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Revision 1.265 by root, Wed Aug 26 17:11:42 2009 UTC vs.
Revision 1.349 by root, Mon Jan 10 01:58:55 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
…		…
118	Libev is very configurable. In this manual the default (and most common)	126	Libev is very configurable. In this manual the default (and most common)
119	configuration will be described, which supports multiple event loops. For	127	configuration will be described, which supports multiple event loops. For
120	more info about various configuration options please have a look at	128	more info about various configuration options please have a look at
121	B<EMBED> section in this manual. If libev was configured without support	129	B<EMBED> section in this manual. If libev was configured without support
122	for multiple event loops, then all functions taking an initial argument of	130	for multiple event loops, then all functions taking an initial argument of
123	name C<loop> (which is always of type C<ev_loop *>) will not have	131	name C<loop> (which is always of type C<struct ev_loop *>) will not have
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	It's 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_NOSIGNALFD>	424	=item C<EVFLAG_SIGNALFD>
376		425
377	When this flag is specified, then libev will not 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 is	427	I<signalfd> API for its C<ev_signal> (and C<ev_child>) watchers. This API
379	probably only useful to work around any bugs in libev. Consequently, this	428	delivers signals synchronously, which makes it both faster and might make
380	flag might go away once the signalfd functionality is considered stable,	429	it possible to get the queued signal data. It can also simplify signal
381	so it's useful mostly in environment variables and not in program code.	430	handling with threads, as long as you properly block signals in your
		431	threads that are not interested in handling them.
		432
		433	Signalfd will not be used by default as this changes your signal mask, and
		434	there are a lot of shoddy libraries and programs (glib's threadpool for
		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.
382		448
383	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	449	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
384		450
385	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
386	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,
…		…
411	This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and	477	This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and
412	C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>.	478	C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>.
413		479
414	=item C<EVBACKEND_EPOLL> (value 4, Linux)	480	=item C<EVBACKEND_EPOLL> (value 4, Linux)
415		481
		482	Use the linux-specific epoll(7) interface (for both pre- and post-2.6.9
		483	kernels).
		484
416	For few fds, this backend is a bit little slower than poll and select,	485	For few fds, this backend is a bit little slower than poll and select,
417	but it scales phenomenally better. While poll and select usually scale	486	but it scales phenomenally better. While poll and select usually scale
418	like O(total_fds) where n is the total number of fds (or the highest fd),	487	like O(total_fds) where n is the total number of fds (or the highest fd),
419	epoll scales either O(1) or O(active_fds).	488	epoll scales either O(1) or O(active_fds).
420		489
421	The epoll mechanism deserves honorable mention as the most misdesigned	490	The epoll mechanism deserves honorable mention as the most misdesigned
422	of the more advanced event mechanisms: mere annoyances include silently	491	of the more advanced event mechanisms: mere annoyances include silently
423	dropping file descriptors, requiring a system call per change per file	492	dropping file descriptors, requiring a system call per change per file
424	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
425	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
426	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
427	take considerable time (one syscall per file descriptor) and is of course	498	set, which can take considerable time (one syscall per file descriptor)
428	hard to detect.	499	and is of course hard to detect.
429		500
430	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
431	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
432	I<different> file descriptors (even already closed ones, so one cannot	503	I<different> file descriptors (even already closed ones, so one cannot
433	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
434	on SMP systems). Libev tries to counter these spurious notifications by	505	on SMP systems). Libev tries to counter these spurious notifications by
435	employing an additional generation counter and comparing that against the	506	employing an additional generation counter and comparing that against the
436	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.
437		512
438	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
439	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
440	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
441	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
…		…
530		605
531	Try all backends (even potentially broken ones that wouldn't be tried	606	Try all backends (even potentially broken ones that wouldn't be tried
532	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as	607	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as
533	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.	608	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.
534		609
535	It is definitely not recommended to use this flag.	610	It is definitely not recommended to use this flag, use whatever
		611	C<ev_recommended_backends ()> returns, or simply do not specify a backend
		612	at all.
		613
		614	=item C<EVBACKEND_MASK>
		615
		616	Not a backend at all, but a mask to select all backend bits from a
		617	C<flags> value, in case you want to mask out any backends from a flags
		618	value (e.g. when modifying the C<LIBEV_FLAGS> environment variable).
536		619
537	=back	620	=back
538		621
539	If one or more of the backend flags are or'ed into the flags value,	622	If one or more of the backend flags are or'ed into the flags value,
540	then only these backends will be tried (in the reverse order as listed	623	then only these backends will be tried (in the reverse order as listed
541	here). If none are specified, all backends in C<ev_recommended_backends	624	here). If none are specified, all backends in C<ev_recommended_backends
542	()> will be tried.	625	()> will be tried.
543		626
544	Example: This is the most typical usage.
545
546	if (!ev_default_loop (0))
547	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
548
549	Example: Restrict libev to the select and poll backends, and do not allow
550	environment settings to be taken into account:
551
552	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
553
554	Example: Use whatever libev has to offer, but make sure that kqueue is
555	used if available (warning, breaks stuff, best use only with your own
556	private event loop and only if you know the OS supports your types of
557	fds):
558
559	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
560
561	=item struct ev_loop *ev_loop_new (unsigned int flags)
562
563	Similar to C<ev_default_loop>, but always creates a new event loop that is
564	always distinct from the default loop. Unlike the default loop, it cannot
565	handle signal and child watchers, and attempts to do so will be greeted by
566	undefined behaviour (or a failed assertion if assertions are enabled).
567
568	Note that this function I<is> thread-safe, and the recommended way to use
569	libev with threads is indeed to create one loop per thread, and using the
570	default loop in the "main" or "initial" thread.
571
572	Example: Try to create a event loop that uses epoll and nothing else.	627	Example: Try to create a event loop that uses epoll and nothing else.
573		628
574	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	629	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
575	if (!epoller)	630	if (!epoller)
576	fatal ("no epoll found here, maybe it hides under your chair");	631	fatal ("no epoll found here, maybe it hides under your chair");
577		632
		633	Example: Use whatever libev has to offer, but make sure that kqueue is
		634	used if available.
		635
		636	struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE);
		637
578	=item ev_default_destroy ()	638	=item ev_loop_destroy (loop)
579		639
580	Destroys the default loop again (frees all memory and kernel state	640	Destroys an event loop object (frees all memory and kernel state
581	etc.). None of the active event watchers will be stopped in the normal	641	etc.). None of the active event watchers will be stopped in the normal
582	sense, so e.g. C<ev_is_active> might still return true. It is your	642	sense, so e.g. C<ev_is_active> might still return true. It is your
583	responsibility to either stop all watchers cleanly yourself I<before>	643	responsibility to either stop all watchers cleanly yourself I<before>
584	calling this function, or cope with the fact afterwards (which is usually	644	calling this function, or cope with the fact afterwards (which is usually
585	the easiest thing, you can just ignore the watchers and/or C<free ()> them	645	the easiest thing, you can just ignore the watchers and/or C<free ()> them
…		…
587		647
588	Note that certain global state, such as signal state (and installed signal	648	Note that certain global state, such as signal state (and installed signal
589	handlers), will not be freed by this function, and related watchers (such	649	handlers), will not be freed by this function, and related watchers (such
590	as signal and child watchers) would need to be stopped manually.	650	as signal and child watchers) would need to be stopped manually.
591		651
592	In general it is not advisable to call this function except in the	652	This function is normally used on loop objects allocated by
593	rare occasion where you really need to free e.g. the signal handling	653	C<ev_loop_new>, but it can also be used on the default loop returned by
		654	C<ev_default_loop>, in which case it is not thread-safe.
		655
		656	Note that it is not advisable to call this function on the default loop
		657	except in the rare occasion where you really need to free its resources.
594	pipe fds. If you need dynamically allocated loops it is better to use	658	If you need dynamically allocated loops it is better to use C<ev_loop_new>
595	C<ev_loop_new> and C<ev_loop_destroy>).	659	and C<ev_loop_destroy>.
596		660
597	=item ev_loop_destroy (loop)	661	=item ev_loop_fork (loop)
598		662
599	Like C<ev_default_destroy>, but destroys an event loop created by an
600	earlier call to C<ev_loop_new>.
601
602	=item ev_default_fork ()
603
604	This function sets a flag that causes subsequent C<ev_loop> iterations	663	This function sets a flag that causes subsequent C<ev_run> iterations to
605	to reinitialise the kernel state for backends that have one. Despite the	664	reinitialise the kernel state for backends that have one. Despite the
606	name, you can call it anytime, but it makes most sense after forking, in	665	name, you can call it anytime, but it makes most sense after forking, in
607	the child process (or both child and parent, but that again makes little	666	the child process. You I<must> call it (or use C<EVFLAG_FORKCHECK>) in the
608	sense). You I<must> call it in the child before using any of the libev	667	child before resuming or calling C<ev_run>.
609	functions, and it will only take effect at the next C<ev_loop> iteration.	668
		669	Again, you I<have> to call it on I<any> loop that you want to re-use after
		670	a fork, I<even if you do not plan to use the loop in the parent>. This is
		671	because some kernel interfaces *cough* I<kqueue> *cough* do funny things
		672	during fork.
610		673
611	On the other hand, you only need to call this function in the child	674	On the other hand, you only need to call this function in the child
612	process if and only if you want to use the event library in the child. If	675	process if and only if you want to use the event loop in the child. If
613	you just fork+exec, you don't have to call it at all.	676	you just fork+exec or create a new loop in the child, you don't have to
		677	call it at all (in fact, C<epoll> is so badly broken that it makes a
		678	difference, but libev will usually detect this case on its own and do a
		679	costly reset of the backend).
614		680
615	The function itself is quite fast and it's usually not a problem to call	681	The function itself is quite fast and it's usually not a problem to call
616	it just in case after a fork. To make this easy, the function will fit in	682	it just in case after a fork.
617	quite nicely into a call to C<pthread_atfork>:
618		683
		684	Example: Automate calling C<ev_loop_fork> on the default loop when
		685	using pthreads.
		686
		687	static void
		688	post_fork_child (void)
		689	{
		690	ev_loop_fork (EV_DEFAULT);
		691	}
		692
		693	...
619	pthread_atfork (0, 0, ev_default_fork);	694	pthread_atfork (0, 0, post_fork_child);
620
621	=item ev_loop_fork (loop)
622
623	Like C<ev_default_fork>, but acts on an event loop created by
624	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
625	after fork that you want to re-use in the child, and how you do this is
626	entirely your own problem.
627		695
628	=item int ev_is_default_loop (loop)	696	=item int ev_is_default_loop (loop)
629		697
630	Returns true when the given loop is, in fact, the default loop, and false	698	Returns true when the given loop is, in fact, the default loop, and false
631	otherwise.	699	otherwise.
632		700
633	=item unsigned int ev_loop_count (loop)	701	=item unsigned int ev_iteration (loop)
634		702
635	Returns the count of loop iterations for the loop, which is identical to	703	Returns the current iteration count for the event loop, which is identical
636	the number of times libev did poll for new events. It starts at C<0> and	704	to the number of times libev did poll for new events. It starts at C<0>
637	happily wraps around with enough iterations.	705	and happily wraps around with enough iterations.
638		706
639	This value can sometimes be useful as a generation counter of sorts (it	707	This value can sometimes be useful as a generation counter of sorts (it
640	"ticks" the number of loop iterations), as it roughly corresponds with	708	"ticks" the number of loop iterations), as it roughly corresponds with
641	C<ev_prepare> and C<ev_check> calls.	709	C<ev_prepare> and C<ev_check> calls - and is incremented between the
		710	prepare and check phases.
642		711
643	=item unsigned int ev_loop_depth (loop)	712	=item unsigned int ev_depth (loop)
644		713
645	Returns the number of times C<ev_loop> was entered minus the number of	714	Returns the number of times C<ev_run> was entered minus the number of
646	times C<ev_loop> was exited, in other words, the recursion depth.	715	times C<ev_run> was exited normally, in other words, the recursion depth.
647		716
648	Outside C<ev_loop>, this number is zero. In a callback, this number is	717	Outside C<ev_run>, this number is zero. In a callback, this number is
649	C<1>, unless C<ev_loop> was invoked recursively (or from another thread),	718	C<1>, unless C<ev_run> was invoked recursively (or from another thread),
650	in which case it is higher.	719	in which case it is higher.
651		720
652	Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread	721	Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread,
653	etc.), doesn't count as exit.	722	throwing an exception etc.), doesn't count as "exit" - consider this
		723	as a hint to avoid such ungentleman-like behaviour unless it's really
		724	convenient, in which case it is fully supported.
654		725
655	=item unsigned int ev_backend (loop)	726	=item unsigned int ev_backend (loop)
656		727
657	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	728	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
658	use.	729	use.
…		…
667		738
668	=item ev_now_update (loop)	739	=item ev_now_update (loop)
669		740
670	Establishes the current time by querying the kernel, updating the time	741	Establishes the current time by querying the kernel, updating the time
671	returned by C<ev_now ()> in the progress. This is a costly operation and	742	returned by C<ev_now ()> in the progress. This is a costly operation and
672	is usually done automatically within C<ev_loop ()>.	743	is usually done automatically within C<ev_run ()>.
673		744
674	This function is rarely useful, but when some event callback runs for a	745	This function is rarely useful, but when some event callback runs for a
675	very long time without entering the event loop, updating libev's idea of	746	very long time without entering the event loop, updating libev's idea of
676	the current time is a good idea.	747	the current time is a good idea.
677		748
…		…
679		750
680	=item ev_suspend (loop)	751	=item ev_suspend (loop)
681		752
682	=item ev_resume (loop)	753	=item ev_resume (loop)
683		754
684	These two functions suspend and resume a loop, for use when the loop is	755	These two functions suspend and resume an event loop, for use when the
685	not used for a while and timeouts should not be processed.	756	loop is not used for a while and timeouts should not be processed.
686		757
687	A typical use case would be an interactive program such as a game: When	758	A typical use case would be an interactive program such as a game: When
688	the user presses C<^Z> to suspend the game and resumes it an hour later it	759	the user presses C<^Z> to suspend the game and resumes it an hour later it
689	would be best to handle timeouts as if no time had actually passed while	760	would be best to handle timeouts as if no time had actually passed while
690	the program was suspended. This can be achieved by calling C<ev_suspend>	761	the program was suspended. This can be achieved by calling C<ev_suspend>
…		…
692	C<ev_resume> directly afterwards to resume timer processing.	763	C<ev_resume> directly afterwards to resume timer processing.
693		764
694	Effectively, all C<ev_timer> watchers will be delayed by the time spend	765	Effectively, all C<ev_timer> watchers will be delayed by the time spend
695	between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers	766	between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers
696	will be rescheduled (that is, they will lose any events that would have	767	will be rescheduled (that is, they will lose any events that would have
697	occured while suspended).	768	occurred while suspended).
698		769
699	After calling C<ev_suspend> you B<must not> call I<any> function on the	770	After calling C<ev_suspend> you B<must not> call I<any> function on the
700	given loop other than C<ev_resume>, and you B<must not> call C<ev_resume>	771	given loop other than C<ev_resume>, and you B<must not> call C<ev_resume>
701	without a previous call to C<ev_suspend>.	772	without a previous call to C<ev_suspend>.
702		773
703	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the	774	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the
704	event loop time (see C<ev_now_update>).	775	event loop time (see C<ev_now_update>).
705		776
706	=item ev_loop (loop, int flags)	777	=item ev_run (loop, int flags)
707		778
708	Finally, this is it, the event handler. This function usually is called	779	Finally, this is it, the event handler. This function usually is called
709	after you initialised all your watchers and you want to start handling	780	after you have initialised all your watchers and you want to start
710	events.	781	handling events. It will ask the operating system for any new events, call
		782	the watcher callbacks, an then repeat the whole process indefinitely: This
		783	is why event loops are called I<loops>.
711		784
712	If the flags argument is specified as C<0>, it will not return until	785	If the flags argument is specified as C<0>, it will keep handling events
713	either no event watchers are active anymore or C<ev_unloop> was called.	786	until either no event watchers are active anymore or C<ev_break> was
		787	called.
714		788
715	Please note that an explicit C<ev_unloop> is usually better than	789	Please note that an explicit C<ev_break> is usually better than
716	relying on all watchers to be stopped when deciding when a program has	790	relying on all watchers to be stopped when deciding when a program has
717	finished (especially in interactive programs), but having a program	791	finished (especially in interactive programs), but having a program
718	that automatically loops as long as it has to and no longer by virtue	792	that automatically loops as long as it has to and no longer by virtue
719	of relying on its watchers stopping correctly, that is truly a thing of	793	of relying on its watchers stopping correctly, that is truly a thing of
720	beauty.	794	beauty.
721		795
		796	This function is also I<mostly> exception-safe - you can break out of
		797	a C<ev_run> call by calling C<longjmp> in a callback, throwing a C++
		798	exception and so on. This does not decrement the C<ev_depth> value, nor
		799	will it clear any outstanding C<EVBREAK_ONE> breaks.
		800
722	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle	801	A flags value of C<EVRUN_NOWAIT> will look for new events, will handle
723	those events and any already outstanding ones, but will not block your	802	those events and any already outstanding ones, but will not wait and
724	process in case there are no events and will return after one iteration of	803	block your process in case there are no events and will return after one
725	the loop.	804	iteration of the loop. This is sometimes useful to poll and handle new
		805	events while doing lengthy calculations, to keep the program responsive.
726		806
727	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if	807	A flags value of C<EVRUN_ONCE> will look for new events (waiting if
728	necessary) and will handle those and any already outstanding ones. It	808	necessary) and will handle those and any already outstanding ones. It
729	will block your process until at least one new event arrives (which could	809	will block your process until at least one new event arrives (which could
730	be an event internal to libev itself, so there is no guarantee that a	810	be an event internal to libev itself, so there is no guarantee that a
731	user-registered callback will be called), and will return after one	811	user-registered callback will be called), and will return after one
732	iteration of the loop.	812	iteration of the loop.
733		813
734	This is useful if you are waiting for some external event in conjunction	814	This is useful if you are waiting for some external event in conjunction
735	with something not expressible using other libev watchers (i.e. "roll your	815	with something not expressible using other libev watchers (i.e. "roll your
736	own C<ev_loop>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is	816	own C<ev_run>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is
737	usually a better approach for this kind of thing.	817	usually a better approach for this kind of thing.
738		818
739	Here are the gory details of what C<ev_loop> does:	819	Here are the gory details of what C<ev_run> does:
740		820
		821	- Increment loop depth.
		822	- Reset the ev_break status.
741	- Before the first iteration, call any pending watchers.	823	- Before the first iteration, call any pending watchers.
		824	LOOP:
742	* If EVFLAG_FORKCHECK was used, check for a fork.	825	- If EVFLAG_FORKCHECK was used, check for a fork.
743	- If a fork was detected (by any means), queue and call all fork watchers.	826	- If a fork was detected (by any means), queue and call all fork watchers.
744	- Queue and call all prepare watchers.	827	- Queue and call all prepare watchers.
		828	- If ev_break was called, goto FINISH.
745	- If we have been forked, detach and recreate the kernel state	829	- If we have been forked, detach and recreate the kernel state
746	as to not disturb the other process.	830	as to not disturb the other process.
747	- Update the kernel state with all outstanding changes.	831	- Update the kernel state with all outstanding changes.
748	- Update the "event loop time" (ev_now ()).	832	- Update the "event loop time" (ev_now ()).
749	- Calculate for how long to sleep or block, if at all	833	- Calculate for how long to sleep or block, if at all
750	(active idle watchers, EVLOOP_NONBLOCK or not having	834	(active idle watchers, EVRUN_NOWAIT or not having
751	any active watchers at all will result in not sleeping).	835	any active watchers at all will result in not sleeping).
752	- Sleep if the I/O and timer collect interval say so.	836	- Sleep if the I/O and timer collect interval say so.
		837	- Increment loop iteration counter.
753	- Block the process, waiting for any events.	838	- Block the process, waiting for any events.
754	- Queue all outstanding I/O (fd) events.	839	- Queue all outstanding I/O (fd) events.
755	- Update the "event loop time" (ev_now ()), and do time jump adjustments.	840	- Update the "event loop time" (ev_now ()), and do time jump adjustments.
756	- Queue all expired timers.	841	- Queue all expired timers.
757	- Queue all expired periodics.	842	- Queue all expired periodics.
758	- Unless any events are pending now, queue all idle watchers.	843	- Queue all idle watchers with priority higher than that of pending events.
759	- Queue all check watchers.	844	- Queue all check watchers.
760	- Call all queued watchers in reverse order (i.e. check watchers first).	845	- Call all queued watchers in reverse order (i.e. check watchers first).
761	Signals and child watchers are implemented as I/O watchers, and will	846	Signals and child watchers are implemented as I/O watchers, and will
762	be handled here by queueing them when their watcher gets executed.	847	be handled here by queueing them when their watcher gets executed.
763	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	848	- If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT
764	were used, or there are no active watchers, return, otherwise	849	were used, or there are no active watchers, goto FINISH, otherwise
765	continue with step *.	850	continue with step LOOP.
		851	FINISH:
		852	- Reset the ev_break status iff it was EVBREAK_ONE.
		853	- Decrement the loop depth.
		854	- Return.
766		855
767	Example: Queue some jobs and then loop until no events are outstanding	856	Example: Queue some jobs and then loop until no events are outstanding
768	anymore.	857	anymore.
769		858
770	... queue jobs here, make sure they register event watchers as long	859	... queue jobs here, make sure they register event watchers as long
771	... as they still have work to do (even an idle watcher will do..)	860	... as they still have work to do (even an idle watcher will do..)
772	ev_loop (my_loop, 0);	861	ev_run (my_loop, 0);
773	... jobs done or somebody called unloop. yeah!	862	... jobs done or somebody called unloop. yeah!
774		863
775	=item ev_unloop (loop, how)	864	=item ev_break (loop, how)
776		865
777	Can be used to make a call to C<ev_loop> return early (but only after it	866	Can be used to make a call to C<ev_run> return early (but only after it
778	has processed all outstanding events). The C<how> argument must be either	867	has processed all outstanding events). The C<how> argument must be either
779	C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or	868	C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or
780	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.	869	C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return.
781		870
782	This "unloop state" will be cleared when entering C<ev_loop> again.	871	This "break state" will be cleared on the next call to C<ev_run>.
783		872
784	It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls.	873	It is safe to call C<ev_break> from outside any C<ev_run> calls, too, in
		874	which case it will have no effect.
785		875
786	=item ev_ref (loop)	876	=item ev_ref (loop)
787		877
788	=item ev_unref (loop)	878	=item ev_unref (loop)
789		879
790	Ref/unref can be used to add or remove a reference count on the event	880	Ref/unref can be used to add or remove a reference count on the event
791	loop: Every watcher keeps one reference, and as long as the reference	881	loop: Every watcher keeps one reference, and as long as the reference
792	count is nonzero, C<ev_loop> will not return on its own.	882	count is nonzero, C<ev_run> will not return on its own.
793		883
794	If you have a watcher you never unregister that should not keep C<ev_loop>	884	This is useful when you have a watcher that you never intend to
795	from returning, call ev_unref() after starting, and ev_ref() before	885	unregister, but that nevertheless should not keep C<ev_run> from
		886	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>
796	stopping it.	887	before stopping it.
797		888
798	As an example, libev itself uses this for its internal signal pipe: It	889	As an example, libev itself uses this for its internal signal pipe: It
799	is not visible to the libev user and should not keep C<ev_loop> from	890	is not visible to the libev user and should not keep C<ev_run> from
800	exiting if no event watchers registered by it are active. It is also an	891	exiting if no event watchers registered by it are active. It is also an
801	excellent way to do this for generic recurring timers or from within	892	excellent way to do this for generic recurring timers or from within
802	third-party libraries. Just remember to I<unref after start> and I<ref	893	third-party libraries. Just remember to I<unref after start> and I<ref
803	before stop> (but only if the watcher wasn't active before, or was active	894	before stop> (but only if the watcher wasn't active before, or was active
804	before, respectively. Note also that libev might stop watchers itself	895	before, respectively. Note also that libev might stop watchers itself
805	(e.g. non-repeating timers) in which case you have to C<ev_ref>	896	(e.g. non-repeating timers) in which case you have to C<ev_ref>
806	in the callback).	897	in the callback).
807		898
808	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	899	Example: Create a signal watcher, but keep it from keeping C<ev_run>
809	running when nothing else is active.	900	running when nothing else is active.
810		901
811	ev_signal exitsig;	902	ev_signal exitsig;
812	ev_signal_init (&exitsig, sig_cb, SIGINT);	903	ev_signal_init (&exitsig, sig_cb, SIGINT);
813	ev_signal_start (loop, &exitsig);	904	ev_signal_start (loop, &exitsig);
814	evf_unref (loop);	905	ev_unref (loop);
815		906
816	Example: For some weird reason, unregister the above signal handler again.	907	Example: For some weird reason, unregister the above signal handler again.
817		908
818	ev_ref (loop);	909	ev_ref (loop);
819	ev_signal_stop (loop, &exitsig);	910	ev_signal_stop (loop, &exitsig);
…		…
858	usually doesn't make much sense to set it to a lower value than C<0.01>,	949	usually doesn't make much sense to set it to a lower value than C<0.01>,
859	as this approaches the timing granularity of most systems. Note that if	950	as this approaches the timing granularity of most systems. Note that if
860	you do transactions with the outside world and you can't increase the	951	you do transactions with the outside world and you can't increase the
861	parallelity, then this setting will limit your transaction rate (if you	952	parallelity, then this setting will limit your transaction rate (if you
862	need to poll once per transaction and the I/O collect interval is 0.01,	953	need to poll once per transaction and the I/O collect interval is 0.01,
863	then you can't do more than 100 transations per second).	954	then you can't do more than 100 transactions per second).
864		955
865	Setting the I<timeout collect interval> can improve the opportunity for	956	Setting the I<timeout collect interval> can improve the opportunity for
866	saving power, as the program will "bundle" timer callback invocations that	957	saving power, as the program will "bundle" timer callback invocations that
867	are "near" in time together, by delaying some, thus reducing the number of	958	are "near" in time together, by delaying some, thus reducing the number of
868	times the process sleeps and wakes up again. Another useful technique to	959	times the process sleeps and wakes up again. Another useful technique to
…		…
876	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);	967	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);
877		968
878	=item ev_invoke_pending (loop)	969	=item ev_invoke_pending (loop)
879		970
880	This call will simply invoke all pending watchers while resetting their	971	This call will simply invoke all pending watchers while resetting their
881	pending state. Normally, C<ev_loop> does this automatically when required,	972	pending state. Normally, C<ev_run> does this automatically when required,
882	but when overriding the invoke callback this call comes handy.	973	but when overriding the invoke callback this call comes handy. This
		974	function can be invoked from a watcher - this can be useful for example
		975	when you want to do some lengthy calculation and want to pass further
		976	event handling to another thread (you still have to make sure only one
		977	thread executes within C<ev_invoke_pending> or C<ev_run> of course).
883		978
884	=item int ev_pending_count (loop)	979	=item int ev_pending_count (loop)
885		980
886	Returns the number of pending watchers - zero indicates that no watchers	981	Returns the number of pending watchers - zero indicates that no watchers
887	are pending.	982	are pending.
888		983
889	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))	984	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))
890		985
891	This overrides the invoke pending functionality of the loop: Instead of	986	This overrides the invoke pending functionality of the loop: Instead of
892	invoking all pending watchers when there are any, C<ev_loop> will call	987	invoking all pending watchers when there are any, C<ev_run> will call
893	this callback instead. This is useful, for example, when you want to	988	this callback instead. This is useful, for example, when you want to
894	invoke the actual watchers inside another context (another thread etc.).	989	invoke the actual watchers inside another context (another thread etc.).
895		990
896	If you want to reset the callback, use C<ev_invoke_pending> as new	991	If you want to reset the callback, use C<ev_invoke_pending> as new
897	callback.	992	callback.
…		…
900		995
901	Sometimes you want to share the same loop between multiple threads. This	996	Sometimes you want to share the same loop between multiple threads. This
902	can be done relatively simply by putting mutex_lock/unlock calls around	997	can be done relatively simply by putting mutex_lock/unlock calls around
903	each call to a libev function.	998	each call to a libev function.
904		999
905	However, C<ev_loop> can run an indefinite time, so it is not feasible to	1000	However, C<ev_run> can run an indefinite time, so it is not feasible
906	wait for it to return. One way around this is to wake up the loop via	1001	to wait for it to return. One way around this is to wake up the event
907	C<ev_unloop> and C<av_async_send>, another way is to set these I<release>	1002	loop via C<ev_break> and C<av_async_send>, another way is to set these
908	and I<acquire> callbacks on the loop.	1003	I<release> and I<acquire> callbacks on the loop.
909		1004
910	When set, then C<release> will be called just before the thread is	1005	When set, then C<release> will be called just before the thread is
911	suspended waiting for new events, and C<acquire> is called just	1006	suspended waiting for new events, and C<acquire> is called just
912	afterwards.	1007	afterwards.
913		1008
…		…
916		1011
917	While event loop modifications are allowed between invocations of	1012	While event loop modifications are allowed between invocations of
918	C<release> and C<acquire> (that's their only purpose after all), no	1013	C<release> and C<acquire> (that's their only purpose after all), no
919	modifications done will affect the event loop, i.e. adding watchers will	1014	modifications done will affect the event loop, i.e. adding watchers will
920	have no effect on the set of file descriptors being watched, or the time	1015	have no effect on the set of file descriptors being watched, or the time
921	waited. USe an C<ev_async> watcher to wake up C<ev_loop> when you want it	1016	waited. Use an C<ev_async> watcher to wake up C<ev_run> when you want it
922	to take note of any changes you made.	1017	to take note of any changes you made.
923		1018
924	In theory, threads executing C<ev_loop> will be async-cancel safe between	1019	In theory, threads executing C<ev_run> will be async-cancel safe between
925	invocations of C<release> and C<acquire>.	1020	invocations of C<release> and C<acquire>.
926		1021
927	See also the locking example in the C<THREADS> section later in this	1022	See also the locking example in the C<THREADS> section later in this
928	document.	1023	document.
929		1024
930	=item ev_set_userdata (loop, void *data)	1025	=item ev_set_userdata (loop, void *data)
931		1026
932	=item ev_userdata (loop)	1027	=item void *ev_userdata (loop)
933		1028
934	Set and retrieve a single C<void *> associated with a loop. When	1029	Set and retrieve a single C<void *> associated with a loop. When
935	C<ev_set_userdata> has never been called, then C<ev_userdata> returns	1030	C<ev_set_userdata> has never been called, then C<ev_userdata> returns
936	C<0.>	1031	C<0>.
937		1032
938	These two functions can be used to associate arbitrary data with a loop,	1033	These two functions can be used to associate arbitrary data with a loop,
939	and are intended solely for the C<invoke_pending_cb>, C<release> and	1034	and are intended solely for the C<invoke_pending_cb>, C<release> and
940	C<acquire> callbacks described above, but of course can be (ab-)used for	1035	C<acquire> callbacks described above, but of course can be (ab-)used for
941	any other purpose as well.	1036	any other purpose as well.
942		1037
943	=item ev_loop_verify (loop)	1038	=item ev_verify (loop)
944		1039
945	This function only does something when C<EV_VERIFY> support has been	1040	This function only does something when C<EV_VERIFY> support has been
946	compiled in, which is the default for non-minimal builds. It tries to go	1041	compiled in, which is the default for non-minimal builds. It tries to go
947	through all internal structures and checks them for validity. If anything	1042	through all internal structures and checks them for validity. If anything
948	is found to be inconsistent, it will print an error message to standard	1043	is found to be inconsistent, it will print an error message to standard
…		…
959		1054
960	In the following description, uppercase C<TYPE> in names stands for the	1055	In the following description, uppercase C<TYPE> in names stands for the
961	watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer	1056	watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer
962	watchers and C<ev_io_start> for I/O watchers.	1057	watchers and C<ev_io_start> for I/O watchers.
963		1058
964	A watcher is a structure that you create and register to record your	1059	A watcher is an opaque structure that you allocate and register to record
965	interest in some event. For instance, if you want to wait for STDIN to	1060	your interest in some event. To make a concrete example, imagine you want
966	become readable, you would create an C<ev_io> watcher for that:	1061	to wait for STDIN to become readable, you would create an C<ev_io> watcher
		1062	for that:
967		1063
968	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)	1064	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)
969	{	1065	{
970	ev_io_stop (w);	1066	ev_io_stop (w);
971	ev_unloop (loop, EVUNLOOP_ALL);	1067	ev_break (loop, EVBREAK_ALL);
972	}	1068	}
973		1069
974	struct ev_loop *loop = ev_default_loop (0);	1070	struct ev_loop *loop = ev_default_loop (0);
975		1071
976	ev_io stdin_watcher;	1072	ev_io stdin_watcher;
977		1073
978	ev_init (&stdin_watcher, my_cb);	1074	ev_init (&stdin_watcher, my_cb);
979	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	1075	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
980	ev_io_start (loop, &stdin_watcher);	1076	ev_io_start (loop, &stdin_watcher);
981		1077
982	ev_loop (loop, 0);	1078	ev_run (loop, 0);
983		1079
984	As you can see, you are responsible for allocating the memory for your	1080	As you can see, you are responsible for allocating the memory for your
985	watcher structures (and it is I<usually> a bad idea to do this on the	1081	watcher structures (and it is I<usually> a bad idea to do this on the
986	stack).	1082	stack).
987		1083
988	Each watcher has an associated watcher structure (called C<struct ev_TYPE>	1084	Each watcher has an associated watcher structure (called C<struct ev_TYPE>
989	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).	1085	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).
990		1086
991	Each watcher structure must be initialised by a call to C<ev_init	1087	Each watcher structure must be initialised by a call to C<ev_init (watcher
992	(watcher *, callback)>, which expects a callback to be provided. This	1088	*, callback)>, which expects a callback to be provided. This callback is
993	callback gets invoked each time the event occurs (or, in the case of I/O	1089	invoked each time the event occurs (or, in the case of I/O watchers, each
994	watchers, each time the event loop detects that the file descriptor given	1090	time the event loop detects that the file descriptor given is readable
995	is readable and/or writable).	1091	and/or writable).
996		1092
997	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>	1093	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>
998	macro to configure it, with arguments specific to the watcher type. There	1094	macro to configure it, with arguments specific to the watcher type. There
999	is also a macro to combine initialisation and setting in one call: C<<	1095	is also a macro to combine initialisation and setting in one call: C<<
1000	ev_TYPE_init (watcher *, callback, ...) >>.	1096	ev_TYPE_init (watcher *, callback, ...) >>.
…		…
1023	=item C<EV_WRITE>	1119	=item C<EV_WRITE>
1024		1120
1025	The file descriptor in the C<ev_io> watcher has become readable and/or	1121	The file descriptor in the C<ev_io> watcher has become readable and/or
1026	writable.	1122	writable.
1027		1123
1028	=item C<EV_TIMEOUT>	1124	=item C<EV_TIMER>
1029		1125
1030	The C<ev_timer> watcher has timed out.	1126	The C<ev_timer> watcher has timed out.
1031		1127
1032	=item C<EV_PERIODIC>	1128	=item C<EV_PERIODIC>
1033		1129
…		…
1051		1147
1052	=item C<EV_PREPARE>	1148	=item C<EV_PREPARE>
1053		1149
1054	=item C<EV_CHECK>	1150	=item C<EV_CHECK>
1055		1151
1056	All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts	1152	All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts
1057	to gather new events, and all C<ev_check> watchers are invoked just after	1153	to gather new events, and all C<ev_check> watchers are invoked just after
1058	C<ev_loop> has gathered them, but before it invokes any callbacks for any	1154	C<ev_run> has gathered them, but before it invokes any callbacks for any
1059	received events. Callbacks of both watcher types can start and stop as	1155	received events. Callbacks of both watcher types can start and stop as
1060	many watchers as they want, and all of them will be taken into account	1156	many watchers as they want, and all of them will be taken into account
1061	(for example, a C<ev_prepare> watcher might start an idle watcher to keep	1157	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
1062	C<ev_loop> from blocking).	1158	C<ev_run> from blocking).
1063		1159
1064	=item C<EV_EMBED>	1160	=item C<EV_EMBED>
1065		1161
1066	The embedded event loop specified in the C<ev_embed> watcher needs attention.	1162	The embedded event loop specified in the C<ev_embed> watcher needs attention.
1067		1163
1068	=item C<EV_FORK>	1164	=item C<EV_FORK>
1069		1165
1070	The event loop has been resumed in the child process after fork (see	1166	The event loop has been resumed in the child process after fork (see
1071	C<ev_fork>).	1167	C<ev_fork>).
		1168
		1169	=item C<EV_CLEANUP>
		1170
		1171	The event loop is about to be destroyed (see C<ev_cleanup>).
1072		1172
1073	=item C<EV_ASYNC>	1173	=item C<EV_ASYNC>
1074		1174
1075	The given async watcher has been asynchronously notified (see C<ev_async>).	1175	The given async watcher has been asynchronously notified (see C<ev_async>).
1076		1176
…		…
1123		1223
1124	ev_io w;	1224	ev_io w;
1125	ev_init (&w, my_cb);	1225	ev_init (&w, my_cb);
1126	ev_io_set (&w, STDIN_FILENO, EV_READ);	1226	ev_io_set (&w, STDIN_FILENO, EV_READ);
1127		1227
1128	=item C<ev_TYPE_set> (ev_TYPE *, [args])	1228	=item C<ev_TYPE_set> (ev_TYPE *watcher, [args])
1129		1229
1130	This macro initialises the type-specific parts of a watcher. You need to	1230	This macro initialises the type-specific parts of a watcher. You need to
1131	call C<ev_init> at least once before you call this macro, but you can	1231	call C<ev_init> at least once before you call this macro, but you can
1132	call C<ev_TYPE_set> any number of times. You must not, however, call this	1232	call C<ev_TYPE_set> any number of times. You must not, however, call this
1133	macro on a watcher that is active (it can be pending, however, which is a	1233	macro on a watcher that is active (it can be pending, however, which is a
…		…
1146		1246
1147	Example: Initialise and set an C<ev_io> watcher in one step.	1247	Example: Initialise and set an C<ev_io> watcher in one step.
1148		1248
1149	ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ);	1249	ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ);
1150		1250
1151	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)	1251	=item C<ev_TYPE_start> (loop, ev_TYPE *watcher)
1152		1252
1153	Starts (activates) the given watcher. Only active watchers will receive	1253	Starts (activates) the given watcher. Only active watchers will receive
1154	events. If the watcher is already active nothing will happen.	1254	events. If the watcher is already active nothing will happen.
1155		1255
1156	Example: Start the C<ev_io> watcher that is being abused as example in this	1256	Example: Start the C<ev_io> watcher that is being abused as example in this
1157	whole section.	1257	whole section.
1158		1258
1159	ev_io_start (EV_DEFAULT_UC, &w);	1259	ev_io_start (EV_DEFAULT_UC, &w);
1160		1260
1161	=item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher)	1261	=item C<ev_TYPE_stop> (loop, ev_TYPE *watcher)
1162		1262
1163	Stops the given watcher if active, and clears the pending status (whether	1263	Stops the given watcher if active, and clears the pending status (whether
1164	the watcher was active or not).	1264	the watcher was active or not).
1165		1265
1166	It is possible that stopped watchers are pending - for example,	1266	It is possible that stopped watchers are pending - for example,
…		…
1191	=item ev_cb_set (ev_TYPE *watcher, callback)	1291	=item ev_cb_set (ev_TYPE *watcher, callback)
1192		1292
1193	Change the callback. You can change the callback at virtually any time	1293	Change the callback. You can change the callback at virtually any time
1194	(modulo threads).	1294	(modulo threads).
1195		1295
1196	=item ev_set_priority (ev_TYPE *watcher, priority)	1296	=item ev_set_priority (ev_TYPE *watcher, int priority)
1197		1297
1198	=item int ev_priority (ev_TYPE *watcher)	1298	=item int ev_priority (ev_TYPE *watcher)
1199		1299
1200	Set and query the priority of the watcher. The priority is a small	1300	Set and query the priority of the watcher. The priority is a small
1201	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>	1301	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>
…		…
1233	watcher isn't pending it does nothing and returns C<0>.	1333	watcher isn't pending it does nothing and returns C<0>.
1234		1334
1235	Sometimes it can be useful to "poll" a watcher instead of waiting for its	1335	Sometimes it can be useful to "poll" a watcher instead of waiting for its
1236	callback to be invoked, which can be accomplished with this function.	1336	callback to be invoked, which can be accomplished with this function.
1237		1337
		1338	=item ev_feed_event (loop, ev_TYPE *watcher, int revents)
		1339
		1340	Feeds the given event set into the event loop, as if the specified event
		1341	had happened for the specified watcher (which must be a pointer to an
		1342	initialised but not necessarily started event watcher). Obviously you must
		1343	not free the watcher as long as it has pending events.
		1344
		1345	Stopping the watcher, letting libev invoke it, or calling
		1346	C<ev_clear_pending> will clear the pending event, even if the watcher was
		1347	not started in the first place.
		1348
		1349	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related
		1350	functions that do not need a watcher.
		1351
1238	=back	1352	=back
1239
1240		1353
1241	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	1354	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
1242		1355
1243	Each watcher has, by default, a member C<void *data> that you can change	1356	Each watcher has, by default, a member C<void *data> that you can change
1244	and read at any time: libev will completely ignore it. This can be used	1357	and read at any time: libev will completely ignore it. This can be used
…		…
1300	t2_cb (EV_P_ ev_timer *w, int revents)	1413	t2_cb (EV_P_ ev_timer *w, int revents)
1301	{	1414	{
1302	struct my_biggy big = (struct my_biggy *)	1415	struct my_biggy big = (struct my_biggy *)
1303	(((char *)w) - offsetof (struct my_biggy, t2));	1416	(((char *)w) - offsetof (struct my_biggy, t2));
1304	}	1417	}
		1418
		1419	=head2 WATCHER STATES
		1420
		1421	There are various watcher states mentioned throughout this manual -
		1422	active, pending and so on. In this section these states and the rules to
		1423	transition between them will be described in more detail - and while these
		1424	rules might look complicated, they usually do "the right thing".
		1425
		1426	=over 4
		1427
		1428	=item initialiased
		1429
		1430	Before a watcher can be registered with the event looop it has to be
		1431	initialised. This can be done with a call to C<ev_TYPE_init>, or calls to
		1432	C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function.
		1433
		1434	In this state it is simply some block of memory that is suitable for use
		1435	in an event loop. It can be moved around, freed, reused etc. at will.
		1436
		1437	=item started/running/active
		1438
		1439	Once a watcher has been started with a call to C<ev_TYPE_start> it becomes
		1440	property of the event loop, and is actively waiting for events. While in
		1441	this state it cannot be accessed (except in a few documented ways), moved,
		1442	freed or anything else - the only legal thing is to keep a pointer to it,
		1443	and call libev functions on it that are documented to work on active watchers.
		1444
		1445	=item pending
		1446
		1447	If a watcher is active and libev determines that an event it is interested
		1448	in has occurred (such as a timer expiring), it will become pending. It will
		1449	stay in this pending state until either it is stopped or its callback is
		1450	about to be invoked, so it is not normally pending inside the watcher
		1451	callback.
		1452
		1453	The watcher might or might not be active while it is pending (for example,
		1454	an expired non-repeating timer can be pending but no longer active). If it
		1455	is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>),
		1456	but it is still property of the event loop at this time, so cannot be
		1457	moved, freed or reused. And if it is active the rules described in the
		1458	previous item still apply.
		1459
		1460	It is also possible to feed an event on a watcher that is not active (e.g.
		1461	via C<ev_feed_event>), in which case it becomes pending without being
		1462	active.
		1463
		1464	=item stopped
		1465
		1466	A watcher can be stopped implicitly by libev (in which case it might still
		1467	be pending), or explicitly by calling its C<ev_TYPE_stop> function. The
		1468	latter will clear any pending state the watcher might be in, regardless
		1469	of whether it was active or not, so stopping a watcher explicitly before
		1470	freeing it is often a good idea.
		1471
		1472	While stopped (and not pending) the watcher is essentially in the
		1473	initialised state, that is it can be reused, moved, modified in any way
		1474	you wish.
		1475
		1476	=back
1305		1477
1306	=head2 WATCHER PRIORITY MODELS	1478	=head2 WATCHER PRIORITY MODELS
1307		1479
1308	Many event loops support I<watcher priorities>, which are usually small	1480	Many event loops support I<watcher priorities>, which are usually small
1309	integers that influence the ordering of event callback invocation	1481	integers that influence the ordering of event callback invocation
…		…
1352		1524
1353	For example, to emulate how many other event libraries handle priorities,	1525	For example, to emulate how many other event libraries handle priorities,
1354	you can associate an C<ev_idle> watcher to each such watcher, and in	1526	you can associate an C<ev_idle> watcher to each such watcher, and in
1355	the normal watcher callback, you just start the idle watcher. The real	1527	the normal watcher callback, you just start the idle watcher. The real
1356	processing is done in the idle watcher callback. This causes libev to	1528	processing is done in the idle watcher callback. This causes libev to
1357	continously poll and process kernel event data for the watcher, but when	1529	continuously poll and process kernel event data for the watcher, but when
1358	the lock-out case is known to be rare (which in turn is rare :), this is	1530	the lock-out case is known to be rare (which in turn is rare :), this is
1359	workable.	1531	workable.
1360		1532
1361	Usually, however, the lock-out model implemented that way will perform	1533	Usually, however, the lock-out model implemented that way will perform
1362	miserably under the type of load it was designed to handle. In that case,	1534	miserably under the type of load it was designed to handle. In that case,
…		…
1376	{	1548	{
1377	// stop the I/O watcher, we received the event, but	1549	// stop the I/O watcher, we received the event, but
1378	// are not yet ready to handle it.	1550	// are not yet ready to handle it.
1379	ev_io_stop (EV_A_ w);	1551	ev_io_stop (EV_A_ w);
1380		1552
1381	// start the idle watcher to ahndle the actual event.	1553	// start the idle watcher to handle the actual event.
1382	// it will not be executed as long as other watchers	1554	// it will not be executed as long as other watchers
1383	// with the default priority are receiving events.	1555	// with the default priority are receiving events.
1384	ev_idle_start (EV_A_ &idle);	1556	ev_idle_start (EV_A_ &idle);
1385	}	1557	}
1386		1558
…		…
1440		1612
1441	If you cannot use non-blocking mode, then force the use of a	1613	If you cannot use non-blocking mode, then force the use of a
1442	known-to-be-good backend (at the time of this writing, this includes only	1614	known-to-be-good backend (at the time of this writing, this includes only
1443	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file	1615	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file
1444	descriptors for which non-blocking operation makes no sense (such as	1616	descriptors for which non-blocking operation makes no sense (such as
1445	files) - libev doesn't guarentee any specific behaviour in that case.	1617	files) - libev doesn't guarantee any specific behaviour in that case.
1446		1618
1447	Another thing you have to watch out for is that it is quite easy to	1619	Another thing you have to watch out for is that it is quite easy to
1448	receive "spurious" readiness notifications, that is your callback might	1620	receive "spurious" readiness notifications, that is your callback might
1449	be called with C<EV_READ> but a subsequent C<read>(2) will actually block	1621	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
1450	because there is no data. Not only are some backends known to create a	1622	because there is no data. Not only are some backends known to create a
…		…
1515		1687
1516	So when you encounter spurious, unexplained daemon exits, make sure you	1688	So when you encounter spurious, unexplained daemon exits, make sure you
1517	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon	1689	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon
1518	somewhere, as that would have given you a big clue).	1690	somewhere, as that would have given you a big clue).
1519		1691
		1692	=head3 The special problem of accept()ing when you can't
		1693
		1694	Many implementations of the POSIX C<accept> function (for example,
		1695	found in post-2004 Linux) have the peculiar behaviour of not removing a
		1696	connection from the pending queue in all error cases.
		1697
		1698	For example, larger servers often run out of file descriptors (because
		1699	of resource limits), causing C<accept> to fail with C<ENFILE> but not
		1700	rejecting the connection, leading to libev signalling readiness on
		1701	the next iteration again (the connection still exists after all), and
		1702	typically causing the program to loop at 100% CPU usage.
		1703
		1704	Unfortunately, the set of errors that cause this issue differs between
		1705	operating systems, there is usually little the app can do to remedy the
		1706	situation, and no known thread-safe method of removing the connection to
		1707	cope with overload is known (to me).
		1708
		1709	One of the easiest ways to handle this situation is to just ignore it
		1710	- when the program encounters an overload, it will just loop until the
		1711	situation is over. While this is a form of busy waiting, no OS offers an
		1712	event-based way to handle this situation, so it's the best one can do.
		1713
		1714	A better way to handle the situation is to log any errors other than
		1715	C<EAGAIN> and C<EWOULDBLOCK>, making sure not to flood the log with such
		1716	messages, and continue as usual, which at least gives the user an idea of
		1717	what could be wrong ("raise the ulimit!"). For extra points one could stop
		1718	the C<ev_io> watcher on the listening fd "for a while", which reduces CPU
		1719	usage.
		1720
		1721	If your program is single-threaded, then you could also keep a dummy file
		1722	descriptor for overload situations (e.g. by opening F</dev/null>), and
		1723	when you run into C<ENFILE> or C<EMFILE>, close it, run C<accept>,
		1724	close that fd, and create a new dummy fd. This will gracefully refuse
		1725	clients under typical overload conditions.
		1726
		1727	The last way to handle it is to simply log the error and C<exit>, as
		1728	is often done with C<malloc> failures, but this results in an easy
		1729	opportunity for a DoS attack.
1520		1730
1521	=head3 Watcher-Specific Functions	1731	=head3 Watcher-Specific Functions
1522		1732
1523	=over 4	1733	=over 4
1524		1734
…		…
1556	...	1766	...
1557	struct ev_loop *loop = ev_default_init (0);	1767	struct ev_loop *loop = ev_default_init (0);
1558	ev_io stdin_readable;	1768	ev_io stdin_readable;
1559	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1769	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1560	ev_io_start (loop, &stdin_readable);	1770	ev_io_start (loop, &stdin_readable);
1561	ev_loop (loop, 0);	1771	ev_run (loop, 0);
1562		1772
1563		1773
1564	=head2 C<ev_timer> - relative and optionally repeating timeouts	1774	=head2 C<ev_timer> - relative and optionally repeating timeouts
1565		1775
1566	Timer watchers are simple relative timers that generate an event after a	1776	Timer watchers are simple relative timers that generate an event after a
…		…
1575	The callback is guaranteed to be invoked only I<after> its timeout has	1785	The callback is guaranteed to be invoked only I<after> its timeout has
1576	passed (not I<at>, so on systems with very low-resolution clocks this	1786	passed (not I<at>, so on systems with very low-resolution clocks this
1577	might introduce a small delay). If multiple timers become ready during the	1787	might introduce a small delay). If multiple timers become ready during the
1578	same loop iteration then the ones with earlier time-out values are invoked	1788	same loop iteration then the ones with earlier time-out values are invoked
1579	before ones of the same priority with later time-out values (but this is	1789	before ones of the same priority with later time-out values (but this is
1580	no longer true when a callback calls C<ev_loop> recursively).	1790	no longer true when a callback calls C<ev_run> recursively).
1581		1791
1582	=head3 Be smart about timeouts	1792	=head3 Be smart about timeouts
1583		1793
1584	Many real-world problems involve some kind of timeout, usually for error	1794	Many real-world problems involve some kind of timeout, usually for error
1585	recovery. A typical example is an HTTP request - if the other side hangs,	1795	recovery. A typical example is an HTTP request - if the other side hangs,
…		…
1671	ev_tstamp timeout = last_activity + 60.;	1881	ev_tstamp timeout = last_activity + 60.;
1672		1882
1673	// if last_activity + 60. is older than now, we did time out	1883	// if last_activity + 60. is older than now, we did time out
1674	if (timeout < now)	1884	if (timeout < now)
1675	{	1885	{
1676	// timeout occured, take action	1886	// timeout occurred, take action
1677	}	1887	}
1678	else	1888	else
1679	{	1889	{
1680	// callback was invoked, but there was some activity, re-arm	1890	// callback was invoked, but there was some activity, re-arm
1681	// the watcher to fire in last_activity + 60, which is	1891	// the watcher to fire in last_activity + 60, which is
…		…
1703	to the current time (meaning we just have some activity :), then call the	1913	to the current time (meaning we just have some activity :), then call the
1704	callback, which will "do the right thing" and start the timer:	1914	callback, which will "do the right thing" and start the timer:
1705		1915
1706	ev_init (timer, callback);	1916	ev_init (timer, callback);
1707	last_activity = ev_now (loop);	1917	last_activity = ev_now (loop);
1708	callback (loop, timer, EV_TIMEOUT);	1918	callback (loop, timer, EV_TIMER);
1709		1919
1710	And when there is some activity, simply store the current time in	1920	And when there is some activity, simply store the current time in
1711	C<last_activity>, no libev calls at all:	1921	C<last_activity>, no libev calls at all:
1712		1922
1713	last_actiivty = ev_now (loop);	1923	last_activity = ev_now (loop);
1714		1924
1715	This technique is slightly more complex, but in most cases where the	1925	This technique is slightly more complex, but in most cases where the
1716	time-out is unlikely to be triggered, much more efficient.	1926	time-out is unlikely to be triggered, much more efficient.
1717		1927
1718	Changing the timeout is trivial as well (if it isn't hard-coded in the	1928	Changing the timeout is trivial as well (if it isn't hard-coded in the
…		…
1756		1966
1757	=head3 The special problem of time updates	1967	=head3 The special problem of time updates
1758		1968
1759	Establishing the current time is a costly operation (it usually takes at	1969	Establishing the current time is a costly operation (it usually takes at
1760	least two system calls): EV therefore updates its idea of the current	1970	least two system calls): EV therefore updates its idea of the current
1761	time only before and after C<ev_loop> collects new events, which causes a	1971	time only before and after C<ev_run> collects new events, which causes a
1762	growing difference between C<ev_now ()> and C<ev_time ()> when handling	1972	growing difference between C<ev_now ()> and C<ev_time ()> when handling
1763	lots of events in one iteration.	1973	lots of events in one iteration.
1764		1974
1765	The relative timeouts are calculated relative to the C<ev_now ()>	1975	The relative timeouts are calculated relative to the C<ev_now ()>
1766	time. This is usually the right thing as this timestamp refers to the time	1976	time. This is usually the right thing as this timestamp refers to the time
…		…
1837	C<repeat> value), or reset the running timer to the C<repeat> value.	2047	C<repeat> value), or reset the running timer to the C<repeat> value.
1838		2048
1839	This sounds a bit complicated, see L<Be smart about timeouts>, above, for a	2049	This sounds a bit complicated, see L<Be smart about timeouts>, above, for a
1840	usage example.	2050	usage example.
1841		2051
1842	=item ev_timer_remaining (loop, ev_timer *)	2052	=item ev_tstamp ev_timer_remaining (loop, ev_timer *)
1843		2053
1844	Returns the remaining time until a timer fires. If the timer is active,	2054	Returns the remaining time until a timer fires. If the timer is active,
1845	then this time is relative to the current event loop time, otherwise it's	2055	then this time is relative to the current event loop time, otherwise it's
1846	the timeout value currently configured.	2056	the timeout value currently configured.
1847		2057
1848	That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns	2058	That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns
1849	C<5>. When the timer is started and one second passes, C<ev_timer_remain>	2059	C<5>. When the timer is started and one second passes, C<ev_timer_remaining>
1850	will return C<4>. When the timer expires and is restarted, it will return	2060	will return C<4>. When the timer expires and is restarted, it will return
1851	roughly C<7> (likely slightly less as callback invocation takes some time,	2061	roughly C<7> (likely slightly less as callback invocation takes some time,
1852	too), and so on.	2062	too), and so on.
1853		2063
1854	=item ev_tstamp repeat [read-write]	2064	=item ev_tstamp repeat [read-write]
…		…
1883	}	2093	}
1884		2094
1885	ev_timer mytimer;	2095	ev_timer mytimer;
1886	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	2096	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1887	ev_timer_again (&mytimer); /* start timer */	2097	ev_timer_again (&mytimer); /* start timer */
1888	ev_loop (loop, 0);	2098	ev_run (loop, 0);
1889		2099
1890	// and in some piece of code that gets executed on any "activity":	2100	// and in some piece of code that gets executed on any "activity":
1891	// reset the timeout to start ticking again at 10 seconds	2101	// reset the timeout to start ticking again at 10 seconds
1892	ev_timer_again (&mytimer);	2102	ev_timer_again (&mytimer);
1893		2103
…		…
1919		2129
1920	As with timers, the callback is guaranteed to be invoked only when the	2130	As with timers, the callback is guaranteed to be invoked only when the
1921	point in time where it is supposed to trigger has passed. If multiple	2131	point in time where it is supposed to trigger has passed. If multiple
1922	timers become ready during the same loop iteration then the ones with	2132	timers become ready during the same loop iteration then the ones with
1923	earlier time-out values are invoked before ones with later time-out values	2133	earlier time-out values are invoked before ones with later time-out values
1924	(but this is no longer true when a callback calls C<ev_loop> recursively).	2134	(but this is no longer true when a callback calls C<ev_run> recursively).
1925		2135
1926	=head3 Watcher-Specific Functions and Data Members	2136	=head3 Watcher-Specific Functions and Data Members
1927		2137
1928	=over 4	2138	=over 4
1929		2139
…		…
2057	Example: Call a callback every hour, or, more precisely, whenever the	2267	Example: Call a callback every hour, or, more precisely, whenever the
2058	system time is divisible by 3600. The callback invocation times have	2268	system time is divisible by 3600. The callback invocation times have
2059	potentially a lot of jitter, but good long-term stability.	2269	potentially a lot of jitter, but good long-term stability.
2060		2270
2061	static void	2271	static void
2062	clock_cb (struct ev_loop *loop, ev_io *w, int revents)	2272	clock_cb (struct ev_loop *loop, ev_periodic *w, int revents)
2063	{	2273	{
2064	... its now a full hour (UTC, or TAI or whatever your clock follows)	2274	... its now a full hour (UTC, or TAI or whatever your clock follows)
2065	}	2275	}
2066		2276
2067	ev_periodic hourly_tick;	2277	ev_periodic hourly_tick;
…		…
2090		2300
2091	=head2 C<ev_signal> - signal me when a signal gets signalled!	2301	=head2 C<ev_signal> - signal me when a signal gets signalled!
2092		2302
2093	Signal watchers will trigger an event when the process receives a specific	2303	Signal watchers will trigger an event when the process receives a specific
2094	signal one or more times. Even though signals are very asynchronous, libev	2304	signal one or more times. Even though signals are very asynchronous, libev
2095	will try it's best to deliver signals synchronously, i.e. as part of the	2305	will try its best to deliver signals synchronously, i.e. as part of the
2096	normal event processing, like any other event.	2306	normal event processing, like any other event.
2097		2307
2098	If you want signals to be delivered truly asynchronously, just use	2308	If you want signals to be delivered truly asynchronously, just use
2099	C<sigaction> as you would do without libev and forget about sharing	2309	C<sigaction> as you would do without libev and forget about sharing
2100	the signal. You can even use C<ev_async> from a signal handler to	2310	the signal. You can even use C<ev_async> from a signal handler to
…		…
2114	C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should	2324	C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should
2115	not be unduly interrupted. If you have a problem with system calls getting	2325	not be unduly interrupted. If you have a problem with system calls getting
2116	interrupted by signals you can block all signals in an C<ev_check> watcher	2326	interrupted by signals you can block all signals in an C<ev_check> watcher
2117	and unblock them in an C<ev_prepare> watcher.	2327	and unblock them in an C<ev_prepare> watcher.
2118		2328
2119	=head3 The special problem of inheritance over execve	2329	=head3 The special problem of inheritance over fork/execve/pthread_create
2120		2330
2121	Both the signal mask (C<sigprocmask>) and the signal disposition	2331	Both the signal mask (C<sigprocmask>) and the signal disposition
2122	(C<sigaction>) are unspecified after starting a signal watcher (and after	2332	(C<sigaction>) are unspecified after starting a signal watcher (and after
2123	stopping it again), that is, libev might or might not block the signal,	2333	stopping it again), that is, libev might or might not block the signal,
2124	and might or might not set or restore the installed signal handler.	2334	and might or might not set or restore the installed signal handler.
2125		2335
2126	While this does not matter for the signal disposition (libev never	2336	While this does not matter for the signal disposition (libev never
2127	sets signals to C<SIG_IGN>, so handlers will be reset to C<SIG_DFL> on	2337	sets signals to C<SIG_IGN>, so handlers will be reset to C<SIG_DFL> on
2128	C<execve>), this matters for the signal mask: many programs do not expect	2338	C<execve>), this matters for the signal mask: many programs do not expect
2129	many signals to be blocked.	2339	certain signals to be blocked.
2130		2340
2131	This means that before calling C<exec> (from the child) you should reset	2341	This means that before calling C<exec> (from the child) you should reset
2132	the signal mask to whatever "default" you expect (all clear is a good	2342	the signal mask to whatever "default" you expect (all clear is a good
2133	choice usually).	2343	choice usually).
2134		2344
		2345	The simplest way to ensure that the signal mask is reset in the child is
		2346	to install a fork handler with C<pthread_atfork> that resets it. That will
		2347	catch fork calls done by libraries (such as the libc) as well.
		2348
		2349	In current versions of libev, the signal will not be blocked indefinitely
		2350	unless you use the C<signalfd> API (C<EV_SIGNALFD>). While this reduces
		2351	the window of opportunity for problems, it will not go away, as libev
		2352	I<has> to modify the signal mask, at least temporarily.
		2353
		2354	So I can't stress this enough: I<If you do not reset your signal mask when
		2355	you expect it to be empty, you have a race condition in your code>. This
		2356	is not a libev-specific thing, this is true for most event libraries.
		2357
		2358	=head3 The special problem of threads signal handling
		2359
		2360	POSIX threads has problematic signal handling semantics, specifically,
		2361	a lot of functionality (sigfd, sigwait etc.) only really works if all
		2362	threads in a process block signals, which is hard to achieve.
		2363
		2364	When you want to use sigwait (or mix libev signal handling with your own
		2365	for the same signals), you can tackle this problem by globally blocking
		2366	all signals before creating any threads (or creating them with a fully set
		2367	sigprocmask) and also specifying the C<EVFLAG_NOSIGMASK> when creating
		2368	loops. Then designate one thread as "signal receiver thread" which handles
		2369	these signals. You can pass on any signals that libev might be interested
		2370	in by calling C<ev_feed_signal>.
		2371
2135	=head3 Watcher-Specific Functions and Data Members	2372	=head3 Watcher-Specific Functions and Data Members
2136		2373
2137	=over 4	2374	=over 4
2138		2375
2139	=item ev_signal_init (ev_signal *, callback, int signum)	2376	=item ev_signal_init (ev_signal *, callback, int signum)
…		…
2154	Example: Try to exit cleanly on SIGINT.	2391	Example: Try to exit cleanly on SIGINT.
2155		2392
2156	static void	2393	static void
2157	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)	2394	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)
2158	{	2395	{
2159	ev_unloop (loop, EVUNLOOP_ALL);	2396	ev_break (loop, EVBREAK_ALL);
2160	}	2397	}
2161		2398
2162	ev_signal signal_watcher;	2399	ev_signal signal_watcher;
2163	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	2400	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
2164	ev_signal_start (loop, &signal_watcher);	2401	ev_signal_start (loop, &signal_watcher);
…		…
2550		2787
2551	Prepare and check watchers are usually (but not always) used in pairs:	2788	Prepare and check watchers are usually (but not always) used in pairs:
2552	prepare watchers get invoked before the process blocks and check watchers	2789	prepare watchers get invoked before the process blocks and check watchers
2553	afterwards.	2790	afterwards.
2554		2791
2555	You I<must not> call C<ev_loop> or similar functions that enter	2792	You I<must not> call C<ev_run> or similar functions that enter
2556	the current event loop from either C<ev_prepare> or C<ev_check>	2793	the current event loop from either C<ev_prepare> or C<ev_check>
2557	watchers. Other loops than the current one are fine, however. The	2794	watchers. Other loops than the current one are fine, however. The
2558	rationale behind this is that you do not need to check for recursion in	2795	rationale behind this is that you do not need to check for recursion in
2559	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,	2796	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,
2560	C<ev_check> so if you have one watcher of each kind they will always be	2797	C<ev_check> so if you have one watcher of each kind they will always be
…		…
2728		2965
2729	if (timeout >= 0)	2966	if (timeout >= 0)
2730	// create/start timer	2967	// create/start timer
2731		2968
2732	// poll	2969	// poll
2733	ev_loop (EV_A_ 0);	2970	ev_run (EV_A_ 0);
2734		2971
2735	// stop timer again	2972	// stop timer again
2736	if (timeout >= 0)	2973	if (timeout >= 0)
2737	ev_timer_stop (EV_A_ &to);	2974	ev_timer_stop (EV_A_ &to);
2738		2975
…		…
2816	if you do not want that, you need to temporarily stop the embed watcher).	3053	if you do not want that, you need to temporarily stop the embed watcher).
2817		3054
2818	=item ev_embed_sweep (loop, ev_embed *)	3055	=item ev_embed_sweep (loop, ev_embed *)
2819		3056
2820	Make a single, non-blocking sweep over the embedded loop. This works	3057	Make a single, non-blocking sweep over the embedded loop. This works
2821	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	3058	similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most
2822	appropriate way for embedded loops.	3059	appropriate way for embedded loops.
2823		3060
2824	=item struct ev_loop *other [read-only]	3061	=item struct ev_loop *other [read-only]
2825		3062
2826	The embedded event loop.	3063	The embedded event loop.
…		…
2886	C<ev_default_fork> cheats and calls it in the wrong process, the fork	3123	C<ev_default_fork> cheats and calls it in the wrong process, the fork
2887	handlers will be invoked, too, of course.	3124	handlers will be invoked, too, of course.
2888		3125
2889	=head3 The special problem of life after fork - how is it possible?	3126	=head3 The special problem of life after fork - how is it possible?
2890		3127
2891	Most uses of C<fork()> consist of forking, then some simple calls to ste	3128	Most uses of C<fork()> consist of forking, then some simple calls to set
2892	up/change the process environment, followed by a call to C<exec()>. This	3129	up/change the process environment, followed by a call to C<exec()>. This
2893	sequence should be handled by libev without any problems.	3130	sequence should be handled by libev without any problems.
2894		3131
2895	This changes when the application actually wants to do event handling	3132	This changes when the application actually wants to do event handling
2896	in the child, or both parent in child, in effect "continuing" after the	3133	in the child, or both parent in child, in effect "continuing" after the
…		…
2912	disadvantage of having to use multiple event loops (which do not support	3149	disadvantage of having to use multiple event loops (which do not support
2913	signal watchers).	3150	signal watchers).
2914		3151
2915	When this is not possible, or you want to use the default loop for	3152	When this is not possible, or you want to use the default loop for
2916	other reasons, then in the process that wants to start "fresh", call	3153	other reasons, then in the process that wants to start "fresh", call
2917	C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying	3154	C<ev_loop_destroy (EV_DEFAULT)> followed by C<ev_default_loop (...)>.
2918	the default loop will "orphan" (not stop) all registered watchers, so you	3155	Destroying the default loop will "orphan" (not stop) all registered
2919	have to be careful not to execute code that modifies those watchers. Note	3156	watchers, so you have to be careful not to execute code that modifies
2920	also that in that case, you have to re-register any signal watchers.	3157	those watchers. Note also that in that case, you have to re-register any
		3158	signal watchers.
2921		3159
2922	=head3 Watcher-Specific Functions and Data Members	3160	=head3 Watcher-Specific Functions and Data Members
2923		3161
2924	=over 4	3162	=over 4
2925		3163
2926	=item ev_fork_init (ev_signal *, callback)	3164	=item ev_fork_init (ev_fork *, callback)
2927		3165
2928	Initialises and configures the fork watcher - it has no parameters of any	3166	Initialises and configures the fork watcher - it has no parameters of any
2929	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,	3167	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
2930	believe me.	3168	really.
2931		3169
2932	=back	3170	=back
2933		3171
2934		3172
		3173	=head2 C<ev_cleanup> - even the best things end
		3174
		3175	Cleanup watchers are called just before the event loop is being destroyed
		3176	by a call to C<ev_loop_destroy>.
		3177
		3178	While there is no guarantee that the event loop gets destroyed, cleanup
		3179	watchers provide a convenient method to install cleanup hooks for your
		3180	program, worker threads and so on - you just to make sure to destroy the
		3181	loop when you want them to be invoked.
		3182
		3183	Cleanup watchers are invoked in the same way as any other watcher. Unlike
		3184	all other watchers, they do not keep a reference to the event loop (which
		3185	makes a lot of sense if you think about it). Like all other watchers, you
		3186	can call libev functions in the callback, except C<ev_cleanup_start>.
		3187
		3188	=head3 Watcher-Specific Functions and Data Members
		3189
		3190	=over 4
		3191
		3192	=item ev_cleanup_init (ev_cleanup *, callback)
		3193
		3194	Initialises and configures the cleanup watcher - it has no parameters of
		3195	any kind. There is a C<ev_cleanup_set> macro, but using it is utterly
		3196	pointless, I assure you.
		3197
		3198	=back
		3199
		3200	Example: Register an atexit handler to destroy the default loop, so any
		3201	cleanup functions are called.
		3202
		3203	static void
		3204	program_exits (void)
		3205	{
		3206	ev_loop_destroy (EV_DEFAULT_UC);
		3207	}
		3208
		3209	...
		3210	atexit (program_exits);
		3211
		3212
2935	=head2 C<ev_async> - how to wake up another event loop	3213	=head2 C<ev_async> - how to wake up an event loop
2936		3214
2937	In general, you cannot use an C<ev_loop> from multiple threads or other	3215	In general, you cannot use an C<ev_run> from multiple threads or other
2938	asynchronous sources such as signal handlers (as opposed to multiple event	3216	asynchronous sources such as signal handlers (as opposed to multiple event
2939	loops - those are of course safe to use in different threads).	3217	loops - those are of course safe to use in different threads).
2940		3218
2941	Sometimes, however, you need to wake up another event loop you do not	3219	Sometimes, however, you need to wake up an event loop you do not control,
2942	control, for example because it belongs to another thread. This is what	3220	for example because it belongs to another thread. This is what C<ev_async>
2943	C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you	3221	watchers do: as long as the C<ev_async> watcher is active, you can signal
2944	can signal it by calling C<ev_async_send>, which is thread- and signal	3222	it by calling C<ev_async_send>, which is thread- and signal safe.
2945	safe.
2946		3223
2947	This functionality is very similar to C<ev_signal> watchers, as signals,	3224	This functionality is very similar to C<ev_signal> watchers, as signals,
2948	too, are asynchronous in nature, and signals, too, will be compressed	3225	too, are asynchronous in nature, and signals, too, will be compressed
2949	(i.e. the number of callback invocations may be less than the number of	3226	(i.e. the number of callback invocations may be less than the number of
2950	C<ev_async_sent> calls).	3227	C<ev_async_sent> calls). In fact, you could use signal watchers as a kind
		3228	of "global async watchers" by using a watcher on an otherwise unused
		3229	signal, and C<ev_feed_signal> to signal this watcher from another thread,
		3230	even without knowing which loop owns the signal.
2951		3231
2952	Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not	3232	Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not
2953	just the default loop.	3233	just the default loop.
2954		3234
2955	=head3 Queueing	3235	=head3 Queueing
2956		3236
2957	C<ev_async> does not support queueing of data in any way. The reason	3237	C<ev_async> does not support queueing of data in any way. The reason
2958	is that the author does not know of a simple (or any) algorithm for a	3238	is that the author does not know of a simple (or any) algorithm for a
2959	multiple-writer-single-reader queue that works in all cases and doesn't	3239	multiple-writer-single-reader queue that works in all cases and doesn't
2960	need elaborate support such as pthreads.	3240	need elaborate support such as pthreads or unportable memory access
		3241	semantics.
2961		3242
2962	That means that if you want to queue data, you have to provide your own	3243	That means that if you want to queue data, you have to provide your own
2963	queue. But at least I can tell you how to implement locking around your	3244	queue. But at least I can tell you how to implement locking around your
2964	queue:	3245	queue:
2965		3246
…		…
3104		3385
3105	If C<timeout> is less than 0, then no timeout watcher will be	3386	If C<timeout> is less than 0, then no timeout watcher will be
3106	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and	3387	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and
3107	repeat = 0) will be started. C<0> is a valid timeout.	3388	repeat = 0) will be started. C<0> is a valid timeout.
3108		3389
3109	The callback has the type C<void (*cb)(int revents, void *arg)> and gets	3390	The callback has the type C<void (*cb)(int revents, void *arg)> and is
3110	passed an C<revents> set like normal event callbacks (a combination of	3391	passed an C<revents> set like normal event callbacks (a combination of
3111	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>	3392	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMER>) and the C<arg>
3112	value passed to C<ev_once>. Note that it is possible to receive I<both>	3393	value passed to C<ev_once>. Note that it is possible to receive I<both>
3113	a timeout and an io event at the same time - you probably should give io	3394	a timeout and an io event at the same time - you probably should give io
3114	events precedence.	3395	events precedence.
3115		3396
3116	Example: wait up to ten seconds for data to appear on STDIN_FILENO.	3397	Example: wait up to ten seconds for data to appear on STDIN_FILENO.
3117		3398
3118	static void stdin_ready (int revents, void *arg)	3399	static void stdin_ready (int revents, void *arg)
3119	{	3400	{
3120	if (revents & EV_READ)	3401	if (revents & EV_READ)
3121	/* stdin might have data for us, joy! */;	3402	/* stdin might have data for us, joy! */;
3122	else if (revents & EV_TIMEOUT)	3403	else if (revents & EV_TIMER)
3123	/* doh, nothing entered */;	3404	/* doh, nothing entered */;
3124	}	3405	}
3125		3406
3126	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	3407	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
3127		3408
3128	=item ev_feed_event (struct ev_loop *, watcher *, int revents)
3129
3130	Feeds the given event set into the event loop, as if the specified event
3131	had happened for the specified watcher (which must be a pointer to an
3132	initialised but not necessarily started event watcher).
3133
3134	=item ev_feed_fd_event (struct ev_loop *, int fd, int revents)	3409	=item ev_feed_fd_event (loop, int fd, int revents)
3135		3410
3136	Feed an event on the given fd, as if a file descriptor backend detected	3411	Feed an event on the given fd, as if a file descriptor backend detected
3137	the given events it.	3412	the given events it.
3138		3413
3139	=item ev_feed_signal_event (struct ev_loop *loop, int signum)	3414	=item ev_feed_signal_event (loop, int signum)
3140		3415
3141	Feed an event as if the given signal occurred (C<loop> must be the default	3416	Feed an event as if the given signal occurred. See also C<ev_feed_signal>,
3142	loop!).	3417	which is async-safe.
		3418
		3419	=back
		3420
		3421
		3422	=head1 COMMON OR USEFUL IDIOMS (OR BOTH)
		3423
		3424	This section explains some common idioms that are not immediately
		3425	obvious. Note that examples are sprinkled over the whole manual, and this
		3426	section only contains stuff that wouldn't fit anywhere else.
		3427
		3428	=over 4
		3429
		3430	=item Model/nested event loop invocations and exit conditions.
		3431
		3432	Often (especially in GUI toolkits) there are places where you have
		3433	I<modal> interaction, which is most easily implemented by recursively
		3434	invoking C<ev_run>.
		3435
		3436	This brings the problem of exiting - a callback might want to finish the
		3437	main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but
		3438	a modal "Are you sure?" dialog is still waiting), or just the nested one
		3439	and not the main one (e.g. user clocked "Ok" in a modal dialog), or some
		3440	other combination: In these cases, C<ev_break> will not work alone.
		3441
		3442	The solution is to maintain "break this loop" variable for each C<ev_run>
		3443	invocation, and use a loop around C<ev_run> until the condition is
		3444	triggered, using C<EVRUN_ONCE>:
		3445
		3446	// main loop
		3447	int exit_main_loop = 0;
		3448
		3449	while (!exit_main_loop)
		3450	ev_run (EV_DEFAULT_ EVRUN_ONCE);
		3451
		3452	// in a model watcher
		3453	int exit_nested_loop = 0;
		3454
		3455	while (!exit_nested_loop)
		3456	ev_run (EV_A_ EVRUN_ONCE);
		3457
		3458	To exit from any of these loops, just set the corresponding exit variable:
		3459
		3460	// exit modal loop
		3461	exit_nested_loop = 1;
		3462
		3463	// exit main program, after modal loop is finished
		3464	exit_main_loop = 1;
		3465
		3466	// exit both
		3467	exit_main_loop = exit_nested_loop = 1;
3143		3468
3144	=back	3469	=back
3145		3470
3146		3471
3147	=head1 LIBEVENT EMULATION	3472	=head1 LIBEVENT EMULATION
3148		3473
3149	Libev offers a compatibility emulation layer for libevent. It cannot	3474	Libev offers a compatibility emulation layer for libevent. It cannot
3150	emulate the internals of libevent, so here are some usage hints:	3475	emulate the internals of libevent, so here are some usage hints:
3151		3476
3152	=over 4	3477	=over 4
		3478
		3479	=item * Only the libevent-1.4.1-beta API is being emulated.
		3480
		3481	This was the newest libevent version available when libev was implemented,
		3482	and is still mostly unchanged in 2010.
3153		3483
3154	=item * Use it by including <event.h>, as usual.	3484	=item * Use it by including <event.h>, as usual.
3155		3485
3156	=item * The following members are fully supported: ev_base, ev_callback,	3486	=item * The following members are fully supported: ev_base, ev_callback,
3157	ev_arg, ev_fd, ev_res, ev_events.	3487	ev_arg, ev_fd, ev_res, ev_events.
…		…
3163	=item * Priorities are not currently supported. Initialising priorities	3493	=item * Priorities are not currently supported. Initialising priorities
3164	will fail and all watchers will have the same priority, even though there	3494	will fail and all watchers will have the same priority, even though there
3165	is an ev_pri field.	3495	is an ev_pri field.
3166		3496
3167	=item * In libevent, the last base created gets the signals, in libev, the	3497	=item * In libevent, the last base created gets the signals, in libev, the
3168	first base created (== the default loop) gets the signals.	3498	base that registered the signal gets the signals.
3169		3499
3170	=item * Other members are not supported.	3500	=item * Other members are not supported.
3171		3501
3172	=item * The libev emulation is I<not> ABI compatible to libevent, you need	3502	=item * The libev emulation is I<not> ABI compatible to libevent, you need
3173	to use the libev header file and library.	3503	to use the libev header file and library.
…		…
3192	Care has been taken to keep the overhead low. The only data member the C++	3522	Care has been taken to keep the overhead low. The only data member the C++
3193	classes add (compared to plain C-style watchers) is the event loop pointer	3523	classes add (compared to plain C-style watchers) is the event loop pointer
3194	that the watcher is associated with (or no additional members at all if	3524	that the watcher is associated with (or no additional members at all if
3195	you disable C<EV_MULTIPLICITY> when embedding libev).	3525	you disable C<EV_MULTIPLICITY> when embedding libev).
3196		3526
3197	Currently, functions, and static and non-static member functions can be	3527	Currently, functions, static and non-static member functions and classes
3198	used as callbacks. Other types should be easy to add as long as they only	3528	with C<operator ()> can be used as callbacks. Other types should be easy
3199	need one additional pointer for context. If you need support for other	3529	to add as long as they only need one additional pointer for context. If
3200	types of functors please contact the author (preferably after implementing	3530	you need support for other types of functors please contact the author
3201	it).	3531	(preferably after implementing it).
3202		3532
3203	Here is a list of things available in the C<ev> namespace:	3533	Here is a list of things available in the C<ev> namespace:
3204		3534
3205	=over 4	3535	=over 4
3206		3536
…		…
3224		3554
3225	=over 4	3555	=over 4
3226		3556
3227	=item ev::TYPE::TYPE ()	3557	=item ev::TYPE::TYPE ()
3228		3558
3229	=item ev::TYPE::TYPE (struct ev_loop *)	3559	=item ev::TYPE::TYPE (loop)
3230		3560
3231	=item ev::TYPE::~TYPE	3561	=item ev::TYPE::~TYPE
3232		3562
3233	The constructor (optionally) takes an event loop to associate the watcher	3563	The constructor (optionally) takes an event loop to associate the watcher
3234	with. If it is omitted, it will use C<EV_DEFAULT>.	3564	with. If it is omitted, it will use C<EV_DEFAULT>.
…		…
3267	myclass obj;	3597	myclass obj;
3268	ev::io iow;	3598	ev::io iow;
3269	iow.set <myclass, &myclass::io_cb> (&obj);	3599	iow.set <myclass, &myclass::io_cb> (&obj);
3270		3600
3271	=item w->set (object *)	3601	=item w->set (object *)
3272
3273	This is an B<experimental> feature that might go away in a future version.
3274		3602
3275	This is a variation of a method callback - leaving out the method to call	3603	This is a variation of a method callback - leaving out the method to call
3276	will default the method to C<operator ()>, which makes it possible to use	3604	will default the method to C<operator ()>, which makes it possible to use
3277	functor objects without having to manually specify the C<operator ()> all	3605	functor objects without having to manually specify the C<operator ()> all
3278	the time. Incidentally, you can then also leave out the template argument	3606	the time. Incidentally, you can then also leave out the template argument
…		…
3311	Example: Use a plain function as callback.	3639	Example: Use a plain function as callback.
3312		3640
3313	static void io_cb (ev::io &w, int revents) { }	3641	static void io_cb (ev::io &w, int revents) { }
3314	iow.set <io_cb> ();	3642	iow.set <io_cb> ();
3315		3643
3316	=item w->set (struct ev_loop *)	3644	=item w->set (loop)
3317		3645
3318	Associates a different C<struct ev_loop> with this watcher. You can only	3646	Associates a different C<struct ev_loop> with this watcher. You can only
3319	do this when the watcher is inactive (and not pending either).	3647	do this when the watcher is inactive (and not pending either).
3320		3648
3321	=item w->set ([arguments])	3649	=item w->set ([arguments])
3322		3650
3323	Basically the same as C<ev_TYPE_set>, with the same arguments. Must be	3651	Basically the same as C<ev_TYPE_set>, with the same arguments. Either this
3324	called at least once. Unlike the C counterpart, an active watcher gets	3652	method or a suitable start method must be called at least once. Unlike the
3325	automatically stopped and restarted when reconfiguring it with this	3653	C counterpart, an active watcher gets automatically stopped and restarted
3326	method.	3654	when reconfiguring it with this method.
3327		3655
3328	=item w->start ()	3656	=item w->start ()
3329		3657
3330	Starts the watcher. Note that there is no C<loop> argument, as the	3658	Starts the watcher. Note that there is no C<loop> argument, as the
3331	constructor already stores the event loop.	3659	constructor already stores the event loop.
3332		3660
		3661	=item w->start ([arguments])
		3662
		3663	Instead of calling C<set> and C<start> methods separately, it is often
		3664	convenient to wrap them in one call. Uses the same type of arguments as
		3665	the configure C<set> method of the watcher.
		3666
3333	=item w->stop ()	3667	=item w->stop ()
3334		3668
3335	Stops the watcher if it is active. Again, no C<loop> argument.	3669	Stops the watcher if it is active. Again, no C<loop> argument.
3336		3670
3337	=item w->again () (C<ev::timer>, C<ev::periodic> only)	3671	=item w->again () (C<ev::timer>, C<ev::periodic> only)
…		…
3349		3683
3350	=back	3684	=back
3351		3685
3352	=back	3686	=back
3353		3687
3354	Example: Define a class with an IO and idle watcher, start one of them in	3688	Example: Define a class with two I/O and idle watchers, start the I/O
3355	the constructor.	3689	watchers in the constructor.
3356		3690
3357	class myclass	3691	class myclass
3358	{	3692	{
3359	ev::io io ; void io_cb (ev::io &w, int revents);	3693	ev::io io ; void io_cb (ev::io &w, int revents);
		3694	ev::io2 io2 ; void io2_cb (ev::io &w, int revents);
3360	ev::idle idle; void idle_cb (ev::idle &w, int revents);	3695	ev::idle idle; void idle_cb (ev::idle &w, int revents);
3361		3696
3362	myclass (int fd)	3697	myclass (int fd)
3363	{	3698	{
3364	io .set <myclass, &myclass::io_cb > (this);	3699	io .set <myclass, &myclass::io_cb > (this);
		3700	io2 .set <myclass, &myclass::io2_cb > (this);
3365	idle.set <myclass, &myclass::idle_cb> (this);	3701	idle.set <myclass, &myclass::idle_cb> (this);
3366		3702
3367	io.start (fd, ev::READ);	3703	io.set (fd, ev::WRITE); // configure the watcher
		3704	io.start (); // start it whenever convenient
		3705
		3706	io2.start (fd, ev::READ); // set + start in one call
3368	}	3707	}
3369	};	3708	};
3370		3709
3371		3710
3372	=head1 OTHER LANGUAGE BINDINGS	3711	=head1 OTHER LANGUAGE BINDINGS
…		…
3420	Erkki Seppala has written Ocaml bindings for libev, to be found at	3759	Erkki Seppala has written Ocaml bindings for libev, to be found at
3421	L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>.	3760	L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>.
3422		3761
3423	=item Lua	3762	=item Lua
3424		3763
3425	Brian Maher has written a partial interface to libev	3764	Brian Maher has written a partial interface to libev for lua (at the
3426	for lua (only C<ev_io> and C<ev_timer>), to be found at	3765	time of this writing, only C<ev_io> and C<ev_timer>), to be found at
3427	L<http://github.com/brimworks/lua-ev>.	3766	L<http://github.com/brimworks/lua-ev>.
3428		3767
3429	=back	3768	=back
3430		3769
3431		3770
…		…
3446	loop argument"). The C<EV_A> form is used when this is the sole argument,	3785	loop argument"). The C<EV_A> form is used when this is the sole argument,
3447	C<EV_A_> is used when other arguments are following. Example:	3786	C<EV_A_> is used when other arguments are following. Example:
3448		3787
3449	ev_unref (EV_A);	3788	ev_unref (EV_A);
3450	ev_timer_add (EV_A_ watcher);	3789	ev_timer_add (EV_A_ watcher);
3451	ev_loop (EV_A_ 0);	3790	ev_run (EV_A_ 0);
3452		3791
3453	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	3792	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
3454	which is often provided by the following macro.	3793	which is often provided by the following macro.
3455		3794
3456	=item C<EV_P>, C<EV_P_>	3795	=item C<EV_P>, C<EV_P_>
…		…
3496	}	3835	}
3497		3836
3498	ev_check check;	3837	ev_check check;
3499	ev_check_init (&check, check_cb);	3838	ev_check_init (&check, check_cb);
3500	ev_check_start (EV_DEFAULT_ &check);	3839	ev_check_start (EV_DEFAULT_ &check);
3501	ev_loop (EV_DEFAULT_ 0);	3840	ev_run (EV_DEFAULT_ 0);
3502		3841
3503	=head1 EMBEDDING	3842	=head1 EMBEDDING
3504		3843
3505	Libev can (and often is) directly embedded into host	3844	Libev can (and often is) directly embedded into host
3506	applications. Examples of applications that embed it include the Deliantra	3845	applications. Examples of applications that embed it include the Deliantra
…		…
3586	libev.m4	3925	libev.m4
3587		3926
3588	=head2 PREPROCESSOR SYMBOLS/MACROS	3927	=head2 PREPROCESSOR SYMBOLS/MACROS
3589		3928
3590	Libev can be configured via a variety of preprocessor symbols you have to	3929	Libev can be configured via a variety of preprocessor symbols you have to
3591	define before including any of its files. The default in the absence of	3930	define before including (or compiling) any of its files. The default in
3592	autoconf is documented for every option.	3931	the absence of autoconf is documented for every option.
		3932
		3933	Symbols marked with "(h)" do not change the ABI, and can have different
		3934	values when compiling libev vs. including F<ev.h>, so it is permissible
		3935	to redefine them before including F<ev.h> without breaking compatibility
		3936	to a compiled library. All other symbols change the ABI, which means all
		3937	users of libev and the libev code itself must be compiled with compatible
		3938	settings.
3593		3939
3594	=over 4	3940	=over 4
3595		3941
		3942	=item EV_COMPAT3 (h)
		3943
		3944	Backwards compatibility is a major concern for libev. This is why this
		3945	release of libev comes with wrappers for the functions and symbols that
		3946	have been renamed between libev version 3 and 4.
		3947
		3948	You can disable these wrappers (to test compatibility with future
		3949	versions) by defining C<EV_COMPAT3> to C<0> when compiling your
		3950	sources. This has the additional advantage that you can drop the C<struct>
		3951	from C<struct ev_loop> declarations, as libev will provide an C<ev_loop>
		3952	typedef in that case.
		3953
		3954	In some future version, the default for C<EV_COMPAT3> will become C<0>,
		3955	and in some even more future version the compatibility code will be
		3956	removed completely.
		3957
3596	=item EV_STANDALONE	3958	=item EV_STANDALONE (h)
3597		3959
3598	Must always be C<1> if you do not use autoconf configuration, which	3960	Must always be C<1> if you do not use autoconf configuration, which
3599	keeps libev from including F<config.h>, and it also defines dummy	3961	keeps libev from including F<config.h>, and it also defines dummy
3600	implementations for some libevent functions (such as logging, which is not	3962	implementations for some libevent functions (such as logging, which is not
3601	supported). It will also not define any of the structs usually found in	3963	supported). It will also not define any of the structs usually found in
…		…
3751	as well as for signal and thread safety in C<ev_async> watchers.	4113	as well as for signal and thread safety in C<ev_async> watchers.
3752		4114
3753	In the absence of this define, libev will use C<sig_atomic_t volatile>	4115	In the absence of this define, libev will use C<sig_atomic_t volatile>
3754	(from F<signal.h>), which is usually good enough on most platforms.	4116	(from F<signal.h>), which is usually good enough on most platforms.
3755		4117
3756	=item EV_H	4118	=item EV_H (h)
3757		4119
3758	The name of the F<ev.h> header file used to include it. The default if	4120	The name of the F<ev.h> header file used to include it. The default if
3759	undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be	4121	undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be
3760	used to virtually rename the F<ev.h> header file in case of conflicts.	4122	used to virtually rename the F<ev.h> header file in case of conflicts.
3761		4123
3762	=item EV_CONFIG_H	4124	=item EV_CONFIG_H (h)
3763		4125
3764	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override	4126	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override
3765	F<ev.c>'s idea of where to find the F<config.h> file, similarly to	4127	F<ev.c>'s idea of where to find the F<config.h> file, similarly to
3766	C<EV_H>, above.	4128	C<EV_H>, above.
3767		4129
3768	=item EV_EVENT_H	4130	=item EV_EVENT_H (h)
3769		4131
3770	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea	4132	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea
3771	of how the F<event.h> header can be found, the default is C<"event.h">.	4133	of how the F<event.h> header can be found, the default is C<"event.h">.
3772		4134
3773	=item EV_PROTOTYPES	4135	=item EV_PROTOTYPES (h)
3774		4136
3775	If defined to be C<0>, then F<ev.h> will not define any function	4137	If defined to be C<0>, then F<ev.h> will not define any function
3776	prototypes, but still define all the structs and other symbols. This is	4138	prototypes, but still define all the structs and other symbols. This is
3777	occasionally useful if you want to provide your own wrapper functions	4139	occasionally useful if you want to provide your own wrapper functions
3778	around libev functions.	4140	around libev functions.
…		…
3800	fine.	4162	fine.
3801		4163
3802	If your embedding application does not need any priorities, defining these	4164	If your embedding application does not need any priorities, defining these
3803	both to C<0> will save some memory and CPU.	4165	both to C<0> will save some memory and CPU.
3804		4166
3805	=item EV_PERIODIC_ENABLE	4167	=item EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE,
		4168	EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE,
		4169	EV_ASYNC_ENABLE, EV_CHILD_ENABLE.
3806		4170
3807	If undefined or defined to be C<1>, then periodic timers are supported. If	4171	If undefined or defined to be C<1> (and the platform supports it), then
3808	defined to be C<0>, then they are not. Disabling them saves a few kB of	4172	the respective watcher type is supported. If defined to be C<0>, then it
3809	code.	4173	is not. Disabling watcher types mainly saves code size.
3810		4174
3811	=item EV_IDLE_ENABLE	4175	=item EV_FEATURES
3812
3813	If undefined or defined to be C<1>, then idle watchers are supported. If
3814	defined to be C<0>, then they are not. Disabling them saves a few kB of
3815	code.
3816
3817	=item EV_EMBED_ENABLE
3818
3819	If undefined or defined to be C<1>, then embed watchers are supported. If
3820	defined to be C<0>, then they are not. Embed watchers rely on most other
3821	watcher types, which therefore must not be disabled.
3822
3823	=item EV_STAT_ENABLE
3824
3825	If undefined or defined to be C<1>, then stat watchers are supported. If
3826	defined to be C<0>, then they are not.
3827
3828	=item EV_FORK_ENABLE
3829
3830	If undefined or defined to be C<1>, then fork watchers are supported. If
3831	defined to be C<0>, then they are not.
3832
3833	=item EV_ASYNC_ENABLE
3834
3835	If undefined or defined to be C<1>, then async watchers are supported. If
3836	defined to be C<0>, then they are not.
3837
3838	=item EV_MINIMAL
3839		4176
3840	If you need to shave off some kilobytes of code at the expense of some	4177	If you need to shave off some kilobytes of code at the expense of some
3841	speed (but with the full API), define this symbol to C<1>. Currently this	4178	speed (but with the full API), you can define this symbol to request
3842	is used to override some inlining decisions, saves roughly 30% code size	4179	certain subsets of functionality. The default is to enable all features
3843	on amd64. It also selects a much smaller 2-heap for timer management over	4180	that can be enabled on the platform.
3844	the default 4-heap.
3845		4181
3846	You can save even more by disabling watcher types you do not need	4182	A typical way to use this symbol is to define it to C<0> (or to a bitset
3847	and setting C<EV_MAXPRI> == C<EV_MINPRI>. Also, disabling C<assert>	4183	with some broad features you want) and then selectively re-enable
3848	(C<-DNDEBUG>) will usually reduce code size a lot.	4184	additional parts you want, for example if you want everything minimal,
		4185	but multiple event loop support, async and child watchers and the poll
		4186	backend, use this:
3849		4187
3850	Defining C<EV_MINIMAL> to C<2> will additionally reduce the core API to	4188	#define EV_FEATURES 0
3851	provide a bare-bones event library. See C<ev.h> for details on what parts	4189	#define EV_MULTIPLICITY 1
3852	of the API are still available, and do not complain if this subset changes	4190	#define EV_USE_POLL 1
3853	over time.	4191	#define EV_CHILD_ENABLE 1
		4192	#define EV_ASYNC_ENABLE 1
		4193
		4194	The actual value is a bitset, it can be a combination of the following
		4195	values:
		4196
		4197	=over 4
		4198
		4199	=item C<1> - faster/larger code
		4200
		4201	Use larger code to speed up some operations.
		4202
		4203	Currently this is used to override some inlining decisions (enlarging the
		4204	code size by roughly 30% on amd64).
		4205
		4206	When optimising for size, use of compiler flags such as C<-Os> with
		4207	gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of
		4208	assertions.
		4209
		4210	=item C<2> - faster/larger data structures
		4211
		4212	Replaces the small 2-heap for timer management by a faster 4-heap, larger
		4213	hash table sizes and so on. This will usually further increase code size
		4214	and can additionally have an effect on the size of data structures at
		4215	runtime.
		4216
		4217	=item C<4> - full API configuration
		4218
		4219	This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and
		4220	enables multiplicity (C<EV_MULTIPLICITY>=1).
		4221
		4222	=item C<8> - full API
		4223
		4224	This enables a lot of the "lesser used" API functions. See C<ev.h> for
		4225	details on which parts of the API are still available without this
		4226	feature, and do not complain if this subset changes over time.
		4227
		4228	=item C<16> - enable all optional watcher types
		4229
		4230	Enables all optional watcher types. If you want to selectively enable
		4231	only some watcher types other than I/O and timers (e.g. prepare,
		4232	embed, async, child...) you can enable them manually by defining
		4233	C<EV_watchertype_ENABLE> to C<1> instead.
		4234
		4235	=item C<32> - enable all backends
		4236
		4237	This enables all backends - without this feature, you need to enable at
		4238	least one backend manually (C<EV_USE_SELECT> is a good choice).
		4239
		4240	=item C<64> - enable OS-specific "helper" APIs
		4241
		4242	Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by
		4243	default.
		4244
		4245	=back
		4246
		4247	Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0>
		4248	reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb
		4249	code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O
		4250	watchers, timers and monotonic clock support.
		4251
		4252	With an intelligent-enough linker (gcc+binutils are intelligent enough
		4253	when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by
		4254	your program might be left out as well - a binary starting a timer and an
		4255	I/O watcher then might come out at only 5Kb.
		4256
		4257	=item EV_AVOID_STDIO
		4258
		4259	If this is set to C<1> at compiletime, then libev will avoid using stdio
		4260	functions (printf, scanf, perror etc.). This will increase the code size
		4261	somewhat, but if your program doesn't otherwise depend on stdio and your
		4262	libc allows it, this avoids linking in the stdio library which is quite
		4263	big.
		4264
		4265	Note that error messages might become less precise when this option is
		4266	enabled.
3854		4267
3855	=item EV_NSIG	4268	=item EV_NSIG
3856		4269
3857	The highest supported signal number, +1 (or, the number of	4270	The highest supported signal number, +1 (or, the number of
3858	signals): Normally, libev tries to deduce the maximum number of signals	4271	signals): Normally, libev tries to deduce the maximum number of signals
3859	automatically, but sometimes this fails, in which case it can be	4272	automatically, but sometimes this fails, in which case it can be
3860	specified. Also, using a lower number than detected (C<32> should be	4273	specified. Also, using a lower number than detected (C<32> should be
3861	good for about any system in existance) can save some memory, as libev	4274	good for about any system in existence) can save some memory, as libev
3862	statically allocates some 12-24 bytes per signal number.	4275	statically allocates some 12-24 bytes per signal number.
3863		4276
3864	=item EV_PID_HASHSIZE	4277	=item EV_PID_HASHSIZE
3865		4278
3866	C<ev_child> watchers use a small hash table to distribute workload by	4279	C<ev_child> watchers use a small hash table to distribute workload by
3867	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more	4280	pid. The default size is C<16> (or C<1> with C<EV_FEATURES> disabled),
3868	than enough. If you need to manage thousands of children you might want to	4281	usually more than enough. If you need to manage thousands of children you
3869	increase this value (I<must> be a power of two).	4282	might want to increase this value (I<must> be a power of two).
3870		4283
3871	=item EV_INOTIFY_HASHSIZE	4284	=item EV_INOTIFY_HASHSIZE
3872		4285
3873	C<ev_stat> watchers use a small hash table to distribute workload by	4286	C<ev_stat> watchers use a small hash table to distribute workload by
3874	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),	4287	inotify watch id. The default size is C<16> (or C<1> with C<EV_FEATURES>
3875	usually more than enough. If you need to manage thousands of C<ev_stat>	4288	disabled), usually more than enough. If you need to manage thousands of
3876	watchers you might want to increase this value (I<must> be a power of	4289	C<ev_stat> watchers you might want to increase this value (I<must> be a
3877	two).	4290	power of two).
3878		4291
3879	=item EV_USE_4HEAP	4292	=item EV_USE_4HEAP
3880		4293
3881	Heaps are not very cache-efficient. To improve the cache-efficiency of the	4294	Heaps are not very cache-efficient. To improve the cache-efficiency of the
3882	timer and periodics heaps, libev uses a 4-heap when this symbol is defined	4295	timer and periodics heaps, libev uses a 4-heap when this symbol is defined
3883	to C<1>. The 4-heap uses more complicated (longer) code but has noticeably	4296	to C<1>. The 4-heap uses more complicated (longer) code but has noticeably
3884	faster performance with many (thousands) of watchers.	4297	faster performance with many (thousands) of watchers.
3885		4298
3886	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>	4299	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3887	(disabled).	4300	will be C<0>.
3888		4301
3889	=item EV_HEAP_CACHE_AT	4302	=item EV_HEAP_CACHE_AT
3890		4303
3891	Heaps are not very cache-efficient. To improve the cache-efficiency of the	4304	Heaps are not very cache-efficient. To improve the cache-efficiency of the
3892	timer and periodics heaps, libev can cache the timestamp (I<at>) within	4305	timer and periodics heaps, libev can cache the timestamp (I<at>) within
3893	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),	4306	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),
3894	which uses 8-12 bytes more per watcher and a few hundred bytes more code,	4307	which uses 8-12 bytes more per watcher and a few hundred bytes more code,
3895	but avoids random read accesses on heap changes. This improves performance	4308	but avoids random read accesses on heap changes. This improves performance
3896	noticeably with many (hundreds) of watchers.	4309	noticeably with many (hundreds) of watchers.
3897		4310
3898	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>	4311	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3899	(disabled).	4312	will be C<0>.
3900		4313
3901	=item EV_VERIFY	4314	=item EV_VERIFY
3902		4315
3903	Controls how much internal verification (see C<ev_loop_verify ()>) will	4316	Controls how much internal verification (see C<ev_verify ()>) will
3904	be done: If set to C<0>, no internal verification code will be compiled	4317	be done: If set to C<0>, no internal verification code will be compiled
3905	in. If set to C<1>, then verification code will be compiled in, but not	4318	in. If set to C<1>, then verification code will be compiled in, but not
3906	called. If set to C<2>, then the internal verification code will be	4319	called. If set to C<2>, then the internal verification code will be
3907	called once per loop, which can slow down libev. If set to C<3>, then the	4320	called once per loop, which can slow down libev. If set to C<3>, then the
3908	verification code will be called very frequently, which will slow down	4321	verification code will be called very frequently, which will slow down
3909	libev considerably.	4322	libev considerably.
3910		4323
3911	The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be	4324	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3912	C<0>.	4325	will be C<0>.
3913		4326
3914	=item EV_COMMON	4327	=item EV_COMMON
3915		4328
3916	By default, all watchers have a C<void *data> member. By redefining	4329	By default, all watchers have a C<void *data> member. By redefining
3917	this macro to a something else you can include more and other types of	4330	this macro to something else you can include more and other types of
3918	members. You have to define it each time you include one of the files,	4331	members. You have to define it each time you include one of the files,
3919	though, and it must be identical each time.	4332	though, and it must be identical each time.
3920		4333
3921	For example, the perl EV module uses something like this:	4334	For example, the perl EV module uses something like this:
3922		4335
…		…
3975	file.	4388	file.
3976		4389
3977	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	4390	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
3978	that everybody includes and which overrides some configure choices:	4391	that everybody includes and which overrides some configure choices:
3979		4392
3980	#define EV_MINIMAL 1	4393	#define EV_FEATURES 8
3981	#define EV_USE_POLL 0	4394	#define EV_USE_SELECT 1
3982	#define EV_MULTIPLICITY 0
3983	#define EV_PERIODIC_ENABLE 0	4395	#define EV_PREPARE_ENABLE 1
		4396	#define EV_IDLE_ENABLE 1
3984	#define EV_STAT_ENABLE 0	4397	#define EV_SIGNAL_ENABLE 1
3985	#define EV_FORK_ENABLE 0	4398	#define EV_CHILD_ENABLE 1
		4399	#define EV_USE_STDEXCEPT 0
3986	#define EV_CONFIG_H <config.h>	4400	#define EV_CONFIG_H <config.h>
3987	#define EV_MINPRI 0
3988	#define EV_MAXPRI 0
3989		4401
3990	#include "ev++.h"	4402	#include "ev++.h"
3991		4403
3992	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	4404	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
3993		4405
…		…
4124	userdata *u = ev_userdata (EV_A);	4536	userdata *u = ev_userdata (EV_A);
4125	pthread_mutex_lock (&u->lock);	4537	pthread_mutex_lock (&u->lock);
4126	}	4538	}
4127		4539
4128	The event loop thread first acquires the mutex, and then jumps straight	4540	The event loop thread first acquires the mutex, and then jumps straight
4129	into C<ev_loop>:	4541	into C<ev_run>:
4130		4542
4131	void *	4543	void *
4132	l_run (void *thr_arg)	4544	l_run (void *thr_arg)
4133	{	4545	{
4134	struct ev_loop *loop = (struct ev_loop *)thr_arg;	4546	struct ev_loop *loop = (struct ev_loop *)thr_arg;
4135		4547
4136	l_acquire (EV_A);	4548	l_acquire (EV_A);
4137	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);	4549	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
4138	ev_loop (EV_A_ 0);	4550	ev_run (EV_A_ 0);
4139	l_release (EV_A);	4551	l_release (EV_A);
4140		4552
4141	return 0;	4553	return 0;
4142	}	4554	}
4143		4555
…		…
4195		4607
4196	=head3 COROUTINES	4608	=head3 COROUTINES
4197		4609
4198	Libev is very accommodating to coroutines ("cooperative threads"):	4610	Libev is very accommodating to coroutines ("cooperative threads"):
4199	libev fully supports nesting calls to its functions from different	4611	libev fully supports nesting calls to its functions from different
4200	coroutines (e.g. you can call C<ev_loop> on the same loop from two	4612	coroutines (e.g. you can call C<ev_run> on the same loop from two
4201	different coroutines, and switch freely between both coroutines running	4613	different coroutines, and switch freely between both coroutines running
4202	the loop, as long as you don't confuse yourself). The only exception is	4614	the loop, as long as you don't confuse yourself). The only exception is
4203	that you must not do this from C<ev_periodic> reschedule callbacks.	4615	that you must not do this from C<ev_periodic> reschedule callbacks.
4204		4616
4205	Care has been taken to ensure that libev does not keep local state inside	4617	Care has been taken to ensure that libev does not keep local state inside
4206	C<ev_loop>, and other calls do not usually allow for coroutine switches as	4618	C<ev_run>, and other calls do not usually allow for coroutine switches as
4207	they do not call any callbacks.	4619	they do not call any callbacks.
4208		4620
4209	=head2 COMPILER WARNINGS	4621	=head2 COMPILER WARNINGS
4210		4622
4211	Depending on your compiler and compiler settings, you might get no or a	4623	Depending on your compiler and compiler settings, you might get no or a
…		…
4222	maintainable.	4634	maintainable.
4223		4635
4224	And of course, some compiler warnings are just plain stupid, or simply	4636	And of course, some compiler warnings are just plain stupid, or simply
4225	wrong (because they don't actually warn about the condition their message	4637	wrong (because they don't actually warn about the condition their message
4226	seems to warn about). For example, certain older gcc versions had some	4638	seems to warn about). For example, certain older gcc versions had some
4227	warnings that resulted an extreme number of false positives. These have	4639	warnings that resulted in an extreme number of false positives. These have
4228	been fixed, but some people still insist on making code warn-free with	4640	been fixed, but some people still insist on making code warn-free with
4229	such buggy versions.	4641	such buggy versions.
4230		4642
4231	While libev is written to generate as few warnings as possible,	4643	While libev is written to generate as few warnings as possible,
4232	"warn-free" code is not a goal, and it is recommended not to build libev	4644	"warn-free" code is not a goal, and it is recommended not to build libev
…		…
4268	I suggest using suppression lists.	4680	I suggest using suppression lists.
4269		4681
4270		4682
4271	=head1 PORTABILITY NOTES	4683	=head1 PORTABILITY NOTES
4272		4684
		4685	=head2 GNU/LINUX 32 BIT LIMITATIONS
		4686
		4687	GNU/Linux is the only common platform that supports 64 bit file/large file
		4688	interfaces but I<disables> them by default.
		4689
		4690	That means that libev compiled in the default environment doesn't support
		4691	files larger than 2GiB or so, which mainly affects C<ev_stat> watchers.
		4692
		4693	Unfortunately, many programs try to work around this GNU/Linux issue
		4694	by enabling the large file API, which makes them incompatible with the
		4695	standard libev compiled for their system.
		4696
		4697	Likewise, libev cannot enable the large file API itself as this would
		4698	suddenly make it incompatible to the default compile time environment,
		4699	i.e. all programs not using special compile switches.
		4700
		4701	=head2 OS/X AND DARWIN BUGS
		4702
		4703	The whole thing is a bug if you ask me - basically any system interface
		4704	you touch is broken, whether it is locales, poll, kqueue or even the
		4705	OpenGL drivers.
		4706
		4707	=head3 C<kqueue> is buggy
		4708
		4709	The kqueue syscall is broken in all known versions - most versions support
		4710	only sockets, many support pipes.
		4711
		4712	Libev tries to work around this by not using C<kqueue> by default on this
		4713	rotten platform, but of course you can still ask for it when creating a
		4714	loop - embedding a socket-only kqueue loop into a select-based one is
		4715	probably going to work well.
		4716
		4717	=head3 C<poll> is buggy
		4718
		4719	Instead of fixing C<kqueue>, Apple replaced their (working) C<poll>
		4720	implementation by something calling C<kqueue> internally around the 10.5.6
		4721	release, so now C<kqueue> I<and> C<poll> are broken.
		4722
		4723	Libev tries to work around this by not using C<poll> by default on
		4724	this rotten platform, but of course you can still ask for it when creating
		4725	a loop.
		4726
		4727	=head3 C<select> is buggy
		4728
		4729	All that's left is C<select>, and of course Apple found a way to fuck this
		4730	one up as well: On OS/X, C<select> actively limits the number of file
		4731	descriptors you can pass in to 1024 - your program suddenly crashes when
		4732	you use more.
		4733
		4734	There is an undocumented "workaround" for this - defining
		4735	C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should>
		4736	work on OS/X.
		4737
		4738	=head2 SOLARIS PROBLEMS AND WORKAROUNDS
		4739
		4740	=head3 C<errno> reentrancy
		4741
		4742	The default compile environment on Solaris is unfortunately so
		4743	thread-unsafe that you can't even use components/libraries compiled
		4744	without C<-D_REENTRANT> in a threaded program, which, of course, isn't
		4745	defined by default. A valid, if stupid, implementation choice.
		4746
		4747	If you want to use libev in threaded environments you have to make sure
		4748	it's compiled with C<_REENTRANT> defined.
		4749
		4750	=head3 Event port backend
		4751
		4752	The scalable event interface for Solaris is called "event
		4753	ports". Unfortunately, this mechanism is very buggy in all major
		4754	releases. If you run into high CPU usage, your program freezes or you get
		4755	a large number of spurious wakeups, make sure you have all the relevant
		4756	and latest kernel patches applied. No, I don't know which ones, but there
		4757	are multiple ones to apply, and afterwards, event ports actually work
		4758	great.
		4759
		4760	If you can't get it to work, you can try running the program by setting
		4761	the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and
		4762	C<select> backends.
		4763
		4764	=head2 AIX POLL BUG
		4765
		4766	AIX unfortunately has a broken C<poll.h> header. Libev works around
		4767	this by trying to avoid the poll backend altogether (i.e. it's not even
		4768	compiled in), which normally isn't a big problem as C<select> works fine
		4769	with large bitsets on AIX, and AIX is dead anyway.
		4770
4273	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS	4771	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
		4772
		4773	=head3 General issues
4274		4774
4275	Win32 doesn't support any of the standards (e.g. POSIX) that libev	4775	Win32 doesn't support any of the standards (e.g. POSIX) that libev
4276	requires, and its I/O model is fundamentally incompatible with the POSIX	4776	requires, and its I/O model is fundamentally incompatible with the POSIX
4277	model. Libev still offers limited functionality on this platform in	4777	model. Libev still offers limited functionality on this platform in
4278	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	4778	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
4279	descriptors. This only applies when using Win32 natively, not when using	4779	descriptors. This only applies when using Win32 natively, not when using
4280	e.g. cygwin.	4780	e.g. cygwin. Actually, it only applies to the microsofts own compilers,
		4781	as every compielr comes with a slightly differently broken/incompatible
		4782	environment.
4281		4783
4282	Lifting these limitations would basically require the full	4784	Lifting these limitations would basically require the full
4283	re-implementation of the I/O system. If you are into these kinds of	4785	re-implementation of the I/O system. If you are into this kind of thing,
4284	things, then note that glib does exactly that for you in a very portable	4786	then note that glib does exactly that for you in a very portable way (note
4285	way (note also that glib is the slowest event library known to man).	4787	also that glib is the slowest event library known to man).
4286		4788
4287	There is no supported compilation method available on windows except	4789	There is no supported compilation method available on windows except
4288	embedding it into other applications.	4790	embedding it into other applications.
4289		4791
4290	Sensible signal handling is officially unsupported by Microsoft - libev	4792	Sensible signal handling is officially unsupported by Microsoft - libev
…		…
4318	you do I<not> compile the F<ev.c> or any other embedded source files!):	4820	you do I<not> compile the F<ev.c> or any other embedded source files!):
4319		4821
4320	#include "evwrap.h"	4822	#include "evwrap.h"
4321	#include "ev.c"	4823	#include "ev.c"
4322		4824
4323	=over 4
4324
4325	=item The winsocket select function	4825	=head3 The winsocket C<select> function
4326		4826
4327	The winsocket C<select> function doesn't follow POSIX in that it	4827	The winsocket C<select> function doesn't follow POSIX in that it
4328	requires socket I<handles> and not socket I<file descriptors> (it is	4828	requires socket I<handles> and not socket I<file descriptors> (it is
4329	also extremely buggy). This makes select very inefficient, and also	4829	also extremely buggy). This makes select very inefficient, and also
4330	requires a mapping from file descriptors to socket handles (the Microsoft	4830	requires a mapping from file descriptors to socket handles (the Microsoft
…		…
4339	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */	4839	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
4340		4840
4341	Note that winsockets handling of fd sets is O(n), so you can easily get a	4841	Note that winsockets handling of fd sets is O(n), so you can easily get a
4342	complexity in the O(n²) range when using win32.	4842	complexity in the O(n²) range when using win32.
4343		4843
4344	=item Limited number of file descriptors	4844	=head3 Limited number of file descriptors
4345		4845
4346	Windows has numerous arbitrary (and low) limits on things.	4846	Windows has numerous arbitrary (and low) limits on things.
4347		4847
4348	Early versions of winsocket's select only supported waiting for a maximum	4848	Early versions of winsocket's select only supported waiting for a maximum
4349	of C<64> handles (probably owning to the fact that all windows kernels	4849	of C<64> handles (probably owning to the fact that all windows kernels
…		…
4364	runtime libraries. This might get you to about C<512> or C<2048> sockets	4864	runtime libraries. This might get you to about C<512> or C<2048> sockets
4365	(depending on windows version and/or the phase of the moon). To get more,	4865	(depending on windows version and/or the phase of the moon). To get more,
4366	you need to wrap all I/O functions and provide your own fd management, but	4866	you need to wrap all I/O functions and provide your own fd management, but
4367	the cost of calling select (O(n²)) will likely make this unworkable.	4867	the cost of calling select (O(n²)) will likely make this unworkable.
4368		4868
4369	=back
4370
4371	=head2 PORTABILITY REQUIREMENTS	4869	=head2 PORTABILITY REQUIREMENTS
4372		4870
4373	In addition to a working ISO-C implementation and of course the	4871	In addition to a working ISO-C implementation and of course the
4374	backend-specific APIs, libev relies on a few additional extensions:	4872	backend-specific APIs, libev relies on a few additional extensions:
4375		4873
…		…
4381	Libev assumes not only that all watcher pointers have the same internal	4879	Libev assumes not only that all watcher pointers have the same internal
4382	structure (guaranteed by POSIX but not by ISO C for example), but it also	4880	structure (guaranteed by POSIX but not by ISO C for example), but it also
4383	assumes that the same (machine) code can be used to call any watcher	4881	assumes that the same (machine) code can be used to call any watcher
4384	callback: The watcher callbacks have different type signatures, but libev	4882	callback: The watcher callbacks have different type signatures, but libev
4385	calls them using an C<ev_watcher *> internally.	4883	calls them using an C<ev_watcher *> internally.
		4884
		4885	=item pointer accesses must be thread-atomic
		4886
		4887	Accessing a pointer value must be atomic, it must both be readable and
		4888	writable in one piece - this is the case on all current architectures.
4386		4889
4387	=item C<sig_atomic_t volatile> must be thread-atomic as well	4890	=item C<sig_atomic_t volatile> must be thread-atomic as well
4388		4891
4389	The type C<sig_atomic_t volatile> (or whatever is defined as	4892	The type C<sig_atomic_t volatile> (or whatever is defined as
4390	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different	4893	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different
…		…
4413	watchers.	4916	watchers.
4414		4917
4415	=item C<double> must hold a time value in seconds with enough accuracy	4918	=item C<double> must hold a time value in seconds with enough accuracy
4416		4919
4417	The type C<double> is used to represent timestamps. It is required to	4920	The type C<double> is used to represent timestamps. It is required to
4418	have at least 51 bits of mantissa (and 9 bits of exponent), which is good	4921	have at least 51 bits of mantissa (and 9 bits of exponent), which is
4419	enough for at least into the year 4000. This requirement is fulfilled by	4922	good enough for at least into the year 4000 with millisecond accuracy
		4923	(the design goal for libev). This requirement is overfulfilled by
4420	implementations implementing IEEE 754, which is basically all existing	4924	implementations using IEEE 754, which is basically all existing ones. With
4421	ones. With IEEE 754 doubles, you get microsecond accuracy until at least	4925	IEEE 754 doubles, you get microsecond accuracy until at least 2200.
4422	2200.
4423		4926
4424	=back	4927	=back
4425		4928
4426	If you know of other additional requirements drop me a note.	4929	If you know of other additional requirements drop me a note.
4427		4930
…		…
4495	involves iterating over all running async watchers or all signal numbers.	4998	involves iterating over all running async watchers or all signal numbers.
4496		4999
4497	=back	5000	=back
4498		5001
4499		5002
		5003	=head1 PORTING FROM LIBEV 3.X TO 4.X
		5004
		5005	The major version 4 introduced some incompatible changes to the API.
		5006
		5007	At the moment, the C<ev.h> header file provides compatibility definitions
		5008	for all changes, so most programs should still compile. The compatibility
		5009	layer might be removed in later versions of libev, so better update to the
		5010	new API early than late.
		5011
		5012	=over 4
		5013
		5014	=item C<EV_COMPAT3> backwards compatibility mechanism
		5015
		5016	The backward compatibility mechanism can be controlled by
		5017	C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING>
		5018	section.
		5019
		5020	=item C<ev_default_destroy> and C<ev_default_fork> have been removed
		5021
		5022	These calls can be replaced easily by their C<ev_loop_xxx> counterparts:
		5023
		5024	ev_loop_destroy (EV_DEFAULT_UC);
		5025	ev_loop_fork (EV_DEFAULT);
		5026
		5027	=item function/symbol renames
		5028
		5029	A number of functions and symbols have been renamed:
		5030
		5031	ev_loop => ev_run
		5032	EVLOOP_NONBLOCK => EVRUN_NOWAIT
		5033	EVLOOP_ONESHOT => EVRUN_ONCE
		5034
		5035	ev_unloop => ev_break
		5036	EVUNLOOP_CANCEL => EVBREAK_CANCEL
		5037	EVUNLOOP_ONE => EVBREAK_ONE
		5038	EVUNLOOP_ALL => EVBREAK_ALL
		5039
		5040	EV_TIMEOUT => EV_TIMER
		5041
		5042	ev_loop_count => ev_iteration
		5043	ev_loop_depth => ev_depth
		5044	ev_loop_verify => ev_verify
		5045
		5046	Most functions working on C<struct ev_loop> objects don't have an
		5047	C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and
		5048	associated constants have been renamed to not collide with the C<struct
		5049	ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme
		5050	as all other watcher types. Note that C<ev_loop_fork> is still called
		5051	C<ev_loop_fork> because it would otherwise clash with the C<ev_fork>
		5052	typedef.
		5053
		5054	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>
		5055
		5056	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different
		5057	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile
		5058	and work, but the library code will of course be larger.
		5059
		5060	=back
		5061
		5062
4500	=head1 GLOSSARY	5063	=head1 GLOSSARY
4501		5064
4502	=over 4	5065	=over 4
4503		5066
4504	=item active	5067	=item active
4505		5068
4506	A watcher is active as long as it has been started (has been attached to	5069	A watcher is active as long as it has been started and not yet stopped.
4507	an event loop) but not yet stopped (disassociated from the event loop).	5070	See L<WATCHER STATES> for details.
4508		5071
4509	=item application	5072	=item application
4510		5073
4511	In this document, an application is whatever is using libev.	5074	In this document, an application is whatever is using libev.
		5075
		5076	=item backend
		5077
		5078	The part of the code dealing with the operating system interfaces.
4512		5079
4513	=item callback	5080	=item callback
4514		5081
4515	The address of a function that is called when some event has been	5082	The address of a function that is called when some event has been
4516	detected. Callbacks are being passed the event loop, the watcher that	5083	detected. Callbacks are being passed the event loop, the watcher that
4517	received the event, and the actual event bitset.	5084	received the event, and the actual event bitset.
4518		5085
4519	=item callback invocation	5086	=item callback/watcher invocation
4520		5087
4521	The act of calling the callback associated with a watcher.	5088	The act of calling the callback associated with a watcher.
4522		5089
4523	=item event	5090	=item event
4524		5091
4525	A change of state of some external event, such as data now being available	5092	A change of state of some external event, such as data now being available
4526	for reading on a file descriptor, time having passed or simply not having	5093	for reading on a file descriptor, time having passed or simply not having
4527	any other events happening anymore.	5094	any other events happening anymore.
4528		5095
4529	In libev, events are represented as single bits (such as C<EV_READ> or	5096	In libev, events are represented as single bits (such as C<EV_READ> or
4530	C<EV_TIMEOUT>).	5097	C<EV_TIMER>).
4531		5098
4532	=item event library	5099	=item event library
4533		5100
4534	A software package implementing an event model and loop.	5101	A software package implementing an event model and loop.
4535		5102
…		…
4543	The model used to describe how an event loop handles and processes	5110	The model used to describe how an event loop handles and processes
4544	watchers and events.	5111	watchers and events.
4545		5112
4546	=item pending	5113	=item pending
4547		5114
4548	A watcher is pending as soon as the corresponding event has been detected,	5115	A watcher is pending as soon as the corresponding event has been
4549	and stops being pending as soon as the watcher will be invoked or its	5116	detected. See L<WATCHER STATES> for details.
4550	pending status is explicitly cleared by the application.
4551
4552	A watcher can be pending, but not active. Stopping a watcher also clears
4553	its pending status.
4554		5117
4555	=item real time	5118	=item real time
4556		5119
4557	The physical time that is observed. It is apparently strictly monotonic :)	5120	The physical time that is observed. It is apparently strictly monotonic :)
4558		5121
…		…
4565	=item watcher	5128	=item watcher
4566		5129
4567	A data structure that describes interest in certain events. Watchers need	5130	A data structure that describes interest in certain events. Watchers need
4568	to be started (attached to an event loop) before they can receive events.	5131	to be started (attached to an event loop) before they can receive events.
4569		5132
4570	=item watcher invocation
4571
4572	The act of calling the callback associated with a watcher.
4573
4574	=back	5133	=back
4575		5134
4576	=head1 AUTHOR	5135	=head1 AUTHOR
4577		5136
4578	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson.	5137	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael
		5138	Magnusson and Emanuele Giaquinta.
4579		5139

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