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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	=head2 EXAMPLE PROGRAM
		10
		11	#include <ev.h>
		12
		13	ev_io stdin_watcher;
		14	ev_timer timeout_watcher;
		15
		16	/* called when data readable on stdin */
		17	static void
		18	stdin_cb (EV_P_ struct ev_io *w, int revents)
		19	{
		20	/* puts ("stdin ready"); */
		21	ev_io_stop (EV_A_ w); /* just a syntax example */
		22	ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */
		23	}
		24
		25	static void
		26	timeout_cb (EV_P_ struct ev_timer *w, int revents)
		27	{
		28	/* puts ("timeout"); */
		29	ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */
		30	}
		31
		32	int
		33	main (void)
		34	{
		35	struct ev_loop *loop = ev_default_loop (0);
		36
		37	/* initialise an io watcher, then start it */
		38	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);
		39	ev_io_start (loop, &stdin_watcher);
		40
		41	/* simple non-repeating 5.5 second timeout */
		42	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
		43	ev_timer_start (loop, &timeout_watcher);
		44
		45	/* loop till timeout or data ready */
		46	ev_loop (loop, 0);
		47
		48	return 0;
		49	}
		50
9	=head1 DESCRIPTION	51	=head1 DESCRIPTION
10		52
		53	The newest version of this document is also available as a html-formatted
		54	web page you might find easier to navigate when reading it for the first
		55	time: L<http://cvs.schmorp.de/libev/ev.html>.
		56
11	Libev is an event loop: you register interest in certain events (such as a	57	Libev is an event loop: you register interest in certain events (such as a
12	file descriptor being readable or a timeout occuring), and it will manage	58	file descriptor being readable or a timeout occurring), and it will manage
13	these event sources and provide your program with events.	59	these event sources and provide your program with events.
14		60
15	To do this, it must take more or less complete control over your process	61	To do this, it must take more or less complete control over your process
16	(or thread) by executing the I<event loop> handler, and will then	62	(or thread) by executing the I<event loop> handler, and will then
17	communicate events via a callback mechanism.	63	communicate events via a callback mechanism.
…		…
19	You register interest in certain events by registering so-called I<event	65	You register interest in certain events by registering so-called I<event
20	watchers>, which are relatively small C structures you initialise with the	66	watchers>, which are relatively small C structures you initialise with the
21	details of the event, and then hand it over to libev by I<starting> the	67	details of the event, and then hand it over to libev by I<starting> the
22	watcher.	68	watcher.
23		69
24	=head1 FEATURES	70	=head2 FEATURES
25		71
26	Libev supports select, poll, the linux-specific epoll and the bsd-specific	72	Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the
27	kqueue mechanisms for file descriptor events, relative timers, absolute	73	BSD-specific C<kqueue> and the Solaris-specific event port mechanisms
28	timers with customised rescheduling, signal events, process status change	74	for file descriptor events (C<ev_io>), the Linux C<inotify> interface
29	events (related to SIGCHLD), and event watchers dealing with the event	75	(for C<ev_stat>), relative timers (C<ev_timer>), absolute timers
30	loop mechanism itself (idle, prepare and check watchers). It also is quite	76	with customised rescheduling (C<ev_periodic>), synchronous signals
		77	(C<ev_signal>), process status change events (C<ev_child>), and event
		78	watchers dealing with the event loop mechanism itself (C<ev_idle>,
		79	C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as
		80	file watchers (C<ev_stat>) and even limited support for fork events
		81	(C<ev_fork>).
		82
		83	It also is quite fast (see this
31	fast (see this L<benchmark|http://libev.schmorp.de/bench.html> comparing	84	L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent
32	it to libevent for example).	85	for example).
33		86
34	=head1 CONVENTIONS	87	=head2 CONVENTIONS
35		88
36	Libev is very configurable. In this manual the default configuration	89	Libev is very configurable. In this manual the default configuration will
37	will be described, which supports multiple event loops. For more info	90	be described, which supports multiple event loops. For more info about
38	about various configuration options please have a look at the file	91	various configuration options please have a look at B<EMBED> section in
39	F<README.embed> in the libev distribution. If libev was configured without	92	this manual. If libev was configured without support for multiple event
40	support for multiple event loops, then all functions taking an initial	93	loops, then all functions taking an initial argument of name C<loop>
41	argument of name C<loop> (which is always of type C<struct ev_loop *>)	94	(which is always of type C<struct ev_loop *>) will not have this argument.
42	will not have this argument.
43		95
44	=head1 TIME REPRESENTATION	96	=head2 TIME REPRESENTATION
45		97
46	Libev represents time as a single floating point number, representing the	98	Libev represents time as a single floating point number, representing the
47	(fractional) number of seconds since the (POSIX) epoch (somewhere near	99	(fractional) number of seconds since the (POSIX) epoch (somewhere near
48	the beginning of 1970, details are complicated, don't ask). This type is	100	the beginning of 1970, details are complicated, don't ask). This type is
49	called C<ev_tstamp>, which is what you should use too. It usually aliases	101	called C<ev_tstamp>, which is what you should use too. It usually aliases
50	to the C<double> type in C, and when you need to do any calculations on	102	to the C<double> type in C, and when you need to do any calculations on
51	it, you should treat it as such.	103	it, you should treat it as some floatingpoint value. Unlike the name
52		104	component C<stamp> might indicate, it is also used for time differences
		105	throughout libev.
53		106
54	=head1 GLOBAL FUNCTIONS	107	=head1 GLOBAL FUNCTIONS
55		108
56	These functions can be called anytime, even before initialising the	109	These functions can be called anytime, even before initialising the
57	library in any way.	110	library in any way.
…		…
62		115
63	Returns the current time as libev would use it. Please note that the	116	Returns the current time as libev would use it. Please note that the
64	C<ev_now> function is usually faster and also often returns the timestamp	117	C<ev_now> function is usually faster and also often returns the timestamp
65	you actually want to know.	118	you actually want to know.
66		119
		120	=item ev_sleep (ev_tstamp interval)
		121
		122	Sleep for the given interval: The current thread will be blocked until
		123	either it is interrupted or the given time interval has passed. Basically
		124	this is a subsecond-resolution C<sleep ()>.
		125
67	=item int ev_version_major ()	126	=item int ev_version_major ()
68		127
69	=item int ev_version_minor ()	128	=item int ev_version_minor ()
70		129
71	You can find out the major and minor version numbers of the library	130	You can find out the major and minor ABI version numbers of the library
72	you linked against by calling the functions C<ev_version_major> and	131	you linked against by calling the functions C<ev_version_major> and
73	C<ev_version_minor>. If you want, you can compare against the global	132	C<ev_version_minor>. If you want, you can compare against the global
74	symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the	133	symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the
75	version of the library your program was compiled against.	134	version of the library your program was compiled against.
76		135
		136	These version numbers refer to the ABI version of the library, not the
		137	release version.
		138
77	Usually, it's a good idea to terminate if the major versions mismatch,	139	Usually, it's a good idea to terminate if the major versions mismatch,
78	as this indicates an incompatible change. Minor versions are usually	140	as this indicates an incompatible change. Minor versions are usually
79	compatible to older versions, so a larger minor version alone is usually	141	compatible to older versions, so a larger minor version alone is usually
80	not a problem.	142	not a problem.
81		143
82	Example: make sure we haven't accidentally been linked against the wrong	144	Example: Make sure we haven't accidentally been linked against the wrong
83	version:	145	version.
84		146
85	assert (("libev version mismatch",	147	assert (("libev version mismatch",
86	ev_version_major () == EV_VERSION_MAJOR	148	ev_version_major () == EV_VERSION_MAJOR
87	&& ev_version_minor () >= EV_VERSION_MINOR));	149	&& ev_version_minor () >= EV_VERSION_MINOR));
88		150
…		…
118		180
119	See the description of C<ev_embed> watchers for more info.	181	See the description of C<ev_embed> watchers for more info.
120		182
121	=item ev_set_allocator (void *(*cb)(void *ptr, long size))	183	=item ev_set_allocator (void *(*cb)(void *ptr, long size))
122		184
123	Sets the allocation function to use (the prototype is similar to the	185	Sets the allocation function to use (the prototype is similar - the
124	realloc C function, the semantics are identical). It is used to allocate	186	semantics is identical - to the realloc C function). It is used to
125	and free memory (no surprises here). If it returns zero when memory	187	allocate and free memory (no surprises here). If it returns zero when
126	needs to be allocated, the library might abort or take some potentially	188	memory needs to be allocated, the library might abort or take some
127	destructive action. The default is your system realloc function.	189	potentially destructive action. The default is your system realloc
		190	function.
128		191
129	You could override this function in high-availability programs to, say,	192	You could override this function in high-availability programs to, say,
130	free some memory if it cannot allocate memory, to use a special allocator,	193	free some memory if it cannot allocate memory, to use a special allocator,
131	or even to sleep a while and retry until some memory is available.	194	or even to sleep a while and retry until some memory is available.
132		195
133	Example: replace the libev allocator with one that waits a bit and then	196	Example: Replace the libev allocator with one that waits a bit and then
134	retries: better than mine).	197	retries).
135		198
136	static void *	199	static void *
137	persistent_realloc (void *ptr, long size)	200	persistent_realloc (void *ptr, size_t size)
138	{	201	{
139	for (;;)	202	for (;;)
140	{	203	{
141	void *newptr = realloc (ptr, size);	204	void *newptr = realloc (ptr, size);
142		205
…		…
158	callback is set, then libev will expect it to remedy the sitution, no	221	callback is set, then libev will expect it to remedy the sitution, no
159	matter what, when it returns. That is, libev will generally retry the	222	matter what, when it returns. That is, libev will generally retry the
160	requested operation, or, if the condition doesn't go away, do bad stuff	223	requested operation, or, if the condition doesn't go away, do bad stuff
161	(such as abort).	224	(such as abort).
162		225
163	Example: do the same thing as libev does internally:	226	Example: This is basically the same thing that libev does internally, too.
164		227
165	static void	228	static void
166	fatal_error (const char *msg)	229	fatal_error (const char *msg)
167	{	230	{
168	perror (msg);	231	perror (msg);
…		…
218	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	281	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
219	override the flags completely if it is found in the environment. This is	282	override the flags completely if it is found in the environment. This is
220	useful to try out specific backends to test their performance, or to work	283	useful to try out specific backends to test their performance, or to work
221	around bugs.	284	around bugs.
222		285
		286	=item C<EVFLAG_FORKCHECK>
		287
		288	Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after
		289	a fork, you can also make libev check for a fork in each iteration by
		290	enabling this flag.
		291
		292	This works by calling C<getpid ()> on every iteration of the loop,
		293	and thus this might slow down your event loop if you do a lot of loop
		294	iterations and little real work, but is usually not noticeable (on my
		295	Linux system for example, C<getpid> is actually a simple 5-insn sequence
		296	without a syscall and thus I<very> fast, but my Linux system also has
		297	C<pthread_atfork> which is even faster).
		298
		299	The big advantage of this flag is that you can forget about fork (and
		300	forget about forgetting to tell libev about forking) when you use this
		301	flag.
		302
		303	This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS>
		304	environment variable.
		305
223	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	306	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
224		307
225	This is your standard select(2) backend. Not I<completely> standard, as	308	This is your standard select(2) backend. Not I<completely> standard, as
226	libev tries to roll its own fd_set with no limits on the number of fds,	309	libev tries to roll its own fd_set with no limits on the number of fds,
227	but if that fails, expect a fairly low limit on the number of fds when	310	but if that fails, expect a fairly low limit on the number of fds when
228	using this backend. It doesn't scale too well (O(highest_fd)), but its usually	311	using this backend. It doesn't scale too well (O(highest_fd)), but its
229	the fastest backend for a low number of fds.	312	usually the fastest backend for a low number of (low-numbered :) fds.
		313
		314	To get good performance out of this backend you need a high amount of
		315	parallelity (most of the file descriptors should be busy). If you are
		316	writing a server, you should C<accept ()> in a loop to accept as many
		317	connections as possible during one iteration. You might also want to have
		318	a look at C<ev_set_io_collect_interval ()> to increase the amount of
		319	readyness notifications you get per iteration.
230		320
231	=item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows)	321	=item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows)
232		322
233	And this is your standard poll(2) backend. It's more complicated than	323	And this is your standard poll(2) backend. It's more complicated
234	select, but handles sparse fds better and has no artificial limit on the	324	than select, but handles sparse fds better and has no artificial
235	number of fds you can use (except it will slow down considerably with a	325	limit on the number of fds you can use (except it will slow down
236	lot of inactive fds). It scales similarly to select, i.e. O(total_fds).	326	considerably with a lot of inactive fds). It scales similarly to select,
		327	i.e. O(total_fds). See the entry for C<EVBACKEND_SELECT>, above, for
		328	performance tips.
237		329
238	=item C<EVBACKEND_EPOLL> (value 4, Linux)	330	=item C<EVBACKEND_EPOLL> (value 4, Linux)
239		331
240	For few fds, this backend is a bit little slower than poll and select,	332	For few fds, this backend is a bit little slower than poll and select,
241	but it scales phenomenally better. While poll and select usually scale like	333	but it scales phenomenally better. While poll and select usually scale
242	O(total_fds) where n is the total number of fds (or the highest fd), epoll scales	334	like O(total_fds) where n is the total number of fds (or the highest fd),
243	either O(1) or O(active_fds).	335	epoll scales either O(1) or O(active_fds). The epoll design has a number
		336	of shortcomings, such as silently dropping events in some hard-to-detect
		337	cases and rewiring a syscall per fd change, no fork support and bad
		338	support for dup.
244		339
245	While stopping and starting an I/O watcher in the same iteration will	340	While stopping, setting and starting an I/O watcher in the same iteration
246	result in some caching, there is still a syscall per such incident	341	will result in some caching, there is still a syscall per such incident
247	(because the fd could point to a different file description now), so its	342	(because the fd could point to a different file description now), so its
248	best to avoid that. Also, dup()ed file descriptors might not work very	343	best to avoid that. Also, C<dup ()>'ed file descriptors might not work
249	well if you register events for both fds.	344	very well if you register events for both fds.
250		345
251	Please note that epoll sometimes generates spurious notifications, so you	346	Please note that epoll sometimes generates spurious notifications, so you
252	need to use non-blocking I/O or other means to avoid blocking when no data	347	need to use non-blocking I/O or other means to avoid blocking when no data
253	(or space) is available.	348	(or space) is available.
254		349
		350	Best performance from this backend is achieved by not unregistering all
		351	watchers for a file descriptor until it has been closed, if possible, i.e.
		352	keep at least one watcher active per fd at all times.
		353
		354	While nominally embeddeble in other event loops, this feature is broken in
		355	all kernel versions tested so far.
		356
255	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)	357	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)
256		358
257	Kqueue deserves special mention, as at the time of this writing, it	359	Kqueue deserves special mention, as at the time of this writing, it
258	was broken on all BSDs except NetBSD (usually it doesn't work with	360	was broken on all BSDs except NetBSD (usually it doesn't work reliably
259	anything but sockets and pipes, except on Darwin, where of course its	361	with anything but sockets and pipes, except on Darwin, where of course
260	completely useless). For this reason its not being "autodetected"	362	it's completely useless). For this reason it's not being "autodetected"
261	unless you explicitly specify it explicitly in the flags (i.e. using	363	unless you explicitly specify it explicitly in the flags (i.e. using
262	C<EVBACKEND_KQUEUE>).	364	C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough)
		365	system like NetBSD.
		366
		367	You still can embed kqueue into a normal poll or select backend and use it
		368	only for sockets (after having made sure that sockets work with kqueue on
		369	the target platform). See C<ev_embed> watchers for more info.
263		370
264	It scales in the same way as the epoll backend, but the interface to the	371	It scales in the same way as the epoll backend, but the interface to the
265	kernel is more efficient (which says nothing about its actual speed, of	372	kernel is more efficient (which says nothing about its actual speed, of
266	course). While starting and stopping an I/O watcher does not cause an	373	course). While stopping, setting and starting an I/O watcher does never
267	extra syscall as with epoll, it still adds up to four event changes per	374	cause an extra syscall as with C<EVBACKEND_EPOLL>, it still adds up to
268	incident, so its best to avoid that.	375	two event changes per incident, support for C<fork ()> is very bad and it
		376	drops fds silently in similarly hard-to-detect cases.
		377
		378	This backend usually performs well under most conditions.
		379
		380	While nominally embeddable in other event loops, this doesn't work
		381	everywhere, so you might need to test for this. And since it is broken
		382	almost everywhere, you should only use it when you have a lot of sockets
		383	(for which it usually works), by embedding it into another event loop
		384	(e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>) and using it only for
		385	sockets.
269		386
270	=item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8)	387	=item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8)
271		388
272	This is not implemented yet (and might never be).	389	This is not implemented yet (and might never be, unless you send me an
		390	implementation). According to reports, C</dev/poll> only supports sockets
		391	and is not embeddable, which would limit the usefulness of this backend
		392	immensely.
273		393
274	=item C<EVBACKEND_PORT> (value 32, Solaris 10)	394	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
275		395
276	This uses the Solaris 10 port mechanism. As with everything on Solaris,	396	This uses the Solaris 10 event port mechanism. As with everything on Solaris,
277	it's really slow, but it still scales very well (O(active_fds)).	397	it's really slow, but it still scales very well (O(active_fds)).
278		398
279	Please note that solaris ports can result in a lot of spurious	399	Please note that solaris event ports can deliver a lot of spurious
280	notifications, so you need to use non-blocking I/O or other means to avoid	400	notifications, so you need to use non-blocking I/O or other means to avoid
281	blocking when no data (or space) is available.	401	blocking when no data (or space) is available.
		402
		403	While this backend scales well, it requires one system call per active
		404	file descriptor per loop iteration. For small and medium numbers of file
		405	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend
		406	might perform better.
282		407
283	=item C<EVBACKEND_ALL>	408	=item C<EVBACKEND_ALL>
284		409
285	Try all backends (even potentially broken ones that wouldn't be tried	410	Try all backends (even potentially broken ones that wouldn't be tried
286	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as	411	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as
287	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.	412	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.
		413
		414	It is definitely not recommended to use this flag.
288		415
289	=back	416	=back
290		417
291	If one or more of these are ored into the flags value, then only these	418	If one or more of these are ored into the flags value, then only these
292	backends will be tried (in the reverse order as given here). If none are	419	backends will be tried (in the reverse order as given here). If none are
…		…
314	Similar to C<ev_default_loop>, but always creates a new event loop that is	441	Similar to C<ev_default_loop>, but always creates a new event loop that is
315	always distinct from the default loop. Unlike the default loop, it cannot	442	always distinct from the default loop. Unlike the default loop, it cannot
316	handle signal and child watchers, and attempts to do so will be greeted by	443	handle signal and child watchers, and attempts to do so will be greeted by
317	undefined behaviour (or a failed assertion if assertions are enabled).	444	undefined behaviour (or a failed assertion if assertions are enabled).
318		445
319	Example: try to create a event loop that uses epoll and nothing else.	446	Example: Try to create a event loop that uses epoll and nothing else.
320		447
321	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	448	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
322	if (!epoller)	449	if (!epoller)
323	fatal ("no epoll found here, maybe it hides under your chair");	450	fatal ("no epoll found here, maybe it hides under your chair");
324		451
…		…
327	Destroys the default loop again (frees all memory and kernel state	454	Destroys the default loop again (frees all memory and kernel state
328	etc.). None of the active event watchers will be stopped in the normal	455	etc.). None of the active event watchers will be stopped in the normal
329	sense, so e.g. C<ev_is_active> might still return true. It is your	456	sense, so e.g. C<ev_is_active> might still return true. It is your
330	responsibility to either stop all watchers cleanly yoursef I<before>	457	responsibility to either stop all watchers cleanly yoursef I<before>
331	calling this function, or cope with the fact afterwards (which is usually	458	calling this function, or cope with the fact afterwards (which is usually
332	the easiest thing, youc na just ignore the watchers and/or C<free ()> them	459	the easiest thing, you can just ignore the watchers and/or C<free ()> them
333	for example).	460	for example).
		461
		462	Note that certain global state, such as signal state, will not be freed by
		463	this function, and related watchers (such as signal and child watchers)
		464	would need to be stopped manually.
		465
		466	In general it is not advisable to call this function except in the
		467	rare occasion where you really need to free e.g. the signal handling
		468	pipe fds. If you need dynamically allocated loops it is better to use
		469	C<ev_loop_new> and C<ev_loop_destroy>).
334		470
335	=item ev_loop_destroy (loop)	471	=item ev_loop_destroy (loop)
336		472
337	Like C<ev_default_destroy>, but destroys an event loop created by an	473	Like C<ev_default_destroy>, but destroys an event loop created by an
338	earlier call to C<ev_loop_new>.	474	earlier call to C<ev_loop_new>.
…		…
362		498
363	Like C<ev_default_fork>, but acts on an event loop created by	499	Like C<ev_default_fork>, but acts on an event loop created by
364	C<ev_loop_new>. Yes, you have to call this on every allocated event loop	500	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
365	after fork, and how you do this is entirely your own problem.	501	after fork, and how you do this is entirely your own problem.
366		502
		503	=item unsigned int ev_loop_count (loop)
		504
		505	Returns the count of loop iterations for the loop, which is identical to
		506	the number of times libev did poll for new events. It starts at C<0> and
		507	happily wraps around with enough iterations.
		508
		509	This value can sometimes be useful as a generation counter of sorts (it
		510	"ticks" the number of loop iterations), as it roughly corresponds with
		511	C<ev_prepare> and C<ev_check> calls.
		512
367	=item unsigned int ev_backend (loop)	513	=item unsigned int ev_backend (loop)
368		514
369	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	515	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
370	use.	516	use.
371		517
…		…
373		519
374	Returns the current "event loop time", which is the time the event loop	520	Returns the current "event loop time", which is the time the event loop
375	received events and started processing them. This timestamp does not	521	received events and started processing them. This timestamp does not
376	change as long as callbacks are being processed, and this is also the base	522	change as long as callbacks are being processed, and this is also the base
377	time used for relative timers. You can treat it as the timestamp of the	523	time used for relative timers. You can treat it as the timestamp of the
378	event occuring (or more correctly, libev finding out about it).	524	event occurring (or more correctly, libev finding out about it).
379		525
380	=item ev_loop (loop, int flags)	526	=item ev_loop (loop, int flags)
381		527
382	Finally, this is it, the event handler. This function usually is called	528	Finally, this is it, the event handler. This function usually is called
383	after you initialised all your watchers and you want to start handling	529	after you initialised all your watchers and you want to start handling
…		…
404	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is	550	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is
405	usually a better approach for this kind of thing.	551	usually a better approach for this kind of thing.
406		552
407	Here are the gory details of what C<ev_loop> does:	553	Here are the gory details of what C<ev_loop> does:
408		554
		555	- Before the first iteration, call any pending watchers.
409	* If there are no active watchers (reference count is zero), return.	556	* If there are no active watchers (reference count is zero), return.
410	- Queue prepare watchers and then call all outstanding watchers.	557	- Queue all prepare watchers and then call all outstanding watchers.
411	- If we have been forked, recreate the kernel state.	558	- If we have been forked, recreate the kernel state.
412	- Update the kernel state with all outstanding changes.	559	- Update the kernel state with all outstanding changes.
413	- Update the "event loop time".	560	- Update the "event loop time".
414	- Calculate for how long to block.	561	- Calculate for how long to block.
415	- Block the process, waiting for any events.	562	- Block the process, waiting for any events.
…		…
423	Signals and child watchers are implemented as I/O watchers, and will	570	Signals and child watchers are implemented as I/O watchers, and will
424	be handled here by queueing them when their watcher gets executed.	571	be handled here by queueing them when their watcher gets executed.
425	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	572	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
426	were used, return, otherwise continue with step *.	573	were used, return, otherwise continue with step *.
427		574
428	Example: queue some jobs and then loop until no events are outsanding	575	Example: Queue some jobs and then loop until no events are outsanding
429	anymore.	576	anymore.
430		577
431	... queue jobs here, make sure they register event watchers as long	578	... queue jobs here, make sure they register event watchers as long
432	... as they still have work to do (even an idle watcher will do..)	579	... as they still have work to do (even an idle watcher will do..)
433	ev_loop (my_loop, 0);	580	ev_loop (my_loop, 0);
…		…
453	visible to the libev user and should not keep C<ev_loop> from exiting if	600	visible to the libev user and should not keep C<ev_loop> from exiting if
454	no event watchers registered by it are active. It is also an excellent	601	no event watchers registered by it are active. It is also an excellent
455	way to do this for generic recurring timers or from within third-party	602	way to do this for generic recurring timers or from within third-party
456	libraries. Just remember to I<unref after start> and I<ref before stop>.	603	libraries. Just remember to I<unref after start> and I<ref before stop>.
457		604
458	Example: create a signal watcher, but keep it from keeping C<ev_loop>	605	Example: Create a signal watcher, but keep it from keeping C<ev_loop>
459	running when nothing else is active.	606	running when nothing else is active.
460		607
461	struct dv_signal exitsig;	608	struct ev_signal exitsig;
462	ev_signal_init (&exitsig, sig_cb, SIGINT);	609	ev_signal_init (&exitsig, sig_cb, SIGINT);
463	ev_signal_start (myloop, &exitsig);	610	ev_signal_start (loop, &exitsig);
464	evf_unref (myloop);	611	evf_unref (loop);
465		612
466	Example: for some weird reason, unregister the above signal handler again.	613	Example: For some weird reason, unregister the above signal handler again.
467		614
468	ev_ref (myloop);	615	ev_ref (loop);
469	ev_signal_stop (myloop, &exitsig);	616	ev_signal_stop (loop, &exitsig);
		617
		618	=item ev_set_io_collect_interval (loop, ev_tstamp interval)
		619
		620	=item ev_set_timeout_collect_interval (loop, ev_tstamp interval)
		621
		622	These advanced functions influence the time that libev will spend waiting
		623	for events. Both are by default C<0>, meaning that libev will try to
		624	invoke timer/periodic callbacks and I/O callbacks with minimum latency.
		625
		626	Setting these to a higher value (the C<interval> I<must> be >= C<0>)
		627	allows libev to delay invocation of I/O and timer/periodic callbacks to
		628	increase efficiency of loop iterations.
		629
		630	The background is that sometimes your program runs just fast enough to
		631	handle one (or very few) event(s) per loop iteration. While this makes
		632	the program responsive, it also wastes a lot of CPU time to poll for new
		633	events, especially with backends like C<select ()> which have a high
		634	overhead for the actual polling but can deliver many events at once.
		635
		636	By setting a higher I<io collect interval> you allow libev to spend more
		637	time collecting I/O events, so you can handle more events per iteration,
		638	at the cost of increasing latency. Timeouts (both C<ev_periodic> and
		639	C<ev_timer>) will be not affected. Setting this to a non-null value will
		640	introduce an additional C<ev_sleep ()> call into most loop iterations.
		641
		642	Likewise, by setting a higher I<timeout collect interval> you allow libev
		643	to spend more time collecting timeouts, at the expense of increased
		644	latency (the watcher callback will be called later). C<ev_io> watchers
		645	will not be affected. Setting this to a non-null value will not introduce
		646	any overhead in libev.
		647
		648	Many (busy) programs can usually benefit by setting the io collect
		649	interval to a value near C<0.1> or so, which is often enough for
		650	interactive servers (of course not for games), likewise for timeouts. It
		651	usually doesn't make much sense to set it to a lower value than C<0.01>,
		652	as this approsaches the timing granularity of most systems.
470		653
471	=back	654	=back
		655
472		656
473	=head1 ANATOMY OF A WATCHER	657	=head1 ANATOMY OF A WATCHER
474		658
475	A watcher is a structure that you create and register to record your	659	A watcher is a structure that you create and register to record your
476	interest in some event. For instance, if you want to wait for STDIN to	660	interest in some event. For instance, if you want to wait for STDIN to
…		…
543	The signal specified in the C<ev_signal> watcher has been received by a thread.	727	The signal specified in the C<ev_signal> watcher has been received by a thread.
544		728
545	=item C<EV_CHILD>	729	=item C<EV_CHILD>
546		730
547	The pid specified in the C<ev_child> watcher has received a status change.	731	The pid specified in the C<ev_child> watcher has received a status change.
		732
		733	=item C<EV_STAT>
		734
		735	The path specified in the C<ev_stat> watcher changed its attributes somehow.
548		736
549	=item C<EV_IDLE>	737	=item C<EV_IDLE>
550		738
551	The C<ev_idle> watcher has determined that you have nothing better to do.	739	The C<ev_idle> watcher has determined that you have nothing better to do.
552		740
…		…
560	received events. Callbacks of both watcher types can start and stop as	748	received events. Callbacks of both watcher types can start and stop as
561	many watchers as they want, and all of them will be taken into account	749	many watchers as they want, and all of them will be taken into account
562	(for example, a C<ev_prepare> watcher might start an idle watcher to keep	750	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
563	C<ev_loop> from blocking).	751	C<ev_loop> from blocking).
564		752
		753	=item C<EV_EMBED>
		754
		755	The embedded event loop specified in the C<ev_embed> watcher needs attention.
		756
		757	=item C<EV_FORK>
		758
		759	The event loop has been resumed in the child process after fork (see
		760	C<ev_fork>).
		761
565	=item C<EV_ERROR>	762	=item C<EV_ERROR>
566		763
567	An unspecified error has occured, the watcher has been stopped. This might	764	An unspecified error has occured, the watcher has been stopped. This might
568	happen because the watcher could not be properly started because libev	765	happen because the watcher could not be properly started because libev
569	ran out of memory, a file descriptor was found to be closed or any other	766	ran out of memory, a file descriptor was found to be closed or any other
…		…
576	with the error from read() or write(). This will not work in multithreaded	773	with the error from read() or write(). This will not work in multithreaded
577	programs, though, so beware.	774	programs, though, so beware.
578		775
579	=back	776	=back
580		777
581	=head2 SUMMARY OF GENERIC WATCHER FUNCTIONS	778	=head2 GENERIC WATCHER FUNCTIONS
582		779
583	In the following description, C<TYPE> stands for the watcher type,	780	In the following description, C<TYPE> stands for the watcher type,
584	e.g. C<timer> for C<ev_timer> watchers and C<io> for C<ev_io> watchers.	781	e.g. C<timer> for C<ev_timer> watchers and C<io> for C<ev_io> watchers.
585		782
586	=over 4	783	=over 4
…		…
595	which rolls both calls into one.	792	which rolls both calls into one.
596		793
597	You can reinitialise a watcher at any time as long as it has been stopped	794	You can reinitialise a watcher at any time as long as it has been stopped
598	(or never started) and there are no pending events outstanding.	795	(or never started) and there are no pending events outstanding.
599		796
600	The callbakc is always of type C<void (*)(ev_loop *loop, ev_TYPE *watcher,	797	The callback is always of type C<void (*)(ev_loop *loop, ev_TYPE *watcher,
601	int revents)>.	798	int revents)>.
602		799
603	=item C<ev_TYPE_set> (ev_TYPE *, [args])	800	=item C<ev_TYPE_set> (ev_TYPE *, [args])
604		801
605	This macro initialises the type-specific parts of a watcher. You need to	802	This macro initialises the type-specific parts of a watcher. You need to
…		…
640	=item bool ev_is_pending (ev_TYPE *watcher)	837	=item bool ev_is_pending (ev_TYPE *watcher)
641		838
642	Returns a true value iff the watcher is pending, (i.e. it has outstanding	839	Returns a true value iff the watcher is pending, (i.e. it has outstanding
643	events but its callback has not yet been invoked). As long as a watcher	840	events but its callback has not yet been invoked). As long as a watcher
644	is pending (but not active) you must not call an init function on it (but	841	is pending (but not active) you must not call an init function on it (but
645	C<ev_TYPE_set> is safe) and you must make sure the watcher is available to	842	C<ev_TYPE_set> is safe), you must not change its priority, and you must
646	libev (e.g. you cnanot C<free ()> it).	843	make sure the watcher is available to libev (e.g. you cannot C<free ()>
		844	it).
647		845
648	=item callback = ev_cb (ev_TYPE *watcher)	846	=item callback ev_cb (ev_TYPE *watcher)
649		847
650	Returns the callback currently set on the watcher.	848	Returns the callback currently set on the watcher.
651		849
652	=item ev_cb_set (ev_TYPE *watcher, callback)	850	=item ev_cb_set (ev_TYPE *watcher, callback)
653		851
654	Change the callback. You can change the callback at virtually any time	852	Change the callback. You can change the callback at virtually any time
655	(modulo threads).	853	(modulo threads).
		854
		855	=item ev_set_priority (ev_TYPE *watcher, priority)
		856
		857	=item int ev_priority (ev_TYPE *watcher)
		858
		859	Set and query the priority of the watcher. The priority is a small
		860	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>
		861	(default: C<-2>). Pending watchers with higher priority will be invoked
		862	before watchers with lower priority, but priority will not keep watchers
		863	from being executed (except for C<ev_idle> watchers).
		864
		865	This means that priorities are I<only> used for ordering callback
		866	invocation after new events have been received. This is useful, for
		867	example, to reduce latency after idling, or more often, to bind two
		868	watchers on the same event and make sure one is called first.
		869
		870	If you need to suppress invocation when higher priority events are pending
		871	you need to look at C<ev_idle> watchers, which provide this functionality.
		872
		873	You I<must not> change the priority of a watcher as long as it is active or
		874	pending.
		875
		876	The default priority used by watchers when no priority has been set is
		877	always C<0>, which is supposed to not be too high and not be too low :).
		878
		879	Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is
		880	fine, as long as you do not mind that the priority value you query might
		881	or might not have been adjusted to be within valid range.
		882
		883	=item ev_invoke (loop, ev_TYPE *watcher, int revents)
		884
		885	Invoke the C<watcher> with the given C<loop> and C<revents>. Neither
		886	C<loop> nor C<revents> need to be valid as long as the watcher callback
		887	can deal with that fact.
		888
		889	=item int ev_clear_pending (loop, ev_TYPE *watcher)
		890
		891	If the watcher is pending, this function returns clears its pending status
		892	and returns its C<revents> bitset (as if its callback was invoked). If the
		893	watcher isn't pending it does nothing and returns C<0>.
656		894
657	=back	895	=back
658		896
659		897
660	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	898	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
681	{	919	{
682	struct my_io *w = (struct my_io *)w_;	920	struct my_io *w = (struct my_io *)w_;
683	...	921	...
684	}	922	}
685		923
686	More interesting and less C-conformant ways of catsing your callback type	924	More interesting and less C-conformant ways of casting your callback type
687	have been omitted....	925	instead have been omitted.
		926
		927	Another common scenario is having some data structure with multiple
		928	watchers:
		929
		930	struct my_biggy
		931	{
		932	int some_data;
		933	ev_timer t1;
		934	ev_timer t2;
		935	}
		936
		937	In this case getting the pointer to C<my_biggy> is a bit more complicated,
		938	you need to use C<offsetof>:
		939
		940	#include <stddef.h>
		941
		942	static void
		943	t1_cb (EV_P_ struct ev_timer *w, int revents)
		944	{
		945	struct my_biggy big = (struct my_biggy *
		946	(((char *)w) - offsetof (struct my_biggy, t1));
		947	}
		948
		949	static void
		950	t2_cb (EV_P_ struct ev_timer *w, int revents)
		951	{
		952	struct my_biggy big = (struct my_biggy *
		953	(((char *)w) - offsetof (struct my_biggy, t2));
		954	}
688		955
689		956
690	=head1 WATCHER TYPES	957	=head1 WATCHER TYPES
691		958
692	This section describes each watcher in detail, but will not repeat	959	This section describes each watcher in detail, but will not repeat
693	information given in the last section.	960	information given in the last section. Any initialisation/set macros,
		961	functions and members specific to the watcher type are explained.
694		962
		963	Members are additionally marked with either I<[read-only]>, meaning that,
		964	while the watcher is active, you can look at the member and expect some
		965	sensible content, but you must not modify it (you can modify it while the
		966	watcher is stopped to your hearts content), or I<[read-write]>, which
		967	means you can expect it to have some sensible content while the watcher
		968	is active, but you can also modify it. Modifying it may not do something
		969	sensible or take immediate effect (or do anything at all), but libev will
		970	not crash or malfunction in any way.
695		971
		972
696	=head2 C<ev_io> - is this file descriptor readable or writable	973	=head2 C<ev_io> - is this file descriptor readable or writable?
697		974
698	I/O watchers check whether a file descriptor is readable or writable	975	I/O watchers check whether a file descriptor is readable or writable
699	in each iteration of the event loop (This behaviour is called	976	in each iteration of the event loop, or, more precisely, when reading
700	level-triggering because you keep receiving events as long as the	977	would not block the process and writing would at least be able to write
701	condition persists. Remember you can stop the watcher if you don't want to	978	some data. This behaviour is called level-triggering because you keep
702	act on the event and neither want to receive future events).	979	receiving events as long as the condition persists. Remember you can stop
		980	the watcher if you don't want to act on the event and neither want to
		981	receive future events.
703		982
704	In general you can register as many read and/or write event watchers per	983	In general you can register as many read and/or write event watchers per
705	fd as you want (as long as you don't confuse yourself). Setting all file	984	fd as you want (as long as you don't confuse yourself). Setting all file
706	descriptors to non-blocking mode is also usually a good idea (but not	985	descriptors to non-blocking mode is also usually a good idea (but not
707	required if you know what you are doing).	986	required if you know what you are doing).
708		987
709	You have to be careful with dup'ed file descriptors, though. Some backends	988	You have to be careful with dup'ed file descriptors, though. Some backends
710	(the linux epoll backend is a notable example) cannot handle dup'ed file	989	(the linux epoll backend is a notable example) cannot handle dup'ed file
711	descriptors correctly if you register interest in two or more fds pointing	990	descriptors correctly if you register interest in two or more fds pointing
712	to the same underlying file/socket etc. description (that is, they share	991	to the same underlying file/socket/etc. description (that is, they share
713	the same underlying "file open").	992	the same underlying "file open").
714		993
715	If you must do this, then force the use of a known-to-be-good backend	994	If you must do this, then force the use of a known-to-be-good backend
716	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and	995	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and
717	C<EVBACKEND_POLL>).	996	C<EVBACKEND_POLL>).
718		997
		998	Another thing you have to watch out for is that it is quite easy to
		999	receive "spurious" readyness notifications, that is your callback might
		1000	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
		1001	because there is no data. Not only are some backends known to create a
		1002	lot of those (for example solaris ports), it is very easy to get into
		1003	this situation even with a relatively standard program structure. Thus
		1004	it is best to always use non-blocking I/O: An extra C<read>(2) returning
		1005	C<EAGAIN> is far preferable to a program hanging until some data arrives.
		1006
		1007	If you cannot run the fd in non-blocking mode (for example you should not
		1008	play around with an Xlib connection), then you have to seperately re-test
		1009	whether a file descriptor is really ready with a known-to-be good interface
		1010	such as poll (fortunately in our Xlib example, Xlib already does this on
		1011	its own, so its quite safe to use).
		1012
		1013	=head3 The special problem of disappearing file descriptors
		1014
		1015	Some backends (e.g. kqueue, epoll) need to be told about closing a file
		1016	descriptor (either by calling C<close> explicitly or by any other means,
		1017	such as C<dup>). The reason is that you register interest in some file
		1018	descriptor, but when it goes away, the operating system will silently drop
		1019	this interest. If another file descriptor with the same number then is
		1020	registered with libev, there is no efficient way to see that this is, in
		1021	fact, a different file descriptor.
		1022
		1023	To avoid having to explicitly tell libev about such cases, libev follows
		1024	the following policy: Each time C<ev_io_set> is being called, libev
		1025	will assume that this is potentially a new file descriptor, otherwise
		1026	it is assumed that the file descriptor stays the same. That means that
		1027	you I<have> to call C<ev_io_set> (or C<ev_io_init>) when you change the
		1028	descriptor even if the file descriptor number itself did not change.
		1029
		1030	This is how one would do it normally anyway, the important point is that
		1031	the libev application should not optimise around libev but should leave
		1032	optimisations to libev.
		1033
		1034	=head3 The special problem of dup'ed file descriptors
		1035
		1036	Some backends (e.g. epoll), cannot register events for file descriptors,
		1037	but only events for the underlying file descriptions. That means when you
		1038	have C<dup ()>'ed file descriptors and register events for them, only one
		1039	file descriptor might actually receive events.
		1040
		1041	There is no workaround possible except not registering events
		1042	for potentially C<dup ()>'ed file descriptors, or to resort to
		1043	C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>.
		1044
		1045	=head3 The special problem of fork
		1046
		1047	Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit
		1048	useless behaviour. Libev fully supports fork, but needs to be told about
		1049	it in the child.
		1050
		1051	To support fork in your programs, you either have to call
		1052	C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child,
		1053	enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or
		1054	C<EVBACKEND_POLL>.
		1055
		1056
		1057	=head3 Watcher-Specific Functions
		1058
719	=over 4	1059	=over 4
720		1060
721	=item ev_io_init (ev_io *, callback, int fd, int events)	1061	=item ev_io_init (ev_io *, callback, int fd, int events)
722		1062
723	=item ev_io_set (ev_io *, int fd, int events)	1063	=item ev_io_set (ev_io *, int fd, int events)
724		1064
725	Configures an C<ev_io> watcher. The fd is the file descriptor to rceeive	1065	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to
726	events for and events is either C<EV_READ>, C<EV_WRITE> or C<EV_READ |	1066	rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or
727	EV_WRITE> to receive the given events.	1067	C<EV_READ | EV_WRITE> to receive the given events.
728		1068
729	Please note that most of the more scalable backend mechanisms (for example	1069	=item int fd [read-only]
730	epoll and solaris ports) can result in spurious readyness notifications	1070
731	for file descriptors, so you practically need to use non-blocking I/O (and	1071	The file descriptor being watched.
732	treat callback invocation as hint only), or retest separately with a safe	1072
733	interface before doing I/O (XLib can do this), or force the use of either	1073	=item int events [read-only]
734	C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>, which don't suffer from this	1074
735	problem. Also note that it is quite easy to have your callback invoked	1075	The events being watched.
736	when the readyness condition is no longer valid even when employing
737	typical ways of handling events, so its a good idea to use non-blocking
738	I/O unconditionally.
739		1076
740	=back	1077	=back
741		1078
742	Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well	1079	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well
743	readable, but only once. Since it is likely line-buffered, you could	1080	readable, but only once. Since it is likely line-buffered, you could
744	attempt to read a whole line in the callback:	1081	attempt to read a whole line in the callback.
745		1082
746	static void	1083	static void
747	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1084	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
748	{	1085	{
749	ev_io_stop (loop, w);	1086	ev_io_stop (loop, w);
…		…
756	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1093	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
757	ev_io_start (loop, &stdin_readable);	1094	ev_io_start (loop, &stdin_readable);
758	ev_loop (loop, 0);	1095	ev_loop (loop, 0);
759		1096
760		1097
761	=head2 C<ev_timer> - relative and optionally recurring timeouts	1098	=head2 C<ev_timer> - relative and optionally repeating timeouts
762		1099
763	Timer watchers are simple relative timers that generate an event after a	1100	Timer watchers are simple relative timers that generate an event after a
764	given time, and optionally repeating in regular intervals after that.	1101	given time, and optionally repeating in regular intervals after that.
765		1102
766	The timers are based on real time, that is, if you register an event that	1103	The timers are based on real time, that is, if you register an event that
…		…
779		1116
780	The callback is guarenteed to be invoked only when its timeout has passed,	1117	The callback is guarenteed to be invoked only when its timeout has passed,
781	but if multiple timers become ready during the same loop iteration then	1118	but if multiple timers become ready during the same loop iteration then
782	order of execution is undefined.	1119	order of execution is undefined.
783		1120
		1121	=head3 Watcher-Specific Functions and Data Members
		1122
784	=over 4	1123	=over 4
785		1124
786	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	1125	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
787		1126
788	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)	1127	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)
…		…
801	=item ev_timer_again (loop)	1140	=item ev_timer_again (loop)
802		1141
803	This will act as if the timer timed out and restart it again if it is	1142	This will act as if the timer timed out and restart it again if it is
804	repeating. The exact semantics are:	1143	repeating. The exact semantics are:
805		1144
		1145	If the timer is pending, its pending status is cleared.
		1146
806	If the timer is started but nonrepeating, stop it.	1147	If the timer is started but nonrepeating, stop it (as if it timed out).
807		1148
808	If the timer is repeating, either start it if necessary (with the repeat	1149	If the timer is repeating, either start it if necessary (with the
809	value), or reset the running timer to the repeat value.	1150	C<repeat> value), or reset the running timer to the C<repeat> value.
810		1151
811	This sounds a bit complicated, but here is a useful and typical	1152	This sounds a bit complicated, but here is a useful and typical
812	example: Imagine you have a tcp connection and you want a so-called idle	1153	example: Imagine you have a tcp connection and you want a so-called idle
813	timeout, that is, you want to be called when there have been, say, 60	1154	timeout, that is, you want to be called when there have been, say, 60
814	seconds of inactivity on the socket. The easiest way to do this is to	1155	seconds of inactivity on the socket. The easiest way to do this is to
815	configure an C<ev_timer> with after=repeat=60 and calling ev_timer_again each	1156	configure an C<ev_timer> with a C<repeat> value of C<60> and then call
816	time you successfully read or write some data. If you go into an idle	1157	C<ev_timer_again> each time you successfully read or write some data. If
817	state where you do not expect data to travel on the socket, you can stop	1158	you go into an idle state where you do not expect data to travel on the
818	the timer, and again will automatically restart it if need be.	1159	socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will
		1160	automatically restart it if need be.
		1161
		1162	That means you can ignore the C<after> value and C<ev_timer_start>
		1163	altogether and only ever use the C<repeat> value and C<ev_timer_again>:
		1164
		1165	ev_timer_init (timer, callback, 0., 5.);
		1166	ev_timer_again (loop, timer);
		1167	...
		1168	timer->again = 17.;
		1169	ev_timer_again (loop, timer);
		1170	...
		1171	timer->again = 10.;
		1172	ev_timer_again (loop, timer);
		1173
		1174	This is more slightly efficient then stopping/starting the timer each time
		1175	you want to modify its timeout value.
		1176
		1177	=item ev_tstamp repeat [read-write]
		1178
		1179	The current C<repeat> value. Will be used each time the watcher times out
		1180	or C<ev_timer_again> is called and determines the next timeout (if any),
		1181	which is also when any modifications are taken into account.
819		1182
820	=back	1183	=back
821		1184
822	Example: create a timer that fires after 60 seconds.	1185	Example: Create a timer that fires after 60 seconds.
823		1186
824	static void	1187	static void
825	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1188	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
826	{	1189	{
827	.. one minute over, w is actually stopped right here	1190	.. one minute over, w is actually stopped right here
…		…
829		1192
830	struct ev_timer mytimer;	1193	struct ev_timer mytimer;
831	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1194	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
832	ev_timer_start (loop, &mytimer);	1195	ev_timer_start (loop, &mytimer);
833		1196
834	Example: create a timeout timer that times out after 10 seconds of	1197	Example: Create a timeout timer that times out after 10 seconds of
835	inactivity.	1198	inactivity.
836		1199
837	static void	1200	static void
838	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1201	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
839	{	1202	{
…		…
848	// and in some piece of code that gets executed on any "activity":	1211	// and in some piece of code that gets executed on any "activity":
849	// reset the timeout to start ticking again at 10 seconds	1212	// reset the timeout to start ticking again at 10 seconds
850	ev_timer_again (&mytimer);	1213	ev_timer_again (&mytimer);
851		1214
852		1215
853	=head2 C<ev_periodic> - to cron or not to cron	1216	=head2 C<ev_periodic> - to cron or not to cron?
854		1217
855	Periodic watchers are also timers of a kind, but they are very versatile	1218	Periodic watchers are also timers of a kind, but they are very versatile
856	(and unfortunately a bit complex).	1219	(and unfortunately a bit complex).
857		1220
858	Unlike C<ev_timer>'s, they are not based on real time (or relative time)	1221	Unlike C<ev_timer>'s, they are not based on real time (or relative time)
859	but on wallclock time (absolute time). You can tell a periodic watcher	1222	but on wallclock time (absolute time). You can tell a periodic watcher
860	to trigger "at" some specific point in time. For example, if you tell a	1223	to trigger "at" some specific point in time. For example, if you tell a
861	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()	1224	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()
862	+ 10.>) and then reset your system clock to the last year, then it will	1225	+ 10.>) and then reset your system clock to the last year, then it will
863	take a year to trigger the event (unlike an C<ev_timer>, which would trigger	1226	take a year to trigger the event (unlike an C<ev_timer>, which would trigger
864	roughly 10 seconds later and of course not if you reset your system time	1227	roughly 10 seconds later).
865	again).
866		1228
867	They can also be used to implement vastly more complex timers, such as	1229	They can also be used to implement vastly more complex timers, such as
868	triggering an event on eahc midnight, local time.	1230	triggering an event on each midnight, local time or other, complicated,
		1231	rules.
869		1232
870	As with timers, the callback is guarenteed to be invoked only when the	1233	As with timers, the callback is guarenteed to be invoked only when the
871	time (C<at>) has been passed, but if multiple periodic timers become ready	1234	time (C<at>) has been passed, but if multiple periodic timers become ready
872	during the same loop iteration then order of execution is undefined.	1235	during the same loop iteration then order of execution is undefined.
873		1236
		1237	=head3 Watcher-Specific Functions and Data Members
		1238
874	=over 4	1239	=over 4
875		1240
876	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)	1241	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)
877		1242
878	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)	1243	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)
…		…
880	Lots of arguments, lets sort it out... There are basically three modes of	1245	Lots of arguments, lets sort it out... There are basically three modes of
881	operation, and we will explain them from simplest to complex:	1246	operation, and we will explain them from simplest to complex:
882		1247
883	=over 4	1248	=over 4
884		1249
885	=item * absolute timer (interval = reschedule_cb = 0)	1250	=item * absolute timer (at = time, interval = reschedule_cb = 0)
886		1251
887	In this configuration the watcher triggers an event at the wallclock time	1252	In this configuration the watcher triggers an event at the wallclock time
888	C<at> and doesn't repeat. It will not adjust when a time jump occurs,	1253	C<at> and doesn't repeat. It will not adjust when a time jump occurs,
889	that is, if it is to be run at January 1st 2011 then it will run when the	1254	that is, if it is to be run at January 1st 2011 then it will run when the
890	system time reaches or surpasses this time.	1255	system time reaches or surpasses this time.
891		1256
892	=item * non-repeating interval timer (interval > 0, reschedule_cb = 0)	1257	=item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
893		1258
894	In this mode the watcher will always be scheduled to time out at the next	1259	In this mode the watcher will always be scheduled to time out at the next
895	C<at + N * interval> time (for some integer N) and then repeat, regardless	1260	C<at + N * interval> time (for some integer N, which can also be negative)
896	of any time jumps.	1261	and then repeat, regardless of any time jumps.
897		1262
898	This can be used to create timers that do not drift with respect to system	1263	This can be used to create timers that do not drift with respect to system
899	time:	1264	time:
900		1265
901	ev_periodic_set (&periodic, 0., 3600., 0);	1266	ev_periodic_set (&periodic, 0., 3600., 0);
…		…
907		1272
908	Another way to think about it (for the mathematically inclined) is that	1273	Another way to think about it (for the mathematically inclined) is that
909	C<ev_periodic> will try to run the callback in this mode at the next possible	1274	C<ev_periodic> will try to run the callback in this mode at the next possible
910	time where C<time = at (mod interval)>, regardless of any time jumps.	1275	time where C<time = at (mod interval)>, regardless of any time jumps.
911		1276
		1277	For numerical stability it is preferable that the C<at> value is near
		1278	C<ev_now ()> (the current time), but there is no range requirement for
		1279	this value.
		1280
912	=item * manual reschedule mode (reschedule_cb = callback)	1281	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
913		1282
914	In this mode the values for C<interval> and C<at> are both being	1283	In this mode the values for C<interval> and C<at> are both being
915	ignored. Instead, each time the periodic watcher gets scheduled, the	1284	ignored. Instead, each time the periodic watcher gets scheduled, the
916	reschedule callback will be called with the watcher as first, and the	1285	reschedule callback will be called with the watcher as first, and the
917	current time as second argument.	1286	current time as second argument.
918		1287
919	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,	1288	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,
920	ever, or make any event loop modifications>. If you need to stop it,	1289	ever, or make any event loop modifications>. If you need to stop it,
921	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by	1290	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by
922	starting a prepare watcher).	1291	starting an C<ev_prepare> watcher, which is legal).
923		1292
924	Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w,	1293	Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w,
925	ev_tstamp now)>, e.g.:	1294	ev_tstamp now)>, e.g.:
926		1295
927	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	1296	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
…		…
950	Simply stops and restarts the periodic watcher again. This is only useful	1319	Simply stops and restarts the periodic watcher again. This is only useful
951	when you changed some parameters or the reschedule callback would return	1320	when you changed some parameters or the reschedule callback would return
952	a different time than the last time it was called (e.g. in a crond like	1321	a different time than the last time it was called (e.g. in a crond like
953	program when the crontabs have changed).	1322	program when the crontabs have changed).
954		1323
		1324	=item ev_tstamp offset [read-write]
		1325
		1326	When repeating, this contains the offset value, otherwise this is the
		1327	absolute point in time (the C<at> value passed to C<ev_periodic_set>).
		1328
		1329	Can be modified any time, but changes only take effect when the periodic
		1330	timer fires or C<ev_periodic_again> is being called.
		1331
		1332	=item ev_tstamp interval [read-write]
		1333
		1334	The current interval value. Can be modified any time, but changes only
		1335	take effect when the periodic timer fires or C<ev_periodic_again> is being
		1336	called.
		1337
		1338	=item ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]
		1339
		1340	The current reschedule callback, or C<0>, if this functionality is
		1341	switched off. Can be changed any time, but changes only take effect when
		1342	the periodic timer fires or C<ev_periodic_again> is being called.
		1343
		1344	=item ev_tstamp at [read-only]
		1345
		1346	When active, contains the absolute time that the watcher is supposed to
		1347	trigger next.
		1348
955	=back	1349	=back
956		1350
957	Example: call a callback every hour, or, more precisely, whenever the	1351	Example: Call a callback every hour, or, more precisely, whenever the
958	system clock is divisible by 3600. The callback invocation times have	1352	system clock is divisible by 3600. The callback invocation times have
959	potentially a lot of jittering, but good long-term stability.	1353	potentially a lot of jittering, but good long-term stability.
960		1354
961	static void	1355	static void
962	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1356	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)
…		…
966		1360
967	struct ev_periodic hourly_tick;	1361	struct ev_periodic hourly_tick;
968	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1362	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
969	ev_periodic_start (loop, &hourly_tick);	1363	ev_periodic_start (loop, &hourly_tick);
970		1364
971	Example: the same as above, but use a reschedule callback to do it:	1365	Example: The same as above, but use a reschedule callback to do it:
972		1366
973	#include <math.h>	1367	#include <math.h>
974		1368
975	static ev_tstamp	1369	static ev_tstamp
976	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1370	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
…		…
978	return fmod (now, 3600.) + 3600.;	1372	return fmod (now, 3600.) + 3600.;
979	}	1373	}
980		1374
981	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1375	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
982		1376
983	Example: call a callback every hour, starting now:	1377	Example: Call a callback every hour, starting now:
984		1378
985	struct ev_periodic hourly_tick;	1379	struct ev_periodic hourly_tick;
986	ev_periodic_init (&hourly_tick, clock_cb,	1380	ev_periodic_init (&hourly_tick, clock_cb,
987	fmod (ev_now (loop), 3600.), 3600., 0);	1381	fmod (ev_now (loop), 3600.), 3600., 0);
988	ev_periodic_start (loop, &hourly_tick);	1382	ev_periodic_start (loop, &hourly_tick);
989		1383
990		1384
991	=head2 C<ev_signal> - signal me when a signal gets signalled	1385	=head2 C<ev_signal> - signal me when a signal gets signalled!
992		1386
993	Signal watchers will trigger an event when the process receives a specific	1387	Signal watchers will trigger an event when the process receives a specific
994	signal one or more times. Even though signals are very asynchronous, libev	1388	signal one or more times. Even though signals are very asynchronous, libev
995	will try it's best to deliver signals synchronously, i.e. as part of the	1389	will try it's best to deliver signals synchronously, i.e. as part of the
996	normal event processing, like any other event.	1390	normal event processing, like any other event.
…		…
1000	with the kernel (thus it coexists with your own signal handlers as long	1394	with the kernel (thus it coexists with your own signal handlers as long
1001	as you don't register any with libev). Similarly, when the last signal	1395	as you don't register any with libev). Similarly, when the last signal
1002	watcher for a signal is stopped libev will reset the signal handler to	1396	watcher for a signal is stopped libev will reset the signal handler to
1003	SIG_DFL (regardless of what it was set to before).	1397	SIG_DFL (regardless of what it was set to before).
1004		1398
		1399	=head3 Watcher-Specific Functions and Data Members
		1400
1005	=over 4	1401	=over 4
1006		1402
1007	=item ev_signal_init (ev_signal *, callback, int signum)	1403	=item ev_signal_init (ev_signal *, callback, int signum)
1008		1404
1009	=item ev_signal_set (ev_signal *, int signum)	1405	=item ev_signal_set (ev_signal *, int signum)
1010		1406
1011	Configures the watcher to trigger on the given signal number (usually one	1407	Configures the watcher to trigger on the given signal number (usually one
1012	of the C<SIGxxx> constants).	1408	of the C<SIGxxx> constants).
1013		1409
		1410	=item int signum [read-only]
		1411
		1412	The signal the watcher watches out for.
		1413
1014	=back	1414	=back
1015		1415
1016		1416
1017	=head2 C<ev_child> - wait for pid status changes	1417	=head2 C<ev_child> - watch out for process status changes
1018		1418
1019	Child watchers trigger when your process receives a SIGCHLD in response to	1419	Child watchers trigger when your process receives a SIGCHLD in response to
1020	some child status changes (most typically when a child of yours dies).	1420	some child status changes (most typically when a child of yours dies).
		1421
		1422	=head3 Watcher-Specific Functions and Data Members
1021		1423
1022	=over 4	1424	=over 4
1023		1425
1024	=item ev_child_init (ev_child *, callback, int pid)	1426	=item ev_child_init (ev_child *, callback, int pid)
1025		1427
…		…
1030	at the C<rstatus> member of the C<ev_child> watcher structure to see	1432	at the C<rstatus> member of the C<ev_child> watcher structure to see
1031	the status word (use the macros from C<sys/wait.h> and see your systems	1433	the status word (use the macros from C<sys/wait.h> and see your systems
1032	C<waitpid> documentation). The C<rpid> member contains the pid of the	1434	C<waitpid> documentation). The C<rpid> member contains the pid of the
1033	process causing the status change.	1435	process causing the status change.
1034		1436
		1437	=item int pid [read-only]
		1438
		1439	The process id this watcher watches out for, or C<0>, meaning any process id.
		1440
		1441	=item int rpid [read-write]
		1442
		1443	The process id that detected a status change.
		1444
		1445	=item int rstatus [read-write]
		1446
		1447	The process exit/trace status caused by C<rpid> (see your systems
		1448	C<waitpid> and C<sys/wait.h> documentation for details).
		1449
1035	=back	1450	=back
1036		1451
1037	Example: try to exit cleanly on SIGINT and SIGTERM.	1452	Example: Try to exit cleanly on SIGINT and SIGTERM.
1038		1453
1039	static void	1454	static void
1040	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)	1455	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1041	{	1456	{
1042	ev_unloop (loop, EVUNLOOP_ALL);	1457	ev_unloop (loop, EVUNLOOP_ALL);
…		…
1045	struct ev_signal signal_watcher;	1460	struct ev_signal signal_watcher;
1046	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1461	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1047	ev_signal_start (loop, &sigint_cb);	1462	ev_signal_start (loop, &sigint_cb);
1048		1463
1049		1464
		1465	=head2 C<ev_stat> - did the file attributes just change?
		1466
		1467	This watches a filesystem path for attribute changes. That is, it calls
		1468	C<stat> regularly (or when the OS says it changed) and sees if it changed
		1469	compared to the last time, invoking the callback if it did.
		1470
		1471	The path does not need to exist: changing from "path exists" to "path does
		1472	not exist" is a status change like any other. The condition "path does
		1473	not exist" is signified by the C<st_nlink> field being zero (which is
		1474	otherwise always forced to be at least one) and all the other fields of
		1475	the stat buffer having unspecified contents.
		1476
		1477	The path I<should> be absolute and I<must not> end in a slash. If it is
		1478	relative and your working directory changes, the behaviour is undefined.
		1479
		1480	Since there is no standard to do this, the portable implementation simply
		1481	calls C<stat (2)> regularly on the path to see if it changed somehow. You
		1482	can specify a recommended polling interval for this case. If you specify
		1483	a polling interval of C<0> (highly recommended!) then a I<suitable,
		1484	unspecified default> value will be used (which you can expect to be around
		1485	five seconds, although this might change dynamically). Libev will also
		1486	impose a minimum interval which is currently around C<0.1>, but thats
		1487	usually overkill.
		1488
		1489	This watcher type is not meant for massive numbers of stat watchers,
		1490	as even with OS-supported change notifications, this can be
		1491	resource-intensive.
		1492
		1493	At the time of this writing, only the Linux inotify interface is
		1494	implemented (implementing kqueue support is left as an exercise for the
		1495	reader). Inotify will be used to give hints only and should not change the
		1496	semantics of C<ev_stat> watchers, which means that libev sometimes needs
		1497	to fall back to regular polling again even with inotify, but changes are
		1498	usually detected immediately, and if the file exists there will be no
		1499	polling.
		1500
		1501	=head3 The special problem of stat time resolution
		1502
		1503	The C<stat ()> syscall only supports full-second resolution portably, and
		1504	even on systems where the resolution is higher, many filesystems still
		1505	only support whole seconds.
		1506
		1507	That means that, if the time is the only thing that changes, you might
		1508	miss updates: on the first update, C<ev_stat> detects a change and calls
		1509	your callback, which does something. When there is another update within
		1510	the same second, C<ev_stat> will be unable to detect it.
		1511
		1512	The solution to this is to delay acting on a change for a second (or till
		1513	the next second boundary), using a roughly one-second delay C<ev_timer>
		1514	(C<ev_timer_set (w, 0., 1.01); ev_timer_again (loop, w)>). The C<.01>
		1515	is added to work around small timing inconsistencies of some operating
		1516	systems.
		1517
		1518	=head3 Watcher-Specific Functions and Data Members
		1519
		1520	=over 4
		1521
		1522	=item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)
		1523
		1524	=item ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)
		1525
		1526	Configures the watcher to wait for status changes of the given
		1527	C<path>. The C<interval> is a hint on how quickly a change is expected to
		1528	be detected and should normally be specified as C<0> to let libev choose
		1529	a suitable value. The memory pointed to by C<path> must point to the same
		1530	path for as long as the watcher is active.
		1531
		1532	The callback will be receive C<EV_STAT> when a change was detected,
		1533	relative to the attributes at the time the watcher was started (or the
		1534	last change was detected).
		1535
		1536	=item ev_stat_stat (ev_stat *)
		1537
		1538	Updates the stat buffer immediately with new values. If you change the
		1539	watched path in your callback, you could call this fucntion to avoid
		1540	detecting this change (while introducing a race condition). Can also be
		1541	useful simply to find out the new values.
		1542
		1543	=item ev_statdata attr [read-only]
		1544
		1545	The most-recently detected attributes of the file. Although the type is of
		1546	C<ev_statdata>, this is usually the (or one of the) C<struct stat> types
		1547	suitable for your system. If the C<st_nlink> member is C<0>, then there
		1548	was some error while C<stat>ing the file.
		1549
		1550	=item ev_statdata prev [read-only]
		1551
		1552	The previous attributes of the file. The callback gets invoked whenever
		1553	C<prev> != C<attr>.
		1554
		1555	=item ev_tstamp interval [read-only]
		1556
		1557	The specified interval.
		1558
		1559	=item const char *path [read-only]
		1560
		1561	The filesystem path that is being watched.
		1562
		1563	=back
		1564
		1565	Example: Watch C</etc/passwd> for attribute changes.
		1566
		1567	static void
		1568	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
		1569	{
		1570	/* /etc/passwd changed in some way */
		1571	if (w->attr.st_nlink)
		1572	{
		1573	printf ("passwd current size %ld\n", (long)w->attr.st_size);
		1574	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
		1575	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
		1576	}
		1577	else
		1578	/* you shalt not abuse printf for puts */
		1579	puts ("wow, /etc/passwd is not there, expect problems. "
		1580	"if this is windows, they already arrived\n");
		1581	}
		1582
		1583	...
		1584	ev_stat passwd;
		1585
		1586	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);
		1587	ev_stat_start (loop, &passwd);
		1588
		1589	Example: Like above, but additionally use a one-second delay so we do not
		1590	miss updates (however, frequent updates will delay processing, too, so
		1591	one might do the work both on C<ev_stat> callback invocation I<and> on
		1592	C<ev_timer> callback invocation).
		1593
		1594	static ev_stat passwd;
		1595	static ev_timer timer;
		1596
		1597	static void
		1598	timer_cb (EV_P_ ev_timer *w, int revents)
		1599	{
		1600	ev_timer_stop (EV_A_ w);
		1601
		1602	/* now it's one second after the most recent passwd change */
		1603	}
		1604
		1605	static void
		1606	stat_cb (EV_P_ ev_stat *w, int revents)
		1607	{
		1608	/* reset the one-second timer */
		1609	ev_timer_again (EV_A_ &timer);
		1610	}
		1611
		1612	...
		1613	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);
		1614	ev_stat_start (loop, &passwd);
		1615	ev_timer_init (&timer, timer_cb, 0., 1.01);
		1616
		1617
1050	=head2 C<ev_idle> - when you've got nothing better to do	1618	=head2 C<ev_idle> - when you've got nothing better to do...
1051		1619
1052	Idle watchers trigger events when there are no other events are pending	1620	Idle watchers trigger events when no other events of the same or higher
1053	(prepare, check and other idle watchers do not count). That is, as long	1621	priority are pending (prepare, check and other idle watchers do not
1054	as your process is busy handling sockets or timeouts (or even signals,	1622	count).
1055	imagine) it will not be triggered. But when your process is idle all idle	1623
1056	watchers are being called again and again, once per event loop iteration -	1624	That is, as long as your process is busy handling sockets or timeouts
		1625	(or even signals, imagine) of the same or higher priority it will not be
		1626	triggered. But when your process is idle (or only lower-priority watchers
		1627	are pending), the idle watchers are being called once per event loop
1057	until stopped, that is, or your process receives more events and becomes	1628	iteration - until stopped, that is, or your process receives more events
1058	busy.	1629	and becomes busy again with higher priority stuff.
1059		1630
1060	The most noteworthy effect is that as long as any idle watchers are	1631	The most noteworthy effect is that as long as any idle watchers are
1061	active, the process will not block when waiting for new events.	1632	active, the process will not block when waiting for new events.
1062		1633
1063	Apart from keeping your process non-blocking (which is a useful	1634	Apart from keeping your process non-blocking (which is a useful
1064	effect on its own sometimes), idle watchers are a good place to do	1635	effect on its own sometimes), idle watchers are a good place to do
1065	"pseudo-background processing", or delay processing stuff to after the	1636	"pseudo-background processing", or delay processing stuff to after the
1066	event loop has handled all outstanding events.	1637	event loop has handled all outstanding events.
1067		1638
		1639	=head3 Watcher-Specific Functions and Data Members
		1640
1068	=over 4	1641	=over 4
1069		1642
1070	=item ev_idle_init (ev_signal *, callback)	1643	=item ev_idle_init (ev_signal *, callback)
1071		1644
1072	Initialises and configures the idle watcher - it has no parameters of any	1645	Initialises and configures the idle watcher - it has no parameters of any
1073	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,	1646	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,
1074	believe me.	1647	believe me.
1075		1648
1076	=back	1649	=back
1077		1650
1078	Example: dynamically allocate an C<ev_idle>, start it, and in the	1651	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1079	callback, free it. Alos, use no error checking, as usual.	1652	callback, free it. Also, use no error checking, as usual.
1080		1653
1081	static void	1654	static void
1082	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)	1655	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1083	{	1656	{
1084	free (w);	1657	free (w);
…		…
1089	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));	1662	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1090	ev_idle_init (idle_watcher, idle_cb);	1663	ev_idle_init (idle_watcher, idle_cb);
1091	ev_idle_start (loop, idle_cb);	1664	ev_idle_start (loop, idle_cb);
1092		1665
1093		1666
1094	=head2 C<ev_prepare> and C<ev_check> - customise your event loop	1667	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!
1095		1668
1096	Prepare and check watchers are usually (but not always) used in tandem:	1669	Prepare and check watchers are usually (but not always) used in tandem:
1097	prepare watchers get invoked before the process blocks and check watchers	1670	prepare watchers get invoked before the process blocks and check watchers
1098	afterwards.	1671	afterwards.
1099		1672
		1673	You I<must not> call C<ev_loop> or similar functions that enter
		1674	the current event loop from either C<ev_prepare> or C<ev_check>
		1675	watchers. Other loops than the current one are fine, however. The
		1676	rationale behind this is that you do not need to check for recursion in
		1677	those watchers, i.e. the sequence will always be C<ev_prepare>, blocking,
		1678	C<ev_check> so if you have one watcher of each kind they will always be
		1679	called in pairs bracketing the blocking call.
		1680
1100	Their main purpose is to integrate other event mechanisms into libev and	1681	Their main purpose is to integrate other event mechanisms into libev and
1101	their use is somewhat advanced. This could be used, for example, to track	1682	their use is somewhat advanced. This could be used, for example, to track
1102	variable changes, implement your own watchers, integrate net-snmp or a	1683	variable changes, implement your own watchers, integrate net-snmp or a
1103	coroutine library and lots more.	1684	coroutine library and lots more. They are also occasionally useful if
		1685	you cache some data and want to flush it before blocking (for example,
		1686	in X programs you might want to do an C<XFlush ()> in an C<ev_prepare>
		1687	watcher).
1104		1688
1105	This is done by examining in each prepare call which file descriptors need	1689	This is done by examining in each prepare call which file descriptors need
1106	to be watched by the other library, registering C<ev_io> watchers for	1690	to be watched by the other library, registering C<ev_io> watchers for
1107	them and starting an C<ev_timer> watcher for any timeouts (many libraries	1691	them and starting an C<ev_timer> watcher for any timeouts (many libraries
1108	provide just this functionality). Then, in the check watcher you check for	1692	provide just this functionality). Then, in the check watcher you check for
…		…
1118	with priority higher than or equal to the event loop and one coroutine	1702	with priority higher than or equal to the event loop and one coroutine
1119	of lower priority, but only once, using idle watchers to keep the event	1703	of lower priority, but only once, using idle watchers to keep the event
1120	loop from blocking if lower-priority coroutines are active, thus mapping	1704	loop from blocking if lower-priority coroutines are active, thus mapping
1121	low-priority coroutines to idle/background tasks).	1705	low-priority coroutines to idle/background tasks).
1122		1706
		1707	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)
		1708	priority, to ensure that they are being run before any other watchers
		1709	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,
		1710	too) should not activate ("feed") events into libev. While libev fully
		1711	supports this, they will be called before other C<ev_check> watchers
		1712	did their job. As C<ev_check> watchers are often used to embed other
		1713	(non-libev) event loops those other event loops might be in an unusable
		1714	state until their C<ev_check> watcher ran (always remind yourself to
		1715	coexist peacefully with others).
		1716
		1717	=head3 Watcher-Specific Functions and Data Members
		1718
1123	=over 4	1719	=over 4
1124		1720
1125	=item ev_prepare_init (ev_prepare *, callback)	1721	=item ev_prepare_init (ev_prepare *, callback)
1126		1722
1127	=item ev_check_init (ev_check *, callback)	1723	=item ev_check_init (ev_check *, callback)
…		…
1130	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>	1726	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>
1131	macros, but using them is utterly, utterly and completely pointless.	1727	macros, but using them is utterly, utterly and completely pointless.
1132		1728
1133	=back	1729	=back
1134		1730
1135	Example: *TODO*.	1731	There are a number of principal ways to embed other event loops or modules
		1732	into libev. Here are some ideas on how to include libadns into libev
		1733	(there is a Perl module named C<EV::ADNS> that does this, which you could
		1734	use for an actually working example. Another Perl module named C<EV::Glib>
		1735	embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV
		1736	into the Glib event loop).
1136		1737
		1738	Method 1: Add IO watchers and a timeout watcher in a prepare handler,
		1739	and in a check watcher, destroy them and call into libadns. What follows
		1740	is pseudo-code only of course. This requires you to either use a low
		1741	priority for the check watcher or use C<ev_clear_pending> explicitly, as
		1742	the callbacks for the IO/timeout watchers might not have been called yet.
1137		1743
		1744	static ev_io iow [nfd];
		1745	static ev_timer tw;
		1746
		1747	static void
		1748	io_cb (ev_loop *loop, ev_io *w, int revents)
		1749	{
		1750	}
		1751
		1752	// create io watchers for each fd and a timer before blocking
		1753	static void
		1754	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
		1755	{
		1756	int timeout = 3600000;
		1757	struct pollfd fds [nfd];
		1758	// actual code will need to loop here and realloc etc.
		1759	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
		1760
		1761	/* the callback is illegal, but won't be called as we stop during check */
		1762	ev_timer_init (&tw, 0, timeout * 1e-3);
		1763	ev_timer_start (loop, &tw);
		1764
		1765	// create one ev_io per pollfd
		1766	for (int i = 0; i < nfd; ++i)
		1767	{
		1768	ev_io_init (iow + i, io_cb, fds [i].fd,
		1769	((fds [i].events & POLLIN ? EV_READ : 0)
		1770	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
		1771
		1772	fds [i].revents = 0;
		1773	ev_io_start (loop, iow + i);
		1774	}
		1775	}
		1776
		1777	// stop all watchers after blocking
		1778	static void
		1779	adns_check_cb (ev_loop *loop, ev_check *w, int revents)
		1780	{
		1781	ev_timer_stop (loop, &tw);
		1782
		1783	for (int i = 0; i < nfd; ++i)
		1784	{
		1785	// set the relevant poll flags
		1786	// could also call adns_processreadable etc. here
		1787	struct pollfd *fd = fds + i;
		1788	int revents = ev_clear_pending (iow + i);
		1789	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
		1790	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
		1791
		1792	// now stop the watcher
		1793	ev_io_stop (loop, iow + i);
		1794	}
		1795
		1796	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1797	}
		1798
		1799	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
		1800	in the prepare watcher and would dispose of the check watcher.
		1801
		1802	Method 3: If the module to be embedded supports explicit event
		1803	notification (adns does), you can also make use of the actual watcher
		1804	callbacks, and only destroy/create the watchers in the prepare watcher.
		1805
		1806	static void
		1807	timer_cb (EV_P_ ev_timer *w, int revents)
		1808	{
		1809	adns_state ads = (adns_state)w->data;
		1810	update_now (EV_A);
		1811
		1812	adns_processtimeouts (ads, &tv_now);
		1813	}
		1814
		1815	static void
		1816	io_cb (EV_P_ ev_io *w, int revents)
		1817	{
		1818	adns_state ads = (adns_state)w->data;
		1819	update_now (EV_A);
		1820
		1821	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
		1822	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
		1823	}
		1824
		1825	// do not ever call adns_afterpoll
		1826
		1827	Method 4: Do not use a prepare or check watcher because the module you
		1828	want to embed is too inflexible to support it. Instead, youc na override
		1829	their poll function. The drawback with this solution is that the main
		1830	loop is now no longer controllable by EV. The C<Glib::EV> module does
		1831	this.
		1832
		1833	static gint
		1834	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
		1835	{
		1836	int got_events = 0;
		1837
		1838	for (n = 0; n < nfds; ++n)
		1839	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
		1840
		1841	if (timeout >= 0)
		1842	// create/start timer
		1843
		1844	// poll
		1845	ev_loop (EV_A_ 0);
		1846
		1847	// stop timer again
		1848	if (timeout >= 0)
		1849	ev_timer_stop (EV_A_ &to);
		1850
		1851	// stop io watchers again - their callbacks should have set
		1852	for (n = 0; n < nfds; ++n)
		1853	ev_io_stop (EV_A_ iow [n]);
		1854
		1855	return got_events;
		1856	}
		1857
		1858
1138	=head2 C<ev_embed> - when one backend isn't enough	1859	=head2 C<ev_embed> - when one backend isn't enough...
1139		1860
1140	This is a rather advanced watcher type that lets you embed one event loop	1861	This is a rather advanced watcher type that lets you embed one event loop
1141	into another (currently only C<ev_io> events are supported in the embedded	1862	into another (currently only C<ev_io> events are supported in the embedded
1142	loop, other types of watchers might be handled in a delayed or incorrect	1863	loop, other types of watchers might be handled in a delayed or incorrect
1143	fashion and must not be used).	1864	fashion and must not be used).
…		…
1203	ev_embed_start (loop_hi, &embed);	1924	ev_embed_start (loop_hi, &embed);
1204	}	1925	}
1205	else	1926	else
1206	loop_lo = loop_hi;	1927	loop_lo = loop_hi;
1207		1928
		1929	=head3 Watcher-Specific Functions and Data Members
		1930
1208	=over 4	1931	=over 4
1209		1932
1210	=item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)	1933	=item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)
1211		1934
1212	=item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)	1935	=item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)
…		…
1221		1944
1222	Make a single, non-blocking sweep over the embedded loop. This works	1945	Make a single, non-blocking sweep over the embedded loop. This works
1223	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	1946	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
1224	apropriate way for embedded loops.	1947	apropriate way for embedded loops.
1225		1948
		1949	=item struct ev_loop *other [read-only]
		1950
		1951	The embedded event loop.
		1952
		1953	=back
		1954
		1955
		1956	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
		1957
		1958	Fork watchers are called when a C<fork ()> was detected (usually because
		1959	whoever is a good citizen cared to tell libev about it by calling
		1960	C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the
		1961	event loop blocks next and before C<ev_check> watchers are being called,
		1962	and only in the child after the fork. If whoever good citizen calling
		1963	C<ev_default_fork> cheats and calls it in the wrong process, the fork
		1964	handlers will be invoked, too, of course.
		1965
		1966	=head3 Watcher-Specific Functions and Data Members
		1967
		1968	=over 4
		1969
		1970	=item ev_fork_init (ev_signal *, callback)
		1971
		1972	Initialises and configures the fork watcher - it has no parameters of any
		1973	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
		1974	believe me.
		1975
1226	=back	1976	=back
1227		1977
1228		1978
1229	=head1 OTHER FUNCTIONS	1979	=head1 OTHER FUNCTIONS
1230		1980
…		…
1318		2068
1319	To use it,	2069	To use it,
1320		2070
1321	#include <ev++.h>	2071	#include <ev++.h>
1322		2072
1323	(it is not installed by default). This automatically includes F<ev.h>	2073	This automatically includes F<ev.h> and puts all of its definitions (many
1324	and puts all of its definitions (many of them macros) into the global	2074	of them macros) into the global namespace. All C++ specific things are
1325	namespace. All C++ specific things are put into the C<ev> namespace.	2075	put into the C<ev> namespace. It should support all the same embedding
		2076	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
1326		2077
1327	It should support all the same embedding options as F<ev.h>, most notably	2078	Care has been taken to keep the overhead low. The only data member the C++
1328	C<EV_MULTIPLICITY>.	2079	classes add (compared to plain C-style watchers) is the event loop pointer
		2080	that the watcher is associated with (or no additional members at all if
		2081	you disable C<EV_MULTIPLICITY> when embedding libev).
		2082
		2083	Currently, functions, and static and non-static member functions can be
		2084	used as callbacks. Other types should be easy to add as long as they only
		2085	need one additional pointer for context. If you need support for other
		2086	types of functors please contact the author (preferably after implementing
		2087	it).
1329		2088
1330	Here is a list of things available in the C<ev> namespace:	2089	Here is a list of things available in the C<ev> namespace:
1331		2090
1332	=over 4	2091	=over 4
1333		2092
…		…
1349		2108
1350	All of those classes have these methods:	2109	All of those classes have these methods:
1351		2110
1352	=over 4	2111	=over 4
1353		2112
1354	=item ev::TYPE::TYPE (object *, object::method *)	2113	=item ev::TYPE::TYPE ()
1355		2114
1356	=item ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)	2115	=item ev::TYPE::TYPE (struct ev_loop *)
1357		2116
1358	=item ev::TYPE::~TYPE	2117	=item ev::TYPE::~TYPE
1359		2118
1360	The constructor takes a pointer to an object and a method pointer to	2119	The constructor (optionally) takes an event loop to associate the watcher
1361	the event handler callback to call in this class. The constructor calls	2120	with. If it is omitted, it will use C<EV_DEFAULT>.
1362	C<ev_init> for you, which means you have to call the C<set> method	2121
1363	before starting it. If you do not specify a loop then the constructor	2122	The constructor calls C<ev_init> for you, which means you have to call the
1364	automatically associates the default loop with this watcher.	2123	C<set> method before starting it.
		2124
		2125	It will not set a callback, however: You have to call the templated C<set>
		2126	method to set a callback before you can start the watcher.
		2127
		2128	(The reason why you have to use a method is a limitation in C++ which does
		2129	not allow explicit template arguments for constructors).
1365		2130
1366	The destructor automatically stops the watcher if it is active.	2131	The destructor automatically stops the watcher if it is active.
		2132
		2133	=item w->set<class, &class::method> (object *)
		2134
		2135	This method sets the callback method to call. The method has to have a
		2136	signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as
		2137	first argument and the C<revents> as second. The object must be given as
		2138	parameter and is stored in the C<data> member of the watcher.
		2139
		2140	This method synthesizes efficient thunking code to call your method from
		2141	the C callback that libev requires. If your compiler can inline your
		2142	callback (i.e. it is visible to it at the place of the C<set> call and
		2143	your compiler is good :), then the method will be fully inlined into the
		2144	thunking function, making it as fast as a direct C callback.
		2145
		2146	Example: simple class declaration and watcher initialisation
		2147
		2148	struct myclass
		2149	{
		2150	void io_cb (ev::io &w, int revents) { }
		2151	}
		2152
		2153	myclass obj;
		2154	ev::io iow;
		2155	iow.set <myclass, &myclass::io_cb> (&obj);
		2156
		2157	=item w->set<function> (void *data = 0)
		2158
		2159	Also sets a callback, but uses a static method or plain function as
		2160	callback. The optional C<data> argument will be stored in the watcher's
		2161	C<data> member and is free for you to use.
		2162
		2163	The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>.
		2164
		2165	See the method-C<set> above for more details.
		2166
		2167	Example:
		2168
		2169	static void io_cb (ev::io &w, int revents) { }
		2170	iow.set <io_cb> ();
1367		2171
1368	=item w->set (struct ev_loop *)	2172	=item w->set (struct ev_loop *)
1369		2173
1370	Associates a different C<struct ev_loop> with this watcher. You can only	2174	Associates a different C<struct ev_loop> with this watcher. You can only
1371	do this when the watcher is inactive (and not pending either).	2175	do this when the watcher is inactive (and not pending either).
1372		2176
1373	=item w->set ([args])	2177	=item w->set ([args])
1374		2178
1375	Basically the same as C<ev_TYPE_set>, with the same args. Must be	2179	Basically the same as C<ev_TYPE_set>, with the same args. Must be
1376	called at least once. Unlike the C counterpart, an active watcher gets	2180	called at least once. Unlike the C counterpart, an active watcher gets
1377	automatically stopped and restarted.	2181	automatically stopped and restarted when reconfiguring it with this
		2182	method.
1378		2183
1379	=item w->start ()	2184	=item w->start ()
1380		2185
1381	Starts the watcher. Note that there is no C<loop> argument as the	2186	Starts the watcher. Note that there is no C<loop> argument, as the
1382	constructor already takes the loop.	2187	constructor already stores the event loop.
1383		2188
1384	=item w->stop ()	2189	=item w->stop ()
1385		2190
1386	Stops the watcher if it is active. Again, no C<loop> argument.	2191	Stops the watcher if it is active. Again, no C<loop> argument.
1387		2192
1388	=item w->again () C<ev::timer>, C<ev::periodic> only	2193	=item w->again () (C<ev::timer>, C<ev::periodic> only)
1389		2194
1390	For C<ev::timer> and C<ev::periodic>, this invokes the corresponding	2195	For C<ev::timer> and C<ev::periodic>, this invokes the corresponding
1391	C<ev_TYPE_again> function.	2196	C<ev_TYPE_again> function.
1392		2197
1393	=item w->sweep () C<ev::embed> only	2198	=item w->sweep () (C<ev::embed> only)
1394		2199
1395	Invokes C<ev_embed_sweep>.	2200	Invokes C<ev_embed_sweep>.
		2201
		2202	=item w->update () (C<ev::stat> only)
		2203
		2204	Invokes C<ev_stat_stat>.
1396		2205
1397	=back	2206	=back
1398		2207
1399	=back	2208	=back
1400		2209
…		…
1408		2217
1409	myclass ();	2218	myclass ();
1410	}	2219	}
1411		2220
1412	myclass::myclass (int fd)	2221	myclass::myclass (int fd)
1413	: io (this, &myclass::io_cb),
1414	idle (this, &myclass::idle_cb)
1415	{	2222	{
		2223	io .set <myclass, &myclass::io_cb > (this);
		2224	idle.set <myclass, &myclass::idle_cb> (this);
		2225
1416	io.start (fd, ev::READ);	2226	io.start (fd, ev::READ);
1417	}	2227	}
		2228
		2229
		2230	=head1 MACRO MAGIC
		2231
		2232	Libev can be compiled with a variety of options, the most fundamantal
		2233	of which is C<EV_MULTIPLICITY>. This option determines whether (most)
		2234	functions and callbacks have an initial C<struct ev_loop *> argument.
		2235
		2236	To make it easier to write programs that cope with either variant, the
		2237	following macros are defined:
		2238
		2239	=over 4
		2240
		2241	=item C<EV_A>, C<EV_A_>
		2242
		2243	This provides the loop I<argument> for functions, if one is required ("ev
		2244	loop argument"). The C<EV_A> form is used when this is the sole argument,
		2245	C<EV_A_> is used when other arguments are following. Example:
		2246
		2247	ev_unref (EV_A);
		2248	ev_timer_add (EV_A_ watcher);
		2249	ev_loop (EV_A_ 0);
		2250
		2251	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
		2252	which is often provided by the following macro.
		2253
		2254	=item C<EV_P>, C<EV_P_>
		2255
		2256	This provides the loop I<parameter> for functions, if one is required ("ev
		2257	loop parameter"). The C<EV_P> form is used when this is the sole parameter,
		2258	C<EV_P_> is used when other parameters are following. Example:
		2259
		2260	// this is how ev_unref is being declared
		2261	static void ev_unref (EV_P);
		2262
		2263	// this is how you can declare your typical callback
		2264	static void cb (EV_P_ ev_timer *w, int revents)
		2265
		2266	It declares a parameter C<loop> of type C<struct ev_loop *>, quite
		2267	suitable for use with C<EV_A>.
		2268
		2269	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
		2270
		2271	Similar to the other two macros, this gives you the value of the default
		2272	loop, if multiple loops are supported ("ev loop default").
		2273
		2274	=back
		2275
		2276	Example: Declare and initialise a check watcher, utilising the above
		2277	macros so it will work regardless of whether multiple loops are supported
		2278	or not.
		2279
		2280	static void
		2281	check_cb (EV_P_ ev_timer *w, int revents)
		2282	{
		2283	ev_check_stop (EV_A_ w);
		2284	}
		2285
		2286	ev_check check;
		2287	ev_check_init (&check, check_cb);
		2288	ev_check_start (EV_DEFAULT_ &check);
		2289	ev_loop (EV_DEFAULT_ 0);
1418		2290
1419	=head1 EMBEDDING	2291	=head1 EMBEDDING
1420		2292
1421	Libev can (and often is) directly embedded into host	2293	Libev can (and often is) directly embedded into host
1422	applications. Examples of applications that embed it include the Deliantra	2294	applications. Examples of applications that embed it include the Deliantra
1423	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)	2295	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
1424	and rxvt-unicode.	2296	and rxvt-unicode.
1425		2297
1426	The goal is to enable you to just copy the neecssary files into your	2298	The goal is to enable you to just copy the necessary files into your
1427	source directory without having to change even a single line in them, so	2299	source directory without having to change even a single line in them, so
1428	you can easily upgrade by simply copying (or having a checked-out copy of	2300	you can easily upgrade by simply copying (or having a checked-out copy of
1429	libev somewhere in your source tree).	2301	libev somewhere in your source tree).
1430		2302
1431	=head2 FILESETS	2303	=head2 FILESETS
…		…
1462	ev_vars.h	2334	ev_vars.h
1463	ev_wrap.h	2335	ev_wrap.h
1464		2336
1465	ev_win32.c required on win32 platforms only	2337	ev_win32.c required on win32 platforms only
1466		2338
1467	ev_select.c only when select backend is enabled (which is is by default)	2339	ev_select.c only when select backend is enabled (which is enabled by default)
1468	ev_poll.c only when poll backend is enabled (disabled by default)	2340	ev_poll.c only when poll backend is enabled (disabled by default)
1469	ev_epoll.c only when the epoll backend is enabled (disabled by default)	2341	ev_epoll.c only when the epoll backend is enabled (disabled by default)
1470	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	2342	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
1471	ev_port.c only when the solaris port backend is enabled (disabled by default)	2343	ev_port.c only when the solaris port backend is enabled (disabled by default)
1472		2344
1473	F<ev.c> includes the backend files directly when enabled, so you only need	2345	F<ev.c> includes the backend files directly when enabled, so you only need
1474	to compile a single file.	2346	to compile this single file.
1475		2347
1476	=head3 LIBEVENT COMPATIBILITY API	2348	=head3 LIBEVENT COMPATIBILITY API
1477		2349
1478	To include the libevent compatibility API, also include:	2350	To include the libevent compatibility API, also include:
1479		2351
…		…
1492		2364
1493	=head3 AUTOCONF SUPPORT	2365	=head3 AUTOCONF SUPPORT
1494		2366
1495	Instead of using C<EV_STANDALONE=1> and providing your config in	2367	Instead of using C<EV_STANDALONE=1> and providing your config in
1496	whatever way you want, you can also C<m4_include([libev.m4])> in your	2368	whatever way you want, you can also C<m4_include([libev.m4])> in your
1497	F<configure.ac> and leave C<EV_STANDALONE> off. F<ev.c> will then include	2369	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then
1498	F<config.h> and configure itself accordingly.	2370	include F<config.h> and configure itself accordingly.
1499		2371
1500	For this of course you need the m4 file:	2372	For this of course you need the m4 file:
1501		2373
1502	libev.m4	2374	libev.m4
1503		2375
…		…
1521		2393
1522	If defined to be C<1>, libev will try to detect the availability of the	2394	If defined to be C<1>, libev will try to detect the availability of the
1523	monotonic clock option at both compiletime and runtime. Otherwise no use	2395	monotonic clock option at both compiletime and runtime. Otherwise no use
1524	of the monotonic clock option will be attempted. If you enable this, you	2396	of the monotonic clock option will be attempted. If you enable this, you
1525	usually have to link against librt or something similar. Enabling it when	2397	usually have to link against librt or something similar. Enabling it when
1526	the functionality isn't available is safe, though, althoguh you have	2398	the functionality isn't available is safe, though, although you have
1527	to make sure you link against any libraries where the C<clock_gettime>	2399	to make sure you link against any libraries where the C<clock_gettime>
1528	function is hiding in (often F<-lrt>).	2400	function is hiding in (often F<-lrt>).
1529		2401
1530	=item EV_USE_REALTIME	2402	=item EV_USE_REALTIME
1531		2403
1532	If defined to be C<1>, libev will try to detect the availability of the	2404	If defined to be C<1>, libev will try to detect the availability of the
1533	realtime clock option at compiletime (and assume its availability at	2405	realtime clock option at compiletime (and assume its availability at
1534	runtime if successful). Otherwise no use of the realtime clock option will	2406	runtime if successful). Otherwise no use of the realtime clock option will
1535	be attempted. This effectively replaces C<gettimeofday> by C<clock_get	2407	be attempted. This effectively replaces C<gettimeofday> by C<clock_get
1536	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries	2408	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the
1537	in the description of C<EV_USE_MONOTONIC>, though.	2409	note about libraries in the description of C<EV_USE_MONOTONIC>, though.
		2410
		2411	=item EV_USE_NANOSLEEP
		2412
		2413	If defined to be C<1>, libev will assume that C<nanosleep ()> is available
		2414	and will use it for delays. Otherwise it will use C<select ()>.
1538		2415
1539	=item EV_USE_SELECT	2416	=item EV_USE_SELECT
1540		2417
1541	If undefined or defined to be C<1>, libev will compile in support for the	2418	If undefined or defined to be C<1>, libev will compile in support for the
1542	C<select>(2) backend. No attempt at autodetection will be done: if no	2419	C<select>(2) backend. No attempt at autodetection will be done: if no
…		…
1583	otherwise another method will be used as fallback. This is the preferred	2460	otherwise another method will be used as fallback. This is the preferred
1584	backend for BSD and BSD-like systems, although on most BSDs kqueue only	2461	backend for BSD and BSD-like systems, although on most BSDs kqueue only
1585	supports some types of fds correctly (the only platform we found that	2462	supports some types of fds correctly (the only platform we found that
1586	supports ptys for example was NetBSD), so kqueue might be compiled in, but	2463	supports ptys for example was NetBSD), so kqueue might be compiled in, but
1587	not be used unless explicitly requested. The best way to use it is to find	2464	not be used unless explicitly requested. The best way to use it is to find
1588	out wether kqueue supports your type of fd properly and use an embedded	2465	out whether kqueue supports your type of fd properly and use an embedded
1589	kqueue loop.	2466	kqueue loop.
1590		2467
1591	=item EV_USE_PORT	2468	=item EV_USE_PORT
1592		2469
1593	If defined to be C<1>, libev will compile in support for the Solaris	2470	If defined to be C<1>, libev will compile in support for the Solaris
…		…
1596	backend for Solaris 10 systems.	2473	backend for Solaris 10 systems.
1597		2474
1598	=item EV_USE_DEVPOLL	2475	=item EV_USE_DEVPOLL
1599		2476
1600	reserved for future expansion, works like the USE symbols above.	2477	reserved for future expansion, works like the USE symbols above.
		2478
		2479	=item EV_USE_INOTIFY
		2480
		2481	If defined to be C<1>, libev will compile in support for the Linux inotify
		2482	interface to speed up C<ev_stat> watchers. Its actual availability will
		2483	be detected at runtime.
1601		2484
1602	=item EV_H	2485	=item EV_H
1603		2486
1604	The name of the F<ev.h> header file used to include it. The default if	2487	The name of the F<ev.h> header file used to include it. The default if
1605	undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This	2488	undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This
…		…
1629	will have the C<struct ev_loop *> as first argument, and you can create	2512	will have the C<struct ev_loop *> as first argument, and you can create
1630	additional independent event loops. Otherwise there will be no support	2513	additional independent event loops. Otherwise there will be no support
1631	for multiple event loops and there is no first event loop pointer	2514	for multiple event loops and there is no first event loop pointer
1632	argument. Instead, all functions act on the single default loop.	2515	argument. Instead, all functions act on the single default loop.
1633		2516
		2517	=item EV_MINPRI
		2518
		2519	=item EV_MAXPRI
		2520
		2521	The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to
		2522	C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can
		2523	provide for more priorities by overriding those symbols (usually defined
		2524	to be C<-2> and C<2>, respectively).
		2525
		2526	When doing priority-based operations, libev usually has to linearly search
		2527	all the priorities, so having many of them (hundreds) uses a lot of space
		2528	and time, so using the defaults of five priorities (-2 .. +2) is usually
		2529	fine.
		2530
		2531	If your embedding app does not need any priorities, defining these both to
		2532	C<0> will save some memory and cpu.
		2533
1634	=item EV_PERIODICS	2534	=item EV_PERIODIC_ENABLE
1635		2535
1636	If undefined or defined to be C<1>, then periodic timers are supported,	2536	If undefined or defined to be C<1>, then periodic timers are supported. If
1637	otherwise not. This saves a few kb of code.	2537	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2538	code.
		2539
		2540	=item EV_IDLE_ENABLE
		2541
		2542	If undefined or defined to be C<1>, then idle watchers are supported. If
		2543	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2544	code.
		2545
		2546	=item EV_EMBED_ENABLE
		2547
		2548	If undefined or defined to be C<1>, then embed watchers are supported. If
		2549	defined to be C<0>, then they are not.
		2550
		2551	=item EV_STAT_ENABLE
		2552
		2553	If undefined or defined to be C<1>, then stat watchers are supported. If
		2554	defined to be C<0>, then they are not.
		2555
		2556	=item EV_FORK_ENABLE
		2557
		2558	If undefined or defined to be C<1>, then fork watchers are supported. If
		2559	defined to be C<0>, then they are not.
		2560
		2561	=item EV_MINIMAL
		2562
		2563	If you need to shave off some kilobytes of code at the expense of some
		2564	speed, define this symbol to C<1>. Currently only used for gcc to override
		2565	some inlining decisions, saves roughly 30% codesize of amd64.
		2566
		2567	=item EV_PID_HASHSIZE
		2568
		2569	C<ev_child> watchers use a small hash table to distribute workload by
		2570	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
		2571	than enough. If you need to manage thousands of children you might want to
		2572	increase this value (I<must> be a power of two).
		2573
		2574	=item EV_INOTIFY_HASHSIZE
		2575
		2576	C<ev_stat> watchers use a small hash table to distribute workload by
		2577	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
		2578	usually more than enough. If you need to manage thousands of C<ev_stat>
		2579	watchers you might want to increase this value (I<must> be a power of
		2580	two).
1638		2581
1639	=item EV_COMMON	2582	=item EV_COMMON
1640		2583
1641	By default, all watchers have a C<void *data> member. By redefining	2584	By default, all watchers have a C<void *data> member. By redefining
1642	this macro to a something else you can include more and other types of	2585	this macro to a something else you can include more and other types of
…		…
1647		2590
1648	#define EV_COMMON \	2591	#define EV_COMMON \
1649	SV *self; /* contains this struct */ \	2592	SV *self; /* contains this struct */ \
1650	SV *cb_sv, *fh /* note no trailing ";" */	2593	SV *cb_sv, *fh /* note no trailing ";" */
1651		2594
1652	=item EV_CB_DECLARE(type)	2595	=item EV_CB_DECLARE (type)
1653		2596
1654	=item EV_CB_INVOKE(watcher,revents)	2597	=item EV_CB_INVOKE (watcher, revents)
1655		2598
1656	=item ev_set_cb(ev,cb)	2599	=item ev_set_cb (ev, cb)
1657		2600
1658	Can be used to change the callback member declaration in each watcher,	2601	Can be used to change the callback member declaration in each watcher,
1659	and the way callbacks are invoked and set. Must expand to a struct member	2602	and the way callbacks are invoked and set. Must expand to a struct member
1660	definition and a statement, respectively. See the F<ev.v> header file for	2603	definition and a statement, respectively. See the F<ev.h> header file for
1661	their default definitions. One possible use for overriding these is to	2604	their default definitions. One possible use for overriding these is to
1662	avoid the ev_loop pointer as first argument in all cases, or to use method	2605	avoid the C<struct ev_loop *> as first argument in all cases, or to use
1663	calls instead of plain function calls in C++.	2606	method calls instead of plain function calls in C++.
		2607
		2608	=head2 EXPORTED API SYMBOLS
		2609
		2610	If you need to re-export the API (e.g. via a dll) and you need a list of
		2611	exported symbols, you can use the provided F<Symbol.*> files which list
		2612	all public symbols, one per line:
		2613
		2614	Symbols.ev for libev proper
		2615	Symbols.event for the libevent emulation
		2616
		2617	This can also be used to rename all public symbols to avoid clashes with
		2618	multiple versions of libev linked together (which is obviously bad in
		2619	itself, but sometimes it is inconvinient to avoid this).
		2620
		2621	A sed command like this will create wrapper C<#define>'s that you need to
		2622	include before including F<ev.h>:
		2623
		2624	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h
		2625
		2626	This would create a file F<wrap.h> which essentially looks like this:
		2627
		2628	#define ev_backend myprefix_ev_backend
		2629	#define ev_check_start myprefix_ev_check_start
		2630	#define ev_check_stop myprefix_ev_check_stop
		2631	...
1664		2632
1665	=head2 EXAMPLES	2633	=head2 EXAMPLES
1666		2634
1667	For a real-world example of a program the includes libev	2635	For a real-world example of a program the includes libev
1668	verbatim, you can have a look at the EV perl module	2636	verbatim, you can have a look at the EV perl module
…		…
1671	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file	2639	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file
1672	will be compiled. It is pretty complex because it provides its own header	2640	will be compiled. It is pretty complex because it provides its own header
1673	file.	2641	file.
1674		2642
1675	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	2643	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
1676	that everybody includes and which overrides some autoconf choices:	2644	that everybody includes and which overrides some configure choices:
1677		2645
		2646	#define EV_MINIMAL 1
1678	#define EV_USE_POLL 0	2647	#define EV_USE_POLL 0
1679	#define EV_MULTIPLICITY 0	2648	#define EV_MULTIPLICITY 0
1680	#define EV_PERIODICS 0	2649	#define EV_PERIODIC_ENABLE 0
		2650	#define EV_STAT_ENABLE 0
		2651	#define EV_FORK_ENABLE 0
1681	#define EV_CONFIG_H <config.h>	2652	#define EV_CONFIG_H <config.h>
		2653	#define EV_MINPRI 0
		2654	#define EV_MAXPRI 0
1682		2655
1683	#include "ev++.h"	2656	#include "ev++.h"
1684		2657
1685	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	2658	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
1686		2659
1687	#include "rxvttoolkit.h"	2660	#include "ev_cpp.h"
1688
1689	/* darwin has problems with its header files in C++, requiring this namespace juggling */
1690	using namespace ev;
1691
1692	#include "ev.c"	2661	#include "ev.c"
		2662
		2663
		2664	=head1 COMPLEXITIES
		2665
		2666	In this section the complexities of (many of) the algorithms used inside
		2667	libev will be explained. For complexity discussions about backends see the
		2668	documentation for C<ev_default_init>.
		2669
		2670	All of the following are about amortised time: If an array needs to be
		2671	extended, libev needs to realloc and move the whole array, but this
		2672	happens asymptotically never with higher number of elements, so O(1) might
		2673	mean it might do a lengthy realloc operation in rare cases, but on average
		2674	it is much faster and asymptotically approaches constant time.
		2675
		2676	=over 4
		2677
		2678	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
		2679
		2680	This means that, when you have a watcher that triggers in one hour and
		2681	there are 100 watchers that would trigger before that then inserting will
		2682	have to skip roughly seven (C<ld 100>) of these watchers.
		2683
		2684	=item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers)
		2685
		2686	That means that changing a timer costs less than removing/adding them
		2687	as only the relative motion in the event queue has to be paid for.
		2688
		2689	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
		2690
		2691	These just add the watcher into an array or at the head of a list.
		2692
		2693	=item Stopping check/prepare/idle watchers: O(1)
		2694
		2695	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
		2696
		2697	These watchers are stored in lists then need to be walked to find the
		2698	correct watcher to remove. The lists are usually short (you don't usually
		2699	have many watchers waiting for the same fd or signal).
		2700
		2701	=item Finding the next timer in each loop iteration: O(1)
		2702
		2703	By virtue of using a binary heap, the next timer is always found at the
		2704	beginning of the storage array.
		2705
		2706	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
		2707
		2708	A change means an I/O watcher gets started or stopped, which requires
		2709	libev to recalculate its status (and possibly tell the kernel, depending
		2710	on backend and wether C<ev_io_set> was used).
		2711
		2712	=item Activating one watcher (putting it into the pending state): O(1)
		2713
		2714	=item Priority handling: O(number_of_priorities)
		2715
		2716	Priorities are implemented by allocating some space for each
		2717	priority. When doing priority-based operations, libev usually has to
		2718	linearly search all the priorities, but starting/stopping and activating
		2719	watchers becomes O(1) w.r.t. prioritiy handling.
		2720
		2721	=back
1693		2722
1694		2723
1695	=head1 AUTHOR	2724	=head1 AUTHOR
1696		2725
1697	Marc Lehmann <libev@schmorp.de>.	2726	Marc Lehmann <libev@schmorp.de>.

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