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…		…
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	#include <ev.h>	7	#include <ev.h>
8		8
		9	=head2 EXAMPLE PROGRAM
		10
		11	#include <ev.h>
		12
		13	ev_io stdin_watcher;
		14	ev_timer timeout_watcher;
		15
		16	/* called when data readable on stdin */
		17	static void
		18	stdin_cb (EV_P_ struct ev_io *w, int revents)
		19	{
		20	/* puts ("stdin ready"); */
		21	ev_io_stop (EV_A_ w); /* just a syntax example */
		22	ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */
		23	}
		24
		25	static void
		26	timeout_cb (EV_P_ struct ev_timer *w, int revents)
		27	{
		28	/* puts ("timeout"); */
		29	ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */
		30	}
		31
		32	int
		33	main (void)
		34	{
		35	struct ev_loop *loop = ev_default_loop (0);
		36
		37	/* initialise an io watcher, then start it */
		38	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);
		39	ev_io_start (loop, &stdin_watcher);
		40
		41	/* simple non-repeating 5.5 second timeout */
		42	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
		43	ev_timer_start (loop, &timeout_watcher);
		44
		45	/* loop till timeout or data ready */
		46	ev_loop (loop, 0);
		47
		48	return 0;
		49	}
		50
9	=head1 DESCRIPTION	51	=head1 DESCRIPTION
10		52
		53	The newest version of this document is also available as a html-formatted
		54	web page you might find easier to navigate when reading it for the first
		55	time: L<http://cvs.schmorp.de/libev/ev.html>.
		56
11	Libev is an event loop: you register interest in certain events (such as a	57	Libev is an event loop: you register interest in certain events (such as a
12	file descriptor being readable or a timeout occuring), and it will manage	58	file descriptor being readable or a timeout occurring), and it will manage
13	these event sources and provide your program with events.	59	these event sources and provide your program with events.
14		60
15	To do this, it must take more or less complete control over your process	61	To do this, it must take more or less complete control over your process
16	(or thread) by executing the I<event loop> handler, and will then	62	(or thread) by executing the I<event loop> handler, and will then
17	communicate events via a callback mechanism.	63	communicate events via a callback mechanism.
…		…
19	You register interest in certain events by registering so-called I<event	65	You register interest in certain events by registering so-called I<event
20	watchers>, which are relatively small C structures you initialise with the	66	watchers>, which are relatively small C structures you initialise with the
21	details of the event, and then hand it over to libev by I<starting> the	67	details of the event, and then hand it over to libev by I<starting> the
22	watcher.	68	watcher.
23		69
24	=head1 FEATURES	70	=head2 FEATURES
25		71
26	Libev supports select, poll, the linux-specific epoll and the bsd-specific	72	Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the
27	kqueue mechanisms for file descriptor events, relative timers, absolute	73	BSD-specific C<kqueue> and the Solaris-specific event port mechanisms
28	timers with customised rescheduling, signal events, process status change	74	for file descriptor events (C<ev_io>), the Linux C<inotify> interface
29	events (related to SIGCHLD), and event watchers dealing with the event	75	(for C<ev_stat>), relative timers (C<ev_timer>), absolute timers
30	loop mechanism itself (idle, prepare and check watchers). It also is quite	76	with customised rescheduling (C<ev_periodic>), synchronous signals
		77	(C<ev_signal>), process status change events (C<ev_child>), and event
		78	watchers dealing with the event loop mechanism itself (C<ev_idle>,
		79	C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as
		80	file watchers (C<ev_stat>) and even limited support for fork events
		81	(C<ev_fork>).
		82
		83	It also is quite fast (see this
31	fast (see this L<benchmark|http://libev.schmorp.de/bench.html> comparing	84	L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent
32	it to libevent for example).	85	for example).
33		86
34	=head1 CONVENTIONS	87	=head2 CONVENTIONS
35		88
36	Libev is very configurable. In this manual the default configuration	89	Libev is very configurable. In this manual the default configuration will
37	will be described, which supports multiple event loops. For more info	90	be described, which supports multiple event loops. For more info about
38	about various configuration options please have a look at the file	91	various configuration options please have a look at B<EMBED> section in
39	F<README.embed> in the libev distribution. If libev was configured without	92	this manual. If libev was configured without support for multiple event
40	support for multiple event loops, then all functions taking an initial	93	loops, then all functions taking an initial argument of name C<loop>
41	argument of name C<loop> (which is always of type C<struct ev_loop *>)	94	(which is always of type C<struct ev_loop *>) will not have this argument.
42	will not have this argument.
43		95
44	=head1 TIME REPRESENTATION	96	=head2 TIME REPRESENTATION
45		97
46	Libev represents time as a single floating point number, representing the	98	Libev represents time as a single floating point number, representing the
47	(fractional) number of seconds since the (POSIX) epoch (somewhere near	99	(fractional) number of seconds since the (POSIX) epoch (somewhere near
48	the beginning of 1970, details are complicated, don't ask). This type is	100	the beginning of 1970, details are complicated, don't ask). This type is
49	called C<ev_tstamp>, which is what you should use too. It usually aliases	101	called C<ev_tstamp>, which is what you should use too. It usually aliases
50	to the C<double> type in C, and when you need to do any calculations on	102	to the C<double> type in C, and when you need to do any calculations on
51	it, you should treat it as such.	103	it, you should treat it as some floatingpoint value. Unlike the name
52		104	component C<stamp> might indicate, it is also used for time differences
		105	throughout libev.
53		106
54	=head1 GLOBAL FUNCTIONS	107	=head1 GLOBAL FUNCTIONS
55		108
56	These functions can be called anytime, even before initialising the	109	These functions can be called anytime, even before initialising the
57	library in any way.	110	library in any way.
…		…
62		115
63	Returns the current time as libev would use it. Please note that the	116	Returns the current time as libev would use it. Please note that the
64	C<ev_now> function is usually faster and also often returns the timestamp	117	C<ev_now> function is usually faster and also often returns the timestamp
65	you actually want to know.	118	you actually want to know.
66		119
		120	=item ev_sleep (ev_tstamp interval)
		121
		122	Sleep for the given interval: The current thread will be blocked until
		123	either it is interrupted or the given time interval has passed. Basically
		124	this is a subsecond-resolution C<sleep ()>.
		125
67	=item int ev_version_major ()	126	=item int ev_version_major ()
68		127
69	=item int ev_version_minor ()	128	=item int ev_version_minor ()
70		129
71	You can find out the major and minor version numbers of the library	130	You can find out the major and minor ABI version numbers of the library
72	you linked against by calling the functions C<ev_version_major> and	131	you linked against by calling the functions C<ev_version_major> and
73	C<ev_version_minor>. If you want, you can compare against the global	132	C<ev_version_minor>. If you want, you can compare against the global
74	symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the	133	symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the
75	version of the library your program was compiled against.	134	version of the library your program was compiled against.
76		135
		136	These version numbers refer to the ABI version of the library, not the
		137	release version.
		138
77	Usually, it's a good idea to terminate if the major versions mismatch,	139	Usually, it's a good idea to terminate if the major versions mismatch,
78	as this indicates an incompatible change. Minor versions are usually	140	as this indicates an incompatible change. Minor versions are usually
79	compatible to older versions, so a larger minor version alone is usually	141	compatible to older versions, so a larger minor version alone is usually
80	not a problem.	142	not a problem.
81		143
82	Example: make sure we haven't accidentally been linked against the wrong	144	Example: Make sure we haven't accidentally been linked against the wrong
83	version:	145	version.
84		146
85	assert (("libev version mismatch",	147	assert (("libev version mismatch",
86	ev_version_major () == EV_VERSION_MAJOR	148	ev_version_major () == EV_VERSION_MAJOR
87	&& ev_version_minor () >= EV_VERSION_MINOR));	149	&& ev_version_minor () >= EV_VERSION_MINOR));
88		150
…		…
118		180
119	See the description of C<ev_embed> watchers for more info.	181	See the description of C<ev_embed> watchers for more info.
120		182
121	=item ev_set_allocator (void *(*cb)(void *ptr, long size))	183	=item ev_set_allocator (void *(*cb)(void *ptr, long size))
122		184
123	Sets the allocation function to use (the prototype is similar to the	185	Sets the allocation function to use (the prototype is similar - the
124	realloc C function, the semantics are identical). It is used to allocate	186	semantics is identical - to the realloc C function). It is used to
125	and free memory (no surprises here). If it returns zero when memory	187	allocate and free memory (no surprises here). If it returns zero when
126	needs to be allocated, the library might abort or take some potentially	188	memory needs to be allocated, the library might abort or take some
127	destructive action. The default is your system realloc function.	189	potentially destructive action. The default is your system realloc
		190	function.
128		191
129	You could override this function in high-availability programs to, say,	192	You could override this function in high-availability programs to, say,
130	free some memory if it cannot allocate memory, to use a special allocator,	193	free some memory if it cannot allocate memory, to use a special allocator,
131	or even to sleep a while and retry until some memory is available.	194	or even to sleep a while and retry until some memory is available.
132		195
133	Example: replace the libev allocator with one that waits a bit and then	196	Example: Replace the libev allocator with one that waits a bit and then
134	retries: better than mine).	197	retries).
135		198
136	static void *	199	static void *
137	persistent_realloc (void *ptr, long size)	200	persistent_realloc (void *ptr, size_t size)
138	{	201	{
139	for (;;)	202	for (;;)
140	{	203	{
141	void *newptr = realloc (ptr, size);	204	void *newptr = realloc (ptr, size);
142		205
…		…
158	callback is set, then libev will expect it to remedy the sitution, no	221	callback is set, then libev will expect it to remedy the sitution, no
159	matter what, when it returns. That is, libev will generally retry the	222	matter what, when it returns. That is, libev will generally retry the
160	requested operation, or, if the condition doesn't go away, do bad stuff	223	requested operation, or, if the condition doesn't go away, do bad stuff
161	(such as abort).	224	(such as abort).
162		225
163	Example: do the same thing as libev does internally:	226	Example: This is basically the same thing that libev does internally, too.
164		227
165	static void	228	static void
166	fatal_error (const char *msg)	229	fatal_error (const char *msg)
167	{	230	{
168	perror (msg);	231	perror (msg);
…		…
197	flags. If that is troubling you, check C<ev_backend ()> afterwards).	260	flags. If that is troubling you, check C<ev_backend ()> afterwards).
198		261
199	If you don't know what event loop to use, use the one returned from this	262	If you don't know what event loop to use, use the one returned from this
200	function.	263	function.
201		264
		265	The default loop is the only loop that can handle C<ev_signal> and
		266	C<ev_child> watchers, and to do this, it always registers a handler
		267	for C<SIGCHLD>. If this is a problem for your app you can either
		268	create a dynamic loop with C<ev_loop_new> that doesn't do that, or you
		269	can simply overwrite the C<SIGCHLD> signal handler I<after> calling
		270	C<ev_default_init>.
		271
202	The flags argument can be used to specify special behaviour or specific	272	The flags argument can be used to specify special behaviour or specific
203	backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>).	273	backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>).
204		274
205	The following flags are supported:	275	The following flags are supported:
206		276
…		…
218	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	288	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
219	override the flags completely if it is found in the environment. This is	289	override the flags completely if it is found in the environment. This is
220	useful to try out specific backends to test their performance, or to work	290	useful to try out specific backends to test their performance, or to work
221	around bugs.	291	around bugs.
222		292
		293	=item C<EVFLAG_FORKCHECK>
		294
		295	Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after
		296	a fork, you can also make libev check for a fork in each iteration by
		297	enabling this flag.
		298
		299	This works by calling C<getpid ()> on every iteration of the loop,
		300	and thus this might slow down your event loop if you do a lot of loop
		301	iterations and little real work, but is usually not noticeable (on my
		302	Linux system for example, C<getpid> is actually a simple 5-insn sequence
		303	without a syscall and thus I<very> fast, but my Linux system also has
		304	C<pthread_atfork> which is even faster).
		305
		306	The big advantage of this flag is that you can forget about fork (and
		307	forget about forgetting to tell libev about forking) when you use this
		308	flag.
		309
		310	This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS>
		311	environment variable.
		312
223	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	313	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
224		314
225	This is your standard select(2) backend. Not I<completely> standard, as	315	This is your standard select(2) backend. Not I<completely> standard, as
226	libev tries to roll its own fd_set with no limits on the number of fds,	316	libev tries to roll its own fd_set with no limits on the number of fds,
227	but if that fails, expect a fairly low limit on the number of fds when	317	but if that fails, expect a fairly low limit on the number of fds when
228	using this backend. It doesn't scale too well (O(highest_fd)), but its usually	318	using this backend. It doesn't scale too well (O(highest_fd)), but its
229	the fastest backend for a low number of fds.	319	usually the fastest backend for a low number of (low-numbered :) fds.
		320
		321	To get good performance out of this backend you need a high amount of
		322	parallelity (most of the file descriptors should be busy). If you are
		323	writing a server, you should C<accept ()> in a loop to accept as many
		324	connections as possible during one iteration. You might also want to have
		325	a look at C<ev_set_io_collect_interval ()> to increase the amount of
		326	readyness notifications you get per iteration.
230		327
231	=item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows)	328	=item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows)
232		329
233	And this is your standard poll(2) backend. It's more complicated than	330	And this is your standard poll(2) backend. It's more complicated
234	select, but handles sparse fds better and has no artificial limit on the	331	than select, but handles sparse fds better and has no artificial
235	number of fds you can use (except it will slow down considerably with a	332	limit on the number of fds you can use (except it will slow down
236	lot of inactive fds). It scales similarly to select, i.e. O(total_fds).	333	considerably with a lot of inactive fds). It scales similarly to select,
		334	i.e. O(total_fds). See the entry for C<EVBACKEND_SELECT>, above, for
		335	performance tips.
237		336
238	=item C<EVBACKEND_EPOLL> (value 4, Linux)	337	=item C<EVBACKEND_EPOLL> (value 4, Linux)
239		338
240	For few fds, this backend is a bit little slower than poll and select,	339	For few fds, this backend is a bit little slower than poll and select,
241	but it scales phenomenally better. While poll and select usually scale like	340	but it scales phenomenally better. While poll and select usually scale
242	O(total_fds) where n is the total number of fds (or the highest fd), epoll scales	341	like O(total_fds) where n is the total number of fds (or the highest fd),
243	either O(1) or O(active_fds).	342	epoll scales either O(1) or O(active_fds). The epoll design has a number
		343	of shortcomings, such as silently dropping events in some hard-to-detect
		344	cases and rewiring a syscall per fd change, no fork support and bad
		345	support for dup.
244		346
245	While stopping and starting an I/O watcher in the same iteration will	347	While stopping, setting and starting an I/O watcher in the same iteration
246	result in some caching, there is still a syscall per such incident	348	will result in some caching, there is still a syscall per such incident
247	(because the fd could point to a different file description now), so its	349	(because the fd could point to a different file description now), so its
248	best to avoid that. Also, dup()ed file descriptors might not work very	350	best to avoid that. Also, C<dup ()>'ed file descriptors might not work
249	well if you register events for both fds.	351	very well if you register events for both fds.
250		352
251	Please note that epoll sometimes generates spurious notifications, so you	353	Please note that epoll sometimes generates spurious notifications, so you
252	need to use non-blocking I/O or other means to avoid blocking when no data	354	need to use non-blocking I/O or other means to avoid blocking when no data
253	(or space) is available.	355	(or space) is available.
254		356
		357	Best performance from this backend is achieved by not unregistering all
		358	watchers for a file descriptor until it has been closed, if possible, i.e.
		359	keep at least one watcher active per fd at all times.
		360
		361	While nominally embeddeble in other event loops, this feature is broken in
		362	all kernel versions tested so far.
		363
255	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)	364	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)
256		365
257	Kqueue deserves special mention, as at the time of this writing, it	366	Kqueue deserves special mention, as at the time of this writing, it
258	was broken on all BSDs except NetBSD (usually it doesn't work with	367	was broken on all BSDs except NetBSD (usually it doesn't work reliably
259	anything but sockets and pipes, except on Darwin, where of course its	368	with anything but sockets and pipes, except on Darwin, where of course
260	completely useless). For this reason its not being "autodetected"	369	it's completely useless). For this reason it's not being "autodetected"
261	unless you explicitly specify it explicitly in the flags (i.e. using	370	unless you explicitly specify it explicitly in the flags (i.e. using
262	C<EVBACKEND_KQUEUE>).	371	C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough)
		372	system like NetBSD.
		373
		374	You still can embed kqueue into a normal poll or select backend and use it
		375	only for sockets (after having made sure that sockets work with kqueue on
		376	the target platform). See C<ev_embed> watchers for more info.
263		377
264	It scales in the same way as the epoll backend, but the interface to the	378	It scales in the same way as the epoll backend, but the interface to the
265	kernel is more efficient (which says nothing about its actual speed, of	379	kernel is more efficient (which says nothing about its actual speed, of
266	course). While starting and stopping an I/O watcher does not cause an	380	course). While stopping, setting and starting an I/O watcher does never
267	extra syscall as with epoll, it still adds up to four event changes per	381	cause an extra syscall as with C<EVBACKEND_EPOLL>, it still adds up to
268	incident, so its best to avoid that.	382	two event changes per incident, support for C<fork ()> is very bad and it
		383	drops fds silently in similarly hard-to-detect cases.
		384
		385	This backend usually performs well under most conditions.
		386
		387	While nominally embeddable in other event loops, this doesn't work
		388	everywhere, so you might need to test for this. And since it is broken
		389	almost everywhere, you should only use it when you have a lot of sockets
		390	(for which it usually works), by embedding it into another event loop
		391	(e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>) and using it only for
		392	sockets.
269		393
270	=item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8)	394	=item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8)
271		395
272	This is not implemented yet (and might never be).	396	This is not implemented yet (and might never be, unless you send me an
		397	implementation). According to reports, C</dev/poll> only supports sockets
		398	and is not embeddable, which would limit the usefulness of this backend
		399	immensely.
273		400
274	=item C<EVBACKEND_PORT> (value 32, Solaris 10)	401	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
275		402
276	This uses the Solaris 10 port mechanism. As with everything on Solaris,	403	This uses the Solaris 10 event port mechanism. As with everything on Solaris,
277	it's really slow, but it still scales very well (O(active_fds)).	404	it's really slow, but it still scales very well (O(active_fds)).
278		405
279	Please note that solaris ports can result in a lot of spurious	406	Please note that solaris event ports can deliver a lot of spurious
280	notifications, so you need to use non-blocking I/O or other means to avoid	407	notifications, so you need to use non-blocking I/O or other means to avoid
281	blocking when no data (or space) is available.	408	blocking when no data (or space) is available.
		409
		410	While this backend scales well, it requires one system call per active
		411	file descriptor per loop iteration. For small and medium numbers of file
		412	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend
		413	might perform better.
		414
		415	On the positive side, ignoring the spurious readyness notifications, this
		416	backend actually performed to specification in all tests and is fully
		417	embeddable, which is a rare feat among the OS-specific backends.
282		418
283	=item C<EVBACKEND_ALL>	419	=item C<EVBACKEND_ALL>
284		420
285	Try all backends (even potentially broken ones that wouldn't be tried	421	Try all backends (even potentially broken ones that wouldn't be tried
286	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as	422	with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as
287	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.	423	C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>.
288		424
		425	It is definitely not recommended to use this flag.
		426
289	=back	427	=back
290		428
291	If one or more of these are ored into the flags value, then only these	429	If one or more of these are ored into the flags value, then only these
292	backends will be tried (in the reverse order as given here). If none are	430	backends will be tried (in the reverse order as listed here). If none are
293	specified, most compiled-in backend will be tried, usually in reverse	431	specified, all backends in C<ev_recommended_backends ()> will be tried.
294	order of their flag values :)
295		432
296	The most typical usage is like this:	433	The most typical usage is like this:
297		434
298	if (!ev_default_loop (0))	435	if (!ev_default_loop (0))
299	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");	436	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
…		…
314	Similar to C<ev_default_loop>, but always creates a new event loop that is	451	Similar to C<ev_default_loop>, but always creates a new event loop that is
315	always distinct from the default loop. Unlike the default loop, it cannot	452	always distinct from the default loop. Unlike the default loop, it cannot
316	handle signal and child watchers, and attempts to do so will be greeted by	453	handle signal and child watchers, and attempts to do so will be greeted by
317	undefined behaviour (or a failed assertion if assertions are enabled).	454	undefined behaviour (or a failed assertion if assertions are enabled).
318		455
319	Example: try to create a event loop that uses epoll and nothing else.	456	Example: Try to create a event loop that uses epoll and nothing else.
320		457
321	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	458	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
322	if (!epoller)	459	if (!epoller)
323	fatal ("no epoll found here, maybe it hides under your chair");	460	fatal ("no epoll found here, maybe it hides under your chair");
324		461
…		…
327	Destroys the default loop again (frees all memory and kernel state	464	Destroys the default loop again (frees all memory and kernel state
328	etc.). None of the active event watchers will be stopped in the normal	465	etc.). None of the active event watchers will be stopped in the normal
329	sense, so e.g. C<ev_is_active> might still return true. It is your	466	sense, so e.g. C<ev_is_active> might still return true. It is your
330	responsibility to either stop all watchers cleanly yoursef I<before>	467	responsibility to either stop all watchers cleanly yoursef I<before>
331	calling this function, or cope with the fact afterwards (which is usually	468	calling this function, or cope with the fact afterwards (which is usually
332	the easiest thing, youc na just ignore the watchers and/or C<free ()> them	469	the easiest thing, you can just ignore the watchers and/or C<free ()> them
333	for example).	470	for example).
		471
		472	Note that certain global state, such as signal state, will not be freed by
		473	this function, and related watchers (such as signal and child watchers)
		474	would need to be stopped manually.
		475
		476	In general it is not advisable to call this function except in the
		477	rare occasion where you really need to free e.g. the signal handling
		478	pipe fds. If you need dynamically allocated loops it is better to use
		479	C<ev_loop_new> and C<ev_loop_destroy>).
334		480
335	=item ev_loop_destroy (loop)	481	=item ev_loop_destroy (loop)
336		482
337	Like C<ev_default_destroy>, but destroys an event loop created by an	483	Like C<ev_default_destroy>, but destroys an event loop created by an
338	earlier call to C<ev_loop_new>.	484	earlier call to C<ev_loop_new>.
339		485
340	=item ev_default_fork ()	486	=item ev_default_fork ()
341		487
		488	This function sets a flag that causes subsequent C<ev_loop> iterations
342	This function reinitialises the kernel state for backends that have	489	to reinitialise the kernel state for backends that have one. Despite the
343	one. Despite the name, you can call it anytime, but it makes most sense	490	name, you can call it anytime, but it makes most sense after forking, in
344	after forking, in either the parent or child process (or both, but that	491	the child process (or both child and parent, but that again makes little
345	again makes little sense).	492	sense). You I<must> call it in the child before using any of the libev
		493	functions, and it will only take effect at the next C<ev_loop> iteration.
346		494
347	You I<must> call this function in the child process after forking if and	495	On the other hand, you only need to call this function in the child
348	only if you want to use the event library in both processes. If you just	496	process if and only if you want to use the event library in the child. If
349	fork+exec, you don't have to call it.	497	you just fork+exec, you don't have to call it at all.
350		498
351	The function itself is quite fast and it's usually not a problem to call	499	The function itself is quite fast and it's usually not a problem to call
352	it just in case after a fork. To make this easy, the function will fit in	500	it just in case after a fork. To make this easy, the function will fit in
353	quite nicely into a call to C<pthread_atfork>:	501	quite nicely into a call to C<pthread_atfork>:
354		502
355	pthread_atfork (0, 0, ev_default_fork);	503	pthread_atfork (0, 0, ev_default_fork);
356		504
357	At the moment, C<EVBACKEND_SELECT> and C<EVBACKEND_POLL> are safe to use
358	without calling this function, so if you force one of those backends you
359	do not need to care.
360
361	=item ev_loop_fork (loop)	505	=item ev_loop_fork (loop)
362		506
363	Like C<ev_default_fork>, but acts on an event loop created by	507	Like C<ev_default_fork>, but acts on an event loop created by
364	C<ev_loop_new>. Yes, you have to call this on every allocated event loop	508	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
365	after fork, and how you do this is entirely your own problem.	509	after fork, and how you do this is entirely your own problem.
		510
		511	=item unsigned int ev_loop_count (loop)
		512
		513	Returns the count of loop iterations for the loop, which is identical to
		514	the number of times libev did poll for new events. It starts at C<0> and
		515	happily wraps around with enough iterations.
		516
		517	This value can sometimes be useful as a generation counter of sorts (it
		518	"ticks" the number of loop iterations), as it roughly corresponds with
		519	C<ev_prepare> and C<ev_check> calls.
366		520
367	=item unsigned int ev_backend (loop)	521	=item unsigned int ev_backend (loop)
368		522
369	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	523	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
370	use.	524	use.
…		…
373		527
374	Returns the current "event loop time", which is the time the event loop	528	Returns the current "event loop time", which is the time the event loop
375	received events and started processing them. This timestamp does not	529	received events and started processing them. This timestamp does not
376	change as long as callbacks are being processed, and this is also the base	530	change as long as callbacks are being processed, and this is also the base
377	time used for relative timers. You can treat it as the timestamp of the	531	time used for relative timers. You can treat it as the timestamp of the
378	event occuring (or more correctly, libev finding out about it).	532	event occurring (or more correctly, libev finding out about it).
379		533
380	=item ev_loop (loop, int flags)	534	=item ev_loop (loop, int flags)
381		535
382	Finally, this is it, the event handler. This function usually is called	536	Finally, this is it, the event handler. This function usually is called
383	after you initialised all your watchers and you want to start handling	537	after you initialised all your watchers and you want to start handling
…		…
404	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is	558	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is
405	usually a better approach for this kind of thing.	559	usually a better approach for this kind of thing.
406		560
407	Here are the gory details of what C<ev_loop> does:	561	Here are the gory details of what C<ev_loop> does:
408		562
409	* If there are no active watchers (reference count is zero), return.	563	- Before the first iteration, call any pending watchers.
410	- Queue prepare watchers and then call all outstanding watchers.	564	* If EVFLAG_FORKCHECK was used, check for a fork.
		565	- If a fork was detected, queue and call all fork watchers.
		566	- Queue and call all prepare watchers.
411	- If we have been forked, recreate the kernel state.	567	- If we have been forked, recreate the kernel state.
412	- Update the kernel state with all outstanding changes.	568	- Update the kernel state with all outstanding changes.
413	- Update the "event loop time".	569	- Update the "event loop time".
414	- Calculate for how long to block.	570	- Calculate for how long to sleep or block, if at all
		571	(active idle watchers, EVLOOP_NONBLOCK or not having
		572	any active watchers at all will result in not sleeping).
		573	- Sleep if the I/O and timer collect interval say so.
415	- Block the process, waiting for any events.	574	- Block the process, waiting for any events.
416	- Queue all outstanding I/O (fd) events.	575	- Queue all outstanding I/O (fd) events.
417	- Update the "event loop time" and do time jump handling.	576	- Update the "event loop time" and do time jump handling.
418	- Queue all outstanding timers.	577	- Queue all outstanding timers.
419	- Queue all outstanding periodics.	578	- Queue all outstanding periodics.
420	- If no events are pending now, queue all idle watchers.	579	- If no events are pending now, queue all idle watchers.
421	- Queue all check watchers.	580	- Queue all check watchers.
422	- Call all queued watchers in reverse order (i.e. check watchers first).	581	- Call all queued watchers in reverse order (i.e. check watchers first).
423	Signals and child watchers are implemented as I/O watchers, and will	582	Signals and child watchers are implemented as I/O watchers, and will
424	be handled here by queueing them when their watcher gets executed.	583	be handled here by queueing them when their watcher gets executed.
425	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	584	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
426	were used, return, otherwise continue with step *.	585	were used, or there are no active watchers, return, otherwise
		586	continue with step *.
427		587
428	Example: queue some jobs and then loop until no events are outsanding	588	Example: Queue some jobs and then loop until no events are outstanding
429	anymore.	589	anymore.
430		590
431	... queue jobs here, make sure they register event watchers as long	591	... queue jobs here, make sure they register event watchers as long
432	... as they still have work to do (even an idle watcher will do..)	592	... as they still have work to do (even an idle watcher will do..)
433	ev_loop (my_loop, 0);	593	ev_loop (my_loop, 0);
…		…
437		597
438	Can be used to make a call to C<ev_loop> return early (but only after it	598	Can be used to make a call to C<ev_loop> return early (but only after it
439	has processed all outstanding events). The C<how> argument must be either	599	has processed all outstanding events). The C<how> argument must be either
440	C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or	600	C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or
441	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.	601	C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return.
		602
		603	This "unloop state" will be cleared when entering C<ev_loop> again.
442		604
443	=item ev_ref (loop)	605	=item ev_ref (loop)
444		606
445	=item ev_unref (loop)	607	=item ev_unref (loop)
446		608
…		…
451	returning, ev_unref() after starting, and ev_ref() before stopping it. For	613	returning, ev_unref() after starting, and ev_ref() before stopping it. For
452	example, libev itself uses this for its internal signal pipe: It is not	614	example, libev itself uses this for its internal signal pipe: It is not
453	visible to the libev user and should not keep C<ev_loop> from exiting if	615	visible to the libev user and should not keep C<ev_loop> from exiting if
454	no event watchers registered by it are active. It is also an excellent	616	no event watchers registered by it are active. It is also an excellent
455	way to do this for generic recurring timers or from within third-party	617	way to do this for generic recurring timers or from within third-party
456	libraries. Just remember to I<unref after start> and I<ref before stop>.	618	libraries. Just remember to I<unref after start> and I<ref before stop>
		619	(but only if the watcher wasn't active before, or was active before,
		620	respectively).
457		621
458	Example: create a signal watcher, but keep it from keeping C<ev_loop>	622	Example: Create a signal watcher, but keep it from keeping C<ev_loop>
459	running when nothing else is active.	623	running when nothing else is active.
460		624
461	struct dv_signal exitsig;	625	struct ev_signal exitsig;
462	ev_signal_init (&exitsig, sig_cb, SIGINT);	626	ev_signal_init (&exitsig, sig_cb, SIGINT);
463	ev_signal_start (myloop, &exitsig);	627	ev_signal_start (loop, &exitsig);
464	evf_unref (myloop);	628	evf_unref (loop);
465		629
466	Example: for some weird reason, unregister the above signal handler again.	630	Example: For some weird reason, unregister the above signal handler again.
467		631
468	ev_ref (myloop);	632	ev_ref (loop);
469	ev_signal_stop (myloop, &exitsig);	633	ev_signal_stop (loop, &exitsig);
		634
		635	=item ev_set_io_collect_interval (loop, ev_tstamp interval)
		636
		637	=item ev_set_timeout_collect_interval (loop, ev_tstamp interval)
		638
		639	These advanced functions influence the time that libev will spend waiting
		640	for events. Both are by default C<0>, meaning that libev will try to
		641	invoke timer/periodic callbacks and I/O callbacks with minimum latency.
		642
		643	Setting these to a higher value (the C<interval> I<must> be >= C<0>)
		644	allows libev to delay invocation of I/O and timer/periodic callbacks to
		645	increase efficiency of loop iterations.
		646
		647	The background is that sometimes your program runs just fast enough to
		648	handle one (or very few) event(s) per loop iteration. While this makes
		649	the program responsive, it also wastes a lot of CPU time to poll for new
		650	events, especially with backends like C<select ()> which have a high
		651	overhead for the actual polling but can deliver many events at once.
		652
		653	By setting a higher I<io collect interval> you allow libev to spend more
		654	time collecting I/O events, so you can handle more events per iteration,
		655	at the cost of increasing latency. Timeouts (both C<ev_periodic> and
		656	C<ev_timer>) will be not affected. Setting this to a non-null value will
		657	introduce an additional C<ev_sleep ()> call into most loop iterations.
		658
		659	Likewise, by setting a higher I<timeout collect interval> you allow libev
		660	to spend more time collecting timeouts, at the expense of increased
		661	latency (the watcher callback will be called later). C<ev_io> watchers
		662	will not be affected. Setting this to a non-null value will not introduce
		663	any overhead in libev.
		664
		665	Many (busy) programs can usually benefit by setting the io collect
		666	interval to a value near C<0.1> or so, which is often enough for
		667	interactive servers (of course not for games), likewise for timeouts. It
		668	usually doesn't make much sense to set it to a lower value than C<0.01>,
		669	as this approsaches the timing granularity of most systems.
470		670
471	=back	671	=back
472		672
473		673
474	=head1 ANATOMY OF A WATCHER	674	=head1 ANATOMY OF A WATCHER
…		…
544	The signal specified in the C<ev_signal> watcher has been received by a thread.	744	The signal specified in the C<ev_signal> watcher has been received by a thread.
545		745
546	=item C<EV_CHILD>	746	=item C<EV_CHILD>
547		747
548	The pid specified in the C<ev_child> watcher has received a status change.	748	The pid specified in the C<ev_child> watcher has received a status change.
		749
		750	=item C<EV_STAT>
		751
		752	The path specified in the C<ev_stat> watcher changed its attributes somehow.
549		753
550	=item C<EV_IDLE>	754	=item C<EV_IDLE>
551		755
552	The C<ev_idle> watcher has determined that you have nothing better to do.	756	The C<ev_idle> watcher has determined that you have nothing better to do.
553		757
…		…
561	received events. Callbacks of both watcher types can start and stop as	765	received events. Callbacks of both watcher types can start and stop as
562	many watchers as they want, and all of them will be taken into account	766	many watchers as they want, and all of them will be taken into account
563	(for example, a C<ev_prepare> watcher might start an idle watcher to keep	767	(for example, a C<ev_prepare> watcher might start an idle watcher to keep
564	C<ev_loop> from blocking).	768	C<ev_loop> from blocking).
565		769
		770	=item C<EV_EMBED>
		771
		772	The embedded event loop specified in the C<ev_embed> watcher needs attention.
		773
		774	=item C<EV_FORK>
		775
		776	The event loop has been resumed in the child process after fork (see
		777	C<ev_fork>).
		778
566	=item C<EV_ERROR>	779	=item C<EV_ERROR>
567		780
568	An unspecified error has occured, the watcher has been stopped. This might	781	An unspecified error has occured, the watcher has been stopped. This might
569	happen because the watcher could not be properly started because libev	782	happen because the watcher could not be properly started because libev
570	ran out of memory, a file descriptor was found to be closed or any other	783	ran out of memory, a file descriptor was found to be closed or any other
…		…
641	=item bool ev_is_pending (ev_TYPE *watcher)	854	=item bool ev_is_pending (ev_TYPE *watcher)
642		855
643	Returns a true value iff the watcher is pending, (i.e. it has outstanding	856	Returns a true value iff the watcher is pending, (i.e. it has outstanding
644	events but its callback has not yet been invoked). As long as a watcher	857	events but its callback has not yet been invoked). As long as a watcher
645	is pending (but not active) you must not call an init function on it (but	858	is pending (but not active) you must not call an init function on it (but
646	C<ev_TYPE_set> is safe) and you must make sure the watcher is available to	859	C<ev_TYPE_set> is safe), you must not change its priority, and you must
647	libev (e.g. you cnanot C<free ()> it).	860	make sure the watcher is available to libev (e.g. you cannot C<free ()>
		861	it).
648		862
649	=item callback = ev_cb (ev_TYPE *watcher)	863	=item callback ev_cb (ev_TYPE *watcher)
650		864
651	Returns the callback currently set on the watcher.	865	Returns the callback currently set on the watcher.
652		866
653	=item ev_cb_set (ev_TYPE *watcher, callback)	867	=item ev_cb_set (ev_TYPE *watcher, callback)
654		868
655	Change the callback. You can change the callback at virtually any time	869	Change the callback. You can change the callback at virtually any time
656	(modulo threads).	870	(modulo threads).
		871
		872	=item ev_set_priority (ev_TYPE *watcher, priority)
		873
		874	=item int ev_priority (ev_TYPE *watcher)
		875
		876	Set and query the priority of the watcher. The priority is a small
		877	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>
		878	(default: C<-2>). Pending watchers with higher priority will be invoked
		879	before watchers with lower priority, but priority will not keep watchers
		880	from being executed (except for C<ev_idle> watchers).
		881
		882	This means that priorities are I<only> used for ordering callback
		883	invocation after new events have been received. This is useful, for
		884	example, to reduce latency after idling, or more often, to bind two
		885	watchers on the same event and make sure one is called first.
		886
		887	If you need to suppress invocation when higher priority events are pending
		888	you need to look at C<ev_idle> watchers, which provide this functionality.
		889
		890	You I<must not> change the priority of a watcher as long as it is active or
		891	pending.
		892
		893	The default priority used by watchers when no priority has been set is
		894	always C<0>, which is supposed to not be too high and not be too low :).
		895
		896	Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is
		897	fine, as long as you do not mind that the priority value you query might
		898	or might not have been adjusted to be within valid range.
		899
		900	=item ev_invoke (loop, ev_TYPE *watcher, int revents)
		901
		902	Invoke the C<watcher> with the given C<loop> and C<revents>. Neither
		903	C<loop> nor C<revents> need to be valid as long as the watcher callback
		904	can deal with that fact.
		905
		906	=item int ev_clear_pending (loop, ev_TYPE *watcher)
		907
		908	If the watcher is pending, this function returns clears its pending status
		909	and returns its C<revents> bitset (as if its callback was invoked). If the
		910	watcher isn't pending it does nothing and returns C<0>.
657		911
658	=back	912	=back
659		913
660		914
661	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	915	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
682	{	936	{
683	struct my_io *w = (struct my_io *)w_;	937	struct my_io *w = (struct my_io *)w_;
684	...	938	...
685	}	939	}
686		940
687	More interesting and less C-conformant ways of catsing your callback type	941	More interesting and less C-conformant ways of casting your callback type
688	have been omitted....	942	instead have been omitted.
		943
		944	Another common scenario is having some data structure with multiple
		945	watchers:
		946
		947	struct my_biggy
		948	{
		949	int some_data;
		950	ev_timer t1;
		951	ev_timer t2;
		952	}
		953
		954	In this case getting the pointer to C<my_biggy> is a bit more complicated,
		955	you need to use C<offsetof>:
		956
		957	#include <stddef.h>
		958
		959	static void
		960	t1_cb (EV_P_ struct ev_timer *w, int revents)
		961	{
		962	struct my_biggy big = (struct my_biggy *
		963	(((char *)w) - offsetof (struct my_biggy, t1));
		964	}
		965
		966	static void
		967	t2_cb (EV_P_ struct ev_timer *w, int revents)
		968	{
		969	struct my_biggy big = (struct my_biggy *
		970	(((char *)w) - offsetof (struct my_biggy, t2));
		971	}
689		972
690		973
691	=head1 WATCHER TYPES	974	=head1 WATCHER TYPES
692		975
693	This section describes each watcher in detail, but will not repeat	976	This section describes each watcher in detail, but will not repeat
694	information given in the last section.	977	information given in the last section. Any initialisation/set macros,
		978	functions and members specific to the watcher type are explained.
		979
		980	Members are additionally marked with either I<[read-only]>, meaning that,
		981	while the watcher is active, you can look at the member and expect some
		982	sensible content, but you must not modify it (you can modify it while the
		983	watcher is stopped to your hearts content), or I<[read-write]>, which
		984	means you can expect it to have some sensible content while the watcher
		985	is active, but you can also modify it. Modifying it may not do something
		986	sensible or take immediate effect (or do anything at all), but libev will
		987	not crash or malfunction in any way.
695		988
696		989
697	=head2 C<ev_io> - is this file descriptor readable or writable?	990	=head2 C<ev_io> - is this file descriptor readable or writable?
698		991
699	I/O watchers check whether a file descriptor is readable or writable	992	I/O watchers check whether a file descriptor is readable or writable
…		…
706		999
707	In general you can register as many read and/or write event watchers per	1000	In general you can register as many read and/or write event watchers per
708	fd as you want (as long as you don't confuse yourself). Setting all file	1001	fd as you want (as long as you don't confuse yourself). Setting all file
709	descriptors to non-blocking mode is also usually a good idea (but not	1002	descriptors to non-blocking mode is also usually a good idea (but not
710	required if you know what you are doing).	1003	required if you know what you are doing).
711
712	You have to be careful with dup'ed file descriptors, though. Some backends
713	(the linux epoll backend is a notable example) cannot handle dup'ed file
714	descriptors correctly if you register interest in two or more fds pointing
715	to the same underlying file/socket/etc. description (that is, they share
716	the same underlying "file open").
717		1004
718	If you must do this, then force the use of a known-to-be-good backend	1005	If you must do this, then force the use of a known-to-be-good backend
719	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and	1006	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and
720	C<EVBACKEND_POLL>).	1007	C<EVBACKEND_POLL>).
721		1008
…		…
728	it is best to always use non-blocking I/O: An extra C<read>(2) returning	1015	it is best to always use non-blocking I/O: An extra C<read>(2) returning
729	C<EAGAIN> is far preferable to a program hanging until some data arrives.	1016	C<EAGAIN> is far preferable to a program hanging until some data arrives.
730		1017
731	If you cannot run the fd in non-blocking mode (for example you should not	1018	If you cannot run the fd in non-blocking mode (for example you should not
732	play around with an Xlib connection), then you have to seperately re-test	1019	play around with an Xlib connection), then you have to seperately re-test
733	wether a file descriptor is really ready with a known-to-be good interface	1020	whether a file descriptor is really ready with a known-to-be good interface
734	such as poll (fortunately in our Xlib example, Xlib already does this on	1021	such as poll (fortunately in our Xlib example, Xlib already does this on
735	its own, so its quite safe to use).	1022	its own, so its quite safe to use).
		1023
		1024	=head3 The special problem of disappearing file descriptors
		1025
		1026	Some backends (e.g. kqueue, epoll) need to be told about closing a file
		1027	descriptor (either by calling C<close> explicitly or by any other means,
		1028	such as C<dup>). The reason is that you register interest in some file
		1029	descriptor, but when it goes away, the operating system will silently drop
		1030	this interest. If another file descriptor with the same number then is
		1031	registered with libev, there is no efficient way to see that this is, in
		1032	fact, a different file descriptor.
		1033
		1034	To avoid having to explicitly tell libev about such cases, libev follows
		1035	the following policy: Each time C<ev_io_set> is being called, libev
		1036	will assume that this is potentially a new file descriptor, otherwise
		1037	it is assumed that the file descriptor stays the same. That means that
		1038	you I<have> to call C<ev_io_set> (or C<ev_io_init>) when you change the
		1039	descriptor even if the file descriptor number itself did not change.
		1040
		1041	This is how one would do it normally anyway, the important point is that
		1042	the libev application should not optimise around libev but should leave
		1043	optimisations to libev.
		1044
		1045	=head3 The special problem of dup'ed file descriptors
		1046
		1047	Some backends (e.g. epoll), cannot register events for file descriptors,
		1048	but only events for the underlying file descriptions. That means when you
		1049	have C<dup ()>'ed file descriptors or weirder constellations, and register
		1050	events for them, only one file descriptor might actually receive events.
		1051
		1052	There is no workaround possible except not registering events
		1053	for potentially C<dup ()>'ed file descriptors, or to resort to
		1054	C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>.
		1055
		1056	=head3 The special problem of fork
		1057
		1058	Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit
		1059	useless behaviour. Libev fully supports fork, but needs to be told about
		1060	it in the child.
		1061
		1062	To support fork in your programs, you either have to call
		1063	C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child,
		1064	enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or
		1065	C<EVBACKEND_POLL>.
		1066
		1067
		1068	=head3 Watcher-Specific Functions
736		1069
737	=over 4	1070	=over 4
738		1071
739	=item ev_io_init (ev_io *, callback, int fd, int events)	1072	=item ev_io_init (ev_io *, callback, int fd, int events)
740		1073
…		…
742		1075
743	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to	1076	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to
744	rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or	1077	rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or
745	C<EV_READ | EV_WRITE> to receive the given events.	1078	C<EV_READ | EV_WRITE> to receive the given events.
746		1079
		1080	=item int fd [read-only]
		1081
		1082	The file descriptor being watched.
		1083
		1084	=item int events [read-only]
		1085
		1086	The events being watched.
		1087
747	=back	1088	=back
748		1089
		1090	=head3 Examples
		1091
749	Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well	1092	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well
750	readable, but only once. Since it is likely line-buffered, you could	1093	readable, but only once. Since it is likely line-buffered, you could
751	attempt to read a whole line in the callback:	1094	attempt to read a whole line in the callback.
752		1095
753	static void	1096	static void
754	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1097	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
755	{	1098	{
756	ev_io_stop (loop, w);	1099	ev_io_stop (loop, w);
…		…
786		1129
787	The callback is guarenteed to be invoked only when its timeout has passed,	1130	The callback is guarenteed to be invoked only when its timeout has passed,
788	but if multiple timers become ready during the same loop iteration then	1131	but if multiple timers become ready during the same loop iteration then
789	order of execution is undefined.	1132	order of execution is undefined.
790		1133
		1134	=head3 Watcher-Specific Functions and Data Members
		1135
791	=over 4	1136	=over 4
792		1137
793	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	1138	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
794		1139
795	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)	1140	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)
…		…
808	=item ev_timer_again (loop)	1153	=item ev_timer_again (loop)
809		1154
810	This will act as if the timer timed out and restart it again if it is	1155	This will act as if the timer timed out and restart it again if it is
811	repeating. The exact semantics are:	1156	repeating. The exact semantics are:
812		1157
		1158	If the timer is pending, its pending status is cleared.
		1159
813	If the timer is started but nonrepeating, stop it.	1160	If the timer is started but nonrepeating, stop it (as if it timed out).
814		1161
815	If the timer is repeating, either start it if necessary (with the repeat	1162	If the timer is repeating, either start it if necessary (with the
816	value), or reset the running timer to the repeat value.	1163	C<repeat> value), or reset the running timer to the C<repeat> value.
817		1164
818	This sounds a bit complicated, but here is a useful and typical	1165	This sounds a bit complicated, but here is a useful and typical
819	example: Imagine you have a tcp connection and you want a so-called idle	1166	example: Imagine you have a tcp connection and you want a so-called idle
820	timeout, that is, you want to be called when there have been, say, 60	1167	timeout, that is, you want to be called when there have been, say, 60
821	seconds of inactivity on the socket. The easiest way to do this is to	1168	seconds of inactivity on the socket. The easiest way to do this is to
822	configure an C<ev_timer> with after=repeat=60 and calling ev_timer_again each	1169	configure an C<ev_timer> with a C<repeat> value of C<60> and then call
823	time you successfully read or write some data. If you go into an idle	1170	C<ev_timer_again> each time you successfully read or write some data. If
824	state where you do not expect data to travel on the socket, you can stop	1171	you go into an idle state where you do not expect data to travel on the
825	the timer, and again will automatically restart it if need be.	1172	socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will
		1173	automatically restart it if need be.
		1174
		1175	That means you can ignore the C<after> value and C<ev_timer_start>
		1176	altogether and only ever use the C<repeat> value and C<ev_timer_again>:
		1177
		1178	ev_timer_init (timer, callback, 0., 5.);
		1179	ev_timer_again (loop, timer);
		1180	...
		1181	timer->again = 17.;
		1182	ev_timer_again (loop, timer);
		1183	...
		1184	timer->again = 10.;
		1185	ev_timer_again (loop, timer);
		1186
		1187	This is more slightly efficient then stopping/starting the timer each time
		1188	you want to modify its timeout value.
		1189
		1190	=item ev_tstamp repeat [read-write]
		1191
		1192	The current C<repeat> value. Will be used each time the watcher times out
		1193	or C<ev_timer_again> is called and determines the next timeout (if any),
		1194	which is also when any modifications are taken into account.
826		1195
827	=back	1196	=back
828		1197
		1198	=head3 Examples
		1199
829	Example: create a timer that fires after 60 seconds.	1200	Example: Create a timer that fires after 60 seconds.
830		1201
831	static void	1202	static void
832	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1203	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
833	{	1204	{
834	.. one minute over, w is actually stopped right here	1205	.. one minute over, w is actually stopped right here
…		…
836		1207
837	struct ev_timer mytimer;	1208	struct ev_timer mytimer;
838	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1209	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
839	ev_timer_start (loop, &mytimer);	1210	ev_timer_start (loop, &mytimer);
840		1211
841	Example: create a timeout timer that times out after 10 seconds of	1212	Example: Create a timeout timer that times out after 10 seconds of
842	inactivity.	1213	inactivity.
843		1214
844	static void	1215	static void
845	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1216	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
846	{	1217	{
…		…
866	but on wallclock time (absolute time). You can tell a periodic watcher	1237	but on wallclock time (absolute time). You can tell a periodic watcher
867	to trigger "at" some specific point in time. For example, if you tell a	1238	to trigger "at" some specific point in time. For example, if you tell a
868	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()	1239	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()
869	+ 10.>) and then reset your system clock to the last year, then it will	1240	+ 10.>) and then reset your system clock to the last year, then it will
870	take a year to trigger the event (unlike an C<ev_timer>, which would trigger	1241	take a year to trigger the event (unlike an C<ev_timer>, which would trigger
871	roughly 10 seconds later and of course not if you reset your system time	1242	roughly 10 seconds later).
872	again).
873		1243
874	They can also be used to implement vastly more complex timers, such as	1244	They can also be used to implement vastly more complex timers, such as
875	triggering an event on eahc midnight, local time.	1245	triggering an event on each midnight, local time or other, complicated,
		1246	rules.
876		1247
877	As with timers, the callback is guarenteed to be invoked only when the	1248	As with timers, the callback is guarenteed to be invoked only when the
878	time (C<at>) has been passed, but if multiple periodic timers become ready	1249	time (C<at>) has been passed, but if multiple periodic timers become ready
879	during the same loop iteration then order of execution is undefined.	1250	during the same loop iteration then order of execution is undefined.
880		1251
		1252	=head3 Watcher-Specific Functions and Data Members
		1253
881	=over 4	1254	=over 4
882		1255
883	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)	1256	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)
884		1257
885	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)	1258	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)
…		…
887	Lots of arguments, lets sort it out... There are basically three modes of	1260	Lots of arguments, lets sort it out... There are basically three modes of
888	operation, and we will explain them from simplest to complex:	1261	operation, and we will explain them from simplest to complex:
889		1262
890	=over 4	1263	=over 4
891		1264
892	=item * absolute timer (interval = reschedule_cb = 0)	1265	=item * absolute timer (at = time, interval = reschedule_cb = 0)
893		1266
894	In this configuration the watcher triggers an event at the wallclock time	1267	In this configuration the watcher triggers an event at the wallclock time
895	C<at> and doesn't repeat. It will not adjust when a time jump occurs,	1268	C<at> and doesn't repeat. It will not adjust when a time jump occurs,
896	that is, if it is to be run at January 1st 2011 then it will run when the	1269	that is, if it is to be run at January 1st 2011 then it will run when the
897	system time reaches or surpasses this time.	1270	system time reaches or surpasses this time.
898		1271
899	=item * non-repeating interval timer (interval > 0, reschedule_cb = 0)	1272	=item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
900		1273
901	In this mode the watcher will always be scheduled to time out at the next	1274	In this mode the watcher will always be scheduled to time out at the next
902	C<at + N * interval> time (for some integer N) and then repeat, regardless	1275	C<at + N * interval> time (for some integer N, which can also be negative)
903	of any time jumps.	1276	and then repeat, regardless of any time jumps.
904		1277
905	This can be used to create timers that do not drift with respect to system	1278	This can be used to create timers that do not drift with respect to system
906	time:	1279	time:
907		1280
908	ev_periodic_set (&periodic, 0., 3600., 0);	1281	ev_periodic_set (&periodic, 0., 3600., 0);
…		…
914		1287
915	Another way to think about it (for the mathematically inclined) is that	1288	Another way to think about it (for the mathematically inclined) is that
916	C<ev_periodic> will try to run the callback in this mode at the next possible	1289	C<ev_periodic> will try to run the callback in this mode at the next possible
917	time where C<time = at (mod interval)>, regardless of any time jumps.	1290	time where C<time = at (mod interval)>, regardless of any time jumps.
918		1291
		1292	For numerical stability it is preferable that the C<at> value is near
		1293	C<ev_now ()> (the current time), but there is no range requirement for
		1294	this value.
		1295
919	=item * manual reschedule mode (reschedule_cb = callback)	1296	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
920		1297
921	In this mode the values for C<interval> and C<at> are both being	1298	In this mode the values for C<interval> and C<at> are both being
922	ignored. Instead, each time the periodic watcher gets scheduled, the	1299	ignored. Instead, each time the periodic watcher gets scheduled, the
923	reschedule callback will be called with the watcher as first, and the	1300	reschedule callback will be called with the watcher as first, and the
924	current time as second argument.	1301	current time as second argument.
925		1302
926	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,	1303	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,
927	ever, or make any event loop modifications>. If you need to stop it,	1304	ever, or make any event loop modifications>. If you need to stop it,
928	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by	1305	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by
929	starting a prepare watcher).	1306	starting an C<ev_prepare> watcher, which is legal).
930		1307
931	Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w,	1308	Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w,
932	ev_tstamp now)>, e.g.:	1309	ev_tstamp now)>, e.g.:
933		1310
934	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	1311	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
…		…
957	Simply stops and restarts the periodic watcher again. This is only useful	1334	Simply stops and restarts the periodic watcher again. This is only useful
958	when you changed some parameters or the reschedule callback would return	1335	when you changed some parameters or the reschedule callback would return
959	a different time than the last time it was called (e.g. in a crond like	1336	a different time than the last time it was called (e.g. in a crond like
960	program when the crontabs have changed).	1337	program when the crontabs have changed).
961		1338
		1339	=item ev_tstamp offset [read-write]
		1340
		1341	When repeating, this contains the offset value, otherwise this is the
		1342	absolute point in time (the C<at> value passed to C<ev_periodic_set>).
		1343
		1344	Can be modified any time, but changes only take effect when the periodic
		1345	timer fires or C<ev_periodic_again> is being called.
		1346
		1347	=item ev_tstamp interval [read-write]
		1348
		1349	The current interval value. Can be modified any time, but changes only
		1350	take effect when the periodic timer fires or C<ev_periodic_again> is being
		1351	called.
		1352
		1353	=item ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]
		1354
		1355	The current reschedule callback, or C<0>, if this functionality is
		1356	switched off. Can be changed any time, but changes only take effect when
		1357	the periodic timer fires or C<ev_periodic_again> is being called.
		1358
		1359	=item ev_tstamp at [read-only]
		1360
		1361	When active, contains the absolute time that the watcher is supposed to
		1362	trigger next.
		1363
962	=back	1364	=back
963		1365
		1366	=head3 Examples
		1367
964	Example: call a callback every hour, or, more precisely, whenever the	1368	Example: Call a callback every hour, or, more precisely, whenever the
965	system clock is divisible by 3600. The callback invocation times have	1369	system clock is divisible by 3600. The callback invocation times have
966	potentially a lot of jittering, but good long-term stability.	1370	potentially a lot of jittering, but good long-term stability.
967		1371
968	static void	1372	static void
969	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1373	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)
…		…
973		1377
974	struct ev_periodic hourly_tick;	1378	struct ev_periodic hourly_tick;
975	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1379	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
976	ev_periodic_start (loop, &hourly_tick);	1380	ev_periodic_start (loop, &hourly_tick);
977		1381
978	Example: the same as above, but use a reschedule callback to do it:	1382	Example: The same as above, but use a reschedule callback to do it:
979		1383
980	#include <math.h>	1384	#include <math.h>
981		1385
982	static ev_tstamp	1386	static ev_tstamp
983	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1387	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
…		…
985	return fmod (now, 3600.) + 3600.;	1389	return fmod (now, 3600.) + 3600.;
986	}	1390	}
987		1391
988	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1392	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
989		1393
990	Example: call a callback every hour, starting now:	1394	Example: Call a callback every hour, starting now:
991		1395
992	struct ev_periodic hourly_tick;	1396	struct ev_periodic hourly_tick;
993	ev_periodic_init (&hourly_tick, clock_cb,	1397	ev_periodic_init (&hourly_tick, clock_cb,
994	fmod (ev_now (loop), 3600.), 3600., 0);	1398	fmod (ev_now (loop), 3600.), 3600., 0);
995	ev_periodic_start (loop, &hourly_tick);	1399	ev_periodic_start (loop, &hourly_tick);
…		…
1007	with the kernel (thus it coexists with your own signal handlers as long	1411	with the kernel (thus it coexists with your own signal handlers as long
1008	as you don't register any with libev). Similarly, when the last signal	1412	as you don't register any with libev). Similarly, when the last signal
1009	watcher for a signal is stopped libev will reset the signal handler to	1413	watcher for a signal is stopped libev will reset the signal handler to
1010	SIG_DFL (regardless of what it was set to before).	1414	SIG_DFL (regardless of what it was set to before).
1011		1415
		1416	=head3 Watcher-Specific Functions and Data Members
		1417
1012	=over 4	1418	=over 4
1013		1419
1014	=item ev_signal_init (ev_signal *, callback, int signum)	1420	=item ev_signal_init (ev_signal *, callback, int signum)
1015		1421
1016	=item ev_signal_set (ev_signal *, int signum)	1422	=item ev_signal_set (ev_signal *, int signum)
1017		1423
1018	Configures the watcher to trigger on the given signal number (usually one	1424	Configures the watcher to trigger on the given signal number (usually one
1019	of the C<SIGxxx> constants).	1425	of the C<SIGxxx> constants).
1020		1426
		1427	=item int signum [read-only]
		1428
		1429	The signal the watcher watches out for.
		1430
1021	=back	1431	=back
1022		1432
1023		1433
1024	=head2 C<ev_child> - watch out for process status changes	1434	=head2 C<ev_child> - watch out for process status changes
1025		1435
1026	Child watchers trigger when your process receives a SIGCHLD in response to	1436	Child watchers trigger when your process receives a SIGCHLD in response to
1027	some child status changes (most typically when a child of yours dies).	1437	some child status changes (most typically when a child of yours dies).
		1438
		1439	=head3 Watcher-Specific Functions and Data Members
1028		1440
1029	=over 4	1441	=over 4
1030		1442
1031	=item ev_child_init (ev_child *, callback, int pid)	1443	=item ev_child_init (ev_child *, callback, int pid)
1032		1444
…		…
1037	at the C<rstatus> member of the C<ev_child> watcher structure to see	1449	at the C<rstatus> member of the C<ev_child> watcher structure to see
1038	the status word (use the macros from C<sys/wait.h> and see your systems	1450	the status word (use the macros from C<sys/wait.h> and see your systems
1039	C<waitpid> documentation). The C<rpid> member contains the pid of the	1451	C<waitpid> documentation). The C<rpid> member contains the pid of the
1040	process causing the status change.	1452	process causing the status change.
1041		1453
		1454	=item int pid [read-only]
		1455
		1456	The process id this watcher watches out for, or C<0>, meaning any process id.
		1457
		1458	=item int rpid [read-write]
		1459
		1460	The process id that detected a status change.
		1461
		1462	=item int rstatus [read-write]
		1463
		1464	The process exit/trace status caused by C<rpid> (see your systems
		1465	C<waitpid> and C<sys/wait.h> documentation for details).
		1466
1042	=back	1467	=back
1043		1468
		1469	=head3 Examples
		1470
1044	Example: try to exit cleanly on SIGINT and SIGTERM.	1471	Example: Try to exit cleanly on SIGINT and SIGTERM.
1045		1472
1046	static void	1473	static void
1047	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)	1474	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1048	{	1475	{
1049	ev_unloop (loop, EVUNLOOP_ALL);	1476	ev_unloop (loop, EVUNLOOP_ALL);
…		…
1052	struct ev_signal signal_watcher;	1479	struct ev_signal signal_watcher;
1053	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1480	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1054	ev_signal_start (loop, &sigint_cb);	1481	ev_signal_start (loop, &sigint_cb);
1055		1482
1056		1483
		1484	=head2 C<ev_stat> - did the file attributes just change?
		1485
		1486	This watches a filesystem path for attribute changes. That is, it calls
		1487	C<stat> regularly (or when the OS says it changed) and sees if it changed
		1488	compared to the last time, invoking the callback if it did.
		1489
		1490	The path does not need to exist: changing from "path exists" to "path does
		1491	not exist" is a status change like any other. The condition "path does
		1492	not exist" is signified by the C<st_nlink> field being zero (which is
		1493	otherwise always forced to be at least one) and all the other fields of
		1494	the stat buffer having unspecified contents.
		1495
		1496	The path I<should> be absolute and I<must not> end in a slash. If it is
		1497	relative and your working directory changes, the behaviour is undefined.
		1498
		1499	Since there is no standard to do this, the portable implementation simply
		1500	calls C<stat (2)> regularly on the path to see if it changed somehow. You
		1501	can specify a recommended polling interval for this case. If you specify
		1502	a polling interval of C<0> (highly recommended!) then a I<suitable,
		1503	unspecified default> value will be used (which you can expect to be around
		1504	five seconds, although this might change dynamically). Libev will also
		1505	impose a minimum interval which is currently around C<0.1>, but thats
		1506	usually overkill.
		1507
		1508	This watcher type is not meant for massive numbers of stat watchers,
		1509	as even with OS-supported change notifications, this can be
		1510	resource-intensive.
		1511
		1512	At the time of this writing, only the Linux inotify interface is
		1513	implemented (implementing kqueue support is left as an exercise for the
		1514	reader). Inotify will be used to give hints only and should not change the
		1515	semantics of C<ev_stat> watchers, which means that libev sometimes needs
		1516	to fall back to regular polling again even with inotify, but changes are
		1517	usually detected immediately, and if the file exists there will be no
		1518	polling.
		1519
		1520	=head3 Inotify
		1521
		1522	When C<inotify (7)> support has been compiled into libev (generally only
		1523	available on Linux) and present at runtime, it will be used to speed up
		1524	change detection where possible. The inotify descriptor will be created lazily
		1525	when the first C<ev_stat> watcher is being started.
		1526
		1527	Inotify presense does not change the semantics of C<ev_stat> watchers
		1528	except that changes might be detected earlier, and in some cases, to avoid
		1529	making regular C<stat> calls. Even in the presense of inotify support
		1530	there are many cases where libev has to resort to regular C<stat> polling.
		1531
		1532	(There is no support for kqueue, as apparently it cannot be used to
		1533	implement this functionality, due to the requirement of having a file
		1534	descriptor open on the object at all times).
		1535
		1536	=head3 The special problem of stat time resolution
		1537
		1538	The C<stat ()> syscall only supports full-second resolution portably, and
		1539	even on systems where the resolution is higher, many filesystems still
		1540	only support whole seconds.
		1541
		1542	That means that, if the time is the only thing that changes, you might
		1543	miss updates: on the first update, C<ev_stat> detects a change and calls
		1544	your callback, which does something. When there is another update within
		1545	the same second, C<ev_stat> will be unable to detect it.
		1546
		1547	The solution to this is to delay acting on a change for a second (or till
		1548	the next second boundary), using a roughly one-second delay C<ev_timer>
		1549	(C<ev_timer_set (w, 0., 1.01); ev_timer_again (loop, w)>). The C<.01>
		1550	is added to work around small timing inconsistencies of some operating
		1551	systems.
		1552
		1553	=head3 Watcher-Specific Functions and Data Members
		1554
		1555	=over 4
		1556
		1557	=item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)
		1558
		1559	=item ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)
		1560
		1561	Configures the watcher to wait for status changes of the given
		1562	C<path>. The C<interval> is a hint on how quickly a change is expected to
		1563	be detected and should normally be specified as C<0> to let libev choose
		1564	a suitable value. The memory pointed to by C<path> must point to the same
		1565	path for as long as the watcher is active.
		1566
		1567	The callback will be receive C<EV_STAT> when a change was detected,
		1568	relative to the attributes at the time the watcher was started (or the
		1569	last change was detected).
		1570
		1571	=item ev_stat_stat (ev_stat *)
		1572
		1573	Updates the stat buffer immediately with new values. If you change the
		1574	watched path in your callback, you could call this fucntion to avoid
		1575	detecting this change (while introducing a race condition). Can also be
		1576	useful simply to find out the new values.
		1577
		1578	=item ev_statdata attr [read-only]
		1579
		1580	The most-recently detected attributes of the file. Although the type is of
		1581	C<ev_statdata>, this is usually the (or one of the) C<struct stat> types
		1582	suitable for your system. If the C<st_nlink> member is C<0>, then there
		1583	was some error while C<stat>ing the file.
		1584
		1585	=item ev_statdata prev [read-only]
		1586
		1587	The previous attributes of the file. The callback gets invoked whenever
		1588	C<prev> != C<attr>.
		1589
		1590	=item ev_tstamp interval [read-only]
		1591
		1592	The specified interval.
		1593
		1594	=item const char *path [read-only]
		1595
		1596	The filesystem path that is being watched.
		1597
		1598	=back
		1599
		1600	=head3 Examples
		1601
		1602	Example: Watch C</etc/passwd> for attribute changes.
		1603
		1604	static void
		1605	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
		1606	{
		1607	/* /etc/passwd changed in some way */
		1608	if (w->attr.st_nlink)
		1609	{
		1610	printf ("passwd current size %ld\n", (long)w->attr.st_size);
		1611	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
		1612	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
		1613	}
		1614	else
		1615	/* you shalt not abuse printf for puts */
		1616	puts ("wow, /etc/passwd is not there, expect problems. "
		1617	"if this is windows, they already arrived\n");
		1618	}
		1619
		1620	...
		1621	ev_stat passwd;
		1622
		1623	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);
		1624	ev_stat_start (loop, &passwd);
		1625
		1626	Example: Like above, but additionally use a one-second delay so we do not
		1627	miss updates (however, frequent updates will delay processing, too, so
		1628	one might do the work both on C<ev_stat> callback invocation I<and> on
		1629	C<ev_timer> callback invocation).
		1630
		1631	static ev_stat passwd;
		1632	static ev_timer timer;
		1633
		1634	static void
		1635	timer_cb (EV_P_ ev_timer *w, int revents)
		1636	{
		1637	ev_timer_stop (EV_A_ w);
		1638
		1639	/* now it's one second after the most recent passwd change */
		1640	}
		1641
		1642	static void
		1643	stat_cb (EV_P_ ev_stat *w, int revents)
		1644	{
		1645	/* reset the one-second timer */
		1646	ev_timer_again (EV_A_ &timer);
		1647	}
		1648
		1649	...
		1650	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);
		1651	ev_stat_start (loop, &passwd);
		1652	ev_timer_init (&timer, timer_cb, 0., 1.01);
		1653
		1654
1057	=head2 C<ev_idle> - when you've got nothing better to do...	1655	=head2 C<ev_idle> - when you've got nothing better to do...
1058		1656
1059	Idle watchers trigger events when there are no other events are pending	1657	Idle watchers trigger events when no other events of the same or higher
1060	(prepare, check and other idle watchers do not count). That is, as long	1658	priority are pending (prepare, check and other idle watchers do not
1061	as your process is busy handling sockets or timeouts (or even signals,	1659	count).
1062	imagine) it will not be triggered. But when your process is idle all idle	1660
1063	watchers are being called again and again, once per event loop iteration -	1661	That is, as long as your process is busy handling sockets or timeouts
		1662	(or even signals, imagine) of the same or higher priority it will not be
		1663	triggered. But when your process is idle (or only lower-priority watchers
		1664	are pending), the idle watchers are being called once per event loop
1064	until stopped, that is, or your process receives more events and becomes	1665	iteration - until stopped, that is, or your process receives more events
1065	busy.	1666	and becomes busy again with higher priority stuff.
1066		1667
1067	The most noteworthy effect is that as long as any idle watchers are	1668	The most noteworthy effect is that as long as any idle watchers are
1068	active, the process will not block when waiting for new events.	1669	active, the process will not block when waiting for new events.
1069		1670
1070	Apart from keeping your process non-blocking (which is a useful	1671	Apart from keeping your process non-blocking (which is a useful
1071	effect on its own sometimes), idle watchers are a good place to do	1672	effect on its own sometimes), idle watchers are a good place to do
1072	"pseudo-background processing", or delay processing stuff to after the	1673	"pseudo-background processing", or delay processing stuff to after the
1073	event loop has handled all outstanding events.	1674	event loop has handled all outstanding events.
1074		1675
		1676	=head3 Watcher-Specific Functions and Data Members
		1677
1075	=over 4	1678	=over 4
1076		1679
1077	=item ev_idle_init (ev_signal *, callback)	1680	=item ev_idle_init (ev_signal *, callback)
1078		1681
1079	Initialises and configures the idle watcher - it has no parameters of any	1682	Initialises and configures the idle watcher - it has no parameters of any
1080	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,	1683	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,
1081	believe me.	1684	believe me.
1082		1685
1083	=back	1686	=back
1084		1687
		1688	=head3 Examples
		1689
1085	Example: dynamically allocate an C<ev_idle>, start it, and in the	1690	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1086	callback, free it. Alos, use no error checking, as usual.	1691	callback, free it. Also, use no error checking, as usual.
1087		1692
1088	static void	1693	static void
1089	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)	1694	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1090	{	1695	{
1091	free (w);	1696	free (w);
…		…
1136	with priority higher than or equal to the event loop and one coroutine	1741	with priority higher than or equal to the event loop and one coroutine
1137	of lower priority, but only once, using idle watchers to keep the event	1742	of lower priority, but only once, using idle watchers to keep the event
1138	loop from blocking if lower-priority coroutines are active, thus mapping	1743	loop from blocking if lower-priority coroutines are active, thus mapping
1139	low-priority coroutines to idle/background tasks).	1744	low-priority coroutines to idle/background tasks).
1140		1745
		1746	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)
		1747	priority, to ensure that they are being run before any other watchers
		1748	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,
		1749	too) should not activate ("feed") events into libev. While libev fully
		1750	supports this, they will be called before other C<ev_check> watchers
		1751	did their job. As C<ev_check> watchers are often used to embed other
		1752	(non-libev) event loops those other event loops might be in an unusable
		1753	state until their C<ev_check> watcher ran (always remind yourself to
		1754	coexist peacefully with others).
		1755
		1756	=head3 Watcher-Specific Functions and Data Members
		1757
1141	=over 4	1758	=over 4
1142		1759
1143	=item ev_prepare_init (ev_prepare *, callback)	1760	=item ev_prepare_init (ev_prepare *, callback)
1144		1761
1145	=item ev_check_init (ev_check *, callback)	1762	=item ev_check_init (ev_check *, callback)
…		…
1148	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>	1765	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>
1149	macros, but using them is utterly, utterly and completely pointless.	1766	macros, but using them is utterly, utterly and completely pointless.
1150		1767
1151	=back	1768	=back
1152		1769
1153	Example: To include a library such as adns, you would add IO watchers	1770	=head3 Examples
1154	and a timeout watcher in a prepare handler, as required by libadns, and	1771
		1772	There are a number of principal ways to embed other event loops or modules
		1773	into libev. Here are some ideas on how to include libadns into libev
		1774	(there is a Perl module named C<EV::ADNS> that does this, which you could
		1775	use for an actually working example. Another Perl module named C<EV::Glib>
		1776	embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV
		1777	into the Glib event loop).
		1778
		1779	Method 1: Add IO watchers and a timeout watcher in a prepare handler,
1155	in a check watcher, destroy them and call into libadns. What follows is	1780	and in a check watcher, destroy them and call into libadns. What follows
1156	pseudo-code only of course:	1781	is pseudo-code only of course. This requires you to either use a low
		1782	priority for the check watcher or use C<ev_clear_pending> explicitly, as
		1783	the callbacks for the IO/timeout watchers might not have been called yet.
1157		1784
1158	static ev_io iow [nfd];	1785	static ev_io iow [nfd];
1159	static ev_timer tw;	1786	static ev_timer tw;
1160		1787
1161	static void	1788	static void
1162	io_cb (ev_loop *loop, ev_io *w, int revents)	1789	io_cb (ev_loop *loop, ev_io *w, int revents)
1163	{	1790	{
1164	// set the relevant poll flags
1165	// could also call adns_processreadable etc. here
1166	struct pollfd *fd = (struct pollfd *)w->data;
1167	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1168	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1169	}	1791	}
1170		1792
1171	// create io watchers for each fd and a timer before blocking	1793	// create io watchers for each fd and a timer before blocking
1172	static void	1794	static void
1173	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)	1795	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1174	{	1796	{
1175	int timeout = 3600000;truct pollfd fds [nfd];	1797	int timeout = 3600000;
		1798	struct pollfd fds [nfd];
1176	// actual code will need to loop here and realloc etc.	1799	// actual code will need to loop here and realloc etc.
1177	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1800	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1178		1801
1179	/* the callback is illegal, but won't be called as we stop during check */	1802	/* the callback is illegal, but won't be called as we stop during check */
1180	ev_timer_init (&tw, 0, timeout * 1e-3);	1803	ev_timer_init (&tw, 0, timeout * 1e-3);
1181	ev_timer_start (loop, &tw);	1804	ev_timer_start (loop, &tw);
1182		1805
1183	// create on ev_io per pollfd	1806	// create one ev_io per pollfd
1184	for (int i = 0; i < nfd; ++i)	1807	for (int i = 0; i < nfd; ++i)
1185	{	1808	{
1186	ev_io_init (iow + i, io_cb, fds [i].fd,	1809	ev_io_init (iow + i, io_cb, fds [i].fd,
1187	((fds [i].events & POLLIN ? EV_READ : 0)	1810	((fds [i].events & POLLIN ? EV_READ : 0)
1188	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	1811	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1189		1812
1190	fds [i].revents = 0;	1813	fds [i].revents = 0;
1191	iow [i].data = fds + i;
1192	ev_io_start (loop, iow + i);	1814	ev_io_start (loop, iow + i);
1193	}	1815	}
1194	}	1816	}
1195		1817
1196	// stop all watchers after blocking	1818	// stop all watchers after blocking
…		…
1198	adns_check_cb (ev_loop *loop, ev_check *w, int revents)	1820	adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1199	{	1821	{
1200	ev_timer_stop (loop, &tw);	1822	ev_timer_stop (loop, &tw);
1201		1823
1202	for (int i = 0; i < nfd; ++i)	1824	for (int i = 0; i < nfd; ++i)
		1825	{
		1826	// set the relevant poll flags
		1827	// could also call adns_processreadable etc. here
		1828	struct pollfd *fd = fds + i;
		1829	int revents = ev_clear_pending (iow + i);
		1830	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
		1831	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
		1832
		1833	// now stop the watcher
1203	ev_io_stop (loop, iow + i);	1834	ev_io_stop (loop, iow + i);
		1835	}
1204		1836
1205	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	1837	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1838	}
		1839
		1840	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
		1841	in the prepare watcher and would dispose of the check watcher.
		1842
		1843	Method 3: If the module to be embedded supports explicit event
		1844	notification (adns does), you can also make use of the actual watcher
		1845	callbacks, and only destroy/create the watchers in the prepare watcher.
		1846
		1847	static void
		1848	timer_cb (EV_P_ ev_timer *w, int revents)
		1849	{
		1850	adns_state ads = (adns_state)w->data;
		1851	update_now (EV_A);
		1852
		1853	adns_processtimeouts (ads, &tv_now);
		1854	}
		1855
		1856	static void
		1857	io_cb (EV_P_ ev_io *w, int revents)
		1858	{
		1859	adns_state ads = (adns_state)w->data;
		1860	update_now (EV_A);
		1861
		1862	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
		1863	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
		1864	}
		1865
		1866	// do not ever call adns_afterpoll
		1867
		1868	Method 4: Do not use a prepare or check watcher because the module you
		1869	want to embed is too inflexible to support it. Instead, youc na override
		1870	their poll function. The drawback with this solution is that the main
		1871	loop is now no longer controllable by EV. The C<Glib::EV> module does
		1872	this.
		1873
		1874	static gint
		1875	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
		1876	{
		1877	int got_events = 0;
		1878
		1879	for (n = 0; n < nfds; ++n)
		1880	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
		1881
		1882	if (timeout >= 0)
		1883	// create/start timer
		1884
		1885	// poll
		1886	ev_loop (EV_A_ 0);
		1887
		1888	// stop timer again
		1889	if (timeout >= 0)
		1890	ev_timer_stop (EV_A_ &to);
		1891
		1892	// stop io watchers again - their callbacks should have set
		1893	for (n = 0; n < nfds; ++n)
		1894	ev_io_stop (EV_A_ iow [n]);
		1895
		1896	return got_events;
1206	}	1897	}
1207		1898
1208		1899
1209	=head2 C<ev_embed> - when one backend isn't enough...	1900	=head2 C<ev_embed> - when one backend isn't enough...
1210		1901
…		…
1253	portable one.	1944	portable one.
1254		1945
1255	So when you want to use this feature you will always have to be prepared	1946	So when you want to use this feature you will always have to be prepared
1256	that you cannot get an embeddable loop. The recommended way to get around	1947	that you cannot get an embeddable loop. The recommended way to get around
1257	this is to have a separate variables for your embeddable loop, try to	1948	this is to have a separate variables for your embeddable loop, try to
1258	create it, and if that fails, use the normal loop for everything:	1949	create it, and if that fails, use the normal loop for everything.
		1950
		1951	=head3 Watcher-Specific Functions and Data Members
		1952
		1953	=over 4
		1954
		1955	=item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)
		1956
		1957	=item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)
		1958
		1959	Configures the watcher to embed the given loop, which must be
		1960	embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be
		1961	invoked automatically, otherwise it is the responsibility of the callback
		1962	to invoke it (it will continue to be called until the sweep has been done,
		1963	if you do not want thta, you need to temporarily stop the embed watcher).
		1964
		1965	=item ev_embed_sweep (loop, ev_embed *)
		1966
		1967	Make a single, non-blocking sweep over the embedded loop. This works
		1968	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
		1969	apropriate way for embedded loops.
		1970
		1971	=item struct ev_loop *other [read-only]
		1972
		1973	The embedded event loop.
		1974
		1975	=back
		1976
		1977	=head3 Examples
		1978
		1979	Example: Try to get an embeddable event loop and embed it into the default
		1980	event loop. If that is not possible, use the default loop. The default
		1981	loop is stored in C<loop_hi>, while the mebeddable loop is stored in
		1982	C<loop_lo> (which is C<loop_hi> in the acse no embeddable loop can be
		1983	used).
1259		1984
1260	struct ev_loop *loop_hi = ev_default_init (0);	1985	struct ev_loop *loop_hi = ev_default_init (0);
1261	struct ev_loop *loop_lo = 0;	1986	struct ev_loop *loop_lo = 0;
1262	struct ev_embed embed;	1987	struct ev_embed embed;
1263		1988
…		…
1274	ev_embed_start (loop_hi, &embed);	1999	ev_embed_start (loop_hi, &embed);
1275	}	2000	}
1276	else	2001	else
1277	loop_lo = loop_hi;	2002	loop_lo = loop_hi;
1278		2003
		2004	Example: Check if kqueue is available but not recommended and create
		2005	a kqueue backend for use with sockets (which usually work with any
		2006	kqueue implementation). Store the kqueue/socket-only event loop in
		2007	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).
		2008
		2009	struct ev_loop *loop = ev_default_init (0);
		2010	struct ev_loop *loop_socket = 0;
		2011	struct ev_embed embed;
		2012
		2013	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)
		2014	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))
		2015	{
		2016	ev_embed_init (&embed, 0, loop_socket);
		2017	ev_embed_start (loop, &embed);
		2018	}
		2019
		2020	if (!loop_socket)
		2021	loop_socket = loop;
		2022
		2023	// now use loop_socket for all sockets, and loop for everything else
		2024
		2025
		2026	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
		2027
		2028	Fork watchers are called when a C<fork ()> was detected (usually because
		2029	whoever is a good citizen cared to tell libev about it by calling
		2030	C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the
		2031	event loop blocks next and before C<ev_check> watchers are being called,
		2032	and only in the child after the fork. If whoever good citizen calling
		2033	C<ev_default_fork> cheats and calls it in the wrong process, the fork
		2034	handlers will be invoked, too, of course.
		2035
		2036	=head3 Watcher-Specific Functions and Data Members
		2037
1279	=over 4	2038	=over 4
1280		2039
1281	=item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)	2040	=item ev_fork_init (ev_signal *, callback)
1282		2041
1283	=item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)	2042	Initialises and configures the fork watcher - it has no parameters of any
1284		2043	kind. There is a C<ev_fork_set> macro, but using it is utterly pointless,
1285	Configures the watcher to embed the given loop, which must be	2044	believe me.
1286	embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be
1287	invoked automatically, otherwise it is the responsibility of the callback
1288	to invoke it (it will continue to be called until the sweep has been done,
1289	if you do not want thta, you need to temporarily stop the embed watcher).
1290
1291	=item ev_embed_sweep (loop, ev_embed *)
1292
1293	Make a single, non-blocking sweep over the embedded loop. This works
1294	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
1295	apropriate way for embedded loops.
1296		2045
1297	=back	2046	=back
1298		2047
1299		2048
1300	=head1 OTHER FUNCTIONS	2049	=head1 OTHER FUNCTIONS
…		…
1389		2138
1390	To use it,	2139	To use it,
1391		2140
1392	#include <ev++.h>	2141	#include <ev++.h>
1393		2142
1394	(it is not installed by default). This automatically includes F<ev.h>	2143	This automatically includes F<ev.h> and puts all of its definitions (many
1395	and puts all of its definitions (many of them macros) into the global	2144	of them macros) into the global namespace. All C++ specific things are
1396	namespace. All C++ specific things are put into the C<ev> namespace.	2145	put into the C<ev> namespace. It should support all the same embedding
		2146	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
1397		2147
1398	It should support all the same embedding options as F<ev.h>, most notably	2148	Care has been taken to keep the overhead low. The only data member the C++
1399	C<EV_MULTIPLICITY>.	2149	classes add (compared to plain C-style watchers) is the event loop pointer
		2150	that the watcher is associated with (or no additional members at all if
		2151	you disable C<EV_MULTIPLICITY> when embedding libev).
		2152
		2153	Currently, functions, and static and non-static member functions can be
		2154	used as callbacks. Other types should be easy to add as long as they only
		2155	need one additional pointer for context. If you need support for other
		2156	types of functors please contact the author (preferably after implementing
		2157	it).
1400		2158
1401	Here is a list of things available in the C<ev> namespace:	2159	Here is a list of things available in the C<ev> namespace:
1402		2160
1403	=over 4	2161	=over 4
1404		2162
…		…
1420		2178
1421	All of those classes have these methods:	2179	All of those classes have these methods:
1422		2180
1423	=over 4	2181	=over 4
1424		2182
1425	=item ev::TYPE::TYPE (object *, object::method *)	2183	=item ev::TYPE::TYPE ()
1426		2184
1427	=item ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)	2185	=item ev::TYPE::TYPE (struct ev_loop *)
1428		2186
1429	=item ev::TYPE::~TYPE	2187	=item ev::TYPE::~TYPE
1430		2188
1431	The constructor takes a pointer to an object and a method pointer to	2189	The constructor (optionally) takes an event loop to associate the watcher
1432	the event handler callback to call in this class. The constructor calls	2190	with. If it is omitted, it will use C<EV_DEFAULT>.
1433	C<ev_init> for you, which means you have to call the C<set> method	2191
1434	before starting it. If you do not specify a loop then the constructor	2192	The constructor calls C<ev_init> for you, which means you have to call the
1435	automatically associates the default loop with this watcher.	2193	C<set> method before starting it.
		2194
		2195	It will not set a callback, however: You have to call the templated C<set>
		2196	method to set a callback before you can start the watcher.
		2197
		2198	(The reason why you have to use a method is a limitation in C++ which does
		2199	not allow explicit template arguments for constructors).
1436		2200
1437	The destructor automatically stops the watcher if it is active.	2201	The destructor automatically stops the watcher if it is active.
		2202
		2203	=item w->set<class, &class::method> (object *)
		2204
		2205	This method sets the callback method to call. The method has to have a
		2206	signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as
		2207	first argument and the C<revents> as second. The object must be given as
		2208	parameter and is stored in the C<data> member of the watcher.
		2209
		2210	This method synthesizes efficient thunking code to call your method from
		2211	the C callback that libev requires. If your compiler can inline your
		2212	callback (i.e. it is visible to it at the place of the C<set> call and
		2213	your compiler is good :), then the method will be fully inlined into the
		2214	thunking function, making it as fast as a direct C callback.
		2215
		2216	Example: simple class declaration and watcher initialisation
		2217
		2218	struct myclass
		2219	{
		2220	void io_cb (ev::io &w, int revents) { }
		2221	}
		2222
		2223	myclass obj;
		2224	ev::io iow;
		2225	iow.set <myclass, &myclass::io_cb> (&obj);
		2226
		2227	=item w->set<function> (void *data = 0)
		2228
		2229	Also sets a callback, but uses a static method or plain function as
		2230	callback. The optional C<data> argument will be stored in the watcher's
		2231	C<data> member and is free for you to use.
		2232
		2233	The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>.
		2234
		2235	See the method-C<set> above for more details.
		2236
		2237	Example:
		2238
		2239	static void io_cb (ev::io &w, int revents) { }
		2240	iow.set <io_cb> ();
1438		2241
1439	=item w->set (struct ev_loop *)	2242	=item w->set (struct ev_loop *)
1440		2243
1441	Associates a different C<struct ev_loop> with this watcher. You can only	2244	Associates a different C<struct ev_loop> with this watcher. You can only
1442	do this when the watcher is inactive (and not pending either).	2245	do this when the watcher is inactive (and not pending either).
1443		2246
1444	=item w->set ([args])	2247	=item w->set ([args])
1445		2248
1446	Basically the same as C<ev_TYPE_set>, with the same args. Must be	2249	Basically the same as C<ev_TYPE_set>, with the same args. Must be
1447	called at least once. Unlike the C counterpart, an active watcher gets	2250	called at least once. Unlike the C counterpart, an active watcher gets
1448	automatically stopped and restarted.	2251	automatically stopped and restarted when reconfiguring it with this
		2252	method.
1449		2253
1450	=item w->start ()	2254	=item w->start ()
1451		2255
1452	Starts the watcher. Note that there is no C<loop> argument as the	2256	Starts the watcher. Note that there is no C<loop> argument, as the
1453	constructor already takes the loop.	2257	constructor already stores the event loop.
1454		2258
1455	=item w->stop ()	2259	=item w->stop ()
1456		2260
1457	Stops the watcher if it is active. Again, no C<loop> argument.	2261	Stops the watcher if it is active. Again, no C<loop> argument.
1458		2262
1459	=item w->again () C<ev::timer>, C<ev::periodic> only	2263	=item w->again () (C<ev::timer>, C<ev::periodic> only)
1460		2264
1461	For C<ev::timer> and C<ev::periodic>, this invokes the corresponding	2265	For C<ev::timer> and C<ev::periodic>, this invokes the corresponding
1462	C<ev_TYPE_again> function.	2266	C<ev_TYPE_again> function.
1463		2267
1464	=item w->sweep () C<ev::embed> only	2268	=item w->sweep () (C<ev::embed> only)
1465		2269
1466	Invokes C<ev_embed_sweep>.	2270	Invokes C<ev_embed_sweep>.
		2271
		2272	=item w->update () (C<ev::stat> only)
		2273
		2274	Invokes C<ev_stat_stat>.
1467		2275
1468	=back	2276	=back
1469		2277
1470	=back	2278	=back
1471		2279
…		…
1479		2287
1480	myclass ();	2288	myclass ();
1481	}	2289	}
1482		2290
1483	myclass::myclass (int fd)	2291	myclass::myclass (int fd)
1484	: io (this, &myclass::io_cb),
1485	idle (this, &myclass::idle_cb)
1486	{	2292	{
		2293	io .set <myclass, &myclass::io_cb > (this);
		2294	idle.set <myclass, &myclass::idle_cb> (this);
		2295
1487	io.start (fd, ev::READ);	2296	io.start (fd, ev::READ);
1488	}	2297	}
		2298
		2299
		2300	=head1 MACRO MAGIC
		2301
		2302	Libev can be compiled with a variety of options, the most fundamantal
		2303	of which is C<EV_MULTIPLICITY>. This option determines whether (most)
		2304	functions and callbacks have an initial C<struct ev_loop *> argument.
		2305
		2306	To make it easier to write programs that cope with either variant, the
		2307	following macros are defined:
		2308
		2309	=over 4
		2310
		2311	=item C<EV_A>, C<EV_A_>
		2312
		2313	This provides the loop I<argument> for functions, if one is required ("ev
		2314	loop argument"). The C<EV_A> form is used when this is the sole argument,
		2315	C<EV_A_> is used when other arguments are following. Example:
		2316
		2317	ev_unref (EV_A);
		2318	ev_timer_add (EV_A_ watcher);
		2319	ev_loop (EV_A_ 0);
		2320
		2321	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
		2322	which is often provided by the following macro.
		2323
		2324	=item C<EV_P>, C<EV_P_>
		2325
		2326	This provides the loop I<parameter> for functions, if one is required ("ev
		2327	loop parameter"). The C<EV_P> form is used when this is the sole parameter,
		2328	C<EV_P_> is used when other parameters are following. Example:
		2329
		2330	// this is how ev_unref is being declared
		2331	static void ev_unref (EV_P);
		2332
		2333	// this is how you can declare your typical callback
		2334	static void cb (EV_P_ ev_timer *w, int revents)
		2335
		2336	It declares a parameter C<loop> of type C<struct ev_loop *>, quite
		2337	suitable for use with C<EV_A>.
		2338
		2339	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
		2340
		2341	Similar to the other two macros, this gives you the value of the default
		2342	loop, if multiple loops are supported ("ev loop default").
		2343
		2344	=back
		2345
		2346	Example: Declare and initialise a check watcher, utilising the above
		2347	macros so it will work regardless of whether multiple loops are supported
		2348	or not.
		2349
		2350	static void
		2351	check_cb (EV_P_ ev_timer *w, int revents)
		2352	{
		2353	ev_check_stop (EV_A_ w);
		2354	}
		2355
		2356	ev_check check;
		2357	ev_check_init (&check, check_cb);
		2358	ev_check_start (EV_DEFAULT_ &check);
		2359	ev_loop (EV_DEFAULT_ 0);
1489		2360
1490	=head1 EMBEDDING	2361	=head1 EMBEDDING
1491		2362
1492	Libev can (and often is) directly embedded into host	2363	Libev can (and often is) directly embedded into host
1493	applications. Examples of applications that embed it include the Deliantra	2364	applications. Examples of applications that embed it include the Deliantra
1494	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)	2365	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
1495	and rxvt-unicode.	2366	and rxvt-unicode.
1496		2367
1497	The goal is to enable you to just copy the neecssary files into your	2368	The goal is to enable you to just copy the necessary files into your
1498	source directory without having to change even a single line in them, so	2369	source directory without having to change even a single line in them, so
1499	you can easily upgrade by simply copying (or having a checked-out copy of	2370	you can easily upgrade by simply copying (or having a checked-out copy of
1500	libev somewhere in your source tree).	2371	libev somewhere in your source tree).
1501		2372
1502	=head2 FILESETS	2373	=head2 FILESETS
…		…
1533	ev_vars.h	2404	ev_vars.h
1534	ev_wrap.h	2405	ev_wrap.h
1535		2406
1536	ev_win32.c required on win32 platforms only	2407	ev_win32.c required on win32 platforms only
1537		2408
1538	ev_select.c only when select backend is enabled (which is by default)	2409	ev_select.c only when select backend is enabled (which is enabled by default)
1539	ev_poll.c only when poll backend is enabled (disabled by default)	2410	ev_poll.c only when poll backend is enabled (disabled by default)
1540	ev_epoll.c only when the epoll backend is enabled (disabled by default)	2411	ev_epoll.c only when the epoll backend is enabled (disabled by default)
1541	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	2412	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
1542	ev_port.c only when the solaris port backend is enabled (disabled by default)	2413	ev_port.c only when the solaris port backend is enabled (disabled by default)
1543		2414
…		…
1592		2463
1593	If defined to be C<1>, libev will try to detect the availability of the	2464	If defined to be C<1>, libev will try to detect the availability of the
1594	monotonic clock option at both compiletime and runtime. Otherwise no use	2465	monotonic clock option at both compiletime and runtime. Otherwise no use
1595	of the monotonic clock option will be attempted. If you enable this, you	2466	of the monotonic clock option will be attempted. If you enable this, you
1596	usually have to link against librt or something similar. Enabling it when	2467	usually have to link against librt or something similar. Enabling it when
1597	the functionality isn't available is safe, though, althoguh you have	2468	the functionality isn't available is safe, though, although you have
1598	to make sure you link against any libraries where the C<clock_gettime>	2469	to make sure you link against any libraries where the C<clock_gettime>
1599	function is hiding in (often F<-lrt>).	2470	function is hiding in (often F<-lrt>).
1600		2471
1601	=item EV_USE_REALTIME	2472	=item EV_USE_REALTIME
1602		2473
1603	If defined to be C<1>, libev will try to detect the availability of the	2474	If defined to be C<1>, libev will try to detect the availability of the
1604	realtime clock option at compiletime (and assume its availability at	2475	realtime clock option at compiletime (and assume its availability at
1605	runtime if successful). Otherwise no use of the realtime clock option will	2476	runtime if successful). Otherwise no use of the realtime clock option will
1606	be attempted. This effectively replaces C<gettimeofday> by C<clock_get	2477	be attempted. This effectively replaces C<gettimeofday> by C<clock_get
1607	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries	2478	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the
1608	in the description of C<EV_USE_MONOTONIC>, though.	2479	note about libraries in the description of C<EV_USE_MONOTONIC>, though.
		2480
		2481	=item EV_USE_NANOSLEEP
		2482
		2483	If defined to be C<1>, libev will assume that C<nanosleep ()> is available
		2484	and will use it for delays. Otherwise it will use C<select ()>.
1609		2485
1610	=item EV_USE_SELECT	2486	=item EV_USE_SELECT
1611		2487
1612	If undefined or defined to be C<1>, libev will compile in support for the	2488	If undefined or defined to be C<1>, libev will compile in support for the
1613	C<select>(2) backend. No attempt at autodetection will be done: if no	2489	C<select>(2) backend. No attempt at autodetection will be done: if no
…		…
1631	wants osf handles on win32 (this is the case when the select to	2507	wants osf handles on win32 (this is the case when the select to
1632	be used is the winsock select). This means that it will call	2508	be used is the winsock select). This means that it will call
1633	C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise,	2509	C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise,
1634	it is assumed that all these functions actually work on fds, even	2510	it is assumed that all these functions actually work on fds, even
1635	on win32. Should not be defined on non-win32 platforms.	2511	on win32. Should not be defined on non-win32 platforms.
		2512
		2513	=item EV_FD_TO_WIN32_HANDLE
		2514
		2515	If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map
		2516	file descriptors to socket handles. When not defining this symbol (the
		2517	default), then libev will call C<_get_osfhandle>, which is usually
		2518	correct. In some cases, programs use their own file descriptor management,
		2519	in which case they can provide this function to map fds to socket handles.
1636		2520
1637	=item EV_USE_POLL	2521	=item EV_USE_POLL
1638		2522
1639	If defined to be C<1>, libev will compile in support for the C<poll>(2)	2523	If defined to be C<1>, libev will compile in support for the C<poll>(2)
1640	backend. Otherwise it will be enabled on non-win32 platforms. It	2524	backend. Otherwise it will be enabled on non-win32 platforms. It
…		…
1668		2552
1669	=item EV_USE_DEVPOLL	2553	=item EV_USE_DEVPOLL
1670		2554
1671	reserved for future expansion, works like the USE symbols above.	2555	reserved for future expansion, works like the USE symbols above.
1672		2556
		2557	=item EV_USE_INOTIFY
		2558
		2559	If defined to be C<1>, libev will compile in support for the Linux inotify
		2560	interface to speed up C<ev_stat> watchers. Its actual availability will
		2561	be detected at runtime.
		2562
1673	=item EV_H	2563	=item EV_H
1674		2564
1675	The name of the F<ev.h> header file used to include it. The default if	2565	The name of the F<ev.h> header file used to include it. The default if
1676	undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This	2566	undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be
1677	can be used to virtually rename the F<ev.h> header file in case of conflicts.	2567	used to virtually rename the F<ev.h> header file in case of conflicts.
1678		2568
1679	=item EV_CONFIG_H	2569	=item EV_CONFIG_H
1680		2570
1681	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override	2571	If C<EV_STANDALONE> isn't C<1>, this variable can be used to override
1682	F<ev.c>'s idea of where to find the F<config.h> file, similarly to	2572	F<ev.c>'s idea of where to find the F<config.h> file, similarly to
1683	C<EV_H>, above.	2573	C<EV_H>, above.
1684		2574
1685	=item EV_EVENT_H	2575	=item EV_EVENT_H
1686		2576
1687	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea	2577	Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea
1688	of how the F<event.h> header can be found.	2578	of how the F<event.h> header can be found, the default is C<"event.h">.
1689		2579
1690	=item EV_PROTOTYPES	2580	=item EV_PROTOTYPES
1691		2581
1692	If defined to be C<0>, then F<ev.h> will not define any function	2582	If defined to be C<0>, then F<ev.h> will not define any function
1693	prototypes, but still define all the structs and other symbols. This is	2583	prototypes, but still define all the structs and other symbols. This is
…		…
1700	will have the C<struct ev_loop *> as first argument, and you can create	2590	will have the C<struct ev_loop *> as first argument, and you can create
1701	additional independent event loops. Otherwise there will be no support	2591	additional independent event loops. Otherwise there will be no support
1702	for multiple event loops and there is no first event loop pointer	2592	for multiple event loops and there is no first event loop pointer
1703	argument. Instead, all functions act on the single default loop.	2593	argument. Instead, all functions act on the single default loop.
1704		2594
		2595	=item EV_MINPRI
		2596
		2597	=item EV_MAXPRI
		2598
		2599	The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to
		2600	C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can
		2601	provide for more priorities by overriding those symbols (usually defined
		2602	to be C<-2> and C<2>, respectively).
		2603
		2604	When doing priority-based operations, libev usually has to linearly search
		2605	all the priorities, so having many of them (hundreds) uses a lot of space
		2606	and time, so using the defaults of five priorities (-2 .. +2) is usually
		2607	fine.
		2608
		2609	If your embedding app does not need any priorities, defining these both to
		2610	C<0> will save some memory and cpu.
		2611
1705	=item EV_PERIODICS	2612	=item EV_PERIODIC_ENABLE
1706		2613
1707	If undefined or defined to be C<1>, then periodic timers are supported,	2614	If undefined or defined to be C<1>, then periodic timers are supported. If
1708	otherwise not. This saves a few kb of code.	2615	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2616	code.
		2617
		2618	=item EV_IDLE_ENABLE
		2619
		2620	If undefined or defined to be C<1>, then idle watchers are supported. If
		2621	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2622	code.
		2623
		2624	=item EV_EMBED_ENABLE
		2625
		2626	If undefined or defined to be C<1>, then embed watchers are supported. If
		2627	defined to be C<0>, then they are not.
		2628
		2629	=item EV_STAT_ENABLE
		2630
		2631	If undefined or defined to be C<1>, then stat watchers are supported. If
		2632	defined to be C<0>, then they are not.
		2633
		2634	=item EV_FORK_ENABLE
		2635
		2636	If undefined or defined to be C<1>, then fork watchers are supported. If
		2637	defined to be C<0>, then they are not.
		2638
		2639	=item EV_MINIMAL
		2640
		2641	If you need to shave off some kilobytes of code at the expense of some
		2642	speed, define this symbol to C<1>. Currently only used for gcc to override
		2643	some inlining decisions, saves roughly 30% codesize of amd64.
		2644
		2645	=item EV_PID_HASHSIZE
		2646
		2647	C<ev_child> watchers use a small hash table to distribute workload by
		2648	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
		2649	than enough. If you need to manage thousands of children you might want to
		2650	increase this value (I<must> be a power of two).
		2651
		2652	=item EV_INOTIFY_HASHSIZE
		2653
		2654	C<ev_stat> watchers use a small hash table to distribute workload by
		2655	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
		2656	usually more than enough. If you need to manage thousands of C<ev_stat>
		2657	watchers you might want to increase this value (I<must> be a power of
		2658	two).
1709		2659
1710	=item EV_COMMON	2660	=item EV_COMMON
1711		2661
1712	By default, all watchers have a C<void *data> member. By redefining	2662	By default, all watchers have a C<void *data> member. By redefining
1713	this macro to a something else you can include more and other types of	2663	this macro to a something else you can include more and other types of
…		…
1726		2676
1727	=item ev_set_cb (ev, cb)	2677	=item ev_set_cb (ev, cb)
1728		2678
1729	Can be used to change the callback member declaration in each watcher,	2679	Can be used to change the callback member declaration in each watcher,
1730	and the way callbacks are invoked and set. Must expand to a struct member	2680	and the way callbacks are invoked and set. Must expand to a struct member
1731	definition and a statement, respectively. See the F<ev.v> header file for	2681	definition and a statement, respectively. See the F<ev.h> header file for
1732	their default definitions. One possible use for overriding these is to	2682	their default definitions. One possible use for overriding these is to
1733	avoid the C<struct ev_loop *> as first argument in all cases, or to use	2683	avoid the C<struct ev_loop *> as first argument in all cases, or to use
1734	method calls instead of plain function calls in C++.	2684	method calls instead of plain function calls in C++.
		2685
		2686	=head2 EXPORTED API SYMBOLS
		2687
		2688	If you need to re-export the API (e.g. via a dll) and you need a list of
		2689	exported symbols, you can use the provided F<Symbol.*> files which list
		2690	all public symbols, one per line:
		2691
		2692	Symbols.ev for libev proper
		2693	Symbols.event for the libevent emulation
		2694
		2695	This can also be used to rename all public symbols to avoid clashes with
		2696	multiple versions of libev linked together (which is obviously bad in
		2697	itself, but sometimes it is inconvinient to avoid this).
		2698
		2699	A sed command like this will create wrapper C<#define>'s that you need to
		2700	include before including F<ev.h>:
		2701
		2702	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h
		2703
		2704	This would create a file F<wrap.h> which essentially looks like this:
		2705
		2706	#define ev_backend myprefix_ev_backend
		2707	#define ev_check_start myprefix_ev_check_start
		2708	#define ev_check_stop myprefix_ev_check_stop
		2709	...
1735		2710
1736	=head2 EXAMPLES	2711	=head2 EXAMPLES
1737		2712
1738	For a real-world example of a program the includes libev	2713	For a real-world example of a program the includes libev
1739	verbatim, you can have a look at the EV perl module	2714	verbatim, you can have a look at the EV perl module
…		…
1742	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file	2717	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file
1743	will be compiled. It is pretty complex because it provides its own header	2718	will be compiled. It is pretty complex because it provides its own header
1744	file.	2719	file.
1745		2720
1746	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	2721	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
1747	that everybody includes and which overrides some autoconf choices:	2722	that everybody includes and which overrides some configure choices:
1748		2723
		2724	#define EV_MINIMAL 1
1749	#define EV_USE_POLL 0	2725	#define EV_USE_POLL 0
1750	#define EV_MULTIPLICITY 0	2726	#define EV_MULTIPLICITY 0
1751	#define EV_PERIODICS 0	2727	#define EV_PERIODIC_ENABLE 0
		2728	#define EV_STAT_ENABLE 0
		2729	#define EV_FORK_ENABLE 0
1752	#define EV_CONFIG_H <config.h>	2730	#define EV_CONFIG_H <config.h>
		2731	#define EV_MINPRI 0
		2732	#define EV_MAXPRI 0
1753		2733
1754	#include "ev++.h"	2734	#include "ev++.h"
1755		2735
1756	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	2736	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
1757		2737
…		…
1763		2743
1764	In this section the complexities of (many of) the algorithms used inside	2744	In this section the complexities of (many of) the algorithms used inside
1765	libev will be explained. For complexity discussions about backends see the	2745	libev will be explained. For complexity discussions about backends see the
1766	documentation for C<ev_default_init>.	2746	documentation for C<ev_default_init>.
1767		2747
		2748	All of the following are about amortised time: If an array needs to be
		2749	extended, libev needs to realloc and move the whole array, but this
		2750	happens asymptotically never with higher number of elements, so O(1) might
		2751	mean it might do a lengthy realloc operation in rare cases, but on average
		2752	it is much faster and asymptotically approaches constant time.
		2753
1768	=over 4	2754	=over 4
1769		2755
1770	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)	2756	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
1771		2757
		2758	This means that, when you have a watcher that triggers in one hour and
		2759	there are 100 watchers that would trigger before that then inserting will
		2760	have to skip roughly seven (C<ld 100>) of these watchers.
		2761
1772	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)	2762	=item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers)
		2763
		2764	That means that changing a timer costs less than removing/adding them
		2765	as only the relative motion in the event queue has to be paid for.
1773		2766
1774	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2767	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
1775		2768
		2769	These just add the watcher into an array or at the head of a list.
		2770
1776	=item Stopping check/prepare/idle watchers: O(1)	2771	=item Stopping check/prepare/idle watchers: O(1)
1777		2772
1778	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))	2773	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
1779		2774
		2775	These watchers are stored in lists then need to be walked to find the
		2776	correct watcher to remove. The lists are usually short (you don't usually
		2777	have many watchers waiting for the same fd or signal).
		2778
1780	=item Finding the next timer per loop iteration: O(1)	2779	=item Finding the next timer in each loop iteration: O(1)
		2780
		2781	By virtue of using a binary heap, the next timer is always found at the
		2782	beginning of the storage array.
1781		2783
1782	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	2784	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
1783		2785
1784	=item Activating one watcher: O(1)	2786	A change means an I/O watcher gets started or stopped, which requires
		2787	libev to recalculate its status (and possibly tell the kernel, depending
		2788	on backend and wether C<ev_io_set> was used).
		2789
		2790	=item Activating one watcher (putting it into the pending state): O(1)
		2791
		2792	=item Priority handling: O(number_of_priorities)
		2793
		2794	Priorities are implemented by allocating some space for each
		2795	priority. When doing priority-based operations, libev usually has to
		2796	linearly search all the priorities, but starting/stopping and activating
		2797	watchers becomes O(1) w.r.t. prioritiy handling.
1785		2798
1786	=back	2799	=back
1787		2800
1788		2801
		2802	=head1 Win32 platform limitations and workarounds
		2803
		2804	Win32 doesn't support any of the standards (e.g. POSIX) that libev
		2805	requires, and its I/O model is fundamentally incompatible with the POSIX
		2806	model. Libev still offers limited functionality on this platform in
		2807	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
		2808	descriptors. This only applies when using Win32 natively, not when using
		2809	e.g. cygwin.
		2810
		2811	There is no supported compilation method available on windows except
		2812	embedding it into other applications.
		2813
		2814	Due to the many, low, and arbitrary limits on the win32 platform and the
		2815	abysmal performance of winsockets, using a large number of sockets is not
		2816	recommended (and not reasonable). If your program needs to use more than
		2817	a hundred or so sockets, then likely it needs to use a totally different
		2818	implementation for windows, as libev offers the POSIX model, which cannot
		2819	be implemented efficiently on windows (microsoft monopoly games).
		2820
		2821	=over 4
		2822
		2823	=item The winsocket select function
		2824
		2825	The winsocket C<select> function doesn't follow POSIX in that it requires
		2826	socket I<handles> and not socket I<file descriptors>. This makes select
		2827	very inefficient, and also requires a mapping from file descriptors
		2828	to socket handles. See the discussion of the C<EV_SELECT_USE_FD_SET>,
		2829	C<EV_SELECT_IS_WINSOCKET> and C<EV_FD_TO_WIN32_HANDLE> preprocessor
		2830	symbols for more info.
		2831
		2832	The configuration for a "naked" win32 using the microsoft runtime
		2833	libraries and raw winsocket select is:
		2834
		2835	#define EV_USE_SELECT 1
		2836	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
		2837
		2838	Note that winsockets handling of fd sets is O(n), so you can easily get a
		2839	complexity in the O(n²) range when using win32.
		2840
		2841	=item Limited number of file descriptors
		2842
		2843	Windows has numerous arbitrary (and low) limits on things. Early versions
		2844	of winsocket's select only supported waiting for a max. of C<64> handles
		2845	(probably owning to the fact that all windows kernels can only wait for
		2846	C<64> things at the same time internally; microsoft recommends spawning a
		2847	chain of threads and wait for 63 handles and the previous thread in each).
		2848
		2849	Newer versions support more handles, but you need to define C<FD_SETSIZE>
		2850	to some high number (e.g. C<2048>) before compiling the winsocket select
		2851	call (which might be in libev or elsewhere, for example, perl does its own
		2852	select emulation on windows).
		2853
		2854	Another limit is the number of file descriptors in the microsoft runtime
		2855	libraries, which by default is C<64> (there must be a hidden I<64> fetish
		2856	or something like this inside microsoft). You can increase this by calling
		2857	C<_setmaxstdio>, which can increase this limit to C<2048> (another
		2858	arbitrary limit), but is broken in many versions of the microsoft runtime
		2859	libraries.
		2860
		2861	This might get you to about C<512> or C<2048> sockets (depending on
		2862	windows version and/or the phase of the moon). To get more, you need to
		2863	wrap all I/O functions and provide your own fd management, but the cost of
		2864	calling select (O(n²)) will likely make this unworkable.
		2865
		2866	=back
		2867
		2868
1789	=head1 AUTHOR	2869	=head1 AUTHOR
1790		2870
1791	Marc Lehmann <libev@schmorp.de>.	2871	Marc Lehmann <libev@schmorp.de>.
1792		2872

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