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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
472		655
473		656
474	=head1 ANATOMY OF A WATCHER	657	=head1 ANATOMY OF A WATCHER
…		…
565	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
566	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
567	(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
568	C<ev_loop> from blocking).	751	C<ev_loop> from blocking).
569		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
570	=item C<EV_ERROR>	762	=item C<EV_ERROR>
571		763
572	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
573	happen because the watcher could not be properly started because libev	765	happen because the watcher could not be properly started because libev
574	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
…		…
645	=item bool ev_is_pending (ev_TYPE *watcher)	837	=item bool ev_is_pending (ev_TYPE *watcher)
646		838
647	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
648	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
649	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
650	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
651	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).
652		845
653	=item callback = ev_cb (ev_TYPE *watcher)	846	=item callback ev_cb (ev_TYPE *watcher)
654		847
655	Returns the callback currently set on the watcher.	848	Returns the callback currently set on the watcher.
656		849
657	=item ev_cb_set (ev_TYPE *watcher, callback)	850	=item ev_cb_set (ev_TYPE *watcher, callback)
658		851
659	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
660	(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>.
661		894
662	=back	895	=back
663		896
664		897
665	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	898	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
686	{	919	{
687	struct my_io *w = (struct my_io *)w_;	920	struct my_io *w = (struct my_io *)w_;
688	...	921	...
689	}	922	}
690		923
691	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
692	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	}
693		955
694		956
695	=head1 WATCHER TYPES	957	=head1 WATCHER TYPES
696		958
697	This section describes each watcher in detail, but will not repeat	959	This section describes each watcher in detail, but will not repeat
…		…
742	it is best to always use non-blocking I/O: An extra C<read>(2) returning	1004	it is best to always use non-blocking I/O: An extra C<read>(2) returning
743	C<EAGAIN> is far preferable to a program hanging until some data arrives.	1005	C<EAGAIN> is far preferable to a program hanging until some data arrives.
744		1006
745	If you cannot run the fd in non-blocking mode (for example you should not	1007	If you cannot run the fd in non-blocking mode (for example you should not
746	play around with an Xlib connection), then you have to seperately re-test	1008	play around with an Xlib connection), then you have to seperately re-test
747	wether a file descriptor is really ready with a known-to-be good interface	1009	whether a file descriptor is really ready with a known-to-be good interface
748	such as poll (fortunately in our Xlib example, Xlib already does this on	1010	such as poll (fortunately in our Xlib example, Xlib already does this on
749	its own, so its quite safe to use).	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
750		1058
751	=over 4	1059	=over 4
752		1060
753	=item ev_io_init (ev_io *, callback, int fd, int events)	1061	=item ev_io_init (ev_io *, callback, int fd, int events)
754		1062
…		…
766		1074
767	The events being watched.	1075	The events being watched.
768		1076
769	=back	1077	=back
770		1078
771	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
772	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
773	attempt to read a whole line in the callback:	1081	attempt to read a whole line in the callback.
774		1082
775	static void	1083	static void
776	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)
777	{	1085	{
778	ev_io_stop (loop, w);	1086	ev_io_stop (loop, w);
…		…
808		1116
809	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,
810	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
811	order of execution is undefined.	1119	order of execution is undefined.
812		1120
		1121	=head3 Watcher-Specific Functions and Data Members
		1122
813	=over 4	1123	=over 4
814		1124
815	=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)
816		1126
817	=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)
…		…
830	=item ev_timer_again (loop)	1140	=item ev_timer_again (loop)
831		1141
832	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
833	repeating. The exact semantics are:	1143	repeating. The exact semantics are:
834		1144
		1145	If the timer is pending, its pending status is cleared.
		1146
835	If the timer is started but nonrepeating, stop it.	1147	If the timer is started but nonrepeating, stop it (as if it timed out).
836		1148
837	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
838	value), or reset the running timer to the repeat value.	1150	C<repeat> value), or reset the running timer to the C<repeat> value.
839		1151
840	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
841	example: Imagine you have a tcp connection and you want a so-called	1153	example: Imagine you have a tcp connection and you want a so-called idle
842	idle timeout, that is, you want to be called when there have been,	1154	timeout, that is, you want to be called when there have been, say, 60
843	say, 60 seconds of inactivity on the socket. The easiest way to do	1155	seconds of inactivity on the socket. The easiest way to do this is to
844	this is to configure an C<ev_timer> with C<after>=C<repeat>=C<60> and calling	1156	configure an C<ev_timer> with a C<repeat> value of C<60> and then call
845	C<ev_timer_again> each time you successfully read or write some data. If	1157	C<ev_timer_again> each time you successfully read or write some data. If
846	you go into an idle state where you do not expect data to travel on the	1158	you go into an idle state where you do not expect data to travel on the
847	socket, you can stop the timer, and again will automatically restart it if	1159	socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will
848	need be.	1160	automatically restart it if need be.
849		1161
850	You can also ignore the C<after> value and C<ev_timer_start> altogether	1162	That means you can ignore the C<after> value and C<ev_timer_start>
851	and only ever use the C<repeat> value:	1163	altogether and only ever use the C<repeat> value and C<ev_timer_again>:
852		1164
853	ev_timer_init (timer, callback, 0., 5.);	1165	ev_timer_init (timer, callback, 0., 5.);
854	ev_timer_again (loop, timer);	1166	ev_timer_again (loop, timer);
855	...	1167	...
856	timer->again = 17.;	1168	timer->again = 17.;
857	ev_timer_again (loop, timer);	1169	ev_timer_again (loop, timer);
858	...	1170	...
859	timer->again = 10.;	1171	timer->again = 10.;
860	ev_timer_again (loop, timer);	1172	ev_timer_again (loop, timer);
861		1173
862	This is more efficient then stopping/starting the timer eahc time you want	1174	This is more slightly efficient then stopping/starting the timer each time
863	to modify its timeout value.	1175	you want to modify its timeout value.
864		1176
865	=item ev_tstamp repeat [read-write]	1177	=item ev_tstamp repeat [read-write]
866		1178
867	The current C<repeat> value. Will be used each time the watcher times out	1179	The current C<repeat> value. Will be used each time the watcher times out
868	or C<ev_timer_again> is called and determines the next timeout (if any),	1180	or C<ev_timer_again> is called and determines the next timeout (if any),
869	which is also when any modifications are taken into account.	1181	which is also when any modifications are taken into account.
870		1182
871	=back	1183	=back
872		1184
873	Example: create a timer that fires after 60 seconds.	1185	Example: Create a timer that fires after 60 seconds.
874		1186
875	static void	1187	static void
876	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)
877	{	1189	{
878	.. one minute over, w is actually stopped right here	1190	.. one minute over, w is actually stopped right here
…		…
880		1192
881	struct ev_timer mytimer;	1193	struct ev_timer mytimer;
882	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1194	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
883	ev_timer_start (loop, &mytimer);	1195	ev_timer_start (loop, &mytimer);
884		1196
885	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
886	inactivity.	1198	inactivity.
887		1199
888	static void	1200	static void
889	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)
890	{	1202	{
…		…
910	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
911	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
912	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 ()
913	+ 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
914	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
915	roughly 10 seconds later and of course not if you reset your system time	1227	roughly 10 seconds later).
916	again).
917		1228
918	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
919	triggering an event on eahc midnight, local time.	1230	triggering an event on each midnight, local time or other, complicated,
		1231	rules.
920		1232
921	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
922	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
923	during the same loop iteration then order of execution is undefined.	1235	during the same loop iteration then order of execution is undefined.
924		1236
		1237	=head3 Watcher-Specific Functions and Data Members
		1238
925	=over 4	1239	=over 4
926		1240
927	=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)
928		1242
929	=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)
…		…
931	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
932	operation, and we will explain them from simplest to complex:	1246	operation, and we will explain them from simplest to complex:
933		1247
934	=over 4	1248	=over 4
935		1249
936	=item * absolute timer (interval = reschedule_cb = 0)	1250	=item * absolute timer (at = time, interval = reschedule_cb = 0)
937		1251
938	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
939	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,
940	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
941	system time reaches or surpasses this time.	1255	system time reaches or surpasses this time.
942		1256
943	=item * non-repeating interval timer (interval > 0, reschedule_cb = 0)	1257	=item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
944		1258
945	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
946	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)
947	of any time jumps.	1261	and then repeat, regardless of any time jumps.
948		1262
949	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
950	time:	1264	time:
951		1265
952	ev_periodic_set (&periodic, 0., 3600., 0);	1266	ev_periodic_set (&periodic, 0., 3600., 0);
…		…
958		1272
959	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
960	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
961	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.
962		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
963	=item * manual reschedule mode (reschedule_cb = callback)	1281	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
964		1282
965	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
966	ignored. Instead, each time the periodic watcher gets scheduled, the	1284	ignored. Instead, each time the periodic watcher gets scheduled, the
967	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
968	current time as second argument.	1286	current time as second argument.
969		1287
970	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,
971	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,
972	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
973	starting a prepare watcher).	1291	starting an C<ev_prepare> watcher, which is legal).
974		1292
975	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,
976	ev_tstamp now)>, e.g.:	1294	ev_tstamp now)>, e.g.:
977		1295
978	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)
…		…
1001	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
1002	when you changed some parameters or the reschedule callback would return	1320	when you changed some parameters or the reschedule callback would return
1003	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
1004	program when the crontabs have changed).	1322	program when the crontabs have changed).
1005		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
1006	=item ev_tstamp interval [read-write]	1332	=item ev_tstamp interval [read-write]
1007		1333
1008	The current interval value. Can be modified any time, but changes only	1334	The current interval value. Can be modified any time, but changes only
1009	take effect when the periodic timer fires or C<ev_periodic_again> is being	1335	take effect when the periodic timer fires or C<ev_periodic_again> is being
1010	called.	1336	called.
…		…
1013		1339
1014	The current reschedule callback, or C<0>, if this functionality is	1340	The current reschedule callback, or C<0>, if this functionality is
1015	switched off. Can be changed any time, but changes only take effect when	1341	switched off. Can be changed any time, but changes only take effect when
1016	the periodic timer fires or C<ev_periodic_again> is being called.	1342	the periodic timer fires or C<ev_periodic_again> is being called.
1017		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
1018	=back	1349	=back
1019		1350
1020	Example: call a callback every hour, or, more precisely, whenever the	1351	Example: Call a callback every hour, or, more precisely, whenever the
1021	system clock is divisible by 3600. The callback invocation times have	1352	system clock is divisible by 3600. The callback invocation times have
1022	potentially a lot of jittering, but good long-term stability.	1353	potentially a lot of jittering, but good long-term stability.
1023		1354
1024	static void	1355	static void
1025	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)
…		…
1029		1360
1030	struct ev_periodic hourly_tick;	1361	struct ev_periodic hourly_tick;
1031	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1362	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1032	ev_periodic_start (loop, &hourly_tick);	1363	ev_periodic_start (loop, &hourly_tick);
1033		1364
1034	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:
1035		1366
1036	#include <math.h>	1367	#include <math.h>
1037		1368
1038	static ev_tstamp	1369	static ev_tstamp
1039	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1370	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
…		…
1041	return fmod (now, 3600.) + 3600.;	1372	return fmod (now, 3600.) + 3600.;
1042	}	1373	}
1043		1374
1044	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);
1045		1376
1046	Example: call a callback every hour, starting now:	1377	Example: Call a callback every hour, starting now:
1047		1378
1048	struct ev_periodic hourly_tick;	1379	struct ev_periodic hourly_tick;
1049	ev_periodic_init (&hourly_tick, clock_cb,	1380	ev_periodic_init (&hourly_tick, clock_cb,
1050	fmod (ev_now (loop), 3600.), 3600., 0);	1381	fmod (ev_now (loop), 3600.), 3600., 0);
1051	ev_periodic_start (loop, &hourly_tick);	1382	ev_periodic_start (loop, &hourly_tick);
…		…
1063	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
1064	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
1065	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
1066	SIG_DFL (regardless of what it was set to before).	1397	SIG_DFL (regardless of what it was set to before).
1067		1398
		1399	=head3 Watcher-Specific Functions and Data Members
		1400
1068	=over 4	1401	=over 4
1069		1402
1070	=item ev_signal_init (ev_signal *, callback, int signum)	1403	=item ev_signal_init (ev_signal *, callback, int signum)
1071		1404
1072	=item ev_signal_set (ev_signal *, int signum)	1405	=item ev_signal_set (ev_signal *, int signum)
…		…
1083		1416
1084	=head2 C<ev_child> - watch out for process status changes	1417	=head2 C<ev_child> - watch out for process status changes
1085		1418
1086	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
1087	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
1088		1423
1089	=over 4	1424	=over 4
1090		1425
1091	=item ev_child_init (ev_child *, callback, int pid)	1426	=item ev_child_init (ev_child *, callback, int pid)
1092		1427
…		…
1112	The process exit/trace status caused by C<rpid> (see your systems	1447	The process exit/trace status caused by C<rpid> (see your systems
1113	C<waitpid> and C<sys/wait.h> documentation for details).	1448	C<waitpid> and C<sys/wait.h> documentation for details).
1114		1449
1115	=back	1450	=back
1116		1451
1117	Example: try to exit cleanly on SIGINT and SIGTERM.	1452	Example: Try to exit cleanly on SIGINT and SIGTERM.
1118		1453
1119	static void	1454	static void
1120	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)
1121	{	1456	{
1122	ev_unloop (loop, EVUNLOOP_ALL);	1457	ev_unloop (loop, EVUNLOOP_ALL);
…		…
1137	not exist" is a status change like any other. The condition "path does	1472	not exist" is a status change like any other. The condition "path does
1138	not exist" is signified by the C<st_nlink> field being zero (which is	1473	not exist" is signified by the C<st_nlink> field being zero (which is
1139	otherwise always forced to be at least one) and all the other fields of	1474	otherwise always forced to be at least one) and all the other fields of
1140	the stat buffer having unspecified contents.	1475	the stat buffer having unspecified contents.
1141		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
1142	Since there is no standard to do this, the portable implementation simply	1480	Since there is no standard to do this, the portable implementation simply
1143	calls C<stat (2)> regulalry on the path to see if it changed somehow. You	1481	calls C<stat (2)> regularly on the path to see if it changed somehow. You
1144	can specify a recommended polling interval for this case. If you specify	1482	can specify a recommended polling interval for this case. If you specify
1145	a polling interval of C<0> (highly recommended!) then a I<suitable,	1483	a polling interval of C<0> (highly recommended!) then a I<suitable,
1146	unspecified default> value will be used (which you can expect to be around	1484	unspecified default> value will be used (which you can expect to be around
1147	five seconds, although this might change dynamically). Libev will also	1485	five seconds, although this might change dynamically). Libev will also
1148	impose a minimum interval which is currently around C<0.1>, but thats	1486	impose a minimum interval which is currently around C<0.1>, but thats
…		…
1150		1488
1151	This watcher type is not meant for massive numbers of stat watchers,	1489	This watcher type is not meant for massive numbers of stat watchers,
1152	as even with OS-supported change notifications, this can be	1490	as even with OS-supported change notifications, this can be
1153	resource-intensive.	1491	resource-intensive.
1154		1492
1155	At the time of this writing, no specific OS backends are implemented, but	1493	At the time of this writing, only the Linux inotify interface is
1156	if demand increases, at least a kqueue and inotify backend will be added.	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 Watcher-Specific Functions and Data Members
1157		1502
1158	=over 4	1503	=over 4
1159		1504
1160	=item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)	1505	=item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)
1161		1506
…		…
1225	ev_stat_start (loop, &passwd);	1570	ev_stat_start (loop, &passwd);
1226		1571
1227		1572
1228	=head2 C<ev_idle> - when you've got nothing better to do...	1573	=head2 C<ev_idle> - when you've got nothing better to do...
1229		1574
1230	Idle watchers trigger events when there are no other events are pending	1575	Idle watchers trigger events when no other events of the same or higher
1231	(prepare, check and other idle watchers do not count). That is, as long	1576	priority are pending (prepare, check and other idle watchers do not
1232	as your process is busy handling sockets or timeouts (or even signals,	1577	count).
1233	imagine) it will not be triggered. But when your process is idle all idle	1578
1234	watchers are being called again and again, once per event loop iteration -	1579	That is, as long as your process is busy handling sockets or timeouts
		1580	(or even signals, imagine) of the same or higher priority it will not be
		1581	triggered. But when your process is idle (or only lower-priority watchers
		1582	are pending), the idle watchers are being called once per event loop
1235	until stopped, that is, or your process receives more events and becomes	1583	iteration - until stopped, that is, or your process receives more events
1236	busy.	1584	and becomes busy again with higher priority stuff.
1237		1585
1238	The most noteworthy effect is that as long as any idle watchers are	1586	The most noteworthy effect is that as long as any idle watchers are
1239	active, the process will not block when waiting for new events.	1587	active, the process will not block when waiting for new events.
1240		1588
1241	Apart from keeping your process non-blocking (which is a useful	1589	Apart from keeping your process non-blocking (which is a useful
1242	effect on its own sometimes), idle watchers are a good place to do	1590	effect on its own sometimes), idle watchers are a good place to do
1243	"pseudo-background processing", or delay processing stuff to after the	1591	"pseudo-background processing", or delay processing stuff to after the
1244	event loop has handled all outstanding events.	1592	event loop has handled all outstanding events.
1245		1593
		1594	=head3 Watcher-Specific Functions and Data Members
		1595
1246	=over 4	1596	=over 4
1247		1597
1248	=item ev_idle_init (ev_signal *, callback)	1598	=item ev_idle_init (ev_signal *, callback)
1249		1599
1250	Initialises and configures the idle watcher - it has no parameters of any	1600	Initialises and configures the idle watcher - it has no parameters of any
1251	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,	1601	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,
1252	believe me.	1602	believe me.
1253		1603
1254	=back	1604	=back
1255		1605
1256	Example: dynamically allocate an C<ev_idle>, start it, and in the	1606	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1257	callback, free it. Alos, use no error checking, as usual.	1607	callback, free it. Also, use no error checking, as usual.
1258		1608
1259	static void	1609	static void
1260	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)	1610	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1261	{	1611	{
1262	free (w);	1612	free (w);
…		…
1307	with priority higher than or equal to the event loop and one coroutine	1657	with priority higher than or equal to the event loop and one coroutine
1308	of lower priority, but only once, using idle watchers to keep the event	1658	of lower priority, but only once, using idle watchers to keep the event
1309	loop from blocking if lower-priority coroutines are active, thus mapping	1659	loop from blocking if lower-priority coroutines are active, thus mapping
1310	low-priority coroutines to idle/background tasks).	1660	low-priority coroutines to idle/background tasks).
1311		1661
		1662	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)
		1663	priority, to ensure that they are being run before any other watchers
		1664	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,
		1665	too) should not activate ("feed") events into libev. While libev fully
		1666	supports this, they will be called before other C<ev_check> watchers
		1667	did their job. As C<ev_check> watchers are often used to embed other
		1668	(non-libev) event loops those other event loops might be in an unusable
		1669	state until their C<ev_check> watcher ran (always remind yourself to
		1670	coexist peacefully with others).
		1671
		1672	=head3 Watcher-Specific Functions and Data Members
		1673
1312	=over 4	1674	=over 4
1313		1675
1314	=item ev_prepare_init (ev_prepare *, callback)	1676	=item ev_prepare_init (ev_prepare *, callback)
1315		1677
1316	=item ev_check_init (ev_check *, callback)	1678	=item ev_check_init (ev_check *, callback)
…		…
1319	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>	1681	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>
1320	macros, but using them is utterly, utterly and completely pointless.	1682	macros, but using them is utterly, utterly and completely pointless.
1321		1683
1322	=back	1684	=back
1323		1685
1324	Example: To include a library such as adns, you would add IO watchers	1686	There are a number of principal ways to embed other event loops or modules
1325	and a timeout watcher in a prepare handler, as required by libadns, and	1687	into libev. Here are some ideas on how to include libadns into libev
		1688	(there is a Perl module named C<EV::ADNS> that does this, which you could
		1689	use for an actually working example. Another Perl module named C<EV::Glib>
		1690	embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV
		1691	into the Glib event loop).
		1692
		1693	Method 1: Add IO watchers and a timeout watcher in a prepare handler,
1326	in a check watcher, destroy them and call into libadns. What follows is	1694	and in a check watcher, destroy them and call into libadns. What follows
1327	pseudo-code only of course:	1695	is pseudo-code only of course. This requires you to either use a low
		1696	priority for the check watcher or use C<ev_clear_pending> explicitly, as
		1697	the callbacks for the IO/timeout watchers might not have been called yet.
1328		1698
1329	static ev_io iow [nfd];	1699	static ev_io iow [nfd];
1330	static ev_timer tw;	1700	static ev_timer tw;
1331		1701
1332	static void	1702	static void
1333	io_cb (ev_loop *loop, ev_io *w, int revents)	1703	io_cb (ev_loop *loop, ev_io *w, int revents)
1334	{	1704	{
1335	// set the relevant poll flags
1336	// could also call adns_processreadable etc. here
1337	struct pollfd *fd = (struct pollfd *)w->data;
1338	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1339	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1340	}	1705	}
1341		1706
1342	// create io watchers for each fd and a timer before blocking	1707	// create io watchers for each fd and a timer before blocking
1343	static void	1708	static void
1344	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)	1709	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1345	{	1710	{
1346	int timeout = 3600000;truct pollfd fds [nfd];	1711	int timeout = 3600000;
		1712	struct pollfd fds [nfd];
1347	// actual code will need to loop here and realloc etc.	1713	// actual code will need to loop here and realloc etc.
1348	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1714	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1349		1715
1350	/* the callback is illegal, but won't be called as we stop during check */	1716	/* the callback is illegal, but won't be called as we stop during check */
1351	ev_timer_init (&tw, 0, timeout * 1e-3);	1717	ev_timer_init (&tw, 0, timeout * 1e-3);
1352	ev_timer_start (loop, &tw);	1718	ev_timer_start (loop, &tw);
1353		1719
1354	// create on ev_io per pollfd	1720	// create one ev_io per pollfd
1355	for (int i = 0; i < nfd; ++i)	1721	for (int i = 0; i < nfd; ++i)
1356	{	1722	{
1357	ev_io_init (iow + i, io_cb, fds [i].fd,	1723	ev_io_init (iow + i, io_cb, fds [i].fd,
1358	((fds [i].events & POLLIN ? EV_READ : 0)	1724	((fds [i].events & POLLIN ? EV_READ : 0)
1359	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	1725	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1360		1726
1361	fds [i].revents = 0;	1727	fds [i].revents = 0;
1362	iow [i].data = fds + i;
1363	ev_io_start (loop, iow + i);	1728	ev_io_start (loop, iow + i);
1364	}	1729	}
1365	}	1730	}
1366		1731
1367	// stop all watchers after blocking	1732	// stop all watchers after blocking
…		…
1369	adns_check_cb (ev_loop *loop, ev_check *w, int revents)	1734	adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1370	{	1735	{
1371	ev_timer_stop (loop, &tw);	1736	ev_timer_stop (loop, &tw);
1372		1737
1373	for (int i = 0; i < nfd; ++i)	1738	for (int i = 0; i < nfd; ++i)
		1739	{
		1740	// set the relevant poll flags
		1741	// could also call adns_processreadable etc. here
		1742	struct pollfd *fd = fds + i;
		1743	int revents = ev_clear_pending (iow + i);
		1744	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
		1745	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
		1746
		1747	// now stop the watcher
1374	ev_io_stop (loop, iow + i);	1748	ev_io_stop (loop, iow + i);
		1749	}
1375		1750
1376	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	1751	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1752	}
		1753
		1754	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
		1755	in the prepare watcher and would dispose of the check watcher.
		1756
		1757	Method 3: If the module to be embedded supports explicit event
		1758	notification (adns does), you can also make use of the actual watcher
		1759	callbacks, and only destroy/create the watchers in the prepare watcher.
		1760
		1761	static void
		1762	timer_cb (EV_P_ ev_timer *w, int revents)
		1763	{
		1764	adns_state ads = (adns_state)w->data;
		1765	update_now (EV_A);
		1766
		1767	adns_processtimeouts (ads, &tv_now);
		1768	}
		1769
		1770	static void
		1771	io_cb (EV_P_ ev_io *w, int revents)
		1772	{
		1773	adns_state ads = (adns_state)w->data;
		1774	update_now (EV_A);
		1775
		1776	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
		1777	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
		1778	}
		1779
		1780	// do not ever call adns_afterpoll
		1781
		1782	Method 4: Do not use a prepare or check watcher because the module you
		1783	want to embed is too inflexible to support it. Instead, youc na override
		1784	their poll function. The drawback with this solution is that the main
		1785	loop is now no longer controllable by EV. The C<Glib::EV> module does
		1786	this.
		1787
		1788	static gint
		1789	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
		1790	{
		1791	int got_events = 0;
		1792
		1793	for (n = 0; n < nfds; ++n)
		1794	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
		1795
		1796	if (timeout >= 0)
		1797	// create/start timer
		1798
		1799	// poll
		1800	ev_loop (EV_A_ 0);
		1801
		1802	// stop timer again
		1803	if (timeout >= 0)
		1804	ev_timer_stop (EV_A_ &to);
		1805
		1806	// stop io watchers again - their callbacks should have set
		1807	for (n = 0; n < nfds; ++n)
		1808	ev_io_stop (EV_A_ iow [n]);
		1809
		1810	return got_events;
1377	}	1811	}
1378		1812
1379		1813
1380	=head2 C<ev_embed> - when one backend isn't enough...	1814	=head2 C<ev_embed> - when one backend isn't enough...
1381		1815
…		…
1445	ev_embed_start (loop_hi, &embed);	1879	ev_embed_start (loop_hi, &embed);
1446	}	1880	}
1447	else	1881	else
1448	loop_lo = loop_hi;	1882	loop_lo = loop_hi;
1449		1883
		1884	=head3 Watcher-Specific Functions and Data Members
		1885
1450	=over 4	1886	=over 4
1451		1887
1452	=item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)	1888	=item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)
1453		1889
1454	=item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)	1890	=item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)
…		…
1463		1899
1464	Make a single, non-blocking sweep over the embedded loop. This works	1900	Make a single, non-blocking sweep over the embedded loop. This works
1465	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	1901	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
1466	apropriate way for embedded loops.	1902	apropriate way for embedded loops.
1467		1903
1468	=item struct ev_loop *loop [read-only]	1904	=item struct ev_loop *other [read-only]
1469		1905
1470	The embedded event loop.	1906	The embedded event loop.
		1907
		1908	=back
		1909
		1910
		1911	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
		1912
		1913	Fork watchers are called when a C<fork ()> was detected (usually because
		1914	whoever is a good citizen cared to tell libev about it by calling
		1915	C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the
		1916	event loop blocks next and before C<ev_check> watchers are being called,
		1917	and only in the child after the fork. If whoever good citizen calling
		1918	C<ev_default_fork> cheats and calls it in the wrong process, the fork
		1919	handlers will be invoked, too, of course.
		1920
		1921	=head3 Watcher-Specific Functions and Data Members
		1922
		1923	=over 4
		1924
		1925	=item ev_fork_init (ev_signal *, callback)
		1926
		1927	Initialises and configures the fork watcher - it has no parameters of any
		1928	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
		1929	believe me.
1471		1930
1472	=back	1931	=back
1473		1932
1474		1933
1475	=head1 OTHER FUNCTIONS	1934	=head1 OTHER FUNCTIONS
…		…
1564		2023
1565	To use it,	2024	To use it,
1566		2025
1567	#include <ev++.h>	2026	#include <ev++.h>
1568		2027
1569	(it is not installed by default). This automatically includes F<ev.h>	2028	This automatically includes F<ev.h> and puts all of its definitions (many
1570	and puts all of its definitions (many of them macros) into the global	2029	of them macros) into the global namespace. All C++ specific things are
1571	namespace. All C++ specific things are put into the C<ev> namespace.	2030	put into the C<ev> namespace. It should support all the same embedding
		2031	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
1572		2032
1573	It should support all the same embedding options as F<ev.h>, most notably	2033	Care has been taken to keep the overhead low. The only data member the C++
1574	C<EV_MULTIPLICITY>.	2034	classes add (compared to plain C-style watchers) is the event loop pointer
		2035	that the watcher is associated with (or no additional members at all if
		2036	you disable C<EV_MULTIPLICITY> when embedding libev).
		2037
		2038	Currently, functions, and static and non-static member functions can be
		2039	used as callbacks. Other types should be easy to add as long as they only
		2040	need one additional pointer for context. If you need support for other
		2041	types of functors please contact the author (preferably after implementing
		2042	it).
1575		2043
1576	Here is a list of things available in the C<ev> namespace:	2044	Here is a list of things available in the C<ev> namespace:
1577		2045
1578	=over 4	2046	=over 4
1579		2047
…		…
1595		2063
1596	All of those classes have these methods:	2064	All of those classes have these methods:
1597		2065
1598	=over 4	2066	=over 4
1599		2067
1600	=item ev::TYPE::TYPE (object *, object::method *)	2068	=item ev::TYPE::TYPE ()
1601		2069
1602	=item ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)	2070	=item ev::TYPE::TYPE (struct ev_loop *)
1603		2071
1604	=item ev::TYPE::~TYPE	2072	=item ev::TYPE::~TYPE
1605		2073
1606	The constructor takes a pointer to an object and a method pointer to	2074	The constructor (optionally) takes an event loop to associate the watcher
1607	the event handler callback to call in this class. The constructor calls	2075	with. If it is omitted, it will use C<EV_DEFAULT>.
1608	C<ev_init> for you, which means you have to call the C<set> method	2076
1609	before starting it. If you do not specify a loop then the constructor	2077	The constructor calls C<ev_init> for you, which means you have to call the
1610	automatically associates the default loop with this watcher.	2078	C<set> method before starting it.
		2079
		2080	It will not set a callback, however: You have to call the templated C<set>
		2081	method to set a callback before you can start the watcher.
		2082
		2083	(The reason why you have to use a method is a limitation in C++ which does
		2084	not allow explicit template arguments for constructors).
1611		2085
1612	The destructor automatically stops the watcher if it is active.	2086	The destructor automatically stops the watcher if it is active.
		2087
		2088	=item w->set<class, &class::method> (object *)
		2089
		2090	This method sets the callback method to call. The method has to have a
		2091	signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as
		2092	first argument and the C<revents> as second. The object must be given as
		2093	parameter and is stored in the C<data> member of the watcher.
		2094
		2095	This method synthesizes efficient thunking code to call your method from
		2096	the C callback that libev requires. If your compiler can inline your
		2097	callback (i.e. it is visible to it at the place of the C<set> call and
		2098	your compiler is good :), then the method will be fully inlined into the
		2099	thunking function, making it as fast as a direct C callback.
		2100
		2101	Example: simple class declaration and watcher initialisation
		2102
		2103	struct myclass
		2104	{
		2105	void io_cb (ev::io &w, int revents) { }
		2106	}
		2107
		2108	myclass obj;
		2109	ev::io iow;
		2110	iow.set <myclass, &myclass::io_cb> (&obj);
		2111
		2112	=item w->set<function> (void *data = 0)
		2113
		2114	Also sets a callback, but uses a static method or plain function as
		2115	callback. The optional C<data> argument will be stored in the watcher's
		2116	C<data> member and is free for you to use.
		2117
		2118	The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>.
		2119
		2120	See the method-C<set> above for more details.
		2121
		2122	Example:
		2123
		2124	static void io_cb (ev::io &w, int revents) { }
		2125	iow.set <io_cb> ();
1613		2126
1614	=item w->set (struct ev_loop *)	2127	=item w->set (struct ev_loop *)
1615		2128
1616	Associates a different C<struct ev_loop> with this watcher. You can only	2129	Associates a different C<struct ev_loop> with this watcher. You can only
1617	do this when the watcher is inactive (and not pending either).	2130	do this when the watcher is inactive (and not pending either).
1618		2131
1619	=item w->set ([args])	2132	=item w->set ([args])
1620		2133
1621	Basically the same as C<ev_TYPE_set>, with the same args. Must be	2134	Basically the same as C<ev_TYPE_set>, with the same args. Must be
1622	called at least once. Unlike the C counterpart, an active watcher gets	2135	called at least once. Unlike the C counterpart, an active watcher gets
1623	automatically stopped and restarted.	2136	automatically stopped and restarted when reconfiguring it with this
		2137	method.
1624		2138
1625	=item w->start ()	2139	=item w->start ()
1626		2140
1627	Starts the watcher. Note that there is no C<loop> argument as the	2141	Starts the watcher. Note that there is no C<loop> argument, as the
1628	constructor already takes the loop.	2142	constructor already stores the event loop.
1629		2143
1630	=item w->stop ()	2144	=item w->stop ()
1631		2145
1632	Stops the watcher if it is active. Again, no C<loop> argument.	2146	Stops the watcher if it is active. Again, no C<loop> argument.
1633		2147
1634	=item w->again () C<ev::timer>, C<ev::periodic> only	2148	=item w->again () (C<ev::timer>, C<ev::periodic> only)
1635		2149
1636	For C<ev::timer> and C<ev::periodic>, this invokes the corresponding	2150	For C<ev::timer> and C<ev::periodic>, this invokes the corresponding
1637	C<ev_TYPE_again> function.	2151	C<ev_TYPE_again> function.
1638		2152
1639	=item w->sweep () C<ev::embed> only	2153	=item w->sweep () (C<ev::embed> only)
1640		2154
1641	Invokes C<ev_embed_sweep>.	2155	Invokes C<ev_embed_sweep>.
1642		2156
1643	=item w->update () C<ev::stat> only	2157	=item w->update () (C<ev::stat> only)
1644		2158
1645	Invokes C<ev_stat_stat>.	2159	Invokes C<ev_stat_stat>.
1646		2160
1647	=back	2161	=back
1648		2162
…		…
1658		2172
1659	myclass ();	2173	myclass ();
1660	}	2174	}
1661		2175
1662	myclass::myclass (int fd)	2176	myclass::myclass (int fd)
1663	: io (this, &myclass::io_cb),
1664	idle (this, &myclass::idle_cb)
1665	{	2177	{
		2178	io .set <myclass, &myclass::io_cb > (this);
		2179	idle.set <myclass, &myclass::idle_cb> (this);
		2180
1666	io.start (fd, ev::READ);	2181	io.start (fd, ev::READ);
1667	}	2182	}
		2183
		2184
		2185	=head1 MACRO MAGIC
		2186
		2187	Libev can be compiled with a variety of options, the most fundamantal
		2188	of which is C<EV_MULTIPLICITY>. This option determines whether (most)
		2189	functions and callbacks have an initial C<struct ev_loop *> argument.
		2190
		2191	To make it easier to write programs that cope with either variant, the
		2192	following macros are defined:
		2193
		2194	=over 4
		2195
		2196	=item C<EV_A>, C<EV_A_>
		2197
		2198	This provides the loop I<argument> for functions, if one is required ("ev
		2199	loop argument"). The C<EV_A> form is used when this is the sole argument,
		2200	C<EV_A_> is used when other arguments are following. Example:
		2201
		2202	ev_unref (EV_A);
		2203	ev_timer_add (EV_A_ watcher);
		2204	ev_loop (EV_A_ 0);
		2205
		2206	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
		2207	which is often provided by the following macro.
		2208
		2209	=item C<EV_P>, C<EV_P_>
		2210
		2211	This provides the loop I<parameter> for functions, if one is required ("ev
		2212	loop parameter"). The C<EV_P> form is used when this is the sole parameter,
		2213	C<EV_P_> is used when other parameters are following. Example:
		2214
		2215	// this is how ev_unref is being declared
		2216	static void ev_unref (EV_P);
		2217
		2218	// this is how you can declare your typical callback
		2219	static void cb (EV_P_ ev_timer *w, int revents)
		2220
		2221	It declares a parameter C<loop> of type C<struct ev_loop *>, quite
		2222	suitable for use with C<EV_A>.
		2223
		2224	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
		2225
		2226	Similar to the other two macros, this gives you the value of the default
		2227	loop, if multiple loops are supported ("ev loop default").
		2228
		2229	=back
		2230
		2231	Example: Declare and initialise a check watcher, utilising the above
		2232	macros so it will work regardless of whether multiple loops are supported
		2233	or not.
		2234
		2235	static void
		2236	check_cb (EV_P_ ev_timer *w, int revents)
		2237	{
		2238	ev_check_stop (EV_A_ w);
		2239	}
		2240
		2241	ev_check check;
		2242	ev_check_init (&check, check_cb);
		2243	ev_check_start (EV_DEFAULT_ &check);
		2244	ev_loop (EV_DEFAULT_ 0);
1668		2245
1669	=head1 EMBEDDING	2246	=head1 EMBEDDING
1670		2247
1671	Libev can (and often is) directly embedded into host	2248	Libev can (and often is) directly embedded into host
1672	applications. Examples of applications that embed it include the Deliantra	2249	applications. Examples of applications that embed it include the Deliantra
1673	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)	2250	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
1674	and rxvt-unicode.	2251	and rxvt-unicode.
1675		2252
1676	The goal is to enable you to just copy the neecssary files into your	2253	The goal is to enable you to just copy the necessary files into your
1677	source directory without having to change even a single line in them, so	2254	source directory without having to change even a single line in them, so
1678	you can easily upgrade by simply copying (or having a checked-out copy of	2255	you can easily upgrade by simply copying (or having a checked-out copy of
1679	libev somewhere in your source tree).	2256	libev somewhere in your source tree).
1680		2257
1681	=head2 FILESETS	2258	=head2 FILESETS
…		…
1712	ev_vars.h	2289	ev_vars.h
1713	ev_wrap.h	2290	ev_wrap.h
1714		2291
1715	ev_win32.c required on win32 platforms only	2292	ev_win32.c required on win32 platforms only
1716		2293
1717	ev_select.c only when select backend is enabled (which is by default)	2294	ev_select.c only when select backend is enabled (which is enabled by default)
1718	ev_poll.c only when poll backend is enabled (disabled by default)	2295	ev_poll.c only when poll backend is enabled (disabled by default)
1719	ev_epoll.c only when the epoll backend is enabled (disabled by default)	2296	ev_epoll.c only when the epoll backend is enabled (disabled by default)
1720	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	2297	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
1721	ev_port.c only when the solaris port backend is enabled (disabled by default)	2298	ev_port.c only when the solaris port backend is enabled (disabled by default)
1722		2299
…		…
1771		2348
1772	If defined to be C<1>, libev will try to detect the availability of the	2349	If defined to be C<1>, libev will try to detect the availability of the
1773	monotonic clock option at both compiletime and runtime. Otherwise no use	2350	monotonic clock option at both compiletime and runtime. Otherwise no use
1774	of the monotonic clock option will be attempted. If you enable this, you	2351	of the monotonic clock option will be attempted. If you enable this, you
1775	usually have to link against librt or something similar. Enabling it when	2352	usually have to link against librt or something similar. Enabling it when
1776	the functionality isn't available is safe, though, althoguh you have	2353	the functionality isn't available is safe, though, although you have
1777	to make sure you link against any libraries where the C<clock_gettime>	2354	to make sure you link against any libraries where the C<clock_gettime>
1778	function is hiding in (often F<-lrt>).	2355	function is hiding in (often F<-lrt>).
1779		2356
1780	=item EV_USE_REALTIME	2357	=item EV_USE_REALTIME
1781		2358
1782	If defined to be C<1>, libev will try to detect the availability of the	2359	If defined to be C<1>, libev will try to detect the availability of the
1783	realtime clock option at compiletime (and assume its availability at	2360	realtime clock option at compiletime (and assume its availability at
1784	runtime if successful). Otherwise no use of the realtime clock option will	2361	runtime if successful). Otherwise no use of the realtime clock option will
1785	be attempted. This effectively replaces C<gettimeofday> by C<clock_get	2362	be attempted. This effectively replaces C<gettimeofday> by C<clock_get
1786	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries	2363	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the
1787	in the description of C<EV_USE_MONOTONIC>, though.	2364	note about libraries in the description of C<EV_USE_MONOTONIC>, though.
		2365
		2366	=item EV_USE_NANOSLEEP
		2367
		2368	If defined to be C<1>, libev will assume that C<nanosleep ()> is available
		2369	and will use it for delays. Otherwise it will use C<select ()>.
1788		2370
1789	=item EV_USE_SELECT	2371	=item EV_USE_SELECT
1790		2372
1791	If undefined or defined to be C<1>, libev will compile in support for the	2373	If undefined or defined to be C<1>, libev will compile in support for the
1792	C<select>(2) backend. No attempt at autodetection will be done: if no	2374	C<select>(2) backend. No attempt at autodetection will be done: if no
…		…
1847		2429
1848	=item EV_USE_DEVPOLL	2430	=item EV_USE_DEVPOLL
1849		2431
1850	reserved for future expansion, works like the USE symbols above.	2432	reserved for future expansion, works like the USE symbols above.
1851		2433
		2434	=item EV_USE_INOTIFY
		2435
		2436	If defined to be C<1>, libev will compile in support for the Linux inotify
		2437	interface to speed up C<ev_stat> watchers. Its actual availability will
		2438	be detected at runtime.
		2439
1852	=item EV_H	2440	=item EV_H
1853		2441
1854	The name of the F<ev.h> header file used to include it. The default if	2442	The name of the F<ev.h> header file used to include it. The default if
1855	undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This	2443	undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This
1856	can be used to virtually rename the F<ev.h> header file in case of conflicts.	2444	can be used to virtually rename the F<ev.h> header file in case of conflicts.
…		…
1879	will have the C<struct ev_loop *> as first argument, and you can create	2467	will have the C<struct ev_loop *> as first argument, and you can create
1880	additional independent event loops. Otherwise there will be no support	2468	additional independent event loops. Otherwise there will be no support
1881	for multiple event loops and there is no first event loop pointer	2469	for multiple event loops and there is no first event loop pointer
1882	argument. Instead, all functions act on the single default loop.	2470	argument. Instead, all functions act on the single default loop.
1883		2471
		2472	=item EV_MINPRI
		2473
		2474	=item EV_MAXPRI
		2475
		2476	The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to
		2477	C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can
		2478	provide for more priorities by overriding those symbols (usually defined
		2479	to be C<-2> and C<2>, respectively).
		2480
		2481	When doing priority-based operations, libev usually has to linearly search
		2482	all the priorities, so having many of them (hundreds) uses a lot of space
		2483	and time, so using the defaults of five priorities (-2 .. +2) is usually
		2484	fine.
		2485
		2486	If your embedding app does not need any priorities, defining these both to
		2487	C<0> will save some memory and cpu.
		2488
1884	=item EV_PERIODIC_ENABLE	2489	=item EV_PERIODIC_ENABLE
1885		2490
1886	If undefined or defined to be C<1>, then periodic timers are supported. If	2491	If undefined or defined to be C<1>, then periodic timers are supported. If
1887	defined to be C<0>, then they are not. Disabling them saves a few kB of	2492	defined to be C<0>, then they are not. Disabling them saves a few kB of
1888	code.	2493	code.
1889		2494
		2495	=item EV_IDLE_ENABLE
		2496
		2497	If undefined or defined to be C<1>, then idle watchers are supported. If
		2498	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2499	code.
		2500
1890	=item EV_EMBED_ENABLE	2501	=item EV_EMBED_ENABLE
1891		2502
1892	If undefined or defined to be C<1>, then embed watchers are supported. If	2503	If undefined or defined to be C<1>, then embed watchers are supported. If
1893	defined to be C<0>, then they are not.	2504	defined to be C<0>, then they are not.
1894		2505
1895	=item EV_STAT_ENABLE	2506	=item EV_STAT_ENABLE
1896		2507
1897	If undefined or defined to be C<1>, then stat watchers are supported. If	2508	If undefined or defined to be C<1>, then stat watchers are supported. If
		2509	defined to be C<0>, then they are not.
		2510
		2511	=item EV_FORK_ENABLE
		2512
		2513	If undefined or defined to be C<1>, then fork watchers are supported. If
1898	defined to be C<0>, then they are not.	2514	defined to be C<0>, then they are not.
1899		2515
1900	=item EV_MINIMAL	2516	=item EV_MINIMAL
1901		2517
1902	If you need to shave off some kilobytes of code at the expense of some	2518	If you need to shave off some kilobytes of code at the expense of some
1903	speed, define this symbol to C<1>. Currently only used for gcc to override	2519	speed, define this symbol to C<1>. Currently only used for gcc to override
1904	some inlining decisions, saves roughly 30% codesize of amd64.	2520	some inlining decisions, saves roughly 30% codesize of amd64.
		2521
		2522	=item EV_PID_HASHSIZE
		2523
		2524	C<ev_child> watchers use a small hash table to distribute workload by
		2525	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
		2526	than enough. If you need to manage thousands of children you might want to
		2527	increase this value (I<must> be a power of two).
		2528
		2529	=item EV_INOTIFY_HASHSIZE
		2530
		2531	C<ev_stat> watchers use a small hash table to distribute workload by
		2532	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
		2533	usually more than enough. If you need to manage thousands of C<ev_stat>
		2534	watchers you might want to increase this value (I<must> be a power of
		2535	two).
1905		2536
1906	=item EV_COMMON	2537	=item EV_COMMON
1907		2538
1908	By default, all watchers have a C<void *data> member. By redefining	2539	By default, all watchers have a C<void *data> member. By redefining
1909	this macro to a something else you can include more and other types of	2540	this macro to a something else you can include more and other types of
…		…
1922		2553
1923	=item ev_set_cb (ev, cb)	2554	=item ev_set_cb (ev, cb)
1924		2555
1925	Can be used to change the callback member declaration in each watcher,	2556	Can be used to change the callback member declaration in each watcher,
1926	and the way callbacks are invoked and set. Must expand to a struct member	2557	and the way callbacks are invoked and set. Must expand to a struct member
1927	definition and a statement, respectively. See the F<ev.v> header file for	2558	definition and a statement, respectively. See the F<ev.h> header file for
1928	their default definitions. One possible use for overriding these is to	2559	their default definitions. One possible use for overriding these is to
1929	avoid the C<struct ev_loop *> as first argument in all cases, or to use	2560	avoid the C<struct ev_loop *> as first argument in all cases, or to use
1930	method calls instead of plain function calls in C++.	2561	method calls instead of plain function calls in C++.
		2562
		2563	=head2 EXPORTED API SYMBOLS
		2564
		2565	If you need to re-export the API (e.g. via a dll) and you need a list of
		2566	exported symbols, you can use the provided F<Symbol.*> files which list
		2567	all public symbols, one per line:
		2568
		2569	Symbols.ev for libev proper
		2570	Symbols.event for the libevent emulation
		2571
		2572	This can also be used to rename all public symbols to avoid clashes with
		2573	multiple versions of libev linked together (which is obviously bad in
		2574	itself, but sometimes it is inconvinient to avoid this).
		2575
		2576	A sed command like this will create wrapper C<#define>'s that you need to
		2577	include before including F<ev.h>:
		2578
		2579	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h
		2580
		2581	This would create a file F<wrap.h> which essentially looks like this:
		2582
		2583	#define ev_backend myprefix_ev_backend
		2584	#define ev_check_start myprefix_ev_check_start
		2585	#define ev_check_stop myprefix_ev_check_stop
		2586	...
1931		2587
1932	=head2 EXAMPLES	2588	=head2 EXAMPLES
1933		2589
1934	For a real-world example of a program the includes libev	2590	For a real-world example of a program the includes libev
1935	verbatim, you can have a look at the EV perl module	2591	verbatim, you can have a look at the EV perl module
…		…
1938	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file	2594	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file
1939	will be compiled. It is pretty complex because it provides its own header	2595	will be compiled. It is pretty complex because it provides its own header
1940	file.	2596	file.
1941		2597
1942	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	2598	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
1943	that everybody includes and which overrides some autoconf choices:	2599	that everybody includes and which overrides some configure choices:
1944		2600
		2601	#define EV_MINIMAL 1
1945	#define EV_USE_POLL 0	2602	#define EV_USE_POLL 0
1946	#define EV_MULTIPLICITY 0	2603	#define EV_MULTIPLICITY 0
1947	#define EV_PERIODICS 0	2604	#define EV_PERIODIC_ENABLE 0
		2605	#define EV_STAT_ENABLE 0
		2606	#define EV_FORK_ENABLE 0
1948	#define EV_CONFIG_H <config.h>	2607	#define EV_CONFIG_H <config.h>
		2608	#define EV_MINPRI 0
		2609	#define EV_MAXPRI 0
1949		2610
1950	#include "ev++.h"	2611	#include "ev++.h"
1951		2612
1952	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	2613	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
1953		2614
…		…
1959		2620
1960	In this section the complexities of (many of) the algorithms used inside	2621	In this section the complexities of (many of) the algorithms used inside
1961	libev will be explained. For complexity discussions about backends see the	2622	libev will be explained. For complexity discussions about backends see the
1962	documentation for C<ev_default_init>.	2623	documentation for C<ev_default_init>.
1963		2624
		2625	All of the following are about amortised time: If an array needs to be
		2626	extended, libev needs to realloc and move the whole array, but this
		2627	happens asymptotically never with higher number of elements, so O(1) might
		2628	mean it might do a lengthy realloc operation in rare cases, but on average
		2629	it is much faster and asymptotically approaches constant time.
		2630
1964	=over 4	2631	=over 4
1965		2632
1966	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)	2633	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
1967		2634
		2635	This means that, when you have a watcher that triggers in one hour and
		2636	there are 100 watchers that would trigger before that then inserting will
		2637	have to skip roughly seven (C<ld 100>) of these watchers.
		2638
1968	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)	2639	=item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers)
		2640
		2641	That means that changing a timer costs less than removing/adding them
		2642	as only the relative motion in the event queue has to be paid for.
1969		2643
1970	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2644	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
1971		2645
		2646	These just add the watcher into an array or at the head of a list.
		2647
1972	=item Stopping check/prepare/idle watchers: O(1)	2648	=item Stopping check/prepare/idle watchers: O(1)
1973		2649
1974	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))	2650	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
1975		2651
		2652	These watchers are stored in lists then need to be walked to find the
		2653	correct watcher to remove. The lists are usually short (you don't usually
		2654	have many watchers waiting for the same fd or signal).
		2655
1976	=item Finding the next timer per loop iteration: O(1)	2656	=item Finding the next timer in each loop iteration: O(1)
		2657
		2658	By virtue of using a binary heap, the next timer is always found at the
		2659	beginning of the storage array.
1977		2660
1978	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	2661	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
1979		2662
1980	=item Activating one watcher: O(1)	2663	A change means an I/O watcher gets started or stopped, which requires
		2664	libev to recalculate its status (and possibly tell the kernel, depending
		2665	on backend and wether C<ev_io_set> was used).
		2666
		2667	=item Activating one watcher (putting it into the pending state): O(1)
		2668
		2669	=item Priority handling: O(number_of_priorities)
		2670
		2671	Priorities are implemented by allocating some space for each
		2672	priority. When doing priority-based operations, libev usually has to
		2673	linearly search all the priorities, but starting/stopping and activating
		2674	watchers becomes O(1) w.r.t. prioritiy handling.
1981		2675
1982	=back	2676	=back
1983		2677
1984		2678
1985	=head1 AUTHOR	2679	=head1 AUTHOR

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