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…		…
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
…		…
98	=head2 FEATURES	106	=head2 FEATURES
99		107
100	Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the	108	Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the
101	BSD-specific C<kqueue> and the Solaris-specific event port mechanisms	109	BSD-specific C<kqueue> and the Solaris-specific event port mechanisms
102	for file descriptor events (C<ev_io>), the Linux C<inotify> interface	110	for file descriptor events (C<ev_io>), the Linux C<inotify> interface
103	(for C<ev_stat>), relative timers (C<ev_timer>), absolute timers	111	(for C<ev_stat>), Linux eventfd/signalfd (for faster and cleaner
104	with customised rescheduling (C<ev_periodic>), synchronous signals	112	inter-thread wakeup (C<ev_async>)/signal handling (C<ev_signal>)) relative
105	(C<ev_signal>), process status change events (C<ev_child>), and event	113	timers (C<ev_timer>), absolute timers with customised rescheduling
106	watchers dealing with the event loop mechanism itself (C<ev_idle>,	114	(C<ev_periodic>), synchronous signals (C<ev_signal>), process status
107	C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as	115	change events (C<ev_child>), and event watchers dealing with the event
108	file watchers (C<ev_stat>) and even limited support for fork events	116	loop mechanism itself (C<ev_idle>, C<ev_embed>, C<ev_prepare> and
109	(C<ev_fork>).	117	C<ev_check> watchers) as well as file watchers (C<ev_stat>) and even
		118	limited support for fork events (C<ev_fork>).
110		119
111	It also is quite fast (see this	120	It also is quite fast (see this
112	L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent	121	L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent
113	for example).	122	for example).
114		123
…		…
117	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)
118	configuration will be described, which supports multiple event loops. For	127	configuration will be described, which supports multiple event loops. For
119	more info about various configuration options please have a look at	128	more info about various configuration options please have a look at
120	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
121	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
122	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
123	this argument.	132	this argument.
124		133
125	=head2 TIME REPRESENTATION	134	=head2 TIME REPRESENTATION
126		135
127	Libev represents time as a single floating point number, representing	136	Libev represents time as a single floating point number, representing
128	the (fractional) number of seconds since the (POSIX) epoch (somewhere	137	the (fractional) number of seconds since the (POSIX) epoch (in practice
129	near the beginning of 1970, details are complicated, don't ask). This	138	somewhere near the beginning of 1970, details are complicated, don't
130	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
131	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
132	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
133	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
134	throughout libev.	144	time differences (e.g. delays) throughout libev.
135		145
136	=head1 ERROR HANDLING	146	=head1 ERROR HANDLING
137		147
138	Libev knows three classes of errors: operating system errors, usage errors	148	Libev knows three classes of errors: operating system errors, usage errors
139	and internal errors (bugs).	149	and internal errors (bugs).
…		…
163		173
164	=item ev_tstamp ev_time ()	174	=item ev_tstamp ev_time ()
165		175
166	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
167	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
168	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>.
169		180
170	=item ev_sleep (ev_tstamp interval)	181	=item ev_sleep (ev_tstamp interval)
171		182
172	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
173	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
…		…
190	as this indicates an incompatible change. Minor versions are usually	201	as this indicates an incompatible change. Minor versions are usually
191	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
192	not a problem.	203	not a problem.
193		204
194	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
195	version.	206	version (note, however, that this will not detect other ABI mismatches,
		207	such as LFS or reentrancy).
196		208
197	assert (("libev version mismatch",	209	assert (("libev version mismatch",
198	ev_version_major () == EV_VERSION_MAJOR	210	ev_version_major () == EV_VERSION_MAJOR
199	&& ev_version_minor () >= EV_VERSION_MINOR));	211	&& ev_version_minor () >= EV_VERSION_MINOR));
200		212
…		…
211	assert (("sorry, no epoll, no sex",	223	assert (("sorry, no epoll, no sex",
212	ev_supported_backends () & EVBACKEND_EPOLL));	224	ev_supported_backends () & EVBACKEND_EPOLL));
213		225
214	=item unsigned int ev_recommended_backends ()	226	=item unsigned int ev_recommended_backends ()
215		227
216	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
217	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
218	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
219	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
220	(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
221	libev will probe for if you specify no backends explicitly.	234	probe for if you specify no backends explicitly.
222		235
223	=item unsigned int ev_embeddable_backends ()	236	=item unsigned int ev_embeddable_backends ()
224		237
225	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
226	is the theoretical, all-platform, value. To find which backends	239	value is platform-specific but can include backends not available on the
227	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
228	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for	241	the current system, you would need to look at C<ev_embeddable_backends ()
229	recommended ones.	242	& ev_supported_backends ()>, likewise for recommended ones.
230		243
231	See the description of C<ev_embed> watchers for more info.	244	See the description of C<ev_embed> watchers for more info.
232		245
233	=item ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT]	246	=item ev_set_allocator (void *(*cb)(void *ptr, long size))
234		247
235	Sets the allocation function to use (the prototype is similar - the	248	Sets the allocation function to use (the prototype is similar - the
236	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
237	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
238	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
…		…
264	}	277	}
265		278
266	...	279	...
267	ev_set_allocator (persistent_realloc);	280	ev_set_allocator (persistent_realloc);
268		281
269	=item ev_set_syserr_cb (void (*cb)(const char *msg)); [NOT REENTRANT]	282	=item ev_set_syserr_cb (void (*cb)(const char *msg))
270		283
271	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
272	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
273	indicating the system call or subsystem causing the problem. If this	286	indicating the system call or subsystem causing the problem. If this
274	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
…		…
288	...	301	...
289	ev_set_syserr_cb (fatal_error);	302	ev_set_syserr_cb (fatal_error);
290		303
291	=back	304	=back
292		305
293	=head1 FUNCTIONS CONTROLLING THE EVENT LOOP	306	=head1 FUNCTIONS CONTROLLING EVENT LOOPS
294		307
295	An event loop is described by a C<struct ev_loop *> (the C<struct>	308	An event loop is described by a C<struct ev_loop *> (the C<struct> is
296	is I<not> optional in this case, as there is also an C<ev_loop>	309	I<not> optional in this case unless libev 3 compatibility is disabled, as
297	I<function>).	310	libev 3 had an C<ev_loop> function colliding with the struct name).
298		311
299	The library knows two types of such loops, the I<default> loop, which	312	The library knows two types of such loops, the I<default> loop, which
300	supports signals and child events, and dynamically created loops which do	313	supports child process events, and dynamically created event loops which
301	not.	314	do not.
302		315
303	=over 4	316	=over 4
304		317
305	=item struct ev_loop *ev_default_loop (unsigned int flags)	318	=item struct ev_loop *ev_default_loop (unsigned int flags)
306		319
307	This will initialise the default event loop if it hasn't been initialised	320	This returns the "default" event loop object, which is what you should
308	yet and return it. If the default loop could not be initialised, returns	321	normally use when you just need "the event loop". Event loop objects and
309	false. If it already was initialised it simply returns it (and ignores the	322	the C<flags> parameter are described in more detail in the entry for
310	flags. If that is troubling you, check C<ev_backend ()> afterwards).	323	C<ev_loop_new>.
		324
		325	If the default loop is already initialised then this function simply
		326	returns it (and ignores the flags. If that is troubling you, check
		327	C<ev_backend ()> afterwards). Otherwise it will create it with the given
		328	flags, which should almost always be C<0>, unless the caller is also the
		329	one calling C<ev_run> or otherwise qualifies as "the main program".
311		330
312	If you don't know what event loop to use, use the one returned from this	331	If you don't know what event loop to use, use the one returned from this
313	function.	332	function (or via the C<EV_DEFAULT> macro).
314		333
315	Note that this function is I<not> thread-safe, so if you want to use it	334	Note that this function is I<not> thread-safe, so if you want to use it
316	from multiple threads, you have to lock (note also that this is unlikely,	335	from multiple threads, you have to employ some kind of mutex (note also
317	as loops cannot be shared easily between threads anyway).	336	that this case is unlikely, as loops cannot be shared easily between
		337	threads anyway).
318		338
319	The default loop is the only loop that can handle C<ev_signal> and	339	The default loop is the only loop that can handle C<ev_child> watchers,
320	C<ev_child> watchers, and to do this, it always registers a handler	340	and to do this, it always registers a handler for C<SIGCHLD>. If this is
321	for C<SIGCHLD>. If this is a problem for your application you can either	341	a problem for your application you can either create a dynamic loop with
322	create a dynamic loop with C<ev_loop_new> that doesn't do that, or you	342	C<ev_loop_new> which doesn't do that, or you can simply overwrite the
323	can simply overwrite the C<SIGCHLD> signal handler I<after> calling	343	C<SIGCHLD> signal handler I<after> calling C<ev_default_init>.
324	C<ev_default_init>.	344
		345	Example: This is the most typical usage.
		346
		347	if (!ev_default_loop (0))
		348	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
		349
		350	Example: Restrict libev to the select and poll backends, and do not allow
		351	environment settings to be taken into account:
		352
		353	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
		354
		355	=item struct ev_loop *ev_loop_new (unsigned int flags)
		356
		357	This will create and initialise a new event loop object. If the loop
		358	could not be initialised, returns false.
		359
		360	This function is thread-safe, and one common way to use libev with
		361	threads is indeed to create one loop per thread, and using the default
		362	loop in the "main" or "initial" thread.
325		363
326	The flags argument can be used to specify special behaviour or specific	364	The flags argument can be used to specify special behaviour or specific
327	backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>).	365	backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>).
328		366
329	The following flags are supported:	367	The following flags are supported:
…		…
344	useful to try out specific backends to test their performance, or to work	382	useful to try out specific backends to test their performance, or to work
345	around bugs.	383	around bugs.
346		384
347	=item C<EVFLAG_FORKCHECK>	385	=item C<EVFLAG_FORKCHECK>
348		386
349	Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after	387	Instead of calling C<ev_loop_fork> manually after a fork, you can also
350	a fork, you can also make libev check for a fork in each iteration by	388	make libev check for a fork in each iteration by enabling this flag.
351	enabling this flag.
352		389
353	This works by calling C<getpid ()> on every iteration of the loop,	390	This works by calling C<getpid ()> on every iteration of the loop,
354	and thus this might slow down your event loop if you do a lot of loop	391	and thus this might slow down your event loop if you do a lot of loop
355	iterations and little real work, but is usually not noticeable (on my	392	iterations and little real work, but is usually not noticeable (on my
356	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence	393	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence
…		…
362	flag.	399	flag.
363		400
364	This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS>	401	This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS>
365	environment variable.	402	environment variable.
366		403
		404	=item C<EVFLAG_NOINOTIFY>
		405
		406	When this flag is specified, then libev will not attempt to use the
		407	I<inotify> API for its C<ev_stat> watchers. Apart from debugging and
		408	testing, this flag can be useful to conserve inotify file descriptors, as
		409	otherwise each loop using C<ev_stat> watchers consumes one inotify handle.
		410
		411	=item C<EVFLAG_SIGNALFD>
		412
		413	When this flag is specified, then libev will attempt to use the
		414	I<signalfd> API for its C<ev_signal> (and C<ev_child>) watchers. This API
		415	delivers signals synchronously, which makes it both faster and might make
		416	it possible to get the queued signal data. It can also simplify signal
		417	handling with threads, as long as you properly block signals in your
		418	threads that are not interested in handling them.
		419
		420	Signalfd will not be used by default as this changes your signal mask, and
		421	there are a lot of shoddy libraries and programs (glib's threadpool for
		422	example) that can't properly initialise their signal masks.
		423
367	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	424	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
368		425
369	This is your standard select(2) backend. Not I<completely> standard, as	426	This is your standard select(2) backend. Not I<completely> standard, as
370	libev tries to roll its own fd_set with no limits on the number of fds,	427	libev tries to roll its own fd_set with no limits on the number of fds,
371	but if that fails, expect a fairly low limit on the number of fds when	428	but if that fails, expect a fairly low limit on the number of fds when
…		…
395	This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and	452	This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and
396	C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>.	453	C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>.
397		454
398	=item C<EVBACKEND_EPOLL> (value 4, Linux)	455	=item C<EVBACKEND_EPOLL> (value 4, Linux)
399		456
		457	Use the linux-specific epoll(7) interface (for both pre- and post-2.6.9
		458	kernels).
		459
400	For few fds, this backend is a bit little slower than poll and select,	460	For few fds, this backend is a bit little slower than poll and select,
401	but it scales phenomenally better. While poll and select usually scale	461	but it scales phenomenally better. While poll and select usually scale
402	like O(total_fds) where n is the total number of fds (or the highest fd),	462	like O(total_fds) where n is the total number of fds (or the highest fd),
403	epoll scales either O(1) or O(active_fds).	463	epoll scales either O(1) or O(active_fds).
404		464
405	The epoll mechanism deserves honorable mention as the most misdesigned	465	The epoll mechanism deserves honorable mention as the most misdesigned
406	of the more advanced event mechanisms: mere annoyances include silently	466	of the more advanced event mechanisms: mere annoyances include silently
407	dropping file descriptors, requiring a system call per change per file	467	dropping file descriptors, requiring a system call per change per file
408	descriptor (and unnecessary guessing of parameters), problems with dup and	468	descriptor (and unnecessary guessing of parameters), problems with dup,
		469	returning before the timeout value, resulting in additional iterations
		470	(and only giving 5ms accuracy while select on the same platform gives
409	so on. The biggest issue is fork races, however - if a program forks then	471	0.1ms) and so on. The biggest issue is fork races, however - if a program
410	I<both> parent and child process have to recreate the epoll set, which can	472	forks then I<both> parent and child process have to recreate the epoll
411	take considerable time (one syscall per file descriptor) and is of course	473	set, which can take considerable time (one syscall per file descriptor)
412	hard to detect.	474	and is of course hard to detect.
413		475
414	Epoll is also notoriously buggy - embedding epoll fds I<should> work, but	476	Epoll is also notoriously buggy - embedding epoll fds I<should> work, but
415	of course I<doesn't>, and epoll just loves to report events for totally	477	of course I<doesn't>, and epoll just loves to report events for totally
416	I<different> file descriptors (even already closed ones, so one cannot	478	I<different> file descriptors (even already closed ones, so one cannot
417	even remove them from the set) than registered in the set (especially	479	even remove them from the set) than registered in the set (especially
418	on SMP systems). Libev tries to counter these spurious notifications by	480	on SMP systems). Libev tries to counter these spurious notifications by
419	employing an additional generation counter and comparing that against the	481	employing an additional generation counter and comparing that against the
420	events to filter out spurious ones, recreating the set when required.	482	events to filter out spurious ones, recreating the set when required. Last
		483	not least, it also refuses to work with some file descriptors which work
		484	perfectly fine with C<select> (files, many character devices...).
		485
		486	Epoll is truly the train wreck analog among event poll mechanisms.
421		487
422	While stopping, setting and starting an I/O watcher in the same iteration	488	While stopping, setting and starting an I/O watcher in the same iteration
423	will result in some caching, there is still a system call per such	489	will result in some caching, there is still a system call per such
424	incident (because the same I<file descriptor> could point to a different	490	incident (because the same I<file descriptor> could point to a different
425	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed	491	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed
…		…
518		584
519	It is definitely not recommended to use this flag.	585	It is definitely not recommended to use this flag.
520		586
521	=back	587	=back
522		588
523	If one or more of these are or'ed into the flags value, then only these	589	If one or more of the backend flags are or'ed into the flags value,
524	backends will be tried (in the reverse order as listed here). If none are	590	then only these backends will be tried (in the reverse order as listed
525	specified, all backends in C<ev_recommended_backends ()> will be tried.	591	here). If none are specified, all backends in C<ev_recommended_backends
526		592	()> will be tried.
527	Example: This is the most typical usage.
528
529	if (!ev_default_loop (0))
530	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
531
532	Example: Restrict libev to the select and poll backends, and do not allow
533	environment settings to be taken into account:
534
535	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
536
537	Example: Use whatever libev has to offer, but make sure that kqueue is
538	used if available (warning, breaks stuff, best use only with your own
539	private event loop and only if you know the OS supports your types of
540	fds):
541
542	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
543
544	=item struct ev_loop *ev_loop_new (unsigned int flags)
545
546	Similar to C<ev_default_loop>, but always creates a new event loop that is
547	always distinct from the default loop. Unlike the default loop, it cannot
548	handle signal and child watchers, and attempts to do so will be greeted by
549	undefined behaviour (or a failed assertion if assertions are enabled).
550
551	Note that this function I<is> thread-safe, and the recommended way to use
552	libev with threads is indeed to create one loop per thread, and using the
553	default loop in the "main" or "initial" thread.
554		593
555	Example: Try to create a event loop that uses epoll and nothing else.	594	Example: Try to create a event loop that uses epoll and nothing else.
556		595
557	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	596	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
558	if (!epoller)	597	if (!epoller)
559	fatal ("no epoll found here, maybe it hides under your chair");	598	fatal ("no epoll found here, maybe it hides under your chair");
560		599
		600	Example: Use whatever libev has to offer, but make sure that kqueue is
		601	used if available.
		602
		603	struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE);
		604
561	=item ev_default_destroy ()	605	=item ev_loop_destroy (loop)
562		606
563	Destroys the default loop again (frees all memory and kernel state	607	Destroys an event loop object (frees all memory and kernel state
564	etc.). None of the active event watchers will be stopped in the normal	608	etc.). None of the active event watchers will be stopped in the normal
565	sense, so e.g. C<ev_is_active> might still return true. It is your	609	sense, so e.g. C<ev_is_active> might still return true. It is your
566	responsibility to either stop all watchers cleanly yourself I<before>	610	responsibility to either stop all watchers cleanly yourself I<before>
567	calling this function, or cope with the fact afterwards (which is usually	611	calling this function, or cope with the fact afterwards (which is usually
568	the easiest thing, you can just ignore the watchers and/or C<free ()> them	612	the easiest thing, you can just ignore the watchers and/or C<free ()> them
…		…
570		614
571	Note that certain global state, such as signal state (and installed signal	615	Note that certain global state, such as signal state (and installed signal
572	handlers), will not be freed by this function, and related watchers (such	616	handlers), will not be freed by this function, and related watchers (such
573	as signal and child watchers) would need to be stopped manually.	617	as signal and child watchers) would need to be stopped manually.
574		618
575	In general it is not advisable to call this function except in the	619	This function is normally used on loop objects allocated by
576	rare occasion where you really need to free e.g. the signal handling	620	C<ev_loop_new>, but it can also be used on the default loop returned by
		621	C<ev_default_loop>, in which case it is not thread-safe.
		622
		623	Note that it is not advisable to call this function on the default loop
		624	except in the rare occasion where you really need to free its resources.
577	pipe fds. If you need dynamically allocated loops it is better to use	625	If you need dynamically allocated loops it is better to use C<ev_loop_new>
578	C<ev_loop_new> and C<ev_loop_destroy>).	626	and C<ev_loop_destroy>.
579		627
580	=item ev_loop_destroy (loop)	628	=item ev_loop_fork (loop)
581		629
582	Like C<ev_default_destroy>, but destroys an event loop created by an
583	earlier call to C<ev_loop_new>.
584
585	=item ev_default_fork ()
586
587	This function sets a flag that causes subsequent C<ev_loop> iterations	630	This function sets a flag that causes subsequent C<ev_run> iterations to
588	to reinitialise the kernel state for backends that have one. Despite the	631	reinitialise the kernel state for backends that have one. Despite the
589	name, you can call it anytime, but it makes most sense after forking, in	632	name, you can call it anytime, but it makes most sense after forking, in
590	the child process (or both child and parent, but that again makes little	633	the child process. You I<must> call it (or use C<EVFLAG_FORKCHECK>) in the
591	sense). You I<must> call it in the child before using any of the libev	634	child before resuming or calling C<ev_run>.
592	functions, and it will only take effect at the next C<ev_loop> iteration.	635
		636	Again, you I<have> to call it on I<any> loop that you want to re-use after
		637	a fork, I<even if you do not plan to use the loop in the parent>. This is
		638	because some kernel interfaces *cough* I<kqueue> *cough* do funny things
		639	during fork.
593		640
594	On the other hand, you only need to call this function in the child	641	On the other hand, you only need to call this function in the child
595	process if and only if you want to use the event library in the child. If	642	process if and only if you want to use the event loop in the child. If
596	you just fork+exec, you don't have to call it at all.	643	you just fork+exec or create a new loop in the child, you don't have to
		644	call it at all (in fact, C<epoll> is so badly broken that it makes a
		645	difference, but libev will usually detect this case on its own and do a
		646	costly reset of the backend).
597		647
598	The function itself is quite fast and it's usually not a problem to call	648	The function itself is quite fast and it's usually not a problem to call
599	it just in case after a fork. To make this easy, the function will fit in	649	it just in case after a fork.
600	quite nicely into a call to C<pthread_atfork>:
601		650
		651	Example: Automate calling C<ev_loop_fork> on the default loop when
		652	using pthreads.
		653
		654	static void
		655	post_fork_child (void)
		656	{
		657	ev_loop_fork (EV_DEFAULT);
		658	}
		659
		660	...
602	pthread_atfork (0, 0, ev_default_fork);	661	pthread_atfork (0, 0, post_fork_child);
603
604	=item ev_loop_fork (loop)
605
606	Like C<ev_default_fork>, but acts on an event loop created by
607	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
608	after fork that you want to re-use in the child, and how you do this is
609	entirely your own problem.
610		662
611	=item int ev_is_default_loop (loop)	663	=item int ev_is_default_loop (loop)
612		664
613	Returns true when the given loop is, in fact, the default loop, and false	665	Returns true when the given loop is, in fact, the default loop, and false
614	otherwise.	666	otherwise.
615		667
616	=item unsigned int ev_loop_count (loop)	668	=item unsigned int ev_iteration (loop)
617		669
618	Returns the count of loop iterations for the loop, which is identical to	670	Returns the current iteration count for the event loop, which is identical
619	the number of times libev did poll for new events. It starts at C<0> and	671	to the number of times libev did poll for new events. It starts at C<0>
620	happily wraps around with enough iterations.	672	and happily wraps around with enough iterations.
621		673
622	This value can sometimes be useful as a generation counter of sorts (it	674	This value can sometimes be useful as a generation counter of sorts (it
623	"ticks" the number of loop iterations), as it roughly corresponds with	675	"ticks" the number of loop iterations), as it roughly corresponds with
624	C<ev_prepare> and C<ev_check> calls.	676	C<ev_prepare> and C<ev_check> calls - and is incremented between the
		677	prepare and check phases.
625		678
626	=item unsigned int ev_loop_depth (loop)	679	=item unsigned int ev_depth (loop)
627		680
628	Returns the number of times C<ev_loop> was entered minus the number of	681	Returns the number of times C<ev_run> was entered minus the number of
629	times C<ev_loop> was exited, in other words, the recursion depth.	682	times C<ev_run> was exited normally, in other words, the recursion depth.
630		683
631	Outside C<ev_loop>, this number is zero. In a callback, this number is	684	Outside C<ev_run>, this number is zero. In a callback, this number is
632	C<1>, unless C<ev_loop> was invoked recursively (or from another thread),	685	C<1>, unless C<ev_run> was invoked recursively (or from another thread),
633	in which case it is higher.	686	in which case it is higher.
634		687
635	Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread	688	Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread,
636	etc.), doesn't count as exit.	689	throwing an exception etc.), doesn't count as "exit" - consider this
		690	as a hint to avoid such ungentleman-like behaviour unless it's really
		691	convenient, in which case it is fully supported.
637		692
638	=item unsigned int ev_backend (loop)	693	=item unsigned int ev_backend (loop)
639		694
640	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	695	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
641	use.	696	use.
…		…
650		705
651	=item ev_now_update (loop)	706	=item ev_now_update (loop)
652		707
653	Establishes the current time by querying the kernel, updating the time	708	Establishes the current time by querying the kernel, updating the time
654	returned by C<ev_now ()> in the progress. This is a costly operation and	709	returned by C<ev_now ()> in the progress. This is a costly operation and
655	is usually done automatically within C<ev_loop ()>.	710	is usually done automatically within C<ev_run ()>.
656		711
657	This function is rarely useful, but when some event callback runs for a	712	This function is rarely useful, but when some event callback runs for a
658	very long time without entering the event loop, updating libev's idea of	713	very long time without entering the event loop, updating libev's idea of
659	the current time is a good idea.	714	the current time is a good idea.
660		715
…		…
662		717
663	=item ev_suspend (loop)	718	=item ev_suspend (loop)
664		719
665	=item ev_resume (loop)	720	=item ev_resume (loop)
666		721
667	These two functions suspend and resume a loop, for use when the loop is	722	These two functions suspend and resume an event loop, for use when the
668	not used for a while and timeouts should not be processed.	723	loop is not used for a while and timeouts should not be processed.
669		724
670	A typical use case would be an interactive program such as a game: When	725	A typical use case would be an interactive program such as a game: When
671	the user presses C<^Z> to suspend the game and resumes it an hour later it	726	the user presses C<^Z> to suspend the game and resumes it an hour later it
672	would be best to handle timeouts as if no time had actually passed while	727	would be best to handle timeouts as if no time had actually passed while
673	the program was suspended. This can be achieved by calling C<ev_suspend>	728	the program was suspended. This can be achieved by calling C<ev_suspend>
…		…
675	C<ev_resume> directly afterwards to resume timer processing.	730	C<ev_resume> directly afterwards to resume timer processing.
676		731
677	Effectively, all C<ev_timer> watchers will be delayed by the time spend	732	Effectively, all C<ev_timer> watchers will be delayed by the time spend
678	between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers	733	between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers
679	will be rescheduled (that is, they will lose any events that would have	734	will be rescheduled (that is, they will lose any events that would have
680	occured while suspended).	735	occurred while suspended).
681		736
682	After calling C<ev_suspend> you B<must not> call I<any> function on the	737	After calling C<ev_suspend> you B<must not> call I<any> function on the
683	given loop other than C<ev_resume>, and you B<must not> call C<ev_resume>	738	given loop other than C<ev_resume>, and you B<must not> call C<ev_resume>
684	without a previous call to C<ev_suspend>.	739	without a previous call to C<ev_suspend>.
685		740
686	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the	741	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the
687	event loop time (see C<ev_now_update>).	742	event loop time (see C<ev_now_update>).
688		743
689	=item ev_loop (loop, int flags)	744	=item ev_run (loop, int flags)
690		745
691	Finally, this is it, the event handler. This function usually is called	746	Finally, this is it, the event handler. This function usually is called
692	after you initialised all your watchers and you want to start handling	747	after you have initialised all your watchers and you want to start
693	events.	748	handling events. It will ask the operating system for any new events, call
		749	the watcher callbacks, an then repeat the whole process indefinitely: This
		750	is why event loops are called I<loops>.
694		751
695	If the flags argument is specified as C<0>, it will not return until	752	If the flags argument is specified as C<0>, it will keep handling events
696	either no event watchers are active anymore or C<ev_unloop> was called.	753	until either no event watchers are active anymore or C<ev_break> was
		754	called.
697		755
698	Please note that an explicit C<ev_unloop> is usually better than	756	Please note that an explicit C<ev_break> is usually better than
699	relying on all watchers to be stopped when deciding when a program has	757	relying on all watchers to be stopped when deciding when a program has
700	finished (especially in interactive programs), but having a program	758	finished (especially in interactive programs), but having a program
701	that automatically loops as long as it has to and no longer by virtue	759	that automatically loops as long as it has to and no longer by virtue
702	of relying on its watchers stopping correctly, that is truly a thing of	760	of relying on its watchers stopping correctly, that is truly a thing of
703	beauty.	761	beauty.
704		762
		763	This function is also I<mostly> exception-safe - you can break out of
		764	a C<ev_run> call by calling C<longjmp> in a callback, throwing a C++
		765	exception and so on. This does not decrement the C<ev_depth> value, nor
		766	will it clear any outstanding C<EVBREAK_ONE> breaks.
		767
705	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle	768	A flags value of C<EVRUN_NOWAIT> will look for new events, will handle
706	those events and any already outstanding ones, but will not block your	769	those events and any already outstanding ones, but will not wait and
707	process in case there are no events and will return after one iteration of	770	block your process in case there are no events and will return after one
708	the loop.	771	iteration of the loop. This is sometimes useful to poll and handle new
		772	events while doing lengthy calculations, to keep the program responsive.
709		773
710	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if	774	A flags value of C<EVRUN_ONCE> will look for new events (waiting if
711	necessary) and will handle those and any already outstanding ones. It	775	necessary) and will handle those and any already outstanding ones. It
712	will block your process until at least one new event arrives (which could	776	will block your process until at least one new event arrives (which could
713	be an event internal to libev itself, so there is no guarantee that a	777	be an event internal to libev itself, so there is no guarantee that a
714	user-registered callback will be called), and will return after one	778	user-registered callback will be called), and will return after one
715	iteration of the loop.	779	iteration of the loop.
716		780
717	This is useful if you are waiting for some external event in conjunction	781	This is useful if you are waiting for some external event in conjunction
718	with something not expressible using other libev watchers (i.e. "roll your	782	with something not expressible using other libev watchers (i.e. "roll your
719	own C<ev_loop>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is	783	own C<ev_run>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is
720	usually a better approach for this kind of thing.	784	usually a better approach for this kind of thing.
721		785
722	Here are the gory details of what C<ev_loop> does:	786	Here are the gory details of what C<ev_run> does:
723		787
		788	- Increment loop depth.
		789	- Reset the ev_break status.
724	- Before the first iteration, call any pending watchers.	790	- Before the first iteration, call any pending watchers.
		791	LOOP:
725	* If EVFLAG_FORKCHECK was used, check for a fork.	792	- If EVFLAG_FORKCHECK was used, check for a fork.
726	- If a fork was detected (by any means), queue and call all fork watchers.	793	- If a fork was detected (by any means), queue and call all fork watchers.
727	- Queue and call all prepare watchers.	794	- Queue and call all prepare watchers.
		795	- If ev_break was called, goto FINISH.
728	- If we have been forked, detach and recreate the kernel state	796	- If we have been forked, detach and recreate the kernel state
729	as to not disturb the other process.	797	as to not disturb the other process.
730	- Update the kernel state with all outstanding changes.	798	- Update the kernel state with all outstanding changes.
731	- Update the "event loop time" (ev_now ()).	799	- Update the "event loop time" (ev_now ()).
732	- Calculate for how long to sleep or block, if at all	800	- Calculate for how long to sleep or block, if at all
733	(active idle watchers, EVLOOP_NONBLOCK or not having	801	(active idle watchers, EVRUN_NOWAIT or not having
734	any active watchers at all will result in not sleeping).	802	any active watchers at all will result in not sleeping).
735	- Sleep if the I/O and timer collect interval say so.	803	- Sleep if the I/O and timer collect interval say so.
		804	- Increment loop iteration counter.
736	- Block the process, waiting for any events.	805	- Block the process, waiting for any events.
737	- Queue all outstanding I/O (fd) events.	806	- Queue all outstanding I/O (fd) events.
738	- Update the "event loop time" (ev_now ()), and do time jump adjustments.	807	- Update the "event loop time" (ev_now ()), and do time jump adjustments.
739	- Queue all expired timers.	808	- Queue all expired timers.
740	- Queue all expired periodics.	809	- Queue all expired periodics.
741	- Unless any events are pending now, queue all idle watchers.	810	- Queue all idle watchers with priority higher than that of pending events.
742	- Queue all check watchers.	811	- Queue all check watchers.
743	- Call all queued watchers in reverse order (i.e. check watchers first).	812	- Call all queued watchers in reverse order (i.e. check watchers first).
744	Signals and child watchers are implemented as I/O watchers, and will	813	Signals and child watchers are implemented as I/O watchers, and will
745	be handled here by queueing them when their watcher gets executed.	814	be handled here by queueing them when their watcher gets executed.
746	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	815	- If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT
747	were used, or there are no active watchers, return, otherwise	816	were used, or there are no active watchers, goto FINISH, otherwise
748	continue with step *.	817	continue with step LOOP.
		818	FINISH:
		819	- Reset the ev_break status iff it was EVBREAK_ONE.
		820	- Decrement the loop depth.
		821	- Return.
749		822
750	Example: Queue some jobs and then loop until no events are outstanding	823	Example: Queue some jobs and then loop until no events are outstanding
751	anymore.	824	anymore.
752		825
753	... queue jobs here, make sure they register event watchers as long	826	... queue jobs here, make sure they register event watchers as long
754	... as they still have work to do (even an idle watcher will do..)	827	... as they still have work to do (even an idle watcher will do..)
755	ev_loop (my_loop, 0);	828	ev_run (my_loop, 0);
756	... jobs done or somebody called unloop. yeah!	829	... jobs done or somebody called unloop. yeah!
757		830
758	=item ev_unloop (loop, how)	831	=item ev_break (loop, how)
759		832
760	Can be used to make a call to C<ev_loop> return early (but only after it	833	Can be used to make a call to C<ev_run> return early (but only after it
761	has processed all outstanding events). The C<how> argument must be either	834	has processed all outstanding events). The C<how> argument must be either
762	C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or	835	C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or
763	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.	836	C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return.
764		837
765	This "unloop state" will be cleared when entering C<ev_loop> again.	838	This "break state" will be cleared on the next call to C<ev_run>.
766		839
767	It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls.	840	It is safe to call C<ev_break> from outside any C<ev_run> calls, too, in
		841	which case it will have no effect.
768		842
769	=item ev_ref (loop)	843	=item ev_ref (loop)
770		844
771	=item ev_unref (loop)	845	=item ev_unref (loop)
772		846
773	Ref/unref can be used to add or remove a reference count on the event	847	Ref/unref can be used to add or remove a reference count on the event
774	loop: Every watcher keeps one reference, and as long as the reference	848	loop: Every watcher keeps one reference, and as long as the reference
775	count is nonzero, C<ev_loop> will not return on its own.	849	count is nonzero, C<ev_run> will not return on its own.
776		850
777	If you have a watcher you never unregister that should not keep C<ev_loop>	851	This is useful when you have a watcher that you never intend to
778	from returning, call ev_unref() after starting, and ev_ref() before	852	unregister, but that nevertheless should not keep C<ev_run> from
		853	returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>
779	stopping it.	854	before stopping it.
780		855
781	As an example, libev itself uses this for its internal signal pipe: It	856	As an example, libev itself uses this for its internal signal pipe: It
782	is not visible to the libev user and should not keep C<ev_loop> from	857	is not visible to the libev user and should not keep C<ev_run> from
783	exiting if no event watchers registered by it are active. It is also an	858	exiting if no event watchers registered by it are active. It is also an
784	excellent way to do this for generic recurring timers or from within	859	excellent way to do this for generic recurring timers or from within
785	third-party libraries. Just remember to I<unref after start> and I<ref	860	third-party libraries. Just remember to I<unref after start> and I<ref
786	before stop> (but only if the watcher wasn't active before, or was active	861	before stop> (but only if the watcher wasn't active before, or was active
787	before, respectively. Note also that libev might stop watchers itself	862	before, respectively. Note also that libev might stop watchers itself
788	(e.g. non-repeating timers) in which case you have to C<ev_ref>	863	(e.g. non-repeating timers) in which case you have to C<ev_ref>
789	in the callback).	864	in the callback).
790		865
791	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	866	Example: Create a signal watcher, but keep it from keeping C<ev_run>
792	running when nothing else is active.	867	running when nothing else is active.
793		868
794	ev_signal exitsig;	869	ev_signal exitsig;
795	ev_signal_init (&exitsig, sig_cb, SIGINT);	870	ev_signal_init (&exitsig, sig_cb, SIGINT);
796	ev_signal_start (loop, &exitsig);	871	ev_signal_start (loop, &exitsig);
…		…
841	usually doesn't make much sense to set it to a lower value than C<0.01>,	916	usually doesn't make much sense to set it to a lower value than C<0.01>,
842	as this approaches the timing granularity of most systems. Note that if	917	as this approaches the timing granularity of most systems. Note that if
843	you do transactions with the outside world and you can't increase the	918	you do transactions with the outside world and you can't increase the
844	parallelity, then this setting will limit your transaction rate (if you	919	parallelity, then this setting will limit your transaction rate (if you
845	need to poll once per transaction and the I/O collect interval is 0.01,	920	need to poll once per transaction and the I/O collect interval is 0.01,
846	then you can't do more than 100 transations per second).	921	then you can't do more than 100 transactions per second).
847		922
848	Setting the I<timeout collect interval> can improve the opportunity for	923	Setting the I<timeout collect interval> can improve the opportunity for
849	saving power, as the program will "bundle" timer callback invocations that	924	saving power, as the program will "bundle" timer callback invocations that
850	are "near" in time together, by delaying some, thus reducing the number of	925	are "near" in time together, by delaying some, thus reducing the number of
851	times the process sleeps and wakes up again. Another useful technique to	926	times the process sleeps and wakes up again. Another useful technique to
…		…
856	more often than 100 times per second:	931	more often than 100 times per second:
857		932
858	ev_set_timeout_collect_interval (EV_DEFAULT_UC_ 0.1);	933	ev_set_timeout_collect_interval (EV_DEFAULT_UC_ 0.1);
859	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);	934	ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01);
860		935
		936	=item ev_invoke_pending (loop)
		937
		938	This call will simply invoke all pending watchers while resetting their
		939	pending state. Normally, C<ev_run> does this automatically when required,
		940	but when overriding the invoke callback this call comes handy. This
		941	function can be invoked from a watcher - this can be useful for example
		942	when you want to do some lengthy calculation and want to pass further
		943	event handling to another thread (you still have to make sure only one
		944	thread executes within C<ev_invoke_pending> or C<ev_run> of course).
		945
		946	=item int ev_pending_count (loop)
		947
		948	Returns the number of pending watchers - zero indicates that no watchers
		949	are pending.
		950
		951	=item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))
		952
		953	This overrides the invoke pending functionality of the loop: Instead of
		954	invoking all pending watchers when there are any, C<ev_run> will call
		955	this callback instead. This is useful, for example, when you want to
		956	invoke the actual watchers inside another context (another thread etc.).
		957
		958	If you want to reset the callback, use C<ev_invoke_pending> as new
		959	callback.
		960
		961	=item ev_set_loop_release_cb (loop, void (*release)(EV_P), void (*acquire)(EV_P))
		962
		963	Sometimes you want to share the same loop between multiple threads. This
		964	can be done relatively simply by putting mutex_lock/unlock calls around
		965	each call to a libev function.
		966
		967	However, C<ev_run> can run an indefinite time, so it is not feasible
		968	to wait for it to return. One way around this is to wake up the event
		969	loop via C<ev_break> and C<av_async_send>, another way is to set these
		970	I<release> and I<acquire> callbacks on the loop.
		971
		972	When set, then C<release> will be called just before the thread is
		973	suspended waiting for new events, and C<acquire> is called just
		974	afterwards.
		975
		976	Ideally, C<release> will just call your mutex_unlock function, and
		977	C<acquire> will just call the mutex_lock function again.
		978
		979	While event loop modifications are allowed between invocations of
		980	C<release> and C<acquire> (that's their only purpose after all), no
		981	modifications done will affect the event loop, i.e. adding watchers will
		982	have no effect on the set of file descriptors being watched, or the time
		983	waited. Use an C<ev_async> watcher to wake up C<ev_run> when you want it
		984	to take note of any changes you made.
		985
		986	In theory, threads executing C<ev_run> will be async-cancel safe between
		987	invocations of C<release> and C<acquire>.
		988
		989	See also the locking example in the C<THREADS> section later in this
		990	document.
		991
		992	=item ev_set_userdata (loop, void *data)
		993
		994	=item void *ev_userdata (loop)
		995
		996	Set and retrieve a single C<void *> associated with a loop. When
		997	C<ev_set_userdata> has never been called, then C<ev_userdata> returns
		998	C<0>.
		999
		1000	These two functions can be used to associate arbitrary data with a loop,
		1001	and are intended solely for the C<invoke_pending_cb>, C<release> and
		1002	C<acquire> callbacks described above, but of course can be (ab-)used for
		1003	any other purpose as well.
		1004
861	=item ev_loop_verify (loop)	1005	=item ev_verify (loop)
862		1006
863	This function only does something when C<EV_VERIFY> support has been	1007	This function only does something when C<EV_VERIFY> support has been
864	compiled in, which is the default for non-minimal builds. It tries to go	1008	compiled in, which is the default for non-minimal builds. It tries to go
865	through all internal structures and checks them for validity. If anything	1009	through all internal structures and checks them for validity. If anything
866	is found to be inconsistent, it will print an error message to standard	1010	is found to be inconsistent, it will print an error message to standard
…		…
877		1021
878	In the following description, uppercase C<TYPE> in names stands for the	1022	In the following description, uppercase C<TYPE> in names stands for the
879	watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer	1023	watcher type, e.g. C<ev_TYPE_start> can mean C<ev_timer_start> for timer
880	watchers and C<ev_io_start> for I/O watchers.	1024	watchers and C<ev_io_start> for I/O watchers.
881		1025
882	A watcher is a structure that you create and register to record your	1026	A watcher is an opaque structure that you allocate and register to record
883	interest in some event. For instance, if you want to wait for STDIN to	1027	your interest in some event. To make a concrete example, imagine you want
884	become readable, you would create an C<ev_io> watcher for that:	1028	to wait for STDIN to become readable, you would create an C<ev_io> watcher
		1029	for that:
885		1030
886	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)	1031	static void my_cb (struct ev_loop *loop, ev_io *w, int revents)
887	{	1032	{
888	ev_io_stop (w);	1033	ev_io_stop (w);
889	ev_unloop (loop, EVUNLOOP_ALL);	1034	ev_break (loop, EVBREAK_ALL);
890	}	1035	}
891		1036
892	struct ev_loop *loop = ev_default_loop (0);	1037	struct ev_loop *loop = ev_default_loop (0);
893		1038
894	ev_io stdin_watcher;	1039	ev_io stdin_watcher;
895		1040
896	ev_init (&stdin_watcher, my_cb);	1041	ev_init (&stdin_watcher, my_cb);
897	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	1042	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
898	ev_io_start (loop, &stdin_watcher);	1043	ev_io_start (loop, &stdin_watcher);
899		1044
900	ev_loop (loop, 0);	1045	ev_run (loop, 0);
901		1046
902	As you can see, you are responsible for allocating the memory for your	1047	As you can see, you are responsible for allocating the memory for your
903	watcher structures (and it is I<usually> a bad idea to do this on the	1048	watcher structures (and it is I<usually> a bad idea to do this on the
904	stack).	1049	stack).
905		1050
906	Each watcher has an associated watcher structure (called C<struct ev_TYPE>	1051	Each watcher has an associated watcher structure (called C<struct ev_TYPE>
907	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).	1052	or simply C<ev_TYPE>, as typedefs are provided for all watcher structs).
908		1053
909	Each watcher structure must be initialised by a call to C<ev_init	1054	Each watcher structure must be initialised by a call to C<ev_init (watcher
910	(watcher *, callback)>, which expects a callback to be provided. This	1055	*, callback)>, which expects a callback to be provided. This callback is
911	callback gets invoked each time the event occurs (or, in the case of I/O	1056	invoked each time the event occurs (or, in the case of I/O watchers, each
912	watchers, each time the event loop detects that the file descriptor given	1057	time the event loop detects that the file descriptor given is readable
913	is readable and/or writable).	1058	and/or writable).
914		1059
915	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>	1060	Each watcher type further has its own C<< ev_TYPE_set (watcher *, ...) >>
916	macro to configure it, with arguments specific to the watcher type. There	1061	macro to configure it, with arguments specific to the watcher type. There
917	is also a macro to combine initialisation and setting in one call: C<<	1062	is also a macro to combine initialisation and setting in one call: C<<
918	ev_TYPE_init (watcher *, callback, ...) >>.	1063	ev_TYPE_init (watcher *, callback, ...) >>.
…		…
941	=item C<EV_WRITE>	1086	=item C<EV_WRITE>
942		1087
943	The file descriptor in the C<ev_io> watcher has become readable and/or	1088	The file descriptor in the C<ev_io> watcher has become readable and/or
944	writable.	1089	writable.
945		1090
946	=item C<EV_TIMEOUT>	1091	=item C<EV_TIMER>
947		1092
948	The C<ev_timer> watcher has timed out.	1093	The C<ev_timer> watcher has timed out.
949		1094
950	=item C<EV_PERIODIC>	1095	=item C<EV_PERIODIC>
951		1096
…		…
969		1114
970	=item C<EV_PREPARE>	1115	=item C<EV_PREPARE>
971		1116
972	=item C<EV_CHECK>	1117	=item C<EV_CHECK>
973		1118
974	All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts	1119	All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts
975	to gather new events, and all C<ev_check> watchers are invoked just after	1120	to gather new events, and all C<ev_check> watchers are invoked just after
976	C<ev_loop> has gathered them, but before it invokes any callbacks for any	1121	C<ev_run> has gathered them, but before it invokes any callbacks for any
977	received events. Callbacks of both watcher types can start and stop as	1122	received events. Callbacks of both watcher types can start and stop as
978	many watchers as they want, and all of them will be taken into account	1123	many watchers as they want, and all of them will be taken into account
979	(for example, a C<ev_prepare> watcher might start an idle watcher to keep	1124	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
980	C<ev_loop> from blocking).	1125	C<ev_run> from blocking).
981		1126
982	=item C<EV_EMBED>	1127	=item C<EV_EMBED>
983		1128
984	The embedded event loop specified in the C<ev_embed> watcher needs attention.	1129	The embedded event loop specified in the C<ev_embed> watcher needs attention.
985		1130
986	=item C<EV_FORK>	1131	=item C<EV_FORK>
987		1132
988	The event loop has been resumed in the child process after fork (see	1133	The event loop has been resumed in the child process after fork (see
989	C<ev_fork>).	1134	C<ev_fork>).
		1135
		1136	=item C<EV_CLEANUP>
		1137
		1138	The event loop is about to be destroyed (see C<ev_cleanup>).
990		1139
991	=item C<EV_ASYNC>	1140	=item C<EV_ASYNC>
992		1141
993	The given async watcher has been asynchronously notified (see C<ev_async>).	1142	The given async watcher has been asynchronously notified (see C<ev_async>).
994		1143
…		…
1041		1190
1042	ev_io w;	1191	ev_io w;
1043	ev_init (&w, my_cb);	1192	ev_init (&w, my_cb);
1044	ev_io_set (&w, STDIN_FILENO, EV_READ);	1193	ev_io_set (&w, STDIN_FILENO, EV_READ);
1045		1194
1046	=item C<ev_TYPE_set> (ev_TYPE *, [args])	1195	=item C<ev_TYPE_set> (ev_TYPE *watcher, [args])
1047		1196
1048	This macro initialises the type-specific parts of a watcher. You need to	1197	This macro initialises the type-specific parts of a watcher. You need to
1049	call C<ev_init> at least once before you call this macro, but you can	1198	call C<ev_init> at least once before you call this macro, but you can
1050	call C<ev_TYPE_set> any number of times. You must not, however, call this	1199	call C<ev_TYPE_set> any number of times. You must not, however, call this
1051	macro on a watcher that is active (it can be pending, however, which is a	1200	macro on a watcher that is active (it can be pending, however, which is a
…		…
1064		1213
1065	Example: Initialise and set an C<ev_io> watcher in one step.	1214	Example: Initialise and set an C<ev_io> watcher in one step.
1066		1215
1067	ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ);	1216	ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ);
1068		1217
1069	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)	1218	=item C<ev_TYPE_start> (loop, ev_TYPE *watcher)
1070		1219
1071	Starts (activates) the given watcher. Only active watchers will receive	1220	Starts (activates) the given watcher. Only active watchers will receive
1072	events. If the watcher is already active nothing will happen.	1221	events. If the watcher is already active nothing will happen.
1073		1222
1074	Example: Start the C<ev_io> watcher that is being abused as example in this	1223	Example: Start the C<ev_io> watcher that is being abused as example in this
1075	whole section.	1224	whole section.
1076		1225
1077	ev_io_start (EV_DEFAULT_UC, &w);	1226	ev_io_start (EV_DEFAULT_UC, &w);
1078		1227
1079	=item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher)	1228	=item C<ev_TYPE_stop> (loop, ev_TYPE *watcher)
1080		1229
1081	Stops the given watcher if active, and clears the pending status (whether	1230	Stops the given watcher if active, and clears the pending status (whether
1082	the watcher was active or not).	1231	the watcher was active or not).
1083		1232
1084	It is possible that stopped watchers are pending - for example,	1233	It is possible that stopped watchers are pending - for example,
…		…
1109	=item ev_cb_set (ev_TYPE *watcher, callback)	1258	=item ev_cb_set (ev_TYPE *watcher, callback)
1110		1259
1111	Change the callback. You can change the callback at virtually any time	1260	Change the callback. You can change the callback at virtually any time
1112	(modulo threads).	1261	(modulo threads).
1113		1262
1114	=item ev_set_priority (ev_TYPE *watcher, priority)	1263	=item ev_set_priority (ev_TYPE *watcher, int priority)
1115		1264
1116	=item int ev_priority (ev_TYPE *watcher)	1265	=item int ev_priority (ev_TYPE *watcher)
1117		1266
1118	Set and query the priority of the watcher. The priority is a small	1267	Set and query the priority of the watcher. The priority is a small
1119	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>	1268	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>
…		…
1151	watcher isn't pending it does nothing and returns C<0>.	1300	watcher isn't pending it does nothing and returns C<0>.
1152		1301
1153	Sometimes it can be useful to "poll" a watcher instead of waiting for its	1302	Sometimes it can be useful to "poll" a watcher instead of waiting for its
1154	callback to be invoked, which can be accomplished with this function.	1303	callback to be invoked, which can be accomplished with this function.
1155		1304
		1305	=item ev_feed_event (loop, ev_TYPE *watcher, int revents)
		1306
		1307	Feeds the given event set into the event loop, as if the specified event
		1308	had happened for the specified watcher (which must be a pointer to an
		1309	initialised but not necessarily started event watcher). Obviously you must
		1310	not free the watcher as long as it has pending events.
		1311
		1312	Stopping the watcher, letting libev invoke it, or calling
		1313	C<ev_clear_pending> will clear the pending event, even if the watcher was
		1314	not started in the first place.
		1315
		1316	See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related
		1317	functions that do not need a watcher.
		1318
1156	=back	1319	=back
1157
1158		1320
1159	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	1321	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
1160		1322
1161	Each watcher has, by default, a member C<void *data> that you can change	1323	Each watcher has, by default, a member C<void *data> that you can change
1162	and read at any time: libev will completely ignore it. This can be used	1324	and read at any time: libev will completely ignore it. This can be used
…		…
1218	t2_cb (EV_P_ ev_timer *w, int revents)	1380	t2_cb (EV_P_ ev_timer *w, int revents)
1219	{	1381	{
1220	struct my_biggy big = (struct my_biggy *)	1382	struct my_biggy big = (struct my_biggy *)
1221	(((char *)w) - offsetof (struct my_biggy, t2));	1383	(((char *)w) - offsetof (struct my_biggy, t2));
1222	}	1384	}
		1385
		1386	=head2 WATCHER STATES
		1387
		1388	There are various watcher states mentioned throughout this manual -
		1389	active, pending and so on. In this section these states and the rules to
		1390	transition between them will be described in more detail - and while these
		1391	rules might look complicated, they usually do "the right thing".
		1392
		1393	=over 4
		1394
		1395	=item initialiased
		1396
		1397	Before a watcher can be registered with the event looop it has to be
		1398	initialised. This can be done with a call to C<ev_TYPE_init>, or calls to
		1399	C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function.
		1400
		1401	In this state it is simply some block of memory that is suitable for use
		1402	in an event loop. It can be moved around, freed, reused etc. at will.
		1403
		1404	=item started/running/active
		1405
		1406	Once a watcher has been started with a call to C<ev_TYPE_start> it becomes
		1407	property of the event loop, and is actively waiting for events. While in
		1408	this state it cannot be accessed (except in a few documented ways), moved,
		1409	freed or anything else - the only legal thing is to keep a pointer to it,
		1410	and call libev functions on it that are documented to work on active watchers.
		1411
		1412	=item pending
		1413
		1414	If a watcher is active and libev determines that an event it is interested
		1415	in has occurred (such as a timer expiring), it will become pending. It will
		1416	stay in this pending state until either it is stopped or its callback is
		1417	about to be invoked, so it is not normally pending inside the watcher
		1418	callback.
		1419
		1420	The watcher might or might not be active while it is pending (for example,
		1421	an expired non-repeating timer can be pending but no longer active). If it
		1422	is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>),
		1423	but it is still property of the event loop at this time, so cannot be
		1424	moved, freed or reused. And if it is active the rules described in the
		1425	previous item still apply.
		1426
		1427	It is also possible to feed an event on a watcher that is not active (e.g.
		1428	via C<ev_feed_event>), in which case it becomes pending without being
		1429	active.
		1430
		1431	=item stopped
		1432
		1433	A watcher can be stopped implicitly by libev (in which case it might still
		1434	be pending), or explicitly by calling its C<ev_TYPE_stop> function. The
		1435	latter will clear any pending state the watcher might be in, regardless
		1436	of whether it was active or not, so stopping a watcher explicitly before
		1437	freeing it is often a good idea.
		1438
		1439	While stopped (and not pending) the watcher is essentially in the
		1440	initialised state, that is it can be reused, moved, modified in any way
		1441	you wish.
		1442
		1443	=back
1223		1444
1224	=head2 WATCHER PRIORITY MODELS	1445	=head2 WATCHER PRIORITY MODELS
1225		1446
1226	Many event loops support I<watcher priorities>, which are usually small	1447	Many event loops support I<watcher priorities>, which are usually small
1227	integers that influence the ordering of event callback invocation	1448	integers that influence the ordering of event callback invocation
…		…
1270		1491
1271	For example, to emulate how many other event libraries handle priorities,	1492	For example, to emulate how many other event libraries handle priorities,
1272	you can associate an C<ev_idle> watcher to each such watcher, and in	1493	you can associate an C<ev_idle> watcher to each such watcher, and in
1273	the normal watcher callback, you just start the idle watcher. The real	1494	the normal watcher callback, you just start the idle watcher. The real
1274	processing is done in the idle watcher callback. This causes libev to	1495	processing is done in the idle watcher callback. This causes libev to
1275	continously poll and process kernel event data for the watcher, but when	1496	continuously poll and process kernel event data for the watcher, but when
1276	the lock-out case is known to be rare (which in turn is rare :), this is	1497	the lock-out case is known to be rare (which in turn is rare :), this is
1277	workable.	1498	workable.
1278		1499
1279	Usually, however, the lock-out model implemented that way will perform	1500	Usually, however, the lock-out model implemented that way will perform
1280	miserably under the type of load it was designed to handle. In that case,	1501	miserably under the type of load it was designed to handle. In that case,
…		…
1294	{	1515	{
1295	// stop the I/O watcher, we received the event, but	1516	// stop the I/O watcher, we received the event, but
1296	// are not yet ready to handle it.	1517	// are not yet ready to handle it.
1297	ev_io_stop (EV_A_ w);	1518	ev_io_stop (EV_A_ w);
1298		1519
1299	// start the idle watcher to ahndle the actual event.	1520	// start the idle watcher to handle the actual event.
1300	// it will not be executed as long as other watchers	1521	// it will not be executed as long as other watchers
1301	// with the default priority are receiving events.	1522	// with the default priority are receiving events.
1302	ev_idle_start (EV_A_ &idle);	1523	ev_idle_start (EV_A_ &idle);
1303	}	1524	}
1304		1525
…		…
1358		1579
1359	If you cannot use non-blocking mode, then force the use of a	1580	If you cannot use non-blocking mode, then force the use of a
1360	known-to-be-good backend (at the time of this writing, this includes only	1581	known-to-be-good backend (at the time of this writing, this includes only
1361	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file	1582	C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file
1362	descriptors for which non-blocking operation makes no sense (such as	1583	descriptors for which non-blocking operation makes no sense (such as
1363	files) - libev doesn't guarentee any specific behaviour in that case.	1584	files) - libev doesn't guarantee any specific behaviour in that case.
1364		1585
1365	Another thing you have to watch out for is that it is quite easy to	1586	Another thing you have to watch out for is that it is quite easy to
1366	receive "spurious" readiness notifications, that is your callback might	1587	receive "spurious" readiness notifications, that is your callback might
1367	be called with C<EV_READ> but a subsequent C<read>(2) will actually block	1588	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
1368	because there is no data. Not only are some backends known to create a	1589	because there is no data. Not only are some backends known to create a
…		…
1433		1654
1434	So when you encounter spurious, unexplained daemon exits, make sure you	1655	So when you encounter spurious, unexplained daemon exits, make sure you
1435	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon	1656	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon
1436	somewhere, as that would have given you a big clue).	1657	somewhere, as that would have given you a big clue).
1437		1658
		1659	=head3 The special problem of accept()ing when you can't
		1660
		1661	Many implementations of the POSIX C<accept> function (for example,
		1662	found in post-2004 Linux) have the peculiar behaviour of not removing a
		1663	connection from the pending queue in all error cases.
		1664
		1665	For example, larger servers often run out of file descriptors (because
		1666	of resource limits), causing C<accept> to fail with C<ENFILE> but not
		1667	rejecting the connection, leading to libev signalling readiness on
		1668	the next iteration again (the connection still exists after all), and
		1669	typically causing the program to loop at 100% CPU usage.
		1670
		1671	Unfortunately, the set of errors that cause this issue differs between
		1672	operating systems, there is usually little the app can do to remedy the
		1673	situation, and no known thread-safe method of removing the connection to
		1674	cope with overload is known (to me).
		1675
		1676	One of the easiest ways to handle this situation is to just ignore it
		1677	- when the program encounters an overload, it will just loop until the
		1678	situation is over. While this is a form of busy waiting, no OS offers an
		1679	event-based way to handle this situation, so it's the best one can do.
		1680
		1681	A better way to handle the situation is to log any errors other than
		1682	C<EAGAIN> and C<EWOULDBLOCK>, making sure not to flood the log with such
		1683	messages, and continue as usual, which at least gives the user an idea of
		1684	what could be wrong ("raise the ulimit!"). For extra points one could stop
		1685	the C<ev_io> watcher on the listening fd "for a while", which reduces CPU
		1686	usage.
		1687
		1688	If your program is single-threaded, then you could also keep a dummy file
		1689	descriptor for overload situations (e.g. by opening F</dev/null>), and
		1690	when you run into C<ENFILE> or C<EMFILE>, close it, run C<accept>,
		1691	close that fd, and create a new dummy fd. This will gracefully refuse
		1692	clients under typical overload conditions.
		1693
		1694	The last way to handle it is to simply log the error and C<exit>, as
		1695	is often done with C<malloc> failures, but this results in an easy
		1696	opportunity for a DoS attack.
1438		1697
1439	=head3 Watcher-Specific Functions	1698	=head3 Watcher-Specific Functions
1440		1699
1441	=over 4	1700	=over 4
1442		1701
…		…
1474	...	1733	...
1475	struct ev_loop *loop = ev_default_init (0);	1734	struct ev_loop *loop = ev_default_init (0);
1476	ev_io stdin_readable;	1735	ev_io stdin_readable;
1477	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1736	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1478	ev_io_start (loop, &stdin_readable);	1737	ev_io_start (loop, &stdin_readable);
1479	ev_loop (loop, 0);	1738	ev_run (loop, 0);
1480		1739
1481		1740
1482	=head2 C<ev_timer> - relative and optionally repeating timeouts	1741	=head2 C<ev_timer> - relative and optionally repeating timeouts
1483		1742
1484	Timer watchers are simple relative timers that generate an event after a	1743	Timer watchers are simple relative timers that generate an event after a
…		…
1493	The callback is guaranteed to be invoked only I<after> its timeout has	1752	The callback is guaranteed to be invoked only I<after> its timeout has
1494	passed (not I<at>, so on systems with very low-resolution clocks this	1753	passed (not I<at>, so on systems with very low-resolution clocks this
1495	might introduce a small delay). If multiple timers become ready during the	1754	might introduce a small delay). If multiple timers become ready during the
1496	same loop iteration then the ones with earlier time-out values are invoked	1755	same loop iteration then the ones with earlier time-out values are invoked
1497	before ones of the same priority with later time-out values (but this is	1756	before ones of the same priority with later time-out values (but this is
1498	no longer true when a callback calls C<ev_loop> recursively).	1757	no longer true when a callback calls C<ev_run> recursively).
1499		1758
1500	=head3 Be smart about timeouts	1759	=head3 Be smart about timeouts
1501		1760
1502	Many real-world problems involve some kind of timeout, usually for error	1761	Many real-world problems involve some kind of timeout, usually for error
1503	recovery. A typical example is an HTTP request - if the other side hangs,	1762	recovery. A typical example is an HTTP request - if the other side hangs,
…		…
1589	ev_tstamp timeout = last_activity + 60.;	1848	ev_tstamp timeout = last_activity + 60.;
1590		1849
1591	// if last_activity + 60. is older than now, we did time out	1850	// if last_activity + 60. is older than now, we did time out
1592	if (timeout < now)	1851	if (timeout < now)
1593	{	1852	{
1594	// timeout occured, take action	1853	// timeout occurred, take action
1595	}	1854	}
1596	else	1855	else
1597	{	1856	{
1598	// callback was invoked, but there was some activity, re-arm	1857	// callback was invoked, but there was some activity, re-arm
1599	// the watcher to fire in last_activity + 60, which is	1858	// the watcher to fire in last_activity + 60, which is
…		…
1621	to the current time (meaning we just have some activity :), then call the	1880	to the current time (meaning we just have some activity :), then call the
1622	callback, which will "do the right thing" and start the timer:	1881	callback, which will "do the right thing" and start the timer:
1623		1882
1624	ev_init (timer, callback);	1883	ev_init (timer, callback);
1625	last_activity = ev_now (loop);	1884	last_activity = ev_now (loop);
1626	callback (loop, timer, EV_TIMEOUT);	1885	callback (loop, timer, EV_TIMER);
1627		1886
1628	And when there is some activity, simply store the current time in	1887	And when there is some activity, simply store the current time in
1629	C<last_activity>, no libev calls at all:	1888	C<last_activity>, no libev calls at all:
1630		1889
1631	last_actiivty = ev_now (loop);	1890	last_activity = ev_now (loop);
1632		1891
1633	This technique is slightly more complex, but in most cases where the	1892	This technique is slightly more complex, but in most cases where the
1634	time-out is unlikely to be triggered, much more efficient.	1893	time-out is unlikely to be triggered, much more efficient.
1635		1894
1636	Changing the timeout is trivial as well (if it isn't hard-coded in the	1895	Changing the timeout is trivial as well (if it isn't hard-coded in the
…		…
1674		1933
1675	=head3 The special problem of time updates	1934	=head3 The special problem of time updates
1676		1935
1677	Establishing the current time is a costly operation (it usually takes at	1936	Establishing the current time is a costly operation (it usually takes at
1678	least two system calls): EV therefore updates its idea of the current	1937	least two system calls): EV therefore updates its idea of the current
1679	time only before and after C<ev_loop> collects new events, which causes a	1938	time only before and after C<ev_run> collects new events, which causes a
1680	growing difference between C<ev_now ()> and C<ev_time ()> when handling	1939	growing difference between C<ev_now ()> and C<ev_time ()> when handling
1681	lots of events in one iteration.	1940	lots of events in one iteration.
1682		1941
1683	The relative timeouts are calculated relative to the C<ev_now ()>	1942	The relative timeouts are calculated relative to the C<ev_now ()>
1684	time. This is usually the right thing as this timestamp refers to the time	1943	time. This is usually the right thing as this timestamp refers to the time
…		…
1690		1949
1691	If the event loop is suspended for a long time, you can also force an	1950	If the event loop is suspended for a long time, you can also force an
1692	update of the time returned by C<ev_now ()> by calling C<ev_now_update	1951	update of the time returned by C<ev_now ()> by calling C<ev_now_update
1693	()>.	1952	()>.
1694		1953
		1954	=head3 The special problems of suspended animation
		1955
		1956	When you leave the server world it is quite customary to hit machines that
		1957	can suspend/hibernate - what happens to the clocks during such a suspend?
		1958
		1959	Some quick tests made with a Linux 2.6.28 indicate that a suspend freezes
		1960	all processes, while the clocks (C<times>, C<CLOCK_MONOTONIC>) continue
		1961	to run until the system is suspended, but they will not advance while the
		1962	system is suspended. That means, on resume, it will be as if the program
		1963	was frozen for a few seconds, but the suspend time will not be counted
		1964	towards C<ev_timer> when a monotonic clock source is used. The real time
		1965	clock advanced as expected, but if it is used as sole clocksource, then a
		1966	long suspend would be detected as a time jump by libev, and timers would
		1967	be adjusted accordingly.
		1968
		1969	I would not be surprised to see different behaviour in different between
		1970	operating systems, OS versions or even different hardware.
		1971
		1972	The other form of suspend (job control, or sending a SIGSTOP) will see a
		1973	time jump in the monotonic clocks and the realtime clock. If the program
		1974	is suspended for a very long time, and monotonic clock sources are in use,
		1975	then you can expect C<ev_timer>s to expire as the full suspension time
		1976	will be counted towards the timers. When no monotonic clock source is in
		1977	use, then libev will again assume a timejump and adjust accordingly.
		1978
		1979	It might be beneficial for this latter case to call C<ev_suspend>
		1980	and C<ev_resume> in code that handles C<SIGTSTP>, to at least get
		1981	deterministic behaviour in this case (you can do nothing against
		1982	C<SIGSTOP>).
		1983
1695	=head3 Watcher-Specific Functions and Data Members	1984	=head3 Watcher-Specific Functions and Data Members
1696		1985
1697	=over 4	1986	=over 4
1698		1987
1699	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	1988	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
…		…
1725	C<repeat> value), or reset the running timer to the C<repeat> value.	2014	C<repeat> value), or reset the running timer to the C<repeat> value.
1726		2015
1727	This sounds a bit complicated, see L<Be smart about timeouts>, above, for a	2016	This sounds a bit complicated, see L<Be smart about timeouts>, above, for a
1728	usage example.	2017	usage example.
1729		2018
		2019	=item ev_tstamp ev_timer_remaining (loop, ev_timer *)
		2020
		2021	Returns the remaining time until a timer fires. If the timer is active,
		2022	then this time is relative to the current event loop time, otherwise it's
		2023	the timeout value currently configured.
		2024
		2025	That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns
		2026	C<5>. When the timer is started and one second passes, C<ev_timer_remaining>
		2027	will return C<4>. When the timer expires and is restarted, it will return
		2028	roughly C<7> (likely slightly less as callback invocation takes some time,
		2029	too), and so on.
		2030
1730	=item ev_tstamp repeat [read-write]	2031	=item ev_tstamp repeat [read-write]
1731		2032
1732	The current C<repeat> value. Will be used each time the watcher times out	2033	The current C<repeat> value. Will be used each time the watcher times out
1733	or C<ev_timer_again> is called, and determines the next timeout (if any),	2034	or C<ev_timer_again> is called, and determines the next timeout (if any),
1734	which is also when any modifications are taken into account.	2035	which is also when any modifications are taken into account.
…		…
1759	}	2060	}
1760		2061
1761	ev_timer mytimer;	2062	ev_timer mytimer;
1762	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	2063	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1763	ev_timer_again (&mytimer); /* start timer */	2064	ev_timer_again (&mytimer); /* start timer */
1764	ev_loop (loop, 0);	2065	ev_run (loop, 0);
1765		2066
1766	// and in some piece of code that gets executed on any "activity":	2067	// and in some piece of code that gets executed on any "activity":
1767	// reset the timeout to start ticking again at 10 seconds	2068	// reset the timeout to start ticking again at 10 seconds
1768	ev_timer_again (&mytimer);	2069	ev_timer_again (&mytimer);
1769		2070
…		…
1795		2096
1796	As with timers, the callback is guaranteed to be invoked only when the	2097	As with timers, the callback is guaranteed to be invoked only when the
1797	point in time where it is supposed to trigger has passed. If multiple	2098	point in time where it is supposed to trigger has passed. If multiple
1798	timers become ready during the same loop iteration then the ones with	2099	timers become ready during the same loop iteration then the ones with
1799	earlier time-out values are invoked before ones with later time-out values	2100	earlier time-out values are invoked before ones with later time-out values
1800	(but this is no longer true when a callback calls C<ev_loop> recursively).	2101	(but this is no longer true when a callback calls C<ev_run> recursively).
1801		2102
1802	=head3 Watcher-Specific Functions and Data Members	2103	=head3 Watcher-Specific Functions and Data Members
1803		2104
1804	=over 4	2105	=over 4
1805		2106
…		…
1933	Example: Call a callback every hour, or, more precisely, whenever the	2234	Example: Call a callback every hour, or, more precisely, whenever the
1934	system time is divisible by 3600. The callback invocation times have	2235	system time is divisible by 3600. The callback invocation times have
1935	potentially a lot of jitter, but good long-term stability.	2236	potentially a lot of jitter, but good long-term stability.
1936		2237
1937	static void	2238	static void
1938	clock_cb (struct ev_loop *loop, ev_io *w, int revents)	2239	clock_cb (struct ev_loop *loop, ev_periodic *w, int revents)
1939	{	2240	{
1940	... its now a full hour (UTC, or TAI or whatever your clock follows)	2241	... its now a full hour (UTC, or TAI or whatever your clock follows)
1941	}	2242	}
1942		2243
1943	ev_periodic hourly_tick;	2244	ev_periodic hourly_tick;
…		…
1966		2267
1967	=head2 C<ev_signal> - signal me when a signal gets signalled!	2268	=head2 C<ev_signal> - signal me when a signal gets signalled!
1968		2269
1969	Signal watchers will trigger an event when the process receives a specific	2270	Signal watchers will trigger an event when the process receives a specific
1970	signal one or more times. Even though signals are very asynchronous, libev	2271	signal one or more times. Even though signals are very asynchronous, libev
1971	will try it's best to deliver signals synchronously, i.e. as part of the	2272	will try its best to deliver signals synchronously, i.e. as part of the
1972	normal event processing, like any other event.	2273	normal event processing, like any other event.
1973		2274
1974	If you want signals asynchronously, just use C<sigaction> as you would	2275	If you want signals to be delivered truly asynchronously, just use
1975	do without libev and forget about sharing the signal. You can even use	2276	C<sigaction> as you would do without libev and forget about sharing
1976	C<ev_async> from a signal handler to synchronously wake up an event loop.	2277	the signal. You can even use C<ev_async> from a signal handler to
		2278	synchronously wake up an event loop.
1977		2279
1978	You can configure as many watchers as you like per signal. Only when the	2280	You can configure as many watchers as you like for the same signal, but
		2281	only within the same loop, i.e. you can watch for C<SIGINT> in your
		2282	default loop and for C<SIGIO> in another loop, but you cannot watch for
		2283	C<SIGINT> in both the default loop and another loop at the same time. At
		2284	the moment, C<SIGCHLD> is permanently tied to the default loop.
		2285
1979	first watcher gets started will libev actually register a signal handler	2286	When the first watcher gets started will libev actually register something
1980	with the kernel (thus it coexists with your own signal handlers as long as	2287	with the kernel (thus it coexists with your own signal handlers as long as
1981	you don't register any with libev for the same signal). Similarly, when	2288	you don't register any with libev for the same signal).
1982	the last signal watcher for a signal is stopped, libev will reset the
1983	signal handler to SIG_DFL (regardless of what it was set to before).
1984		2289
1985	If possible and supported, libev will install its handlers with	2290	If possible and supported, libev will install its handlers with
1986	C<SA_RESTART> behaviour enabled, so system calls should not be unduly	2291	C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should
1987	interrupted. If you have a problem with system calls getting interrupted by	2292	not be unduly interrupted. If you have a problem with system calls getting
1988	signals you can block all signals in an C<ev_check> watcher and unblock	2293	interrupted by signals you can block all signals in an C<ev_check> watcher
1989	them in an C<ev_prepare> watcher.	2294	and unblock them in an C<ev_prepare> watcher.
		2295
		2296	=head3 The special problem of inheritance over fork/execve/pthread_create
		2297
		2298	Both the signal mask (C<sigprocmask>) and the signal disposition
		2299	(C<sigaction>) are unspecified after starting a signal watcher (and after
		2300	stopping it again), that is, libev might or might not block the signal,
		2301	and might or might not set or restore the installed signal handler.
		2302
		2303	While this does not matter for the signal disposition (libev never
		2304	sets signals to C<SIG_IGN>, so handlers will be reset to C<SIG_DFL> on
		2305	C<execve>), this matters for the signal mask: many programs do not expect
		2306	certain signals to be blocked.
		2307
		2308	This means that before calling C<exec> (from the child) you should reset
		2309	the signal mask to whatever "default" you expect (all clear is a good
		2310	choice usually).
		2311
		2312	The simplest way to ensure that the signal mask is reset in the child is
		2313	to install a fork handler with C<pthread_atfork> that resets it. That will
		2314	catch fork calls done by libraries (such as the libc) as well.
		2315
		2316	In current versions of libev, the signal will not be blocked indefinitely
		2317	unless you use the C<signalfd> API (C<EV_SIGNALFD>). While this reduces
		2318	the window of opportunity for problems, it will not go away, as libev
		2319	I<has> to modify the signal mask, at least temporarily.
		2320
		2321	So I can't stress this enough: I<If you do not reset your signal mask when
		2322	you expect it to be empty, you have a race condition in your code>. This
		2323	is not a libev-specific thing, this is true for most event libraries.
1990		2324
1991	=head3 Watcher-Specific Functions and Data Members	2325	=head3 Watcher-Specific Functions and Data Members
1992		2326
1993	=over 4	2327	=over 4
1994		2328
…		…
2010	Example: Try to exit cleanly on SIGINT.	2344	Example: Try to exit cleanly on SIGINT.
2011		2345
2012	static void	2346	static void
2013	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)	2347	sigint_cb (struct ev_loop *loop, ev_signal *w, int revents)
2014	{	2348	{
2015	ev_unloop (loop, EVUNLOOP_ALL);	2349	ev_break (loop, EVBREAK_ALL);
2016	}	2350	}
2017		2351
2018	ev_signal signal_watcher;	2352	ev_signal signal_watcher;
2019	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	2353	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
2020	ev_signal_start (loop, &signal_watcher);	2354	ev_signal_start (loop, &signal_watcher);
…		…
2039	libev)	2373	libev)
2040		2374
2041	=head3 Process Interaction	2375	=head3 Process Interaction
2042		2376
2043	Libev grabs C<SIGCHLD> as soon as the default event loop is	2377	Libev grabs C<SIGCHLD> as soon as the default event loop is
2044	initialised. This is necessary to guarantee proper behaviour even if	2378	initialised. This is necessary to guarantee proper behaviour even if the
2045	the first child watcher is started after the child exits. The occurrence	2379	first child watcher is started after the child exits. The occurrence
2046	of C<SIGCHLD> is recorded asynchronously, but child reaping is done	2380	of C<SIGCHLD> is recorded asynchronously, but child reaping is done
2047	synchronously as part of the event loop processing. Libev always reaps all	2381	synchronously as part of the event loop processing. Libev always reaps all
2048	children, even ones not watched.	2382	children, even ones not watched.
2049		2383
2050	=head3 Overriding the Built-In Processing	2384	=head3 Overriding the Built-In Processing
…		…
2060	=head3 Stopping the Child Watcher	2394	=head3 Stopping the Child Watcher
2061		2395
2062	Currently, the child watcher never gets stopped, even when the	2396	Currently, the child watcher never gets stopped, even when the
2063	child terminates, so normally one needs to stop the watcher in the	2397	child terminates, so normally one needs to stop the watcher in the
2064	callback. Future versions of libev might stop the watcher automatically	2398	callback. Future versions of libev might stop the watcher automatically
2065	when a child exit is detected.	2399	when a child exit is detected (calling C<ev_child_stop> twice is not a
		2400	problem).
2066		2401
2067	=head3 Watcher-Specific Functions and Data Members	2402	=head3 Watcher-Specific Functions and Data Members
2068		2403
2069	=over 4	2404	=over 4
2070		2405
…		…
2405		2740
2406	Prepare and check watchers are usually (but not always) used in pairs:	2741	Prepare and check watchers are usually (but not always) used in pairs:
2407	prepare watchers get invoked before the process blocks and check watchers	2742	prepare watchers get invoked before the process blocks and check watchers
2408	afterwards.	2743	afterwards.
2409		2744
2410	You I<must not> call C<ev_loop> or similar functions that enter	2745	You I<must not> call C<ev_run> or similar functions that enter
2411	the current event loop from either C<ev_prepare> or C<ev_check>	2746	the current event loop from either C<ev_prepare> or C<ev_check>
2412	watchers. Other loops than the current one are fine, however. The	2747	watchers. Other loops than the current one are fine, however. The
2413	rationale behind this is that you do not need to check for recursion in	2748	rationale behind this is that you do not need to check for recursion in
2414	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,	2749	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,
2415	C<ev_check> so if you have one watcher of each kind they will always be	2750	C<ev_check> so if you have one watcher of each kind they will always be
…		…
2583		2918
2584	if (timeout >= 0)	2919	if (timeout >= 0)
2585	// create/start timer	2920	// create/start timer
2586		2921
2587	// poll	2922	// poll
2588	ev_loop (EV_A_ 0);	2923	ev_run (EV_A_ 0);
2589		2924
2590	// stop timer again	2925	// stop timer again
2591	if (timeout >= 0)	2926	if (timeout >= 0)
2592	ev_timer_stop (EV_A_ &to);	2927	ev_timer_stop (EV_A_ &to);
2593		2928
…		…
2671	if you do not want that, you need to temporarily stop the embed watcher).	3006	if you do not want that, you need to temporarily stop the embed watcher).
2672		3007
2673	=item ev_embed_sweep (loop, ev_embed *)	3008	=item ev_embed_sweep (loop, ev_embed *)
2674		3009
2675	Make a single, non-blocking sweep over the embedded loop. This works	3010	Make a single, non-blocking sweep over the embedded loop. This works
2676	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	3011	similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most
2677	appropriate way for embedded loops.	3012	appropriate way for embedded loops.
2678		3013
2679	=item struct ev_loop *other [read-only]	3014	=item struct ev_loop *other [read-only]
2680		3015
2681	The embedded event loop.	3016	The embedded event loop.
…		…
2741	C<ev_default_fork> cheats and calls it in the wrong process, the fork	3076	C<ev_default_fork> cheats and calls it in the wrong process, the fork
2742	handlers will be invoked, too, of course.	3077	handlers will be invoked, too, of course.
2743		3078
2744	=head3 The special problem of life after fork - how is it possible?	3079	=head3 The special problem of life after fork - how is it possible?
2745		3080
2746	Most uses of C<fork()> consist of forking, then some simple calls to ste	3081	Most uses of C<fork()> consist of forking, then some simple calls to set
2747	up/change the process environment, followed by a call to C<exec()>. This	3082	up/change the process environment, followed by a call to C<exec()>. This
2748	sequence should be handled by libev without any problems.	3083	sequence should be handled by libev without any problems.
2749		3084
2750	This changes when the application actually wants to do event handling	3085	This changes when the application actually wants to do event handling
2751	in the child, or both parent in child, in effect "continuing" after the	3086	in the child, or both parent in child, in effect "continuing" after the
…		…
2767	disadvantage of having to use multiple event loops (which do not support	3102	disadvantage of having to use multiple event loops (which do not support
2768	signal watchers).	3103	signal watchers).
2769		3104
2770	When this is not possible, or you want to use the default loop for	3105	When this is not possible, or you want to use the default loop for
2771	other reasons, then in the process that wants to start "fresh", call	3106	other reasons, then in the process that wants to start "fresh", call
2772	C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying	3107	C<ev_loop_destroy (EV_DEFAULT)> followed by C<ev_default_loop (...)>.
2773	the default loop will "orphan" (not stop) all registered watchers, so you	3108	Destroying the default loop will "orphan" (not stop) all registered
2774	have to be careful not to execute code that modifies those watchers. Note	3109	watchers, so you have to be careful not to execute code that modifies
2775	also that in that case, you have to re-register any signal watchers.	3110	those watchers. Note also that in that case, you have to re-register any
		3111	signal watchers.
2776		3112
2777	=head3 Watcher-Specific Functions and Data Members	3113	=head3 Watcher-Specific Functions and Data Members
2778		3114
2779	=over 4	3115	=over 4
2780		3116
2781	=item ev_fork_init (ev_signal *, callback)	3117	=item ev_fork_init (ev_fork *, callback)
2782		3118
2783	Initialises and configures the fork watcher - it has no parameters of any	3119	Initialises and configures the fork watcher - it has no parameters of any
2784	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,	3120	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
2785	believe me.	3121	really.
2786		3122
2787	=back	3123	=back
2788		3124
2789		3125
		3126	=head2 C<ev_cleanup> - even the best things end
		3127
		3128	Cleanup watchers are called just before the event loop is being destroyed
		3129	by a call to C<ev_loop_destroy>.
		3130
		3131	While there is no guarantee that the event loop gets destroyed, cleanup
		3132	watchers provide a convenient method to install cleanup hooks for your
		3133	program, worker threads and so on - you just to make sure to destroy the
		3134	loop when you want them to be invoked.
		3135
		3136	Cleanup watchers are invoked in the same way as any other watcher. Unlike
		3137	all other watchers, they do not keep a reference to the event loop (which
		3138	makes a lot of sense if you think about it). Like all other watchers, you
		3139	can call libev functions in the callback, except C<ev_cleanup_start>.
		3140
		3141	=head3 Watcher-Specific Functions and Data Members
		3142
		3143	=over 4
		3144
		3145	=item ev_cleanup_init (ev_cleanup *, callback)
		3146
		3147	Initialises and configures the cleanup watcher - it has no parameters of
		3148	any kind. There is a C<ev_cleanup_set> macro, but using it is utterly
		3149	pointless, I assure you.
		3150
		3151	=back
		3152
		3153	Example: Register an atexit handler to destroy the default loop, so any
		3154	cleanup functions are called.
		3155
		3156	static void
		3157	program_exits (void)
		3158	{
		3159	ev_loop_destroy (EV_DEFAULT_UC);
		3160	}
		3161
		3162	...
		3163	atexit (program_exits);
		3164
		3165
2790	=head2 C<ev_async> - how to wake up another event loop	3166	=head2 C<ev_async> - how to wake up an event loop
2791		3167
2792	In general, you cannot use an C<ev_loop> from multiple threads or other	3168	In general, you cannot use an C<ev_run> from multiple threads or other
2793	asynchronous sources such as signal handlers (as opposed to multiple event	3169	asynchronous sources such as signal handlers (as opposed to multiple event
2794	loops - those are of course safe to use in different threads).	3170	loops - those are of course safe to use in different threads).
2795		3171
2796	Sometimes, however, you need to wake up another event loop you do not	3172	Sometimes, however, you need to wake up an event loop you do not control,
2797	control, for example because it belongs to another thread. This is what	3173	for example because it belongs to another thread. This is what C<ev_async>
2798	C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you	3174	watchers do: as long as the C<ev_async> watcher is active, you can signal
2799	can signal it by calling C<ev_async_send>, which is thread- and signal	3175	it by calling C<ev_async_send>, which is thread- and signal safe.
2800	safe.
2801		3176
2802	This functionality is very similar to C<ev_signal> watchers, as signals,	3177	This functionality is very similar to C<ev_signal> watchers, as signals,
2803	too, are asynchronous in nature, and signals, too, will be compressed	3178	too, are asynchronous in nature, and signals, too, will be compressed
2804	(i.e. the number of callback invocations may be less than the number of	3179	(i.e. the number of callback invocations may be less than the number of
2805	C<ev_async_sent> calls).	3180	C<ev_async_sent> calls).
…		…
2810	=head3 Queueing	3185	=head3 Queueing
2811		3186
2812	C<ev_async> does not support queueing of data in any way. The reason	3187	C<ev_async> does not support queueing of data in any way. The reason
2813	is that the author does not know of a simple (or any) algorithm for a	3188	is that the author does not know of a simple (or any) algorithm for a
2814	multiple-writer-single-reader queue that works in all cases and doesn't	3189	multiple-writer-single-reader queue that works in all cases and doesn't
2815	need elaborate support such as pthreads.	3190	need elaborate support such as pthreads or unportable memory access
		3191	semantics.
2816		3192
2817	That means that if you want to queue data, you have to provide your own	3193	That means that if you want to queue data, you have to provide your own
2818	queue. But at least I can tell you how to implement locking around your	3194	queue. But at least I can tell you how to implement locking around your
2819	queue:	3195	queue:
2820		3196
…		…
2959		3335
2960	If C<timeout> is less than 0, then no timeout watcher will be	3336	If C<timeout> is less than 0, then no timeout watcher will be
2961	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and	3337	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and
2962	repeat = 0) will be started. C<0> is a valid timeout.	3338	repeat = 0) will be started. C<0> is a valid timeout.
2963		3339
2964	The callback has the type C<void (*cb)(int revents, void *arg)> and gets	3340	The callback has the type C<void (*cb)(int revents, void *arg)> and is
2965	passed an C<revents> set like normal event callbacks (a combination of	3341	passed an C<revents> set like normal event callbacks (a combination of
2966	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>	3342	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMER>) and the C<arg>
2967	value passed to C<ev_once>. Note that it is possible to receive I<both>	3343	value passed to C<ev_once>. Note that it is possible to receive I<both>
2968	a timeout and an io event at the same time - you probably should give io	3344	a timeout and an io event at the same time - you probably should give io
2969	events precedence.	3345	events precedence.
2970		3346
2971	Example: wait up to ten seconds for data to appear on STDIN_FILENO.	3347	Example: wait up to ten seconds for data to appear on STDIN_FILENO.
2972		3348
2973	static void stdin_ready (int revents, void *arg)	3349	static void stdin_ready (int revents, void *arg)
2974	{	3350	{
2975	if (revents & EV_READ)	3351	if (revents & EV_READ)
2976	/* stdin might have data for us, joy! */;	3352	/* stdin might have data for us, joy! */;
2977	else if (revents & EV_TIMEOUT)	3353	else if (revents & EV_TIMER)
2978	/* doh, nothing entered */;	3354	/* doh, nothing entered */;
2979	}	3355	}
2980		3356
2981	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	3357	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
2982		3358
2983	=item ev_feed_event (struct ev_loop *, watcher *, int revents)
2984
2985	Feeds the given event set into the event loop, as if the specified event
2986	had happened for the specified watcher (which must be a pointer to an
2987	initialised but not necessarily started event watcher).
2988
2989	=item ev_feed_fd_event (struct ev_loop *, int fd, int revents)	3359	=item ev_feed_fd_event (loop, int fd, int revents)
2990		3360
2991	Feed an event on the given fd, as if a file descriptor backend detected	3361	Feed an event on the given fd, as if a file descriptor backend detected
2992	the given events it.	3362	the given events it.
2993		3363
2994	=item ev_feed_signal_event (struct ev_loop *loop, int signum)	3364	=item ev_feed_signal_event (loop, int signum)
2995		3365
2996	Feed an event as if the given signal occurred (C<loop> must be the default	3366	Feed an event as if the given signal occurred (C<loop> must be the default
2997	loop!).	3367	loop!).
2998		3368
2999	=back	3369	=back
…		…
3018	=item * Priorities are not currently supported. Initialising priorities	3388	=item * Priorities are not currently supported. Initialising priorities
3019	will fail and all watchers will have the same priority, even though there	3389	will fail and all watchers will have the same priority, even though there
3020	is an ev_pri field.	3390	is an ev_pri field.
3021		3391
3022	=item * In libevent, the last base created gets the signals, in libev, the	3392	=item * In libevent, the last base created gets the signals, in libev, the
3023	first base created (== the default loop) gets the signals.	3393	base that registered the signal gets the signals.
3024		3394
3025	=item * Other members are not supported.	3395	=item * Other members are not supported.
3026		3396
3027	=item * The libev emulation is I<not> ABI compatible to libevent, you need	3397	=item * The libev emulation is I<not> ABI compatible to libevent, you need
3028	to use the libev header file and library.	3398	to use the libev header file and library.
…		…
3079		3449
3080	=over 4	3450	=over 4
3081		3451
3082	=item ev::TYPE::TYPE ()	3452	=item ev::TYPE::TYPE ()
3083		3453
3084	=item ev::TYPE::TYPE (struct ev_loop *)	3454	=item ev::TYPE::TYPE (loop)
3085		3455
3086	=item ev::TYPE::~TYPE	3456	=item ev::TYPE::~TYPE
3087		3457
3088	The constructor (optionally) takes an event loop to associate the watcher	3458	The constructor (optionally) takes an event loop to associate the watcher
3089	with. If it is omitted, it will use C<EV_DEFAULT>.	3459	with. If it is omitted, it will use C<EV_DEFAULT>.
…		…
3122	myclass obj;	3492	myclass obj;
3123	ev::io iow;	3493	ev::io iow;
3124	iow.set <myclass, &myclass::io_cb> (&obj);	3494	iow.set <myclass, &myclass::io_cb> (&obj);
3125		3495
3126	=item w->set (object *)	3496	=item w->set (object *)
3127
3128	This is an B<experimental> feature that might go away in a future version.
3129		3497
3130	This is a variation of a method callback - leaving out the method to call	3498	This is a variation of a method callback - leaving out the method to call
3131	will default the method to C<operator ()>, which makes it possible to use	3499	will default the method to C<operator ()>, which makes it possible to use
3132	functor objects without having to manually specify the C<operator ()> all	3500	functor objects without having to manually specify the C<operator ()> all
3133	the time. Incidentally, you can then also leave out the template argument	3501	the time. Incidentally, you can then also leave out the template argument
…		…
3166	Example: Use a plain function as callback.	3534	Example: Use a plain function as callback.
3167		3535
3168	static void io_cb (ev::io &w, int revents) { }	3536	static void io_cb (ev::io &w, int revents) { }
3169	iow.set <io_cb> ();	3537	iow.set <io_cb> ();
3170		3538
3171	=item w->set (struct ev_loop *)	3539	=item w->set (loop)
3172		3540
3173	Associates a different C<struct ev_loop> with this watcher. You can only	3541	Associates a different C<struct ev_loop> with this watcher. You can only
3174	do this when the watcher is inactive (and not pending either).	3542	do this when the watcher is inactive (and not pending either).
3175		3543
3176	=item w->set ([arguments])	3544	=item w->set ([arguments])
3177		3545
3178	Basically the same as C<ev_TYPE_set>, with the same arguments. Must be	3546	Basically the same as C<ev_TYPE_set>, with the same arguments. Either this
3179	called at least once. Unlike the C counterpart, an active watcher gets	3547	method or a suitable start method must be called at least once. Unlike the
3180	automatically stopped and restarted when reconfiguring it with this	3548	C counterpart, an active watcher gets automatically stopped and restarted
3181	method.	3549	when reconfiguring it with this method.
3182		3550
3183	=item w->start ()	3551	=item w->start ()
3184		3552
3185	Starts the watcher. Note that there is no C<loop> argument, as the	3553	Starts the watcher. Note that there is no C<loop> argument, as the
3186	constructor already stores the event loop.	3554	constructor already stores the event loop.
3187		3555
		3556	=item w->start ([arguments])
		3557
		3558	Instead of calling C<set> and C<start> methods separately, it is often
		3559	convenient to wrap them in one call. Uses the same type of arguments as
		3560	the configure C<set> method of the watcher.
		3561
3188	=item w->stop ()	3562	=item w->stop ()
3189		3563
3190	Stops the watcher if it is active. Again, no C<loop> argument.	3564	Stops the watcher if it is active. Again, no C<loop> argument.
3191		3565
3192	=item w->again () (C<ev::timer>, C<ev::periodic> only)	3566	=item w->again () (C<ev::timer>, C<ev::periodic> only)
…		…
3204		3578
3205	=back	3579	=back
3206		3580
3207	=back	3581	=back
3208		3582
3209	Example: Define a class with an IO and idle watcher, start one of them in	3583	Example: Define a class with two I/O and idle watchers, start the I/O
3210	the constructor.	3584	watchers in the constructor.
3211		3585
3212	class myclass	3586	class myclass
3213	{	3587	{
3214	ev::io io ; void io_cb (ev::io &w, int revents);	3588	ev::io io ; void io_cb (ev::io &w, int revents);
		3589	ev::io2 io2 ; void io2_cb (ev::io &w, int revents);
3215	ev::idle idle; void idle_cb (ev::idle &w, int revents);	3590	ev::idle idle; void idle_cb (ev::idle &w, int revents);
3216		3591
3217	myclass (int fd)	3592	myclass (int fd)
3218	{	3593	{
3219	io .set <myclass, &myclass::io_cb > (this);	3594	io .set <myclass, &myclass::io_cb > (this);
		3595	io2 .set <myclass, &myclass::io2_cb > (this);
3220	idle.set <myclass, &myclass::idle_cb> (this);	3596	idle.set <myclass, &myclass::idle_cb> (this);
3221		3597
3222	io.start (fd, ev::READ);	3598	io.set (fd, ev::WRITE); // configure the watcher
		3599	io.start (); // start it whenever convenient
		3600
		3601	io2.start (fd, ev::READ); // set + start in one call
3223	}	3602	}
3224	};	3603	};
3225		3604
3226		3605
3227	=head1 OTHER LANGUAGE BINDINGS	3606	=head1 OTHER LANGUAGE BINDINGS
…		…
3273	=item Ocaml	3652	=item Ocaml
3274		3653
3275	Erkki Seppala has written Ocaml bindings for libev, to be found at	3654	Erkki Seppala has written Ocaml bindings for libev, to be found at
3276	L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>.	3655	L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>.
3277		3656
		3657	=item Lua
		3658
		3659	Brian Maher has written a partial interface to libev for lua (at the
		3660	time of this writing, only C<ev_io> and C<ev_timer>), to be found at
		3661	L<http://github.com/brimworks/lua-ev>.
		3662
3278	=back	3663	=back
3279		3664
3280		3665
3281	=head1 MACRO MAGIC	3666	=head1 MACRO MAGIC
3282		3667
…		…
3295	loop argument"). The C<EV_A> form is used when this is the sole argument,	3680	loop argument"). The C<EV_A> form is used when this is the sole argument,
3296	C<EV_A_> is used when other arguments are following. Example:	3681	C<EV_A_> is used when other arguments are following. Example:
3297		3682
3298	ev_unref (EV_A);	3683	ev_unref (EV_A);
3299	ev_timer_add (EV_A_ watcher);	3684	ev_timer_add (EV_A_ watcher);
3300	ev_loop (EV_A_ 0);	3685	ev_run (EV_A_ 0);
3301		3686
3302	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	3687	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
3303	which is often provided by the following macro.	3688	which is often provided by the following macro.
3304		3689
3305	=item C<EV_P>, C<EV_P_>	3690	=item C<EV_P>, C<EV_P_>
…		…
3345	}	3730	}
3346		3731
3347	ev_check check;	3732	ev_check check;
3348	ev_check_init (&check, check_cb);	3733	ev_check_init (&check, check_cb);
3349	ev_check_start (EV_DEFAULT_ &check);	3734	ev_check_start (EV_DEFAULT_ &check);
3350	ev_loop (EV_DEFAULT_ 0);	3735	ev_run (EV_DEFAULT_ 0);
3351		3736
3352	=head1 EMBEDDING	3737	=head1 EMBEDDING
3353		3738
3354	Libev can (and often is) directly embedded into host	3739	Libev can (and often is) directly embedded into host
3355	applications. Examples of applications that embed it include the Deliantra	3740	applications. Examples of applications that embed it include the Deliantra
…		…
3435	libev.m4	3820	libev.m4
3436		3821
3437	=head2 PREPROCESSOR SYMBOLS/MACROS	3822	=head2 PREPROCESSOR SYMBOLS/MACROS
3438		3823
3439	Libev can be configured via a variety of preprocessor symbols you have to	3824	Libev can be configured via a variety of preprocessor symbols you have to
3440	define before including any of its files. The default in the absence of	3825	define before including (or compiling) any of its files. The default in
3441	autoconf is documented for every option.	3826	the absence of autoconf is documented for every option.
		3827
		3828	Symbols marked with "(h)" do not change the ABI, and can have different
		3829	values when compiling libev vs. including F<ev.h>, so it is permissible
		3830	to redefine them before including F<ev.h> without breaking compatibility
		3831	to a compiled library. All other symbols change the ABI, which means all
		3832	users of libev and the libev code itself must be compiled with compatible
		3833	settings.
3442		3834
3443	=over 4	3835	=over 4
3444		3836
		3837	=item EV_COMPAT3 (h)
		3838
		3839	Backwards compatibility is a major concern for libev. This is why this
		3840	release of libev comes with wrappers for the functions and symbols that
		3841	have been renamed between libev version 3 and 4.
		3842
		3843	You can disable these wrappers (to test compatibility with future
		3844	versions) by defining C<EV_COMPAT3> to C<0> when compiling your
		3845	sources. This has the additional advantage that you can drop the C<struct>
		3846	from C<struct ev_loop> declarations, as libev will provide an C<ev_loop>
		3847	typedef in that case.
		3848
		3849	In some future version, the default for C<EV_COMPAT3> will become C<0>,
		3850	and in some even more future version the compatibility code will be
		3851	removed completely.
		3852
3445	=item EV_STANDALONE	3853	=item EV_STANDALONE (h)
3446		3854
3447	Must always be C<1> if you do not use autoconf configuration, which	3855	Must always be C<1> if you do not use autoconf configuration, which
3448	keeps libev from including F<config.h>, and it also defines dummy	3856	keeps libev from including F<config.h>, and it also defines dummy
3449	implementations for some libevent functions (such as logging, which is not	3857	implementations for some libevent functions (such as logging, which is not
3450	supported). It will also not define any of the structs usually found in	3858	supported). It will also not define any of the structs usually found in
3451	F<event.h> that are not directly supported by the libev core alone.	3859	F<event.h> that are not directly supported by the libev core alone.
3452		3860
3453	In stanbdalone mode, libev will still try to automatically deduce the	3861	In standalone mode, libev will still try to automatically deduce the
3454	configuration, but has to be more conservative.	3862	configuration, but has to be more conservative.
3455		3863
3456	=item EV_USE_MONOTONIC	3864	=item EV_USE_MONOTONIC
3457		3865
3458	If defined to be C<1>, libev will try to detect the availability of the	3866	If defined to be C<1>, libev will try to detect the availability of the
…		…
3523	be used is the winsock select). This means that it will call	3931	be used is the winsock select). This means that it will call
3524	C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise,	3932	C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise,
3525	it is assumed that all these functions actually work on fds, even	3933	it is assumed that all these functions actually work on fds, even
3526	on win32. Should not be defined on non-win32 platforms.	3934	on win32. Should not be defined on non-win32 platforms.
3527		3935
3528	=item EV_FD_TO_WIN32_HANDLE	3936	=item EV_FD_TO_WIN32_HANDLE(fd)
3529		3937
3530	If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map	3938	If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map
3531	file descriptors to socket handles. When not defining this symbol (the	3939	file descriptors to socket handles. When not defining this symbol (the
3532	default), then libev will call C<_get_osfhandle>, which is usually	3940	default), then libev will call C<_get_osfhandle>, which is usually
3533	correct. In some cases, programs use their own file descriptor management,	3941	correct. In some cases, programs use their own file descriptor management,
3534	in which case they can provide this function to map fds to socket handles.	3942	in which case they can provide this function to map fds to socket handles.
		3943
		3944	=item EV_WIN32_HANDLE_TO_FD(handle)
		3945
		3946	If C<EV_SELECT_IS_WINSOCKET> then libev maps handles to file descriptors
		3947	using the standard C<_open_osfhandle> function. For programs implementing
		3948	their own fd to handle mapping, overwriting this function makes it easier
		3949	to do so. This can be done by defining this macro to an appropriate value.
		3950
		3951	=item EV_WIN32_CLOSE_FD(fd)
		3952
		3953	If programs implement their own fd to handle mapping on win32, then this
		3954	macro can be used to override the C<close> function, useful to unregister
		3955	file descriptors again. Note that the replacement function has to close
		3956	the underlying OS handle.
3535		3957
3536	=item EV_USE_POLL	3958	=item EV_USE_POLL
3537		3959
3538	If defined to be C<1>, libev will compile in support for the C<poll>(2)	3960	If defined to be C<1>, libev will compile in support for the C<poll>(2)
3539	backend. Otherwise it will be enabled on non-win32 platforms. It	3961	backend. Otherwise it will be enabled on non-win32 platforms. It
…		…
3586	as well as for signal and thread safety in C<ev_async> watchers.	4008	as well as for signal and thread safety in C<ev_async> watchers.
3587		4009
3588	In the absence of this define, libev will use C<sig_atomic_t volatile>	4010	In the absence of this define, libev will use C<sig_atomic_t volatile>
3589	(from F<signal.h>), which is usually good enough on most platforms.	4011	(from F<signal.h>), which is usually good enough on most platforms.
3590		4012
3591	=item EV_H	4013	=item EV_H (h)
3592		4014
3593	The name of the F<ev.h> header file used to include it. The default if	4015	The name of the F<ev.h> header file used to include it. The default if
3594	undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be	4016	undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be
3595	used to virtually rename the F<ev.h> header file in case of conflicts.	4017	used to virtually rename the F<ev.h> header file in case of conflicts.
3596		4018
3597	=item EV_CONFIG_H	4019	=item EV_CONFIG_H (h)
3598		4020
3599	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override	4021	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override
3600	F<ev.c>'s idea of where to find the F<config.h> file, similarly to	4022	F<ev.c>'s idea of where to find the F<config.h> file, similarly to
3601	C<EV_H>, above.	4023	C<EV_H>, above.
3602		4024
3603	=item EV_EVENT_H	4025	=item EV_EVENT_H (h)
3604		4026
3605	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea	4027	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea
3606	of how the F<event.h> header can be found, the default is C<"event.h">.	4028	of how the F<event.h> header can be found, the default is C<"event.h">.
3607		4029
3608	=item EV_PROTOTYPES	4030	=item EV_PROTOTYPES (h)
3609		4031
3610	If defined to be C<0>, then F<ev.h> will not define any function	4032	If defined to be C<0>, then F<ev.h> will not define any function
3611	prototypes, but still define all the structs and other symbols. This is	4033	prototypes, but still define all the structs and other symbols. This is
3612	occasionally useful if you want to provide your own wrapper functions	4034	occasionally useful if you want to provide your own wrapper functions
3613	around libev functions.	4035	around libev functions.
…		…
3635	fine.	4057	fine.
3636		4058
3637	If your embedding application does not need any priorities, defining these	4059	If your embedding application does not need any priorities, defining these
3638	both to C<0> will save some memory and CPU.	4060	both to C<0> will save some memory and CPU.
3639		4061
3640	=item EV_PERIODIC_ENABLE	4062	=item EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE,
		4063	EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE,
		4064	EV_ASYNC_ENABLE, EV_CHILD_ENABLE.
3641		4065
3642	If undefined or defined to be C<1>, then periodic timers are supported. If	4066	If undefined or defined to be C<1> (and the platform supports it), then
3643	defined to be C<0>, then they are not. Disabling them saves a few kB of	4067	the respective watcher type is supported. If defined to be C<0>, then it
3644	code.	4068	is not. Disabling watcher types mainly saves code size.
3645		4069
3646	=item EV_IDLE_ENABLE	4070	=item EV_FEATURES
3647
3648	If undefined or defined to be C<1>, then idle watchers are supported. If
3649	defined to be C<0>, then they are not. Disabling them saves a few kB of
3650	code.
3651
3652	=item EV_EMBED_ENABLE
3653
3654	If undefined or defined to be C<1>, then embed watchers are supported. If
3655	defined to be C<0>, then they are not. Embed watchers rely on most other
3656	watcher types, which therefore must not be disabled.
3657
3658	=item EV_STAT_ENABLE
3659
3660	If undefined or defined to be C<1>, then stat watchers are supported. If
3661	defined to be C<0>, then they are not.
3662
3663	=item EV_FORK_ENABLE
3664
3665	If undefined or defined to be C<1>, then fork watchers are supported. If
3666	defined to be C<0>, then they are not.
3667
3668	=item EV_ASYNC_ENABLE
3669
3670	If undefined or defined to be C<1>, then async watchers are supported. If
3671	defined to be C<0>, then they are not.
3672
3673	=item EV_MINIMAL
3674		4071
3675	If you need to shave off some kilobytes of code at the expense of some	4072	If you need to shave off some kilobytes of code at the expense of some
3676	speed, define this symbol to C<1>. Currently this is used to override some	4073	speed (but with the full API), you can define this symbol to request
3677	inlining decisions, saves roughly 30% code size on amd64. It also selects a	4074	certain subsets of functionality. The default is to enable all features
3678	much smaller 2-heap for timer management over the default 4-heap.	4075	that can be enabled on the platform.
		4076
		4077	A typical way to use this symbol is to define it to C<0> (or to a bitset
		4078	with some broad features you want) and then selectively re-enable
		4079	additional parts you want, for example if you want everything minimal,
		4080	but multiple event loop support, async and child watchers and the poll
		4081	backend, use this:
		4082
		4083	#define EV_FEATURES 0
		4084	#define EV_MULTIPLICITY 1
		4085	#define EV_USE_POLL 1
		4086	#define EV_CHILD_ENABLE 1
		4087	#define EV_ASYNC_ENABLE 1
		4088
		4089	The actual value is a bitset, it can be a combination of the following
		4090	values:
		4091
		4092	=over 4
		4093
		4094	=item C<1> - faster/larger code
		4095
		4096	Use larger code to speed up some operations.
		4097
		4098	Currently this is used to override some inlining decisions (enlarging the
		4099	code size by roughly 30% on amd64).
		4100
		4101	When optimising for size, use of compiler flags such as C<-Os> with
		4102	gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of
		4103	assertions.
		4104
		4105	=item C<2> - faster/larger data structures
		4106
		4107	Replaces the small 2-heap for timer management by a faster 4-heap, larger
		4108	hash table sizes and so on. This will usually further increase code size
		4109	and can additionally have an effect on the size of data structures at
		4110	runtime.
		4111
		4112	=item C<4> - full API configuration
		4113
		4114	This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and
		4115	enables multiplicity (C<EV_MULTIPLICITY>=1).
		4116
		4117	=item C<8> - full API
		4118
		4119	This enables a lot of the "lesser used" API functions. See C<ev.h> for
		4120	details on which parts of the API are still available without this
		4121	feature, and do not complain if this subset changes over time.
		4122
		4123	=item C<16> - enable all optional watcher types
		4124
		4125	Enables all optional watcher types. If you want to selectively enable
		4126	only some watcher types other than I/O and timers (e.g. prepare,
		4127	embed, async, child...) you can enable them manually by defining
		4128	C<EV_watchertype_ENABLE> to C<1> instead.
		4129
		4130	=item C<32> - enable all backends
		4131
		4132	This enables all backends - without this feature, you need to enable at
		4133	least one backend manually (C<EV_USE_SELECT> is a good choice).
		4134
		4135	=item C<64> - enable OS-specific "helper" APIs
		4136
		4137	Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by
		4138	default.
		4139
		4140	=back
		4141
		4142	Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0>
		4143	reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb
		4144	code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O
		4145	watchers, timers and monotonic clock support.
		4146
		4147	With an intelligent-enough linker (gcc+binutils are intelligent enough
		4148	when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by
		4149	your program might be left out as well - a binary starting a timer and an
		4150	I/O watcher then might come out at only 5Kb.
		4151
		4152	=item EV_AVOID_STDIO
		4153
		4154	If this is set to C<1> at compiletime, then libev will avoid using stdio
		4155	functions (printf, scanf, perror etc.). This will increase the code size
		4156	somewhat, but if your program doesn't otherwise depend on stdio and your
		4157	libc allows it, this avoids linking in the stdio library which is quite
		4158	big.
		4159
		4160	Note that error messages might become less precise when this option is
		4161	enabled.
		4162
		4163	=item EV_NSIG
		4164
		4165	The highest supported signal number, +1 (or, the number of
		4166	signals): Normally, libev tries to deduce the maximum number of signals
		4167	automatically, but sometimes this fails, in which case it can be
		4168	specified. Also, using a lower number than detected (C<32> should be
		4169	good for about any system in existence) can save some memory, as libev
		4170	statically allocates some 12-24 bytes per signal number.
3679		4171
3680	=item EV_PID_HASHSIZE	4172	=item EV_PID_HASHSIZE
3681		4173
3682	C<ev_child> watchers use a small hash table to distribute workload by	4174	C<ev_child> watchers use a small hash table to distribute workload by
3683	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more	4175	pid. The default size is C<16> (or C<1> with C<EV_FEATURES> disabled),
3684	than enough. If you need to manage thousands of children you might want to	4176	usually more than enough. If you need to manage thousands of children you
3685	increase this value (I<must> be a power of two).	4177	might want to increase this value (I<must> be a power of two).
3686		4178
3687	=item EV_INOTIFY_HASHSIZE	4179	=item EV_INOTIFY_HASHSIZE
3688		4180
3689	C<ev_stat> watchers use a small hash table to distribute workload by	4181	C<ev_stat> watchers use a small hash table to distribute workload by
3690	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),	4182	inotify watch id. The default size is C<16> (or C<1> with C<EV_FEATURES>
3691	usually more than enough. If you need to manage thousands of C<ev_stat>	4183	disabled), usually more than enough. If you need to manage thousands of
3692	watchers you might want to increase this value (I<must> be a power of	4184	C<ev_stat> watchers you might want to increase this value (I<must> be a
3693	two).	4185	power of two).
3694		4186
3695	=item EV_USE_4HEAP	4187	=item EV_USE_4HEAP
3696		4188
3697	Heaps are not very cache-efficient. To improve the cache-efficiency of the	4189	Heaps are not very cache-efficient. To improve the cache-efficiency of the
3698	timer and periodics heaps, libev uses a 4-heap when this symbol is defined	4190	timer and periodics heaps, libev uses a 4-heap when this symbol is defined
3699	to C<1>. The 4-heap uses more complicated (longer) code but has noticeably	4191	to C<1>. The 4-heap uses more complicated (longer) code but has noticeably
3700	faster performance with many (thousands) of watchers.	4192	faster performance with many (thousands) of watchers.
3701		4193
3702	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>	4194	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3703	(disabled).	4195	will be C<0>.
3704		4196
3705	=item EV_HEAP_CACHE_AT	4197	=item EV_HEAP_CACHE_AT
3706		4198
3707	Heaps are not very cache-efficient. To improve the cache-efficiency of the	4199	Heaps are not very cache-efficient. To improve the cache-efficiency of the
3708	timer and periodics heaps, libev can cache the timestamp (I<at>) within	4200	timer and periodics heaps, libev can cache the timestamp (I<at>) within
3709	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),	4201	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),
3710	which uses 8-12 bytes more per watcher and a few hundred bytes more code,	4202	which uses 8-12 bytes more per watcher and a few hundred bytes more code,
3711	but avoids random read accesses on heap changes. This improves performance	4203	but avoids random read accesses on heap changes. This improves performance
3712	noticeably with many (hundreds) of watchers.	4204	noticeably with many (hundreds) of watchers.
3713		4205
3714	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>	4206	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3715	(disabled).	4207	will be C<0>.
3716		4208
3717	=item EV_VERIFY	4209	=item EV_VERIFY
3718		4210
3719	Controls how much internal verification (see C<ev_loop_verify ()>) will	4211	Controls how much internal verification (see C<ev_verify ()>) will
3720	be done: If set to C<0>, no internal verification code will be compiled	4212	be done: If set to C<0>, no internal verification code will be compiled
3721	in. If set to C<1>, then verification code will be compiled in, but not	4213	in. If set to C<1>, then verification code will be compiled in, but not
3722	called. If set to C<2>, then the internal verification code will be	4214	called. If set to C<2>, then the internal verification code will be
3723	called once per loop, which can slow down libev. If set to C<3>, then the	4215	called once per loop, which can slow down libev. If set to C<3>, then the
3724	verification code will be called very frequently, which will slow down	4216	verification code will be called very frequently, which will slow down
3725	libev considerably.	4217	libev considerably.
3726		4218
3727	The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be	4219	The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it
3728	C<0>.	4220	will be C<0>.
3729		4221
3730	=item EV_COMMON	4222	=item EV_COMMON
3731		4223
3732	By default, all watchers have a C<void *data> member. By redefining	4224	By default, all watchers have a C<void *data> member. By redefining
3733	this macro to a something else you can include more and other types of	4225	this macro to something else you can include more and other types of
3734	members. You have to define it each time you include one of the files,	4226	members. You have to define it each time you include one of the files,
3735	though, and it must be identical each time.	4227	though, and it must be identical each time.
3736		4228
3737	For example, the perl EV module uses something like this:	4229	For example, the perl EV module uses something like this:
3738		4230
…		…
3791	file.	4283	file.
3792		4284
3793	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	4285	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
3794	that everybody includes and which overrides some configure choices:	4286	that everybody includes and which overrides some configure choices:
3795		4287
3796	#define EV_MINIMAL 1	4288	#define EV_FEATURES 8
3797	#define EV_USE_POLL 0	4289	#define EV_USE_SELECT 1
3798	#define EV_MULTIPLICITY 0
3799	#define EV_PERIODIC_ENABLE 0	4290	#define EV_PREPARE_ENABLE 1
		4291	#define EV_IDLE_ENABLE 1
3800	#define EV_STAT_ENABLE 0	4292	#define EV_SIGNAL_ENABLE 1
3801	#define EV_FORK_ENABLE 0	4293	#define EV_CHILD_ENABLE 1
		4294	#define EV_USE_STDEXCEPT 0
3802	#define EV_CONFIG_H <config.h>	4295	#define EV_CONFIG_H <config.h>
3803	#define EV_MINPRI 0
3804	#define EV_MAXPRI 0
3805		4296
3806	#include "ev++.h"	4297	#include "ev++.h"
3807		4298
3808	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	4299	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
3809		4300
…		…
3869	default loop and triggering an C<ev_async> watcher from the default loop	4360	default loop and triggering an C<ev_async> watcher from the default loop
3870	watcher callback into the event loop interested in the signal.	4361	watcher callback into the event loop interested in the signal.
3871		4362
3872	=back	4363	=back
3873		4364
		4365	=head4 THREAD LOCKING EXAMPLE
		4366
		4367	Here is a fictitious example of how to run an event loop in a different
		4368	thread than where callbacks are being invoked and watchers are
		4369	created/added/removed.
		4370
		4371	For a real-world example, see the C<EV::Loop::Async> perl module,
		4372	which uses exactly this technique (which is suited for many high-level
		4373	languages).
		4374
		4375	The example uses a pthread mutex to protect the loop data, a condition
		4376	variable to wait for callback invocations, an async watcher to notify the
		4377	event loop thread and an unspecified mechanism to wake up the main thread.
		4378
		4379	First, you need to associate some data with the event loop:
		4380
		4381	typedef struct {
		4382	mutex_t lock; /* global loop lock */
		4383	ev_async async_w;
		4384	thread_t tid;
		4385	cond_t invoke_cv;
		4386	} userdata;
		4387
		4388	void prepare_loop (EV_P)
		4389	{
		4390	// for simplicity, we use a static userdata struct.
		4391	static userdata u;
		4392
		4393	ev_async_init (&u->async_w, async_cb);
		4394	ev_async_start (EV_A_ &u->async_w);
		4395
		4396	pthread_mutex_init (&u->lock, 0);
		4397	pthread_cond_init (&u->invoke_cv, 0);
		4398
		4399	// now associate this with the loop
		4400	ev_set_userdata (EV_A_ u);
		4401	ev_set_invoke_pending_cb (EV_A_ l_invoke);
		4402	ev_set_loop_release_cb (EV_A_ l_release, l_acquire);
		4403
		4404	// then create the thread running ev_loop
		4405	pthread_create (&u->tid, 0, l_run, EV_A);
		4406	}
		4407
		4408	The callback for the C<ev_async> watcher does nothing: the watcher is used
		4409	solely to wake up the event loop so it takes notice of any new watchers
		4410	that might have been added:
		4411
		4412	static void
		4413	async_cb (EV_P_ ev_async *w, int revents)
		4414	{
		4415	// just used for the side effects
		4416	}
		4417
		4418	The C<l_release> and C<l_acquire> callbacks simply unlock/lock the mutex
		4419	protecting the loop data, respectively.
		4420
		4421	static void
		4422	l_release (EV_P)
		4423	{
		4424	userdata *u = ev_userdata (EV_A);
		4425	pthread_mutex_unlock (&u->lock);
		4426	}
		4427
		4428	static void
		4429	l_acquire (EV_P)
		4430	{
		4431	userdata *u = ev_userdata (EV_A);
		4432	pthread_mutex_lock (&u->lock);
		4433	}
		4434
		4435	The event loop thread first acquires the mutex, and then jumps straight
		4436	into C<ev_run>:
		4437
		4438	void *
		4439	l_run (void *thr_arg)
		4440	{
		4441	struct ev_loop *loop = (struct ev_loop *)thr_arg;
		4442
		4443	l_acquire (EV_A);
		4444	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0);
		4445	ev_run (EV_A_ 0);
		4446	l_release (EV_A);
		4447
		4448	return 0;
		4449	}
		4450
		4451	Instead of invoking all pending watchers, the C<l_invoke> callback will
		4452	signal the main thread via some unspecified mechanism (signals? pipe
		4453	writes? C<Async::Interrupt>?) and then waits until all pending watchers
		4454	have been called (in a while loop because a) spurious wakeups are possible
		4455	and b) skipping inter-thread-communication when there are no pending
		4456	watchers is very beneficial):
		4457
		4458	static void
		4459	l_invoke (EV_P)
		4460	{
		4461	userdata *u = ev_userdata (EV_A);
		4462
		4463	while (ev_pending_count (EV_A))
		4464	{
		4465	wake_up_other_thread_in_some_magic_or_not_so_magic_way ();
		4466	pthread_cond_wait (&u->invoke_cv, &u->lock);
		4467	}
		4468	}
		4469
		4470	Now, whenever the main thread gets told to invoke pending watchers, it
		4471	will grab the lock, call C<ev_invoke_pending> and then signal the loop
		4472	thread to continue:
		4473
		4474	static void
		4475	real_invoke_pending (EV_P)
		4476	{
		4477	userdata *u = ev_userdata (EV_A);
		4478
		4479	pthread_mutex_lock (&u->lock);
		4480	ev_invoke_pending (EV_A);
		4481	pthread_cond_signal (&u->invoke_cv);
		4482	pthread_mutex_unlock (&u->lock);
		4483	}
		4484
		4485	Whenever you want to start/stop a watcher or do other modifications to an
		4486	event loop, you will now have to lock:
		4487
		4488	ev_timer timeout_watcher;
		4489	userdata *u = ev_userdata (EV_A);
		4490
		4491	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
		4492
		4493	pthread_mutex_lock (&u->lock);
		4494	ev_timer_start (EV_A_ &timeout_watcher);
		4495	ev_async_send (EV_A_ &u->async_w);
		4496	pthread_mutex_unlock (&u->lock);
		4497
		4498	Note that sending the C<ev_async> watcher is required because otherwise
		4499	an event loop currently blocking in the kernel will have no knowledge
		4500	about the newly added timer. By waking up the loop it will pick up any new
		4501	watchers in the next event loop iteration.
		4502
3874	=head3 COROUTINES	4503	=head3 COROUTINES
3875		4504
3876	Libev is very accommodating to coroutines ("cooperative threads"):	4505	Libev is very accommodating to coroutines ("cooperative threads"):
3877	libev fully supports nesting calls to its functions from different	4506	libev fully supports nesting calls to its functions from different
3878	coroutines (e.g. you can call C<ev_loop> on the same loop from two	4507	coroutines (e.g. you can call C<ev_run> on the same loop from two
3879	different coroutines, and switch freely between both coroutines running the	4508	different coroutines, and switch freely between both coroutines running
3880	loop, as long as you don't confuse yourself). The only exception is that	4509	the loop, as long as you don't confuse yourself). The only exception is
3881	you must not do this from C<ev_periodic> reschedule callbacks.	4510	that you must not do this from C<ev_periodic> reschedule callbacks.
3882		4511
3883	Care has been taken to ensure that libev does not keep local state inside	4512	Care has been taken to ensure that libev does not keep local state inside
3884	C<ev_loop>, and other calls do not usually allow for coroutine switches as	4513	C<ev_run>, and other calls do not usually allow for coroutine switches as
3885	they do not call any callbacks.	4514	they do not call any callbacks.
3886		4515
3887	=head2 COMPILER WARNINGS	4516	=head2 COMPILER WARNINGS
3888		4517
3889	Depending on your compiler and compiler settings, you might get no or a	4518	Depending on your compiler and compiler settings, you might get no or a
…		…
3900	maintainable.	4529	maintainable.
3901		4530
3902	And of course, some compiler warnings are just plain stupid, or simply	4531	And of course, some compiler warnings are just plain stupid, or simply
3903	wrong (because they don't actually warn about the condition their message	4532	wrong (because they don't actually warn about the condition their message
3904	seems to warn about). For example, certain older gcc versions had some	4533	seems to warn about). For example, certain older gcc versions had some
3905	warnings that resulted an extreme number of false positives. These have	4534	warnings that resulted in an extreme number of false positives. These have
3906	been fixed, but some people still insist on making code warn-free with	4535	been fixed, but some people still insist on making code warn-free with
3907	such buggy versions.	4536	such buggy versions.
3908		4537
3909	While libev is written to generate as few warnings as possible,	4538	While libev is written to generate as few warnings as possible,
3910	"warn-free" code is not a goal, and it is recommended not to build libev	4539	"warn-free" code is not a goal, and it is recommended not to build libev
…		…
3946	I suggest using suppression lists.	4575	I suggest using suppression lists.
3947		4576
3948		4577
3949	=head1 PORTABILITY NOTES	4578	=head1 PORTABILITY NOTES
3950		4579
		4580	=head2 GNU/LINUX 32 BIT LIMITATIONS
		4581
		4582	GNU/Linux is the only common platform that supports 64 bit file/large file
		4583	interfaces but I<disables> them by default.
		4584
		4585	That means that libev compiled in the default environment doesn't support
		4586	files larger than 2GiB or so, which mainly affects C<ev_stat> watchers.
		4587
		4588	Unfortunately, many programs try to work around this GNU/Linux issue
		4589	by enabling the large file API, which makes them incompatible with the
		4590	standard libev compiled for their system.
		4591
		4592	Likewise, libev cannot enable the large file API itself as this would
		4593	suddenly make it incompatible to the default compile time environment,
		4594	i.e. all programs not using special compile switches.
		4595
		4596	=head2 OS/X AND DARWIN BUGS
		4597
		4598	The whole thing is a bug if you ask me - basically any system interface
		4599	you touch is broken, whether it is locales, poll, kqueue or even the
		4600	OpenGL drivers.
		4601
		4602	=head3 C<kqueue> is buggy
		4603
		4604	The kqueue syscall is broken in all known versions - most versions support
		4605	only sockets, many support pipes.
		4606
		4607	Libev tries to work around this by not using C<kqueue> by default on this
		4608	rotten platform, but of course you can still ask for it when creating a
		4609	loop - embedding a socket-only kqueue loop into a select-based one is
		4610	probably going to work well.
		4611
		4612	=head3 C<poll> is buggy
		4613
		4614	Instead of fixing C<kqueue>, Apple replaced their (working) C<poll>
		4615	implementation by something calling C<kqueue> internally around the 10.5.6
		4616	release, so now C<kqueue> I<and> C<poll> are broken.
		4617
		4618	Libev tries to work around this by not using C<poll> by default on
		4619	this rotten platform, but of course you can still ask for it when creating
		4620	a loop.
		4621
		4622	=head3 C<select> is buggy
		4623
		4624	All that's left is C<select>, and of course Apple found a way to fuck this
		4625	one up as well: On OS/X, C<select> actively limits the number of file
		4626	descriptors you can pass in to 1024 - your program suddenly crashes when
		4627	you use more.
		4628
		4629	There is an undocumented "workaround" for this - defining
		4630	C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should>
		4631	work on OS/X.
		4632
		4633	=head2 SOLARIS PROBLEMS AND WORKAROUNDS
		4634
		4635	=head3 C<errno> reentrancy
		4636
		4637	The default compile environment on Solaris is unfortunately so
		4638	thread-unsafe that you can't even use components/libraries compiled
		4639	without C<-D_REENTRANT> in a threaded program, which, of course, isn't
		4640	defined by default. A valid, if stupid, implementation choice.
		4641
		4642	If you want to use libev in threaded environments you have to make sure
		4643	it's compiled with C<_REENTRANT> defined.
		4644
		4645	=head3 Event port backend
		4646
		4647	The scalable event interface for Solaris is called "event
		4648	ports". Unfortunately, this mechanism is very buggy in all major
		4649	releases. If you run into high CPU usage, your program freezes or you get
		4650	a large number of spurious wakeups, make sure you have all the relevant
		4651	and latest kernel patches applied. No, I don't know which ones, but there
		4652	are multiple ones to apply, and afterwards, event ports actually work
		4653	great.
		4654
		4655	If you can't get it to work, you can try running the program by setting
		4656	the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and
		4657	C<select> backends.
		4658
		4659	=head2 AIX POLL BUG
		4660
		4661	AIX unfortunately has a broken C<poll.h> header. Libev works around
		4662	this by trying to avoid the poll backend altogether (i.e. it's not even
		4663	compiled in), which normally isn't a big problem as C<select> works fine
		4664	with large bitsets on AIX, and AIX is dead anyway.
		4665
3951	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS	4666	=head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
		4667
		4668	=head3 General issues
3952		4669
3953	Win32 doesn't support any of the standards (e.g. POSIX) that libev	4670	Win32 doesn't support any of the standards (e.g. POSIX) that libev
3954	requires, and its I/O model is fundamentally incompatible with the POSIX	4671	requires, and its I/O model is fundamentally incompatible with the POSIX
3955	model. Libev still offers limited functionality on this platform in	4672	model. Libev still offers limited functionality on this platform in
3956	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	4673	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
3957	descriptors. This only applies when using Win32 natively, not when using	4674	descriptors. This only applies when using Win32 natively, not when using
3958	e.g. cygwin.	4675	e.g. cygwin. Actually, it only applies to the microsofts own compilers,
		4676	as every compielr comes with a slightly differently broken/incompatible
		4677	environment.
3959		4678
3960	Lifting these limitations would basically require the full	4679	Lifting these limitations would basically require the full
3961	re-implementation of the I/O system. If you are into these kinds of	4680	re-implementation of the I/O system. If you are into this kind of thing,
3962	things, then note that glib does exactly that for you in a very portable	4681	then note that glib does exactly that for you in a very portable way (note
3963	way (note also that glib is the slowest event library known to man).	4682	also that glib is the slowest event library known to man).
3964		4683
3965	There is no supported compilation method available on windows except	4684	There is no supported compilation method available on windows except
3966	embedding it into other applications.	4685	embedding it into other applications.
3967		4686
3968	Sensible signal handling is officially unsupported by Microsoft - libev	4687	Sensible signal handling is officially unsupported by Microsoft - libev
…		…
3996	you do I<not> compile the F<ev.c> or any other embedded source files!):	4715	you do I<not> compile the F<ev.c> or any other embedded source files!):
3997		4716
3998	#include "evwrap.h"	4717	#include "evwrap.h"
3999	#include "ev.c"	4718	#include "ev.c"
4000		4719
4001	=over 4
4002
4003	=item The winsocket select function	4720	=head3 The winsocket C<select> function
4004		4721
4005	The winsocket C<select> function doesn't follow POSIX in that it	4722	The winsocket C<select> function doesn't follow POSIX in that it
4006	requires socket I<handles> and not socket I<file descriptors> (it is	4723	requires socket I<handles> and not socket I<file descriptors> (it is
4007	also extremely buggy). This makes select very inefficient, and also	4724	also extremely buggy). This makes select very inefficient, and also
4008	requires a mapping from file descriptors to socket handles (the Microsoft	4725	requires a mapping from file descriptors to socket handles (the Microsoft
…		…
4017	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */	4734	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
4018		4735
4019	Note that winsockets handling of fd sets is O(n), so you can easily get a	4736	Note that winsockets handling of fd sets is O(n), so you can easily get a
4020	complexity in the O(n²) range when using win32.	4737	complexity in the O(n²) range when using win32.
4021		4738
4022	=item Limited number of file descriptors	4739	=head3 Limited number of file descriptors
4023		4740
4024	Windows has numerous arbitrary (and low) limits on things.	4741	Windows has numerous arbitrary (and low) limits on things.
4025		4742
4026	Early versions of winsocket's select only supported waiting for a maximum	4743	Early versions of winsocket's select only supported waiting for a maximum
4027	of C<64> handles (probably owning to the fact that all windows kernels	4744	of C<64> handles (probably owning to the fact that all windows kernels
…		…
4042	runtime libraries. This might get you to about C<512> or C<2048> sockets	4759	runtime libraries. This might get you to about C<512> or C<2048> sockets
4043	(depending on windows version and/or the phase of the moon). To get more,	4760	(depending on windows version and/or the phase of the moon). To get more,
4044	you need to wrap all I/O functions and provide your own fd management, but	4761	you need to wrap all I/O functions and provide your own fd management, but
4045	the cost of calling select (O(n²)) will likely make this unworkable.	4762	the cost of calling select (O(n²)) will likely make this unworkable.
4046		4763
4047	=back
4048
4049	=head2 PORTABILITY REQUIREMENTS	4764	=head2 PORTABILITY REQUIREMENTS
4050		4765
4051	In addition to a working ISO-C implementation and of course the	4766	In addition to a working ISO-C implementation and of course the
4052	backend-specific APIs, libev relies on a few additional extensions:	4767	backend-specific APIs, libev relies on a few additional extensions:
4053		4768
…		…
4059	Libev assumes not only that all watcher pointers have the same internal	4774	Libev assumes not only that all watcher pointers have the same internal
4060	structure (guaranteed by POSIX but not by ISO C for example), but it also	4775	structure (guaranteed by POSIX but not by ISO C for example), but it also
4061	assumes that the same (machine) code can be used to call any watcher	4776	assumes that the same (machine) code can be used to call any watcher
4062	callback: The watcher callbacks have different type signatures, but libev	4777	callback: The watcher callbacks have different type signatures, but libev
4063	calls them using an C<ev_watcher *> internally.	4778	calls them using an C<ev_watcher *> internally.
		4779
		4780	=item pointer accesses must be thread-atomic
		4781
		4782	Accessing a pointer value must be atomic, it must both be readable and
		4783	writable in one piece - this is the case on all current architectures.
4064		4784
4065	=item C<sig_atomic_t volatile> must be thread-atomic as well	4785	=item C<sig_atomic_t volatile> must be thread-atomic as well
4066		4786
4067	The type C<sig_atomic_t volatile> (or whatever is defined as	4787	The type C<sig_atomic_t volatile> (or whatever is defined as
4068	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different	4788	C<EV_ATOMIC_T>) must be atomic with respect to accesses from different
…		…
4091	watchers.	4811	watchers.
4092		4812
4093	=item C<double> must hold a time value in seconds with enough accuracy	4813	=item C<double> must hold a time value in seconds with enough accuracy
4094		4814
4095	The type C<double> is used to represent timestamps. It is required to	4815	The type C<double> is used to represent timestamps. It is required to
4096	have at least 51 bits of mantissa (and 9 bits of exponent), which is good	4816	have at least 51 bits of mantissa (and 9 bits of exponent), which is
4097	enough for at least into the year 4000. This requirement is fulfilled by	4817	good enough for at least into the year 4000 with millisecond accuracy
		4818	(the design goal for libev). This requirement is overfulfilled by
4098	implementations implementing IEEE 754, which is basically all existing	4819	implementations using IEEE 754, which is basically all existing ones. With
4099	ones. With IEEE 754 doubles, you get microsecond accuracy until at least	4820	IEEE 754 doubles, you get microsecond accuracy until at least 2200.
4100	2200.
4101		4821
4102	=back	4822	=back
4103		4823
4104	If you know of other additional requirements drop me a note.	4824	If you know of other additional requirements drop me a note.
4105		4825
…		…
4173	involves iterating over all running async watchers or all signal numbers.	4893	involves iterating over all running async watchers or all signal numbers.
4174		4894
4175	=back	4895	=back
4176		4896
4177		4897
		4898	=head1 PORTING FROM LIBEV 3.X TO 4.X
		4899
		4900	The major version 4 introduced some incompatible changes to the API.
		4901
		4902	At the moment, the C<ev.h> header file provides compatibility definitions
		4903	for all changes, so most programs should still compile. The compatibility
		4904	layer might be removed in later versions of libev, so better update to the
		4905	new API early than late.
		4906
		4907	=over 4
		4908
		4909	=item C<EV_COMPAT3> backwards compatibility mechanism
		4910
		4911	The backward compatibility mechanism can be controlled by
		4912	C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING>
		4913	section.
		4914
		4915	=item C<ev_default_destroy> and C<ev_default_fork> have been removed
		4916
		4917	These calls can be replaced easily by their C<ev_loop_xxx> counterparts:
		4918
		4919	ev_loop_destroy (EV_DEFAULT_UC);
		4920	ev_loop_fork (EV_DEFAULT);
		4921
		4922	=item function/symbol renames
		4923
		4924	A number of functions and symbols have been renamed:
		4925
		4926	ev_loop => ev_run
		4927	EVLOOP_NONBLOCK => EVRUN_NOWAIT
		4928	EVLOOP_ONESHOT => EVRUN_ONCE
		4929
		4930	ev_unloop => ev_break
		4931	EVUNLOOP_CANCEL => EVBREAK_CANCEL
		4932	EVUNLOOP_ONE => EVBREAK_ONE
		4933	EVUNLOOP_ALL => EVBREAK_ALL
		4934
		4935	EV_TIMEOUT => EV_TIMER
		4936
		4937	ev_loop_count => ev_iteration
		4938	ev_loop_depth => ev_depth
		4939	ev_loop_verify => ev_verify
		4940
		4941	Most functions working on C<struct ev_loop> objects don't have an
		4942	C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and
		4943	associated constants have been renamed to not collide with the C<struct
		4944	ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme
		4945	as all other watcher types. Note that C<ev_loop_fork> is still called
		4946	C<ev_loop_fork> because it would otherwise clash with the C<ev_fork>
		4947	typedef.
		4948
		4949	=item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES>
		4950
		4951	The preprocessor symbol C<EV_MINIMAL> has been replaced by a different
		4952	mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile
		4953	and work, but the library code will of course be larger.
		4954
		4955	=back
		4956
		4957
4178	=head1 GLOSSARY	4958	=head1 GLOSSARY
4179		4959
4180	=over 4	4960	=over 4
4181		4961
4182	=item active	4962	=item active
4183		4963
4184	A watcher is active as long as it has been started (has been attached to	4964	A watcher is active as long as it has been started and not yet stopped.
4185	an event loop) but not yet stopped (disassociated from the event loop).	4965	See L<WATCHER STATES> for details.
4186		4966
4187	=item application	4967	=item application
4188		4968
4189	In this document, an application is whatever is using libev.	4969	In this document, an application is whatever is using libev.
		4970
		4971	=item backend
		4972
		4973	The part of the code dealing with the operating system interfaces.
4190		4974
4191	=item callback	4975	=item callback
4192		4976
4193	The address of a function that is called when some event has been	4977	The address of a function that is called when some event has been
4194	detected. Callbacks are being passed the event loop, the watcher that	4978	detected. Callbacks are being passed the event loop, the watcher that
4195	received the event, and the actual event bitset.	4979	received the event, and the actual event bitset.
4196		4980
4197	=item callback invocation	4981	=item callback/watcher invocation
4198		4982
4199	The act of calling the callback associated with a watcher.	4983	The act of calling the callback associated with a watcher.
4200		4984
4201	=item event	4985	=item event
4202		4986
4203	A change of state of some external event, such as data now being available	4987	A change of state of some external event, such as data now being available
4204	for reading on a file descriptor, time having passed or simply not having	4988	for reading on a file descriptor, time having passed or simply not having
4205	any other events happening anymore.	4989	any other events happening anymore.
4206		4990
4207	In libev, events are represented as single bits (such as C<EV_READ> or	4991	In libev, events are represented as single bits (such as C<EV_READ> or
4208	C<EV_TIMEOUT>).	4992	C<EV_TIMER>).
4209		4993
4210	=item event library	4994	=item event library
4211		4995
4212	A software package implementing an event model and loop.	4996	A software package implementing an event model and loop.
4213		4997
…		…
4221	The model used to describe how an event loop handles and processes	5005	The model used to describe how an event loop handles and processes
4222	watchers and events.	5006	watchers and events.
4223		5007
4224	=item pending	5008	=item pending
4225		5009
4226	A watcher is pending as soon as the corresponding event has been detected,	5010	A watcher is pending as soon as the corresponding event has been
4227	and stops being pending as soon as the watcher will be invoked or its	5011	detected. See L<WATCHER STATES> for details.
4228	pending status is explicitly cleared by the application.
4229
4230	A watcher can be pending, but not active. Stopping a watcher also clears
4231	its pending status.
4232		5012
4233	=item real time	5013	=item real time
4234		5014
4235	The physical time that is observed. It is apparently strictly monotonic :)	5015	The physical time that is observed. It is apparently strictly monotonic :)
4236		5016
…		…
4243	=item watcher	5023	=item watcher
4244		5024
4245	A data structure that describes interest in certain events. Watchers need	5025	A data structure that describes interest in certain events. Watchers need
4246	to be started (attached to an event loop) before they can receive events.	5026	to be started (attached to an event loop) before they can receive events.
4247		5027
4248	=item watcher invocation
4249
4250	The act of calling the callback associated with a watcher.
4251
4252	=back	5028	=back
4253		5029
4254	=head1 AUTHOR	5030	=head1 AUTHOR
4255		5031
4256	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson.	5032	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael
		5033	Magnusson and Emanuele Giaquinta.
4257		5034

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