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…		…
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	#include <ev.h>	7	#include <ev.h>
8		8
9	=head1 EXAMPLE PROGRAM	9	=head2 EXAMPLE PROGRAM
10		10
		11	// a single header file is required
11	#include <ev.h>	12	#include <ev.h>
12		13
		14	// every watcher type has its own typedef'd struct
		15	// with the name ev_<type>
13	ev_io stdin_watcher;	16	ev_io stdin_watcher;
14	ev_timer timeout_watcher;	17	ev_timer timeout_watcher;
15		18
		19	// all watcher callbacks have a similar signature
16	/* called when data readable on stdin */	20	// this callback is called when data is readable on stdin
17	static void	21	static void
18	stdin_cb (EV_P_ struct ev_io *w, int revents)	22	stdin_cb (EV_P_ struct ev_io *w, int revents)
19	{	23	{
20	/* puts ("stdin ready"); */	24	puts ("stdin ready");
21	ev_io_stop (EV_A_ w); /* just a syntax example */	25	// for one-shot events, one must manually stop the watcher
22	ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */	26	// with its corresponding stop function.
		27	ev_io_stop (EV_A_ w);
		28
		29	// this causes all nested ev_loop's to stop iterating
		30	ev_unloop (EV_A_ EVUNLOOP_ALL);
23	}	31	}
24		32
		33	// another callback, this time for a time-out
25	static void	34	static void
26	timeout_cb (EV_P_ struct ev_timer *w, int revents)	35	timeout_cb (EV_P_ struct ev_timer *w, int revents)
27	{	36	{
28	/* puts ("timeout"); */	37	puts ("timeout");
29	ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */	38	// this causes the innermost ev_loop to stop iterating
		39	ev_unloop (EV_A_ EVUNLOOP_ONE);
30	}	40	}
31		41
32	int	42	int
33	main (void)	43	main (void)
34	{	44	{
		45	// use the default event loop unless you have special needs
35	struct ev_loop *loop = ev_default_loop (0);	46	struct ev_loop *loop = ev_default_loop (0);
36		47
37	/* initialise an io watcher, then start it */	48	// initialise an io watcher, then start it
		49	// this one will watch for stdin to become readable
38	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);	50	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);
39	ev_io_start (loop, &stdin_watcher);	51	ev_io_start (loop, &stdin_watcher);
40		52
		53	// initialise a timer watcher, then start it
41	/* simple non-repeating 5.5 second timeout */	54	// simple non-repeating 5.5 second timeout
42	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);	55	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
43	ev_timer_start (loop, &timeout_watcher);	56	ev_timer_start (loop, &timeout_watcher);
44		57
45	/* loop till timeout or data ready */	58	// now wait for events to arrive
46	ev_loop (loop, 0);	59	ev_loop (loop, 0);
47		60
		61	// unloop was called, so exit
48	return 0;	62	return 0;
49	}	63	}
50		64
51	=head1 DESCRIPTION	65	=head1 DESCRIPTION
52		66
		67	The newest version of this document is also available as an html-formatted
		68	web page you might find easier to navigate when reading it for the first
		69	time: L<http://cvs.schmorp.de/libev/ev.html>.
		70
53	Libev is an event loop: you register interest in certain events (such as a	71	Libev is an event loop: you register interest in certain events (such as a
54	file descriptor being readable or a timeout occuring), and it will manage	72	file descriptor being readable or a timeout occurring), and it will manage
55	these event sources and provide your program with events.	73	these event sources and provide your program with events.
56		74
57	To do this, it must take more or less complete control over your process	75	To do this, it must take more or less complete control over your process
58	(or thread) by executing the I<event loop> handler, and will then	76	(or thread) by executing the I<event loop> handler, and will then
59	communicate events via a callback mechanism.	77	communicate events via a callback mechanism.
…		…
61	You register interest in certain events by registering so-called I<event	79	You register interest in certain events by registering so-called I<event
62	watchers>, which are relatively small C structures you initialise with the	80	watchers>, which are relatively small C structures you initialise with the
63	details of the event, and then hand it over to libev by I<starting> the	81	details of the event, and then hand it over to libev by I<starting> the
64	watcher.	82	watcher.
65		83
66	=head1 FEATURES	84	=head2 FEATURES
67		85
68	Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the	86	Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the
69	BSD-specific C<kqueue> and the Solaris-specific event port mechanisms	87	BSD-specific C<kqueue> and the Solaris-specific event port mechanisms
70	for file descriptor events (C<ev_io>), the Linux C<inotify> interface	88	for file descriptor events (C<ev_io>), the Linux C<inotify> interface
71	(for C<ev_stat>), relative timers (C<ev_timer>), absolute timers	89	(for C<ev_stat>), relative timers (C<ev_timer>), absolute timers
…		…
78		96
79	It also is quite fast (see this	97	It also is quite fast (see this
80	L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent	98	L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent
81	for example).	99	for example).
82		100
83	=head1 CONVENTIONS	101	=head2 CONVENTIONS
84		102
85	Libev is very configurable. In this manual the default configuration will	103	Libev is very configurable. In this manual the default (and most common)
86	be described, which supports multiple event loops. For more info about	104	configuration will be described, which supports multiple event loops. For
87	various configuration options please have a look at B<EMBED> section in	105	more info about various configuration options please have a look at
88	this manual. If libev was configured without support for multiple event	106	B<EMBED> section in this manual. If libev was configured without support
89	loops, then all functions taking an initial argument of name C<loop>	107	for multiple event loops, then all functions taking an initial argument of
90	(which is always of type C<struct ev_loop *>) will not have this argument.	108	name C<loop> (which is always of type C<struct ev_loop *>) will not have
		109	this argument.
91		110
92	=head1 TIME REPRESENTATION	111	=head2 TIME REPRESENTATION
93		112
94	Libev represents time as a single floating point number, representing the	113	Libev represents time as a single floating point number, representing the
95	(fractional) number of seconds since the (POSIX) epoch (somewhere near	114	(fractional) number of seconds since the (POSIX) epoch (somewhere near
96	the beginning of 1970, details are complicated, don't ask). This type is	115	the beginning of 1970, details are complicated, don't ask). This type is
97	called C<ev_tstamp>, which is what you should use too. It usually aliases	116	called C<ev_tstamp>, which is what you should use too. It usually aliases
98	to the C<double> type in C, and when you need to do any calculations on	117	to the C<double> type in C, and when you need to do any calculations on
99	it, you should treat it as such.	118	it, you should treat it as some floatingpoint value. Unlike the name
		119	component C<stamp> might indicate, it is also used for time differences
		120	throughout libev.
100		121
101	=head1 GLOBAL FUNCTIONS	122	=head1 GLOBAL FUNCTIONS
102		123
103	These functions can be called anytime, even before initialising the	124	These functions can be called anytime, even before initialising the
104	library in any way.	125	library in any way.
…		…
109		130
110	Returns the current time as libev would use it. Please note that the	131	Returns the current time as libev would use it. Please note that the
111	C<ev_now> function is usually faster and also often returns the timestamp	132	C<ev_now> function is usually faster and also often returns the timestamp
112	you actually want to know.	133	you actually want to know.
113		134
		135	=item ev_sleep (ev_tstamp interval)
		136
		137	Sleep for the given interval: The current thread will be blocked until
		138	either it is interrupted or the given time interval has passed. Basically
		139	this is a subsecond-resolution C<sleep ()>.
		140
114	=item int ev_version_major ()	141	=item int ev_version_major ()
115		142
116	=item int ev_version_minor ()	143	=item int ev_version_minor ()
117		144
118	You can find out the major and minor version numbers of the library	145	You can find out the major and minor ABI version numbers of the library
119	you linked against by calling the functions C<ev_version_major> and	146	you linked against by calling the functions C<ev_version_major> and
120	C<ev_version_minor>. If you want, you can compare against the global	147	C<ev_version_minor>. If you want, you can compare against the global
121	symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the	148	symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the
122	version of the library your program was compiled against.	149	version of the library your program was compiled against.
123		150
		151	These version numbers refer to the ABI version of the library, not the
		152	release version.
		153
124	Usually, it's a good idea to terminate if the major versions mismatch,	154	Usually, it's a good idea to terminate if the major versions mismatch,
125	as this indicates an incompatible change. Minor versions are usually	155	as this indicates an incompatible change. Minor versions are usually
126	compatible to older versions, so a larger minor version alone is usually	156	compatible to older versions, so a larger minor version alone is usually
127	not a problem.	157	not a problem.
128		158
129	Example: Make sure we haven't accidentally been linked against the wrong	159	Example: Make sure we haven't accidentally been linked against the wrong
130	version.	160	version.
…		…
163	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for	193	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for
164	recommended ones.	194	recommended ones.
165		195
166	See the description of C<ev_embed> watchers for more info.	196	See the description of C<ev_embed> watchers for more info.
167		197
168	=item ev_set_allocator (void *(*cb)(void *ptr, size_t size))	198	=item ev_set_allocator (void *(*cb)(void *ptr, long size))
169		199
170	Sets the allocation function to use (the prototype and semantics are	200	Sets the allocation function to use (the prototype is similar - the
171	identical to the realloc C function). It is used to allocate and free	201	semantics are identical to the C<realloc> C89/SuS/POSIX function). It is
172	memory (no surprises here). If it returns zero when memory needs to be	202	used to allocate and free memory (no surprises here). If it returns zero
173	allocated, the library might abort or take some potentially destructive	203	when memory needs to be allocated (C<size != 0>), the library might abort
174	action. The default is your system realloc function.	204	or take some potentially destructive action.
		205
		206	Since some systems (at least OpenBSD and Darwin) fail to implement
		207	correct C<realloc> semantics, libev will use a wrapper around the system
		208	C<realloc> and C<free> functions by default.
175		209
176	You could override this function in high-availability programs to, say,	210	You could override this function in high-availability programs to, say,
177	free some memory if it cannot allocate memory, to use a special allocator,	211	free some memory if it cannot allocate memory, to use a special allocator,
178	or even to sleep a while and retry until some memory is available.	212	or even to sleep a while and retry until some memory is available.
179		213
180	Example: Replace the libev allocator with one that waits a bit and then	214	Example: Replace the libev allocator with one that waits a bit and then
181	retries).	215	retries (example requires a standards-compliant C<realloc>).
182		216
183	static void *	217	static void *
184	persistent_realloc (void *ptr, size_t size)	218	persistent_realloc (void *ptr, size_t size)
185	{	219	{
186	for (;;)	220	for (;;)
…		…
225		259
226	An event loop is described by a C<struct ev_loop *>. The library knows two	260	An event loop is described by a C<struct ev_loop *>. The library knows two
227	types of such loops, the I<default> loop, which supports signals and child	261	types of such loops, the I<default> loop, which supports signals and child
228	events, and dynamically created loops which do not.	262	events, and dynamically created loops which do not.
229		263
230	If you use threads, a common model is to run the default event loop
231	in your main thread (or in a separate thread) and for each thread you
232	create, you also create another event loop. Libev itself does no locking
233	whatsoever, so if you mix calls to the same event loop in different
234	threads, make sure you lock (this is usually a bad idea, though, even if
235	done correctly, because it's hideous and inefficient).
236
237	=over 4	264	=over 4
238		265
239	=item struct ev_loop *ev_default_loop (unsigned int flags)	266	=item struct ev_loop *ev_default_loop (unsigned int flags)
240		267
241	This will initialise the default event loop if it hasn't been initialised	268	This will initialise the default event loop if it hasn't been initialised
…		…
243	false. If it already was initialised it simply returns it (and ignores the	270	false. If it already was initialised it simply returns it (and ignores the
244	flags. If that is troubling you, check C<ev_backend ()> afterwards).	271	flags. If that is troubling you, check C<ev_backend ()> afterwards).
245		272
246	If you don't know what event loop to use, use the one returned from this	273	If you don't know what event loop to use, use the one returned from this
247	function.	274	function.
		275
		276	Note that this function is I<not> thread-safe, so if you want to use it
		277	from multiple threads, you have to lock (note also that this is unlikely,
		278	as loops cannot bes hared easily between threads anyway).
		279
		280	The default loop is the only loop that can handle C<ev_signal> and
		281	C<ev_child> watchers, and to do this, it always registers a handler
		282	for C<SIGCHLD>. If this is a problem for your app you can either
		283	create a dynamic loop with C<ev_loop_new> that doesn't do that, or you
		284	can simply overwrite the C<SIGCHLD> signal handler I<after> calling
		285	C<ev_default_init>.
248		286
249	The flags argument can be used to specify special behaviour or specific	287	The flags argument can be used to specify special behaviour or specific
250	backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>).	288	backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>).
251		289
252	The following flags are supported:	290	The following flags are supported:
…		…
265	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	303	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
266	override the flags completely if it is found in the environment. This is	304	override the flags completely if it is found in the environment. This is
267	useful to try out specific backends to test their performance, or to work	305	useful to try out specific backends to test their performance, or to work
268	around bugs.	306	around bugs.
269		307
		308	=item C<EVFLAG_FORKCHECK>
		309
		310	Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after
		311	a fork, you can also make libev check for a fork in each iteration by
		312	enabling this flag.
		313
		314	This works by calling C<getpid ()> on every iteration of the loop,
		315	and thus this might slow down your event loop if you do a lot of loop
		316	iterations and little real work, but is usually not noticeable (on my
		317	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence
		318	without a syscall and thus I<very> fast, but my GNU/Linux system also has
		319	C<pthread_atfork> which is even faster).
		320
		321	The big advantage of this flag is that you can forget about fork (and
		322	forget about forgetting to tell libev about forking) when you use this
		323	flag.
		324
		325	This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS>
		326	environment variable.
		327
270	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	328	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
271		329
272	This is your standard select(2) backend. Not I<completely> standard, as	330	This is your standard select(2) backend. Not I<completely> standard, as
273	libev tries to roll its own fd_set with no limits on the number of fds,	331	libev tries to roll its own fd_set with no limits on the number of fds,
274	but if that fails, expect a fairly low limit on the number of fds when	332	but if that fails, expect a fairly low limit on the number of fds when
275	using this backend. It doesn't scale too well (O(highest_fd)), but its usually	333	using this backend. It doesn't scale too well (O(highest_fd)), but its
276	the fastest backend for a low number of fds.	334	usually the fastest backend for a low number of (low-numbered :) fds.
		335
		336	To get good performance out of this backend you need a high amount of
		337	parallelity (most of the file descriptors should be busy). If you are
		338	writing a server, you should C<accept ()> in a loop to accept as many
		339	connections as possible during one iteration. You might also want to have
		340	a look at C<ev_set_io_collect_interval ()> to increase the amount of
		341	readyness notifications you get per iteration.
277		342
278	=item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows)	343	=item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows)
279		344
280	And this is your standard poll(2) backend. It's more complicated than	345	And this is your standard poll(2) backend. It's more complicated
281	select, but handles sparse fds better and has no artificial limit on the	346	than select, but handles sparse fds better and has no artificial
282	number of fds you can use (except it will slow down considerably with a	347	limit on the number of fds you can use (except it will slow down
283	lot of inactive fds). It scales similarly to select, i.e. O(total_fds).	348	considerably with a lot of inactive fds). It scales similarly to select,
		349	i.e. O(total_fds). See the entry for C<EVBACKEND_SELECT>, above, for
		350	performance tips.
284		351
285	=item C<EVBACKEND_EPOLL> (value 4, Linux)	352	=item C<EVBACKEND_EPOLL> (value 4, Linux)
286		353
287	For few fds, this backend is a bit little slower than poll and select,	354	For few fds, this backend is a bit little slower than poll and select,
288	but it scales phenomenally better. While poll and select usually scale like	355	but it scales phenomenally better. While poll and select usually scale
289	O(total_fds) where n is the total number of fds (or the highest fd), epoll scales	356	like O(total_fds) where n is the total number of fds (or the highest fd),
290	either O(1) or O(active_fds).	357	epoll scales either O(1) or O(active_fds). The epoll design has a number
		358	of shortcomings, such as silently dropping events in some hard-to-detect
		359	cases and requiring a syscall per fd change, no fork support and bad
		360	support for dup.
291		361
292	While stopping and starting an I/O watcher in the same iteration will	362	While stopping, setting and starting an I/O watcher in the same iteration
293	result in some caching, there is still a syscall per such incident	363	will result in some caching, there is still a syscall per such incident
294	(because the fd could point to a different file description now), so its	364	(because the fd could point to a different file description now), so its
295	best to avoid that. Also, dup()ed file descriptors might not work very	365	best to avoid that. Also, C<dup ()>'ed file descriptors might not work
296	well if you register events for both fds.	366	very well if you register events for both fds.
297		367
298	Please note that epoll sometimes generates spurious notifications, so you	368	Please note that epoll sometimes generates spurious notifications, so you
299	need to use non-blocking I/O or other means to avoid blocking when no data	369	need to use non-blocking I/O or other means to avoid blocking when no data
300	(or space) is available.	370	(or space) is available.
301		371
		372	Best performance from this backend is achieved by not unregistering all
		373	watchers for a file descriptor until it has been closed, if possible, i.e.
		374	keep at least one watcher active per fd at all times.
		375
		376	While nominally embeddeble in other event loops, this feature is broken in
		377	all kernel versions tested so far.
		378
302	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)	379	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)
303		380
304	Kqueue deserves special mention, as at the time of this writing, it	381	Kqueue deserves special mention, as at the time of this writing, it
305	was broken on all BSDs except NetBSD (usually it doesn't work with	382	was broken on all BSDs except NetBSD (usually it doesn't work reliably
306	anything but sockets and pipes, except on Darwin, where of course its	383	with anything but sockets and pipes, except on Darwin, where of course
307	completely useless). For this reason its not being "autodetected"	384	it's completely useless). For this reason it's not being "autodetected"
308	unless you explicitly specify it explicitly in the flags (i.e. using	385	unless you explicitly specify it explicitly in the flags (i.e. using
309	C<EVBACKEND_KQUEUE>).	386	C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough)
		387	system like NetBSD.
		388
		389	You still can embed kqueue into a normal poll or select backend and use it
		390	only for sockets (after having made sure that sockets work with kqueue on
		391	the target platform). See C<ev_embed> watchers for more info.
310		392
311	It scales in the same way as the epoll backend, but the interface to the	393	It scales in the same way as the epoll backend, but the interface to the
312	kernel is more efficient (which says nothing about its actual speed, of	394	kernel is more efficient (which says nothing about its actual speed, of
313	course). While starting and stopping an I/O watcher does not cause an	395	course). While stopping, setting and starting an I/O watcher does never
314	extra syscall as with epoll, it still adds up to four event changes per	396	cause an extra syscall as with C<EVBACKEND_EPOLL>, it still adds up to
315	incident, so its best to avoid that.	397	two event changes per incident, support for C<fork ()> is very bad and it
		398	drops fds silently in similarly hard-to-detect cases.
		399
		400	This backend usually performs well under most conditions.
		401
		402	While nominally embeddable in other event loops, this doesn't work
		403	everywhere, so you might need to test for this. And since it is broken
		404	almost everywhere, you should only use it when you have a lot of sockets
		405	(for which it usually works), by embedding it into another event loop
		406	(e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>) and using it only for
		407	sockets.
316		408
317	=item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8)	409	=item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8)
318		410
319	This is not implemented yet (and might never be).	411	This is not implemented yet (and might never be, unless you send me an
		412	implementation). According to reports, C</dev/poll> only supports sockets
		413	and is not embeddable, which would limit the usefulness of this backend
		414	immensely.
320		415
321	=item C<EVBACKEND_PORT> (value 32, Solaris 10)	416	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
322		417
323	This uses the Solaris 10 port mechanism. As with everything on Solaris,	418	This uses the Solaris 10 event port mechanism. As with everything on Solaris,
324	it's really slow, but it still scales very well (O(active_fds)).	419	it's really slow, but it still scales very well (O(active_fds)).
325		420
326	Please note that solaris ports can result in a lot of spurious	421	Please note that solaris event ports can deliver a lot of spurious
327	notifications, so you need to use non-blocking I/O or other means to avoid	422	notifications, so you need to use non-blocking I/O or other means to avoid
328	blocking when no data (or space) is available.	423	blocking when no data (or space) is available.
		424
		425	While this backend scales well, it requires one system call per active
		426	file descriptor per loop iteration. For small and medium numbers of file
		427	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend
		428	might perform better.
		429
		430	On the positive side, ignoring the spurious readyness notifications, this
		431	backend actually performed to specification in all tests and is fully
		432	embeddable, which is a rare feat among the OS-specific backends.
329		433
330	=item C<EVBACKEND_ALL>	434	=item C<EVBACKEND_ALL>
331		435
332	Try all backends (even potentially broken ones that wouldn't be tried	436	Try all backends (even potentially broken ones that wouldn't be tried
333	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as	437	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as
334	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.	438	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.
335		439
		440	It is definitely not recommended to use this flag.
		441
336	=back	442	=back
337		443
338	If one or more of these are ored into the flags value, then only these	444	If one or more of these are ored into the flags value, then only these
339	backends will be tried (in the reverse order as given here). If none are	445	backends will be tried (in the reverse order as listed here). If none are
340	specified, most compiled-in backend will be tried, usually in reverse	446	specified, all backends in C<ev_recommended_backends ()> will be tried.
341	order of their flag values :)
342		447
343	The most typical usage is like this:	448	The most typical usage is like this:
344		449
345	if (!ev_default_loop (0))	450	if (!ev_default_loop (0))
346	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");	451	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
…		…
360		465
361	Similar to C<ev_default_loop>, but always creates a new event loop that is	466	Similar to C<ev_default_loop>, but always creates a new event loop that is
362	always distinct from the default loop. Unlike the default loop, it cannot	467	always distinct from the default loop. Unlike the default loop, it cannot
363	handle signal and child watchers, and attempts to do so will be greeted by	468	handle signal and child watchers, and attempts to do so will be greeted by
364	undefined behaviour (or a failed assertion if assertions are enabled).	469	undefined behaviour (or a failed assertion if assertions are enabled).
		470
		471	Note that this function I<is> thread-safe, and the recommended way to use
		472	libev with threads is indeed to create one loop per thread, and using the
		473	default loop in the "main" or "initial" thread.
365		474
366	Example: Try to create a event loop that uses epoll and nothing else.	475	Example: Try to create a event loop that uses epoll and nothing else.
367		476
368	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	477	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
369	if (!epoller)	478	if (!epoller)
…		…
374	Destroys the default loop again (frees all memory and kernel state	483	Destroys the default loop again (frees all memory and kernel state
375	etc.). None of the active event watchers will be stopped in the normal	484	etc.). None of the active event watchers will be stopped in the normal
376	sense, so e.g. C<ev_is_active> might still return true. It is your	485	sense, so e.g. C<ev_is_active> might still return true. It is your
377	responsibility to either stop all watchers cleanly yoursef I<before>	486	responsibility to either stop all watchers cleanly yoursef I<before>
378	calling this function, or cope with the fact afterwards (which is usually	487	calling this function, or cope with the fact afterwards (which is usually
379	the easiest thing, youc na just ignore the watchers and/or C<free ()> them	488	the easiest thing, you can just ignore the watchers and/or C<free ()> them
380	for example).	489	for example).
		490
		491	Note that certain global state, such as signal state, will not be freed by
		492	this function, and related watchers (such as signal and child watchers)
		493	would need to be stopped manually.
		494
		495	In general it is not advisable to call this function except in the
		496	rare occasion where you really need to free e.g. the signal handling
		497	pipe fds. If you need dynamically allocated loops it is better to use
		498	C<ev_loop_new> and C<ev_loop_destroy>).
381		499
382	=item ev_loop_destroy (loop)	500	=item ev_loop_destroy (loop)
383		501
384	Like C<ev_default_destroy>, but destroys an event loop created by an	502	Like C<ev_default_destroy>, but destroys an event loop created by an
385	earlier call to C<ev_loop_new>.	503	earlier call to C<ev_loop_new>.
386		504
387	=item ev_default_fork ()	505	=item ev_default_fork ()
388		506
		507	This function sets a flag that causes subsequent C<ev_loop> iterations
389	This function reinitialises the kernel state for backends that have	508	to reinitialise the kernel state for backends that have one. Despite the
390	one. Despite the name, you can call it anytime, but it makes most sense	509	name, you can call it anytime, but it makes most sense after forking, in
391	after forking, in either the parent or child process (or both, but that	510	the child process (or both child and parent, but that again makes little
392	again makes little sense).	511	sense). You I<must> call it in the child before using any of the libev
		512	functions, and it will only take effect at the next C<ev_loop> iteration.
393		513
394	You I<must> call this function in the child process after forking if and	514	On the other hand, you only need to call this function in the child
395	only if you want to use the event library in both processes. If you just	515	process if and only if you want to use the event library in the child. If
396	fork+exec, you don't have to call it.	516	you just fork+exec, you don't have to call it at all.
397		517
398	The function itself is quite fast and it's usually not a problem to call	518	The function itself is quite fast and it's usually not a problem to call
399	it just in case after a fork. To make this easy, the function will fit in	519	it just in case after a fork. To make this easy, the function will fit in
400	quite nicely into a call to C<pthread_atfork>:	520	quite nicely into a call to C<pthread_atfork>:
401		521
402	pthread_atfork (0, 0, ev_default_fork);	522	pthread_atfork (0, 0, ev_default_fork);
403		523
404	At the moment, C<EVBACKEND_SELECT> and C<EVBACKEND_POLL> are safe to use
405	without calling this function, so if you force one of those backends you
406	do not need to care.
407
408	=item ev_loop_fork (loop)	524	=item ev_loop_fork (loop)
409		525
410	Like C<ev_default_fork>, but acts on an event loop created by	526	Like C<ev_default_fork>, but acts on an event loop created by
411	C<ev_loop_new>. Yes, you have to call this on every allocated event loop	527	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
412	after fork, and how you do this is entirely your own problem.	528	after fork, and how you do this is entirely your own problem.
		529
		530	=item int ev_is_default_loop (loop)
		531
		532	Returns true when the given loop actually is the default loop, false otherwise.
		533
		534	=item unsigned int ev_loop_count (loop)
		535
		536	Returns the count of loop iterations for the loop, which is identical to
		537	the number of times libev did poll for new events. It starts at C<0> and
		538	happily wraps around with enough iterations.
		539
		540	This value can sometimes be useful as a generation counter of sorts (it
		541	"ticks" the number of loop iterations), as it roughly corresponds with
		542	C<ev_prepare> and C<ev_check> calls.
413		543
414	=item unsigned int ev_backend (loop)	544	=item unsigned int ev_backend (loop)
415		545
416	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	546	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
417	use.	547	use.
…		…
420		550
421	Returns the current "event loop time", which is the time the event loop	551	Returns the current "event loop time", which is the time the event loop
422	received events and started processing them. This timestamp does not	552	received events and started processing them. This timestamp does not
423	change as long as callbacks are being processed, and this is also the base	553	change as long as callbacks are being processed, and this is also the base
424	time used for relative timers. You can treat it as the timestamp of the	554	time used for relative timers. You can treat it as the timestamp of the
425	event occuring (or more correctly, libev finding out about it).	555	event occurring (or more correctly, libev finding out about it).
426		556
427	=item ev_loop (loop, int flags)	557	=item ev_loop (loop, int flags)
428		558
429	Finally, this is it, the event handler. This function usually is called	559	Finally, this is it, the event handler. This function usually is called
430	after you initialised all your watchers and you want to start handling	560	after you initialised all your watchers and you want to start handling
…		…
451	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is	581	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is
452	usually a better approach for this kind of thing.	582	usually a better approach for this kind of thing.
453		583
454	Here are the gory details of what C<ev_loop> does:	584	Here are the gory details of what C<ev_loop> does:
455		585
456	* If there are no active watchers (reference count is zero), return.	586	- Before the first iteration, call any pending watchers.
457	- Queue prepare watchers and then call all outstanding watchers.	587	* If EVFLAG_FORKCHECK was used, check for a fork.
		588	- If a fork was detected, queue and call all fork watchers.
		589	- Queue and call all prepare watchers.
458	- If we have been forked, recreate the kernel state.	590	- If we have been forked, recreate the kernel state.
459	- Update the kernel state with all outstanding changes.	591	- Update the kernel state with all outstanding changes.
460	- Update the "event loop time".	592	- Update the "event loop time".
461	- Calculate for how long to block.	593	- Calculate for how long to sleep or block, if at all
		594	(active idle watchers, EVLOOP_NONBLOCK or not having
		595	any active watchers at all will result in not sleeping).
		596	- Sleep if the I/O and timer collect interval say so.
462	- Block the process, waiting for any events.	597	- Block the process, waiting for any events.
463	- Queue all outstanding I/O (fd) events.	598	- Queue all outstanding I/O (fd) events.
464	- Update the "event loop time" and do time jump handling.	599	- Update the "event loop time" and do time jump handling.
465	- Queue all outstanding timers.	600	- Queue all outstanding timers.
466	- Queue all outstanding periodics.	601	- Queue all outstanding periodics.
467	- If no events are pending now, queue all idle watchers.	602	- If no events are pending now, queue all idle watchers.
468	- Queue all check watchers.	603	- Queue all check watchers.
469	- Call all queued watchers in reverse order (i.e. check watchers first).	604	- Call all queued watchers in reverse order (i.e. check watchers first).
470	Signals and child watchers are implemented as I/O watchers, and will	605	Signals and child watchers are implemented as I/O watchers, and will
471	be handled here by queueing them when their watcher gets executed.	606	be handled here by queueing them when their watcher gets executed.
472	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	607	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
473	were used, return, otherwise continue with step *.	608	were used, or there are no active watchers, return, otherwise
		609	continue with step *.
474		610
475	Example: Queue some jobs and then loop until no events are outsanding	611	Example: Queue some jobs and then loop until no events are outstanding
476	anymore.	612	anymore.
477		613
478	... queue jobs here, make sure they register event watchers as long	614	... queue jobs here, make sure they register event watchers as long
479	... as they still have work to do (even an idle watcher will do..)	615	... as they still have work to do (even an idle watcher will do..)
480	ev_loop (my_loop, 0);	616	ev_loop (my_loop, 0);
…		…
484		620
485	Can be used to make a call to C<ev_loop> return early (but only after it	621	Can be used to make a call to C<ev_loop> return early (but only after it
486	has processed all outstanding events). The C<how> argument must be either	622	has processed all outstanding events). The C<how> argument must be either
487	C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or	623	C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or
488	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.	624	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.
		625
		626	This "unloop state" will be cleared when entering C<ev_loop> again.
489		627
490	=item ev_ref (loop)	628	=item ev_ref (loop)
491		629
492	=item ev_unref (loop)	630	=item ev_unref (loop)
493		631
…		…
498	returning, ev_unref() after starting, and ev_ref() before stopping it. For	636	returning, ev_unref() after starting, and ev_ref() before stopping it. For
499	example, libev itself uses this for its internal signal pipe: It is not	637	example, libev itself uses this for its internal signal pipe: It is not
500	visible to the libev user and should not keep C<ev_loop> from exiting if	638	visible to the libev user and should not keep C<ev_loop> from exiting if
501	no event watchers registered by it are active. It is also an excellent	639	no event watchers registered by it are active. It is also an excellent
502	way to do this for generic recurring timers or from within third-party	640	way to do this for generic recurring timers or from within third-party
503	libraries. Just remember to I<unref after start> and I<ref before stop>.	641	libraries. Just remember to I<unref after start> and I<ref before stop>
		642	(but only if the watcher wasn't active before, or was active before,
		643	respectively).
504		644
505	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	645	Example: Create a signal watcher, but keep it from keeping C<ev_loop>
506	running when nothing else is active.	646	running when nothing else is active.
507		647
508	struct ev_signal exitsig;	648	struct ev_signal exitsig;
…		…
512		652
513	Example: For some weird reason, unregister the above signal handler again.	653	Example: For some weird reason, unregister the above signal handler again.
514		654
515	ev_ref (loop);	655	ev_ref (loop);
516	ev_signal_stop (loop, &exitsig);	656	ev_signal_stop (loop, &exitsig);
		657
		658	=item ev_set_io_collect_interval (loop, ev_tstamp interval)
		659
		660	=item ev_set_timeout_collect_interval (loop, ev_tstamp interval)
		661
		662	These advanced functions influence the time that libev will spend waiting
		663	for events. Both are by default C<0>, meaning that libev will try to
		664	invoke timer/periodic callbacks and I/O callbacks with minimum latency.
		665
		666	Setting these to a higher value (the C<interval> I<must> be >= C<0>)
		667	allows libev to delay invocation of I/O and timer/periodic callbacks to
		668	increase efficiency of loop iterations.
		669
		670	The background is that sometimes your program runs just fast enough to
		671	handle one (or very few) event(s) per loop iteration. While this makes
		672	the program responsive, it also wastes a lot of CPU time to poll for new
		673	events, especially with backends like C<select ()> which have a high
		674	overhead for the actual polling but can deliver many events at once.
		675
		676	By setting a higher I<io collect interval> you allow libev to spend more
		677	time collecting I/O events, so you can handle more events per iteration,
		678	at the cost of increasing latency. Timeouts (both C<ev_periodic> and
		679	C<ev_timer>) will be not affected. Setting this to a non-null value will
		680	introduce an additional C<ev_sleep ()> call into most loop iterations.
		681
		682	Likewise, by setting a higher I<timeout collect interval> you allow libev
		683	to spend more time collecting timeouts, at the expense of increased
		684	latency (the watcher callback will be called later). C<ev_io> watchers
		685	will not be affected. Setting this to a non-null value will not introduce
		686	any overhead in libev.
		687
		688	Many (busy) programs can usually benefit by setting the io collect
		689	interval to a value near C<0.1> or so, which is often enough for
		690	interactive servers (of course not for games), likewise for timeouts. It
		691	usually doesn't make much sense to set it to a lower value than C<0.01>,
		692	as this approsaches the timing granularity of most systems.
517		693
518	=back	694	=back
519		695
520		696
521	=head1 ANATOMY OF A WATCHER	697	=head1 ANATOMY OF A WATCHER
…		…
621	=item C<EV_FORK>	797	=item C<EV_FORK>
622		798
623	The event loop has been resumed in the child process after fork (see	799	The event loop has been resumed in the child process after fork (see
624	C<ev_fork>).	800	C<ev_fork>).
625		801
		802	=item C<EV_ASYNC>
		803
		804	The given async watcher has been asynchronously notified (see C<ev_async>).
		805
626	=item C<EV_ERROR>	806	=item C<EV_ERROR>
627		807
628	An unspecified error has occured, the watcher has been stopped. This might	808	An unspecified error has occured, the watcher has been stopped. This might
629	happen because the watcher could not be properly started because libev	809	happen because the watcher could not be properly started because libev
630	ran out of memory, a file descriptor was found to be closed or any other	810	ran out of memory, a file descriptor was found to be closed or any other
…		…
701	=item bool ev_is_pending (ev_TYPE *watcher)	881	=item bool ev_is_pending (ev_TYPE *watcher)
702		882
703	Returns a true value iff the watcher is pending, (i.e. it has outstanding	883	Returns a true value iff the watcher is pending, (i.e. it has outstanding
704	events but its callback has not yet been invoked). As long as a watcher	884	events but its callback has not yet been invoked). As long as a watcher
705	is pending (but not active) you must not call an init function on it (but	885	is pending (but not active) you must not call an init function on it (but
706	C<ev_TYPE_set> is safe) and you must make sure the watcher is available to	886	C<ev_TYPE_set> is safe), you must not change its priority, and you must
707	libev (e.g. you cnanot C<free ()> it).	887	make sure the watcher is available to libev (e.g. you cannot C<free ()>
		888	it).
708		889
709	=item callback ev_cb (ev_TYPE *watcher)	890	=item callback ev_cb (ev_TYPE *watcher)
710		891
711	Returns the callback currently set on the watcher.	892	Returns the callback currently set on the watcher.
712		893
713	=item ev_cb_set (ev_TYPE *watcher, callback)	894	=item ev_cb_set (ev_TYPE *watcher, callback)
714		895
715	Change the callback. You can change the callback at virtually any time	896	Change the callback. You can change the callback at virtually any time
716	(modulo threads).	897	(modulo threads).
		898
		899	=item ev_set_priority (ev_TYPE *watcher, priority)
		900
		901	=item int ev_priority (ev_TYPE *watcher)
		902
		903	Set and query the priority of the watcher. The priority is a small
		904	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>
		905	(default: C<-2>). Pending watchers with higher priority will be invoked
		906	before watchers with lower priority, but priority will not keep watchers
		907	from being executed (except for C<ev_idle> watchers).
		908
		909	This means that priorities are I<only> used for ordering callback
		910	invocation after new events have been received. This is useful, for
		911	example, to reduce latency after idling, or more often, to bind two
		912	watchers on the same event and make sure one is called first.
		913
		914	If you need to suppress invocation when higher priority events are pending
		915	you need to look at C<ev_idle> watchers, which provide this functionality.
		916
		917	You I<must not> change the priority of a watcher as long as it is active or
		918	pending.
		919
		920	The default priority used by watchers when no priority has been set is
		921	always C<0>, which is supposed to not be too high and not be too low :).
		922
		923	Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is
		924	fine, as long as you do not mind that the priority value you query might
		925	or might not have been adjusted to be within valid range.
		926
		927	=item ev_invoke (loop, ev_TYPE *watcher, int revents)
		928
		929	Invoke the C<watcher> with the given C<loop> and C<revents>. Neither
		930	C<loop> nor C<revents> need to be valid as long as the watcher callback
		931	can deal with that fact.
		932
		933	=item int ev_clear_pending (loop, ev_TYPE *watcher)
		934
		935	If the watcher is pending, this function returns clears its pending status
		936	and returns its C<revents> bitset (as if its callback was invoked). If the
		937	watcher isn't pending it does nothing and returns C<0>.
717		938
718	=back	939	=back
719		940
720		941
721	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	942	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
806	In general you can register as many read and/or write event watchers per	1027	In general you can register as many read and/or write event watchers per
807	fd as you want (as long as you don't confuse yourself). Setting all file	1028	fd as you want (as long as you don't confuse yourself). Setting all file
808	descriptors to non-blocking mode is also usually a good idea (but not	1029	descriptors to non-blocking mode is also usually a good idea (but not
809	required if you know what you are doing).	1030	required if you know what you are doing).
810		1031
811	You have to be careful with dup'ed file descriptors, though. Some backends
812	(the linux epoll backend is a notable example) cannot handle dup'ed file
813	descriptors correctly if you register interest in two or more fds pointing
814	to the same underlying file/socket/etc. description (that is, they share
815	the same underlying "file open").
816
817	If you must do this, then force the use of a known-to-be-good backend	1032	If you must do this, then force the use of a known-to-be-good backend
818	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and	1033	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and
819	C<EVBACKEND_POLL>).	1034	C<EVBACKEND_POLL>).
820		1035
821	Another thing you have to watch out for is that it is quite easy to	1036	Another thing you have to watch out for is that it is quite easy to
…		…
827	it is best to always use non-blocking I/O: An extra C<read>(2) returning	1042	it is best to always use non-blocking I/O: An extra C<read>(2) returning
828	C<EAGAIN> is far preferable to a program hanging until some data arrives.	1043	C<EAGAIN> is far preferable to a program hanging until some data arrives.
829		1044
830	If you cannot run the fd in non-blocking mode (for example you should not	1045	If you cannot run the fd in non-blocking mode (for example you should not
831	play around with an Xlib connection), then you have to seperately re-test	1046	play around with an Xlib connection), then you have to seperately re-test
832	wether a file descriptor is really ready with a known-to-be good interface	1047	whether a file descriptor is really ready with a known-to-be good interface
833	such as poll (fortunately in our Xlib example, Xlib already does this on	1048	such as poll (fortunately in our Xlib example, Xlib already does this on
834	its own, so its quite safe to use).	1049	its own, so its quite safe to use).
		1050
		1051	=head3 The special problem of disappearing file descriptors
		1052
		1053	Some backends (e.g. kqueue, epoll) need to be told about closing a file
		1054	descriptor (either by calling C<close> explicitly or by any other means,
		1055	such as C<dup>). The reason is that you register interest in some file
		1056	descriptor, but when it goes away, the operating system will silently drop
		1057	this interest. If another file descriptor with the same number then is
		1058	registered with libev, there is no efficient way to see that this is, in
		1059	fact, a different file descriptor.
		1060
		1061	To avoid having to explicitly tell libev about such cases, libev follows
		1062	the following policy: Each time C<ev_io_set> is being called, libev
		1063	will assume that this is potentially a new file descriptor, otherwise
		1064	it is assumed that the file descriptor stays the same. That means that
		1065	you I<have> to call C<ev_io_set> (or C<ev_io_init>) when you change the
		1066	descriptor even if the file descriptor number itself did not change.
		1067
		1068	This is how one would do it normally anyway, the important point is that
		1069	the libev application should not optimise around libev but should leave
		1070	optimisations to libev.
		1071
		1072	=head3 The special problem of dup'ed file descriptors
		1073
		1074	Some backends (e.g. epoll), cannot register events for file descriptors,
		1075	but only events for the underlying file descriptions. That means when you
		1076	have C<dup ()>'ed file descriptors or weirder constellations, and register
		1077	events for them, only one file descriptor might actually receive events.
		1078
		1079	There is no workaround possible except not registering events
		1080	for potentially C<dup ()>'ed file descriptors, or to resort to
		1081	C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>.
		1082
		1083	=head3 The special problem of fork
		1084
		1085	Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit
		1086	useless behaviour. Libev fully supports fork, but needs to be told about
		1087	it in the child.
		1088
		1089	To support fork in your programs, you either have to call
		1090	C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child,
		1091	enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or
		1092	C<EVBACKEND_POLL>.
		1093
		1094	=head3 The special problem of SIGPIPE
		1095
		1096	While not really specific to libev, it is easy to forget about SIGPIPE:
		1097	when reading from a pipe whose other end has been closed, your program
		1098	gets send a SIGPIPE, which, by default, aborts your program. For most
		1099	programs this is sensible behaviour, for daemons, this is usually
		1100	undesirable.
		1101
		1102	So when you encounter spurious, unexplained daemon exits, make sure you
		1103	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon
		1104	somewhere, as that would have given you a big clue).
		1105
		1106
		1107	=head3 Watcher-Specific Functions
835		1108
836	=over 4	1109	=over 4
837		1110
838	=item ev_io_init (ev_io *, callback, int fd, int events)	1111	=item ev_io_init (ev_io *, callback, int fd, int events)
839		1112
…		…
850	=item int events [read-only]	1123	=item int events [read-only]
851		1124
852	The events being watched.	1125	The events being watched.
853		1126
854	=back	1127	=back
		1128
		1129	=head3 Examples
855		1130
856	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well	1131	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well
857	readable, but only once. Since it is likely line-buffered, you could	1132	readable, but only once. Since it is likely line-buffered, you could
858	attempt to read a whole line in the callback.	1133	attempt to read a whole line in the callback.
859		1134
…		…
893		1168
894	The callback is guarenteed to be invoked only when its timeout has passed,	1169	The callback is guarenteed to be invoked only when its timeout has passed,
895	but if multiple timers become ready during the same loop iteration then	1170	but if multiple timers become ready during the same loop iteration then
896	order of execution is undefined.	1171	order of execution is undefined.
897		1172
		1173	=head3 Watcher-Specific Functions and Data Members
		1174
898	=over 4	1175	=over 4
899		1176
900	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	1177	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
901		1178
902	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)	1179	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)
…		…
910	configure a timer to trigger every 10 seconds, then it will trigger at	1187	configure a timer to trigger every 10 seconds, then it will trigger at
911	exactly 10 second intervals. If, however, your program cannot keep up with	1188	exactly 10 second intervals. If, however, your program cannot keep up with
912	the timer (because it takes longer than those 10 seconds to do stuff) the	1189	the timer (because it takes longer than those 10 seconds to do stuff) the
913	timer will not fire more than once per event loop iteration.	1190	timer will not fire more than once per event loop iteration.
914		1191
915	=item ev_timer_again (loop)	1192	=item ev_timer_again (loop, ev_timer *)
916		1193
917	This will act as if the timer timed out and restart it again if it is	1194	This will act as if the timer timed out and restart it again if it is
918	repeating. The exact semantics are:	1195	repeating. The exact semantics are:
919		1196
		1197	If the timer is pending, its pending status is cleared.
		1198
920	If the timer is started but nonrepeating, stop it.	1199	If the timer is started but nonrepeating, stop it (as if it timed out).
921		1200
922	If the timer is repeating, either start it if necessary (with the repeat	1201	If the timer is repeating, either start it if necessary (with the
923	value), or reset the running timer to the repeat value.	1202	C<repeat> value), or reset the running timer to the C<repeat> value.
924		1203
925	This sounds a bit complicated, but here is a useful and typical	1204	This sounds a bit complicated, but here is a useful and typical
926	example: Imagine you have a tcp connection and you want a so-called	1205	example: Imagine you have a tcp connection and you want a so-called idle
927	idle timeout, that is, you want to be called when there have been,	1206	timeout, that is, you want to be called when there have been, say, 60
928	say, 60 seconds of inactivity on the socket. The easiest way to do	1207	seconds of inactivity on the socket. The easiest way to do this is to
929	this is to configure an C<ev_timer> with C<after>=C<repeat>=C<60> and calling	1208	configure an C<ev_timer> with a C<repeat> value of C<60> and then call
930	C<ev_timer_again> each time you successfully read or write some data. If	1209	C<ev_timer_again> each time you successfully read or write some data. If
931	you go into an idle state where you do not expect data to travel on the	1210	you go into an idle state where you do not expect data to travel on the
932	socket, you can stop the timer, and again will automatically restart it if	1211	socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will
933	need be.	1212	automatically restart it if need be.
934		1213
935	You can also ignore the C<after> value and C<ev_timer_start> altogether	1214	That means you can ignore the C<after> value and C<ev_timer_start>
936	and only ever use the C<repeat> value:	1215	altogether and only ever use the C<repeat> value and C<ev_timer_again>:
937		1216
938	ev_timer_init (timer, callback, 0., 5.);	1217	ev_timer_init (timer, callback, 0., 5.);
939	ev_timer_again (loop, timer);	1218	ev_timer_again (loop, timer);
940	...	1219	...
941	timer->again = 17.;	1220	timer->again = 17.;
942	ev_timer_again (loop, timer);	1221	ev_timer_again (loop, timer);
943	...	1222	...
944	timer->again = 10.;	1223	timer->again = 10.;
945	ev_timer_again (loop, timer);	1224	ev_timer_again (loop, timer);
946		1225
947	This is more efficient then stopping/starting the timer eahc time you want	1226	This is more slightly efficient then stopping/starting the timer each time
948	to modify its timeout value.	1227	you want to modify its timeout value.
949		1228
950	=item ev_tstamp repeat [read-write]	1229	=item ev_tstamp repeat [read-write]
951		1230
952	The current C<repeat> value. Will be used each time the watcher times out	1231	The current C<repeat> value. Will be used each time the watcher times out
953	or C<ev_timer_again> is called and determines the next timeout (if any),	1232	or C<ev_timer_again> is called and determines the next timeout (if any),
954	which is also when any modifications are taken into account.	1233	which is also when any modifications are taken into account.
955		1234
956	=back	1235	=back
		1236
		1237	=head3 Examples
957		1238
958	Example: Create a timer that fires after 60 seconds.	1239	Example: Create a timer that fires after 60 seconds.
959		1240
960	static void	1241	static void
961	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1242	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
…		…
995	but on wallclock time (absolute time). You can tell a periodic watcher	1276	but on wallclock time (absolute time). You can tell a periodic watcher
996	to trigger "at" some specific point in time. For example, if you tell a	1277	to trigger "at" some specific point in time. For example, if you tell a
997	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()	1278	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()
998	+ 10.>) and then reset your system clock to the last year, then it will	1279	+ 10.>) and then reset your system clock to the last year, then it will
999	take a year to trigger the event (unlike an C<ev_timer>, which would trigger	1280	take a year to trigger the event (unlike an C<ev_timer>, which would trigger
1000	roughly 10 seconds later and of course not if you reset your system time	1281	roughly 10 seconds later).
1001	again).
1002		1282
1003	They can also be used to implement vastly more complex timers, such as	1283	They can also be used to implement vastly more complex timers, such as
1004	triggering an event on eahc midnight, local time.	1284	triggering an event on each midnight, local time or other, complicated,
		1285	rules.
1005		1286
1006	As with timers, the callback is guarenteed to be invoked only when the	1287	As with timers, the callback is guarenteed to be invoked only when the
1007	time (C<at>) has been passed, but if multiple periodic timers become ready	1288	time (C<at>) has been passed, but if multiple periodic timers become ready
1008	during the same loop iteration then order of execution is undefined.	1289	during the same loop iteration then order of execution is undefined.
1009		1290
		1291	=head3 Watcher-Specific Functions and Data Members
		1292
1010	=over 4	1293	=over 4
1011		1294
1012	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)	1295	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)
1013		1296
1014	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)	1297	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)
…		…
1016	Lots of arguments, lets sort it out... There are basically three modes of	1299	Lots of arguments, lets sort it out... There are basically three modes of
1017	operation, and we will explain them from simplest to complex:	1300	operation, and we will explain them from simplest to complex:
1018		1301
1019	=over 4	1302	=over 4
1020		1303
1021	=item * absolute timer (interval = reschedule_cb = 0)	1304	=item * absolute timer (at = time, interval = reschedule_cb = 0)
1022		1305
1023	In this configuration the watcher triggers an event at the wallclock time	1306	In this configuration the watcher triggers an event at the wallclock time
1024	C<at> and doesn't repeat. It will not adjust when a time jump occurs,	1307	C<at> and doesn't repeat. It will not adjust when a time jump occurs,
1025	that is, if it is to be run at January 1st 2011 then it will run when the	1308	that is, if it is to be run at January 1st 2011 then it will run when the
1026	system time reaches or surpasses this time.	1309	system time reaches or surpasses this time.
1027		1310
1028	=item * non-repeating interval timer (interval > 0, reschedule_cb = 0)	1311	=item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
1029		1312
1030	In this mode the watcher will always be scheduled to time out at the next	1313	In this mode the watcher will always be scheduled to time out at the next
1031	C<at + N * interval> time (for some integer N) and then repeat, regardless	1314	C<at + N * interval> time (for some integer N, which can also be negative)
1032	of any time jumps.	1315	and then repeat, regardless of any time jumps.
1033		1316
1034	This can be used to create timers that do not drift with respect to system	1317	This can be used to create timers that do not drift with respect to system
1035	time:	1318	time:
1036		1319
1037	ev_periodic_set (&periodic, 0., 3600., 0);	1320	ev_periodic_set (&periodic, 0., 3600., 0);
…		…
1043		1326
1044	Another way to think about it (for the mathematically inclined) is that	1327	Another way to think about it (for the mathematically inclined) is that
1045	C<ev_periodic> will try to run the callback in this mode at the next possible	1328	C<ev_periodic> will try to run the callback in this mode at the next possible
1046	time where C<time = at (mod interval)>, regardless of any time jumps.	1329	time where C<time = at (mod interval)>, regardless of any time jumps.
1047		1330
		1331	For numerical stability it is preferable that the C<at> value is near
		1332	C<ev_now ()> (the current time), but there is no range requirement for
		1333	this value.
		1334
1048	=item * manual reschedule mode (reschedule_cb = callback)	1335	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
1049		1336
1050	In this mode the values for C<interval> and C<at> are both being	1337	In this mode the values for C<interval> and C<at> are both being
1051	ignored. Instead, each time the periodic watcher gets scheduled, the	1338	ignored. Instead, each time the periodic watcher gets scheduled, the
1052	reschedule callback will be called with the watcher as first, and the	1339	reschedule callback will be called with the watcher as first, and the
1053	current time as second argument.	1340	current time as second argument.
1054		1341
1055	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,	1342	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,
1056	ever, or make any event loop modifications>. If you need to stop it,	1343	ever, or make any event loop modifications>. If you need to stop it,
1057	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by	1344	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by
1058	starting a prepare watcher).	1345	starting an C<ev_prepare> watcher, which is legal).
1059		1346
1060	Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w,	1347	Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w,
1061	ev_tstamp now)>, e.g.:	1348	ev_tstamp now)>, e.g.:
1062		1349
1063	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	1350	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
…		…
1086	Simply stops and restarts the periodic watcher again. This is only useful	1373	Simply stops and restarts the periodic watcher again. This is only useful
1087	when you changed some parameters or the reschedule callback would return	1374	when you changed some parameters or the reschedule callback would return
1088	a different time than the last time it was called (e.g. in a crond like	1375	a different time than the last time it was called (e.g. in a crond like
1089	program when the crontabs have changed).	1376	program when the crontabs have changed).
1090		1377
		1378	=item ev_tstamp offset [read-write]
		1379
		1380	When repeating, this contains the offset value, otherwise this is the
		1381	absolute point in time (the C<at> value passed to C<ev_periodic_set>).
		1382
		1383	Can be modified any time, but changes only take effect when the periodic
		1384	timer fires or C<ev_periodic_again> is being called.
		1385
1091	=item ev_tstamp interval [read-write]	1386	=item ev_tstamp interval [read-write]
1092		1387
1093	The current interval value. Can be modified any time, but changes only	1388	The current interval value. Can be modified any time, but changes only
1094	take effect when the periodic timer fires or C<ev_periodic_again> is being	1389	take effect when the periodic timer fires or C<ev_periodic_again> is being
1095	called.	1390	called.
…		…
1098		1393
1099	The current reschedule callback, or C<0>, if this functionality is	1394	The current reschedule callback, or C<0>, if this functionality is
1100	switched off. Can be changed any time, but changes only take effect when	1395	switched off. Can be changed any time, but changes only take effect when
1101	the periodic timer fires or C<ev_periodic_again> is being called.	1396	the periodic timer fires or C<ev_periodic_again> is being called.
1102		1397
		1398	=item ev_tstamp at [read-only]
		1399
		1400	When active, contains the absolute time that the watcher is supposed to
		1401	trigger next.
		1402
1103	=back	1403	=back
		1404
		1405	=head3 Examples
1104		1406
1105	Example: Call a callback every hour, or, more precisely, whenever the	1407	Example: Call a callback every hour, or, more precisely, whenever the
1106	system clock is divisible by 3600. The callback invocation times have	1408	system clock is divisible by 3600. The callback invocation times have
1107	potentially a lot of jittering, but good long-term stability.	1409	potentially a lot of jittering, but good long-term stability.
1108		1410
…		…
1148	with the kernel (thus it coexists with your own signal handlers as long	1450	with the kernel (thus it coexists with your own signal handlers as long
1149	as you don't register any with libev). Similarly, when the last signal	1451	as you don't register any with libev). Similarly, when the last signal
1150	watcher for a signal is stopped libev will reset the signal handler to	1452	watcher for a signal is stopped libev will reset the signal handler to
1151	SIG_DFL (regardless of what it was set to before).	1453	SIG_DFL (regardless of what it was set to before).
1152		1454
		1455	If possible and supported, libev will install its handlers with
		1456	C<SA_RESTART> behaviour enabled, so syscalls should not be unduly
		1457	interrupted. If you have a problem with syscalls getting interrupted by
		1458	signals you can block all signals in an C<ev_check> watcher and unblock
		1459	them in an C<ev_prepare> watcher.
		1460
		1461	=head3 Watcher-Specific Functions and Data Members
		1462
1153	=over 4	1463	=over 4
1154		1464
1155	=item ev_signal_init (ev_signal *, callback, int signum)	1465	=item ev_signal_init (ev_signal *, callback, int signum)
1156		1466
1157	=item ev_signal_set (ev_signal *, int signum)	1467	=item ev_signal_set (ev_signal *, int signum)
…		…
1163		1473
1164	The signal the watcher watches out for.	1474	The signal the watcher watches out for.
1165		1475
1166	=back	1476	=back
1167		1477
		1478	=head3 Examples
		1479
		1480	Example: Try to exit cleanly on SIGINT and SIGTERM.
		1481
		1482	static void
		1483	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
		1484	{
		1485	ev_unloop (loop, EVUNLOOP_ALL);
		1486	}
		1487
		1488	struct ev_signal signal_watcher;
		1489	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
		1490	ev_signal_start (loop, &sigint_cb);
		1491
1168		1492
1169	=head2 C<ev_child> - watch out for process status changes	1493	=head2 C<ev_child> - watch out for process status changes
1170		1494
1171	Child watchers trigger when your process receives a SIGCHLD in response to	1495	Child watchers trigger when your process receives a SIGCHLD in response to
1172	some child status changes (most typically when a child of yours dies).	1496	some child status changes (most typically when a child of yours dies). It
		1497	is permissible to install a child watcher I<after> the child has been
		1498	forked (which implies it might have already exited), as long as the event
		1499	loop isn't entered (or is continued from a watcher).
		1500
		1501	Only the default event loop is capable of handling signals, and therefore
		1502	you can only rgeister child watchers in the default event loop.
		1503
		1504	=head3 Process Interaction
		1505
		1506	Libev grabs C<SIGCHLD> as soon as the default event loop is
		1507	initialised. This is necessary to guarantee proper behaviour even if
		1508	the first child watcher is started after the child exits. The occurance
		1509	of C<SIGCHLD> is recorded asynchronously, but child reaping is done
		1510	synchronously as part of the event loop processing. Libev always reaps all
		1511	children, even ones not watched.
		1512
		1513	=head3 Overriding the Built-In Processing
		1514
		1515	Libev offers no special support for overriding the built-in child
		1516	processing, but if your application collides with libev's default child
		1517	handler, you can override it easily by installing your own handler for
		1518	C<SIGCHLD> after initialising the default loop, and making sure the
		1519	default loop never gets destroyed. You are encouraged, however, to use an
		1520	event-based approach to child reaping and thus use libev's support for
		1521	that, so other libev users can use C<ev_child> watchers freely.
		1522
		1523	=head3 Watcher-Specific Functions and Data Members
1173		1524
1174	=over 4	1525	=over 4
1175		1526
1176	=item ev_child_init (ev_child *, callback, int pid)	1527	=item ev_child_init (ev_child *, callback, int pid, int trace)
1177		1528
1178	=item ev_child_set (ev_child *, int pid)	1529	=item ev_child_set (ev_child *, int pid, int trace)
1179		1530
1180	Configures the watcher to wait for status changes of process C<pid> (or	1531	Configures the watcher to wait for status changes of process C<pid> (or
1181	I<any> process if C<pid> is specified as C<0>). The callback can look	1532	I<any> process if C<pid> is specified as C<0>). The callback can look
1182	at the C<rstatus> member of the C<ev_child> watcher structure to see	1533	at the C<rstatus> member of the C<ev_child> watcher structure to see
1183	the status word (use the macros from C<sys/wait.h> and see your systems	1534	the status word (use the macros from C<sys/wait.h> and see your systems
1184	C<waitpid> documentation). The C<rpid> member contains the pid of the	1535	C<waitpid> documentation). The C<rpid> member contains the pid of the
1185	process causing the status change.	1536	process causing the status change. C<trace> must be either C<0> (only
		1537	activate the watcher when the process terminates) or C<1> (additionally
		1538	activate the watcher when the process is stopped or continued).
1186		1539
1187	=item int pid [read-only]	1540	=item int pid [read-only]
1188		1541
1189	The process id this watcher watches out for, or C<0>, meaning any process id.	1542	The process id this watcher watches out for, or C<0>, meaning any process id.
1190		1543
…		…
1197	The process exit/trace status caused by C<rpid> (see your systems	1550	The process exit/trace status caused by C<rpid> (see your systems
1198	C<waitpid> and C<sys/wait.h> documentation for details).	1551	C<waitpid> and C<sys/wait.h> documentation for details).
1199		1552
1200	=back	1553	=back
1201		1554
1202	Example: Try to exit cleanly on SIGINT and SIGTERM.	1555	=head3 Examples
		1556
		1557	Example: C<fork()> a new process and install a child handler to wait for
		1558	its completion.
		1559
		1560	ev_child cw;
1203		1561
1204	static void	1562	static void
1205	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)	1563	child_cb (EV_P_ struct ev_child *w, int revents)
1206	{	1564	{
1207	ev_unloop (loop, EVUNLOOP_ALL);	1565	ev_child_stop (EV_A_ w);
		1566	printf ("process %d exited with status %x\n", w->rpid, w->rstatus);
1208	}	1567	}
1209		1568
1210	struct ev_signal signal_watcher;	1569	pid_t pid = fork ();
1211	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1570
1212	ev_signal_start (loop, &sigint_cb);	1571	if (pid < 0)
		1572	// error
		1573	else if (pid == 0)
		1574	{
		1575	// the forked child executes here
		1576	exit (1);
		1577	}
		1578	else
		1579	{
		1580	ev_child_init (&cw, child_cb, pid, 0);
		1581	ev_child_start (EV_DEFAULT_ &cw);
		1582	}
1213		1583
1214		1584
1215	=head2 C<ev_stat> - did the file attributes just change?	1585	=head2 C<ev_stat> - did the file attributes just change?
1216		1586
1217	This watches a filesystem path for attribute changes. That is, it calls	1587	This watches a filesystem path for attribute changes. That is, it calls
…		…
1221	The path does not need to exist: changing from "path exists" to "path does	1591	The path does not need to exist: changing from "path exists" to "path does
1222	not exist" is a status change like any other. The condition "path does	1592	not exist" is a status change like any other. The condition "path does
1223	not exist" is signified by the C<st_nlink> field being zero (which is	1593	not exist" is signified by the C<st_nlink> field being zero (which is
1224	otherwise always forced to be at least one) and all the other fields of	1594	otherwise always forced to be at least one) and all the other fields of
1225	the stat buffer having unspecified contents.	1595	the stat buffer having unspecified contents.
		1596
		1597	The path I<should> be absolute and I<must not> end in a slash. If it is
		1598	relative and your working directory changes, the behaviour is undefined.
1226		1599
1227	Since there is no standard to do this, the portable implementation simply	1600	Since there is no standard to do this, the portable implementation simply
1228	calls C<stat (2)> regularly on the path to see if it changed somehow. You	1601	calls C<stat (2)> regularly on the path to see if it changed somehow. You
1229	can specify a recommended polling interval for this case. If you specify	1602	can specify a recommended polling interval for this case. If you specify
1230	a polling interval of C<0> (highly recommended!) then a I<suitable,	1603	a polling interval of C<0> (highly recommended!) then a I<suitable,
…		…
1243	semantics of C<ev_stat> watchers, which means that libev sometimes needs	1616	semantics of C<ev_stat> watchers, which means that libev sometimes needs
1244	to fall back to regular polling again even with inotify, but changes are	1617	to fall back to regular polling again even with inotify, but changes are
1245	usually detected immediately, and if the file exists there will be no	1618	usually detected immediately, and if the file exists there will be no
1246	polling.	1619	polling.
1247		1620
		1621	=head3 ABI Issues (Largefile Support)
		1622
		1623	Libev by default (unless the user overrides this) uses the default
		1624	compilation environment, which means that on systems with optionally
		1625	disabled large file support, you get the 32 bit version of the stat
		1626	structure. When using the library from programs that change the ABI to
		1627	use 64 bit file offsets the programs will fail. In that case you have to
		1628	compile libev with the same flags to get binary compatibility. This is
		1629	obviously the case with any flags that change the ABI, but the problem is
		1630	most noticably with ev_stat and largefile support.
		1631
		1632	=head3 Inotify
		1633
		1634	When C<inotify (7)> support has been compiled into libev (generally only
		1635	available on Linux) and present at runtime, it will be used to speed up
		1636	change detection where possible. The inotify descriptor will be created lazily
		1637	when the first C<ev_stat> watcher is being started.
		1638
		1639	Inotify presense does not change the semantics of C<ev_stat> watchers
		1640	except that changes might be detected earlier, and in some cases, to avoid
		1641	making regular C<stat> calls. Even in the presense of inotify support
		1642	there are many cases where libev has to resort to regular C<stat> polling.
		1643
		1644	(There is no support for kqueue, as apparently it cannot be used to
		1645	implement this functionality, due to the requirement of having a file
		1646	descriptor open on the object at all times).
		1647
		1648	=head3 The special problem of stat time resolution
		1649
		1650	The C<stat ()> syscall only supports full-second resolution portably, and
		1651	even on systems where the resolution is higher, many filesystems still
		1652	only support whole seconds.
		1653
		1654	That means that, if the time is the only thing that changes, you might
		1655	miss updates: on the first update, C<ev_stat> detects a change and calls
		1656	your callback, which does something. When there is another update within
		1657	the same second, C<ev_stat> will be unable to detect it.
		1658
		1659	The solution to this is to delay acting on a change for a second (or till
		1660	the next second boundary), using a roughly one-second delay C<ev_timer>
		1661	(C<ev_timer_set (w, 0., 1.01); ev_timer_again (loop, w)>). The C<.01>
		1662	is added to work around small timing inconsistencies of some operating
		1663	systems.
		1664
		1665	=head3 Watcher-Specific Functions and Data Members
		1666
1248	=over 4	1667	=over 4
1249		1668
1250	=item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)	1669	=item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)
1251		1670
1252	=item ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)	1671	=item ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)
…		…
1259		1678
1260	The callback will be receive C<EV_STAT> when a change was detected,	1679	The callback will be receive C<EV_STAT> when a change was detected,
1261	relative to the attributes at the time the watcher was started (or the	1680	relative to the attributes at the time the watcher was started (or the
1262	last change was detected).	1681	last change was detected).
1263		1682
1264	=item ev_stat_stat (ev_stat *)	1683	=item ev_stat_stat (loop, ev_stat *)
1265		1684
1266	Updates the stat buffer immediately with new values. If you change the	1685	Updates the stat buffer immediately with new values. If you change the
1267	watched path in your callback, you could call this fucntion to avoid	1686	watched path in your callback, you could call this fucntion to avoid
1268	detecting this change (while introducing a race condition). Can also be	1687	detecting this change (while introducing a race condition). Can also be
1269	useful simply to find out the new values.	1688	useful simply to find out the new values.
…		…
1287	=item const char *path [read-only]	1706	=item const char *path [read-only]
1288		1707
1289	The filesystem path that is being watched.	1708	The filesystem path that is being watched.
1290		1709
1291	=back	1710	=back
		1711
		1712	=head3 Examples
1292		1713
1293	Example: Watch C</etc/passwd> for attribute changes.	1714	Example: Watch C</etc/passwd> for attribute changes.
1294		1715
1295	static void	1716	static void
1296	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)	1717	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
…		…
1309	}	1730	}
1310		1731
1311	...	1732	...
1312	ev_stat passwd;	1733	ev_stat passwd;
1313		1734
1314	ev_stat_init (&passwd, passwd_cb, "/etc/passwd");	1735	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);
1315	ev_stat_start (loop, &passwd);	1736	ev_stat_start (loop, &passwd);
1316		1737
		1738	Example: Like above, but additionally use a one-second delay so we do not
		1739	miss updates (however, frequent updates will delay processing, too, so
		1740	one might do the work both on C<ev_stat> callback invocation I<and> on
		1741	C<ev_timer> callback invocation).
		1742
		1743	static ev_stat passwd;
		1744	static ev_timer timer;
		1745
		1746	static void
		1747	timer_cb (EV_P_ ev_timer *w, int revents)
		1748	{
		1749	ev_timer_stop (EV_A_ w);
		1750
		1751	/* now it's one second after the most recent passwd change */
		1752	}
		1753
		1754	static void
		1755	stat_cb (EV_P_ ev_stat *w, int revents)
		1756	{
		1757	/* reset the one-second timer */
		1758	ev_timer_again (EV_A_ &timer);
		1759	}
		1760
		1761	...
		1762	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);
		1763	ev_stat_start (loop, &passwd);
		1764	ev_timer_init (&timer, timer_cb, 0., 1.01);
		1765
1317		1766
1318	=head2 C<ev_idle> - when you've got nothing better to do...	1767	=head2 C<ev_idle> - when you've got nothing better to do...
1319		1768
1320	Idle watchers trigger events when there are no other events are pending	1769	Idle watchers trigger events when no other events of the same or higher
1321	(prepare, check and other idle watchers do not count). That is, as long	1770	priority are pending (prepare, check and other idle watchers do not
1322	as your process is busy handling sockets or timeouts (or even signals,	1771	count).
1323	imagine) it will not be triggered. But when your process is idle all idle	1772
1324	watchers are being called again and again, once per event loop iteration -	1773	That is, as long as your process is busy handling sockets or timeouts
		1774	(or even signals, imagine) of the same or higher priority it will not be
		1775	triggered. But when your process is idle (or only lower-priority watchers
		1776	are pending), the idle watchers are being called once per event loop
1325	until stopped, that is, or your process receives more events and becomes	1777	iteration - until stopped, that is, or your process receives more events
1326	busy.	1778	and becomes busy again with higher priority stuff.
1327		1779
1328	The most noteworthy effect is that as long as any idle watchers are	1780	The most noteworthy effect is that as long as any idle watchers are
1329	active, the process will not block when waiting for new events.	1781	active, the process will not block when waiting for new events.
1330		1782
1331	Apart from keeping your process non-blocking (which is a useful	1783	Apart from keeping your process non-blocking (which is a useful
1332	effect on its own sometimes), idle watchers are a good place to do	1784	effect on its own sometimes), idle watchers are a good place to do
1333	"pseudo-background processing", or delay processing stuff to after the	1785	"pseudo-background processing", or delay processing stuff to after the
1334	event loop has handled all outstanding events.	1786	event loop has handled all outstanding events.
1335		1787
		1788	=head3 Watcher-Specific Functions and Data Members
		1789
1336	=over 4	1790	=over 4
1337		1791
1338	=item ev_idle_init (ev_signal *, callback)	1792	=item ev_idle_init (ev_signal *, callback)
1339		1793
1340	Initialises and configures the idle watcher - it has no parameters of any	1794	Initialises and configures the idle watcher - it has no parameters of any
1341	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,	1795	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,
1342	believe me.	1796	believe me.
1343		1797
1344	=back	1798	=back
		1799
		1800	=head3 Examples
1345		1801
1346	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the	1802	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1347	callback, free it. Also, use no error checking, as usual.	1803	callback, free it. Also, use no error checking, as usual.
1348		1804
1349	static void	1805	static void
1350	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)	1806	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1351	{	1807	{
1352	free (w);	1808	free (w);
1353	// now do something you wanted to do when the program has	1809	// now do something you wanted to do when the program has
1354	// no longer asnything immediate to do.	1810	// no longer anything immediate to do.
1355	}	1811	}
1356		1812
1357	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));	1813	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1358	ev_idle_init (idle_watcher, idle_cb);	1814	ev_idle_init (idle_watcher, idle_cb);
1359	ev_idle_start (loop, idle_cb);	1815	ev_idle_start (loop, idle_cb);
…		…
1397	with priority higher than or equal to the event loop and one coroutine	1853	with priority higher than or equal to the event loop and one coroutine
1398	of lower priority, but only once, using idle watchers to keep the event	1854	of lower priority, but only once, using idle watchers to keep the event
1399	loop from blocking if lower-priority coroutines are active, thus mapping	1855	loop from blocking if lower-priority coroutines are active, thus mapping
1400	low-priority coroutines to idle/background tasks).	1856	low-priority coroutines to idle/background tasks).
1401		1857
		1858	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)
		1859	priority, to ensure that they are being run before any other watchers
		1860	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,
		1861	too) should not activate ("feed") events into libev. While libev fully
		1862	supports this, they will be called before other C<ev_check> watchers
		1863	did their job. As C<ev_check> watchers are often used to embed other
		1864	(non-libev) event loops those other event loops might be in an unusable
		1865	state until their C<ev_check> watcher ran (always remind yourself to
		1866	coexist peacefully with others).
		1867
		1868	=head3 Watcher-Specific Functions and Data Members
		1869
1402	=over 4	1870	=over 4
1403		1871
1404	=item ev_prepare_init (ev_prepare *, callback)	1872	=item ev_prepare_init (ev_prepare *, callback)
1405		1873
1406	=item ev_check_init (ev_check *, callback)	1874	=item ev_check_init (ev_check *, callback)
…		…
1409	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>	1877	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>
1410	macros, but using them is utterly, utterly and completely pointless.	1878	macros, but using them is utterly, utterly and completely pointless.
1411		1879
1412	=back	1880	=back
1413		1881
1414	Example: To include a library such as adns, you would add IO watchers	1882	=head3 Examples
1415	and a timeout watcher in a prepare handler, as required by libadns, and	1883
		1884	There are a number of principal ways to embed other event loops or modules
		1885	into libev. Here are some ideas on how to include libadns into libev
		1886	(there is a Perl module named C<EV::ADNS> that does this, which you could
		1887	use for an actually working example. Another Perl module named C<EV::Glib>
		1888	embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV
		1889	into the Glib event loop).
		1890
		1891	Method 1: Add IO watchers and a timeout watcher in a prepare handler,
1416	in a check watcher, destroy them and call into libadns. What follows is	1892	and in a check watcher, destroy them and call into libadns. What follows
1417	pseudo-code only of course:	1893	is pseudo-code only of course. This requires you to either use a low
		1894	priority for the check watcher or use C<ev_clear_pending> explicitly, as
		1895	the callbacks for the IO/timeout watchers might not have been called yet.
1418		1896
1419	static ev_io iow [nfd];	1897	static ev_io iow [nfd];
1420	static ev_timer tw;	1898	static ev_timer tw;
1421		1899
1422	static void	1900	static void
1423	io_cb (ev_loop *loop, ev_io *w, int revents)	1901	io_cb (ev_loop *loop, ev_io *w, int revents)
1424	{	1902	{
1425	// set the relevant poll flags
1426	// could also call adns_processreadable etc. here
1427	struct pollfd *fd = (struct pollfd *)w->data;
1428	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1429	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1430	}	1903	}
1431		1904
1432	// create io watchers for each fd and a timer before blocking	1905	// create io watchers for each fd and a timer before blocking
1433	static void	1906	static void
1434	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)	1907	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1435	{	1908	{
1436	int timeout = 3600000;truct pollfd fds [nfd];	1909	int timeout = 3600000;
		1910	struct pollfd fds [nfd];
1437	// actual code will need to loop here and realloc etc.	1911	// actual code will need to loop here and realloc etc.
1438	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1912	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1439		1913
1440	/* the callback is illegal, but won't be called as we stop during check */	1914	/* the callback is illegal, but won't be called as we stop during check */
1441	ev_timer_init (&tw, 0, timeout * 1e-3);	1915	ev_timer_init (&tw, 0, timeout * 1e-3);
1442	ev_timer_start (loop, &tw);	1916	ev_timer_start (loop, &tw);
1443		1917
1444	// create on ev_io per pollfd	1918	// create one ev_io per pollfd
1445	for (int i = 0; i < nfd; ++i)	1919	for (int i = 0; i < nfd; ++i)
1446	{	1920	{
1447	ev_io_init (iow + i, io_cb, fds [i].fd,	1921	ev_io_init (iow + i, io_cb, fds [i].fd,
1448	((fds [i].events & POLLIN ? EV_READ : 0)	1922	((fds [i].events & POLLIN ? EV_READ : 0)
1449	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	1923	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1450		1924
1451	fds [i].revents = 0;	1925	fds [i].revents = 0;
1452	iow [i].data = fds + i;
1453	ev_io_start (loop, iow + i);	1926	ev_io_start (loop, iow + i);
1454	}	1927	}
1455	}	1928	}
1456		1929
1457	// stop all watchers after blocking	1930	// stop all watchers after blocking
…		…
1459	adns_check_cb (ev_loop *loop, ev_check *w, int revents)	1932	adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1460	{	1933	{
1461	ev_timer_stop (loop, &tw);	1934	ev_timer_stop (loop, &tw);
1462		1935
1463	for (int i = 0; i < nfd; ++i)	1936	for (int i = 0; i < nfd; ++i)
		1937	{
		1938	// set the relevant poll flags
		1939	// could also call adns_processreadable etc. here
		1940	struct pollfd *fd = fds + i;
		1941	int revents = ev_clear_pending (iow + i);
		1942	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
		1943	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
		1944
		1945	// now stop the watcher
1464	ev_io_stop (loop, iow + i);	1946	ev_io_stop (loop, iow + i);
		1947	}
1465		1948
1466	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	1949	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1950	}
		1951
		1952	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
		1953	in the prepare watcher and would dispose of the check watcher.
		1954
		1955	Method 3: If the module to be embedded supports explicit event
		1956	notification (adns does), you can also make use of the actual watcher
		1957	callbacks, and only destroy/create the watchers in the prepare watcher.
		1958
		1959	static void
		1960	timer_cb (EV_P_ ev_timer *w, int revents)
		1961	{
		1962	adns_state ads = (adns_state)w->data;
		1963	update_now (EV_A);
		1964
		1965	adns_processtimeouts (ads, &tv_now);
		1966	}
		1967
		1968	static void
		1969	io_cb (EV_P_ ev_io *w, int revents)
		1970	{
		1971	adns_state ads = (adns_state)w->data;
		1972	update_now (EV_A);
		1973
		1974	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
		1975	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
		1976	}
		1977
		1978	// do not ever call adns_afterpoll
		1979
		1980	Method 4: Do not use a prepare or check watcher because the module you
		1981	want to embed is too inflexible to support it. Instead, youc na override
		1982	their poll function. The drawback with this solution is that the main
		1983	loop is now no longer controllable by EV. The C<Glib::EV> module does
		1984	this.
		1985
		1986	static gint
		1987	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
		1988	{
		1989	int got_events = 0;
		1990
		1991	for (n = 0; n < nfds; ++n)
		1992	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
		1993
		1994	if (timeout >= 0)
		1995	// create/start timer
		1996
		1997	// poll
		1998	ev_loop (EV_A_ 0);
		1999
		2000	// stop timer again
		2001	if (timeout >= 0)
		2002	ev_timer_stop (EV_A_ &to);
		2003
		2004	// stop io watchers again - their callbacks should have set
		2005	for (n = 0; n < nfds; ++n)
		2006	ev_io_stop (EV_A_ iow [n]);
		2007
		2008	return got_events;
1467	}	2009	}
1468		2010
1469		2011
1470	=head2 C<ev_embed> - when one backend isn't enough...	2012	=head2 C<ev_embed> - when one backend isn't enough...
1471		2013
…		…
1514	portable one.	2056	portable one.
1515		2057
1516	So when you want to use this feature you will always have to be prepared	2058	So when you want to use this feature you will always have to be prepared
1517	that you cannot get an embeddable loop. The recommended way to get around	2059	that you cannot get an embeddable loop. The recommended way to get around
1518	this is to have a separate variables for your embeddable loop, try to	2060	this is to have a separate variables for your embeddable loop, try to
1519	create it, and if that fails, use the normal loop for everything:	2061	create it, and if that fails, use the normal loop for everything.
		2062
		2063	=head3 Watcher-Specific Functions and Data Members
		2064
		2065	=over 4
		2066
		2067	=item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)
		2068
		2069	=item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)
		2070
		2071	Configures the watcher to embed the given loop, which must be
		2072	embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be
		2073	invoked automatically, otherwise it is the responsibility of the callback
		2074	to invoke it (it will continue to be called until the sweep has been done,
		2075	if you do not want thta, you need to temporarily stop the embed watcher).
		2076
		2077	=item ev_embed_sweep (loop, ev_embed *)
		2078
		2079	Make a single, non-blocking sweep over the embedded loop. This works
		2080	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
		2081	apropriate way for embedded loops.
		2082
		2083	=item struct ev_loop *other [read-only]
		2084
		2085	The embedded event loop.
		2086
		2087	=back
		2088
		2089	=head3 Examples
		2090
		2091	Example: Try to get an embeddable event loop and embed it into the default
		2092	event loop. If that is not possible, use the default loop. The default
		2093	loop is stored in C<loop_hi>, while the mebeddable loop is stored in
		2094	C<loop_lo> (which is C<loop_hi> in the acse no embeddable loop can be
		2095	used).
1520		2096
1521	struct ev_loop *loop_hi = ev_default_init (0);	2097	struct ev_loop *loop_hi = ev_default_init (0);
1522	struct ev_loop *loop_lo = 0;	2098	struct ev_loop *loop_lo = 0;
1523	struct ev_embed embed;	2099	struct ev_embed embed;
1524		2100
…		…
1535	ev_embed_start (loop_hi, &embed);	2111	ev_embed_start (loop_hi, &embed);
1536	}	2112	}
1537	else	2113	else
1538	loop_lo = loop_hi;	2114	loop_lo = loop_hi;
1539		2115
1540	=over 4	2116	Example: Check if kqueue is available but not recommended and create
		2117	a kqueue backend for use with sockets (which usually work with any
		2118	kqueue implementation). Store the kqueue/socket-only event loop in
		2119	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).
1541		2120
1542	=item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)	2121	struct ev_loop *loop = ev_default_init (0);
		2122	struct ev_loop *loop_socket = 0;
		2123	struct ev_embed embed;
		2124
		2125	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)
		2126	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))
		2127	{
		2128	ev_embed_init (&embed, 0, loop_socket);
		2129	ev_embed_start (loop, &embed);
		2130	}
1543		2131
1544	=item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)	2132	if (!loop_socket)
		2133	loop_socket = loop;
1545		2134
1546	Configures the watcher to embed the given loop, which must be	2135	// now use loop_socket for all sockets, and loop for everything else
1547	embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be
1548	invoked automatically, otherwise it is the responsibility of the callback
1549	to invoke it (it will continue to be called until the sweep has been done,
1550	if you do not want thta, you need to temporarily stop the embed watcher).
1551
1552	=item ev_embed_sweep (loop, ev_embed *)
1553
1554	Make a single, non-blocking sweep over the embedded loop. This works
1555	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
1556	apropriate way for embedded loops.
1557
1558	=item struct ev_loop *loop [read-only]
1559
1560	The embedded event loop.
1561
1562	=back
1563		2136
1564		2137
1565	=head2 C<ev_fork> - the audacity to resume the event loop after a fork	2138	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
1566		2139
1567	Fork watchers are called when a C<fork ()> was detected (usually because	2140	Fork watchers are called when a C<fork ()> was detected (usually because
…		…
1570	event loop blocks next and before C<ev_check> watchers are being called,	2143	event loop blocks next and before C<ev_check> watchers are being called,
1571	and only in the child after the fork. If whoever good citizen calling	2144	and only in the child after the fork. If whoever good citizen calling
1572	C<ev_default_fork> cheats and calls it in the wrong process, the fork	2145	C<ev_default_fork> cheats and calls it in the wrong process, the fork
1573	handlers will be invoked, too, of course.	2146	handlers will be invoked, too, of course.
1574		2147
		2148	=head3 Watcher-Specific Functions and Data Members
		2149
1575	=over 4	2150	=over 4
1576		2151
1577	=item ev_fork_init (ev_signal *, callback)	2152	=item ev_fork_init (ev_signal *, callback)
1578		2153
1579	Initialises and configures the fork watcher - it has no parameters of any	2154	Initialises and configures the fork watcher - it has no parameters of any
1580	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,	2155	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
1581	believe me.	2156	believe me.
		2157
		2158	=back
		2159
		2160
		2161	=head2 C<ev_async> - how to wake up another event loop
		2162
		2163	In general, you cannot use an C<ev_loop> from multiple threads or other
		2164	asynchronous sources such as signal handlers (as opposed to multiple event
		2165	loops - those are of course safe to use in different threads).
		2166
		2167	Sometimes, however, you need to wake up another event loop you do not
		2168	control, for example because it belongs to another thread. This is what
		2169	C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you
		2170	can signal it by calling C<ev_async_send>, which is thread- and signal
		2171	safe.
		2172
		2173	This functionality is very similar to C<ev_signal> watchers, as signals,
		2174	too, are asynchronous in nature, and signals, too, will be compressed
		2175	(i.e. the number of callback invocations may be less than the number of
		2176	C<ev_async_sent> calls).
		2177
		2178	Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not
		2179	just the default loop.
		2180
		2181	=head3 Queueing
		2182
		2183	C<ev_async> does not support queueing of data in any way. The reason
		2184	is that the author does not know of a simple (or any) algorithm for a
		2185	multiple-writer-single-reader queue that works in all cases and doesn't
		2186	need elaborate support such as pthreads.
		2187
		2188	That means that if you want to queue data, you have to provide your own
		2189	queue. But at least I can tell you would implement locking around your
		2190	queue:
		2191
		2192	=over 4
		2193
		2194	=item queueing from a signal handler context
		2195
		2196	To implement race-free queueing, you simply add to the queue in the signal
		2197	handler but you block the signal handler in the watcher callback. Here is an example that does that for
		2198	some fictitiuous SIGUSR1 handler:
		2199
		2200	static ev_async mysig;
		2201
		2202	static void
		2203	sigusr1_handler (void)
		2204	{
		2205	sometype data;
		2206
		2207	// no locking etc.
		2208	queue_put (data);
		2209	ev_async_send (EV_DEFAULT_ &mysig);
		2210	}
		2211
		2212	static void
		2213	mysig_cb (EV_P_ ev_async *w, int revents)
		2214	{
		2215	sometype data;
		2216	sigset_t block, prev;
		2217
		2218	sigemptyset (&block);
		2219	sigaddset (&block, SIGUSR1);
		2220	sigprocmask (SIG_BLOCK, &block, &prev);
		2221
		2222	while (queue_get (&data))
		2223	process (data);
		2224
		2225	if (sigismember (&prev, SIGUSR1)
		2226	sigprocmask (SIG_UNBLOCK, &block, 0);
		2227	}
		2228
		2229	(Note: pthreads in theory requires you to use C<pthread_setmask>
		2230	instead of C<sigprocmask> when you use threads, but libev doesn't do it
		2231	either...).
		2232
		2233	=item queueing from a thread context
		2234
		2235	The strategy for threads is different, as you cannot (easily) block
		2236	threads but you can easily preempt them, so to queue safely you need to
		2237	employ a traditional mutex lock, such as in this pthread example:
		2238
		2239	static ev_async mysig;
		2240	static pthread_mutex_t mymutex = PTHREAD_MUTEX_INITIALIZER;
		2241
		2242	static void
		2243	otherthread (void)
		2244	{
		2245	// only need to lock the actual queueing operation
		2246	pthread_mutex_lock (&mymutex);
		2247	queue_put (data);
		2248	pthread_mutex_unlock (&mymutex);
		2249
		2250	ev_async_send (EV_DEFAULT_ &mysig);
		2251	}
		2252
		2253	static void
		2254	mysig_cb (EV_P_ ev_async *w, int revents)
		2255	{
		2256	pthread_mutex_lock (&mymutex);
		2257
		2258	while (queue_get (&data))
		2259	process (data);
		2260
		2261	pthread_mutex_unlock (&mymutex);
		2262	}
		2263
		2264	=back
		2265
		2266
		2267	=head3 Watcher-Specific Functions and Data Members
		2268
		2269	=over 4
		2270
		2271	=item ev_async_init (ev_async *, callback)
		2272
		2273	Initialises and configures the async watcher - it has no parameters of any
		2274	kind. There is a C<ev_asynd_set> macro, but using it is utterly pointless,
		2275	believe me.
		2276
		2277	=item ev_async_send (loop, ev_async *)
		2278
		2279	Sends/signals/activates the given C<ev_async> watcher, that is, feeds
		2280	an C<EV_ASYNC> event on the watcher into the event loop. Unlike
		2281	C<ev_feed_event>, this call is safe to do in other threads, signal or
		2282	similar contexts (see the dicusssion of C<EV_ATOMIC_T> in the embedding
		2283	section below on what exactly this means).
		2284
		2285	This call incurs the overhead of a syscall only once per loop iteration,
		2286	so while the overhead might be noticable, it doesn't apply to repeated
		2287	calls to C<ev_async_send>.
		2288
		2289	=item bool = ev_async_pending (ev_async *)
		2290
		2291	Returns a non-zero value when C<ev_async_send> has been called on the
		2292	watcher but the event has not yet been processed (or even noted) by the
		2293	event loop.
		2294
		2295	C<ev_async_send> sets a flag in the watcher and wakes up the loop. When
		2296	the loop iterates next and checks for the watcher to have become active,
		2297	it will reset the flag again. C<ev_async_pending> can be used to very
		2298	quickly check wether invoking the loop might be a good idea.
		2299
		2300	Not that this does I<not> check wether the watcher itself is pending, only
		2301	wether it has been requested to make this watcher pending.
1582		2302
1583	=back	2303	=back
1584		2304
1585		2305
1586	=head1 OTHER FUNCTIONS	2306	=head1 OTHER FUNCTIONS
…		…
1675		2395
1676	To use it,	2396	To use it,
1677		2397
1678	#include <ev++.h>	2398	#include <ev++.h>
1679		2399
1680	(it is not installed by default). This automatically includes F<ev.h>	2400	This automatically includes F<ev.h> and puts all of its definitions (many
1681	and puts all of its definitions (many of them macros) into the global	2401	of them macros) into the global namespace. All C++ specific things are
1682	namespace. All C++ specific things are put into the C<ev> namespace.	2402	put into the C<ev> namespace. It should support all the same embedding
		2403	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
1683		2404
1684	It should support all the same embedding options as F<ev.h>, most notably	2405	Care has been taken to keep the overhead low. The only data member the C++
1685	C<EV_MULTIPLICITY>.	2406	classes add (compared to plain C-style watchers) is the event loop pointer
		2407	that the watcher is associated with (or no additional members at all if
		2408	you disable C<EV_MULTIPLICITY> when embedding libev).
		2409
		2410	Currently, functions, and static and non-static member functions can be
		2411	used as callbacks. Other types should be easy to add as long as they only
		2412	need one additional pointer for context. If you need support for other
		2413	types of functors please contact the author (preferably after implementing
		2414	it).
1686		2415
1687	Here is a list of things available in the C<ev> namespace:	2416	Here is a list of things available in the C<ev> namespace:
1688		2417
1689	=over 4	2418	=over 4
1690		2419
…		…
1706		2435
1707	All of those classes have these methods:	2436	All of those classes have these methods:
1708		2437
1709	=over 4	2438	=over 4
1710		2439
1711	=item ev::TYPE::TYPE (object *, object::method *)	2440	=item ev::TYPE::TYPE ()
1712		2441
1713	=item ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)	2442	=item ev::TYPE::TYPE (struct ev_loop *)
1714		2443
1715	=item ev::TYPE::~TYPE	2444	=item ev::TYPE::~TYPE
1716		2445
1717	The constructor takes a pointer to an object and a method pointer to	2446	The constructor (optionally) takes an event loop to associate the watcher
1718	the event handler callback to call in this class. The constructor calls	2447	with. If it is omitted, it will use C<EV_DEFAULT>.
1719	C<ev_init> for you, which means you have to call the C<set> method	2448
1720	before starting it. If you do not specify a loop then the constructor	2449	The constructor calls C<ev_init> for you, which means you have to call the
1721	automatically associates the default loop with this watcher.	2450	C<set> method before starting it.
		2451
		2452	It will not set a callback, however: You have to call the templated C<set>
		2453	method to set a callback before you can start the watcher.
		2454
		2455	(The reason why you have to use a method is a limitation in C++ which does
		2456	not allow explicit template arguments for constructors).
1722		2457
1723	The destructor automatically stops the watcher if it is active.	2458	The destructor automatically stops the watcher if it is active.
		2459
		2460	=item w->set<class, &class::method> (object *)
		2461
		2462	This method sets the callback method to call. The method has to have a
		2463	signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as
		2464	first argument and the C<revents> as second. The object must be given as
		2465	parameter and is stored in the C<data> member of the watcher.
		2466
		2467	This method synthesizes efficient thunking code to call your method from
		2468	the C callback that libev requires. If your compiler can inline your
		2469	callback (i.e. it is visible to it at the place of the C<set> call and
		2470	your compiler is good :), then the method will be fully inlined into the
		2471	thunking function, making it as fast as a direct C callback.
		2472
		2473	Example: simple class declaration and watcher initialisation
		2474
		2475	struct myclass
		2476	{
		2477	void io_cb (ev::io &w, int revents) { }
		2478	}
		2479
		2480	myclass obj;
		2481	ev::io iow;
		2482	iow.set <myclass, &myclass::io_cb> (&obj);
		2483
		2484	=item w->set<function> (void *data = 0)
		2485
		2486	Also sets a callback, but uses a static method or plain function as
		2487	callback. The optional C<data> argument will be stored in the watcher's
		2488	C<data> member and is free for you to use.
		2489
		2490	The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>.
		2491
		2492	See the method-C<set> above for more details.
		2493
		2494	Example:
		2495
		2496	static void io_cb (ev::io &w, int revents) { }
		2497	iow.set <io_cb> ();
1724		2498
1725	=item w->set (struct ev_loop *)	2499	=item w->set (struct ev_loop *)
1726		2500
1727	Associates a different C<struct ev_loop> with this watcher. You can only	2501	Associates a different C<struct ev_loop> with this watcher. You can only
1728	do this when the watcher is inactive (and not pending either).	2502	do this when the watcher is inactive (and not pending either).
1729		2503
1730	=item w->set ([args])	2504	=item w->set ([args])
1731		2505
1732	Basically the same as C<ev_TYPE_set>, with the same args. Must be	2506	Basically the same as C<ev_TYPE_set>, with the same args. Must be
1733	called at least once. Unlike the C counterpart, an active watcher gets	2507	called at least once. Unlike the C counterpart, an active watcher gets
1734	automatically stopped and restarted.	2508	automatically stopped and restarted when reconfiguring it with this
		2509	method.
1735		2510
1736	=item w->start ()	2511	=item w->start ()
1737		2512
1738	Starts the watcher. Note that there is no C<loop> argument as the	2513	Starts the watcher. Note that there is no C<loop> argument, as the
1739	constructor already takes the loop.	2514	constructor already stores the event loop.
1740		2515
1741	=item w->stop ()	2516	=item w->stop ()
1742		2517
1743	Stops the watcher if it is active. Again, no C<loop> argument.	2518	Stops the watcher if it is active. Again, no C<loop> argument.
1744		2519
1745	=item w->again () C<ev::timer>, C<ev::periodic> only	2520	=item w->again () (C<ev::timer>, C<ev::periodic> only)
1746		2521
1747	For C<ev::timer> and C<ev::periodic>, this invokes the corresponding	2522	For C<ev::timer> and C<ev::periodic>, this invokes the corresponding
1748	C<ev_TYPE_again> function.	2523	C<ev_TYPE_again> function.
1749		2524
1750	=item w->sweep () C<ev::embed> only	2525	=item w->sweep () (C<ev::embed> only)
1751		2526
1752	Invokes C<ev_embed_sweep>.	2527	Invokes C<ev_embed_sweep>.
1753		2528
1754	=item w->update () C<ev::stat> only	2529	=item w->update () (C<ev::stat> only)
1755		2530
1756	Invokes C<ev_stat_stat>.	2531	Invokes C<ev_stat_stat>.
1757		2532
1758	=back	2533	=back
1759		2534
…		…
1762	Example: Define a class with an IO and idle watcher, start one of them in	2537	Example: Define a class with an IO and idle watcher, start one of them in
1763	the constructor.	2538	the constructor.
1764		2539
1765	class myclass	2540	class myclass
1766	{	2541	{
1767	ev_io io; void io_cb (ev::io &w, int revents);	2542	ev::io io; void io_cb (ev::io &w, int revents);
1768	ev_idle idle void idle_cb (ev::idle &w, int revents);	2543	ev:idle idle void idle_cb (ev::idle &w, int revents);
1769		2544
1770	myclass ();	2545	myclass (int fd)
1771	}
1772
1773	myclass::myclass (int fd)
1774	: io (this, &myclass::io_cb),
1775	idle (this, &myclass::idle_cb)
1776	{	2546	{
		2547	io .set <myclass, &myclass::io_cb > (this);
		2548	idle.set <myclass, &myclass::idle_cb> (this);
		2549
1777	io.start (fd, ev::READ);	2550	io.start (fd, ev::READ);
		2551	}
1778	}	2552	};
		2553
		2554
		2555	=head1 OTHER LANGUAGE BINDINGS
		2556
		2557	Libev does not offer other language bindings itself, but bindings for a
		2558	numbe rof languages exist in the form of third-party packages. If you know
		2559	any interesting language binding in addition to the ones listed here, drop
		2560	me a note.
		2561
		2562	=over 4
		2563
		2564	=item Perl
		2565
		2566	The EV module implements the full libev API and is actually used to test
		2567	libev. EV is developed together with libev. Apart from the EV core module,
		2568	there are additional modules that implement libev-compatible interfaces
		2569	to C<libadns> (C<EV::ADNS>), C<Net::SNMP> (C<Net::SNMP::EV>) and the
		2570	C<libglib> event core (C<Glib::EV> and C<EV::Glib>).
		2571
		2572	It can be found and installed via CPAN, its homepage is found at
		2573	L<http://software.schmorp.de/pkg/EV>.
		2574
		2575	=item Ruby
		2576
		2577	Tony Arcieri has written a ruby extension that offers access to a subset
		2578	of the libev API and adds filehandle abstractions, asynchronous DNS and
		2579	more on top of it. It can be found via gem servers. Its homepage is at
		2580	L<http://rev.rubyforge.org/>.
		2581
		2582	=item D
		2583
		2584	Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to
		2585	be found at L<http://git.llucax.com.ar/?p=software/ev.d.git;a=summary>.
		2586
		2587	=back
1779		2588
1780		2589
1781	=head1 MACRO MAGIC	2590	=head1 MACRO MAGIC
1782		2591
1783	Libev can be compiled with a variety of options, the most fundemantal is	2592	Libev can be compiled with a variety of options, the most fundamantal
1784	C<EV_MULTIPLICITY>. This option determines wether (most) functions and	2593	of which is C<EV_MULTIPLICITY>. This option determines whether (most)
1785	callbacks have an initial C<struct ev_loop *> argument.	2594	functions and callbacks have an initial C<struct ev_loop *> argument.
1786		2595
1787	To make it easier to write programs that cope with either variant, the	2596	To make it easier to write programs that cope with either variant, the
1788	following macros are defined:	2597	following macros are defined:
1789		2598
1790	=over 4	2599	=over 4
…		…
1820	=item C<EV_DEFAULT>, C<EV_DEFAULT_>	2629	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
1821		2630
1822	Similar to the other two macros, this gives you the value of the default	2631	Similar to the other two macros, this gives you the value of the default
1823	loop, if multiple loops are supported ("ev loop default").	2632	loop, if multiple loops are supported ("ev loop default").
1824		2633
		2634	=item C<EV_DEFAULT_UC>, C<EV_DEFAULT_UC_>
		2635
		2636	Usage identical to C<EV_DEFAULT> and C<EV_DEFAULT_>, but requires that the
		2637	default loop has been initialised (C<UC> == unchecked). Their behaviour
		2638	is undefined when the default loop has not been initialised by a previous
		2639	execution of C<EV_DEFAULT>, C<EV_DEFAULT_> or C<ev_default_init (...)>.
		2640
		2641	It is often prudent to use C<EV_DEFAULT> when initialising the first
		2642	watcher in a function but use C<EV_DEFAULT_UC> afterwards.
		2643
1825	=back	2644	=back
1826		2645
1827	Example: Declare and initialise a check watcher, working regardless of	2646	Example: Declare and initialise a check watcher, utilising the above
1828	wether multiple loops are supported or not.	2647	macros so it will work regardless of whether multiple loops are supported
		2648	or not.
1829		2649
1830	static void	2650	static void
1831	check_cb (EV_P_ ev_timer *w, int revents)	2651	check_cb (EV_P_ ev_timer *w, int revents)
1832	{	2652	{
1833	ev_check_stop (EV_A_ w);	2653	ev_check_stop (EV_A_ w);
…		…
1836	ev_check check;	2656	ev_check check;
1837	ev_check_init (&check, check_cb);	2657	ev_check_init (&check, check_cb);
1838	ev_check_start (EV_DEFAULT_ &check);	2658	ev_check_start (EV_DEFAULT_ &check);
1839	ev_loop (EV_DEFAULT_ 0);	2659	ev_loop (EV_DEFAULT_ 0);
1840		2660
1841
1842	=head1 EMBEDDING	2661	=head1 EMBEDDING
1843		2662
1844	Libev can (and often is) directly embedded into host	2663	Libev can (and often is) directly embedded into host
1845	applications. Examples of applications that embed it include the Deliantra	2664	applications. Examples of applications that embed it include the Deliantra
1846	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)	2665	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
1847	and rxvt-unicode.	2666	and rxvt-unicode.
1848		2667
1849	The goal is to enable you to just copy the neecssary files into your	2668	The goal is to enable you to just copy the necessary files into your
1850	source directory without having to change even a single line in them, so	2669	source directory without having to change even a single line in them, so
1851	you can easily upgrade by simply copying (or having a checked-out copy of	2670	you can easily upgrade by simply copying (or having a checked-out copy of
1852	libev somewhere in your source tree).	2671	libev somewhere in your source tree).
1853		2672
1854	=head2 FILESETS	2673	=head2 FILESETS
…		…
1885	ev_vars.h	2704	ev_vars.h
1886	ev_wrap.h	2705	ev_wrap.h
1887		2706
1888	ev_win32.c required on win32 platforms only	2707	ev_win32.c required on win32 platforms only
1889		2708
1890	ev_select.c only when select backend is enabled (which is by default)	2709	ev_select.c only when select backend is enabled (which is enabled by default)
1891	ev_poll.c only when poll backend is enabled (disabled by default)	2710	ev_poll.c only when poll backend is enabled (disabled by default)
1892	ev_epoll.c only when the epoll backend is enabled (disabled by default)	2711	ev_epoll.c only when the epoll backend is enabled (disabled by default)
1893	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	2712	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
1894	ev_port.c only when the solaris port backend is enabled (disabled by default)	2713	ev_port.c only when the solaris port backend is enabled (disabled by default)
1895		2714
…		…
1924		2743
1925	libev.m4	2744	libev.m4
1926		2745
1927	=head2 PREPROCESSOR SYMBOLS/MACROS	2746	=head2 PREPROCESSOR SYMBOLS/MACROS
1928		2747
1929	Libev can be configured via a variety of preprocessor symbols you have to define	2748	Libev can be configured via a variety of preprocessor symbols you have to
1930	before including any of its files. The default is not to build for multiplicity	2749	define before including any of its files. The default in the absense of
1931	and only include the select backend.	2750	autoconf is noted for every option.
1932		2751
1933	=over 4	2752	=over 4
1934		2753
1935	=item EV_STANDALONE	2754	=item EV_STANDALONE
1936		2755
…		…
1944		2763
1945	If defined to be C<1>, libev will try to detect the availability of the	2764	If defined to be C<1>, libev will try to detect the availability of the
1946	monotonic clock option at both compiletime and runtime. Otherwise no use	2765	monotonic clock option at both compiletime and runtime. Otherwise no use
1947	of the monotonic clock option will be attempted. If you enable this, you	2766	of the monotonic clock option will be attempted. If you enable this, you
1948	usually have to link against librt or something similar. Enabling it when	2767	usually have to link against librt or something similar. Enabling it when
1949	the functionality isn't available is safe, though, althoguh you have	2768	the functionality isn't available is safe, though, although you have
1950	to make sure you link against any libraries where the C<clock_gettime>	2769	to make sure you link against any libraries where the C<clock_gettime>
1951	function is hiding in (often F<-lrt>).	2770	function is hiding in (often F<-lrt>).
1952		2771
1953	=item EV_USE_REALTIME	2772	=item EV_USE_REALTIME
1954		2773
1955	If defined to be C<1>, libev will try to detect the availability of the	2774	If defined to be C<1>, libev will try to detect the availability of the
1956	realtime clock option at compiletime (and assume its availability at	2775	realtime clock option at compiletime (and assume its availability at
1957	runtime if successful). Otherwise no use of the realtime clock option will	2776	runtime if successful). Otherwise no use of the realtime clock option will
1958	be attempted. This effectively replaces C<gettimeofday> by C<clock_get	2777	be attempted. This effectively replaces C<gettimeofday> by C<clock_get
1959	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries	2778	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the
1960	in the description of C<EV_USE_MONOTONIC>, though.	2779	note about libraries in the description of C<EV_USE_MONOTONIC>, though.
		2780
		2781	=item EV_USE_NANOSLEEP
		2782
		2783	If defined to be C<1>, libev will assume that C<nanosleep ()> is available
		2784	and will use it for delays. Otherwise it will use C<select ()>.
		2785
		2786	=item EV_USE_EVENTFD
		2787
		2788	If defined to be C<1>, then libev will assume that C<eventfd ()> is
		2789	available and will probe for kernel support at runtime. This will improve
		2790	C<ev_signal> and C<ev_async> performance and reduce resource consumption.
		2791	If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc
		2792	2.7 or newer, otherwise disabled.
1961		2793
1962	=item EV_USE_SELECT	2794	=item EV_USE_SELECT
1963		2795
1964	If undefined or defined to be C<1>, libev will compile in support for the	2796	If undefined or defined to be C<1>, libev will compile in support for the
1965	C<select>(2) backend. No attempt at autodetection will be done: if no	2797	C<select>(2) backend. No attempt at autodetection will be done: if no
…		…
1984	be used is the winsock select). This means that it will call	2816	be used is the winsock select). This means that it will call
1985	C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise,	2817	C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise,
1986	it is assumed that all these functions actually work on fds, even	2818	it is assumed that all these functions actually work on fds, even
1987	on win32. Should not be defined on non-win32 platforms.	2819	on win32. Should not be defined on non-win32 platforms.
1988		2820
		2821	=item EV_FD_TO_WIN32_HANDLE
		2822
		2823	If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map
		2824	file descriptors to socket handles. When not defining this symbol (the
		2825	default), then libev will call C<_get_osfhandle>, which is usually
		2826	correct. In some cases, programs use their own file descriptor management,
		2827	in which case they can provide this function to map fds to socket handles.
		2828
1989	=item EV_USE_POLL	2829	=item EV_USE_POLL
1990		2830
1991	If defined to be C<1>, libev will compile in support for the C<poll>(2)	2831	If defined to be C<1>, libev will compile in support for the C<poll>(2)
1992	backend. Otherwise it will be enabled on non-win32 platforms. It	2832	backend. Otherwise it will be enabled on non-win32 platforms. It
1993	takes precedence over select.	2833	takes precedence over select.
1994		2834
1995	=item EV_USE_EPOLL	2835	=item EV_USE_EPOLL
1996		2836
1997	If defined to be C<1>, libev will compile in support for the Linux	2837	If defined to be C<1>, libev will compile in support for the Linux
1998	C<epoll>(7) backend. Its availability will be detected at runtime,	2838	C<epoll>(7) backend. Its availability will be detected at runtime,
1999	otherwise another method will be used as fallback. This is the	2839	otherwise another method will be used as fallback. This is the preferred
2000	preferred backend for GNU/Linux systems.	2840	backend for GNU/Linux systems. If undefined, it will be enabled if the
		2841	headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled.
2001		2842
2002	=item EV_USE_KQUEUE	2843	=item EV_USE_KQUEUE
2003		2844
2004	If defined to be C<1>, libev will compile in support for the BSD style	2845	If defined to be C<1>, libev will compile in support for the BSD style
2005	C<kqueue>(2) backend. Its actual availability will be detected at runtime,	2846	C<kqueue>(2) backend. Its actual availability will be detected at runtime,
…		…
2024		2865
2025	=item EV_USE_INOTIFY	2866	=item EV_USE_INOTIFY
2026		2867
2027	If defined to be C<1>, libev will compile in support for the Linux inotify	2868	If defined to be C<1>, libev will compile in support for the Linux inotify
2028	interface to speed up C<ev_stat> watchers. Its actual availability will	2869	interface to speed up C<ev_stat> watchers. Its actual availability will
2029	be detected at runtime.	2870	be detected at runtime. If undefined, it will be enabled if the headers
		2871	indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled.
		2872
		2873	=item EV_ATOMIC_T
		2874
		2875	Libev requires an integer type (suitable for storing C<0> or C<1>) whose
		2876	access is atomic with respect to other threads or signal contexts. No such
		2877	type is easily found in the C language, so you can provide your own type
		2878	that you know is safe for your purposes. It is used both for signal handler "locking"
		2879	as well as for signal and thread safety in C<ev_async> watchers.
		2880
		2881	In the absense of this define, libev will use C<sig_atomic_t volatile>
		2882	(from F<signal.h>), which is usually good enough on most platforms.
2030		2883
2031	=item EV_H	2884	=item EV_H
2032		2885
2033	The name of the F<ev.h> header file used to include it. The default if	2886	The name of the F<ev.h> header file used to include it. The default if
2034	undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This	2887	undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be
2035	can be used to virtually rename the F<ev.h> header file in case of conflicts.	2888	used to virtually rename the F<ev.h> header file in case of conflicts.
2036		2889
2037	=item EV_CONFIG_H	2890	=item EV_CONFIG_H
2038		2891
2039	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override	2892	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override
2040	F<ev.c>'s idea of where to find the F<config.h> file, similarly to	2893	F<ev.c>'s idea of where to find the F<config.h> file, similarly to
2041	C<EV_H>, above.	2894	C<EV_H>, above.
2042		2895
2043	=item EV_EVENT_H	2896	=item EV_EVENT_H
2044		2897
2045	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea	2898	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea
2046	of how the F<event.h> header can be found.	2899	of how the F<event.h> header can be found, the default is C<"event.h">.
2047		2900
2048	=item EV_PROTOTYPES	2901	=item EV_PROTOTYPES
2049		2902
2050	If defined to be C<0>, then F<ev.h> will not define any function	2903	If defined to be C<0>, then F<ev.h> will not define any function
2051	prototypes, but still define all the structs and other symbols. This is	2904	prototypes, but still define all the structs and other symbols. This is
…		…
2058	will have the C<struct ev_loop *> as first argument, and you can create	2911	will have the C<struct ev_loop *> as first argument, and you can create
2059	additional independent event loops. Otherwise there will be no support	2912	additional independent event loops. Otherwise there will be no support
2060	for multiple event loops and there is no first event loop pointer	2913	for multiple event loops and there is no first event loop pointer
2061	argument. Instead, all functions act on the single default loop.	2914	argument. Instead, all functions act on the single default loop.
2062		2915
		2916	=item EV_MINPRI
		2917
		2918	=item EV_MAXPRI
		2919
		2920	The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to
		2921	C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can
		2922	provide for more priorities by overriding those symbols (usually defined
		2923	to be C<-2> and C<2>, respectively).
		2924
		2925	When doing priority-based operations, libev usually has to linearly search
		2926	all the priorities, so having many of them (hundreds) uses a lot of space
		2927	and time, so using the defaults of five priorities (-2 .. +2) is usually
		2928	fine.
		2929
		2930	If your embedding app does not need any priorities, defining these both to
		2931	C<0> will save some memory and cpu.
		2932
2063	=item EV_PERIODIC_ENABLE	2933	=item EV_PERIODIC_ENABLE
2064		2934
2065	If undefined or defined to be C<1>, then periodic timers are supported. If	2935	If undefined or defined to be C<1>, then periodic timers are supported. If
2066	defined to be C<0>, then they are not. Disabling them saves a few kB of	2936	defined to be C<0>, then they are not. Disabling them saves a few kB of
2067	code.	2937	code.
2068		2938
		2939	=item EV_IDLE_ENABLE
		2940
		2941	If undefined or defined to be C<1>, then idle watchers are supported. If
		2942	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2943	code.
		2944
2069	=item EV_EMBED_ENABLE	2945	=item EV_EMBED_ENABLE
2070		2946
2071	If undefined or defined to be C<1>, then embed watchers are supported. If	2947	If undefined or defined to be C<1>, then embed watchers are supported. If
2072	defined to be C<0>, then they are not.	2948	defined to be C<0>, then they are not.
2073		2949
…		…
2077	defined to be C<0>, then they are not.	2953	defined to be C<0>, then they are not.
2078		2954
2079	=item EV_FORK_ENABLE	2955	=item EV_FORK_ENABLE
2080		2956
2081	If undefined or defined to be C<1>, then fork watchers are supported. If	2957	If undefined or defined to be C<1>, then fork watchers are supported. If
		2958	defined to be C<0>, then they are not.
		2959
		2960	=item EV_ASYNC_ENABLE
		2961
		2962	If undefined or defined to be C<1>, then async watchers are supported. If
2082	defined to be C<0>, then they are not.	2963	defined to be C<0>, then they are not.
2083		2964
2084	=item EV_MINIMAL	2965	=item EV_MINIMAL
2085		2966
2086	If you need to shave off some kilobytes of code at the expense of some	2967	If you need to shave off some kilobytes of code at the expense of some
…		…
2094	than enough. If you need to manage thousands of children you might want to	2975	than enough. If you need to manage thousands of children you might want to
2095	increase this value (I<must> be a power of two).	2976	increase this value (I<must> be a power of two).
2096		2977
2097	=item EV_INOTIFY_HASHSIZE	2978	=item EV_INOTIFY_HASHSIZE
2098		2979
2099	C<ev_staz> watchers use a small hash table to distribute workload by	2980	C<ev_stat> watchers use a small hash table to distribute workload by
2100	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),	2981	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
2101	usually more than enough. If you need to manage thousands of C<ev_stat>	2982	usually more than enough. If you need to manage thousands of C<ev_stat>
2102	watchers you might want to increase this value (I<must> be a power of	2983	watchers you might want to increase this value (I<must> be a power of
2103	two).	2984	two).
2104		2985
…		…
2121		3002
2122	=item ev_set_cb (ev, cb)	3003	=item ev_set_cb (ev, cb)
2123		3004
2124	Can be used to change the callback member declaration in each watcher,	3005	Can be used to change the callback member declaration in each watcher,
2125	and the way callbacks are invoked and set. Must expand to a struct member	3006	and the way callbacks are invoked and set. Must expand to a struct member
2126	definition and a statement, respectively. See the F<ev.v> header file for	3007	definition and a statement, respectively. See the F<ev.h> header file for
2127	their default definitions. One possible use for overriding these is to	3008	their default definitions. One possible use for overriding these is to
2128	avoid the C<struct ev_loop *> as first argument in all cases, or to use	3009	avoid the C<struct ev_loop *> as first argument in all cases, or to use
2129	method calls instead of plain function calls in C++.	3010	method calls instead of plain function calls in C++.
		3011
		3012	=head2 EXPORTED API SYMBOLS
		3013
		3014	If you need to re-export the API (e.g. via a dll) and you need a list of
		3015	exported symbols, you can use the provided F<Symbol.*> files which list
		3016	all public symbols, one per line:
		3017
		3018	Symbols.ev for libev proper
		3019	Symbols.event for the libevent emulation
		3020
		3021	This can also be used to rename all public symbols to avoid clashes with
		3022	multiple versions of libev linked together (which is obviously bad in
		3023	itself, but sometimes it is inconvinient to avoid this).
		3024
		3025	A sed command like this will create wrapper C<#define>'s that you need to
		3026	include before including F<ev.h>:
		3027
		3028	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h
		3029
		3030	This would create a file F<wrap.h> which essentially looks like this:
		3031
		3032	#define ev_backend myprefix_ev_backend
		3033	#define ev_check_start myprefix_ev_check_start
		3034	#define ev_check_stop myprefix_ev_check_stop
		3035	...
2130		3036
2131	=head2 EXAMPLES	3037	=head2 EXAMPLES
2132		3038
2133	For a real-world example of a program the includes libev	3039	For a real-world example of a program the includes libev
2134	verbatim, you can have a look at the EV perl module	3040	verbatim, you can have a look at the EV perl module
…		…
2137	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file	3043	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file
2138	will be compiled. It is pretty complex because it provides its own header	3044	will be compiled. It is pretty complex because it provides its own header
2139	file.	3045	file.
2140		3046
2141	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	3047	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
2142	that everybody includes and which overrides some autoconf choices:	3048	that everybody includes and which overrides some configure choices:
2143		3049
		3050	#define EV_MINIMAL 1
2144	#define EV_USE_POLL 0	3051	#define EV_USE_POLL 0
2145	#define EV_MULTIPLICITY 0	3052	#define EV_MULTIPLICITY 0
2146	#define EV_PERIODICS 0	3053	#define EV_PERIODIC_ENABLE 0
		3054	#define EV_STAT_ENABLE 0
		3055	#define EV_FORK_ENABLE 0
2147	#define EV_CONFIG_H <config.h>	3056	#define EV_CONFIG_H <config.h>
		3057	#define EV_MINPRI 0
		3058	#define EV_MAXPRI 0
2148		3059
2149	#include "ev++.h"	3060	#include "ev++.h"
2150		3061
2151	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	3062	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
2152		3063
2153	#include "ev_cpp.h"	3064	#include "ev_cpp.h"
2154	#include "ev.c"	3065	#include "ev.c"
		3066
		3067
		3068	=head1 THREADS AND COROUTINES
		3069
		3070	=head2 THREADS
		3071
		3072	Libev itself is completely threadsafe, but it uses no locking. This
		3073	means that you can use as many loops as you want in parallel, as long as
		3074	only one thread ever calls into one libev function with the same loop
		3075	parameter.
		3076
		3077	Or put differently: calls with different loop parameters can be done in
		3078	parallel from multiple threads, calls with the same loop parameter must be
		3079	done serially (but can be done from different threads, as long as only one
		3080	thread ever is inside a call at any point in time, e.g. by using a mutex
		3081	per loop).
		3082
		3083	If you want to know which design is best for your problem, then I cannot
		3084	help you but by giving some generic advice:
		3085
		3086	=over 4
		3087
		3088	=item * most applications have a main thread: use the default libev loop
		3089	in that thread, or create a seperate thread running only the default loop.
		3090
		3091	This helps integrating other libraries or software modules that use libev
		3092	themselves and don't care/know about threading.
		3093
		3094	=item * one loop per thread is usually a good model.
		3095
		3096	Doing this is almost never wrong, sometimes a better-performance model
		3097	exists, but it is always a good start.
		3098
		3099	=item * other models exist, such as the leader/follower pattern, where one
		3100	loop is handed through multiple threads in a kind of round-robbin fashion.
		3101
		3102	Chosing a model is hard - look around, learn, know that usually you cna do
		3103	better than you currently do :-)
		3104
		3105	=item * often you need to talk to some other thread which blocks in the
		3106	event loop - C<ev_async> watchers can be used to wake them up from other
		3107	threads safely (or from signal contexts...).
		3108
		3109	=back
		3110
		3111	=head2 COROUTINES
		3112
		3113	Libev is much more accomodating to coroutines ("cooperative threads"):
		3114	libev fully supports nesting calls to it's functions from different
		3115	coroutines (e.g. you can call C<ev_loop> on the same loop from two
		3116	different coroutines and switch freely between both coroutines running the
		3117	loop, as long as you don't confuse yourself). The only exception is that
		3118	you must not do this from C<ev_periodic> reschedule callbacks.
		3119
		3120	Care has been invested into making sure that libev does not keep local
		3121	state inside C<ev_loop>, and other calls do not usually allow coroutine
		3122	switches.
2155		3123
2156		3124
2157	=head1 COMPLEXITIES	3125	=head1 COMPLEXITIES
2158		3126
2159	In this section the complexities of (many of) the algorithms used inside	3127	In this section the complexities of (many of) the algorithms used inside
2160	libev will be explained. For complexity discussions about backends see the	3128	libev will be explained. For complexity discussions about backends see the
2161	documentation for C<ev_default_init>.	3129	documentation for C<ev_default_init>.
2162		3130
		3131	All of the following are about amortised time: If an array needs to be
		3132	extended, libev needs to realloc and move the whole array, but this
		3133	happens asymptotically never with higher number of elements, so O(1) might
		3134	mean it might do a lengthy realloc operation in rare cases, but on average
		3135	it is much faster and asymptotically approaches constant time.
		3136
2163	=over 4	3137	=over 4
2164		3138
2165	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)	3139	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
2166		3140
		3141	This means that, when you have a watcher that triggers in one hour and
		3142	there are 100 watchers that would trigger before that then inserting will
		3143	have to skip roughly seven (C<ld 100>) of these watchers.
		3144
2167	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)	3145	=item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers)
2168		3146
		3147	That means that changing a timer costs less than removing/adding them
		3148	as only the relative motion in the event queue has to be paid for.
		3149
2169	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	3150	=item Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1)
2170		3151
		3152	These just add the watcher into an array or at the head of a list.
		3153
2171	=item Stopping check/prepare/idle watchers: O(1)	3154	=item Stopping check/prepare/idle/fork/async watchers: O(1)
2172		3155
2173	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))	3156	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
2174		3157
		3158	These watchers are stored in lists then need to be walked to find the
		3159	correct watcher to remove. The lists are usually short (you don't usually
		3160	have many watchers waiting for the same fd or signal).
		3161
2175	=item Finding the next timer per loop iteration: O(1)	3162	=item Finding the next timer in each loop iteration: O(1)
		3163
		3164	By virtue of using a binary heap, the next timer is always found at the
		3165	beginning of the storage array.
2176		3166
2177	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	3167	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
2178		3168
2179	=item Activating one watcher: O(1)	3169	A change means an I/O watcher gets started or stopped, which requires
		3170	libev to recalculate its status (and possibly tell the kernel, depending
		3171	on backend and wether C<ev_io_set> was used).
		3172
		3173	=item Activating one watcher (putting it into the pending state): O(1)
		3174
		3175	=item Priority handling: O(number_of_priorities)
		3176
		3177	Priorities are implemented by allocating some space for each
		3178	priority. When doing priority-based operations, libev usually has to
		3179	linearly search all the priorities, but starting/stopping and activating
		3180	watchers becomes O(1) w.r.t. priority handling.
		3181
		3182	=item Sending an ev_async: O(1)
		3183
		3184	=item Processing ev_async_send: O(number_of_async_watchers)
		3185
		3186	=item Processing signals: O(max_signal_number)
		3187
		3188	Sending involves a syscall I<iff> there were no other C<ev_async_send>
		3189	calls in the current loop iteration. Checking for async and signal events
		3190	involves iterating over all running async watchers or all signal numbers.
2180		3191
2181	=back	3192	=back
2182		3193
2183		3194
		3195	=head1 Win32 platform limitations and workarounds
		3196
		3197	Win32 doesn't support any of the standards (e.g. POSIX) that libev
		3198	requires, and its I/O model is fundamentally incompatible with the POSIX
		3199	model. Libev still offers limited functionality on this platform in
		3200	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
		3201	descriptors. This only applies when using Win32 natively, not when using
		3202	e.g. cygwin.
		3203
		3204	There is no supported compilation method available on windows except
		3205	embedding it into other applications.
		3206
		3207	Due to the many, low, and arbitrary limits on the win32 platform and the
		3208	abysmal performance of winsockets, using a large number of sockets is not
		3209	recommended (and not reasonable). If your program needs to use more than
		3210	a hundred or so sockets, then likely it needs to use a totally different
		3211	implementation for windows, as libev offers the POSIX model, which cannot
		3212	be implemented efficiently on windows (microsoft monopoly games).
		3213
		3214	=over 4
		3215
		3216	=item The winsocket select function
		3217
		3218	The winsocket C<select> function doesn't follow POSIX in that it requires
		3219	socket I<handles> and not socket I<file descriptors>. This makes select
		3220	very inefficient, and also requires a mapping from file descriptors
		3221	to socket handles. See the discussion of the C<EV_SELECT_USE_FD_SET>,
		3222	C<EV_SELECT_IS_WINSOCKET> and C<EV_FD_TO_WIN32_HANDLE> preprocessor
		3223	symbols for more info.
		3224
		3225	The configuration for a "naked" win32 using the microsoft runtime
		3226	libraries and raw winsocket select is:
		3227
		3228	#define EV_USE_SELECT 1
		3229	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
		3230
		3231	Note that winsockets handling of fd sets is O(n), so you can easily get a
		3232	complexity in the O(n²) range when using win32.
		3233
		3234	=item Limited number of file descriptors
		3235
		3236	Windows has numerous arbitrary (and low) limits on things. Early versions
		3237	of winsocket's select only supported waiting for a max. of C<64> handles
		3238	(probably owning to the fact that all windows kernels can only wait for
		3239	C<64> things at the same time internally; microsoft recommends spawning a
		3240	chain of threads and wait for 63 handles and the previous thread in each).
		3241
		3242	Newer versions support more handles, but you need to define C<FD_SETSIZE>
		3243	to some high number (e.g. C<2048>) before compiling the winsocket select
		3244	call (which might be in libev or elsewhere, for example, perl does its own
		3245	select emulation on windows).
		3246
		3247	Another limit is the number of file descriptors in the microsoft runtime
		3248	libraries, which by default is C<64> (there must be a hidden I<64> fetish
		3249	or something like this inside microsoft). You can increase this by calling
		3250	C<_setmaxstdio>, which can increase this limit to C<2048> (another
		3251	arbitrary limit), but is broken in many versions of the microsoft runtime
		3252	libraries.
		3253
		3254	This might get you to about C<512> or C<2048> sockets (depending on
		3255	windows version and/or the phase of the moon). To get more, you need to
		3256	wrap all I/O functions and provide your own fd management, but the cost of
		3257	calling select (O(n²)) will likely make this unworkable.
		3258
		3259	=back
		3260
		3261
2184	=head1 AUTHOR	3262	=head1 AUTHOR
2185		3263
2186	Marc Lehmann <libev@schmorp.de>.	3264	Marc Lehmann <libev@schmorp.de>.
2187		3265

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