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Revision 1.138 by root, Mon Mar 31 01:14:12 2008 UTC vs.
Revision 1.168 by root, Mon Jun 9 14:31:36 2008 UTC

…		…
2		2
3	libev - a high performance full-featured event loop written in C	3	libev - a high performance full-featured event loop written in C
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	#include <ev.h>	7	#include <ev.h>
8		8
9	=head2 EXAMPLE PROGRAM	9	=head2 EXAMPLE PROGRAM
10		10
11	// a single header file is required	11	// a single header file is required
12	#include <ev.h>	12	#include <ev.h>
13		13
14	// every watcher type has its own typedef'd struct	14	// every watcher type has its own typedef'd struct
15	// with the name ev_<type>	15	// with the name ev_<type>
16	ev_io stdin_watcher;	16	ev_io stdin_watcher;
17	ev_timer timeout_watcher;	17	ev_timer timeout_watcher;
18		18
19	// all watcher callbacks have a similar signature	19	// all watcher callbacks have a similar signature
20	// this callback is called when data is readable on stdin	20	// this callback is called when data is readable on stdin
21	static void	21	static void
22	stdin_cb (EV_P_ struct ev_io *w, int revents)	22	stdin_cb (EV_P_ struct ev_io *w, int revents)
23	{	23	{
24	puts ("stdin ready");	24	puts ("stdin ready");
25	// for one-shot events, one must manually stop the watcher	25	// for one-shot events, one must manually stop the watcher
26	// with its corresponding stop function.	26	// with its corresponding stop function.
27	ev_io_stop (EV_A_ w);	27	ev_io_stop (EV_A_ w);
28		28
29	// this causes all nested ev_loop's to stop iterating	29	// this causes all nested ev_loop's to stop iterating
30	ev_unloop (EV_A_ EVUNLOOP_ALL);	30	ev_unloop (EV_A_ EVUNLOOP_ALL);
31	}	31	}
32		32
33	// another callback, this time for a time-out	33	// another callback, this time for a time-out
34	static void	34	static void
35	timeout_cb (EV_P_ struct ev_timer *w, int revents)	35	timeout_cb (EV_P_ struct ev_timer *w, int revents)
36	{	36	{
37	puts ("timeout");	37	puts ("timeout");
38	// this causes the innermost ev_loop to stop iterating	38	// this causes the innermost ev_loop to stop iterating
39	ev_unloop (EV_A_ EVUNLOOP_ONE);	39	ev_unloop (EV_A_ EVUNLOOP_ONE);
40	}	40	}
41		41
42	int	42	int
43	main (void)	43	main (void)
44	{	44	{
45	// use the default event loop unless you have special needs	45	// use the default event loop unless you have special needs
46	struct ev_loop *loop = ev_default_loop (0);	46	struct ev_loop *loop = ev_default_loop (0);
47		47
48	// initialise an io watcher, then start it	48	// initialise an io watcher, then start it
49	// this one will watch for stdin to become readable	49	// this one will watch for stdin to become readable
50	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);	50	ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);
51	ev_io_start (loop, &stdin_watcher);	51	ev_io_start (loop, &stdin_watcher);
52		52
53	// initialise a timer watcher, then start it	53	// initialise a timer watcher, then start it
54	// simple non-repeating 5.5 second timeout	54	// simple non-repeating 5.5 second timeout
55	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);	55	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
56	ev_timer_start (loop, &timeout_watcher);	56	ev_timer_start (loop, &timeout_watcher);
57		57
58	// now wait for events to arrive	58	// now wait for events to arrive
59	ev_loop (loop, 0);	59	ev_loop (loop, 0);
60		60
61	// unloop was called, so exit	61	// unloop was called, so exit
62	return 0;	62	return 0;
63	}	63	}
64		64
65	=head1 DESCRIPTION	65	=head1 DESCRIPTION
66		66
67	The newest version of this document is also available as an html-formatted	67	The newest version of this document is also available as an html-formatted
68	web page you might find easier to navigate when reading it for the first	68	web page you might find easier to navigate when reading it for the first
69	time: L<http://cvs.schmorp.de/libev/ev.html>.	69	time: L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>.
70		70
71	Libev is an event loop: you register interest in certain events (such as a	71	Libev is an event loop: you register interest in certain events (such as a
72	file descriptor being readable or a timeout occurring), and it will manage	72	file descriptor being readable or a timeout occurring), and it will manage
73	these event sources and provide your program with events.	73	these event sources and provide your program with events.
74		74
…		…
113	Libev represents time as a single floating point number, representing the	113	Libev represents time as a single floating point number, representing the
114	(fractional) number of seconds since the (POSIX) epoch (somewhere near	114	(fractional) number of seconds since the (POSIX) epoch (somewhere near
115	the beginning of 1970, details are complicated, don't ask). This type is	115	the beginning of 1970, details are complicated, don't ask). This type is
116	called C<ev_tstamp>, which is what you should use too. It usually aliases	116	called C<ev_tstamp>, which is what you should use too. It usually aliases
117	to the C<double> type in C, and when you need to do any calculations on	117	to the C<double> type in C, and when you need to do any calculations on
118	it, you should treat it as some floatingpoint value. Unlike the name	118	it, you should treat it as some floating point value. Unlike the name
119	component C<stamp> might indicate, it is also used for time differences	119	component C<stamp> might indicate, it is also used for time differences
120	throughout libev.	120	throughout libev.
		121
		122	=head1 ERROR HANDLING
		123
		124	Libev knows three classes of errors: operating system errors, usage errors
		125	and internal errors (bugs).
		126
		127	When libev catches an operating system error it cannot handle (for example
		128	a system call indicating a condition libev cannot fix), it calls the callback
		129	set via C<ev_set_syserr_cb>, which is supposed to fix the problem or
		130	abort. The default is to print a diagnostic message and to call C<abort
		131	()>.
		132
		133	When libev detects a usage error such as a negative timer interval, then
		134	it will print a diagnostic message and abort (via the C<assert> mechanism,
		135	so C<NDEBUG> will disable this checking): these are programming errors in
		136	the libev caller and need to be fixed there.
		137
		138	Libev also has a few internal error-checking C<assert>ions, and also has
		139	extensive consistency checking code. These do not trigger under normal
		140	circumstances, as they indicate either a bug in libev or worse.
		141
121		142
122	=head1 GLOBAL FUNCTIONS	143	=head1 GLOBAL FUNCTIONS
123		144
124	These functions can be called anytime, even before initialising the	145	These functions can be called anytime, even before initialising the
125	library in any way.	146	library in any way.
…		…
134		155
135	=item ev_sleep (ev_tstamp interval)	156	=item ev_sleep (ev_tstamp interval)
136		157
137	Sleep for the given interval: The current thread will be blocked until	158	Sleep for the given interval: The current thread will be blocked until
138	either it is interrupted or the given time interval has passed. Basically	159	either it is interrupted or the given time interval has passed. Basically
139	this is a subsecond-resolution C<sleep ()>.	160	this is a sub-second-resolution C<sleep ()>.
140		161
141	=item int ev_version_major ()	162	=item int ev_version_major ()
142		163
143	=item int ev_version_minor ()	164	=item int ev_version_minor ()
144		165
…		…
157	not a problem.	178	not a problem.
158		179
159	Example: Make sure we haven't accidentally been linked against the wrong	180	Example: Make sure we haven't accidentally been linked against the wrong
160	version.	181	version.
161		182
162	assert (("libev version mismatch",	183	assert (("libev version mismatch",
163	ev_version_major () == EV_VERSION_MAJOR	184	ev_version_major () == EV_VERSION_MAJOR
164	&& ev_version_minor () >= EV_VERSION_MINOR));	185	&& ev_version_minor () >= EV_VERSION_MINOR));
165		186
166	=item unsigned int ev_supported_backends ()	187	=item unsigned int ev_supported_backends ()
167		188
168	Return the set of all backends (i.e. their corresponding C<EV_BACKEND_*>	189	Return the set of all backends (i.e. their corresponding C<EV_BACKEND_*>
169	value) compiled into this binary of libev (independent of their	190	value) compiled into this binary of libev (independent of their
…		…
171	a description of the set values.	192	a description of the set values.
172		193
173	Example: make sure we have the epoll method, because yeah this is cool and	194	Example: make sure we have the epoll method, because yeah this is cool and
174	a must have and can we have a torrent of it please!!!11	195	a must have and can we have a torrent of it please!!!11
175		196
176	assert (("sorry, no epoll, no sex",	197	assert (("sorry, no epoll, no sex",
177	ev_supported_backends () & EVBACKEND_EPOLL));	198	ev_supported_backends () & EVBACKEND_EPOLL));
178		199
179	=item unsigned int ev_recommended_backends ()	200	=item unsigned int ev_recommended_backends ()
180		201
181	Return the set of all backends compiled into this binary of libev and also	202	Return the set of all backends compiled into this binary of libev and also
182	recommended for this platform. This set is often smaller than the one	203	recommended for this platform. This set is often smaller than the one
183	returned by C<ev_supported_backends>, as for example kqueue is broken on	204	returned by C<ev_supported_backends>, as for example kqueue is broken on
184	most BSDs and will not be autodetected unless you explicitly request it	205	most BSDs and will not be auto-detected unless you explicitly request it
185	(assuming you know what you are doing). This is the set of backends that	206	(assuming you know what you are doing). This is the set of backends that
186	libev will probe for if you specify no backends explicitly.	207	libev will probe for if you specify no backends explicitly.
187		208
188	=item unsigned int ev_embeddable_backends ()	209	=item unsigned int ev_embeddable_backends ()
189		210
…		…
196	See the description of C<ev_embed> watchers for more info.	217	See the description of C<ev_embed> watchers for more info.
197		218
198	=item ev_set_allocator (void *(*cb)(void *ptr, long size))	219	=item ev_set_allocator (void *(*cb)(void *ptr, long size))
199		220
200	Sets the allocation function to use (the prototype is similar - the	221	Sets the allocation function to use (the prototype is similar - the
201	semantics is identical - to the realloc C function). It is used to	222	semantics are identical to the C<realloc> C89/SuS/POSIX function). It is
202	allocate and free memory (no surprises here). If it returns zero when	223	used to allocate and free memory (no surprises here). If it returns zero
203	memory needs to be allocated, the library might abort or take some	224	when memory needs to be allocated (C<size != 0>), the library might abort
204	potentially destructive action. The default is your system realloc	225	or take some potentially destructive action.
205	function.	226
		227	Since some systems (at least OpenBSD and Darwin) fail to implement
		228	correct C<realloc> semantics, libev will use a wrapper around the system
		229	C<realloc> and C<free> functions by default.
206		230
207	You could override this function in high-availability programs to, say,	231	You could override this function in high-availability programs to, say,
208	free some memory if it cannot allocate memory, to use a special allocator,	232	free some memory if it cannot allocate memory, to use a special allocator,
209	or even to sleep a while and retry until some memory is available.	233	or even to sleep a while and retry until some memory is available.
210		234
211	Example: Replace the libev allocator with one that waits a bit and then	235	Example: Replace the libev allocator with one that waits a bit and then
212	retries).	236	retries (example requires a standards-compliant C<realloc>).
213		237
214	static void *	238	static void *
215	persistent_realloc (void *ptr, size_t size)	239	persistent_realloc (void *ptr, size_t size)
216	{	240	{
217	for (;;)	241	for (;;)
…		…
228	...	252	...
229	ev_set_allocator (persistent_realloc);	253	ev_set_allocator (persistent_realloc);
230		254
231	=item ev_set_syserr_cb (void (*cb)(const char *msg));	255	=item ev_set_syserr_cb (void (*cb)(const char *msg));
232		256
233	Set the callback function to call on a retryable syscall error (such	257	Set the callback function to call on a retryable system call error (such
234	as failed select, poll, epoll_wait). The message is a printable string	258	as failed select, poll, epoll_wait). The message is a printable string
235	indicating the system call or subsystem causing the problem. If this	259	indicating the system call or subsystem causing the problem. If this
236	callback is set, then libev will expect it to remedy the sitution, no	260	callback is set, then libev will expect it to remedy the situation, no
237	matter what, when it returns. That is, libev will generally retry the	261	matter what, when it returns. That is, libev will generally retry the
238	requested operation, or, if the condition doesn't go away, do bad stuff	262	requested operation, or, if the condition doesn't go away, do bad stuff
239	(such as abort).	263	(such as abort).
240		264
241	Example: This is basically the same thing that libev does internally, too.	265	Example: This is basically the same thing that libev does internally, too.
…		…
255	=head1 FUNCTIONS CONTROLLING THE EVENT LOOP	279	=head1 FUNCTIONS CONTROLLING THE EVENT LOOP
256		280
257	An event loop is described by a C<struct ev_loop *>. The library knows two	281	An event loop is described by a C<struct ev_loop *>. The library knows two
258	types of such loops, the I<default> loop, which supports signals and child	282	types of such loops, the I<default> loop, which supports signals and child
259	events, and dynamically created loops which do not.	283	events, and dynamically created loops which do not.
260
261	If you use threads, a common model is to run the default event loop
262	in your main thread (or in a separate thread) and for each thread you
263	create, you also create another event loop. Libev itself does no locking
264	whatsoever, so if you mix calls to the same event loop in different
265	threads, make sure you lock (this is usually a bad idea, though, even if
266	done correctly, because it's hideous and inefficient).
267		284
268	=over 4	285	=over 4
269		286
270	=item struct ev_loop *ev_default_loop (unsigned int flags)	287	=item struct ev_loop *ev_default_loop (unsigned int flags)
271		288
…		…
275	flags. If that is troubling you, check C<ev_backend ()> afterwards).	292	flags. If that is troubling you, check C<ev_backend ()> afterwards).
276		293
277	If you don't know what event loop to use, use the one returned from this	294	If you don't know what event loop to use, use the one returned from this
278	function.	295	function.
279		296
		297	Note that this function is I<not> thread-safe, so if you want to use it
		298	from multiple threads, you have to lock (note also that this is unlikely,
		299	as loops cannot bes hared easily between threads anyway).
		300
280	The default loop is the only loop that can handle C<ev_signal> and	301	The default loop is the only loop that can handle C<ev_signal> and
281	C<ev_child> watchers, and to do this, it always registers a handler	302	C<ev_child> watchers, and to do this, it always registers a handler
282	for C<SIGCHLD>. If this is a problem for your app you can either	303	for C<SIGCHLD>. If this is a problem for your application you can either
283	create a dynamic loop with C<ev_loop_new> that doesn't do that, or you	304	create a dynamic loop with C<ev_loop_new> that doesn't do that, or you
284	can simply overwrite the C<SIGCHLD> signal handler I<after> calling	305	can simply overwrite the C<SIGCHLD> signal handler I<after> calling
285	C<ev_default_init>.	306	C<ev_default_init>.
286		307
287	The flags argument can be used to specify special behaviour or specific	308	The flags argument can be used to specify special behaviour or specific
…		…
296	The default flags value. Use this if you have no clue (it's the right	317	The default flags value. Use this if you have no clue (it's the right
297	thing, believe me).	318	thing, believe me).
298		319
299	=item C<EVFLAG_NOENV>	320	=item C<EVFLAG_NOENV>
300		321
301	If this flag bit is ored into the flag value (or the program runs setuid	322	If this flag bit is or'ed into the flag value (or the program runs setuid
302	or setgid) then libev will I<not> look at the environment variable	323	or setgid) then libev will I<not> look at the environment variable
303	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	324	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
304	override the flags completely if it is found in the environment. This is	325	override the flags completely if it is found in the environment. This is
305	useful to try out specific backends to test their performance, or to work	326	useful to try out specific backends to test their performance, or to work
306	around bugs.	327	around bugs.
…		…
313		334
314	This works by calling C<getpid ()> on every iteration of the loop,	335	This works by calling C<getpid ()> on every iteration of the loop,
315	and thus this might slow down your event loop if you do a lot of loop	336	and thus this might slow down your event loop if you do a lot of loop
316	iterations and little real work, but is usually not noticeable (on my	337	iterations and little real work, but is usually not noticeable (on my
317	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence	338	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence
318	without a syscall and thus I<very> fast, but my GNU/Linux system also has	339	without a system call and thus I<very> fast, but my GNU/Linux system also has
319	C<pthread_atfork> which is even faster).	340	C<pthread_atfork> which is even faster).
320		341
321	The big advantage of this flag is that you can forget about fork (and	342	The big advantage of this flag is that you can forget about fork (and
322	forget about forgetting to tell libev about forking) when you use this	343	forget about forgetting to tell libev about forking) when you use this
323	flag.	344	flag.
324		345
325	This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS>	346	This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS>
326	environment variable.	347	environment variable.
327		348
328	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	349	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
329		350
330	This is your standard select(2) backend. Not I<completely> standard, as	351	This is your standard select(2) backend. Not I<completely> standard, as
…		…
332	but if that fails, expect a fairly low limit on the number of fds when	353	but if that fails, expect a fairly low limit on the number of fds when
333	using this backend. It doesn't scale too well (O(highest_fd)), but its	354	using this backend. It doesn't scale too well (O(highest_fd)), but its
334	usually the fastest backend for a low number of (low-numbered :) fds.	355	usually the fastest backend for a low number of (low-numbered :) fds.
335		356
336	To get good performance out of this backend you need a high amount of	357	To get good performance out of this backend you need a high amount of
337	parallelity (most of the file descriptors should be busy). If you are	358	parallelism (most of the file descriptors should be busy). If you are
338	writing a server, you should C<accept ()> in a loop to accept as many	359	writing a server, you should C<accept ()> in a loop to accept as many
339	connections as possible during one iteration. You might also want to have	360	connections as possible during one iteration. You might also want to have
340	a look at C<ev_set_io_collect_interval ()> to increase the amount of	361	a look at C<ev_set_io_collect_interval ()> to increase the amount of
341	readyness notifications you get per iteration.	362	readiness notifications you get per iteration.
342		363
343	=item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows)	364	=item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows)
344		365
345	And this is your standard poll(2) backend. It's more complicated	366	And this is your standard poll(2) backend. It's more complicated
346	than select, but handles sparse fds better and has no artificial	367	than select, but handles sparse fds better and has no artificial
…		…
354	For few fds, this backend is a bit little slower than poll and select,	375	For few fds, this backend is a bit little slower than poll and select,
355	but it scales phenomenally better. While poll and select usually scale	376	but it scales phenomenally better. While poll and select usually scale
356	like O(total_fds) where n is the total number of fds (or the highest fd),	377	like O(total_fds) where n is the total number of fds (or the highest fd),
357	epoll scales either O(1) or O(active_fds). The epoll design has a number	378	epoll scales either O(1) or O(active_fds). The epoll design has a number
358	of shortcomings, such as silently dropping events in some hard-to-detect	379	of shortcomings, such as silently dropping events in some hard-to-detect
359	cases and rewiring a syscall per fd change, no fork support and bad	380	cases and requiring a system call per fd change, no fork support and bad
360	support for dup.	381	support for dup.
361		382
362	While stopping, setting and starting an I/O watcher in the same iteration	383	While stopping, setting and starting an I/O watcher in the same iteration
363	will result in some caching, there is still a syscall per such incident	384	will result in some caching, there is still a system call per such incident
364	(because the fd could point to a different file description now), so its	385	(because the fd could point to a different file description now), so its
365	best to avoid that. Also, C<dup ()>'ed file descriptors might not work	386	best to avoid that. Also, C<dup ()>'ed file descriptors might not work
366	very well if you register events for both fds.	387	very well if you register events for both fds.
367		388
368	Please note that epoll sometimes generates spurious notifications, so you	389	Please note that epoll sometimes generates spurious notifications, so you
…		…
371		392
372	Best performance from this backend is achieved by not unregistering all	393	Best performance from this backend is achieved by not unregistering all
373	watchers for a file descriptor until it has been closed, if possible, i.e.	394	watchers for a file descriptor until it has been closed, if possible, i.e.
374	keep at least one watcher active per fd at all times.	395	keep at least one watcher active per fd at all times.
375		396
376	While nominally embeddeble in other event loops, this feature is broken in	397	While nominally embeddable in other event loops, this feature is broken in
377	all kernel versions tested so far.	398	all kernel versions tested so far.
378		399
379	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)	400	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)
380		401
381	Kqueue deserves special mention, as at the time of this writing, it	402	Kqueue deserves special mention, as at the time of this writing, it
382	was broken on all BSDs except NetBSD (usually it doesn't work reliably	403	was broken on all BSDs except NetBSD (usually it doesn't work reliably
383	with anything but sockets and pipes, except on Darwin, where of course	404	with anything but sockets and pipes, except on Darwin, where of course
384	it's completely useless). For this reason it's not being "autodetected"	405	it's completely useless). For this reason it's not being "auto-detected"
385	unless you explicitly specify it explicitly in the flags (i.e. using	406	unless you explicitly specify it explicitly in the flags (i.e. using
386	C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough)	407	C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough)
387	system like NetBSD.	408	system like NetBSD.
388		409
389	You still can embed kqueue into a normal poll or select backend and use it	410	You still can embed kqueue into a normal poll or select backend and use it
…		…
391	the target platform). See C<ev_embed> watchers for more info.	412	the target platform). See C<ev_embed> watchers for more info.
392		413
393	It scales in the same way as the epoll backend, but the interface to the	414	It scales in the same way as the epoll backend, but the interface to the
394	kernel is more efficient (which says nothing about its actual speed, of	415	kernel is more efficient (which says nothing about its actual speed, of
395	course). While stopping, setting and starting an I/O watcher does never	416	course). While stopping, setting and starting an I/O watcher does never
396	cause an extra syscall as with C<EVBACKEND_EPOLL>, it still adds up to	417	cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to
397	two event changes per incident, support for C<fork ()> is very bad and it	418	two event changes per incident, support for C<fork ()> is very bad and it
398	drops fds silently in similarly hard-to-detect cases.	419	drops fds silently in similarly hard-to-detect cases.
399		420
400	This backend usually performs well under most conditions.	421	This backend usually performs well under most conditions.
401		422
…		…
416	=item C<EVBACKEND_PORT> (value 32, Solaris 10)	437	=item C<EVBACKEND_PORT> (value 32, Solaris 10)
417		438
418	This uses the Solaris 10 event port mechanism. As with everything on Solaris,	439	This uses the Solaris 10 event port mechanism. As with everything on Solaris,
419	it's really slow, but it still scales very well (O(active_fds)).	440	it's really slow, but it still scales very well (O(active_fds)).
420		441
421	Please note that solaris event ports can deliver a lot of spurious	442	Please note that Solaris event ports can deliver a lot of spurious
422	notifications, so you need to use non-blocking I/O or other means to avoid	443	notifications, so you need to use non-blocking I/O or other means to avoid
423	blocking when no data (or space) is available.	444	blocking when no data (or space) is available.
424		445
425	While this backend scales well, it requires one system call per active	446	While this backend scales well, it requires one system call per active
426	file descriptor per loop iteration. For small and medium numbers of file	447	file descriptor per loop iteration. For small and medium numbers of file
427	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend	448	descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend
428	might perform better.	449	might perform better.
429		450
430	On the positive side, ignoring the spurious readyness notifications, this	451	On the positive side, ignoring the spurious readiness notifications, this
431	backend actually performed to specification in all tests and is fully	452	backend actually performed to specification in all tests and is fully
432	embeddable, which is a rare feat among the OS-specific backends.	453	embeddable, which is a rare feat among the OS-specific backends.
433		454
434	=item C<EVBACKEND_ALL>	455	=item C<EVBACKEND_ALL>
435		456
…		…
439		460
440	It is definitely not recommended to use this flag.	461	It is definitely not recommended to use this flag.
441		462
442	=back	463	=back
443		464
444	If one or more of these are ored into the flags value, then only these	465	If one or more of these are or'ed into the flags value, then only these
445	backends will be tried (in the reverse order as listed here). If none are	466	backends will be tried (in the reverse order as listed here). If none are
446	specified, all backends in C<ev_recommended_backends ()> will be tried.	467	specified, all backends in C<ev_recommended_backends ()> will be tried.
447		468
448	The most typical usage is like this:	469	The most typical usage is like this:
449		470
450	if (!ev_default_loop (0))	471	if (!ev_default_loop (0))
451	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");	472	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
452		473
453	Restrict libev to the select and poll backends, and do not allow	474	Restrict libev to the select and poll backends, and do not allow
454	environment settings to be taken into account:	475	environment settings to be taken into account:
455		476
456	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);	477	ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV);
457		478
458	Use whatever libev has to offer, but make sure that kqueue is used if	479	Use whatever libev has to offer, but make sure that kqueue is used if
459	available (warning, breaks stuff, best use only with your own private	480	available (warning, breaks stuff, best use only with your own private
460	event loop and only if you know the OS supports your types of fds):	481	event loop and only if you know the OS supports your types of fds):
461		482
462	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);	483	ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE);
463		484
464	=item struct ev_loop *ev_loop_new (unsigned int flags)	485	=item struct ev_loop *ev_loop_new (unsigned int flags)
465		486
466	Similar to C<ev_default_loop>, but always creates a new event loop that is	487	Similar to C<ev_default_loop>, but always creates a new event loop that is
467	always distinct from the default loop. Unlike the default loop, it cannot	488	always distinct from the default loop. Unlike the default loop, it cannot
468	handle signal and child watchers, and attempts to do so will be greeted by	489	handle signal and child watchers, and attempts to do so will be greeted by
469	undefined behaviour (or a failed assertion if assertions are enabled).	490	undefined behaviour (or a failed assertion if assertions are enabled).
470		491
		492	Note that this function I<is> thread-safe, and the recommended way to use
		493	libev with threads is indeed to create one loop per thread, and using the
		494	default loop in the "main" or "initial" thread.
		495
471	Example: Try to create a event loop that uses epoll and nothing else.	496	Example: Try to create a event loop that uses epoll and nothing else.
472		497
473	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);	498	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
474	if (!epoller)	499	if (!epoller)
475	fatal ("no epoll found here, maybe it hides under your chair");	500	fatal ("no epoll found here, maybe it hides under your chair");
476		501
477	=item ev_default_destroy ()	502	=item ev_default_destroy ()
478		503
479	Destroys the default loop again (frees all memory and kernel state	504	Destroys the default loop again (frees all memory and kernel state
480	etc.). None of the active event watchers will be stopped in the normal	505	etc.). None of the active event watchers will be stopped in the normal
481	sense, so e.g. C<ev_is_active> might still return true. It is your	506	sense, so e.g. C<ev_is_active> might still return true. It is your
482	responsibility to either stop all watchers cleanly yoursef I<before>	507	responsibility to either stop all watchers cleanly yourself I<before>
483	calling this function, or cope with the fact afterwards (which is usually	508	calling this function, or cope with the fact afterwards (which is usually
484	the easiest thing, you can just ignore the watchers and/or C<free ()> them	509	the easiest thing, you can just ignore the watchers and/or C<free ()> them
485	for example).	510	for example).
486		511
487	Note that certain global state, such as signal state, will not be freed by	512	Note that certain global state, such as signal state, will not be freed by
…		…
568	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle	593	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle
569	those events and any outstanding ones, but will not block your process in	594	those events and any outstanding ones, but will not block your process in
570	case there are no events and will return after one iteration of the loop.	595	case there are no events and will return after one iteration of the loop.
571		596
572	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if	597	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if
573	neccessary) and will handle those and any outstanding ones. It will block	598	necessary) and will handle those and any outstanding ones. It will block
574	your process until at least one new event arrives, and will return after	599	your process until at least one new event arrives, and will return after
575	one iteration of the loop. This is useful if you are waiting for some	600	one iteration of the loop. This is useful if you are waiting for some
576	external event in conjunction with something not expressible using other	601	external event in conjunction with something not expressible using other
577	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is	602	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is
578	usually a better approach for this kind of thing.	603	usually a better approach for this kind of thing.
…		…
639	respectively).	664	respectively).
640		665
641	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	666	Example: Create a signal watcher, but keep it from keeping C<ev_loop>
642	running when nothing else is active.	667	running when nothing else is active.
643		668
644	struct ev_signal exitsig;	669	struct ev_signal exitsig;
645	ev_signal_init (&exitsig, sig_cb, SIGINT);	670	ev_signal_init (&exitsig, sig_cb, SIGINT);
646	ev_signal_start (loop, &exitsig);	671	ev_signal_start (loop, &exitsig);
647	evf_unref (loop);	672	evf_unref (loop);
648		673
649	Example: For some weird reason, unregister the above signal handler again.	674	Example: For some weird reason, unregister the above signal handler again.
650		675
651	ev_ref (loop);	676	ev_ref (loop);
652	ev_signal_stop (loop, &exitsig);	677	ev_signal_stop (loop, &exitsig);
653		678
654	=item ev_set_io_collect_interval (loop, ev_tstamp interval)	679	=item ev_set_io_collect_interval (loop, ev_tstamp interval)
655		680
656	=item ev_set_timeout_collect_interval (loop, ev_tstamp interval)	681	=item ev_set_timeout_collect_interval (loop, ev_tstamp interval)
657		682
…		…
679	to spend more time collecting timeouts, at the expense of increased	704	to spend more time collecting timeouts, at the expense of increased
680	latency (the watcher callback will be called later). C<ev_io> watchers	705	latency (the watcher callback will be called later). C<ev_io> watchers
681	will not be affected. Setting this to a non-null value will not introduce	706	will not be affected. Setting this to a non-null value will not introduce
682	any overhead in libev.	707	any overhead in libev.
683		708
684	Many (busy) programs can usually benefit by setting the io collect	709	Many (busy) programs can usually benefit by setting the I/O collect
685	interval to a value near C<0.1> or so, which is often enough for	710	interval to a value near C<0.1> or so, which is often enough for
686	interactive servers (of course not for games), likewise for timeouts. It	711	interactive servers (of course not for games), likewise for timeouts. It
687	usually doesn't make much sense to set it to a lower value than C<0.01>,	712	usually doesn't make much sense to set it to a lower value than C<0.01>,
688	as this approsaches the timing granularity of most systems.	713	as this approaches the timing granularity of most systems.
		714
		715	=item ev_loop_verify (loop)
		716
		717	This function only does something when C<EV_VERIFY> support has been
		718	compiled in. It tries to go through all internal structures and checks
		719	them for validity. If anything is found to be inconsistent, it will print
		720	an error message to standard error and call C<abort ()>.
		721
		722	This can be used to catch bugs inside libev itself: under normal
		723	circumstances, this function will never abort as of course libev keeps its
		724	data structures consistent.
689		725
690	=back	726	=back
691		727
692		728
693	=head1 ANATOMY OF A WATCHER	729	=head1 ANATOMY OF A WATCHER
694		730
695	A watcher is a structure that you create and register to record your	731	A watcher is a structure that you create and register to record your
696	interest in some event. For instance, if you want to wait for STDIN to	732	interest in some event. For instance, if you want to wait for STDIN to
697	become readable, you would create an C<ev_io> watcher for that:	733	become readable, you would create an C<ev_io> watcher for that:
698		734
699	static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)	735	static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)
700	{	736	{
701	ev_io_stop (w);	737	ev_io_stop (w);
702	ev_unloop (loop, EVUNLOOP_ALL);	738	ev_unloop (loop, EVUNLOOP_ALL);
703	}	739	}
704		740
705	struct ev_loop *loop = ev_default_loop (0);	741	struct ev_loop *loop = ev_default_loop (0);
706	struct ev_io stdin_watcher;	742	struct ev_io stdin_watcher;
707	ev_init (&stdin_watcher, my_cb);	743	ev_init (&stdin_watcher, my_cb);
708	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	744	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
709	ev_io_start (loop, &stdin_watcher);	745	ev_io_start (loop, &stdin_watcher);
710	ev_loop (loop, 0);	746	ev_loop (loop, 0);
711		747
712	As you can see, you are responsible for allocating the memory for your	748	As you can see, you are responsible for allocating the memory for your
713	watcher structures (and it is usually a bad idea to do this on the stack,	749	watcher structures (and it is usually a bad idea to do this on the stack,
714	although this can sometimes be quite valid).	750	although this can sometimes be quite valid).
715		751
716	Each watcher structure must be initialised by a call to C<ev_init	752	Each watcher structure must be initialised by a call to C<ev_init
717	(watcher *, callback)>, which expects a callback to be provided. This	753	(watcher *, callback)>, which expects a callback to be provided. This
718	callback gets invoked each time the event occurs (or, in the case of io	754	callback gets invoked each time the event occurs (or, in the case of I/O
719	watchers, each time the event loop detects that the file descriptor given	755	watchers, each time the event loop detects that the file descriptor given
720	is readable and/or writable).	756	is readable and/or writable).
721		757
722	Each watcher type has its own C<< ev_<type>_set (watcher *, ...) >> macro	758	Each watcher type has its own C<< ev_<type>_set (watcher *, ...) >> macro
723	with arguments specific to this watcher type. There is also a macro	759	with arguments specific to this watcher type. There is also a macro
…		…
799		835
800	The given async watcher has been asynchronously notified (see C<ev_async>).	836	The given async watcher has been asynchronously notified (see C<ev_async>).
801		837
802	=item C<EV_ERROR>	838	=item C<EV_ERROR>
803		839
804	An unspecified error has occured, the watcher has been stopped. This might	840	An unspecified error has occurred, the watcher has been stopped. This might
805	happen because the watcher could not be properly started because libev	841	happen because the watcher could not be properly started because libev
806	ran out of memory, a file descriptor was found to be closed or any other	842	ran out of memory, a file descriptor was found to be closed or any other
807	problem. You best act on it by reporting the problem and somehow coping	843	problem. You best act on it by reporting the problem and somehow coping
808	with the watcher being stopped.	844	with the watcher being stopped.
809		845
810	Libev will usually signal a few "dummy" events together with an error,	846	Libev will usually signal a few "dummy" events together with an error,
811	for example it might indicate that a fd is readable or writable, and if	847	for example it might indicate that a fd is readable or writable, and if
812	your callbacks is well-written it can just attempt the operation and cope	848	your callbacks is well-written it can just attempt the operation and cope
813	with the error from read() or write(). This will not work in multithreaded	849	with the error from read() or write(). This will not work in multi-threaded
814	programs, though, so beware.	850	programs, though, so beware.
815		851
816	=back	852	=back
817		853
818	=head2 GENERIC WATCHER FUNCTIONS	854	=head2 GENERIC WATCHER FUNCTIONS
…		…
848	Although some watcher types do not have type-specific arguments	884	Although some watcher types do not have type-specific arguments
849	(e.g. C<ev_prepare>) you still need to call its C<set> macro.	885	(e.g. C<ev_prepare>) you still need to call its C<set> macro.
850		886
851	=item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args])	887	=item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args])
852		888
853	This convinience macro rolls both C<ev_init> and C<ev_TYPE_set> macro	889	This convenience macro rolls both C<ev_init> and C<ev_TYPE_set> macro
854	calls into a single call. This is the most convinient method to initialise	890	calls into a single call. This is the most convenient method to initialise
855	a watcher. The same limitations apply, of course.	891	a watcher. The same limitations apply, of course.
856		892
857	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)	893	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)
858		894
859	Starts (activates) the given watcher. Only active watchers will receive	895	Starts (activates) the given watcher. Only active watchers will receive
…		…
942	to associate arbitrary data with your watcher. If you need more data and	978	to associate arbitrary data with your watcher. If you need more data and
943	don't want to allocate memory and store a pointer to it in that data	979	don't want to allocate memory and store a pointer to it in that data
944	member, you can also "subclass" the watcher type and provide your own	980	member, you can also "subclass" the watcher type and provide your own
945	data:	981	data:
946		982
947	struct my_io	983	struct my_io
948	{	984	{
949	struct ev_io io;	985	struct ev_io io;
950	int otherfd;	986	int otherfd;
951	void *somedata;	987	void *somedata;
952	struct whatever *mostinteresting;	988	struct whatever *mostinteresting;
953	}	989	}
954		990
955	And since your callback will be called with a pointer to the watcher, you	991	And since your callback will be called with a pointer to the watcher, you
956	can cast it back to your own type:	992	can cast it back to your own type:
957		993
958	static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents)	994	static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents)
959	{	995	{
960	struct my_io *w = (struct my_io *)w_;	996	struct my_io *w = (struct my_io *)w_;
961	...	997	...
962	}	998	}
963		999
964	More interesting and less C-conformant ways of casting your callback type	1000	More interesting and less C-conformant ways of casting your callback type
965	instead have been omitted.	1001	instead have been omitted.
966		1002
967	Another common scenario is having some data structure with multiple	1003	Another common scenario is having some data structure with multiple
968	watchers:	1004	watchers:
969		1005
970	struct my_biggy	1006	struct my_biggy
971	{	1007	{
972	int some_data;	1008	int some_data;
973	ev_timer t1;	1009	ev_timer t1;
974	ev_timer t2;	1010	ev_timer t2;
975	}	1011	}
976		1012
977	In this case getting the pointer to C<my_biggy> is a bit more complicated,	1013	In this case getting the pointer to C<my_biggy> is a bit more complicated,
978	you need to use C<offsetof>:	1014	you need to use C<offsetof>:
979		1015
980	#include <stddef.h>	1016	#include <stddef.h>
981		1017
982	static void	1018	static void
983	t1_cb (EV_P_ struct ev_timer *w, int revents)	1019	t1_cb (EV_P_ struct ev_timer *w, int revents)
984	{	1020	{
985	struct my_biggy big = (struct my_biggy *	1021	struct my_biggy big = (struct my_biggy *
986	(((char *)w) - offsetof (struct my_biggy, t1));	1022	(((char *)w) - offsetof (struct my_biggy, t1));
987	}	1023	}
988		1024
989	static void	1025	static void
990	t2_cb (EV_P_ struct ev_timer *w, int revents)	1026	t2_cb (EV_P_ struct ev_timer *w, int revents)
991	{	1027	{
992	struct my_biggy big = (struct my_biggy *	1028	struct my_biggy big = (struct my_biggy *
993	(((char *)w) - offsetof (struct my_biggy, t2));	1029	(((char *)w) - offsetof (struct my_biggy, t2));
994	}	1030	}
995		1031
996		1032
997	=head1 WATCHER TYPES	1033	=head1 WATCHER TYPES
998		1034
999	This section describes each watcher in detail, but will not repeat	1035	This section describes each watcher in detail, but will not repeat
…		…
1028	If you must do this, then force the use of a known-to-be-good backend	1064	If you must do this, then force the use of a known-to-be-good backend
1029	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and	1065	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and
1030	C<EVBACKEND_POLL>).	1066	C<EVBACKEND_POLL>).
1031		1067
1032	Another thing you have to watch out for is that it is quite easy to	1068	Another thing you have to watch out for is that it is quite easy to
1033	receive "spurious" readyness notifications, that is your callback might	1069	receive "spurious" readiness notifications, that is your callback might
1034	be called with C<EV_READ> but a subsequent C<read>(2) will actually block	1070	be called with C<EV_READ> but a subsequent C<read>(2) will actually block
1035	because there is no data. Not only are some backends known to create a	1071	because there is no data. Not only are some backends known to create a
1036	lot of those (for example solaris ports), it is very easy to get into	1072	lot of those (for example Solaris ports), it is very easy to get into
1037	this situation even with a relatively standard program structure. Thus	1073	this situation even with a relatively standard program structure. Thus
1038	it is best to always use non-blocking I/O: An extra C<read>(2) returning	1074	it is best to always use non-blocking I/O: An extra C<read>(2) returning
1039	C<EAGAIN> is far preferable to a program hanging until some data arrives.	1075	C<EAGAIN> is far preferable to a program hanging until some data arrives.
1040		1076
1041	If you cannot run the fd in non-blocking mode (for example you should not	1077	If you cannot run the fd in non-blocking mode (for example you should not
1042	play around with an Xlib connection), then you have to seperately re-test	1078	play around with an Xlib connection), then you have to separately re-test
1043	whether a file descriptor is really ready with a known-to-be good interface	1079	whether a file descriptor is really ready with a known-to-be good interface
1044	such as poll (fortunately in our Xlib example, Xlib already does this on	1080	such as poll (fortunately in our Xlib example, Xlib already does this on
1045	its own, so its quite safe to use).	1081	its own, so its quite safe to use).
1046		1082
1047	=head3 The special problem of disappearing file descriptors	1083	=head3 The special problem of disappearing file descriptors
…		…
1107	=item ev_io_init (ev_io *, callback, int fd, int events)	1143	=item ev_io_init (ev_io *, callback, int fd, int events)
1108		1144
1109	=item ev_io_set (ev_io *, int fd, int events)	1145	=item ev_io_set (ev_io *, int fd, int events)
1110		1146
1111	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to	1147	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to
1112	rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or	1148	receive events for and events is either C<EV_READ>, C<EV_WRITE> or
1113	C<EV_READ | EV_WRITE> to receive the given events.	1149	C<EV_READ | EV_WRITE> to receive the given events.
1114		1150
1115	=item int fd [read-only]	1151	=item int fd [read-only]
1116		1152
1117	The file descriptor being watched.	1153	The file descriptor being watched.
…		…
1126		1162
1127	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well	1163	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well
1128	readable, but only once. Since it is likely line-buffered, you could	1164	readable, but only once. Since it is likely line-buffered, you could
1129	attempt to read a whole line in the callback.	1165	attempt to read a whole line in the callback.
1130		1166
1131	static void	1167	static void
1132	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1168	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1133	{	1169	{
1134	ev_io_stop (loop, w);	1170	ev_io_stop (loop, w);
1135	.. read from stdin here (or from w->fd) and haqndle any I/O errors	1171	.. read from stdin here (or from w->fd) and haqndle any I/O errors
1136	}	1172	}
1137		1173
1138	...	1174	...
1139	struct ev_loop *loop = ev_default_init (0);	1175	struct ev_loop *loop = ev_default_init (0);
1140	struct ev_io stdin_readable;	1176	struct ev_io stdin_readable;
1141	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1177	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1142	ev_io_start (loop, &stdin_readable);	1178	ev_io_start (loop, &stdin_readable);
1143	ev_loop (loop, 0);	1179	ev_loop (loop, 0);
1144		1180
1145		1181
1146	=head2 C<ev_timer> - relative and optionally repeating timeouts	1182	=head2 C<ev_timer> - relative and optionally repeating timeouts
1147		1183
1148	Timer watchers are simple relative timers that generate an event after a	1184	Timer watchers are simple relative timers that generate an event after a
1149	given time, and optionally repeating in regular intervals after that.	1185	given time, and optionally repeating in regular intervals after that.
1150		1186
1151	The timers are based on real time, that is, if you register an event that	1187	The timers are based on real time, that is, if you register an event that
1152	times out after an hour and you reset your system clock to last years	1188	times out after an hour and you reset your system clock to January last
1153	time, it will still time out after (roughly) and hour. "Roughly" because	1189	year, it will still time out after (roughly) and hour. "Roughly" because
1154	detecting time jumps is hard, and some inaccuracies are unavoidable (the	1190	detecting time jumps is hard, and some inaccuracies are unavoidable (the
1155	monotonic clock option helps a lot here).	1191	monotonic clock option helps a lot here).
1156		1192
1157	The relative timeouts are calculated relative to the C<ev_now ()>	1193	The relative timeouts are calculated relative to the C<ev_now ()>
1158	time. This is usually the right thing as this timestamp refers to the time	1194	time. This is usually the right thing as this timestamp refers to the time
…		…
1160	you suspect event processing to be delayed and you I<need> to base the timeout	1196	you suspect event processing to be delayed and you I<need> to base the timeout
1161	on the current time, use something like this to adjust for this:	1197	on the current time, use something like this to adjust for this:
1162		1198
1163	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);	1199	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);
1164		1200
1165	The callback is guarenteed to be invoked only when its timeout has passed,	1201	The callback is guaranteed to be invoked only after its timeout has passed,
1166	but if multiple timers become ready during the same loop iteration then	1202	but if multiple timers become ready during the same loop iteration then
1167	order of execution is undefined.	1203	order of execution is undefined.
1168		1204
1169	=head3 Watcher-Specific Functions and Data Members	1205	=head3 Watcher-Specific Functions and Data Members
1170		1206
…		…
1172		1208
1173	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	1209	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
1174		1210
1175	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)	1211	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)
1176		1212
1177	Configure the timer to trigger after C<after> seconds. If C<repeat> is	1213	Configure the timer to trigger after C<after> seconds. If C<repeat>
1178	C<0.>, then it will automatically be stopped. If it is positive, then the	1214	is C<0.>, then it will automatically be stopped once the timeout is
1179	timer will automatically be configured to trigger again C<repeat> seconds	1215	reached. If it is positive, then the timer will automatically be
1180	later, again, and again, until stopped manually.	1216	configured to trigger again C<repeat> seconds later, again, and again,
		1217	until stopped manually.
1181		1218
1182	The timer itself will do a best-effort at avoiding drift, that is, if you	1219	The timer itself will do a best-effort at avoiding drift, that is, if
1183	configure a timer to trigger every 10 seconds, then it will trigger at	1220	you configure a timer to trigger every 10 seconds, then it will normally
1184	exactly 10 second intervals. If, however, your program cannot keep up with	1221	trigger at exactly 10 second intervals. If, however, your program cannot
1185	the timer (because it takes longer than those 10 seconds to do stuff) the	1222	keep up with the timer (because it takes longer than those 10 seconds to
1186	timer will not fire more than once per event loop iteration.	1223	do stuff) the timer will not fire more than once per event loop iteration.
1187		1224
1188	=item ev_timer_again (loop, ev_timer *)	1225	=item ev_timer_again (loop, ev_timer *)
1189		1226
1190	This will act as if the timer timed out and restart it again if it is	1227	This will act as if the timer timed out and restart it again if it is
1191	repeating. The exact semantics are:	1228	repeating. The exact semantics are:
1192		1229
1193	If the timer is pending, its pending status is cleared.	1230	If the timer is pending, its pending status is cleared.
1194		1231
1195	If the timer is started but nonrepeating, stop it (as if it timed out).	1232	If the timer is started but non-repeating, stop it (as if it timed out).
1196		1233
1197	If the timer is repeating, either start it if necessary (with the	1234	If the timer is repeating, either start it if necessary (with the
1198	C<repeat> value), or reset the running timer to the C<repeat> value.	1235	C<repeat> value), or reset the running timer to the C<repeat> value.
1199		1236
1200	This sounds a bit complicated, but here is a useful and typical	1237	This sounds a bit complicated, but here is a useful and typical
1201	example: Imagine you have a tcp connection and you want a so-called idle	1238	example: Imagine you have a TCP connection and you want a so-called idle
1202	timeout, that is, you want to be called when there have been, say, 60	1239	timeout, that is, you want to be called when there have been, say, 60
1203	seconds of inactivity on the socket. The easiest way to do this is to	1240	seconds of inactivity on the socket. The easiest way to do this is to
1204	configure an C<ev_timer> with a C<repeat> value of C<60> and then call	1241	configure an C<ev_timer> with a C<repeat> value of C<60> and then call
1205	C<ev_timer_again> each time you successfully read or write some data. If	1242	C<ev_timer_again> each time you successfully read or write some data. If
1206	you go into an idle state where you do not expect data to travel on the	1243	you go into an idle state where you do not expect data to travel on the
…		…
1232		1269
1233	=head3 Examples	1270	=head3 Examples
1234		1271
1235	Example: Create a timer that fires after 60 seconds.	1272	Example: Create a timer that fires after 60 seconds.
1236		1273
1237	static void	1274	static void
1238	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1275	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1239	{	1276	{
1240	.. one minute over, w is actually stopped right here	1277	.. one minute over, w is actually stopped right here
1241	}	1278	}
1242		1279
1243	struct ev_timer mytimer;	1280	struct ev_timer mytimer;
1244	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1281	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
1245	ev_timer_start (loop, &mytimer);	1282	ev_timer_start (loop, &mytimer);
1246		1283
1247	Example: Create a timeout timer that times out after 10 seconds of	1284	Example: Create a timeout timer that times out after 10 seconds of
1248	inactivity.	1285	inactivity.
1249		1286
1250	static void	1287	static void
1251	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1288	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1252	{	1289	{
1253	.. ten seconds without any activity	1290	.. ten seconds without any activity
1254	}	1291	}
1255		1292
1256	struct ev_timer mytimer;	1293	struct ev_timer mytimer;
1257	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	1294	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1258	ev_timer_again (&mytimer); /* start timer */	1295	ev_timer_again (&mytimer); /* start timer */
1259	ev_loop (loop, 0);	1296	ev_loop (loop, 0);
1260		1297
1261	// and in some piece of code that gets executed on any "activity":	1298	// and in some piece of code that gets executed on any "activity":
1262	// reset the timeout to start ticking again at 10 seconds	1299	// reset the timeout to start ticking again at 10 seconds
1263	ev_timer_again (&mytimer);	1300	ev_timer_again (&mytimer);
1264		1301
1265		1302
1266	=head2 C<ev_periodic> - to cron or not to cron?	1303	=head2 C<ev_periodic> - to cron or not to cron?
1267		1304
1268	Periodic watchers are also timers of a kind, but they are very versatile	1305	Periodic watchers are also timers of a kind, but they are very versatile
1269	(and unfortunately a bit complex).	1306	(and unfortunately a bit complex).
1270		1307
1271	Unlike C<ev_timer>'s, they are not based on real time (or relative time)	1308	Unlike C<ev_timer>'s, they are not based on real time (or relative time)
1272	but on wallclock time (absolute time). You can tell a periodic watcher	1309	but on wall clock time (absolute time). You can tell a periodic watcher
1273	to trigger "at" some specific point in time. For example, if you tell a	1310	to trigger after some specific point in time. For example, if you tell a
1274	periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now ()	1311	periodic watcher to trigger in 10 seconds (by specifying e.g. C<ev_now ()
1275	+ 10.>) and then reset your system clock to the last year, then it will	1312	+ 10.>, that is, an absolute time not a delay) and then reset your system
		1313	clock to January of the previous year, then it will take more than year
1276	take a year to trigger the event (unlike an C<ev_timer>, which would trigger	1314	to trigger the event (unlike an C<ev_timer>, which would still trigger
1277	roughly 10 seconds later).	1315	roughly 10 seconds later as it uses a relative timeout).
1278		1316
1279	They can also be used to implement vastly more complex timers, such as	1317	C<ev_periodic>s can also be used to implement vastly more complex timers,
1280	triggering an event on each midnight, local time or other, complicated,	1318	such as triggering an event on each "midnight, local time", or other
1281	rules.	1319	complicated, rules.
1282		1320
1283	As with timers, the callback is guarenteed to be invoked only when the	1321	As with timers, the callback is guaranteed to be invoked only when the
1284	time (C<at>) has been passed, but if multiple periodic timers become ready	1322	time (C<at>) has passed, but if multiple periodic timers become ready
1285	during the same loop iteration then order of execution is undefined.	1323	during the same loop iteration then order of execution is undefined.
1286		1324
1287	=head3 Watcher-Specific Functions and Data Members	1325	=head3 Watcher-Specific Functions and Data Members
1288		1326
1289	=over 4	1327	=over 4
…		…
1297		1335
1298	=over 4	1336	=over 4
1299		1337
1300	=item * absolute timer (at = time, interval = reschedule_cb = 0)	1338	=item * absolute timer (at = time, interval = reschedule_cb = 0)
1301		1339
1302	In this configuration the watcher triggers an event at the wallclock time	1340	In this configuration the watcher triggers an event after the wall clock
1303	C<at> and doesn't repeat. It will not adjust when a time jump occurs,	1341	time C<at> has passed and doesn't repeat. It will not adjust when a time
1304	that is, if it is to be run at January 1st 2011 then it will run when the	1342	jump occurs, that is, if it is to be run at January 1st 2011 then it will
1305	system time reaches or surpasses this time.	1343	run when the system time reaches or surpasses this time.
1306		1344
1307	=item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)	1345	=item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
1308		1346
1309	In this mode the watcher will always be scheduled to time out at the next	1347	In this mode the watcher will always be scheduled to time out at the next
1310	C<at + N * interval> time (for some integer N, which can also be negative)	1348	C<at + N * interval> time (for some integer N, which can also be negative)
1311	and then repeat, regardless of any time jumps.	1349	and then repeat, regardless of any time jumps.
1312		1350
1313	This can be used to create timers that do not drift with respect to system	1351	This can be used to create timers that do not drift with respect to system
1314	time:	1352	time, for example, here is a C<ev_periodic> that triggers each hour, on
		1353	the hour:
1315		1354
1316	ev_periodic_set (&periodic, 0., 3600., 0);	1355	ev_periodic_set (&periodic, 0., 3600., 0);
1317		1356
1318	This doesn't mean there will always be 3600 seconds in between triggers,	1357	This doesn't mean there will always be 3600 seconds in between triggers,
1319	but only that the the callback will be called when the system time shows a	1358	but only that the callback will be called when the system time shows a
1320	full hour (UTC), or more correctly, when the system time is evenly divisible	1359	full hour (UTC), or more correctly, when the system time is evenly divisible
1321	by 3600.	1360	by 3600.
1322		1361
1323	Another way to think about it (for the mathematically inclined) is that	1362	Another way to think about it (for the mathematically inclined) is that
1324	C<ev_periodic> will try to run the callback in this mode at the next possible	1363	C<ev_periodic> will try to run the callback in this mode at the next possible
1325	time where C<time = at (mod interval)>, regardless of any time jumps.	1364	time where C<time = at (mod interval)>, regardless of any time jumps.
1326		1365
1327	For numerical stability it is preferable that the C<at> value is near	1366	For numerical stability it is preferable that the C<at> value is near
1328	C<ev_now ()> (the current time), but there is no range requirement for	1367	C<ev_now ()> (the current time), but there is no range requirement for
1329	this value.	1368	this value, and in fact is often specified as zero.
		1369
		1370	Note also that there is an upper limit to how often a timer can fire (CPU
		1371	speed for example), so if C<interval> is very small then timing stability
		1372	will of course deteriorate. Libev itself tries to be exact to be about one
		1373	millisecond (if the OS supports it and the machine is fast enough).
1330		1374
1331	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)	1375	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
1332		1376
1333	In this mode the values for C<interval> and C<at> are both being	1377	In this mode the values for C<interval> and C<at> are both being
1334	ignored. Instead, each time the periodic watcher gets scheduled, the	1378	ignored. Instead, each time the periodic watcher gets scheduled, the
1335	reschedule callback will be called with the watcher as first, and the	1379	reschedule callback will be called with the watcher as first, and the
1336	current time as second argument.	1380	current time as second argument.
1337		1381
1338	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,	1382	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,
1339	ever, or make any event loop modifications>. If you need to stop it,	1383	ever, or make ANY event loop modifications whatsoever>.
1340	return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by
1341	starting an C<ev_prepare> watcher, which is legal).
1342		1384
		1385	If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop
		1386	it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the
		1387	only event loop modification you are allowed to do).
		1388
1343	Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w,	1389	The callback prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic
1344	ev_tstamp now)>, e.g.:	1390	*w, ev_tstamp now)>, e.g.:
1345		1391
1346	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	1392	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
1347	{	1393	{
1348	return now + 60.;	1394	return now + 60.;
1349	}	1395	}
…		…
1351	It must return the next time to trigger, based on the passed time value	1397	It must return the next time to trigger, based on the passed time value
1352	(that is, the lowest time value larger than to the second argument). It	1398	(that is, the lowest time value larger than to the second argument). It
1353	will usually be called just before the callback will be triggered, but	1399	will usually be called just before the callback will be triggered, but
1354	might be called at other times, too.	1400	might be called at other times, too.
1355		1401
1356	NOTE: I<< This callback must always return a time that is later than the	1402	NOTE: I<< This callback must always return a time that is higher than or
1357	passed C<now> value >>. Not even C<now> itself will do, it I<must> be larger.	1403	equal to the passed C<now> value >>.
1358		1404
1359	This can be used to create very complex timers, such as a timer that	1405	This can be used to create very complex timers, such as a timer that
1360	triggers on each midnight, local time. To do this, you would calculate the	1406	triggers on "next midnight, local time". To do this, you would calculate the
1361	next midnight after C<now> and return the timestamp value for this. How	1407	next midnight after C<now> and return the timestamp value for this. How
1362	you do this is, again, up to you (but it is not trivial, which is the main	1408	you do this is, again, up to you (but it is not trivial, which is the main
1363	reason I omitted it as an example).	1409	reason I omitted it as an example).
1364		1410
1365	=back	1411	=back
…		…
1369	Simply stops and restarts the periodic watcher again. This is only useful	1415	Simply stops and restarts the periodic watcher again. This is only useful
1370	when you changed some parameters or the reschedule callback would return	1416	when you changed some parameters or the reschedule callback would return
1371	a different time than the last time it was called (e.g. in a crond like	1417	a different time than the last time it was called (e.g. in a crond like
1372	program when the crontabs have changed).	1418	program when the crontabs have changed).
1373		1419
		1420	=item ev_tstamp ev_periodic_at (ev_periodic *)
		1421
		1422	When active, returns the absolute time that the watcher is supposed to
		1423	trigger next.
		1424
1374	=item ev_tstamp offset [read-write]	1425	=item ev_tstamp offset [read-write]
1375		1426
1376	When repeating, this contains the offset value, otherwise this is the	1427	When repeating, this contains the offset value, otherwise this is the
1377	absolute point in time (the C<at> value passed to C<ev_periodic_set>).	1428	absolute point in time (the C<at> value passed to C<ev_periodic_set>).
1378		1429
…		…
1389		1440
1390	The current reschedule callback, or C<0>, if this functionality is	1441	The current reschedule callback, or C<0>, if this functionality is
1391	switched off. Can be changed any time, but changes only take effect when	1442	switched off. Can be changed any time, but changes only take effect when
1392	the periodic timer fires or C<ev_periodic_again> is being called.	1443	the periodic timer fires or C<ev_periodic_again> is being called.
1393		1444
1394	=item ev_tstamp at [read-only]
1395
1396	When active, contains the absolute time that the watcher is supposed to
1397	trigger next.
1398
1399	=back	1445	=back
1400		1446
1401	=head3 Examples	1447	=head3 Examples
1402		1448
1403	Example: Call a callback every hour, or, more precisely, whenever the	1449	Example: Call a callback every hour, or, more precisely, whenever the
1404	system clock is divisible by 3600. The callback invocation times have	1450	system clock is divisible by 3600. The callback invocation times have
1405	potentially a lot of jittering, but good long-term stability.	1451	potentially a lot of jitter, but good long-term stability.
1406		1452
1407	static void	1453	static void
1408	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1454	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1409	{	1455	{
1410	... its now a full hour (UTC, or TAI or whatever your clock follows)	1456	... its now a full hour (UTC, or TAI or whatever your clock follows)
1411	}	1457	}
1412		1458
1413	struct ev_periodic hourly_tick;	1459	struct ev_periodic hourly_tick;
1414	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1460	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1415	ev_periodic_start (loop, &hourly_tick);	1461	ev_periodic_start (loop, &hourly_tick);
1416		1462
1417	Example: The same as above, but use a reschedule callback to do it:	1463	Example: The same as above, but use a reschedule callback to do it:
1418		1464
1419	#include <math.h>	1465	#include <math.h>
1420		1466
1421	static ev_tstamp	1467	static ev_tstamp
1422	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1468	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
1423	{	1469	{
1424	return fmod (now, 3600.) + 3600.;	1470	return fmod (now, 3600.) + 3600.;
1425	}	1471	}
1426		1472
1427	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1473	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1428		1474
1429	Example: Call a callback every hour, starting now:	1475	Example: Call a callback every hour, starting now:
1430		1476
1431	struct ev_periodic hourly_tick;	1477	struct ev_periodic hourly_tick;
1432	ev_periodic_init (&hourly_tick, clock_cb,	1478	ev_periodic_init (&hourly_tick, clock_cb,
1433	fmod (ev_now (loop), 3600.), 3600., 0);	1479	fmod (ev_now (loop), 3600.), 3600., 0);
1434	ev_periodic_start (loop, &hourly_tick);	1480	ev_periodic_start (loop, &hourly_tick);
1435		1481
1436		1482
1437	=head2 C<ev_signal> - signal me when a signal gets signalled!	1483	=head2 C<ev_signal> - signal me when a signal gets signalled!
1438		1484
1439	Signal watchers will trigger an event when the process receives a specific	1485	Signal watchers will trigger an event when the process receives a specific
…		…
1447	as you don't register any with libev). Similarly, when the last signal	1493	as you don't register any with libev). Similarly, when the last signal
1448	watcher for a signal is stopped libev will reset the signal handler to	1494	watcher for a signal is stopped libev will reset the signal handler to
1449	SIG_DFL (regardless of what it was set to before).	1495	SIG_DFL (regardless of what it was set to before).
1450		1496
1451	If possible and supported, libev will install its handlers with	1497	If possible and supported, libev will install its handlers with
1452	C<SA_RESTART> behaviour enabled, so syscalls should not be unduly	1498	C<SA_RESTART> behaviour enabled, so system calls should not be unduly
1453	interrupted. If you have a problem with syscalls getting interrupted by	1499	interrupted. If you have a problem with system calls getting interrupted by
1454	signals you can block all signals in an C<ev_check> watcher and unblock	1500	signals you can block all signals in an C<ev_check> watcher and unblock
1455	them in an C<ev_prepare> watcher.	1501	them in an C<ev_prepare> watcher.
1456		1502
1457	=head3 Watcher-Specific Functions and Data Members	1503	=head3 Watcher-Specific Functions and Data Members
1458		1504
…		…
1473		1519
1474	=head3 Examples	1520	=head3 Examples
1475		1521
1476	Example: Try to exit cleanly on SIGINT and SIGTERM.	1522	Example: Try to exit cleanly on SIGINT and SIGTERM.
1477		1523
1478	static void	1524	static void
1479	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)	1525	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1480	{	1526	{
1481	ev_unloop (loop, EVUNLOOP_ALL);	1527	ev_unloop (loop, EVUNLOOP_ALL);
1482	}	1528	}
1483		1529
1484	struct ev_signal signal_watcher;	1530	struct ev_signal signal_watcher;
1485	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1531	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1486	ev_signal_start (loop, &sigint_cb);	1532	ev_signal_start (loop, &sigint_cb);
1487		1533
1488		1534
1489	=head2 C<ev_child> - watch out for process status changes	1535	=head2 C<ev_child> - watch out for process status changes
1490		1536
1491	Child watchers trigger when your process receives a SIGCHLD in response to	1537	Child watchers trigger when your process receives a SIGCHLD in response to
…		…
1493	is permissible to install a child watcher I<after> the child has been	1539	is permissible to install a child watcher I<after> the child has been
1494	forked (which implies it might have already exited), as long as the event	1540	forked (which implies it might have already exited), as long as the event
1495	loop isn't entered (or is continued from a watcher).	1541	loop isn't entered (or is continued from a watcher).
1496		1542
1497	Only the default event loop is capable of handling signals, and therefore	1543	Only the default event loop is capable of handling signals, and therefore
1498	you can only rgeister child watchers in the default event loop.	1544	you can only register child watchers in the default event loop.
1499		1545
1500	=head3 Process Interaction	1546	=head3 Process Interaction
1501		1547
1502	Libev grabs C<SIGCHLD> as soon as the default event loop is	1548	Libev grabs C<SIGCHLD> as soon as the default event loop is
1503	initialised. This is necessary to guarantee proper behaviour even if	1549	initialised. This is necessary to guarantee proper behaviour even if
1504	the first child watcher is started after the child exits. The occurance	1550	the first child watcher is started after the child exits. The occurrence
1505	of C<SIGCHLD> is recorded asynchronously, but child reaping is done	1551	of C<SIGCHLD> is recorded asynchronously, but child reaping is done
1506	synchronously as part of the event loop processing. Libev always reaps all	1552	synchronously as part of the event loop processing. Libev always reaps all
1507	children, even ones not watched.	1553	children, even ones not watched.
1508		1554
1509	=head3 Overriding the Built-In Processing	1555	=head3 Overriding the Built-In Processing
…		…
1551	=head3 Examples	1597	=head3 Examples
1552		1598
1553	Example: C<fork()> a new process and install a child handler to wait for	1599	Example: C<fork()> a new process and install a child handler to wait for
1554	its completion.	1600	its completion.
1555		1601
1556	ev_child cw;	1602	ev_child cw;
1557		1603
1558	static void	1604	static void
1559	child_cb (EV_P_ struct ev_child *w, int revents)	1605	child_cb (EV_P_ struct ev_child *w, int revents)
1560	{	1606	{
1561	ev_child_stop (EV_A_ w);	1607	ev_child_stop (EV_A_ w);
1562	printf ("process %d exited with status %x\n", w->rpid, w->rstatus);	1608	printf ("process %d exited with status %x\n", w->rpid, w->rstatus);
1563	}	1609	}
1564		1610
1565	pid_t pid = fork ();	1611	pid_t pid = fork ();
1566		1612
1567	if (pid < 0)	1613	if (pid < 0)
1568	// error	1614	// error
1569	else if (pid == 0)	1615	else if (pid == 0)
1570	{	1616	{
1571	// the forked child executes here	1617	// the forked child executes here
1572	exit (1);	1618	exit (1);
1573	}	1619	}
1574	else	1620	else
1575	{	1621	{
1576	ev_child_init (&cw, child_cb, pid, 0);	1622	ev_child_init (&cw, child_cb, pid, 0);
1577	ev_child_start (EV_DEFAULT_ &cw);	1623	ev_child_start (EV_DEFAULT_ &cw);
1578	}	1624	}
1579		1625
1580		1626
1581	=head2 C<ev_stat> - did the file attributes just change?	1627	=head2 C<ev_stat> - did the file attributes just change?
1582		1628
1583	This watches a filesystem path for attribute changes. That is, it calls	1629	This watches a file system path for attribute changes. That is, it calls
1584	C<stat> regularly (or when the OS says it changed) and sees if it changed	1630	C<stat> regularly (or when the OS says it changed) and sees if it changed
1585	compared to the last time, invoking the callback if it did.	1631	compared to the last time, invoking the callback if it did.
1586		1632
1587	The path does not need to exist: changing from "path exists" to "path does	1633	The path does not need to exist: changing from "path exists" to "path does
1588	not exist" is a status change like any other. The condition "path does	1634	not exist" is a status change like any other. The condition "path does
…		…
1606	as even with OS-supported change notifications, this can be	1652	as even with OS-supported change notifications, this can be
1607	resource-intensive.	1653	resource-intensive.
1608		1654
1609	At the time of this writing, only the Linux inotify interface is	1655	At the time of this writing, only the Linux inotify interface is
1610	implemented (implementing kqueue support is left as an exercise for the	1656	implemented (implementing kqueue support is left as an exercise for the
		1657	reader, note, however, that the author sees no way of implementing ev_stat
1611	reader). Inotify will be used to give hints only and should not change the	1658	semantics with kqueue). Inotify will be used to give hints only and should
1612	semantics of C<ev_stat> watchers, which means that libev sometimes needs	1659	not change the semantics of C<ev_stat> watchers, which means that libev
1613	to fall back to regular polling again even with inotify, but changes are	1660	sometimes needs to fall back to regular polling again even with inotify,
1614	usually detected immediately, and if the file exists there will be no	1661	but changes are usually detected immediately, and if the file exists there
1615	polling.	1662	will be no polling.
1616		1663
1617	=head3 ABI Issues (Largefile Support)	1664	=head3 ABI Issues (Largefile Support)
1618		1665
1619	Libev by default (unless the user overrides this) uses the default	1666	Libev by default (unless the user overrides this) uses the default
1620	compilation environment, which means that on systems with optionally	1667	compilation environment, which means that on systems with optionally
1621	disabled large file support, you get the 32 bit version of the stat	1668	disabled large file support, you get the 32 bit version of the stat
1622	structure. When using the library from programs that change the ABI to	1669	structure. When using the library from programs that change the ABI to
1623	use 64 bit file offsets the programs will fail. In that case you have to	1670	use 64 bit file offsets the programs will fail. In that case you have to
1624	compile libev with the same flags to get binary compatibility. This is	1671	compile libev with the same flags to get binary compatibility. This is
1625	obviously the case with any flags that change the ABI, but the problem is	1672	obviously the case with any flags that change the ABI, but the problem is
1626	most noticably with ev_stat and largefile support.	1673	most noticeably with ev_stat and large file support.
1627		1674
1628	=head3 Inotify	1675	=head3 Inotify
1629		1676
1630	When C<inotify (7)> support has been compiled into libev (generally only	1677	When C<inotify (7)> support has been compiled into libev (generally only
1631	available on Linux) and present at runtime, it will be used to speed up	1678	available on Linux) and present at runtime, it will be used to speed up
1632	change detection where possible. The inotify descriptor will be created lazily	1679	change detection where possible. The inotify descriptor will be created lazily
1633	when the first C<ev_stat> watcher is being started.	1680	when the first C<ev_stat> watcher is being started.
1634		1681
1635	Inotify presense does not change the semantics of C<ev_stat> watchers	1682	Inotify presence does not change the semantics of C<ev_stat> watchers
1636	except that changes might be detected earlier, and in some cases, to avoid	1683	except that changes might be detected earlier, and in some cases, to avoid
1637	making regular C<stat> calls. Even in the presense of inotify support	1684	making regular C<stat> calls. Even in the presence of inotify support
1638	there are many cases where libev has to resort to regular C<stat> polling.	1685	there are many cases where libev has to resort to regular C<stat> polling.
1639		1686
1640	(There is no support for kqueue, as apparently it cannot be used to	1687	(There is no support for kqueue, as apparently it cannot be used to
1641	implement this functionality, due to the requirement of having a file	1688	implement this functionality, due to the requirement of having a file
1642	descriptor open on the object at all times).	1689	descriptor open on the object at all times).
1643		1690
1644	=head3 The special problem of stat time resolution	1691	=head3 The special problem of stat time resolution
1645		1692
1646	The C<stat ()> syscall only supports full-second resolution portably, and	1693	The C<stat ()> system call only supports full-second resolution portably, and
1647	even on systems where the resolution is higher, many filesystems still	1694	even on systems where the resolution is higher, many file systems still
1648	only support whole seconds.	1695	only support whole seconds.
1649		1696
1650	That means that, if the time is the only thing that changes, you might	1697	That means that, if the time is the only thing that changes, you can
1651	miss updates: on the first update, C<ev_stat> detects a change and calls	1698	easily miss updates: on the first update, C<ev_stat> detects a change and
1652	your callback, which does something. When there is another update within	1699	calls your callback, which does something. When there is another update
1653	the same second, C<ev_stat> will be unable to detect it.	1700	within the same second, C<ev_stat> will be unable to detect it as the stat
		1701	data does not change.
1654		1702
1655	The solution to this is to delay acting on a change for a second (or till	1703	The solution to this is to delay acting on a change for slightly more
1656	the next second boundary), using a roughly one-second delay C<ev_timer>	1704	than a second (or till slightly after the next full second boundary), using
1657	(C<ev_timer_set (w, 0., 1.01); ev_timer_again (loop, w)>). The C<.01>	1705	a roughly one-second-delay C<ev_timer> (e.g. C<ev_timer_set (w, 0., 1.02);
1658	is added to work around small timing inconsistencies of some operating	1706	ev_timer_again (loop, w)>).
1659	systems.	1707
		1708	The C<.02> offset is added to work around small timing inconsistencies
		1709	of some operating systems (where the second counter of the current time
		1710	might be be delayed. One such system is the Linux kernel, where a call to
		1711	C<gettimeofday> might return a timestamp with a full second later than
		1712	a subsequent C<time> call - if the equivalent of C<time ()> is used to
		1713	update file times then there will be a small window where the kernel uses
		1714	the previous second to update file times but libev might already execute
		1715	the timer callback).
1660		1716
1661	=head3 Watcher-Specific Functions and Data Members	1717	=head3 Watcher-Specific Functions and Data Members
1662		1718
1663	=over 4	1719	=over 4
1664		1720
…		…
1670	C<path>. The C<interval> is a hint on how quickly a change is expected to	1726	C<path>. The C<interval> is a hint on how quickly a change is expected to
1671	be detected and should normally be specified as C<0> to let libev choose	1727	be detected and should normally be specified as C<0> to let libev choose
1672	a suitable value. The memory pointed to by C<path> must point to the same	1728	a suitable value. The memory pointed to by C<path> must point to the same
1673	path for as long as the watcher is active.	1729	path for as long as the watcher is active.
1674		1730
1675	The callback will be receive C<EV_STAT> when a change was detected,	1731	The callback will receive C<EV_STAT> when a change was detected, relative
1676	relative to the attributes at the time the watcher was started (or the	1732	to the attributes at the time the watcher was started (or the last change
1677	last change was detected).	1733	was detected).
1678		1734
1679	=item ev_stat_stat (loop, ev_stat *)	1735	=item ev_stat_stat (loop, ev_stat *)
1680		1736
1681	Updates the stat buffer immediately with new values. If you change the	1737	Updates the stat buffer immediately with new values. If you change the
1682	watched path in your callback, you could call this fucntion to avoid	1738	watched path in your callback, you could call this function to avoid
1683	detecting this change (while introducing a race condition). Can also be	1739	detecting this change (while introducing a race condition if you are not
1684	useful simply to find out the new values.	1740	the only one changing the path). Can also be useful simply to find out the
		1741	new values.
1685		1742
1686	=item ev_statdata attr [read-only]	1743	=item ev_statdata attr [read-only]
1687		1744
1688	The most-recently detected attributes of the file. Although the type is of	1745	The most-recently detected attributes of the file. Although the type is
1689	C<ev_statdata>, this is usually the (or one of the) C<struct stat> types	1746	C<ev_statdata>, this is usually the (or one of the) C<struct stat> types
1690	suitable for your system. If the C<st_nlink> member is C<0>, then there	1747	suitable for your system, but you can only rely on the POSIX-standardised
		1748	members to be present. If the C<st_nlink> member is C<0>, then there was
1691	was some error while C<stat>ing the file.	1749	some error while C<stat>ing the file.
1692		1750
1693	=item ev_statdata prev [read-only]	1751	=item ev_statdata prev [read-only]
1694		1752
1695	The previous attributes of the file. The callback gets invoked whenever	1753	The previous attributes of the file. The callback gets invoked whenever
1696	C<prev> != C<attr>.	1754	C<prev> != C<attr>, or, more precisely, one or more of these members
		1755	differ: C<st_dev>, C<st_ino>, C<st_mode>, C<st_nlink>, C<st_uid>,
		1756	C<st_gid>, C<st_rdev>, C<st_size>, C<st_atime>, C<st_mtime>, C<st_ctime>.
1697		1757
1698	=item ev_tstamp interval [read-only]	1758	=item ev_tstamp interval [read-only]
1699		1759
1700	The specified interval.	1760	The specified interval.
1701		1761
1702	=item const char *path [read-only]	1762	=item const char *path [read-only]
1703		1763
1704	The filesystem path that is being watched.	1764	The file system path that is being watched.
1705		1765
1706	=back	1766	=back
1707		1767
1708	=head3 Examples	1768	=head3 Examples
1709		1769
1710	Example: Watch C</etc/passwd> for attribute changes.	1770	Example: Watch C</etc/passwd> for attribute changes.
1711		1771
1712	static void	1772	static void
1713	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)	1773	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
1714	{	1774	{
1715	/* /etc/passwd changed in some way */	1775	/* /etc/passwd changed in some way */
1716	if (w->attr.st_nlink)	1776	if (w->attr.st_nlink)
1717	{	1777	{
1718	printf ("passwd current size %ld\n", (long)w->attr.st_size);	1778	printf ("passwd current size %ld\n", (long)w->attr.st_size);
1719	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);	1779	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
1720	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);	1780	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
1721	}	1781	}
1722	else	1782	else
1723	/* you shalt not abuse printf for puts */	1783	/* you shalt not abuse printf for puts */
1724	puts ("wow, /etc/passwd is not there, expect problems. "	1784	puts ("wow, /etc/passwd is not there, expect problems. "
1725	"if this is windows, they already arrived\n");	1785	"if this is windows, they already arrived\n");
1726	}	1786	}
1727		1787
1728	...	1788	...
1729	ev_stat passwd;	1789	ev_stat passwd;
1730		1790
1731	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);	1791	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);
1732	ev_stat_start (loop, &passwd);	1792	ev_stat_start (loop, &passwd);
1733		1793
1734	Example: Like above, but additionally use a one-second delay so we do not	1794	Example: Like above, but additionally use a one-second delay so we do not
1735	miss updates (however, frequent updates will delay processing, too, so	1795	miss updates (however, frequent updates will delay processing, too, so
1736	one might do the work both on C<ev_stat> callback invocation I<and> on	1796	one might do the work both on C<ev_stat> callback invocation I<and> on
1737	C<ev_timer> callback invocation).	1797	C<ev_timer> callback invocation).
1738		1798
1739	static ev_stat passwd;	1799	static ev_stat passwd;
1740	static ev_timer timer;	1800	static ev_timer timer;
1741		1801
1742	static void	1802	static void
1743	timer_cb (EV_P_ ev_timer *w, int revents)	1803	timer_cb (EV_P_ ev_timer *w, int revents)
1744	{	1804	{
1745	ev_timer_stop (EV_A_ w);	1805	ev_timer_stop (EV_A_ w);
1746		1806
1747	/* now it's one second after the most recent passwd change */	1807	/* now it's one second after the most recent passwd change */
1748	}	1808	}
1749		1809
1750	static void	1810	static void
1751	stat_cb (EV_P_ ev_stat *w, int revents)	1811	stat_cb (EV_P_ ev_stat *w, int revents)
1752	{	1812	{
1753	/* reset the one-second timer */	1813	/* reset the one-second timer */
1754	ev_timer_again (EV_A_ &timer);	1814	ev_timer_again (EV_A_ &timer);
1755	}	1815	}
1756		1816
1757	...	1817	...
1758	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);	1818	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);
1759	ev_stat_start (loop, &passwd);	1819	ev_stat_start (loop, &passwd);
1760	ev_timer_init (&timer, timer_cb, 0., 1.01);	1820	ev_timer_init (&timer, timer_cb, 0., 1.02);
1761		1821
1762		1822
1763	=head2 C<ev_idle> - when you've got nothing better to do...	1823	=head2 C<ev_idle> - when you've got nothing better to do...
1764		1824
1765	Idle watchers trigger events when no other events of the same or higher	1825	Idle watchers trigger events when no other events of the same or higher
…		…
1796	=head3 Examples	1856	=head3 Examples
1797		1857
1798	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the	1858	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1799	callback, free it. Also, use no error checking, as usual.	1859	callback, free it. Also, use no error checking, as usual.
1800		1860
1801	static void	1861	static void
1802	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)	1862	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1803	{	1863	{
1804	free (w);	1864	free (w);
1805	// now do something you wanted to do when the program has	1865	// now do something you wanted to do when the program has
1806	// no longer anything immediate to do.	1866	// no longer anything immediate to do.
1807	}	1867	}
1808		1868
1809	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));	1869	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1810	ev_idle_init (idle_watcher, idle_cb);	1870	ev_idle_init (idle_watcher, idle_cb);
1811	ev_idle_start (loop, idle_cb);	1871	ev_idle_start (loop, idle_cb);
1812		1872
1813		1873
1814	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!	1874	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!
1815		1875
1816	Prepare and check watchers are usually (but not always) used in tandem:	1876	Prepare and check watchers are usually (but not always) used in tandem:
…		…
1835		1895
1836	This is done by examining in each prepare call which file descriptors need	1896	This is done by examining in each prepare call which file descriptors need
1837	to be watched by the other library, registering C<ev_io> watchers for	1897	to be watched by the other library, registering C<ev_io> watchers for
1838	them and starting an C<ev_timer> watcher for any timeouts (many libraries	1898	them and starting an C<ev_timer> watcher for any timeouts (many libraries
1839	provide just this functionality). Then, in the check watcher you check for	1899	provide just this functionality). Then, in the check watcher you check for
1840	any events that occured (by checking the pending status of all watchers	1900	any events that occurred (by checking the pending status of all watchers
1841	and stopping them) and call back into the library. The I/O and timer	1901	and stopping them) and call back into the library. The I/O and timer
1842	callbacks will never actually be called (but must be valid nevertheless,	1902	callbacks will never actually be called (but must be valid nevertheless,
1843	because you never know, you know?).	1903	because you never know, you know?).
1844		1904
1845	As another example, the Perl Coro module uses these hooks to integrate	1905	As another example, the Perl Coro module uses these hooks to integrate
…		…
1853		1913
1854	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)	1914	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)
1855	priority, to ensure that they are being run before any other watchers	1915	priority, to ensure that they are being run before any other watchers
1856	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,	1916	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,
1857	too) should not activate ("feed") events into libev. While libev fully	1917	too) should not activate ("feed") events into libev. While libev fully
1858	supports this, they will be called before other C<ev_check> watchers	1918	supports this, they might get executed before other C<ev_check> watchers
1859	did their job. As C<ev_check> watchers are often used to embed other	1919	did their job. As C<ev_check> watchers are often used to embed other
1860	(non-libev) event loops those other event loops might be in an unusable	1920	(non-libev) event loops those other event loops might be in an unusable
1861	state until their C<ev_check> watcher ran (always remind yourself to	1921	state until their C<ev_check> watcher ran (always remind yourself to
1862	coexist peacefully with others).	1922	coexist peacefully with others).
1863		1923
…		…
1878	=head3 Examples	1938	=head3 Examples
1879		1939
1880	There are a number of principal ways to embed other event loops or modules	1940	There are a number of principal ways to embed other event loops or modules
1881	into libev. Here are some ideas on how to include libadns into libev	1941	into libev. Here are some ideas on how to include libadns into libev
1882	(there is a Perl module named C<EV::ADNS> that does this, which you could	1942	(there is a Perl module named C<EV::ADNS> that does this, which you could
1883	use for an actually working example. Another Perl module named C<EV::Glib>	1943	use as a working example. Another Perl module named C<EV::Glib> embeds a
1884	embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV	1944	Glib main context into libev, and finally, C<Glib::EV> embeds EV into the
1885	into the Glib event loop).	1945	Glib event loop).
1886		1946
1887	Method 1: Add IO watchers and a timeout watcher in a prepare handler,	1947	Method 1: Add IO watchers and a timeout watcher in a prepare handler,
1888	and in a check watcher, destroy them and call into libadns. What follows	1948	and in a check watcher, destroy them and call into libadns. What follows
1889	is pseudo-code only of course. This requires you to either use a low	1949	is pseudo-code only of course. This requires you to either use a low
1890	priority for the check watcher or use C<ev_clear_pending> explicitly, as	1950	priority for the check watcher or use C<ev_clear_pending> explicitly, as
1891	the callbacks for the IO/timeout watchers might not have been called yet.	1951	the callbacks for the IO/timeout watchers might not have been called yet.
1892		1952
1893	static ev_io iow [nfd];	1953	static ev_io iow [nfd];
1894	static ev_timer tw;	1954	static ev_timer tw;
1895		1955
1896	static void	1956	static void
1897	io_cb (ev_loop *loop, ev_io *w, int revents)	1957	io_cb (ev_loop *loop, ev_io *w, int revents)
1898	{	1958	{
1899	}	1959	}
1900		1960
1901	// create io watchers for each fd and a timer before blocking	1961	// create io watchers for each fd and a timer before blocking
1902	static void	1962	static void
1903	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)	1963	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1904	{	1964	{
1905	int timeout = 3600000;	1965	int timeout = 3600000;
1906	struct pollfd fds [nfd];	1966	struct pollfd fds [nfd];
1907	// actual code will need to loop here and realloc etc.	1967	// actual code will need to loop here and realloc etc.
1908	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1968	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1909		1969
1910	/* the callback is illegal, but won't be called as we stop during check */	1970	/* the callback is illegal, but won't be called as we stop during check */
1911	ev_timer_init (&tw, 0, timeout * 1e-3);	1971	ev_timer_init (&tw, 0, timeout * 1e-3);
1912	ev_timer_start (loop, &tw);	1972	ev_timer_start (loop, &tw);
1913		1973
1914	// create one ev_io per pollfd	1974	// create one ev_io per pollfd
1915	for (int i = 0; i < nfd; ++i)	1975	for (int i = 0; i < nfd; ++i)
1916	{	1976	{
1917	ev_io_init (iow + i, io_cb, fds [i].fd,	1977	ev_io_init (iow + i, io_cb, fds [i].fd,
1918	((fds [i].events & POLLIN ? EV_READ : 0)	1978	((fds [i].events & POLLIN ? EV_READ : 0)
1919	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	1979	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1920		1980
1921	fds [i].revents = 0;	1981	fds [i].revents = 0;
1922	ev_io_start (loop, iow + i);	1982	ev_io_start (loop, iow + i);
1923	}	1983	}
1924	}	1984	}
1925		1985
1926	// stop all watchers after blocking	1986	// stop all watchers after blocking
1927	static void	1987	static void
1928	adns_check_cb (ev_loop *loop, ev_check *w, int revents)	1988	adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1929	{	1989	{
1930	ev_timer_stop (loop, &tw);	1990	ev_timer_stop (loop, &tw);
1931		1991
1932	for (int i = 0; i < nfd; ++i)	1992	for (int i = 0; i < nfd; ++i)
1933	{	1993	{
1934	// set the relevant poll flags	1994	// set the relevant poll flags
1935	// could also call adns_processreadable etc. here	1995	// could also call adns_processreadable etc. here
1936	struct pollfd *fd = fds + i;	1996	struct pollfd *fd = fds + i;
1937	int revents = ev_clear_pending (iow + i);	1997	int revents = ev_clear_pending (iow + i);
1938	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;	1998	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1939	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;	1999	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1940		2000
1941	// now stop the watcher	2001	// now stop the watcher
1942	ev_io_stop (loop, iow + i);	2002	ev_io_stop (loop, iow + i);
1943	}	2003	}
1944		2004
1945	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	2005	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
1946	}	2006	}
1947		2007
1948	Method 2: This would be just like method 1, but you run C<adns_afterpoll>	2008	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
1949	in the prepare watcher and would dispose of the check watcher.	2009	in the prepare watcher and would dispose of the check watcher.
1950		2010
1951	Method 3: If the module to be embedded supports explicit event	2011	Method 3: If the module to be embedded supports explicit event
1952	notification (adns does), you can also make use of the actual watcher	2012	notification (libadns does), you can also make use of the actual watcher
1953	callbacks, and only destroy/create the watchers in the prepare watcher.	2013	callbacks, and only destroy/create the watchers in the prepare watcher.
1954		2014
1955	static void	2015	static void
1956	timer_cb (EV_P_ ev_timer *w, int revents)	2016	timer_cb (EV_P_ ev_timer *w, int revents)
1957	{	2017	{
1958	adns_state ads = (adns_state)w->data;	2018	adns_state ads = (adns_state)w->data;
1959	update_now (EV_A);	2019	update_now (EV_A);
1960		2020
1961	adns_processtimeouts (ads, &tv_now);	2021	adns_processtimeouts (ads, &tv_now);
1962	}	2022	}
1963		2023
1964	static void	2024	static void
1965	io_cb (EV_P_ ev_io *w, int revents)	2025	io_cb (EV_P_ ev_io *w, int revents)
1966	{	2026	{
1967	adns_state ads = (adns_state)w->data;	2027	adns_state ads = (adns_state)w->data;
1968	update_now (EV_A);	2028	update_now (EV_A);
1969		2029
1970	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);	2030	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
1971	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);	2031	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
1972	}	2032	}
1973		2033
1974	// do not ever call adns_afterpoll	2034	// do not ever call adns_afterpoll
1975		2035
1976	Method 4: Do not use a prepare or check watcher because the module you	2036	Method 4: Do not use a prepare or check watcher because the module you
1977	want to embed is too inflexible to support it. Instead, youc na override	2037	want to embed is too inflexible to support it. Instead, you can override
1978	their poll function. The drawback with this solution is that the main	2038	their poll function. The drawback with this solution is that the main
1979	loop is now no longer controllable by EV. The C<Glib::EV> module does	2039	loop is now no longer controllable by EV. The C<Glib::EV> module does
1980	this.	2040	this.
1981		2041
1982	static gint	2042	static gint
1983	event_poll_func (GPollFD *fds, guint nfds, gint timeout)	2043	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
1984	{	2044	{
1985	int got_events = 0;	2045	int got_events = 0;
1986		2046
1987	for (n = 0; n < nfds; ++n)	2047	for (n = 0; n < nfds; ++n)
1988	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events	2048	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
1989		2049
1990	if (timeout >= 0)	2050	if (timeout >= 0)
1991	// create/start timer	2051	// create/start timer
1992		2052
1993	// poll	2053	// poll
1994	ev_loop (EV_A_ 0);	2054	ev_loop (EV_A_ 0);
1995		2055
1996	// stop timer again	2056	// stop timer again
1997	if (timeout >= 0)	2057	if (timeout >= 0)
1998	ev_timer_stop (EV_A_ &to);	2058	ev_timer_stop (EV_A_ &to);
1999		2059
2000	// stop io watchers again - their callbacks should have set	2060	// stop io watchers again - their callbacks should have set
2001	for (n = 0; n < nfds; ++n)	2061	for (n = 0; n < nfds; ++n)
2002	ev_io_stop (EV_A_ iow [n]);	2062	ev_io_stop (EV_A_ iow [n]);
2003		2063
2004	return got_events;	2064	return got_events;
2005	}	2065	}
2006		2066
2007		2067
2008	=head2 C<ev_embed> - when one backend isn't enough...	2068	=head2 C<ev_embed> - when one backend isn't enough...
2009		2069
2010	This is a rather advanced watcher type that lets you embed one event loop	2070	This is a rather advanced watcher type that lets you embed one event loop
…		…
2066		2126
2067	Configures the watcher to embed the given loop, which must be	2127	Configures the watcher to embed the given loop, which must be
2068	embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be	2128	embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be
2069	invoked automatically, otherwise it is the responsibility of the callback	2129	invoked automatically, otherwise it is the responsibility of the callback
2070	to invoke it (it will continue to be called until the sweep has been done,	2130	to invoke it (it will continue to be called until the sweep has been done,
2071	if you do not want thta, you need to temporarily stop the embed watcher).	2131	if you do not want that, you need to temporarily stop the embed watcher).
2072		2132
2073	=item ev_embed_sweep (loop, ev_embed *)	2133	=item ev_embed_sweep (loop, ev_embed *)
2074		2134
2075	Make a single, non-blocking sweep over the embedded loop. This works	2135	Make a single, non-blocking sweep over the embedded loop. This works
2076	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most	2136	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
2077	apropriate way for embedded loops.	2137	appropriate way for embedded loops.
2078		2138
2079	=item struct ev_loop *other [read-only]	2139	=item struct ev_loop *other [read-only]
2080		2140
2081	The embedded event loop.	2141	The embedded event loop.
2082		2142
…		…
2084		2144
2085	=head3 Examples	2145	=head3 Examples
2086		2146
2087	Example: Try to get an embeddable event loop and embed it into the default	2147	Example: Try to get an embeddable event loop and embed it into the default
2088	event loop. If that is not possible, use the default loop. The default	2148	event loop. If that is not possible, use the default loop. The default
2089	loop is stored in C<loop_hi>, while the mebeddable loop is stored in	2149	loop is stored in C<loop_hi>, while the embeddable loop is stored in
2090	C<loop_lo> (which is C<loop_hi> in the acse no embeddable loop can be	2150	C<loop_lo> (which is C<loop_hi> in the case no embeddable loop can be
2091	used).	2151	used).
2092		2152
2093	struct ev_loop *loop_hi = ev_default_init (0);	2153	struct ev_loop *loop_hi = ev_default_init (0);
2094	struct ev_loop *loop_lo = 0;	2154	struct ev_loop *loop_lo = 0;
2095	struct ev_embed embed;	2155	struct ev_embed embed;
2096		2156
2097	// see if there is a chance of getting one that works	2157	// see if there is a chance of getting one that works
2098	// (remember that a flags value of 0 means autodetection)	2158	// (remember that a flags value of 0 means autodetection)
2099	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()	2159	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()
2100	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())	2160	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())
2101	: 0;	2161	: 0;
2102		2162
2103	// if we got one, then embed it, otherwise default to loop_hi	2163	// if we got one, then embed it, otherwise default to loop_hi
2104	if (loop_lo)	2164	if (loop_lo)
2105	{	2165	{
2106	ev_embed_init (&embed, 0, loop_lo);	2166	ev_embed_init (&embed, 0, loop_lo);
2107	ev_embed_start (loop_hi, &embed);	2167	ev_embed_start (loop_hi, &embed);
2108	}	2168	}
2109	else	2169	else
2110	loop_lo = loop_hi;	2170	loop_lo = loop_hi;
2111		2171
2112	Example: Check if kqueue is available but not recommended and create	2172	Example: Check if kqueue is available but not recommended and create
2113	a kqueue backend for use with sockets (which usually work with any	2173	a kqueue backend for use with sockets (which usually work with any
2114	kqueue implementation). Store the kqueue/socket-only event loop in	2174	kqueue implementation). Store the kqueue/socket-only event loop in
2115	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).	2175	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).
2116		2176
2117	struct ev_loop *loop = ev_default_init (0);	2177	struct ev_loop *loop = ev_default_init (0);
2118	struct ev_loop *loop_socket = 0;	2178	struct ev_loop *loop_socket = 0;
2119	struct ev_embed embed;	2179	struct ev_embed embed;
2120		2180
2121	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)	2181	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)
2122	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))	2182	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))
2123	{	2183	{
2124	ev_embed_init (&embed, 0, loop_socket);	2184	ev_embed_init (&embed, 0, loop_socket);
2125	ev_embed_start (loop, &embed);	2185	ev_embed_start (loop, &embed);
2126	}	2186	}
2127		2187
2128	if (!loop_socket)	2188	if (!loop_socket)
2129	loop_socket = loop;	2189	loop_socket = loop;
2130		2190
2131	// now use loop_socket for all sockets, and loop for everything else	2191	// now use loop_socket for all sockets, and loop for everything else
2132		2192
2133		2193
2134	=head2 C<ev_fork> - the audacity to resume the event loop after a fork	2194	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
2135		2195
2136	Fork watchers are called when a C<fork ()> was detected (usually because	2196	Fork watchers are called when a C<fork ()> was detected (usually because
…		…
2189		2249
2190	=item queueing from a signal handler context	2250	=item queueing from a signal handler context
2191		2251
2192	To implement race-free queueing, you simply add to the queue in the signal	2252	To implement race-free queueing, you simply add to the queue in the signal
2193	handler but you block the signal handler in the watcher callback. Here is an example that does that for	2253	handler but you block the signal handler in the watcher callback. Here is an example that does that for
2194	some fictitiuous SIGUSR1 handler:	2254	some fictitious SIGUSR1 handler:
2195		2255
2196	static ev_async mysig;	2256	static ev_async mysig;
2197		2257
2198	static void	2258	static void
2199	sigusr1_handler (void)	2259	sigusr1_handler (void)
…		…
2273	=item ev_async_send (loop, ev_async *)	2333	=item ev_async_send (loop, ev_async *)
2274		2334
2275	Sends/signals/activates the given C<ev_async> watcher, that is, feeds	2335	Sends/signals/activates the given C<ev_async> watcher, that is, feeds
2276	an C<EV_ASYNC> event on the watcher into the event loop. Unlike	2336	an C<EV_ASYNC> event on the watcher into the event loop. Unlike
2277	C<ev_feed_event>, this call is safe to do in other threads, signal or	2337	C<ev_feed_event>, this call is safe to do in other threads, signal or
2278	similar contexts (see the dicusssion of C<EV_ATOMIC_T> in the embedding	2338	similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding
2279	section below on what exactly this means).	2339	section below on what exactly this means).
2280		2340
2281	This call incurs the overhead of a syscall only once per loop iteration,	2341	This call incurs the overhead of a system call only once per loop iteration,
2282	so while the overhead might be noticable, it doesn't apply to repeated	2342	so while the overhead might be noticeable, it doesn't apply to repeated
2283	calls to C<ev_async_send>.	2343	calls to C<ev_async_send>.
		2344
		2345	=item bool = ev_async_pending (ev_async *)
		2346
		2347	Returns a non-zero value when C<ev_async_send> has been called on the
		2348	watcher but the event has not yet been processed (or even noted) by the
		2349	event loop.
		2350
		2351	C<ev_async_send> sets a flag in the watcher and wakes up the loop. When
		2352	the loop iterates next and checks for the watcher to have become active,
		2353	it will reset the flag again. C<ev_async_pending> can be used to very
		2354	quickly check whether invoking the loop might be a good idea.
		2355
		2356	Not that this does I<not> check whether the watcher itself is pending, only
		2357	whether it has been requested to make this watcher pending.
2284		2358
2285	=back	2359	=back
2286		2360
2287		2361
2288	=head1 OTHER FUNCTIONS	2362	=head1 OTHER FUNCTIONS
…		…
2299	or timeout without having to allocate/configure/start/stop/free one or	2373	or timeout without having to allocate/configure/start/stop/free one or
2300	more watchers yourself.	2374	more watchers yourself.
2301		2375
2302	If C<fd> is less than 0, then no I/O watcher will be started and events	2376	If C<fd> is less than 0, then no I/O watcher will be started and events
2303	is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and	2377	is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and
2304	C<events> set will be craeted and started.	2378	C<events> set will be created and started.
2305		2379
2306	If C<timeout> is less than 0, then no timeout watcher will be	2380	If C<timeout> is less than 0, then no timeout watcher will be
2307	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and	2381	started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and
2308	repeat = 0) will be started. While C<0> is a valid timeout, it is of	2382	repeat = 0) will be started. While C<0> is a valid timeout, it is of
2309	dubious value.	2383	dubious value.
…		…
2311	The callback has the type C<void (*cb)(int revents, void *arg)> and gets	2385	The callback has the type C<void (*cb)(int revents, void *arg)> and gets
2312	passed an C<revents> set like normal event callbacks (a combination of	2386	passed an C<revents> set like normal event callbacks (a combination of
2313	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>	2387	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>
2314	value passed to C<ev_once>:	2388	value passed to C<ev_once>:
2315		2389
2316	static void stdin_ready (int revents, void *arg)	2390	static void stdin_ready (int revents, void *arg)
2317	{	2391	{
2318	if (revents & EV_TIMEOUT)	2392	if (revents & EV_TIMEOUT)
2319	/* doh, nothing entered */;	2393	/* doh, nothing entered */;
2320	else if (revents & EV_READ)	2394	else if (revents & EV_READ)
2321	/* stdin might have data for us, joy! */;	2395	/* stdin might have data for us, joy! */;
2322	}	2396	}
2323		2397
2324	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	2398	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
2325		2399
2326	=item ev_feed_event (ev_loop *, watcher *, int revents)	2400	=item ev_feed_event (ev_loop *, watcher *, int revents)
2327		2401
2328	Feeds the given event set into the event loop, as if the specified event	2402	Feeds the given event set into the event loop, as if the specified event
2329	had happened for the specified watcher (which must be a pointer to an	2403	had happened for the specified watcher (which must be a pointer to an
…		…
2334	Feed an event on the given fd, as if a file descriptor backend detected	2408	Feed an event on the given fd, as if a file descriptor backend detected
2335	the given events it.	2409	the given events it.
2336		2410
2337	=item ev_feed_signal_event (ev_loop *loop, int signum)	2411	=item ev_feed_signal_event (ev_loop *loop, int signum)
2338		2412
2339	Feed an event as if the given signal occured (C<loop> must be the default	2413	Feed an event as if the given signal occurred (C<loop> must be the default
2340	loop!).	2414	loop!).
2341		2415
2342	=back	2416	=back
2343		2417
2344		2418
…		…
2360		2434
2361	=item * Priorities are not currently supported. Initialising priorities	2435	=item * Priorities are not currently supported. Initialising priorities
2362	will fail and all watchers will have the same priority, even though there	2436	will fail and all watchers will have the same priority, even though there
2363	is an ev_pri field.	2437	is an ev_pri field.
2364		2438
		2439	=item * In libevent, the last base created gets the signals, in libev, the
		2440	first base created (== the default loop) gets the signals.
		2441
2365	=item * Other members are not supported.	2442	=item * Other members are not supported.
2366		2443
2367	=item * The libev emulation is I<not> ABI compatible to libevent, you need	2444	=item * The libev emulation is I<not> ABI compatible to libevent, you need
2368	to use the libev header file and library.	2445	to use the libev header file and library.
2369		2446
2370	=back	2447	=back
2371		2448
2372	=head1 C++ SUPPORT	2449	=head1 C++ SUPPORT
2373		2450
2374	Libev comes with some simplistic wrapper classes for C++ that mainly allow	2451	Libev comes with some simplistic wrapper classes for C++ that mainly allow
2375	you to use some convinience methods to start/stop watchers and also change	2452	you to use some convenience methods to start/stop watchers and also change
2376	the callback model to a model using method callbacks on objects.	2453	the callback model to a model using method callbacks on objects.
2377		2454
2378	To use it,	2455	To use it,
2379		2456
2380	#include <ev++.h>	2457	#include <ev++.h>
2381		2458
2382	This automatically includes F<ev.h> and puts all of its definitions (many	2459	This automatically includes F<ev.h> and puts all of its definitions (many
2383	of them macros) into the global namespace. All C++ specific things are	2460	of them macros) into the global namespace. All C++ specific things are
2384	put into the C<ev> namespace. It should support all the same embedding	2461	put into the C<ev> namespace. It should support all the same embedding
2385	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.	2462	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
…		…
2452	your compiler is good :), then the method will be fully inlined into the	2529	your compiler is good :), then the method will be fully inlined into the
2453	thunking function, making it as fast as a direct C callback.	2530	thunking function, making it as fast as a direct C callback.
2454		2531
2455	Example: simple class declaration and watcher initialisation	2532	Example: simple class declaration and watcher initialisation
2456		2533
2457	struct myclass	2534	struct myclass
2458	{	2535	{
2459	void io_cb (ev::io &w, int revents) { }	2536	void io_cb (ev::io &w, int revents) { }
2460	}	2537	}
2461		2538
2462	myclass obj;	2539	myclass obj;
2463	ev::io iow;	2540	ev::io iow;
2464	iow.set <myclass, &myclass::io_cb> (&obj);	2541	iow.set <myclass, &myclass::io_cb> (&obj);
2465		2542
2466	=item w->set<function> (void *data = 0)	2543	=item w->set<function> (void *data = 0)
2467		2544
2468	Also sets a callback, but uses a static method or plain function as	2545	Also sets a callback, but uses a static method or plain function as
2469	callback. The optional C<data> argument will be stored in the watcher's	2546	callback. The optional C<data> argument will be stored in the watcher's
…		…
2473		2550
2474	See the method-C<set> above for more details.	2551	See the method-C<set> above for more details.
2475		2552
2476	Example:	2553	Example:
2477		2554
2478	static void io_cb (ev::io &w, int revents) { }	2555	static void io_cb (ev::io &w, int revents) { }
2479	iow.set <io_cb> ();	2556	iow.set <io_cb> ();
2480		2557
2481	=item w->set (struct ev_loop *)	2558	=item w->set (struct ev_loop *)
2482		2559
2483	Associates a different C<struct ev_loop> with this watcher. You can only	2560	Associates a different C<struct ev_loop> with this watcher. You can only
2484	do this when the watcher is inactive (and not pending either).	2561	do this when the watcher is inactive (and not pending either).
2485		2562
2486	=item w->set ([args])	2563	=item w->set ([arguments])
2487		2564
2488	Basically the same as C<ev_TYPE_set>, with the same args. Must be	2565	Basically the same as C<ev_TYPE_set>, with the same arguments. Must be
2489	called at least once. Unlike the C counterpart, an active watcher gets	2566	called at least once. Unlike the C counterpart, an active watcher gets
2490	automatically stopped and restarted when reconfiguring it with this	2567	automatically stopped and restarted when reconfiguring it with this
2491	method.	2568	method.
2492		2569
2493	=item w->start ()	2570	=item w->start ()
…		…
2517	=back	2594	=back
2518		2595
2519	Example: Define a class with an IO and idle watcher, start one of them in	2596	Example: Define a class with an IO and idle watcher, start one of them in
2520	the constructor.	2597	the constructor.
2521		2598
2522	class myclass	2599	class myclass
2523	{	2600	{
2524	ev::io io; void io_cb (ev::io &w, int revents);	2601	ev::io io; void io_cb (ev::io &w, int revents);
2525	ev:idle idle void idle_cb (ev::idle &w, int revents);	2602	ev:idle idle void idle_cb (ev::idle &w, int revents);
2526		2603
2527	myclass (int fd)	2604	myclass (int fd)
2528	{	2605	{
2529	io .set <myclass, &myclass::io_cb > (this);	2606	io .set <myclass, &myclass::io_cb > (this);
2530	idle.set <myclass, &myclass::idle_cb> (this);	2607	idle.set <myclass, &myclass::idle_cb> (this);
2531		2608
2532	io.start (fd, ev::READ);	2609	io.start (fd, ev::READ);
2533	}	2610	}
2534	};	2611	};
2535		2612
2536		2613
2537	=head1 OTHER LANGUAGE BINDINGS	2614	=head1 OTHER LANGUAGE BINDINGS
2538		2615
2539	Libev does not offer other language bindings itself, but bindings for a	2616	Libev does not offer other language bindings itself, but bindings for a
2540	numbe rof languages exist in the form of third-party packages. If you know	2617	number of languages exist in the form of third-party packages. If you know
2541	any interesting language binding in addition to the ones listed here, drop	2618	any interesting language binding in addition to the ones listed here, drop
2542	me a note.	2619	me a note.
2543		2620
2544	=over 4	2621	=over 4
2545		2622
…		…
2549	libev. EV is developed together with libev. Apart from the EV core module,	2626	libev. EV is developed together with libev. Apart from the EV core module,
2550	there are additional modules that implement libev-compatible interfaces	2627	there are additional modules that implement libev-compatible interfaces
2551	to C<libadns> (C<EV::ADNS>), C<Net::SNMP> (C<Net::SNMP::EV>) and the	2628	to C<libadns> (C<EV::ADNS>), C<Net::SNMP> (C<Net::SNMP::EV>) and the
2552	C<libglib> event core (C<Glib::EV> and C<EV::Glib>).	2629	C<libglib> event core (C<Glib::EV> and C<EV::Glib>).
2553		2630
2554	It can be found and installed via CPAN, its homepage is found at	2631	It can be found and installed via CPAN, its homepage is at
2555	L<http://software.schmorp.de/pkg/EV>.	2632	L<http://software.schmorp.de/pkg/EV>.
2556		2633
		2634	=item Python
		2635
		2636	Python bindings can be found at L<http://code.google.com/p/pyev/>. It
		2637	seems to be quite complete and well-documented. Note, however, that the
		2638	patch they require for libev is outright dangerous as it breaks the ABI
		2639	for everybody else, and therefore, should never be applied in an installed
		2640	libev (if python requires an incompatible ABI then it needs to embed
		2641	libev).
		2642
2557	=item Ruby	2643	=item Ruby
2558		2644
2559	Tony Arcieri has written a ruby extension that offers access to a subset	2645	Tony Arcieri has written a ruby extension that offers access to a subset
2560	of the libev API and adds filehandle abstractions, asynchronous DNS and	2646	of the libev API and adds file handle abstractions, asynchronous DNS and
2561	more on top of it. It can be found via gem servers. Its homepage is at	2647	more on top of it. It can be found via gem servers. Its homepage is at
2562	L<http://rev.rubyforge.org/>.	2648	L<http://rev.rubyforge.org/>.
2563		2649
2564	=item D	2650	=item D
2565		2651
…		…
2569	=back	2655	=back
2570		2656
2571		2657
2572	=head1 MACRO MAGIC	2658	=head1 MACRO MAGIC
2573		2659
2574	Libev can be compiled with a variety of options, the most fundamantal	2660	Libev can be compiled with a variety of options, the most fundamental
2575	of which is C<EV_MULTIPLICITY>. This option determines whether (most)	2661	of which is C<EV_MULTIPLICITY>. This option determines whether (most)
2576	functions and callbacks have an initial C<struct ev_loop *> argument.	2662	functions and callbacks have an initial C<struct ev_loop *> argument.
2577		2663
2578	To make it easier to write programs that cope with either variant, the	2664	To make it easier to write programs that cope with either variant, the
2579	following macros are defined:	2665	following macros are defined:
…		…
2584		2670
2585	This provides the loop I<argument> for functions, if one is required ("ev	2671	This provides the loop I<argument> for functions, if one is required ("ev
2586	loop argument"). The C<EV_A> form is used when this is the sole argument,	2672	loop argument"). The C<EV_A> form is used when this is the sole argument,
2587	C<EV_A_> is used when other arguments are following. Example:	2673	C<EV_A_> is used when other arguments are following. Example:
2588		2674
2589	ev_unref (EV_A);	2675	ev_unref (EV_A);
2590	ev_timer_add (EV_A_ watcher);	2676	ev_timer_add (EV_A_ watcher);
2591	ev_loop (EV_A_ 0);	2677	ev_loop (EV_A_ 0);
2592		2678
2593	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	2679	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
2594	which is often provided by the following macro.	2680	which is often provided by the following macro.
2595		2681
2596	=item C<EV_P>, C<EV_P_>	2682	=item C<EV_P>, C<EV_P_>
2597		2683
2598	This provides the loop I<parameter> for functions, if one is required ("ev	2684	This provides the loop I<parameter> for functions, if one is required ("ev
2599	loop parameter"). The C<EV_P> form is used when this is the sole parameter,	2685	loop parameter"). The C<EV_P> form is used when this is the sole parameter,
2600	C<EV_P_> is used when other parameters are following. Example:	2686	C<EV_P_> is used when other parameters are following. Example:
2601		2687
2602	// this is how ev_unref is being declared	2688	// this is how ev_unref is being declared
2603	static void ev_unref (EV_P);	2689	static void ev_unref (EV_P);
2604		2690
2605	// this is how you can declare your typical callback	2691	// this is how you can declare your typical callback
2606	static void cb (EV_P_ ev_timer *w, int revents)	2692	static void cb (EV_P_ ev_timer *w, int revents)
2607		2693
2608	It declares a parameter C<loop> of type C<struct ev_loop *>, quite	2694	It declares a parameter C<loop> of type C<struct ev_loop *>, quite
2609	suitable for use with C<EV_A>.	2695	suitable for use with C<EV_A>.
2610		2696
2611	=item C<EV_DEFAULT>, C<EV_DEFAULT_>	2697	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
2612		2698
2613	Similar to the other two macros, this gives you the value of the default	2699	Similar to the other two macros, this gives you the value of the default
2614	loop, if multiple loops are supported ("ev loop default").	2700	loop, if multiple loops are supported ("ev loop default").
		2701
		2702	=item C<EV_DEFAULT_UC>, C<EV_DEFAULT_UC_>
		2703
		2704	Usage identical to C<EV_DEFAULT> and C<EV_DEFAULT_>, but requires that the
		2705	default loop has been initialised (C<UC> == unchecked). Their behaviour
		2706	is undefined when the default loop has not been initialised by a previous
		2707	execution of C<EV_DEFAULT>, C<EV_DEFAULT_> or C<ev_default_init (...)>.
		2708
		2709	It is often prudent to use C<EV_DEFAULT> when initialising the first
		2710	watcher in a function but use C<EV_DEFAULT_UC> afterwards.
2615		2711
2616	=back	2712	=back
2617		2713
2618	Example: Declare and initialise a check watcher, utilising the above	2714	Example: Declare and initialise a check watcher, utilising the above
2619	macros so it will work regardless of whether multiple loops are supported	2715	macros so it will work regardless of whether multiple loops are supported
2620	or not.	2716	or not.
2621		2717
2622	static void	2718	static void
2623	check_cb (EV_P_ ev_timer *w, int revents)	2719	check_cb (EV_P_ ev_timer *w, int revents)
2624	{	2720	{
2625	ev_check_stop (EV_A_ w);	2721	ev_check_stop (EV_A_ w);
2626	}	2722	}
2627		2723
2628	ev_check check;	2724	ev_check check;
2629	ev_check_init (&check, check_cb);	2725	ev_check_init (&check, check_cb);
2630	ev_check_start (EV_DEFAULT_ &check);	2726	ev_check_start (EV_DEFAULT_ &check);
2631	ev_loop (EV_DEFAULT_ 0);	2727	ev_loop (EV_DEFAULT_ 0);
2632		2728
2633	=head1 EMBEDDING	2729	=head1 EMBEDDING
2634		2730
2635	Libev can (and often is) directly embedded into host	2731	Libev can (and often is) directly embedded into host
2636	applications. Examples of applications that embed it include the Deliantra	2732	applications. Examples of applications that embed it include the Deliantra
…		…
2643	libev somewhere in your source tree).	2739	libev somewhere in your source tree).
2644		2740
2645	=head2 FILESETS	2741	=head2 FILESETS
2646		2742
2647	Depending on what features you need you need to include one or more sets of files	2743	Depending on what features you need you need to include one or more sets of files
2648	in your app.	2744	in your application.
2649		2745
2650	=head3 CORE EVENT LOOP	2746	=head3 CORE EVENT LOOP
2651		2747
2652	To include only the libev core (all the C<ev_*> functions), with manual	2748	To include only the libev core (all the C<ev_*> functions), with manual
2653	configuration (no autoconf):	2749	configuration (no autoconf):
2654		2750
2655	#define EV_STANDALONE 1	2751	#define EV_STANDALONE 1
2656	#include "ev.c"	2752	#include "ev.c"
2657		2753
2658	This will automatically include F<ev.h>, too, and should be done in a	2754	This will automatically include F<ev.h>, too, and should be done in a
2659	single C source file only to provide the function implementations. To use	2755	single C source file only to provide the function implementations. To use
2660	it, do the same for F<ev.h> in all files wishing to use this API (best	2756	it, do the same for F<ev.h> in all files wishing to use this API (best
2661	done by writing a wrapper around F<ev.h> that you can include instead and	2757	done by writing a wrapper around F<ev.h> that you can include instead and
2662	where you can put other configuration options):	2758	where you can put other configuration options):
2663		2759
2664	#define EV_STANDALONE 1	2760	#define EV_STANDALONE 1
2665	#include "ev.h"	2761	#include "ev.h"
2666		2762
2667	Both header files and implementation files can be compiled with a C++	2763	Both header files and implementation files can be compiled with a C++
2668	compiler (at least, thats a stated goal, and breakage will be treated	2764	compiler (at least, thats a stated goal, and breakage will be treated
2669	as a bug).	2765	as a bug).
2670		2766
2671	You need the following files in your source tree, or in a directory	2767	You need the following files in your source tree, or in a directory
2672	in your include path (e.g. in libev/ when using -Ilibev):	2768	in your include path (e.g. in libev/ when using -Ilibev):
2673		2769
2674	ev.h	2770	ev.h
2675	ev.c	2771	ev.c
2676	ev_vars.h	2772	ev_vars.h
2677	ev_wrap.h	2773	ev_wrap.h
2678		2774
2679	ev_win32.c required on win32 platforms only	2775	ev_win32.c required on win32 platforms only
2680		2776
2681	ev_select.c only when select backend is enabled (which is enabled by default)	2777	ev_select.c only when select backend is enabled (which is enabled by default)
2682	ev_poll.c only when poll backend is enabled (disabled by default)	2778	ev_poll.c only when poll backend is enabled (disabled by default)
2683	ev_epoll.c only when the epoll backend is enabled (disabled by default)	2779	ev_epoll.c only when the epoll backend is enabled (disabled by default)
2684	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	2780	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
2685	ev_port.c only when the solaris port backend is enabled (disabled by default)	2781	ev_port.c only when the solaris port backend is enabled (disabled by default)
2686		2782
2687	F<ev.c> includes the backend files directly when enabled, so you only need	2783	F<ev.c> includes the backend files directly when enabled, so you only need
2688	to compile this single file.	2784	to compile this single file.
2689		2785
2690	=head3 LIBEVENT COMPATIBILITY API	2786	=head3 LIBEVENT COMPATIBILITY API
2691		2787
2692	To include the libevent compatibility API, also include:	2788	To include the libevent compatibility API, also include:
2693		2789
2694	#include "event.c"	2790	#include "event.c"
2695		2791
2696	in the file including F<ev.c>, and:	2792	in the file including F<ev.c>, and:
2697		2793
2698	#include "event.h"	2794	#include "event.h"
2699		2795
2700	in the files that want to use the libevent API. This also includes F<ev.h>.	2796	in the files that want to use the libevent API. This also includes F<ev.h>.
2701		2797
2702	You need the following additional files for this:	2798	You need the following additional files for this:
2703		2799
2704	event.h	2800	event.h
2705	event.c	2801	event.c
2706		2802
2707	=head3 AUTOCONF SUPPORT	2803	=head3 AUTOCONF SUPPORT
2708		2804
2709	Instead of using C<EV_STANDALONE=1> and providing your config in	2805	Instead of using C<EV_STANDALONE=1> and providing your configuration in
2710	whatever way you want, you can also C<m4_include([libev.m4])> in your	2806	whatever way you want, you can also C<m4_include([libev.m4])> in your
2711	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then	2807	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then
2712	include F<config.h> and configure itself accordingly.	2808	include F<config.h> and configure itself accordingly.
2713		2809
2714	For this of course you need the m4 file:	2810	For this of course you need the m4 file:
2715		2811
2716	libev.m4	2812	libev.m4
2717		2813
2718	=head2 PREPROCESSOR SYMBOLS/MACROS	2814	=head2 PREPROCESSOR SYMBOLS/MACROS
2719		2815
2720	Libev can be configured via a variety of preprocessor symbols you have to define	2816	Libev can be configured via a variety of preprocessor symbols you have to
2721	before including any of its files. The default is not to build for multiplicity	2817	define before including any of its files. The default in the absence of
2722	and only include the select backend.	2818	autoconf is noted for every option.
2723		2819
2724	=over 4	2820	=over 4
2725		2821
2726	=item EV_STANDALONE	2822	=item EV_STANDALONE
2727		2823
…		…
2732	F<event.h> that are not directly supported by the libev core alone.	2828	F<event.h> that are not directly supported by the libev core alone.
2733		2829
2734	=item EV_USE_MONOTONIC	2830	=item EV_USE_MONOTONIC
2735		2831
2736	If defined to be C<1>, libev will try to detect the availability of the	2832	If defined to be C<1>, libev will try to detect the availability of the
2737	monotonic clock option at both compiletime and runtime. Otherwise no use	2833	monotonic clock option at both compile time and runtime. Otherwise no use
2738	of the monotonic clock option will be attempted. If you enable this, you	2834	of the monotonic clock option will be attempted. If you enable this, you
2739	usually have to link against librt or something similar. Enabling it when	2835	usually have to link against librt or something similar. Enabling it when
2740	the functionality isn't available is safe, though, although you have	2836	the functionality isn't available is safe, though, although you have
2741	to make sure you link against any libraries where the C<clock_gettime>	2837	to make sure you link against any libraries where the C<clock_gettime>
2742	function is hiding in (often F<-lrt>).	2838	function is hiding in (often F<-lrt>).
2743		2839
2744	=item EV_USE_REALTIME	2840	=item EV_USE_REALTIME
2745		2841
2746	If defined to be C<1>, libev will try to detect the availability of the	2842	If defined to be C<1>, libev will try to detect the availability of the
2747	realtime clock option at compiletime (and assume its availability at	2843	real-time clock option at compile time (and assume its availability at
2748	runtime if successful). Otherwise no use of the realtime clock option will	2844	runtime if successful). Otherwise no use of the real-time clock option will
2749	be attempted. This effectively replaces C<gettimeofday> by C<clock_get	2845	be attempted. This effectively replaces C<gettimeofday> by C<clock_get
2750	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the	2846	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the
2751	note about libraries in the description of C<EV_USE_MONOTONIC>, though.	2847	note about libraries in the description of C<EV_USE_MONOTONIC>, though.
2752		2848
2753	=item EV_USE_NANOSLEEP	2849	=item EV_USE_NANOSLEEP
2754		2850
2755	If defined to be C<1>, libev will assume that C<nanosleep ()> is available	2851	If defined to be C<1>, libev will assume that C<nanosleep ()> is available
2756	and will use it for delays. Otherwise it will use C<select ()>.	2852	and will use it for delays. Otherwise it will use C<select ()>.
2757		2853
		2854	=item EV_USE_EVENTFD
		2855
		2856	If defined to be C<1>, then libev will assume that C<eventfd ()> is
		2857	available and will probe for kernel support at runtime. This will improve
		2858	C<ev_signal> and C<ev_async> performance and reduce resource consumption.
		2859	If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc
		2860	2.7 or newer, otherwise disabled.
		2861
2758	=item EV_USE_SELECT	2862	=item EV_USE_SELECT
2759		2863
2760	If undefined or defined to be C<1>, libev will compile in support for the	2864	If undefined or defined to be C<1>, libev will compile in support for the
2761	C<select>(2) backend. No attempt at autodetection will be done: if no	2865	C<select>(2) backend. No attempt at auto-detection will be done: if no
2762	other method takes over, select will be it. Otherwise the select backend	2866	other method takes over, select will be it. Otherwise the select backend
2763	will not be compiled in.	2867	will not be compiled in.
2764		2868
2765	=item EV_SELECT_USE_FD_SET	2869	=item EV_SELECT_USE_FD_SET
2766		2870
2767	If defined to C<1>, then the select backend will use the system C<fd_set>	2871	If defined to C<1>, then the select backend will use the system C<fd_set>
2768	structure. This is useful if libev doesn't compile due to a missing	2872	structure. This is useful if libev doesn't compile due to a missing
2769	C<NFDBITS> or C<fd_mask> definition or it misguesses the bitset layout on	2873	C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout on
2770	exotic systems. This usually limits the range of file descriptors to some	2874	exotic systems. This usually limits the range of file descriptors to some
2771	low limit such as 1024 or might have other limitations (winsocket only	2875	low limit such as 1024 or might have other limitations (winsocket only
2772	allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might	2876	allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might
2773	influence the size of the C<fd_set> used.	2877	influence the size of the C<fd_set> used.
2774		2878
…		…
2798		2902
2799	=item EV_USE_EPOLL	2903	=item EV_USE_EPOLL
2800		2904
2801	If defined to be C<1>, libev will compile in support for the Linux	2905	If defined to be C<1>, libev will compile in support for the Linux
2802	C<epoll>(7) backend. Its availability will be detected at runtime,	2906	C<epoll>(7) backend. Its availability will be detected at runtime,
2803	otherwise another method will be used as fallback. This is the	2907	otherwise another method will be used as fallback. This is the preferred
2804	preferred backend for GNU/Linux systems.	2908	backend for GNU/Linux systems. If undefined, it will be enabled if the
		2909	headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled.
2805		2910
2806	=item EV_USE_KQUEUE	2911	=item EV_USE_KQUEUE
2807		2912
2808	If defined to be C<1>, libev will compile in support for the BSD style	2913	If defined to be C<1>, libev will compile in support for the BSD style
2809	C<kqueue>(2) backend. Its actual availability will be detected at runtime,	2914	C<kqueue>(2) backend. Its actual availability will be detected at runtime,
…		…
2822	otherwise another method will be used as fallback. This is the preferred	2927	otherwise another method will be used as fallback. This is the preferred
2823	backend for Solaris 10 systems.	2928	backend for Solaris 10 systems.
2824		2929
2825	=item EV_USE_DEVPOLL	2930	=item EV_USE_DEVPOLL
2826		2931
2827	reserved for future expansion, works like the USE symbols above.	2932	Reserved for future expansion, works like the USE symbols above.
2828		2933
2829	=item EV_USE_INOTIFY	2934	=item EV_USE_INOTIFY
2830		2935
2831	If defined to be C<1>, libev will compile in support for the Linux inotify	2936	If defined to be C<1>, libev will compile in support for the Linux inotify
2832	interface to speed up C<ev_stat> watchers. Its actual availability will	2937	interface to speed up C<ev_stat> watchers. Its actual availability will
2833	be detected at runtime.	2938	be detected at runtime. If undefined, it will be enabled if the headers
		2939	indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled.
2834		2940
2835	=item EV_ATOMIC_T	2941	=item EV_ATOMIC_T
2836		2942
2837	Libev requires an integer type (suitable for storing C<0> or C<1>) whose	2943	Libev requires an integer type (suitable for storing C<0> or C<1>) whose
2838	access is atomic with respect to other threads or signal contexts. No such	2944	access is atomic with respect to other threads or signal contexts. No such
2839	type is easily found in the C language, so you can provide your own type	2945	type is easily found in the C language, so you can provide your own type
2840	that you know is safe for your purposes. It is used both for signal handler "locking"	2946	that you know is safe for your purposes. It is used both for signal handler "locking"
2841	as well as for signal and thread safety in C<ev_async> watchers.	2947	as well as for signal and thread safety in C<ev_async> watchers.
2842		2948
2843	In the absense of this define, libev will use C<sig_atomic_t volatile>	2949	In the absence of this define, libev will use C<sig_atomic_t volatile>
2844	(from F<signal.h>), which is usually good enough on most platforms.	2950	(from F<signal.h>), which is usually good enough on most platforms.
2845		2951
2846	=item EV_H	2952	=item EV_H
2847		2953
2848	The name of the F<ev.h> header file used to include it. The default if	2954	The name of the F<ev.h> header file used to include it. The default if
…		…
2887	When doing priority-based operations, libev usually has to linearly search	2993	When doing priority-based operations, libev usually has to linearly search
2888	all the priorities, so having many of them (hundreds) uses a lot of space	2994	all the priorities, so having many of them (hundreds) uses a lot of space
2889	and time, so using the defaults of five priorities (-2 .. +2) is usually	2995	and time, so using the defaults of five priorities (-2 .. +2) is usually
2890	fine.	2996	fine.
2891		2997
2892	If your embedding app does not need any priorities, defining these both to	2998	If your embedding application does not need any priorities, defining these both to
2893	C<0> will save some memory and cpu.	2999	C<0> will save some memory and CPU.
2894		3000
2895	=item EV_PERIODIC_ENABLE	3001	=item EV_PERIODIC_ENABLE
2896		3002
2897	If undefined or defined to be C<1>, then periodic timers are supported. If	3003	If undefined or defined to be C<1>, then periodic timers are supported. If
2898	defined to be C<0>, then they are not. Disabling them saves a few kB of	3004	defined to be C<0>, then they are not. Disabling them saves a few kB of
…		…
2925	defined to be C<0>, then they are not.	3031	defined to be C<0>, then they are not.
2926		3032
2927	=item EV_MINIMAL	3033	=item EV_MINIMAL
2928		3034
2929	If you need to shave off some kilobytes of code at the expense of some	3035	If you need to shave off some kilobytes of code at the expense of some
2930	speed, define this symbol to C<1>. Currently only used for gcc to override	3036	speed, define this symbol to C<1>. Currently this is used to override some
2931	some inlining decisions, saves roughly 30% codesize of amd64.	3037	inlining decisions, saves roughly 30% code size on amd64. It also selects a
		3038	much smaller 2-heap for timer management over the default 4-heap.
2932		3039
2933	=item EV_PID_HASHSIZE	3040	=item EV_PID_HASHSIZE
2934		3041
2935	C<ev_child> watchers use a small hash table to distribute workload by	3042	C<ev_child> watchers use a small hash table to distribute workload by
2936	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more	3043	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
…		…
2943	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),	3050	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
2944	usually more than enough. If you need to manage thousands of C<ev_stat>	3051	usually more than enough. If you need to manage thousands of C<ev_stat>
2945	watchers you might want to increase this value (I<must> be a power of	3052	watchers you might want to increase this value (I<must> be a power of
2946	two).	3053	two).
2947		3054
		3055	=item EV_USE_4HEAP
		3056
		3057	Heaps are not very cache-efficient. To improve the cache-efficiency of the
		3058	timer and periodics heap, libev uses a 4-heap when this symbol is defined
		3059	to C<1>. The 4-heap uses more complicated (longer) code but has
		3060	noticeably faster performance with many (thousands) of watchers.
		3061
		3062	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>
		3063	(disabled).
		3064
		3065	=item EV_HEAP_CACHE_AT
		3066
		3067	Heaps are not very cache-efficient. To improve the cache-efficiency of the
		3068	timer and periodics heap, libev can cache the timestamp (I<at>) within
		3069	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),
		3070	which uses 8-12 bytes more per watcher and a few hundred bytes more code,
		3071	but avoids random read accesses on heap changes. This improves performance
		3072	noticeably with with many (hundreds) of watchers.
		3073
		3074	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>
		3075	(disabled).
		3076
		3077	=item EV_VERIFY
		3078
		3079	Controls how much internal verification (see C<ev_loop_verify ()>) will
		3080	be done: If set to C<0>, no internal verification code will be compiled
		3081	in. If set to C<1>, then verification code will be compiled in, but not
		3082	called. If set to C<2>, then the internal verification code will be
		3083	called once per loop, which can slow down libev. If set to C<3>, then the
		3084	verification code will be called very frequently, which will slow down
		3085	libev considerably.
		3086
		3087	The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be
		3088	C<0.>
		3089
2948	=item EV_COMMON	3090	=item EV_COMMON
2949		3091
2950	By default, all watchers have a C<void *data> member. By redefining	3092	By default, all watchers have a C<void *data> member. By redefining
2951	this macro to a something else you can include more and other types of	3093	this macro to a something else you can include more and other types of
2952	members. You have to define it each time you include one of the files,	3094	members. You have to define it each time you include one of the files,
2953	though, and it must be identical each time.	3095	though, and it must be identical each time.
2954		3096
2955	For example, the perl EV module uses something like this:	3097	For example, the perl EV module uses something like this:
2956		3098
2957	#define EV_COMMON \	3099	#define EV_COMMON \
2958	SV *self; /* contains this struct */ \	3100	SV *self; /* contains this struct */ \
2959	SV *cb_sv, *fh /* note no trailing ";" */	3101	SV *cb_sv, *fh /* note no trailing ";" */
2960		3102
2961	=item EV_CB_DECLARE (type)	3103	=item EV_CB_DECLARE (type)
2962		3104
2963	=item EV_CB_INVOKE (watcher, revents)	3105	=item EV_CB_INVOKE (watcher, revents)
2964		3106
…		…
2971	avoid the C<struct ev_loop *> as first argument in all cases, or to use	3113	avoid the C<struct ev_loop *> as first argument in all cases, or to use
2972	method calls instead of plain function calls in C++.	3114	method calls instead of plain function calls in C++.
2973		3115
2974	=head2 EXPORTED API SYMBOLS	3116	=head2 EXPORTED API SYMBOLS
2975		3117
2976	If you need to re-export the API (e.g. via a dll) and you need a list of	3118	If you need to re-export the API (e.g. via a DLL) and you need a list of
2977	exported symbols, you can use the provided F<Symbol.*> files which list	3119	exported symbols, you can use the provided F<Symbol.*> files which list
2978	all public symbols, one per line:	3120	all public symbols, one per line:
2979		3121
2980	Symbols.ev for libev proper	3122	Symbols.ev for libev proper
2981	Symbols.event for the libevent emulation	3123	Symbols.event for the libevent emulation
2982		3124
2983	This can also be used to rename all public symbols to avoid clashes with	3125	This can also be used to rename all public symbols to avoid clashes with
2984	multiple versions of libev linked together (which is obviously bad in	3126	multiple versions of libev linked together (which is obviously bad in
2985	itself, but sometimes it is inconvinient to avoid this).	3127	itself, but sometimes it is inconvenient to avoid this).
2986		3128
2987	A sed command like this will create wrapper C<#define>'s that you need to	3129	A sed command like this will create wrapper C<#define>'s that you need to
2988	include before including F<ev.h>:	3130	include before including F<ev.h>:
2989		3131
2990	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h	3132	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h
…		…
3007	file.	3149	file.
3008		3150
3009	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	3151	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
3010	that everybody includes and which overrides some configure choices:	3152	that everybody includes and which overrides some configure choices:
3011		3153
3012	#define EV_MINIMAL 1	3154	#define EV_MINIMAL 1
3013	#define EV_USE_POLL 0	3155	#define EV_USE_POLL 0
3014	#define EV_MULTIPLICITY 0	3156	#define EV_MULTIPLICITY 0
3015	#define EV_PERIODIC_ENABLE 0	3157	#define EV_PERIODIC_ENABLE 0
3016	#define EV_STAT_ENABLE 0	3158	#define EV_STAT_ENABLE 0
3017	#define EV_FORK_ENABLE 0	3159	#define EV_FORK_ENABLE 0
3018	#define EV_CONFIG_H <config.h>	3160	#define EV_CONFIG_H <config.h>
3019	#define EV_MINPRI 0	3161	#define EV_MINPRI 0
3020	#define EV_MAXPRI 0	3162	#define EV_MAXPRI 0
3021		3163
3022	#include "ev++.h"	3164	#include "ev++.h"
3023		3165
3024	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	3166	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
3025		3167
3026	#include "ev_cpp.h"	3168	#include "ev_cpp.h"
3027	#include "ev.c"	3169	#include "ev.c"
		3170
		3171
		3172	=head1 THREADS AND COROUTINES
		3173
		3174	=head2 THREADS
		3175
		3176	Libev itself is completely thread-safe, but it uses no locking. This
		3177	means that you can use as many loops as you want in parallel, as long as
		3178	only one thread ever calls into one libev function with the same loop
		3179	parameter.
		3180
		3181	Or put differently: calls with different loop parameters can be done in
		3182	parallel from multiple threads, calls with the same loop parameter must be
		3183	done serially (but can be done from different threads, as long as only one
		3184	thread ever is inside a call at any point in time, e.g. by using a mutex
		3185	per loop).
		3186
		3187	If you want to know which design is best for your problem, then I cannot
		3188	help you but by giving some generic advice:
		3189
		3190	=over 4
		3191
		3192	=item * most applications have a main thread: use the default libev loop
		3193	in that thread, or create a separate thread running only the default loop.
		3194
		3195	This helps integrating other libraries or software modules that use libev
		3196	themselves and don't care/know about threading.
		3197
		3198	=item * one loop per thread is usually a good model.
		3199
		3200	Doing this is almost never wrong, sometimes a better-performance model
		3201	exists, but it is always a good start.
		3202
		3203	=item * other models exist, such as the leader/follower pattern, where one
		3204	loop is handed through multiple threads in a kind of round-robin fashion.
		3205
		3206	Choosing a model is hard - look around, learn, know that usually you can do
		3207	better than you currently do :-)
		3208
		3209	=item * often you need to talk to some other thread which blocks in the
		3210	event loop - C<ev_async> watchers can be used to wake them up from other
		3211	threads safely (or from signal contexts...).
		3212
		3213	=back
		3214
		3215	=head2 COROUTINES
		3216
		3217	Libev is much more accommodating to coroutines ("cooperative threads"):
		3218	libev fully supports nesting calls to it's functions from different
		3219	coroutines (e.g. you can call C<ev_loop> on the same loop from two
		3220	different coroutines and switch freely between both coroutines running the
		3221	loop, as long as you don't confuse yourself). The only exception is that
		3222	you must not do this from C<ev_periodic> reschedule callbacks.
		3223
		3224	Care has been invested into making sure that libev does not keep local
		3225	state inside C<ev_loop>, and other calls do not usually allow coroutine
		3226	switches.
3028		3227
3029		3228
3030	=head1 COMPLEXITIES	3229	=head1 COMPLEXITIES
3031		3230
3032	In this section the complexities of (many of) the algorithms used inside	3231	In this section the complexities of (many of) the algorithms used inside
…		…
3064	correct watcher to remove. The lists are usually short (you don't usually	3263	correct watcher to remove. The lists are usually short (you don't usually
3065	have many watchers waiting for the same fd or signal).	3264	have many watchers waiting for the same fd or signal).
3066		3265
3067	=item Finding the next timer in each loop iteration: O(1)	3266	=item Finding the next timer in each loop iteration: O(1)
3068		3267
3069	By virtue of using a binary heap, the next timer is always found at the	3268	By virtue of using a binary or 4-heap, the next timer is always found at a
3070	beginning of the storage array.	3269	fixed position in the storage array.
3071		3270
3072	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	3271	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
3073		3272
3074	A change means an I/O watcher gets started or stopped, which requires	3273	A change means an I/O watcher gets started or stopped, which requires
3075	libev to recalculate its status (and possibly tell the kernel, depending	3274	libev to recalculate its status (and possibly tell the kernel, depending
3076	on backend and wether C<ev_io_set> was used).	3275	on backend and whether C<ev_io_set> was used).
3077		3276
3078	=item Activating one watcher (putting it into the pending state): O(1)	3277	=item Activating one watcher (putting it into the pending state): O(1)
3079		3278
3080	=item Priority handling: O(number_of_priorities)	3279	=item Priority handling: O(number_of_priorities)
3081		3280
…		…
3088		3287
3089	=item Processing ev_async_send: O(number_of_async_watchers)	3288	=item Processing ev_async_send: O(number_of_async_watchers)
3090		3289
3091	=item Processing signals: O(max_signal_number)	3290	=item Processing signals: O(max_signal_number)
3092		3291
3093	Sending involves a syscall I<iff> there were no other C<ev_async_send>	3292	Sending involves a system call I<iff> there were no other C<ev_async_send>
3094	calls in the current loop iteration. Checking for async and signal events	3293	calls in the current loop iteration. Checking for async and signal events
3095	involves iterating over all running async watchers or all signal numbers.	3294	involves iterating over all running async watchers or all signal numbers.
3096		3295
3097	=back	3296	=back
3098		3297
3099		3298
3100	=head1 Win32 platform limitations and workarounds	3299	=head1 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
3101		3300
3102	Win32 doesn't support any of the standards (e.g. POSIX) that libev	3301	Win32 doesn't support any of the standards (e.g. POSIX) that libev
3103	requires, and its I/O model is fundamentally incompatible with the POSIX	3302	requires, and its I/O model is fundamentally incompatible with the POSIX
3104	model. Libev still offers limited functionality on this platform in	3303	model. Libev still offers limited functionality on this platform in
3105	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	3304	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
3106	descriptors. This only applies when using Win32 natively, not when using	3305	descriptors. This only applies when using Win32 natively, not when using
3107	e.g. cygwin.	3306	e.g. cygwin.
3108		3307
		3308	Lifting these limitations would basically require the full
		3309	re-implementation of the I/O system. If you are into these kinds of
		3310	things, then note that glib does exactly that for you in a very portable
		3311	way (note also that glib is the slowest event library known to man).
		3312
3109	There is no supported compilation method available on windows except	3313	There is no supported compilation method available on windows except
3110	embedding it into other applications.	3314	embedding it into other applications.
3111		3315
		3316	Not a libev limitation but worth mentioning: windows apparently doesn't
		3317	accept large writes: instead of resulting in a partial write, windows will
		3318	either accept everything or return C<ENOBUFS> if the buffer is too large,
		3319	so make sure you only write small amounts into your sockets (less than a
		3320	megabyte seems safe, but thsi apparently depends on the amount of memory
		3321	available).
		3322
3112	Due to the many, low, and arbitrary limits on the win32 platform and the	3323	Due to the many, low, and arbitrary limits on the win32 platform and
3113	abysmal performance of winsockets, using a large number of sockets is not	3324	the abysmal performance of winsockets, using a large number of sockets
3114	recommended (and not reasonable). If your program needs to use more than	3325	is not recommended (and not reasonable). If your program needs to use
3115	a hundred or so sockets, then likely it needs to use a totally different	3326	more than a hundred or so sockets, then likely it needs to use a totally
3116	implementation for windows, as libev offers the POSIX model, which cannot	3327	different implementation for windows, as libev offers the POSIX readiness
3117	be implemented efficiently on windows (microsoft monopoly games).	3328	notification model, which cannot be implemented efficiently on windows
		3329	(Microsoft monopoly games).
		3330
		3331	A typical way to use libev under windows is to embed it (see the embedding
		3332	section for details) and use the following F<evwrap.h> header file instead
		3333	of F<ev.h>:
		3334
		3335	#define EV_STANDALONE /* keeps ev from requiring config.h */
		3336	#define EV_SELECT_IS_WINSOCKET 1 /* configure libev for windows select */
		3337
		3338	#include "ev.h"
		3339
		3340	And compile the following F<evwrap.c> file into your project (make sure
		3341	you do I<not> compile the F<ev.c> or any other embedded soruce files!):
		3342
		3343	#include "evwrap.h"
		3344	#include "ev.c"
3118		3345
3119	=over 4	3346	=over 4
3120		3347
3121	=item The winsocket select function	3348	=item The winsocket select function
3122		3349
3123	The winsocket C<select> function doesn't follow POSIX in that it requires	3350	The winsocket C<select> function doesn't follow POSIX in that it
3124	socket I<handles> and not socket I<file descriptors>. This makes select	3351	requires socket I<handles> and not socket I<file descriptors> (it is
3125	very inefficient, and also requires a mapping from file descriptors	3352	also extremely buggy). This makes select very inefficient, and also
3126	to socket handles. See the discussion of the C<EV_SELECT_USE_FD_SET>,	3353	requires a mapping from file descriptors to socket handles (the Microsoft
3127	C<EV_SELECT_IS_WINSOCKET> and C<EV_FD_TO_WIN32_HANDLE> preprocessor	3354	C runtime provides the function C<_open_osfhandle> for this). See the
3128	symbols for more info.	3355	discussion of the C<EV_SELECT_USE_FD_SET>, C<EV_SELECT_IS_WINSOCKET> and
		3356	C<EV_FD_TO_WIN32_HANDLE> preprocessor symbols for more info.
3129		3357
3130	The configuration for a "naked" win32 using the microsoft runtime	3358	The configuration for a "naked" win32 using the Microsoft runtime
3131	libraries and raw winsocket select is:	3359	libraries and raw winsocket select is:
3132		3360
3133	#define EV_USE_SELECT 1	3361	#define EV_USE_SELECT 1
3134	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */	3362	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
3135		3363
3136	Note that winsockets handling of fd sets is O(n), so you can easily get a	3364	Note that winsockets handling of fd sets is O(n), so you can easily get a
3137	complexity in the O(n²) range when using win32.	3365	complexity in the O(n²) range when using win32.
3138		3366
3139	=item Limited number of file descriptors	3367	=item Limited number of file descriptors
3140		3368
3141	Windows has numerous arbitrary (and low) limits on things. Early versions	3369	Windows has numerous arbitrary (and low) limits on things.
3142	of winsocket's select only supported waiting for a max. of C<64> handles	3370
		3371	Early versions of winsocket's select only supported waiting for a maximum
3143	(probably owning to the fact that all windows kernels can only wait for	3372	of C<64> handles (probably owning to the fact that all windows kernels
3144	C<64> things at the same time internally; microsoft recommends spawning a	3373	can only wait for C<64> things at the same time internally; Microsoft
3145	chain of threads and wait for 63 handles and the previous thread in each).	3374	recommends spawning a chain of threads and wait for 63 handles and the
		3375	previous thread in each. Great).
3146		3376
3147	Newer versions support more handles, but you need to define C<FD_SETSIZE>	3377	Newer versions support more handles, but you need to define C<FD_SETSIZE>
3148	to some high number (e.g. C<2048>) before compiling the winsocket select	3378	to some high number (e.g. C<2048>) before compiling the winsocket select
3149	call (which might be in libev or elsewhere, for example, perl does its own	3379	call (which might be in libev or elsewhere, for example, perl does its own
3150	select emulation on windows).	3380	select emulation on windows).
3151		3381
3152	Another limit is the number of file descriptors in the microsoft runtime	3382	Another limit is the number of file descriptors in the Microsoft runtime
3153	libraries, which by default is C<64> (there must be a hidden I<64> fetish	3383	libraries, which by default is C<64> (there must be a hidden I<64> fetish
3154	or something like this inside microsoft). You can increase this by calling	3384	or something like this inside Microsoft). You can increase this by calling
3155	C<_setmaxstdio>, which can increase this limit to C<2048> (another	3385	C<_setmaxstdio>, which can increase this limit to C<2048> (another
3156	arbitrary limit), but is broken in many versions of the microsoft runtime	3386	arbitrary limit), but is broken in many versions of the Microsoft runtime
3157	libraries.	3387	libraries.
3158		3388
3159	This might get you to about C<512> or C<2048> sockets (depending on	3389	This might get you to about C<512> or C<2048> sockets (depending on
3160	windows version and/or the phase of the moon). To get more, you need to	3390	windows version and/or the phase of the moon). To get more, you need to
3161	wrap all I/O functions and provide your own fd management, but the cost of	3391	wrap all I/O functions and provide your own fd management, but the cost of
3162	calling select (O(n²)) will likely make this unworkable.	3392	calling select (O(n²)) will likely make this unworkable.
3163		3393
3164	=back	3394	=back
3165		3395
3166		3396
		3397	=head1 PORTABILITY REQUIREMENTS
		3398
		3399	In addition to a working ISO-C implementation, libev relies on a few
		3400	additional extensions:
		3401
		3402	=over 4
		3403
		3404	=item C<void (*)(ev_watcher_type *, int revents)> must have compatible
		3405	calling conventions regardless of C<ev_watcher_type *>.
		3406
		3407	Libev assumes not only that all watcher pointers have the same internal
		3408	structure (guaranteed by POSIX but not by ISO C for example), but it also
		3409	assumes that the same (machine) code can be used to call any watcher
		3410	callback: The watcher callbacks have different type signatures, but libev
		3411	calls them using an C<ev_watcher *> internally.
		3412
		3413	=item C<sig_atomic_t volatile> must be thread-atomic as well
		3414
		3415	The type C<sig_atomic_t volatile> (or whatever is defined as
		3416	C<EV_ATOMIC_T>) must be atomic w.r.t. accesses from different
		3417	threads. This is not part of the specification for C<sig_atomic_t>, but is
		3418	believed to be sufficiently portable.
		3419
		3420	=item C<sigprocmask> must work in a threaded environment
		3421
		3422	Libev uses C<sigprocmask> to temporarily block signals. This is not
		3423	allowed in a threaded program (C<pthread_sigmask> has to be used). Typical
		3424	pthread implementations will either allow C<sigprocmask> in the "main
		3425	thread" or will block signals process-wide, both behaviours would
		3426	be compatible with libev. Interaction between C<sigprocmask> and
		3427	C<pthread_sigmask> could complicate things, however.
		3428
		3429	The most portable way to handle signals is to block signals in all threads
		3430	except the initial one, and run the default loop in the initial thread as
		3431	well.
		3432
		3433	=item C<long> must be large enough for common memory allocation sizes
		3434
		3435	To improve portability and simplify using libev, libev uses C<long>
		3436	internally instead of C<size_t> when allocating its data structures. On
		3437	non-POSIX systems (Microsoft...) this might be unexpectedly low, but
		3438	is still at least 31 bits everywhere, which is enough for hundreds of
		3439	millions of watchers.
		3440
		3441	=item C<double> must hold a time value in seconds with enough accuracy
		3442
		3443	The type C<double> is used to represent timestamps. It is required to
		3444	have at least 51 bits of mantissa (and 9 bits of exponent), which is good
		3445	enough for at least into the year 4000. This requirement is fulfilled by
		3446	implementations implementing IEEE 754 (basically all existing ones).
		3447
		3448	=back
		3449
		3450	If you know of other additional requirements drop me a note.
		3451
		3452
		3453	=head1 COMPILER WARNINGS
		3454
		3455	Depending on your compiler and compiler settings, you might get no or a
		3456	lot of warnings when compiling libev code. Some people are apparently
		3457	scared by this.
		3458
		3459	However, these are unavoidable for many reasons. For one, each compiler
		3460	has different warnings, and each user has different tastes regarding
		3461	warning options. "Warn-free" code therefore cannot be a goal except when
		3462	targeting a specific compiler and compiler-version.
		3463
		3464	Another reason is that some compiler warnings require elaborate
		3465	workarounds, or other changes to the code that make it less clear and less
		3466	maintainable.
		3467
		3468	And of course, some compiler warnings are just plain stupid, or simply
		3469	wrong (because they don't actually warn about the condition their message
		3470	seems to warn about).
		3471
		3472	While libev is written to generate as few warnings as possible,
		3473	"warn-free" code is not a goal, and it is recommended not to build libev
		3474	with any compiler warnings enabled unless you are prepared to cope with
		3475	them (e.g. by ignoring them). Remember that warnings are just that:
		3476	warnings, not errors, or proof of bugs.
		3477
		3478
		3479	=head1 VALGRIND
		3480
		3481	Valgrind has a special section here because it is a popular tool that is
		3482	highly useful, but valgrind reports are very hard to interpret.
		3483
		3484	If you think you found a bug (memory leak, uninitialised data access etc.)
		3485	in libev, then check twice: If valgrind reports something like:
		3486
		3487	==2274== definitely lost: 0 bytes in 0 blocks.
		3488	==2274== possibly lost: 0 bytes in 0 blocks.
		3489	==2274== still reachable: 256 bytes in 1 blocks.
		3490
		3491	Then there is no memory leak. Similarly, under some circumstances,
		3492	valgrind might report kernel bugs as if it were a bug in libev, or it
		3493	might be confused (it is a very good tool, but only a tool).
		3494
		3495	If you are unsure about something, feel free to contact the mailing list
		3496	with the full valgrind report and an explanation on why you think this is
		3497	a bug in libev. However, don't be annoyed when you get a brisk "this is
		3498	no bug" answer and take the chance of learning how to interpret valgrind
		3499	properly.
		3500
		3501	If you need, for some reason, empty reports from valgrind for your project
		3502	I suggest using suppression lists.
		3503
		3504
3167	=head1 AUTHOR	3505	=head1 AUTHOR
3168		3506
3169	Marc Lehmann <libev@schmorp.de>.	3507	Marc Lehmann <libev@schmorp.de>.
3170		3508

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