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Revision 1.138 by root, Mon Mar 31 01:14:12 2008 UTC vs.
Revision 1.176 by root, Mon Sep 8 17:24:39 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
…		…
548	received events and started processing them. This timestamp does not	573	received events and started processing them. This timestamp does not
549	change as long as callbacks are being processed, and this is also the base	574	change as long as callbacks are being processed, and this is also the base
550	time used for relative timers. You can treat it as the timestamp of the	575	time used for relative timers. You can treat it as the timestamp of the
551	event occurring (or more correctly, libev finding out about it).	576	event occurring (or more correctly, libev finding out about it).
552		577
		578	=item ev_now_update (loop)
		579
		580	Establishes the current time by querying the kernel, updating the time
		581	returned by C<ev_now ()> in the progress. This is a costly operation and
		582	is usually done automatically within C<ev_loop ()>.
		583
		584	This function is rarely useful, but when some event callback runs for a
		585	very long time without entering the event loop, updating libev's idea of
		586	the current time is a good idea.
		587
		588	See also "The special problem of time updates" in the C<ev_timer> section.
		589
553	=item ev_loop (loop, int flags)	590	=item ev_loop (loop, int flags)
554		591
555	Finally, this is it, the event handler. This function usually is called	592	Finally, this is it, the event handler. This function usually is called
556	after you initialised all your watchers and you want to start handling	593	after you initialised all your watchers and you want to start handling
557	events.	594	events.
…		…
568	A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle	605	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	606	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.	607	case there are no events and will return after one iteration of the loop.
571		608
572	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if	609	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	610	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	611	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	612	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	613	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	614	libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is
578	usually a better approach for this kind of thing.	615	usually a better approach for this kind of thing.
579		616
580	Here are the gory details of what C<ev_loop> does:	617	Here are the gory details of what C<ev_loop> does:
581		618
582	- Before the first iteration, call any pending watchers.	619	- Before the first iteration, call any pending watchers.
583	* If EVFLAG_FORKCHECK was used, check for a fork.	620	* If EVFLAG_FORKCHECK was used, check for a fork.
584	- If a fork was detected, queue and call all fork watchers.	621	- If a fork was detected (by any means), queue and call all fork watchers.
585	- Queue and call all prepare watchers.	622	- Queue and call all prepare watchers.
586	- If we have been forked, recreate the kernel state.	623	- If we have been forked, detach and recreate the kernel state
		624	as to not disturb the other process.
587	- Update the kernel state with all outstanding changes.	625	- Update the kernel state with all outstanding changes.
588	- Update the "event loop time".	626	- Update the "event loop time" (ev_now ()).
589	- Calculate for how long to sleep or block, if at all	627	- Calculate for how long to sleep or block, if at all
590	(active idle watchers, EVLOOP_NONBLOCK or not having	628	(active idle watchers, EVLOOP_NONBLOCK or not having
591	any active watchers at all will result in not sleeping).	629	any active watchers at all will result in not sleeping).
592	- Sleep if the I/O and timer collect interval say so.	630	- Sleep if the I/O and timer collect interval say so.
593	- Block the process, waiting for any events.	631	- Block the process, waiting for any events.
594	- Queue all outstanding I/O (fd) events.	632	- Queue all outstanding I/O (fd) events.
595	- Update the "event loop time" and do time jump handling.	633	- Update the "event loop time" (ev_now ()), and do time jump adjustments.
596	- Queue all outstanding timers.	634	- Queue all outstanding timers.
597	- Queue all outstanding periodics.	635	- Queue all outstanding periodics.
598	- If no events are pending now, queue all idle watchers.	636	- Unless any events are pending now, queue all idle watchers.
599	- Queue all check watchers.	637	- Queue all check watchers.
600	- Call all queued watchers in reverse order (i.e. check watchers first).	638	- Call all queued watchers in reverse order (i.e. check watchers first).
601	Signals and child watchers are implemented as I/O watchers, and will	639	Signals and child watchers are implemented as I/O watchers, and will
602	be handled here by queueing them when their watcher gets executed.	640	be handled here by queueing them when their watcher gets executed.
603	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	641	- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
…		…
608	anymore.	646	anymore.
609		647
610	... queue jobs here, make sure they register event watchers as long	648	... queue jobs here, make sure they register event watchers as long
611	... as they still have work to do (even an idle watcher will do..)	649	... as they still have work to do (even an idle watcher will do..)
612	ev_loop (my_loop, 0);	650	ev_loop (my_loop, 0);
613	... jobs done. yeah!	651	... jobs done or somebody called unloop. yeah!
614		652
615	=item ev_unloop (loop, how)	653	=item ev_unloop (loop, how)
616		654
617	Can be used to make a call to C<ev_loop> return early (but only after it	655	Can be used to make a call to C<ev_loop> return early (but only after it
618	has processed all outstanding events). The C<how> argument must be either	656	has processed all outstanding events). The C<how> argument must be either
…		…
639	respectively).	677	respectively).
640		678
641	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	679	Example: Create a signal watcher, but keep it from keeping C<ev_loop>
642	running when nothing else is active.	680	running when nothing else is active.
643		681
644	struct ev_signal exitsig;	682	struct ev_signal exitsig;
645	ev_signal_init (&exitsig, sig_cb, SIGINT);	683	ev_signal_init (&exitsig, sig_cb, SIGINT);
646	ev_signal_start (loop, &exitsig);	684	ev_signal_start (loop, &exitsig);
647	evf_unref (loop);	685	evf_unref (loop);
648		686
649	Example: For some weird reason, unregister the above signal handler again.	687	Example: For some weird reason, unregister the above signal handler again.
650		688
651	ev_ref (loop);	689	ev_ref (loop);
652	ev_signal_stop (loop, &exitsig);	690	ev_signal_stop (loop, &exitsig);
653		691
654	=item ev_set_io_collect_interval (loop, ev_tstamp interval)	692	=item ev_set_io_collect_interval (loop, ev_tstamp interval)
655		693
656	=item ev_set_timeout_collect_interval (loop, ev_tstamp interval)	694	=item ev_set_timeout_collect_interval (loop, ev_tstamp interval)
657		695
658	These advanced functions influence the time that libev will spend waiting	696	These advanced functions influence the time that libev will spend waiting
659	for events. Both are by default C<0>, meaning that libev will try to	697	for events. Both time intervals are by default C<0>, meaning that libev
660	invoke timer/periodic callbacks and I/O callbacks with minimum latency.	698	will try to invoke timer/periodic callbacks and I/O callbacks with minimum
		699	latency.
661		700
662	Setting these to a higher value (the C<interval> I<must> be >= C<0>)	701	Setting these to a higher value (the C<interval> I<must> be >= C<0>)
663	allows libev to delay invocation of I/O and timer/periodic callbacks to	702	allows libev to delay invocation of I/O and timer/periodic callbacks
664	increase efficiency of loop iterations.	703	to increase efficiency of loop iterations (or to increase power-saving
		704	opportunities).
665		705
666	The background is that sometimes your program runs just fast enough to	706	The background is that sometimes your program runs just fast enough to
667	handle one (or very few) event(s) per loop iteration. While this makes	707	handle one (or very few) event(s) per loop iteration. While this makes
668	the program responsive, it also wastes a lot of CPU time to poll for new	708	the program responsive, it also wastes a lot of CPU time to poll for new
669	events, especially with backends like C<select ()> which have a high	709	events, especially with backends like C<select ()> which have a high
…		…
679	to spend more time collecting timeouts, at the expense of increased	719	to spend more time collecting timeouts, at the expense of increased
680	latency (the watcher callback will be called later). C<ev_io> watchers	720	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	721	will not be affected. Setting this to a non-null value will not introduce
682	any overhead in libev.	722	any overhead in libev.
683		723
684	Many (busy) programs can usually benefit by setting the io collect	724	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	725	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	726	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>,	727	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.	728	as this approaches the timing granularity of most systems.
		729
		730	Setting the I<timeout collect interval> can improve the opportunity for
		731	saving power, as the program will "bundle" timer callback invocations that
		732	are "near" in time together, by delaying some, thus reducing the number of
		733	times the process sleeps and wakes up again. Another useful technique to
		734	reduce iterations/wake-ups is to use C<ev_periodic> watchers and make sure
		735	they fire on, say, one-second boundaries only.
		736
		737	=item ev_loop_verify (loop)
		738
		739	This function only does something when C<EV_VERIFY> support has been
		740	compiled in. It tries to go through all internal structures and checks
		741	them for validity. If anything is found to be inconsistent, it will print
		742	an error message to standard error and call C<abort ()>.
		743
		744	This can be used to catch bugs inside libev itself: under normal
		745	circumstances, this function will never abort as of course libev keeps its
		746	data structures consistent.
689		747
690	=back	748	=back
691		749
692		750
693	=head1 ANATOMY OF A WATCHER	751	=head1 ANATOMY OF A WATCHER
694		752
695	A watcher is a structure that you create and register to record your	753	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	754	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:	755	become readable, you would create an C<ev_io> watcher for that:
698		756
699	static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)	757	static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)
700	{	758	{
701	ev_io_stop (w);	759	ev_io_stop (w);
702	ev_unloop (loop, EVUNLOOP_ALL);	760	ev_unloop (loop, EVUNLOOP_ALL);
703	}	761	}
704		762
705	struct ev_loop *loop = ev_default_loop (0);	763	struct ev_loop *loop = ev_default_loop (0);
706	struct ev_io stdin_watcher;	764	struct ev_io stdin_watcher;
707	ev_init (&stdin_watcher, my_cb);	765	ev_init (&stdin_watcher, my_cb);
708	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);	766	ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ);
709	ev_io_start (loop, &stdin_watcher);	767	ev_io_start (loop, &stdin_watcher);
710	ev_loop (loop, 0);	768	ev_loop (loop, 0);
711		769
712	As you can see, you are responsible for allocating the memory for your	770	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,	771	watcher structures (and it is usually a bad idea to do this on the stack,
714	although this can sometimes be quite valid).	772	although this can sometimes be quite valid).
715		773
716	Each watcher structure must be initialised by a call to C<ev_init	774	Each watcher structure must be initialised by a call to C<ev_init
717	(watcher *, callback)>, which expects a callback to be provided. This	775	(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	776	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	777	watchers, each time the event loop detects that the file descriptor given
720	is readable and/or writable).	778	is readable and/or writable).
721		779
722	Each watcher type has its own C<< ev_<type>_set (watcher *, ...) >> macro	780	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	781	with arguments specific to this watcher type. There is also a macro
…		…
799		857
800	The given async watcher has been asynchronously notified (see C<ev_async>).	858	The given async watcher has been asynchronously notified (see C<ev_async>).
801		859
802	=item C<EV_ERROR>	860	=item C<EV_ERROR>
803		861
804	An unspecified error has occured, the watcher has been stopped. This might	862	An unspecified error has occurred, the watcher has been stopped. This might
805	happen because the watcher could not be properly started because libev	863	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	864	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	865	problem. You best act on it by reporting the problem and somehow coping
808	with the watcher being stopped.	866	with the watcher being stopped.
809		867
810	Libev will usually signal a few "dummy" events together with an error,	868	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	869	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	870	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	871	with the error from read() or write(). This will not work in multi-threaded
814	programs, though, so beware.	872	programs, though, so beware.
815		873
816	=back	874	=back
817		875
818	=head2 GENERIC WATCHER FUNCTIONS	876	=head2 GENERIC WATCHER FUNCTIONS
…		…
848	Although some watcher types do not have type-specific arguments	906	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.	907	(e.g. C<ev_prepare>) you still need to call its C<set> macro.
850		908
851	=item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args])	909	=item C<ev_TYPE_init> (ev_TYPE *watcher, callback, [args])
852		910
853	This convinience macro rolls both C<ev_init> and C<ev_TYPE_set> macro	911	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	912	calls into a single call. This is the most convenient method to initialise
855	a watcher. The same limitations apply, of course.	913	a watcher. The same limitations apply, of course.
856		914
857	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)	915	=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher)
858		916
859	Starts (activates) the given watcher. Only active watchers will receive	917	Starts (activates) the given watcher. Only active watchers will receive
…		…
942	to associate arbitrary data with your watcher. If you need more data and	1000	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	1001	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	1002	member, you can also "subclass" the watcher type and provide your own
945	data:	1003	data:
946		1004
947	struct my_io	1005	struct my_io
948	{	1006	{
949	struct ev_io io;	1007	struct ev_io io;
950	int otherfd;	1008	int otherfd;
951	void *somedata;	1009	void *somedata;
952	struct whatever *mostinteresting;	1010	struct whatever *mostinteresting;
953	}	1011	}
954		1012
955	And since your callback will be called with a pointer to the watcher, you	1013	And since your callback will be called with a pointer to the watcher, you
956	can cast it back to your own type:	1014	can cast it back to your own type:
957		1015
958	static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents)	1016	static void my_cb (struct ev_loop *loop, struct ev_io *w_, int revents)
959	{	1017	{
960	struct my_io *w = (struct my_io *)w_;	1018	struct my_io *w = (struct my_io *)w_;
961	...	1019	...
962	}	1020	}
963		1021
964	More interesting and less C-conformant ways of casting your callback type	1022	More interesting and less C-conformant ways of casting your callback type
965	instead have been omitted.	1023	instead have been omitted.
966		1024
967	Another common scenario is having some data structure with multiple	1025	Another common scenario is having some data structure with multiple
968	watchers:	1026	watchers:
969		1027
970	struct my_biggy	1028	struct my_biggy
971	{	1029	{
972	int some_data;	1030	int some_data;
973	ev_timer t1;	1031	ev_timer t1;
974	ev_timer t2;	1032	ev_timer t2;
975	}	1033	}
976		1034
977	In this case getting the pointer to C<my_biggy> is a bit more complicated,	1035	In this case getting the pointer to C<my_biggy> is a bit more complicated,
978	you need to use C<offsetof>:	1036	you need to use C<offsetof>:
979		1037
980	#include <stddef.h>	1038	#include <stddef.h>
981		1039
982	static void	1040	static void
983	t1_cb (EV_P_ struct ev_timer *w, int revents)	1041	t1_cb (EV_P_ struct ev_timer *w, int revents)
984	{	1042	{
985	struct my_biggy big = (struct my_biggy *	1043	struct my_biggy big = (struct my_biggy *
986	(((char *)w) - offsetof (struct my_biggy, t1));	1044	(((char *)w) - offsetof (struct my_biggy, t1));
987	}	1045	}
988		1046
989	static void	1047	static void
990	t2_cb (EV_P_ struct ev_timer *w, int revents)	1048	t2_cb (EV_P_ struct ev_timer *w, int revents)
991	{	1049	{
992	struct my_biggy big = (struct my_biggy *	1050	struct my_biggy big = (struct my_biggy *
993	(((char *)w) - offsetof (struct my_biggy, t2));	1051	(((char *)w) - offsetof (struct my_biggy, t2));
994	}	1052	}
995		1053
996		1054
997	=head1 WATCHER TYPES	1055	=head1 WATCHER TYPES
998		1056
999	This section describes each watcher in detail, but will not repeat	1057	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	1086	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	1087	(at the time of this writing, this includes only C<EVBACKEND_SELECT> and
1030	C<EVBACKEND_POLL>).	1088	C<EVBACKEND_POLL>).
1031		1089
1032	Another thing you have to watch out for is that it is quite easy to	1090	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	1091	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	1092	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	1093	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	1094	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	1095	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	1096	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.	1097	C<EAGAIN> is far preferable to a program hanging until some data arrives.
1040		1098
1041	If you cannot run the fd in non-blocking mode (for example you should not	1099	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	1100	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	1101	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	1102	such as poll (fortunately in our Xlib example, Xlib already does this on
1045	its own, so its quite safe to use).	1103	its own, so its quite safe to use).
1046		1104
1047	=head3 The special problem of disappearing file descriptors	1105	=head3 The special problem of disappearing file descriptors
…		…
1088	C<EVBACKEND_POLL>.	1146	C<EVBACKEND_POLL>.
1089		1147
1090	=head3 The special problem of SIGPIPE	1148	=head3 The special problem of SIGPIPE
1091		1149
1092	While not really specific to libev, it is easy to forget about SIGPIPE:	1150	While not really specific to libev, it is easy to forget about SIGPIPE:
1093	when reading from a pipe whose other end has been closed, your program	1151	when writing to a pipe whose other end has been closed, your program gets
1094	gets send a SIGPIPE, which, by default, aborts your program. For most	1152	send a SIGPIPE, which, by default, aborts your program. For most programs
1095	programs this is sensible behaviour, for daemons, this is usually	1153	this is sensible behaviour, for daemons, this is usually undesirable.
1096	undesirable.
1097		1154
1098	So when you encounter spurious, unexplained daemon exits, make sure you	1155	So when you encounter spurious, unexplained daemon exits, make sure you
1099	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon	1156	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon
1100	somewhere, as that would have given you a big clue).	1157	somewhere, as that would have given you a big clue).
1101		1158
…		…
1107	=item ev_io_init (ev_io *, callback, int fd, int events)	1164	=item ev_io_init (ev_io *, callback, int fd, int events)
1108		1165
1109	=item ev_io_set (ev_io *, int fd, int events)	1166	=item ev_io_set (ev_io *, int fd, int events)
1110		1167
1111	Configures an C<ev_io> watcher. The C<fd> is the file descriptor to	1168	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	1169	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.	1170	C<EV_READ | EV_WRITE> to receive the given events.
1114		1171
1115	=item int fd [read-only]	1172	=item int fd [read-only]
1116		1173
1117	The file descriptor being watched.	1174	The file descriptor being watched.
…		…
1126		1183
1127	Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well	1184	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	1185	readable, but only once. Since it is likely line-buffered, you could
1129	attempt to read a whole line in the callback.	1186	attempt to read a whole line in the callback.
1130		1187
1131	static void	1188	static void
1132	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1189	stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1133	{	1190	{
1134	ev_io_stop (loop, w);	1191	ev_io_stop (loop, w);
1135	.. read from stdin here (or from w->fd) and haqndle any I/O errors	1192	.. read from stdin here (or from w->fd) and haqndle any I/O errors
1136	}	1193	}
1137		1194
1138	...	1195	...
1139	struct ev_loop *loop = ev_default_init (0);	1196	struct ev_loop *loop = ev_default_init (0);
1140	struct ev_io stdin_readable;	1197	struct ev_io stdin_readable;
1141	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);	1198	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
1142	ev_io_start (loop, &stdin_readable);	1199	ev_io_start (loop, &stdin_readable);
1143	ev_loop (loop, 0);	1200	ev_loop (loop, 0);
1144		1201
1145		1202
1146	=head2 C<ev_timer> - relative and optionally repeating timeouts	1203	=head2 C<ev_timer> - relative and optionally repeating timeouts
1147		1204
1148	Timer watchers are simple relative timers that generate an event after a	1205	Timer watchers are simple relative timers that generate an event after a
1149	given time, and optionally repeating in regular intervals after that.	1206	given time, and optionally repeating in regular intervals after that.
1150		1207
1151	The timers are based on real time, that is, if you register an event that	1208	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	1209	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	1210	year, it will still time out after (roughly) and hour. "Roughly" because
1154	detecting time jumps is hard, and some inaccuracies are unavoidable (the	1211	detecting time jumps is hard, and some inaccuracies are unavoidable (the
1155	monotonic clock option helps a lot here).	1212	monotonic clock option helps a lot here).
		1213
		1214	The callback is guaranteed to be invoked only after its timeout has passed,
		1215	but if multiple timers become ready during the same loop iteration then
		1216	order of execution is undefined.
		1217
		1218	=head3 The special problem of time updates
		1219
		1220	Establishing the current time is a costly operation (it usually takes at
		1221	least two system calls): EV therefore updates its idea of the current
		1222	time only before and after C<ev_loop> polls for new events, which causes
		1223	a growing difference between C<ev_now ()> and C<ev_time ()> when handling
		1224	lots of events.
1156		1225
1157	The relative timeouts are calculated relative to the C<ev_now ()>	1226	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	1227	time. This is usually the right thing as this timestamp refers to the time
1159	of the event triggering whatever timeout you are modifying/starting. If	1228	of the event triggering whatever timeout you are modifying/starting. If
1160	you suspect event processing to be delayed and you I<need> to base the timeout	1229	you suspect event processing to be delayed and you I<need> to base the
1161	on the current time, use something like this to adjust for this:	1230	timeout on the current time, use something like this to adjust for this:
1162		1231
1163	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);	1232	ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);
1164		1233
1165	The callback is guarenteed to be invoked only when its timeout has passed,	1234	If the event loop is suspended for a long time, one can also force an
1166	but if multiple timers become ready during the same loop iteration then	1235	update of the time returned by C<ev_now ()> by calling C<ev_now_update
1167	order of execution is undefined.	1236	()>.
1168		1237
1169	=head3 Watcher-Specific Functions and Data Members	1238	=head3 Watcher-Specific Functions and Data Members
1170		1239
1171	=over 4	1240	=over 4
1172		1241
1173	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)	1242	=item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)
1174		1243
1175	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)	1244	=item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)
1176		1245
1177	Configure the timer to trigger after C<after> seconds. If C<repeat> is	1246	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	1247	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	1248	reached. If it is positive, then the timer will automatically be
1180	later, again, and again, until stopped manually.	1249	configured to trigger again C<repeat> seconds later, again, and again,
		1250	until stopped manually.
1181		1251
1182	The timer itself will do a best-effort at avoiding drift, that is, if you	1252	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	1253	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	1254	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	1255	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.	1256	do stuff) the timer will not fire more than once per event loop iteration.
1187		1257
1188	=item ev_timer_again (loop, ev_timer *)	1258	=item ev_timer_again (loop, ev_timer *)
1189		1259
1190	This will act as if the timer timed out and restart it again if it is	1260	This will act as if the timer timed out and restart it again if it is
1191	repeating. The exact semantics are:	1261	repeating. The exact semantics are:
1192		1262
1193	If the timer is pending, its pending status is cleared.	1263	If the timer is pending, its pending status is cleared.
1194		1264
1195	If the timer is started but nonrepeating, stop it (as if it timed out).	1265	If the timer is started but non-repeating, stop it (as if it timed out).
1196		1266
1197	If the timer is repeating, either start it if necessary (with the	1267	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.	1268	C<repeat> value), or reset the running timer to the C<repeat> value.
1199		1269
1200	This sounds a bit complicated, but here is a useful and typical	1270	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	1271	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	1272	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	1273	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	1274	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	1275	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	1276	you go into an idle state where you do not expect data to travel on the
…		…
1232		1302
1233	=head3 Examples	1303	=head3 Examples
1234		1304
1235	Example: Create a timer that fires after 60 seconds.	1305	Example: Create a timer that fires after 60 seconds.
1236		1306
1237	static void	1307	static void
1238	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1308	one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1239	{	1309	{
1240	.. one minute over, w is actually stopped right here	1310	.. one minute over, w is actually stopped right here
1241	}	1311	}
1242		1312
1243	struct ev_timer mytimer;	1313	struct ev_timer mytimer;
1244	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1314	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
1245	ev_timer_start (loop, &mytimer);	1315	ev_timer_start (loop, &mytimer);
1246		1316
1247	Example: Create a timeout timer that times out after 10 seconds of	1317	Example: Create a timeout timer that times out after 10 seconds of
1248	inactivity.	1318	inactivity.
1249		1319
1250	static void	1320	static void
1251	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)	1321	timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1252	{	1322	{
1253	.. ten seconds without any activity	1323	.. ten seconds without any activity
1254	}	1324	}
1255		1325
1256	struct ev_timer mytimer;	1326	struct ev_timer mytimer;
1257	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */	1327	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
1258	ev_timer_again (&mytimer); /* start timer */	1328	ev_timer_again (&mytimer); /* start timer */
1259	ev_loop (loop, 0);	1329	ev_loop (loop, 0);
1260		1330
1261	// and in some piece of code that gets executed on any "activity":	1331	// and in some piece of code that gets executed on any "activity":
1262	// reset the timeout to start ticking again at 10 seconds	1332	// reset the timeout to start ticking again at 10 seconds
1263	ev_timer_again (&mytimer);	1333	ev_timer_again (&mytimer);
1264		1334
1265		1335
1266	=head2 C<ev_periodic> - to cron or not to cron?	1336	=head2 C<ev_periodic> - to cron or not to cron?
1267		1337
1268	Periodic watchers are also timers of a kind, but they are very versatile	1338	Periodic watchers are also timers of a kind, but they are very versatile
1269	(and unfortunately a bit complex).	1339	(and unfortunately a bit complex).
1270		1340
1271	Unlike C<ev_timer>'s, they are not based on real time (or relative time)	1341	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	1342	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	1343	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 ()	1344	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	1345	+ 10.>, that is, an absolute time not a delay) and then reset your system
		1346	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	1347	to trigger the event (unlike an C<ev_timer>, which would still trigger
1277	roughly 10 seconds later).	1348	roughly 10 seconds later as it uses a relative timeout).
1278		1349
1279	They can also be used to implement vastly more complex timers, such as	1350	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,	1351	such as triggering an event on each "midnight, local time", or other
1281	rules.	1352	complicated, rules.
1282		1353
1283	As with timers, the callback is guarenteed to be invoked only when the	1354	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	1355	time (C<at>) has passed, but if multiple periodic timers become ready
1285	during the same loop iteration then order of execution is undefined.	1356	during the same loop iteration then order of execution is undefined.
1286		1357
1287	=head3 Watcher-Specific Functions and Data Members	1358	=head3 Watcher-Specific Functions and Data Members
1288		1359
1289	=over 4	1360	=over 4
…		…
1297		1368
1298	=over 4	1369	=over 4
1299		1370
1300	=item * absolute timer (at = time, interval = reschedule_cb = 0)	1371	=item * absolute timer (at = time, interval = reschedule_cb = 0)
1301		1372
1302	In this configuration the watcher triggers an event at the wallclock time	1373	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,	1374	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	1375	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.	1376	run when the system time reaches or surpasses this time.
1306		1377
1307	=item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)	1378	=item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)
1308		1379
1309	In this mode the watcher will always be scheduled to time out at the next	1380	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)	1381	C<at + N * interval> time (for some integer N, which can also be negative)
1311	and then repeat, regardless of any time jumps.	1382	and then repeat, regardless of any time jumps.
1312		1383
1313	This can be used to create timers that do not drift with respect to system	1384	This can be used to create timers that do not drift with respect to system
1314	time:	1385	time, for example, here is a C<ev_periodic> that triggers each hour, on
		1386	the hour:
1315		1387
1316	ev_periodic_set (&periodic, 0., 3600., 0);	1388	ev_periodic_set (&periodic, 0., 3600., 0);
1317		1389
1318	This doesn't mean there will always be 3600 seconds in between triggers,	1390	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	1391	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	1392	full hour (UTC), or more correctly, when the system time is evenly divisible
1321	by 3600.	1393	by 3600.
1322		1394
1323	Another way to think about it (for the mathematically inclined) is that	1395	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	1396	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.	1397	time where C<time = at (mod interval)>, regardless of any time jumps.
1326		1398
1327	For numerical stability it is preferable that the C<at> value is near	1399	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	1400	C<ev_now ()> (the current time), but there is no range requirement for
1329	this value.	1401	this value, and in fact is often specified as zero.
		1402
		1403	Note also that there is an upper limit to how often a timer can fire (CPU
		1404	speed for example), so if C<interval> is very small then timing stability
		1405	will of course deteriorate. Libev itself tries to be exact to be about one
		1406	millisecond (if the OS supports it and the machine is fast enough).
1330		1407
1331	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)	1408	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)
1332		1409
1333	In this mode the values for C<interval> and C<at> are both being	1410	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	1411	ignored. Instead, each time the periodic watcher gets scheduled, the
1335	reschedule callback will be called with the watcher as first, and the	1412	reschedule callback will be called with the watcher as first, and the
1336	current time as second argument.	1413	current time as second argument.
1337		1414
1338	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,	1415	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,	1416	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		1417
		1418	If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop
		1419	it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the
		1420	only event loop modification you are allowed to do).
		1421
1343	Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w,	1422	The callback prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic
1344	ev_tstamp now)>, e.g.:	1423	*w, ev_tstamp now)>, e.g.:
1345		1424
1346	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	1425	static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
1347	{	1426	{
1348	return now + 60.;	1427	return now + 60.;
1349	}	1428	}
…		…
1351	It must return the next time to trigger, based on the passed time value	1430	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	1431	(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	1432	will usually be called just before the callback will be triggered, but
1354	might be called at other times, too.	1433	might be called at other times, too.
1355		1434
1356	NOTE: I<< This callback must always return a time that is later than the	1435	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.	1436	equal to the passed C<now> value >>.
1358		1437
1359	This can be used to create very complex timers, such as a timer that	1438	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	1439	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	1440	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	1441	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).	1442	reason I omitted it as an example).
1364		1443
1365	=back	1444	=back
…		…
1369	Simply stops and restarts the periodic watcher again. This is only useful	1448	Simply stops and restarts the periodic watcher again. This is only useful
1370	when you changed some parameters or the reschedule callback would return	1449	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	1450	a different time than the last time it was called (e.g. in a crond like
1372	program when the crontabs have changed).	1451	program when the crontabs have changed).
1373		1452
		1453	=item ev_tstamp ev_periodic_at (ev_periodic *)
		1454
		1455	When active, returns the absolute time that the watcher is supposed to
		1456	trigger next.
		1457
1374	=item ev_tstamp offset [read-write]	1458	=item ev_tstamp offset [read-write]
1375		1459
1376	When repeating, this contains the offset value, otherwise this is the	1460	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>).	1461	absolute point in time (the C<at> value passed to C<ev_periodic_set>).
1378		1462
…		…
1389		1473
1390	The current reschedule callback, or C<0>, if this functionality is	1474	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	1475	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.	1476	the periodic timer fires or C<ev_periodic_again> is being called.
1393		1477
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	1478	=back
1400		1479
1401	=head3 Examples	1480	=head3 Examples
1402		1481
1403	Example: Call a callback every hour, or, more precisely, whenever the	1482	Example: Call a callback every hour, or, more precisely, whenever the
1404	system clock is divisible by 3600. The callback invocation times have	1483	system clock is divisible by 3600. The callback invocation times have
1405	potentially a lot of jittering, but good long-term stability.	1484	potentially a lot of jitter, but good long-term stability.
1406		1485
1407	static void	1486	static void
1408	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)	1487	clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1409	{	1488	{
1410	... its now a full hour (UTC, or TAI or whatever your clock follows)	1489	... its now a full hour (UTC, or TAI or whatever your clock follows)
1411	}	1490	}
1412		1491
1413	struct ev_periodic hourly_tick;	1492	struct ev_periodic hourly_tick;
1414	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1493	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1415	ev_periodic_start (loop, &hourly_tick);	1494	ev_periodic_start (loop, &hourly_tick);
1416		1495
1417	Example: The same as above, but use a reschedule callback to do it:	1496	Example: The same as above, but use a reschedule callback to do it:
1418		1497
1419	#include <math.h>	1498	#include <math.h>
1420		1499
1421	static ev_tstamp	1500	static ev_tstamp
1422	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1501	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
1423	{	1502	{
1424	return fmod (now, 3600.) + 3600.;	1503	return fmod (now, 3600.) + 3600.;
1425	}	1504	}
1426		1505
1427	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1506	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1428		1507
1429	Example: Call a callback every hour, starting now:	1508	Example: Call a callback every hour, starting now:
1430		1509
1431	struct ev_periodic hourly_tick;	1510	struct ev_periodic hourly_tick;
1432	ev_periodic_init (&hourly_tick, clock_cb,	1511	ev_periodic_init (&hourly_tick, clock_cb,
1433	fmod (ev_now (loop), 3600.), 3600., 0);	1512	fmod (ev_now (loop), 3600.), 3600., 0);
1434	ev_periodic_start (loop, &hourly_tick);	1513	ev_periodic_start (loop, &hourly_tick);
1435		1514
1436		1515
1437	=head2 C<ev_signal> - signal me when a signal gets signalled!	1516	=head2 C<ev_signal> - signal me when a signal gets signalled!
1438		1517
1439	Signal watchers will trigger an event when the process receives a specific	1518	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	1526	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	1527	watcher for a signal is stopped libev will reset the signal handler to
1449	SIG_DFL (regardless of what it was set to before).	1528	SIG_DFL (regardless of what it was set to before).
1450		1529
1451	If possible and supported, libev will install its handlers with	1530	If possible and supported, libev will install its handlers with
1452	C<SA_RESTART> behaviour enabled, so syscalls should not be unduly	1531	C<SA_RESTART> behaviour enabled, so system calls should not be unduly
1453	interrupted. If you have a problem with syscalls getting interrupted by	1532	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	1533	signals you can block all signals in an C<ev_check> watcher and unblock
1455	them in an C<ev_prepare> watcher.	1534	them in an C<ev_prepare> watcher.
1456		1535
1457	=head3 Watcher-Specific Functions and Data Members	1536	=head3 Watcher-Specific Functions and Data Members
1458		1537
…		…
1473		1552
1474	=head3 Examples	1553	=head3 Examples
1475		1554
1476	Example: Try to exit cleanly on SIGINT and SIGTERM.	1555	Example: Try to exit cleanly on SIGINT and SIGTERM.
1477		1556
1478	static void	1557	static void
1479	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)	1558	sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1480	{	1559	{
1481	ev_unloop (loop, EVUNLOOP_ALL);	1560	ev_unloop (loop, EVUNLOOP_ALL);
1482	}	1561	}
1483		1562
1484	struct ev_signal signal_watcher;	1563	struct ev_signal signal_watcher;
1485	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1564	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1486	ev_signal_start (loop, &sigint_cb);	1565	ev_signal_start (loop, &sigint_cb);
1487		1566
1488		1567
1489	=head2 C<ev_child> - watch out for process status changes	1568	=head2 C<ev_child> - watch out for process status changes
1490		1569
1491	Child watchers trigger when your process receives a SIGCHLD in response to	1570	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	1572	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	1573	forked (which implies it might have already exited), as long as the event
1495	loop isn't entered (or is continued from a watcher).	1574	loop isn't entered (or is continued from a watcher).
1496		1575
1497	Only the default event loop is capable of handling signals, and therefore	1576	Only the default event loop is capable of handling signals, and therefore
1498	you can only rgeister child watchers in the default event loop.	1577	you can only register child watchers in the default event loop.
1499		1578
1500	=head3 Process Interaction	1579	=head3 Process Interaction
1501		1580
1502	Libev grabs C<SIGCHLD> as soon as the default event loop is	1581	Libev grabs C<SIGCHLD> as soon as the default event loop is
1503	initialised. This is necessary to guarantee proper behaviour even if	1582	initialised. This is necessary to guarantee proper behaviour even if
1504	the first child watcher is started after the child exits. The occurance	1583	the first child watcher is started after the child exits. The occurrence
1505	of C<SIGCHLD> is recorded asynchronously, but child reaping is done	1584	of C<SIGCHLD> is recorded asynchronously, but child reaping is done
1506	synchronously as part of the event loop processing. Libev always reaps all	1585	synchronously as part of the event loop processing. Libev always reaps all
1507	children, even ones not watched.	1586	children, even ones not watched.
1508		1587
1509	=head3 Overriding the Built-In Processing	1588	=head3 Overriding the Built-In Processing
…		…
1513	handler, you can override it easily by installing your own handler for	1592	handler, you can override it easily by installing your own handler for
1514	C<SIGCHLD> after initialising the default loop, and making sure the	1593	C<SIGCHLD> after initialising the default loop, and making sure the
1515	default loop never gets destroyed. You are encouraged, however, to use an	1594	default loop never gets destroyed. You are encouraged, however, to use an
1516	event-based approach to child reaping and thus use libev's support for	1595	event-based approach to child reaping and thus use libev's support for
1517	that, so other libev users can use C<ev_child> watchers freely.	1596	that, so other libev users can use C<ev_child> watchers freely.
		1597
		1598	=head3 Stopping the Child Watcher
		1599
		1600	Currently, the child watcher never gets stopped, even when the
		1601	child terminates, so normally one needs to stop the watcher in the
		1602	callback. Future versions of libev might stop the watcher automatically
		1603	when a child exit is detected.
1518		1604
1519	=head3 Watcher-Specific Functions and Data Members	1605	=head3 Watcher-Specific Functions and Data Members
1520		1606
1521	=over 4	1607	=over 4
1522		1608
…		…
1551	=head3 Examples	1637	=head3 Examples
1552		1638
1553	Example: C<fork()> a new process and install a child handler to wait for	1639	Example: C<fork()> a new process and install a child handler to wait for
1554	its completion.	1640	its completion.
1555		1641
1556	ev_child cw;	1642	ev_child cw;
1557		1643
1558	static void	1644	static void
1559	child_cb (EV_P_ struct ev_child *w, int revents)	1645	child_cb (EV_P_ struct ev_child *w, int revents)
1560	{	1646	{
1561	ev_child_stop (EV_A_ w);	1647	ev_child_stop (EV_A_ w);
1562	printf ("process %d exited with status %x\n", w->rpid, w->rstatus);	1648	printf ("process %d exited with status %x\n", w->rpid, w->rstatus);
1563	}	1649	}
1564		1650
1565	pid_t pid = fork ();	1651	pid_t pid = fork ();
1566		1652
1567	if (pid < 0)	1653	if (pid < 0)
1568	// error	1654	// error
1569	else if (pid == 0)	1655	else if (pid == 0)
1570	{	1656	{
1571	// the forked child executes here	1657	// the forked child executes here
1572	exit (1);	1658	exit (1);
1573	}	1659	}
1574	else	1660	else
1575	{	1661	{
1576	ev_child_init (&cw, child_cb, pid, 0);	1662	ev_child_init (&cw, child_cb, pid, 0);
1577	ev_child_start (EV_DEFAULT_ &cw);	1663	ev_child_start (EV_DEFAULT_ &cw);
1578	}	1664	}
1579		1665
1580		1666
1581	=head2 C<ev_stat> - did the file attributes just change?	1667	=head2 C<ev_stat> - did the file attributes just change?
1582		1668
1583	This watches a filesystem path for attribute changes. That is, it calls	1669	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	1670	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.	1671	compared to the last time, invoking the callback if it did.
1586		1672
1587	The path does not need to exist: changing from "path exists" to "path does	1673	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	1674	not exist" is a status change like any other. The condition "path does
…		…
1606	as even with OS-supported change notifications, this can be	1692	as even with OS-supported change notifications, this can be
1607	resource-intensive.	1693	resource-intensive.
1608		1694
1609	At the time of this writing, only the Linux inotify interface is	1695	At the time of this writing, only the Linux inotify interface is
1610	implemented (implementing kqueue support is left as an exercise for the	1696	implemented (implementing kqueue support is left as an exercise for the
		1697	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	1698	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	1699	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	1700	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	1701	but changes are usually detected immediately, and if the file exists there
1615	polling.	1702	will be no polling.
1616		1703
1617	=head3 ABI Issues (Largefile Support)	1704	=head3 ABI Issues (Largefile Support)
1618		1705
1619	Libev by default (unless the user overrides this) uses the default	1706	Libev by default (unless the user overrides this) uses the default
1620	compilation environment, which means that on systems with optionally	1707	compilation environment, which means that on systems with large file
1621	disabled large file support, you get the 32 bit version of the stat	1708	support disabled by default, you get the 32 bit version of the stat
1622	structure. When using the library from programs that change the ABI to	1709	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	1710	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	1711	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	1712	obviously the case with any flags that change the ABI, but the problem is
1626	most noticably with ev_stat and largefile support.	1713	most noticeably disabled with ev_stat and large file support.
		1714
		1715	The solution for this is to lobby your distribution maker to make large
		1716	file interfaces available by default (as e.g. FreeBSD does) and not
		1717	optional. Libev cannot simply switch on large file support because it has
		1718	to exchange stat structures with application programs compiled using the
		1719	default compilation environment.
1627		1720
1628	=head3 Inotify	1721	=head3 Inotify
1629		1722
1630	When C<inotify (7)> support has been compiled into libev (generally only	1723	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	1724	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	1725	change detection where possible. The inotify descriptor will be created lazily
1633	when the first C<ev_stat> watcher is being started.	1726	when the first C<ev_stat> watcher is being started.
1634		1727
1635	Inotify presense does not change the semantics of C<ev_stat> watchers	1728	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	1729	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	1730	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.	1731	there are many cases where libev has to resort to regular C<stat> polling.
1639		1732
1640	(There is no support for kqueue, as apparently it cannot be used to	1733	(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	1734	implement this functionality, due to the requirement of having a file
1642	descriptor open on the object at all times).	1735	descriptor open on the object at all times).
1643		1736
1644	=head3 The special problem of stat time resolution	1737	=head3 The special problem of stat time resolution
1645		1738
1646	The C<stat ()> syscall only supports full-second resolution portably, and	1739	The C<stat ()> system call only supports full-second resolution portably, and
1647	even on systems where the resolution is higher, many filesystems still	1740	even on systems where the resolution is higher, many file systems still
1648	only support whole seconds.	1741	only support whole seconds.
1649		1742
1650	That means that, if the time is the only thing that changes, you might	1743	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	1744	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	1745	calls your callback, which does something. When there is another update
1653	the same second, C<ev_stat> will be unable to detect it.	1746	within the same second, C<ev_stat> will be unable to detect it as the stat
		1747	data does not change.
1654		1748
1655	The solution to this is to delay acting on a change for a second (or till	1749	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>	1750	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>	1751	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	1752	ev_timer_again (loop, w)>).
1659	systems.	1753
		1754	The C<.02> offset is added to work around small timing inconsistencies
		1755	of some operating systems (where the second counter of the current time
		1756	might be be delayed. One such system is the Linux kernel, where a call to
		1757	C<gettimeofday> might return a timestamp with a full second later than
		1758	a subsequent C<time> call - if the equivalent of C<time ()> is used to
		1759	update file times then there will be a small window where the kernel uses
		1760	the previous second to update file times but libev might already execute
		1761	the timer callback).
1660		1762
1661	=head3 Watcher-Specific Functions and Data Members	1763	=head3 Watcher-Specific Functions and Data Members
1662		1764
1663	=over 4	1765	=over 4
1664		1766
…		…
1670	C<path>. The C<interval> is a hint on how quickly a change is expected to	1772	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	1773	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	1774	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.	1775	path for as long as the watcher is active.
1674		1776
1675	The callback will be receive C<EV_STAT> when a change was detected,	1777	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	1778	to the attributes at the time the watcher was started (or the last change
1677	last change was detected).	1779	was detected).
1678		1780
1679	=item ev_stat_stat (loop, ev_stat *)	1781	=item ev_stat_stat (loop, ev_stat *)
1680		1782
1681	Updates the stat buffer immediately with new values. If you change the	1783	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	1784	watched path in your callback, you could call this function to avoid
1683	detecting this change (while introducing a race condition). Can also be	1785	detecting this change (while introducing a race condition if you are not
1684	useful simply to find out the new values.	1786	the only one changing the path). Can also be useful simply to find out the
		1787	new values.
1685		1788
1686	=item ev_statdata attr [read-only]	1789	=item ev_statdata attr [read-only]
1687		1790
1688	The most-recently detected attributes of the file. Although the type is of	1791	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	1792	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	1793	suitable for your system, but you can only rely on the POSIX-standardised
		1794	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.	1795	some error while C<stat>ing the file.
1692		1796
1693	=item ev_statdata prev [read-only]	1797	=item ev_statdata prev [read-only]
1694		1798
1695	The previous attributes of the file. The callback gets invoked whenever	1799	The previous attributes of the file. The callback gets invoked whenever
1696	C<prev> != C<attr>.	1800	C<prev> != C<attr>, or, more precisely, one or more of these members
		1801	differ: C<st_dev>, C<st_ino>, C<st_mode>, C<st_nlink>, C<st_uid>,
		1802	C<st_gid>, C<st_rdev>, C<st_size>, C<st_atime>, C<st_mtime>, C<st_ctime>.
1697		1803
1698	=item ev_tstamp interval [read-only]	1804	=item ev_tstamp interval [read-only]
1699		1805
1700	The specified interval.	1806	The specified interval.
1701		1807
1702	=item const char *path [read-only]	1808	=item const char *path [read-only]
1703		1809
1704	The filesystem path that is being watched.	1810	The file system path that is being watched.
1705		1811
1706	=back	1812	=back
1707		1813
1708	=head3 Examples	1814	=head3 Examples
1709		1815
1710	Example: Watch C</etc/passwd> for attribute changes.	1816	Example: Watch C</etc/passwd> for attribute changes.
1711		1817
1712	static void	1818	static void
1713	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)	1819	passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
1714	{	1820	{
1715	/* /etc/passwd changed in some way */	1821	/* /etc/passwd changed in some way */
1716	if (w->attr.st_nlink)	1822	if (w->attr.st_nlink)
1717	{	1823	{
1718	printf ("passwd current size %ld\n", (long)w->attr.st_size);	1824	printf ("passwd current size %ld\n", (long)w->attr.st_size);
1719	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);	1825	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
1720	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);	1826	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
1721	}	1827	}
1722	else	1828	else
1723	/* you shalt not abuse printf for puts */	1829	/* you shalt not abuse printf for puts */
1724	puts ("wow, /etc/passwd is not there, expect problems. "	1830	puts ("wow, /etc/passwd is not there, expect problems. "
1725	"if this is windows, they already arrived\n");	1831	"if this is windows, they already arrived\n");
1726	}	1832	}
1727		1833
1728	...	1834	...
1729	ev_stat passwd;	1835	ev_stat passwd;
1730		1836
1731	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);	1837	ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.);
1732	ev_stat_start (loop, &passwd);	1838	ev_stat_start (loop, &passwd);
1733		1839
1734	Example: Like above, but additionally use a one-second delay so we do not	1840	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	1841	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	1842	one might do the work both on C<ev_stat> callback invocation I<and> on
1737	C<ev_timer> callback invocation).	1843	C<ev_timer> callback invocation).
1738		1844
1739	static ev_stat passwd;	1845	static ev_stat passwd;
1740	static ev_timer timer;	1846	static ev_timer timer;
1741		1847
1742	static void	1848	static void
1743	timer_cb (EV_P_ ev_timer *w, int revents)	1849	timer_cb (EV_P_ ev_timer *w, int revents)
1744	{	1850	{
1745	ev_timer_stop (EV_A_ w);	1851	ev_timer_stop (EV_A_ w);
1746		1852
1747	/* now it's one second after the most recent passwd change */	1853	/* now it's one second after the most recent passwd change */
1748	}	1854	}
1749		1855
1750	static void	1856	static void
1751	stat_cb (EV_P_ ev_stat *w, int revents)	1857	stat_cb (EV_P_ ev_stat *w, int revents)
1752	{	1858	{
1753	/* reset the one-second timer */	1859	/* reset the one-second timer */
1754	ev_timer_again (EV_A_ &timer);	1860	ev_timer_again (EV_A_ &timer);
1755	}	1861	}
1756		1862
1757	...	1863	...
1758	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);	1864	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);
1759	ev_stat_start (loop, &passwd);	1865	ev_stat_start (loop, &passwd);
1760	ev_timer_init (&timer, timer_cb, 0., 1.01);	1866	ev_timer_init (&timer, timer_cb, 0., 1.02);
1761		1867
1762		1868
1763	=head2 C<ev_idle> - when you've got nothing better to do...	1869	=head2 C<ev_idle> - when you've got nothing better to do...
1764		1870
1765	Idle watchers trigger events when no other events of the same or higher	1871	Idle watchers trigger events when no other events of the same or higher
…		…
1796	=head3 Examples	1902	=head3 Examples
1797		1903
1798	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the	1904	Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the
1799	callback, free it. Also, use no error checking, as usual.	1905	callback, free it. Also, use no error checking, as usual.
1800		1906
1801	static void	1907	static void
1802	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)	1908	idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1803	{	1909	{
1804	free (w);	1910	free (w);
1805	// now do something you wanted to do when the program has	1911	// now do something you wanted to do when the program has
1806	// no longer anything immediate to do.	1912	// no longer anything immediate to do.
1807	}	1913	}
1808		1914
1809	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));	1915	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
1810	ev_idle_init (idle_watcher, idle_cb);	1916	ev_idle_init (idle_watcher, idle_cb);
1811	ev_idle_start (loop, idle_cb);	1917	ev_idle_start (loop, idle_cb);
1812		1918
1813		1919
1814	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!	1920	=head2 C<ev_prepare> and C<ev_check> - customise your event loop!
1815		1921
1816	Prepare and check watchers are usually (but not always) used in tandem:	1922	Prepare and check watchers are usually (but not always) used in tandem:
…		…
1835		1941
1836	This is done by examining in each prepare call which file descriptors need	1942	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	1943	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	1944	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	1945	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	1946	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	1947	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,	1948	callbacks will never actually be called (but must be valid nevertheless,
1843	because you never know, you know?).	1949	because you never know, you know?).
1844		1950
1845	As another example, the Perl Coro module uses these hooks to integrate	1951	As another example, the Perl Coro module uses these hooks to integrate
…		…
1853		1959
1854	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)	1960	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	1961	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,	1962	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	1963	too) should not activate ("feed") events into libev. While libev fully
1858	supports this, they will be called before other C<ev_check> watchers	1964	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	1965	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	1966	(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	1967	state until their C<ev_check> watcher ran (always remind yourself to
1862	coexist peacefully with others).	1968	coexist peacefully with others).
1863		1969
…		…
1878	=head3 Examples	1984	=head3 Examples
1879		1985
1880	There are a number of principal ways to embed other event loops or modules	1986	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	1987	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	1988	(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>	1989	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	1990	Glib main context into libev, and finally, C<Glib::EV> embeds EV into the
1885	into the Glib event loop).	1991	Glib event loop).
1886		1992
1887	Method 1: Add IO watchers and a timeout watcher in a prepare handler,	1993	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	1994	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	1995	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	1996	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.	1997	the callbacks for the IO/timeout watchers might not have been called yet.
1892		1998
1893	static ev_io iow [nfd];	1999	static ev_io iow [nfd];
1894	static ev_timer tw;	2000	static ev_timer tw;
1895		2001
1896	static void	2002	static void
1897	io_cb (ev_loop *loop, ev_io *w, int revents)	2003	io_cb (ev_loop *loop, ev_io *w, int revents)
1898	{	2004	{
1899	}	2005	}
1900		2006
1901	// create io watchers for each fd and a timer before blocking	2007	// create io watchers for each fd and a timer before blocking
1902	static void	2008	static void
1903	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)	2009	adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1904	{	2010	{
1905	int timeout = 3600000;	2011	int timeout = 3600000;
1906	struct pollfd fds [nfd];	2012	struct pollfd fds [nfd];
1907	// actual code will need to loop here and realloc etc.	2013	// actual code will need to loop here and realloc etc.
1908	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	2014	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1909		2015
1910	/* the callback is illegal, but won't be called as we stop during check */	2016	/* the callback is illegal, but won't be called as we stop during check */
1911	ev_timer_init (&tw, 0, timeout * 1e-3);	2017	ev_timer_init (&tw, 0, timeout * 1e-3);
1912	ev_timer_start (loop, &tw);	2018	ev_timer_start (loop, &tw);
1913		2019
1914	// create one ev_io per pollfd	2020	// create one ev_io per pollfd
1915	for (int i = 0; i < nfd; ++i)	2021	for (int i = 0; i < nfd; ++i)
1916	{	2022	{
1917	ev_io_init (iow + i, io_cb, fds [i].fd,	2023	ev_io_init (iow + i, io_cb, fds [i].fd,
1918	((fds [i].events & POLLIN ? EV_READ : 0)	2024	((fds [i].events & POLLIN ? EV_READ : 0)
1919	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	2025	| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1920		2026
1921	fds [i].revents = 0;	2027	fds [i].revents = 0;
1922	ev_io_start (loop, iow + i);	2028	ev_io_start (loop, iow + i);
1923	}	2029	}
1924	}	2030	}
1925		2031
1926	// stop all watchers after blocking	2032	// stop all watchers after blocking
1927	static void	2033	static void
1928	adns_check_cb (ev_loop *loop, ev_check *w, int revents)	2034	adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1929	{	2035	{
1930	ev_timer_stop (loop, &tw);	2036	ev_timer_stop (loop, &tw);
1931		2037
1932	for (int i = 0; i < nfd; ++i)	2038	for (int i = 0; i < nfd; ++i)
1933	{	2039	{
1934	// set the relevant poll flags	2040	// set the relevant poll flags
1935	// could also call adns_processreadable etc. here	2041	// could also call adns_processreadable etc. here
1936	struct pollfd *fd = fds + i;	2042	struct pollfd *fd = fds + i;
1937	int revents = ev_clear_pending (iow + i);	2043	int revents = ev_clear_pending (iow + i);
1938	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;	2044	if (revents & EV_READ ) fd->revents |= fd->events & POLLIN;
1939	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;	2045	if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT;
1940		2046
1941	// now stop the watcher	2047	// now stop the watcher
1942	ev_io_stop (loop, iow + i);	2048	ev_io_stop (loop, iow + i);
1943	}	2049	}
1944		2050
1945	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	2051	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
1946	}	2052	}
1947		2053
1948	Method 2: This would be just like method 1, but you run C<adns_afterpoll>	2054	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.	2055	in the prepare watcher and would dispose of the check watcher.
1950		2056
1951	Method 3: If the module to be embedded supports explicit event	2057	Method 3: If the module to be embedded supports explicit event
1952	notification (adns does), you can also make use of the actual watcher	2058	notification (libadns does), you can also make use of the actual watcher
1953	callbacks, and only destroy/create the watchers in the prepare watcher.	2059	callbacks, and only destroy/create the watchers in the prepare watcher.
1954		2060
1955	static void	2061	static void
1956	timer_cb (EV_P_ ev_timer *w, int revents)	2062	timer_cb (EV_P_ ev_timer *w, int revents)
1957	{	2063	{
1958	adns_state ads = (adns_state)w->data;	2064	adns_state ads = (adns_state)w->data;
1959	update_now (EV_A);	2065	update_now (EV_A);
1960		2066
1961	adns_processtimeouts (ads, &tv_now);	2067	adns_processtimeouts (ads, &tv_now);
1962	}	2068	}
1963		2069
1964	static void	2070	static void
1965	io_cb (EV_P_ ev_io *w, int revents)	2071	io_cb (EV_P_ ev_io *w, int revents)
1966	{	2072	{
1967	adns_state ads = (adns_state)w->data;	2073	adns_state ads = (adns_state)w->data;
1968	update_now (EV_A);	2074	update_now (EV_A);
1969		2075
1970	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);	2076	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
1971	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);	2077	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
1972	}	2078	}
1973		2079
1974	// do not ever call adns_afterpoll	2080	// do not ever call adns_afterpoll
1975		2081
1976	Method 4: Do not use a prepare or check watcher because the module you	2082	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	2083	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	2084	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	2085	loop is now no longer controllable by EV. The C<Glib::EV> module does
1980	this.	2086	this.
1981		2087
1982	static gint	2088	static gint
1983	event_poll_func (GPollFD *fds, guint nfds, gint timeout)	2089	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
1984	{	2090	{
1985	int got_events = 0;	2091	int got_events = 0;
1986		2092
1987	for (n = 0; n < nfds; ++n)	2093	for (n = 0; n < nfds; ++n)
1988	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events	2094	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
1989		2095
1990	if (timeout >= 0)	2096	if (timeout >= 0)
1991	// create/start timer	2097	// create/start timer
1992		2098
1993	// poll	2099	// poll
1994	ev_loop (EV_A_ 0);	2100	ev_loop (EV_A_ 0);
1995		2101
1996	// stop timer again	2102	// stop timer again
1997	if (timeout >= 0)	2103	if (timeout >= 0)
1998	ev_timer_stop (EV_A_ &to);	2104	ev_timer_stop (EV_A_ &to);
1999		2105
2000	// stop io watchers again - their callbacks should have set	2106	// stop io watchers again - their callbacks should have set
2001	for (n = 0; n < nfds; ++n)	2107	for (n = 0; n < nfds; ++n)
2002	ev_io_stop (EV_A_ iow [n]);	2108	ev_io_stop (EV_A_ iow [n]);
2003		2109
2004	return got_events;	2110	return got_events;
2005	}	2111	}
2006		2112
2007		2113
2008	=head2 C<ev_embed> - when one backend isn't enough...	2114	=head2 C<ev_embed> - when one backend isn't enough...
2009		2115
2010	This is a rather advanced watcher type that lets you embed one event loop	2116	This is a rather advanced watcher type that lets you embed one event loop
…		…
2066		2172
2067	Configures the watcher to embed the given loop, which must be	2173	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	2174	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	2175	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,	2176	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).	2177	if you do not want that, you need to temporarily stop the embed watcher).
2072		2178
2073	=item ev_embed_sweep (loop, ev_embed *)	2179	=item ev_embed_sweep (loop, ev_embed *)
2074		2180
2075	Make a single, non-blocking sweep over the embedded loop. This works	2181	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	2182	similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most
2077	apropriate way for embedded loops.	2183	appropriate way for embedded loops.
2078		2184
2079	=item struct ev_loop *other [read-only]	2185	=item struct ev_loop *other [read-only]
2080		2186
2081	The embedded event loop.	2187	The embedded event loop.
2082		2188
…		…
2084		2190
2085	=head3 Examples	2191	=head3 Examples
2086		2192
2087	Example: Try to get an embeddable event loop and embed it into the default	2193	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	2194	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	2195	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	2196	C<loop_lo> (which is C<loop_hi> in the case no embeddable loop can be
2091	used).	2197	used).
2092		2198
2093	struct ev_loop *loop_hi = ev_default_init (0);	2199	struct ev_loop *loop_hi = ev_default_init (0);
2094	struct ev_loop *loop_lo = 0;	2200	struct ev_loop *loop_lo = 0;
2095	struct ev_embed embed;	2201	struct ev_embed embed;
2096		2202
2097	// see if there is a chance of getting one that works	2203	// see if there is a chance of getting one that works
2098	// (remember that a flags value of 0 means autodetection)	2204	// (remember that a flags value of 0 means autodetection)
2099	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()	2205	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()
2100	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())	2206	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())
2101	: 0;	2207	: 0;
2102		2208
2103	// if we got one, then embed it, otherwise default to loop_hi	2209	// if we got one, then embed it, otherwise default to loop_hi
2104	if (loop_lo)	2210	if (loop_lo)
2105	{	2211	{
2106	ev_embed_init (&embed, 0, loop_lo);	2212	ev_embed_init (&embed, 0, loop_lo);
2107	ev_embed_start (loop_hi, &embed);	2213	ev_embed_start (loop_hi, &embed);
2108	}	2214	}
2109	else	2215	else
2110	loop_lo = loop_hi;	2216	loop_lo = loop_hi;
2111		2217
2112	Example: Check if kqueue is available but not recommended and create	2218	Example: Check if kqueue is available but not recommended and create
2113	a kqueue backend for use with sockets (which usually work with any	2219	a kqueue backend for use with sockets (which usually work with any
2114	kqueue implementation). Store the kqueue/socket-only event loop in	2220	kqueue implementation). Store the kqueue/socket-only event loop in
2115	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).	2221	C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too).
2116		2222
2117	struct ev_loop *loop = ev_default_init (0);	2223	struct ev_loop *loop = ev_default_init (0);
2118	struct ev_loop *loop_socket = 0;	2224	struct ev_loop *loop_socket = 0;
2119	struct ev_embed embed;	2225	struct ev_embed embed;
2120		2226
2121	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)	2227	if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE)
2122	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))	2228	if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE))
2123	{	2229	{
2124	ev_embed_init (&embed, 0, loop_socket);	2230	ev_embed_init (&embed, 0, loop_socket);
2125	ev_embed_start (loop, &embed);	2231	ev_embed_start (loop, &embed);
2126	}	2232	}
2127		2233
2128	if (!loop_socket)	2234	if (!loop_socket)
2129	loop_socket = loop;	2235	loop_socket = loop;
2130		2236
2131	// now use loop_socket for all sockets, and loop for everything else	2237	// now use loop_socket for all sockets, and loop for everything else
2132		2238
2133		2239
2134	=head2 C<ev_fork> - the audacity to resume the event loop after a fork	2240	=head2 C<ev_fork> - the audacity to resume the event loop after a fork
2135		2241
2136	Fork watchers are called when a C<fork ()> was detected (usually because	2242	Fork watchers are called when a C<fork ()> was detected (usually because
…		…
2189		2295
2190	=item queueing from a signal handler context	2296	=item queueing from a signal handler context
2191		2297
2192	To implement race-free queueing, you simply add to the queue in the signal	2298	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	2299	handler but you block the signal handler in the watcher callback. Here is an example that does that for
2194	some fictitiuous SIGUSR1 handler:	2300	some fictitious SIGUSR1 handler:
2195		2301
2196	static ev_async mysig;	2302	static ev_async mysig;
2197		2303
2198	static void	2304	static void
2199	sigusr1_handler (void)	2305	sigusr1_handler (void)
…		…
2273	=item ev_async_send (loop, ev_async *)	2379	=item ev_async_send (loop, ev_async *)
2274		2380
2275	Sends/signals/activates the given C<ev_async> watcher, that is, feeds	2381	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	2382	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	2383	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	2384	similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding
2279	section below on what exactly this means).	2385	section below on what exactly this means).
2280		2386
2281	This call incurs the overhead of a syscall only once per loop iteration,	2387	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	2388	so while the overhead might be noticeable, it doesn't apply to repeated
2283	calls to C<ev_async_send>.	2389	calls to C<ev_async_send>.
		2390
		2391	=item bool = ev_async_pending (ev_async *)
		2392
		2393	Returns a non-zero value when C<ev_async_send> has been called on the
		2394	watcher but the event has not yet been processed (or even noted) by the
		2395	event loop.
		2396
		2397	C<ev_async_send> sets a flag in the watcher and wakes up the loop. When
		2398	the loop iterates next and checks for the watcher to have become active,
		2399	it will reset the flag again. C<ev_async_pending> can be used to very
		2400	quickly check whether invoking the loop might be a good idea.
		2401
		2402	Not that this does I<not> check whether the watcher itself is pending, only
		2403	whether it has been requested to make this watcher pending.
2284		2404
2285	=back	2405	=back
2286		2406
2287		2407
2288	=head1 OTHER FUNCTIONS	2408	=head1 OTHER FUNCTIONS
…		…
2299	or timeout without having to allocate/configure/start/stop/free one or	2419	or timeout without having to allocate/configure/start/stop/free one or
2300	more watchers yourself.	2420	more watchers yourself.
2301		2421
2302	If C<fd> is less than 0, then no I/O watcher will be started and events	2422	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	2423	is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and
2304	C<events> set will be craeted and started.	2424	C<events> set will be created and started.
2305		2425
2306	If C<timeout> is less than 0, then no timeout watcher will be	2426	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	2427	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	2428	repeat = 0) will be started. While C<0> is a valid timeout, it is of
2309	dubious value.	2429	dubious value.
…		…
2311	The callback has the type C<void (*cb)(int revents, void *arg)> and gets	2431	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	2432	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>	2433	C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg>
2314	value passed to C<ev_once>:	2434	value passed to C<ev_once>:
2315		2435
2316	static void stdin_ready (int revents, void *arg)	2436	static void stdin_ready (int revents, void *arg)
2317	{	2437	{
2318	if (revents & EV_TIMEOUT)	2438	if (revents & EV_TIMEOUT)
2319	/* doh, nothing entered */;	2439	/* doh, nothing entered */;
2320	else if (revents & EV_READ)	2440	else if (revents & EV_READ)
2321	/* stdin might have data for us, joy! */;	2441	/* stdin might have data for us, joy! */;
2322	}	2442	}
2323		2443
2324	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	2444	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
2325		2445
2326	=item ev_feed_event (ev_loop *, watcher *, int revents)	2446	=item ev_feed_event (ev_loop *, watcher *, int revents)
2327		2447
2328	Feeds the given event set into the event loop, as if the specified event	2448	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	2449	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	2454	Feed an event on the given fd, as if a file descriptor backend detected
2335	the given events it.	2455	the given events it.
2336		2456
2337	=item ev_feed_signal_event (ev_loop *loop, int signum)	2457	=item ev_feed_signal_event (ev_loop *loop, int signum)
2338		2458
2339	Feed an event as if the given signal occured (C<loop> must be the default	2459	Feed an event as if the given signal occurred (C<loop> must be the default
2340	loop!).	2460	loop!).
2341		2461
2342	=back	2462	=back
2343		2463
2344		2464
…		…
2360		2480
2361	=item * Priorities are not currently supported. Initialising priorities	2481	=item * Priorities are not currently supported. Initialising priorities
2362	will fail and all watchers will have the same priority, even though there	2482	will fail and all watchers will have the same priority, even though there
2363	is an ev_pri field.	2483	is an ev_pri field.
2364		2484
		2485	=item * In libevent, the last base created gets the signals, in libev, the
		2486	first base created (== the default loop) gets the signals.
		2487
2365	=item * Other members are not supported.	2488	=item * Other members are not supported.
2366		2489
2367	=item * The libev emulation is I<not> ABI compatible to libevent, you need	2490	=item * The libev emulation is I<not> ABI compatible to libevent, you need
2368	to use the libev header file and library.	2491	to use the libev header file and library.
2369		2492
2370	=back	2493	=back
2371		2494
2372	=head1 C++ SUPPORT	2495	=head1 C++ SUPPORT
2373		2496
2374	Libev comes with some simplistic wrapper classes for C++ that mainly allow	2497	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	2498	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.	2499	the callback model to a model using method callbacks on objects.
2377		2500
2378	To use it,	2501	To use it,
2379		2502
2380	#include <ev++.h>	2503	#include <ev++.h>
2381		2504
2382	This automatically includes F<ev.h> and puts all of its definitions (many	2505	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	2506	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	2507	put into the C<ev> namespace. It should support all the same embedding
2385	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.	2508	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
…		…
2452	your compiler is good :), then the method will be fully inlined into the	2575	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.	2576	thunking function, making it as fast as a direct C callback.
2454		2577
2455	Example: simple class declaration and watcher initialisation	2578	Example: simple class declaration and watcher initialisation
2456		2579
2457	struct myclass	2580	struct myclass
2458	{	2581	{
2459	void io_cb (ev::io &w, int revents) { }	2582	void io_cb (ev::io &w, int revents) { }
2460	}	2583	}
2461		2584
2462	myclass obj;	2585	myclass obj;
2463	ev::io iow;	2586	ev::io iow;
2464	iow.set <myclass, &myclass::io_cb> (&obj);	2587	iow.set <myclass, &myclass::io_cb> (&obj);
2465		2588
2466	=item w->set<function> (void *data = 0)	2589	=item w->set<function> (void *data = 0)
2467		2590
2468	Also sets a callback, but uses a static method or plain function as	2591	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	2592	callback. The optional C<data> argument will be stored in the watcher's
…		…
2473		2596
2474	See the method-C<set> above for more details.	2597	See the method-C<set> above for more details.
2475		2598
2476	Example:	2599	Example:
2477		2600
2478	static void io_cb (ev::io &w, int revents) { }	2601	static void io_cb (ev::io &w, int revents) { }
2479	iow.set <io_cb> ();	2602	iow.set <io_cb> ();
2480		2603
2481	=item w->set (struct ev_loop *)	2604	=item w->set (struct ev_loop *)
2482		2605
2483	Associates a different C<struct ev_loop> with this watcher. You can only	2606	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).	2607	do this when the watcher is inactive (and not pending either).
2485		2608
2486	=item w->set ([args])	2609	=item w->set ([arguments])
2487		2610
2488	Basically the same as C<ev_TYPE_set>, with the same args. Must be	2611	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	2612	called at least once. Unlike the C counterpart, an active watcher gets
2490	automatically stopped and restarted when reconfiguring it with this	2613	automatically stopped and restarted when reconfiguring it with this
2491	method.	2614	method.
2492		2615
2493	=item w->start ()	2616	=item w->start ()
…		…
2517	=back	2640	=back
2518		2641
2519	Example: Define a class with an IO and idle watcher, start one of them in	2642	Example: Define a class with an IO and idle watcher, start one of them in
2520	the constructor.	2643	the constructor.
2521		2644
2522	class myclass	2645	class myclass
2523	{	2646	{
2524	ev::io io; void io_cb (ev::io &w, int revents);	2647	ev::io io; void io_cb (ev::io &w, int revents);
2525	ev:idle idle void idle_cb (ev::idle &w, int revents);	2648	ev:idle idle void idle_cb (ev::idle &w, int revents);
2526		2649
2527	myclass (int fd)	2650	myclass (int fd)
2528	{	2651	{
2529	io .set <myclass, &myclass::io_cb > (this);	2652	io .set <myclass, &myclass::io_cb > (this);
2530	idle.set <myclass, &myclass::idle_cb> (this);	2653	idle.set <myclass, &myclass::idle_cb> (this);
2531		2654
2532	io.start (fd, ev::READ);	2655	io.start (fd, ev::READ);
2533	}	2656	}
2534	};	2657	};
2535		2658
2536		2659
2537	=head1 OTHER LANGUAGE BINDINGS	2660	=head1 OTHER LANGUAGE BINDINGS
2538		2661
2539	Libev does not offer other language bindings itself, but bindings for a	2662	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	2663	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	2664	any interesting language binding in addition to the ones listed here, drop
2542	me a note.	2665	me a note.
2543		2666
2544	=over 4	2667	=over 4
2545		2668
…		…
2549	libev. EV is developed together with libev. Apart from the EV core module,	2672	libev. EV is developed together with libev. Apart from the EV core module,
2550	there are additional modules that implement libev-compatible interfaces	2673	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	2674	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>).	2675	C<libglib> event core (C<Glib::EV> and C<EV::Glib>).
2553		2676
2554	It can be found and installed via CPAN, its homepage is found at	2677	It can be found and installed via CPAN, its homepage is at
2555	L<http://software.schmorp.de/pkg/EV>.	2678	L<http://software.schmorp.de/pkg/EV>.
2556		2679
		2680	=item Python
		2681
		2682	Python bindings can be found at L<http://code.google.com/p/pyev/>. It
		2683	seems to be quite complete and well-documented. Note, however, that the
		2684	patch they require for libev is outright dangerous as it breaks the ABI
		2685	for everybody else, and therefore, should never be applied in an installed
		2686	libev (if python requires an incompatible ABI then it needs to embed
		2687	libev).
		2688
2557	=item Ruby	2689	=item Ruby
2558		2690
2559	Tony Arcieri has written a ruby extension that offers access to a subset	2691	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	2692	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	2693	more on top of it. It can be found via gem servers. Its homepage is at
2562	L<http://rev.rubyforge.org/>.	2694	L<http://rev.rubyforge.org/>.
2563		2695
2564	=item D	2696	=item D
2565		2697
2566	Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to	2698	Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to
2567	be found at L<http://git.llucax.com.ar/?p=software/ev.d.git;a=summary>.	2699	be found at L<http://proj.llucax.com.ar/wiki/evd>.
2568		2700
2569	=back	2701	=back
2570		2702
2571		2703
2572	=head1 MACRO MAGIC	2704	=head1 MACRO MAGIC
2573		2705
2574	Libev can be compiled with a variety of options, the most fundamantal	2706	Libev can be compiled with a variety of options, the most fundamental
2575	of which is C<EV_MULTIPLICITY>. This option determines whether (most)	2707	of which is C<EV_MULTIPLICITY>. This option determines whether (most)
2576	functions and callbacks have an initial C<struct ev_loop *> argument.	2708	functions and callbacks have an initial C<struct ev_loop *> argument.
2577		2709
2578	To make it easier to write programs that cope with either variant, the	2710	To make it easier to write programs that cope with either variant, the
2579	following macros are defined:	2711	following macros are defined:
…		…
2584		2716
2585	This provides the loop I<argument> for functions, if one is required ("ev	2717	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,	2718	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:	2719	C<EV_A_> is used when other arguments are following. Example:
2588		2720
2589	ev_unref (EV_A);	2721	ev_unref (EV_A);
2590	ev_timer_add (EV_A_ watcher);	2722	ev_timer_add (EV_A_ watcher);
2591	ev_loop (EV_A_ 0);	2723	ev_loop (EV_A_ 0);
2592		2724
2593	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,	2725	It assumes the variable C<loop> of type C<struct ev_loop *> is in scope,
2594	which is often provided by the following macro.	2726	which is often provided by the following macro.
2595		2727
2596	=item C<EV_P>, C<EV_P_>	2728	=item C<EV_P>, C<EV_P_>
2597		2729
2598	This provides the loop I<parameter> for functions, if one is required ("ev	2730	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,	2731	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:	2732	C<EV_P_> is used when other parameters are following. Example:
2601		2733
2602	// this is how ev_unref is being declared	2734	// this is how ev_unref is being declared
2603	static void ev_unref (EV_P);	2735	static void ev_unref (EV_P);
2604		2736
2605	// this is how you can declare your typical callback	2737	// this is how you can declare your typical callback
2606	static void cb (EV_P_ ev_timer *w, int revents)	2738	static void cb (EV_P_ ev_timer *w, int revents)
2607		2739
2608	It declares a parameter C<loop> of type C<struct ev_loop *>, quite	2740	It declares a parameter C<loop> of type C<struct ev_loop *>, quite
2609	suitable for use with C<EV_A>.	2741	suitable for use with C<EV_A>.
2610		2742
2611	=item C<EV_DEFAULT>, C<EV_DEFAULT_>	2743	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
2612		2744
2613	Similar to the other two macros, this gives you the value of the default	2745	Similar to the other two macros, this gives you the value of the default
2614	loop, if multiple loops are supported ("ev loop default").	2746	loop, if multiple loops are supported ("ev loop default").
		2747
		2748	=item C<EV_DEFAULT_UC>, C<EV_DEFAULT_UC_>
		2749
		2750	Usage identical to C<EV_DEFAULT> and C<EV_DEFAULT_>, but requires that the
		2751	default loop has been initialised (C<UC> == unchecked). Their behaviour
		2752	is undefined when the default loop has not been initialised by a previous
		2753	execution of C<EV_DEFAULT>, C<EV_DEFAULT_> or C<ev_default_init (...)>.
		2754
		2755	It is often prudent to use C<EV_DEFAULT> when initialising the first
		2756	watcher in a function but use C<EV_DEFAULT_UC> afterwards.
2615		2757
2616	=back	2758	=back
2617		2759
2618	Example: Declare and initialise a check watcher, utilising the above	2760	Example: Declare and initialise a check watcher, utilising the above
2619	macros so it will work regardless of whether multiple loops are supported	2761	macros so it will work regardless of whether multiple loops are supported
2620	or not.	2762	or not.
2621		2763
2622	static void	2764	static void
2623	check_cb (EV_P_ ev_timer *w, int revents)	2765	check_cb (EV_P_ ev_timer *w, int revents)
2624	{	2766	{
2625	ev_check_stop (EV_A_ w);	2767	ev_check_stop (EV_A_ w);
2626	}	2768	}
2627		2769
2628	ev_check check;	2770	ev_check check;
2629	ev_check_init (&check, check_cb);	2771	ev_check_init (&check, check_cb);
2630	ev_check_start (EV_DEFAULT_ &check);	2772	ev_check_start (EV_DEFAULT_ &check);
2631	ev_loop (EV_DEFAULT_ 0);	2773	ev_loop (EV_DEFAULT_ 0);
2632		2774
2633	=head1 EMBEDDING	2775	=head1 EMBEDDING
2634		2776
2635	Libev can (and often is) directly embedded into host	2777	Libev can (and often is) directly embedded into host
2636	applications. Examples of applications that embed it include the Deliantra	2778	applications. Examples of applications that embed it include the Deliantra
…		…
2643	libev somewhere in your source tree).	2785	libev somewhere in your source tree).
2644		2786
2645	=head2 FILESETS	2787	=head2 FILESETS
2646		2788
2647	Depending on what features you need you need to include one or more sets of files	2789	Depending on what features you need you need to include one or more sets of files
2648	in your app.	2790	in your application.
2649		2791
2650	=head3 CORE EVENT LOOP	2792	=head3 CORE EVENT LOOP
2651		2793
2652	To include only the libev core (all the C<ev_*> functions), with manual	2794	To include only the libev core (all the C<ev_*> functions), with manual
2653	configuration (no autoconf):	2795	configuration (no autoconf):
2654		2796
2655	#define EV_STANDALONE 1	2797	#define EV_STANDALONE 1
2656	#include "ev.c"	2798	#include "ev.c"
2657		2799
2658	This will automatically include F<ev.h>, too, and should be done in a	2800	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	2801	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	2802	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	2803	done by writing a wrapper around F<ev.h> that you can include instead and
2662	where you can put other configuration options):	2804	where you can put other configuration options):
2663		2805
2664	#define EV_STANDALONE 1	2806	#define EV_STANDALONE 1
2665	#include "ev.h"	2807	#include "ev.h"
2666		2808
2667	Both header files and implementation files can be compiled with a C++	2809	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	2810	compiler (at least, thats a stated goal, and breakage will be treated
2669	as a bug).	2811	as a bug).
2670		2812
2671	You need the following files in your source tree, or in a directory	2813	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):	2814	in your include path (e.g. in libev/ when using -Ilibev):
2673		2815
2674	ev.h	2816	ev.h
2675	ev.c	2817	ev.c
2676	ev_vars.h	2818	ev_vars.h
2677	ev_wrap.h	2819	ev_wrap.h
2678		2820
2679	ev_win32.c required on win32 platforms only	2821	ev_win32.c required on win32 platforms only
2680		2822
2681	ev_select.c only when select backend is enabled (which is enabled by default)	2823	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)	2824	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)	2825	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)	2826	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)	2827	ev_port.c only when the solaris port backend is enabled (disabled by default)
2686		2828
2687	F<ev.c> includes the backend files directly when enabled, so you only need	2829	F<ev.c> includes the backend files directly when enabled, so you only need
2688	to compile this single file.	2830	to compile this single file.
2689		2831
2690	=head3 LIBEVENT COMPATIBILITY API	2832	=head3 LIBEVENT COMPATIBILITY API
2691		2833
2692	To include the libevent compatibility API, also include:	2834	To include the libevent compatibility API, also include:
2693		2835
2694	#include "event.c"	2836	#include "event.c"
2695		2837
2696	in the file including F<ev.c>, and:	2838	in the file including F<ev.c>, and:
2697		2839
2698	#include "event.h"	2840	#include "event.h"
2699		2841
2700	in the files that want to use the libevent API. This also includes F<ev.h>.	2842	in the files that want to use the libevent API. This also includes F<ev.h>.
2701		2843
2702	You need the following additional files for this:	2844	You need the following additional files for this:
2703		2845
2704	event.h	2846	event.h
2705	event.c	2847	event.c
2706		2848
2707	=head3 AUTOCONF SUPPORT	2849	=head3 AUTOCONF SUPPORT
2708		2850
2709	Instead of using C<EV_STANDALONE=1> and providing your config in	2851	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	2852	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	2853	F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then
2712	include F<config.h> and configure itself accordingly.	2854	include F<config.h> and configure itself accordingly.
2713		2855
2714	For this of course you need the m4 file:	2856	For this of course you need the m4 file:
2715		2857
2716	libev.m4	2858	libev.m4
2717		2859
2718	=head2 PREPROCESSOR SYMBOLS/MACROS	2860	=head2 PREPROCESSOR SYMBOLS/MACROS
2719		2861
2720	Libev can be configured via a variety of preprocessor symbols you have to define	2862	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	2863	define before including any of its files. The default in the absence of
2722	and only include the select backend.	2864	autoconf is noted for every option.
2723		2865
2724	=over 4	2866	=over 4
2725		2867
2726	=item EV_STANDALONE	2868	=item EV_STANDALONE
2727		2869
…		…
2732	F<event.h> that are not directly supported by the libev core alone.	2874	F<event.h> that are not directly supported by the libev core alone.
2733		2875
2734	=item EV_USE_MONOTONIC	2876	=item EV_USE_MONOTONIC
2735		2877
2736	If defined to be C<1>, libev will try to detect the availability of the	2878	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	2879	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	2880	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	2881	usually have to link against librt or something similar. Enabling it when
2740	the functionality isn't available is safe, though, although you have	2882	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>	2883	to make sure you link against any libraries where the C<clock_gettime>
2742	function is hiding in (often F<-lrt>).	2884	function is hiding in (often F<-lrt>).
2743		2885
2744	=item EV_USE_REALTIME	2886	=item EV_USE_REALTIME
2745		2887
2746	If defined to be C<1>, libev will try to detect the availability of the	2888	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	2889	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	2890	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	2891	be attempted. This effectively replaces C<gettimeofday> by C<clock_get
2750	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the	2892	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the
2751	note about libraries in the description of C<EV_USE_MONOTONIC>, though.	2893	note about libraries in the description of C<EV_USE_MONOTONIC>, though.
2752		2894
2753	=item EV_USE_NANOSLEEP	2895	=item EV_USE_NANOSLEEP
2754		2896
2755	If defined to be C<1>, libev will assume that C<nanosleep ()> is available	2897	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 ()>.	2898	and will use it for delays. Otherwise it will use C<select ()>.
2757		2899
		2900	=item EV_USE_EVENTFD
		2901
		2902	If defined to be C<1>, then libev will assume that C<eventfd ()> is
		2903	available and will probe for kernel support at runtime. This will improve
		2904	C<ev_signal> and C<ev_async> performance and reduce resource consumption.
		2905	If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc
		2906	2.7 or newer, otherwise disabled.
		2907
2758	=item EV_USE_SELECT	2908	=item EV_USE_SELECT
2759		2909
2760	If undefined or defined to be C<1>, libev will compile in support for the	2910	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	2911	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	2912	other method takes over, select will be it. Otherwise the select backend
2763	will not be compiled in.	2913	will not be compiled in.
2764		2914
2765	=item EV_SELECT_USE_FD_SET	2915	=item EV_SELECT_USE_FD_SET
2766		2916
2767	If defined to C<1>, then the select backend will use the system C<fd_set>	2917	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	2918	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	2919	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	2920	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	2921	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	2922	allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might
2773	influence the size of the C<fd_set> used.	2923	influence the size of the C<fd_set> used.
2774		2924
…		…
2798		2948
2799	=item EV_USE_EPOLL	2949	=item EV_USE_EPOLL
2800		2950
2801	If defined to be C<1>, libev will compile in support for the Linux	2951	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,	2952	C<epoll>(7) backend. Its availability will be detected at runtime,
2803	otherwise another method will be used as fallback. This is the	2953	otherwise another method will be used as fallback. This is the preferred
2804	preferred backend for GNU/Linux systems.	2954	backend for GNU/Linux systems. If undefined, it will be enabled if the
		2955	headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled.
2805		2956
2806	=item EV_USE_KQUEUE	2957	=item EV_USE_KQUEUE
2807		2958
2808	If defined to be C<1>, libev will compile in support for the BSD style	2959	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,	2960	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	2973	otherwise another method will be used as fallback. This is the preferred
2823	backend for Solaris 10 systems.	2974	backend for Solaris 10 systems.
2824		2975
2825	=item EV_USE_DEVPOLL	2976	=item EV_USE_DEVPOLL
2826		2977
2827	reserved for future expansion, works like the USE symbols above.	2978	Reserved for future expansion, works like the USE symbols above.
2828		2979
2829	=item EV_USE_INOTIFY	2980	=item EV_USE_INOTIFY
2830		2981
2831	If defined to be C<1>, libev will compile in support for the Linux inotify	2982	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	2983	interface to speed up C<ev_stat> watchers. Its actual availability will
2833	be detected at runtime.	2984	be detected at runtime. If undefined, it will be enabled if the headers
		2985	indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled.
2834		2986
2835	=item EV_ATOMIC_T	2987	=item EV_ATOMIC_T
2836		2988
2837	Libev requires an integer type (suitable for storing C<0> or C<1>) whose	2989	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	2990	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	2991	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"	2992	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.	2993	as well as for signal and thread safety in C<ev_async> watchers.
2842		2994
2843	In the absense of this define, libev will use C<sig_atomic_t volatile>	2995	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.	2996	(from F<signal.h>), which is usually good enough on most platforms.
2845		2997
2846	=item EV_H	2998	=item EV_H
2847		2999
2848	The name of the F<ev.h> header file used to include it. The default if	3000	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	3039	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	3040	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	3041	and time, so using the defaults of five priorities (-2 .. +2) is usually
2890	fine.	3042	fine.
2891		3043
2892	If your embedding app does not need any priorities, defining these both to	3044	If your embedding application does not need any priorities, defining these both to
2893	C<0> will save some memory and cpu.	3045	C<0> will save some memory and CPU.
2894		3046
2895	=item EV_PERIODIC_ENABLE	3047	=item EV_PERIODIC_ENABLE
2896		3048
2897	If undefined or defined to be C<1>, then periodic timers are supported. If	3049	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	3050	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.	3077	defined to be C<0>, then they are not.
2926		3078
2927	=item EV_MINIMAL	3079	=item EV_MINIMAL
2928		3080
2929	If you need to shave off some kilobytes of code at the expense of some	3081	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	3082	speed, define this symbol to C<1>. Currently this is used to override some
2931	some inlining decisions, saves roughly 30% codesize of amd64.	3083	inlining decisions, saves roughly 30% code size on amd64. It also selects a
		3084	much smaller 2-heap for timer management over the default 4-heap.
2932		3085
2933	=item EV_PID_HASHSIZE	3086	=item EV_PID_HASHSIZE
2934		3087
2935	C<ev_child> watchers use a small hash table to distribute workload by	3088	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	3089	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>),	3096	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>	3097	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	3098	watchers you might want to increase this value (I<must> be a power of
2946	two).	3099	two).
2947		3100
		3101	=item EV_USE_4HEAP
		3102
		3103	Heaps are not very cache-efficient. To improve the cache-efficiency of the
		3104	timer and periodics heap, libev uses a 4-heap when this symbol is defined
		3105	to C<1>. The 4-heap uses more complicated (longer) code but has
		3106	noticeably faster performance with many (thousands) of watchers.
		3107
		3108	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>
		3109	(disabled).
		3110
		3111	=item EV_HEAP_CACHE_AT
		3112
		3113	Heaps are not very cache-efficient. To improve the cache-efficiency of the
		3114	timer and periodics heap, libev can cache the timestamp (I<at>) within
		3115	the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>),
		3116	which uses 8-12 bytes more per watcher and a few hundred bytes more code,
		3117	but avoids random read accesses on heap changes. This improves performance
		3118	noticeably with with many (hundreds) of watchers.
		3119
		3120	The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0>
		3121	(disabled).
		3122
		3123	=item EV_VERIFY
		3124
		3125	Controls how much internal verification (see C<ev_loop_verify ()>) will
		3126	be done: If set to C<0>, no internal verification code will be compiled
		3127	in. If set to C<1>, then verification code will be compiled in, but not
		3128	called. If set to C<2>, then the internal verification code will be
		3129	called once per loop, which can slow down libev. If set to C<3>, then the
		3130	verification code will be called very frequently, which will slow down
		3131	libev considerably.
		3132
		3133	The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be
		3134	C<0.>
		3135
2948	=item EV_COMMON	3136	=item EV_COMMON
2949		3137
2950	By default, all watchers have a C<void *data> member. By redefining	3138	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	3139	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,	3140	members. You have to define it each time you include one of the files,
2953	though, and it must be identical each time.	3141	though, and it must be identical each time.
2954		3142
2955	For example, the perl EV module uses something like this:	3143	For example, the perl EV module uses something like this:
2956		3144
2957	#define EV_COMMON \	3145	#define EV_COMMON \
2958	SV *self; /* contains this struct */ \	3146	SV *self; /* contains this struct */ \
2959	SV *cb_sv, *fh /* note no trailing ";" */	3147	SV *cb_sv, *fh /* note no trailing ";" */
2960		3148
2961	=item EV_CB_DECLARE (type)	3149	=item EV_CB_DECLARE (type)
2962		3150
2963	=item EV_CB_INVOKE (watcher, revents)	3151	=item EV_CB_INVOKE (watcher, revents)
2964		3152
…		…
2971	avoid the C<struct ev_loop *> as first argument in all cases, or to use	3159	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++.	3160	method calls instead of plain function calls in C++.
2973		3161
2974	=head2 EXPORTED API SYMBOLS	3162	=head2 EXPORTED API SYMBOLS
2975		3163
2976	If you need to re-export the API (e.g. via a dll) and you need a list of	3164	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	3165	exported symbols, you can use the provided F<Symbol.*> files which list
2978	all public symbols, one per line:	3166	all public symbols, one per line:
2979		3167
2980	Symbols.ev for libev proper	3168	Symbols.ev for libev proper
2981	Symbols.event for the libevent emulation	3169	Symbols.event for the libevent emulation
2982		3170
2983	This can also be used to rename all public symbols to avoid clashes with	3171	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	3172	multiple versions of libev linked together (which is obviously bad in
2985	itself, but sometimes it is inconvinient to avoid this).	3173	itself, but sometimes it is inconvenient to avoid this).
2986		3174
2987	A sed command like this will create wrapper C<#define>'s that you need to	3175	A sed command like this will create wrapper C<#define>'s that you need to
2988	include before including F<ev.h>:	3176	include before including F<ev.h>:
2989		3177
2990	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h	3178	<Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h
…		…
3007	file.	3195	file.
3008		3196
3009	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	3197	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:	3198	that everybody includes and which overrides some configure choices:
3011		3199
3012	#define EV_MINIMAL 1	3200	#define EV_MINIMAL 1
3013	#define EV_USE_POLL 0	3201	#define EV_USE_POLL 0
3014	#define EV_MULTIPLICITY 0	3202	#define EV_MULTIPLICITY 0
3015	#define EV_PERIODIC_ENABLE 0	3203	#define EV_PERIODIC_ENABLE 0
3016	#define EV_STAT_ENABLE 0	3204	#define EV_STAT_ENABLE 0
3017	#define EV_FORK_ENABLE 0	3205	#define EV_FORK_ENABLE 0
3018	#define EV_CONFIG_H <config.h>	3206	#define EV_CONFIG_H <config.h>
3019	#define EV_MINPRI 0	3207	#define EV_MINPRI 0
3020	#define EV_MAXPRI 0	3208	#define EV_MAXPRI 0
3021		3209
3022	#include "ev++.h"	3210	#include "ev++.h"
3023		3211
3024	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	3212	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
3025		3213
3026	#include "ev_cpp.h"	3214	#include "ev_cpp.h"
3027	#include "ev.c"	3215	#include "ev.c"
		3216
		3217
		3218	=head1 THREADS AND COROUTINES
		3219
		3220	=head2 THREADS
		3221
		3222	Libev itself is completely thread-safe, but it uses no locking. This
		3223	means that you can use as many loops as you want in parallel, as long as
		3224	only one thread ever calls into one libev function with the same loop
		3225	parameter.
		3226
		3227	Or put differently: calls with different loop parameters can be done in
		3228	parallel from multiple threads, calls with the same loop parameter must be
		3229	done serially (but can be done from different threads, as long as only one
		3230	thread ever is inside a call at any point in time, e.g. by using a mutex
		3231	per loop).
		3232
		3233	If you want to know which design (one loop, locking, or multiple loops
		3234	without or something else still) is best for your problem, then I cannot
		3235	help you. I can give some generic advice however:
		3236
		3237	=over 4
		3238
		3239	=item * most applications have a main thread: use the default libev loop
		3240	in that thread, or create a separate thread running only the default loop.
		3241
		3242	This helps integrating other libraries or software modules that use libev
		3243	themselves and don't care/know about threading.
		3244
		3245	=item * one loop per thread is usually a good model.
		3246
		3247	Doing this is almost never wrong, sometimes a better-performance model
		3248	exists, but it is always a good start.
		3249
		3250	=item * other models exist, such as the leader/follower pattern, where one
		3251	loop is handed through multiple threads in a kind of round-robin fashion.
		3252
		3253	Choosing a model is hard - look around, learn, know that usually you can do
		3254	better than you currently do :-)
		3255
		3256	=item * often you need to talk to some other thread which blocks in the
		3257	event loop - C<ev_async> watchers can be used to wake them up from other
		3258	threads safely (or from signal contexts...).
		3259
		3260	=back
		3261
		3262	=head2 COROUTINES
		3263
		3264	Libev is much more accommodating to coroutines ("cooperative threads"):
		3265	libev fully supports nesting calls to it's functions from different
		3266	coroutines (e.g. you can call C<ev_loop> on the same loop from two
		3267	different coroutines and switch freely between both coroutines running the
		3268	loop, as long as you don't confuse yourself). The only exception is that
		3269	you must not do this from C<ev_periodic> reschedule callbacks.
		3270
		3271	Care has been invested into making sure that libev does not keep local
		3272	state inside C<ev_loop>, and other calls do not usually allow coroutine
		3273	switches.
3028		3274
3029		3275
3030	=head1 COMPLEXITIES	3276	=head1 COMPLEXITIES
3031		3277
3032	In this section the complexities of (many of) the algorithms used inside	3278	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	3310	correct watcher to remove. The lists are usually short (you don't usually
3065	have many watchers waiting for the same fd or signal).	3311	have many watchers waiting for the same fd or signal).
3066		3312
3067	=item Finding the next timer in each loop iteration: O(1)	3313	=item Finding the next timer in each loop iteration: O(1)
3068		3314
3069	By virtue of using a binary heap, the next timer is always found at the	3315	By virtue of using a binary or 4-heap, the next timer is always found at a
3070	beginning of the storage array.	3316	fixed position in the storage array.
3071		3317
3072	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	3318	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
3073		3319
3074	A change means an I/O watcher gets started or stopped, which requires	3320	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	3321	libev to recalculate its status (and possibly tell the kernel, depending
3076	on backend and wether C<ev_io_set> was used).	3322	on backend and whether C<ev_io_set> was used).
3077		3323
3078	=item Activating one watcher (putting it into the pending state): O(1)	3324	=item Activating one watcher (putting it into the pending state): O(1)
3079		3325
3080	=item Priority handling: O(number_of_priorities)	3326	=item Priority handling: O(number_of_priorities)
3081		3327
…		…
3088		3334
3089	=item Processing ev_async_send: O(number_of_async_watchers)	3335	=item Processing ev_async_send: O(number_of_async_watchers)
3090		3336
3091	=item Processing signals: O(max_signal_number)	3337	=item Processing signals: O(max_signal_number)
3092		3338
3093	Sending involves a syscall I<iff> there were no other C<ev_async_send>	3339	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	3340	calls in the current loop iteration. Checking for async and signal events
3095	involves iterating over all running async watchers or all signal numbers.	3341	involves iterating over all running async watchers or all signal numbers.
3096		3342
3097	=back	3343	=back
3098		3344
3099		3345
3100	=head1 Win32 platform limitations and workarounds	3346	=head1 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS
3101		3347
3102	Win32 doesn't support any of the standards (e.g. POSIX) that libev	3348	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	3349	requires, and its I/O model is fundamentally incompatible with the POSIX
3104	model. Libev still offers limited functionality on this platform in	3350	model. Libev still offers limited functionality on this platform in
3105	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	3351	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
3106	descriptors. This only applies when using Win32 natively, not when using	3352	descriptors. This only applies when using Win32 natively, not when using
3107	e.g. cygwin.	3353	e.g. cygwin.
3108		3354
		3355	Lifting these limitations would basically require the full
		3356	re-implementation of the I/O system. If you are into these kinds of
		3357	things, then note that glib does exactly that for you in a very portable
		3358	way (note also that glib is the slowest event library known to man).
		3359
3109	There is no supported compilation method available on windows except	3360	There is no supported compilation method available on windows except
3110	embedding it into other applications.	3361	embedding it into other applications.
3111		3362
		3363	Not a libev limitation but worth mentioning: windows apparently doesn't
		3364	accept large writes: instead of resulting in a partial write, windows will
		3365	either accept everything or return C<ENOBUFS> if the buffer is too large,
		3366	so make sure you only write small amounts into your sockets (less than a
		3367	megabyte seems safe, but thsi apparently depends on the amount of memory
		3368	available).
		3369
3112	Due to the many, low, and arbitrary limits on the win32 platform and the	3370	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	3371	the abysmal performance of winsockets, using a large number of sockets
3114	recommended (and not reasonable). If your program needs to use more than	3372	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	3373	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	3374	different implementation for windows, as libev offers the POSIX readiness
3117	be implemented efficiently on windows (microsoft monopoly games).	3375	notification model, which cannot be implemented efficiently on windows
		3376	(Microsoft monopoly games).
		3377
		3378	A typical way to use libev under windows is to embed it (see the embedding
		3379	section for details) and use the following F<evwrap.h> header file instead
		3380	of F<ev.h>:
		3381
		3382	#define EV_STANDALONE /* keeps ev from requiring config.h */
		3383	#define EV_SELECT_IS_WINSOCKET 1 /* configure libev for windows select */
		3384
		3385	#include "ev.h"
		3386
		3387	And compile the following F<evwrap.c> file into your project (make sure
		3388	you do I<not> compile the F<ev.c> or any other embedded soruce files!):
		3389
		3390	#include "evwrap.h"
		3391	#include "ev.c"
3118		3392
3119	=over 4	3393	=over 4
3120		3394
3121	=item The winsocket select function	3395	=item The winsocket select function
3122		3396
3123	The winsocket C<select> function doesn't follow POSIX in that it requires	3397	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	3398	requires socket I<handles> and not socket I<file descriptors> (it is
3125	very inefficient, and also requires a mapping from file descriptors	3399	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>,	3400	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	3401	C runtime provides the function C<_open_osfhandle> for this). See the
3128	symbols for more info.	3402	discussion of the C<EV_SELECT_USE_FD_SET>, C<EV_SELECT_IS_WINSOCKET> and
		3403	C<EV_FD_TO_WIN32_HANDLE> preprocessor symbols for more info.
3129		3404
3130	The configuration for a "naked" win32 using the microsoft runtime	3405	The configuration for a "naked" win32 using the Microsoft runtime
3131	libraries and raw winsocket select is:	3406	libraries and raw winsocket select is:
3132		3407
3133	#define EV_USE_SELECT 1	3408	#define EV_USE_SELECT 1
3134	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */	3409	#define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */
3135		3410
3136	Note that winsockets handling of fd sets is O(n), so you can easily get a	3411	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.	3412	complexity in the O(n²) range when using win32.
3138		3413
3139	=item Limited number of file descriptors	3414	=item Limited number of file descriptors
3140		3415
3141	Windows has numerous arbitrary (and low) limits on things. Early versions	3416	Windows has numerous arbitrary (and low) limits on things.
3142	of winsocket's select only supported waiting for a max. of C<64> handles	3417
		3418	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	3419	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	3420	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).	3421	recommends spawning a chain of threads and wait for 63 handles and the
		3422	previous thread in each. Great).
3146		3423
3147	Newer versions support more handles, but you need to define C<FD_SETSIZE>	3424	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	3425	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	3426	call (which might be in libev or elsewhere, for example, perl does its own
3150	select emulation on windows).	3427	select emulation on windows).
3151		3428
3152	Another limit is the number of file descriptors in the microsoft runtime	3429	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	3430	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	3431	or something like this inside Microsoft). You can increase this by calling
3155	C<_setmaxstdio>, which can increase this limit to C<2048> (another	3432	C<_setmaxstdio>, which can increase this limit to C<2048> (another
3156	arbitrary limit), but is broken in many versions of the microsoft runtime	3433	arbitrary limit), but is broken in many versions of the Microsoft runtime
3157	libraries.	3434	libraries.
3158		3435
3159	This might get you to about C<512> or C<2048> sockets (depending on	3436	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	3437	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	3438	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.	3439	calling select (O(n²)) will likely make this unworkable.
3163		3440
3164	=back	3441	=back
3165		3442
3166		3443
		3444	=head1 PORTABILITY REQUIREMENTS
		3445
		3446	In addition to a working ISO-C implementation, libev relies on a few
		3447	additional extensions:
		3448
		3449	=over 4
		3450
		3451	=item C<void (*)(ev_watcher_type *, int revents)> must have compatible
		3452	calling conventions regardless of C<ev_watcher_type *>.
		3453
		3454	Libev assumes not only that all watcher pointers have the same internal
		3455	structure (guaranteed by POSIX but not by ISO C for example), but it also
		3456	assumes that the same (machine) code can be used to call any watcher
		3457	callback: The watcher callbacks have different type signatures, but libev
		3458	calls them using an C<ev_watcher *> internally.
		3459
		3460	=item C<sig_atomic_t volatile> must be thread-atomic as well
		3461
		3462	The type C<sig_atomic_t volatile> (or whatever is defined as
		3463	C<EV_ATOMIC_T>) must be atomic w.r.t. accesses from different
		3464	threads. This is not part of the specification for C<sig_atomic_t>, but is
		3465	believed to be sufficiently portable.
		3466
		3467	=item C<sigprocmask> must work in a threaded environment
		3468
		3469	Libev uses C<sigprocmask> to temporarily block signals. This is not
		3470	allowed in a threaded program (C<pthread_sigmask> has to be used). Typical
		3471	pthread implementations will either allow C<sigprocmask> in the "main
		3472	thread" or will block signals process-wide, both behaviours would
		3473	be compatible with libev. Interaction between C<sigprocmask> and
		3474	C<pthread_sigmask> could complicate things, however.
		3475
		3476	The most portable way to handle signals is to block signals in all threads
		3477	except the initial one, and run the default loop in the initial thread as
		3478	well.
		3479
		3480	=item C<long> must be large enough for common memory allocation sizes
		3481
		3482	To improve portability and simplify using libev, libev uses C<long>
		3483	internally instead of C<size_t> when allocating its data structures. On
		3484	non-POSIX systems (Microsoft...) this might be unexpectedly low, but
		3485	is still at least 31 bits everywhere, which is enough for hundreds of
		3486	millions of watchers.
		3487
		3488	=item C<double> must hold a time value in seconds with enough accuracy
		3489
		3490	The type C<double> is used to represent timestamps. It is required to
		3491	have at least 51 bits of mantissa (and 9 bits of exponent), which is good
		3492	enough for at least into the year 4000. This requirement is fulfilled by
		3493	implementations implementing IEEE 754 (basically all existing ones).
		3494
		3495	=back
		3496
		3497	If you know of other additional requirements drop me a note.
		3498
		3499
		3500	=head1 COMPILER WARNINGS
		3501
		3502	Depending on your compiler and compiler settings, you might get no or a
		3503	lot of warnings when compiling libev code. Some people are apparently
		3504	scared by this.
		3505
		3506	However, these are unavoidable for many reasons. For one, each compiler
		3507	has different warnings, and each user has different tastes regarding
		3508	warning options. "Warn-free" code therefore cannot be a goal except when
		3509	targeting a specific compiler and compiler-version.
		3510
		3511	Another reason is that some compiler warnings require elaborate
		3512	workarounds, or other changes to the code that make it less clear and less
		3513	maintainable.
		3514
		3515	And of course, some compiler warnings are just plain stupid, or simply
		3516	wrong (because they don't actually warn about the condition their message
		3517	seems to warn about).
		3518
		3519	While libev is written to generate as few warnings as possible,
		3520	"warn-free" code is not a goal, and it is recommended not to build libev
		3521	with any compiler warnings enabled unless you are prepared to cope with
		3522	them (e.g. by ignoring them). Remember that warnings are just that:
		3523	warnings, not errors, or proof of bugs.
		3524
		3525
		3526	=head1 VALGRIND
		3527
		3528	Valgrind has a special section here because it is a popular tool that is
		3529	highly useful, but valgrind reports are very hard to interpret.
		3530
		3531	If you think you found a bug (memory leak, uninitialised data access etc.)
		3532	in libev, then check twice: If valgrind reports something like:
		3533
		3534	==2274== definitely lost: 0 bytes in 0 blocks.
		3535	==2274== possibly lost: 0 bytes in 0 blocks.
		3536	==2274== still reachable: 256 bytes in 1 blocks.
		3537
		3538	Then there is no memory leak. Similarly, under some circumstances,
		3539	valgrind might report kernel bugs as if it were a bug in libev, or it
		3540	might be confused (it is a very good tool, but only a tool).
		3541
		3542	If you are unsure about something, feel free to contact the mailing list
		3543	with the full valgrind report and an explanation on why you think this is
		3544	a bug in libev. However, don't be annoyed when you get a brisk "this is
		3545	no bug" answer and take the chance of learning how to interpret valgrind
		3546	properly.
		3547
		3548	If you need, for some reason, empty reports from valgrind for your project
		3549	I suggest using suppression lists.
		3550
		3551
3167	=head1 AUTHOR	3552	=head1 AUTHOR
3168		3553
3169	Marc Lehmann <libev@schmorp.de>.	3554	Marc Lehmann <libev@schmorp.de>.
3170		3555

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