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Revision 1.277 by root, Thu Dec 31 06:50:17 2009 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 is 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.	429	it possible to get the queued signal data. It can also simplify signal
		430	handling with threads, as long as you properly block signals in your
		431	threads that are not interested in handling them.
381		432
382	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
383	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
384	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.
385		448
386	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	449	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
387		450
388	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
389	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,
…		…
425	epoll scales either O(1) or O(active_fds).	488	epoll scales either O(1) or O(active_fds).
426		489
427	The epoll mechanism deserves honorable mention as the most misdesigned	490	The epoll mechanism deserves honorable mention as the most misdesigned
428	of the more advanced event mechanisms: mere annoyances include silently	491	of the more advanced event mechanisms: mere annoyances include silently
429	dropping file descriptors, requiring a system call per change per file	492	dropping file descriptors, requiring a system call per change per file
430	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
431	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
432	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
433	take considerable time (one syscall per file descriptor) and is of course	498	set, which can take considerable time (one syscall per file descriptor)
434	hard to detect.	499	and is of course hard to detect.
435		500
436	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
437	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
438	I<different> file descriptors (even already closed ones, so one cannot	503	I<different> file descriptors (even already closed ones, so one cannot
439	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
440	on SMP systems). Libev tries to counter these spurious notifications by	505	on SMP systems). Libev tries to counter these spurious notifications by
441	employing an additional generation counter and comparing that against the	506	employing an additional generation counter and comparing that against the
442	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.
443		512
444	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
445	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
446	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
447	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
…		…
513	=item C<EVBACKEND_PORT> (value 32, Solaris 10)	582	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
514		583
515	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,
516	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)).
517		586
518	Please note that Solaris event ports can deliver a lot of spurious
519	notifications, so you need to use non-blocking I/O or other means to avoid
520	blocking when no data (or space) is available.
521
522	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
523	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
524	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend	589	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend
525	might perform better.	590	might perform better.
526		591
527	On the positive side, with the exception of the spurious readiness	592	On the positive side, this backend actually performed fully to
528	notifications, this backend actually performed fully to specification
529	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
530	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.
531		602
532	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
533	C<EVBACKEND_POLL>.	604	C<EVBACKEND_POLL>.
534		605
535	=item C<EVBACKEND_ALL>	606	=item C<EVBACKEND_ALL>
536		607
537	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
538	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
539	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.	610	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.
540		611
541	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).
542		621
543	=back	622	=back
544		623
545	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,
546	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
547	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
548	()> will be tried.	627	()> will be tried.
549		628
550	Example: This is the most typical usage.
551
552	if (!ev_default_loop (0))
553	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
554
555	Example: Restrict libev to the select and poll backends, and do not allow
556	environment settings to be taken into account:
557
558	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
559
560	Example: Use whatever libev has to offer, but make sure that kqueue is
561	used if available (warning, breaks stuff, best use only with your own
562	private event loop and only if you know the OS supports your types of
563	fds):
564
565	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
566
567	=item struct ev_loop *ev_loop_new (unsigned int flags)
568
569	Similar to C<ev_default_loop>, but always creates a new event loop that is
570	always distinct from the default loop. Unlike the default loop, it cannot
571	handle signal and child watchers, and attempts to do so will be greeted by
572	undefined behaviour (or a failed assertion if assertions are enabled).
573
574	Note that this function I<is> thread-safe, and the recommended way to use
575	libev with threads is indeed to create one loop per thread, and using the
576	default loop in the "main" or "initial" thread.
577
578	Example: Try to create a event loop that uses epoll and nothing else.	629	Example: Try to create a event loop that uses epoll and nothing else.
579		630
580	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	631	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
581	if (!epoller)	632	if (!epoller)
582	fatal ("no epoll found here, maybe it hides under your chair");	633	fatal ("no epoll found here, maybe it hides under your chair");
583		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
584	=item ev_default_destroy ()	640	=item ev_loop_destroy (loop)
585		641
586	Destroys the default loop again (frees all memory and kernel state	642	Destroys an event loop object (frees all memory and kernel state
587	etc.). None of the active event watchers will be stopped in the normal	643	etc.). None of the active event watchers will be stopped in the normal
588	sense, so e.g. C<ev_is_active> might still return true. It is your	644	sense, so e.g. C<ev_is_active> might still return true. It is your
589	responsibility to either stop all watchers cleanly yourself I<before>	645	responsibility to either stop all watchers cleanly yourself I<before>
590	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
591	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
…		…
593		649
594	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
595	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
596	as signal and child watchers) would need to be stopped manually.	652	as signal and child watchers) would need to be stopped manually.
597		653
598	In general it is not advisable to call this function except in the	654	This function is normally used on loop objects allocated by
599	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.
600	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>
601	C<ev_loop_new> and C<ev_loop_destroy>.	661	and C<ev_loop_destroy>.
602		662
603	=item ev_loop_destroy (loop)	663	=item ev_loop_fork (loop)
604		664
605	Like C<ev_default_destroy>, but destroys an event loop created by an
606	earlier call to C<ev_loop_new>.
607
608	=item ev_default_fork ()
609
610	This function sets a flag that causes subsequent C<ev_loop> iterations	665	This function sets a flag that causes subsequent C<ev_run> iterations to
611	to reinitialise the kernel state for backends that have one. Despite the	666	reinitialise the kernel state for backends that have one. Despite the
612	name, you can call it anytime, but it makes most sense after forking, in	667	name, you can call it anytime, but it makes most sense after forking, in
613	the child process (or both child and parent, but that again makes little	668	the child process. You I<must> call it (or use C<EVFLAG_FORKCHECK>) in the
614	sense). You I<must> call it in the child before using any of the libev	669	child before resuming or calling C<ev_run>.
615	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.
616		675
617	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
618	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
619	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).
620		682
621	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
622	it just in case after a fork. To make this easy, the function will fit in	684	it just in case after a fork.
623	quite nicely into a call to C<pthread_atfork>:
624		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	...
625	pthread_atfork (0, 0, ev_default_fork);	696	pthread_atfork (0, 0, post_fork_child);
626
627	=item ev_loop_fork (loop)
628
629	Like C<ev_default_fork>, but acts on an event loop created by
630	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
631	after fork that you want to re-use in the child, and how you do this is
632	entirely your own problem.
633		697
634	=item int ev_is_default_loop (loop)	698	=item int ev_is_default_loop (loop)
635		699
636	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
637	otherwise.	701	otherwise.
638		702
639	=item unsigned int ev_loop_count (loop)	703	=item unsigned int ev_iteration (loop)
640		704
641	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
642	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>
643	happily wraps around with enough iterations.	707	and happily wraps around with enough iterations.
644		708
645	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
646	"ticks" the number of loop iterations), as it roughly corresponds with	710	"ticks" the number of loop iterations), as it roughly corresponds with
647	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.
648		713
649	=item unsigned int ev_loop_depth (loop)	714	=item unsigned int ev_depth (loop)
650		715
651	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
652	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.
653		718
654	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
655	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),
656	in which case it is higher.	721	in which case it is higher.
657		722
658	Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread	723	Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread,
659	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.
660		727
661	=item unsigned int ev_backend (loop)	728	=item unsigned int ev_backend (loop)
662		729
663	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
664	use.	731	use.
…		…
673		740
674	=item ev_now_update (loop)	741	=item ev_now_update (loop)
675		742
676	Establishes the current time by querying the kernel, updating the time	743	Establishes the current time by querying the kernel, updating the time
677	returned by C<ev_now ()> in the progress. This is a costly operation and	744	returned by C<ev_now ()> in the progress. This is a costly operation and
678	is usually done automatically within C<ev_loop ()>.	745	is usually done automatically within C<ev_run ()>.
679		746
680	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
681	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
682	the current time is a good idea.	749	the current time is a good idea.
683		750
…		…
685		752
686	=item ev_suspend (loop)	753	=item ev_suspend (loop)
687		754
688	=item ev_resume (loop)	755	=item ev_resume (loop)
689		756
690	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
691	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.
692		759
693	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
694	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
695	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
696	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>
…		…
698	C<ev_resume> directly afterwards to resume timer processing.	765	C<ev_resume> directly afterwards to resume timer processing.
699		766
700	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
701	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
702	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
703	occured while suspended).	770	occurred while suspended).
704		771
705	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
706	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>
707	without a previous call to C<ev_suspend>.	774	without a previous call to C<ev_suspend>.
708		775
709	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
710	event loop time (see C<ev_now_update>).	777	event loop time (see C<ev_now_update>).
711		778
712	=item ev_loop (loop, int flags)	779	=item ev_run (loop, int flags)
713		780
714	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
715	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
716	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>.
717		786
718	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
719	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.
720		790
721	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
722	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
723	finished (especially in interactive programs), but having a program	793	finished (especially in interactive programs), but having a program
724	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
725	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
726	beauty.	796	beauty.
727		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
728	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
729	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
730	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
731	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.
732		808
733	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
734	necessary) and will handle those and any already outstanding ones. It	810	necessary) and will handle those and any already outstanding ones. It
735	will block your process until at least one new event arrives (which could	811	will block your process until at least one new event arrives (which could
736	be an event internal to libev itself, so there is no guarantee that a	812	be an event internal to libev itself, so there is no guarantee that a
737	user-registered callback will be called), and will return after one	813	user-registered callback will be called), and will return after one
738	iteration of the loop.	814	iteration of the loop.
739		815
740	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
741	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
742	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
743	usually a better approach for this kind of thing.	819	usually a better approach for this kind of thing.
744		820
745	Here are the gory details of what C<ev_loop> does:	821	Here are the gory details of what C<ev_run> does:
746		822
		823	- Increment loop depth.
		824	- Reset the ev_break status.
747	- Before the first iteration, call any pending watchers.	825	- Before the first iteration, call any pending watchers.
		826	LOOP:
748	* If EVFLAG_FORKCHECK was used, check for a fork.	827	- If EVFLAG_FORKCHECK was used, check for a fork.
749	- 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.
750	- Queue and call all prepare watchers.	829	- Queue and call all prepare watchers.
		830	- If ev_break was called, goto FINISH.
751	- If we have been forked, detach and recreate the kernel state	831	- If we have been forked, detach and recreate the kernel state
752	as to not disturb the other process.	832	as to not disturb the other process.
753	- Update the kernel state with all outstanding changes.	833	- Update the kernel state with all outstanding changes.
754	- Update the "event loop time" (ev_now ()).	834	- Update the "event loop time" (ev_now ()).
755	- Calculate for how long to sleep or block, if at all	835	- Calculate for how long to sleep or block, if at all
756	(active idle watchers, EVLOOP_NONBLOCK or not having	836	(active idle watchers, EVRUN_NOWAIT or not having
757	any active watchers at all will result in not sleeping).	837	any active watchers at all will result in not sleeping).
758	- 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.
759	- Block the process, waiting for any events.	840	- Block the process, waiting for any events.
760	- Queue all outstanding I/O (fd) events.	841	- Queue all outstanding I/O (fd) events.
761	- 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.
762	- Queue all expired timers.	843	- Queue all expired timers.
763	- Queue all expired periodics.	844	- Queue all expired periodics.
764	- Unless any events are pending now, queue all idle watchers.	845	- Queue all idle watchers with priority higher than that of pending events.
765	- Queue all check watchers.	846	- Queue all check watchers.
766	- 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).
767	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
768	be handled here by queueing them when their watcher gets executed.	849	be handled here by queueing them when their watcher gets executed.
769	- 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
770	were used, or there are no active watchers, return, otherwise	851	were used, or there are no active watchers, goto FINISH, otherwise
771	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.
772		857
773	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
774	anymore.	859	anymore.
775		860
776	... queue jobs here, make sure they register event watchers as long	861	... queue jobs here, make sure they register event watchers as long
777	... as they still have work to do (even an idle watcher will do..)	862	... as they still have work to do (even an idle watcher will do..)
778	ev_loop (my_loop, 0);	863	ev_run (my_loop, 0);
779	... jobs done or somebody called unloop. yeah!	864	... jobs done or somebody called unloop. yeah!
780		865
781	=item ev_unloop (loop, how)	866	=item ev_break (loop, how)
782		867
783	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
784	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
785	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
786	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.
787		872
788	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>.
789		874
790	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.
791		877
792	=item ev_ref (loop)	878	=item ev_ref (loop)
793		879
794	=item ev_unref (loop)	880	=item ev_unref (loop)
795		881
796	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
797	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
798	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.
799		885
800	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
801	unregister, but that nevertheless should not keep C<ev_loop> from	887	unregister, but that nevertheless should not keep C<ev_run> from
802	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>	888	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>
803	before stopping it.	889	before stopping it.
804		890
805	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
806	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
807	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
808	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
809	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
810	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
811	before, respectively. Note also that libev might stop watchers itself	897	before, respectively. Note also that libev might stop watchers itself
812	(e.g. non-repeating timers) in which case you have to C<ev_ref>	898	(e.g. non-repeating timers) in which case you have to C<ev_ref>
813	in the callback).	899	in the callback).
814		900
815	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>
816	running when nothing else is active.	902	running when nothing else is active.
817		903
818	ev_signal exitsig;	904	ev_signal exitsig;
819	ev_signal_init (&exitsig, sig_cb, SIGINT);	905	ev_signal_init (&exitsig, sig_cb, SIGINT);
820	ev_signal_start (loop, &exitsig);	906	ev_signal_start (loop, &exitsig);
821	evf_unref (loop);	907	ev_unref (loop);
822		908
823	Example: For some weird reason, unregister the above signal handler again.	909	Example: For some weird reason, unregister the above signal handler again.
824		910
825	ev_ref (loop);	911	ev_ref (loop);
826	ev_signal_stop (loop, &exitsig);	912	ev_signal_stop (loop, &exitsig);
…		…
865	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>,
866	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
867	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
868	parallelity, then this setting will limit your transaction rate (if you	954	parallelity, then this setting will limit your transaction rate (if you
869	need to poll once per transaction and the I/O collect interval is 0.01,	955	need to poll once per transaction and the I/O collect interval is 0.01,
870	then you can't do more than 100 transations per second).	956	then you can't do more than 100 transactions per second).
871		957
872	Setting the I<timeout collect interval> can improve the opportunity for	958	Setting the I<timeout collect interval> can improve the opportunity for
873	saving power, as the program will "bundle" timer callback invocations that	959	saving power, as the program will "bundle" timer callback invocations that
874	are "near" in time together, by delaying some, thus reducing the number of	960	are "near" in time together, by delaying some, thus reducing the number of
875	times the process sleeps and wakes up again. Another useful technique to	961	times the process sleeps and wakes up again. Another useful technique to
…		…
883	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);	969	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);
884		970
885	=item ev_invoke_pending (loop)	971	=item ev_invoke_pending (loop)
886		972
887	This call will simply invoke all pending watchers while resetting their	973	This call will simply invoke all pending watchers while resetting their
888	pending state. Normally, C<ev_loop> does this automatically when required,	974	pending state. Normally, C<ev_run> does this automatically when required,
889	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).
890		980
891	=item int ev_pending_count (loop)	981	=item int ev_pending_count (loop)
892		982
893	Returns the number of pending watchers - zero indicates that no watchers	983	Returns the number of pending watchers - zero indicates that no watchers
894	are pending.	984	are pending.
895		985
896	=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))
897		987
898	This overrides the invoke pending functionality of the loop: Instead of	988	This overrides the invoke pending functionality of the loop: Instead of
899	invoking all pending watchers when there are any, C<ev_loop> will call	989	invoking all pending watchers when there are any, C<ev_run> will call
900	this callback instead. This is useful, for example, when you want to	990	this callback instead. This is useful, for example, when you want to
901	invoke the actual watchers inside another context (another thread etc.).	991	invoke the actual watchers inside another context (another thread etc.).
902		992
903	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
904	callback.	994	callback.
…		…
907		997
908	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
909	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
910	each call to a libev function.	1000	each call to a libev function.
911		1001
912	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
913	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
914	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
915	and I<acquire> callbacks on the loop.	1005	I<release> and I<acquire> callbacks on the loop.
916		1006
917	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
918	suspended waiting for new events, and C<acquire> is called just	1008	suspended waiting for new events, and C<acquire> is called just
919	afterwards.	1009	afterwards.
920		1010
…		…
923		1013
924	While event loop modifications are allowed between invocations of	1014	While event loop modifications are allowed between invocations of
925	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
926	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
927	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
928	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
929	to take note of any changes you made.	1019	to take note of any changes you made.
930		1020
931	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
932	invocations of C<release> and C<acquire>.	1022	invocations of C<release> and C<acquire>.
933		1023
934	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
935	document.	1025	document.
936		1026
937	=item ev_set_userdata (loop, void *data)	1027	=item ev_set_userdata (loop, void *data)
938		1028
939	=item ev_userdata (loop)	1029	=item void *ev_userdata (loop)
940		1030
941	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
942	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
943	C<0.>	1033	C<0>.
944		1034
945	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,
946	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
947	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
948	any other purpose as well.	1038	any other purpose as well.
949		1039
950	=item ev_loop_verify (loop)	1040	=item ev_verify (loop)
951		1041
952	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
953	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
954	through all internal structures and checks them for validity. If anything	1044	through all internal structures and checks them for validity. If anything
955	is found to be inconsistent, it will print an error message to standard	1045	is found to be inconsistent, it will print an error message to standard
…		…
966		1056
967	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
968	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
969	watchers and C<ev_io_start> for I/O watchers.	1059	watchers and C<ev_io_start> for I/O watchers.
970		1060
971	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
972	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
973	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:
974		1065
975	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)
976	{	1067	{
977	ev_io_stop (w);	1068	ev_io_stop (w);
978	ev_unloop (loop, EVUNLOOP_ALL);	1069	ev_break (loop, EVBREAK_ALL);
979	}	1070	}
980		1071
981	struct ev_loop *loop = ev_default_loop (0);	1072	struct ev_loop *loop = ev_default_loop (0);
982		1073
983	ev_io stdin_watcher;	1074	ev_io stdin_watcher;
984		1075
985	ev_init (&stdin_watcher, my_cb);	1076	ev_init (&stdin_watcher, my_cb);
986	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	1077	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
987	ev_io_start (loop, &stdin_watcher);	1078	ev_io_start (loop, &stdin_watcher);
988		1079
989	ev_loop (loop, 0);	1080	ev_run (loop, 0);
990		1081
991	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
992	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
993	stack).	1084	stack).
994		1085
995	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>
996	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).
997		1088
998	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
999	(watcher *, callback)>, which expects a callback to be provided. This	1090	*, callback)>, which expects a callback to be provided. This callback is
1000	callback gets invoked each time the event occurs (or, in the case of I/O	1091	invoked each time the event occurs (or, in the case of I/O watchers, each
1001	watchers, each time the event loop detects that the file descriptor given	1092	time the event loop detects that the file descriptor given is readable
1002	is readable and/or writable).	1093	and/or writable).
1003		1094
1004	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 *, ...) >>
1005	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
1006	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<<
1007	ev_TYPE_init (watcher *, callback, ...) >>.	1098	ev_TYPE_init (watcher *, callback, ...) >>.
…		…
1030	=item C<EV_WRITE>	1121	=item C<EV_WRITE>
1031		1122
1032	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
1033	writable.	1124	writable.
1034		1125
1035	=item C<EV_TIMEOUT>	1126	=item C<EV_TIMER>
1036		1127
1037	The C<ev_timer> watcher has timed out.	1128	The C<ev_timer> watcher has timed out.
1038		1129
1039	=item C<EV_PERIODIC>	1130	=item C<EV_PERIODIC>
1040		1131
…		…
1058		1149
1059	=item C<EV_PREPARE>	1150	=item C<EV_PREPARE>
1060		1151
1061	=item C<EV_CHECK>	1152	=item C<EV_CHECK>
1062		1153
1063	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
1064	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
1065	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
1066	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
1067	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
1068	(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
1069	C<ev_loop> from blocking).	1160	C<ev_run> from blocking).
1070		1161
1071	=item C<EV_EMBED>	1162	=item C<EV_EMBED>
1072		1163
1073	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.
1074		1165
1075	=item C<EV_FORK>	1166	=item C<EV_FORK>
1076		1167
1077	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
1078	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>).
1079		1174
1080	=item C<EV_ASYNC>	1175	=item C<EV_ASYNC>
1081		1176
1082	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>).
1083		1178
…		…
1255		1350
1256	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
1257	functions that do not need a watcher.	1352	functions that do not need a watcher.
1258		1353
1259	=back	1354	=back
1260
1261		1355
1262	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	1356	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
1263		1357
1264	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
1265	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
…		…
1321	t2_cb (EV_P_ ev_timer *w, int revents)	1415	t2_cb (EV_P_ ev_timer *w, int revents)
1322	{	1416	{
1323	struct my_biggy big = (struct my_biggy *)	1417	struct my_biggy big = (struct my_biggy *)
1324	(((char *)w) - offsetof (struct my_biggy, t2));	1418	(((char *)w) - offsetof (struct my_biggy, t2));
1325	}	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
1326		1479
1327	=head2 WATCHER PRIORITY MODELS	1480	=head2 WATCHER PRIORITY MODELS
1328		1481
1329	Many event loops support I<watcher priorities>, which are usually small	1482	Many event loops support I<watcher priorities>, which are usually small
1330	integers that influence the ordering of event callback invocation	1483	integers that influence the ordering of event callback invocation
…		…
1373		1526
1374	For example, to emulate how many other event libraries handle priorities,	1527	For example, to emulate how many other event libraries handle priorities,
1375	you can associate an C<ev_idle> watcher to each such watcher, and in	1528	you can associate an C<ev_idle> watcher to each such watcher, and in
1376	the normal watcher callback, you just start the idle watcher. The real	1529	the normal watcher callback, you just start the idle watcher. The real
1377	processing is done in the idle watcher callback. This causes libev to	1530	processing is done in the idle watcher callback. This causes libev to
1378	continously poll and process kernel event data for the watcher, but when	1531	continuously poll and process kernel event data for the watcher, but when
1379	the lock-out case is known to be rare (which in turn is rare :), this is	1532	the lock-out case is known to be rare (which in turn is rare :), this is
1380	workable.	1533	workable.
1381		1534
1382	Usually, however, the lock-out model implemented that way will perform	1535	Usually, however, the lock-out model implemented that way will perform
1383	miserably under the type of load it was designed to handle. In that case,	1536	miserably under the type of load it was designed to handle. In that case,
…		…
1397	{	1550	{
1398	// stop the I/O watcher, we received the event, but	1551	// stop the I/O watcher, we received the event, but
1399	// are not yet ready to handle it.	1552	// are not yet ready to handle it.
1400	ev_io_stop (EV_A_ w);	1553	ev_io_stop (EV_A_ w);
1401		1554
1402	// start the idle watcher to ahndle the actual event.	1555	// start the idle watcher to handle the actual event.
1403	// it will not be executed as long as other watchers	1556	// it will not be executed as long as other watchers
1404	// with the default priority are receiving events.	1557	// with the default priority are receiving events.
1405	ev_idle_start (EV_A_ &idle);	1558	ev_idle_start (EV_A_ &idle);
1406	}	1559	}
1407		1560
…		…
1461		1614
1462	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
1463	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
1464	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
1465	descriptors for which non-blocking operation makes no sense (such as	1618	descriptors for which non-blocking operation makes no sense (such as
1466	files) - libev doesn't guarentee any specific behaviour in that case.	1619	files) - libev doesn't guarantee any specific behaviour in that case.
1467		1620
1468	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
1469	receive "spurious" readiness notifications, that is your callback might	1622	receive "spurious" readiness notifications, that is your callback might
1470	be called with C<EV_READ> but a subsequent C<read>(2) will actually block	1623	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
1471	because there is no data. Not only are some backends known to create a	1624	because there is no data. Not only are some backends known to create a
…		…
1536		1689
1537	So when you encounter spurious, unexplained daemon exits, make sure you	1690	So when you encounter spurious, unexplained daemon exits, make sure you
1538	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon	1691	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon
1539	somewhere, as that would have given you a big clue).	1692	somewhere, as that would have given you a big clue).
1540		1693
		1694	=head3 The special problem of accept()ing when you can't
		1695
		1696	Many implementations of the POSIX C<accept> function (for example,
		1697	found in post-2004 Linux) have the peculiar behaviour of not removing a
		1698	connection from the pending queue in all error cases.
		1699
		1700	For example, larger servers often run out of file descriptors (because
		1701	of resource limits), causing C<accept> to fail with C<ENFILE> but not
		1702	rejecting the connection, leading to libev signalling readiness on
		1703	the next iteration again (the connection still exists after all), and
		1704	typically causing the program to loop at 100% CPU usage.
		1705
		1706	Unfortunately, the set of errors that cause this issue differs between
		1707	operating systems, there is usually little the app can do to remedy the
		1708	situation, and no known thread-safe method of removing the connection to
		1709	cope with overload is known (to me).
		1710
		1711	One of the easiest ways to handle this situation is to just ignore it
		1712	- when the program encounters an overload, it will just loop until the
		1713	situation is over. While this is a form of busy waiting, no OS offers an
		1714	event-based way to handle this situation, so it's the best one can do.
		1715
		1716	A better way to handle the situation is to log any errors other than
		1717	C<EAGAIN> and C<EWOULDBLOCK>, making sure not to flood the log with such
		1718	messages, and continue as usual, which at least gives the user an idea of
		1719	what could be wrong ("raise the ulimit!"). For extra points one could stop
		1720	the C<ev_io> watcher on the listening fd "for a while", which reduces CPU
		1721	usage.
		1722
		1723	If your program is single-threaded, then you could also keep a dummy file
		1724	descriptor for overload situations (e.g. by opening F</dev/null>), and
		1725	when you run into C<ENFILE> or C<EMFILE>, close it, run C<accept>,
		1726	close that fd, and create a new dummy fd. This will gracefully refuse
		1727	clients under typical overload conditions.
		1728
		1729	The last way to handle it is to simply log the error and C<exit>, as
		1730	is often done with C<malloc> failures, but this results in an easy
		1731	opportunity for a DoS attack.
1541		1732
1542	=head3 Watcher-Specific Functions	1733	=head3 Watcher-Specific Functions
1543		1734
1544	=over 4	1735	=over 4
1545		1736
…		…
1577	...	1768	...
1578	struct ev_loop *loop = ev_default_init (0);	1769	struct ev_loop *loop = ev_default_init (0);
1579	ev_io stdin_readable;	1770	ev_io stdin_readable;
1580	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);
1581	ev_io_start (loop, &stdin_readable);	1772	ev_io_start (loop, &stdin_readable);
1582	ev_loop (loop, 0);	1773	ev_run (loop, 0);
1583		1774
1584		1775
1585	=head2 C<ev_timer> - relative and optionally repeating timeouts	1776	=head2 C<ev_timer> - relative and optionally repeating timeouts
1586		1777
1587	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
…		…
1596	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
1597	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
1598	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
1599	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
1600	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
1601	no longer true when a callback calls C<ev_loop> recursively).	1792	no longer true when a callback calls C<ev_run> recursively).
1602		1793
1603	=head3 Be smart about timeouts	1794	=head3 Be smart about timeouts
1604		1795
1605	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
1606	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,
…		…
1692	ev_tstamp timeout = last_activity + 60.;	1883	ev_tstamp timeout = last_activity + 60.;
1693		1884
1694	// 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
1695	if (timeout < now)	1886	if (timeout < now)
1696	{	1887	{
1697	// timeout occured, take action	1888	// timeout occurred, take action
1698	}	1889	}
1699	else	1890	else
1700	{	1891	{
1701	// callback was invoked, but there was some activity, re-arm	1892	// callback was invoked, but there was some activity, re-arm
1702	// the watcher to fire in last_activity + 60, which is	1893	// the watcher to fire in last_activity + 60, which is
…		…
1724	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
1725	callback, which will "do the right thing" and start the timer:	1916	callback, which will "do the right thing" and start the timer:
1726		1917
1727	ev_init (timer, callback);	1918	ev_init (timer, callback);
1728	last_activity = ev_now (loop);	1919	last_activity = ev_now (loop);
1729	callback (loop, timer, EV_TIMEOUT);	1920	callback (loop, timer, EV_TIMER);
1730		1921
1731	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
1732	C<last_activity>, no libev calls at all:	1923	C<last_activity>, no libev calls at all:
1733		1924
1734	last_actiivty = ev_now (loop);	1925	last_activity = ev_now (loop);
1735		1926
1736	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
1737	time-out is unlikely to be triggered, much more efficient.	1928	time-out is unlikely to be triggered, much more efficient.
1738		1929
1739	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
…		…
1777		1968
1778	=head3 The special problem of time updates	1969	=head3 The special problem of time updates
1779		1970
1780	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
1781	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
1782	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
1783	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
1784	lots of events in one iteration.	1975	lots of events in one iteration.
1785		1976
1786	The relative timeouts are calculated relative to the C<ev_now ()>	1977	The relative timeouts are calculated relative to the C<ev_now ()>
1787	time. This is usually the right thing as this timestamp refers to the time	1978	time. This is usually the right thing as this timestamp refers to the time
…		…
1865	Returns the remaining time until a timer fires. If the timer is active,	2056	Returns the remaining time until a timer fires. If the timer is active,
1866	then this time is relative to the current event loop time, otherwise it's	2057	then this time is relative to the current event loop time, otherwise it's
1867	the timeout value currently configured.	2058	the timeout value currently configured.
1868		2059
1869	That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns	2060	That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns
1870	C<5>. When the timer is started and one second passes, C<ev_timer_remain>	2061	C<5>. When the timer is started and one second passes, C<ev_timer_remaining>
1871	will return C<4>. When the timer expires and is restarted, it will return	2062	will return C<4>. When the timer expires and is restarted, it will return
1872	roughly C<7> (likely slightly less as callback invocation takes some time,	2063	roughly C<7> (likely slightly less as callback invocation takes some time,
1873	too), and so on.	2064	too), and so on.
1874		2065
1875	=item ev_tstamp repeat [read-write]	2066	=item ev_tstamp repeat [read-write]
…		…
1904	}	2095	}
1905		2096
1906	ev_timer mytimer;	2097	ev_timer mytimer;
1907	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 */
1908	ev_timer_again (&mytimer); /* start timer */	2099	ev_timer_again (&mytimer); /* start timer */
1909	ev_loop (loop, 0);	2100	ev_run (loop, 0);
1910		2101
1911	// 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":
1912	// reset the timeout to start ticking again at 10 seconds	2103	// reset the timeout to start ticking again at 10 seconds
1913	ev_timer_again (&mytimer);	2104	ev_timer_again (&mytimer);
1914		2105
…		…
1940		2131
1941	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
1942	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
1943	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
1944	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
1945	(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).
1946		2137
1947	=head3 Watcher-Specific Functions and Data Members	2138	=head3 Watcher-Specific Functions and Data Members
1948		2139
1949	=over 4	2140	=over 4
1950		2141
…		…
2078	Example: Call a callback every hour, or, more precisely, whenever the	2269	Example: Call a callback every hour, or, more precisely, whenever the
2079	system time is divisible by 3600. The callback invocation times have	2270	system time is divisible by 3600. The callback invocation times have
2080	potentially a lot of jitter, but good long-term stability.	2271	potentially a lot of jitter, but good long-term stability.
2081		2272
2082	static void	2273	static void
2083	clock_cb (struct ev_loop *loop, ev_io *w, int revents)	2274	clock_cb (struct ev_loop *loop, ev_periodic *w, int revents)
2084	{	2275	{
2085	... 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)
2086	}	2277	}
2087		2278
2088	ev_periodic hourly_tick;	2279	ev_periodic hourly_tick;
…		…
2111		2302
2112	=head2 C<ev_signal> - signal me when a signal gets signalled!	2303	=head2 C<ev_signal> - signal me when a signal gets signalled!
2113		2304
2114	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
2115	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
2116	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
2117	normal event processing, like any other event.	2308	normal event processing, like any other event.
2118		2309
2119	If you want signals to be delivered truly asynchronously, just use	2310	If you want signals to be delivered truly asynchronously, just use
2120	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
2121	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
…		…
2160	In current versions of libev, the signal will not be blocked indefinitely	2351	In current versions of libev, the signal will not be blocked indefinitely
2161	unless you use the C<signalfd> API (C<EV_SIGNALFD>). While this reduces	2352	unless you use the C<signalfd> API (C<EV_SIGNALFD>). While this reduces
2162	the window of opportunity for problems, it will not go away, as libev	2353	the window of opportunity for problems, it will not go away, as libev
2163	I<has> to modify the signal mask, at least temporarily.	2354	I<has> to modify the signal mask, at least temporarily.
2164		2355
2165	So I can't stress this enough I<if you do not reset your signal mask	2356	So I can't stress this enough: I<If you do not reset your signal mask when
2166	when you expect it to be empty, you have a race condition in your	2357	you expect it to be empty, you have a race condition in your code>. This
2167	program>. This is not a libev-specific thing, this is true for most event	2358	is not a libev-specific thing, this is true for most event libraries.
2168	libraries.	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>.
2169		2373
2170	=head3 Watcher-Specific Functions and Data Members	2374	=head3 Watcher-Specific Functions and Data Members
2171		2375
2172	=over 4	2376	=over 4
2173		2377
…		…
2189	Example: Try to exit cleanly on SIGINT.	2393	Example: Try to exit cleanly on SIGINT.
2190		2394
2191	static void	2395	static void
2192	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)	2396	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)
2193	{	2397	{
2194	ev_unloop (loop, EVUNLOOP_ALL);	2398	ev_break (loop, EVBREAK_ALL);
2195	}	2399	}
2196		2400
2197	ev_signal signal_watcher;	2401	ev_signal signal_watcher;
2198	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	2402	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
2199	ev_signal_start (loop, &signal_watcher);	2403	ev_signal_start (loop, &signal_watcher);
…		…
2585		2789
2586	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:
2587	prepare watchers get invoked before the process blocks and check watchers	2791	prepare watchers get invoked before the process blocks and check watchers
2588	afterwards.	2792	afterwards.
2589		2793
2590	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
2591	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>
2592	watchers. Other loops than the current one are fine, however. The	2796	watchers. Other loops than the current one are fine, however. The
2593	rationale behind this is that you do not need to check for recursion in	2797	rationale behind this is that you do not need to check for recursion in
2594	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,	2798	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,
2595	C<ev_check> so if you have one watcher of each kind they will always be	2799	C<ev_check> so if you have one watcher of each kind they will always be
…		…
2763		2967
2764	if (timeout >= 0)	2968	if (timeout >= 0)
2765	// create/start timer	2969	// create/start timer
2766		2970
2767	// poll	2971	// poll
2768	ev_loop (EV_A_ 0);	2972	ev_run (EV_A_ 0);
2769		2973
2770	// stop timer again	2974	// stop timer again
2771	if (timeout >= 0)	2975	if (timeout >= 0)
2772	ev_timer_stop (EV_A_ &to);	2976	ev_timer_stop (EV_A_ &to);
2773		2977
…		…
2851	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).
2852		3056
2853	=item ev_embed_sweep (loop, ev_embed *)	3057	=item ev_embed_sweep (loop, ev_embed *)
2854		3058
2855	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
2856	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
2857	appropriate way for embedded loops.	3061	appropriate way for embedded loops.
2858		3062
2859	=item struct ev_loop *other [read-only]	3063	=item struct ev_loop *other [read-only]
2860		3064
2861	The embedded event loop.	3065	The embedded event loop.
…		…
2921	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
2922	handlers will be invoked, too, of course.	3126	handlers will be invoked, too, of course.
2923		3127
2924	=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?
2925		3129
2926	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
2927	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
2928	sequence should be handled by libev without any problems.	3132	sequence should be handled by libev without any problems.
2929		3133
2930	This changes when the application actually wants to do event handling	3134	This changes when the application actually wants to do event handling
2931	in the child, or both parent in child, in effect "continuing" after the	3135	in the child, or both parent in child, in effect "continuing" after the
…		…
2947	disadvantage of having to use multiple event loops (which do not support	3151	disadvantage of having to use multiple event loops (which do not support
2948	signal watchers).	3152	signal watchers).
2949		3153
2950	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
2951	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
2952	C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying	3156	C<ev_loop_destroy (EV_DEFAULT)> followed by C<ev_default_loop (...)>.
2953	the default loop will "orphan" (not stop) all registered watchers, so you	3157	Destroying the default loop will "orphan" (not stop) all registered
2954	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
2955	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.
2956		3161
2957	=head3 Watcher-Specific Functions and Data Members	3162	=head3 Watcher-Specific Functions and Data Members
2958		3163
2959	=over 4	3164	=over 4
2960		3165
2961	=item ev_fork_init (ev_signal *, callback)	3166	=item ev_fork_init (ev_fork *, callback)
2962		3167
2963	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
2964	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,
2965	believe me.	3170	really.
2966		3171
2967	=back	3172	=back
2968		3173
2969		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
2970	=head2 C<ev_async> - how to wake up another event loop	3215	=head2 C<ev_async> - how to wake up an event loop
2971		3216
2972	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
2973	asynchronous sources such as signal handlers (as opposed to multiple event	3218	asynchronous sources such as signal handlers (as opposed to multiple event
2974	loops - those are of course safe to use in different threads).	3219	loops - those are of course safe to use in different threads).
2975		3220
2976	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,
2977	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>
2978	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
2979	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.
2980	safe.
2981		3225
2982	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,
2983	too, are asynchronous in nature, and signals, too, will be compressed	3227	too, are asynchronous in nature, and signals, too, will be compressed
2984	(i.e. the number of callback invocations may be less than the number of	3228	(i.e. the number of callback invocations may be less than the number of
2985	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.
2986		3233
2987	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
2988	just the default loop.	3235	just the default loop.
2989		3236
2990	=head3 Queueing	3237	=head3 Queueing
…		…
3140		3387
3141	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
3142	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
3143	repeat = 0) will be started. C<0> is a valid timeout.	3390	repeat = 0) will be started. C<0> is a valid timeout.
3144		3391
3145	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
3146	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
3147	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>
3148	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>
3149	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
3150	events precedence.	3397	events precedence.
3151		3398
3152	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.
3153		3400
3154	static void stdin_ready (int revents, void *arg)	3401	static void stdin_ready (int revents, void *arg)
3155	{	3402	{
3156	if (revents & EV_READ)	3403	if (revents & EV_READ)
3157	/* stdin might have data for us, joy! */;	3404	/* stdin might have data for us, joy! */;
3158	else if (revents & EV_TIMEOUT)	3405	else if (revents & EV_TIMER)
3159	/* doh, nothing entered */;	3406	/* doh, nothing entered */;
3160	}	3407	}
3161		3408
3162	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	3409	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
3163		3410
…		…
3166	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
3167	the given events it.	3414	the given events it.
3168		3415
3169	=item ev_feed_signal_event (loop, int signum)	3416	=item ev_feed_signal_event (loop, int signum)
3170		3417
3171	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>,
3172	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;
3173		3470
3174	=back	3471	=back
3175		3472
3176		3473
3177	=head1 LIBEVENT EMULATION	3474	=head1 LIBEVENT EMULATION
3178		3475
3179	Libev offers a compatibility emulation layer for libevent. It cannot	3476	Libev offers a compatibility emulation layer for libevent. It cannot
3180	emulate the internals of libevent, so here are some usage hints:	3477	emulate the internals of libevent, so here are some usage hints:
3181		3478
3182	=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.
3183		3485
3184	=item * Use it by including <event.h>, as usual.	3486	=item * Use it by including <event.h>, as usual.
3185		3487
3186	=item * The following members are fully supported: ev_base, ev_callback,	3488	=item * The following members are fully supported: ev_base, ev_callback,
3187	ev_arg, ev_fd, ev_res, ev_events.	3489	ev_arg, ev_fd, ev_res, ev_events.
…		…
3193	=item * Priorities are not currently supported. Initialising priorities	3495	=item * Priorities are not currently supported. Initialising priorities
3194	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
3195	is an ev_pri field.	3497	is an ev_pri field.
3196		3498
3197	=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
3198	first base created (== the default loop) gets the signals.	3500	base that registered the signal gets the signals.
3199		3501
3200	=item * Other members are not supported.	3502	=item * Other members are not supported.
3201		3503
3202	=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
3203	to use the libev header file and library.	3505	to use the libev header file and library.
…		…
3222	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++
3223	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
3224	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
3225	you disable C<EV_MULTIPLICITY> when embedding libev).	3527	you disable C<EV_MULTIPLICITY> when embedding libev).
3226		3528
3227	Currently, functions, and static and non-static member functions can be	3529	Currently, functions, static and non-static member functions and classes
3228	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
3229	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
3230	types of functors please contact the author (preferably after implementing	3532	you need support for other types of functors please contact the author
3231	it).	3533	(preferably after implementing it).
3232		3534
3233	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:
3234		3536
3235	=over 4	3537	=over 4
3236		3538
…		…
3297	myclass obj;	3599	myclass obj;
3298	ev::io iow;	3600	ev::io iow;
3299	iow.set <myclass, &myclass::io_cb> (&obj);	3601	iow.set <myclass, &myclass::io_cb> (&obj);
3300		3602
3301	=item w->set (object *)	3603	=item w->set (object *)
3302
3303	This is an B<experimental> feature that might go away in a future version.
3304		3604
3305	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
3306	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
3307	functor objects without having to manually specify the C<operator ()> all	3607	functor objects without having to manually specify the C<operator ()> all
3308	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
…		…
3348	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
3349	do this when the watcher is inactive (and not pending either).	3649	do this when the watcher is inactive (and not pending either).
3350		3650
3351	=item w->set ([arguments])	3651	=item w->set ([arguments])
3352		3652
3353	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
3354	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
3355	automatically stopped and restarted when reconfiguring it with this	3655	C counterpart, an active watcher gets automatically stopped and restarted
3356	method.	3656	when reconfiguring it with this method.
3357		3657
3358	=item w->start ()	3658	=item w->start ()
3359		3659
3360	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
3361	constructor already stores the event loop.	3661	constructor already stores the event loop.
3362		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
3363	=item w->stop ()	3669	=item w->stop ()
3364		3670
3365	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.
3366		3672
3367	=item w->again () (C<ev::timer>, C<ev::periodic> only)	3673	=item w->again () (C<ev::timer>, C<ev::periodic> only)
…		…
3379		3685
3380	=back	3686	=back
3381		3687
3382	=back	3688	=back
3383		3689
3384	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
3385	the constructor.	3691	watchers in the constructor.
3386		3692
3387	class myclass	3693	class myclass
3388	{	3694	{
3389	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);
3390	ev::idle idle; void idle_cb (ev::idle &w, int revents);	3697	ev::idle idle; void idle_cb (ev::idle &w, int revents);
3391		3698
3392	myclass (int fd)	3699	myclass (int fd)
3393	{	3700	{
3394	io .set <myclass, &myclass::io_cb > (this);	3701	io .set <myclass, &myclass::io_cb > (this);
		3702	io2 .set <myclass, &myclass::io2_cb > (this);
3395	idle.set <myclass, &myclass::idle_cb> (this);	3703	idle.set <myclass, &myclass::idle_cb> (this);
3396		3704
3397	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
3398	}	3709	}
3399	};	3710	};
3400		3711
3401		3712
3402	=head1 OTHER LANGUAGE BINDINGS	3713	=head1 OTHER LANGUAGE BINDINGS
…		…
3450	Erkki Seppala has written Ocaml bindings for libev, to be found at	3761	Erkki Seppala has written Ocaml bindings for libev, to be found at
3451	L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>.	3762	L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>.
3452		3763
3453	=item Lua	3764	=item Lua
3454		3765
3455	Brian Maher has written a partial interface to libev	3766	Brian Maher has written a partial interface to libev for lua (at the
3456	for lua (only C<ev_io> and C<ev_timer>), to be found at	3767	time of this writing, only C<ev_io> and C<ev_timer>), to be found at
3457	L<http://github.com/brimworks/lua-ev>.	3768	L<http://github.com/brimworks/lua-ev>.
3458		3769
3459	=back	3770	=back
3460		3771
3461		3772
…		…
3476	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,
3477	C<EV_A_> is used when other arguments are following. Example:	3788	C<EV_A_> is used when other arguments are following. Example:
3478		3789
3479	ev_unref (EV_A);	3790	ev_unref (EV_A);
3480	ev_timer_add (EV_A_ watcher);	3791	ev_timer_add (EV_A_ watcher);
3481	ev_loop (EV_A_ 0);	3792	ev_run (EV_A_ 0);
3482		3793
3483	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,
3484	which is often provided by the following macro.	3795	which is often provided by the following macro.
3485		3796
3486	=item C<EV_P>, C<EV_P_>	3797	=item C<EV_P>, C<EV_P_>
…		…
3526	}	3837	}
3527		3838
3528	ev_check check;	3839	ev_check check;
3529	ev_check_init (&check, check_cb);	3840	ev_check_init (&check, check_cb);
3530	ev_check_start (EV_DEFAULT_ &check);	3841	ev_check_start (EV_DEFAULT_ &check);
3531	ev_loop (EV_DEFAULT_ 0);	3842	ev_run (EV_DEFAULT_ 0);
3532		3843
3533	=head1 EMBEDDING	3844	=head1 EMBEDDING
3534		3845
3535	Libev can (and often is) directly embedded into host	3846	Libev can (and often is) directly embedded into host
3536	applications. Examples of applications that embed it include the Deliantra	3847	applications. Examples of applications that embed it include the Deliantra
…		…
3616	libev.m4	3927	libev.m4
3617		3928
3618	=head2 PREPROCESSOR SYMBOLS/MACROS	3929	=head2 PREPROCESSOR SYMBOLS/MACROS
3619		3930
3620	Libev can be configured via a variety of preprocessor symbols you have to	3931	Libev can be configured via a variety of preprocessor symbols you have to
3621	define before including any of its files. The default in the absence of	3932	define before including (or compiling) any of its files. The default in
3622	autoconf is documented for every option.	3933	the absence of autoconf is documented for every option.
		3934
		3935	Symbols marked with "(h)" do not change the ABI, and can have different
		3936	values when compiling libev vs. including F<ev.h>, so it is permissible
		3937	to redefine them before including F<ev.h> without breaking compatibility
		3938	to a compiled library. All other symbols change the ABI, which means all
		3939	users of libev and the libev code itself must be compiled with compatible
		3940	settings.
3623		3941
3624	=over 4	3942	=over 4
3625		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.
		3959
3626	=item EV_STANDALONE	3960	=item EV_STANDALONE (h)
3627		3961
3628	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
3629	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
3630	implementations for some libevent functions (such as logging, which is not	3964	implementations for some libevent functions (such as logging, which is not
3631	supported). It will also not define any of the structs usually found in	3965	supported). It will also not define any of the structs usually found in
…		…
3781	as well as for signal and thread safety in C<ev_async> watchers.	4115	as well as for signal and thread safety in C<ev_async> watchers.
3782		4116
3783	In the absence of this define, libev will use C<sig_atomic_t volatile>	4117	In the absence of this define, libev will use C<sig_atomic_t volatile>
3784	(from F<signal.h>), which is usually good enough on most platforms.	4118	(from F<signal.h>), which is usually good enough on most platforms.
3785		4119
3786	=item EV_H	4120	=item EV_H (h)
3787		4121
3788	The name of the F<ev.h> header file used to include it. The default if	4122	The name of the F<ev.h> header file used to include it. The default if
3789	undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be	4123	undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be
3790	used to virtually rename the F<ev.h> header file in case of conflicts.	4124	used to virtually rename the F<ev.h> header file in case of conflicts.
3791		4125
3792	=item EV_CONFIG_H	4126	=item EV_CONFIG_H (h)
3793		4127
3794	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override	4128	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override
3795	F<ev.c>'s idea of where to find the F<config.h> file, similarly to	4129	F<ev.c>'s idea of where to find the F<config.h> file, similarly to
3796	C<EV_H>, above.	4130	C<EV_H>, above.
3797		4131
3798	=item EV_EVENT_H	4132	=item EV_EVENT_H (h)
3799		4133
3800	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea	4134	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea
3801	of how the F<event.h> header can be found, the default is C<"event.h">.	4135	of how the F<event.h> header can be found, the default is C<"event.h">.
3802		4136
3803	=item EV_PROTOTYPES	4137	=item EV_PROTOTYPES (h)
3804		4138
3805	If defined to be C<0>, then F<ev.h> will not define any function	4139	If defined to be C<0>, then F<ev.h> will not define any function
3806	prototypes, but still define all the structs and other symbols. This is	4140	prototypes, but still define all the structs and other symbols. This is
3807	occasionally useful if you want to provide your own wrapper functions	4141	occasionally useful if you want to provide your own wrapper functions
3808	around libev functions.	4142	around libev functions.
…		…
3830	fine.	4164	fine.
3831		4165
3832	If your embedding application does not need any priorities, defining these	4166	If your embedding application does not need any priorities, defining these
3833	both to C<0> will save some memory and CPU.	4167	both to C<0> will save some memory and CPU.
3834		4168
3835	=item EV_PERIODIC_ENABLE	4169	=item EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE,
		4170	EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE,
		4171	EV_ASYNC_ENABLE, EV_CHILD_ENABLE.
3836		4172
3837	If undefined or defined to be C<1>, then periodic timers are supported. If	4173	If undefined or defined to be C<1> (and the platform supports it), then
3838	defined to be C<0>, then they are not. Disabling them saves a few kB of	4174	the respective watcher type is supported. If defined to be C<0>, then it
3839	code.	4175	is not. Disabling watcher types mainly saves code size.
3840		4176
3841	=item EV_IDLE_ENABLE	4177	=item EV_FEATURES
3842
3843	If undefined or defined to be C<1>, then idle watchers are supported. If
3844	defined to be C<0>, then they are not. Disabling them saves a few kB of
3845	code.
3846
3847	=item EV_EMBED_ENABLE
3848
3849	If undefined or defined to be C<1>, then embed watchers are supported. If
3850	defined to be C<0>, then they are not. Embed watchers rely on most other
3851	watcher types, which therefore must not be disabled.
3852
3853	=item EV_STAT_ENABLE
3854
3855	If undefined or defined to be C<1>, then stat watchers are supported. If
3856	defined to be C<0>, then they are not.
3857
3858	=item EV_FORK_ENABLE
3859
3860	If undefined or defined to be C<1>, then fork watchers are supported. If
3861	defined to be C<0>, then they are not.
3862
3863	=item EV_ASYNC_ENABLE
3864
3865	If undefined or defined to be C<1>, then async watchers are supported. If
3866	defined to be C<0>, then they are not.
3867
3868	=item EV_MINIMAL
3869		4178
3870	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
3871	speed (but with the full API), define this symbol to C<1>. Currently this	4180	speed (but with the full API), you can define this symbol to request
3872	is used to override some inlining decisions, saves roughly 30% code size	4181	certain subsets of functionality. The default is to enable all features
3873	on amd64. It also selects a much smaller 2-heap for timer management over	4182	that can be enabled on the platform.
3874	the default 4-heap.
3875		4183
3876	You can save even more by disabling watcher types you do not need	4184	A typical way to use this symbol is to define it to C<0> (or to a bitset
3877	and setting C<EV_MAXPRI> == C<EV_MINPRI>. Also, disabling C<assert>	4185	with some broad features you want) and then selectively re-enable
3878	(C<-DNDEBUG>) will usually reduce code size a lot.	4186	additional parts you want, for example if you want everything minimal,
		4187	but multiple event loop support, async and child watchers and the poll
		4188	backend, use this:
3879		4189
3880	Defining C<EV_MINIMAL> to C<2> will additionally reduce the core API to	4190	#define EV_FEATURES 0
3881	provide a bare-bones event library. See C<ev.h> for details on what parts	4191	#define EV_MULTIPLICITY 1
3882	of the API are still available, and do not complain if this subset changes	4192	#define EV_USE_POLL 1
3883	over time.	4193	#define EV_CHILD_ENABLE 1
		4194	#define EV_ASYNC_ENABLE 1
		4195
		4196	The actual value is a bitset, it can be a combination of the following
		4197	values:
		4198
		4199	=over 4
		4200
		4201	=item C<1> - faster/larger code
		4202
		4203	Use larger code to speed up some operations.
		4204
		4205	Currently this is used to override some inlining decisions (enlarging the
		4206	code size by roughly 30% on amd64).
		4207
		4208	When optimising for size, use of compiler flags such as C<-Os> with
		4209	gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of
		4210	assertions.
		4211
		4212	=item C<2> - faster/larger data structures
		4213
		4214	Replaces the small 2-heap for timer management by a faster 4-heap, larger
		4215	hash table sizes and so on. This will usually further increase code size
		4216	and can additionally have an effect on the size of data structures at
		4217	runtime.
		4218
		4219	=item C<4> - full API configuration
		4220
		4221	This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and
		4222	enables multiplicity (C<EV_MULTIPLICITY>=1).
		4223
		4224	=item C<8> - full API
		4225
		4226	This enables a lot of the "lesser used" API functions. See C<ev.h> for
		4227	details on which parts of the API are still available without this
		4228	feature, and do not complain if this subset changes over time.
		4229
		4230	=item C<16> - enable all optional watcher types
		4231
		4232	Enables all optional watcher types. If you want to selectively enable
		4233	only some watcher types other than I/O and timers (e.g. prepare,
		4234	embed, async, child...) you can enable them manually by defining
		4235	C<EV_watchertype_ENABLE> to C<1> instead.
		4236
		4237	=item C<32> - enable all backends
		4238
		4239	This enables all backends - without this feature, you need to enable at
		4240	least one backend manually (C<EV_USE_SELECT> is a good choice).
		4241
		4242	=item C<64> - enable OS-specific "helper" APIs
		4243
		4244	Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by
		4245	default.
		4246
		4247	=back
		4248
		4249	Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0>
		4250	reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb
		4251	code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O
		4252	watchers, timers and monotonic clock support.
		4253
		4254	With an intelligent-enough linker (gcc+binutils are intelligent enough
		4255	when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by
		4256	your program might be left out as well - a binary starting a timer and an
		4257	I/O watcher then might come out at only 5Kb.
		4258
		4259	=item EV_AVOID_STDIO
		4260
		4261	If this is set to C<1> at compiletime, then libev will avoid using stdio
		4262	functions (printf, scanf, perror etc.). This will increase the code size
		4263	somewhat, but if your program doesn't otherwise depend on stdio and your
		4264	libc allows it, this avoids linking in the stdio library which is quite
		4265	big.
		4266
		4267	Note that error messages might become less precise when this option is
		4268	enabled.
3884		4269
3885	=item EV_NSIG	4270	=item EV_NSIG
3886		4271
3887	The highest supported signal number, +1 (or, the number of	4272	The highest supported signal number, +1 (or, the number of
3888	signals): Normally, libev tries to deduce the maximum number of signals	4273	signals): Normally, libev tries to deduce the maximum number of signals
3889	automatically, but sometimes this fails, in which case it can be	4274	automatically, but sometimes this fails, in which case it can be
3890	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
3891	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
3892	statically allocates some 12-24 bytes per signal number.	4277	statically allocates some 12-24 bytes per signal number.
3893		4278
3894	=item EV_PID_HASHSIZE	4279	=item EV_PID_HASHSIZE
3895		4280
3896	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
3897	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more	4282	pid. The default size is C<16> (or C<1> with C<EV_FEATURES> disabled),
3898	than enough. If you need to manage thousands of children you might want to	4283	usually more than enough. If you need to manage thousands of children you
3899	increase this value (I<must> be a power of two).	4284	might want to increase this value (I<must> be a power of two).
3900		4285
3901	=item EV_INOTIFY_HASHSIZE	4286	=item EV_INOTIFY_HASHSIZE
3902		4287
3903	C<ev_stat> watchers use a small hash table to distribute workload by	4288	C<ev_stat> watchers use a small hash table to distribute workload by
3904	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),	4289	inotify watch id. The default size is C<16> (or C<1> with C<EV_FEATURES>
3905	usually more than enough. If you need to manage thousands of C<ev_stat>	4290	disabled), usually more than enough. If you need to manage thousands of
3906	watchers you might want to increase this value (I<must> be a power of	4291	C<ev_stat> watchers you might want to increase this value (I<must> be a
3907	two).	4292	power of two).
3908		4293
3909	=item EV_USE_4HEAP	4294	=item EV_USE_4HEAP
3910		4295
3911	Heaps are not very cache-efficient. To improve the cache-efficiency of the	4296	Heaps are not very cache-efficient. To improve the cache-efficiency of the
3912	timer and periodics heaps, libev uses a 4-heap when this symbol is defined	4297	timer and periodics heaps, libev uses a 4-heap when this symbol is defined
3913	to C<1>. The 4-heap uses more complicated (longer) code but has noticeably	4298	to C<1>. The 4-heap uses more complicated (longer) code but has noticeably
3914	faster performance with many (thousands) of watchers.	4299	faster performance with many (thousands) of watchers.
3915		4300
3916	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>	4301	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3917	(disabled).	4302	will be C<0>.
3918		4303
3919	=item EV_HEAP_CACHE_AT	4304	=item EV_HEAP_CACHE_AT
3920		4305
3921	Heaps are not very cache-efficient. To improve the cache-efficiency of the	4306	Heaps are not very cache-efficient. To improve the cache-efficiency of the
3922	timer and periodics heaps, libev can cache the timestamp (I<at>) within	4307	timer and periodics heaps, libev can cache the timestamp (I<at>) within
3923	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),	4308	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),
3924	which uses 8-12 bytes more per watcher and a few hundred bytes more code,	4309	which uses 8-12 bytes more per watcher and a few hundred bytes more code,
3925	but avoids random read accesses on heap changes. This improves performance	4310	but avoids random read accesses on heap changes. This improves performance
3926	noticeably with many (hundreds) of watchers.	4311	noticeably with many (hundreds) of watchers.
3927		4312
3928	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>	4313	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3929	(disabled).	4314	will be C<0>.
3930		4315
3931	=item EV_VERIFY	4316	=item EV_VERIFY
3932		4317
3933	Controls how much internal verification (see C<ev_loop_verify ()>) will	4318	Controls how much internal verification (see C<ev_verify ()>) will
3934	be done: If set to C<0>, no internal verification code will be compiled	4319	be done: If set to C<0>, no internal verification code will be compiled
3935	in. If set to C<1>, then verification code will be compiled in, but not	4320	in. If set to C<1>, then verification code will be compiled in, but not
3936	called. If set to C<2>, then the internal verification code will be	4321	called. If set to C<2>, then the internal verification code will be
3937	called once per loop, which can slow down libev. If set to C<3>, then the	4322	called once per loop, which can slow down libev. If set to C<3>, then the
3938	verification code will be called very frequently, which will slow down	4323	verification code will be called very frequently, which will slow down
3939	libev considerably.	4324	libev considerably.
3940		4325
3941	The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be	4326	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3942	C<0>.	4327	will be C<0>.
3943		4328
3944	=item EV_COMMON	4329	=item EV_COMMON
3945		4330
3946	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
3947	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
3948	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,
3949	though, and it must be identical each time.	4334	though, and it must be identical each time.
3950		4335
3951	For example, the perl EV module uses something like this:	4336	For example, the perl EV module uses something like this:
3952		4337
…		…
4005	file.	4390	file.
4006		4391
4007	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
4008	that everybody includes and which overrides some configure choices:	4393	that everybody includes and which overrides some configure choices:
4009		4394
4010	#define EV_MINIMAL 1	4395	#define EV_FEATURES 8
4011	#define EV_USE_POLL 0	4396	#define EV_USE_SELECT 1
4012	#define EV_MULTIPLICITY 0
4013	#define EV_PERIODIC_ENABLE 0	4397	#define EV_PREPARE_ENABLE 1
		4398	#define EV_IDLE_ENABLE 1
4014	#define EV_STAT_ENABLE 0	4399	#define EV_SIGNAL_ENABLE 1
4015	#define EV_FORK_ENABLE 0	4400	#define EV_CHILD_ENABLE 1
		4401	#define EV_USE_STDEXCEPT 0
4016	#define EV_CONFIG_H <config.h>	4402	#define EV_CONFIG_H <config.h>
4017	#define EV_MINPRI 0
4018	#define EV_MAXPRI 0
4019		4403
4020	#include "ev++.h"	4404	#include "ev++.h"
4021		4405
4022	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:
4023		4407
…		…
4154	userdata *u = ev_userdata (EV_A);	4538	userdata *u = ev_userdata (EV_A);
4155	pthread_mutex_lock (&u->lock);	4539	pthread_mutex_lock (&u->lock);
4156	}	4540	}
4157		4541
4158	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
4159	into C<ev_loop>:	4543	into C<ev_run>:
4160		4544
4161	void *	4545	void *
4162	l_run (void *thr_arg)	4546	l_run (void *thr_arg)
4163	{	4547	{
4164	struct ev_loop *loop = (struct ev_loop *)thr_arg;	4548	struct ev_loop *loop = (struct ev_loop *)thr_arg;
4165		4549
4166	l_acquire (EV_A);	4550	l_acquire (EV_A);
4167	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);	4551	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
4168	ev_loop (EV_A_ 0);	4552	ev_run (EV_A_ 0);
4169	l_release (EV_A);	4553	l_release (EV_A);
4170		4554
4171	return 0;	4555	return 0;
4172	}	4556	}
4173		4557
…		…
4225		4609
4226	=head3 COROUTINES	4610	=head3 COROUTINES
4227		4611
4228	Libev is very accommodating to coroutines ("cooperative threads"):	4612	Libev is very accommodating to coroutines ("cooperative threads"):
4229	libev fully supports nesting calls to its functions from different	4613	libev fully supports nesting calls to its functions from different
4230	coroutines (e.g. you can call C<ev_loop> on the same loop from two	4614	coroutines (e.g. you can call C<ev_run> on the same loop from two
4231	different coroutines, and switch freely between both coroutines running	4615	different coroutines, and switch freely between both coroutines running
4232	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
4233	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.
4234		4618
4235	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
4236	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
4237	they do not call any callbacks.	4621	they do not call any callbacks.
4238		4622
4239	=head2 COMPILER WARNINGS	4623	=head2 COMPILER WARNINGS
4240		4624
4241	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
…		…
4252	maintainable.	4636	maintainable.
4253		4637
4254	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
4255	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
4256	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
4257	warnings that resulted an extreme number of false positives. These have	4641	warnings that resulted in an extreme number of false positives. These have
4258	been fixed, but some people still insist on making code warn-free with	4642	been fixed, but some people still insist on making code warn-free with
4259	such buggy versions.	4643	such buggy versions.
4260		4644
4261	While libev is written to generate as few warnings as possible,	4645	While libev is written to generate as few warnings as possible,
4262	"warn-free" code is not a goal, and it is recommended not to build libev	4646	"warn-free" code is not a goal, and it is recommended not to build libev
…		…
4298	I suggest using suppression lists.	4682	I suggest using suppression lists.
4299		4683
4300		4684
4301	=head1 PORTABILITY NOTES	4685	=head1 PORTABILITY NOTES
4302		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
4303	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS	4773	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
		4774
		4775	=head3 General issues
4304		4776
4305	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
4306	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
4307	model. Libev still offers limited functionality on this platform in	4779	model. Libev still offers limited functionality on this platform in
4308	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
4309	descriptors. This only applies when using Win32 natively, not when using	4781	descriptors. This only applies when using Win32 natively, not when using
4310	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.
4311		4785
4312	Lifting these limitations would basically require the full	4786	Lifting these limitations would basically require the full
4313	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,
4314	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
4315	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).
4316		4790
4317	There is no supported compilation method available on windows except	4791	There is no supported compilation method available on windows except
4318	embedding it into other applications.	4792	embedding it into other applications.
4319		4793
4320	Sensible signal handling is officially unsupported by Microsoft - libev	4794	Sensible signal handling is officially unsupported by Microsoft - libev
…		…
4348	you do I<not> compile the F<ev.c> or any other embedded source files!):	4822	you do I<not> compile the F<ev.c> or any other embedded source files!):
4349		4823
4350	#include "evwrap.h"	4824	#include "evwrap.h"
4351	#include "ev.c"	4825	#include "ev.c"
4352		4826
4353	=over 4
4354
4355	=item The winsocket select function	4827	=head3 The winsocket C<select> function
4356		4828
4357	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
4358	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
4359	also extremely buggy). This makes select very inefficient, and also	4831	also extremely buggy). This makes select very inefficient, and also
4360	requires a mapping from file descriptors to socket handles (the Microsoft	4832	requires a mapping from file descriptors to socket handles (the Microsoft
…		…
4369	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */	4841	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
4370		4842
4371	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
4372	complexity in the O(n²) range when using win32.	4844	complexity in the O(n²) range when using win32.
4373		4845
4374	=item Limited number of file descriptors	4846	=head3 Limited number of file descriptors
4375		4847
4376	Windows has numerous arbitrary (and low) limits on things.	4848	Windows has numerous arbitrary (and low) limits on things.
4377		4849
4378	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
4379	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
…		…
4394	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
4395	(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,
4396	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
4397	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.
4398		4870
4399	=back
4400
4401	=head2 PORTABILITY REQUIREMENTS	4871	=head2 PORTABILITY REQUIREMENTS
4402		4872
4403	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
4404	backend-specific APIs, libev relies on a few additional extensions:	4874	backend-specific APIs, libev relies on a few additional extensions:
4405		4875
…		…
4411	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
4412	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
4413	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
4414	callback: The watcher callbacks have different type signatures, but libev	4884	callback: The watcher callbacks have different type signatures, but libev
4415	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.
4416		4891
4417	=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
4418		4893
4419	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
4420	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
…		…
4443	watchers.	4918	watchers.
4444		4919
4445	=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
4446		4921
4447	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
4448	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
4449	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
4450	implementations implementing IEEE 754, which is basically all existing	4926	implementations using IEEE 754, which is basically all existing ones. With
4451	ones. With IEEE 754 doubles, you get microsecond accuracy until at least	4927	IEEE 754 doubles, you get microsecond accuracy until at least 2200.
4452	2200.
4453		4928
4454	=back	4929	=back
4455		4930
4456	If you know of other additional requirements drop me a note.	4931	If you know of other additional requirements drop me a note.
4457		4932
…		…
4525	involves iterating over all running async watchers or all signal numbers.	5000	involves iterating over all running async watchers or all signal numbers.
4526		5001
4527	=back	5002	=back
4528		5003
4529		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
4530	=head1 GLOSSARY	5065	=head1 GLOSSARY
4531		5066
4532	=over 4	5067	=over 4
4533		5068
4534	=item active	5069	=item active
4535		5070
4536	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.
4537	an event loop) but not yet stopped (disassociated from the event loop).	5072	See L<WATCHER STATES> for details.
4538		5073
4539	=item application	5074	=item application
4540		5075
4541	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.
4542		5081
4543	=item callback	5082	=item callback
4544		5083
4545	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
4546	detected. Callbacks are being passed the event loop, the watcher that	5085	detected. Callbacks are being passed the event loop, the watcher that
4547	received the event, and the actual event bitset.	5086	received the event, and the actual event bitset.
4548		5087
4549	=item callback invocation	5088	=item callback/watcher invocation
4550		5089
4551	The act of calling the callback associated with a watcher.	5090	The act of calling the callback associated with a watcher.
4552		5091
4553	=item event	5092	=item event
4554		5093
4555	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
4556	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
4557	any other events happening anymore.	5096	any other events happening anymore.
4558		5097
4559	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
4560	C<EV_TIMEOUT>).	5099	C<EV_TIMER>).
4561		5100
4562	=item event library	5101	=item event library
4563		5102
4564	A software package implementing an event model and loop.	5103	A software package implementing an event model and loop.
4565		5104
…		…
4573	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
4574	watchers and events.	5113	watchers and events.
4575		5114
4576	=item pending	5115	=item pending
4577		5116
4578	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
4579	and stops being pending as soon as the watcher will be invoked or its	5118	detected. See L<WATCHER STATES> for details.
4580	pending status is explicitly cleared by the application.
4581
4582	A watcher can be pending, but not active. Stopping a watcher also clears
4583	its pending status.
4584		5119
4585	=item real time	5120	=item real time
4586		5121
4587	The physical time that is observed. It is apparently strictly monotonic :)	5122	The physical time that is observed. It is apparently strictly monotonic :)
4588		5123
…		…
4595	=item watcher	5130	=item watcher
4596		5131
4597	A data structure that describes interest in certain events. Watchers need	5132	A data structure that describes interest in certain events. Watchers need
4598	to be started (attached to an event loop) before they can receive events.	5133	to be started (attached to an event loop) before they can receive events.
4599		5134
4600	=item watcher invocation
4601
4602	The act of calling the callback associated with a watcher.
4603
4604	=back	5135	=back
4605		5136
4606	=head1 AUTHOR	5137	=head1 AUTHOR
4607		5138
4608	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.
4609		5141

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