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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
		104	component C<stamp> might indicate, it is also used for time differences
		105	throughout libev.
52		106
53	=head1 GLOBAL FUNCTIONS	107	=head1 GLOBAL FUNCTIONS
54		108
55	These functions can be called anytime, even before initialising the	109	These functions can be called anytime, even before initialising the
56	library in any way.	110	library in any way.
…		…
61		115
62	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
63	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
64	you actually want to know.	118	you actually want to know.
65		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
66	=item int ev_version_major ()	126	=item int ev_version_major ()
67		127
68	=item int ev_version_minor ()	128	=item int ev_version_minor ()
69		129
70	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
71	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
72	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
73	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
74	version of the library your program was compiled against.	134	version of the library your program was compiled against.
75		135
		136	These version numbers refer to the ABI version of the library, not the
		137	release version.
		138
76	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,
77	as this indicates an incompatible change. Minor versions are usually	140	as this indicates an incompatible change. Minor versions are usually
78	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
79	not a problem.	142	not a problem.
80		143
81	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
82	version:	145	version.
83		146
84	assert (("libev version mismatch",	147	assert (("libev version mismatch",
85	ev_version_major () == EV_VERSION_MAJOR	148	ev_version_major () == EV_VERSION_MAJOR
86	&& ev_version_minor () >= EV_VERSION_MINOR));	149	&& ev_version_minor () >= EV_VERSION_MINOR));
87		150
…		…
117		180
118	See the description of C<ev_embed> watchers for more info.	181	See the description of C<ev_embed> watchers for more info.
119		182
120	=item ev_set_allocator (void *(*cb)(void *ptr, long size))	183	=item ev_set_allocator (void *(*cb)(void *ptr, long size))
121		184
122	Sets the allocation function to use (the prototype is similar to the	185	Sets the allocation function to use (the prototype is similar - the
123	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
124	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
125	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
126	destructive action. The default is your system realloc function.	189	potentially destructive action. The default is your system realloc
		190	function.
127		191
128	You could override this function in high-availability programs to, say,	192	You could override this function in high-availability programs to, say,
129	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,
130	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.
131		195
132	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
133	retries: better than mine).	197	retries).
134		198
135	static void *	199	static void *
136	persistent_realloc (void *ptr, long size)	200	persistent_realloc (void *ptr, size_t size)
137	{	201	{
138	for (;;)	202	for (;;)
139	{	203	{
140	void *newptr = realloc (ptr, size);	204	void *newptr = realloc (ptr, size);
141		205
…		…
157	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
158	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
159	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
160	(such as abort).	224	(such as abort).
161		225
162	Example: do the same thing as libev does internally:	226	Example: This is basically the same thing that libev does internally, too.
163		227
164	static void	228	static void
165	fatal_error (const char *msg)	229	fatal_error (const char *msg)
166	{	230	{
167	perror (msg);	231	perror (msg);
…		…
217	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	281	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
218	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
219	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
220	around bugs.	284	around bugs.
221		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
222	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	306	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
223		307
224	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
225	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,
226	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
227	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
228	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.
229		320
230	=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)
231		322
232	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
233	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
234	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
235	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.
236		329
237	=item C<EVBACKEND_EPOLL> (value 4, Linux)	330	=item C<EVBACKEND_EPOLL> (value 4, Linux)
238		331
239	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,
240	but it scales phenomenally better. While poll and select usually scale like	333	but it scales phenomenally better. While poll and select usually scale
241	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),
242	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.
243		339
244	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
245	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
246	(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
247	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
248	well if you register events for both fds.	344	very well if you register events for both fds.
249		345
250	Please note that epoll sometimes generates spurious notifications, so you	346	Please note that epoll sometimes generates spurious notifications, so you
251	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
252	(or space) is available.	348	(or space) is available.
253		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
254	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)	357	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)
255		358
256	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
257	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
258	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
259	completely useless). For this reason its not being "autodetected"	362	it's completely useless). For this reason it's not being "autodetected"
260	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
261	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.
262		370
263	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
264	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
265	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
266	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
267	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.
268		386
269	=item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8)	387	=item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8)
270		388
271	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.
272		393
273	=item C<EVBACKEND_PORT> (value 32, Solaris 10)	394	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
274		395
275	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,
276	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)).
277		398
278	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
279	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
280	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.
281		407
282	=item C<EVBACKEND_ALL>	408	=item C<EVBACKEND_ALL>
283		409
284	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
285	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
286	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.	412	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.
		413
		414	It is definitely not recommended to use this flag.
287		415
288	=back	416	=back
289		417
290	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
291	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
…		…
313	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
314	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
315	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
316	undefined behaviour (or a failed assertion if assertions are enabled).	444	undefined behaviour (or a failed assertion if assertions are enabled).
317		445
318	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.
319		447
320	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	448	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
321	if (!epoller)	449	if (!epoller)
322	fatal ("no epoll found here, maybe it hides under your chair");	450	fatal ("no epoll found here, maybe it hides under your chair");
323		451
…		…
326	Destroys the default loop again (frees all memory and kernel state	454	Destroys the default loop again (frees all memory and kernel state
327	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
328	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
329	responsibility to either stop all watchers cleanly yoursef I<before>	457	responsibility to either stop all watchers cleanly yoursef I<before>
330	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
331	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
332	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>).
333		470
334	=item ev_loop_destroy (loop)	471	=item ev_loop_destroy (loop)
335		472
336	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
337	earlier call to C<ev_loop_new>.	474	earlier call to C<ev_loop_new>.
…		…
361		498
362	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
363	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
364	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.
365		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
366	=item unsigned int ev_backend (loop)	513	=item unsigned int ev_backend (loop)
367		514
368	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
369	use.	516	use.
370		517
…		…
372		519
373	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
374	received events and started processing them. This timestamp does not	521	received events and started processing them. This timestamp does not
375	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
376	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
377	event occuring (or more correctly, libev finding out about it).	524	event occurring (or more correctly, libev finding out about it).
378		525
379	=item ev_loop (loop, int flags)	526	=item ev_loop (loop, int flags)
380		527
381	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
382	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
…		…
403	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
404	usually a better approach for this kind of thing.	551	usually a better approach for this kind of thing.
405		552
406	Here are the gory details of what C<ev_loop> does:	553	Here are the gory details of what C<ev_loop> does:
407		554
		555	- Before the first iteration, call any pending watchers.
408	* If there are no active watchers (reference count is zero), return.	556	* If there are no active watchers (reference count is zero), return.
409	- Queue prepare watchers and then call all outstanding watchers.	557	- Queue all prepare watchers and then call all outstanding watchers.
410	- If we have been forked, recreate the kernel state.	558	- If we have been forked, recreate the kernel state.
411	- Update the kernel state with all outstanding changes.	559	- Update the kernel state with all outstanding changes.
412	- Update the "event loop time".	560	- Update the "event loop time".
413	- Calculate for how long to block.	561	- Calculate for how long to block.
414	- Block the process, waiting for any events.	562	- Block the process, waiting for any events.
…		…
422	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
423	be handled here by queueing them when their watcher gets executed.	571	be handled here by queueing them when their watcher gets executed.
424	- 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
425	were used, return, otherwise continue with step *.	573	were used, return, otherwise continue with step *.
426		574
427	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
428	anymore.	576	anymore.
429		577
430	... queue jobs here, make sure they register event watchers as long	578	... queue jobs here, make sure they register event watchers as long
431	... 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..)
432	ev_loop (my_loop, 0);	580	ev_loop (my_loop, 0);
…		…
452	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
453	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
454	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
455	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>.
456		604
457	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>
458	running when nothing else is active.	606	running when nothing else is active.
459		607
460	struct dv_signal exitsig;	608	struct ev_signal exitsig;
461	ev_signal_init (&exitsig, sig_cb, SIGINT);	609	ev_signal_init (&exitsig, sig_cb, SIGINT);
462	ev_signal_start (myloop, &exitsig);	610	ev_signal_start (loop, &exitsig);
463	evf_unref (myloop);	611	evf_unref (loop);
464		612
465	Example: for some weird reason, unregister the above signal handler again.	613	Example: For some weird reason, unregister the above signal handler again.
466		614
467	ev_ref (myloop);	615	ev_ref (loop);
468	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.
469		653
470	=back	654	=back
471		655
472		656
473	=head1 ANATOMY OF A WATCHER	657	=head1 ANATOMY OF A WATCHER
…		…
653	=item bool ev_is_pending (ev_TYPE *watcher)	837	=item bool ev_is_pending (ev_TYPE *watcher)
654		838
655	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
656	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
657	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
658	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
659	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).
660		845
661	=item callback = ev_cb (ev_TYPE *watcher)	846	=item callback ev_cb (ev_TYPE *watcher)
662		847
663	Returns the callback currently set on the watcher.	848	Returns the callback currently set on the watcher.
664		849
665	=item ev_cb_set (ev_TYPE *watcher, callback)	850	=item ev_cb_set (ev_TYPE *watcher, callback)
666		851
667	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
668	(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>.
669		894
670	=back	895	=back
671		896
672		897
673	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	898	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
694	{	919	{
695	struct my_io *w = (struct my_io *)w_;	920	struct my_io *w = (struct my_io *)w_;
696	...	921	...
697	}	922	}
698		923
699	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
700	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	}
701		955
702		956
703	=head1 WATCHER TYPES	957	=head1 WATCHER TYPES
704		958
705	This section describes each watcher in detail, but will not repeat	959	This section describes each watcher in detail, but will not repeat
…		…
729	In general you can register as many read and/or write event watchers per	983	In general you can register as many read and/or write event watchers per
730	fd as you want (as long as you don't confuse yourself). Setting all file	984	fd as you want (as long as you don't confuse yourself). Setting all file
731	descriptors to non-blocking mode is also usually a good idea (but not	985	descriptors to non-blocking mode is also usually a good idea (but not
732	required if you know what you are doing).	986	required if you know what you are doing).
733		987
734	You have to be careful with dup'ed file descriptors, though. Some backends
735	(the linux epoll backend is a notable example) cannot handle dup'ed file
736	descriptors correctly if you register interest in two or more fds pointing
737	to the same underlying file/socket/etc. description (that is, they share
738	the same underlying "file open").
739
740	If you must do this, then force the use of a known-to-be-good backend	988	If you must do this, then force the use of a known-to-be-good backend
741	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and	989	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and
742	C<EVBACKEND_POLL>).	990	C<EVBACKEND_POLL>).
743		991
744	Another thing you have to watch out for is that it is quite easy to	992	Another thing you have to watch out for is that it is quite easy to
…		…
750	it is best to always use non-blocking I/O: An extra C<read>(2) returning	998	it is best to always use non-blocking I/O: An extra C<read>(2) returning
751	C<EAGAIN> is far preferable to a program hanging until some data arrives.	999	C<EAGAIN> is far preferable to a program hanging until some data arrives.
752		1000
753	If you cannot run the fd in non-blocking mode (for example you should not	1001	If you cannot run the fd in non-blocking mode (for example you should not
754	play around with an Xlib connection), then you have to seperately re-test	1002	play around with an Xlib connection), then you have to seperately re-test
755	wether a file descriptor is really ready with a known-to-be good interface	1003	whether a file descriptor is really ready with a known-to-be good interface
756	such as poll (fortunately in our Xlib example, Xlib already does this on	1004	such as poll (fortunately in our Xlib example, Xlib already does this on
757	its own, so its quite safe to use).	1005	its own, so its quite safe to use).
		1006
		1007	=head3 The special problem of disappearing file descriptors
		1008
		1009	Some backends (e.g. kqueue, epoll) need to be told about closing a file
		1010	descriptor (either by calling C<close> explicitly or by any other means,
		1011	such as C<dup>). The reason is that you register interest in some file
		1012	descriptor, but when it goes away, the operating system will silently drop
		1013	this interest. If another file descriptor with the same number then is
		1014	registered with libev, there is no efficient way to see that this is, in
		1015	fact, a different file descriptor.
		1016
		1017	To avoid having to explicitly tell libev about such cases, libev follows
		1018	the following policy: Each time C<ev_io_set> is being called, libev
		1019	will assume that this is potentially a new file descriptor, otherwise
		1020	it is assumed that the file descriptor stays the same. That means that
		1021	you I<have> to call C<ev_io_set> (or C<ev_io_init>) when you change the
		1022	descriptor even if the file descriptor number itself did not change.
		1023
		1024	This is how one would do it normally anyway, the important point is that
		1025	the libev application should not optimise around libev but should leave
		1026	optimisations to libev.
		1027
		1028	=head3 The special problem of dup'ed file descriptors
		1029
		1030	Some backends (e.g. epoll), cannot register events for file descriptors,
		1031	but only events for the underlying file descriptions. That means when you
		1032	have C<dup ()>'ed file descriptors or weirder constellations, and register
		1033	events for them, only one file descriptor might actually receive events.
		1034
		1035	There is no workaround possible except not registering events
		1036	for potentially C<dup ()>'ed file descriptors, or to resort to
		1037	C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>.
		1038
		1039	=head3 The special problem of fork
		1040
		1041	Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit
		1042	useless behaviour. Libev fully supports fork, but needs to be told about
		1043	it in the child.
		1044
		1045	To support fork in your programs, you either have to call
		1046	C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child,
		1047	enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or
		1048	C<EVBACKEND_POLL>.
		1049
		1050
		1051	=head3 Watcher-Specific Functions
758		1052
759	=over 4	1053	=over 4
760		1054
761	=item ev_io_init (ev_io *, callback, int fd, int events)	1055	=item ev_io_init (ev_io *, callback, int fd, int events)
762		1056
…		…
774		1068
775	The events being watched.	1069	The events being watched.
776		1070
777	=back	1071	=back
778		1072
779	Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well	1073	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well
780	readable, but only once. Since it is likely line-buffered, you could	1074	readable, but only once. Since it is likely line-buffered, you could
781	attempt to read a whole line in the callback:	1075	attempt to read a whole line in the callback.
782		1076
783	static void	1077	static void
784	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1078	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
785	{	1079	{
786	ev_io_stop (loop, w);	1080	ev_io_stop (loop, w);
…		…
816		1110
817	The callback is guarenteed to be invoked only when its timeout has passed,	1111	The callback is guarenteed to be invoked only when its timeout has passed,
818	but if multiple timers become ready during the same loop iteration then	1112	but if multiple timers become ready during the same loop iteration then
819	order of execution is undefined.	1113	order of execution is undefined.
820		1114
		1115	=head3 Watcher-Specific Functions and Data Members
		1116
821	=over 4	1117	=over 4
822		1118
823	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	1119	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
824		1120
825	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)	1121	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)
…		…
838	=item ev_timer_again (loop)	1134	=item ev_timer_again (loop)
839		1135
840	This will act as if the timer timed out and restart it again if it is	1136	This will act as if the timer timed out and restart it again if it is
841	repeating. The exact semantics are:	1137	repeating. The exact semantics are:
842		1138
		1139	If the timer is pending, its pending status is cleared.
		1140
843	If the timer is started but nonrepeating, stop it.	1141	If the timer is started but nonrepeating, stop it (as if it timed out).
844		1142
845	If the timer is repeating, either start it if necessary (with the repeat	1143	If the timer is repeating, either start it if necessary (with the
846	value), or reset the running timer to the repeat value.	1144	C<repeat> value), or reset the running timer to the C<repeat> value.
847		1145
848	This sounds a bit complicated, but here is a useful and typical	1146	This sounds a bit complicated, but here is a useful and typical
849	example: Imagine you have a tcp connection and you want a so-called	1147	example: Imagine you have a tcp connection and you want a so-called idle
850	idle timeout, that is, you want to be called when there have been,	1148	timeout, that is, you want to be called when there have been, say, 60
851	say, 60 seconds of inactivity on the socket. The easiest way to do	1149	seconds of inactivity on the socket. The easiest way to do this is to
852	this is to configure an C<ev_timer> with C<after>=C<repeat>=C<60> and calling	1150	configure an C<ev_timer> with a C<repeat> value of C<60> and then call
853	C<ev_timer_again> each time you successfully read or write some data. If	1151	C<ev_timer_again> each time you successfully read or write some data. If
854	you go into an idle state where you do not expect data to travel on the	1152	you go into an idle state where you do not expect data to travel on the
855	socket, you can stop the timer, and again will automatically restart it if	1153	socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will
856	need be.	1154	automatically restart it if need be.
857		1155
858	You can also ignore the C<after> value and C<ev_timer_start> altogether	1156	That means you can ignore the C<after> value and C<ev_timer_start>
859	and only ever use the C<repeat> value:	1157	altogether and only ever use the C<repeat> value and C<ev_timer_again>:
860		1158
861	ev_timer_init (timer, callback, 0., 5.);	1159	ev_timer_init (timer, callback, 0., 5.);
862	ev_timer_again (loop, timer);	1160	ev_timer_again (loop, timer);
863	...	1161	...
864	timer->again = 17.;	1162	timer->again = 17.;
865	ev_timer_again (loop, timer);	1163	ev_timer_again (loop, timer);
866	...	1164	...
867	timer->again = 10.;	1165	timer->again = 10.;
868	ev_timer_again (loop, timer);	1166	ev_timer_again (loop, timer);
869		1167
870	This is more efficient then stopping/starting the timer eahc time you want	1168	This is more slightly efficient then stopping/starting the timer each time
871	to modify its timeout value.	1169	you want to modify its timeout value.
872		1170
873	=item ev_tstamp repeat [read-write]	1171	=item ev_tstamp repeat [read-write]
874		1172
875	The current C<repeat> value. Will be used each time the watcher times out	1173	The current C<repeat> value. Will be used each time the watcher times out
876	or C<ev_timer_again> is called and determines the next timeout (if any),	1174	or C<ev_timer_again> is called and determines the next timeout (if any),
877	which is also when any modifications are taken into account.	1175	which is also when any modifications are taken into account.
878		1176
879	=back	1177	=back
880		1178
881	Example: create a timer that fires after 60 seconds.	1179	Example: Create a timer that fires after 60 seconds.
882		1180
883	static void	1181	static void
884	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1182	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
885	{	1183	{
886	.. one minute over, w is actually stopped right here	1184	.. one minute over, w is actually stopped right here
…		…
888		1186
889	struct ev_timer mytimer;	1187	struct ev_timer mytimer;
890	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1188	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
891	ev_timer_start (loop, &mytimer);	1189	ev_timer_start (loop, &mytimer);
892		1190
893	Example: create a timeout timer that times out after 10 seconds of	1191	Example: Create a timeout timer that times out after 10 seconds of
894	inactivity.	1192	inactivity.
895		1193
896	static void	1194	static void
897	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1195	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
898	{	1196	{
…		…
918	but on wallclock time (absolute time). You can tell a periodic watcher	1216	but on wallclock time (absolute time). You can tell a periodic watcher
919	to trigger "at" some specific point in time. For example, if you tell a	1217	to trigger "at" some specific point in time. For example, if you tell a
920	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()	1218	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()
921	+ 10.>) and then reset your system clock to the last year, then it will	1219	+ 10.>) and then reset your system clock to the last year, then it will
922	take a year to trigger the event (unlike an C<ev_timer>, which would trigger	1220	take a year to trigger the event (unlike an C<ev_timer>, which would trigger
923	roughly 10 seconds later and of course not if you reset your system time	1221	roughly 10 seconds later).
924	again).
925		1222
926	They can also be used to implement vastly more complex timers, such as	1223	They can also be used to implement vastly more complex timers, such as
927	triggering an event on eahc midnight, local time.	1224	triggering an event on each midnight, local time or other, complicated,
		1225	rules.
928		1226
929	As with timers, the callback is guarenteed to be invoked only when the	1227	As with timers, the callback is guarenteed to be invoked only when the
930	time (C<at>) has been passed, but if multiple periodic timers become ready	1228	time (C<at>) has been passed, but if multiple periodic timers become ready
931	during the same loop iteration then order of execution is undefined.	1229	during the same loop iteration then order of execution is undefined.
932		1230
		1231	=head3 Watcher-Specific Functions and Data Members
		1232
933	=over 4	1233	=over 4
934		1234
935	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)	1235	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)
936		1236
937	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)	1237	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)
…		…
939	Lots of arguments, lets sort it out... There are basically three modes of	1239	Lots of arguments, lets sort it out... There are basically three modes of
940	operation, and we will explain them from simplest to complex:	1240	operation, and we will explain them from simplest to complex:
941		1241
942	=over 4	1242	=over 4
943		1243
944	=item * absolute timer (interval = reschedule_cb = 0)	1244	=item * absolute timer (at = time, interval = reschedule_cb = 0)
945		1245
946	In this configuration the watcher triggers an event at the wallclock time	1246	In this configuration the watcher triggers an event at the wallclock time
947	C<at> and doesn't repeat. It will not adjust when a time jump occurs,	1247	C<at> and doesn't repeat. It will not adjust when a time jump occurs,
948	that is, if it is to be run at January 1st 2011 then it will run when the	1248	that is, if it is to be run at January 1st 2011 then it will run when the
949	system time reaches or surpasses this time.	1249	system time reaches or surpasses this time.
950		1250
951	=item * non-repeating interval timer (interval > 0, reschedule_cb = 0)	1251	=item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
952		1252
953	In this mode the watcher will always be scheduled to time out at the next	1253	In this mode the watcher will always be scheduled to time out at the next
954	C<at + N * interval> time (for some integer N) and then repeat, regardless	1254	C<at + N * interval> time (for some integer N, which can also be negative)
955	of any time jumps.	1255	and then repeat, regardless of any time jumps.
956		1256
957	This can be used to create timers that do not drift with respect to system	1257	This can be used to create timers that do not drift with respect to system
958	time:	1258	time:
959		1259
960	ev_periodic_set (&periodic, 0., 3600., 0);	1260	ev_periodic_set (&periodic, 0., 3600., 0);
…		…
966		1266
967	Another way to think about it (for the mathematically inclined) is that	1267	Another way to think about it (for the mathematically inclined) is that
968	C<ev_periodic> will try to run the callback in this mode at the next possible	1268	C<ev_periodic> will try to run the callback in this mode at the next possible
969	time where C<time = at (mod interval)>, regardless of any time jumps.	1269	time where C<time = at (mod interval)>, regardless of any time jumps.
970		1270
		1271	For numerical stability it is preferable that the C<at> value is near
		1272	C<ev_now ()> (the current time), but there is no range requirement for
		1273	this value.
		1274
971	=item * manual reschedule mode (reschedule_cb = callback)	1275	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
972		1276
973	In this mode the values for C<interval> and C<at> are both being	1277	In this mode the values for C<interval> and C<at> are both being
974	ignored. Instead, each time the periodic watcher gets scheduled, the	1278	ignored. Instead, each time the periodic watcher gets scheduled, the
975	reschedule callback will be called with the watcher as first, and the	1279	reschedule callback will be called with the watcher as first, and the
976	current time as second argument.	1280	current time as second argument.
977		1281
978	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,	1282	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,
979	ever, or make any event loop modifications>. If you need to stop it,	1283	ever, or make any event loop modifications>. If you need to stop it,
980	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by	1284	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by
981	starting a prepare watcher).	1285	starting an C<ev_prepare> watcher, which is legal).
982		1286
983	Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w,	1287	Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w,
984	ev_tstamp now)>, e.g.:	1288	ev_tstamp now)>, e.g.:
985		1289
986	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	1290	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
…		…
1009	Simply stops and restarts the periodic watcher again. This is only useful	1313	Simply stops and restarts the periodic watcher again. This is only useful
1010	when you changed some parameters or the reschedule callback would return	1314	when you changed some parameters or the reschedule callback would return
1011	a different time than the last time it was called (e.g. in a crond like	1315	a different time than the last time it was called (e.g. in a crond like
1012	program when the crontabs have changed).	1316	program when the crontabs have changed).
1013		1317
		1318	=item ev_tstamp offset [read-write]
		1319
		1320	When repeating, this contains the offset value, otherwise this is the
		1321	absolute point in time (the C<at> value passed to C<ev_periodic_set>).
		1322
		1323	Can be modified any time, but changes only take effect when the periodic
		1324	timer fires or C<ev_periodic_again> is being called.
		1325
1014	=item ev_tstamp interval [read-write]	1326	=item ev_tstamp interval [read-write]
1015		1327
1016	The current interval value. Can be modified any time, but changes only	1328	The current interval value. Can be modified any time, but changes only
1017	take effect when the periodic timer fires or C<ev_periodic_again> is being	1329	take effect when the periodic timer fires or C<ev_periodic_again> is being
1018	called.	1330	called.
…		…
1021		1333
1022	The current reschedule callback, or C<0>, if this functionality is	1334	The current reschedule callback, or C<0>, if this functionality is
1023	switched off. Can be changed any time, but changes only take effect when	1335	switched off. Can be changed any time, but changes only take effect when
1024	the periodic timer fires or C<ev_periodic_again> is being called.	1336	the periodic timer fires or C<ev_periodic_again> is being called.
1025		1337
		1338	=item ev_tstamp at [read-only]
		1339
		1340	When active, contains the absolute time that the watcher is supposed to
		1341	trigger next.
		1342
1026	=back	1343	=back
1027		1344
1028	Example: call a callback every hour, or, more precisely, whenever the	1345	Example: Call a callback every hour, or, more precisely, whenever the
1029	system clock is divisible by 3600. The callback invocation times have	1346	system clock is divisible by 3600. The callback invocation times have
1030	potentially a lot of jittering, but good long-term stability.	1347	potentially a lot of jittering, but good long-term stability.
1031		1348
1032	static void	1349	static void
1033	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1350	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)
…		…
1037		1354
1038	struct ev_periodic hourly_tick;	1355	struct ev_periodic hourly_tick;
1039	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1356	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1040	ev_periodic_start (loop, &hourly_tick);	1357	ev_periodic_start (loop, &hourly_tick);
1041		1358
1042	Example: the same as above, but use a reschedule callback to do it:	1359	Example: The same as above, but use a reschedule callback to do it:
1043		1360
1044	#include <math.h>	1361	#include <math.h>
1045		1362
1046	static ev_tstamp	1363	static ev_tstamp
1047	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1364	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
…		…
1049	return fmod (now, 3600.) + 3600.;	1366	return fmod (now, 3600.) + 3600.;
1050	}	1367	}
1051		1368
1052	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1369	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1053		1370
1054	Example: call a callback every hour, starting now:	1371	Example: Call a callback every hour, starting now:
1055		1372
1056	struct ev_periodic hourly_tick;	1373	struct ev_periodic hourly_tick;
1057	ev_periodic_init (&hourly_tick, clock_cb,	1374	ev_periodic_init (&hourly_tick, clock_cb,
1058	fmod (ev_now (loop), 3600.), 3600., 0);	1375	fmod (ev_now (loop), 3600.), 3600., 0);
1059	ev_periodic_start (loop, &hourly_tick);	1376	ev_periodic_start (loop, &hourly_tick);
…		…
1071	with the kernel (thus it coexists with your own signal handlers as long	1388	with the kernel (thus it coexists with your own signal handlers as long
1072	as you don't register any with libev). Similarly, when the last signal	1389	as you don't register any with libev). Similarly, when the last signal
1073	watcher for a signal is stopped libev will reset the signal handler to	1390	watcher for a signal is stopped libev will reset the signal handler to
1074	SIG_DFL (regardless of what it was set to before).	1391	SIG_DFL (regardless of what it was set to before).
1075		1392
		1393	=head3 Watcher-Specific Functions and Data Members
		1394
1076	=over 4	1395	=over 4
1077		1396
1078	=item ev_signal_init (ev_signal *, callback, int signum)	1397	=item ev_signal_init (ev_signal *, callback, int signum)
1079		1398
1080	=item ev_signal_set (ev_signal *, int signum)	1399	=item ev_signal_set (ev_signal *, int signum)
…		…
1091		1410
1092	=head2 C<ev_child> - watch out for process status changes	1411	=head2 C<ev_child> - watch out for process status changes
1093		1412
1094	Child watchers trigger when your process receives a SIGCHLD in response to	1413	Child watchers trigger when your process receives a SIGCHLD in response to
1095	some child status changes (most typically when a child of yours dies).	1414	some child status changes (most typically when a child of yours dies).
		1415
		1416	=head3 Watcher-Specific Functions and Data Members
1096		1417
1097	=over 4	1418	=over 4
1098		1419
1099	=item ev_child_init (ev_child *, callback, int pid)	1420	=item ev_child_init (ev_child *, callback, int pid)
1100		1421
…		…
1120	The process exit/trace status caused by C<rpid> (see your systems	1441	The process exit/trace status caused by C<rpid> (see your systems
1121	C<waitpid> and C<sys/wait.h> documentation for details).	1442	C<waitpid> and C<sys/wait.h> documentation for details).
1122		1443
1123	=back	1444	=back
1124		1445
1125	Example: try to exit cleanly on SIGINT and SIGTERM.	1446	Example: Try to exit cleanly on SIGINT and SIGTERM.
1126		1447
1127	static void	1448	static void
1128	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)	1449	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1129	{	1450	{
1130	ev_unloop (loop, EVUNLOOP_ALL);	1451	ev_unloop (loop, EVUNLOOP_ALL);
…		…
1145	not exist" is a status change like any other. The condition "path does	1466	not exist" is a status change like any other. The condition "path does
1146	not exist" is signified by the C<st_nlink> field being zero (which is	1467	not exist" is signified by the C<st_nlink> field being zero (which is
1147	otherwise always forced to be at least one) and all the other fields of	1468	otherwise always forced to be at least one) and all the other fields of
1148	the stat buffer having unspecified contents.	1469	the stat buffer having unspecified contents.
1149		1470
		1471	The path I<should> be absolute and I<must not> end in a slash. If it is
		1472	relative and your working directory changes, the behaviour is undefined.
		1473
1150	Since there is no standard to do this, the portable implementation simply	1474	Since there is no standard to do this, the portable implementation simply
1151	calls C<stat (2)> regulalry on the path to see if it changed somehow. You	1475	calls C<stat (2)> regularly on the path to see if it changed somehow. You
1152	can specify a recommended polling interval for this case. If you specify	1476	can specify a recommended polling interval for this case. If you specify
1153	a polling interval of C<0> (highly recommended!) then a I<suitable,	1477	a polling interval of C<0> (highly recommended!) then a I<suitable,
1154	unspecified default> value will be used (which you can expect to be around	1478	unspecified default> value will be used (which you can expect to be around
1155	five seconds, although this might change dynamically). Libev will also	1479	five seconds, although this might change dynamically). Libev will also
1156	impose a minimum interval which is currently around C<0.1>, but thats	1480	impose a minimum interval which is currently around C<0.1>, but thats
…		…
1158		1482
1159	This watcher type is not meant for massive numbers of stat watchers,	1483	This watcher type is not meant for massive numbers of stat watchers,
1160	as even with OS-supported change notifications, this can be	1484	as even with OS-supported change notifications, this can be
1161	resource-intensive.	1485	resource-intensive.
1162		1486
1163	At the time of this writing, no specific OS backends are implemented, but	1487	At the time of this writing, only the Linux inotify interface is
1164	if demand increases, at least a kqueue and inotify backend will be added.	1488	implemented (implementing kqueue support is left as an exercise for the
		1489	reader). Inotify will be used to give hints only and should not change the
		1490	semantics of C<ev_stat> watchers, which means that libev sometimes needs
		1491	to fall back to regular polling again even with inotify, but changes are
		1492	usually detected immediately, and if the file exists there will be no
		1493	polling.
		1494
		1495	=head3 Inotify
		1496
		1497	When C<inotify (7)> support has been compiled into libev (generally only
		1498	available on Linux) and present at runtime, it will be used to speed up
		1499	change detection where possible. The inotify descriptor will be created lazily
		1500	when the first C<ev_stat> watcher is being started.
		1501
		1502	Inotify presense does not change the semantics of C<ev_stat> watchers
		1503	except that changes might be detected earlier, and in some cases, to avoid
		1504	making regular C<stat> calls. Even in the presense of inotify support
		1505	there are many cases where libev has to resort to regular C<stat> polling.
		1506
		1507	(There is no support for kqueue, as apparently it cannot be used to
		1508	implement this functionality, due to the requirement of having a file
		1509	descriptor open on the object at all times).
		1510
		1511	=head3 The special problem of stat time resolution
		1512
		1513	The C<stat ()> syscall only supports full-second resolution portably, and
		1514	even on systems where the resolution is higher, many filesystems still
		1515	only support whole seconds.
		1516
		1517	That means that, if the time is the only thing that changes, you might
		1518	miss updates: on the first update, C<ev_stat> detects a change and calls
		1519	your callback, which does something. When there is another update within
		1520	the same second, C<ev_stat> will be unable to detect it.
		1521
		1522	The solution to this is to delay acting on a change for a second (or till
		1523	the next second boundary), using a roughly one-second delay C<ev_timer>
		1524	(C<ev_timer_set (w, 0., 1.01); ev_timer_again (loop, w)>). The C<.01>
		1525	is added to work around small timing inconsistencies of some operating
		1526	systems.
		1527
		1528	=head3 Watcher-Specific Functions and Data Members
1165		1529
1166	=over 4	1530	=over 4
1167		1531
1168	=item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)	1532	=item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)
1169		1533
…		…
1205	=item const char *path [read-only]	1569	=item const char *path [read-only]
1206		1570
1207	The filesystem path that is being watched.	1571	The filesystem path that is being watched.
1208		1572
1209	=back	1573	=back
		1574
		1575	=head3 Examples
1210		1576
1211	Example: Watch C</etc/passwd> for attribute changes.	1577	Example: Watch C</etc/passwd> for attribute changes.
1212		1578
1213	static void	1579	static void
1214	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)	1580	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
…		…
1227	}	1593	}
1228		1594
1229	...	1595	...
1230	ev_stat passwd;	1596	ev_stat passwd;
1231		1597
1232	ev_stat_init (&passwd, passwd_cb, "/etc/passwd");	1598	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);
1233	ev_stat_start (loop, &passwd);	1599	ev_stat_start (loop, &passwd);
1234		1600
		1601	Example: Like above, but additionally use a one-second delay so we do not
		1602	miss updates (however, frequent updates will delay processing, too, so
		1603	one might do the work both on C<ev_stat> callback invocation I<and> on
		1604	C<ev_timer> callback invocation).
		1605
		1606	static ev_stat passwd;
		1607	static ev_timer timer;
		1608
		1609	static void
		1610	timer_cb (EV_P_ ev_timer *w, int revents)
		1611	{
		1612	ev_timer_stop (EV_A_ w);
		1613
		1614	/* now it's one second after the most recent passwd change */
		1615	}
		1616
		1617	static void
		1618	stat_cb (EV_P_ ev_stat *w, int revents)
		1619	{
		1620	/* reset the one-second timer */
		1621	ev_timer_again (EV_A_ &timer);
		1622	}
		1623
		1624	...
		1625	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);
		1626	ev_stat_start (loop, &passwd);
		1627	ev_timer_init (&timer, timer_cb, 0., 1.01);
		1628
1235		1629
1236	=head2 C<ev_idle> - when you've got nothing better to do...	1630	=head2 C<ev_idle> - when you've got nothing better to do...
1237		1631
1238	Idle watchers trigger events when there are no other events are pending	1632	Idle watchers trigger events when no other events of the same or higher
1239	(prepare, check and other idle watchers do not count). That is, as long	1633	priority are pending (prepare, check and other idle watchers do not
1240	as your process is busy handling sockets or timeouts (or even signals,	1634	count).
1241	imagine) it will not be triggered. But when your process is idle all idle	1635
1242	watchers are being called again and again, once per event loop iteration -	1636	That is, as long as your process is busy handling sockets or timeouts
		1637	(or even signals, imagine) of the same or higher priority it will not be
		1638	triggered. But when your process is idle (or only lower-priority watchers
		1639	are pending), the idle watchers are being called once per event loop
1243	until stopped, that is, or your process receives more events and becomes	1640	iteration - until stopped, that is, or your process receives more events
1244	busy.	1641	and becomes busy again with higher priority stuff.
1245		1642
1246	The most noteworthy effect is that as long as any idle watchers are	1643	The most noteworthy effect is that as long as any idle watchers are
1247	active, the process will not block when waiting for new events.	1644	active, the process will not block when waiting for new events.
1248		1645
1249	Apart from keeping your process non-blocking (which is a useful	1646	Apart from keeping your process non-blocking (which is a useful
1250	effect on its own sometimes), idle watchers are a good place to do	1647	effect on its own sometimes), idle watchers are a good place to do
1251	"pseudo-background processing", or delay processing stuff to after the	1648	"pseudo-background processing", or delay processing stuff to after the
1252	event loop has handled all outstanding events.	1649	event loop has handled all outstanding events.
1253		1650
		1651	=head3 Watcher-Specific Functions and Data Members
		1652
1254	=over 4	1653	=over 4
1255		1654
1256	=item ev_idle_init (ev_signal *, callback)	1655	=item ev_idle_init (ev_signal *, callback)
1257		1656
1258	Initialises and configures the idle watcher - it has no parameters of any	1657	Initialises and configures the idle watcher - it has no parameters of any
1259	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,	1658	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,
1260	believe me.	1659	believe me.
1261		1660
1262	=back	1661	=back
1263		1662
1264	Example: dynamically allocate an C<ev_idle>, start it, and in the	1663	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1265	callback, free it. Alos, use no error checking, as usual.	1664	callback, free it. Also, use no error checking, as usual.
1266		1665
1267	static void	1666	static void
1268	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)	1667	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1269	{	1668	{
1270	free (w);	1669	free (w);
…		…
1315	with priority higher than or equal to the event loop and one coroutine	1714	with priority higher than or equal to the event loop and one coroutine
1316	of lower priority, but only once, using idle watchers to keep the event	1715	of lower priority, but only once, using idle watchers to keep the event
1317	loop from blocking if lower-priority coroutines are active, thus mapping	1716	loop from blocking if lower-priority coroutines are active, thus mapping
1318	low-priority coroutines to idle/background tasks).	1717	low-priority coroutines to idle/background tasks).
1319		1718
		1719	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)
		1720	priority, to ensure that they are being run before any other watchers
		1721	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,
		1722	too) should not activate ("feed") events into libev. While libev fully
		1723	supports this, they will be called before other C<ev_check> watchers
		1724	did their job. As C<ev_check> watchers are often used to embed other
		1725	(non-libev) event loops those other event loops might be in an unusable
		1726	state until their C<ev_check> watcher ran (always remind yourself to
		1727	coexist peacefully with others).
		1728
		1729	=head3 Watcher-Specific Functions and Data Members
		1730
1320	=over 4	1731	=over 4
1321		1732
1322	=item ev_prepare_init (ev_prepare *, callback)	1733	=item ev_prepare_init (ev_prepare *, callback)
1323		1734
1324	=item ev_check_init (ev_check *, callback)	1735	=item ev_check_init (ev_check *, callback)
…		…
1327	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>	1738	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>
1328	macros, but using them is utterly, utterly and completely pointless.	1739	macros, but using them is utterly, utterly and completely pointless.
1329		1740
1330	=back	1741	=back
1331		1742
1332	Example: To include a library such as adns, you would add IO watchers	1743	There are a number of principal ways to embed other event loops or modules
1333	and a timeout watcher in a prepare handler, as required by libadns, and	1744	into libev. Here are some ideas on how to include libadns into libev
		1745	(there is a Perl module named C<EV::ADNS> that does this, which you could
		1746	use for an actually working example. Another Perl module named C<EV::Glib>
		1747	embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV
		1748	into the Glib event loop).
		1749
		1750	Method 1: Add IO watchers and a timeout watcher in a prepare handler,
1334	in a check watcher, destroy them and call into libadns. What follows is	1751	and in a check watcher, destroy them and call into libadns. What follows
1335	pseudo-code only of course:	1752	is pseudo-code only of course. This requires you to either use a low
		1753	priority for the check watcher or use C<ev_clear_pending> explicitly, as
		1754	the callbacks for the IO/timeout watchers might not have been called yet.
1336		1755
1337	static ev_io iow [nfd];	1756	static ev_io iow [nfd];
1338	static ev_timer tw;	1757	static ev_timer tw;
1339		1758
1340	static void	1759	static void
1341	io_cb (ev_loop *loop, ev_io *w, int revents)	1760	io_cb (ev_loop *loop, ev_io *w, int revents)
1342	{	1761	{
1343	// set the relevant poll flags
1344	// could also call adns_processreadable etc. here
1345	struct pollfd *fd = (struct pollfd *)w->data;
1346	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1347	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1348	}	1762	}
1349		1763
1350	// create io watchers for each fd and a timer before blocking	1764	// create io watchers for each fd and a timer before blocking
1351	static void	1765	static void
1352	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)	1766	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1353	{	1767	{
1354	int timeout = 3600000;truct pollfd fds [nfd];	1768	int timeout = 3600000;
		1769	struct pollfd fds [nfd];
1355	// actual code will need to loop here and realloc etc.	1770	// actual code will need to loop here and realloc etc.
1356	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1771	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1357		1772
1358	/* the callback is illegal, but won't be called as we stop during check */	1773	/* the callback is illegal, but won't be called as we stop during check */
1359	ev_timer_init (&tw, 0, timeout * 1e-3);	1774	ev_timer_init (&tw, 0, timeout * 1e-3);
1360	ev_timer_start (loop, &tw);	1775	ev_timer_start (loop, &tw);
1361		1776
1362	// create on ev_io per pollfd	1777	// create one ev_io per pollfd
1363	for (int i = 0; i < nfd; ++i)	1778	for (int i = 0; i < nfd; ++i)
1364	{	1779	{
1365	ev_io_init (iow + i, io_cb, fds [i].fd,	1780	ev_io_init (iow + i, io_cb, fds [i].fd,
1366	((fds [i].events & POLLIN ? EV_READ : 0)	1781	((fds [i].events & POLLIN ? EV_READ : 0)
1367	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	1782	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1368		1783
1369	fds [i].revents = 0;	1784	fds [i].revents = 0;
1370	iow [i].data = fds + i;
1371	ev_io_start (loop, iow + i);	1785	ev_io_start (loop, iow + i);
1372	}	1786	}
1373	}	1787	}
1374		1788
1375	// stop all watchers after blocking	1789	// stop all watchers after blocking
…		…
1377	adns_check_cb (ev_loop *loop, ev_check *w, int revents)	1791	adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1378	{	1792	{
1379	ev_timer_stop (loop, &tw);	1793	ev_timer_stop (loop, &tw);
1380		1794
1381	for (int i = 0; i < nfd; ++i)	1795	for (int i = 0; i < nfd; ++i)
		1796	{
		1797	// set the relevant poll flags
		1798	// could also call adns_processreadable etc. here
		1799	struct pollfd *fd = fds + i;
		1800	int revents = ev_clear_pending (iow + i);
		1801	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
		1802	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
		1803
		1804	// now stop the watcher
1382	ev_io_stop (loop, iow + i);	1805	ev_io_stop (loop, iow + i);
		1806	}
1383		1807
1384	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	1808	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1809	}
		1810
		1811	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
		1812	in the prepare watcher and would dispose of the check watcher.
		1813
		1814	Method 3: If the module to be embedded supports explicit event
		1815	notification (adns does), you can also make use of the actual watcher
		1816	callbacks, and only destroy/create the watchers in the prepare watcher.
		1817
		1818	static void
		1819	timer_cb (EV_P_ ev_timer *w, int revents)
		1820	{
		1821	adns_state ads = (adns_state)w->data;
		1822	update_now (EV_A);
		1823
		1824	adns_processtimeouts (ads, &tv_now);
		1825	}
		1826
		1827	static void
		1828	io_cb (EV_P_ ev_io *w, int revents)
		1829	{
		1830	adns_state ads = (adns_state)w->data;
		1831	update_now (EV_A);
		1832
		1833	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
		1834	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
		1835	}
		1836
		1837	// do not ever call adns_afterpoll
		1838
		1839	Method 4: Do not use a prepare or check watcher because the module you
		1840	want to embed is too inflexible to support it. Instead, youc na override
		1841	their poll function. The drawback with this solution is that the main
		1842	loop is now no longer controllable by EV. The C<Glib::EV> module does
		1843	this.
		1844
		1845	static gint
		1846	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
		1847	{
		1848	int got_events = 0;
		1849
		1850	for (n = 0; n < nfds; ++n)
		1851	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
		1852
		1853	if (timeout >= 0)
		1854	// create/start timer
		1855
		1856	// poll
		1857	ev_loop (EV_A_ 0);
		1858
		1859	// stop timer again
		1860	if (timeout >= 0)
		1861	ev_timer_stop (EV_A_ &to);
		1862
		1863	// stop io watchers again - their callbacks should have set
		1864	for (n = 0; n < nfds; ++n)
		1865	ev_io_stop (EV_A_ iow [n]);
		1866
		1867	return got_events;
1385	}	1868	}
1386		1869
1387		1870
1388	=head2 C<ev_embed> - when one backend isn't enough...	1871	=head2 C<ev_embed> - when one backend isn't enough...
1389		1872
…		…
1453	ev_embed_start (loop_hi, &embed);	1936	ev_embed_start (loop_hi, &embed);
1454	}	1937	}
1455	else	1938	else
1456	loop_lo = loop_hi;	1939	loop_lo = loop_hi;
1457		1940
		1941	=head3 Watcher-Specific Functions and Data Members
		1942
1458	=over 4	1943	=over 4
1459		1944
1460	=item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)	1945	=item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)
1461		1946
1462	=item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)	1947	=item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)
…		…
1471		1956
1472	Make a single, non-blocking sweep over the embedded loop. This works	1957	Make a single, non-blocking sweep over the embedded loop. This works
1473	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	1958	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
1474	apropriate way for embedded loops.	1959	apropriate way for embedded loops.
1475		1960
1476	=item struct ev_loop *loop [read-only]	1961	=item struct ev_loop *other [read-only]
1477		1962
1478	The embedded event loop.	1963	The embedded event loop.
1479		1964
1480	=back	1965	=back
1481		1966
…		…
1488	event loop blocks next and before C<ev_check> watchers are being called,	1973	event loop blocks next and before C<ev_check> watchers are being called,
1489	and only in the child after the fork. If whoever good citizen calling	1974	and only in the child after the fork. If whoever good citizen calling
1490	C<ev_default_fork> cheats and calls it in the wrong process, the fork	1975	C<ev_default_fork> cheats and calls it in the wrong process, the fork
1491	handlers will be invoked, too, of course.	1976	handlers will be invoked, too, of course.
1492		1977
		1978	=head3 Watcher-Specific Functions and Data Members
		1979
1493	=over 4	1980	=over 4
1494		1981
1495	=item ev_fork_init (ev_signal *, callback)	1982	=item ev_fork_init (ev_signal *, callback)
1496		1983
1497	Initialises and configures the fork watcher - it has no parameters of any	1984	Initialises and configures the fork watcher - it has no parameters of any
…		…
1593		2080
1594	To use it,	2081	To use it,
1595		2082
1596	#include <ev++.h>	2083	#include <ev++.h>
1597		2084
1598	(it is not installed by default). This automatically includes F<ev.h>	2085	This automatically includes F<ev.h> and puts all of its definitions (many
1599	and puts all of its definitions (many of them macros) into the global	2086	of them macros) into the global namespace. All C++ specific things are
1600	namespace. All C++ specific things are put into the C<ev> namespace.	2087	put into the C<ev> namespace. It should support all the same embedding
		2088	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
1601		2089
1602	It should support all the same embedding options as F<ev.h>, most notably	2090	Care has been taken to keep the overhead low. The only data member the C++
1603	C<EV_MULTIPLICITY>.	2091	classes add (compared to plain C-style watchers) is the event loop pointer
		2092	that the watcher is associated with (or no additional members at all if
		2093	you disable C<EV_MULTIPLICITY> when embedding libev).
		2094
		2095	Currently, functions, and static and non-static member functions can be
		2096	used as callbacks. Other types should be easy to add as long as they only
		2097	need one additional pointer for context. If you need support for other
		2098	types of functors please contact the author (preferably after implementing
		2099	it).
1604		2100
1605	Here is a list of things available in the C<ev> namespace:	2101	Here is a list of things available in the C<ev> namespace:
1606		2102
1607	=over 4	2103	=over 4
1608		2104
…		…
1624		2120
1625	All of those classes have these methods:	2121	All of those classes have these methods:
1626		2122
1627	=over 4	2123	=over 4
1628		2124
1629	=item ev::TYPE::TYPE (object *, object::method *)	2125	=item ev::TYPE::TYPE ()
1630		2126
1631	=item ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)	2127	=item ev::TYPE::TYPE (struct ev_loop *)
1632		2128
1633	=item ev::TYPE::~TYPE	2129	=item ev::TYPE::~TYPE
1634		2130
1635	The constructor takes a pointer to an object and a method pointer to	2131	The constructor (optionally) takes an event loop to associate the watcher
1636	the event handler callback to call in this class. The constructor calls	2132	with. If it is omitted, it will use C<EV_DEFAULT>.
1637	C<ev_init> for you, which means you have to call the C<set> method	2133
1638	before starting it. If you do not specify a loop then the constructor	2134	The constructor calls C<ev_init> for you, which means you have to call the
1639	automatically associates the default loop with this watcher.	2135	C<set> method before starting it.
		2136
		2137	It will not set a callback, however: You have to call the templated C<set>
		2138	method to set a callback before you can start the watcher.
		2139
		2140	(The reason why you have to use a method is a limitation in C++ which does
		2141	not allow explicit template arguments for constructors).
1640		2142
1641	The destructor automatically stops the watcher if it is active.	2143	The destructor automatically stops the watcher if it is active.
		2144
		2145	=item w->set<class, &class::method> (object *)
		2146
		2147	This method sets the callback method to call. The method has to have a
		2148	signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as
		2149	first argument and the C<revents> as second. The object must be given as
		2150	parameter and is stored in the C<data> member of the watcher.
		2151
		2152	This method synthesizes efficient thunking code to call your method from
		2153	the C callback that libev requires. If your compiler can inline your
		2154	callback (i.e. it is visible to it at the place of the C<set> call and
		2155	your compiler is good :), then the method will be fully inlined into the
		2156	thunking function, making it as fast as a direct C callback.
		2157
		2158	Example: simple class declaration and watcher initialisation
		2159
		2160	struct myclass
		2161	{
		2162	void io_cb (ev::io &w, int revents) { }
		2163	}
		2164
		2165	myclass obj;
		2166	ev::io iow;
		2167	iow.set <myclass, &myclass::io_cb> (&obj);
		2168
		2169	=item w->set<function> (void *data = 0)
		2170
		2171	Also sets a callback, but uses a static method or plain function as
		2172	callback. The optional C<data> argument will be stored in the watcher's
		2173	C<data> member and is free for you to use.
		2174
		2175	The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>.
		2176
		2177	See the method-C<set> above for more details.
		2178
		2179	Example:
		2180
		2181	static void io_cb (ev::io &w, int revents) { }
		2182	iow.set <io_cb> ();
1642		2183
1643	=item w->set (struct ev_loop *)	2184	=item w->set (struct ev_loop *)
1644		2185
1645	Associates a different C<struct ev_loop> with this watcher. You can only	2186	Associates a different C<struct ev_loop> with this watcher. You can only
1646	do this when the watcher is inactive (and not pending either).	2187	do this when the watcher is inactive (and not pending either).
1647		2188
1648	=item w->set ([args])	2189	=item w->set ([args])
1649		2190
1650	Basically the same as C<ev_TYPE_set>, with the same args. Must be	2191	Basically the same as C<ev_TYPE_set>, with the same args. Must be
1651	called at least once. Unlike the C counterpart, an active watcher gets	2192	called at least once. Unlike the C counterpart, an active watcher gets
1652	automatically stopped and restarted.	2193	automatically stopped and restarted when reconfiguring it with this
		2194	method.
1653		2195
1654	=item w->start ()	2196	=item w->start ()
1655		2197
1656	Starts the watcher. Note that there is no C<loop> argument as the	2198	Starts the watcher. Note that there is no C<loop> argument, as the
1657	constructor already takes the loop.	2199	constructor already stores the event loop.
1658		2200
1659	=item w->stop ()	2201	=item w->stop ()
1660		2202
1661	Stops the watcher if it is active. Again, no C<loop> argument.	2203	Stops the watcher if it is active. Again, no C<loop> argument.
1662		2204
1663	=item w->again () C<ev::timer>, C<ev::periodic> only	2205	=item w->again () (C<ev::timer>, C<ev::periodic> only)
1664		2206
1665	For C<ev::timer> and C<ev::periodic>, this invokes the corresponding	2207	For C<ev::timer> and C<ev::periodic>, this invokes the corresponding
1666	C<ev_TYPE_again> function.	2208	C<ev_TYPE_again> function.
1667		2209
1668	=item w->sweep () C<ev::embed> only	2210	=item w->sweep () (C<ev::embed> only)
1669		2211
1670	Invokes C<ev_embed_sweep>.	2212	Invokes C<ev_embed_sweep>.
1671		2213
1672	=item w->update () C<ev::stat> only	2214	=item w->update () (C<ev::stat> only)
1673		2215
1674	Invokes C<ev_stat_stat>.	2216	Invokes C<ev_stat_stat>.
1675		2217
1676	=back	2218	=back
1677		2219
…		…
1687		2229
1688	myclass ();	2230	myclass ();
1689	}	2231	}
1690		2232
1691	myclass::myclass (int fd)	2233	myclass::myclass (int fd)
1692	: io (this, &myclass::io_cb),
1693	idle (this, &myclass::idle_cb)
1694	{	2234	{
		2235	io .set <myclass, &myclass::io_cb > (this);
		2236	idle.set <myclass, &myclass::idle_cb> (this);
		2237
1695	io.start (fd, ev::READ);	2238	io.start (fd, ev::READ);
1696	}	2239	}
1697		2240
1698		2241
1699	=head1 MACRO MAGIC	2242	=head1 MACRO MAGIC
1700		2243
1701	Libev can be compiled with a variety of options, the most fundemantal is	2244	Libev can be compiled with a variety of options, the most fundamantal
1702	C<EV_MULTIPLICITY>. This option determines wether (most) functions and	2245	of which is C<EV_MULTIPLICITY>. This option determines whether (most)
1703	callbacks have an initial C<struct ev_loop *> argument.	2246	functions and callbacks have an initial C<struct ev_loop *> argument.
1704		2247
1705	To make it easier to write programs that cope with either variant, the	2248	To make it easier to write programs that cope with either variant, the
1706	following macros are defined:	2249	following macros are defined:
1707		2250
1708	=over 4	2251	=over 4
…		…
1740	Similar to the other two macros, this gives you the value of the default	2283	Similar to the other two macros, this gives you the value of the default
1741	loop, if multiple loops are supported ("ev loop default").	2284	loop, if multiple loops are supported ("ev loop default").
1742		2285
1743	=back	2286	=back
1744		2287
1745	Example: Declare and initialise a check watcher, working regardless of	2288	Example: Declare and initialise a check watcher, utilising the above
1746	wether multiple loops are supported or not.	2289	macros so it will work regardless of whether multiple loops are supported
		2290	or not.
1747		2291
1748	static void	2292	static void
1749	check_cb (EV_P_ ev_timer *w, int revents)	2293	check_cb (EV_P_ ev_timer *w, int revents)
1750	{	2294	{
1751	ev_check_stop (EV_A_ w);	2295	ev_check_stop (EV_A_ w);
…		…
1754	ev_check check;	2298	ev_check check;
1755	ev_check_init (&check, check_cb);	2299	ev_check_init (&check, check_cb);
1756	ev_check_start (EV_DEFAULT_ &check);	2300	ev_check_start (EV_DEFAULT_ &check);
1757	ev_loop (EV_DEFAULT_ 0);	2301	ev_loop (EV_DEFAULT_ 0);
1758		2302
1759
1760	=head1 EMBEDDING	2303	=head1 EMBEDDING
1761		2304
1762	Libev can (and often is) directly embedded into host	2305	Libev can (and often is) directly embedded into host
1763	applications. Examples of applications that embed it include the Deliantra	2306	applications. Examples of applications that embed it include the Deliantra
1764	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)	2307	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
1765	and rxvt-unicode.	2308	and rxvt-unicode.
1766		2309
1767	The goal is to enable you to just copy the neecssary files into your	2310	The goal is to enable you to just copy the necessary files into your
1768	source directory without having to change even a single line in them, so	2311	source directory without having to change even a single line in them, so
1769	you can easily upgrade by simply copying (or having a checked-out copy of	2312	you can easily upgrade by simply copying (or having a checked-out copy of
1770	libev somewhere in your source tree).	2313	libev somewhere in your source tree).
1771		2314
1772	=head2 FILESETS	2315	=head2 FILESETS
…		…
1803	ev_vars.h	2346	ev_vars.h
1804	ev_wrap.h	2347	ev_wrap.h
1805		2348
1806	ev_win32.c required on win32 platforms only	2349	ev_win32.c required on win32 platforms only
1807		2350
1808	ev_select.c only when select backend is enabled (which is by default)	2351	ev_select.c only when select backend is enabled (which is enabled by default)
1809	ev_poll.c only when poll backend is enabled (disabled by default)	2352	ev_poll.c only when poll backend is enabled (disabled by default)
1810	ev_epoll.c only when the epoll backend is enabled (disabled by default)	2353	ev_epoll.c only when the epoll backend is enabled (disabled by default)
1811	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	2354	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
1812	ev_port.c only when the solaris port backend is enabled (disabled by default)	2355	ev_port.c only when the solaris port backend is enabled (disabled by default)
1813		2356
…		…
1862		2405
1863	If defined to be C<1>, libev will try to detect the availability of the	2406	If defined to be C<1>, libev will try to detect the availability of the
1864	monotonic clock option at both compiletime and runtime. Otherwise no use	2407	monotonic clock option at both compiletime and runtime. Otherwise no use
1865	of the monotonic clock option will be attempted. If you enable this, you	2408	of the monotonic clock option will be attempted. If you enable this, you
1866	usually have to link against librt or something similar. Enabling it when	2409	usually have to link against librt or something similar. Enabling it when
1867	the functionality isn't available is safe, though, althoguh you have	2410	the functionality isn't available is safe, though, although you have
1868	to make sure you link against any libraries where the C<clock_gettime>	2411	to make sure you link against any libraries where the C<clock_gettime>
1869	function is hiding in (often F<-lrt>).	2412	function is hiding in (often F<-lrt>).
1870		2413
1871	=item EV_USE_REALTIME	2414	=item EV_USE_REALTIME
1872		2415
1873	If defined to be C<1>, libev will try to detect the availability of the	2416	If defined to be C<1>, libev will try to detect the availability of the
1874	realtime clock option at compiletime (and assume its availability at	2417	realtime clock option at compiletime (and assume its availability at
1875	runtime if successful). Otherwise no use of the realtime clock option will	2418	runtime if successful). Otherwise no use of the realtime clock option will
1876	be attempted. This effectively replaces C<gettimeofday> by C<clock_get	2419	be attempted. This effectively replaces C<gettimeofday> by C<clock_get
1877	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries	2420	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the
1878	in the description of C<EV_USE_MONOTONIC>, though.	2421	note about libraries in the description of C<EV_USE_MONOTONIC>, though.
		2422
		2423	=item EV_USE_NANOSLEEP
		2424
		2425	If defined to be C<1>, libev will assume that C<nanosleep ()> is available
		2426	and will use it for delays. Otherwise it will use C<select ()>.
1879		2427
1880	=item EV_USE_SELECT	2428	=item EV_USE_SELECT
1881		2429
1882	If undefined or defined to be C<1>, libev will compile in support for the	2430	If undefined or defined to be C<1>, libev will compile in support for the
1883	C<select>(2) backend. No attempt at autodetection will be done: if no	2431	C<select>(2) backend. No attempt at autodetection will be done: if no
…		…
1938		2486
1939	=item EV_USE_DEVPOLL	2487	=item EV_USE_DEVPOLL
1940		2488
1941	reserved for future expansion, works like the USE symbols above.	2489	reserved for future expansion, works like the USE symbols above.
1942		2490
		2491	=item EV_USE_INOTIFY
		2492
		2493	If defined to be C<1>, libev will compile in support for the Linux inotify
		2494	interface to speed up C<ev_stat> watchers. Its actual availability will
		2495	be detected at runtime.
		2496
1943	=item EV_H	2497	=item EV_H
1944		2498
1945	The name of the F<ev.h> header file used to include it. The default if	2499	The name of the F<ev.h> header file used to include it. The default if
1946	undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This	2500	undefined is C<"ev.h"> in F<event.h> and F<ev.c>. This can be used to
1947	can be used to virtually rename the F<ev.h> header file in case of conflicts.	2501	virtually rename the F<ev.h> header file in case of conflicts.
1948		2502
1949	=item EV_CONFIG_H	2503	=item EV_CONFIG_H
1950		2504
1951	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override	2505	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override
1952	F<ev.c>'s idea of where to find the F<config.h> file, similarly to	2506	F<ev.c>'s idea of where to find the F<config.h> file, similarly to
1953	C<EV_H>, above.	2507	C<EV_H>, above.
1954		2508
1955	=item EV_EVENT_H	2509	=item EV_EVENT_H
1956		2510
1957	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea	2511	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea
1958	of how the F<event.h> header can be found.	2512	of how the F<event.h> header can be found, the dfeault is C<"event.h">.
1959		2513
1960	=item EV_PROTOTYPES	2514	=item EV_PROTOTYPES
1961		2515
1962	If defined to be C<0>, then F<ev.h> will not define any function	2516	If defined to be C<0>, then F<ev.h> will not define any function
1963	prototypes, but still define all the structs and other symbols. This is	2517	prototypes, but still define all the structs and other symbols. This is
…		…
1970	will have the C<struct ev_loop *> as first argument, and you can create	2524	will have the C<struct ev_loop *> as first argument, and you can create
1971	additional independent event loops. Otherwise there will be no support	2525	additional independent event loops. Otherwise there will be no support
1972	for multiple event loops and there is no first event loop pointer	2526	for multiple event loops and there is no first event loop pointer
1973	argument. Instead, all functions act on the single default loop.	2527	argument. Instead, all functions act on the single default loop.
1974		2528
		2529	=item EV_MINPRI
		2530
		2531	=item EV_MAXPRI
		2532
		2533	The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to
		2534	C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can
		2535	provide for more priorities by overriding those symbols (usually defined
		2536	to be C<-2> and C<2>, respectively).
		2537
		2538	When doing priority-based operations, libev usually has to linearly search
		2539	all the priorities, so having many of them (hundreds) uses a lot of space
		2540	and time, so using the defaults of five priorities (-2 .. +2) is usually
		2541	fine.
		2542
		2543	If your embedding app does not need any priorities, defining these both to
		2544	C<0> will save some memory and cpu.
		2545
1975	=item EV_PERIODIC_ENABLE	2546	=item EV_PERIODIC_ENABLE
1976		2547
1977	If undefined or defined to be C<1>, then periodic timers are supported. If	2548	If undefined or defined to be C<1>, then periodic timers are supported. If
1978	defined to be C<0>, then they are not. Disabling them saves a few kB of	2549	defined to be C<0>, then they are not. Disabling them saves a few kB of
1979	code.	2550	code.
1980		2551
		2552	=item EV_IDLE_ENABLE
		2553
		2554	If undefined or defined to be C<1>, then idle watchers are supported. If
		2555	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2556	code.
		2557
1981	=item EV_EMBED_ENABLE	2558	=item EV_EMBED_ENABLE
1982		2559
1983	If undefined or defined to be C<1>, then embed watchers are supported. If	2560	If undefined or defined to be C<1>, then embed watchers are supported. If
1984	defined to be C<0>, then they are not.	2561	defined to be C<0>, then they are not.
1985		2562
…		…
1996	=item EV_MINIMAL	2573	=item EV_MINIMAL
1997		2574
1998	If you need to shave off some kilobytes of code at the expense of some	2575	If you need to shave off some kilobytes of code at the expense of some
1999	speed, define this symbol to C<1>. Currently only used for gcc to override	2576	speed, define this symbol to C<1>. Currently only used for gcc to override
2000	some inlining decisions, saves roughly 30% codesize of amd64.	2577	some inlining decisions, saves roughly 30% codesize of amd64.
		2578
		2579	=item EV_PID_HASHSIZE
		2580
		2581	C<ev_child> watchers use a small hash table to distribute workload by
		2582	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
		2583	than enough. If you need to manage thousands of children you might want to
		2584	increase this value (I<must> be a power of two).
		2585
		2586	=item EV_INOTIFY_HASHSIZE
		2587
		2588	C<ev_stat> watchers use a small hash table to distribute workload by
		2589	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
		2590	usually more than enough. If you need to manage thousands of C<ev_stat>
		2591	watchers you might want to increase this value (I<must> be a power of
		2592	two).
2001		2593
2002	=item EV_COMMON	2594	=item EV_COMMON
2003		2595
2004	By default, all watchers have a C<void *data> member. By redefining	2596	By default, all watchers have a C<void *data> member. By redefining
2005	this macro to a something else you can include more and other types of	2597	this macro to a something else you can include more and other types of
…		…
2018		2610
2019	=item ev_set_cb (ev, cb)	2611	=item ev_set_cb (ev, cb)
2020		2612
2021	Can be used to change the callback member declaration in each watcher,	2613	Can be used to change the callback member declaration in each watcher,
2022	and the way callbacks are invoked and set. Must expand to a struct member	2614	and the way callbacks are invoked and set. Must expand to a struct member
2023	definition and a statement, respectively. See the F<ev.v> header file for	2615	definition and a statement, respectively. See the F<ev.h> header file for
2024	their default definitions. One possible use for overriding these is to	2616	their default definitions. One possible use for overriding these is to
2025	avoid the C<struct ev_loop *> as first argument in all cases, or to use	2617	avoid the C<struct ev_loop *> as first argument in all cases, or to use
2026	method calls instead of plain function calls in C++.	2618	method calls instead of plain function calls in C++.
		2619
		2620	=head2 EXPORTED API SYMBOLS
		2621
		2622	If you need to re-export the API (e.g. via a dll) and you need a list of
		2623	exported symbols, you can use the provided F<Symbol.*> files which list
		2624	all public symbols, one per line:
		2625
		2626	Symbols.ev for libev proper
		2627	Symbols.event for the libevent emulation
		2628
		2629	This can also be used to rename all public symbols to avoid clashes with
		2630	multiple versions of libev linked together (which is obviously bad in
		2631	itself, but sometimes it is inconvinient to avoid this).
		2632
		2633	A sed command like this will create wrapper C<#define>'s that you need to
		2634	include before including F<ev.h>:
		2635
		2636	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h
		2637
		2638	This would create a file F<wrap.h> which essentially looks like this:
		2639
		2640	#define ev_backend myprefix_ev_backend
		2641	#define ev_check_start myprefix_ev_check_start
		2642	#define ev_check_stop myprefix_ev_check_stop
		2643	...
2027		2644
2028	=head2 EXAMPLES	2645	=head2 EXAMPLES
2029		2646
2030	For a real-world example of a program the includes libev	2647	For a real-world example of a program the includes libev
2031	verbatim, you can have a look at the EV perl module	2648	verbatim, you can have a look at the EV perl module
…		…
2034	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file	2651	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file
2035	will be compiled. It is pretty complex because it provides its own header	2652	will be compiled. It is pretty complex because it provides its own header
2036	file.	2653	file.
2037		2654
2038	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	2655	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
2039	that everybody includes and which overrides some autoconf choices:	2656	that everybody includes and which overrides some configure choices:
2040		2657
		2658	#define EV_MINIMAL 1
2041	#define EV_USE_POLL 0	2659	#define EV_USE_POLL 0
2042	#define EV_MULTIPLICITY 0	2660	#define EV_MULTIPLICITY 0
2043	#define EV_PERIODICS 0	2661	#define EV_PERIODIC_ENABLE 0
		2662	#define EV_STAT_ENABLE 0
		2663	#define EV_FORK_ENABLE 0
2044	#define EV_CONFIG_H <config.h>	2664	#define EV_CONFIG_H <config.h>
		2665	#define EV_MINPRI 0
		2666	#define EV_MAXPRI 0
2045		2667
2046	#include "ev++.h"	2668	#include "ev++.h"
2047		2669
2048	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	2670	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
2049		2671
…		…
2055		2677
2056	In this section the complexities of (many of) the algorithms used inside	2678	In this section the complexities of (many of) the algorithms used inside
2057	libev will be explained. For complexity discussions about backends see the	2679	libev will be explained. For complexity discussions about backends see the
2058	documentation for C<ev_default_init>.	2680	documentation for C<ev_default_init>.
2059		2681
		2682	All of the following are about amortised time: If an array needs to be
		2683	extended, libev needs to realloc and move the whole array, but this
		2684	happens asymptotically never with higher number of elements, so O(1) might
		2685	mean it might do a lengthy realloc operation in rare cases, but on average
		2686	it is much faster and asymptotically approaches constant time.
		2687
2060	=over 4	2688	=over 4
2061		2689
2062	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)	2690	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
2063		2691
		2692	This means that, when you have a watcher that triggers in one hour and
		2693	there are 100 watchers that would trigger before that then inserting will
		2694	have to skip roughly seven (C<ld 100>) of these watchers.
		2695
2064	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)	2696	=item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers)
		2697
		2698	That means that changing a timer costs less than removing/adding them
		2699	as only the relative motion in the event queue has to be paid for.
2065		2700
2066	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2701	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
2067		2702
		2703	These just add the watcher into an array or at the head of a list.
		2704
2068	=item Stopping check/prepare/idle watchers: O(1)	2705	=item Stopping check/prepare/idle watchers: O(1)
2069		2706
2070	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))	2707	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
2071		2708
		2709	These watchers are stored in lists then need to be walked to find the
		2710	correct watcher to remove. The lists are usually short (you don't usually
		2711	have many watchers waiting for the same fd or signal).
		2712
2072	=item Finding the next timer per loop iteration: O(1)	2713	=item Finding the next timer in each loop iteration: O(1)
		2714
		2715	By virtue of using a binary heap, the next timer is always found at the
		2716	beginning of the storage array.
2073		2717
2074	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	2718	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
2075		2719
2076	=item Activating one watcher: O(1)	2720	A change means an I/O watcher gets started or stopped, which requires
		2721	libev to recalculate its status (and possibly tell the kernel, depending
		2722	on backend and wether C<ev_io_set> was used).
		2723
		2724	=item Activating one watcher (putting it into the pending state): O(1)
		2725
		2726	=item Priority handling: O(number_of_priorities)
		2727
		2728	Priorities are implemented by allocating some space for each
		2729	priority. When doing priority-based operations, libev usually has to
		2730	linearly search all the priorities, but starting/stopping and activating
		2731	watchers becomes O(1) w.r.t. prioritiy handling.
2077		2732
2078	=back	2733	=back
2079		2734
2080		2735
2081	=head1 AUTHOR	2736	=head1 AUTHOR

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