocked until
174	either it is interrupted or the given time interval has passed. Basically	184	either it is interrupted or the given time interval has passed. Basically
…		…
191	as this indicates an incompatible change. Minor versions are usually	201	as this indicates an incompatible change. Minor versions are usually
192	compatible to older versions, so a larger minor version alone is usually	202	compatible to older versions, so a larger minor version alone is usually
193	not a problem.	203	not a problem.
194		204
195	Example: Make sure we haven't accidentally been linked against the wrong	205	Example: Make sure we haven't accidentally been linked against the wrong
196	version.	206	version (note, however, that this will not detect other ABI mismatches,
		207	such as LFS or reentrancy).
197		208
198	assert (("libev version mismatch",	209	assert (("libev version mismatch",
199	ev_version_major () == EV_VERSION_MAJOR	210	ev_version_major () == EV_VERSION_MAJOR
200	&& ev_version_minor () >= EV_VERSION_MINOR));	211	&& ev_version_minor () >= EV_VERSION_MINOR));
201		212
…		…
212	assert (("sorry, no epoll, no sex",	223	assert (("sorry, no epoll, no sex",
213	ev_supported_backends () & EVBACKEND_EPOLL));	224	ev_supported_backends () & EVBACKEND_EPOLL));
214		225
215	=item unsigned int ev_recommended_backends ()	226	=item unsigned int ev_recommended_backends ()
216		227
217	Return the set of all backends compiled into this binary of libev and also	228	Return the set of all backends compiled into this binary of libev and
218	recommended for this platform. This set is often smaller than the one	229	also recommended for this platform, meaning it will work for most file
		230	descriptor types. This set is often smaller than the one returned by
219	returned by C<ev_supported_backends>, as for example kqueue is broken on	231	C<ev_supported_backends>, as for example kqueue is broken on most BSDs
220	most BSDs and will not be auto-detected unless you explicitly request it	232	and will not be auto-detected unless you explicitly request it (assuming
221	(assuming you know what you are doing). This is the set of backends that	233	you know what you are doing). This is the set of backends that libev will
222	libev will probe for if you specify no backends explicitly.	234	probe for if you specify no backends explicitly.
223		235
224	=item unsigned int ev_embeddable_backends ()	236	=item unsigned int ev_embeddable_backends ()
225		237
226	Returns the set of backends that are embeddable in other event loops. This	238	Returns the set of backends that are embeddable in other event loops. This
227	is the theoretical, all-platform, value. To find which backends	239	value is platform-specific but can include backends not available on the
228	might be supported on the current system, you would need to look at	240	current system. To find which embeddable backends might be supported on
229	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for	241	the current system, you would need to look at C<ev_embeddable_backends ()
230	recommended ones.	242	& ev_supported_backends ()>, likewise for recommended ones.
231		243
232	See the description of C<ev_embed> watchers for more info.	244	See the description of C<ev_embed> watchers for more info.
233		245
234	=item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT]	246	=item ev_set_allocator (void *(*cb)(void *ptr, long size))
235		247
236	Sets the allocation function to use (the prototype is similar - the	248	Sets the allocation function to use (the prototype is similar - the
237	semantics are identical to the C<realloc> C89/SuS/POSIX function). It is	249	semantics are identical to the C<realloc> C89/SuS/POSIX function). It is
238	used to allocate and free memory (no surprises here). If it returns zero	250	used to allocate and free memory (no surprises here). If it returns zero
239	when memory needs to be allocated (C<size != 0>), the library might abort	251	when memory needs to be allocated (C<size != 0>), the library might abort
…		…
265	}	277	}
266		278
267	...	279	...
268	ev_set_allocator (persistent_realloc);	280	ev_set_allocator (persistent_realloc);
269		281
270	=item ev_set_syserr_cb (void (*cb)(const char *msg)); [NOT REENTRANT]	282	=item ev_set_syserr_cb (void (*cb)(const char *msg))
271		283
272	Set the callback function to call on a retryable system call error (such	284	Set the callback function to call on a retryable system call error (such
273	as failed select, poll, epoll_wait). The message is a printable string	285	as failed select, poll, epoll_wait). The message is a printable string
274	indicating the system call or subsystem causing the problem. If this	286	indicating the system call or subsystem causing the problem. If this
275	callback is set, then libev will expect it to remedy the situation, no	287	callback is set, then libev will expect it to remedy the situation, no
…		…
287	}	299	}
288		300
289	...	301	...
290	ev_set_syserr_cb (fatal_error);	302	ev_set_syserr_cb (fatal_error);
291		303
		304	=item ev_feed_signal (int signum)
		305
		306	This function can be used to "simulate" a signal receive. It is completely
		307	safe to call this function at any time, from any context, including signal
		308	handlers or random threads.
		309
		310	Its main use is to customise signal handling in your process, especially
		311	in the presence of threads. For example, you could block signals
		312	by default in all threads (and specifying C<EVFLAG_NOSIGMASK> when
		313	creating any loops), and in one thread, use C<sigwait> or any other
		314	mechanism to wait for signals, then "deliver" them to libev by calling
		315	C<ev_feed_signal>.
		316
292	=back	317	=back
293		318
294	=head1 FUNCTIONS CONTROLLING THE EVENT LOOP	319	=head1 FUNCTIONS CONTROLLING EVENT LOOPS
295		320
296	An event loop is described by a C<struct ev_loop *> (the C<struct>	321	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>	322	I<not> optional in this case unless libev 3 compatibility is disabled, as
298	I<function>).	323	libev 3 had an C<ev_loop> function colliding with the struct name).
299		324
300	The library knows two types of such loops, the I<default> loop, which	325	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	326	supports child process events, and dynamically created event loops which
302	not.	327	do not.
303		328
304	=over 4	329	=over 4
305		330
306	=item struct ev_loop *ev_default_loop (unsigned int flags)	331	=item struct ev_loop *ev_default_loop (unsigned int flags)
307		332
308	This will initialise the default event loop if it hasn't been initialised	333	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	334	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	335	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).	336	C<ev_loop_new>.
		337
		338	If the default loop is already initialised then this function simply
		339	returns it (and ignores the flags. If that is troubling you, check
		340	C<ev_backend ()> afterwards). Otherwise it will create it with the given
		341	flags, which should almost always be C<0>, unless the caller is also the
		342	one calling C<ev_run> or otherwise qualifies as "the main program".
312		343
313	If you don't know what event loop to use, use the one returned from this	344	If you don't know what event loop to use, use the one returned from this
314	function.	345	function (or via the C<EV_DEFAULT> macro).
315		346
316	Note that this function is I<not> thread-safe, so if you want to use it	347	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,	348	from multiple threads, you have to employ some kind of mutex (note also
318	as loops cannot be shared easily between threads anyway).	349	that this case is unlikely, as loops cannot be shared easily between
		350	threads anyway).
319		351
320	The default loop is the only loop that can handle C<ev_signal> and	352	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	353	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	354	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	355	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	356	C<SIGCHLD> signal handler I<after> calling C<ev_default_init>.
325	C<ev_default_init>.	357
		358	Example: This is the most typical usage.
		359
		360	if (!ev_default_loop (0))
		361	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
		362
		363	Example: Restrict libev to the select and poll backends, and do not allow
		364	environment settings to be taken into account:
		365
		366	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
		367
		368	=item struct ev_loop *ev_loop_new (unsigned int flags)
		369
		370	This will create and initialise a new event loop object. If the loop
		371	could not be initialised, returns false.
		372
		373	This function is thread-safe, and one common way to use libev with
		374	threads is indeed to create one loop per thread, and using the default
		375	loop in the "main" or "initial" thread.
326		376
327	The flags argument can be used to specify special behaviour or specific	377	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>).	378	backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>).
329		379
330	The following flags are supported:	380	The following flags are supported:
…		…
345	useful to try out specific backends to test their performance, or to work	395	useful to try out specific backends to test their performance, or to work
346	around bugs.	396	around bugs.
347		397
348	=item C<EVFLAG_FORKCHECK>	398	=item C<EVFLAG_FORKCHECK>
349		399
350	Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after	400	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	401	make libev check for a fork in each iteration by enabling this flag.
352	enabling this flag.
353		402
354	This works by calling C<getpid ()> on every iteration of the loop,	403	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	404	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	405	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	406	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence
…		…
366	environment variable.	415	environment variable.
367		416
368	=item C<EVFLAG_NOINOTIFY>	417	=item C<EVFLAG_NOINOTIFY>
369		418
370	When this flag is specified, then libev will not attempt to use the	419	When this flag is specified, then libev will not attempt to use the
371	I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and	420	I<inotify> API for its C<ev_stat> watchers. Apart from debugging and
372	testing, this flag can be useful to conserve inotify file descriptors, as	421	testing, this flag can be useful to conserve inotify file descriptors, as
373	otherwise each loop using C<ev_stat> watchers consumes one inotify handle.	422	otherwise each loop using C<ev_stat> watchers consumes one inotify handle.
374		423
375	=item C<EVFLAG_SIGNALFD>	424	=item C<EVFLAG_SIGNALFD>
376		425
377	When this flag is specified, then libev will attempt to use the	426	When this flag is specified, then libev will attempt to use the
378	I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This API	427	I<signalfd> API for its C<ev_signal> (and C<ev_child>) watchers. This API
379	delivers signals synchronously, which makes it both faster and might make	428	delivers signals synchronously, which makes it both faster and might make
380	it possible to get the queued signal data. It can also simplify signal	429	it possible to get the queued signal data. It can also simplify signal
381	handling with threads, as long as you properly block signals in your	430	handling with threads, as long as you properly block signals in your
382	threads that are not interested in handling them.	431	threads that are not interested in handling them.
383		432
384	Signalfd will not be used by default as this changes your signal mask, and	433	Signalfd will not be used by default as this changes your signal mask, and
385	there are a lot of shoddy libraries and programs (glib's threadpool for	434	there are a lot of shoddy libraries and programs (glib's threadpool for
386	example) that can't properly initialise their signal masks.	435	example) that can't properly initialise their signal masks.
		436
		437	=item C<EVFLAG_NOSIGMASK>
		438
		439	When this flag is specified, then libev will avoid to modify the signal
		440	mask. Specifically, this means you ahve to make sure signals are unblocked
		441	when you want to receive them.
		442
		443	This behaviour is useful when you want to do your own signal handling, or
		444	want to handle signals only in specific threads and want to avoid libev
		445	unblocking the signals.
		446
		447	This flag's behaviour will become the default in future versions of libev.
387		448
388	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	449	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
389		450
390	This is your standard select(2) backend. Not I<completely> standard, as	451	This is your standard select(2) backend. Not I<completely> standard, as
391	libev tries to roll its own fd_set with no limits on the number of fds,	452	libev tries to roll its own fd_set with no limits on the number of fds,
…		…
427	epoll scales either O(1) or O(active_fds).	488	epoll scales either O(1) or O(active_fds).
428		489
429	The epoll mechanism deserves honorable mention as the most misdesigned	490	The epoll mechanism deserves honorable mention as the most misdesigned
430	of the more advanced event mechanisms: mere annoyances include silently	491	of the more advanced event mechanisms: mere annoyances include silently
431	dropping file descriptors, requiring a system call per change per file	492	dropping file descriptors, requiring a system call per change per file
432	descriptor (and unnecessary guessing of parameters), problems with dup and	493	descriptor (and unnecessary guessing of parameters), problems with dup,
		494	returning before the timeout value, resulting in additional iterations
		495	(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	496	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	497	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	498	set, which can take considerable time (one syscall per file descriptor)
436	hard to detect.	499	and is of course hard to detect.
437		500
438	Epoll is also notoriously buggy - embedding epoll fds I<should> work, but	501	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	502	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	503	I<different> file descriptors (even already closed ones, so one cannot
441	even remove them from the set) than registered in the set (especially	504	even remove them from the set) than registered in the set (especially
442	on SMP systems). Libev tries to counter these spurious notifications by	505	on SMP systems). Libev tries to counter these spurious notifications by
443	employing an additional generation counter and comparing that against the	506	employing an additional generation counter and comparing that against the
444	events to filter out spurious ones, recreating the set when required.	507	events to filter out spurious ones, recreating the set when required. Last
		508	not least, it also refuses to work with some file descriptors which work
		509	perfectly fine with C<select> (files, many character devices...).
		510
		511	Epoll is truly the train wreck analog among event poll mechanisms.
445		512
446	While stopping, setting and starting an I/O watcher in the same iteration	513	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	514	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	515	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	516	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed
…		…
515	=item C<EVBACKEND_PORT> (value 32, Solaris 10)	582	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
516		583
517	This uses the Solaris 10 event port mechanism. As with everything on Solaris,	584	This uses the Solaris 10 event port mechanism. As with everything on Solaris,
518	it's really slow, but it still scales very well (O(active_fds)).	585	it's really slow, but it still scales very well (O(active_fds)).
519		586
520	Please note that Solaris event ports can deliver a lot of spurious
521	notifications, so you need to use non-blocking I/O or other means to avoid
522	blocking when no data (or space) is available.
523
524	While this backend scales well, it requires one system call per active	587	While this backend scales well, it requires one system call per active
525	file descriptor per loop iteration. For small and medium numbers of file	588	file descriptor per loop iteration. For small and medium numbers of file
526	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend	589	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend
527	might perform better.	590	might perform better.
528		591
529	On the positive side, with the exception of the spurious readiness	592	On the positive side, this backend actually performed fully to
530	notifications, this backend actually performed fully to specification
531	in all tests and is fully embeddable, which is a rare feat among the	593	specification in all tests and is fully embeddable, which is a rare feat
532	OS-specific backends (I vastly prefer correctness over speed hacks).	594	among the OS-specific backends (I vastly prefer correctness over speed
		595	hacks).
		596
		597	On the negative side, the interface is I<bizarre>, with the event polling
		598	function sometimes returning events to the caller even though an error
		599	occured, but with no indication whether it has done so or not (yes, it's
		600	even documented that way) - deadly for edge-triggered interfaces, but
		601	fortunately libev seems to be able to work around it.
533		602
534	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as	603	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as
535	C<EVBACKEND_POLL>.	604	C<EVBACKEND_POLL>.
536		605
537	=item C<EVBACKEND_ALL>	606	=item C<EVBACKEND_ALL>
538		607
539	Try all backends (even potentially broken ones that wouldn't be tried	608	Try all backends (even potentially broken ones that wouldn't be tried
540	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as	609	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as
541	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.	610	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.
542		611
543	It is definitely not recommended to use this flag.	612	It is definitely not recommended to use this flag, use whatever
		613	C<ev_recommended_backends ()> returns, or simply do not specify a backend
		614	at all.
		615
		616	=item C<EVBACKEND_MASK>
		617
		618	Not a backend at all, but a mask to select all backend bits from a
		619	C<flags> value, in case you want to mask out any backends from a flags
		620	value (e.g. when modifying the C<LIBEV_FLAGS> environment variable).
544		621
545	=back	622	=back
546		623
547	If one or more of the backend flags are or'ed into the flags value,	624	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	625	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	626	here). If none are specified, all backends in C<ev_recommended_backends
550	()> will be tried.	627	()> will be tried.
551		628
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.	629	Example: Try to create a event loop that uses epoll and nothing else.
581		630
582	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	631	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
583	if (!epoller)	632	if (!epoller)
584	fatal ("no epoll found here, maybe it hides under your chair");	633	fatal ("no epoll found here, maybe it hides under your chair");
585		634
		635	Example: Use whatever libev has to offer, but make sure that kqueue is
		636	used if available.
		637
		638	struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE);
		639
586	=item ev_default_destroy ()	640	=item ev_loop_destroy (loop)
587		641
588	Destroys the default loop again (frees all memory and kernel state	642	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	643	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	644	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>	645	responsibility to either stop all watchers cleanly yourself I<before>
592	calling this function, or cope with the fact afterwards (which is usually	646	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	647	the easiest thing, you can just ignore the watchers and/or C<free ()> them
…		…
595		649
596	Note that certain global state, such as signal state (and installed signal	650	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	651	handlers), will not be freed by this function, and related watchers (such
598	as signal and child watchers) would need to be stopped manually.	652	as signal and child watchers) would need to be stopped manually.
599		653
600	In general it is not advisable to call this function except in the	654	This function is normally used on loop objects allocated by
601	rare occasion where you really need to free e.g. the signal handling	655	C<ev_loop_new>, but it can also be used on the default loop returned by
		656	C<ev_default_loop>, in which case it is not thread-safe.
		657
		658	Note that it is not advisable to call this function on the default loop
		659	except in the rare occasion where you really need to free its resources.
602	pipe fds. If you need dynamically allocated loops it is better to use	660	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>.	661	and C<ev_loop_destroy>.
604		662
605	=item ev_loop_destroy (loop)	663	=item ev_loop_fork (loop)
606		664
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	665	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	666	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	667	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	668	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	669	child before resuming or calling C<ev_run>.
617	functions, and it will only take effect at the next C<ev_loop> iteration.	670
		671	Again, you I<have> to call it on I<any> loop that you want to re-use after
		672	a fork, I<even if you do not plan to use the loop in the parent>. This is
		673	because some kernel interfaces *cough* I<kqueue> *cough* do funny things
		674	during fork.
618		675
619	On the other hand, you only need to call this function in the child	676	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	677	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.	678	you just fork+exec or create a new loop in the child, you don't have to
		679	call it at all (in fact, C<epoll> is so badly broken that it makes a
		680	difference, but libev will usually detect this case on its own and do a
		681	costly reset of the backend).
622		682
623	The function itself is quite fast and it's usually not a problem to call	683	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	684	it just in case after a fork.
625	quite nicely into a call to C<pthread_atfork>:
626		685
		686	Example: Automate calling C<ev_loop_fork> on the default loop when
		687	using pthreads.
		688
		689	static void
		690	post_fork_child (void)
		691	{
		692	ev_loop_fork (EV_DEFAULT);
		693	}
		694
		695	...
627	pthread_atfork (0, 0, ev_default_fork);	696	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		697
636	=item int ev_is_default_loop (loop)	698	=item int ev_is_default_loop (loop)
637		699
638	Returns true when the given loop is, in fact, the default loop, and false	700	Returns true when the given loop is, in fact, the default loop, and false
639	otherwise.	701	otherwise.
640		702
641	=item unsigned int ev_loop_count (loop)	703	=item unsigned int ev_iteration (loop)
642		704
643	Returns the count of loop iterations for the loop, which is identical to	705	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	706	to the number of times libev did poll for new events. It starts at C<0>
645	happily wraps around with enough iterations.	707	and happily wraps around with enough iterations.
646		708
647	This value can sometimes be useful as a generation counter of sorts (it	709	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	710	"ticks" the number of loop iterations), as it roughly corresponds with
649	C<ev_prepare> and C<ev_check> calls.	711	C<ev_prepare> and C<ev_check> calls - and is incremented between the
		712	prepare and check phases.
650		713
651	=item unsigned int ev_loop_depth (loop)	714	=item unsigned int ev_depth (loop)
652		715
653	Returns the number of times C<ev_loop> was entered minus the number of	716	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.	717	times C<ev_run> was exited normally, in other words, the recursion depth.
655		718
656	Outside C<ev_loop>, this number is zero. In a callback, this number is	719	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),	720	C<1>, unless C<ev_run> was invoked recursively (or from another thread),
658	in which case it is higher.	721	in which case it is higher.
659		722
660	Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread	723	Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread,
661	etc.), doesn't count as exit.	724	throwing an exception etc.), doesn't count as "exit" - consider this
		725	as a hint to avoid such ungentleman-like behaviour unless it's really
		726	convenient, in which case it is fully supported.
662		727
663	=item unsigned int ev_backend (loop)	728	=item unsigned int ev_backend (loop)
664		729
665	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	730	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
666	use.	731	use.
…		…
675		740
676	=item ev_now_update (loop)	741	=item ev_now_update (loop)
677		742
678	Establishes the current time by querying the kernel, updating the time	743	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	744	returned by C<ev_now ()> in the progress. This is a costly operation and
680	is usually done automatically within C<ev_loop ()>.	745	is usually done automatically within C<ev_run ()>.
681		746
682	This function is rarely useful, but when some event callback runs for a	747	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	748	very long time without entering the event loop, updating libev's idea of
684	the current time is a good idea.	749	the current time is a good idea.
685		750
…		…
687		752
688	=item ev_suspend (loop)	753	=item ev_suspend (loop)
689		754
690	=item ev_resume (loop)	755	=item ev_resume (loop)
691		756
692	These two functions suspend and resume a loop, for use when the loop is	757	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.	758	loop is not used for a while and timeouts should not be processed.
694		759
695	A typical use case would be an interactive program such as a game: When	760	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	761	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	762	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>	763	the program was suspended. This can be achieved by calling C<ev_suspend>
…		…
700	C<ev_resume> directly afterwards to resume timer processing.	765	C<ev_resume> directly afterwards to resume timer processing.
701		766
702	Effectively, all C<ev_timer> watchers will be delayed by the time spend	767	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	768	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	769	will be rescheduled (that is, they will lose any events that would have
705	occured while suspended).	770	occurred while suspended).
706		771
707	After calling C<ev_suspend> you B<must not> call I<any> function on the	772	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>	773	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>.	774	without a previous call to C<ev_suspend>.
710		775
711	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the	776	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the
712	event loop time (see C<ev_now_update>).	777	event loop time (see C<ev_now_update>).
713		778
714	=item ev_loop (loop, int flags)	779	=item ev_run (loop, int flags)
715		780
716	Finally, this is it, the event handler. This function usually is called	781	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	782	after you have initialised all your watchers and you want to start
718	handling events.	783	handling events. It will ask the operating system for any new events, call
		784	the watcher callbacks, an then repeat the whole process indefinitely: This
		785	is why event loops are called I<loops>.
719		786
720	If the flags argument is specified as C<0>, it will not return until	787	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.	788	until either no event watchers are active anymore or C<ev_break> was
		789	called.
722		790
723	Please note that an explicit C<ev_unloop> is usually better than	791	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	792	relying on all watchers to be stopped when deciding when a program has
725	finished (especially in interactive programs), but having a program	793	finished (especially in interactive programs), but having a program
726	that automatically loops as long as it has to and no longer by virtue	794	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	795	of relying on its watchers stopping correctly, that is truly a thing of
728	beauty.	796	beauty.
729		797
		798	This function is also I<mostly> exception-safe - you can break out of
		799	a C<ev_run> call by calling C<longjmp> in a callback, throwing a C++
		800	exception and so on. This does not decrement the C<ev_depth> value, nor
		801	will it clear any outstanding C<EVBREAK_ONE> breaks.
		802
730	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle	803	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	804	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	805	block your process in case there are no events and will return after one
733	the loop.	806	iteration of the loop. This is sometimes useful to poll and handle new
		807	events while doing lengthy calculations, to keep the program responsive.
734		808
735	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if	809	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	810	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	811	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	812	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	813	user-registered callback will be called), and will return after one
740	iteration of the loop.	814	iteration of the loop.
741		815
742	This is useful if you are waiting for some external event in conjunction	816	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	817	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	818	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.	819	usually a better approach for this kind of thing.
746		820
747	Here are the gory details of what C<ev_loop> does:	821	Here are the gory details of what C<ev_run> does:
748		822
		823	- Increment loop depth.
		824	- Reset the ev_break status.
749	- Before the first iteration, call any pending watchers.	825	- Before the first iteration, call any pending watchers.
		826	LOOP:
750	* If EVFLAG_FORKCHECK was used, check for a fork.	827	- If EVFLAG_FORKCHECK was used, check for a fork.
751	- If a fork was detected (by any means), queue and call all fork watchers.	828	- If a fork was detected (by any means), queue and call all fork watchers.
752	- Queue and call all prepare watchers.	829	- Queue and call all prepare watchers.
		830	- If ev_break was called, goto FINISH.
753	- If we have been forked, detach and recreate the kernel state	831	- If we have been forked, detach and recreate the kernel state
754	as to not disturb the other process.	832	as to not disturb the other process.
755	- Update the kernel state with all outstanding changes.	833	- Update the kernel state with all outstanding changes.
756	- Update the "event loop time" (ev_now ()).	834	- Update the "event loop time" (ev_now ()).
757	- Calculate for how long to sleep or block, if at all	835	- Calculate for how long to sleep or block, if at all
758	(active idle watchers, EVLOOP_NONBLOCK or not having	836	(active idle watchers, EVRUN_NOWAIT or not having
759	any active watchers at all will result in not sleeping).	837	any active watchers at all will result in not sleeping).
760	- Sleep if the I/O and timer collect interval say so.	838	- Sleep if the I/O and timer collect interval say so.
		839	- Increment loop iteration counter.
761	- Block the process, waiting for any events.	840	- Block the process, waiting for any events.
762	- Queue all outstanding I/O (fd) events.	841	- Queue all outstanding I/O (fd) events.
763	- Update the "event loop time" (ev_now ()), and do time jump adjustments.	842	- Update the "event loop time" (ev_now ()), and do time jump adjustments.
764	- Queue all expired timers.	843	- Queue all expired timers.
765	- Queue all expired periodics.	844	- Queue all expired periodics.
766	- Unless any events are pending now, queue all idle watchers.	845	- Queue all idle watchers with priority higher than that of pending events.
767	- Queue all check watchers.	846	- Queue all check watchers.
768	- Call all queued watchers in reverse order (i.e. check watchers first).	847	- 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	848	Signals and child watchers are implemented as I/O watchers, and will
770	be handled here by queueing them when their watcher gets executed.	849	be handled here by queueing them when their watcher gets executed.
771	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	850	- If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT
772	were used, or there are no active watchers, return, otherwise	851	were used, or there are no active watchers, goto FINISH, otherwise
773	continue with step *.	852	continue with step LOOP.
		853	FINISH:
		854	- Reset the ev_break status iff it was EVBREAK_ONE.
		855	- Decrement the loop depth.
		856	- Return.
774		857
775	Example: Queue some jobs and then loop until no events are outstanding	858	Example: Queue some jobs and then loop until no events are outstanding
776	anymore.	859	anymore.
777		860
778	... queue jobs here, make sure they register event watchers as long	861	... 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..)	862	... as they still have work to do (even an idle watcher will do..)
780	ev_loop (my_loop, 0);	863	ev_run (my_loop, 0);
781	... jobs done or somebody called unloop. yeah!	864	... jobs done or somebody called unloop. yeah!
782		865
783	=item ev_unloop (loop, how)	866	=item ev_break (loop, how)
784		867
785	Can be used to make a call to C<ev_loop> return early (but only after it	868	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	869	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	870	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.	871	C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return.
789		872
790	This "unloop state" will be cleared when entering C<ev_loop> again.	873	This "break state" will be cleared on the next call to C<ev_run>.
791		874
792	It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls.	875	It is safe to call C<ev_break> from outside any C<ev_run> calls, too, in
		876	which case it will have no effect.
793		877
794	=item ev_ref (loop)	878	=item ev_ref (loop)
795		879
796	=item ev_unref (loop)	880	=item ev_unref (loop)
797		881
798	Ref/unref can be used to add or remove a reference count on the event	882	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	883	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.	884	count is nonzero, C<ev_run> will not return on its own.
801		885
802	This is useful when you have a watcher that you never intend to	886	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	887	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>	888	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>
805	before stopping it.	889	before stopping it.
806		890
807	As an example, libev itself uses this for its internal signal pipe: It	891	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	892	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	893	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	894	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	895	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	896	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	897	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>	898	(e.g. non-repeating timers) in which case you have to C<ev_ref>
815	in the callback).	899	in the callback).
816		900
817	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	901	Example: Create a signal watcher, but keep it from keeping C<ev_run>
818	running when nothing else is active.	902	running when nothing else is active.
819		903
820	ev_signal exitsig;	904	ev_signal exitsig;
821	ev_signal_init (&exitsig, sig_cb, SIGINT);	905	ev_signal_init (&exitsig, sig_cb, SIGINT);
822	ev_signal_start (loop, &exitsig);	906	ev_signal_start (loop, &exitsig);
823	evf_unref (loop);	907	ev_unref (loop);
824		908
825	Example: For some weird reason, unregister the above signal handler again.	909	Example: For some weird reason, unregister the above signal handler again.
826		910
827	ev_ref (loop);	911	ev_ref (loop);
828	ev_signal_stop (loop, &exitsig);	912	ev_signal_stop (loop, &exitsig);
…		…
867	usually doesn't make much sense to set it to a lower value than C<0.01>,	951	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	952	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	953	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	954	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,	955	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).	956	then you can't do more than 100 transactions per second).
873		957
874	Setting the I<timeout collect interval> can improve the opportunity for	958	Setting the I<timeout collect interval> can improve the opportunity for
875	saving power, as the program will "bundle" timer callback invocations that	959	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	960	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	961	times the process sleeps and wakes up again. Another useful technique to
…		…
885	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);	969	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);
886		970
887	=item ev_invoke_pending (loop)	971	=item ev_invoke_pending (loop)
888		972
889	This call will simply invoke all pending watchers while resetting their	973	This call will simply invoke all pending watchers while resetting their
890	pending state. Normally, C<ev_loop> does this automatically when required,	974	pending state. Normally, C<ev_run> does this automatically when required,
891	but when overriding the invoke callback this call comes handy.	975	but when overriding the invoke callback this call comes handy. This
		976	function can be invoked from a watcher - this can be useful for example
		977	when you want to do some lengthy calculation and want to pass further
		978	event handling to another thread (you still have to make sure only one
		979	thread executes within C<ev_invoke_pending> or C<ev_run> of course).
892		980
893	=item int ev_pending_count (loop)	981	=item int ev_pending_count (loop)
894		982
895	Returns the number of pending watchers - zero indicates that no watchers	983	Returns the number of pending watchers - zero indicates that no watchers
896	are pending.	984	are pending.
897		985
898	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))	986	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))
899		987
900	This overrides the invoke pending functionality of the loop: Instead of	988	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	989	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	990	this callback instead. This is useful, for example, when you want to
903	invoke the actual watchers inside another context (another thread etc.).	991	invoke the actual watchers inside another context (another thread etc.).
904		992
905	If you want to reset the callback, use C<ev_invoke_pending> as new	993	If you want to reset the callback, use C<ev_invoke_pending> as new
906	callback.	994	callback.
…		…
909		997
910	Sometimes you want to share the same loop between multiple threads. This	998	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	999	can be done relatively simply by putting mutex_lock/unlock calls around
912	each call to a libev function.	1000	each call to a libev function.
913		1001
914	However, C<ev_loop> can run an indefinite time, so it is not feasible to	1002	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	1003	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>	1004	loop via C<ev_break> and C<av_async_send>, another way is to set these
917	and I<acquire> callbacks on the loop.	1005	I<release> and I<acquire> callbacks on the loop.
918		1006
919	When set, then C<release> will be called just before the thread is	1007	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	1008	suspended waiting for new events, and C<acquire> is called just
921	afterwards.	1009	afterwards.
922		1010
…		…
925		1013
926	While event loop modifications are allowed between invocations of	1014	While event loop modifications are allowed between invocations of
927	C<release> and C<acquire> (that's their only purpose after all), no	1015	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	1016	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	1017	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	1018	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.	1019	to take note of any changes you made.
932		1020
933	In theory, threads executing C<ev_loop> will be async-cancel safe between	1021	In theory, threads executing C<ev_run> will be async-cancel safe between
934	invocations of C<release> and C<acquire>.	1022	invocations of C<release> and C<acquire>.
935		1023
936	See also the locking example in the C<THREADS> section later in this	1024	See also the locking example in the C<THREADS> section later in this
937	document.	1025	document.
938		1026
939	=item ev_set_userdata (loop, void *data)	1027	=item ev_set_userdata (loop, void *data)
940		1028
941	=item ev_userdata (loop)	1029	=item void *ev_userdata (loop)
942		1030
943	Set and retrieve a single C<void *> associated with a loop. When	1031	Set and retrieve a single C<void *> associated with a loop. When
944	C<ev_set_userdata> has never been called, then C<ev_userdata> returns	1032	C<ev_set_userdata> has never been called, then C<ev_userdata> returns
945	C<0.>	1033	C<0>.
946		1034
947	These two functions can be used to associate arbitrary data with a loop,	1035	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	1036	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	1037	C<acquire> callbacks described above, but of course can be (ab-)used for
950	any other purpose as well.	1038	any other purpose as well.
951		1039
952	=item ev_loop_verify (loop)	1040	=item ev_verify (loop)
953		1041
954	This function only does something when C<EV_VERIFY> support has been	1042	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	1043	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	1044	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	1045	is found to be inconsistent, it will print an error message to standard
…		…
968		1056
969	In the following description, uppercase C<TYPE> in names stands for the	1057	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	1058	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.	1059	watchers and C<ev_io_start> for I/O watchers.
972		1060
973	A watcher is a structure that you create and register to record your	1061	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	1062	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:	1063	to wait for STDIN to become readable, you would create an C<ev_io> watcher
		1064	for that:
976		1065
977	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)	1066	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)
978	{	1067	{
979	ev_io_stop (w);	1068	ev_io_stop (w);
980	ev_unloop (loop, EVUNLOOP_ALL);	1069	ev_break (loop, EVBREAK_ALL);
981	}	1070	}
982		1071
983	struct ev_loop *loop = ev_default_loop (0);	1072	struct ev_loop *loop = ev_default_loop (0);
984		1073
985	ev_io stdin_watcher;	1074	ev_io stdin_watcher;
986		1075
987	ev_init (&stdin_watcher, my_cb);	1076	ev_init (&stdin_watcher, my_cb);
988	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	1077	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
989	ev_io_start (loop, &stdin_watcher);	1078	ev_io_start (loop, &stdin_watcher);
990		1079
991	ev_loop (loop, 0);	1080	ev_run (loop, 0);
992		1081
993	As you can see, you are responsible for allocating the memory for your	1082	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	1083	watcher structures (and it is I<usually> a bad idea to do this on the
995	stack).	1084	stack).
996		1085
997	Each watcher has an associated watcher structure (called C<struct ev_TYPE>	1086	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).	1087	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).
999		1088
1000	Each watcher structure must be initialised by a call to C<ev_init	1089	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	1090	*, 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	1091	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	1092	time the event loop detects that the file descriptor given is readable
1004	is readable and/or writable).	1093	and/or writable).
1005		1094
1006	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>	1095	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	1096	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<<	1097	is also a macro to combine initialisation and setting in one call: C<<
1009	ev_TYPE_init (watcher *, callback, ...) >>.	1098	ev_TYPE_init (watcher *, callback, ...) >>.
…		…
1032	=item C<EV_WRITE>	1121	=item C<EV_WRITE>
1033		1122
1034	The file descriptor in the C<ev_io> watcher has become readable and/or	1123	The file descriptor in the C<ev_io> watcher has become readable and/or
1035	writable.	1124	writable.
1036		1125
1037	=item C<EV_TIMEOUT>	1126	=item C<EV_TIMER>
1038		1127
1039	The C<ev_timer> watcher has timed out.	1128	The C<ev_timer> watcher has timed out.
1040		1129
1041	=item C<EV_PERIODIC>	1130	=item C<EV_PERIODIC>
1042		1131
…		…
1060		1149
1061	=item C<EV_PREPARE>	1150	=item C<EV_PREPARE>
1062		1151
1063	=item C<EV_CHECK>	1152	=item C<EV_CHECK>
1064		1153
1065	All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts	1154	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	1155	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	1156	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	1157	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	1158	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	1159	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
1071	C<ev_loop> from blocking).	1160	C<ev_run> from blocking).
1072		1161
1073	=item C<EV_EMBED>	1162	=item C<EV_EMBED>
1074		1163
1075	The embedded event loop specified in the C<ev_embed> watcher needs attention.	1164	The embedded event loop specified in the C<ev_embed> watcher needs attention.
1076		1165
1077	=item C<EV_FORK>	1166	=item C<EV_FORK>
1078		1167
1079	The event loop has been resumed in the child process after fork (see	1168	The event loop has been resumed in the child process after fork (see
1080	C<ev_fork>).	1169	C<ev_fork>).
		1170
		1171	=item C<EV_CLEANUP>
		1172
		1173	The event loop is about to be destroyed (see C<ev_cleanup>).
1081		1174
1082	=item C<EV_ASYNC>	1175	=item C<EV_ASYNC>
1083		1176
1084	The given async watcher has been asynchronously notified (see C<ev_async>).	1177	The given async watcher has been asynchronously notified (see C<ev_async>).
1085		1178
…		…
1257		1350
1258	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related	1351	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related
1259	functions that do not need a watcher.	1352	functions that do not need a watcher.
1260		1353
1261	=back	1354	=back
1262
1263		1355
1264	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	1356	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
1265		1357
1266	Each watcher has, by default, a member C<void *data> that you can change	1358	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	1359	and read at any time: libev will completely ignore it. This can be used
…		…
1323	t2_cb (EV_P_ ev_timer *w, int revents)	1415	t2_cb (EV_P_ ev_timer *w, int revents)
1324	{	1416	{
1325	struct my_biggy big = (struct my_biggy *)	1417	struct my_biggy big = (struct my_biggy *)
1326	(((char *)w) - offsetof (struct my_biggy, t2));	1418	(((char *)w) - offsetof (struct my_biggy, t2));
1327	}	1419	}
		1420
		1421	=head2 WATCHER STATES
		1422
		1423	There are various watcher states mentioned throughout this manual -
		1424	active, pending and so on. In this section these states and the rules to
		1425	transition between them will be described in more detail - and while these
		1426	rules might look complicated, they usually do "the right thing".
		1427
		1428	=over 4
		1429
		1430	=item initialiased
		1431
		1432	Before a watcher can be registered with the event looop it has to be
		1433	initialised. This can be done with a call to C<ev_TYPE_init>, or calls to
		1434	C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function.
		1435
		1436	In this state it is simply some block of memory that is suitable for use
		1437	in an event loop. It can be moved around, freed, reused etc. at will.
		1438
		1439	=item started/running/active
		1440
		1441	Once a watcher has been started with a call to C<ev_TYPE_start> it becomes
		1442	property of the event loop, and is actively waiting for events. While in
		1443	this state it cannot be accessed (except in a few documented ways), moved,
		1444	freed or anything else - the only legal thing is to keep a pointer to it,
		1445	and call libev functions on it that are documented to work on active watchers.
		1446
		1447	=item pending
		1448
		1449	If a watcher is active and libev determines that an event it is interested
		1450	in has occurred (such as a timer expiring), it will become pending. It will
		1451	stay in this pending state until either it is stopped or its callback is
		1452	about to be invoked, so it is not normally pending inside the watcher
		1453	callback.
		1454
		1455	The watcher might or might not be active while it is pending (for example,
		1456	an expired non-repeating timer can be pending but no longer active). If it
		1457	is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>),
		1458	but it is still property of the event loop at this time, so cannot be
		1459	moved, freed or reused. And if it is active the rules described in the
		1460	previous item still apply.
		1461
		1462	It is also possible to feed an event on a watcher that is not active (e.g.
		1463	via C<ev_feed_event>), in which case it becomes pending without being
		1464	active.
		1465
		1466	=item stopped
		1467
		1468	A watcher can be stopped implicitly by libev (in which case it might still
		1469	be pending), or explicitly by calling its C<ev_TYPE_stop> function. The
		1470	latter will clear any pending state the watcher might be in, regardless
		1471	of whether it was active or not, so stopping a watcher explicitly before
		1472	freeing it is often a good idea.
		1473
		1474	While stopped (and not pending) the watcher is essentially in the
		1475	initialised state, that is it can be reused, moved, modified in any way
		1476	you wish.
		1477
		1478	=back
1328		1479
1329	=head2 WATCHER PRIORITY MODELS	1480	=head2 WATCHER PRIORITY MODELS
1330		1481
1331	Many event loops support I<watcher priorities>, which are usually small	1482	Many event loops support I<watcher priorities>, which are usually small
1332	integers that influence the ordering of event callback invocation	1483	integers that influence the ordering of event callback invocation
…		…
1375		1526
1376	For example, to emulate how many other event libraries handle priorities,	1527	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	1528	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	1529	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	1530	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	1531	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	1532	the lock-out case is known to be rare (which in turn is rare :), this is
1382	workable.	1533	workable.
1383		1534
1384	Usually, however, the lock-out model implemented that way will perform	1535	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,	1536	miserably under the type of load it was designed to handle. In that case,
…		…
1399	{	1550	{
1400	// stop the I/O watcher, we received the event, but	1551	// stop the I/O watcher, we received the event, but
1401	// are not yet ready to handle it.	1552	// are not yet ready to handle it.
1402	ev_io_stop (EV_A_ w);	1553	ev_io_stop (EV_A_ w);
1403		1554
1404	// start the idle watcher to ahndle the actual event.	1555	// start the idle watcher to handle the actual event.
1405	// it will not be executed as long as other watchers	1556	// it will not be executed as long as other watchers
1406	// with the default priority are receiving events.	1557	// with the default priority are receiving events.
1407	ev_idle_start (EV_A_ &idle);	1558	ev_idle_start (EV_A_ &idle);
1408	}	1559	}
1409		1560
…		…
1463		1614
1464	If you cannot use non-blocking mode, then force the use of a	1615	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	1616	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	1617	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file
1467	descriptors for which non-blocking operation makes no sense (such as	1618	descriptors for which non-blocking operation makes no sense (such as
1468	files) - libev doesn't guarentee any specific behaviour in that case.	1619	files) - libev doesn't guarantee any specific behaviour in that case.
1469		1620
1470	Another thing you have to watch out for is that it is quite easy to	1621	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	1622	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	1623	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	1624	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).	1692	somewhere, as that would have given you a big clue).
1542		1693
1543	=head3 The special problem of accept()ing when you can't	1694	=head3 The special problem of accept()ing when you can't
1544		1695
1545	Many implementations of the POSIX C<accept> function (for example,	1696	Many implementations of the POSIX C<accept> function (for example,
1546	found in port-2004 Linux) have the peculiar behaviour of not removing a	1697	found in post-2004 Linux) have the peculiar behaviour of not removing a
1547	connection from the pending queue in all error cases.	1698	connection from the pending queue in all error cases.
1548		1699
1549	For example, larger servers often run out of file descriptors (because	1700	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	1701	of resource limits), causing C<accept> to fail with C<ENFILE> but not
1551	rejecting the connection, leading to libev signalling readiness on	1702	rejecting the connection, leading to libev signalling readiness on
…		…
1617	...	1768	...
1618	struct ev_loop *loop = ev_default_init (0);	1769	struct ev_loop *loop = ev_default_init (0);
1619	ev_io stdin_readable;	1770	ev_io stdin_readable;
1620	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1771	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1621	ev_io_start (loop, &stdin_readable);	1772	ev_io_start (loop, &stdin_readable);
1622	ev_loop (loop, 0);	1773	ev_run (loop, 0);
1623		1774
1624		1775
1625	=head2 C<ev_timer> - relative and optionally repeating timeouts	1776	=head2 C<ev_timer> - relative and optionally repeating timeouts
1626		1777
1627	Timer watchers are simple relative timers that generate an event after a	1778	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	1787	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	1788	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	1789	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	1790	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	1791	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).	1792	no longer true when a callback calls C<ev_run> recursively).
1642		1793
1643	=head3 Be smart about timeouts	1794	=head3 Be smart about timeouts
1644		1795
1645	Many real-world problems involve some kind of timeout, usually for error	1796	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,	1797	recovery. A typical example is an HTTP request - if the other side hangs,
…		…
1732	ev_tstamp timeout = last_activity + 60.;	1883	ev_tstamp timeout = last_activity + 60.;
1733		1884
1734	// if last_activity + 60. is older than now, we did time out	1885	// if last_activity + 60. is older than now, we did time out
1735	if (timeout < now)	1886	if (timeout < now)
1736	{	1887	{
1737	// timeout occured, take action	1888	// timeout occurred, take action
1738	}	1889	}
1739	else	1890	else
1740	{	1891	{
1741	// callback was invoked, but there was some activity, re-arm	1892	// callback was invoked, but there was some activity, re-arm
1742	// the watcher to fire in last_activity + 60, which is	1893	// the watcher to fire in last_activity + 60, which is
…		…
1764	to the current time (meaning we just have some activity :), then call the	1915	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:	1916	callback, which will "do the right thing" and start the timer:
1766		1917
1767	ev_init (timer, callback);	1918	ev_init (timer, callback);
1768	last_activity = ev_now (loop);	1919	last_activity = ev_now (loop);
1769	callback (loop, timer, EV_TIMEOUT);	1920	callback (loop, timer, EV_TIMER);
1770		1921
1771	And when there is some activity, simply store the current time in	1922	And when there is some activity, simply store the current time in
1772	C<last_activity>, no libev calls at all:	1923	C<last_activity>, no libev calls at all:
1773		1924
1774	last_actiivty = ev_now (loop);	1925	last_activity = ev_now (loop);
1775		1926
1776	This technique is slightly more complex, but in most cases where the	1927	This technique is slightly more complex, but in most cases where the
1777	time-out is unlikely to be triggered, much more efficient.	1928	time-out is unlikely to be triggered, much more efficient.
1778		1929
1779	Changing the timeout is trivial as well (if it isn't hard-coded in the	1930	Changing the timeout is trivial as well (if it isn't hard-coded in the
…		…
1817		1968
1818	=head3 The special problem of time updates	1969	=head3 The special problem of time updates
1819		1970
1820	Establishing the current time is a costly operation (it usually takes at	1971	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	1972	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	1973	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	1974	growing difference between C<ev_now ()> and C<ev_time ()> when handling
1824	lots of events in one iteration.	1975	lots of events in one iteration.
1825		1976
1826	The relative timeouts are calculated relative to the C<ev_now ()>	1977	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	1978	time. This is usually the right thing as this timestamp refers to the time
…		…
1944	}	2095	}
1945		2096
1946	ev_timer mytimer;	2097	ev_timer mytimer;
1947	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	2098	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1948	ev_timer_again (&mytimer); /* start timer */	2099	ev_timer_again (&mytimer); /* start timer */
1949	ev_loop (loop, 0);	2100	ev_run (loop, 0);
1950		2101
1951	// and in some piece of code that gets executed on any "activity":	2102	// and in some piece of code that gets executed on any "activity":
1952	// reset the timeout to start ticking again at 10 seconds	2103	// reset the timeout to start ticking again at 10 seconds
1953	ev_timer_again (&mytimer);	2104	ev_timer_again (&mytimer);
1954		2105
…		…
1980		2131
1981	As with timers, the callback is guaranteed to be invoked only when the	2132	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	2133	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	2134	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	2135	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).	2136	(but this is no longer true when a callback calls C<ev_run> recursively).
1986		2137
1987	=head3 Watcher-Specific Functions and Data Members	2138	=head3 Watcher-Specific Functions and Data Members
1988		2139
1989	=over 4	2140	=over 4
1990		2141
…		…
2118	Example: Call a callback every hour, or, more precisely, whenever the	2269	Example: Call a callback every hour, or, more precisely, whenever the
2119	system time is divisible by 3600. The callback invocation times have	2270	system time is divisible by 3600. The callback invocation times have
2120	potentially a lot of jitter, but good long-term stability.	2271	potentially a lot of jitter, but good long-term stability.
2121		2272
2122	static void	2273	static void
2123	clock_cb (struct ev_loop *loop, ev_io *w, int revents)	2274	clock_cb (struct ev_loop *loop, ev_periodic *w, int revents)
2124	{	2275	{
2125	... its now a full hour (UTC, or TAI or whatever your clock follows)	2276	... its now a full hour (UTC, or TAI or whatever your clock follows)
2126	}	2277	}
2127		2278
2128	ev_periodic hourly_tick;	2279	ev_periodic hourly_tick;
…		…
2151		2302
2152	=head2 C<ev_signal> - signal me when a signal gets signalled!	2303	=head2 C<ev_signal> - signal me when a signal gets signalled!
2153		2304
2154	Signal watchers will trigger an event when the process receives a specific	2305	Signal watchers will trigger an event when the process receives a specific
2155	signal one or more times. Even though signals are very asynchronous, libev	2306	signal one or more times. Even though signals are very asynchronous, libev
2156	will try it's best to deliver signals synchronously, i.e. as part of the	2307	will try its best to deliver signals synchronously, i.e. as part of the
2157	normal event processing, like any other event.	2308	normal event processing, like any other event.
2158		2309
2159	If you want signals to be delivered truly asynchronously, just use	2310	If you want signals to be delivered truly asynchronously, just use
2160	C<sigaction> as you would do without libev and forget about sharing	2311	C<sigaction> as you would do without libev and forget about sharing
2161	the signal. You can even use C<ev_async> from a signal handler to	2312	the signal. You can even use C<ev_async> from a signal handler to
…		…
2204		2355
2205	So I can't stress this enough: I<If you do not reset your signal mask when	2356	So I can't stress this enough: I<If you do not reset your signal mask when
2206	you expect it to be empty, you have a race condition in your code>. This	2357	you expect it to be empty, you have a race condition in your code>. This
2207	is not a libev-specific thing, this is true for most event libraries.	2358	is not a libev-specific thing, this is true for most event libraries.
2208		2359
		2360	=head3 The special problem of threads signal handling
		2361
		2362	POSIX threads has problematic signal handling semantics, specifically,
		2363	a lot of functionality (sigfd, sigwait etc.) only really works if all
		2364	threads in a process block signals, which is hard to achieve.
		2365
		2366	When you want to use sigwait (or mix libev signal handling with your own
		2367	for the same signals), you can tackle this problem by globally blocking
		2368	all signals before creating any threads (or creating them with a fully set
		2369	sigprocmask) and also specifying the C<EVFLAG_NOSIGMASK> when creating
		2370	loops. Then designate one thread as "signal receiver thread" which handles
		2371	these signals. You can pass on any signals that libev might be interested
		2372	in by calling C<ev_feed_signal>.
		2373
2209	=head3 Watcher-Specific Functions and Data Members	2374	=head3 Watcher-Specific Functions and Data Members
2210		2375
2211	=over 4	2376	=over 4
2212		2377
2213	=item ev_signal_init (ev_signal *, callback, int signum)	2378	=item ev_signal_init (ev_signal *, callback, int signum)
…		…
2228	Example: Try to exit cleanly on SIGINT.	2393	Example: Try to exit cleanly on SIGINT.
2229		2394
2230	static void	2395	static void
2231	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)	2396	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)
2232	{	2397	{
2233	ev_unloop (loop, EVUNLOOP_ALL);	2398	ev_break (loop, EVBREAK_ALL);
2234	}	2399	}
2235		2400
2236	ev_signal signal_watcher;	2401	ev_signal signal_watcher;
2237	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	2402	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
2238	ev_signal_start (loop, &signal_watcher);	2403	ev_signal_start (loop, &signal_watcher);
…		…
2624		2789
2625	Prepare and check watchers are usually (but not always) used in pairs:	2790	Prepare and check watchers are usually (but not always) used in pairs:
2626	prepare watchers get invoked before the process blocks and check watchers	2791	prepare watchers get invoked before the process blocks and check watchers
2627	afterwards.	2792	afterwards.
2628		2793
2629	You I<must not> call C<ev_loop> or similar functions that enter	2794	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>	2795	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	2796	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	2797	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,	2798	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	2799	C<ev_check> so if you have one watcher of each kind they will always be
…		…
2802		2967
2803	if (timeout >= 0)	2968	if (timeout >= 0)
2804	// create/start timer	2969	// create/start timer
2805		2970
2806	// poll	2971	// poll
2807	ev_loop (EV_A_ 0);	2972	ev_run (EV_A_ 0);
2808		2973
2809	// stop timer again	2974	// stop timer again
2810	if (timeout >= 0)	2975	if (timeout >= 0)
2811	ev_timer_stop (EV_A_ &to);	2976	ev_timer_stop (EV_A_ &to);
2812		2977
…		…
2890	if you do not want that, you need to temporarily stop the embed watcher).	3055	if you do not want that, you need to temporarily stop the embed watcher).
2891		3056
2892	=item ev_embed_sweep (loop, ev_embed *)	3057	=item ev_embed_sweep (loop, ev_embed *)
2893		3058
2894	Make a single, non-blocking sweep over the embedded loop. This works	3059	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	3060	similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most
2896	appropriate way for embedded loops.	3061	appropriate way for embedded loops.
2897		3062
2898	=item struct ev_loop *other [read-only]	3063	=item struct ev_loop *other [read-only]
2899		3064
2900	The embedded event loop.	3065	The embedded event loop.
…		…
2960	C<ev_default_fork> cheats and calls it in the wrong process, the fork	3125	C<ev_default_fork> cheats and calls it in the wrong process, the fork
2961	handlers will be invoked, too, of course.	3126	handlers will be invoked, too, of course.
2962		3127
2963	=head3 The special problem of life after fork - how is it possible?	3128	=head3 The special problem of life after fork - how is it possible?
2964		3129
2965	Most uses of C<fork()> consist of forking, then some simple calls to ste	3130	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	3131	up/change the process environment, followed by a call to C<exec()>. This
2967	sequence should be handled by libev without any problems.	3132	sequence should be handled by libev without any problems.
2968		3133
2969	This changes when the application actually wants to do event handling	3134	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	3135	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	3151	disadvantage of having to use multiple event loops (which do not support
2987	signal watchers).	3152	signal watchers).
2988		3153
2989	When this is not possible, or you want to use the default loop for	3154	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	3155	other reasons, then in the process that wants to start "fresh", call
2991	C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying	3156	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	3157	Destroying the default loop will "orphan" (not stop) all registered
2993	have to be careful not to execute code that modifies those watchers. Note	3158	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.	3159	those watchers. Note also that in that case, you have to re-register any
		3160	signal watchers.
2995		3161
2996	=head3 Watcher-Specific Functions and Data Members	3162	=head3 Watcher-Specific Functions and Data Members
2997		3163
2998	=over 4	3164	=over 4
2999		3165
3000	=item ev_fork_init (ev_signal *, callback)	3166	=item ev_fork_init (ev_fork *, callback)
3001		3167
3002	Initialises and configures the fork watcher - it has no parameters of any	3168	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,	3169	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
3004	believe me.	3170	really.
3005		3171
3006	=back	3172	=back
3007		3173
3008		3174
		3175	=head2 C<ev_cleanup> - even the best things end
		3176
		3177	Cleanup watchers are called just before the event loop is being destroyed
		3178	by a call to C<ev_loop_destroy>.
		3179
		3180	While there is no guarantee that the event loop gets destroyed, cleanup
		3181	watchers provide a convenient method to install cleanup hooks for your
		3182	program, worker threads and so on - you just to make sure to destroy the
		3183	loop when you want them to be invoked.
		3184
		3185	Cleanup watchers are invoked in the same way as any other watcher. Unlike
		3186	all other watchers, they do not keep a reference to the event loop (which
		3187	makes a lot of sense if you think about it). Like all other watchers, you
		3188	can call libev functions in the callback, except C<ev_cleanup_start>.
		3189
		3190	=head3 Watcher-Specific Functions and Data Members
		3191
		3192	=over 4
		3193
		3194	=item ev_cleanup_init (ev_cleanup *, callback)
		3195
		3196	Initialises and configures the cleanup watcher - it has no parameters of
		3197	any kind. There is a C<ev_cleanup_set> macro, but using it is utterly
		3198	pointless, I assure you.
		3199
		3200	=back
		3201
		3202	Example: Register an atexit handler to destroy the default loop, so any
		3203	cleanup functions are called.
		3204
		3205	static void
		3206	program_exits (void)
		3207	{
		3208	ev_loop_destroy (EV_DEFAULT_UC);
		3209	}
		3210
		3211	...
		3212	atexit (program_exits);
		3213
		3214
3009	=head2 C<ev_async> - how to wake up another event loop	3215	=head2 C<ev_async> - how to wake up an event loop
3010		3216
3011	In general, you cannot use an C<ev_loop> from multiple threads or other	3217	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	3218	asynchronous sources such as signal handlers (as opposed to multiple event
3013	loops - those are of course safe to use in different threads).	3219	loops - those are of course safe to use in different threads).
3014		3220
3015	Sometimes, however, you need to wake up another event loop you do not	3221	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	3222	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	3223	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	3224	it by calling C<ev_async_send>, which is thread- and signal safe.
3019	safe.
3020		3225
3021	This functionality is very similar to C<ev_signal> watchers, as signals,	3226	This functionality is very similar to C<ev_signal> watchers, as signals,
3022	too, are asynchronous in nature, and signals, too, will be compressed	3227	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	3228	(i.e. the number of callback invocations may be less than the number of
3024	C<ev_async_sent> calls).	3229	C<ev_async_sent> calls). In fact, you could use signal watchers as a kind
		3230	of "global async watchers" by using a watcher on an otherwise unused
		3231	signal, and C<ev_feed_signal> to signal this watcher from another thread,
		3232	even without knowing which loop owns the signal.
3025		3233
3026	Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not	3234	Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not
3027	just the default loop.	3235	just the default loop.
3028		3236
3029	=head3 Queueing	3237	=head3 Queueing
…		…
3179		3387
3180	If C<timeout> is less than 0, then no timeout watcher will be	3388	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	3389	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and
3182	repeat = 0) will be started. C<0> is a valid timeout.	3390	repeat = 0) will be started. C<0> is a valid timeout.
3183		3391
3184	The callback has the type C<void (*cb)(int revents, void *arg)> and gets	3392	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	3393	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>	3394	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>	3395	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	3396	a timeout and an io event at the same time - you probably should give io
3189	events precedence.	3397	events precedence.
3190		3398
3191	Example: wait up to ten seconds for data to appear on STDIN_FILENO.	3399	Example: wait up to ten seconds for data to appear on STDIN_FILENO.
3192		3400
3193	static void stdin_ready (int revents, void *arg)	3401	static void stdin_ready (int revents, void *arg)
3194	{	3402	{
3195	if (revents & EV_READ)	3403	if (revents & EV_READ)
3196	/* stdin might have data for us, joy! */;	3404	/* stdin might have data for us, joy! */;
3197	else if (revents & EV_TIMEOUT)	3405	else if (revents & EV_TIMER)
3198	/* doh, nothing entered */;	3406	/* doh, nothing entered */;
3199	}	3407	}
3200		3408
3201	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	3409	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
3202		3410
…		…
3205	Feed an event on the given fd, as if a file descriptor backend detected	3413	Feed an event on the given fd, as if a file descriptor backend detected
3206	the given events it.	3414	the given events it.
3207		3415
3208	=item ev_feed_signal_event (loop, int signum)	3416	=item ev_feed_signal_event (loop, int signum)
3209		3417
3210	Feed an event as if the given signal occurred (C<loop> must be the default	3418	Feed an event as if the given signal occurred. See also C<ev_feed_signal>,
3211	loop!).	3419	which is async-safe.
		3420
		3421	=back
		3422
		3423
		3424	=head1 COMMON OR USEFUL IDIOMS (OR BOTH)
		3425
		3426	This section explains some common idioms that are not immediately
		3427	obvious. Note that examples are sprinkled over the whole manual, and this
		3428	section only contains stuff that wouldn't fit anywhere else.
		3429
		3430	=over 4
		3431
		3432	=item Model/nested event loop invocations and exit conditions.
		3433
		3434	Often (especially in GUI toolkits) there are places where you have
		3435	I<modal> interaction, which is most easily implemented by recursively
		3436	invoking C<ev_run>.
		3437
		3438	This brings the problem of exiting - a callback might want to finish the
		3439	main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but
		3440	a modal "Are you sure?" dialog is still waiting), or just the nested one
		3441	and not the main one (e.g. user clocked "Ok" in a modal dialog), or some
		3442	other combination: In these cases, C<ev_break> will not work alone.
		3443
		3444	The solution is to maintain "break this loop" variable for each C<ev_run>
		3445	invocation, and use a loop around C<ev_run> until the condition is
		3446	triggered, using C<EVRUN_ONCE>:
		3447
		3448	// main loop
		3449	int exit_main_loop = 0;
		3450
		3451	while (!exit_main_loop)
		3452	ev_run (EV_DEFAULT_ EVRUN_ONCE);
		3453
		3454	// in a model watcher
		3455	int exit_nested_loop = 0;
		3456
		3457	while (!exit_nested_loop)
		3458	ev_run (EV_A_ EVRUN_ONCE);
		3459
		3460	To exit from any of these loops, just set the corresponding exit variable:
		3461
		3462	// exit modal loop
		3463	exit_nested_loop = 1;
		3464
		3465	// exit main program, after modal loop is finished
		3466	exit_main_loop = 1;
		3467
		3468	// exit both
		3469	exit_main_loop = exit_nested_loop = 1;
3212		3470
3213	=back	3471	=back
3214		3472
3215		3473
3216	=head1 LIBEVENT EMULATION	3474	=head1 LIBEVENT EMULATION
3217		3475
3218	Libev offers a compatibility emulation layer for libevent. It cannot	3476	Libev offers a compatibility emulation layer for libevent. It cannot
3219	emulate the internals of libevent, so here are some usage hints:	3477	emulate the internals of libevent, so here are some usage hints:
3220		3478
3221	=over 4	3479	=over 4
		3480
		3481	=item * Only the libevent-1.4.1-beta API is being emulated.
		3482
		3483	This was the newest libevent version available when libev was implemented,
		3484	and is still mostly unchanged in 2010.
3222		3485
3223	=item * Use it by including <event.h>, as usual.	3486	=item * Use it by including <event.h>, as usual.
3224		3487
3225	=item * The following members are fully supported: ev_base, ev_callback,	3488	=item * The following members are fully supported: ev_base, ev_callback,
3226	ev_arg, ev_fd, ev_res, ev_events.	3489	ev_arg, ev_fd, ev_res, ev_events.
…		…
3232	=item * Priorities are not currently supported. Initialising priorities	3495	=item * Priorities are not currently supported. Initialising priorities
3233	will fail and all watchers will have the same priority, even though there	3496	will fail and all watchers will have the same priority, even though there
3234	is an ev_pri field.	3497	is an ev_pri field.
3235		3498
3236	=item * In libevent, the last base created gets the signals, in libev, the	3499	=item * In libevent, the last base created gets the signals, in libev, the
3237	first base created (== the default loop) gets the signals.	3500	base that registered the signal gets the signals.
3238		3501
3239	=item * Other members are not supported.	3502	=item * Other members are not supported.
3240		3503
3241	=item * The libev emulation is I<not> ABI compatible to libevent, you need	3504	=item * The libev emulation is I<not> ABI compatible to libevent, you need
3242	to use the libev header file and library.	3505	to use the libev header file and library.
…		…
3261	Care has been taken to keep the overhead low. The only data member the C++	3524	Care has been taken to keep the overhead low. The only data member the C++
3262	classes add (compared to plain C-style watchers) is the event loop pointer	3525	classes add (compared to plain C-style watchers) is the event loop pointer
3263	that the watcher is associated with (or no additional members at all if	3526	that the watcher is associated with (or no additional members at all if
3264	you disable C<EV_MULTIPLICITY> when embedding libev).	3527	you disable C<EV_MULTIPLICITY> when embedding libev).
3265		3528
3266	Currently, functions, and static and non-static member functions can be	3529	Currently, functions, static and non-static member functions and classes
3267	used as callbacks. Other types should be easy to add as long as they only	3530	with C<operator ()> can be used as callbacks. Other types should be easy
3268	need one additional pointer for context. If you need support for other	3531	to add as long as they only need one additional pointer for context. If
3269	types of functors please contact the author (preferably after implementing	3532	you need support for other types of functors please contact the author
3270	it).	3533	(preferably after implementing it).
3271		3534
3272	Here is a list of things available in the C<ev> namespace:	3535	Here is a list of things available in the C<ev> namespace:
3273		3536
3274	=over 4	3537	=over 4
3275		3538
…		…
3336	myclass obj;	3599	myclass obj;
3337	ev::io iow;	3600	ev::io iow;
3338	iow.set <myclass, &myclass::io_cb> (&obj);	3601	iow.set <myclass, &myclass::io_cb> (&obj);
3339		3602
3340	=item w->set (object *)	3603	=item w->set (object *)
3341
3342	This is an B<experimental> feature that might go away in a future version.
3343		3604
3344	This is a variation of a method callback - leaving out the method to call	3605	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	3606	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	3607	functor objects without having to manually specify the C<operator ()> all
3347	the time. Incidentally, you can then also leave out the template argument	3608	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	3648	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).	3649	do this when the watcher is inactive (and not pending either).
3389		3650
3390	=item w->set ([arguments])	3651	=item w->set ([arguments])
3391		3652
3392	Basically the same as C<ev_TYPE_set>, with the same arguments. Must be	3653	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	3654	method or a suitable start method must be called at least once. Unlike the
3394	automatically stopped and restarted when reconfiguring it with this	3655	C counterpart, an active watcher gets automatically stopped and restarted
3395	method.	3656	when reconfiguring it with this method.
3396		3657
3397	=item w->start ()	3658	=item w->start ()
3398		3659
3399	Starts the watcher. Note that there is no C<loop> argument, as the	3660	Starts the watcher. Note that there is no C<loop> argument, as the
3400	constructor already stores the event loop.	3661	constructor already stores the event loop.
3401		3662
		3663	=item w->start ([arguments])
		3664
		3665	Instead of calling C<set> and C<start> methods separately, it is often
		3666	convenient to wrap them in one call. Uses the same type of arguments as
		3667	the configure C<set> method of the watcher.
		3668
3402	=item w->stop ()	3669	=item w->stop ()
3403		3670
3404	Stops the watcher if it is active. Again, no C<loop> argument.	3671	Stops the watcher if it is active. Again, no C<loop> argument.
3405		3672
3406	=item w->again () (C<ev::timer>, C<ev::periodic> only)	3673	=item w->again () (C<ev::timer>, C<ev::periodic> only)
…		…
3418		3685
3419	=back	3686	=back
3420		3687
3421	=back	3688	=back
3422		3689
3423	Example: Define a class with an IO and idle watcher, start one of them in	3690	Example: Define a class with two I/O and idle watchers, start the I/O
3424	the constructor.	3691	watchers in the constructor.
3425		3692
3426	class myclass	3693	class myclass
3427	{	3694	{
3428	ev::io io ; void io_cb (ev::io &w, int revents);	3695	ev::io io ; void io_cb (ev::io &w, int revents);
		3696	ev::io2 io2 ; void io2_cb (ev::io &w, int revents);
3429	ev::idle idle; void idle_cb (ev::idle &w, int revents);	3697	ev::idle idle; void idle_cb (ev::idle &w, int revents);
3430		3698
3431	myclass (int fd)	3699	myclass (int fd)
3432	{	3700	{
3433	io .set <myclass, &myclass::io_cb > (this);	3701	io .set <myclass, &myclass::io_cb > (this);
		3702	io2 .set <myclass, &myclass::io2_cb > (this);
3434	idle.set <myclass, &myclass::idle_cb> (this);	3703	idle.set <myclass, &myclass::idle_cb> (this);
3435		3704
3436	io.start (fd, ev::READ);	3705	io.set (fd, ev::WRITE); // configure the watcher
		3706	io.start (); // start it whenever convenient
		3707
		3708	io2.start (fd, ev::READ); // set + start in one call
3437	}	3709	}
3438	};	3710	};
3439		3711
3440		3712
3441	=head1 OTHER LANGUAGE BINDINGS	3713	=head1 OTHER LANGUAGE BINDINGS
…		…
3515	loop argument"). The C<EV_A> form is used when this is the sole argument,	3787	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:	3788	C<EV_A_> is used when other arguments are following. Example:
3517		3789
3518	ev_unref (EV_A);	3790	ev_unref (EV_A);
3519	ev_timer_add (EV_A_ watcher);	3791	ev_timer_add (EV_A_ watcher);
3520	ev_loop (EV_A_ 0);	3792	ev_run (EV_A_ 0);
3521		3793
3522	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	3794	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
3523	which is often provided by the following macro.	3795	which is often provided by the following macro.
3524		3796
3525	=item C<EV_P>, C<EV_P_>	3797	=item C<EV_P>, C<EV_P_>
…		…
3565	}	3837	}
3566		3838
3567	ev_check check;	3839	ev_check check;
3568	ev_check_init (&check, check_cb);	3840	ev_check_init (&check, check_cb);
3569	ev_check_start (EV_DEFAULT_ &check);	3841	ev_check_start (EV_DEFAULT_ &check);
3570	ev_loop (EV_DEFAULT_ 0);	3842	ev_run (EV_DEFAULT_ 0);
3571		3843
3572	=head1 EMBEDDING	3844	=head1 EMBEDDING
3573		3845
3574	Libev can (and often is) directly embedded into host	3846	Libev can (and often is) directly embedded into host
3575	applications. Examples of applications that embed it include the Deliantra	3847	applications. Examples of applications that embed it include the Deliantra
…		…
3660	define before including (or compiling) any of its files. The default in	3932	define before including (or compiling) any of its files. The default in
3661	the absence of autoconf is documented for every option.	3933	the absence of autoconf is documented for every option.
3662		3934
3663	Symbols marked with "(h)" do not change the ABI, and can have different	3935	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	3936	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	3937	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	3938	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	3939	users of libev and the libev code itself must be compiled with compatible
3668	settings.	3940	settings.
3669		3941
3670	=over 4	3942	=over 4
		3943
		3944	=item EV_COMPAT3 (h)
		3945
		3946	Backwards compatibility is a major concern for libev. This is why this
		3947	release of libev comes with wrappers for the functions and symbols that
		3948	have been renamed between libev version 3 and 4.
		3949
		3950	You can disable these wrappers (to test compatibility with future
		3951	versions) by defining C<EV_COMPAT3> to C<0> when compiling your
		3952	sources. This has the additional advantage that you can drop the C<struct>
		3953	from C<struct ev_loop> declarations, as libev will provide an C<ev_loop>
		3954	typedef in that case.
		3955
		3956	In some future version, the default for C<EV_COMPAT3> will become C<0>,
		3957	and in some even more future version the compatibility code will be
		3958	removed completely.
3671		3959
3672	=item EV_STANDALONE (h)	3960	=item EV_STANDALONE (h)
3673		3961
3674	Must always be C<1> if you do not use autoconf configuration, which	3962	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	3963	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,	4170	EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE,
3883	EV_ASYNC_ENABLE, EV_CHILD_ENABLE.	4171	EV_ASYNC_ENABLE, EV_CHILD_ENABLE.
3884		4172
3885	If undefined or defined to be C<1> (and the platform supports it), then	4173	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	4174	the respective watcher type is supported. If defined to be C<0>, then it
3887	is not. Disabling watcher types mainly saves codesize.	4175	is not. Disabling watcher types mainly saves code size.
3888		4176
3889	=item EV_FEATURES	4177	=item EV_FEATURES
3890		4178
3891	If you need to shave off some kilobytes of code at the expense of some	4179	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	4180	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	4181	certain subsets of functionality. The default is to enable all features
3894	that can be enabled on the platform.	4182	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		4183
3899	A typical way to use this symbol is to define it to C<0> (or to a bitset	4184	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	4185	with some broad features you want) and then selectively re-enable
3901	additional parts you want, for example if you want everything minimal,	4186	additional parts you want, for example if you want everything minimal,
3902	but multiple event loop support, async and child watchers and the poll	4187	but multiple event loop support, async and child watchers and the poll
…		…
3915		4200
3916	=item C<1> - faster/larger code	4201	=item C<1> - faster/larger code
3917		4202
3918	Use larger code to speed up some operations.	4203	Use larger code to speed up some operations.
3919		4204
3920	Currently this is used to override some inlining decisions (enlarging the roughly	4205	Currently this is used to override some inlining decisions (enlarging the
3921	30% code size on amd64.	4206	code size by roughly 30% on amd64).
3922		4207
3923	When optimising for size, use of compiler flags such as C<-Os> with	4208	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	4209	gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of
3925	assertions.	4210	assertions.
3926		4211
3927	=item C<2> - faster/larger data structures	4212	=item C<2> - faster/larger data structures
3928		4213
3929	Replaces the small 2-heap for timer management by a faster 4-heap, larger	4214	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	4215	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	4216	and can additionally have an effect on the size of data structures at
3932	runtime.	4217	runtime.
3933		4218
3934	=item C<4> - full API configuration	4219	=item C<4> - full API configuration
3935		4220
3936	This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and	4221	This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and
3937	enables multiplicity (C<EV_MULTIPLICITY>=1).	4222	enables multiplicity (C<EV_MULTIPLICITY>=1).
3938		4223
		4224	=item C<8> - full API
		4225
3939	It also enables a lot of the "lesser used" core API functions. See C<ev.h>	4226	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	4227	details on which parts of the API are still available without this
3941	feature, and do not complain if this subset changes over time.	4228	feature, and do not complain if this subset changes over time.
3942		4229
3943	=item C<8> - enable all optional watcher types	4230	=item C<16> - enable all optional watcher types
3944		4231
3945	Enables all optional watcher types. If you want to selectively enable	4232	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,	4233	only some watcher types other than I/O and timers (e.g. prepare,
3947	embed, async, child...) you can enable them manually by defining	4234	embed, async, child...) you can enable them manually by defining
3948	C<EV_watchertype_ENABLE> to C<1> instead.	4235	C<EV_watchertype_ENABLE> to C<1> instead.
3949		4236
3950	=item C<16> - enable all backends	4237	=item C<32> - enable all backends
3951		4238
3952	This enables all backends - without this feature, you need to enable at	4239	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).	4240	least one backend manually (C<EV_USE_SELECT> is a good choice).
3954		4241
3955	=item C<32> - enable OS-specific "helper" APIs	4242	=item C<64> - enable OS-specific "helper" APIs
3956		4243
3957	Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by	4244	Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by
3958	default.	4245	default.
3959		4246
3960	=back	4247	=back
3961		4248
3962	Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0>	4249	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	4250	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	4251	code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O
3965	clock support.	4252	watchers, timers and monotonic clock support.
3966		4253
3967	With an intelligent-enough linker (gcc+binutils are intelligent enough	4254	With an intelligent-enough linker (gcc+binutils are intelligent enough
3968	when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by	4255	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	4256	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.	4257	I/O watcher then might come out at only 5Kb.
3971		4258
3972	=item EV_AVOID_STDIO	4259	=item EV_AVOID_STDIO
3973		4260
3974	If this is set to C<1> at compiletime, then libev will avoid using stdio	4261	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	4262	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	4263	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	4264	libc allows it, this avoids linking in the stdio library which is quite
3978	big.	4265	big.
3979		4266
3980	Note that error messages might become less precise when this option is	4267	Note that error messages might become less precise when this option is
…		…
3984		4271
3985	The highest supported signal number, +1 (or, the number of	4272	The highest supported signal number, +1 (or, the number of
3986	signals): Normally, libev tries to deduce the maximum number of signals	4273	signals): Normally, libev tries to deduce the maximum number of signals
3987	automatically, but sometimes this fails, in which case it can be	4274	automatically, but sometimes this fails, in which case it can be
3988	specified. Also, using a lower number than detected (C<32> should be	4275	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	4276	good for about any system in existence) can save some memory, as libev
3990	statically allocates some 12-24 bytes per signal number.	4277	statically allocates some 12-24 bytes per signal number.
3991		4278
3992	=item EV_PID_HASHSIZE	4279	=item EV_PID_HASHSIZE
3993		4280
3994	C<ev_child> watchers use a small hash table to distribute workload by	4281	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	4313	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
4027	will be C<0>.	4314	will be C<0>.
4028		4315
4029	=item EV_VERIFY	4316	=item EV_VERIFY
4030		4317
4031	Controls how much internal verification (see C<ev_loop_verify ()>) will	4318	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	4319	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	4320	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	4321	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	4322	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	4323	verification code will be called very frequently, which will slow down
…		…
4040	will be C<0>.	4327	will be C<0>.
4041		4328
4042	=item EV_COMMON	4329	=item EV_COMMON
4043		4330
4044	By default, all watchers have a C<void *data> member. By redefining	4331	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	4332	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,	4333	members. You have to define it each time you include one of the files,
4047	though, and it must be identical each time.	4334	though, and it must be identical each time.
4048		4335
4049	For example, the perl EV module uses something like this:	4336	For example, the perl EV module uses something like this:
4050		4337
…		…
4103	file.	4390	file.
4104		4391
4105	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	4392	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:	4393	that everybody includes and which overrides some configure choices:
4107		4394
4108	#define EV_FEATURES 0	4395	#define EV_FEATURES 8
4109	#define EV_USE_SELECT 1	4396	#define EV_USE_SELECT 1
		4397	#define EV_PREPARE_ENABLE 1
		4398	#define EV_IDLE_ENABLE 1
		4399	#define EV_SIGNAL_ENABLE 1
		4400	#define EV_CHILD_ENABLE 1
		4401	#define EV_USE_STDEXCEPT 0
4110	#define EV_CONFIG_H <config.h>	4402	#define EV_CONFIG_H <config.h>
4111		4403
4112	#include "ev++.h"	4404	#include "ev++.h"
4113		4405
4114	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	4406	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
…		…
4246	userdata *u = ev_userdata (EV_A);	4538	userdata *u = ev_userdata (EV_A);
4247	pthread_mutex_lock (&u->lock);	4539	pthread_mutex_lock (&u->lock);
4248	}	4540	}
4249		4541
4250	The event loop thread first acquires the mutex, and then jumps straight	4542	The event loop thread first acquires the mutex, and then jumps straight
4251	into C<ev_loop>:	4543	into C<ev_run>:
4252		4544
4253	void *	4545	void *
4254	l_run (void *thr_arg)	4546	l_run (void *thr_arg)
4255	{	4547	{
4256	struct ev_loop *loop = (struct ev_loop *)thr_arg;	4548	struct ev_loop *loop = (struct ev_loop *)thr_arg;
4257		4549
4258	l_acquire (EV_A);	4550	l_acquire (EV_A);
4259	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);	4551	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
4260	ev_loop (EV_A_ 0);	4552	ev_run (EV_A_ 0);
4261	l_release (EV_A);	4553	l_release (EV_A);
4262		4554
4263	return 0;	4555	return 0;
4264	}	4556	}
4265		4557
…		…
4317		4609
4318	=head3 COROUTINES	4610	=head3 COROUTINES
4319		4611
4320	Libev is very accommodating to coroutines ("cooperative threads"):	4612	Libev is very accommodating to coroutines ("cooperative threads"):
4321	libev fully supports nesting calls to its functions from different	4613	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	4614	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	4615	different coroutines, and switch freely between both coroutines running
4324	the loop, as long as you don't confuse yourself). The only exception is	4616	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.	4617	that you must not do this from C<ev_periodic> reschedule callbacks.
4326		4618
4327	Care has been taken to ensure that libev does not keep local state inside	4619	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	4620	C<ev_run>, and other calls do not usually allow for coroutine switches as
4329	they do not call any callbacks.	4621	they do not call any callbacks.
4330		4622
4331	=head2 COMPILER WARNINGS	4623	=head2 COMPILER WARNINGS
4332		4624
4333	Depending on your compiler and compiler settings, you might get no or a	4625	Depending on your compiler and compiler settings, you might get no or a
…		…
4344	maintainable.	4636	maintainable.
4345		4637
4346	And of course, some compiler warnings are just plain stupid, or simply	4638	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	4639	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	4640	seems to warn about). For example, certain older gcc versions had some
4349	warnings that resulted an extreme number of false positives. These have	4641	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	4642	been fixed, but some people still insist on making code warn-free with
4351	such buggy versions.	4643	such buggy versions.
4352		4644
4353	While libev is written to generate as few warnings as possible,	4645	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	4646	"warn-free" code is not a goal, and it is recommended not to build libev
…		…
4390	I suggest using suppression lists.	4682	I suggest using suppression lists.
4391		4683
4392		4684
4393	=head1 PORTABILITY NOTES	4685	=head1 PORTABILITY NOTES
4394		4686
		4687	=head2 GNU/LINUX 32 BIT LIMITATIONS
		4688
		4689	GNU/Linux is the only common platform that supports 64 bit file/large file
		4690	interfaces but I<disables> them by default.
		4691
		4692	That means that libev compiled in the default environment doesn't support
		4693	files larger than 2GiB or so, which mainly affects C<ev_stat> watchers.
		4694
		4695	Unfortunately, many programs try to work around this GNU/Linux issue
		4696	by enabling the large file API, which makes them incompatible with the
		4697	standard libev compiled for their system.
		4698
		4699	Likewise, libev cannot enable the large file API itself as this would
		4700	suddenly make it incompatible to the default compile time environment,
		4701	i.e. all programs not using special compile switches.
		4702
		4703	=head2 OS/X AND DARWIN BUGS
		4704
		4705	The whole thing is a bug if you ask me - basically any system interface
		4706	you touch is broken, whether it is locales, poll, kqueue or even the
		4707	OpenGL drivers.
		4708
		4709	=head3 C<kqueue> is buggy
		4710
		4711	The kqueue syscall is broken in all known versions - most versions support
		4712	only sockets, many support pipes.
		4713
		4714	Libev tries to work around this by not using C<kqueue> by default on this
		4715	rotten platform, but of course you can still ask for it when creating a
		4716	loop - embedding a socket-only kqueue loop into a select-based one is
		4717	probably going to work well.
		4718
		4719	=head3 C<poll> is buggy
		4720
		4721	Instead of fixing C<kqueue>, Apple replaced their (working) C<poll>
		4722	implementation by something calling C<kqueue> internally around the 10.5.6
		4723	release, so now C<kqueue> I<and> C<poll> are broken.
		4724
		4725	Libev tries to work around this by not using C<poll> by default on
		4726	this rotten platform, but of course you can still ask for it when creating
		4727	a loop.
		4728
		4729	=head3 C<select> is buggy
		4730
		4731	All that's left is C<select>, and of course Apple found a way to fuck this
		4732	one up as well: On OS/X, C<select> actively limits the number of file
		4733	descriptors you can pass in to 1024 - your program suddenly crashes when
		4734	you use more.
		4735
		4736	There is an undocumented "workaround" for this - defining
		4737	C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should>
		4738	work on OS/X.
		4739
		4740	=head2 SOLARIS PROBLEMS AND WORKAROUNDS
		4741
		4742	=head3 C<errno> reentrancy
		4743
		4744	The default compile environment on Solaris is unfortunately so
		4745	thread-unsafe that you can't even use components/libraries compiled
		4746	without C<-D_REENTRANT> in a threaded program, which, of course, isn't
		4747	defined by default. A valid, if stupid, implementation choice.
		4748
		4749	If you want to use libev in threaded environments you have to make sure
		4750	it's compiled with C<_REENTRANT> defined.
		4751
		4752	=head3 Event port backend
		4753
		4754	The scalable event interface for Solaris is called "event
		4755	ports". Unfortunately, this mechanism is very buggy in all major
		4756	releases. If you run into high CPU usage, your program freezes or you get
		4757	a large number of spurious wakeups, make sure you have all the relevant
		4758	and latest kernel patches applied. No, I don't know which ones, but there
		4759	are multiple ones to apply, and afterwards, event ports actually work
		4760	great.
		4761
		4762	If you can't get it to work, you can try running the program by setting
		4763	the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and
		4764	C<select> backends.
		4765
		4766	=head2 AIX POLL BUG
		4767
		4768	AIX unfortunately has a broken C<poll.h> header. Libev works around
		4769	this by trying to avoid the poll backend altogether (i.e. it's not even
		4770	compiled in), which normally isn't a big problem as C<select> works fine
		4771	with large bitsets on AIX, and AIX is dead anyway.
		4772
4395	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS	4773	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
		4774
		4775	=head3 General issues
4396		4776
4397	Win32 doesn't support any of the standards (e.g. POSIX) that libev	4777	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	4778	requires, and its I/O model is fundamentally incompatible with the POSIX
4399	model. Libev still offers limited functionality on this platform in	4779	model. Libev still offers limited functionality on this platform in
4400	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	4780	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
4401	descriptors. This only applies when using Win32 natively, not when using	4781	descriptors. This only applies when using Win32 natively, not when using
4402	e.g. cygwin.	4782	e.g. cygwin. Actually, it only applies to the microsofts own compilers,
		4783	as every compielr comes with a slightly differently broken/incompatible
		4784	environment.
4403		4785
4404	Lifting these limitations would basically require the full	4786	Lifting these limitations would basically require the full
4405	re-implementation of the I/O system. If you are into these kinds of	4787	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	4788	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).	4789	also that glib is the slowest event library known to man).
4408		4790
4409	There is no supported compilation method available on windows except	4791	There is no supported compilation method available on windows except
4410	embedding it into other applications.	4792	embedding it into other applications.
4411		4793
4412	Sensible signal handling is officially unsupported by Microsoft - libev	4794	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!):	4822	you do I<not> compile the F<ev.c> or any other embedded source files!):
4441		4823
4442	#include "evwrap.h"	4824	#include "evwrap.h"
4443	#include "ev.c"	4825	#include "ev.c"
4444		4826
4445	=over 4
4446
4447	=item The winsocket select function	4827	=head3 The winsocket C<select> function
4448		4828
4449	The winsocket C<select> function doesn't follow POSIX in that it	4829	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	4830	requires socket I<handles> and not socket I<file descriptors> (it is
4451	also extremely buggy). This makes select very inefficient, and also	4831	also extremely buggy). This makes select very inefficient, and also
4452	requires a mapping from file descriptors to socket handles (the Microsoft	4832	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 */	4841	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
4462		4842
4463	Note that winsockets handling of fd sets is O(n), so you can easily get a	4843	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.	4844	complexity in the O(n²) range when using win32.
4465		4845
4466	=item Limited number of file descriptors	4846	=head3 Limited number of file descriptors
4467		4847
4468	Windows has numerous arbitrary (and low) limits on things.	4848	Windows has numerous arbitrary (and low) limits on things.
4469		4849
4470	Early versions of winsocket's select only supported waiting for a maximum	4850	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	4851	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	4866	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,	4867	(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	4868	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.	4869	the cost of calling select (O(n²)) will likely make this unworkable.
4490		4870
4491	=back
4492
4493	=head2 PORTABILITY REQUIREMENTS	4871	=head2 PORTABILITY REQUIREMENTS
4494		4872
4495	In addition to a working ISO-C implementation and of course the	4873	In addition to a working ISO-C implementation and of course the
4496	backend-specific APIs, libev relies on a few additional extensions:	4874	backend-specific APIs, libev relies on a few additional extensions:
4497		4875
…		…
4503	Libev assumes not only that all watcher pointers have the same internal	4881	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	4882	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	4883	assumes that the same (machine) code can be used to call any watcher
4506	callback: The watcher callbacks have different type signatures, but libev	4884	callback: The watcher callbacks have different type signatures, but libev
4507	calls them using an C<ev_watcher *> internally.	4885	calls them using an C<ev_watcher *> internally.
		4886
		4887	=item pointer accesses must be thread-atomic
		4888
		4889	Accessing a pointer value must be atomic, it must both be readable and
		4890	writable in one piece - this is the case on all current architectures.
4508		4891
4509	=item C<sig_atomic_t volatile> must be thread-atomic as well	4892	=item C<sig_atomic_t volatile> must be thread-atomic as well
4510		4893
4511	The type C<sig_atomic_t volatile> (or whatever is defined as	4894	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	4895	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different
…		…
4535	watchers.	4918	watchers.
4536		4919
4537	=item C<double> must hold a time value in seconds with enough accuracy	4920	=item C<double> must hold a time value in seconds with enough accuracy
4538		4921
4539	The type C<double> is used to represent timestamps. It is required to	4922	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	4923	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	4924	good enough for at least into the year 4000 with millisecond accuracy
		4925	(the design goal for libev). This requirement is overfulfilled by
4542	implementations implementing IEEE 754, which is basically all existing	4926	implementations using IEEE 754, which is basically all existing ones. With
4543	ones. With IEEE 754 doubles, you get microsecond accuracy until at least	4927	IEEE 754 doubles, you get microsecond accuracy until at least 2200.
4544	2200.
4545		4928
4546	=back	4929	=back
4547		4930
4548	If you know of other additional requirements drop me a note.	4931	If you know of other additional requirements drop me a note.
4549		4932
…		…
4617	involves iterating over all running async watchers or all signal numbers.	5000	involves iterating over all running async watchers or all signal numbers.
4618		5001
4619	=back	5002	=back
4620		5003
4621		5004
		5005	=head1 PORTING FROM LIBEV 3.X TO 4.X
		5006
		5007	The major version 4 introduced some incompatible changes to the API.
		5008
		5009	At the moment, the C<ev.h> header file provides compatibility definitions
		5010	for all changes, so most programs should still compile. The compatibility
		5011	layer might be removed in later versions of libev, so better update to the
		5012	new API early than late.
		5013
		5014	=over 4
		5015
		5016	=item C<EV_COMPAT3> backwards compatibility mechanism
		5017
		5018	The backward compatibility mechanism can be controlled by
		5019	C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING>
		5020	section.
		5021
		5022	=item C<ev_default_destroy> and C<ev_default_fork> have been removed
		5023
		5024	These calls can be replaced easily by their C<ev_loop_xxx> counterparts:
		5025
		5026	ev_loop_destroy (EV_DEFAULT_UC);
		5027	ev_loop_fork (EV_DEFAULT);
		5028
		5029	=item function/symbol renames
		5030
		5031	A number of functions and symbols have been renamed:
		5032
		5033	ev_loop => ev_run
		5034	EVLOOP_NONBLOCK => EVRUN_NOWAIT
		5035	EVLOOP_ONESHOT => EVRUN_ONCE
		5036
		5037	ev_unloop => ev_break
		5038	EVUNLOOP_CANCEL => EVBREAK_CANCEL
		5039	EVUNLOOP_ONE => EVBREAK_ONE
		5040	EVUNLOOP_ALL => EVBREAK_ALL
		5041
		5042	EV_TIMEOUT => EV_TIMER
		5043
		5044	ev_loop_count => ev_iteration
		5045	ev_loop_depth => ev_depth
		5046	ev_loop_verify => ev_verify
		5047
		5048	Most functions working on C<struct ev_loop> objects don't have an
		5049	C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and
		5050	associated constants have been renamed to not collide with the C<struct
		5051	ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme
		5052	as all other watcher types. Note that C<ev_loop_fork> is still called
		5053	C<ev_loop_fork> because it would otherwise clash with the C<ev_fork>
		5054	typedef.
		5055
		5056	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>
		5057
		5058	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different
		5059	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile
		5060	and work, but the library code will of course be larger.
		5061
		5062	=back
		5063
		5064
4622	=head1 GLOSSARY	5065	=head1 GLOSSARY
4623		5066
4624	=over 4	5067	=over 4
4625		5068
4626	=item active	5069	=item active
4627		5070
4628	A watcher is active as long as it has been started (has been attached to	5071	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).	5072	See L<WATCHER STATES> for details.
4630		5073
4631	=item application	5074	=item application
4632		5075
4633	In this document, an application is whatever is using libev.	5076	In this document, an application is whatever is using libev.
		5077
		5078	=item backend
		5079
		5080	The part of the code dealing with the operating system interfaces.
4634		5081
4635	=item callback	5082	=item callback
4636		5083
4637	The address of a function that is called when some event has been	5084	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	5085	detected. Callbacks are being passed the event loop, the watcher that
4639	received the event, and the actual event bitset.	5086	received the event, and the actual event bitset.
4640		5087
4641	=item callback invocation	5088	=item callback/watcher invocation
4642		5089
4643	The act of calling the callback associated with a watcher.	5090	The act of calling the callback associated with a watcher.
4644		5091
4645	=item event	5092	=item event
4646		5093
4647	A change of state of some external event, such as data now being available	5094	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	5095	for reading on a file descriptor, time having passed or simply not having
4649	any other events happening anymore.	5096	any other events happening anymore.
4650		5097
4651	In libev, events are represented as single bits (such as C<EV_READ> or	5098	In libev, events are represented as single bits (such as C<EV_READ> or
4652	C<EV_TIMEOUT>).	5099	C<EV_TIMER>).
4653		5100
4654	=item event library	5101	=item event library
4655		5102
4656	A software package implementing an event model and loop.	5103	A software package implementing an event model and loop.
4657		5104
…		…
4665	The model used to describe how an event loop handles and processes	5112	The model used to describe how an event loop handles and processes
4666	watchers and events.	5113	watchers and events.
4667		5114
4668	=item pending	5115	=item pending
4669		5116
4670	A watcher is pending as soon as the corresponding event has been detected,	5117	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	5118	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		5119
4677	=item real time	5120	=item real time
4678		5121
4679	The physical time that is observed. It is apparently strictly monotonic :)	5122	The physical time that is observed. It is apparently strictly monotonic :)
4680		5123
…		…
4687	=item watcher	5130	=item watcher
4688		5131
4689	A data structure that describes interest in certain events. Watchers need	5132	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.	5133	to be started (attached to an event loop) before they can receive events.
4691		5134
4692	=item watcher invocation
4693
4694	The act of calling the callback associated with a watcher.
4695
4696	=back	5135	=back
4697		5136
4698	=head1 AUTHOR	5137	=head1 AUTHOR
4699		5138
4700	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson.	5139	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael
		5140	Magnusson and Emanuele Giaquinta.
4701		5141

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